Post on 14-Jan-2022
November 2016
Artificial Photosynthesis Potential and Reality
EUROPEAN COMMISSION
European Commission Directorate-General for Research amp Innovation
E-mail RTD-ENERGY-SR-APeceuropaeu
European Commission
B-1049 Brussels
EUROPEAN COMMISSION
Directorate-General for Directorate-General for Research amp Innovation
20164960
2016 EUR 27987 EN
Artificial Photosynthesis Potential and Reality
Final
Authors Olivier Chartier Paul Baker Barbara Pia Oberč Hanneke de Jong Anastasia Yagafarova (Ecorys) Peter Styring and Jordan Bye (Sheffield University) Rainer Janssen (WIP Renewable Energies) Achim Raschka and Michael Carus (nova Institut) Stavroula Evangelopoulou Georgios Zazias Apostolis Petropoulos Prof Pantelis Capros (E3MLab) Paul Zakkour (Carbon Counts)
November 2016
LEGAL NOTICE
The information and views set out in this report are those of the author(s) and do not necessarily reflect the
official opinion of the Commission The Commission does not guarantee the accuracy of the data included in
this study Neither the Commission nor any person acting on the Commissionrsquos behalf may be held
responsible for the use which may be made of the information contained therein
More information on the European Union is available on the Internet (httpwwweuropaeu)
Luxembourg Publications Office of the European Union 2016
Catalogue number KI-NA-27-987-EN-N
ISBN 978-92-79-59752-7
ISSN 1831-9424
Doi 102777410231
copy European Union 2016
Reproduction is authorised provided the source is acknowledged
Printed in the Belgium
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5
Abstract
Technologies based on Artificial Photosynthesis (AP) offer the potential to deliver sustainable ldquosolarrdquo
alternatives to fossil fuels which are storable and transportable and can thus respond to the problem of
intermittency of other solar wind and marine energy technologies AP research has intensified over the last
decade pursuing multiple approaches or ldquopathwaysrdquo that each have their own relative advantages and
challenges However as most AP technologies are still at a low level of technology readiness it is currently
not possible to identify those AP pathways and specific technologies offering the greatest promise for future
industrial implementation The study argues accordingly that possible public support should retain an
approach that for the time being keeps Europersquos AP options open The proposed roadmap for support for AP
technology development which could be supported under Horizon 2020 foresees actions to address current
gaps in scientific knowledge and technology capabilities while scaling-up the size of projects through the
implementation of pilot projects and demonstrator projects that can validate the viability of AP technologies at
a commercial scale Europe occupies a frontline position in AP research with 60 of the estimated 150
leading global research groups located in Europe However AP research in Europe is relatively less well-
funded than elsewhere notably in the US and Japan European research efforts are also fragmented driven
by national-level strategies and research programmes Therefore the proposed roadmap integrates actions to
support improved networking and cooperation within Europe and possibly at a wider international-level In
turn improved coordination of national research efforts could be achieved through the elaboration of a
common European AP technology strategy aimed at positioning European industry as a leader in the AP
technology field
7
Executive Summary
Objectives and methodology
Artificial photosynthesis (AP) is considered among the most promising new technologies able to deliver
sustainable alternatives to current fuel supplies often viewed as a potential ldquogame changerrdquo in the fields of
energy conversion and energy production AP can be used to produce hydrogen or carbon-based fuels ndash
collectively referred to as ldquosolar fuelsrdquo ndash that offer an efficient and transportable store of (solar) energy which
can be used as an alternative to fossil fuels and as a feedstock for a wide range of industrial processes
Set against the above background the purpose of this study is to provide a full assessment of the situation of
AP providing answers to the questions Who are the main European and global actors in the field What is
the ldquostate of the artrdquo and what are the main ldquobottlenecksrdquo in scientific and technological development What
are the key economic and technological parameters to accelerate industrial implementation Answers to the
questions provide in turn the basis for formulating recommendations on the pathways to follow and the action
to take to maximise the eventual market penetration and exploitation of AP technologies
To gather information on the direction capacities and challenges of ongoing AP development activities the
study has conducted a comprehensive review of scientific and other literature and implemented a survey of
academics and industrial players This information together with the findings from a series of in-depth
interviews provides the basis for a multi-criteria analysis to identify key bottlenecks for the main AP
technology pathways The study findings were validated at a participatory workshop of leading European AP
researchers which also identified scenarios and sketched out roadmaps for actions to support the future
development of AP technologies over the short to long term
Definition of Artificial Photosynthesis
For the purposes of this study artificial photosynthesis is understood to be a process that aims to mimic
the physical chemistry of natural photosynthesis by absorbing solar energy in the form of photons and
using this energy to generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
Main technology pathways for artificial photosynthesis
It is difficult to precisely define the parameters of AP but there are three main identifiable technology pathways
along which research and development is now advancing
Synthetic biology amp hybrid systems aim to mimic existing biological systems that perform different stages of
photosynthesis (ie light-harvesting charge separation or molecule synthesis) and combine them to produce
specific fuel molecules These technologies are at a very early stage (TRL 1-4) however researchers have
already produced small quantities of hydrogen through the water-splitting reaction and have demonstrated the
reduction of carbon dioxide to methane and acetate Research is also investigating the possibility of using
basic cells (biological) to host biological machinery to generate more complex fuel molecules The long-term
goal is to reliably generate large quantities of fuel molecules combining and converting simple starting
compounds such as H2 and CO2 into a series of different compounds using enzymes and synthetic organic
and inorganic catalysts
8
Photoelectrocatalysis combines and integrates photovoltaic (PV) technologies ndash ie semiconductor materials
able to generate electric current from sunlight ndash with water electrolysis in a photoelectrochemical cell (PEC) or
suspensions of photoactive nanoparticles thereby enabling solar energy to be used to produce hydrogen (and
oxygen) via a water-splitting reaction PV technologies are already deployed commercially and are producing
power on a megawatt scale (TRL 7-8) however PECs to perform photoelectrocatalysis are as yet at a
relatively low stage of development (TRL 2-4) The main challenges facing this technology involve developing
materials that have high solar-to-hydrogen (STH) efficiencies are cheap to manufacture (eg use earth-
abundant metals) and are stable for long periods of time
Co-electrolysis uses co-electrolysis of carbon dioxide and water to generate syngas (COH2) by
simultaneously reducing carbon dioxide and water using a high temperature solid oxide cell electrolyser
(SOEC) syngas can then be used to generate simple intermediate compounds that can be used as feedstock
for more complicated chemicals Water electrolysers ndash such as alkaline and polymer electrolyte membrane
(PEM) electrolysers ndash used to convert water into H2 and O2 are mature technologies (TRL 7-8) that have
been commercialised SOECs are at a lower level of development (TRL 3-5) and given their high electricity
requirements current research is focused on increasing their efficiency
Technology pathways for artificial photosynthesis and indicative selection of generated compounds
Source University of Sheffield (PV = Photovoltaics)
AP research in Europe
Research in the AP field ndash bringing together interdisciplinary expertise from biology biochemistry biophysics
and physical chemistry ndash has intensified over the last decade Today more than 150 research groups are
estimated to be active worldwide of which 60 are in Europe1 Interest from industry is growing as well
although it remains limited due to the overall low levels of readiness for commercial application of many AP
technologies
Europe has a diverse community of researchers active in the AP field and covering all the main pathways with
the largest numbers of research groups located in Germany the Netherlands Sweden and the UK The most
significant and only truly pan-European-level research network is AMPEA2 but most networks and consortia
are national Some Member States have set up their own AP research programmes roadmaps and funds and
1 Source study estimates
2 Advance Materials and Processes for Energy Application (AMPEA) which is one of the joint programmes of the Europe nargy Research
alliance (EERA)
9
there has been successful collaboration in several ongoing European-funded FP7 projects Overall however
the level of funding in Europe falls short of that available elsewhere and national research plans (and funding)
seem fragmented and scattered with a short-term focus and lacking an integrated approach with common
research goals and objectives Equally the level of collaboration between academia and industry seems to be
more limited in Europe compared for example to the US or Japan
Relatively few companies are active in the field of AP and they can be counted in the lsquotensrsquo rather than
lsquohundredsrsquo Co-electrolysis is the only area where AP-related technologies are currently commercially viable
while current industry research activities mostly concern photoelectrocatalysis where companies from various
sectors (eg ranging from automotive and electronics to chemicals and oil refining) are involved There is
some industry involvement in synthetic biology amp hybrid systems but it is limited reflecting the early stage of
research activities along this pathway
Main challenges to development and implementation of AP technologies
To form a sustainable and cost-effective part of future European and global energy systems and a source of
high-value and low carbon feedstock chemicals the development of AP technologies must address certain
fundamental requirements
Efficiency in each main step of AP light captureharvesting (eg maximising the percentage of the
spectrum that can be utilised) energy transfer to a reaction centre (eg minimising energy loss during the
transfer) and charge generation and separation to allow the desired chemical reaction to take place (eg
preventing charge recombination)
Durability of the system in terms of the amount of energy that can be produced during the lifetime of an AP
system which is a challenge because of the rapid degradation of some materials under AP system
conditions (eg lack of long-term stability in aqueous conditions or when exposed to sunlight)
Sustainability of material use eg minimising the use of rare and expensive raw materials
To meet these requirements the main AP technology pathways must overcome several gaps in fundamental
knowledge and technology development (see tables) Even if these gaps can be addressed and the feasibility
of commercial- and industrial-scale deployment of AP systems can be demonstrated at a cost level that
enables AP-based products to be competitive in the market place commercial implementation may raise other
practical concerns These may arise in relation to land use water availability and possible environmental or
social concerns which have not yet been fully explored
Synthetic biology amp hybrid systems
Knowledge gaps Technology gaps
Develop molecular and synthetic biology tools to enable
the engineering of efficient metabolic processes within
microorganisms
Improve metabolic and genetic engineering of
microorganism strains
Improve metabolic engineering of strains to facilitate the
production of a large variety of chemicals polymers and
fuels
Enhance (product) inhibitor tolerance of strains
Minimise losses due to chemical side reactions (ie
competing pathways)
Develop efficient mechanisms and systems to separate
collect and purify products
Improve stability of proteins and enzymes and reduce
degradation
Develop biocompatible catalyst systems not toxic to
micro-organisms
Optimise operating conditions and improve operation
stability (from present about gt100 hours)
Mitigate bio-toxicity and enhance inhibitor tolerance at
systems level
Improve product separation at systems level
Improve photobioreactor designs and up-scaling of
photobioreactors
Integrate enzymes into the hydrogen evolving part of
ldquobionic leafrdquo devices
Improve ldquobionic leafrdquo device designs
Up-scale ldquobionic leafrdquo devices
Improve light energy conversion efficiency (to gt10)
Reduce costs of the production of formic acids and other
chemicals polymers and fuels
10
Photoelectrocatalysis
Knowledge gaps Technology gaps
Increase absorber efficiencies
Increase understanding of surface chemistry at
electrolyte-absorber interfaces incl charge transfer
dynamics at SCdyecatalyst interfaces
Develop novel sensitizer assemblies with long-lived
charge-separated states to enhance quantum
efficiencies
Improve charge transfer from solid to liquid
Increase stability of catalysts in aqueous solutions
develop self-repair catalysts
Develop catalysts with low over-potentials
Reduce required rare and expensive catalysts by core-
shell catalyst nanoparticles with a core of an earth-
abundant material
Develop novel water-oxidation catalysts eg based on
cobalt- and iron oxyhydroxide-based materials
Develop efficient tandem absorber structures on (widely
available and cheaper) Si substrates
Develop nanostructure configurations promising
advantages with respect to materials use optoelectronic
properties and enhanced reactive surface area
Reduce charge carrier losses at interfaces
Reduce catalyst and substrate material costs
Reduce costs for tandem absorbers using silicon-based
structures
Develop concentrator configurations for III-V based
tandem absorber structures
Scale up deposition techniques and device design and
engineering
Improve device stability towards long-term stability goal
of gt1000 hours
Improve the STH production efficiencies (to gt10 for
low-cost material devices)
Reduce costs towards a hydrogen production price of 4
US$ per kg
Co-electrolysis
Knowledge gaps Technology gaps
Basic understanding of reaction mechanisms in co-
electrolysis of H2O (steam) and CO2
Basic understanding of the dynamics of
adsorptiondesorption of gases on electrodes and gas
transfer during co-electrolysis
Basic understanding of material compositions
microstructure and operational conditions
Develop new improved materials for electrolytes and
electrodes
Avoid mechanical damages (eg delamination of
oxygen electrode) at electrolyte-electrode interface
Reduce carbon (C) formation during co-electrolysis
Optimise operation temperature initial fuel composition
and operational voltage to adjust H2CO ratio of the
syngas
Replace metallic based electrodes by pure oxides
Improve long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O
(steam) and CO2
Improved stability performance (from present ~50 hours
towards the long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel
composition and operational voltage to adjust H2CO
ratio of the syngas
Improvement of co-electrolysis syngas production
efficiencies towards values facilitating the production of
competitive synthetic fuels via FT-processes
Cost reduction towards competitiveness of synthetic
fuels with fossil fuels
The AP technology development roadmap
Although AP technologies show great potential and despite significant progress made in recent years there is
still a significant way to go before they are ready for industrial implementation Although some aspects of AP-
based systems are well developed the assessment of the existing lsquostate of the artrsquo shows that AP
technologies are generally at low levels of technology readiness (eg TRL 3-4) Moreover there is not yet
compelling evidence to suggest any AP pathway (or sub-approach therein) is ldquomore promisingrdquo than another
This being the case it seems appropriate to adopt an ldquoopenrdquo approach to possible support measures for AP-
related research efforts in the near term which does not single out and prioritise any specific AP pathway or
approach
Nonetheless if AP technologies are to fulfil their potential it will be necessary to achieve the transition from
fundamental research- and laboratory-based validation to demonstration at commercial of near-commercial
scales this ambition forms the long-term goal for the proposed AP technology development roadmap
11
The roadmap distinguishes 3 phases (see figure below) and corresponding recommendations for specific
actions
Phase 1 (short term) Early stage research and scaling-up to pilot projects
Action 1 Support for multiple small AP research projects to address existing knowledge and technology gaps and to
promote long-term advances in scientific knowledge that may contribute to breakthroughs in novel
approaches for AP and to address technology challenges across the board of current (and potential) AP
pathways and approaches
Action 2 Support for enhanced networking of AP research and technology development to reduce fragmentation and
promote coordination and cooperation of research efforts in the AP and related fields through the support for
pan-European networking activities and promotion of research synergies
Action 3 Inducement prize to provide additional stimulus for research technology development and innovation
through a (financial) prize targeting ldquoproof of conceptrdquo of significant advances in the AP field
Phase 2 (medium term) Pilot project implementation and scaling-up to demonstrator projects
Action 4 Support for AP pilot projects to demonstrate the viability of AP concepts through support for a (limited)
number of pilot plant scale projects of the ldquomost promisingrdquo AP technologies
Action 5 Support for AP coordination to ensure effective use of research budgets and to avoid duplication of research
efforts Moving to a common European AP technology strategy requires inter alia alignment of national
research efforts and cooperation at a broader international level Equally to accelerate industrial
implementation cooperation and coordination of activities among the lsquoresearch communityrsquo and industry
should be promoted
Phase 3 (long term) Demonstrator project implementation
Action 6 Support for AP demonstrator projects to demonstrate the viability of AP technologies through support for one
or more demonstrator projects that facilitate the transfer of AP production systems to industrial production for
ldquofirstrdquo markets while allowing an evaluation of the development and integration of the full AP value chain (ie
from upstream supply of materials and components to downstream markets for AP-based products) The
demonstrator project(s) should also address other aspects (eg societal political environmental economic
and regulatory) necessary to evaluate the practical implementation of AP technologies
NB For convenience the timeline of these actions is presented in 3 distinct phases Some AP technologies are however
more advanced than others and could already be at or close to readiness for pilot projects Conversely certain fundamental
knowledge and technology issues cannot expect to be resolved in the short term Accordingly the different phases as
proposed within the roadmap should not be considered to define a strictly chronological sequencetiming of actions
12
Visualisation of the AP technology development roadmap with illustrative project examples
Source Ecorys
Phase 1 Phase 3Phase 2
TRL 9 Industrial Implementation
TRL 6-8 Demonstrator
TRL 3-6 Pilot Projects
TRL 1-3 Fundamental
2017 2025 2035
Example projects- Research on metabolic and genetic engineering of strains for photosynthetic microbial cell factories
- Research on strains for the production of a variety of chemicals polymers and fuels
- Research on the understanding of surface chemistry at electrolyte-absorber interface in PEC
- Development of novel water-oxidation catalysts for direct water splitting
- Research on improvements of light absorption and carrier separation efficiency in PEC devices
- Research on new materials for electrodes and electrolytes in electrolysis cells
-Research to improve the basic understanding of reaction mechanisms in co-electrolysis (dynamics of adsorptiondesorption of gases gas transfer degradation mechanisms etc)
Example of projects - Improvements of operating stability of microbial cell factories
- Improvements of bionic leaf device design
- Study on long-term durability of molecular components used in DS-PEC devices development of active photosensitizer and catalyst
- Improvement of device stability and STH production efficiencies for direct water-splitting devices at pilot plant scale
- Support the development of lab-scale modules and demonstration facilities of electrolysis cells for CO2 valorisation
- Support the upscaling of cells for efficient co-electrolysis of H2O (steam) and CO2 in Solid Oxide Electrolysis Cells (SOEC)
- Development at a near-commercial scale of demonstrator plant(s) for co-electrolysis
Example of projects- Pilot plant scale of photobioreactors for photosynthetic microbial cell factories
- Pilot plant scale of ldquobionic leafrdquo devices
- Development at a near-commercial scale of demonstrator plant(s) for direct water-splitting devices based on several absorber materials (eg dye-sensitised photo-electrochemical cell (DS-PEC) device silicon-based tandem absorber structures)
13
Supporting activities
Looking beyond the technological and operational aspects of the roadmap the study finds several areas
where actions may be taken to provide a better understanding of the AP field and to accelerate development
and industrial implementation namely
Networking and coordination of research With the exception of the few pan-European initiatives (eg AMPEA
and FP7 projects) the degree of collaboration among research groups is low Networking and coordination
activities (for example through Horizon 2020 Coordination amp Support Action - CSA) would contribute to reduce
duplication of efforts and facilitate exchange among researchers
Industry engagement and technology transfer Engagement of industry in development activities which has so
far been relatively limited will become increasingly important as AP technologies move to higher levels of
readiness for commercial implementation Encouraging active involvement of industrial players in research
projects could ease the transfer of technology from the research community to industry (or vice versa) thereby
helping expedite the evolution from prototypes and pilots to marketable products
Public policy and regulatory conditions To encourage industrial implementation and market penetration AP
technologies and products should face a legal and regulatory environment that offers a ldquolevel playing fieldrdquo
compared to other energyfuel types Beyond this reflecting the sustainability and environmental
characteristics of AP there may be a public policy justification for creating a regulatory and legal framework
and possibly other measures to specifically encourage the adoption and diffusion of AP technologies and
products
Safety concerns and societal acceptance AP technologies could potentially raise a number of public
concerns for example the safety aspects of the production storage distribution and consumption of AP-
based products the use of GMOs in synthetichybrid AP processes the use of rare expensive andor toxic
materials extensive land use requirements etc Such legitimate public concerns need to be identified
understood and properly addressed if AP is to overcome barriers to widespread societal acceptance These
aspects should be an integral part of an overall AP research agenda that provides for open dialogue even
from very early stages of technological development and identifies potential solutions and mitigating
measures
Protection of Intellectual Property To become a successful leading player in the development and industrial
application of AP technologies researchers and industry must be able to adequately protect their intellectual
(industrial) property rights (eg patent protection) without this becoming a barrier to overall technology
development and implementation It will be important to both protect European intellectual property rights
while also follow global developments in AP-related patent-protected technologies thereby ensuring that
Europe has a secure strategic position in the AP field and avoiding potentially damaging dependencies on
non-European technologies
15
Table of contents
Abstract 5
Executive Summary 7
Table of contents 15
1 Introduction 21
2 Scope of the study 23
21 Overview of natural photosynthesis 23
22 Current energy usage and definition of artificial photosynthesis 25
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the study29
231 Synthetic biology amp hybrid systems 31
232 Photoelectrocatalysis of water (water splitting) 31
233 Co-electrolysis 31
3 Assessment of the technological development current status and future perspective 33
31 Synthetic biology amp hybrid systems 34
311 Description of the process 34
312 Current status review of the state of the art 35
313 Future development main challenges 38
32 Photoelectrocatalysis of water (water splitting) 39
321 Description of the process 39
322 Current status review of the state of the art 41
323 Patents 44
324 Future development main challenges 45
33 Co-electrolysis 47
331 Description of the process 47
332 Current status review of the state of the art 52
333 Patents 53
334 Future development main challenges 54
34 Summary 54
4 Mapping research actors 57
41 Main academic actors in Europe 57
411 Main research networkscommunities 57
412 Main research groups (with link to network if any) 59
42 Main academic actors outside Europe 62
421 Main research networkscommunities 62
422 Main research groups (with link to network if any) 64
43 Level of investment 66
431 Research investments in Europe 67
432 Research investments outside Europe 71
44 Strengths and weaknesses 73
441 Strengths and weaknesses of AP research in general 73
442 Strengths and weaknesses of AP research in Europe 74
16
45 Main industrial actors active in AP field 76
451 Industrial context 76
452 Main industrial companies involved in AP 76
453 Companies active in synthetic biology amp hybrid systems 77
454 Companies active in photoelectrocatalysis 79
455 Companies active in co-electrolysis 82
456 Companies active in carbon capture and utilisation 83
457 Assessment of the capabilities of the industry to develop AP technologies 85
46 Summary of results and main observations 86
5 Factors limiting the development of AP technology 91
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges 91
52 Current TRL and future prospects of investigated AP RTD initiatives 95
53 Knowledge and technology gaps of investigated AP RTD initiatives 95
54 Coordination of European research 100
55 Industry involvement and industry gaps 101
56 Technology transfer opportunities 104
57 Regulatory conditions and societal acceptance 107
6 Development roadmap 109
61 Context 109
611 General situation and conditions for the development of AP 109
612 Situation of the European AP research and technology base 110
62 Roadmap overview 111
621 Knowledge and technology development 111
622 Supporting and accompanying activities 117
7 References 121
17
List of figures
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton
gradient NADPH and ATP 24
Figure 22 Worldwide consumption of fuel types by percentage 27
Figure 31 General development and supply chain 33 Figure 32 Diagrammatic representation of a PSI-platinum hybrid system 34
Figure 34 Photoelectrochemical cell capable of water oxidation using solar energy 40
Figure 35 PEC reactor types 42
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting
photoelectrochemical cells 47 Figure 37 Schematic diagram of water electrolysis being conducted in an alkaline electrolyser 48
Figure 38 Schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell 49
Figure 41 Research groups in Artificial Photosynthesis in Europe 62
Figure 42 Research groups active in the field of AP globally 66
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020 69
Figure 44 Hondarsquos sunlight-to-hydrogen station 80
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels 85
Figure 61 General development roadmap visualisation 112
19
List of tables
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
36
Table 01 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the
performance data for each device This table was originally constructed by Ursua et al 201211
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis
cell electrolysers This table was originally constructed by Carmo et al 20138 53
Table 41 Number of research groups and research institutions in European countries 59
Table 42 Number of research groups per research area (technology pathway) 60
Table 43 Number of research groups and research institutions in non-European countries 64
Table 44 Number of research groups per research area (technology pathway) 65
Table 45 Investments in the field of artificial photosynthesis 66
Table 46 EU FP6 and FP7 projects on artificial photosynthesis 68
Table 47 Total EU budget on artificial photosynthesis per technology pathway 68
Table 48 Summary of strengths and weaknesses of research globally 73
Table 49 Summary of strengths and weaknesses of research in Europe 75
Table 410 Overview of the size of the industrial community number of companies per pathway 77
Table 411 Organisations in synthetic biology amp hybrid systems 78
Table 412 Organisations in the field of photoelectrocatalysis 79
Table 413 Companies in co-electrolysis 82
Table 414 Organisations active in carbon capture and utilisation 83
Table 415 Summary of findings size of research community 87
Table 416 Summary of findings size of industrial community 89
21
1 Introduction
To establish a world-class technology and innovation sector that is fit to cope with the challenges up to 2020
and beyond the European Commission initiated an update of its EU energy research and innovation (RampI)
policy leading to the publication of the Communication ldquoTowards an Integrated Strategic Energy Technology
(SET) Plan Accelerating the European Energy System Transformation (C (2015) 6317 final) in September
2015 Under the heading ldquoKeeping Technology Actions Openrdquo the SET Plan Integrated Roadmap states that
ldquothe emergence of new technologies required for the overall transition of the energy sector towards
decarbonisation requires breakthroughs which have to be based on fundamental and generic knowledge at
the international state of artrdquo Artificial Photosynthesis counts among the most promising new technologies and
is often considered as a potential ldquogame changerrdquo technology in the fields of energy conversion and energy
production
The study ldquoAssessment of artificial photosynthesisrdquo has been implemented in the first semester of 2016
against this background the study aims to support future policy developments in the area in particular in the
design of public interventions allowing to fully benefit from the potential offered by the technologies The study
has three specific objectives The first objective is to provide a detailed review of the state of the art of artificial
photosynthesis technologies as well as an inventory of research players from the public and private sector
The second objective is to analyse the factors and parameters influencing the future development of these
technologies The third objective is to provide recommendations for public support measures aimed at
maximising this potential
The structure of the report is as follows Section 2 describes the scope of the study with a review of the
different types of Artificial Photosynthesis Section 3 provides an assessment of the technological
development based on a review of the literature Section 4 maps the main academic and industrial actors
Section 5 analyses the factors limiting the development of Artificial Photosynthesis technologies and a
development roadmap is presented in the Section 6
23
2 Scope of the study
21 Overview of natural photosynthesis
Photosynthetic and heterotrophic organisms exist together in a steady state in the biosphere Photosynthetic
organisms capture solar energy in the form of photons this captured energy is used to produce chemical
energy that the organism uses to form adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide
phosphate (NADPH) ATP and NADPH are then used to generate organic compounds such as carbohydrates
from water and carbon dioxide12
Photosynthesis can be broken down into two processes light-dependant
reactions and carbon-assimilation reactions where the latter are driven by the products of the light reactions
In the light reactions electrons are obtained from water molecules that have been oxidised in a process often
referred to as ldquowater splittingrdquo to form electrons (e-) hydrogen ions (H
+) and molecular oxygen (O2) The
electrons are driven through a series of membrane-bound carrier proteins including cytochromes iron-sulphur
proteins and quinones to produce a proton gradient which is used to generate ATP and NADPH this is
summarised in Figure 21 The carbon-assimilation reactions use NADPH ATP electrons and H+ to reduce
carbon dioxide in a series of enzymatic reactions to generate an array of compounds21213
The light-dependent and carbon assimilation reactions of photosynthesis take place in the chloroplasts of
eukaryotic cells Chloroplasts are intracellular organelles with a non-uniform shape similar to that of
mitochondria They both have inner and outer membranes that enclose an inner compartment which is
permeable to small molecules and ions respectively The thylakoid membrane contains the photosynthetic
pigments and enzyme complexes that carry out the light reactions and ATP synthesis and are on the inside of
the inner membrane Chlorophylls are present in the thylakoid membrane and are responsible for absorbing
solar energy in plants An array of chlorophylls is called a photosystem Chlorophylls are green pigments
consisting of long phytol chains with a polycyclic planar structure similar to the protoporphyr in haemoglobin
at the top of the molecule However instead of a Fe2+
at the centre there is a Mg2+
coordinated by four
nitrogen atoms The phytol chain is esterified to a carboxyl group in ring IV The groups on the edge of the ring
(=CH2 and -CH3) can be exchanged for other groups depending on the organism the chlorophyll is present in
The heterocyclic five-ring system that surrounds Mg2+
has an extended polyene structure with alternating
single and double bonds These compounds strongly absorb in the visible region and have high extinction
coefficients Plants always contain chlorophyll α and chlorophyll β which both absorb green light at slightly
different wavelengths this maximises the amount of light the organism can utilise Chlorophylls bind with
specific proteins and membranes to form light-harvesting complexes (LHCs) In addition to chlorophylls which
are the main pigments in plants there are accessory pigments called carotenoids that absorb photons that
have different wavelengths so more of the spectrum can be utilised When a photon is absorbed by a
chlorophyll an electron in the chromophore portion is raised to a higher energy state called the excited state
When the electron moves back down to its ground state it can release the energy as light or heat In
photosynthesis instead of the energy being released as light or heat it is transferred from the excited
chromophore to a neighbouring chromophore in a process called ldquoexcitation transferrdquo1213
All of the pigment molecules in a photosystem can absorb photons and transfer the energy to other pigments
but only a number of pigments are associated with the photochemical reaction centre (PRC) The excitation
energy can be passed through multiple pigment molecules until it reaches a pigment associated with the PRC
The PRC transduces the excitation energy into chemical energy by passing the excitation energy to a nearby
molecule acting as an electron acceptor This leaves the chlorophyll with a positive charge which is
neutralised by another electron donor the electron acceptor becomes negatively charged In this way
excitation caused by photon absorption causes electric charge separation and starts the oxidation-reduction
chain Light-driven electron transfer in chloroplasts during photosynthesis is carried out by a number of multi-
enzyme complexes in the thylakoid membrane1213
24
Photosynthetic bacteria usually have one or two reaction centres Purple bacteria pass electrons through a
pheophytin which is a chlorophyll without the Mg2+
at the centre of the ring to a quinone Green sulphur
bacteria pass electrons through a quinone to an iron-sulphur centre The photosynthetic machinery in purple
bacteria is made up of 3 basic units a single reaction centre (P870) a cytochrome bc1 electron-transfer
complex (similar to complex III found in mitochondria) and an APT synthase Absorption of a photon drives
electrons through pheophytin and a quinone to the cytochrome bc1 complex following which electrons pass
through this complex to the cytochrome bc1 complex and back to the reaction centre This movement of
electrons generates the energy needed by the cytochrome bc1 complex to pump protons across the
membrane and create the gradient that generates ATP1213
The photosynthetic apparatus of cyanobacteria and plants is more complex than that found in a one-system
bacterium due to them containing two photosystems in the thylakoid membrane Photosystem II acts like the
single photosystem found in purple bacteria It should be noted that the water-splitting reaction occurs at
PSII14
When the reaction centre of photosystem II (P680) is excited electrons are driven through the
cytochrome b6f complex which pumps hydrogen ions across the thylakoid membrane to generate a proton
gradient PSI aids in the reduction of NADP+ to NADPH by absorbing a photon at 700 nm to excite an
electron which is passed through a number of carrier molecules to plastoquinone and then to ferredoxin-
NAPD+ reductase which generates NADPH As previously discussed the proton gradient that has been
generated from transferring the electrons that were excited by the photons is used by ATP synthase to
generate ATP To summarise the light-dependent reactions cause water to split into oxygen electrons and
protons which are used to generate a proton gradient form NAPDH from NAPD+ and generate ATP The
main differences between the two photosystems are the wavelengths of light they absorb and that PSII
conducts water oxidation (while PSI does not) Both absorb photons and both are capable of generating
ATP12-16
In the carbon-assimilation reactions ATP and NADPH are used to reduce (gain electrons) carbon
dioxide to form phosphates starch and sugars as part of the Calvin cycle which takes place in the stroma
this process is also known as carbon fixation1213
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton gradient NADPH and ATP
Theoretically the efficiency of natural photosynthetic systems should be around 26 This is calculated by
knowing the energy content of a glucose molecule is 672 kcal mol-1
To generate a glucose molecule 48
photons with a wavelength of 680 nm are needed which together have an energy of 42 kcal per quantum
mole which is equal to 172 kcal mol-1
672 kcal mol-1
divided by 172 kcal mol-1
makes for 26 efficiency
However in reality an efficiency of less than 2 is usually achieved in optimal conditions17
The efficiency of
natural photosynthetic systems is limited by electron-hole recombination which is when the charge separation
25
process is not successful Even when this process is successful up to half of the energy from the excited state
of the chlorophyll is used2 Energy is also used by the organism to ensure other processes within the cell are
functioning The inefficiencies of natural photosynthesis highlight major areas where researchers are looking
to improve in artificial photosynthetic systems and are discussed over the next sections
Photodamage occurs in photosynthetic systems when solar energy cannot be effectively dissipated as heat or
be used to form photosynthetic products fast enough Upon photon absorption chlorophylls are excited to a
singlet state whereby under normal conditions the chlorophyll molecule will either pass the energy to another
chlorophyll molecule by FRET emit a photon or dissipate the energy as heat High levels of light increase the
amount of photosynthesis occurring as well as the amount of time chlorophylls spend in their singlet state
which increases the risk of chlorophylls forming longer-lived triplet states if the energy is not passed on or
dissipated fast enough Chlorophylls in their triplet state can photosensitise toxic chemicals such as singlet
oxygen which causes photodamage18
Natural photosynthetic systems limit photodamage with a process
called non-photochemical quenching using molecules called carotenoids that quench chlorophyll triplet states
by triplet-triplet energy transfer Carotenoids in their triplet state are low energy and quickly release their
energy through heat production and do not facilitate the production of singlet oxygen1213
This method of
photoprotection has been mimicked in artificial photosynthetic systems to extend their lifetimes and enable
them to work under intense light conditions
22 Current energy usage and definition of artificial photosynthesis
The current demand for energy is primarily met by the combustion of fossil fuel resources in the form of coal
crude oil and natural gas
26
Figure 22 shows that the energy demand has doubled over the last 40 years and it should be noted that this
demand is expected to double again by 205031719
The increased energy demand could be met by increasing
fossil fuel combustion However fossil fuel combustion is not a clean process and releases large amounts of
greenhouse gases such as carbon dioxide carbon monoxide and nitrogen oxides The accumulation of these
greenhouse gases in the atmosphere is increasing the average global temperature damaging the ozone layer
and causing more extreme weather2021
From these studies it is clear that using fossil fuels to meet the future
energy demand could cause irreversible damage to the environment and the human population2223
Due to
this much time money and resources are being dedicated to find clean stable and renewable energy
alternatives to fossil fuels2425
Current candidates include wind power tidal power geothermal power and
solar energy while the viability of nuclear power is currently under discussion due to the radioactive wastes
and potential emergency risks The majority of these technologies are currently expensive to operate
manufacture and maintain and produce rather small amounts of energy due to their low efficiencies This
report will focus on how solar energy is being utilised as a renewable energy source The sun provides
100x1015
watts of solar energy annually across the surface of the earth If this solar energy could be
harnessed with 100 efficiency the current energy demand for one year could be met within an hour In total
only 002 of the total solar energy received by earth over a year would be required161726
27
Figure 22 Worldwide consumption of fuel types by percentage Total fuel consumption was equal to 4667 Mtoe in 1973 and 9301
Mtoe in 2013 and is represented by the size difference of the two charts below The figure was adapted from The 2015 Key
World Energy Statistics report3 Mtoe = million tonnes oil equivalent This figure does not state whether the energy came
from a renewable source
Currently one of the best and most developed methods of utilising solar energy (photons) is by using
photovoltaic cells that absorb photons and generate an electrical current This electrical current can be
instantly used as a source of energy or it can be stored in a wide variety of batteries for later use There are a
number of disadvantages to solely relying on photovoltaics to provide us with all of our energy requirements
which are listed below
Photovoltaics can only be used in areas that have high year-round levels of sunlight
The electrical energy has to be used immediately (unless it is stored)
Batteries used to store electrical energy are currently unable to store large amounts of energy have short
lifetimes and their production generates large amounts of toxic waste materials
To address these disadvantages researchers are looking into ways that solar energy can be stored as
chemical energy instead of inside batteries as electricity This is the point where the research being conducted
begins to draw inspiration from photosynthetic organisms14
Photosynthetic organisms have been capable of
utilising solar energy to generate a multitude of complex molecules for billions of years27
Natural
photosynthetic systems are capable of producing two main fuel types hydrogen and carbon-based fuels
Hydrogen is generated from photon-driven in PSII and carbon-based fuels such as carbohydrates and lipids
are generated from the reduction of carbon dioxide with hydrogen (Calvin cycledark reactions)1628
Hydrogen
and carbon-based fuels are the main fuel types researchers aim to produce using artificial photosynthetic
systems29
Hydrogen is produced by splitting (oxidising) water with solar energy catalysts and water oxygen
is a by-product of water oxidation Hydrogen is the simplest fuel to produce and the majority of the
technologies discussed in this report have already had success producing it It is desirable however for
researchers to generate more complex carbon-based fuels such as carbon monoxide methane methanol and
higher order carbon-based compounds using solar energy carbon dioxide and water because carbon-based
fuels have a higher energy density than hydrogen and are used as our primary energy source It should be
noted that hydrogen does not exist in its molecular form in nature which means that it must be produced by
an energy input Hydrogen is most commonly produced by steam reforming natural gas or fossil fuels such as
propane diesel methanol or ethanol8 These methods produce low purity hydrogen and consume fossil fuels
so they do not relieve any fossil fuel dependencies and they further contribute to environmental concerns
In later sections of this literature review some of the main technologies that utilise artificial photosynthesis to
generate fuel molecules are discussed These technologies offer a potential method by which high purity
hydrogen can be produced by the water-splitting reaction using energy obtained from renewable sources
Hydrogen carbon monoxide and carbon dioxide are important feedstocks for making industrial products such
as fertilisers pharmaceuticals plastics and synthetic liquid fuels With more research it is hoped that it will
soon be possible to produce complex molecules from chemical feedstocks that have been produced using
28
renewable energy Technologies that directly convert solar energy to electrical energy (photovoltaics) have
been commercialised for a number of years and can generate electricity on a megawatt scale at large
facilities Success has also been gained with generating hydrogen with a number of technologies such as
biological hybrid systems photoelectrocatalysis and electrolysers (some sub-technologies in this pathway
have been commercialised and can produce power on a megawatt scale) which will also be discussed in this
literature review Some success has been had with generating these more complicated molecules by artificial
photosynthesis from chemical feedstocks but it should be noted that these technologies are still at an early
research and development stage Using recent literature a definition for artificial photosynthesis was
developed for this study and is provided below
Artificial photosynthesis is a process that aims to mimic the physical chemistry of natural
photosynthesis by absorbing solar energy in the form of photons and using the energy to
generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
This is a broad definition of artificial photosynthesis where the term physical chemistry includes any reaction
or process that takes place during natural photosynthesis The term fuel molecules encompasses the term
solar fuel and can include any molecule that the system has been designed to produce such as molecular
hydrogen hydrocarbons alcohols and carbohydrates Biomimetics refers to a system that aims to mimic a
biological system by including some aspects of a biological system such as photosystems I and II chlorophyll
molecules or the electron transport proteinsmolecules Nanotechnology can refer to systems that use organic
chemistry inorganic chemistry or surfaceinterface chemistry to generate artificial photosynthetic systems
Synthetic biology refers to biological systems that have been genetically engineered to either allow or prevent
a biological process to occur
To date much progress has been made in the development of artificial photosynthetic systems since the
conception of the term22628-35
The most common problems associated with artificial photosynthetic systems
arise from
Low efficiency
Inability to utilise the entire spectrum of photon wavelengths
Inability to efficiently separate the charged species
Most systems use expensive noble metals to conduct the chemistry36
Short device lifetimes
Should these synthetic fuels be produced at a large enough scale for commercial use a new set of problems
would appear associated with how the fuels should be stored and distributed Using artificial photosynthesis to
generate hydrocarbons that are already used as an energy source would require fewer infrastructural changes
than switching to a hydrogen economy Furthermore the production process needs to be easily scalable so
that fuels can be produced in a cost-effective way on a terawatt scale in a manner that can keep up with the
ever-increasing energy demand In the next section several different types of artificial photosynthesis
technologies are introduced that aim to effectively utilise solar energy
29
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the
study
Research and development related to the area of artificial photosynthesis encompass several technological
areas The different pathways for artificial photosynthesis are illustrated in
30
Figure 22 along with some of the compounds that can be generated from these technologies on their own or
by combining them It should be noted that while Figure 23 presents a broad selection of potential compounds
that can be produced the actual number of compounds that could potentially be generated by artificial
photosynthetic systems is limitless
Figure 23 Different routes by which artificial photosynthesis can take place and the products that can be generated by utilising the
different technologies This image was generated by The University of Sheffield PV = Photovoltaics
The efficiency and usefulness of artificial photosynthetic technologies are dependent on how well they can
perform three distinctive steps that are found in natural photosynthetic organisms namely
How efficiently they are able to capture incoming photons (percentage of the spectrum that can be
utilised)
How efficiently the system can transfer the energy to a reaction centre (minimising energy loss during the
transfer)
How well the system can generate and separate charges to allow the desired chemical reaction to take
place (preventing charge recombination)
The complexity of artificial photosynthetic systems occurs when multiple charges have to be separated for a
chemical reaction to occur The production of hydrogen and oxygen from the water-splitting reaction which is
probably the simplest reaction these systems must be capable of still involves the transfer of four electrons
and the generation of more complicated compounds will require even more charge-separation events to occur
The following sections discuss the artificial photosynthetic technologies as depicted in
31
Figure 22 which are synthetic biologyhybrid systems photoelectrochemical catalysis and co-electrolysis
231 Synthetic biology amp hybrid systems
This pathway aims to take existing biological systems that perform different stages of photosynthesis such as
the light-harvesting charge separation or molecule synthesis steps and combine them so they are able to
produce specific fuel molecules These biological molecules can be modified or combined with other biological
molecules or synthetic organicinorganic compounds so that they are able to produce specific fuel molecules
more efficiently It is known that natural photosynthetic systems contain a number of crucial components that
need to be included in synthetic biology and hybrid artificial photosynthetic systems For example they should
contain a light harvester (semiconductor or molecular dye) a reduction co-catalyst (hydrogenase mimic or
noble metal) and an oxidation co-catalyst (photosystem II mimic that is capable of producing molecular oxygen
and hydrogen) It should be noted that these technologies are at a very early stage of development
(laboratory level technology readiness level (TRL 1-4)) and are many years away from being commercialised
Briefly researchers are capable of producing small quantities of hydrogen through the water-splitting reaction
and have demonstrated the reduction of carbon dioxide to methane and acetate Researchers are also
investigating the possibility of using basic cells (biological) to host biological machinery that is capable of
generating more complex fuel molecules The long-term goal of these technologies will be to reliably generate
large quantities of specific fuel molecules from simple starting compounds such as hydrogen and carbon
dioxide which are combined and converted into a series of different compounds using a series of enzymes
and synthetic organic and inorganic catalysts
232 Photoelectrocatalysis of water (water splitting)
This pathway aims to develop efficient photovoltaics and photoelectrochemical catalysts that utilise earth-
abundant metals capable of generating oxygen and hydrogen through the water-splitting reaction38
Photovoltaics can be used to generate electrical energy directly from sunlight Photovoltaicssemiconductors
can be used in photoelectrochemical cells to produce hydrogen from the water-splitting reaction PVs and
PECs are among the most advanced areas of artificial photosynthesis Photovoltaics utilise semiconductor
materials that are capable of directly generating electrical currents (electrical energy) when exposed to certain
wavelengths of light These semiconductors have to be capable of utilising a range of photon wavelengths
efficiently and must have long lifetimes Photovoltaics have been commercialised and are producing power on
a megawatt scale Future developments in this field aim to increase device efficiency and lower the costs
associated with them (TRL 7-8) Photoelectrochemical cells are capable of producing electricity and fuel
molecules when exposed to certain wavelengths of light Fuel molecules such as hydrogen are produced by
electrolysing water (splitting water) which could provide an unlimited source of hydrogen that could be used to
generate power or reduce carbon dioxide Water-splitting cells require semiconductors that are able to support
rapid charge transfer at the semiconductoraqueous interface have long-term stability in aqueous
environments and are capable of utilising a range of photon wavelengths30
233 Co-electrolysis
This pathway provides an alternative method by which water oxidation can be performed Alkaline
electrolysers and polymer electrolyte membrane electrolysers have been mature technologies now for a
number of years and are capable of converting water and electricity to hydrogen and oxygen The co-
electrolysis pathway aims to use carbon dioxide-water co-electrolysis to generate syngas (COH2) which is
produced by simultaneously reducing carbon dioxide and water using high temperature solid oxide cell
electrolysers (SOECs)39
Syngas can be used to generate simple intermediate compounds that can be used
as feedstock for more complicated chemicals used in fertilisers pharmaceuticals plastics and synthetic liquid
fuels Methanol is an example of a simple molecule that can be made from syngas The dehydration of
methanol can be used to generate the cleaner fuel dimethyl ether which is being considered as a future
energy source40
As a technique to produce power co-electrolysis offers a number of advantages over other
techniques such as photovoltaics and wind power in that it is not site-specific and can continuously generate
32
power However these devices require large amounts of electricity to function which affects their operating
costs It is likely that these systems will have their electricity supplied to them by solar or wind power farms in
the near future
33
3 Assessment of the technological development current status and future perspective
This literature review will focus on three technologies (synthetic biologybiological hybrid systems
photovoltaicsphotoelectrochemical cells and co-electrolysis) that are currently using artificial photosynthesis
to generate energy in the form of electricity and fuels The majority of research into these technologies has
focused on improving device efficiencies lifetimes and producing hydrogen The review will conclude with
discussions about the fuels researchers are currently producing potential large-scale facilities to produce the
fuels and finally the potential directions research into artificial photosynthesis could pursue Figure 3 shows a
general development and supply chain for technologies that aim to use artificial photosynthesis to convert
solar energy into power and fuels It should be noted that each technology will have its own set of specific
challenges which will be discussed at the end of each respective section This literature review was
constructed using material from a number of sources such as peer-reviewed journals official reports and
patents that have been filed
Figure 31 General development and supply chain for technologies that aim to use a combination of photovoltaics and
photoelectrochemical cell artificial photosynthetic technologies to convert solar energy into power and fuels
34
31 Synthetic biology amp hybrid systems
311 Description of the process
Artificial photosynthetic systems that utilise synthetic biology aim to modify existing natural photosynthetic
systems at the genetic level or combine them with other biological systems and synthetic compounds to
produce a specific fuel or improve efficiency It should be noted that technologies based on using synthetic
biology and hybrid systems to produce solar fuels are still at the research and development stage (TRL 1-4)
however the use of these systems to produce a limited number of fine chemicals is more advanced with a TRL
3-7 The majority of technologies developed in this pathway have focused on producing hydrogen and only a
limited number of technologies are capable of producing more complex fuel molecules It should also be noted
that most of these systems are only capable of producing small amounts of fuel molecules for a short period of
time Natural photosynthetic systems can be broken down into three distinct processes that these systems
have to mimic light-harvesting energy transfer and charge generationseparation (catalytic reactions)1437
For
these technologies to be successful the systems have to be designed so that they consist of electron donors
and acceptors and attempt to mimic light-driven charge separation2 Generally these technologies aim to
combine biological molecules that have catalytic activity (enzymes such as PSI [NiFe]-hydrogenase and
[FeFe]-hydrogenase) or combine the enzymes with synthetic inorganic and organic compounds9 Examples of
when these systems have been successfully created are discussed below with figures and the TRLs of the
technologies are given after each technology has been discussed
Illustrations
Figure 32 A simplified diagrammatic representation of a PSI-platinum hybrid system that is used to generate H2 can be found below
showing PSI P700 chlorophyll a apoprotein A1 (red) and PSI P700 chlorophyll a apoprotein A2 (blue) The electron provided
by ascorbate is transferred to a cytochrome c6 where a photon excites the electron which is then passed through PSI where
it is transferred to the platinum (Pt) catalyst to generate molecular hydrogen This figure drew inspiration from Fukuzumi
2015 and Gorka et al 20149
35
Figure 33 A diagrammatic representation of a FeFe-hydrogenase I ndash cadmium sulphur (CdS) hybrid system that is used to generate
H2 The faded red structure represents the surface topography of FeFe-hydrogenase I the blue arrows represent the
movement of the electrons through the Fe-S clusters where hydrogen ions are converted to H2 and the yellow structures
represent the CaI capped CdS nanorods The figure was constructed using inspiration from Wilker et al 2014 using the
PBD file 3C8Y and edited using PyMol software12
312 Current status review of the state of the art
The first example of researchers successfully producing light-driven hydrogen from an artificial complex
composed of biological molecules and platinum was achieved by combining the PSI subunit PsaE from
Thermosynechococcus elongtus with an oxygen tolerant [NiFe]-hydrogenase from Ralstonia eutropha H16 to
form a PSI-hydrogenase complex This complex in presence of ascorbate (electron donor) was capable of
light-driven hydrogen production at a rate of 058 microM (mg chlorophyll)-1
h-1
41-43
(TRL 3)
Hydrogenases are enzymes that catalyse the reversible oxidation of molecular hydrogen while platinum is
also capable of reversibly photocatalytically oxidising hydrogen44
Researchers recently showed that when a
platinum nanocluster was attached to a PSI molecule the complex was able to produce hydrogen at a rate of
673 microM (mg chlorophyll)-1
h-1
- the general structure of this complex is highlighted in Figure 323
Systems
based on these original concepts have been optimised to achieve higher hydrogen production efficiencies of
up to 244 microM (mg chlorophyll)-1
h-1
It should also be noted that the electron donor (ascorbate) had to be
present in excess in both cases2345
It should also be noted that these hydrogen production rates are
comparable to those of natural photosynthetic systems which occur at a rate of ca 300 microM (mg chlorophyll)-1
h-1
46
(TRL 3-4)
Researchers recently proposed a model by which hydrogen can be generated using CaI capped CdS
nanorods The authors reported that light is absorbed by the CdS nanorods to excite two electrons which are
then transferred into the CaI cap where the two electrons are used to reduce two protons (H+) and generate
hydrogen (electrons are replaced in CdS by ascorbate) In a recent publication the authors showed that it is
possible to combine the CdSCaI nanorods with [FeFe]-hydrogenase in place of PSI (ascorbate is used as an
electron donor) In this biomimetic system the electrons are transferred to [FeFe]-hydrogenase where they
reduce H+ to hydrogen This system was shown to have a quantum efficiency of 20 be active for up to 4
hours and had a total turnover of 106 hydrogen before activity was lost The loss in activity was found to be
due to the inactivation of the CaI cap at the end of the CdS rod147
36
Figure 3 represents the system and process described above where the blue arrows represent the movement
of electrons from the CdSCaI nanorods to the iron-sulphur clusters in [FeFe]-hydrogenase (TRL 3-4)
Researchers were recently able to produce hydrogen using a PSI-cobaloxime complex when it was
illuminated with natural light Cobaloximes are vitamin B12 mimics capable of catalysing H+ reduction
Cobaloximes offer a number of advantages over hydrogenases in that they are not sensitive to oxygen their
synthesis is relatively simple and they are constructed from relatively cheap materials In this system sodium
ascorbate used a sacrificial electron donor and cytochrome c6 transported the electrons to the PSI-cobaloxime
complex Upon light absorption the electrons were excited and transported through PSI to the bound
molecular catalyst cobaloxime where hydrogen production occurs27
The maximum rate for the photoreduction
of water by this hybrid system was measured to be 170 mol hydrogen (mol PSI)-1
min-1
as was reached within
10 minutes of illumination It should be noted that after 90 minutes hydrogen production levelled off giving a
total turnover of 5200 mol hydrogen mol PSI-1
27
It is thought that the activity of the hybrid decreased due to
the dissociation of cobaloxime from PSI research efforts are currently underway to stabilise the hybrid
system27
This system is of particular merit because the PSI-cobaloxime hybrid is composed of earth-
abundant materials unlike the hybrid systems containing precious metals It should also be noted that there
are multiple molecular catalysts for hydrogen production other than the cobaloximes that can offer improved
stability solubility in water and better activity and have been discussed in a recent review6 (TRL 3-4)
The production of hydrogen at a rate of 2200 plusmn 460 micromol mg Chl-1
h-1
(a faster rate than natural photosynthetic
systems) has recently been demonstrated This was accomplished by generating a hybrid system consisting
of a PSI complex tethered to a [FeFe]-hydrogenase using a 18-octanedithiol nanowire and also crosslinking
cytochrome c6 to the PSI complex This four component system was then placed in a sodium phosphate buffer
containing the electron donor sodium ascorbate at pH 65 and illuminating the sample with natural light48
The
authors also reported results for complexes consisting of different nanowire lengths (3-10 carbons) and a
chain length of 8 carbons was found to give the highest hydrogen production rates this is most likely due to
the chain being long enough to minimise steric hindrance between the two proteins The hybrid system
retained its activity for up to four hours and it should be noted that the decrease in activity was attributed to
depletion of the electron donor (full activity was regained upon replenishing the ascorbate) It should also be
noted that the hybrid system regained its full hydrogen-evolving activity after being stored in anoxic conditions
at room temperature for 100 days48
(TRL 3)
The technologies above are only a few examples of the methods researchers have used to generate hydrogen
from hybrid systems Table 31 below summarises hydrogen production rates by a number of different hybrid
systems that all incorporate PSI into their complex The information in Table 31 was originally summarised by
Utschig et al 20156 All of the technologies in this table have a TRL of 3-4
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
PSI-catalyst system Rate of H2 production
[mol H2 (mol PSI)-1 s
-1]
TON (time hours)
PSI-nanoclusters photoprecipitated long liveda 49
0002 ndc (2000)
PSI-[NiFe]-hydrogenase genetic fusion 41
001 ndc (3)
PSI-nanoclusters photoprecipitated short-liveda 49
013 ndc (2)
PSI-[FeFe]-hydrogenase-PetF in vitro complexb 50
031 ndc (05)
PSI-Ni diphosphinea 51
073 (3)
PSI-[FeFe]-hydrogenase-Fd protein complexb 50
107 ndc (1)
PSI-molecular wire-Pt nanoparticlea 52
11 (12)
PSI-NiApoFd protein deliverya 51
125 (4)
PSI-cobaloximea 27
283 (15)
PSI-Pt nanoparticlea 45
583 (4)
PSI-molecular wire-[FeFe]-hydrogenasea 48
524 ndc (3)
a Redox mediator Cyt c6
b Redox mediator PC
c nd not determined
37
Researchers have generated a hybrid photocatalyst system capable of splitting water to produce hydrogen
and oxygen and capable of reducing carbon dioxide by rational design The system uses a semiconductor as
the light harvester and a biomimetic complex mimicking photosystem I as a molecular catalyst37
This work
highlights that the understanding of artificial photosynthetic systems is increasing as rational design can now
be used to construct biomimetic artificial photosynthetic systems (TRL 2)
Unicellular organisms such as Chlamydomonas reinhardtii are a type of green algae that can produce
hydrogen light-dependently using the enzyme [FeFe]-hydrogenase However hydrogen production rates in
photoactive organisms are limited by a number of physiological constraints This is due to electrons
generated by PSI being used in a number of reactions other than hydrogen production5354
Most photoactive
organisms will contain a form of photosynthetic electron transport ferredoxin (PETF) protein which provides
photosynthetic electrons generated by PSI for a number of metabolic pathways All of these pathways
compete for electrons with [FeFe]-hydrogenase Researchers recently genetically modified the affinity PETF
has for PETF-dependent ferredoxin-NADP+-oxidoreductase (FNR) without comprising the affinity PETF has
for [FeFe]-hydrogenase In this modified system PETF is still able to supply [FeFe]-hydrogenase with
electrons that it used to produce hydrogen but is less able to supply electrons to FNR which means that fewer
carbon dioxide fixation reactions occur Hydrogen production rates increased by nearly 5x in wild type cells
that had modified PETF53
(TRL 3)
Microbial biocathodes consist of an electrode that has electrochemically active microorganisms immobilised
onto its surface which are capable of reducing protons to hydrogen These systems offer a number of
advantages in that the cathode can be constructed from cheap materials and the microorganisms can self-
regenerate55
The first microbial biocathode consisted of three phases (1) acetate and hydrogen are oxidised
at a bioanode that has been inoculated with a mixed culture of electrochemically active microorganisms to
release carbon dioxide (2) only hydrogen is fed into the bioanode (3) the polarity of the cells is reversed
(direction of electron flow) and hydrogen production begins at the cathode55
Initially after the polarity is
reversed methane was produced at the biocathode and not hydrogen (TRL 4)
Bio-catalysed electrolysis is a microbial fuel cell-based technology that is capable of generating hydrogen and
other reduced products from electron donors (acetatewastewater) however these systems require an
external power source56
In this system acetate is oxidised at the anode by microorganisms in the presence of
high concentrations of ammonium and the electrons are transferred to a platinum catalyst (cathode) where
they reduce protons to hydrogen56
(TRL 3)
A recent paper has reported the reduction of carbon dioxide to acetate and methane using a water-splitting
reaction to produce hydrogen and sodium bicarbonate as the carbon source using microbial electrosynthesis
(MES)57
This system used an assembly of graphite felt and a stainless steel cathode This paper is important
because it presents the use of electrode materials derived from earth-abundant elements showcasing them
as particularly suitable for industrial scale-out due to their low cost (TRL 3)
Researchers at the University of Oxford developed a biological tool called ldquoSimCellrdquo A SimCell is a simple
non-replicating cell that has no well-defined function until a plasmid containing DNA coding a specific
function is inserted into the cellrsquos genome The inserted DNA could potentially provide all of the genetic
information needed by the cell to produce the proteins and enzymes required to produce specific fuel
molecules The SimCell has been optimised to be simple so that most of the energy the cell is using will go
towards carrying out the function of the newly inserted gene instead of maintaining numerous intracellular
processes5859
The SimCell could allow researchers to insert genetic information that codes the production of
target fuels thereby greatly increasing the number of potential fuel targets and the efficiency with which they
can be produced It is possible that this technology could be patented once it reaches a higher level of
maturity and a working system is demonstrated (TRL 1)
38
313 Future development main challenges
Synthetic biology amp hybrid artificial photosynthetic systems primarily focus on producing hydrogen however
research focused on the production of hydrocarbons using technologies such as MES is gaining momentum
Although these technologies are currently at the laboratory research and development stage (TRL 1-4) they
are improving quickly At a very small laboratory scale the systems are becoming efficient enough to produce
hydrogen at a rate that is comparable to that which occurs in natural photosynthesis although some
researchers have reported even faster production rates
Synthetic biology amp hybrid systems need to address a number of specific challenges before they can be
considered as commercially viable options for producing solar fuels Below some preconditions and
challenges regarding certain such systems are described
Protein Hybrid Systems
For proteins to be active their primary amino acid sequence must fold and adopt the correctly folded
structure Misfolded proteins can exhibit severely diminished activities
Proteins (and enzymes) are inherently unstable and sensitive to the pH temperature pressure and buffer
components and will often degrade over time which limits their use
Most hydrogenases are sensitive to oxygen so they must be kept under anaerobic conditions
Biological molecules can be produced at a large scale as shown by the biopharmaceutical industry
However the amount of biological molecules needed to produce the amount of fuel required to support
mankind would be huge and has not been calculated
One of the strongest properties of enzymes is that they exhibit a high level of specificity they are able to
produce specific molecules of high purity
Enzymes can be redesigned to give them new or improved functions within different environments60
However modifying protein and enzyme function is not trivial it is often a time-consuming process that
requires thorough understanding of the system although predictive tools for protein engineering are
improving
Enzymes are often very large molecules in which only a small percentage of the amino acid residues are
actively involved in catalysis Researchers could reduce the complexity of biological systems drastically if
they focused on stripping the enzyme down so it contains only the residues and cofactors needed for
catalytic activity on a simplified base framework of amino acids
Microorganisms
In a recent paper researchers investigated how hydrogen production can be enhanced and suppressed in
vitro They state that the main limitations of hydrogen production in microorganisms are the systemrsquos
sensitivity to oxygen and the competition between hydrogenases and NADPH-dependent carbon dioxide
fixation If these issues can be solved the technologies would be closer to commercialisation50
It should be
noted that microorganisms are capable of producing a number of fine chemicals on a commercial scale (these
are often produced in smaller amounts)
Microorganisms are highly complex in that a multitude of chemical reactions must take place so that the
organism can continue to function at the most basic level These extra reactions are major drawbacks if
these organisms are to be used to produce fuel molecules as most of the absorbed energy cannot be
used to produce the fuel molecules
To overcome this problem various aspects of the organismsrsquo genetic information can be modified to
minimise energy loss through side reactions
SimCells are simplified cells in that number of chemical reactions needed to sustain the organism are
minimised this means that more energy can dedicated to fuel production However these technologies
are currently in early stages of research and development and are not close to being produced on an
industrial scale
39
It is likely that fuel-producing microorganisms will have to be capable of expelling the fuel molecules
otherwise the fuel-producing cells will have to be destroyed to obtain the molecules
A major advantage of bacterial systems is that their genetic information can be modified so that they
produce a number of different fuel molecules However this is not a trivial task and the microorganisms
may not be able to survive when large concentrations of the fuel molecules are present
Bacterial cells can survive in a number of harsh conditions and they do not have to be in an ultra-clean
environment
Synthetic biology and hybrid systems face a unique challenge in that these systems are made by or are
genetically modified organisms (GMOs) GMOs are often subject to negative media attention and are often
portrayed and viewed to be unsafe by the public which means that the public may not want their fuel coming
from this source Some of the concerns surrounding the use of GMOs are valid and need to be investigated
One of the main concerns about the use of GMOs pertains to whether the GMO could have a severe effect on
the environment if it managed to migrate into the wild However this issue could be addressed by only using
GMOs that are not able to replicate (ie they are obtained from a secured parent cell) However most of the
concerns the public may have regarding GMOs could be solved by educating about GMOs and providing a
large body of scientific evidence that supports their safety
It should be noted that the authors could find no relevant patents for artificial photosynthetic technologies that
utilise synthetic biology amp hybrid systems
In conclusion synthetic biology amp hybrid systems that produce solar fuels are currently in the laboratory
research and development stage and it is too early to determine whether they would be a commercially viable
option However current research is promising and shows that they could be a valuable part of generating
solar fuels due to their high level of specificity and ability to be reengineered to carry out new and specialised
chemistry
32 Photoelectrocatalysis of water (water splitting)
321 Description of the process
This pathway aims to develop efficient photovoltaics and photoelectrocatalysts that utilise earth-abundant
metals capable of generating oxygen and hydrogen by splitting water38
The water-splitting (water oxidation)
reaction is one of the most advanced areas of artificial photosynthesis These systems that directly produce
fuel molecules from sunlight are currently in the early researchproof-of-concept stage (TRL 2-4) This means
that they are a number of years away from being a commercially viable method to produce synthetic fuels31
Water oxidation involves the removal of 4e- and 4H
+ to generate molecular oxygen (O2) and molecular
hydrogen (H2) In nature water oxidation is carried out by photosystem II in natural photosynthetic systems
The water-splitting reaction has the potential to provide a clean sustainable and abundant source of
hydrogen that could be used as energy or to reduce carbon dioxide to higher order hydrocarbons which is
why a considerable amount of time and money has been spent trying to improve the process
Photovoltaic cells (PVs) also known as solar cells utilise semiconductor materials that are capable of directly
generating electrical currents when exposed to certain wavelengths of light Light absorption by the
semiconductor promotes an electron from the low energy valence band to the higher energy conduction band
This creates an electron-hole pair that can be transported through the electrical device to provide power
Research focusing on PVs has focused on improving their efficiencies Initially efficiencies lt1 were
obtainable but the most recent generation of PVs can achieve efficiencies gt45 Research has shown that
the efficiencies of PVs can be greatly improved by using multi-junction instead of single-junction devices60
Efficiencies of different PV models have increased over the last 40 years this plot is courtesy of the National
Renewable Energy Laboratory Golden CO The most recent PVs have long lifespans (gt20 years) low
40
pollution levels and low operating costs30
However PVs do have some drawbacks in that they are expensive
to manufacture can only be used during the day in areas that receive a lot of sunlight utilise a fraction of the
available spectrum and it is problematic to store the energy in batteries3360
Problems associated with long-
term storage of energy could be overcome by storing the energy in chemical bonds of molecules such as
hydrogen alcohols and hydrocarbons which is why the research in the following section is of importance It
should also be noted that PVs have a TRL of 9 as they have been successfully commercialised and can
provide power on a megawatt scale
Photoelectrochemical cells (PECs) are capable of producing fuel molecules when exposed to certain
wavelengths of light or paired with a semiconductor (PV) Hydrogen can be produced by the water-splitting
reaction Figure 3 shows a schematic diagram of a PEC which is capable of conducting water oxidation in
two separate chambers Currently there are two primary methods by which solar fuels can be generated from
the water-splitting reaction in PECs The first is by direct photoelectrocatalysis at the semiconductor-
electrolyte interface (occurring at a solid-liquid junction) and the second is by coupling the electrochemical
(PEC) reaction directly to a buried p-n junction PV230
Both of these approaches require the generation of a
photovoltage sufficient to split water (gt 123 V)30
Photoelectrodes in PECs must have high surface stability
good electronic properties and suitable light absorption characteristics Water-splitting cells require
semiconductors that are able to support rapid charge transfer at the semiconductoraqueous interface have
long-term stability in aqueous environments and are capable of utilising a range of photon wavelengths30
These functions are obtained by using multi-junction configurations that use p- and n-type semiconductors
with different band gaps and surface-bound electrocatalysts The brief description of PVs has been included
because they are an essential component for a number of systems that photocatalytically split water
Illustration
Figure 34 The illustration below shows a photoelectrochemical cell capable of water oxidation using solar energy consisting of
separated titanium dioxide (TiO2) and platinum (Pt) electrodes Water oxidation occurs at the TiO2 electrode where oxygen
is formed during which process protons (H+) and electrons (e
-) are released H
+ pass through an ion transport membrane to
a compartment containing the Pt electrode where electrons are used to reduce H+ to hydrogen After this hydrogen can be
stored as an energy source or it can be used to reduce carbon dioxide to higher order hydrocarbon compounds
Explanations
According to the National Renewable Energy Laboratory the greatest gains in efficiency have been made with
the multi-junction PV cells The first single-junction GaAs cells developed in the mid-1970s and had
efficiencies of ca 22 (which is better than most of the more recent PV cells that have been developed) The
most recent multi-junction technologies have achieved efficiencies of up to 46 It should also be noted that a
41
greater number of p-n junctions a PV has the greater its efficiency This is because each p-n junction is made
from a different semiconductor material that can absorb light at a different wavelength increasing the amount
of the spectrum that can be utilised PVs based on crystalline silicone cells have shown a slow increase in
efficiency over the last 40 years starting from 14 and increasing up to 276 PVs utilising thin-film
technologies now achieve efficiencies up to 223 Thin-film technologies are a particularly promising branch
of PV due to them being lightweight and the potential to manufacture them by printing which would decrease
their production and installation costs
Figure 3 shows a schematic diagram of a PEC cell that was developed by Honda and Fujishima in 1972 and
was capable of the water-splitting reaction using a TiO2 electrode in tandem with a platinum electrode61
PEC
cells consist of three basic components a semiconductor a reference electrode and an electrolyte The
principles of PEC cell operation are simple a photon is absorbed by the semiconductor (TiO2) material which
causes electron excitation and the excited electrons move to the reference electrode (Pt) through a metal
wire The movement of electrons between the two materials generates a positive charge (holes) at the
semiconductor which combines with electrons in the oxygen molecules of water to form molecular oxygen
and hydrogen ions At the reference electrode the electrons can combine with hydrogen ions to form
molecular hydrogen In this study oxygen was generated at the TiO2 electrode and hydrogen was generated at
the platinum electrode
Since the initial study by Honda and Fujishima researchers have spent much time developing new materials
for anodic and cathodic processes that are capable of carrying out the same process with greater efficiency
and ability to produce more products3061
Currently the cost-effectiveness of using solar energy systems to
generate power and fuels is constricted by the low energy density of sunlight which means low cost materials
need to be developed so that enough sunlight can efficiently be captured Sunlight availability is intermittent
which means that the captured energy needs to be efficiently stored The efficiency of PEC water-splitting
devices is determined by measuring their solar-to-hydrogen (STH) efficiency this is defined as the amount of
chemical energy produced in the form of hydrogen divided by the solar energy input without the use of any
external bias10
322 Current status review of the state of the art
Currently there are two main approaches that are used to photocatalytically split water into oxygen and
hydrogen The first method utilises a single-visible-light photocatalyst (this is essentially a PV) with a narrow
band gap capable of absorbing photons in the visible spectrum has a suitable thermodynamic potential for
water splitting and is stable enough to avoid photocorrosion4 The drawbacks of this system include that it is
only capable of utilising a small region of the spectrum and the collection of oxygen and hydrogen is difficult
due to them being produced in the same region2 The second method uses a two-step mechanism which
utilises two photocatalysts (photoanode and photocathode) in tandem similar to the Z-scheme present in
natural photosynthetic systems2 This setup enables the system to utilise a larger range of visible light
because the free energy required to drive each photocatalyst can be tuned compared to the one-step system
(one photon is needed for each photocatalyst) In this system the oxygen and hydrogen generated via water
oxidation can be separated more efficiently from each other because they are produced at different sites
(oxygen is produced at the anode and hydrogen is produced at the cathode) this also reduces the likelihood
of charge recombination462
This second system is more desirable as the oxygen and hydrogen evolution
sites can be contained in separate compartments62
Theoretical calculations have highlighted that the
maximum efficiency of a single absorber PEC system could reach 29-31 whereas a tandem PEC system
could reach 40-41 further highlighting the advantages of using tandem devices106364
Efficiency calculations
for three different PEC configurations a single photoabsorber system a dual stacked photoabsorber system
and a dual side-by-side photoabsorber system were reported to be 112 228 and 155 respectively
These systems differ in the spatial distribution and number of photoabsorbers which will affect the range of
wavelengths that can be absorbed and therefore the materialsrsquo STH efficiency10
It should be noted that the
practical efficiencies of these devices will often be much lower due to the inefficiencies associated with the
catalysts and reaction overpotentials10
These calculations show that the best way to achieve higher
efficiencies in PEC devices is to use a dual stacked photoabsorber system
42
Recently four PEC reactor types were conceived to represent a range of systems that could be used to
generate hydrogen from solar energy Each system design can be seen in Figure 31062
Types 1 and 2 are
based on relatively simple photoactive nanoparticle suspensions whereas types 3 and 4 are based on more
complex planar arrays a brief discussion of each system is given below It should be noted that quoted STH
efficiencies are optimised values and do not take into account material lifetimes
Figure 35 The figure below shows four PEC reactor types including a (a) Type 1 reactor showing the plastic bags containing the
suspended hydrogen- and oxygen-evolving photoactive particles (b) Type 2 reactor showing the plastic bags containing
separated suspensions of photoactive particles capable of separately evolving hydrogen and oxygen (c) Type 3 reactor
showing a sun-orientated panel containing a layered PEC cell capable of producing hydrogen and oxygen and (d) Type 4
reactor the design of which consists of a similar layered PEC cell to Type 3 with an added parabolic receiver that is able to
concentrate light onto the PEC cell throughout the day These figures were originally constructed by Pinaud et al 201310
Type 1 This reactor has the simplest design It consists of a transparent plastic bag that contains a
suspension of photoactive particles in 01 M potassium hydroxide that are capable of simultaneously
evolving hydrogen and oxygen by the water-splitting reaction Photons at a variety of different wavelengths
are able to penetrate the plastic bag whereas the electrolyte evolved gases and photoactive particles are
held within the bag The authors modelled the photoactive particles as spherical cores coated with
photoanodic and photocathodic particles The authors calculated that this reactor type could achieve a
realistic STH efficiency of 10 however it should be noted that the hydrogen and oxygen evolved in this
system would need to be separated1062
43
Type 2 The design of this reactor is very similar to that of Type 1 in that it consists of photoactive
nanoparticles suspended in an electrolyte contained within clear plastic bags The main difference
between the two systems is that the hydrogen- and oxygen-evolving particles are contained within
separate bags which reduces the need for a gas separation step and increases the safety of the system
However the bag design has to be more complicated in that a redox mediator is required along with a
porous bridge between the hydrogen- and oxygen-evolving bags The STH efficiency of this system was
calculated to be 51062
Type 3 This reactor is composed of a layered planar electrode consisting of multiple photoactive layers
(multi-junction PVsemiconductor) that is submerged within an aqueous solution containing 01 M
potassium hydroxide encased within a clear plastic case Multiple photoactive materials are used so that
more of the solar spectrum can be utilised The anode (oxygen evolution) is at the top of the cell where it
absorbs photons of a certain wavelength and allows others to pass through to the cathode where they are
absorbed into another layer to drive hydrogen evolution Due to the fixed orientation of these cells they
have to have a large surface area to ensure they can absorb the maximum amount of photons1062
Type 4 This reactor is similar to Type 3 in that it consists of a flat PEC cell of a similar design (gas
evolution occurs in a similar manner) The main difference is that a solar tracking concentrator system is
used to focus sunlight onto the PEC cell This means that smaller and more efficient PEC devices can be
used to reduce costs The STH efficiency of this system was calculated to 12-181062
The costs of hydrogen production for a power plant consisting of each reactor type were assessed (it should
be noted that costs for Type 3 and 4 plants were considered to be more accurate due to availability of PV
pricing)10
Type 1 $160 H2kg
Type 2 $320 H2kg
Type 3 $1040 H2kg
Type 4 $400 H2kg
During early work with PEC cells researchers were able to achieve efficiencies of 124 for hydrogen
production over 20 hours using a p-GaInP2(Pt)rsquoTJGaAs electrode However it should be noted that current
density decreased from 120 mAcm2 to 105 mAcm
2 over the course of the experiment which was caused by
damage to the PEC cell65
Therefore although this device was able to achieve high efficiencies its lifetime
was too low
Water oxidation in the presence of a photocatalyst that has been combined with a co-catalyst has been
reported2 The role of the co-catalyst is to provide extra reaction sites and decrease the activation energy for
oxygen and hydrogen evolution Researchers must carefully choose the type of co-catalyst to use this is
because although some noble metal catalysts like platinum and rhodium are good for enhancing hydrogen
production they also catalyse the reverse reaction (convert oxygen and hydrogen back to water)66
To
circumvent this issue transition-metal oxides are often used as co-catalysts instead of noble metals as these
do not catalyse water reformation However these compounds are often more susceptible to degradation
when they are exposed to the reactive environments found in PECs4
The first example of a metal oxide being used to split water into oxygen and hydrogen was carried out by a
dinuclear ruthenium complex (the blue dimer)34
Electrochemical and in situ spectroscopic measurements
were used to measure hydrogen production when platinum and rhodium plates deposited with chromia
(Cr2O3) were used as the water-splitting material4 Coreshell-structured nanoparticles that have a noble metal
or noble metal oxide core and a Cr2O3 shell have been shown to be capable of acting as a co-catalyst for the
water-splitting reaction This presents a mechanism by which noble metals could be used as co-catalysts the
Cr2O3 shell has been shown to supress the water reformation reaction when coated onto palladium and
platinum cores4 Multiple transition metal oxides such as NiOx RuO2 and TiO2 can be used as co-catalysts
when they are treated with appropriate chemicals (TRL 3-4)
44
Researchers recently reported a catalyst that was formed upon the oxidative polarization of an inert indium tin
oxide electrode immersed in a solution containing 100 mM potassium phosphate and 05 mM cobalt (II) ions at
pH 70 Upon initiation of electrolysis at 129 V oxygen production was shown to increase linearly over 12
hours to reach a maximum of 100 microM h-1
(after 12 hours electrolysis was stopped)67
The catalytic activity of
the reaction was also shown to be pH-dependent which suggests that the hydrogen phosphate ion is the
proton acceptor (TRL 3)
In a recent publication a multi-junction design was used to absorb light and provide energy for the water-
splitting reaction Multi-junction PVs are more efficient as they are able to absorb enough solar energy to
provide the free energy for water splitting The researchers developed a device based on an oxide
photoanode (Fe2O3 or WO3) and a dye-sensitized solar cell which performs unassisted water splitting with an
efficiency of up to 31 STH Incoming light was absorbed by the photoanode where the water-splitting
reaction and oxygen evolution takes place Electrons were transported to a platinum cathode where hydrogen
formation occurred68
(TRL 4)
Recently researchers demonstrated water splitting using tandem PEC cells where PtCdSCGSACGSe was
used as the photocathode (hydrogen evolution) and NiOOHFeOOHMoBiVO4 as the photoanode (oxygen
evolution) The cell was able to sustain a stable water-splitting reaction for 2 hours with an STH efficiency of
06769
(TRL 3)
Photochemical hydrogen production by nanowire arrays has been shown to be advantageous to more
traditional system designs because they use less precious material to produce7071
Researchers recently
showed that photoelectrochemical hydrogen production from water was possible using InP nanowire arrays In
these systems the chosen nanowire compound has a layer of silicone oxide (SiO2) deposited onto its surface
and then a co-catalyst deposited onto the surface of Efficiencies of 52 and 64 were obtained when the
InP nanowires were deposited with platinum and MoS3 respectively7072
Silicon is an abundant low-cost
semiconductor commonly used in PV devices and photoelectrochemical hydrogen generation at the
Sielectrolyte interface has been extensively studied for decades Hydrogen is evolved slowly at the
Sielectrolyte interface which has led to research efforts to modify the surfaces with electrocatalysts such as
platinum and ruthenium which are showing good activities and efficiencies71
(TRL 2-3)
323 Patents
Patents have been filed for systems based on nanoparticle suspensions and PECs some of which are
discussed below
A patent was filed in 2012 detailing a suspension of photoactive nanoparticles consisting of metallic cores and
semiconductor photocatalytic shells that can photocatalytically split water to directly obtain hydrogen The
efficient and unassisted photocatalytic splitting of water by the nanoparticles is based on resonant absorption
from surface plasmon in the metal coresemiconductor shell hybrid nanoparticles which can extend the
absorption spectra towards the visible-near infrared range This increases the solar energy conversion
efficiency When the photoactive nanoparticles are used in combination with scintillator nanoparticles the
hybrid photocatalytic nanoparticles can be used to convert nuclear energy into hydrogen73
(TRL 3-4)
A patent was recently filed for a PEC cell consisting of melanin melanin precursors melanin derivatives
melanin variants melanin analogues natural or synthetic pure or mixed with organic or inorganic compounds
metals ions drugs that act as the water electrolyzing material This technology uses solar energy as the sole
or main source of energy to produce hydrogen from water The system integrates a semiconductor material
and a water electrolyser inside a monolithic design that produces hydrogen directly from water using light
between 200 to 900 nm as the main or sole source of energy The technology aims to meet two criteria (i) the
system or light-absorbing compound should generate enough energy for the water-splitting reaction to be
45
completed and (ii) the materials need to be cheap to source and exhibit high stability in water and the reactive
environment The authors claim that all of these requirements can be met by melanin and related compounds
which represents a significant advancement in PEC design The technology can be used to generate
hydrogen oxygen and high energy electrons It can also be used to perform the opposite reaction and
generate water from electrons protons and oxygen and can be coupled to other processes generating a
multiplication effect It can also be used for the reduction of carbon dioxide nitrates and sulphates or others74
(TRL 2-3)
In 2008 a patent was filed describing a PEC system that could produce hydrogen from water The device was
comprised of (i) an electrolytic bath containing an electrode for catalytic oxidation an electrode for catalytic
reduction and an ion separation film disposed between the two electrodes immersed in an aqueous
electrolyte solution and (ii) a photoelectrode positioned outside the electrolytic bath and electrically connected
to the two electrodes This PEC system is characterised by disposing a photoelectrode at a position which
does not contact the electrolyte solution preventing the lowering of the photoelectrode activities and which
maximises hydrogen production efficiency75
(TRL 3)
In 2014 a patent was filed describing an invention that was able to generate hydrogen by
photoelectrocatalytic water splitting The system also incorporated an analysis-detection system The system
was composed of a photoelectrocatalytic water-splitting hydrogen generation device constructed from TiO2
nanorods (water splitting) a platinum cathode and a AgAgCl reference electrode submersed in a 05 M
Na2SO4 solution Results from five tests of the system were reported After the first hour the device produced
17-20 micromolh hydrogen for four hours as determined by the inbuilt detector76
(TRL 3)
324 Future development main challenges
The generation of electricity from solar energy by PVs has been successfully commercialised with the most
recent solar projects being able to produce electricity at a cost of 015 ndash 035 $kWh on a megawatt scale31
Facilities such as the Solar Star Power Station and the Topaz Solar Farm in the USA are examples of facilities
that use PV technologies that are capable of producing electricity (TRL 8-9) These facilities can now be
constructed because the cost of PVs has dramatically decreased and their efficiencies have increased over
the last few years Laboratory research is currently focused on further increasing the efficiency of PVs and
combining these systems with catalysts that are capable of generating higher order hydrocarbon fuels
However the reduction of carbon dioxide to liquid fuels is a complicated multi-electron process still in the
proof-of-concept stage (TRL 2-3) It is also recommended that the new materials PVs are constructed from
should ideally be cheap abundant lightweight flexible and robust If all of these requirements are met the
costs associated with manufacturing PVs as well as transporting installing and maintaining them may
continue to fall
There are a number of general challenges facing PEC technologies (including suspensions of photoactive
nanoparticles and PECs) that are associated with
Effectively designing facilities
Developing methods to store the generated energy
Developing transportation networks to distribute the energy
A major drawback of these facilities is that they can only be used during daylight hours when there is a clear
sky This highlights the importance of being able to store large amounts of energy at these facilities that can
be used outside of daylight hours It has been proposed that the energy generated from these facilities could
be stored in new types of batteries or as chemicals such as hydrogen and hydrocarbons Storing the energy
in the form of hydrocarbons would be particularly useful as these have a much higher energy density than
batteries and hydrogen The infrastructure to store and transport these already exists for them to be used as a
fuel However as previously mentioned the ability to convert hydrogen and carbon dioxide into high order
hydrocarbons using PVs and PECs is still in the proof-of-concept stage10
46
There are also a number of challenges related to the materials used to construct photoactive nanoparticles
and PECs This is particularly problematic because the most useful semiconductors are not stable in water
and the metal oxides that are stable in water often have band gaps that are too large for light absorption1065
There are three main processes that cause electrodes to degrade over long periods of time and inhibit their
activity
The first is corrosion which occurs with all materials over long periods of time
The second is catalyst poisoning which is caused by the introduction of solution impurities and it has
been shown that low concentrations of impurities can have a huge impact on electrode efficiency77
Finally changes to the composition and morphology (structurestructural features) of the electrode can
decrease their efficiency30
As well as exhibiting high stability the materials have to be highly efficient However there is a relationship
between device complexity cost and efficiency Water-splitters using triple-junction amorphous silicon or IIIndashIV
semiconductors have good efficiencies (5-10) but have high costs and device complexities Simpler
approaches using oxide-based semiconductors in a dual-absorber tandem approach have reported STH
conversion efficiencies up to 0368
This highlights the need to find cheaper and efficient semiconductor
materials that can be used for the water-splitting reaction
The US Department of Energy has determined that the price of hydrogen production delivery and dispensing
must reach $2-3 kg-1
before it can compete with current fuels2 It is also important to take into account the
infrastructural changes that would be required if we were to adopt a hydrogen fuel economy To meet the
current power demands of the US with PVs that have an efficiency of 10 a total area of 58000 miles2 would
be required The cost of semiconductors capable of these efficiencies amounts to tens of trillions of dollars
not taking into account the huge costs associated with the required changes to the infrastructure32
These
facilities would only be viable in areas where there is an abundance of sunshine (such as deserts) which also
proposes large fuel transportation issues In the majority of areas the sun is intermittent and only provides
about 6-10 hours of sunshine per day This further highlights the need to be able to store the energy in the
form of chemical bonds that can be used at any time as well as be more easily stored as batteries can only
store a relatively small amount of the energy required and can produce large quantities of toxic materials when
manufactured
It has been calculated that for the water-splitting reaction to provide one third of the energy required by the
human population in 2050 10000 solar plants each covering a 5 km x 5 km area (250000 km2 = 1 of the
Earthrsquos desert area) and with an overall efficiency of 10 would be required Each plant would be capable of
generating ca 570 tonnes of hydrogen from 5100 tonnes of water per day which together could provide up to
33 of the energy needed by mankind in 2050 The hydrogen could be transported directly to on-site
chemical plants where other organic compounds can be manufactured4 Figure 3 shows two diagrams of one
of these sites that could be capable of producing 570 tonnes of hydrogen per day24
The amount of each
material needed to generate methane from hydrogen and carbon dioxide is given in the formula below in
tonnes The US Department of Energy has set a target for hydrogen-producing PEC devices to have an STH
efficiency of 10 and a 5000 hour durability by 201878
120784119815120784 + 119810119822120784 rarr 119810119815120786 + 119822120784
120784(120784120790120787) + 120788120784120789120782 rarr 120784120784120790120782 + 120786120787120788
According to these calculations 6270 tonnes of carbon dioxide would be required by each of these plants per
day to use all of the hydrogen generated to produce 2280 tonnes of methane and 4560 tonnes of oxygen
The amount of carbon dioxide required increases linearly as the hydrocarbon chain length increases The cost
of manufacturing the number of PEC cells required to carry out this amount of water splitting would be in the
tens of trillions of euros taking into account the current costs of the associated technology62
The energy
required to power these facilities would be obtained from renewable sources such as wind wave and PVs
47
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting photoelectrochemical cells H2 generated
on-site could be used to reduce CO2 to higher order hydrocarbon fuel molecules These figures were constructed by Maeda
et al 2010 and Tachibana et al 2012
33 Co-electrolysis
331 Description of the process
Electrolysers capable of conducting the water-splitting reaction have existed for centuries Water electrolysers
are capable of converting water and DC electricity into gaseous hydrogen and oxygen according to the
equation below879
High-pressure (30 bar) water electrolysers have been commercially available since 1951
In 2012 there were at least 13 manufactures that produce low temperature water electrolysers (3 using
polymer electrolyte membranes (PEM) and 3 using alkaline electrolysers)79
Electrolysers that use solid oxide
electrolysers cells (SOECs) under high temperatures were first developed in the 1980s in the HotElly project
Currently SOEC technologies are still in the research and development stage It should also be noted that the
water splitting thermodynamics are more favourable at the higher temperatures used in SOECs as compared
to alkaline electrolysers PEMs and PECs ΔG = 237 kJ mol-1
(123 eV) at ambient temperatures ΔG = 183 kJ
mol-1
(095 eV) at 900 oC
8397980
120784119815120784119822 + 119811119810 rarr 120784119815120784 + 119822120784
Co-electrolysis is a technique that can be used to produce fuel molecules directly from electricity water and
carbon dioxide Interest in the electrolysis of water and carbon dioxide originated in the 1960s where it was
thought that the process could be used to supply oxygen for submarines and spacecraft81
Unlike electrolysis
co-electrolysis aims to simultaneously split water and reduce carbon dioxide to form a mixture of carbon
monoxide (CO) hydrogen and oxygen this process is highlighted in the equation below The term ldquosyngasrdquo
(synthesis gas) refers to a mixture of carbon monoxide and hydrogen and not the oxygen component
Producing fuels by co-electrolysis consists of three main stages carbon dioxide capture syngas synthesis
and storage of the renewable energy as chemical bond energy (hydrogen and hydrocarbon fuels)80
This
chemical reaction is achieved by using high temperature solid oxide cell electolysers3982-84
Co-electrolysis
offers a number of advantages over solar and wind power farms Solar and wind power farms have to be built
in site-specific areas to maximise their power output which limits the number of countries that would be able
to host these technologies (solar power is only viable for countries that have high levels of sun year-round)
Solar and wind power farms are only able to generate power intermittently which makes them unsuited to
coping with sudden large power demands (solar farms can only generate power during daylight hours) It has
been suggested that batteries and thermal fluids could be used to store energy for peak times However
48
these storage methods are currently unable to store large amounts of energy suffer from short lifetimes and
generate large amounts of harmful waste during production531
Technologies capable of co-electrolysing
water and carbon dioxide to syngas and hydrocarbons are at an early stage of development TRL 2-4
119810119822120784 + 119815120784119822 rarr 119810119822 + 119815120784 + 119822120784
It is also important to note that all electrolysers require a large input of electrical energy which would have to
be from renewable sources if this technology is to relieve its dependence on fossil fuels The major cost
associated with solid oxide electrolysis cells (SOEC) comes from the electricity required to operate them and
the feedstock while the cost of the electrolyser material makes up a smaller proportion of the total cost39
If
SOECs were designed to utilise wind and solar energy (PVssemiconductors) to generate the electricity they
require their operating costs would decrease significantly However this also decreases the number of
countries that could host electrolysers as their operation is again dependent on solar and wind energy It
would also be advantageous to incorporate a Fischer-Tropsch process that is capable of generating synthetic
hydrocarbons from the resulting syngas that can be used in the existing infrastructure3985
Syngas can be used to generate simple intermediate compounds that can be used as feedstock for more
complicated chemicals such as fertilisers pharmaceuticals plastics and synthetic liquid fuels Methanol is an
example of a simple molecule that can be made from syngas The dehydration of methanol can be used to
generate the cleaner fuel dimethyl ether which is being considered as a future energy source40
The most
common feedstocks for the production of hydrocarbon fuels are fossil fuels and biomass However it is hoped
that sustainable feedstocks such as carbon dioxide and water can be used to generate syngas which can be
converted into hydrocarbon fuels through Fischer-Tropsch synthesis39
Illustrations
Figure 37 A schematic diagram of water electrolysis being conducted in an alkaline electrolyser (left) and a polymer electrolyte
membrane electrolyser cell (right) to produce hydrogen and oxygen from water and DC electricity This figure was originally
produced by Carmo et al 20138
49
Figure 38 A schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell that produces hydrogen and
oxygen from water and DC electricity the reactions that occur at the electrodes are also shown This figure was adapted
from Meng Ni et al 20085
Explanations
Alkaline water electrolysis has been a mature technology for over 100 years (there were over 400 units in
operation by 1902) They have high efficiencies (47-82) and long lifetimes (15 years)1186
A recent
publication by Ursuacutea et al 2012 compiled a list of the main manufacturers of alkaline water electrolysers which
is shown in Table 3211
A number of advancements have been made regarding alkaline electrolysers over the last few years which
have focused on improving their efficiency to reduce operating costs and have increased the operating
current densities11
Other advancements include
Minimising the space between the electrodes to reduce the ohmic losses and allow the cell to operate at
current densities
Developing new materials to replace older diaphragms which exhibit higher stability and are better at
facilitating ion transport
Developing high-temperature (ca 150 oC) alkaline water electrolysers to increase the electrolyte
conductivity and promote the kinetics of the electrochemical reactions at the electrodesrsquo surface
Developing new electrocatalytic materials to reduce the electrode over-potentials this present a particular
difficulty for the anode because the oxidation half-reaction is most demanding
Alkaline electrolysers (Figure 3 left) consist of two electrodes that are separated by a gas-tight diaphragm
submersed in an electrolyte solution containing a high concentration of potassium hydroxide (20-30 wt) It
should be noted that electrolytes such as sodium hydroxide and sodium chloride can also be used in some
systems and they usually operate between 40-90 oC
11 Water is reduced at the cathode to generate hydrogen
gas and hydroxide ions (OH-) which diffuse through the diaphragm to the anode where they recombine to
generate oxygen and water811
The hydrogen and oxygen produced by alkaline electrolysers have purities
gt99
In PEM electrolysers (Figure 3 right) the electrolyte is constructed from a polymeric membrane with a cross-
linked solid structure permitting a compact system with greater structural stability (able to operate at higher
temperatures and pressures)8 The electrodes used in PEM electrolysers are usually constructed from noble
metals such as platinum and iridium which limits the scope of this technology as noble metals are of limited
abundance and expensive The unit consisting of the electrodes and polymer membrane is submersed in
water Water oxidation occurs at the anode where oxygen is formed and protons are transferred through the
50
polymer membrane to the cathode where they are reduced to hydrogen PEM electrolysers are able to
produce hydrogen and oxygen of even higher purity than alkaline electrolysers at ca 9999
It should be noted that the materials needed for the electrolyte and electrodes have to be cheap and easy to
manufacture on a large scale5 Water in the gas phase diffuses into the porous cathode where it dissociates
into hydrogen and oxygen at reaction sites81
At this point the hydrogen diffuses out of the cathode and is
collected The oxygen ions are transported through the electrolyte solution to the porous anode where they
are oxidised to oxygen and collected this process is demonstrated in Figure 35 The material chosen for the
cathode has to be able to support the diffusion of steam the reduction of steam and the diffusion of hydrogen
These requirements limit the number of suitable materials that can be used to noble metals such as platinum
and gold and non-precious metals such as copper and nickel However like the artificial photosynthetic
systems previously discussed the use of noble metals is unfavourable due to their rarity and high costs The
anode has to be chemically stable under similar conditions to the cathode which means that noble metals are
again candidate materials along with electronically-conducting mixed oxides5
Electrolyte This must be a chemically stable dense gas-tight material with good ionic conductivity and
low electronic conduction The electrolyte has to be stable enough to withstand the high temperatures
associated with the chemical reactions taking place It has to be gas-tight to limit the recombination of
protons and O- to hydrogen and oxygen respectively The electrolyte should also be as thin as possible so
as to minimise the ohmic overpotential5
Electrodes It should be noted that the following properties are the same for both the anode and cathode
The electrodes have to be porous enough to allow the transportation of hydrogen and oxygen and need to
have a similar thermal expansion coefficient to the electrolyte so as to limit the amount of mechanical
stress the components exert on each other They must also be chemically stable in highly
oxidisingreducing environments and high temperatures5
To ensure that the SOEC is operating at its maximum efficiency a number of parameters need to be
quantified this is often done through modelling the system Some of the parameters measured include the
composition of the cathode inlet gas cathode flow rate and cell temperature39
When generating syngas in a
SOEC the carbon dioxide is fed into the cathode side of the device where the hydrogen is generated
51
Table 32 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the performance data for each device This table was originally constructed by Ursua et al 201211
Manufacturer
Technology
(configuration)
Production
(Nm3h)
Rated Power
(kW)b
Energy
Consumption
(kWhNm3)c
Efficiency
()d
Maximum
Pressure
H2 purity
(vol)
Location
AccaGen Alkaline (monopolar) 1-100 67-487 6-487 528-727 10 999 Switzerland
Avalance Alkaline (bipolar) 04-36 2-25 543-5 652-708 448 na USA
Claind Alkaline (bipolar) 05-30 na na na 15 997 Italy
ELT Alkaline (bipolar) 3-330 138-1518 46-43 769-823 1 998-999 Germany
ELT Alkaline (bipolar) 100-760 465-3534 465-43 761-823 30 993-998 Germany
Erredue PEM (bipolar) 06-213 36-108 6-51 59-698 25-4 993-998 Italy
Giner Alkaline (bipolar) 37 20 54 655 85 na USA
Hydrogen Technologies Alkaline (bipolar) 10-500 43-2150 43 823 1 999 Norway
Hydrogenics PEM (bipolar) 10-60 54-312 54-52 655-681 10 999 Canada
Hydrogenics Alkaline (bipolar) 1 72 72 492 79 9999 Canada
H2 Logic Alkaline (bipolar) 066-4262 36-213 545-5 649-708 4 993-998 Denmark
Idroenergy Alkaline (bipolar) 04-80 3-377 75-471 472-752 18-8 995 Italy
Industrie Haute Technology Alkaline (bipolar) 110-760 5115-3534 465-43 761-823 32 998-999 Switzerland
Linde Alkaline (bipolar) 5-250 na na na 25 999 Germany
PIEL division of ILT Technology Alkaline (bipolar) 04-16 28-80 7-5 506-708 18-8 995 Italy
Proton OnSite PEM (bipolar) 0265-30 18-174 73-58 485-61 138-15 99999 USA
Sagim Alkaline (bipolar) 1-5 5-25 5 708 10 999 France
Teledyne Energy Systems Alkaline (bipolar) 28-56 na na na 10 99999 USA
Tredwell Corporation PEM (bipolar) 12-102 na na na 75 na USA
52
332 Current status review of the state of the art
This section will focus on the advancements that have recently been made in regards to SOECs Much of the
research being conducted on SOECs is focused on increasing the efficiency and stability of the electrolyte and
electrodes by changing the temperature the SOECs operate at gas mixtures and the materials the cells are
constructed from
The most common electrolyte material used in SOECs yttria-stabilised zircona (YSZ) due to it having a high
thermal stability high oxygen ion conductivity and low cost To generate YSZ zirconia (ZrO2) can be doped
with compounds such as Y2O3 and Yb2O3 to improve the stability and conductivity Sc2O3 can also be used to
generate scandia-stabilised zirconia (ScSZ) Other co-dopants such as TiO2 and Al2O3 can be added to
further enhance the stability587
Scandium stabilised zirconia (ScSZ) has a higher conductivity than YSZ but
is not as widely used due to the high costs associated with it It should also be noted that the dopant
concentration has to be of a specific amount in order to ensure the conductivity is at its maximum It has been
shown that different dopant concentrations change the lattice structure of the ZrO2 over time which leads to
the decrease in conductivity5 The dopant chosen for the SOEC is also dependent on the temperature the cell
will have to operate at as the dopant will change the conductivity of the electrolyte at different temperatures
Researchers recently investigated the effect temperature (550 oC ndash 750
oC) had on the performance of SOEC
cells with the following layout a Ni-YSZ support layer (680 microm) a Ni-ScSZ cathode-active layer (15 microm) a
ScSZ electrolyte layer (20 microm) and a LSM-ScSZ anode layer (15 microm) The performance of the cell was
observed to decrease with decreasing temperature when the same gas composition was used (143 CO
286 H2O and 571 Argon) As the temperature decreased the ionic conductivity of the electrolyte layer
decreased The mass transfer was the rate-determining step for the electrodes at temperatures lt750 oC
Methane was only detected in the gas products when the input gas composition was the same as above the
cell temperature was lt700 oC and the operating voltage was gt 2 V
81 (TRL 3)
Electrolyte materials such as ceria- and LaGaO3-based electrolytes are showing promise at intermediate
temperatures when they are doped with other compounds that increase their ionic conductivity79
Recently
researchers developed SOEC capable of steam and carbon dioxide co-electrolysis The cell was constructed
from Ni-YSZ (nickel-yttria-stabilized zirconia) solid oxide cell with a bi-layered ScSZGDC electrolyte structure
and a LSCF (lanthanum strontium cobalt ferrite) oxygen electrode When the device was operated at 800 oC
the cell exhibited a high electrolysis current density of about 22 A cm2 and 19 Acm
2 in steam and carbon
dioxide electrolysis respectively The structural integrity of the cell was checked after the experiment and no
cracking or delamination of the electrolyte or the electrolyteelectrode was observed88
(TRL 4)
Researchers were recently able to directly synthesise methane by co-electrolysing carbon dioxide and water
to form carbon monoxide and hydrogen then conducting Fischer-Tropsch synthesis in tubular solid oxide
electrolysis cells7 As previously discussed the reduction of water in SOECs requires very high temperatures
(ca 800 oC) however with the Fischer-Tropsch process lower temperatures (ca 250
oC) are required Using
the experimental setup shown in Figure 3 researchers were able to achieve a methane yield of 1184
which means that 41 of carbon dioxide is converted to methane over the course of the 24-hour test7 The
equipment consists of a SOEC tube with a hole running through its length while the wall of the tube consists
of three layers that are structured in a similar fashion to that shown in Figure 3 it consists of an anode an
electrolyte and a cathode The first section of the SOEC tube is heated to 800 oC to allow syngas to be
generated after which the tube cools over a gradient to 250 oC to allow methane production to take place
(TRL 4)
53
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis cell electrolysers This table
was originally constructed by Carmo et al 20138
Alkaline Electrolysis PEM Electrolysis SOEC Electrolysis
Advantages
Well-established technology High current densities Efficiency up to 100
Non-noble metal catalysts High voltage efficiency Efficiency gt 100
Long-term stability Good partial load range Non-noble metal catalysts
Relative low cost Rapid response system High pressure operation
Stacks in the megawatt range Compact system design
Cost effective High gas purity
Dynamic operation
Disadvantages
Low current densities High cost of components Laboratory stage
Crossover of gases Corrosive environment Bulky system design
Low partial load range Low durability Low durability
Low dynamics Stacks below megawatt range Little costing information
Corrosive electrolyte
Figure 39 A schematic diagram of co-electrolysis and the Fischer-Tropsch process being conducted in a tubular solid oxide
electrolyser that is able to produce CH4 This figure was originally generated by Chen et al 20147
333 Patents
The cell was composed of separate anode and cathode chambers separated by a membrane that allows the
transport of sodium ions (Na+) the anode and cathode chambers are in contact with water Oxygen is
collected in the anode chamber and hydrogen is collected in the cathode chamber following which hydrogen
and carbon dioxide are reacted together to generate syngas and oxygen as by-products that need to be
separated The electrode materials were described as being ceramic that could be doped with a catalyst
material such as cobalt cerium europium or cadmium combinations of these elements were also permitted89
(TRL 3)
A patent was filed in 2011 detailing a design for SOEC that could co-electrolyse steam and carbon dioxide to
produce syngas The cell consisted of a cathode composed of nickel-zirconia an anode consisting of
strontium doped lanthanum manganite and the electrolyte between the two electrodes was composed of
yttria-stabilised zirconia the whole cell was designed to operate between 800-1000 oC The authors stated
that the electrical power to run the device would be sourced from nuclear power however it should also be
possible to run this device off solar energy This device operated with the carbon dioxide being fed into the
cathode section where the hydrogen is generated90
(TRL 4)
54
A patent was filed in 2013 detailing a modified anodeelectrolyte structure for a solid oxide electrochemical
cell where the role of the anode is to react with fuel (steamhydrocarbons) The cathode (when in SOEC
mode) consisted of a backbone of electronically conductive perovskite oxides selected from the group
consisting of niobium-doped strontium titanate vanadium-doped strontium titanate and tantalum-doped
strontium titanate mixtures were also permitted The electrolyte material consisted of a scandia and yttria-
stabilised zirconium oxide91
(TRL 2-3)
334 Future development main challenges
Technologies that are capable of electrolysing water cover a variety of TRLs wherein alkaline and PEM
electrolysers used to generate hydrogen by the water-splitting reaction have TRLs 7-8 as they have been
commercialised can be purchased and can produce power at the low megawatt scale However they are
currently not a viable option to generate power at the megawatt scale Newer SOEC technologies currently
being developed have lower TRLs (3-5) but are showing great promise in that their efficiencies are high and
they are cheap to produce
Technologies capable of co-electrolysing water and carbon dioxide to syngas are at an early stage of
development - TRLs 2-4 Research is still focused on studying how cell conditions can be manipulated to
optimise the production of syngas and hydrocarbons Research is also focused on improving the long-term
stability of the electrolytes and electrodes used in SOECs by investigating new materials and cell designs that
are cheap and easy to construct It will also be necessary to conduct duration experiments In terms of their
commercial viability they are far behind PVs at roughly the same stage as PEC technologies and ahead of
synthetic biology systems
SOECs could prove to be an efficient method by which electrical energy generated from renewable sources
(wind and solar) could be stored in the form of chemical bonds To date it has been proven that syngas can
be generated from SOECs and that methane can also be generated within the same system through a
Fischer-Tropsch process More research is needed that aims to improve the efficiency by which methanol can
be generated and to determine whether more complex hydrocarbons can be synthesised
The success of this technology is likely to be dependent on how well systems that generate electricity from
renewable sources can be integrated within it It has been suggested that nuclear wind and solar power
stations could be used to provide the electrical power required This would help to lower the cost of this
technology as sourcing the electricity needed is one of the major costs It should be noted that one of the
most commonly cited advantages of this technique over solar and wind power is that it is not site-specific
However if solar and wind power were to be used to generate the electricity needed for this technology then
it becomes a site-specific technology again This is also a problem for PEC-cell-based technologies
34 Summary
The aim of this brief literature review was to highlight the advancements that have been made across the main
technologies within artificial photosynthesis discuss some of the most recent technological solutions that have
been developed in these areas and identify the main challenges that need to be addressed for each
technology before they can be commercialised
Synthetic biology amp hybrid systems
Synthetic biology amp hybrid artificial photosynthetic systems are currently capable of producing small amounts
of fuel molecules such as hydrogen and simple hydrocarbons The majority of the technologies in this
category are at the research and development stage (TRL 1-4) To date there are no large scale plans to
produce solar fuels at a commercial level using this technology It should be noted that synthetic biology amp
hybrid systems are currently used to produce fine chemicals at the commercial level but these are not needed
55
in the large quantities in which solar fuels are required It is currently too early to comment on the long-term
commercial viability of this technological pathway however the research in this area is progressing quickly
and as our fundamental understanding of biological systems increases progression is promising It should be
noted that these systems are becoming efficient enough to produce hydrogen at a rate that is comparable to
that which occurs in natural photosynthesis on a small laboratory scale
Photoelectrocatalysis of water (water splitting)
PVssemiconductors are the most advanced technology discussed in this report as they have been
commercialised and are able to generate electricity on a MW scale at facilities such as the Solar Star Power
Station and the Topaz Solar Farm31
PVssemiconductors are used in PEC technologies where they are
incorporated into the cell design and act as light absorbers Instead of the energy gained from light absorption
being used to generate electricity directly it is used to generate fuel molecules such as hydrogen from the
water-splitting reaction The hydrogen generated from this process can then be stored and used at a later time
to provide energy This is useful because PVs are only able to generate power intermittently during daylight
hours There are many examples of photoelectrocatalysis being carried out by PECs as well as suspensions
of photoactive nanoparticles and the majority of the technologies have a TRL 2-4 However it should be noted
that PVsemiconductor technologies that generate electrical power have TRL 8-9 The main challenges facing
this technology involve developing materials that have high STH efficiencies are cheap to manufacture and
are stable for long periods of time Calculations have been performed to determine the efficiencies associated
with multiple reactor plant designs These have shown that it is theoretically possible to generate large
quantities of hydrogen however that it could cost trillions to generate a significant amount of hydrogen with
current technology
Co-electrolysis
Water electrolysers such as alkaline and PEM electrolysers are considered mature technologies that have
been commercialised and have TRLs 7-8 They can be purchased and can produce power at the low
megawatt scale However they are currently not a viable option to generate power at the megawatt scale
Newer SOEC technologies that are currently being developed have lower TRLs 3-5 but are showing great
promise in that their efficiencies are high and they are cheap to produce Technologies that are capable of
generating syngas and some organic products by a Fischer-Tropsch process are in the research and
development stage (TRL 3-4) Research is currently focused on determining how SOEC conditions can be
manipulated to increase efficiency as well as identifying more stable durable and efficient compounds to
incorporate into the cell design The incorporation of SOECs into large scale solar and wind farms could prove
to be an efficient method by which electrical energy can be stored as chemical energy
The technologies discussed above show great potential in being able to convert solar energy into solar fuels
They are still in the early research phase but all technologies made significant improvements in efficiencies
lifetimes and the number of products they can produce other than hydrogen It is likely that PVs will be used to
absorb solar energy to generate electricity for SOECs or forms part of a PEC cell that generates fuel
molecules It should be noted that wind power could be used to provide the electricity needed for SOECs to
operate which would allow these systems to be used outside of desert regions Biological systems currently
look to be less suitable for producing large quantities of fuel molecules partly due to their early research stage
but may prove to be useful in generating highly complicated molecules once the understanding of protein
engineering has increased
All of these technologies seek to improve device lifetimes increase efficiency lower manufacturing costs and
increase the scope of synthetic fuels that can be produced Switching to a hydrogen economy will require
large and expensive infrastructure changes Using hydrogen to generate more complex fuel molecules will
require more research however ultimately fewer infrastructure changes
57
4 Mapping research actors
41 Main academic actors in Europe
In Europe research on AP is conducted by individual research groups or in research networks or consortia
Most of the research groups are located in Germany the Netherlands and Sweden The largest country-based
networks are also in Sweden and in the UK Most of Germanyrsquos research groups are part of the pan-European
AP network AMPEA The number of research groups has increased substantially since the 1990s when the
field became more prominent coupling with the (exponential) rise of publications in AP3
411 Main research networkscommunities
In this section we describe the main research networkscommunities on artificial photosynthesis in Europe
Under networks we indicate co-operations with multiple universities research organisations and companies
Instead of focusing strictly on major integrated research on specific AP topics the networks mostly have a
broad research and collaboration focus Larger joint programmes exist but are more focused on various key
priorities in Europe for different research areas such as AMPEA (Advanced Materials and Processes for
Energy Application) which is one of the joint programmes of EERA (European Energy Research Alliance) of
which artificial photosynthesis is one of the three identified applications The first national research network
dedicated to artificial photosynthesis was the Swedish Consortium for Artificial Photosynthesis (CAP)
following which a number of other national and pan-European networks emerged in the past few years
Research networks and communities play an important role in facilitating collaboration across borders and
among different research groups The development of AP processes needs expertise from molecular biology
biophysics and biochemistry to organometallic and physical chemistry Research networks provide the
platform for researchers and research teams from those diverse disciplines to conduct research together to
create synergistic interactions between biologists biochemists biophysicists and physical chemists all
focusing on questions relevant for AP and solar fuels This need for research coordination is reflected by the
fact that the Swedish Consortium for AP was a bottom-up initiative by university-based scientists4
Furthermore networks are effective for promoting AP research and raising public awareness and knowledge
about AP5
Networks and consortia with industrial members also play an important role with respect to the goal of turning
successfully developed AP processes into a commercially viable product Research and innovation in
materials and processes of AP can be backed up by private innovation and investments Feedback on the
applicability of research outputs can be incorporated and shape further research efforts and application
possibilities in the business sector can be discovered
The advantages and synergy effects of network membership for research groups are reflected in the fact that
more than 50 of European research groups are part of a research network in Europe The consortia vary in
their membership and their funding sizes whereas about 400 researchers are affiliated with the pan-European
consortium AMPEA the Swedish CAP unites about 80 scientists Furthermore it is apparent that only AMPEA
is a truly pan-European consortium member research groups come from various European countries such as
Austria France Czech Republic Germany Italy the Netherlands Norway Spain Sweden Switzerland and
3 V Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in
ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press) conducted a bibliometric analysis using key words related to the field of artificial photosynthesis showing that only a few papers were published before the 1990s reaching more than 900 publications in 2014
4 httpwwwsolarfuelse
5 httpsolarfuelsnetworkcomoutreach
58
the UK Most of the other consortia discussed below are based in a specific country which is reflected in their
affiliations among research groups
EU - AMPEA
The European Energy Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials
amp Processes for Energy Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging
Technologies and artificial photosynthesis became the first energy research subfield to be organised within
AMPEA The goal of this joint programme which was launched at the end of 2011 is to set up a thorough and
systematic programme of directed research which by 2020 will have advanced to a point where commercially
viable artificial photosynthetic devices will be under development in partnership with the industry Its goal to
boost research on a pan-European basis is reflected in the fact that to date more than 40 European scientific
institutions participate Many institutes in different Member States are associated with AMPEA (31 full
members for example CEA DIFFER TU Delft JKU Max Planck Institute)6 The research efforts of the
AMPEA participants aim at advancing all of the three identified pathways of artificial photosynthesis Due to
the low availability of efficient molecular catalysts based on earth-abundant elements the search for those
elements and the development of such catalysts constitute the early research focus
Italy ndash SOLAR-CHEM
In 2009 the universities of Bologna Ferrara and Messina founded SOLAR-CHEM the Italian inter-university
centre for the chemical conversion of solar energy7 Later on other universities in Italy also joined SOLAR-
CHEM The research efforts of the centre aim to foster research in solar fuels through a multidisciplinary
approach and coordination activities eg through the organisation of dedicated events and through short-term
exchanges of staff in the network
Netherlands ndash BioSolar Cells
The Dutch BioSolar Cells public-private partnership was established in 2010 BioSolar Cells is a cooperation
of 10 knowledge institutions such as Leiden University Delft University of Technology and the University
of Twente8 as well as 45 private industries
9 The programme is funded by FOMALWNWO the Dutch
ministry of Economic Affairs Agriculture and Innovation many companies and a number of Dutch universities
and research organisations The BioSolar Cells programme has three themes artificial photosynthesis
photosynthesis in cellular systems and photosynthesis in plants These three research themes are
underpinned by a fourth theme education and societal debate where educational modules are developed to
equip and inspire future researchers policy makers and industrialists and where the societal consequences
of new solar-to-fuel conversion technologies are debated10
Sweden - CAP
Founded in 1994 the Swedish Consortium for Artificial Photosynthesis carries out integrated basic
research with the goal to produce applicable outcomes such as fuel from solar energy and water Their
projects integrate two topics artificial photosynthesis in man-made systems to make hydrogen from sun and
water and photo-biological fuel production in living organisms They focus on photoelectrocatalysis as the
technology pathway yet are also building on their research on the principles of natural photosynthesis for
energy production A unique component in the consortium is hence the synergistic interactions between
biologists biochemists biophysicists and physical chemists all focusing on questions relevant for solar
fuels11
The academic partners come from Uppsala University Lund University and the KTH Royal
Institute of Technology in Stockholm
6 httpwwweera-seteueera-joint-programmes-jpsadvanced-materials-and-processes-for-energy-application-ampea
7 httpswwwsocchimitsitesdefaultfileschimindpdf2012_6_88_capdf
8 httpwwwbiosolarcellsnlover-biosolar-cellsnew_page_1html
9 httpwwwbiosolarcellsnlover-biosolar-cellsbedrijvenhtml
10 httpwwwbiosolarcellsnlonderzoek
11 httpwwwsolarfuelsesolar-fuels
59
UK ndash SolarCAP
The SolarCAP Consortium for Artificial Photosynthesis is a consortium of four UK academic research groups
funded by the Engineering and Physical Sciences Research Council The groups based in the Universities
of East Anglia Manchester Nottingham and York12
are specifically exploring the solar conversion of
carbon dioxide to carbon monoxide in tandem with the conversion of methane or alkanes to useful oxygen-
containing products such as alcohols They are exploring the second technological pathway of
photoelectrocatalysis
UK ndash Solar Fuels Network
Solar Fuels Network brings together academic and industrial researchers in solar fuels and artificial
photosynthesis It aims to develop an effective community of solar fuels researchers from both academia and
industry to raise the profile of the UK solar fuels research community nationally and internationally Through
this it aims to promote collaboration and co-operation with other research disciplines industry and
international solar fuels programmes and to contribute towards the development of a UK solar fuels
technology and policy roadmap The networkrsquos management team is based at Imperial College London and
is led by Prof James Durrant Partner organisations encompass the Royal Society of Chemistry the Energy
community of the Knowledge Transfer Network (KTN) the Solar Fuels Institute (SOFI) and the Foreign and
Commonwealth Officersquos Science and Innovation Network13
In other countries across Europe national initiatives have emerged in the last few years and more are
expected to in the future For example the Photoelectrochemistry Competence Center (PECHouse and
PECHouse2)14
under coordination of the Ecole Polytechnique Federale de Lausanne (prof Michael Graumltzel)
has been created in Switzerland while in France artificial photosynthesis is being researched by laboratories
of excellence (LabEx Arcane15
and LabEx Charmatt16
)
412 Main research groups (with link to network if any)
A list of the main research groups in Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire Artificial
Photosynthesis community Taking that into account the numbers presented below may provide an indication
of the AP research sector as a whole
Table 41 Number of research groups and research institutions in European countries
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Austria 1 1 15
Belgium 1 1 -
Czech Republic 1 1 -
Denmark 3 2 -
Finland 1 1 6
France 5 3 14
Germany 31 17 16
Ireland 1 1 7
Italy 5 5 29
Netherlands 28 9 18
Norway 1 1 -
12
httpwwwsolarcaporgukresearchgroupsasp 13
httpsolarfuelsnetworkcommembership 14
httppechouseepflchpage-32075html 15
httpswwwlabex-arcanefrencontentlaboratoires-excellence-arcane 16
httpwwwcharmmmatfrindexphp
60
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Spain 4 4 11
Sweden 13 5 17
Switzerland 5 5 10
UK 13 9 10
Total 113 65 15
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 66 main research institutions and universities working on artificial photosynthesis in Europe
Those research institutions contain 113 individual research groups with an average size of about 15
people17
The sizes of research groups can vary widely from for example 80 members of a research group at
Imperial College London to only two persons in the research group of Klaus-Dieter Weltmann at the Leibniz
Institute for Plasma Science and Technology The country with both the highest number of involved institutions
and research groups is Germany where 32 individual research groups in 17 research institutions are active
Germany is followed by the Netherlands with nine institutions and 28 research groups and by Sweden with
five institutions and 13 research groups Almost half (47) of the research groups focus on the second
pathway ie photoelectrocatalysis whereas 36 research the first pathway ie the usage of synthetic
biology and hybrid systems to produce fuel molecules and about 17 follow the third pathway in their
research which is co-electrolysis A bulk of the research in most countries is done on the second pathway
except for in Sweden and Finland which seem to specialize in exploring the first pathway Table 42 provides
an overview of some of the key statistics the number of research groups and research institutions in AP per
country and the number of research groups focusing on each of the three technological pathways
respectively
Table 42 Number of research groups per research area (technology pathway)
Country Total Synthetic biology
amp hybrid systems
Photoelectrocatalysis Co-electrolysis
Austria 1 1 1 0
Belgium 1 1 1 0
Czech Republic 1 0 1 0
Denmark 3 0 2 2
Finland 1 1 0 0
France 5 2 5 0
Germany 31 14 15 9
Ireland 1 1 1 0
Italy 5 0 5 0
Netherlands 28 12 17 9
Norway 1 0 1 0
Spain 4 2 3 1
Sweden 13 10 7 0
Switzerland 5 1 5 3
UK 13 8 5 1
Total 113 53 69 25
Source Ecorys
17
The average group size is derived from survey responses and available information on the websites of the groups
61
In the following section our findings have been illustrated by presenting some of the main research institutions
and their research groups
Germany - Helmholz Zentrum Berlin
The Institute for Solar Fuels of the HZB is led by Prof Roel van de Krol The institute pursues a strategy to generate
hydrogen via the second technology pathway they combine the energy conversion of light into electrical energy via
photonic stimulation of the semiconductor directly with the catalytic procedures on the electrolyte-electrode-interface for
the conversion into storable chemical energy (hydrogen) The generated hydrogen can then be stored by means of
already known methods (compressed gas liquid-H2 metal hydride conversion to methanol) Their approach combines
research and insights from photo-physics surface- and material chemistry photoelectrochemistry interface- and
surface sciences as well as system alignment18
Therefore they collaborate closely with the University of Messina in
Italy and the Leiden University in the Netherlands Moreover the HZB is also part of the European research network
AMPEA
Germany ndash Max Planck Institute for Chemical Energy
The Department of Biophysical Chemistry at the Max Planck Institute for Chemical Energy focus on the water-oxidizing
enzyme of oxygenic photosynthesis and hydrogenases Their research uses a variety of different physical techniques
to gain insight into enzymatic processes such as into photosynthetic water splitting and (bio)hydrogen production
which can be used for biomimetic chemistry ie to develop catalytic systems in energy research19
They hence focus
on the first and second technology pathways The Max Planck Institute for Chemical Energy also contributes to the
European research network AMPEA
The Netherlands - The Dutch Institute for Fundamental Energy Research
Part of the Netherlands Organisation for Scientific Research (NWO) the DIFFER institute has since its initiation in 2012
grown to an activity of about 65 Meuroyear (about 75 fte) all directed at the production of chemicalsfuels from electrons
and photons In particular as part of its solar fuels research DIFFER investigates the splitting of water into hydrogen
and oxygen using electricity and the reduction of carbon dioxide to carbon monoxide As they are located at TUe
campus in Eindhoven they can easily collaborate and share knowledge with universities universities of applied
sciences and industry The DIFFER institute also contributes to AMPEA
Sweden ndash Uppsala University
Various research teams at Uppsala University cover all three relevant technology pathways for artificial
photosynthesis20
Moreover in 2006 the Swedish Consortium for Artificial Photosynthesis (CAP) founded in 1994 by
three researchers from Uppsala University and one researcher from the University of Stockholm created a new
scientific environment at the Aringngstroumlm laboratory at Uppsala University becoming the base for this consortium
Switzerland ndash ETH Zurich
The Professorship of Renewable Energy Carriers21
performs RampD projects in emerging fields of renewable energy
engineering operates state-of-the-art experimental laboratories offers advanced courses in fundamentalapplied
thermal sciences and produces qualified scientists and engineers with expertise in renewable energy technologies
Regarding solar fuels they focus on solar splitting of H2O and CO2 via thermochemical Redox cycles which
corresponds to the third technology pathway of artificial photosynthesis They are partners in several EU projects
concerning solar-driven hydrogen production such as SOLARJET ndash Solar Production of Jet Fuel from H2O and CO2
and HYCYCLES ndash Solar Water-Splitting Thermochemical Cycle22
18
httpswwwhelmholtz-berlindeforschungoeeesolare-brennstoffeindex_enhtml 19
httpwwwcecmpgderesearchbiophysical-chemistryoverviewhtmlL=1 20
httpwwwkemiuuseresearchmolecular-biomimeticphotosynthesis 21
httpwwwprecethzch 22
httpwwwprecethzchresearchsolar-fuelshtml
62
UK ndash Imperial College London
The research of various research teams of the Imperial College London encompasses the first and second technology
pathways It ranges from research on the oxidising enzyme Photosystem II which has become the focus of attention
because cheap water-splitting catalysts are urgently needed in the energy sector to the development of
photoelectrodes and nanoparticles for solar-driven fuel synthesis based on water splitting of water into hydrogen and
oxygen Collaborations across the Imperial College London are complemented with co-operations across the UK as
part of the UK Solar Fuels Network with the Swiss Federal Institute of Technology in Lausanne (EPFL) UCL and
Cambridge University
The density of research group per country in Europe is presented schematically in Figure 41
Figure 41 Research groups in Artificial Photosynthesis in Europe
Source Ecorys
42 Main academic actors outside Europe
Also outside of Europe research on AP is conducted by individual research groups or in research networks or
consortia Most of the research groups and networks are located in the US and in Japan Whereas US-based
networks sporadically have ties to European research groups the Japanese consortia have exclusively
Japanese members both academic and industrial
421 Main research networkscommunities
Outside of Europe the main networks can be found in the US and in Japan The biggest network is the US
network JCAP (Joint Center for Artificial Photosynthesis) with more than 190 persons linked to the
programme and a budget of $122 million for five years Next in line is the Japanese ARPChem which has
roughly the same budget available for a time span of 10 years
63
Japan ndash ARPChem
The Japanese Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology jointly launched the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem) in November 2012 The aim is to bundle efforts for the next
decade to develop innovative catalysts and other materials that could be used for manufacturing fundamental
chemical substances from water and carbon dioxide by making use of solar power Such substances can be
used as raw materials of plastics synthetic fibres synthetic rubber solvents and other products and are
applicable in all areas of peoples everyday lives The expected budget for the coming decade between 2012
and 2021 amounts to 15 billion yen (euro 122 million)23
The utilisation of catalyst technology requires long-term
involvement and entails high risks in development but is expected to have a huge impact on Japans
economy and society The aim is to achieve independence from fossil resources used as raw materials for
chemical substances while overcoming resource and environmental challenges The consortium consists of
partners from academia industry and the government seven universities amongst them the University of
Tokyo the Tokyo University of Science and the Kyoto University companies such as Mitsubishi
Chemicals Mitsui Chemicals Fuji Films and TOTO and governmental research organizations such as the
National Institute of Advanced Industrial Science and Technology (AIST)
Japan ndash All Nippon Artificial Photosynthesis Project for Living Earth (AnApple)
The All Nippon Artificial Photosynthesis Project for Living Earth (AnApple) is one of the Scientific
Researches on Innovative Areas receiving strong financial support from the Ministry of Education Culture
Sports Science and Technology It was set up in 2012 as a five-year national project Although it is not a
consortium in a narrow sense its scope and research impact are substantial as more than 40 Japanese
leading scientific groups are part of this project It is led by Prof Haruo Inoue from the Tokyo Metropolitan
University further academic partners are amongst others the Tokyo University of Science the Tokyo
Institute of Technology Ibaraki University Ritsumeikan University and Hokkaido University
South Korea ndash KCAP
The Korean Centre for Artificial Photosynthesis (KCAP) was launched at Sogang University in 200924
set up
as a ten-year programme with 50 billion won (about euro40 million)25
It aims to secure a wide range of
fundamental knowledge necessary materials and device fabrication for the implementation of artificial
photosynthesis ie generating liquid fuel and oxygen from water and carbon dioxide using solar energy
through collaborative research with a number of research organisations and companies The Korean partners
comprise 14 professors from 8 universities including Sogang University Yonsei University and the Ulsan
National Institute of Science and Technology and one industry partner Pohang Steel Company26
Foreign academic partners are the Lawrence Berkeley National Laboratory California Institute of
Technology and University of California Berkeley The Centre has ties to other AP networks such as SOFI
and JCAP
US ndash JCAP
In 2010 the Department of Energy created the Energy Innovation Hubs and among them a Joint Centre for
Artificial Photosynthesis (JCAP) was established between the California Institute of Technology and the
Lawrence Berkeley National Laboratory in California27
JCAP draws on the expertise and capabilities of key
collaborators from the University of California (UCI and UCSD) and the SLAC National Accelerator Laboratory
operated by Stanford University The initial funds in 2010 amounted to $122 million JCAP is the largest
artificial photosynthesis network in the US with more than 190 persons linked to the programme The research
foci encompass electro-catalysis photo-catalysis and light capture materials integration and numerical
23
httpwwwmetigojpenglishpress20121128_02html 24
httpwwwk-caporkrenginfoindexhtmlsidx=1 25
httpwwwsogangackrnewsletternews2011_eng_1news12html 26
httpswwwicef-forumorgannual_2015speakersoctober8cs2appdfcs-2_20058_kyung_byung_yoonpdf 27
httpsolarfuelshuborgwho-we-areoverview
64
modelling test-bed prototyping and benchmarking The funds for the next five-year period (2016-2020)
amount to $75 million and are subject to congressional appropriation
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years Core members include the Northwestern University and
Uppsala University A process of exchanges is instituted which encompasses six different universities in four
countries Industry partners are ILampFS (India) Total (France) and Shell28
This list is not exhaustive and increasing interest in the field of artificial photosynthesis would certainly lead to
the launch of new national and international programmes
422 Main research groups (with link to network if any)
A list of the main research groups outside Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire AP
community outside of Europe We are confident however that it provides an accurate indication about the AP
sector outside of Europe
Table 43 Number of research groups and research institutions in non-European countries
Country Number of research groups Number of research institutions Average size of a
research group
Australia 1 1 18
Brazil 1 1 5
Canada 1 1 -
China 12 5 13
Israel 1 1 6
Japan 16 15 15
Korea 4 4 16
Singapore 1 1 14
US 40 32 18
Total 77 61 5
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 61 main research institutions or universities working on artificial photosynthesis outside of
Europe most of which are based in the US and in Japan Those research institutions contain 77 individual
research groups with an average group size of 8 people29
Yet the sizes of research groups can vary widely
from 26 members at the University of Tokyo to only two persons at Kobe University The country with both the
highest number of involved institutions and research groups is the US where 40 individual research groups in
32 research institutions are active Hence the US is a world leader in terms of research groups working on
AP Japan follows with 16 institutions and 15 research groups which lies below the numbers for Germany
and the Netherlands Almost 80 of the research groups (77) focus on the second pathway
(photoelectrocatalysis) whereas about 39 research the first pathway (synthetic biology amp hybrid
systems) The remaining 18 focus their activities on the third pathway (co-electrolysis) Table 44
28
httpwwwsolar-fuelsorgabout-sofi 29
The average group size is derived from survey responses For more information please refer to Annex I
65
provides an overview of some of the key statistics such as the number of AP research groups and institutions
per country and their respective focus on one of the three technology pathways
Table 44 Number of research groups per research area (technology pathway)
Country Technology
pathway
Total Synthetic biology
and hybrid systems
Photoelectrocatalysis Co-electrolysis
Australia 1 1 1 0
Brazil 1 0 1 0
Canada 1 0 1 1
China 12 4 6 2
Israel 1 1 0 1
Japan 16 7 15 1
Korea 4 0 4 0
Singapore 1 0 1 0
US 40 17 30 9
Total 77 30 59 14
Note a research group might focus on multiple technology pathways
Source Ecorys
In the following section our findings are illustrated by presenting some of the main research institutions and
their research groups
China ndash Dalian University of Technology
In 2011 the Dalian National Laboratory for Clean Energy (DNL) based at the Dalian Institute of Chemical Physics
(DICP) of the Chinese Academy of Sciences (CAS) was established It integrates research into clean energy and the
efficient use of fossil fuels to meet Chinas sustainable energy development strategy It is led by Li Can
Israel - Weizmann Institute of Science
To meet the challenge of providing clean sustainable energy the Weizmann Institute has established the Alternative
Sustainable Energy Initiative (AERI) The goal of this initiative is to create the conditions conducive to alternative
energy research and to identify promising avenues of research With the help of AERI the Weizmann institute hopes to
encourage its scientists to conduct basic research relevant to the future development of alternative sustainable energy
and to nourish the next generation of scientists in this field around the world in Israel and at the Weizmann Institute
The researchers at the Weizmann Institute of Science and at AERI preliminarily focus on the third pathway
Japan ndash University of Tokyo
The Domen Laboratory at the University of Tokyo is a research group focused on the second technological pathway
Their challenge is to find out novel photocatalysts that effectively work on water splitting under visible light by studying
different new materials
US ndash Arizona State University
The multidisciplinary team of the Center for Bio-inspired Solar Fuel Production of the Arizona State University aims to
design a complete system for solar water oxidation and hydrogen production Therefore they are focusing on five
specific subtasks (i) The total system analysis of the solar water-splitting device (ii) water oxidation (iii) fuel
production (iv) the artificial reaction center-antenna which relates to light collection and (v) the development of
functional nanostructured transparent electrode materials Their focus lies hence on the first and second AP technology
pathways
The density of research groups per country in the world is presented schematically in Figure 42 Please note
that in this figure (as opposed to Figure 41) we do not count each European country individually but
aggregate the numbers for all of Europe
66
Figure 42 Research groups active in the field of AP globally
Source Ecorys
43 Level of investment
In this section the level of investment is discussed in further detail The level of research investment in the EU
is based on the total budget of the projects whenever available In addition information is given on the time
period of the research projects
Information on the investment related to or funding of artificial photosynthesis research programmes and
projects at the national level is generally difficult to find especially for academic research groups Most budget
numbers found relate to the budget of the institution andor the (research) organisation in general and are not
linked to specific artificial photosynthesis programmes in particular unless the institute or research
programme is completely focused on artificial photosynthesis
Table 45 presents an overview of the investments made by a number of organisations
Table 45 Investments in the field of artificial photosynthesis
Country Organisation Budget size Period
Research investments in Europe
EU European Commission (FP7 and previous
funding programmes) euro 30 million 2005 - 2020
France CEA euro 43 billion 2014 covers not only AP
Germany
German Aerospace Centre (DLR) and the
Helmholtz Zentrum euro 4 billion
Annual budget covers
not only AP
Germany
Max Planck Institute for Chemical Energy
Conversion euro 17 billion 2015 covers not only AP
Germany
BMBF ldquoThe Next Generation of
Biotechnological Processesrdquo euro 42 million 2010 - present
Germany Government of Bavaria euro 50 million
2012-2016 covers not
only AP
Members of AMPEA AMPEA (EERA) euro 60 million 2010 - present
Netherlands Biosolar Cells euro 42 million 2010-present
Sweden Consortium for Artificial Photosynthesis euro 118 million 2013
UK SolarCAP and other initiatives in UK euro 92 million 2008-2013
67
Country Organisation Budget size Period
UK
University of East Anglia Cambridge and
Leeds euro 1 million 2013
Research investments outside Europe
China Dalian National Laboratory for Clean Energy euro 40 million Annual budget since
2011
Israel AERI euro 13 million 2014-2017
Japan ARPChem euro 122 million 2012 - 2021
Korea KCAP euro 385 million 2009 - 2019
UK US Plug-and-play photosynthesis euro 44 million 2014 - 2017
US JCAP euro 175 million 2010 - 2020
US SOFI euro 1 billion 2012 - 2022
Source Ecorys
431 Research investments in Europe
In Europe national researchers research groups and consortia are generally funded by European funds (such
as the ERC Grant from the European Commission) national governments businesses and universities In this
section special attention is paid to the EU FP7 projects These projects are mainly funded by European
contributions Further information is provided on AMPEA BioSolar Cells CAP SolarCap and some other AP
initiatives
Investments range between euro10 million for the national consortia (UK - SolarCap and Sweden - CAP) and euro42
million for the Dutch consortium to smaller budgets for local projects The projects at the European level are
more extensive The funds for all twenty FP7 projects related to artificial photosynthesis amount to a total
value of euro30 million AMPEA consists of around 400 professionals and an investment of approximately euro60
million contributed by the participants and associates themselves
Funding of AP research programmes and research consortia
EU ndash FP6 and FP7 projects
The FP6 and FP7 projects (6th
and 7th Framework Programmes for Research and Technological
Development) were undertaken in seven years between 2002 and 2013 and had a total budget of over euro60
billion30
Within FP7 around two thirds of the overall budget was aimed for the Cooperation programme of
which energy is one of the ten key thematic areas Investment in energy research under EU FP7 has been
around euro25 billion Various projects on artificial photosynthesis solar-powered hydrogen production by means
of water splitting have been completed under the EUrsquos Seventh Framework Programme Projects include
inter alia Solhydromics Solar-H Directfuel and H20Split FP7 is the key tool to respond to Europersquos needs in
terms of jobs and competitiveness and to maintain leadership in the global knowledge economy31
The
successor programme of FP7 has a number of projects in the field of artificial photosynthesis For example
PECDEMO project32
aims to develop a hybrid photoelectrochemical-photovoltaic tandem device with a solar-
to-hydrogen efficiency of 8-10 This illustrates the trend to move from fundamental research of materials and
processes (that was the main focus in FP6 and FP7 programmes) to the development of prototypes to reach
higher TRL levels (that is the main focus in H2020 programme)
An overview of the EU FP6 and FP7 projects on AP is presented in the table below
30
httpseceuropaeuresearchfp6pdffp6-in-brief_enpdf httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 31
httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 32
httppecdemoepflchpage-113311-enhtml
68
Table 46 EU FP6 and FP7 projects on artificial photosynthesis
EU FP7 project Technology pathway Total budget EU contribution to
the total budget
Time
period
(months)
ARTIPHYCTION Photolectrocatalysis (Water Splitting ) euro 3594581 euro 2187040 36
DIRECTFUEL Synthetic Biology amp Hybrid Systems euro 4977781 euro 3729519 48
CO2PHOTORED Photolectrocatalysis (Water Splitting ) euro 176053 euro 176053 24
COFLeaf Photolectrocatalysis (Water Splitting ) euro 1497125 euro 1497125 60
EWOCS Photolectrocatalysis (Water Splitting ) euro 168896 euro 168896 24
FAST MOLECULAR
WOCS
Photolectrocatalysis (Water Splitting )
euro 100000 euro 100000 48
H2OSPLIT Photolectrocatalysis (Water Splitting ) euro 100000 euro 100000 48
HJSC Research for fundamental understanding euro 337094 euro 337094 36
NANO-PHOTO-
CHROME
Synthetic Biology amp Hybrid Systems euro 218731
euro 218731 17
HyMap Photolectrocatalysis (Water Splitting ) euro 2506738 euro 2506738 60
PCAP Photolectrocatalysis (Water Splitting ) euro 190800 euro 190800 36
PHOTOCATH2ODE Photolectrocatalysis (Water Splitting ) euro 1500000 euro 1500000 60
PHOTOCO2 Photolectrocatalysis (Water Splitting ) euro 50000 euro 50000 24
PS3 Synthetic Biology amp Hybrid Systems euro 1997944 euro 1997944 60
SOLAR-H Synthetic Biology amp Hybrid Systems euro 2316000 euro 1800000 36
SOLAR-JET Photolectrocatalysis (Water Splitting ) euro 3123950 euro 2173548 48
SOLHYDROMICS Synthetic Biology amp Hybrid Systems euro 3655828 euro 2779679 42
SUSNANO Catalysts can be either used for hybrid
systems or the water splitting category euro 100000
euro 10000 54
TRIPLESOLAR Photolectrocatalysis (Water Splitting ) euro 2493585 euro 2493585 60
light2hydrogen Photolectrocatalysis (Water Splitting ) euro 900000
Total euro 30005106 euro 24016752 821
Source FP7 Project list
In total euro30 million of which 80 were based on European contributions have been spent on 20 projects
related to artificial photosynthesis Most projects were completely funded by the European Union On average
the time period of these projects was around 43 months the shortest project lasting only 17 months and the
longest one 60 months Almost all funding related to the topics of photoelectrocatalysis (55) and synthetic
biology amp hybrid systems (44) Some additional funding was spent on research for fundamental
understanding (the HJSC project) and catalysts which are useful for either hybrid systems or water splitting
(the SUSNANO project)
Table 47 Total EU budget on artificial photosynthesis per technology pathway
Technology pathway TRL Total budget
Synthetic biology amp hybrid systems 1-2 euro 13166284
Photoelectrocatalysis (water splitting ) 1-4 euro 16401728
Catalysts that can be used for both categories above 1-4 euro 100000
Research for fundamental understanding - euro 337094
Total - euro 30005106
69
Based on the monthly funding of the FP7 projects33
it may be observed that annual investments in artificial
photosynthesis have been increasing over the years (Figure 43) There were no projects on artificial
photosynthesis in 2008 therefore no investments were made The highest investment was made in 2014 with
euro45 million spent on projects After that investments have been decreasing It is however expected that
from 2016 more projects on artificial photosynthesis will be conducted therefore investment will rise
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020
Note It is assumed that the funding of the projects is evenly distributed over months Thus annual expenditures are
calculated as a sum of the monthly expenditures Project lsquolight2hydrogenrsquo is excluded from the calculation since there is no
information available on the number of months the project is running
Source Ecorys
EU ndash AMPEA (EERA)
EERA is an alliance of leading organisations in the field of energy research comprising more than 150
participating organisations all over Europe The primary focus of EERA is to accelerate the development of
energy technologies to the point that they can be embedded in industry-driven research Activities of EERA
are based on the alignment of own resources while over time the Joint Programmes can be expanded with
additional sources including from Community programmes34
In EERA approximately 3000 FTE (equivalent
of 3000 professionals) are involved which makes for a budget of around euro450 million35
AMPEA is one of the
programmes under EERA focusing on AP in which roughly 400 professionals are involved This would then
make for an investment of approximately euro60 million for AMPEA
The Netherlands ndash BioSolar Cells
The total budget of BioSolar Cells is around euro42 million based on public and private funds The Ministry
contributed euro25 million the NWO (The Dutch organisation on Scientific Research) euro35 million and Dutch
universities and research centres around euro7 million Private organisations invested euro65 million The specific
research programme Towards Biosolar Cells in which the Delft University of Technology is involved is
being allocated a budget of euro25 million by the Dutch Ministry of Agriculture Nature and Food Quality A
benefit of funding partly by private funding is the focus on building infrastructure and retaining key
33
It is assumed that funding is spread evenly over the months that the project is being implemented This means that if a project is running 36 months with a total budget of euro1 million it is assumed that monthly investments are euro83000 (1 million 12) If a project started in May 2010 then investment over the whole year 2010 is calculated as 8euro83000 After annual investment is calculated for all projects yearly total investment is calculated as a sum across projects
34 httpssetiseceuropaeuimplementationtechnology-roadmapeuropean-energy-research-alliance-eera
35 httpwwwapreitmedia168877busuoli_eneapdf
70
researchers Public funding of artificial photosynthesis is mostly for the short term facilitating the entry of new
groups36
Swedish ndash CAP
The Swedish Consortium for Artificial Photosynthesis connecting the universities of Lund Stockholm and
Uppsala is chaired by Stenbjoumlrn Styring There are 80 persons linked to the consortium In 2013 the Swedish
Energy Agency distributed the amount of euro118 million (SEK 108 million) in total to lsquosome of Swedenrsquos best
research groupsrsquo Out of this amount euro87 million went to three research groups at Uppsala University euro37
million to research on artificial photosynthesis to generate solar fuels euro32 million for research on dye-
sensitised solar cells and euro18 million to research on thin film solar cells (TFSC) It is the largest one-time
investment in solar energy ever in Sweden37
The Swedish Consortium for Artificial Photosynthesis ndash Stenbjoumlrn Styring
The project Molecular Solar Energy Sciences is funded by the KampA Wallenberg Foundation with euro5 million The main
research activities related to artificial photosynthesis include mechanistic studies on synthetic molecular and
moleculesemiconductor systems for the light-driven reduction of protons and CO2 and oxidation of water Furthermore
research is conducted on cyanobacteria systems for photo-biological fuel generation synthetic biology molecular
biology and metabolic engineering A second project on artificial photosynthesis is funded by the Swedish Energy
Agency (euro4 million) An additional four projects are funded by Swedish and European sources with a total of euro5
million38
UK ndash SolarCAP and others
The Engineering and Physical Sciences Research Council (EPSRC) in the UK supports several AP-related
projects through the Towards a Sustainable Energy Economy programme39
The total amount of funding is
approximately euro92 million
New and Renewable Solar Routes to Hydrogen is led by Imperial College London and is targeting both
artificial and natural photosynthetic routes to solar-derived hydrogen (euro5 million)40
Artificial Photosynthesis Solar Fuels is led by the University of Glasgow (euro2 million)41
The SolarCAP consortium for Artificial Photosynthesis is a consortium of five UK academic research
groups (based at the Universities of East Anglia Manchester Nottingham and York) they are working to
develop solar nanocells for the production of carbon-based solar fuels (euro22 million)
Funding of other AP initiativesprojects
Germany ndash German Aerospace Centre (DLR) and the Helmholtz Zentrum
The Helmholtz Zentrum is Germanyrsquos largest scientific organisation with more than 38000 employees and an
annual budget of more than euro4 billion42
It consists of 18 scientific technical biological and medical research
centres The research institutes of the German Aerospace Centre (DLR) are affiliated with the Helmholtz
Zentrum One of the Institutes of DLR the Institute of Solar Research forms part of the Helmholtz Zentrum
programme for renewable energies This programme focuses on projects on cost reduction in solar thermal
power plants the thermo-chemical generation of solar fuels in the period 2015-2019 the solar tower in Juumllich
the bioliq pilot plant and the Gross Schoumlnebeck geothermal research platform43
Research institutes submit
their research projects for evaluation by an international panel in order to qualify for funding under the
Renewable Energies Programme based on the outcome the Helmholtz Zentrum makes funding
recommendations for a five-year period
36
httpbiomassmagazinecomarticles2883towards-biosolar-cells-program-receives-government-funding 37
httpwwwuuseennewsnews-documentid=2282amptyp=artikelamparea=2amplang=en 38
Information is based on the survey responds 39
httpwwwrscorgglobalassets04-campaigning-outreachrealising-potential-of-scientistsresearch-policyglobal-challengessolar-fuels-2012pdf
40 httpgowepsrcacukNGBOViewGrantaspxGrantRef=EPF00270X1
41 httpgtrrcukacukprojectsref=EPF0478511
42 httpwwwdlrdesfendesktopdefaultaspxtabid-888515347_read-37692
43 httpwwwhelmholtzdeno_cacheenresearchenergyrenewable_energies
71
Germany ndash The Max Planck Institute for Chemical Energy Conversion (MPI CEC)
The MPI CEC was founded in 2012 to focus on the issue of energy conversion Its researchers analyse the
basic processes of energy storage and conversion within three research departments which encompass 200
employees44
The MPI CEC is for the most part financed by public funds from both the German state and
regions The MPI CEC is part of the Max Planck Society for the Advancement of Science which is a formally
independent non-governmental and non-profit association of German research institutes The budget of the
entire society amounted to euro17 billion in 2015
Germany ndash Federal Ministry of Education and Research (BMBF)
In 2010 the BMBF launched the initiative ldquoThe Next Generation of Biotechnological Processesrdquo45
Part of this
initiative were deliberations directed toward simulating biological processes for material and energy
transformation A funding amounting euro42 million is available for the first 35 projects on microbial fuel cells
artificial photosynthesis and universal production46
Germany ndash SolTech (Solar Technologies Go Hybrid)
The Government of Bavaria initiated SolTech an interdisciplinary project to explore innovative concepts for
converting solar energy into electricity and non-fossil fuels The project brings together research by chemists
and physicists at five different Bavarian Universities and is funded with euro50 million for the period 2012-201647
The SolTech network covers all fields of research on solar energy use such as the conversion of solar energy
to electricity for immediate use and the conversion of solar energy into chemical energy for storage and future
use
France - Alternative Energies and Atomic Energy Commission (CEA)48
CEA is a public government-funded research organisation active in four main areas low-carbon energies
defence and security information technologies and health technologies The CEA is the French Alternative
Energies and Atomic Energy Commission The CEA had a total budget of euro43 billion and around 16000
permanent staff On photovoltaic cell technology CEA is collaborating with Photowatt Pechiney and Appolon
Solar and on photovoltaic modules and systems with TOTAL Energie
UK - University of East Anglia (UEA) Cambridge and Leeds
A specific research programme by the UEA on the creation of hydrogen with energy derived from
photocatalysts designed to replicate photosynthesis is funded by the Biotechnology amp Biological Sciences
Research Council (BBSRC) The total amount of funding is approximately euro1 million (pound800000)49
432 Research investments outside Europe
The main research programmes and consortia discussed are JCAP (US) SOFI (US) ARPChem (Japan)
AnApple (Japan) and KCAP (Korea) In contrast to Europe the use of energy innovation hubs ie major
integrated research centres drawing together researchers from multiple institutions and varied technical
backgrounds is more common in the US and Asia Also partnerships between the government academia
and industry seem to be more common in those areas than they are in Europe The idea of developing new
energy technologies in innovation hubs is very different compared to the approach of helping companies scale
up manufacturing through grants or loan guarantees50
The information on the budgets from the large
networks is generally available
44
httpwwwcecmpgdeinstitutdaten-faktenhtml 45
httpswwwbiotechnologiedeBIONavigationENrootdid=164934htmlview=renderPrint 46
httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf 47
httpwwwsoltech-go-hybriddeabout-soltech 48
httpenglishceafrenglish-portal 49
httpwwwwiredcouknewsarchive2013-0122artificial-photosynthesis 50
httpswwwtechnologyreviewcoms429681artificial-photosynthesis-effort-takes-root
72
Funding of AP research programmes and research consortia
Japan ndash ARPChem
In Japan the Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology (MEXT) launched a large artificial photosynthesis project that will tackle the study for
the coming decade between 2012 and 2021 with an expected budget of about euro122 million (15 billion yen)
The main organisation to conduct the project is the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem)51
Japan ndash AnApple
All Nippon Artificial photosynthesis Project for Living Earth (AnApple) is a five-year research programme
(2012-2017) joined by more than 40 Japanese leading scientific groups In this strong collaboration they aim
at achieving breakthroughs for the realisation of artificial photosynthesis AnApple hosted The International
Conference on Artificial Photosynthesis (ICARP)rdquo in 2014 and receives strong financial support52
from the
Ministry of Education Culture Sports Science and Technology
Korea ndash KCAP
The Korea Center for Artificial Photosynthesis (KCAP) at Sogang University was established in September
2009 through complementary and collaborative research with the Lawrence Berkeley National Lab (LBNL) in
the US to build the foundation for the realisation and commercialisation of artificial photosynthesis KCAP
receives a grant of euro385 million (50 billion won in 10 years) from the Ministry of Education Science and
Technology (MEST) through the National Research Foundation of Korea (NRF)
US - JCAP
JCAP (Joint Centre for Artificial Photosynthesis) was established in 2010 by the Department of Energy as one
of the Energy Innovation Hubs with a fund of euro108 million ($122 million) for five years Additional funding for
the next five years amounts to euro67 million ($75M) but is still subject to congressional appropriation53
JCAP
is the largest artificial photosynthesis research programme in the world There are 190 persons linked to the
research programme
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years SOFI (Solar Fuels Institute) is focused on light capture
water splitting CO2 catalysis and photoelectrochemical cells SOFI relies on a community of member
institutions and individual supporters who believe strongly in a clean energy future54
The solar fuel created
using catalysts and technology shared by global members of SOFI is funded by crowdfunding campaigns
(Kickstarter campaign) Furthermore SOFI partnered with TSRC to raise by means of a bold campaign one
billion dollars over the next ten years to fund the research55
Funding of other AP initiativesprojects
US ndash Plug-and-play photosynthesis CAPP (combining algal and plant photosynthesis)
Three UKUS-funded projects received funding to improve photosynthesis The three research teams (each
comprised of scientists from the United Kingdom and the United States) have been awarded a second round
of funding to build on their research findings and develop new ways to improve photosynthesis Projects
include plug-and-play photosynthesis by the Arizona State University Multi-level Approaches for Generating
Carbon Dioxide (MAGIC) led by the Pennsylvania State University and Combining Algal and Plant
Photosynthesis (CAPP) led by the Stanford University received in 2014 a new round of funding of euro44 million
51
httpwwwmetigojpenglishpress20121128_02html 52
httpartificial-photosynthesisnetICARP2014scopehtml The concrete funding figures are not available 53
httpenergygovarticlesenergy-department-provide-75-million-fuels-sunlight-hub) httpsolarfuelshuborgresearchoverview 54
httpwwwsolar-fuelsorgdonate 55
httpstelluridescienceorgsofi-brochurepdf
73
(pound5 million) in total over three years from the Biotechnology and Biological Sciences Research Council
(BBSRC) and the National Science Foundation56
Israel ndash Projects funded by AERI
AERI is providing a pool of funds to try out new ideas and jump-start research projects that are not applicable
for conventional grants Since 2006 already 8 cycles of AERI-funded projects took place Projects under the
20132014 cycle include lsquoNew Options for Solar Energy Conversion to Biofuel and Electricity ndash Biofuels ndash
Photovoltaics and Opticsrsquo57
Funding is provided by the Canadian Center for Alternative Energy Research the
Helmsley Energy Program the Helmsley Charitable Trust (providing euro13 million ($15 million) over three
years) the Burk Fund for Alterative Energy Studies the Eisenberg Foundation and individuals58
China ndash Funding of the Dalian National Laboratory for Clean Energy
The Dalian National Laboratory for Clean Energy was established in 2011 The investments into this lab
amount to more than euro40 million (289 million RMB) a year (over 50 of annual research of the Dalian
University of Technology within which the laboratory functions)59
In addition to this laboratory Haldor Topsoe
opened an RampD Center60
at the same university to join forces in the research of clean energy Haldor Topsoe
is also going to sponsor RampD projects however the size of the investments is not revealed Prior to that
Topsoe already established a scholarship with a value of around euro400 a month (3000 RMB)61
44 Strengths and weaknesses
This section presents the analysis of the strengths and weaknesses of the research community in the field of
artificial photosynthesis The findings are based on the results of the survey conducted during March 2016
and are supplemented by desk research Firstly we outline the main strengths and weaknesses with regard to
global AP research Secondly the strengths and weaknesses of the European community compared to the
non-European community are presented
441 Strengths and weaknesses of AP research in general
Table 48 below summarises the strengths and weaknesses of research in AP taking a global perspective
Table 48 Summary of strengths and weaknesses of research globally
Strengths Weaknesses
A diverse community of researchers bringing together
experts in chemistry photochemistry electrochemistry
physics biology catalysis etc
Researchers focus on all technology pathways in AP
Existing research programmes and roadmaps in AP
Available financial investments in several countries
Limited communication cooperation and collaboration
at an international level
Limited collaboration between academia and industry
at an international level
Transfer from research to practical applications is
challenging
Note International level refers not only to EU countries but all around the world
Globally there is a wide variety of RampD institutes (and researchers) focused on AP forming a diverse
community of researchers Research in AP requires interdisciplinary teams The experts working together
on this topic often have backgrounds in chemistry physics and biology
56
httpwwwbbsrcacuknewsfood-security2014140602-pr-bbsrc-and-nsf-funding-photosynthesis 57
httpwwwweizmannacilAERIresearch 58
httpwwwweizmannacilresdevsitesweizmannacilresdevfilesenergy_booklet_lo_res_2012pdf 59
httpwwwnaturecomnews2011111031fullnews2011622html 60
httpwwwtopsoecomnews201602topsoe-establishes-rd-center-dalian-institute-chemical-physics-china 61
httpwwwdnlorgcnshow_enphpid=776
74
A diverse community of researchers is focusing on all the pathways in AP which ensures diverse
approaches an exchange of different views a dynamic research community and avoids lock-ins into one
specific pathway This broad and inclusive research approach is the best way to maximise the probability of
AP research being successful in developing efficient and commercially viable AP processes
Several countries have dedicated programmes andor roadmaps to the topic of AP The US Japan the
Netherlands and South Korea have invested in large-scale interdisciplinary research programmes (specifically
on solar fuels) China and Japan have dedicated centres for renewable energy research where solar fuels are
an area of substantial effort For example the Department of Energy of the US sponsors Energy Innovation
Hubs aiming to overcome scientific barriers to develop a complete energy system with the potential to turn into
a transformative energy technology62
One of such innovation hubs is the Joint Center for Artificial
Photosynthesis established in 2010 In the Netherlands a public private partnership was established to form
BioSolar Cells of which one of the main focal themes is AP Globally several hundreds of millions of euros
are being spent this decade on AP research and this research seems to be intensified further
Despite the intensification of global research efforts the communication cooperation and collaboration at
an international level remains limited Many AP consortia link different research groups but operate only at
a national level63
Yet a higher level of institutionalised international or global cooperation going beyond
international academic conferences could spur innovative research in the field and enhance knowledge
exchange and spill-overs A number of survey respondents indicated that the lack of coordination
communication and cooperation at an international level is one of the main weaknesses in current AP-related
research activities
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research
including research on artificial photosynthesis In Japan the industry is involved in AP research to a greater
degree64
Nevertheless although companies are participating in local consortia such as ARPChem and
BioSolar Cells there seems to be a lack of cooperation between academia and industry at an
international level
The transfer of research to industrial application in artificial photosynthesis remains challenging In order
to attract the attention of the private sector artificial photosynthetic systems must be cost-effective efficient
and durable An active involvement of industrial parties could help bringing research prototypes to
commercialisation This step towards commercialisation requires a sufficient critical mass and funding
however which cannot be borne by a single country
442 Strengths and weaknesses of AP research in Europe
Table 49 below summarises the strengths and weaknesses of research in artificial photosynthesis in Europe
as compared to non-European research
62
httpscienceenergygovbesresearchdoe-energy-innovation-hubs 63
The only exception is AMPEA with its pan-European reach 64
The Korean Centre for Artificial Photosynthesis (KCAP) collaborates with a number of companies Toshiba and Panasonic made some advances in artificial photosynthesis research (httpasianikkeicomTech-ScienceScienceHow-artificial-photosynthesis-could-cut-emissions) ARPChem has a few corporate members on board (httpwwwmetigojpenglishpress2012pdf1128_02bpdf)
75
Table 49 Summary of strengths and weaknesses of research in Europe
Strengths Weaknesses
A strong diverse community of researchers
RampD institutions research capacity and facilities
Existing research programmes and roadmaps for AP in
several MS
Available financial investments in MS
Ongoing and conducted FP7 projects at EU level
Close collaboration of research groups in consortia
Limited communication cooperation and collaboration at
a pan-European level
Limited collaboration between academia and industry
within Europe
Limited funding mostly provided for short-term projects
focusing on short-run returns
National RampD efforts in AP are scattered
Europe has a diverse research community working on artificial photosynthesis research covering all the
technology pathways Europersquos universities have many highly educated researchers in the fields of chemistry
physics and biology at their disposal There is a solid foundation of RampD institutions research capacity
and facilities such as specialised laboratories which work together at a national level
National research programmes and roadmaps for AP exist in several Member States an indication that
AP research is on the agenda of European governments65
Therefore also financial investment for AP
research is available in several MS such as in Germany66
and other countries European-level
collaboration between different research groups and institutes from different countries has been achieved in
the framework of FP7 projects67
as well as predecessors of it
Five main consortia in Europe ensure that research groups and research institutes are collaborating
closely68
such as in Sweden where the Consortium for Artificial Photosynthesis (CAP) is active and in the
Netherlands where researchers work in close cooperation within the BioSolar Cells consortium Nevertheless
there is still much room to expand globally as well as within Europe most consortia are operating within and
collaborating with research groups in countries where they are based themselves
The level of cooperation and collaboration at a pan-European level hence seems to be limited There
are a few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7 projects
but many research groups are operating locally and are funded by national governments Several survey
respondents reported a low degree of collaboration among different research groups which typically results in
a duplication of efforts and a lack of generalised standards Synergies which could potentially boost research
in artificial photosynthesis are being overlooked Creating for example a communication platform to facilitate
the exchange among researchers could more easily promote the development of knowledge and increase the
speed of discovery and exploitation of new robust (effective and durable) photocatalysts innovative processes
and devices etc Moreover another indicated weakness is the lack of collaboration between already existing
and ongoing projects
While industrial companies are present in a few consortia there is limited collaboration between European
academia and industry Improved collaboration could result in the development of more advanced AP
processes and AP process devices and it might improve the probability of APrsquos successful commercialisation
in the foreseeable future
65
For example Strategic Energy Technology (SET) Plan European Biofuels Technology Platform (EBTP) and European Industrial Bioenergy Initiative (EIBI) JCAP scientific programme For more information please refer to Deliverable 1 Chapter 32
66 By now research funded by the government of Germany in the field of artificial photosynthesis amounts to euro 42 million (httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf)
67 See Deliverable 1
68 httpswwwleopoldinaorgenpolicy-adviceworking-groupsartificial-photosynthesis
76
The long-term focus of AP research is a hurdle for both gaining cooperation with industry and for obtaining
funding Compared to that of its non-European counterparts European funding focuses on the short
term69
While in the USA and Japan funding is dedicated for about 5-10 years European parties often get
funding for about 4 years at the most Although several MS also have dedicated RampD programmes focusing
on AP the amounts provided by non-European counterparts exceed those of the European70
Furthermore
these national programmes are fragmented ie lacking a common goal and perspective hence the funding
of research is also fragmented and scattered71
The European community of researchers could benefit
from an integrated programme which clearly indicates research goals and objectives In addition a common
funding scheme set up to support fundamental research in artificial photosynthesis and to promote
collaboration with industry could advance the research in artificial photosynthesis
A number of survey respondents indicated that there is currently little focus of EU-funded research on
technologies with low TRL within H2020 At the moment there is a strong emphasis on the projects and
technologies which already have a rather high TRL expecting returns in the near future while research in the
area of low TRL technologies requires some attention and funding Several respondents mentioned that there
exist still quite some barriers regarding the design of low-cost materials with low TRL and with higher stability
and activity (eg performance of devices when it comes to a discontinuous supply of energy)72
45 Main industrial actors active in AP field
451 Industrial context
The idea behind artificial photosynthesis is that solar fuels could solve worldwide energy problems by using
water and carbon dioxide and converting them into the fuels we need Artificial photosynthesis can convert
sunlight directly into chemical fuels which makes it possible to harvest and store energy However there are
still many obstacles to make this technology commercially viable Only if artificial photosynthesis can be
provided efficiently stably safely and cheaply will it be beneficial for the public This means inter alia that an
efficient light absorber and catalysts need to be created to convert sunlight into fuel Even though there are
rapid developments in the field of artificial photosynthesis there are many obstacles to overcome in order to
reach mass production Currently the positioning of the fields of artificial photosynthesis and solar fuels is at
around a 3 on the technology readiness level
452 Main industrial companies involved in AP
At the moment the number of companies active in the field of AP is limited Based on our analysis of the main
AP actors in the industry only several tens of companies appear to be active in this field Moreover industrial
activity is limited to research and prototyping as viable AP technologies have not (yet) been commercialised
35 companies active in the field of AP have been identified comprising 16 European companies and 19 non-
European companies (Table 410) Seven of these are in Germany eight in the Netherlands eight in Japan
and 10 in the US The following table summarises the countries in relation to one or more of the technology
pathways
69
Already in 2013 it was indicated that much of public funding of basic AP research remains short term For more information see Thomas FaunceStenbjorn Styring Michael R Wasielewski Gary W Brudvig A William Rutherford et al (2013) Artificial Photosynthesis as a Frontier Technology for Energy Sustainability Energy amp Environmental Science Issue 4 2013
70 A number of respondents indicated that the available funding is not sufficient to finance research facilities and equipment
71 This weakness is indicated by several respondents
72 This is also mentioned as one of the areas of attention in Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press)
77
Table 410 Overview of the size of the industrial community number of companies per pathway
Country Synthetic biology amp
hybrid systems
Photoelectrocatalysis Co- electrolysis Total number of
companies
European companies
France 1 1 0 1
Germany 2 2 0 4
Italy 0 1 0 1
Netherlands 3 4 1 8
Switzerland 0 1 0 1
Total 6 9 1 15
Non-European companies
Japan 0 8 0 8
Saudi Arabia 0 1 0 1
Singapore 0 0 1 1
US 3 2 4 8
Total 3 11 5 19
Note a company can be active in multiple technology pathways
Source Ecorys
With respect to the industry largely the same countries stand out as in the research field namely Japan the
US and north-western Europe The industry in Japan appears to have the most intensive research activities
in AP as several large Japanese multinationals have set up their own AP RampD laboratoriesresearch
departments
With respect to the three technology pathways (i) synthetic biology amp hybrid systems (ii) photoelectrocatalysis
and (iii) co-electrolysis we have observed that most industrial (research) activity is being performed
concerning photoelectrocatalysis (19 companies) although there are also companies active in the two other
pathways
We have also identified a number of companies active in the area of carbon capture and utilisation that might
potentially be involved in the research of artificial photosynthesis
453 Companies active in synthetic biology amp hybrid systems
The pathway involving synthetic biology amp hybrid systems is still at an early stage on the TRL scale (TRL 1-2)
The challenges industries face relate mostly to efficiency obstacles Enzymes and proteins need to be
modified by genetic engineering Another barrier relates to the fact that the modifications and protein
production are still very time-consuming in terms of cell growthprotein purification Furthermore it is
necessary to improve protein stability and solubility by rational design directed evolution and modifying
sample conditions since currently proteins are unstable It would probably take about 10-20 years until
technologies reach TRL 7
The companies involved in this pathway range from chemical and oil-refining companies companies working
on bacteria companies producing organic innovative catalysts to others The following table lists the
organisations identified within this pathway
78
Table 411 Organisations in synthetic biology amp hybrid systems
Country Organisation (in EN)
France PhotoFuel
Germany Evonik Industries AG
Germany Brain AG
Italy Hysytech
Netherlands Biomethanol Chemie Nederland BV
Netherlands Photanol BV
Netherlands Tendris Solutions
Netherlands Everest Coatings
US Joule Unlimited
US Phytonix
US Algenol
Source Ecorys
Chemical and oil-refining companies
Biomethanol Chemie Nederland BV a Dutch company that produces and sells industrial quantities of high
quality bio-methanol focusing on synthetic biology amp hybrid systems is also a partner of the BioSolar Cells
programme The BioSolar Cells programme focuses its research on artificial photosynthesis photosynthesis in
cellular systems and photosynthesis in plants
Companies working on bacteria
Another group of companies in the pathway of synthetic biology amp hybrid systems focus on CO2 to fuel
processes that use cyanobacteria to convert CO2 into targeted fuels or chemicals (biological conversion)
Examples of such companies are Joule Unlimited Phytonix and Algenol all based in the US Algenol is
commercialising its patented algae technology platform for the production of ethanol using proprietary algae
sunlight carbon dioxide and saltwater The Dutch company Photanol uses cyanobacteria to turn CO2 into
certain predetermined products
Companies producing organic innovative catalysts
Many of the smaller companies currently active in developing AP originate from a specific research group or
research institute and focus on specific AP process steps andor process components Some companies
focus on the further development of both chemical and organic innovative catalysts which are earth-abundant
non-toxic and inexpensive Brain AG (Germany) is an example of such a company
Other companies
Hysytech is an Italian company experienced in technology development and process engineering applied to
the design and construction of plants and equipment for fuel chemical processing energy generation and
photoelectrocatalysis Hysytech is involved in an FP7 project to develop a fully artificial photoelectrochemical
device for low temperature hydrogen production
Other companies in the field of synthetic biology amp hybrid systems are Tendris Solutions (Netherlands) and
Everest Coatings (Netherlands) involved in the EET-Kiem project which focused on increasing the
absorption of visible light in the TiO2 photocatalyst by incorporating other elements in the structure and to
construct a photoelectrochemical reactor Photofuel in France and Phytonic in the US focus on synthetic
biology amp hybrid systems and photoelectrocatalysis Evonik Industries AG invests in synthetic biology amp
hybrid systems as well as carbon capture technologies which convert waste CO2 into products and fuels
79
454 Companies active in photoelectrocatalysis
The pathway of photoelectrocatalysis is relatively low on the TRL scale as well (TRL 1-4)
Photoelectrocatalysis would make it possible to use photovoltaic cells that absorb photons to facilitate water
splitting Research on photoelectrocatalysis using photoelectrochemical cells in particular is still at a very early
stage
Technologies pertaining to the photoelectrocatalysis pathway are not yet commercially viable with the main
challenges relating to the design of devices that are efficient stable and durable Further potential obstacles to
be taken into account relate to the incorporation of these technologies with other technologies that can
generate fuel molecules other than hydrogen
Most companies are involved in this pathway ranging from automotive manufacturers and electronic
companies to chemical and oil-refining companies The following table lists the organisations identified within
this pathway
Table 412 Organisations in the field of photoelectrocatalysis
Country Organisation (in EN)
France PhotoFuel
Germany Bauhaus Luftfahrt eV (Bauhaus Luftfahrt Research)
Germany ETOGAS
Italy Hysytech
Japan Toyota (Toyota Central RampD Labs)
Japan Honda (Honda Research Institute - Fundamental Technology Research Center)
Japan Mitsui Chemicals
Japan Mitsubishi (Mitsubishi chemicals Setoyama Laboratory)
Japan Sumitomo Chemicals (Energy amp Functional Materials Research Laboratory)
Japan INPEX Corporation
Japan Toshiba (Corporate Research and Development Center)
Japan Panasonic (Corporate Research and Development Center)
Netherlands InCatT BV
Netherlands Shell (Shell Game Changer Programme)
Netherlands Hydron
Netherlands LioniX BV
Saudi Arabia Saudi Basic Industries Corporation
Switzerland SOLARONIX SA
US HyperSolar
Source Ecorys
Companies in the automotive sector
Several automotive manufacturers are active in the field of AP mostly relating to the field of
photoelectrocatalysis In 2012 Honda opened a hydrogen station in Saitama Japan that converts sunlight
into hydrogen that could be used to power fuel-cell electric vehicles The station is focusing on
photoelectrocatalysis and turning sunlight into hydrogen via a high-pressure water electrolysis system that
was developed by Honda itself Since then there seems to be little activity from Honda73
73
httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
80
Figure 44 Hondarsquos sunlight-to-hydrogen station
Source httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
Toyota succeeded (in 2011) to generate organic compounds via artificial photosynthesis without using any
external energy andor material sources The system is focused on producing formic acid (which could be
used as a raw material in industry) In February 2016 Toyota Central RampD Labs announced that they
achieved the worldrsquos highest energy conversion efficiency rate of 46 with artificial photosynthesis using
water and carbon dioxide as raw materials and sunlight as energy to produce useful materials Toyota is also
researching new chemical reactions to generate more valuable organic compounds as a final product such as
methanol Toyota is primarily focused on photoelectrocatalysis The companyrsquos 2020 goal is to complete basic
testing for the creation of primary CO2-absorbing materials (material or fuel)74
Electronic companies
In addition to car manufacturers also electronic companies are involved in photoelectrocatalysis In December
2014 Toshiba announced its focus on producing a catalyst made of gold The company indicated that they
found a way to modify gold at the atomic level using nanotechnology which allows carbon dioxide to change
into other compounds at a lower voltage (with a record of 15 energy efficiency rate)75
In September 2015 Toshiba made public that the company developed a prototype of a new highly efficient
molecular catalyst (consisting of an imidazolium salt) that converts carbon dioxide into ethylene glycol without
producing other and unwanted by-products Most artificial photosynthesis technologies use a two-electron
reduction conversion process producing carbon monoxide and formic acid Others can achieve direct multi-
electron reduction but tend to produce many by-products and their separation can be problematic Toshibas
new molecular catalyst converts carbon dioxide into ethylene glycol via multi-electron reduction The long-term
goal of Toshibarsquos research work is to develop a technology compatible with carbon dioxide capture systems
installed at facilities such as thermal power stations and factories utilising carbon dioxide to provide (storable)
energy To this end Toshiba focuses on photoelectrocatalysis and further improvement of the conversion
efficiency by increasing catalytic activity and aims at practical implementation in the 2020s76
Panasonics artificial photosynthesis system is also focused on photoelectrocatalysis in particular on highly
efficient CO2 conversion which can utilise direct sunlight or focused light In 2012 Panasonic found that a
nitride semiconductor has the capability to excite the electrons with enough high energy for the CO2 reduction
reaction to take place Nitride semiconductors have attracted attention for their potential applications in highly
74
httpwwwtytlabscom and httpswwwasiabiomassjpenglishtopics1603_01html 75
httpwwwjapantimescojpnews20150412nationalscience-healthlab-photosynthesis-begins-to-bloomVw1YZP5f3IV 76
httpswwwtoshibacojprdcrddetail_ee1509_01html
81
efficient optical and power devices for energy saving However its potential was revealed to extend beyond
solid devices more specifically it can be used as a photoelectrode for CO2 reduction By making a devised
structure through the thin film process for semiconductors the performance as a photoelectrode has greatly
improved77
In September 2014 Panasonic Corporation managed to achieve a conversion efficiency rate of
0378
and not long after that the company announced to having achieved the first formic acid generation
efficiency of approximately 10 as of November 201479
According to Panasonic the key to achieving an
efficient artificial photosynthetic system lies in improved photoelectrodes and oxidation-reduction electrodes
Chemical and oil-refining companies
The developments with respect to solar fuels are also being supported by several chemical and oil-refining
companies Artificial photosynthesis has been an academic field for many years However in the beginning of
2009 Mitsubishi Chemical Holdings reported to be undergoing its own artificial photosynthesis research by
using sunlight water and carbon dioxide to create the carbon building blocks from which resins plastics and
fibres can be synthesisedrdquo80
In 2014 Mitsubishi established the research organisation Setoyama Laboratory
The Laboratory focuses on the development of artificial photosynthesis for chemical processes which is the
synthesis of raw materials such as ethylene propylene butenes etc by means of solar hydrogen obtained by
catalytic water splitting under visible light and CO2 emitted at a plant site81
The laboratory is also participating
in the ldquoArtificial Photosynthetic Chemical Processrdquo project (denoted ldquoARPChemrdquo) granted by NEDO (New
Energy Development Organization) In this project the following three programmes are conducted through
collaboration with academia and industry
1 Design of a photo semiconductor catalyst for water splitting
2 A membrane separation system for H2 from gas mixtures composed of H2 and O2 and
3 A catalytic process for the synthesis of lower olefins from H2 and CO2
The Japanese chemical companies Sumitomo chemicals and Mitsui Chemicals focusing on carbon
capture and photoelectrocatalysis are also participating in the ARPChem programme Sumitomo has its
own Energy amp Functional Materials Research Laboratory and is conducting research and development in a
broad range of fields Mitsui created the Mitsui Chemicals Catalysis Science Award and the Mitsui Chemicals
Catalysis Science Award of Encouragement in order to award recognition to national and international
researchers that have made substantial contributions to the field of catalysis science In 2014 it was the fifth
time that Mitsui has given these awards
Royal Dutch Shell cooperated with Bauhaus Luftfahrt in the EU-funded Solar-Jet project (2011-2015) in the
area of photoelectrocatalysis aimed at demonstrating an innovative process technology using concentrated
sunlight to convert carbon dioxide and water into synthesis gas (syngas) The syngas a mixture of hydrogen
and carbon monoxide is ultimately converted into kerosene by means of the commercial Fischer-Tropsch
technology With the first ever production of synthesised ldquosolarrdquo jet fuel the SOLAR-JET project has
successfully demonstrated the entire production chain for renewable kerosene obtained directly from sunlight
water and carbon dioxide (CO2)82
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University (US)
SOFI leads a global consortium that brings together universities from Rutgers University in New Jersey to
Uppsala University in Sweden83
SOFI focuses on both the water-splitting process (production of hydrogen)
and the CO2 reduction process (the reduction of carbon dioxide to carbon monoxide which in combination
77
httpnewspanasoniccomglobalpressdata201207en120730-5en120730-5html 78
httpswwwasiabiomassjpenglishtopics1603_01html 79
httpwwwpanasoniccomglobalcorporatetechnology-designtechnologyphotosynthesishtml 80
httpwwwdigitalworldtokyocomindexphpdigital_tokyoarticlesmanmade_photosynthesis_looking_to_change_the_world 81
httpwwwmcrccojpenglishrdsetoyama_laboratoryhtml 82
httpwwwsolar-jetaeropagepostsartsunlight-to-jet-fuel-european-collaboration-solar-jet-for-the-first-time-demonstrates-the-entire-production-path-of-ldquosolarrdquo-kerosene-4php
83 httpappsnorthbynorthwesterncommagazine2015springsofi
82
with hydrogen can be processed into eg methanol or synthetic gasoline) Total is also a partner of the
BioSolar Cells programme
INPEX Corporation is a Japanese oil company established in February 1966 as North Sumatra Offshore
Petroleum Exploration Co In addition to Mitsubishi Chemicals Sumitomo Chemicals and Mitsui Chemicals
INPEX also participates in the ldquoJapan Technological Research Association of Artificial Photosynthetic
Chemical Processrdquo (ARPChem) programme and engages in RampD projects with the aim to produce chemical
products like plastics and hydrocarbon fuel from photochemical catalysis INPEX Corporation is focused on
photoelectrocatalysis
Other companies
Other companies include Etogas (Germany) which develops builds and selects Power-to-Gas plants and
products related to Power-to-Hydrogen Power-to-SNG and Hydrogen-to-SNG LnCatT BV (Netherlands)
Hydron (Netherlands) Saudi Basic Industries Corporation (Saudi Arabia) and Hyper Solar () all focus on
photoelectrocatalysis LioniX BV (Netherlands - photoelectrocatalysis) and Solaronix SA (Switzerland -
photoelectrocatalysis) are focused on the further development of photoelectrochemical cells Hysytech and
Photofuel are in addition to the first pathway also involved in the second
455 Companies active in co-electrolysis
Even though co-electrolysis is the pathway at the highest levels of technical readiness compared to the other
two pathways not many companies are involved in it There are three electrolyser types capable of producing
hydrogen gas eg alkaline electrolysis polymer electrolyte membrane electrolysis and solid oxide electrolysis
cells (SOECs) Multiple designs are commercialised although SOECs using Fischer-Tropsch synthesis are
not yet commercially viable The companies involved in this pathway are mainly from the US Industries
combine co-electrolysis and the field of carbon capture Fuel cell products are used in the automotive
telecom defenceaerospace and consumer product sectors
The following table summarises the organisations in the field of co-electrolysis
Table 413 Companies in co-electrolysis
Country Organisation (in EN)
Netherlands Shell (Shell Game Changer Programme)
Singapore Horizon Fuel Cell Technologies
US Catalytic Innovations
US Opus 12
US LanzaTech
US Proton onsite
Source Ecorys
Companies include Proton onsite (US ndash PEM electrolysis) which manufactures hydrogen nitrogen and zero
air generators in a safe reliable and cost-effective way Horizon Fuel Cell Technologies (Singapore)
focuses on commercially viable fuel cells starting by simple products which need smaller amounts of
hydrogen The technology platform of horizon fuel cell technology is focused on three main topics PEM fuel
cell systems hydrogen supply and hydrogen storage Catalytic Innovations (US) Opus 12 (US) Lanzatech
(US) and Shell (NL) are also involved in the second pathway
83
456 Companies active in carbon capture and utilisation
The technology in the carbon capture and storage pathway can capture up to 90 of the CO2 and allows for
the separation of carbon dioxide from gases produced in electricity generation and industrial processes by
means of combustion capture and oxyfuel combustion The most advanced technologies are at TRL 7 eg
carbon capture in a coal plant
The following table shows the organisations active in the field of carbon capture and utilisationre-use
Table 414 Organisations active in carbon capture and utilisation
Country Organisation (in EN)
Denmark Haldor Topsoe
Germany Evonik Industries AG
Germany Siemens (Siemens Corporate Technology CT)
Germany Sunfire GmbH
Germany Audi
Switzerland Climeworks
UK Econic (Econic Technologies)
Canada Carbon Engineering
Canada Quantiam
Canada Mantra Energy
Iceland Carbon Recycling International
Israel NewCO2Fuels
Japan Mitsui Chemicals
US Liquid light
US Catalytic Innovations
US Opus 12
US LanzaTech
US Global Thermostat
Source Ecorys
Twelve companies currently only focus on carbon capture and utilisation These companies are therefore
technically not considered to be companies involved in artificial photosynthesis However they can potentially
be involved in AP research in the future Such companies include automotive manufacturers as well as
electronics companies Five companies are involved in carbon capture and one of the pathways
Automotive manufacturers
Audi is working together with the American company Joule Unlimited in order to research and produce lsquoe-
ethanolrsquo Joule optimised a production process in which microorganisms are able to produce and excrete
either ethanol or alkanes from carbon dioxide (CO2) and sunlight Audi and Joule opened a joint
demonstration plant in September 2012 where e-ethanol is produced in transparent plastic tubes (see Figure
45)
84
Figure 45 Demonstration facility of Audi and Joule in Hobbs (New Mexico)
Source httpwwwbest-practicesfrost-multimedia-wirecomjoule2015
In January 2014 Audi e-ethanol underwent its first-ever test cycle in the pressure chamber and glass engine
showing that fewer pollutants are produced in the combustion of e-ethanol than is the case with bio-ethanol84
Since 2011 Audi has also been collaborating with Joule to produce e-diesel Finally in November 2014 Audi
opened a research facility in Dresden with project partners Climeworks and the start-up Sunfire in order to
produce its first batches of synthetic diesel combining two innovative technologies CO2 capture from the
ambient air (Climeworks) and the power-to-liquid process for the production of synthetic fuel (Sunfire)85
Currently Audi is investing in carbon capture and utilisation technologies
Electronics companies
Electronics companies such as Siemens are also investing in carbon capture technologies Developers at
Siemens Corporate Technology (CT) in Munich are currently active in the project CO2-to-value The challenge
of the project is to charge only carbon dioxide with electrons and not the surrounding water molecules
because the latter would merely result in the production of conventional hydrogen Specialists at the University
of Lausanne in Switzerland and materials scientists at the University of Bayreuth are working with Siemens to
develop catalysts on their behalf Siemens takes on a pragmatic approach by focusing on only one step in the
AP process They are not yet trying to capture light Instead they are centring their research activities on
activating CO2 and converting it into products such as (i) ethylene which the chemical industry needs for the
production of plastics (ii) methane the main component of natural gas and (iii) carbon monoxide which can
be used to produce fuels such as ethanol86
Other companies
Figure 46 illustrates the process of NewCO2Fuels (NCF) an Israeli company focused on carbon capture
This is a high-temperature-driven CO2- and water-dissociation process that produces syngas (a mixture of
CO and H2) from which various synthetic fuels and chemicals can be produced
In the short term NCF is focusing on the design and building of a first pilot plant as well as raising the
necessary funds for it
In the mid term NCF plans to offer its technology to the energy intensive industries such as the steel
gasification and glass industries to transform their CO2 waste streams into feedstock
In the long term NCFrsquos vision is to use solar energy to convert CO2 captured immediately from the
atmosphere into valuable products
84
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 85
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 86
httpwwwsiemenscominnovationenhomepictures-of-the-futureresearch-and-managementmaterials-science-and-processing-co2tovaluehtml
85
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels
Source httpwwwnewco2fuelscoilproduct8overview
Furthermore some companies focus on chemical or biological CO2-to-fuel production Examples of
companies that focus on direct (co-electrolysis) CO2 to fuels production are Carbon Recycling (Iceland) and
Econic (UK ndash carbon capture) The company Liquid Light (US ndash carbon capture) focuses on the
electrochemical conversion of CO2 to chemicals
Other companies involved in carbon capture are Global Thermostat (US) Quantiam (Canada) Carbon
Engineering (Canada) Evonik Industries AG (Germany) and Haldor Topsoe (Denmark) Besides co-
electrolysis Catalytic Innovations Opus 12 and Lanzatech are also involved in carbon capture Mitsui
Chemical is focusing on carbon capture as well as photoelectrocatalysis
457 Assessment of the capabilities of the industry to develop AP technologies
Although there is a lot of research activity going on in the field of AP both at the academic and industrial level
the technology is clearly not yet ready for commercialisation However concrete test facilities and prototypes
are being developed and solar fuels have already been produced at a laboratory scale The technology is not
yet sufficiently efficient in order to be able to compete with other technologies producing comparable
chemicals and fuels Finding catalysts which are on the one hand Earth-abundant non-toxic and inexpensive
and on the other hand sufficiently efficient seems to be the biggest challenge With respect to the
technological efficiency of the AP processes the main bottlenecks are light capture (whole spectrum) getting
a good photocurrent density and using these charge carriers efficiently87
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade In September 2014 Panasonic Corporation managed to achieve a conversion
efficiency rate of 03 becoming the first to exceed the rate of 02 for regular plants In November 2014
Toshiba reached 15 which was followed by 20 achieved by the Japan Technological Research
Association of Artificial Photosynthetic Chemical Process (ARPChem) in February 2015 In February 2016
Toyota Central RampD Labs Inc announced that they achieved the worldrsquos highest energy conversion
efficiency rate of 46 with artificial photosynthesis by developing a semiconductor substrates-using iridium
and ruthenium catalyst They succeeded in increasing the efficiency rate a hundred-fold (an efficiency rate of
004 had been in achieved by Toyota in 2011)88
Figure 47 summarizes these efficiency rate developments
Several companies (eg Toshiba) hint at achieving efficiency rates of 10 and the first practical applications
87
httpwwwosa-opnorghomearticlesvolume_24february_2013featuresartificial_photosynthesis_saving_solar_energy_for 88
httpswwwasiabiomassjpenglishtopics1603_01html
86
of AP in the 2020s ARPChem aims to achieve a 10 level of energy conversion efficiency in 2021 (the rate
at which the manufacturing of raw materials for chemicals becomes economically viable)89
Figure 47 Transition of energy conversion efficiency of artificial photosynthesis
Source httpswwwasiabiomassjpenglishtopics1603_01html
It can also be observed that the big industrial investors in AP technology (research) already built interesting
partnerships with research centres and new innovative start-upscompanies For example
Audi works together with the innovative company Joule Unlimited (US) on the development of biologically-
derived e-ethanol and e-diesel and also works together with start-up company Sunfire on the production
of synthetic diesel
Siemens works together with specialists at the University of Lausanne in Switzerland and at the University
of Bayreuth Germany on innovative catalysts
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University
(US) that works on the water-splitting and CO2 reduction process and
Mitsubishi is one of the five industrial partners in the Japanese ARPChem programme (2012-2021)
focusing on artificial photosynthesis research in which various Japanese universities will be involved
(including Waseda University and Tokyo University)
46 Summary of results and main observations
The aim of this report was to gain an understanding and a clear overview of the main European and global
actors active in the field of artificial photosynthesis This has been achieved by
Identifying the main European and global actors active in the field of AP
Providing an assessment of the current level of investments in AP technologies
Assessing the key strengths and weaknesses of the main actors and
Assessing the capabilities of the industry to develop and exploit the AP technologies
Fuelled by the globally perceived need to find a green non-polluting and emission neutral energy source for
the future there has been much development in the field of artificial photosynthesis and considerable progress
has been made In addition the emergence of multiple consortia and governmental programmes and
international conferences in the last 10-15 years suggest that there is a higher awareness of the potential of
89
httpwwwmitsubishichem-hdcojpenglishcsrdownloadpdf13_25pdf
87
AP and that further advances are necessary The analysis has shown that although there have been some
promising developments especially in collaboration with industry much remains to be done for AP
technologies and processes to become commercially viable Milestones which will spur the development and
commercialisation process of AP encompass increased global and industry cooperation and the deployment
of targeted large-scale innovation projects following the example of the US innovation hubs
A summary of the results of the analysis and the main observations concerning the research and industry
actors active in the field of artificial photosynthesis is presented below It should be noted that the academic
and industrial community presented in this report is not exhaustive and especially with increasing interest in
AP more actors are expected to become active in the field
Research community
In general we observe that AP research has been intensified during the last decade given the increasing
number of emerging networks and communities We identified more than 150 research groups on AP
worldwide out of which more than 60 are located in Europe Due to the interdisciplinary character of AP
research combines expertise from biology biochemistry biophysics and physical chemistry The development
of research networks and consortia facilitates collaboration between different research groups and enables
them to benefit from synergies We identified six consortia in Europe and five outside of Europe respectively
Almost all of them are based in a specific country attracting primarily research groups from that country Only
one consortium AMPEA launched by the European Energy Research Alliance is truly pan-European with a
range of members across the EU
Table 415 Summary of findings size of research community
Number of research groups
Total in Europe 113
Number of research groups per pathway
Synthetic biology amp hybrid systems 53
Photoelectrocatalysis 69
Co-electrolysis 25
Total outside Europe 77
Number of research groups per pathway
Synthetic biology amp hybrid systems 30
Photoelectrocatalysis 59
Co-electrolysis 14
Source Ecorys
With respect to the three technology pathways (synthetic biology amp hybrid systems photoelectrocatalysis and
co-electrolysis) we observed that almost 85 of the research activities worldwide are focused on the first two
pathways (about 34 on the first pathway and 50 on the second) whereas the third pathway attracts only
about 16 of the research communityrsquos attention Only the Dutch AP consortium BioSolar Cells specifically
focuses on co-electrolysis Other consortia like ARPChem in Japan collaborating with industry prefer to
research artificial photosynthesis via photoelectrochemical catalysis as this pathway is the most mature and
with the highest probability of successful commercialisation
The diversity of the scientists involved is the biggest strength of this global AP research community
Furthermore all of the existing technological pathways in AP are covered which avoids lock-ins into one
pathway and increases the probability of success for AP in general AP is on the research agenda of several
countries which is proven by the existence of dedicated programmes roadmaps and funds Globally several
hundreds of millions of euros are being spent this decade on AP research and these investments seem to be
intensifying further Major shortcomings encompass a lack of cooperation between research groups in
88
academia on the one hand and between academia and industry on the other A more technical challenge is
the transfer of scientific insights into practical applications and ultimately into commercially viable products
The AP sector in Europe exhibits some strengths in comparison to its non-European counterparts but also
some weaknesses Europersquos scientific institutions are strong and its researchers highly educated
Furthermore RampD institutions and research facilities are available providing a solid ground for research
Some individual MS have their own research programmes roadmaps and funds Nevertheless the investment
does not reach the amount of funds available in some non-European countries and is rather short-term in
comparison to that of its non-European counterparts Furthermore both the national research plans and their
funding seem fragmented and scattered lacking an integrated approach with common research goals and
objectives At the European level however collaboration has been successful within several ongoing and
conducted FP7 projects Close collaboration between research groups could also be achieved through the
establishment of consortia Apart from the pan-European consortium AMPEA collaboration between research
groups of different countries is limited the consortia are primarily country-based and attract mostly research
groups from that respective country Lastly the level of collaboration between academia and industry seems
to be more limited in Europe compared to that within the US or Japan
Industrial actors
At this moment the number of companies active in the field of AP is limited AP is still mainly at the laboratory
level Most pathways are still at level 1 or 2 of technology readiness (TRL) implying that research is still being
conducted and used to improve feasibility Only co-electrolysis is at a more advanced stage and most
methods are already commercially viable
Based on our analysis of the main AP actors in the industry only several tens of companies appear to be
active in this field Moreover the industrial activity is limited to research and prototyping as viable AP
technologies are not (yet) in commercial operation The pathways synthetic biology amp hybrid systems and
photoelectrocatalysis are still at the lowest levels of technology readiness Research within the
photoelectrocatalysis pathway is still at an early stage as well however PV devices (semiconductor devices
similar to the ones used in PEC devices) have already been successfully commercialised Co-electrolysis on
the other hand is a technology already available for a longer time period in this pathway various
technologies to convert water and DC electricity into gaseous hydrogen and oxygen are already
commercialised In contrast the technologies producing hydrocarbons by Fischer-Tropsch synthesis
converting for example CO2 H2O and syngas into hydrocarbon fuels are still at an earlier stage of
development Co-electrolysis is therefore at a 1-9 TRL having both already commercialised technologies as
well as the Fischer-Tropsch synthesis
In total we have identified and analysed 33 industrial actors active in the field of AP 15 European and 18 non-
European industrial actors With respect to the industry largely the same countries stand out as in the
research field namely Japan the US and north-western Europe The industry in Japan appears to have the
most intensive research activities in AP as several large Japanese multinationals have set up their own AP
RampD laboratoriesresearch departments With respect to the three technology pathways we can observe that
most industrial (research) activity is being performed concerning photoelectrocatalysis
89
Table 416 Summary of findings size of industrial community
Number of companies
Total in Europe 15
Number of companies per pathway
Synthetic biology amp hybrid systems 6
Photoelectrocatalysis 9
Co-electrolysis 1
Total outside Europe 18
Number of companies per pathway
Synthetic biology amp hybrid systems 3
Photoelectrocatalysis 11
Co-electrolysis 5
Source Ecorys
The main hurdles in the synthetic biology amp hybrid systems pathway relate to the improvement of efficiency
and protein production speeds as well as stability and solubility by rational design With respect to the
technological efficiency of the AP processes relating to photoelectrocatalysis the main bottlenecks are light
capture (whole spectrum) obtaining a good photocurrent density and using these charge carriers efficiently
Co-electrolysis is mainly facing challenges to increase the lifetime of the devices to create concept on a
megawatt scale to search for substitution of noble metal catalysts and to develop technologies that are
capable of supplying the electricity required Furthermore some methods are still at a low TRL like the
Fischer-Tropsch synthesis Finding catalysts which are Earth-abundant non-toxic inexpensive and
sufficiently efficient remains a huge challenge To this end more public and private funding is needed
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade For example between 2011 and 2016 Toyota Central RampD labs made a significant
leap forward from an efficiency rate of 004 towards an efficiency rate of 46 Furthermore several
industrial actors (including Toshiba and ARPChem) have hinted at being able to achieve efficiency rates of
10 and the first practical applications of AP in the 2020s When academia are able to overcome the main
barriers with respect to AP the TRL will increase and the interest in AP from the industries will rise More
interest from the industries is necessary in order to push AP on the market and making it an economically
viable alternative renewable energy source
91
5 Factors limiting the development of AP technology
The overall concept followed in this study is to assess a number of selected ongoing research technological
development and demonstration (RTD)initiatives andor technology approaches implemented by European
research institutions universities and industrial stakeholders in the field of AP (including the development of
AP devices)
Seven AP RTD initiatives have been identified for the assessment of ldquolimiting factorsrdquo addressing the three
overarching technology pathways synthetic biology amp hybrid systems photoelectrocatalysis of water (water
splitting) and co-electrolysis (see Table 51)
The authors are confident that through the assessment of these selected European AP RTD initiatives a good
overview of existing and future factors limiting the development of artificial photosynthesis technology (in
Europe) can be presented However it has to be noted that additional AP RTD initiatives by European
research institutions universities and industrial stakeholders do exist and that this study does not aim to prove
a fully complete inventory of all ongoing initiatives and involved stakeholders
Table 51 Overview of the selected AP research technological development and demonstration (RTD) initiatives
AP Technology
Pathways AP RTD initiatives for MCA
Synthetic biology amp
hybrid systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Biocatalytic conversion of CO2
into formic acid ndash Bio-hybrid
systems
Photoelectrocatalysis
of water (light-driven
water splitting)
Direct water splitting with bandgap absorber materials and
catalysts
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
a) Direct water splitting with III-
V semiconductor ndash Silicon
tandem absorber structures
b) Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Co-electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
Electrolysis cells for CO2
valorisation ndash Industry
research
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges
Until today much progress has been made in the development of artificial photosynthetic systems
However a number of significant scientific and technological challenges remain to successfully scale-up
existing laboratory prototypes of different AP technology approaches towards a commercial scale
In order to ensure that AP technologies become an important part of the (long-term) future sustainable
European and global energy system and additionally provide high-value and low carbon chemicals for
industrial applications AP based production systems need to be
Efficient so that they utilise as much sunlight as possible to produce fuels andor chemicals The larger
the fraction of sunlight that can be converted to chemical energy the fewer materials and less land would
be needed for AP devices A target efficiency of about 10 (for AP based fuel production) is an initial goal
This is about ten times the efficiency of natural photosynthesis however it should be noted that AP
92
laboratory prototype devices with solar-to-hydrogen efficiencies of 5 and more have already been
developed
Durable so that AP systems can convert a lot of energy in their lifetime relative to the energy required for
the production and installation of the devices This is a significant challenge because some materials
degrade quickly when operated under the special conditions of illumination by discontinuous sunlight
Cost-effective meaning the raw materials needed for the production of the AP devices have to be
available at a large scale and the produced fuels andor chemicals have to be of commercial interest
Resource-efficient so that they minimise the use of rare and expensive raw materials (taking into
account trade-offs between material abundancy cost and efficiency)
Today significant improvements with respect to cost-efficiency lifetimedurability energy efficiency and
resource use are still required for all existing AP technology approaches
Table 52 provides an overview of the current and target performance for the assessed seven AP research
technological development and demonstration (RTD) initiatives within the three overarching technology
pathways of synthetic biology amp hybrid systems photoelectrocatalysis and co-electrolysis
93
Table 52 Overview of the current and target performance with respect to cost-efficiency lifetimedurability energy efficiency and resource use
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
Nitrogenase
activity wanes
within a few
days
Light energy
conversion
efficiency
gt10
(theoretical
limit ~15)
4 (PAR
utilization
efficiency) on
lab level (200 x
600 mm)
No data No data
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
CO2 reduction
energy
efficiency (full
system) gt10
(nat PS ~1)
NA (CO2
reduction
energy
efficiency for
full system) on
lab level
No data No data
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
gt500 hours
(stability goal)
gt40 hours
Solar-to-
hydrogen
(STH)
efficiency
gt17
STH efficiency
14
Reduction of
use of noble
metal Rh
catalyst and
use of Si-
based
substrate
material
1kg Rh for
1MW
electrochem
power output
Ge substrate
(for
concentrator
systems)
Si substrate
94
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Bandgap abs materials
Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency ~9
STH efficiency
49
Reduction of
use of rare Pt
catalyst
Pt used as
counter
electrode for
H2 production
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency
gt10
IPCE gt90
(efficiency
goal)
IPCE (incident
photon to
electron
conversion
efficiency) of
25
Reduction of
use of rare and
expensive raw
materials
High-cost Ru-
based photo-
sensitizers
used
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
SOFC capital
cost target
400 US$kW
Comp of
synthetic fuels
with fossil fuels
No data
gt20 years
(long term)
1000 hours
(stability goal)
~50 hours
(high SOEC
cell
performance
degradation
observed)
Power-to-
Liquid system
efficiencies
(full system
incl FT)
gt70
No data No data No data
Electrolysis cells for CO2
valorisation ndash Industry
research
Comp with
fossil chemi
and fuels (eg
CO ethylene
alcohols) 650-
1200 EURMt
No data
gt20 years
(long term)
10000 hours
(stability goal)
gt1000 hours
(laboratory
performance)
System
efficiencies
(full system)
gt60-70
95 of
electricity used
to produce CO
System
efficiencies
(full system)
40
No data No data
95
52 Current TRL and future prospects of investigated AP RTD initiatives
Table 53 presents an overview of the current TRL future prospects and an estimation of future required
investments for the assessed AP research technological development and demonstration (RTD) initiatives
It should be noted that due to the focus on specific selected AP RTD initiatives the investment requirements
listed below do not represent all of the RTD activities conducted by European research institutions
universities and industrial stakeholders within the three overarching technology pathways of synthetic biology
amp hybrid systems photoelectrocatalysis and co-electrolysis
Table 53 Overview of current TRL future prospects and estimated investment needs for investigated AP RTD initiatives
AP RTD Initiatives TRL achieved (June
2016)
Future Prospects Estimated Investment
needed
Photosynthetic microbial cell
factories based on cyanobacteria
TRL 3 (pres Init)
TRL 6-8 (for direct
photobiol ethanol prod
with cyanobacteria green
algae)
2020 TRL 4 (pres Init)
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Biocatalytic conversion of CO2 into
formic acid ndash Bio-hybrid systems TRL 3 2020 TRL 4
Direct water splitting with III-V
semiconductor ndash Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 (for III-VGe
tandem structures)
TRL 3 (for III-VSi tandem
structures)
2020 TRL 5 (for III-VGe
tandem structures)
2021 TRL 5 (for III-VSi
tandem structures)
Basic RTD 5-10 Mio euro
TRL 5 5-10 Mio euro
Direct water splitting with Bismuth
Vanadate (BiVO4) - Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 2020 TRL 5
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
TRL 3 2020 TRL 4
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
TRL 2-3 (for co-
electrolysis of H2O
(steam) and CO2)
2020 TRL 3-4 (for co-
electrolysis of H2O
(steam) and CO2)
Electrolysis cells for CO2
valorisation ndash Industry research
TRL 4 (for RE assisted
carbon compound
production)
TRL 3 (for full synthetic
photosynthesis systems)
2020 TRL 6 (for RE
assisted carbon
compound production)
2020 TRL 5 (for full
synthetic photosynthesis
systems)
TRL 6 10-20 Mio euro
53 Knowledge and technology gaps of investigated AP RTD initiatives
At present a number of significant scientific and technological challenges remain to be addressed before
successfully being able to scale-up existing laboratory prototypes of different AP technology approaches
towards the commercial scale
Table 54 presents an overview of the identified knowledge and technology gaps focusing on the assessed
AP research technological development and demonstration (RTD) initiatives
96
Table 54 Overview of knowledge and technology gaps of investigated AP RTD initiatives
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Photosynthetic microbial cell
factories based on
cyanobacteria
Further metabolic and genetic engineering of the strains
Further engineered cyanobacterial cells with respect to increased light
harvesting capacity
Streamlined metabolism toward hydrogen production for needed electrons
proteins and energy instead of being used in competing pathways
More efficient catalysts with higher turnover rates
Simple and reliable production systems allowing higher photosynthetic
efficiencies and the use of optimal production conditions
Efficient mechanisms and systems to separate produced hydrogen from other
gases
Cheaper components of the overall system
Investigation of the effect of pH level on growth rate and hydrogen evolution
Production of other carbon-containing energy carriers such as ethanol
butanol and isoprene
Improvements of the photobioreactor design
Up-scaling of photobioreactor (from present active surface of 200 x 600 mm)
Improvement of operating stability (from present about gt100 hours)
Improvement of PAR utilisation efficiency from the present 4 to gt10
Cost reduction towards a hydrogen production price of 4 US$ per kg
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Further metabolic and genetic engineering of strains
Reduction of reactive oxygen species (ROS) which are detrimental to cell
growth
Development of biocompatible catalyst systems that are not toxic to bacteria
Development of ROS-resistant variants of bacteria
Development of hybrid systems compatible with the intermittent nature of the
solar energy source
Development of strains for CO2 reduction at low CO2 concentrations
Metabolic engineering of strains to facilitate the production of a large variety of
chemicals polymers and fuels
Enhance (product) inhibitor tolerance of strains
Further optimisation of operating conditions (eg T pH NADH concentration
ES ratio) for high CO2 conversion and increased formic acid yields
Integration of enzymes into the hydrogen evolving part of ldquobionic leafrdquo devices
Mitigation of bio-toxicity at systems level
Improvements of ldquobionic leafrdquo device design
Up-scaling of ldquobionic leafrdquo devices
Improvement of operating stability (from present about gt100 hours)
Improvement of CO2 reduction energy efficiency towards gt10
Cost reduction of the production of formic acids and other chemicals
polymers and fuels
97
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Increased understanding of surface chemistry at electrolyte-absorber
interfaces
Further improvement of functionalization to achieve higher stabilities without
the need for protective layers
Reduction of defects acting as recombination centres or points of attack for
(photo)corrosion
Reduction of pinhole formation leading to reduced mechanical stability of the
Rh catalyst
Reduction of the amount of rare and expensive catalysts by the use of core-
shell catalyst nanoparticles with a core of an earth-abundant material
Reduction of material needed as substrate by employment of lift-off
techniques or nanostructures
Deposition of highly efficient III-V tandem absorber structures on (widely
available and cheaper) Si substrates
Development of III-V nanowire configurations promising advantages with
respect to materials use optoelectronic properties and enhanced reactive
surface area
Reduction of charge carrier losses at interfaces
Reduction of catalyst and substrate material costs
Reduction of costs for III-V tandem absorbers
Development of concentrator configurations for the III-V based
photoelectrochemical devices
Improvement of device stability from present gt40 hours towards the long-term
stability goal of gt500 hours
Improvement of the STH production efficiencies from the present 14 to
gt17
Cost reduction towards a hydrogen production price of 4 US$ per kg
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Improvements of the light absorption and carrier-separation efficiency
(currently still at lt60) in BiVO4
Better utilization of the solar spectrum by BiVO4 especially for wavelengths
close to the band edge (eg by plasmonic- andor resonance-enhanced
optical absorption)
Further development of novel water-oxidation catalysts based on for example
cobalt- and iron oxyhydroxide-based materials
Further development of the distributed n+ndashn homojunction concept for
improving carrier separation in high-donor density photoelectrode material
Improvement of the stability and avoidance of mass transport and light
scattering problems in devices based on nanoporous materials and DSSC
(Dye Sensitised Solar Cells)
Further development of Pulsed Laser Deposition (PLD) for (multi-layered)
WO3 and BiVO4 photoanodes
Although the near-neutral pH of the electrolyte solution ensures that the BiVO4
is photochemically stable proton transport is markedly slower than in strongly
alkaline or acidic electrolytes
Design of new device architectures that efficiently manage proton transport
and avoid local pH changes in near-neutral solutions
For an optimal device configuration the evolved gasses need to be
transported away efficiently without the risk of mixing
The platinum counter electrode needs to be replaced by an earth-abundant
alternative such as NiMo(Zn) CoMo or NiFeMo alloys
Improvement of device stability from present several hours towards the long-
term stability goal of 1000 hours
Scaling up systems to square meter range
Improvement of the STH production efficiencies from the present 49 to ~9
Cost reduction towards a hydrogen production price of 4 US$ per kg
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Deep molecular-level understanding of the underlying interfacial charge
transfer dynamics at the SCdye catalyst interface
Novel sensitizer assemblies with long-lived charge-separated states to
Design and construction of functional DS-PECs with dye-sensitised
photoanodes and dye-sensitised photocathodes (tandem DS-PEC structures)
Design and construction of DS-PECs where undesired external bias is not
98
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
enhance quantum efficiencies
Sensitizerndashcatalyst supramolecular assembly approach appears as effective
strategy to facilitate faster intramolecular electron transfer for long-lived
charge-separated states
Optimise the co-adsorption for efficient light-harvesting and charge collection
Organometal halide perovskite compounds as novel class of light harvesters
(for absorber applications in DS-PEC)
Encapsulation of perovskite compounds to prevent the dissolution in aqueous
solutions
Semiconductor quantum dots (QDs) as suitable sensitizers for DS-PEC
Exploration of more efficient OERHER catalysts with low overpotentials
Use of a redox mediator analogous to the tyrosine-histidine pair in PSII to
accelerate dye regeneration and thus achieve an increased charge
separation lifetime
One-dimensional TiO2 nanostructures such as TiO2 nanotubes and nanorods
to improved the charge transport properties and thus charge collection
efficiencies
Exploration of alternative SC oxides with more negative CB energy levels to
match the proton reduction potential
Search for alternative more transparent p-type SCs with slower charge
recombination and high hole mobilities
Further studies on phenomena of photocurrent decay commonly observed in
DS-PECs under illumination with time largely due to the desorption andor
decomposition of the sensitizers andor the catalysts
needed
Design and construction of DS-PECs with enhanced quantum efficiency
(towards 90 IPEC)
Ensure dynamic balance between the two photoelectrodes in order to properly
match the photocurrents
Development of efficient photocathode structures
Ensure long-term durability of molecular components used in DS-PEC devices
Reduce photocurrent decay due to the desorption andor decomposition of the
sensitizers andor the catalysts
Ensure active photosensitizer and catalyst for at least millions of cycles in 20ndash
30 years
Ensure long operating lifetimes (such as achieved for DSC) for stable DS-PEC
devices that incorporate molecular components Future work on developing
robust photosensitizers and catalysts firm immobilization of sensitizercatalyst
assembly onto the surface of SC oxide as well as the integration of the robust
individual components as a whole needs to be addressed
Scaling up systems to square meter range
Improvement of the STH production efficiencies IPCE (incident photon to
electron conversion efficiency) need to be improved from ~25 to gt90
Cost reduction towards a hydrogen production price of 4 US$ per kg
99
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Basic understanding of reaction mechanisms in co-electrolysis of H2O (steam)
and CO2
Basic understanding of dynamics of adsorptiondesorption of gases on
electrodes and gas transfer during co-electrolysis
Basic understanding of material compositions microstructure and operational
conditions
Basic understanding of the relation between SOEC composition and
degradation mechanisms
Development of new improved materials for the electrolyte (eg Sr- and Mg-
doped lanthanum gallate (LSGM) and scandium-stabilized zirconia (Sc- SZ))
Development of new improved materials for the electrodes (eg Sr- and Fe-
doped lanthanumcobaltate (LSCF)Sr-doped lanthanum ferrite (LSF)Co-
and Nb-doped barium ferrite (BCFN) and Sr- and Fe-barium cobaltate
(BSCF) perovskites)
Avoidance of agglomeration of Ni-particles and micro-cracks in Ni-YSZ
hydrogen electrodes
Avoidance of mechanical damages (eg delamination of oxygen electrode) at
electrolyte-electrode interfaces
Reduction of carbon (C) formation during co-electrolysis
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Replacing metallic based electrodes by pure oxides
Studies of long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O (steam) and CO2
Improvement of stability performance (from present ~50 hours towards the
long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Improvement of the co-electrolysis syngas production efficiencies towards
values facilitating the production of competitive synthetic fuels via FT-
processes
Cost reduction towards competitiveness of synthetic fuels with fossil fuels
Electrolysis cells for CO2
valorisation ndash Industry
research
Further research on catalyst development
Investigation of catalyst surface structure (highly reactive surfaces)
Catalyst development for a variety of carbon-based chemicals and fuels
Research on electrolyte composition and performance (dissolved salts current
density)
Research on light-collecting semiconductor grains enveloped by catalysts
Research on materials for CO2 concentration
Careful control of catalyst manufacturing process
Precise control of reaction processes
Development of modules for building facades
Stable operation of lab-scale modules
Stable operation of demonstration facility
Improvement of production efficiencies for carbon-based chemicals and fuels
Cost reduction towards competitiveness of the produced carbon-based
chemicals and fuels
100
54 Coordination of European research
Although RTD cooperation exists between universities research institutions and industry from different
European countries the majority of the activities are performed and funded on a national level Thus at
present the level of cooperation and collaboration on a pan-European level seems to be limited
There are few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7
projects and many research groups that are operating locally and are funded by national governments A low
degree of collaboration among different research groups was reported which results in a duplication of efforts
and a lack of generalized standards Synergies which could potentially boost research in artificial
photosynthesis are being overlooked Creating for example a communication platform to facilitate exchange
among actors could more easily promote the development of knowledge and increase the speed of discovery
and exploitation of new robust (effective and durable) photocatalysts innovative processes and devices etc
Another indicated weakness is the lack of collaboration between the already existing and ongoing projects
The coordination of research at a European level is mainly performed by AMPEA The European Energy
Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials amp Processes for Energy
Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging Technologies Artificial
photosynthesis became the first energy research subfield to be organised within AMPEA The goal of this joint
programme which was launched at the end of 2011 is to set up a thorough and systematic programme of
directed research which by 2020 will have advanced the technology to a point where commercially viable
artificial photosynthetic devices will be under development in partnership with industry
Currently AMPEA does not involve biological AP approaches as its main mission focuses on advanced
materials Therefore opportunities for research cooperation in the field of synthetic biology seem limited in the
short term
Furthermore it was stated that the current effectiveness of AMPEA to coordinate research at a European level
is limited also due to budget constraints and limited direct funding provided to AMPEA
Specifically efforts within AMPEA are currently centred on developing a concise RTD roadmap for AP
technologies in Europe The future implementation of this roadmap will require support on both national and
European levels
Table 55 (below) presents a list of European research collaborations within the investigated AP research
technological development and demonstration (RTD) initiatives
101
Table 55 (European) research cooperation within the investigated AP RTD initiatives
AP RTD Initiatives (European) Research cooperation
Photosynthetic microbial
cell factories based on
cyanobacteria
Initiative implemented by Uppsala University Sweden (within CAP) in cooperation with
Norwegian Institute of Bioeconomy Research (NIBIO)
Existing cooperation between Uppsala University and German car manufacturer VW
Biocatalytic conversion of
CO2 into formic acid ndash
Bio-hybrid systems
Initiative implemented by Wageningen UR Food amp Biobased Research and Wageningen UR
Plant Research International The Netherlands (within BioSolar Cells)
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
III-V semiconductor ndash
Silicon tandem absorber
structures
Initiative implemented by TU Ilmenau the Institute for Solar Fuels at the Helmholtz-Zentrum
Berlin and the Fraunhofer Institute for Solar Energy Systems ISE and the California Institute
of Technology (Caltech)
Existing cooperation between TU Ilmenau and epitaxy technology providers Space Solar
Power GmbH and Aixtron SE
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
Bismuth Vanadate
(BiVO4) - Silicon tandem
absorber structures
Initiative implemented by the Institute for Solar Fuels at the Helmholtz-Zentrum Berlin and
two Departments at Delft University of Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Further RTD was done at Repsol Technology Center from Spain in cooperation with
Catalonia Institute for Energy Research (IREC)
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
Initiative implemented by KTH Royal Institute of Technology Sweden in cooperation with
Dalian University of Technology China (within CAP)
Further RTD at University of Amsterdam (within BioSolar Cells) University of Grenoble
University of Cambridge and EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Existing cooperation between OMV and University of Cambridge
Existing cooperation between Siemens and EPFL
Co-electrolysis of steam
and carbon dioxide in
Solid Oxide Electrolysis
Cells (SOEC)
RTD performed at Technical University of Denmark Imperial College London University of
Sheffield and in previous years by Catalonia Institute for Energy Research (IREC) in
cooperation with Repsol Technology Center from Spain
Electrolysis cells for CO2
valorisation ndash Industry
Research
Initiative implemented by Siemens Corporate Technology (CT) in cooperation with the
University of Lausanne and the University of Bayreuth Germany
55 Industry involvement and industry gaps
Due to the low TRL (TRL 2-4) of present AP technology pathways in the areas of synthetic biology amp hybrid
systems photoelectrocatalysis of water (water splitting) and co-electrolysis the direct involvement of industry
in research and development activities in Europe is currently limited
Furthermore detailed information on industry activities in the AP field is difficult to find also due to issues of
confidentiality According to Cefic (European Chemical Industry Council) AP is regarded as a potentially
promising future technology option by the Councilrsquos members however information on industry involvement is
largely kept confidential
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research including
research in artificial photosynthesis However while companies are participating in local consortia such as
BioSolar Cells there currently seems to be a lack of cooperation between academia and industry at an
international level
102
Industry involvement in the area of synthetic biology amp hybrid systems
There is ongoing cooperation between Uppsala University and the German car manufacturer Volkswagen
within the framework of the European project ldquoPhotoFuelrdquo The project is coordinated by VW and focuses on
the production of butanol using micro-organisms
The European industry end users Volvo and VW are involved in the field of the design and engineering of
photosynthetic microbial cell factories based on cyanobacteria however are not directly involved in the
development of micro-organisms themselves
Furthermore in the USA the company Algenol Biofuels Inc is active in the field and operating a pilot scale
production unit
Industrial partners potentially interested in the development of ldquobionic leavesrdquo include the industry partners of
the Dutch BioSolar Cells programme Currently the coupling of the developed enzymes to the hydrogen-
evolving part of the device (ie the development of a full ldquobionic leafrdquo) is subject to ongoing patent procedures
by researchers of Wageningen UR
Industry involvement in the area of photoelectrocatalysis of water (water splitting)
The processes used for the deposition and processing of the devices based on two-junction tandem absorber
structures namely the metal-organic vapour phase epitaxy (MOCVD) and the in-situ functionalisation of
surfaces are generally scalable to an industrial level Spray pyrolysis processes used for the deposition of
dense thin films of BiVO4 are well-established industrial technologies and thus generally scalable to an
industrial level
Industrial stakeholders potentially interested in the area of direct water splitting with tandem absorber
structures include industry partners active in the field of epitaxy technology (eg producers and technology
providers such as Azur Space Solar Power GmbH and Aixtron SE which have ongoing long-term cooperation
with TU Ilmenau) suppliers of industrial process and specialty gases (eg Linde Group) and chemical
industries involved in catalytic processes (eg BASF Evonik)
Further interested industrial stakeholders include industry partners of the network Hydrogen Europe
(httphydrogeneuropeeu) and the Fuel Cells and Hydrogen Joint Undertaking (FCH JU
httpwwwfcheuropaeu) Hydrogen Europe (formerly known as NEW-IG) is the leading industry association
representing almost 100 companies both large and SMEs working to make hydrogen energy an everyday
reality The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) is a unique public-private partnership
supporting RTD activities in fuel cell and hydrogen energy technologies in Europe
The industry player Repsol from Spain was involved (on a research and development level) in the
development of photoelectrochemical water splitting based on metal oxides (WO3 BiVO4) through its Repsol
Technology Center in Spain in cooperation with the Department of Advanced Materials for Energy Catalonia
Institute for Energy Research (IREC) and the Department of Electronics University of Barcelona (UB) The
focus is currently centred on Pulsed Laser Deposition (PLD) for (multi-layered) WO3 and BiVO4 photoanodes
No full devices for photoelectrochemical water splitting have however yet been reported within this initiative
In the area of dye-sensitised PEC potentially interested industrial partners include the major fuel companies
Shell and Total who are already members of SOFI (Solar Fuels Institute based at Northwestern University)
an international research and innovation organisation with several European members (including the core
member Uppsala University) The Austrian fuel company OMV funds research at the Reisner Lab at the
Department of Chemistry at the University of Cambridge which is involved in both dye and catalyst
development
103
Successful technology transfer has recently been reported by Innovation Exchange Amsterdam (IXA) the
technology transfer office of the University of Amsterdam to the French company PorphyChem Rights were
licensed for the commercialisation of novel molecules for hydrogen generation so-called metalloporphyrins
innovative molecular photosensitizers which enable sustainable sunlight-driven hydrogen production from
water In cooperation with IXA the researchers filed patent applications with the European Patent Office on 26
February 2015 H-C Chen A M Brouwer Photosensitizer Europatent application 2015 EP15156740
The industry player Siemens AG from Germany is funding a project implemented by the Laboratory of
Photonics and Interfaces the Institute of Chemical Sciences and Engineering the School of Basic Sciences
and the Ecole Polytechnique Federale de Lausanne (EPFL) for the development of efficient photosynthesis of
carbon monoxide from CO2 using perovskite photovoltaics
Industry involvement in the area of co-electrolysis
Until today the involvement of industry in the research and development of the co-electrolysis of water and
carbon dioxide in Solid Oxide Electrolysis Cells (SOECs) in Europe is limited
Activities (on a research and development level) were performed by the industry player Repsol from Spain
through its Repsol Technology Center in cooperation with the Department of Advanced Materials for Energy at
the Catalonia Institute for Energy Research (IREC) The focus of these efforts is the replacement of metallic-
based electrodes by pure oxides offering advantages for industrial applications of solid oxide electrolysers
Thereby the aim is to ensure suitable H2CO ratios of the produced syngas (ie close to two) fulfilling the
basic requirements for synthetic fuel production
At present the focus of industrial engagement (eg sunfire Audi) for the production of synthetic carbon-based
fuels via concepts using (co)electrolysis and FT-processes favours water electrolysis (for the production of H2)
and the separate addition of CO2 in the FT-process over co-electrolysis of water and carbon dioxide
In April 2015 the company sunfire GmbH announced that it succeeded in producing synthetic diesel from air
water and green electrical energy A demonstration rig for power-to-liquids was inaugurated in November
2014 Recently the plant reached its full operating capacity and now produces synthetic diesel fuel Audi the
German car manufacturer and project partner of sunfire exposed the synthetic diesel to laboratory tests with
the result that the fuel was approved A larger plant needs to be developed in order to proceed towards a
commercial application of this process
An industry-driven approach towards the valorisation of carbon dioxide for the production of carbon-based
chemicals and fuels is implemented by Siemens Corporate Technology (CT) in Munich Germany This work is
implemented within the framework of the Siemens corporate project ldquoCO2toValuerdquo where catalyst
development is performed in cooperation with researchers from the University of Lausanne in Switzerland and
materials scientists at the University of Bayreuth
A small-scale lab unit based on an electrolyser cell is currently in operation at Siemens CT and a large-scale
demonstration facility is planned to be operational in the coming years in order to pave the way towards the
industrial application of this synthetic photosynthesis process for the production of carbon-based chemicals
and fuels to be introduced into the market
104
56 Technology transfer opportunities
The transfer of research to industrial application in artificial photosynthesis remains challenging In order to
attract the attention of the private sector artificial photosynthetic systems have to be cost-effective efficient
and durable The active involvement of industrial parties could help bring research prototypes to
commercialisation This step towards commercialisation requires sufficient critical mass and funding however
which cannot be borne by a single country
In the framework of the assessment of the seven AP technology approaches in the areas of synthetic biology
amp hybrid systems photoelectrocatalysis of water (water splitting) and co-electrolysis a number of ongoing
collaborations between research organisations and the industry as well as future opportunities for technology
transfer have been identified
Technology transfer opportunities in the area of synthetic biology
There are ongoing patent procedures by researchers at Wageningen UR on the coupling of developed
enzymes to the hydrogen-evolving part of the device (ie the development of a full ldquobionic leafrdquo)
Technology transfer opportunities in the area of photoelectrocatalysis of water (water splitting)
There are several patents filed by the researchers of TU Ilmenau and a patent on full device for direct
water splitting with III-V semiconductor based tandem absorber structures is under development
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC) and University of Barcelona (UB)
Successful technology transfer has been achieved by the technology transfer office of the University of
Amsterdam to the French company PorphyChem rights were licensed for the commercialisation of
metalloporphyrins as novel molecules for hydrogen generation which enable sustainable sunlight-driven
hydrogen production from water patent applications have been filed with the European Patent Office
There are technology transfer opportunities between OMV and the University of Cambridge and between
Siemens and EPFL on perovskite PV
Technology transfer opportunities in the area of co-electrolysis
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC)
There are technology transfer opportunities between Siemens and the University of Lausanne as well as
the University of Bayreuth
Table 56 below provides and overview of industry involvement and technology transfer opportunities
105
Table 56 Overview of industry involvement and technology transfer opportunities
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Uppsala University Sweden (within
CAP) in cooperation with Norwegian
Institute of Bioeconomy Research
(NIBIO)
Existing cooperation between Uppsala University
and German car manufacturer VW
Interest by end users Volvo and VW
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Wageningen UR Food amp Biobased
Research and Wageningen UR
Plant Research International The
Netherlands (within BioSolar Cells)
Industry partners of BioSolar Cells
Ongoing patent procedures by researchers of
Wageningen UR on the coupling of the developed
enzymes to the hydrogen evolving part of the
device (ie the development of a full ldquobionic leafrdquo)
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
TU Ilmenau Institute for Solar Fuels
at the Helmholtz-Zentrum Berlin and
the Fraunhofer Institute for Solar
Energy Systems ISE and the
California Institue of Technology
(Caltech)
Existing cooperation between TU Ilmenau and
epitaxy technology providers Space Solar Power
GmbH and Aixtron SE
Interest by suppliers of industrial gases (eg
Linde Group) and chemical industries involved
in catalytic processes (eg BASF Evonik)
Industry partners of network Hydrogen Europe
and the Fuel Cells and Hydrogen Joint
Undertaking (FCH JU)
Several patents filed by researchers of TU
Ilmenau
Patent on full device for direct water splitting with
III-V thin film based tandem absorber structures
under development
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Institute for Solar Fuels at the
Helmholtz-Zentrum Berlin two
Departments at Delft University of
Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
Further RTD at Repsol Technology
Center from Spain in cooperation
with Catalonia Institute for Energy
Research (IREC) and University of
Barcelona (UB)
RTD by Repsol Technology Center focus is
currently placed on Pulsed Laser Deposition
(PLD) for (multi-layered) WO3 and BiVO4
photoanodes No full devices for
photoelectrochemical water splitting have
however yet been reported
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC) and University of Barcelona (UB)
Dye-sensitised
photoelectrochemical cells -
molecular photocatalysis
KTH Royal Institute of Technology
Sweden in cooperation with Dalian
University of Technology China
Existing cooperation between OMV and
University of Cambridge
Existing cooperation between Siemens and
Successful technology transfer by technology
transfer office of University of Amsterdam to the
French company PorphyChem Rights were
106
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
(within CAP)
Further RTD at University of
Amsterdam (within BioSolar Cells)
University of Grenoble University of
Cambridge and EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
EPFL
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Fuel companies Shell and Total
licensed for the commercialisation of novel
molecules for hydrogen generation so-called
metalloporphyrins innovative molecular
photosensitizers which enable sustainable
sunlight-driven hydrogen production from water
Patent applications filed with the European Patent
Office
Technology transfer opportunities between OMV
and University of Cambridge and between
Siemens and EPFL on perovskite PV
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Technical University of Denmark
Imperial College London University
of Sheffield and Catalonia Institute
for Energy Research (IREC) in
cooperation with Repsol Technology
Center from Spain
RTD by Repsol Technology Center focus is the
replacement of metallic based electrodes by
pure oxides offering advantages for industrial
applications of solid oxide electrolysers
Sunfire and Audi (steam electrolysis and FT-
synthesis)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC)
Electrolysis cells for CO2
valorisation ndash Industry
research
Siemens Corporate Technology (CT)
in cooperation with the University of
Lausanne and the University of
Bayreuth Germany
Industry driven approach towards the
valorisation of carbon dioxide for the production
of carbon-based chemicals and fuels by
Siemens CT
Technology transfer opportunities between
Siemens and University of Lausanne University of
Bayreuth
107
57 Regulatory conditions and societal acceptance
The current very low oil prices as well as the low carbon price (ie the fee that must be paid for the right to
emit CO2 into the atmosphere) are hindering the market uptake of the low carbon AP-based production of
chemicals polymers and fuels (carbon-based fuels as well as hydrogen) In addition until today carbon
benefits are only monetised in the energy sector and not for the production of eg low carbon chemicals
Furthermore direct market incentives for solar fuels may be an opportunity for the future development of AP
technologies In addition investments made towards the establishment of a European infrastructure for
hydrogen storage and handling may be beneficial for the future development of AP technologies
Advancements in artificial photosynthesis have the potential to radically transform how societies convert and
use energy However their successful development hinges not only on technical breakthroughs but also on
the acceptance and adoption by energy users
It is therefore important to learn from experiences with other energy technologies (eg PV wind energy
nuclear energy biofuels) and thoroughly involve all societal actors in a discussion on the potential benefits
and drawbacks of the emerging technology already during the very early stages of development
Specifically barriers to social acceptance and issues causing public concern need to be addressed in an open
dialogue and potential measures mitigating concerns need to be discussed and implemented (where
possible) It needs to be kept in mind that the majority of the public is largely unaware of AP technologies
The following main topics are subject to public concern with respect to present AP technology pathways in the
areas of synthetic biology amp hybrid systems photoelectrocatalysis of water (water splitting) and co-
electrolysis
The use of genetic engineering and Genetically Modified Organisms (GMO) mainly for synthetic biology
approaches
The use of toxic materials for the production of AP devices which concerns all pathways
The use of rare and expensive raw materials for catalysts and absorber materials also for all pathways
Land use requirements for large-scale deployment of AP technology and land use competition with other
renewable energy options such as PV solar thermal applications and bioenergybiofuels
High societal costs involved in the development of AP technologies (efficiency and competitiveness of AP
technologies)
The importance of societal dialogue within the future development of AP technologies is widely acknowledged
within several national initiatives in Europe Initiatives on public involvement are implemented within the Dutch
BioSolar Cells programme and by the German National Academy of Science and Engineering (acatech)
109
6 Development roadmap
61 Context
611 General situation and conditions for the development of AP
Current energy technologies are unlikely to be sufficient to attain EU ndash and other international ndash long term
targets for the share of renewable energy sources in overall energy supplies beyond 2020 There is therefore
a strategic interest in supporting efforts to develop new energy technologies (and improve existing ones) and
to raise their competitiveness ndash eg in terms of costs efficiency and resource use ndash vis-agrave-vis those that are
currently available Thus from an energy policy perspective the motivation for accelerating the industrial
implementation of AP technologies arises from their potential to expand the available portfolio of competitive
sustainable energy sources thereby contributing to the continuation of the transition away from fossil fuels At
the same time from the perspective of growth and job creation developing and demonstrating the viability and
readiness for industrial deployment of AP technologies can be viewed as part of a wider industrial policy to
develop an internationally competitive European renewable energy technology industry
Processes based on AP have been identified as having the potential to deliver sustainable alternatives to
conventional fuels AP-based lsquowater-splittingrsquo processes may be used for the production of hydrogen or in
combination with lsquocarbon reductionrsquo for the production of carbon-based fuels (lsquosolar fuelsrsquo) and other higher
order carbon-based compounds However although AP technologies show great potential and despite the
significant progress in research in the AP field made in recent years there is still a significant way to go before
AP technologies are ready for industrial implementation
AP covers several technology pathways that are being developed in parallel and which are all at a low overall
level of technology readiness The individual processes sub-systems and components within the different
pathways are however at varying levels of maturity Consequently it is difficult to foresee the eventual
production efficiency costs and material requirements that could characterise future AP-based systems when
implemented on an industrial scale Moreover while it is possible that some AP technologies may end up
competing with each other complementarities and synergies may arise from AP technology development
activities that are currently being conducted largely in isolation from each other
To date application of AP has only been undertaken in small scale in laboratory conditions and the feasibility
of commercial industrial-scale deployment of AP systems has yet to be demonstrated Assuming that this can
be achieved at cost levels that enable AP-based products to be competitive in the marketplace commercial
implementation may raise some more practical issues for example in relation to land-use water availability
and other possible environmental or social concerns that have not as yet been fully explored
To appreciate the possible future role of AP technologies also requires consideration of other developments
shaping the energy supply and technology landscape Although by definition AP is concerned with the direct
conversion of solar energy into fuel technologies for specific processes developed within the context of AP
may eventually be linked to other renewable energy technologies for example if they are combined with
electricity generated from photovoltaics (PV) or other renewable sources such as wind energy Similarly the
production of lsquosolar fuelsrsquo using AP systems requires a source of carbon which may come in the form of CO2
from ambient air or alternatively by linking AP to carbon capture (and storage) systems90
90
See for example DG Research (2015) ldquoProceedings of the scoping workshop Transforming CO2 into value for a rejuvenated European economy Brussels 26th March 2015rdquo
110
Prospects for the future industrial implementation of AP technologies will not only depend on the lsquopushrsquo
provided by technological developments but will also depend on market lsquopullrsquo factors Not least the
commercial viability of fuels produced using AP technologies (and other renewable energy sources) will be
strongly influenced by price developments for other fuels particularly oil Current low oil and carbon
(emissions) prices must be taken into consideration as factors potentially hindering the market uptake of low
carbon AP-based production of chemicals polymers and fuels (including hydrogen) both now and in the
future
The overall market potential of solar fuels will also depend on public policy developments for example in
terms of regulatory frameworks and incentives affecting demand levels and costsprices of renewable energy
sources Similarly a concerted policy framework targeted towards promotion of a lsquohydrogen economyrsquo may
lead to a shift in emphasis for AP technology development towards hydrogen production (lsquowater splittingrsquo) ndash
already the more advanced area of AP research ndash and away from solar fuels Certainly until a higher
technology readiness level of AP is attained care should be taken to ensure that regulatory measures ndash
whether at European and national levels ndash do not impinge upon or hinder developments along the different AP
pathways
Finally in order to truly accelerate the industrial implementation of AP social acceptance and adoption of the
new technology by energy users must be acquired As it stands the majority of the public is largely unaware
of the development and significance of AP while those who are voice concerns about genetic engineering the
use of toxic materials the use of rare and expensive raw materials and the high societal costs involved in the
development along all technology pathways
612 Situation of the European AP research and technology base
Europersquos scientific communities form more than 60 of the 150 or so research groups on AP worldwide
boasting well-educated researchers and a diverse range of scientists - an interdisciplinary approach being
crucial for scientific advancement within this highly innovative field Together these groups cover all of the
identified existing technological pathways along which the advancement of AP might accelerate thus
increasing the likelihood of cooperation between European scientists with possible breakthroughs on any
given path
Significant improvements are still needed with respect to cost-efficiency lifetimedurability energy efficiency
and resource use for all existing AP technologies and progress is being made in addressing these knowledge
and technology gaps Yet while this technological development making strides along multiple pathways
simultaneously shows a considerable amount of potential the scientific community alone cannot accelerate
the development of the industrial implementation of AP Aiding the development from a currently low
technology readiness level and eventually commercialising AP will involve a host of enabling factors
including those of the financial structural regulatory and social nature
As it stands currently European investment into AP technologies falls short of the amounts being dedicated in
a number of non-European countries and it could be argued is rather short-term if not short-sighted Further
stifling the potential of these technologies is the fact ndash significant considering most European research activity
into AP operates at a national level (only one of the six consortia in Europe being pan-European) ndash that both
national research plans and their funding are fragmented lacking a necessary integrated approach Adding to
this fragmentation there appears to be a lack of cooperation between research groups and academia on the
one hand and between academia and industry on the other This suggests that there are some structural
barriers impeding the speed and success of the development and eventual commercialisation of AP in
Europe
111
Accelerating the development of AP requires bringing the best and brightest to the forefront of the research
being carried out in the field which would in turn involve a conscious effort to boost collaboration of the top
contributors across Europe - such an effort has been the cluster of several FP7 projects the good example of
which may well serve as a foundation on which to build in the future Once the divide between research
groups and academia has been breached and the technological advancement of AP technologies has been
given the push needed to be able to climb higher up the TRL scale interest from and in turn collaboration with
the industry should rise
62 Roadmap overview
The assessment of the existing lsquostate of the artrsquo undertaken for this study reveals that AP technologies are in
general currently at relatively low levels of technology readiness levels91
There are many outstanding gaps in
fundamental knowledge and technology that must be addressed before AP can attain the level of development
necessary for industrial scale implementation Moreover there is not as yet any compelling evidence to
suggest that any particular AP pathway or sub-approach therein can currently be identified as clearly lsquomore
promisingrsquo than another Given this situation it seems appropriate at least for the time being to adopt an
lsquoopenrsquo approach to possible support measures for AP-related research efforts which does not single out and
prioritise any specific AP pathway or sub-approach This conclusion corresponds to the broad consensus view
expressed by participants at the workshop on lsquoArtificial Photosynthesis in Horizon 2020rsquo held in May 2016
Notwithstanding the above assessment if AP is to establish a role in the overall portfolio of energy sources
then the longer-term objective must be to develop competitive and sustainable AP technologies that can be
implemented at an industrial scale Thus a technology development roadmap for AP must support the
transition from fundamental research and laboratory-based validation through to demonstration at a
commercial or near commercial scale and ultimately industrial replication within the market Upscaling of
technologies and integration of processes in a complete lsquovalue chainrsquo ie from light harvesting through to
solar fuel (and other AP-based products) will require greater levels of investment and inevitably will imply
making choices on which technology options to prioritise As the general aim (of the roadmap) is to accelerate
industrial implementation these choices should reflect market opportunities for commercial application of AP
technologies while bearing in mind the overarching policy objectives of increasing the share of renewable
energy sources in overall energy supplies
621 Knowledge and technology development
Following from the above in terms of knowledge and technology development activities the outline roadmap
for support for the development of AP technologies consists of three phases as illustrated in Figure 61 and
described in more detail in the following sub-sections
91
Although the situation of with respect to different process varies most are assessed to be only at TRL 3 or 4 (ie corresponding to lsquoexperimental proof of conceptrsquo or lsquotechnology validated in labrsquo)
112
Figure 61 General development roadmap visualisation
Phase 1 Phase 3Phase 2
Regional MS amp EU
Regional MS EU amp Private
Private amp EU
Private (companies)
FUNDINGSOURCE
TRL 9Industrial
Implementation
TRL 6-8Demonstrator
Projects
Pilot ProjectsTRL 3-6
TRL 1-3Fundamental
Research
RampDampI ACTIVITIES
2017 2025 2035
113
In the following description for convenience the timeline for activities is addressed in three distinct phases It
should be noted however that some AP technologies are more advanced than others and that they
accordingly could already be at or close to readiness for pilot projects (addressed under Phase 2)
Accordingly some laboratory-based validation (TRL 4) and lsquorelevant environmentrsquo validation projects (TRL 5)
may be envisaged within Phase 1 of the Roadmap Conversely as all fundamental knowledge and technology
issues will be not be solved within the 5-7 year time horizon foreseen for Phase 1 the need to support such
development through smaller scale research projects can be expected to continue into Phase 2 of the
Roadmap and possibly beyond
Furthermore in addition to support for fundamental knowledge and technology development the Roadmap
foresees the need to integrate lsquosupporting and accompanying activitiesrsquo (see Section 622) These activities
should run in parallel to the support for knowledge and technology development with initial activities starting
within Phase 1 of the Roadmap and continuing throughout the entire period of the Roadmap It may be
appropriate that some of the suggested activity areas are addressed as part of the proposed Networking
action (Action 2) and Coordinating action (Action 5)
Phase 1 - Time horizon short term (from now to year 5-7)
This phase will target the continuation of early stage research on AP technologies in parallel with initiation of
the process of scaling-up from laboratory based bench-scale projects towards pilot scale projects (ie to
validate whether bench scale projects are viable at a pilot scale) In keeping with the general status of AP
knowledge and technology development the scope of support during this phase should remain lsquoopenrsquo to all
existing (and potential) AP technology pathways and sub-options therein Such an approach should allow for
continued long-term advances in underpinning rsquogenericrsquo scientific knowledge that may lead to a breakthrough
in terms of newnovel approaches for AP while at the same time pushing forward towards addressing
technology challenges across the broad spectrum of AP pathwaysapproaches Notwithstanding this lsquoopenrsquo
approach eventual support may be directed towards specific topics that have been identified as areas where
additional effort is required to address existing knowledge and technology gaps
Under Phase 1 possible EU funding support should a priori be directed towards multiple small scale projects
(eg euro 3-5 million) that can complement existing regional and national programmes (and existing related EU-
level support)
Phase 1 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 1)
Recommendation Support for multiple small AP research projects
Objective To address outstanding gaps in fundamental knowledge and technology relating to AP
Rationale There are many remaining outstanding gaps in AP-relevant fundamental knowledge and
technology that must be addressed before AP systems can attain the level of development
necessary for industrial scale implementation This requires continued efforts dealing with
fundamental knowledge aspects of AP processes together with development of necessary
technology for the application of AP
Resources needed Project funding indicative cost circa euro 3-5 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact Strengthen diversify and accelerate knowledge and technology development for
processesdevices for AP-based production of hydrogen (water splitting) and carbon-based lsquosolar
fuelsrsquo
Priority
High
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
114
Recommendations to support knowledge and technology development (Action 2)
Recommendation Support for enhanced networking for AP research and technology development
Objective To improve information exchange cooperation and collaboration so as to increase efficiency and
accelerate AP-relevant knowledge and technology development towards industrial scale
implementation
Rationale AP research and technology development requires expertise across multiple and diverse
scientific areas both theoretical and applied Notwithstanding existing efforts to support and
enhance European AP research networks (eg AMPEA and precursors) AP research efforts in
the EU are fragmented being to a large extent organised and funded at national levels Further
development of EU-wide (and globally integrated) network(s) would promote coordination and
cooperation of research efforts within the AP field and in related fields addressing scientific
issues of common interest This action ndash offering secure funding for networking activities at a
pan-European level ndash should raise collaboration and increase synergies that potentially are being
currently overlooked
The broader international dimension of AP research and technology development could also be
addressed under this action In particular to develop instruments to facilitate research
partnerships beyond the EU (eg with US Japan Canada etc)
Resources needed Network funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact By providing a platform for knowledge exchange the speed of discovery and exploitation of
knowledge and technology developments should be accelerated both within the research
community and with industry
Priority
Medium
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
Recommendations to support knowledge and technology development (Action 3)
Recommendation AP Inducement Prize
Objective To provide additional stimulus for research technology development and innovation in the field
of AP while also raising awareness amongst the public and other stakeholders
Rationale The inducement prize would a priori target ldquoproof of conceptrdquo of AP at a bench-scale that meet
eligibility and award criteria set for the prize Experience suggests that lsquoinducement prizersquo
schemes can be particularly effective in situations corresponding to those of AP (ie where there
are a number of competing emergent technologies in the TRL 2-4 range that can potentially
deliver similar outcomes) The prize should provide an incentive for researchers to accelerate AP
RampD efforts and also potentially extend interest beyond the current AP research base to a wider
range of potential researchersinnovators
Resources needed Financial prize circa euro3 million
Prize organisation etc euro03 million
Actors involved Funding sources EU possible national (MS) contribution
Potential prize recipients Research and technology development institutions and (possibly)
industry
Expected impact Increased research intensity and wider participation resulting in turn to sooner than otherwise
demonstration of bench-scale AP devices This should provide for an earlier transition from
laboratory based research towards pilot projects
Priority
Medium
Suggested date of implementation92
Short (Phase 1)
92
Based on views gathered by the study there appears to be a general consensus that 3-4 years could be sufficient for the inducement prize contest timeframe Extending the timeframe for a longer period risks prize fatigue where contestants lose sight of the original prize aim and interest can start to wane
115
Phase 1 - Milestones
The scope of knowledge and technology development activities envisaged under Phase 1 is potentially very
broad as it covers multiple lsquopathwaysrsquo and a wide array of challengesissues ranging from general to highly
specific These concern each of the main AP steps (eg light harvesting charge separation water splitting
and fuel production) and range from materials issues device design and supporting activities such as process
modelling In general terms key criteria for evaluating overall progress towards the ultimate objective of
commercial implementation will revolve around factors such as efficiency of conversion of light into solar fuels
alongside the durability and potential cost-effectiveness of AP systems Shorter-term targets (lsquomilestonesrsquo)
could be set for minimum performance levels in terms of conversion efficiency (eg 10 conversion of solar
energy to hydrogen or to carbon-based fuels) although given the variation in progress across AP pathways
variable efficiency targets for individual pathways would seem appropriate
However if the purpose of the milestone is to mark the point of transition from Phase 1 to Phase 2 of the
Roadmap then a pragmatic milestone may be defined in terms of the development of an AP devicesystem
able to produce a lsquouseablersquo quantity of solar fuel in laboratory conditions sufficient to warrant further
development towards a pilot projectplant (Phase 2) In this regard it may make sense to a greater or lesser
degree to align the milestones for Phase 1 to the award criteria retained for the proposed inducement prize
Phase 2 - Time horizon medium term (from year 5-7 to year 10-12)
This phase will focus on reinforcing the implementation of pilot scale projects while initiating the process of
scaling up to a demonstration scale The scope of eventual support should focus on a limited number of
projects for the most promising AP technologies in order to demonstrate their viability at a pilot scale In this
context public (EU) funding support should be directed towards a limited number of medium scale projects At
the same time there should be encouragement of private sector participation in technology development
projects
Phase 2 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 4)
Recommendation Support for AP pilot projects
Objective To develop AP devices and integrated systems moving from laboratory scale up to an
(industrial) relevant scale of production This should enable comparative assessment of different
AP technology approaches at a production scale permitting industrial actors to make a
meaningful assessment of their potential viability for commercial deployment Equally these
projects should serve to identify (priority) areas where additional knowledge and technology
development is required in order to achieve industrial scale implementation
Rationale To reach industrial implementation of AP the feasibility of upscaling from laboratory conditions to
those approaching actual operational conditions needs to be demonstrated Accordingly pilot
projects under this Action item should provide for the testing and evaluation of AP devices to
assess and demonstrate the feasibility of reaching necessary characteristics (eg efficiency
levelstargets durabilitylife-cycle cost effectiveness) for commercial application for the
production of solar fuels The implementation of flexible pilot plants with open access to
researchers and companies should support (accelerated) development of manufacturing
capabilities for AP devices and scaling-up of AP production processes and product supply
Resources needed Project funding indicative cost circa euro 5-10 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Strengthen and accelerate knowledge and technology development for processesdevices for
AP-based production of hydrogen (water splitting) and carbon-based lsquosolar fuelsrsquo
Priority
High
Suggested date of implementation
Medium (Phase 2)
116
Recommendations to support knowledge and technology development (Action 5)
Recommendation Support for AP coordination
Objective To enhance efficiency (and effectiveness) of AP research efforts and more broadly to raise
coordination in the fields of solar fuels and energy technology development
Rationale There is a general need to ensure that research budgets are used effectively and to avoid
duplication of research effort In the context of AP there is a need to identify lsquomost promisingrsquo
technologies and set common priorities accordingly Moving to a common European AP
technology development strategy will require inter alia alignment of national research efforts in
the EU and (possible) cooperation at a broader international level Equally with the aim of
accelerating industrial implementation of AP there is a need to ensure cooperation and
coordination between research and technology development activities among the lsquoresearch
communityrsquo and industry
Resources needed Networkcoordination funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Improved coordination of AP research activities at European level (and possibly international
level) and improved priority setting to address knowledge and technology gaps for AP-based
processes and products
Priority
High
Suggested date of implementation
Medium (Phase 2) with possibility to extend implementation over
long term
Phase 2 - Milestones
The purpose of the AP pilot projects proposed under Phase 2 is inter alia to develop AP production
devicessystems operating at a sufficient scale to assess their potential viability for commercial deployment
Thus AP devicessystems developed within the pilot projects should attain sufficient performance levels and
fulfil basic operational and other characteristics (eg conversion efficiency lifetimedurability
sustainabilityresource use and cost-effectiveness) that are sufficient to attract the potential interest of private
sector (industry) investors Specific milestones for AP pilot projects may therefore be set in terms of multiple
target technical performance requirements but the overarching target lsquomilestonersquo for pilot projects will relate to
the overall assessment of their potential economic (commercial) viability conditional on further technological
developments (including engineering) and subject to their potential to comply with sustainability and other
social requirements
As a bottom line in terms of marking the point of transition from Phase 2 to Phase 3 of the Roadmap the test
for a lsquosuccessfulrsquo pilot project will be reflected in developing technology solutions able to attract private
investors willing to commit to their next stage of development either through a demonstration project (Phase
3) or directly to industrial implementation (lsquoearlyrsquo commercial projects)
Phase 3 - Time horizon long term (from year 10-12 to year 15-17)
This phase will focus of the development of ndash one or more ndash demonstration projects to assess the viability of
AP technologies at an industrial scale and facilitating the transfer of AP-based production systems from
demonstration stage into industrial production for lsquofirstrsquo markets The scope of eventual support should focus
on the AP technologies identified as most viable for commercialindustrial application However demonstration
level products should be led by the private sector ndash reflecting the need to assess commercial viability of
technologies ndash with co-funding provided by the public sector ndash reflecting the risk and large financial burden of
investments in such projects
117
Phase 3 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 6)
Recommendation Support for AP demonstrator projects
Objective To develop one or more demonstrator projects to assess the viability of AP technologies at a
close-to industrial scale (ie the project should be of a sufficient size to serve as a platform and
facilitating the transfer of AP-based production systems from demonstration stage into industrial
production for lsquofirstrsquo markets)
Rationale The demonstration project(s) provide a lsquostepping stonersquo between pilot projects and industrial
implementation The projects should not only provide validation of AP devices and systems but
also allow for developing and evaluating the integration of the full AP value chain93
By
demonstration the (commercial) viability of AP the project(s) should promote full industrial
investments that might otherwise be discouraged by the high cost and risk94
At the same time
beyond addressing technological and operational issues the demonstration projects should
address all other aspects ndash eg societalpolitical environmentalsustainability
economiccommercialfinancial legalregulatory geographic etc ndash necessary to evaluate how
AP based production of solar fuels could be implemented in practice
Resources needed To be determined
[Indicative budget envelope circa euro10-20 million per individual project However required funding
will depend on size and ambition of the project and may significantly exceed this amount]
Actors involved Funding sources Industry with EU support
Funding recipients Research and technology development institutions industry
Expected impact The projects should both build investor confidence in the commercial application of AP-based
solar fuel technologies and raise public confidence including in terms of safety and reliability
Priority
Medium
Suggested date of implementation
Long (Phase 3)
Phase 3 - Milestones
Given that the primary purpose of the demonstrator projects is to assess the viability of AP technologies at a
close-to industrial scale an initial milestone for such projects would be for the plants to be operational and to
be able to produce solar fuels in commercially significant volumes Ultimately the target lsquomilestonersquo will be to
produce solar fuels that are cost-competitive under actual market conditions and commercial requirements
while complying with other key requirements (eg safety societal acceptance etc)
622 Supporting and accompanying activities
The technological development of AP will throughout its various phases be guided by regulatory and market
measures as well as the degree of social acceptance In order to help secure favourable conditions for the
development and eventual commercialisation of AP technologies support will need to be provided from a very
early stage onwards within both of these spheres The prices of competing fuels and carbon emissions may
need to be regulated as well as incentives affecting the demand for renewable energy sources introduced
while the breadth of technological development regarding AP should not be hindered by regulation within the
current phase of research nor research into an eventual shift to a lsquohydrogen economyrsquo be put on the back
burner Thorough involvement of all societal actors in education and open debate regarding the potential
benefits and drawbacks of AP technologies as well as barriers to social acceptance and issues raising public
concern is also required At the same time the economic and commercial aspects of AP production
technologies and AP-produced solar fuels need to be understood including in terms of the development of
successful business models and the competitiveness of European industry in the field of AP and renewable
energy more generally
93
Where this covers the whole AP supplyvalue chain from upstream supply (eg materials components etc) to downstream demand (markets)
94 For example high cost resulting from accelerated investments to scale-up to industrial scale and high-risk profile resulting from uncertainty over which AP technologies may prove most successful together with uncertainty over operating costs and future market prices and demand for solar fuels etc These factors may otherwise discourage investments in (initial) full scale projects unless some public support is provided
118
There is potentially a wide range of themes ndash beyond purely technological and operational aspects ndash which
require to be better understood and which may be addressed through supporting and accompanying activities
including the following (non-exhaustive) topics
Industry engagement and technology transfer As far as can be ascertained the engagement of
industry in the field of AP technologies has to date been limited although because of its commercial
sensitivity it is difficult to obtain a clear picture of industrycompaniesrsquo interest in AP Nonetheless there is
a general view that a greater engagement of the industry would be beneficial for the development of AP
technologies and will become increasingly important as technologies reach higher TRLs and move closer
to commercial implementation An active involvement of industrial players in cooperative research projects
could facilitate the transfer of technology from the research community to industry (or vice versa) thereby
helping speed up the evolution from research prototypes and pilots to commercial implementation
Intellectual property protection To ensure future development and industrial application European
intellectual property in the area of AP should be adequately protected through patents At the same time
worldwide developments in AP-related patent-protected technologies should be taken into consideration
to ensure that Europe avoids potentially damaging dependences on non-European technologies
Regulatory conditions and support measures As a minimum AP technologies and products entering
the market should face a legal and regulatory environment that does not discriminate against their use and
provides a level playing field compared to other energyfuel types Beyond this there may be a public
policy justification (eg reflecting positive externalities of AP) for creating a specifically favourable
regulatory and legal framework to encourage the take-up and diffusion of AP technologies and products
At the same time other actions for example AP project financing support may be implemented to support
the industryrsquos AP investments these may be both for production investments but also for downstream
users faced by high switching costs (eg from fossil to solar fuels)
Societal aspects and safety AP technologies may potentially raise a number of public concerns that
need to be understood and addressed These may relate to safety aspects of the production storage
distribution and consumption of AP-based products for example there may be concern over the use of
genetically modified organisms (GMOs) in synthetichybrid AP processes Other areas of concern may
arise for example in relation to land use requirements or use of rare materials etc In general both
among the general public and even within the industry there is limited knowledge of AP Accordingly it
may be appropriatenecessary to implement activities to raise public and industry awareness of AP
Market potential relating to the assessment of the potential role and integration of AP energy supply and
demand Here multiple scenarios are possible for example depending on whether advances in AP
technology are targeted towards production of hydrocarbons or of hydrogen The former would require
fewer changes in terms of supporting infrastructure development (eg for fuel storage and distribution) but
is currently lagging behind in terms of AP technological development For the latter future market potential
will depend on the evolution towards a greater adoption of hydrogen-based fuel technologies Better
understanding of the shape and direction of market developments both within the EU and globally will be
important for assessing which AP technology developments offer the best prospects for future industrial
implementation At the same time the sensitivity of future prospects for AP technologies and products to
developments in the costs and market prices of competing (fossil and renewable) fuels should be
assessed
Industry organisation and business development relating to the assessment of future industrial
organisation of AP-technology production including the full supplyvalue chain for solar fuels (ie from
upstream supply of materials components equipment etc through fuel production to downstream market
supply including storage and distribution) Such an assessment will be required to better understand the
potential position and opportunities for the European industry in the area of AP which should also take
account of the business models and strategies for European players within the market
119
The aforementioned topics illustrate the diversity of the dimensions surrounding AP that require to be better
understood In a first instance more detailed economic legalregulatory social and other analyses of these
topics is warranted In turn this may lead to the formulation of more concrete policies and actions to develop
appropriate regulatory frameworks and to shape other market and business conditions in order to ensure a
supportive environment for the development and implementation of AP technologies and products
121
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(52) Grimme R A Lubner C E Bryant D A Golbeck J H Journal of the American Chemical Society
2008 130 6308
(53) Rumpel S Siebel J F Faregraves C Duan J Reijerse E Happe T Lubitz W Winkler M Energy amp
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(54) Volgusheva A Styring S Mamedov F Proceedings of the National Academy of Sciences 2013 110
7223
(55) Rozendal R A Jeremiasse A W Hamelers H V Buisman C J Environmental Science amp
Technology 2007 42 629
(56) Clauwaert P Toledo R Ha D v d Crab R Verstraete W Hu H Udert K Rabaey K Water
Science and Technology 2008 57 575
(57) Bajracharya S ter Heijne A Benetton X D Vanbroekhoven K Buisman C J Strik D P Pant
D Bioresource technology 2015 195 14
(58) Li M Canniffe D P Jackson P J Davison P A FitzGerald S Dickman M J Burgess J G
Hunter C N Huang W E The ISME journal 2012 6 875
(59) Zhang D Zhao Y He Y Wang Y Zhao Y Zheng Y Wei X Zhang L Li Y Jin T ACS
synthetic biology 2012 1 274
(60) Blankenship R E Tiede D M Barber J Brudvig G W Fleming G Ghirardi M Gunner M
Junge W Kramer D M Melis A science 2011 332 805
(61) Fujishima A Honda K Nature 1972 238 37
(62) James B D Baum G N Perez J Baum K N Square O V DOE report 2009
(63) Hanna M Nozik A Journal of Applied Physics 2006 100 074510
(64) Ross R T Hsiao T L Journal of Applied Physics 1977 48 4783
(65) Khaselev O Turner J A Science 1998 280 425
(66) Wang X Maeda K Chen X Takanabe K Domen K Hou Y Fu X Antonietti M Journal of the
American Chemical Society 2009 131 1680
(67) Kanan M W Nocera D G Science 2008 321 1072
(68) Brillet J Yum J-H Cornuz M Hisatomi T Solarska R Augustynski J Graetzel M Sivula K
Nature Photonics 2012 6 824
(69) Kim J H Kaneko H Minegishi T Kubota J Domen K Lee J S ChemSusChem 2016 9 61
(70) Gao L Cui Y Wang J Cavalli A Standing A Vu T T Verheijen M A Haverkort J E
Bakkers E P Notten P H Nano letters 2014 14 3715
(71) Standing A Assali S Gao L Verheijen M A van Dam D Cui Y Notten P H Haverkort J E
Bakkers E P Nature communications 2015 6
(72) Gao L Cui Y Vervuurt R H van Dam D van Veldhoven R P Hofmann J P Bol A A
Haverkort J E Notten P H Bakkers E P Advanced Functional Materials 2015
(73) Smolyakov G A Osinski M A Google Patents 2011
(74) Herrera A S Google Patents 2013
(75) Joo O S Jung K D Min B K Kim S H Oh J W Google Patents 2008
(76) Google Patents 2015
(77) Liu J Zhang Y Lu L Wu G Chen W Chemical Communications 2012 48 8826
(78) Li J Wu N Catalysis Science amp Technology 2015 5 1360
(79) Laguna-Bercero M A Journal of Power Sources 2012 203 4
123
(80) Graves C Ebbesen S D Mogensen M Solid State Ionics 2011 192 398
(81) Li W Wang H Shi Y Cai N International journal of hydrogen energy 2013 38 11104
(82) Fu Q Mabilat C Zahid M Brisse A Gautier L Energy amp Environmental Science 2010 3 1382
(83) Graves C Ebbesen S D Mogensen M Lackner K S Renewable and Sustainable Energy Reviews
2011 15 1
(84) Christopher K Dimitrios R Energy amp Environmental Science 2012 5 6640
(85) Sun X Chen M Jensen S H Ebbesen S D Graves C Mogensen M international journal of
hydrogen energy 2012 37 17101
(86) Ivy J Summary of electrolytic hydrogen production milestone completion report National Renewable
Energy Lab Golden CO (US) 2004
(87) Haering C Roosen A Schichl H Schnoumlller M Solid State Ionics 2005 176 261
(88) Mahmood A Bano S Yu J H Lee K-H Energy 2015 90 Part 1 344
(89) Jakobsson N B FRIIS P C BOslashGILD H J Google Patents 2014
(90) Stoots C M OBrien J E Herring J S Lessing P A Hawkes G L Hartvigsen J J Google
Patents 2011
(91) JABBAR M HOslashGH J Stamate E BONANOS N Google Patents 2013
[Ca
talo
gu
e n
um
be
r]
KI-N
A-2
7-9
87-E
N-N
KI-N
A-2
7-9
87-E
N-N
EUROPEAN COMMISSION
European Commission Directorate-General for Research amp Innovation
E-mail RTD-ENERGY-SR-APeceuropaeu
European Commission
B-1049 Brussels
EUROPEAN COMMISSION
Directorate-General for Directorate-General for Research amp Innovation
20164960
2016 EUR 27987 EN
Artificial Photosynthesis Potential and Reality
Final
Authors Olivier Chartier Paul Baker Barbara Pia Oberč Hanneke de Jong Anastasia Yagafarova (Ecorys) Peter Styring and Jordan Bye (Sheffield University) Rainer Janssen (WIP Renewable Energies) Achim Raschka and Michael Carus (nova Institut) Stavroula Evangelopoulou Georgios Zazias Apostolis Petropoulos Prof Pantelis Capros (E3MLab) Paul Zakkour (Carbon Counts)
November 2016
LEGAL NOTICE
The information and views set out in this report are those of the author(s) and do not necessarily reflect the
official opinion of the Commission The Commission does not guarantee the accuracy of the data included in
this study Neither the Commission nor any person acting on the Commissionrsquos behalf may be held
responsible for the use which may be made of the information contained therein
More information on the European Union is available on the Internet (httpwwweuropaeu)
Luxembourg Publications Office of the European Union 2016
Catalogue number KI-NA-27-987-EN-N
ISBN 978-92-79-59752-7
ISSN 1831-9424
Doi 102777410231
copy European Union 2016
Reproduction is authorised provided the source is acknowledged
Printed in the Belgium
Europe Direct is a service to help you find answers
to your questions about the European Union
Freephone number ()
00 800 6 7 8 9 10 11
() The information given is free as are most calls (though some operators phone boxes or hotels
may charge you)
5
Abstract
Technologies based on Artificial Photosynthesis (AP) offer the potential to deliver sustainable ldquosolarrdquo
alternatives to fossil fuels which are storable and transportable and can thus respond to the problem of
intermittency of other solar wind and marine energy technologies AP research has intensified over the last
decade pursuing multiple approaches or ldquopathwaysrdquo that each have their own relative advantages and
challenges However as most AP technologies are still at a low level of technology readiness it is currently
not possible to identify those AP pathways and specific technologies offering the greatest promise for future
industrial implementation The study argues accordingly that possible public support should retain an
approach that for the time being keeps Europersquos AP options open The proposed roadmap for support for AP
technology development which could be supported under Horizon 2020 foresees actions to address current
gaps in scientific knowledge and technology capabilities while scaling-up the size of projects through the
implementation of pilot projects and demonstrator projects that can validate the viability of AP technologies at
a commercial scale Europe occupies a frontline position in AP research with 60 of the estimated 150
leading global research groups located in Europe However AP research in Europe is relatively less well-
funded than elsewhere notably in the US and Japan European research efforts are also fragmented driven
by national-level strategies and research programmes Therefore the proposed roadmap integrates actions to
support improved networking and cooperation within Europe and possibly at a wider international-level In
turn improved coordination of national research efforts could be achieved through the elaboration of a
common European AP technology strategy aimed at positioning European industry as a leader in the AP
technology field
7
Executive Summary
Objectives and methodology
Artificial photosynthesis (AP) is considered among the most promising new technologies able to deliver
sustainable alternatives to current fuel supplies often viewed as a potential ldquogame changerrdquo in the fields of
energy conversion and energy production AP can be used to produce hydrogen or carbon-based fuels ndash
collectively referred to as ldquosolar fuelsrdquo ndash that offer an efficient and transportable store of (solar) energy which
can be used as an alternative to fossil fuels and as a feedstock for a wide range of industrial processes
Set against the above background the purpose of this study is to provide a full assessment of the situation of
AP providing answers to the questions Who are the main European and global actors in the field What is
the ldquostate of the artrdquo and what are the main ldquobottlenecksrdquo in scientific and technological development What
are the key economic and technological parameters to accelerate industrial implementation Answers to the
questions provide in turn the basis for formulating recommendations on the pathways to follow and the action
to take to maximise the eventual market penetration and exploitation of AP technologies
To gather information on the direction capacities and challenges of ongoing AP development activities the
study has conducted a comprehensive review of scientific and other literature and implemented a survey of
academics and industrial players This information together with the findings from a series of in-depth
interviews provides the basis for a multi-criteria analysis to identify key bottlenecks for the main AP
technology pathways The study findings were validated at a participatory workshop of leading European AP
researchers which also identified scenarios and sketched out roadmaps for actions to support the future
development of AP technologies over the short to long term
Definition of Artificial Photosynthesis
For the purposes of this study artificial photosynthesis is understood to be a process that aims to mimic
the physical chemistry of natural photosynthesis by absorbing solar energy in the form of photons and
using this energy to generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
Main technology pathways for artificial photosynthesis
It is difficult to precisely define the parameters of AP but there are three main identifiable technology pathways
along which research and development is now advancing
Synthetic biology amp hybrid systems aim to mimic existing biological systems that perform different stages of
photosynthesis (ie light-harvesting charge separation or molecule synthesis) and combine them to produce
specific fuel molecules These technologies are at a very early stage (TRL 1-4) however researchers have
already produced small quantities of hydrogen through the water-splitting reaction and have demonstrated the
reduction of carbon dioxide to methane and acetate Research is also investigating the possibility of using
basic cells (biological) to host biological machinery to generate more complex fuel molecules The long-term
goal is to reliably generate large quantities of fuel molecules combining and converting simple starting
compounds such as H2 and CO2 into a series of different compounds using enzymes and synthetic organic
and inorganic catalysts
8
Photoelectrocatalysis combines and integrates photovoltaic (PV) technologies ndash ie semiconductor materials
able to generate electric current from sunlight ndash with water electrolysis in a photoelectrochemical cell (PEC) or
suspensions of photoactive nanoparticles thereby enabling solar energy to be used to produce hydrogen (and
oxygen) via a water-splitting reaction PV technologies are already deployed commercially and are producing
power on a megawatt scale (TRL 7-8) however PECs to perform photoelectrocatalysis are as yet at a
relatively low stage of development (TRL 2-4) The main challenges facing this technology involve developing
materials that have high solar-to-hydrogen (STH) efficiencies are cheap to manufacture (eg use earth-
abundant metals) and are stable for long periods of time
Co-electrolysis uses co-electrolysis of carbon dioxide and water to generate syngas (COH2) by
simultaneously reducing carbon dioxide and water using a high temperature solid oxide cell electrolyser
(SOEC) syngas can then be used to generate simple intermediate compounds that can be used as feedstock
for more complicated chemicals Water electrolysers ndash such as alkaline and polymer electrolyte membrane
(PEM) electrolysers ndash used to convert water into H2 and O2 are mature technologies (TRL 7-8) that have
been commercialised SOECs are at a lower level of development (TRL 3-5) and given their high electricity
requirements current research is focused on increasing their efficiency
Technology pathways for artificial photosynthesis and indicative selection of generated compounds
Source University of Sheffield (PV = Photovoltaics)
AP research in Europe
Research in the AP field ndash bringing together interdisciplinary expertise from biology biochemistry biophysics
and physical chemistry ndash has intensified over the last decade Today more than 150 research groups are
estimated to be active worldwide of which 60 are in Europe1 Interest from industry is growing as well
although it remains limited due to the overall low levels of readiness for commercial application of many AP
technologies
Europe has a diverse community of researchers active in the AP field and covering all the main pathways with
the largest numbers of research groups located in Germany the Netherlands Sweden and the UK The most
significant and only truly pan-European-level research network is AMPEA2 but most networks and consortia
are national Some Member States have set up their own AP research programmes roadmaps and funds and
1 Source study estimates
2 Advance Materials and Processes for Energy Application (AMPEA) which is one of the joint programmes of the Europe nargy Research
alliance (EERA)
9
there has been successful collaboration in several ongoing European-funded FP7 projects Overall however
the level of funding in Europe falls short of that available elsewhere and national research plans (and funding)
seem fragmented and scattered with a short-term focus and lacking an integrated approach with common
research goals and objectives Equally the level of collaboration between academia and industry seems to be
more limited in Europe compared for example to the US or Japan
Relatively few companies are active in the field of AP and they can be counted in the lsquotensrsquo rather than
lsquohundredsrsquo Co-electrolysis is the only area where AP-related technologies are currently commercially viable
while current industry research activities mostly concern photoelectrocatalysis where companies from various
sectors (eg ranging from automotive and electronics to chemicals and oil refining) are involved There is
some industry involvement in synthetic biology amp hybrid systems but it is limited reflecting the early stage of
research activities along this pathway
Main challenges to development and implementation of AP technologies
To form a sustainable and cost-effective part of future European and global energy systems and a source of
high-value and low carbon feedstock chemicals the development of AP technologies must address certain
fundamental requirements
Efficiency in each main step of AP light captureharvesting (eg maximising the percentage of the
spectrum that can be utilised) energy transfer to a reaction centre (eg minimising energy loss during the
transfer) and charge generation and separation to allow the desired chemical reaction to take place (eg
preventing charge recombination)
Durability of the system in terms of the amount of energy that can be produced during the lifetime of an AP
system which is a challenge because of the rapid degradation of some materials under AP system
conditions (eg lack of long-term stability in aqueous conditions or when exposed to sunlight)
Sustainability of material use eg minimising the use of rare and expensive raw materials
To meet these requirements the main AP technology pathways must overcome several gaps in fundamental
knowledge and technology development (see tables) Even if these gaps can be addressed and the feasibility
of commercial- and industrial-scale deployment of AP systems can be demonstrated at a cost level that
enables AP-based products to be competitive in the market place commercial implementation may raise other
practical concerns These may arise in relation to land use water availability and possible environmental or
social concerns which have not yet been fully explored
Synthetic biology amp hybrid systems
Knowledge gaps Technology gaps
Develop molecular and synthetic biology tools to enable
the engineering of efficient metabolic processes within
microorganisms
Improve metabolic and genetic engineering of
microorganism strains
Improve metabolic engineering of strains to facilitate the
production of a large variety of chemicals polymers and
fuels
Enhance (product) inhibitor tolerance of strains
Minimise losses due to chemical side reactions (ie
competing pathways)
Develop efficient mechanisms and systems to separate
collect and purify products
Improve stability of proteins and enzymes and reduce
degradation
Develop biocompatible catalyst systems not toxic to
micro-organisms
Optimise operating conditions and improve operation
stability (from present about gt100 hours)
Mitigate bio-toxicity and enhance inhibitor tolerance at
systems level
Improve product separation at systems level
Improve photobioreactor designs and up-scaling of
photobioreactors
Integrate enzymes into the hydrogen evolving part of
ldquobionic leafrdquo devices
Improve ldquobionic leafrdquo device designs
Up-scale ldquobionic leafrdquo devices
Improve light energy conversion efficiency (to gt10)
Reduce costs of the production of formic acids and other
chemicals polymers and fuels
10
Photoelectrocatalysis
Knowledge gaps Technology gaps
Increase absorber efficiencies
Increase understanding of surface chemistry at
electrolyte-absorber interfaces incl charge transfer
dynamics at SCdyecatalyst interfaces
Develop novel sensitizer assemblies with long-lived
charge-separated states to enhance quantum
efficiencies
Improve charge transfer from solid to liquid
Increase stability of catalysts in aqueous solutions
develop self-repair catalysts
Develop catalysts with low over-potentials
Reduce required rare and expensive catalysts by core-
shell catalyst nanoparticles with a core of an earth-
abundant material
Develop novel water-oxidation catalysts eg based on
cobalt- and iron oxyhydroxide-based materials
Develop efficient tandem absorber structures on (widely
available and cheaper) Si substrates
Develop nanostructure configurations promising
advantages with respect to materials use optoelectronic
properties and enhanced reactive surface area
Reduce charge carrier losses at interfaces
Reduce catalyst and substrate material costs
Reduce costs for tandem absorbers using silicon-based
structures
Develop concentrator configurations for III-V based
tandem absorber structures
Scale up deposition techniques and device design and
engineering
Improve device stability towards long-term stability goal
of gt1000 hours
Improve the STH production efficiencies (to gt10 for
low-cost material devices)
Reduce costs towards a hydrogen production price of 4
US$ per kg
Co-electrolysis
Knowledge gaps Technology gaps
Basic understanding of reaction mechanisms in co-
electrolysis of H2O (steam) and CO2
Basic understanding of the dynamics of
adsorptiondesorption of gases on electrodes and gas
transfer during co-electrolysis
Basic understanding of material compositions
microstructure and operational conditions
Develop new improved materials for electrolytes and
electrodes
Avoid mechanical damages (eg delamination of
oxygen electrode) at electrolyte-electrode interface
Reduce carbon (C) formation during co-electrolysis
Optimise operation temperature initial fuel composition
and operational voltage to adjust H2CO ratio of the
syngas
Replace metallic based electrodes by pure oxides
Improve long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O
(steam) and CO2
Improved stability performance (from present ~50 hours
towards the long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel
composition and operational voltage to adjust H2CO
ratio of the syngas
Improvement of co-electrolysis syngas production
efficiencies towards values facilitating the production of
competitive synthetic fuels via FT-processes
Cost reduction towards competitiveness of synthetic
fuels with fossil fuels
The AP technology development roadmap
Although AP technologies show great potential and despite significant progress made in recent years there is
still a significant way to go before they are ready for industrial implementation Although some aspects of AP-
based systems are well developed the assessment of the existing lsquostate of the artrsquo shows that AP
technologies are generally at low levels of technology readiness (eg TRL 3-4) Moreover there is not yet
compelling evidence to suggest any AP pathway (or sub-approach therein) is ldquomore promisingrdquo than another
This being the case it seems appropriate to adopt an ldquoopenrdquo approach to possible support measures for AP-
related research efforts in the near term which does not single out and prioritise any specific AP pathway or
approach
Nonetheless if AP technologies are to fulfil their potential it will be necessary to achieve the transition from
fundamental research- and laboratory-based validation to demonstration at commercial of near-commercial
scales this ambition forms the long-term goal for the proposed AP technology development roadmap
11
The roadmap distinguishes 3 phases (see figure below) and corresponding recommendations for specific
actions
Phase 1 (short term) Early stage research and scaling-up to pilot projects
Action 1 Support for multiple small AP research projects to address existing knowledge and technology gaps and to
promote long-term advances in scientific knowledge that may contribute to breakthroughs in novel
approaches for AP and to address technology challenges across the board of current (and potential) AP
pathways and approaches
Action 2 Support for enhanced networking of AP research and technology development to reduce fragmentation and
promote coordination and cooperation of research efforts in the AP and related fields through the support for
pan-European networking activities and promotion of research synergies
Action 3 Inducement prize to provide additional stimulus for research technology development and innovation
through a (financial) prize targeting ldquoproof of conceptrdquo of significant advances in the AP field
Phase 2 (medium term) Pilot project implementation and scaling-up to demonstrator projects
Action 4 Support for AP pilot projects to demonstrate the viability of AP concepts through support for a (limited)
number of pilot plant scale projects of the ldquomost promisingrdquo AP technologies
Action 5 Support for AP coordination to ensure effective use of research budgets and to avoid duplication of research
efforts Moving to a common European AP technology strategy requires inter alia alignment of national
research efforts and cooperation at a broader international level Equally to accelerate industrial
implementation cooperation and coordination of activities among the lsquoresearch communityrsquo and industry
should be promoted
Phase 3 (long term) Demonstrator project implementation
Action 6 Support for AP demonstrator projects to demonstrate the viability of AP technologies through support for one
or more demonstrator projects that facilitate the transfer of AP production systems to industrial production for
ldquofirstrdquo markets while allowing an evaluation of the development and integration of the full AP value chain (ie
from upstream supply of materials and components to downstream markets for AP-based products) The
demonstrator project(s) should also address other aspects (eg societal political environmental economic
and regulatory) necessary to evaluate the practical implementation of AP technologies
NB For convenience the timeline of these actions is presented in 3 distinct phases Some AP technologies are however
more advanced than others and could already be at or close to readiness for pilot projects Conversely certain fundamental
knowledge and technology issues cannot expect to be resolved in the short term Accordingly the different phases as
proposed within the roadmap should not be considered to define a strictly chronological sequencetiming of actions
12
Visualisation of the AP technology development roadmap with illustrative project examples
Source Ecorys
Phase 1 Phase 3Phase 2
TRL 9 Industrial Implementation
TRL 6-8 Demonstrator
TRL 3-6 Pilot Projects
TRL 1-3 Fundamental
2017 2025 2035
Example projects- Research on metabolic and genetic engineering of strains for photosynthetic microbial cell factories
- Research on strains for the production of a variety of chemicals polymers and fuels
- Research on the understanding of surface chemistry at electrolyte-absorber interface in PEC
- Development of novel water-oxidation catalysts for direct water splitting
- Research on improvements of light absorption and carrier separation efficiency in PEC devices
- Research on new materials for electrodes and electrolytes in electrolysis cells
-Research to improve the basic understanding of reaction mechanisms in co-electrolysis (dynamics of adsorptiondesorption of gases gas transfer degradation mechanisms etc)
Example of projects - Improvements of operating stability of microbial cell factories
- Improvements of bionic leaf device design
- Study on long-term durability of molecular components used in DS-PEC devices development of active photosensitizer and catalyst
- Improvement of device stability and STH production efficiencies for direct water-splitting devices at pilot plant scale
- Support the development of lab-scale modules and demonstration facilities of electrolysis cells for CO2 valorisation
- Support the upscaling of cells for efficient co-electrolysis of H2O (steam) and CO2 in Solid Oxide Electrolysis Cells (SOEC)
- Development at a near-commercial scale of demonstrator plant(s) for co-electrolysis
Example of projects- Pilot plant scale of photobioreactors for photosynthetic microbial cell factories
- Pilot plant scale of ldquobionic leafrdquo devices
- Development at a near-commercial scale of demonstrator plant(s) for direct water-splitting devices based on several absorber materials (eg dye-sensitised photo-electrochemical cell (DS-PEC) device silicon-based tandem absorber structures)
13
Supporting activities
Looking beyond the technological and operational aspects of the roadmap the study finds several areas
where actions may be taken to provide a better understanding of the AP field and to accelerate development
and industrial implementation namely
Networking and coordination of research With the exception of the few pan-European initiatives (eg AMPEA
and FP7 projects) the degree of collaboration among research groups is low Networking and coordination
activities (for example through Horizon 2020 Coordination amp Support Action - CSA) would contribute to reduce
duplication of efforts and facilitate exchange among researchers
Industry engagement and technology transfer Engagement of industry in development activities which has so
far been relatively limited will become increasingly important as AP technologies move to higher levels of
readiness for commercial implementation Encouraging active involvement of industrial players in research
projects could ease the transfer of technology from the research community to industry (or vice versa) thereby
helping expedite the evolution from prototypes and pilots to marketable products
Public policy and regulatory conditions To encourage industrial implementation and market penetration AP
technologies and products should face a legal and regulatory environment that offers a ldquolevel playing fieldrdquo
compared to other energyfuel types Beyond this reflecting the sustainability and environmental
characteristics of AP there may be a public policy justification for creating a regulatory and legal framework
and possibly other measures to specifically encourage the adoption and diffusion of AP technologies and
products
Safety concerns and societal acceptance AP technologies could potentially raise a number of public
concerns for example the safety aspects of the production storage distribution and consumption of AP-
based products the use of GMOs in synthetichybrid AP processes the use of rare expensive andor toxic
materials extensive land use requirements etc Such legitimate public concerns need to be identified
understood and properly addressed if AP is to overcome barriers to widespread societal acceptance These
aspects should be an integral part of an overall AP research agenda that provides for open dialogue even
from very early stages of technological development and identifies potential solutions and mitigating
measures
Protection of Intellectual Property To become a successful leading player in the development and industrial
application of AP technologies researchers and industry must be able to adequately protect their intellectual
(industrial) property rights (eg patent protection) without this becoming a barrier to overall technology
development and implementation It will be important to both protect European intellectual property rights
while also follow global developments in AP-related patent-protected technologies thereby ensuring that
Europe has a secure strategic position in the AP field and avoiding potentially damaging dependencies on
non-European technologies
15
Table of contents
Abstract 5
Executive Summary 7
Table of contents 15
1 Introduction 21
2 Scope of the study 23
21 Overview of natural photosynthesis 23
22 Current energy usage and definition of artificial photosynthesis 25
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the study29
231 Synthetic biology amp hybrid systems 31
232 Photoelectrocatalysis of water (water splitting) 31
233 Co-electrolysis 31
3 Assessment of the technological development current status and future perspective 33
31 Synthetic biology amp hybrid systems 34
311 Description of the process 34
312 Current status review of the state of the art 35
313 Future development main challenges 38
32 Photoelectrocatalysis of water (water splitting) 39
321 Description of the process 39
322 Current status review of the state of the art 41
323 Patents 44
324 Future development main challenges 45
33 Co-electrolysis 47
331 Description of the process 47
332 Current status review of the state of the art 52
333 Patents 53
334 Future development main challenges 54
34 Summary 54
4 Mapping research actors 57
41 Main academic actors in Europe 57
411 Main research networkscommunities 57
412 Main research groups (with link to network if any) 59
42 Main academic actors outside Europe 62
421 Main research networkscommunities 62
422 Main research groups (with link to network if any) 64
43 Level of investment 66
431 Research investments in Europe 67
432 Research investments outside Europe 71
44 Strengths and weaknesses 73
441 Strengths and weaknesses of AP research in general 73
442 Strengths and weaknesses of AP research in Europe 74
16
45 Main industrial actors active in AP field 76
451 Industrial context 76
452 Main industrial companies involved in AP 76
453 Companies active in synthetic biology amp hybrid systems 77
454 Companies active in photoelectrocatalysis 79
455 Companies active in co-electrolysis 82
456 Companies active in carbon capture and utilisation 83
457 Assessment of the capabilities of the industry to develop AP technologies 85
46 Summary of results and main observations 86
5 Factors limiting the development of AP technology 91
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges 91
52 Current TRL and future prospects of investigated AP RTD initiatives 95
53 Knowledge and technology gaps of investigated AP RTD initiatives 95
54 Coordination of European research 100
55 Industry involvement and industry gaps 101
56 Technology transfer opportunities 104
57 Regulatory conditions and societal acceptance 107
6 Development roadmap 109
61 Context 109
611 General situation and conditions for the development of AP 109
612 Situation of the European AP research and technology base 110
62 Roadmap overview 111
621 Knowledge and technology development 111
622 Supporting and accompanying activities 117
7 References 121
17
List of figures
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton
gradient NADPH and ATP 24
Figure 22 Worldwide consumption of fuel types by percentage 27
Figure 31 General development and supply chain 33 Figure 32 Diagrammatic representation of a PSI-platinum hybrid system 34
Figure 34 Photoelectrochemical cell capable of water oxidation using solar energy 40
Figure 35 PEC reactor types 42
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting
photoelectrochemical cells 47 Figure 37 Schematic diagram of water electrolysis being conducted in an alkaline electrolyser 48
Figure 38 Schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell 49
Figure 41 Research groups in Artificial Photosynthesis in Europe 62
Figure 42 Research groups active in the field of AP globally 66
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020 69
Figure 44 Hondarsquos sunlight-to-hydrogen station 80
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels 85
Figure 61 General development roadmap visualisation 112
19
List of tables
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
36
Table 01 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the
performance data for each device This table was originally constructed by Ursua et al 201211
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis
cell electrolysers This table was originally constructed by Carmo et al 20138 53
Table 41 Number of research groups and research institutions in European countries 59
Table 42 Number of research groups per research area (technology pathway) 60
Table 43 Number of research groups and research institutions in non-European countries 64
Table 44 Number of research groups per research area (technology pathway) 65
Table 45 Investments in the field of artificial photosynthesis 66
Table 46 EU FP6 and FP7 projects on artificial photosynthesis 68
Table 47 Total EU budget on artificial photosynthesis per technology pathway 68
Table 48 Summary of strengths and weaknesses of research globally 73
Table 49 Summary of strengths and weaknesses of research in Europe 75
Table 410 Overview of the size of the industrial community number of companies per pathway 77
Table 411 Organisations in synthetic biology amp hybrid systems 78
Table 412 Organisations in the field of photoelectrocatalysis 79
Table 413 Companies in co-electrolysis 82
Table 414 Organisations active in carbon capture and utilisation 83
Table 415 Summary of findings size of research community 87
Table 416 Summary of findings size of industrial community 89
21
1 Introduction
To establish a world-class technology and innovation sector that is fit to cope with the challenges up to 2020
and beyond the European Commission initiated an update of its EU energy research and innovation (RampI)
policy leading to the publication of the Communication ldquoTowards an Integrated Strategic Energy Technology
(SET) Plan Accelerating the European Energy System Transformation (C (2015) 6317 final) in September
2015 Under the heading ldquoKeeping Technology Actions Openrdquo the SET Plan Integrated Roadmap states that
ldquothe emergence of new technologies required for the overall transition of the energy sector towards
decarbonisation requires breakthroughs which have to be based on fundamental and generic knowledge at
the international state of artrdquo Artificial Photosynthesis counts among the most promising new technologies and
is often considered as a potential ldquogame changerrdquo technology in the fields of energy conversion and energy
production
The study ldquoAssessment of artificial photosynthesisrdquo has been implemented in the first semester of 2016
against this background the study aims to support future policy developments in the area in particular in the
design of public interventions allowing to fully benefit from the potential offered by the technologies The study
has three specific objectives The first objective is to provide a detailed review of the state of the art of artificial
photosynthesis technologies as well as an inventory of research players from the public and private sector
The second objective is to analyse the factors and parameters influencing the future development of these
technologies The third objective is to provide recommendations for public support measures aimed at
maximising this potential
The structure of the report is as follows Section 2 describes the scope of the study with a review of the
different types of Artificial Photosynthesis Section 3 provides an assessment of the technological
development based on a review of the literature Section 4 maps the main academic and industrial actors
Section 5 analyses the factors limiting the development of Artificial Photosynthesis technologies and a
development roadmap is presented in the Section 6
23
2 Scope of the study
21 Overview of natural photosynthesis
Photosynthetic and heterotrophic organisms exist together in a steady state in the biosphere Photosynthetic
organisms capture solar energy in the form of photons this captured energy is used to produce chemical
energy that the organism uses to form adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide
phosphate (NADPH) ATP and NADPH are then used to generate organic compounds such as carbohydrates
from water and carbon dioxide12
Photosynthesis can be broken down into two processes light-dependant
reactions and carbon-assimilation reactions where the latter are driven by the products of the light reactions
In the light reactions electrons are obtained from water molecules that have been oxidised in a process often
referred to as ldquowater splittingrdquo to form electrons (e-) hydrogen ions (H
+) and molecular oxygen (O2) The
electrons are driven through a series of membrane-bound carrier proteins including cytochromes iron-sulphur
proteins and quinones to produce a proton gradient which is used to generate ATP and NADPH this is
summarised in Figure 21 The carbon-assimilation reactions use NADPH ATP electrons and H+ to reduce
carbon dioxide in a series of enzymatic reactions to generate an array of compounds21213
The light-dependent and carbon assimilation reactions of photosynthesis take place in the chloroplasts of
eukaryotic cells Chloroplasts are intracellular organelles with a non-uniform shape similar to that of
mitochondria They both have inner and outer membranes that enclose an inner compartment which is
permeable to small molecules and ions respectively The thylakoid membrane contains the photosynthetic
pigments and enzyme complexes that carry out the light reactions and ATP synthesis and are on the inside of
the inner membrane Chlorophylls are present in the thylakoid membrane and are responsible for absorbing
solar energy in plants An array of chlorophylls is called a photosystem Chlorophylls are green pigments
consisting of long phytol chains with a polycyclic planar structure similar to the protoporphyr in haemoglobin
at the top of the molecule However instead of a Fe2+
at the centre there is a Mg2+
coordinated by four
nitrogen atoms The phytol chain is esterified to a carboxyl group in ring IV The groups on the edge of the ring
(=CH2 and -CH3) can be exchanged for other groups depending on the organism the chlorophyll is present in
The heterocyclic five-ring system that surrounds Mg2+
has an extended polyene structure with alternating
single and double bonds These compounds strongly absorb in the visible region and have high extinction
coefficients Plants always contain chlorophyll α and chlorophyll β which both absorb green light at slightly
different wavelengths this maximises the amount of light the organism can utilise Chlorophylls bind with
specific proteins and membranes to form light-harvesting complexes (LHCs) In addition to chlorophylls which
are the main pigments in plants there are accessory pigments called carotenoids that absorb photons that
have different wavelengths so more of the spectrum can be utilised When a photon is absorbed by a
chlorophyll an electron in the chromophore portion is raised to a higher energy state called the excited state
When the electron moves back down to its ground state it can release the energy as light or heat In
photosynthesis instead of the energy being released as light or heat it is transferred from the excited
chromophore to a neighbouring chromophore in a process called ldquoexcitation transferrdquo1213
All of the pigment molecules in a photosystem can absorb photons and transfer the energy to other pigments
but only a number of pigments are associated with the photochemical reaction centre (PRC) The excitation
energy can be passed through multiple pigment molecules until it reaches a pigment associated with the PRC
The PRC transduces the excitation energy into chemical energy by passing the excitation energy to a nearby
molecule acting as an electron acceptor This leaves the chlorophyll with a positive charge which is
neutralised by another electron donor the electron acceptor becomes negatively charged In this way
excitation caused by photon absorption causes electric charge separation and starts the oxidation-reduction
chain Light-driven electron transfer in chloroplasts during photosynthesis is carried out by a number of multi-
enzyme complexes in the thylakoid membrane1213
24
Photosynthetic bacteria usually have one or two reaction centres Purple bacteria pass electrons through a
pheophytin which is a chlorophyll without the Mg2+
at the centre of the ring to a quinone Green sulphur
bacteria pass electrons through a quinone to an iron-sulphur centre The photosynthetic machinery in purple
bacteria is made up of 3 basic units a single reaction centre (P870) a cytochrome bc1 electron-transfer
complex (similar to complex III found in mitochondria) and an APT synthase Absorption of a photon drives
electrons through pheophytin and a quinone to the cytochrome bc1 complex following which electrons pass
through this complex to the cytochrome bc1 complex and back to the reaction centre This movement of
electrons generates the energy needed by the cytochrome bc1 complex to pump protons across the
membrane and create the gradient that generates ATP1213
The photosynthetic apparatus of cyanobacteria and plants is more complex than that found in a one-system
bacterium due to them containing two photosystems in the thylakoid membrane Photosystem II acts like the
single photosystem found in purple bacteria It should be noted that the water-splitting reaction occurs at
PSII14
When the reaction centre of photosystem II (P680) is excited electrons are driven through the
cytochrome b6f complex which pumps hydrogen ions across the thylakoid membrane to generate a proton
gradient PSI aids in the reduction of NADP+ to NADPH by absorbing a photon at 700 nm to excite an
electron which is passed through a number of carrier molecules to plastoquinone and then to ferredoxin-
NAPD+ reductase which generates NADPH As previously discussed the proton gradient that has been
generated from transferring the electrons that were excited by the photons is used by ATP synthase to
generate ATP To summarise the light-dependent reactions cause water to split into oxygen electrons and
protons which are used to generate a proton gradient form NAPDH from NAPD+ and generate ATP The
main differences between the two photosystems are the wavelengths of light they absorb and that PSII
conducts water oxidation (while PSI does not) Both absorb photons and both are capable of generating
ATP12-16
In the carbon-assimilation reactions ATP and NADPH are used to reduce (gain electrons) carbon
dioxide to form phosphates starch and sugars as part of the Calvin cycle which takes place in the stroma
this process is also known as carbon fixation1213
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton gradient NADPH and ATP
Theoretically the efficiency of natural photosynthetic systems should be around 26 This is calculated by
knowing the energy content of a glucose molecule is 672 kcal mol-1
To generate a glucose molecule 48
photons with a wavelength of 680 nm are needed which together have an energy of 42 kcal per quantum
mole which is equal to 172 kcal mol-1
672 kcal mol-1
divided by 172 kcal mol-1
makes for 26 efficiency
However in reality an efficiency of less than 2 is usually achieved in optimal conditions17
The efficiency of
natural photosynthetic systems is limited by electron-hole recombination which is when the charge separation
25
process is not successful Even when this process is successful up to half of the energy from the excited state
of the chlorophyll is used2 Energy is also used by the organism to ensure other processes within the cell are
functioning The inefficiencies of natural photosynthesis highlight major areas where researchers are looking
to improve in artificial photosynthetic systems and are discussed over the next sections
Photodamage occurs in photosynthetic systems when solar energy cannot be effectively dissipated as heat or
be used to form photosynthetic products fast enough Upon photon absorption chlorophylls are excited to a
singlet state whereby under normal conditions the chlorophyll molecule will either pass the energy to another
chlorophyll molecule by FRET emit a photon or dissipate the energy as heat High levels of light increase the
amount of photosynthesis occurring as well as the amount of time chlorophylls spend in their singlet state
which increases the risk of chlorophylls forming longer-lived triplet states if the energy is not passed on or
dissipated fast enough Chlorophylls in their triplet state can photosensitise toxic chemicals such as singlet
oxygen which causes photodamage18
Natural photosynthetic systems limit photodamage with a process
called non-photochemical quenching using molecules called carotenoids that quench chlorophyll triplet states
by triplet-triplet energy transfer Carotenoids in their triplet state are low energy and quickly release their
energy through heat production and do not facilitate the production of singlet oxygen1213
This method of
photoprotection has been mimicked in artificial photosynthetic systems to extend their lifetimes and enable
them to work under intense light conditions
22 Current energy usage and definition of artificial photosynthesis
The current demand for energy is primarily met by the combustion of fossil fuel resources in the form of coal
crude oil and natural gas
26
Figure 22 shows that the energy demand has doubled over the last 40 years and it should be noted that this
demand is expected to double again by 205031719
The increased energy demand could be met by increasing
fossil fuel combustion However fossil fuel combustion is not a clean process and releases large amounts of
greenhouse gases such as carbon dioxide carbon monoxide and nitrogen oxides The accumulation of these
greenhouse gases in the atmosphere is increasing the average global temperature damaging the ozone layer
and causing more extreme weather2021
From these studies it is clear that using fossil fuels to meet the future
energy demand could cause irreversible damage to the environment and the human population2223
Due to
this much time money and resources are being dedicated to find clean stable and renewable energy
alternatives to fossil fuels2425
Current candidates include wind power tidal power geothermal power and
solar energy while the viability of nuclear power is currently under discussion due to the radioactive wastes
and potential emergency risks The majority of these technologies are currently expensive to operate
manufacture and maintain and produce rather small amounts of energy due to their low efficiencies This
report will focus on how solar energy is being utilised as a renewable energy source The sun provides
100x1015
watts of solar energy annually across the surface of the earth If this solar energy could be
harnessed with 100 efficiency the current energy demand for one year could be met within an hour In total
only 002 of the total solar energy received by earth over a year would be required161726
27
Figure 22 Worldwide consumption of fuel types by percentage Total fuel consumption was equal to 4667 Mtoe in 1973 and 9301
Mtoe in 2013 and is represented by the size difference of the two charts below The figure was adapted from The 2015 Key
World Energy Statistics report3 Mtoe = million tonnes oil equivalent This figure does not state whether the energy came
from a renewable source
Currently one of the best and most developed methods of utilising solar energy (photons) is by using
photovoltaic cells that absorb photons and generate an electrical current This electrical current can be
instantly used as a source of energy or it can be stored in a wide variety of batteries for later use There are a
number of disadvantages to solely relying on photovoltaics to provide us with all of our energy requirements
which are listed below
Photovoltaics can only be used in areas that have high year-round levels of sunlight
The electrical energy has to be used immediately (unless it is stored)
Batteries used to store electrical energy are currently unable to store large amounts of energy have short
lifetimes and their production generates large amounts of toxic waste materials
To address these disadvantages researchers are looking into ways that solar energy can be stored as
chemical energy instead of inside batteries as electricity This is the point where the research being conducted
begins to draw inspiration from photosynthetic organisms14
Photosynthetic organisms have been capable of
utilising solar energy to generate a multitude of complex molecules for billions of years27
Natural
photosynthetic systems are capable of producing two main fuel types hydrogen and carbon-based fuels
Hydrogen is generated from photon-driven in PSII and carbon-based fuels such as carbohydrates and lipids
are generated from the reduction of carbon dioxide with hydrogen (Calvin cycledark reactions)1628
Hydrogen
and carbon-based fuels are the main fuel types researchers aim to produce using artificial photosynthetic
systems29
Hydrogen is produced by splitting (oxidising) water with solar energy catalysts and water oxygen
is a by-product of water oxidation Hydrogen is the simplest fuel to produce and the majority of the
technologies discussed in this report have already had success producing it It is desirable however for
researchers to generate more complex carbon-based fuels such as carbon monoxide methane methanol and
higher order carbon-based compounds using solar energy carbon dioxide and water because carbon-based
fuels have a higher energy density than hydrogen and are used as our primary energy source It should be
noted that hydrogen does not exist in its molecular form in nature which means that it must be produced by
an energy input Hydrogen is most commonly produced by steam reforming natural gas or fossil fuels such as
propane diesel methanol or ethanol8 These methods produce low purity hydrogen and consume fossil fuels
so they do not relieve any fossil fuel dependencies and they further contribute to environmental concerns
In later sections of this literature review some of the main technologies that utilise artificial photosynthesis to
generate fuel molecules are discussed These technologies offer a potential method by which high purity
hydrogen can be produced by the water-splitting reaction using energy obtained from renewable sources
Hydrogen carbon monoxide and carbon dioxide are important feedstocks for making industrial products such
as fertilisers pharmaceuticals plastics and synthetic liquid fuels With more research it is hoped that it will
soon be possible to produce complex molecules from chemical feedstocks that have been produced using
28
renewable energy Technologies that directly convert solar energy to electrical energy (photovoltaics) have
been commercialised for a number of years and can generate electricity on a megawatt scale at large
facilities Success has also been gained with generating hydrogen with a number of technologies such as
biological hybrid systems photoelectrocatalysis and electrolysers (some sub-technologies in this pathway
have been commercialised and can produce power on a megawatt scale) which will also be discussed in this
literature review Some success has been had with generating these more complicated molecules by artificial
photosynthesis from chemical feedstocks but it should be noted that these technologies are still at an early
research and development stage Using recent literature a definition for artificial photosynthesis was
developed for this study and is provided below
Artificial photosynthesis is a process that aims to mimic the physical chemistry of natural
photosynthesis by absorbing solar energy in the form of photons and using the energy to
generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
This is a broad definition of artificial photosynthesis where the term physical chemistry includes any reaction
or process that takes place during natural photosynthesis The term fuel molecules encompasses the term
solar fuel and can include any molecule that the system has been designed to produce such as molecular
hydrogen hydrocarbons alcohols and carbohydrates Biomimetics refers to a system that aims to mimic a
biological system by including some aspects of a biological system such as photosystems I and II chlorophyll
molecules or the electron transport proteinsmolecules Nanotechnology can refer to systems that use organic
chemistry inorganic chemistry or surfaceinterface chemistry to generate artificial photosynthetic systems
Synthetic biology refers to biological systems that have been genetically engineered to either allow or prevent
a biological process to occur
To date much progress has been made in the development of artificial photosynthetic systems since the
conception of the term22628-35
The most common problems associated with artificial photosynthetic systems
arise from
Low efficiency
Inability to utilise the entire spectrum of photon wavelengths
Inability to efficiently separate the charged species
Most systems use expensive noble metals to conduct the chemistry36
Short device lifetimes
Should these synthetic fuels be produced at a large enough scale for commercial use a new set of problems
would appear associated with how the fuels should be stored and distributed Using artificial photosynthesis to
generate hydrocarbons that are already used as an energy source would require fewer infrastructural changes
than switching to a hydrogen economy Furthermore the production process needs to be easily scalable so
that fuels can be produced in a cost-effective way on a terawatt scale in a manner that can keep up with the
ever-increasing energy demand In the next section several different types of artificial photosynthesis
technologies are introduced that aim to effectively utilise solar energy
29
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the
study
Research and development related to the area of artificial photosynthesis encompass several technological
areas The different pathways for artificial photosynthesis are illustrated in
30
Figure 22 along with some of the compounds that can be generated from these technologies on their own or
by combining them It should be noted that while Figure 23 presents a broad selection of potential compounds
that can be produced the actual number of compounds that could potentially be generated by artificial
photosynthetic systems is limitless
Figure 23 Different routes by which artificial photosynthesis can take place and the products that can be generated by utilising the
different technologies This image was generated by The University of Sheffield PV = Photovoltaics
The efficiency and usefulness of artificial photosynthetic technologies are dependent on how well they can
perform three distinctive steps that are found in natural photosynthetic organisms namely
How efficiently they are able to capture incoming photons (percentage of the spectrum that can be
utilised)
How efficiently the system can transfer the energy to a reaction centre (minimising energy loss during the
transfer)
How well the system can generate and separate charges to allow the desired chemical reaction to take
place (preventing charge recombination)
The complexity of artificial photosynthetic systems occurs when multiple charges have to be separated for a
chemical reaction to occur The production of hydrogen and oxygen from the water-splitting reaction which is
probably the simplest reaction these systems must be capable of still involves the transfer of four electrons
and the generation of more complicated compounds will require even more charge-separation events to occur
The following sections discuss the artificial photosynthetic technologies as depicted in
31
Figure 22 which are synthetic biologyhybrid systems photoelectrochemical catalysis and co-electrolysis
231 Synthetic biology amp hybrid systems
This pathway aims to take existing biological systems that perform different stages of photosynthesis such as
the light-harvesting charge separation or molecule synthesis steps and combine them so they are able to
produce specific fuel molecules These biological molecules can be modified or combined with other biological
molecules or synthetic organicinorganic compounds so that they are able to produce specific fuel molecules
more efficiently It is known that natural photosynthetic systems contain a number of crucial components that
need to be included in synthetic biology and hybrid artificial photosynthetic systems For example they should
contain a light harvester (semiconductor or molecular dye) a reduction co-catalyst (hydrogenase mimic or
noble metal) and an oxidation co-catalyst (photosystem II mimic that is capable of producing molecular oxygen
and hydrogen) It should be noted that these technologies are at a very early stage of development
(laboratory level technology readiness level (TRL 1-4)) and are many years away from being commercialised
Briefly researchers are capable of producing small quantities of hydrogen through the water-splitting reaction
and have demonstrated the reduction of carbon dioxide to methane and acetate Researchers are also
investigating the possibility of using basic cells (biological) to host biological machinery that is capable of
generating more complex fuel molecules The long-term goal of these technologies will be to reliably generate
large quantities of specific fuel molecules from simple starting compounds such as hydrogen and carbon
dioxide which are combined and converted into a series of different compounds using a series of enzymes
and synthetic organic and inorganic catalysts
232 Photoelectrocatalysis of water (water splitting)
This pathway aims to develop efficient photovoltaics and photoelectrochemical catalysts that utilise earth-
abundant metals capable of generating oxygen and hydrogen through the water-splitting reaction38
Photovoltaics can be used to generate electrical energy directly from sunlight Photovoltaicssemiconductors
can be used in photoelectrochemical cells to produce hydrogen from the water-splitting reaction PVs and
PECs are among the most advanced areas of artificial photosynthesis Photovoltaics utilise semiconductor
materials that are capable of directly generating electrical currents (electrical energy) when exposed to certain
wavelengths of light These semiconductors have to be capable of utilising a range of photon wavelengths
efficiently and must have long lifetimes Photovoltaics have been commercialised and are producing power on
a megawatt scale Future developments in this field aim to increase device efficiency and lower the costs
associated with them (TRL 7-8) Photoelectrochemical cells are capable of producing electricity and fuel
molecules when exposed to certain wavelengths of light Fuel molecules such as hydrogen are produced by
electrolysing water (splitting water) which could provide an unlimited source of hydrogen that could be used to
generate power or reduce carbon dioxide Water-splitting cells require semiconductors that are able to support
rapid charge transfer at the semiconductoraqueous interface have long-term stability in aqueous
environments and are capable of utilising a range of photon wavelengths30
233 Co-electrolysis
This pathway provides an alternative method by which water oxidation can be performed Alkaline
electrolysers and polymer electrolyte membrane electrolysers have been mature technologies now for a
number of years and are capable of converting water and electricity to hydrogen and oxygen The co-
electrolysis pathway aims to use carbon dioxide-water co-electrolysis to generate syngas (COH2) which is
produced by simultaneously reducing carbon dioxide and water using high temperature solid oxide cell
electrolysers (SOECs)39
Syngas can be used to generate simple intermediate compounds that can be used
as feedstock for more complicated chemicals used in fertilisers pharmaceuticals plastics and synthetic liquid
fuels Methanol is an example of a simple molecule that can be made from syngas The dehydration of
methanol can be used to generate the cleaner fuel dimethyl ether which is being considered as a future
energy source40
As a technique to produce power co-electrolysis offers a number of advantages over other
techniques such as photovoltaics and wind power in that it is not site-specific and can continuously generate
32
power However these devices require large amounts of electricity to function which affects their operating
costs It is likely that these systems will have their electricity supplied to them by solar or wind power farms in
the near future
33
3 Assessment of the technological development current status and future perspective
This literature review will focus on three technologies (synthetic biologybiological hybrid systems
photovoltaicsphotoelectrochemical cells and co-electrolysis) that are currently using artificial photosynthesis
to generate energy in the form of electricity and fuels The majority of research into these technologies has
focused on improving device efficiencies lifetimes and producing hydrogen The review will conclude with
discussions about the fuels researchers are currently producing potential large-scale facilities to produce the
fuels and finally the potential directions research into artificial photosynthesis could pursue Figure 3 shows a
general development and supply chain for technologies that aim to use artificial photosynthesis to convert
solar energy into power and fuels It should be noted that each technology will have its own set of specific
challenges which will be discussed at the end of each respective section This literature review was
constructed using material from a number of sources such as peer-reviewed journals official reports and
patents that have been filed
Figure 31 General development and supply chain for technologies that aim to use a combination of photovoltaics and
photoelectrochemical cell artificial photosynthetic technologies to convert solar energy into power and fuels
34
31 Synthetic biology amp hybrid systems
311 Description of the process
Artificial photosynthetic systems that utilise synthetic biology aim to modify existing natural photosynthetic
systems at the genetic level or combine them with other biological systems and synthetic compounds to
produce a specific fuel or improve efficiency It should be noted that technologies based on using synthetic
biology and hybrid systems to produce solar fuels are still at the research and development stage (TRL 1-4)
however the use of these systems to produce a limited number of fine chemicals is more advanced with a TRL
3-7 The majority of technologies developed in this pathway have focused on producing hydrogen and only a
limited number of technologies are capable of producing more complex fuel molecules It should also be noted
that most of these systems are only capable of producing small amounts of fuel molecules for a short period of
time Natural photosynthetic systems can be broken down into three distinct processes that these systems
have to mimic light-harvesting energy transfer and charge generationseparation (catalytic reactions)1437
For
these technologies to be successful the systems have to be designed so that they consist of electron donors
and acceptors and attempt to mimic light-driven charge separation2 Generally these technologies aim to
combine biological molecules that have catalytic activity (enzymes such as PSI [NiFe]-hydrogenase and
[FeFe]-hydrogenase) or combine the enzymes with synthetic inorganic and organic compounds9 Examples of
when these systems have been successfully created are discussed below with figures and the TRLs of the
technologies are given after each technology has been discussed
Illustrations
Figure 32 A simplified diagrammatic representation of a PSI-platinum hybrid system that is used to generate H2 can be found below
showing PSI P700 chlorophyll a apoprotein A1 (red) and PSI P700 chlorophyll a apoprotein A2 (blue) The electron provided
by ascorbate is transferred to a cytochrome c6 where a photon excites the electron which is then passed through PSI where
it is transferred to the platinum (Pt) catalyst to generate molecular hydrogen This figure drew inspiration from Fukuzumi
2015 and Gorka et al 20149
35
Figure 33 A diagrammatic representation of a FeFe-hydrogenase I ndash cadmium sulphur (CdS) hybrid system that is used to generate
H2 The faded red structure represents the surface topography of FeFe-hydrogenase I the blue arrows represent the
movement of the electrons through the Fe-S clusters where hydrogen ions are converted to H2 and the yellow structures
represent the CaI capped CdS nanorods The figure was constructed using inspiration from Wilker et al 2014 using the
PBD file 3C8Y and edited using PyMol software12
312 Current status review of the state of the art
The first example of researchers successfully producing light-driven hydrogen from an artificial complex
composed of biological molecules and platinum was achieved by combining the PSI subunit PsaE from
Thermosynechococcus elongtus with an oxygen tolerant [NiFe]-hydrogenase from Ralstonia eutropha H16 to
form a PSI-hydrogenase complex This complex in presence of ascorbate (electron donor) was capable of
light-driven hydrogen production at a rate of 058 microM (mg chlorophyll)-1
h-1
41-43
(TRL 3)
Hydrogenases are enzymes that catalyse the reversible oxidation of molecular hydrogen while platinum is
also capable of reversibly photocatalytically oxidising hydrogen44
Researchers recently showed that when a
platinum nanocluster was attached to a PSI molecule the complex was able to produce hydrogen at a rate of
673 microM (mg chlorophyll)-1
h-1
- the general structure of this complex is highlighted in Figure 323
Systems
based on these original concepts have been optimised to achieve higher hydrogen production efficiencies of
up to 244 microM (mg chlorophyll)-1
h-1
It should also be noted that the electron donor (ascorbate) had to be
present in excess in both cases2345
It should also be noted that these hydrogen production rates are
comparable to those of natural photosynthetic systems which occur at a rate of ca 300 microM (mg chlorophyll)-1
h-1
46
(TRL 3-4)
Researchers recently proposed a model by which hydrogen can be generated using CaI capped CdS
nanorods The authors reported that light is absorbed by the CdS nanorods to excite two electrons which are
then transferred into the CaI cap where the two electrons are used to reduce two protons (H+) and generate
hydrogen (electrons are replaced in CdS by ascorbate) In a recent publication the authors showed that it is
possible to combine the CdSCaI nanorods with [FeFe]-hydrogenase in place of PSI (ascorbate is used as an
electron donor) In this biomimetic system the electrons are transferred to [FeFe]-hydrogenase where they
reduce H+ to hydrogen This system was shown to have a quantum efficiency of 20 be active for up to 4
hours and had a total turnover of 106 hydrogen before activity was lost The loss in activity was found to be
due to the inactivation of the CaI cap at the end of the CdS rod147
36
Figure 3 represents the system and process described above where the blue arrows represent the movement
of electrons from the CdSCaI nanorods to the iron-sulphur clusters in [FeFe]-hydrogenase (TRL 3-4)
Researchers were recently able to produce hydrogen using a PSI-cobaloxime complex when it was
illuminated with natural light Cobaloximes are vitamin B12 mimics capable of catalysing H+ reduction
Cobaloximes offer a number of advantages over hydrogenases in that they are not sensitive to oxygen their
synthesis is relatively simple and they are constructed from relatively cheap materials In this system sodium
ascorbate used a sacrificial electron donor and cytochrome c6 transported the electrons to the PSI-cobaloxime
complex Upon light absorption the electrons were excited and transported through PSI to the bound
molecular catalyst cobaloxime where hydrogen production occurs27
The maximum rate for the photoreduction
of water by this hybrid system was measured to be 170 mol hydrogen (mol PSI)-1
min-1
as was reached within
10 minutes of illumination It should be noted that after 90 minutes hydrogen production levelled off giving a
total turnover of 5200 mol hydrogen mol PSI-1
27
It is thought that the activity of the hybrid decreased due to
the dissociation of cobaloxime from PSI research efforts are currently underway to stabilise the hybrid
system27
This system is of particular merit because the PSI-cobaloxime hybrid is composed of earth-
abundant materials unlike the hybrid systems containing precious metals It should also be noted that there
are multiple molecular catalysts for hydrogen production other than the cobaloximes that can offer improved
stability solubility in water and better activity and have been discussed in a recent review6 (TRL 3-4)
The production of hydrogen at a rate of 2200 plusmn 460 micromol mg Chl-1
h-1
(a faster rate than natural photosynthetic
systems) has recently been demonstrated This was accomplished by generating a hybrid system consisting
of a PSI complex tethered to a [FeFe]-hydrogenase using a 18-octanedithiol nanowire and also crosslinking
cytochrome c6 to the PSI complex This four component system was then placed in a sodium phosphate buffer
containing the electron donor sodium ascorbate at pH 65 and illuminating the sample with natural light48
The
authors also reported results for complexes consisting of different nanowire lengths (3-10 carbons) and a
chain length of 8 carbons was found to give the highest hydrogen production rates this is most likely due to
the chain being long enough to minimise steric hindrance between the two proteins The hybrid system
retained its activity for up to four hours and it should be noted that the decrease in activity was attributed to
depletion of the electron donor (full activity was regained upon replenishing the ascorbate) It should also be
noted that the hybrid system regained its full hydrogen-evolving activity after being stored in anoxic conditions
at room temperature for 100 days48
(TRL 3)
The technologies above are only a few examples of the methods researchers have used to generate hydrogen
from hybrid systems Table 31 below summarises hydrogen production rates by a number of different hybrid
systems that all incorporate PSI into their complex The information in Table 31 was originally summarised by
Utschig et al 20156 All of the technologies in this table have a TRL of 3-4
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
PSI-catalyst system Rate of H2 production
[mol H2 (mol PSI)-1 s
-1]
TON (time hours)
PSI-nanoclusters photoprecipitated long liveda 49
0002 ndc (2000)
PSI-[NiFe]-hydrogenase genetic fusion 41
001 ndc (3)
PSI-nanoclusters photoprecipitated short-liveda 49
013 ndc (2)
PSI-[FeFe]-hydrogenase-PetF in vitro complexb 50
031 ndc (05)
PSI-Ni diphosphinea 51
073 (3)
PSI-[FeFe]-hydrogenase-Fd protein complexb 50
107 ndc (1)
PSI-molecular wire-Pt nanoparticlea 52
11 (12)
PSI-NiApoFd protein deliverya 51
125 (4)
PSI-cobaloximea 27
283 (15)
PSI-Pt nanoparticlea 45
583 (4)
PSI-molecular wire-[FeFe]-hydrogenasea 48
524 ndc (3)
a Redox mediator Cyt c6
b Redox mediator PC
c nd not determined
37
Researchers have generated a hybrid photocatalyst system capable of splitting water to produce hydrogen
and oxygen and capable of reducing carbon dioxide by rational design The system uses a semiconductor as
the light harvester and a biomimetic complex mimicking photosystem I as a molecular catalyst37
This work
highlights that the understanding of artificial photosynthetic systems is increasing as rational design can now
be used to construct biomimetic artificial photosynthetic systems (TRL 2)
Unicellular organisms such as Chlamydomonas reinhardtii are a type of green algae that can produce
hydrogen light-dependently using the enzyme [FeFe]-hydrogenase However hydrogen production rates in
photoactive organisms are limited by a number of physiological constraints This is due to electrons
generated by PSI being used in a number of reactions other than hydrogen production5354
Most photoactive
organisms will contain a form of photosynthetic electron transport ferredoxin (PETF) protein which provides
photosynthetic electrons generated by PSI for a number of metabolic pathways All of these pathways
compete for electrons with [FeFe]-hydrogenase Researchers recently genetically modified the affinity PETF
has for PETF-dependent ferredoxin-NADP+-oxidoreductase (FNR) without comprising the affinity PETF has
for [FeFe]-hydrogenase In this modified system PETF is still able to supply [FeFe]-hydrogenase with
electrons that it used to produce hydrogen but is less able to supply electrons to FNR which means that fewer
carbon dioxide fixation reactions occur Hydrogen production rates increased by nearly 5x in wild type cells
that had modified PETF53
(TRL 3)
Microbial biocathodes consist of an electrode that has electrochemically active microorganisms immobilised
onto its surface which are capable of reducing protons to hydrogen These systems offer a number of
advantages in that the cathode can be constructed from cheap materials and the microorganisms can self-
regenerate55
The first microbial biocathode consisted of three phases (1) acetate and hydrogen are oxidised
at a bioanode that has been inoculated with a mixed culture of electrochemically active microorganisms to
release carbon dioxide (2) only hydrogen is fed into the bioanode (3) the polarity of the cells is reversed
(direction of electron flow) and hydrogen production begins at the cathode55
Initially after the polarity is
reversed methane was produced at the biocathode and not hydrogen (TRL 4)
Bio-catalysed electrolysis is a microbial fuel cell-based technology that is capable of generating hydrogen and
other reduced products from electron donors (acetatewastewater) however these systems require an
external power source56
In this system acetate is oxidised at the anode by microorganisms in the presence of
high concentrations of ammonium and the electrons are transferred to a platinum catalyst (cathode) where
they reduce protons to hydrogen56
(TRL 3)
A recent paper has reported the reduction of carbon dioxide to acetate and methane using a water-splitting
reaction to produce hydrogen and sodium bicarbonate as the carbon source using microbial electrosynthesis
(MES)57
This system used an assembly of graphite felt and a stainless steel cathode This paper is important
because it presents the use of electrode materials derived from earth-abundant elements showcasing them
as particularly suitable for industrial scale-out due to their low cost (TRL 3)
Researchers at the University of Oxford developed a biological tool called ldquoSimCellrdquo A SimCell is a simple
non-replicating cell that has no well-defined function until a plasmid containing DNA coding a specific
function is inserted into the cellrsquos genome The inserted DNA could potentially provide all of the genetic
information needed by the cell to produce the proteins and enzymes required to produce specific fuel
molecules The SimCell has been optimised to be simple so that most of the energy the cell is using will go
towards carrying out the function of the newly inserted gene instead of maintaining numerous intracellular
processes5859
The SimCell could allow researchers to insert genetic information that codes the production of
target fuels thereby greatly increasing the number of potential fuel targets and the efficiency with which they
can be produced It is possible that this technology could be patented once it reaches a higher level of
maturity and a working system is demonstrated (TRL 1)
38
313 Future development main challenges
Synthetic biology amp hybrid artificial photosynthetic systems primarily focus on producing hydrogen however
research focused on the production of hydrocarbons using technologies such as MES is gaining momentum
Although these technologies are currently at the laboratory research and development stage (TRL 1-4) they
are improving quickly At a very small laboratory scale the systems are becoming efficient enough to produce
hydrogen at a rate that is comparable to that which occurs in natural photosynthesis although some
researchers have reported even faster production rates
Synthetic biology amp hybrid systems need to address a number of specific challenges before they can be
considered as commercially viable options for producing solar fuels Below some preconditions and
challenges regarding certain such systems are described
Protein Hybrid Systems
For proteins to be active their primary amino acid sequence must fold and adopt the correctly folded
structure Misfolded proteins can exhibit severely diminished activities
Proteins (and enzymes) are inherently unstable and sensitive to the pH temperature pressure and buffer
components and will often degrade over time which limits their use
Most hydrogenases are sensitive to oxygen so they must be kept under anaerobic conditions
Biological molecules can be produced at a large scale as shown by the biopharmaceutical industry
However the amount of biological molecules needed to produce the amount of fuel required to support
mankind would be huge and has not been calculated
One of the strongest properties of enzymes is that they exhibit a high level of specificity they are able to
produce specific molecules of high purity
Enzymes can be redesigned to give them new or improved functions within different environments60
However modifying protein and enzyme function is not trivial it is often a time-consuming process that
requires thorough understanding of the system although predictive tools for protein engineering are
improving
Enzymes are often very large molecules in which only a small percentage of the amino acid residues are
actively involved in catalysis Researchers could reduce the complexity of biological systems drastically if
they focused on stripping the enzyme down so it contains only the residues and cofactors needed for
catalytic activity on a simplified base framework of amino acids
Microorganisms
In a recent paper researchers investigated how hydrogen production can be enhanced and suppressed in
vitro They state that the main limitations of hydrogen production in microorganisms are the systemrsquos
sensitivity to oxygen and the competition between hydrogenases and NADPH-dependent carbon dioxide
fixation If these issues can be solved the technologies would be closer to commercialisation50
It should be
noted that microorganisms are capable of producing a number of fine chemicals on a commercial scale (these
are often produced in smaller amounts)
Microorganisms are highly complex in that a multitude of chemical reactions must take place so that the
organism can continue to function at the most basic level These extra reactions are major drawbacks if
these organisms are to be used to produce fuel molecules as most of the absorbed energy cannot be
used to produce the fuel molecules
To overcome this problem various aspects of the organismsrsquo genetic information can be modified to
minimise energy loss through side reactions
SimCells are simplified cells in that number of chemical reactions needed to sustain the organism are
minimised this means that more energy can dedicated to fuel production However these technologies
are currently in early stages of research and development and are not close to being produced on an
industrial scale
39
It is likely that fuel-producing microorganisms will have to be capable of expelling the fuel molecules
otherwise the fuel-producing cells will have to be destroyed to obtain the molecules
A major advantage of bacterial systems is that their genetic information can be modified so that they
produce a number of different fuel molecules However this is not a trivial task and the microorganisms
may not be able to survive when large concentrations of the fuel molecules are present
Bacterial cells can survive in a number of harsh conditions and they do not have to be in an ultra-clean
environment
Synthetic biology and hybrid systems face a unique challenge in that these systems are made by or are
genetically modified organisms (GMOs) GMOs are often subject to negative media attention and are often
portrayed and viewed to be unsafe by the public which means that the public may not want their fuel coming
from this source Some of the concerns surrounding the use of GMOs are valid and need to be investigated
One of the main concerns about the use of GMOs pertains to whether the GMO could have a severe effect on
the environment if it managed to migrate into the wild However this issue could be addressed by only using
GMOs that are not able to replicate (ie they are obtained from a secured parent cell) However most of the
concerns the public may have regarding GMOs could be solved by educating about GMOs and providing a
large body of scientific evidence that supports their safety
It should be noted that the authors could find no relevant patents for artificial photosynthetic technologies that
utilise synthetic biology amp hybrid systems
In conclusion synthetic biology amp hybrid systems that produce solar fuels are currently in the laboratory
research and development stage and it is too early to determine whether they would be a commercially viable
option However current research is promising and shows that they could be a valuable part of generating
solar fuels due to their high level of specificity and ability to be reengineered to carry out new and specialised
chemistry
32 Photoelectrocatalysis of water (water splitting)
321 Description of the process
This pathway aims to develop efficient photovoltaics and photoelectrocatalysts that utilise earth-abundant
metals capable of generating oxygen and hydrogen by splitting water38
The water-splitting (water oxidation)
reaction is one of the most advanced areas of artificial photosynthesis These systems that directly produce
fuel molecules from sunlight are currently in the early researchproof-of-concept stage (TRL 2-4) This means
that they are a number of years away from being a commercially viable method to produce synthetic fuels31
Water oxidation involves the removal of 4e- and 4H
+ to generate molecular oxygen (O2) and molecular
hydrogen (H2) In nature water oxidation is carried out by photosystem II in natural photosynthetic systems
The water-splitting reaction has the potential to provide a clean sustainable and abundant source of
hydrogen that could be used as energy or to reduce carbon dioxide to higher order hydrocarbons which is
why a considerable amount of time and money has been spent trying to improve the process
Photovoltaic cells (PVs) also known as solar cells utilise semiconductor materials that are capable of directly
generating electrical currents when exposed to certain wavelengths of light Light absorption by the
semiconductor promotes an electron from the low energy valence band to the higher energy conduction band
This creates an electron-hole pair that can be transported through the electrical device to provide power
Research focusing on PVs has focused on improving their efficiencies Initially efficiencies lt1 were
obtainable but the most recent generation of PVs can achieve efficiencies gt45 Research has shown that
the efficiencies of PVs can be greatly improved by using multi-junction instead of single-junction devices60
Efficiencies of different PV models have increased over the last 40 years this plot is courtesy of the National
Renewable Energy Laboratory Golden CO The most recent PVs have long lifespans (gt20 years) low
40
pollution levels and low operating costs30
However PVs do have some drawbacks in that they are expensive
to manufacture can only be used during the day in areas that receive a lot of sunlight utilise a fraction of the
available spectrum and it is problematic to store the energy in batteries3360
Problems associated with long-
term storage of energy could be overcome by storing the energy in chemical bonds of molecules such as
hydrogen alcohols and hydrocarbons which is why the research in the following section is of importance It
should also be noted that PVs have a TRL of 9 as they have been successfully commercialised and can
provide power on a megawatt scale
Photoelectrochemical cells (PECs) are capable of producing fuel molecules when exposed to certain
wavelengths of light or paired with a semiconductor (PV) Hydrogen can be produced by the water-splitting
reaction Figure 3 shows a schematic diagram of a PEC which is capable of conducting water oxidation in
two separate chambers Currently there are two primary methods by which solar fuels can be generated from
the water-splitting reaction in PECs The first is by direct photoelectrocatalysis at the semiconductor-
electrolyte interface (occurring at a solid-liquid junction) and the second is by coupling the electrochemical
(PEC) reaction directly to a buried p-n junction PV230
Both of these approaches require the generation of a
photovoltage sufficient to split water (gt 123 V)30
Photoelectrodes in PECs must have high surface stability
good electronic properties and suitable light absorption characteristics Water-splitting cells require
semiconductors that are able to support rapid charge transfer at the semiconductoraqueous interface have
long-term stability in aqueous environments and are capable of utilising a range of photon wavelengths30
These functions are obtained by using multi-junction configurations that use p- and n-type semiconductors
with different band gaps and surface-bound electrocatalysts The brief description of PVs has been included
because they are an essential component for a number of systems that photocatalytically split water
Illustration
Figure 34 The illustration below shows a photoelectrochemical cell capable of water oxidation using solar energy consisting of
separated titanium dioxide (TiO2) and platinum (Pt) electrodes Water oxidation occurs at the TiO2 electrode where oxygen
is formed during which process protons (H+) and electrons (e
-) are released H
+ pass through an ion transport membrane to
a compartment containing the Pt electrode where electrons are used to reduce H+ to hydrogen After this hydrogen can be
stored as an energy source or it can be used to reduce carbon dioxide to higher order hydrocarbon compounds
Explanations
According to the National Renewable Energy Laboratory the greatest gains in efficiency have been made with
the multi-junction PV cells The first single-junction GaAs cells developed in the mid-1970s and had
efficiencies of ca 22 (which is better than most of the more recent PV cells that have been developed) The
most recent multi-junction technologies have achieved efficiencies of up to 46 It should also be noted that a
41
greater number of p-n junctions a PV has the greater its efficiency This is because each p-n junction is made
from a different semiconductor material that can absorb light at a different wavelength increasing the amount
of the spectrum that can be utilised PVs based on crystalline silicone cells have shown a slow increase in
efficiency over the last 40 years starting from 14 and increasing up to 276 PVs utilising thin-film
technologies now achieve efficiencies up to 223 Thin-film technologies are a particularly promising branch
of PV due to them being lightweight and the potential to manufacture them by printing which would decrease
their production and installation costs
Figure 3 shows a schematic diagram of a PEC cell that was developed by Honda and Fujishima in 1972 and
was capable of the water-splitting reaction using a TiO2 electrode in tandem with a platinum electrode61
PEC
cells consist of three basic components a semiconductor a reference electrode and an electrolyte The
principles of PEC cell operation are simple a photon is absorbed by the semiconductor (TiO2) material which
causes electron excitation and the excited electrons move to the reference electrode (Pt) through a metal
wire The movement of electrons between the two materials generates a positive charge (holes) at the
semiconductor which combines with electrons in the oxygen molecules of water to form molecular oxygen
and hydrogen ions At the reference electrode the electrons can combine with hydrogen ions to form
molecular hydrogen In this study oxygen was generated at the TiO2 electrode and hydrogen was generated at
the platinum electrode
Since the initial study by Honda and Fujishima researchers have spent much time developing new materials
for anodic and cathodic processes that are capable of carrying out the same process with greater efficiency
and ability to produce more products3061
Currently the cost-effectiveness of using solar energy systems to
generate power and fuels is constricted by the low energy density of sunlight which means low cost materials
need to be developed so that enough sunlight can efficiently be captured Sunlight availability is intermittent
which means that the captured energy needs to be efficiently stored The efficiency of PEC water-splitting
devices is determined by measuring their solar-to-hydrogen (STH) efficiency this is defined as the amount of
chemical energy produced in the form of hydrogen divided by the solar energy input without the use of any
external bias10
322 Current status review of the state of the art
Currently there are two main approaches that are used to photocatalytically split water into oxygen and
hydrogen The first method utilises a single-visible-light photocatalyst (this is essentially a PV) with a narrow
band gap capable of absorbing photons in the visible spectrum has a suitable thermodynamic potential for
water splitting and is stable enough to avoid photocorrosion4 The drawbacks of this system include that it is
only capable of utilising a small region of the spectrum and the collection of oxygen and hydrogen is difficult
due to them being produced in the same region2 The second method uses a two-step mechanism which
utilises two photocatalysts (photoanode and photocathode) in tandem similar to the Z-scheme present in
natural photosynthetic systems2 This setup enables the system to utilise a larger range of visible light
because the free energy required to drive each photocatalyst can be tuned compared to the one-step system
(one photon is needed for each photocatalyst) In this system the oxygen and hydrogen generated via water
oxidation can be separated more efficiently from each other because they are produced at different sites
(oxygen is produced at the anode and hydrogen is produced at the cathode) this also reduces the likelihood
of charge recombination462
This second system is more desirable as the oxygen and hydrogen evolution
sites can be contained in separate compartments62
Theoretical calculations have highlighted that the
maximum efficiency of a single absorber PEC system could reach 29-31 whereas a tandem PEC system
could reach 40-41 further highlighting the advantages of using tandem devices106364
Efficiency calculations
for three different PEC configurations a single photoabsorber system a dual stacked photoabsorber system
and a dual side-by-side photoabsorber system were reported to be 112 228 and 155 respectively
These systems differ in the spatial distribution and number of photoabsorbers which will affect the range of
wavelengths that can be absorbed and therefore the materialsrsquo STH efficiency10
It should be noted that the
practical efficiencies of these devices will often be much lower due to the inefficiencies associated with the
catalysts and reaction overpotentials10
These calculations show that the best way to achieve higher
efficiencies in PEC devices is to use a dual stacked photoabsorber system
42
Recently four PEC reactor types were conceived to represent a range of systems that could be used to
generate hydrogen from solar energy Each system design can be seen in Figure 31062
Types 1 and 2 are
based on relatively simple photoactive nanoparticle suspensions whereas types 3 and 4 are based on more
complex planar arrays a brief discussion of each system is given below It should be noted that quoted STH
efficiencies are optimised values and do not take into account material lifetimes
Figure 35 The figure below shows four PEC reactor types including a (a) Type 1 reactor showing the plastic bags containing the
suspended hydrogen- and oxygen-evolving photoactive particles (b) Type 2 reactor showing the plastic bags containing
separated suspensions of photoactive particles capable of separately evolving hydrogen and oxygen (c) Type 3 reactor
showing a sun-orientated panel containing a layered PEC cell capable of producing hydrogen and oxygen and (d) Type 4
reactor the design of which consists of a similar layered PEC cell to Type 3 with an added parabolic receiver that is able to
concentrate light onto the PEC cell throughout the day These figures were originally constructed by Pinaud et al 201310
Type 1 This reactor has the simplest design It consists of a transparent plastic bag that contains a
suspension of photoactive particles in 01 M potassium hydroxide that are capable of simultaneously
evolving hydrogen and oxygen by the water-splitting reaction Photons at a variety of different wavelengths
are able to penetrate the plastic bag whereas the electrolyte evolved gases and photoactive particles are
held within the bag The authors modelled the photoactive particles as spherical cores coated with
photoanodic and photocathodic particles The authors calculated that this reactor type could achieve a
realistic STH efficiency of 10 however it should be noted that the hydrogen and oxygen evolved in this
system would need to be separated1062
43
Type 2 The design of this reactor is very similar to that of Type 1 in that it consists of photoactive
nanoparticles suspended in an electrolyte contained within clear plastic bags The main difference
between the two systems is that the hydrogen- and oxygen-evolving particles are contained within
separate bags which reduces the need for a gas separation step and increases the safety of the system
However the bag design has to be more complicated in that a redox mediator is required along with a
porous bridge between the hydrogen- and oxygen-evolving bags The STH efficiency of this system was
calculated to be 51062
Type 3 This reactor is composed of a layered planar electrode consisting of multiple photoactive layers
(multi-junction PVsemiconductor) that is submerged within an aqueous solution containing 01 M
potassium hydroxide encased within a clear plastic case Multiple photoactive materials are used so that
more of the solar spectrum can be utilised The anode (oxygen evolution) is at the top of the cell where it
absorbs photons of a certain wavelength and allows others to pass through to the cathode where they are
absorbed into another layer to drive hydrogen evolution Due to the fixed orientation of these cells they
have to have a large surface area to ensure they can absorb the maximum amount of photons1062
Type 4 This reactor is similar to Type 3 in that it consists of a flat PEC cell of a similar design (gas
evolution occurs in a similar manner) The main difference is that a solar tracking concentrator system is
used to focus sunlight onto the PEC cell This means that smaller and more efficient PEC devices can be
used to reduce costs The STH efficiency of this system was calculated to 12-181062
The costs of hydrogen production for a power plant consisting of each reactor type were assessed (it should
be noted that costs for Type 3 and 4 plants were considered to be more accurate due to availability of PV
pricing)10
Type 1 $160 H2kg
Type 2 $320 H2kg
Type 3 $1040 H2kg
Type 4 $400 H2kg
During early work with PEC cells researchers were able to achieve efficiencies of 124 for hydrogen
production over 20 hours using a p-GaInP2(Pt)rsquoTJGaAs electrode However it should be noted that current
density decreased from 120 mAcm2 to 105 mAcm
2 over the course of the experiment which was caused by
damage to the PEC cell65
Therefore although this device was able to achieve high efficiencies its lifetime
was too low
Water oxidation in the presence of a photocatalyst that has been combined with a co-catalyst has been
reported2 The role of the co-catalyst is to provide extra reaction sites and decrease the activation energy for
oxygen and hydrogen evolution Researchers must carefully choose the type of co-catalyst to use this is
because although some noble metal catalysts like platinum and rhodium are good for enhancing hydrogen
production they also catalyse the reverse reaction (convert oxygen and hydrogen back to water)66
To
circumvent this issue transition-metal oxides are often used as co-catalysts instead of noble metals as these
do not catalyse water reformation However these compounds are often more susceptible to degradation
when they are exposed to the reactive environments found in PECs4
The first example of a metal oxide being used to split water into oxygen and hydrogen was carried out by a
dinuclear ruthenium complex (the blue dimer)34
Electrochemical and in situ spectroscopic measurements
were used to measure hydrogen production when platinum and rhodium plates deposited with chromia
(Cr2O3) were used as the water-splitting material4 Coreshell-structured nanoparticles that have a noble metal
or noble metal oxide core and a Cr2O3 shell have been shown to be capable of acting as a co-catalyst for the
water-splitting reaction This presents a mechanism by which noble metals could be used as co-catalysts the
Cr2O3 shell has been shown to supress the water reformation reaction when coated onto palladium and
platinum cores4 Multiple transition metal oxides such as NiOx RuO2 and TiO2 can be used as co-catalysts
when they are treated with appropriate chemicals (TRL 3-4)
44
Researchers recently reported a catalyst that was formed upon the oxidative polarization of an inert indium tin
oxide electrode immersed in a solution containing 100 mM potassium phosphate and 05 mM cobalt (II) ions at
pH 70 Upon initiation of electrolysis at 129 V oxygen production was shown to increase linearly over 12
hours to reach a maximum of 100 microM h-1
(after 12 hours electrolysis was stopped)67
The catalytic activity of
the reaction was also shown to be pH-dependent which suggests that the hydrogen phosphate ion is the
proton acceptor (TRL 3)
In a recent publication a multi-junction design was used to absorb light and provide energy for the water-
splitting reaction Multi-junction PVs are more efficient as they are able to absorb enough solar energy to
provide the free energy for water splitting The researchers developed a device based on an oxide
photoanode (Fe2O3 or WO3) and a dye-sensitized solar cell which performs unassisted water splitting with an
efficiency of up to 31 STH Incoming light was absorbed by the photoanode where the water-splitting
reaction and oxygen evolution takes place Electrons were transported to a platinum cathode where hydrogen
formation occurred68
(TRL 4)
Recently researchers demonstrated water splitting using tandem PEC cells where PtCdSCGSACGSe was
used as the photocathode (hydrogen evolution) and NiOOHFeOOHMoBiVO4 as the photoanode (oxygen
evolution) The cell was able to sustain a stable water-splitting reaction for 2 hours with an STH efficiency of
06769
(TRL 3)
Photochemical hydrogen production by nanowire arrays has been shown to be advantageous to more
traditional system designs because they use less precious material to produce7071
Researchers recently
showed that photoelectrochemical hydrogen production from water was possible using InP nanowire arrays In
these systems the chosen nanowire compound has a layer of silicone oxide (SiO2) deposited onto its surface
and then a co-catalyst deposited onto the surface of Efficiencies of 52 and 64 were obtained when the
InP nanowires were deposited with platinum and MoS3 respectively7072
Silicon is an abundant low-cost
semiconductor commonly used in PV devices and photoelectrochemical hydrogen generation at the
Sielectrolyte interface has been extensively studied for decades Hydrogen is evolved slowly at the
Sielectrolyte interface which has led to research efforts to modify the surfaces with electrocatalysts such as
platinum and ruthenium which are showing good activities and efficiencies71
(TRL 2-3)
323 Patents
Patents have been filed for systems based on nanoparticle suspensions and PECs some of which are
discussed below
A patent was filed in 2012 detailing a suspension of photoactive nanoparticles consisting of metallic cores and
semiconductor photocatalytic shells that can photocatalytically split water to directly obtain hydrogen The
efficient and unassisted photocatalytic splitting of water by the nanoparticles is based on resonant absorption
from surface plasmon in the metal coresemiconductor shell hybrid nanoparticles which can extend the
absorption spectra towards the visible-near infrared range This increases the solar energy conversion
efficiency When the photoactive nanoparticles are used in combination with scintillator nanoparticles the
hybrid photocatalytic nanoparticles can be used to convert nuclear energy into hydrogen73
(TRL 3-4)
A patent was recently filed for a PEC cell consisting of melanin melanin precursors melanin derivatives
melanin variants melanin analogues natural or synthetic pure or mixed with organic or inorganic compounds
metals ions drugs that act as the water electrolyzing material This technology uses solar energy as the sole
or main source of energy to produce hydrogen from water The system integrates a semiconductor material
and a water electrolyser inside a monolithic design that produces hydrogen directly from water using light
between 200 to 900 nm as the main or sole source of energy The technology aims to meet two criteria (i) the
system or light-absorbing compound should generate enough energy for the water-splitting reaction to be
45
completed and (ii) the materials need to be cheap to source and exhibit high stability in water and the reactive
environment The authors claim that all of these requirements can be met by melanin and related compounds
which represents a significant advancement in PEC design The technology can be used to generate
hydrogen oxygen and high energy electrons It can also be used to perform the opposite reaction and
generate water from electrons protons and oxygen and can be coupled to other processes generating a
multiplication effect It can also be used for the reduction of carbon dioxide nitrates and sulphates or others74
(TRL 2-3)
In 2008 a patent was filed describing a PEC system that could produce hydrogen from water The device was
comprised of (i) an electrolytic bath containing an electrode for catalytic oxidation an electrode for catalytic
reduction and an ion separation film disposed between the two electrodes immersed in an aqueous
electrolyte solution and (ii) a photoelectrode positioned outside the electrolytic bath and electrically connected
to the two electrodes This PEC system is characterised by disposing a photoelectrode at a position which
does not contact the electrolyte solution preventing the lowering of the photoelectrode activities and which
maximises hydrogen production efficiency75
(TRL 3)
In 2014 a patent was filed describing an invention that was able to generate hydrogen by
photoelectrocatalytic water splitting The system also incorporated an analysis-detection system The system
was composed of a photoelectrocatalytic water-splitting hydrogen generation device constructed from TiO2
nanorods (water splitting) a platinum cathode and a AgAgCl reference electrode submersed in a 05 M
Na2SO4 solution Results from five tests of the system were reported After the first hour the device produced
17-20 micromolh hydrogen for four hours as determined by the inbuilt detector76
(TRL 3)
324 Future development main challenges
The generation of electricity from solar energy by PVs has been successfully commercialised with the most
recent solar projects being able to produce electricity at a cost of 015 ndash 035 $kWh on a megawatt scale31
Facilities such as the Solar Star Power Station and the Topaz Solar Farm in the USA are examples of facilities
that use PV technologies that are capable of producing electricity (TRL 8-9) These facilities can now be
constructed because the cost of PVs has dramatically decreased and their efficiencies have increased over
the last few years Laboratory research is currently focused on further increasing the efficiency of PVs and
combining these systems with catalysts that are capable of generating higher order hydrocarbon fuels
However the reduction of carbon dioxide to liquid fuels is a complicated multi-electron process still in the
proof-of-concept stage (TRL 2-3) It is also recommended that the new materials PVs are constructed from
should ideally be cheap abundant lightweight flexible and robust If all of these requirements are met the
costs associated with manufacturing PVs as well as transporting installing and maintaining them may
continue to fall
There are a number of general challenges facing PEC technologies (including suspensions of photoactive
nanoparticles and PECs) that are associated with
Effectively designing facilities
Developing methods to store the generated energy
Developing transportation networks to distribute the energy
A major drawback of these facilities is that they can only be used during daylight hours when there is a clear
sky This highlights the importance of being able to store large amounts of energy at these facilities that can
be used outside of daylight hours It has been proposed that the energy generated from these facilities could
be stored in new types of batteries or as chemicals such as hydrogen and hydrocarbons Storing the energy
in the form of hydrocarbons would be particularly useful as these have a much higher energy density than
batteries and hydrogen The infrastructure to store and transport these already exists for them to be used as a
fuel However as previously mentioned the ability to convert hydrogen and carbon dioxide into high order
hydrocarbons using PVs and PECs is still in the proof-of-concept stage10
46
There are also a number of challenges related to the materials used to construct photoactive nanoparticles
and PECs This is particularly problematic because the most useful semiconductors are not stable in water
and the metal oxides that are stable in water often have band gaps that are too large for light absorption1065
There are three main processes that cause electrodes to degrade over long periods of time and inhibit their
activity
The first is corrosion which occurs with all materials over long periods of time
The second is catalyst poisoning which is caused by the introduction of solution impurities and it has
been shown that low concentrations of impurities can have a huge impact on electrode efficiency77
Finally changes to the composition and morphology (structurestructural features) of the electrode can
decrease their efficiency30
As well as exhibiting high stability the materials have to be highly efficient However there is a relationship
between device complexity cost and efficiency Water-splitters using triple-junction amorphous silicon or IIIndashIV
semiconductors have good efficiencies (5-10) but have high costs and device complexities Simpler
approaches using oxide-based semiconductors in a dual-absorber tandem approach have reported STH
conversion efficiencies up to 0368
This highlights the need to find cheaper and efficient semiconductor
materials that can be used for the water-splitting reaction
The US Department of Energy has determined that the price of hydrogen production delivery and dispensing
must reach $2-3 kg-1
before it can compete with current fuels2 It is also important to take into account the
infrastructural changes that would be required if we were to adopt a hydrogen fuel economy To meet the
current power demands of the US with PVs that have an efficiency of 10 a total area of 58000 miles2 would
be required The cost of semiconductors capable of these efficiencies amounts to tens of trillions of dollars
not taking into account the huge costs associated with the required changes to the infrastructure32
These
facilities would only be viable in areas where there is an abundance of sunshine (such as deserts) which also
proposes large fuel transportation issues In the majority of areas the sun is intermittent and only provides
about 6-10 hours of sunshine per day This further highlights the need to be able to store the energy in the
form of chemical bonds that can be used at any time as well as be more easily stored as batteries can only
store a relatively small amount of the energy required and can produce large quantities of toxic materials when
manufactured
It has been calculated that for the water-splitting reaction to provide one third of the energy required by the
human population in 2050 10000 solar plants each covering a 5 km x 5 km area (250000 km2 = 1 of the
Earthrsquos desert area) and with an overall efficiency of 10 would be required Each plant would be capable of
generating ca 570 tonnes of hydrogen from 5100 tonnes of water per day which together could provide up to
33 of the energy needed by mankind in 2050 The hydrogen could be transported directly to on-site
chemical plants where other organic compounds can be manufactured4 Figure 3 shows two diagrams of one
of these sites that could be capable of producing 570 tonnes of hydrogen per day24
The amount of each
material needed to generate methane from hydrogen and carbon dioxide is given in the formula below in
tonnes The US Department of Energy has set a target for hydrogen-producing PEC devices to have an STH
efficiency of 10 and a 5000 hour durability by 201878
120784119815120784 + 119810119822120784 rarr 119810119815120786 + 119822120784
120784(120784120790120787) + 120788120784120789120782 rarr 120784120784120790120782 + 120786120787120788
According to these calculations 6270 tonnes of carbon dioxide would be required by each of these plants per
day to use all of the hydrogen generated to produce 2280 tonnes of methane and 4560 tonnes of oxygen
The amount of carbon dioxide required increases linearly as the hydrocarbon chain length increases The cost
of manufacturing the number of PEC cells required to carry out this amount of water splitting would be in the
tens of trillions of euros taking into account the current costs of the associated technology62
The energy
required to power these facilities would be obtained from renewable sources such as wind wave and PVs
47
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting photoelectrochemical cells H2 generated
on-site could be used to reduce CO2 to higher order hydrocarbon fuel molecules These figures were constructed by Maeda
et al 2010 and Tachibana et al 2012
33 Co-electrolysis
331 Description of the process
Electrolysers capable of conducting the water-splitting reaction have existed for centuries Water electrolysers
are capable of converting water and DC electricity into gaseous hydrogen and oxygen according to the
equation below879
High-pressure (30 bar) water electrolysers have been commercially available since 1951
In 2012 there were at least 13 manufactures that produce low temperature water electrolysers (3 using
polymer electrolyte membranes (PEM) and 3 using alkaline electrolysers)79
Electrolysers that use solid oxide
electrolysers cells (SOECs) under high temperatures were first developed in the 1980s in the HotElly project
Currently SOEC technologies are still in the research and development stage It should also be noted that the
water splitting thermodynamics are more favourable at the higher temperatures used in SOECs as compared
to alkaline electrolysers PEMs and PECs ΔG = 237 kJ mol-1
(123 eV) at ambient temperatures ΔG = 183 kJ
mol-1
(095 eV) at 900 oC
8397980
120784119815120784119822 + 119811119810 rarr 120784119815120784 + 119822120784
Co-electrolysis is a technique that can be used to produce fuel molecules directly from electricity water and
carbon dioxide Interest in the electrolysis of water and carbon dioxide originated in the 1960s where it was
thought that the process could be used to supply oxygen for submarines and spacecraft81
Unlike electrolysis
co-electrolysis aims to simultaneously split water and reduce carbon dioxide to form a mixture of carbon
monoxide (CO) hydrogen and oxygen this process is highlighted in the equation below The term ldquosyngasrdquo
(synthesis gas) refers to a mixture of carbon monoxide and hydrogen and not the oxygen component
Producing fuels by co-electrolysis consists of three main stages carbon dioxide capture syngas synthesis
and storage of the renewable energy as chemical bond energy (hydrogen and hydrocarbon fuels)80
This
chemical reaction is achieved by using high temperature solid oxide cell electolysers3982-84
Co-electrolysis
offers a number of advantages over solar and wind power farms Solar and wind power farms have to be built
in site-specific areas to maximise their power output which limits the number of countries that would be able
to host these technologies (solar power is only viable for countries that have high levels of sun year-round)
Solar and wind power farms are only able to generate power intermittently which makes them unsuited to
coping with sudden large power demands (solar farms can only generate power during daylight hours) It has
been suggested that batteries and thermal fluids could be used to store energy for peak times However
48
these storage methods are currently unable to store large amounts of energy suffer from short lifetimes and
generate large amounts of harmful waste during production531
Technologies capable of co-electrolysing
water and carbon dioxide to syngas and hydrocarbons are at an early stage of development TRL 2-4
119810119822120784 + 119815120784119822 rarr 119810119822 + 119815120784 + 119822120784
It is also important to note that all electrolysers require a large input of electrical energy which would have to
be from renewable sources if this technology is to relieve its dependence on fossil fuels The major cost
associated with solid oxide electrolysis cells (SOEC) comes from the electricity required to operate them and
the feedstock while the cost of the electrolyser material makes up a smaller proportion of the total cost39
If
SOECs were designed to utilise wind and solar energy (PVssemiconductors) to generate the electricity they
require their operating costs would decrease significantly However this also decreases the number of
countries that could host electrolysers as their operation is again dependent on solar and wind energy It
would also be advantageous to incorporate a Fischer-Tropsch process that is capable of generating synthetic
hydrocarbons from the resulting syngas that can be used in the existing infrastructure3985
Syngas can be used to generate simple intermediate compounds that can be used as feedstock for more
complicated chemicals such as fertilisers pharmaceuticals plastics and synthetic liquid fuels Methanol is an
example of a simple molecule that can be made from syngas The dehydration of methanol can be used to
generate the cleaner fuel dimethyl ether which is being considered as a future energy source40
The most
common feedstocks for the production of hydrocarbon fuels are fossil fuels and biomass However it is hoped
that sustainable feedstocks such as carbon dioxide and water can be used to generate syngas which can be
converted into hydrocarbon fuels through Fischer-Tropsch synthesis39
Illustrations
Figure 37 A schematic diagram of water electrolysis being conducted in an alkaline electrolyser (left) and a polymer electrolyte
membrane electrolyser cell (right) to produce hydrogen and oxygen from water and DC electricity This figure was originally
produced by Carmo et al 20138
49
Figure 38 A schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell that produces hydrogen and
oxygen from water and DC electricity the reactions that occur at the electrodes are also shown This figure was adapted
from Meng Ni et al 20085
Explanations
Alkaline water electrolysis has been a mature technology for over 100 years (there were over 400 units in
operation by 1902) They have high efficiencies (47-82) and long lifetimes (15 years)1186
A recent
publication by Ursuacutea et al 2012 compiled a list of the main manufacturers of alkaline water electrolysers which
is shown in Table 3211
A number of advancements have been made regarding alkaline electrolysers over the last few years which
have focused on improving their efficiency to reduce operating costs and have increased the operating
current densities11
Other advancements include
Minimising the space between the electrodes to reduce the ohmic losses and allow the cell to operate at
current densities
Developing new materials to replace older diaphragms which exhibit higher stability and are better at
facilitating ion transport
Developing high-temperature (ca 150 oC) alkaline water electrolysers to increase the electrolyte
conductivity and promote the kinetics of the electrochemical reactions at the electrodesrsquo surface
Developing new electrocatalytic materials to reduce the electrode over-potentials this present a particular
difficulty for the anode because the oxidation half-reaction is most demanding
Alkaline electrolysers (Figure 3 left) consist of two electrodes that are separated by a gas-tight diaphragm
submersed in an electrolyte solution containing a high concentration of potassium hydroxide (20-30 wt) It
should be noted that electrolytes such as sodium hydroxide and sodium chloride can also be used in some
systems and they usually operate between 40-90 oC
11 Water is reduced at the cathode to generate hydrogen
gas and hydroxide ions (OH-) which diffuse through the diaphragm to the anode where they recombine to
generate oxygen and water811
The hydrogen and oxygen produced by alkaline electrolysers have purities
gt99
In PEM electrolysers (Figure 3 right) the electrolyte is constructed from a polymeric membrane with a cross-
linked solid structure permitting a compact system with greater structural stability (able to operate at higher
temperatures and pressures)8 The electrodes used in PEM electrolysers are usually constructed from noble
metals such as platinum and iridium which limits the scope of this technology as noble metals are of limited
abundance and expensive The unit consisting of the electrodes and polymer membrane is submersed in
water Water oxidation occurs at the anode where oxygen is formed and protons are transferred through the
50
polymer membrane to the cathode where they are reduced to hydrogen PEM electrolysers are able to
produce hydrogen and oxygen of even higher purity than alkaline electrolysers at ca 9999
It should be noted that the materials needed for the electrolyte and electrodes have to be cheap and easy to
manufacture on a large scale5 Water in the gas phase diffuses into the porous cathode where it dissociates
into hydrogen and oxygen at reaction sites81
At this point the hydrogen diffuses out of the cathode and is
collected The oxygen ions are transported through the electrolyte solution to the porous anode where they
are oxidised to oxygen and collected this process is demonstrated in Figure 35 The material chosen for the
cathode has to be able to support the diffusion of steam the reduction of steam and the diffusion of hydrogen
These requirements limit the number of suitable materials that can be used to noble metals such as platinum
and gold and non-precious metals such as copper and nickel However like the artificial photosynthetic
systems previously discussed the use of noble metals is unfavourable due to their rarity and high costs The
anode has to be chemically stable under similar conditions to the cathode which means that noble metals are
again candidate materials along with electronically-conducting mixed oxides5
Electrolyte This must be a chemically stable dense gas-tight material with good ionic conductivity and
low electronic conduction The electrolyte has to be stable enough to withstand the high temperatures
associated with the chemical reactions taking place It has to be gas-tight to limit the recombination of
protons and O- to hydrogen and oxygen respectively The electrolyte should also be as thin as possible so
as to minimise the ohmic overpotential5
Electrodes It should be noted that the following properties are the same for both the anode and cathode
The electrodes have to be porous enough to allow the transportation of hydrogen and oxygen and need to
have a similar thermal expansion coefficient to the electrolyte so as to limit the amount of mechanical
stress the components exert on each other They must also be chemically stable in highly
oxidisingreducing environments and high temperatures5
To ensure that the SOEC is operating at its maximum efficiency a number of parameters need to be
quantified this is often done through modelling the system Some of the parameters measured include the
composition of the cathode inlet gas cathode flow rate and cell temperature39
When generating syngas in a
SOEC the carbon dioxide is fed into the cathode side of the device where the hydrogen is generated
51
Table 32 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the performance data for each device This table was originally constructed by Ursua et al 201211
Manufacturer
Technology
(configuration)
Production
(Nm3h)
Rated Power
(kW)b
Energy
Consumption
(kWhNm3)c
Efficiency
()d
Maximum
Pressure
H2 purity
(vol)
Location
AccaGen Alkaline (monopolar) 1-100 67-487 6-487 528-727 10 999 Switzerland
Avalance Alkaline (bipolar) 04-36 2-25 543-5 652-708 448 na USA
Claind Alkaline (bipolar) 05-30 na na na 15 997 Italy
ELT Alkaline (bipolar) 3-330 138-1518 46-43 769-823 1 998-999 Germany
ELT Alkaline (bipolar) 100-760 465-3534 465-43 761-823 30 993-998 Germany
Erredue PEM (bipolar) 06-213 36-108 6-51 59-698 25-4 993-998 Italy
Giner Alkaline (bipolar) 37 20 54 655 85 na USA
Hydrogen Technologies Alkaline (bipolar) 10-500 43-2150 43 823 1 999 Norway
Hydrogenics PEM (bipolar) 10-60 54-312 54-52 655-681 10 999 Canada
Hydrogenics Alkaline (bipolar) 1 72 72 492 79 9999 Canada
H2 Logic Alkaline (bipolar) 066-4262 36-213 545-5 649-708 4 993-998 Denmark
Idroenergy Alkaline (bipolar) 04-80 3-377 75-471 472-752 18-8 995 Italy
Industrie Haute Technology Alkaline (bipolar) 110-760 5115-3534 465-43 761-823 32 998-999 Switzerland
Linde Alkaline (bipolar) 5-250 na na na 25 999 Germany
PIEL division of ILT Technology Alkaline (bipolar) 04-16 28-80 7-5 506-708 18-8 995 Italy
Proton OnSite PEM (bipolar) 0265-30 18-174 73-58 485-61 138-15 99999 USA
Sagim Alkaline (bipolar) 1-5 5-25 5 708 10 999 France
Teledyne Energy Systems Alkaline (bipolar) 28-56 na na na 10 99999 USA
Tredwell Corporation PEM (bipolar) 12-102 na na na 75 na USA
52
332 Current status review of the state of the art
This section will focus on the advancements that have recently been made in regards to SOECs Much of the
research being conducted on SOECs is focused on increasing the efficiency and stability of the electrolyte and
electrodes by changing the temperature the SOECs operate at gas mixtures and the materials the cells are
constructed from
The most common electrolyte material used in SOECs yttria-stabilised zircona (YSZ) due to it having a high
thermal stability high oxygen ion conductivity and low cost To generate YSZ zirconia (ZrO2) can be doped
with compounds such as Y2O3 and Yb2O3 to improve the stability and conductivity Sc2O3 can also be used to
generate scandia-stabilised zirconia (ScSZ) Other co-dopants such as TiO2 and Al2O3 can be added to
further enhance the stability587
Scandium stabilised zirconia (ScSZ) has a higher conductivity than YSZ but
is not as widely used due to the high costs associated with it It should also be noted that the dopant
concentration has to be of a specific amount in order to ensure the conductivity is at its maximum It has been
shown that different dopant concentrations change the lattice structure of the ZrO2 over time which leads to
the decrease in conductivity5 The dopant chosen for the SOEC is also dependent on the temperature the cell
will have to operate at as the dopant will change the conductivity of the electrolyte at different temperatures
Researchers recently investigated the effect temperature (550 oC ndash 750
oC) had on the performance of SOEC
cells with the following layout a Ni-YSZ support layer (680 microm) a Ni-ScSZ cathode-active layer (15 microm) a
ScSZ electrolyte layer (20 microm) and a LSM-ScSZ anode layer (15 microm) The performance of the cell was
observed to decrease with decreasing temperature when the same gas composition was used (143 CO
286 H2O and 571 Argon) As the temperature decreased the ionic conductivity of the electrolyte layer
decreased The mass transfer was the rate-determining step for the electrodes at temperatures lt750 oC
Methane was only detected in the gas products when the input gas composition was the same as above the
cell temperature was lt700 oC and the operating voltage was gt 2 V
81 (TRL 3)
Electrolyte materials such as ceria- and LaGaO3-based electrolytes are showing promise at intermediate
temperatures when they are doped with other compounds that increase their ionic conductivity79
Recently
researchers developed SOEC capable of steam and carbon dioxide co-electrolysis The cell was constructed
from Ni-YSZ (nickel-yttria-stabilized zirconia) solid oxide cell with a bi-layered ScSZGDC electrolyte structure
and a LSCF (lanthanum strontium cobalt ferrite) oxygen electrode When the device was operated at 800 oC
the cell exhibited a high electrolysis current density of about 22 A cm2 and 19 Acm
2 in steam and carbon
dioxide electrolysis respectively The structural integrity of the cell was checked after the experiment and no
cracking or delamination of the electrolyte or the electrolyteelectrode was observed88
(TRL 4)
Researchers were recently able to directly synthesise methane by co-electrolysing carbon dioxide and water
to form carbon monoxide and hydrogen then conducting Fischer-Tropsch synthesis in tubular solid oxide
electrolysis cells7 As previously discussed the reduction of water in SOECs requires very high temperatures
(ca 800 oC) however with the Fischer-Tropsch process lower temperatures (ca 250
oC) are required Using
the experimental setup shown in Figure 3 researchers were able to achieve a methane yield of 1184
which means that 41 of carbon dioxide is converted to methane over the course of the 24-hour test7 The
equipment consists of a SOEC tube with a hole running through its length while the wall of the tube consists
of three layers that are structured in a similar fashion to that shown in Figure 3 it consists of an anode an
electrolyte and a cathode The first section of the SOEC tube is heated to 800 oC to allow syngas to be
generated after which the tube cools over a gradient to 250 oC to allow methane production to take place
(TRL 4)
53
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis cell electrolysers This table
was originally constructed by Carmo et al 20138
Alkaline Electrolysis PEM Electrolysis SOEC Electrolysis
Advantages
Well-established technology High current densities Efficiency up to 100
Non-noble metal catalysts High voltage efficiency Efficiency gt 100
Long-term stability Good partial load range Non-noble metal catalysts
Relative low cost Rapid response system High pressure operation
Stacks in the megawatt range Compact system design
Cost effective High gas purity
Dynamic operation
Disadvantages
Low current densities High cost of components Laboratory stage
Crossover of gases Corrosive environment Bulky system design
Low partial load range Low durability Low durability
Low dynamics Stacks below megawatt range Little costing information
Corrosive electrolyte
Figure 39 A schematic diagram of co-electrolysis and the Fischer-Tropsch process being conducted in a tubular solid oxide
electrolyser that is able to produce CH4 This figure was originally generated by Chen et al 20147
333 Patents
The cell was composed of separate anode and cathode chambers separated by a membrane that allows the
transport of sodium ions (Na+) the anode and cathode chambers are in contact with water Oxygen is
collected in the anode chamber and hydrogen is collected in the cathode chamber following which hydrogen
and carbon dioxide are reacted together to generate syngas and oxygen as by-products that need to be
separated The electrode materials were described as being ceramic that could be doped with a catalyst
material such as cobalt cerium europium or cadmium combinations of these elements were also permitted89
(TRL 3)
A patent was filed in 2011 detailing a design for SOEC that could co-electrolyse steam and carbon dioxide to
produce syngas The cell consisted of a cathode composed of nickel-zirconia an anode consisting of
strontium doped lanthanum manganite and the electrolyte between the two electrodes was composed of
yttria-stabilised zirconia the whole cell was designed to operate between 800-1000 oC The authors stated
that the electrical power to run the device would be sourced from nuclear power however it should also be
possible to run this device off solar energy This device operated with the carbon dioxide being fed into the
cathode section where the hydrogen is generated90
(TRL 4)
54
A patent was filed in 2013 detailing a modified anodeelectrolyte structure for a solid oxide electrochemical
cell where the role of the anode is to react with fuel (steamhydrocarbons) The cathode (when in SOEC
mode) consisted of a backbone of electronically conductive perovskite oxides selected from the group
consisting of niobium-doped strontium titanate vanadium-doped strontium titanate and tantalum-doped
strontium titanate mixtures were also permitted The electrolyte material consisted of a scandia and yttria-
stabilised zirconium oxide91
(TRL 2-3)
334 Future development main challenges
Technologies that are capable of electrolysing water cover a variety of TRLs wherein alkaline and PEM
electrolysers used to generate hydrogen by the water-splitting reaction have TRLs 7-8 as they have been
commercialised can be purchased and can produce power at the low megawatt scale However they are
currently not a viable option to generate power at the megawatt scale Newer SOEC technologies currently
being developed have lower TRLs (3-5) but are showing great promise in that their efficiencies are high and
they are cheap to produce
Technologies capable of co-electrolysing water and carbon dioxide to syngas are at an early stage of
development - TRLs 2-4 Research is still focused on studying how cell conditions can be manipulated to
optimise the production of syngas and hydrocarbons Research is also focused on improving the long-term
stability of the electrolytes and electrodes used in SOECs by investigating new materials and cell designs that
are cheap and easy to construct It will also be necessary to conduct duration experiments In terms of their
commercial viability they are far behind PVs at roughly the same stage as PEC technologies and ahead of
synthetic biology systems
SOECs could prove to be an efficient method by which electrical energy generated from renewable sources
(wind and solar) could be stored in the form of chemical bonds To date it has been proven that syngas can
be generated from SOECs and that methane can also be generated within the same system through a
Fischer-Tropsch process More research is needed that aims to improve the efficiency by which methanol can
be generated and to determine whether more complex hydrocarbons can be synthesised
The success of this technology is likely to be dependent on how well systems that generate electricity from
renewable sources can be integrated within it It has been suggested that nuclear wind and solar power
stations could be used to provide the electrical power required This would help to lower the cost of this
technology as sourcing the electricity needed is one of the major costs It should be noted that one of the
most commonly cited advantages of this technique over solar and wind power is that it is not site-specific
However if solar and wind power were to be used to generate the electricity needed for this technology then
it becomes a site-specific technology again This is also a problem for PEC-cell-based technologies
34 Summary
The aim of this brief literature review was to highlight the advancements that have been made across the main
technologies within artificial photosynthesis discuss some of the most recent technological solutions that have
been developed in these areas and identify the main challenges that need to be addressed for each
technology before they can be commercialised
Synthetic biology amp hybrid systems
Synthetic biology amp hybrid artificial photosynthetic systems are currently capable of producing small amounts
of fuel molecules such as hydrogen and simple hydrocarbons The majority of the technologies in this
category are at the research and development stage (TRL 1-4) To date there are no large scale plans to
produce solar fuels at a commercial level using this technology It should be noted that synthetic biology amp
hybrid systems are currently used to produce fine chemicals at the commercial level but these are not needed
55
in the large quantities in which solar fuels are required It is currently too early to comment on the long-term
commercial viability of this technological pathway however the research in this area is progressing quickly
and as our fundamental understanding of biological systems increases progression is promising It should be
noted that these systems are becoming efficient enough to produce hydrogen at a rate that is comparable to
that which occurs in natural photosynthesis on a small laboratory scale
Photoelectrocatalysis of water (water splitting)
PVssemiconductors are the most advanced technology discussed in this report as they have been
commercialised and are able to generate electricity on a MW scale at facilities such as the Solar Star Power
Station and the Topaz Solar Farm31
PVssemiconductors are used in PEC technologies where they are
incorporated into the cell design and act as light absorbers Instead of the energy gained from light absorption
being used to generate electricity directly it is used to generate fuel molecules such as hydrogen from the
water-splitting reaction The hydrogen generated from this process can then be stored and used at a later time
to provide energy This is useful because PVs are only able to generate power intermittently during daylight
hours There are many examples of photoelectrocatalysis being carried out by PECs as well as suspensions
of photoactive nanoparticles and the majority of the technologies have a TRL 2-4 However it should be noted
that PVsemiconductor technologies that generate electrical power have TRL 8-9 The main challenges facing
this technology involve developing materials that have high STH efficiencies are cheap to manufacture and
are stable for long periods of time Calculations have been performed to determine the efficiencies associated
with multiple reactor plant designs These have shown that it is theoretically possible to generate large
quantities of hydrogen however that it could cost trillions to generate a significant amount of hydrogen with
current technology
Co-electrolysis
Water electrolysers such as alkaline and PEM electrolysers are considered mature technologies that have
been commercialised and have TRLs 7-8 They can be purchased and can produce power at the low
megawatt scale However they are currently not a viable option to generate power at the megawatt scale
Newer SOEC technologies that are currently being developed have lower TRLs 3-5 but are showing great
promise in that their efficiencies are high and they are cheap to produce Technologies that are capable of
generating syngas and some organic products by a Fischer-Tropsch process are in the research and
development stage (TRL 3-4) Research is currently focused on determining how SOEC conditions can be
manipulated to increase efficiency as well as identifying more stable durable and efficient compounds to
incorporate into the cell design The incorporation of SOECs into large scale solar and wind farms could prove
to be an efficient method by which electrical energy can be stored as chemical energy
The technologies discussed above show great potential in being able to convert solar energy into solar fuels
They are still in the early research phase but all technologies made significant improvements in efficiencies
lifetimes and the number of products they can produce other than hydrogen It is likely that PVs will be used to
absorb solar energy to generate electricity for SOECs or forms part of a PEC cell that generates fuel
molecules It should be noted that wind power could be used to provide the electricity needed for SOECs to
operate which would allow these systems to be used outside of desert regions Biological systems currently
look to be less suitable for producing large quantities of fuel molecules partly due to their early research stage
but may prove to be useful in generating highly complicated molecules once the understanding of protein
engineering has increased
All of these technologies seek to improve device lifetimes increase efficiency lower manufacturing costs and
increase the scope of synthetic fuels that can be produced Switching to a hydrogen economy will require
large and expensive infrastructure changes Using hydrogen to generate more complex fuel molecules will
require more research however ultimately fewer infrastructure changes
57
4 Mapping research actors
41 Main academic actors in Europe
In Europe research on AP is conducted by individual research groups or in research networks or consortia
Most of the research groups are located in Germany the Netherlands and Sweden The largest country-based
networks are also in Sweden and in the UK Most of Germanyrsquos research groups are part of the pan-European
AP network AMPEA The number of research groups has increased substantially since the 1990s when the
field became more prominent coupling with the (exponential) rise of publications in AP3
411 Main research networkscommunities
In this section we describe the main research networkscommunities on artificial photosynthesis in Europe
Under networks we indicate co-operations with multiple universities research organisations and companies
Instead of focusing strictly on major integrated research on specific AP topics the networks mostly have a
broad research and collaboration focus Larger joint programmes exist but are more focused on various key
priorities in Europe for different research areas such as AMPEA (Advanced Materials and Processes for
Energy Application) which is one of the joint programmes of EERA (European Energy Research Alliance) of
which artificial photosynthesis is one of the three identified applications The first national research network
dedicated to artificial photosynthesis was the Swedish Consortium for Artificial Photosynthesis (CAP)
following which a number of other national and pan-European networks emerged in the past few years
Research networks and communities play an important role in facilitating collaboration across borders and
among different research groups The development of AP processes needs expertise from molecular biology
biophysics and biochemistry to organometallic and physical chemistry Research networks provide the
platform for researchers and research teams from those diverse disciplines to conduct research together to
create synergistic interactions between biologists biochemists biophysicists and physical chemists all
focusing on questions relevant for AP and solar fuels This need for research coordination is reflected by the
fact that the Swedish Consortium for AP was a bottom-up initiative by university-based scientists4
Furthermore networks are effective for promoting AP research and raising public awareness and knowledge
about AP5
Networks and consortia with industrial members also play an important role with respect to the goal of turning
successfully developed AP processes into a commercially viable product Research and innovation in
materials and processes of AP can be backed up by private innovation and investments Feedback on the
applicability of research outputs can be incorporated and shape further research efforts and application
possibilities in the business sector can be discovered
The advantages and synergy effects of network membership for research groups are reflected in the fact that
more than 50 of European research groups are part of a research network in Europe The consortia vary in
their membership and their funding sizes whereas about 400 researchers are affiliated with the pan-European
consortium AMPEA the Swedish CAP unites about 80 scientists Furthermore it is apparent that only AMPEA
is a truly pan-European consortium member research groups come from various European countries such as
Austria France Czech Republic Germany Italy the Netherlands Norway Spain Sweden Switzerland and
3 V Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in
ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press) conducted a bibliometric analysis using key words related to the field of artificial photosynthesis showing that only a few papers were published before the 1990s reaching more than 900 publications in 2014
4 httpwwwsolarfuelse
5 httpsolarfuelsnetworkcomoutreach
58
the UK Most of the other consortia discussed below are based in a specific country which is reflected in their
affiliations among research groups
EU - AMPEA
The European Energy Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials
amp Processes for Energy Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging
Technologies and artificial photosynthesis became the first energy research subfield to be organised within
AMPEA The goal of this joint programme which was launched at the end of 2011 is to set up a thorough and
systematic programme of directed research which by 2020 will have advanced to a point where commercially
viable artificial photosynthetic devices will be under development in partnership with the industry Its goal to
boost research on a pan-European basis is reflected in the fact that to date more than 40 European scientific
institutions participate Many institutes in different Member States are associated with AMPEA (31 full
members for example CEA DIFFER TU Delft JKU Max Planck Institute)6 The research efforts of the
AMPEA participants aim at advancing all of the three identified pathways of artificial photosynthesis Due to
the low availability of efficient molecular catalysts based on earth-abundant elements the search for those
elements and the development of such catalysts constitute the early research focus
Italy ndash SOLAR-CHEM
In 2009 the universities of Bologna Ferrara and Messina founded SOLAR-CHEM the Italian inter-university
centre for the chemical conversion of solar energy7 Later on other universities in Italy also joined SOLAR-
CHEM The research efforts of the centre aim to foster research in solar fuels through a multidisciplinary
approach and coordination activities eg through the organisation of dedicated events and through short-term
exchanges of staff in the network
Netherlands ndash BioSolar Cells
The Dutch BioSolar Cells public-private partnership was established in 2010 BioSolar Cells is a cooperation
of 10 knowledge institutions such as Leiden University Delft University of Technology and the University
of Twente8 as well as 45 private industries
9 The programme is funded by FOMALWNWO the Dutch
ministry of Economic Affairs Agriculture and Innovation many companies and a number of Dutch universities
and research organisations The BioSolar Cells programme has three themes artificial photosynthesis
photosynthesis in cellular systems and photosynthesis in plants These three research themes are
underpinned by a fourth theme education and societal debate where educational modules are developed to
equip and inspire future researchers policy makers and industrialists and where the societal consequences
of new solar-to-fuel conversion technologies are debated10
Sweden - CAP
Founded in 1994 the Swedish Consortium for Artificial Photosynthesis carries out integrated basic
research with the goal to produce applicable outcomes such as fuel from solar energy and water Their
projects integrate two topics artificial photosynthesis in man-made systems to make hydrogen from sun and
water and photo-biological fuel production in living organisms They focus on photoelectrocatalysis as the
technology pathway yet are also building on their research on the principles of natural photosynthesis for
energy production A unique component in the consortium is hence the synergistic interactions between
biologists biochemists biophysicists and physical chemists all focusing on questions relevant for solar
fuels11
The academic partners come from Uppsala University Lund University and the KTH Royal
Institute of Technology in Stockholm
6 httpwwweera-seteueera-joint-programmes-jpsadvanced-materials-and-processes-for-energy-application-ampea
7 httpswwwsocchimitsitesdefaultfileschimindpdf2012_6_88_capdf
8 httpwwwbiosolarcellsnlover-biosolar-cellsnew_page_1html
9 httpwwwbiosolarcellsnlover-biosolar-cellsbedrijvenhtml
10 httpwwwbiosolarcellsnlonderzoek
11 httpwwwsolarfuelsesolar-fuels
59
UK ndash SolarCAP
The SolarCAP Consortium for Artificial Photosynthesis is a consortium of four UK academic research groups
funded by the Engineering and Physical Sciences Research Council The groups based in the Universities
of East Anglia Manchester Nottingham and York12
are specifically exploring the solar conversion of
carbon dioxide to carbon monoxide in tandem with the conversion of methane or alkanes to useful oxygen-
containing products such as alcohols They are exploring the second technological pathway of
photoelectrocatalysis
UK ndash Solar Fuels Network
Solar Fuels Network brings together academic and industrial researchers in solar fuels and artificial
photosynthesis It aims to develop an effective community of solar fuels researchers from both academia and
industry to raise the profile of the UK solar fuels research community nationally and internationally Through
this it aims to promote collaboration and co-operation with other research disciplines industry and
international solar fuels programmes and to contribute towards the development of a UK solar fuels
technology and policy roadmap The networkrsquos management team is based at Imperial College London and
is led by Prof James Durrant Partner organisations encompass the Royal Society of Chemistry the Energy
community of the Knowledge Transfer Network (KTN) the Solar Fuels Institute (SOFI) and the Foreign and
Commonwealth Officersquos Science and Innovation Network13
In other countries across Europe national initiatives have emerged in the last few years and more are
expected to in the future For example the Photoelectrochemistry Competence Center (PECHouse and
PECHouse2)14
under coordination of the Ecole Polytechnique Federale de Lausanne (prof Michael Graumltzel)
has been created in Switzerland while in France artificial photosynthesis is being researched by laboratories
of excellence (LabEx Arcane15
and LabEx Charmatt16
)
412 Main research groups (with link to network if any)
A list of the main research groups in Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire Artificial
Photosynthesis community Taking that into account the numbers presented below may provide an indication
of the AP research sector as a whole
Table 41 Number of research groups and research institutions in European countries
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Austria 1 1 15
Belgium 1 1 -
Czech Republic 1 1 -
Denmark 3 2 -
Finland 1 1 6
France 5 3 14
Germany 31 17 16
Ireland 1 1 7
Italy 5 5 29
Netherlands 28 9 18
Norway 1 1 -
12
httpwwwsolarcaporgukresearchgroupsasp 13
httpsolarfuelsnetworkcommembership 14
httppechouseepflchpage-32075html 15
httpswwwlabex-arcanefrencontentlaboratoires-excellence-arcane 16
httpwwwcharmmmatfrindexphp
60
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Spain 4 4 11
Sweden 13 5 17
Switzerland 5 5 10
UK 13 9 10
Total 113 65 15
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 66 main research institutions and universities working on artificial photosynthesis in Europe
Those research institutions contain 113 individual research groups with an average size of about 15
people17
The sizes of research groups can vary widely from for example 80 members of a research group at
Imperial College London to only two persons in the research group of Klaus-Dieter Weltmann at the Leibniz
Institute for Plasma Science and Technology The country with both the highest number of involved institutions
and research groups is Germany where 32 individual research groups in 17 research institutions are active
Germany is followed by the Netherlands with nine institutions and 28 research groups and by Sweden with
five institutions and 13 research groups Almost half (47) of the research groups focus on the second
pathway ie photoelectrocatalysis whereas 36 research the first pathway ie the usage of synthetic
biology and hybrid systems to produce fuel molecules and about 17 follow the third pathway in their
research which is co-electrolysis A bulk of the research in most countries is done on the second pathway
except for in Sweden and Finland which seem to specialize in exploring the first pathway Table 42 provides
an overview of some of the key statistics the number of research groups and research institutions in AP per
country and the number of research groups focusing on each of the three technological pathways
respectively
Table 42 Number of research groups per research area (technology pathway)
Country Total Synthetic biology
amp hybrid systems
Photoelectrocatalysis Co-electrolysis
Austria 1 1 1 0
Belgium 1 1 1 0
Czech Republic 1 0 1 0
Denmark 3 0 2 2
Finland 1 1 0 0
France 5 2 5 0
Germany 31 14 15 9
Ireland 1 1 1 0
Italy 5 0 5 0
Netherlands 28 12 17 9
Norway 1 0 1 0
Spain 4 2 3 1
Sweden 13 10 7 0
Switzerland 5 1 5 3
UK 13 8 5 1
Total 113 53 69 25
Source Ecorys
17
The average group size is derived from survey responses and available information on the websites of the groups
61
In the following section our findings have been illustrated by presenting some of the main research institutions
and their research groups
Germany - Helmholz Zentrum Berlin
The Institute for Solar Fuels of the HZB is led by Prof Roel van de Krol The institute pursues a strategy to generate
hydrogen via the second technology pathway they combine the energy conversion of light into electrical energy via
photonic stimulation of the semiconductor directly with the catalytic procedures on the electrolyte-electrode-interface for
the conversion into storable chemical energy (hydrogen) The generated hydrogen can then be stored by means of
already known methods (compressed gas liquid-H2 metal hydride conversion to methanol) Their approach combines
research and insights from photo-physics surface- and material chemistry photoelectrochemistry interface- and
surface sciences as well as system alignment18
Therefore they collaborate closely with the University of Messina in
Italy and the Leiden University in the Netherlands Moreover the HZB is also part of the European research network
AMPEA
Germany ndash Max Planck Institute for Chemical Energy
The Department of Biophysical Chemistry at the Max Planck Institute for Chemical Energy focus on the water-oxidizing
enzyme of oxygenic photosynthesis and hydrogenases Their research uses a variety of different physical techniques
to gain insight into enzymatic processes such as into photosynthetic water splitting and (bio)hydrogen production
which can be used for biomimetic chemistry ie to develop catalytic systems in energy research19
They hence focus
on the first and second technology pathways The Max Planck Institute for Chemical Energy also contributes to the
European research network AMPEA
The Netherlands - The Dutch Institute for Fundamental Energy Research
Part of the Netherlands Organisation for Scientific Research (NWO) the DIFFER institute has since its initiation in 2012
grown to an activity of about 65 Meuroyear (about 75 fte) all directed at the production of chemicalsfuels from electrons
and photons In particular as part of its solar fuels research DIFFER investigates the splitting of water into hydrogen
and oxygen using electricity and the reduction of carbon dioxide to carbon monoxide As they are located at TUe
campus in Eindhoven they can easily collaborate and share knowledge with universities universities of applied
sciences and industry The DIFFER institute also contributes to AMPEA
Sweden ndash Uppsala University
Various research teams at Uppsala University cover all three relevant technology pathways for artificial
photosynthesis20
Moreover in 2006 the Swedish Consortium for Artificial Photosynthesis (CAP) founded in 1994 by
three researchers from Uppsala University and one researcher from the University of Stockholm created a new
scientific environment at the Aringngstroumlm laboratory at Uppsala University becoming the base for this consortium
Switzerland ndash ETH Zurich
The Professorship of Renewable Energy Carriers21
performs RampD projects in emerging fields of renewable energy
engineering operates state-of-the-art experimental laboratories offers advanced courses in fundamentalapplied
thermal sciences and produces qualified scientists and engineers with expertise in renewable energy technologies
Regarding solar fuels they focus on solar splitting of H2O and CO2 via thermochemical Redox cycles which
corresponds to the third technology pathway of artificial photosynthesis They are partners in several EU projects
concerning solar-driven hydrogen production such as SOLARJET ndash Solar Production of Jet Fuel from H2O and CO2
and HYCYCLES ndash Solar Water-Splitting Thermochemical Cycle22
18
httpswwwhelmholtz-berlindeforschungoeeesolare-brennstoffeindex_enhtml 19
httpwwwcecmpgderesearchbiophysical-chemistryoverviewhtmlL=1 20
httpwwwkemiuuseresearchmolecular-biomimeticphotosynthesis 21
httpwwwprecethzch 22
httpwwwprecethzchresearchsolar-fuelshtml
62
UK ndash Imperial College London
The research of various research teams of the Imperial College London encompasses the first and second technology
pathways It ranges from research on the oxidising enzyme Photosystem II which has become the focus of attention
because cheap water-splitting catalysts are urgently needed in the energy sector to the development of
photoelectrodes and nanoparticles for solar-driven fuel synthesis based on water splitting of water into hydrogen and
oxygen Collaborations across the Imperial College London are complemented with co-operations across the UK as
part of the UK Solar Fuels Network with the Swiss Federal Institute of Technology in Lausanne (EPFL) UCL and
Cambridge University
The density of research group per country in Europe is presented schematically in Figure 41
Figure 41 Research groups in Artificial Photosynthesis in Europe
Source Ecorys
42 Main academic actors outside Europe
Also outside of Europe research on AP is conducted by individual research groups or in research networks or
consortia Most of the research groups and networks are located in the US and in Japan Whereas US-based
networks sporadically have ties to European research groups the Japanese consortia have exclusively
Japanese members both academic and industrial
421 Main research networkscommunities
Outside of Europe the main networks can be found in the US and in Japan The biggest network is the US
network JCAP (Joint Center for Artificial Photosynthesis) with more than 190 persons linked to the
programme and a budget of $122 million for five years Next in line is the Japanese ARPChem which has
roughly the same budget available for a time span of 10 years
63
Japan ndash ARPChem
The Japanese Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology jointly launched the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem) in November 2012 The aim is to bundle efforts for the next
decade to develop innovative catalysts and other materials that could be used for manufacturing fundamental
chemical substances from water and carbon dioxide by making use of solar power Such substances can be
used as raw materials of plastics synthetic fibres synthetic rubber solvents and other products and are
applicable in all areas of peoples everyday lives The expected budget for the coming decade between 2012
and 2021 amounts to 15 billion yen (euro 122 million)23
The utilisation of catalyst technology requires long-term
involvement and entails high risks in development but is expected to have a huge impact on Japans
economy and society The aim is to achieve independence from fossil resources used as raw materials for
chemical substances while overcoming resource and environmental challenges The consortium consists of
partners from academia industry and the government seven universities amongst them the University of
Tokyo the Tokyo University of Science and the Kyoto University companies such as Mitsubishi
Chemicals Mitsui Chemicals Fuji Films and TOTO and governmental research organizations such as the
National Institute of Advanced Industrial Science and Technology (AIST)
Japan ndash All Nippon Artificial Photosynthesis Project for Living Earth (AnApple)
The All Nippon Artificial Photosynthesis Project for Living Earth (AnApple) is one of the Scientific
Researches on Innovative Areas receiving strong financial support from the Ministry of Education Culture
Sports Science and Technology It was set up in 2012 as a five-year national project Although it is not a
consortium in a narrow sense its scope and research impact are substantial as more than 40 Japanese
leading scientific groups are part of this project It is led by Prof Haruo Inoue from the Tokyo Metropolitan
University further academic partners are amongst others the Tokyo University of Science the Tokyo
Institute of Technology Ibaraki University Ritsumeikan University and Hokkaido University
South Korea ndash KCAP
The Korean Centre for Artificial Photosynthesis (KCAP) was launched at Sogang University in 200924
set up
as a ten-year programme with 50 billion won (about euro40 million)25
It aims to secure a wide range of
fundamental knowledge necessary materials and device fabrication for the implementation of artificial
photosynthesis ie generating liquid fuel and oxygen from water and carbon dioxide using solar energy
through collaborative research with a number of research organisations and companies The Korean partners
comprise 14 professors from 8 universities including Sogang University Yonsei University and the Ulsan
National Institute of Science and Technology and one industry partner Pohang Steel Company26
Foreign academic partners are the Lawrence Berkeley National Laboratory California Institute of
Technology and University of California Berkeley The Centre has ties to other AP networks such as SOFI
and JCAP
US ndash JCAP
In 2010 the Department of Energy created the Energy Innovation Hubs and among them a Joint Centre for
Artificial Photosynthesis (JCAP) was established between the California Institute of Technology and the
Lawrence Berkeley National Laboratory in California27
JCAP draws on the expertise and capabilities of key
collaborators from the University of California (UCI and UCSD) and the SLAC National Accelerator Laboratory
operated by Stanford University The initial funds in 2010 amounted to $122 million JCAP is the largest
artificial photosynthesis network in the US with more than 190 persons linked to the programme The research
foci encompass electro-catalysis photo-catalysis and light capture materials integration and numerical
23
httpwwwmetigojpenglishpress20121128_02html 24
httpwwwk-caporkrenginfoindexhtmlsidx=1 25
httpwwwsogangackrnewsletternews2011_eng_1news12html 26
httpswwwicef-forumorgannual_2015speakersoctober8cs2appdfcs-2_20058_kyung_byung_yoonpdf 27
httpsolarfuelshuborgwho-we-areoverview
64
modelling test-bed prototyping and benchmarking The funds for the next five-year period (2016-2020)
amount to $75 million and are subject to congressional appropriation
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years Core members include the Northwestern University and
Uppsala University A process of exchanges is instituted which encompasses six different universities in four
countries Industry partners are ILampFS (India) Total (France) and Shell28
This list is not exhaustive and increasing interest in the field of artificial photosynthesis would certainly lead to
the launch of new national and international programmes
422 Main research groups (with link to network if any)
A list of the main research groups outside Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire AP
community outside of Europe We are confident however that it provides an accurate indication about the AP
sector outside of Europe
Table 43 Number of research groups and research institutions in non-European countries
Country Number of research groups Number of research institutions Average size of a
research group
Australia 1 1 18
Brazil 1 1 5
Canada 1 1 -
China 12 5 13
Israel 1 1 6
Japan 16 15 15
Korea 4 4 16
Singapore 1 1 14
US 40 32 18
Total 77 61 5
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 61 main research institutions or universities working on artificial photosynthesis outside of
Europe most of which are based in the US and in Japan Those research institutions contain 77 individual
research groups with an average group size of 8 people29
Yet the sizes of research groups can vary widely
from 26 members at the University of Tokyo to only two persons at Kobe University The country with both the
highest number of involved institutions and research groups is the US where 40 individual research groups in
32 research institutions are active Hence the US is a world leader in terms of research groups working on
AP Japan follows with 16 institutions and 15 research groups which lies below the numbers for Germany
and the Netherlands Almost 80 of the research groups (77) focus on the second pathway
(photoelectrocatalysis) whereas about 39 research the first pathway (synthetic biology amp hybrid
systems) The remaining 18 focus their activities on the third pathway (co-electrolysis) Table 44
28
httpwwwsolar-fuelsorgabout-sofi 29
The average group size is derived from survey responses For more information please refer to Annex I
65
provides an overview of some of the key statistics such as the number of AP research groups and institutions
per country and their respective focus on one of the three technology pathways
Table 44 Number of research groups per research area (technology pathway)
Country Technology
pathway
Total Synthetic biology
and hybrid systems
Photoelectrocatalysis Co-electrolysis
Australia 1 1 1 0
Brazil 1 0 1 0
Canada 1 0 1 1
China 12 4 6 2
Israel 1 1 0 1
Japan 16 7 15 1
Korea 4 0 4 0
Singapore 1 0 1 0
US 40 17 30 9
Total 77 30 59 14
Note a research group might focus on multiple technology pathways
Source Ecorys
In the following section our findings are illustrated by presenting some of the main research institutions and
their research groups
China ndash Dalian University of Technology
In 2011 the Dalian National Laboratory for Clean Energy (DNL) based at the Dalian Institute of Chemical Physics
(DICP) of the Chinese Academy of Sciences (CAS) was established It integrates research into clean energy and the
efficient use of fossil fuels to meet Chinas sustainable energy development strategy It is led by Li Can
Israel - Weizmann Institute of Science
To meet the challenge of providing clean sustainable energy the Weizmann Institute has established the Alternative
Sustainable Energy Initiative (AERI) The goal of this initiative is to create the conditions conducive to alternative
energy research and to identify promising avenues of research With the help of AERI the Weizmann institute hopes to
encourage its scientists to conduct basic research relevant to the future development of alternative sustainable energy
and to nourish the next generation of scientists in this field around the world in Israel and at the Weizmann Institute
The researchers at the Weizmann Institute of Science and at AERI preliminarily focus on the third pathway
Japan ndash University of Tokyo
The Domen Laboratory at the University of Tokyo is a research group focused on the second technological pathway
Their challenge is to find out novel photocatalysts that effectively work on water splitting under visible light by studying
different new materials
US ndash Arizona State University
The multidisciplinary team of the Center for Bio-inspired Solar Fuel Production of the Arizona State University aims to
design a complete system for solar water oxidation and hydrogen production Therefore they are focusing on five
specific subtasks (i) The total system analysis of the solar water-splitting device (ii) water oxidation (iii) fuel
production (iv) the artificial reaction center-antenna which relates to light collection and (v) the development of
functional nanostructured transparent electrode materials Their focus lies hence on the first and second AP technology
pathways
The density of research groups per country in the world is presented schematically in Figure 42 Please note
that in this figure (as opposed to Figure 41) we do not count each European country individually but
aggregate the numbers for all of Europe
66
Figure 42 Research groups active in the field of AP globally
Source Ecorys
43 Level of investment
In this section the level of investment is discussed in further detail The level of research investment in the EU
is based on the total budget of the projects whenever available In addition information is given on the time
period of the research projects
Information on the investment related to or funding of artificial photosynthesis research programmes and
projects at the national level is generally difficult to find especially for academic research groups Most budget
numbers found relate to the budget of the institution andor the (research) organisation in general and are not
linked to specific artificial photosynthesis programmes in particular unless the institute or research
programme is completely focused on artificial photosynthesis
Table 45 presents an overview of the investments made by a number of organisations
Table 45 Investments in the field of artificial photosynthesis
Country Organisation Budget size Period
Research investments in Europe
EU European Commission (FP7 and previous
funding programmes) euro 30 million 2005 - 2020
France CEA euro 43 billion 2014 covers not only AP
Germany
German Aerospace Centre (DLR) and the
Helmholtz Zentrum euro 4 billion
Annual budget covers
not only AP
Germany
Max Planck Institute for Chemical Energy
Conversion euro 17 billion 2015 covers not only AP
Germany
BMBF ldquoThe Next Generation of
Biotechnological Processesrdquo euro 42 million 2010 - present
Germany Government of Bavaria euro 50 million
2012-2016 covers not
only AP
Members of AMPEA AMPEA (EERA) euro 60 million 2010 - present
Netherlands Biosolar Cells euro 42 million 2010-present
Sweden Consortium for Artificial Photosynthesis euro 118 million 2013
UK SolarCAP and other initiatives in UK euro 92 million 2008-2013
67
Country Organisation Budget size Period
UK
University of East Anglia Cambridge and
Leeds euro 1 million 2013
Research investments outside Europe
China Dalian National Laboratory for Clean Energy euro 40 million Annual budget since
2011
Israel AERI euro 13 million 2014-2017
Japan ARPChem euro 122 million 2012 - 2021
Korea KCAP euro 385 million 2009 - 2019
UK US Plug-and-play photosynthesis euro 44 million 2014 - 2017
US JCAP euro 175 million 2010 - 2020
US SOFI euro 1 billion 2012 - 2022
Source Ecorys
431 Research investments in Europe
In Europe national researchers research groups and consortia are generally funded by European funds (such
as the ERC Grant from the European Commission) national governments businesses and universities In this
section special attention is paid to the EU FP7 projects These projects are mainly funded by European
contributions Further information is provided on AMPEA BioSolar Cells CAP SolarCap and some other AP
initiatives
Investments range between euro10 million for the national consortia (UK - SolarCap and Sweden - CAP) and euro42
million for the Dutch consortium to smaller budgets for local projects The projects at the European level are
more extensive The funds for all twenty FP7 projects related to artificial photosynthesis amount to a total
value of euro30 million AMPEA consists of around 400 professionals and an investment of approximately euro60
million contributed by the participants and associates themselves
Funding of AP research programmes and research consortia
EU ndash FP6 and FP7 projects
The FP6 and FP7 projects (6th
and 7th Framework Programmes for Research and Technological
Development) were undertaken in seven years between 2002 and 2013 and had a total budget of over euro60
billion30
Within FP7 around two thirds of the overall budget was aimed for the Cooperation programme of
which energy is one of the ten key thematic areas Investment in energy research under EU FP7 has been
around euro25 billion Various projects on artificial photosynthesis solar-powered hydrogen production by means
of water splitting have been completed under the EUrsquos Seventh Framework Programme Projects include
inter alia Solhydromics Solar-H Directfuel and H20Split FP7 is the key tool to respond to Europersquos needs in
terms of jobs and competitiveness and to maintain leadership in the global knowledge economy31
The
successor programme of FP7 has a number of projects in the field of artificial photosynthesis For example
PECDEMO project32
aims to develop a hybrid photoelectrochemical-photovoltaic tandem device with a solar-
to-hydrogen efficiency of 8-10 This illustrates the trend to move from fundamental research of materials and
processes (that was the main focus in FP6 and FP7 programmes) to the development of prototypes to reach
higher TRL levels (that is the main focus in H2020 programme)
An overview of the EU FP6 and FP7 projects on AP is presented in the table below
30
httpseceuropaeuresearchfp6pdffp6-in-brief_enpdf httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 31
httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 32
httppecdemoepflchpage-113311-enhtml
68
Table 46 EU FP6 and FP7 projects on artificial photosynthesis
EU FP7 project Technology pathway Total budget EU contribution to
the total budget
Time
period
(months)
ARTIPHYCTION Photolectrocatalysis (Water Splitting ) euro 3594581 euro 2187040 36
DIRECTFUEL Synthetic Biology amp Hybrid Systems euro 4977781 euro 3729519 48
CO2PHOTORED Photolectrocatalysis (Water Splitting ) euro 176053 euro 176053 24
COFLeaf Photolectrocatalysis (Water Splitting ) euro 1497125 euro 1497125 60
EWOCS Photolectrocatalysis (Water Splitting ) euro 168896 euro 168896 24
FAST MOLECULAR
WOCS
Photolectrocatalysis (Water Splitting )
euro 100000 euro 100000 48
H2OSPLIT Photolectrocatalysis (Water Splitting ) euro 100000 euro 100000 48
HJSC Research for fundamental understanding euro 337094 euro 337094 36
NANO-PHOTO-
CHROME
Synthetic Biology amp Hybrid Systems euro 218731
euro 218731 17
HyMap Photolectrocatalysis (Water Splitting ) euro 2506738 euro 2506738 60
PCAP Photolectrocatalysis (Water Splitting ) euro 190800 euro 190800 36
PHOTOCATH2ODE Photolectrocatalysis (Water Splitting ) euro 1500000 euro 1500000 60
PHOTOCO2 Photolectrocatalysis (Water Splitting ) euro 50000 euro 50000 24
PS3 Synthetic Biology amp Hybrid Systems euro 1997944 euro 1997944 60
SOLAR-H Synthetic Biology amp Hybrid Systems euro 2316000 euro 1800000 36
SOLAR-JET Photolectrocatalysis (Water Splitting ) euro 3123950 euro 2173548 48
SOLHYDROMICS Synthetic Biology amp Hybrid Systems euro 3655828 euro 2779679 42
SUSNANO Catalysts can be either used for hybrid
systems or the water splitting category euro 100000
euro 10000 54
TRIPLESOLAR Photolectrocatalysis (Water Splitting ) euro 2493585 euro 2493585 60
light2hydrogen Photolectrocatalysis (Water Splitting ) euro 900000
Total euro 30005106 euro 24016752 821
Source FP7 Project list
In total euro30 million of which 80 were based on European contributions have been spent on 20 projects
related to artificial photosynthesis Most projects were completely funded by the European Union On average
the time period of these projects was around 43 months the shortest project lasting only 17 months and the
longest one 60 months Almost all funding related to the topics of photoelectrocatalysis (55) and synthetic
biology amp hybrid systems (44) Some additional funding was spent on research for fundamental
understanding (the HJSC project) and catalysts which are useful for either hybrid systems or water splitting
(the SUSNANO project)
Table 47 Total EU budget on artificial photosynthesis per technology pathway
Technology pathway TRL Total budget
Synthetic biology amp hybrid systems 1-2 euro 13166284
Photoelectrocatalysis (water splitting ) 1-4 euro 16401728
Catalysts that can be used for both categories above 1-4 euro 100000
Research for fundamental understanding - euro 337094
Total - euro 30005106
69
Based on the monthly funding of the FP7 projects33
it may be observed that annual investments in artificial
photosynthesis have been increasing over the years (Figure 43) There were no projects on artificial
photosynthesis in 2008 therefore no investments were made The highest investment was made in 2014 with
euro45 million spent on projects After that investments have been decreasing It is however expected that
from 2016 more projects on artificial photosynthesis will be conducted therefore investment will rise
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020
Note It is assumed that the funding of the projects is evenly distributed over months Thus annual expenditures are
calculated as a sum of the monthly expenditures Project lsquolight2hydrogenrsquo is excluded from the calculation since there is no
information available on the number of months the project is running
Source Ecorys
EU ndash AMPEA (EERA)
EERA is an alliance of leading organisations in the field of energy research comprising more than 150
participating organisations all over Europe The primary focus of EERA is to accelerate the development of
energy technologies to the point that they can be embedded in industry-driven research Activities of EERA
are based on the alignment of own resources while over time the Joint Programmes can be expanded with
additional sources including from Community programmes34
In EERA approximately 3000 FTE (equivalent
of 3000 professionals) are involved which makes for a budget of around euro450 million35
AMPEA is one of the
programmes under EERA focusing on AP in which roughly 400 professionals are involved This would then
make for an investment of approximately euro60 million for AMPEA
The Netherlands ndash BioSolar Cells
The total budget of BioSolar Cells is around euro42 million based on public and private funds The Ministry
contributed euro25 million the NWO (The Dutch organisation on Scientific Research) euro35 million and Dutch
universities and research centres around euro7 million Private organisations invested euro65 million The specific
research programme Towards Biosolar Cells in which the Delft University of Technology is involved is
being allocated a budget of euro25 million by the Dutch Ministry of Agriculture Nature and Food Quality A
benefit of funding partly by private funding is the focus on building infrastructure and retaining key
33
It is assumed that funding is spread evenly over the months that the project is being implemented This means that if a project is running 36 months with a total budget of euro1 million it is assumed that monthly investments are euro83000 (1 million 12) If a project started in May 2010 then investment over the whole year 2010 is calculated as 8euro83000 After annual investment is calculated for all projects yearly total investment is calculated as a sum across projects
34 httpssetiseceuropaeuimplementationtechnology-roadmapeuropean-energy-research-alliance-eera
35 httpwwwapreitmedia168877busuoli_eneapdf
70
researchers Public funding of artificial photosynthesis is mostly for the short term facilitating the entry of new
groups36
Swedish ndash CAP
The Swedish Consortium for Artificial Photosynthesis connecting the universities of Lund Stockholm and
Uppsala is chaired by Stenbjoumlrn Styring There are 80 persons linked to the consortium In 2013 the Swedish
Energy Agency distributed the amount of euro118 million (SEK 108 million) in total to lsquosome of Swedenrsquos best
research groupsrsquo Out of this amount euro87 million went to three research groups at Uppsala University euro37
million to research on artificial photosynthesis to generate solar fuels euro32 million for research on dye-
sensitised solar cells and euro18 million to research on thin film solar cells (TFSC) It is the largest one-time
investment in solar energy ever in Sweden37
The Swedish Consortium for Artificial Photosynthesis ndash Stenbjoumlrn Styring
The project Molecular Solar Energy Sciences is funded by the KampA Wallenberg Foundation with euro5 million The main
research activities related to artificial photosynthesis include mechanistic studies on synthetic molecular and
moleculesemiconductor systems for the light-driven reduction of protons and CO2 and oxidation of water Furthermore
research is conducted on cyanobacteria systems for photo-biological fuel generation synthetic biology molecular
biology and metabolic engineering A second project on artificial photosynthesis is funded by the Swedish Energy
Agency (euro4 million) An additional four projects are funded by Swedish and European sources with a total of euro5
million38
UK ndash SolarCAP and others
The Engineering and Physical Sciences Research Council (EPSRC) in the UK supports several AP-related
projects through the Towards a Sustainable Energy Economy programme39
The total amount of funding is
approximately euro92 million
New and Renewable Solar Routes to Hydrogen is led by Imperial College London and is targeting both
artificial and natural photosynthetic routes to solar-derived hydrogen (euro5 million)40
Artificial Photosynthesis Solar Fuels is led by the University of Glasgow (euro2 million)41
The SolarCAP consortium for Artificial Photosynthesis is a consortium of five UK academic research
groups (based at the Universities of East Anglia Manchester Nottingham and York) they are working to
develop solar nanocells for the production of carbon-based solar fuels (euro22 million)
Funding of other AP initiativesprojects
Germany ndash German Aerospace Centre (DLR) and the Helmholtz Zentrum
The Helmholtz Zentrum is Germanyrsquos largest scientific organisation with more than 38000 employees and an
annual budget of more than euro4 billion42
It consists of 18 scientific technical biological and medical research
centres The research institutes of the German Aerospace Centre (DLR) are affiliated with the Helmholtz
Zentrum One of the Institutes of DLR the Institute of Solar Research forms part of the Helmholtz Zentrum
programme for renewable energies This programme focuses on projects on cost reduction in solar thermal
power plants the thermo-chemical generation of solar fuels in the period 2015-2019 the solar tower in Juumllich
the bioliq pilot plant and the Gross Schoumlnebeck geothermal research platform43
Research institutes submit
their research projects for evaluation by an international panel in order to qualify for funding under the
Renewable Energies Programme based on the outcome the Helmholtz Zentrum makes funding
recommendations for a five-year period
36
httpbiomassmagazinecomarticles2883towards-biosolar-cells-program-receives-government-funding 37
httpwwwuuseennewsnews-documentid=2282amptyp=artikelamparea=2amplang=en 38
Information is based on the survey responds 39
httpwwwrscorgglobalassets04-campaigning-outreachrealising-potential-of-scientistsresearch-policyglobal-challengessolar-fuels-2012pdf
40 httpgowepsrcacukNGBOViewGrantaspxGrantRef=EPF00270X1
41 httpgtrrcukacukprojectsref=EPF0478511
42 httpwwwdlrdesfendesktopdefaultaspxtabid-888515347_read-37692
43 httpwwwhelmholtzdeno_cacheenresearchenergyrenewable_energies
71
Germany ndash The Max Planck Institute for Chemical Energy Conversion (MPI CEC)
The MPI CEC was founded in 2012 to focus on the issue of energy conversion Its researchers analyse the
basic processes of energy storage and conversion within three research departments which encompass 200
employees44
The MPI CEC is for the most part financed by public funds from both the German state and
regions The MPI CEC is part of the Max Planck Society for the Advancement of Science which is a formally
independent non-governmental and non-profit association of German research institutes The budget of the
entire society amounted to euro17 billion in 2015
Germany ndash Federal Ministry of Education and Research (BMBF)
In 2010 the BMBF launched the initiative ldquoThe Next Generation of Biotechnological Processesrdquo45
Part of this
initiative were deliberations directed toward simulating biological processes for material and energy
transformation A funding amounting euro42 million is available for the first 35 projects on microbial fuel cells
artificial photosynthesis and universal production46
Germany ndash SolTech (Solar Technologies Go Hybrid)
The Government of Bavaria initiated SolTech an interdisciplinary project to explore innovative concepts for
converting solar energy into electricity and non-fossil fuels The project brings together research by chemists
and physicists at five different Bavarian Universities and is funded with euro50 million for the period 2012-201647
The SolTech network covers all fields of research on solar energy use such as the conversion of solar energy
to electricity for immediate use and the conversion of solar energy into chemical energy for storage and future
use
France - Alternative Energies and Atomic Energy Commission (CEA)48
CEA is a public government-funded research organisation active in four main areas low-carbon energies
defence and security information technologies and health technologies The CEA is the French Alternative
Energies and Atomic Energy Commission The CEA had a total budget of euro43 billion and around 16000
permanent staff On photovoltaic cell technology CEA is collaborating with Photowatt Pechiney and Appolon
Solar and on photovoltaic modules and systems with TOTAL Energie
UK - University of East Anglia (UEA) Cambridge and Leeds
A specific research programme by the UEA on the creation of hydrogen with energy derived from
photocatalysts designed to replicate photosynthesis is funded by the Biotechnology amp Biological Sciences
Research Council (BBSRC) The total amount of funding is approximately euro1 million (pound800000)49
432 Research investments outside Europe
The main research programmes and consortia discussed are JCAP (US) SOFI (US) ARPChem (Japan)
AnApple (Japan) and KCAP (Korea) In contrast to Europe the use of energy innovation hubs ie major
integrated research centres drawing together researchers from multiple institutions and varied technical
backgrounds is more common in the US and Asia Also partnerships between the government academia
and industry seem to be more common in those areas than they are in Europe The idea of developing new
energy technologies in innovation hubs is very different compared to the approach of helping companies scale
up manufacturing through grants or loan guarantees50
The information on the budgets from the large
networks is generally available
44
httpwwwcecmpgdeinstitutdaten-faktenhtml 45
httpswwwbiotechnologiedeBIONavigationENrootdid=164934htmlview=renderPrint 46
httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf 47
httpwwwsoltech-go-hybriddeabout-soltech 48
httpenglishceafrenglish-portal 49
httpwwwwiredcouknewsarchive2013-0122artificial-photosynthesis 50
httpswwwtechnologyreviewcoms429681artificial-photosynthesis-effort-takes-root
72
Funding of AP research programmes and research consortia
Japan ndash ARPChem
In Japan the Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology (MEXT) launched a large artificial photosynthesis project that will tackle the study for
the coming decade between 2012 and 2021 with an expected budget of about euro122 million (15 billion yen)
The main organisation to conduct the project is the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem)51
Japan ndash AnApple
All Nippon Artificial photosynthesis Project for Living Earth (AnApple) is a five-year research programme
(2012-2017) joined by more than 40 Japanese leading scientific groups In this strong collaboration they aim
at achieving breakthroughs for the realisation of artificial photosynthesis AnApple hosted The International
Conference on Artificial Photosynthesis (ICARP)rdquo in 2014 and receives strong financial support52
from the
Ministry of Education Culture Sports Science and Technology
Korea ndash KCAP
The Korea Center for Artificial Photosynthesis (KCAP) at Sogang University was established in September
2009 through complementary and collaborative research with the Lawrence Berkeley National Lab (LBNL) in
the US to build the foundation for the realisation and commercialisation of artificial photosynthesis KCAP
receives a grant of euro385 million (50 billion won in 10 years) from the Ministry of Education Science and
Technology (MEST) through the National Research Foundation of Korea (NRF)
US - JCAP
JCAP (Joint Centre for Artificial Photosynthesis) was established in 2010 by the Department of Energy as one
of the Energy Innovation Hubs with a fund of euro108 million ($122 million) for five years Additional funding for
the next five years amounts to euro67 million ($75M) but is still subject to congressional appropriation53
JCAP
is the largest artificial photosynthesis research programme in the world There are 190 persons linked to the
research programme
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years SOFI (Solar Fuels Institute) is focused on light capture
water splitting CO2 catalysis and photoelectrochemical cells SOFI relies on a community of member
institutions and individual supporters who believe strongly in a clean energy future54
The solar fuel created
using catalysts and technology shared by global members of SOFI is funded by crowdfunding campaigns
(Kickstarter campaign) Furthermore SOFI partnered with TSRC to raise by means of a bold campaign one
billion dollars over the next ten years to fund the research55
Funding of other AP initiativesprojects
US ndash Plug-and-play photosynthesis CAPP (combining algal and plant photosynthesis)
Three UKUS-funded projects received funding to improve photosynthesis The three research teams (each
comprised of scientists from the United Kingdom and the United States) have been awarded a second round
of funding to build on their research findings and develop new ways to improve photosynthesis Projects
include plug-and-play photosynthesis by the Arizona State University Multi-level Approaches for Generating
Carbon Dioxide (MAGIC) led by the Pennsylvania State University and Combining Algal and Plant
Photosynthesis (CAPP) led by the Stanford University received in 2014 a new round of funding of euro44 million
51
httpwwwmetigojpenglishpress20121128_02html 52
httpartificial-photosynthesisnetICARP2014scopehtml The concrete funding figures are not available 53
httpenergygovarticlesenergy-department-provide-75-million-fuels-sunlight-hub) httpsolarfuelshuborgresearchoverview 54
httpwwwsolar-fuelsorgdonate 55
httpstelluridescienceorgsofi-brochurepdf
73
(pound5 million) in total over three years from the Biotechnology and Biological Sciences Research Council
(BBSRC) and the National Science Foundation56
Israel ndash Projects funded by AERI
AERI is providing a pool of funds to try out new ideas and jump-start research projects that are not applicable
for conventional grants Since 2006 already 8 cycles of AERI-funded projects took place Projects under the
20132014 cycle include lsquoNew Options for Solar Energy Conversion to Biofuel and Electricity ndash Biofuels ndash
Photovoltaics and Opticsrsquo57
Funding is provided by the Canadian Center for Alternative Energy Research the
Helmsley Energy Program the Helmsley Charitable Trust (providing euro13 million ($15 million) over three
years) the Burk Fund for Alterative Energy Studies the Eisenberg Foundation and individuals58
China ndash Funding of the Dalian National Laboratory for Clean Energy
The Dalian National Laboratory for Clean Energy was established in 2011 The investments into this lab
amount to more than euro40 million (289 million RMB) a year (over 50 of annual research of the Dalian
University of Technology within which the laboratory functions)59
In addition to this laboratory Haldor Topsoe
opened an RampD Center60
at the same university to join forces in the research of clean energy Haldor Topsoe
is also going to sponsor RampD projects however the size of the investments is not revealed Prior to that
Topsoe already established a scholarship with a value of around euro400 a month (3000 RMB)61
44 Strengths and weaknesses
This section presents the analysis of the strengths and weaknesses of the research community in the field of
artificial photosynthesis The findings are based on the results of the survey conducted during March 2016
and are supplemented by desk research Firstly we outline the main strengths and weaknesses with regard to
global AP research Secondly the strengths and weaknesses of the European community compared to the
non-European community are presented
441 Strengths and weaknesses of AP research in general
Table 48 below summarises the strengths and weaknesses of research in AP taking a global perspective
Table 48 Summary of strengths and weaknesses of research globally
Strengths Weaknesses
A diverse community of researchers bringing together
experts in chemistry photochemistry electrochemistry
physics biology catalysis etc
Researchers focus on all technology pathways in AP
Existing research programmes and roadmaps in AP
Available financial investments in several countries
Limited communication cooperation and collaboration
at an international level
Limited collaboration between academia and industry
at an international level
Transfer from research to practical applications is
challenging
Note International level refers not only to EU countries but all around the world
Globally there is a wide variety of RampD institutes (and researchers) focused on AP forming a diverse
community of researchers Research in AP requires interdisciplinary teams The experts working together
on this topic often have backgrounds in chemistry physics and biology
56
httpwwwbbsrcacuknewsfood-security2014140602-pr-bbsrc-and-nsf-funding-photosynthesis 57
httpwwwweizmannacilAERIresearch 58
httpwwwweizmannacilresdevsitesweizmannacilresdevfilesenergy_booklet_lo_res_2012pdf 59
httpwwwnaturecomnews2011111031fullnews2011622html 60
httpwwwtopsoecomnews201602topsoe-establishes-rd-center-dalian-institute-chemical-physics-china 61
httpwwwdnlorgcnshow_enphpid=776
74
A diverse community of researchers is focusing on all the pathways in AP which ensures diverse
approaches an exchange of different views a dynamic research community and avoids lock-ins into one
specific pathway This broad and inclusive research approach is the best way to maximise the probability of
AP research being successful in developing efficient and commercially viable AP processes
Several countries have dedicated programmes andor roadmaps to the topic of AP The US Japan the
Netherlands and South Korea have invested in large-scale interdisciplinary research programmes (specifically
on solar fuels) China and Japan have dedicated centres for renewable energy research where solar fuels are
an area of substantial effort For example the Department of Energy of the US sponsors Energy Innovation
Hubs aiming to overcome scientific barriers to develop a complete energy system with the potential to turn into
a transformative energy technology62
One of such innovation hubs is the Joint Center for Artificial
Photosynthesis established in 2010 In the Netherlands a public private partnership was established to form
BioSolar Cells of which one of the main focal themes is AP Globally several hundreds of millions of euros
are being spent this decade on AP research and this research seems to be intensified further
Despite the intensification of global research efforts the communication cooperation and collaboration at
an international level remains limited Many AP consortia link different research groups but operate only at
a national level63
Yet a higher level of institutionalised international or global cooperation going beyond
international academic conferences could spur innovative research in the field and enhance knowledge
exchange and spill-overs A number of survey respondents indicated that the lack of coordination
communication and cooperation at an international level is one of the main weaknesses in current AP-related
research activities
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research
including research on artificial photosynthesis In Japan the industry is involved in AP research to a greater
degree64
Nevertheless although companies are participating in local consortia such as ARPChem and
BioSolar Cells there seems to be a lack of cooperation between academia and industry at an
international level
The transfer of research to industrial application in artificial photosynthesis remains challenging In order
to attract the attention of the private sector artificial photosynthetic systems must be cost-effective efficient
and durable An active involvement of industrial parties could help bringing research prototypes to
commercialisation This step towards commercialisation requires a sufficient critical mass and funding
however which cannot be borne by a single country
442 Strengths and weaknesses of AP research in Europe
Table 49 below summarises the strengths and weaknesses of research in artificial photosynthesis in Europe
as compared to non-European research
62
httpscienceenergygovbesresearchdoe-energy-innovation-hubs 63
The only exception is AMPEA with its pan-European reach 64
The Korean Centre for Artificial Photosynthesis (KCAP) collaborates with a number of companies Toshiba and Panasonic made some advances in artificial photosynthesis research (httpasianikkeicomTech-ScienceScienceHow-artificial-photosynthesis-could-cut-emissions) ARPChem has a few corporate members on board (httpwwwmetigojpenglishpress2012pdf1128_02bpdf)
75
Table 49 Summary of strengths and weaknesses of research in Europe
Strengths Weaknesses
A strong diverse community of researchers
RampD institutions research capacity and facilities
Existing research programmes and roadmaps for AP in
several MS
Available financial investments in MS
Ongoing and conducted FP7 projects at EU level
Close collaboration of research groups in consortia
Limited communication cooperation and collaboration at
a pan-European level
Limited collaboration between academia and industry
within Europe
Limited funding mostly provided for short-term projects
focusing on short-run returns
National RampD efforts in AP are scattered
Europe has a diverse research community working on artificial photosynthesis research covering all the
technology pathways Europersquos universities have many highly educated researchers in the fields of chemistry
physics and biology at their disposal There is a solid foundation of RampD institutions research capacity
and facilities such as specialised laboratories which work together at a national level
National research programmes and roadmaps for AP exist in several Member States an indication that
AP research is on the agenda of European governments65
Therefore also financial investment for AP
research is available in several MS such as in Germany66
and other countries European-level
collaboration between different research groups and institutes from different countries has been achieved in
the framework of FP7 projects67
as well as predecessors of it
Five main consortia in Europe ensure that research groups and research institutes are collaborating
closely68
such as in Sweden where the Consortium for Artificial Photosynthesis (CAP) is active and in the
Netherlands where researchers work in close cooperation within the BioSolar Cells consortium Nevertheless
there is still much room to expand globally as well as within Europe most consortia are operating within and
collaborating with research groups in countries where they are based themselves
The level of cooperation and collaboration at a pan-European level hence seems to be limited There
are a few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7 projects
but many research groups are operating locally and are funded by national governments Several survey
respondents reported a low degree of collaboration among different research groups which typically results in
a duplication of efforts and a lack of generalised standards Synergies which could potentially boost research
in artificial photosynthesis are being overlooked Creating for example a communication platform to facilitate
the exchange among researchers could more easily promote the development of knowledge and increase the
speed of discovery and exploitation of new robust (effective and durable) photocatalysts innovative processes
and devices etc Moreover another indicated weakness is the lack of collaboration between already existing
and ongoing projects
While industrial companies are present in a few consortia there is limited collaboration between European
academia and industry Improved collaboration could result in the development of more advanced AP
processes and AP process devices and it might improve the probability of APrsquos successful commercialisation
in the foreseeable future
65
For example Strategic Energy Technology (SET) Plan European Biofuels Technology Platform (EBTP) and European Industrial Bioenergy Initiative (EIBI) JCAP scientific programme For more information please refer to Deliverable 1 Chapter 32
66 By now research funded by the government of Germany in the field of artificial photosynthesis amounts to euro 42 million (httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf)
67 See Deliverable 1
68 httpswwwleopoldinaorgenpolicy-adviceworking-groupsartificial-photosynthesis
76
The long-term focus of AP research is a hurdle for both gaining cooperation with industry and for obtaining
funding Compared to that of its non-European counterparts European funding focuses on the short
term69
While in the USA and Japan funding is dedicated for about 5-10 years European parties often get
funding for about 4 years at the most Although several MS also have dedicated RampD programmes focusing
on AP the amounts provided by non-European counterparts exceed those of the European70
Furthermore
these national programmes are fragmented ie lacking a common goal and perspective hence the funding
of research is also fragmented and scattered71
The European community of researchers could benefit
from an integrated programme which clearly indicates research goals and objectives In addition a common
funding scheme set up to support fundamental research in artificial photosynthesis and to promote
collaboration with industry could advance the research in artificial photosynthesis
A number of survey respondents indicated that there is currently little focus of EU-funded research on
technologies with low TRL within H2020 At the moment there is a strong emphasis on the projects and
technologies which already have a rather high TRL expecting returns in the near future while research in the
area of low TRL technologies requires some attention and funding Several respondents mentioned that there
exist still quite some barriers regarding the design of low-cost materials with low TRL and with higher stability
and activity (eg performance of devices when it comes to a discontinuous supply of energy)72
45 Main industrial actors active in AP field
451 Industrial context
The idea behind artificial photosynthesis is that solar fuels could solve worldwide energy problems by using
water and carbon dioxide and converting them into the fuels we need Artificial photosynthesis can convert
sunlight directly into chemical fuels which makes it possible to harvest and store energy However there are
still many obstacles to make this technology commercially viable Only if artificial photosynthesis can be
provided efficiently stably safely and cheaply will it be beneficial for the public This means inter alia that an
efficient light absorber and catalysts need to be created to convert sunlight into fuel Even though there are
rapid developments in the field of artificial photosynthesis there are many obstacles to overcome in order to
reach mass production Currently the positioning of the fields of artificial photosynthesis and solar fuels is at
around a 3 on the technology readiness level
452 Main industrial companies involved in AP
At the moment the number of companies active in the field of AP is limited Based on our analysis of the main
AP actors in the industry only several tens of companies appear to be active in this field Moreover industrial
activity is limited to research and prototyping as viable AP technologies have not (yet) been commercialised
35 companies active in the field of AP have been identified comprising 16 European companies and 19 non-
European companies (Table 410) Seven of these are in Germany eight in the Netherlands eight in Japan
and 10 in the US The following table summarises the countries in relation to one or more of the technology
pathways
69
Already in 2013 it was indicated that much of public funding of basic AP research remains short term For more information see Thomas FaunceStenbjorn Styring Michael R Wasielewski Gary W Brudvig A William Rutherford et al (2013) Artificial Photosynthesis as a Frontier Technology for Energy Sustainability Energy amp Environmental Science Issue 4 2013
70 A number of respondents indicated that the available funding is not sufficient to finance research facilities and equipment
71 This weakness is indicated by several respondents
72 This is also mentioned as one of the areas of attention in Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press)
77
Table 410 Overview of the size of the industrial community number of companies per pathway
Country Synthetic biology amp
hybrid systems
Photoelectrocatalysis Co- electrolysis Total number of
companies
European companies
France 1 1 0 1
Germany 2 2 0 4
Italy 0 1 0 1
Netherlands 3 4 1 8
Switzerland 0 1 0 1
Total 6 9 1 15
Non-European companies
Japan 0 8 0 8
Saudi Arabia 0 1 0 1
Singapore 0 0 1 1
US 3 2 4 8
Total 3 11 5 19
Note a company can be active in multiple technology pathways
Source Ecorys
With respect to the industry largely the same countries stand out as in the research field namely Japan the
US and north-western Europe The industry in Japan appears to have the most intensive research activities
in AP as several large Japanese multinationals have set up their own AP RampD laboratoriesresearch
departments
With respect to the three technology pathways (i) synthetic biology amp hybrid systems (ii) photoelectrocatalysis
and (iii) co-electrolysis we have observed that most industrial (research) activity is being performed
concerning photoelectrocatalysis (19 companies) although there are also companies active in the two other
pathways
We have also identified a number of companies active in the area of carbon capture and utilisation that might
potentially be involved in the research of artificial photosynthesis
453 Companies active in synthetic biology amp hybrid systems
The pathway involving synthetic biology amp hybrid systems is still at an early stage on the TRL scale (TRL 1-2)
The challenges industries face relate mostly to efficiency obstacles Enzymes and proteins need to be
modified by genetic engineering Another barrier relates to the fact that the modifications and protein
production are still very time-consuming in terms of cell growthprotein purification Furthermore it is
necessary to improve protein stability and solubility by rational design directed evolution and modifying
sample conditions since currently proteins are unstable It would probably take about 10-20 years until
technologies reach TRL 7
The companies involved in this pathway range from chemical and oil-refining companies companies working
on bacteria companies producing organic innovative catalysts to others The following table lists the
organisations identified within this pathway
78
Table 411 Organisations in synthetic biology amp hybrid systems
Country Organisation (in EN)
France PhotoFuel
Germany Evonik Industries AG
Germany Brain AG
Italy Hysytech
Netherlands Biomethanol Chemie Nederland BV
Netherlands Photanol BV
Netherlands Tendris Solutions
Netherlands Everest Coatings
US Joule Unlimited
US Phytonix
US Algenol
Source Ecorys
Chemical and oil-refining companies
Biomethanol Chemie Nederland BV a Dutch company that produces and sells industrial quantities of high
quality bio-methanol focusing on synthetic biology amp hybrid systems is also a partner of the BioSolar Cells
programme The BioSolar Cells programme focuses its research on artificial photosynthesis photosynthesis in
cellular systems and photosynthesis in plants
Companies working on bacteria
Another group of companies in the pathway of synthetic biology amp hybrid systems focus on CO2 to fuel
processes that use cyanobacteria to convert CO2 into targeted fuels or chemicals (biological conversion)
Examples of such companies are Joule Unlimited Phytonix and Algenol all based in the US Algenol is
commercialising its patented algae technology platform for the production of ethanol using proprietary algae
sunlight carbon dioxide and saltwater The Dutch company Photanol uses cyanobacteria to turn CO2 into
certain predetermined products
Companies producing organic innovative catalysts
Many of the smaller companies currently active in developing AP originate from a specific research group or
research institute and focus on specific AP process steps andor process components Some companies
focus on the further development of both chemical and organic innovative catalysts which are earth-abundant
non-toxic and inexpensive Brain AG (Germany) is an example of such a company
Other companies
Hysytech is an Italian company experienced in technology development and process engineering applied to
the design and construction of plants and equipment for fuel chemical processing energy generation and
photoelectrocatalysis Hysytech is involved in an FP7 project to develop a fully artificial photoelectrochemical
device for low temperature hydrogen production
Other companies in the field of synthetic biology amp hybrid systems are Tendris Solutions (Netherlands) and
Everest Coatings (Netherlands) involved in the EET-Kiem project which focused on increasing the
absorption of visible light in the TiO2 photocatalyst by incorporating other elements in the structure and to
construct a photoelectrochemical reactor Photofuel in France and Phytonic in the US focus on synthetic
biology amp hybrid systems and photoelectrocatalysis Evonik Industries AG invests in synthetic biology amp
hybrid systems as well as carbon capture technologies which convert waste CO2 into products and fuels
79
454 Companies active in photoelectrocatalysis
The pathway of photoelectrocatalysis is relatively low on the TRL scale as well (TRL 1-4)
Photoelectrocatalysis would make it possible to use photovoltaic cells that absorb photons to facilitate water
splitting Research on photoelectrocatalysis using photoelectrochemical cells in particular is still at a very early
stage
Technologies pertaining to the photoelectrocatalysis pathway are not yet commercially viable with the main
challenges relating to the design of devices that are efficient stable and durable Further potential obstacles to
be taken into account relate to the incorporation of these technologies with other technologies that can
generate fuel molecules other than hydrogen
Most companies are involved in this pathway ranging from automotive manufacturers and electronic
companies to chemical and oil-refining companies The following table lists the organisations identified within
this pathway
Table 412 Organisations in the field of photoelectrocatalysis
Country Organisation (in EN)
France PhotoFuel
Germany Bauhaus Luftfahrt eV (Bauhaus Luftfahrt Research)
Germany ETOGAS
Italy Hysytech
Japan Toyota (Toyota Central RampD Labs)
Japan Honda (Honda Research Institute - Fundamental Technology Research Center)
Japan Mitsui Chemicals
Japan Mitsubishi (Mitsubishi chemicals Setoyama Laboratory)
Japan Sumitomo Chemicals (Energy amp Functional Materials Research Laboratory)
Japan INPEX Corporation
Japan Toshiba (Corporate Research and Development Center)
Japan Panasonic (Corporate Research and Development Center)
Netherlands InCatT BV
Netherlands Shell (Shell Game Changer Programme)
Netherlands Hydron
Netherlands LioniX BV
Saudi Arabia Saudi Basic Industries Corporation
Switzerland SOLARONIX SA
US HyperSolar
Source Ecorys
Companies in the automotive sector
Several automotive manufacturers are active in the field of AP mostly relating to the field of
photoelectrocatalysis In 2012 Honda opened a hydrogen station in Saitama Japan that converts sunlight
into hydrogen that could be used to power fuel-cell electric vehicles The station is focusing on
photoelectrocatalysis and turning sunlight into hydrogen via a high-pressure water electrolysis system that
was developed by Honda itself Since then there seems to be little activity from Honda73
73
httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
80
Figure 44 Hondarsquos sunlight-to-hydrogen station
Source httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
Toyota succeeded (in 2011) to generate organic compounds via artificial photosynthesis without using any
external energy andor material sources The system is focused on producing formic acid (which could be
used as a raw material in industry) In February 2016 Toyota Central RampD Labs announced that they
achieved the worldrsquos highest energy conversion efficiency rate of 46 with artificial photosynthesis using
water and carbon dioxide as raw materials and sunlight as energy to produce useful materials Toyota is also
researching new chemical reactions to generate more valuable organic compounds as a final product such as
methanol Toyota is primarily focused on photoelectrocatalysis The companyrsquos 2020 goal is to complete basic
testing for the creation of primary CO2-absorbing materials (material or fuel)74
Electronic companies
In addition to car manufacturers also electronic companies are involved in photoelectrocatalysis In December
2014 Toshiba announced its focus on producing a catalyst made of gold The company indicated that they
found a way to modify gold at the atomic level using nanotechnology which allows carbon dioxide to change
into other compounds at a lower voltage (with a record of 15 energy efficiency rate)75
In September 2015 Toshiba made public that the company developed a prototype of a new highly efficient
molecular catalyst (consisting of an imidazolium salt) that converts carbon dioxide into ethylene glycol without
producing other and unwanted by-products Most artificial photosynthesis technologies use a two-electron
reduction conversion process producing carbon monoxide and formic acid Others can achieve direct multi-
electron reduction but tend to produce many by-products and their separation can be problematic Toshibas
new molecular catalyst converts carbon dioxide into ethylene glycol via multi-electron reduction The long-term
goal of Toshibarsquos research work is to develop a technology compatible with carbon dioxide capture systems
installed at facilities such as thermal power stations and factories utilising carbon dioxide to provide (storable)
energy To this end Toshiba focuses on photoelectrocatalysis and further improvement of the conversion
efficiency by increasing catalytic activity and aims at practical implementation in the 2020s76
Panasonics artificial photosynthesis system is also focused on photoelectrocatalysis in particular on highly
efficient CO2 conversion which can utilise direct sunlight or focused light In 2012 Panasonic found that a
nitride semiconductor has the capability to excite the electrons with enough high energy for the CO2 reduction
reaction to take place Nitride semiconductors have attracted attention for their potential applications in highly
74
httpwwwtytlabscom and httpswwwasiabiomassjpenglishtopics1603_01html 75
httpwwwjapantimescojpnews20150412nationalscience-healthlab-photosynthesis-begins-to-bloomVw1YZP5f3IV 76
httpswwwtoshibacojprdcrddetail_ee1509_01html
81
efficient optical and power devices for energy saving However its potential was revealed to extend beyond
solid devices more specifically it can be used as a photoelectrode for CO2 reduction By making a devised
structure through the thin film process for semiconductors the performance as a photoelectrode has greatly
improved77
In September 2014 Panasonic Corporation managed to achieve a conversion efficiency rate of
0378
and not long after that the company announced to having achieved the first formic acid generation
efficiency of approximately 10 as of November 201479
According to Panasonic the key to achieving an
efficient artificial photosynthetic system lies in improved photoelectrodes and oxidation-reduction electrodes
Chemical and oil-refining companies
The developments with respect to solar fuels are also being supported by several chemical and oil-refining
companies Artificial photosynthesis has been an academic field for many years However in the beginning of
2009 Mitsubishi Chemical Holdings reported to be undergoing its own artificial photosynthesis research by
using sunlight water and carbon dioxide to create the carbon building blocks from which resins plastics and
fibres can be synthesisedrdquo80
In 2014 Mitsubishi established the research organisation Setoyama Laboratory
The Laboratory focuses on the development of artificial photosynthesis for chemical processes which is the
synthesis of raw materials such as ethylene propylene butenes etc by means of solar hydrogen obtained by
catalytic water splitting under visible light and CO2 emitted at a plant site81
The laboratory is also participating
in the ldquoArtificial Photosynthetic Chemical Processrdquo project (denoted ldquoARPChemrdquo) granted by NEDO (New
Energy Development Organization) In this project the following three programmes are conducted through
collaboration with academia and industry
1 Design of a photo semiconductor catalyst for water splitting
2 A membrane separation system for H2 from gas mixtures composed of H2 and O2 and
3 A catalytic process for the synthesis of lower olefins from H2 and CO2
The Japanese chemical companies Sumitomo chemicals and Mitsui Chemicals focusing on carbon
capture and photoelectrocatalysis are also participating in the ARPChem programme Sumitomo has its
own Energy amp Functional Materials Research Laboratory and is conducting research and development in a
broad range of fields Mitsui created the Mitsui Chemicals Catalysis Science Award and the Mitsui Chemicals
Catalysis Science Award of Encouragement in order to award recognition to national and international
researchers that have made substantial contributions to the field of catalysis science In 2014 it was the fifth
time that Mitsui has given these awards
Royal Dutch Shell cooperated with Bauhaus Luftfahrt in the EU-funded Solar-Jet project (2011-2015) in the
area of photoelectrocatalysis aimed at demonstrating an innovative process technology using concentrated
sunlight to convert carbon dioxide and water into synthesis gas (syngas) The syngas a mixture of hydrogen
and carbon monoxide is ultimately converted into kerosene by means of the commercial Fischer-Tropsch
technology With the first ever production of synthesised ldquosolarrdquo jet fuel the SOLAR-JET project has
successfully demonstrated the entire production chain for renewable kerosene obtained directly from sunlight
water and carbon dioxide (CO2)82
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University (US)
SOFI leads a global consortium that brings together universities from Rutgers University in New Jersey to
Uppsala University in Sweden83
SOFI focuses on both the water-splitting process (production of hydrogen)
and the CO2 reduction process (the reduction of carbon dioxide to carbon monoxide which in combination
77
httpnewspanasoniccomglobalpressdata201207en120730-5en120730-5html 78
httpswwwasiabiomassjpenglishtopics1603_01html 79
httpwwwpanasoniccomglobalcorporatetechnology-designtechnologyphotosynthesishtml 80
httpwwwdigitalworldtokyocomindexphpdigital_tokyoarticlesmanmade_photosynthesis_looking_to_change_the_world 81
httpwwwmcrccojpenglishrdsetoyama_laboratoryhtml 82
httpwwwsolar-jetaeropagepostsartsunlight-to-jet-fuel-european-collaboration-solar-jet-for-the-first-time-demonstrates-the-entire-production-path-of-ldquosolarrdquo-kerosene-4php
83 httpappsnorthbynorthwesterncommagazine2015springsofi
82
with hydrogen can be processed into eg methanol or synthetic gasoline) Total is also a partner of the
BioSolar Cells programme
INPEX Corporation is a Japanese oil company established in February 1966 as North Sumatra Offshore
Petroleum Exploration Co In addition to Mitsubishi Chemicals Sumitomo Chemicals and Mitsui Chemicals
INPEX also participates in the ldquoJapan Technological Research Association of Artificial Photosynthetic
Chemical Processrdquo (ARPChem) programme and engages in RampD projects with the aim to produce chemical
products like plastics and hydrocarbon fuel from photochemical catalysis INPEX Corporation is focused on
photoelectrocatalysis
Other companies
Other companies include Etogas (Germany) which develops builds and selects Power-to-Gas plants and
products related to Power-to-Hydrogen Power-to-SNG and Hydrogen-to-SNG LnCatT BV (Netherlands)
Hydron (Netherlands) Saudi Basic Industries Corporation (Saudi Arabia) and Hyper Solar () all focus on
photoelectrocatalysis LioniX BV (Netherlands - photoelectrocatalysis) and Solaronix SA (Switzerland -
photoelectrocatalysis) are focused on the further development of photoelectrochemical cells Hysytech and
Photofuel are in addition to the first pathway also involved in the second
455 Companies active in co-electrolysis
Even though co-electrolysis is the pathway at the highest levels of technical readiness compared to the other
two pathways not many companies are involved in it There are three electrolyser types capable of producing
hydrogen gas eg alkaline electrolysis polymer electrolyte membrane electrolysis and solid oxide electrolysis
cells (SOECs) Multiple designs are commercialised although SOECs using Fischer-Tropsch synthesis are
not yet commercially viable The companies involved in this pathway are mainly from the US Industries
combine co-electrolysis and the field of carbon capture Fuel cell products are used in the automotive
telecom defenceaerospace and consumer product sectors
The following table summarises the organisations in the field of co-electrolysis
Table 413 Companies in co-electrolysis
Country Organisation (in EN)
Netherlands Shell (Shell Game Changer Programme)
Singapore Horizon Fuel Cell Technologies
US Catalytic Innovations
US Opus 12
US LanzaTech
US Proton onsite
Source Ecorys
Companies include Proton onsite (US ndash PEM electrolysis) which manufactures hydrogen nitrogen and zero
air generators in a safe reliable and cost-effective way Horizon Fuel Cell Technologies (Singapore)
focuses on commercially viable fuel cells starting by simple products which need smaller amounts of
hydrogen The technology platform of horizon fuel cell technology is focused on three main topics PEM fuel
cell systems hydrogen supply and hydrogen storage Catalytic Innovations (US) Opus 12 (US) Lanzatech
(US) and Shell (NL) are also involved in the second pathway
83
456 Companies active in carbon capture and utilisation
The technology in the carbon capture and storage pathway can capture up to 90 of the CO2 and allows for
the separation of carbon dioxide from gases produced in electricity generation and industrial processes by
means of combustion capture and oxyfuel combustion The most advanced technologies are at TRL 7 eg
carbon capture in a coal plant
The following table shows the organisations active in the field of carbon capture and utilisationre-use
Table 414 Organisations active in carbon capture and utilisation
Country Organisation (in EN)
Denmark Haldor Topsoe
Germany Evonik Industries AG
Germany Siemens (Siemens Corporate Technology CT)
Germany Sunfire GmbH
Germany Audi
Switzerland Climeworks
UK Econic (Econic Technologies)
Canada Carbon Engineering
Canada Quantiam
Canada Mantra Energy
Iceland Carbon Recycling International
Israel NewCO2Fuels
Japan Mitsui Chemicals
US Liquid light
US Catalytic Innovations
US Opus 12
US LanzaTech
US Global Thermostat
Source Ecorys
Twelve companies currently only focus on carbon capture and utilisation These companies are therefore
technically not considered to be companies involved in artificial photosynthesis However they can potentially
be involved in AP research in the future Such companies include automotive manufacturers as well as
electronics companies Five companies are involved in carbon capture and one of the pathways
Automotive manufacturers
Audi is working together with the American company Joule Unlimited in order to research and produce lsquoe-
ethanolrsquo Joule optimised a production process in which microorganisms are able to produce and excrete
either ethanol or alkanes from carbon dioxide (CO2) and sunlight Audi and Joule opened a joint
demonstration plant in September 2012 where e-ethanol is produced in transparent plastic tubes (see Figure
45)
84
Figure 45 Demonstration facility of Audi and Joule in Hobbs (New Mexico)
Source httpwwwbest-practicesfrost-multimedia-wirecomjoule2015
In January 2014 Audi e-ethanol underwent its first-ever test cycle in the pressure chamber and glass engine
showing that fewer pollutants are produced in the combustion of e-ethanol than is the case with bio-ethanol84
Since 2011 Audi has also been collaborating with Joule to produce e-diesel Finally in November 2014 Audi
opened a research facility in Dresden with project partners Climeworks and the start-up Sunfire in order to
produce its first batches of synthetic diesel combining two innovative technologies CO2 capture from the
ambient air (Climeworks) and the power-to-liquid process for the production of synthetic fuel (Sunfire)85
Currently Audi is investing in carbon capture and utilisation technologies
Electronics companies
Electronics companies such as Siemens are also investing in carbon capture technologies Developers at
Siemens Corporate Technology (CT) in Munich are currently active in the project CO2-to-value The challenge
of the project is to charge only carbon dioxide with electrons and not the surrounding water molecules
because the latter would merely result in the production of conventional hydrogen Specialists at the University
of Lausanne in Switzerland and materials scientists at the University of Bayreuth are working with Siemens to
develop catalysts on their behalf Siemens takes on a pragmatic approach by focusing on only one step in the
AP process They are not yet trying to capture light Instead they are centring their research activities on
activating CO2 and converting it into products such as (i) ethylene which the chemical industry needs for the
production of plastics (ii) methane the main component of natural gas and (iii) carbon monoxide which can
be used to produce fuels such as ethanol86
Other companies
Figure 46 illustrates the process of NewCO2Fuels (NCF) an Israeli company focused on carbon capture
This is a high-temperature-driven CO2- and water-dissociation process that produces syngas (a mixture of
CO and H2) from which various synthetic fuels and chemicals can be produced
In the short term NCF is focusing on the design and building of a first pilot plant as well as raising the
necessary funds for it
In the mid term NCF plans to offer its technology to the energy intensive industries such as the steel
gasification and glass industries to transform their CO2 waste streams into feedstock
In the long term NCFrsquos vision is to use solar energy to convert CO2 captured immediately from the
atmosphere into valuable products
84
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 85
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 86
httpwwwsiemenscominnovationenhomepictures-of-the-futureresearch-and-managementmaterials-science-and-processing-co2tovaluehtml
85
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels
Source httpwwwnewco2fuelscoilproduct8overview
Furthermore some companies focus on chemical or biological CO2-to-fuel production Examples of
companies that focus on direct (co-electrolysis) CO2 to fuels production are Carbon Recycling (Iceland) and
Econic (UK ndash carbon capture) The company Liquid Light (US ndash carbon capture) focuses on the
electrochemical conversion of CO2 to chemicals
Other companies involved in carbon capture are Global Thermostat (US) Quantiam (Canada) Carbon
Engineering (Canada) Evonik Industries AG (Germany) and Haldor Topsoe (Denmark) Besides co-
electrolysis Catalytic Innovations Opus 12 and Lanzatech are also involved in carbon capture Mitsui
Chemical is focusing on carbon capture as well as photoelectrocatalysis
457 Assessment of the capabilities of the industry to develop AP technologies
Although there is a lot of research activity going on in the field of AP both at the academic and industrial level
the technology is clearly not yet ready for commercialisation However concrete test facilities and prototypes
are being developed and solar fuels have already been produced at a laboratory scale The technology is not
yet sufficiently efficient in order to be able to compete with other technologies producing comparable
chemicals and fuels Finding catalysts which are on the one hand Earth-abundant non-toxic and inexpensive
and on the other hand sufficiently efficient seems to be the biggest challenge With respect to the
technological efficiency of the AP processes the main bottlenecks are light capture (whole spectrum) getting
a good photocurrent density and using these charge carriers efficiently87
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade In September 2014 Panasonic Corporation managed to achieve a conversion
efficiency rate of 03 becoming the first to exceed the rate of 02 for regular plants In November 2014
Toshiba reached 15 which was followed by 20 achieved by the Japan Technological Research
Association of Artificial Photosynthetic Chemical Process (ARPChem) in February 2015 In February 2016
Toyota Central RampD Labs Inc announced that they achieved the worldrsquos highest energy conversion
efficiency rate of 46 with artificial photosynthesis by developing a semiconductor substrates-using iridium
and ruthenium catalyst They succeeded in increasing the efficiency rate a hundred-fold (an efficiency rate of
004 had been in achieved by Toyota in 2011)88
Figure 47 summarizes these efficiency rate developments
Several companies (eg Toshiba) hint at achieving efficiency rates of 10 and the first practical applications
87
httpwwwosa-opnorghomearticlesvolume_24february_2013featuresartificial_photosynthesis_saving_solar_energy_for 88
httpswwwasiabiomassjpenglishtopics1603_01html
86
of AP in the 2020s ARPChem aims to achieve a 10 level of energy conversion efficiency in 2021 (the rate
at which the manufacturing of raw materials for chemicals becomes economically viable)89
Figure 47 Transition of energy conversion efficiency of artificial photosynthesis
Source httpswwwasiabiomassjpenglishtopics1603_01html
It can also be observed that the big industrial investors in AP technology (research) already built interesting
partnerships with research centres and new innovative start-upscompanies For example
Audi works together with the innovative company Joule Unlimited (US) on the development of biologically-
derived e-ethanol and e-diesel and also works together with start-up company Sunfire on the production
of synthetic diesel
Siemens works together with specialists at the University of Lausanne in Switzerland and at the University
of Bayreuth Germany on innovative catalysts
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University
(US) that works on the water-splitting and CO2 reduction process and
Mitsubishi is one of the five industrial partners in the Japanese ARPChem programme (2012-2021)
focusing on artificial photosynthesis research in which various Japanese universities will be involved
(including Waseda University and Tokyo University)
46 Summary of results and main observations
The aim of this report was to gain an understanding and a clear overview of the main European and global
actors active in the field of artificial photosynthesis This has been achieved by
Identifying the main European and global actors active in the field of AP
Providing an assessment of the current level of investments in AP technologies
Assessing the key strengths and weaknesses of the main actors and
Assessing the capabilities of the industry to develop and exploit the AP technologies
Fuelled by the globally perceived need to find a green non-polluting and emission neutral energy source for
the future there has been much development in the field of artificial photosynthesis and considerable progress
has been made In addition the emergence of multiple consortia and governmental programmes and
international conferences in the last 10-15 years suggest that there is a higher awareness of the potential of
89
httpwwwmitsubishichem-hdcojpenglishcsrdownloadpdf13_25pdf
87
AP and that further advances are necessary The analysis has shown that although there have been some
promising developments especially in collaboration with industry much remains to be done for AP
technologies and processes to become commercially viable Milestones which will spur the development and
commercialisation process of AP encompass increased global and industry cooperation and the deployment
of targeted large-scale innovation projects following the example of the US innovation hubs
A summary of the results of the analysis and the main observations concerning the research and industry
actors active in the field of artificial photosynthesis is presented below It should be noted that the academic
and industrial community presented in this report is not exhaustive and especially with increasing interest in
AP more actors are expected to become active in the field
Research community
In general we observe that AP research has been intensified during the last decade given the increasing
number of emerging networks and communities We identified more than 150 research groups on AP
worldwide out of which more than 60 are located in Europe Due to the interdisciplinary character of AP
research combines expertise from biology biochemistry biophysics and physical chemistry The development
of research networks and consortia facilitates collaboration between different research groups and enables
them to benefit from synergies We identified six consortia in Europe and five outside of Europe respectively
Almost all of them are based in a specific country attracting primarily research groups from that country Only
one consortium AMPEA launched by the European Energy Research Alliance is truly pan-European with a
range of members across the EU
Table 415 Summary of findings size of research community
Number of research groups
Total in Europe 113
Number of research groups per pathway
Synthetic biology amp hybrid systems 53
Photoelectrocatalysis 69
Co-electrolysis 25
Total outside Europe 77
Number of research groups per pathway
Synthetic biology amp hybrid systems 30
Photoelectrocatalysis 59
Co-electrolysis 14
Source Ecorys
With respect to the three technology pathways (synthetic biology amp hybrid systems photoelectrocatalysis and
co-electrolysis) we observed that almost 85 of the research activities worldwide are focused on the first two
pathways (about 34 on the first pathway and 50 on the second) whereas the third pathway attracts only
about 16 of the research communityrsquos attention Only the Dutch AP consortium BioSolar Cells specifically
focuses on co-electrolysis Other consortia like ARPChem in Japan collaborating with industry prefer to
research artificial photosynthesis via photoelectrochemical catalysis as this pathway is the most mature and
with the highest probability of successful commercialisation
The diversity of the scientists involved is the biggest strength of this global AP research community
Furthermore all of the existing technological pathways in AP are covered which avoids lock-ins into one
pathway and increases the probability of success for AP in general AP is on the research agenda of several
countries which is proven by the existence of dedicated programmes roadmaps and funds Globally several
hundreds of millions of euros are being spent this decade on AP research and these investments seem to be
intensifying further Major shortcomings encompass a lack of cooperation between research groups in
88
academia on the one hand and between academia and industry on the other A more technical challenge is
the transfer of scientific insights into practical applications and ultimately into commercially viable products
The AP sector in Europe exhibits some strengths in comparison to its non-European counterparts but also
some weaknesses Europersquos scientific institutions are strong and its researchers highly educated
Furthermore RampD institutions and research facilities are available providing a solid ground for research
Some individual MS have their own research programmes roadmaps and funds Nevertheless the investment
does not reach the amount of funds available in some non-European countries and is rather short-term in
comparison to that of its non-European counterparts Furthermore both the national research plans and their
funding seem fragmented and scattered lacking an integrated approach with common research goals and
objectives At the European level however collaboration has been successful within several ongoing and
conducted FP7 projects Close collaboration between research groups could also be achieved through the
establishment of consortia Apart from the pan-European consortium AMPEA collaboration between research
groups of different countries is limited the consortia are primarily country-based and attract mostly research
groups from that respective country Lastly the level of collaboration between academia and industry seems
to be more limited in Europe compared to that within the US or Japan
Industrial actors
At this moment the number of companies active in the field of AP is limited AP is still mainly at the laboratory
level Most pathways are still at level 1 or 2 of technology readiness (TRL) implying that research is still being
conducted and used to improve feasibility Only co-electrolysis is at a more advanced stage and most
methods are already commercially viable
Based on our analysis of the main AP actors in the industry only several tens of companies appear to be
active in this field Moreover the industrial activity is limited to research and prototyping as viable AP
technologies are not (yet) in commercial operation The pathways synthetic biology amp hybrid systems and
photoelectrocatalysis are still at the lowest levels of technology readiness Research within the
photoelectrocatalysis pathway is still at an early stage as well however PV devices (semiconductor devices
similar to the ones used in PEC devices) have already been successfully commercialised Co-electrolysis on
the other hand is a technology already available for a longer time period in this pathway various
technologies to convert water and DC electricity into gaseous hydrogen and oxygen are already
commercialised In contrast the technologies producing hydrocarbons by Fischer-Tropsch synthesis
converting for example CO2 H2O and syngas into hydrocarbon fuels are still at an earlier stage of
development Co-electrolysis is therefore at a 1-9 TRL having both already commercialised technologies as
well as the Fischer-Tropsch synthesis
In total we have identified and analysed 33 industrial actors active in the field of AP 15 European and 18 non-
European industrial actors With respect to the industry largely the same countries stand out as in the
research field namely Japan the US and north-western Europe The industry in Japan appears to have the
most intensive research activities in AP as several large Japanese multinationals have set up their own AP
RampD laboratoriesresearch departments With respect to the three technology pathways we can observe that
most industrial (research) activity is being performed concerning photoelectrocatalysis
89
Table 416 Summary of findings size of industrial community
Number of companies
Total in Europe 15
Number of companies per pathway
Synthetic biology amp hybrid systems 6
Photoelectrocatalysis 9
Co-electrolysis 1
Total outside Europe 18
Number of companies per pathway
Synthetic biology amp hybrid systems 3
Photoelectrocatalysis 11
Co-electrolysis 5
Source Ecorys
The main hurdles in the synthetic biology amp hybrid systems pathway relate to the improvement of efficiency
and protein production speeds as well as stability and solubility by rational design With respect to the
technological efficiency of the AP processes relating to photoelectrocatalysis the main bottlenecks are light
capture (whole spectrum) obtaining a good photocurrent density and using these charge carriers efficiently
Co-electrolysis is mainly facing challenges to increase the lifetime of the devices to create concept on a
megawatt scale to search for substitution of noble metal catalysts and to develop technologies that are
capable of supplying the electricity required Furthermore some methods are still at a low TRL like the
Fischer-Tropsch synthesis Finding catalysts which are Earth-abundant non-toxic inexpensive and
sufficiently efficient remains a huge challenge To this end more public and private funding is needed
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade For example between 2011 and 2016 Toyota Central RampD labs made a significant
leap forward from an efficiency rate of 004 towards an efficiency rate of 46 Furthermore several
industrial actors (including Toshiba and ARPChem) have hinted at being able to achieve efficiency rates of
10 and the first practical applications of AP in the 2020s When academia are able to overcome the main
barriers with respect to AP the TRL will increase and the interest in AP from the industries will rise More
interest from the industries is necessary in order to push AP on the market and making it an economically
viable alternative renewable energy source
91
5 Factors limiting the development of AP technology
The overall concept followed in this study is to assess a number of selected ongoing research technological
development and demonstration (RTD)initiatives andor technology approaches implemented by European
research institutions universities and industrial stakeholders in the field of AP (including the development of
AP devices)
Seven AP RTD initiatives have been identified for the assessment of ldquolimiting factorsrdquo addressing the three
overarching technology pathways synthetic biology amp hybrid systems photoelectrocatalysis of water (water
splitting) and co-electrolysis (see Table 51)
The authors are confident that through the assessment of these selected European AP RTD initiatives a good
overview of existing and future factors limiting the development of artificial photosynthesis technology (in
Europe) can be presented However it has to be noted that additional AP RTD initiatives by European
research institutions universities and industrial stakeholders do exist and that this study does not aim to prove
a fully complete inventory of all ongoing initiatives and involved stakeholders
Table 51 Overview of the selected AP research technological development and demonstration (RTD) initiatives
AP Technology
Pathways AP RTD initiatives for MCA
Synthetic biology amp
hybrid systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Biocatalytic conversion of CO2
into formic acid ndash Bio-hybrid
systems
Photoelectrocatalysis
of water (light-driven
water splitting)
Direct water splitting with bandgap absorber materials and
catalysts
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
a) Direct water splitting with III-
V semiconductor ndash Silicon
tandem absorber structures
b) Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Co-electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
Electrolysis cells for CO2
valorisation ndash Industry
research
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges
Until today much progress has been made in the development of artificial photosynthetic systems
However a number of significant scientific and technological challenges remain to successfully scale-up
existing laboratory prototypes of different AP technology approaches towards a commercial scale
In order to ensure that AP technologies become an important part of the (long-term) future sustainable
European and global energy system and additionally provide high-value and low carbon chemicals for
industrial applications AP based production systems need to be
Efficient so that they utilise as much sunlight as possible to produce fuels andor chemicals The larger
the fraction of sunlight that can be converted to chemical energy the fewer materials and less land would
be needed for AP devices A target efficiency of about 10 (for AP based fuel production) is an initial goal
This is about ten times the efficiency of natural photosynthesis however it should be noted that AP
92
laboratory prototype devices with solar-to-hydrogen efficiencies of 5 and more have already been
developed
Durable so that AP systems can convert a lot of energy in their lifetime relative to the energy required for
the production and installation of the devices This is a significant challenge because some materials
degrade quickly when operated under the special conditions of illumination by discontinuous sunlight
Cost-effective meaning the raw materials needed for the production of the AP devices have to be
available at a large scale and the produced fuels andor chemicals have to be of commercial interest
Resource-efficient so that they minimise the use of rare and expensive raw materials (taking into
account trade-offs between material abundancy cost and efficiency)
Today significant improvements with respect to cost-efficiency lifetimedurability energy efficiency and
resource use are still required for all existing AP technology approaches
Table 52 provides an overview of the current and target performance for the assessed seven AP research
technological development and demonstration (RTD) initiatives within the three overarching technology
pathways of synthetic biology amp hybrid systems photoelectrocatalysis and co-electrolysis
93
Table 52 Overview of the current and target performance with respect to cost-efficiency lifetimedurability energy efficiency and resource use
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
Nitrogenase
activity wanes
within a few
days
Light energy
conversion
efficiency
gt10
(theoretical
limit ~15)
4 (PAR
utilization
efficiency) on
lab level (200 x
600 mm)
No data No data
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
CO2 reduction
energy
efficiency (full
system) gt10
(nat PS ~1)
NA (CO2
reduction
energy
efficiency for
full system) on
lab level
No data No data
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
gt500 hours
(stability goal)
gt40 hours
Solar-to-
hydrogen
(STH)
efficiency
gt17
STH efficiency
14
Reduction of
use of noble
metal Rh
catalyst and
use of Si-
based
substrate
material
1kg Rh for
1MW
electrochem
power output
Ge substrate
(for
concentrator
systems)
Si substrate
94
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Bandgap abs materials
Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency ~9
STH efficiency
49
Reduction of
use of rare Pt
catalyst
Pt used as
counter
electrode for
H2 production
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency
gt10
IPCE gt90
(efficiency
goal)
IPCE (incident
photon to
electron
conversion
efficiency) of
25
Reduction of
use of rare and
expensive raw
materials
High-cost Ru-
based photo-
sensitizers
used
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
SOFC capital
cost target
400 US$kW
Comp of
synthetic fuels
with fossil fuels
No data
gt20 years
(long term)
1000 hours
(stability goal)
~50 hours
(high SOEC
cell
performance
degradation
observed)
Power-to-
Liquid system
efficiencies
(full system
incl FT)
gt70
No data No data No data
Electrolysis cells for CO2
valorisation ndash Industry
research
Comp with
fossil chemi
and fuels (eg
CO ethylene
alcohols) 650-
1200 EURMt
No data
gt20 years
(long term)
10000 hours
(stability goal)
gt1000 hours
(laboratory
performance)
System
efficiencies
(full system)
gt60-70
95 of
electricity used
to produce CO
System
efficiencies
(full system)
40
No data No data
95
52 Current TRL and future prospects of investigated AP RTD initiatives
Table 53 presents an overview of the current TRL future prospects and an estimation of future required
investments for the assessed AP research technological development and demonstration (RTD) initiatives
It should be noted that due to the focus on specific selected AP RTD initiatives the investment requirements
listed below do not represent all of the RTD activities conducted by European research institutions
universities and industrial stakeholders within the three overarching technology pathways of synthetic biology
amp hybrid systems photoelectrocatalysis and co-electrolysis
Table 53 Overview of current TRL future prospects and estimated investment needs for investigated AP RTD initiatives
AP RTD Initiatives TRL achieved (June
2016)
Future Prospects Estimated Investment
needed
Photosynthetic microbial cell
factories based on cyanobacteria
TRL 3 (pres Init)
TRL 6-8 (for direct
photobiol ethanol prod
with cyanobacteria green
algae)
2020 TRL 4 (pres Init)
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Biocatalytic conversion of CO2 into
formic acid ndash Bio-hybrid systems TRL 3 2020 TRL 4
Direct water splitting with III-V
semiconductor ndash Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 (for III-VGe
tandem structures)
TRL 3 (for III-VSi tandem
structures)
2020 TRL 5 (for III-VGe
tandem structures)
2021 TRL 5 (for III-VSi
tandem structures)
Basic RTD 5-10 Mio euro
TRL 5 5-10 Mio euro
Direct water splitting with Bismuth
Vanadate (BiVO4) - Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 2020 TRL 5
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
TRL 3 2020 TRL 4
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
TRL 2-3 (for co-
electrolysis of H2O
(steam) and CO2)
2020 TRL 3-4 (for co-
electrolysis of H2O
(steam) and CO2)
Electrolysis cells for CO2
valorisation ndash Industry research
TRL 4 (for RE assisted
carbon compound
production)
TRL 3 (for full synthetic
photosynthesis systems)
2020 TRL 6 (for RE
assisted carbon
compound production)
2020 TRL 5 (for full
synthetic photosynthesis
systems)
TRL 6 10-20 Mio euro
53 Knowledge and technology gaps of investigated AP RTD initiatives
At present a number of significant scientific and technological challenges remain to be addressed before
successfully being able to scale-up existing laboratory prototypes of different AP technology approaches
towards the commercial scale
Table 54 presents an overview of the identified knowledge and technology gaps focusing on the assessed
AP research technological development and demonstration (RTD) initiatives
96
Table 54 Overview of knowledge and technology gaps of investigated AP RTD initiatives
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Photosynthetic microbial cell
factories based on
cyanobacteria
Further metabolic and genetic engineering of the strains
Further engineered cyanobacterial cells with respect to increased light
harvesting capacity
Streamlined metabolism toward hydrogen production for needed electrons
proteins and energy instead of being used in competing pathways
More efficient catalysts with higher turnover rates
Simple and reliable production systems allowing higher photosynthetic
efficiencies and the use of optimal production conditions
Efficient mechanisms and systems to separate produced hydrogen from other
gases
Cheaper components of the overall system
Investigation of the effect of pH level on growth rate and hydrogen evolution
Production of other carbon-containing energy carriers such as ethanol
butanol and isoprene
Improvements of the photobioreactor design
Up-scaling of photobioreactor (from present active surface of 200 x 600 mm)
Improvement of operating stability (from present about gt100 hours)
Improvement of PAR utilisation efficiency from the present 4 to gt10
Cost reduction towards a hydrogen production price of 4 US$ per kg
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Further metabolic and genetic engineering of strains
Reduction of reactive oxygen species (ROS) which are detrimental to cell
growth
Development of biocompatible catalyst systems that are not toxic to bacteria
Development of ROS-resistant variants of bacteria
Development of hybrid systems compatible with the intermittent nature of the
solar energy source
Development of strains for CO2 reduction at low CO2 concentrations
Metabolic engineering of strains to facilitate the production of a large variety of
chemicals polymers and fuels
Enhance (product) inhibitor tolerance of strains
Further optimisation of operating conditions (eg T pH NADH concentration
ES ratio) for high CO2 conversion and increased formic acid yields
Integration of enzymes into the hydrogen evolving part of ldquobionic leafrdquo devices
Mitigation of bio-toxicity at systems level
Improvements of ldquobionic leafrdquo device design
Up-scaling of ldquobionic leafrdquo devices
Improvement of operating stability (from present about gt100 hours)
Improvement of CO2 reduction energy efficiency towards gt10
Cost reduction of the production of formic acids and other chemicals
polymers and fuels
97
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Increased understanding of surface chemistry at electrolyte-absorber
interfaces
Further improvement of functionalization to achieve higher stabilities without
the need for protective layers
Reduction of defects acting as recombination centres or points of attack for
(photo)corrosion
Reduction of pinhole formation leading to reduced mechanical stability of the
Rh catalyst
Reduction of the amount of rare and expensive catalysts by the use of core-
shell catalyst nanoparticles with a core of an earth-abundant material
Reduction of material needed as substrate by employment of lift-off
techniques or nanostructures
Deposition of highly efficient III-V tandem absorber structures on (widely
available and cheaper) Si substrates
Development of III-V nanowire configurations promising advantages with
respect to materials use optoelectronic properties and enhanced reactive
surface area
Reduction of charge carrier losses at interfaces
Reduction of catalyst and substrate material costs
Reduction of costs for III-V tandem absorbers
Development of concentrator configurations for the III-V based
photoelectrochemical devices
Improvement of device stability from present gt40 hours towards the long-term
stability goal of gt500 hours
Improvement of the STH production efficiencies from the present 14 to
gt17
Cost reduction towards a hydrogen production price of 4 US$ per kg
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Improvements of the light absorption and carrier-separation efficiency
(currently still at lt60) in BiVO4
Better utilization of the solar spectrum by BiVO4 especially for wavelengths
close to the band edge (eg by plasmonic- andor resonance-enhanced
optical absorption)
Further development of novel water-oxidation catalysts based on for example
cobalt- and iron oxyhydroxide-based materials
Further development of the distributed n+ndashn homojunction concept for
improving carrier separation in high-donor density photoelectrode material
Improvement of the stability and avoidance of mass transport and light
scattering problems in devices based on nanoporous materials and DSSC
(Dye Sensitised Solar Cells)
Further development of Pulsed Laser Deposition (PLD) for (multi-layered)
WO3 and BiVO4 photoanodes
Although the near-neutral pH of the electrolyte solution ensures that the BiVO4
is photochemically stable proton transport is markedly slower than in strongly
alkaline or acidic electrolytes
Design of new device architectures that efficiently manage proton transport
and avoid local pH changes in near-neutral solutions
For an optimal device configuration the evolved gasses need to be
transported away efficiently without the risk of mixing
The platinum counter electrode needs to be replaced by an earth-abundant
alternative such as NiMo(Zn) CoMo or NiFeMo alloys
Improvement of device stability from present several hours towards the long-
term stability goal of 1000 hours
Scaling up systems to square meter range
Improvement of the STH production efficiencies from the present 49 to ~9
Cost reduction towards a hydrogen production price of 4 US$ per kg
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Deep molecular-level understanding of the underlying interfacial charge
transfer dynamics at the SCdye catalyst interface
Novel sensitizer assemblies with long-lived charge-separated states to
Design and construction of functional DS-PECs with dye-sensitised
photoanodes and dye-sensitised photocathodes (tandem DS-PEC structures)
Design and construction of DS-PECs where undesired external bias is not
98
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
enhance quantum efficiencies
Sensitizerndashcatalyst supramolecular assembly approach appears as effective
strategy to facilitate faster intramolecular electron transfer for long-lived
charge-separated states
Optimise the co-adsorption for efficient light-harvesting and charge collection
Organometal halide perovskite compounds as novel class of light harvesters
(for absorber applications in DS-PEC)
Encapsulation of perovskite compounds to prevent the dissolution in aqueous
solutions
Semiconductor quantum dots (QDs) as suitable sensitizers for DS-PEC
Exploration of more efficient OERHER catalysts with low overpotentials
Use of a redox mediator analogous to the tyrosine-histidine pair in PSII to
accelerate dye regeneration and thus achieve an increased charge
separation lifetime
One-dimensional TiO2 nanostructures such as TiO2 nanotubes and nanorods
to improved the charge transport properties and thus charge collection
efficiencies
Exploration of alternative SC oxides with more negative CB energy levels to
match the proton reduction potential
Search for alternative more transparent p-type SCs with slower charge
recombination and high hole mobilities
Further studies on phenomena of photocurrent decay commonly observed in
DS-PECs under illumination with time largely due to the desorption andor
decomposition of the sensitizers andor the catalysts
needed
Design and construction of DS-PECs with enhanced quantum efficiency
(towards 90 IPEC)
Ensure dynamic balance between the two photoelectrodes in order to properly
match the photocurrents
Development of efficient photocathode structures
Ensure long-term durability of molecular components used in DS-PEC devices
Reduce photocurrent decay due to the desorption andor decomposition of the
sensitizers andor the catalysts
Ensure active photosensitizer and catalyst for at least millions of cycles in 20ndash
30 years
Ensure long operating lifetimes (such as achieved for DSC) for stable DS-PEC
devices that incorporate molecular components Future work on developing
robust photosensitizers and catalysts firm immobilization of sensitizercatalyst
assembly onto the surface of SC oxide as well as the integration of the robust
individual components as a whole needs to be addressed
Scaling up systems to square meter range
Improvement of the STH production efficiencies IPCE (incident photon to
electron conversion efficiency) need to be improved from ~25 to gt90
Cost reduction towards a hydrogen production price of 4 US$ per kg
99
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Basic understanding of reaction mechanisms in co-electrolysis of H2O (steam)
and CO2
Basic understanding of dynamics of adsorptiondesorption of gases on
electrodes and gas transfer during co-electrolysis
Basic understanding of material compositions microstructure and operational
conditions
Basic understanding of the relation between SOEC composition and
degradation mechanisms
Development of new improved materials for the electrolyte (eg Sr- and Mg-
doped lanthanum gallate (LSGM) and scandium-stabilized zirconia (Sc- SZ))
Development of new improved materials for the electrodes (eg Sr- and Fe-
doped lanthanumcobaltate (LSCF)Sr-doped lanthanum ferrite (LSF)Co-
and Nb-doped barium ferrite (BCFN) and Sr- and Fe-barium cobaltate
(BSCF) perovskites)
Avoidance of agglomeration of Ni-particles and micro-cracks in Ni-YSZ
hydrogen electrodes
Avoidance of mechanical damages (eg delamination of oxygen electrode) at
electrolyte-electrode interfaces
Reduction of carbon (C) formation during co-electrolysis
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Replacing metallic based electrodes by pure oxides
Studies of long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O (steam) and CO2
Improvement of stability performance (from present ~50 hours towards the
long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Improvement of the co-electrolysis syngas production efficiencies towards
values facilitating the production of competitive synthetic fuels via FT-
processes
Cost reduction towards competitiveness of synthetic fuels with fossil fuels
Electrolysis cells for CO2
valorisation ndash Industry
research
Further research on catalyst development
Investigation of catalyst surface structure (highly reactive surfaces)
Catalyst development for a variety of carbon-based chemicals and fuels
Research on electrolyte composition and performance (dissolved salts current
density)
Research on light-collecting semiconductor grains enveloped by catalysts
Research on materials for CO2 concentration
Careful control of catalyst manufacturing process
Precise control of reaction processes
Development of modules for building facades
Stable operation of lab-scale modules
Stable operation of demonstration facility
Improvement of production efficiencies for carbon-based chemicals and fuels
Cost reduction towards competitiveness of the produced carbon-based
chemicals and fuels
100
54 Coordination of European research
Although RTD cooperation exists between universities research institutions and industry from different
European countries the majority of the activities are performed and funded on a national level Thus at
present the level of cooperation and collaboration on a pan-European level seems to be limited
There are few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7
projects and many research groups that are operating locally and are funded by national governments A low
degree of collaboration among different research groups was reported which results in a duplication of efforts
and a lack of generalized standards Synergies which could potentially boost research in artificial
photosynthesis are being overlooked Creating for example a communication platform to facilitate exchange
among actors could more easily promote the development of knowledge and increase the speed of discovery
and exploitation of new robust (effective and durable) photocatalysts innovative processes and devices etc
Another indicated weakness is the lack of collaboration between the already existing and ongoing projects
The coordination of research at a European level is mainly performed by AMPEA The European Energy
Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials amp Processes for Energy
Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging Technologies Artificial
photosynthesis became the first energy research subfield to be organised within AMPEA The goal of this joint
programme which was launched at the end of 2011 is to set up a thorough and systematic programme of
directed research which by 2020 will have advanced the technology to a point where commercially viable
artificial photosynthetic devices will be under development in partnership with industry
Currently AMPEA does not involve biological AP approaches as its main mission focuses on advanced
materials Therefore opportunities for research cooperation in the field of synthetic biology seem limited in the
short term
Furthermore it was stated that the current effectiveness of AMPEA to coordinate research at a European level
is limited also due to budget constraints and limited direct funding provided to AMPEA
Specifically efforts within AMPEA are currently centred on developing a concise RTD roadmap for AP
technologies in Europe The future implementation of this roadmap will require support on both national and
European levels
Table 55 (below) presents a list of European research collaborations within the investigated AP research
technological development and demonstration (RTD) initiatives
101
Table 55 (European) research cooperation within the investigated AP RTD initiatives
AP RTD Initiatives (European) Research cooperation
Photosynthetic microbial
cell factories based on
cyanobacteria
Initiative implemented by Uppsala University Sweden (within CAP) in cooperation with
Norwegian Institute of Bioeconomy Research (NIBIO)
Existing cooperation between Uppsala University and German car manufacturer VW
Biocatalytic conversion of
CO2 into formic acid ndash
Bio-hybrid systems
Initiative implemented by Wageningen UR Food amp Biobased Research and Wageningen UR
Plant Research International The Netherlands (within BioSolar Cells)
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
III-V semiconductor ndash
Silicon tandem absorber
structures
Initiative implemented by TU Ilmenau the Institute for Solar Fuels at the Helmholtz-Zentrum
Berlin and the Fraunhofer Institute for Solar Energy Systems ISE and the California Institute
of Technology (Caltech)
Existing cooperation between TU Ilmenau and epitaxy technology providers Space Solar
Power GmbH and Aixtron SE
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
Bismuth Vanadate
(BiVO4) - Silicon tandem
absorber structures
Initiative implemented by the Institute for Solar Fuels at the Helmholtz-Zentrum Berlin and
two Departments at Delft University of Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Further RTD was done at Repsol Technology Center from Spain in cooperation with
Catalonia Institute for Energy Research (IREC)
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
Initiative implemented by KTH Royal Institute of Technology Sweden in cooperation with
Dalian University of Technology China (within CAP)
Further RTD at University of Amsterdam (within BioSolar Cells) University of Grenoble
University of Cambridge and EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Existing cooperation between OMV and University of Cambridge
Existing cooperation between Siemens and EPFL
Co-electrolysis of steam
and carbon dioxide in
Solid Oxide Electrolysis
Cells (SOEC)
RTD performed at Technical University of Denmark Imperial College London University of
Sheffield and in previous years by Catalonia Institute for Energy Research (IREC) in
cooperation with Repsol Technology Center from Spain
Electrolysis cells for CO2
valorisation ndash Industry
Research
Initiative implemented by Siemens Corporate Technology (CT) in cooperation with the
University of Lausanne and the University of Bayreuth Germany
55 Industry involvement and industry gaps
Due to the low TRL (TRL 2-4) of present AP technology pathways in the areas of synthetic biology amp hybrid
systems photoelectrocatalysis of water (water splitting) and co-electrolysis the direct involvement of industry
in research and development activities in Europe is currently limited
Furthermore detailed information on industry activities in the AP field is difficult to find also due to issues of
confidentiality According to Cefic (European Chemical Industry Council) AP is regarded as a potentially
promising future technology option by the Councilrsquos members however information on industry involvement is
largely kept confidential
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research including
research in artificial photosynthesis However while companies are participating in local consortia such as
BioSolar Cells there currently seems to be a lack of cooperation between academia and industry at an
international level
102
Industry involvement in the area of synthetic biology amp hybrid systems
There is ongoing cooperation between Uppsala University and the German car manufacturer Volkswagen
within the framework of the European project ldquoPhotoFuelrdquo The project is coordinated by VW and focuses on
the production of butanol using micro-organisms
The European industry end users Volvo and VW are involved in the field of the design and engineering of
photosynthetic microbial cell factories based on cyanobacteria however are not directly involved in the
development of micro-organisms themselves
Furthermore in the USA the company Algenol Biofuels Inc is active in the field and operating a pilot scale
production unit
Industrial partners potentially interested in the development of ldquobionic leavesrdquo include the industry partners of
the Dutch BioSolar Cells programme Currently the coupling of the developed enzymes to the hydrogen-
evolving part of the device (ie the development of a full ldquobionic leafrdquo) is subject to ongoing patent procedures
by researchers of Wageningen UR
Industry involvement in the area of photoelectrocatalysis of water (water splitting)
The processes used for the deposition and processing of the devices based on two-junction tandem absorber
structures namely the metal-organic vapour phase epitaxy (MOCVD) and the in-situ functionalisation of
surfaces are generally scalable to an industrial level Spray pyrolysis processes used for the deposition of
dense thin films of BiVO4 are well-established industrial technologies and thus generally scalable to an
industrial level
Industrial stakeholders potentially interested in the area of direct water splitting with tandem absorber
structures include industry partners active in the field of epitaxy technology (eg producers and technology
providers such as Azur Space Solar Power GmbH and Aixtron SE which have ongoing long-term cooperation
with TU Ilmenau) suppliers of industrial process and specialty gases (eg Linde Group) and chemical
industries involved in catalytic processes (eg BASF Evonik)
Further interested industrial stakeholders include industry partners of the network Hydrogen Europe
(httphydrogeneuropeeu) and the Fuel Cells and Hydrogen Joint Undertaking (FCH JU
httpwwwfcheuropaeu) Hydrogen Europe (formerly known as NEW-IG) is the leading industry association
representing almost 100 companies both large and SMEs working to make hydrogen energy an everyday
reality The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) is a unique public-private partnership
supporting RTD activities in fuel cell and hydrogen energy technologies in Europe
The industry player Repsol from Spain was involved (on a research and development level) in the
development of photoelectrochemical water splitting based on metal oxides (WO3 BiVO4) through its Repsol
Technology Center in Spain in cooperation with the Department of Advanced Materials for Energy Catalonia
Institute for Energy Research (IREC) and the Department of Electronics University of Barcelona (UB) The
focus is currently centred on Pulsed Laser Deposition (PLD) for (multi-layered) WO3 and BiVO4 photoanodes
No full devices for photoelectrochemical water splitting have however yet been reported within this initiative
In the area of dye-sensitised PEC potentially interested industrial partners include the major fuel companies
Shell and Total who are already members of SOFI (Solar Fuels Institute based at Northwestern University)
an international research and innovation organisation with several European members (including the core
member Uppsala University) The Austrian fuel company OMV funds research at the Reisner Lab at the
Department of Chemistry at the University of Cambridge which is involved in both dye and catalyst
development
103
Successful technology transfer has recently been reported by Innovation Exchange Amsterdam (IXA) the
technology transfer office of the University of Amsterdam to the French company PorphyChem Rights were
licensed for the commercialisation of novel molecules for hydrogen generation so-called metalloporphyrins
innovative molecular photosensitizers which enable sustainable sunlight-driven hydrogen production from
water In cooperation with IXA the researchers filed patent applications with the European Patent Office on 26
February 2015 H-C Chen A M Brouwer Photosensitizer Europatent application 2015 EP15156740
The industry player Siemens AG from Germany is funding a project implemented by the Laboratory of
Photonics and Interfaces the Institute of Chemical Sciences and Engineering the School of Basic Sciences
and the Ecole Polytechnique Federale de Lausanne (EPFL) for the development of efficient photosynthesis of
carbon monoxide from CO2 using perovskite photovoltaics
Industry involvement in the area of co-electrolysis
Until today the involvement of industry in the research and development of the co-electrolysis of water and
carbon dioxide in Solid Oxide Electrolysis Cells (SOECs) in Europe is limited
Activities (on a research and development level) were performed by the industry player Repsol from Spain
through its Repsol Technology Center in cooperation with the Department of Advanced Materials for Energy at
the Catalonia Institute for Energy Research (IREC) The focus of these efforts is the replacement of metallic-
based electrodes by pure oxides offering advantages for industrial applications of solid oxide electrolysers
Thereby the aim is to ensure suitable H2CO ratios of the produced syngas (ie close to two) fulfilling the
basic requirements for synthetic fuel production
At present the focus of industrial engagement (eg sunfire Audi) for the production of synthetic carbon-based
fuels via concepts using (co)electrolysis and FT-processes favours water electrolysis (for the production of H2)
and the separate addition of CO2 in the FT-process over co-electrolysis of water and carbon dioxide
In April 2015 the company sunfire GmbH announced that it succeeded in producing synthetic diesel from air
water and green electrical energy A demonstration rig for power-to-liquids was inaugurated in November
2014 Recently the plant reached its full operating capacity and now produces synthetic diesel fuel Audi the
German car manufacturer and project partner of sunfire exposed the synthetic diesel to laboratory tests with
the result that the fuel was approved A larger plant needs to be developed in order to proceed towards a
commercial application of this process
An industry-driven approach towards the valorisation of carbon dioxide for the production of carbon-based
chemicals and fuels is implemented by Siemens Corporate Technology (CT) in Munich Germany This work is
implemented within the framework of the Siemens corporate project ldquoCO2toValuerdquo where catalyst
development is performed in cooperation with researchers from the University of Lausanne in Switzerland and
materials scientists at the University of Bayreuth
A small-scale lab unit based on an electrolyser cell is currently in operation at Siemens CT and a large-scale
demonstration facility is planned to be operational in the coming years in order to pave the way towards the
industrial application of this synthetic photosynthesis process for the production of carbon-based chemicals
and fuels to be introduced into the market
104
56 Technology transfer opportunities
The transfer of research to industrial application in artificial photosynthesis remains challenging In order to
attract the attention of the private sector artificial photosynthetic systems have to be cost-effective efficient
and durable The active involvement of industrial parties could help bring research prototypes to
commercialisation This step towards commercialisation requires sufficient critical mass and funding however
which cannot be borne by a single country
In the framework of the assessment of the seven AP technology approaches in the areas of synthetic biology
amp hybrid systems photoelectrocatalysis of water (water splitting) and co-electrolysis a number of ongoing
collaborations between research organisations and the industry as well as future opportunities for technology
transfer have been identified
Technology transfer opportunities in the area of synthetic biology
There are ongoing patent procedures by researchers at Wageningen UR on the coupling of developed
enzymes to the hydrogen-evolving part of the device (ie the development of a full ldquobionic leafrdquo)
Technology transfer opportunities in the area of photoelectrocatalysis of water (water splitting)
There are several patents filed by the researchers of TU Ilmenau and a patent on full device for direct
water splitting with III-V semiconductor based tandem absorber structures is under development
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC) and University of Barcelona (UB)
Successful technology transfer has been achieved by the technology transfer office of the University of
Amsterdam to the French company PorphyChem rights were licensed for the commercialisation of
metalloporphyrins as novel molecules for hydrogen generation which enable sustainable sunlight-driven
hydrogen production from water patent applications have been filed with the European Patent Office
There are technology transfer opportunities between OMV and the University of Cambridge and between
Siemens and EPFL on perovskite PV
Technology transfer opportunities in the area of co-electrolysis
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC)
There are technology transfer opportunities between Siemens and the University of Lausanne as well as
the University of Bayreuth
Table 56 below provides and overview of industry involvement and technology transfer opportunities
105
Table 56 Overview of industry involvement and technology transfer opportunities
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Uppsala University Sweden (within
CAP) in cooperation with Norwegian
Institute of Bioeconomy Research
(NIBIO)
Existing cooperation between Uppsala University
and German car manufacturer VW
Interest by end users Volvo and VW
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Wageningen UR Food amp Biobased
Research and Wageningen UR
Plant Research International The
Netherlands (within BioSolar Cells)
Industry partners of BioSolar Cells
Ongoing patent procedures by researchers of
Wageningen UR on the coupling of the developed
enzymes to the hydrogen evolving part of the
device (ie the development of a full ldquobionic leafrdquo)
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
TU Ilmenau Institute for Solar Fuels
at the Helmholtz-Zentrum Berlin and
the Fraunhofer Institute for Solar
Energy Systems ISE and the
California Institue of Technology
(Caltech)
Existing cooperation between TU Ilmenau and
epitaxy technology providers Space Solar Power
GmbH and Aixtron SE
Interest by suppliers of industrial gases (eg
Linde Group) and chemical industries involved
in catalytic processes (eg BASF Evonik)
Industry partners of network Hydrogen Europe
and the Fuel Cells and Hydrogen Joint
Undertaking (FCH JU)
Several patents filed by researchers of TU
Ilmenau
Patent on full device for direct water splitting with
III-V thin film based tandem absorber structures
under development
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Institute for Solar Fuels at the
Helmholtz-Zentrum Berlin two
Departments at Delft University of
Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
Further RTD at Repsol Technology
Center from Spain in cooperation
with Catalonia Institute for Energy
Research (IREC) and University of
Barcelona (UB)
RTD by Repsol Technology Center focus is
currently placed on Pulsed Laser Deposition
(PLD) for (multi-layered) WO3 and BiVO4
photoanodes No full devices for
photoelectrochemical water splitting have
however yet been reported
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC) and University of Barcelona (UB)
Dye-sensitised
photoelectrochemical cells -
molecular photocatalysis
KTH Royal Institute of Technology
Sweden in cooperation with Dalian
University of Technology China
Existing cooperation between OMV and
University of Cambridge
Existing cooperation between Siemens and
Successful technology transfer by technology
transfer office of University of Amsterdam to the
French company PorphyChem Rights were
106
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
(within CAP)
Further RTD at University of
Amsterdam (within BioSolar Cells)
University of Grenoble University of
Cambridge and EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
EPFL
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Fuel companies Shell and Total
licensed for the commercialisation of novel
molecules for hydrogen generation so-called
metalloporphyrins innovative molecular
photosensitizers which enable sustainable
sunlight-driven hydrogen production from water
Patent applications filed with the European Patent
Office
Technology transfer opportunities between OMV
and University of Cambridge and between
Siemens and EPFL on perovskite PV
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Technical University of Denmark
Imperial College London University
of Sheffield and Catalonia Institute
for Energy Research (IREC) in
cooperation with Repsol Technology
Center from Spain
RTD by Repsol Technology Center focus is the
replacement of metallic based electrodes by
pure oxides offering advantages for industrial
applications of solid oxide electrolysers
Sunfire and Audi (steam electrolysis and FT-
synthesis)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC)
Electrolysis cells for CO2
valorisation ndash Industry
research
Siemens Corporate Technology (CT)
in cooperation with the University of
Lausanne and the University of
Bayreuth Germany
Industry driven approach towards the
valorisation of carbon dioxide for the production
of carbon-based chemicals and fuels by
Siemens CT
Technology transfer opportunities between
Siemens and University of Lausanne University of
Bayreuth
107
57 Regulatory conditions and societal acceptance
The current very low oil prices as well as the low carbon price (ie the fee that must be paid for the right to
emit CO2 into the atmosphere) are hindering the market uptake of the low carbon AP-based production of
chemicals polymers and fuels (carbon-based fuels as well as hydrogen) In addition until today carbon
benefits are only monetised in the energy sector and not for the production of eg low carbon chemicals
Furthermore direct market incentives for solar fuels may be an opportunity for the future development of AP
technologies In addition investments made towards the establishment of a European infrastructure for
hydrogen storage and handling may be beneficial for the future development of AP technologies
Advancements in artificial photosynthesis have the potential to radically transform how societies convert and
use energy However their successful development hinges not only on technical breakthroughs but also on
the acceptance and adoption by energy users
It is therefore important to learn from experiences with other energy technologies (eg PV wind energy
nuclear energy biofuels) and thoroughly involve all societal actors in a discussion on the potential benefits
and drawbacks of the emerging technology already during the very early stages of development
Specifically barriers to social acceptance and issues causing public concern need to be addressed in an open
dialogue and potential measures mitigating concerns need to be discussed and implemented (where
possible) It needs to be kept in mind that the majority of the public is largely unaware of AP technologies
The following main topics are subject to public concern with respect to present AP technology pathways in the
areas of synthetic biology amp hybrid systems photoelectrocatalysis of water (water splitting) and co-
electrolysis
The use of genetic engineering and Genetically Modified Organisms (GMO) mainly for synthetic biology
approaches
The use of toxic materials for the production of AP devices which concerns all pathways
The use of rare and expensive raw materials for catalysts and absorber materials also for all pathways
Land use requirements for large-scale deployment of AP technology and land use competition with other
renewable energy options such as PV solar thermal applications and bioenergybiofuels
High societal costs involved in the development of AP technologies (efficiency and competitiveness of AP
technologies)
The importance of societal dialogue within the future development of AP technologies is widely acknowledged
within several national initiatives in Europe Initiatives on public involvement are implemented within the Dutch
BioSolar Cells programme and by the German National Academy of Science and Engineering (acatech)
109
6 Development roadmap
61 Context
611 General situation and conditions for the development of AP
Current energy technologies are unlikely to be sufficient to attain EU ndash and other international ndash long term
targets for the share of renewable energy sources in overall energy supplies beyond 2020 There is therefore
a strategic interest in supporting efforts to develop new energy technologies (and improve existing ones) and
to raise their competitiveness ndash eg in terms of costs efficiency and resource use ndash vis-agrave-vis those that are
currently available Thus from an energy policy perspective the motivation for accelerating the industrial
implementation of AP technologies arises from their potential to expand the available portfolio of competitive
sustainable energy sources thereby contributing to the continuation of the transition away from fossil fuels At
the same time from the perspective of growth and job creation developing and demonstrating the viability and
readiness for industrial deployment of AP technologies can be viewed as part of a wider industrial policy to
develop an internationally competitive European renewable energy technology industry
Processes based on AP have been identified as having the potential to deliver sustainable alternatives to
conventional fuels AP-based lsquowater-splittingrsquo processes may be used for the production of hydrogen or in
combination with lsquocarbon reductionrsquo for the production of carbon-based fuels (lsquosolar fuelsrsquo) and other higher
order carbon-based compounds However although AP technologies show great potential and despite the
significant progress in research in the AP field made in recent years there is still a significant way to go before
AP technologies are ready for industrial implementation
AP covers several technology pathways that are being developed in parallel and which are all at a low overall
level of technology readiness The individual processes sub-systems and components within the different
pathways are however at varying levels of maturity Consequently it is difficult to foresee the eventual
production efficiency costs and material requirements that could characterise future AP-based systems when
implemented on an industrial scale Moreover while it is possible that some AP technologies may end up
competing with each other complementarities and synergies may arise from AP technology development
activities that are currently being conducted largely in isolation from each other
To date application of AP has only been undertaken in small scale in laboratory conditions and the feasibility
of commercial industrial-scale deployment of AP systems has yet to be demonstrated Assuming that this can
be achieved at cost levels that enable AP-based products to be competitive in the marketplace commercial
implementation may raise some more practical issues for example in relation to land-use water availability
and other possible environmental or social concerns that have not as yet been fully explored
To appreciate the possible future role of AP technologies also requires consideration of other developments
shaping the energy supply and technology landscape Although by definition AP is concerned with the direct
conversion of solar energy into fuel technologies for specific processes developed within the context of AP
may eventually be linked to other renewable energy technologies for example if they are combined with
electricity generated from photovoltaics (PV) or other renewable sources such as wind energy Similarly the
production of lsquosolar fuelsrsquo using AP systems requires a source of carbon which may come in the form of CO2
from ambient air or alternatively by linking AP to carbon capture (and storage) systems90
90
See for example DG Research (2015) ldquoProceedings of the scoping workshop Transforming CO2 into value for a rejuvenated European economy Brussels 26th March 2015rdquo
110
Prospects for the future industrial implementation of AP technologies will not only depend on the lsquopushrsquo
provided by technological developments but will also depend on market lsquopullrsquo factors Not least the
commercial viability of fuels produced using AP technologies (and other renewable energy sources) will be
strongly influenced by price developments for other fuels particularly oil Current low oil and carbon
(emissions) prices must be taken into consideration as factors potentially hindering the market uptake of low
carbon AP-based production of chemicals polymers and fuels (including hydrogen) both now and in the
future
The overall market potential of solar fuels will also depend on public policy developments for example in
terms of regulatory frameworks and incentives affecting demand levels and costsprices of renewable energy
sources Similarly a concerted policy framework targeted towards promotion of a lsquohydrogen economyrsquo may
lead to a shift in emphasis for AP technology development towards hydrogen production (lsquowater splittingrsquo) ndash
already the more advanced area of AP research ndash and away from solar fuels Certainly until a higher
technology readiness level of AP is attained care should be taken to ensure that regulatory measures ndash
whether at European and national levels ndash do not impinge upon or hinder developments along the different AP
pathways
Finally in order to truly accelerate the industrial implementation of AP social acceptance and adoption of the
new technology by energy users must be acquired As it stands the majority of the public is largely unaware
of the development and significance of AP while those who are voice concerns about genetic engineering the
use of toxic materials the use of rare and expensive raw materials and the high societal costs involved in the
development along all technology pathways
612 Situation of the European AP research and technology base
Europersquos scientific communities form more than 60 of the 150 or so research groups on AP worldwide
boasting well-educated researchers and a diverse range of scientists - an interdisciplinary approach being
crucial for scientific advancement within this highly innovative field Together these groups cover all of the
identified existing technological pathways along which the advancement of AP might accelerate thus
increasing the likelihood of cooperation between European scientists with possible breakthroughs on any
given path
Significant improvements are still needed with respect to cost-efficiency lifetimedurability energy efficiency
and resource use for all existing AP technologies and progress is being made in addressing these knowledge
and technology gaps Yet while this technological development making strides along multiple pathways
simultaneously shows a considerable amount of potential the scientific community alone cannot accelerate
the development of the industrial implementation of AP Aiding the development from a currently low
technology readiness level and eventually commercialising AP will involve a host of enabling factors
including those of the financial structural regulatory and social nature
As it stands currently European investment into AP technologies falls short of the amounts being dedicated in
a number of non-European countries and it could be argued is rather short-term if not short-sighted Further
stifling the potential of these technologies is the fact ndash significant considering most European research activity
into AP operates at a national level (only one of the six consortia in Europe being pan-European) ndash that both
national research plans and their funding are fragmented lacking a necessary integrated approach Adding to
this fragmentation there appears to be a lack of cooperation between research groups and academia on the
one hand and between academia and industry on the other This suggests that there are some structural
barriers impeding the speed and success of the development and eventual commercialisation of AP in
Europe
111
Accelerating the development of AP requires bringing the best and brightest to the forefront of the research
being carried out in the field which would in turn involve a conscious effort to boost collaboration of the top
contributors across Europe - such an effort has been the cluster of several FP7 projects the good example of
which may well serve as a foundation on which to build in the future Once the divide between research
groups and academia has been breached and the technological advancement of AP technologies has been
given the push needed to be able to climb higher up the TRL scale interest from and in turn collaboration with
the industry should rise
62 Roadmap overview
The assessment of the existing lsquostate of the artrsquo undertaken for this study reveals that AP technologies are in
general currently at relatively low levels of technology readiness levels91
There are many outstanding gaps in
fundamental knowledge and technology that must be addressed before AP can attain the level of development
necessary for industrial scale implementation Moreover there is not as yet any compelling evidence to
suggest that any particular AP pathway or sub-approach therein can currently be identified as clearly lsquomore
promisingrsquo than another Given this situation it seems appropriate at least for the time being to adopt an
lsquoopenrsquo approach to possible support measures for AP-related research efforts which does not single out and
prioritise any specific AP pathway or sub-approach This conclusion corresponds to the broad consensus view
expressed by participants at the workshop on lsquoArtificial Photosynthesis in Horizon 2020rsquo held in May 2016
Notwithstanding the above assessment if AP is to establish a role in the overall portfolio of energy sources
then the longer-term objective must be to develop competitive and sustainable AP technologies that can be
implemented at an industrial scale Thus a technology development roadmap for AP must support the
transition from fundamental research and laboratory-based validation through to demonstration at a
commercial or near commercial scale and ultimately industrial replication within the market Upscaling of
technologies and integration of processes in a complete lsquovalue chainrsquo ie from light harvesting through to
solar fuel (and other AP-based products) will require greater levels of investment and inevitably will imply
making choices on which technology options to prioritise As the general aim (of the roadmap) is to accelerate
industrial implementation these choices should reflect market opportunities for commercial application of AP
technologies while bearing in mind the overarching policy objectives of increasing the share of renewable
energy sources in overall energy supplies
621 Knowledge and technology development
Following from the above in terms of knowledge and technology development activities the outline roadmap
for support for the development of AP technologies consists of three phases as illustrated in Figure 61 and
described in more detail in the following sub-sections
91
Although the situation of with respect to different process varies most are assessed to be only at TRL 3 or 4 (ie corresponding to lsquoexperimental proof of conceptrsquo or lsquotechnology validated in labrsquo)
112
Figure 61 General development roadmap visualisation
Phase 1 Phase 3Phase 2
Regional MS amp EU
Regional MS EU amp Private
Private amp EU
Private (companies)
FUNDINGSOURCE
TRL 9Industrial
Implementation
TRL 6-8Demonstrator
Projects
Pilot ProjectsTRL 3-6
TRL 1-3Fundamental
Research
RampDampI ACTIVITIES
2017 2025 2035
113
In the following description for convenience the timeline for activities is addressed in three distinct phases It
should be noted however that some AP technologies are more advanced than others and that they
accordingly could already be at or close to readiness for pilot projects (addressed under Phase 2)
Accordingly some laboratory-based validation (TRL 4) and lsquorelevant environmentrsquo validation projects (TRL 5)
may be envisaged within Phase 1 of the Roadmap Conversely as all fundamental knowledge and technology
issues will be not be solved within the 5-7 year time horizon foreseen for Phase 1 the need to support such
development through smaller scale research projects can be expected to continue into Phase 2 of the
Roadmap and possibly beyond
Furthermore in addition to support for fundamental knowledge and technology development the Roadmap
foresees the need to integrate lsquosupporting and accompanying activitiesrsquo (see Section 622) These activities
should run in parallel to the support for knowledge and technology development with initial activities starting
within Phase 1 of the Roadmap and continuing throughout the entire period of the Roadmap It may be
appropriate that some of the suggested activity areas are addressed as part of the proposed Networking
action (Action 2) and Coordinating action (Action 5)
Phase 1 - Time horizon short term (from now to year 5-7)
This phase will target the continuation of early stage research on AP technologies in parallel with initiation of
the process of scaling-up from laboratory based bench-scale projects towards pilot scale projects (ie to
validate whether bench scale projects are viable at a pilot scale) In keeping with the general status of AP
knowledge and technology development the scope of support during this phase should remain lsquoopenrsquo to all
existing (and potential) AP technology pathways and sub-options therein Such an approach should allow for
continued long-term advances in underpinning rsquogenericrsquo scientific knowledge that may lead to a breakthrough
in terms of newnovel approaches for AP while at the same time pushing forward towards addressing
technology challenges across the broad spectrum of AP pathwaysapproaches Notwithstanding this lsquoopenrsquo
approach eventual support may be directed towards specific topics that have been identified as areas where
additional effort is required to address existing knowledge and technology gaps
Under Phase 1 possible EU funding support should a priori be directed towards multiple small scale projects
(eg euro 3-5 million) that can complement existing regional and national programmes (and existing related EU-
level support)
Phase 1 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 1)
Recommendation Support for multiple small AP research projects
Objective To address outstanding gaps in fundamental knowledge and technology relating to AP
Rationale There are many remaining outstanding gaps in AP-relevant fundamental knowledge and
technology that must be addressed before AP systems can attain the level of development
necessary for industrial scale implementation This requires continued efforts dealing with
fundamental knowledge aspects of AP processes together with development of necessary
technology for the application of AP
Resources needed Project funding indicative cost circa euro 3-5 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact Strengthen diversify and accelerate knowledge and technology development for
processesdevices for AP-based production of hydrogen (water splitting) and carbon-based lsquosolar
fuelsrsquo
Priority
High
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
114
Recommendations to support knowledge and technology development (Action 2)
Recommendation Support for enhanced networking for AP research and technology development
Objective To improve information exchange cooperation and collaboration so as to increase efficiency and
accelerate AP-relevant knowledge and technology development towards industrial scale
implementation
Rationale AP research and technology development requires expertise across multiple and diverse
scientific areas both theoretical and applied Notwithstanding existing efforts to support and
enhance European AP research networks (eg AMPEA and precursors) AP research efforts in
the EU are fragmented being to a large extent organised and funded at national levels Further
development of EU-wide (and globally integrated) network(s) would promote coordination and
cooperation of research efforts within the AP field and in related fields addressing scientific
issues of common interest This action ndash offering secure funding for networking activities at a
pan-European level ndash should raise collaboration and increase synergies that potentially are being
currently overlooked
The broader international dimension of AP research and technology development could also be
addressed under this action In particular to develop instruments to facilitate research
partnerships beyond the EU (eg with US Japan Canada etc)
Resources needed Network funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact By providing a platform for knowledge exchange the speed of discovery and exploitation of
knowledge and technology developments should be accelerated both within the research
community and with industry
Priority
Medium
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
Recommendations to support knowledge and technology development (Action 3)
Recommendation AP Inducement Prize
Objective To provide additional stimulus for research technology development and innovation in the field
of AP while also raising awareness amongst the public and other stakeholders
Rationale The inducement prize would a priori target ldquoproof of conceptrdquo of AP at a bench-scale that meet
eligibility and award criteria set for the prize Experience suggests that lsquoinducement prizersquo
schemes can be particularly effective in situations corresponding to those of AP (ie where there
are a number of competing emergent technologies in the TRL 2-4 range that can potentially
deliver similar outcomes) The prize should provide an incentive for researchers to accelerate AP
RampD efforts and also potentially extend interest beyond the current AP research base to a wider
range of potential researchersinnovators
Resources needed Financial prize circa euro3 million
Prize organisation etc euro03 million
Actors involved Funding sources EU possible national (MS) contribution
Potential prize recipients Research and technology development institutions and (possibly)
industry
Expected impact Increased research intensity and wider participation resulting in turn to sooner than otherwise
demonstration of bench-scale AP devices This should provide for an earlier transition from
laboratory based research towards pilot projects
Priority
Medium
Suggested date of implementation92
Short (Phase 1)
92
Based on views gathered by the study there appears to be a general consensus that 3-4 years could be sufficient for the inducement prize contest timeframe Extending the timeframe for a longer period risks prize fatigue where contestants lose sight of the original prize aim and interest can start to wane
115
Phase 1 - Milestones
The scope of knowledge and technology development activities envisaged under Phase 1 is potentially very
broad as it covers multiple lsquopathwaysrsquo and a wide array of challengesissues ranging from general to highly
specific These concern each of the main AP steps (eg light harvesting charge separation water splitting
and fuel production) and range from materials issues device design and supporting activities such as process
modelling In general terms key criteria for evaluating overall progress towards the ultimate objective of
commercial implementation will revolve around factors such as efficiency of conversion of light into solar fuels
alongside the durability and potential cost-effectiveness of AP systems Shorter-term targets (lsquomilestonesrsquo)
could be set for minimum performance levels in terms of conversion efficiency (eg 10 conversion of solar
energy to hydrogen or to carbon-based fuels) although given the variation in progress across AP pathways
variable efficiency targets for individual pathways would seem appropriate
However if the purpose of the milestone is to mark the point of transition from Phase 1 to Phase 2 of the
Roadmap then a pragmatic milestone may be defined in terms of the development of an AP devicesystem
able to produce a lsquouseablersquo quantity of solar fuel in laboratory conditions sufficient to warrant further
development towards a pilot projectplant (Phase 2) In this regard it may make sense to a greater or lesser
degree to align the milestones for Phase 1 to the award criteria retained for the proposed inducement prize
Phase 2 - Time horizon medium term (from year 5-7 to year 10-12)
This phase will focus on reinforcing the implementation of pilot scale projects while initiating the process of
scaling up to a demonstration scale The scope of eventual support should focus on a limited number of
projects for the most promising AP technologies in order to demonstrate their viability at a pilot scale In this
context public (EU) funding support should be directed towards a limited number of medium scale projects At
the same time there should be encouragement of private sector participation in technology development
projects
Phase 2 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 4)
Recommendation Support for AP pilot projects
Objective To develop AP devices and integrated systems moving from laboratory scale up to an
(industrial) relevant scale of production This should enable comparative assessment of different
AP technology approaches at a production scale permitting industrial actors to make a
meaningful assessment of their potential viability for commercial deployment Equally these
projects should serve to identify (priority) areas where additional knowledge and technology
development is required in order to achieve industrial scale implementation
Rationale To reach industrial implementation of AP the feasibility of upscaling from laboratory conditions to
those approaching actual operational conditions needs to be demonstrated Accordingly pilot
projects under this Action item should provide for the testing and evaluation of AP devices to
assess and demonstrate the feasibility of reaching necessary characteristics (eg efficiency
levelstargets durabilitylife-cycle cost effectiveness) for commercial application for the
production of solar fuels The implementation of flexible pilot plants with open access to
researchers and companies should support (accelerated) development of manufacturing
capabilities for AP devices and scaling-up of AP production processes and product supply
Resources needed Project funding indicative cost circa euro 5-10 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Strengthen and accelerate knowledge and technology development for processesdevices for
AP-based production of hydrogen (water splitting) and carbon-based lsquosolar fuelsrsquo
Priority
High
Suggested date of implementation
Medium (Phase 2)
116
Recommendations to support knowledge and technology development (Action 5)
Recommendation Support for AP coordination
Objective To enhance efficiency (and effectiveness) of AP research efforts and more broadly to raise
coordination in the fields of solar fuels and energy technology development
Rationale There is a general need to ensure that research budgets are used effectively and to avoid
duplication of research effort In the context of AP there is a need to identify lsquomost promisingrsquo
technologies and set common priorities accordingly Moving to a common European AP
technology development strategy will require inter alia alignment of national research efforts in
the EU and (possible) cooperation at a broader international level Equally with the aim of
accelerating industrial implementation of AP there is a need to ensure cooperation and
coordination between research and technology development activities among the lsquoresearch
communityrsquo and industry
Resources needed Networkcoordination funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Improved coordination of AP research activities at European level (and possibly international
level) and improved priority setting to address knowledge and technology gaps for AP-based
processes and products
Priority
High
Suggested date of implementation
Medium (Phase 2) with possibility to extend implementation over
long term
Phase 2 - Milestones
The purpose of the AP pilot projects proposed under Phase 2 is inter alia to develop AP production
devicessystems operating at a sufficient scale to assess their potential viability for commercial deployment
Thus AP devicessystems developed within the pilot projects should attain sufficient performance levels and
fulfil basic operational and other characteristics (eg conversion efficiency lifetimedurability
sustainabilityresource use and cost-effectiveness) that are sufficient to attract the potential interest of private
sector (industry) investors Specific milestones for AP pilot projects may therefore be set in terms of multiple
target technical performance requirements but the overarching target lsquomilestonersquo for pilot projects will relate to
the overall assessment of their potential economic (commercial) viability conditional on further technological
developments (including engineering) and subject to their potential to comply with sustainability and other
social requirements
As a bottom line in terms of marking the point of transition from Phase 2 to Phase 3 of the Roadmap the test
for a lsquosuccessfulrsquo pilot project will be reflected in developing technology solutions able to attract private
investors willing to commit to their next stage of development either through a demonstration project (Phase
3) or directly to industrial implementation (lsquoearlyrsquo commercial projects)
Phase 3 - Time horizon long term (from year 10-12 to year 15-17)
This phase will focus of the development of ndash one or more ndash demonstration projects to assess the viability of
AP technologies at an industrial scale and facilitating the transfer of AP-based production systems from
demonstration stage into industrial production for lsquofirstrsquo markets The scope of eventual support should focus
on the AP technologies identified as most viable for commercialindustrial application However demonstration
level products should be led by the private sector ndash reflecting the need to assess commercial viability of
technologies ndash with co-funding provided by the public sector ndash reflecting the risk and large financial burden of
investments in such projects
117
Phase 3 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 6)
Recommendation Support for AP demonstrator projects
Objective To develop one or more demonstrator projects to assess the viability of AP technologies at a
close-to industrial scale (ie the project should be of a sufficient size to serve as a platform and
facilitating the transfer of AP-based production systems from demonstration stage into industrial
production for lsquofirstrsquo markets)
Rationale The demonstration project(s) provide a lsquostepping stonersquo between pilot projects and industrial
implementation The projects should not only provide validation of AP devices and systems but
also allow for developing and evaluating the integration of the full AP value chain93
By
demonstration the (commercial) viability of AP the project(s) should promote full industrial
investments that might otherwise be discouraged by the high cost and risk94
At the same time
beyond addressing technological and operational issues the demonstration projects should
address all other aspects ndash eg societalpolitical environmentalsustainability
economiccommercialfinancial legalregulatory geographic etc ndash necessary to evaluate how
AP based production of solar fuels could be implemented in practice
Resources needed To be determined
[Indicative budget envelope circa euro10-20 million per individual project However required funding
will depend on size and ambition of the project and may significantly exceed this amount]
Actors involved Funding sources Industry with EU support
Funding recipients Research and technology development institutions industry
Expected impact The projects should both build investor confidence in the commercial application of AP-based
solar fuel technologies and raise public confidence including in terms of safety and reliability
Priority
Medium
Suggested date of implementation
Long (Phase 3)
Phase 3 - Milestones
Given that the primary purpose of the demonstrator projects is to assess the viability of AP technologies at a
close-to industrial scale an initial milestone for such projects would be for the plants to be operational and to
be able to produce solar fuels in commercially significant volumes Ultimately the target lsquomilestonersquo will be to
produce solar fuels that are cost-competitive under actual market conditions and commercial requirements
while complying with other key requirements (eg safety societal acceptance etc)
622 Supporting and accompanying activities
The technological development of AP will throughout its various phases be guided by regulatory and market
measures as well as the degree of social acceptance In order to help secure favourable conditions for the
development and eventual commercialisation of AP technologies support will need to be provided from a very
early stage onwards within both of these spheres The prices of competing fuels and carbon emissions may
need to be regulated as well as incentives affecting the demand for renewable energy sources introduced
while the breadth of technological development regarding AP should not be hindered by regulation within the
current phase of research nor research into an eventual shift to a lsquohydrogen economyrsquo be put on the back
burner Thorough involvement of all societal actors in education and open debate regarding the potential
benefits and drawbacks of AP technologies as well as barriers to social acceptance and issues raising public
concern is also required At the same time the economic and commercial aspects of AP production
technologies and AP-produced solar fuels need to be understood including in terms of the development of
successful business models and the competitiveness of European industry in the field of AP and renewable
energy more generally
93
Where this covers the whole AP supplyvalue chain from upstream supply (eg materials components etc) to downstream demand (markets)
94 For example high cost resulting from accelerated investments to scale-up to industrial scale and high-risk profile resulting from uncertainty over which AP technologies may prove most successful together with uncertainty over operating costs and future market prices and demand for solar fuels etc These factors may otherwise discourage investments in (initial) full scale projects unless some public support is provided
118
There is potentially a wide range of themes ndash beyond purely technological and operational aspects ndash which
require to be better understood and which may be addressed through supporting and accompanying activities
including the following (non-exhaustive) topics
Industry engagement and technology transfer As far as can be ascertained the engagement of
industry in the field of AP technologies has to date been limited although because of its commercial
sensitivity it is difficult to obtain a clear picture of industrycompaniesrsquo interest in AP Nonetheless there is
a general view that a greater engagement of the industry would be beneficial for the development of AP
technologies and will become increasingly important as technologies reach higher TRLs and move closer
to commercial implementation An active involvement of industrial players in cooperative research projects
could facilitate the transfer of technology from the research community to industry (or vice versa) thereby
helping speed up the evolution from research prototypes and pilots to commercial implementation
Intellectual property protection To ensure future development and industrial application European
intellectual property in the area of AP should be adequately protected through patents At the same time
worldwide developments in AP-related patent-protected technologies should be taken into consideration
to ensure that Europe avoids potentially damaging dependences on non-European technologies
Regulatory conditions and support measures As a minimum AP technologies and products entering
the market should face a legal and regulatory environment that does not discriminate against their use and
provides a level playing field compared to other energyfuel types Beyond this there may be a public
policy justification (eg reflecting positive externalities of AP) for creating a specifically favourable
regulatory and legal framework to encourage the take-up and diffusion of AP technologies and products
At the same time other actions for example AP project financing support may be implemented to support
the industryrsquos AP investments these may be both for production investments but also for downstream
users faced by high switching costs (eg from fossil to solar fuels)
Societal aspects and safety AP technologies may potentially raise a number of public concerns that
need to be understood and addressed These may relate to safety aspects of the production storage
distribution and consumption of AP-based products for example there may be concern over the use of
genetically modified organisms (GMOs) in synthetichybrid AP processes Other areas of concern may
arise for example in relation to land use requirements or use of rare materials etc In general both
among the general public and even within the industry there is limited knowledge of AP Accordingly it
may be appropriatenecessary to implement activities to raise public and industry awareness of AP
Market potential relating to the assessment of the potential role and integration of AP energy supply and
demand Here multiple scenarios are possible for example depending on whether advances in AP
technology are targeted towards production of hydrocarbons or of hydrogen The former would require
fewer changes in terms of supporting infrastructure development (eg for fuel storage and distribution) but
is currently lagging behind in terms of AP technological development For the latter future market potential
will depend on the evolution towards a greater adoption of hydrogen-based fuel technologies Better
understanding of the shape and direction of market developments both within the EU and globally will be
important for assessing which AP technology developments offer the best prospects for future industrial
implementation At the same time the sensitivity of future prospects for AP technologies and products to
developments in the costs and market prices of competing (fossil and renewable) fuels should be
assessed
Industry organisation and business development relating to the assessment of future industrial
organisation of AP-technology production including the full supplyvalue chain for solar fuels (ie from
upstream supply of materials components equipment etc through fuel production to downstream market
supply including storage and distribution) Such an assessment will be required to better understand the
potential position and opportunities for the European industry in the area of AP which should also take
account of the business models and strategies for European players within the market
119
The aforementioned topics illustrate the diversity of the dimensions surrounding AP that require to be better
understood In a first instance more detailed economic legalregulatory social and other analyses of these
topics is warranted In turn this may lead to the formulation of more concrete policies and actions to develop
appropriate regulatory frameworks and to shape other market and business conditions in order to ensure a
supportive environment for the development and implementation of AP technologies and products
121
7 References
(1) Wilker M B Shinopoulos K E Brown K A Mulder D W King P W Dukovic G Journal of the
American Chemical Society 2014 136 4316
(2) Tachibana Y Vayssieres L Durrant J R Nature Photonics 2012 6 511
(3) Agency I E 2015
(4) Maeda K Domen K The Journal of Physical Chemistry Letters 2010 1 2655
(5) Ni M Leung M K Leung D Y International Journal of Hydrogen Energy 2008 33 2337
(6) Utschig L M Soltau S R Tiede D M Curr Opin Chem Biol 2015 25 1
(7) Chen L Chen F Xia C Energy amp Environmental Science 2014 7 4018
(8) Carmo M Fritz D L Mergel J Stolten D International Journal of Hydrogen Energy 2013 38 4901
(9) Fukuzumi S Curr Opin Chem Biol 2015 25 18
(10) Pinaud B A Benck J D Seitz L C Forman A J Chen Z Deutsch T G James B D Baum
K N Baum G N Ardo S Energy amp Environmental Science 2013 6 1983
(11) Ursua A Gandia L M Sanchis P Proceedings of the IEEE 2012 100 410
(12) Nelson D L Lehninger A L Cox M M Lehninger principles of biochemistry Macmillan 2008
(13) Alberts B Johnson A Lewis J Raff M Roberts K Walter P Classic textbook now in its 5th
Edition 2010
(14) Magnuson A Anderlund M Johansson O Lindblad P Lomoth R Polivka T Ott S Stensjouml K
Styring S Sundstroumlm V Hammarstroumlm L Accounts of Chemical Research 2009 42 1899
(15) Smolentsev G Sundstroumlm V Coordination Chemistry Reviews 2015 304 117
(16) Hammarstrom L Hammes-Schiffer S Accounts of chemical research 2009 42 1859
(17) Barber J Chemical Society Reviews 2009 38 185
(18) Gust D Moore T A Moore A L Faraday discussions 2012 155 9
(19) Centi G Perathoner S ChemSusChem 2010 3 195
(20) Hansen J Ruedy R Sato M Lo K Reviews of Geophysics 2010 48
(21) Pearson P N Palmer M R Nature 2000 406 695
(22) Faunce T A Lubitz W Rutherford A B MacFarlane D Moore G F Yang P Nocera D G
Moore T A Gregory D H Fukuzumi S Energy amp Environmental Science 2013 6 695
(23) Gorka M Schartner J van der Est A Rogner M Golbeck J H Biochemistry 2014 53 2295
(24) Gust D Moore T A Moore A L Accounts of chemical research 2009 42 1890
(25) Armaroli N Balzani V Angew Chem Int Ed Engl 2007 46 52
(26) House R L Iha N Y M Coppo R L Alibabaei L Sherman B D Kang P Brennaman M K
Hoertz P G Meyer T J Journal of Photochemistry and Photobiology C Photochemistry Reviews 2015 25 32
(27) Utschig L M Silver S C Mulfort K L Tiede D M Journal of the American Chemical Society 2011
133 16334
(28) Listorti A Durrant J Barber J Nature materials 2009 8 929
(29) Styring S Faraday discussions 2012 155 357
(30) Walter M G Warren E L McKone J R Boettcher S W Mi Q Santori E A Lewis N S
Chemical reviews 2010 110 6446
(31) Lewis N S Science 2016 351 aad1920
(32) Concepcion J J House R L Papanikolas J M Meyer T J Proceedings of the National Academy
of Sciences 2012 109 15560
(33) Barber J Tran P D Journal of The Royal Society Interface 2013 10 20120984
(34) Gersten S W Samuels G J Meyer T J Journal of the American Chemical Society 1982 104
4029
(35) Gust D Moore T A Moore A L Accounts of Chemical Research 2001 34 40
(36) Kalyanasundaram K Graetzel M Current opinion in Biotechnology 2010 21 298
(37) Wen F Li C Accounts of chemical research 2013 46 2355
(38) McCrory C C Jung S Ferrer I M Chatman S M Peters J C Jaramillo T F Journal of the
American Chemical Society 2015 137 4347
(39) Alenazey F Alyousef Y Almisned O Almutairi G Ghouse M Montinaro D Ghigliazza F
International Journal of Hydrogen Energy 2015 40 10274
(40) Asthana S Samanta C Bhaumik A Banerjee B Voolapalli R K Saha B Journal of Catalysis
2016 334 89
(41) Ihara M Nishihara H Yoon K S Lenz O Friedrich B Nakamoto H Kojima K Honma D
Kamachi T Okura I Photochemistry and photobiology 2006 82 676
122
(42) Ihara M Nakamoto H Kamachi T Okura I Maedal M Photochemistry and photobiology 2006 82
1677
(43) Fukuzumi S Yamada Y Suenobu T Ohkubo K Kotani H Energy amp Environmental Science 2011
4 2754
(44) Vignais P M Billoud B Meyer J FEMS microbiology reviews 2001 25 455
(45) Utschig L M Dimitrijevic N M Poluektov O G Chemerisov S D Mulfort K L Tiede D M The
Journal of Physical Chemistry Letters 2011 2 236
(46) Prince R C Kheshgi H S Critical reviews in microbiology 2005 31 19
(47) Brown K A Wilker M B Boehm M Dukovic G King P W Journal of the American Chemical
Society 2012 134 5627
(48) Lubner C E Applegate A M Knoumlrzer P Ganago A Bryant D A Happe T Golbeck J H
Proceedings of the National Academy of Sciences 2011 108 20988
(49) Iwuchukwu I J Vaughn M Myers N ONeill H Frymier P Bruce B D Nature nanotechnology
2010 5 73
(50) Yacoby I Pochekailov S Toporik H Ghirardi M L King P W Zhang S Proceedings of the
National Academy of Sciences 2011 108 9396
(51) Silver S C Niklas J Du P Poluektov O G Tiede D M Utschig L M Journal of the American
Chemical Society 2013 135 13246
(52) Grimme R A Lubner C E Bryant D A Golbeck J H Journal of the American Chemical Society
2008 130 6308
(53) Rumpel S Siebel J F Faregraves C Duan J Reijerse E Happe T Lubitz W Winkler M Energy amp
Environmental Science 2014 7 3296
(54) Volgusheva A Styring S Mamedov F Proceedings of the National Academy of Sciences 2013 110
7223
(55) Rozendal R A Jeremiasse A W Hamelers H V Buisman C J Environmental Science amp
Technology 2007 42 629
(56) Clauwaert P Toledo R Ha D v d Crab R Verstraete W Hu H Udert K Rabaey K Water
Science and Technology 2008 57 575
(57) Bajracharya S ter Heijne A Benetton X D Vanbroekhoven K Buisman C J Strik D P Pant
D Bioresource technology 2015 195 14
(58) Li M Canniffe D P Jackson P J Davison P A FitzGerald S Dickman M J Burgess J G
Hunter C N Huang W E The ISME journal 2012 6 875
(59) Zhang D Zhao Y He Y Wang Y Zhao Y Zheng Y Wei X Zhang L Li Y Jin T ACS
synthetic biology 2012 1 274
(60) Blankenship R E Tiede D M Barber J Brudvig G W Fleming G Ghirardi M Gunner M
Junge W Kramer D M Melis A science 2011 332 805
(61) Fujishima A Honda K Nature 1972 238 37
(62) James B D Baum G N Perez J Baum K N Square O V DOE report 2009
(63) Hanna M Nozik A Journal of Applied Physics 2006 100 074510
(64) Ross R T Hsiao T L Journal of Applied Physics 1977 48 4783
(65) Khaselev O Turner J A Science 1998 280 425
(66) Wang X Maeda K Chen X Takanabe K Domen K Hou Y Fu X Antonietti M Journal of the
American Chemical Society 2009 131 1680
(67) Kanan M W Nocera D G Science 2008 321 1072
(68) Brillet J Yum J-H Cornuz M Hisatomi T Solarska R Augustynski J Graetzel M Sivula K
Nature Photonics 2012 6 824
(69) Kim J H Kaneko H Minegishi T Kubota J Domen K Lee J S ChemSusChem 2016 9 61
(70) Gao L Cui Y Wang J Cavalli A Standing A Vu T T Verheijen M A Haverkort J E
Bakkers E P Notten P H Nano letters 2014 14 3715
(71) Standing A Assali S Gao L Verheijen M A van Dam D Cui Y Notten P H Haverkort J E
Bakkers E P Nature communications 2015 6
(72) Gao L Cui Y Vervuurt R H van Dam D van Veldhoven R P Hofmann J P Bol A A
Haverkort J E Notten P H Bakkers E P Advanced Functional Materials 2015
(73) Smolyakov G A Osinski M A Google Patents 2011
(74) Herrera A S Google Patents 2013
(75) Joo O S Jung K D Min B K Kim S H Oh J W Google Patents 2008
(76) Google Patents 2015
(77) Liu J Zhang Y Lu L Wu G Chen W Chemical Communications 2012 48 8826
(78) Li J Wu N Catalysis Science amp Technology 2015 5 1360
(79) Laguna-Bercero M A Journal of Power Sources 2012 203 4
123
(80) Graves C Ebbesen S D Mogensen M Solid State Ionics 2011 192 398
(81) Li W Wang H Shi Y Cai N International journal of hydrogen energy 2013 38 11104
(82) Fu Q Mabilat C Zahid M Brisse A Gautier L Energy amp Environmental Science 2010 3 1382
(83) Graves C Ebbesen S D Mogensen M Lackner K S Renewable and Sustainable Energy Reviews
2011 15 1
(84) Christopher K Dimitrios R Energy amp Environmental Science 2012 5 6640
(85) Sun X Chen M Jensen S H Ebbesen S D Graves C Mogensen M international journal of
hydrogen energy 2012 37 17101
(86) Ivy J Summary of electrolytic hydrogen production milestone completion report National Renewable
Energy Lab Golden CO (US) 2004
(87) Haering C Roosen A Schichl H Schnoumlller M Solid State Ionics 2005 176 261
(88) Mahmood A Bano S Yu J H Lee K-H Energy 2015 90 Part 1 344
(89) Jakobsson N B FRIIS P C BOslashGILD H J Google Patents 2014
(90) Stoots C M OBrien J E Herring J S Lessing P A Hawkes G L Hartvigsen J J Google
Patents 2011
(91) JABBAR M HOslashGH J Stamate E BONANOS N Google Patents 2013
[Ca
talo
gu
e n
um
be
r]
KI-N
A-2
7-9
87-E
N-N
KI-N
A-2
7-9
87-E
N-N
EUROPEAN COMMISSION
Directorate-General for Directorate-General for Research amp Innovation
20164960
2016 EUR 27987 EN
Artificial Photosynthesis Potential and Reality
Final
Authors Olivier Chartier Paul Baker Barbara Pia Oberč Hanneke de Jong Anastasia Yagafarova (Ecorys) Peter Styring and Jordan Bye (Sheffield University) Rainer Janssen (WIP Renewable Energies) Achim Raschka and Michael Carus (nova Institut) Stavroula Evangelopoulou Georgios Zazias Apostolis Petropoulos Prof Pantelis Capros (E3MLab) Paul Zakkour (Carbon Counts)
November 2016
LEGAL NOTICE
The information and views set out in this report are those of the author(s) and do not necessarily reflect the
official opinion of the Commission The Commission does not guarantee the accuracy of the data included in
this study Neither the Commission nor any person acting on the Commissionrsquos behalf may be held
responsible for the use which may be made of the information contained therein
More information on the European Union is available on the Internet (httpwwweuropaeu)
Luxembourg Publications Office of the European Union 2016
Catalogue number KI-NA-27-987-EN-N
ISBN 978-92-79-59752-7
ISSN 1831-9424
Doi 102777410231
copy European Union 2016
Reproduction is authorised provided the source is acknowledged
Printed in the Belgium
Europe Direct is a service to help you find answers
to your questions about the European Union
Freephone number ()
00 800 6 7 8 9 10 11
() The information given is free as are most calls (though some operators phone boxes or hotels
may charge you)
5
Abstract
Technologies based on Artificial Photosynthesis (AP) offer the potential to deliver sustainable ldquosolarrdquo
alternatives to fossil fuels which are storable and transportable and can thus respond to the problem of
intermittency of other solar wind and marine energy technologies AP research has intensified over the last
decade pursuing multiple approaches or ldquopathwaysrdquo that each have their own relative advantages and
challenges However as most AP technologies are still at a low level of technology readiness it is currently
not possible to identify those AP pathways and specific technologies offering the greatest promise for future
industrial implementation The study argues accordingly that possible public support should retain an
approach that for the time being keeps Europersquos AP options open The proposed roadmap for support for AP
technology development which could be supported under Horizon 2020 foresees actions to address current
gaps in scientific knowledge and technology capabilities while scaling-up the size of projects through the
implementation of pilot projects and demonstrator projects that can validate the viability of AP technologies at
a commercial scale Europe occupies a frontline position in AP research with 60 of the estimated 150
leading global research groups located in Europe However AP research in Europe is relatively less well-
funded than elsewhere notably in the US and Japan European research efforts are also fragmented driven
by national-level strategies and research programmes Therefore the proposed roadmap integrates actions to
support improved networking and cooperation within Europe and possibly at a wider international-level In
turn improved coordination of national research efforts could be achieved through the elaboration of a
common European AP technology strategy aimed at positioning European industry as a leader in the AP
technology field
7
Executive Summary
Objectives and methodology
Artificial photosynthesis (AP) is considered among the most promising new technologies able to deliver
sustainable alternatives to current fuel supplies often viewed as a potential ldquogame changerrdquo in the fields of
energy conversion and energy production AP can be used to produce hydrogen or carbon-based fuels ndash
collectively referred to as ldquosolar fuelsrdquo ndash that offer an efficient and transportable store of (solar) energy which
can be used as an alternative to fossil fuels and as a feedstock for a wide range of industrial processes
Set against the above background the purpose of this study is to provide a full assessment of the situation of
AP providing answers to the questions Who are the main European and global actors in the field What is
the ldquostate of the artrdquo and what are the main ldquobottlenecksrdquo in scientific and technological development What
are the key economic and technological parameters to accelerate industrial implementation Answers to the
questions provide in turn the basis for formulating recommendations on the pathways to follow and the action
to take to maximise the eventual market penetration and exploitation of AP technologies
To gather information on the direction capacities and challenges of ongoing AP development activities the
study has conducted a comprehensive review of scientific and other literature and implemented a survey of
academics and industrial players This information together with the findings from a series of in-depth
interviews provides the basis for a multi-criteria analysis to identify key bottlenecks for the main AP
technology pathways The study findings were validated at a participatory workshop of leading European AP
researchers which also identified scenarios and sketched out roadmaps for actions to support the future
development of AP technologies over the short to long term
Definition of Artificial Photosynthesis
For the purposes of this study artificial photosynthesis is understood to be a process that aims to mimic
the physical chemistry of natural photosynthesis by absorbing solar energy in the form of photons and
using this energy to generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
Main technology pathways for artificial photosynthesis
It is difficult to precisely define the parameters of AP but there are three main identifiable technology pathways
along which research and development is now advancing
Synthetic biology amp hybrid systems aim to mimic existing biological systems that perform different stages of
photosynthesis (ie light-harvesting charge separation or molecule synthesis) and combine them to produce
specific fuel molecules These technologies are at a very early stage (TRL 1-4) however researchers have
already produced small quantities of hydrogen through the water-splitting reaction and have demonstrated the
reduction of carbon dioxide to methane and acetate Research is also investigating the possibility of using
basic cells (biological) to host biological machinery to generate more complex fuel molecules The long-term
goal is to reliably generate large quantities of fuel molecules combining and converting simple starting
compounds such as H2 and CO2 into a series of different compounds using enzymes and synthetic organic
and inorganic catalysts
8
Photoelectrocatalysis combines and integrates photovoltaic (PV) technologies ndash ie semiconductor materials
able to generate electric current from sunlight ndash with water electrolysis in a photoelectrochemical cell (PEC) or
suspensions of photoactive nanoparticles thereby enabling solar energy to be used to produce hydrogen (and
oxygen) via a water-splitting reaction PV technologies are already deployed commercially and are producing
power on a megawatt scale (TRL 7-8) however PECs to perform photoelectrocatalysis are as yet at a
relatively low stage of development (TRL 2-4) The main challenges facing this technology involve developing
materials that have high solar-to-hydrogen (STH) efficiencies are cheap to manufacture (eg use earth-
abundant metals) and are stable for long periods of time
Co-electrolysis uses co-electrolysis of carbon dioxide and water to generate syngas (COH2) by
simultaneously reducing carbon dioxide and water using a high temperature solid oxide cell electrolyser
(SOEC) syngas can then be used to generate simple intermediate compounds that can be used as feedstock
for more complicated chemicals Water electrolysers ndash such as alkaline and polymer electrolyte membrane
(PEM) electrolysers ndash used to convert water into H2 and O2 are mature technologies (TRL 7-8) that have
been commercialised SOECs are at a lower level of development (TRL 3-5) and given their high electricity
requirements current research is focused on increasing their efficiency
Technology pathways for artificial photosynthesis and indicative selection of generated compounds
Source University of Sheffield (PV = Photovoltaics)
AP research in Europe
Research in the AP field ndash bringing together interdisciplinary expertise from biology biochemistry biophysics
and physical chemistry ndash has intensified over the last decade Today more than 150 research groups are
estimated to be active worldwide of which 60 are in Europe1 Interest from industry is growing as well
although it remains limited due to the overall low levels of readiness for commercial application of many AP
technologies
Europe has a diverse community of researchers active in the AP field and covering all the main pathways with
the largest numbers of research groups located in Germany the Netherlands Sweden and the UK The most
significant and only truly pan-European-level research network is AMPEA2 but most networks and consortia
are national Some Member States have set up their own AP research programmes roadmaps and funds and
1 Source study estimates
2 Advance Materials and Processes for Energy Application (AMPEA) which is one of the joint programmes of the Europe nargy Research
alliance (EERA)
9
there has been successful collaboration in several ongoing European-funded FP7 projects Overall however
the level of funding in Europe falls short of that available elsewhere and national research plans (and funding)
seem fragmented and scattered with a short-term focus and lacking an integrated approach with common
research goals and objectives Equally the level of collaboration between academia and industry seems to be
more limited in Europe compared for example to the US or Japan
Relatively few companies are active in the field of AP and they can be counted in the lsquotensrsquo rather than
lsquohundredsrsquo Co-electrolysis is the only area where AP-related technologies are currently commercially viable
while current industry research activities mostly concern photoelectrocatalysis where companies from various
sectors (eg ranging from automotive and electronics to chemicals and oil refining) are involved There is
some industry involvement in synthetic biology amp hybrid systems but it is limited reflecting the early stage of
research activities along this pathway
Main challenges to development and implementation of AP technologies
To form a sustainable and cost-effective part of future European and global energy systems and a source of
high-value and low carbon feedstock chemicals the development of AP technologies must address certain
fundamental requirements
Efficiency in each main step of AP light captureharvesting (eg maximising the percentage of the
spectrum that can be utilised) energy transfer to a reaction centre (eg minimising energy loss during the
transfer) and charge generation and separation to allow the desired chemical reaction to take place (eg
preventing charge recombination)
Durability of the system in terms of the amount of energy that can be produced during the lifetime of an AP
system which is a challenge because of the rapid degradation of some materials under AP system
conditions (eg lack of long-term stability in aqueous conditions or when exposed to sunlight)
Sustainability of material use eg minimising the use of rare and expensive raw materials
To meet these requirements the main AP technology pathways must overcome several gaps in fundamental
knowledge and technology development (see tables) Even if these gaps can be addressed and the feasibility
of commercial- and industrial-scale deployment of AP systems can be demonstrated at a cost level that
enables AP-based products to be competitive in the market place commercial implementation may raise other
practical concerns These may arise in relation to land use water availability and possible environmental or
social concerns which have not yet been fully explored
Synthetic biology amp hybrid systems
Knowledge gaps Technology gaps
Develop molecular and synthetic biology tools to enable
the engineering of efficient metabolic processes within
microorganisms
Improve metabolic and genetic engineering of
microorganism strains
Improve metabolic engineering of strains to facilitate the
production of a large variety of chemicals polymers and
fuels
Enhance (product) inhibitor tolerance of strains
Minimise losses due to chemical side reactions (ie
competing pathways)
Develop efficient mechanisms and systems to separate
collect and purify products
Improve stability of proteins and enzymes and reduce
degradation
Develop biocompatible catalyst systems not toxic to
micro-organisms
Optimise operating conditions and improve operation
stability (from present about gt100 hours)
Mitigate bio-toxicity and enhance inhibitor tolerance at
systems level
Improve product separation at systems level
Improve photobioreactor designs and up-scaling of
photobioreactors
Integrate enzymes into the hydrogen evolving part of
ldquobionic leafrdquo devices
Improve ldquobionic leafrdquo device designs
Up-scale ldquobionic leafrdquo devices
Improve light energy conversion efficiency (to gt10)
Reduce costs of the production of formic acids and other
chemicals polymers and fuels
10
Photoelectrocatalysis
Knowledge gaps Technology gaps
Increase absorber efficiencies
Increase understanding of surface chemistry at
electrolyte-absorber interfaces incl charge transfer
dynamics at SCdyecatalyst interfaces
Develop novel sensitizer assemblies with long-lived
charge-separated states to enhance quantum
efficiencies
Improve charge transfer from solid to liquid
Increase stability of catalysts in aqueous solutions
develop self-repair catalysts
Develop catalysts with low over-potentials
Reduce required rare and expensive catalysts by core-
shell catalyst nanoparticles with a core of an earth-
abundant material
Develop novel water-oxidation catalysts eg based on
cobalt- and iron oxyhydroxide-based materials
Develop efficient tandem absorber structures on (widely
available and cheaper) Si substrates
Develop nanostructure configurations promising
advantages with respect to materials use optoelectronic
properties and enhanced reactive surface area
Reduce charge carrier losses at interfaces
Reduce catalyst and substrate material costs
Reduce costs for tandem absorbers using silicon-based
structures
Develop concentrator configurations for III-V based
tandem absorber structures
Scale up deposition techniques and device design and
engineering
Improve device stability towards long-term stability goal
of gt1000 hours
Improve the STH production efficiencies (to gt10 for
low-cost material devices)
Reduce costs towards a hydrogen production price of 4
US$ per kg
Co-electrolysis
Knowledge gaps Technology gaps
Basic understanding of reaction mechanisms in co-
electrolysis of H2O (steam) and CO2
Basic understanding of the dynamics of
adsorptiondesorption of gases on electrodes and gas
transfer during co-electrolysis
Basic understanding of material compositions
microstructure and operational conditions
Develop new improved materials for electrolytes and
electrodes
Avoid mechanical damages (eg delamination of
oxygen electrode) at electrolyte-electrode interface
Reduce carbon (C) formation during co-electrolysis
Optimise operation temperature initial fuel composition
and operational voltage to adjust H2CO ratio of the
syngas
Replace metallic based electrodes by pure oxides
Improve long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O
(steam) and CO2
Improved stability performance (from present ~50 hours
towards the long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel
composition and operational voltage to adjust H2CO
ratio of the syngas
Improvement of co-electrolysis syngas production
efficiencies towards values facilitating the production of
competitive synthetic fuels via FT-processes
Cost reduction towards competitiveness of synthetic
fuels with fossil fuels
The AP technology development roadmap
Although AP technologies show great potential and despite significant progress made in recent years there is
still a significant way to go before they are ready for industrial implementation Although some aspects of AP-
based systems are well developed the assessment of the existing lsquostate of the artrsquo shows that AP
technologies are generally at low levels of technology readiness (eg TRL 3-4) Moreover there is not yet
compelling evidence to suggest any AP pathway (or sub-approach therein) is ldquomore promisingrdquo than another
This being the case it seems appropriate to adopt an ldquoopenrdquo approach to possible support measures for AP-
related research efforts in the near term which does not single out and prioritise any specific AP pathway or
approach
Nonetheless if AP technologies are to fulfil their potential it will be necessary to achieve the transition from
fundamental research- and laboratory-based validation to demonstration at commercial of near-commercial
scales this ambition forms the long-term goal for the proposed AP technology development roadmap
11
The roadmap distinguishes 3 phases (see figure below) and corresponding recommendations for specific
actions
Phase 1 (short term) Early stage research and scaling-up to pilot projects
Action 1 Support for multiple small AP research projects to address existing knowledge and technology gaps and to
promote long-term advances in scientific knowledge that may contribute to breakthroughs in novel
approaches for AP and to address technology challenges across the board of current (and potential) AP
pathways and approaches
Action 2 Support for enhanced networking of AP research and technology development to reduce fragmentation and
promote coordination and cooperation of research efforts in the AP and related fields through the support for
pan-European networking activities and promotion of research synergies
Action 3 Inducement prize to provide additional stimulus for research technology development and innovation
through a (financial) prize targeting ldquoproof of conceptrdquo of significant advances in the AP field
Phase 2 (medium term) Pilot project implementation and scaling-up to demonstrator projects
Action 4 Support for AP pilot projects to demonstrate the viability of AP concepts through support for a (limited)
number of pilot plant scale projects of the ldquomost promisingrdquo AP technologies
Action 5 Support for AP coordination to ensure effective use of research budgets and to avoid duplication of research
efforts Moving to a common European AP technology strategy requires inter alia alignment of national
research efforts and cooperation at a broader international level Equally to accelerate industrial
implementation cooperation and coordination of activities among the lsquoresearch communityrsquo and industry
should be promoted
Phase 3 (long term) Demonstrator project implementation
Action 6 Support for AP demonstrator projects to demonstrate the viability of AP technologies through support for one
or more demonstrator projects that facilitate the transfer of AP production systems to industrial production for
ldquofirstrdquo markets while allowing an evaluation of the development and integration of the full AP value chain (ie
from upstream supply of materials and components to downstream markets for AP-based products) The
demonstrator project(s) should also address other aspects (eg societal political environmental economic
and regulatory) necessary to evaluate the practical implementation of AP technologies
NB For convenience the timeline of these actions is presented in 3 distinct phases Some AP technologies are however
more advanced than others and could already be at or close to readiness for pilot projects Conversely certain fundamental
knowledge and technology issues cannot expect to be resolved in the short term Accordingly the different phases as
proposed within the roadmap should not be considered to define a strictly chronological sequencetiming of actions
12
Visualisation of the AP technology development roadmap with illustrative project examples
Source Ecorys
Phase 1 Phase 3Phase 2
TRL 9 Industrial Implementation
TRL 6-8 Demonstrator
TRL 3-6 Pilot Projects
TRL 1-3 Fundamental
2017 2025 2035
Example projects- Research on metabolic and genetic engineering of strains for photosynthetic microbial cell factories
- Research on strains for the production of a variety of chemicals polymers and fuels
- Research on the understanding of surface chemistry at electrolyte-absorber interface in PEC
- Development of novel water-oxidation catalysts for direct water splitting
- Research on improvements of light absorption and carrier separation efficiency in PEC devices
- Research on new materials for electrodes and electrolytes in electrolysis cells
-Research to improve the basic understanding of reaction mechanisms in co-electrolysis (dynamics of adsorptiondesorption of gases gas transfer degradation mechanisms etc)
Example of projects - Improvements of operating stability of microbial cell factories
- Improvements of bionic leaf device design
- Study on long-term durability of molecular components used in DS-PEC devices development of active photosensitizer and catalyst
- Improvement of device stability and STH production efficiencies for direct water-splitting devices at pilot plant scale
- Support the development of lab-scale modules and demonstration facilities of electrolysis cells for CO2 valorisation
- Support the upscaling of cells for efficient co-electrolysis of H2O (steam) and CO2 in Solid Oxide Electrolysis Cells (SOEC)
- Development at a near-commercial scale of demonstrator plant(s) for co-electrolysis
Example of projects- Pilot plant scale of photobioreactors for photosynthetic microbial cell factories
- Pilot plant scale of ldquobionic leafrdquo devices
- Development at a near-commercial scale of demonstrator plant(s) for direct water-splitting devices based on several absorber materials (eg dye-sensitised photo-electrochemical cell (DS-PEC) device silicon-based tandem absorber structures)
13
Supporting activities
Looking beyond the technological and operational aspects of the roadmap the study finds several areas
where actions may be taken to provide a better understanding of the AP field and to accelerate development
and industrial implementation namely
Networking and coordination of research With the exception of the few pan-European initiatives (eg AMPEA
and FP7 projects) the degree of collaboration among research groups is low Networking and coordination
activities (for example through Horizon 2020 Coordination amp Support Action - CSA) would contribute to reduce
duplication of efforts and facilitate exchange among researchers
Industry engagement and technology transfer Engagement of industry in development activities which has so
far been relatively limited will become increasingly important as AP technologies move to higher levels of
readiness for commercial implementation Encouraging active involvement of industrial players in research
projects could ease the transfer of technology from the research community to industry (or vice versa) thereby
helping expedite the evolution from prototypes and pilots to marketable products
Public policy and regulatory conditions To encourage industrial implementation and market penetration AP
technologies and products should face a legal and regulatory environment that offers a ldquolevel playing fieldrdquo
compared to other energyfuel types Beyond this reflecting the sustainability and environmental
characteristics of AP there may be a public policy justification for creating a regulatory and legal framework
and possibly other measures to specifically encourage the adoption and diffusion of AP technologies and
products
Safety concerns and societal acceptance AP technologies could potentially raise a number of public
concerns for example the safety aspects of the production storage distribution and consumption of AP-
based products the use of GMOs in synthetichybrid AP processes the use of rare expensive andor toxic
materials extensive land use requirements etc Such legitimate public concerns need to be identified
understood and properly addressed if AP is to overcome barriers to widespread societal acceptance These
aspects should be an integral part of an overall AP research agenda that provides for open dialogue even
from very early stages of technological development and identifies potential solutions and mitigating
measures
Protection of Intellectual Property To become a successful leading player in the development and industrial
application of AP technologies researchers and industry must be able to adequately protect their intellectual
(industrial) property rights (eg patent protection) without this becoming a barrier to overall technology
development and implementation It will be important to both protect European intellectual property rights
while also follow global developments in AP-related patent-protected technologies thereby ensuring that
Europe has a secure strategic position in the AP field and avoiding potentially damaging dependencies on
non-European technologies
15
Table of contents
Abstract 5
Executive Summary 7
Table of contents 15
1 Introduction 21
2 Scope of the study 23
21 Overview of natural photosynthesis 23
22 Current energy usage and definition of artificial photosynthesis 25
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the study29
231 Synthetic biology amp hybrid systems 31
232 Photoelectrocatalysis of water (water splitting) 31
233 Co-electrolysis 31
3 Assessment of the technological development current status and future perspective 33
31 Synthetic biology amp hybrid systems 34
311 Description of the process 34
312 Current status review of the state of the art 35
313 Future development main challenges 38
32 Photoelectrocatalysis of water (water splitting) 39
321 Description of the process 39
322 Current status review of the state of the art 41
323 Patents 44
324 Future development main challenges 45
33 Co-electrolysis 47
331 Description of the process 47
332 Current status review of the state of the art 52
333 Patents 53
334 Future development main challenges 54
34 Summary 54
4 Mapping research actors 57
41 Main academic actors in Europe 57
411 Main research networkscommunities 57
412 Main research groups (with link to network if any) 59
42 Main academic actors outside Europe 62
421 Main research networkscommunities 62
422 Main research groups (with link to network if any) 64
43 Level of investment 66
431 Research investments in Europe 67
432 Research investments outside Europe 71
44 Strengths and weaknesses 73
441 Strengths and weaknesses of AP research in general 73
442 Strengths and weaknesses of AP research in Europe 74
16
45 Main industrial actors active in AP field 76
451 Industrial context 76
452 Main industrial companies involved in AP 76
453 Companies active in synthetic biology amp hybrid systems 77
454 Companies active in photoelectrocatalysis 79
455 Companies active in co-electrolysis 82
456 Companies active in carbon capture and utilisation 83
457 Assessment of the capabilities of the industry to develop AP technologies 85
46 Summary of results and main observations 86
5 Factors limiting the development of AP technology 91
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges 91
52 Current TRL and future prospects of investigated AP RTD initiatives 95
53 Knowledge and technology gaps of investigated AP RTD initiatives 95
54 Coordination of European research 100
55 Industry involvement and industry gaps 101
56 Technology transfer opportunities 104
57 Regulatory conditions and societal acceptance 107
6 Development roadmap 109
61 Context 109
611 General situation and conditions for the development of AP 109
612 Situation of the European AP research and technology base 110
62 Roadmap overview 111
621 Knowledge and technology development 111
622 Supporting and accompanying activities 117
7 References 121
17
List of figures
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton
gradient NADPH and ATP 24
Figure 22 Worldwide consumption of fuel types by percentage 27
Figure 31 General development and supply chain 33 Figure 32 Diagrammatic representation of a PSI-platinum hybrid system 34
Figure 34 Photoelectrochemical cell capable of water oxidation using solar energy 40
Figure 35 PEC reactor types 42
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting
photoelectrochemical cells 47 Figure 37 Schematic diagram of water electrolysis being conducted in an alkaline electrolyser 48
Figure 38 Schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell 49
Figure 41 Research groups in Artificial Photosynthesis in Europe 62
Figure 42 Research groups active in the field of AP globally 66
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020 69
Figure 44 Hondarsquos sunlight-to-hydrogen station 80
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels 85
Figure 61 General development roadmap visualisation 112
19
List of tables
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
36
Table 01 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the
performance data for each device This table was originally constructed by Ursua et al 201211
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis
cell electrolysers This table was originally constructed by Carmo et al 20138 53
Table 41 Number of research groups and research institutions in European countries 59
Table 42 Number of research groups per research area (technology pathway) 60
Table 43 Number of research groups and research institutions in non-European countries 64
Table 44 Number of research groups per research area (technology pathway) 65
Table 45 Investments in the field of artificial photosynthesis 66
Table 46 EU FP6 and FP7 projects on artificial photosynthesis 68
Table 47 Total EU budget on artificial photosynthesis per technology pathway 68
Table 48 Summary of strengths and weaknesses of research globally 73
Table 49 Summary of strengths and weaknesses of research in Europe 75
Table 410 Overview of the size of the industrial community number of companies per pathway 77
Table 411 Organisations in synthetic biology amp hybrid systems 78
Table 412 Organisations in the field of photoelectrocatalysis 79
Table 413 Companies in co-electrolysis 82
Table 414 Organisations active in carbon capture and utilisation 83
Table 415 Summary of findings size of research community 87
Table 416 Summary of findings size of industrial community 89
21
1 Introduction
To establish a world-class technology and innovation sector that is fit to cope with the challenges up to 2020
and beyond the European Commission initiated an update of its EU energy research and innovation (RampI)
policy leading to the publication of the Communication ldquoTowards an Integrated Strategic Energy Technology
(SET) Plan Accelerating the European Energy System Transformation (C (2015) 6317 final) in September
2015 Under the heading ldquoKeeping Technology Actions Openrdquo the SET Plan Integrated Roadmap states that
ldquothe emergence of new technologies required for the overall transition of the energy sector towards
decarbonisation requires breakthroughs which have to be based on fundamental and generic knowledge at
the international state of artrdquo Artificial Photosynthesis counts among the most promising new technologies and
is often considered as a potential ldquogame changerrdquo technology in the fields of energy conversion and energy
production
The study ldquoAssessment of artificial photosynthesisrdquo has been implemented in the first semester of 2016
against this background the study aims to support future policy developments in the area in particular in the
design of public interventions allowing to fully benefit from the potential offered by the technologies The study
has three specific objectives The first objective is to provide a detailed review of the state of the art of artificial
photosynthesis technologies as well as an inventory of research players from the public and private sector
The second objective is to analyse the factors and parameters influencing the future development of these
technologies The third objective is to provide recommendations for public support measures aimed at
maximising this potential
The structure of the report is as follows Section 2 describes the scope of the study with a review of the
different types of Artificial Photosynthesis Section 3 provides an assessment of the technological
development based on a review of the literature Section 4 maps the main academic and industrial actors
Section 5 analyses the factors limiting the development of Artificial Photosynthesis technologies and a
development roadmap is presented in the Section 6
23
2 Scope of the study
21 Overview of natural photosynthesis
Photosynthetic and heterotrophic organisms exist together in a steady state in the biosphere Photosynthetic
organisms capture solar energy in the form of photons this captured energy is used to produce chemical
energy that the organism uses to form adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide
phosphate (NADPH) ATP and NADPH are then used to generate organic compounds such as carbohydrates
from water and carbon dioxide12
Photosynthesis can be broken down into two processes light-dependant
reactions and carbon-assimilation reactions where the latter are driven by the products of the light reactions
In the light reactions electrons are obtained from water molecules that have been oxidised in a process often
referred to as ldquowater splittingrdquo to form electrons (e-) hydrogen ions (H
+) and molecular oxygen (O2) The
electrons are driven through a series of membrane-bound carrier proteins including cytochromes iron-sulphur
proteins and quinones to produce a proton gradient which is used to generate ATP and NADPH this is
summarised in Figure 21 The carbon-assimilation reactions use NADPH ATP electrons and H+ to reduce
carbon dioxide in a series of enzymatic reactions to generate an array of compounds21213
The light-dependent and carbon assimilation reactions of photosynthesis take place in the chloroplasts of
eukaryotic cells Chloroplasts are intracellular organelles with a non-uniform shape similar to that of
mitochondria They both have inner and outer membranes that enclose an inner compartment which is
permeable to small molecules and ions respectively The thylakoid membrane contains the photosynthetic
pigments and enzyme complexes that carry out the light reactions and ATP synthesis and are on the inside of
the inner membrane Chlorophylls are present in the thylakoid membrane and are responsible for absorbing
solar energy in plants An array of chlorophylls is called a photosystem Chlorophylls are green pigments
consisting of long phytol chains with a polycyclic planar structure similar to the protoporphyr in haemoglobin
at the top of the molecule However instead of a Fe2+
at the centre there is a Mg2+
coordinated by four
nitrogen atoms The phytol chain is esterified to a carboxyl group in ring IV The groups on the edge of the ring
(=CH2 and -CH3) can be exchanged for other groups depending on the organism the chlorophyll is present in
The heterocyclic five-ring system that surrounds Mg2+
has an extended polyene structure with alternating
single and double bonds These compounds strongly absorb in the visible region and have high extinction
coefficients Plants always contain chlorophyll α and chlorophyll β which both absorb green light at slightly
different wavelengths this maximises the amount of light the organism can utilise Chlorophylls bind with
specific proteins and membranes to form light-harvesting complexes (LHCs) In addition to chlorophylls which
are the main pigments in plants there are accessory pigments called carotenoids that absorb photons that
have different wavelengths so more of the spectrum can be utilised When a photon is absorbed by a
chlorophyll an electron in the chromophore portion is raised to a higher energy state called the excited state
When the electron moves back down to its ground state it can release the energy as light or heat In
photosynthesis instead of the energy being released as light or heat it is transferred from the excited
chromophore to a neighbouring chromophore in a process called ldquoexcitation transferrdquo1213
All of the pigment molecules in a photosystem can absorb photons and transfer the energy to other pigments
but only a number of pigments are associated with the photochemical reaction centre (PRC) The excitation
energy can be passed through multiple pigment molecules until it reaches a pigment associated with the PRC
The PRC transduces the excitation energy into chemical energy by passing the excitation energy to a nearby
molecule acting as an electron acceptor This leaves the chlorophyll with a positive charge which is
neutralised by another electron donor the electron acceptor becomes negatively charged In this way
excitation caused by photon absorption causes electric charge separation and starts the oxidation-reduction
chain Light-driven electron transfer in chloroplasts during photosynthesis is carried out by a number of multi-
enzyme complexes in the thylakoid membrane1213
24
Photosynthetic bacteria usually have one or two reaction centres Purple bacteria pass electrons through a
pheophytin which is a chlorophyll without the Mg2+
at the centre of the ring to a quinone Green sulphur
bacteria pass electrons through a quinone to an iron-sulphur centre The photosynthetic machinery in purple
bacteria is made up of 3 basic units a single reaction centre (P870) a cytochrome bc1 electron-transfer
complex (similar to complex III found in mitochondria) and an APT synthase Absorption of a photon drives
electrons through pheophytin and a quinone to the cytochrome bc1 complex following which electrons pass
through this complex to the cytochrome bc1 complex and back to the reaction centre This movement of
electrons generates the energy needed by the cytochrome bc1 complex to pump protons across the
membrane and create the gradient that generates ATP1213
The photosynthetic apparatus of cyanobacteria and plants is more complex than that found in a one-system
bacterium due to them containing two photosystems in the thylakoid membrane Photosystem II acts like the
single photosystem found in purple bacteria It should be noted that the water-splitting reaction occurs at
PSII14
When the reaction centre of photosystem II (P680) is excited electrons are driven through the
cytochrome b6f complex which pumps hydrogen ions across the thylakoid membrane to generate a proton
gradient PSI aids in the reduction of NADP+ to NADPH by absorbing a photon at 700 nm to excite an
electron which is passed through a number of carrier molecules to plastoquinone and then to ferredoxin-
NAPD+ reductase which generates NADPH As previously discussed the proton gradient that has been
generated from transferring the electrons that were excited by the photons is used by ATP synthase to
generate ATP To summarise the light-dependent reactions cause water to split into oxygen electrons and
protons which are used to generate a proton gradient form NAPDH from NAPD+ and generate ATP The
main differences between the two photosystems are the wavelengths of light they absorb and that PSII
conducts water oxidation (while PSI does not) Both absorb photons and both are capable of generating
ATP12-16
In the carbon-assimilation reactions ATP and NADPH are used to reduce (gain electrons) carbon
dioxide to form phosphates starch and sugars as part of the Calvin cycle which takes place in the stroma
this process is also known as carbon fixation1213
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton gradient NADPH and ATP
Theoretically the efficiency of natural photosynthetic systems should be around 26 This is calculated by
knowing the energy content of a glucose molecule is 672 kcal mol-1
To generate a glucose molecule 48
photons with a wavelength of 680 nm are needed which together have an energy of 42 kcal per quantum
mole which is equal to 172 kcal mol-1
672 kcal mol-1
divided by 172 kcal mol-1
makes for 26 efficiency
However in reality an efficiency of less than 2 is usually achieved in optimal conditions17
The efficiency of
natural photosynthetic systems is limited by electron-hole recombination which is when the charge separation
25
process is not successful Even when this process is successful up to half of the energy from the excited state
of the chlorophyll is used2 Energy is also used by the organism to ensure other processes within the cell are
functioning The inefficiencies of natural photosynthesis highlight major areas where researchers are looking
to improve in artificial photosynthetic systems and are discussed over the next sections
Photodamage occurs in photosynthetic systems when solar energy cannot be effectively dissipated as heat or
be used to form photosynthetic products fast enough Upon photon absorption chlorophylls are excited to a
singlet state whereby under normal conditions the chlorophyll molecule will either pass the energy to another
chlorophyll molecule by FRET emit a photon or dissipate the energy as heat High levels of light increase the
amount of photosynthesis occurring as well as the amount of time chlorophylls spend in their singlet state
which increases the risk of chlorophylls forming longer-lived triplet states if the energy is not passed on or
dissipated fast enough Chlorophylls in their triplet state can photosensitise toxic chemicals such as singlet
oxygen which causes photodamage18
Natural photosynthetic systems limit photodamage with a process
called non-photochemical quenching using molecules called carotenoids that quench chlorophyll triplet states
by triplet-triplet energy transfer Carotenoids in their triplet state are low energy and quickly release their
energy through heat production and do not facilitate the production of singlet oxygen1213
This method of
photoprotection has been mimicked in artificial photosynthetic systems to extend their lifetimes and enable
them to work under intense light conditions
22 Current energy usage and definition of artificial photosynthesis
The current demand for energy is primarily met by the combustion of fossil fuel resources in the form of coal
crude oil and natural gas
26
Figure 22 shows that the energy demand has doubled over the last 40 years and it should be noted that this
demand is expected to double again by 205031719
The increased energy demand could be met by increasing
fossil fuel combustion However fossil fuel combustion is not a clean process and releases large amounts of
greenhouse gases such as carbon dioxide carbon monoxide and nitrogen oxides The accumulation of these
greenhouse gases in the atmosphere is increasing the average global temperature damaging the ozone layer
and causing more extreme weather2021
From these studies it is clear that using fossil fuels to meet the future
energy demand could cause irreversible damage to the environment and the human population2223
Due to
this much time money and resources are being dedicated to find clean stable and renewable energy
alternatives to fossil fuels2425
Current candidates include wind power tidal power geothermal power and
solar energy while the viability of nuclear power is currently under discussion due to the radioactive wastes
and potential emergency risks The majority of these technologies are currently expensive to operate
manufacture and maintain and produce rather small amounts of energy due to their low efficiencies This
report will focus on how solar energy is being utilised as a renewable energy source The sun provides
100x1015
watts of solar energy annually across the surface of the earth If this solar energy could be
harnessed with 100 efficiency the current energy demand for one year could be met within an hour In total
only 002 of the total solar energy received by earth over a year would be required161726
27
Figure 22 Worldwide consumption of fuel types by percentage Total fuel consumption was equal to 4667 Mtoe in 1973 and 9301
Mtoe in 2013 and is represented by the size difference of the two charts below The figure was adapted from The 2015 Key
World Energy Statistics report3 Mtoe = million tonnes oil equivalent This figure does not state whether the energy came
from a renewable source
Currently one of the best and most developed methods of utilising solar energy (photons) is by using
photovoltaic cells that absorb photons and generate an electrical current This electrical current can be
instantly used as a source of energy or it can be stored in a wide variety of batteries for later use There are a
number of disadvantages to solely relying on photovoltaics to provide us with all of our energy requirements
which are listed below
Photovoltaics can only be used in areas that have high year-round levels of sunlight
The electrical energy has to be used immediately (unless it is stored)
Batteries used to store electrical energy are currently unable to store large amounts of energy have short
lifetimes and their production generates large amounts of toxic waste materials
To address these disadvantages researchers are looking into ways that solar energy can be stored as
chemical energy instead of inside batteries as electricity This is the point where the research being conducted
begins to draw inspiration from photosynthetic organisms14
Photosynthetic organisms have been capable of
utilising solar energy to generate a multitude of complex molecules for billions of years27
Natural
photosynthetic systems are capable of producing two main fuel types hydrogen and carbon-based fuels
Hydrogen is generated from photon-driven in PSII and carbon-based fuels such as carbohydrates and lipids
are generated from the reduction of carbon dioxide with hydrogen (Calvin cycledark reactions)1628
Hydrogen
and carbon-based fuels are the main fuel types researchers aim to produce using artificial photosynthetic
systems29
Hydrogen is produced by splitting (oxidising) water with solar energy catalysts and water oxygen
is a by-product of water oxidation Hydrogen is the simplest fuel to produce and the majority of the
technologies discussed in this report have already had success producing it It is desirable however for
researchers to generate more complex carbon-based fuels such as carbon monoxide methane methanol and
higher order carbon-based compounds using solar energy carbon dioxide and water because carbon-based
fuels have a higher energy density than hydrogen and are used as our primary energy source It should be
noted that hydrogen does not exist in its molecular form in nature which means that it must be produced by
an energy input Hydrogen is most commonly produced by steam reforming natural gas or fossil fuels such as
propane diesel methanol or ethanol8 These methods produce low purity hydrogen and consume fossil fuels
so they do not relieve any fossil fuel dependencies and they further contribute to environmental concerns
In later sections of this literature review some of the main technologies that utilise artificial photosynthesis to
generate fuel molecules are discussed These technologies offer a potential method by which high purity
hydrogen can be produced by the water-splitting reaction using energy obtained from renewable sources
Hydrogen carbon monoxide and carbon dioxide are important feedstocks for making industrial products such
as fertilisers pharmaceuticals plastics and synthetic liquid fuels With more research it is hoped that it will
soon be possible to produce complex molecules from chemical feedstocks that have been produced using
28
renewable energy Technologies that directly convert solar energy to electrical energy (photovoltaics) have
been commercialised for a number of years and can generate electricity on a megawatt scale at large
facilities Success has also been gained with generating hydrogen with a number of technologies such as
biological hybrid systems photoelectrocatalysis and electrolysers (some sub-technologies in this pathway
have been commercialised and can produce power on a megawatt scale) which will also be discussed in this
literature review Some success has been had with generating these more complicated molecules by artificial
photosynthesis from chemical feedstocks but it should be noted that these technologies are still at an early
research and development stage Using recent literature a definition for artificial photosynthesis was
developed for this study and is provided below
Artificial photosynthesis is a process that aims to mimic the physical chemistry of natural
photosynthesis by absorbing solar energy in the form of photons and using the energy to
generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
This is a broad definition of artificial photosynthesis where the term physical chemistry includes any reaction
or process that takes place during natural photosynthesis The term fuel molecules encompasses the term
solar fuel and can include any molecule that the system has been designed to produce such as molecular
hydrogen hydrocarbons alcohols and carbohydrates Biomimetics refers to a system that aims to mimic a
biological system by including some aspects of a biological system such as photosystems I and II chlorophyll
molecules or the electron transport proteinsmolecules Nanotechnology can refer to systems that use organic
chemistry inorganic chemistry or surfaceinterface chemistry to generate artificial photosynthetic systems
Synthetic biology refers to biological systems that have been genetically engineered to either allow or prevent
a biological process to occur
To date much progress has been made in the development of artificial photosynthetic systems since the
conception of the term22628-35
The most common problems associated with artificial photosynthetic systems
arise from
Low efficiency
Inability to utilise the entire spectrum of photon wavelengths
Inability to efficiently separate the charged species
Most systems use expensive noble metals to conduct the chemistry36
Short device lifetimes
Should these synthetic fuels be produced at a large enough scale for commercial use a new set of problems
would appear associated with how the fuels should be stored and distributed Using artificial photosynthesis to
generate hydrocarbons that are already used as an energy source would require fewer infrastructural changes
than switching to a hydrogen economy Furthermore the production process needs to be easily scalable so
that fuels can be produced in a cost-effective way on a terawatt scale in a manner that can keep up with the
ever-increasing energy demand In the next section several different types of artificial photosynthesis
technologies are introduced that aim to effectively utilise solar energy
29
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the
study
Research and development related to the area of artificial photosynthesis encompass several technological
areas The different pathways for artificial photosynthesis are illustrated in
30
Figure 22 along with some of the compounds that can be generated from these technologies on their own or
by combining them It should be noted that while Figure 23 presents a broad selection of potential compounds
that can be produced the actual number of compounds that could potentially be generated by artificial
photosynthetic systems is limitless
Figure 23 Different routes by which artificial photosynthesis can take place and the products that can be generated by utilising the
different technologies This image was generated by The University of Sheffield PV = Photovoltaics
The efficiency and usefulness of artificial photosynthetic technologies are dependent on how well they can
perform three distinctive steps that are found in natural photosynthetic organisms namely
How efficiently they are able to capture incoming photons (percentage of the spectrum that can be
utilised)
How efficiently the system can transfer the energy to a reaction centre (minimising energy loss during the
transfer)
How well the system can generate and separate charges to allow the desired chemical reaction to take
place (preventing charge recombination)
The complexity of artificial photosynthetic systems occurs when multiple charges have to be separated for a
chemical reaction to occur The production of hydrogen and oxygen from the water-splitting reaction which is
probably the simplest reaction these systems must be capable of still involves the transfer of four electrons
and the generation of more complicated compounds will require even more charge-separation events to occur
The following sections discuss the artificial photosynthetic technologies as depicted in
31
Figure 22 which are synthetic biologyhybrid systems photoelectrochemical catalysis and co-electrolysis
231 Synthetic biology amp hybrid systems
This pathway aims to take existing biological systems that perform different stages of photosynthesis such as
the light-harvesting charge separation or molecule synthesis steps and combine them so they are able to
produce specific fuel molecules These biological molecules can be modified or combined with other biological
molecules or synthetic organicinorganic compounds so that they are able to produce specific fuel molecules
more efficiently It is known that natural photosynthetic systems contain a number of crucial components that
need to be included in synthetic biology and hybrid artificial photosynthetic systems For example they should
contain a light harvester (semiconductor or molecular dye) a reduction co-catalyst (hydrogenase mimic or
noble metal) and an oxidation co-catalyst (photosystem II mimic that is capable of producing molecular oxygen
and hydrogen) It should be noted that these technologies are at a very early stage of development
(laboratory level technology readiness level (TRL 1-4)) and are many years away from being commercialised
Briefly researchers are capable of producing small quantities of hydrogen through the water-splitting reaction
and have demonstrated the reduction of carbon dioxide to methane and acetate Researchers are also
investigating the possibility of using basic cells (biological) to host biological machinery that is capable of
generating more complex fuel molecules The long-term goal of these technologies will be to reliably generate
large quantities of specific fuel molecules from simple starting compounds such as hydrogen and carbon
dioxide which are combined and converted into a series of different compounds using a series of enzymes
and synthetic organic and inorganic catalysts
232 Photoelectrocatalysis of water (water splitting)
This pathway aims to develop efficient photovoltaics and photoelectrochemical catalysts that utilise earth-
abundant metals capable of generating oxygen and hydrogen through the water-splitting reaction38
Photovoltaics can be used to generate electrical energy directly from sunlight Photovoltaicssemiconductors
can be used in photoelectrochemical cells to produce hydrogen from the water-splitting reaction PVs and
PECs are among the most advanced areas of artificial photosynthesis Photovoltaics utilise semiconductor
materials that are capable of directly generating electrical currents (electrical energy) when exposed to certain
wavelengths of light These semiconductors have to be capable of utilising a range of photon wavelengths
efficiently and must have long lifetimes Photovoltaics have been commercialised and are producing power on
a megawatt scale Future developments in this field aim to increase device efficiency and lower the costs
associated with them (TRL 7-8) Photoelectrochemical cells are capable of producing electricity and fuel
molecules when exposed to certain wavelengths of light Fuel molecules such as hydrogen are produced by
electrolysing water (splitting water) which could provide an unlimited source of hydrogen that could be used to
generate power or reduce carbon dioxide Water-splitting cells require semiconductors that are able to support
rapid charge transfer at the semiconductoraqueous interface have long-term stability in aqueous
environments and are capable of utilising a range of photon wavelengths30
233 Co-electrolysis
This pathway provides an alternative method by which water oxidation can be performed Alkaline
electrolysers and polymer electrolyte membrane electrolysers have been mature technologies now for a
number of years and are capable of converting water and electricity to hydrogen and oxygen The co-
electrolysis pathway aims to use carbon dioxide-water co-electrolysis to generate syngas (COH2) which is
produced by simultaneously reducing carbon dioxide and water using high temperature solid oxide cell
electrolysers (SOECs)39
Syngas can be used to generate simple intermediate compounds that can be used
as feedstock for more complicated chemicals used in fertilisers pharmaceuticals plastics and synthetic liquid
fuels Methanol is an example of a simple molecule that can be made from syngas The dehydration of
methanol can be used to generate the cleaner fuel dimethyl ether which is being considered as a future
energy source40
As a technique to produce power co-electrolysis offers a number of advantages over other
techniques such as photovoltaics and wind power in that it is not site-specific and can continuously generate
32
power However these devices require large amounts of electricity to function which affects their operating
costs It is likely that these systems will have their electricity supplied to them by solar or wind power farms in
the near future
33
3 Assessment of the technological development current status and future perspective
This literature review will focus on three technologies (synthetic biologybiological hybrid systems
photovoltaicsphotoelectrochemical cells and co-electrolysis) that are currently using artificial photosynthesis
to generate energy in the form of electricity and fuels The majority of research into these technologies has
focused on improving device efficiencies lifetimes and producing hydrogen The review will conclude with
discussions about the fuels researchers are currently producing potential large-scale facilities to produce the
fuels and finally the potential directions research into artificial photosynthesis could pursue Figure 3 shows a
general development and supply chain for technologies that aim to use artificial photosynthesis to convert
solar energy into power and fuels It should be noted that each technology will have its own set of specific
challenges which will be discussed at the end of each respective section This literature review was
constructed using material from a number of sources such as peer-reviewed journals official reports and
patents that have been filed
Figure 31 General development and supply chain for technologies that aim to use a combination of photovoltaics and
photoelectrochemical cell artificial photosynthetic technologies to convert solar energy into power and fuels
34
31 Synthetic biology amp hybrid systems
311 Description of the process
Artificial photosynthetic systems that utilise synthetic biology aim to modify existing natural photosynthetic
systems at the genetic level or combine them with other biological systems and synthetic compounds to
produce a specific fuel or improve efficiency It should be noted that technologies based on using synthetic
biology and hybrid systems to produce solar fuels are still at the research and development stage (TRL 1-4)
however the use of these systems to produce a limited number of fine chemicals is more advanced with a TRL
3-7 The majority of technologies developed in this pathway have focused on producing hydrogen and only a
limited number of technologies are capable of producing more complex fuel molecules It should also be noted
that most of these systems are only capable of producing small amounts of fuel molecules for a short period of
time Natural photosynthetic systems can be broken down into three distinct processes that these systems
have to mimic light-harvesting energy transfer and charge generationseparation (catalytic reactions)1437
For
these technologies to be successful the systems have to be designed so that they consist of electron donors
and acceptors and attempt to mimic light-driven charge separation2 Generally these technologies aim to
combine biological molecules that have catalytic activity (enzymes such as PSI [NiFe]-hydrogenase and
[FeFe]-hydrogenase) or combine the enzymes with synthetic inorganic and organic compounds9 Examples of
when these systems have been successfully created are discussed below with figures and the TRLs of the
technologies are given after each technology has been discussed
Illustrations
Figure 32 A simplified diagrammatic representation of a PSI-platinum hybrid system that is used to generate H2 can be found below
showing PSI P700 chlorophyll a apoprotein A1 (red) and PSI P700 chlorophyll a apoprotein A2 (blue) The electron provided
by ascorbate is transferred to a cytochrome c6 where a photon excites the electron which is then passed through PSI where
it is transferred to the platinum (Pt) catalyst to generate molecular hydrogen This figure drew inspiration from Fukuzumi
2015 and Gorka et al 20149
35
Figure 33 A diagrammatic representation of a FeFe-hydrogenase I ndash cadmium sulphur (CdS) hybrid system that is used to generate
H2 The faded red structure represents the surface topography of FeFe-hydrogenase I the blue arrows represent the
movement of the electrons through the Fe-S clusters where hydrogen ions are converted to H2 and the yellow structures
represent the CaI capped CdS nanorods The figure was constructed using inspiration from Wilker et al 2014 using the
PBD file 3C8Y and edited using PyMol software12
312 Current status review of the state of the art
The first example of researchers successfully producing light-driven hydrogen from an artificial complex
composed of biological molecules and platinum was achieved by combining the PSI subunit PsaE from
Thermosynechococcus elongtus with an oxygen tolerant [NiFe]-hydrogenase from Ralstonia eutropha H16 to
form a PSI-hydrogenase complex This complex in presence of ascorbate (electron donor) was capable of
light-driven hydrogen production at a rate of 058 microM (mg chlorophyll)-1
h-1
41-43
(TRL 3)
Hydrogenases are enzymes that catalyse the reversible oxidation of molecular hydrogen while platinum is
also capable of reversibly photocatalytically oxidising hydrogen44
Researchers recently showed that when a
platinum nanocluster was attached to a PSI molecule the complex was able to produce hydrogen at a rate of
673 microM (mg chlorophyll)-1
h-1
- the general structure of this complex is highlighted in Figure 323
Systems
based on these original concepts have been optimised to achieve higher hydrogen production efficiencies of
up to 244 microM (mg chlorophyll)-1
h-1
It should also be noted that the electron donor (ascorbate) had to be
present in excess in both cases2345
It should also be noted that these hydrogen production rates are
comparable to those of natural photosynthetic systems which occur at a rate of ca 300 microM (mg chlorophyll)-1
h-1
46
(TRL 3-4)
Researchers recently proposed a model by which hydrogen can be generated using CaI capped CdS
nanorods The authors reported that light is absorbed by the CdS nanorods to excite two electrons which are
then transferred into the CaI cap where the two electrons are used to reduce two protons (H+) and generate
hydrogen (electrons are replaced in CdS by ascorbate) In a recent publication the authors showed that it is
possible to combine the CdSCaI nanorods with [FeFe]-hydrogenase in place of PSI (ascorbate is used as an
electron donor) In this biomimetic system the electrons are transferred to [FeFe]-hydrogenase where they
reduce H+ to hydrogen This system was shown to have a quantum efficiency of 20 be active for up to 4
hours and had a total turnover of 106 hydrogen before activity was lost The loss in activity was found to be
due to the inactivation of the CaI cap at the end of the CdS rod147
36
Figure 3 represents the system and process described above where the blue arrows represent the movement
of electrons from the CdSCaI nanorods to the iron-sulphur clusters in [FeFe]-hydrogenase (TRL 3-4)
Researchers were recently able to produce hydrogen using a PSI-cobaloxime complex when it was
illuminated with natural light Cobaloximes are vitamin B12 mimics capable of catalysing H+ reduction
Cobaloximes offer a number of advantages over hydrogenases in that they are not sensitive to oxygen their
synthesis is relatively simple and they are constructed from relatively cheap materials In this system sodium
ascorbate used a sacrificial electron donor and cytochrome c6 transported the electrons to the PSI-cobaloxime
complex Upon light absorption the electrons were excited and transported through PSI to the bound
molecular catalyst cobaloxime where hydrogen production occurs27
The maximum rate for the photoreduction
of water by this hybrid system was measured to be 170 mol hydrogen (mol PSI)-1
min-1
as was reached within
10 minutes of illumination It should be noted that after 90 minutes hydrogen production levelled off giving a
total turnover of 5200 mol hydrogen mol PSI-1
27
It is thought that the activity of the hybrid decreased due to
the dissociation of cobaloxime from PSI research efforts are currently underway to stabilise the hybrid
system27
This system is of particular merit because the PSI-cobaloxime hybrid is composed of earth-
abundant materials unlike the hybrid systems containing precious metals It should also be noted that there
are multiple molecular catalysts for hydrogen production other than the cobaloximes that can offer improved
stability solubility in water and better activity and have been discussed in a recent review6 (TRL 3-4)
The production of hydrogen at a rate of 2200 plusmn 460 micromol mg Chl-1
h-1
(a faster rate than natural photosynthetic
systems) has recently been demonstrated This was accomplished by generating a hybrid system consisting
of a PSI complex tethered to a [FeFe]-hydrogenase using a 18-octanedithiol nanowire and also crosslinking
cytochrome c6 to the PSI complex This four component system was then placed in a sodium phosphate buffer
containing the electron donor sodium ascorbate at pH 65 and illuminating the sample with natural light48
The
authors also reported results for complexes consisting of different nanowire lengths (3-10 carbons) and a
chain length of 8 carbons was found to give the highest hydrogen production rates this is most likely due to
the chain being long enough to minimise steric hindrance between the two proteins The hybrid system
retained its activity for up to four hours and it should be noted that the decrease in activity was attributed to
depletion of the electron donor (full activity was regained upon replenishing the ascorbate) It should also be
noted that the hybrid system regained its full hydrogen-evolving activity after being stored in anoxic conditions
at room temperature for 100 days48
(TRL 3)
The technologies above are only a few examples of the methods researchers have used to generate hydrogen
from hybrid systems Table 31 below summarises hydrogen production rates by a number of different hybrid
systems that all incorporate PSI into their complex The information in Table 31 was originally summarised by
Utschig et al 20156 All of the technologies in this table have a TRL of 3-4
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
PSI-catalyst system Rate of H2 production
[mol H2 (mol PSI)-1 s
-1]
TON (time hours)
PSI-nanoclusters photoprecipitated long liveda 49
0002 ndc (2000)
PSI-[NiFe]-hydrogenase genetic fusion 41
001 ndc (3)
PSI-nanoclusters photoprecipitated short-liveda 49
013 ndc (2)
PSI-[FeFe]-hydrogenase-PetF in vitro complexb 50
031 ndc (05)
PSI-Ni diphosphinea 51
073 (3)
PSI-[FeFe]-hydrogenase-Fd protein complexb 50
107 ndc (1)
PSI-molecular wire-Pt nanoparticlea 52
11 (12)
PSI-NiApoFd protein deliverya 51
125 (4)
PSI-cobaloximea 27
283 (15)
PSI-Pt nanoparticlea 45
583 (4)
PSI-molecular wire-[FeFe]-hydrogenasea 48
524 ndc (3)
a Redox mediator Cyt c6
b Redox mediator PC
c nd not determined
37
Researchers have generated a hybrid photocatalyst system capable of splitting water to produce hydrogen
and oxygen and capable of reducing carbon dioxide by rational design The system uses a semiconductor as
the light harvester and a biomimetic complex mimicking photosystem I as a molecular catalyst37
This work
highlights that the understanding of artificial photosynthetic systems is increasing as rational design can now
be used to construct biomimetic artificial photosynthetic systems (TRL 2)
Unicellular organisms such as Chlamydomonas reinhardtii are a type of green algae that can produce
hydrogen light-dependently using the enzyme [FeFe]-hydrogenase However hydrogen production rates in
photoactive organisms are limited by a number of physiological constraints This is due to electrons
generated by PSI being used in a number of reactions other than hydrogen production5354
Most photoactive
organisms will contain a form of photosynthetic electron transport ferredoxin (PETF) protein which provides
photosynthetic electrons generated by PSI for a number of metabolic pathways All of these pathways
compete for electrons with [FeFe]-hydrogenase Researchers recently genetically modified the affinity PETF
has for PETF-dependent ferredoxin-NADP+-oxidoreductase (FNR) without comprising the affinity PETF has
for [FeFe]-hydrogenase In this modified system PETF is still able to supply [FeFe]-hydrogenase with
electrons that it used to produce hydrogen but is less able to supply electrons to FNR which means that fewer
carbon dioxide fixation reactions occur Hydrogen production rates increased by nearly 5x in wild type cells
that had modified PETF53
(TRL 3)
Microbial biocathodes consist of an electrode that has electrochemically active microorganisms immobilised
onto its surface which are capable of reducing protons to hydrogen These systems offer a number of
advantages in that the cathode can be constructed from cheap materials and the microorganisms can self-
regenerate55
The first microbial biocathode consisted of three phases (1) acetate and hydrogen are oxidised
at a bioanode that has been inoculated with a mixed culture of electrochemically active microorganisms to
release carbon dioxide (2) only hydrogen is fed into the bioanode (3) the polarity of the cells is reversed
(direction of electron flow) and hydrogen production begins at the cathode55
Initially after the polarity is
reversed methane was produced at the biocathode and not hydrogen (TRL 4)
Bio-catalysed electrolysis is a microbial fuel cell-based technology that is capable of generating hydrogen and
other reduced products from electron donors (acetatewastewater) however these systems require an
external power source56
In this system acetate is oxidised at the anode by microorganisms in the presence of
high concentrations of ammonium and the electrons are transferred to a platinum catalyst (cathode) where
they reduce protons to hydrogen56
(TRL 3)
A recent paper has reported the reduction of carbon dioxide to acetate and methane using a water-splitting
reaction to produce hydrogen and sodium bicarbonate as the carbon source using microbial electrosynthesis
(MES)57
This system used an assembly of graphite felt and a stainless steel cathode This paper is important
because it presents the use of electrode materials derived from earth-abundant elements showcasing them
as particularly suitable for industrial scale-out due to their low cost (TRL 3)
Researchers at the University of Oxford developed a biological tool called ldquoSimCellrdquo A SimCell is a simple
non-replicating cell that has no well-defined function until a plasmid containing DNA coding a specific
function is inserted into the cellrsquos genome The inserted DNA could potentially provide all of the genetic
information needed by the cell to produce the proteins and enzymes required to produce specific fuel
molecules The SimCell has been optimised to be simple so that most of the energy the cell is using will go
towards carrying out the function of the newly inserted gene instead of maintaining numerous intracellular
processes5859
The SimCell could allow researchers to insert genetic information that codes the production of
target fuels thereby greatly increasing the number of potential fuel targets and the efficiency with which they
can be produced It is possible that this technology could be patented once it reaches a higher level of
maturity and a working system is demonstrated (TRL 1)
38
313 Future development main challenges
Synthetic biology amp hybrid artificial photosynthetic systems primarily focus on producing hydrogen however
research focused on the production of hydrocarbons using technologies such as MES is gaining momentum
Although these technologies are currently at the laboratory research and development stage (TRL 1-4) they
are improving quickly At a very small laboratory scale the systems are becoming efficient enough to produce
hydrogen at a rate that is comparable to that which occurs in natural photosynthesis although some
researchers have reported even faster production rates
Synthetic biology amp hybrid systems need to address a number of specific challenges before they can be
considered as commercially viable options for producing solar fuels Below some preconditions and
challenges regarding certain such systems are described
Protein Hybrid Systems
For proteins to be active their primary amino acid sequence must fold and adopt the correctly folded
structure Misfolded proteins can exhibit severely diminished activities
Proteins (and enzymes) are inherently unstable and sensitive to the pH temperature pressure and buffer
components and will often degrade over time which limits their use
Most hydrogenases are sensitive to oxygen so they must be kept under anaerobic conditions
Biological molecules can be produced at a large scale as shown by the biopharmaceutical industry
However the amount of biological molecules needed to produce the amount of fuel required to support
mankind would be huge and has not been calculated
One of the strongest properties of enzymes is that they exhibit a high level of specificity they are able to
produce specific molecules of high purity
Enzymes can be redesigned to give them new or improved functions within different environments60
However modifying protein and enzyme function is not trivial it is often a time-consuming process that
requires thorough understanding of the system although predictive tools for protein engineering are
improving
Enzymes are often very large molecules in which only a small percentage of the amino acid residues are
actively involved in catalysis Researchers could reduce the complexity of biological systems drastically if
they focused on stripping the enzyme down so it contains only the residues and cofactors needed for
catalytic activity on a simplified base framework of amino acids
Microorganisms
In a recent paper researchers investigated how hydrogen production can be enhanced and suppressed in
vitro They state that the main limitations of hydrogen production in microorganisms are the systemrsquos
sensitivity to oxygen and the competition between hydrogenases and NADPH-dependent carbon dioxide
fixation If these issues can be solved the technologies would be closer to commercialisation50
It should be
noted that microorganisms are capable of producing a number of fine chemicals on a commercial scale (these
are often produced in smaller amounts)
Microorganisms are highly complex in that a multitude of chemical reactions must take place so that the
organism can continue to function at the most basic level These extra reactions are major drawbacks if
these organisms are to be used to produce fuel molecules as most of the absorbed energy cannot be
used to produce the fuel molecules
To overcome this problem various aspects of the organismsrsquo genetic information can be modified to
minimise energy loss through side reactions
SimCells are simplified cells in that number of chemical reactions needed to sustain the organism are
minimised this means that more energy can dedicated to fuel production However these technologies
are currently in early stages of research and development and are not close to being produced on an
industrial scale
39
It is likely that fuel-producing microorganisms will have to be capable of expelling the fuel molecules
otherwise the fuel-producing cells will have to be destroyed to obtain the molecules
A major advantage of bacterial systems is that their genetic information can be modified so that they
produce a number of different fuel molecules However this is not a trivial task and the microorganisms
may not be able to survive when large concentrations of the fuel molecules are present
Bacterial cells can survive in a number of harsh conditions and they do not have to be in an ultra-clean
environment
Synthetic biology and hybrid systems face a unique challenge in that these systems are made by or are
genetically modified organisms (GMOs) GMOs are often subject to negative media attention and are often
portrayed and viewed to be unsafe by the public which means that the public may not want their fuel coming
from this source Some of the concerns surrounding the use of GMOs are valid and need to be investigated
One of the main concerns about the use of GMOs pertains to whether the GMO could have a severe effect on
the environment if it managed to migrate into the wild However this issue could be addressed by only using
GMOs that are not able to replicate (ie they are obtained from a secured parent cell) However most of the
concerns the public may have regarding GMOs could be solved by educating about GMOs and providing a
large body of scientific evidence that supports their safety
It should be noted that the authors could find no relevant patents for artificial photosynthetic technologies that
utilise synthetic biology amp hybrid systems
In conclusion synthetic biology amp hybrid systems that produce solar fuels are currently in the laboratory
research and development stage and it is too early to determine whether they would be a commercially viable
option However current research is promising and shows that they could be a valuable part of generating
solar fuels due to their high level of specificity and ability to be reengineered to carry out new and specialised
chemistry
32 Photoelectrocatalysis of water (water splitting)
321 Description of the process
This pathway aims to develop efficient photovoltaics and photoelectrocatalysts that utilise earth-abundant
metals capable of generating oxygen and hydrogen by splitting water38
The water-splitting (water oxidation)
reaction is one of the most advanced areas of artificial photosynthesis These systems that directly produce
fuel molecules from sunlight are currently in the early researchproof-of-concept stage (TRL 2-4) This means
that they are a number of years away from being a commercially viable method to produce synthetic fuels31
Water oxidation involves the removal of 4e- and 4H
+ to generate molecular oxygen (O2) and molecular
hydrogen (H2) In nature water oxidation is carried out by photosystem II in natural photosynthetic systems
The water-splitting reaction has the potential to provide a clean sustainable and abundant source of
hydrogen that could be used as energy or to reduce carbon dioxide to higher order hydrocarbons which is
why a considerable amount of time and money has been spent trying to improve the process
Photovoltaic cells (PVs) also known as solar cells utilise semiconductor materials that are capable of directly
generating electrical currents when exposed to certain wavelengths of light Light absorption by the
semiconductor promotes an electron from the low energy valence band to the higher energy conduction band
This creates an electron-hole pair that can be transported through the electrical device to provide power
Research focusing on PVs has focused on improving their efficiencies Initially efficiencies lt1 were
obtainable but the most recent generation of PVs can achieve efficiencies gt45 Research has shown that
the efficiencies of PVs can be greatly improved by using multi-junction instead of single-junction devices60
Efficiencies of different PV models have increased over the last 40 years this plot is courtesy of the National
Renewable Energy Laboratory Golden CO The most recent PVs have long lifespans (gt20 years) low
40
pollution levels and low operating costs30
However PVs do have some drawbacks in that they are expensive
to manufacture can only be used during the day in areas that receive a lot of sunlight utilise a fraction of the
available spectrum and it is problematic to store the energy in batteries3360
Problems associated with long-
term storage of energy could be overcome by storing the energy in chemical bonds of molecules such as
hydrogen alcohols and hydrocarbons which is why the research in the following section is of importance It
should also be noted that PVs have a TRL of 9 as they have been successfully commercialised and can
provide power on a megawatt scale
Photoelectrochemical cells (PECs) are capable of producing fuel molecules when exposed to certain
wavelengths of light or paired with a semiconductor (PV) Hydrogen can be produced by the water-splitting
reaction Figure 3 shows a schematic diagram of a PEC which is capable of conducting water oxidation in
two separate chambers Currently there are two primary methods by which solar fuels can be generated from
the water-splitting reaction in PECs The first is by direct photoelectrocatalysis at the semiconductor-
electrolyte interface (occurring at a solid-liquid junction) and the second is by coupling the electrochemical
(PEC) reaction directly to a buried p-n junction PV230
Both of these approaches require the generation of a
photovoltage sufficient to split water (gt 123 V)30
Photoelectrodes in PECs must have high surface stability
good electronic properties and suitable light absorption characteristics Water-splitting cells require
semiconductors that are able to support rapid charge transfer at the semiconductoraqueous interface have
long-term stability in aqueous environments and are capable of utilising a range of photon wavelengths30
These functions are obtained by using multi-junction configurations that use p- and n-type semiconductors
with different band gaps and surface-bound electrocatalysts The brief description of PVs has been included
because they are an essential component for a number of systems that photocatalytically split water
Illustration
Figure 34 The illustration below shows a photoelectrochemical cell capable of water oxidation using solar energy consisting of
separated titanium dioxide (TiO2) and platinum (Pt) electrodes Water oxidation occurs at the TiO2 electrode where oxygen
is formed during which process protons (H+) and electrons (e
-) are released H
+ pass through an ion transport membrane to
a compartment containing the Pt electrode where electrons are used to reduce H+ to hydrogen After this hydrogen can be
stored as an energy source or it can be used to reduce carbon dioxide to higher order hydrocarbon compounds
Explanations
According to the National Renewable Energy Laboratory the greatest gains in efficiency have been made with
the multi-junction PV cells The first single-junction GaAs cells developed in the mid-1970s and had
efficiencies of ca 22 (which is better than most of the more recent PV cells that have been developed) The
most recent multi-junction technologies have achieved efficiencies of up to 46 It should also be noted that a
41
greater number of p-n junctions a PV has the greater its efficiency This is because each p-n junction is made
from a different semiconductor material that can absorb light at a different wavelength increasing the amount
of the spectrum that can be utilised PVs based on crystalline silicone cells have shown a slow increase in
efficiency over the last 40 years starting from 14 and increasing up to 276 PVs utilising thin-film
technologies now achieve efficiencies up to 223 Thin-film technologies are a particularly promising branch
of PV due to them being lightweight and the potential to manufacture them by printing which would decrease
their production and installation costs
Figure 3 shows a schematic diagram of a PEC cell that was developed by Honda and Fujishima in 1972 and
was capable of the water-splitting reaction using a TiO2 electrode in tandem with a platinum electrode61
PEC
cells consist of three basic components a semiconductor a reference electrode and an electrolyte The
principles of PEC cell operation are simple a photon is absorbed by the semiconductor (TiO2) material which
causes electron excitation and the excited electrons move to the reference electrode (Pt) through a metal
wire The movement of electrons between the two materials generates a positive charge (holes) at the
semiconductor which combines with electrons in the oxygen molecules of water to form molecular oxygen
and hydrogen ions At the reference electrode the electrons can combine with hydrogen ions to form
molecular hydrogen In this study oxygen was generated at the TiO2 electrode and hydrogen was generated at
the platinum electrode
Since the initial study by Honda and Fujishima researchers have spent much time developing new materials
for anodic and cathodic processes that are capable of carrying out the same process with greater efficiency
and ability to produce more products3061
Currently the cost-effectiveness of using solar energy systems to
generate power and fuels is constricted by the low energy density of sunlight which means low cost materials
need to be developed so that enough sunlight can efficiently be captured Sunlight availability is intermittent
which means that the captured energy needs to be efficiently stored The efficiency of PEC water-splitting
devices is determined by measuring their solar-to-hydrogen (STH) efficiency this is defined as the amount of
chemical energy produced in the form of hydrogen divided by the solar energy input without the use of any
external bias10
322 Current status review of the state of the art
Currently there are two main approaches that are used to photocatalytically split water into oxygen and
hydrogen The first method utilises a single-visible-light photocatalyst (this is essentially a PV) with a narrow
band gap capable of absorbing photons in the visible spectrum has a suitable thermodynamic potential for
water splitting and is stable enough to avoid photocorrosion4 The drawbacks of this system include that it is
only capable of utilising a small region of the spectrum and the collection of oxygen and hydrogen is difficult
due to them being produced in the same region2 The second method uses a two-step mechanism which
utilises two photocatalysts (photoanode and photocathode) in tandem similar to the Z-scheme present in
natural photosynthetic systems2 This setup enables the system to utilise a larger range of visible light
because the free energy required to drive each photocatalyst can be tuned compared to the one-step system
(one photon is needed for each photocatalyst) In this system the oxygen and hydrogen generated via water
oxidation can be separated more efficiently from each other because they are produced at different sites
(oxygen is produced at the anode and hydrogen is produced at the cathode) this also reduces the likelihood
of charge recombination462
This second system is more desirable as the oxygen and hydrogen evolution
sites can be contained in separate compartments62
Theoretical calculations have highlighted that the
maximum efficiency of a single absorber PEC system could reach 29-31 whereas a tandem PEC system
could reach 40-41 further highlighting the advantages of using tandem devices106364
Efficiency calculations
for three different PEC configurations a single photoabsorber system a dual stacked photoabsorber system
and a dual side-by-side photoabsorber system were reported to be 112 228 and 155 respectively
These systems differ in the spatial distribution and number of photoabsorbers which will affect the range of
wavelengths that can be absorbed and therefore the materialsrsquo STH efficiency10
It should be noted that the
practical efficiencies of these devices will often be much lower due to the inefficiencies associated with the
catalysts and reaction overpotentials10
These calculations show that the best way to achieve higher
efficiencies in PEC devices is to use a dual stacked photoabsorber system
42
Recently four PEC reactor types were conceived to represent a range of systems that could be used to
generate hydrogen from solar energy Each system design can be seen in Figure 31062
Types 1 and 2 are
based on relatively simple photoactive nanoparticle suspensions whereas types 3 and 4 are based on more
complex planar arrays a brief discussion of each system is given below It should be noted that quoted STH
efficiencies are optimised values and do not take into account material lifetimes
Figure 35 The figure below shows four PEC reactor types including a (a) Type 1 reactor showing the plastic bags containing the
suspended hydrogen- and oxygen-evolving photoactive particles (b) Type 2 reactor showing the plastic bags containing
separated suspensions of photoactive particles capable of separately evolving hydrogen and oxygen (c) Type 3 reactor
showing a sun-orientated panel containing a layered PEC cell capable of producing hydrogen and oxygen and (d) Type 4
reactor the design of which consists of a similar layered PEC cell to Type 3 with an added parabolic receiver that is able to
concentrate light onto the PEC cell throughout the day These figures were originally constructed by Pinaud et al 201310
Type 1 This reactor has the simplest design It consists of a transparent plastic bag that contains a
suspension of photoactive particles in 01 M potassium hydroxide that are capable of simultaneously
evolving hydrogen and oxygen by the water-splitting reaction Photons at a variety of different wavelengths
are able to penetrate the plastic bag whereas the electrolyte evolved gases and photoactive particles are
held within the bag The authors modelled the photoactive particles as spherical cores coated with
photoanodic and photocathodic particles The authors calculated that this reactor type could achieve a
realistic STH efficiency of 10 however it should be noted that the hydrogen and oxygen evolved in this
system would need to be separated1062
43
Type 2 The design of this reactor is very similar to that of Type 1 in that it consists of photoactive
nanoparticles suspended in an electrolyte contained within clear plastic bags The main difference
between the two systems is that the hydrogen- and oxygen-evolving particles are contained within
separate bags which reduces the need for a gas separation step and increases the safety of the system
However the bag design has to be more complicated in that a redox mediator is required along with a
porous bridge between the hydrogen- and oxygen-evolving bags The STH efficiency of this system was
calculated to be 51062
Type 3 This reactor is composed of a layered planar electrode consisting of multiple photoactive layers
(multi-junction PVsemiconductor) that is submerged within an aqueous solution containing 01 M
potassium hydroxide encased within a clear plastic case Multiple photoactive materials are used so that
more of the solar spectrum can be utilised The anode (oxygen evolution) is at the top of the cell where it
absorbs photons of a certain wavelength and allows others to pass through to the cathode where they are
absorbed into another layer to drive hydrogen evolution Due to the fixed orientation of these cells they
have to have a large surface area to ensure they can absorb the maximum amount of photons1062
Type 4 This reactor is similar to Type 3 in that it consists of a flat PEC cell of a similar design (gas
evolution occurs in a similar manner) The main difference is that a solar tracking concentrator system is
used to focus sunlight onto the PEC cell This means that smaller and more efficient PEC devices can be
used to reduce costs The STH efficiency of this system was calculated to 12-181062
The costs of hydrogen production for a power plant consisting of each reactor type were assessed (it should
be noted that costs for Type 3 and 4 plants were considered to be more accurate due to availability of PV
pricing)10
Type 1 $160 H2kg
Type 2 $320 H2kg
Type 3 $1040 H2kg
Type 4 $400 H2kg
During early work with PEC cells researchers were able to achieve efficiencies of 124 for hydrogen
production over 20 hours using a p-GaInP2(Pt)rsquoTJGaAs electrode However it should be noted that current
density decreased from 120 mAcm2 to 105 mAcm
2 over the course of the experiment which was caused by
damage to the PEC cell65
Therefore although this device was able to achieve high efficiencies its lifetime
was too low
Water oxidation in the presence of a photocatalyst that has been combined with a co-catalyst has been
reported2 The role of the co-catalyst is to provide extra reaction sites and decrease the activation energy for
oxygen and hydrogen evolution Researchers must carefully choose the type of co-catalyst to use this is
because although some noble metal catalysts like platinum and rhodium are good for enhancing hydrogen
production they also catalyse the reverse reaction (convert oxygen and hydrogen back to water)66
To
circumvent this issue transition-metal oxides are often used as co-catalysts instead of noble metals as these
do not catalyse water reformation However these compounds are often more susceptible to degradation
when they are exposed to the reactive environments found in PECs4
The first example of a metal oxide being used to split water into oxygen and hydrogen was carried out by a
dinuclear ruthenium complex (the blue dimer)34
Electrochemical and in situ spectroscopic measurements
were used to measure hydrogen production when platinum and rhodium plates deposited with chromia
(Cr2O3) were used as the water-splitting material4 Coreshell-structured nanoparticles that have a noble metal
or noble metal oxide core and a Cr2O3 shell have been shown to be capable of acting as a co-catalyst for the
water-splitting reaction This presents a mechanism by which noble metals could be used as co-catalysts the
Cr2O3 shell has been shown to supress the water reformation reaction when coated onto palladium and
platinum cores4 Multiple transition metal oxides such as NiOx RuO2 and TiO2 can be used as co-catalysts
when they are treated with appropriate chemicals (TRL 3-4)
44
Researchers recently reported a catalyst that was formed upon the oxidative polarization of an inert indium tin
oxide electrode immersed in a solution containing 100 mM potassium phosphate and 05 mM cobalt (II) ions at
pH 70 Upon initiation of electrolysis at 129 V oxygen production was shown to increase linearly over 12
hours to reach a maximum of 100 microM h-1
(after 12 hours electrolysis was stopped)67
The catalytic activity of
the reaction was also shown to be pH-dependent which suggests that the hydrogen phosphate ion is the
proton acceptor (TRL 3)
In a recent publication a multi-junction design was used to absorb light and provide energy for the water-
splitting reaction Multi-junction PVs are more efficient as they are able to absorb enough solar energy to
provide the free energy for water splitting The researchers developed a device based on an oxide
photoanode (Fe2O3 or WO3) and a dye-sensitized solar cell which performs unassisted water splitting with an
efficiency of up to 31 STH Incoming light was absorbed by the photoanode where the water-splitting
reaction and oxygen evolution takes place Electrons were transported to a platinum cathode where hydrogen
formation occurred68
(TRL 4)
Recently researchers demonstrated water splitting using tandem PEC cells where PtCdSCGSACGSe was
used as the photocathode (hydrogen evolution) and NiOOHFeOOHMoBiVO4 as the photoanode (oxygen
evolution) The cell was able to sustain a stable water-splitting reaction for 2 hours with an STH efficiency of
06769
(TRL 3)
Photochemical hydrogen production by nanowire arrays has been shown to be advantageous to more
traditional system designs because they use less precious material to produce7071
Researchers recently
showed that photoelectrochemical hydrogen production from water was possible using InP nanowire arrays In
these systems the chosen nanowire compound has a layer of silicone oxide (SiO2) deposited onto its surface
and then a co-catalyst deposited onto the surface of Efficiencies of 52 and 64 were obtained when the
InP nanowires were deposited with platinum and MoS3 respectively7072
Silicon is an abundant low-cost
semiconductor commonly used in PV devices and photoelectrochemical hydrogen generation at the
Sielectrolyte interface has been extensively studied for decades Hydrogen is evolved slowly at the
Sielectrolyte interface which has led to research efforts to modify the surfaces with electrocatalysts such as
platinum and ruthenium which are showing good activities and efficiencies71
(TRL 2-3)
323 Patents
Patents have been filed for systems based on nanoparticle suspensions and PECs some of which are
discussed below
A patent was filed in 2012 detailing a suspension of photoactive nanoparticles consisting of metallic cores and
semiconductor photocatalytic shells that can photocatalytically split water to directly obtain hydrogen The
efficient and unassisted photocatalytic splitting of water by the nanoparticles is based on resonant absorption
from surface plasmon in the metal coresemiconductor shell hybrid nanoparticles which can extend the
absorption spectra towards the visible-near infrared range This increases the solar energy conversion
efficiency When the photoactive nanoparticles are used in combination with scintillator nanoparticles the
hybrid photocatalytic nanoparticles can be used to convert nuclear energy into hydrogen73
(TRL 3-4)
A patent was recently filed for a PEC cell consisting of melanin melanin precursors melanin derivatives
melanin variants melanin analogues natural or synthetic pure or mixed with organic or inorganic compounds
metals ions drugs that act as the water electrolyzing material This technology uses solar energy as the sole
or main source of energy to produce hydrogen from water The system integrates a semiconductor material
and a water electrolyser inside a monolithic design that produces hydrogen directly from water using light
between 200 to 900 nm as the main or sole source of energy The technology aims to meet two criteria (i) the
system or light-absorbing compound should generate enough energy for the water-splitting reaction to be
45
completed and (ii) the materials need to be cheap to source and exhibit high stability in water and the reactive
environment The authors claim that all of these requirements can be met by melanin and related compounds
which represents a significant advancement in PEC design The technology can be used to generate
hydrogen oxygen and high energy electrons It can also be used to perform the opposite reaction and
generate water from electrons protons and oxygen and can be coupled to other processes generating a
multiplication effect It can also be used for the reduction of carbon dioxide nitrates and sulphates or others74
(TRL 2-3)
In 2008 a patent was filed describing a PEC system that could produce hydrogen from water The device was
comprised of (i) an electrolytic bath containing an electrode for catalytic oxidation an electrode for catalytic
reduction and an ion separation film disposed between the two electrodes immersed in an aqueous
electrolyte solution and (ii) a photoelectrode positioned outside the electrolytic bath and electrically connected
to the two electrodes This PEC system is characterised by disposing a photoelectrode at a position which
does not contact the electrolyte solution preventing the lowering of the photoelectrode activities and which
maximises hydrogen production efficiency75
(TRL 3)
In 2014 a patent was filed describing an invention that was able to generate hydrogen by
photoelectrocatalytic water splitting The system also incorporated an analysis-detection system The system
was composed of a photoelectrocatalytic water-splitting hydrogen generation device constructed from TiO2
nanorods (water splitting) a platinum cathode and a AgAgCl reference electrode submersed in a 05 M
Na2SO4 solution Results from five tests of the system were reported After the first hour the device produced
17-20 micromolh hydrogen for four hours as determined by the inbuilt detector76
(TRL 3)
324 Future development main challenges
The generation of electricity from solar energy by PVs has been successfully commercialised with the most
recent solar projects being able to produce electricity at a cost of 015 ndash 035 $kWh on a megawatt scale31
Facilities such as the Solar Star Power Station and the Topaz Solar Farm in the USA are examples of facilities
that use PV technologies that are capable of producing electricity (TRL 8-9) These facilities can now be
constructed because the cost of PVs has dramatically decreased and their efficiencies have increased over
the last few years Laboratory research is currently focused on further increasing the efficiency of PVs and
combining these systems with catalysts that are capable of generating higher order hydrocarbon fuels
However the reduction of carbon dioxide to liquid fuels is a complicated multi-electron process still in the
proof-of-concept stage (TRL 2-3) It is also recommended that the new materials PVs are constructed from
should ideally be cheap abundant lightweight flexible and robust If all of these requirements are met the
costs associated with manufacturing PVs as well as transporting installing and maintaining them may
continue to fall
There are a number of general challenges facing PEC technologies (including suspensions of photoactive
nanoparticles and PECs) that are associated with
Effectively designing facilities
Developing methods to store the generated energy
Developing transportation networks to distribute the energy
A major drawback of these facilities is that they can only be used during daylight hours when there is a clear
sky This highlights the importance of being able to store large amounts of energy at these facilities that can
be used outside of daylight hours It has been proposed that the energy generated from these facilities could
be stored in new types of batteries or as chemicals such as hydrogen and hydrocarbons Storing the energy
in the form of hydrocarbons would be particularly useful as these have a much higher energy density than
batteries and hydrogen The infrastructure to store and transport these already exists for them to be used as a
fuel However as previously mentioned the ability to convert hydrogen and carbon dioxide into high order
hydrocarbons using PVs and PECs is still in the proof-of-concept stage10
46
There are also a number of challenges related to the materials used to construct photoactive nanoparticles
and PECs This is particularly problematic because the most useful semiconductors are not stable in water
and the metal oxides that are stable in water often have band gaps that are too large for light absorption1065
There are three main processes that cause electrodes to degrade over long periods of time and inhibit their
activity
The first is corrosion which occurs with all materials over long periods of time
The second is catalyst poisoning which is caused by the introduction of solution impurities and it has
been shown that low concentrations of impurities can have a huge impact on electrode efficiency77
Finally changes to the composition and morphology (structurestructural features) of the electrode can
decrease their efficiency30
As well as exhibiting high stability the materials have to be highly efficient However there is a relationship
between device complexity cost and efficiency Water-splitters using triple-junction amorphous silicon or IIIndashIV
semiconductors have good efficiencies (5-10) but have high costs and device complexities Simpler
approaches using oxide-based semiconductors in a dual-absorber tandem approach have reported STH
conversion efficiencies up to 0368
This highlights the need to find cheaper and efficient semiconductor
materials that can be used for the water-splitting reaction
The US Department of Energy has determined that the price of hydrogen production delivery and dispensing
must reach $2-3 kg-1
before it can compete with current fuels2 It is also important to take into account the
infrastructural changes that would be required if we were to adopt a hydrogen fuel economy To meet the
current power demands of the US with PVs that have an efficiency of 10 a total area of 58000 miles2 would
be required The cost of semiconductors capable of these efficiencies amounts to tens of trillions of dollars
not taking into account the huge costs associated with the required changes to the infrastructure32
These
facilities would only be viable in areas where there is an abundance of sunshine (such as deserts) which also
proposes large fuel transportation issues In the majority of areas the sun is intermittent and only provides
about 6-10 hours of sunshine per day This further highlights the need to be able to store the energy in the
form of chemical bonds that can be used at any time as well as be more easily stored as batteries can only
store a relatively small amount of the energy required and can produce large quantities of toxic materials when
manufactured
It has been calculated that for the water-splitting reaction to provide one third of the energy required by the
human population in 2050 10000 solar plants each covering a 5 km x 5 km area (250000 km2 = 1 of the
Earthrsquos desert area) and with an overall efficiency of 10 would be required Each plant would be capable of
generating ca 570 tonnes of hydrogen from 5100 tonnes of water per day which together could provide up to
33 of the energy needed by mankind in 2050 The hydrogen could be transported directly to on-site
chemical plants where other organic compounds can be manufactured4 Figure 3 shows two diagrams of one
of these sites that could be capable of producing 570 tonnes of hydrogen per day24
The amount of each
material needed to generate methane from hydrogen and carbon dioxide is given in the formula below in
tonnes The US Department of Energy has set a target for hydrogen-producing PEC devices to have an STH
efficiency of 10 and a 5000 hour durability by 201878
120784119815120784 + 119810119822120784 rarr 119810119815120786 + 119822120784
120784(120784120790120787) + 120788120784120789120782 rarr 120784120784120790120782 + 120786120787120788
According to these calculations 6270 tonnes of carbon dioxide would be required by each of these plants per
day to use all of the hydrogen generated to produce 2280 tonnes of methane and 4560 tonnes of oxygen
The amount of carbon dioxide required increases linearly as the hydrocarbon chain length increases The cost
of manufacturing the number of PEC cells required to carry out this amount of water splitting would be in the
tens of trillions of euros taking into account the current costs of the associated technology62
The energy
required to power these facilities would be obtained from renewable sources such as wind wave and PVs
47
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting photoelectrochemical cells H2 generated
on-site could be used to reduce CO2 to higher order hydrocarbon fuel molecules These figures were constructed by Maeda
et al 2010 and Tachibana et al 2012
33 Co-electrolysis
331 Description of the process
Electrolysers capable of conducting the water-splitting reaction have existed for centuries Water electrolysers
are capable of converting water and DC electricity into gaseous hydrogen and oxygen according to the
equation below879
High-pressure (30 bar) water electrolysers have been commercially available since 1951
In 2012 there were at least 13 manufactures that produce low temperature water electrolysers (3 using
polymer electrolyte membranes (PEM) and 3 using alkaline electrolysers)79
Electrolysers that use solid oxide
electrolysers cells (SOECs) under high temperatures were first developed in the 1980s in the HotElly project
Currently SOEC technologies are still in the research and development stage It should also be noted that the
water splitting thermodynamics are more favourable at the higher temperatures used in SOECs as compared
to alkaline electrolysers PEMs and PECs ΔG = 237 kJ mol-1
(123 eV) at ambient temperatures ΔG = 183 kJ
mol-1
(095 eV) at 900 oC
8397980
120784119815120784119822 + 119811119810 rarr 120784119815120784 + 119822120784
Co-electrolysis is a technique that can be used to produce fuel molecules directly from electricity water and
carbon dioxide Interest in the electrolysis of water and carbon dioxide originated in the 1960s where it was
thought that the process could be used to supply oxygen for submarines and spacecraft81
Unlike electrolysis
co-electrolysis aims to simultaneously split water and reduce carbon dioxide to form a mixture of carbon
monoxide (CO) hydrogen and oxygen this process is highlighted in the equation below The term ldquosyngasrdquo
(synthesis gas) refers to a mixture of carbon monoxide and hydrogen and not the oxygen component
Producing fuels by co-electrolysis consists of three main stages carbon dioxide capture syngas synthesis
and storage of the renewable energy as chemical bond energy (hydrogen and hydrocarbon fuels)80
This
chemical reaction is achieved by using high temperature solid oxide cell electolysers3982-84
Co-electrolysis
offers a number of advantages over solar and wind power farms Solar and wind power farms have to be built
in site-specific areas to maximise their power output which limits the number of countries that would be able
to host these technologies (solar power is only viable for countries that have high levels of sun year-round)
Solar and wind power farms are only able to generate power intermittently which makes them unsuited to
coping with sudden large power demands (solar farms can only generate power during daylight hours) It has
been suggested that batteries and thermal fluids could be used to store energy for peak times However
48
these storage methods are currently unable to store large amounts of energy suffer from short lifetimes and
generate large amounts of harmful waste during production531
Technologies capable of co-electrolysing
water and carbon dioxide to syngas and hydrocarbons are at an early stage of development TRL 2-4
119810119822120784 + 119815120784119822 rarr 119810119822 + 119815120784 + 119822120784
It is also important to note that all electrolysers require a large input of electrical energy which would have to
be from renewable sources if this technology is to relieve its dependence on fossil fuels The major cost
associated with solid oxide electrolysis cells (SOEC) comes from the electricity required to operate them and
the feedstock while the cost of the electrolyser material makes up a smaller proportion of the total cost39
If
SOECs were designed to utilise wind and solar energy (PVssemiconductors) to generate the electricity they
require their operating costs would decrease significantly However this also decreases the number of
countries that could host electrolysers as their operation is again dependent on solar and wind energy It
would also be advantageous to incorporate a Fischer-Tropsch process that is capable of generating synthetic
hydrocarbons from the resulting syngas that can be used in the existing infrastructure3985
Syngas can be used to generate simple intermediate compounds that can be used as feedstock for more
complicated chemicals such as fertilisers pharmaceuticals plastics and synthetic liquid fuels Methanol is an
example of a simple molecule that can be made from syngas The dehydration of methanol can be used to
generate the cleaner fuel dimethyl ether which is being considered as a future energy source40
The most
common feedstocks for the production of hydrocarbon fuels are fossil fuels and biomass However it is hoped
that sustainable feedstocks such as carbon dioxide and water can be used to generate syngas which can be
converted into hydrocarbon fuels through Fischer-Tropsch synthesis39
Illustrations
Figure 37 A schematic diagram of water electrolysis being conducted in an alkaline electrolyser (left) and a polymer electrolyte
membrane electrolyser cell (right) to produce hydrogen and oxygen from water and DC electricity This figure was originally
produced by Carmo et al 20138
49
Figure 38 A schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell that produces hydrogen and
oxygen from water and DC electricity the reactions that occur at the electrodes are also shown This figure was adapted
from Meng Ni et al 20085
Explanations
Alkaline water electrolysis has been a mature technology for over 100 years (there were over 400 units in
operation by 1902) They have high efficiencies (47-82) and long lifetimes (15 years)1186
A recent
publication by Ursuacutea et al 2012 compiled a list of the main manufacturers of alkaline water electrolysers which
is shown in Table 3211
A number of advancements have been made regarding alkaline electrolysers over the last few years which
have focused on improving their efficiency to reduce operating costs and have increased the operating
current densities11
Other advancements include
Minimising the space between the electrodes to reduce the ohmic losses and allow the cell to operate at
current densities
Developing new materials to replace older diaphragms which exhibit higher stability and are better at
facilitating ion transport
Developing high-temperature (ca 150 oC) alkaline water electrolysers to increase the electrolyte
conductivity and promote the kinetics of the electrochemical reactions at the electrodesrsquo surface
Developing new electrocatalytic materials to reduce the electrode over-potentials this present a particular
difficulty for the anode because the oxidation half-reaction is most demanding
Alkaline electrolysers (Figure 3 left) consist of two electrodes that are separated by a gas-tight diaphragm
submersed in an electrolyte solution containing a high concentration of potassium hydroxide (20-30 wt) It
should be noted that electrolytes such as sodium hydroxide and sodium chloride can also be used in some
systems and they usually operate between 40-90 oC
11 Water is reduced at the cathode to generate hydrogen
gas and hydroxide ions (OH-) which diffuse through the diaphragm to the anode where they recombine to
generate oxygen and water811
The hydrogen and oxygen produced by alkaline electrolysers have purities
gt99
In PEM electrolysers (Figure 3 right) the electrolyte is constructed from a polymeric membrane with a cross-
linked solid structure permitting a compact system with greater structural stability (able to operate at higher
temperatures and pressures)8 The electrodes used in PEM electrolysers are usually constructed from noble
metals such as platinum and iridium which limits the scope of this technology as noble metals are of limited
abundance and expensive The unit consisting of the electrodes and polymer membrane is submersed in
water Water oxidation occurs at the anode where oxygen is formed and protons are transferred through the
50
polymer membrane to the cathode where they are reduced to hydrogen PEM electrolysers are able to
produce hydrogen and oxygen of even higher purity than alkaline electrolysers at ca 9999
It should be noted that the materials needed for the electrolyte and electrodes have to be cheap and easy to
manufacture on a large scale5 Water in the gas phase diffuses into the porous cathode where it dissociates
into hydrogen and oxygen at reaction sites81
At this point the hydrogen diffuses out of the cathode and is
collected The oxygen ions are transported through the electrolyte solution to the porous anode where they
are oxidised to oxygen and collected this process is demonstrated in Figure 35 The material chosen for the
cathode has to be able to support the diffusion of steam the reduction of steam and the diffusion of hydrogen
These requirements limit the number of suitable materials that can be used to noble metals such as platinum
and gold and non-precious metals such as copper and nickel However like the artificial photosynthetic
systems previously discussed the use of noble metals is unfavourable due to their rarity and high costs The
anode has to be chemically stable under similar conditions to the cathode which means that noble metals are
again candidate materials along with electronically-conducting mixed oxides5
Electrolyte This must be a chemically stable dense gas-tight material with good ionic conductivity and
low electronic conduction The electrolyte has to be stable enough to withstand the high temperatures
associated with the chemical reactions taking place It has to be gas-tight to limit the recombination of
protons and O- to hydrogen and oxygen respectively The electrolyte should also be as thin as possible so
as to minimise the ohmic overpotential5
Electrodes It should be noted that the following properties are the same for both the anode and cathode
The electrodes have to be porous enough to allow the transportation of hydrogen and oxygen and need to
have a similar thermal expansion coefficient to the electrolyte so as to limit the amount of mechanical
stress the components exert on each other They must also be chemically stable in highly
oxidisingreducing environments and high temperatures5
To ensure that the SOEC is operating at its maximum efficiency a number of parameters need to be
quantified this is often done through modelling the system Some of the parameters measured include the
composition of the cathode inlet gas cathode flow rate and cell temperature39
When generating syngas in a
SOEC the carbon dioxide is fed into the cathode side of the device where the hydrogen is generated
51
Table 32 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the performance data for each device This table was originally constructed by Ursua et al 201211
Manufacturer
Technology
(configuration)
Production
(Nm3h)
Rated Power
(kW)b
Energy
Consumption
(kWhNm3)c
Efficiency
()d
Maximum
Pressure
H2 purity
(vol)
Location
AccaGen Alkaline (monopolar) 1-100 67-487 6-487 528-727 10 999 Switzerland
Avalance Alkaline (bipolar) 04-36 2-25 543-5 652-708 448 na USA
Claind Alkaline (bipolar) 05-30 na na na 15 997 Italy
ELT Alkaline (bipolar) 3-330 138-1518 46-43 769-823 1 998-999 Germany
ELT Alkaline (bipolar) 100-760 465-3534 465-43 761-823 30 993-998 Germany
Erredue PEM (bipolar) 06-213 36-108 6-51 59-698 25-4 993-998 Italy
Giner Alkaline (bipolar) 37 20 54 655 85 na USA
Hydrogen Technologies Alkaline (bipolar) 10-500 43-2150 43 823 1 999 Norway
Hydrogenics PEM (bipolar) 10-60 54-312 54-52 655-681 10 999 Canada
Hydrogenics Alkaline (bipolar) 1 72 72 492 79 9999 Canada
H2 Logic Alkaline (bipolar) 066-4262 36-213 545-5 649-708 4 993-998 Denmark
Idroenergy Alkaline (bipolar) 04-80 3-377 75-471 472-752 18-8 995 Italy
Industrie Haute Technology Alkaline (bipolar) 110-760 5115-3534 465-43 761-823 32 998-999 Switzerland
Linde Alkaline (bipolar) 5-250 na na na 25 999 Germany
PIEL division of ILT Technology Alkaline (bipolar) 04-16 28-80 7-5 506-708 18-8 995 Italy
Proton OnSite PEM (bipolar) 0265-30 18-174 73-58 485-61 138-15 99999 USA
Sagim Alkaline (bipolar) 1-5 5-25 5 708 10 999 France
Teledyne Energy Systems Alkaline (bipolar) 28-56 na na na 10 99999 USA
Tredwell Corporation PEM (bipolar) 12-102 na na na 75 na USA
52
332 Current status review of the state of the art
This section will focus on the advancements that have recently been made in regards to SOECs Much of the
research being conducted on SOECs is focused on increasing the efficiency and stability of the electrolyte and
electrodes by changing the temperature the SOECs operate at gas mixtures and the materials the cells are
constructed from
The most common electrolyte material used in SOECs yttria-stabilised zircona (YSZ) due to it having a high
thermal stability high oxygen ion conductivity and low cost To generate YSZ zirconia (ZrO2) can be doped
with compounds such as Y2O3 and Yb2O3 to improve the stability and conductivity Sc2O3 can also be used to
generate scandia-stabilised zirconia (ScSZ) Other co-dopants such as TiO2 and Al2O3 can be added to
further enhance the stability587
Scandium stabilised zirconia (ScSZ) has a higher conductivity than YSZ but
is not as widely used due to the high costs associated with it It should also be noted that the dopant
concentration has to be of a specific amount in order to ensure the conductivity is at its maximum It has been
shown that different dopant concentrations change the lattice structure of the ZrO2 over time which leads to
the decrease in conductivity5 The dopant chosen for the SOEC is also dependent on the temperature the cell
will have to operate at as the dopant will change the conductivity of the electrolyte at different temperatures
Researchers recently investigated the effect temperature (550 oC ndash 750
oC) had on the performance of SOEC
cells with the following layout a Ni-YSZ support layer (680 microm) a Ni-ScSZ cathode-active layer (15 microm) a
ScSZ electrolyte layer (20 microm) and a LSM-ScSZ anode layer (15 microm) The performance of the cell was
observed to decrease with decreasing temperature when the same gas composition was used (143 CO
286 H2O and 571 Argon) As the temperature decreased the ionic conductivity of the electrolyte layer
decreased The mass transfer was the rate-determining step for the electrodes at temperatures lt750 oC
Methane was only detected in the gas products when the input gas composition was the same as above the
cell temperature was lt700 oC and the operating voltage was gt 2 V
81 (TRL 3)
Electrolyte materials such as ceria- and LaGaO3-based electrolytes are showing promise at intermediate
temperatures when they are doped with other compounds that increase their ionic conductivity79
Recently
researchers developed SOEC capable of steam and carbon dioxide co-electrolysis The cell was constructed
from Ni-YSZ (nickel-yttria-stabilized zirconia) solid oxide cell with a bi-layered ScSZGDC electrolyte structure
and a LSCF (lanthanum strontium cobalt ferrite) oxygen electrode When the device was operated at 800 oC
the cell exhibited a high electrolysis current density of about 22 A cm2 and 19 Acm
2 in steam and carbon
dioxide electrolysis respectively The structural integrity of the cell was checked after the experiment and no
cracking or delamination of the electrolyte or the electrolyteelectrode was observed88
(TRL 4)
Researchers were recently able to directly synthesise methane by co-electrolysing carbon dioxide and water
to form carbon monoxide and hydrogen then conducting Fischer-Tropsch synthesis in tubular solid oxide
electrolysis cells7 As previously discussed the reduction of water in SOECs requires very high temperatures
(ca 800 oC) however with the Fischer-Tropsch process lower temperatures (ca 250
oC) are required Using
the experimental setup shown in Figure 3 researchers were able to achieve a methane yield of 1184
which means that 41 of carbon dioxide is converted to methane over the course of the 24-hour test7 The
equipment consists of a SOEC tube with a hole running through its length while the wall of the tube consists
of three layers that are structured in a similar fashion to that shown in Figure 3 it consists of an anode an
electrolyte and a cathode The first section of the SOEC tube is heated to 800 oC to allow syngas to be
generated after which the tube cools over a gradient to 250 oC to allow methane production to take place
(TRL 4)
53
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis cell electrolysers This table
was originally constructed by Carmo et al 20138
Alkaline Electrolysis PEM Electrolysis SOEC Electrolysis
Advantages
Well-established technology High current densities Efficiency up to 100
Non-noble metal catalysts High voltage efficiency Efficiency gt 100
Long-term stability Good partial load range Non-noble metal catalysts
Relative low cost Rapid response system High pressure operation
Stacks in the megawatt range Compact system design
Cost effective High gas purity
Dynamic operation
Disadvantages
Low current densities High cost of components Laboratory stage
Crossover of gases Corrosive environment Bulky system design
Low partial load range Low durability Low durability
Low dynamics Stacks below megawatt range Little costing information
Corrosive electrolyte
Figure 39 A schematic diagram of co-electrolysis and the Fischer-Tropsch process being conducted in a tubular solid oxide
electrolyser that is able to produce CH4 This figure was originally generated by Chen et al 20147
333 Patents
The cell was composed of separate anode and cathode chambers separated by a membrane that allows the
transport of sodium ions (Na+) the anode and cathode chambers are in contact with water Oxygen is
collected in the anode chamber and hydrogen is collected in the cathode chamber following which hydrogen
and carbon dioxide are reacted together to generate syngas and oxygen as by-products that need to be
separated The electrode materials were described as being ceramic that could be doped with a catalyst
material such as cobalt cerium europium or cadmium combinations of these elements were also permitted89
(TRL 3)
A patent was filed in 2011 detailing a design for SOEC that could co-electrolyse steam and carbon dioxide to
produce syngas The cell consisted of a cathode composed of nickel-zirconia an anode consisting of
strontium doped lanthanum manganite and the electrolyte between the two electrodes was composed of
yttria-stabilised zirconia the whole cell was designed to operate between 800-1000 oC The authors stated
that the electrical power to run the device would be sourced from nuclear power however it should also be
possible to run this device off solar energy This device operated with the carbon dioxide being fed into the
cathode section where the hydrogen is generated90
(TRL 4)
54
A patent was filed in 2013 detailing a modified anodeelectrolyte structure for a solid oxide electrochemical
cell where the role of the anode is to react with fuel (steamhydrocarbons) The cathode (when in SOEC
mode) consisted of a backbone of electronically conductive perovskite oxides selected from the group
consisting of niobium-doped strontium titanate vanadium-doped strontium titanate and tantalum-doped
strontium titanate mixtures were also permitted The electrolyte material consisted of a scandia and yttria-
stabilised zirconium oxide91
(TRL 2-3)
334 Future development main challenges
Technologies that are capable of electrolysing water cover a variety of TRLs wherein alkaline and PEM
electrolysers used to generate hydrogen by the water-splitting reaction have TRLs 7-8 as they have been
commercialised can be purchased and can produce power at the low megawatt scale However they are
currently not a viable option to generate power at the megawatt scale Newer SOEC technologies currently
being developed have lower TRLs (3-5) but are showing great promise in that their efficiencies are high and
they are cheap to produce
Technologies capable of co-electrolysing water and carbon dioxide to syngas are at an early stage of
development - TRLs 2-4 Research is still focused on studying how cell conditions can be manipulated to
optimise the production of syngas and hydrocarbons Research is also focused on improving the long-term
stability of the electrolytes and electrodes used in SOECs by investigating new materials and cell designs that
are cheap and easy to construct It will also be necessary to conduct duration experiments In terms of their
commercial viability they are far behind PVs at roughly the same stage as PEC technologies and ahead of
synthetic biology systems
SOECs could prove to be an efficient method by which electrical energy generated from renewable sources
(wind and solar) could be stored in the form of chemical bonds To date it has been proven that syngas can
be generated from SOECs and that methane can also be generated within the same system through a
Fischer-Tropsch process More research is needed that aims to improve the efficiency by which methanol can
be generated and to determine whether more complex hydrocarbons can be synthesised
The success of this technology is likely to be dependent on how well systems that generate electricity from
renewable sources can be integrated within it It has been suggested that nuclear wind and solar power
stations could be used to provide the electrical power required This would help to lower the cost of this
technology as sourcing the electricity needed is one of the major costs It should be noted that one of the
most commonly cited advantages of this technique over solar and wind power is that it is not site-specific
However if solar and wind power were to be used to generate the electricity needed for this technology then
it becomes a site-specific technology again This is also a problem for PEC-cell-based technologies
34 Summary
The aim of this brief literature review was to highlight the advancements that have been made across the main
technologies within artificial photosynthesis discuss some of the most recent technological solutions that have
been developed in these areas and identify the main challenges that need to be addressed for each
technology before they can be commercialised
Synthetic biology amp hybrid systems
Synthetic biology amp hybrid artificial photosynthetic systems are currently capable of producing small amounts
of fuel molecules such as hydrogen and simple hydrocarbons The majority of the technologies in this
category are at the research and development stage (TRL 1-4) To date there are no large scale plans to
produce solar fuels at a commercial level using this technology It should be noted that synthetic biology amp
hybrid systems are currently used to produce fine chemicals at the commercial level but these are not needed
55
in the large quantities in which solar fuels are required It is currently too early to comment on the long-term
commercial viability of this technological pathway however the research in this area is progressing quickly
and as our fundamental understanding of biological systems increases progression is promising It should be
noted that these systems are becoming efficient enough to produce hydrogen at a rate that is comparable to
that which occurs in natural photosynthesis on a small laboratory scale
Photoelectrocatalysis of water (water splitting)
PVssemiconductors are the most advanced technology discussed in this report as they have been
commercialised and are able to generate electricity on a MW scale at facilities such as the Solar Star Power
Station and the Topaz Solar Farm31
PVssemiconductors are used in PEC technologies where they are
incorporated into the cell design and act as light absorbers Instead of the energy gained from light absorption
being used to generate electricity directly it is used to generate fuel molecules such as hydrogen from the
water-splitting reaction The hydrogen generated from this process can then be stored and used at a later time
to provide energy This is useful because PVs are only able to generate power intermittently during daylight
hours There are many examples of photoelectrocatalysis being carried out by PECs as well as suspensions
of photoactive nanoparticles and the majority of the technologies have a TRL 2-4 However it should be noted
that PVsemiconductor technologies that generate electrical power have TRL 8-9 The main challenges facing
this technology involve developing materials that have high STH efficiencies are cheap to manufacture and
are stable for long periods of time Calculations have been performed to determine the efficiencies associated
with multiple reactor plant designs These have shown that it is theoretically possible to generate large
quantities of hydrogen however that it could cost trillions to generate a significant amount of hydrogen with
current technology
Co-electrolysis
Water electrolysers such as alkaline and PEM electrolysers are considered mature technologies that have
been commercialised and have TRLs 7-8 They can be purchased and can produce power at the low
megawatt scale However they are currently not a viable option to generate power at the megawatt scale
Newer SOEC technologies that are currently being developed have lower TRLs 3-5 but are showing great
promise in that their efficiencies are high and they are cheap to produce Technologies that are capable of
generating syngas and some organic products by a Fischer-Tropsch process are in the research and
development stage (TRL 3-4) Research is currently focused on determining how SOEC conditions can be
manipulated to increase efficiency as well as identifying more stable durable and efficient compounds to
incorporate into the cell design The incorporation of SOECs into large scale solar and wind farms could prove
to be an efficient method by which electrical energy can be stored as chemical energy
The technologies discussed above show great potential in being able to convert solar energy into solar fuels
They are still in the early research phase but all technologies made significant improvements in efficiencies
lifetimes and the number of products they can produce other than hydrogen It is likely that PVs will be used to
absorb solar energy to generate electricity for SOECs or forms part of a PEC cell that generates fuel
molecules It should be noted that wind power could be used to provide the electricity needed for SOECs to
operate which would allow these systems to be used outside of desert regions Biological systems currently
look to be less suitable for producing large quantities of fuel molecules partly due to their early research stage
but may prove to be useful in generating highly complicated molecules once the understanding of protein
engineering has increased
All of these technologies seek to improve device lifetimes increase efficiency lower manufacturing costs and
increase the scope of synthetic fuels that can be produced Switching to a hydrogen economy will require
large and expensive infrastructure changes Using hydrogen to generate more complex fuel molecules will
require more research however ultimately fewer infrastructure changes
57
4 Mapping research actors
41 Main academic actors in Europe
In Europe research on AP is conducted by individual research groups or in research networks or consortia
Most of the research groups are located in Germany the Netherlands and Sweden The largest country-based
networks are also in Sweden and in the UK Most of Germanyrsquos research groups are part of the pan-European
AP network AMPEA The number of research groups has increased substantially since the 1990s when the
field became more prominent coupling with the (exponential) rise of publications in AP3
411 Main research networkscommunities
In this section we describe the main research networkscommunities on artificial photosynthesis in Europe
Under networks we indicate co-operations with multiple universities research organisations and companies
Instead of focusing strictly on major integrated research on specific AP topics the networks mostly have a
broad research and collaboration focus Larger joint programmes exist but are more focused on various key
priorities in Europe for different research areas such as AMPEA (Advanced Materials and Processes for
Energy Application) which is one of the joint programmes of EERA (European Energy Research Alliance) of
which artificial photosynthesis is one of the three identified applications The first national research network
dedicated to artificial photosynthesis was the Swedish Consortium for Artificial Photosynthesis (CAP)
following which a number of other national and pan-European networks emerged in the past few years
Research networks and communities play an important role in facilitating collaboration across borders and
among different research groups The development of AP processes needs expertise from molecular biology
biophysics and biochemistry to organometallic and physical chemistry Research networks provide the
platform for researchers and research teams from those diverse disciplines to conduct research together to
create synergistic interactions between biologists biochemists biophysicists and physical chemists all
focusing on questions relevant for AP and solar fuels This need for research coordination is reflected by the
fact that the Swedish Consortium for AP was a bottom-up initiative by university-based scientists4
Furthermore networks are effective for promoting AP research and raising public awareness and knowledge
about AP5
Networks and consortia with industrial members also play an important role with respect to the goal of turning
successfully developed AP processes into a commercially viable product Research and innovation in
materials and processes of AP can be backed up by private innovation and investments Feedback on the
applicability of research outputs can be incorporated and shape further research efforts and application
possibilities in the business sector can be discovered
The advantages and synergy effects of network membership for research groups are reflected in the fact that
more than 50 of European research groups are part of a research network in Europe The consortia vary in
their membership and their funding sizes whereas about 400 researchers are affiliated with the pan-European
consortium AMPEA the Swedish CAP unites about 80 scientists Furthermore it is apparent that only AMPEA
is a truly pan-European consortium member research groups come from various European countries such as
Austria France Czech Republic Germany Italy the Netherlands Norway Spain Sweden Switzerland and
3 V Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in
ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press) conducted a bibliometric analysis using key words related to the field of artificial photosynthesis showing that only a few papers were published before the 1990s reaching more than 900 publications in 2014
4 httpwwwsolarfuelse
5 httpsolarfuelsnetworkcomoutreach
58
the UK Most of the other consortia discussed below are based in a specific country which is reflected in their
affiliations among research groups
EU - AMPEA
The European Energy Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials
amp Processes for Energy Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging
Technologies and artificial photosynthesis became the first energy research subfield to be organised within
AMPEA The goal of this joint programme which was launched at the end of 2011 is to set up a thorough and
systematic programme of directed research which by 2020 will have advanced to a point where commercially
viable artificial photosynthetic devices will be under development in partnership with the industry Its goal to
boost research on a pan-European basis is reflected in the fact that to date more than 40 European scientific
institutions participate Many institutes in different Member States are associated with AMPEA (31 full
members for example CEA DIFFER TU Delft JKU Max Planck Institute)6 The research efforts of the
AMPEA participants aim at advancing all of the three identified pathways of artificial photosynthesis Due to
the low availability of efficient molecular catalysts based on earth-abundant elements the search for those
elements and the development of such catalysts constitute the early research focus
Italy ndash SOLAR-CHEM
In 2009 the universities of Bologna Ferrara and Messina founded SOLAR-CHEM the Italian inter-university
centre for the chemical conversion of solar energy7 Later on other universities in Italy also joined SOLAR-
CHEM The research efforts of the centre aim to foster research in solar fuels through a multidisciplinary
approach and coordination activities eg through the organisation of dedicated events and through short-term
exchanges of staff in the network
Netherlands ndash BioSolar Cells
The Dutch BioSolar Cells public-private partnership was established in 2010 BioSolar Cells is a cooperation
of 10 knowledge institutions such as Leiden University Delft University of Technology and the University
of Twente8 as well as 45 private industries
9 The programme is funded by FOMALWNWO the Dutch
ministry of Economic Affairs Agriculture and Innovation many companies and a number of Dutch universities
and research organisations The BioSolar Cells programme has three themes artificial photosynthesis
photosynthesis in cellular systems and photosynthesis in plants These three research themes are
underpinned by a fourth theme education and societal debate where educational modules are developed to
equip and inspire future researchers policy makers and industrialists and where the societal consequences
of new solar-to-fuel conversion technologies are debated10
Sweden - CAP
Founded in 1994 the Swedish Consortium for Artificial Photosynthesis carries out integrated basic
research with the goal to produce applicable outcomes such as fuel from solar energy and water Their
projects integrate two topics artificial photosynthesis in man-made systems to make hydrogen from sun and
water and photo-biological fuel production in living organisms They focus on photoelectrocatalysis as the
technology pathway yet are also building on their research on the principles of natural photosynthesis for
energy production A unique component in the consortium is hence the synergistic interactions between
biologists biochemists biophysicists and physical chemists all focusing on questions relevant for solar
fuels11
The academic partners come from Uppsala University Lund University and the KTH Royal
Institute of Technology in Stockholm
6 httpwwweera-seteueera-joint-programmes-jpsadvanced-materials-and-processes-for-energy-application-ampea
7 httpswwwsocchimitsitesdefaultfileschimindpdf2012_6_88_capdf
8 httpwwwbiosolarcellsnlover-biosolar-cellsnew_page_1html
9 httpwwwbiosolarcellsnlover-biosolar-cellsbedrijvenhtml
10 httpwwwbiosolarcellsnlonderzoek
11 httpwwwsolarfuelsesolar-fuels
59
UK ndash SolarCAP
The SolarCAP Consortium for Artificial Photosynthesis is a consortium of four UK academic research groups
funded by the Engineering and Physical Sciences Research Council The groups based in the Universities
of East Anglia Manchester Nottingham and York12
are specifically exploring the solar conversion of
carbon dioxide to carbon monoxide in tandem with the conversion of methane or alkanes to useful oxygen-
containing products such as alcohols They are exploring the second technological pathway of
photoelectrocatalysis
UK ndash Solar Fuels Network
Solar Fuels Network brings together academic and industrial researchers in solar fuels and artificial
photosynthesis It aims to develop an effective community of solar fuels researchers from both academia and
industry to raise the profile of the UK solar fuels research community nationally and internationally Through
this it aims to promote collaboration and co-operation with other research disciplines industry and
international solar fuels programmes and to contribute towards the development of a UK solar fuels
technology and policy roadmap The networkrsquos management team is based at Imperial College London and
is led by Prof James Durrant Partner organisations encompass the Royal Society of Chemistry the Energy
community of the Knowledge Transfer Network (KTN) the Solar Fuels Institute (SOFI) and the Foreign and
Commonwealth Officersquos Science and Innovation Network13
In other countries across Europe national initiatives have emerged in the last few years and more are
expected to in the future For example the Photoelectrochemistry Competence Center (PECHouse and
PECHouse2)14
under coordination of the Ecole Polytechnique Federale de Lausanne (prof Michael Graumltzel)
has been created in Switzerland while in France artificial photosynthesis is being researched by laboratories
of excellence (LabEx Arcane15
and LabEx Charmatt16
)
412 Main research groups (with link to network if any)
A list of the main research groups in Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire Artificial
Photosynthesis community Taking that into account the numbers presented below may provide an indication
of the AP research sector as a whole
Table 41 Number of research groups and research institutions in European countries
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Austria 1 1 15
Belgium 1 1 -
Czech Republic 1 1 -
Denmark 3 2 -
Finland 1 1 6
France 5 3 14
Germany 31 17 16
Ireland 1 1 7
Italy 5 5 29
Netherlands 28 9 18
Norway 1 1 -
12
httpwwwsolarcaporgukresearchgroupsasp 13
httpsolarfuelsnetworkcommembership 14
httppechouseepflchpage-32075html 15
httpswwwlabex-arcanefrencontentlaboratoires-excellence-arcane 16
httpwwwcharmmmatfrindexphp
60
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Spain 4 4 11
Sweden 13 5 17
Switzerland 5 5 10
UK 13 9 10
Total 113 65 15
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 66 main research institutions and universities working on artificial photosynthesis in Europe
Those research institutions contain 113 individual research groups with an average size of about 15
people17
The sizes of research groups can vary widely from for example 80 members of a research group at
Imperial College London to only two persons in the research group of Klaus-Dieter Weltmann at the Leibniz
Institute for Plasma Science and Technology The country with both the highest number of involved institutions
and research groups is Germany where 32 individual research groups in 17 research institutions are active
Germany is followed by the Netherlands with nine institutions and 28 research groups and by Sweden with
five institutions and 13 research groups Almost half (47) of the research groups focus on the second
pathway ie photoelectrocatalysis whereas 36 research the first pathway ie the usage of synthetic
biology and hybrid systems to produce fuel molecules and about 17 follow the third pathway in their
research which is co-electrolysis A bulk of the research in most countries is done on the second pathway
except for in Sweden and Finland which seem to specialize in exploring the first pathway Table 42 provides
an overview of some of the key statistics the number of research groups and research institutions in AP per
country and the number of research groups focusing on each of the three technological pathways
respectively
Table 42 Number of research groups per research area (technology pathway)
Country Total Synthetic biology
amp hybrid systems
Photoelectrocatalysis Co-electrolysis
Austria 1 1 1 0
Belgium 1 1 1 0
Czech Republic 1 0 1 0
Denmark 3 0 2 2
Finland 1 1 0 0
France 5 2 5 0
Germany 31 14 15 9
Ireland 1 1 1 0
Italy 5 0 5 0
Netherlands 28 12 17 9
Norway 1 0 1 0
Spain 4 2 3 1
Sweden 13 10 7 0
Switzerland 5 1 5 3
UK 13 8 5 1
Total 113 53 69 25
Source Ecorys
17
The average group size is derived from survey responses and available information on the websites of the groups
61
In the following section our findings have been illustrated by presenting some of the main research institutions
and their research groups
Germany - Helmholz Zentrum Berlin
The Institute for Solar Fuels of the HZB is led by Prof Roel van de Krol The institute pursues a strategy to generate
hydrogen via the second technology pathway they combine the energy conversion of light into electrical energy via
photonic stimulation of the semiconductor directly with the catalytic procedures on the electrolyte-electrode-interface for
the conversion into storable chemical energy (hydrogen) The generated hydrogen can then be stored by means of
already known methods (compressed gas liquid-H2 metal hydride conversion to methanol) Their approach combines
research and insights from photo-physics surface- and material chemistry photoelectrochemistry interface- and
surface sciences as well as system alignment18
Therefore they collaborate closely with the University of Messina in
Italy and the Leiden University in the Netherlands Moreover the HZB is also part of the European research network
AMPEA
Germany ndash Max Planck Institute for Chemical Energy
The Department of Biophysical Chemistry at the Max Planck Institute for Chemical Energy focus on the water-oxidizing
enzyme of oxygenic photosynthesis and hydrogenases Their research uses a variety of different physical techniques
to gain insight into enzymatic processes such as into photosynthetic water splitting and (bio)hydrogen production
which can be used for biomimetic chemistry ie to develop catalytic systems in energy research19
They hence focus
on the first and second technology pathways The Max Planck Institute for Chemical Energy also contributes to the
European research network AMPEA
The Netherlands - The Dutch Institute for Fundamental Energy Research
Part of the Netherlands Organisation for Scientific Research (NWO) the DIFFER institute has since its initiation in 2012
grown to an activity of about 65 Meuroyear (about 75 fte) all directed at the production of chemicalsfuels from electrons
and photons In particular as part of its solar fuels research DIFFER investigates the splitting of water into hydrogen
and oxygen using electricity and the reduction of carbon dioxide to carbon monoxide As they are located at TUe
campus in Eindhoven they can easily collaborate and share knowledge with universities universities of applied
sciences and industry The DIFFER institute also contributes to AMPEA
Sweden ndash Uppsala University
Various research teams at Uppsala University cover all three relevant technology pathways for artificial
photosynthesis20
Moreover in 2006 the Swedish Consortium for Artificial Photosynthesis (CAP) founded in 1994 by
three researchers from Uppsala University and one researcher from the University of Stockholm created a new
scientific environment at the Aringngstroumlm laboratory at Uppsala University becoming the base for this consortium
Switzerland ndash ETH Zurich
The Professorship of Renewable Energy Carriers21
performs RampD projects in emerging fields of renewable energy
engineering operates state-of-the-art experimental laboratories offers advanced courses in fundamentalapplied
thermal sciences and produces qualified scientists and engineers with expertise in renewable energy technologies
Regarding solar fuels they focus on solar splitting of H2O and CO2 via thermochemical Redox cycles which
corresponds to the third technology pathway of artificial photosynthesis They are partners in several EU projects
concerning solar-driven hydrogen production such as SOLARJET ndash Solar Production of Jet Fuel from H2O and CO2
and HYCYCLES ndash Solar Water-Splitting Thermochemical Cycle22
18
httpswwwhelmholtz-berlindeforschungoeeesolare-brennstoffeindex_enhtml 19
httpwwwcecmpgderesearchbiophysical-chemistryoverviewhtmlL=1 20
httpwwwkemiuuseresearchmolecular-biomimeticphotosynthesis 21
httpwwwprecethzch 22
httpwwwprecethzchresearchsolar-fuelshtml
62
UK ndash Imperial College London
The research of various research teams of the Imperial College London encompasses the first and second technology
pathways It ranges from research on the oxidising enzyme Photosystem II which has become the focus of attention
because cheap water-splitting catalysts are urgently needed in the energy sector to the development of
photoelectrodes and nanoparticles for solar-driven fuel synthesis based on water splitting of water into hydrogen and
oxygen Collaborations across the Imperial College London are complemented with co-operations across the UK as
part of the UK Solar Fuels Network with the Swiss Federal Institute of Technology in Lausanne (EPFL) UCL and
Cambridge University
The density of research group per country in Europe is presented schematically in Figure 41
Figure 41 Research groups in Artificial Photosynthesis in Europe
Source Ecorys
42 Main academic actors outside Europe
Also outside of Europe research on AP is conducted by individual research groups or in research networks or
consortia Most of the research groups and networks are located in the US and in Japan Whereas US-based
networks sporadically have ties to European research groups the Japanese consortia have exclusively
Japanese members both academic and industrial
421 Main research networkscommunities
Outside of Europe the main networks can be found in the US and in Japan The biggest network is the US
network JCAP (Joint Center for Artificial Photosynthesis) with more than 190 persons linked to the
programme and a budget of $122 million for five years Next in line is the Japanese ARPChem which has
roughly the same budget available for a time span of 10 years
63
Japan ndash ARPChem
The Japanese Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology jointly launched the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem) in November 2012 The aim is to bundle efforts for the next
decade to develop innovative catalysts and other materials that could be used for manufacturing fundamental
chemical substances from water and carbon dioxide by making use of solar power Such substances can be
used as raw materials of plastics synthetic fibres synthetic rubber solvents and other products and are
applicable in all areas of peoples everyday lives The expected budget for the coming decade between 2012
and 2021 amounts to 15 billion yen (euro 122 million)23
The utilisation of catalyst technology requires long-term
involvement and entails high risks in development but is expected to have a huge impact on Japans
economy and society The aim is to achieve independence from fossil resources used as raw materials for
chemical substances while overcoming resource and environmental challenges The consortium consists of
partners from academia industry and the government seven universities amongst them the University of
Tokyo the Tokyo University of Science and the Kyoto University companies such as Mitsubishi
Chemicals Mitsui Chemicals Fuji Films and TOTO and governmental research organizations such as the
National Institute of Advanced Industrial Science and Technology (AIST)
Japan ndash All Nippon Artificial Photosynthesis Project for Living Earth (AnApple)
The All Nippon Artificial Photosynthesis Project for Living Earth (AnApple) is one of the Scientific
Researches on Innovative Areas receiving strong financial support from the Ministry of Education Culture
Sports Science and Technology It was set up in 2012 as a five-year national project Although it is not a
consortium in a narrow sense its scope and research impact are substantial as more than 40 Japanese
leading scientific groups are part of this project It is led by Prof Haruo Inoue from the Tokyo Metropolitan
University further academic partners are amongst others the Tokyo University of Science the Tokyo
Institute of Technology Ibaraki University Ritsumeikan University and Hokkaido University
South Korea ndash KCAP
The Korean Centre for Artificial Photosynthesis (KCAP) was launched at Sogang University in 200924
set up
as a ten-year programme with 50 billion won (about euro40 million)25
It aims to secure a wide range of
fundamental knowledge necessary materials and device fabrication for the implementation of artificial
photosynthesis ie generating liquid fuel and oxygen from water and carbon dioxide using solar energy
through collaborative research with a number of research organisations and companies The Korean partners
comprise 14 professors from 8 universities including Sogang University Yonsei University and the Ulsan
National Institute of Science and Technology and one industry partner Pohang Steel Company26
Foreign academic partners are the Lawrence Berkeley National Laboratory California Institute of
Technology and University of California Berkeley The Centre has ties to other AP networks such as SOFI
and JCAP
US ndash JCAP
In 2010 the Department of Energy created the Energy Innovation Hubs and among them a Joint Centre for
Artificial Photosynthesis (JCAP) was established between the California Institute of Technology and the
Lawrence Berkeley National Laboratory in California27
JCAP draws on the expertise and capabilities of key
collaborators from the University of California (UCI and UCSD) and the SLAC National Accelerator Laboratory
operated by Stanford University The initial funds in 2010 amounted to $122 million JCAP is the largest
artificial photosynthesis network in the US with more than 190 persons linked to the programme The research
foci encompass electro-catalysis photo-catalysis and light capture materials integration and numerical
23
httpwwwmetigojpenglishpress20121128_02html 24
httpwwwk-caporkrenginfoindexhtmlsidx=1 25
httpwwwsogangackrnewsletternews2011_eng_1news12html 26
httpswwwicef-forumorgannual_2015speakersoctober8cs2appdfcs-2_20058_kyung_byung_yoonpdf 27
httpsolarfuelshuborgwho-we-areoverview
64
modelling test-bed prototyping and benchmarking The funds for the next five-year period (2016-2020)
amount to $75 million and are subject to congressional appropriation
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years Core members include the Northwestern University and
Uppsala University A process of exchanges is instituted which encompasses six different universities in four
countries Industry partners are ILampFS (India) Total (France) and Shell28
This list is not exhaustive and increasing interest in the field of artificial photosynthesis would certainly lead to
the launch of new national and international programmes
422 Main research groups (with link to network if any)
A list of the main research groups outside Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire AP
community outside of Europe We are confident however that it provides an accurate indication about the AP
sector outside of Europe
Table 43 Number of research groups and research institutions in non-European countries
Country Number of research groups Number of research institutions Average size of a
research group
Australia 1 1 18
Brazil 1 1 5
Canada 1 1 -
China 12 5 13
Israel 1 1 6
Japan 16 15 15
Korea 4 4 16
Singapore 1 1 14
US 40 32 18
Total 77 61 5
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 61 main research institutions or universities working on artificial photosynthesis outside of
Europe most of which are based in the US and in Japan Those research institutions contain 77 individual
research groups with an average group size of 8 people29
Yet the sizes of research groups can vary widely
from 26 members at the University of Tokyo to only two persons at Kobe University The country with both the
highest number of involved institutions and research groups is the US where 40 individual research groups in
32 research institutions are active Hence the US is a world leader in terms of research groups working on
AP Japan follows with 16 institutions and 15 research groups which lies below the numbers for Germany
and the Netherlands Almost 80 of the research groups (77) focus on the second pathway
(photoelectrocatalysis) whereas about 39 research the first pathway (synthetic biology amp hybrid
systems) The remaining 18 focus their activities on the third pathway (co-electrolysis) Table 44
28
httpwwwsolar-fuelsorgabout-sofi 29
The average group size is derived from survey responses For more information please refer to Annex I
65
provides an overview of some of the key statistics such as the number of AP research groups and institutions
per country and their respective focus on one of the three technology pathways
Table 44 Number of research groups per research area (technology pathway)
Country Technology
pathway
Total Synthetic biology
and hybrid systems
Photoelectrocatalysis Co-electrolysis
Australia 1 1 1 0
Brazil 1 0 1 0
Canada 1 0 1 1
China 12 4 6 2
Israel 1 1 0 1
Japan 16 7 15 1
Korea 4 0 4 0
Singapore 1 0 1 0
US 40 17 30 9
Total 77 30 59 14
Note a research group might focus on multiple technology pathways
Source Ecorys
In the following section our findings are illustrated by presenting some of the main research institutions and
their research groups
China ndash Dalian University of Technology
In 2011 the Dalian National Laboratory for Clean Energy (DNL) based at the Dalian Institute of Chemical Physics
(DICP) of the Chinese Academy of Sciences (CAS) was established It integrates research into clean energy and the
efficient use of fossil fuels to meet Chinas sustainable energy development strategy It is led by Li Can
Israel - Weizmann Institute of Science
To meet the challenge of providing clean sustainable energy the Weizmann Institute has established the Alternative
Sustainable Energy Initiative (AERI) The goal of this initiative is to create the conditions conducive to alternative
energy research and to identify promising avenues of research With the help of AERI the Weizmann institute hopes to
encourage its scientists to conduct basic research relevant to the future development of alternative sustainable energy
and to nourish the next generation of scientists in this field around the world in Israel and at the Weizmann Institute
The researchers at the Weizmann Institute of Science and at AERI preliminarily focus on the third pathway
Japan ndash University of Tokyo
The Domen Laboratory at the University of Tokyo is a research group focused on the second technological pathway
Their challenge is to find out novel photocatalysts that effectively work on water splitting under visible light by studying
different new materials
US ndash Arizona State University
The multidisciplinary team of the Center for Bio-inspired Solar Fuel Production of the Arizona State University aims to
design a complete system for solar water oxidation and hydrogen production Therefore they are focusing on five
specific subtasks (i) The total system analysis of the solar water-splitting device (ii) water oxidation (iii) fuel
production (iv) the artificial reaction center-antenna which relates to light collection and (v) the development of
functional nanostructured transparent electrode materials Their focus lies hence on the first and second AP technology
pathways
The density of research groups per country in the world is presented schematically in Figure 42 Please note
that in this figure (as opposed to Figure 41) we do not count each European country individually but
aggregate the numbers for all of Europe
66
Figure 42 Research groups active in the field of AP globally
Source Ecorys
43 Level of investment
In this section the level of investment is discussed in further detail The level of research investment in the EU
is based on the total budget of the projects whenever available In addition information is given on the time
period of the research projects
Information on the investment related to or funding of artificial photosynthesis research programmes and
projects at the national level is generally difficult to find especially for academic research groups Most budget
numbers found relate to the budget of the institution andor the (research) organisation in general and are not
linked to specific artificial photosynthesis programmes in particular unless the institute or research
programme is completely focused on artificial photosynthesis
Table 45 presents an overview of the investments made by a number of organisations
Table 45 Investments in the field of artificial photosynthesis
Country Organisation Budget size Period
Research investments in Europe
EU European Commission (FP7 and previous
funding programmes) euro 30 million 2005 - 2020
France CEA euro 43 billion 2014 covers not only AP
Germany
German Aerospace Centre (DLR) and the
Helmholtz Zentrum euro 4 billion
Annual budget covers
not only AP
Germany
Max Planck Institute for Chemical Energy
Conversion euro 17 billion 2015 covers not only AP
Germany
BMBF ldquoThe Next Generation of
Biotechnological Processesrdquo euro 42 million 2010 - present
Germany Government of Bavaria euro 50 million
2012-2016 covers not
only AP
Members of AMPEA AMPEA (EERA) euro 60 million 2010 - present
Netherlands Biosolar Cells euro 42 million 2010-present
Sweden Consortium for Artificial Photosynthesis euro 118 million 2013
UK SolarCAP and other initiatives in UK euro 92 million 2008-2013
67
Country Organisation Budget size Period
UK
University of East Anglia Cambridge and
Leeds euro 1 million 2013
Research investments outside Europe
China Dalian National Laboratory for Clean Energy euro 40 million Annual budget since
2011
Israel AERI euro 13 million 2014-2017
Japan ARPChem euro 122 million 2012 - 2021
Korea KCAP euro 385 million 2009 - 2019
UK US Plug-and-play photosynthesis euro 44 million 2014 - 2017
US JCAP euro 175 million 2010 - 2020
US SOFI euro 1 billion 2012 - 2022
Source Ecorys
431 Research investments in Europe
In Europe national researchers research groups and consortia are generally funded by European funds (such
as the ERC Grant from the European Commission) national governments businesses and universities In this
section special attention is paid to the EU FP7 projects These projects are mainly funded by European
contributions Further information is provided on AMPEA BioSolar Cells CAP SolarCap and some other AP
initiatives
Investments range between euro10 million for the national consortia (UK - SolarCap and Sweden - CAP) and euro42
million for the Dutch consortium to smaller budgets for local projects The projects at the European level are
more extensive The funds for all twenty FP7 projects related to artificial photosynthesis amount to a total
value of euro30 million AMPEA consists of around 400 professionals and an investment of approximately euro60
million contributed by the participants and associates themselves
Funding of AP research programmes and research consortia
EU ndash FP6 and FP7 projects
The FP6 and FP7 projects (6th
and 7th Framework Programmes for Research and Technological
Development) were undertaken in seven years between 2002 and 2013 and had a total budget of over euro60
billion30
Within FP7 around two thirds of the overall budget was aimed for the Cooperation programme of
which energy is one of the ten key thematic areas Investment in energy research under EU FP7 has been
around euro25 billion Various projects on artificial photosynthesis solar-powered hydrogen production by means
of water splitting have been completed under the EUrsquos Seventh Framework Programme Projects include
inter alia Solhydromics Solar-H Directfuel and H20Split FP7 is the key tool to respond to Europersquos needs in
terms of jobs and competitiveness and to maintain leadership in the global knowledge economy31
The
successor programme of FP7 has a number of projects in the field of artificial photosynthesis For example
PECDEMO project32
aims to develop a hybrid photoelectrochemical-photovoltaic tandem device with a solar-
to-hydrogen efficiency of 8-10 This illustrates the trend to move from fundamental research of materials and
processes (that was the main focus in FP6 and FP7 programmes) to the development of prototypes to reach
higher TRL levels (that is the main focus in H2020 programme)
An overview of the EU FP6 and FP7 projects on AP is presented in the table below
30
httpseceuropaeuresearchfp6pdffp6-in-brief_enpdf httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 31
httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 32
httppecdemoepflchpage-113311-enhtml
68
Table 46 EU FP6 and FP7 projects on artificial photosynthesis
EU FP7 project Technology pathway Total budget EU contribution to
the total budget
Time
period
(months)
ARTIPHYCTION Photolectrocatalysis (Water Splitting ) euro 3594581 euro 2187040 36
DIRECTFUEL Synthetic Biology amp Hybrid Systems euro 4977781 euro 3729519 48
CO2PHOTORED Photolectrocatalysis (Water Splitting ) euro 176053 euro 176053 24
COFLeaf Photolectrocatalysis (Water Splitting ) euro 1497125 euro 1497125 60
EWOCS Photolectrocatalysis (Water Splitting ) euro 168896 euro 168896 24
FAST MOLECULAR
WOCS
Photolectrocatalysis (Water Splitting )
euro 100000 euro 100000 48
H2OSPLIT Photolectrocatalysis (Water Splitting ) euro 100000 euro 100000 48
HJSC Research for fundamental understanding euro 337094 euro 337094 36
NANO-PHOTO-
CHROME
Synthetic Biology amp Hybrid Systems euro 218731
euro 218731 17
HyMap Photolectrocatalysis (Water Splitting ) euro 2506738 euro 2506738 60
PCAP Photolectrocatalysis (Water Splitting ) euro 190800 euro 190800 36
PHOTOCATH2ODE Photolectrocatalysis (Water Splitting ) euro 1500000 euro 1500000 60
PHOTOCO2 Photolectrocatalysis (Water Splitting ) euro 50000 euro 50000 24
PS3 Synthetic Biology amp Hybrid Systems euro 1997944 euro 1997944 60
SOLAR-H Synthetic Biology amp Hybrid Systems euro 2316000 euro 1800000 36
SOLAR-JET Photolectrocatalysis (Water Splitting ) euro 3123950 euro 2173548 48
SOLHYDROMICS Synthetic Biology amp Hybrid Systems euro 3655828 euro 2779679 42
SUSNANO Catalysts can be either used for hybrid
systems or the water splitting category euro 100000
euro 10000 54
TRIPLESOLAR Photolectrocatalysis (Water Splitting ) euro 2493585 euro 2493585 60
light2hydrogen Photolectrocatalysis (Water Splitting ) euro 900000
Total euro 30005106 euro 24016752 821
Source FP7 Project list
In total euro30 million of which 80 were based on European contributions have been spent on 20 projects
related to artificial photosynthesis Most projects were completely funded by the European Union On average
the time period of these projects was around 43 months the shortest project lasting only 17 months and the
longest one 60 months Almost all funding related to the topics of photoelectrocatalysis (55) and synthetic
biology amp hybrid systems (44) Some additional funding was spent on research for fundamental
understanding (the HJSC project) and catalysts which are useful for either hybrid systems or water splitting
(the SUSNANO project)
Table 47 Total EU budget on artificial photosynthesis per technology pathway
Technology pathway TRL Total budget
Synthetic biology amp hybrid systems 1-2 euro 13166284
Photoelectrocatalysis (water splitting ) 1-4 euro 16401728
Catalysts that can be used for both categories above 1-4 euro 100000
Research for fundamental understanding - euro 337094
Total - euro 30005106
69
Based on the monthly funding of the FP7 projects33
it may be observed that annual investments in artificial
photosynthesis have been increasing over the years (Figure 43) There were no projects on artificial
photosynthesis in 2008 therefore no investments were made The highest investment was made in 2014 with
euro45 million spent on projects After that investments have been decreasing It is however expected that
from 2016 more projects on artificial photosynthesis will be conducted therefore investment will rise
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020
Note It is assumed that the funding of the projects is evenly distributed over months Thus annual expenditures are
calculated as a sum of the monthly expenditures Project lsquolight2hydrogenrsquo is excluded from the calculation since there is no
information available on the number of months the project is running
Source Ecorys
EU ndash AMPEA (EERA)
EERA is an alliance of leading organisations in the field of energy research comprising more than 150
participating organisations all over Europe The primary focus of EERA is to accelerate the development of
energy technologies to the point that they can be embedded in industry-driven research Activities of EERA
are based on the alignment of own resources while over time the Joint Programmes can be expanded with
additional sources including from Community programmes34
In EERA approximately 3000 FTE (equivalent
of 3000 professionals) are involved which makes for a budget of around euro450 million35
AMPEA is one of the
programmes under EERA focusing on AP in which roughly 400 professionals are involved This would then
make for an investment of approximately euro60 million for AMPEA
The Netherlands ndash BioSolar Cells
The total budget of BioSolar Cells is around euro42 million based on public and private funds The Ministry
contributed euro25 million the NWO (The Dutch organisation on Scientific Research) euro35 million and Dutch
universities and research centres around euro7 million Private organisations invested euro65 million The specific
research programme Towards Biosolar Cells in which the Delft University of Technology is involved is
being allocated a budget of euro25 million by the Dutch Ministry of Agriculture Nature and Food Quality A
benefit of funding partly by private funding is the focus on building infrastructure and retaining key
33
It is assumed that funding is spread evenly over the months that the project is being implemented This means that if a project is running 36 months with a total budget of euro1 million it is assumed that monthly investments are euro83000 (1 million 12) If a project started in May 2010 then investment over the whole year 2010 is calculated as 8euro83000 After annual investment is calculated for all projects yearly total investment is calculated as a sum across projects
34 httpssetiseceuropaeuimplementationtechnology-roadmapeuropean-energy-research-alliance-eera
35 httpwwwapreitmedia168877busuoli_eneapdf
70
researchers Public funding of artificial photosynthesis is mostly for the short term facilitating the entry of new
groups36
Swedish ndash CAP
The Swedish Consortium for Artificial Photosynthesis connecting the universities of Lund Stockholm and
Uppsala is chaired by Stenbjoumlrn Styring There are 80 persons linked to the consortium In 2013 the Swedish
Energy Agency distributed the amount of euro118 million (SEK 108 million) in total to lsquosome of Swedenrsquos best
research groupsrsquo Out of this amount euro87 million went to three research groups at Uppsala University euro37
million to research on artificial photosynthesis to generate solar fuels euro32 million for research on dye-
sensitised solar cells and euro18 million to research on thin film solar cells (TFSC) It is the largest one-time
investment in solar energy ever in Sweden37
The Swedish Consortium for Artificial Photosynthesis ndash Stenbjoumlrn Styring
The project Molecular Solar Energy Sciences is funded by the KampA Wallenberg Foundation with euro5 million The main
research activities related to artificial photosynthesis include mechanistic studies on synthetic molecular and
moleculesemiconductor systems for the light-driven reduction of protons and CO2 and oxidation of water Furthermore
research is conducted on cyanobacteria systems for photo-biological fuel generation synthetic biology molecular
biology and metabolic engineering A second project on artificial photosynthesis is funded by the Swedish Energy
Agency (euro4 million) An additional four projects are funded by Swedish and European sources with a total of euro5
million38
UK ndash SolarCAP and others
The Engineering and Physical Sciences Research Council (EPSRC) in the UK supports several AP-related
projects through the Towards a Sustainable Energy Economy programme39
The total amount of funding is
approximately euro92 million
New and Renewable Solar Routes to Hydrogen is led by Imperial College London and is targeting both
artificial and natural photosynthetic routes to solar-derived hydrogen (euro5 million)40
Artificial Photosynthesis Solar Fuels is led by the University of Glasgow (euro2 million)41
The SolarCAP consortium for Artificial Photosynthesis is a consortium of five UK academic research
groups (based at the Universities of East Anglia Manchester Nottingham and York) they are working to
develop solar nanocells for the production of carbon-based solar fuels (euro22 million)
Funding of other AP initiativesprojects
Germany ndash German Aerospace Centre (DLR) and the Helmholtz Zentrum
The Helmholtz Zentrum is Germanyrsquos largest scientific organisation with more than 38000 employees and an
annual budget of more than euro4 billion42
It consists of 18 scientific technical biological and medical research
centres The research institutes of the German Aerospace Centre (DLR) are affiliated with the Helmholtz
Zentrum One of the Institutes of DLR the Institute of Solar Research forms part of the Helmholtz Zentrum
programme for renewable energies This programme focuses on projects on cost reduction in solar thermal
power plants the thermo-chemical generation of solar fuels in the period 2015-2019 the solar tower in Juumllich
the bioliq pilot plant and the Gross Schoumlnebeck geothermal research platform43
Research institutes submit
their research projects for evaluation by an international panel in order to qualify for funding under the
Renewable Energies Programme based on the outcome the Helmholtz Zentrum makes funding
recommendations for a five-year period
36
httpbiomassmagazinecomarticles2883towards-biosolar-cells-program-receives-government-funding 37
httpwwwuuseennewsnews-documentid=2282amptyp=artikelamparea=2amplang=en 38
Information is based on the survey responds 39
httpwwwrscorgglobalassets04-campaigning-outreachrealising-potential-of-scientistsresearch-policyglobal-challengessolar-fuels-2012pdf
40 httpgowepsrcacukNGBOViewGrantaspxGrantRef=EPF00270X1
41 httpgtrrcukacukprojectsref=EPF0478511
42 httpwwwdlrdesfendesktopdefaultaspxtabid-888515347_read-37692
43 httpwwwhelmholtzdeno_cacheenresearchenergyrenewable_energies
71
Germany ndash The Max Planck Institute for Chemical Energy Conversion (MPI CEC)
The MPI CEC was founded in 2012 to focus on the issue of energy conversion Its researchers analyse the
basic processes of energy storage and conversion within three research departments which encompass 200
employees44
The MPI CEC is for the most part financed by public funds from both the German state and
regions The MPI CEC is part of the Max Planck Society for the Advancement of Science which is a formally
independent non-governmental and non-profit association of German research institutes The budget of the
entire society amounted to euro17 billion in 2015
Germany ndash Federal Ministry of Education and Research (BMBF)
In 2010 the BMBF launched the initiative ldquoThe Next Generation of Biotechnological Processesrdquo45
Part of this
initiative were deliberations directed toward simulating biological processes for material and energy
transformation A funding amounting euro42 million is available for the first 35 projects on microbial fuel cells
artificial photosynthesis and universal production46
Germany ndash SolTech (Solar Technologies Go Hybrid)
The Government of Bavaria initiated SolTech an interdisciplinary project to explore innovative concepts for
converting solar energy into electricity and non-fossil fuels The project brings together research by chemists
and physicists at five different Bavarian Universities and is funded with euro50 million for the period 2012-201647
The SolTech network covers all fields of research on solar energy use such as the conversion of solar energy
to electricity for immediate use and the conversion of solar energy into chemical energy for storage and future
use
France - Alternative Energies and Atomic Energy Commission (CEA)48
CEA is a public government-funded research organisation active in four main areas low-carbon energies
defence and security information technologies and health technologies The CEA is the French Alternative
Energies and Atomic Energy Commission The CEA had a total budget of euro43 billion and around 16000
permanent staff On photovoltaic cell technology CEA is collaborating with Photowatt Pechiney and Appolon
Solar and on photovoltaic modules and systems with TOTAL Energie
UK - University of East Anglia (UEA) Cambridge and Leeds
A specific research programme by the UEA on the creation of hydrogen with energy derived from
photocatalysts designed to replicate photosynthesis is funded by the Biotechnology amp Biological Sciences
Research Council (BBSRC) The total amount of funding is approximately euro1 million (pound800000)49
432 Research investments outside Europe
The main research programmes and consortia discussed are JCAP (US) SOFI (US) ARPChem (Japan)
AnApple (Japan) and KCAP (Korea) In contrast to Europe the use of energy innovation hubs ie major
integrated research centres drawing together researchers from multiple institutions and varied technical
backgrounds is more common in the US and Asia Also partnerships between the government academia
and industry seem to be more common in those areas than they are in Europe The idea of developing new
energy technologies in innovation hubs is very different compared to the approach of helping companies scale
up manufacturing through grants or loan guarantees50
The information on the budgets from the large
networks is generally available
44
httpwwwcecmpgdeinstitutdaten-faktenhtml 45
httpswwwbiotechnologiedeBIONavigationENrootdid=164934htmlview=renderPrint 46
httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf 47
httpwwwsoltech-go-hybriddeabout-soltech 48
httpenglishceafrenglish-portal 49
httpwwwwiredcouknewsarchive2013-0122artificial-photosynthesis 50
httpswwwtechnologyreviewcoms429681artificial-photosynthesis-effort-takes-root
72
Funding of AP research programmes and research consortia
Japan ndash ARPChem
In Japan the Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology (MEXT) launched a large artificial photosynthesis project that will tackle the study for
the coming decade between 2012 and 2021 with an expected budget of about euro122 million (15 billion yen)
The main organisation to conduct the project is the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem)51
Japan ndash AnApple
All Nippon Artificial photosynthesis Project for Living Earth (AnApple) is a five-year research programme
(2012-2017) joined by more than 40 Japanese leading scientific groups In this strong collaboration they aim
at achieving breakthroughs for the realisation of artificial photosynthesis AnApple hosted The International
Conference on Artificial Photosynthesis (ICARP)rdquo in 2014 and receives strong financial support52
from the
Ministry of Education Culture Sports Science and Technology
Korea ndash KCAP
The Korea Center for Artificial Photosynthesis (KCAP) at Sogang University was established in September
2009 through complementary and collaborative research with the Lawrence Berkeley National Lab (LBNL) in
the US to build the foundation for the realisation and commercialisation of artificial photosynthesis KCAP
receives a grant of euro385 million (50 billion won in 10 years) from the Ministry of Education Science and
Technology (MEST) through the National Research Foundation of Korea (NRF)
US - JCAP
JCAP (Joint Centre for Artificial Photosynthesis) was established in 2010 by the Department of Energy as one
of the Energy Innovation Hubs with a fund of euro108 million ($122 million) for five years Additional funding for
the next five years amounts to euro67 million ($75M) but is still subject to congressional appropriation53
JCAP
is the largest artificial photosynthesis research programme in the world There are 190 persons linked to the
research programme
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years SOFI (Solar Fuels Institute) is focused on light capture
water splitting CO2 catalysis and photoelectrochemical cells SOFI relies on a community of member
institutions and individual supporters who believe strongly in a clean energy future54
The solar fuel created
using catalysts and technology shared by global members of SOFI is funded by crowdfunding campaigns
(Kickstarter campaign) Furthermore SOFI partnered with TSRC to raise by means of a bold campaign one
billion dollars over the next ten years to fund the research55
Funding of other AP initiativesprojects
US ndash Plug-and-play photosynthesis CAPP (combining algal and plant photosynthesis)
Three UKUS-funded projects received funding to improve photosynthesis The three research teams (each
comprised of scientists from the United Kingdom and the United States) have been awarded a second round
of funding to build on their research findings and develop new ways to improve photosynthesis Projects
include plug-and-play photosynthesis by the Arizona State University Multi-level Approaches for Generating
Carbon Dioxide (MAGIC) led by the Pennsylvania State University and Combining Algal and Plant
Photosynthesis (CAPP) led by the Stanford University received in 2014 a new round of funding of euro44 million
51
httpwwwmetigojpenglishpress20121128_02html 52
httpartificial-photosynthesisnetICARP2014scopehtml The concrete funding figures are not available 53
httpenergygovarticlesenergy-department-provide-75-million-fuels-sunlight-hub) httpsolarfuelshuborgresearchoverview 54
httpwwwsolar-fuelsorgdonate 55
httpstelluridescienceorgsofi-brochurepdf
73
(pound5 million) in total over three years from the Biotechnology and Biological Sciences Research Council
(BBSRC) and the National Science Foundation56
Israel ndash Projects funded by AERI
AERI is providing a pool of funds to try out new ideas and jump-start research projects that are not applicable
for conventional grants Since 2006 already 8 cycles of AERI-funded projects took place Projects under the
20132014 cycle include lsquoNew Options for Solar Energy Conversion to Biofuel and Electricity ndash Biofuels ndash
Photovoltaics and Opticsrsquo57
Funding is provided by the Canadian Center for Alternative Energy Research the
Helmsley Energy Program the Helmsley Charitable Trust (providing euro13 million ($15 million) over three
years) the Burk Fund for Alterative Energy Studies the Eisenberg Foundation and individuals58
China ndash Funding of the Dalian National Laboratory for Clean Energy
The Dalian National Laboratory for Clean Energy was established in 2011 The investments into this lab
amount to more than euro40 million (289 million RMB) a year (over 50 of annual research of the Dalian
University of Technology within which the laboratory functions)59
In addition to this laboratory Haldor Topsoe
opened an RampD Center60
at the same university to join forces in the research of clean energy Haldor Topsoe
is also going to sponsor RampD projects however the size of the investments is not revealed Prior to that
Topsoe already established a scholarship with a value of around euro400 a month (3000 RMB)61
44 Strengths and weaknesses
This section presents the analysis of the strengths and weaknesses of the research community in the field of
artificial photosynthesis The findings are based on the results of the survey conducted during March 2016
and are supplemented by desk research Firstly we outline the main strengths and weaknesses with regard to
global AP research Secondly the strengths and weaknesses of the European community compared to the
non-European community are presented
441 Strengths and weaknesses of AP research in general
Table 48 below summarises the strengths and weaknesses of research in AP taking a global perspective
Table 48 Summary of strengths and weaknesses of research globally
Strengths Weaknesses
A diverse community of researchers bringing together
experts in chemistry photochemistry electrochemistry
physics biology catalysis etc
Researchers focus on all technology pathways in AP
Existing research programmes and roadmaps in AP
Available financial investments in several countries
Limited communication cooperation and collaboration
at an international level
Limited collaboration between academia and industry
at an international level
Transfer from research to practical applications is
challenging
Note International level refers not only to EU countries but all around the world
Globally there is a wide variety of RampD institutes (and researchers) focused on AP forming a diverse
community of researchers Research in AP requires interdisciplinary teams The experts working together
on this topic often have backgrounds in chemistry physics and biology
56
httpwwwbbsrcacuknewsfood-security2014140602-pr-bbsrc-and-nsf-funding-photosynthesis 57
httpwwwweizmannacilAERIresearch 58
httpwwwweizmannacilresdevsitesweizmannacilresdevfilesenergy_booklet_lo_res_2012pdf 59
httpwwwnaturecomnews2011111031fullnews2011622html 60
httpwwwtopsoecomnews201602topsoe-establishes-rd-center-dalian-institute-chemical-physics-china 61
httpwwwdnlorgcnshow_enphpid=776
74
A diverse community of researchers is focusing on all the pathways in AP which ensures diverse
approaches an exchange of different views a dynamic research community and avoids lock-ins into one
specific pathway This broad and inclusive research approach is the best way to maximise the probability of
AP research being successful in developing efficient and commercially viable AP processes
Several countries have dedicated programmes andor roadmaps to the topic of AP The US Japan the
Netherlands and South Korea have invested in large-scale interdisciplinary research programmes (specifically
on solar fuels) China and Japan have dedicated centres for renewable energy research where solar fuels are
an area of substantial effort For example the Department of Energy of the US sponsors Energy Innovation
Hubs aiming to overcome scientific barriers to develop a complete energy system with the potential to turn into
a transformative energy technology62
One of such innovation hubs is the Joint Center for Artificial
Photosynthesis established in 2010 In the Netherlands a public private partnership was established to form
BioSolar Cells of which one of the main focal themes is AP Globally several hundreds of millions of euros
are being spent this decade on AP research and this research seems to be intensified further
Despite the intensification of global research efforts the communication cooperation and collaboration at
an international level remains limited Many AP consortia link different research groups but operate only at
a national level63
Yet a higher level of institutionalised international or global cooperation going beyond
international academic conferences could spur innovative research in the field and enhance knowledge
exchange and spill-overs A number of survey respondents indicated that the lack of coordination
communication and cooperation at an international level is one of the main weaknesses in current AP-related
research activities
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research
including research on artificial photosynthesis In Japan the industry is involved in AP research to a greater
degree64
Nevertheless although companies are participating in local consortia such as ARPChem and
BioSolar Cells there seems to be a lack of cooperation between academia and industry at an
international level
The transfer of research to industrial application in artificial photosynthesis remains challenging In order
to attract the attention of the private sector artificial photosynthetic systems must be cost-effective efficient
and durable An active involvement of industrial parties could help bringing research prototypes to
commercialisation This step towards commercialisation requires a sufficient critical mass and funding
however which cannot be borne by a single country
442 Strengths and weaknesses of AP research in Europe
Table 49 below summarises the strengths and weaknesses of research in artificial photosynthesis in Europe
as compared to non-European research
62
httpscienceenergygovbesresearchdoe-energy-innovation-hubs 63
The only exception is AMPEA with its pan-European reach 64
The Korean Centre for Artificial Photosynthesis (KCAP) collaborates with a number of companies Toshiba and Panasonic made some advances in artificial photosynthesis research (httpasianikkeicomTech-ScienceScienceHow-artificial-photosynthesis-could-cut-emissions) ARPChem has a few corporate members on board (httpwwwmetigojpenglishpress2012pdf1128_02bpdf)
75
Table 49 Summary of strengths and weaknesses of research in Europe
Strengths Weaknesses
A strong diverse community of researchers
RampD institutions research capacity and facilities
Existing research programmes and roadmaps for AP in
several MS
Available financial investments in MS
Ongoing and conducted FP7 projects at EU level
Close collaboration of research groups in consortia
Limited communication cooperation and collaboration at
a pan-European level
Limited collaboration between academia and industry
within Europe
Limited funding mostly provided for short-term projects
focusing on short-run returns
National RampD efforts in AP are scattered
Europe has a diverse research community working on artificial photosynthesis research covering all the
technology pathways Europersquos universities have many highly educated researchers in the fields of chemistry
physics and biology at their disposal There is a solid foundation of RampD institutions research capacity
and facilities such as specialised laboratories which work together at a national level
National research programmes and roadmaps for AP exist in several Member States an indication that
AP research is on the agenda of European governments65
Therefore also financial investment for AP
research is available in several MS such as in Germany66
and other countries European-level
collaboration between different research groups and institutes from different countries has been achieved in
the framework of FP7 projects67
as well as predecessors of it
Five main consortia in Europe ensure that research groups and research institutes are collaborating
closely68
such as in Sweden where the Consortium for Artificial Photosynthesis (CAP) is active and in the
Netherlands where researchers work in close cooperation within the BioSolar Cells consortium Nevertheless
there is still much room to expand globally as well as within Europe most consortia are operating within and
collaborating with research groups in countries where they are based themselves
The level of cooperation and collaboration at a pan-European level hence seems to be limited There
are a few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7 projects
but many research groups are operating locally and are funded by national governments Several survey
respondents reported a low degree of collaboration among different research groups which typically results in
a duplication of efforts and a lack of generalised standards Synergies which could potentially boost research
in artificial photosynthesis are being overlooked Creating for example a communication platform to facilitate
the exchange among researchers could more easily promote the development of knowledge and increase the
speed of discovery and exploitation of new robust (effective and durable) photocatalysts innovative processes
and devices etc Moreover another indicated weakness is the lack of collaboration between already existing
and ongoing projects
While industrial companies are present in a few consortia there is limited collaboration between European
academia and industry Improved collaboration could result in the development of more advanced AP
processes and AP process devices and it might improve the probability of APrsquos successful commercialisation
in the foreseeable future
65
For example Strategic Energy Technology (SET) Plan European Biofuels Technology Platform (EBTP) and European Industrial Bioenergy Initiative (EIBI) JCAP scientific programme For more information please refer to Deliverable 1 Chapter 32
66 By now research funded by the government of Germany in the field of artificial photosynthesis amounts to euro 42 million (httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf)
67 See Deliverable 1
68 httpswwwleopoldinaorgenpolicy-adviceworking-groupsartificial-photosynthesis
76
The long-term focus of AP research is a hurdle for both gaining cooperation with industry and for obtaining
funding Compared to that of its non-European counterparts European funding focuses on the short
term69
While in the USA and Japan funding is dedicated for about 5-10 years European parties often get
funding for about 4 years at the most Although several MS also have dedicated RampD programmes focusing
on AP the amounts provided by non-European counterparts exceed those of the European70
Furthermore
these national programmes are fragmented ie lacking a common goal and perspective hence the funding
of research is also fragmented and scattered71
The European community of researchers could benefit
from an integrated programme which clearly indicates research goals and objectives In addition a common
funding scheme set up to support fundamental research in artificial photosynthesis and to promote
collaboration with industry could advance the research in artificial photosynthesis
A number of survey respondents indicated that there is currently little focus of EU-funded research on
technologies with low TRL within H2020 At the moment there is a strong emphasis on the projects and
technologies which already have a rather high TRL expecting returns in the near future while research in the
area of low TRL technologies requires some attention and funding Several respondents mentioned that there
exist still quite some barriers regarding the design of low-cost materials with low TRL and with higher stability
and activity (eg performance of devices when it comes to a discontinuous supply of energy)72
45 Main industrial actors active in AP field
451 Industrial context
The idea behind artificial photosynthesis is that solar fuels could solve worldwide energy problems by using
water and carbon dioxide and converting them into the fuels we need Artificial photosynthesis can convert
sunlight directly into chemical fuels which makes it possible to harvest and store energy However there are
still many obstacles to make this technology commercially viable Only if artificial photosynthesis can be
provided efficiently stably safely and cheaply will it be beneficial for the public This means inter alia that an
efficient light absorber and catalysts need to be created to convert sunlight into fuel Even though there are
rapid developments in the field of artificial photosynthesis there are many obstacles to overcome in order to
reach mass production Currently the positioning of the fields of artificial photosynthesis and solar fuels is at
around a 3 on the technology readiness level
452 Main industrial companies involved in AP
At the moment the number of companies active in the field of AP is limited Based on our analysis of the main
AP actors in the industry only several tens of companies appear to be active in this field Moreover industrial
activity is limited to research and prototyping as viable AP technologies have not (yet) been commercialised
35 companies active in the field of AP have been identified comprising 16 European companies and 19 non-
European companies (Table 410) Seven of these are in Germany eight in the Netherlands eight in Japan
and 10 in the US The following table summarises the countries in relation to one or more of the technology
pathways
69
Already in 2013 it was indicated that much of public funding of basic AP research remains short term For more information see Thomas FaunceStenbjorn Styring Michael R Wasielewski Gary W Brudvig A William Rutherford et al (2013) Artificial Photosynthesis as a Frontier Technology for Energy Sustainability Energy amp Environmental Science Issue 4 2013
70 A number of respondents indicated that the available funding is not sufficient to finance research facilities and equipment
71 This weakness is indicated by several respondents
72 This is also mentioned as one of the areas of attention in Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press)
77
Table 410 Overview of the size of the industrial community number of companies per pathway
Country Synthetic biology amp
hybrid systems
Photoelectrocatalysis Co- electrolysis Total number of
companies
European companies
France 1 1 0 1
Germany 2 2 0 4
Italy 0 1 0 1
Netherlands 3 4 1 8
Switzerland 0 1 0 1
Total 6 9 1 15
Non-European companies
Japan 0 8 0 8
Saudi Arabia 0 1 0 1
Singapore 0 0 1 1
US 3 2 4 8
Total 3 11 5 19
Note a company can be active in multiple technology pathways
Source Ecorys
With respect to the industry largely the same countries stand out as in the research field namely Japan the
US and north-western Europe The industry in Japan appears to have the most intensive research activities
in AP as several large Japanese multinationals have set up their own AP RampD laboratoriesresearch
departments
With respect to the three technology pathways (i) synthetic biology amp hybrid systems (ii) photoelectrocatalysis
and (iii) co-electrolysis we have observed that most industrial (research) activity is being performed
concerning photoelectrocatalysis (19 companies) although there are also companies active in the two other
pathways
We have also identified a number of companies active in the area of carbon capture and utilisation that might
potentially be involved in the research of artificial photosynthesis
453 Companies active in synthetic biology amp hybrid systems
The pathway involving synthetic biology amp hybrid systems is still at an early stage on the TRL scale (TRL 1-2)
The challenges industries face relate mostly to efficiency obstacles Enzymes and proteins need to be
modified by genetic engineering Another barrier relates to the fact that the modifications and protein
production are still very time-consuming in terms of cell growthprotein purification Furthermore it is
necessary to improve protein stability and solubility by rational design directed evolution and modifying
sample conditions since currently proteins are unstable It would probably take about 10-20 years until
technologies reach TRL 7
The companies involved in this pathway range from chemical and oil-refining companies companies working
on bacteria companies producing organic innovative catalysts to others The following table lists the
organisations identified within this pathway
78
Table 411 Organisations in synthetic biology amp hybrid systems
Country Organisation (in EN)
France PhotoFuel
Germany Evonik Industries AG
Germany Brain AG
Italy Hysytech
Netherlands Biomethanol Chemie Nederland BV
Netherlands Photanol BV
Netherlands Tendris Solutions
Netherlands Everest Coatings
US Joule Unlimited
US Phytonix
US Algenol
Source Ecorys
Chemical and oil-refining companies
Biomethanol Chemie Nederland BV a Dutch company that produces and sells industrial quantities of high
quality bio-methanol focusing on synthetic biology amp hybrid systems is also a partner of the BioSolar Cells
programme The BioSolar Cells programme focuses its research on artificial photosynthesis photosynthesis in
cellular systems and photosynthesis in plants
Companies working on bacteria
Another group of companies in the pathway of synthetic biology amp hybrid systems focus on CO2 to fuel
processes that use cyanobacteria to convert CO2 into targeted fuels or chemicals (biological conversion)
Examples of such companies are Joule Unlimited Phytonix and Algenol all based in the US Algenol is
commercialising its patented algae technology platform for the production of ethanol using proprietary algae
sunlight carbon dioxide and saltwater The Dutch company Photanol uses cyanobacteria to turn CO2 into
certain predetermined products
Companies producing organic innovative catalysts
Many of the smaller companies currently active in developing AP originate from a specific research group or
research institute and focus on specific AP process steps andor process components Some companies
focus on the further development of both chemical and organic innovative catalysts which are earth-abundant
non-toxic and inexpensive Brain AG (Germany) is an example of such a company
Other companies
Hysytech is an Italian company experienced in technology development and process engineering applied to
the design and construction of plants and equipment for fuel chemical processing energy generation and
photoelectrocatalysis Hysytech is involved in an FP7 project to develop a fully artificial photoelectrochemical
device for low temperature hydrogen production
Other companies in the field of synthetic biology amp hybrid systems are Tendris Solutions (Netherlands) and
Everest Coatings (Netherlands) involved in the EET-Kiem project which focused on increasing the
absorption of visible light in the TiO2 photocatalyst by incorporating other elements in the structure and to
construct a photoelectrochemical reactor Photofuel in France and Phytonic in the US focus on synthetic
biology amp hybrid systems and photoelectrocatalysis Evonik Industries AG invests in synthetic biology amp
hybrid systems as well as carbon capture technologies which convert waste CO2 into products and fuels
79
454 Companies active in photoelectrocatalysis
The pathway of photoelectrocatalysis is relatively low on the TRL scale as well (TRL 1-4)
Photoelectrocatalysis would make it possible to use photovoltaic cells that absorb photons to facilitate water
splitting Research on photoelectrocatalysis using photoelectrochemical cells in particular is still at a very early
stage
Technologies pertaining to the photoelectrocatalysis pathway are not yet commercially viable with the main
challenges relating to the design of devices that are efficient stable and durable Further potential obstacles to
be taken into account relate to the incorporation of these technologies with other technologies that can
generate fuel molecules other than hydrogen
Most companies are involved in this pathway ranging from automotive manufacturers and electronic
companies to chemical and oil-refining companies The following table lists the organisations identified within
this pathway
Table 412 Organisations in the field of photoelectrocatalysis
Country Organisation (in EN)
France PhotoFuel
Germany Bauhaus Luftfahrt eV (Bauhaus Luftfahrt Research)
Germany ETOGAS
Italy Hysytech
Japan Toyota (Toyota Central RampD Labs)
Japan Honda (Honda Research Institute - Fundamental Technology Research Center)
Japan Mitsui Chemicals
Japan Mitsubishi (Mitsubishi chemicals Setoyama Laboratory)
Japan Sumitomo Chemicals (Energy amp Functional Materials Research Laboratory)
Japan INPEX Corporation
Japan Toshiba (Corporate Research and Development Center)
Japan Panasonic (Corporate Research and Development Center)
Netherlands InCatT BV
Netherlands Shell (Shell Game Changer Programme)
Netherlands Hydron
Netherlands LioniX BV
Saudi Arabia Saudi Basic Industries Corporation
Switzerland SOLARONIX SA
US HyperSolar
Source Ecorys
Companies in the automotive sector
Several automotive manufacturers are active in the field of AP mostly relating to the field of
photoelectrocatalysis In 2012 Honda opened a hydrogen station in Saitama Japan that converts sunlight
into hydrogen that could be used to power fuel-cell electric vehicles The station is focusing on
photoelectrocatalysis and turning sunlight into hydrogen via a high-pressure water electrolysis system that
was developed by Honda itself Since then there seems to be little activity from Honda73
73
httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
80
Figure 44 Hondarsquos sunlight-to-hydrogen station
Source httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
Toyota succeeded (in 2011) to generate organic compounds via artificial photosynthesis without using any
external energy andor material sources The system is focused on producing formic acid (which could be
used as a raw material in industry) In February 2016 Toyota Central RampD Labs announced that they
achieved the worldrsquos highest energy conversion efficiency rate of 46 with artificial photosynthesis using
water and carbon dioxide as raw materials and sunlight as energy to produce useful materials Toyota is also
researching new chemical reactions to generate more valuable organic compounds as a final product such as
methanol Toyota is primarily focused on photoelectrocatalysis The companyrsquos 2020 goal is to complete basic
testing for the creation of primary CO2-absorbing materials (material or fuel)74
Electronic companies
In addition to car manufacturers also electronic companies are involved in photoelectrocatalysis In December
2014 Toshiba announced its focus on producing a catalyst made of gold The company indicated that they
found a way to modify gold at the atomic level using nanotechnology which allows carbon dioxide to change
into other compounds at a lower voltage (with a record of 15 energy efficiency rate)75
In September 2015 Toshiba made public that the company developed a prototype of a new highly efficient
molecular catalyst (consisting of an imidazolium salt) that converts carbon dioxide into ethylene glycol without
producing other and unwanted by-products Most artificial photosynthesis technologies use a two-electron
reduction conversion process producing carbon monoxide and formic acid Others can achieve direct multi-
electron reduction but tend to produce many by-products and their separation can be problematic Toshibas
new molecular catalyst converts carbon dioxide into ethylene glycol via multi-electron reduction The long-term
goal of Toshibarsquos research work is to develop a technology compatible with carbon dioxide capture systems
installed at facilities such as thermal power stations and factories utilising carbon dioxide to provide (storable)
energy To this end Toshiba focuses on photoelectrocatalysis and further improvement of the conversion
efficiency by increasing catalytic activity and aims at practical implementation in the 2020s76
Panasonics artificial photosynthesis system is also focused on photoelectrocatalysis in particular on highly
efficient CO2 conversion which can utilise direct sunlight or focused light In 2012 Panasonic found that a
nitride semiconductor has the capability to excite the electrons with enough high energy for the CO2 reduction
reaction to take place Nitride semiconductors have attracted attention for their potential applications in highly
74
httpwwwtytlabscom and httpswwwasiabiomassjpenglishtopics1603_01html 75
httpwwwjapantimescojpnews20150412nationalscience-healthlab-photosynthesis-begins-to-bloomVw1YZP5f3IV 76
httpswwwtoshibacojprdcrddetail_ee1509_01html
81
efficient optical and power devices for energy saving However its potential was revealed to extend beyond
solid devices more specifically it can be used as a photoelectrode for CO2 reduction By making a devised
structure through the thin film process for semiconductors the performance as a photoelectrode has greatly
improved77
In September 2014 Panasonic Corporation managed to achieve a conversion efficiency rate of
0378
and not long after that the company announced to having achieved the first formic acid generation
efficiency of approximately 10 as of November 201479
According to Panasonic the key to achieving an
efficient artificial photosynthetic system lies in improved photoelectrodes and oxidation-reduction electrodes
Chemical and oil-refining companies
The developments with respect to solar fuels are also being supported by several chemical and oil-refining
companies Artificial photosynthesis has been an academic field for many years However in the beginning of
2009 Mitsubishi Chemical Holdings reported to be undergoing its own artificial photosynthesis research by
using sunlight water and carbon dioxide to create the carbon building blocks from which resins plastics and
fibres can be synthesisedrdquo80
In 2014 Mitsubishi established the research organisation Setoyama Laboratory
The Laboratory focuses on the development of artificial photosynthesis for chemical processes which is the
synthesis of raw materials such as ethylene propylene butenes etc by means of solar hydrogen obtained by
catalytic water splitting under visible light and CO2 emitted at a plant site81
The laboratory is also participating
in the ldquoArtificial Photosynthetic Chemical Processrdquo project (denoted ldquoARPChemrdquo) granted by NEDO (New
Energy Development Organization) In this project the following three programmes are conducted through
collaboration with academia and industry
1 Design of a photo semiconductor catalyst for water splitting
2 A membrane separation system for H2 from gas mixtures composed of H2 and O2 and
3 A catalytic process for the synthesis of lower olefins from H2 and CO2
The Japanese chemical companies Sumitomo chemicals and Mitsui Chemicals focusing on carbon
capture and photoelectrocatalysis are also participating in the ARPChem programme Sumitomo has its
own Energy amp Functional Materials Research Laboratory and is conducting research and development in a
broad range of fields Mitsui created the Mitsui Chemicals Catalysis Science Award and the Mitsui Chemicals
Catalysis Science Award of Encouragement in order to award recognition to national and international
researchers that have made substantial contributions to the field of catalysis science In 2014 it was the fifth
time that Mitsui has given these awards
Royal Dutch Shell cooperated with Bauhaus Luftfahrt in the EU-funded Solar-Jet project (2011-2015) in the
area of photoelectrocatalysis aimed at demonstrating an innovative process technology using concentrated
sunlight to convert carbon dioxide and water into synthesis gas (syngas) The syngas a mixture of hydrogen
and carbon monoxide is ultimately converted into kerosene by means of the commercial Fischer-Tropsch
technology With the first ever production of synthesised ldquosolarrdquo jet fuel the SOLAR-JET project has
successfully demonstrated the entire production chain for renewable kerosene obtained directly from sunlight
water and carbon dioxide (CO2)82
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University (US)
SOFI leads a global consortium that brings together universities from Rutgers University in New Jersey to
Uppsala University in Sweden83
SOFI focuses on both the water-splitting process (production of hydrogen)
and the CO2 reduction process (the reduction of carbon dioxide to carbon monoxide which in combination
77
httpnewspanasoniccomglobalpressdata201207en120730-5en120730-5html 78
httpswwwasiabiomassjpenglishtopics1603_01html 79
httpwwwpanasoniccomglobalcorporatetechnology-designtechnologyphotosynthesishtml 80
httpwwwdigitalworldtokyocomindexphpdigital_tokyoarticlesmanmade_photosynthesis_looking_to_change_the_world 81
httpwwwmcrccojpenglishrdsetoyama_laboratoryhtml 82
httpwwwsolar-jetaeropagepostsartsunlight-to-jet-fuel-european-collaboration-solar-jet-for-the-first-time-demonstrates-the-entire-production-path-of-ldquosolarrdquo-kerosene-4php
83 httpappsnorthbynorthwesterncommagazine2015springsofi
82
with hydrogen can be processed into eg methanol or synthetic gasoline) Total is also a partner of the
BioSolar Cells programme
INPEX Corporation is a Japanese oil company established in February 1966 as North Sumatra Offshore
Petroleum Exploration Co In addition to Mitsubishi Chemicals Sumitomo Chemicals and Mitsui Chemicals
INPEX also participates in the ldquoJapan Technological Research Association of Artificial Photosynthetic
Chemical Processrdquo (ARPChem) programme and engages in RampD projects with the aim to produce chemical
products like plastics and hydrocarbon fuel from photochemical catalysis INPEX Corporation is focused on
photoelectrocatalysis
Other companies
Other companies include Etogas (Germany) which develops builds and selects Power-to-Gas plants and
products related to Power-to-Hydrogen Power-to-SNG and Hydrogen-to-SNG LnCatT BV (Netherlands)
Hydron (Netherlands) Saudi Basic Industries Corporation (Saudi Arabia) and Hyper Solar () all focus on
photoelectrocatalysis LioniX BV (Netherlands - photoelectrocatalysis) and Solaronix SA (Switzerland -
photoelectrocatalysis) are focused on the further development of photoelectrochemical cells Hysytech and
Photofuel are in addition to the first pathway also involved in the second
455 Companies active in co-electrolysis
Even though co-electrolysis is the pathway at the highest levels of technical readiness compared to the other
two pathways not many companies are involved in it There are three electrolyser types capable of producing
hydrogen gas eg alkaline electrolysis polymer electrolyte membrane electrolysis and solid oxide electrolysis
cells (SOECs) Multiple designs are commercialised although SOECs using Fischer-Tropsch synthesis are
not yet commercially viable The companies involved in this pathway are mainly from the US Industries
combine co-electrolysis and the field of carbon capture Fuel cell products are used in the automotive
telecom defenceaerospace and consumer product sectors
The following table summarises the organisations in the field of co-electrolysis
Table 413 Companies in co-electrolysis
Country Organisation (in EN)
Netherlands Shell (Shell Game Changer Programme)
Singapore Horizon Fuel Cell Technologies
US Catalytic Innovations
US Opus 12
US LanzaTech
US Proton onsite
Source Ecorys
Companies include Proton onsite (US ndash PEM electrolysis) which manufactures hydrogen nitrogen and zero
air generators in a safe reliable and cost-effective way Horizon Fuel Cell Technologies (Singapore)
focuses on commercially viable fuel cells starting by simple products which need smaller amounts of
hydrogen The technology platform of horizon fuel cell technology is focused on three main topics PEM fuel
cell systems hydrogen supply and hydrogen storage Catalytic Innovations (US) Opus 12 (US) Lanzatech
(US) and Shell (NL) are also involved in the second pathway
83
456 Companies active in carbon capture and utilisation
The technology in the carbon capture and storage pathway can capture up to 90 of the CO2 and allows for
the separation of carbon dioxide from gases produced in electricity generation and industrial processes by
means of combustion capture and oxyfuel combustion The most advanced technologies are at TRL 7 eg
carbon capture in a coal plant
The following table shows the organisations active in the field of carbon capture and utilisationre-use
Table 414 Organisations active in carbon capture and utilisation
Country Organisation (in EN)
Denmark Haldor Topsoe
Germany Evonik Industries AG
Germany Siemens (Siemens Corporate Technology CT)
Germany Sunfire GmbH
Germany Audi
Switzerland Climeworks
UK Econic (Econic Technologies)
Canada Carbon Engineering
Canada Quantiam
Canada Mantra Energy
Iceland Carbon Recycling International
Israel NewCO2Fuels
Japan Mitsui Chemicals
US Liquid light
US Catalytic Innovations
US Opus 12
US LanzaTech
US Global Thermostat
Source Ecorys
Twelve companies currently only focus on carbon capture and utilisation These companies are therefore
technically not considered to be companies involved in artificial photosynthesis However they can potentially
be involved in AP research in the future Such companies include automotive manufacturers as well as
electronics companies Five companies are involved in carbon capture and one of the pathways
Automotive manufacturers
Audi is working together with the American company Joule Unlimited in order to research and produce lsquoe-
ethanolrsquo Joule optimised a production process in which microorganisms are able to produce and excrete
either ethanol or alkanes from carbon dioxide (CO2) and sunlight Audi and Joule opened a joint
demonstration plant in September 2012 where e-ethanol is produced in transparent plastic tubes (see Figure
45)
84
Figure 45 Demonstration facility of Audi and Joule in Hobbs (New Mexico)
Source httpwwwbest-practicesfrost-multimedia-wirecomjoule2015
In January 2014 Audi e-ethanol underwent its first-ever test cycle in the pressure chamber and glass engine
showing that fewer pollutants are produced in the combustion of e-ethanol than is the case with bio-ethanol84
Since 2011 Audi has also been collaborating with Joule to produce e-diesel Finally in November 2014 Audi
opened a research facility in Dresden with project partners Climeworks and the start-up Sunfire in order to
produce its first batches of synthetic diesel combining two innovative technologies CO2 capture from the
ambient air (Climeworks) and the power-to-liquid process for the production of synthetic fuel (Sunfire)85
Currently Audi is investing in carbon capture and utilisation technologies
Electronics companies
Electronics companies such as Siemens are also investing in carbon capture technologies Developers at
Siemens Corporate Technology (CT) in Munich are currently active in the project CO2-to-value The challenge
of the project is to charge only carbon dioxide with electrons and not the surrounding water molecules
because the latter would merely result in the production of conventional hydrogen Specialists at the University
of Lausanne in Switzerland and materials scientists at the University of Bayreuth are working with Siemens to
develop catalysts on their behalf Siemens takes on a pragmatic approach by focusing on only one step in the
AP process They are not yet trying to capture light Instead they are centring their research activities on
activating CO2 and converting it into products such as (i) ethylene which the chemical industry needs for the
production of plastics (ii) methane the main component of natural gas and (iii) carbon monoxide which can
be used to produce fuels such as ethanol86
Other companies
Figure 46 illustrates the process of NewCO2Fuels (NCF) an Israeli company focused on carbon capture
This is a high-temperature-driven CO2- and water-dissociation process that produces syngas (a mixture of
CO and H2) from which various synthetic fuels and chemicals can be produced
In the short term NCF is focusing on the design and building of a first pilot plant as well as raising the
necessary funds for it
In the mid term NCF plans to offer its technology to the energy intensive industries such as the steel
gasification and glass industries to transform their CO2 waste streams into feedstock
In the long term NCFrsquos vision is to use solar energy to convert CO2 captured immediately from the
atmosphere into valuable products
84
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 85
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 86
httpwwwsiemenscominnovationenhomepictures-of-the-futureresearch-and-managementmaterials-science-and-processing-co2tovaluehtml
85
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels
Source httpwwwnewco2fuelscoilproduct8overview
Furthermore some companies focus on chemical or biological CO2-to-fuel production Examples of
companies that focus on direct (co-electrolysis) CO2 to fuels production are Carbon Recycling (Iceland) and
Econic (UK ndash carbon capture) The company Liquid Light (US ndash carbon capture) focuses on the
electrochemical conversion of CO2 to chemicals
Other companies involved in carbon capture are Global Thermostat (US) Quantiam (Canada) Carbon
Engineering (Canada) Evonik Industries AG (Germany) and Haldor Topsoe (Denmark) Besides co-
electrolysis Catalytic Innovations Opus 12 and Lanzatech are also involved in carbon capture Mitsui
Chemical is focusing on carbon capture as well as photoelectrocatalysis
457 Assessment of the capabilities of the industry to develop AP technologies
Although there is a lot of research activity going on in the field of AP both at the academic and industrial level
the technology is clearly not yet ready for commercialisation However concrete test facilities and prototypes
are being developed and solar fuels have already been produced at a laboratory scale The technology is not
yet sufficiently efficient in order to be able to compete with other technologies producing comparable
chemicals and fuels Finding catalysts which are on the one hand Earth-abundant non-toxic and inexpensive
and on the other hand sufficiently efficient seems to be the biggest challenge With respect to the
technological efficiency of the AP processes the main bottlenecks are light capture (whole spectrum) getting
a good photocurrent density and using these charge carriers efficiently87
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade In September 2014 Panasonic Corporation managed to achieve a conversion
efficiency rate of 03 becoming the first to exceed the rate of 02 for regular plants In November 2014
Toshiba reached 15 which was followed by 20 achieved by the Japan Technological Research
Association of Artificial Photosynthetic Chemical Process (ARPChem) in February 2015 In February 2016
Toyota Central RampD Labs Inc announced that they achieved the worldrsquos highest energy conversion
efficiency rate of 46 with artificial photosynthesis by developing a semiconductor substrates-using iridium
and ruthenium catalyst They succeeded in increasing the efficiency rate a hundred-fold (an efficiency rate of
004 had been in achieved by Toyota in 2011)88
Figure 47 summarizes these efficiency rate developments
Several companies (eg Toshiba) hint at achieving efficiency rates of 10 and the first practical applications
87
httpwwwosa-opnorghomearticlesvolume_24february_2013featuresartificial_photosynthesis_saving_solar_energy_for 88
httpswwwasiabiomassjpenglishtopics1603_01html
86
of AP in the 2020s ARPChem aims to achieve a 10 level of energy conversion efficiency in 2021 (the rate
at which the manufacturing of raw materials for chemicals becomes economically viable)89
Figure 47 Transition of energy conversion efficiency of artificial photosynthesis
Source httpswwwasiabiomassjpenglishtopics1603_01html
It can also be observed that the big industrial investors in AP technology (research) already built interesting
partnerships with research centres and new innovative start-upscompanies For example
Audi works together with the innovative company Joule Unlimited (US) on the development of biologically-
derived e-ethanol and e-diesel and also works together with start-up company Sunfire on the production
of synthetic diesel
Siemens works together with specialists at the University of Lausanne in Switzerland and at the University
of Bayreuth Germany on innovative catalysts
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University
(US) that works on the water-splitting and CO2 reduction process and
Mitsubishi is one of the five industrial partners in the Japanese ARPChem programme (2012-2021)
focusing on artificial photosynthesis research in which various Japanese universities will be involved
(including Waseda University and Tokyo University)
46 Summary of results and main observations
The aim of this report was to gain an understanding and a clear overview of the main European and global
actors active in the field of artificial photosynthesis This has been achieved by
Identifying the main European and global actors active in the field of AP
Providing an assessment of the current level of investments in AP technologies
Assessing the key strengths and weaknesses of the main actors and
Assessing the capabilities of the industry to develop and exploit the AP technologies
Fuelled by the globally perceived need to find a green non-polluting and emission neutral energy source for
the future there has been much development in the field of artificial photosynthesis and considerable progress
has been made In addition the emergence of multiple consortia and governmental programmes and
international conferences in the last 10-15 years suggest that there is a higher awareness of the potential of
89
httpwwwmitsubishichem-hdcojpenglishcsrdownloadpdf13_25pdf
87
AP and that further advances are necessary The analysis has shown that although there have been some
promising developments especially in collaboration with industry much remains to be done for AP
technologies and processes to become commercially viable Milestones which will spur the development and
commercialisation process of AP encompass increased global and industry cooperation and the deployment
of targeted large-scale innovation projects following the example of the US innovation hubs
A summary of the results of the analysis and the main observations concerning the research and industry
actors active in the field of artificial photosynthesis is presented below It should be noted that the academic
and industrial community presented in this report is not exhaustive and especially with increasing interest in
AP more actors are expected to become active in the field
Research community
In general we observe that AP research has been intensified during the last decade given the increasing
number of emerging networks and communities We identified more than 150 research groups on AP
worldwide out of which more than 60 are located in Europe Due to the interdisciplinary character of AP
research combines expertise from biology biochemistry biophysics and physical chemistry The development
of research networks and consortia facilitates collaboration between different research groups and enables
them to benefit from synergies We identified six consortia in Europe and five outside of Europe respectively
Almost all of them are based in a specific country attracting primarily research groups from that country Only
one consortium AMPEA launched by the European Energy Research Alliance is truly pan-European with a
range of members across the EU
Table 415 Summary of findings size of research community
Number of research groups
Total in Europe 113
Number of research groups per pathway
Synthetic biology amp hybrid systems 53
Photoelectrocatalysis 69
Co-electrolysis 25
Total outside Europe 77
Number of research groups per pathway
Synthetic biology amp hybrid systems 30
Photoelectrocatalysis 59
Co-electrolysis 14
Source Ecorys
With respect to the three technology pathways (synthetic biology amp hybrid systems photoelectrocatalysis and
co-electrolysis) we observed that almost 85 of the research activities worldwide are focused on the first two
pathways (about 34 on the first pathway and 50 on the second) whereas the third pathway attracts only
about 16 of the research communityrsquos attention Only the Dutch AP consortium BioSolar Cells specifically
focuses on co-electrolysis Other consortia like ARPChem in Japan collaborating with industry prefer to
research artificial photosynthesis via photoelectrochemical catalysis as this pathway is the most mature and
with the highest probability of successful commercialisation
The diversity of the scientists involved is the biggest strength of this global AP research community
Furthermore all of the existing technological pathways in AP are covered which avoids lock-ins into one
pathway and increases the probability of success for AP in general AP is on the research agenda of several
countries which is proven by the existence of dedicated programmes roadmaps and funds Globally several
hundreds of millions of euros are being spent this decade on AP research and these investments seem to be
intensifying further Major shortcomings encompass a lack of cooperation between research groups in
88
academia on the one hand and between academia and industry on the other A more technical challenge is
the transfer of scientific insights into practical applications and ultimately into commercially viable products
The AP sector in Europe exhibits some strengths in comparison to its non-European counterparts but also
some weaknesses Europersquos scientific institutions are strong and its researchers highly educated
Furthermore RampD institutions and research facilities are available providing a solid ground for research
Some individual MS have their own research programmes roadmaps and funds Nevertheless the investment
does not reach the amount of funds available in some non-European countries and is rather short-term in
comparison to that of its non-European counterparts Furthermore both the national research plans and their
funding seem fragmented and scattered lacking an integrated approach with common research goals and
objectives At the European level however collaboration has been successful within several ongoing and
conducted FP7 projects Close collaboration between research groups could also be achieved through the
establishment of consortia Apart from the pan-European consortium AMPEA collaboration between research
groups of different countries is limited the consortia are primarily country-based and attract mostly research
groups from that respective country Lastly the level of collaboration between academia and industry seems
to be more limited in Europe compared to that within the US or Japan
Industrial actors
At this moment the number of companies active in the field of AP is limited AP is still mainly at the laboratory
level Most pathways are still at level 1 or 2 of technology readiness (TRL) implying that research is still being
conducted and used to improve feasibility Only co-electrolysis is at a more advanced stage and most
methods are already commercially viable
Based on our analysis of the main AP actors in the industry only several tens of companies appear to be
active in this field Moreover the industrial activity is limited to research and prototyping as viable AP
technologies are not (yet) in commercial operation The pathways synthetic biology amp hybrid systems and
photoelectrocatalysis are still at the lowest levels of technology readiness Research within the
photoelectrocatalysis pathway is still at an early stage as well however PV devices (semiconductor devices
similar to the ones used in PEC devices) have already been successfully commercialised Co-electrolysis on
the other hand is a technology already available for a longer time period in this pathway various
technologies to convert water and DC electricity into gaseous hydrogen and oxygen are already
commercialised In contrast the technologies producing hydrocarbons by Fischer-Tropsch synthesis
converting for example CO2 H2O and syngas into hydrocarbon fuels are still at an earlier stage of
development Co-electrolysis is therefore at a 1-9 TRL having both already commercialised technologies as
well as the Fischer-Tropsch synthesis
In total we have identified and analysed 33 industrial actors active in the field of AP 15 European and 18 non-
European industrial actors With respect to the industry largely the same countries stand out as in the
research field namely Japan the US and north-western Europe The industry in Japan appears to have the
most intensive research activities in AP as several large Japanese multinationals have set up their own AP
RampD laboratoriesresearch departments With respect to the three technology pathways we can observe that
most industrial (research) activity is being performed concerning photoelectrocatalysis
89
Table 416 Summary of findings size of industrial community
Number of companies
Total in Europe 15
Number of companies per pathway
Synthetic biology amp hybrid systems 6
Photoelectrocatalysis 9
Co-electrolysis 1
Total outside Europe 18
Number of companies per pathway
Synthetic biology amp hybrid systems 3
Photoelectrocatalysis 11
Co-electrolysis 5
Source Ecorys
The main hurdles in the synthetic biology amp hybrid systems pathway relate to the improvement of efficiency
and protein production speeds as well as stability and solubility by rational design With respect to the
technological efficiency of the AP processes relating to photoelectrocatalysis the main bottlenecks are light
capture (whole spectrum) obtaining a good photocurrent density and using these charge carriers efficiently
Co-electrolysis is mainly facing challenges to increase the lifetime of the devices to create concept on a
megawatt scale to search for substitution of noble metal catalysts and to develop technologies that are
capable of supplying the electricity required Furthermore some methods are still at a low TRL like the
Fischer-Tropsch synthesis Finding catalysts which are Earth-abundant non-toxic inexpensive and
sufficiently efficient remains a huge challenge To this end more public and private funding is needed
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade For example between 2011 and 2016 Toyota Central RampD labs made a significant
leap forward from an efficiency rate of 004 towards an efficiency rate of 46 Furthermore several
industrial actors (including Toshiba and ARPChem) have hinted at being able to achieve efficiency rates of
10 and the first practical applications of AP in the 2020s When academia are able to overcome the main
barriers with respect to AP the TRL will increase and the interest in AP from the industries will rise More
interest from the industries is necessary in order to push AP on the market and making it an economically
viable alternative renewable energy source
91
5 Factors limiting the development of AP technology
The overall concept followed in this study is to assess a number of selected ongoing research technological
development and demonstration (RTD)initiatives andor technology approaches implemented by European
research institutions universities and industrial stakeholders in the field of AP (including the development of
AP devices)
Seven AP RTD initiatives have been identified for the assessment of ldquolimiting factorsrdquo addressing the three
overarching technology pathways synthetic biology amp hybrid systems photoelectrocatalysis of water (water
splitting) and co-electrolysis (see Table 51)
The authors are confident that through the assessment of these selected European AP RTD initiatives a good
overview of existing and future factors limiting the development of artificial photosynthesis technology (in
Europe) can be presented However it has to be noted that additional AP RTD initiatives by European
research institutions universities and industrial stakeholders do exist and that this study does not aim to prove
a fully complete inventory of all ongoing initiatives and involved stakeholders
Table 51 Overview of the selected AP research technological development and demonstration (RTD) initiatives
AP Technology
Pathways AP RTD initiatives for MCA
Synthetic biology amp
hybrid systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Biocatalytic conversion of CO2
into formic acid ndash Bio-hybrid
systems
Photoelectrocatalysis
of water (light-driven
water splitting)
Direct water splitting with bandgap absorber materials and
catalysts
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
a) Direct water splitting with III-
V semiconductor ndash Silicon
tandem absorber structures
b) Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Co-electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
Electrolysis cells for CO2
valorisation ndash Industry
research
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges
Until today much progress has been made in the development of artificial photosynthetic systems
However a number of significant scientific and technological challenges remain to successfully scale-up
existing laboratory prototypes of different AP technology approaches towards a commercial scale
In order to ensure that AP technologies become an important part of the (long-term) future sustainable
European and global energy system and additionally provide high-value and low carbon chemicals for
industrial applications AP based production systems need to be
Efficient so that they utilise as much sunlight as possible to produce fuels andor chemicals The larger
the fraction of sunlight that can be converted to chemical energy the fewer materials and less land would
be needed for AP devices A target efficiency of about 10 (for AP based fuel production) is an initial goal
This is about ten times the efficiency of natural photosynthesis however it should be noted that AP
92
laboratory prototype devices with solar-to-hydrogen efficiencies of 5 and more have already been
developed
Durable so that AP systems can convert a lot of energy in their lifetime relative to the energy required for
the production and installation of the devices This is a significant challenge because some materials
degrade quickly when operated under the special conditions of illumination by discontinuous sunlight
Cost-effective meaning the raw materials needed for the production of the AP devices have to be
available at a large scale and the produced fuels andor chemicals have to be of commercial interest
Resource-efficient so that they minimise the use of rare and expensive raw materials (taking into
account trade-offs between material abundancy cost and efficiency)
Today significant improvements with respect to cost-efficiency lifetimedurability energy efficiency and
resource use are still required for all existing AP technology approaches
Table 52 provides an overview of the current and target performance for the assessed seven AP research
technological development and demonstration (RTD) initiatives within the three overarching technology
pathways of synthetic biology amp hybrid systems photoelectrocatalysis and co-electrolysis
93
Table 52 Overview of the current and target performance with respect to cost-efficiency lifetimedurability energy efficiency and resource use
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
Nitrogenase
activity wanes
within a few
days
Light energy
conversion
efficiency
gt10
(theoretical
limit ~15)
4 (PAR
utilization
efficiency) on
lab level (200 x
600 mm)
No data No data
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
CO2 reduction
energy
efficiency (full
system) gt10
(nat PS ~1)
NA (CO2
reduction
energy
efficiency for
full system) on
lab level
No data No data
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
gt500 hours
(stability goal)
gt40 hours
Solar-to-
hydrogen
(STH)
efficiency
gt17
STH efficiency
14
Reduction of
use of noble
metal Rh
catalyst and
use of Si-
based
substrate
material
1kg Rh for
1MW
electrochem
power output
Ge substrate
(for
concentrator
systems)
Si substrate
94
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Bandgap abs materials
Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency ~9
STH efficiency
49
Reduction of
use of rare Pt
catalyst
Pt used as
counter
electrode for
H2 production
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency
gt10
IPCE gt90
(efficiency
goal)
IPCE (incident
photon to
electron
conversion
efficiency) of
25
Reduction of
use of rare and
expensive raw
materials
High-cost Ru-
based photo-
sensitizers
used
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
SOFC capital
cost target
400 US$kW
Comp of
synthetic fuels
with fossil fuels
No data
gt20 years
(long term)
1000 hours
(stability goal)
~50 hours
(high SOEC
cell
performance
degradation
observed)
Power-to-
Liquid system
efficiencies
(full system
incl FT)
gt70
No data No data No data
Electrolysis cells for CO2
valorisation ndash Industry
research
Comp with
fossil chemi
and fuels (eg
CO ethylene
alcohols) 650-
1200 EURMt
No data
gt20 years
(long term)
10000 hours
(stability goal)
gt1000 hours
(laboratory
performance)
System
efficiencies
(full system)
gt60-70
95 of
electricity used
to produce CO
System
efficiencies
(full system)
40
No data No data
95
52 Current TRL and future prospects of investigated AP RTD initiatives
Table 53 presents an overview of the current TRL future prospects and an estimation of future required
investments for the assessed AP research technological development and demonstration (RTD) initiatives
It should be noted that due to the focus on specific selected AP RTD initiatives the investment requirements
listed below do not represent all of the RTD activities conducted by European research institutions
universities and industrial stakeholders within the three overarching technology pathways of synthetic biology
amp hybrid systems photoelectrocatalysis and co-electrolysis
Table 53 Overview of current TRL future prospects and estimated investment needs for investigated AP RTD initiatives
AP RTD Initiatives TRL achieved (June
2016)
Future Prospects Estimated Investment
needed
Photosynthetic microbial cell
factories based on cyanobacteria
TRL 3 (pres Init)
TRL 6-8 (for direct
photobiol ethanol prod
with cyanobacteria green
algae)
2020 TRL 4 (pres Init)
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Biocatalytic conversion of CO2 into
formic acid ndash Bio-hybrid systems TRL 3 2020 TRL 4
Direct water splitting with III-V
semiconductor ndash Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 (for III-VGe
tandem structures)
TRL 3 (for III-VSi tandem
structures)
2020 TRL 5 (for III-VGe
tandem structures)
2021 TRL 5 (for III-VSi
tandem structures)
Basic RTD 5-10 Mio euro
TRL 5 5-10 Mio euro
Direct water splitting with Bismuth
Vanadate (BiVO4) - Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 2020 TRL 5
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
TRL 3 2020 TRL 4
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
TRL 2-3 (for co-
electrolysis of H2O
(steam) and CO2)
2020 TRL 3-4 (for co-
electrolysis of H2O
(steam) and CO2)
Electrolysis cells for CO2
valorisation ndash Industry research
TRL 4 (for RE assisted
carbon compound
production)
TRL 3 (for full synthetic
photosynthesis systems)
2020 TRL 6 (for RE
assisted carbon
compound production)
2020 TRL 5 (for full
synthetic photosynthesis
systems)
TRL 6 10-20 Mio euro
53 Knowledge and technology gaps of investigated AP RTD initiatives
At present a number of significant scientific and technological challenges remain to be addressed before
successfully being able to scale-up existing laboratory prototypes of different AP technology approaches
towards the commercial scale
Table 54 presents an overview of the identified knowledge and technology gaps focusing on the assessed
AP research technological development and demonstration (RTD) initiatives
96
Table 54 Overview of knowledge and technology gaps of investigated AP RTD initiatives
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Photosynthetic microbial cell
factories based on
cyanobacteria
Further metabolic and genetic engineering of the strains
Further engineered cyanobacterial cells with respect to increased light
harvesting capacity
Streamlined metabolism toward hydrogen production for needed electrons
proteins and energy instead of being used in competing pathways
More efficient catalysts with higher turnover rates
Simple and reliable production systems allowing higher photosynthetic
efficiencies and the use of optimal production conditions
Efficient mechanisms and systems to separate produced hydrogen from other
gases
Cheaper components of the overall system
Investigation of the effect of pH level on growth rate and hydrogen evolution
Production of other carbon-containing energy carriers such as ethanol
butanol and isoprene
Improvements of the photobioreactor design
Up-scaling of photobioreactor (from present active surface of 200 x 600 mm)
Improvement of operating stability (from present about gt100 hours)
Improvement of PAR utilisation efficiency from the present 4 to gt10
Cost reduction towards a hydrogen production price of 4 US$ per kg
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Further metabolic and genetic engineering of strains
Reduction of reactive oxygen species (ROS) which are detrimental to cell
growth
Development of biocompatible catalyst systems that are not toxic to bacteria
Development of ROS-resistant variants of bacteria
Development of hybrid systems compatible with the intermittent nature of the
solar energy source
Development of strains for CO2 reduction at low CO2 concentrations
Metabolic engineering of strains to facilitate the production of a large variety of
chemicals polymers and fuels
Enhance (product) inhibitor tolerance of strains
Further optimisation of operating conditions (eg T pH NADH concentration
ES ratio) for high CO2 conversion and increased formic acid yields
Integration of enzymes into the hydrogen evolving part of ldquobionic leafrdquo devices
Mitigation of bio-toxicity at systems level
Improvements of ldquobionic leafrdquo device design
Up-scaling of ldquobionic leafrdquo devices
Improvement of operating stability (from present about gt100 hours)
Improvement of CO2 reduction energy efficiency towards gt10
Cost reduction of the production of formic acids and other chemicals
polymers and fuels
97
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Increased understanding of surface chemistry at electrolyte-absorber
interfaces
Further improvement of functionalization to achieve higher stabilities without
the need for protective layers
Reduction of defects acting as recombination centres or points of attack for
(photo)corrosion
Reduction of pinhole formation leading to reduced mechanical stability of the
Rh catalyst
Reduction of the amount of rare and expensive catalysts by the use of core-
shell catalyst nanoparticles with a core of an earth-abundant material
Reduction of material needed as substrate by employment of lift-off
techniques or nanostructures
Deposition of highly efficient III-V tandem absorber structures on (widely
available and cheaper) Si substrates
Development of III-V nanowire configurations promising advantages with
respect to materials use optoelectronic properties and enhanced reactive
surface area
Reduction of charge carrier losses at interfaces
Reduction of catalyst and substrate material costs
Reduction of costs for III-V tandem absorbers
Development of concentrator configurations for the III-V based
photoelectrochemical devices
Improvement of device stability from present gt40 hours towards the long-term
stability goal of gt500 hours
Improvement of the STH production efficiencies from the present 14 to
gt17
Cost reduction towards a hydrogen production price of 4 US$ per kg
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Improvements of the light absorption and carrier-separation efficiency
(currently still at lt60) in BiVO4
Better utilization of the solar spectrum by BiVO4 especially for wavelengths
close to the band edge (eg by plasmonic- andor resonance-enhanced
optical absorption)
Further development of novel water-oxidation catalysts based on for example
cobalt- and iron oxyhydroxide-based materials
Further development of the distributed n+ndashn homojunction concept for
improving carrier separation in high-donor density photoelectrode material
Improvement of the stability and avoidance of mass transport and light
scattering problems in devices based on nanoporous materials and DSSC
(Dye Sensitised Solar Cells)
Further development of Pulsed Laser Deposition (PLD) for (multi-layered)
WO3 and BiVO4 photoanodes
Although the near-neutral pH of the electrolyte solution ensures that the BiVO4
is photochemically stable proton transport is markedly slower than in strongly
alkaline or acidic electrolytes
Design of new device architectures that efficiently manage proton transport
and avoid local pH changes in near-neutral solutions
For an optimal device configuration the evolved gasses need to be
transported away efficiently without the risk of mixing
The platinum counter electrode needs to be replaced by an earth-abundant
alternative such as NiMo(Zn) CoMo or NiFeMo alloys
Improvement of device stability from present several hours towards the long-
term stability goal of 1000 hours
Scaling up systems to square meter range
Improvement of the STH production efficiencies from the present 49 to ~9
Cost reduction towards a hydrogen production price of 4 US$ per kg
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Deep molecular-level understanding of the underlying interfacial charge
transfer dynamics at the SCdye catalyst interface
Novel sensitizer assemblies with long-lived charge-separated states to
Design and construction of functional DS-PECs with dye-sensitised
photoanodes and dye-sensitised photocathodes (tandem DS-PEC structures)
Design and construction of DS-PECs where undesired external bias is not
98
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
enhance quantum efficiencies
Sensitizerndashcatalyst supramolecular assembly approach appears as effective
strategy to facilitate faster intramolecular electron transfer for long-lived
charge-separated states
Optimise the co-adsorption for efficient light-harvesting and charge collection
Organometal halide perovskite compounds as novel class of light harvesters
(for absorber applications in DS-PEC)
Encapsulation of perovskite compounds to prevent the dissolution in aqueous
solutions
Semiconductor quantum dots (QDs) as suitable sensitizers for DS-PEC
Exploration of more efficient OERHER catalysts with low overpotentials
Use of a redox mediator analogous to the tyrosine-histidine pair in PSII to
accelerate dye regeneration and thus achieve an increased charge
separation lifetime
One-dimensional TiO2 nanostructures such as TiO2 nanotubes and nanorods
to improved the charge transport properties and thus charge collection
efficiencies
Exploration of alternative SC oxides with more negative CB energy levels to
match the proton reduction potential
Search for alternative more transparent p-type SCs with slower charge
recombination and high hole mobilities
Further studies on phenomena of photocurrent decay commonly observed in
DS-PECs under illumination with time largely due to the desorption andor
decomposition of the sensitizers andor the catalysts
needed
Design and construction of DS-PECs with enhanced quantum efficiency
(towards 90 IPEC)
Ensure dynamic balance between the two photoelectrodes in order to properly
match the photocurrents
Development of efficient photocathode structures
Ensure long-term durability of molecular components used in DS-PEC devices
Reduce photocurrent decay due to the desorption andor decomposition of the
sensitizers andor the catalysts
Ensure active photosensitizer and catalyst for at least millions of cycles in 20ndash
30 years
Ensure long operating lifetimes (such as achieved for DSC) for stable DS-PEC
devices that incorporate molecular components Future work on developing
robust photosensitizers and catalysts firm immobilization of sensitizercatalyst
assembly onto the surface of SC oxide as well as the integration of the robust
individual components as a whole needs to be addressed
Scaling up systems to square meter range
Improvement of the STH production efficiencies IPCE (incident photon to
electron conversion efficiency) need to be improved from ~25 to gt90
Cost reduction towards a hydrogen production price of 4 US$ per kg
99
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Basic understanding of reaction mechanisms in co-electrolysis of H2O (steam)
and CO2
Basic understanding of dynamics of adsorptiondesorption of gases on
electrodes and gas transfer during co-electrolysis
Basic understanding of material compositions microstructure and operational
conditions
Basic understanding of the relation between SOEC composition and
degradation mechanisms
Development of new improved materials for the electrolyte (eg Sr- and Mg-
doped lanthanum gallate (LSGM) and scandium-stabilized zirconia (Sc- SZ))
Development of new improved materials for the electrodes (eg Sr- and Fe-
doped lanthanumcobaltate (LSCF)Sr-doped lanthanum ferrite (LSF)Co-
and Nb-doped barium ferrite (BCFN) and Sr- and Fe-barium cobaltate
(BSCF) perovskites)
Avoidance of agglomeration of Ni-particles and micro-cracks in Ni-YSZ
hydrogen electrodes
Avoidance of mechanical damages (eg delamination of oxygen electrode) at
electrolyte-electrode interfaces
Reduction of carbon (C) formation during co-electrolysis
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Replacing metallic based electrodes by pure oxides
Studies of long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O (steam) and CO2
Improvement of stability performance (from present ~50 hours towards the
long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Improvement of the co-electrolysis syngas production efficiencies towards
values facilitating the production of competitive synthetic fuels via FT-
processes
Cost reduction towards competitiveness of synthetic fuels with fossil fuels
Electrolysis cells for CO2
valorisation ndash Industry
research
Further research on catalyst development
Investigation of catalyst surface structure (highly reactive surfaces)
Catalyst development for a variety of carbon-based chemicals and fuels
Research on electrolyte composition and performance (dissolved salts current
density)
Research on light-collecting semiconductor grains enveloped by catalysts
Research on materials for CO2 concentration
Careful control of catalyst manufacturing process
Precise control of reaction processes
Development of modules for building facades
Stable operation of lab-scale modules
Stable operation of demonstration facility
Improvement of production efficiencies for carbon-based chemicals and fuels
Cost reduction towards competitiveness of the produced carbon-based
chemicals and fuels
100
54 Coordination of European research
Although RTD cooperation exists between universities research institutions and industry from different
European countries the majority of the activities are performed and funded on a national level Thus at
present the level of cooperation and collaboration on a pan-European level seems to be limited
There are few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7
projects and many research groups that are operating locally and are funded by national governments A low
degree of collaboration among different research groups was reported which results in a duplication of efforts
and a lack of generalized standards Synergies which could potentially boost research in artificial
photosynthesis are being overlooked Creating for example a communication platform to facilitate exchange
among actors could more easily promote the development of knowledge and increase the speed of discovery
and exploitation of new robust (effective and durable) photocatalysts innovative processes and devices etc
Another indicated weakness is the lack of collaboration between the already existing and ongoing projects
The coordination of research at a European level is mainly performed by AMPEA The European Energy
Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials amp Processes for Energy
Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging Technologies Artificial
photosynthesis became the first energy research subfield to be organised within AMPEA The goal of this joint
programme which was launched at the end of 2011 is to set up a thorough and systematic programme of
directed research which by 2020 will have advanced the technology to a point where commercially viable
artificial photosynthetic devices will be under development in partnership with industry
Currently AMPEA does not involve biological AP approaches as its main mission focuses on advanced
materials Therefore opportunities for research cooperation in the field of synthetic biology seem limited in the
short term
Furthermore it was stated that the current effectiveness of AMPEA to coordinate research at a European level
is limited also due to budget constraints and limited direct funding provided to AMPEA
Specifically efforts within AMPEA are currently centred on developing a concise RTD roadmap for AP
technologies in Europe The future implementation of this roadmap will require support on both national and
European levels
Table 55 (below) presents a list of European research collaborations within the investigated AP research
technological development and demonstration (RTD) initiatives
101
Table 55 (European) research cooperation within the investigated AP RTD initiatives
AP RTD Initiatives (European) Research cooperation
Photosynthetic microbial
cell factories based on
cyanobacteria
Initiative implemented by Uppsala University Sweden (within CAP) in cooperation with
Norwegian Institute of Bioeconomy Research (NIBIO)
Existing cooperation between Uppsala University and German car manufacturer VW
Biocatalytic conversion of
CO2 into formic acid ndash
Bio-hybrid systems
Initiative implemented by Wageningen UR Food amp Biobased Research and Wageningen UR
Plant Research International The Netherlands (within BioSolar Cells)
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
III-V semiconductor ndash
Silicon tandem absorber
structures
Initiative implemented by TU Ilmenau the Institute for Solar Fuels at the Helmholtz-Zentrum
Berlin and the Fraunhofer Institute for Solar Energy Systems ISE and the California Institute
of Technology (Caltech)
Existing cooperation between TU Ilmenau and epitaxy technology providers Space Solar
Power GmbH and Aixtron SE
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
Bismuth Vanadate
(BiVO4) - Silicon tandem
absorber structures
Initiative implemented by the Institute for Solar Fuels at the Helmholtz-Zentrum Berlin and
two Departments at Delft University of Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Further RTD was done at Repsol Technology Center from Spain in cooperation with
Catalonia Institute for Energy Research (IREC)
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
Initiative implemented by KTH Royal Institute of Technology Sweden in cooperation with
Dalian University of Technology China (within CAP)
Further RTD at University of Amsterdam (within BioSolar Cells) University of Grenoble
University of Cambridge and EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Existing cooperation between OMV and University of Cambridge
Existing cooperation between Siemens and EPFL
Co-electrolysis of steam
and carbon dioxide in
Solid Oxide Electrolysis
Cells (SOEC)
RTD performed at Technical University of Denmark Imperial College London University of
Sheffield and in previous years by Catalonia Institute for Energy Research (IREC) in
cooperation with Repsol Technology Center from Spain
Electrolysis cells for CO2
valorisation ndash Industry
Research
Initiative implemented by Siemens Corporate Technology (CT) in cooperation with the
University of Lausanne and the University of Bayreuth Germany
55 Industry involvement and industry gaps
Due to the low TRL (TRL 2-4) of present AP technology pathways in the areas of synthetic biology amp hybrid
systems photoelectrocatalysis of water (water splitting) and co-electrolysis the direct involvement of industry
in research and development activities in Europe is currently limited
Furthermore detailed information on industry activities in the AP field is difficult to find also due to issues of
confidentiality According to Cefic (European Chemical Industry Council) AP is regarded as a potentially
promising future technology option by the Councilrsquos members however information on industry involvement is
largely kept confidential
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research including
research in artificial photosynthesis However while companies are participating in local consortia such as
BioSolar Cells there currently seems to be a lack of cooperation between academia and industry at an
international level
102
Industry involvement in the area of synthetic biology amp hybrid systems
There is ongoing cooperation between Uppsala University and the German car manufacturer Volkswagen
within the framework of the European project ldquoPhotoFuelrdquo The project is coordinated by VW and focuses on
the production of butanol using micro-organisms
The European industry end users Volvo and VW are involved in the field of the design and engineering of
photosynthetic microbial cell factories based on cyanobacteria however are not directly involved in the
development of micro-organisms themselves
Furthermore in the USA the company Algenol Biofuels Inc is active in the field and operating a pilot scale
production unit
Industrial partners potentially interested in the development of ldquobionic leavesrdquo include the industry partners of
the Dutch BioSolar Cells programme Currently the coupling of the developed enzymes to the hydrogen-
evolving part of the device (ie the development of a full ldquobionic leafrdquo) is subject to ongoing patent procedures
by researchers of Wageningen UR
Industry involvement in the area of photoelectrocatalysis of water (water splitting)
The processes used for the deposition and processing of the devices based on two-junction tandem absorber
structures namely the metal-organic vapour phase epitaxy (MOCVD) and the in-situ functionalisation of
surfaces are generally scalable to an industrial level Spray pyrolysis processes used for the deposition of
dense thin films of BiVO4 are well-established industrial technologies and thus generally scalable to an
industrial level
Industrial stakeholders potentially interested in the area of direct water splitting with tandem absorber
structures include industry partners active in the field of epitaxy technology (eg producers and technology
providers such as Azur Space Solar Power GmbH and Aixtron SE which have ongoing long-term cooperation
with TU Ilmenau) suppliers of industrial process and specialty gases (eg Linde Group) and chemical
industries involved in catalytic processes (eg BASF Evonik)
Further interested industrial stakeholders include industry partners of the network Hydrogen Europe
(httphydrogeneuropeeu) and the Fuel Cells and Hydrogen Joint Undertaking (FCH JU
httpwwwfcheuropaeu) Hydrogen Europe (formerly known as NEW-IG) is the leading industry association
representing almost 100 companies both large and SMEs working to make hydrogen energy an everyday
reality The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) is a unique public-private partnership
supporting RTD activities in fuel cell and hydrogen energy technologies in Europe
The industry player Repsol from Spain was involved (on a research and development level) in the
development of photoelectrochemical water splitting based on metal oxides (WO3 BiVO4) through its Repsol
Technology Center in Spain in cooperation with the Department of Advanced Materials for Energy Catalonia
Institute for Energy Research (IREC) and the Department of Electronics University of Barcelona (UB) The
focus is currently centred on Pulsed Laser Deposition (PLD) for (multi-layered) WO3 and BiVO4 photoanodes
No full devices for photoelectrochemical water splitting have however yet been reported within this initiative
In the area of dye-sensitised PEC potentially interested industrial partners include the major fuel companies
Shell and Total who are already members of SOFI (Solar Fuels Institute based at Northwestern University)
an international research and innovation organisation with several European members (including the core
member Uppsala University) The Austrian fuel company OMV funds research at the Reisner Lab at the
Department of Chemistry at the University of Cambridge which is involved in both dye and catalyst
development
103
Successful technology transfer has recently been reported by Innovation Exchange Amsterdam (IXA) the
technology transfer office of the University of Amsterdam to the French company PorphyChem Rights were
licensed for the commercialisation of novel molecules for hydrogen generation so-called metalloporphyrins
innovative molecular photosensitizers which enable sustainable sunlight-driven hydrogen production from
water In cooperation with IXA the researchers filed patent applications with the European Patent Office on 26
February 2015 H-C Chen A M Brouwer Photosensitizer Europatent application 2015 EP15156740
The industry player Siemens AG from Germany is funding a project implemented by the Laboratory of
Photonics and Interfaces the Institute of Chemical Sciences and Engineering the School of Basic Sciences
and the Ecole Polytechnique Federale de Lausanne (EPFL) for the development of efficient photosynthesis of
carbon monoxide from CO2 using perovskite photovoltaics
Industry involvement in the area of co-electrolysis
Until today the involvement of industry in the research and development of the co-electrolysis of water and
carbon dioxide in Solid Oxide Electrolysis Cells (SOECs) in Europe is limited
Activities (on a research and development level) were performed by the industry player Repsol from Spain
through its Repsol Technology Center in cooperation with the Department of Advanced Materials for Energy at
the Catalonia Institute for Energy Research (IREC) The focus of these efforts is the replacement of metallic-
based electrodes by pure oxides offering advantages for industrial applications of solid oxide electrolysers
Thereby the aim is to ensure suitable H2CO ratios of the produced syngas (ie close to two) fulfilling the
basic requirements for synthetic fuel production
At present the focus of industrial engagement (eg sunfire Audi) for the production of synthetic carbon-based
fuels via concepts using (co)electrolysis and FT-processes favours water electrolysis (for the production of H2)
and the separate addition of CO2 in the FT-process over co-electrolysis of water and carbon dioxide
In April 2015 the company sunfire GmbH announced that it succeeded in producing synthetic diesel from air
water and green electrical energy A demonstration rig for power-to-liquids was inaugurated in November
2014 Recently the plant reached its full operating capacity and now produces synthetic diesel fuel Audi the
German car manufacturer and project partner of sunfire exposed the synthetic diesel to laboratory tests with
the result that the fuel was approved A larger plant needs to be developed in order to proceed towards a
commercial application of this process
An industry-driven approach towards the valorisation of carbon dioxide for the production of carbon-based
chemicals and fuels is implemented by Siemens Corporate Technology (CT) in Munich Germany This work is
implemented within the framework of the Siemens corporate project ldquoCO2toValuerdquo where catalyst
development is performed in cooperation with researchers from the University of Lausanne in Switzerland and
materials scientists at the University of Bayreuth
A small-scale lab unit based on an electrolyser cell is currently in operation at Siemens CT and a large-scale
demonstration facility is planned to be operational in the coming years in order to pave the way towards the
industrial application of this synthetic photosynthesis process for the production of carbon-based chemicals
and fuels to be introduced into the market
104
56 Technology transfer opportunities
The transfer of research to industrial application in artificial photosynthesis remains challenging In order to
attract the attention of the private sector artificial photosynthetic systems have to be cost-effective efficient
and durable The active involvement of industrial parties could help bring research prototypes to
commercialisation This step towards commercialisation requires sufficient critical mass and funding however
which cannot be borne by a single country
In the framework of the assessment of the seven AP technology approaches in the areas of synthetic biology
amp hybrid systems photoelectrocatalysis of water (water splitting) and co-electrolysis a number of ongoing
collaborations between research organisations and the industry as well as future opportunities for technology
transfer have been identified
Technology transfer opportunities in the area of synthetic biology
There are ongoing patent procedures by researchers at Wageningen UR on the coupling of developed
enzymes to the hydrogen-evolving part of the device (ie the development of a full ldquobionic leafrdquo)
Technology transfer opportunities in the area of photoelectrocatalysis of water (water splitting)
There are several patents filed by the researchers of TU Ilmenau and a patent on full device for direct
water splitting with III-V semiconductor based tandem absorber structures is under development
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC) and University of Barcelona (UB)
Successful technology transfer has been achieved by the technology transfer office of the University of
Amsterdam to the French company PorphyChem rights were licensed for the commercialisation of
metalloporphyrins as novel molecules for hydrogen generation which enable sustainable sunlight-driven
hydrogen production from water patent applications have been filed with the European Patent Office
There are technology transfer opportunities between OMV and the University of Cambridge and between
Siemens and EPFL on perovskite PV
Technology transfer opportunities in the area of co-electrolysis
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC)
There are technology transfer opportunities between Siemens and the University of Lausanne as well as
the University of Bayreuth
Table 56 below provides and overview of industry involvement and technology transfer opportunities
105
Table 56 Overview of industry involvement and technology transfer opportunities
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Uppsala University Sweden (within
CAP) in cooperation with Norwegian
Institute of Bioeconomy Research
(NIBIO)
Existing cooperation between Uppsala University
and German car manufacturer VW
Interest by end users Volvo and VW
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Wageningen UR Food amp Biobased
Research and Wageningen UR
Plant Research International The
Netherlands (within BioSolar Cells)
Industry partners of BioSolar Cells
Ongoing patent procedures by researchers of
Wageningen UR on the coupling of the developed
enzymes to the hydrogen evolving part of the
device (ie the development of a full ldquobionic leafrdquo)
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
TU Ilmenau Institute for Solar Fuels
at the Helmholtz-Zentrum Berlin and
the Fraunhofer Institute for Solar
Energy Systems ISE and the
California Institue of Technology
(Caltech)
Existing cooperation between TU Ilmenau and
epitaxy technology providers Space Solar Power
GmbH and Aixtron SE
Interest by suppliers of industrial gases (eg
Linde Group) and chemical industries involved
in catalytic processes (eg BASF Evonik)
Industry partners of network Hydrogen Europe
and the Fuel Cells and Hydrogen Joint
Undertaking (FCH JU)
Several patents filed by researchers of TU
Ilmenau
Patent on full device for direct water splitting with
III-V thin film based tandem absorber structures
under development
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Institute for Solar Fuels at the
Helmholtz-Zentrum Berlin two
Departments at Delft University of
Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
Further RTD at Repsol Technology
Center from Spain in cooperation
with Catalonia Institute for Energy
Research (IREC) and University of
Barcelona (UB)
RTD by Repsol Technology Center focus is
currently placed on Pulsed Laser Deposition
(PLD) for (multi-layered) WO3 and BiVO4
photoanodes No full devices for
photoelectrochemical water splitting have
however yet been reported
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC) and University of Barcelona (UB)
Dye-sensitised
photoelectrochemical cells -
molecular photocatalysis
KTH Royal Institute of Technology
Sweden in cooperation with Dalian
University of Technology China
Existing cooperation between OMV and
University of Cambridge
Existing cooperation between Siemens and
Successful technology transfer by technology
transfer office of University of Amsterdam to the
French company PorphyChem Rights were
106
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
(within CAP)
Further RTD at University of
Amsterdam (within BioSolar Cells)
University of Grenoble University of
Cambridge and EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
EPFL
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Fuel companies Shell and Total
licensed for the commercialisation of novel
molecules for hydrogen generation so-called
metalloporphyrins innovative molecular
photosensitizers which enable sustainable
sunlight-driven hydrogen production from water
Patent applications filed with the European Patent
Office
Technology transfer opportunities between OMV
and University of Cambridge and between
Siemens and EPFL on perovskite PV
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Technical University of Denmark
Imperial College London University
of Sheffield and Catalonia Institute
for Energy Research (IREC) in
cooperation with Repsol Technology
Center from Spain
RTD by Repsol Technology Center focus is the
replacement of metallic based electrodes by
pure oxides offering advantages for industrial
applications of solid oxide electrolysers
Sunfire and Audi (steam electrolysis and FT-
synthesis)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC)
Electrolysis cells for CO2
valorisation ndash Industry
research
Siemens Corporate Technology (CT)
in cooperation with the University of
Lausanne and the University of
Bayreuth Germany
Industry driven approach towards the
valorisation of carbon dioxide for the production
of carbon-based chemicals and fuels by
Siemens CT
Technology transfer opportunities between
Siemens and University of Lausanne University of
Bayreuth
107
57 Regulatory conditions and societal acceptance
The current very low oil prices as well as the low carbon price (ie the fee that must be paid for the right to
emit CO2 into the atmosphere) are hindering the market uptake of the low carbon AP-based production of
chemicals polymers and fuels (carbon-based fuels as well as hydrogen) In addition until today carbon
benefits are only monetised in the energy sector and not for the production of eg low carbon chemicals
Furthermore direct market incentives for solar fuels may be an opportunity for the future development of AP
technologies In addition investments made towards the establishment of a European infrastructure for
hydrogen storage and handling may be beneficial for the future development of AP technologies
Advancements in artificial photosynthesis have the potential to radically transform how societies convert and
use energy However their successful development hinges not only on technical breakthroughs but also on
the acceptance and adoption by energy users
It is therefore important to learn from experiences with other energy technologies (eg PV wind energy
nuclear energy biofuels) and thoroughly involve all societal actors in a discussion on the potential benefits
and drawbacks of the emerging technology already during the very early stages of development
Specifically barriers to social acceptance and issues causing public concern need to be addressed in an open
dialogue and potential measures mitigating concerns need to be discussed and implemented (where
possible) It needs to be kept in mind that the majority of the public is largely unaware of AP technologies
The following main topics are subject to public concern with respect to present AP technology pathways in the
areas of synthetic biology amp hybrid systems photoelectrocatalysis of water (water splitting) and co-
electrolysis
The use of genetic engineering and Genetically Modified Organisms (GMO) mainly for synthetic biology
approaches
The use of toxic materials for the production of AP devices which concerns all pathways
The use of rare and expensive raw materials for catalysts and absorber materials also for all pathways
Land use requirements for large-scale deployment of AP technology and land use competition with other
renewable energy options such as PV solar thermal applications and bioenergybiofuels
High societal costs involved in the development of AP technologies (efficiency and competitiveness of AP
technologies)
The importance of societal dialogue within the future development of AP technologies is widely acknowledged
within several national initiatives in Europe Initiatives on public involvement are implemented within the Dutch
BioSolar Cells programme and by the German National Academy of Science and Engineering (acatech)
109
6 Development roadmap
61 Context
611 General situation and conditions for the development of AP
Current energy technologies are unlikely to be sufficient to attain EU ndash and other international ndash long term
targets for the share of renewable energy sources in overall energy supplies beyond 2020 There is therefore
a strategic interest in supporting efforts to develop new energy technologies (and improve existing ones) and
to raise their competitiveness ndash eg in terms of costs efficiency and resource use ndash vis-agrave-vis those that are
currently available Thus from an energy policy perspective the motivation for accelerating the industrial
implementation of AP technologies arises from their potential to expand the available portfolio of competitive
sustainable energy sources thereby contributing to the continuation of the transition away from fossil fuels At
the same time from the perspective of growth and job creation developing and demonstrating the viability and
readiness for industrial deployment of AP technologies can be viewed as part of a wider industrial policy to
develop an internationally competitive European renewable energy technology industry
Processes based on AP have been identified as having the potential to deliver sustainable alternatives to
conventional fuels AP-based lsquowater-splittingrsquo processes may be used for the production of hydrogen or in
combination with lsquocarbon reductionrsquo for the production of carbon-based fuels (lsquosolar fuelsrsquo) and other higher
order carbon-based compounds However although AP technologies show great potential and despite the
significant progress in research in the AP field made in recent years there is still a significant way to go before
AP technologies are ready for industrial implementation
AP covers several technology pathways that are being developed in parallel and which are all at a low overall
level of technology readiness The individual processes sub-systems and components within the different
pathways are however at varying levels of maturity Consequently it is difficult to foresee the eventual
production efficiency costs and material requirements that could characterise future AP-based systems when
implemented on an industrial scale Moreover while it is possible that some AP technologies may end up
competing with each other complementarities and synergies may arise from AP technology development
activities that are currently being conducted largely in isolation from each other
To date application of AP has only been undertaken in small scale in laboratory conditions and the feasibility
of commercial industrial-scale deployment of AP systems has yet to be demonstrated Assuming that this can
be achieved at cost levels that enable AP-based products to be competitive in the marketplace commercial
implementation may raise some more practical issues for example in relation to land-use water availability
and other possible environmental or social concerns that have not as yet been fully explored
To appreciate the possible future role of AP technologies also requires consideration of other developments
shaping the energy supply and technology landscape Although by definition AP is concerned with the direct
conversion of solar energy into fuel technologies for specific processes developed within the context of AP
may eventually be linked to other renewable energy technologies for example if they are combined with
electricity generated from photovoltaics (PV) or other renewable sources such as wind energy Similarly the
production of lsquosolar fuelsrsquo using AP systems requires a source of carbon which may come in the form of CO2
from ambient air or alternatively by linking AP to carbon capture (and storage) systems90
90
See for example DG Research (2015) ldquoProceedings of the scoping workshop Transforming CO2 into value for a rejuvenated European economy Brussels 26th March 2015rdquo
110
Prospects for the future industrial implementation of AP technologies will not only depend on the lsquopushrsquo
provided by technological developments but will also depend on market lsquopullrsquo factors Not least the
commercial viability of fuels produced using AP technologies (and other renewable energy sources) will be
strongly influenced by price developments for other fuels particularly oil Current low oil and carbon
(emissions) prices must be taken into consideration as factors potentially hindering the market uptake of low
carbon AP-based production of chemicals polymers and fuels (including hydrogen) both now and in the
future
The overall market potential of solar fuels will also depend on public policy developments for example in
terms of regulatory frameworks and incentives affecting demand levels and costsprices of renewable energy
sources Similarly a concerted policy framework targeted towards promotion of a lsquohydrogen economyrsquo may
lead to a shift in emphasis for AP technology development towards hydrogen production (lsquowater splittingrsquo) ndash
already the more advanced area of AP research ndash and away from solar fuels Certainly until a higher
technology readiness level of AP is attained care should be taken to ensure that regulatory measures ndash
whether at European and national levels ndash do not impinge upon or hinder developments along the different AP
pathways
Finally in order to truly accelerate the industrial implementation of AP social acceptance and adoption of the
new technology by energy users must be acquired As it stands the majority of the public is largely unaware
of the development and significance of AP while those who are voice concerns about genetic engineering the
use of toxic materials the use of rare and expensive raw materials and the high societal costs involved in the
development along all technology pathways
612 Situation of the European AP research and technology base
Europersquos scientific communities form more than 60 of the 150 or so research groups on AP worldwide
boasting well-educated researchers and a diverse range of scientists - an interdisciplinary approach being
crucial for scientific advancement within this highly innovative field Together these groups cover all of the
identified existing technological pathways along which the advancement of AP might accelerate thus
increasing the likelihood of cooperation between European scientists with possible breakthroughs on any
given path
Significant improvements are still needed with respect to cost-efficiency lifetimedurability energy efficiency
and resource use for all existing AP technologies and progress is being made in addressing these knowledge
and technology gaps Yet while this technological development making strides along multiple pathways
simultaneously shows a considerable amount of potential the scientific community alone cannot accelerate
the development of the industrial implementation of AP Aiding the development from a currently low
technology readiness level and eventually commercialising AP will involve a host of enabling factors
including those of the financial structural regulatory and social nature
As it stands currently European investment into AP technologies falls short of the amounts being dedicated in
a number of non-European countries and it could be argued is rather short-term if not short-sighted Further
stifling the potential of these technologies is the fact ndash significant considering most European research activity
into AP operates at a national level (only one of the six consortia in Europe being pan-European) ndash that both
national research plans and their funding are fragmented lacking a necessary integrated approach Adding to
this fragmentation there appears to be a lack of cooperation between research groups and academia on the
one hand and between academia and industry on the other This suggests that there are some structural
barriers impeding the speed and success of the development and eventual commercialisation of AP in
Europe
111
Accelerating the development of AP requires bringing the best and brightest to the forefront of the research
being carried out in the field which would in turn involve a conscious effort to boost collaboration of the top
contributors across Europe - such an effort has been the cluster of several FP7 projects the good example of
which may well serve as a foundation on which to build in the future Once the divide between research
groups and academia has been breached and the technological advancement of AP technologies has been
given the push needed to be able to climb higher up the TRL scale interest from and in turn collaboration with
the industry should rise
62 Roadmap overview
The assessment of the existing lsquostate of the artrsquo undertaken for this study reveals that AP technologies are in
general currently at relatively low levels of technology readiness levels91
There are many outstanding gaps in
fundamental knowledge and technology that must be addressed before AP can attain the level of development
necessary for industrial scale implementation Moreover there is not as yet any compelling evidence to
suggest that any particular AP pathway or sub-approach therein can currently be identified as clearly lsquomore
promisingrsquo than another Given this situation it seems appropriate at least for the time being to adopt an
lsquoopenrsquo approach to possible support measures for AP-related research efforts which does not single out and
prioritise any specific AP pathway or sub-approach This conclusion corresponds to the broad consensus view
expressed by participants at the workshop on lsquoArtificial Photosynthesis in Horizon 2020rsquo held in May 2016
Notwithstanding the above assessment if AP is to establish a role in the overall portfolio of energy sources
then the longer-term objective must be to develop competitive and sustainable AP technologies that can be
implemented at an industrial scale Thus a technology development roadmap for AP must support the
transition from fundamental research and laboratory-based validation through to demonstration at a
commercial or near commercial scale and ultimately industrial replication within the market Upscaling of
technologies and integration of processes in a complete lsquovalue chainrsquo ie from light harvesting through to
solar fuel (and other AP-based products) will require greater levels of investment and inevitably will imply
making choices on which technology options to prioritise As the general aim (of the roadmap) is to accelerate
industrial implementation these choices should reflect market opportunities for commercial application of AP
technologies while bearing in mind the overarching policy objectives of increasing the share of renewable
energy sources in overall energy supplies
621 Knowledge and technology development
Following from the above in terms of knowledge and technology development activities the outline roadmap
for support for the development of AP technologies consists of three phases as illustrated in Figure 61 and
described in more detail in the following sub-sections
91
Although the situation of with respect to different process varies most are assessed to be only at TRL 3 or 4 (ie corresponding to lsquoexperimental proof of conceptrsquo or lsquotechnology validated in labrsquo)
112
Figure 61 General development roadmap visualisation
Phase 1 Phase 3Phase 2
Regional MS amp EU
Regional MS EU amp Private
Private amp EU
Private (companies)
FUNDINGSOURCE
TRL 9Industrial
Implementation
TRL 6-8Demonstrator
Projects
Pilot ProjectsTRL 3-6
TRL 1-3Fundamental
Research
RampDampI ACTIVITIES
2017 2025 2035
113
In the following description for convenience the timeline for activities is addressed in three distinct phases It
should be noted however that some AP technologies are more advanced than others and that they
accordingly could already be at or close to readiness for pilot projects (addressed under Phase 2)
Accordingly some laboratory-based validation (TRL 4) and lsquorelevant environmentrsquo validation projects (TRL 5)
may be envisaged within Phase 1 of the Roadmap Conversely as all fundamental knowledge and technology
issues will be not be solved within the 5-7 year time horizon foreseen for Phase 1 the need to support such
development through smaller scale research projects can be expected to continue into Phase 2 of the
Roadmap and possibly beyond
Furthermore in addition to support for fundamental knowledge and technology development the Roadmap
foresees the need to integrate lsquosupporting and accompanying activitiesrsquo (see Section 622) These activities
should run in parallel to the support for knowledge and technology development with initial activities starting
within Phase 1 of the Roadmap and continuing throughout the entire period of the Roadmap It may be
appropriate that some of the suggested activity areas are addressed as part of the proposed Networking
action (Action 2) and Coordinating action (Action 5)
Phase 1 - Time horizon short term (from now to year 5-7)
This phase will target the continuation of early stage research on AP technologies in parallel with initiation of
the process of scaling-up from laboratory based bench-scale projects towards pilot scale projects (ie to
validate whether bench scale projects are viable at a pilot scale) In keeping with the general status of AP
knowledge and technology development the scope of support during this phase should remain lsquoopenrsquo to all
existing (and potential) AP technology pathways and sub-options therein Such an approach should allow for
continued long-term advances in underpinning rsquogenericrsquo scientific knowledge that may lead to a breakthrough
in terms of newnovel approaches for AP while at the same time pushing forward towards addressing
technology challenges across the broad spectrum of AP pathwaysapproaches Notwithstanding this lsquoopenrsquo
approach eventual support may be directed towards specific topics that have been identified as areas where
additional effort is required to address existing knowledge and technology gaps
Under Phase 1 possible EU funding support should a priori be directed towards multiple small scale projects
(eg euro 3-5 million) that can complement existing regional and national programmes (and existing related EU-
level support)
Phase 1 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 1)
Recommendation Support for multiple small AP research projects
Objective To address outstanding gaps in fundamental knowledge and technology relating to AP
Rationale There are many remaining outstanding gaps in AP-relevant fundamental knowledge and
technology that must be addressed before AP systems can attain the level of development
necessary for industrial scale implementation This requires continued efforts dealing with
fundamental knowledge aspects of AP processes together with development of necessary
technology for the application of AP
Resources needed Project funding indicative cost circa euro 3-5 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact Strengthen diversify and accelerate knowledge and technology development for
processesdevices for AP-based production of hydrogen (water splitting) and carbon-based lsquosolar
fuelsrsquo
Priority
High
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
114
Recommendations to support knowledge and technology development (Action 2)
Recommendation Support for enhanced networking for AP research and technology development
Objective To improve information exchange cooperation and collaboration so as to increase efficiency and
accelerate AP-relevant knowledge and technology development towards industrial scale
implementation
Rationale AP research and technology development requires expertise across multiple and diverse
scientific areas both theoretical and applied Notwithstanding existing efforts to support and
enhance European AP research networks (eg AMPEA and precursors) AP research efforts in
the EU are fragmented being to a large extent organised and funded at national levels Further
development of EU-wide (and globally integrated) network(s) would promote coordination and
cooperation of research efforts within the AP field and in related fields addressing scientific
issues of common interest This action ndash offering secure funding for networking activities at a
pan-European level ndash should raise collaboration and increase synergies that potentially are being
currently overlooked
The broader international dimension of AP research and technology development could also be
addressed under this action In particular to develop instruments to facilitate research
partnerships beyond the EU (eg with US Japan Canada etc)
Resources needed Network funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact By providing a platform for knowledge exchange the speed of discovery and exploitation of
knowledge and technology developments should be accelerated both within the research
community and with industry
Priority
Medium
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
Recommendations to support knowledge and technology development (Action 3)
Recommendation AP Inducement Prize
Objective To provide additional stimulus for research technology development and innovation in the field
of AP while also raising awareness amongst the public and other stakeholders
Rationale The inducement prize would a priori target ldquoproof of conceptrdquo of AP at a bench-scale that meet
eligibility and award criteria set for the prize Experience suggests that lsquoinducement prizersquo
schemes can be particularly effective in situations corresponding to those of AP (ie where there
are a number of competing emergent technologies in the TRL 2-4 range that can potentially
deliver similar outcomes) The prize should provide an incentive for researchers to accelerate AP
RampD efforts and also potentially extend interest beyond the current AP research base to a wider
range of potential researchersinnovators
Resources needed Financial prize circa euro3 million
Prize organisation etc euro03 million
Actors involved Funding sources EU possible national (MS) contribution
Potential prize recipients Research and technology development institutions and (possibly)
industry
Expected impact Increased research intensity and wider participation resulting in turn to sooner than otherwise
demonstration of bench-scale AP devices This should provide for an earlier transition from
laboratory based research towards pilot projects
Priority
Medium
Suggested date of implementation92
Short (Phase 1)
92
Based on views gathered by the study there appears to be a general consensus that 3-4 years could be sufficient for the inducement prize contest timeframe Extending the timeframe for a longer period risks prize fatigue where contestants lose sight of the original prize aim and interest can start to wane
115
Phase 1 - Milestones
The scope of knowledge and technology development activities envisaged under Phase 1 is potentially very
broad as it covers multiple lsquopathwaysrsquo and a wide array of challengesissues ranging from general to highly
specific These concern each of the main AP steps (eg light harvesting charge separation water splitting
and fuel production) and range from materials issues device design and supporting activities such as process
modelling In general terms key criteria for evaluating overall progress towards the ultimate objective of
commercial implementation will revolve around factors such as efficiency of conversion of light into solar fuels
alongside the durability and potential cost-effectiveness of AP systems Shorter-term targets (lsquomilestonesrsquo)
could be set for minimum performance levels in terms of conversion efficiency (eg 10 conversion of solar
energy to hydrogen or to carbon-based fuels) although given the variation in progress across AP pathways
variable efficiency targets for individual pathways would seem appropriate
However if the purpose of the milestone is to mark the point of transition from Phase 1 to Phase 2 of the
Roadmap then a pragmatic milestone may be defined in terms of the development of an AP devicesystem
able to produce a lsquouseablersquo quantity of solar fuel in laboratory conditions sufficient to warrant further
development towards a pilot projectplant (Phase 2) In this regard it may make sense to a greater or lesser
degree to align the milestones for Phase 1 to the award criteria retained for the proposed inducement prize
Phase 2 - Time horizon medium term (from year 5-7 to year 10-12)
This phase will focus on reinforcing the implementation of pilot scale projects while initiating the process of
scaling up to a demonstration scale The scope of eventual support should focus on a limited number of
projects for the most promising AP technologies in order to demonstrate their viability at a pilot scale In this
context public (EU) funding support should be directed towards a limited number of medium scale projects At
the same time there should be encouragement of private sector participation in technology development
projects
Phase 2 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 4)
Recommendation Support for AP pilot projects
Objective To develop AP devices and integrated systems moving from laboratory scale up to an
(industrial) relevant scale of production This should enable comparative assessment of different
AP technology approaches at a production scale permitting industrial actors to make a
meaningful assessment of their potential viability for commercial deployment Equally these
projects should serve to identify (priority) areas where additional knowledge and technology
development is required in order to achieve industrial scale implementation
Rationale To reach industrial implementation of AP the feasibility of upscaling from laboratory conditions to
those approaching actual operational conditions needs to be demonstrated Accordingly pilot
projects under this Action item should provide for the testing and evaluation of AP devices to
assess and demonstrate the feasibility of reaching necessary characteristics (eg efficiency
levelstargets durabilitylife-cycle cost effectiveness) for commercial application for the
production of solar fuels The implementation of flexible pilot plants with open access to
researchers and companies should support (accelerated) development of manufacturing
capabilities for AP devices and scaling-up of AP production processes and product supply
Resources needed Project funding indicative cost circa euro 5-10 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Strengthen and accelerate knowledge and technology development for processesdevices for
AP-based production of hydrogen (water splitting) and carbon-based lsquosolar fuelsrsquo
Priority
High
Suggested date of implementation
Medium (Phase 2)
116
Recommendations to support knowledge and technology development (Action 5)
Recommendation Support for AP coordination
Objective To enhance efficiency (and effectiveness) of AP research efforts and more broadly to raise
coordination in the fields of solar fuels and energy technology development
Rationale There is a general need to ensure that research budgets are used effectively and to avoid
duplication of research effort In the context of AP there is a need to identify lsquomost promisingrsquo
technologies and set common priorities accordingly Moving to a common European AP
technology development strategy will require inter alia alignment of national research efforts in
the EU and (possible) cooperation at a broader international level Equally with the aim of
accelerating industrial implementation of AP there is a need to ensure cooperation and
coordination between research and technology development activities among the lsquoresearch
communityrsquo and industry
Resources needed Networkcoordination funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Improved coordination of AP research activities at European level (and possibly international
level) and improved priority setting to address knowledge and technology gaps for AP-based
processes and products
Priority
High
Suggested date of implementation
Medium (Phase 2) with possibility to extend implementation over
long term
Phase 2 - Milestones
The purpose of the AP pilot projects proposed under Phase 2 is inter alia to develop AP production
devicessystems operating at a sufficient scale to assess their potential viability for commercial deployment
Thus AP devicessystems developed within the pilot projects should attain sufficient performance levels and
fulfil basic operational and other characteristics (eg conversion efficiency lifetimedurability
sustainabilityresource use and cost-effectiveness) that are sufficient to attract the potential interest of private
sector (industry) investors Specific milestones for AP pilot projects may therefore be set in terms of multiple
target technical performance requirements but the overarching target lsquomilestonersquo for pilot projects will relate to
the overall assessment of their potential economic (commercial) viability conditional on further technological
developments (including engineering) and subject to their potential to comply with sustainability and other
social requirements
As a bottom line in terms of marking the point of transition from Phase 2 to Phase 3 of the Roadmap the test
for a lsquosuccessfulrsquo pilot project will be reflected in developing technology solutions able to attract private
investors willing to commit to their next stage of development either through a demonstration project (Phase
3) or directly to industrial implementation (lsquoearlyrsquo commercial projects)
Phase 3 - Time horizon long term (from year 10-12 to year 15-17)
This phase will focus of the development of ndash one or more ndash demonstration projects to assess the viability of
AP technologies at an industrial scale and facilitating the transfer of AP-based production systems from
demonstration stage into industrial production for lsquofirstrsquo markets The scope of eventual support should focus
on the AP technologies identified as most viable for commercialindustrial application However demonstration
level products should be led by the private sector ndash reflecting the need to assess commercial viability of
technologies ndash with co-funding provided by the public sector ndash reflecting the risk and large financial burden of
investments in such projects
117
Phase 3 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 6)
Recommendation Support for AP demonstrator projects
Objective To develop one or more demonstrator projects to assess the viability of AP technologies at a
close-to industrial scale (ie the project should be of a sufficient size to serve as a platform and
facilitating the transfer of AP-based production systems from demonstration stage into industrial
production for lsquofirstrsquo markets)
Rationale The demonstration project(s) provide a lsquostepping stonersquo between pilot projects and industrial
implementation The projects should not only provide validation of AP devices and systems but
also allow for developing and evaluating the integration of the full AP value chain93
By
demonstration the (commercial) viability of AP the project(s) should promote full industrial
investments that might otherwise be discouraged by the high cost and risk94
At the same time
beyond addressing technological and operational issues the demonstration projects should
address all other aspects ndash eg societalpolitical environmentalsustainability
economiccommercialfinancial legalregulatory geographic etc ndash necessary to evaluate how
AP based production of solar fuels could be implemented in practice
Resources needed To be determined
[Indicative budget envelope circa euro10-20 million per individual project However required funding
will depend on size and ambition of the project and may significantly exceed this amount]
Actors involved Funding sources Industry with EU support
Funding recipients Research and technology development institutions industry
Expected impact The projects should both build investor confidence in the commercial application of AP-based
solar fuel technologies and raise public confidence including in terms of safety and reliability
Priority
Medium
Suggested date of implementation
Long (Phase 3)
Phase 3 - Milestones
Given that the primary purpose of the demonstrator projects is to assess the viability of AP technologies at a
close-to industrial scale an initial milestone for such projects would be for the plants to be operational and to
be able to produce solar fuels in commercially significant volumes Ultimately the target lsquomilestonersquo will be to
produce solar fuels that are cost-competitive under actual market conditions and commercial requirements
while complying with other key requirements (eg safety societal acceptance etc)
622 Supporting and accompanying activities
The technological development of AP will throughout its various phases be guided by regulatory and market
measures as well as the degree of social acceptance In order to help secure favourable conditions for the
development and eventual commercialisation of AP technologies support will need to be provided from a very
early stage onwards within both of these spheres The prices of competing fuels and carbon emissions may
need to be regulated as well as incentives affecting the demand for renewable energy sources introduced
while the breadth of technological development regarding AP should not be hindered by regulation within the
current phase of research nor research into an eventual shift to a lsquohydrogen economyrsquo be put on the back
burner Thorough involvement of all societal actors in education and open debate regarding the potential
benefits and drawbacks of AP technologies as well as barriers to social acceptance and issues raising public
concern is also required At the same time the economic and commercial aspects of AP production
technologies and AP-produced solar fuels need to be understood including in terms of the development of
successful business models and the competitiveness of European industry in the field of AP and renewable
energy more generally
93
Where this covers the whole AP supplyvalue chain from upstream supply (eg materials components etc) to downstream demand (markets)
94 For example high cost resulting from accelerated investments to scale-up to industrial scale and high-risk profile resulting from uncertainty over which AP technologies may prove most successful together with uncertainty over operating costs and future market prices and demand for solar fuels etc These factors may otherwise discourage investments in (initial) full scale projects unless some public support is provided
118
There is potentially a wide range of themes ndash beyond purely technological and operational aspects ndash which
require to be better understood and which may be addressed through supporting and accompanying activities
including the following (non-exhaustive) topics
Industry engagement and technology transfer As far as can be ascertained the engagement of
industry in the field of AP technologies has to date been limited although because of its commercial
sensitivity it is difficult to obtain a clear picture of industrycompaniesrsquo interest in AP Nonetheless there is
a general view that a greater engagement of the industry would be beneficial for the development of AP
technologies and will become increasingly important as technologies reach higher TRLs and move closer
to commercial implementation An active involvement of industrial players in cooperative research projects
could facilitate the transfer of technology from the research community to industry (or vice versa) thereby
helping speed up the evolution from research prototypes and pilots to commercial implementation
Intellectual property protection To ensure future development and industrial application European
intellectual property in the area of AP should be adequately protected through patents At the same time
worldwide developments in AP-related patent-protected technologies should be taken into consideration
to ensure that Europe avoids potentially damaging dependences on non-European technologies
Regulatory conditions and support measures As a minimum AP technologies and products entering
the market should face a legal and regulatory environment that does not discriminate against their use and
provides a level playing field compared to other energyfuel types Beyond this there may be a public
policy justification (eg reflecting positive externalities of AP) for creating a specifically favourable
regulatory and legal framework to encourage the take-up and diffusion of AP technologies and products
At the same time other actions for example AP project financing support may be implemented to support
the industryrsquos AP investments these may be both for production investments but also for downstream
users faced by high switching costs (eg from fossil to solar fuels)
Societal aspects and safety AP technologies may potentially raise a number of public concerns that
need to be understood and addressed These may relate to safety aspects of the production storage
distribution and consumption of AP-based products for example there may be concern over the use of
genetically modified organisms (GMOs) in synthetichybrid AP processes Other areas of concern may
arise for example in relation to land use requirements or use of rare materials etc In general both
among the general public and even within the industry there is limited knowledge of AP Accordingly it
may be appropriatenecessary to implement activities to raise public and industry awareness of AP
Market potential relating to the assessment of the potential role and integration of AP energy supply and
demand Here multiple scenarios are possible for example depending on whether advances in AP
technology are targeted towards production of hydrocarbons or of hydrogen The former would require
fewer changes in terms of supporting infrastructure development (eg for fuel storage and distribution) but
is currently lagging behind in terms of AP technological development For the latter future market potential
will depend on the evolution towards a greater adoption of hydrogen-based fuel technologies Better
understanding of the shape and direction of market developments both within the EU and globally will be
important for assessing which AP technology developments offer the best prospects for future industrial
implementation At the same time the sensitivity of future prospects for AP technologies and products to
developments in the costs and market prices of competing (fossil and renewable) fuels should be
assessed
Industry organisation and business development relating to the assessment of future industrial
organisation of AP-technology production including the full supplyvalue chain for solar fuels (ie from
upstream supply of materials components equipment etc through fuel production to downstream market
supply including storage and distribution) Such an assessment will be required to better understand the
potential position and opportunities for the European industry in the area of AP which should also take
account of the business models and strategies for European players within the market
119
The aforementioned topics illustrate the diversity of the dimensions surrounding AP that require to be better
understood In a first instance more detailed economic legalregulatory social and other analyses of these
topics is warranted In turn this may lead to the formulation of more concrete policies and actions to develop
appropriate regulatory frameworks and to shape other market and business conditions in order to ensure a
supportive environment for the development and implementation of AP technologies and products
121
7 References
(1) Wilker M B Shinopoulos K E Brown K A Mulder D W King P W Dukovic G Journal of the
American Chemical Society 2014 136 4316
(2) Tachibana Y Vayssieres L Durrant J R Nature Photonics 2012 6 511
(3) Agency I E 2015
(4) Maeda K Domen K The Journal of Physical Chemistry Letters 2010 1 2655
(5) Ni M Leung M K Leung D Y International Journal of Hydrogen Energy 2008 33 2337
(6) Utschig L M Soltau S R Tiede D M Curr Opin Chem Biol 2015 25 1
(7) Chen L Chen F Xia C Energy amp Environmental Science 2014 7 4018
(8) Carmo M Fritz D L Mergel J Stolten D International Journal of Hydrogen Energy 2013 38 4901
(9) Fukuzumi S Curr Opin Chem Biol 2015 25 18
(10) Pinaud B A Benck J D Seitz L C Forman A J Chen Z Deutsch T G James B D Baum
K N Baum G N Ardo S Energy amp Environmental Science 2013 6 1983
(11) Ursua A Gandia L M Sanchis P Proceedings of the IEEE 2012 100 410
(12) Nelson D L Lehninger A L Cox M M Lehninger principles of biochemistry Macmillan 2008
(13) Alberts B Johnson A Lewis J Raff M Roberts K Walter P Classic textbook now in its 5th
Edition 2010
(14) Magnuson A Anderlund M Johansson O Lindblad P Lomoth R Polivka T Ott S Stensjouml K
Styring S Sundstroumlm V Hammarstroumlm L Accounts of Chemical Research 2009 42 1899
(15) Smolentsev G Sundstroumlm V Coordination Chemistry Reviews 2015 304 117
(16) Hammarstrom L Hammes-Schiffer S Accounts of chemical research 2009 42 1859
(17) Barber J Chemical Society Reviews 2009 38 185
(18) Gust D Moore T A Moore A L Faraday discussions 2012 155 9
(19) Centi G Perathoner S ChemSusChem 2010 3 195
(20) Hansen J Ruedy R Sato M Lo K Reviews of Geophysics 2010 48
(21) Pearson P N Palmer M R Nature 2000 406 695
(22) Faunce T A Lubitz W Rutherford A B MacFarlane D Moore G F Yang P Nocera D G
Moore T A Gregory D H Fukuzumi S Energy amp Environmental Science 2013 6 695
(23) Gorka M Schartner J van der Est A Rogner M Golbeck J H Biochemistry 2014 53 2295
(24) Gust D Moore T A Moore A L Accounts of chemical research 2009 42 1890
(25) Armaroli N Balzani V Angew Chem Int Ed Engl 2007 46 52
(26) House R L Iha N Y M Coppo R L Alibabaei L Sherman B D Kang P Brennaman M K
Hoertz P G Meyer T J Journal of Photochemistry and Photobiology C Photochemistry Reviews 2015 25 32
(27) Utschig L M Silver S C Mulfort K L Tiede D M Journal of the American Chemical Society 2011
133 16334
(28) Listorti A Durrant J Barber J Nature materials 2009 8 929
(29) Styring S Faraday discussions 2012 155 357
(30) Walter M G Warren E L McKone J R Boettcher S W Mi Q Santori E A Lewis N S
Chemical reviews 2010 110 6446
(31) Lewis N S Science 2016 351 aad1920
(32) Concepcion J J House R L Papanikolas J M Meyer T J Proceedings of the National Academy
of Sciences 2012 109 15560
(33) Barber J Tran P D Journal of The Royal Society Interface 2013 10 20120984
(34) Gersten S W Samuels G J Meyer T J Journal of the American Chemical Society 1982 104
4029
(35) Gust D Moore T A Moore A L Accounts of Chemical Research 2001 34 40
(36) Kalyanasundaram K Graetzel M Current opinion in Biotechnology 2010 21 298
(37) Wen F Li C Accounts of chemical research 2013 46 2355
(38) McCrory C C Jung S Ferrer I M Chatman S M Peters J C Jaramillo T F Journal of the
American Chemical Society 2015 137 4347
(39) Alenazey F Alyousef Y Almisned O Almutairi G Ghouse M Montinaro D Ghigliazza F
International Journal of Hydrogen Energy 2015 40 10274
(40) Asthana S Samanta C Bhaumik A Banerjee B Voolapalli R K Saha B Journal of Catalysis
2016 334 89
(41) Ihara M Nishihara H Yoon K S Lenz O Friedrich B Nakamoto H Kojima K Honma D
Kamachi T Okura I Photochemistry and photobiology 2006 82 676
122
(42) Ihara M Nakamoto H Kamachi T Okura I Maedal M Photochemistry and photobiology 2006 82
1677
(43) Fukuzumi S Yamada Y Suenobu T Ohkubo K Kotani H Energy amp Environmental Science 2011
4 2754
(44) Vignais P M Billoud B Meyer J FEMS microbiology reviews 2001 25 455
(45) Utschig L M Dimitrijevic N M Poluektov O G Chemerisov S D Mulfort K L Tiede D M The
Journal of Physical Chemistry Letters 2011 2 236
(46) Prince R C Kheshgi H S Critical reviews in microbiology 2005 31 19
(47) Brown K A Wilker M B Boehm M Dukovic G King P W Journal of the American Chemical
Society 2012 134 5627
(48) Lubner C E Applegate A M Knoumlrzer P Ganago A Bryant D A Happe T Golbeck J H
Proceedings of the National Academy of Sciences 2011 108 20988
(49) Iwuchukwu I J Vaughn M Myers N ONeill H Frymier P Bruce B D Nature nanotechnology
2010 5 73
(50) Yacoby I Pochekailov S Toporik H Ghirardi M L King P W Zhang S Proceedings of the
National Academy of Sciences 2011 108 9396
(51) Silver S C Niklas J Du P Poluektov O G Tiede D M Utschig L M Journal of the American
Chemical Society 2013 135 13246
(52) Grimme R A Lubner C E Bryant D A Golbeck J H Journal of the American Chemical Society
2008 130 6308
(53) Rumpel S Siebel J F Faregraves C Duan J Reijerse E Happe T Lubitz W Winkler M Energy amp
Environmental Science 2014 7 3296
(54) Volgusheva A Styring S Mamedov F Proceedings of the National Academy of Sciences 2013 110
7223
(55) Rozendal R A Jeremiasse A W Hamelers H V Buisman C J Environmental Science amp
Technology 2007 42 629
(56) Clauwaert P Toledo R Ha D v d Crab R Verstraete W Hu H Udert K Rabaey K Water
Science and Technology 2008 57 575
(57) Bajracharya S ter Heijne A Benetton X D Vanbroekhoven K Buisman C J Strik D P Pant
D Bioresource technology 2015 195 14
(58) Li M Canniffe D P Jackson P J Davison P A FitzGerald S Dickman M J Burgess J G
Hunter C N Huang W E The ISME journal 2012 6 875
(59) Zhang D Zhao Y He Y Wang Y Zhao Y Zheng Y Wei X Zhang L Li Y Jin T ACS
synthetic biology 2012 1 274
(60) Blankenship R E Tiede D M Barber J Brudvig G W Fleming G Ghirardi M Gunner M
Junge W Kramer D M Melis A science 2011 332 805
(61) Fujishima A Honda K Nature 1972 238 37
(62) James B D Baum G N Perez J Baum K N Square O V DOE report 2009
(63) Hanna M Nozik A Journal of Applied Physics 2006 100 074510
(64) Ross R T Hsiao T L Journal of Applied Physics 1977 48 4783
(65) Khaselev O Turner J A Science 1998 280 425
(66) Wang X Maeda K Chen X Takanabe K Domen K Hou Y Fu X Antonietti M Journal of the
American Chemical Society 2009 131 1680
(67) Kanan M W Nocera D G Science 2008 321 1072
(68) Brillet J Yum J-H Cornuz M Hisatomi T Solarska R Augustynski J Graetzel M Sivula K
Nature Photonics 2012 6 824
(69) Kim J H Kaneko H Minegishi T Kubota J Domen K Lee J S ChemSusChem 2016 9 61
(70) Gao L Cui Y Wang J Cavalli A Standing A Vu T T Verheijen M A Haverkort J E
Bakkers E P Notten P H Nano letters 2014 14 3715
(71) Standing A Assali S Gao L Verheijen M A van Dam D Cui Y Notten P H Haverkort J E
Bakkers E P Nature communications 2015 6
(72) Gao L Cui Y Vervuurt R H van Dam D van Veldhoven R P Hofmann J P Bol A A
Haverkort J E Notten P H Bakkers E P Advanced Functional Materials 2015
(73) Smolyakov G A Osinski M A Google Patents 2011
(74) Herrera A S Google Patents 2013
(75) Joo O S Jung K D Min B K Kim S H Oh J W Google Patents 2008
(76) Google Patents 2015
(77) Liu J Zhang Y Lu L Wu G Chen W Chemical Communications 2012 48 8826
(78) Li J Wu N Catalysis Science amp Technology 2015 5 1360
(79) Laguna-Bercero M A Journal of Power Sources 2012 203 4
123
(80) Graves C Ebbesen S D Mogensen M Solid State Ionics 2011 192 398
(81) Li W Wang H Shi Y Cai N International journal of hydrogen energy 2013 38 11104
(82) Fu Q Mabilat C Zahid M Brisse A Gautier L Energy amp Environmental Science 2010 3 1382
(83) Graves C Ebbesen S D Mogensen M Lackner K S Renewable and Sustainable Energy Reviews
2011 15 1
(84) Christopher K Dimitrios R Energy amp Environmental Science 2012 5 6640
(85) Sun X Chen M Jensen S H Ebbesen S D Graves C Mogensen M international journal of
hydrogen energy 2012 37 17101
(86) Ivy J Summary of electrolytic hydrogen production milestone completion report National Renewable
Energy Lab Golden CO (US) 2004
(87) Haering C Roosen A Schichl H Schnoumlller M Solid State Ionics 2005 176 261
(88) Mahmood A Bano S Yu J H Lee K-H Energy 2015 90 Part 1 344
(89) Jakobsson N B FRIIS P C BOslashGILD H J Google Patents 2014
(90) Stoots C M OBrien J E Herring J S Lessing P A Hawkes G L Hartvigsen J J Google
Patents 2011
(91) JABBAR M HOslashGH J Stamate E BONANOS N Google Patents 2013
[Ca
talo
gu
e n
um
be
r]
KI-N
A-2
7-9
87-E
N-N
KI-N
A-2
7-9
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LEGAL NOTICE
The information and views set out in this report are those of the author(s) and do not necessarily reflect the
official opinion of the Commission The Commission does not guarantee the accuracy of the data included in
this study Neither the Commission nor any person acting on the Commissionrsquos behalf may be held
responsible for the use which may be made of the information contained therein
More information on the European Union is available on the Internet (httpwwweuropaeu)
Luxembourg Publications Office of the European Union 2016
Catalogue number KI-NA-27-987-EN-N
ISBN 978-92-79-59752-7
ISSN 1831-9424
Doi 102777410231
copy European Union 2016
Reproduction is authorised provided the source is acknowledged
Printed in the Belgium
Europe Direct is a service to help you find answers
to your questions about the European Union
Freephone number ()
00 800 6 7 8 9 10 11
() The information given is free as are most calls (though some operators phone boxes or hotels
may charge you)
5
Abstract
Technologies based on Artificial Photosynthesis (AP) offer the potential to deliver sustainable ldquosolarrdquo
alternatives to fossil fuels which are storable and transportable and can thus respond to the problem of
intermittency of other solar wind and marine energy technologies AP research has intensified over the last
decade pursuing multiple approaches or ldquopathwaysrdquo that each have their own relative advantages and
challenges However as most AP technologies are still at a low level of technology readiness it is currently
not possible to identify those AP pathways and specific technologies offering the greatest promise for future
industrial implementation The study argues accordingly that possible public support should retain an
approach that for the time being keeps Europersquos AP options open The proposed roadmap for support for AP
technology development which could be supported under Horizon 2020 foresees actions to address current
gaps in scientific knowledge and technology capabilities while scaling-up the size of projects through the
implementation of pilot projects and demonstrator projects that can validate the viability of AP technologies at
a commercial scale Europe occupies a frontline position in AP research with 60 of the estimated 150
leading global research groups located in Europe However AP research in Europe is relatively less well-
funded than elsewhere notably in the US and Japan European research efforts are also fragmented driven
by national-level strategies and research programmes Therefore the proposed roadmap integrates actions to
support improved networking and cooperation within Europe and possibly at a wider international-level In
turn improved coordination of national research efforts could be achieved through the elaboration of a
common European AP technology strategy aimed at positioning European industry as a leader in the AP
technology field
7
Executive Summary
Objectives and methodology
Artificial photosynthesis (AP) is considered among the most promising new technologies able to deliver
sustainable alternatives to current fuel supplies often viewed as a potential ldquogame changerrdquo in the fields of
energy conversion and energy production AP can be used to produce hydrogen or carbon-based fuels ndash
collectively referred to as ldquosolar fuelsrdquo ndash that offer an efficient and transportable store of (solar) energy which
can be used as an alternative to fossil fuels and as a feedstock for a wide range of industrial processes
Set against the above background the purpose of this study is to provide a full assessment of the situation of
AP providing answers to the questions Who are the main European and global actors in the field What is
the ldquostate of the artrdquo and what are the main ldquobottlenecksrdquo in scientific and technological development What
are the key economic and technological parameters to accelerate industrial implementation Answers to the
questions provide in turn the basis for formulating recommendations on the pathways to follow and the action
to take to maximise the eventual market penetration and exploitation of AP technologies
To gather information on the direction capacities and challenges of ongoing AP development activities the
study has conducted a comprehensive review of scientific and other literature and implemented a survey of
academics and industrial players This information together with the findings from a series of in-depth
interviews provides the basis for a multi-criteria analysis to identify key bottlenecks for the main AP
technology pathways The study findings were validated at a participatory workshop of leading European AP
researchers which also identified scenarios and sketched out roadmaps for actions to support the future
development of AP technologies over the short to long term
Definition of Artificial Photosynthesis
For the purposes of this study artificial photosynthesis is understood to be a process that aims to mimic
the physical chemistry of natural photosynthesis by absorbing solar energy in the form of photons and
using this energy to generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
Main technology pathways for artificial photosynthesis
It is difficult to precisely define the parameters of AP but there are three main identifiable technology pathways
along which research and development is now advancing
Synthetic biology amp hybrid systems aim to mimic existing biological systems that perform different stages of
photosynthesis (ie light-harvesting charge separation or molecule synthesis) and combine them to produce
specific fuel molecules These technologies are at a very early stage (TRL 1-4) however researchers have
already produced small quantities of hydrogen through the water-splitting reaction and have demonstrated the
reduction of carbon dioxide to methane and acetate Research is also investigating the possibility of using
basic cells (biological) to host biological machinery to generate more complex fuel molecules The long-term
goal is to reliably generate large quantities of fuel molecules combining and converting simple starting
compounds such as H2 and CO2 into a series of different compounds using enzymes and synthetic organic
and inorganic catalysts
8
Photoelectrocatalysis combines and integrates photovoltaic (PV) technologies ndash ie semiconductor materials
able to generate electric current from sunlight ndash with water electrolysis in a photoelectrochemical cell (PEC) or
suspensions of photoactive nanoparticles thereby enabling solar energy to be used to produce hydrogen (and
oxygen) via a water-splitting reaction PV technologies are already deployed commercially and are producing
power on a megawatt scale (TRL 7-8) however PECs to perform photoelectrocatalysis are as yet at a
relatively low stage of development (TRL 2-4) The main challenges facing this technology involve developing
materials that have high solar-to-hydrogen (STH) efficiencies are cheap to manufacture (eg use earth-
abundant metals) and are stable for long periods of time
Co-electrolysis uses co-electrolysis of carbon dioxide and water to generate syngas (COH2) by
simultaneously reducing carbon dioxide and water using a high temperature solid oxide cell electrolyser
(SOEC) syngas can then be used to generate simple intermediate compounds that can be used as feedstock
for more complicated chemicals Water electrolysers ndash such as alkaline and polymer electrolyte membrane
(PEM) electrolysers ndash used to convert water into H2 and O2 are mature technologies (TRL 7-8) that have
been commercialised SOECs are at a lower level of development (TRL 3-5) and given their high electricity
requirements current research is focused on increasing their efficiency
Technology pathways for artificial photosynthesis and indicative selection of generated compounds
Source University of Sheffield (PV = Photovoltaics)
AP research in Europe
Research in the AP field ndash bringing together interdisciplinary expertise from biology biochemistry biophysics
and physical chemistry ndash has intensified over the last decade Today more than 150 research groups are
estimated to be active worldwide of which 60 are in Europe1 Interest from industry is growing as well
although it remains limited due to the overall low levels of readiness for commercial application of many AP
technologies
Europe has a diverse community of researchers active in the AP field and covering all the main pathways with
the largest numbers of research groups located in Germany the Netherlands Sweden and the UK The most
significant and only truly pan-European-level research network is AMPEA2 but most networks and consortia
are national Some Member States have set up their own AP research programmes roadmaps and funds and
1 Source study estimates
2 Advance Materials and Processes for Energy Application (AMPEA) which is one of the joint programmes of the Europe nargy Research
alliance (EERA)
9
there has been successful collaboration in several ongoing European-funded FP7 projects Overall however
the level of funding in Europe falls short of that available elsewhere and national research plans (and funding)
seem fragmented and scattered with a short-term focus and lacking an integrated approach with common
research goals and objectives Equally the level of collaboration between academia and industry seems to be
more limited in Europe compared for example to the US or Japan
Relatively few companies are active in the field of AP and they can be counted in the lsquotensrsquo rather than
lsquohundredsrsquo Co-electrolysis is the only area where AP-related technologies are currently commercially viable
while current industry research activities mostly concern photoelectrocatalysis where companies from various
sectors (eg ranging from automotive and electronics to chemicals and oil refining) are involved There is
some industry involvement in synthetic biology amp hybrid systems but it is limited reflecting the early stage of
research activities along this pathway
Main challenges to development and implementation of AP technologies
To form a sustainable and cost-effective part of future European and global energy systems and a source of
high-value and low carbon feedstock chemicals the development of AP technologies must address certain
fundamental requirements
Efficiency in each main step of AP light captureharvesting (eg maximising the percentage of the
spectrum that can be utilised) energy transfer to a reaction centre (eg minimising energy loss during the
transfer) and charge generation and separation to allow the desired chemical reaction to take place (eg
preventing charge recombination)
Durability of the system in terms of the amount of energy that can be produced during the lifetime of an AP
system which is a challenge because of the rapid degradation of some materials under AP system
conditions (eg lack of long-term stability in aqueous conditions or when exposed to sunlight)
Sustainability of material use eg minimising the use of rare and expensive raw materials
To meet these requirements the main AP technology pathways must overcome several gaps in fundamental
knowledge and technology development (see tables) Even if these gaps can be addressed and the feasibility
of commercial- and industrial-scale deployment of AP systems can be demonstrated at a cost level that
enables AP-based products to be competitive in the market place commercial implementation may raise other
practical concerns These may arise in relation to land use water availability and possible environmental or
social concerns which have not yet been fully explored
Synthetic biology amp hybrid systems
Knowledge gaps Technology gaps
Develop molecular and synthetic biology tools to enable
the engineering of efficient metabolic processes within
microorganisms
Improve metabolic and genetic engineering of
microorganism strains
Improve metabolic engineering of strains to facilitate the
production of a large variety of chemicals polymers and
fuels
Enhance (product) inhibitor tolerance of strains
Minimise losses due to chemical side reactions (ie
competing pathways)
Develop efficient mechanisms and systems to separate
collect and purify products
Improve stability of proteins and enzymes and reduce
degradation
Develop biocompatible catalyst systems not toxic to
micro-organisms
Optimise operating conditions and improve operation
stability (from present about gt100 hours)
Mitigate bio-toxicity and enhance inhibitor tolerance at
systems level
Improve product separation at systems level
Improve photobioreactor designs and up-scaling of
photobioreactors
Integrate enzymes into the hydrogen evolving part of
ldquobionic leafrdquo devices
Improve ldquobionic leafrdquo device designs
Up-scale ldquobionic leafrdquo devices
Improve light energy conversion efficiency (to gt10)
Reduce costs of the production of formic acids and other
chemicals polymers and fuels
10
Photoelectrocatalysis
Knowledge gaps Technology gaps
Increase absorber efficiencies
Increase understanding of surface chemistry at
electrolyte-absorber interfaces incl charge transfer
dynamics at SCdyecatalyst interfaces
Develop novel sensitizer assemblies with long-lived
charge-separated states to enhance quantum
efficiencies
Improve charge transfer from solid to liquid
Increase stability of catalysts in aqueous solutions
develop self-repair catalysts
Develop catalysts with low over-potentials
Reduce required rare and expensive catalysts by core-
shell catalyst nanoparticles with a core of an earth-
abundant material
Develop novel water-oxidation catalysts eg based on
cobalt- and iron oxyhydroxide-based materials
Develop efficient tandem absorber structures on (widely
available and cheaper) Si substrates
Develop nanostructure configurations promising
advantages with respect to materials use optoelectronic
properties and enhanced reactive surface area
Reduce charge carrier losses at interfaces
Reduce catalyst and substrate material costs
Reduce costs for tandem absorbers using silicon-based
structures
Develop concentrator configurations for III-V based
tandem absorber structures
Scale up deposition techniques and device design and
engineering
Improve device stability towards long-term stability goal
of gt1000 hours
Improve the STH production efficiencies (to gt10 for
low-cost material devices)
Reduce costs towards a hydrogen production price of 4
US$ per kg
Co-electrolysis
Knowledge gaps Technology gaps
Basic understanding of reaction mechanisms in co-
electrolysis of H2O (steam) and CO2
Basic understanding of the dynamics of
adsorptiondesorption of gases on electrodes and gas
transfer during co-electrolysis
Basic understanding of material compositions
microstructure and operational conditions
Develop new improved materials for electrolytes and
electrodes
Avoid mechanical damages (eg delamination of
oxygen electrode) at electrolyte-electrode interface
Reduce carbon (C) formation during co-electrolysis
Optimise operation temperature initial fuel composition
and operational voltage to adjust H2CO ratio of the
syngas
Replace metallic based electrodes by pure oxides
Improve long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O
(steam) and CO2
Improved stability performance (from present ~50 hours
towards the long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel
composition and operational voltage to adjust H2CO
ratio of the syngas
Improvement of co-electrolysis syngas production
efficiencies towards values facilitating the production of
competitive synthetic fuels via FT-processes
Cost reduction towards competitiveness of synthetic
fuels with fossil fuels
The AP technology development roadmap
Although AP technologies show great potential and despite significant progress made in recent years there is
still a significant way to go before they are ready for industrial implementation Although some aspects of AP-
based systems are well developed the assessment of the existing lsquostate of the artrsquo shows that AP
technologies are generally at low levels of technology readiness (eg TRL 3-4) Moreover there is not yet
compelling evidence to suggest any AP pathway (or sub-approach therein) is ldquomore promisingrdquo than another
This being the case it seems appropriate to adopt an ldquoopenrdquo approach to possible support measures for AP-
related research efforts in the near term which does not single out and prioritise any specific AP pathway or
approach
Nonetheless if AP technologies are to fulfil their potential it will be necessary to achieve the transition from
fundamental research- and laboratory-based validation to demonstration at commercial of near-commercial
scales this ambition forms the long-term goal for the proposed AP technology development roadmap
11
The roadmap distinguishes 3 phases (see figure below) and corresponding recommendations for specific
actions
Phase 1 (short term) Early stage research and scaling-up to pilot projects
Action 1 Support for multiple small AP research projects to address existing knowledge and technology gaps and to
promote long-term advances in scientific knowledge that may contribute to breakthroughs in novel
approaches for AP and to address technology challenges across the board of current (and potential) AP
pathways and approaches
Action 2 Support for enhanced networking of AP research and technology development to reduce fragmentation and
promote coordination and cooperation of research efforts in the AP and related fields through the support for
pan-European networking activities and promotion of research synergies
Action 3 Inducement prize to provide additional stimulus for research technology development and innovation
through a (financial) prize targeting ldquoproof of conceptrdquo of significant advances in the AP field
Phase 2 (medium term) Pilot project implementation and scaling-up to demonstrator projects
Action 4 Support for AP pilot projects to demonstrate the viability of AP concepts through support for a (limited)
number of pilot plant scale projects of the ldquomost promisingrdquo AP technologies
Action 5 Support for AP coordination to ensure effective use of research budgets and to avoid duplication of research
efforts Moving to a common European AP technology strategy requires inter alia alignment of national
research efforts and cooperation at a broader international level Equally to accelerate industrial
implementation cooperation and coordination of activities among the lsquoresearch communityrsquo and industry
should be promoted
Phase 3 (long term) Demonstrator project implementation
Action 6 Support for AP demonstrator projects to demonstrate the viability of AP technologies through support for one
or more demonstrator projects that facilitate the transfer of AP production systems to industrial production for
ldquofirstrdquo markets while allowing an evaluation of the development and integration of the full AP value chain (ie
from upstream supply of materials and components to downstream markets for AP-based products) The
demonstrator project(s) should also address other aspects (eg societal political environmental economic
and regulatory) necessary to evaluate the practical implementation of AP technologies
NB For convenience the timeline of these actions is presented in 3 distinct phases Some AP technologies are however
more advanced than others and could already be at or close to readiness for pilot projects Conversely certain fundamental
knowledge and technology issues cannot expect to be resolved in the short term Accordingly the different phases as
proposed within the roadmap should not be considered to define a strictly chronological sequencetiming of actions
12
Visualisation of the AP technology development roadmap with illustrative project examples
Source Ecorys
Phase 1 Phase 3Phase 2
TRL 9 Industrial Implementation
TRL 6-8 Demonstrator
TRL 3-6 Pilot Projects
TRL 1-3 Fundamental
2017 2025 2035
Example projects- Research on metabolic and genetic engineering of strains for photosynthetic microbial cell factories
- Research on strains for the production of a variety of chemicals polymers and fuels
- Research on the understanding of surface chemistry at electrolyte-absorber interface in PEC
- Development of novel water-oxidation catalysts for direct water splitting
- Research on improvements of light absorption and carrier separation efficiency in PEC devices
- Research on new materials for electrodes and electrolytes in electrolysis cells
-Research to improve the basic understanding of reaction mechanisms in co-electrolysis (dynamics of adsorptiondesorption of gases gas transfer degradation mechanisms etc)
Example of projects - Improvements of operating stability of microbial cell factories
- Improvements of bionic leaf device design
- Study on long-term durability of molecular components used in DS-PEC devices development of active photosensitizer and catalyst
- Improvement of device stability and STH production efficiencies for direct water-splitting devices at pilot plant scale
- Support the development of lab-scale modules and demonstration facilities of electrolysis cells for CO2 valorisation
- Support the upscaling of cells for efficient co-electrolysis of H2O (steam) and CO2 in Solid Oxide Electrolysis Cells (SOEC)
- Development at a near-commercial scale of demonstrator plant(s) for co-electrolysis
Example of projects- Pilot plant scale of photobioreactors for photosynthetic microbial cell factories
- Pilot plant scale of ldquobionic leafrdquo devices
- Development at a near-commercial scale of demonstrator plant(s) for direct water-splitting devices based on several absorber materials (eg dye-sensitised photo-electrochemical cell (DS-PEC) device silicon-based tandem absorber structures)
13
Supporting activities
Looking beyond the technological and operational aspects of the roadmap the study finds several areas
where actions may be taken to provide a better understanding of the AP field and to accelerate development
and industrial implementation namely
Networking and coordination of research With the exception of the few pan-European initiatives (eg AMPEA
and FP7 projects) the degree of collaboration among research groups is low Networking and coordination
activities (for example through Horizon 2020 Coordination amp Support Action - CSA) would contribute to reduce
duplication of efforts and facilitate exchange among researchers
Industry engagement and technology transfer Engagement of industry in development activities which has so
far been relatively limited will become increasingly important as AP technologies move to higher levels of
readiness for commercial implementation Encouraging active involvement of industrial players in research
projects could ease the transfer of technology from the research community to industry (or vice versa) thereby
helping expedite the evolution from prototypes and pilots to marketable products
Public policy and regulatory conditions To encourage industrial implementation and market penetration AP
technologies and products should face a legal and regulatory environment that offers a ldquolevel playing fieldrdquo
compared to other energyfuel types Beyond this reflecting the sustainability and environmental
characteristics of AP there may be a public policy justification for creating a regulatory and legal framework
and possibly other measures to specifically encourage the adoption and diffusion of AP technologies and
products
Safety concerns and societal acceptance AP technologies could potentially raise a number of public
concerns for example the safety aspects of the production storage distribution and consumption of AP-
based products the use of GMOs in synthetichybrid AP processes the use of rare expensive andor toxic
materials extensive land use requirements etc Such legitimate public concerns need to be identified
understood and properly addressed if AP is to overcome barriers to widespread societal acceptance These
aspects should be an integral part of an overall AP research agenda that provides for open dialogue even
from very early stages of technological development and identifies potential solutions and mitigating
measures
Protection of Intellectual Property To become a successful leading player in the development and industrial
application of AP technologies researchers and industry must be able to adequately protect their intellectual
(industrial) property rights (eg patent protection) without this becoming a barrier to overall technology
development and implementation It will be important to both protect European intellectual property rights
while also follow global developments in AP-related patent-protected technologies thereby ensuring that
Europe has a secure strategic position in the AP field and avoiding potentially damaging dependencies on
non-European technologies
15
Table of contents
Abstract 5
Executive Summary 7
Table of contents 15
1 Introduction 21
2 Scope of the study 23
21 Overview of natural photosynthesis 23
22 Current energy usage and definition of artificial photosynthesis 25
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the study29
231 Synthetic biology amp hybrid systems 31
232 Photoelectrocatalysis of water (water splitting) 31
233 Co-electrolysis 31
3 Assessment of the technological development current status and future perspective 33
31 Synthetic biology amp hybrid systems 34
311 Description of the process 34
312 Current status review of the state of the art 35
313 Future development main challenges 38
32 Photoelectrocatalysis of water (water splitting) 39
321 Description of the process 39
322 Current status review of the state of the art 41
323 Patents 44
324 Future development main challenges 45
33 Co-electrolysis 47
331 Description of the process 47
332 Current status review of the state of the art 52
333 Patents 53
334 Future development main challenges 54
34 Summary 54
4 Mapping research actors 57
41 Main academic actors in Europe 57
411 Main research networkscommunities 57
412 Main research groups (with link to network if any) 59
42 Main academic actors outside Europe 62
421 Main research networkscommunities 62
422 Main research groups (with link to network if any) 64
43 Level of investment 66
431 Research investments in Europe 67
432 Research investments outside Europe 71
44 Strengths and weaknesses 73
441 Strengths and weaknesses of AP research in general 73
442 Strengths and weaknesses of AP research in Europe 74
16
45 Main industrial actors active in AP field 76
451 Industrial context 76
452 Main industrial companies involved in AP 76
453 Companies active in synthetic biology amp hybrid systems 77
454 Companies active in photoelectrocatalysis 79
455 Companies active in co-electrolysis 82
456 Companies active in carbon capture and utilisation 83
457 Assessment of the capabilities of the industry to develop AP technologies 85
46 Summary of results and main observations 86
5 Factors limiting the development of AP technology 91
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges 91
52 Current TRL and future prospects of investigated AP RTD initiatives 95
53 Knowledge and technology gaps of investigated AP RTD initiatives 95
54 Coordination of European research 100
55 Industry involvement and industry gaps 101
56 Technology transfer opportunities 104
57 Regulatory conditions and societal acceptance 107
6 Development roadmap 109
61 Context 109
611 General situation and conditions for the development of AP 109
612 Situation of the European AP research and technology base 110
62 Roadmap overview 111
621 Knowledge and technology development 111
622 Supporting and accompanying activities 117
7 References 121
17
List of figures
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton
gradient NADPH and ATP 24
Figure 22 Worldwide consumption of fuel types by percentage 27
Figure 31 General development and supply chain 33 Figure 32 Diagrammatic representation of a PSI-platinum hybrid system 34
Figure 34 Photoelectrochemical cell capable of water oxidation using solar energy 40
Figure 35 PEC reactor types 42
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting
photoelectrochemical cells 47 Figure 37 Schematic diagram of water electrolysis being conducted in an alkaline electrolyser 48
Figure 38 Schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell 49
Figure 41 Research groups in Artificial Photosynthesis in Europe 62
Figure 42 Research groups active in the field of AP globally 66
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020 69
Figure 44 Hondarsquos sunlight-to-hydrogen station 80
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels 85
Figure 61 General development roadmap visualisation 112
19
List of tables
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
36
Table 01 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the
performance data for each device This table was originally constructed by Ursua et al 201211
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis
cell electrolysers This table was originally constructed by Carmo et al 20138 53
Table 41 Number of research groups and research institutions in European countries 59
Table 42 Number of research groups per research area (technology pathway) 60
Table 43 Number of research groups and research institutions in non-European countries 64
Table 44 Number of research groups per research area (technology pathway) 65
Table 45 Investments in the field of artificial photosynthesis 66
Table 46 EU FP6 and FP7 projects on artificial photosynthesis 68
Table 47 Total EU budget on artificial photosynthesis per technology pathway 68
Table 48 Summary of strengths and weaknesses of research globally 73
Table 49 Summary of strengths and weaknesses of research in Europe 75
Table 410 Overview of the size of the industrial community number of companies per pathway 77
Table 411 Organisations in synthetic biology amp hybrid systems 78
Table 412 Organisations in the field of photoelectrocatalysis 79
Table 413 Companies in co-electrolysis 82
Table 414 Organisations active in carbon capture and utilisation 83
Table 415 Summary of findings size of research community 87
Table 416 Summary of findings size of industrial community 89
21
1 Introduction
To establish a world-class technology and innovation sector that is fit to cope with the challenges up to 2020
and beyond the European Commission initiated an update of its EU energy research and innovation (RampI)
policy leading to the publication of the Communication ldquoTowards an Integrated Strategic Energy Technology
(SET) Plan Accelerating the European Energy System Transformation (C (2015) 6317 final) in September
2015 Under the heading ldquoKeeping Technology Actions Openrdquo the SET Plan Integrated Roadmap states that
ldquothe emergence of new technologies required for the overall transition of the energy sector towards
decarbonisation requires breakthroughs which have to be based on fundamental and generic knowledge at
the international state of artrdquo Artificial Photosynthesis counts among the most promising new technologies and
is often considered as a potential ldquogame changerrdquo technology in the fields of energy conversion and energy
production
The study ldquoAssessment of artificial photosynthesisrdquo has been implemented in the first semester of 2016
against this background the study aims to support future policy developments in the area in particular in the
design of public interventions allowing to fully benefit from the potential offered by the technologies The study
has three specific objectives The first objective is to provide a detailed review of the state of the art of artificial
photosynthesis technologies as well as an inventory of research players from the public and private sector
The second objective is to analyse the factors and parameters influencing the future development of these
technologies The third objective is to provide recommendations for public support measures aimed at
maximising this potential
The structure of the report is as follows Section 2 describes the scope of the study with a review of the
different types of Artificial Photosynthesis Section 3 provides an assessment of the technological
development based on a review of the literature Section 4 maps the main academic and industrial actors
Section 5 analyses the factors limiting the development of Artificial Photosynthesis technologies and a
development roadmap is presented in the Section 6
23
2 Scope of the study
21 Overview of natural photosynthesis
Photosynthetic and heterotrophic organisms exist together in a steady state in the biosphere Photosynthetic
organisms capture solar energy in the form of photons this captured energy is used to produce chemical
energy that the organism uses to form adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide
phosphate (NADPH) ATP and NADPH are then used to generate organic compounds such as carbohydrates
from water and carbon dioxide12
Photosynthesis can be broken down into two processes light-dependant
reactions and carbon-assimilation reactions where the latter are driven by the products of the light reactions
In the light reactions electrons are obtained from water molecules that have been oxidised in a process often
referred to as ldquowater splittingrdquo to form electrons (e-) hydrogen ions (H
+) and molecular oxygen (O2) The
electrons are driven through a series of membrane-bound carrier proteins including cytochromes iron-sulphur
proteins and quinones to produce a proton gradient which is used to generate ATP and NADPH this is
summarised in Figure 21 The carbon-assimilation reactions use NADPH ATP electrons and H+ to reduce
carbon dioxide in a series of enzymatic reactions to generate an array of compounds21213
The light-dependent and carbon assimilation reactions of photosynthesis take place in the chloroplasts of
eukaryotic cells Chloroplasts are intracellular organelles with a non-uniform shape similar to that of
mitochondria They both have inner and outer membranes that enclose an inner compartment which is
permeable to small molecules and ions respectively The thylakoid membrane contains the photosynthetic
pigments and enzyme complexes that carry out the light reactions and ATP synthesis and are on the inside of
the inner membrane Chlorophylls are present in the thylakoid membrane and are responsible for absorbing
solar energy in plants An array of chlorophylls is called a photosystem Chlorophylls are green pigments
consisting of long phytol chains with a polycyclic planar structure similar to the protoporphyr in haemoglobin
at the top of the molecule However instead of a Fe2+
at the centre there is a Mg2+
coordinated by four
nitrogen atoms The phytol chain is esterified to a carboxyl group in ring IV The groups on the edge of the ring
(=CH2 and -CH3) can be exchanged for other groups depending on the organism the chlorophyll is present in
The heterocyclic five-ring system that surrounds Mg2+
has an extended polyene structure with alternating
single and double bonds These compounds strongly absorb in the visible region and have high extinction
coefficients Plants always contain chlorophyll α and chlorophyll β which both absorb green light at slightly
different wavelengths this maximises the amount of light the organism can utilise Chlorophylls bind with
specific proteins and membranes to form light-harvesting complexes (LHCs) In addition to chlorophylls which
are the main pigments in plants there are accessory pigments called carotenoids that absorb photons that
have different wavelengths so more of the spectrum can be utilised When a photon is absorbed by a
chlorophyll an electron in the chromophore portion is raised to a higher energy state called the excited state
When the electron moves back down to its ground state it can release the energy as light or heat In
photosynthesis instead of the energy being released as light or heat it is transferred from the excited
chromophore to a neighbouring chromophore in a process called ldquoexcitation transferrdquo1213
All of the pigment molecules in a photosystem can absorb photons and transfer the energy to other pigments
but only a number of pigments are associated with the photochemical reaction centre (PRC) The excitation
energy can be passed through multiple pigment molecules until it reaches a pigment associated with the PRC
The PRC transduces the excitation energy into chemical energy by passing the excitation energy to a nearby
molecule acting as an electron acceptor This leaves the chlorophyll with a positive charge which is
neutralised by another electron donor the electron acceptor becomes negatively charged In this way
excitation caused by photon absorption causes electric charge separation and starts the oxidation-reduction
chain Light-driven electron transfer in chloroplasts during photosynthesis is carried out by a number of multi-
enzyme complexes in the thylakoid membrane1213
24
Photosynthetic bacteria usually have one or two reaction centres Purple bacteria pass electrons through a
pheophytin which is a chlorophyll without the Mg2+
at the centre of the ring to a quinone Green sulphur
bacteria pass electrons through a quinone to an iron-sulphur centre The photosynthetic machinery in purple
bacteria is made up of 3 basic units a single reaction centre (P870) a cytochrome bc1 electron-transfer
complex (similar to complex III found in mitochondria) and an APT synthase Absorption of a photon drives
electrons through pheophytin and a quinone to the cytochrome bc1 complex following which electrons pass
through this complex to the cytochrome bc1 complex and back to the reaction centre This movement of
electrons generates the energy needed by the cytochrome bc1 complex to pump protons across the
membrane and create the gradient that generates ATP1213
The photosynthetic apparatus of cyanobacteria and plants is more complex than that found in a one-system
bacterium due to them containing two photosystems in the thylakoid membrane Photosystem II acts like the
single photosystem found in purple bacteria It should be noted that the water-splitting reaction occurs at
PSII14
When the reaction centre of photosystem II (P680) is excited electrons are driven through the
cytochrome b6f complex which pumps hydrogen ions across the thylakoid membrane to generate a proton
gradient PSI aids in the reduction of NADP+ to NADPH by absorbing a photon at 700 nm to excite an
electron which is passed through a number of carrier molecules to plastoquinone and then to ferredoxin-
NAPD+ reductase which generates NADPH As previously discussed the proton gradient that has been
generated from transferring the electrons that were excited by the photons is used by ATP synthase to
generate ATP To summarise the light-dependent reactions cause water to split into oxygen electrons and
protons which are used to generate a proton gradient form NAPDH from NAPD+ and generate ATP The
main differences between the two photosystems are the wavelengths of light they absorb and that PSII
conducts water oxidation (while PSI does not) Both absorb photons and both are capable of generating
ATP12-16
In the carbon-assimilation reactions ATP and NADPH are used to reduce (gain electrons) carbon
dioxide to form phosphates starch and sugars as part of the Calvin cycle which takes place in the stroma
this process is also known as carbon fixation1213
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton gradient NADPH and ATP
Theoretically the efficiency of natural photosynthetic systems should be around 26 This is calculated by
knowing the energy content of a glucose molecule is 672 kcal mol-1
To generate a glucose molecule 48
photons with a wavelength of 680 nm are needed which together have an energy of 42 kcal per quantum
mole which is equal to 172 kcal mol-1
672 kcal mol-1
divided by 172 kcal mol-1
makes for 26 efficiency
However in reality an efficiency of less than 2 is usually achieved in optimal conditions17
The efficiency of
natural photosynthetic systems is limited by electron-hole recombination which is when the charge separation
25
process is not successful Even when this process is successful up to half of the energy from the excited state
of the chlorophyll is used2 Energy is also used by the organism to ensure other processes within the cell are
functioning The inefficiencies of natural photosynthesis highlight major areas where researchers are looking
to improve in artificial photosynthetic systems and are discussed over the next sections
Photodamage occurs in photosynthetic systems when solar energy cannot be effectively dissipated as heat or
be used to form photosynthetic products fast enough Upon photon absorption chlorophylls are excited to a
singlet state whereby under normal conditions the chlorophyll molecule will either pass the energy to another
chlorophyll molecule by FRET emit a photon or dissipate the energy as heat High levels of light increase the
amount of photosynthesis occurring as well as the amount of time chlorophylls spend in their singlet state
which increases the risk of chlorophylls forming longer-lived triplet states if the energy is not passed on or
dissipated fast enough Chlorophylls in their triplet state can photosensitise toxic chemicals such as singlet
oxygen which causes photodamage18
Natural photosynthetic systems limit photodamage with a process
called non-photochemical quenching using molecules called carotenoids that quench chlorophyll triplet states
by triplet-triplet energy transfer Carotenoids in their triplet state are low energy and quickly release their
energy through heat production and do not facilitate the production of singlet oxygen1213
This method of
photoprotection has been mimicked in artificial photosynthetic systems to extend their lifetimes and enable
them to work under intense light conditions
22 Current energy usage and definition of artificial photosynthesis
The current demand for energy is primarily met by the combustion of fossil fuel resources in the form of coal
crude oil and natural gas
26
Figure 22 shows that the energy demand has doubled over the last 40 years and it should be noted that this
demand is expected to double again by 205031719
The increased energy demand could be met by increasing
fossil fuel combustion However fossil fuel combustion is not a clean process and releases large amounts of
greenhouse gases such as carbon dioxide carbon monoxide and nitrogen oxides The accumulation of these
greenhouse gases in the atmosphere is increasing the average global temperature damaging the ozone layer
and causing more extreme weather2021
From these studies it is clear that using fossil fuels to meet the future
energy demand could cause irreversible damage to the environment and the human population2223
Due to
this much time money and resources are being dedicated to find clean stable and renewable energy
alternatives to fossil fuels2425
Current candidates include wind power tidal power geothermal power and
solar energy while the viability of nuclear power is currently under discussion due to the radioactive wastes
and potential emergency risks The majority of these technologies are currently expensive to operate
manufacture and maintain and produce rather small amounts of energy due to their low efficiencies This
report will focus on how solar energy is being utilised as a renewable energy source The sun provides
100x1015
watts of solar energy annually across the surface of the earth If this solar energy could be
harnessed with 100 efficiency the current energy demand for one year could be met within an hour In total
only 002 of the total solar energy received by earth over a year would be required161726
27
Figure 22 Worldwide consumption of fuel types by percentage Total fuel consumption was equal to 4667 Mtoe in 1973 and 9301
Mtoe in 2013 and is represented by the size difference of the two charts below The figure was adapted from The 2015 Key
World Energy Statistics report3 Mtoe = million tonnes oil equivalent This figure does not state whether the energy came
from a renewable source
Currently one of the best and most developed methods of utilising solar energy (photons) is by using
photovoltaic cells that absorb photons and generate an electrical current This electrical current can be
instantly used as a source of energy or it can be stored in a wide variety of batteries for later use There are a
number of disadvantages to solely relying on photovoltaics to provide us with all of our energy requirements
which are listed below
Photovoltaics can only be used in areas that have high year-round levels of sunlight
The electrical energy has to be used immediately (unless it is stored)
Batteries used to store electrical energy are currently unable to store large amounts of energy have short
lifetimes and their production generates large amounts of toxic waste materials
To address these disadvantages researchers are looking into ways that solar energy can be stored as
chemical energy instead of inside batteries as electricity This is the point where the research being conducted
begins to draw inspiration from photosynthetic organisms14
Photosynthetic organisms have been capable of
utilising solar energy to generate a multitude of complex molecules for billions of years27
Natural
photosynthetic systems are capable of producing two main fuel types hydrogen and carbon-based fuels
Hydrogen is generated from photon-driven in PSII and carbon-based fuels such as carbohydrates and lipids
are generated from the reduction of carbon dioxide with hydrogen (Calvin cycledark reactions)1628
Hydrogen
and carbon-based fuels are the main fuel types researchers aim to produce using artificial photosynthetic
systems29
Hydrogen is produced by splitting (oxidising) water with solar energy catalysts and water oxygen
is a by-product of water oxidation Hydrogen is the simplest fuel to produce and the majority of the
technologies discussed in this report have already had success producing it It is desirable however for
researchers to generate more complex carbon-based fuels such as carbon monoxide methane methanol and
higher order carbon-based compounds using solar energy carbon dioxide and water because carbon-based
fuels have a higher energy density than hydrogen and are used as our primary energy source It should be
noted that hydrogen does not exist in its molecular form in nature which means that it must be produced by
an energy input Hydrogen is most commonly produced by steam reforming natural gas or fossil fuels such as
propane diesel methanol or ethanol8 These methods produce low purity hydrogen and consume fossil fuels
so they do not relieve any fossil fuel dependencies and they further contribute to environmental concerns
In later sections of this literature review some of the main technologies that utilise artificial photosynthesis to
generate fuel molecules are discussed These technologies offer a potential method by which high purity
hydrogen can be produced by the water-splitting reaction using energy obtained from renewable sources
Hydrogen carbon monoxide and carbon dioxide are important feedstocks for making industrial products such
as fertilisers pharmaceuticals plastics and synthetic liquid fuels With more research it is hoped that it will
soon be possible to produce complex molecules from chemical feedstocks that have been produced using
28
renewable energy Technologies that directly convert solar energy to electrical energy (photovoltaics) have
been commercialised for a number of years and can generate electricity on a megawatt scale at large
facilities Success has also been gained with generating hydrogen with a number of technologies such as
biological hybrid systems photoelectrocatalysis and electrolysers (some sub-technologies in this pathway
have been commercialised and can produce power on a megawatt scale) which will also be discussed in this
literature review Some success has been had with generating these more complicated molecules by artificial
photosynthesis from chemical feedstocks but it should be noted that these technologies are still at an early
research and development stage Using recent literature a definition for artificial photosynthesis was
developed for this study and is provided below
Artificial photosynthesis is a process that aims to mimic the physical chemistry of natural
photosynthesis by absorbing solar energy in the form of photons and using the energy to
generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
This is a broad definition of artificial photosynthesis where the term physical chemistry includes any reaction
or process that takes place during natural photosynthesis The term fuel molecules encompasses the term
solar fuel and can include any molecule that the system has been designed to produce such as molecular
hydrogen hydrocarbons alcohols and carbohydrates Biomimetics refers to a system that aims to mimic a
biological system by including some aspects of a biological system such as photosystems I and II chlorophyll
molecules or the electron transport proteinsmolecules Nanotechnology can refer to systems that use organic
chemistry inorganic chemistry or surfaceinterface chemistry to generate artificial photosynthetic systems
Synthetic biology refers to biological systems that have been genetically engineered to either allow or prevent
a biological process to occur
To date much progress has been made in the development of artificial photosynthetic systems since the
conception of the term22628-35
The most common problems associated with artificial photosynthetic systems
arise from
Low efficiency
Inability to utilise the entire spectrum of photon wavelengths
Inability to efficiently separate the charged species
Most systems use expensive noble metals to conduct the chemistry36
Short device lifetimes
Should these synthetic fuels be produced at a large enough scale for commercial use a new set of problems
would appear associated with how the fuels should be stored and distributed Using artificial photosynthesis to
generate hydrocarbons that are already used as an energy source would require fewer infrastructural changes
than switching to a hydrogen economy Furthermore the production process needs to be easily scalable so
that fuels can be produced in a cost-effective way on a terawatt scale in a manner that can keep up with the
ever-increasing energy demand In the next section several different types of artificial photosynthesis
technologies are introduced that aim to effectively utilise solar energy
29
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the
study
Research and development related to the area of artificial photosynthesis encompass several technological
areas The different pathways for artificial photosynthesis are illustrated in
30
Figure 22 along with some of the compounds that can be generated from these technologies on their own or
by combining them It should be noted that while Figure 23 presents a broad selection of potential compounds
that can be produced the actual number of compounds that could potentially be generated by artificial
photosynthetic systems is limitless
Figure 23 Different routes by which artificial photosynthesis can take place and the products that can be generated by utilising the
different technologies This image was generated by The University of Sheffield PV = Photovoltaics
The efficiency and usefulness of artificial photosynthetic technologies are dependent on how well they can
perform three distinctive steps that are found in natural photosynthetic organisms namely
How efficiently they are able to capture incoming photons (percentage of the spectrum that can be
utilised)
How efficiently the system can transfer the energy to a reaction centre (minimising energy loss during the
transfer)
How well the system can generate and separate charges to allow the desired chemical reaction to take
place (preventing charge recombination)
The complexity of artificial photosynthetic systems occurs when multiple charges have to be separated for a
chemical reaction to occur The production of hydrogen and oxygen from the water-splitting reaction which is
probably the simplest reaction these systems must be capable of still involves the transfer of four electrons
and the generation of more complicated compounds will require even more charge-separation events to occur
The following sections discuss the artificial photosynthetic technologies as depicted in
31
Figure 22 which are synthetic biologyhybrid systems photoelectrochemical catalysis and co-electrolysis
231 Synthetic biology amp hybrid systems
This pathway aims to take existing biological systems that perform different stages of photosynthesis such as
the light-harvesting charge separation or molecule synthesis steps and combine them so they are able to
produce specific fuel molecules These biological molecules can be modified or combined with other biological
molecules or synthetic organicinorganic compounds so that they are able to produce specific fuel molecules
more efficiently It is known that natural photosynthetic systems contain a number of crucial components that
need to be included in synthetic biology and hybrid artificial photosynthetic systems For example they should
contain a light harvester (semiconductor or molecular dye) a reduction co-catalyst (hydrogenase mimic or
noble metal) and an oxidation co-catalyst (photosystem II mimic that is capable of producing molecular oxygen
and hydrogen) It should be noted that these technologies are at a very early stage of development
(laboratory level technology readiness level (TRL 1-4)) and are many years away from being commercialised
Briefly researchers are capable of producing small quantities of hydrogen through the water-splitting reaction
and have demonstrated the reduction of carbon dioxide to methane and acetate Researchers are also
investigating the possibility of using basic cells (biological) to host biological machinery that is capable of
generating more complex fuel molecules The long-term goal of these technologies will be to reliably generate
large quantities of specific fuel molecules from simple starting compounds such as hydrogen and carbon
dioxide which are combined and converted into a series of different compounds using a series of enzymes
and synthetic organic and inorganic catalysts
232 Photoelectrocatalysis of water (water splitting)
This pathway aims to develop efficient photovoltaics and photoelectrochemical catalysts that utilise earth-
abundant metals capable of generating oxygen and hydrogen through the water-splitting reaction38
Photovoltaics can be used to generate electrical energy directly from sunlight Photovoltaicssemiconductors
can be used in photoelectrochemical cells to produce hydrogen from the water-splitting reaction PVs and
PECs are among the most advanced areas of artificial photosynthesis Photovoltaics utilise semiconductor
materials that are capable of directly generating electrical currents (electrical energy) when exposed to certain
wavelengths of light These semiconductors have to be capable of utilising a range of photon wavelengths
efficiently and must have long lifetimes Photovoltaics have been commercialised and are producing power on
a megawatt scale Future developments in this field aim to increase device efficiency and lower the costs
associated with them (TRL 7-8) Photoelectrochemical cells are capable of producing electricity and fuel
molecules when exposed to certain wavelengths of light Fuel molecules such as hydrogen are produced by
electrolysing water (splitting water) which could provide an unlimited source of hydrogen that could be used to
generate power or reduce carbon dioxide Water-splitting cells require semiconductors that are able to support
rapid charge transfer at the semiconductoraqueous interface have long-term stability in aqueous
environments and are capable of utilising a range of photon wavelengths30
233 Co-electrolysis
This pathway provides an alternative method by which water oxidation can be performed Alkaline
electrolysers and polymer electrolyte membrane electrolysers have been mature technologies now for a
number of years and are capable of converting water and electricity to hydrogen and oxygen The co-
electrolysis pathway aims to use carbon dioxide-water co-electrolysis to generate syngas (COH2) which is
produced by simultaneously reducing carbon dioxide and water using high temperature solid oxide cell
electrolysers (SOECs)39
Syngas can be used to generate simple intermediate compounds that can be used
as feedstock for more complicated chemicals used in fertilisers pharmaceuticals plastics and synthetic liquid
fuels Methanol is an example of a simple molecule that can be made from syngas The dehydration of
methanol can be used to generate the cleaner fuel dimethyl ether which is being considered as a future
energy source40
As a technique to produce power co-electrolysis offers a number of advantages over other
techniques such as photovoltaics and wind power in that it is not site-specific and can continuously generate
32
power However these devices require large amounts of electricity to function which affects their operating
costs It is likely that these systems will have their electricity supplied to them by solar or wind power farms in
the near future
33
3 Assessment of the technological development current status and future perspective
This literature review will focus on three technologies (synthetic biologybiological hybrid systems
photovoltaicsphotoelectrochemical cells and co-electrolysis) that are currently using artificial photosynthesis
to generate energy in the form of electricity and fuels The majority of research into these technologies has
focused on improving device efficiencies lifetimes and producing hydrogen The review will conclude with
discussions about the fuels researchers are currently producing potential large-scale facilities to produce the
fuels and finally the potential directions research into artificial photosynthesis could pursue Figure 3 shows a
general development and supply chain for technologies that aim to use artificial photosynthesis to convert
solar energy into power and fuels It should be noted that each technology will have its own set of specific
challenges which will be discussed at the end of each respective section This literature review was
constructed using material from a number of sources such as peer-reviewed journals official reports and
patents that have been filed
Figure 31 General development and supply chain for technologies that aim to use a combination of photovoltaics and
photoelectrochemical cell artificial photosynthetic technologies to convert solar energy into power and fuels
34
31 Synthetic biology amp hybrid systems
311 Description of the process
Artificial photosynthetic systems that utilise synthetic biology aim to modify existing natural photosynthetic
systems at the genetic level or combine them with other biological systems and synthetic compounds to
produce a specific fuel or improve efficiency It should be noted that technologies based on using synthetic
biology and hybrid systems to produce solar fuels are still at the research and development stage (TRL 1-4)
however the use of these systems to produce a limited number of fine chemicals is more advanced with a TRL
3-7 The majority of technologies developed in this pathway have focused on producing hydrogen and only a
limited number of technologies are capable of producing more complex fuel molecules It should also be noted
that most of these systems are only capable of producing small amounts of fuel molecules for a short period of
time Natural photosynthetic systems can be broken down into three distinct processes that these systems
have to mimic light-harvesting energy transfer and charge generationseparation (catalytic reactions)1437
For
these technologies to be successful the systems have to be designed so that they consist of electron donors
and acceptors and attempt to mimic light-driven charge separation2 Generally these technologies aim to
combine biological molecules that have catalytic activity (enzymes such as PSI [NiFe]-hydrogenase and
[FeFe]-hydrogenase) or combine the enzymes with synthetic inorganic and organic compounds9 Examples of
when these systems have been successfully created are discussed below with figures and the TRLs of the
technologies are given after each technology has been discussed
Illustrations
Figure 32 A simplified diagrammatic representation of a PSI-platinum hybrid system that is used to generate H2 can be found below
showing PSI P700 chlorophyll a apoprotein A1 (red) and PSI P700 chlorophyll a apoprotein A2 (blue) The electron provided
by ascorbate is transferred to a cytochrome c6 where a photon excites the electron which is then passed through PSI where
it is transferred to the platinum (Pt) catalyst to generate molecular hydrogen This figure drew inspiration from Fukuzumi
2015 and Gorka et al 20149
35
Figure 33 A diagrammatic representation of a FeFe-hydrogenase I ndash cadmium sulphur (CdS) hybrid system that is used to generate
H2 The faded red structure represents the surface topography of FeFe-hydrogenase I the blue arrows represent the
movement of the electrons through the Fe-S clusters where hydrogen ions are converted to H2 and the yellow structures
represent the CaI capped CdS nanorods The figure was constructed using inspiration from Wilker et al 2014 using the
PBD file 3C8Y and edited using PyMol software12
312 Current status review of the state of the art
The first example of researchers successfully producing light-driven hydrogen from an artificial complex
composed of biological molecules and platinum was achieved by combining the PSI subunit PsaE from
Thermosynechococcus elongtus with an oxygen tolerant [NiFe]-hydrogenase from Ralstonia eutropha H16 to
form a PSI-hydrogenase complex This complex in presence of ascorbate (electron donor) was capable of
light-driven hydrogen production at a rate of 058 microM (mg chlorophyll)-1
h-1
41-43
(TRL 3)
Hydrogenases are enzymes that catalyse the reversible oxidation of molecular hydrogen while platinum is
also capable of reversibly photocatalytically oxidising hydrogen44
Researchers recently showed that when a
platinum nanocluster was attached to a PSI molecule the complex was able to produce hydrogen at a rate of
673 microM (mg chlorophyll)-1
h-1
- the general structure of this complex is highlighted in Figure 323
Systems
based on these original concepts have been optimised to achieve higher hydrogen production efficiencies of
up to 244 microM (mg chlorophyll)-1
h-1
It should also be noted that the electron donor (ascorbate) had to be
present in excess in both cases2345
It should also be noted that these hydrogen production rates are
comparable to those of natural photosynthetic systems which occur at a rate of ca 300 microM (mg chlorophyll)-1
h-1
46
(TRL 3-4)
Researchers recently proposed a model by which hydrogen can be generated using CaI capped CdS
nanorods The authors reported that light is absorbed by the CdS nanorods to excite two electrons which are
then transferred into the CaI cap where the two electrons are used to reduce two protons (H+) and generate
hydrogen (electrons are replaced in CdS by ascorbate) In a recent publication the authors showed that it is
possible to combine the CdSCaI nanorods with [FeFe]-hydrogenase in place of PSI (ascorbate is used as an
electron donor) In this biomimetic system the electrons are transferred to [FeFe]-hydrogenase where they
reduce H+ to hydrogen This system was shown to have a quantum efficiency of 20 be active for up to 4
hours and had a total turnover of 106 hydrogen before activity was lost The loss in activity was found to be
due to the inactivation of the CaI cap at the end of the CdS rod147
36
Figure 3 represents the system and process described above where the blue arrows represent the movement
of electrons from the CdSCaI nanorods to the iron-sulphur clusters in [FeFe]-hydrogenase (TRL 3-4)
Researchers were recently able to produce hydrogen using a PSI-cobaloxime complex when it was
illuminated with natural light Cobaloximes are vitamin B12 mimics capable of catalysing H+ reduction
Cobaloximes offer a number of advantages over hydrogenases in that they are not sensitive to oxygen their
synthesis is relatively simple and they are constructed from relatively cheap materials In this system sodium
ascorbate used a sacrificial electron donor and cytochrome c6 transported the electrons to the PSI-cobaloxime
complex Upon light absorption the electrons were excited and transported through PSI to the bound
molecular catalyst cobaloxime where hydrogen production occurs27
The maximum rate for the photoreduction
of water by this hybrid system was measured to be 170 mol hydrogen (mol PSI)-1
min-1
as was reached within
10 minutes of illumination It should be noted that after 90 minutes hydrogen production levelled off giving a
total turnover of 5200 mol hydrogen mol PSI-1
27
It is thought that the activity of the hybrid decreased due to
the dissociation of cobaloxime from PSI research efforts are currently underway to stabilise the hybrid
system27
This system is of particular merit because the PSI-cobaloxime hybrid is composed of earth-
abundant materials unlike the hybrid systems containing precious metals It should also be noted that there
are multiple molecular catalysts for hydrogen production other than the cobaloximes that can offer improved
stability solubility in water and better activity and have been discussed in a recent review6 (TRL 3-4)
The production of hydrogen at a rate of 2200 plusmn 460 micromol mg Chl-1
h-1
(a faster rate than natural photosynthetic
systems) has recently been demonstrated This was accomplished by generating a hybrid system consisting
of a PSI complex tethered to a [FeFe]-hydrogenase using a 18-octanedithiol nanowire and also crosslinking
cytochrome c6 to the PSI complex This four component system was then placed in a sodium phosphate buffer
containing the electron donor sodium ascorbate at pH 65 and illuminating the sample with natural light48
The
authors also reported results for complexes consisting of different nanowire lengths (3-10 carbons) and a
chain length of 8 carbons was found to give the highest hydrogen production rates this is most likely due to
the chain being long enough to minimise steric hindrance between the two proteins The hybrid system
retained its activity for up to four hours and it should be noted that the decrease in activity was attributed to
depletion of the electron donor (full activity was regained upon replenishing the ascorbate) It should also be
noted that the hybrid system regained its full hydrogen-evolving activity after being stored in anoxic conditions
at room temperature for 100 days48
(TRL 3)
The technologies above are only a few examples of the methods researchers have used to generate hydrogen
from hybrid systems Table 31 below summarises hydrogen production rates by a number of different hybrid
systems that all incorporate PSI into their complex The information in Table 31 was originally summarised by
Utschig et al 20156 All of the technologies in this table have a TRL of 3-4
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
PSI-catalyst system Rate of H2 production
[mol H2 (mol PSI)-1 s
-1]
TON (time hours)
PSI-nanoclusters photoprecipitated long liveda 49
0002 ndc (2000)
PSI-[NiFe]-hydrogenase genetic fusion 41
001 ndc (3)
PSI-nanoclusters photoprecipitated short-liveda 49
013 ndc (2)
PSI-[FeFe]-hydrogenase-PetF in vitro complexb 50
031 ndc (05)
PSI-Ni diphosphinea 51
073 (3)
PSI-[FeFe]-hydrogenase-Fd protein complexb 50
107 ndc (1)
PSI-molecular wire-Pt nanoparticlea 52
11 (12)
PSI-NiApoFd protein deliverya 51
125 (4)
PSI-cobaloximea 27
283 (15)
PSI-Pt nanoparticlea 45
583 (4)
PSI-molecular wire-[FeFe]-hydrogenasea 48
524 ndc (3)
a Redox mediator Cyt c6
b Redox mediator PC
c nd not determined
37
Researchers have generated a hybrid photocatalyst system capable of splitting water to produce hydrogen
and oxygen and capable of reducing carbon dioxide by rational design The system uses a semiconductor as
the light harvester and a biomimetic complex mimicking photosystem I as a molecular catalyst37
This work
highlights that the understanding of artificial photosynthetic systems is increasing as rational design can now
be used to construct biomimetic artificial photosynthetic systems (TRL 2)
Unicellular organisms such as Chlamydomonas reinhardtii are a type of green algae that can produce
hydrogen light-dependently using the enzyme [FeFe]-hydrogenase However hydrogen production rates in
photoactive organisms are limited by a number of physiological constraints This is due to electrons
generated by PSI being used in a number of reactions other than hydrogen production5354
Most photoactive
organisms will contain a form of photosynthetic electron transport ferredoxin (PETF) protein which provides
photosynthetic electrons generated by PSI for a number of metabolic pathways All of these pathways
compete for electrons with [FeFe]-hydrogenase Researchers recently genetically modified the affinity PETF
has for PETF-dependent ferredoxin-NADP+-oxidoreductase (FNR) without comprising the affinity PETF has
for [FeFe]-hydrogenase In this modified system PETF is still able to supply [FeFe]-hydrogenase with
electrons that it used to produce hydrogen but is less able to supply electrons to FNR which means that fewer
carbon dioxide fixation reactions occur Hydrogen production rates increased by nearly 5x in wild type cells
that had modified PETF53
(TRL 3)
Microbial biocathodes consist of an electrode that has electrochemically active microorganisms immobilised
onto its surface which are capable of reducing protons to hydrogen These systems offer a number of
advantages in that the cathode can be constructed from cheap materials and the microorganisms can self-
regenerate55
The first microbial biocathode consisted of three phases (1) acetate and hydrogen are oxidised
at a bioanode that has been inoculated with a mixed culture of electrochemically active microorganisms to
release carbon dioxide (2) only hydrogen is fed into the bioanode (3) the polarity of the cells is reversed
(direction of electron flow) and hydrogen production begins at the cathode55
Initially after the polarity is
reversed methane was produced at the biocathode and not hydrogen (TRL 4)
Bio-catalysed electrolysis is a microbial fuel cell-based technology that is capable of generating hydrogen and
other reduced products from electron donors (acetatewastewater) however these systems require an
external power source56
In this system acetate is oxidised at the anode by microorganisms in the presence of
high concentrations of ammonium and the electrons are transferred to a platinum catalyst (cathode) where
they reduce protons to hydrogen56
(TRL 3)
A recent paper has reported the reduction of carbon dioxide to acetate and methane using a water-splitting
reaction to produce hydrogen and sodium bicarbonate as the carbon source using microbial electrosynthesis
(MES)57
This system used an assembly of graphite felt and a stainless steel cathode This paper is important
because it presents the use of electrode materials derived from earth-abundant elements showcasing them
as particularly suitable for industrial scale-out due to their low cost (TRL 3)
Researchers at the University of Oxford developed a biological tool called ldquoSimCellrdquo A SimCell is a simple
non-replicating cell that has no well-defined function until a plasmid containing DNA coding a specific
function is inserted into the cellrsquos genome The inserted DNA could potentially provide all of the genetic
information needed by the cell to produce the proteins and enzymes required to produce specific fuel
molecules The SimCell has been optimised to be simple so that most of the energy the cell is using will go
towards carrying out the function of the newly inserted gene instead of maintaining numerous intracellular
processes5859
The SimCell could allow researchers to insert genetic information that codes the production of
target fuels thereby greatly increasing the number of potential fuel targets and the efficiency with which they
can be produced It is possible that this technology could be patented once it reaches a higher level of
maturity and a working system is demonstrated (TRL 1)
38
313 Future development main challenges
Synthetic biology amp hybrid artificial photosynthetic systems primarily focus on producing hydrogen however
research focused on the production of hydrocarbons using technologies such as MES is gaining momentum
Although these technologies are currently at the laboratory research and development stage (TRL 1-4) they
are improving quickly At a very small laboratory scale the systems are becoming efficient enough to produce
hydrogen at a rate that is comparable to that which occurs in natural photosynthesis although some
researchers have reported even faster production rates
Synthetic biology amp hybrid systems need to address a number of specific challenges before they can be
considered as commercially viable options for producing solar fuels Below some preconditions and
challenges regarding certain such systems are described
Protein Hybrid Systems
For proteins to be active their primary amino acid sequence must fold and adopt the correctly folded
structure Misfolded proteins can exhibit severely diminished activities
Proteins (and enzymes) are inherently unstable and sensitive to the pH temperature pressure and buffer
components and will often degrade over time which limits their use
Most hydrogenases are sensitive to oxygen so they must be kept under anaerobic conditions
Biological molecules can be produced at a large scale as shown by the biopharmaceutical industry
However the amount of biological molecules needed to produce the amount of fuel required to support
mankind would be huge and has not been calculated
One of the strongest properties of enzymes is that they exhibit a high level of specificity they are able to
produce specific molecules of high purity
Enzymes can be redesigned to give them new or improved functions within different environments60
However modifying protein and enzyme function is not trivial it is often a time-consuming process that
requires thorough understanding of the system although predictive tools for protein engineering are
improving
Enzymes are often very large molecules in which only a small percentage of the amino acid residues are
actively involved in catalysis Researchers could reduce the complexity of biological systems drastically if
they focused on stripping the enzyme down so it contains only the residues and cofactors needed for
catalytic activity on a simplified base framework of amino acids
Microorganisms
In a recent paper researchers investigated how hydrogen production can be enhanced and suppressed in
vitro They state that the main limitations of hydrogen production in microorganisms are the systemrsquos
sensitivity to oxygen and the competition between hydrogenases and NADPH-dependent carbon dioxide
fixation If these issues can be solved the technologies would be closer to commercialisation50
It should be
noted that microorganisms are capable of producing a number of fine chemicals on a commercial scale (these
are often produced in smaller amounts)
Microorganisms are highly complex in that a multitude of chemical reactions must take place so that the
organism can continue to function at the most basic level These extra reactions are major drawbacks if
these organisms are to be used to produce fuel molecules as most of the absorbed energy cannot be
used to produce the fuel molecules
To overcome this problem various aspects of the organismsrsquo genetic information can be modified to
minimise energy loss through side reactions
SimCells are simplified cells in that number of chemical reactions needed to sustain the organism are
minimised this means that more energy can dedicated to fuel production However these technologies
are currently in early stages of research and development and are not close to being produced on an
industrial scale
39
It is likely that fuel-producing microorganisms will have to be capable of expelling the fuel molecules
otherwise the fuel-producing cells will have to be destroyed to obtain the molecules
A major advantage of bacterial systems is that their genetic information can be modified so that they
produce a number of different fuel molecules However this is not a trivial task and the microorganisms
may not be able to survive when large concentrations of the fuel molecules are present
Bacterial cells can survive in a number of harsh conditions and they do not have to be in an ultra-clean
environment
Synthetic biology and hybrid systems face a unique challenge in that these systems are made by or are
genetically modified organisms (GMOs) GMOs are often subject to negative media attention and are often
portrayed and viewed to be unsafe by the public which means that the public may not want their fuel coming
from this source Some of the concerns surrounding the use of GMOs are valid and need to be investigated
One of the main concerns about the use of GMOs pertains to whether the GMO could have a severe effect on
the environment if it managed to migrate into the wild However this issue could be addressed by only using
GMOs that are not able to replicate (ie they are obtained from a secured parent cell) However most of the
concerns the public may have regarding GMOs could be solved by educating about GMOs and providing a
large body of scientific evidence that supports their safety
It should be noted that the authors could find no relevant patents for artificial photosynthetic technologies that
utilise synthetic biology amp hybrid systems
In conclusion synthetic biology amp hybrid systems that produce solar fuels are currently in the laboratory
research and development stage and it is too early to determine whether they would be a commercially viable
option However current research is promising and shows that they could be a valuable part of generating
solar fuels due to their high level of specificity and ability to be reengineered to carry out new and specialised
chemistry
32 Photoelectrocatalysis of water (water splitting)
321 Description of the process
This pathway aims to develop efficient photovoltaics and photoelectrocatalysts that utilise earth-abundant
metals capable of generating oxygen and hydrogen by splitting water38
The water-splitting (water oxidation)
reaction is one of the most advanced areas of artificial photosynthesis These systems that directly produce
fuel molecules from sunlight are currently in the early researchproof-of-concept stage (TRL 2-4) This means
that they are a number of years away from being a commercially viable method to produce synthetic fuels31
Water oxidation involves the removal of 4e- and 4H
+ to generate molecular oxygen (O2) and molecular
hydrogen (H2) In nature water oxidation is carried out by photosystem II in natural photosynthetic systems
The water-splitting reaction has the potential to provide a clean sustainable and abundant source of
hydrogen that could be used as energy or to reduce carbon dioxide to higher order hydrocarbons which is
why a considerable amount of time and money has been spent trying to improve the process
Photovoltaic cells (PVs) also known as solar cells utilise semiconductor materials that are capable of directly
generating electrical currents when exposed to certain wavelengths of light Light absorption by the
semiconductor promotes an electron from the low energy valence band to the higher energy conduction band
This creates an electron-hole pair that can be transported through the electrical device to provide power
Research focusing on PVs has focused on improving their efficiencies Initially efficiencies lt1 were
obtainable but the most recent generation of PVs can achieve efficiencies gt45 Research has shown that
the efficiencies of PVs can be greatly improved by using multi-junction instead of single-junction devices60
Efficiencies of different PV models have increased over the last 40 years this plot is courtesy of the National
Renewable Energy Laboratory Golden CO The most recent PVs have long lifespans (gt20 years) low
40
pollution levels and low operating costs30
However PVs do have some drawbacks in that they are expensive
to manufacture can only be used during the day in areas that receive a lot of sunlight utilise a fraction of the
available spectrum and it is problematic to store the energy in batteries3360
Problems associated with long-
term storage of energy could be overcome by storing the energy in chemical bonds of molecules such as
hydrogen alcohols and hydrocarbons which is why the research in the following section is of importance It
should also be noted that PVs have a TRL of 9 as they have been successfully commercialised and can
provide power on a megawatt scale
Photoelectrochemical cells (PECs) are capable of producing fuel molecules when exposed to certain
wavelengths of light or paired with a semiconductor (PV) Hydrogen can be produced by the water-splitting
reaction Figure 3 shows a schematic diagram of a PEC which is capable of conducting water oxidation in
two separate chambers Currently there are two primary methods by which solar fuels can be generated from
the water-splitting reaction in PECs The first is by direct photoelectrocatalysis at the semiconductor-
electrolyte interface (occurring at a solid-liquid junction) and the second is by coupling the electrochemical
(PEC) reaction directly to a buried p-n junction PV230
Both of these approaches require the generation of a
photovoltage sufficient to split water (gt 123 V)30
Photoelectrodes in PECs must have high surface stability
good electronic properties and suitable light absorption characteristics Water-splitting cells require
semiconductors that are able to support rapid charge transfer at the semiconductoraqueous interface have
long-term stability in aqueous environments and are capable of utilising a range of photon wavelengths30
These functions are obtained by using multi-junction configurations that use p- and n-type semiconductors
with different band gaps and surface-bound electrocatalysts The brief description of PVs has been included
because they are an essential component for a number of systems that photocatalytically split water
Illustration
Figure 34 The illustration below shows a photoelectrochemical cell capable of water oxidation using solar energy consisting of
separated titanium dioxide (TiO2) and platinum (Pt) electrodes Water oxidation occurs at the TiO2 electrode where oxygen
is formed during which process protons (H+) and electrons (e
-) are released H
+ pass through an ion transport membrane to
a compartment containing the Pt electrode where electrons are used to reduce H+ to hydrogen After this hydrogen can be
stored as an energy source or it can be used to reduce carbon dioxide to higher order hydrocarbon compounds
Explanations
According to the National Renewable Energy Laboratory the greatest gains in efficiency have been made with
the multi-junction PV cells The first single-junction GaAs cells developed in the mid-1970s and had
efficiencies of ca 22 (which is better than most of the more recent PV cells that have been developed) The
most recent multi-junction technologies have achieved efficiencies of up to 46 It should also be noted that a
41
greater number of p-n junctions a PV has the greater its efficiency This is because each p-n junction is made
from a different semiconductor material that can absorb light at a different wavelength increasing the amount
of the spectrum that can be utilised PVs based on crystalline silicone cells have shown a slow increase in
efficiency over the last 40 years starting from 14 and increasing up to 276 PVs utilising thin-film
technologies now achieve efficiencies up to 223 Thin-film technologies are a particularly promising branch
of PV due to them being lightweight and the potential to manufacture them by printing which would decrease
their production and installation costs
Figure 3 shows a schematic diagram of a PEC cell that was developed by Honda and Fujishima in 1972 and
was capable of the water-splitting reaction using a TiO2 electrode in tandem with a platinum electrode61
PEC
cells consist of three basic components a semiconductor a reference electrode and an electrolyte The
principles of PEC cell operation are simple a photon is absorbed by the semiconductor (TiO2) material which
causes electron excitation and the excited electrons move to the reference electrode (Pt) through a metal
wire The movement of electrons between the two materials generates a positive charge (holes) at the
semiconductor which combines with electrons in the oxygen molecules of water to form molecular oxygen
and hydrogen ions At the reference electrode the electrons can combine with hydrogen ions to form
molecular hydrogen In this study oxygen was generated at the TiO2 electrode and hydrogen was generated at
the platinum electrode
Since the initial study by Honda and Fujishima researchers have spent much time developing new materials
for anodic and cathodic processes that are capable of carrying out the same process with greater efficiency
and ability to produce more products3061
Currently the cost-effectiveness of using solar energy systems to
generate power and fuels is constricted by the low energy density of sunlight which means low cost materials
need to be developed so that enough sunlight can efficiently be captured Sunlight availability is intermittent
which means that the captured energy needs to be efficiently stored The efficiency of PEC water-splitting
devices is determined by measuring their solar-to-hydrogen (STH) efficiency this is defined as the amount of
chemical energy produced in the form of hydrogen divided by the solar energy input without the use of any
external bias10
322 Current status review of the state of the art
Currently there are two main approaches that are used to photocatalytically split water into oxygen and
hydrogen The first method utilises a single-visible-light photocatalyst (this is essentially a PV) with a narrow
band gap capable of absorbing photons in the visible spectrum has a suitable thermodynamic potential for
water splitting and is stable enough to avoid photocorrosion4 The drawbacks of this system include that it is
only capable of utilising a small region of the spectrum and the collection of oxygen and hydrogen is difficult
due to them being produced in the same region2 The second method uses a two-step mechanism which
utilises two photocatalysts (photoanode and photocathode) in tandem similar to the Z-scheme present in
natural photosynthetic systems2 This setup enables the system to utilise a larger range of visible light
because the free energy required to drive each photocatalyst can be tuned compared to the one-step system
(one photon is needed for each photocatalyst) In this system the oxygen and hydrogen generated via water
oxidation can be separated more efficiently from each other because they are produced at different sites
(oxygen is produced at the anode and hydrogen is produced at the cathode) this also reduces the likelihood
of charge recombination462
This second system is more desirable as the oxygen and hydrogen evolution
sites can be contained in separate compartments62
Theoretical calculations have highlighted that the
maximum efficiency of a single absorber PEC system could reach 29-31 whereas a tandem PEC system
could reach 40-41 further highlighting the advantages of using tandem devices106364
Efficiency calculations
for three different PEC configurations a single photoabsorber system a dual stacked photoabsorber system
and a dual side-by-side photoabsorber system were reported to be 112 228 and 155 respectively
These systems differ in the spatial distribution and number of photoabsorbers which will affect the range of
wavelengths that can be absorbed and therefore the materialsrsquo STH efficiency10
It should be noted that the
practical efficiencies of these devices will often be much lower due to the inefficiencies associated with the
catalysts and reaction overpotentials10
These calculations show that the best way to achieve higher
efficiencies in PEC devices is to use a dual stacked photoabsorber system
42
Recently four PEC reactor types were conceived to represent a range of systems that could be used to
generate hydrogen from solar energy Each system design can be seen in Figure 31062
Types 1 and 2 are
based on relatively simple photoactive nanoparticle suspensions whereas types 3 and 4 are based on more
complex planar arrays a brief discussion of each system is given below It should be noted that quoted STH
efficiencies are optimised values and do not take into account material lifetimes
Figure 35 The figure below shows four PEC reactor types including a (a) Type 1 reactor showing the plastic bags containing the
suspended hydrogen- and oxygen-evolving photoactive particles (b) Type 2 reactor showing the plastic bags containing
separated suspensions of photoactive particles capable of separately evolving hydrogen and oxygen (c) Type 3 reactor
showing a sun-orientated panel containing a layered PEC cell capable of producing hydrogen and oxygen and (d) Type 4
reactor the design of which consists of a similar layered PEC cell to Type 3 with an added parabolic receiver that is able to
concentrate light onto the PEC cell throughout the day These figures were originally constructed by Pinaud et al 201310
Type 1 This reactor has the simplest design It consists of a transparent plastic bag that contains a
suspension of photoactive particles in 01 M potassium hydroxide that are capable of simultaneously
evolving hydrogen and oxygen by the water-splitting reaction Photons at a variety of different wavelengths
are able to penetrate the plastic bag whereas the electrolyte evolved gases and photoactive particles are
held within the bag The authors modelled the photoactive particles as spherical cores coated with
photoanodic and photocathodic particles The authors calculated that this reactor type could achieve a
realistic STH efficiency of 10 however it should be noted that the hydrogen and oxygen evolved in this
system would need to be separated1062
43
Type 2 The design of this reactor is very similar to that of Type 1 in that it consists of photoactive
nanoparticles suspended in an electrolyte contained within clear plastic bags The main difference
between the two systems is that the hydrogen- and oxygen-evolving particles are contained within
separate bags which reduces the need for a gas separation step and increases the safety of the system
However the bag design has to be more complicated in that a redox mediator is required along with a
porous bridge between the hydrogen- and oxygen-evolving bags The STH efficiency of this system was
calculated to be 51062
Type 3 This reactor is composed of a layered planar electrode consisting of multiple photoactive layers
(multi-junction PVsemiconductor) that is submerged within an aqueous solution containing 01 M
potassium hydroxide encased within a clear plastic case Multiple photoactive materials are used so that
more of the solar spectrum can be utilised The anode (oxygen evolution) is at the top of the cell where it
absorbs photons of a certain wavelength and allows others to pass through to the cathode where they are
absorbed into another layer to drive hydrogen evolution Due to the fixed orientation of these cells they
have to have a large surface area to ensure they can absorb the maximum amount of photons1062
Type 4 This reactor is similar to Type 3 in that it consists of a flat PEC cell of a similar design (gas
evolution occurs in a similar manner) The main difference is that a solar tracking concentrator system is
used to focus sunlight onto the PEC cell This means that smaller and more efficient PEC devices can be
used to reduce costs The STH efficiency of this system was calculated to 12-181062
The costs of hydrogen production for a power plant consisting of each reactor type were assessed (it should
be noted that costs for Type 3 and 4 plants were considered to be more accurate due to availability of PV
pricing)10
Type 1 $160 H2kg
Type 2 $320 H2kg
Type 3 $1040 H2kg
Type 4 $400 H2kg
During early work with PEC cells researchers were able to achieve efficiencies of 124 for hydrogen
production over 20 hours using a p-GaInP2(Pt)rsquoTJGaAs electrode However it should be noted that current
density decreased from 120 mAcm2 to 105 mAcm
2 over the course of the experiment which was caused by
damage to the PEC cell65
Therefore although this device was able to achieve high efficiencies its lifetime
was too low
Water oxidation in the presence of a photocatalyst that has been combined with a co-catalyst has been
reported2 The role of the co-catalyst is to provide extra reaction sites and decrease the activation energy for
oxygen and hydrogen evolution Researchers must carefully choose the type of co-catalyst to use this is
because although some noble metal catalysts like platinum and rhodium are good for enhancing hydrogen
production they also catalyse the reverse reaction (convert oxygen and hydrogen back to water)66
To
circumvent this issue transition-metal oxides are often used as co-catalysts instead of noble metals as these
do not catalyse water reformation However these compounds are often more susceptible to degradation
when they are exposed to the reactive environments found in PECs4
The first example of a metal oxide being used to split water into oxygen and hydrogen was carried out by a
dinuclear ruthenium complex (the blue dimer)34
Electrochemical and in situ spectroscopic measurements
were used to measure hydrogen production when platinum and rhodium plates deposited with chromia
(Cr2O3) were used as the water-splitting material4 Coreshell-structured nanoparticles that have a noble metal
or noble metal oxide core and a Cr2O3 shell have been shown to be capable of acting as a co-catalyst for the
water-splitting reaction This presents a mechanism by which noble metals could be used as co-catalysts the
Cr2O3 shell has been shown to supress the water reformation reaction when coated onto palladium and
platinum cores4 Multiple transition metal oxides such as NiOx RuO2 and TiO2 can be used as co-catalysts
when they are treated with appropriate chemicals (TRL 3-4)
44
Researchers recently reported a catalyst that was formed upon the oxidative polarization of an inert indium tin
oxide electrode immersed in a solution containing 100 mM potassium phosphate and 05 mM cobalt (II) ions at
pH 70 Upon initiation of electrolysis at 129 V oxygen production was shown to increase linearly over 12
hours to reach a maximum of 100 microM h-1
(after 12 hours electrolysis was stopped)67
The catalytic activity of
the reaction was also shown to be pH-dependent which suggests that the hydrogen phosphate ion is the
proton acceptor (TRL 3)
In a recent publication a multi-junction design was used to absorb light and provide energy for the water-
splitting reaction Multi-junction PVs are more efficient as they are able to absorb enough solar energy to
provide the free energy for water splitting The researchers developed a device based on an oxide
photoanode (Fe2O3 or WO3) and a dye-sensitized solar cell which performs unassisted water splitting with an
efficiency of up to 31 STH Incoming light was absorbed by the photoanode where the water-splitting
reaction and oxygen evolution takes place Electrons were transported to a platinum cathode where hydrogen
formation occurred68
(TRL 4)
Recently researchers demonstrated water splitting using tandem PEC cells where PtCdSCGSACGSe was
used as the photocathode (hydrogen evolution) and NiOOHFeOOHMoBiVO4 as the photoanode (oxygen
evolution) The cell was able to sustain a stable water-splitting reaction for 2 hours with an STH efficiency of
06769
(TRL 3)
Photochemical hydrogen production by nanowire arrays has been shown to be advantageous to more
traditional system designs because they use less precious material to produce7071
Researchers recently
showed that photoelectrochemical hydrogen production from water was possible using InP nanowire arrays In
these systems the chosen nanowire compound has a layer of silicone oxide (SiO2) deposited onto its surface
and then a co-catalyst deposited onto the surface of Efficiencies of 52 and 64 were obtained when the
InP nanowires were deposited with platinum and MoS3 respectively7072
Silicon is an abundant low-cost
semiconductor commonly used in PV devices and photoelectrochemical hydrogen generation at the
Sielectrolyte interface has been extensively studied for decades Hydrogen is evolved slowly at the
Sielectrolyte interface which has led to research efforts to modify the surfaces with electrocatalysts such as
platinum and ruthenium which are showing good activities and efficiencies71
(TRL 2-3)
323 Patents
Patents have been filed for systems based on nanoparticle suspensions and PECs some of which are
discussed below
A patent was filed in 2012 detailing a suspension of photoactive nanoparticles consisting of metallic cores and
semiconductor photocatalytic shells that can photocatalytically split water to directly obtain hydrogen The
efficient and unassisted photocatalytic splitting of water by the nanoparticles is based on resonant absorption
from surface plasmon in the metal coresemiconductor shell hybrid nanoparticles which can extend the
absorption spectra towards the visible-near infrared range This increases the solar energy conversion
efficiency When the photoactive nanoparticles are used in combination with scintillator nanoparticles the
hybrid photocatalytic nanoparticles can be used to convert nuclear energy into hydrogen73
(TRL 3-4)
A patent was recently filed for a PEC cell consisting of melanin melanin precursors melanin derivatives
melanin variants melanin analogues natural or synthetic pure or mixed with organic or inorganic compounds
metals ions drugs that act as the water electrolyzing material This technology uses solar energy as the sole
or main source of energy to produce hydrogen from water The system integrates a semiconductor material
and a water electrolyser inside a monolithic design that produces hydrogen directly from water using light
between 200 to 900 nm as the main or sole source of energy The technology aims to meet two criteria (i) the
system or light-absorbing compound should generate enough energy for the water-splitting reaction to be
45
completed and (ii) the materials need to be cheap to source and exhibit high stability in water and the reactive
environment The authors claim that all of these requirements can be met by melanin and related compounds
which represents a significant advancement in PEC design The technology can be used to generate
hydrogen oxygen and high energy electrons It can also be used to perform the opposite reaction and
generate water from electrons protons and oxygen and can be coupled to other processes generating a
multiplication effect It can also be used for the reduction of carbon dioxide nitrates and sulphates or others74
(TRL 2-3)
In 2008 a patent was filed describing a PEC system that could produce hydrogen from water The device was
comprised of (i) an electrolytic bath containing an electrode for catalytic oxidation an electrode for catalytic
reduction and an ion separation film disposed between the two electrodes immersed in an aqueous
electrolyte solution and (ii) a photoelectrode positioned outside the electrolytic bath and electrically connected
to the two electrodes This PEC system is characterised by disposing a photoelectrode at a position which
does not contact the electrolyte solution preventing the lowering of the photoelectrode activities and which
maximises hydrogen production efficiency75
(TRL 3)
In 2014 a patent was filed describing an invention that was able to generate hydrogen by
photoelectrocatalytic water splitting The system also incorporated an analysis-detection system The system
was composed of a photoelectrocatalytic water-splitting hydrogen generation device constructed from TiO2
nanorods (water splitting) a platinum cathode and a AgAgCl reference electrode submersed in a 05 M
Na2SO4 solution Results from five tests of the system were reported After the first hour the device produced
17-20 micromolh hydrogen for four hours as determined by the inbuilt detector76
(TRL 3)
324 Future development main challenges
The generation of electricity from solar energy by PVs has been successfully commercialised with the most
recent solar projects being able to produce electricity at a cost of 015 ndash 035 $kWh on a megawatt scale31
Facilities such as the Solar Star Power Station and the Topaz Solar Farm in the USA are examples of facilities
that use PV technologies that are capable of producing electricity (TRL 8-9) These facilities can now be
constructed because the cost of PVs has dramatically decreased and their efficiencies have increased over
the last few years Laboratory research is currently focused on further increasing the efficiency of PVs and
combining these systems with catalysts that are capable of generating higher order hydrocarbon fuels
However the reduction of carbon dioxide to liquid fuels is a complicated multi-electron process still in the
proof-of-concept stage (TRL 2-3) It is also recommended that the new materials PVs are constructed from
should ideally be cheap abundant lightweight flexible and robust If all of these requirements are met the
costs associated with manufacturing PVs as well as transporting installing and maintaining them may
continue to fall
There are a number of general challenges facing PEC technologies (including suspensions of photoactive
nanoparticles and PECs) that are associated with
Effectively designing facilities
Developing methods to store the generated energy
Developing transportation networks to distribute the energy
A major drawback of these facilities is that they can only be used during daylight hours when there is a clear
sky This highlights the importance of being able to store large amounts of energy at these facilities that can
be used outside of daylight hours It has been proposed that the energy generated from these facilities could
be stored in new types of batteries or as chemicals such as hydrogen and hydrocarbons Storing the energy
in the form of hydrocarbons would be particularly useful as these have a much higher energy density than
batteries and hydrogen The infrastructure to store and transport these already exists for them to be used as a
fuel However as previously mentioned the ability to convert hydrogen and carbon dioxide into high order
hydrocarbons using PVs and PECs is still in the proof-of-concept stage10
46
There are also a number of challenges related to the materials used to construct photoactive nanoparticles
and PECs This is particularly problematic because the most useful semiconductors are not stable in water
and the metal oxides that are stable in water often have band gaps that are too large for light absorption1065
There are three main processes that cause electrodes to degrade over long periods of time and inhibit their
activity
The first is corrosion which occurs with all materials over long periods of time
The second is catalyst poisoning which is caused by the introduction of solution impurities and it has
been shown that low concentrations of impurities can have a huge impact on electrode efficiency77
Finally changes to the composition and morphology (structurestructural features) of the electrode can
decrease their efficiency30
As well as exhibiting high stability the materials have to be highly efficient However there is a relationship
between device complexity cost and efficiency Water-splitters using triple-junction amorphous silicon or IIIndashIV
semiconductors have good efficiencies (5-10) but have high costs and device complexities Simpler
approaches using oxide-based semiconductors in a dual-absorber tandem approach have reported STH
conversion efficiencies up to 0368
This highlights the need to find cheaper and efficient semiconductor
materials that can be used for the water-splitting reaction
The US Department of Energy has determined that the price of hydrogen production delivery and dispensing
must reach $2-3 kg-1
before it can compete with current fuels2 It is also important to take into account the
infrastructural changes that would be required if we were to adopt a hydrogen fuel economy To meet the
current power demands of the US with PVs that have an efficiency of 10 a total area of 58000 miles2 would
be required The cost of semiconductors capable of these efficiencies amounts to tens of trillions of dollars
not taking into account the huge costs associated with the required changes to the infrastructure32
These
facilities would only be viable in areas where there is an abundance of sunshine (such as deserts) which also
proposes large fuel transportation issues In the majority of areas the sun is intermittent and only provides
about 6-10 hours of sunshine per day This further highlights the need to be able to store the energy in the
form of chemical bonds that can be used at any time as well as be more easily stored as batteries can only
store a relatively small amount of the energy required and can produce large quantities of toxic materials when
manufactured
It has been calculated that for the water-splitting reaction to provide one third of the energy required by the
human population in 2050 10000 solar plants each covering a 5 km x 5 km area (250000 km2 = 1 of the
Earthrsquos desert area) and with an overall efficiency of 10 would be required Each plant would be capable of
generating ca 570 tonnes of hydrogen from 5100 tonnes of water per day which together could provide up to
33 of the energy needed by mankind in 2050 The hydrogen could be transported directly to on-site
chemical plants where other organic compounds can be manufactured4 Figure 3 shows two diagrams of one
of these sites that could be capable of producing 570 tonnes of hydrogen per day24
The amount of each
material needed to generate methane from hydrogen and carbon dioxide is given in the formula below in
tonnes The US Department of Energy has set a target for hydrogen-producing PEC devices to have an STH
efficiency of 10 and a 5000 hour durability by 201878
120784119815120784 + 119810119822120784 rarr 119810119815120786 + 119822120784
120784(120784120790120787) + 120788120784120789120782 rarr 120784120784120790120782 + 120786120787120788
According to these calculations 6270 tonnes of carbon dioxide would be required by each of these plants per
day to use all of the hydrogen generated to produce 2280 tonnes of methane and 4560 tonnes of oxygen
The amount of carbon dioxide required increases linearly as the hydrocarbon chain length increases The cost
of manufacturing the number of PEC cells required to carry out this amount of water splitting would be in the
tens of trillions of euros taking into account the current costs of the associated technology62
The energy
required to power these facilities would be obtained from renewable sources such as wind wave and PVs
47
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting photoelectrochemical cells H2 generated
on-site could be used to reduce CO2 to higher order hydrocarbon fuel molecules These figures were constructed by Maeda
et al 2010 and Tachibana et al 2012
33 Co-electrolysis
331 Description of the process
Electrolysers capable of conducting the water-splitting reaction have existed for centuries Water electrolysers
are capable of converting water and DC electricity into gaseous hydrogen and oxygen according to the
equation below879
High-pressure (30 bar) water electrolysers have been commercially available since 1951
In 2012 there were at least 13 manufactures that produce low temperature water electrolysers (3 using
polymer electrolyte membranes (PEM) and 3 using alkaline electrolysers)79
Electrolysers that use solid oxide
electrolysers cells (SOECs) under high temperatures were first developed in the 1980s in the HotElly project
Currently SOEC technologies are still in the research and development stage It should also be noted that the
water splitting thermodynamics are more favourable at the higher temperatures used in SOECs as compared
to alkaline electrolysers PEMs and PECs ΔG = 237 kJ mol-1
(123 eV) at ambient temperatures ΔG = 183 kJ
mol-1
(095 eV) at 900 oC
8397980
120784119815120784119822 + 119811119810 rarr 120784119815120784 + 119822120784
Co-electrolysis is a technique that can be used to produce fuel molecules directly from electricity water and
carbon dioxide Interest in the electrolysis of water and carbon dioxide originated in the 1960s where it was
thought that the process could be used to supply oxygen for submarines and spacecraft81
Unlike electrolysis
co-electrolysis aims to simultaneously split water and reduce carbon dioxide to form a mixture of carbon
monoxide (CO) hydrogen and oxygen this process is highlighted in the equation below The term ldquosyngasrdquo
(synthesis gas) refers to a mixture of carbon monoxide and hydrogen and not the oxygen component
Producing fuels by co-electrolysis consists of three main stages carbon dioxide capture syngas synthesis
and storage of the renewable energy as chemical bond energy (hydrogen and hydrocarbon fuels)80
This
chemical reaction is achieved by using high temperature solid oxide cell electolysers3982-84
Co-electrolysis
offers a number of advantages over solar and wind power farms Solar and wind power farms have to be built
in site-specific areas to maximise their power output which limits the number of countries that would be able
to host these technologies (solar power is only viable for countries that have high levels of sun year-round)
Solar and wind power farms are only able to generate power intermittently which makes them unsuited to
coping with sudden large power demands (solar farms can only generate power during daylight hours) It has
been suggested that batteries and thermal fluids could be used to store energy for peak times However
48
these storage methods are currently unable to store large amounts of energy suffer from short lifetimes and
generate large amounts of harmful waste during production531
Technologies capable of co-electrolysing
water and carbon dioxide to syngas and hydrocarbons are at an early stage of development TRL 2-4
119810119822120784 + 119815120784119822 rarr 119810119822 + 119815120784 + 119822120784
It is also important to note that all electrolysers require a large input of electrical energy which would have to
be from renewable sources if this technology is to relieve its dependence on fossil fuels The major cost
associated with solid oxide electrolysis cells (SOEC) comes from the electricity required to operate them and
the feedstock while the cost of the electrolyser material makes up a smaller proportion of the total cost39
If
SOECs were designed to utilise wind and solar energy (PVssemiconductors) to generate the electricity they
require their operating costs would decrease significantly However this also decreases the number of
countries that could host electrolysers as their operation is again dependent on solar and wind energy It
would also be advantageous to incorporate a Fischer-Tropsch process that is capable of generating synthetic
hydrocarbons from the resulting syngas that can be used in the existing infrastructure3985
Syngas can be used to generate simple intermediate compounds that can be used as feedstock for more
complicated chemicals such as fertilisers pharmaceuticals plastics and synthetic liquid fuels Methanol is an
example of a simple molecule that can be made from syngas The dehydration of methanol can be used to
generate the cleaner fuel dimethyl ether which is being considered as a future energy source40
The most
common feedstocks for the production of hydrocarbon fuels are fossil fuels and biomass However it is hoped
that sustainable feedstocks such as carbon dioxide and water can be used to generate syngas which can be
converted into hydrocarbon fuels through Fischer-Tropsch synthesis39
Illustrations
Figure 37 A schematic diagram of water electrolysis being conducted in an alkaline electrolyser (left) and a polymer electrolyte
membrane electrolyser cell (right) to produce hydrogen and oxygen from water and DC electricity This figure was originally
produced by Carmo et al 20138
49
Figure 38 A schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell that produces hydrogen and
oxygen from water and DC electricity the reactions that occur at the electrodes are also shown This figure was adapted
from Meng Ni et al 20085
Explanations
Alkaline water electrolysis has been a mature technology for over 100 years (there were over 400 units in
operation by 1902) They have high efficiencies (47-82) and long lifetimes (15 years)1186
A recent
publication by Ursuacutea et al 2012 compiled a list of the main manufacturers of alkaline water electrolysers which
is shown in Table 3211
A number of advancements have been made regarding alkaline electrolysers over the last few years which
have focused on improving their efficiency to reduce operating costs and have increased the operating
current densities11
Other advancements include
Minimising the space between the electrodes to reduce the ohmic losses and allow the cell to operate at
current densities
Developing new materials to replace older diaphragms which exhibit higher stability and are better at
facilitating ion transport
Developing high-temperature (ca 150 oC) alkaline water electrolysers to increase the electrolyte
conductivity and promote the kinetics of the electrochemical reactions at the electrodesrsquo surface
Developing new electrocatalytic materials to reduce the electrode over-potentials this present a particular
difficulty for the anode because the oxidation half-reaction is most demanding
Alkaline electrolysers (Figure 3 left) consist of two electrodes that are separated by a gas-tight diaphragm
submersed in an electrolyte solution containing a high concentration of potassium hydroxide (20-30 wt) It
should be noted that electrolytes such as sodium hydroxide and sodium chloride can also be used in some
systems and they usually operate between 40-90 oC
11 Water is reduced at the cathode to generate hydrogen
gas and hydroxide ions (OH-) which diffuse through the diaphragm to the anode where they recombine to
generate oxygen and water811
The hydrogen and oxygen produced by alkaline electrolysers have purities
gt99
In PEM electrolysers (Figure 3 right) the electrolyte is constructed from a polymeric membrane with a cross-
linked solid structure permitting a compact system with greater structural stability (able to operate at higher
temperatures and pressures)8 The electrodes used in PEM electrolysers are usually constructed from noble
metals such as platinum and iridium which limits the scope of this technology as noble metals are of limited
abundance and expensive The unit consisting of the electrodes and polymer membrane is submersed in
water Water oxidation occurs at the anode where oxygen is formed and protons are transferred through the
50
polymer membrane to the cathode where they are reduced to hydrogen PEM electrolysers are able to
produce hydrogen and oxygen of even higher purity than alkaline electrolysers at ca 9999
It should be noted that the materials needed for the electrolyte and electrodes have to be cheap and easy to
manufacture on a large scale5 Water in the gas phase diffuses into the porous cathode where it dissociates
into hydrogen and oxygen at reaction sites81
At this point the hydrogen diffuses out of the cathode and is
collected The oxygen ions are transported through the electrolyte solution to the porous anode where they
are oxidised to oxygen and collected this process is demonstrated in Figure 35 The material chosen for the
cathode has to be able to support the diffusion of steam the reduction of steam and the diffusion of hydrogen
These requirements limit the number of suitable materials that can be used to noble metals such as platinum
and gold and non-precious metals such as copper and nickel However like the artificial photosynthetic
systems previously discussed the use of noble metals is unfavourable due to their rarity and high costs The
anode has to be chemically stable under similar conditions to the cathode which means that noble metals are
again candidate materials along with electronically-conducting mixed oxides5
Electrolyte This must be a chemically stable dense gas-tight material with good ionic conductivity and
low electronic conduction The electrolyte has to be stable enough to withstand the high temperatures
associated with the chemical reactions taking place It has to be gas-tight to limit the recombination of
protons and O- to hydrogen and oxygen respectively The electrolyte should also be as thin as possible so
as to minimise the ohmic overpotential5
Electrodes It should be noted that the following properties are the same for both the anode and cathode
The electrodes have to be porous enough to allow the transportation of hydrogen and oxygen and need to
have a similar thermal expansion coefficient to the electrolyte so as to limit the amount of mechanical
stress the components exert on each other They must also be chemically stable in highly
oxidisingreducing environments and high temperatures5
To ensure that the SOEC is operating at its maximum efficiency a number of parameters need to be
quantified this is often done through modelling the system Some of the parameters measured include the
composition of the cathode inlet gas cathode flow rate and cell temperature39
When generating syngas in a
SOEC the carbon dioxide is fed into the cathode side of the device where the hydrogen is generated
51
Table 32 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the performance data for each device This table was originally constructed by Ursua et al 201211
Manufacturer
Technology
(configuration)
Production
(Nm3h)
Rated Power
(kW)b
Energy
Consumption
(kWhNm3)c
Efficiency
()d
Maximum
Pressure
H2 purity
(vol)
Location
AccaGen Alkaline (monopolar) 1-100 67-487 6-487 528-727 10 999 Switzerland
Avalance Alkaline (bipolar) 04-36 2-25 543-5 652-708 448 na USA
Claind Alkaline (bipolar) 05-30 na na na 15 997 Italy
ELT Alkaline (bipolar) 3-330 138-1518 46-43 769-823 1 998-999 Germany
ELT Alkaline (bipolar) 100-760 465-3534 465-43 761-823 30 993-998 Germany
Erredue PEM (bipolar) 06-213 36-108 6-51 59-698 25-4 993-998 Italy
Giner Alkaline (bipolar) 37 20 54 655 85 na USA
Hydrogen Technologies Alkaline (bipolar) 10-500 43-2150 43 823 1 999 Norway
Hydrogenics PEM (bipolar) 10-60 54-312 54-52 655-681 10 999 Canada
Hydrogenics Alkaline (bipolar) 1 72 72 492 79 9999 Canada
H2 Logic Alkaline (bipolar) 066-4262 36-213 545-5 649-708 4 993-998 Denmark
Idroenergy Alkaline (bipolar) 04-80 3-377 75-471 472-752 18-8 995 Italy
Industrie Haute Technology Alkaline (bipolar) 110-760 5115-3534 465-43 761-823 32 998-999 Switzerland
Linde Alkaline (bipolar) 5-250 na na na 25 999 Germany
PIEL division of ILT Technology Alkaline (bipolar) 04-16 28-80 7-5 506-708 18-8 995 Italy
Proton OnSite PEM (bipolar) 0265-30 18-174 73-58 485-61 138-15 99999 USA
Sagim Alkaline (bipolar) 1-5 5-25 5 708 10 999 France
Teledyne Energy Systems Alkaline (bipolar) 28-56 na na na 10 99999 USA
Tredwell Corporation PEM (bipolar) 12-102 na na na 75 na USA
52
332 Current status review of the state of the art
This section will focus on the advancements that have recently been made in regards to SOECs Much of the
research being conducted on SOECs is focused on increasing the efficiency and stability of the electrolyte and
electrodes by changing the temperature the SOECs operate at gas mixtures and the materials the cells are
constructed from
The most common electrolyte material used in SOECs yttria-stabilised zircona (YSZ) due to it having a high
thermal stability high oxygen ion conductivity and low cost To generate YSZ zirconia (ZrO2) can be doped
with compounds such as Y2O3 and Yb2O3 to improve the stability and conductivity Sc2O3 can also be used to
generate scandia-stabilised zirconia (ScSZ) Other co-dopants such as TiO2 and Al2O3 can be added to
further enhance the stability587
Scandium stabilised zirconia (ScSZ) has a higher conductivity than YSZ but
is not as widely used due to the high costs associated with it It should also be noted that the dopant
concentration has to be of a specific amount in order to ensure the conductivity is at its maximum It has been
shown that different dopant concentrations change the lattice structure of the ZrO2 over time which leads to
the decrease in conductivity5 The dopant chosen for the SOEC is also dependent on the temperature the cell
will have to operate at as the dopant will change the conductivity of the electrolyte at different temperatures
Researchers recently investigated the effect temperature (550 oC ndash 750
oC) had on the performance of SOEC
cells with the following layout a Ni-YSZ support layer (680 microm) a Ni-ScSZ cathode-active layer (15 microm) a
ScSZ electrolyte layer (20 microm) and a LSM-ScSZ anode layer (15 microm) The performance of the cell was
observed to decrease with decreasing temperature when the same gas composition was used (143 CO
286 H2O and 571 Argon) As the temperature decreased the ionic conductivity of the electrolyte layer
decreased The mass transfer was the rate-determining step for the electrodes at temperatures lt750 oC
Methane was only detected in the gas products when the input gas composition was the same as above the
cell temperature was lt700 oC and the operating voltage was gt 2 V
81 (TRL 3)
Electrolyte materials such as ceria- and LaGaO3-based electrolytes are showing promise at intermediate
temperatures when they are doped with other compounds that increase their ionic conductivity79
Recently
researchers developed SOEC capable of steam and carbon dioxide co-electrolysis The cell was constructed
from Ni-YSZ (nickel-yttria-stabilized zirconia) solid oxide cell with a bi-layered ScSZGDC electrolyte structure
and a LSCF (lanthanum strontium cobalt ferrite) oxygen electrode When the device was operated at 800 oC
the cell exhibited a high electrolysis current density of about 22 A cm2 and 19 Acm
2 in steam and carbon
dioxide electrolysis respectively The structural integrity of the cell was checked after the experiment and no
cracking or delamination of the electrolyte or the electrolyteelectrode was observed88
(TRL 4)
Researchers were recently able to directly synthesise methane by co-electrolysing carbon dioxide and water
to form carbon monoxide and hydrogen then conducting Fischer-Tropsch synthesis in tubular solid oxide
electrolysis cells7 As previously discussed the reduction of water in SOECs requires very high temperatures
(ca 800 oC) however with the Fischer-Tropsch process lower temperatures (ca 250
oC) are required Using
the experimental setup shown in Figure 3 researchers were able to achieve a methane yield of 1184
which means that 41 of carbon dioxide is converted to methane over the course of the 24-hour test7 The
equipment consists of a SOEC tube with a hole running through its length while the wall of the tube consists
of three layers that are structured in a similar fashion to that shown in Figure 3 it consists of an anode an
electrolyte and a cathode The first section of the SOEC tube is heated to 800 oC to allow syngas to be
generated after which the tube cools over a gradient to 250 oC to allow methane production to take place
(TRL 4)
53
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis cell electrolysers This table
was originally constructed by Carmo et al 20138
Alkaline Electrolysis PEM Electrolysis SOEC Electrolysis
Advantages
Well-established technology High current densities Efficiency up to 100
Non-noble metal catalysts High voltage efficiency Efficiency gt 100
Long-term stability Good partial load range Non-noble metal catalysts
Relative low cost Rapid response system High pressure operation
Stacks in the megawatt range Compact system design
Cost effective High gas purity
Dynamic operation
Disadvantages
Low current densities High cost of components Laboratory stage
Crossover of gases Corrosive environment Bulky system design
Low partial load range Low durability Low durability
Low dynamics Stacks below megawatt range Little costing information
Corrosive electrolyte
Figure 39 A schematic diagram of co-electrolysis and the Fischer-Tropsch process being conducted in a tubular solid oxide
electrolyser that is able to produce CH4 This figure was originally generated by Chen et al 20147
333 Patents
The cell was composed of separate anode and cathode chambers separated by a membrane that allows the
transport of sodium ions (Na+) the anode and cathode chambers are in contact with water Oxygen is
collected in the anode chamber and hydrogen is collected in the cathode chamber following which hydrogen
and carbon dioxide are reacted together to generate syngas and oxygen as by-products that need to be
separated The electrode materials were described as being ceramic that could be doped with a catalyst
material such as cobalt cerium europium or cadmium combinations of these elements were also permitted89
(TRL 3)
A patent was filed in 2011 detailing a design for SOEC that could co-electrolyse steam and carbon dioxide to
produce syngas The cell consisted of a cathode composed of nickel-zirconia an anode consisting of
strontium doped lanthanum manganite and the electrolyte between the two electrodes was composed of
yttria-stabilised zirconia the whole cell was designed to operate between 800-1000 oC The authors stated
that the electrical power to run the device would be sourced from nuclear power however it should also be
possible to run this device off solar energy This device operated with the carbon dioxide being fed into the
cathode section where the hydrogen is generated90
(TRL 4)
54
A patent was filed in 2013 detailing a modified anodeelectrolyte structure for a solid oxide electrochemical
cell where the role of the anode is to react with fuel (steamhydrocarbons) The cathode (when in SOEC
mode) consisted of a backbone of electronically conductive perovskite oxides selected from the group
consisting of niobium-doped strontium titanate vanadium-doped strontium titanate and tantalum-doped
strontium titanate mixtures were also permitted The electrolyte material consisted of a scandia and yttria-
stabilised zirconium oxide91
(TRL 2-3)
334 Future development main challenges
Technologies that are capable of electrolysing water cover a variety of TRLs wherein alkaline and PEM
electrolysers used to generate hydrogen by the water-splitting reaction have TRLs 7-8 as they have been
commercialised can be purchased and can produce power at the low megawatt scale However they are
currently not a viable option to generate power at the megawatt scale Newer SOEC technologies currently
being developed have lower TRLs (3-5) but are showing great promise in that their efficiencies are high and
they are cheap to produce
Technologies capable of co-electrolysing water and carbon dioxide to syngas are at an early stage of
development - TRLs 2-4 Research is still focused on studying how cell conditions can be manipulated to
optimise the production of syngas and hydrocarbons Research is also focused on improving the long-term
stability of the electrolytes and electrodes used in SOECs by investigating new materials and cell designs that
are cheap and easy to construct It will also be necessary to conduct duration experiments In terms of their
commercial viability they are far behind PVs at roughly the same stage as PEC technologies and ahead of
synthetic biology systems
SOECs could prove to be an efficient method by which electrical energy generated from renewable sources
(wind and solar) could be stored in the form of chemical bonds To date it has been proven that syngas can
be generated from SOECs and that methane can also be generated within the same system through a
Fischer-Tropsch process More research is needed that aims to improve the efficiency by which methanol can
be generated and to determine whether more complex hydrocarbons can be synthesised
The success of this technology is likely to be dependent on how well systems that generate electricity from
renewable sources can be integrated within it It has been suggested that nuclear wind and solar power
stations could be used to provide the electrical power required This would help to lower the cost of this
technology as sourcing the electricity needed is one of the major costs It should be noted that one of the
most commonly cited advantages of this technique over solar and wind power is that it is not site-specific
However if solar and wind power were to be used to generate the electricity needed for this technology then
it becomes a site-specific technology again This is also a problem for PEC-cell-based technologies
34 Summary
The aim of this brief literature review was to highlight the advancements that have been made across the main
technologies within artificial photosynthesis discuss some of the most recent technological solutions that have
been developed in these areas and identify the main challenges that need to be addressed for each
technology before they can be commercialised
Synthetic biology amp hybrid systems
Synthetic biology amp hybrid artificial photosynthetic systems are currently capable of producing small amounts
of fuel molecules such as hydrogen and simple hydrocarbons The majority of the technologies in this
category are at the research and development stage (TRL 1-4) To date there are no large scale plans to
produce solar fuels at a commercial level using this technology It should be noted that synthetic biology amp
hybrid systems are currently used to produce fine chemicals at the commercial level but these are not needed
55
in the large quantities in which solar fuels are required It is currently too early to comment on the long-term
commercial viability of this technological pathway however the research in this area is progressing quickly
and as our fundamental understanding of biological systems increases progression is promising It should be
noted that these systems are becoming efficient enough to produce hydrogen at a rate that is comparable to
that which occurs in natural photosynthesis on a small laboratory scale
Photoelectrocatalysis of water (water splitting)
PVssemiconductors are the most advanced technology discussed in this report as they have been
commercialised and are able to generate electricity on a MW scale at facilities such as the Solar Star Power
Station and the Topaz Solar Farm31
PVssemiconductors are used in PEC technologies where they are
incorporated into the cell design and act as light absorbers Instead of the energy gained from light absorption
being used to generate electricity directly it is used to generate fuel molecules such as hydrogen from the
water-splitting reaction The hydrogen generated from this process can then be stored and used at a later time
to provide energy This is useful because PVs are only able to generate power intermittently during daylight
hours There are many examples of photoelectrocatalysis being carried out by PECs as well as suspensions
of photoactive nanoparticles and the majority of the technologies have a TRL 2-4 However it should be noted
that PVsemiconductor technologies that generate electrical power have TRL 8-9 The main challenges facing
this technology involve developing materials that have high STH efficiencies are cheap to manufacture and
are stable for long periods of time Calculations have been performed to determine the efficiencies associated
with multiple reactor plant designs These have shown that it is theoretically possible to generate large
quantities of hydrogen however that it could cost trillions to generate a significant amount of hydrogen with
current technology
Co-electrolysis
Water electrolysers such as alkaline and PEM electrolysers are considered mature technologies that have
been commercialised and have TRLs 7-8 They can be purchased and can produce power at the low
megawatt scale However they are currently not a viable option to generate power at the megawatt scale
Newer SOEC technologies that are currently being developed have lower TRLs 3-5 but are showing great
promise in that their efficiencies are high and they are cheap to produce Technologies that are capable of
generating syngas and some organic products by a Fischer-Tropsch process are in the research and
development stage (TRL 3-4) Research is currently focused on determining how SOEC conditions can be
manipulated to increase efficiency as well as identifying more stable durable and efficient compounds to
incorporate into the cell design The incorporation of SOECs into large scale solar and wind farms could prove
to be an efficient method by which electrical energy can be stored as chemical energy
The technologies discussed above show great potential in being able to convert solar energy into solar fuels
They are still in the early research phase but all technologies made significant improvements in efficiencies
lifetimes and the number of products they can produce other than hydrogen It is likely that PVs will be used to
absorb solar energy to generate electricity for SOECs or forms part of a PEC cell that generates fuel
molecules It should be noted that wind power could be used to provide the electricity needed for SOECs to
operate which would allow these systems to be used outside of desert regions Biological systems currently
look to be less suitable for producing large quantities of fuel molecules partly due to their early research stage
but may prove to be useful in generating highly complicated molecules once the understanding of protein
engineering has increased
All of these technologies seek to improve device lifetimes increase efficiency lower manufacturing costs and
increase the scope of synthetic fuels that can be produced Switching to a hydrogen economy will require
large and expensive infrastructure changes Using hydrogen to generate more complex fuel molecules will
require more research however ultimately fewer infrastructure changes
57
4 Mapping research actors
41 Main academic actors in Europe
In Europe research on AP is conducted by individual research groups or in research networks or consortia
Most of the research groups are located in Germany the Netherlands and Sweden The largest country-based
networks are also in Sweden and in the UK Most of Germanyrsquos research groups are part of the pan-European
AP network AMPEA The number of research groups has increased substantially since the 1990s when the
field became more prominent coupling with the (exponential) rise of publications in AP3
411 Main research networkscommunities
In this section we describe the main research networkscommunities on artificial photosynthesis in Europe
Under networks we indicate co-operations with multiple universities research organisations and companies
Instead of focusing strictly on major integrated research on specific AP topics the networks mostly have a
broad research and collaboration focus Larger joint programmes exist but are more focused on various key
priorities in Europe for different research areas such as AMPEA (Advanced Materials and Processes for
Energy Application) which is one of the joint programmes of EERA (European Energy Research Alliance) of
which artificial photosynthesis is one of the three identified applications The first national research network
dedicated to artificial photosynthesis was the Swedish Consortium for Artificial Photosynthesis (CAP)
following which a number of other national and pan-European networks emerged in the past few years
Research networks and communities play an important role in facilitating collaboration across borders and
among different research groups The development of AP processes needs expertise from molecular biology
biophysics and biochemistry to organometallic and physical chemistry Research networks provide the
platform for researchers and research teams from those diverse disciplines to conduct research together to
create synergistic interactions between biologists biochemists biophysicists and physical chemists all
focusing on questions relevant for AP and solar fuels This need for research coordination is reflected by the
fact that the Swedish Consortium for AP was a bottom-up initiative by university-based scientists4
Furthermore networks are effective for promoting AP research and raising public awareness and knowledge
about AP5
Networks and consortia with industrial members also play an important role with respect to the goal of turning
successfully developed AP processes into a commercially viable product Research and innovation in
materials and processes of AP can be backed up by private innovation and investments Feedback on the
applicability of research outputs can be incorporated and shape further research efforts and application
possibilities in the business sector can be discovered
The advantages and synergy effects of network membership for research groups are reflected in the fact that
more than 50 of European research groups are part of a research network in Europe The consortia vary in
their membership and their funding sizes whereas about 400 researchers are affiliated with the pan-European
consortium AMPEA the Swedish CAP unites about 80 scientists Furthermore it is apparent that only AMPEA
is a truly pan-European consortium member research groups come from various European countries such as
Austria France Czech Republic Germany Italy the Netherlands Norway Spain Sweden Switzerland and
3 V Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in
ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press) conducted a bibliometric analysis using key words related to the field of artificial photosynthesis showing that only a few papers were published before the 1990s reaching more than 900 publications in 2014
4 httpwwwsolarfuelse
5 httpsolarfuelsnetworkcomoutreach
58
the UK Most of the other consortia discussed below are based in a specific country which is reflected in their
affiliations among research groups
EU - AMPEA
The European Energy Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials
amp Processes for Energy Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging
Technologies and artificial photosynthesis became the first energy research subfield to be organised within
AMPEA The goal of this joint programme which was launched at the end of 2011 is to set up a thorough and
systematic programme of directed research which by 2020 will have advanced to a point where commercially
viable artificial photosynthetic devices will be under development in partnership with the industry Its goal to
boost research on a pan-European basis is reflected in the fact that to date more than 40 European scientific
institutions participate Many institutes in different Member States are associated with AMPEA (31 full
members for example CEA DIFFER TU Delft JKU Max Planck Institute)6 The research efforts of the
AMPEA participants aim at advancing all of the three identified pathways of artificial photosynthesis Due to
the low availability of efficient molecular catalysts based on earth-abundant elements the search for those
elements and the development of such catalysts constitute the early research focus
Italy ndash SOLAR-CHEM
In 2009 the universities of Bologna Ferrara and Messina founded SOLAR-CHEM the Italian inter-university
centre for the chemical conversion of solar energy7 Later on other universities in Italy also joined SOLAR-
CHEM The research efforts of the centre aim to foster research in solar fuels through a multidisciplinary
approach and coordination activities eg through the organisation of dedicated events and through short-term
exchanges of staff in the network
Netherlands ndash BioSolar Cells
The Dutch BioSolar Cells public-private partnership was established in 2010 BioSolar Cells is a cooperation
of 10 knowledge institutions such as Leiden University Delft University of Technology and the University
of Twente8 as well as 45 private industries
9 The programme is funded by FOMALWNWO the Dutch
ministry of Economic Affairs Agriculture and Innovation many companies and a number of Dutch universities
and research organisations The BioSolar Cells programme has three themes artificial photosynthesis
photosynthesis in cellular systems and photosynthesis in plants These three research themes are
underpinned by a fourth theme education and societal debate where educational modules are developed to
equip and inspire future researchers policy makers and industrialists and where the societal consequences
of new solar-to-fuel conversion technologies are debated10
Sweden - CAP
Founded in 1994 the Swedish Consortium for Artificial Photosynthesis carries out integrated basic
research with the goal to produce applicable outcomes such as fuel from solar energy and water Their
projects integrate two topics artificial photosynthesis in man-made systems to make hydrogen from sun and
water and photo-biological fuel production in living organisms They focus on photoelectrocatalysis as the
technology pathway yet are also building on their research on the principles of natural photosynthesis for
energy production A unique component in the consortium is hence the synergistic interactions between
biologists biochemists biophysicists and physical chemists all focusing on questions relevant for solar
fuels11
The academic partners come from Uppsala University Lund University and the KTH Royal
Institute of Technology in Stockholm
6 httpwwweera-seteueera-joint-programmes-jpsadvanced-materials-and-processes-for-energy-application-ampea
7 httpswwwsocchimitsitesdefaultfileschimindpdf2012_6_88_capdf
8 httpwwwbiosolarcellsnlover-biosolar-cellsnew_page_1html
9 httpwwwbiosolarcellsnlover-biosolar-cellsbedrijvenhtml
10 httpwwwbiosolarcellsnlonderzoek
11 httpwwwsolarfuelsesolar-fuels
59
UK ndash SolarCAP
The SolarCAP Consortium for Artificial Photosynthesis is a consortium of four UK academic research groups
funded by the Engineering and Physical Sciences Research Council The groups based in the Universities
of East Anglia Manchester Nottingham and York12
are specifically exploring the solar conversion of
carbon dioxide to carbon monoxide in tandem with the conversion of methane or alkanes to useful oxygen-
containing products such as alcohols They are exploring the second technological pathway of
photoelectrocatalysis
UK ndash Solar Fuels Network
Solar Fuels Network brings together academic and industrial researchers in solar fuels and artificial
photosynthesis It aims to develop an effective community of solar fuels researchers from both academia and
industry to raise the profile of the UK solar fuels research community nationally and internationally Through
this it aims to promote collaboration and co-operation with other research disciplines industry and
international solar fuels programmes and to contribute towards the development of a UK solar fuels
technology and policy roadmap The networkrsquos management team is based at Imperial College London and
is led by Prof James Durrant Partner organisations encompass the Royal Society of Chemistry the Energy
community of the Knowledge Transfer Network (KTN) the Solar Fuels Institute (SOFI) and the Foreign and
Commonwealth Officersquos Science and Innovation Network13
In other countries across Europe national initiatives have emerged in the last few years and more are
expected to in the future For example the Photoelectrochemistry Competence Center (PECHouse and
PECHouse2)14
under coordination of the Ecole Polytechnique Federale de Lausanne (prof Michael Graumltzel)
has been created in Switzerland while in France artificial photosynthesis is being researched by laboratories
of excellence (LabEx Arcane15
and LabEx Charmatt16
)
412 Main research groups (with link to network if any)
A list of the main research groups in Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire Artificial
Photosynthesis community Taking that into account the numbers presented below may provide an indication
of the AP research sector as a whole
Table 41 Number of research groups and research institutions in European countries
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Austria 1 1 15
Belgium 1 1 -
Czech Republic 1 1 -
Denmark 3 2 -
Finland 1 1 6
France 5 3 14
Germany 31 17 16
Ireland 1 1 7
Italy 5 5 29
Netherlands 28 9 18
Norway 1 1 -
12
httpwwwsolarcaporgukresearchgroupsasp 13
httpsolarfuelsnetworkcommembership 14
httppechouseepflchpage-32075html 15
httpswwwlabex-arcanefrencontentlaboratoires-excellence-arcane 16
httpwwwcharmmmatfrindexphp
60
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Spain 4 4 11
Sweden 13 5 17
Switzerland 5 5 10
UK 13 9 10
Total 113 65 15
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 66 main research institutions and universities working on artificial photosynthesis in Europe
Those research institutions contain 113 individual research groups with an average size of about 15
people17
The sizes of research groups can vary widely from for example 80 members of a research group at
Imperial College London to only two persons in the research group of Klaus-Dieter Weltmann at the Leibniz
Institute for Plasma Science and Technology The country with both the highest number of involved institutions
and research groups is Germany where 32 individual research groups in 17 research institutions are active
Germany is followed by the Netherlands with nine institutions and 28 research groups and by Sweden with
five institutions and 13 research groups Almost half (47) of the research groups focus on the second
pathway ie photoelectrocatalysis whereas 36 research the first pathway ie the usage of synthetic
biology and hybrid systems to produce fuel molecules and about 17 follow the third pathway in their
research which is co-electrolysis A bulk of the research in most countries is done on the second pathway
except for in Sweden and Finland which seem to specialize in exploring the first pathway Table 42 provides
an overview of some of the key statistics the number of research groups and research institutions in AP per
country and the number of research groups focusing on each of the three technological pathways
respectively
Table 42 Number of research groups per research area (technology pathway)
Country Total Synthetic biology
amp hybrid systems
Photoelectrocatalysis Co-electrolysis
Austria 1 1 1 0
Belgium 1 1 1 0
Czech Republic 1 0 1 0
Denmark 3 0 2 2
Finland 1 1 0 0
France 5 2 5 0
Germany 31 14 15 9
Ireland 1 1 1 0
Italy 5 0 5 0
Netherlands 28 12 17 9
Norway 1 0 1 0
Spain 4 2 3 1
Sweden 13 10 7 0
Switzerland 5 1 5 3
UK 13 8 5 1
Total 113 53 69 25
Source Ecorys
17
The average group size is derived from survey responses and available information on the websites of the groups
61
In the following section our findings have been illustrated by presenting some of the main research institutions
and their research groups
Germany - Helmholz Zentrum Berlin
The Institute for Solar Fuels of the HZB is led by Prof Roel van de Krol The institute pursues a strategy to generate
hydrogen via the second technology pathway they combine the energy conversion of light into electrical energy via
photonic stimulation of the semiconductor directly with the catalytic procedures on the electrolyte-electrode-interface for
the conversion into storable chemical energy (hydrogen) The generated hydrogen can then be stored by means of
already known methods (compressed gas liquid-H2 metal hydride conversion to methanol) Their approach combines
research and insights from photo-physics surface- and material chemistry photoelectrochemistry interface- and
surface sciences as well as system alignment18
Therefore they collaborate closely with the University of Messina in
Italy and the Leiden University in the Netherlands Moreover the HZB is also part of the European research network
AMPEA
Germany ndash Max Planck Institute for Chemical Energy
The Department of Biophysical Chemistry at the Max Planck Institute for Chemical Energy focus on the water-oxidizing
enzyme of oxygenic photosynthesis and hydrogenases Their research uses a variety of different physical techniques
to gain insight into enzymatic processes such as into photosynthetic water splitting and (bio)hydrogen production
which can be used for biomimetic chemistry ie to develop catalytic systems in energy research19
They hence focus
on the first and second technology pathways The Max Planck Institute for Chemical Energy also contributes to the
European research network AMPEA
The Netherlands - The Dutch Institute for Fundamental Energy Research
Part of the Netherlands Organisation for Scientific Research (NWO) the DIFFER institute has since its initiation in 2012
grown to an activity of about 65 Meuroyear (about 75 fte) all directed at the production of chemicalsfuels from electrons
and photons In particular as part of its solar fuels research DIFFER investigates the splitting of water into hydrogen
and oxygen using electricity and the reduction of carbon dioxide to carbon monoxide As they are located at TUe
campus in Eindhoven they can easily collaborate and share knowledge with universities universities of applied
sciences and industry The DIFFER institute also contributes to AMPEA
Sweden ndash Uppsala University
Various research teams at Uppsala University cover all three relevant technology pathways for artificial
photosynthesis20
Moreover in 2006 the Swedish Consortium for Artificial Photosynthesis (CAP) founded in 1994 by
three researchers from Uppsala University and one researcher from the University of Stockholm created a new
scientific environment at the Aringngstroumlm laboratory at Uppsala University becoming the base for this consortium
Switzerland ndash ETH Zurich
The Professorship of Renewable Energy Carriers21
performs RampD projects in emerging fields of renewable energy
engineering operates state-of-the-art experimental laboratories offers advanced courses in fundamentalapplied
thermal sciences and produces qualified scientists and engineers with expertise in renewable energy technologies
Regarding solar fuels they focus on solar splitting of H2O and CO2 via thermochemical Redox cycles which
corresponds to the third technology pathway of artificial photosynthesis They are partners in several EU projects
concerning solar-driven hydrogen production such as SOLARJET ndash Solar Production of Jet Fuel from H2O and CO2
and HYCYCLES ndash Solar Water-Splitting Thermochemical Cycle22
18
httpswwwhelmholtz-berlindeforschungoeeesolare-brennstoffeindex_enhtml 19
httpwwwcecmpgderesearchbiophysical-chemistryoverviewhtmlL=1 20
httpwwwkemiuuseresearchmolecular-biomimeticphotosynthesis 21
httpwwwprecethzch 22
httpwwwprecethzchresearchsolar-fuelshtml
62
UK ndash Imperial College London
The research of various research teams of the Imperial College London encompasses the first and second technology
pathways It ranges from research on the oxidising enzyme Photosystem II which has become the focus of attention
because cheap water-splitting catalysts are urgently needed in the energy sector to the development of
photoelectrodes and nanoparticles for solar-driven fuel synthesis based on water splitting of water into hydrogen and
oxygen Collaborations across the Imperial College London are complemented with co-operations across the UK as
part of the UK Solar Fuels Network with the Swiss Federal Institute of Technology in Lausanne (EPFL) UCL and
Cambridge University
The density of research group per country in Europe is presented schematically in Figure 41
Figure 41 Research groups in Artificial Photosynthesis in Europe
Source Ecorys
42 Main academic actors outside Europe
Also outside of Europe research on AP is conducted by individual research groups or in research networks or
consortia Most of the research groups and networks are located in the US and in Japan Whereas US-based
networks sporadically have ties to European research groups the Japanese consortia have exclusively
Japanese members both academic and industrial
421 Main research networkscommunities
Outside of Europe the main networks can be found in the US and in Japan The biggest network is the US
network JCAP (Joint Center for Artificial Photosynthesis) with more than 190 persons linked to the
programme and a budget of $122 million for five years Next in line is the Japanese ARPChem which has
roughly the same budget available for a time span of 10 years
63
Japan ndash ARPChem
The Japanese Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology jointly launched the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem) in November 2012 The aim is to bundle efforts for the next
decade to develop innovative catalysts and other materials that could be used for manufacturing fundamental
chemical substances from water and carbon dioxide by making use of solar power Such substances can be
used as raw materials of plastics synthetic fibres synthetic rubber solvents and other products and are
applicable in all areas of peoples everyday lives The expected budget for the coming decade between 2012
and 2021 amounts to 15 billion yen (euro 122 million)23
The utilisation of catalyst technology requires long-term
involvement and entails high risks in development but is expected to have a huge impact on Japans
economy and society The aim is to achieve independence from fossil resources used as raw materials for
chemical substances while overcoming resource and environmental challenges The consortium consists of
partners from academia industry and the government seven universities amongst them the University of
Tokyo the Tokyo University of Science and the Kyoto University companies such as Mitsubishi
Chemicals Mitsui Chemicals Fuji Films and TOTO and governmental research organizations such as the
National Institute of Advanced Industrial Science and Technology (AIST)
Japan ndash All Nippon Artificial Photosynthesis Project for Living Earth (AnApple)
The All Nippon Artificial Photosynthesis Project for Living Earth (AnApple) is one of the Scientific
Researches on Innovative Areas receiving strong financial support from the Ministry of Education Culture
Sports Science and Technology It was set up in 2012 as a five-year national project Although it is not a
consortium in a narrow sense its scope and research impact are substantial as more than 40 Japanese
leading scientific groups are part of this project It is led by Prof Haruo Inoue from the Tokyo Metropolitan
University further academic partners are amongst others the Tokyo University of Science the Tokyo
Institute of Technology Ibaraki University Ritsumeikan University and Hokkaido University
South Korea ndash KCAP
The Korean Centre for Artificial Photosynthesis (KCAP) was launched at Sogang University in 200924
set up
as a ten-year programme with 50 billion won (about euro40 million)25
It aims to secure a wide range of
fundamental knowledge necessary materials and device fabrication for the implementation of artificial
photosynthesis ie generating liquid fuel and oxygen from water and carbon dioxide using solar energy
through collaborative research with a number of research organisations and companies The Korean partners
comprise 14 professors from 8 universities including Sogang University Yonsei University and the Ulsan
National Institute of Science and Technology and one industry partner Pohang Steel Company26
Foreign academic partners are the Lawrence Berkeley National Laboratory California Institute of
Technology and University of California Berkeley The Centre has ties to other AP networks such as SOFI
and JCAP
US ndash JCAP
In 2010 the Department of Energy created the Energy Innovation Hubs and among them a Joint Centre for
Artificial Photosynthesis (JCAP) was established between the California Institute of Technology and the
Lawrence Berkeley National Laboratory in California27
JCAP draws on the expertise and capabilities of key
collaborators from the University of California (UCI and UCSD) and the SLAC National Accelerator Laboratory
operated by Stanford University The initial funds in 2010 amounted to $122 million JCAP is the largest
artificial photosynthesis network in the US with more than 190 persons linked to the programme The research
foci encompass electro-catalysis photo-catalysis and light capture materials integration and numerical
23
httpwwwmetigojpenglishpress20121128_02html 24
httpwwwk-caporkrenginfoindexhtmlsidx=1 25
httpwwwsogangackrnewsletternews2011_eng_1news12html 26
httpswwwicef-forumorgannual_2015speakersoctober8cs2appdfcs-2_20058_kyung_byung_yoonpdf 27
httpsolarfuelshuborgwho-we-areoverview
64
modelling test-bed prototyping and benchmarking The funds for the next five-year period (2016-2020)
amount to $75 million and are subject to congressional appropriation
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years Core members include the Northwestern University and
Uppsala University A process of exchanges is instituted which encompasses six different universities in four
countries Industry partners are ILampFS (India) Total (France) and Shell28
This list is not exhaustive and increasing interest in the field of artificial photosynthesis would certainly lead to
the launch of new national and international programmes
422 Main research groups (with link to network if any)
A list of the main research groups outside Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire AP
community outside of Europe We are confident however that it provides an accurate indication about the AP
sector outside of Europe
Table 43 Number of research groups and research institutions in non-European countries
Country Number of research groups Number of research institutions Average size of a
research group
Australia 1 1 18
Brazil 1 1 5
Canada 1 1 -
China 12 5 13
Israel 1 1 6
Japan 16 15 15
Korea 4 4 16
Singapore 1 1 14
US 40 32 18
Total 77 61 5
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 61 main research institutions or universities working on artificial photosynthesis outside of
Europe most of which are based in the US and in Japan Those research institutions contain 77 individual
research groups with an average group size of 8 people29
Yet the sizes of research groups can vary widely
from 26 members at the University of Tokyo to only two persons at Kobe University The country with both the
highest number of involved institutions and research groups is the US where 40 individual research groups in
32 research institutions are active Hence the US is a world leader in terms of research groups working on
AP Japan follows with 16 institutions and 15 research groups which lies below the numbers for Germany
and the Netherlands Almost 80 of the research groups (77) focus on the second pathway
(photoelectrocatalysis) whereas about 39 research the first pathway (synthetic biology amp hybrid
systems) The remaining 18 focus their activities on the third pathway (co-electrolysis) Table 44
28
httpwwwsolar-fuelsorgabout-sofi 29
The average group size is derived from survey responses For more information please refer to Annex I
65
provides an overview of some of the key statistics such as the number of AP research groups and institutions
per country and their respective focus on one of the three technology pathways
Table 44 Number of research groups per research area (technology pathway)
Country Technology
pathway
Total Synthetic biology
and hybrid systems
Photoelectrocatalysis Co-electrolysis
Australia 1 1 1 0
Brazil 1 0 1 0
Canada 1 0 1 1
China 12 4 6 2
Israel 1 1 0 1
Japan 16 7 15 1
Korea 4 0 4 0
Singapore 1 0 1 0
US 40 17 30 9
Total 77 30 59 14
Note a research group might focus on multiple technology pathways
Source Ecorys
In the following section our findings are illustrated by presenting some of the main research institutions and
their research groups
China ndash Dalian University of Technology
In 2011 the Dalian National Laboratory for Clean Energy (DNL) based at the Dalian Institute of Chemical Physics
(DICP) of the Chinese Academy of Sciences (CAS) was established It integrates research into clean energy and the
efficient use of fossil fuels to meet Chinas sustainable energy development strategy It is led by Li Can
Israel - Weizmann Institute of Science
To meet the challenge of providing clean sustainable energy the Weizmann Institute has established the Alternative
Sustainable Energy Initiative (AERI) The goal of this initiative is to create the conditions conducive to alternative
energy research and to identify promising avenues of research With the help of AERI the Weizmann institute hopes to
encourage its scientists to conduct basic research relevant to the future development of alternative sustainable energy
and to nourish the next generation of scientists in this field around the world in Israel and at the Weizmann Institute
The researchers at the Weizmann Institute of Science and at AERI preliminarily focus on the third pathway
Japan ndash University of Tokyo
The Domen Laboratory at the University of Tokyo is a research group focused on the second technological pathway
Their challenge is to find out novel photocatalysts that effectively work on water splitting under visible light by studying
different new materials
US ndash Arizona State University
The multidisciplinary team of the Center for Bio-inspired Solar Fuel Production of the Arizona State University aims to
design a complete system for solar water oxidation and hydrogen production Therefore they are focusing on five
specific subtasks (i) The total system analysis of the solar water-splitting device (ii) water oxidation (iii) fuel
production (iv) the artificial reaction center-antenna which relates to light collection and (v) the development of
functional nanostructured transparent electrode materials Their focus lies hence on the first and second AP technology
pathways
The density of research groups per country in the world is presented schematically in Figure 42 Please note
that in this figure (as opposed to Figure 41) we do not count each European country individually but
aggregate the numbers for all of Europe
66
Figure 42 Research groups active in the field of AP globally
Source Ecorys
43 Level of investment
In this section the level of investment is discussed in further detail The level of research investment in the EU
is based on the total budget of the projects whenever available In addition information is given on the time
period of the research projects
Information on the investment related to or funding of artificial photosynthesis research programmes and
projects at the national level is generally difficult to find especially for academic research groups Most budget
numbers found relate to the budget of the institution andor the (research) organisation in general and are not
linked to specific artificial photosynthesis programmes in particular unless the institute or research
programme is completely focused on artificial photosynthesis
Table 45 presents an overview of the investments made by a number of organisations
Table 45 Investments in the field of artificial photosynthesis
Country Organisation Budget size Period
Research investments in Europe
EU European Commission (FP7 and previous
funding programmes) euro 30 million 2005 - 2020
France CEA euro 43 billion 2014 covers not only AP
Germany
German Aerospace Centre (DLR) and the
Helmholtz Zentrum euro 4 billion
Annual budget covers
not only AP
Germany
Max Planck Institute for Chemical Energy
Conversion euro 17 billion 2015 covers not only AP
Germany
BMBF ldquoThe Next Generation of
Biotechnological Processesrdquo euro 42 million 2010 - present
Germany Government of Bavaria euro 50 million
2012-2016 covers not
only AP
Members of AMPEA AMPEA (EERA) euro 60 million 2010 - present
Netherlands Biosolar Cells euro 42 million 2010-present
Sweden Consortium for Artificial Photosynthesis euro 118 million 2013
UK SolarCAP and other initiatives in UK euro 92 million 2008-2013
67
Country Organisation Budget size Period
UK
University of East Anglia Cambridge and
Leeds euro 1 million 2013
Research investments outside Europe
China Dalian National Laboratory for Clean Energy euro 40 million Annual budget since
2011
Israel AERI euro 13 million 2014-2017
Japan ARPChem euro 122 million 2012 - 2021
Korea KCAP euro 385 million 2009 - 2019
UK US Plug-and-play photosynthesis euro 44 million 2014 - 2017
US JCAP euro 175 million 2010 - 2020
US SOFI euro 1 billion 2012 - 2022
Source Ecorys
431 Research investments in Europe
In Europe national researchers research groups and consortia are generally funded by European funds (such
as the ERC Grant from the European Commission) national governments businesses and universities In this
section special attention is paid to the EU FP7 projects These projects are mainly funded by European
contributions Further information is provided on AMPEA BioSolar Cells CAP SolarCap and some other AP
initiatives
Investments range between euro10 million for the national consortia (UK - SolarCap and Sweden - CAP) and euro42
million for the Dutch consortium to smaller budgets for local projects The projects at the European level are
more extensive The funds for all twenty FP7 projects related to artificial photosynthesis amount to a total
value of euro30 million AMPEA consists of around 400 professionals and an investment of approximately euro60
million contributed by the participants and associates themselves
Funding of AP research programmes and research consortia
EU ndash FP6 and FP7 projects
The FP6 and FP7 projects (6th
and 7th Framework Programmes for Research and Technological
Development) were undertaken in seven years between 2002 and 2013 and had a total budget of over euro60
billion30
Within FP7 around two thirds of the overall budget was aimed for the Cooperation programme of
which energy is one of the ten key thematic areas Investment in energy research under EU FP7 has been
around euro25 billion Various projects on artificial photosynthesis solar-powered hydrogen production by means
of water splitting have been completed under the EUrsquos Seventh Framework Programme Projects include
inter alia Solhydromics Solar-H Directfuel and H20Split FP7 is the key tool to respond to Europersquos needs in
terms of jobs and competitiveness and to maintain leadership in the global knowledge economy31
The
successor programme of FP7 has a number of projects in the field of artificial photosynthesis For example
PECDEMO project32
aims to develop a hybrid photoelectrochemical-photovoltaic tandem device with a solar-
to-hydrogen efficiency of 8-10 This illustrates the trend to move from fundamental research of materials and
processes (that was the main focus in FP6 and FP7 programmes) to the development of prototypes to reach
higher TRL levels (that is the main focus in H2020 programme)
An overview of the EU FP6 and FP7 projects on AP is presented in the table below
30
httpseceuropaeuresearchfp6pdffp6-in-brief_enpdf httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 31
httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 32
httppecdemoepflchpage-113311-enhtml
68
Table 46 EU FP6 and FP7 projects on artificial photosynthesis
EU FP7 project Technology pathway Total budget EU contribution to
the total budget
Time
period
(months)
ARTIPHYCTION Photolectrocatalysis (Water Splitting ) euro 3594581 euro 2187040 36
DIRECTFUEL Synthetic Biology amp Hybrid Systems euro 4977781 euro 3729519 48
CO2PHOTORED Photolectrocatalysis (Water Splitting ) euro 176053 euro 176053 24
COFLeaf Photolectrocatalysis (Water Splitting ) euro 1497125 euro 1497125 60
EWOCS Photolectrocatalysis (Water Splitting ) euro 168896 euro 168896 24
FAST MOLECULAR
WOCS
Photolectrocatalysis (Water Splitting )
euro 100000 euro 100000 48
H2OSPLIT Photolectrocatalysis (Water Splitting ) euro 100000 euro 100000 48
HJSC Research for fundamental understanding euro 337094 euro 337094 36
NANO-PHOTO-
CHROME
Synthetic Biology amp Hybrid Systems euro 218731
euro 218731 17
HyMap Photolectrocatalysis (Water Splitting ) euro 2506738 euro 2506738 60
PCAP Photolectrocatalysis (Water Splitting ) euro 190800 euro 190800 36
PHOTOCATH2ODE Photolectrocatalysis (Water Splitting ) euro 1500000 euro 1500000 60
PHOTOCO2 Photolectrocatalysis (Water Splitting ) euro 50000 euro 50000 24
PS3 Synthetic Biology amp Hybrid Systems euro 1997944 euro 1997944 60
SOLAR-H Synthetic Biology amp Hybrid Systems euro 2316000 euro 1800000 36
SOLAR-JET Photolectrocatalysis (Water Splitting ) euro 3123950 euro 2173548 48
SOLHYDROMICS Synthetic Biology amp Hybrid Systems euro 3655828 euro 2779679 42
SUSNANO Catalysts can be either used for hybrid
systems or the water splitting category euro 100000
euro 10000 54
TRIPLESOLAR Photolectrocatalysis (Water Splitting ) euro 2493585 euro 2493585 60
light2hydrogen Photolectrocatalysis (Water Splitting ) euro 900000
Total euro 30005106 euro 24016752 821
Source FP7 Project list
In total euro30 million of which 80 were based on European contributions have been spent on 20 projects
related to artificial photosynthesis Most projects were completely funded by the European Union On average
the time period of these projects was around 43 months the shortest project lasting only 17 months and the
longest one 60 months Almost all funding related to the topics of photoelectrocatalysis (55) and synthetic
biology amp hybrid systems (44) Some additional funding was spent on research for fundamental
understanding (the HJSC project) and catalysts which are useful for either hybrid systems or water splitting
(the SUSNANO project)
Table 47 Total EU budget on artificial photosynthesis per technology pathway
Technology pathway TRL Total budget
Synthetic biology amp hybrid systems 1-2 euro 13166284
Photoelectrocatalysis (water splitting ) 1-4 euro 16401728
Catalysts that can be used for both categories above 1-4 euro 100000
Research for fundamental understanding - euro 337094
Total - euro 30005106
69
Based on the monthly funding of the FP7 projects33
it may be observed that annual investments in artificial
photosynthesis have been increasing over the years (Figure 43) There were no projects on artificial
photosynthesis in 2008 therefore no investments were made The highest investment was made in 2014 with
euro45 million spent on projects After that investments have been decreasing It is however expected that
from 2016 more projects on artificial photosynthesis will be conducted therefore investment will rise
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020
Note It is assumed that the funding of the projects is evenly distributed over months Thus annual expenditures are
calculated as a sum of the monthly expenditures Project lsquolight2hydrogenrsquo is excluded from the calculation since there is no
information available on the number of months the project is running
Source Ecorys
EU ndash AMPEA (EERA)
EERA is an alliance of leading organisations in the field of energy research comprising more than 150
participating organisations all over Europe The primary focus of EERA is to accelerate the development of
energy technologies to the point that they can be embedded in industry-driven research Activities of EERA
are based on the alignment of own resources while over time the Joint Programmes can be expanded with
additional sources including from Community programmes34
In EERA approximately 3000 FTE (equivalent
of 3000 professionals) are involved which makes for a budget of around euro450 million35
AMPEA is one of the
programmes under EERA focusing on AP in which roughly 400 professionals are involved This would then
make for an investment of approximately euro60 million for AMPEA
The Netherlands ndash BioSolar Cells
The total budget of BioSolar Cells is around euro42 million based on public and private funds The Ministry
contributed euro25 million the NWO (The Dutch organisation on Scientific Research) euro35 million and Dutch
universities and research centres around euro7 million Private organisations invested euro65 million The specific
research programme Towards Biosolar Cells in which the Delft University of Technology is involved is
being allocated a budget of euro25 million by the Dutch Ministry of Agriculture Nature and Food Quality A
benefit of funding partly by private funding is the focus on building infrastructure and retaining key
33
It is assumed that funding is spread evenly over the months that the project is being implemented This means that if a project is running 36 months with a total budget of euro1 million it is assumed that monthly investments are euro83000 (1 million 12) If a project started in May 2010 then investment over the whole year 2010 is calculated as 8euro83000 After annual investment is calculated for all projects yearly total investment is calculated as a sum across projects
34 httpssetiseceuropaeuimplementationtechnology-roadmapeuropean-energy-research-alliance-eera
35 httpwwwapreitmedia168877busuoli_eneapdf
70
researchers Public funding of artificial photosynthesis is mostly for the short term facilitating the entry of new
groups36
Swedish ndash CAP
The Swedish Consortium for Artificial Photosynthesis connecting the universities of Lund Stockholm and
Uppsala is chaired by Stenbjoumlrn Styring There are 80 persons linked to the consortium In 2013 the Swedish
Energy Agency distributed the amount of euro118 million (SEK 108 million) in total to lsquosome of Swedenrsquos best
research groupsrsquo Out of this amount euro87 million went to three research groups at Uppsala University euro37
million to research on artificial photosynthesis to generate solar fuels euro32 million for research on dye-
sensitised solar cells and euro18 million to research on thin film solar cells (TFSC) It is the largest one-time
investment in solar energy ever in Sweden37
The Swedish Consortium for Artificial Photosynthesis ndash Stenbjoumlrn Styring
The project Molecular Solar Energy Sciences is funded by the KampA Wallenberg Foundation with euro5 million The main
research activities related to artificial photosynthesis include mechanistic studies on synthetic molecular and
moleculesemiconductor systems for the light-driven reduction of protons and CO2 and oxidation of water Furthermore
research is conducted on cyanobacteria systems for photo-biological fuel generation synthetic biology molecular
biology and metabolic engineering A second project on artificial photosynthesis is funded by the Swedish Energy
Agency (euro4 million) An additional four projects are funded by Swedish and European sources with a total of euro5
million38
UK ndash SolarCAP and others
The Engineering and Physical Sciences Research Council (EPSRC) in the UK supports several AP-related
projects through the Towards a Sustainable Energy Economy programme39
The total amount of funding is
approximately euro92 million
New and Renewable Solar Routes to Hydrogen is led by Imperial College London and is targeting both
artificial and natural photosynthetic routes to solar-derived hydrogen (euro5 million)40
Artificial Photosynthesis Solar Fuels is led by the University of Glasgow (euro2 million)41
The SolarCAP consortium for Artificial Photosynthesis is a consortium of five UK academic research
groups (based at the Universities of East Anglia Manchester Nottingham and York) they are working to
develop solar nanocells for the production of carbon-based solar fuels (euro22 million)
Funding of other AP initiativesprojects
Germany ndash German Aerospace Centre (DLR) and the Helmholtz Zentrum
The Helmholtz Zentrum is Germanyrsquos largest scientific organisation with more than 38000 employees and an
annual budget of more than euro4 billion42
It consists of 18 scientific technical biological and medical research
centres The research institutes of the German Aerospace Centre (DLR) are affiliated with the Helmholtz
Zentrum One of the Institutes of DLR the Institute of Solar Research forms part of the Helmholtz Zentrum
programme for renewable energies This programme focuses on projects on cost reduction in solar thermal
power plants the thermo-chemical generation of solar fuels in the period 2015-2019 the solar tower in Juumllich
the bioliq pilot plant and the Gross Schoumlnebeck geothermal research platform43
Research institutes submit
their research projects for evaluation by an international panel in order to qualify for funding under the
Renewable Energies Programme based on the outcome the Helmholtz Zentrum makes funding
recommendations for a five-year period
36
httpbiomassmagazinecomarticles2883towards-biosolar-cells-program-receives-government-funding 37
httpwwwuuseennewsnews-documentid=2282amptyp=artikelamparea=2amplang=en 38
Information is based on the survey responds 39
httpwwwrscorgglobalassets04-campaigning-outreachrealising-potential-of-scientistsresearch-policyglobal-challengessolar-fuels-2012pdf
40 httpgowepsrcacukNGBOViewGrantaspxGrantRef=EPF00270X1
41 httpgtrrcukacukprojectsref=EPF0478511
42 httpwwwdlrdesfendesktopdefaultaspxtabid-888515347_read-37692
43 httpwwwhelmholtzdeno_cacheenresearchenergyrenewable_energies
71
Germany ndash The Max Planck Institute for Chemical Energy Conversion (MPI CEC)
The MPI CEC was founded in 2012 to focus on the issue of energy conversion Its researchers analyse the
basic processes of energy storage and conversion within three research departments which encompass 200
employees44
The MPI CEC is for the most part financed by public funds from both the German state and
regions The MPI CEC is part of the Max Planck Society for the Advancement of Science which is a formally
independent non-governmental and non-profit association of German research institutes The budget of the
entire society amounted to euro17 billion in 2015
Germany ndash Federal Ministry of Education and Research (BMBF)
In 2010 the BMBF launched the initiative ldquoThe Next Generation of Biotechnological Processesrdquo45
Part of this
initiative were deliberations directed toward simulating biological processes for material and energy
transformation A funding amounting euro42 million is available for the first 35 projects on microbial fuel cells
artificial photosynthesis and universal production46
Germany ndash SolTech (Solar Technologies Go Hybrid)
The Government of Bavaria initiated SolTech an interdisciplinary project to explore innovative concepts for
converting solar energy into electricity and non-fossil fuels The project brings together research by chemists
and physicists at five different Bavarian Universities and is funded with euro50 million for the period 2012-201647
The SolTech network covers all fields of research on solar energy use such as the conversion of solar energy
to electricity for immediate use and the conversion of solar energy into chemical energy for storage and future
use
France - Alternative Energies and Atomic Energy Commission (CEA)48
CEA is a public government-funded research organisation active in four main areas low-carbon energies
defence and security information technologies and health technologies The CEA is the French Alternative
Energies and Atomic Energy Commission The CEA had a total budget of euro43 billion and around 16000
permanent staff On photovoltaic cell technology CEA is collaborating with Photowatt Pechiney and Appolon
Solar and on photovoltaic modules and systems with TOTAL Energie
UK - University of East Anglia (UEA) Cambridge and Leeds
A specific research programme by the UEA on the creation of hydrogen with energy derived from
photocatalysts designed to replicate photosynthesis is funded by the Biotechnology amp Biological Sciences
Research Council (BBSRC) The total amount of funding is approximately euro1 million (pound800000)49
432 Research investments outside Europe
The main research programmes and consortia discussed are JCAP (US) SOFI (US) ARPChem (Japan)
AnApple (Japan) and KCAP (Korea) In contrast to Europe the use of energy innovation hubs ie major
integrated research centres drawing together researchers from multiple institutions and varied technical
backgrounds is more common in the US and Asia Also partnerships between the government academia
and industry seem to be more common in those areas than they are in Europe The idea of developing new
energy technologies in innovation hubs is very different compared to the approach of helping companies scale
up manufacturing through grants or loan guarantees50
The information on the budgets from the large
networks is generally available
44
httpwwwcecmpgdeinstitutdaten-faktenhtml 45
httpswwwbiotechnologiedeBIONavigationENrootdid=164934htmlview=renderPrint 46
httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf 47
httpwwwsoltech-go-hybriddeabout-soltech 48
httpenglishceafrenglish-portal 49
httpwwwwiredcouknewsarchive2013-0122artificial-photosynthesis 50
httpswwwtechnologyreviewcoms429681artificial-photosynthesis-effort-takes-root
72
Funding of AP research programmes and research consortia
Japan ndash ARPChem
In Japan the Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology (MEXT) launched a large artificial photosynthesis project that will tackle the study for
the coming decade between 2012 and 2021 with an expected budget of about euro122 million (15 billion yen)
The main organisation to conduct the project is the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem)51
Japan ndash AnApple
All Nippon Artificial photosynthesis Project for Living Earth (AnApple) is a five-year research programme
(2012-2017) joined by more than 40 Japanese leading scientific groups In this strong collaboration they aim
at achieving breakthroughs for the realisation of artificial photosynthesis AnApple hosted The International
Conference on Artificial Photosynthesis (ICARP)rdquo in 2014 and receives strong financial support52
from the
Ministry of Education Culture Sports Science and Technology
Korea ndash KCAP
The Korea Center for Artificial Photosynthesis (KCAP) at Sogang University was established in September
2009 through complementary and collaborative research with the Lawrence Berkeley National Lab (LBNL) in
the US to build the foundation for the realisation and commercialisation of artificial photosynthesis KCAP
receives a grant of euro385 million (50 billion won in 10 years) from the Ministry of Education Science and
Technology (MEST) through the National Research Foundation of Korea (NRF)
US - JCAP
JCAP (Joint Centre for Artificial Photosynthesis) was established in 2010 by the Department of Energy as one
of the Energy Innovation Hubs with a fund of euro108 million ($122 million) for five years Additional funding for
the next five years amounts to euro67 million ($75M) but is still subject to congressional appropriation53
JCAP
is the largest artificial photosynthesis research programme in the world There are 190 persons linked to the
research programme
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years SOFI (Solar Fuels Institute) is focused on light capture
water splitting CO2 catalysis and photoelectrochemical cells SOFI relies on a community of member
institutions and individual supporters who believe strongly in a clean energy future54
The solar fuel created
using catalysts and technology shared by global members of SOFI is funded by crowdfunding campaigns
(Kickstarter campaign) Furthermore SOFI partnered with TSRC to raise by means of a bold campaign one
billion dollars over the next ten years to fund the research55
Funding of other AP initiativesprojects
US ndash Plug-and-play photosynthesis CAPP (combining algal and plant photosynthesis)
Three UKUS-funded projects received funding to improve photosynthesis The three research teams (each
comprised of scientists from the United Kingdom and the United States) have been awarded a second round
of funding to build on their research findings and develop new ways to improve photosynthesis Projects
include plug-and-play photosynthesis by the Arizona State University Multi-level Approaches for Generating
Carbon Dioxide (MAGIC) led by the Pennsylvania State University and Combining Algal and Plant
Photosynthesis (CAPP) led by the Stanford University received in 2014 a new round of funding of euro44 million
51
httpwwwmetigojpenglishpress20121128_02html 52
httpartificial-photosynthesisnetICARP2014scopehtml The concrete funding figures are not available 53
httpenergygovarticlesenergy-department-provide-75-million-fuels-sunlight-hub) httpsolarfuelshuborgresearchoverview 54
httpwwwsolar-fuelsorgdonate 55
httpstelluridescienceorgsofi-brochurepdf
73
(pound5 million) in total over three years from the Biotechnology and Biological Sciences Research Council
(BBSRC) and the National Science Foundation56
Israel ndash Projects funded by AERI
AERI is providing a pool of funds to try out new ideas and jump-start research projects that are not applicable
for conventional grants Since 2006 already 8 cycles of AERI-funded projects took place Projects under the
20132014 cycle include lsquoNew Options for Solar Energy Conversion to Biofuel and Electricity ndash Biofuels ndash
Photovoltaics and Opticsrsquo57
Funding is provided by the Canadian Center for Alternative Energy Research the
Helmsley Energy Program the Helmsley Charitable Trust (providing euro13 million ($15 million) over three
years) the Burk Fund for Alterative Energy Studies the Eisenberg Foundation and individuals58
China ndash Funding of the Dalian National Laboratory for Clean Energy
The Dalian National Laboratory for Clean Energy was established in 2011 The investments into this lab
amount to more than euro40 million (289 million RMB) a year (over 50 of annual research of the Dalian
University of Technology within which the laboratory functions)59
In addition to this laboratory Haldor Topsoe
opened an RampD Center60
at the same university to join forces in the research of clean energy Haldor Topsoe
is also going to sponsor RampD projects however the size of the investments is not revealed Prior to that
Topsoe already established a scholarship with a value of around euro400 a month (3000 RMB)61
44 Strengths and weaknesses
This section presents the analysis of the strengths and weaknesses of the research community in the field of
artificial photosynthesis The findings are based on the results of the survey conducted during March 2016
and are supplemented by desk research Firstly we outline the main strengths and weaknesses with regard to
global AP research Secondly the strengths and weaknesses of the European community compared to the
non-European community are presented
441 Strengths and weaknesses of AP research in general
Table 48 below summarises the strengths and weaknesses of research in AP taking a global perspective
Table 48 Summary of strengths and weaknesses of research globally
Strengths Weaknesses
A diverse community of researchers bringing together
experts in chemistry photochemistry electrochemistry
physics biology catalysis etc
Researchers focus on all technology pathways in AP
Existing research programmes and roadmaps in AP
Available financial investments in several countries
Limited communication cooperation and collaboration
at an international level
Limited collaboration between academia and industry
at an international level
Transfer from research to practical applications is
challenging
Note International level refers not only to EU countries but all around the world
Globally there is a wide variety of RampD institutes (and researchers) focused on AP forming a diverse
community of researchers Research in AP requires interdisciplinary teams The experts working together
on this topic often have backgrounds in chemistry physics and biology
56
httpwwwbbsrcacuknewsfood-security2014140602-pr-bbsrc-and-nsf-funding-photosynthesis 57
httpwwwweizmannacilAERIresearch 58
httpwwwweizmannacilresdevsitesweizmannacilresdevfilesenergy_booklet_lo_res_2012pdf 59
httpwwwnaturecomnews2011111031fullnews2011622html 60
httpwwwtopsoecomnews201602topsoe-establishes-rd-center-dalian-institute-chemical-physics-china 61
httpwwwdnlorgcnshow_enphpid=776
74
A diverse community of researchers is focusing on all the pathways in AP which ensures diverse
approaches an exchange of different views a dynamic research community and avoids lock-ins into one
specific pathway This broad and inclusive research approach is the best way to maximise the probability of
AP research being successful in developing efficient and commercially viable AP processes
Several countries have dedicated programmes andor roadmaps to the topic of AP The US Japan the
Netherlands and South Korea have invested in large-scale interdisciplinary research programmes (specifically
on solar fuels) China and Japan have dedicated centres for renewable energy research where solar fuels are
an area of substantial effort For example the Department of Energy of the US sponsors Energy Innovation
Hubs aiming to overcome scientific barriers to develop a complete energy system with the potential to turn into
a transformative energy technology62
One of such innovation hubs is the Joint Center for Artificial
Photosynthesis established in 2010 In the Netherlands a public private partnership was established to form
BioSolar Cells of which one of the main focal themes is AP Globally several hundreds of millions of euros
are being spent this decade on AP research and this research seems to be intensified further
Despite the intensification of global research efforts the communication cooperation and collaboration at
an international level remains limited Many AP consortia link different research groups but operate only at
a national level63
Yet a higher level of institutionalised international or global cooperation going beyond
international academic conferences could spur innovative research in the field and enhance knowledge
exchange and spill-overs A number of survey respondents indicated that the lack of coordination
communication and cooperation at an international level is one of the main weaknesses in current AP-related
research activities
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research
including research on artificial photosynthesis In Japan the industry is involved in AP research to a greater
degree64
Nevertheless although companies are participating in local consortia such as ARPChem and
BioSolar Cells there seems to be a lack of cooperation between academia and industry at an
international level
The transfer of research to industrial application in artificial photosynthesis remains challenging In order
to attract the attention of the private sector artificial photosynthetic systems must be cost-effective efficient
and durable An active involvement of industrial parties could help bringing research prototypes to
commercialisation This step towards commercialisation requires a sufficient critical mass and funding
however which cannot be borne by a single country
442 Strengths and weaknesses of AP research in Europe
Table 49 below summarises the strengths and weaknesses of research in artificial photosynthesis in Europe
as compared to non-European research
62
httpscienceenergygovbesresearchdoe-energy-innovation-hubs 63
The only exception is AMPEA with its pan-European reach 64
The Korean Centre for Artificial Photosynthesis (KCAP) collaborates with a number of companies Toshiba and Panasonic made some advances in artificial photosynthesis research (httpasianikkeicomTech-ScienceScienceHow-artificial-photosynthesis-could-cut-emissions) ARPChem has a few corporate members on board (httpwwwmetigojpenglishpress2012pdf1128_02bpdf)
75
Table 49 Summary of strengths and weaknesses of research in Europe
Strengths Weaknesses
A strong diverse community of researchers
RampD institutions research capacity and facilities
Existing research programmes and roadmaps for AP in
several MS
Available financial investments in MS
Ongoing and conducted FP7 projects at EU level
Close collaboration of research groups in consortia
Limited communication cooperation and collaboration at
a pan-European level
Limited collaboration between academia and industry
within Europe
Limited funding mostly provided for short-term projects
focusing on short-run returns
National RampD efforts in AP are scattered
Europe has a diverse research community working on artificial photosynthesis research covering all the
technology pathways Europersquos universities have many highly educated researchers in the fields of chemistry
physics and biology at their disposal There is a solid foundation of RampD institutions research capacity
and facilities such as specialised laboratories which work together at a national level
National research programmes and roadmaps for AP exist in several Member States an indication that
AP research is on the agenda of European governments65
Therefore also financial investment for AP
research is available in several MS such as in Germany66
and other countries European-level
collaboration between different research groups and institutes from different countries has been achieved in
the framework of FP7 projects67
as well as predecessors of it
Five main consortia in Europe ensure that research groups and research institutes are collaborating
closely68
such as in Sweden where the Consortium for Artificial Photosynthesis (CAP) is active and in the
Netherlands where researchers work in close cooperation within the BioSolar Cells consortium Nevertheless
there is still much room to expand globally as well as within Europe most consortia are operating within and
collaborating with research groups in countries where they are based themselves
The level of cooperation and collaboration at a pan-European level hence seems to be limited There
are a few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7 projects
but many research groups are operating locally and are funded by national governments Several survey
respondents reported a low degree of collaboration among different research groups which typically results in
a duplication of efforts and a lack of generalised standards Synergies which could potentially boost research
in artificial photosynthesis are being overlooked Creating for example a communication platform to facilitate
the exchange among researchers could more easily promote the development of knowledge and increase the
speed of discovery and exploitation of new robust (effective and durable) photocatalysts innovative processes
and devices etc Moreover another indicated weakness is the lack of collaboration between already existing
and ongoing projects
While industrial companies are present in a few consortia there is limited collaboration between European
academia and industry Improved collaboration could result in the development of more advanced AP
processes and AP process devices and it might improve the probability of APrsquos successful commercialisation
in the foreseeable future
65
For example Strategic Energy Technology (SET) Plan European Biofuels Technology Platform (EBTP) and European Industrial Bioenergy Initiative (EIBI) JCAP scientific programme For more information please refer to Deliverable 1 Chapter 32
66 By now research funded by the government of Germany in the field of artificial photosynthesis amounts to euro 42 million (httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf)
67 See Deliverable 1
68 httpswwwleopoldinaorgenpolicy-adviceworking-groupsartificial-photosynthesis
76
The long-term focus of AP research is a hurdle for both gaining cooperation with industry and for obtaining
funding Compared to that of its non-European counterparts European funding focuses on the short
term69
While in the USA and Japan funding is dedicated for about 5-10 years European parties often get
funding for about 4 years at the most Although several MS also have dedicated RampD programmes focusing
on AP the amounts provided by non-European counterparts exceed those of the European70
Furthermore
these national programmes are fragmented ie lacking a common goal and perspective hence the funding
of research is also fragmented and scattered71
The European community of researchers could benefit
from an integrated programme which clearly indicates research goals and objectives In addition a common
funding scheme set up to support fundamental research in artificial photosynthesis and to promote
collaboration with industry could advance the research in artificial photosynthesis
A number of survey respondents indicated that there is currently little focus of EU-funded research on
technologies with low TRL within H2020 At the moment there is a strong emphasis on the projects and
technologies which already have a rather high TRL expecting returns in the near future while research in the
area of low TRL technologies requires some attention and funding Several respondents mentioned that there
exist still quite some barriers regarding the design of low-cost materials with low TRL and with higher stability
and activity (eg performance of devices when it comes to a discontinuous supply of energy)72
45 Main industrial actors active in AP field
451 Industrial context
The idea behind artificial photosynthesis is that solar fuels could solve worldwide energy problems by using
water and carbon dioxide and converting them into the fuels we need Artificial photosynthesis can convert
sunlight directly into chemical fuels which makes it possible to harvest and store energy However there are
still many obstacles to make this technology commercially viable Only if artificial photosynthesis can be
provided efficiently stably safely and cheaply will it be beneficial for the public This means inter alia that an
efficient light absorber and catalysts need to be created to convert sunlight into fuel Even though there are
rapid developments in the field of artificial photosynthesis there are many obstacles to overcome in order to
reach mass production Currently the positioning of the fields of artificial photosynthesis and solar fuels is at
around a 3 on the technology readiness level
452 Main industrial companies involved in AP
At the moment the number of companies active in the field of AP is limited Based on our analysis of the main
AP actors in the industry only several tens of companies appear to be active in this field Moreover industrial
activity is limited to research and prototyping as viable AP technologies have not (yet) been commercialised
35 companies active in the field of AP have been identified comprising 16 European companies and 19 non-
European companies (Table 410) Seven of these are in Germany eight in the Netherlands eight in Japan
and 10 in the US The following table summarises the countries in relation to one or more of the technology
pathways
69
Already in 2013 it was indicated that much of public funding of basic AP research remains short term For more information see Thomas FaunceStenbjorn Styring Michael R Wasielewski Gary W Brudvig A William Rutherford et al (2013) Artificial Photosynthesis as a Frontier Technology for Energy Sustainability Energy amp Environmental Science Issue 4 2013
70 A number of respondents indicated that the available funding is not sufficient to finance research facilities and equipment
71 This weakness is indicated by several respondents
72 This is also mentioned as one of the areas of attention in Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press)
77
Table 410 Overview of the size of the industrial community number of companies per pathway
Country Synthetic biology amp
hybrid systems
Photoelectrocatalysis Co- electrolysis Total number of
companies
European companies
France 1 1 0 1
Germany 2 2 0 4
Italy 0 1 0 1
Netherlands 3 4 1 8
Switzerland 0 1 0 1
Total 6 9 1 15
Non-European companies
Japan 0 8 0 8
Saudi Arabia 0 1 0 1
Singapore 0 0 1 1
US 3 2 4 8
Total 3 11 5 19
Note a company can be active in multiple technology pathways
Source Ecorys
With respect to the industry largely the same countries stand out as in the research field namely Japan the
US and north-western Europe The industry in Japan appears to have the most intensive research activities
in AP as several large Japanese multinationals have set up their own AP RampD laboratoriesresearch
departments
With respect to the three technology pathways (i) synthetic biology amp hybrid systems (ii) photoelectrocatalysis
and (iii) co-electrolysis we have observed that most industrial (research) activity is being performed
concerning photoelectrocatalysis (19 companies) although there are also companies active in the two other
pathways
We have also identified a number of companies active in the area of carbon capture and utilisation that might
potentially be involved in the research of artificial photosynthesis
453 Companies active in synthetic biology amp hybrid systems
The pathway involving synthetic biology amp hybrid systems is still at an early stage on the TRL scale (TRL 1-2)
The challenges industries face relate mostly to efficiency obstacles Enzymes and proteins need to be
modified by genetic engineering Another barrier relates to the fact that the modifications and protein
production are still very time-consuming in terms of cell growthprotein purification Furthermore it is
necessary to improve protein stability and solubility by rational design directed evolution and modifying
sample conditions since currently proteins are unstable It would probably take about 10-20 years until
technologies reach TRL 7
The companies involved in this pathway range from chemical and oil-refining companies companies working
on bacteria companies producing organic innovative catalysts to others The following table lists the
organisations identified within this pathway
78
Table 411 Organisations in synthetic biology amp hybrid systems
Country Organisation (in EN)
France PhotoFuel
Germany Evonik Industries AG
Germany Brain AG
Italy Hysytech
Netherlands Biomethanol Chemie Nederland BV
Netherlands Photanol BV
Netherlands Tendris Solutions
Netherlands Everest Coatings
US Joule Unlimited
US Phytonix
US Algenol
Source Ecorys
Chemical and oil-refining companies
Biomethanol Chemie Nederland BV a Dutch company that produces and sells industrial quantities of high
quality bio-methanol focusing on synthetic biology amp hybrid systems is also a partner of the BioSolar Cells
programme The BioSolar Cells programme focuses its research on artificial photosynthesis photosynthesis in
cellular systems and photosynthesis in plants
Companies working on bacteria
Another group of companies in the pathway of synthetic biology amp hybrid systems focus on CO2 to fuel
processes that use cyanobacteria to convert CO2 into targeted fuels or chemicals (biological conversion)
Examples of such companies are Joule Unlimited Phytonix and Algenol all based in the US Algenol is
commercialising its patented algae technology platform for the production of ethanol using proprietary algae
sunlight carbon dioxide and saltwater The Dutch company Photanol uses cyanobacteria to turn CO2 into
certain predetermined products
Companies producing organic innovative catalysts
Many of the smaller companies currently active in developing AP originate from a specific research group or
research institute and focus on specific AP process steps andor process components Some companies
focus on the further development of both chemical and organic innovative catalysts which are earth-abundant
non-toxic and inexpensive Brain AG (Germany) is an example of such a company
Other companies
Hysytech is an Italian company experienced in technology development and process engineering applied to
the design and construction of plants and equipment for fuel chemical processing energy generation and
photoelectrocatalysis Hysytech is involved in an FP7 project to develop a fully artificial photoelectrochemical
device for low temperature hydrogen production
Other companies in the field of synthetic biology amp hybrid systems are Tendris Solutions (Netherlands) and
Everest Coatings (Netherlands) involved in the EET-Kiem project which focused on increasing the
absorption of visible light in the TiO2 photocatalyst by incorporating other elements in the structure and to
construct a photoelectrochemical reactor Photofuel in France and Phytonic in the US focus on synthetic
biology amp hybrid systems and photoelectrocatalysis Evonik Industries AG invests in synthetic biology amp
hybrid systems as well as carbon capture technologies which convert waste CO2 into products and fuels
79
454 Companies active in photoelectrocatalysis
The pathway of photoelectrocatalysis is relatively low on the TRL scale as well (TRL 1-4)
Photoelectrocatalysis would make it possible to use photovoltaic cells that absorb photons to facilitate water
splitting Research on photoelectrocatalysis using photoelectrochemical cells in particular is still at a very early
stage
Technologies pertaining to the photoelectrocatalysis pathway are not yet commercially viable with the main
challenges relating to the design of devices that are efficient stable and durable Further potential obstacles to
be taken into account relate to the incorporation of these technologies with other technologies that can
generate fuel molecules other than hydrogen
Most companies are involved in this pathway ranging from automotive manufacturers and electronic
companies to chemical and oil-refining companies The following table lists the organisations identified within
this pathway
Table 412 Organisations in the field of photoelectrocatalysis
Country Organisation (in EN)
France PhotoFuel
Germany Bauhaus Luftfahrt eV (Bauhaus Luftfahrt Research)
Germany ETOGAS
Italy Hysytech
Japan Toyota (Toyota Central RampD Labs)
Japan Honda (Honda Research Institute - Fundamental Technology Research Center)
Japan Mitsui Chemicals
Japan Mitsubishi (Mitsubishi chemicals Setoyama Laboratory)
Japan Sumitomo Chemicals (Energy amp Functional Materials Research Laboratory)
Japan INPEX Corporation
Japan Toshiba (Corporate Research and Development Center)
Japan Panasonic (Corporate Research and Development Center)
Netherlands InCatT BV
Netherlands Shell (Shell Game Changer Programme)
Netherlands Hydron
Netherlands LioniX BV
Saudi Arabia Saudi Basic Industries Corporation
Switzerland SOLARONIX SA
US HyperSolar
Source Ecorys
Companies in the automotive sector
Several automotive manufacturers are active in the field of AP mostly relating to the field of
photoelectrocatalysis In 2012 Honda opened a hydrogen station in Saitama Japan that converts sunlight
into hydrogen that could be used to power fuel-cell electric vehicles The station is focusing on
photoelectrocatalysis and turning sunlight into hydrogen via a high-pressure water electrolysis system that
was developed by Honda itself Since then there seems to be little activity from Honda73
73
httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
80
Figure 44 Hondarsquos sunlight-to-hydrogen station
Source httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
Toyota succeeded (in 2011) to generate organic compounds via artificial photosynthesis without using any
external energy andor material sources The system is focused on producing formic acid (which could be
used as a raw material in industry) In February 2016 Toyota Central RampD Labs announced that they
achieved the worldrsquos highest energy conversion efficiency rate of 46 with artificial photosynthesis using
water and carbon dioxide as raw materials and sunlight as energy to produce useful materials Toyota is also
researching new chemical reactions to generate more valuable organic compounds as a final product such as
methanol Toyota is primarily focused on photoelectrocatalysis The companyrsquos 2020 goal is to complete basic
testing for the creation of primary CO2-absorbing materials (material or fuel)74
Electronic companies
In addition to car manufacturers also electronic companies are involved in photoelectrocatalysis In December
2014 Toshiba announced its focus on producing a catalyst made of gold The company indicated that they
found a way to modify gold at the atomic level using nanotechnology which allows carbon dioxide to change
into other compounds at a lower voltage (with a record of 15 energy efficiency rate)75
In September 2015 Toshiba made public that the company developed a prototype of a new highly efficient
molecular catalyst (consisting of an imidazolium salt) that converts carbon dioxide into ethylene glycol without
producing other and unwanted by-products Most artificial photosynthesis technologies use a two-electron
reduction conversion process producing carbon monoxide and formic acid Others can achieve direct multi-
electron reduction but tend to produce many by-products and their separation can be problematic Toshibas
new molecular catalyst converts carbon dioxide into ethylene glycol via multi-electron reduction The long-term
goal of Toshibarsquos research work is to develop a technology compatible with carbon dioxide capture systems
installed at facilities such as thermal power stations and factories utilising carbon dioxide to provide (storable)
energy To this end Toshiba focuses on photoelectrocatalysis and further improvement of the conversion
efficiency by increasing catalytic activity and aims at practical implementation in the 2020s76
Panasonics artificial photosynthesis system is also focused on photoelectrocatalysis in particular on highly
efficient CO2 conversion which can utilise direct sunlight or focused light In 2012 Panasonic found that a
nitride semiconductor has the capability to excite the electrons with enough high energy for the CO2 reduction
reaction to take place Nitride semiconductors have attracted attention for their potential applications in highly
74
httpwwwtytlabscom and httpswwwasiabiomassjpenglishtopics1603_01html 75
httpwwwjapantimescojpnews20150412nationalscience-healthlab-photosynthesis-begins-to-bloomVw1YZP5f3IV 76
httpswwwtoshibacojprdcrddetail_ee1509_01html
81
efficient optical and power devices for energy saving However its potential was revealed to extend beyond
solid devices more specifically it can be used as a photoelectrode for CO2 reduction By making a devised
structure through the thin film process for semiconductors the performance as a photoelectrode has greatly
improved77
In September 2014 Panasonic Corporation managed to achieve a conversion efficiency rate of
0378
and not long after that the company announced to having achieved the first formic acid generation
efficiency of approximately 10 as of November 201479
According to Panasonic the key to achieving an
efficient artificial photosynthetic system lies in improved photoelectrodes and oxidation-reduction electrodes
Chemical and oil-refining companies
The developments with respect to solar fuels are also being supported by several chemical and oil-refining
companies Artificial photosynthesis has been an academic field for many years However in the beginning of
2009 Mitsubishi Chemical Holdings reported to be undergoing its own artificial photosynthesis research by
using sunlight water and carbon dioxide to create the carbon building blocks from which resins plastics and
fibres can be synthesisedrdquo80
In 2014 Mitsubishi established the research organisation Setoyama Laboratory
The Laboratory focuses on the development of artificial photosynthesis for chemical processes which is the
synthesis of raw materials such as ethylene propylene butenes etc by means of solar hydrogen obtained by
catalytic water splitting under visible light and CO2 emitted at a plant site81
The laboratory is also participating
in the ldquoArtificial Photosynthetic Chemical Processrdquo project (denoted ldquoARPChemrdquo) granted by NEDO (New
Energy Development Organization) In this project the following three programmes are conducted through
collaboration with academia and industry
1 Design of a photo semiconductor catalyst for water splitting
2 A membrane separation system for H2 from gas mixtures composed of H2 and O2 and
3 A catalytic process for the synthesis of lower olefins from H2 and CO2
The Japanese chemical companies Sumitomo chemicals and Mitsui Chemicals focusing on carbon
capture and photoelectrocatalysis are also participating in the ARPChem programme Sumitomo has its
own Energy amp Functional Materials Research Laboratory and is conducting research and development in a
broad range of fields Mitsui created the Mitsui Chemicals Catalysis Science Award and the Mitsui Chemicals
Catalysis Science Award of Encouragement in order to award recognition to national and international
researchers that have made substantial contributions to the field of catalysis science In 2014 it was the fifth
time that Mitsui has given these awards
Royal Dutch Shell cooperated with Bauhaus Luftfahrt in the EU-funded Solar-Jet project (2011-2015) in the
area of photoelectrocatalysis aimed at demonstrating an innovative process technology using concentrated
sunlight to convert carbon dioxide and water into synthesis gas (syngas) The syngas a mixture of hydrogen
and carbon monoxide is ultimately converted into kerosene by means of the commercial Fischer-Tropsch
technology With the first ever production of synthesised ldquosolarrdquo jet fuel the SOLAR-JET project has
successfully demonstrated the entire production chain for renewable kerosene obtained directly from sunlight
water and carbon dioxide (CO2)82
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University (US)
SOFI leads a global consortium that brings together universities from Rutgers University in New Jersey to
Uppsala University in Sweden83
SOFI focuses on both the water-splitting process (production of hydrogen)
and the CO2 reduction process (the reduction of carbon dioxide to carbon monoxide which in combination
77
httpnewspanasoniccomglobalpressdata201207en120730-5en120730-5html 78
httpswwwasiabiomassjpenglishtopics1603_01html 79
httpwwwpanasoniccomglobalcorporatetechnology-designtechnologyphotosynthesishtml 80
httpwwwdigitalworldtokyocomindexphpdigital_tokyoarticlesmanmade_photosynthesis_looking_to_change_the_world 81
httpwwwmcrccojpenglishrdsetoyama_laboratoryhtml 82
httpwwwsolar-jetaeropagepostsartsunlight-to-jet-fuel-european-collaboration-solar-jet-for-the-first-time-demonstrates-the-entire-production-path-of-ldquosolarrdquo-kerosene-4php
83 httpappsnorthbynorthwesterncommagazine2015springsofi
82
with hydrogen can be processed into eg methanol or synthetic gasoline) Total is also a partner of the
BioSolar Cells programme
INPEX Corporation is a Japanese oil company established in February 1966 as North Sumatra Offshore
Petroleum Exploration Co In addition to Mitsubishi Chemicals Sumitomo Chemicals and Mitsui Chemicals
INPEX also participates in the ldquoJapan Technological Research Association of Artificial Photosynthetic
Chemical Processrdquo (ARPChem) programme and engages in RampD projects with the aim to produce chemical
products like plastics and hydrocarbon fuel from photochemical catalysis INPEX Corporation is focused on
photoelectrocatalysis
Other companies
Other companies include Etogas (Germany) which develops builds and selects Power-to-Gas plants and
products related to Power-to-Hydrogen Power-to-SNG and Hydrogen-to-SNG LnCatT BV (Netherlands)
Hydron (Netherlands) Saudi Basic Industries Corporation (Saudi Arabia) and Hyper Solar () all focus on
photoelectrocatalysis LioniX BV (Netherlands - photoelectrocatalysis) and Solaronix SA (Switzerland -
photoelectrocatalysis) are focused on the further development of photoelectrochemical cells Hysytech and
Photofuel are in addition to the first pathway also involved in the second
455 Companies active in co-electrolysis
Even though co-electrolysis is the pathway at the highest levels of technical readiness compared to the other
two pathways not many companies are involved in it There are three electrolyser types capable of producing
hydrogen gas eg alkaline electrolysis polymer electrolyte membrane electrolysis and solid oxide electrolysis
cells (SOECs) Multiple designs are commercialised although SOECs using Fischer-Tropsch synthesis are
not yet commercially viable The companies involved in this pathway are mainly from the US Industries
combine co-electrolysis and the field of carbon capture Fuel cell products are used in the automotive
telecom defenceaerospace and consumer product sectors
The following table summarises the organisations in the field of co-electrolysis
Table 413 Companies in co-electrolysis
Country Organisation (in EN)
Netherlands Shell (Shell Game Changer Programme)
Singapore Horizon Fuel Cell Technologies
US Catalytic Innovations
US Opus 12
US LanzaTech
US Proton onsite
Source Ecorys
Companies include Proton onsite (US ndash PEM electrolysis) which manufactures hydrogen nitrogen and zero
air generators in a safe reliable and cost-effective way Horizon Fuel Cell Technologies (Singapore)
focuses on commercially viable fuel cells starting by simple products which need smaller amounts of
hydrogen The technology platform of horizon fuel cell technology is focused on three main topics PEM fuel
cell systems hydrogen supply and hydrogen storage Catalytic Innovations (US) Opus 12 (US) Lanzatech
(US) and Shell (NL) are also involved in the second pathway
83
456 Companies active in carbon capture and utilisation
The technology in the carbon capture and storage pathway can capture up to 90 of the CO2 and allows for
the separation of carbon dioxide from gases produced in electricity generation and industrial processes by
means of combustion capture and oxyfuel combustion The most advanced technologies are at TRL 7 eg
carbon capture in a coal plant
The following table shows the organisations active in the field of carbon capture and utilisationre-use
Table 414 Organisations active in carbon capture and utilisation
Country Organisation (in EN)
Denmark Haldor Topsoe
Germany Evonik Industries AG
Germany Siemens (Siemens Corporate Technology CT)
Germany Sunfire GmbH
Germany Audi
Switzerland Climeworks
UK Econic (Econic Technologies)
Canada Carbon Engineering
Canada Quantiam
Canada Mantra Energy
Iceland Carbon Recycling International
Israel NewCO2Fuels
Japan Mitsui Chemicals
US Liquid light
US Catalytic Innovations
US Opus 12
US LanzaTech
US Global Thermostat
Source Ecorys
Twelve companies currently only focus on carbon capture and utilisation These companies are therefore
technically not considered to be companies involved in artificial photosynthesis However they can potentially
be involved in AP research in the future Such companies include automotive manufacturers as well as
electronics companies Five companies are involved in carbon capture and one of the pathways
Automotive manufacturers
Audi is working together with the American company Joule Unlimited in order to research and produce lsquoe-
ethanolrsquo Joule optimised a production process in which microorganisms are able to produce and excrete
either ethanol or alkanes from carbon dioxide (CO2) and sunlight Audi and Joule opened a joint
demonstration plant in September 2012 where e-ethanol is produced in transparent plastic tubes (see Figure
45)
84
Figure 45 Demonstration facility of Audi and Joule in Hobbs (New Mexico)
Source httpwwwbest-practicesfrost-multimedia-wirecomjoule2015
In January 2014 Audi e-ethanol underwent its first-ever test cycle in the pressure chamber and glass engine
showing that fewer pollutants are produced in the combustion of e-ethanol than is the case with bio-ethanol84
Since 2011 Audi has also been collaborating with Joule to produce e-diesel Finally in November 2014 Audi
opened a research facility in Dresden with project partners Climeworks and the start-up Sunfire in order to
produce its first batches of synthetic diesel combining two innovative technologies CO2 capture from the
ambient air (Climeworks) and the power-to-liquid process for the production of synthetic fuel (Sunfire)85
Currently Audi is investing in carbon capture and utilisation technologies
Electronics companies
Electronics companies such as Siemens are also investing in carbon capture technologies Developers at
Siemens Corporate Technology (CT) in Munich are currently active in the project CO2-to-value The challenge
of the project is to charge only carbon dioxide with electrons and not the surrounding water molecules
because the latter would merely result in the production of conventional hydrogen Specialists at the University
of Lausanne in Switzerland and materials scientists at the University of Bayreuth are working with Siemens to
develop catalysts on their behalf Siemens takes on a pragmatic approach by focusing on only one step in the
AP process They are not yet trying to capture light Instead they are centring their research activities on
activating CO2 and converting it into products such as (i) ethylene which the chemical industry needs for the
production of plastics (ii) methane the main component of natural gas and (iii) carbon monoxide which can
be used to produce fuels such as ethanol86
Other companies
Figure 46 illustrates the process of NewCO2Fuels (NCF) an Israeli company focused on carbon capture
This is a high-temperature-driven CO2- and water-dissociation process that produces syngas (a mixture of
CO and H2) from which various synthetic fuels and chemicals can be produced
In the short term NCF is focusing on the design and building of a first pilot plant as well as raising the
necessary funds for it
In the mid term NCF plans to offer its technology to the energy intensive industries such as the steel
gasification and glass industries to transform their CO2 waste streams into feedstock
In the long term NCFrsquos vision is to use solar energy to convert CO2 captured immediately from the
atmosphere into valuable products
84
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 85
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 86
httpwwwsiemenscominnovationenhomepictures-of-the-futureresearch-and-managementmaterials-science-and-processing-co2tovaluehtml
85
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels
Source httpwwwnewco2fuelscoilproduct8overview
Furthermore some companies focus on chemical or biological CO2-to-fuel production Examples of
companies that focus on direct (co-electrolysis) CO2 to fuels production are Carbon Recycling (Iceland) and
Econic (UK ndash carbon capture) The company Liquid Light (US ndash carbon capture) focuses on the
electrochemical conversion of CO2 to chemicals
Other companies involved in carbon capture are Global Thermostat (US) Quantiam (Canada) Carbon
Engineering (Canada) Evonik Industries AG (Germany) and Haldor Topsoe (Denmark) Besides co-
electrolysis Catalytic Innovations Opus 12 and Lanzatech are also involved in carbon capture Mitsui
Chemical is focusing on carbon capture as well as photoelectrocatalysis
457 Assessment of the capabilities of the industry to develop AP technologies
Although there is a lot of research activity going on in the field of AP both at the academic and industrial level
the technology is clearly not yet ready for commercialisation However concrete test facilities and prototypes
are being developed and solar fuels have already been produced at a laboratory scale The technology is not
yet sufficiently efficient in order to be able to compete with other technologies producing comparable
chemicals and fuels Finding catalysts which are on the one hand Earth-abundant non-toxic and inexpensive
and on the other hand sufficiently efficient seems to be the biggest challenge With respect to the
technological efficiency of the AP processes the main bottlenecks are light capture (whole spectrum) getting
a good photocurrent density and using these charge carriers efficiently87
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade In September 2014 Panasonic Corporation managed to achieve a conversion
efficiency rate of 03 becoming the first to exceed the rate of 02 for regular plants In November 2014
Toshiba reached 15 which was followed by 20 achieved by the Japan Technological Research
Association of Artificial Photosynthetic Chemical Process (ARPChem) in February 2015 In February 2016
Toyota Central RampD Labs Inc announced that they achieved the worldrsquos highest energy conversion
efficiency rate of 46 with artificial photosynthesis by developing a semiconductor substrates-using iridium
and ruthenium catalyst They succeeded in increasing the efficiency rate a hundred-fold (an efficiency rate of
004 had been in achieved by Toyota in 2011)88
Figure 47 summarizes these efficiency rate developments
Several companies (eg Toshiba) hint at achieving efficiency rates of 10 and the first practical applications
87
httpwwwosa-opnorghomearticlesvolume_24february_2013featuresartificial_photosynthesis_saving_solar_energy_for 88
httpswwwasiabiomassjpenglishtopics1603_01html
86
of AP in the 2020s ARPChem aims to achieve a 10 level of energy conversion efficiency in 2021 (the rate
at which the manufacturing of raw materials for chemicals becomes economically viable)89
Figure 47 Transition of energy conversion efficiency of artificial photosynthesis
Source httpswwwasiabiomassjpenglishtopics1603_01html
It can also be observed that the big industrial investors in AP technology (research) already built interesting
partnerships with research centres and new innovative start-upscompanies For example
Audi works together with the innovative company Joule Unlimited (US) on the development of biologically-
derived e-ethanol and e-diesel and also works together with start-up company Sunfire on the production
of synthetic diesel
Siemens works together with specialists at the University of Lausanne in Switzerland and at the University
of Bayreuth Germany on innovative catalysts
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University
(US) that works on the water-splitting and CO2 reduction process and
Mitsubishi is one of the five industrial partners in the Japanese ARPChem programme (2012-2021)
focusing on artificial photosynthesis research in which various Japanese universities will be involved
(including Waseda University and Tokyo University)
46 Summary of results and main observations
The aim of this report was to gain an understanding and a clear overview of the main European and global
actors active in the field of artificial photosynthesis This has been achieved by
Identifying the main European and global actors active in the field of AP
Providing an assessment of the current level of investments in AP technologies
Assessing the key strengths and weaknesses of the main actors and
Assessing the capabilities of the industry to develop and exploit the AP technologies
Fuelled by the globally perceived need to find a green non-polluting and emission neutral energy source for
the future there has been much development in the field of artificial photosynthesis and considerable progress
has been made In addition the emergence of multiple consortia and governmental programmes and
international conferences in the last 10-15 years suggest that there is a higher awareness of the potential of
89
httpwwwmitsubishichem-hdcojpenglishcsrdownloadpdf13_25pdf
87
AP and that further advances are necessary The analysis has shown that although there have been some
promising developments especially in collaboration with industry much remains to be done for AP
technologies and processes to become commercially viable Milestones which will spur the development and
commercialisation process of AP encompass increased global and industry cooperation and the deployment
of targeted large-scale innovation projects following the example of the US innovation hubs
A summary of the results of the analysis and the main observations concerning the research and industry
actors active in the field of artificial photosynthesis is presented below It should be noted that the academic
and industrial community presented in this report is not exhaustive and especially with increasing interest in
AP more actors are expected to become active in the field
Research community
In general we observe that AP research has been intensified during the last decade given the increasing
number of emerging networks and communities We identified more than 150 research groups on AP
worldwide out of which more than 60 are located in Europe Due to the interdisciplinary character of AP
research combines expertise from biology biochemistry biophysics and physical chemistry The development
of research networks and consortia facilitates collaboration between different research groups and enables
them to benefit from synergies We identified six consortia in Europe and five outside of Europe respectively
Almost all of them are based in a specific country attracting primarily research groups from that country Only
one consortium AMPEA launched by the European Energy Research Alliance is truly pan-European with a
range of members across the EU
Table 415 Summary of findings size of research community
Number of research groups
Total in Europe 113
Number of research groups per pathway
Synthetic biology amp hybrid systems 53
Photoelectrocatalysis 69
Co-electrolysis 25
Total outside Europe 77
Number of research groups per pathway
Synthetic biology amp hybrid systems 30
Photoelectrocatalysis 59
Co-electrolysis 14
Source Ecorys
With respect to the three technology pathways (synthetic biology amp hybrid systems photoelectrocatalysis and
co-electrolysis) we observed that almost 85 of the research activities worldwide are focused on the first two
pathways (about 34 on the first pathway and 50 on the second) whereas the third pathway attracts only
about 16 of the research communityrsquos attention Only the Dutch AP consortium BioSolar Cells specifically
focuses on co-electrolysis Other consortia like ARPChem in Japan collaborating with industry prefer to
research artificial photosynthesis via photoelectrochemical catalysis as this pathway is the most mature and
with the highest probability of successful commercialisation
The diversity of the scientists involved is the biggest strength of this global AP research community
Furthermore all of the existing technological pathways in AP are covered which avoids lock-ins into one
pathway and increases the probability of success for AP in general AP is on the research agenda of several
countries which is proven by the existence of dedicated programmes roadmaps and funds Globally several
hundreds of millions of euros are being spent this decade on AP research and these investments seem to be
intensifying further Major shortcomings encompass a lack of cooperation between research groups in
88
academia on the one hand and between academia and industry on the other A more technical challenge is
the transfer of scientific insights into practical applications and ultimately into commercially viable products
The AP sector in Europe exhibits some strengths in comparison to its non-European counterparts but also
some weaknesses Europersquos scientific institutions are strong and its researchers highly educated
Furthermore RampD institutions and research facilities are available providing a solid ground for research
Some individual MS have their own research programmes roadmaps and funds Nevertheless the investment
does not reach the amount of funds available in some non-European countries and is rather short-term in
comparison to that of its non-European counterparts Furthermore both the national research plans and their
funding seem fragmented and scattered lacking an integrated approach with common research goals and
objectives At the European level however collaboration has been successful within several ongoing and
conducted FP7 projects Close collaboration between research groups could also be achieved through the
establishment of consortia Apart from the pan-European consortium AMPEA collaboration between research
groups of different countries is limited the consortia are primarily country-based and attract mostly research
groups from that respective country Lastly the level of collaboration between academia and industry seems
to be more limited in Europe compared to that within the US or Japan
Industrial actors
At this moment the number of companies active in the field of AP is limited AP is still mainly at the laboratory
level Most pathways are still at level 1 or 2 of technology readiness (TRL) implying that research is still being
conducted and used to improve feasibility Only co-electrolysis is at a more advanced stage and most
methods are already commercially viable
Based on our analysis of the main AP actors in the industry only several tens of companies appear to be
active in this field Moreover the industrial activity is limited to research and prototyping as viable AP
technologies are not (yet) in commercial operation The pathways synthetic biology amp hybrid systems and
photoelectrocatalysis are still at the lowest levels of technology readiness Research within the
photoelectrocatalysis pathway is still at an early stage as well however PV devices (semiconductor devices
similar to the ones used in PEC devices) have already been successfully commercialised Co-electrolysis on
the other hand is a technology already available for a longer time period in this pathway various
technologies to convert water and DC electricity into gaseous hydrogen and oxygen are already
commercialised In contrast the technologies producing hydrocarbons by Fischer-Tropsch synthesis
converting for example CO2 H2O and syngas into hydrocarbon fuels are still at an earlier stage of
development Co-electrolysis is therefore at a 1-9 TRL having both already commercialised technologies as
well as the Fischer-Tropsch synthesis
In total we have identified and analysed 33 industrial actors active in the field of AP 15 European and 18 non-
European industrial actors With respect to the industry largely the same countries stand out as in the
research field namely Japan the US and north-western Europe The industry in Japan appears to have the
most intensive research activities in AP as several large Japanese multinationals have set up their own AP
RampD laboratoriesresearch departments With respect to the three technology pathways we can observe that
most industrial (research) activity is being performed concerning photoelectrocatalysis
89
Table 416 Summary of findings size of industrial community
Number of companies
Total in Europe 15
Number of companies per pathway
Synthetic biology amp hybrid systems 6
Photoelectrocatalysis 9
Co-electrolysis 1
Total outside Europe 18
Number of companies per pathway
Synthetic biology amp hybrid systems 3
Photoelectrocatalysis 11
Co-electrolysis 5
Source Ecorys
The main hurdles in the synthetic biology amp hybrid systems pathway relate to the improvement of efficiency
and protein production speeds as well as stability and solubility by rational design With respect to the
technological efficiency of the AP processes relating to photoelectrocatalysis the main bottlenecks are light
capture (whole spectrum) obtaining a good photocurrent density and using these charge carriers efficiently
Co-electrolysis is mainly facing challenges to increase the lifetime of the devices to create concept on a
megawatt scale to search for substitution of noble metal catalysts and to develop technologies that are
capable of supplying the electricity required Furthermore some methods are still at a low TRL like the
Fischer-Tropsch synthesis Finding catalysts which are Earth-abundant non-toxic inexpensive and
sufficiently efficient remains a huge challenge To this end more public and private funding is needed
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade For example between 2011 and 2016 Toyota Central RampD labs made a significant
leap forward from an efficiency rate of 004 towards an efficiency rate of 46 Furthermore several
industrial actors (including Toshiba and ARPChem) have hinted at being able to achieve efficiency rates of
10 and the first practical applications of AP in the 2020s When academia are able to overcome the main
barriers with respect to AP the TRL will increase and the interest in AP from the industries will rise More
interest from the industries is necessary in order to push AP on the market and making it an economically
viable alternative renewable energy source
91
5 Factors limiting the development of AP technology
The overall concept followed in this study is to assess a number of selected ongoing research technological
development and demonstration (RTD)initiatives andor technology approaches implemented by European
research institutions universities and industrial stakeholders in the field of AP (including the development of
AP devices)
Seven AP RTD initiatives have been identified for the assessment of ldquolimiting factorsrdquo addressing the three
overarching technology pathways synthetic biology amp hybrid systems photoelectrocatalysis of water (water
splitting) and co-electrolysis (see Table 51)
The authors are confident that through the assessment of these selected European AP RTD initiatives a good
overview of existing and future factors limiting the development of artificial photosynthesis technology (in
Europe) can be presented However it has to be noted that additional AP RTD initiatives by European
research institutions universities and industrial stakeholders do exist and that this study does not aim to prove
a fully complete inventory of all ongoing initiatives and involved stakeholders
Table 51 Overview of the selected AP research technological development and demonstration (RTD) initiatives
AP Technology
Pathways AP RTD initiatives for MCA
Synthetic biology amp
hybrid systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Biocatalytic conversion of CO2
into formic acid ndash Bio-hybrid
systems
Photoelectrocatalysis
of water (light-driven
water splitting)
Direct water splitting with bandgap absorber materials and
catalysts
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
a) Direct water splitting with III-
V semiconductor ndash Silicon
tandem absorber structures
b) Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Co-electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
Electrolysis cells for CO2
valorisation ndash Industry
research
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges
Until today much progress has been made in the development of artificial photosynthetic systems
However a number of significant scientific and technological challenges remain to successfully scale-up
existing laboratory prototypes of different AP technology approaches towards a commercial scale
In order to ensure that AP technologies become an important part of the (long-term) future sustainable
European and global energy system and additionally provide high-value and low carbon chemicals for
industrial applications AP based production systems need to be
Efficient so that they utilise as much sunlight as possible to produce fuels andor chemicals The larger
the fraction of sunlight that can be converted to chemical energy the fewer materials and less land would
be needed for AP devices A target efficiency of about 10 (for AP based fuel production) is an initial goal
This is about ten times the efficiency of natural photosynthesis however it should be noted that AP
92
laboratory prototype devices with solar-to-hydrogen efficiencies of 5 and more have already been
developed
Durable so that AP systems can convert a lot of energy in their lifetime relative to the energy required for
the production and installation of the devices This is a significant challenge because some materials
degrade quickly when operated under the special conditions of illumination by discontinuous sunlight
Cost-effective meaning the raw materials needed for the production of the AP devices have to be
available at a large scale and the produced fuels andor chemicals have to be of commercial interest
Resource-efficient so that they minimise the use of rare and expensive raw materials (taking into
account trade-offs between material abundancy cost and efficiency)
Today significant improvements with respect to cost-efficiency lifetimedurability energy efficiency and
resource use are still required for all existing AP technology approaches
Table 52 provides an overview of the current and target performance for the assessed seven AP research
technological development and demonstration (RTD) initiatives within the three overarching technology
pathways of synthetic biology amp hybrid systems photoelectrocatalysis and co-electrolysis
93
Table 52 Overview of the current and target performance with respect to cost-efficiency lifetimedurability energy efficiency and resource use
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
Nitrogenase
activity wanes
within a few
days
Light energy
conversion
efficiency
gt10
(theoretical
limit ~15)
4 (PAR
utilization
efficiency) on
lab level (200 x
600 mm)
No data No data
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
CO2 reduction
energy
efficiency (full
system) gt10
(nat PS ~1)
NA (CO2
reduction
energy
efficiency for
full system) on
lab level
No data No data
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
gt500 hours
(stability goal)
gt40 hours
Solar-to-
hydrogen
(STH)
efficiency
gt17
STH efficiency
14
Reduction of
use of noble
metal Rh
catalyst and
use of Si-
based
substrate
material
1kg Rh for
1MW
electrochem
power output
Ge substrate
(for
concentrator
systems)
Si substrate
94
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Bandgap abs materials
Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency ~9
STH efficiency
49
Reduction of
use of rare Pt
catalyst
Pt used as
counter
electrode for
H2 production
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency
gt10
IPCE gt90
(efficiency
goal)
IPCE (incident
photon to
electron
conversion
efficiency) of
25
Reduction of
use of rare and
expensive raw
materials
High-cost Ru-
based photo-
sensitizers
used
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
SOFC capital
cost target
400 US$kW
Comp of
synthetic fuels
with fossil fuels
No data
gt20 years
(long term)
1000 hours
(stability goal)
~50 hours
(high SOEC
cell
performance
degradation
observed)
Power-to-
Liquid system
efficiencies
(full system
incl FT)
gt70
No data No data No data
Electrolysis cells for CO2
valorisation ndash Industry
research
Comp with
fossil chemi
and fuels (eg
CO ethylene
alcohols) 650-
1200 EURMt
No data
gt20 years
(long term)
10000 hours
(stability goal)
gt1000 hours
(laboratory
performance)
System
efficiencies
(full system)
gt60-70
95 of
electricity used
to produce CO
System
efficiencies
(full system)
40
No data No data
95
52 Current TRL and future prospects of investigated AP RTD initiatives
Table 53 presents an overview of the current TRL future prospects and an estimation of future required
investments for the assessed AP research technological development and demonstration (RTD) initiatives
It should be noted that due to the focus on specific selected AP RTD initiatives the investment requirements
listed below do not represent all of the RTD activities conducted by European research institutions
universities and industrial stakeholders within the three overarching technology pathways of synthetic biology
amp hybrid systems photoelectrocatalysis and co-electrolysis
Table 53 Overview of current TRL future prospects and estimated investment needs for investigated AP RTD initiatives
AP RTD Initiatives TRL achieved (June
2016)
Future Prospects Estimated Investment
needed
Photosynthetic microbial cell
factories based on cyanobacteria
TRL 3 (pres Init)
TRL 6-8 (for direct
photobiol ethanol prod
with cyanobacteria green
algae)
2020 TRL 4 (pres Init)
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Biocatalytic conversion of CO2 into
formic acid ndash Bio-hybrid systems TRL 3 2020 TRL 4
Direct water splitting with III-V
semiconductor ndash Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 (for III-VGe
tandem structures)
TRL 3 (for III-VSi tandem
structures)
2020 TRL 5 (for III-VGe
tandem structures)
2021 TRL 5 (for III-VSi
tandem structures)
Basic RTD 5-10 Mio euro
TRL 5 5-10 Mio euro
Direct water splitting with Bismuth
Vanadate (BiVO4) - Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 2020 TRL 5
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
TRL 3 2020 TRL 4
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
TRL 2-3 (for co-
electrolysis of H2O
(steam) and CO2)
2020 TRL 3-4 (for co-
electrolysis of H2O
(steam) and CO2)
Electrolysis cells for CO2
valorisation ndash Industry research
TRL 4 (for RE assisted
carbon compound
production)
TRL 3 (for full synthetic
photosynthesis systems)
2020 TRL 6 (for RE
assisted carbon
compound production)
2020 TRL 5 (for full
synthetic photosynthesis
systems)
TRL 6 10-20 Mio euro
53 Knowledge and technology gaps of investigated AP RTD initiatives
At present a number of significant scientific and technological challenges remain to be addressed before
successfully being able to scale-up existing laboratory prototypes of different AP technology approaches
towards the commercial scale
Table 54 presents an overview of the identified knowledge and technology gaps focusing on the assessed
AP research technological development and demonstration (RTD) initiatives
96
Table 54 Overview of knowledge and technology gaps of investigated AP RTD initiatives
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Photosynthetic microbial cell
factories based on
cyanobacteria
Further metabolic and genetic engineering of the strains
Further engineered cyanobacterial cells with respect to increased light
harvesting capacity
Streamlined metabolism toward hydrogen production for needed electrons
proteins and energy instead of being used in competing pathways
More efficient catalysts with higher turnover rates
Simple and reliable production systems allowing higher photosynthetic
efficiencies and the use of optimal production conditions
Efficient mechanisms and systems to separate produced hydrogen from other
gases
Cheaper components of the overall system
Investigation of the effect of pH level on growth rate and hydrogen evolution
Production of other carbon-containing energy carriers such as ethanol
butanol and isoprene
Improvements of the photobioreactor design
Up-scaling of photobioreactor (from present active surface of 200 x 600 mm)
Improvement of operating stability (from present about gt100 hours)
Improvement of PAR utilisation efficiency from the present 4 to gt10
Cost reduction towards a hydrogen production price of 4 US$ per kg
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Further metabolic and genetic engineering of strains
Reduction of reactive oxygen species (ROS) which are detrimental to cell
growth
Development of biocompatible catalyst systems that are not toxic to bacteria
Development of ROS-resistant variants of bacteria
Development of hybrid systems compatible with the intermittent nature of the
solar energy source
Development of strains for CO2 reduction at low CO2 concentrations
Metabolic engineering of strains to facilitate the production of a large variety of
chemicals polymers and fuels
Enhance (product) inhibitor tolerance of strains
Further optimisation of operating conditions (eg T pH NADH concentration
ES ratio) for high CO2 conversion and increased formic acid yields
Integration of enzymes into the hydrogen evolving part of ldquobionic leafrdquo devices
Mitigation of bio-toxicity at systems level
Improvements of ldquobionic leafrdquo device design
Up-scaling of ldquobionic leafrdquo devices
Improvement of operating stability (from present about gt100 hours)
Improvement of CO2 reduction energy efficiency towards gt10
Cost reduction of the production of formic acids and other chemicals
polymers and fuels
97
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Increased understanding of surface chemistry at electrolyte-absorber
interfaces
Further improvement of functionalization to achieve higher stabilities without
the need for protective layers
Reduction of defects acting as recombination centres or points of attack for
(photo)corrosion
Reduction of pinhole formation leading to reduced mechanical stability of the
Rh catalyst
Reduction of the amount of rare and expensive catalysts by the use of core-
shell catalyst nanoparticles with a core of an earth-abundant material
Reduction of material needed as substrate by employment of lift-off
techniques or nanostructures
Deposition of highly efficient III-V tandem absorber structures on (widely
available and cheaper) Si substrates
Development of III-V nanowire configurations promising advantages with
respect to materials use optoelectronic properties and enhanced reactive
surface area
Reduction of charge carrier losses at interfaces
Reduction of catalyst and substrate material costs
Reduction of costs for III-V tandem absorbers
Development of concentrator configurations for the III-V based
photoelectrochemical devices
Improvement of device stability from present gt40 hours towards the long-term
stability goal of gt500 hours
Improvement of the STH production efficiencies from the present 14 to
gt17
Cost reduction towards a hydrogen production price of 4 US$ per kg
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Improvements of the light absorption and carrier-separation efficiency
(currently still at lt60) in BiVO4
Better utilization of the solar spectrum by BiVO4 especially for wavelengths
close to the band edge (eg by plasmonic- andor resonance-enhanced
optical absorption)
Further development of novel water-oxidation catalysts based on for example
cobalt- and iron oxyhydroxide-based materials
Further development of the distributed n+ndashn homojunction concept for
improving carrier separation in high-donor density photoelectrode material
Improvement of the stability and avoidance of mass transport and light
scattering problems in devices based on nanoporous materials and DSSC
(Dye Sensitised Solar Cells)
Further development of Pulsed Laser Deposition (PLD) for (multi-layered)
WO3 and BiVO4 photoanodes
Although the near-neutral pH of the electrolyte solution ensures that the BiVO4
is photochemically stable proton transport is markedly slower than in strongly
alkaline or acidic electrolytes
Design of new device architectures that efficiently manage proton transport
and avoid local pH changes in near-neutral solutions
For an optimal device configuration the evolved gasses need to be
transported away efficiently without the risk of mixing
The platinum counter electrode needs to be replaced by an earth-abundant
alternative such as NiMo(Zn) CoMo or NiFeMo alloys
Improvement of device stability from present several hours towards the long-
term stability goal of 1000 hours
Scaling up systems to square meter range
Improvement of the STH production efficiencies from the present 49 to ~9
Cost reduction towards a hydrogen production price of 4 US$ per kg
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Deep molecular-level understanding of the underlying interfacial charge
transfer dynamics at the SCdye catalyst interface
Novel sensitizer assemblies with long-lived charge-separated states to
Design and construction of functional DS-PECs with dye-sensitised
photoanodes and dye-sensitised photocathodes (tandem DS-PEC structures)
Design and construction of DS-PECs where undesired external bias is not
98
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
enhance quantum efficiencies
Sensitizerndashcatalyst supramolecular assembly approach appears as effective
strategy to facilitate faster intramolecular electron transfer for long-lived
charge-separated states
Optimise the co-adsorption for efficient light-harvesting and charge collection
Organometal halide perovskite compounds as novel class of light harvesters
(for absorber applications in DS-PEC)
Encapsulation of perovskite compounds to prevent the dissolution in aqueous
solutions
Semiconductor quantum dots (QDs) as suitable sensitizers for DS-PEC
Exploration of more efficient OERHER catalysts with low overpotentials
Use of a redox mediator analogous to the tyrosine-histidine pair in PSII to
accelerate dye regeneration and thus achieve an increased charge
separation lifetime
One-dimensional TiO2 nanostructures such as TiO2 nanotubes and nanorods
to improved the charge transport properties and thus charge collection
efficiencies
Exploration of alternative SC oxides with more negative CB energy levels to
match the proton reduction potential
Search for alternative more transparent p-type SCs with slower charge
recombination and high hole mobilities
Further studies on phenomena of photocurrent decay commonly observed in
DS-PECs under illumination with time largely due to the desorption andor
decomposition of the sensitizers andor the catalysts
needed
Design and construction of DS-PECs with enhanced quantum efficiency
(towards 90 IPEC)
Ensure dynamic balance between the two photoelectrodes in order to properly
match the photocurrents
Development of efficient photocathode structures
Ensure long-term durability of molecular components used in DS-PEC devices
Reduce photocurrent decay due to the desorption andor decomposition of the
sensitizers andor the catalysts
Ensure active photosensitizer and catalyst for at least millions of cycles in 20ndash
30 years
Ensure long operating lifetimes (such as achieved for DSC) for stable DS-PEC
devices that incorporate molecular components Future work on developing
robust photosensitizers and catalysts firm immobilization of sensitizercatalyst
assembly onto the surface of SC oxide as well as the integration of the robust
individual components as a whole needs to be addressed
Scaling up systems to square meter range
Improvement of the STH production efficiencies IPCE (incident photon to
electron conversion efficiency) need to be improved from ~25 to gt90
Cost reduction towards a hydrogen production price of 4 US$ per kg
99
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Basic understanding of reaction mechanisms in co-electrolysis of H2O (steam)
and CO2
Basic understanding of dynamics of adsorptiondesorption of gases on
electrodes and gas transfer during co-electrolysis
Basic understanding of material compositions microstructure and operational
conditions
Basic understanding of the relation between SOEC composition and
degradation mechanisms
Development of new improved materials for the electrolyte (eg Sr- and Mg-
doped lanthanum gallate (LSGM) and scandium-stabilized zirconia (Sc- SZ))
Development of new improved materials for the electrodes (eg Sr- and Fe-
doped lanthanumcobaltate (LSCF)Sr-doped lanthanum ferrite (LSF)Co-
and Nb-doped barium ferrite (BCFN) and Sr- and Fe-barium cobaltate
(BSCF) perovskites)
Avoidance of agglomeration of Ni-particles and micro-cracks in Ni-YSZ
hydrogen electrodes
Avoidance of mechanical damages (eg delamination of oxygen electrode) at
electrolyte-electrode interfaces
Reduction of carbon (C) formation during co-electrolysis
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Replacing metallic based electrodes by pure oxides
Studies of long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O (steam) and CO2
Improvement of stability performance (from present ~50 hours towards the
long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Improvement of the co-electrolysis syngas production efficiencies towards
values facilitating the production of competitive synthetic fuels via FT-
processes
Cost reduction towards competitiveness of synthetic fuels with fossil fuels
Electrolysis cells for CO2
valorisation ndash Industry
research
Further research on catalyst development
Investigation of catalyst surface structure (highly reactive surfaces)
Catalyst development for a variety of carbon-based chemicals and fuels
Research on electrolyte composition and performance (dissolved salts current
density)
Research on light-collecting semiconductor grains enveloped by catalysts
Research on materials for CO2 concentration
Careful control of catalyst manufacturing process
Precise control of reaction processes
Development of modules for building facades
Stable operation of lab-scale modules
Stable operation of demonstration facility
Improvement of production efficiencies for carbon-based chemicals and fuels
Cost reduction towards competitiveness of the produced carbon-based
chemicals and fuels
100
54 Coordination of European research
Although RTD cooperation exists between universities research institutions and industry from different
European countries the majority of the activities are performed and funded on a national level Thus at
present the level of cooperation and collaboration on a pan-European level seems to be limited
There are few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7
projects and many research groups that are operating locally and are funded by national governments A low
degree of collaboration among different research groups was reported which results in a duplication of efforts
and a lack of generalized standards Synergies which could potentially boost research in artificial
photosynthesis are being overlooked Creating for example a communication platform to facilitate exchange
among actors could more easily promote the development of knowledge and increase the speed of discovery
and exploitation of new robust (effective and durable) photocatalysts innovative processes and devices etc
Another indicated weakness is the lack of collaboration between the already existing and ongoing projects
The coordination of research at a European level is mainly performed by AMPEA The European Energy
Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials amp Processes for Energy
Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging Technologies Artificial
photosynthesis became the first energy research subfield to be organised within AMPEA The goal of this joint
programme which was launched at the end of 2011 is to set up a thorough and systematic programme of
directed research which by 2020 will have advanced the technology to a point where commercially viable
artificial photosynthetic devices will be under development in partnership with industry
Currently AMPEA does not involve biological AP approaches as its main mission focuses on advanced
materials Therefore opportunities for research cooperation in the field of synthetic biology seem limited in the
short term
Furthermore it was stated that the current effectiveness of AMPEA to coordinate research at a European level
is limited also due to budget constraints and limited direct funding provided to AMPEA
Specifically efforts within AMPEA are currently centred on developing a concise RTD roadmap for AP
technologies in Europe The future implementation of this roadmap will require support on both national and
European levels
Table 55 (below) presents a list of European research collaborations within the investigated AP research
technological development and demonstration (RTD) initiatives
101
Table 55 (European) research cooperation within the investigated AP RTD initiatives
AP RTD Initiatives (European) Research cooperation
Photosynthetic microbial
cell factories based on
cyanobacteria
Initiative implemented by Uppsala University Sweden (within CAP) in cooperation with
Norwegian Institute of Bioeconomy Research (NIBIO)
Existing cooperation between Uppsala University and German car manufacturer VW
Biocatalytic conversion of
CO2 into formic acid ndash
Bio-hybrid systems
Initiative implemented by Wageningen UR Food amp Biobased Research and Wageningen UR
Plant Research International The Netherlands (within BioSolar Cells)
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
III-V semiconductor ndash
Silicon tandem absorber
structures
Initiative implemented by TU Ilmenau the Institute for Solar Fuels at the Helmholtz-Zentrum
Berlin and the Fraunhofer Institute for Solar Energy Systems ISE and the California Institute
of Technology (Caltech)
Existing cooperation between TU Ilmenau and epitaxy technology providers Space Solar
Power GmbH and Aixtron SE
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
Bismuth Vanadate
(BiVO4) - Silicon tandem
absorber structures
Initiative implemented by the Institute for Solar Fuels at the Helmholtz-Zentrum Berlin and
two Departments at Delft University of Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Further RTD was done at Repsol Technology Center from Spain in cooperation with
Catalonia Institute for Energy Research (IREC)
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
Initiative implemented by KTH Royal Institute of Technology Sweden in cooperation with
Dalian University of Technology China (within CAP)
Further RTD at University of Amsterdam (within BioSolar Cells) University of Grenoble
University of Cambridge and EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Existing cooperation between OMV and University of Cambridge
Existing cooperation between Siemens and EPFL
Co-electrolysis of steam
and carbon dioxide in
Solid Oxide Electrolysis
Cells (SOEC)
RTD performed at Technical University of Denmark Imperial College London University of
Sheffield and in previous years by Catalonia Institute for Energy Research (IREC) in
cooperation with Repsol Technology Center from Spain
Electrolysis cells for CO2
valorisation ndash Industry
Research
Initiative implemented by Siemens Corporate Technology (CT) in cooperation with the
University of Lausanne and the University of Bayreuth Germany
55 Industry involvement and industry gaps
Due to the low TRL (TRL 2-4) of present AP technology pathways in the areas of synthetic biology amp hybrid
systems photoelectrocatalysis of water (water splitting) and co-electrolysis the direct involvement of industry
in research and development activities in Europe is currently limited
Furthermore detailed information on industry activities in the AP field is difficult to find also due to issues of
confidentiality According to Cefic (European Chemical Industry Council) AP is regarded as a potentially
promising future technology option by the Councilrsquos members however information on industry involvement is
largely kept confidential
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research including
research in artificial photosynthesis However while companies are participating in local consortia such as
BioSolar Cells there currently seems to be a lack of cooperation between academia and industry at an
international level
102
Industry involvement in the area of synthetic biology amp hybrid systems
There is ongoing cooperation between Uppsala University and the German car manufacturer Volkswagen
within the framework of the European project ldquoPhotoFuelrdquo The project is coordinated by VW and focuses on
the production of butanol using micro-organisms
The European industry end users Volvo and VW are involved in the field of the design and engineering of
photosynthetic microbial cell factories based on cyanobacteria however are not directly involved in the
development of micro-organisms themselves
Furthermore in the USA the company Algenol Biofuels Inc is active in the field and operating a pilot scale
production unit
Industrial partners potentially interested in the development of ldquobionic leavesrdquo include the industry partners of
the Dutch BioSolar Cells programme Currently the coupling of the developed enzymes to the hydrogen-
evolving part of the device (ie the development of a full ldquobionic leafrdquo) is subject to ongoing patent procedures
by researchers of Wageningen UR
Industry involvement in the area of photoelectrocatalysis of water (water splitting)
The processes used for the deposition and processing of the devices based on two-junction tandem absorber
structures namely the metal-organic vapour phase epitaxy (MOCVD) and the in-situ functionalisation of
surfaces are generally scalable to an industrial level Spray pyrolysis processes used for the deposition of
dense thin films of BiVO4 are well-established industrial technologies and thus generally scalable to an
industrial level
Industrial stakeholders potentially interested in the area of direct water splitting with tandem absorber
structures include industry partners active in the field of epitaxy technology (eg producers and technology
providers such as Azur Space Solar Power GmbH and Aixtron SE which have ongoing long-term cooperation
with TU Ilmenau) suppliers of industrial process and specialty gases (eg Linde Group) and chemical
industries involved in catalytic processes (eg BASF Evonik)
Further interested industrial stakeholders include industry partners of the network Hydrogen Europe
(httphydrogeneuropeeu) and the Fuel Cells and Hydrogen Joint Undertaking (FCH JU
httpwwwfcheuropaeu) Hydrogen Europe (formerly known as NEW-IG) is the leading industry association
representing almost 100 companies both large and SMEs working to make hydrogen energy an everyday
reality The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) is a unique public-private partnership
supporting RTD activities in fuel cell and hydrogen energy technologies in Europe
The industry player Repsol from Spain was involved (on a research and development level) in the
development of photoelectrochemical water splitting based on metal oxides (WO3 BiVO4) through its Repsol
Technology Center in Spain in cooperation with the Department of Advanced Materials for Energy Catalonia
Institute for Energy Research (IREC) and the Department of Electronics University of Barcelona (UB) The
focus is currently centred on Pulsed Laser Deposition (PLD) for (multi-layered) WO3 and BiVO4 photoanodes
No full devices for photoelectrochemical water splitting have however yet been reported within this initiative
In the area of dye-sensitised PEC potentially interested industrial partners include the major fuel companies
Shell and Total who are already members of SOFI (Solar Fuels Institute based at Northwestern University)
an international research and innovation organisation with several European members (including the core
member Uppsala University) The Austrian fuel company OMV funds research at the Reisner Lab at the
Department of Chemistry at the University of Cambridge which is involved in both dye and catalyst
development
103
Successful technology transfer has recently been reported by Innovation Exchange Amsterdam (IXA) the
technology transfer office of the University of Amsterdam to the French company PorphyChem Rights were
licensed for the commercialisation of novel molecules for hydrogen generation so-called metalloporphyrins
innovative molecular photosensitizers which enable sustainable sunlight-driven hydrogen production from
water In cooperation with IXA the researchers filed patent applications with the European Patent Office on 26
February 2015 H-C Chen A M Brouwer Photosensitizer Europatent application 2015 EP15156740
The industry player Siemens AG from Germany is funding a project implemented by the Laboratory of
Photonics and Interfaces the Institute of Chemical Sciences and Engineering the School of Basic Sciences
and the Ecole Polytechnique Federale de Lausanne (EPFL) for the development of efficient photosynthesis of
carbon monoxide from CO2 using perovskite photovoltaics
Industry involvement in the area of co-electrolysis
Until today the involvement of industry in the research and development of the co-electrolysis of water and
carbon dioxide in Solid Oxide Electrolysis Cells (SOECs) in Europe is limited
Activities (on a research and development level) were performed by the industry player Repsol from Spain
through its Repsol Technology Center in cooperation with the Department of Advanced Materials for Energy at
the Catalonia Institute for Energy Research (IREC) The focus of these efforts is the replacement of metallic-
based electrodes by pure oxides offering advantages for industrial applications of solid oxide electrolysers
Thereby the aim is to ensure suitable H2CO ratios of the produced syngas (ie close to two) fulfilling the
basic requirements for synthetic fuel production
At present the focus of industrial engagement (eg sunfire Audi) for the production of synthetic carbon-based
fuels via concepts using (co)electrolysis and FT-processes favours water electrolysis (for the production of H2)
and the separate addition of CO2 in the FT-process over co-electrolysis of water and carbon dioxide
In April 2015 the company sunfire GmbH announced that it succeeded in producing synthetic diesel from air
water and green electrical energy A demonstration rig for power-to-liquids was inaugurated in November
2014 Recently the plant reached its full operating capacity and now produces synthetic diesel fuel Audi the
German car manufacturer and project partner of sunfire exposed the synthetic diesel to laboratory tests with
the result that the fuel was approved A larger plant needs to be developed in order to proceed towards a
commercial application of this process
An industry-driven approach towards the valorisation of carbon dioxide for the production of carbon-based
chemicals and fuels is implemented by Siemens Corporate Technology (CT) in Munich Germany This work is
implemented within the framework of the Siemens corporate project ldquoCO2toValuerdquo where catalyst
development is performed in cooperation with researchers from the University of Lausanne in Switzerland and
materials scientists at the University of Bayreuth
A small-scale lab unit based on an electrolyser cell is currently in operation at Siemens CT and a large-scale
demonstration facility is planned to be operational in the coming years in order to pave the way towards the
industrial application of this synthetic photosynthesis process for the production of carbon-based chemicals
and fuels to be introduced into the market
104
56 Technology transfer opportunities
The transfer of research to industrial application in artificial photosynthesis remains challenging In order to
attract the attention of the private sector artificial photosynthetic systems have to be cost-effective efficient
and durable The active involvement of industrial parties could help bring research prototypes to
commercialisation This step towards commercialisation requires sufficient critical mass and funding however
which cannot be borne by a single country
In the framework of the assessment of the seven AP technology approaches in the areas of synthetic biology
amp hybrid systems photoelectrocatalysis of water (water splitting) and co-electrolysis a number of ongoing
collaborations between research organisations and the industry as well as future opportunities for technology
transfer have been identified
Technology transfer opportunities in the area of synthetic biology
There are ongoing patent procedures by researchers at Wageningen UR on the coupling of developed
enzymes to the hydrogen-evolving part of the device (ie the development of a full ldquobionic leafrdquo)
Technology transfer opportunities in the area of photoelectrocatalysis of water (water splitting)
There are several patents filed by the researchers of TU Ilmenau and a patent on full device for direct
water splitting with III-V semiconductor based tandem absorber structures is under development
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC) and University of Barcelona (UB)
Successful technology transfer has been achieved by the technology transfer office of the University of
Amsterdam to the French company PorphyChem rights were licensed for the commercialisation of
metalloporphyrins as novel molecules for hydrogen generation which enable sustainable sunlight-driven
hydrogen production from water patent applications have been filed with the European Patent Office
There are technology transfer opportunities between OMV and the University of Cambridge and between
Siemens and EPFL on perovskite PV
Technology transfer opportunities in the area of co-electrolysis
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC)
There are technology transfer opportunities between Siemens and the University of Lausanne as well as
the University of Bayreuth
Table 56 below provides and overview of industry involvement and technology transfer opportunities
105
Table 56 Overview of industry involvement and technology transfer opportunities
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Uppsala University Sweden (within
CAP) in cooperation with Norwegian
Institute of Bioeconomy Research
(NIBIO)
Existing cooperation between Uppsala University
and German car manufacturer VW
Interest by end users Volvo and VW
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Wageningen UR Food amp Biobased
Research and Wageningen UR
Plant Research International The
Netherlands (within BioSolar Cells)
Industry partners of BioSolar Cells
Ongoing patent procedures by researchers of
Wageningen UR on the coupling of the developed
enzymes to the hydrogen evolving part of the
device (ie the development of a full ldquobionic leafrdquo)
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
TU Ilmenau Institute for Solar Fuels
at the Helmholtz-Zentrum Berlin and
the Fraunhofer Institute for Solar
Energy Systems ISE and the
California Institue of Technology
(Caltech)
Existing cooperation between TU Ilmenau and
epitaxy technology providers Space Solar Power
GmbH and Aixtron SE
Interest by suppliers of industrial gases (eg
Linde Group) and chemical industries involved
in catalytic processes (eg BASF Evonik)
Industry partners of network Hydrogen Europe
and the Fuel Cells and Hydrogen Joint
Undertaking (FCH JU)
Several patents filed by researchers of TU
Ilmenau
Patent on full device for direct water splitting with
III-V thin film based tandem absorber structures
under development
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Institute for Solar Fuels at the
Helmholtz-Zentrum Berlin two
Departments at Delft University of
Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
Further RTD at Repsol Technology
Center from Spain in cooperation
with Catalonia Institute for Energy
Research (IREC) and University of
Barcelona (UB)
RTD by Repsol Technology Center focus is
currently placed on Pulsed Laser Deposition
(PLD) for (multi-layered) WO3 and BiVO4
photoanodes No full devices for
photoelectrochemical water splitting have
however yet been reported
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC) and University of Barcelona (UB)
Dye-sensitised
photoelectrochemical cells -
molecular photocatalysis
KTH Royal Institute of Technology
Sweden in cooperation with Dalian
University of Technology China
Existing cooperation between OMV and
University of Cambridge
Existing cooperation between Siemens and
Successful technology transfer by technology
transfer office of University of Amsterdam to the
French company PorphyChem Rights were
106
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
(within CAP)
Further RTD at University of
Amsterdam (within BioSolar Cells)
University of Grenoble University of
Cambridge and EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
EPFL
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Fuel companies Shell and Total
licensed for the commercialisation of novel
molecules for hydrogen generation so-called
metalloporphyrins innovative molecular
photosensitizers which enable sustainable
sunlight-driven hydrogen production from water
Patent applications filed with the European Patent
Office
Technology transfer opportunities between OMV
and University of Cambridge and between
Siemens and EPFL on perovskite PV
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Technical University of Denmark
Imperial College London University
of Sheffield and Catalonia Institute
for Energy Research (IREC) in
cooperation with Repsol Technology
Center from Spain
RTD by Repsol Technology Center focus is the
replacement of metallic based electrodes by
pure oxides offering advantages for industrial
applications of solid oxide electrolysers
Sunfire and Audi (steam electrolysis and FT-
synthesis)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC)
Electrolysis cells for CO2
valorisation ndash Industry
research
Siemens Corporate Technology (CT)
in cooperation with the University of
Lausanne and the University of
Bayreuth Germany
Industry driven approach towards the
valorisation of carbon dioxide for the production
of carbon-based chemicals and fuels by
Siemens CT
Technology transfer opportunities between
Siemens and University of Lausanne University of
Bayreuth
107
57 Regulatory conditions and societal acceptance
The current very low oil prices as well as the low carbon price (ie the fee that must be paid for the right to
emit CO2 into the atmosphere) are hindering the market uptake of the low carbon AP-based production of
chemicals polymers and fuels (carbon-based fuels as well as hydrogen) In addition until today carbon
benefits are only monetised in the energy sector and not for the production of eg low carbon chemicals
Furthermore direct market incentives for solar fuels may be an opportunity for the future development of AP
technologies In addition investments made towards the establishment of a European infrastructure for
hydrogen storage and handling may be beneficial for the future development of AP technologies
Advancements in artificial photosynthesis have the potential to radically transform how societies convert and
use energy However their successful development hinges not only on technical breakthroughs but also on
the acceptance and adoption by energy users
It is therefore important to learn from experiences with other energy technologies (eg PV wind energy
nuclear energy biofuels) and thoroughly involve all societal actors in a discussion on the potential benefits
and drawbacks of the emerging technology already during the very early stages of development
Specifically barriers to social acceptance and issues causing public concern need to be addressed in an open
dialogue and potential measures mitigating concerns need to be discussed and implemented (where
possible) It needs to be kept in mind that the majority of the public is largely unaware of AP technologies
The following main topics are subject to public concern with respect to present AP technology pathways in the
areas of synthetic biology amp hybrid systems photoelectrocatalysis of water (water splitting) and co-
electrolysis
The use of genetic engineering and Genetically Modified Organisms (GMO) mainly for synthetic biology
approaches
The use of toxic materials for the production of AP devices which concerns all pathways
The use of rare and expensive raw materials for catalysts and absorber materials also for all pathways
Land use requirements for large-scale deployment of AP technology and land use competition with other
renewable energy options such as PV solar thermal applications and bioenergybiofuels
High societal costs involved in the development of AP technologies (efficiency and competitiveness of AP
technologies)
The importance of societal dialogue within the future development of AP technologies is widely acknowledged
within several national initiatives in Europe Initiatives on public involvement are implemented within the Dutch
BioSolar Cells programme and by the German National Academy of Science and Engineering (acatech)
109
6 Development roadmap
61 Context
611 General situation and conditions for the development of AP
Current energy technologies are unlikely to be sufficient to attain EU ndash and other international ndash long term
targets for the share of renewable energy sources in overall energy supplies beyond 2020 There is therefore
a strategic interest in supporting efforts to develop new energy technologies (and improve existing ones) and
to raise their competitiveness ndash eg in terms of costs efficiency and resource use ndash vis-agrave-vis those that are
currently available Thus from an energy policy perspective the motivation for accelerating the industrial
implementation of AP technologies arises from their potential to expand the available portfolio of competitive
sustainable energy sources thereby contributing to the continuation of the transition away from fossil fuels At
the same time from the perspective of growth and job creation developing and demonstrating the viability and
readiness for industrial deployment of AP technologies can be viewed as part of a wider industrial policy to
develop an internationally competitive European renewable energy technology industry
Processes based on AP have been identified as having the potential to deliver sustainable alternatives to
conventional fuels AP-based lsquowater-splittingrsquo processes may be used for the production of hydrogen or in
combination with lsquocarbon reductionrsquo for the production of carbon-based fuels (lsquosolar fuelsrsquo) and other higher
order carbon-based compounds However although AP technologies show great potential and despite the
significant progress in research in the AP field made in recent years there is still a significant way to go before
AP technologies are ready for industrial implementation
AP covers several technology pathways that are being developed in parallel and which are all at a low overall
level of technology readiness The individual processes sub-systems and components within the different
pathways are however at varying levels of maturity Consequently it is difficult to foresee the eventual
production efficiency costs and material requirements that could characterise future AP-based systems when
implemented on an industrial scale Moreover while it is possible that some AP technologies may end up
competing with each other complementarities and synergies may arise from AP technology development
activities that are currently being conducted largely in isolation from each other
To date application of AP has only been undertaken in small scale in laboratory conditions and the feasibility
of commercial industrial-scale deployment of AP systems has yet to be demonstrated Assuming that this can
be achieved at cost levels that enable AP-based products to be competitive in the marketplace commercial
implementation may raise some more practical issues for example in relation to land-use water availability
and other possible environmental or social concerns that have not as yet been fully explored
To appreciate the possible future role of AP technologies also requires consideration of other developments
shaping the energy supply and technology landscape Although by definition AP is concerned with the direct
conversion of solar energy into fuel technologies for specific processes developed within the context of AP
may eventually be linked to other renewable energy technologies for example if they are combined with
electricity generated from photovoltaics (PV) or other renewable sources such as wind energy Similarly the
production of lsquosolar fuelsrsquo using AP systems requires a source of carbon which may come in the form of CO2
from ambient air or alternatively by linking AP to carbon capture (and storage) systems90
90
See for example DG Research (2015) ldquoProceedings of the scoping workshop Transforming CO2 into value for a rejuvenated European economy Brussels 26th March 2015rdquo
110
Prospects for the future industrial implementation of AP technologies will not only depend on the lsquopushrsquo
provided by technological developments but will also depend on market lsquopullrsquo factors Not least the
commercial viability of fuels produced using AP technologies (and other renewable energy sources) will be
strongly influenced by price developments for other fuels particularly oil Current low oil and carbon
(emissions) prices must be taken into consideration as factors potentially hindering the market uptake of low
carbon AP-based production of chemicals polymers and fuels (including hydrogen) both now and in the
future
The overall market potential of solar fuels will also depend on public policy developments for example in
terms of regulatory frameworks and incentives affecting demand levels and costsprices of renewable energy
sources Similarly a concerted policy framework targeted towards promotion of a lsquohydrogen economyrsquo may
lead to a shift in emphasis for AP technology development towards hydrogen production (lsquowater splittingrsquo) ndash
already the more advanced area of AP research ndash and away from solar fuels Certainly until a higher
technology readiness level of AP is attained care should be taken to ensure that regulatory measures ndash
whether at European and national levels ndash do not impinge upon or hinder developments along the different AP
pathways
Finally in order to truly accelerate the industrial implementation of AP social acceptance and adoption of the
new technology by energy users must be acquired As it stands the majority of the public is largely unaware
of the development and significance of AP while those who are voice concerns about genetic engineering the
use of toxic materials the use of rare and expensive raw materials and the high societal costs involved in the
development along all technology pathways
612 Situation of the European AP research and technology base
Europersquos scientific communities form more than 60 of the 150 or so research groups on AP worldwide
boasting well-educated researchers and a diverse range of scientists - an interdisciplinary approach being
crucial for scientific advancement within this highly innovative field Together these groups cover all of the
identified existing technological pathways along which the advancement of AP might accelerate thus
increasing the likelihood of cooperation between European scientists with possible breakthroughs on any
given path
Significant improvements are still needed with respect to cost-efficiency lifetimedurability energy efficiency
and resource use for all existing AP technologies and progress is being made in addressing these knowledge
and technology gaps Yet while this technological development making strides along multiple pathways
simultaneously shows a considerable amount of potential the scientific community alone cannot accelerate
the development of the industrial implementation of AP Aiding the development from a currently low
technology readiness level and eventually commercialising AP will involve a host of enabling factors
including those of the financial structural regulatory and social nature
As it stands currently European investment into AP technologies falls short of the amounts being dedicated in
a number of non-European countries and it could be argued is rather short-term if not short-sighted Further
stifling the potential of these technologies is the fact ndash significant considering most European research activity
into AP operates at a national level (only one of the six consortia in Europe being pan-European) ndash that both
national research plans and their funding are fragmented lacking a necessary integrated approach Adding to
this fragmentation there appears to be a lack of cooperation between research groups and academia on the
one hand and between academia and industry on the other This suggests that there are some structural
barriers impeding the speed and success of the development and eventual commercialisation of AP in
Europe
111
Accelerating the development of AP requires bringing the best and brightest to the forefront of the research
being carried out in the field which would in turn involve a conscious effort to boost collaboration of the top
contributors across Europe - such an effort has been the cluster of several FP7 projects the good example of
which may well serve as a foundation on which to build in the future Once the divide between research
groups and academia has been breached and the technological advancement of AP technologies has been
given the push needed to be able to climb higher up the TRL scale interest from and in turn collaboration with
the industry should rise
62 Roadmap overview
The assessment of the existing lsquostate of the artrsquo undertaken for this study reveals that AP technologies are in
general currently at relatively low levels of technology readiness levels91
There are many outstanding gaps in
fundamental knowledge and technology that must be addressed before AP can attain the level of development
necessary for industrial scale implementation Moreover there is not as yet any compelling evidence to
suggest that any particular AP pathway or sub-approach therein can currently be identified as clearly lsquomore
promisingrsquo than another Given this situation it seems appropriate at least for the time being to adopt an
lsquoopenrsquo approach to possible support measures for AP-related research efforts which does not single out and
prioritise any specific AP pathway or sub-approach This conclusion corresponds to the broad consensus view
expressed by participants at the workshop on lsquoArtificial Photosynthesis in Horizon 2020rsquo held in May 2016
Notwithstanding the above assessment if AP is to establish a role in the overall portfolio of energy sources
then the longer-term objective must be to develop competitive and sustainable AP technologies that can be
implemented at an industrial scale Thus a technology development roadmap for AP must support the
transition from fundamental research and laboratory-based validation through to demonstration at a
commercial or near commercial scale and ultimately industrial replication within the market Upscaling of
technologies and integration of processes in a complete lsquovalue chainrsquo ie from light harvesting through to
solar fuel (and other AP-based products) will require greater levels of investment and inevitably will imply
making choices on which technology options to prioritise As the general aim (of the roadmap) is to accelerate
industrial implementation these choices should reflect market opportunities for commercial application of AP
technologies while bearing in mind the overarching policy objectives of increasing the share of renewable
energy sources in overall energy supplies
621 Knowledge and technology development
Following from the above in terms of knowledge and technology development activities the outline roadmap
for support for the development of AP technologies consists of three phases as illustrated in Figure 61 and
described in more detail in the following sub-sections
91
Although the situation of with respect to different process varies most are assessed to be only at TRL 3 or 4 (ie corresponding to lsquoexperimental proof of conceptrsquo or lsquotechnology validated in labrsquo)
112
Figure 61 General development roadmap visualisation
Phase 1 Phase 3Phase 2
Regional MS amp EU
Regional MS EU amp Private
Private amp EU
Private (companies)
FUNDINGSOURCE
TRL 9Industrial
Implementation
TRL 6-8Demonstrator
Projects
Pilot ProjectsTRL 3-6
TRL 1-3Fundamental
Research
RampDampI ACTIVITIES
2017 2025 2035
113
In the following description for convenience the timeline for activities is addressed in three distinct phases It
should be noted however that some AP technologies are more advanced than others and that they
accordingly could already be at or close to readiness for pilot projects (addressed under Phase 2)
Accordingly some laboratory-based validation (TRL 4) and lsquorelevant environmentrsquo validation projects (TRL 5)
may be envisaged within Phase 1 of the Roadmap Conversely as all fundamental knowledge and technology
issues will be not be solved within the 5-7 year time horizon foreseen for Phase 1 the need to support such
development through smaller scale research projects can be expected to continue into Phase 2 of the
Roadmap and possibly beyond
Furthermore in addition to support for fundamental knowledge and technology development the Roadmap
foresees the need to integrate lsquosupporting and accompanying activitiesrsquo (see Section 622) These activities
should run in parallel to the support for knowledge and technology development with initial activities starting
within Phase 1 of the Roadmap and continuing throughout the entire period of the Roadmap It may be
appropriate that some of the suggested activity areas are addressed as part of the proposed Networking
action (Action 2) and Coordinating action (Action 5)
Phase 1 - Time horizon short term (from now to year 5-7)
This phase will target the continuation of early stage research on AP technologies in parallel with initiation of
the process of scaling-up from laboratory based bench-scale projects towards pilot scale projects (ie to
validate whether bench scale projects are viable at a pilot scale) In keeping with the general status of AP
knowledge and technology development the scope of support during this phase should remain lsquoopenrsquo to all
existing (and potential) AP technology pathways and sub-options therein Such an approach should allow for
continued long-term advances in underpinning rsquogenericrsquo scientific knowledge that may lead to a breakthrough
in terms of newnovel approaches for AP while at the same time pushing forward towards addressing
technology challenges across the broad spectrum of AP pathwaysapproaches Notwithstanding this lsquoopenrsquo
approach eventual support may be directed towards specific topics that have been identified as areas where
additional effort is required to address existing knowledge and technology gaps
Under Phase 1 possible EU funding support should a priori be directed towards multiple small scale projects
(eg euro 3-5 million) that can complement existing regional and national programmes (and existing related EU-
level support)
Phase 1 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 1)
Recommendation Support for multiple small AP research projects
Objective To address outstanding gaps in fundamental knowledge and technology relating to AP
Rationale There are many remaining outstanding gaps in AP-relevant fundamental knowledge and
technology that must be addressed before AP systems can attain the level of development
necessary for industrial scale implementation This requires continued efforts dealing with
fundamental knowledge aspects of AP processes together with development of necessary
technology for the application of AP
Resources needed Project funding indicative cost circa euro 3-5 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact Strengthen diversify and accelerate knowledge and technology development for
processesdevices for AP-based production of hydrogen (water splitting) and carbon-based lsquosolar
fuelsrsquo
Priority
High
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
114
Recommendations to support knowledge and technology development (Action 2)
Recommendation Support for enhanced networking for AP research and technology development
Objective To improve information exchange cooperation and collaboration so as to increase efficiency and
accelerate AP-relevant knowledge and technology development towards industrial scale
implementation
Rationale AP research and technology development requires expertise across multiple and diverse
scientific areas both theoretical and applied Notwithstanding existing efforts to support and
enhance European AP research networks (eg AMPEA and precursors) AP research efforts in
the EU are fragmented being to a large extent organised and funded at national levels Further
development of EU-wide (and globally integrated) network(s) would promote coordination and
cooperation of research efforts within the AP field and in related fields addressing scientific
issues of common interest This action ndash offering secure funding for networking activities at a
pan-European level ndash should raise collaboration and increase synergies that potentially are being
currently overlooked
The broader international dimension of AP research and technology development could also be
addressed under this action In particular to develop instruments to facilitate research
partnerships beyond the EU (eg with US Japan Canada etc)
Resources needed Network funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact By providing a platform for knowledge exchange the speed of discovery and exploitation of
knowledge and technology developments should be accelerated both within the research
community and with industry
Priority
Medium
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
Recommendations to support knowledge and technology development (Action 3)
Recommendation AP Inducement Prize
Objective To provide additional stimulus for research technology development and innovation in the field
of AP while also raising awareness amongst the public and other stakeholders
Rationale The inducement prize would a priori target ldquoproof of conceptrdquo of AP at a bench-scale that meet
eligibility and award criteria set for the prize Experience suggests that lsquoinducement prizersquo
schemes can be particularly effective in situations corresponding to those of AP (ie where there
are a number of competing emergent technologies in the TRL 2-4 range that can potentially
deliver similar outcomes) The prize should provide an incentive for researchers to accelerate AP
RampD efforts and also potentially extend interest beyond the current AP research base to a wider
range of potential researchersinnovators
Resources needed Financial prize circa euro3 million
Prize organisation etc euro03 million
Actors involved Funding sources EU possible national (MS) contribution
Potential prize recipients Research and technology development institutions and (possibly)
industry
Expected impact Increased research intensity and wider participation resulting in turn to sooner than otherwise
demonstration of bench-scale AP devices This should provide for an earlier transition from
laboratory based research towards pilot projects
Priority
Medium
Suggested date of implementation92
Short (Phase 1)
92
Based on views gathered by the study there appears to be a general consensus that 3-4 years could be sufficient for the inducement prize contest timeframe Extending the timeframe for a longer period risks prize fatigue where contestants lose sight of the original prize aim and interest can start to wane
115
Phase 1 - Milestones
The scope of knowledge and technology development activities envisaged under Phase 1 is potentially very
broad as it covers multiple lsquopathwaysrsquo and a wide array of challengesissues ranging from general to highly
specific These concern each of the main AP steps (eg light harvesting charge separation water splitting
and fuel production) and range from materials issues device design and supporting activities such as process
modelling In general terms key criteria for evaluating overall progress towards the ultimate objective of
commercial implementation will revolve around factors such as efficiency of conversion of light into solar fuels
alongside the durability and potential cost-effectiveness of AP systems Shorter-term targets (lsquomilestonesrsquo)
could be set for minimum performance levels in terms of conversion efficiency (eg 10 conversion of solar
energy to hydrogen or to carbon-based fuels) although given the variation in progress across AP pathways
variable efficiency targets for individual pathways would seem appropriate
However if the purpose of the milestone is to mark the point of transition from Phase 1 to Phase 2 of the
Roadmap then a pragmatic milestone may be defined in terms of the development of an AP devicesystem
able to produce a lsquouseablersquo quantity of solar fuel in laboratory conditions sufficient to warrant further
development towards a pilot projectplant (Phase 2) In this regard it may make sense to a greater or lesser
degree to align the milestones for Phase 1 to the award criteria retained for the proposed inducement prize
Phase 2 - Time horizon medium term (from year 5-7 to year 10-12)
This phase will focus on reinforcing the implementation of pilot scale projects while initiating the process of
scaling up to a demonstration scale The scope of eventual support should focus on a limited number of
projects for the most promising AP technologies in order to demonstrate their viability at a pilot scale In this
context public (EU) funding support should be directed towards a limited number of medium scale projects At
the same time there should be encouragement of private sector participation in technology development
projects
Phase 2 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 4)
Recommendation Support for AP pilot projects
Objective To develop AP devices and integrated systems moving from laboratory scale up to an
(industrial) relevant scale of production This should enable comparative assessment of different
AP technology approaches at a production scale permitting industrial actors to make a
meaningful assessment of their potential viability for commercial deployment Equally these
projects should serve to identify (priority) areas where additional knowledge and technology
development is required in order to achieve industrial scale implementation
Rationale To reach industrial implementation of AP the feasibility of upscaling from laboratory conditions to
those approaching actual operational conditions needs to be demonstrated Accordingly pilot
projects under this Action item should provide for the testing and evaluation of AP devices to
assess and demonstrate the feasibility of reaching necessary characteristics (eg efficiency
levelstargets durabilitylife-cycle cost effectiveness) for commercial application for the
production of solar fuels The implementation of flexible pilot plants with open access to
researchers and companies should support (accelerated) development of manufacturing
capabilities for AP devices and scaling-up of AP production processes and product supply
Resources needed Project funding indicative cost circa euro 5-10 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Strengthen and accelerate knowledge and technology development for processesdevices for
AP-based production of hydrogen (water splitting) and carbon-based lsquosolar fuelsrsquo
Priority
High
Suggested date of implementation
Medium (Phase 2)
116
Recommendations to support knowledge and technology development (Action 5)
Recommendation Support for AP coordination
Objective To enhance efficiency (and effectiveness) of AP research efforts and more broadly to raise
coordination in the fields of solar fuels and energy technology development
Rationale There is a general need to ensure that research budgets are used effectively and to avoid
duplication of research effort In the context of AP there is a need to identify lsquomost promisingrsquo
technologies and set common priorities accordingly Moving to a common European AP
technology development strategy will require inter alia alignment of national research efforts in
the EU and (possible) cooperation at a broader international level Equally with the aim of
accelerating industrial implementation of AP there is a need to ensure cooperation and
coordination between research and technology development activities among the lsquoresearch
communityrsquo and industry
Resources needed Networkcoordination funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Improved coordination of AP research activities at European level (and possibly international
level) and improved priority setting to address knowledge and technology gaps for AP-based
processes and products
Priority
High
Suggested date of implementation
Medium (Phase 2) with possibility to extend implementation over
long term
Phase 2 - Milestones
The purpose of the AP pilot projects proposed under Phase 2 is inter alia to develop AP production
devicessystems operating at a sufficient scale to assess their potential viability for commercial deployment
Thus AP devicessystems developed within the pilot projects should attain sufficient performance levels and
fulfil basic operational and other characteristics (eg conversion efficiency lifetimedurability
sustainabilityresource use and cost-effectiveness) that are sufficient to attract the potential interest of private
sector (industry) investors Specific milestones for AP pilot projects may therefore be set in terms of multiple
target technical performance requirements but the overarching target lsquomilestonersquo for pilot projects will relate to
the overall assessment of their potential economic (commercial) viability conditional on further technological
developments (including engineering) and subject to their potential to comply with sustainability and other
social requirements
As a bottom line in terms of marking the point of transition from Phase 2 to Phase 3 of the Roadmap the test
for a lsquosuccessfulrsquo pilot project will be reflected in developing technology solutions able to attract private
investors willing to commit to their next stage of development either through a demonstration project (Phase
3) or directly to industrial implementation (lsquoearlyrsquo commercial projects)
Phase 3 - Time horizon long term (from year 10-12 to year 15-17)
This phase will focus of the development of ndash one or more ndash demonstration projects to assess the viability of
AP technologies at an industrial scale and facilitating the transfer of AP-based production systems from
demonstration stage into industrial production for lsquofirstrsquo markets The scope of eventual support should focus
on the AP technologies identified as most viable for commercialindustrial application However demonstration
level products should be led by the private sector ndash reflecting the need to assess commercial viability of
technologies ndash with co-funding provided by the public sector ndash reflecting the risk and large financial burden of
investments in such projects
117
Phase 3 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 6)
Recommendation Support for AP demonstrator projects
Objective To develop one or more demonstrator projects to assess the viability of AP technologies at a
close-to industrial scale (ie the project should be of a sufficient size to serve as a platform and
facilitating the transfer of AP-based production systems from demonstration stage into industrial
production for lsquofirstrsquo markets)
Rationale The demonstration project(s) provide a lsquostepping stonersquo between pilot projects and industrial
implementation The projects should not only provide validation of AP devices and systems but
also allow for developing and evaluating the integration of the full AP value chain93
By
demonstration the (commercial) viability of AP the project(s) should promote full industrial
investments that might otherwise be discouraged by the high cost and risk94
At the same time
beyond addressing technological and operational issues the demonstration projects should
address all other aspects ndash eg societalpolitical environmentalsustainability
economiccommercialfinancial legalregulatory geographic etc ndash necessary to evaluate how
AP based production of solar fuels could be implemented in practice
Resources needed To be determined
[Indicative budget envelope circa euro10-20 million per individual project However required funding
will depend on size and ambition of the project and may significantly exceed this amount]
Actors involved Funding sources Industry with EU support
Funding recipients Research and technology development institutions industry
Expected impact The projects should both build investor confidence in the commercial application of AP-based
solar fuel technologies and raise public confidence including in terms of safety and reliability
Priority
Medium
Suggested date of implementation
Long (Phase 3)
Phase 3 - Milestones
Given that the primary purpose of the demonstrator projects is to assess the viability of AP technologies at a
close-to industrial scale an initial milestone for such projects would be for the plants to be operational and to
be able to produce solar fuels in commercially significant volumes Ultimately the target lsquomilestonersquo will be to
produce solar fuels that are cost-competitive under actual market conditions and commercial requirements
while complying with other key requirements (eg safety societal acceptance etc)
622 Supporting and accompanying activities
The technological development of AP will throughout its various phases be guided by regulatory and market
measures as well as the degree of social acceptance In order to help secure favourable conditions for the
development and eventual commercialisation of AP technologies support will need to be provided from a very
early stage onwards within both of these spheres The prices of competing fuels and carbon emissions may
need to be regulated as well as incentives affecting the demand for renewable energy sources introduced
while the breadth of technological development regarding AP should not be hindered by regulation within the
current phase of research nor research into an eventual shift to a lsquohydrogen economyrsquo be put on the back
burner Thorough involvement of all societal actors in education and open debate regarding the potential
benefits and drawbacks of AP technologies as well as barriers to social acceptance and issues raising public
concern is also required At the same time the economic and commercial aspects of AP production
technologies and AP-produced solar fuels need to be understood including in terms of the development of
successful business models and the competitiveness of European industry in the field of AP and renewable
energy more generally
93
Where this covers the whole AP supplyvalue chain from upstream supply (eg materials components etc) to downstream demand (markets)
94 For example high cost resulting from accelerated investments to scale-up to industrial scale and high-risk profile resulting from uncertainty over which AP technologies may prove most successful together with uncertainty over operating costs and future market prices and demand for solar fuels etc These factors may otherwise discourage investments in (initial) full scale projects unless some public support is provided
118
There is potentially a wide range of themes ndash beyond purely technological and operational aspects ndash which
require to be better understood and which may be addressed through supporting and accompanying activities
including the following (non-exhaustive) topics
Industry engagement and technology transfer As far as can be ascertained the engagement of
industry in the field of AP technologies has to date been limited although because of its commercial
sensitivity it is difficult to obtain a clear picture of industrycompaniesrsquo interest in AP Nonetheless there is
a general view that a greater engagement of the industry would be beneficial for the development of AP
technologies and will become increasingly important as technologies reach higher TRLs and move closer
to commercial implementation An active involvement of industrial players in cooperative research projects
could facilitate the transfer of technology from the research community to industry (or vice versa) thereby
helping speed up the evolution from research prototypes and pilots to commercial implementation
Intellectual property protection To ensure future development and industrial application European
intellectual property in the area of AP should be adequately protected through patents At the same time
worldwide developments in AP-related patent-protected technologies should be taken into consideration
to ensure that Europe avoids potentially damaging dependences on non-European technologies
Regulatory conditions and support measures As a minimum AP technologies and products entering
the market should face a legal and regulatory environment that does not discriminate against their use and
provides a level playing field compared to other energyfuel types Beyond this there may be a public
policy justification (eg reflecting positive externalities of AP) for creating a specifically favourable
regulatory and legal framework to encourage the take-up and diffusion of AP technologies and products
At the same time other actions for example AP project financing support may be implemented to support
the industryrsquos AP investments these may be both for production investments but also for downstream
users faced by high switching costs (eg from fossil to solar fuels)
Societal aspects and safety AP technologies may potentially raise a number of public concerns that
need to be understood and addressed These may relate to safety aspects of the production storage
distribution and consumption of AP-based products for example there may be concern over the use of
genetically modified organisms (GMOs) in synthetichybrid AP processes Other areas of concern may
arise for example in relation to land use requirements or use of rare materials etc In general both
among the general public and even within the industry there is limited knowledge of AP Accordingly it
may be appropriatenecessary to implement activities to raise public and industry awareness of AP
Market potential relating to the assessment of the potential role and integration of AP energy supply and
demand Here multiple scenarios are possible for example depending on whether advances in AP
technology are targeted towards production of hydrocarbons or of hydrogen The former would require
fewer changes in terms of supporting infrastructure development (eg for fuel storage and distribution) but
is currently lagging behind in terms of AP technological development For the latter future market potential
will depend on the evolution towards a greater adoption of hydrogen-based fuel technologies Better
understanding of the shape and direction of market developments both within the EU and globally will be
important for assessing which AP technology developments offer the best prospects for future industrial
implementation At the same time the sensitivity of future prospects for AP technologies and products to
developments in the costs and market prices of competing (fossil and renewable) fuels should be
assessed
Industry organisation and business development relating to the assessment of future industrial
organisation of AP-technology production including the full supplyvalue chain for solar fuels (ie from
upstream supply of materials components equipment etc through fuel production to downstream market
supply including storage and distribution) Such an assessment will be required to better understand the
potential position and opportunities for the European industry in the area of AP which should also take
account of the business models and strategies for European players within the market
119
The aforementioned topics illustrate the diversity of the dimensions surrounding AP that require to be better
understood In a first instance more detailed economic legalregulatory social and other analyses of these
topics is warranted In turn this may lead to the formulation of more concrete policies and actions to develop
appropriate regulatory frameworks and to shape other market and business conditions in order to ensure a
supportive environment for the development and implementation of AP technologies and products
121
7 References
(1) Wilker M B Shinopoulos K E Brown K A Mulder D W King P W Dukovic G Journal of the
American Chemical Society 2014 136 4316
(2) Tachibana Y Vayssieres L Durrant J R Nature Photonics 2012 6 511
(3) Agency I E 2015
(4) Maeda K Domen K The Journal of Physical Chemistry Letters 2010 1 2655
(5) Ni M Leung M K Leung D Y International Journal of Hydrogen Energy 2008 33 2337
(6) Utschig L M Soltau S R Tiede D M Curr Opin Chem Biol 2015 25 1
(7) Chen L Chen F Xia C Energy amp Environmental Science 2014 7 4018
(8) Carmo M Fritz D L Mergel J Stolten D International Journal of Hydrogen Energy 2013 38 4901
(9) Fukuzumi S Curr Opin Chem Biol 2015 25 18
(10) Pinaud B A Benck J D Seitz L C Forman A J Chen Z Deutsch T G James B D Baum
K N Baum G N Ardo S Energy amp Environmental Science 2013 6 1983
(11) Ursua A Gandia L M Sanchis P Proceedings of the IEEE 2012 100 410
(12) Nelson D L Lehninger A L Cox M M Lehninger principles of biochemistry Macmillan 2008
(13) Alberts B Johnson A Lewis J Raff M Roberts K Walter P Classic textbook now in its 5th
Edition 2010
(14) Magnuson A Anderlund M Johansson O Lindblad P Lomoth R Polivka T Ott S Stensjouml K
Styring S Sundstroumlm V Hammarstroumlm L Accounts of Chemical Research 2009 42 1899
(15) Smolentsev G Sundstroumlm V Coordination Chemistry Reviews 2015 304 117
(16) Hammarstrom L Hammes-Schiffer S Accounts of chemical research 2009 42 1859
(17) Barber J Chemical Society Reviews 2009 38 185
(18) Gust D Moore T A Moore A L Faraday discussions 2012 155 9
(19) Centi G Perathoner S ChemSusChem 2010 3 195
(20) Hansen J Ruedy R Sato M Lo K Reviews of Geophysics 2010 48
(21) Pearson P N Palmer M R Nature 2000 406 695
(22) Faunce T A Lubitz W Rutherford A B MacFarlane D Moore G F Yang P Nocera D G
Moore T A Gregory D H Fukuzumi S Energy amp Environmental Science 2013 6 695
(23) Gorka M Schartner J van der Est A Rogner M Golbeck J H Biochemistry 2014 53 2295
(24) Gust D Moore T A Moore A L Accounts of chemical research 2009 42 1890
(25) Armaroli N Balzani V Angew Chem Int Ed Engl 2007 46 52
(26) House R L Iha N Y M Coppo R L Alibabaei L Sherman B D Kang P Brennaman M K
Hoertz P G Meyer T J Journal of Photochemistry and Photobiology C Photochemistry Reviews 2015 25 32
(27) Utschig L M Silver S C Mulfort K L Tiede D M Journal of the American Chemical Society 2011
133 16334
(28) Listorti A Durrant J Barber J Nature materials 2009 8 929
(29) Styring S Faraday discussions 2012 155 357
(30) Walter M G Warren E L McKone J R Boettcher S W Mi Q Santori E A Lewis N S
Chemical reviews 2010 110 6446
(31) Lewis N S Science 2016 351 aad1920
(32) Concepcion J J House R L Papanikolas J M Meyer T J Proceedings of the National Academy
of Sciences 2012 109 15560
(33) Barber J Tran P D Journal of The Royal Society Interface 2013 10 20120984
(34) Gersten S W Samuels G J Meyer T J Journal of the American Chemical Society 1982 104
4029
(35) Gust D Moore T A Moore A L Accounts of Chemical Research 2001 34 40
(36) Kalyanasundaram K Graetzel M Current opinion in Biotechnology 2010 21 298
(37) Wen F Li C Accounts of chemical research 2013 46 2355
(38) McCrory C C Jung S Ferrer I M Chatman S M Peters J C Jaramillo T F Journal of the
American Chemical Society 2015 137 4347
(39) Alenazey F Alyousef Y Almisned O Almutairi G Ghouse M Montinaro D Ghigliazza F
International Journal of Hydrogen Energy 2015 40 10274
(40) Asthana S Samanta C Bhaumik A Banerjee B Voolapalli R K Saha B Journal of Catalysis
2016 334 89
(41) Ihara M Nishihara H Yoon K S Lenz O Friedrich B Nakamoto H Kojima K Honma D
Kamachi T Okura I Photochemistry and photobiology 2006 82 676
122
(42) Ihara M Nakamoto H Kamachi T Okura I Maedal M Photochemistry and photobiology 2006 82
1677
(43) Fukuzumi S Yamada Y Suenobu T Ohkubo K Kotani H Energy amp Environmental Science 2011
4 2754
(44) Vignais P M Billoud B Meyer J FEMS microbiology reviews 2001 25 455
(45) Utschig L M Dimitrijevic N M Poluektov O G Chemerisov S D Mulfort K L Tiede D M The
Journal of Physical Chemistry Letters 2011 2 236
(46) Prince R C Kheshgi H S Critical reviews in microbiology 2005 31 19
(47) Brown K A Wilker M B Boehm M Dukovic G King P W Journal of the American Chemical
Society 2012 134 5627
(48) Lubner C E Applegate A M Knoumlrzer P Ganago A Bryant D A Happe T Golbeck J H
Proceedings of the National Academy of Sciences 2011 108 20988
(49) Iwuchukwu I J Vaughn M Myers N ONeill H Frymier P Bruce B D Nature nanotechnology
2010 5 73
(50) Yacoby I Pochekailov S Toporik H Ghirardi M L King P W Zhang S Proceedings of the
National Academy of Sciences 2011 108 9396
(51) Silver S C Niklas J Du P Poluektov O G Tiede D M Utschig L M Journal of the American
Chemical Society 2013 135 13246
(52) Grimme R A Lubner C E Bryant D A Golbeck J H Journal of the American Chemical Society
2008 130 6308
(53) Rumpel S Siebel J F Faregraves C Duan J Reijerse E Happe T Lubitz W Winkler M Energy amp
Environmental Science 2014 7 3296
(54) Volgusheva A Styring S Mamedov F Proceedings of the National Academy of Sciences 2013 110
7223
(55) Rozendal R A Jeremiasse A W Hamelers H V Buisman C J Environmental Science amp
Technology 2007 42 629
(56) Clauwaert P Toledo R Ha D v d Crab R Verstraete W Hu H Udert K Rabaey K Water
Science and Technology 2008 57 575
(57) Bajracharya S ter Heijne A Benetton X D Vanbroekhoven K Buisman C J Strik D P Pant
D Bioresource technology 2015 195 14
(58) Li M Canniffe D P Jackson P J Davison P A FitzGerald S Dickman M J Burgess J G
Hunter C N Huang W E The ISME journal 2012 6 875
(59) Zhang D Zhao Y He Y Wang Y Zhao Y Zheng Y Wei X Zhang L Li Y Jin T ACS
synthetic biology 2012 1 274
(60) Blankenship R E Tiede D M Barber J Brudvig G W Fleming G Ghirardi M Gunner M
Junge W Kramer D M Melis A science 2011 332 805
(61) Fujishima A Honda K Nature 1972 238 37
(62) James B D Baum G N Perez J Baum K N Square O V DOE report 2009
(63) Hanna M Nozik A Journal of Applied Physics 2006 100 074510
(64) Ross R T Hsiao T L Journal of Applied Physics 1977 48 4783
(65) Khaselev O Turner J A Science 1998 280 425
(66) Wang X Maeda K Chen X Takanabe K Domen K Hou Y Fu X Antonietti M Journal of the
American Chemical Society 2009 131 1680
(67) Kanan M W Nocera D G Science 2008 321 1072
(68) Brillet J Yum J-H Cornuz M Hisatomi T Solarska R Augustynski J Graetzel M Sivula K
Nature Photonics 2012 6 824
(69) Kim J H Kaneko H Minegishi T Kubota J Domen K Lee J S ChemSusChem 2016 9 61
(70) Gao L Cui Y Wang J Cavalli A Standing A Vu T T Verheijen M A Haverkort J E
Bakkers E P Notten P H Nano letters 2014 14 3715
(71) Standing A Assali S Gao L Verheijen M A van Dam D Cui Y Notten P H Haverkort J E
Bakkers E P Nature communications 2015 6
(72) Gao L Cui Y Vervuurt R H van Dam D van Veldhoven R P Hofmann J P Bol A A
Haverkort J E Notten P H Bakkers E P Advanced Functional Materials 2015
(73) Smolyakov G A Osinski M A Google Patents 2011
(74) Herrera A S Google Patents 2013
(75) Joo O S Jung K D Min B K Kim S H Oh J W Google Patents 2008
(76) Google Patents 2015
(77) Liu J Zhang Y Lu L Wu G Chen W Chemical Communications 2012 48 8826
(78) Li J Wu N Catalysis Science amp Technology 2015 5 1360
(79) Laguna-Bercero M A Journal of Power Sources 2012 203 4
123
(80) Graves C Ebbesen S D Mogensen M Solid State Ionics 2011 192 398
(81) Li W Wang H Shi Y Cai N International journal of hydrogen energy 2013 38 11104
(82) Fu Q Mabilat C Zahid M Brisse A Gautier L Energy amp Environmental Science 2010 3 1382
(83) Graves C Ebbesen S D Mogensen M Lackner K S Renewable and Sustainable Energy Reviews
2011 15 1
(84) Christopher K Dimitrios R Energy amp Environmental Science 2012 5 6640
(85) Sun X Chen M Jensen S H Ebbesen S D Graves C Mogensen M international journal of
hydrogen energy 2012 37 17101
(86) Ivy J Summary of electrolytic hydrogen production milestone completion report National Renewable
Energy Lab Golden CO (US) 2004
(87) Haering C Roosen A Schichl H Schnoumlller M Solid State Ionics 2005 176 261
(88) Mahmood A Bano S Yu J H Lee K-H Energy 2015 90 Part 1 344
(89) Jakobsson N B FRIIS P C BOslashGILD H J Google Patents 2014
(90) Stoots C M OBrien J E Herring J S Lessing P A Hawkes G L Hartvigsen J J Google
Patents 2011
(91) JABBAR M HOslashGH J Stamate E BONANOS N Google Patents 2013
[Ca
talo
gu
e n
um
be
r]
KI-N
A-2
7-9
87-E
N-N
KI-N
A-2
7-9
87-E
N-N
5
Abstract
Technologies based on Artificial Photosynthesis (AP) offer the potential to deliver sustainable ldquosolarrdquo
alternatives to fossil fuels which are storable and transportable and can thus respond to the problem of
intermittency of other solar wind and marine energy technologies AP research has intensified over the last
decade pursuing multiple approaches or ldquopathwaysrdquo that each have their own relative advantages and
challenges However as most AP technologies are still at a low level of technology readiness it is currently
not possible to identify those AP pathways and specific technologies offering the greatest promise for future
industrial implementation The study argues accordingly that possible public support should retain an
approach that for the time being keeps Europersquos AP options open The proposed roadmap for support for AP
technology development which could be supported under Horizon 2020 foresees actions to address current
gaps in scientific knowledge and technology capabilities while scaling-up the size of projects through the
implementation of pilot projects and demonstrator projects that can validate the viability of AP technologies at
a commercial scale Europe occupies a frontline position in AP research with 60 of the estimated 150
leading global research groups located in Europe However AP research in Europe is relatively less well-
funded than elsewhere notably in the US and Japan European research efforts are also fragmented driven
by national-level strategies and research programmes Therefore the proposed roadmap integrates actions to
support improved networking and cooperation within Europe and possibly at a wider international-level In
turn improved coordination of national research efforts could be achieved through the elaboration of a
common European AP technology strategy aimed at positioning European industry as a leader in the AP
technology field
7
Executive Summary
Objectives and methodology
Artificial photosynthesis (AP) is considered among the most promising new technologies able to deliver
sustainable alternatives to current fuel supplies often viewed as a potential ldquogame changerrdquo in the fields of
energy conversion and energy production AP can be used to produce hydrogen or carbon-based fuels ndash
collectively referred to as ldquosolar fuelsrdquo ndash that offer an efficient and transportable store of (solar) energy which
can be used as an alternative to fossil fuels and as a feedstock for a wide range of industrial processes
Set against the above background the purpose of this study is to provide a full assessment of the situation of
AP providing answers to the questions Who are the main European and global actors in the field What is
the ldquostate of the artrdquo and what are the main ldquobottlenecksrdquo in scientific and technological development What
are the key economic and technological parameters to accelerate industrial implementation Answers to the
questions provide in turn the basis for formulating recommendations on the pathways to follow and the action
to take to maximise the eventual market penetration and exploitation of AP technologies
To gather information on the direction capacities and challenges of ongoing AP development activities the
study has conducted a comprehensive review of scientific and other literature and implemented a survey of
academics and industrial players This information together with the findings from a series of in-depth
interviews provides the basis for a multi-criteria analysis to identify key bottlenecks for the main AP
technology pathways The study findings were validated at a participatory workshop of leading European AP
researchers which also identified scenarios and sketched out roadmaps for actions to support the future
development of AP technologies over the short to long term
Definition of Artificial Photosynthesis
For the purposes of this study artificial photosynthesis is understood to be a process that aims to mimic
the physical chemistry of natural photosynthesis by absorbing solar energy in the form of photons and
using this energy to generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
Main technology pathways for artificial photosynthesis
It is difficult to precisely define the parameters of AP but there are three main identifiable technology pathways
along which research and development is now advancing
Synthetic biology amp hybrid systems aim to mimic existing biological systems that perform different stages of
photosynthesis (ie light-harvesting charge separation or molecule synthesis) and combine them to produce
specific fuel molecules These technologies are at a very early stage (TRL 1-4) however researchers have
already produced small quantities of hydrogen through the water-splitting reaction and have demonstrated the
reduction of carbon dioxide to methane and acetate Research is also investigating the possibility of using
basic cells (biological) to host biological machinery to generate more complex fuel molecules The long-term
goal is to reliably generate large quantities of fuel molecules combining and converting simple starting
compounds such as H2 and CO2 into a series of different compounds using enzymes and synthetic organic
and inorganic catalysts
8
Photoelectrocatalysis combines and integrates photovoltaic (PV) technologies ndash ie semiconductor materials
able to generate electric current from sunlight ndash with water electrolysis in a photoelectrochemical cell (PEC) or
suspensions of photoactive nanoparticles thereby enabling solar energy to be used to produce hydrogen (and
oxygen) via a water-splitting reaction PV technologies are already deployed commercially and are producing
power on a megawatt scale (TRL 7-8) however PECs to perform photoelectrocatalysis are as yet at a
relatively low stage of development (TRL 2-4) The main challenges facing this technology involve developing
materials that have high solar-to-hydrogen (STH) efficiencies are cheap to manufacture (eg use earth-
abundant metals) and are stable for long periods of time
Co-electrolysis uses co-electrolysis of carbon dioxide and water to generate syngas (COH2) by
simultaneously reducing carbon dioxide and water using a high temperature solid oxide cell electrolyser
(SOEC) syngas can then be used to generate simple intermediate compounds that can be used as feedstock
for more complicated chemicals Water electrolysers ndash such as alkaline and polymer electrolyte membrane
(PEM) electrolysers ndash used to convert water into H2 and O2 are mature technologies (TRL 7-8) that have
been commercialised SOECs are at a lower level of development (TRL 3-5) and given their high electricity
requirements current research is focused on increasing their efficiency
Technology pathways for artificial photosynthesis and indicative selection of generated compounds
Source University of Sheffield (PV = Photovoltaics)
AP research in Europe
Research in the AP field ndash bringing together interdisciplinary expertise from biology biochemistry biophysics
and physical chemistry ndash has intensified over the last decade Today more than 150 research groups are
estimated to be active worldwide of which 60 are in Europe1 Interest from industry is growing as well
although it remains limited due to the overall low levels of readiness for commercial application of many AP
technologies
Europe has a diverse community of researchers active in the AP field and covering all the main pathways with
the largest numbers of research groups located in Germany the Netherlands Sweden and the UK The most
significant and only truly pan-European-level research network is AMPEA2 but most networks and consortia
are national Some Member States have set up their own AP research programmes roadmaps and funds and
1 Source study estimates
2 Advance Materials and Processes for Energy Application (AMPEA) which is one of the joint programmes of the Europe nargy Research
alliance (EERA)
9
there has been successful collaboration in several ongoing European-funded FP7 projects Overall however
the level of funding in Europe falls short of that available elsewhere and national research plans (and funding)
seem fragmented and scattered with a short-term focus and lacking an integrated approach with common
research goals and objectives Equally the level of collaboration between academia and industry seems to be
more limited in Europe compared for example to the US or Japan
Relatively few companies are active in the field of AP and they can be counted in the lsquotensrsquo rather than
lsquohundredsrsquo Co-electrolysis is the only area where AP-related technologies are currently commercially viable
while current industry research activities mostly concern photoelectrocatalysis where companies from various
sectors (eg ranging from automotive and electronics to chemicals and oil refining) are involved There is
some industry involvement in synthetic biology amp hybrid systems but it is limited reflecting the early stage of
research activities along this pathway
Main challenges to development and implementation of AP technologies
To form a sustainable and cost-effective part of future European and global energy systems and a source of
high-value and low carbon feedstock chemicals the development of AP technologies must address certain
fundamental requirements
Efficiency in each main step of AP light captureharvesting (eg maximising the percentage of the
spectrum that can be utilised) energy transfer to a reaction centre (eg minimising energy loss during the
transfer) and charge generation and separation to allow the desired chemical reaction to take place (eg
preventing charge recombination)
Durability of the system in terms of the amount of energy that can be produced during the lifetime of an AP
system which is a challenge because of the rapid degradation of some materials under AP system
conditions (eg lack of long-term stability in aqueous conditions or when exposed to sunlight)
Sustainability of material use eg minimising the use of rare and expensive raw materials
To meet these requirements the main AP technology pathways must overcome several gaps in fundamental
knowledge and technology development (see tables) Even if these gaps can be addressed and the feasibility
of commercial- and industrial-scale deployment of AP systems can be demonstrated at a cost level that
enables AP-based products to be competitive in the market place commercial implementation may raise other
practical concerns These may arise in relation to land use water availability and possible environmental or
social concerns which have not yet been fully explored
Synthetic biology amp hybrid systems
Knowledge gaps Technology gaps
Develop molecular and synthetic biology tools to enable
the engineering of efficient metabolic processes within
microorganisms
Improve metabolic and genetic engineering of
microorganism strains
Improve metabolic engineering of strains to facilitate the
production of a large variety of chemicals polymers and
fuels
Enhance (product) inhibitor tolerance of strains
Minimise losses due to chemical side reactions (ie
competing pathways)
Develop efficient mechanisms and systems to separate
collect and purify products
Improve stability of proteins and enzymes and reduce
degradation
Develop biocompatible catalyst systems not toxic to
micro-organisms
Optimise operating conditions and improve operation
stability (from present about gt100 hours)
Mitigate bio-toxicity and enhance inhibitor tolerance at
systems level
Improve product separation at systems level
Improve photobioreactor designs and up-scaling of
photobioreactors
Integrate enzymes into the hydrogen evolving part of
ldquobionic leafrdquo devices
Improve ldquobionic leafrdquo device designs
Up-scale ldquobionic leafrdquo devices
Improve light energy conversion efficiency (to gt10)
Reduce costs of the production of formic acids and other
chemicals polymers and fuels
10
Photoelectrocatalysis
Knowledge gaps Technology gaps
Increase absorber efficiencies
Increase understanding of surface chemistry at
electrolyte-absorber interfaces incl charge transfer
dynamics at SCdyecatalyst interfaces
Develop novel sensitizer assemblies with long-lived
charge-separated states to enhance quantum
efficiencies
Improve charge transfer from solid to liquid
Increase stability of catalysts in aqueous solutions
develop self-repair catalysts
Develop catalysts with low over-potentials
Reduce required rare and expensive catalysts by core-
shell catalyst nanoparticles with a core of an earth-
abundant material
Develop novel water-oxidation catalysts eg based on
cobalt- and iron oxyhydroxide-based materials
Develop efficient tandem absorber structures on (widely
available and cheaper) Si substrates
Develop nanostructure configurations promising
advantages with respect to materials use optoelectronic
properties and enhanced reactive surface area
Reduce charge carrier losses at interfaces
Reduce catalyst and substrate material costs
Reduce costs for tandem absorbers using silicon-based
structures
Develop concentrator configurations for III-V based
tandem absorber structures
Scale up deposition techniques and device design and
engineering
Improve device stability towards long-term stability goal
of gt1000 hours
Improve the STH production efficiencies (to gt10 for
low-cost material devices)
Reduce costs towards a hydrogen production price of 4
US$ per kg
Co-electrolysis
Knowledge gaps Technology gaps
Basic understanding of reaction mechanisms in co-
electrolysis of H2O (steam) and CO2
Basic understanding of the dynamics of
adsorptiondesorption of gases on electrodes and gas
transfer during co-electrolysis
Basic understanding of material compositions
microstructure and operational conditions
Develop new improved materials for electrolytes and
electrodes
Avoid mechanical damages (eg delamination of
oxygen electrode) at electrolyte-electrode interface
Reduce carbon (C) formation during co-electrolysis
Optimise operation temperature initial fuel composition
and operational voltage to adjust H2CO ratio of the
syngas
Replace metallic based electrodes by pure oxides
Improve long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O
(steam) and CO2
Improved stability performance (from present ~50 hours
towards the long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel
composition and operational voltage to adjust H2CO
ratio of the syngas
Improvement of co-electrolysis syngas production
efficiencies towards values facilitating the production of
competitive synthetic fuels via FT-processes
Cost reduction towards competitiveness of synthetic
fuels with fossil fuels
The AP technology development roadmap
Although AP technologies show great potential and despite significant progress made in recent years there is
still a significant way to go before they are ready for industrial implementation Although some aspects of AP-
based systems are well developed the assessment of the existing lsquostate of the artrsquo shows that AP
technologies are generally at low levels of technology readiness (eg TRL 3-4) Moreover there is not yet
compelling evidence to suggest any AP pathway (or sub-approach therein) is ldquomore promisingrdquo than another
This being the case it seems appropriate to adopt an ldquoopenrdquo approach to possible support measures for AP-
related research efforts in the near term which does not single out and prioritise any specific AP pathway or
approach
Nonetheless if AP technologies are to fulfil their potential it will be necessary to achieve the transition from
fundamental research- and laboratory-based validation to demonstration at commercial of near-commercial
scales this ambition forms the long-term goal for the proposed AP technology development roadmap
11
The roadmap distinguishes 3 phases (see figure below) and corresponding recommendations for specific
actions
Phase 1 (short term) Early stage research and scaling-up to pilot projects
Action 1 Support for multiple small AP research projects to address existing knowledge and technology gaps and to
promote long-term advances in scientific knowledge that may contribute to breakthroughs in novel
approaches for AP and to address technology challenges across the board of current (and potential) AP
pathways and approaches
Action 2 Support for enhanced networking of AP research and technology development to reduce fragmentation and
promote coordination and cooperation of research efforts in the AP and related fields through the support for
pan-European networking activities and promotion of research synergies
Action 3 Inducement prize to provide additional stimulus for research technology development and innovation
through a (financial) prize targeting ldquoproof of conceptrdquo of significant advances in the AP field
Phase 2 (medium term) Pilot project implementation and scaling-up to demonstrator projects
Action 4 Support for AP pilot projects to demonstrate the viability of AP concepts through support for a (limited)
number of pilot plant scale projects of the ldquomost promisingrdquo AP technologies
Action 5 Support for AP coordination to ensure effective use of research budgets and to avoid duplication of research
efforts Moving to a common European AP technology strategy requires inter alia alignment of national
research efforts and cooperation at a broader international level Equally to accelerate industrial
implementation cooperation and coordination of activities among the lsquoresearch communityrsquo and industry
should be promoted
Phase 3 (long term) Demonstrator project implementation
Action 6 Support for AP demonstrator projects to demonstrate the viability of AP technologies through support for one
or more demonstrator projects that facilitate the transfer of AP production systems to industrial production for
ldquofirstrdquo markets while allowing an evaluation of the development and integration of the full AP value chain (ie
from upstream supply of materials and components to downstream markets for AP-based products) The
demonstrator project(s) should also address other aspects (eg societal political environmental economic
and regulatory) necessary to evaluate the practical implementation of AP technologies
NB For convenience the timeline of these actions is presented in 3 distinct phases Some AP technologies are however
more advanced than others and could already be at or close to readiness for pilot projects Conversely certain fundamental
knowledge and technology issues cannot expect to be resolved in the short term Accordingly the different phases as
proposed within the roadmap should not be considered to define a strictly chronological sequencetiming of actions
12
Visualisation of the AP technology development roadmap with illustrative project examples
Source Ecorys
Phase 1 Phase 3Phase 2
TRL 9 Industrial Implementation
TRL 6-8 Demonstrator
TRL 3-6 Pilot Projects
TRL 1-3 Fundamental
2017 2025 2035
Example projects- Research on metabolic and genetic engineering of strains for photosynthetic microbial cell factories
- Research on strains for the production of a variety of chemicals polymers and fuels
- Research on the understanding of surface chemistry at electrolyte-absorber interface in PEC
- Development of novel water-oxidation catalysts for direct water splitting
- Research on improvements of light absorption and carrier separation efficiency in PEC devices
- Research on new materials for electrodes and electrolytes in electrolysis cells
-Research to improve the basic understanding of reaction mechanisms in co-electrolysis (dynamics of adsorptiondesorption of gases gas transfer degradation mechanisms etc)
Example of projects - Improvements of operating stability of microbial cell factories
- Improvements of bionic leaf device design
- Study on long-term durability of molecular components used in DS-PEC devices development of active photosensitizer and catalyst
- Improvement of device stability and STH production efficiencies for direct water-splitting devices at pilot plant scale
- Support the development of lab-scale modules and demonstration facilities of electrolysis cells for CO2 valorisation
- Support the upscaling of cells for efficient co-electrolysis of H2O (steam) and CO2 in Solid Oxide Electrolysis Cells (SOEC)
- Development at a near-commercial scale of demonstrator plant(s) for co-electrolysis
Example of projects- Pilot plant scale of photobioreactors for photosynthetic microbial cell factories
- Pilot plant scale of ldquobionic leafrdquo devices
- Development at a near-commercial scale of demonstrator plant(s) for direct water-splitting devices based on several absorber materials (eg dye-sensitised photo-electrochemical cell (DS-PEC) device silicon-based tandem absorber structures)
13
Supporting activities
Looking beyond the technological and operational aspects of the roadmap the study finds several areas
where actions may be taken to provide a better understanding of the AP field and to accelerate development
and industrial implementation namely
Networking and coordination of research With the exception of the few pan-European initiatives (eg AMPEA
and FP7 projects) the degree of collaboration among research groups is low Networking and coordination
activities (for example through Horizon 2020 Coordination amp Support Action - CSA) would contribute to reduce
duplication of efforts and facilitate exchange among researchers
Industry engagement and technology transfer Engagement of industry in development activities which has so
far been relatively limited will become increasingly important as AP technologies move to higher levels of
readiness for commercial implementation Encouraging active involvement of industrial players in research
projects could ease the transfer of technology from the research community to industry (or vice versa) thereby
helping expedite the evolution from prototypes and pilots to marketable products
Public policy and regulatory conditions To encourage industrial implementation and market penetration AP
technologies and products should face a legal and regulatory environment that offers a ldquolevel playing fieldrdquo
compared to other energyfuel types Beyond this reflecting the sustainability and environmental
characteristics of AP there may be a public policy justification for creating a regulatory and legal framework
and possibly other measures to specifically encourage the adoption and diffusion of AP technologies and
products
Safety concerns and societal acceptance AP technologies could potentially raise a number of public
concerns for example the safety aspects of the production storage distribution and consumption of AP-
based products the use of GMOs in synthetichybrid AP processes the use of rare expensive andor toxic
materials extensive land use requirements etc Such legitimate public concerns need to be identified
understood and properly addressed if AP is to overcome barriers to widespread societal acceptance These
aspects should be an integral part of an overall AP research agenda that provides for open dialogue even
from very early stages of technological development and identifies potential solutions and mitigating
measures
Protection of Intellectual Property To become a successful leading player in the development and industrial
application of AP technologies researchers and industry must be able to adequately protect their intellectual
(industrial) property rights (eg patent protection) without this becoming a barrier to overall technology
development and implementation It will be important to both protect European intellectual property rights
while also follow global developments in AP-related patent-protected technologies thereby ensuring that
Europe has a secure strategic position in the AP field and avoiding potentially damaging dependencies on
non-European technologies
15
Table of contents
Abstract 5
Executive Summary 7
Table of contents 15
1 Introduction 21
2 Scope of the study 23
21 Overview of natural photosynthesis 23
22 Current energy usage and definition of artificial photosynthesis 25
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the study29
231 Synthetic biology amp hybrid systems 31
232 Photoelectrocatalysis of water (water splitting) 31
233 Co-electrolysis 31
3 Assessment of the technological development current status and future perspective 33
31 Synthetic biology amp hybrid systems 34
311 Description of the process 34
312 Current status review of the state of the art 35
313 Future development main challenges 38
32 Photoelectrocatalysis of water (water splitting) 39
321 Description of the process 39
322 Current status review of the state of the art 41
323 Patents 44
324 Future development main challenges 45
33 Co-electrolysis 47
331 Description of the process 47
332 Current status review of the state of the art 52
333 Patents 53
334 Future development main challenges 54
34 Summary 54
4 Mapping research actors 57
41 Main academic actors in Europe 57
411 Main research networkscommunities 57
412 Main research groups (with link to network if any) 59
42 Main academic actors outside Europe 62
421 Main research networkscommunities 62
422 Main research groups (with link to network if any) 64
43 Level of investment 66
431 Research investments in Europe 67
432 Research investments outside Europe 71
44 Strengths and weaknesses 73
441 Strengths and weaknesses of AP research in general 73
442 Strengths and weaknesses of AP research in Europe 74
16
45 Main industrial actors active in AP field 76
451 Industrial context 76
452 Main industrial companies involved in AP 76
453 Companies active in synthetic biology amp hybrid systems 77
454 Companies active in photoelectrocatalysis 79
455 Companies active in co-electrolysis 82
456 Companies active in carbon capture and utilisation 83
457 Assessment of the capabilities of the industry to develop AP technologies 85
46 Summary of results and main observations 86
5 Factors limiting the development of AP technology 91
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges 91
52 Current TRL and future prospects of investigated AP RTD initiatives 95
53 Knowledge and technology gaps of investigated AP RTD initiatives 95
54 Coordination of European research 100
55 Industry involvement and industry gaps 101
56 Technology transfer opportunities 104
57 Regulatory conditions and societal acceptance 107
6 Development roadmap 109
61 Context 109
611 General situation and conditions for the development of AP 109
612 Situation of the European AP research and technology base 110
62 Roadmap overview 111
621 Knowledge and technology development 111
622 Supporting and accompanying activities 117
7 References 121
17
List of figures
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton
gradient NADPH and ATP 24
Figure 22 Worldwide consumption of fuel types by percentage 27
Figure 31 General development and supply chain 33 Figure 32 Diagrammatic representation of a PSI-platinum hybrid system 34
Figure 34 Photoelectrochemical cell capable of water oxidation using solar energy 40
Figure 35 PEC reactor types 42
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting
photoelectrochemical cells 47 Figure 37 Schematic diagram of water electrolysis being conducted in an alkaline electrolyser 48
Figure 38 Schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell 49
Figure 41 Research groups in Artificial Photosynthesis in Europe 62
Figure 42 Research groups active in the field of AP globally 66
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020 69
Figure 44 Hondarsquos sunlight-to-hydrogen station 80
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels 85
Figure 61 General development roadmap visualisation 112
19
List of tables
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
36
Table 01 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the
performance data for each device This table was originally constructed by Ursua et al 201211
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis
cell electrolysers This table was originally constructed by Carmo et al 20138 53
Table 41 Number of research groups and research institutions in European countries 59
Table 42 Number of research groups per research area (technology pathway) 60
Table 43 Number of research groups and research institutions in non-European countries 64
Table 44 Number of research groups per research area (technology pathway) 65
Table 45 Investments in the field of artificial photosynthesis 66
Table 46 EU FP6 and FP7 projects on artificial photosynthesis 68
Table 47 Total EU budget on artificial photosynthesis per technology pathway 68
Table 48 Summary of strengths and weaknesses of research globally 73
Table 49 Summary of strengths and weaknesses of research in Europe 75
Table 410 Overview of the size of the industrial community number of companies per pathway 77
Table 411 Organisations in synthetic biology amp hybrid systems 78
Table 412 Organisations in the field of photoelectrocatalysis 79
Table 413 Companies in co-electrolysis 82
Table 414 Organisations active in carbon capture and utilisation 83
Table 415 Summary of findings size of research community 87
Table 416 Summary of findings size of industrial community 89
21
1 Introduction
To establish a world-class technology and innovation sector that is fit to cope with the challenges up to 2020
and beyond the European Commission initiated an update of its EU energy research and innovation (RampI)
policy leading to the publication of the Communication ldquoTowards an Integrated Strategic Energy Technology
(SET) Plan Accelerating the European Energy System Transformation (C (2015) 6317 final) in September
2015 Under the heading ldquoKeeping Technology Actions Openrdquo the SET Plan Integrated Roadmap states that
ldquothe emergence of new technologies required for the overall transition of the energy sector towards
decarbonisation requires breakthroughs which have to be based on fundamental and generic knowledge at
the international state of artrdquo Artificial Photosynthesis counts among the most promising new technologies and
is often considered as a potential ldquogame changerrdquo technology in the fields of energy conversion and energy
production
The study ldquoAssessment of artificial photosynthesisrdquo has been implemented in the first semester of 2016
against this background the study aims to support future policy developments in the area in particular in the
design of public interventions allowing to fully benefit from the potential offered by the technologies The study
has three specific objectives The first objective is to provide a detailed review of the state of the art of artificial
photosynthesis technologies as well as an inventory of research players from the public and private sector
The second objective is to analyse the factors and parameters influencing the future development of these
technologies The third objective is to provide recommendations for public support measures aimed at
maximising this potential
The structure of the report is as follows Section 2 describes the scope of the study with a review of the
different types of Artificial Photosynthesis Section 3 provides an assessment of the technological
development based on a review of the literature Section 4 maps the main academic and industrial actors
Section 5 analyses the factors limiting the development of Artificial Photosynthesis technologies and a
development roadmap is presented in the Section 6
23
2 Scope of the study
21 Overview of natural photosynthesis
Photosynthetic and heterotrophic organisms exist together in a steady state in the biosphere Photosynthetic
organisms capture solar energy in the form of photons this captured energy is used to produce chemical
energy that the organism uses to form adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide
phosphate (NADPH) ATP and NADPH are then used to generate organic compounds such as carbohydrates
from water and carbon dioxide12
Photosynthesis can be broken down into two processes light-dependant
reactions and carbon-assimilation reactions where the latter are driven by the products of the light reactions
In the light reactions electrons are obtained from water molecules that have been oxidised in a process often
referred to as ldquowater splittingrdquo to form electrons (e-) hydrogen ions (H
+) and molecular oxygen (O2) The
electrons are driven through a series of membrane-bound carrier proteins including cytochromes iron-sulphur
proteins and quinones to produce a proton gradient which is used to generate ATP and NADPH this is
summarised in Figure 21 The carbon-assimilation reactions use NADPH ATP electrons and H+ to reduce
carbon dioxide in a series of enzymatic reactions to generate an array of compounds21213
The light-dependent and carbon assimilation reactions of photosynthesis take place in the chloroplasts of
eukaryotic cells Chloroplasts are intracellular organelles with a non-uniform shape similar to that of
mitochondria They both have inner and outer membranes that enclose an inner compartment which is
permeable to small molecules and ions respectively The thylakoid membrane contains the photosynthetic
pigments and enzyme complexes that carry out the light reactions and ATP synthesis and are on the inside of
the inner membrane Chlorophylls are present in the thylakoid membrane and are responsible for absorbing
solar energy in plants An array of chlorophylls is called a photosystem Chlorophylls are green pigments
consisting of long phytol chains with a polycyclic planar structure similar to the protoporphyr in haemoglobin
at the top of the molecule However instead of a Fe2+
at the centre there is a Mg2+
coordinated by four
nitrogen atoms The phytol chain is esterified to a carboxyl group in ring IV The groups on the edge of the ring
(=CH2 and -CH3) can be exchanged for other groups depending on the organism the chlorophyll is present in
The heterocyclic five-ring system that surrounds Mg2+
has an extended polyene structure with alternating
single and double bonds These compounds strongly absorb in the visible region and have high extinction
coefficients Plants always contain chlorophyll α and chlorophyll β which both absorb green light at slightly
different wavelengths this maximises the amount of light the organism can utilise Chlorophylls bind with
specific proteins and membranes to form light-harvesting complexes (LHCs) In addition to chlorophylls which
are the main pigments in plants there are accessory pigments called carotenoids that absorb photons that
have different wavelengths so more of the spectrum can be utilised When a photon is absorbed by a
chlorophyll an electron in the chromophore portion is raised to a higher energy state called the excited state
When the electron moves back down to its ground state it can release the energy as light or heat In
photosynthesis instead of the energy being released as light or heat it is transferred from the excited
chromophore to a neighbouring chromophore in a process called ldquoexcitation transferrdquo1213
All of the pigment molecules in a photosystem can absorb photons and transfer the energy to other pigments
but only a number of pigments are associated with the photochemical reaction centre (PRC) The excitation
energy can be passed through multiple pigment molecules until it reaches a pigment associated with the PRC
The PRC transduces the excitation energy into chemical energy by passing the excitation energy to a nearby
molecule acting as an electron acceptor This leaves the chlorophyll with a positive charge which is
neutralised by another electron donor the electron acceptor becomes negatively charged In this way
excitation caused by photon absorption causes electric charge separation and starts the oxidation-reduction
chain Light-driven electron transfer in chloroplasts during photosynthesis is carried out by a number of multi-
enzyme complexes in the thylakoid membrane1213
24
Photosynthetic bacteria usually have one or two reaction centres Purple bacteria pass electrons through a
pheophytin which is a chlorophyll without the Mg2+
at the centre of the ring to a quinone Green sulphur
bacteria pass electrons through a quinone to an iron-sulphur centre The photosynthetic machinery in purple
bacteria is made up of 3 basic units a single reaction centre (P870) a cytochrome bc1 electron-transfer
complex (similar to complex III found in mitochondria) and an APT synthase Absorption of a photon drives
electrons through pheophytin and a quinone to the cytochrome bc1 complex following which electrons pass
through this complex to the cytochrome bc1 complex and back to the reaction centre This movement of
electrons generates the energy needed by the cytochrome bc1 complex to pump protons across the
membrane and create the gradient that generates ATP1213
The photosynthetic apparatus of cyanobacteria and plants is more complex than that found in a one-system
bacterium due to them containing two photosystems in the thylakoid membrane Photosystem II acts like the
single photosystem found in purple bacteria It should be noted that the water-splitting reaction occurs at
PSII14
When the reaction centre of photosystem II (P680) is excited electrons are driven through the
cytochrome b6f complex which pumps hydrogen ions across the thylakoid membrane to generate a proton
gradient PSI aids in the reduction of NADP+ to NADPH by absorbing a photon at 700 nm to excite an
electron which is passed through a number of carrier molecules to plastoquinone and then to ferredoxin-
NAPD+ reductase which generates NADPH As previously discussed the proton gradient that has been
generated from transferring the electrons that were excited by the photons is used by ATP synthase to
generate ATP To summarise the light-dependent reactions cause water to split into oxygen electrons and
protons which are used to generate a proton gradient form NAPDH from NAPD+ and generate ATP The
main differences between the two photosystems are the wavelengths of light they absorb and that PSII
conducts water oxidation (while PSI does not) Both absorb photons and both are capable of generating
ATP12-16
In the carbon-assimilation reactions ATP and NADPH are used to reduce (gain electrons) carbon
dioxide to form phosphates starch and sugars as part of the Calvin cycle which takes place in the stroma
this process is also known as carbon fixation1213
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton gradient NADPH and ATP
Theoretically the efficiency of natural photosynthetic systems should be around 26 This is calculated by
knowing the energy content of a glucose molecule is 672 kcal mol-1
To generate a glucose molecule 48
photons with a wavelength of 680 nm are needed which together have an energy of 42 kcal per quantum
mole which is equal to 172 kcal mol-1
672 kcal mol-1
divided by 172 kcal mol-1
makes for 26 efficiency
However in reality an efficiency of less than 2 is usually achieved in optimal conditions17
The efficiency of
natural photosynthetic systems is limited by electron-hole recombination which is when the charge separation
25
process is not successful Even when this process is successful up to half of the energy from the excited state
of the chlorophyll is used2 Energy is also used by the organism to ensure other processes within the cell are
functioning The inefficiencies of natural photosynthesis highlight major areas where researchers are looking
to improve in artificial photosynthetic systems and are discussed over the next sections
Photodamage occurs in photosynthetic systems when solar energy cannot be effectively dissipated as heat or
be used to form photosynthetic products fast enough Upon photon absorption chlorophylls are excited to a
singlet state whereby under normal conditions the chlorophyll molecule will either pass the energy to another
chlorophyll molecule by FRET emit a photon or dissipate the energy as heat High levels of light increase the
amount of photosynthesis occurring as well as the amount of time chlorophylls spend in their singlet state
which increases the risk of chlorophylls forming longer-lived triplet states if the energy is not passed on or
dissipated fast enough Chlorophylls in their triplet state can photosensitise toxic chemicals such as singlet
oxygen which causes photodamage18
Natural photosynthetic systems limit photodamage with a process
called non-photochemical quenching using molecules called carotenoids that quench chlorophyll triplet states
by triplet-triplet energy transfer Carotenoids in their triplet state are low energy and quickly release their
energy through heat production and do not facilitate the production of singlet oxygen1213
This method of
photoprotection has been mimicked in artificial photosynthetic systems to extend their lifetimes and enable
them to work under intense light conditions
22 Current energy usage and definition of artificial photosynthesis
The current demand for energy is primarily met by the combustion of fossil fuel resources in the form of coal
crude oil and natural gas
26
Figure 22 shows that the energy demand has doubled over the last 40 years and it should be noted that this
demand is expected to double again by 205031719
The increased energy demand could be met by increasing
fossil fuel combustion However fossil fuel combustion is not a clean process and releases large amounts of
greenhouse gases such as carbon dioxide carbon monoxide and nitrogen oxides The accumulation of these
greenhouse gases in the atmosphere is increasing the average global temperature damaging the ozone layer
and causing more extreme weather2021
From these studies it is clear that using fossil fuels to meet the future
energy demand could cause irreversible damage to the environment and the human population2223
Due to
this much time money and resources are being dedicated to find clean stable and renewable energy
alternatives to fossil fuels2425
Current candidates include wind power tidal power geothermal power and
solar energy while the viability of nuclear power is currently under discussion due to the radioactive wastes
and potential emergency risks The majority of these technologies are currently expensive to operate
manufacture and maintain and produce rather small amounts of energy due to their low efficiencies This
report will focus on how solar energy is being utilised as a renewable energy source The sun provides
100x1015
watts of solar energy annually across the surface of the earth If this solar energy could be
harnessed with 100 efficiency the current energy demand for one year could be met within an hour In total
only 002 of the total solar energy received by earth over a year would be required161726
27
Figure 22 Worldwide consumption of fuel types by percentage Total fuel consumption was equal to 4667 Mtoe in 1973 and 9301
Mtoe in 2013 and is represented by the size difference of the two charts below The figure was adapted from The 2015 Key
World Energy Statistics report3 Mtoe = million tonnes oil equivalent This figure does not state whether the energy came
from a renewable source
Currently one of the best and most developed methods of utilising solar energy (photons) is by using
photovoltaic cells that absorb photons and generate an electrical current This electrical current can be
instantly used as a source of energy or it can be stored in a wide variety of batteries for later use There are a
number of disadvantages to solely relying on photovoltaics to provide us with all of our energy requirements
which are listed below
Photovoltaics can only be used in areas that have high year-round levels of sunlight
The electrical energy has to be used immediately (unless it is stored)
Batteries used to store electrical energy are currently unable to store large amounts of energy have short
lifetimes and their production generates large amounts of toxic waste materials
To address these disadvantages researchers are looking into ways that solar energy can be stored as
chemical energy instead of inside batteries as electricity This is the point where the research being conducted
begins to draw inspiration from photosynthetic organisms14
Photosynthetic organisms have been capable of
utilising solar energy to generate a multitude of complex molecules for billions of years27
Natural
photosynthetic systems are capable of producing two main fuel types hydrogen and carbon-based fuels
Hydrogen is generated from photon-driven in PSII and carbon-based fuels such as carbohydrates and lipids
are generated from the reduction of carbon dioxide with hydrogen (Calvin cycledark reactions)1628
Hydrogen
and carbon-based fuels are the main fuel types researchers aim to produce using artificial photosynthetic
systems29
Hydrogen is produced by splitting (oxidising) water with solar energy catalysts and water oxygen
is a by-product of water oxidation Hydrogen is the simplest fuel to produce and the majority of the
technologies discussed in this report have already had success producing it It is desirable however for
researchers to generate more complex carbon-based fuels such as carbon monoxide methane methanol and
higher order carbon-based compounds using solar energy carbon dioxide and water because carbon-based
fuels have a higher energy density than hydrogen and are used as our primary energy source It should be
noted that hydrogen does not exist in its molecular form in nature which means that it must be produced by
an energy input Hydrogen is most commonly produced by steam reforming natural gas or fossil fuels such as
propane diesel methanol or ethanol8 These methods produce low purity hydrogen and consume fossil fuels
so they do not relieve any fossil fuel dependencies and they further contribute to environmental concerns
In later sections of this literature review some of the main technologies that utilise artificial photosynthesis to
generate fuel molecules are discussed These technologies offer a potential method by which high purity
hydrogen can be produced by the water-splitting reaction using energy obtained from renewable sources
Hydrogen carbon monoxide and carbon dioxide are important feedstocks for making industrial products such
as fertilisers pharmaceuticals plastics and synthetic liquid fuels With more research it is hoped that it will
soon be possible to produce complex molecules from chemical feedstocks that have been produced using
28
renewable energy Technologies that directly convert solar energy to electrical energy (photovoltaics) have
been commercialised for a number of years and can generate electricity on a megawatt scale at large
facilities Success has also been gained with generating hydrogen with a number of technologies such as
biological hybrid systems photoelectrocatalysis and electrolysers (some sub-technologies in this pathway
have been commercialised and can produce power on a megawatt scale) which will also be discussed in this
literature review Some success has been had with generating these more complicated molecules by artificial
photosynthesis from chemical feedstocks but it should be noted that these technologies are still at an early
research and development stage Using recent literature a definition for artificial photosynthesis was
developed for this study and is provided below
Artificial photosynthesis is a process that aims to mimic the physical chemistry of natural
photosynthesis by absorbing solar energy in the form of photons and using the energy to
generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
This is a broad definition of artificial photosynthesis where the term physical chemistry includes any reaction
or process that takes place during natural photosynthesis The term fuel molecules encompasses the term
solar fuel and can include any molecule that the system has been designed to produce such as molecular
hydrogen hydrocarbons alcohols and carbohydrates Biomimetics refers to a system that aims to mimic a
biological system by including some aspects of a biological system such as photosystems I and II chlorophyll
molecules or the electron transport proteinsmolecules Nanotechnology can refer to systems that use organic
chemistry inorganic chemistry or surfaceinterface chemistry to generate artificial photosynthetic systems
Synthetic biology refers to biological systems that have been genetically engineered to either allow or prevent
a biological process to occur
To date much progress has been made in the development of artificial photosynthetic systems since the
conception of the term22628-35
The most common problems associated with artificial photosynthetic systems
arise from
Low efficiency
Inability to utilise the entire spectrum of photon wavelengths
Inability to efficiently separate the charged species
Most systems use expensive noble metals to conduct the chemistry36
Short device lifetimes
Should these synthetic fuels be produced at a large enough scale for commercial use a new set of problems
would appear associated with how the fuels should be stored and distributed Using artificial photosynthesis to
generate hydrocarbons that are already used as an energy source would require fewer infrastructural changes
than switching to a hydrogen economy Furthermore the production process needs to be easily scalable so
that fuels can be produced in a cost-effective way on a terawatt scale in a manner that can keep up with the
ever-increasing energy demand In the next section several different types of artificial photosynthesis
technologies are introduced that aim to effectively utilise solar energy
29
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the
study
Research and development related to the area of artificial photosynthesis encompass several technological
areas The different pathways for artificial photosynthesis are illustrated in
30
Figure 22 along with some of the compounds that can be generated from these technologies on their own or
by combining them It should be noted that while Figure 23 presents a broad selection of potential compounds
that can be produced the actual number of compounds that could potentially be generated by artificial
photosynthetic systems is limitless
Figure 23 Different routes by which artificial photosynthesis can take place and the products that can be generated by utilising the
different technologies This image was generated by The University of Sheffield PV = Photovoltaics
The efficiency and usefulness of artificial photosynthetic technologies are dependent on how well they can
perform three distinctive steps that are found in natural photosynthetic organisms namely
How efficiently they are able to capture incoming photons (percentage of the spectrum that can be
utilised)
How efficiently the system can transfer the energy to a reaction centre (minimising energy loss during the
transfer)
How well the system can generate and separate charges to allow the desired chemical reaction to take
place (preventing charge recombination)
The complexity of artificial photosynthetic systems occurs when multiple charges have to be separated for a
chemical reaction to occur The production of hydrogen and oxygen from the water-splitting reaction which is
probably the simplest reaction these systems must be capable of still involves the transfer of four electrons
and the generation of more complicated compounds will require even more charge-separation events to occur
The following sections discuss the artificial photosynthetic technologies as depicted in
31
Figure 22 which are synthetic biologyhybrid systems photoelectrochemical catalysis and co-electrolysis
231 Synthetic biology amp hybrid systems
This pathway aims to take existing biological systems that perform different stages of photosynthesis such as
the light-harvesting charge separation or molecule synthesis steps and combine them so they are able to
produce specific fuel molecules These biological molecules can be modified or combined with other biological
molecules or synthetic organicinorganic compounds so that they are able to produce specific fuel molecules
more efficiently It is known that natural photosynthetic systems contain a number of crucial components that
need to be included in synthetic biology and hybrid artificial photosynthetic systems For example they should
contain a light harvester (semiconductor or molecular dye) a reduction co-catalyst (hydrogenase mimic or
noble metal) and an oxidation co-catalyst (photosystem II mimic that is capable of producing molecular oxygen
and hydrogen) It should be noted that these technologies are at a very early stage of development
(laboratory level technology readiness level (TRL 1-4)) and are many years away from being commercialised
Briefly researchers are capable of producing small quantities of hydrogen through the water-splitting reaction
and have demonstrated the reduction of carbon dioxide to methane and acetate Researchers are also
investigating the possibility of using basic cells (biological) to host biological machinery that is capable of
generating more complex fuel molecules The long-term goal of these technologies will be to reliably generate
large quantities of specific fuel molecules from simple starting compounds such as hydrogen and carbon
dioxide which are combined and converted into a series of different compounds using a series of enzymes
and synthetic organic and inorganic catalysts
232 Photoelectrocatalysis of water (water splitting)
This pathway aims to develop efficient photovoltaics and photoelectrochemical catalysts that utilise earth-
abundant metals capable of generating oxygen and hydrogen through the water-splitting reaction38
Photovoltaics can be used to generate electrical energy directly from sunlight Photovoltaicssemiconductors
can be used in photoelectrochemical cells to produce hydrogen from the water-splitting reaction PVs and
PECs are among the most advanced areas of artificial photosynthesis Photovoltaics utilise semiconductor
materials that are capable of directly generating electrical currents (electrical energy) when exposed to certain
wavelengths of light These semiconductors have to be capable of utilising a range of photon wavelengths
efficiently and must have long lifetimes Photovoltaics have been commercialised and are producing power on
a megawatt scale Future developments in this field aim to increase device efficiency and lower the costs
associated with them (TRL 7-8) Photoelectrochemical cells are capable of producing electricity and fuel
molecules when exposed to certain wavelengths of light Fuel molecules such as hydrogen are produced by
electrolysing water (splitting water) which could provide an unlimited source of hydrogen that could be used to
generate power or reduce carbon dioxide Water-splitting cells require semiconductors that are able to support
rapid charge transfer at the semiconductoraqueous interface have long-term stability in aqueous
environments and are capable of utilising a range of photon wavelengths30
233 Co-electrolysis
This pathway provides an alternative method by which water oxidation can be performed Alkaline
electrolysers and polymer electrolyte membrane electrolysers have been mature technologies now for a
number of years and are capable of converting water and electricity to hydrogen and oxygen The co-
electrolysis pathway aims to use carbon dioxide-water co-electrolysis to generate syngas (COH2) which is
produced by simultaneously reducing carbon dioxide and water using high temperature solid oxide cell
electrolysers (SOECs)39
Syngas can be used to generate simple intermediate compounds that can be used
as feedstock for more complicated chemicals used in fertilisers pharmaceuticals plastics and synthetic liquid
fuels Methanol is an example of a simple molecule that can be made from syngas The dehydration of
methanol can be used to generate the cleaner fuel dimethyl ether which is being considered as a future
energy source40
As a technique to produce power co-electrolysis offers a number of advantages over other
techniques such as photovoltaics and wind power in that it is not site-specific and can continuously generate
32
power However these devices require large amounts of electricity to function which affects their operating
costs It is likely that these systems will have their electricity supplied to them by solar or wind power farms in
the near future
33
3 Assessment of the technological development current status and future perspective
This literature review will focus on three technologies (synthetic biologybiological hybrid systems
photovoltaicsphotoelectrochemical cells and co-electrolysis) that are currently using artificial photosynthesis
to generate energy in the form of electricity and fuels The majority of research into these technologies has
focused on improving device efficiencies lifetimes and producing hydrogen The review will conclude with
discussions about the fuels researchers are currently producing potential large-scale facilities to produce the
fuels and finally the potential directions research into artificial photosynthesis could pursue Figure 3 shows a
general development and supply chain for technologies that aim to use artificial photosynthesis to convert
solar energy into power and fuels It should be noted that each technology will have its own set of specific
challenges which will be discussed at the end of each respective section This literature review was
constructed using material from a number of sources such as peer-reviewed journals official reports and
patents that have been filed
Figure 31 General development and supply chain for technologies that aim to use a combination of photovoltaics and
photoelectrochemical cell artificial photosynthetic technologies to convert solar energy into power and fuels
34
31 Synthetic biology amp hybrid systems
311 Description of the process
Artificial photosynthetic systems that utilise synthetic biology aim to modify existing natural photosynthetic
systems at the genetic level or combine them with other biological systems and synthetic compounds to
produce a specific fuel or improve efficiency It should be noted that technologies based on using synthetic
biology and hybrid systems to produce solar fuels are still at the research and development stage (TRL 1-4)
however the use of these systems to produce a limited number of fine chemicals is more advanced with a TRL
3-7 The majority of technologies developed in this pathway have focused on producing hydrogen and only a
limited number of technologies are capable of producing more complex fuel molecules It should also be noted
that most of these systems are only capable of producing small amounts of fuel molecules for a short period of
time Natural photosynthetic systems can be broken down into three distinct processes that these systems
have to mimic light-harvesting energy transfer and charge generationseparation (catalytic reactions)1437
For
these technologies to be successful the systems have to be designed so that they consist of electron donors
and acceptors and attempt to mimic light-driven charge separation2 Generally these technologies aim to
combine biological molecules that have catalytic activity (enzymes such as PSI [NiFe]-hydrogenase and
[FeFe]-hydrogenase) or combine the enzymes with synthetic inorganic and organic compounds9 Examples of
when these systems have been successfully created are discussed below with figures and the TRLs of the
technologies are given after each technology has been discussed
Illustrations
Figure 32 A simplified diagrammatic representation of a PSI-platinum hybrid system that is used to generate H2 can be found below
showing PSI P700 chlorophyll a apoprotein A1 (red) and PSI P700 chlorophyll a apoprotein A2 (blue) The electron provided
by ascorbate is transferred to a cytochrome c6 where a photon excites the electron which is then passed through PSI where
it is transferred to the platinum (Pt) catalyst to generate molecular hydrogen This figure drew inspiration from Fukuzumi
2015 and Gorka et al 20149
35
Figure 33 A diagrammatic representation of a FeFe-hydrogenase I ndash cadmium sulphur (CdS) hybrid system that is used to generate
H2 The faded red structure represents the surface topography of FeFe-hydrogenase I the blue arrows represent the
movement of the electrons through the Fe-S clusters where hydrogen ions are converted to H2 and the yellow structures
represent the CaI capped CdS nanorods The figure was constructed using inspiration from Wilker et al 2014 using the
PBD file 3C8Y and edited using PyMol software12
312 Current status review of the state of the art
The first example of researchers successfully producing light-driven hydrogen from an artificial complex
composed of biological molecules and platinum was achieved by combining the PSI subunit PsaE from
Thermosynechococcus elongtus with an oxygen tolerant [NiFe]-hydrogenase from Ralstonia eutropha H16 to
form a PSI-hydrogenase complex This complex in presence of ascorbate (electron donor) was capable of
light-driven hydrogen production at a rate of 058 microM (mg chlorophyll)-1
h-1
41-43
(TRL 3)
Hydrogenases are enzymes that catalyse the reversible oxidation of molecular hydrogen while platinum is
also capable of reversibly photocatalytically oxidising hydrogen44
Researchers recently showed that when a
platinum nanocluster was attached to a PSI molecule the complex was able to produce hydrogen at a rate of
673 microM (mg chlorophyll)-1
h-1
- the general structure of this complex is highlighted in Figure 323
Systems
based on these original concepts have been optimised to achieve higher hydrogen production efficiencies of
up to 244 microM (mg chlorophyll)-1
h-1
It should also be noted that the electron donor (ascorbate) had to be
present in excess in both cases2345
It should also be noted that these hydrogen production rates are
comparable to those of natural photosynthetic systems which occur at a rate of ca 300 microM (mg chlorophyll)-1
h-1
46
(TRL 3-4)
Researchers recently proposed a model by which hydrogen can be generated using CaI capped CdS
nanorods The authors reported that light is absorbed by the CdS nanorods to excite two electrons which are
then transferred into the CaI cap where the two electrons are used to reduce two protons (H+) and generate
hydrogen (electrons are replaced in CdS by ascorbate) In a recent publication the authors showed that it is
possible to combine the CdSCaI nanorods with [FeFe]-hydrogenase in place of PSI (ascorbate is used as an
electron donor) In this biomimetic system the electrons are transferred to [FeFe]-hydrogenase where they
reduce H+ to hydrogen This system was shown to have a quantum efficiency of 20 be active for up to 4
hours and had a total turnover of 106 hydrogen before activity was lost The loss in activity was found to be
due to the inactivation of the CaI cap at the end of the CdS rod147
36
Figure 3 represents the system and process described above where the blue arrows represent the movement
of electrons from the CdSCaI nanorods to the iron-sulphur clusters in [FeFe]-hydrogenase (TRL 3-4)
Researchers were recently able to produce hydrogen using a PSI-cobaloxime complex when it was
illuminated with natural light Cobaloximes are vitamin B12 mimics capable of catalysing H+ reduction
Cobaloximes offer a number of advantages over hydrogenases in that they are not sensitive to oxygen their
synthesis is relatively simple and they are constructed from relatively cheap materials In this system sodium
ascorbate used a sacrificial electron donor and cytochrome c6 transported the electrons to the PSI-cobaloxime
complex Upon light absorption the electrons were excited and transported through PSI to the bound
molecular catalyst cobaloxime where hydrogen production occurs27
The maximum rate for the photoreduction
of water by this hybrid system was measured to be 170 mol hydrogen (mol PSI)-1
min-1
as was reached within
10 minutes of illumination It should be noted that after 90 minutes hydrogen production levelled off giving a
total turnover of 5200 mol hydrogen mol PSI-1
27
It is thought that the activity of the hybrid decreased due to
the dissociation of cobaloxime from PSI research efforts are currently underway to stabilise the hybrid
system27
This system is of particular merit because the PSI-cobaloxime hybrid is composed of earth-
abundant materials unlike the hybrid systems containing precious metals It should also be noted that there
are multiple molecular catalysts for hydrogen production other than the cobaloximes that can offer improved
stability solubility in water and better activity and have been discussed in a recent review6 (TRL 3-4)
The production of hydrogen at a rate of 2200 plusmn 460 micromol mg Chl-1
h-1
(a faster rate than natural photosynthetic
systems) has recently been demonstrated This was accomplished by generating a hybrid system consisting
of a PSI complex tethered to a [FeFe]-hydrogenase using a 18-octanedithiol nanowire and also crosslinking
cytochrome c6 to the PSI complex This four component system was then placed in a sodium phosphate buffer
containing the electron donor sodium ascorbate at pH 65 and illuminating the sample with natural light48
The
authors also reported results for complexes consisting of different nanowire lengths (3-10 carbons) and a
chain length of 8 carbons was found to give the highest hydrogen production rates this is most likely due to
the chain being long enough to minimise steric hindrance between the two proteins The hybrid system
retained its activity for up to four hours and it should be noted that the decrease in activity was attributed to
depletion of the electron donor (full activity was regained upon replenishing the ascorbate) It should also be
noted that the hybrid system regained its full hydrogen-evolving activity after being stored in anoxic conditions
at room temperature for 100 days48
(TRL 3)
The technologies above are only a few examples of the methods researchers have used to generate hydrogen
from hybrid systems Table 31 below summarises hydrogen production rates by a number of different hybrid
systems that all incorporate PSI into their complex The information in Table 31 was originally summarised by
Utschig et al 20156 All of the technologies in this table have a TRL of 3-4
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
PSI-catalyst system Rate of H2 production
[mol H2 (mol PSI)-1 s
-1]
TON (time hours)
PSI-nanoclusters photoprecipitated long liveda 49
0002 ndc (2000)
PSI-[NiFe]-hydrogenase genetic fusion 41
001 ndc (3)
PSI-nanoclusters photoprecipitated short-liveda 49
013 ndc (2)
PSI-[FeFe]-hydrogenase-PetF in vitro complexb 50
031 ndc (05)
PSI-Ni diphosphinea 51
073 (3)
PSI-[FeFe]-hydrogenase-Fd protein complexb 50
107 ndc (1)
PSI-molecular wire-Pt nanoparticlea 52
11 (12)
PSI-NiApoFd protein deliverya 51
125 (4)
PSI-cobaloximea 27
283 (15)
PSI-Pt nanoparticlea 45
583 (4)
PSI-molecular wire-[FeFe]-hydrogenasea 48
524 ndc (3)
a Redox mediator Cyt c6
b Redox mediator PC
c nd not determined
37
Researchers have generated a hybrid photocatalyst system capable of splitting water to produce hydrogen
and oxygen and capable of reducing carbon dioxide by rational design The system uses a semiconductor as
the light harvester and a biomimetic complex mimicking photosystem I as a molecular catalyst37
This work
highlights that the understanding of artificial photosynthetic systems is increasing as rational design can now
be used to construct biomimetic artificial photosynthetic systems (TRL 2)
Unicellular organisms such as Chlamydomonas reinhardtii are a type of green algae that can produce
hydrogen light-dependently using the enzyme [FeFe]-hydrogenase However hydrogen production rates in
photoactive organisms are limited by a number of physiological constraints This is due to electrons
generated by PSI being used in a number of reactions other than hydrogen production5354
Most photoactive
organisms will contain a form of photosynthetic electron transport ferredoxin (PETF) protein which provides
photosynthetic electrons generated by PSI for a number of metabolic pathways All of these pathways
compete for electrons with [FeFe]-hydrogenase Researchers recently genetically modified the affinity PETF
has for PETF-dependent ferredoxin-NADP+-oxidoreductase (FNR) without comprising the affinity PETF has
for [FeFe]-hydrogenase In this modified system PETF is still able to supply [FeFe]-hydrogenase with
electrons that it used to produce hydrogen but is less able to supply electrons to FNR which means that fewer
carbon dioxide fixation reactions occur Hydrogen production rates increased by nearly 5x in wild type cells
that had modified PETF53
(TRL 3)
Microbial biocathodes consist of an electrode that has electrochemically active microorganisms immobilised
onto its surface which are capable of reducing protons to hydrogen These systems offer a number of
advantages in that the cathode can be constructed from cheap materials and the microorganisms can self-
regenerate55
The first microbial biocathode consisted of three phases (1) acetate and hydrogen are oxidised
at a bioanode that has been inoculated with a mixed culture of electrochemically active microorganisms to
release carbon dioxide (2) only hydrogen is fed into the bioanode (3) the polarity of the cells is reversed
(direction of electron flow) and hydrogen production begins at the cathode55
Initially after the polarity is
reversed methane was produced at the biocathode and not hydrogen (TRL 4)
Bio-catalysed electrolysis is a microbial fuel cell-based technology that is capable of generating hydrogen and
other reduced products from electron donors (acetatewastewater) however these systems require an
external power source56
In this system acetate is oxidised at the anode by microorganisms in the presence of
high concentrations of ammonium and the electrons are transferred to a platinum catalyst (cathode) where
they reduce protons to hydrogen56
(TRL 3)
A recent paper has reported the reduction of carbon dioxide to acetate and methane using a water-splitting
reaction to produce hydrogen and sodium bicarbonate as the carbon source using microbial electrosynthesis
(MES)57
This system used an assembly of graphite felt and a stainless steel cathode This paper is important
because it presents the use of electrode materials derived from earth-abundant elements showcasing them
as particularly suitable for industrial scale-out due to their low cost (TRL 3)
Researchers at the University of Oxford developed a biological tool called ldquoSimCellrdquo A SimCell is a simple
non-replicating cell that has no well-defined function until a plasmid containing DNA coding a specific
function is inserted into the cellrsquos genome The inserted DNA could potentially provide all of the genetic
information needed by the cell to produce the proteins and enzymes required to produce specific fuel
molecules The SimCell has been optimised to be simple so that most of the energy the cell is using will go
towards carrying out the function of the newly inserted gene instead of maintaining numerous intracellular
processes5859
The SimCell could allow researchers to insert genetic information that codes the production of
target fuels thereby greatly increasing the number of potential fuel targets and the efficiency with which they
can be produced It is possible that this technology could be patented once it reaches a higher level of
maturity and a working system is demonstrated (TRL 1)
38
313 Future development main challenges
Synthetic biology amp hybrid artificial photosynthetic systems primarily focus on producing hydrogen however
research focused on the production of hydrocarbons using technologies such as MES is gaining momentum
Although these technologies are currently at the laboratory research and development stage (TRL 1-4) they
are improving quickly At a very small laboratory scale the systems are becoming efficient enough to produce
hydrogen at a rate that is comparable to that which occurs in natural photosynthesis although some
researchers have reported even faster production rates
Synthetic biology amp hybrid systems need to address a number of specific challenges before they can be
considered as commercially viable options for producing solar fuels Below some preconditions and
challenges regarding certain such systems are described
Protein Hybrid Systems
For proteins to be active their primary amino acid sequence must fold and adopt the correctly folded
structure Misfolded proteins can exhibit severely diminished activities
Proteins (and enzymes) are inherently unstable and sensitive to the pH temperature pressure and buffer
components and will often degrade over time which limits their use
Most hydrogenases are sensitive to oxygen so they must be kept under anaerobic conditions
Biological molecules can be produced at a large scale as shown by the biopharmaceutical industry
However the amount of biological molecules needed to produce the amount of fuel required to support
mankind would be huge and has not been calculated
One of the strongest properties of enzymes is that they exhibit a high level of specificity they are able to
produce specific molecules of high purity
Enzymes can be redesigned to give them new or improved functions within different environments60
However modifying protein and enzyme function is not trivial it is often a time-consuming process that
requires thorough understanding of the system although predictive tools for protein engineering are
improving
Enzymes are often very large molecules in which only a small percentage of the amino acid residues are
actively involved in catalysis Researchers could reduce the complexity of biological systems drastically if
they focused on stripping the enzyme down so it contains only the residues and cofactors needed for
catalytic activity on a simplified base framework of amino acids
Microorganisms
In a recent paper researchers investigated how hydrogen production can be enhanced and suppressed in
vitro They state that the main limitations of hydrogen production in microorganisms are the systemrsquos
sensitivity to oxygen and the competition between hydrogenases and NADPH-dependent carbon dioxide
fixation If these issues can be solved the technologies would be closer to commercialisation50
It should be
noted that microorganisms are capable of producing a number of fine chemicals on a commercial scale (these
are often produced in smaller amounts)
Microorganisms are highly complex in that a multitude of chemical reactions must take place so that the
organism can continue to function at the most basic level These extra reactions are major drawbacks if
these organisms are to be used to produce fuel molecules as most of the absorbed energy cannot be
used to produce the fuel molecules
To overcome this problem various aspects of the organismsrsquo genetic information can be modified to
minimise energy loss through side reactions
SimCells are simplified cells in that number of chemical reactions needed to sustain the organism are
minimised this means that more energy can dedicated to fuel production However these technologies
are currently in early stages of research and development and are not close to being produced on an
industrial scale
39
It is likely that fuel-producing microorganisms will have to be capable of expelling the fuel molecules
otherwise the fuel-producing cells will have to be destroyed to obtain the molecules
A major advantage of bacterial systems is that their genetic information can be modified so that they
produce a number of different fuel molecules However this is not a trivial task and the microorganisms
may not be able to survive when large concentrations of the fuel molecules are present
Bacterial cells can survive in a number of harsh conditions and they do not have to be in an ultra-clean
environment
Synthetic biology and hybrid systems face a unique challenge in that these systems are made by or are
genetically modified organisms (GMOs) GMOs are often subject to negative media attention and are often
portrayed and viewed to be unsafe by the public which means that the public may not want their fuel coming
from this source Some of the concerns surrounding the use of GMOs are valid and need to be investigated
One of the main concerns about the use of GMOs pertains to whether the GMO could have a severe effect on
the environment if it managed to migrate into the wild However this issue could be addressed by only using
GMOs that are not able to replicate (ie they are obtained from a secured parent cell) However most of the
concerns the public may have regarding GMOs could be solved by educating about GMOs and providing a
large body of scientific evidence that supports their safety
It should be noted that the authors could find no relevant patents for artificial photosynthetic technologies that
utilise synthetic biology amp hybrid systems
In conclusion synthetic biology amp hybrid systems that produce solar fuels are currently in the laboratory
research and development stage and it is too early to determine whether they would be a commercially viable
option However current research is promising and shows that they could be a valuable part of generating
solar fuels due to their high level of specificity and ability to be reengineered to carry out new and specialised
chemistry
32 Photoelectrocatalysis of water (water splitting)
321 Description of the process
This pathway aims to develop efficient photovoltaics and photoelectrocatalysts that utilise earth-abundant
metals capable of generating oxygen and hydrogen by splitting water38
The water-splitting (water oxidation)
reaction is one of the most advanced areas of artificial photosynthesis These systems that directly produce
fuel molecules from sunlight are currently in the early researchproof-of-concept stage (TRL 2-4) This means
that they are a number of years away from being a commercially viable method to produce synthetic fuels31
Water oxidation involves the removal of 4e- and 4H
+ to generate molecular oxygen (O2) and molecular
hydrogen (H2) In nature water oxidation is carried out by photosystem II in natural photosynthetic systems
The water-splitting reaction has the potential to provide a clean sustainable and abundant source of
hydrogen that could be used as energy or to reduce carbon dioxide to higher order hydrocarbons which is
why a considerable amount of time and money has been spent trying to improve the process
Photovoltaic cells (PVs) also known as solar cells utilise semiconductor materials that are capable of directly
generating electrical currents when exposed to certain wavelengths of light Light absorption by the
semiconductor promotes an electron from the low energy valence band to the higher energy conduction band
This creates an electron-hole pair that can be transported through the electrical device to provide power
Research focusing on PVs has focused on improving their efficiencies Initially efficiencies lt1 were
obtainable but the most recent generation of PVs can achieve efficiencies gt45 Research has shown that
the efficiencies of PVs can be greatly improved by using multi-junction instead of single-junction devices60
Efficiencies of different PV models have increased over the last 40 years this plot is courtesy of the National
Renewable Energy Laboratory Golden CO The most recent PVs have long lifespans (gt20 years) low
40
pollution levels and low operating costs30
However PVs do have some drawbacks in that they are expensive
to manufacture can only be used during the day in areas that receive a lot of sunlight utilise a fraction of the
available spectrum and it is problematic to store the energy in batteries3360
Problems associated with long-
term storage of energy could be overcome by storing the energy in chemical bonds of molecules such as
hydrogen alcohols and hydrocarbons which is why the research in the following section is of importance It
should also be noted that PVs have a TRL of 9 as they have been successfully commercialised and can
provide power on a megawatt scale
Photoelectrochemical cells (PECs) are capable of producing fuel molecules when exposed to certain
wavelengths of light or paired with a semiconductor (PV) Hydrogen can be produced by the water-splitting
reaction Figure 3 shows a schematic diagram of a PEC which is capable of conducting water oxidation in
two separate chambers Currently there are two primary methods by which solar fuels can be generated from
the water-splitting reaction in PECs The first is by direct photoelectrocatalysis at the semiconductor-
electrolyte interface (occurring at a solid-liquid junction) and the second is by coupling the electrochemical
(PEC) reaction directly to a buried p-n junction PV230
Both of these approaches require the generation of a
photovoltage sufficient to split water (gt 123 V)30
Photoelectrodes in PECs must have high surface stability
good electronic properties and suitable light absorption characteristics Water-splitting cells require
semiconductors that are able to support rapid charge transfer at the semiconductoraqueous interface have
long-term stability in aqueous environments and are capable of utilising a range of photon wavelengths30
These functions are obtained by using multi-junction configurations that use p- and n-type semiconductors
with different band gaps and surface-bound electrocatalysts The brief description of PVs has been included
because they are an essential component for a number of systems that photocatalytically split water
Illustration
Figure 34 The illustration below shows a photoelectrochemical cell capable of water oxidation using solar energy consisting of
separated titanium dioxide (TiO2) and platinum (Pt) electrodes Water oxidation occurs at the TiO2 electrode where oxygen
is formed during which process protons (H+) and electrons (e
-) are released H
+ pass through an ion transport membrane to
a compartment containing the Pt electrode where electrons are used to reduce H+ to hydrogen After this hydrogen can be
stored as an energy source or it can be used to reduce carbon dioxide to higher order hydrocarbon compounds
Explanations
According to the National Renewable Energy Laboratory the greatest gains in efficiency have been made with
the multi-junction PV cells The first single-junction GaAs cells developed in the mid-1970s and had
efficiencies of ca 22 (which is better than most of the more recent PV cells that have been developed) The
most recent multi-junction technologies have achieved efficiencies of up to 46 It should also be noted that a
41
greater number of p-n junctions a PV has the greater its efficiency This is because each p-n junction is made
from a different semiconductor material that can absorb light at a different wavelength increasing the amount
of the spectrum that can be utilised PVs based on crystalline silicone cells have shown a slow increase in
efficiency over the last 40 years starting from 14 and increasing up to 276 PVs utilising thin-film
technologies now achieve efficiencies up to 223 Thin-film technologies are a particularly promising branch
of PV due to them being lightweight and the potential to manufacture them by printing which would decrease
their production and installation costs
Figure 3 shows a schematic diagram of a PEC cell that was developed by Honda and Fujishima in 1972 and
was capable of the water-splitting reaction using a TiO2 electrode in tandem with a platinum electrode61
PEC
cells consist of three basic components a semiconductor a reference electrode and an electrolyte The
principles of PEC cell operation are simple a photon is absorbed by the semiconductor (TiO2) material which
causes electron excitation and the excited electrons move to the reference electrode (Pt) through a metal
wire The movement of electrons between the two materials generates a positive charge (holes) at the
semiconductor which combines with electrons in the oxygen molecules of water to form molecular oxygen
and hydrogen ions At the reference electrode the electrons can combine with hydrogen ions to form
molecular hydrogen In this study oxygen was generated at the TiO2 electrode and hydrogen was generated at
the platinum electrode
Since the initial study by Honda and Fujishima researchers have spent much time developing new materials
for anodic and cathodic processes that are capable of carrying out the same process with greater efficiency
and ability to produce more products3061
Currently the cost-effectiveness of using solar energy systems to
generate power and fuels is constricted by the low energy density of sunlight which means low cost materials
need to be developed so that enough sunlight can efficiently be captured Sunlight availability is intermittent
which means that the captured energy needs to be efficiently stored The efficiency of PEC water-splitting
devices is determined by measuring their solar-to-hydrogen (STH) efficiency this is defined as the amount of
chemical energy produced in the form of hydrogen divided by the solar energy input without the use of any
external bias10
322 Current status review of the state of the art
Currently there are two main approaches that are used to photocatalytically split water into oxygen and
hydrogen The first method utilises a single-visible-light photocatalyst (this is essentially a PV) with a narrow
band gap capable of absorbing photons in the visible spectrum has a suitable thermodynamic potential for
water splitting and is stable enough to avoid photocorrosion4 The drawbacks of this system include that it is
only capable of utilising a small region of the spectrum and the collection of oxygen and hydrogen is difficult
due to them being produced in the same region2 The second method uses a two-step mechanism which
utilises two photocatalysts (photoanode and photocathode) in tandem similar to the Z-scheme present in
natural photosynthetic systems2 This setup enables the system to utilise a larger range of visible light
because the free energy required to drive each photocatalyst can be tuned compared to the one-step system
(one photon is needed for each photocatalyst) In this system the oxygen and hydrogen generated via water
oxidation can be separated more efficiently from each other because they are produced at different sites
(oxygen is produced at the anode and hydrogen is produced at the cathode) this also reduces the likelihood
of charge recombination462
This second system is more desirable as the oxygen and hydrogen evolution
sites can be contained in separate compartments62
Theoretical calculations have highlighted that the
maximum efficiency of a single absorber PEC system could reach 29-31 whereas a tandem PEC system
could reach 40-41 further highlighting the advantages of using tandem devices106364
Efficiency calculations
for three different PEC configurations a single photoabsorber system a dual stacked photoabsorber system
and a dual side-by-side photoabsorber system were reported to be 112 228 and 155 respectively
These systems differ in the spatial distribution and number of photoabsorbers which will affect the range of
wavelengths that can be absorbed and therefore the materialsrsquo STH efficiency10
It should be noted that the
practical efficiencies of these devices will often be much lower due to the inefficiencies associated with the
catalysts and reaction overpotentials10
These calculations show that the best way to achieve higher
efficiencies in PEC devices is to use a dual stacked photoabsorber system
42
Recently four PEC reactor types were conceived to represent a range of systems that could be used to
generate hydrogen from solar energy Each system design can be seen in Figure 31062
Types 1 and 2 are
based on relatively simple photoactive nanoparticle suspensions whereas types 3 and 4 are based on more
complex planar arrays a brief discussion of each system is given below It should be noted that quoted STH
efficiencies are optimised values and do not take into account material lifetimes
Figure 35 The figure below shows four PEC reactor types including a (a) Type 1 reactor showing the plastic bags containing the
suspended hydrogen- and oxygen-evolving photoactive particles (b) Type 2 reactor showing the plastic bags containing
separated suspensions of photoactive particles capable of separately evolving hydrogen and oxygen (c) Type 3 reactor
showing a sun-orientated panel containing a layered PEC cell capable of producing hydrogen and oxygen and (d) Type 4
reactor the design of which consists of a similar layered PEC cell to Type 3 with an added parabolic receiver that is able to
concentrate light onto the PEC cell throughout the day These figures were originally constructed by Pinaud et al 201310
Type 1 This reactor has the simplest design It consists of a transparent plastic bag that contains a
suspension of photoactive particles in 01 M potassium hydroxide that are capable of simultaneously
evolving hydrogen and oxygen by the water-splitting reaction Photons at a variety of different wavelengths
are able to penetrate the plastic bag whereas the electrolyte evolved gases and photoactive particles are
held within the bag The authors modelled the photoactive particles as spherical cores coated with
photoanodic and photocathodic particles The authors calculated that this reactor type could achieve a
realistic STH efficiency of 10 however it should be noted that the hydrogen and oxygen evolved in this
system would need to be separated1062
43
Type 2 The design of this reactor is very similar to that of Type 1 in that it consists of photoactive
nanoparticles suspended in an electrolyte contained within clear plastic bags The main difference
between the two systems is that the hydrogen- and oxygen-evolving particles are contained within
separate bags which reduces the need for a gas separation step and increases the safety of the system
However the bag design has to be more complicated in that a redox mediator is required along with a
porous bridge between the hydrogen- and oxygen-evolving bags The STH efficiency of this system was
calculated to be 51062
Type 3 This reactor is composed of a layered planar electrode consisting of multiple photoactive layers
(multi-junction PVsemiconductor) that is submerged within an aqueous solution containing 01 M
potassium hydroxide encased within a clear plastic case Multiple photoactive materials are used so that
more of the solar spectrum can be utilised The anode (oxygen evolution) is at the top of the cell where it
absorbs photons of a certain wavelength and allows others to pass through to the cathode where they are
absorbed into another layer to drive hydrogen evolution Due to the fixed orientation of these cells they
have to have a large surface area to ensure they can absorb the maximum amount of photons1062
Type 4 This reactor is similar to Type 3 in that it consists of a flat PEC cell of a similar design (gas
evolution occurs in a similar manner) The main difference is that a solar tracking concentrator system is
used to focus sunlight onto the PEC cell This means that smaller and more efficient PEC devices can be
used to reduce costs The STH efficiency of this system was calculated to 12-181062
The costs of hydrogen production for a power plant consisting of each reactor type were assessed (it should
be noted that costs for Type 3 and 4 plants were considered to be more accurate due to availability of PV
pricing)10
Type 1 $160 H2kg
Type 2 $320 H2kg
Type 3 $1040 H2kg
Type 4 $400 H2kg
During early work with PEC cells researchers were able to achieve efficiencies of 124 for hydrogen
production over 20 hours using a p-GaInP2(Pt)rsquoTJGaAs electrode However it should be noted that current
density decreased from 120 mAcm2 to 105 mAcm
2 over the course of the experiment which was caused by
damage to the PEC cell65
Therefore although this device was able to achieve high efficiencies its lifetime
was too low
Water oxidation in the presence of a photocatalyst that has been combined with a co-catalyst has been
reported2 The role of the co-catalyst is to provide extra reaction sites and decrease the activation energy for
oxygen and hydrogen evolution Researchers must carefully choose the type of co-catalyst to use this is
because although some noble metal catalysts like platinum and rhodium are good for enhancing hydrogen
production they also catalyse the reverse reaction (convert oxygen and hydrogen back to water)66
To
circumvent this issue transition-metal oxides are often used as co-catalysts instead of noble metals as these
do not catalyse water reformation However these compounds are often more susceptible to degradation
when they are exposed to the reactive environments found in PECs4
The first example of a metal oxide being used to split water into oxygen and hydrogen was carried out by a
dinuclear ruthenium complex (the blue dimer)34
Electrochemical and in situ spectroscopic measurements
were used to measure hydrogen production when platinum and rhodium plates deposited with chromia
(Cr2O3) were used as the water-splitting material4 Coreshell-structured nanoparticles that have a noble metal
or noble metal oxide core and a Cr2O3 shell have been shown to be capable of acting as a co-catalyst for the
water-splitting reaction This presents a mechanism by which noble metals could be used as co-catalysts the
Cr2O3 shell has been shown to supress the water reformation reaction when coated onto palladium and
platinum cores4 Multiple transition metal oxides such as NiOx RuO2 and TiO2 can be used as co-catalysts
when they are treated with appropriate chemicals (TRL 3-4)
44
Researchers recently reported a catalyst that was formed upon the oxidative polarization of an inert indium tin
oxide electrode immersed in a solution containing 100 mM potassium phosphate and 05 mM cobalt (II) ions at
pH 70 Upon initiation of electrolysis at 129 V oxygen production was shown to increase linearly over 12
hours to reach a maximum of 100 microM h-1
(after 12 hours electrolysis was stopped)67
The catalytic activity of
the reaction was also shown to be pH-dependent which suggests that the hydrogen phosphate ion is the
proton acceptor (TRL 3)
In a recent publication a multi-junction design was used to absorb light and provide energy for the water-
splitting reaction Multi-junction PVs are more efficient as they are able to absorb enough solar energy to
provide the free energy for water splitting The researchers developed a device based on an oxide
photoanode (Fe2O3 or WO3) and a dye-sensitized solar cell which performs unassisted water splitting with an
efficiency of up to 31 STH Incoming light was absorbed by the photoanode where the water-splitting
reaction and oxygen evolution takes place Electrons were transported to a platinum cathode where hydrogen
formation occurred68
(TRL 4)
Recently researchers demonstrated water splitting using tandem PEC cells where PtCdSCGSACGSe was
used as the photocathode (hydrogen evolution) and NiOOHFeOOHMoBiVO4 as the photoanode (oxygen
evolution) The cell was able to sustain a stable water-splitting reaction for 2 hours with an STH efficiency of
06769
(TRL 3)
Photochemical hydrogen production by nanowire arrays has been shown to be advantageous to more
traditional system designs because they use less precious material to produce7071
Researchers recently
showed that photoelectrochemical hydrogen production from water was possible using InP nanowire arrays In
these systems the chosen nanowire compound has a layer of silicone oxide (SiO2) deposited onto its surface
and then a co-catalyst deposited onto the surface of Efficiencies of 52 and 64 were obtained when the
InP nanowires were deposited with platinum and MoS3 respectively7072
Silicon is an abundant low-cost
semiconductor commonly used in PV devices and photoelectrochemical hydrogen generation at the
Sielectrolyte interface has been extensively studied for decades Hydrogen is evolved slowly at the
Sielectrolyte interface which has led to research efforts to modify the surfaces with electrocatalysts such as
platinum and ruthenium which are showing good activities and efficiencies71
(TRL 2-3)
323 Patents
Patents have been filed for systems based on nanoparticle suspensions and PECs some of which are
discussed below
A patent was filed in 2012 detailing a suspension of photoactive nanoparticles consisting of metallic cores and
semiconductor photocatalytic shells that can photocatalytically split water to directly obtain hydrogen The
efficient and unassisted photocatalytic splitting of water by the nanoparticles is based on resonant absorption
from surface plasmon in the metal coresemiconductor shell hybrid nanoparticles which can extend the
absorption spectra towards the visible-near infrared range This increases the solar energy conversion
efficiency When the photoactive nanoparticles are used in combination with scintillator nanoparticles the
hybrid photocatalytic nanoparticles can be used to convert nuclear energy into hydrogen73
(TRL 3-4)
A patent was recently filed for a PEC cell consisting of melanin melanin precursors melanin derivatives
melanin variants melanin analogues natural or synthetic pure or mixed with organic or inorganic compounds
metals ions drugs that act as the water electrolyzing material This technology uses solar energy as the sole
or main source of energy to produce hydrogen from water The system integrates a semiconductor material
and a water electrolyser inside a monolithic design that produces hydrogen directly from water using light
between 200 to 900 nm as the main or sole source of energy The technology aims to meet two criteria (i) the
system or light-absorbing compound should generate enough energy for the water-splitting reaction to be
45
completed and (ii) the materials need to be cheap to source and exhibit high stability in water and the reactive
environment The authors claim that all of these requirements can be met by melanin and related compounds
which represents a significant advancement in PEC design The technology can be used to generate
hydrogen oxygen and high energy electrons It can also be used to perform the opposite reaction and
generate water from electrons protons and oxygen and can be coupled to other processes generating a
multiplication effect It can also be used for the reduction of carbon dioxide nitrates and sulphates or others74
(TRL 2-3)
In 2008 a patent was filed describing a PEC system that could produce hydrogen from water The device was
comprised of (i) an electrolytic bath containing an electrode for catalytic oxidation an electrode for catalytic
reduction and an ion separation film disposed between the two electrodes immersed in an aqueous
electrolyte solution and (ii) a photoelectrode positioned outside the electrolytic bath and electrically connected
to the two electrodes This PEC system is characterised by disposing a photoelectrode at a position which
does not contact the electrolyte solution preventing the lowering of the photoelectrode activities and which
maximises hydrogen production efficiency75
(TRL 3)
In 2014 a patent was filed describing an invention that was able to generate hydrogen by
photoelectrocatalytic water splitting The system also incorporated an analysis-detection system The system
was composed of a photoelectrocatalytic water-splitting hydrogen generation device constructed from TiO2
nanorods (water splitting) a platinum cathode and a AgAgCl reference electrode submersed in a 05 M
Na2SO4 solution Results from five tests of the system were reported After the first hour the device produced
17-20 micromolh hydrogen for four hours as determined by the inbuilt detector76
(TRL 3)
324 Future development main challenges
The generation of electricity from solar energy by PVs has been successfully commercialised with the most
recent solar projects being able to produce electricity at a cost of 015 ndash 035 $kWh on a megawatt scale31
Facilities such as the Solar Star Power Station and the Topaz Solar Farm in the USA are examples of facilities
that use PV technologies that are capable of producing electricity (TRL 8-9) These facilities can now be
constructed because the cost of PVs has dramatically decreased and their efficiencies have increased over
the last few years Laboratory research is currently focused on further increasing the efficiency of PVs and
combining these systems with catalysts that are capable of generating higher order hydrocarbon fuels
However the reduction of carbon dioxide to liquid fuels is a complicated multi-electron process still in the
proof-of-concept stage (TRL 2-3) It is also recommended that the new materials PVs are constructed from
should ideally be cheap abundant lightweight flexible and robust If all of these requirements are met the
costs associated with manufacturing PVs as well as transporting installing and maintaining them may
continue to fall
There are a number of general challenges facing PEC technologies (including suspensions of photoactive
nanoparticles and PECs) that are associated with
Effectively designing facilities
Developing methods to store the generated energy
Developing transportation networks to distribute the energy
A major drawback of these facilities is that they can only be used during daylight hours when there is a clear
sky This highlights the importance of being able to store large amounts of energy at these facilities that can
be used outside of daylight hours It has been proposed that the energy generated from these facilities could
be stored in new types of batteries or as chemicals such as hydrogen and hydrocarbons Storing the energy
in the form of hydrocarbons would be particularly useful as these have a much higher energy density than
batteries and hydrogen The infrastructure to store and transport these already exists for them to be used as a
fuel However as previously mentioned the ability to convert hydrogen and carbon dioxide into high order
hydrocarbons using PVs and PECs is still in the proof-of-concept stage10
46
There are also a number of challenges related to the materials used to construct photoactive nanoparticles
and PECs This is particularly problematic because the most useful semiconductors are not stable in water
and the metal oxides that are stable in water often have band gaps that are too large for light absorption1065
There are three main processes that cause electrodes to degrade over long periods of time and inhibit their
activity
The first is corrosion which occurs with all materials over long periods of time
The second is catalyst poisoning which is caused by the introduction of solution impurities and it has
been shown that low concentrations of impurities can have a huge impact on electrode efficiency77
Finally changes to the composition and morphology (structurestructural features) of the electrode can
decrease their efficiency30
As well as exhibiting high stability the materials have to be highly efficient However there is a relationship
between device complexity cost and efficiency Water-splitters using triple-junction amorphous silicon or IIIndashIV
semiconductors have good efficiencies (5-10) but have high costs and device complexities Simpler
approaches using oxide-based semiconductors in a dual-absorber tandem approach have reported STH
conversion efficiencies up to 0368
This highlights the need to find cheaper and efficient semiconductor
materials that can be used for the water-splitting reaction
The US Department of Energy has determined that the price of hydrogen production delivery and dispensing
must reach $2-3 kg-1
before it can compete with current fuels2 It is also important to take into account the
infrastructural changes that would be required if we were to adopt a hydrogen fuel economy To meet the
current power demands of the US with PVs that have an efficiency of 10 a total area of 58000 miles2 would
be required The cost of semiconductors capable of these efficiencies amounts to tens of trillions of dollars
not taking into account the huge costs associated with the required changes to the infrastructure32
These
facilities would only be viable in areas where there is an abundance of sunshine (such as deserts) which also
proposes large fuel transportation issues In the majority of areas the sun is intermittent and only provides
about 6-10 hours of sunshine per day This further highlights the need to be able to store the energy in the
form of chemical bonds that can be used at any time as well as be more easily stored as batteries can only
store a relatively small amount of the energy required and can produce large quantities of toxic materials when
manufactured
It has been calculated that for the water-splitting reaction to provide one third of the energy required by the
human population in 2050 10000 solar plants each covering a 5 km x 5 km area (250000 km2 = 1 of the
Earthrsquos desert area) and with an overall efficiency of 10 would be required Each plant would be capable of
generating ca 570 tonnes of hydrogen from 5100 tonnes of water per day which together could provide up to
33 of the energy needed by mankind in 2050 The hydrogen could be transported directly to on-site
chemical plants where other organic compounds can be manufactured4 Figure 3 shows two diagrams of one
of these sites that could be capable of producing 570 tonnes of hydrogen per day24
The amount of each
material needed to generate methane from hydrogen and carbon dioxide is given in the formula below in
tonnes The US Department of Energy has set a target for hydrogen-producing PEC devices to have an STH
efficiency of 10 and a 5000 hour durability by 201878
120784119815120784 + 119810119822120784 rarr 119810119815120786 + 119822120784
120784(120784120790120787) + 120788120784120789120782 rarr 120784120784120790120782 + 120786120787120788
According to these calculations 6270 tonnes of carbon dioxide would be required by each of these plants per
day to use all of the hydrogen generated to produce 2280 tonnes of methane and 4560 tonnes of oxygen
The amount of carbon dioxide required increases linearly as the hydrocarbon chain length increases The cost
of manufacturing the number of PEC cells required to carry out this amount of water splitting would be in the
tens of trillions of euros taking into account the current costs of the associated technology62
The energy
required to power these facilities would be obtained from renewable sources such as wind wave and PVs
47
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting photoelectrochemical cells H2 generated
on-site could be used to reduce CO2 to higher order hydrocarbon fuel molecules These figures were constructed by Maeda
et al 2010 and Tachibana et al 2012
33 Co-electrolysis
331 Description of the process
Electrolysers capable of conducting the water-splitting reaction have existed for centuries Water electrolysers
are capable of converting water and DC electricity into gaseous hydrogen and oxygen according to the
equation below879
High-pressure (30 bar) water electrolysers have been commercially available since 1951
In 2012 there were at least 13 manufactures that produce low temperature water electrolysers (3 using
polymer electrolyte membranes (PEM) and 3 using alkaline electrolysers)79
Electrolysers that use solid oxide
electrolysers cells (SOECs) under high temperatures were first developed in the 1980s in the HotElly project
Currently SOEC technologies are still in the research and development stage It should also be noted that the
water splitting thermodynamics are more favourable at the higher temperatures used in SOECs as compared
to alkaline electrolysers PEMs and PECs ΔG = 237 kJ mol-1
(123 eV) at ambient temperatures ΔG = 183 kJ
mol-1
(095 eV) at 900 oC
8397980
120784119815120784119822 + 119811119810 rarr 120784119815120784 + 119822120784
Co-electrolysis is a technique that can be used to produce fuel molecules directly from electricity water and
carbon dioxide Interest in the electrolysis of water and carbon dioxide originated in the 1960s where it was
thought that the process could be used to supply oxygen for submarines and spacecraft81
Unlike electrolysis
co-electrolysis aims to simultaneously split water and reduce carbon dioxide to form a mixture of carbon
monoxide (CO) hydrogen and oxygen this process is highlighted in the equation below The term ldquosyngasrdquo
(synthesis gas) refers to a mixture of carbon monoxide and hydrogen and not the oxygen component
Producing fuels by co-electrolysis consists of three main stages carbon dioxide capture syngas synthesis
and storage of the renewable energy as chemical bond energy (hydrogen and hydrocarbon fuels)80
This
chemical reaction is achieved by using high temperature solid oxide cell electolysers3982-84
Co-electrolysis
offers a number of advantages over solar and wind power farms Solar and wind power farms have to be built
in site-specific areas to maximise their power output which limits the number of countries that would be able
to host these technologies (solar power is only viable for countries that have high levels of sun year-round)
Solar and wind power farms are only able to generate power intermittently which makes them unsuited to
coping with sudden large power demands (solar farms can only generate power during daylight hours) It has
been suggested that batteries and thermal fluids could be used to store energy for peak times However
48
these storage methods are currently unable to store large amounts of energy suffer from short lifetimes and
generate large amounts of harmful waste during production531
Technologies capable of co-electrolysing
water and carbon dioxide to syngas and hydrocarbons are at an early stage of development TRL 2-4
119810119822120784 + 119815120784119822 rarr 119810119822 + 119815120784 + 119822120784
It is also important to note that all electrolysers require a large input of electrical energy which would have to
be from renewable sources if this technology is to relieve its dependence on fossil fuels The major cost
associated with solid oxide electrolysis cells (SOEC) comes from the electricity required to operate them and
the feedstock while the cost of the electrolyser material makes up a smaller proportion of the total cost39
If
SOECs were designed to utilise wind and solar energy (PVssemiconductors) to generate the electricity they
require their operating costs would decrease significantly However this also decreases the number of
countries that could host electrolysers as their operation is again dependent on solar and wind energy It
would also be advantageous to incorporate a Fischer-Tropsch process that is capable of generating synthetic
hydrocarbons from the resulting syngas that can be used in the existing infrastructure3985
Syngas can be used to generate simple intermediate compounds that can be used as feedstock for more
complicated chemicals such as fertilisers pharmaceuticals plastics and synthetic liquid fuels Methanol is an
example of a simple molecule that can be made from syngas The dehydration of methanol can be used to
generate the cleaner fuel dimethyl ether which is being considered as a future energy source40
The most
common feedstocks for the production of hydrocarbon fuels are fossil fuels and biomass However it is hoped
that sustainable feedstocks such as carbon dioxide and water can be used to generate syngas which can be
converted into hydrocarbon fuels through Fischer-Tropsch synthesis39
Illustrations
Figure 37 A schematic diagram of water electrolysis being conducted in an alkaline electrolyser (left) and a polymer electrolyte
membrane electrolyser cell (right) to produce hydrogen and oxygen from water and DC electricity This figure was originally
produced by Carmo et al 20138
49
Figure 38 A schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell that produces hydrogen and
oxygen from water and DC electricity the reactions that occur at the electrodes are also shown This figure was adapted
from Meng Ni et al 20085
Explanations
Alkaline water electrolysis has been a mature technology for over 100 years (there were over 400 units in
operation by 1902) They have high efficiencies (47-82) and long lifetimes (15 years)1186
A recent
publication by Ursuacutea et al 2012 compiled a list of the main manufacturers of alkaline water electrolysers which
is shown in Table 3211
A number of advancements have been made regarding alkaline electrolysers over the last few years which
have focused on improving their efficiency to reduce operating costs and have increased the operating
current densities11
Other advancements include
Minimising the space between the electrodes to reduce the ohmic losses and allow the cell to operate at
current densities
Developing new materials to replace older diaphragms which exhibit higher stability and are better at
facilitating ion transport
Developing high-temperature (ca 150 oC) alkaline water electrolysers to increase the electrolyte
conductivity and promote the kinetics of the electrochemical reactions at the electrodesrsquo surface
Developing new electrocatalytic materials to reduce the electrode over-potentials this present a particular
difficulty for the anode because the oxidation half-reaction is most demanding
Alkaline electrolysers (Figure 3 left) consist of two electrodes that are separated by a gas-tight diaphragm
submersed in an electrolyte solution containing a high concentration of potassium hydroxide (20-30 wt) It
should be noted that electrolytes such as sodium hydroxide and sodium chloride can also be used in some
systems and they usually operate between 40-90 oC
11 Water is reduced at the cathode to generate hydrogen
gas and hydroxide ions (OH-) which diffuse through the diaphragm to the anode where they recombine to
generate oxygen and water811
The hydrogen and oxygen produced by alkaline electrolysers have purities
gt99
In PEM electrolysers (Figure 3 right) the electrolyte is constructed from a polymeric membrane with a cross-
linked solid structure permitting a compact system with greater structural stability (able to operate at higher
temperatures and pressures)8 The electrodes used in PEM electrolysers are usually constructed from noble
metals such as platinum and iridium which limits the scope of this technology as noble metals are of limited
abundance and expensive The unit consisting of the electrodes and polymer membrane is submersed in
water Water oxidation occurs at the anode where oxygen is formed and protons are transferred through the
50
polymer membrane to the cathode where they are reduced to hydrogen PEM electrolysers are able to
produce hydrogen and oxygen of even higher purity than alkaline electrolysers at ca 9999
It should be noted that the materials needed for the electrolyte and electrodes have to be cheap and easy to
manufacture on a large scale5 Water in the gas phase diffuses into the porous cathode where it dissociates
into hydrogen and oxygen at reaction sites81
At this point the hydrogen diffuses out of the cathode and is
collected The oxygen ions are transported through the electrolyte solution to the porous anode where they
are oxidised to oxygen and collected this process is demonstrated in Figure 35 The material chosen for the
cathode has to be able to support the diffusion of steam the reduction of steam and the diffusion of hydrogen
These requirements limit the number of suitable materials that can be used to noble metals such as platinum
and gold and non-precious metals such as copper and nickel However like the artificial photosynthetic
systems previously discussed the use of noble metals is unfavourable due to their rarity and high costs The
anode has to be chemically stable under similar conditions to the cathode which means that noble metals are
again candidate materials along with electronically-conducting mixed oxides5
Electrolyte This must be a chemically stable dense gas-tight material with good ionic conductivity and
low electronic conduction The electrolyte has to be stable enough to withstand the high temperatures
associated with the chemical reactions taking place It has to be gas-tight to limit the recombination of
protons and O- to hydrogen and oxygen respectively The electrolyte should also be as thin as possible so
as to minimise the ohmic overpotential5
Electrodes It should be noted that the following properties are the same for both the anode and cathode
The electrodes have to be porous enough to allow the transportation of hydrogen and oxygen and need to
have a similar thermal expansion coefficient to the electrolyte so as to limit the amount of mechanical
stress the components exert on each other They must also be chemically stable in highly
oxidisingreducing environments and high temperatures5
To ensure that the SOEC is operating at its maximum efficiency a number of parameters need to be
quantified this is often done through modelling the system Some of the parameters measured include the
composition of the cathode inlet gas cathode flow rate and cell temperature39
When generating syngas in a
SOEC the carbon dioxide is fed into the cathode side of the device where the hydrogen is generated
51
Table 32 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the performance data for each device This table was originally constructed by Ursua et al 201211
Manufacturer
Technology
(configuration)
Production
(Nm3h)
Rated Power
(kW)b
Energy
Consumption
(kWhNm3)c
Efficiency
()d
Maximum
Pressure
H2 purity
(vol)
Location
AccaGen Alkaline (monopolar) 1-100 67-487 6-487 528-727 10 999 Switzerland
Avalance Alkaline (bipolar) 04-36 2-25 543-5 652-708 448 na USA
Claind Alkaline (bipolar) 05-30 na na na 15 997 Italy
ELT Alkaline (bipolar) 3-330 138-1518 46-43 769-823 1 998-999 Germany
ELT Alkaline (bipolar) 100-760 465-3534 465-43 761-823 30 993-998 Germany
Erredue PEM (bipolar) 06-213 36-108 6-51 59-698 25-4 993-998 Italy
Giner Alkaline (bipolar) 37 20 54 655 85 na USA
Hydrogen Technologies Alkaline (bipolar) 10-500 43-2150 43 823 1 999 Norway
Hydrogenics PEM (bipolar) 10-60 54-312 54-52 655-681 10 999 Canada
Hydrogenics Alkaline (bipolar) 1 72 72 492 79 9999 Canada
H2 Logic Alkaline (bipolar) 066-4262 36-213 545-5 649-708 4 993-998 Denmark
Idroenergy Alkaline (bipolar) 04-80 3-377 75-471 472-752 18-8 995 Italy
Industrie Haute Technology Alkaline (bipolar) 110-760 5115-3534 465-43 761-823 32 998-999 Switzerland
Linde Alkaline (bipolar) 5-250 na na na 25 999 Germany
PIEL division of ILT Technology Alkaline (bipolar) 04-16 28-80 7-5 506-708 18-8 995 Italy
Proton OnSite PEM (bipolar) 0265-30 18-174 73-58 485-61 138-15 99999 USA
Sagim Alkaline (bipolar) 1-5 5-25 5 708 10 999 France
Teledyne Energy Systems Alkaline (bipolar) 28-56 na na na 10 99999 USA
Tredwell Corporation PEM (bipolar) 12-102 na na na 75 na USA
52
332 Current status review of the state of the art
This section will focus on the advancements that have recently been made in regards to SOECs Much of the
research being conducted on SOECs is focused on increasing the efficiency and stability of the electrolyte and
electrodes by changing the temperature the SOECs operate at gas mixtures and the materials the cells are
constructed from
The most common electrolyte material used in SOECs yttria-stabilised zircona (YSZ) due to it having a high
thermal stability high oxygen ion conductivity and low cost To generate YSZ zirconia (ZrO2) can be doped
with compounds such as Y2O3 and Yb2O3 to improve the stability and conductivity Sc2O3 can also be used to
generate scandia-stabilised zirconia (ScSZ) Other co-dopants such as TiO2 and Al2O3 can be added to
further enhance the stability587
Scandium stabilised zirconia (ScSZ) has a higher conductivity than YSZ but
is not as widely used due to the high costs associated with it It should also be noted that the dopant
concentration has to be of a specific amount in order to ensure the conductivity is at its maximum It has been
shown that different dopant concentrations change the lattice structure of the ZrO2 over time which leads to
the decrease in conductivity5 The dopant chosen for the SOEC is also dependent on the temperature the cell
will have to operate at as the dopant will change the conductivity of the electrolyte at different temperatures
Researchers recently investigated the effect temperature (550 oC ndash 750
oC) had on the performance of SOEC
cells with the following layout a Ni-YSZ support layer (680 microm) a Ni-ScSZ cathode-active layer (15 microm) a
ScSZ electrolyte layer (20 microm) and a LSM-ScSZ anode layer (15 microm) The performance of the cell was
observed to decrease with decreasing temperature when the same gas composition was used (143 CO
286 H2O and 571 Argon) As the temperature decreased the ionic conductivity of the electrolyte layer
decreased The mass transfer was the rate-determining step for the electrodes at temperatures lt750 oC
Methane was only detected in the gas products when the input gas composition was the same as above the
cell temperature was lt700 oC and the operating voltage was gt 2 V
81 (TRL 3)
Electrolyte materials such as ceria- and LaGaO3-based electrolytes are showing promise at intermediate
temperatures when they are doped with other compounds that increase their ionic conductivity79
Recently
researchers developed SOEC capable of steam and carbon dioxide co-electrolysis The cell was constructed
from Ni-YSZ (nickel-yttria-stabilized zirconia) solid oxide cell with a bi-layered ScSZGDC electrolyte structure
and a LSCF (lanthanum strontium cobalt ferrite) oxygen electrode When the device was operated at 800 oC
the cell exhibited a high electrolysis current density of about 22 A cm2 and 19 Acm
2 in steam and carbon
dioxide electrolysis respectively The structural integrity of the cell was checked after the experiment and no
cracking or delamination of the electrolyte or the electrolyteelectrode was observed88
(TRL 4)
Researchers were recently able to directly synthesise methane by co-electrolysing carbon dioxide and water
to form carbon monoxide and hydrogen then conducting Fischer-Tropsch synthesis in tubular solid oxide
electrolysis cells7 As previously discussed the reduction of water in SOECs requires very high temperatures
(ca 800 oC) however with the Fischer-Tropsch process lower temperatures (ca 250
oC) are required Using
the experimental setup shown in Figure 3 researchers were able to achieve a methane yield of 1184
which means that 41 of carbon dioxide is converted to methane over the course of the 24-hour test7 The
equipment consists of a SOEC tube with a hole running through its length while the wall of the tube consists
of three layers that are structured in a similar fashion to that shown in Figure 3 it consists of an anode an
electrolyte and a cathode The first section of the SOEC tube is heated to 800 oC to allow syngas to be
generated after which the tube cools over a gradient to 250 oC to allow methane production to take place
(TRL 4)
53
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis cell electrolysers This table
was originally constructed by Carmo et al 20138
Alkaline Electrolysis PEM Electrolysis SOEC Electrolysis
Advantages
Well-established technology High current densities Efficiency up to 100
Non-noble metal catalysts High voltage efficiency Efficiency gt 100
Long-term stability Good partial load range Non-noble metal catalysts
Relative low cost Rapid response system High pressure operation
Stacks in the megawatt range Compact system design
Cost effective High gas purity
Dynamic operation
Disadvantages
Low current densities High cost of components Laboratory stage
Crossover of gases Corrosive environment Bulky system design
Low partial load range Low durability Low durability
Low dynamics Stacks below megawatt range Little costing information
Corrosive electrolyte
Figure 39 A schematic diagram of co-electrolysis and the Fischer-Tropsch process being conducted in a tubular solid oxide
electrolyser that is able to produce CH4 This figure was originally generated by Chen et al 20147
333 Patents
The cell was composed of separate anode and cathode chambers separated by a membrane that allows the
transport of sodium ions (Na+) the anode and cathode chambers are in contact with water Oxygen is
collected in the anode chamber and hydrogen is collected in the cathode chamber following which hydrogen
and carbon dioxide are reacted together to generate syngas and oxygen as by-products that need to be
separated The electrode materials were described as being ceramic that could be doped with a catalyst
material such as cobalt cerium europium or cadmium combinations of these elements were also permitted89
(TRL 3)
A patent was filed in 2011 detailing a design for SOEC that could co-electrolyse steam and carbon dioxide to
produce syngas The cell consisted of a cathode composed of nickel-zirconia an anode consisting of
strontium doped lanthanum manganite and the electrolyte between the two electrodes was composed of
yttria-stabilised zirconia the whole cell was designed to operate between 800-1000 oC The authors stated
that the electrical power to run the device would be sourced from nuclear power however it should also be
possible to run this device off solar energy This device operated with the carbon dioxide being fed into the
cathode section where the hydrogen is generated90
(TRL 4)
54
A patent was filed in 2013 detailing a modified anodeelectrolyte structure for a solid oxide electrochemical
cell where the role of the anode is to react with fuel (steamhydrocarbons) The cathode (when in SOEC
mode) consisted of a backbone of electronically conductive perovskite oxides selected from the group
consisting of niobium-doped strontium titanate vanadium-doped strontium titanate and tantalum-doped
strontium titanate mixtures were also permitted The electrolyte material consisted of a scandia and yttria-
stabilised zirconium oxide91
(TRL 2-3)
334 Future development main challenges
Technologies that are capable of electrolysing water cover a variety of TRLs wherein alkaline and PEM
electrolysers used to generate hydrogen by the water-splitting reaction have TRLs 7-8 as they have been
commercialised can be purchased and can produce power at the low megawatt scale However they are
currently not a viable option to generate power at the megawatt scale Newer SOEC technologies currently
being developed have lower TRLs (3-5) but are showing great promise in that their efficiencies are high and
they are cheap to produce
Technologies capable of co-electrolysing water and carbon dioxide to syngas are at an early stage of
development - TRLs 2-4 Research is still focused on studying how cell conditions can be manipulated to
optimise the production of syngas and hydrocarbons Research is also focused on improving the long-term
stability of the electrolytes and electrodes used in SOECs by investigating new materials and cell designs that
are cheap and easy to construct It will also be necessary to conduct duration experiments In terms of their
commercial viability they are far behind PVs at roughly the same stage as PEC technologies and ahead of
synthetic biology systems
SOECs could prove to be an efficient method by which electrical energy generated from renewable sources
(wind and solar) could be stored in the form of chemical bonds To date it has been proven that syngas can
be generated from SOECs and that methane can also be generated within the same system through a
Fischer-Tropsch process More research is needed that aims to improve the efficiency by which methanol can
be generated and to determine whether more complex hydrocarbons can be synthesised
The success of this technology is likely to be dependent on how well systems that generate electricity from
renewable sources can be integrated within it It has been suggested that nuclear wind and solar power
stations could be used to provide the electrical power required This would help to lower the cost of this
technology as sourcing the electricity needed is one of the major costs It should be noted that one of the
most commonly cited advantages of this technique over solar and wind power is that it is not site-specific
However if solar and wind power were to be used to generate the electricity needed for this technology then
it becomes a site-specific technology again This is also a problem for PEC-cell-based technologies
34 Summary
The aim of this brief literature review was to highlight the advancements that have been made across the main
technologies within artificial photosynthesis discuss some of the most recent technological solutions that have
been developed in these areas and identify the main challenges that need to be addressed for each
technology before they can be commercialised
Synthetic biology amp hybrid systems
Synthetic biology amp hybrid artificial photosynthetic systems are currently capable of producing small amounts
of fuel molecules such as hydrogen and simple hydrocarbons The majority of the technologies in this
category are at the research and development stage (TRL 1-4) To date there are no large scale plans to
produce solar fuels at a commercial level using this technology It should be noted that synthetic biology amp
hybrid systems are currently used to produce fine chemicals at the commercial level but these are not needed
55
in the large quantities in which solar fuels are required It is currently too early to comment on the long-term
commercial viability of this technological pathway however the research in this area is progressing quickly
and as our fundamental understanding of biological systems increases progression is promising It should be
noted that these systems are becoming efficient enough to produce hydrogen at a rate that is comparable to
that which occurs in natural photosynthesis on a small laboratory scale
Photoelectrocatalysis of water (water splitting)
PVssemiconductors are the most advanced technology discussed in this report as they have been
commercialised and are able to generate electricity on a MW scale at facilities such as the Solar Star Power
Station and the Topaz Solar Farm31
PVssemiconductors are used in PEC technologies where they are
incorporated into the cell design and act as light absorbers Instead of the energy gained from light absorption
being used to generate electricity directly it is used to generate fuel molecules such as hydrogen from the
water-splitting reaction The hydrogen generated from this process can then be stored and used at a later time
to provide energy This is useful because PVs are only able to generate power intermittently during daylight
hours There are many examples of photoelectrocatalysis being carried out by PECs as well as suspensions
of photoactive nanoparticles and the majority of the technologies have a TRL 2-4 However it should be noted
that PVsemiconductor technologies that generate electrical power have TRL 8-9 The main challenges facing
this technology involve developing materials that have high STH efficiencies are cheap to manufacture and
are stable for long periods of time Calculations have been performed to determine the efficiencies associated
with multiple reactor plant designs These have shown that it is theoretically possible to generate large
quantities of hydrogen however that it could cost trillions to generate a significant amount of hydrogen with
current technology
Co-electrolysis
Water electrolysers such as alkaline and PEM electrolysers are considered mature technologies that have
been commercialised and have TRLs 7-8 They can be purchased and can produce power at the low
megawatt scale However they are currently not a viable option to generate power at the megawatt scale
Newer SOEC technologies that are currently being developed have lower TRLs 3-5 but are showing great
promise in that their efficiencies are high and they are cheap to produce Technologies that are capable of
generating syngas and some organic products by a Fischer-Tropsch process are in the research and
development stage (TRL 3-4) Research is currently focused on determining how SOEC conditions can be
manipulated to increase efficiency as well as identifying more stable durable and efficient compounds to
incorporate into the cell design The incorporation of SOECs into large scale solar and wind farms could prove
to be an efficient method by which electrical energy can be stored as chemical energy
The technologies discussed above show great potential in being able to convert solar energy into solar fuels
They are still in the early research phase but all technologies made significant improvements in efficiencies
lifetimes and the number of products they can produce other than hydrogen It is likely that PVs will be used to
absorb solar energy to generate electricity for SOECs or forms part of a PEC cell that generates fuel
molecules It should be noted that wind power could be used to provide the electricity needed for SOECs to
operate which would allow these systems to be used outside of desert regions Biological systems currently
look to be less suitable for producing large quantities of fuel molecules partly due to their early research stage
but may prove to be useful in generating highly complicated molecules once the understanding of protein
engineering has increased
All of these technologies seek to improve device lifetimes increase efficiency lower manufacturing costs and
increase the scope of synthetic fuels that can be produced Switching to a hydrogen economy will require
large and expensive infrastructure changes Using hydrogen to generate more complex fuel molecules will
require more research however ultimately fewer infrastructure changes
57
4 Mapping research actors
41 Main academic actors in Europe
In Europe research on AP is conducted by individual research groups or in research networks or consortia
Most of the research groups are located in Germany the Netherlands and Sweden The largest country-based
networks are also in Sweden and in the UK Most of Germanyrsquos research groups are part of the pan-European
AP network AMPEA The number of research groups has increased substantially since the 1990s when the
field became more prominent coupling with the (exponential) rise of publications in AP3
411 Main research networkscommunities
In this section we describe the main research networkscommunities on artificial photosynthesis in Europe
Under networks we indicate co-operations with multiple universities research organisations and companies
Instead of focusing strictly on major integrated research on specific AP topics the networks mostly have a
broad research and collaboration focus Larger joint programmes exist but are more focused on various key
priorities in Europe for different research areas such as AMPEA (Advanced Materials and Processes for
Energy Application) which is one of the joint programmes of EERA (European Energy Research Alliance) of
which artificial photosynthesis is one of the three identified applications The first national research network
dedicated to artificial photosynthesis was the Swedish Consortium for Artificial Photosynthesis (CAP)
following which a number of other national and pan-European networks emerged in the past few years
Research networks and communities play an important role in facilitating collaboration across borders and
among different research groups The development of AP processes needs expertise from molecular biology
biophysics and biochemistry to organometallic and physical chemistry Research networks provide the
platform for researchers and research teams from those diverse disciplines to conduct research together to
create synergistic interactions between biologists biochemists biophysicists and physical chemists all
focusing on questions relevant for AP and solar fuels This need for research coordination is reflected by the
fact that the Swedish Consortium for AP was a bottom-up initiative by university-based scientists4
Furthermore networks are effective for promoting AP research and raising public awareness and knowledge
about AP5
Networks and consortia with industrial members also play an important role with respect to the goal of turning
successfully developed AP processes into a commercially viable product Research and innovation in
materials and processes of AP can be backed up by private innovation and investments Feedback on the
applicability of research outputs can be incorporated and shape further research efforts and application
possibilities in the business sector can be discovered
The advantages and synergy effects of network membership for research groups are reflected in the fact that
more than 50 of European research groups are part of a research network in Europe The consortia vary in
their membership and their funding sizes whereas about 400 researchers are affiliated with the pan-European
consortium AMPEA the Swedish CAP unites about 80 scientists Furthermore it is apparent that only AMPEA
is a truly pan-European consortium member research groups come from various European countries such as
Austria France Czech Republic Germany Italy the Netherlands Norway Spain Sweden Switzerland and
3 V Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in
ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press) conducted a bibliometric analysis using key words related to the field of artificial photosynthesis showing that only a few papers were published before the 1990s reaching more than 900 publications in 2014
4 httpwwwsolarfuelse
5 httpsolarfuelsnetworkcomoutreach
58
the UK Most of the other consortia discussed below are based in a specific country which is reflected in their
affiliations among research groups
EU - AMPEA
The European Energy Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials
amp Processes for Energy Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging
Technologies and artificial photosynthesis became the first energy research subfield to be organised within
AMPEA The goal of this joint programme which was launched at the end of 2011 is to set up a thorough and
systematic programme of directed research which by 2020 will have advanced to a point where commercially
viable artificial photosynthetic devices will be under development in partnership with the industry Its goal to
boost research on a pan-European basis is reflected in the fact that to date more than 40 European scientific
institutions participate Many institutes in different Member States are associated with AMPEA (31 full
members for example CEA DIFFER TU Delft JKU Max Planck Institute)6 The research efforts of the
AMPEA participants aim at advancing all of the three identified pathways of artificial photosynthesis Due to
the low availability of efficient molecular catalysts based on earth-abundant elements the search for those
elements and the development of such catalysts constitute the early research focus
Italy ndash SOLAR-CHEM
In 2009 the universities of Bologna Ferrara and Messina founded SOLAR-CHEM the Italian inter-university
centre for the chemical conversion of solar energy7 Later on other universities in Italy also joined SOLAR-
CHEM The research efforts of the centre aim to foster research in solar fuels through a multidisciplinary
approach and coordination activities eg through the organisation of dedicated events and through short-term
exchanges of staff in the network
Netherlands ndash BioSolar Cells
The Dutch BioSolar Cells public-private partnership was established in 2010 BioSolar Cells is a cooperation
of 10 knowledge institutions such as Leiden University Delft University of Technology and the University
of Twente8 as well as 45 private industries
9 The programme is funded by FOMALWNWO the Dutch
ministry of Economic Affairs Agriculture and Innovation many companies and a number of Dutch universities
and research organisations The BioSolar Cells programme has three themes artificial photosynthesis
photosynthesis in cellular systems and photosynthesis in plants These three research themes are
underpinned by a fourth theme education and societal debate where educational modules are developed to
equip and inspire future researchers policy makers and industrialists and where the societal consequences
of new solar-to-fuel conversion technologies are debated10
Sweden - CAP
Founded in 1994 the Swedish Consortium for Artificial Photosynthesis carries out integrated basic
research with the goal to produce applicable outcomes such as fuel from solar energy and water Their
projects integrate two topics artificial photosynthesis in man-made systems to make hydrogen from sun and
water and photo-biological fuel production in living organisms They focus on photoelectrocatalysis as the
technology pathway yet are also building on their research on the principles of natural photosynthesis for
energy production A unique component in the consortium is hence the synergistic interactions between
biologists biochemists biophysicists and physical chemists all focusing on questions relevant for solar
fuels11
The academic partners come from Uppsala University Lund University and the KTH Royal
Institute of Technology in Stockholm
6 httpwwweera-seteueera-joint-programmes-jpsadvanced-materials-and-processes-for-energy-application-ampea
7 httpswwwsocchimitsitesdefaultfileschimindpdf2012_6_88_capdf
8 httpwwwbiosolarcellsnlover-biosolar-cellsnew_page_1html
9 httpwwwbiosolarcellsnlover-biosolar-cellsbedrijvenhtml
10 httpwwwbiosolarcellsnlonderzoek
11 httpwwwsolarfuelsesolar-fuels
59
UK ndash SolarCAP
The SolarCAP Consortium for Artificial Photosynthesis is a consortium of four UK academic research groups
funded by the Engineering and Physical Sciences Research Council The groups based in the Universities
of East Anglia Manchester Nottingham and York12
are specifically exploring the solar conversion of
carbon dioxide to carbon monoxide in tandem with the conversion of methane or alkanes to useful oxygen-
containing products such as alcohols They are exploring the second technological pathway of
photoelectrocatalysis
UK ndash Solar Fuels Network
Solar Fuels Network brings together academic and industrial researchers in solar fuels and artificial
photosynthesis It aims to develop an effective community of solar fuels researchers from both academia and
industry to raise the profile of the UK solar fuels research community nationally and internationally Through
this it aims to promote collaboration and co-operation with other research disciplines industry and
international solar fuels programmes and to contribute towards the development of a UK solar fuels
technology and policy roadmap The networkrsquos management team is based at Imperial College London and
is led by Prof James Durrant Partner organisations encompass the Royal Society of Chemistry the Energy
community of the Knowledge Transfer Network (KTN) the Solar Fuels Institute (SOFI) and the Foreign and
Commonwealth Officersquos Science and Innovation Network13
In other countries across Europe national initiatives have emerged in the last few years and more are
expected to in the future For example the Photoelectrochemistry Competence Center (PECHouse and
PECHouse2)14
under coordination of the Ecole Polytechnique Federale de Lausanne (prof Michael Graumltzel)
has been created in Switzerland while in France artificial photosynthesis is being researched by laboratories
of excellence (LabEx Arcane15
and LabEx Charmatt16
)
412 Main research groups (with link to network if any)
A list of the main research groups in Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire Artificial
Photosynthesis community Taking that into account the numbers presented below may provide an indication
of the AP research sector as a whole
Table 41 Number of research groups and research institutions in European countries
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Austria 1 1 15
Belgium 1 1 -
Czech Republic 1 1 -
Denmark 3 2 -
Finland 1 1 6
France 5 3 14
Germany 31 17 16
Ireland 1 1 7
Italy 5 5 29
Netherlands 28 9 18
Norway 1 1 -
12
httpwwwsolarcaporgukresearchgroupsasp 13
httpsolarfuelsnetworkcommembership 14
httppechouseepflchpage-32075html 15
httpswwwlabex-arcanefrencontentlaboratoires-excellence-arcane 16
httpwwwcharmmmatfrindexphp
60
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Spain 4 4 11
Sweden 13 5 17
Switzerland 5 5 10
UK 13 9 10
Total 113 65 15
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 66 main research institutions and universities working on artificial photosynthesis in Europe
Those research institutions contain 113 individual research groups with an average size of about 15
people17
The sizes of research groups can vary widely from for example 80 members of a research group at
Imperial College London to only two persons in the research group of Klaus-Dieter Weltmann at the Leibniz
Institute for Plasma Science and Technology The country with both the highest number of involved institutions
and research groups is Germany where 32 individual research groups in 17 research institutions are active
Germany is followed by the Netherlands with nine institutions and 28 research groups and by Sweden with
five institutions and 13 research groups Almost half (47) of the research groups focus on the second
pathway ie photoelectrocatalysis whereas 36 research the first pathway ie the usage of synthetic
biology and hybrid systems to produce fuel molecules and about 17 follow the third pathway in their
research which is co-electrolysis A bulk of the research in most countries is done on the second pathway
except for in Sweden and Finland which seem to specialize in exploring the first pathway Table 42 provides
an overview of some of the key statistics the number of research groups and research institutions in AP per
country and the number of research groups focusing on each of the three technological pathways
respectively
Table 42 Number of research groups per research area (technology pathway)
Country Total Synthetic biology
amp hybrid systems
Photoelectrocatalysis Co-electrolysis
Austria 1 1 1 0
Belgium 1 1 1 0
Czech Republic 1 0 1 0
Denmark 3 0 2 2
Finland 1 1 0 0
France 5 2 5 0
Germany 31 14 15 9
Ireland 1 1 1 0
Italy 5 0 5 0
Netherlands 28 12 17 9
Norway 1 0 1 0
Spain 4 2 3 1
Sweden 13 10 7 0
Switzerland 5 1 5 3
UK 13 8 5 1
Total 113 53 69 25
Source Ecorys
17
The average group size is derived from survey responses and available information on the websites of the groups
61
In the following section our findings have been illustrated by presenting some of the main research institutions
and their research groups
Germany - Helmholz Zentrum Berlin
The Institute for Solar Fuels of the HZB is led by Prof Roel van de Krol The institute pursues a strategy to generate
hydrogen via the second technology pathway they combine the energy conversion of light into electrical energy via
photonic stimulation of the semiconductor directly with the catalytic procedures on the electrolyte-electrode-interface for
the conversion into storable chemical energy (hydrogen) The generated hydrogen can then be stored by means of
already known methods (compressed gas liquid-H2 metal hydride conversion to methanol) Their approach combines
research and insights from photo-physics surface- and material chemistry photoelectrochemistry interface- and
surface sciences as well as system alignment18
Therefore they collaborate closely with the University of Messina in
Italy and the Leiden University in the Netherlands Moreover the HZB is also part of the European research network
AMPEA
Germany ndash Max Planck Institute for Chemical Energy
The Department of Biophysical Chemistry at the Max Planck Institute for Chemical Energy focus on the water-oxidizing
enzyme of oxygenic photosynthesis and hydrogenases Their research uses a variety of different physical techniques
to gain insight into enzymatic processes such as into photosynthetic water splitting and (bio)hydrogen production
which can be used for biomimetic chemistry ie to develop catalytic systems in energy research19
They hence focus
on the first and second technology pathways The Max Planck Institute for Chemical Energy also contributes to the
European research network AMPEA
The Netherlands - The Dutch Institute for Fundamental Energy Research
Part of the Netherlands Organisation for Scientific Research (NWO) the DIFFER institute has since its initiation in 2012
grown to an activity of about 65 Meuroyear (about 75 fte) all directed at the production of chemicalsfuels from electrons
and photons In particular as part of its solar fuels research DIFFER investigates the splitting of water into hydrogen
and oxygen using electricity and the reduction of carbon dioxide to carbon monoxide As they are located at TUe
campus in Eindhoven they can easily collaborate and share knowledge with universities universities of applied
sciences and industry The DIFFER institute also contributes to AMPEA
Sweden ndash Uppsala University
Various research teams at Uppsala University cover all three relevant technology pathways for artificial
photosynthesis20
Moreover in 2006 the Swedish Consortium for Artificial Photosynthesis (CAP) founded in 1994 by
three researchers from Uppsala University and one researcher from the University of Stockholm created a new
scientific environment at the Aringngstroumlm laboratory at Uppsala University becoming the base for this consortium
Switzerland ndash ETH Zurich
The Professorship of Renewable Energy Carriers21
performs RampD projects in emerging fields of renewable energy
engineering operates state-of-the-art experimental laboratories offers advanced courses in fundamentalapplied
thermal sciences and produces qualified scientists and engineers with expertise in renewable energy technologies
Regarding solar fuels they focus on solar splitting of H2O and CO2 via thermochemical Redox cycles which
corresponds to the third technology pathway of artificial photosynthesis They are partners in several EU projects
concerning solar-driven hydrogen production such as SOLARJET ndash Solar Production of Jet Fuel from H2O and CO2
and HYCYCLES ndash Solar Water-Splitting Thermochemical Cycle22
18
httpswwwhelmholtz-berlindeforschungoeeesolare-brennstoffeindex_enhtml 19
httpwwwcecmpgderesearchbiophysical-chemistryoverviewhtmlL=1 20
httpwwwkemiuuseresearchmolecular-biomimeticphotosynthesis 21
httpwwwprecethzch 22
httpwwwprecethzchresearchsolar-fuelshtml
62
UK ndash Imperial College London
The research of various research teams of the Imperial College London encompasses the first and second technology
pathways It ranges from research on the oxidising enzyme Photosystem II which has become the focus of attention
because cheap water-splitting catalysts are urgently needed in the energy sector to the development of
photoelectrodes and nanoparticles for solar-driven fuel synthesis based on water splitting of water into hydrogen and
oxygen Collaborations across the Imperial College London are complemented with co-operations across the UK as
part of the UK Solar Fuels Network with the Swiss Federal Institute of Technology in Lausanne (EPFL) UCL and
Cambridge University
The density of research group per country in Europe is presented schematically in Figure 41
Figure 41 Research groups in Artificial Photosynthesis in Europe
Source Ecorys
42 Main academic actors outside Europe
Also outside of Europe research on AP is conducted by individual research groups or in research networks or
consortia Most of the research groups and networks are located in the US and in Japan Whereas US-based
networks sporadically have ties to European research groups the Japanese consortia have exclusively
Japanese members both academic and industrial
421 Main research networkscommunities
Outside of Europe the main networks can be found in the US and in Japan The biggest network is the US
network JCAP (Joint Center for Artificial Photosynthesis) with more than 190 persons linked to the
programme and a budget of $122 million for five years Next in line is the Japanese ARPChem which has
roughly the same budget available for a time span of 10 years
63
Japan ndash ARPChem
The Japanese Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology jointly launched the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem) in November 2012 The aim is to bundle efforts for the next
decade to develop innovative catalysts and other materials that could be used for manufacturing fundamental
chemical substances from water and carbon dioxide by making use of solar power Such substances can be
used as raw materials of plastics synthetic fibres synthetic rubber solvents and other products and are
applicable in all areas of peoples everyday lives The expected budget for the coming decade between 2012
and 2021 amounts to 15 billion yen (euro 122 million)23
The utilisation of catalyst technology requires long-term
involvement and entails high risks in development but is expected to have a huge impact on Japans
economy and society The aim is to achieve independence from fossil resources used as raw materials for
chemical substances while overcoming resource and environmental challenges The consortium consists of
partners from academia industry and the government seven universities amongst them the University of
Tokyo the Tokyo University of Science and the Kyoto University companies such as Mitsubishi
Chemicals Mitsui Chemicals Fuji Films and TOTO and governmental research organizations such as the
National Institute of Advanced Industrial Science and Technology (AIST)
Japan ndash All Nippon Artificial Photosynthesis Project for Living Earth (AnApple)
The All Nippon Artificial Photosynthesis Project for Living Earth (AnApple) is one of the Scientific
Researches on Innovative Areas receiving strong financial support from the Ministry of Education Culture
Sports Science and Technology It was set up in 2012 as a five-year national project Although it is not a
consortium in a narrow sense its scope and research impact are substantial as more than 40 Japanese
leading scientific groups are part of this project It is led by Prof Haruo Inoue from the Tokyo Metropolitan
University further academic partners are amongst others the Tokyo University of Science the Tokyo
Institute of Technology Ibaraki University Ritsumeikan University and Hokkaido University
South Korea ndash KCAP
The Korean Centre for Artificial Photosynthesis (KCAP) was launched at Sogang University in 200924
set up
as a ten-year programme with 50 billion won (about euro40 million)25
It aims to secure a wide range of
fundamental knowledge necessary materials and device fabrication for the implementation of artificial
photosynthesis ie generating liquid fuel and oxygen from water and carbon dioxide using solar energy
through collaborative research with a number of research organisations and companies The Korean partners
comprise 14 professors from 8 universities including Sogang University Yonsei University and the Ulsan
National Institute of Science and Technology and one industry partner Pohang Steel Company26
Foreign academic partners are the Lawrence Berkeley National Laboratory California Institute of
Technology and University of California Berkeley The Centre has ties to other AP networks such as SOFI
and JCAP
US ndash JCAP
In 2010 the Department of Energy created the Energy Innovation Hubs and among them a Joint Centre for
Artificial Photosynthesis (JCAP) was established between the California Institute of Technology and the
Lawrence Berkeley National Laboratory in California27
JCAP draws on the expertise and capabilities of key
collaborators from the University of California (UCI and UCSD) and the SLAC National Accelerator Laboratory
operated by Stanford University The initial funds in 2010 amounted to $122 million JCAP is the largest
artificial photosynthesis network in the US with more than 190 persons linked to the programme The research
foci encompass electro-catalysis photo-catalysis and light capture materials integration and numerical
23
httpwwwmetigojpenglishpress20121128_02html 24
httpwwwk-caporkrenginfoindexhtmlsidx=1 25
httpwwwsogangackrnewsletternews2011_eng_1news12html 26
httpswwwicef-forumorgannual_2015speakersoctober8cs2appdfcs-2_20058_kyung_byung_yoonpdf 27
httpsolarfuelshuborgwho-we-areoverview
64
modelling test-bed prototyping and benchmarking The funds for the next five-year period (2016-2020)
amount to $75 million and are subject to congressional appropriation
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years Core members include the Northwestern University and
Uppsala University A process of exchanges is instituted which encompasses six different universities in four
countries Industry partners are ILampFS (India) Total (France) and Shell28
This list is not exhaustive and increasing interest in the field of artificial photosynthesis would certainly lead to
the launch of new national and international programmes
422 Main research groups (with link to network if any)
A list of the main research groups outside Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire AP
community outside of Europe We are confident however that it provides an accurate indication about the AP
sector outside of Europe
Table 43 Number of research groups and research institutions in non-European countries
Country Number of research groups Number of research institutions Average size of a
research group
Australia 1 1 18
Brazil 1 1 5
Canada 1 1 -
China 12 5 13
Israel 1 1 6
Japan 16 15 15
Korea 4 4 16
Singapore 1 1 14
US 40 32 18
Total 77 61 5
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 61 main research institutions or universities working on artificial photosynthesis outside of
Europe most of which are based in the US and in Japan Those research institutions contain 77 individual
research groups with an average group size of 8 people29
Yet the sizes of research groups can vary widely
from 26 members at the University of Tokyo to only two persons at Kobe University The country with both the
highest number of involved institutions and research groups is the US where 40 individual research groups in
32 research institutions are active Hence the US is a world leader in terms of research groups working on
AP Japan follows with 16 institutions and 15 research groups which lies below the numbers for Germany
and the Netherlands Almost 80 of the research groups (77) focus on the second pathway
(photoelectrocatalysis) whereas about 39 research the first pathway (synthetic biology amp hybrid
systems) The remaining 18 focus their activities on the third pathway (co-electrolysis) Table 44
28
httpwwwsolar-fuelsorgabout-sofi 29
The average group size is derived from survey responses For more information please refer to Annex I
65
provides an overview of some of the key statistics such as the number of AP research groups and institutions
per country and their respective focus on one of the three technology pathways
Table 44 Number of research groups per research area (technology pathway)
Country Technology
pathway
Total Synthetic biology
and hybrid systems
Photoelectrocatalysis Co-electrolysis
Australia 1 1 1 0
Brazil 1 0 1 0
Canada 1 0 1 1
China 12 4 6 2
Israel 1 1 0 1
Japan 16 7 15 1
Korea 4 0 4 0
Singapore 1 0 1 0
US 40 17 30 9
Total 77 30 59 14
Note a research group might focus on multiple technology pathways
Source Ecorys
In the following section our findings are illustrated by presenting some of the main research institutions and
their research groups
China ndash Dalian University of Technology
In 2011 the Dalian National Laboratory for Clean Energy (DNL) based at the Dalian Institute of Chemical Physics
(DICP) of the Chinese Academy of Sciences (CAS) was established It integrates research into clean energy and the
efficient use of fossil fuels to meet Chinas sustainable energy development strategy It is led by Li Can
Israel - Weizmann Institute of Science
To meet the challenge of providing clean sustainable energy the Weizmann Institute has established the Alternative
Sustainable Energy Initiative (AERI) The goal of this initiative is to create the conditions conducive to alternative
energy research and to identify promising avenues of research With the help of AERI the Weizmann institute hopes to
encourage its scientists to conduct basic research relevant to the future development of alternative sustainable energy
and to nourish the next generation of scientists in this field around the world in Israel and at the Weizmann Institute
The researchers at the Weizmann Institute of Science and at AERI preliminarily focus on the third pathway
Japan ndash University of Tokyo
The Domen Laboratory at the University of Tokyo is a research group focused on the second technological pathway
Their challenge is to find out novel photocatalysts that effectively work on water splitting under visible light by studying
different new materials
US ndash Arizona State University
The multidisciplinary team of the Center for Bio-inspired Solar Fuel Production of the Arizona State University aims to
design a complete system for solar water oxidation and hydrogen production Therefore they are focusing on five
specific subtasks (i) The total system analysis of the solar water-splitting device (ii) water oxidation (iii) fuel
production (iv) the artificial reaction center-antenna which relates to light collection and (v) the development of
functional nanostructured transparent electrode materials Their focus lies hence on the first and second AP technology
pathways
The density of research groups per country in the world is presented schematically in Figure 42 Please note
that in this figure (as opposed to Figure 41) we do not count each European country individually but
aggregate the numbers for all of Europe
66
Figure 42 Research groups active in the field of AP globally
Source Ecorys
43 Level of investment
In this section the level of investment is discussed in further detail The level of research investment in the EU
is based on the total budget of the projects whenever available In addition information is given on the time
period of the research projects
Information on the investment related to or funding of artificial photosynthesis research programmes and
projects at the national level is generally difficult to find especially for academic research groups Most budget
numbers found relate to the budget of the institution andor the (research) organisation in general and are not
linked to specific artificial photosynthesis programmes in particular unless the institute or research
programme is completely focused on artificial photosynthesis
Table 45 presents an overview of the investments made by a number of organisations
Table 45 Investments in the field of artificial photosynthesis
Country Organisation Budget size Period
Research investments in Europe
EU European Commission (FP7 and previous
funding programmes) euro 30 million 2005 - 2020
France CEA euro 43 billion 2014 covers not only AP
Germany
German Aerospace Centre (DLR) and the
Helmholtz Zentrum euro 4 billion
Annual budget covers
not only AP
Germany
Max Planck Institute for Chemical Energy
Conversion euro 17 billion 2015 covers not only AP
Germany
BMBF ldquoThe Next Generation of
Biotechnological Processesrdquo euro 42 million 2010 - present
Germany Government of Bavaria euro 50 million
2012-2016 covers not
only AP
Members of AMPEA AMPEA (EERA) euro 60 million 2010 - present
Netherlands Biosolar Cells euro 42 million 2010-present
Sweden Consortium for Artificial Photosynthesis euro 118 million 2013
UK SolarCAP and other initiatives in UK euro 92 million 2008-2013
67
Country Organisation Budget size Period
UK
University of East Anglia Cambridge and
Leeds euro 1 million 2013
Research investments outside Europe
China Dalian National Laboratory for Clean Energy euro 40 million Annual budget since
2011
Israel AERI euro 13 million 2014-2017
Japan ARPChem euro 122 million 2012 - 2021
Korea KCAP euro 385 million 2009 - 2019
UK US Plug-and-play photosynthesis euro 44 million 2014 - 2017
US JCAP euro 175 million 2010 - 2020
US SOFI euro 1 billion 2012 - 2022
Source Ecorys
431 Research investments in Europe
In Europe national researchers research groups and consortia are generally funded by European funds (such
as the ERC Grant from the European Commission) national governments businesses and universities In this
section special attention is paid to the EU FP7 projects These projects are mainly funded by European
contributions Further information is provided on AMPEA BioSolar Cells CAP SolarCap and some other AP
initiatives
Investments range between euro10 million for the national consortia (UK - SolarCap and Sweden - CAP) and euro42
million for the Dutch consortium to smaller budgets for local projects The projects at the European level are
more extensive The funds for all twenty FP7 projects related to artificial photosynthesis amount to a total
value of euro30 million AMPEA consists of around 400 professionals and an investment of approximately euro60
million contributed by the participants and associates themselves
Funding of AP research programmes and research consortia
EU ndash FP6 and FP7 projects
The FP6 and FP7 projects (6th
and 7th Framework Programmes for Research and Technological
Development) were undertaken in seven years between 2002 and 2013 and had a total budget of over euro60
billion30
Within FP7 around two thirds of the overall budget was aimed for the Cooperation programme of
which energy is one of the ten key thematic areas Investment in energy research under EU FP7 has been
around euro25 billion Various projects on artificial photosynthesis solar-powered hydrogen production by means
of water splitting have been completed under the EUrsquos Seventh Framework Programme Projects include
inter alia Solhydromics Solar-H Directfuel and H20Split FP7 is the key tool to respond to Europersquos needs in
terms of jobs and competitiveness and to maintain leadership in the global knowledge economy31
The
successor programme of FP7 has a number of projects in the field of artificial photosynthesis For example
PECDEMO project32
aims to develop a hybrid photoelectrochemical-photovoltaic tandem device with a solar-
to-hydrogen efficiency of 8-10 This illustrates the trend to move from fundamental research of materials and
processes (that was the main focus in FP6 and FP7 programmes) to the development of prototypes to reach
higher TRL levels (that is the main focus in H2020 programme)
An overview of the EU FP6 and FP7 projects on AP is presented in the table below
30
httpseceuropaeuresearchfp6pdffp6-in-brief_enpdf httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 31
httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 32
httppecdemoepflchpage-113311-enhtml
68
Table 46 EU FP6 and FP7 projects on artificial photosynthesis
EU FP7 project Technology pathway Total budget EU contribution to
the total budget
Time
period
(months)
ARTIPHYCTION Photolectrocatalysis (Water Splitting ) euro 3594581 euro 2187040 36
DIRECTFUEL Synthetic Biology amp Hybrid Systems euro 4977781 euro 3729519 48
CO2PHOTORED Photolectrocatalysis (Water Splitting ) euro 176053 euro 176053 24
COFLeaf Photolectrocatalysis (Water Splitting ) euro 1497125 euro 1497125 60
EWOCS Photolectrocatalysis (Water Splitting ) euro 168896 euro 168896 24
FAST MOLECULAR
WOCS
Photolectrocatalysis (Water Splitting )
euro 100000 euro 100000 48
H2OSPLIT Photolectrocatalysis (Water Splitting ) euro 100000 euro 100000 48
HJSC Research for fundamental understanding euro 337094 euro 337094 36
NANO-PHOTO-
CHROME
Synthetic Biology amp Hybrid Systems euro 218731
euro 218731 17
HyMap Photolectrocatalysis (Water Splitting ) euro 2506738 euro 2506738 60
PCAP Photolectrocatalysis (Water Splitting ) euro 190800 euro 190800 36
PHOTOCATH2ODE Photolectrocatalysis (Water Splitting ) euro 1500000 euro 1500000 60
PHOTOCO2 Photolectrocatalysis (Water Splitting ) euro 50000 euro 50000 24
PS3 Synthetic Biology amp Hybrid Systems euro 1997944 euro 1997944 60
SOLAR-H Synthetic Biology amp Hybrid Systems euro 2316000 euro 1800000 36
SOLAR-JET Photolectrocatalysis (Water Splitting ) euro 3123950 euro 2173548 48
SOLHYDROMICS Synthetic Biology amp Hybrid Systems euro 3655828 euro 2779679 42
SUSNANO Catalysts can be either used for hybrid
systems or the water splitting category euro 100000
euro 10000 54
TRIPLESOLAR Photolectrocatalysis (Water Splitting ) euro 2493585 euro 2493585 60
light2hydrogen Photolectrocatalysis (Water Splitting ) euro 900000
Total euro 30005106 euro 24016752 821
Source FP7 Project list
In total euro30 million of which 80 were based on European contributions have been spent on 20 projects
related to artificial photosynthesis Most projects were completely funded by the European Union On average
the time period of these projects was around 43 months the shortest project lasting only 17 months and the
longest one 60 months Almost all funding related to the topics of photoelectrocatalysis (55) and synthetic
biology amp hybrid systems (44) Some additional funding was spent on research for fundamental
understanding (the HJSC project) and catalysts which are useful for either hybrid systems or water splitting
(the SUSNANO project)
Table 47 Total EU budget on artificial photosynthesis per technology pathway
Technology pathway TRL Total budget
Synthetic biology amp hybrid systems 1-2 euro 13166284
Photoelectrocatalysis (water splitting ) 1-4 euro 16401728
Catalysts that can be used for both categories above 1-4 euro 100000
Research for fundamental understanding - euro 337094
Total - euro 30005106
69
Based on the monthly funding of the FP7 projects33
it may be observed that annual investments in artificial
photosynthesis have been increasing over the years (Figure 43) There were no projects on artificial
photosynthesis in 2008 therefore no investments were made The highest investment was made in 2014 with
euro45 million spent on projects After that investments have been decreasing It is however expected that
from 2016 more projects on artificial photosynthesis will be conducted therefore investment will rise
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020
Note It is assumed that the funding of the projects is evenly distributed over months Thus annual expenditures are
calculated as a sum of the monthly expenditures Project lsquolight2hydrogenrsquo is excluded from the calculation since there is no
information available on the number of months the project is running
Source Ecorys
EU ndash AMPEA (EERA)
EERA is an alliance of leading organisations in the field of energy research comprising more than 150
participating organisations all over Europe The primary focus of EERA is to accelerate the development of
energy technologies to the point that they can be embedded in industry-driven research Activities of EERA
are based on the alignment of own resources while over time the Joint Programmes can be expanded with
additional sources including from Community programmes34
In EERA approximately 3000 FTE (equivalent
of 3000 professionals) are involved which makes for a budget of around euro450 million35
AMPEA is one of the
programmes under EERA focusing on AP in which roughly 400 professionals are involved This would then
make for an investment of approximately euro60 million for AMPEA
The Netherlands ndash BioSolar Cells
The total budget of BioSolar Cells is around euro42 million based on public and private funds The Ministry
contributed euro25 million the NWO (The Dutch organisation on Scientific Research) euro35 million and Dutch
universities and research centres around euro7 million Private organisations invested euro65 million The specific
research programme Towards Biosolar Cells in which the Delft University of Technology is involved is
being allocated a budget of euro25 million by the Dutch Ministry of Agriculture Nature and Food Quality A
benefit of funding partly by private funding is the focus on building infrastructure and retaining key
33
It is assumed that funding is spread evenly over the months that the project is being implemented This means that if a project is running 36 months with a total budget of euro1 million it is assumed that monthly investments are euro83000 (1 million 12) If a project started in May 2010 then investment over the whole year 2010 is calculated as 8euro83000 After annual investment is calculated for all projects yearly total investment is calculated as a sum across projects
34 httpssetiseceuropaeuimplementationtechnology-roadmapeuropean-energy-research-alliance-eera
35 httpwwwapreitmedia168877busuoli_eneapdf
70
researchers Public funding of artificial photosynthesis is mostly for the short term facilitating the entry of new
groups36
Swedish ndash CAP
The Swedish Consortium for Artificial Photosynthesis connecting the universities of Lund Stockholm and
Uppsala is chaired by Stenbjoumlrn Styring There are 80 persons linked to the consortium In 2013 the Swedish
Energy Agency distributed the amount of euro118 million (SEK 108 million) in total to lsquosome of Swedenrsquos best
research groupsrsquo Out of this amount euro87 million went to three research groups at Uppsala University euro37
million to research on artificial photosynthesis to generate solar fuels euro32 million for research on dye-
sensitised solar cells and euro18 million to research on thin film solar cells (TFSC) It is the largest one-time
investment in solar energy ever in Sweden37
The Swedish Consortium for Artificial Photosynthesis ndash Stenbjoumlrn Styring
The project Molecular Solar Energy Sciences is funded by the KampA Wallenberg Foundation with euro5 million The main
research activities related to artificial photosynthesis include mechanistic studies on synthetic molecular and
moleculesemiconductor systems for the light-driven reduction of protons and CO2 and oxidation of water Furthermore
research is conducted on cyanobacteria systems for photo-biological fuel generation synthetic biology molecular
biology and metabolic engineering A second project on artificial photosynthesis is funded by the Swedish Energy
Agency (euro4 million) An additional four projects are funded by Swedish and European sources with a total of euro5
million38
UK ndash SolarCAP and others
The Engineering and Physical Sciences Research Council (EPSRC) in the UK supports several AP-related
projects through the Towards a Sustainable Energy Economy programme39
The total amount of funding is
approximately euro92 million
New and Renewable Solar Routes to Hydrogen is led by Imperial College London and is targeting both
artificial and natural photosynthetic routes to solar-derived hydrogen (euro5 million)40
Artificial Photosynthesis Solar Fuels is led by the University of Glasgow (euro2 million)41
The SolarCAP consortium for Artificial Photosynthesis is a consortium of five UK academic research
groups (based at the Universities of East Anglia Manchester Nottingham and York) they are working to
develop solar nanocells for the production of carbon-based solar fuels (euro22 million)
Funding of other AP initiativesprojects
Germany ndash German Aerospace Centre (DLR) and the Helmholtz Zentrum
The Helmholtz Zentrum is Germanyrsquos largest scientific organisation with more than 38000 employees and an
annual budget of more than euro4 billion42
It consists of 18 scientific technical biological and medical research
centres The research institutes of the German Aerospace Centre (DLR) are affiliated with the Helmholtz
Zentrum One of the Institutes of DLR the Institute of Solar Research forms part of the Helmholtz Zentrum
programme for renewable energies This programme focuses on projects on cost reduction in solar thermal
power plants the thermo-chemical generation of solar fuels in the period 2015-2019 the solar tower in Juumllich
the bioliq pilot plant and the Gross Schoumlnebeck geothermal research platform43
Research institutes submit
their research projects for evaluation by an international panel in order to qualify for funding under the
Renewable Energies Programme based on the outcome the Helmholtz Zentrum makes funding
recommendations for a five-year period
36
httpbiomassmagazinecomarticles2883towards-biosolar-cells-program-receives-government-funding 37
httpwwwuuseennewsnews-documentid=2282amptyp=artikelamparea=2amplang=en 38
Information is based on the survey responds 39
httpwwwrscorgglobalassets04-campaigning-outreachrealising-potential-of-scientistsresearch-policyglobal-challengessolar-fuels-2012pdf
40 httpgowepsrcacukNGBOViewGrantaspxGrantRef=EPF00270X1
41 httpgtrrcukacukprojectsref=EPF0478511
42 httpwwwdlrdesfendesktopdefaultaspxtabid-888515347_read-37692
43 httpwwwhelmholtzdeno_cacheenresearchenergyrenewable_energies
71
Germany ndash The Max Planck Institute for Chemical Energy Conversion (MPI CEC)
The MPI CEC was founded in 2012 to focus on the issue of energy conversion Its researchers analyse the
basic processes of energy storage and conversion within three research departments which encompass 200
employees44
The MPI CEC is for the most part financed by public funds from both the German state and
regions The MPI CEC is part of the Max Planck Society for the Advancement of Science which is a formally
independent non-governmental and non-profit association of German research institutes The budget of the
entire society amounted to euro17 billion in 2015
Germany ndash Federal Ministry of Education and Research (BMBF)
In 2010 the BMBF launched the initiative ldquoThe Next Generation of Biotechnological Processesrdquo45
Part of this
initiative were deliberations directed toward simulating biological processes for material and energy
transformation A funding amounting euro42 million is available for the first 35 projects on microbial fuel cells
artificial photosynthesis and universal production46
Germany ndash SolTech (Solar Technologies Go Hybrid)
The Government of Bavaria initiated SolTech an interdisciplinary project to explore innovative concepts for
converting solar energy into electricity and non-fossil fuels The project brings together research by chemists
and physicists at five different Bavarian Universities and is funded with euro50 million for the period 2012-201647
The SolTech network covers all fields of research on solar energy use such as the conversion of solar energy
to electricity for immediate use and the conversion of solar energy into chemical energy for storage and future
use
France - Alternative Energies and Atomic Energy Commission (CEA)48
CEA is a public government-funded research organisation active in four main areas low-carbon energies
defence and security information technologies and health technologies The CEA is the French Alternative
Energies and Atomic Energy Commission The CEA had a total budget of euro43 billion and around 16000
permanent staff On photovoltaic cell technology CEA is collaborating with Photowatt Pechiney and Appolon
Solar and on photovoltaic modules and systems with TOTAL Energie
UK - University of East Anglia (UEA) Cambridge and Leeds
A specific research programme by the UEA on the creation of hydrogen with energy derived from
photocatalysts designed to replicate photosynthesis is funded by the Biotechnology amp Biological Sciences
Research Council (BBSRC) The total amount of funding is approximately euro1 million (pound800000)49
432 Research investments outside Europe
The main research programmes and consortia discussed are JCAP (US) SOFI (US) ARPChem (Japan)
AnApple (Japan) and KCAP (Korea) In contrast to Europe the use of energy innovation hubs ie major
integrated research centres drawing together researchers from multiple institutions and varied technical
backgrounds is more common in the US and Asia Also partnerships between the government academia
and industry seem to be more common in those areas than they are in Europe The idea of developing new
energy technologies in innovation hubs is very different compared to the approach of helping companies scale
up manufacturing through grants or loan guarantees50
The information on the budgets from the large
networks is generally available
44
httpwwwcecmpgdeinstitutdaten-faktenhtml 45
httpswwwbiotechnologiedeBIONavigationENrootdid=164934htmlview=renderPrint 46
httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf 47
httpwwwsoltech-go-hybriddeabout-soltech 48
httpenglishceafrenglish-portal 49
httpwwwwiredcouknewsarchive2013-0122artificial-photosynthesis 50
httpswwwtechnologyreviewcoms429681artificial-photosynthesis-effort-takes-root
72
Funding of AP research programmes and research consortia
Japan ndash ARPChem
In Japan the Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology (MEXT) launched a large artificial photosynthesis project that will tackle the study for
the coming decade between 2012 and 2021 with an expected budget of about euro122 million (15 billion yen)
The main organisation to conduct the project is the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem)51
Japan ndash AnApple
All Nippon Artificial photosynthesis Project for Living Earth (AnApple) is a five-year research programme
(2012-2017) joined by more than 40 Japanese leading scientific groups In this strong collaboration they aim
at achieving breakthroughs for the realisation of artificial photosynthesis AnApple hosted The International
Conference on Artificial Photosynthesis (ICARP)rdquo in 2014 and receives strong financial support52
from the
Ministry of Education Culture Sports Science and Technology
Korea ndash KCAP
The Korea Center for Artificial Photosynthesis (KCAP) at Sogang University was established in September
2009 through complementary and collaborative research with the Lawrence Berkeley National Lab (LBNL) in
the US to build the foundation for the realisation and commercialisation of artificial photosynthesis KCAP
receives a grant of euro385 million (50 billion won in 10 years) from the Ministry of Education Science and
Technology (MEST) through the National Research Foundation of Korea (NRF)
US - JCAP
JCAP (Joint Centre for Artificial Photosynthesis) was established in 2010 by the Department of Energy as one
of the Energy Innovation Hubs with a fund of euro108 million ($122 million) for five years Additional funding for
the next five years amounts to euro67 million ($75M) but is still subject to congressional appropriation53
JCAP
is the largest artificial photosynthesis research programme in the world There are 190 persons linked to the
research programme
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years SOFI (Solar Fuels Institute) is focused on light capture
water splitting CO2 catalysis and photoelectrochemical cells SOFI relies on a community of member
institutions and individual supporters who believe strongly in a clean energy future54
The solar fuel created
using catalysts and technology shared by global members of SOFI is funded by crowdfunding campaigns
(Kickstarter campaign) Furthermore SOFI partnered with TSRC to raise by means of a bold campaign one
billion dollars over the next ten years to fund the research55
Funding of other AP initiativesprojects
US ndash Plug-and-play photosynthesis CAPP (combining algal and plant photosynthesis)
Three UKUS-funded projects received funding to improve photosynthesis The three research teams (each
comprised of scientists from the United Kingdom and the United States) have been awarded a second round
of funding to build on their research findings and develop new ways to improve photosynthesis Projects
include plug-and-play photosynthesis by the Arizona State University Multi-level Approaches for Generating
Carbon Dioxide (MAGIC) led by the Pennsylvania State University and Combining Algal and Plant
Photosynthesis (CAPP) led by the Stanford University received in 2014 a new round of funding of euro44 million
51
httpwwwmetigojpenglishpress20121128_02html 52
httpartificial-photosynthesisnetICARP2014scopehtml The concrete funding figures are not available 53
httpenergygovarticlesenergy-department-provide-75-million-fuels-sunlight-hub) httpsolarfuelshuborgresearchoverview 54
httpwwwsolar-fuelsorgdonate 55
httpstelluridescienceorgsofi-brochurepdf
73
(pound5 million) in total over three years from the Biotechnology and Biological Sciences Research Council
(BBSRC) and the National Science Foundation56
Israel ndash Projects funded by AERI
AERI is providing a pool of funds to try out new ideas and jump-start research projects that are not applicable
for conventional grants Since 2006 already 8 cycles of AERI-funded projects took place Projects under the
20132014 cycle include lsquoNew Options for Solar Energy Conversion to Biofuel and Electricity ndash Biofuels ndash
Photovoltaics and Opticsrsquo57
Funding is provided by the Canadian Center for Alternative Energy Research the
Helmsley Energy Program the Helmsley Charitable Trust (providing euro13 million ($15 million) over three
years) the Burk Fund for Alterative Energy Studies the Eisenberg Foundation and individuals58
China ndash Funding of the Dalian National Laboratory for Clean Energy
The Dalian National Laboratory for Clean Energy was established in 2011 The investments into this lab
amount to more than euro40 million (289 million RMB) a year (over 50 of annual research of the Dalian
University of Technology within which the laboratory functions)59
In addition to this laboratory Haldor Topsoe
opened an RampD Center60
at the same university to join forces in the research of clean energy Haldor Topsoe
is also going to sponsor RampD projects however the size of the investments is not revealed Prior to that
Topsoe already established a scholarship with a value of around euro400 a month (3000 RMB)61
44 Strengths and weaknesses
This section presents the analysis of the strengths and weaknesses of the research community in the field of
artificial photosynthesis The findings are based on the results of the survey conducted during March 2016
and are supplemented by desk research Firstly we outline the main strengths and weaknesses with regard to
global AP research Secondly the strengths and weaknesses of the European community compared to the
non-European community are presented
441 Strengths and weaknesses of AP research in general
Table 48 below summarises the strengths and weaknesses of research in AP taking a global perspective
Table 48 Summary of strengths and weaknesses of research globally
Strengths Weaknesses
A diverse community of researchers bringing together
experts in chemistry photochemistry electrochemistry
physics biology catalysis etc
Researchers focus on all technology pathways in AP
Existing research programmes and roadmaps in AP
Available financial investments in several countries
Limited communication cooperation and collaboration
at an international level
Limited collaboration between academia and industry
at an international level
Transfer from research to practical applications is
challenging
Note International level refers not only to EU countries but all around the world
Globally there is a wide variety of RampD institutes (and researchers) focused on AP forming a diverse
community of researchers Research in AP requires interdisciplinary teams The experts working together
on this topic often have backgrounds in chemistry physics and biology
56
httpwwwbbsrcacuknewsfood-security2014140602-pr-bbsrc-and-nsf-funding-photosynthesis 57
httpwwwweizmannacilAERIresearch 58
httpwwwweizmannacilresdevsitesweizmannacilresdevfilesenergy_booklet_lo_res_2012pdf 59
httpwwwnaturecomnews2011111031fullnews2011622html 60
httpwwwtopsoecomnews201602topsoe-establishes-rd-center-dalian-institute-chemical-physics-china 61
httpwwwdnlorgcnshow_enphpid=776
74
A diverse community of researchers is focusing on all the pathways in AP which ensures diverse
approaches an exchange of different views a dynamic research community and avoids lock-ins into one
specific pathway This broad and inclusive research approach is the best way to maximise the probability of
AP research being successful in developing efficient and commercially viable AP processes
Several countries have dedicated programmes andor roadmaps to the topic of AP The US Japan the
Netherlands and South Korea have invested in large-scale interdisciplinary research programmes (specifically
on solar fuels) China and Japan have dedicated centres for renewable energy research where solar fuels are
an area of substantial effort For example the Department of Energy of the US sponsors Energy Innovation
Hubs aiming to overcome scientific barriers to develop a complete energy system with the potential to turn into
a transformative energy technology62
One of such innovation hubs is the Joint Center for Artificial
Photosynthesis established in 2010 In the Netherlands a public private partnership was established to form
BioSolar Cells of which one of the main focal themes is AP Globally several hundreds of millions of euros
are being spent this decade on AP research and this research seems to be intensified further
Despite the intensification of global research efforts the communication cooperation and collaboration at
an international level remains limited Many AP consortia link different research groups but operate only at
a national level63
Yet a higher level of institutionalised international or global cooperation going beyond
international academic conferences could spur innovative research in the field and enhance knowledge
exchange and spill-overs A number of survey respondents indicated that the lack of coordination
communication and cooperation at an international level is one of the main weaknesses in current AP-related
research activities
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research
including research on artificial photosynthesis In Japan the industry is involved in AP research to a greater
degree64
Nevertheless although companies are participating in local consortia such as ARPChem and
BioSolar Cells there seems to be a lack of cooperation between academia and industry at an
international level
The transfer of research to industrial application in artificial photosynthesis remains challenging In order
to attract the attention of the private sector artificial photosynthetic systems must be cost-effective efficient
and durable An active involvement of industrial parties could help bringing research prototypes to
commercialisation This step towards commercialisation requires a sufficient critical mass and funding
however which cannot be borne by a single country
442 Strengths and weaknesses of AP research in Europe
Table 49 below summarises the strengths and weaknesses of research in artificial photosynthesis in Europe
as compared to non-European research
62
httpscienceenergygovbesresearchdoe-energy-innovation-hubs 63
The only exception is AMPEA with its pan-European reach 64
The Korean Centre for Artificial Photosynthesis (KCAP) collaborates with a number of companies Toshiba and Panasonic made some advances in artificial photosynthesis research (httpasianikkeicomTech-ScienceScienceHow-artificial-photosynthesis-could-cut-emissions) ARPChem has a few corporate members on board (httpwwwmetigojpenglishpress2012pdf1128_02bpdf)
75
Table 49 Summary of strengths and weaknesses of research in Europe
Strengths Weaknesses
A strong diverse community of researchers
RampD institutions research capacity and facilities
Existing research programmes and roadmaps for AP in
several MS
Available financial investments in MS
Ongoing and conducted FP7 projects at EU level
Close collaboration of research groups in consortia
Limited communication cooperation and collaboration at
a pan-European level
Limited collaboration between academia and industry
within Europe
Limited funding mostly provided for short-term projects
focusing on short-run returns
National RampD efforts in AP are scattered
Europe has a diverse research community working on artificial photosynthesis research covering all the
technology pathways Europersquos universities have many highly educated researchers in the fields of chemistry
physics and biology at their disposal There is a solid foundation of RampD institutions research capacity
and facilities such as specialised laboratories which work together at a national level
National research programmes and roadmaps for AP exist in several Member States an indication that
AP research is on the agenda of European governments65
Therefore also financial investment for AP
research is available in several MS such as in Germany66
and other countries European-level
collaboration between different research groups and institutes from different countries has been achieved in
the framework of FP7 projects67
as well as predecessors of it
Five main consortia in Europe ensure that research groups and research institutes are collaborating
closely68
such as in Sweden where the Consortium for Artificial Photosynthesis (CAP) is active and in the
Netherlands where researchers work in close cooperation within the BioSolar Cells consortium Nevertheless
there is still much room to expand globally as well as within Europe most consortia are operating within and
collaborating with research groups in countries where they are based themselves
The level of cooperation and collaboration at a pan-European level hence seems to be limited There
are a few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7 projects
but many research groups are operating locally and are funded by national governments Several survey
respondents reported a low degree of collaboration among different research groups which typically results in
a duplication of efforts and a lack of generalised standards Synergies which could potentially boost research
in artificial photosynthesis are being overlooked Creating for example a communication platform to facilitate
the exchange among researchers could more easily promote the development of knowledge and increase the
speed of discovery and exploitation of new robust (effective and durable) photocatalysts innovative processes
and devices etc Moreover another indicated weakness is the lack of collaboration between already existing
and ongoing projects
While industrial companies are present in a few consortia there is limited collaboration between European
academia and industry Improved collaboration could result in the development of more advanced AP
processes and AP process devices and it might improve the probability of APrsquos successful commercialisation
in the foreseeable future
65
For example Strategic Energy Technology (SET) Plan European Biofuels Technology Platform (EBTP) and European Industrial Bioenergy Initiative (EIBI) JCAP scientific programme For more information please refer to Deliverable 1 Chapter 32
66 By now research funded by the government of Germany in the field of artificial photosynthesis amounts to euro 42 million (httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf)
67 See Deliverable 1
68 httpswwwleopoldinaorgenpolicy-adviceworking-groupsartificial-photosynthesis
76
The long-term focus of AP research is a hurdle for both gaining cooperation with industry and for obtaining
funding Compared to that of its non-European counterparts European funding focuses on the short
term69
While in the USA and Japan funding is dedicated for about 5-10 years European parties often get
funding for about 4 years at the most Although several MS also have dedicated RampD programmes focusing
on AP the amounts provided by non-European counterparts exceed those of the European70
Furthermore
these national programmes are fragmented ie lacking a common goal and perspective hence the funding
of research is also fragmented and scattered71
The European community of researchers could benefit
from an integrated programme which clearly indicates research goals and objectives In addition a common
funding scheme set up to support fundamental research in artificial photosynthesis and to promote
collaboration with industry could advance the research in artificial photosynthesis
A number of survey respondents indicated that there is currently little focus of EU-funded research on
technologies with low TRL within H2020 At the moment there is a strong emphasis on the projects and
technologies which already have a rather high TRL expecting returns in the near future while research in the
area of low TRL technologies requires some attention and funding Several respondents mentioned that there
exist still quite some barriers regarding the design of low-cost materials with low TRL and with higher stability
and activity (eg performance of devices when it comes to a discontinuous supply of energy)72
45 Main industrial actors active in AP field
451 Industrial context
The idea behind artificial photosynthesis is that solar fuels could solve worldwide energy problems by using
water and carbon dioxide and converting them into the fuels we need Artificial photosynthesis can convert
sunlight directly into chemical fuels which makes it possible to harvest and store energy However there are
still many obstacles to make this technology commercially viable Only if artificial photosynthesis can be
provided efficiently stably safely and cheaply will it be beneficial for the public This means inter alia that an
efficient light absorber and catalysts need to be created to convert sunlight into fuel Even though there are
rapid developments in the field of artificial photosynthesis there are many obstacles to overcome in order to
reach mass production Currently the positioning of the fields of artificial photosynthesis and solar fuels is at
around a 3 on the technology readiness level
452 Main industrial companies involved in AP
At the moment the number of companies active in the field of AP is limited Based on our analysis of the main
AP actors in the industry only several tens of companies appear to be active in this field Moreover industrial
activity is limited to research and prototyping as viable AP technologies have not (yet) been commercialised
35 companies active in the field of AP have been identified comprising 16 European companies and 19 non-
European companies (Table 410) Seven of these are in Germany eight in the Netherlands eight in Japan
and 10 in the US The following table summarises the countries in relation to one or more of the technology
pathways
69
Already in 2013 it was indicated that much of public funding of basic AP research remains short term For more information see Thomas FaunceStenbjorn Styring Michael R Wasielewski Gary W Brudvig A William Rutherford et al (2013) Artificial Photosynthesis as a Frontier Technology for Energy Sustainability Energy amp Environmental Science Issue 4 2013
70 A number of respondents indicated that the available funding is not sufficient to finance research facilities and equipment
71 This weakness is indicated by several respondents
72 This is also mentioned as one of the areas of attention in Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press)
77
Table 410 Overview of the size of the industrial community number of companies per pathway
Country Synthetic biology amp
hybrid systems
Photoelectrocatalysis Co- electrolysis Total number of
companies
European companies
France 1 1 0 1
Germany 2 2 0 4
Italy 0 1 0 1
Netherlands 3 4 1 8
Switzerland 0 1 0 1
Total 6 9 1 15
Non-European companies
Japan 0 8 0 8
Saudi Arabia 0 1 0 1
Singapore 0 0 1 1
US 3 2 4 8
Total 3 11 5 19
Note a company can be active in multiple technology pathways
Source Ecorys
With respect to the industry largely the same countries stand out as in the research field namely Japan the
US and north-western Europe The industry in Japan appears to have the most intensive research activities
in AP as several large Japanese multinationals have set up their own AP RampD laboratoriesresearch
departments
With respect to the three technology pathways (i) synthetic biology amp hybrid systems (ii) photoelectrocatalysis
and (iii) co-electrolysis we have observed that most industrial (research) activity is being performed
concerning photoelectrocatalysis (19 companies) although there are also companies active in the two other
pathways
We have also identified a number of companies active in the area of carbon capture and utilisation that might
potentially be involved in the research of artificial photosynthesis
453 Companies active in synthetic biology amp hybrid systems
The pathway involving synthetic biology amp hybrid systems is still at an early stage on the TRL scale (TRL 1-2)
The challenges industries face relate mostly to efficiency obstacles Enzymes and proteins need to be
modified by genetic engineering Another barrier relates to the fact that the modifications and protein
production are still very time-consuming in terms of cell growthprotein purification Furthermore it is
necessary to improve protein stability and solubility by rational design directed evolution and modifying
sample conditions since currently proteins are unstable It would probably take about 10-20 years until
technologies reach TRL 7
The companies involved in this pathway range from chemical and oil-refining companies companies working
on bacteria companies producing organic innovative catalysts to others The following table lists the
organisations identified within this pathway
78
Table 411 Organisations in synthetic biology amp hybrid systems
Country Organisation (in EN)
France PhotoFuel
Germany Evonik Industries AG
Germany Brain AG
Italy Hysytech
Netherlands Biomethanol Chemie Nederland BV
Netherlands Photanol BV
Netherlands Tendris Solutions
Netherlands Everest Coatings
US Joule Unlimited
US Phytonix
US Algenol
Source Ecorys
Chemical and oil-refining companies
Biomethanol Chemie Nederland BV a Dutch company that produces and sells industrial quantities of high
quality bio-methanol focusing on synthetic biology amp hybrid systems is also a partner of the BioSolar Cells
programme The BioSolar Cells programme focuses its research on artificial photosynthesis photosynthesis in
cellular systems and photosynthesis in plants
Companies working on bacteria
Another group of companies in the pathway of synthetic biology amp hybrid systems focus on CO2 to fuel
processes that use cyanobacteria to convert CO2 into targeted fuels or chemicals (biological conversion)
Examples of such companies are Joule Unlimited Phytonix and Algenol all based in the US Algenol is
commercialising its patented algae technology platform for the production of ethanol using proprietary algae
sunlight carbon dioxide and saltwater The Dutch company Photanol uses cyanobacteria to turn CO2 into
certain predetermined products
Companies producing organic innovative catalysts
Many of the smaller companies currently active in developing AP originate from a specific research group or
research institute and focus on specific AP process steps andor process components Some companies
focus on the further development of both chemical and organic innovative catalysts which are earth-abundant
non-toxic and inexpensive Brain AG (Germany) is an example of such a company
Other companies
Hysytech is an Italian company experienced in technology development and process engineering applied to
the design and construction of plants and equipment for fuel chemical processing energy generation and
photoelectrocatalysis Hysytech is involved in an FP7 project to develop a fully artificial photoelectrochemical
device for low temperature hydrogen production
Other companies in the field of synthetic biology amp hybrid systems are Tendris Solutions (Netherlands) and
Everest Coatings (Netherlands) involved in the EET-Kiem project which focused on increasing the
absorption of visible light in the TiO2 photocatalyst by incorporating other elements in the structure and to
construct a photoelectrochemical reactor Photofuel in France and Phytonic in the US focus on synthetic
biology amp hybrid systems and photoelectrocatalysis Evonik Industries AG invests in synthetic biology amp
hybrid systems as well as carbon capture technologies which convert waste CO2 into products and fuels
79
454 Companies active in photoelectrocatalysis
The pathway of photoelectrocatalysis is relatively low on the TRL scale as well (TRL 1-4)
Photoelectrocatalysis would make it possible to use photovoltaic cells that absorb photons to facilitate water
splitting Research on photoelectrocatalysis using photoelectrochemical cells in particular is still at a very early
stage
Technologies pertaining to the photoelectrocatalysis pathway are not yet commercially viable with the main
challenges relating to the design of devices that are efficient stable and durable Further potential obstacles to
be taken into account relate to the incorporation of these technologies with other technologies that can
generate fuel molecules other than hydrogen
Most companies are involved in this pathway ranging from automotive manufacturers and electronic
companies to chemical and oil-refining companies The following table lists the organisations identified within
this pathway
Table 412 Organisations in the field of photoelectrocatalysis
Country Organisation (in EN)
France PhotoFuel
Germany Bauhaus Luftfahrt eV (Bauhaus Luftfahrt Research)
Germany ETOGAS
Italy Hysytech
Japan Toyota (Toyota Central RampD Labs)
Japan Honda (Honda Research Institute - Fundamental Technology Research Center)
Japan Mitsui Chemicals
Japan Mitsubishi (Mitsubishi chemicals Setoyama Laboratory)
Japan Sumitomo Chemicals (Energy amp Functional Materials Research Laboratory)
Japan INPEX Corporation
Japan Toshiba (Corporate Research and Development Center)
Japan Panasonic (Corporate Research and Development Center)
Netherlands InCatT BV
Netherlands Shell (Shell Game Changer Programme)
Netherlands Hydron
Netherlands LioniX BV
Saudi Arabia Saudi Basic Industries Corporation
Switzerland SOLARONIX SA
US HyperSolar
Source Ecorys
Companies in the automotive sector
Several automotive manufacturers are active in the field of AP mostly relating to the field of
photoelectrocatalysis In 2012 Honda opened a hydrogen station in Saitama Japan that converts sunlight
into hydrogen that could be used to power fuel-cell electric vehicles The station is focusing on
photoelectrocatalysis and turning sunlight into hydrogen via a high-pressure water electrolysis system that
was developed by Honda itself Since then there seems to be little activity from Honda73
73
httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
80
Figure 44 Hondarsquos sunlight-to-hydrogen station
Source httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
Toyota succeeded (in 2011) to generate organic compounds via artificial photosynthesis without using any
external energy andor material sources The system is focused on producing formic acid (which could be
used as a raw material in industry) In February 2016 Toyota Central RampD Labs announced that they
achieved the worldrsquos highest energy conversion efficiency rate of 46 with artificial photosynthesis using
water and carbon dioxide as raw materials and sunlight as energy to produce useful materials Toyota is also
researching new chemical reactions to generate more valuable organic compounds as a final product such as
methanol Toyota is primarily focused on photoelectrocatalysis The companyrsquos 2020 goal is to complete basic
testing for the creation of primary CO2-absorbing materials (material or fuel)74
Electronic companies
In addition to car manufacturers also electronic companies are involved in photoelectrocatalysis In December
2014 Toshiba announced its focus on producing a catalyst made of gold The company indicated that they
found a way to modify gold at the atomic level using nanotechnology which allows carbon dioxide to change
into other compounds at a lower voltage (with a record of 15 energy efficiency rate)75
In September 2015 Toshiba made public that the company developed a prototype of a new highly efficient
molecular catalyst (consisting of an imidazolium salt) that converts carbon dioxide into ethylene glycol without
producing other and unwanted by-products Most artificial photosynthesis technologies use a two-electron
reduction conversion process producing carbon monoxide and formic acid Others can achieve direct multi-
electron reduction but tend to produce many by-products and their separation can be problematic Toshibas
new molecular catalyst converts carbon dioxide into ethylene glycol via multi-electron reduction The long-term
goal of Toshibarsquos research work is to develop a technology compatible with carbon dioxide capture systems
installed at facilities such as thermal power stations and factories utilising carbon dioxide to provide (storable)
energy To this end Toshiba focuses on photoelectrocatalysis and further improvement of the conversion
efficiency by increasing catalytic activity and aims at practical implementation in the 2020s76
Panasonics artificial photosynthesis system is also focused on photoelectrocatalysis in particular on highly
efficient CO2 conversion which can utilise direct sunlight or focused light In 2012 Panasonic found that a
nitride semiconductor has the capability to excite the electrons with enough high energy for the CO2 reduction
reaction to take place Nitride semiconductors have attracted attention for their potential applications in highly
74
httpwwwtytlabscom and httpswwwasiabiomassjpenglishtopics1603_01html 75
httpwwwjapantimescojpnews20150412nationalscience-healthlab-photosynthesis-begins-to-bloomVw1YZP5f3IV 76
httpswwwtoshibacojprdcrddetail_ee1509_01html
81
efficient optical and power devices for energy saving However its potential was revealed to extend beyond
solid devices more specifically it can be used as a photoelectrode for CO2 reduction By making a devised
structure through the thin film process for semiconductors the performance as a photoelectrode has greatly
improved77
In September 2014 Panasonic Corporation managed to achieve a conversion efficiency rate of
0378
and not long after that the company announced to having achieved the first formic acid generation
efficiency of approximately 10 as of November 201479
According to Panasonic the key to achieving an
efficient artificial photosynthetic system lies in improved photoelectrodes and oxidation-reduction electrodes
Chemical and oil-refining companies
The developments with respect to solar fuels are also being supported by several chemical and oil-refining
companies Artificial photosynthesis has been an academic field for many years However in the beginning of
2009 Mitsubishi Chemical Holdings reported to be undergoing its own artificial photosynthesis research by
using sunlight water and carbon dioxide to create the carbon building blocks from which resins plastics and
fibres can be synthesisedrdquo80
In 2014 Mitsubishi established the research organisation Setoyama Laboratory
The Laboratory focuses on the development of artificial photosynthesis for chemical processes which is the
synthesis of raw materials such as ethylene propylene butenes etc by means of solar hydrogen obtained by
catalytic water splitting under visible light and CO2 emitted at a plant site81
The laboratory is also participating
in the ldquoArtificial Photosynthetic Chemical Processrdquo project (denoted ldquoARPChemrdquo) granted by NEDO (New
Energy Development Organization) In this project the following three programmes are conducted through
collaboration with academia and industry
1 Design of a photo semiconductor catalyst for water splitting
2 A membrane separation system for H2 from gas mixtures composed of H2 and O2 and
3 A catalytic process for the synthesis of lower olefins from H2 and CO2
The Japanese chemical companies Sumitomo chemicals and Mitsui Chemicals focusing on carbon
capture and photoelectrocatalysis are also participating in the ARPChem programme Sumitomo has its
own Energy amp Functional Materials Research Laboratory and is conducting research and development in a
broad range of fields Mitsui created the Mitsui Chemicals Catalysis Science Award and the Mitsui Chemicals
Catalysis Science Award of Encouragement in order to award recognition to national and international
researchers that have made substantial contributions to the field of catalysis science In 2014 it was the fifth
time that Mitsui has given these awards
Royal Dutch Shell cooperated with Bauhaus Luftfahrt in the EU-funded Solar-Jet project (2011-2015) in the
area of photoelectrocatalysis aimed at demonstrating an innovative process technology using concentrated
sunlight to convert carbon dioxide and water into synthesis gas (syngas) The syngas a mixture of hydrogen
and carbon monoxide is ultimately converted into kerosene by means of the commercial Fischer-Tropsch
technology With the first ever production of synthesised ldquosolarrdquo jet fuel the SOLAR-JET project has
successfully demonstrated the entire production chain for renewable kerosene obtained directly from sunlight
water and carbon dioxide (CO2)82
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University (US)
SOFI leads a global consortium that brings together universities from Rutgers University in New Jersey to
Uppsala University in Sweden83
SOFI focuses on both the water-splitting process (production of hydrogen)
and the CO2 reduction process (the reduction of carbon dioxide to carbon monoxide which in combination
77
httpnewspanasoniccomglobalpressdata201207en120730-5en120730-5html 78
httpswwwasiabiomassjpenglishtopics1603_01html 79
httpwwwpanasoniccomglobalcorporatetechnology-designtechnologyphotosynthesishtml 80
httpwwwdigitalworldtokyocomindexphpdigital_tokyoarticlesmanmade_photosynthesis_looking_to_change_the_world 81
httpwwwmcrccojpenglishrdsetoyama_laboratoryhtml 82
httpwwwsolar-jetaeropagepostsartsunlight-to-jet-fuel-european-collaboration-solar-jet-for-the-first-time-demonstrates-the-entire-production-path-of-ldquosolarrdquo-kerosene-4php
83 httpappsnorthbynorthwesterncommagazine2015springsofi
82
with hydrogen can be processed into eg methanol or synthetic gasoline) Total is also a partner of the
BioSolar Cells programme
INPEX Corporation is a Japanese oil company established in February 1966 as North Sumatra Offshore
Petroleum Exploration Co In addition to Mitsubishi Chemicals Sumitomo Chemicals and Mitsui Chemicals
INPEX also participates in the ldquoJapan Technological Research Association of Artificial Photosynthetic
Chemical Processrdquo (ARPChem) programme and engages in RampD projects with the aim to produce chemical
products like plastics and hydrocarbon fuel from photochemical catalysis INPEX Corporation is focused on
photoelectrocatalysis
Other companies
Other companies include Etogas (Germany) which develops builds and selects Power-to-Gas plants and
products related to Power-to-Hydrogen Power-to-SNG and Hydrogen-to-SNG LnCatT BV (Netherlands)
Hydron (Netherlands) Saudi Basic Industries Corporation (Saudi Arabia) and Hyper Solar () all focus on
photoelectrocatalysis LioniX BV (Netherlands - photoelectrocatalysis) and Solaronix SA (Switzerland -
photoelectrocatalysis) are focused on the further development of photoelectrochemical cells Hysytech and
Photofuel are in addition to the first pathway also involved in the second
455 Companies active in co-electrolysis
Even though co-electrolysis is the pathway at the highest levels of technical readiness compared to the other
two pathways not many companies are involved in it There are three electrolyser types capable of producing
hydrogen gas eg alkaline electrolysis polymer electrolyte membrane electrolysis and solid oxide electrolysis
cells (SOECs) Multiple designs are commercialised although SOECs using Fischer-Tropsch synthesis are
not yet commercially viable The companies involved in this pathway are mainly from the US Industries
combine co-electrolysis and the field of carbon capture Fuel cell products are used in the automotive
telecom defenceaerospace and consumer product sectors
The following table summarises the organisations in the field of co-electrolysis
Table 413 Companies in co-electrolysis
Country Organisation (in EN)
Netherlands Shell (Shell Game Changer Programme)
Singapore Horizon Fuel Cell Technologies
US Catalytic Innovations
US Opus 12
US LanzaTech
US Proton onsite
Source Ecorys
Companies include Proton onsite (US ndash PEM electrolysis) which manufactures hydrogen nitrogen and zero
air generators in a safe reliable and cost-effective way Horizon Fuel Cell Technologies (Singapore)
focuses on commercially viable fuel cells starting by simple products which need smaller amounts of
hydrogen The technology platform of horizon fuel cell technology is focused on three main topics PEM fuel
cell systems hydrogen supply and hydrogen storage Catalytic Innovations (US) Opus 12 (US) Lanzatech
(US) and Shell (NL) are also involved in the second pathway
83
456 Companies active in carbon capture and utilisation
The technology in the carbon capture and storage pathway can capture up to 90 of the CO2 and allows for
the separation of carbon dioxide from gases produced in electricity generation and industrial processes by
means of combustion capture and oxyfuel combustion The most advanced technologies are at TRL 7 eg
carbon capture in a coal plant
The following table shows the organisations active in the field of carbon capture and utilisationre-use
Table 414 Organisations active in carbon capture and utilisation
Country Organisation (in EN)
Denmark Haldor Topsoe
Germany Evonik Industries AG
Germany Siemens (Siemens Corporate Technology CT)
Germany Sunfire GmbH
Germany Audi
Switzerland Climeworks
UK Econic (Econic Technologies)
Canada Carbon Engineering
Canada Quantiam
Canada Mantra Energy
Iceland Carbon Recycling International
Israel NewCO2Fuels
Japan Mitsui Chemicals
US Liquid light
US Catalytic Innovations
US Opus 12
US LanzaTech
US Global Thermostat
Source Ecorys
Twelve companies currently only focus on carbon capture and utilisation These companies are therefore
technically not considered to be companies involved in artificial photosynthesis However they can potentially
be involved in AP research in the future Such companies include automotive manufacturers as well as
electronics companies Five companies are involved in carbon capture and one of the pathways
Automotive manufacturers
Audi is working together with the American company Joule Unlimited in order to research and produce lsquoe-
ethanolrsquo Joule optimised a production process in which microorganisms are able to produce and excrete
either ethanol or alkanes from carbon dioxide (CO2) and sunlight Audi and Joule opened a joint
demonstration plant in September 2012 where e-ethanol is produced in transparent plastic tubes (see Figure
45)
84
Figure 45 Demonstration facility of Audi and Joule in Hobbs (New Mexico)
Source httpwwwbest-practicesfrost-multimedia-wirecomjoule2015
In January 2014 Audi e-ethanol underwent its first-ever test cycle in the pressure chamber and glass engine
showing that fewer pollutants are produced in the combustion of e-ethanol than is the case with bio-ethanol84
Since 2011 Audi has also been collaborating with Joule to produce e-diesel Finally in November 2014 Audi
opened a research facility in Dresden with project partners Climeworks and the start-up Sunfire in order to
produce its first batches of synthetic diesel combining two innovative technologies CO2 capture from the
ambient air (Climeworks) and the power-to-liquid process for the production of synthetic fuel (Sunfire)85
Currently Audi is investing in carbon capture and utilisation technologies
Electronics companies
Electronics companies such as Siemens are also investing in carbon capture technologies Developers at
Siemens Corporate Technology (CT) in Munich are currently active in the project CO2-to-value The challenge
of the project is to charge only carbon dioxide with electrons and not the surrounding water molecules
because the latter would merely result in the production of conventional hydrogen Specialists at the University
of Lausanne in Switzerland and materials scientists at the University of Bayreuth are working with Siemens to
develop catalysts on their behalf Siemens takes on a pragmatic approach by focusing on only one step in the
AP process They are not yet trying to capture light Instead they are centring their research activities on
activating CO2 and converting it into products such as (i) ethylene which the chemical industry needs for the
production of plastics (ii) methane the main component of natural gas and (iii) carbon monoxide which can
be used to produce fuels such as ethanol86
Other companies
Figure 46 illustrates the process of NewCO2Fuels (NCF) an Israeli company focused on carbon capture
This is a high-temperature-driven CO2- and water-dissociation process that produces syngas (a mixture of
CO and H2) from which various synthetic fuels and chemicals can be produced
In the short term NCF is focusing on the design and building of a first pilot plant as well as raising the
necessary funds for it
In the mid term NCF plans to offer its technology to the energy intensive industries such as the steel
gasification and glass industries to transform their CO2 waste streams into feedstock
In the long term NCFrsquos vision is to use solar energy to convert CO2 captured immediately from the
atmosphere into valuable products
84
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 85
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 86
httpwwwsiemenscominnovationenhomepictures-of-the-futureresearch-and-managementmaterials-science-and-processing-co2tovaluehtml
85
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels
Source httpwwwnewco2fuelscoilproduct8overview
Furthermore some companies focus on chemical or biological CO2-to-fuel production Examples of
companies that focus on direct (co-electrolysis) CO2 to fuels production are Carbon Recycling (Iceland) and
Econic (UK ndash carbon capture) The company Liquid Light (US ndash carbon capture) focuses on the
electrochemical conversion of CO2 to chemicals
Other companies involved in carbon capture are Global Thermostat (US) Quantiam (Canada) Carbon
Engineering (Canada) Evonik Industries AG (Germany) and Haldor Topsoe (Denmark) Besides co-
electrolysis Catalytic Innovations Opus 12 and Lanzatech are also involved in carbon capture Mitsui
Chemical is focusing on carbon capture as well as photoelectrocatalysis
457 Assessment of the capabilities of the industry to develop AP technologies
Although there is a lot of research activity going on in the field of AP both at the academic and industrial level
the technology is clearly not yet ready for commercialisation However concrete test facilities and prototypes
are being developed and solar fuels have already been produced at a laboratory scale The technology is not
yet sufficiently efficient in order to be able to compete with other technologies producing comparable
chemicals and fuels Finding catalysts which are on the one hand Earth-abundant non-toxic and inexpensive
and on the other hand sufficiently efficient seems to be the biggest challenge With respect to the
technological efficiency of the AP processes the main bottlenecks are light capture (whole spectrum) getting
a good photocurrent density and using these charge carriers efficiently87
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade In September 2014 Panasonic Corporation managed to achieve a conversion
efficiency rate of 03 becoming the first to exceed the rate of 02 for regular plants In November 2014
Toshiba reached 15 which was followed by 20 achieved by the Japan Technological Research
Association of Artificial Photosynthetic Chemical Process (ARPChem) in February 2015 In February 2016
Toyota Central RampD Labs Inc announced that they achieved the worldrsquos highest energy conversion
efficiency rate of 46 with artificial photosynthesis by developing a semiconductor substrates-using iridium
and ruthenium catalyst They succeeded in increasing the efficiency rate a hundred-fold (an efficiency rate of
004 had been in achieved by Toyota in 2011)88
Figure 47 summarizes these efficiency rate developments
Several companies (eg Toshiba) hint at achieving efficiency rates of 10 and the first practical applications
87
httpwwwosa-opnorghomearticlesvolume_24february_2013featuresartificial_photosynthesis_saving_solar_energy_for 88
httpswwwasiabiomassjpenglishtopics1603_01html
86
of AP in the 2020s ARPChem aims to achieve a 10 level of energy conversion efficiency in 2021 (the rate
at which the manufacturing of raw materials for chemicals becomes economically viable)89
Figure 47 Transition of energy conversion efficiency of artificial photosynthesis
Source httpswwwasiabiomassjpenglishtopics1603_01html
It can also be observed that the big industrial investors in AP technology (research) already built interesting
partnerships with research centres and new innovative start-upscompanies For example
Audi works together with the innovative company Joule Unlimited (US) on the development of biologically-
derived e-ethanol and e-diesel and also works together with start-up company Sunfire on the production
of synthetic diesel
Siemens works together with specialists at the University of Lausanne in Switzerland and at the University
of Bayreuth Germany on innovative catalysts
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University
(US) that works on the water-splitting and CO2 reduction process and
Mitsubishi is one of the five industrial partners in the Japanese ARPChem programme (2012-2021)
focusing on artificial photosynthesis research in which various Japanese universities will be involved
(including Waseda University and Tokyo University)
46 Summary of results and main observations
The aim of this report was to gain an understanding and a clear overview of the main European and global
actors active in the field of artificial photosynthesis This has been achieved by
Identifying the main European and global actors active in the field of AP
Providing an assessment of the current level of investments in AP technologies
Assessing the key strengths and weaknesses of the main actors and
Assessing the capabilities of the industry to develop and exploit the AP technologies
Fuelled by the globally perceived need to find a green non-polluting and emission neutral energy source for
the future there has been much development in the field of artificial photosynthesis and considerable progress
has been made In addition the emergence of multiple consortia and governmental programmes and
international conferences in the last 10-15 years suggest that there is a higher awareness of the potential of
89
httpwwwmitsubishichem-hdcojpenglishcsrdownloadpdf13_25pdf
87
AP and that further advances are necessary The analysis has shown that although there have been some
promising developments especially in collaboration with industry much remains to be done for AP
technologies and processes to become commercially viable Milestones which will spur the development and
commercialisation process of AP encompass increased global and industry cooperation and the deployment
of targeted large-scale innovation projects following the example of the US innovation hubs
A summary of the results of the analysis and the main observations concerning the research and industry
actors active in the field of artificial photosynthesis is presented below It should be noted that the academic
and industrial community presented in this report is not exhaustive and especially with increasing interest in
AP more actors are expected to become active in the field
Research community
In general we observe that AP research has been intensified during the last decade given the increasing
number of emerging networks and communities We identified more than 150 research groups on AP
worldwide out of which more than 60 are located in Europe Due to the interdisciplinary character of AP
research combines expertise from biology biochemistry biophysics and physical chemistry The development
of research networks and consortia facilitates collaboration between different research groups and enables
them to benefit from synergies We identified six consortia in Europe and five outside of Europe respectively
Almost all of them are based in a specific country attracting primarily research groups from that country Only
one consortium AMPEA launched by the European Energy Research Alliance is truly pan-European with a
range of members across the EU
Table 415 Summary of findings size of research community
Number of research groups
Total in Europe 113
Number of research groups per pathway
Synthetic biology amp hybrid systems 53
Photoelectrocatalysis 69
Co-electrolysis 25
Total outside Europe 77
Number of research groups per pathway
Synthetic biology amp hybrid systems 30
Photoelectrocatalysis 59
Co-electrolysis 14
Source Ecorys
With respect to the three technology pathways (synthetic biology amp hybrid systems photoelectrocatalysis and
co-electrolysis) we observed that almost 85 of the research activities worldwide are focused on the first two
pathways (about 34 on the first pathway and 50 on the second) whereas the third pathway attracts only
about 16 of the research communityrsquos attention Only the Dutch AP consortium BioSolar Cells specifically
focuses on co-electrolysis Other consortia like ARPChem in Japan collaborating with industry prefer to
research artificial photosynthesis via photoelectrochemical catalysis as this pathway is the most mature and
with the highest probability of successful commercialisation
The diversity of the scientists involved is the biggest strength of this global AP research community
Furthermore all of the existing technological pathways in AP are covered which avoids lock-ins into one
pathway and increases the probability of success for AP in general AP is on the research agenda of several
countries which is proven by the existence of dedicated programmes roadmaps and funds Globally several
hundreds of millions of euros are being spent this decade on AP research and these investments seem to be
intensifying further Major shortcomings encompass a lack of cooperation between research groups in
88
academia on the one hand and between academia and industry on the other A more technical challenge is
the transfer of scientific insights into practical applications and ultimately into commercially viable products
The AP sector in Europe exhibits some strengths in comparison to its non-European counterparts but also
some weaknesses Europersquos scientific institutions are strong and its researchers highly educated
Furthermore RampD institutions and research facilities are available providing a solid ground for research
Some individual MS have their own research programmes roadmaps and funds Nevertheless the investment
does not reach the amount of funds available in some non-European countries and is rather short-term in
comparison to that of its non-European counterparts Furthermore both the national research plans and their
funding seem fragmented and scattered lacking an integrated approach with common research goals and
objectives At the European level however collaboration has been successful within several ongoing and
conducted FP7 projects Close collaboration between research groups could also be achieved through the
establishment of consortia Apart from the pan-European consortium AMPEA collaboration between research
groups of different countries is limited the consortia are primarily country-based and attract mostly research
groups from that respective country Lastly the level of collaboration between academia and industry seems
to be more limited in Europe compared to that within the US or Japan
Industrial actors
At this moment the number of companies active in the field of AP is limited AP is still mainly at the laboratory
level Most pathways are still at level 1 or 2 of technology readiness (TRL) implying that research is still being
conducted and used to improve feasibility Only co-electrolysis is at a more advanced stage and most
methods are already commercially viable
Based on our analysis of the main AP actors in the industry only several tens of companies appear to be
active in this field Moreover the industrial activity is limited to research and prototyping as viable AP
technologies are not (yet) in commercial operation The pathways synthetic biology amp hybrid systems and
photoelectrocatalysis are still at the lowest levels of technology readiness Research within the
photoelectrocatalysis pathway is still at an early stage as well however PV devices (semiconductor devices
similar to the ones used in PEC devices) have already been successfully commercialised Co-electrolysis on
the other hand is a technology already available for a longer time period in this pathway various
technologies to convert water and DC electricity into gaseous hydrogen and oxygen are already
commercialised In contrast the technologies producing hydrocarbons by Fischer-Tropsch synthesis
converting for example CO2 H2O and syngas into hydrocarbon fuels are still at an earlier stage of
development Co-electrolysis is therefore at a 1-9 TRL having both already commercialised technologies as
well as the Fischer-Tropsch synthesis
In total we have identified and analysed 33 industrial actors active in the field of AP 15 European and 18 non-
European industrial actors With respect to the industry largely the same countries stand out as in the
research field namely Japan the US and north-western Europe The industry in Japan appears to have the
most intensive research activities in AP as several large Japanese multinationals have set up their own AP
RampD laboratoriesresearch departments With respect to the three technology pathways we can observe that
most industrial (research) activity is being performed concerning photoelectrocatalysis
89
Table 416 Summary of findings size of industrial community
Number of companies
Total in Europe 15
Number of companies per pathway
Synthetic biology amp hybrid systems 6
Photoelectrocatalysis 9
Co-electrolysis 1
Total outside Europe 18
Number of companies per pathway
Synthetic biology amp hybrid systems 3
Photoelectrocatalysis 11
Co-electrolysis 5
Source Ecorys
The main hurdles in the synthetic biology amp hybrid systems pathway relate to the improvement of efficiency
and protein production speeds as well as stability and solubility by rational design With respect to the
technological efficiency of the AP processes relating to photoelectrocatalysis the main bottlenecks are light
capture (whole spectrum) obtaining a good photocurrent density and using these charge carriers efficiently
Co-electrolysis is mainly facing challenges to increase the lifetime of the devices to create concept on a
megawatt scale to search for substitution of noble metal catalysts and to develop technologies that are
capable of supplying the electricity required Furthermore some methods are still at a low TRL like the
Fischer-Tropsch synthesis Finding catalysts which are Earth-abundant non-toxic inexpensive and
sufficiently efficient remains a huge challenge To this end more public and private funding is needed
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade For example between 2011 and 2016 Toyota Central RampD labs made a significant
leap forward from an efficiency rate of 004 towards an efficiency rate of 46 Furthermore several
industrial actors (including Toshiba and ARPChem) have hinted at being able to achieve efficiency rates of
10 and the first practical applications of AP in the 2020s When academia are able to overcome the main
barriers with respect to AP the TRL will increase and the interest in AP from the industries will rise More
interest from the industries is necessary in order to push AP on the market and making it an economically
viable alternative renewable energy source
91
5 Factors limiting the development of AP technology
The overall concept followed in this study is to assess a number of selected ongoing research technological
development and demonstration (RTD)initiatives andor technology approaches implemented by European
research institutions universities and industrial stakeholders in the field of AP (including the development of
AP devices)
Seven AP RTD initiatives have been identified for the assessment of ldquolimiting factorsrdquo addressing the three
overarching technology pathways synthetic biology amp hybrid systems photoelectrocatalysis of water (water
splitting) and co-electrolysis (see Table 51)
The authors are confident that through the assessment of these selected European AP RTD initiatives a good
overview of existing and future factors limiting the development of artificial photosynthesis technology (in
Europe) can be presented However it has to be noted that additional AP RTD initiatives by European
research institutions universities and industrial stakeholders do exist and that this study does not aim to prove
a fully complete inventory of all ongoing initiatives and involved stakeholders
Table 51 Overview of the selected AP research technological development and demonstration (RTD) initiatives
AP Technology
Pathways AP RTD initiatives for MCA
Synthetic biology amp
hybrid systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Biocatalytic conversion of CO2
into formic acid ndash Bio-hybrid
systems
Photoelectrocatalysis
of water (light-driven
water splitting)
Direct water splitting with bandgap absorber materials and
catalysts
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
a) Direct water splitting with III-
V semiconductor ndash Silicon
tandem absorber structures
b) Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Co-electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
Electrolysis cells for CO2
valorisation ndash Industry
research
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges
Until today much progress has been made in the development of artificial photosynthetic systems
However a number of significant scientific and technological challenges remain to successfully scale-up
existing laboratory prototypes of different AP technology approaches towards a commercial scale
In order to ensure that AP technologies become an important part of the (long-term) future sustainable
European and global energy system and additionally provide high-value and low carbon chemicals for
industrial applications AP based production systems need to be
Efficient so that they utilise as much sunlight as possible to produce fuels andor chemicals The larger
the fraction of sunlight that can be converted to chemical energy the fewer materials and less land would
be needed for AP devices A target efficiency of about 10 (for AP based fuel production) is an initial goal
This is about ten times the efficiency of natural photosynthesis however it should be noted that AP
92
laboratory prototype devices with solar-to-hydrogen efficiencies of 5 and more have already been
developed
Durable so that AP systems can convert a lot of energy in their lifetime relative to the energy required for
the production and installation of the devices This is a significant challenge because some materials
degrade quickly when operated under the special conditions of illumination by discontinuous sunlight
Cost-effective meaning the raw materials needed for the production of the AP devices have to be
available at a large scale and the produced fuels andor chemicals have to be of commercial interest
Resource-efficient so that they minimise the use of rare and expensive raw materials (taking into
account trade-offs between material abundancy cost and efficiency)
Today significant improvements with respect to cost-efficiency lifetimedurability energy efficiency and
resource use are still required for all existing AP technology approaches
Table 52 provides an overview of the current and target performance for the assessed seven AP research
technological development and demonstration (RTD) initiatives within the three overarching technology
pathways of synthetic biology amp hybrid systems photoelectrocatalysis and co-electrolysis
93
Table 52 Overview of the current and target performance with respect to cost-efficiency lifetimedurability energy efficiency and resource use
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
Nitrogenase
activity wanes
within a few
days
Light energy
conversion
efficiency
gt10
(theoretical
limit ~15)
4 (PAR
utilization
efficiency) on
lab level (200 x
600 mm)
No data No data
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
CO2 reduction
energy
efficiency (full
system) gt10
(nat PS ~1)
NA (CO2
reduction
energy
efficiency for
full system) on
lab level
No data No data
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
gt500 hours
(stability goal)
gt40 hours
Solar-to-
hydrogen
(STH)
efficiency
gt17
STH efficiency
14
Reduction of
use of noble
metal Rh
catalyst and
use of Si-
based
substrate
material
1kg Rh for
1MW
electrochem
power output
Ge substrate
(for
concentrator
systems)
Si substrate
94
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Bandgap abs materials
Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency ~9
STH efficiency
49
Reduction of
use of rare Pt
catalyst
Pt used as
counter
electrode for
H2 production
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency
gt10
IPCE gt90
(efficiency
goal)
IPCE (incident
photon to
electron
conversion
efficiency) of
25
Reduction of
use of rare and
expensive raw
materials
High-cost Ru-
based photo-
sensitizers
used
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
SOFC capital
cost target
400 US$kW
Comp of
synthetic fuels
with fossil fuels
No data
gt20 years
(long term)
1000 hours
(stability goal)
~50 hours
(high SOEC
cell
performance
degradation
observed)
Power-to-
Liquid system
efficiencies
(full system
incl FT)
gt70
No data No data No data
Electrolysis cells for CO2
valorisation ndash Industry
research
Comp with
fossil chemi
and fuels (eg
CO ethylene
alcohols) 650-
1200 EURMt
No data
gt20 years
(long term)
10000 hours
(stability goal)
gt1000 hours
(laboratory
performance)
System
efficiencies
(full system)
gt60-70
95 of
electricity used
to produce CO
System
efficiencies
(full system)
40
No data No data
95
52 Current TRL and future prospects of investigated AP RTD initiatives
Table 53 presents an overview of the current TRL future prospects and an estimation of future required
investments for the assessed AP research technological development and demonstration (RTD) initiatives
It should be noted that due to the focus on specific selected AP RTD initiatives the investment requirements
listed below do not represent all of the RTD activities conducted by European research institutions
universities and industrial stakeholders within the three overarching technology pathways of synthetic biology
amp hybrid systems photoelectrocatalysis and co-electrolysis
Table 53 Overview of current TRL future prospects and estimated investment needs for investigated AP RTD initiatives
AP RTD Initiatives TRL achieved (June
2016)
Future Prospects Estimated Investment
needed
Photosynthetic microbial cell
factories based on cyanobacteria
TRL 3 (pres Init)
TRL 6-8 (for direct
photobiol ethanol prod
with cyanobacteria green
algae)
2020 TRL 4 (pres Init)
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Biocatalytic conversion of CO2 into
formic acid ndash Bio-hybrid systems TRL 3 2020 TRL 4
Direct water splitting with III-V
semiconductor ndash Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 (for III-VGe
tandem structures)
TRL 3 (for III-VSi tandem
structures)
2020 TRL 5 (for III-VGe
tandem structures)
2021 TRL 5 (for III-VSi
tandem structures)
Basic RTD 5-10 Mio euro
TRL 5 5-10 Mio euro
Direct water splitting with Bismuth
Vanadate (BiVO4) - Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 2020 TRL 5
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
TRL 3 2020 TRL 4
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
TRL 2-3 (for co-
electrolysis of H2O
(steam) and CO2)
2020 TRL 3-4 (for co-
electrolysis of H2O
(steam) and CO2)
Electrolysis cells for CO2
valorisation ndash Industry research
TRL 4 (for RE assisted
carbon compound
production)
TRL 3 (for full synthetic
photosynthesis systems)
2020 TRL 6 (for RE
assisted carbon
compound production)
2020 TRL 5 (for full
synthetic photosynthesis
systems)
TRL 6 10-20 Mio euro
53 Knowledge and technology gaps of investigated AP RTD initiatives
At present a number of significant scientific and technological challenges remain to be addressed before
successfully being able to scale-up existing laboratory prototypes of different AP technology approaches
towards the commercial scale
Table 54 presents an overview of the identified knowledge and technology gaps focusing on the assessed
AP research technological development and demonstration (RTD) initiatives
96
Table 54 Overview of knowledge and technology gaps of investigated AP RTD initiatives
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Photosynthetic microbial cell
factories based on
cyanobacteria
Further metabolic and genetic engineering of the strains
Further engineered cyanobacterial cells with respect to increased light
harvesting capacity
Streamlined metabolism toward hydrogen production for needed electrons
proteins and energy instead of being used in competing pathways
More efficient catalysts with higher turnover rates
Simple and reliable production systems allowing higher photosynthetic
efficiencies and the use of optimal production conditions
Efficient mechanisms and systems to separate produced hydrogen from other
gases
Cheaper components of the overall system
Investigation of the effect of pH level on growth rate and hydrogen evolution
Production of other carbon-containing energy carriers such as ethanol
butanol and isoprene
Improvements of the photobioreactor design
Up-scaling of photobioreactor (from present active surface of 200 x 600 mm)
Improvement of operating stability (from present about gt100 hours)
Improvement of PAR utilisation efficiency from the present 4 to gt10
Cost reduction towards a hydrogen production price of 4 US$ per kg
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Further metabolic and genetic engineering of strains
Reduction of reactive oxygen species (ROS) which are detrimental to cell
growth
Development of biocompatible catalyst systems that are not toxic to bacteria
Development of ROS-resistant variants of bacteria
Development of hybrid systems compatible with the intermittent nature of the
solar energy source
Development of strains for CO2 reduction at low CO2 concentrations
Metabolic engineering of strains to facilitate the production of a large variety of
chemicals polymers and fuels
Enhance (product) inhibitor tolerance of strains
Further optimisation of operating conditions (eg T pH NADH concentration
ES ratio) for high CO2 conversion and increased formic acid yields
Integration of enzymes into the hydrogen evolving part of ldquobionic leafrdquo devices
Mitigation of bio-toxicity at systems level
Improvements of ldquobionic leafrdquo device design
Up-scaling of ldquobionic leafrdquo devices
Improvement of operating stability (from present about gt100 hours)
Improvement of CO2 reduction energy efficiency towards gt10
Cost reduction of the production of formic acids and other chemicals
polymers and fuels
97
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Increased understanding of surface chemistry at electrolyte-absorber
interfaces
Further improvement of functionalization to achieve higher stabilities without
the need for protective layers
Reduction of defects acting as recombination centres or points of attack for
(photo)corrosion
Reduction of pinhole formation leading to reduced mechanical stability of the
Rh catalyst
Reduction of the amount of rare and expensive catalysts by the use of core-
shell catalyst nanoparticles with a core of an earth-abundant material
Reduction of material needed as substrate by employment of lift-off
techniques or nanostructures
Deposition of highly efficient III-V tandem absorber structures on (widely
available and cheaper) Si substrates
Development of III-V nanowire configurations promising advantages with
respect to materials use optoelectronic properties and enhanced reactive
surface area
Reduction of charge carrier losses at interfaces
Reduction of catalyst and substrate material costs
Reduction of costs for III-V tandem absorbers
Development of concentrator configurations for the III-V based
photoelectrochemical devices
Improvement of device stability from present gt40 hours towards the long-term
stability goal of gt500 hours
Improvement of the STH production efficiencies from the present 14 to
gt17
Cost reduction towards a hydrogen production price of 4 US$ per kg
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Improvements of the light absorption and carrier-separation efficiency
(currently still at lt60) in BiVO4
Better utilization of the solar spectrum by BiVO4 especially for wavelengths
close to the band edge (eg by plasmonic- andor resonance-enhanced
optical absorption)
Further development of novel water-oxidation catalysts based on for example
cobalt- and iron oxyhydroxide-based materials
Further development of the distributed n+ndashn homojunction concept for
improving carrier separation in high-donor density photoelectrode material
Improvement of the stability and avoidance of mass transport and light
scattering problems in devices based on nanoporous materials and DSSC
(Dye Sensitised Solar Cells)
Further development of Pulsed Laser Deposition (PLD) for (multi-layered)
WO3 and BiVO4 photoanodes
Although the near-neutral pH of the electrolyte solution ensures that the BiVO4
is photochemically stable proton transport is markedly slower than in strongly
alkaline or acidic electrolytes
Design of new device architectures that efficiently manage proton transport
and avoid local pH changes in near-neutral solutions
For an optimal device configuration the evolved gasses need to be
transported away efficiently without the risk of mixing
The platinum counter electrode needs to be replaced by an earth-abundant
alternative such as NiMo(Zn) CoMo or NiFeMo alloys
Improvement of device stability from present several hours towards the long-
term stability goal of 1000 hours
Scaling up systems to square meter range
Improvement of the STH production efficiencies from the present 49 to ~9
Cost reduction towards a hydrogen production price of 4 US$ per kg
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Deep molecular-level understanding of the underlying interfacial charge
transfer dynamics at the SCdye catalyst interface
Novel sensitizer assemblies with long-lived charge-separated states to
Design and construction of functional DS-PECs with dye-sensitised
photoanodes and dye-sensitised photocathodes (tandem DS-PEC structures)
Design and construction of DS-PECs where undesired external bias is not
98
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
enhance quantum efficiencies
Sensitizerndashcatalyst supramolecular assembly approach appears as effective
strategy to facilitate faster intramolecular electron transfer for long-lived
charge-separated states
Optimise the co-adsorption for efficient light-harvesting and charge collection
Organometal halide perovskite compounds as novel class of light harvesters
(for absorber applications in DS-PEC)
Encapsulation of perovskite compounds to prevent the dissolution in aqueous
solutions
Semiconductor quantum dots (QDs) as suitable sensitizers for DS-PEC
Exploration of more efficient OERHER catalysts with low overpotentials
Use of a redox mediator analogous to the tyrosine-histidine pair in PSII to
accelerate dye regeneration and thus achieve an increased charge
separation lifetime
One-dimensional TiO2 nanostructures such as TiO2 nanotubes and nanorods
to improved the charge transport properties and thus charge collection
efficiencies
Exploration of alternative SC oxides with more negative CB energy levels to
match the proton reduction potential
Search for alternative more transparent p-type SCs with slower charge
recombination and high hole mobilities
Further studies on phenomena of photocurrent decay commonly observed in
DS-PECs under illumination with time largely due to the desorption andor
decomposition of the sensitizers andor the catalysts
needed
Design and construction of DS-PECs with enhanced quantum efficiency
(towards 90 IPEC)
Ensure dynamic balance between the two photoelectrodes in order to properly
match the photocurrents
Development of efficient photocathode structures
Ensure long-term durability of molecular components used in DS-PEC devices
Reduce photocurrent decay due to the desorption andor decomposition of the
sensitizers andor the catalysts
Ensure active photosensitizer and catalyst for at least millions of cycles in 20ndash
30 years
Ensure long operating lifetimes (such as achieved for DSC) for stable DS-PEC
devices that incorporate molecular components Future work on developing
robust photosensitizers and catalysts firm immobilization of sensitizercatalyst
assembly onto the surface of SC oxide as well as the integration of the robust
individual components as a whole needs to be addressed
Scaling up systems to square meter range
Improvement of the STH production efficiencies IPCE (incident photon to
electron conversion efficiency) need to be improved from ~25 to gt90
Cost reduction towards a hydrogen production price of 4 US$ per kg
99
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Basic understanding of reaction mechanisms in co-electrolysis of H2O (steam)
and CO2
Basic understanding of dynamics of adsorptiondesorption of gases on
electrodes and gas transfer during co-electrolysis
Basic understanding of material compositions microstructure and operational
conditions
Basic understanding of the relation between SOEC composition and
degradation mechanisms
Development of new improved materials for the electrolyte (eg Sr- and Mg-
doped lanthanum gallate (LSGM) and scandium-stabilized zirconia (Sc- SZ))
Development of new improved materials for the electrodes (eg Sr- and Fe-
doped lanthanumcobaltate (LSCF)Sr-doped lanthanum ferrite (LSF)Co-
and Nb-doped barium ferrite (BCFN) and Sr- and Fe-barium cobaltate
(BSCF) perovskites)
Avoidance of agglomeration of Ni-particles and micro-cracks in Ni-YSZ
hydrogen electrodes
Avoidance of mechanical damages (eg delamination of oxygen electrode) at
electrolyte-electrode interfaces
Reduction of carbon (C) formation during co-electrolysis
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Replacing metallic based electrodes by pure oxides
Studies of long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O (steam) and CO2
Improvement of stability performance (from present ~50 hours towards the
long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Improvement of the co-electrolysis syngas production efficiencies towards
values facilitating the production of competitive synthetic fuels via FT-
processes
Cost reduction towards competitiveness of synthetic fuels with fossil fuels
Electrolysis cells for CO2
valorisation ndash Industry
research
Further research on catalyst development
Investigation of catalyst surface structure (highly reactive surfaces)
Catalyst development for a variety of carbon-based chemicals and fuels
Research on electrolyte composition and performance (dissolved salts current
density)
Research on light-collecting semiconductor grains enveloped by catalysts
Research on materials for CO2 concentration
Careful control of catalyst manufacturing process
Precise control of reaction processes
Development of modules for building facades
Stable operation of lab-scale modules
Stable operation of demonstration facility
Improvement of production efficiencies for carbon-based chemicals and fuels
Cost reduction towards competitiveness of the produced carbon-based
chemicals and fuels
100
54 Coordination of European research
Although RTD cooperation exists between universities research institutions and industry from different
European countries the majority of the activities are performed and funded on a national level Thus at
present the level of cooperation and collaboration on a pan-European level seems to be limited
There are few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7
projects and many research groups that are operating locally and are funded by national governments A low
degree of collaboration among different research groups was reported which results in a duplication of efforts
and a lack of generalized standards Synergies which could potentially boost research in artificial
photosynthesis are being overlooked Creating for example a communication platform to facilitate exchange
among actors could more easily promote the development of knowledge and increase the speed of discovery
and exploitation of new robust (effective and durable) photocatalysts innovative processes and devices etc
Another indicated weakness is the lack of collaboration between the already existing and ongoing projects
The coordination of research at a European level is mainly performed by AMPEA The European Energy
Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials amp Processes for Energy
Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging Technologies Artificial
photosynthesis became the first energy research subfield to be organised within AMPEA The goal of this joint
programme which was launched at the end of 2011 is to set up a thorough and systematic programme of
directed research which by 2020 will have advanced the technology to a point where commercially viable
artificial photosynthetic devices will be under development in partnership with industry
Currently AMPEA does not involve biological AP approaches as its main mission focuses on advanced
materials Therefore opportunities for research cooperation in the field of synthetic biology seem limited in the
short term
Furthermore it was stated that the current effectiveness of AMPEA to coordinate research at a European level
is limited also due to budget constraints and limited direct funding provided to AMPEA
Specifically efforts within AMPEA are currently centred on developing a concise RTD roadmap for AP
technologies in Europe The future implementation of this roadmap will require support on both national and
European levels
Table 55 (below) presents a list of European research collaborations within the investigated AP research
technological development and demonstration (RTD) initiatives
101
Table 55 (European) research cooperation within the investigated AP RTD initiatives
AP RTD Initiatives (European) Research cooperation
Photosynthetic microbial
cell factories based on
cyanobacteria
Initiative implemented by Uppsala University Sweden (within CAP) in cooperation with
Norwegian Institute of Bioeconomy Research (NIBIO)
Existing cooperation between Uppsala University and German car manufacturer VW
Biocatalytic conversion of
CO2 into formic acid ndash
Bio-hybrid systems
Initiative implemented by Wageningen UR Food amp Biobased Research and Wageningen UR
Plant Research International The Netherlands (within BioSolar Cells)
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
III-V semiconductor ndash
Silicon tandem absorber
structures
Initiative implemented by TU Ilmenau the Institute for Solar Fuels at the Helmholtz-Zentrum
Berlin and the Fraunhofer Institute for Solar Energy Systems ISE and the California Institute
of Technology (Caltech)
Existing cooperation between TU Ilmenau and epitaxy technology providers Space Solar
Power GmbH and Aixtron SE
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
Bismuth Vanadate
(BiVO4) - Silicon tandem
absorber structures
Initiative implemented by the Institute for Solar Fuels at the Helmholtz-Zentrum Berlin and
two Departments at Delft University of Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Further RTD was done at Repsol Technology Center from Spain in cooperation with
Catalonia Institute for Energy Research (IREC)
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
Initiative implemented by KTH Royal Institute of Technology Sweden in cooperation with
Dalian University of Technology China (within CAP)
Further RTD at University of Amsterdam (within BioSolar Cells) University of Grenoble
University of Cambridge and EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Existing cooperation between OMV and University of Cambridge
Existing cooperation between Siemens and EPFL
Co-electrolysis of steam
and carbon dioxide in
Solid Oxide Electrolysis
Cells (SOEC)
RTD performed at Technical University of Denmark Imperial College London University of
Sheffield and in previous years by Catalonia Institute for Energy Research (IREC) in
cooperation with Repsol Technology Center from Spain
Electrolysis cells for CO2
valorisation ndash Industry
Research
Initiative implemented by Siemens Corporate Technology (CT) in cooperation with the
University of Lausanne and the University of Bayreuth Germany
55 Industry involvement and industry gaps
Due to the low TRL (TRL 2-4) of present AP technology pathways in the areas of synthetic biology amp hybrid
systems photoelectrocatalysis of water (water splitting) and co-electrolysis the direct involvement of industry
in research and development activities in Europe is currently limited
Furthermore detailed information on industry activities in the AP field is difficult to find also due to issues of
confidentiality According to Cefic (European Chemical Industry Council) AP is regarded as a potentially
promising future technology option by the Councilrsquos members however information on industry involvement is
largely kept confidential
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research including
research in artificial photosynthesis However while companies are participating in local consortia such as
BioSolar Cells there currently seems to be a lack of cooperation between academia and industry at an
international level
102
Industry involvement in the area of synthetic biology amp hybrid systems
There is ongoing cooperation between Uppsala University and the German car manufacturer Volkswagen
within the framework of the European project ldquoPhotoFuelrdquo The project is coordinated by VW and focuses on
the production of butanol using micro-organisms
The European industry end users Volvo and VW are involved in the field of the design and engineering of
photosynthetic microbial cell factories based on cyanobacteria however are not directly involved in the
development of micro-organisms themselves
Furthermore in the USA the company Algenol Biofuels Inc is active in the field and operating a pilot scale
production unit
Industrial partners potentially interested in the development of ldquobionic leavesrdquo include the industry partners of
the Dutch BioSolar Cells programme Currently the coupling of the developed enzymes to the hydrogen-
evolving part of the device (ie the development of a full ldquobionic leafrdquo) is subject to ongoing patent procedures
by researchers of Wageningen UR
Industry involvement in the area of photoelectrocatalysis of water (water splitting)
The processes used for the deposition and processing of the devices based on two-junction tandem absorber
structures namely the metal-organic vapour phase epitaxy (MOCVD) and the in-situ functionalisation of
surfaces are generally scalable to an industrial level Spray pyrolysis processes used for the deposition of
dense thin films of BiVO4 are well-established industrial technologies and thus generally scalable to an
industrial level
Industrial stakeholders potentially interested in the area of direct water splitting with tandem absorber
structures include industry partners active in the field of epitaxy technology (eg producers and technology
providers such as Azur Space Solar Power GmbH and Aixtron SE which have ongoing long-term cooperation
with TU Ilmenau) suppliers of industrial process and specialty gases (eg Linde Group) and chemical
industries involved in catalytic processes (eg BASF Evonik)
Further interested industrial stakeholders include industry partners of the network Hydrogen Europe
(httphydrogeneuropeeu) and the Fuel Cells and Hydrogen Joint Undertaking (FCH JU
httpwwwfcheuropaeu) Hydrogen Europe (formerly known as NEW-IG) is the leading industry association
representing almost 100 companies both large and SMEs working to make hydrogen energy an everyday
reality The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) is a unique public-private partnership
supporting RTD activities in fuel cell and hydrogen energy technologies in Europe
The industry player Repsol from Spain was involved (on a research and development level) in the
development of photoelectrochemical water splitting based on metal oxides (WO3 BiVO4) through its Repsol
Technology Center in Spain in cooperation with the Department of Advanced Materials for Energy Catalonia
Institute for Energy Research (IREC) and the Department of Electronics University of Barcelona (UB) The
focus is currently centred on Pulsed Laser Deposition (PLD) for (multi-layered) WO3 and BiVO4 photoanodes
No full devices for photoelectrochemical water splitting have however yet been reported within this initiative
In the area of dye-sensitised PEC potentially interested industrial partners include the major fuel companies
Shell and Total who are already members of SOFI (Solar Fuels Institute based at Northwestern University)
an international research and innovation organisation with several European members (including the core
member Uppsala University) The Austrian fuel company OMV funds research at the Reisner Lab at the
Department of Chemistry at the University of Cambridge which is involved in both dye and catalyst
development
103
Successful technology transfer has recently been reported by Innovation Exchange Amsterdam (IXA) the
technology transfer office of the University of Amsterdam to the French company PorphyChem Rights were
licensed for the commercialisation of novel molecules for hydrogen generation so-called metalloporphyrins
innovative molecular photosensitizers which enable sustainable sunlight-driven hydrogen production from
water In cooperation with IXA the researchers filed patent applications with the European Patent Office on 26
February 2015 H-C Chen A M Brouwer Photosensitizer Europatent application 2015 EP15156740
The industry player Siemens AG from Germany is funding a project implemented by the Laboratory of
Photonics and Interfaces the Institute of Chemical Sciences and Engineering the School of Basic Sciences
and the Ecole Polytechnique Federale de Lausanne (EPFL) for the development of efficient photosynthesis of
carbon monoxide from CO2 using perovskite photovoltaics
Industry involvement in the area of co-electrolysis
Until today the involvement of industry in the research and development of the co-electrolysis of water and
carbon dioxide in Solid Oxide Electrolysis Cells (SOECs) in Europe is limited
Activities (on a research and development level) were performed by the industry player Repsol from Spain
through its Repsol Technology Center in cooperation with the Department of Advanced Materials for Energy at
the Catalonia Institute for Energy Research (IREC) The focus of these efforts is the replacement of metallic-
based electrodes by pure oxides offering advantages for industrial applications of solid oxide electrolysers
Thereby the aim is to ensure suitable H2CO ratios of the produced syngas (ie close to two) fulfilling the
basic requirements for synthetic fuel production
At present the focus of industrial engagement (eg sunfire Audi) for the production of synthetic carbon-based
fuels via concepts using (co)electrolysis and FT-processes favours water electrolysis (for the production of H2)
and the separate addition of CO2 in the FT-process over co-electrolysis of water and carbon dioxide
In April 2015 the company sunfire GmbH announced that it succeeded in producing synthetic diesel from air
water and green electrical energy A demonstration rig for power-to-liquids was inaugurated in November
2014 Recently the plant reached its full operating capacity and now produces synthetic diesel fuel Audi the
German car manufacturer and project partner of sunfire exposed the synthetic diesel to laboratory tests with
the result that the fuel was approved A larger plant needs to be developed in order to proceed towards a
commercial application of this process
An industry-driven approach towards the valorisation of carbon dioxide for the production of carbon-based
chemicals and fuels is implemented by Siemens Corporate Technology (CT) in Munich Germany This work is
implemented within the framework of the Siemens corporate project ldquoCO2toValuerdquo where catalyst
development is performed in cooperation with researchers from the University of Lausanne in Switzerland and
materials scientists at the University of Bayreuth
A small-scale lab unit based on an electrolyser cell is currently in operation at Siemens CT and a large-scale
demonstration facility is planned to be operational in the coming years in order to pave the way towards the
industrial application of this synthetic photosynthesis process for the production of carbon-based chemicals
and fuels to be introduced into the market
104
56 Technology transfer opportunities
The transfer of research to industrial application in artificial photosynthesis remains challenging In order to
attract the attention of the private sector artificial photosynthetic systems have to be cost-effective efficient
and durable The active involvement of industrial parties could help bring research prototypes to
commercialisation This step towards commercialisation requires sufficient critical mass and funding however
which cannot be borne by a single country
In the framework of the assessment of the seven AP technology approaches in the areas of synthetic biology
amp hybrid systems photoelectrocatalysis of water (water splitting) and co-electrolysis a number of ongoing
collaborations between research organisations and the industry as well as future opportunities for technology
transfer have been identified
Technology transfer opportunities in the area of synthetic biology
There are ongoing patent procedures by researchers at Wageningen UR on the coupling of developed
enzymes to the hydrogen-evolving part of the device (ie the development of a full ldquobionic leafrdquo)
Technology transfer opportunities in the area of photoelectrocatalysis of water (water splitting)
There are several patents filed by the researchers of TU Ilmenau and a patent on full device for direct
water splitting with III-V semiconductor based tandem absorber structures is under development
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC) and University of Barcelona (UB)
Successful technology transfer has been achieved by the technology transfer office of the University of
Amsterdam to the French company PorphyChem rights were licensed for the commercialisation of
metalloporphyrins as novel molecules for hydrogen generation which enable sustainable sunlight-driven
hydrogen production from water patent applications have been filed with the European Patent Office
There are technology transfer opportunities between OMV and the University of Cambridge and between
Siemens and EPFL on perovskite PV
Technology transfer opportunities in the area of co-electrolysis
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC)
There are technology transfer opportunities between Siemens and the University of Lausanne as well as
the University of Bayreuth
Table 56 below provides and overview of industry involvement and technology transfer opportunities
105
Table 56 Overview of industry involvement and technology transfer opportunities
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Uppsala University Sweden (within
CAP) in cooperation with Norwegian
Institute of Bioeconomy Research
(NIBIO)
Existing cooperation between Uppsala University
and German car manufacturer VW
Interest by end users Volvo and VW
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Wageningen UR Food amp Biobased
Research and Wageningen UR
Plant Research International The
Netherlands (within BioSolar Cells)
Industry partners of BioSolar Cells
Ongoing patent procedures by researchers of
Wageningen UR on the coupling of the developed
enzymes to the hydrogen evolving part of the
device (ie the development of a full ldquobionic leafrdquo)
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
TU Ilmenau Institute for Solar Fuels
at the Helmholtz-Zentrum Berlin and
the Fraunhofer Institute for Solar
Energy Systems ISE and the
California Institue of Technology
(Caltech)
Existing cooperation between TU Ilmenau and
epitaxy technology providers Space Solar Power
GmbH and Aixtron SE
Interest by suppliers of industrial gases (eg
Linde Group) and chemical industries involved
in catalytic processes (eg BASF Evonik)
Industry partners of network Hydrogen Europe
and the Fuel Cells and Hydrogen Joint
Undertaking (FCH JU)
Several patents filed by researchers of TU
Ilmenau
Patent on full device for direct water splitting with
III-V thin film based tandem absorber structures
under development
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Institute for Solar Fuels at the
Helmholtz-Zentrum Berlin two
Departments at Delft University of
Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
Further RTD at Repsol Technology
Center from Spain in cooperation
with Catalonia Institute for Energy
Research (IREC) and University of
Barcelona (UB)
RTD by Repsol Technology Center focus is
currently placed on Pulsed Laser Deposition
(PLD) for (multi-layered) WO3 and BiVO4
photoanodes No full devices for
photoelectrochemical water splitting have
however yet been reported
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC) and University of Barcelona (UB)
Dye-sensitised
photoelectrochemical cells -
molecular photocatalysis
KTH Royal Institute of Technology
Sweden in cooperation with Dalian
University of Technology China
Existing cooperation between OMV and
University of Cambridge
Existing cooperation between Siemens and
Successful technology transfer by technology
transfer office of University of Amsterdam to the
French company PorphyChem Rights were
106
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
(within CAP)
Further RTD at University of
Amsterdam (within BioSolar Cells)
University of Grenoble University of
Cambridge and EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
EPFL
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Fuel companies Shell and Total
licensed for the commercialisation of novel
molecules for hydrogen generation so-called
metalloporphyrins innovative molecular
photosensitizers which enable sustainable
sunlight-driven hydrogen production from water
Patent applications filed with the European Patent
Office
Technology transfer opportunities between OMV
and University of Cambridge and between
Siemens and EPFL on perovskite PV
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Technical University of Denmark
Imperial College London University
of Sheffield and Catalonia Institute
for Energy Research (IREC) in
cooperation with Repsol Technology
Center from Spain
RTD by Repsol Technology Center focus is the
replacement of metallic based electrodes by
pure oxides offering advantages for industrial
applications of solid oxide electrolysers
Sunfire and Audi (steam electrolysis and FT-
synthesis)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC)
Electrolysis cells for CO2
valorisation ndash Industry
research
Siemens Corporate Technology (CT)
in cooperation with the University of
Lausanne and the University of
Bayreuth Germany
Industry driven approach towards the
valorisation of carbon dioxide for the production
of carbon-based chemicals and fuels by
Siemens CT
Technology transfer opportunities between
Siemens and University of Lausanne University of
Bayreuth
107
57 Regulatory conditions and societal acceptance
The current very low oil prices as well as the low carbon price (ie the fee that must be paid for the right to
emit CO2 into the atmosphere) are hindering the market uptake of the low carbon AP-based production of
chemicals polymers and fuels (carbon-based fuels as well as hydrogen) In addition until today carbon
benefits are only monetised in the energy sector and not for the production of eg low carbon chemicals
Furthermore direct market incentives for solar fuels may be an opportunity for the future development of AP
technologies In addition investments made towards the establishment of a European infrastructure for
hydrogen storage and handling may be beneficial for the future development of AP technologies
Advancements in artificial photosynthesis have the potential to radically transform how societies convert and
use energy However their successful development hinges not only on technical breakthroughs but also on
the acceptance and adoption by energy users
It is therefore important to learn from experiences with other energy technologies (eg PV wind energy
nuclear energy biofuels) and thoroughly involve all societal actors in a discussion on the potential benefits
and drawbacks of the emerging technology already during the very early stages of development
Specifically barriers to social acceptance and issues causing public concern need to be addressed in an open
dialogue and potential measures mitigating concerns need to be discussed and implemented (where
possible) It needs to be kept in mind that the majority of the public is largely unaware of AP technologies
The following main topics are subject to public concern with respect to present AP technology pathways in the
areas of synthetic biology amp hybrid systems photoelectrocatalysis of water (water splitting) and co-
electrolysis
The use of genetic engineering and Genetically Modified Organisms (GMO) mainly for synthetic biology
approaches
The use of toxic materials for the production of AP devices which concerns all pathways
The use of rare and expensive raw materials for catalysts and absorber materials also for all pathways
Land use requirements for large-scale deployment of AP technology and land use competition with other
renewable energy options such as PV solar thermal applications and bioenergybiofuels
High societal costs involved in the development of AP technologies (efficiency and competitiveness of AP
technologies)
The importance of societal dialogue within the future development of AP technologies is widely acknowledged
within several national initiatives in Europe Initiatives on public involvement are implemented within the Dutch
BioSolar Cells programme and by the German National Academy of Science and Engineering (acatech)
109
6 Development roadmap
61 Context
611 General situation and conditions for the development of AP
Current energy technologies are unlikely to be sufficient to attain EU ndash and other international ndash long term
targets for the share of renewable energy sources in overall energy supplies beyond 2020 There is therefore
a strategic interest in supporting efforts to develop new energy technologies (and improve existing ones) and
to raise their competitiveness ndash eg in terms of costs efficiency and resource use ndash vis-agrave-vis those that are
currently available Thus from an energy policy perspective the motivation for accelerating the industrial
implementation of AP technologies arises from their potential to expand the available portfolio of competitive
sustainable energy sources thereby contributing to the continuation of the transition away from fossil fuels At
the same time from the perspective of growth and job creation developing and demonstrating the viability and
readiness for industrial deployment of AP technologies can be viewed as part of a wider industrial policy to
develop an internationally competitive European renewable energy technology industry
Processes based on AP have been identified as having the potential to deliver sustainable alternatives to
conventional fuels AP-based lsquowater-splittingrsquo processes may be used for the production of hydrogen or in
combination with lsquocarbon reductionrsquo for the production of carbon-based fuels (lsquosolar fuelsrsquo) and other higher
order carbon-based compounds However although AP technologies show great potential and despite the
significant progress in research in the AP field made in recent years there is still a significant way to go before
AP technologies are ready for industrial implementation
AP covers several technology pathways that are being developed in parallel and which are all at a low overall
level of technology readiness The individual processes sub-systems and components within the different
pathways are however at varying levels of maturity Consequently it is difficult to foresee the eventual
production efficiency costs and material requirements that could characterise future AP-based systems when
implemented on an industrial scale Moreover while it is possible that some AP technologies may end up
competing with each other complementarities and synergies may arise from AP technology development
activities that are currently being conducted largely in isolation from each other
To date application of AP has only been undertaken in small scale in laboratory conditions and the feasibility
of commercial industrial-scale deployment of AP systems has yet to be demonstrated Assuming that this can
be achieved at cost levels that enable AP-based products to be competitive in the marketplace commercial
implementation may raise some more practical issues for example in relation to land-use water availability
and other possible environmental or social concerns that have not as yet been fully explored
To appreciate the possible future role of AP technologies also requires consideration of other developments
shaping the energy supply and technology landscape Although by definition AP is concerned with the direct
conversion of solar energy into fuel technologies for specific processes developed within the context of AP
may eventually be linked to other renewable energy technologies for example if they are combined with
electricity generated from photovoltaics (PV) or other renewable sources such as wind energy Similarly the
production of lsquosolar fuelsrsquo using AP systems requires a source of carbon which may come in the form of CO2
from ambient air or alternatively by linking AP to carbon capture (and storage) systems90
90
See for example DG Research (2015) ldquoProceedings of the scoping workshop Transforming CO2 into value for a rejuvenated European economy Brussels 26th March 2015rdquo
110
Prospects for the future industrial implementation of AP technologies will not only depend on the lsquopushrsquo
provided by technological developments but will also depend on market lsquopullrsquo factors Not least the
commercial viability of fuels produced using AP technologies (and other renewable energy sources) will be
strongly influenced by price developments for other fuels particularly oil Current low oil and carbon
(emissions) prices must be taken into consideration as factors potentially hindering the market uptake of low
carbon AP-based production of chemicals polymers and fuels (including hydrogen) both now and in the
future
The overall market potential of solar fuels will also depend on public policy developments for example in
terms of regulatory frameworks and incentives affecting demand levels and costsprices of renewable energy
sources Similarly a concerted policy framework targeted towards promotion of a lsquohydrogen economyrsquo may
lead to a shift in emphasis for AP technology development towards hydrogen production (lsquowater splittingrsquo) ndash
already the more advanced area of AP research ndash and away from solar fuels Certainly until a higher
technology readiness level of AP is attained care should be taken to ensure that regulatory measures ndash
whether at European and national levels ndash do not impinge upon or hinder developments along the different AP
pathways
Finally in order to truly accelerate the industrial implementation of AP social acceptance and adoption of the
new technology by energy users must be acquired As it stands the majority of the public is largely unaware
of the development and significance of AP while those who are voice concerns about genetic engineering the
use of toxic materials the use of rare and expensive raw materials and the high societal costs involved in the
development along all technology pathways
612 Situation of the European AP research and technology base
Europersquos scientific communities form more than 60 of the 150 or so research groups on AP worldwide
boasting well-educated researchers and a diverse range of scientists - an interdisciplinary approach being
crucial for scientific advancement within this highly innovative field Together these groups cover all of the
identified existing technological pathways along which the advancement of AP might accelerate thus
increasing the likelihood of cooperation between European scientists with possible breakthroughs on any
given path
Significant improvements are still needed with respect to cost-efficiency lifetimedurability energy efficiency
and resource use for all existing AP technologies and progress is being made in addressing these knowledge
and technology gaps Yet while this technological development making strides along multiple pathways
simultaneously shows a considerable amount of potential the scientific community alone cannot accelerate
the development of the industrial implementation of AP Aiding the development from a currently low
technology readiness level and eventually commercialising AP will involve a host of enabling factors
including those of the financial structural regulatory and social nature
As it stands currently European investment into AP technologies falls short of the amounts being dedicated in
a number of non-European countries and it could be argued is rather short-term if not short-sighted Further
stifling the potential of these technologies is the fact ndash significant considering most European research activity
into AP operates at a national level (only one of the six consortia in Europe being pan-European) ndash that both
national research plans and their funding are fragmented lacking a necessary integrated approach Adding to
this fragmentation there appears to be a lack of cooperation between research groups and academia on the
one hand and between academia and industry on the other This suggests that there are some structural
barriers impeding the speed and success of the development and eventual commercialisation of AP in
Europe
111
Accelerating the development of AP requires bringing the best and brightest to the forefront of the research
being carried out in the field which would in turn involve a conscious effort to boost collaboration of the top
contributors across Europe - such an effort has been the cluster of several FP7 projects the good example of
which may well serve as a foundation on which to build in the future Once the divide between research
groups and academia has been breached and the technological advancement of AP technologies has been
given the push needed to be able to climb higher up the TRL scale interest from and in turn collaboration with
the industry should rise
62 Roadmap overview
The assessment of the existing lsquostate of the artrsquo undertaken for this study reveals that AP technologies are in
general currently at relatively low levels of technology readiness levels91
There are many outstanding gaps in
fundamental knowledge and technology that must be addressed before AP can attain the level of development
necessary for industrial scale implementation Moreover there is not as yet any compelling evidence to
suggest that any particular AP pathway or sub-approach therein can currently be identified as clearly lsquomore
promisingrsquo than another Given this situation it seems appropriate at least for the time being to adopt an
lsquoopenrsquo approach to possible support measures for AP-related research efforts which does not single out and
prioritise any specific AP pathway or sub-approach This conclusion corresponds to the broad consensus view
expressed by participants at the workshop on lsquoArtificial Photosynthesis in Horizon 2020rsquo held in May 2016
Notwithstanding the above assessment if AP is to establish a role in the overall portfolio of energy sources
then the longer-term objective must be to develop competitive and sustainable AP technologies that can be
implemented at an industrial scale Thus a technology development roadmap for AP must support the
transition from fundamental research and laboratory-based validation through to demonstration at a
commercial or near commercial scale and ultimately industrial replication within the market Upscaling of
technologies and integration of processes in a complete lsquovalue chainrsquo ie from light harvesting through to
solar fuel (and other AP-based products) will require greater levels of investment and inevitably will imply
making choices on which technology options to prioritise As the general aim (of the roadmap) is to accelerate
industrial implementation these choices should reflect market opportunities for commercial application of AP
technologies while bearing in mind the overarching policy objectives of increasing the share of renewable
energy sources in overall energy supplies
621 Knowledge and technology development
Following from the above in terms of knowledge and technology development activities the outline roadmap
for support for the development of AP technologies consists of three phases as illustrated in Figure 61 and
described in more detail in the following sub-sections
91
Although the situation of with respect to different process varies most are assessed to be only at TRL 3 or 4 (ie corresponding to lsquoexperimental proof of conceptrsquo or lsquotechnology validated in labrsquo)
112
Figure 61 General development roadmap visualisation
Phase 1 Phase 3Phase 2
Regional MS amp EU
Regional MS EU amp Private
Private amp EU
Private (companies)
FUNDINGSOURCE
TRL 9Industrial
Implementation
TRL 6-8Demonstrator
Projects
Pilot ProjectsTRL 3-6
TRL 1-3Fundamental
Research
RampDampI ACTIVITIES
2017 2025 2035
113
In the following description for convenience the timeline for activities is addressed in three distinct phases It
should be noted however that some AP technologies are more advanced than others and that they
accordingly could already be at or close to readiness for pilot projects (addressed under Phase 2)
Accordingly some laboratory-based validation (TRL 4) and lsquorelevant environmentrsquo validation projects (TRL 5)
may be envisaged within Phase 1 of the Roadmap Conversely as all fundamental knowledge and technology
issues will be not be solved within the 5-7 year time horizon foreseen for Phase 1 the need to support such
development through smaller scale research projects can be expected to continue into Phase 2 of the
Roadmap and possibly beyond
Furthermore in addition to support for fundamental knowledge and technology development the Roadmap
foresees the need to integrate lsquosupporting and accompanying activitiesrsquo (see Section 622) These activities
should run in parallel to the support for knowledge and technology development with initial activities starting
within Phase 1 of the Roadmap and continuing throughout the entire period of the Roadmap It may be
appropriate that some of the suggested activity areas are addressed as part of the proposed Networking
action (Action 2) and Coordinating action (Action 5)
Phase 1 - Time horizon short term (from now to year 5-7)
This phase will target the continuation of early stage research on AP technologies in parallel with initiation of
the process of scaling-up from laboratory based bench-scale projects towards pilot scale projects (ie to
validate whether bench scale projects are viable at a pilot scale) In keeping with the general status of AP
knowledge and technology development the scope of support during this phase should remain lsquoopenrsquo to all
existing (and potential) AP technology pathways and sub-options therein Such an approach should allow for
continued long-term advances in underpinning rsquogenericrsquo scientific knowledge that may lead to a breakthrough
in terms of newnovel approaches for AP while at the same time pushing forward towards addressing
technology challenges across the broad spectrum of AP pathwaysapproaches Notwithstanding this lsquoopenrsquo
approach eventual support may be directed towards specific topics that have been identified as areas where
additional effort is required to address existing knowledge and technology gaps
Under Phase 1 possible EU funding support should a priori be directed towards multiple small scale projects
(eg euro 3-5 million) that can complement existing regional and national programmes (and existing related EU-
level support)
Phase 1 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 1)
Recommendation Support for multiple small AP research projects
Objective To address outstanding gaps in fundamental knowledge and technology relating to AP
Rationale There are many remaining outstanding gaps in AP-relevant fundamental knowledge and
technology that must be addressed before AP systems can attain the level of development
necessary for industrial scale implementation This requires continued efforts dealing with
fundamental knowledge aspects of AP processes together with development of necessary
technology for the application of AP
Resources needed Project funding indicative cost circa euro 3-5 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact Strengthen diversify and accelerate knowledge and technology development for
processesdevices for AP-based production of hydrogen (water splitting) and carbon-based lsquosolar
fuelsrsquo
Priority
High
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
114
Recommendations to support knowledge and technology development (Action 2)
Recommendation Support for enhanced networking for AP research and technology development
Objective To improve information exchange cooperation and collaboration so as to increase efficiency and
accelerate AP-relevant knowledge and technology development towards industrial scale
implementation
Rationale AP research and technology development requires expertise across multiple and diverse
scientific areas both theoretical and applied Notwithstanding existing efforts to support and
enhance European AP research networks (eg AMPEA and precursors) AP research efforts in
the EU are fragmented being to a large extent organised and funded at national levels Further
development of EU-wide (and globally integrated) network(s) would promote coordination and
cooperation of research efforts within the AP field and in related fields addressing scientific
issues of common interest This action ndash offering secure funding for networking activities at a
pan-European level ndash should raise collaboration and increase synergies that potentially are being
currently overlooked
The broader international dimension of AP research and technology development could also be
addressed under this action In particular to develop instruments to facilitate research
partnerships beyond the EU (eg with US Japan Canada etc)
Resources needed Network funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact By providing a platform for knowledge exchange the speed of discovery and exploitation of
knowledge and technology developments should be accelerated both within the research
community and with industry
Priority
Medium
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
Recommendations to support knowledge and technology development (Action 3)
Recommendation AP Inducement Prize
Objective To provide additional stimulus for research technology development and innovation in the field
of AP while also raising awareness amongst the public and other stakeholders
Rationale The inducement prize would a priori target ldquoproof of conceptrdquo of AP at a bench-scale that meet
eligibility and award criteria set for the prize Experience suggests that lsquoinducement prizersquo
schemes can be particularly effective in situations corresponding to those of AP (ie where there
are a number of competing emergent technologies in the TRL 2-4 range that can potentially
deliver similar outcomes) The prize should provide an incentive for researchers to accelerate AP
RampD efforts and also potentially extend interest beyond the current AP research base to a wider
range of potential researchersinnovators
Resources needed Financial prize circa euro3 million
Prize organisation etc euro03 million
Actors involved Funding sources EU possible national (MS) contribution
Potential prize recipients Research and technology development institutions and (possibly)
industry
Expected impact Increased research intensity and wider participation resulting in turn to sooner than otherwise
demonstration of bench-scale AP devices This should provide for an earlier transition from
laboratory based research towards pilot projects
Priority
Medium
Suggested date of implementation92
Short (Phase 1)
92
Based on views gathered by the study there appears to be a general consensus that 3-4 years could be sufficient for the inducement prize contest timeframe Extending the timeframe for a longer period risks prize fatigue where contestants lose sight of the original prize aim and interest can start to wane
115
Phase 1 - Milestones
The scope of knowledge and technology development activities envisaged under Phase 1 is potentially very
broad as it covers multiple lsquopathwaysrsquo and a wide array of challengesissues ranging from general to highly
specific These concern each of the main AP steps (eg light harvesting charge separation water splitting
and fuel production) and range from materials issues device design and supporting activities such as process
modelling In general terms key criteria for evaluating overall progress towards the ultimate objective of
commercial implementation will revolve around factors such as efficiency of conversion of light into solar fuels
alongside the durability and potential cost-effectiveness of AP systems Shorter-term targets (lsquomilestonesrsquo)
could be set for minimum performance levels in terms of conversion efficiency (eg 10 conversion of solar
energy to hydrogen or to carbon-based fuels) although given the variation in progress across AP pathways
variable efficiency targets for individual pathways would seem appropriate
However if the purpose of the milestone is to mark the point of transition from Phase 1 to Phase 2 of the
Roadmap then a pragmatic milestone may be defined in terms of the development of an AP devicesystem
able to produce a lsquouseablersquo quantity of solar fuel in laboratory conditions sufficient to warrant further
development towards a pilot projectplant (Phase 2) In this regard it may make sense to a greater or lesser
degree to align the milestones for Phase 1 to the award criteria retained for the proposed inducement prize
Phase 2 - Time horizon medium term (from year 5-7 to year 10-12)
This phase will focus on reinforcing the implementation of pilot scale projects while initiating the process of
scaling up to a demonstration scale The scope of eventual support should focus on a limited number of
projects for the most promising AP technologies in order to demonstrate their viability at a pilot scale In this
context public (EU) funding support should be directed towards a limited number of medium scale projects At
the same time there should be encouragement of private sector participation in technology development
projects
Phase 2 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 4)
Recommendation Support for AP pilot projects
Objective To develop AP devices and integrated systems moving from laboratory scale up to an
(industrial) relevant scale of production This should enable comparative assessment of different
AP technology approaches at a production scale permitting industrial actors to make a
meaningful assessment of their potential viability for commercial deployment Equally these
projects should serve to identify (priority) areas where additional knowledge and technology
development is required in order to achieve industrial scale implementation
Rationale To reach industrial implementation of AP the feasibility of upscaling from laboratory conditions to
those approaching actual operational conditions needs to be demonstrated Accordingly pilot
projects under this Action item should provide for the testing and evaluation of AP devices to
assess and demonstrate the feasibility of reaching necessary characteristics (eg efficiency
levelstargets durabilitylife-cycle cost effectiveness) for commercial application for the
production of solar fuels The implementation of flexible pilot plants with open access to
researchers and companies should support (accelerated) development of manufacturing
capabilities for AP devices and scaling-up of AP production processes and product supply
Resources needed Project funding indicative cost circa euro 5-10 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Strengthen and accelerate knowledge and technology development for processesdevices for
AP-based production of hydrogen (water splitting) and carbon-based lsquosolar fuelsrsquo
Priority
High
Suggested date of implementation
Medium (Phase 2)
116
Recommendations to support knowledge and technology development (Action 5)
Recommendation Support for AP coordination
Objective To enhance efficiency (and effectiveness) of AP research efforts and more broadly to raise
coordination in the fields of solar fuels and energy technology development
Rationale There is a general need to ensure that research budgets are used effectively and to avoid
duplication of research effort In the context of AP there is a need to identify lsquomost promisingrsquo
technologies and set common priorities accordingly Moving to a common European AP
technology development strategy will require inter alia alignment of national research efforts in
the EU and (possible) cooperation at a broader international level Equally with the aim of
accelerating industrial implementation of AP there is a need to ensure cooperation and
coordination between research and technology development activities among the lsquoresearch
communityrsquo and industry
Resources needed Networkcoordination funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Improved coordination of AP research activities at European level (and possibly international
level) and improved priority setting to address knowledge and technology gaps for AP-based
processes and products
Priority
High
Suggested date of implementation
Medium (Phase 2) with possibility to extend implementation over
long term
Phase 2 - Milestones
The purpose of the AP pilot projects proposed under Phase 2 is inter alia to develop AP production
devicessystems operating at a sufficient scale to assess their potential viability for commercial deployment
Thus AP devicessystems developed within the pilot projects should attain sufficient performance levels and
fulfil basic operational and other characteristics (eg conversion efficiency lifetimedurability
sustainabilityresource use and cost-effectiveness) that are sufficient to attract the potential interest of private
sector (industry) investors Specific milestones for AP pilot projects may therefore be set in terms of multiple
target technical performance requirements but the overarching target lsquomilestonersquo for pilot projects will relate to
the overall assessment of their potential economic (commercial) viability conditional on further technological
developments (including engineering) and subject to their potential to comply with sustainability and other
social requirements
As a bottom line in terms of marking the point of transition from Phase 2 to Phase 3 of the Roadmap the test
for a lsquosuccessfulrsquo pilot project will be reflected in developing technology solutions able to attract private
investors willing to commit to their next stage of development either through a demonstration project (Phase
3) or directly to industrial implementation (lsquoearlyrsquo commercial projects)
Phase 3 - Time horizon long term (from year 10-12 to year 15-17)
This phase will focus of the development of ndash one or more ndash demonstration projects to assess the viability of
AP technologies at an industrial scale and facilitating the transfer of AP-based production systems from
demonstration stage into industrial production for lsquofirstrsquo markets The scope of eventual support should focus
on the AP technologies identified as most viable for commercialindustrial application However demonstration
level products should be led by the private sector ndash reflecting the need to assess commercial viability of
technologies ndash with co-funding provided by the public sector ndash reflecting the risk and large financial burden of
investments in such projects
117
Phase 3 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 6)
Recommendation Support for AP demonstrator projects
Objective To develop one or more demonstrator projects to assess the viability of AP technologies at a
close-to industrial scale (ie the project should be of a sufficient size to serve as a platform and
facilitating the transfer of AP-based production systems from demonstration stage into industrial
production for lsquofirstrsquo markets)
Rationale The demonstration project(s) provide a lsquostepping stonersquo between pilot projects and industrial
implementation The projects should not only provide validation of AP devices and systems but
also allow for developing and evaluating the integration of the full AP value chain93
By
demonstration the (commercial) viability of AP the project(s) should promote full industrial
investments that might otherwise be discouraged by the high cost and risk94
At the same time
beyond addressing technological and operational issues the demonstration projects should
address all other aspects ndash eg societalpolitical environmentalsustainability
economiccommercialfinancial legalregulatory geographic etc ndash necessary to evaluate how
AP based production of solar fuels could be implemented in practice
Resources needed To be determined
[Indicative budget envelope circa euro10-20 million per individual project However required funding
will depend on size and ambition of the project and may significantly exceed this amount]
Actors involved Funding sources Industry with EU support
Funding recipients Research and technology development institutions industry
Expected impact The projects should both build investor confidence in the commercial application of AP-based
solar fuel technologies and raise public confidence including in terms of safety and reliability
Priority
Medium
Suggested date of implementation
Long (Phase 3)
Phase 3 - Milestones
Given that the primary purpose of the demonstrator projects is to assess the viability of AP technologies at a
close-to industrial scale an initial milestone for such projects would be for the plants to be operational and to
be able to produce solar fuels in commercially significant volumes Ultimately the target lsquomilestonersquo will be to
produce solar fuels that are cost-competitive under actual market conditions and commercial requirements
while complying with other key requirements (eg safety societal acceptance etc)
622 Supporting and accompanying activities
The technological development of AP will throughout its various phases be guided by regulatory and market
measures as well as the degree of social acceptance In order to help secure favourable conditions for the
development and eventual commercialisation of AP technologies support will need to be provided from a very
early stage onwards within both of these spheres The prices of competing fuels and carbon emissions may
need to be regulated as well as incentives affecting the demand for renewable energy sources introduced
while the breadth of technological development regarding AP should not be hindered by regulation within the
current phase of research nor research into an eventual shift to a lsquohydrogen economyrsquo be put on the back
burner Thorough involvement of all societal actors in education and open debate regarding the potential
benefits and drawbacks of AP technologies as well as barriers to social acceptance and issues raising public
concern is also required At the same time the economic and commercial aspects of AP production
technologies and AP-produced solar fuels need to be understood including in terms of the development of
successful business models and the competitiveness of European industry in the field of AP and renewable
energy more generally
93
Where this covers the whole AP supplyvalue chain from upstream supply (eg materials components etc) to downstream demand (markets)
94 For example high cost resulting from accelerated investments to scale-up to industrial scale and high-risk profile resulting from uncertainty over which AP technologies may prove most successful together with uncertainty over operating costs and future market prices and demand for solar fuels etc These factors may otherwise discourage investments in (initial) full scale projects unless some public support is provided
118
There is potentially a wide range of themes ndash beyond purely technological and operational aspects ndash which
require to be better understood and which may be addressed through supporting and accompanying activities
including the following (non-exhaustive) topics
Industry engagement and technology transfer As far as can be ascertained the engagement of
industry in the field of AP technologies has to date been limited although because of its commercial
sensitivity it is difficult to obtain a clear picture of industrycompaniesrsquo interest in AP Nonetheless there is
a general view that a greater engagement of the industry would be beneficial for the development of AP
technologies and will become increasingly important as technologies reach higher TRLs and move closer
to commercial implementation An active involvement of industrial players in cooperative research projects
could facilitate the transfer of technology from the research community to industry (or vice versa) thereby
helping speed up the evolution from research prototypes and pilots to commercial implementation
Intellectual property protection To ensure future development and industrial application European
intellectual property in the area of AP should be adequately protected through patents At the same time
worldwide developments in AP-related patent-protected technologies should be taken into consideration
to ensure that Europe avoids potentially damaging dependences on non-European technologies
Regulatory conditions and support measures As a minimum AP technologies and products entering
the market should face a legal and regulatory environment that does not discriminate against their use and
provides a level playing field compared to other energyfuel types Beyond this there may be a public
policy justification (eg reflecting positive externalities of AP) for creating a specifically favourable
regulatory and legal framework to encourage the take-up and diffusion of AP technologies and products
At the same time other actions for example AP project financing support may be implemented to support
the industryrsquos AP investments these may be both for production investments but also for downstream
users faced by high switching costs (eg from fossil to solar fuels)
Societal aspects and safety AP technologies may potentially raise a number of public concerns that
need to be understood and addressed These may relate to safety aspects of the production storage
distribution and consumption of AP-based products for example there may be concern over the use of
genetically modified organisms (GMOs) in synthetichybrid AP processes Other areas of concern may
arise for example in relation to land use requirements or use of rare materials etc In general both
among the general public and even within the industry there is limited knowledge of AP Accordingly it
may be appropriatenecessary to implement activities to raise public and industry awareness of AP
Market potential relating to the assessment of the potential role and integration of AP energy supply and
demand Here multiple scenarios are possible for example depending on whether advances in AP
technology are targeted towards production of hydrocarbons or of hydrogen The former would require
fewer changes in terms of supporting infrastructure development (eg for fuel storage and distribution) but
is currently lagging behind in terms of AP technological development For the latter future market potential
will depend on the evolution towards a greater adoption of hydrogen-based fuel technologies Better
understanding of the shape and direction of market developments both within the EU and globally will be
important for assessing which AP technology developments offer the best prospects for future industrial
implementation At the same time the sensitivity of future prospects for AP technologies and products to
developments in the costs and market prices of competing (fossil and renewable) fuels should be
assessed
Industry organisation and business development relating to the assessment of future industrial
organisation of AP-technology production including the full supplyvalue chain for solar fuels (ie from
upstream supply of materials components equipment etc through fuel production to downstream market
supply including storage and distribution) Such an assessment will be required to better understand the
potential position and opportunities for the European industry in the area of AP which should also take
account of the business models and strategies for European players within the market
119
The aforementioned topics illustrate the diversity of the dimensions surrounding AP that require to be better
understood In a first instance more detailed economic legalregulatory social and other analyses of these
topics is warranted In turn this may lead to the formulation of more concrete policies and actions to develop
appropriate regulatory frameworks and to shape other market and business conditions in order to ensure a
supportive environment for the development and implementation of AP technologies and products
121
7 References
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American Chemical Society 2014 136 4316
(2) Tachibana Y Vayssieres L Durrant J R Nature Photonics 2012 6 511
(3) Agency I E 2015
(4) Maeda K Domen K The Journal of Physical Chemistry Letters 2010 1 2655
(5) Ni M Leung M K Leung D Y International Journal of Hydrogen Energy 2008 33 2337
(6) Utschig L M Soltau S R Tiede D M Curr Opin Chem Biol 2015 25 1
(7) Chen L Chen F Xia C Energy amp Environmental Science 2014 7 4018
(8) Carmo M Fritz D L Mergel J Stolten D International Journal of Hydrogen Energy 2013 38 4901
(9) Fukuzumi S Curr Opin Chem Biol 2015 25 18
(10) Pinaud B A Benck J D Seitz L C Forman A J Chen Z Deutsch T G James B D Baum
K N Baum G N Ardo S Energy amp Environmental Science 2013 6 1983
(11) Ursua A Gandia L M Sanchis P Proceedings of the IEEE 2012 100 410
(12) Nelson D L Lehninger A L Cox M M Lehninger principles of biochemistry Macmillan 2008
(13) Alberts B Johnson A Lewis J Raff M Roberts K Walter P Classic textbook now in its 5th
Edition 2010
(14) Magnuson A Anderlund M Johansson O Lindblad P Lomoth R Polivka T Ott S Stensjouml K
Styring S Sundstroumlm V Hammarstroumlm L Accounts of Chemical Research 2009 42 1899
(15) Smolentsev G Sundstroumlm V Coordination Chemistry Reviews 2015 304 117
(16) Hammarstrom L Hammes-Schiffer S Accounts of chemical research 2009 42 1859
(17) Barber J Chemical Society Reviews 2009 38 185
(18) Gust D Moore T A Moore A L Faraday discussions 2012 155 9
(19) Centi G Perathoner S ChemSusChem 2010 3 195
(20) Hansen J Ruedy R Sato M Lo K Reviews of Geophysics 2010 48
(21) Pearson P N Palmer M R Nature 2000 406 695
(22) Faunce T A Lubitz W Rutherford A B MacFarlane D Moore G F Yang P Nocera D G
Moore T A Gregory D H Fukuzumi S Energy amp Environmental Science 2013 6 695
(23) Gorka M Schartner J van der Est A Rogner M Golbeck J H Biochemistry 2014 53 2295
(24) Gust D Moore T A Moore A L Accounts of chemical research 2009 42 1890
(25) Armaroli N Balzani V Angew Chem Int Ed Engl 2007 46 52
(26) House R L Iha N Y M Coppo R L Alibabaei L Sherman B D Kang P Brennaman M K
Hoertz P G Meyer T J Journal of Photochemistry and Photobiology C Photochemistry Reviews 2015 25 32
(27) Utschig L M Silver S C Mulfort K L Tiede D M Journal of the American Chemical Society 2011
133 16334
(28) Listorti A Durrant J Barber J Nature materials 2009 8 929
(29) Styring S Faraday discussions 2012 155 357
(30) Walter M G Warren E L McKone J R Boettcher S W Mi Q Santori E A Lewis N S
Chemical reviews 2010 110 6446
(31) Lewis N S Science 2016 351 aad1920
(32) Concepcion J J House R L Papanikolas J M Meyer T J Proceedings of the National Academy
of Sciences 2012 109 15560
(33) Barber J Tran P D Journal of The Royal Society Interface 2013 10 20120984
(34) Gersten S W Samuels G J Meyer T J Journal of the American Chemical Society 1982 104
4029
(35) Gust D Moore T A Moore A L Accounts of Chemical Research 2001 34 40
(36) Kalyanasundaram K Graetzel M Current opinion in Biotechnology 2010 21 298
(37) Wen F Li C Accounts of chemical research 2013 46 2355
(38) McCrory C C Jung S Ferrer I M Chatman S M Peters J C Jaramillo T F Journal of the
American Chemical Society 2015 137 4347
(39) Alenazey F Alyousef Y Almisned O Almutairi G Ghouse M Montinaro D Ghigliazza F
International Journal of Hydrogen Energy 2015 40 10274
(40) Asthana S Samanta C Bhaumik A Banerjee B Voolapalli R K Saha B Journal of Catalysis
2016 334 89
(41) Ihara M Nishihara H Yoon K S Lenz O Friedrich B Nakamoto H Kojima K Honma D
Kamachi T Okura I Photochemistry and photobiology 2006 82 676
122
(42) Ihara M Nakamoto H Kamachi T Okura I Maedal M Photochemistry and photobiology 2006 82
1677
(43) Fukuzumi S Yamada Y Suenobu T Ohkubo K Kotani H Energy amp Environmental Science 2011
4 2754
(44) Vignais P M Billoud B Meyer J FEMS microbiology reviews 2001 25 455
(45) Utschig L M Dimitrijevic N M Poluektov O G Chemerisov S D Mulfort K L Tiede D M The
Journal of Physical Chemistry Letters 2011 2 236
(46) Prince R C Kheshgi H S Critical reviews in microbiology 2005 31 19
(47) Brown K A Wilker M B Boehm M Dukovic G King P W Journal of the American Chemical
Society 2012 134 5627
(48) Lubner C E Applegate A M Knoumlrzer P Ganago A Bryant D A Happe T Golbeck J H
Proceedings of the National Academy of Sciences 2011 108 20988
(49) Iwuchukwu I J Vaughn M Myers N ONeill H Frymier P Bruce B D Nature nanotechnology
2010 5 73
(50) Yacoby I Pochekailov S Toporik H Ghirardi M L King P W Zhang S Proceedings of the
National Academy of Sciences 2011 108 9396
(51) Silver S C Niklas J Du P Poluektov O G Tiede D M Utschig L M Journal of the American
Chemical Society 2013 135 13246
(52) Grimme R A Lubner C E Bryant D A Golbeck J H Journal of the American Chemical Society
2008 130 6308
(53) Rumpel S Siebel J F Faregraves C Duan J Reijerse E Happe T Lubitz W Winkler M Energy amp
Environmental Science 2014 7 3296
(54) Volgusheva A Styring S Mamedov F Proceedings of the National Academy of Sciences 2013 110
7223
(55) Rozendal R A Jeremiasse A W Hamelers H V Buisman C J Environmental Science amp
Technology 2007 42 629
(56) Clauwaert P Toledo R Ha D v d Crab R Verstraete W Hu H Udert K Rabaey K Water
Science and Technology 2008 57 575
(57) Bajracharya S ter Heijne A Benetton X D Vanbroekhoven K Buisman C J Strik D P Pant
D Bioresource technology 2015 195 14
(58) Li M Canniffe D P Jackson P J Davison P A FitzGerald S Dickman M J Burgess J G
Hunter C N Huang W E The ISME journal 2012 6 875
(59) Zhang D Zhao Y He Y Wang Y Zhao Y Zheng Y Wei X Zhang L Li Y Jin T ACS
synthetic biology 2012 1 274
(60) Blankenship R E Tiede D M Barber J Brudvig G W Fleming G Ghirardi M Gunner M
Junge W Kramer D M Melis A science 2011 332 805
(61) Fujishima A Honda K Nature 1972 238 37
(62) James B D Baum G N Perez J Baum K N Square O V DOE report 2009
(63) Hanna M Nozik A Journal of Applied Physics 2006 100 074510
(64) Ross R T Hsiao T L Journal of Applied Physics 1977 48 4783
(65) Khaselev O Turner J A Science 1998 280 425
(66) Wang X Maeda K Chen X Takanabe K Domen K Hou Y Fu X Antonietti M Journal of the
American Chemical Society 2009 131 1680
(67) Kanan M W Nocera D G Science 2008 321 1072
(68) Brillet J Yum J-H Cornuz M Hisatomi T Solarska R Augustynski J Graetzel M Sivula K
Nature Photonics 2012 6 824
(69) Kim J H Kaneko H Minegishi T Kubota J Domen K Lee J S ChemSusChem 2016 9 61
(70) Gao L Cui Y Wang J Cavalli A Standing A Vu T T Verheijen M A Haverkort J E
Bakkers E P Notten P H Nano letters 2014 14 3715
(71) Standing A Assali S Gao L Verheijen M A van Dam D Cui Y Notten P H Haverkort J E
Bakkers E P Nature communications 2015 6
(72) Gao L Cui Y Vervuurt R H van Dam D van Veldhoven R P Hofmann J P Bol A A
Haverkort J E Notten P H Bakkers E P Advanced Functional Materials 2015
(73) Smolyakov G A Osinski M A Google Patents 2011
(74) Herrera A S Google Patents 2013
(75) Joo O S Jung K D Min B K Kim S H Oh J W Google Patents 2008
(76) Google Patents 2015
(77) Liu J Zhang Y Lu L Wu G Chen W Chemical Communications 2012 48 8826
(78) Li J Wu N Catalysis Science amp Technology 2015 5 1360
(79) Laguna-Bercero M A Journal of Power Sources 2012 203 4
123
(80) Graves C Ebbesen S D Mogensen M Solid State Ionics 2011 192 398
(81) Li W Wang H Shi Y Cai N International journal of hydrogen energy 2013 38 11104
(82) Fu Q Mabilat C Zahid M Brisse A Gautier L Energy amp Environmental Science 2010 3 1382
(83) Graves C Ebbesen S D Mogensen M Lackner K S Renewable and Sustainable Energy Reviews
2011 15 1
(84) Christopher K Dimitrios R Energy amp Environmental Science 2012 5 6640
(85) Sun X Chen M Jensen S H Ebbesen S D Graves C Mogensen M international journal of
hydrogen energy 2012 37 17101
(86) Ivy J Summary of electrolytic hydrogen production milestone completion report National Renewable
Energy Lab Golden CO (US) 2004
(87) Haering C Roosen A Schichl H Schnoumlller M Solid State Ionics 2005 176 261
(88) Mahmood A Bano S Yu J H Lee K-H Energy 2015 90 Part 1 344
(89) Jakobsson N B FRIIS P C BOslashGILD H J Google Patents 2014
(90) Stoots C M OBrien J E Herring J S Lessing P A Hawkes G L Hartvigsen J J Google
Patents 2011
(91) JABBAR M HOslashGH J Stamate E BONANOS N Google Patents 2013
[Ca
talo
gu
e n
um
be
r]
KI-N
A-2
7-9
87-E
N-N
KI-N
A-2
7-9
87-E
N-N
7
Executive Summary
Objectives and methodology
Artificial photosynthesis (AP) is considered among the most promising new technologies able to deliver
sustainable alternatives to current fuel supplies often viewed as a potential ldquogame changerrdquo in the fields of
energy conversion and energy production AP can be used to produce hydrogen or carbon-based fuels ndash
collectively referred to as ldquosolar fuelsrdquo ndash that offer an efficient and transportable store of (solar) energy which
can be used as an alternative to fossil fuels and as a feedstock for a wide range of industrial processes
Set against the above background the purpose of this study is to provide a full assessment of the situation of
AP providing answers to the questions Who are the main European and global actors in the field What is
the ldquostate of the artrdquo and what are the main ldquobottlenecksrdquo in scientific and technological development What
are the key economic and technological parameters to accelerate industrial implementation Answers to the
questions provide in turn the basis for formulating recommendations on the pathways to follow and the action
to take to maximise the eventual market penetration and exploitation of AP technologies
To gather information on the direction capacities and challenges of ongoing AP development activities the
study has conducted a comprehensive review of scientific and other literature and implemented a survey of
academics and industrial players This information together with the findings from a series of in-depth
interviews provides the basis for a multi-criteria analysis to identify key bottlenecks for the main AP
technology pathways The study findings were validated at a participatory workshop of leading European AP
researchers which also identified scenarios and sketched out roadmaps for actions to support the future
development of AP technologies over the short to long term
Definition of Artificial Photosynthesis
For the purposes of this study artificial photosynthesis is understood to be a process that aims to mimic
the physical chemistry of natural photosynthesis by absorbing solar energy in the form of photons and
using this energy to generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
Main technology pathways for artificial photosynthesis
It is difficult to precisely define the parameters of AP but there are three main identifiable technology pathways
along which research and development is now advancing
Synthetic biology amp hybrid systems aim to mimic existing biological systems that perform different stages of
photosynthesis (ie light-harvesting charge separation or molecule synthesis) and combine them to produce
specific fuel molecules These technologies are at a very early stage (TRL 1-4) however researchers have
already produced small quantities of hydrogen through the water-splitting reaction and have demonstrated the
reduction of carbon dioxide to methane and acetate Research is also investigating the possibility of using
basic cells (biological) to host biological machinery to generate more complex fuel molecules The long-term
goal is to reliably generate large quantities of fuel molecules combining and converting simple starting
compounds such as H2 and CO2 into a series of different compounds using enzymes and synthetic organic
and inorganic catalysts
8
Photoelectrocatalysis combines and integrates photovoltaic (PV) technologies ndash ie semiconductor materials
able to generate electric current from sunlight ndash with water electrolysis in a photoelectrochemical cell (PEC) or
suspensions of photoactive nanoparticles thereby enabling solar energy to be used to produce hydrogen (and
oxygen) via a water-splitting reaction PV technologies are already deployed commercially and are producing
power on a megawatt scale (TRL 7-8) however PECs to perform photoelectrocatalysis are as yet at a
relatively low stage of development (TRL 2-4) The main challenges facing this technology involve developing
materials that have high solar-to-hydrogen (STH) efficiencies are cheap to manufacture (eg use earth-
abundant metals) and are stable for long periods of time
Co-electrolysis uses co-electrolysis of carbon dioxide and water to generate syngas (COH2) by
simultaneously reducing carbon dioxide and water using a high temperature solid oxide cell electrolyser
(SOEC) syngas can then be used to generate simple intermediate compounds that can be used as feedstock
for more complicated chemicals Water electrolysers ndash such as alkaline and polymer electrolyte membrane
(PEM) electrolysers ndash used to convert water into H2 and O2 are mature technologies (TRL 7-8) that have
been commercialised SOECs are at a lower level of development (TRL 3-5) and given their high electricity
requirements current research is focused on increasing their efficiency
Technology pathways for artificial photosynthesis and indicative selection of generated compounds
Source University of Sheffield (PV = Photovoltaics)
AP research in Europe
Research in the AP field ndash bringing together interdisciplinary expertise from biology biochemistry biophysics
and physical chemistry ndash has intensified over the last decade Today more than 150 research groups are
estimated to be active worldwide of which 60 are in Europe1 Interest from industry is growing as well
although it remains limited due to the overall low levels of readiness for commercial application of many AP
technologies
Europe has a diverse community of researchers active in the AP field and covering all the main pathways with
the largest numbers of research groups located in Germany the Netherlands Sweden and the UK The most
significant and only truly pan-European-level research network is AMPEA2 but most networks and consortia
are national Some Member States have set up their own AP research programmes roadmaps and funds and
1 Source study estimates
2 Advance Materials and Processes for Energy Application (AMPEA) which is one of the joint programmes of the Europe nargy Research
alliance (EERA)
9
there has been successful collaboration in several ongoing European-funded FP7 projects Overall however
the level of funding in Europe falls short of that available elsewhere and national research plans (and funding)
seem fragmented and scattered with a short-term focus and lacking an integrated approach with common
research goals and objectives Equally the level of collaboration between academia and industry seems to be
more limited in Europe compared for example to the US or Japan
Relatively few companies are active in the field of AP and they can be counted in the lsquotensrsquo rather than
lsquohundredsrsquo Co-electrolysis is the only area where AP-related technologies are currently commercially viable
while current industry research activities mostly concern photoelectrocatalysis where companies from various
sectors (eg ranging from automotive and electronics to chemicals and oil refining) are involved There is
some industry involvement in synthetic biology amp hybrid systems but it is limited reflecting the early stage of
research activities along this pathway
Main challenges to development and implementation of AP technologies
To form a sustainable and cost-effective part of future European and global energy systems and a source of
high-value and low carbon feedstock chemicals the development of AP technologies must address certain
fundamental requirements
Efficiency in each main step of AP light captureharvesting (eg maximising the percentage of the
spectrum that can be utilised) energy transfer to a reaction centre (eg minimising energy loss during the
transfer) and charge generation and separation to allow the desired chemical reaction to take place (eg
preventing charge recombination)
Durability of the system in terms of the amount of energy that can be produced during the lifetime of an AP
system which is a challenge because of the rapid degradation of some materials under AP system
conditions (eg lack of long-term stability in aqueous conditions or when exposed to sunlight)
Sustainability of material use eg minimising the use of rare and expensive raw materials
To meet these requirements the main AP technology pathways must overcome several gaps in fundamental
knowledge and technology development (see tables) Even if these gaps can be addressed and the feasibility
of commercial- and industrial-scale deployment of AP systems can be demonstrated at a cost level that
enables AP-based products to be competitive in the market place commercial implementation may raise other
practical concerns These may arise in relation to land use water availability and possible environmental or
social concerns which have not yet been fully explored
Synthetic biology amp hybrid systems
Knowledge gaps Technology gaps
Develop molecular and synthetic biology tools to enable
the engineering of efficient metabolic processes within
microorganisms
Improve metabolic and genetic engineering of
microorganism strains
Improve metabolic engineering of strains to facilitate the
production of a large variety of chemicals polymers and
fuels
Enhance (product) inhibitor tolerance of strains
Minimise losses due to chemical side reactions (ie
competing pathways)
Develop efficient mechanisms and systems to separate
collect and purify products
Improve stability of proteins and enzymes and reduce
degradation
Develop biocompatible catalyst systems not toxic to
micro-organisms
Optimise operating conditions and improve operation
stability (from present about gt100 hours)
Mitigate bio-toxicity and enhance inhibitor tolerance at
systems level
Improve product separation at systems level
Improve photobioreactor designs and up-scaling of
photobioreactors
Integrate enzymes into the hydrogen evolving part of
ldquobionic leafrdquo devices
Improve ldquobionic leafrdquo device designs
Up-scale ldquobionic leafrdquo devices
Improve light energy conversion efficiency (to gt10)
Reduce costs of the production of formic acids and other
chemicals polymers and fuels
10
Photoelectrocatalysis
Knowledge gaps Technology gaps
Increase absorber efficiencies
Increase understanding of surface chemistry at
electrolyte-absorber interfaces incl charge transfer
dynamics at SCdyecatalyst interfaces
Develop novel sensitizer assemblies with long-lived
charge-separated states to enhance quantum
efficiencies
Improve charge transfer from solid to liquid
Increase stability of catalysts in aqueous solutions
develop self-repair catalysts
Develop catalysts with low over-potentials
Reduce required rare and expensive catalysts by core-
shell catalyst nanoparticles with a core of an earth-
abundant material
Develop novel water-oxidation catalysts eg based on
cobalt- and iron oxyhydroxide-based materials
Develop efficient tandem absorber structures on (widely
available and cheaper) Si substrates
Develop nanostructure configurations promising
advantages with respect to materials use optoelectronic
properties and enhanced reactive surface area
Reduce charge carrier losses at interfaces
Reduce catalyst and substrate material costs
Reduce costs for tandem absorbers using silicon-based
structures
Develop concentrator configurations for III-V based
tandem absorber structures
Scale up deposition techniques and device design and
engineering
Improve device stability towards long-term stability goal
of gt1000 hours
Improve the STH production efficiencies (to gt10 for
low-cost material devices)
Reduce costs towards a hydrogen production price of 4
US$ per kg
Co-electrolysis
Knowledge gaps Technology gaps
Basic understanding of reaction mechanisms in co-
electrolysis of H2O (steam) and CO2
Basic understanding of the dynamics of
adsorptiondesorption of gases on electrodes and gas
transfer during co-electrolysis
Basic understanding of material compositions
microstructure and operational conditions
Develop new improved materials for electrolytes and
electrodes
Avoid mechanical damages (eg delamination of
oxygen electrode) at electrolyte-electrode interface
Reduce carbon (C) formation during co-electrolysis
Optimise operation temperature initial fuel composition
and operational voltage to adjust H2CO ratio of the
syngas
Replace metallic based electrodes by pure oxides
Improve long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O
(steam) and CO2
Improved stability performance (from present ~50 hours
towards the long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel
composition and operational voltage to adjust H2CO
ratio of the syngas
Improvement of co-electrolysis syngas production
efficiencies towards values facilitating the production of
competitive synthetic fuels via FT-processes
Cost reduction towards competitiveness of synthetic
fuels with fossil fuels
The AP technology development roadmap
Although AP technologies show great potential and despite significant progress made in recent years there is
still a significant way to go before they are ready for industrial implementation Although some aspects of AP-
based systems are well developed the assessment of the existing lsquostate of the artrsquo shows that AP
technologies are generally at low levels of technology readiness (eg TRL 3-4) Moreover there is not yet
compelling evidence to suggest any AP pathway (or sub-approach therein) is ldquomore promisingrdquo than another
This being the case it seems appropriate to adopt an ldquoopenrdquo approach to possible support measures for AP-
related research efforts in the near term which does not single out and prioritise any specific AP pathway or
approach
Nonetheless if AP technologies are to fulfil their potential it will be necessary to achieve the transition from
fundamental research- and laboratory-based validation to demonstration at commercial of near-commercial
scales this ambition forms the long-term goal for the proposed AP technology development roadmap
11
The roadmap distinguishes 3 phases (see figure below) and corresponding recommendations for specific
actions
Phase 1 (short term) Early stage research and scaling-up to pilot projects
Action 1 Support for multiple small AP research projects to address existing knowledge and technology gaps and to
promote long-term advances in scientific knowledge that may contribute to breakthroughs in novel
approaches for AP and to address technology challenges across the board of current (and potential) AP
pathways and approaches
Action 2 Support for enhanced networking of AP research and technology development to reduce fragmentation and
promote coordination and cooperation of research efforts in the AP and related fields through the support for
pan-European networking activities and promotion of research synergies
Action 3 Inducement prize to provide additional stimulus for research technology development and innovation
through a (financial) prize targeting ldquoproof of conceptrdquo of significant advances in the AP field
Phase 2 (medium term) Pilot project implementation and scaling-up to demonstrator projects
Action 4 Support for AP pilot projects to demonstrate the viability of AP concepts through support for a (limited)
number of pilot plant scale projects of the ldquomost promisingrdquo AP technologies
Action 5 Support for AP coordination to ensure effective use of research budgets and to avoid duplication of research
efforts Moving to a common European AP technology strategy requires inter alia alignment of national
research efforts and cooperation at a broader international level Equally to accelerate industrial
implementation cooperation and coordination of activities among the lsquoresearch communityrsquo and industry
should be promoted
Phase 3 (long term) Demonstrator project implementation
Action 6 Support for AP demonstrator projects to demonstrate the viability of AP technologies through support for one
or more demonstrator projects that facilitate the transfer of AP production systems to industrial production for
ldquofirstrdquo markets while allowing an evaluation of the development and integration of the full AP value chain (ie
from upstream supply of materials and components to downstream markets for AP-based products) The
demonstrator project(s) should also address other aspects (eg societal political environmental economic
and regulatory) necessary to evaluate the practical implementation of AP technologies
NB For convenience the timeline of these actions is presented in 3 distinct phases Some AP technologies are however
more advanced than others and could already be at or close to readiness for pilot projects Conversely certain fundamental
knowledge and technology issues cannot expect to be resolved in the short term Accordingly the different phases as
proposed within the roadmap should not be considered to define a strictly chronological sequencetiming of actions
12
Visualisation of the AP technology development roadmap with illustrative project examples
Source Ecorys
Phase 1 Phase 3Phase 2
TRL 9 Industrial Implementation
TRL 6-8 Demonstrator
TRL 3-6 Pilot Projects
TRL 1-3 Fundamental
2017 2025 2035
Example projects- Research on metabolic and genetic engineering of strains for photosynthetic microbial cell factories
- Research on strains for the production of a variety of chemicals polymers and fuels
- Research on the understanding of surface chemistry at electrolyte-absorber interface in PEC
- Development of novel water-oxidation catalysts for direct water splitting
- Research on improvements of light absorption and carrier separation efficiency in PEC devices
- Research on new materials for electrodes and electrolytes in electrolysis cells
-Research to improve the basic understanding of reaction mechanisms in co-electrolysis (dynamics of adsorptiondesorption of gases gas transfer degradation mechanisms etc)
Example of projects - Improvements of operating stability of microbial cell factories
- Improvements of bionic leaf device design
- Study on long-term durability of molecular components used in DS-PEC devices development of active photosensitizer and catalyst
- Improvement of device stability and STH production efficiencies for direct water-splitting devices at pilot plant scale
- Support the development of lab-scale modules and demonstration facilities of electrolysis cells for CO2 valorisation
- Support the upscaling of cells for efficient co-electrolysis of H2O (steam) and CO2 in Solid Oxide Electrolysis Cells (SOEC)
- Development at a near-commercial scale of demonstrator plant(s) for co-electrolysis
Example of projects- Pilot plant scale of photobioreactors for photosynthetic microbial cell factories
- Pilot plant scale of ldquobionic leafrdquo devices
- Development at a near-commercial scale of demonstrator plant(s) for direct water-splitting devices based on several absorber materials (eg dye-sensitised photo-electrochemical cell (DS-PEC) device silicon-based tandem absorber structures)
13
Supporting activities
Looking beyond the technological and operational aspects of the roadmap the study finds several areas
where actions may be taken to provide a better understanding of the AP field and to accelerate development
and industrial implementation namely
Networking and coordination of research With the exception of the few pan-European initiatives (eg AMPEA
and FP7 projects) the degree of collaboration among research groups is low Networking and coordination
activities (for example through Horizon 2020 Coordination amp Support Action - CSA) would contribute to reduce
duplication of efforts and facilitate exchange among researchers
Industry engagement and technology transfer Engagement of industry in development activities which has so
far been relatively limited will become increasingly important as AP technologies move to higher levels of
readiness for commercial implementation Encouraging active involvement of industrial players in research
projects could ease the transfer of technology from the research community to industry (or vice versa) thereby
helping expedite the evolution from prototypes and pilots to marketable products
Public policy and regulatory conditions To encourage industrial implementation and market penetration AP
technologies and products should face a legal and regulatory environment that offers a ldquolevel playing fieldrdquo
compared to other energyfuel types Beyond this reflecting the sustainability and environmental
characteristics of AP there may be a public policy justification for creating a regulatory and legal framework
and possibly other measures to specifically encourage the adoption and diffusion of AP technologies and
products
Safety concerns and societal acceptance AP technologies could potentially raise a number of public
concerns for example the safety aspects of the production storage distribution and consumption of AP-
based products the use of GMOs in synthetichybrid AP processes the use of rare expensive andor toxic
materials extensive land use requirements etc Such legitimate public concerns need to be identified
understood and properly addressed if AP is to overcome barriers to widespread societal acceptance These
aspects should be an integral part of an overall AP research agenda that provides for open dialogue even
from very early stages of technological development and identifies potential solutions and mitigating
measures
Protection of Intellectual Property To become a successful leading player in the development and industrial
application of AP technologies researchers and industry must be able to adequately protect their intellectual
(industrial) property rights (eg patent protection) without this becoming a barrier to overall technology
development and implementation It will be important to both protect European intellectual property rights
while also follow global developments in AP-related patent-protected technologies thereby ensuring that
Europe has a secure strategic position in the AP field and avoiding potentially damaging dependencies on
non-European technologies
15
Table of contents
Abstract 5
Executive Summary 7
Table of contents 15
1 Introduction 21
2 Scope of the study 23
21 Overview of natural photosynthesis 23
22 Current energy usage and definition of artificial photosynthesis 25
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the study29
231 Synthetic biology amp hybrid systems 31
232 Photoelectrocatalysis of water (water splitting) 31
233 Co-electrolysis 31
3 Assessment of the technological development current status and future perspective 33
31 Synthetic biology amp hybrid systems 34
311 Description of the process 34
312 Current status review of the state of the art 35
313 Future development main challenges 38
32 Photoelectrocatalysis of water (water splitting) 39
321 Description of the process 39
322 Current status review of the state of the art 41
323 Patents 44
324 Future development main challenges 45
33 Co-electrolysis 47
331 Description of the process 47
332 Current status review of the state of the art 52
333 Patents 53
334 Future development main challenges 54
34 Summary 54
4 Mapping research actors 57
41 Main academic actors in Europe 57
411 Main research networkscommunities 57
412 Main research groups (with link to network if any) 59
42 Main academic actors outside Europe 62
421 Main research networkscommunities 62
422 Main research groups (with link to network if any) 64
43 Level of investment 66
431 Research investments in Europe 67
432 Research investments outside Europe 71
44 Strengths and weaknesses 73
441 Strengths and weaknesses of AP research in general 73
442 Strengths and weaknesses of AP research in Europe 74
16
45 Main industrial actors active in AP field 76
451 Industrial context 76
452 Main industrial companies involved in AP 76
453 Companies active in synthetic biology amp hybrid systems 77
454 Companies active in photoelectrocatalysis 79
455 Companies active in co-electrolysis 82
456 Companies active in carbon capture and utilisation 83
457 Assessment of the capabilities of the industry to develop AP technologies 85
46 Summary of results and main observations 86
5 Factors limiting the development of AP technology 91
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges 91
52 Current TRL and future prospects of investigated AP RTD initiatives 95
53 Knowledge and technology gaps of investigated AP RTD initiatives 95
54 Coordination of European research 100
55 Industry involvement and industry gaps 101
56 Technology transfer opportunities 104
57 Regulatory conditions and societal acceptance 107
6 Development roadmap 109
61 Context 109
611 General situation and conditions for the development of AP 109
612 Situation of the European AP research and technology base 110
62 Roadmap overview 111
621 Knowledge and technology development 111
622 Supporting and accompanying activities 117
7 References 121
17
List of figures
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton
gradient NADPH and ATP 24
Figure 22 Worldwide consumption of fuel types by percentage 27
Figure 31 General development and supply chain 33 Figure 32 Diagrammatic representation of a PSI-platinum hybrid system 34
Figure 34 Photoelectrochemical cell capable of water oxidation using solar energy 40
Figure 35 PEC reactor types 42
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting
photoelectrochemical cells 47 Figure 37 Schematic diagram of water electrolysis being conducted in an alkaline electrolyser 48
Figure 38 Schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell 49
Figure 41 Research groups in Artificial Photosynthesis in Europe 62
Figure 42 Research groups active in the field of AP globally 66
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020 69
Figure 44 Hondarsquos sunlight-to-hydrogen station 80
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels 85
Figure 61 General development roadmap visualisation 112
19
List of tables
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
36
Table 01 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the
performance data for each device This table was originally constructed by Ursua et al 201211
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis
cell electrolysers This table was originally constructed by Carmo et al 20138 53
Table 41 Number of research groups and research institutions in European countries 59
Table 42 Number of research groups per research area (technology pathway) 60
Table 43 Number of research groups and research institutions in non-European countries 64
Table 44 Number of research groups per research area (technology pathway) 65
Table 45 Investments in the field of artificial photosynthesis 66
Table 46 EU FP6 and FP7 projects on artificial photosynthesis 68
Table 47 Total EU budget on artificial photosynthesis per technology pathway 68
Table 48 Summary of strengths and weaknesses of research globally 73
Table 49 Summary of strengths and weaknesses of research in Europe 75
Table 410 Overview of the size of the industrial community number of companies per pathway 77
Table 411 Organisations in synthetic biology amp hybrid systems 78
Table 412 Organisations in the field of photoelectrocatalysis 79
Table 413 Companies in co-electrolysis 82
Table 414 Organisations active in carbon capture and utilisation 83
Table 415 Summary of findings size of research community 87
Table 416 Summary of findings size of industrial community 89
21
1 Introduction
To establish a world-class technology and innovation sector that is fit to cope with the challenges up to 2020
and beyond the European Commission initiated an update of its EU energy research and innovation (RampI)
policy leading to the publication of the Communication ldquoTowards an Integrated Strategic Energy Technology
(SET) Plan Accelerating the European Energy System Transformation (C (2015) 6317 final) in September
2015 Under the heading ldquoKeeping Technology Actions Openrdquo the SET Plan Integrated Roadmap states that
ldquothe emergence of new technologies required for the overall transition of the energy sector towards
decarbonisation requires breakthroughs which have to be based on fundamental and generic knowledge at
the international state of artrdquo Artificial Photosynthesis counts among the most promising new technologies and
is often considered as a potential ldquogame changerrdquo technology in the fields of energy conversion and energy
production
The study ldquoAssessment of artificial photosynthesisrdquo has been implemented in the first semester of 2016
against this background the study aims to support future policy developments in the area in particular in the
design of public interventions allowing to fully benefit from the potential offered by the technologies The study
has three specific objectives The first objective is to provide a detailed review of the state of the art of artificial
photosynthesis technologies as well as an inventory of research players from the public and private sector
The second objective is to analyse the factors and parameters influencing the future development of these
technologies The third objective is to provide recommendations for public support measures aimed at
maximising this potential
The structure of the report is as follows Section 2 describes the scope of the study with a review of the
different types of Artificial Photosynthesis Section 3 provides an assessment of the technological
development based on a review of the literature Section 4 maps the main academic and industrial actors
Section 5 analyses the factors limiting the development of Artificial Photosynthesis technologies and a
development roadmap is presented in the Section 6
23
2 Scope of the study
21 Overview of natural photosynthesis
Photosynthetic and heterotrophic organisms exist together in a steady state in the biosphere Photosynthetic
organisms capture solar energy in the form of photons this captured energy is used to produce chemical
energy that the organism uses to form adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide
phosphate (NADPH) ATP and NADPH are then used to generate organic compounds such as carbohydrates
from water and carbon dioxide12
Photosynthesis can be broken down into two processes light-dependant
reactions and carbon-assimilation reactions where the latter are driven by the products of the light reactions
In the light reactions electrons are obtained from water molecules that have been oxidised in a process often
referred to as ldquowater splittingrdquo to form electrons (e-) hydrogen ions (H
+) and molecular oxygen (O2) The
electrons are driven through a series of membrane-bound carrier proteins including cytochromes iron-sulphur
proteins and quinones to produce a proton gradient which is used to generate ATP and NADPH this is
summarised in Figure 21 The carbon-assimilation reactions use NADPH ATP electrons and H+ to reduce
carbon dioxide in a series of enzymatic reactions to generate an array of compounds21213
The light-dependent and carbon assimilation reactions of photosynthesis take place in the chloroplasts of
eukaryotic cells Chloroplasts are intracellular organelles with a non-uniform shape similar to that of
mitochondria They both have inner and outer membranes that enclose an inner compartment which is
permeable to small molecules and ions respectively The thylakoid membrane contains the photosynthetic
pigments and enzyme complexes that carry out the light reactions and ATP synthesis and are on the inside of
the inner membrane Chlorophylls are present in the thylakoid membrane and are responsible for absorbing
solar energy in plants An array of chlorophylls is called a photosystem Chlorophylls are green pigments
consisting of long phytol chains with a polycyclic planar structure similar to the protoporphyr in haemoglobin
at the top of the molecule However instead of a Fe2+
at the centre there is a Mg2+
coordinated by four
nitrogen atoms The phytol chain is esterified to a carboxyl group in ring IV The groups on the edge of the ring
(=CH2 and -CH3) can be exchanged for other groups depending on the organism the chlorophyll is present in
The heterocyclic five-ring system that surrounds Mg2+
has an extended polyene structure with alternating
single and double bonds These compounds strongly absorb in the visible region and have high extinction
coefficients Plants always contain chlorophyll α and chlorophyll β which both absorb green light at slightly
different wavelengths this maximises the amount of light the organism can utilise Chlorophylls bind with
specific proteins and membranes to form light-harvesting complexes (LHCs) In addition to chlorophylls which
are the main pigments in plants there are accessory pigments called carotenoids that absorb photons that
have different wavelengths so more of the spectrum can be utilised When a photon is absorbed by a
chlorophyll an electron in the chromophore portion is raised to a higher energy state called the excited state
When the electron moves back down to its ground state it can release the energy as light or heat In
photosynthesis instead of the energy being released as light or heat it is transferred from the excited
chromophore to a neighbouring chromophore in a process called ldquoexcitation transferrdquo1213
All of the pigment molecules in a photosystem can absorb photons and transfer the energy to other pigments
but only a number of pigments are associated with the photochemical reaction centre (PRC) The excitation
energy can be passed through multiple pigment molecules until it reaches a pigment associated with the PRC
The PRC transduces the excitation energy into chemical energy by passing the excitation energy to a nearby
molecule acting as an electron acceptor This leaves the chlorophyll with a positive charge which is
neutralised by another electron donor the electron acceptor becomes negatively charged In this way
excitation caused by photon absorption causes electric charge separation and starts the oxidation-reduction
chain Light-driven electron transfer in chloroplasts during photosynthesis is carried out by a number of multi-
enzyme complexes in the thylakoid membrane1213
24
Photosynthetic bacteria usually have one or two reaction centres Purple bacteria pass electrons through a
pheophytin which is a chlorophyll without the Mg2+
at the centre of the ring to a quinone Green sulphur
bacteria pass electrons through a quinone to an iron-sulphur centre The photosynthetic machinery in purple
bacteria is made up of 3 basic units a single reaction centre (P870) a cytochrome bc1 electron-transfer
complex (similar to complex III found in mitochondria) and an APT synthase Absorption of a photon drives
electrons through pheophytin and a quinone to the cytochrome bc1 complex following which electrons pass
through this complex to the cytochrome bc1 complex and back to the reaction centre This movement of
electrons generates the energy needed by the cytochrome bc1 complex to pump protons across the
membrane and create the gradient that generates ATP1213
The photosynthetic apparatus of cyanobacteria and plants is more complex than that found in a one-system
bacterium due to them containing two photosystems in the thylakoid membrane Photosystem II acts like the
single photosystem found in purple bacteria It should be noted that the water-splitting reaction occurs at
PSII14
When the reaction centre of photosystem II (P680) is excited electrons are driven through the
cytochrome b6f complex which pumps hydrogen ions across the thylakoid membrane to generate a proton
gradient PSI aids in the reduction of NADP+ to NADPH by absorbing a photon at 700 nm to excite an
electron which is passed through a number of carrier molecules to plastoquinone and then to ferredoxin-
NAPD+ reductase which generates NADPH As previously discussed the proton gradient that has been
generated from transferring the electrons that were excited by the photons is used by ATP synthase to
generate ATP To summarise the light-dependent reactions cause water to split into oxygen electrons and
protons which are used to generate a proton gradient form NAPDH from NAPD+ and generate ATP The
main differences between the two photosystems are the wavelengths of light they absorb and that PSII
conducts water oxidation (while PSI does not) Both absorb photons and both are capable of generating
ATP12-16
In the carbon-assimilation reactions ATP and NADPH are used to reduce (gain electrons) carbon
dioxide to form phosphates starch and sugars as part of the Calvin cycle which takes place in the stroma
this process is also known as carbon fixation1213
Figure 21 Schematic diagram of electron flow in in vivo photosynthesis that is used to generate a proton gradient NADPH and ATP
Theoretically the efficiency of natural photosynthetic systems should be around 26 This is calculated by
knowing the energy content of a glucose molecule is 672 kcal mol-1
To generate a glucose molecule 48
photons with a wavelength of 680 nm are needed which together have an energy of 42 kcal per quantum
mole which is equal to 172 kcal mol-1
672 kcal mol-1
divided by 172 kcal mol-1
makes for 26 efficiency
However in reality an efficiency of less than 2 is usually achieved in optimal conditions17
The efficiency of
natural photosynthetic systems is limited by electron-hole recombination which is when the charge separation
25
process is not successful Even when this process is successful up to half of the energy from the excited state
of the chlorophyll is used2 Energy is also used by the organism to ensure other processes within the cell are
functioning The inefficiencies of natural photosynthesis highlight major areas where researchers are looking
to improve in artificial photosynthetic systems and are discussed over the next sections
Photodamage occurs in photosynthetic systems when solar energy cannot be effectively dissipated as heat or
be used to form photosynthetic products fast enough Upon photon absorption chlorophylls are excited to a
singlet state whereby under normal conditions the chlorophyll molecule will either pass the energy to another
chlorophyll molecule by FRET emit a photon or dissipate the energy as heat High levels of light increase the
amount of photosynthesis occurring as well as the amount of time chlorophylls spend in their singlet state
which increases the risk of chlorophylls forming longer-lived triplet states if the energy is not passed on or
dissipated fast enough Chlorophylls in their triplet state can photosensitise toxic chemicals such as singlet
oxygen which causes photodamage18
Natural photosynthetic systems limit photodamage with a process
called non-photochemical quenching using molecules called carotenoids that quench chlorophyll triplet states
by triplet-triplet energy transfer Carotenoids in their triplet state are low energy and quickly release their
energy through heat production and do not facilitate the production of singlet oxygen1213
This method of
photoprotection has been mimicked in artificial photosynthetic systems to extend their lifetimes and enable
them to work under intense light conditions
22 Current energy usage and definition of artificial photosynthesis
The current demand for energy is primarily met by the combustion of fossil fuel resources in the form of coal
crude oil and natural gas
26
Figure 22 shows that the energy demand has doubled over the last 40 years and it should be noted that this
demand is expected to double again by 205031719
The increased energy demand could be met by increasing
fossil fuel combustion However fossil fuel combustion is not a clean process and releases large amounts of
greenhouse gases such as carbon dioxide carbon monoxide and nitrogen oxides The accumulation of these
greenhouse gases in the atmosphere is increasing the average global temperature damaging the ozone layer
and causing more extreme weather2021
From these studies it is clear that using fossil fuels to meet the future
energy demand could cause irreversible damage to the environment and the human population2223
Due to
this much time money and resources are being dedicated to find clean stable and renewable energy
alternatives to fossil fuels2425
Current candidates include wind power tidal power geothermal power and
solar energy while the viability of nuclear power is currently under discussion due to the radioactive wastes
and potential emergency risks The majority of these technologies are currently expensive to operate
manufacture and maintain and produce rather small amounts of energy due to their low efficiencies This
report will focus on how solar energy is being utilised as a renewable energy source The sun provides
100x1015
watts of solar energy annually across the surface of the earth If this solar energy could be
harnessed with 100 efficiency the current energy demand for one year could be met within an hour In total
only 002 of the total solar energy received by earth over a year would be required161726
27
Figure 22 Worldwide consumption of fuel types by percentage Total fuel consumption was equal to 4667 Mtoe in 1973 and 9301
Mtoe in 2013 and is represented by the size difference of the two charts below The figure was adapted from The 2015 Key
World Energy Statistics report3 Mtoe = million tonnes oil equivalent This figure does not state whether the energy came
from a renewable source
Currently one of the best and most developed methods of utilising solar energy (photons) is by using
photovoltaic cells that absorb photons and generate an electrical current This electrical current can be
instantly used as a source of energy or it can be stored in a wide variety of batteries for later use There are a
number of disadvantages to solely relying on photovoltaics to provide us with all of our energy requirements
which are listed below
Photovoltaics can only be used in areas that have high year-round levels of sunlight
The electrical energy has to be used immediately (unless it is stored)
Batteries used to store electrical energy are currently unable to store large amounts of energy have short
lifetimes and their production generates large amounts of toxic waste materials
To address these disadvantages researchers are looking into ways that solar energy can be stored as
chemical energy instead of inside batteries as electricity This is the point where the research being conducted
begins to draw inspiration from photosynthetic organisms14
Photosynthetic organisms have been capable of
utilising solar energy to generate a multitude of complex molecules for billions of years27
Natural
photosynthetic systems are capable of producing two main fuel types hydrogen and carbon-based fuels
Hydrogen is generated from photon-driven in PSII and carbon-based fuels such as carbohydrates and lipids
are generated from the reduction of carbon dioxide with hydrogen (Calvin cycledark reactions)1628
Hydrogen
and carbon-based fuels are the main fuel types researchers aim to produce using artificial photosynthetic
systems29
Hydrogen is produced by splitting (oxidising) water with solar energy catalysts and water oxygen
is a by-product of water oxidation Hydrogen is the simplest fuel to produce and the majority of the
technologies discussed in this report have already had success producing it It is desirable however for
researchers to generate more complex carbon-based fuels such as carbon monoxide methane methanol and
higher order carbon-based compounds using solar energy carbon dioxide and water because carbon-based
fuels have a higher energy density than hydrogen and are used as our primary energy source It should be
noted that hydrogen does not exist in its molecular form in nature which means that it must be produced by
an energy input Hydrogen is most commonly produced by steam reforming natural gas or fossil fuels such as
propane diesel methanol or ethanol8 These methods produce low purity hydrogen and consume fossil fuels
so they do not relieve any fossil fuel dependencies and they further contribute to environmental concerns
In later sections of this literature review some of the main technologies that utilise artificial photosynthesis to
generate fuel molecules are discussed These technologies offer a potential method by which high purity
hydrogen can be produced by the water-splitting reaction using energy obtained from renewable sources
Hydrogen carbon monoxide and carbon dioxide are important feedstocks for making industrial products such
as fertilisers pharmaceuticals plastics and synthetic liquid fuels With more research it is hoped that it will
soon be possible to produce complex molecules from chemical feedstocks that have been produced using
28
renewable energy Technologies that directly convert solar energy to electrical energy (photovoltaics) have
been commercialised for a number of years and can generate electricity on a megawatt scale at large
facilities Success has also been gained with generating hydrogen with a number of technologies such as
biological hybrid systems photoelectrocatalysis and electrolysers (some sub-technologies in this pathway
have been commercialised and can produce power on a megawatt scale) which will also be discussed in this
literature review Some success has been had with generating these more complicated molecules by artificial
photosynthesis from chemical feedstocks but it should be noted that these technologies are still at an early
research and development stage Using recent literature a definition for artificial photosynthesis was
developed for this study and is provided below
Artificial photosynthesis is a process that aims to mimic the physical chemistry of natural
photosynthesis by absorbing solar energy in the form of photons and using the energy to
generate fuel molecules through a synthetic system that utilises either biomimetics
nanotechnology synthetic biology or a combination of these systems
This is a broad definition of artificial photosynthesis where the term physical chemistry includes any reaction
or process that takes place during natural photosynthesis The term fuel molecules encompasses the term
solar fuel and can include any molecule that the system has been designed to produce such as molecular
hydrogen hydrocarbons alcohols and carbohydrates Biomimetics refers to a system that aims to mimic a
biological system by including some aspects of a biological system such as photosystems I and II chlorophyll
molecules or the electron transport proteinsmolecules Nanotechnology can refer to systems that use organic
chemistry inorganic chemistry or surfaceinterface chemistry to generate artificial photosynthetic systems
Synthetic biology refers to biological systems that have been genetically engineered to either allow or prevent
a biological process to occur
To date much progress has been made in the development of artificial photosynthetic systems since the
conception of the term22628-35
The most common problems associated with artificial photosynthetic systems
arise from
Low efficiency
Inability to utilise the entire spectrum of photon wavelengths
Inability to efficiently separate the charged species
Most systems use expensive noble metals to conduct the chemistry36
Short device lifetimes
Should these synthetic fuels be produced at a large enough scale for commercial use a new set of problems
would appear associated with how the fuels should be stored and distributed Using artificial photosynthesis to
generate hydrocarbons that are already used as an energy source would require fewer infrastructural changes
than switching to a hydrogen economy Furthermore the production process needs to be easily scalable so
that fuels can be produced in a cost-effective way on a terawatt scale in a manner that can keep up with the
ever-increasing energy demand In the next section several different types of artificial photosynthesis
technologies are introduced that aim to effectively utilise solar energy
29
23 Introduction to the different types of Artificial Photosynthesis technologies covered in the
study
Research and development related to the area of artificial photosynthesis encompass several technological
areas The different pathways for artificial photosynthesis are illustrated in
30
Figure 22 along with some of the compounds that can be generated from these technologies on their own or
by combining them It should be noted that while Figure 23 presents a broad selection of potential compounds
that can be produced the actual number of compounds that could potentially be generated by artificial
photosynthetic systems is limitless
Figure 23 Different routes by which artificial photosynthesis can take place and the products that can be generated by utilising the
different technologies This image was generated by The University of Sheffield PV = Photovoltaics
The efficiency and usefulness of artificial photosynthetic technologies are dependent on how well they can
perform three distinctive steps that are found in natural photosynthetic organisms namely
How efficiently they are able to capture incoming photons (percentage of the spectrum that can be
utilised)
How efficiently the system can transfer the energy to a reaction centre (minimising energy loss during the
transfer)
How well the system can generate and separate charges to allow the desired chemical reaction to take
place (preventing charge recombination)
The complexity of artificial photosynthetic systems occurs when multiple charges have to be separated for a
chemical reaction to occur The production of hydrogen and oxygen from the water-splitting reaction which is
probably the simplest reaction these systems must be capable of still involves the transfer of four electrons
and the generation of more complicated compounds will require even more charge-separation events to occur
The following sections discuss the artificial photosynthetic technologies as depicted in
31
Figure 22 which are synthetic biologyhybrid systems photoelectrochemical catalysis and co-electrolysis
231 Synthetic biology amp hybrid systems
This pathway aims to take existing biological systems that perform different stages of photosynthesis such as
the light-harvesting charge separation or molecule synthesis steps and combine them so they are able to
produce specific fuel molecules These biological molecules can be modified or combined with other biological
molecules or synthetic organicinorganic compounds so that they are able to produce specific fuel molecules
more efficiently It is known that natural photosynthetic systems contain a number of crucial components that
need to be included in synthetic biology and hybrid artificial photosynthetic systems For example they should
contain a light harvester (semiconductor or molecular dye) a reduction co-catalyst (hydrogenase mimic or
noble metal) and an oxidation co-catalyst (photosystem II mimic that is capable of producing molecular oxygen
and hydrogen) It should be noted that these technologies are at a very early stage of development
(laboratory level technology readiness level (TRL 1-4)) and are many years away from being commercialised
Briefly researchers are capable of producing small quantities of hydrogen through the water-splitting reaction
and have demonstrated the reduction of carbon dioxide to methane and acetate Researchers are also
investigating the possibility of using basic cells (biological) to host biological machinery that is capable of
generating more complex fuel molecules The long-term goal of these technologies will be to reliably generate
large quantities of specific fuel molecules from simple starting compounds such as hydrogen and carbon
dioxide which are combined and converted into a series of different compounds using a series of enzymes
and synthetic organic and inorganic catalysts
232 Photoelectrocatalysis of water (water splitting)
This pathway aims to develop efficient photovoltaics and photoelectrochemical catalysts that utilise earth-
abundant metals capable of generating oxygen and hydrogen through the water-splitting reaction38
Photovoltaics can be used to generate electrical energy directly from sunlight Photovoltaicssemiconductors
can be used in photoelectrochemical cells to produce hydrogen from the water-splitting reaction PVs and
PECs are among the most advanced areas of artificial photosynthesis Photovoltaics utilise semiconductor
materials that are capable of directly generating electrical currents (electrical energy) when exposed to certain
wavelengths of light These semiconductors have to be capable of utilising a range of photon wavelengths
efficiently and must have long lifetimes Photovoltaics have been commercialised and are producing power on
a megawatt scale Future developments in this field aim to increase device efficiency and lower the costs
associated with them (TRL 7-8) Photoelectrochemical cells are capable of producing electricity and fuel
molecules when exposed to certain wavelengths of light Fuel molecules such as hydrogen are produced by
electrolysing water (splitting water) which could provide an unlimited source of hydrogen that could be used to
generate power or reduce carbon dioxide Water-splitting cells require semiconductors that are able to support
rapid charge transfer at the semiconductoraqueous interface have long-term stability in aqueous
environments and are capable of utilising a range of photon wavelengths30
233 Co-electrolysis
This pathway provides an alternative method by which water oxidation can be performed Alkaline
electrolysers and polymer electrolyte membrane electrolysers have been mature technologies now for a
number of years and are capable of converting water and electricity to hydrogen and oxygen The co-
electrolysis pathway aims to use carbon dioxide-water co-electrolysis to generate syngas (COH2) which is
produced by simultaneously reducing carbon dioxide and water using high temperature solid oxide cell
electrolysers (SOECs)39
Syngas can be used to generate simple intermediate compounds that can be used
as feedstock for more complicated chemicals used in fertilisers pharmaceuticals plastics and synthetic liquid
fuels Methanol is an example of a simple molecule that can be made from syngas The dehydration of
methanol can be used to generate the cleaner fuel dimethyl ether which is being considered as a future
energy source40
As a technique to produce power co-electrolysis offers a number of advantages over other
techniques such as photovoltaics and wind power in that it is not site-specific and can continuously generate
32
power However these devices require large amounts of electricity to function which affects their operating
costs It is likely that these systems will have their electricity supplied to them by solar or wind power farms in
the near future
33
3 Assessment of the technological development current status and future perspective
This literature review will focus on three technologies (synthetic biologybiological hybrid systems
photovoltaicsphotoelectrochemical cells and co-electrolysis) that are currently using artificial photosynthesis
to generate energy in the form of electricity and fuels The majority of research into these technologies has
focused on improving device efficiencies lifetimes and producing hydrogen The review will conclude with
discussions about the fuels researchers are currently producing potential large-scale facilities to produce the
fuels and finally the potential directions research into artificial photosynthesis could pursue Figure 3 shows a
general development and supply chain for technologies that aim to use artificial photosynthesis to convert
solar energy into power and fuels It should be noted that each technology will have its own set of specific
challenges which will be discussed at the end of each respective section This literature review was
constructed using material from a number of sources such as peer-reviewed journals official reports and
patents that have been filed
Figure 31 General development and supply chain for technologies that aim to use a combination of photovoltaics and
photoelectrochemical cell artificial photosynthetic technologies to convert solar energy into power and fuels
34
31 Synthetic biology amp hybrid systems
311 Description of the process
Artificial photosynthetic systems that utilise synthetic biology aim to modify existing natural photosynthetic
systems at the genetic level or combine them with other biological systems and synthetic compounds to
produce a specific fuel or improve efficiency It should be noted that technologies based on using synthetic
biology and hybrid systems to produce solar fuels are still at the research and development stage (TRL 1-4)
however the use of these systems to produce a limited number of fine chemicals is more advanced with a TRL
3-7 The majority of technologies developed in this pathway have focused on producing hydrogen and only a
limited number of technologies are capable of producing more complex fuel molecules It should also be noted
that most of these systems are only capable of producing small amounts of fuel molecules for a short period of
time Natural photosynthetic systems can be broken down into three distinct processes that these systems
have to mimic light-harvesting energy transfer and charge generationseparation (catalytic reactions)1437
For
these technologies to be successful the systems have to be designed so that they consist of electron donors
and acceptors and attempt to mimic light-driven charge separation2 Generally these technologies aim to
combine biological molecules that have catalytic activity (enzymes such as PSI [NiFe]-hydrogenase and
[FeFe]-hydrogenase) or combine the enzymes with synthetic inorganic and organic compounds9 Examples of
when these systems have been successfully created are discussed below with figures and the TRLs of the
technologies are given after each technology has been discussed
Illustrations
Figure 32 A simplified diagrammatic representation of a PSI-platinum hybrid system that is used to generate H2 can be found below
showing PSI P700 chlorophyll a apoprotein A1 (red) and PSI P700 chlorophyll a apoprotein A2 (blue) The electron provided
by ascorbate is transferred to a cytochrome c6 where a photon excites the electron which is then passed through PSI where
it is transferred to the platinum (Pt) catalyst to generate molecular hydrogen This figure drew inspiration from Fukuzumi
2015 and Gorka et al 20149
35
Figure 33 A diagrammatic representation of a FeFe-hydrogenase I ndash cadmium sulphur (CdS) hybrid system that is used to generate
H2 The faded red structure represents the surface topography of FeFe-hydrogenase I the blue arrows represent the
movement of the electrons through the Fe-S clusters where hydrogen ions are converted to H2 and the yellow structures
represent the CaI capped CdS nanorods The figure was constructed using inspiration from Wilker et al 2014 using the
PBD file 3C8Y and edited using PyMol software12
312 Current status review of the state of the art
The first example of researchers successfully producing light-driven hydrogen from an artificial complex
composed of biological molecules and platinum was achieved by combining the PSI subunit PsaE from
Thermosynechococcus elongtus with an oxygen tolerant [NiFe]-hydrogenase from Ralstonia eutropha H16 to
form a PSI-hydrogenase complex This complex in presence of ascorbate (electron donor) was capable of
light-driven hydrogen production at a rate of 058 microM (mg chlorophyll)-1
h-1
41-43
(TRL 3)
Hydrogenases are enzymes that catalyse the reversible oxidation of molecular hydrogen while platinum is
also capable of reversibly photocatalytically oxidising hydrogen44
Researchers recently showed that when a
platinum nanocluster was attached to a PSI molecule the complex was able to produce hydrogen at a rate of
673 microM (mg chlorophyll)-1
h-1
- the general structure of this complex is highlighted in Figure 323
Systems
based on these original concepts have been optimised to achieve higher hydrogen production efficiencies of
up to 244 microM (mg chlorophyll)-1
h-1
It should also be noted that the electron donor (ascorbate) had to be
present in excess in both cases2345
It should also be noted that these hydrogen production rates are
comparable to those of natural photosynthetic systems which occur at a rate of ca 300 microM (mg chlorophyll)-1
h-1
46
(TRL 3-4)
Researchers recently proposed a model by which hydrogen can be generated using CaI capped CdS
nanorods The authors reported that light is absorbed by the CdS nanorods to excite two electrons which are
then transferred into the CaI cap where the two electrons are used to reduce two protons (H+) and generate
hydrogen (electrons are replaced in CdS by ascorbate) In a recent publication the authors showed that it is
possible to combine the CdSCaI nanorods with [FeFe]-hydrogenase in place of PSI (ascorbate is used as an
electron donor) In this biomimetic system the electrons are transferred to [FeFe]-hydrogenase where they
reduce H+ to hydrogen This system was shown to have a quantum efficiency of 20 be active for up to 4
hours and had a total turnover of 106 hydrogen before activity was lost The loss in activity was found to be
due to the inactivation of the CaI cap at the end of the CdS rod147
36
Figure 3 represents the system and process described above where the blue arrows represent the movement
of electrons from the CdSCaI nanorods to the iron-sulphur clusters in [FeFe]-hydrogenase (TRL 3-4)
Researchers were recently able to produce hydrogen using a PSI-cobaloxime complex when it was
illuminated with natural light Cobaloximes are vitamin B12 mimics capable of catalysing H+ reduction
Cobaloximes offer a number of advantages over hydrogenases in that they are not sensitive to oxygen their
synthesis is relatively simple and they are constructed from relatively cheap materials In this system sodium
ascorbate used a sacrificial electron donor and cytochrome c6 transported the electrons to the PSI-cobaloxime
complex Upon light absorption the electrons were excited and transported through PSI to the bound
molecular catalyst cobaloxime where hydrogen production occurs27
The maximum rate for the photoreduction
of water by this hybrid system was measured to be 170 mol hydrogen (mol PSI)-1
min-1
as was reached within
10 minutes of illumination It should be noted that after 90 minutes hydrogen production levelled off giving a
total turnover of 5200 mol hydrogen mol PSI-1
27
It is thought that the activity of the hybrid decreased due to
the dissociation of cobaloxime from PSI research efforts are currently underway to stabilise the hybrid
system27
This system is of particular merit because the PSI-cobaloxime hybrid is composed of earth-
abundant materials unlike the hybrid systems containing precious metals It should also be noted that there
are multiple molecular catalysts for hydrogen production other than the cobaloximes that can offer improved
stability solubility in water and better activity and have been discussed in a recent review6 (TRL 3-4)
The production of hydrogen at a rate of 2200 plusmn 460 micromol mg Chl-1
h-1
(a faster rate than natural photosynthetic
systems) has recently been demonstrated This was accomplished by generating a hybrid system consisting
of a PSI complex tethered to a [FeFe]-hydrogenase using a 18-octanedithiol nanowire and also crosslinking
cytochrome c6 to the PSI complex This four component system was then placed in a sodium phosphate buffer
containing the electron donor sodium ascorbate at pH 65 and illuminating the sample with natural light48
The
authors also reported results for complexes consisting of different nanowire lengths (3-10 carbons) and a
chain length of 8 carbons was found to give the highest hydrogen production rates this is most likely due to
the chain being long enough to minimise steric hindrance between the two proteins The hybrid system
retained its activity for up to four hours and it should be noted that the decrease in activity was attributed to
depletion of the electron donor (full activity was regained upon replenishing the ascorbate) It should also be
noted that the hybrid system regained its full hydrogen-evolving activity after being stored in anoxic conditions
at room temperature for 100 days48
(TRL 3)
The technologies above are only a few examples of the methods researchers have used to generate hydrogen
from hybrid systems Table 31 below summarises hydrogen production rates by a number of different hybrid
systems that all incorporate PSI into their complex The information in Table 31 was originally summarised by
Utschig et al 20156 All of the technologies in this table have a TRL of 3-4
Table 31 Rates of light-driven hydrogen production and turnover numbers for PSI-Catalyst hybrid systems
PSI-catalyst system Rate of H2 production
[mol H2 (mol PSI)-1 s
-1]
TON (time hours)
PSI-nanoclusters photoprecipitated long liveda 49
0002 ndc (2000)
PSI-[NiFe]-hydrogenase genetic fusion 41
001 ndc (3)
PSI-nanoclusters photoprecipitated short-liveda 49
013 ndc (2)
PSI-[FeFe]-hydrogenase-PetF in vitro complexb 50
031 ndc (05)
PSI-Ni diphosphinea 51
073 (3)
PSI-[FeFe]-hydrogenase-Fd protein complexb 50
107 ndc (1)
PSI-molecular wire-Pt nanoparticlea 52
11 (12)
PSI-NiApoFd protein deliverya 51
125 (4)
PSI-cobaloximea 27
283 (15)
PSI-Pt nanoparticlea 45
583 (4)
PSI-molecular wire-[FeFe]-hydrogenasea 48
524 ndc (3)
a Redox mediator Cyt c6
b Redox mediator PC
c nd not determined
37
Researchers have generated a hybrid photocatalyst system capable of splitting water to produce hydrogen
and oxygen and capable of reducing carbon dioxide by rational design The system uses a semiconductor as
the light harvester and a biomimetic complex mimicking photosystem I as a molecular catalyst37
This work
highlights that the understanding of artificial photosynthetic systems is increasing as rational design can now
be used to construct biomimetic artificial photosynthetic systems (TRL 2)
Unicellular organisms such as Chlamydomonas reinhardtii are a type of green algae that can produce
hydrogen light-dependently using the enzyme [FeFe]-hydrogenase However hydrogen production rates in
photoactive organisms are limited by a number of physiological constraints This is due to electrons
generated by PSI being used in a number of reactions other than hydrogen production5354
Most photoactive
organisms will contain a form of photosynthetic electron transport ferredoxin (PETF) protein which provides
photosynthetic electrons generated by PSI for a number of metabolic pathways All of these pathways
compete for electrons with [FeFe]-hydrogenase Researchers recently genetically modified the affinity PETF
has for PETF-dependent ferredoxin-NADP+-oxidoreductase (FNR) without comprising the affinity PETF has
for [FeFe]-hydrogenase In this modified system PETF is still able to supply [FeFe]-hydrogenase with
electrons that it used to produce hydrogen but is less able to supply electrons to FNR which means that fewer
carbon dioxide fixation reactions occur Hydrogen production rates increased by nearly 5x in wild type cells
that had modified PETF53
(TRL 3)
Microbial biocathodes consist of an electrode that has electrochemically active microorganisms immobilised
onto its surface which are capable of reducing protons to hydrogen These systems offer a number of
advantages in that the cathode can be constructed from cheap materials and the microorganisms can self-
regenerate55
The first microbial biocathode consisted of three phases (1) acetate and hydrogen are oxidised
at a bioanode that has been inoculated with a mixed culture of electrochemically active microorganisms to
release carbon dioxide (2) only hydrogen is fed into the bioanode (3) the polarity of the cells is reversed
(direction of electron flow) and hydrogen production begins at the cathode55
Initially after the polarity is
reversed methane was produced at the biocathode and not hydrogen (TRL 4)
Bio-catalysed electrolysis is a microbial fuel cell-based technology that is capable of generating hydrogen and
other reduced products from electron donors (acetatewastewater) however these systems require an
external power source56
In this system acetate is oxidised at the anode by microorganisms in the presence of
high concentrations of ammonium and the electrons are transferred to a platinum catalyst (cathode) where
they reduce protons to hydrogen56
(TRL 3)
A recent paper has reported the reduction of carbon dioxide to acetate and methane using a water-splitting
reaction to produce hydrogen and sodium bicarbonate as the carbon source using microbial electrosynthesis
(MES)57
This system used an assembly of graphite felt and a stainless steel cathode This paper is important
because it presents the use of electrode materials derived from earth-abundant elements showcasing them
as particularly suitable for industrial scale-out due to their low cost (TRL 3)
Researchers at the University of Oxford developed a biological tool called ldquoSimCellrdquo A SimCell is a simple
non-replicating cell that has no well-defined function until a plasmid containing DNA coding a specific
function is inserted into the cellrsquos genome The inserted DNA could potentially provide all of the genetic
information needed by the cell to produce the proteins and enzymes required to produce specific fuel
molecules The SimCell has been optimised to be simple so that most of the energy the cell is using will go
towards carrying out the function of the newly inserted gene instead of maintaining numerous intracellular
processes5859
The SimCell could allow researchers to insert genetic information that codes the production of
target fuels thereby greatly increasing the number of potential fuel targets and the efficiency with which they
can be produced It is possible that this technology could be patented once it reaches a higher level of
maturity and a working system is demonstrated (TRL 1)
38
313 Future development main challenges
Synthetic biology amp hybrid artificial photosynthetic systems primarily focus on producing hydrogen however
research focused on the production of hydrocarbons using technologies such as MES is gaining momentum
Although these technologies are currently at the laboratory research and development stage (TRL 1-4) they
are improving quickly At a very small laboratory scale the systems are becoming efficient enough to produce
hydrogen at a rate that is comparable to that which occurs in natural photosynthesis although some
researchers have reported even faster production rates
Synthetic biology amp hybrid systems need to address a number of specific challenges before they can be
considered as commercially viable options for producing solar fuels Below some preconditions and
challenges regarding certain such systems are described
Protein Hybrid Systems
For proteins to be active their primary amino acid sequence must fold and adopt the correctly folded
structure Misfolded proteins can exhibit severely diminished activities
Proteins (and enzymes) are inherently unstable and sensitive to the pH temperature pressure and buffer
components and will often degrade over time which limits their use
Most hydrogenases are sensitive to oxygen so they must be kept under anaerobic conditions
Biological molecules can be produced at a large scale as shown by the biopharmaceutical industry
However the amount of biological molecules needed to produce the amount of fuel required to support
mankind would be huge and has not been calculated
One of the strongest properties of enzymes is that they exhibit a high level of specificity they are able to
produce specific molecules of high purity
Enzymes can be redesigned to give them new or improved functions within different environments60
However modifying protein and enzyme function is not trivial it is often a time-consuming process that
requires thorough understanding of the system although predictive tools for protein engineering are
improving
Enzymes are often very large molecules in which only a small percentage of the amino acid residues are
actively involved in catalysis Researchers could reduce the complexity of biological systems drastically if
they focused on stripping the enzyme down so it contains only the residues and cofactors needed for
catalytic activity on a simplified base framework of amino acids
Microorganisms
In a recent paper researchers investigated how hydrogen production can be enhanced and suppressed in
vitro They state that the main limitations of hydrogen production in microorganisms are the systemrsquos
sensitivity to oxygen and the competition between hydrogenases and NADPH-dependent carbon dioxide
fixation If these issues can be solved the technologies would be closer to commercialisation50
It should be
noted that microorganisms are capable of producing a number of fine chemicals on a commercial scale (these
are often produced in smaller amounts)
Microorganisms are highly complex in that a multitude of chemical reactions must take place so that the
organism can continue to function at the most basic level These extra reactions are major drawbacks if
these organisms are to be used to produce fuel molecules as most of the absorbed energy cannot be
used to produce the fuel molecules
To overcome this problem various aspects of the organismsrsquo genetic information can be modified to
minimise energy loss through side reactions
SimCells are simplified cells in that number of chemical reactions needed to sustain the organism are
minimised this means that more energy can dedicated to fuel production However these technologies
are currently in early stages of research and development and are not close to being produced on an
industrial scale
39
It is likely that fuel-producing microorganisms will have to be capable of expelling the fuel molecules
otherwise the fuel-producing cells will have to be destroyed to obtain the molecules
A major advantage of bacterial systems is that their genetic information can be modified so that they
produce a number of different fuel molecules However this is not a trivial task and the microorganisms
may not be able to survive when large concentrations of the fuel molecules are present
Bacterial cells can survive in a number of harsh conditions and they do not have to be in an ultra-clean
environment
Synthetic biology and hybrid systems face a unique challenge in that these systems are made by or are
genetically modified organisms (GMOs) GMOs are often subject to negative media attention and are often
portrayed and viewed to be unsafe by the public which means that the public may not want their fuel coming
from this source Some of the concerns surrounding the use of GMOs are valid and need to be investigated
One of the main concerns about the use of GMOs pertains to whether the GMO could have a severe effect on
the environment if it managed to migrate into the wild However this issue could be addressed by only using
GMOs that are not able to replicate (ie they are obtained from a secured parent cell) However most of the
concerns the public may have regarding GMOs could be solved by educating about GMOs and providing a
large body of scientific evidence that supports their safety
It should be noted that the authors could find no relevant patents for artificial photosynthetic technologies that
utilise synthetic biology amp hybrid systems
In conclusion synthetic biology amp hybrid systems that produce solar fuels are currently in the laboratory
research and development stage and it is too early to determine whether they would be a commercially viable
option However current research is promising and shows that they could be a valuable part of generating
solar fuels due to their high level of specificity and ability to be reengineered to carry out new and specialised
chemistry
32 Photoelectrocatalysis of water (water splitting)
321 Description of the process
This pathway aims to develop efficient photovoltaics and photoelectrocatalysts that utilise earth-abundant
metals capable of generating oxygen and hydrogen by splitting water38
The water-splitting (water oxidation)
reaction is one of the most advanced areas of artificial photosynthesis These systems that directly produce
fuel molecules from sunlight are currently in the early researchproof-of-concept stage (TRL 2-4) This means
that they are a number of years away from being a commercially viable method to produce synthetic fuels31
Water oxidation involves the removal of 4e- and 4H
+ to generate molecular oxygen (O2) and molecular
hydrogen (H2) In nature water oxidation is carried out by photosystem II in natural photosynthetic systems
The water-splitting reaction has the potential to provide a clean sustainable and abundant source of
hydrogen that could be used as energy or to reduce carbon dioxide to higher order hydrocarbons which is
why a considerable amount of time and money has been spent trying to improve the process
Photovoltaic cells (PVs) also known as solar cells utilise semiconductor materials that are capable of directly
generating electrical currents when exposed to certain wavelengths of light Light absorption by the
semiconductor promotes an electron from the low energy valence band to the higher energy conduction band
This creates an electron-hole pair that can be transported through the electrical device to provide power
Research focusing on PVs has focused on improving their efficiencies Initially efficiencies lt1 were
obtainable but the most recent generation of PVs can achieve efficiencies gt45 Research has shown that
the efficiencies of PVs can be greatly improved by using multi-junction instead of single-junction devices60
Efficiencies of different PV models have increased over the last 40 years this plot is courtesy of the National
Renewable Energy Laboratory Golden CO The most recent PVs have long lifespans (gt20 years) low
40
pollution levels and low operating costs30
However PVs do have some drawbacks in that they are expensive
to manufacture can only be used during the day in areas that receive a lot of sunlight utilise a fraction of the
available spectrum and it is problematic to store the energy in batteries3360
Problems associated with long-
term storage of energy could be overcome by storing the energy in chemical bonds of molecules such as
hydrogen alcohols and hydrocarbons which is why the research in the following section is of importance It
should also be noted that PVs have a TRL of 9 as they have been successfully commercialised and can
provide power on a megawatt scale
Photoelectrochemical cells (PECs) are capable of producing fuel molecules when exposed to certain
wavelengths of light or paired with a semiconductor (PV) Hydrogen can be produced by the water-splitting
reaction Figure 3 shows a schematic diagram of a PEC which is capable of conducting water oxidation in
two separate chambers Currently there are two primary methods by which solar fuels can be generated from
the water-splitting reaction in PECs The first is by direct photoelectrocatalysis at the semiconductor-
electrolyte interface (occurring at a solid-liquid junction) and the second is by coupling the electrochemical
(PEC) reaction directly to a buried p-n junction PV230
Both of these approaches require the generation of a
photovoltage sufficient to split water (gt 123 V)30
Photoelectrodes in PECs must have high surface stability
good electronic properties and suitable light absorption characteristics Water-splitting cells require
semiconductors that are able to support rapid charge transfer at the semiconductoraqueous interface have
long-term stability in aqueous environments and are capable of utilising a range of photon wavelengths30
These functions are obtained by using multi-junction configurations that use p- and n-type semiconductors
with different band gaps and surface-bound electrocatalysts The brief description of PVs has been included
because they are an essential component for a number of systems that photocatalytically split water
Illustration
Figure 34 The illustration below shows a photoelectrochemical cell capable of water oxidation using solar energy consisting of
separated titanium dioxide (TiO2) and platinum (Pt) electrodes Water oxidation occurs at the TiO2 electrode where oxygen
is formed during which process protons (H+) and electrons (e
-) are released H
+ pass through an ion transport membrane to
a compartment containing the Pt electrode where electrons are used to reduce H+ to hydrogen After this hydrogen can be
stored as an energy source or it can be used to reduce carbon dioxide to higher order hydrocarbon compounds
Explanations
According to the National Renewable Energy Laboratory the greatest gains in efficiency have been made with
the multi-junction PV cells The first single-junction GaAs cells developed in the mid-1970s and had
efficiencies of ca 22 (which is better than most of the more recent PV cells that have been developed) The
most recent multi-junction technologies have achieved efficiencies of up to 46 It should also be noted that a
41
greater number of p-n junctions a PV has the greater its efficiency This is because each p-n junction is made
from a different semiconductor material that can absorb light at a different wavelength increasing the amount
of the spectrum that can be utilised PVs based on crystalline silicone cells have shown a slow increase in
efficiency over the last 40 years starting from 14 and increasing up to 276 PVs utilising thin-film
technologies now achieve efficiencies up to 223 Thin-film technologies are a particularly promising branch
of PV due to them being lightweight and the potential to manufacture them by printing which would decrease
their production and installation costs
Figure 3 shows a schematic diagram of a PEC cell that was developed by Honda and Fujishima in 1972 and
was capable of the water-splitting reaction using a TiO2 electrode in tandem with a platinum electrode61
PEC
cells consist of three basic components a semiconductor a reference electrode and an electrolyte The
principles of PEC cell operation are simple a photon is absorbed by the semiconductor (TiO2) material which
causes electron excitation and the excited electrons move to the reference electrode (Pt) through a metal
wire The movement of electrons between the two materials generates a positive charge (holes) at the
semiconductor which combines with electrons in the oxygen molecules of water to form molecular oxygen
and hydrogen ions At the reference electrode the electrons can combine with hydrogen ions to form
molecular hydrogen In this study oxygen was generated at the TiO2 electrode and hydrogen was generated at
the platinum electrode
Since the initial study by Honda and Fujishima researchers have spent much time developing new materials
for anodic and cathodic processes that are capable of carrying out the same process with greater efficiency
and ability to produce more products3061
Currently the cost-effectiveness of using solar energy systems to
generate power and fuels is constricted by the low energy density of sunlight which means low cost materials
need to be developed so that enough sunlight can efficiently be captured Sunlight availability is intermittent
which means that the captured energy needs to be efficiently stored The efficiency of PEC water-splitting
devices is determined by measuring their solar-to-hydrogen (STH) efficiency this is defined as the amount of
chemical energy produced in the form of hydrogen divided by the solar energy input without the use of any
external bias10
322 Current status review of the state of the art
Currently there are two main approaches that are used to photocatalytically split water into oxygen and
hydrogen The first method utilises a single-visible-light photocatalyst (this is essentially a PV) with a narrow
band gap capable of absorbing photons in the visible spectrum has a suitable thermodynamic potential for
water splitting and is stable enough to avoid photocorrosion4 The drawbacks of this system include that it is
only capable of utilising a small region of the spectrum and the collection of oxygen and hydrogen is difficult
due to them being produced in the same region2 The second method uses a two-step mechanism which
utilises two photocatalysts (photoanode and photocathode) in tandem similar to the Z-scheme present in
natural photosynthetic systems2 This setup enables the system to utilise a larger range of visible light
because the free energy required to drive each photocatalyst can be tuned compared to the one-step system
(one photon is needed for each photocatalyst) In this system the oxygen and hydrogen generated via water
oxidation can be separated more efficiently from each other because they are produced at different sites
(oxygen is produced at the anode and hydrogen is produced at the cathode) this also reduces the likelihood
of charge recombination462
This second system is more desirable as the oxygen and hydrogen evolution
sites can be contained in separate compartments62
Theoretical calculations have highlighted that the
maximum efficiency of a single absorber PEC system could reach 29-31 whereas a tandem PEC system
could reach 40-41 further highlighting the advantages of using tandem devices106364
Efficiency calculations
for three different PEC configurations a single photoabsorber system a dual stacked photoabsorber system
and a dual side-by-side photoabsorber system were reported to be 112 228 and 155 respectively
These systems differ in the spatial distribution and number of photoabsorbers which will affect the range of
wavelengths that can be absorbed and therefore the materialsrsquo STH efficiency10
It should be noted that the
practical efficiencies of these devices will often be much lower due to the inefficiencies associated with the
catalysts and reaction overpotentials10
These calculations show that the best way to achieve higher
efficiencies in PEC devices is to use a dual stacked photoabsorber system
42
Recently four PEC reactor types were conceived to represent a range of systems that could be used to
generate hydrogen from solar energy Each system design can be seen in Figure 31062
Types 1 and 2 are
based on relatively simple photoactive nanoparticle suspensions whereas types 3 and 4 are based on more
complex planar arrays a brief discussion of each system is given below It should be noted that quoted STH
efficiencies are optimised values and do not take into account material lifetimes
Figure 35 The figure below shows four PEC reactor types including a (a) Type 1 reactor showing the plastic bags containing the
suspended hydrogen- and oxygen-evolving photoactive particles (b) Type 2 reactor showing the plastic bags containing
separated suspensions of photoactive particles capable of separately evolving hydrogen and oxygen (c) Type 3 reactor
showing a sun-orientated panel containing a layered PEC cell capable of producing hydrogen and oxygen and (d) Type 4
reactor the design of which consists of a similar layered PEC cell to Type 3 with an added parabolic receiver that is able to
concentrate light onto the PEC cell throughout the day These figures were originally constructed by Pinaud et al 201310
Type 1 This reactor has the simplest design It consists of a transparent plastic bag that contains a
suspension of photoactive particles in 01 M potassium hydroxide that are capable of simultaneously
evolving hydrogen and oxygen by the water-splitting reaction Photons at a variety of different wavelengths
are able to penetrate the plastic bag whereas the electrolyte evolved gases and photoactive particles are
held within the bag The authors modelled the photoactive particles as spherical cores coated with
photoanodic and photocathodic particles The authors calculated that this reactor type could achieve a
realistic STH efficiency of 10 however it should be noted that the hydrogen and oxygen evolved in this
system would need to be separated1062
43
Type 2 The design of this reactor is very similar to that of Type 1 in that it consists of photoactive
nanoparticles suspended in an electrolyte contained within clear plastic bags The main difference
between the two systems is that the hydrogen- and oxygen-evolving particles are contained within
separate bags which reduces the need for a gas separation step and increases the safety of the system
However the bag design has to be more complicated in that a redox mediator is required along with a
porous bridge between the hydrogen- and oxygen-evolving bags The STH efficiency of this system was
calculated to be 51062
Type 3 This reactor is composed of a layered planar electrode consisting of multiple photoactive layers
(multi-junction PVsemiconductor) that is submerged within an aqueous solution containing 01 M
potassium hydroxide encased within a clear plastic case Multiple photoactive materials are used so that
more of the solar spectrum can be utilised The anode (oxygen evolution) is at the top of the cell where it
absorbs photons of a certain wavelength and allows others to pass through to the cathode where they are
absorbed into another layer to drive hydrogen evolution Due to the fixed orientation of these cells they
have to have a large surface area to ensure they can absorb the maximum amount of photons1062
Type 4 This reactor is similar to Type 3 in that it consists of a flat PEC cell of a similar design (gas
evolution occurs in a similar manner) The main difference is that a solar tracking concentrator system is
used to focus sunlight onto the PEC cell This means that smaller and more efficient PEC devices can be
used to reduce costs The STH efficiency of this system was calculated to 12-181062
The costs of hydrogen production for a power plant consisting of each reactor type were assessed (it should
be noted that costs for Type 3 and 4 plants were considered to be more accurate due to availability of PV
pricing)10
Type 1 $160 H2kg
Type 2 $320 H2kg
Type 3 $1040 H2kg
Type 4 $400 H2kg
During early work with PEC cells researchers were able to achieve efficiencies of 124 for hydrogen
production over 20 hours using a p-GaInP2(Pt)rsquoTJGaAs electrode However it should be noted that current
density decreased from 120 mAcm2 to 105 mAcm
2 over the course of the experiment which was caused by
damage to the PEC cell65
Therefore although this device was able to achieve high efficiencies its lifetime
was too low
Water oxidation in the presence of a photocatalyst that has been combined with a co-catalyst has been
reported2 The role of the co-catalyst is to provide extra reaction sites and decrease the activation energy for
oxygen and hydrogen evolution Researchers must carefully choose the type of co-catalyst to use this is
because although some noble metal catalysts like platinum and rhodium are good for enhancing hydrogen
production they also catalyse the reverse reaction (convert oxygen and hydrogen back to water)66
To
circumvent this issue transition-metal oxides are often used as co-catalysts instead of noble metals as these
do not catalyse water reformation However these compounds are often more susceptible to degradation
when they are exposed to the reactive environments found in PECs4
The first example of a metal oxide being used to split water into oxygen and hydrogen was carried out by a
dinuclear ruthenium complex (the blue dimer)34
Electrochemical and in situ spectroscopic measurements
were used to measure hydrogen production when platinum and rhodium plates deposited with chromia
(Cr2O3) were used as the water-splitting material4 Coreshell-structured nanoparticles that have a noble metal
or noble metal oxide core and a Cr2O3 shell have been shown to be capable of acting as a co-catalyst for the
water-splitting reaction This presents a mechanism by which noble metals could be used as co-catalysts the
Cr2O3 shell has been shown to supress the water reformation reaction when coated onto palladium and
platinum cores4 Multiple transition metal oxides such as NiOx RuO2 and TiO2 can be used as co-catalysts
when they are treated with appropriate chemicals (TRL 3-4)
44
Researchers recently reported a catalyst that was formed upon the oxidative polarization of an inert indium tin
oxide electrode immersed in a solution containing 100 mM potassium phosphate and 05 mM cobalt (II) ions at
pH 70 Upon initiation of electrolysis at 129 V oxygen production was shown to increase linearly over 12
hours to reach a maximum of 100 microM h-1
(after 12 hours electrolysis was stopped)67
The catalytic activity of
the reaction was also shown to be pH-dependent which suggests that the hydrogen phosphate ion is the
proton acceptor (TRL 3)
In a recent publication a multi-junction design was used to absorb light and provide energy for the water-
splitting reaction Multi-junction PVs are more efficient as they are able to absorb enough solar energy to
provide the free energy for water splitting The researchers developed a device based on an oxide
photoanode (Fe2O3 or WO3) and a dye-sensitized solar cell which performs unassisted water splitting with an
efficiency of up to 31 STH Incoming light was absorbed by the photoanode where the water-splitting
reaction and oxygen evolution takes place Electrons were transported to a platinum cathode where hydrogen
formation occurred68
(TRL 4)
Recently researchers demonstrated water splitting using tandem PEC cells where PtCdSCGSACGSe was
used as the photocathode (hydrogen evolution) and NiOOHFeOOHMoBiVO4 as the photoanode (oxygen
evolution) The cell was able to sustain a stable water-splitting reaction for 2 hours with an STH efficiency of
06769
(TRL 3)
Photochemical hydrogen production by nanowire arrays has been shown to be advantageous to more
traditional system designs because they use less precious material to produce7071
Researchers recently
showed that photoelectrochemical hydrogen production from water was possible using InP nanowire arrays In
these systems the chosen nanowire compound has a layer of silicone oxide (SiO2) deposited onto its surface
and then a co-catalyst deposited onto the surface of Efficiencies of 52 and 64 were obtained when the
InP nanowires were deposited with platinum and MoS3 respectively7072
Silicon is an abundant low-cost
semiconductor commonly used in PV devices and photoelectrochemical hydrogen generation at the
Sielectrolyte interface has been extensively studied for decades Hydrogen is evolved slowly at the
Sielectrolyte interface which has led to research efforts to modify the surfaces with electrocatalysts such as
platinum and ruthenium which are showing good activities and efficiencies71
(TRL 2-3)
323 Patents
Patents have been filed for systems based on nanoparticle suspensions and PECs some of which are
discussed below
A patent was filed in 2012 detailing a suspension of photoactive nanoparticles consisting of metallic cores and
semiconductor photocatalytic shells that can photocatalytically split water to directly obtain hydrogen The
efficient and unassisted photocatalytic splitting of water by the nanoparticles is based on resonant absorption
from surface plasmon in the metal coresemiconductor shell hybrid nanoparticles which can extend the
absorption spectra towards the visible-near infrared range This increases the solar energy conversion
efficiency When the photoactive nanoparticles are used in combination with scintillator nanoparticles the
hybrid photocatalytic nanoparticles can be used to convert nuclear energy into hydrogen73
(TRL 3-4)
A patent was recently filed for a PEC cell consisting of melanin melanin precursors melanin derivatives
melanin variants melanin analogues natural or synthetic pure or mixed with organic or inorganic compounds
metals ions drugs that act as the water electrolyzing material This technology uses solar energy as the sole
or main source of energy to produce hydrogen from water The system integrates a semiconductor material
and a water electrolyser inside a monolithic design that produces hydrogen directly from water using light
between 200 to 900 nm as the main or sole source of energy The technology aims to meet two criteria (i) the
system or light-absorbing compound should generate enough energy for the water-splitting reaction to be
45
completed and (ii) the materials need to be cheap to source and exhibit high stability in water and the reactive
environment The authors claim that all of these requirements can be met by melanin and related compounds
which represents a significant advancement in PEC design The technology can be used to generate
hydrogen oxygen and high energy electrons It can also be used to perform the opposite reaction and
generate water from electrons protons and oxygen and can be coupled to other processes generating a
multiplication effect It can also be used for the reduction of carbon dioxide nitrates and sulphates or others74
(TRL 2-3)
In 2008 a patent was filed describing a PEC system that could produce hydrogen from water The device was
comprised of (i) an electrolytic bath containing an electrode for catalytic oxidation an electrode for catalytic
reduction and an ion separation film disposed between the two electrodes immersed in an aqueous
electrolyte solution and (ii) a photoelectrode positioned outside the electrolytic bath and electrically connected
to the two electrodes This PEC system is characterised by disposing a photoelectrode at a position which
does not contact the electrolyte solution preventing the lowering of the photoelectrode activities and which
maximises hydrogen production efficiency75
(TRL 3)
In 2014 a patent was filed describing an invention that was able to generate hydrogen by
photoelectrocatalytic water splitting The system also incorporated an analysis-detection system The system
was composed of a photoelectrocatalytic water-splitting hydrogen generation device constructed from TiO2
nanorods (water splitting) a platinum cathode and a AgAgCl reference electrode submersed in a 05 M
Na2SO4 solution Results from five tests of the system were reported After the first hour the device produced
17-20 micromolh hydrogen for four hours as determined by the inbuilt detector76
(TRL 3)
324 Future development main challenges
The generation of electricity from solar energy by PVs has been successfully commercialised with the most
recent solar projects being able to produce electricity at a cost of 015 ndash 035 $kWh on a megawatt scale31
Facilities such as the Solar Star Power Station and the Topaz Solar Farm in the USA are examples of facilities
that use PV technologies that are capable of producing electricity (TRL 8-9) These facilities can now be
constructed because the cost of PVs has dramatically decreased and their efficiencies have increased over
the last few years Laboratory research is currently focused on further increasing the efficiency of PVs and
combining these systems with catalysts that are capable of generating higher order hydrocarbon fuels
However the reduction of carbon dioxide to liquid fuels is a complicated multi-electron process still in the
proof-of-concept stage (TRL 2-3) It is also recommended that the new materials PVs are constructed from
should ideally be cheap abundant lightweight flexible and robust If all of these requirements are met the
costs associated with manufacturing PVs as well as transporting installing and maintaining them may
continue to fall
There are a number of general challenges facing PEC technologies (including suspensions of photoactive
nanoparticles and PECs) that are associated with
Effectively designing facilities
Developing methods to store the generated energy
Developing transportation networks to distribute the energy
A major drawback of these facilities is that they can only be used during daylight hours when there is a clear
sky This highlights the importance of being able to store large amounts of energy at these facilities that can
be used outside of daylight hours It has been proposed that the energy generated from these facilities could
be stored in new types of batteries or as chemicals such as hydrogen and hydrocarbons Storing the energy
in the form of hydrocarbons would be particularly useful as these have a much higher energy density than
batteries and hydrogen The infrastructure to store and transport these already exists for them to be used as a
fuel However as previously mentioned the ability to convert hydrogen and carbon dioxide into high order
hydrocarbons using PVs and PECs is still in the proof-of-concept stage10
46
There are also a number of challenges related to the materials used to construct photoactive nanoparticles
and PECs This is particularly problematic because the most useful semiconductors are not stable in water
and the metal oxides that are stable in water often have band gaps that are too large for light absorption1065
There are three main processes that cause electrodes to degrade over long periods of time and inhibit their
activity
The first is corrosion which occurs with all materials over long periods of time
The second is catalyst poisoning which is caused by the introduction of solution impurities and it has
been shown that low concentrations of impurities can have a huge impact on electrode efficiency77
Finally changes to the composition and morphology (structurestructural features) of the electrode can
decrease their efficiency30
As well as exhibiting high stability the materials have to be highly efficient However there is a relationship
between device complexity cost and efficiency Water-splitters using triple-junction amorphous silicon or IIIndashIV
semiconductors have good efficiencies (5-10) but have high costs and device complexities Simpler
approaches using oxide-based semiconductors in a dual-absorber tandem approach have reported STH
conversion efficiencies up to 0368
This highlights the need to find cheaper and efficient semiconductor
materials that can be used for the water-splitting reaction
The US Department of Energy has determined that the price of hydrogen production delivery and dispensing
must reach $2-3 kg-1
before it can compete with current fuels2 It is also important to take into account the
infrastructural changes that would be required if we were to adopt a hydrogen fuel economy To meet the
current power demands of the US with PVs that have an efficiency of 10 a total area of 58000 miles2 would
be required The cost of semiconductors capable of these efficiencies amounts to tens of trillions of dollars
not taking into account the huge costs associated with the required changes to the infrastructure32
These
facilities would only be viable in areas where there is an abundance of sunshine (such as deserts) which also
proposes large fuel transportation issues In the majority of areas the sun is intermittent and only provides
about 6-10 hours of sunshine per day This further highlights the need to be able to store the energy in the
form of chemical bonds that can be used at any time as well as be more easily stored as batteries can only
store a relatively small amount of the energy required and can produce large quantities of toxic materials when
manufactured
It has been calculated that for the water-splitting reaction to provide one third of the energy required by the
human population in 2050 10000 solar plants each covering a 5 km x 5 km area (250000 km2 = 1 of the
Earthrsquos desert area) and with an overall efficiency of 10 would be required Each plant would be capable of
generating ca 570 tonnes of hydrogen from 5100 tonnes of water per day which together could provide up to
33 of the energy needed by mankind in 2050 The hydrogen could be transported directly to on-site
chemical plants where other organic compounds can be manufactured4 Figure 3 shows two diagrams of one
of these sites that could be capable of producing 570 tonnes of hydrogen per day24
The amount of each
material needed to generate methane from hydrogen and carbon dioxide is given in the formula below in
tonnes The US Department of Energy has set a target for hydrogen-producing PEC devices to have an STH
efficiency of 10 and a 5000 hour durability by 201878
120784119815120784 + 119810119822120784 rarr 119810119815120786 + 119822120784
120784(120784120790120787) + 120788120784120789120782 rarr 120784120784120790120782 + 120786120787120788
According to these calculations 6270 tonnes of carbon dioxide would be required by each of these plants per
day to use all of the hydrogen generated to produce 2280 tonnes of methane and 4560 tonnes of oxygen
The amount of carbon dioxide required increases linearly as the hydrocarbon chain length increases The cost
of manufacturing the number of PEC cells required to carry out this amount of water splitting would be in the
tens of trillions of euros taking into account the current costs of the associated technology62
The energy
required to power these facilities would be obtained from renewable sources such as wind wave and PVs
47
Figure 36 Potential schemes for the large-scale production of H2 using solar water-splitting photoelectrochemical cells H2 generated
on-site could be used to reduce CO2 to higher order hydrocarbon fuel molecules These figures were constructed by Maeda
et al 2010 and Tachibana et al 2012
33 Co-electrolysis
331 Description of the process
Electrolysers capable of conducting the water-splitting reaction have existed for centuries Water electrolysers
are capable of converting water and DC electricity into gaseous hydrogen and oxygen according to the
equation below879
High-pressure (30 bar) water electrolysers have been commercially available since 1951
In 2012 there were at least 13 manufactures that produce low temperature water electrolysers (3 using
polymer electrolyte membranes (PEM) and 3 using alkaline electrolysers)79
Electrolysers that use solid oxide
electrolysers cells (SOECs) under high temperatures were first developed in the 1980s in the HotElly project
Currently SOEC technologies are still in the research and development stage It should also be noted that the
water splitting thermodynamics are more favourable at the higher temperatures used in SOECs as compared
to alkaline electrolysers PEMs and PECs ΔG = 237 kJ mol-1
(123 eV) at ambient temperatures ΔG = 183 kJ
mol-1
(095 eV) at 900 oC
8397980
120784119815120784119822 + 119811119810 rarr 120784119815120784 + 119822120784
Co-electrolysis is a technique that can be used to produce fuel molecules directly from electricity water and
carbon dioxide Interest in the electrolysis of water and carbon dioxide originated in the 1960s where it was
thought that the process could be used to supply oxygen for submarines and spacecraft81
Unlike electrolysis
co-electrolysis aims to simultaneously split water and reduce carbon dioxide to form a mixture of carbon
monoxide (CO) hydrogen and oxygen this process is highlighted in the equation below The term ldquosyngasrdquo
(synthesis gas) refers to a mixture of carbon monoxide and hydrogen and not the oxygen component
Producing fuels by co-electrolysis consists of three main stages carbon dioxide capture syngas synthesis
and storage of the renewable energy as chemical bond energy (hydrogen and hydrocarbon fuels)80
This
chemical reaction is achieved by using high temperature solid oxide cell electolysers3982-84
Co-electrolysis
offers a number of advantages over solar and wind power farms Solar and wind power farms have to be built
in site-specific areas to maximise their power output which limits the number of countries that would be able
to host these technologies (solar power is only viable for countries that have high levels of sun year-round)
Solar and wind power farms are only able to generate power intermittently which makes them unsuited to
coping with sudden large power demands (solar farms can only generate power during daylight hours) It has
been suggested that batteries and thermal fluids could be used to store energy for peak times However
48
these storage methods are currently unable to store large amounts of energy suffer from short lifetimes and
generate large amounts of harmful waste during production531
Technologies capable of co-electrolysing
water and carbon dioxide to syngas and hydrocarbons are at an early stage of development TRL 2-4
119810119822120784 + 119815120784119822 rarr 119810119822 + 119815120784 + 119822120784
It is also important to note that all electrolysers require a large input of electrical energy which would have to
be from renewable sources if this technology is to relieve its dependence on fossil fuels The major cost
associated with solid oxide electrolysis cells (SOEC) comes from the electricity required to operate them and
the feedstock while the cost of the electrolyser material makes up a smaller proportion of the total cost39
If
SOECs were designed to utilise wind and solar energy (PVssemiconductors) to generate the electricity they
require their operating costs would decrease significantly However this also decreases the number of
countries that could host electrolysers as their operation is again dependent on solar and wind energy It
would also be advantageous to incorporate a Fischer-Tropsch process that is capable of generating synthetic
hydrocarbons from the resulting syngas that can be used in the existing infrastructure3985
Syngas can be used to generate simple intermediate compounds that can be used as feedstock for more
complicated chemicals such as fertilisers pharmaceuticals plastics and synthetic liquid fuels Methanol is an
example of a simple molecule that can be made from syngas The dehydration of methanol can be used to
generate the cleaner fuel dimethyl ether which is being considered as a future energy source40
The most
common feedstocks for the production of hydrocarbon fuels are fossil fuels and biomass However it is hoped
that sustainable feedstocks such as carbon dioxide and water can be used to generate syngas which can be
converted into hydrocarbon fuels through Fischer-Tropsch synthesis39
Illustrations
Figure 37 A schematic diagram of water electrolysis being conducted in an alkaline electrolyser (left) and a polymer electrolyte
membrane electrolyser cell (right) to produce hydrogen and oxygen from water and DC electricity This figure was originally
produced by Carmo et al 20138
49
Figure 38 A schematic diagram of water electrolysis being conducted in a solid oxide electrolysis cell that produces hydrogen and
oxygen from water and DC electricity the reactions that occur at the electrodes are also shown This figure was adapted
from Meng Ni et al 20085
Explanations
Alkaline water electrolysis has been a mature technology for over 100 years (there were over 400 units in
operation by 1902) They have high efficiencies (47-82) and long lifetimes (15 years)1186
A recent
publication by Ursuacutea et al 2012 compiled a list of the main manufacturers of alkaline water electrolysers which
is shown in Table 3211
A number of advancements have been made regarding alkaline electrolysers over the last few years which
have focused on improving their efficiency to reduce operating costs and have increased the operating
current densities11
Other advancements include
Minimising the space between the electrodes to reduce the ohmic losses and allow the cell to operate at
current densities
Developing new materials to replace older diaphragms which exhibit higher stability and are better at
facilitating ion transport
Developing high-temperature (ca 150 oC) alkaline water electrolysers to increase the electrolyte
conductivity and promote the kinetics of the electrochemical reactions at the electrodesrsquo surface
Developing new electrocatalytic materials to reduce the electrode over-potentials this present a particular
difficulty for the anode because the oxidation half-reaction is most demanding
Alkaline electrolysers (Figure 3 left) consist of two electrodes that are separated by a gas-tight diaphragm
submersed in an electrolyte solution containing a high concentration of potassium hydroxide (20-30 wt) It
should be noted that electrolytes such as sodium hydroxide and sodium chloride can also be used in some
systems and they usually operate between 40-90 oC
11 Water is reduced at the cathode to generate hydrogen
gas and hydroxide ions (OH-) which diffuse through the diaphragm to the anode where they recombine to
generate oxygen and water811
The hydrogen and oxygen produced by alkaline electrolysers have purities
gt99
In PEM electrolysers (Figure 3 right) the electrolyte is constructed from a polymeric membrane with a cross-
linked solid structure permitting a compact system with greater structural stability (able to operate at higher
temperatures and pressures)8 The electrodes used in PEM electrolysers are usually constructed from noble
metals such as platinum and iridium which limits the scope of this technology as noble metals are of limited
abundance and expensive The unit consisting of the electrodes and polymer membrane is submersed in
water Water oxidation occurs at the anode where oxygen is formed and protons are transferred through the
50
polymer membrane to the cathode where they are reduced to hydrogen PEM electrolysers are able to
produce hydrogen and oxygen of even higher purity than alkaline electrolysers at ca 9999
It should be noted that the materials needed for the electrolyte and electrodes have to be cheap and easy to
manufacture on a large scale5 Water in the gas phase diffuses into the porous cathode where it dissociates
into hydrogen and oxygen at reaction sites81
At this point the hydrogen diffuses out of the cathode and is
collected The oxygen ions are transported through the electrolyte solution to the porous anode where they
are oxidised to oxygen and collected this process is demonstrated in Figure 35 The material chosen for the
cathode has to be able to support the diffusion of steam the reduction of steam and the diffusion of hydrogen
These requirements limit the number of suitable materials that can be used to noble metals such as platinum
and gold and non-precious metals such as copper and nickel However like the artificial photosynthetic
systems previously discussed the use of noble metals is unfavourable due to their rarity and high costs The
anode has to be chemically stable under similar conditions to the cathode which means that noble metals are
again candidate materials along with electronically-conducting mixed oxides5
Electrolyte This must be a chemically stable dense gas-tight material with good ionic conductivity and
low electronic conduction The electrolyte has to be stable enough to withstand the high temperatures
associated with the chemical reactions taking place It has to be gas-tight to limit the recombination of
protons and O- to hydrogen and oxygen respectively The electrolyte should also be as thin as possible so
as to minimise the ohmic overpotential5
Electrodes It should be noted that the following properties are the same for both the anode and cathode
The electrodes have to be porous enough to allow the transportation of hydrogen and oxygen and need to
have a similar thermal expansion coefficient to the electrolyte so as to limit the amount of mechanical
stress the components exert on each other They must also be chemically stable in highly
oxidisingreducing environments and high temperatures5
To ensure that the SOEC is operating at its maximum efficiency a number of parameters need to be
quantified this is often done through modelling the system Some of the parameters measured include the
composition of the cathode inlet gas cathode flow rate and cell temperature39
When generating syngas in a
SOEC the carbon dioxide is fed into the cathode side of the device where the hydrogen is generated
51
Table 32 The main manufacturers of alkaline and polymer electrolyte membrane electrolysers with the performance data for each device This table was originally constructed by Ursua et al 201211
Manufacturer
Technology
(configuration)
Production
(Nm3h)
Rated Power
(kW)b
Energy
Consumption
(kWhNm3)c
Efficiency
()d
Maximum
Pressure
H2 purity
(vol)
Location
AccaGen Alkaline (monopolar) 1-100 67-487 6-487 528-727 10 999 Switzerland
Avalance Alkaline (bipolar) 04-36 2-25 543-5 652-708 448 na USA
Claind Alkaline (bipolar) 05-30 na na na 15 997 Italy
ELT Alkaline (bipolar) 3-330 138-1518 46-43 769-823 1 998-999 Germany
ELT Alkaline (bipolar) 100-760 465-3534 465-43 761-823 30 993-998 Germany
Erredue PEM (bipolar) 06-213 36-108 6-51 59-698 25-4 993-998 Italy
Giner Alkaline (bipolar) 37 20 54 655 85 na USA
Hydrogen Technologies Alkaline (bipolar) 10-500 43-2150 43 823 1 999 Norway
Hydrogenics PEM (bipolar) 10-60 54-312 54-52 655-681 10 999 Canada
Hydrogenics Alkaline (bipolar) 1 72 72 492 79 9999 Canada
H2 Logic Alkaline (bipolar) 066-4262 36-213 545-5 649-708 4 993-998 Denmark
Idroenergy Alkaline (bipolar) 04-80 3-377 75-471 472-752 18-8 995 Italy
Industrie Haute Technology Alkaline (bipolar) 110-760 5115-3534 465-43 761-823 32 998-999 Switzerland
Linde Alkaline (bipolar) 5-250 na na na 25 999 Germany
PIEL division of ILT Technology Alkaline (bipolar) 04-16 28-80 7-5 506-708 18-8 995 Italy
Proton OnSite PEM (bipolar) 0265-30 18-174 73-58 485-61 138-15 99999 USA
Sagim Alkaline (bipolar) 1-5 5-25 5 708 10 999 France
Teledyne Energy Systems Alkaline (bipolar) 28-56 na na na 10 99999 USA
Tredwell Corporation PEM (bipolar) 12-102 na na na 75 na USA
52
332 Current status review of the state of the art
This section will focus on the advancements that have recently been made in regards to SOECs Much of the
research being conducted on SOECs is focused on increasing the efficiency and stability of the electrolyte and
electrodes by changing the temperature the SOECs operate at gas mixtures and the materials the cells are
constructed from
The most common electrolyte material used in SOECs yttria-stabilised zircona (YSZ) due to it having a high
thermal stability high oxygen ion conductivity and low cost To generate YSZ zirconia (ZrO2) can be doped
with compounds such as Y2O3 and Yb2O3 to improve the stability and conductivity Sc2O3 can also be used to
generate scandia-stabilised zirconia (ScSZ) Other co-dopants such as TiO2 and Al2O3 can be added to
further enhance the stability587
Scandium stabilised zirconia (ScSZ) has a higher conductivity than YSZ but
is not as widely used due to the high costs associated with it It should also be noted that the dopant
concentration has to be of a specific amount in order to ensure the conductivity is at its maximum It has been
shown that different dopant concentrations change the lattice structure of the ZrO2 over time which leads to
the decrease in conductivity5 The dopant chosen for the SOEC is also dependent on the temperature the cell
will have to operate at as the dopant will change the conductivity of the electrolyte at different temperatures
Researchers recently investigated the effect temperature (550 oC ndash 750
oC) had on the performance of SOEC
cells with the following layout a Ni-YSZ support layer (680 microm) a Ni-ScSZ cathode-active layer (15 microm) a
ScSZ electrolyte layer (20 microm) and a LSM-ScSZ anode layer (15 microm) The performance of the cell was
observed to decrease with decreasing temperature when the same gas composition was used (143 CO
286 H2O and 571 Argon) As the temperature decreased the ionic conductivity of the electrolyte layer
decreased The mass transfer was the rate-determining step for the electrodes at temperatures lt750 oC
Methane was only detected in the gas products when the input gas composition was the same as above the
cell temperature was lt700 oC and the operating voltage was gt 2 V
81 (TRL 3)
Electrolyte materials such as ceria- and LaGaO3-based electrolytes are showing promise at intermediate
temperatures when they are doped with other compounds that increase their ionic conductivity79
Recently
researchers developed SOEC capable of steam and carbon dioxide co-electrolysis The cell was constructed
from Ni-YSZ (nickel-yttria-stabilized zirconia) solid oxide cell with a bi-layered ScSZGDC electrolyte structure
and a LSCF (lanthanum strontium cobalt ferrite) oxygen electrode When the device was operated at 800 oC
the cell exhibited a high electrolysis current density of about 22 A cm2 and 19 Acm
2 in steam and carbon
dioxide electrolysis respectively The structural integrity of the cell was checked after the experiment and no
cracking or delamination of the electrolyte or the electrolyteelectrode was observed88
(TRL 4)
Researchers were recently able to directly synthesise methane by co-electrolysing carbon dioxide and water
to form carbon monoxide and hydrogen then conducting Fischer-Tropsch synthesis in tubular solid oxide
electrolysis cells7 As previously discussed the reduction of water in SOECs requires very high temperatures
(ca 800 oC) however with the Fischer-Tropsch process lower temperatures (ca 250
oC) are required Using
the experimental setup shown in Figure 3 researchers were able to achieve a methane yield of 1184
which means that 41 of carbon dioxide is converted to methane over the course of the 24-hour test7 The
equipment consists of a SOEC tube with a hole running through its length while the wall of the tube consists
of three layers that are structured in a similar fashion to that shown in Figure 3 it consists of an anode an
electrolyte and a cathode The first section of the SOEC tube is heated to 800 oC to allow syngas to be
generated after which the tube cools over a gradient to 250 oC to allow methane production to take place
(TRL 4)
53
Table 33 The advantages and disadvantages of alkaline polymer electrolyte and solid oxide electrolysis cell electrolysers This table
was originally constructed by Carmo et al 20138
Alkaline Electrolysis PEM Electrolysis SOEC Electrolysis
Advantages
Well-established technology High current densities Efficiency up to 100
Non-noble metal catalysts High voltage efficiency Efficiency gt 100
Long-term stability Good partial load range Non-noble metal catalysts
Relative low cost Rapid response system High pressure operation
Stacks in the megawatt range Compact system design
Cost effective High gas purity
Dynamic operation
Disadvantages
Low current densities High cost of components Laboratory stage
Crossover of gases Corrosive environment Bulky system design
Low partial load range Low durability Low durability
Low dynamics Stacks below megawatt range Little costing information
Corrosive electrolyte
Figure 39 A schematic diagram of co-electrolysis and the Fischer-Tropsch process being conducted in a tubular solid oxide
electrolyser that is able to produce CH4 This figure was originally generated by Chen et al 20147
333 Patents
The cell was composed of separate anode and cathode chambers separated by a membrane that allows the
transport of sodium ions (Na+) the anode and cathode chambers are in contact with water Oxygen is
collected in the anode chamber and hydrogen is collected in the cathode chamber following which hydrogen
and carbon dioxide are reacted together to generate syngas and oxygen as by-products that need to be
separated The electrode materials were described as being ceramic that could be doped with a catalyst
material such as cobalt cerium europium or cadmium combinations of these elements were also permitted89
(TRL 3)
A patent was filed in 2011 detailing a design for SOEC that could co-electrolyse steam and carbon dioxide to
produce syngas The cell consisted of a cathode composed of nickel-zirconia an anode consisting of
strontium doped lanthanum manganite and the electrolyte between the two electrodes was composed of
yttria-stabilised zirconia the whole cell was designed to operate between 800-1000 oC The authors stated
that the electrical power to run the device would be sourced from nuclear power however it should also be
possible to run this device off solar energy This device operated with the carbon dioxide being fed into the
cathode section where the hydrogen is generated90
(TRL 4)
54
A patent was filed in 2013 detailing a modified anodeelectrolyte structure for a solid oxide electrochemical
cell where the role of the anode is to react with fuel (steamhydrocarbons) The cathode (when in SOEC
mode) consisted of a backbone of electronically conductive perovskite oxides selected from the group
consisting of niobium-doped strontium titanate vanadium-doped strontium titanate and tantalum-doped
strontium titanate mixtures were also permitted The electrolyte material consisted of a scandia and yttria-
stabilised zirconium oxide91
(TRL 2-3)
334 Future development main challenges
Technologies that are capable of electrolysing water cover a variety of TRLs wherein alkaline and PEM
electrolysers used to generate hydrogen by the water-splitting reaction have TRLs 7-8 as they have been
commercialised can be purchased and can produce power at the low megawatt scale However they are
currently not a viable option to generate power at the megawatt scale Newer SOEC technologies currently
being developed have lower TRLs (3-5) but are showing great promise in that their efficiencies are high and
they are cheap to produce
Technologies capable of co-electrolysing water and carbon dioxide to syngas are at an early stage of
development - TRLs 2-4 Research is still focused on studying how cell conditions can be manipulated to
optimise the production of syngas and hydrocarbons Research is also focused on improving the long-term
stability of the electrolytes and electrodes used in SOECs by investigating new materials and cell designs that
are cheap and easy to construct It will also be necessary to conduct duration experiments In terms of their
commercial viability they are far behind PVs at roughly the same stage as PEC technologies and ahead of
synthetic biology systems
SOECs could prove to be an efficient method by which electrical energy generated from renewable sources
(wind and solar) could be stored in the form of chemical bonds To date it has been proven that syngas can
be generated from SOECs and that methane can also be generated within the same system through a
Fischer-Tropsch process More research is needed that aims to improve the efficiency by which methanol can
be generated and to determine whether more complex hydrocarbons can be synthesised
The success of this technology is likely to be dependent on how well systems that generate electricity from
renewable sources can be integrated within it It has been suggested that nuclear wind and solar power
stations could be used to provide the electrical power required This would help to lower the cost of this
technology as sourcing the electricity needed is one of the major costs It should be noted that one of the
most commonly cited advantages of this technique over solar and wind power is that it is not site-specific
However if solar and wind power were to be used to generate the electricity needed for this technology then
it becomes a site-specific technology again This is also a problem for PEC-cell-based technologies
34 Summary
The aim of this brief literature review was to highlight the advancements that have been made across the main
technologies within artificial photosynthesis discuss some of the most recent technological solutions that have
been developed in these areas and identify the main challenges that need to be addressed for each
technology before they can be commercialised
Synthetic biology amp hybrid systems
Synthetic biology amp hybrid artificial photosynthetic systems are currently capable of producing small amounts
of fuel molecules such as hydrogen and simple hydrocarbons The majority of the technologies in this
category are at the research and development stage (TRL 1-4) To date there are no large scale plans to
produce solar fuels at a commercial level using this technology It should be noted that synthetic biology amp
hybrid systems are currently used to produce fine chemicals at the commercial level but these are not needed
55
in the large quantities in which solar fuels are required It is currently too early to comment on the long-term
commercial viability of this technological pathway however the research in this area is progressing quickly
and as our fundamental understanding of biological systems increases progression is promising It should be
noted that these systems are becoming efficient enough to produce hydrogen at a rate that is comparable to
that which occurs in natural photosynthesis on a small laboratory scale
Photoelectrocatalysis of water (water splitting)
PVssemiconductors are the most advanced technology discussed in this report as they have been
commercialised and are able to generate electricity on a MW scale at facilities such as the Solar Star Power
Station and the Topaz Solar Farm31
PVssemiconductors are used in PEC technologies where they are
incorporated into the cell design and act as light absorbers Instead of the energy gained from light absorption
being used to generate electricity directly it is used to generate fuel molecules such as hydrogen from the
water-splitting reaction The hydrogen generated from this process can then be stored and used at a later time
to provide energy This is useful because PVs are only able to generate power intermittently during daylight
hours There are many examples of photoelectrocatalysis being carried out by PECs as well as suspensions
of photoactive nanoparticles and the majority of the technologies have a TRL 2-4 However it should be noted
that PVsemiconductor technologies that generate electrical power have TRL 8-9 The main challenges facing
this technology involve developing materials that have high STH efficiencies are cheap to manufacture and
are stable for long periods of time Calculations have been performed to determine the efficiencies associated
with multiple reactor plant designs These have shown that it is theoretically possible to generate large
quantities of hydrogen however that it could cost trillions to generate a significant amount of hydrogen with
current technology
Co-electrolysis
Water electrolysers such as alkaline and PEM electrolysers are considered mature technologies that have
been commercialised and have TRLs 7-8 They can be purchased and can produce power at the low
megawatt scale However they are currently not a viable option to generate power at the megawatt scale
Newer SOEC technologies that are currently being developed have lower TRLs 3-5 but are showing great
promise in that their efficiencies are high and they are cheap to produce Technologies that are capable of
generating syngas and some organic products by a Fischer-Tropsch process are in the research and
development stage (TRL 3-4) Research is currently focused on determining how SOEC conditions can be
manipulated to increase efficiency as well as identifying more stable durable and efficient compounds to
incorporate into the cell design The incorporation of SOECs into large scale solar and wind farms could prove
to be an efficient method by which electrical energy can be stored as chemical energy
The technologies discussed above show great potential in being able to convert solar energy into solar fuels
They are still in the early research phase but all technologies made significant improvements in efficiencies
lifetimes and the number of products they can produce other than hydrogen It is likely that PVs will be used to
absorb solar energy to generate electricity for SOECs or forms part of a PEC cell that generates fuel
molecules It should be noted that wind power could be used to provide the electricity needed for SOECs to
operate which would allow these systems to be used outside of desert regions Biological systems currently
look to be less suitable for producing large quantities of fuel molecules partly due to their early research stage
but may prove to be useful in generating highly complicated molecules once the understanding of protein
engineering has increased
All of these technologies seek to improve device lifetimes increase efficiency lower manufacturing costs and
increase the scope of synthetic fuels that can be produced Switching to a hydrogen economy will require
large and expensive infrastructure changes Using hydrogen to generate more complex fuel molecules will
require more research however ultimately fewer infrastructure changes
57
4 Mapping research actors
41 Main academic actors in Europe
In Europe research on AP is conducted by individual research groups or in research networks or consortia
Most of the research groups are located in Germany the Netherlands and Sweden The largest country-based
networks are also in Sweden and in the UK Most of Germanyrsquos research groups are part of the pan-European
AP network AMPEA The number of research groups has increased substantially since the 1990s when the
field became more prominent coupling with the (exponential) rise of publications in AP3
411 Main research networkscommunities
In this section we describe the main research networkscommunities on artificial photosynthesis in Europe
Under networks we indicate co-operations with multiple universities research organisations and companies
Instead of focusing strictly on major integrated research on specific AP topics the networks mostly have a
broad research and collaboration focus Larger joint programmes exist but are more focused on various key
priorities in Europe for different research areas such as AMPEA (Advanced Materials and Processes for
Energy Application) which is one of the joint programmes of EERA (European Energy Research Alliance) of
which artificial photosynthesis is one of the three identified applications The first national research network
dedicated to artificial photosynthesis was the Swedish Consortium for Artificial Photosynthesis (CAP)
following which a number of other national and pan-European networks emerged in the past few years
Research networks and communities play an important role in facilitating collaboration across borders and
among different research groups The development of AP processes needs expertise from molecular biology
biophysics and biochemistry to organometallic and physical chemistry Research networks provide the
platform for researchers and research teams from those diverse disciplines to conduct research together to
create synergistic interactions between biologists biochemists biophysicists and physical chemists all
focusing on questions relevant for AP and solar fuels This need for research coordination is reflected by the
fact that the Swedish Consortium for AP was a bottom-up initiative by university-based scientists4
Furthermore networks are effective for promoting AP research and raising public awareness and knowledge
about AP5
Networks and consortia with industrial members also play an important role with respect to the goal of turning
successfully developed AP processes into a commercially viable product Research and innovation in
materials and processes of AP can be backed up by private innovation and investments Feedback on the
applicability of research outputs can be incorporated and shape further research efforts and application
possibilities in the business sector can be discovered
The advantages and synergy effects of network membership for research groups are reflected in the fact that
more than 50 of European research groups are part of a research network in Europe The consortia vary in
their membership and their funding sizes whereas about 400 researchers are affiliated with the pan-European
consortium AMPEA the Swedish CAP unites about 80 scientists Furthermore it is apparent that only AMPEA
is a truly pan-European consortium member research groups come from various European countries such as
Austria France Czech Republic Germany Italy the Netherlands Norway Spain Sweden Switzerland and
3 V Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in
ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press) conducted a bibliometric analysis using key words related to the field of artificial photosynthesis showing that only a few papers were published before the 1990s reaching more than 900 publications in 2014
4 httpwwwsolarfuelse
5 httpsolarfuelsnetworkcomoutreach
58
the UK Most of the other consortia discussed below are based in a specific country which is reflected in their
affiliations among research groups
EU - AMPEA
The European Energy Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials
amp Processes for Energy Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging
Technologies and artificial photosynthesis became the first energy research subfield to be organised within
AMPEA The goal of this joint programme which was launched at the end of 2011 is to set up a thorough and
systematic programme of directed research which by 2020 will have advanced to a point where commercially
viable artificial photosynthetic devices will be under development in partnership with the industry Its goal to
boost research on a pan-European basis is reflected in the fact that to date more than 40 European scientific
institutions participate Many institutes in different Member States are associated with AMPEA (31 full
members for example CEA DIFFER TU Delft JKU Max Planck Institute)6 The research efforts of the
AMPEA participants aim at advancing all of the three identified pathways of artificial photosynthesis Due to
the low availability of efficient molecular catalysts based on earth-abundant elements the search for those
elements and the development of such catalysts constitute the early research focus
Italy ndash SOLAR-CHEM
In 2009 the universities of Bologna Ferrara and Messina founded SOLAR-CHEM the Italian inter-university
centre for the chemical conversion of solar energy7 Later on other universities in Italy also joined SOLAR-
CHEM The research efforts of the centre aim to foster research in solar fuels through a multidisciplinary
approach and coordination activities eg through the organisation of dedicated events and through short-term
exchanges of staff in the network
Netherlands ndash BioSolar Cells
The Dutch BioSolar Cells public-private partnership was established in 2010 BioSolar Cells is a cooperation
of 10 knowledge institutions such as Leiden University Delft University of Technology and the University
of Twente8 as well as 45 private industries
9 The programme is funded by FOMALWNWO the Dutch
ministry of Economic Affairs Agriculture and Innovation many companies and a number of Dutch universities
and research organisations The BioSolar Cells programme has three themes artificial photosynthesis
photosynthesis in cellular systems and photosynthesis in plants These three research themes are
underpinned by a fourth theme education and societal debate where educational modules are developed to
equip and inspire future researchers policy makers and industrialists and where the societal consequences
of new solar-to-fuel conversion technologies are debated10
Sweden - CAP
Founded in 1994 the Swedish Consortium for Artificial Photosynthesis carries out integrated basic
research with the goal to produce applicable outcomes such as fuel from solar energy and water Their
projects integrate two topics artificial photosynthesis in man-made systems to make hydrogen from sun and
water and photo-biological fuel production in living organisms They focus on photoelectrocatalysis as the
technology pathway yet are also building on their research on the principles of natural photosynthesis for
energy production A unique component in the consortium is hence the synergistic interactions between
biologists biochemists biophysicists and physical chemists all focusing on questions relevant for solar
fuels11
The academic partners come from Uppsala University Lund University and the KTH Royal
Institute of Technology in Stockholm
6 httpwwweera-seteueera-joint-programmes-jpsadvanced-materials-and-processes-for-energy-application-ampea
7 httpswwwsocchimitsitesdefaultfileschimindpdf2012_6_88_capdf
8 httpwwwbiosolarcellsnlover-biosolar-cellsnew_page_1html
9 httpwwwbiosolarcellsnlover-biosolar-cellsbedrijvenhtml
10 httpwwwbiosolarcellsnlonderzoek
11 httpwwwsolarfuelsesolar-fuels
59
UK ndash SolarCAP
The SolarCAP Consortium for Artificial Photosynthesis is a consortium of four UK academic research groups
funded by the Engineering and Physical Sciences Research Council The groups based in the Universities
of East Anglia Manchester Nottingham and York12
are specifically exploring the solar conversion of
carbon dioxide to carbon monoxide in tandem with the conversion of methane or alkanes to useful oxygen-
containing products such as alcohols They are exploring the second technological pathway of
photoelectrocatalysis
UK ndash Solar Fuels Network
Solar Fuels Network brings together academic and industrial researchers in solar fuels and artificial
photosynthesis It aims to develop an effective community of solar fuels researchers from both academia and
industry to raise the profile of the UK solar fuels research community nationally and internationally Through
this it aims to promote collaboration and co-operation with other research disciplines industry and
international solar fuels programmes and to contribute towards the development of a UK solar fuels
technology and policy roadmap The networkrsquos management team is based at Imperial College London and
is led by Prof James Durrant Partner organisations encompass the Royal Society of Chemistry the Energy
community of the Knowledge Transfer Network (KTN) the Solar Fuels Institute (SOFI) and the Foreign and
Commonwealth Officersquos Science and Innovation Network13
In other countries across Europe national initiatives have emerged in the last few years and more are
expected to in the future For example the Photoelectrochemistry Competence Center (PECHouse and
PECHouse2)14
under coordination of the Ecole Polytechnique Federale de Lausanne (prof Michael Graumltzel)
has been created in Switzerland while in France artificial photosynthesis is being researched by laboratories
of excellence (LabEx Arcane15
and LabEx Charmatt16
)
412 Main research groups (with link to network if any)
A list of the main research groups in Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire Artificial
Photosynthesis community Taking that into account the numbers presented below may provide an indication
of the AP research sector as a whole
Table 41 Number of research groups and research institutions in European countries
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Austria 1 1 15
Belgium 1 1 -
Czech Republic 1 1 -
Denmark 3 2 -
Finland 1 1 6
France 5 3 14
Germany 31 17 16
Ireland 1 1 7
Italy 5 5 29
Netherlands 28 9 18
Norway 1 1 -
12
httpwwwsolarcaporgukresearchgroupsasp 13
httpsolarfuelsnetworkcommembership 14
httppechouseepflchpage-32075html 15
httpswwwlabex-arcanefrencontentlaboratoires-excellence-arcane 16
httpwwwcharmmmatfrindexphp
60
Country Number of research
groups
Number of research
institutions
Average size of a research
group
Spain 4 4 11
Sweden 13 5 17
Switzerland 5 5 10
UK 13 9 10
Total 113 65 15
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 66 main research institutions and universities working on artificial photosynthesis in Europe
Those research institutions contain 113 individual research groups with an average size of about 15
people17
The sizes of research groups can vary widely from for example 80 members of a research group at
Imperial College London to only two persons in the research group of Klaus-Dieter Weltmann at the Leibniz
Institute for Plasma Science and Technology The country with both the highest number of involved institutions
and research groups is Germany where 32 individual research groups in 17 research institutions are active
Germany is followed by the Netherlands with nine institutions and 28 research groups and by Sweden with
five institutions and 13 research groups Almost half (47) of the research groups focus on the second
pathway ie photoelectrocatalysis whereas 36 research the first pathway ie the usage of synthetic
biology and hybrid systems to produce fuel molecules and about 17 follow the third pathway in their
research which is co-electrolysis A bulk of the research in most countries is done on the second pathway
except for in Sweden and Finland which seem to specialize in exploring the first pathway Table 42 provides
an overview of some of the key statistics the number of research groups and research institutions in AP per
country and the number of research groups focusing on each of the three technological pathways
respectively
Table 42 Number of research groups per research area (technology pathway)
Country Total Synthetic biology
amp hybrid systems
Photoelectrocatalysis Co-electrolysis
Austria 1 1 1 0
Belgium 1 1 1 0
Czech Republic 1 0 1 0
Denmark 3 0 2 2
Finland 1 1 0 0
France 5 2 5 0
Germany 31 14 15 9
Ireland 1 1 1 0
Italy 5 0 5 0
Netherlands 28 12 17 9
Norway 1 0 1 0
Spain 4 2 3 1
Sweden 13 10 7 0
Switzerland 5 1 5 3
UK 13 8 5 1
Total 113 53 69 25
Source Ecorys
17
The average group size is derived from survey responses and available information on the websites of the groups
61
In the following section our findings have been illustrated by presenting some of the main research institutions
and their research groups
Germany - Helmholz Zentrum Berlin
The Institute for Solar Fuels of the HZB is led by Prof Roel van de Krol The institute pursues a strategy to generate
hydrogen via the second technology pathway they combine the energy conversion of light into electrical energy via
photonic stimulation of the semiconductor directly with the catalytic procedures on the electrolyte-electrode-interface for
the conversion into storable chemical energy (hydrogen) The generated hydrogen can then be stored by means of
already known methods (compressed gas liquid-H2 metal hydride conversion to methanol) Their approach combines
research and insights from photo-physics surface- and material chemistry photoelectrochemistry interface- and
surface sciences as well as system alignment18
Therefore they collaborate closely with the University of Messina in
Italy and the Leiden University in the Netherlands Moreover the HZB is also part of the European research network
AMPEA
Germany ndash Max Planck Institute for Chemical Energy
The Department of Biophysical Chemistry at the Max Planck Institute for Chemical Energy focus on the water-oxidizing
enzyme of oxygenic photosynthesis and hydrogenases Their research uses a variety of different physical techniques
to gain insight into enzymatic processes such as into photosynthetic water splitting and (bio)hydrogen production
which can be used for biomimetic chemistry ie to develop catalytic systems in energy research19
They hence focus
on the first and second technology pathways The Max Planck Institute for Chemical Energy also contributes to the
European research network AMPEA
The Netherlands - The Dutch Institute for Fundamental Energy Research
Part of the Netherlands Organisation for Scientific Research (NWO) the DIFFER institute has since its initiation in 2012
grown to an activity of about 65 Meuroyear (about 75 fte) all directed at the production of chemicalsfuels from electrons
and photons In particular as part of its solar fuels research DIFFER investigates the splitting of water into hydrogen
and oxygen using electricity and the reduction of carbon dioxide to carbon monoxide As they are located at TUe
campus in Eindhoven they can easily collaborate and share knowledge with universities universities of applied
sciences and industry The DIFFER institute also contributes to AMPEA
Sweden ndash Uppsala University
Various research teams at Uppsala University cover all three relevant technology pathways for artificial
photosynthesis20
Moreover in 2006 the Swedish Consortium for Artificial Photosynthesis (CAP) founded in 1994 by
three researchers from Uppsala University and one researcher from the University of Stockholm created a new
scientific environment at the Aringngstroumlm laboratory at Uppsala University becoming the base for this consortium
Switzerland ndash ETH Zurich
The Professorship of Renewable Energy Carriers21
performs RampD projects in emerging fields of renewable energy
engineering operates state-of-the-art experimental laboratories offers advanced courses in fundamentalapplied
thermal sciences and produces qualified scientists and engineers with expertise in renewable energy technologies
Regarding solar fuels they focus on solar splitting of H2O and CO2 via thermochemical Redox cycles which
corresponds to the third technology pathway of artificial photosynthesis They are partners in several EU projects
concerning solar-driven hydrogen production such as SOLARJET ndash Solar Production of Jet Fuel from H2O and CO2
and HYCYCLES ndash Solar Water-Splitting Thermochemical Cycle22
18
httpswwwhelmholtz-berlindeforschungoeeesolare-brennstoffeindex_enhtml 19
httpwwwcecmpgderesearchbiophysical-chemistryoverviewhtmlL=1 20
httpwwwkemiuuseresearchmolecular-biomimeticphotosynthesis 21
httpwwwprecethzch 22
httpwwwprecethzchresearchsolar-fuelshtml
62
UK ndash Imperial College London
The research of various research teams of the Imperial College London encompasses the first and second technology
pathways It ranges from research on the oxidising enzyme Photosystem II which has become the focus of attention
because cheap water-splitting catalysts are urgently needed in the energy sector to the development of
photoelectrodes and nanoparticles for solar-driven fuel synthesis based on water splitting of water into hydrogen and
oxygen Collaborations across the Imperial College London are complemented with co-operations across the UK as
part of the UK Solar Fuels Network with the Swiss Federal Institute of Technology in Lausanne (EPFL) UCL and
Cambridge University
The density of research group per country in Europe is presented schematically in Figure 41
Figure 41 Research groups in Artificial Photosynthesis in Europe
Source Ecorys
42 Main academic actors outside Europe
Also outside of Europe research on AP is conducted by individual research groups or in research networks or
consortia Most of the research groups and networks are located in the US and in Japan Whereas US-based
networks sporadically have ties to European research groups the Japanese consortia have exclusively
Japanese members both academic and industrial
421 Main research networkscommunities
Outside of Europe the main networks can be found in the US and in Japan The biggest network is the US
network JCAP (Joint Center for Artificial Photosynthesis) with more than 190 persons linked to the
programme and a budget of $122 million for five years Next in line is the Japanese ARPChem which has
roughly the same budget available for a time span of 10 years
63
Japan ndash ARPChem
The Japanese Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology jointly launched the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem) in November 2012 The aim is to bundle efforts for the next
decade to develop innovative catalysts and other materials that could be used for manufacturing fundamental
chemical substances from water and carbon dioxide by making use of solar power Such substances can be
used as raw materials of plastics synthetic fibres synthetic rubber solvents and other products and are
applicable in all areas of peoples everyday lives The expected budget for the coming decade between 2012
and 2021 amounts to 15 billion yen (euro 122 million)23
The utilisation of catalyst technology requires long-term
involvement and entails high risks in development but is expected to have a huge impact on Japans
economy and society The aim is to achieve independence from fossil resources used as raw materials for
chemical substances while overcoming resource and environmental challenges The consortium consists of
partners from academia industry and the government seven universities amongst them the University of
Tokyo the Tokyo University of Science and the Kyoto University companies such as Mitsubishi
Chemicals Mitsui Chemicals Fuji Films and TOTO and governmental research organizations such as the
National Institute of Advanced Industrial Science and Technology (AIST)
Japan ndash All Nippon Artificial Photosynthesis Project for Living Earth (AnApple)
The All Nippon Artificial Photosynthesis Project for Living Earth (AnApple) is one of the Scientific
Researches on Innovative Areas receiving strong financial support from the Ministry of Education Culture
Sports Science and Technology It was set up in 2012 as a five-year national project Although it is not a
consortium in a narrow sense its scope and research impact are substantial as more than 40 Japanese
leading scientific groups are part of this project It is led by Prof Haruo Inoue from the Tokyo Metropolitan
University further academic partners are amongst others the Tokyo University of Science the Tokyo
Institute of Technology Ibaraki University Ritsumeikan University and Hokkaido University
South Korea ndash KCAP
The Korean Centre for Artificial Photosynthesis (KCAP) was launched at Sogang University in 200924
set up
as a ten-year programme with 50 billion won (about euro40 million)25
It aims to secure a wide range of
fundamental knowledge necessary materials and device fabrication for the implementation of artificial
photosynthesis ie generating liquid fuel and oxygen from water and carbon dioxide using solar energy
through collaborative research with a number of research organisations and companies The Korean partners
comprise 14 professors from 8 universities including Sogang University Yonsei University and the Ulsan
National Institute of Science and Technology and one industry partner Pohang Steel Company26
Foreign academic partners are the Lawrence Berkeley National Laboratory California Institute of
Technology and University of California Berkeley The Centre has ties to other AP networks such as SOFI
and JCAP
US ndash JCAP
In 2010 the Department of Energy created the Energy Innovation Hubs and among them a Joint Centre for
Artificial Photosynthesis (JCAP) was established between the California Institute of Technology and the
Lawrence Berkeley National Laboratory in California27
JCAP draws on the expertise and capabilities of key
collaborators from the University of California (UCI and UCSD) and the SLAC National Accelerator Laboratory
operated by Stanford University The initial funds in 2010 amounted to $122 million JCAP is the largest
artificial photosynthesis network in the US with more than 190 persons linked to the programme The research
foci encompass electro-catalysis photo-catalysis and light capture materials integration and numerical
23
httpwwwmetigojpenglishpress20121128_02html 24
httpwwwk-caporkrenginfoindexhtmlsidx=1 25
httpwwwsogangackrnewsletternews2011_eng_1news12html 26
httpswwwicef-forumorgannual_2015speakersoctober8cs2appdfcs-2_20058_kyung_byung_yoonpdf 27
httpsolarfuelshuborgwho-we-areoverview
64
modelling test-bed prototyping and benchmarking The funds for the next five-year period (2016-2020)
amount to $75 million and are subject to congressional appropriation
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years Core members include the Northwestern University and
Uppsala University A process of exchanges is instituted which encompasses six different universities in four
countries Industry partners are ILampFS (India) Total (France) and Shell28
This list is not exhaustive and increasing interest in the field of artificial photosynthesis would certainly lead to
the launch of new national and international programmes
422 Main research groups (with link to network if any)
A list of the main research groups outside Europe has been established The list is not exhaustive and the
subsequent descriptive statistics are based on the list and do not necessarily describe the entire AP
community outside of Europe We are confident however that it provides an accurate indication about the AP
sector outside of Europe
Table 43 Number of research groups and research institutions in non-European countries
Country Number of research groups Number of research institutions Average size of a
research group
Australia 1 1 18
Brazil 1 1 5
Canada 1 1 -
China 12 5 13
Israel 1 1 6
Japan 16 15 15
Korea 4 4 16
Singapore 1 1 14
US 40 32 18
Total 77 61 5
Note The average size of a research group is calculated only for groups where the information on the size is available If no
information on size is available the research group was excluded from the calculation refers to the groups where no
information is available on the size of it
Source Ecorys
We identified 61 main research institutions or universities working on artificial photosynthesis outside of
Europe most of which are based in the US and in Japan Those research institutions contain 77 individual
research groups with an average group size of 8 people29
Yet the sizes of research groups can vary widely
from 26 members at the University of Tokyo to only two persons at Kobe University The country with both the
highest number of involved institutions and research groups is the US where 40 individual research groups in
32 research institutions are active Hence the US is a world leader in terms of research groups working on
AP Japan follows with 16 institutions and 15 research groups which lies below the numbers for Germany
and the Netherlands Almost 80 of the research groups (77) focus on the second pathway
(photoelectrocatalysis) whereas about 39 research the first pathway (synthetic biology amp hybrid
systems) The remaining 18 focus their activities on the third pathway (co-electrolysis) Table 44
28
httpwwwsolar-fuelsorgabout-sofi 29
The average group size is derived from survey responses For more information please refer to Annex I
65
provides an overview of some of the key statistics such as the number of AP research groups and institutions
per country and their respective focus on one of the three technology pathways
Table 44 Number of research groups per research area (technology pathway)
Country Technology
pathway
Total Synthetic biology
and hybrid systems
Photoelectrocatalysis Co-electrolysis
Australia 1 1 1 0
Brazil 1 0 1 0
Canada 1 0 1 1
China 12 4 6 2
Israel 1 1 0 1
Japan 16 7 15 1
Korea 4 0 4 0
Singapore 1 0 1 0
US 40 17 30 9
Total 77 30 59 14
Note a research group might focus on multiple technology pathways
Source Ecorys
In the following section our findings are illustrated by presenting some of the main research institutions and
their research groups
China ndash Dalian University of Technology
In 2011 the Dalian National Laboratory for Clean Energy (DNL) based at the Dalian Institute of Chemical Physics
(DICP) of the Chinese Academy of Sciences (CAS) was established It integrates research into clean energy and the
efficient use of fossil fuels to meet Chinas sustainable energy development strategy It is led by Li Can
Israel - Weizmann Institute of Science
To meet the challenge of providing clean sustainable energy the Weizmann Institute has established the Alternative
Sustainable Energy Initiative (AERI) The goal of this initiative is to create the conditions conducive to alternative
energy research and to identify promising avenues of research With the help of AERI the Weizmann institute hopes to
encourage its scientists to conduct basic research relevant to the future development of alternative sustainable energy
and to nourish the next generation of scientists in this field around the world in Israel and at the Weizmann Institute
The researchers at the Weizmann Institute of Science and at AERI preliminarily focus on the third pathway
Japan ndash University of Tokyo
The Domen Laboratory at the University of Tokyo is a research group focused on the second technological pathway
Their challenge is to find out novel photocatalysts that effectively work on water splitting under visible light by studying
different new materials
US ndash Arizona State University
The multidisciplinary team of the Center for Bio-inspired Solar Fuel Production of the Arizona State University aims to
design a complete system for solar water oxidation and hydrogen production Therefore they are focusing on five
specific subtasks (i) The total system analysis of the solar water-splitting device (ii) water oxidation (iii) fuel
production (iv) the artificial reaction center-antenna which relates to light collection and (v) the development of
functional nanostructured transparent electrode materials Their focus lies hence on the first and second AP technology
pathways
The density of research groups per country in the world is presented schematically in Figure 42 Please note
that in this figure (as opposed to Figure 41) we do not count each European country individually but
aggregate the numbers for all of Europe
66
Figure 42 Research groups active in the field of AP globally
Source Ecorys
43 Level of investment
In this section the level of investment is discussed in further detail The level of research investment in the EU
is based on the total budget of the projects whenever available In addition information is given on the time
period of the research projects
Information on the investment related to or funding of artificial photosynthesis research programmes and
projects at the national level is generally difficult to find especially for academic research groups Most budget
numbers found relate to the budget of the institution andor the (research) organisation in general and are not
linked to specific artificial photosynthesis programmes in particular unless the institute or research
programme is completely focused on artificial photosynthesis
Table 45 presents an overview of the investments made by a number of organisations
Table 45 Investments in the field of artificial photosynthesis
Country Organisation Budget size Period
Research investments in Europe
EU European Commission (FP7 and previous
funding programmes) euro 30 million 2005 - 2020
France CEA euro 43 billion 2014 covers not only AP
Germany
German Aerospace Centre (DLR) and the
Helmholtz Zentrum euro 4 billion
Annual budget covers
not only AP
Germany
Max Planck Institute for Chemical Energy
Conversion euro 17 billion 2015 covers not only AP
Germany
BMBF ldquoThe Next Generation of
Biotechnological Processesrdquo euro 42 million 2010 - present
Germany Government of Bavaria euro 50 million
2012-2016 covers not
only AP
Members of AMPEA AMPEA (EERA) euro 60 million 2010 - present
Netherlands Biosolar Cells euro 42 million 2010-present
Sweden Consortium for Artificial Photosynthesis euro 118 million 2013
UK SolarCAP and other initiatives in UK euro 92 million 2008-2013
67
Country Organisation Budget size Period
UK
University of East Anglia Cambridge and
Leeds euro 1 million 2013
Research investments outside Europe
China Dalian National Laboratory for Clean Energy euro 40 million Annual budget since
2011
Israel AERI euro 13 million 2014-2017
Japan ARPChem euro 122 million 2012 - 2021
Korea KCAP euro 385 million 2009 - 2019
UK US Plug-and-play photosynthesis euro 44 million 2014 - 2017
US JCAP euro 175 million 2010 - 2020
US SOFI euro 1 billion 2012 - 2022
Source Ecorys
431 Research investments in Europe
In Europe national researchers research groups and consortia are generally funded by European funds (such
as the ERC Grant from the European Commission) national governments businesses and universities In this
section special attention is paid to the EU FP7 projects These projects are mainly funded by European
contributions Further information is provided on AMPEA BioSolar Cells CAP SolarCap and some other AP
initiatives
Investments range between euro10 million for the national consortia (UK - SolarCap and Sweden - CAP) and euro42
million for the Dutch consortium to smaller budgets for local projects The projects at the European level are
more extensive The funds for all twenty FP7 projects related to artificial photosynthesis amount to a total
value of euro30 million AMPEA consists of around 400 professionals and an investment of approximately euro60
million contributed by the participants and associates themselves
Funding of AP research programmes and research consortia
EU ndash FP6 and FP7 projects
The FP6 and FP7 projects (6th
and 7th Framework Programmes for Research and Technological
Development) were undertaken in seven years between 2002 and 2013 and had a total budget of over euro60
billion30
Within FP7 around two thirds of the overall budget was aimed for the Cooperation programme of
which energy is one of the ten key thematic areas Investment in energy research under EU FP7 has been
around euro25 billion Various projects on artificial photosynthesis solar-powered hydrogen production by means
of water splitting have been completed under the EUrsquos Seventh Framework Programme Projects include
inter alia Solhydromics Solar-H Directfuel and H20Split FP7 is the key tool to respond to Europersquos needs in
terms of jobs and competitiveness and to maintain leadership in the global knowledge economy31
The
successor programme of FP7 has a number of projects in the field of artificial photosynthesis For example
PECDEMO project32
aims to develop a hybrid photoelectrochemical-photovoltaic tandem device with a solar-
to-hydrogen efficiency of 8-10 This illustrates the trend to move from fundamental research of materials and
processes (that was the main focus in FP6 and FP7 programmes) to the development of prototypes to reach
higher TRL levels (that is the main focus in H2020 programme)
An overview of the EU FP6 and FP7 projects on AP is presented in the table below
30
httpseceuropaeuresearchfp6pdffp6-in-brief_enpdf httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 31
httpseceuropaeuresearchfp7understandingfp7inbriefwhat-is_enhtml 32
httppecdemoepflchpage-113311-enhtml
68
Table 46 EU FP6 and FP7 projects on artificial photosynthesis
EU FP7 project Technology pathway Total budget EU contribution to
the total budget
Time
period
(months)
ARTIPHYCTION Photolectrocatalysis (Water Splitting ) euro 3594581 euro 2187040 36
DIRECTFUEL Synthetic Biology amp Hybrid Systems euro 4977781 euro 3729519 48
CO2PHOTORED Photolectrocatalysis (Water Splitting ) euro 176053 euro 176053 24
COFLeaf Photolectrocatalysis (Water Splitting ) euro 1497125 euro 1497125 60
EWOCS Photolectrocatalysis (Water Splitting ) euro 168896 euro 168896 24
FAST MOLECULAR
WOCS
Photolectrocatalysis (Water Splitting )
euro 100000 euro 100000 48
H2OSPLIT Photolectrocatalysis (Water Splitting ) euro 100000 euro 100000 48
HJSC Research for fundamental understanding euro 337094 euro 337094 36
NANO-PHOTO-
CHROME
Synthetic Biology amp Hybrid Systems euro 218731
euro 218731 17
HyMap Photolectrocatalysis (Water Splitting ) euro 2506738 euro 2506738 60
PCAP Photolectrocatalysis (Water Splitting ) euro 190800 euro 190800 36
PHOTOCATH2ODE Photolectrocatalysis (Water Splitting ) euro 1500000 euro 1500000 60
PHOTOCO2 Photolectrocatalysis (Water Splitting ) euro 50000 euro 50000 24
PS3 Synthetic Biology amp Hybrid Systems euro 1997944 euro 1997944 60
SOLAR-H Synthetic Biology amp Hybrid Systems euro 2316000 euro 1800000 36
SOLAR-JET Photolectrocatalysis (Water Splitting ) euro 3123950 euro 2173548 48
SOLHYDROMICS Synthetic Biology amp Hybrid Systems euro 3655828 euro 2779679 42
SUSNANO Catalysts can be either used for hybrid
systems or the water splitting category euro 100000
euro 10000 54
TRIPLESOLAR Photolectrocatalysis (Water Splitting ) euro 2493585 euro 2493585 60
light2hydrogen Photolectrocatalysis (Water Splitting ) euro 900000
Total euro 30005106 euro 24016752 821
Source FP7 Project list
In total euro30 million of which 80 were based on European contributions have been spent on 20 projects
related to artificial photosynthesis Most projects were completely funded by the European Union On average
the time period of these projects was around 43 months the shortest project lasting only 17 months and the
longest one 60 months Almost all funding related to the topics of photoelectrocatalysis (55) and synthetic
biology amp hybrid systems (44) Some additional funding was spent on research for fundamental
understanding (the HJSC project) and catalysts which are useful for either hybrid systems or water splitting
(the SUSNANO project)
Table 47 Total EU budget on artificial photosynthesis per technology pathway
Technology pathway TRL Total budget
Synthetic biology amp hybrid systems 1-2 euro 13166284
Photoelectrocatalysis (water splitting ) 1-4 euro 16401728
Catalysts that can be used for both categories above 1-4 euro 100000
Research for fundamental understanding - euro 337094
Total - euro 30005106
69
Based on the monthly funding of the FP7 projects33
it may be observed that annual investments in artificial
photosynthesis have been increasing over the years (Figure 43) There were no projects on artificial
photosynthesis in 2008 therefore no investments were made The highest investment was made in 2014 with
euro45 million spent on projects After that investments have been decreasing It is however expected that
from 2016 more projects on artificial photosynthesis will be conducted therefore investment will rise
Figure 43 Funding of FP6 and FP7 projects per year 2005 ndash 2020
Note It is assumed that the funding of the projects is evenly distributed over months Thus annual expenditures are
calculated as a sum of the monthly expenditures Project lsquolight2hydrogenrsquo is excluded from the calculation since there is no
information available on the number of months the project is running
Source Ecorys
EU ndash AMPEA (EERA)
EERA is an alliance of leading organisations in the field of energy research comprising more than 150
participating organisations all over Europe The primary focus of EERA is to accelerate the development of
energy technologies to the point that they can be embedded in industry-driven research Activities of EERA
are based on the alignment of own resources while over time the Joint Programmes can be expanded with
additional sources including from Community programmes34
In EERA approximately 3000 FTE (equivalent
of 3000 professionals) are involved which makes for a budget of around euro450 million35
AMPEA is one of the
programmes under EERA focusing on AP in which roughly 400 professionals are involved This would then
make for an investment of approximately euro60 million for AMPEA
The Netherlands ndash BioSolar Cells
The total budget of BioSolar Cells is around euro42 million based on public and private funds The Ministry
contributed euro25 million the NWO (The Dutch organisation on Scientific Research) euro35 million and Dutch
universities and research centres around euro7 million Private organisations invested euro65 million The specific
research programme Towards Biosolar Cells in which the Delft University of Technology is involved is
being allocated a budget of euro25 million by the Dutch Ministry of Agriculture Nature and Food Quality A
benefit of funding partly by private funding is the focus on building infrastructure and retaining key
33
It is assumed that funding is spread evenly over the months that the project is being implemented This means that if a project is running 36 months with a total budget of euro1 million it is assumed that monthly investments are euro83000 (1 million 12) If a project started in May 2010 then investment over the whole year 2010 is calculated as 8euro83000 After annual investment is calculated for all projects yearly total investment is calculated as a sum across projects
34 httpssetiseceuropaeuimplementationtechnology-roadmapeuropean-energy-research-alliance-eera
35 httpwwwapreitmedia168877busuoli_eneapdf
70
researchers Public funding of artificial photosynthesis is mostly for the short term facilitating the entry of new
groups36
Swedish ndash CAP
The Swedish Consortium for Artificial Photosynthesis connecting the universities of Lund Stockholm and
Uppsala is chaired by Stenbjoumlrn Styring There are 80 persons linked to the consortium In 2013 the Swedish
Energy Agency distributed the amount of euro118 million (SEK 108 million) in total to lsquosome of Swedenrsquos best
research groupsrsquo Out of this amount euro87 million went to three research groups at Uppsala University euro37
million to research on artificial photosynthesis to generate solar fuels euro32 million for research on dye-
sensitised solar cells and euro18 million to research on thin film solar cells (TFSC) It is the largest one-time
investment in solar energy ever in Sweden37
The Swedish Consortium for Artificial Photosynthesis ndash Stenbjoumlrn Styring
The project Molecular Solar Energy Sciences is funded by the KampA Wallenberg Foundation with euro5 million The main
research activities related to artificial photosynthesis include mechanistic studies on synthetic molecular and
moleculesemiconductor systems for the light-driven reduction of protons and CO2 and oxidation of water Furthermore
research is conducted on cyanobacteria systems for photo-biological fuel generation synthetic biology molecular
biology and metabolic engineering A second project on artificial photosynthesis is funded by the Swedish Energy
Agency (euro4 million) An additional four projects are funded by Swedish and European sources with a total of euro5
million38
UK ndash SolarCAP and others
The Engineering and Physical Sciences Research Council (EPSRC) in the UK supports several AP-related
projects through the Towards a Sustainable Energy Economy programme39
The total amount of funding is
approximately euro92 million
New and Renewable Solar Routes to Hydrogen is led by Imperial College London and is targeting both
artificial and natural photosynthetic routes to solar-derived hydrogen (euro5 million)40
Artificial Photosynthesis Solar Fuels is led by the University of Glasgow (euro2 million)41
The SolarCAP consortium for Artificial Photosynthesis is a consortium of five UK academic research
groups (based at the Universities of East Anglia Manchester Nottingham and York) they are working to
develop solar nanocells for the production of carbon-based solar fuels (euro22 million)
Funding of other AP initiativesprojects
Germany ndash German Aerospace Centre (DLR) and the Helmholtz Zentrum
The Helmholtz Zentrum is Germanyrsquos largest scientific organisation with more than 38000 employees and an
annual budget of more than euro4 billion42
It consists of 18 scientific technical biological and medical research
centres The research institutes of the German Aerospace Centre (DLR) are affiliated with the Helmholtz
Zentrum One of the Institutes of DLR the Institute of Solar Research forms part of the Helmholtz Zentrum
programme for renewable energies This programme focuses on projects on cost reduction in solar thermal
power plants the thermo-chemical generation of solar fuels in the period 2015-2019 the solar tower in Juumllich
the bioliq pilot plant and the Gross Schoumlnebeck geothermal research platform43
Research institutes submit
their research projects for evaluation by an international panel in order to qualify for funding under the
Renewable Energies Programme based on the outcome the Helmholtz Zentrum makes funding
recommendations for a five-year period
36
httpbiomassmagazinecomarticles2883towards-biosolar-cells-program-receives-government-funding 37
httpwwwuuseennewsnews-documentid=2282amptyp=artikelamparea=2amplang=en 38
Information is based on the survey responds 39
httpwwwrscorgglobalassets04-campaigning-outreachrealising-potential-of-scientistsresearch-policyglobal-challengessolar-fuels-2012pdf
40 httpgowepsrcacukNGBOViewGrantaspxGrantRef=EPF00270X1
41 httpgtrrcukacukprojectsref=EPF0478511
42 httpwwwdlrdesfendesktopdefaultaspxtabid-888515347_read-37692
43 httpwwwhelmholtzdeno_cacheenresearchenergyrenewable_energies
71
Germany ndash The Max Planck Institute for Chemical Energy Conversion (MPI CEC)
The MPI CEC was founded in 2012 to focus on the issue of energy conversion Its researchers analyse the
basic processes of energy storage and conversion within three research departments which encompass 200
employees44
The MPI CEC is for the most part financed by public funds from both the German state and
regions The MPI CEC is part of the Max Planck Society for the Advancement of Science which is a formally
independent non-governmental and non-profit association of German research institutes The budget of the
entire society amounted to euro17 billion in 2015
Germany ndash Federal Ministry of Education and Research (BMBF)
In 2010 the BMBF launched the initiative ldquoThe Next Generation of Biotechnological Processesrdquo45
Part of this
initiative were deliberations directed toward simulating biological processes for material and energy
transformation A funding amounting euro42 million is available for the first 35 projects on microbial fuel cells
artificial photosynthesis and universal production46
Germany ndash SolTech (Solar Technologies Go Hybrid)
The Government of Bavaria initiated SolTech an interdisciplinary project to explore innovative concepts for
converting solar energy into electricity and non-fossil fuels The project brings together research by chemists
and physicists at five different Bavarian Universities and is funded with euro50 million for the period 2012-201647
The SolTech network covers all fields of research on solar energy use such as the conversion of solar energy
to electricity for immediate use and the conversion of solar energy into chemical energy for storage and future
use
France - Alternative Energies and Atomic Energy Commission (CEA)48
CEA is a public government-funded research organisation active in four main areas low-carbon energies
defence and security information technologies and health technologies The CEA is the French Alternative
Energies and Atomic Energy Commission The CEA had a total budget of euro43 billion and around 16000
permanent staff On photovoltaic cell technology CEA is collaborating with Photowatt Pechiney and Appolon
Solar and on photovoltaic modules and systems with TOTAL Energie
UK - University of East Anglia (UEA) Cambridge and Leeds
A specific research programme by the UEA on the creation of hydrogen with energy derived from
photocatalysts designed to replicate photosynthesis is funded by the Biotechnology amp Biological Sciences
Research Council (BBSRC) The total amount of funding is approximately euro1 million (pound800000)49
432 Research investments outside Europe
The main research programmes and consortia discussed are JCAP (US) SOFI (US) ARPChem (Japan)
AnApple (Japan) and KCAP (Korea) In contrast to Europe the use of energy innovation hubs ie major
integrated research centres drawing together researchers from multiple institutions and varied technical
backgrounds is more common in the US and Asia Also partnerships between the government academia
and industry seem to be more common in those areas than they are in Europe The idea of developing new
energy technologies in innovation hubs is very different compared to the approach of helping companies scale
up manufacturing through grants or loan guarantees50
The information on the budgets from the large
networks is generally available
44
httpwwwcecmpgdeinstitutdaten-faktenhtml 45
httpswwwbiotechnologiedeBIONavigationENrootdid=164934htmlview=renderPrint 46
httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf 47
httpwwwsoltech-go-hybriddeabout-soltech 48
httpenglishceafrenglish-portal 49
httpwwwwiredcouknewsarchive2013-0122artificial-photosynthesis 50
httpswwwtechnologyreviewcoms429681artificial-photosynthesis-effort-takes-root
72
Funding of AP research programmes and research consortia
Japan ndash ARPChem
In Japan the Ministry of Economy Trade and Industry (METI) and the Ministry of Education Culture Sports
Science and Technology (MEXT) launched a large artificial photosynthesis project that will tackle the study for
the coming decade between 2012 and 2021 with an expected budget of about euro122 million (15 billion yen)
The main organisation to conduct the project is the Japan Technological Research Association of Artificial
Photosynthetic Chemical Process (ARPChem)51
Japan ndash AnApple
All Nippon Artificial photosynthesis Project for Living Earth (AnApple) is a five-year research programme
(2012-2017) joined by more than 40 Japanese leading scientific groups In this strong collaboration they aim
at achieving breakthroughs for the realisation of artificial photosynthesis AnApple hosted The International
Conference on Artificial Photosynthesis (ICARP)rdquo in 2014 and receives strong financial support52
from the
Ministry of Education Culture Sports Science and Technology
Korea ndash KCAP
The Korea Center for Artificial Photosynthesis (KCAP) at Sogang University was established in September
2009 through complementary and collaborative research with the Lawrence Berkeley National Lab (LBNL) in
the US to build the foundation for the realisation and commercialisation of artificial photosynthesis KCAP
receives a grant of euro385 million (50 billion won in 10 years) from the Ministry of Education Science and
Technology (MEST) through the National Research Foundation of Korea (NRF)
US - JCAP
JCAP (Joint Centre for Artificial Photosynthesis) was established in 2010 by the Department of Energy as one
of the Energy Innovation Hubs with a fund of euro108 million ($122 million) for five years Additional funding for
the next five years amounts to euro67 million ($75M) but is still subject to congressional appropriation53
JCAP
is the largest artificial photosynthesis research programme in the world There are 190 persons linked to the
research programme
US ndash SOFI
In 2012 the Solar Fuels Institute (SOFI) based at Northwestern University was launched This institute is a
research consortium of universities government labs and industry united around the goal of developing and
commercialising a liquid solar fuel within 10 years SOFI (Solar Fuels Institute) is focused on light capture
water splitting CO2 catalysis and photoelectrochemical cells SOFI relies on a community of member
institutions and individual supporters who believe strongly in a clean energy future54
The solar fuel created
using catalysts and technology shared by global members of SOFI is funded by crowdfunding campaigns
(Kickstarter campaign) Furthermore SOFI partnered with TSRC to raise by means of a bold campaign one
billion dollars over the next ten years to fund the research55
Funding of other AP initiativesprojects
US ndash Plug-and-play photosynthesis CAPP (combining algal and plant photosynthesis)
Three UKUS-funded projects received funding to improve photosynthesis The three research teams (each
comprised of scientists from the United Kingdom and the United States) have been awarded a second round
of funding to build on their research findings and develop new ways to improve photosynthesis Projects
include plug-and-play photosynthesis by the Arizona State University Multi-level Approaches for Generating
Carbon Dioxide (MAGIC) led by the Pennsylvania State University and Combining Algal and Plant
Photosynthesis (CAPP) led by the Stanford University received in 2014 a new round of funding of euro44 million
51
httpwwwmetigojpenglishpress20121128_02html 52
httpartificial-photosynthesisnetICARP2014scopehtml The concrete funding figures are not available 53
httpenergygovarticlesenergy-department-provide-75-million-fuels-sunlight-hub) httpsolarfuelshuborgresearchoverview 54
httpwwwsolar-fuelsorgdonate 55
httpstelluridescienceorgsofi-brochurepdf
73
(pound5 million) in total over three years from the Biotechnology and Biological Sciences Research Council
(BBSRC) and the National Science Foundation56
Israel ndash Projects funded by AERI
AERI is providing a pool of funds to try out new ideas and jump-start research projects that are not applicable
for conventional grants Since 2006 already 8 cycles of AERI-funded projects took place Projects under the
20132014 cycle include lsquoNew Options for Solar Energy Conversion to Biofuel and Electricity ndash Biofuels ndash
Photovoltaics and Opticsrsquo57
Funding is provided by the Canadian Center for Alternative Energy Research the
Helmsley Energy Program the Helmsley Charitable Trust (providing euro13 million ($15 million) over three
years) the Burk Fund for Alterative Energy Studies the Eisenberg Foundation and individuals58
China ndash Funding of the Dalian National Laboratory for Clean Energy
The Dalian National Laboratory for Clean Energy was established in 2011 The investments into this lab
amount to more than euro40 million (289 million RMB) a year (over 50 of annual research of the Dalian
University of Technology within which the laboratory functions)59
In addition to this laboratory Haldor Topsoe
opened an RampD Center60
at the same university to join forces in the research of clean energy Haldor Topsoe
is also going to sponsor RampD projects however the size of the investments is not revealed Prior to that
Topsoe already established a scholarship with a value of around euro400 a month (3000 RMB)61
44 Strengths and weaknesses
This section presents the analysis of the strengths and weaknesses of the research community in the field of
artificial photosynthesis The findings are based on the results of the survey conducted during March 2016
and are supplemented by desk research Firstly we outline the main strengths and weaknesses with regard to
global AP research Secondly the strengths and weaknesses of the European community compared to the
non-European community are presented
441 Strengths and weaknesses of AP research in general
Table 48 below summarises the strengths and weaknesses of research in AP taking a global perspective
Table 48 Summary of strengths and weaknesses of research globally
Strengths Weaknesses
A diverse community of researchers bringing together
experts in chemistry photochemistry electrochemistry
physics biology catalysis etc
Researchers focus on all technology pathways in AP
Existing research programmes and roadmaps in AP
Available financial investments in several countries
Limited communication cooperation and collaboration
at an international level
Limited collaboration between academia and industry
at an international level
Transfer from research to practical applications is
challenging
Note International level refers not only to EU countries but all around the world
Globally there is a wide variety of RampD institutes (and researchers) focused on AP forming a diverse
community of researchers Research in AP requires interdisciplinary teams The experts working together
on this topic often have backgrounds in chemistry physics and biology
56
httpwwwbbsrcacuknewsfood-security2014140602-pr-bbsrc-and-nsf-funding-photosynthesis 57
httpwwwweizmannacilAERIresearch 58
httpwwwweizmannacilresdevsitesweizmannacilresdevfilesenergy_booklet_lo_res_2012pdf 59
httpwwwnaturecomnews2011111031fullnews2011622html 60
httpwwwtopsoecomnews201602topsoe-establishes-rd-center-dalian-institute-chemical-physics-china 61
httpwwwdnlorgcnshow_enphpid=776
74
A diverse community of researchers is focusing on all the pathways in AP which ensures diverse
approaches an exchange of different views a dynamic research community and avoids lock-ins into one
specific pathway This broad and inclusive research approach is the best way to maximise the probability of
AP research being successful in developing efficient and commercially viable AP processes
Several countries have dedicated programmes andor roadmaps to the topic of AP The US Japan the
Netherlands and South Korea have invested in large-scale interdisciplinary research programmes (specifically
on solar fuels) China and Japan have dedicated centres for renewable energy research where solar fuels are
an area of substantial effort For example the Department of Energy of the US sponsors Energy Innovation
Hubs aiming to overcome scientific barriers to develop a complete energy system with the potential to turn into
a transformative energy technology62
One of such innovation hubs is the Joint Center for Artificial
Photosynthesis established in 2010 In the Netherlands a public private partnership was established to form
BioSolar Cells of which one of the main focal themes is AP Globally several hundreds of millions of euros
are being spent this decade on AP research and this research seems to be intensified further
Despite the intensification of global research efforts the communication cooperation and collaboration at
an international level remains limited Many AP consortia link different research groups but operate only at
a national level63
Yet a higher level of institutionalised international or global cooperation going beyond
international academic conferences could spur innovative research in the field and enhance knowledge
exchange and spill-overs A number of survey respondents indicated that the lack of coordination
communication and cooperation at an international level is one of the main weaknesses in current AP-related
research activities
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research
including research on artificial photosynthesis In Japan the industry is involved in AP research to a greater
degree64
Nevertheless although companies are participating in local consortia such as ARPChem and
BioSolar Cells there seems to be a lack of cooperation between academia and industry at an
international level
The transfer of research to industrial application in artificial photosynthesis remains challenging In order
to attract the attention of the private sector artificial photosynthetic systems must be cost-effective efficient
and durable An active involvement of industrial parties could help bringing research prototypes to
commercialisation This step towards commercialisation requires a sufficient critical mass and funding
however which cannot be borne by a single country
442 Strengths and weaknesses of AP research in Europe
Table 49 below summarises the strengths and weaknesses of research in artificial photosynthesis in Europe
as compared to non-European research
62
httpscienceenergygovbesresearchdoe-energy-innovation-hubs 63
The only exception is AMPEA with its pan-European reach 64
The Korean Centre for Artificial Photosynthesis (KCAP) collaborates with a number of companies Toshiba and Panasonic made some advances in artificial photosynthesis research (httpasianikkeicomTech-ScienceScienceHow-artificial-photosynthesis-could-cut-emissions) ARPChem has a few corporate members on board (httpwwwmetigojpenglishpress2012pdf1128_02bpdf)
75
Table 49 Summary of strengths and weaknesses of research in Europe
Strengths Weaknesses
A strong diverse community of researchers
RampD institutions research capacity and facilities
Existing research programmes and roadmaps for AP in
several MS
Available financial investments in MS
Ongoing and conducted FP7 projects at EU level
Close collaboration of research groups in consortia
Limited communication cooperation and collaboration at
a pan-European level
Limited collaboration between academia and industry
within Europe
Limited funding mostly provided for short-term projects
focusing on short-run returns
National RampD efforts in AP are scattered
Europe has a diverse research community working on artificial photosynthesis research covering all the
technology pathways Europersquos universities have many highly educated researchers in the fields of chemistry
physics and biology at their disposal There is a solid foundation of RampD institutions research capacity
and facilities such as specialised laboratories which work together at a national level
National research programmes and roadmaps for AP exist in several Member States an indication that
AP research is on the agenda of European governments65
Therefore also financial investment for AP
research is available in several MS such as in Germany66
and other countries European-level
collaboration between different research groups and institutes from different countries has been achieved in
the framework of FP7 projects67
as well as predecessors of it
Five main consortia in Europe ensure that research groups and research institutes are collaborating
closely68
such as in Sweden where the Consortium for Artificial Photosynthesis (CAP) is active and in the
Netherlands where researchers work in close cooperation within the BioSolar Cells consortium Nevertheless
there is still much room to expand globally as well as within Europe most consortia are operating within and
collaborating with research groups in countries where they are based themselves
The level of cooperation and collaboration at a pan-European level hence seems to be limited There
are a few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7 projects
but many research groups are operating locally and are funded by national governments Several survey
respondents reported a low degree of collaboration among different research groups which typically results in
a duplication of efforts and a lack of generalised standards Synergies which could potentially boost research
in artificial photosynthesis are being overlooked Creating for example a communication platform to facilitate
the exchange among researchers could more easily promote the development of knowledge and increase the
speed of discovery and exploitation of new robust (effective and durable) photocatalysts innovative processes
and devices etc Moreover another indicated weakness is the lack of collaboration between already existing
and ongoing projects
While industrial companies are present in a few consortia there is limited collaboration between European
academia and industry Improved collaboration could result in the development of more advanced AP
processes and AP process devices and it might improve the probability of APrsquos successful commercialisation
in the foreseeable future
65
For example Strategic Energy Technology (SET) Plan European Biofuels Technology Platform (EBTP) and European Industrial Bioenergy Initiative (EIBI) JCAP scientific programme For more information please refer to Deliverable 1 Chapter 32
66 By now research funded by the government of Germany in the field of artificial photosynthesis amounts to euro 42 million (httpswwwbmbfdepubBiooekonomie_in_Deutschland_Engpdf)
67 See Deliverable 1
68 httpswwwleopoldinaorgenpolicy-adviceworking-groupsartificial-photosynthesis
76
The long-term focus of AP research is a hurdle for both gaining cooperation with industry and for obtaining
funding Compared to that of its non-European counterparts European funding focuses on the short
term69
While in the USA and Japan funding is dedicated for about 5-10 years European parties often get
funding for about 4 years at the most Although several MS also have dedicated RampD programmes focusing
on AP the amounts provided by non-European counterparts exceed those of the European70
Furthermore
these national programmes are fragmented ie lacking a common goal and perspective hence the funding
of research is also fragmented and scattered71
The European community of researchers could benefit
from an integrated programme which clearly indicates research goals and objectives In addition a common
funding scheme set up to support fundamental research in artificial photosynthesis and to promote
collaboration with industry could advance the research in artificial photosynthesis
A number of survey respondents indicated that there is currently little focus of EU-funded research on
technologies with low TRL within H2020 At the moment there is a strong emphasis on the projects and
technologies which already have a rather high TRL expecting returns in the near future while research in the
area of low TRL technologies requires some attention and funding Several respondents mentioned that there
exist still quite some barriers regarding the design of low-cost materials with low TRL and with higher stability
and activity (eg performance of devices when it comes to a discontinuous supply of energy)72
45 Main industrial actors active in AP field
451 Industrial context
The idea behind artificial photosynthesis is that solar fuels could solve worldwide energy problems by using
water and carbon dioxide and converting them into the fuels we need Artificial photosynthesis can convert
sunlight directly into chemical fuels which makes it possible to harvest and store energy However there are
still many obstacles to make this technology commercially viable Only if artificial photosynthesis can be
provided efficiently stably safely and cheaply will it be beneficial for the public This means inter alia that an
efficient light absorber and catalysts need to be created to convert sunlight into fuel Even though there are
rapid developments in the field of artificial photosynthesis there are many obstacles to overcome in order to
reach mass production Currently the positioning of the fields of artificial photosynthesis and solar fuels is at
around a 3 on the technology readiness level
452 Main industrial companies involved in AP
At the moment the number of companies active in the field of AP is limited Based on our analysis of the main
AP actors in the industry only several tens of companies appear to be active in this field Moreover industrial
activity is limited to research and prototyping as viable AP technologies have not (yet) been commercialised
35 companies active in the field of AP have been identified comprising 16 European companies and 19 non-
European companies (Table 410) Seven of these are in Germany eight in the Netherlands eight in Japan
and 10 in the US The following table summarises the countries in relation to one or more of the technology
pathways
69
Already in 2013 it was indicated that much of public funding of basic AP research remains short term For more information see Thomas FaunceStenbjorn Styring Michael R Wasielewski Gary W Brudvig A William Rutherford et al (2013) Artificial Photosynthesis as a Frontier Technology for Energy Sustainability Energy amp Environmental Science Issue 4 2013
70 A number of respondents indicated that the available funding is not sufficient to finance research facilities and equipment
71 This weakness is indicated by several respondents
72 This is also mentioned as one of the areas of attention in Artero F Chandezon D Co B Dietzek (forthcoming) European and international initiatives in the field of artificial photosynthesis rdquo in ldquoArtificial Photosynthesisrdquo B Robert (Ed) Elsevier (in press)
77
Table 410 Overview of the size of the industrial community number of companies per pathway
Country Synthetic biology amp
hybrid systems
Photoelectrocatalysis Co- electrolysis Total number of
companies
European companies
France 1 1 0 1
Germany 2 2 0 4
Italy 0 1 0 1
Netherlands 3 4 1 8
Switzerland 0 1 0 1
Total 6 9 1 15
Non-European companies
Japan 0 8 0 8
Saudi Arabia 0 1 0 1
Singapore 0 0 1 1
US 3 2 4 8
Total 3 11 5 19
Note a company can be active in multiple technology pathways
Source Ecorys
With respect to the industry largely the same countries stand out as in the research field namely Japan the
US and north-western Europe The industry in Japan appears to have the most intensive research activities
in AP as several large Japanese multinationals have set up their own AP RampD laboratoriesresearch
departments
With respect to the three technology pathways (i) synthetic biology amp hybrid systems (ii) photoelectrocatalysis
and (iii) co-electrolysis we have observed that most industrial (research) activity is being performed
concerning photoelectrocatalysis (19 companies) although there are also companies active in the two other
pathways
We have also identified a number of companies active in the area of carbon capture and utilisation that might
potentially be involved in the research of artificial photosynthesis
453 Companies active in synthetic biology amp hybrid systems
The pathway involving synthetic biology amp hybrid systems is still at an early stage on the TRL scale (TRL 1-2)
The challenges industries face relate mostly to efficiency obstacles Enzymes and proteins need to be
modified by genetic engineering Another barrier relates to the fact that the modifications and protein
production are still very time-consuming in terms of cell growthprotein purification Furthermore it is
necessary to improve protein stability and solubility by rational design directed evolution and modifying
sample conditions since currently proteins are unstable It would probably take about 10-20 years until
technologies reach TRL 7
The companies involved in this pathway range from chemical and oil-refining companies companies working
on bacteria companies producing organic innovative catalysts to others The following table lists the
organisations identified within this pathway
78
Table 411 Organisations in synthetic biology amp hybrid systems
Country Organisation (in EN)
France PhotoFuel
Germany Evonik Industries AG
Germany Brain AG
Italy Hysytech
Netherlands Biomethanol Chemie Nederland BV
Netherlands Photanol BV
Netherlands Tendris Solutions
Netherlands Everest Coatings
US Joule Unlimited
US Phytonix
US Algenol
Source Ecorys
Chemical and oil-refining companies
Biomethanol Chemie Nederland BV a Dutch company that produces and sells industrial quantities of high
quality bio-methanol focusing on synthetic biology amp hybrid systems is also a partner of the BioSolar Cells
programme The BioSolar Cells programme focuses its research on artificial photosynthesis photosynthesis in
cellular systems and photosynthesis in plants
Companies working on bacteria
Another group of companies in the pathway of synthetic biology amp hybrid systems focus on CO2 to fuel
processes that use cyanobacteria to convert CO2 into targeted fuels or chemicals (biological conversion)
Examples of such companies are Joule Unlimited Phytonix and Algenol all based in the US Algenol is
commercialising its patented algae technology platform for the production of ethanol using proprietary algae
sunlight carbon dioxide and saltwater The Dutch company Photanol uses cyanobacteria to turn CO2 into
certain predetermined products
Companies producing organic innovative catalysts
Many of the smaller companies currently active in developing AP originate from a specific research group or
research institute and focus on specific AP process steps andor process components Some companies
focus on the further development of both chemical and organic innovative catalysts which are earth-abundant
non-toxic and inexpensive Brain AG (Germany) is an example of such a company
Other companies
Hysytech is an Italian company experienced in technology development and process engineering applied to
the design and construction of plants and equipment for fuel chemical processing energy generation and
photoelectrocatalysis Hysytech is involved in an FP7 project to develop a fully artificial photoelectrochemical
device for low temperature hydrogen production
Other companies in the field of synthetic biology amp hybrid systems are Tendris Solutions (Netherlands) and
Everest Coatings (Netherlands) involved in the EET-Kiem project which focused on increasing the
absorption of visible light in the TiO2 photocatalyst by incorporating other elements in the structure and to
construct a photoelectrochemical reactor Photofuel in France and Phytonic in the US focus on synthetic
biology amp hybrid systems and photoelectrocatalysis Evonik Industries AG invests in synthetic biology amp
hybrid systems as well as carbon capture technologies which convert waste CO2 into products and fuels
79
454 Companies active in photoelectrocatalysis
The pathway of photoelectrocatalysis is relatively low on the TRL scale as well (TRL 1-4)
Photoelectrocatalysis would make it possible to use photovoltaic cells that absorb photons to facilitate water
splitting Research on photoelectrocatalysis using photoelectrochemical cells in particular is still at a very early
stage
Technologies pertaining to the photoelectrocatalysis pathway are not yet commercially viable with the main
challenges relating to the design of devices that are efficient stable and durable Further potential obstacles to
be taken into account relate to the incorporation of these technologies with other technologies that can
generate fuel molecules other than hydrogen
Most companies are involved in this pathway ranging from automotive manufacturers and electronic
companies to chemical and oil-refining companies The following table lists the organisations identified within
this pathway
Table 412 Organisations in the field of photoelectrocatalysis
Country Organisation (in EN)
France PhotoFuel
Germany Bauhaus Luftfahrt eV (Bauhaus Luftfahrt Research)
Germany ETOGAS
Italy Hysytech
Japan Toyota (Toyota Central RampD Labs)
Japan Honda (Honda Research Institute - Fundamental Technology Research Center)
Japan Mitsui Chemicals
Japan Mitsubishi (Mitsubishi chemicals Setoyama Laboratory)
Japan Sumitomo Chemicals (Energy amp Functional Materials Research Laboratory)
Japan INPEX Corporation
Japan Toshiba (Corporate Research and Development Center)
Japan Panasonic (Corporate Research and Development Center)
Netherlands InCatT BV
Netherlands Shell (Shell Game Changer Programme)
Netherlands Hydron
Netherlands LioniX BV
Saudi Arabia Saudi Basic Industries Corporation
Switzerland SOLARONIX SA
US HyperSolar
Source Ecorys
Companies in the automotive sector
Several automotive manufacturers are active in the field of AP mostly relating to the field of
photoelectrocatalysis In 2012 Honda opened a hydrogen station in Saitama Japan that converts sunlight
into hydrogen that could be used to power fuel-cell electric vehicles The station is focusing on
photoelectrocatalysis and turning sunlight into hydrogen via a high-pressure water electrolysis system that
was developed by Honda itself Since then there seems to be little activity from Honda73
73
httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
80
Figure 44 Hondarsquos sunlight-to-hydrogen station
Source httpworldhondacomworldnews20124120327Solar-Hydrogen-Stationindexhtml
Toyota succeeded (in 2011) to generate organic compounds via artificial photosynthesis without using any
external energy andor material sources The system is focused on producing formic acid (which could be
used as a raw material in industry) In February 2016 Toyota Central RampD Labs announced that they
achieved the worldrsquos highest energy conversion efficiency rate of 46 with artificial photosynthesis using
water and carbon dioxide as raw materials and sunlight as energy to produce useful materials Toyota is also
researching new chemical reactions to generate more valuable organic compounds as a final product such as
methanol Toyota is primarily focused on photoelectrocatalysis The companyrsquos 2020 goal is to complete basic
testing for the creation of primary CO2-absorbing materials (material or fuel)74
Electronic companies
In addition to car manufacturers also electronic companies are involved in photoelectrocatalysis In December
2014 Toshiba announced its focus on producing a catalyst made of gold The company indicated that they
found a way to modify gold at the atomic level using nanotechnology which allows carbon dioxide to change
into other compounds at a lower voltage (with a record of 15 energy efficiency rate)75
In September 2015 Toshiba made public that the company developed a prototype of a new highly efficient
molecular catalyst (consisting of an imidazolium salt) that converts carbon dioxide into ethylene glycol without
producing other and unwanted by-products Most artificial photosynthesis technologies use a two-electron
reduction conversion process producing carbon monoxide and formic acid Others can achieve direct multi-
electron reduction but tend to produce many by-products and their separation can be problematic Toshibas
new molecular catalyst converts carbon dioxide into ethylene glycol via multi-electron reduction The long-term
goal of Toshibarsquos research work is to develop a technology compatible with carbon dioxide capture systems
installed at facilities such as thermal power stations and factories utilising carbon dioxide to provide (storable)
energy To this end Toshiba focuses on photoelectrocatalysis and further improvement of the conversion
efficiency by increasing catalytic activity and aims at practical implementation in the 2020s76
Panasonics artificial photosynthesis system is also focused on photoelectrocatalysis in particular on highly
efficient CO2 conversion which can utilise direct sunlight or focused light In 2012 Panasonic found that a
nitride semiconductor has the capability to excite the electrons with enough high energy for the CO2 reduction
reaction to take place Nitride semiconductors have attracted attention for their potential applications in highly
74
httpwwwtytlabscom and httpswwwasiabiomassjpenglishtopics1603_01html 75
httpwwwjapantimescojpnews20150412nationalscience-healthlab-photosynthesis-begins-to-bloomVw1YZP5f3IV 76
httpswwwtoshibacojprdcrddetail_ee1509_01html
81
efficient optical and power devices for energy saving However its potential was revealed to extend beyond
solid devices more specifically it can be used as a photoelectrode for CO2 reduction By making a devised
structure through the thin film process for semiconductors the performance as a photoelectrode has greatly
improved77
In September 2014 Panasonic Corporation managed to achieve a conversion efficiency rate of
0378
and not long after that the company announced to having achieved the first formic acid generation
efficiency of approximately 10 as of November 201479
According to Panasonic the key to achieving an
efficient artificial photosynthetic system lies in improved photoelectrodes and oxidation-reduction electrodes
Chemical and oil-refining companies
The developments with respect to solar fuels are also being supported by several chemical and oil-refining
companies Artificial photosynthesis has been an academic field for many years However in the beginning of
2009 Mitsubishi Chemical Holdings reported to be undergoing its own artificial photosynthesis research by
using sunlight water and carbon dioxide to create the carbon building blocks from which resins plastics and
fibres can be synthesisedrdquo80
In 2014 Mitsubishi established the research organisation Setoyama Laboratory
The Laboratory focuses on the development of artificial photosynthesis for chemical processes which is the
synthesis of raw materials such as ethylene propylene butenes etc by means of solar hydrogen obtained by
catalytic water splitting under visible light and CO2 emitted at a plant site81
The laboratory is also participating
in the ldquoArtificial Photosynthetic Chemical Processrdquo project (denoted ldquoARPChemrdquo) granted by NEDO (New
Energy Development Organization) In this project the following three programmes are conducted through
collaboration with academia and industry
1 Design of a photo semiconductor catalyst for water splitting
2 A membrane separation system for H2 from gas mixtures composed of H2 and O2 and
3 A catalytic process for the synthesis of lower olefins from H2 and CO2
The Japanese chemical companies Sumitomo chemicals and Mitsui Chemicals focusing on carbon
capture and photoelectrocatalysis are also participating in the ARPChem programme Sumitomo has its
own Energy amp Functional Materials Research Laboratory and is conducting research and development in a
broad range of fields Mitsui created the Mitsui Chemicals Catalysis Science Award and the Mitsui Chemicals
Catalysis Science Award of Encouragement in order to award recognition to national and international
researchers that have made substantial contributions to the field of catalysis science In 2014 it was the fifth
time that Mitsui has given these awards
Royal Dutch Shell cooperated with Bauhaus Luftfahrt in the EU-funded Solar-Jet project (2011-2015) in the
area of photoelectrocatalysis aimed at demonstrating an innovative process technology using concentrated
sunlight to convert carbon dioxide and water into synthesis gas (syngas) The syngas a mixture of hydrogen
and carbon monoxide is ultimately converted into kerosene by means of the commercial Fischer-Tropsch
technology With the first ever production of synthesised ldquosolarrdquo jet fuel the SOLAR-JET project has
successfully demonstrated the entire production chain for renewable kerosene obtained directly from sunlight
water and carbon dioxide (CO2)82
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University (US)
SOFI leads a global consortium that brings together universities from Rutgers University in New Jersey to
Uppsala University in Sweden83
SOFI focuses on both the water-splitting process (production of hydrogen)
and the CO2 reduction process (the reduction of carbon dioxide to carbon monoxide which in combination
77
httpnewspanasoniccomglobalpressdata201207en120730-5en120730-5html 78
httpswwwasiabiomassjpenglishtopics1603_01html 79
httpwwwpanasoniccomglobalcorporatetechnology-designtechnologyphotosynthesishtml 80
httpwwwdigitalworldtokyocomindexphpdigital_tokyoarticlesmanmade_photosynthesis_looking_to_change_the_world 81
httpwwwmcrccojpenglishrdsetoyama_laboratoryhtml 82
httpwwwsolar-jetaeropagepostsartsunlight-to-jet-fuel-european-collaboration-solar-jet-for-the-first-time-demonstrates-the-entire-production-path-of-ldquosolarrdquo-kerosene-4php
83 httpappsnorthbynorthwesterncommagazine2015springsofi
82
with hydrogen can be processed into eg methanol or synthetic gasoline) Total is also a partner of the
BioSolar Cells programme
INPEX Corporation is a Japanese oil company established in February 1966 as North Sumatra Offshore
Petroleum Exploration Co In addition to Mitsubishi Chemicals Sumitomo Chemicals and Mitsui Chemicals
INPEX also participates in the ldquoJapan Technological Research Association of Artificial Photosynthetic
Chemical Processrdquo (ARPChem) programme and engages in RampD projects with the aim to produce chemical
products like plastics and hydrocarbon fuel from photochemical catalysis INPEX Corporation is focused on
photoelectrocatalysis
Other companies
Other companies include Etogas (Germany) which develops builds and selects Power-to-Gas plants and
products related to Power-to-Hydrogen Power-to-SNG and Hydrogen-to-SNG LnCatT BV (Netherlands)
Hydron (Netherlands) Saudi Basic Industries Corporation (Saudi Arabia) and Hyper Solar () all focus on
photoelectrocatalysis LioniX BV (Netherlands - photoelectrocatalysis) and Solaronix SA (Switzerland -
photoelectrocatalysis) are focused on the further development of photoelectrochemical cells Hysytech and
Photofuel are in addition to the first pathway also involved in the second
455 Companies active in co-electrolysis
Even though co-electrolysis is the pathway at the highest levels of technical readiness compared to the other
two pathways not many companies are involved in it There are three electrolyser types capable of producing
hydrogen gas eg alkaline electrolysis polymer electrolyte membrane electrolysis and solid oxide electrolysis
cells (SOECs) Multiple designs are commercialised although SOECs using Fischer-Tropsch synthesis are
not yet commercially viable The companies involved in this pathway are mainly from the US Industries
combine co-electrolysis and the field of carbon capture Fuel cell products are used in the automotive
telecom defenceaerospace and consumer product sectors
The following table summarises the organisations in the field of co-electrolysis
Table 413 Companies in co-electrolysis
Country Organisation (in EN)
Netherlands Shell (Shell Game Changer Programme)
Singapore Horizon Fuel Cell Technologies
US Catalytic Innovations
US Opus 12
US LanzaTech
US Proton onsite
Source Ecorys
Companies include Proton onsite (US ndash PEM electrolysis) which manufactures hydrogen nitrogen and zero
air generators in a safe reliable and cost-effective way Horizon Fuel Cell Technologies (Singapore)
focuses on commercially viable fuel cells starting by simple products which need smaller amounts of
hydrogen The technology platform of horizon fuel cell technology is focused on three main topics PEM fuel
cell systems hydrogen supply and hydrogen storage Catalytic Innovations (US) Opus 12 (US) Lanzatech
(US) and Shell (NL) are also involved in the second pathway
83
456 Companies active in carbon capture and utilisation
The technology in the carbon capture and storage pathway can capture up to 90 of the CO2 and allows for
the separation of carbon dioxide from gases produced in electricity generation and industrial processes by
means of combustion capture and oxyfuel combustion The most advanced technologies are at TRL 7 eg
carbon capture in a coal plant
The following table shows the organisations active in the field of carbon capture and utilisationre-use
Table 414 Organisations active in carbon capture and utilisation
Country Organisation (in EN)
Denmark Haldor Topsoe
Germany Evonik Industries AG
Germany Siemens (Siemens Corporate Technology CT)
Germany Sunfire GmbH
Germany Audi
Switzerland Climeworks
UK Econic (Econic Technologies)
Canada Carbon Engineering
Canada Quantiam
Canada Mantra Energy
Iceland Carbon Recycling International
Israel NewCO2Fuels
Japan Mitsui Chemicals
US Liquid light
US Catalytic Innovations
US Opus 12
US LanzaTech
US Global Thermostat
Source Ecorys
Twelve companies currently only focus on carbon capture and utilisation These companies are therefore
technically not considered to be companies involved in artificial photosynthesis However they can potentially
be involved in AP research in the future Such companies include automotive manufacturers as well as
electronics companies Five companies are involved in carbon capture and one of the pathways
Automotive manufacturers
Audi is working together with the American company Joule Unlimited in order to research and produce lsquoe-
ethanolrsquo Joule optimised a production process in which microorganisms are able to produce and excrete
either ethanol or alkanes from carbon dioxide (CO2) and sunlight Audi and Joule opened a joint
demonstration plant in September 2012 where e-ethanol is produced in transparent plastic tubes (see Figure
45)
84
Figure 45 Demonstration facility of Audi and Joule in Hobbs (New Mexico)
Source httpwwwbest-practicesfrost-multimedia-wirecomjoule2015
In January 2014 Audi e-ethanol underwent its first-ever test cycle in the pressure chamber and glass engine
showing that fewer pollutants are produced in the combustion of e-ethanol than is the case with bio-ethanol84
Since 2011 Audi has also been collaborating with Joule to produce e-diesel Finally in November 2014 Audi
opened a research facility in Dresden with project partners Climeworks and the start-up Sunfire in order to
produce its first batches of synthetic diesel combining two innovative technologies CO2 capture from the
ambient air (Climeworks) and the power-to-liquid process for the production of synthetic fuel (Sunfire)85
Currently Audi is investing in carbon capture and utilisation technologies
Electronics companies
Electronics companies such as Siemens are also investing in carbon capture technologies Developers at
Siemens Corporate Technology (CT) in Munich are currently active in the project CO2-to-value The challenge
of the project is to charge only carbon dioxide with electrons and not the surrounding water molecules
because the latter would merely result in the production of conventional hydrogen Specialists at the University
of Lausanne in Switzerland and materials scientists at the University of Bayreuth are working with Siemens to
develop catalysts on their behalf Siemens takes on a pragmatic approach by focusing on only one step in the
AP process They are not yet trying to capture light Instead they are centring their research activities on
activating CO2 and converting it into products such as (i) ethylene which the chemical industry needs for the
production of plastics (ii) methane the main component of natural gas and (iii) carbon monoxide which can
be used to produce fuels such as ethanol86
Other companies
Figure 46 illustrates the process of NewCO2Fuels (NCF) an Israeli company focused on carbon capture
This is a high-temperature-driven CO2- and water-dissociation process that produces syngas (a mixture of
CO and H2) from which various synthetic fuels and chemicals can be produced
In the short term NCF is focusing on the design and building of a first pilot plant as well as raising the
necessary funds for it
In the mid term NCF plans to offer its technology to the energy intensive industries such as the steel
gasification and glass industries to transform their CO2 waste streams into feedstock
In the long term NCFrsquos vision is to use solar energy to convert CO2 captured immediately from the
atmosphere into valuable products
84
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 85
httpwwwaudicomcorporateencorporate-responsibilitywe-live-responsibilityproductsynthetic-fuels-Audi-e-fuelshtml 86
httpwwwsiemenscominnovationenhomepictures-of-the-futureresearch-and-managementmaterials-science-and-processing-co2tovaluehtml
85
Figure 46 Illustration of the co-electrolysis process of NewCO2Fuels
Source httpwwwnewco2fuelscoilproduct8overview
Furthermore some companies focus on chemical or biological CO2-to-fuel production Examples of
companies that focus on direct (co-electrolysis) CO2 to fuels production are Carbon Recycling (Iceland) and
Econic (UK ndash carbon capture) The company Liquid Light (US ndash carbon capture) focuses on the
electrochemical conversion of CO2 to chemicals
Other companies involved in carbon capture are Global Thermostat (US) Quantiam (Canada) Carbon
Engineering (Canada) Evonik Industries AG (Germany) and Haldor Topsoe (Denmark) Besides co-
electrolysis Catalytic Innovations Opus 12 and Lanzatech are also involved in carbon capture Mitsui
Chemical is focusing on carbon capture as well as photoelectrocatalysis
457 Assessment of the capabilities of the industry to develop AP technologies
Although there is a lot of research activity going on in the field of AP both at the academic and industrial level
the technology is clearly not yet ready for commercialisation However concrete test facilities and prototypes
are being developed and solar fuels have already been produced at a laboratory scale The technology is not
yet sufficiently efficient in order to be able to compete with other technologies producing comparable
chemicals and fuels Finding catalysts which are on the one hand Earth-abundant non-toxic and inexpensive
and on the other hand sufficiently efficient seems to be the biggest challenge With respect to the
technological efficiency of the AP processes the main bottlenecks are light capture (whole spectrum) getting
a good photocurrent density and using these charge carriers efficiently87
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade In September 2014 Panasonic Corporation managed to achieve a conversion
efficiency rate of 03 becoming the first to exceed the rate of 02 for regular plants In November 2014
Toshiba reached 15 which was followed by 20 achieved by the Japan Technological Research
Association of Artificial Photosynthetic Chemical Process (ARPChem) in February 2015 In February 2016
Toyota Central RampD Labs Inc announced that they achieved the worldrsquos highest energy conversion
efficiency rate of 46 with artificial photosynthesis by developing a semiconductor substrates-using iridium
and ruthenium catalyst They succeeded in increasing the efficiency rate a hundred-fold (an efficiency rate of
004 had been in achieved by Toyota in 2011)88
Figure 47 summarizes these efficiency rate developments
Several companies (eg Toshiba) hint at achieving efficiency rates of 10 and the first practical applications
87
httpwwwosa-opnorghomearticlesvolume_24february_2013featuresartificial_photosynthesis_saving_solar_energy_for 88
httpswwwasiabiomassjpenglishtopics1603_01html
86
of AP in the 2020s ARPChem aims to achieve a 10 level of energy conversion efficiency in 2021 (the rate
at which the manufacturing of raw materials for chemicals becomes economically viable)89
Figure 47 Transition of energy conversion efficiency of artificial photosynthesis
Source httpswwwasiabiomassjpenglishtopics1603_01html
It can also be observed that the big industrial investors in AP technology (research) already built interesting
partnerships with research centres and new innovative start-upscompanies For example
Audi works together with the innovative company Joule Unlimited (US) on the development of biologically-
derived e-ethanol and e-diesel and also works together with start-up company Sunfire on the production
of synthetic diesel
Siemens works together with specialists at the University of Lausanne in Switzerland and at the University
of Bayreuth Germany on innovative catalysts
Royal Dutch Shell and Total are partners of the Solar Fuels Institute (SOFI) at Northwestern University
(US) that works on the water-splitting and CO2 reduction process and
Mitsubishi is one of the five industrial partners in the Japanese ARPChem programme (2012-2021)
focusing on artificial photosynthesis research in which various Japanese universities will be involved
(including Waseda University and Tokyo University)
46 Summary of results and main observations
The aim of this report was to gain an understanding and a clear overview of the main European and global
actors active in the field of artificial photosynthesis This has been achieved by
Identifying the main European and global actors active in the field of AP
Providing an assessment of the current level of investments in AP technologies
Assessing the key strengths and weaknesses of the main actors and
Assessing the capabilities of the industry to develop and exploit the AP technologies
Fuelled by the globally perceived need to find a green non-polluting and emission neutral energy source for
the future there has been much development in the field of artificial photosynthesis and considerable progress
has been made In addition the emergence of multiple consortia and governmental programmes and
international conferences in the last 10-15 years suggest that there is a higher awareness of the potential of
89
httpwwwmitsubishichem-hdcojpenglishcsrdownloadpdf13_25pdf
87
AP and that further advances are necessary The analysis has shown that although there have been some
promising developments especially in collaboration with industry much remains to be done for AP
technologies and processes to become commercially viable Milestones which will spur the development and
commercialisation process of AP encompass increased global and industry cooperation and the deployment
of targeted large-scale innovation projects following the example of the US innovation hubs
A summary of the results of the analysis and the main observations concerning the research and industry
actors active in the field of artificial photosynthesis is presented below It should be noted that the academic
and industrial community presented in this report is not exhaustive and especially with increasing interest in
AP more actors are expected to become active in the field
Research community
In general we observe that AP research has been intensified during the last decade given the increasing
number of emerging networks and communities We identified more than 150 research groups on AP
worldwide out of which more than 60 are located in Europe Due to the interdisciplinary character of AP
research combines expertise from biology biochemistry biophysics and physical chemistry The development
of research networks and consortia facilitates collaboration between different research groups and enables
them to benefit from synergies We identified six consortia in Europe and five outside of Europe respectively
Almost all of them are based in a specific country attracting primarily research groups from that country Only
one consortium AMPEA launched by the European Energy Research Alliance is truly pan-European with a
range of members across the EU
Table 415 Summary of findings size of research community
Number of research groups
Total in Europe 113
Number of research groups per pathway
Synthetic biology amp hybrid systems 53
Photoelectrocatalysis 69
Co-electrolysis 25
Total outside Europe 77
Number of research groups per pathway
Synthetic biology amp hybrid systems 30
Photoelectrocatalysis 59
Co-electrolysis 14
Source Ecorys
With respect to the three technology pathways (synthetic biology amp hybrid systems photoelectrocatalysis and
co-electrolysis) we observed that almost 85 of the research activities worldwide are focused on the first two
pathways (about 34 on the first pathway and 50 on the second) whereas the third pathway attracts only
about 16 of the research communityrsquos attention Only the Dutch AP consortium BioSolar Cells specifically
focuses on co-electrolysis Other consortia like ARPChem in Japan collaborating with industry prefer to
research artificial photosynthesis via photoelectrochemical catalysis as this pathway is the most mature and
with the highest probability of successful commercialisation
The diversity of the scientists involved is the biggest strength of this global AP research community
Furthermore all of the existing technological pathways in AP are covered which avoids lock-ins into one
pathway and increases the probability of success for AP in general AP is on the research agenda of several
countries which is proven by the existence of dedicated programmes roadmaps and funds Globally several
hundreds of millions of euros are being spent this decade on AP research and these investments seem to be
intensifying further Major shortcomings encompass a lack of cooperation between research groups in
88
academia on the one hand and between academia and industry on the other A more technical challenge is
the transfer of scientific insights into practical applications and ultimately into commercially viable products
The AP sector in Europe exhibits some strengths in comparison to its non-European counterparts but also
some weaknesses Europersquos scientific institutions are strong and its researchers highly educated
Furthermore RampD institutions and research facilities are available providing a solid ground for research
Some individual MS have their own research programmes roadmaps and funds Nevertheless the investment
does not reach the amount of funds available in some non-European countries and is rather short-term in
comparison to that of its non-European counterparts Furthermore both the national research plans and their
funding seem fragmented and scattered lacking an integrated approach with common research goals and
objectives At the European level however collaboration has been successful within several ongoing and
conducted FP7 projects Close collaboration between research groups could also be achieved through the
establishment of consortia Apart from the pan-European consortium AMPEA collaboration between research
groups of different countries is limited the consortia are primarily country-based and attract mostly research
groups from that respective country Lastly the level of collaboration between academia and industry seems
to be more limited in Europe compared to that within the US or Japan
Industrial actors
At this moment the number of companies active in the field of AP is limited AP is still mainly at the laboratory
level Most pathways are still at level 1 or 2 of technology readiness (TRL) implying that research is still being
conducted and used to improve feasibility Only co-electrolysis is at a more advanced stage and most
methods are already commercially viable
Based on our analysis of the main AP actors in the industry only several tens of companies appear to be
active in this field Moreover the industrial activity is limited to research and prototyping as viable AP
technologies are not (yet) in commercial operation The pathways synthetic biology amp hybrid systems and
photoelectrocatalysis are still at the lowest levels of technology readiness Research within the
photoelectrocatalysis pathway is still at an early stage as well however PV devices (semiconductor devices
similar to the ones used in PEC devices) have already been successfully commercialised Co-electrolysis on
the other hand is a technology already available for a longer time period in this pathway various
technologies to convert water and DC electricity into gaseous hydrogen and oxygen are already
commercialised In contrast the technologies producing hydrocarbons by Fischer-Tropsch synthesis
converting for example CO2 H2O and syngas into hydrocarbon fuels are still at an earlier stage of
development Co-electrolysis is therefore at a 1-9 TRL having both already commercialised technologies as
well as the Fischer-Tropsch synthesis
In total we have identified and analysed 33 industrial actors active in the field of AP 15 European and 18 non-
European industrial actors With respect to the industry largely the same countries stand out as in the
research field namely Japan the US and north-western Europe The industry in Japan appears to have the
most intensive research activities in AP as several large Japanese multinationals have set up their own AP
RampD laboratoriesresearch departments With respect to the three technology pathways we can observe that
most industrial (research) activity is being performed concerning photoelectrocatalysis
89
Table 416 Summary of findings size of industrial community
Number of companies
Total in Europe 15
Number of companies per pathway
Synthetic biology amp hybrid systems 6
Photoelectrocatalysis 9
Co-electrolysis 1
Total outside Europe 18
Number of companies per pathway
Synthetic biology amp hybrid systems 3
Photoelectrocatalysis 11
Co-electrolysis 5
Source Ecorys
The main hurdles in the synthetic biology amp hybrid systems pathway relate to the improvement of efficiency
and protein production speeds as well as stability and solubility by rational design With respect to the
technological efficiency of the AP processes relating to photoelectrocatalysis the main bottlenecks are light
capture (whole spectrum) obtaining a good photocurrent density and using these charge carriers efficiently
Co-electrolysis is mainly facing challenges to increase the lifetime of the devices to create concept on a
megawatt scale to search for substitution of noble metal catalysts and to develop technologies that are
capable of supplying the electricity required Furthermore some methods are still at a low TRL like the
Fischer-Tropsch synthesis Finding catalysts which are Earth-abundant non-toxic inexpensive and
sufficiently efficient remains a huge challenge To this end more public and private funding is needed
Although the achieved energy conversion efficiency rates are still low significant progress has been made
during the last decade For example between 2011 and 2016 Toyota Central RampD labs made a significant
leap forward from an efficiency rate of 004 towards an efficiency rate of 46 Furthermore several
industrial actors (including Toshiba and ARPChem) have hinted at being able to achieve efficiency rates of
10 and the first practical applications of AP in the 2020s When academia are able to overcome the main
barriers with respect to AP the TRL will increase and the interest in AP from the industries will rise More
interest from the industries is necessary in order to push AP on the market and making it an economically
viable alternative renewable energy source
91
5 Factors limiting the development of AP technology
The overall concept followed in this study is to assess a number of selected ongoing research technological
development and demonstration (RTD)initiatives andor technology approaches implemented by European
research institutions universities and industrial stakeholders in the field of AP (including the development of
AP devices)
Seven AP RTD initiatives have been identified for the assessment of ldquolimiting factorsrdquo addressing the three
overarching technology pathways synthetic biology amp hybrid systems photoelectrocatalysis of water (water
splitting) and co-electrolysis (see Table 51)
The authors are confident that through the assessment of these selected European AP RTD initiatives a good
overview of existing and future factors limiting the development of artificial photosynthesis technology (in
Europe) can be presented However it has to be noted that additional AP RTD initiatives by European
research institutions universities and industrial stakeholders do exist and that this study does not aim to prove
a fully complete inventory of all ongoing initiatives and involved stakeholders
Table 51 Overview of the selected AP research technological development and demonstration (RTD) initiatives
AP Technology
Pathways AP RTD initiatives for MCA
Synthetic biology amp
hybrid systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Biocatalytic conversion of CO2
into formic acid ndash Bio-hybrid
systems
Photoelectrocatalysis
of water (light-driven
water splitting)
Direct water splitting with bandgap absorber materials and
catalysts
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
a) Direct water splitting with III-
V semiconductor ndash Silicon
tandem absorber structures
b) Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Co-electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
Electrolysis cells for CO2
valorisation ndash Industry
research
51 Cost efficiency lifetimedurability energy efficiency and resource use challenges
Until today much progress has been made in the development of artificial photosynthetic systems
However a number of significant scientific and technological challenges remain to successfully scale-up
existing laboratory prototypes of different AP technology approaches towards a commercial scale
In order to ensure that AP technologies become an important part of the (long-term) future sustainable
European and global energy system and additionally provide high-value and low carbon chemicals for
industrial applications AP based production systems need to be
Efficient so that they utilise as much sunlight as possible to produce fuels andor chemicals The larger
the fraction of sunlight that can be converted to chemical energy the fewer materials and less land would
be needed for AP devices A target efficiency of about 10 (for AP based fuel production) is an initial goal
This is about ten times the efficiency of natural photosynthesis however it should be noted that AP
92
laboratory prototype devices with solar-to-hydrogen efficiencies of 5 and more have already been
developed
Durable so that AP systems can convert a lot of energy in their lifetime relative to the energy required for
the production and installation of the devices This is a significant challenge because some materials
degrade quickly when operated under the special conditions of illumination by discontinuous sunlight
Cost-effective meaning the raw materials needed for the production of the AP devices have to be
available at a large scale and the produced fuels andor chemicals have to be of commercial interest
Resource-efficient so that they minimise the use of rare and expensive raw materials (taking into
account trade-offs between material abundancy cost and efficiency)
Today significant improvements with respect to cost-efficiency lifetimedurability energy efficiency and
resource use are still required for all existing AP technology approaches
Table 52 provides an overview of the current and target performance for the assessed seven AP research
technological development and demonstration (RTD) initiatives within the three overarching technology
pathways of synthetic biology amp hybrid systems photoelectrocatalysis and co-electrolysis
93
Table 52 Overview of the current and target performance with respect to cost-efficiency lifetimedurability energy efficiency and resource use
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
Nitrogenase
activity wanes
within a few
days
Light energy
conversion
efficiency
gt10
(theoretical
limit ~15)
4 (PAR
utilization
efficiency) on
lab level (200 x
600 mm)
No data No data
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt100 hours
CO2 reduction
energy
efficiency (full
system) gt10
(nat PS ~1)
NA (CO2
reduction
energy
efficiency for
full system) on
lab level
No data No data
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
gt500 hours
(stability goal)
gt40 hours
Solar-to-
hydrogen
(STH)
efficiency
gt17
STH efficiency
14
Reduction of
use of noble
metal Rh
catalyst and
use of Si-
based
substrate
material
1kg Rh for
1MW
electrochem
power output
Ge substrate
(for
concentrator
systems)
Si substrate
94
AP
Technology
Pathways AP RTD Initiatives
(technology approaches)
Cost Efficiency Durability Energy Efficiency Resource Use
Target Current Target Current Target Current Target Current
Photoelectroc
atalysis of
water (light-
driven water
splitting)
Bandgap abs materials
Direct water splitting with
Bismuth Vanadate (BiVO4) -
Silicon tandem absorber
structures
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency ~9
STH efficiency
49
Reduction of
use of rare Pt
catalyst
Pt used as
counter
electrode for
H2 production
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Production
costs for H2
2-4 US$ per kg
H2
No data
gt20 years
(long term)
1000 hours
(stability goal)
gt1 hour
Solar-to-
hydrogen
(STH)
efficiency
gt10
IPCE gt90
(efficiency
goal)
IPCE (incident
photon to
electron
conversion
efficiency) of
25
Reduction of
use of rare and
expensive raw
materials
High-cost Ru-
based photo-
sensitizers
used
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
SOFC capital
cost target
400 US$kW
Comp of
synthetic fuels
with fossil fuels
No data
gt20 years
(long term)
1000 hours
(stability goal)
~50 hours
(high SOEC
cell
performance
degradation
observed)
Power-to-
Liquid system
efficiencies
(full system
incl FT)
gt70
No data No data No data
Electrolysis cells for CO2
valorisation ndash Industry
research
Comp with
fossil chemi
and fuels (eg
CO ethylene
alcohols) 650-
1200 EURMt
No data
gt20 years
(long term)
10000 hours
(stability goal)
gt1000 hours
(laboratory
performance)
System
efficiencies
(full system)
gt60-70
95 of
electricity used
to produce CO
System
efficiencies
(full system)
40
No data No data
95
52 Current TRL and future prospects of investigated AP RTD initiatives
Table 53 presents an overview of the current TRL future prospects and an estimation of future required
investments for the assessed AP research technological development and demonstration (RTD) initiatives
It should be noted that due to the focus on specific selected AP RTD initiatives the investment requirements
listed below do not represent all of the RTD activities conducted by European research institutions
universities and industrial stakeholders within the three overarching technology pathways of synthetic biology
amp hybrid systems photoelectrocatalysis and co-electrolysis
Table 53 Overview of current TRL future prospects and estimated investment needs for investigated AP RTD initiatives
AP RTD Initiatives TRL achieved (June
2016)
Future Prospects Estimated Investment
needed
Photosynthetic microbial cell
factories based on cyanobacteria
TRL 3 (pres Init)
TRL 6-8 (for direct
photobiol ethanol prod
with cyanobacteria green
algae)
2020 TRL 4 (pres Init)
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Biocatalytic conversion of CO2 into
formic acid ndash Bio-hybrid systems TRL 3 2020 TRL 4
Direct water splitting with III-V
semiconductor ndash Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 (for III-VGe
tandem structures)
TRL 3 (for III-VSi tandem
structures)
2020 TRL 5 (for III-VGe
tandem structures)
2021 TRL 5 (for III-VSi
tandem structures)
Basic RTD 5-10 Mio euro
TRL 5 5-10 Mio euro
Direct water splitting with Bismuth
Vanadate (BiVO4) - Silicon tandem
absorber structures (bandgap
absorbers)
TRL 4 2020 TRL 5
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
TRL 3 2020 TRL 4
Basic RTD applicable to
a variety of RTD fields
TRL 4 5 Mio euro
Co-electrolysis of steam and
carbon dioxide in Solid Oxide
Electrolysis Cells (SOEC)
TRL 2-3 (for co-
electrolysis of H2O
(steam) and CO2)
2020 TRL 3-4 (for co-
electrolysis of H2O
(steam) and CO2)
Electrolysis cells for CO2
valorisation ndash Industry research
TRL 4 (for RE assisted
carbon compound
production)
TRL 3 (for full synthetic
photosynthesis systems)
2020 TRL 6 (for RE
assisted carbon
compound production)
2020 TRL 5 (for full
synthetic photosynthesis
systems)
TRL 6 10-20 Mio euro
53 Knowledge and technology gaps of investigated AP RTD initiatives
At present a number of significant scientific and technological challenges remain to be addressed before
successfully being able to scale-up existing laboratory prototypes of different AP technology approaches
towards the commercial scale
Table 54 presents an overview of the identified knowledge and technology gaps focusing on the assessed
AP research technological development and demonstration (RTD) initiatives
96
Table 54 Overview of knowledge and technology gaps of investigated AP RTD initiatives
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Photosynthetic microbial cell
factories based on
cyanobacteria
Further metabolic and genetic engineering of the strains
Further engineered cyanobacterial cells with respect to increased light
harvesting capacity
Streamlined metabolism toward hydrogen production for needed electrons
proteins and energy instead of being used in competing pathways
More efficient catalysts with higher turnover rates
Simple and reliable production systems allowing higher photosynthetic
efficiencies and the use of optimal production conditions
Efficient mechanisms and systems to separate produced hydrogen from other
gases
Cheaper components of the overall system
Investigation of the effect of pH level on growth rate and hydrogen evolution
Production of other carbon-containing energy carriers such as ethanol
butanol and isoprene
Improvements of the photobioreactor design
Up-scaling of photobioreactor (from present active surface of 200 x 600 mm)
Improvement of operating stability (from present about gt100 hours)
Improvement of PAR utilisation efficiency from the present 4 to gt10
Cost reduction towards a hydrogen production price of 4 US$ per kg
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Further metabolic and genetic engineering of strains
Reduction of reactive oxygen species (ROS) which are detrimental to cell
growth
Development of biocompatible catalyst systems that are not toxic to bacteria
Development of ROS-resistant variants of bacteria
Development of hybrid systems compatible with the intermittent nature of the
solar energy source
Development of strains for CO2 reduction at low CO2 concentrations
Metabolic engineering of strains to facilitate the production of a large variety of
chemicals polymers and fuels
Enhance (product) inhibitor tolerance of strains
Further optimisation of operating conditions (eg T pH NADH concentration
ES ratio) for high CO2 conversion and increased formic acid yields
Integration of enzymes into the hydrogen evolving part of ldquobionic leafrdquo devices
Mitigation of bio-toxicity at systems level
Improvements of ldquobionic leafrdquo device design
Up-scaling of ldquobionic leafrdquo devices
Improvement of operating stability (from present about gt100 hours)
Improvement of CO2 reduction energy efficiency towards gt10
Cost reduction of the production of formic acids and other chemicals
polymers and fuels
97
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
Increased understanding of surface chemistry at electrolyte-absorber
interfaces
Further improvement of functionalization to achieve higher stabilities without
the need for protective layers
Reduction of defects acting as recombination centres or points of attack for
(photo)corrosion
Reduction of pinhole formation leading to reduced mechanical stability of the
Rh catalyst
Reduction of the amount of rare and expensive catalysts by the use of core-
shell catalyst nanoparticles with a core of an earth-abundant material
Reduction of material needed as substrate by employment of lift-off
techniques or nanostructures
Deposition of highly efficient III-V tandem absorber structures on (widely
available and cheaper) Si substrates
Development of III-V nanowire configurations promising advantages with
respect to materials use optoelectronic properties and enhanced reactive
surface area
Reduction of charge carrier losses at interfaces
Reduction of catalyst and substrate material costs
Reduction of costs for III-V tandem absorbers
Development of concentrator configurations for the III-V based
photoelectrochemical devices
Improvement of device stability from present gt40 hours towards the long-term
stability goal of gt500 hours
Improvement of the STH production efficiencies from the present 14 to
gt17
Cost reduction towards a hydrogen production price of 4 US$ per kg
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Improvements of the light absorption and carrier-separation efficiency
(currently still at lt60) in BiVO4
Better utilization of the solar spectrum by BiVO4 especially for wavelengths
close to the band edge (eg by plasmonic- andor resonance-enhanced
optical absorption)
Further development of novel water-oxidation catalysts based on for example
cobalt- and iron oxyhydroxide-based materials
Further development of the distributed n+ndashn homojunction concept for
improving carrier separation in high-donor density photoelectrode material
Improvement of the stability and avoidance of mass transport and light
scattering problems in devices based on nanoporous materials and DSSC
(Dye Sensitised Solar Cells)
Further development of Pulsed Laser Deposition (PLD) for (multi-layered)
WO3 and BiVO4 photoanodes
Although the near-neutral pH of the electrolyte solution ensures that the BiVO4
is photochemically stable proton transport is markedly slower than in strongly
alkaline or acidic electrolytes
Design of new device architectures that efficiently manage proton transport
and avoid local pH changes in near-neutral solutions
For an optimal device configuration the evolved gasses need to be
transported away efficiently without the risk of mixing
The platinum counter electrode needs to be replaced by an earth-abundant
alternative such as NiMo(Zn) CoMo or NiFeMo alloys
Improvement of device stability from present several hours towards the long-
term stability goal of 1000 hours
Scaling up systems to square meter range
Improvement of the STH production efficiencies from the present 49 to ~9
Cost reduction towards a hydrogen production price of 4 US$ per kg
Dye-sensitised
photoelectrochemical cells -
Molecular photocatalysis
Deep molecular-level understanding of the underlying interfacial charge
transfer dynamics at the SCdye catalyst interface
Novel sensitizer assemblies with long-lived charge-separated states to
Design and construction of functional DS-PECs with dye-sensitised
photoanodes and dye-sensitised photocathodes (tandem DS-PEC structures)
Design and construction of DS-PECs where undesired external bias is not
98
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
enhance quantum efficiencies
Sensitizerndashcatalyst supramolecular assembly approach appears as effective
strategy to facilitate faster intramolecular electron transfer for long-lived
charge-separated states
Optimise the co-adsorption for efficient light-harvesting and charge collection
Organometal halide perovskite compounds as novel class of light harvesters
(for absorber applications in DS-PEC)
Encapsulation of perovskite compounds to prevent the dissolution in aqueous
solutions
Semiconductor quantum dots (QDs) as suitable sensitizers for DS-PEC
Exploration of more efficient OERHER catalysts with low overpotentials
Use of a redox mediator analogous to the tyrosine-histidine pair in PSII to
accelerate dye regeneration and thus achieve an increased charge
separation lifetime
One-dimensional TiO2 nanostructures such as TiO2 nanotubes and nanorods
to improved the charge transport properties and thus charge collection
efficiencies
Exploration of alternative SC oxides with more negative CB energy levels to
match the proton reduction potential
Search for alternative more transparent p-type SCs with slower charge
recombination and high hole mobilities
Further studies on phenomena of photocurrent decay commonly observed in
DS-PECs under illumination with time largely due to the desorption andor
decomposition of the sensitizers andor the catalysts
needed
Design and construction of DS-PECs with enhanced quantum efficiency
(towards 90 IPEC)
Ensure dynamic balance between the two photoelectrodes in order to properly
match the photocurrents
Development of efficient photocathode structures
Ensure long-term durability of molecular components used in DS-PEC devices
Reduce photocurrent decay due to the desorption andor decomposition of the
sensitizers andor the catalysts
Ensure active photosensitizer and catalyst for at least millions of cycles in 20ndash
30 years
Ensure long operating lifetimes (such as achieved for DSC) for stable DS-PEC
devices that incorporate molecular components Future work on developing
robust photosensitizers and catalysts firm immobilization of sensitizercatalyst
assembly onto the surface of SC oxide as well as the integration of the robust
individual components as a whole needs to be addressed
Scaling up systems to square meter range
Improvement of the STH production efficiencies IPCE (incident photon to
electron conversion efficiency) need to be improved from ~25 to gt90
Cost reduction towards a hydrogen production price of 4 US$ per kg
99
AP RTD initiatives
(technology approaches) Knowledge gaps identified Technology gaps identified
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Basic understanding of reaction mechanisms in co-electrolysis of H2O (steam)
and CO2
Basic understanding of dynamics of adsorptiondesorption of gases on
electrodes and gas transfer during co-electrolysis
Basic understanding of material compositions microstructure and operational
conditions
Basic understanding of the relation between SOEC composition and
degradation mechanisms
Development of new improved materials for the electrolyte (eg Sr- and Mg-
doped lanthanum gallate (LSGM) and scandium-stabilized zirconia (Sc- SZ))
Development of new improved materials for the electrodes (eg Sr- and Fe-
doped lanthanumcobaltate (LSCF)Sr-doped lanthanum ferrite (LSF)Co-
and Nb-doped barium ferrite (BCFN) and Sr- and Fe-barium cobaltate
(BSCF) perovskites)
Avoidance of agglomeration of Ni-particles and micro-cracks in Ni-YSZ
hydrogen electrodes
Avoidance of mechanical damages (eg delamination of oxygen electrode) at
electrolyte-electrode interfaces
Reduction of carbon (C) formation during co-electrolysis
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Replacing metallic based electrodes by pure oxides
Studies of long-term durability
Effective utilisation of external heat sources
Up-scaling of cells for efficient co-electrolysis of H2O (steam) and CO2
Improvement of stability performance (from present ~50 hours towards the
long-term stability goal of gt1000 hours
Optimisation of operation temperature initial fuel composition and operational
voltage to adjust H2CO ratio of the syngas
Improvement of the co-electrolysis syngas production efficiencies towards
values facilitating the production of competitive synthetic fuels via FT-
processes
Cost reduction towards competitiveness of synthetic fuels with fossil fuels
Electrolysis cells for CO2
valorisation ndash Industry
research
Further research on catalyst development
Investigation of catalyst surface structure (highly reactive surfaces)
Catalyst development for a variety of carbon-based chemicals and fuels
Research on electrolyte composition and performance (dissolved salts current
density)
Research on light-collecting semiconductor grains enveloped by catalysts
Research on materials for CO2 concentration
Careful control of catalyst manufacturing process
Precise control of reaction processes
Development of modules for building facades
Stable operation of lab-scale modules
Stable operation of demonstration facility
Improvement of production efficiencies for carbon-based chemicals and fuels
Cost reduction towards competitiveness of the produced carbon-based
chemicals and fuels
100
54 Coordination of European research
Although RTD cooperation exists between universities research institutions and industry from different
European countries the majority of the activities are performed and funded on a national level Thus at
present the level of cooperation and collaboration on a pan-European level seems to be limited
There are few pan-European and cross-country initiatives such as AMPEA and partnerships under FP7
projects and many research groups that are operating locally and are funded by national governments A low
degree of collaboration among different research groups was reported which results in a duplication of efforts
and a lack of generalized standards Synergies which could potentially boost research in artificial
photosynthesis are being overlooked Creating for example a communication platform to facilitate exchange
among actors could more easily promote the development of knowledge and increase the speed of discovery
and exploitation of new robust (effective and durable) photocatalysts innovative processes and devices etc
Another indicated weakness is the lack of collaboration between the already existing and ongoing projects
The coordination of research at a European level is mainly performed by AMPEA The European Energy
Research Alliance (EERA) has launched the Joint Programme ldquoAdvanced Materials amp Processes for Energy
Applicationsrdquo (AMPEA) to foster the role of basic science in Future Emerging Technologies Artificial
photosynthesis became the first energy research subfield to be organised within AMPEA The goal of this joint
programme which was launched at the end of 2011 is to set up a thorough and systematic programme of
directed research which by 2020 will have advanced the technology to a point where commercially viable
artificial photosynthetic devices will be under development in partnership with industry
Currently AMPEA does not involve biological AP approaches as its main mission focuses on advanced
materials Therefore opportunities for research cooperation in the field of synthetic biology seem limited in the
short term
Furthermore it was stated that the current effectiveness of AMPEA to coordinate research at a European level
is limited also due to budget constraints and limited direct funding provided to AMPEA
Specifically efforts within AMPEA are currently centred on developing a concise RTD roadmap for AP
technologies in Europe The future implementation of this roadmap will require support on both national and
European levels
Table 55 (below) presents a list of European research collaborations within the investigated AP research
technological development and demonstration (RTD) initiatives
101
Table 55 (European) research cooperation within the investigated AP RTD initiatives
AP RTD Initiatives (European) Research cooperation
Photosynthetic microbial
cell factories based on
cyanobacteria
Initiative implemented by Uppsala University Sweden (within CAP) in cooperation with
Norwegian Institute of Bioeconomy Research (NIBIO)
Existing cooperation between Uppsala University and German car manufacturer VW
Biocatalytic conversion of
CO2 into formic acid ndash
Bio-hybrid systems
Initiative implemented by Wageningen UR Food amp Biobased Research and Wageningen UR
Plant Research International The Netherlands (within BioSolar Cells)
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
III-V semiconductor ndash
Silicon tandem absorber
structures
Initiative implemented by TU Ilmenau the Institute for Solar Fuels at the Helmholtz-Zentrum
Berlin and the Fraunhofer Institute for Solar Energy Systems ISE and the California Institute
of Technology (Caltech)
Existing cooperation between TU Ilmenau and epitaxy technology providers Space Solar
Power GmbH and Aixtron SE
Direct water splitting with
bandgap absorber
materials and catalysts
Direct water splitting with
Bismuth Vanadate
(BiVO4) - Silicon tandem
absorber structures
Initiative implemented by the Institute for Solar Fuels at the Helmholtz-Zentrum Berlin and
two Departments at Delft University of Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Further RTD was done at Repsol Technology Center from Spain in cooperation with
Catalonia Institute for Energy Research (IREC)
Dye-sensitised
photoelectrochemical
cells - Molecular
photocatalysis
Initiative implemented by KTH Royal Institute of Technology Sweden in cooperation with
Dalian University of Technology China (within CAP)
Further RTD at University of Amsterdam (within BioSolar Cells) University of Grenoble
University of Cambridge and EPFL (Eacutecole Polytechnique Feacutedeacuterale de Lausanne)
Existing cooperation between OMV and University of Cambridge
Existing cooperation between Siemens and EPFL
Co-electrolysis of steam
and carbon dioxide in
Solid Oxide Electrolysis
Cells (SOEC)
RTD performed at Technical University of Denmark Imperial College London University of
Sheffield and in previous years by Catalonia Institute for Energy Research (IREC) in
cooperation with Repsol Technology Center from Spain
Electrolysis cells for CO2
valorisation ndash Industry
Research
Initiative implemented by Siemens Corporate Technology (CT) in cooperation with the
University of Lausanne and the University of Bayreuth Germany
55 Industry involvement and industry gaps
Due to the low TRL (TRL 2-4) of present AP technology pathways in the areas of synthetic biology amp hybrid
systems photoelectrocatalysis of water (water splitting) and co-electrolysis the direct involvement of industry
in research and development activities in Europe is currently limited
Furthermore detailed information on industry activities in the AP field is difficult to find also due to issues of
confidentiality According to Cefic (European Chemical Industry Council) AP is regarded as a potentially
promising future technology option by the Councilrsquos members however information on industry involvement is
largely kept confidential
Several research institutions are working together in close cooperation as well as in cooperation with industrial
partners The BioSolar Cells consortium for instance has 45 industrial partners conducting research including
research in artificial photosynthesis However while companies are participating in local consortia such as
BioSolar Cells there currently seems to be a lack of cooperation between academia and industry at an
international level
102
Industry involvement in the area of synthetic biology amp hybrid systems
There is ongoing cooperation between Uppsala University and the German car manufacturer Volkswagen
within the framework of the European project ldquoPhotoFuelrdquo The project is coordinated by VW and focuses on
the production of butanol using micro-organisms
The European industry end users Volvo and VW are involved in the field of the design and engineering of
photosynthetic microbial cell factories based on cyanobacteria however are not directly involved in the
development of micro-organisms themselves
Furthermore in the USA the company Algenol Biofuels Inc is active in the field and operating a pilot scale
production unit
Industrial partners potentially interested in the development of ldquobionic leavesrdquo include the industry partners of
the Dutch BioSolar Cells programme Currently the coupling of the developed enzymes to the hydrogen-
evolving part of the device (ie the development of a full ldquobionic leafrdquo) is subject to ongoing patent procedures
by researchers of Wageningen UR
Industry involvement in the area of photoelectrocatalysis of water (water splitting)
The processes used for the deposition and processing of the devices based on two-junction tandem absorber
structures namely the metal-organic vapour phase epitaxy (MOCVD) and the in-situ functionalisation of
surfaces are generally scalable to an industrial level Spray pyrolysis processes used for the deposition of
dense thin films of BiVO4 are well-established industrial technologies and thus generally scalable to an
industrial level
Industrial stakeholders potentially interested in the area of direct water splitting with tandem absorber
structures include industry partners active in the field of epitaxy technology (eg producers and technology
providers such as Azur Space Solar Power GmbH and Aixtron SE which have ongoing long-term cooperation
with TU Ilmenau) suppliers of industrial process and specialty gases (eg Linde Group) and chemical
industries involved in catalytic processes (eg BASF Evonik)
Further interested industrial stakeholders include industry partners of the network Hydrogen Europe
(httphydrogeneuropeeu) and the Fuel Cells and Hydrogen Joint Undertaking (FCH JU
httpwwwfcheuropaeu) Hydrogen Europe (formerly known as NEW-IG) is the leading industry association
representing almost 100 companies both large and SMEs working to make hydrogen energy an everyday
reality The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) is a unique public-private partnership
supporting RTD activities in fuel cell and hydrogen energy technologies in Europe
The industry player Repsol from Spain was involved (on a research and development level) in the
development of photoelectrochemical water splitting based on metal oxides (WO3 BiVO4) through its Repsol
Technology Center in Spain in cooperation with the Department of Advanced Materials for Energy Catalonia
Institute for Energy Research (IREC) and the Department of Electronics University of Barcelona (UB) The
focus is currently centred on Pulsed Laser Deposition (PLD) for (multi-layered) WO3 and BiVO4 photoanodes
No full devices for photoelectrochemical water splitting have however yet been reported within this initiative
In the area of dye-sensitised PEC potentially interested industrial partners include the major fuel companies
Shell and Total who are already members of SOFI (Solar Fuels Institute based at Northwestern University)
an international research and innovation organisation with several European members (including the core
member Uppsala University) The Austrian fuel company OMV funds research at the Reisner Lab at the
Department of Chemistry at the University of Cambridge which is involved in both dye and catalyst
development
103
Successful technology transfer has recently been reported by Innovation Exchange Amsterdam (IXA) the
technology transfer office of the University of Amsterdam to the French company PorphyChem Rights were
licensed for the commercialisation of novel molecules for hydrogen generation so-called metalloporphyrins
innovative molecular photosensitizers which enable sustainable sunlight-driven hydrogen production from
water In cooperation with IXA the researchers filed patent applications with the European Patent Office on 26
February 2015 H-C Chen A M Brouwer Photosensitizer Europatent application 2015 EP15156740
The industry player Siemens AG from Germany is funding a project implemented by the Laboratory of
Photonics and Interfaces the Institute of Chemical Sciences and Engineering the School of Basic Sciences
and the Ecole Polytechnique Federale de Lausanne (EPFL) for the development of efficient photosynthesis of
carbon monoxide from CO2 using perovskite photovoltaics
Industry involvement in the area of co-electrolysis
Until today the involvement of industry in the research and development of the co-electrolysis of water and
carbon dioxide in Solid Oxide Electrolysis Cells (SOECs) in Europe is limited
Activities (on a research and development level) were performed by the industry player Repsol from Spain
through its Repsol Technology Center in cooperation with the Department of Advanced Materials for Energy at
the Catalonia Institute for Energy Research (IREC) The focus of these efforts is the replacement of metallic-
based electrodes by pure oxides offering advantages for industrial applications of solid oxide electrolysers
Thereby the aim is to ensure suitable H2CO ratios of the produced syngas (ie close to two) fulfilling the
basic requirements for synthetic fuel production
At present the focus of industrial engagement (eg sunfire Audi) for the production of synthetic carbon-based
fuels via concepts using (co)electrolysis and FT-processes favours water electrolysis (for the production of H2)
and the separate addition of CO2 in the FT-process over co-electrolysis of water and carbon dioxide
In April 2015 the company sunfire GmbH announced that it succeeded in producing synthetic diesel from air
water and green electrical energy A demonstration rig for power-to-liquids was inaugurated in November
2014 Recently the plant reached its full operating capacity and now produces synthetic diesel fuel Audi the
German car manufacturer and project partner of sunfire exposed the synthetic diesel to laboratory tests with
the result that the fuel was approved A larger plant needs to be developed in order to proceed towards a
commercial application of this process
An industry-driven approach towards the valorisation of carbon dioxide for the production of carbon-based
chemicals and fuels is implemented by Siemens Corporate Technology (CT) in Munich Germany This work is
implemented within the framework of the Siemens corporate project ldquoCO2toValuerdquo where catalyst
development is performed in cooperation with researchers from the University of Lausanne in Switzerland and
materials scientists at the University of Bayreuth
A small-scale lab unit based on an electrolyser cell is currently in operation at Siemens CT and a large-scale
demonstration facility is planned to be operational in the coming years in order to pave the way towards the
industrial application of this synthetic photosynthesis process for the production of carbon-based chemicals
and fuels to be introduced into the market
104
56 Technology transfer opportunities
The transfer of research to industrial application in artificial photosynthesis remains challenging In order to
attract the attention of the private sector artificial photosynthetic systems have to be cost-effective efficient
and durable The active involvement of industrial parties could help bring research prototypes to
commercialisation This step towards commercialisation requires sufficient critical mass and funding however
which cannot be borne by a single country
In the framework of the assessment of the seven AP technology approaches in the areas of synthetic biology
amp hybrid systems photoelectrocatalysis of water (water splitting) and co-electrolysis a number of ongoing
collaborations between research organisations and the industry as well as future opportunities for technology
transfer have been identified
Technology transfer opportunities in the area of synthetic biology
There are ongoing patent procedures by researchers at Wageningen UR on the coupling of developed
enzymes to the hydrogen-evolving part of the device (ie the development of a full ldquobionic leafrdquo)
Technology transfer opportunities in the area of photoelectrocatalysis of water (water splitting)
There are several patents filed by the researchers of TU Ilmenau and a patent on full device for direct
water splitting with III-V semiconductor based tandem absorber structures is under development
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC) and University of Barcelona (UB)
Successful technology transfer has been achieved by the technology transfer office of the University of
Amsterdam to the French company PorphyChem rights were licensed for the commercialisation of
metalloporphyrins as novel molecules for hydrogen generation which enable sustainable sunlight-driven
hydrogen production from water patent applications have been filed with the European Patent Office
There are technology transfer opportunities between OMV and the University of Cambridge and between
Siemens and EPFL on perovskite PV
Technology transfer opportunities in the area of co-electrolysis
There are technology transfer opportunities between Repsol and the Catalonia Institute for Energy
Research (IREC)
There are technology transfer opportunities between Siemens and the University of Lausanne as well as
the University of Bayreuth
Table 56 below provides and overview of industry involvement and technology transfer opportunities
105
Table 56 Overview of industry involvement and technology transfer opportunities
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
Synthetic
biology amp
hybrid
systems
Photosynthetic microbial cell
factories based on
cyanobacteria
Uppsala University Sweden (within
CAP) in cooperation with Norwegian
Institute of Bioeconomy Research
(NIBIO)
Existing cooperation between Uppsala University
and German car manufacturer VW
Interest by end users Volvo and VW
Biocatalytic conversion of
CO2 into formic acid ndash Bio-
hybrid systems
Wageningen UR Food amp Biobased
Research and Wageningen UR
Plant Research International The
Netherlands (within BioSolar Cells)
Industry partners of BioSolar Cells
Ongoing patent procedures by researchers of
Wageningen UR on the coupling of the developed
enzymes to the hydrogen evolving part of the
device (ie the development of a full ldquobionic leafrdquo)
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with III-V
semiconductor ndash Silicon
tandem absorber structures
TU Ilmenau Institute for Solar Fuels
at the Helmholtz-Zentrum Berlin and
the Fraunhofer Institute for Solar
Energy Systems ISE and the
California Institue of Technology
(Caltech)
Existing cooperation between TU Ilmenau and
epitaxy technology providers Space Solar Power
GmbH and Aixtron SE
Interest by suppliers of industrial gases (eg
Linde Group) and chemical industries involved
in catalytic processes (eg BASF Evonik)
Industry partners of network Hydrogen Europe
and the Fuel Cells and Hydrogen Joint
Undertaking (FCH JU)
Several patents filed by researchers of TU
Ilmenau
Patent on full device for direct water splitting with
III-V thin film based tandem absorber structures
under development
Photoelectroc
atalysis of
water (water
splitting)
Direct water splitting with
bandgap absorber materials
and catalysts Direct water
splitting with Bismuth
Vanadate (BiVO4) - Silicon
tandem absorber structures
Institute for Solar Fuels at the
Helmholtz-Zentrum Berlin two
Departments at Delft University of
Technology (within BioSolar Cells)
Further RTD at EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
Further RTD at Repsol Technology
Center from Spain in cooperation
with Catalonia Institute for Energy
Research (IREC) and University of
Barcelona (UB)
RTD by Repsol Technology Center focus is
currently placed on Pulsed Laser Deposition
(PLD) for (multi-layered) WO3 and BiVO4
photoanodes No full devices for
photoelectrochemical water splitting have
however yet been reported
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC) and University of Barcelona (UB)
Dye-sensitised
photoelectrochemical cells -
molecular photocatalysis
KTH Royal Institute of Technology
Sweden in cooperation with Dalian
University of Technology China
Existing cooperation between OMV and
University of Cambridge
Existing cooperation between Siemens and
Successful technology transfer by technology
transfer office of University of Amsterdam to the
French company PorphyChem Rights were
106
AP
Technology
Pathways
AP RTD Initiatives
(technology approaches) RTD institutions involved Industry involvedinterested Technology transfer opportunities
(within CAP)
Further RTD at University of
Amsterdam (within BioSolar Cells)
University of Grenoble University of
Cambridge and EPFL (Eacutecole
Polytechnique Feacutedeacuterale de
Lausanne)
EPFL
Industry partners of BioSolar Cells
Chemical industries involved in catalytic
processes (eg BASF Evonik)
Fuel companies Shell and Total
licensed for the commercialisation of novel
molecules for hydrogen generation so-called
metalloporphyrins innovative molecular
photosensitizers which enable sustainable
sunlight-driven hydrogen production from water
Patent applications filed with the European Patent
Office
Technology transfer opportunities between OMV
and University of Cambridge and between
Siemens and EPFL on perovskite PV
Co-
electrolysis
Co-electrolysis of steam and
carbon dioxide in Solid
Oxide Electrolysis Cells
(SOEC)
Technical University of Denmark
Imperial College London University
of Sheffield and Catalonia Institute
for Energy Research (IREC) in
cooperation with Repsol Technology
Center from Spain
RTD by Repsol Technology Center focus is the
replacement of metallic based electrodes by
pure oxides offering advantages for industrial
applications of solid oxide electrolysers
Sunfire and Audi (steam electrolysis and FT-
synthesis)
Technology transfer opportunities between Repsol
and Catalonia Institute for Energy Research
(IREC)
Electrolysis cells for CO2
valorisation ndash Industry
research
Siemens Corporate Technology (CT)
in cooperation with the University of
Lausanne and the University of
Bayreuth Germany
Industry driven approach towards the
valorisation of carbon dioxide for the production
of carbon-based chemicals and fuels by
Siemens CT
Technology transfer opportunities between
Siemens and University of Lausanne University of
Bayreuth
107
57 Regulatory conditions and societal acceptance
The current very low oil prices as well as the low carbon price (ie the fee that must be paid for the right to
emit CO2 into the atmosphere) are hindering the market uptake of the low carbon AP-based production of
chemicals polymers and fuels (carbon-based fuels as well as hydrogen) In addition until today carbon
benefits are only monetised in the energy sector and not for the production of eg low carbon chemicals
Furthermore direct market incentives for solar fuels may be an opportunity for the future development of AP
technologies In addition investments made towards the establishment of a European infrastructure for
hydrogen storage and handling may be beneficial for the future development of AP technologies
Advancements in artificial photosynthesis have the potential to radically transform how societies convert and
use energy However their successful development hinges not only on technical breakthroughs but also on
the acceptance and adoption by energy users
It is therefore important to learn from experiences with other energy technologies (eg PV wind energy
nuclear energy biofuels) and thoroughly involve all societal actors in a discussion on the potential benefits
and drawbacks of the emerging technology already during the very early stages of development
Specifically barriers to social acceptance and issues causing public concern need to be addressed in an open
dialogue and potential measures mitigating concerns need to be discussed and implemented (where
possible) It needs to be kept in mind that the majority of the public is largely unaware of AP technologies
The following main topics are subject to public concern with respect to present AP technology pathways in the
areas of synthetic biology amp hybrid systems photoelectrocatalysis of water (water splitting) and co-
electrolysis
The use of genetic engineering and Genetically Modified Organisms (GMO) mainly for synthetic biology
approaches
The use of toxic materials for the production of AP devices which concerns all pathways
The use of rare and expensive raw materials for catalysts and absorber materials also for all pathways
Land use requirements for large-scale deployment of AP technology and land use competition with other
renewable energy options such as PV solar thermal applications and bioenergybiofuels
High societal costs involved in the development of AP technologies (efficiency and competitiveness of AP
technologies)
The importance of societal dialogue within the future development of AP technologies is widely acknowledged
within several national initiatives in Europe Initiatives on public involvement are implemented within the Dutch
BioSolar Cells programme and by the German National Academy of Science and Engineering (acatech)
109
6 Development roadmap
61 Context
611 General situation and conditions for the development of AP
Current energy technologies are unlikely to be sufficient to attain EU ndash and other international ndash long term
targets for the share of renewable energy sources in overall energy supplies beyond 2020 There is therefore
a strategic interest in supporting efforts to develop new energy technologies (and improve existing ones) and
to raise their competitiveness ndash eg in terms of costs efficiency and resource use ndash vis-agrave-vis those that are
currently available Thus from an energy policy perspective the motivation for accelerating the industrial
implementation of AP technologies arises from their potential to expand the available portfolio of competitive
sustainable energy sources thereby contributing to the continuation of the transition away from fossil fuels At
the same time from the perspective of growth and job creation developing and demonstrating the viability and
readiness for industrial deployment of AP technologies can be viewed as part of a wider industrial policy to
develop an internationally competitive European renewable energy technology industry
Processes based on AP have been identified as having the potential to deliver sustainable alternatives to
conventional fuels AP-based lsquowater-splittingrsquo processes may be used for the production of hydrogen or in
combination with lsquocarbon reductionrsquo for the production of carbon-based fuels (lsquosolar fuelsrsquo) and other higher
order carbon-based compounds However although AP technologies show great potential and despite the
significant progress in research in the AP field made in recent years there is still a significant way to go before
AP technologies are ready for industrial implementation
AP covers several technology pathways that are being developed in parallel and which are all at a low overall
level of technology readiness The individual processes sub-systems and components within the different
pathways are however at varying levels of maturity Consequently it is difficult to foresee the eventual
production efficiency costs and material requirements that could characterise future AP-based systems when
implemented on an industrial scale Moreover while it is possible that some AP technologies may end up
competing with each other complementarities and synergies may arise from AP technology development
activities that are currently being conducted largely in isolation from each other
To date application of AP has only been undertaken in small scale in laboratory conditions and the feasibility
of commercial industrial-scale deployment of AP systems has yet to be demonstrated Assuming that this can
be achieved at cost levels that enable AP-based products to be competitive in the marketplace commercial
implementation may raise some more practical issues for example in relation to land-use water availability
and other possible environmental or social concerns that have not as yet been fully explored
To appreciate the possible future role of AP technologies also requires consideration of other developments
shaping the energy supply and technology landscape Although by definition AP is concerned with the direct
conversion of solar energy into fuel technologies for specific processes developed within the context of AP
may eventually be linked to other renewable energy technologies for example if they are combined with
electricity generated from photovoltaics (PV) or other renewable sources such as wind energy Similarly the
production of lsquosolar fuelsrsquo using AP systems requires a source of carbon which may come in the form of CO2
from ambient air or alternatively by linking AP to carbon capture (and storage) systems90
90
See for example DG Research (2015) ldquoProceedings of the scoping workshop Transforming CO2 into value for a rejuvenated European economy Brussels 26th March 2015rdquo
110
Prospects for the future industrial implementation of AP technologies will not only depend on the lsquopushrsquo
provided by technological developments but will also depend on market lsquopullrsquo factors Not least the
commercial viability of fuels produced using AP technologies (and other renewable energy sources) will be
strongly influenced by price developments for other fuels particularly oil Current low oil and carbon
(emissions) prices must be taken into consideration as factors potentially hindering the market uptake of low
carbon AP-based production of chemicals polymers and fuels (including hydrogen) both now and in the
future
The overall market potential of solar fuels will also depend on public policy developments for example in
terms of regulatory frameworks and incentives affecting demand levels and costsprices of renewable energy
sources Similarly a concerted policy framework targeted towards promotion of a lsquohydrogen economyrsquo may
lead to a shift in emphasis for AP technology development towards hydrogen production (lsquowater splittingrsquo) ndash
already the more advanced area of AP research ndash and away from solar fuels Certainly until a higher
technology readiness level of AP is attained care should be taken to ensure that regulatory measures ndash
whether at European and national levels ndash do not impinge upon or hinder developments along the different AP
pathways
Finally in order to truly accelerate the industrial implementation of AP social acceptance and adoption of the
new technology by energy users must be acquired As it stands the majority of the public is largely unaware
of the development and significance of AP while those who are voice concerns about genetic engineering the
use of toxic materials the use of rare and expensive raw materials and the high societal costs involved in the
development along all technology pathways
612 Situation of the European AP research and technology base
Europersquos scientific communities form more than 60 of the 150 or so research groups on AP worldwide
boasting well-educated researchers and a diverse range of scientists - an interdisciplinary approach being
crucial for scientific advancement within this highly innovative field Together these groups cover all of the
identified existing technological pathways along which the advancement of AP might accelerate thus
increasing the likelihood of cooperation between European scientists with possible breakthroughs on any
given path
Significant improvements are still needed with respect to cost-efficiency lifetimedurability energy efficiency
and resource use for all existing AP technologies and progress is being made in addressing these knowledge
and technology gaps Yet while this technological development making strides along multiple pathways
simultaneously shows a considerable amount of potential the scientific community alone cannot accelerate
the development of the industrial implementation of AP Aiding the development from a currently low
technology readiness level and eventually commercialising AP will involve a host of enabling factors
including those of the financial structural regulatory and social nature
As it stands currently European investment into AP technologies falls short of the amounts being dedicated in
a number of non-European countries and it could be argued is rather short-term if not short-sighted Further
stifling the potential of these technologies is the fact ndash significant considering most European research activity
into AP operates at a national level (only one of the six consortia in Europe being pan-European) ndash that both
national research plans and their funding are fragmented lacking a necessary integrated approach Adding to
this fragmentation there appears to be a lack of cooperation between research groups and academia on the
one hand and between academia and industry on the other This suggests that there are some structural
barriers impeding the speed and success of the development and eventual commercialisation of AP in
Europe
111
Accelerating the development of AP requires bringing the best and brightest to the forefront of the research
being carried out in the field which would in turn involve a conscious effort to boost collaboration of the top
contributors across Europe - such an effort has been the cluster of several FP7 projects the good example of
which may well serve as a foundation on which to build in the future Once the divide between research
groups and academia has been breached and the technological advancement of AP technologies has been
given the push needed to be able to climb higher up the TRL scale interest from and in turn collaboration with
the industry should rise
62 Roadmap overview
The assessment of the existing lsquostate of the artrsquo undertaken for this study reveals that AP technologies are in
general currently at relatively low levels of technology readiness levels91
There are many outstanding gaps in
fundamental knowledge and technology that must be addressed before AP can attain the level of development
necessary for industrial scale implementation Moreover there is not as yet any compelling evidence to
suggest that any particular AP pathway or sub-approach therein can currently be identified as clearly lsquomore
promisingrsquo than another Given this situation it seems appropriate at least for the time being to adopt an
lsquoopenrsquo approach to possible support measures for AP-related research efforts which does not single out and
prioritise any specific AP pathway or sub-approach This conclusion corresponds to the broad consensus view
expressed by participants at the workshop on lsquoArtificial Photosynthesis in Horizon 2020rsquo held in May 2016
Notwithstanding the above assessment if AP is to establish a role in the overall portfolio of energy sources
then the longer-term objective must be to develop competitive and sustainable AP technologies that can be
implemented at an industrial scale Thus a technology development roadmap for AP must support the
transition from fundamental research and laboratory-based validation through to demonstration at a
commercial or near commercial scale and ultimately industrial replication within the market Upscaling of
technologies and integration of processes in a complete lsquovalue chainrsquo ie from light harvesting through to
solar fuel (and other AP-based products) will require greater levels of investment and inevitably will imply
making choices on which technology options to prioritise As the general aim (of the roadmap) is to accelerate
industrial implementation these choices should reflect market opportunities for commercial application of AP
technologies while bearing in mind the overarching policy objectives of increasing the share of renewable
energy sources in overall energy supplies
621 Knowledge and technology development
Following from the above in terms of knowledge and technology development activities the outline roadmap
for support for the development of AP technologies consists of three phases as illustrated in Figure 61 and
described in more detail in the following sub-sections
91
Although the situation of with respect to different process varies most are assessed to be only at TRL 3 or 4 (ie corresponding to lsquoexperimental proof of conceptrsquo or lsquotechnology validated in labrsquo)
112
Figure 61 General development roadmap visualisation
Phase 1 Phase 3Phase 2
Regional MS amp EU
Regional MS EU amp Private
Private amp EU
Private (companies)
FUNDINGSOURCE
TRL 9Industrial
Implementation
TRL 6-8Demonstrator
Projects
Pilot ProjectsTRL 3-6
TRL 1-3Fundamental
Research
RampDampI ACTIVITIES
2017 2025 2035
113
In the following description for convenience the timeline for activities is addressed in three distinct phases It
should be noted however that some AP technologies are more advanced than others and that they
accordingly could already be at or close to readiness for pilot projects (addressed under Phase 2)
Accordingly some laboratory-based validation (TRL 4) and lsquorelevant environmentrsquo validation projects (TRL 5)
may be envisaged within Phase 1 of the Roadmap Conversely as all fundamental knowledge and technology
issues will be not be solved within the 5-7 year time horizon foreseen for Phase 1 the need to support such
development through smaller scale research projects can be expected to continue into Phase 2 of the
Roadmap and possibly beyond
Furthermore in addition to support for fundamental knowledge and technology development the Roadmap
foresees the need to integrate lsquosupporting and accompanying activitiesrsquo (see Section 622) These activities
should run in parallel to the support for knowledge and technology development with initial activities starting
within Phase 1 of the Roadmap and continuing throughout the entire period of the Roadmap It may be
appropriate that some of the suggested activity areas are addressed as part of the proposed Networking
action (Action 2) and Coordinating action (Action 5)
Phase 1 - Time horizon short term (from now to year 5-7)
This phase will target the continuation of early stage research on AP technologies in parallel with initiation of
the process of scaling-up from laboratory based bench-scale projects towards pilot scale projects (ie to
validate whether bench scale projects are viable at a pilot scale) In keeping with the general status of AP
knowledge and technology development the scope of support during this phase should remain lsquoopenrsquo to all
existing (and potential) AP technology pathways and sub-options therein Such an approach should allow for
continued long-term advances in underpinning rsquogenericrsquo scientific knowledge that may lead to a breakthrough
in terms of newnovel approaches for AP while at the same time pushing forward towards addressing
technology challenges across the broad spectrum of AP pathwaysapproaches Notwithstanding this lsquoopenrsquo
approach eventual support may be directed towards specific topics that have been identified as areas where
additional effort is required to address existing knowledge and technology gaps
Under Phase 1 possible EU funding support should a priori be directed towards multiple small scale projects
(eg euro 3-5 million) that can complement existing regional and national programmes (and existing related EU-
level support)
Phase 1 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 1)
Recommendation Support for multiple small AP research projects
Objective To address outstanding gaps in fundamental knowledge and technology relating to AP
Rationale There are many remaining outstanding gaps in AP-relevant fundamental knowledge and
technology that must be addressed before AP systems can attain the level of development
necessary for industrial scale implementation This requires continued efforts dealing with
fundamental knowledge aspects of AP processes together with development of necessary
technology for the application of AP
Resources needed Project funding indicative cost circa euro 3-5 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact Strengthen diversify and accelerate knowledge and technology development for
processesdevices for AP-based production of hydrogen (water splitting) and carbon-based lsquosolar
fuelsrsquo
Priority
High
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
114
Recommendations to support knowledge and technology development (Action 2)
Recommendation Support for enhanced networking for AP research and technology development
Objective To improve information exchange cooperation and collaboration so as to increase efficiency and
accelerate AP-relevant knowledge and technology development towards industrial scale
implementation
Rationale AP research and technology development requires expertise across multiple and diverse
scientific areas both theoretical and applied Notwithstanding existing efforts to support and
enhance European AP research networks (eg AMPEA and precursors) AP research efforts in
the EU are fragmented being to a large extent organised and funded at national levels Further
development of EU-wide (and globally integrated) network(s) would promote coordination and
cooperation of research efforts within the AP field and in related fields addressing scientific
issues of common interest This action ndash offering secure funding for networking activities at a
pan-European level ndash should raise collaboration and increase synergies that potentially are being
currently overlooked
The broader international dimension of AP research and technology development could also be
addressed under this action In particular to develop instruments to facilitate research
partnerships beyond the EU (eg with US Japan Canada etc)
Resources needed Network funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities
Funding recipients Research and technology development institutions
Expected impact By providing a platform for knowledge exchange the speed of discovery and exploitation of
knowledge and technology developments should be accelerated both within the research
community and with industry
Priority
Medium
Suggested date of implementation
Short (Phase 1) with possibility to extend implementation over
medium and long term
Recommendations to support knowledge and technology development (Action 3)
Recommendation AP Inducement Prize
Objective To provide additional stimulus for research technology development and innovation in the field
of AP while also raising awareness amongst the public and other stakeholders
Rationale The inducement prize would a priori target ldquoproof of conceptrdquo of AP at a bench-scale that meet
eligibility and award criteria set for the prize Experience suggests that lsquoinducement prizersquo
schemes can be particularly effective in situations corresponding to those of AP (ie where there
are a number of competing emergent technologies in the TRL 2-4 range that can potentially
deliver similar outcomes) The prize should provide an incentive for researchers to accelerate AP
RampD efforts and also potentially extend interest beyond the current AP research base to a wider
range of potential researchersinnovators
Resources needed Financial prize circa euro3 million
Prize organisation etc euro03 million
Actors involved Funding sources EU possible national (MS) contribution
Potential prize recipients Research and technology development institutions and (possibly)
industry
Expected impact Increased research intensity and wider participation resulting in turn to sooner than otherwise
demonstration of bench-scale AP devices This should provide for an earlier transition from
laboratory based research towards pilot projects
Priority
Medium
Suggested date of implementation92
Short (Phase 1)
92
Based on views gathered by the study there appears to be a general consensus that 3-4 years could be sufficient for the inducement prize contest timeframe Extending the timeframe for a longer period risks prize fatigue where contestants lose sight of the original prize aim and interest can start to wane
115
Phase 1 - Milestones
The scope of knowledge and technology development activities envisaged under Phase 1 is potentially very
broad as it covers multiple lsquopathwaysrsquo and a wide array of challengesissues ranging from general to highly
specific These concern each of the main AP steps (eg light harvesting charge separation water splitting
and fuel production) and range from materials issues device design and supporting activities such as process
modelling In general terms key criteria for evaluating overall progress towards the ultimate objective of
commercial implementation will revolve around factors such as efficiency of conversion of light into solar fuels
alongside the durability and potential cost-effectiveness of AP systems Shorter-term targets (lsquomilestonesrsquo)
could be set for minimum performance levels in terms of conversion efficiency (eg 10 conversion of solar
energy to hydrogen or to carbon-based fuels) although given the variation in progress across AP pathways
variable efficiency targets for individual pathways would seem appropriate
However if the purpose of the milestone is to mark the point of transition from Phase 1 to Phase 2 of the
Roadmap then a pragmatic milestone may be defined in terms of the development of an AP devicesystem
able to produce a lsquouseablersquo quantity of solar fuel in laboratory conditions sufficient to warrant further
development towards a pilot projectplant (Phase 2) In this regard it may make sense to a greater or lesser
degree to align the milestones for Phase 1 to the award criteria retained for the proposed inducement prize
Phase 2 - Time horizon medium term (from year 5-7 to year 10-12)
This phase will focus on reinforcing the implementation of pilot scale projects while initiating the process of
scaling up to a demonstration scale The scope of eventual support should focus on a limited number of
projects for the most promising AP technologies in order to demonstrate their viability at a pilot scale In this
context public (EU) funding support should be directed towards a limited number of medium scale projects At
the same time there should be encouragement of private sector participation in technology development
projects
Phase 2 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 4)
Recommendation Support for AP pilot projects
Objective To develop AP devices and integrated systems moving from laboratory scale up to an
(industrial) relevant scale of production This should enable comparative assessment of different
AP technology approaches at a production scale permitting industrial actors to make a
meaningful assessment of their potential viability for commercial deployment Equally these
projects should serve to identify (priority) areas where additional knowledge and technology
development is required in order to achieve industrial scale implementation
Rationale To reach industrial implementation of AP the feasibility of upscaling from laboratory conditions to
those approaching actual operational conditions needs to be demonstrated Accordingly pilot
projects under this Action item should provide for the testing and evaluation of AP devices to
assess and demonstrate the feasibility of reaching necessary characteristics (eg efficiency
levelstargets durabilitylife-cycle cost effectiveness) for commercial application for the
production of solar fuels The implementation of flexible pilot plants with open access to
researchers and companies should support (accelerated) development of manufacturing
capabilities for AP devices and scaling-up of AP production processes and product supply
Resources needed Project funding indicative cost circa euro 5-10 million per individual project
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Strengthen and accelerate knowledge and technology development for processesdevices for
AP-based production of hydrogen (water splitting) and carbon-based lsquosolar fuelsrsquo
Priority
High
Suggested date of implementation
Medium (Phase 2)
116
Recommendations to support knowledge and technology development (Action 5)
Recommendation Support for AP coordination
Objective To enhance efficiency (and effectiveness) of AP research efforts and more broadly to raise
coordination in the fields of solar fuels and energy technology development
Rationale There is a general need to ensure that research budgets are used effectively and to avoid
duplication of research effort In the context of AP there is a need to identify lsquomost promisingrsquo
technologies and set common priorities accordingly Moving to a common European AP
technology development strategy will require inter alia alignment of national research efforts in
the EU and (possible) cooperation at a broader international level Equally with the aim of
accelerating industrial implementation of AP there is a need to ensure cooperation and
coordination between research and technology development activities among the lsquoresearch
communityrsquo and industry
Resources needed Networkcoordination funding circa euro1-2 million
Actors involved Funding sources EU national (MS) and regional authorities possible industry support
Funding recipients Research and technology development institutions industry
Expected impact Improved coordination of AP research activities at European level (and possibly international
level) and improved priority setting to address knowledge and technology gaps for AP-based
processes and products
Priority
High
Suggested date of implementation
Medium (Phase 2) with possibility to extend implementation over
long term
Phase 2 - Milestones
The purpose of the AP pilot projects proposed under Phase 2 is inter alia to develop AP production
devicessystems operating at a sufficient scale to assess their potential viability for commercial deployment
Thus AP devicessystems developed within the pilot projects should attain sufficient performance levels and
fulfil basic operational and other characteristics (eg conversion efficiency lifetimedurability
sustainabilityresource use and cost-effectiveness) that are sufficient to attract the potential interest of private
sector (industry) investors Specific milestones for AP pilot projects may therefore be set in terms of multiple
target technical performance requirements but the overarching target lsquomilestonersquo for pilot projects will relate to
the overall assessment of their potential economic (commercial) viability conditional on further technological
developments (including engineering) and subject to their potential to comply with sustainability and other
social requirements
As a bottom line in terms of marking the point of transition from Phase 2 to Phase 3 of the Roadmap the test
for a lsquosuccessfulrsquo pilot project will be reflected in developing technology solutions able to attract private
investors willing to commit to their next stage of development either through a demonstration project (Phase
3) or directly to industrial implementation (lsquoearlyrsquo commercial projects)
Phase 3 - Time horizon long term (from year 10-12 to year 15-17)
This phase will focus of the development of ndash one or more ndash demonstration projects to assess the viability of
AP technologies at an industrial scale and facilitating the transfer of AP-based production systems from
demonstration stage into industrial production for lsquofirstrsquo markets The scope of eventual support should focus
on the AP technologies identified as most viable for commercialindustrial application However demonstration
level products should be led by the private sector ndash reflecting the need to assess commercial viability of
technologies ndash with co-funding provided by the public sector ndash reflecting the risk and large financial burden of
investments in such projects
117
Phase 3 - Recommendations (specific actions)
Recommendations to support knowledge and technology development (Action 6)
Recommendation Support for AP demonstrator projects
Objective To develop one or more demonstrator projects to assess the viability of AP technologies at a
close-to industrial scale (ie the project should be of a sufficient size to serve as a platform and
facilitating the transfer of AP-based production systems from demonstration stage into industrial
production for lsquofirstrsquo markets)
Rationale The demonstration project(s) provide a lsquostepping stonersquo between pilot projects and industrial
implementation The projects should not only provide validation of AP devices and systems but
also allow for developing and evaluating the integration of the full AP value chain93
By
demonstration the (commercial) viability of AP the project(s) should promote full industrial
investments that might otherwise be discouraged by the high cost and risk94
At the same time
beyond addressing technological and operational issues the demonstration projects should
address all other aspects ndash eg societalpolitical environmentalsustainability
economiccommercialfinancial legalregulatory geographic etc ndash necessary to evaluate how
AP based production of solar fuels could be implemented in practice
Resources needed To be determined
[Indicative budget envelope circa euro10-20 million per individual project However required funding
will depend on size and ambition of the project and may significantly exceed this amount]
Actors involved Funding sources Industry with EU support
Funding recipients Research and technology development institutions industry
Expected impact The projects should both build investor confidence in the commercial application of AP-based
solar fuel technologies and raise public confidence including in terms of safety and reliability
Priority
Medium
Suggested date of implementation
Long (Phase 3)
Phase 3 - Milestones
Given that the primary purpose of the demonstrator projects is to assess the viability of AP technologies at a
close-to industrial scale an initial milestone for such projects would be for the plants to be operational and to
be able to produce solar fuels in commercially significant volumes Ultimately the target lsquomilestonersquo will be to
produce solar fuels that are cost-competitive under actual market conditions and commercial requirements
while complying with other key requirements (eg safety societal acceptance etc)
622 Supporting and accompanying activities
The technological development of AP will throughout its various phases be guided by regulatory and market
measures as well as the degree of social acceptance In order to help secure favourable conditions for the
development and eventual commercialisation of AP technologies support will need to be provided from a very
early stage onwards within both of these spheres The prices of competing fuels and carbon emissions may
need to be regulated as well as incentives affecting the demand for renewable energy sources introduced
while the breadth of technological development regarding AP should not be hindered by regulation within the
current phase of research nor research into an eventual shift to a lsquohydrogen economyrsquo be put on the back
burner Thorough involvement of all societal actors in education and open debate regarding the potential
benefits and drawbacks of AP technologies as well as barriers to social acceptance and issues raising public
concern is also required At the same time the economic and commercial aspects of AP production
technologies and AP-produced solar fuels need to be understood including in terms of the development of
successful business models and the competitiveness of European industry in the field of AP and renewable
energy more generally
93
Where this covers the whole AP supplyvalue chain from upstream supply (eg materials components etc) to downstream demand (markets)
94 For example high cost resulting from accelerated investments to scale-up to industrial scale and high-risk profile resulting from uncertainty over which AP technologies may prove most successful together with uncertainty over operating costs and future market prices and demand for solar fuels etc These factors may otherwise discourage investments in (initial) full scale projects unless some public support is provided
118
There is potentially a wide range of themes ndash beyond purely technological and operational aspects ndash which
require to be better understood and which may be addressed through supporting and accompanying activities
including the following (non-exhaustive) topics
Industry engagement and technology transfer As far as can be ascertained the engagement of
industry in the field of AP technologies has to date been limited although because of its commercial
sensitivity it is difficult to obtain a clear picture of industrycompaniesrsquo interest in AP Nonetheless there is
a general view that a greater engagement of the industry would be beneficial for the development of AP
technologies and will become increasingly important as technologies reach higher TRLs and move closer
to commercial implementation An active involvement of industrial players in cooperative research projects
could facilitate the transfer of technology from the research community to industry (or vice versa) thereby
helping speed up the evolution from research prototypes and pilots to commercial implementation
Intellectual property protection To ensure future development and industrial application European
intellectual property in the area of AP should be adequately protected through patents At the same time
worldwide developments in AP-related patent-protected technologies should be taken into consideration
to ensure that Europe avoids potentially damaging dependences on non-European technologies
Regulatory conditions and support measures As a minimum AP technologies and products entering
the market should face a legal and regulatory environment that does not discriminate against their use and
provides a level playing field compared to other energyfuel types Beyond this there may be a public
policy justification (eg reflecting positive externalities of AP) for creating a specifically favourable
regulatory and legal framework to encourage the take-up and diffusion of AP technologies and products
At the same time other actions for example AP project financing support may be implemented to support
the industryrsquos AP investments these may be both for production investments but also for downstream
users faced by high switching costs (eg from fossil to solar fuels)
Societal aspects and safety AP technologies may potentially raise a number of public concerns that
need to be understood and addressed These may relate to safety aspects of the production storage
distribution and consumption of AP-based products for example there may be concern over the use of
genetically modified organisms (GMOs) in synthetichybrid AP processes Other areas of concern may
arise for example in relation to land use requirements or use of rare materials etc In general both
among the general public and even within the industry there is limited knowledge of AP Accordingly it
may be appropriatenecessary to implement activities to raise public and industry awareness of AP
Market potential relating to the assessment of the potential role and integration of AP energy supply and
demand Here multiple scenarios are possible for example depending on whether advances in AP
technology are targeted towards production of hydrocarbons or of hydrogen The former would require
fewer changes in terms of supporting infrastructure development (eg for fuel storage and distribution) but
is currently lagging behind in terms of AP technological development For the latter future market potential
will depend on the evolution towards a greater adoption of hydrogen-based fuel technologies Better
understanding of the shape and direction of market developments both within the EU and globally will be
important for assessing which AP technology developments offer the best prospects for future industrial
implementation At the same time the sensitivity of future prospects for AP technologies and products to
developments in the costs and market prices of competing (fossil and renewable) fuels should be
assessed
Industry organisation and business development relating to the assessment of future industrial
organisation of AP-technology production including the full supplyvalue chain for solar fuels (ie from
upstream supply of materials components equipment etc through fuel production to downstream market
supply including storage and distribution) Such an assessment will be required to better understand the
potential position and opportunities for the European industry in the area of AP which should also take
account of the business models and strategies for European players within the market
119
The aforementioned topics illustrate the diversity of the dimensions surrounding AP that require to be better
understood In a first instance more detailed economic legalregulatory social and other analyses of these
topics is warranted In turn this may lead to the formulation of more concrete policies and actions to develop
appropriate regulatory frameworks and to shape other market and business conditions in order to ensure a
supportive environment for the development and implementation of AP technologies and products
121
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Bakkers E P Notten P H Nano letters 2014 14 3715
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