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A R e n e w a b l e E n e r g y G u i d e f o r D e v o n
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ContentsChapter Page
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 1 - Introduction . . . . . . . . . . . . . . . . . . . . . . . 5
Chapter 2 - Energy from Biomass . . . . . . . . . . . . . . . . 13
2.1 Wood Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2 Energy Crops . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.3 Biomass Combined Heat and Power (CHP) . . . 35
2.4 Anaerobic Digestion (AD) . . . . . . . . . . . . . . . . 39
Chapter 3 - Wind Power . . . . . . . . . . . . . . . . . . . . . . . 47
Chapter 4 - Small-Scale Hydro Power . . . . . . . . . . . . 61
Chapter 5 - Solar Photovoltaics (PV) . . . . . . . . . . . . . 71
Chapter 6 - Community Based Renewable Initiatives 77
Annexes
1. Government grants and support programmes
for renewable energy . . . . . . . . . . . . . . . . . . . . . . 81
2. Developers, contractors and suppliers of
renewable energy equipment and services . . . . . . 83
3. Useful contacts and websites . . . . . . . . . . . . . . . . 88
2 A R E N E W A B L E E N E R G Y G U I D E F O R D E V O N 2 0 0 4
C O N T E N T S
A Renewable Energy Guide for Devon 2004
AuthorsDr Robin Cotton, Stewart Boyle and Jenny Carey-Wood.
Renewable Heat & Power Ltd.
Published by
Devon County Council, Economy & Regeneration Service,
County Hall, Exeter. EX2 4QD
Tel: 01392 383543
Email: [email protected]
Website: www.devon.gov.uk
This document is available on the above website.
February 2004.
Funded by
Devon County Council.
SWRDA.
Countryside Agency.
Acknowledgements
Renewable Heat & Power Ltd would like to thank the followingfor their kind co-operation and assistance with this project:
Phil Davis and colleagues from Hydro-Generation Ltd, for input
to the chapter on Hydro; Greenergy and British Sugar staff for
advice on the biofuels chapter; Andy Russell for input to the
Biomass CHP chapter; the Energy Savings Trust and Solar
Century Ltd for input to the solar PV chapter; DARE for input
on the Community Renewables Initiative; Regen SW and
countless individuals who reviewed earlier drafts of this Guide.
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Renewable Energy in Devon:
A Complete Guide to Renewable
Energy for Land-based Industries1
ForewordThe UK Government has recently committed itself to a
60% reduction in carbon dioxide emissions by 2050.
This will require an enormous change in society across
all sectors - an energy revolution. It will also be a huge
opportunity for new, cleaner industries to emerge in the
UK.
The County of Devon aims to be at the forefront of this
enormous change, utilising our significant naturalresources in a sensitive and economic way to the benefit
of the environment, our hard-pressed agricultural and
forestry industries, and local people. We see the
opportunity to generate good local jobs on the back of
this energy revolution.
Why aim a guide dealing with the production and
supply of energy at land-based industries? Because it is
the land that provides us with the resources needed to
produce renewable energy. Wind, water and wood
supplied mankind with energy long before thebeginning of the twentieth century and before the
discovery of fossil fuels. Today these sources of
renewable energy are once more assuming importance
for a number of compelling reasons.
The main reason is climate change. The burning of fossil
fuels to create energy is one of the main causes of
climate change. Renewable energy, which does not emit
greenhouse gases into the atmosphere, is therefore seen
as a key element in combating climate change.
Secondly, international and national targets for the
reduction of CO2 emissions and development of
renewable energy have increased the importance of
renewables on the political agenda. Thirdly, renewable
energy, which is not imported from politically volatile
countries, provides a secure energy supply not affected
by price fluctuations.
A fourth reason is the benefits that local, clean energy
can bring to a local economy, especially in rural areas.
Renewable energy has the potential to play a part inrural regeneration and the aim of this Guide is to
contribute towards rural recovery by providing a one-
stop-shop of information on what is involved.
It contains essential and comprehensive information
which is needed to recognise opportunities, implement
projects and develop business and market potential.
The various technologies are described and costs
outlined wherever possible. Case studies demonstrate
working examples of the technologies and the
appendices include information on suppliers and
funding.
We trust that this Guide will offer support and
encouragement to those land-owners, foresters,
communities and companies interested in renewable
energy and, in doing so, contribute towards the
development of a new vibrant rural industry.
Councillor Derrick Spear
Executive Member for Economic Regeneration
Devon County Council
3A R E N E W A B L E E N E R G Y G U I D E F O R D E V O N 2 0 0 4
F O R E W O R D
1 A Complete Guide to Renewable Energy for Land-based
Industries has been produced for Devon County Council by
Renewable Heat and Power Limited with funding from the
South West of England Regional Development and Countryside
Agencies.
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Highlights Climate change is forcing us to make changes in the
way we run our societies in a long-term shift towards
a fossil free energy system.
The UK Government has committed to a 60% cut in
carbon dioxide emissions by 2050.
Shifting to renewable energy is now backed by the
UK Government, the European Union and the Earth
Summit in Johannesburg, August 2002.
Renewable energy comes from natural sources suchas wind, water, sunshine or plants and trees.
They are continually renewed by energy from the
Sun and hence will never run out, unlike fossil fuels
and nuclear power.
The global market for renewable energy is now
worth 50 billion a year and is growing faster than
conventional fossil fuels.
The UK renewable energy market is currently
growing at a rapid rate in line with a Government
target to get 10% of our electricity from renewablesby 2010 and to meet tough carbon dioxide
reductions.
As well as environmental benefits, renewable energy
can offer alternatives to fossil fuels, the opportunity
for local manufacturing, development and
implementation, as well as providing much-needed
income for the hard-pressed UK farming and
forestry sectors.
The opportunities for capturing and benefiting from
renewable energy in Devon and throughout the
South West region are significant. Devon has
excellent resources for wind and wood energy, with
strong additional resources from small-scale hydro
(water) power and organic wastes.
What is Renewable Energy?Renewable energy will never run out as long as the Sun
shines, unlike the so-called conventional sources of
energy which refer to fossil fuels (oil, coal and gas) and
nuclear energy.
The use of the term conventional when referring to
fossil fuels and nuclear power is perhaps surprising,
since before the industrial revolution renewable energy
was the only form of power available apart from labour
from human and animals.
Therefore, renewable energy is nothing new. It was
overtaken for a century or more by fossil fuels, but
recently a number of important factors have combined
to ensure that renewable energy is again likely to make
a very substantial contribution to our future energy
supply.
The Drivers of Renewable Energy
1. Climate Change: The need to reduce carbon
dioxide emissions
International concern over the environmental impacts
of the worlds uncontrolled use of coal, oil and gas has
grown in the second half of the twentieth century.
During the mid-1980s, awareness began to increase of
yet another problem caused by fossil fuels - climate
change, also known as global warming or the
greenhouse effect. The gases that cause warming
(known as greenhouse gases) given off when fossil fuels
are burnt are increasing in the atmosphere. Manyscientists say this is leading to rises in global
temperature and sea levels.
The most important greenhouse gas is carbon dioxide
(CO2). Concentrations of carbon dioxide in the
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Chapter 1
Introduction
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atmosphere today are already 30 per cent higher than
the levels which existed before the Industrial
Revolution.
Global Climate Change is one of the most important and
largest threat facing our planet. It is already causingchanges in weather patterns which are predicted to get
substantially worse over the coming decades with
potentially catastrophic consequences. A growing
number of reports on the impact of climate change on
the insurance industry suggest that weather related
damage costs could climb massively, leading to many
areas being excluded from insurance protection. Homes
in flood-plains are already facing both high premiums
and potential red-lining by insurance companies.
2. UK and European Legislation
In 1997 more than 160 nations met in Kyoto, Japan, to
negotiate binding limitations on greenhouse gases for
the developed nations. The outcome of the meeting was
the Kyoto Protocol, in which the developed nations
agreed to limit their greenhouse gas emissions, relative
to the levels emitted in 1990. Over and above the Kyoto
Protocol, the UK Government also has a commitment to
reduce CO2 emissions by 20% of 1990 levels by 2010. In
February 2003 it committed the UK to a 60% cut in CO2
emissions by 2050. As renewable energy contributes
little or no net carbon dioxide, it can play a central role
in meeting these targets.
The UK now has a target of getting 10% of its electricity
from renewable energy by 2010. Currently the UK
obtains around 3% of its electricity supply from
renewable energy, much from older hydro schemes in
Scotland. For the Government, a strategic approach is
important for the development of renewable energy at
a regional level. In 1999 it commissioned reports1 on
the potential for renewable energy in each region.These reports also set regional targets for renewable
energy generation. Devon has been identified as having
significant potential and the target set for the County is
15% generation from renewable sources by 2010.
Following on from the regional assessments and targets,
the Government Office for the South West (GOSW) and
the Regional Development Agency (RDA) published a
Strategic Framework for the Development of Renewable
Energy in the South West in June 2002, with its strategy
published in April 2003. This will spell out themechanisms and support for implementing its targets.
Renewable energy is gaining in political importance in
direct relationship to growing concern about Climate
Change and its impacts. Government has set aside
funding for renewable energy projects and has
introduced mechanisms to encourage its market
development. The first of these support mechanisms
was the Non-Fossil Fuel Obligation (NFFO) which
provided a premium price for up to 15 years for the
electricity generated from renewable sources. This hasbeen discontinued and a new approach - the
Renewables Obligation (RO) - is now underway.
The Renewables Obligation places an obligation on
electricity suppliers to acquire an increasing percentage
of their supplies from renewable sources and cover the
additional costs. Where they are unable to fulfil their
obligation, they may purchase Renewable Obligation
Certificates, or ROCs from other suppliers (these relate
to metered units of renewable electricity), or buy out
their obligation by making a payment to OFGEM, the
industry regulator. It is anticipated that this new
approach will stimulate the development of renewable
electricity generation to replace existing provision. It is
likely that the RO will mean a premium in excess of
3p/kWh for electricity produced from renewable sources
i.e. a supplier of renewable electricity may be able to
obtain 3 pence above the normal wholesale price of
electricity. Indeed, due to the shortage of ROCs at this
stage of the market, the estimated price is likely to be
between 4.5-5p/kWh as far out as 2006.
6 A R E N E W A B L E E N E R G Y G U I D E F O R D E V O N 2 0 0 4
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1 Renewable Energy Assessment and Targets for the South
West, Terence ORourke plc and ETSU - February 2001
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3. Technology Development
Over the past two decades we have seen substantial
technological advances in all renewable energy
technologies. We have seen wind turbines increase in
efficiency by a factor of 2 and achieve a substantial
improvement in reliability to the point where 99%availability is the norm. We have seen automatic wood
heating systems (using wood chips or wood pellet fuel)
increase from a typical 55% efficiency in 1980 to now
over 90% for most systems. We have also seen new
materials being used for small-scale hydropower
turbines to bring down costs and research of
photovoltaics continues to increase the efficiency at
which sunlight can be directly converted to electricity.
4. Local resources, local jobs
Most of the fossil fuels used for heating, electricity and
transport come from either the North Sea, are imported
from, for example the Middle East, or dug from the
ground in the UK, Venezuela or South Africa. Over the
next decade it is likely that the proportion of fossil fuels
that is imported will increase dramatically as reserves of
oil and gas in the North Sea are spent and UK coal
mines continue to decline in competition with imported
coal. Without a greater role for renewable energy the UK
could become over-dependent on imported natural gas.
This has a number of important consequences.
Firstly, fossil fuels and particularly oil are subject to
price fluctuations triggered by world events.
Secondly, to be dependent on suppliers from abroad in
politically unstable regions is dangerous. While green
power, and renewable heating via wood for example,
may be more expensive today than mains natural gas,
(though some biomass heating options can match gas
on price), the prices are much more stable. A growing
proportion of renewable energy can hence help bring
price stability in the market by giving customers optionswhich wont be affected by wars in the Middle East.
Thirdly the environmental cost of bringing fuels from
across the world is substantial, but rarely questioned.
Last, but not least, when imported fossil fuels are used,
for example in domestic oil heating, most of the
economic wealth goes immediately out of the local
economy and ends up with Multinationals and overseascompanies.
Renewable energy does not need to be imported, it is
all around us waiting to be captured by technology.
The economic benefits in capturing renewable energy,
installing equipment, providing fuel and maintaining
systems will often be local, which is not the case with
imported fossil fuels. With Devon being badly affected
by the downturn in farming and associated feed and
machinery industries, plus difficult times for the forestry
industry, renewable energy provides an opportunity toinvest locally and bring local benefits.
Renewable Energy in Europe
There is currently a very strong drive within the
European Union to increase the total amount of energy
(heat, electricity and transport) from renewable energy
sources from its current level of 6% to 12% within the
next 10 years. However, within the average level of 6%
there is a wide disparity between the different memberstates. Figure 1.1 shows the percentage of total energy
usage that comes from renewable energy sources by
country in order.
At the top end of the list are Sweden and Austria who
both produce over a third and a quarter respectively of
all the energy they consume from sustainable and
indigenous sources of energy. The main renewable
contributions to their energy supply come from hydro-
electric power and from wood heating. The Austrian
Government have recently commissioned a strategydocument which looks at achieving 100% of the
countrys energy needs (including heat, electricity and
transport) from renewable sources by 2075. This is open
for debate and discussion.
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At the moment the UK is firmly at the bottom left of the
league table (fig 1.1) with about 1% of our energy
(corresponding to about 3% of electricity) coming from
renewable sources. The majority of this comes from
large-scale hydropower built in the last 40-70 years and
from traditional low efficiency log burning in open firesor stoves.
Yet the UK has a huge potential resource to exploit a
range of renewable technologies, the ones most
relevant to land-based industries are covered in this
guide. We concentrate on the main options of wind
power, small-scale hydro, biomass energy and liquid
biofuels. We will not cover offshore wind power and
cover only briefly solar photovoltaics (PV).
The Potential Role of
Renewable Energy
Renewable energy has the potential to supply the whole
of the UKs energy needs. It could do this with very low
or zero net carbon dioxide emissions and this would
enable the UK to be self reliant in energy, with energy
sources being locally derived and locally owned.
While this would cost more than current sources, there
is a big potential to reduce costs over time. If renewable
energy was linked to reducing energy demand through
a serious energy efficiency effort, the overall energy
costs to the consumer might in fact be similar or even
lower than today. This was a conclusion reached by theGovernments Performance and Innovation Unit (PIU) in
its report on Energy Policy in early 2002.
Renewable energy technologies are now beginning to
compete economically with fossil fuels and there are a
number of grant programmes available to help
establish and expand the emerging renewable energy
industries. These include:
subsidy support for renewable based electricity
grant support for farmers establishing energy crops capital grant support for a range of technologies
enhanced capital write-offs for many renewable
technologies
exemption from the Climate Change Levy
grant support for community energy projects
A list of programmes is given in Annex 1.
8 A R E N E W A B L E E N E R G Y G U I D E F O R D E V O N 2 0 0 4
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Figure 1.1The percentage of total energy
usage (heat, electricity and
transport) from each European
Country derived from renewable
sources
0
5
10
15
20
25
30
35
Sweden
Finland
Austria
Portugal
Denmark
Italy
France
Spain
Greece
Germany
Netherlands
Ireland
Luxembourg
Belgium
UnitedKingdom
Percentage(%)
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Renewable energy also has the potential to revitalise
the rural economy. Local energy supply requires local
skills, creates local jobs and needs local resources. The
development of a vibrant local rural renewable energy
industry would bring many economic and social
benefits as well as environmental gains.
Environmental Benefits
Fossil fuels are made up of carbon that was taken out of
the atmosphere millions of years ago by a slow, steady
process that still goes on today. Burning fossil fuels puts
large amounts of additional carbon dioxide into todays
atmosphere, which is widely accepted to be changing
our climate; we are already feeling the effects of more
flooding, drought and other extreme and unseasonable
weather conditions.
Burning wood and other biomass fuels does not add
this extra CO2 to our atmosphere; they are CO2-neutral.
By burning wood fuel or using wind or water instead of
fossil fuels, we can avoid adding extra carbon dioxide to
our atmosphere and reduce our impact on the Global
Climate.
As we move into the new millennium, the search for
cleaner, more sustainable, renewable sources of energy
as well as ways to revitalise rural economies seems
likely to bring people back to using wood, wind and
water as fuels. The local ownership, management and
supply of fuel for renewable energy systems additionally
reduces the transport and pollution costs of traditional
fossil fuels.
Economic Benefits
The small scale of much renewable energy activity can
provide direct economic benefits at a very local level.
The majority of systems using wood, other biomass or
hydro power are owned and managed at local levelrather than by national or multi-national companies. As
a result, the profit and job creation to manage and
maintain renewable energy systems benefits local
people, often in areas looking for economic
diversification and direct job creation such as the more
isolated rural areas. In addition, money spent can stay
in a local community with the multiplier effect of
money being re-spent locally providing added benefit.
Financial BenefitsWhile the capital costs are relatively high, renewable
energy systems tend to have very low running costs,
good reliability, a long lifetime for the equipment and
low or zero annual fuel costs. Since it uses renewable
sources of fuel, once a system is installed it is likely to
continue operating indefinitely because the fuel source
will always be there. Where fuel costs are applicable,
such as with wood where the fuel needs to be bought
in, wood fuel remains very competitively priced
compared to fossil fuels.
With Global Climate Change high on the political and
environmental agenda and the need to reduce carbon
dioxide emissions, a premium price is likely to continue
to be paid for electricity from renewable sources. This
can provide a useful income for those generating
electricity surplus to their requirements.
The Potential Resource in
the South-WestThe South West of England has enormous potential in
terms of renewable energy generation due to the
landscape, coastline and land-use patterns. A regional
study identified over 100 potential renewable schemes
to generate between 200 and 550 MW of electrical
power. This could provide between 11% and 15% of the
regions electricity requirements if the right conditions
were provided to support renewable energy
developments. Heat production and liquid transport
fuels would be in addition to this.
Issues related to planning, regulations, politics,
institutional barriers and economics are however
currently hindering these developments.
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At the local level, there is considerable potential for
renewable energy production whilst taking into account
the protected landscapes and population distribution
within Devon. This guide aims to demonstrate how this
can be achieved at both the private level (producing
heat/power to meet own requirements) and at thecommercial level (selling surplus electricity). Although
domestic scale schemes will not count towards the
regional target, they will make a contribution to
reducing global warming, especially if combined with
attempts to reduce overall energy consumption.
The Current Situation in Devon
Devon currently receives about 1.8% of its energy needs
from renewables. Most of this has come from methane
gas from landfill sites (not really considered a renewable
source) and small hydro schemes. In 2002 the
Holsworthy Biogas Plant began energy production using
animal slurry as fuel. An agricultural co-operative, South
West Wood Fuels Limited, supplies wood fuel to a
growing number of wood heating installations in the
South West. Interest in renewables is growing and the
smattering of small-scale individual and community
projects is slowly increasing.
A community-led Devon Association for RenewableEnergy (DARE) was formed in 2001, and has teamed up
with Cornwall under the Countryside Agencys
Community Renewables Initiative to provide
information, support and encouragement for
community schemes. Regen SW, the Regional
Renewable Energy Agency of the South West was set up
in Exeter in 2003. Devon also has a number of
companies dealing with renewable energy within the
County.
This is an exciting time for businesses, communities and
individuals across the county to get involved in the
renewable revolution that is changing the way we use
energy in the UK. There are significant opportunities to
provide energy services in new ways which dont
damage the environment. Many of these providebusiness opportunities for landowners, farmers, and
other entrepreneurs and communities, to use local
resources. This Guide provides a step by step guide to
using the range of renewable resources and
technologies, as well as insights to successful projects,
the economics of renewables, and a wide range of
contacts and information.
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What it Means
Terminology and Glossary
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Units of PowerKilowatt (kW) = 1000Watts
Megawatt (MW) = 1000kW
When e is added (e.g. kWe) this means electrical power.
When th is added (e.g. kWth) this means thermal power (heat).
Glossary
AD Anaerobic Digestion
CHP Combined Heat and Power
CO2 Carbon Dioxide - a gas given off when fossil and plant
material is burnt and absorbed by plants when they grow.
CRI Countryside Agency Community Renewables Initiative
DARE Devon Association of Renewable Energy
DEFRA Department of the Environment, Food and Rural Affairs
DTI Department of Trade and Industry
EA Environment Agency
EST Energy Savings Trust
EU European Union
GDP Gross Domestic Product
GOSW Government Office of the South West
LA Local Authority
NFFO Non Fossil Fuel Obligation
RE Renewable Energy
REGEN SW South West Renewable Energy Agency
R&D Research and DevelopmentRO Renewables Obligation
SRC Short Rotation Coppicing
SWRDA South West of England Regional Development Agency
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HighlightsGeneral
Biomass energy is a term used to describe heat and
power produced from wood, forest and agricultural
residues and wastes, and a wide range of organic
wastes such as animal slurry and kitchen waste.
Modern technology converts biomass to heat, power
and liquid fuels efficiently and conveniently.
Modern automatic wood heating is very common
across Europe, particularly in Austria, Denmark,Sweden and Finland.
Wood and other biomass is a significant resource
which, as long as re-growth or replanting takes
place, emits no net carbon into the atmosphere as
growing biomass absorbs carbon.
An integrated wood fuel and energy production
system provides a sustainable and clean approach
that has the added advantage of stimulating local
woodland management and local economic benefits
including jobs.
The Biomass Resource
The global biomass resource is massive. It provides
11% of global energy use and the potential is
estimated as 65-100% of current global energy use.
In the UK wood is the biggest renewable energy
source at present, but much of this is used in
relatively inefficient open fires and stoves. The
potential in the UK for all biomass resources is more
than one-third of total energy demand.
Biomass Technology
Biomass in this Guide is sub-divided into wood fuel,
woodland residues for heat and power generation,
crops used for liquid fuels in the transport sector,
energy crops for heat and power, and wastes
digested to produce power and heat (see Chapter
2.1, 2.2, 2.3 and 2.4 respectively).
At present, wood fuel in the UK can be cheaper than
most fossil fuels, and modern automatic wood
heating technology is reliable and readily available.
Power generation from biomass has been provedeconomical using straw and chicken litter as well as
municipal waste. Some positive experience with
biomass Combined Heat and Power (CHP) has also
been gained, though most systems are currently
uneconomic without a large subsidy.
Biomass power systems can gain subsidies through
Renewables Obligation Certificates (ROC) and Climate
Change Levy (CCL) exemption.
Advanced biomass power systems which gasify
special energy crops and pyrolysis, which turnsorganic materials into oil, have not proved
economical or fully commercial but may do so in
the near future.
Liquid biofuels, in the form of bio-diesel for
example, using rapeseed oil, has not yet been
produced commercially in the UK and is mainly
imported from mainland Europe. Diesel with a 5%
bio component is available for local authorities and
other vehicle fleets in the UK, with guaranteed
carbon reductions.
Animal slurry and food waste has been digested to
produce heat and power, though only a few systems
exist in the UK.
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Chapter 2
Energy from Biomass
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An IntroductionWood was the first fuel mankind learned to use.
The first fires of primitive peoples burned wood for
warmth and cooking. It is also a natural resource,
which can be regenerated - unlike fossil fuels, which will
eventually run out.
Up until 200 years ago, wood was the main fuel for
heating in the UK, and influenced much of woodland
management to meet this demand. However, with the
discovery of coal and then oil and gas, the use of woodas a serious heating fuel in the UK, as opposed to log
burning for enjoyment, virtually ceased. However, with
the development of high-efficiency, automatic heating
systems over the last two decades in mainland Europe a
major industry has grown up, with many hundreds of
thousands of systems operational. The UK has been
slow to take up this technology, but over the last few
years it has become established in the UK and is now
being supported by the UK Government.
It is also important to note that traditionally wood wasused in open fires or primitive wood stoves, which
burned very inefficiently. This not only made it
expensive - with up to 85% of the useful heat going up
the chimney - but also polluting with smoky fires. This
is the image many people have of wood burning -
smoky, open fires which produce a lot of ash and which
sometimes go out when most needed.
However, modern wood heating is clean, efficient,
convenient and can compete on cost with most heating
systems. This has been achieved through controlling
airflow, using thick boiler insulation and re-burning flue
gases. There have been huge advances in wood burning
technologies in recent years, mainly driven by a number
of European countries, especially Scandinavian
countries, Austria and North America. This revolutionhas largely bypassed the UK, with a few notable
exceptions. Now is the time to expand the wood
heating industry in the UK, using the latest technology.
As well as being able to compete on cost and
convenience with most other forms of heating, wood
fuel has a number of important benefits that should not
be forgotten.
The Benefits of Wood EnergyWood is a renewable and sustainable source of
energy. Trees grow every summer using the energy of
the sun to fix carbon from the atmosphere. Every
woodland has a sustainable yield of timber, which can
be harvested indefinitely without depleting the resource
in any way. Wood is carbon neutral and does not
contribute to greenhouse gasses. Burning wood gives off
carbon dioxide just like fossil fuels, but this is balanced
by the carbon absorbed by the growing trees. Un-
harvested wood will give off the same amount ofcarbon dioxide when it eventually decomposes as it
would have done if burnt in a boiler. Burning wood
replaces the burning of fossil fuels.
Wood is a very clean and safe fuel. Wood chips and
pellets present no risk if accidentally released into the
environment, unlike oil which is a serious pollutant and
gas which can explode. There are no harmful by-
products. The flue gas is smoke-free and the ash
content of between 0.5% and 3% by volume (depending
on material), is minimal. Unlike coal ash, wood ash isan excellent fertiliser and can be used in the garden or
returned to the forest. Modern appliances burn very
cleanly with minimal smoke.
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Chapter 2.1
Wood Fuel
Wood is an environmentally friendly renewable fuel which can make a substantial
contribution towards replacing fossil fuels and aiding the rural economy.
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Wood fuel benefits woodland management. It creates
a market for timber and wood residues which would
otherwise have no market or go to landfill. It can
provide financial support to woodland management
activity, and have a positive impact on flora and fauna if
managed appropriately.
Wood fuel benefits the local economy. Wood as a fuel
can now compete on cost with fuel oil, liquid petroleum
gas (LPG) and electrical heating, and in some cases
mains gas. Supplying wood fuel and associated services
to these emerging markets is a major opportunity for
rural businesses. It can create local jobs and income,
and can play a key role in diversifying the rural
economy. For example, labour comprises the biggest
element of the cost of wood pellet production.
Therefore, the main cost in fuel supply goes to localpeople rather than to remote multinational companies.
Wood Fuels
Wood fuel needs to be refined like other fuel sources
such as coal and oil, but in different ways. It requires
drying to reduce moisture content, and reduced to a
size that makes handling easier. Wood fuel can come in
many different forms all of which will have different
combustion properties, behave differently in terms of
handling, and are suited to particular types of boilers.
Wood fuels are divided into three main types:
Log Wood
Densified fuels such as pellets (fig 2.1) and
compressed logs (briquettes)
Wood Chips (fig 2.2)
Wood Fuel Characteristics
The critical elements in describing a particular wood
type are Moisture Content, Particle Size and Bulk
Density of Wood.
If wood fuel is sold by weight the critical parameter is
the moisture content. The energy density of 1 tonne of
well seasoned logs is considerably higher than 1 tonne
of green logs. For seasoned logs you are likely to bebuying about 3/4 tonne of dry wood and 1/4 tonne of
water. With green logs the figures are more likely to be
1/2 tonne of dry wood and 1/2 tonne of water. This has
very important implications for transporting fuel - there
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The Carbon Cycle
Carbon dioxide (CO2) is taken from the
atmosphere and used by trees to grow.
When these trees die and decay or areburned, this CO2 is released back into the
atmosphere. In a mature, unmanaged
forest the amount of carbon being
absorbed by growing trees is the same as
the amount being given off by decaying
dead trees, and by the animals, microbes
etc. that live off the trees as they live and
die. For a sustainably managed
woodland, or energy crops, the process is
similar. On balance, wood is never
removed faster than it is added by new
growth. Therefore the CO2 released when
the wood fuel is burned is never more
than the CO2 being taken up by new
growth. It is therefore termed carbon
neutral.
Figure 2.1Wood pellets made from virgin sawdust.
Figure 2.2
Wood chips from forestry residues.
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The Energy Density of Wood
It is important at this stage to be clear that the energy density
(e.g. the amount of energy per kilogram measured in kWh/kg)
of dry wood (i.e. with zero moisture content) is almostindependent of species of wood.
e.g. 1kg of dry oak (a hard wood) has about the same energy
content as 1kg of dry willow (a soft wood). The volume will be
quite different as oak is considerably denser than willow.
is a considerable cost associated with transporting
quantities of water! There is also a considerable loss ofenergy in evaporating the excess moisture when
burning the fuel, so using high moisture content fuels
will mean lower efficiency and greater cost and has
other negative effects.
The right wood fuel for a particular situation will
depend on a few key properties:
The physical size and shape of the material - logs
must be the right size to fit in the stove or boiler
and wood-chips must pass through the fuel
handling machinery.
The species of tree - hardwoods are generally
denser than softwoods so a hardwood log will give
off more heat than a softwood log of the same size.
However, the heat output per weight (unit mass) is
roughly the same for all woods at the same moisture
content. So the volume of wood (but not the
weight) required for a particular power output will
vary depending on the species.
The moisture content of the wood - damp wood is
heavier and gives off less heat than dry wood.Freshly felled wood may contain over 50% moisture
compared with dry wood such as building timbers
that have a moisture content of 10 to 15%. Wood
chips for heating is usually supplied at 25-30%
moisture or less.
Drying - the importance of low
moisture content
The efficiency of wood fuel is closely linked to the
moisture content of the wood when it is burnt in a
boiler or burner (fig 2.3). Therefore the key question
regarding using wood as a fuel is how is the moisture
content of the raw wood to be reduced? There are
three main approaches to this problem.
Traditionally logs are seasoned by being left out or
undercover for a summer and dry naturally.
Moisture contents of about 25% are typically
achieved, less if the logs are well stacked and
covered.
An alternative approach is simply to burn the green
wood (i.e. freshly cut) directly. In this case the
moisture is reduced in the boiler or fire. However,
this greatly reduces the calorific value of the fuel,
makes good combustion difficult (generally meaning
low combustion efficiency), leads to greater
accumulation of tar deposits in the flue/chimney,
and can mean transporting a high proportion ofwater.
Figure 2.3
Energy Value of
Wood as a Function
of Moisture ContentThe available energy of wood
as function of moisture
content (taking into account
the energy required to remove
water prior to combustion).
CalorificValue(MWh
/tonne)
Moisture Content (%)
00
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
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The third approach is to reduce the moisture
content close to where the wood is produced by
forced drying. This happens in a pelleting or
briquetting plant where the raw material is finely
divided, force-dried and compressed. The end
product is a dense, low moisture content fuel(typically less than 10%), which is convenient to
transport and handle. The downside of this fuel
processing is the cost involved both in terms of
money and energy input. Despite this, pellet fuel is
a fast growing sector in Europe and North America
and wood pellets are now being made in the UK
with pellet production planned in Devon by Spring
2004.
Transport of Wood Fuel
The transport of low bulk density materials is a major
cost, which will affect the cost of fuel delivered into a
fuel store. A 20m3 agricultural trailer will contain about
3.5 - 5 tonnes of wood chip at 25% moisture dependingon the species of wood. Wood chip bought
commercially is likely to cost in the region of 40-45 per
tonne, about half the current price of heating oil (at say
20p/litre) for the same energy. Therefore a single 20m3
load of chip will have a commercial value of about
150-200. To make this economic, the supply of wood
chip should be as local as possible - ideally within a 10-
mile radius. This is also desirable from an
environmental perspective, reducing the amount of
diesel used to deliver the wood fuel.
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Technical Aspects of Wood Fuel
Calculation of Moisture Content (MC)
There are two different ways of specifying the moisture
content of wood; on a wet basis or dry basis. The moisture
content of a single piece of wood will be different using the
two methods and so care must be taken to be clear which
method is being used. Generally speaking the moisture
content of wood should always be calculated and specified on
a Wet Basis.
The moisture content (on a wet basis) of a piece of wood is
given by the mass of water contained in the wood divided by
the total mass of the piece of wood as found.
Example: A sample of wood chip has a mass of 10kg. It is
dried to an oven-dried condition, and then it has a mass of
8kg. What is the moisture content of the wood chip?
The mass of wet wood (10kg) - mass of oven dried wood
(8kg) = mass of water (2kg)
Density and Bulk Density of Wood Fuel
The bulk density of the wood fuel has very important
implications for both storage and transport. This is one of the
major advantages of wood pellets compared to wood chips.
It is important here to make the distinction between density
and bulk density. For example, good quality wood pellets
when put in water sink like a stone i.e. they have a Density
greater than that of water (i.e. >1000kg/m3).
However, when put in a container you will find a volume of
1m3
will have a mass of somewhere between 600 to 700kgdepending on the density and size (diameter and length) i.e.
wood pellets have a Bulk Density of about 600 to 700kg/m3.
Seasoned wood Chips (at 25% moisture content) will have a
bulk density of between 150 to 250kg/m3 depending on
species.
Fuel Storage
Table 2.1 shows a comparison of the storage volumes
between heating oil, wood pellets and wood chips. A typical
oil store for a house would typically be 1,000-1,500 litres,
which would be filled perhaps twice a year. An equivalent
wood pellet store might be twice the volume say 2,000 to3,000 litres and filled perhaps three times per year. A store
for wood chip would need to be considerably larger. This is a
major factor when considering a wood chip-fired heating
system.
Mass of Water (2kg)
Mass of Wet Wood (10kg)
x 100 = 20% (MC)
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stable. It should also be noted that the efficiency of the
appliance will have a dramatic effect on the cost of the
price per unit of energy. For example logs burnt in an
open fire at 10% efficiency will cost eight times more
per unit of useful heat compared to wood chips burnt at
80% efficiency, if the price of the wood was equal.
Wood Fuel Processing and Supply
Wood Chips
It is important to have an understanding of the
practicalities of wood fuel supply, and where
interactions between supply and utilisation occur.
The entire fuel supply chain will ultimately depend
upon the requirements of the market. Production
processes do not necessarily produce fuel of aspecification needed by the end user, either for particle
size or moisture content. As a result, further well
controlled processing at some kind of wood-fuel depot
may be required. Where wood chip is being supplied
this will often mean that the wood is best air dried
before processing as drying chipped material can
present its own difficulties.
Choice of harvesting equipment will depend on terrain
and availability. Farm tractor based equipment will be
appropriate on less steep sites. More specialist forestryequipment will be required on difficult sites with
bumpy terrain.
The main elements of any wood fuel supply chain are
as follows, but not necessarily in this order:
Fell trees; if not already done.
Primary process (e.g. cross cut and branch removal).
Extract to processing point.
Store & dry.
Process to logs or chips. Transport to end user.
These elements need to be tied to the resource and
product specification.
Chipping Wood Residues
Chippers are used to reduce the size of wood residues
for ease of handling and to fit boiler feed systems. There
are 3 main types of chippers:
The disc chipper (see Figure 2.6) consists of a heavy
rotating disc with usually 2, 3 or 4 blades mounted on
the face of the disc. Material to be chipped is fed in,
towards the blades. The rotating knives cut woody
material into chips as they pass an anvil or fixed knife.
Blower paddles on the back of the disc accelerate the
chips up a spout where they are discharged.
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Example of Wood Fuel Processing:
Oak crown-wood to produce a wood
chip fuel - the Production Steps
Primary Process into cordwood using a chainsaw.
Forward to roadside to stack; Easy site - farmforwarder; Difficult site - custom forwarder or cable
crane.
Dry in round to MC25%; Usually - 1 summer;
Large oak - 2 years. Cover in winter to stop re-wetting.
Chip as required; Super or Fine chip - drum chipper
with sieve; Fine or Coarse chip - various chippers.
Chip direct to store or to delivery vehicle or to
big bag, roll on-roll off ro-ro bin or other delivery
package.
Figure 2.5
Wood Chips being stored undercover in a depot.
A tractor mounted disc chipper with a front loader can
be seen in the background.
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Wood Pellets
Producing Wood Pellets
Wood pellets are usually made from compressed
sawdust and wood shavings. However, they can be
made from most biomass material (e.g. straw, forestry
residues, specially grown energy crops etc.) and hence
have the potential to be sourced from locally unused
material, which can then give considerable benefit to
the local economy.
Pellets are typically 6mm - 10mm in diameter
(depending on the size of the heating system) and
resemble animal feed. In fact the manufacturing
process is similar in many ways. A pellet production
facility will traditionally be a large production facility
producing tens of thousands of tonnes per year.
However, new technology is becoming available to
enable wood pellet production on a smaller scale
(hundreds to a few thousand tonnes per year).
Wood pellets are now a major fuel source used in many
parts of Europe (Sweden, Austria, Norway, Germany,
Denmark, France) as well as in the US and Canada.
Wood pellets are made to a strict standard in terms of
size, moisture content and energy density. This is a
major advantage over the main biomass alternative,
wood chips, which can vary significantly in size andmoisture content between suppliers and from batch to
batch. The low moisture content of wood pellets also
reduces the relative cost of fuel transportation since less
water is present, and they are easier to transport and
store than wood chips. The main disadvantage of wood
pellets is that, for the same energy content, they will
generally cost about twice as much as wood chips.
Automatic Biomass Heating
Automatic wood heating using either wood chips or
wood pellets is now an established and mature
technology across Northern Europe, displacing imported
fossil fuels, creating local jobs within communities and
playing a central role in creating sustainable
development. There are now many hundreds of
thousands of heating systems operating in Europe, all
using locally sourced residues from woodland.
Biomass-fired central heating systems are now very
reliable, highly efficient and totally automated(automatic ignition, thermostatic control etc.) and offer
a level of convenience close to that of oil fired heating
systems but with substantial environmental and local
economic benefits. The share of biomass heating is also
increasing steadily as countries try to reduce their
dependence on imported fossil fuels.
Wood-fired boilers generally use standard radiators or
underfloor heating identical to those used by fossil fuel
systems. Although wood heating is common in the
domestic sector across Europe, it is best suited to largerhomes and commercial premises such as offices,
schools, colleges and factories. Boilers can sometimes
be converted such as older coal fired units as well as
those that have subsequently been converted to oil.
The main issues to consider when considering wood
heating will be location of fuel storage, delivery access
and connection to existing heating system.
The costs: Although we have seen in figure 2.4 that
wood fuel, and in particular wood chip, is a relatively
cheap source of fuel, the automatic appliances that usewood chip and wood pellet fuel are considerably more
expensive than the equivalent oil or gas appliances.
In terms of overall costs of a biomass boiler installation,
as with any heating system, the cost will be site specific.
However, as an indication the costs for the biomass
boiler and silo/chip feeding system will range between
4,000 to 5,000 + vat for a domestic pellet boiler (circa
12-20kW) and silo through to perhaps 8,000 +vat for a
wood chip boiler and chip extraction system for a large
farm house (circa 40kW) for example.
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However, capital grants are now available for both
commercial and domestic systems which could be
between 25% and 40% of the cost of the system
depending on site location and status (e.g. community
projects can receive higher grant funding). As the
systems get larger, the variation of cost is largelydetermined by the complexity of the fuel handling
system. As a basic rule of thumb, the boiler and fuel
handling equipment for systems in excess of 50kW
would be in the region of 100 - 120 per installed kW,
i.e. a 100kW system would cost in the region of 10,000
- 12,000. This would not include the cost of
construction work (e.g. fuel bunker) or installation.
Wood Chip Boilers
Figure 2.8 shows a picture of a commercial underfed
wood chip heating system with fully automated
thermostatic control. The auger feed mechanism which
transports the woodchips into the combustion chamber
can be seen. This mechanism allows a precise fuel feed
rate to the system. The air is supplied by the
combustion fan, which allows the amount of air to be
precisely controlled, ensuring optimum air-fuel ratios to
be maintained over a wide range of output, ensuring
the system runs at high efficiencies. We can also see the
control panel on the wall and the water jacket
surrounding the combustion chamber.
Wood Pellet Boilers
The principal advantage of wood pellets over wood
chips are the uniform size, the ease of handling in that
pellets will flow, and their uniformly low moisture
content. This combination makes pellets extremely
convenient for the consumer. The only realdisadvantage is price, as there is a significant
manufacturing cost for pellets. The cost per tonne of
pellets will generally be about twice that of chips,
although the energy content per tonne of pellets is
about 20% higher than seasoned wood chip as the
moisture content is lower.
Wood pellet burners are highly automated and are well
suited to meet variable load demands such as for a
school, where heat is required perhaps only 10 hours
per day, 5 days per week during the heating season. Allpellet appliances have thermostatic controls and can be
operated on a timer. The level of automation is
equivalent to oil fired heating systems, but wood pellets
have added environmental and local economic benefits.
Because the rate of fuel feed and amount of
combustion air is controlled precisely, pellet appliances
achieve very high efficiencies (typically 85-90%),
comparable to that of an oil system. They have lower
emissions, no tar build up in the chimney and less ash
deposition than wood chip boilers.
The cost of wood pellets on an equivalent delivered
energy basis is generally less than that of oil, although
the price of oil fluctuates significantly. A wood pellet
heating system itself will be more expensive than an
equivalent oil-fired heating system. Although wood
pellet fuel is fairly new to the UK, there are now a
number of UK suppliers, including one Devon based
manufacturer of wood pellets.
Automatic pellet stoves
Pellet stoves are fundamentally different from
traditional wood stoves in the fact that they are totally
automated - which means that they offer much more
convenience to the customer on the one hand, but are
far more complex in their operation and maintenance
on the other.
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Figure 2.8
A commercial underfed wood chip heating system.
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As we have seen, pellets are of small uniform size and
shape and low moisture and so burn easily. They also
flow freely and so in many ways wood pellet stoves are
closer to oil-fired central heating appliances than to free
standing traditional wood burning stoves. Pellet stoves
have the following advantages over traditional woodburning stoves:
Automatic ignition.
Thermostatic control.
Clean, easy to use fuel.
Very high efficiency 85-90%.
The main heat transfer mechanism is by convection
(from an air fan) rather than radiation, which is the
usual mechanism for a wood stove where the outer
casing becomes very hot and radiates heat.
There are now a variety of brands of appliance on the
market in many parts of Europe and North America,
and some models are now being imported to the UK.
The style of stoves vary from modern, almost futuristic
appliances to more traditional looking models. Two
different models are shown in Figures 2.9 and 2.10.
However, all pellet stoves operate on similar principles.
The cost of a pellet stove will typically be from 1400 to
well over 2,000 depending on model, which is
generally more expensive than the majority of log
stoves. However, capital grants of 600 are currently
available under the Governments Clear Skies
programme. In addition, this cost may be off-set by the
fact that the appliance will generally be operating at
about 90% efficiency, and hence fuel will be used very
economically. Additionally, the pellet stove offers a
much higher level of convenience and ease of operation
not found with a conventional log stove.
The Five Steps Towards Evaluating
a Viable Wood Energy System or
Business
Assessing the heat load and current fuels
Estimating the potential wood resource
Calculating costs
Environmental requirements
Planning and local issues
Step 1 - Assessing the heat load and usage
of current fuels
It is important when evaluating the potential for either
installing a biomass heating system or assessing
whether you have wood and other biomass resources
suitable for fuel, that you make an accurate estimate of
the current heating system. If your building is heated by
mains natural gas and the boiler is less than five years
old, it will be much more difficult for the economics to
work in favour of biomass. If however you are not on
mains gas and are using coal, oil, electricity or LPG as a
fuel and the boiler is more than 5 years old, then the
economics are likely to be more favourable.The following questions will help when talking with
potential biomass heating companies about a potential
scheme.
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Figure 2.9
Modern style pellet
stove.
Figure 2.10
More traditional style pellet
stove.
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Key Questions for Biomass Heating Systems
1. Is the heating system for a purely domestic load or
will there also be office, industrial or leisure sector
heat demand as well? If the heating load is spread
throughout the day then biomass heating can be anattractive option.
2. What is the current energy expenditure for fuel?
Having bills for the last full year would be a big help
here. What are the maintenance costs for your
current heating system?
3. If you are reviewing options for a larger boiler
system (i.e. non-domestic), do you have reasonable
access both for installing a new biomass boiler
system and bringing in wood chip and/or wood
pellet fuel? This is not an issue for domestic wood
pellet systems.
Key Questions on the Current Fuel Supplies
1. Is your current fuel mains natural gas, LPG, oil,
electricity, coal or a mixture of several of these?
2. Have you assessed all energy efficiency options
recently in order to reduce your fuel demand?
3. Are there any changes likely to your situation which
could increase the heat load in future (i.e. business
expansion, home extensions, or a new leisure
centre)?
Modern automatic biomass heating systems come in all
sizes, ranging from 6kW to greater than 1000 kW but
sizing a system accurately can ensure that cost-
effectiveness is maintained. As long as you have utility
bills for a 12-month period, a reputable biomass
heating supplier will work out the size of heating system
needed.
Step 2 - Potential Wood Fuel Suppliers or
wood for own use. How to estimate the
potential
In Devon and throughout the South-West there is plenty
of fuel available to supply both current and likely futuredemand for many years. This includes the assumption
that many woodlands are not managed due to the low
price of timber. Obviously if prices were to rise, and an
expanding biomass energy market would contribute to
that, woodland coming back into management would
bring even more resources into the market. For wood
chips, ample supplies are available for example from
the South West Wood Fuels Ltd, a co-operative of
landowners, foresters and others.
While UK produced supplies of wood pellets are morelimited and supplies have to be imported from
Scandinavia and Canada, a domestic wood pellet
production fuel cycle is being developed for the South-
West. Ample supplies of raw materials for wood pellets
(e.g. sawdust) are available.
Key Questions for Wood Fuel Supply
1. Are there local sources of wood chips and wood
pellets? Do you have your own sources from timber
management?
2. What tonnage of wood supplies or other biomass
resources do you have available?
3. What moisture content and consistency of content
do you have?
4. If you own woodland that is currently unmanaged
or only lightly managed, what resources might you
have available if it was managed and the market for
wood chips/fuel available?
For your local supplier of wood fuel contact South West
Wood Fuels 01398 324558.
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Step 3 - Costs
The fuel for modern biomass heating systems is
generally cheaper than fossil fuel based equivalents.
Wood chips can be around half the costs of heating oil
or LPG. For mains gas the margin is smaller, while for
coal and electricity the margin may be even greater.
Evaluating the costs will depend on local contracts and
proximity to fuel sources.
The capital costs of biomass boilers are higher than the
equivalent oil/LPG boilers and electrical heating
systems. However, the lower fuel and running costs will
pay back the difference over a number of years. How
long can only be determined by site-specific
assessments which will determine the costs of
conventional fossil-fuel based systems and local wood
fuel supplies.
For larger non-domestic systems the capital cost per
kilowatt of heat output is lower at around 100-200 per
kilowatt heat output. For example a 100kW system
heating a primary school is likely to cost between
10,000 and 20,000 depending the amount of
infrastructure/building work required. Capital grants to
encourage the development of clusters of commercial
biomass heating systems are now also available.
Step 4 - Environmental Requirements
Automatic wood heating systems are highly efficient
and emit very few pollutants. Equipment meeting the
European Standard on boiler efficiency (EN 303-5) will
emit no visible smoke whatsoever, apart from an initial
start up.
Step 5 - Planning and Local Issues
Automatic wood heating systems are a direct
replacement for conventional fossil fuel systems. They
are generally of larger physical dimensions and fuel
storage requirements are greater. However, for all but
larger industrial scale applications, the planning
requirements are similar to fossil fuel systems.
For larger systems it is advisable to consult with local
residents, the community and planning officers over the
likely impact of fuel transport and delivery movements.
Case Study 1:
Pinkworthy Barn, Oakford, Devon
Automatic Wood Chip Heating
Project Details
Pinkworthy Barn was used as workshops up until 2001
and was heated using a combination of electric heaters
and wall mounted LPG burners. During 2001 the 250
square meter workshops were converted to offices and a
radiator and underfloor system was fitted throughout.
A new wood chip boiler was specified and installed
which has sufficient capacity to heat both the offices
and the neighbours swimming pool. Enough spare
capacity is available to cater for future additional space
heating loads, which includes an existing large house
and workshops and a
further three
bedroom house.
The subterranean
boiler house includes
an 18m3 fuel silo with
a hinged roof to
enable easy dumping
of chip using a fore-
end loader or
agricultural tipping
trailer. Locally grown
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W O O D F U E L
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wood is chipped using a fuel-
wood chipper to provide dry
fuel of a consistent quality and
particle size.
The boiler is separated fromthe existing buildings by 15m
and so twin heating pipes were
laid underground between
them. The pipes are encased in
a flexible insulated conduit
similar to large drainage pipe
and have a very low heat loss. The boiler therefore is
able to work effectively at large distances.
How it Works
The silo is a 3m square by 2m deep block-workconstruction with a central revolving agitator with two
sweeper arms. An auger, in an open inclined trough,
receives chip from the sweepers and conveys it into the
boiler room where the auger continues within a closed
tube. The chip is dropped through a rotary valve seal
into a horizontal stoker auger at ground level which
feeds the boiler with fuel on demand.
The boiler and feed system is operated by the electronic
controller which can be interrogated, via a phone
connection, by a remote computer. The boiler hasseparate fans for primary air, secondary air and exhaust
gas extraction, all of which are operated by the
controller.
The feature that enables the
controller to work so well is
the oxygen sensor in the flue.
Using the information this
provides, the controller can
vary the fuel and air supply
rates to allow the most
efficient burning of the fuel,
while giving the heat output
from the boiler that is
required at that time. An
exhaust cyclone is fitted as an option on the flue which
makes any fine dust particles drop out of the gases for
periodic collection.
On startup from cold some smoke is emitted for a short
time, but once under normal running conditions theexhaust is clear and, using correct quality fuel, the
emissions are within the strict Austrian and UK
regulations for pollution.
Maintenance
Once a week the ash gate is revolved to let ash drop
from the combustion chamber into the ash store. Then
at intervals of approx. 4-6 weeks (dependant on usage)
the ash store is emptied. Other routine mechanical
service items are attended to on a longer periodic
schedule, such as greasing points on auger bearings.At two points within the heating season (suggested by
manufacturer) the dust from the cyclone is emptied and
at the same time the heat exchanger tubes of the boiler
are swept.
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W O O D F U E L
Technical DetailsBoiler Binder - RRK 49-70
Rated Heat output 70kW
Fuel moisture content
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28 A R E N E W A B L E E N E R G Y G U I D E F O R D E V O N 2 0 0 4
E N E R G Y C R O P S
Special energy crops such as short rotation coppice willow (above), rape seed, sugar
beet and miscanthus grass can be grown to be combusted for heat and power, or
processed to make bio-diesel and bio-ethanol.
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Highlights With significant surplus agricultural land available,
and pressure rising to reduce power and transport
sector CO2 emissions, there is an opportunity for
energy crops to have an important role in the UK
energy mix.
Energy crops include those grown for wood and
grass products which can be gasified or combusted
for the heat and power market, and those such as
rape seed and sugar beet which are grown for thebiofuels market.
The economics of energy crops are heavily
dependent on subsidy regimes and in early 2003
were marginal for most growers.
If biofuel duty tariffs are reduced further and grants
increased for crops such as fast-growing willow and
miscanthus grass, the market could expand very
quickly.
Around 1500 hectares of short rotation coppicewillow has been established in Yorkshire, with 400
hectares of miscanthus grass being established in
East Anglia in 2003.
Parts of Devon would be suitable for energy crops if
the market conditions were attractive.
A demonstration biomass gasification plant being
developed at Castle Cary, Somerset, has indicated its
wish to use energy crops as a fuel in future.
What are Energy Crops?Energy crops are specially bred and grown by farmers
for use by the energy industry. The crops include
miscanthus grass, short rotation poplar and willow, rape
seed, sugar beet and cereals. They are used to produce
heat and electricity, as well as processed into liquid
fuels for the transport and chemicals industries. Special
growers grants are available for short rotation coppice
(SRC) to establish the crop, while reductions in the fuel
duty levy are available for bio-diesel and bio-ethanol
(currently 20p/litre less than conventional oil-basedfuels).
The key benefit of energy crops is that the energy
expended in growing them (in planting, herbicides,
harvesting, drying the crop etc) is much less than that
released when they are burnt. The rest comes from
energy taken in from the sun during growth. Estimates
of this energy ratio (energy used to produce the crop
compared to the potential energy from the crop) for SRC
and miscanthus vary from about 1:10 to 1:90, with a
most likely figure of 1:20. This compares with around
1:7 to 1:10 if traditional arable crops were burnt in a
similar way and with 1:2 to 1:4 for bio-diesel.
In addition, these are environmentally beneficial crops.
Over the whole cycle they are virtually carbon neutral.
Studies have identified real potential benefits to
biodiversity and the potential to develop integrated pest
management strategies. Energy crops are a good
example of sustainable agriculture.
Originally it was assumed that to meet the
Governments 10% renewable energy target by 2010
some 500-1000 MWe of biomass generation would be
needed. This would need as much as 125,000 hectares
of energy crops. Given the poor economic state of UK
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E N E R G Y C R O P S
Chapter 2.2
Energy Crops
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Miscanthus is planted in spring and canes produced
during the summer are harvested in winter. The lifetime
of the crop is usually around 15 years. Yields build up
over three years to a peak. Yields from a mature crop
have exceeded 13 odt/ha/yr in experimental sites, and
20 odt/ha/yr in some years.
Lowland agriculture sites with deep, moisture retentive
soils are regarded as the best growing options. While
there is only limited experience of growing the crop so
far, 400 hectares is being grown in East Anglia to feed
into a power plant for testing purposes. Planting using
potato planting machinery has been carried out
successfully.
While there are currently uncertainties over the market
for the energy crops in power plants, there are three
promising developments:
It seems likely that the ARBRE gasification scheme inYorkshire will be bought by an additional company
and the technical problems overcome. This would
bring confidence back to farmers.
Changes to the rules for co-firing of biomass and
coal in coal-fired power plant may stimulate a
market for energy crops.
A demonstration biomass gasification plant
developed by Bronzeoak Ltd and located at Castle
Cary, Somerset, will likely use locally grown energy
crops, within 3-4 years. It is supported by the
Department of Trade and Industry (DTI).Action Points
While there is uncertainty over the pace and
direction of energy crops schemes for the heat and
power sectors in the UK, the potential for a
significant shift to energy crops remains.
What is currently missing for energy crops is a clear
and growing market in the power sector for the
product, and more attractive economics for
establishing and growing the crop.
Farmers should keep a watching brief through theNational Farmers Union (NFU) who have several
non-food crops specialists and who are lobbying
both the UK Government and European Union for
more attractive conditions to encourage growing.
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E N E R G Y C R O P S
Under the ECS DEFRA will pay the following grants to help
establish the crop:
For short rotation coppice (poplar or willow):
An enhanced rate of 1600/ha on eligible agricultural
land which is currently forage area for the purpose of the
IACS area aid application, not being AAPS eligible land, for
which livestock premia are claimed. This means that the
forage land must have been declared as part of the
current or previous years IACS application and claims
made to one or more of the Beef Special Premium
Scheme (BSPS), Hill Livestock Compensatory Allowance
(HLCA), Suckler Cow Premium (SCPS) or Sheep Annual
Premium (SAPS) in the current or previous scheme year.
A standard rate on other eligible land, i.e. arable land,
non agricultural land and land which forms part of an
agricultural holding but is neither arable or forage of1000/ha.
For miscanthus:
A grant of 920/ha for establishing the crop on land
which forms part of an agricultural holding.
Set aside land: These crops are permitted non-food crops on
set aside land. Land may be planted under the Energy Crops
Scheme and continue to receive set-aside payments under the
Arable Area Payments Scheme (AAPS) - providing the
conditions of both schemes can be met.
There are also grants of up to 50% to establish Producers
Groups to organise farmers in a region.
Contact: Government Office of the South-West -
Tel: 0117 900 1923 Fax: 0117 900 1905
Email: [email protected]
Establishment and other Grants under the Energy Crops Scheme (ECS)
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Liquid Biofuels
The UK transport system, in line with the transport
systems of most developed countries, is based almost
entirely on oil. Personal vehicles mainly use petrol and
diesel, refined from petroleum products, though a smallbut growing number of vehicles based on natural gas
are entering the UK fleet. Alternatives to fossil fuels are
available, at a price. At present these include bio-diesel
and bio-ethanol.
Brazil uses a 24% bio-ethanol blend in all gasoline fuels,
while in the USA some 12% of cars are powered by
biofuel blends. Both markets have been stimulated by
attractive tax concessions. Brazil originally set up its
bio-ethanol market to support its massive sugar
industry, while the US system was specifically to support
mid-West farmers seeking alternative outlets for cereal
crops.
Bio-diesel comes from crops such as rape-seed oil. It can
be used either as a 100% bio-diesel or as a blend with a
proportion of bio-diesel content. While countries such
as Germany, France and Sweden have
encouraged the development of a
100% bio-diesel fuel market, others
such as the UK are more supportive
of a blended fuel market. The UK
company Greenergy are the market
leaders, providing a 5% bio-diesel mix
with certified carbon reductions for
fleet managers who wish to switch
fuels. Responding to the potential
carbon benefits from bio-diesel, the
Treasury introduced a fuel duty
reduction of 20p/litre in 2001. This
has been insufficient to encourage
bio-diesel production in the UK, but
it has encouraged the recycling ofwaste oils such as chip fats. A growing
network of garages now stock
blended bio-diesel in Yorkshire.
Rix BioDiesel is one of the market
leaders in this new market (see www.rixbiodiesel.co.uk ).
Bio-ethanol has only recently entered the equation as a
potential alternative fuel. Companies such as British
Sugar and Cargill have been lobbying for fuel duty
incentives. British Sugar is looking for alternative
markets for sugar and cereals, given that subsidies for
farmers to grow sugar beet are on the way out. While
the energy equation and likely carbon reduction
benefits for bio-ethanol were in some doubt, the
Treasury was persuaded to allow a 20p/litre fuel duty
reduction from April 2003.
British Sugar has indicated that if the economics are
attractive enough for bio-ethanol they would be
prepared to invest 60 million in production facilities.
This would produce 100,000 tonnes of bio-ethanol a
year, using cereals or sugar beet as raw material. Theyargue that there is around a 50% CO2 reduction benefit
compared to petrol. At a 5% inclusion level in the liquid
transport fuels mix this would save 2.3 million tonnes
of CO2 per year, and create 20-30,000 jobs, many in
rural areas.
European Developments
As well as UK fuel duty developments
for liquid bio fuels, there have also
been European developments. These
include a draft Directive on biofuelsand production payments for
farmers.
The European Commissions mid-
term review of the Common
Agricultural Policy (CAP) provided an
opportunity to give a per hectare
payment for non-food crops grown
for electricity production or transport.
However, this was proposed for
existing areas of production only,hence doing little to encourage a new
industry. It was also set at a relatively
low level.
32 A R EN EW A BL E E NE RG Y G U ID E F O R D EV O N 2 00 4
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Figure 2.11
5% blended bio-diesel based on rape
seed on sale at supermarket forecourt.
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The EU Directive on biofuels has been weakened. The
key proposal that each Member State should substitute
2% of its road fuels with biofuels by 2005, rising to
5.75% by 2010, has been turned into indicative only
rather than binding targets. The European Parliament
are keen to toughen this position and negotiations were
continuing as this Guide went to press.
UK Bio-fuel Production
Reactions to the 20p/litre fuel duty reduction for both
bio-diesel and bio-ethanol has been one of
disappointment. The National Farmers Union thinks
that the duty reduction may stimulate a few small-scale projects mainly using reclaimed fuels (such as old
chip fat), but its not enough to take biofuel production
into the mainstream. Companies such as Greenergy
and British Sugar support this view, and have been
lobbying for fuel duty reductions of 26-30p/litre. With a
fuel duty reduction of 25p/litre Greenergy predicts that
bio-diesel use would reach 3% by 2010, with between a
third and half of this coming from virgin rather than
reclaimed oil. A Duty cut closer to 30p/litre would be
needed to boost production from virgin oils
significantly. Cargill wants to build a bio-diesel
processing plant in the UK but thinks that 30p/litre is
the minimum fuel duty reduction to make this viable.
Next Steps and Action Points
In early 2003 the economics of bio-diesel and bio-
ethanol were marginal for UK production both on the
crops and processing sides. Current fuel duty reductions
via the Treasury seem too small to allow companies tocommit to UK production and for farmers to have a
decent energy market for rape-seed, cereals or sugar
beet. Mainstream oil/chemical company production is
unlikely to emerge until fuel duty relief hits 25-30p/litre.
Farmers should monitor this situation however, as
modest changes to the current fuel duty regime might
swing the balance in favour of local production. So far
the only UK production of bio-diesel seems to be based
around backyard efforts at reclaiming old cooking oil.
The disadvantage of these are question marks over
engine warranties and ensuring quality control.
Action Point
Fleet managers with local authorities and the
private sector can make a modest but clear carbon
reduction effort by opting for the blended Global
Diesel produced and sold by Greenergy, plus other
blends sold by Rix BioDiesel.
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Figure 2.12
A Tesco home delivery truck being filled up with 5%
blended bio-diesel.
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C O M B I N E D H E A T A N D P O W E R
Combined Heat and Power plant is an installation where there is simultaneous
generation of usable heat and power (electricity) in a single process.
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Highlights Combined Heat and Power (CHP) systems based on
wood and wood residues are available in a range of
technologies in the UK.
These include technologies such as a conventional
gasifier and internal combustion engine/gas turbine,
a near market Stirling engine, a high speed steam
engine and an organic Rankin Cycle.
A small number of biomass CHP systems are
operating in the UK, with a much larger number
overseas.
At present none is truly commercial, though this
situation could improve in the near future.
Review of Biomass CHP systems
A recent review of biomass CHP systems in the UK
provides the basis of the following review1. Since the
conclusions of the