217. ivy bridge house: greenergy international ltd; address

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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

2 0 0 4


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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


I N T R O D U C T I O N

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.



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.



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.

10 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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What it Means

Terminology and Glossary



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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E N E R G Y F R O M B I O M A S S


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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.


E N E R G Y F R O M B I O M A S S

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.


W O O D F U E L

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


W O O D F U E L

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.


17/9217A 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

W O O D F U E L

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


18/92

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.


W O O D F U E L

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)


19/92


20/92

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.


W O O D F U E L

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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22/92

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.


W O O D F U E L


23/92

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.


W O O D F U E L

Figure 2.8

A commercial underfed wood chip heating system.


24/92

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.


W O O D F U E L

Figure 2.9

Modern style pellet

stove.

Figure 2.10

More traditional style pellet

stove.


25/92

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.


W O O D F U E L


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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


W O O D F U E L


27/92

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.


W O O D F U E L

Technical DetailsBoiler Binder - RRK 49-70

Rated Heat output 70kW

Fuel moisture content


28/92


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.


29/92

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



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.



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.



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.



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

217. ivy bridge house: greenergy international ltd; address

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