Sustainable Energy

And Low Carbon Development

Lecture n. 5PLANNING FOR ENERGY:Energy Infrastructure

Pietro Zambelli

Content

Renewable Energy

Energy storage system

Efficiency

Renewable Energy

• Overview

• Renewable Energy Sources (RES)

• Why renewable energy?

• ‘Hard’ vs ‘Soft’ Energy Paths

• Role of Local and National Government In

promoting % RE

• Seven Steps To Achieve 100%: The Urban

Renewable Power Policy Toolbox

Overview

Renewable Energy

• Modern cities are, above all else, the product of fossil fuel technology.

• Could they exist and thrive, without the routine use of oil, gas and coal?

• What can be done to minimize their climate impacts and to maximize their

use of renewable energy?

Renewable Energy Sources

Renewable Energy

• Fossil fuels (Oil, Gas)

• Nuclear fuels• Solar energy, Solar heating

(passive and active), solar power

plants, photovoltaic cells

• Biomass energy, Direct:

combustion of biomass, Indirect:

chemical conversion to biofuel

• Wind energy

• Hydro energy

• Geothermal energy, Power plants,

direct use, heat pumps

• Ocean energy, Tidal; salinity-

driven

Renewable energy is generally defined as energy that is collected from

resources which are naturally replenished on a human timescale, namely

wind, solar, aerothermal, geothermal, hydrothermal and ocean energy,

hydropower, biomass, landfill gas, sewage treatment plant gas and biogases

(DIRECTIVE 2009/28/EC)

Why Renewables Energy?

Renewable Energy

• Do not deplete natural resources

• Global warming has hit the public (and

political?) conscience

• Effective method to reduce CO2 emissions

• Guarantee Energy security for countries

deploying it

• Legislation being passed making renewables

more attractive

‘Hard’ vs ‘Soft’ Energy Paths

Renewable Energy

HARD SOFT

Big plants / Centralized Small plants / Decentralized

Role of Local/National Government in Promoting % RE

Renewable Energy

Source: Droege 2010

LOCAL GOVERNMENT NATIONAL GOVERNMENT

1. Strong and enlightened Renewable

Energy Policy- e.g. solar ordinance of

the city of Barcelona (Droege, 2008).

2. Strong individual leadership (civic and

administrative) within the technical team

of the city.

3. Establishing financing scheme for RES

installations.

4. Address stakeholder’s needs and build

on local strengths

5. Create mutual benefits (economic and

environment).

6. Long-term planning

7. Encourage innovation through Research

and development

1. As a first step, National Commissions of

Inquiry should be set up to assess

framework conditions, and to propose

and support effective urban agendas

and funding programs.

2. Not to engage in policies that harm

cities' quest for 100 percent renewable

status.

3. To embrace feed-in legislation, the most

effective path to rapid local RE uptake.

4. To enact legislation supporting RE

development at regional and national

levels to supplement urban efforts.

Seven Steps To Achieve 100%

Renewable Energy

The Urban Renewable Power Policy Toolbox

1. Regulation, legislation and standards

2. Incentives and disincentives

3. Corporate asset development and management

4. Institutional reform

5. Improved strategic and general planning practices

6. Community action, industry alliances, information and

education

7. Fostering energy autonomy and biological carbon

sequestration practice

Solar energy

a. What is solar energy?

b. Breakdown of incoming solar energy

c. Using solar energy to provide heat

d. Using solar energy to provide high temperature heat

electricity

e. Solar Thermal Energy

f. Strengths and Weakness

g. Market and global overview

What is solar energy?

Solar energy

Originates with the

thermonuclear fusion

reactions occurring in the

sun.

Represents the entire

electromagnetic radiation

(visible light, infrared,

ultraviolet, x-rays, and

radio waves).

Breakdown of Incoming Solar Energy

Solar energy

http://en.wikipedia.org/wiki/File:Breakdown_of_the_incoming_solar_energy.svg

Using solar energy to provide heat

Solar energy

Passive solar heating Active solar heating

Using solar energy to provide: High-Temp Heat & Electricity

Solar energy

• Solar thermal systems

• Photovoltaic (PV) cells

Solar Thermal Energy

Solar energy

• Solar thermal electric energy generation concentrates the light from the sun to create heat,

and that heat is used to run a heat engine, which turns a generator to make electricity.

• The working fluid that is heated by the concentrated sunlight can be a liquid or a gas.

• Different working fluids include water, oil, salts, air, nitrogen, helium, etc. Different engine

types include steam engines, gas turbines, Stirling engines, etc.

Sun’s infrared rays are concentrated

through reflecting mirrors on a heating fluid

(normally liquid salt) medium, which in turn

generates steam to propel turbines

Solar Thermal Power Plants, Spain REEEP / UNIDO; 2006

PV Systems: Strengths & Weaknesses

Solar energy

Strengths Weaknesses

Technology is mature. It has high reliability and long lifetimes (power output warranties from PV panels now commonly for 25 years)

Performance is dependent on sunshine levels and local weather conditions

Automatic operation with very low maintenance requirements

Storage/back-up usually required due to fluctuating nature of sunshine levels/no power production at night

No fuel required (no additional costs for fuel nor delivery logistics)

High capital/initial investment costs

Modular nature of PV allows for a complete range of system sizes as application dictates

Specific training and infrastructure needs

Environmental impact low compared with conventional energy sources

Energy intensity of silicon production for PV solar cells

The solar system is an easily visible sign of a high level of responsibility, environmental awareness and commitment

Provision for collection of batteries and facilities to recycle batteries are necessary

The user is less effected by rising prices for other energy sources

Use of toxic materials in some PV panels

REEEP / UNIDO; 2006

Key Trends & Players

Solar energy

Beyond 2009, Photovoltaic Markets Are Expected to See Healthy Growth

Source: BCG Analysis

Global Cumulative PV Power

Solar energy

Source: http://www.epia.org/fileadmin/EPIA_docs/publications/epia/Global_Market_Outlook_Until_2013.pdf

Global Annual PV Market

Solar energy

Source: http://www.epia.org/fileadmin/EPIA_docs/publications/epia/Global_Market_Outlook_Until_2013.pdf

Cost Projections

Solar energy

Source: www.epia.org EPIA Solar Generation V Report Sept 08

$1.35

$1.07

$0.81

$0.54

$0.27

$0.13 ---

$/kWh

“Grid parity’ where PV cost

are equal to residential

electricity costs is expected

to be achieved first in

southern European countries

and then to move north

Wind energy

• What is wind energy

• Applications

• Potential Impacts and Issues

• Wind turbines

• Strengths and Weaknesses

• Market and global overview

What is wind energy

Wind power

Source: Global Wind Energy Council, Global Wind Energy Outlook 2014

Applications

Wind power

Wind turbines technology generally

falls into two categories: small, or

distributed turbines that provide

power directly to their owner, and

large, or utility-scale turbines that

provide wholesale power.

REEEP / UNIDO; 2006

Potential Impacts and Issues

Wind power

REEEP / UNIDO; 2006

Property Value

Visual Impact

Land use

and

Wildlife

Impact

Noise

Proper siting of wind turbines is

the best way to address many of

the potential issues that arise.

Wind turbine: horizontal axis

Wind power

Wind turbine: vertical axis

Wind power

Wind turbine: Vortex bladeless generator

Wind power

Vortex bladeless wind generator

Wind turbine: kite generator

Wind power

Source: Global Wind Energy Council, Global Wind Energy Outlook 2014

Wind Systems: Strengths & Weaknesses

Wind power

REEEP / UNIDO; 2006

Strengths Weaknesses

Technology is relatively simple and robust

with lifetimes of over 15 years without major

new investment

Site-specific technology (requires a

suitable site)

Automatic operation with low maintenance

requirements

Variable power produced therefore

storage/back-up required.

No fuel required (no additional costs for fuel

nor delivery logistics)

High capital / initial investment costs can

impede development (especially in

developing countries)

Environmental impact low compared with

conventional energy sources

Potential market needs to be large enough

to support expertise/equipment required

for implementation

Mature, well developed, technology in

developed countries

Cranage and transport access problems

for installation of larger systems in remote

areas

The Technology can be adapted for

complete or part manufacture (e.g. the

tower) in developing countries

Installed capacity 2007 – 2015 per continent

Wind power

Projected Global Capacity

Wind power

Source: Global Wind Energy Council, Global Wind Energy Outlook 2014

Bioenergy

• What is bioenergy?

• Which are the source of Biomass?

• Technologies

• Carbon neutral

• Applications

• Strength and weaknesses

• Market and global overview

What is bioenergy?

Bio-energy

• Biomass energy is

the use of living and

recently dead

biological material as

an energy source

• Ultimately dependent

on the capture of

solar energy and

conversion to a

chemical

(carbohydrate) fuel

• Theoretically it is a

carbon neutral and

renewable source of

energy

REEEP / UNIDO; 2006

Technologies

Bio-energy

REEEP / UNIDO; 2006

There are two main ways to use the bioenergy:

• Biofuels (biodiesel, bioethanol)

• Biopower: use the biomass to generate electricity, the main types

of biopower systems are:

Direct-fired (burns biomass directly)

Cofiring (burns biomass as supplementary energy source)

Gassification (convert biomass into gas (H2, CO, CH4) with an

environment characterized by high temperature and low

oxygen level)

Anaerobic digestion (bacteria decompose organic matter in

the absence of oxygen, producing Methane)

Pyrolysis (produce liquid fuels when the biomass is heated in

absence of oxygen)

Carbon neutral

Bio-energy

REEEP / UNIDO; 2006

Bioenergy applications

Bio-energy

REEEP / UNIDO; 2006

Fuel State Application

Biogas • Supplementing mains supply (grid-connected)

Biogas • Cooking and lighting (household-scale digesters)

• Motive power for small industry and electric needs (with gas

engine)

Liquid biofuel • Transport fuel and mechanical power, particularly for

agriculture

• Heating and electricity generation

• Some rural cooking fuel

Solid biomass • Cooking and lighting (direct combustion)

• Motive power for small industry and electric needs (with

electric motor)

Strengths & Weaknesses

Bio-energy

REEEP / UNIDO; 2006

Strengths Weaknesses

Conversion technologies available in a wide

range of power levels at different levels of

technological complexity

Production can create land use competition and the

usual problems associated with intensive

agriculture (Nutrient pollution, soil depletion, soil

erosion, other water pollution problems).

Fuel production and conversion technology

indigenous in developing countries

Often large areas of land are required (usually low

energy density/yield). In some cases (e.g. corn-

derived bioethanol) may yield no net energy.

Production can produce more jobs that other

renewable energy systems of a comparable size

Production can have high fertiliser and water

requirements

Conversion can be to gaseous, liquid or solid fuel May require complex management system to

ensure constant supply of resource, which is often

bulky adding complexity to handling, transport and

storage

Environmental impact low (overall no increase in

carbon dioxide) compared with conventional

energy sources

Resource production may be variable depending

on local climatic/weather effects, i.e. drought.

Emits less SO2 and NOx than fossil fuels Likely to be uneven resource production throughout

the year

Energy consumed

Bio-energy

A. Brown "The State and Future of Bioenergy", Tokyo

International forum, 17 November 2011

Electric production trends

Bio-energy

A. Brown "The State and

Future of Bioenergy",

Tokyo International forum,

17 November 2011

Biofuels trends

Bio-energy

A. Brown "The State and Future of Bioenergy", Tokyo

International forum, 17 November 2011

Hydro power

• Overview

• Characteristics

• Hydropower: strength and

weaknesses

• Key trends and players in the

hydroelectric market

Overview

Hydro power

REEEP / UNIDO; 2006

Hydropower is divided in four main classes:

• Large hydropower schemes hundreds of MWs

• Small hydropower (SHP) < 10 MW

• Micro < 500 kW

• and Pico hydro < 50W

Characteristics:

• Reliable

• Cost effective

• Lifetime > 30 years

• flexible operations: fast start-up and shut-down

• Most mature of renewable energies

• Largest global contributor amongst all renewable energies

• Largely utilizes established technology from other sectors

• Can be “switched on-off” at almost immediately

• Arguably the Cheapest where available

Technology

Hydro power

Hydropower is divided in two main types:

Impoundment Diversion (run-of-river)

Strengths & Weaknesses

Hydro power

REEEP / UNIDO; 2006

Strengths Weaknesses

Technology is relatively simple and robust with lifetimes of over 30 years without major new investment

Very site-specific technology (requires a suitable site relatively close to the location where the power is needed)

Overall costs can, in many case, undercut all other alternatives

On small streams the maximum power is limited and cannot expand if the need grows

Automatic operation with low maintenance requirements

Droughts and changes in local water and land use can affect power output

No fuel required (no additional costs for fuel nor delivery logistics)

Although power output is generally more predictable it may fall to very low levels or even zero during the dry season

Environmental impact low compared with conventional energy sources

High capital/initial investment costs

Power is available at a fairly constant rate and at all times, subject to water resource availability

Engineering skills required may be unavailable/expensive to obtain locally

The technology can be adapted for manufacture/use in developing countries

Power capacity per country

Hydro power

International Hydropower

Association, "Briefing

2016 key trends in

hydropower", 2016

Capacity added

Hydro power

International Hydropower

Association, "Briefing

2016 key trends in

hydropower", 2016

Pumped storage

Hydro power

International Hydropower

Association, "Briefing

2016 key trends in

hydropower", 2016

Geothermal power

• How it works?

• Main technologies

• Market trends and players

How it works?

Geothermal

• Geothermal direct use

Use hot springs as heat source

• Geothermal power plants

Use earth’s heat to power steam

turbines

• Geothermal heat pumps

Use electricity to exchange heat with

the ground

• Energy available as heat from the earth usually hot water or steam

• High temperature resources (150°C+) are used for electricity generation

• Low temperature resources (50-150°C) for direct heating: district heating,

industrial processing

• No problems of intermittency

REEEP / UNIDO; 2006

Characteristics

Electricity trends

Geothermal

R. Bertani, "Geothermal Power Generation in

the World 2010-2014 Update Report", 2015

How it works?

Geothermal

Electrical Energy System

• How it works?

• Advantage and disadvantages

Electrical Energy Storage Classification

Electrical energy storage

X. Luo et al. Applied Enegy 137 (2015) 511-536

Power vs Energy

Electrical energy storage

X. Luo et al. Applied Enegy 137 (2015) 511-536

Efficiency

Electrical energy storage

X. Luo et al. Applied Enegy 137 (2015) 511-536

Capital vs Maintenance costs

Electrical energy storage

X. Luo et al. Applied Enegy 137 (2015) 511-536

Efficiency

The best way to improve our efficiency is to

reduce our consumption, this often imply that

we need to change and modify our behaviors

Co-generation

• What is cogeneration…

• …and its advantages

What is Cogeneration & its Advantages?

Co-generation

Burns energy once and uses it twice!

• Co-generation: Simultaneous production & use of electricity & heat

Combined Heat and Power (CHP)

• Tri-generation: Simultaneous production & use of electricity & heat &

cooling

Combined Cooling, Heat and Power (CCHP)

What is Cogeneration & its Advantages?

Co-generation

http://www.renewableenergymexico.com

What is Cogeneration & its Advantages?

Co-generation

• Save a lot of wasted energy.

• Decentralize the electricity generation

• Promoting liberalization in energy market.

• Increased efficiency of energy conversion and use

• Lower emissions, especially CO2

• Cost savings

Contributing to prevention of global warming…

• A cogeneration system utilizes exhaust heat which is dumped in generating electricity, and

so makes the most of the limited resources.

• Because it reduces the amount of exhausting greenhouse gas such as CO2 (Carbon

Dioxide) and NOx(Nitrogen Oxides), it can contribute a lot to prevention of global warming.

Applications

Co-generation

Everywhere you need: electricity and heat/cooling

District heating

• Context

• Globally overview

• DHC network rapid integration of lower carbon

new technologies

Context: District Heating and Cooling

District heating

• Heating as the largest single energy end-use

in Europe!

• The majority of energy use come from cities!

• A very large share of energy is wasted!

-> to improve efficiency of energy use

and integrate renewables on a large

scale, it is absolutely necessary to

support efficient and flexible heating and

cooling systems on a local level

throughout Europe

Context: District Heating and Cooling

District heating

• Maximise the efficiency of the thermal electricity

generation process by providing a means to use the

waste heat

• Share heating - and cooling - loads

• Achieve fuel flexibility - opportunities for CHP,

renewables and emergent technologies.

-> to improve efficiency of energy use

and integrate renewables on a large

scale, it is absolutely necessary to

support efficient and flexible heating and

cooling systems on a local level

throughout Europe

Context: District Heating and Cooling

District heating

DHC Network Rapid Integration of Lower Carbon New technologies

• Pipes are ‘technology blind’: any locally available source of heat can be

used

• All buildings on a network receive heat from any new item of plant

installed at central energy center .

DHC - A technology that can

handle peaks

• Heat: aggregate loads have

smoother peaks

• Electricity: heat driven

chillers reduce peak power

demand

International Energy Agency, 2012

Smart grid

• Context

• Globally overview

• DHC network rapid integration of

lower carbon new technologies

Traditional power grid

Smart grid

Generation => Transmission =>

Distribution

• It require big, reliable power

plants and therefore a

limited alternative power

generation sources

• High transmission losses

(~20%)

• Security threats from

energy suppliers or cyber

attack

http://oncor.com/images/content/grid.jpg

What is a smart grid

Smart grid

J. Momoh, 2012, Smart Grid: Fundamentals

of Design and Analysis.

What is a smart grid

Smart grid

What is a smart grid

Smart grid

Smart Grid is an application of digital information technology to optimize electrical

power generation, delivery and use.

• Optimize power delivery and generation

Advanced efficient power generation

Low loss delivery power lines

• Self-healing

Real-time awareness and reaction of system problems

• Consumer participation

Consumer can monitor and control “smart appliances” to manage energy use and

reduce energy cost

• Resist attack

Real time monitoring of power grids

Identify and respond to man-made or natural disruptions

Isolate affected areas and redirect power flows around damaged facilities

• High quality power

Reduce high losses due to outages and power quality issues

• Accommodate generation options

J. Momoh, 2012, Smart Grid: Fundamentals of Design and Analysis.

Key technologies

Smart grid

J. Momoh, 2012, Smart Grid: Fundamentals of Design and Analysis.

• Integrated communications

Fast and reliable communications for the grid

Allowing the grid for real-time control, information and data exchange to optimize

system reliability, asset utilization and security

Can be wireless, powerline or fiber-optics

For wireless (Zigbee, WiMAX, WiFi)

• Broadband over Powerlines

Provide for two-way communications

• Monitors and smart relays at substations

• Monitors at transformers, circuit breakers and reclosers

• Bi-directional meters with two-way communication

Building a smart grid

Smart grid

J. Momoh, 2012, Smart Grid: Fundamentals of Design and Analysis.

Overlay with an “Intelligent” Infrastructure

• Pervasive sensing and measurement devices

• Pervasive control devices

• Advanced data communications

• Computing and information management

Smart

Power

Plants

Transmission

Networks

Substations Distribution

Networks

Consumers

Building multifunctional façade

• Green roofs/walls

• Combined heat and power or CHP

• History of Cogeneration

• Traditional Fuel vs Cogeneration

• Cogeneration: How it will help…

Green roofs/walls

Multifunctional façade

Intensive

• Depth of 1ft. or more

• Involve high maintenance plants such as trees

and shrubs

• Irrigation system often necessary

• High maintenance

• Considerable weight load

• Less common

• Commonly accessible by public

Extensive

• Shallow depth (typically 2-4 in.)

• Low growing, often broad leaved plants

• Plants with ability to withstand harsh weather

conditions

• Extremely low maintenance

• Minimal weight load

Eco Design: A Manual for Eco Design, 2006

Green roofs/walls: advantages

Multifunctional façade

• Stormwater Retention: Green roofs can retain up to

75 percent of one-inch rainfall and help alleviate the

problem;

• Reduction of urban heat island effect: Vegetation

can help provide shade and keep the temperature of

the building surface at low temperature;

• Improved air quality: Green roofs absorb and filter

airborne particles moving across their surfaces.

• Energy conservation: Green roofs impact the heat

gain and loss of a building;

• Increased roof life span: They shield the membrane

from damaging ultraviolet rays maintaining a

consistent membrane temperature and limit freeze-

thaw cycling.

Integrated multifunctional façade

Multifunctional façade

• Combine photovoltaics and solar thermal

systems to supply energy to the building;

• Use new materials to protect and enhance the

performance of the building

• Use new technologies to support the natural

ventilation of the building improving the comfort

and reducing the costs

• Adaptive façade systems building materials for

improving envelope thermal-energy features.

EU FP7

CommONEnergy

EU FP7

Inspire

References

Solar Energy:

• Rugescu D. Radu Solar Energy. ITECH. ISBN 978-953-307-052-0 Hantula Richard (2010). Solar Power (Energy Today).

2010 by Infobase Publishing

• Edenhofer Ottmar et al., (2012). Renewable Energy Sources and Climate Change Mitigation: Special Report of the

intergovernmental panel on climate change.

• Droege Peter (2008). Urban Energy Transition, From Fossil Fuels to Renewable Power. World Council for Renewable

Energy. Elsevier.

• Lund Henrik (2014). Renewable Energy Systems: smart energy Approach to the choice and modelling of 100% Renewable

Solutions. Elsevier.

• Ferry Robert (2012). A field guide to renewable energy technologies. Land Art Generator Initiative.

• Keirstead James, Shah Nilay (2013). Urban Energy Systems: An Integrated Approach. Routledge.

• Droege Peter (2011). Urban Energy Transition: From Fossil Fuels to Renewable Power. Elsevier.

• GEA (2012). Global Energy Assessment: Toward a Sustainable Future. Cambridge University Press.

• REEEP / UNIDO; 2006. Training Manual on Sustainable Energy.

District Heating and Cooling;

• Rezaie Behnaz , Rosen A. Marc , (2011). District heating and cooling: Review of technology and potential enhancements.

Journal of Applied Energy.

• IEA (1999) District-Heating-and-Cooling-Connection-Handbook.

• Andrews David (2012). Background Report on EU-27 district heating and cooling potentials, barriers, best practice and

measures of promotion. European Commission.

• E.ON Energy Research Center. Preliminary Study on New Technologies for District Heating Systems Applying Co-

Generation Units Azadeh Badakhshani, Alexander Hoh, Gesine Arends Dirk Müller Volume 3, Issue 1.

• United National Environmental Programme. DISTRICT ENERGY IN CITIES: Unlocking the Potential of Energy Efficiency and

Renewable Energy. www.unep.org/energy/des

References

Cogeneration

• IEA (2014). Linking Heat and Electricity Systems Co-generation and District Heating and Cooling Solutions for a Clean

Energy Future. www.iea.org.

• IEA/OECD (2009). Cogeneration and District Energy. Sustainable energy technologies for today and

tomorrow….Organization for Economic Co-operation and Development.

Smart City- ICT

• Batty Michael (2013). The New Science of Cities. The MIT Press., Cambridge Massachusetts

• Townsend M. Anthony (2014). Smart Cities: Big Data, Civic Hackers, and the Quest for a New Utopia. W.W

• Geertman Stan, Ferreira Joseph, Jr., Goodspeed Robert, Stillwell John (2014). Planning Support Systems and Smart Cities.

Springer.

• Deakin Mark (2013). Smart Cities: Governing, Modelling and Analyzing the Transition. Routledge, ISBN-13: 978-0415658195.

• Sanseverino R. Eleonora (2014). Smart Rules for Smart Cities: Managing Efficient Cities in Euro-Mediterranean Countries.

Springer.

• Hilty M. Lorenz, Aebischer Bernard (2015). ICT Innovations for Sustainability. Springer.

• Hambleton, Robin (2015). Leading the inclusive city: Place-based innovation for a bounded planet. Policy Press.

• Dameri P. Renata, Rosenthal-Sabroux Camille (2014). Smart City: How to Create Public and Economic Value with High

Technology in Urban Space

• Yalciner O. Ercoskun (2012). Green and Ecological Technologies for Urban Planning: Creating Smart Cities. IGI Global

• Vinod T. M. Kumar (2015). E-Governance for Smart Cities. Springers

References

Smart Grid

• Smart Grids For Dummles® Published by John Wiley & Sons, Ltd

• Gellings W. Clark (2009). The Smart Grid_ Enabling Energy Efficiency and Demand Response. The Fairmont Press, Inc.

• Fox-Penner Peter (2009). Smart Power_ Climate Change, the Smart Grid, and the Future of Electric Utilities. Island Press.

• Flick Tony, Morehouse Justin (2011). Securing the Smart Grid_ Next Generation Power Grid Security. Elsevier

Urban Agriculture and Energy Implications

• NYERDA et al (2013) Sustainable-Urban-Agriculture: Confirming Viable Scenarios for Production. NYSERDA Contract

15592.

Hydrogen

• Crabtree George, et al., 2004. The hydrogen economy. Physics Today.

• American Institute of Physics S-0031-9228-0412-010-3.

ftp://210.212.82.99/Journal's%20CD/digit/DigitJun2010mw%20(F)/Documents/Technologies/Hydrogen_Economy/38648-

hydrogen_economy.pdf