Wind Power in the UK · Wind Powerin the UK A guide to the key issues surrounding onshore wind power development in the UK Wind Power in the UK Sustainable Development Commission

Wind Power in the UK

A guide to the keyissues surrounding

onshore wind powerdevelopment in the UK

Win

d Pow

er in th

e UK

Sustainable Developm

ent Comm

ission May 2005

Acknowledgements

Many individuals and organisations assisted uswith the compilation of this report and theCommission is extremely grateful to all of them.

The views expressed are those of theSustainable Development Commission.

Cover image: Niall Olds, Enviros

Published: May 2005 (revised November 2005)

Printed on material that contains a minimumof 100% recycled fibre for uncoated paper and75% recycled fibre for coated paper.

To order more copies of this report, to ordercopies of the booklet, Wind Power, YourQuestions Answered, or to find out more aboutthe work of the Sustainable DevelopmentCommission, visit our website at

www.sd-commission.org.uk

PB11144

“The most comprehensive study of windenergy in Britain”

Geoffrey Lean, Independent

“A recent report by the government’sSustainable Development Commission washailed by the industry as a breakthroughbecause it showed wind power was becomingprice competitive with other fuels.”

Mark Townsend, Observer

“...the most informative, comprehensive,balanced and readable report on the subjectI have ever read”

Prof. Leon Freris, CREST Loughborough University

“Because of the highly charged debate onwind power the report has been peerreviewed, like a scientific paper, to give itgreater credibility so it can be used byplanners as an authoritative document”

Paul Brown, Guardian

DEFRA 10528 Wind Energy Cov.qxd 14/12/05 13:01 Page 1


Wind Power in the UK isustainable development commission

Foreword

In my capacity as the immediate past Chairman of RCEP, and Chairman at the time of the RCEP EnergyReport, I would like to warmly welcome the SDC’s report on wind power in the UK as one that makes asignificant contribution to an important area of public debate. All the RCEP's scenarios in its EnergyReport envisaged a large role for wind in meeting the challenge of climate change. The RCEP remainsconvinced of the need for this role, as part of a much broader Climate Change Programme.

I am pleased to note that the SDC report confirms that wind is both the cheapest and one of the mostabundant of the UK's renewable resources. At current levels of gas prices, and certainly if credit is givenfor its carbon-free status in line with current Government estimates of the social cost of carbon, it isalready cost-competitive with gas-fired electricity on the best onshore wind sites, and seems likely tobe the cheapest of all forms of power generation by 2020 on such sites, even without a carbon credit.In addition, the supposed additional system costs of wind have been much exaggerated in somequarters and it is encouraging to see that this report shows, on the basis of rigorous analysis, that theyare in fact very modest.

The RCEP also expects that in the UK wind is likely to substitute for coal-fired generation in the shortterm and perhaps gas in the medium term. This means that it will reduce carbon emissionssubstantially.

Another frequent misunderstanding related to wind is the implication of its variability. In fact, withmodern meteorology, wind is very predictable over the time scales relevant for balancing the electricitysystem. Its variability means that it cannot displace fossil plant MW for MW, but at penetrations up to20% of electricity generation it can displace fossil plant at around 20% of installed wind capacity. Thecarbon penalty for having to have additional conventional plant on reserve duty to compensate for thevariability of wind (which is in any case usually predictable) is very small.

The visual and landscape impacts of wind remain of concern to the RCEP, and to many people who lovethe UK countryside. This concern must be taken seriously and steps taken not to allow wind farms tospoil sites designated for their beauty. But all forms of power generation have negative environmentalimpacts, and climate change will have the most serious impacts of all.

Sir Tom Blundell FRS FMedSci

ii Wind Power in the UK sustainable development commission

Executive Summary

Wind power development arouses strongopinions. For the general public, a high level ofsupport nationally for wind power can becontrasted with opposition at the local level.This situation presents local planners,councillors, and communities with a difficult task– to assess the needs of the wider environmentagainst local concerns. Information about thecomplexities of wind power generation – itscosts, intermittency issues, effects on theelectricity network, noise, ecological andlandscape impacts among others – is thereforeessential for considered decisions to be made.

The aim of this report is to outline the mainissues relating to onshore wind power andcomment on their validity from a sustainabledevelopment perspective, in line with theprinciples outlined in the UK’s new Frameworkfor Sustainable Development.

TargetsThe UK has committed itself to working towardsa 60% reduction in CO2 emissions by 2050, andthe development of renewable energytechnologies such as wind is a core part ofachieving this aim. UK wind resources are morethan enough to meet current renewable energytargets – the generation of 10% of UK electricityfrom renewable sources by 2010, and anaspirational target of 20% by 2020 – and thereare no major technical barriers to meeting thesetargets.

IntermittencyWind blows at variable speed, variable intensityand sometimes not at all. But this variability isnot a problem for the electricity grid. Wind isaccurately forecast over the timeframes relevantto network operators and other marketparticipants. Increasing the proportion of windpower in the electricity system does not requiregreater “back up” capacity, as is often believed,but it does slightly increase the cost. The greater

the proportion of wind on the grid the lower its“capacity value”, and the lower the quantities ofconventional technology it displaces.Nevertheless it continues to reduce carbonemissions.

CostsThe generation costs of onshore wind power arearound 3.2p/kWh (+/-0.3p/kWh), with offshoreat around 5.5p/kWh, compared to a wholesaleprice for electricity of around 3.0p/kWh. Theadditional system cost is estimated to be around0.17p/kWh, when there is 20% wind power onthe system. Generation costs are likely todecrease over time as the technology improves,but this will be balanced against increased costsfor integrating higher levels of wind generationinto the system.

Environmental impactsAs a carbon free source of energy, wind powercontributes positively to the UK’s effort to reduceour carbon emissions to tackle the threat ofclimate change. The impact of climate changeon the landscape will be radical, and thereforethe visual impact of a wind development mustbe considered in this context. To some, windturbines are a blot on the landscape whereas toothers they are elegant workhorses, but thisreaction is highly subjective. However, there arefar fewer landscape and environmental impactsassociated with wind turbines than with otherenergy generation technologies, although theirdevelopment is often in areas that have not hadsuch developments in the past. Winddevelopments do not have long lastingdecommissioning issues, as they can be replacedor removed quickly if necessary.

Wildlife and habitat impacts can be minimisedthrough careful project location, designmeasures, and appropriate constructiontechniques. Environmental Impact Assessmentsmust be comprehensive, and thoroughly explore

Wind Power in the UK iiisustainable development commission

Executive Summary

all the potential disadvantages so these can beproperly mitigated. Not all sites will beappropriate for wind developments, anddesignated areas should continue to receive ahigh level of protection.

Community engagementA key factor in a successful wind development isthe involvement of the local community at allstages. This will ensure that the community isinvolved in exploring ways of mitigating anypotential environmental or social impacts – suchas overcoming any effects on TV transmission.Communities often perceive noise from turbinesto be a potential problem, but the noise fromthe moving parts has reduced substantially asthe technology has advanced, and communitiesoften find that noise is not a problem.

Planning procedureThe planning policy environment and consentsprocedure need to continue to improve toenable renewable energy development. There will continue to be barriers to somedevelopments because of their impact on radarand aircraft radio navigation systems, but thiscan be resolved in the pre-planning stage. TheUK has some of the strictest policies in place toprotect against interference of radar andaviation, and these must be justified.

The Sustainable Development Commission (SDC)hopes that this report will be used to ensurethat good practice is followed when new windpower developments are being considered andcalls on all stakeholders to play their full part toensure that the benefits of renewable energyare realised through careful design andconsultation.

SUSTAINABLE DEVELOPMENT COMMISSIONMAY 2005

Brandon Clements, Rhona Earnshaw and Phoebe Brownturn on the Isle of Gigha ‘Dancing Ladies’ providing the130 strong community with energy and independence.

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Wind Power in the UK 1sustainable development commission

Contents

1 INTRODUCTION 3

1.1 The aim of this report 3

1.2 Considering the big picture 3– sustainable development

1.3 UK perspective 5

1.4 Technical annexes and glossary 5

2 DELIVERING CLEAN ENERGY: 6THE ROLE OF WIND

2.1 Climate change and the need for action 6

2.2 Emissions reductions targets 7

2.3 Renewable energy targets 9

2.4 The role of wind power 11

2.5 UK wind resources 13

2.6 Current and future wind capacity 16

3 WIND POWER TECHNOLOGY AND 17NETWORK INTEGRATION

3.1 Wind turbine technology 17

3.2 Energy balance 18

3.3 UK electricity supply system 19

3.4 Balancing the system 20

3.5 Capacity and flexibility of wind power 22

3.6 Displacement of fuel use and emissions 25

3.7 Limits on wind capacity 26

4 COSTS AND BENEFITS OF WIND 27

4.1 Background 27

4.2 Calculating generation costs 27

4.3 Wind power generation costs 29

4.4 Comparing wind energy to 30conventional generation costs

4.5 System costs from wind energy 31

4.6 Cost of UK support mechanisms 37

4.7 Alternatives to wind energy 38

4.8 Projected long-term costs for 40electricity generation

4.9 Drawing conclusions 41

5 WIND POWER AND PLANNING 44

5.1 Planning process for wind projects 44

5.2 Planning Policy 47

5.3 Current development plans 48

6 LANDSCAPE AND ENVIRONMENT 51

6.1 Background 51

6.2 Landscape change 51

6.3 Landscape and visual effects 52

6.4 Visual characteristics of wind farms 54

6.5 Designated areas 56

6.6 Public perception 56

6.7 Comparing landscape and 57environmental impacts

6.8 Land-take by wind developments 60

6.9 Achieving a long-term perspective 60

7 WILDLIFE AND ECOLOGY 65

7.1 Background 65

7.2 Habitats 65

7.3 Peat 67

7.4 Water 67

7.5 Birds 68

7.6 Protected mammal species 69

7.7 Bats 70

7.8 Good environmental assessment 70

7.9 The way forward 70

2 Wind Power in the UK sustainable development commission

Contents

8 NOISE 72

8.1 Background 72

8.2 How noise is measured 72

8.3 Wind turbine noise 72

8.4 Noise reduction 73

8.5 Noise levels in the community 74

8.6 Assessment of noise 74

8.7 Regulation of noise 75

8.8 Noise in perspective 76

9 WIND POWER AND THE COMMUNITY 79

9.1 Background 79

9.2 Public attitudes 79

9.3 Community concerns 83

9.4 Economic and community benefits 84

9.5 Public consultation 85

9.6 Lessons for success 89

10 AVIATION AND RADAR 99

10.1 Background 99

10.2 Radar 99

10.3 Aviation 101

10.4 Seismic stations 102

10.5 Regulatory process 102

10.6 International experience 103

10.7 Mitigation measures 104

10.8 Balancing priorities 105

11 TELECOMMUNICATIONS 106

11.1 Background 106

11.2 Television 106

11.3 Fixed radio links 107

11.4 Scanning telemetry systems 107

11.5 A solvable problem 107

12 THE PROCESS OF WIND FARM 110DEVELOPMENT

GLOSSARY OF TERMS 113


1 Introduction

1.1 The aim of this reportOur report is aimed primarily at thoseresponsible for making decisions about onshorewind power developments, including planningofficers, local councillors and local energy andsustainability officers. It is relevant to policymakers at all levels of government – includinglocal authorities, Regional DevelopmentAgencies, the Devolved Administrations and UKGovernment – and can also be used as a goodpractice guide by the wind and renewableenergy industry, environmental organisations,community groups and other stakeholders.

An information booklet has been published toaccompany this report to present the key issuesin a readily accessible format.

This report purposely concentrates on theonshore sector, where decision making isprimarily undertaken at a local level and wheredebate is strongest. However, many of theissues discussed are relevant to both on andoffshore development, and where this is thecase no distinction is made. The SDC recognisesthat there is growing understanding of anumber of environmental concerns specific tooffshore developments, but believes thesewould be best dealt with separately, as offshoredecisions are made centrally rather than locally.

The SDC has drawn on a wide body of research,supplemented by specially commissioned workand input from key stakeholders. The reportalso makes use of case study material, internalexpertise and access to a variety of governmentdata and analysis. The result is a report whichwe believe to be comprehensive in its scopeand we hope useful to those at the front line onthis issue.

The wind power industry in the UK is evolvingrapidly. It is hoped that by publishing this reportthe SDC can contribute to the planning andpolicy making process at all levels and therebyensure that good decisions are based on a goodunderstanding of the real issues.

1.2 Considering the big picture –sustainable developmentAny decisions the UK takes on the developmentof wind power and its place in energy policyneed to be placed within the context of theGovernment’s overarching policy to pursue andpromote sustainable development.

In March 2005, the UK Government and theDevolved Administrations published One future –different paths, the UK’s shared strategicframework for sustainable development. Thiswas launched in conjunction with the UKGovernment’s new strategy for sustainabledevelopment Securing the Future.


1 Introduction

A new framework goal sets out the purpose the UK Government and the Devolved Administrations aretrying to achieve:1

A set of five shared principles underpin this purpose and the framework requires that a policy “mustrespect all five principles” to be considered sustainable:

The goal of sustainable development is to enable all people throughout the world to satisfy theirbasic needs and enjoy a better quality of life without compromising the quality of life of futuregenerations.

For the UK Government and the Devolved Administrations, that goal will be pursued in an integratedway through a sustainable, innovative and productive economy that delivers high levels ofemployment and a just society that promotes social inclusion, sustainable communities and personalwell-being. This will be done in ways that protect and enhance the physical and natural environmentand use resources and energy as efficiently as possible.

Government must promote a clear understanding of, and commitment to, sustainable developmentso that all people can contribute to the overall goal through their individual decisions.

Similar objectives will inform all our international endeavours, with the UK actively promotingmultilateral and sustainable solutions to today’s most pressing environmental, economic and socialproblems. There is a clear obligation on more prosperous nations both to put their own house inorder and to support other countries in the transition towards a more equitable and sustainableworld.

Living Within Environmental LimitsRespecting the limits of the planet’s

environment, resources and biodiversity – to improve our environment and ensure that the

natural resources needed for life are unimpaired and remain so for future

generations.

Achieving a Sustainable EconomyBuilding a strond, stable and

sustainable economy which provides prosperity and opportunities for all,

and in which environmental and social costs fall on those who impose them (poluter pays), and efficient resource

use is incentivised.

Promoting Good Governance

Actively promoting effective, participative systems of

governance in all levels of society – engaging people’s

creativity, energy, and diversity.

Using Sound Science ResponsiblyEnsuring policy is developed and

implemented on the basis of strong scientific evidence, whilst taking into account scientific uncertainty (through the precautionary principle) as well as

public attitudes and values.

Ensuring a Strong, Healthy and Just SocietyMeeting the diverse needs of all people in

exisiting and future communities, promoting personal wellbeing, social cohesion and

inclusion, and creating equal opportunity for all.


1 Introduction

The framework identifies ‘climate change andenergy’ as one of four priority areas forimmediate action, shared across the UK. Inparticular, the UK Government and DevolvedAdministrations have committed to “seek tosecure a profound change” in the way that wegenerate and use energy, and in other activitiesthat release these (greenhouse) gases. Theyhave also recognised that they “must set a goodexample” and have undertaken to “encourageothers to follow it”.

In applying a sustainable development approachto wind power it is clear that we need to payparticular attention to:

• Accounting for the wider environmental,societal and health implications as well as theeconomics;

• Ensuring that climate change and security ofsupply issues are responsibly addressed;

• Basing decisions on strong scientific evidenceand ;

• Actively engaging all levels of society in thesedecisions.

1.3 UK perspectiveThe SDC is a UK-wide body, reporting to thePrime Minister and the First Ministers of theDevolved Administrations. This report reflectsthis remit, and covers wind power from a UKperspective. Where national distinctions exist,these are highlighted. However, where nodistinction is made, the term ‘Government’applies to the UK Government and/or to issuesthat are not devolved.

1.4 Technical annexes and glossaryAt the back of this report there are sometechnical annexes that give further informationon the issues covered in the main chapters. Afull glossary is provided at the end of this

document to explain technical issues and terms.A breakdown of the two main electrical units isgiven below.

Reports on energy issues very often usedifferent units of measurement, which can leadto confusion. Readers should be aware of thiswhen comparing data in this report to othersources of information.

Watt – measure of instantaneous power orcapacity:1 GW = 1,000 MW = 1,000,000 kW =1,000,000,000 W

Watt-hour – total energy over time (one wattexpended for period of one hour):1 TWh = 1,000 GWh = 1,000,000 MWh =1,000,000,000 kWh = 1,000,000,000,000 Wh


2 Delivering clean energy: the role of wind

Summary• There is now consensus that carbon dioxide emissions are causing climate change, and the

harmful effects are widely recognised

• The UK Government and Devolved Administrations have responded to the dangers of climatechange by promoting the development of renewable energy sources, including wind power, toreduce emissions of carbon dioxide and other greenhouse gases

• Government policy aims to obtain 10% of the UK’s electricity from renewable sources by 2010,with an aspiration to source 20% by 2020

• These targets form part of commitments to reduce the UK’s greenhouse gas emissions, with thelong-term goal of a 60% reduction in CO2 emissions by 2050

• The UK has the best and most geographically diverse wind resources in Europe, more thanenough to meet current renewable energy targets

2.1 Climate change and the need for actionThere is now wide international consensus thathuman activities over the last two centuries sincethe start of the industrial revolution haveinfluenced the global climate in a harmful way2.This harm will continue to grow, and coulddramatically accelerate, unless action is taken toreduce the emissions of greenhouse gases, suchas carbon dioxide (CO2), methane (CH4) andnitrous oxide (N2O), by very significant amounts.Greenhouse gases are emitted primarily from thecombustion of fossil fuels, intensive agricultureand other industrial processes. They trap solarenergy that would normally be radiated backinto space, causing average global temperaturesto rise. This will affect rainfall patterns and willresult in more frequent extreme weather eventsin the UK and across the globe. Highertemperatures will also lead to melting of thepolar ice caps and a rise in the temperature ofseawater, causing it to expand; these two effectswill cause sea levels to rise.

Detailed scientific information is available in thepublications of the Intergovernmental Panel onClimate Change3 (IPCC), the international bodyset up to research and report on the science of

climate change. The IPCC states that no morethan ten of at least 3,000 international climatescientists reject the idea that greenhouse gasemissions are causing the planet to warm. TheUK’s Chief Scientific Adviser, Sir David King,certainly agrees – in an article in 20044 he statedthat:

“In my view, climate change is themost severe problem that we arefacing today, more serious even thanthe threat of terrorism.”

Large areas of the world, including manydeveloping countries, are only a few metresabove normal sea level and will suffercatastrophic sea level rises as a consequence ofclimate change. This could lead to the massmigration of millions of displaced people, puttingfurther pressure on already strained resources.

The geographical position of the UK makes ithighly vulnerable to the consequences ofclimate change. Extreme weather events such asviolent storms and increased rainfall are alreadyshowing a pattern of change. Low lying, denselypopulated land in the south and east of the UK,



which is already sinking measurably due to longterm geological forces, is very vulnerable to anypotential rise in sea level.

2.2 Emissions reductions targetsInternational action to reduce greenhouse gasemissions is embodied in the Kyoto Protocol5.The greenhouse gases targeted for reduction arecarbon dioxide, methane, nitrous oxide,hydrofluorocarbons, perfluorocarbons, andsulphur hexafluoride. The emission targets arenot for the specific gases, but instead for acombination of the six gases weighted by therelative warming effect of each gas, known astheir Global Warming Potential; the higher thisfigure is, the more harmful the gas – see Table 1.

Carbon dioxide emissions come primarily fromtransport, business, housholds, and thecombustion of fossil fuels in electricitygeneration – see Figure 1. Although CO2 has theweakest global warming effect, the sheer scaleof emissions from human activities across theworld makes this gas the largest contributor toclimate change.

The Kyoto Protocol came into force in February2005. It covers 55% of global greenhouse gasemissions and is a legally binding commitment.The UK’s target is to achieve a 12.5% reductionin greenhouse gas emissions from 1990 levels,averaged over the period 2008-2012. Thisrepresents the UK’s share of a wider EuropeanUnion (EU) commitment. The Government hasalso set a national goal of a 20% cut in CO2

emissions by 2010. This was stated in the 2003Energy White Paper as the first step in astrategy to achieve 60% cuts in CO2 by 2050,and as part of the Government’s desire to showinternational leadership on this issue.

The Climate Change Programme announced in2000i contains a basket of measures throughwhich the Government intends to meet thesetargets. UK-wide measures include the ClimateChange Levy for business, the Energy EfficiencyCommitment for households, a commitment tothe EU Emissions Trading Scheme (EUETS), and araft of other measures to encourage renewableenergy and energy efficiency. The DevolvedAdministrations have separate plans to deal withdevolved matters.

Carbondioxide (CO2)

Methane(CH4)

Nitrousoxide (N2O)

288 ppm

848 ppb(0.848 ppm)

285 ppb(0.285 ppm)

372 ppm

1843 ppb(1.843 ppm)

318 ppb(0.318 ppm)

+1.5 ppm/yr

+7.0 ppb/yr

+0.8 ppb/yr

1

23

296

Fossil fuel combustion (oil, gas,coal)

Landfills; animal agriculture;losses to the atmosphere ofnatural gas during production,transportation, and use; coalmining

Agricultural soil management;fertilizers; fossil fuel combustion;industrial production of nylon

Pre-industrialconcentration

Presentconcentration

Rate ofconcentrationchange(1990-1999)

GlobalWarmingPotential

Principal UK sources

Table 1: Concentrations of principal greenhouse gases6

i The Climate Change Programme is currently under review and is expected to be updated during 2005.



Currently the UK is on course to meet its Kyotoobligations for a 12.5% cut in greenhouse gasemissions during 2008-2012. A large percentageof the reduction achieved since 1990 is due tothe commercially-led transition to gas-firedelectricity generation. On CO2, the latestGovernment projections show that under currentmeasures the UK will only achieve a reductionof 14% by 2010, compared to the 20% target,and more will need to be done if the target is tobe achieved. This is because for the last fiveyears CO2 emissions have stabilised aftersustained reductions during the 1990s – seeFigure 2. The scale of the task ahead should notbe underestimated; the Government expectscontinued upward pressure on emissions due tomore single-person households and continuedgrowth in demand for transport and newappliances. It will therefore be a significantchallenge for the UK to restart emissionsreductions and achieve its stated goals.

Figure 1: CO2 emissions by source, 20047

Sector

■ Power stations

■ Domestic

■ Commercial and public service; land use change and agriculture

■ Industry

■ Transport

■ Other sectors

29%

15%7%

25%

22%2%

Figure 2: UK CO2 and greenhouse gas emissions (MtC equivalent), 1990-20037/8

0

50

100

150

200

250

1990 1991 1992 1993 1994 1995 1996 1997

Year

MtC

1998 1999 2000 2001 2002 2003 2004

Carbon Dioxide All greenhouse gasses (CO2 equivalent)



2.3 Renewable energy targetsThe drive towards a low carbon economydepends heavily upon the successful stimulationof renewable energy technologies, and thesefeature strongly in the 2003 Energy White Paper.The principal source of CO2 is the burning offossil fuels, including those used for generatingelectricity - coal, natural gas, and to a far lesserextent oil. The chemical nature of the fueldetermines how much CO2 is produced duringthe process, with natural gas producingsubstantially less than coal or oil. Mostrenewable energy sources do not produce anyCO2, hence the Government’s stated intention toincrease their use substantially, particularly inelectricity generation.

The UK Government has set targets to increasethe percentage of renewable electricitygeneration in total supply. These call for 10% ofelectricity to come from renewables by 2010,with the aspiration of 20% by 2020. TheDevolved Administrations are committed tomaking an equitable contribution to thesetargets, and have set their own targetsaccordingly – these are summarised below. TheGovernment is also relying on the EnglishRegions to put regional policies and targets inplace.

The primary mechanism for meeting therenewable energy targets across the UK is aRenewables Obligation on suppliers – this isexplained in more detail in Box 1.

It is important to note that electricity representsabout a quarter of the UK’s consumption ofprimary energy, and is therefore only part ofoverall emissions. Transport and non-electric

heating together account for a much largershare of energy consumption and thereforeaction must also be taken to reduce emissions inthese areas as well.

ScotlandThe Scottish Executive is committed to makingan equitable contribution to the UK Kyotocommitment and is working with the UKGovernment to meet its targets for reducingemissions. On renewable energy, it has set itselfthe further goal of generating 18% of Scotland’selectricity from renewable sources by 2010 and40% by 2020. Given the substantial windresource available in Scotland and its leadingcompetitive position among renewable sources,wind generation will be a major contributor toachieving this target.

WalesThe Welsh Assembly has set a target of 4,000GWh to be produced from renewable energysources by 2010, in order to contribute to the UKnational target of producing 10% of itselectricity from renewablesii.

Northern IrelandNorthern Ireland has an existing target to source12% of electricity from renewables. However,the recent introduction of a Northern IrelandRenewables Obligation by the Department ofEnterprise, Trade and Investment in April 2005led to a decision to ‘decouple’ this target fromthe level of the obligation, which was set at6.3% by 2012/13. This will increase yearly froma level of around 1.5% in 2003.

ii DTI generating plant statistics do not disaggregate for Wales, so it is not possible to calculate what percentage this is oftotal generation.



There are a number of different ways of supporting renewable electricity generation, but after apublic consultation between 1999-2000, the Government decided that a Renewables Obligation wastheir preferred solution for the UK’s liberalised electricity market.

The Renewables Obligation (RO) was introduced in April 2002, and covers England and Wales. At thesame time, Scotland introduced the Renewables Obligation (Scotland), and Northern Ireland hasmore recently introduced its own obligation, both with different levels of requirement. As all threeObligations are similar in design, further reference to the RO in this report can be taken as applyingto the mechanism in general.

The RO requires electricity suppliers to source an increasing percentage of their electricity fromrenewable sources. The levels of the Obligation for England and Wales, and for Scotland, are set at10.4% for 2010/11 and 15.4% for 2015/16. The RO is in place until 2027, giving a clear signal ofcommitment to investors and developers.

Electricity supply companies can meet their obligation by: presenting Renewable ObligationCertificates (ROCs) to the regulatory authority; by paying a buy-out fund contribution equivalent to£30/MWh (in 2002, rising each year in line with the Retail Prices Index); or a combination of thetwo. ROCs are issued to renewable generators for each 1 MWh of electricity generated, and are thenbought by supply companies.

The RO is ‘technology blind’, meaning it does not favour one renewable technology over another. Theresult is that electricity supply companies will tend to choose the most cost-effective generationtechnologies, and for at least the next five years this will be primarily wind power, biomass andmethane recovery (from landfill or coalmines). The Government recognises that this can make itdifficult for less commercialised technologies to obtain investment and so it has a series of research& development and capital grant programmes to assist these technologiesiv.

Box 1

English RegionsThe Government expects the nine English Regions to play a key part in the delivery of energy policyobjectives at the regional level. A number of regions now have their own renewable energy targets for2010 and beyondiii.

iii For example: Greater London Authority, East Midlands Assembly, and South East England Regional Assembly.iv Further details of these technologies and programmes to assist them can be found on the DTI Renewables website at

www.dti.gov.uk/renewables

Renewables Obligation



Figure 3: Electricity generation by fuel source in 20047

2.4 The role of wind power

Electricity supply and renewablesIn 2004 total electricity sales in the UK werearound 325,000 GWh15. This was met primarilyby large, centralised power plants fuelled bynatural gas, coal and nuclear – see Figure 3 for abreakdown by fuel source. Renewables suppliedaround 3.2% of total supply in 2004, much ofthis from large hydroelectric power plants builtover the last 50 years and from the combustionof landfill gas. Figure 4 shows how totalrenewable electricity generation is broken downinto different sources for 2003, the most recentyear for which figures exist.

The Government has already indicated that thereis little scope for further development of largehydropower schemes, due to space andenvironmental considerations. The renewablestargets will therefore have to be met through acombination of other technologies, with themarket naturally focussing on those that are mostcost competitive. Until 2010, the most populartechnologies are likely to be wind power, biomass(used both for co-firing in conventional powerplants and in smaller, biomass-only plants), and

methane-recovery. Other technologies, such astidal, wave, and solar photovoltaics are likely toplay a small role, but their contribution in thelonger term could be considerable.

Government policy is to encourage thedevelopment of a wide range of renewables – asummary of the main technologies available isgiven in Box 2.

An increasing role for wind powerOnshore wind power is already one of thecheapest forms of renewable energy per kWh,with the potential for even further costreductions as the technology develops – seeChapter 4. Offshore wind is more expensive, butthe industry expects costs to come down overtime as experience is gained and the technologyis improved. Due to its low cost, currentpredictions are that electricity supply companieswill meet most of their Renewables Obligation to2010 from wind power. Assuming a wind powerutilisation factor, commonly referred to as the‘capacity factor’, of 30%v, 9,500 MW (9.5 GW) ofinstalled wind capacity will produce around25,000 GWh of energy, which when added to the10,000 GWh that is already generated fromrenewables, is about 10% of current UKelectricity sales and would therefore meet the2010 target, if electricity consumption remainsstable. In reality this target will be met from avariety of renewable energy sources, with onand offshore wind power as major contributors.

No substitute for energy efficiencyUsing less energy is one of the cheapest ways ofreducing carbon emissions – as discussed inChapter 4. If the UK were able to cut electricityconsumption whilst increasing renewable energycapacity, the effect on emissions would be moresubstantial, and future renewable energy targetswould be easier to meet. The SDC believes thatenergy efficiency and the development ofrenewable energy go hand in hand.

32.7%

1.1%1.9%

19.1%

3.2%

41%

1%

■ Coal

■ Oil

■ Gas

■ Nuclear

■ Renewables

■ Other fuels

■ Net imports

v See Chapter 3 for a discussion of capacity factors.



Renewable Energy Sources in the UKRenewable Energy Sources in the UK

Biomass

Geothermal

Hydro

Solar photovoltaics(PV)

Solar thermal

Any fuel derived from organic matter, such as wood, oil crops, andagricultural & animal residues. Biomass can also be termed as biofuel,biodiesel, and biogas, and can be used for heat production, electricitygeneration and fuelling vehicles using a wide variety of conversiontechnologies. Biomass is renewable only when dedicated crops or forestsare used or where replanting occurs. The carbon absorbed during growthwill be equal to the emissions during combustion.

Traditionally, geothermal refers to thermal energy from the Earth’s core.Heat and electricity can be generated by circulating water deepunderground, where it is heated naturally by hot rocks. As an electricitygenerating option it is geographically specific, with good resources in partsof the US, and in Kenya and the Philippines. The term is increasingly used tocover near-ground energy stores, which can be exploited for low-level heatusing a ground source heat pump. This latter option has good potential inthe UK, although it does require an electrical input which (with the currentelectricity mix) will be only partially renewable.

Makes use of the energy from moving water, usually by channelling waterat high pressure from the top to the bottom of a dam or by making use ofriver flows to drive an electricity generator. The energy is obtained from thesun, which evaporates water from the sea and deposits it over land, givingit potential energy in the form of height. Although large-scale hydro usingdams is still being developed around the world, UK developments will focuson small-scale, ‘run of river’ projects due to their lower environmentalimpact and smaller spatial requirement.

Solar PV uses high-tech solar cells (usually made from silicon) to produceelectricity directly from sunlight. Although currently quite expensive, solar PVcosts have fallen dramatically over time and further falls and technologicalimprovements should be possible. Direct sunlight is not necessary and thecells can produce electricity even during cloudy conditions (at a reducedrate). Future applications for solar PV in the UK are likely to centre onbuilding integrated solutions, such as cladding and roofing.

Solar panels can be fitted to absorb heat from the Sun. This is usually usedto heat water, primarily for domestic purposes, although industrial andcommercial applications also exist. Solar thermal is exploited extensively incountries such as Cyprus and China, but so far has had limited penetrationin the UK. It is now being given more encouragement. A solar thermalcollector can provide around 60% of a household’s hot water requirementover the year in UK conditions.

Box 2



Renewable Energy Sources in the UK

Tidal

Wave

Wind

Despite very large resources, tidal energy has not been successfullyexploited on a wide scale. Tidal produced electricity is generated by makinguse of tidal water flows. It can be done by constructing a tidal barrage in anestuary and operating this like a conventional hydro dam – however, theenvironmental impacts are often prohibitive. Alternatively, turbines can beplaced underwater in the tidal stream – these produce power from both inand out flows. Other variations are also possible. Tidal power is gainingincreased interest in the UK, with a number of projects at demonstrationand testing stage.

Waves transmit large volumes of energy from windy conditions far out tosea to the shore. Here the energy can be used to generate electricity and avariety of technologies are being developed to do this. The potential ofwave energy in the UK is large due to our extensive coastline.

The subject of this report, wind energy is widely dispersed, although isgreatest in high latitude locations. Wind has been used for centuries inwindmills of various forms for grinding grain or pumping water. Modernwind turbines are available for both large and small scale electricitygeneration, and huge technological advances have been seen over the past20 years.

Box 2 (Continued)

Figure 4: Makeup of renewable electricitygeneration in 200315

2.5 UK wind resourcesThe UK has some of the best wind resources inEurope, if not the world, in both onshore andoffshore locations. This makes the British Isles avery attractive location for wind developments,as high average wind speeds and goodreliability results in more power output andlower costs. Figure 5 shows the onshoreEuropean wind resources whilst Figure 6 showsoffshore resources.

■ Wind and wave

■ Solar PV

■ Small scale hydro

■ Large scale hydro

■ Landfill gas

■ Sewage sludge digestion

■ Municipal solid waste combustion

■ Biomass co-firing

■ Other

12.08% 0.03%1.08%

29.23%

3.22%

30.76%

9.06%

5.65%8.89%

Onshore wind resourceWind energy resource studies commonly quote atop-level ‘theoretical’ resource which isprogressively reduced by including variousconstraints such as conservation areas, urbanconurbations, low wind speed areas, unsuitableterrain, etc. This leads to the so-called ‘technical’resource which is then further constrained byconsideration of planning, environmental and

social issues leading to an estimation of the‘practical’ resource. Table 2 gives some DTIpredictions on the theoretical and practicalonshore resource available in the UK10. Onlyabout 34,000 GWh is needed to reach the 10%target for 2010 from all renewables, so there ismore than enough onshore wind energyresource alone to achieve that.



Figure 5: European wind energy resources - onshore9



Table 2: Estimate of UK onshore wind energyresources10

A study entitled ‘Scotland’s Renewable Resource2001’ found that onshore wind energy inScotland is “widespread and is the cheapest ofthe renewable energy technologies considered”,with 11.5 GW of capacity identified as“available” at low cost11. The Scottish Executivecalculates that there is enough potential energyfrom onshore wind power alone to meetScotland’s peak winter demand for electricitytwice over.

1,000,000

Theoretical (GWh)

50,000

Practical (GWh)

Figure 6: European wind energy resources - offshore9



Offshore wind resourcesThe UK’s offshore wind energy resource issubstantial, estimated at around 100,000 GWhof practical resource12. The first phase of theGovernment’s bid to release offshore sites fordevelopment saw 18 sites awarded leases todevelop over 1,000 MW of capacity. The firstoffshore wind farms in the UK (North Hoyle,Scroby Sands and the Blyth Offshore pilotproject) currently contribute 124 MW of offshoregeneration. These are the first of 12 projectsthat were granted funding under Round One ofthe UK Offshore Wind Development programme,the aim of which is to demonstrate offshoretechnology in the UK and make it commerciallyviable.

The Department of Trade and Industry (DTI)developed a strategic framework for theoffshore wind and marine renewables industriesfollowing its ‘Future Offshore’ consultation inFebruary 200313. It then commissioned aStrategic Environmental Assessment (SEA) ofthree areas around the UK coast marked fordevelopment. Expressions of interest frompotential developers of new offshore wind sitesunder Round 2 led to the letting of sites for 15projects, with a possible combined capacity ofup to 7,200 MW. Many of these projects arecurrently proceeding to the EnvironmentalImpact Assessment (EIA) stage, and formalplanning applications for the most advancedprojects are expected to be submitted during2005-2006. Of the capacity already consented

from Round One, some 500 MW is expected tobe commissioned and generating by the end of2005.

2.6 Current and future windcapacityIt is widely expected, both by Government andindustry experts, that wind power will representthe majority of new renewables capacity in2010 and 2020. There is currently 888 MW ofwind energy connected to the grid in the UK,generating around 2,300 GWh of electricity peryear14. During 2005 a further 600 MW isexpected to be commissioned, with more in thepipeline – see Table 3.

Recent energy trends show that total electricitygeneration from renewables in 2003 (the mostrecent figures available) amounted to 10,600GWh. There was a 12.5% increase in theinstalled generating capacity of renewablesources in 2003, mainly as a result of a 39%increase in wind capacity15. However, themajority of renewables generation in 2003 camefrom large hydro, waste to energy, and biomassplants – see Figure 4.

Current predictions are that there will be around8 GW of wind capacity by 2010, made uproughly of 4 GW onshore and 4 GW offshore.

Onshore

Offshore

Total

764

124

888

600

180

780

1,100

810

1,910

Built (MW) Under Construction(MW)

Consented (MW)

Table 3: Wind capacity status as of January 200516


3 Wind power technology and network integration

Summary• The energy payback of wind farms has been estimated at 3-10 months

• Wind availability can be forecast to reasonable accuracy in the timeframe relevant to theelectricity market

• As the penetration of wind output increases, additional balancing services are required – this isa cost issue rather than a technical constraint

• When wind energy accounts for around 6% of total electricity generation, it displacesconventional plant at around 35% of installed capacity, falling to 20% displacement when wind output reaches 20%

• There is no technical limit to the amount of wind capacity that can be added to an electricitysystem – the only constraint is one of economics

3.1 Wind turbine technology

Advances in designWind energy is one of the most commerciallydeveloped and rapidly growing renewableenergy technologies in the UK and worldwide.The first UK wind project had ten 400 kWturbines in 1991; just 14 years later turbines often times that output are operating. This hasinvolved achievements in engineering design,aerodynamics, advanced materials, controlsystems and production engineering to growrotor diameters from 30m to 80m, towerheights from 40m to 100m, and power outputsfrom 200 kW up to 4 MW (4,000 kW).

Developments continue in many discretetechnological areas to ensure that future turbinesare more powerful, quieter, need lessmaintenance, capture more energy, are quicker tobuild and integrate better into grid operations. Asmore are built then both the economies of large-scale production and learning-curve effects shouldenable the wind energy industry, which is verycapital intensive, to deliver electricity at lowercost. Further technical details on the componentsand design of modern wind turbines are providedin Annex A.

Power outputWind turbines produce power over a wide rangeof wind speeds. They cut in at between 3 and 4m/s, reach their rated output at about 13 m/sand are regulated to produce their maximumoutput through to 25 m/s, when they typicallyshut down to protect the drive train, gearboxand structure from potential damage – seeFigure 7. This maximum speed is equal to 55mph, which is above gale force 9, defined aswhen tree branches break. In the UK windenvironment a wind turbine will be producinguseful power for 70-85% of the year, equatingto 6,000-7,500 hours per year.

Capacity factorThe term ‘capacity factor’ refers to the ratio ofactual electricity production over what couldhave been produced by a plant runningcontinuously at full capacity – for wind plant thecapacity factor is often quoted over a year. It issimilar to the term ‘load factor’, which is moreoften used when describing the operations ofconventional plant.

Wind turbines have a lower capacity factor thanconventional power plants because they will notbe producing electricity at full output for most ofthe time. Individual wind turbines situated in the



UK may have a capacity factor of 20-40%. Theexact figure is dependent on location, technology,size, turbine reliability, and the wind conditionsduring the period of measurement – the capacityfactor during the winter is therefore much higherthan in the summer. Capacity factors are likely tobe higher in the UK than in continental Europedue to our greater wind resources.

There is some disagreement over projectedaverage capacity factors for UK wind farms. Afigure of 30-35% is commonly used, but this hasbeen challenged based on the poor performanceduring 2002 (24.1%) and a number of otheryears, when wind conditions were lower thanaverage and quoted capacity factors wereparticularly low15.

This report explicitly uses the higher figure of35% in its cost calculations, in line with theassumptions taken by Dale et al17 in theirestimate of the ‘system cost’ of wind power, seeChapter 4. As their calculations (and a numberof others in this report) are based onassumptions for 2020, a higher capacity factor isjustifiable because capacity factors are expectedto rise over time due to the exploitation ofwindier sites (in Scotland and Northern Irelandespecially), increased offshore development(where wind conditions are more stable –capacity factors of 40% are expected13), andimproved technology and reliability. A lowercapacity factor of 30% is used in Chapter 2 ofthis report as this figure relates to 2010, bywhen less of an improvement can be expected.

Design lifeThe average design life of a wind turbine is about20 years. After this time, the turbine site could berefitted using the latest technology (often termedas ‘repowered’) or decommissioned; the latter issometimes a requirement of a planning decisionand a new planning application would berequired for refitting to occur. However

repowering is a very practical and economicoption and has already been done in the UK.

3.2 Energy balanceAlthough wind turbines do not producegreenhouse gas emissions when generatingelectricity, they are responsible for some‘embodied’ emissions resulting from the energyused in their manufacture. This is because thecurrent energy mix is primarily fossil fuel based.All electricity generating technologies, includingrenewables, will require energy duringmanufacture, construction and operation, so theenergy balance issue does not apply just towind power.

However, the energy balance, or ‘payback’, ofwind power is often mentioned as a factor thatlimits its effectiveness. There are a number ofstudies on this subject, although because of thewide variations in assumptions that can be used,care should be taken when comparing differentstudies. Most studies suggest that wind turbinestake between 3 to 10 months to produce theelectricity consumed during their life-cycle -from production and installation through tomaintenance, and finally decommissioning18. TheHouse of Lords Science & Technology SelectCommittee reported a figure of just over oneyear for onshore wind22. A more recent study bythe wind turbine manufacturer, Vestas,calculates life-cycle energy values for twooperational wind farms in Denmark (onshoreand offshore) using modern 2 MW machines19.The results put energy payback at just undereight months for onshore turbines, and ninemonths for offshore machines. The difference isdue to the greater amount of constructionmaterials (steel and concrete) needed offshoreand the need for more extensive gridconnections. If anything, these figures are likelyto be lower in the UK due to superior windresources over Denmark, leading to moreenergy production and a quicker payback period.



Figure 7: Typical wind turbine power curve illustrating electrical power generated at key wind speeds20

2500

2000

1500

Cut-in wind speed

Average wind speed

Rated wind speed

Storm protectionshut-down

1000

500

00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Wind speed (m/s)

Out

put,

kW

3.3 UK electricity supply systemThe UK’s electricity supply system is designed toensure that generation and demand arematched at all times. The system consists oflarge, centralised generating plants connecteddirectly to the high voltage transmission systemwhich spans the country. This connects tolocalised distribution networks, which deliverthe electricity to the end-user at a lower voltageusing a combination of overhead andunderground cables.

Great Britain’s (GB) electricity system is one ofthe world’s first fully liberalised electricitymarkets (see Box 3), with generating plants, thenational grid system, distribution network andsupply companies all privately-owned andoperated under the regulation of Ofgem (The

Office of Gas and Electricity Markets). Thenational grid is run by National Grid Company(NGC; wholly owned subsidiary of National GridTransco), who are responsible for ensuring thereliability and quality of electricity supply. Strictrules and targets are in place for them to followand any serious deviation can result in a heavyfine.



Box 3

The British Electricity Trading and Transmission Arrangements (BETTA) came into operation in April2005 to cover the whole GB electricity grid, replacing the New Electricity Trading Arrangements(NETA) that were introduced in March 2001 and covered just England & Wales. Under BETTA (andNETA before it), electricity is traded through bilateral contracts between generators, electricitysuppliers and customers across a series of markets operating on a rolling half-hourly basis. NationalGrid Company (NGC), the system operator of the GB electricity transmission system, operates abalancing mechanism to ensure system security at all times. Generators are out of balance if theycannot provide all the electricity they have been contracted to provide or if they have supplied toomuch. Suppliers and customers are out of balance if they have consumed too much or too little.Market experience and adjustments since the introduction of NETA have reduced price volatility in thebalancing mechanism such that the penalties for generators of less predictable sources of electricitysuch as wind power are relatively small.

BETTA (and NETA)

Although the majority of wholesale electricity istraded over long-term contracts betweengenerators and supply companies, NGC mustensure the real-time matching of supply anddemand.

The capacity of the GB electricity system iscurrently around 75.5 GW, with a peak winterdemand of 62.7 GW21. The minimum load in anaverage year is roughly 20 GW – this wouldnormally be experienced in the very early hoursof a warm summer morning.

The Northern Ireland electricity system is fullyconnected with the Republic of Ireland system,and has a 500 MW interconnector to Scotland.Total generating capacity in NI (including theinterconnector) is currently 2.15 GW, with a peakdemand of 1.67 GW.

3.4 Balancing the system

Variable demandThe demand for electricity, or load, changesthroughout the day and is dependent on a largenumber of factors, including the weather

(temperature, wind speed), daylight conditions,the time of day, and TV schedules. On a typicalwinter day the load increase can reach up to12,000 MW in two hours over the morning loadpickup period as shown in Figure 8. The systemalso has to deal with more sudden increases indemand, such as those seen during or after TVprogrammes. In 1990 the end of extra time inthe World Cup semi-final between England andGermany resulted in a demand surge of 2,800MW over a few minutes, the largest everrecorded for a TV programme.

Synchronised tea-makingIf the 25 million kettles estimated to exist inthe UK were used at once, the 75 GW demandwould be equal to the maximum installedcapacity on the grid. Any additional demand,from lighting or industry, would overload thesystem and lead it to fail. This illustrates howthe system is designed to rely on aggregatebehaviour rather than deal with every remotepossibility.



As well as coping with steep demand changesthe electricity system must also be able to dealwith sudden losses of supply. This could be afault at a large power station or the loss of amajor transmission line. The system is thereforedesigned to withstand the loss of the largestoperational unit, which currently equals 1,320MW of capacity (Sizewell B nuclear powerplant).

Quality of supplyThe electricity system has an inherent level ofinertia that is represented through changes infrequency, which is allowed to deviate from thetarget of 50 Hz by a small margin of 1%.Fluctuations in frequency are a direct measure ofthe balance between demand and generation inan AC power system and in order to maintain astable frequency, and therefore quality ofsupply, the system operator contracts for anumber of balancing services.

In the time horizon of less than a minute,frequency is controlled automatically throughfrequency response services, which arecontracted by the system operator. Frequencyresponse is primarily provided by large, centralgenerators (>100 MW) equipped withappropriate governing systems thatautomatically change active power output inresponse to a change in system frequency.

In addition, reserve is required for themanagement of system frequency after asudden and sustained loss of generation orincrease in demand, and is provided by bothgenerating plant and load reductions from some

industrial customers. If system frequency is toolow (ie. there is a shortage of generation tomeet demand), the operator can call uponallotted reserves, such as conventional plantrunning at reduced capacity (often called‘spinning reserve’vi) and storage facilities, suchas the two pumped storage plants in Walesvii.Load reduction, also a form of reserve, isachieved through demand management. Thisservice is provided by some large industrialcustomers, who are able to respond to a requestto reduce their demand, for which they receivea payment.

In summary, the system operator needs tomanage both predictable variations in demand(such as managing morning load pickup) butalso deal with unpredictable events such asoutages of generators and errors in demandforecasts. Such losses of supply can amount toover 1,000 MW in less than a few seconds, butthe system is capable of dealing with thisthrough the use of balancing services, asdescribed above.

vi Spinning reserve is the term used to describe conventional plant which is purposely operated at lower than maximumoutput in order to provide a quick increase in output at the request of the system operator. Plant operated as spinningreserve is less efficient than when at maximum output, and the generator will usually receive a payment for this service.

vii Pumped storage plants use cheap electricity in off-peak periods to pump water from a lower to a higher reservoir. Theycan then be called upon during peak periods to release this water back down, providing response output in around 10seconds. They are a relatively efficient way to provide rapid reserve response.



Figure 8: Typical winter demand, Tuesday 3rd December 200221

0:00

0:34

1:09

1:43

2:18

2:52

3:27

4:01

4:36

5:10

5:45

6:19

6:54

7:28

8:03

8:37

9:12

9:46

10:2

110

:55

11:3

012

:04

12:3

913

:13

13:4

814

:22

14:5

715

:31

16:0

616

:40

17:1

517

:49

18:2

418

:58

19:3

320

:07

20:4

221

:16

21:5

122

:25

23:0

023

:34

Out

put,

GW

0

10

20

30

40

50

60

Nuclear CCGTs Imports Large Coal Other Coal Oil Pumped Storage Other

Time

3.5 Capacity and flexibility ofwind power

The need for reservesIt is commonly assumed that adding significantwind power capacity to the electricity systemwill lead to a large expansion in the need forbalancing services, particularly reserves. This isdue to an implicit assumption that theintermittent output of wind power results in theneed for large amounts of reserves devotedentirely to providing standby power for windoutput – this is often referred to as ‘backupplant’. Therefore, if the average output of windplant is 35% of its rated output (its capacityfactor), the remaining 65% must be provided asreserve, or backup capacity.

This reasoning is seriously flawed, for three keyreasons:

• No generating plant is 100% reliable.Therefore, reserves are required to cover forunexpected outages on all plants.

• The rated capacity of the total installed windplant is of minor interest to system operators,who make supply security assessments basedon estimates of overall statistical probabilitiesfor the complete generating mix. This leads tothe concept of ‘capacity values’, describedbelow.

• Wind power is often described as‘intermittent’, which implies a high leveluncertainty as to its actual output, but it canbe quite accurately forecast in the appropriatetimeframes for balancing electricity supply. A



more precise term might be ‘variable’,especially when considering aggregate output,which benefits from the wide distribution ofwind turbines across the country.

Instead, system operators assign all generatingplant a ‘capacity value’ (often called ‘capacitycredit’), which refers to the ability of that plantto contribute firm capacity to the overall system.High availability plant such as combined cyclegas turbine (CCGT) can have a capacity value ofup to 90%, meaning 10 GW of gas plant wouldbe treated as providing the system with 9 GW offirm capacity – the remaining 1 GW allows foroutages, both scheduled and unscheduled.Existing nuclear plant in the UK has recentlyshown lower capacity values of 75%, due to anumber of problems at individual plants.

No plant has a capacity value of 100%, becausethere will always be some statistical probabilitythat it will not be available when required.When determining reserve requirements, systemoperators make an assessment of the needs ofthe system as a statistical whole rather thanconsidering the needs of each individual plant.This leads to a treatment of wind output that isdifferent than if it were the only generatingsource available.

Capacity value of windDue to the variability of wind power, its capacityvalue is more limited, as it will not be possibleto displace conventional generation capacity ona ‘megawatt for megawatt’ basis. The capacityvalue decreases as more wind is installed on thesystem; at low penetrations it has been put atroughly equal to the capacity factor for wind(30-35%), but at higher penetrations the valuedecreases. This is because with low penetrationswind output is hardly noticed on the system, butwhen this increases, the variability of windbecomes more noticeable and its ability toprovide firm capacity is reduced. National Grid

Company have stated that 8,000 MW of windcapacity would displace 3,000 MW ofconventional plant, with 25,000 MW displacingthe need for 5,000 MW. This means that windpower has a capacity value of around 35% atpenetrations of around 6%, declining to around20% at penetrations of 20%. These figures,along with other corroborating evidence, wereaccepted by the House of Lords Science &Technology Select Committee in their 2004report into renewable energy22.

It is worth noting that the capacity value ofwind is higher in the winter than in thesummer, in line with seasonal changes in thecapacity factor. This means there is a correlationbetween the capacity value and times of peakdemand.

Lower capacity values have been reported inother countries. For example, a recent report byE.on Netz, one of Germany’s network operators,with 44% of that country’s wind capacity, quotesan average yearly capacity factor of just over15%23. However the UK’s greater resourcemeans that capacity factors and the associatedcapacity values tend to be higher than mostother European countries and comparisons cantherefore be difficult. In addition, the integratednature of the GB electricity grid, differing tradingrules (eg. gate closure times), and its widegeographical distribution, separates it fromsome of the other problems faced in Germany.

Wind forecasting and distributionWind conditions may not be that easy to predictover the course of days or weeks, butforecasting for the next few hours has becomequite accurate. Figure 9 illustrates this byshowing a typical 1-hour wind forecast againstactual output for one wind farm over a period ofa week. The total output of all wind capacitywill be less variable, as it will be made up of alarge number of wind farms spread throughout



the country. It therefore follows that greatergeographic diversity in wind farm locations isbeneficial to the combined output profile ofwind power.

The GB electricity supply market operates with aone hour ‘gate closure’, meaning that contractsto supply electricity have to be agreed one hourin advance. By this time the system operatorand other market participants will have a goodidea of the likely contribution of wind powerwithin the overall system, and other plant willbe scheduled accordingly. Any shortfall inpredicted wind output will then be met by theroutine use of balancing services.

The accuracy of wind forecasting will continue toimprove as more sites are developed andforecasting models are refined.

Accommodating wind powerIt should now be clear that accommodatingsignificant amounts of wind capacity on theelectricity system is not likely to pose any majoroperational challenges, and this view has beenconfirmed by the GB system operator, NationalGrid Company. It is also the conclusion of acomprehensive report on this issuecommissioned by the Carbon Trust and DTI25. Athigher wind penetrations, the capacity value ofwind is indeed reduced, and this does lead toadditional balancing requirements. However, thisrepresents a cost rather than a barrier, asadditional reserve requirements will lead to anincrease in systems costs – this is explainedfurther in Chapter 4.

On an operational level, wind power has onedistinct advantage when compared to largecentralised plant. Faults at conventional plantcan cause a large instantaneous loss of supply

Figure 9: Wind farm forecast (+ 1 hour) Vs actual output, Ireland 2004 (data provided by Garrad Hassan)24

0

10

20

30

40

50

60

70

80

90

100

1 May 2004 3 May 2004 4 May 2004 5 May 2004 6 May 2004 7 May 20042 May 2004

Date

Pow

er (

% o

f ca

paci

ty)

Actual Forecast



that must be dealt with using a full range ofbalancing services. In contrast, combined windoutput does not drop from the system in thesame way, even under extreme weatherconditions (too much, or no wind). Variations inwind output are smoother, making it easier forthe system operator to manage changes insupply as they appear within the overall system.

There is often some confusion between theadditional reserve capacity needed for wind andthe ‘plant margin’ – the extra capacity that anyelectricity system needs, over and above thelikely peak demand. It is sometimes impliedthat an extra plant margin is needed to providethe additional reserve capacity to cover forwind, but this is also misleading. Analysis of theeffect of integrating 20% wind output showsthat although the apparent plant margin ishigher, this is simply because the capacity factorof wind plant is lower. In reality, someconventional plant will have been displaced(because of the capacity value of wind),meaning the higher plant margin consists solelyof wind plant, because of its lower capacityfactor. The additional reserve capacity requiredto integrate wind energy will therefore beprovided by the remaining thermal plant. Thisissue is explained in more detail in Annex B.

Future reserve optionsAs already stated, the additional reserverequirements related to the variability of windcould be provided by increasing the use ofstorage and more emphasis on demandmanagement. These are further explained below:

• Demand management: There is scope for aconsiderable expansion in demand managementservices, with the possibility of domestic andcommercial appliances such as refrigeratorsbeing able (with the appropriate technologyinstalled in them) to respond to a drop infrequency by temporarily switching themselvesoff, without damaging the food inside.

• Storage: In the longer term there is thepossibility of much greater use of storage,although at present this is seen as anexpensive solution. The UK already has severalpumped storage plants, but future storagesolutions could rely on developing new large-scale ‘battery’ technologies, or compressed airenergy storage.

These options may become more attractive asthe percentage of intermittent renewables onthe national grid increases and as technologiesimprove. A large increase in electricity priceswould also provide a big incentive, particularlyfor storage. They both offer low or lower-carbonalternatives to increased use of reserves (which,as shown below, may come from inefficientplant), although in reality all available optionswill be utilised to some degree.

3.6 Displacement of fuel use andemissionsAs nuclear plant currently provides the primarybase load of electricity supply, wind generation islikely to displace coal and gas-fired plant This isillustrated well by Figure 8, which shows how coalgeneration is the primary load-following(marginal) plant. It is therefore reasonable toassume that wind power output will mainlydisplace coal, at least in the short to mediumterm. In the longer term, with greater reliance ongas-fired plant, significant wind penetration, andany increase in the price of gas relative to coal,wind may also begin to displace gas, but this willdepend heavily on the actual fuel mix in thefuture and the extent of demand managementand storage options.

It should be noted that the plant displaced bywind, and the plant needed to meet additionalreserve requirements are not necessarily thesame types of plant. Plant used to provideadditional reserve requirements might be thesame type as displaced plant, but not necessarily.



As discussed, some additional reserve may berequired by the system operator when windpower penetration becomes significant. Runningplants at reduced output is less efficient and soa small amount of additional fuel is used for thispurpose. However, the additional fuelrequirement will be far less than the totalamount of fuel displaced by the wind generatedelectricity. When wind produces 20% of totaloutput, it is estimated that the emissionssavings from wind will be reduced by a littleover 1%, meaning that 99% of the emissionsfrom the displaced fuel will be saved17.

3.7 Limits on wind capacityThe capacity of an electricity system to absorbwind generation is determined more byeconomics than by absolute technical orpractical constraints. As the percentage of windgenerating capacity rises, so do the technicaland network reinforcement issues that willrequire resolution. All of these are to somedegree influenced by the technologies availableat the time, and future technological innovationsmake the determination of long-term absolutelimits unreliable – for example electricity storagedevelopments could make higher windpenetrations possible.

The most obvious practical constraint on windcapacity occurs when peak wind output exceedsthe lowest period of demand on the grid system(ie. a windy summer night), allowing for therequirement for some base load plant tocontinue operating. At this point excess windcapacity will need to be curtailed, and this hasan economic cost for wind plant. Technicalconstraints include the ability of wind plant torespond to system faults, and this is related bothto the type of wind turbine technology used andto the dispersal of wind generation on the

network. Improvements in turbine technologyand network reinforcement are both possiblesolutions, again with possible cost implications.

It is generally considered that up to 20% windcapacity penetration is possible on a largeelectricity network without posing any serioustechnical or practical problems. Indeed, there isno absolute technical limit to UK wind capacity –instead the issue is an economic one, withhigher penetrations leading to increased unitcosts. The following statement from NationalGrid Company confirms this:

“We believe that, if there is a limit tothe amount of wind that can beaccommodated, that limit is likely tobe determined by economic/marketconsiderations.” 66

Much larger percentages are certainly possible –up to 100% if large-scale storage and greaterinterconnector capacity is available, possiblycombined with wind plant curtailmentviii – butthe additional cost would substantially increase.In parts of the UK, high local rates of windpenetration will require substantial investmentin network upgrades, and economicconsiderations may currently limit the ability ofthe local grid to absorb wind capacity.

FURTHER INFORMATION

“Renewables Network Impacts Study” –Carbon Trust / DTI -http://www.carbontrust.org.uk/carbontrust/about/publications/Renewables NetworkImpact Study Final.pdf

viii Curtailment would occur when the combined output from wind plant exceeds the load on the system; this is only likelywhen there is a high penetration of wind power on the system and high winds coincide with a period of low demand.


4 Costs and benefits of wind

Summary• The generation costs of onshore wind power are around 3.2p/kWh, with offshore at around

5.5p/kWh – this compares to a wholesale price for electricity of around 3.0p/kWh

• The estimated net additional cost (the ‘system cost’) of providing 20% of total output fromwind energy in 2020 is 0.17p/kWh based on current gas prices

• If the social cost of carbon is included, the net additional cost of wind power is reduced, andcould be zero

4.1 BackgroundIncreasing the use of wind power, andrenewables in general, will add some additionalcosts to the overall cost of electricity. This isbecause at present wind power is not thecheapest form of power generation, and thereare a number of additional system costs thatneed to be accounted for – for example,balancing and network reinforcement, asdescribed in the previous chapter. Higher costsfor carbon-free electricity generation are notlimited to renewables; most commentatorsagree that reducing CO2 through the greater useof nuclear power or carbon sequestration andstorage would also be more costly than newgas-fired plant and would also require someform of public support. The question then iswhether the cost of increasing renewableelectricity generation is acceptable within thecontext of the Government’s stated energypolicy, and its ultimate goal – to reduceemissions of CO2. To prepare the UK for thetough challenges ahead, the Government hasaccepted the need to stimulate investment inenvironmentally sustainable technologies thatare more expensive now, if they have thepotential to become competitive over time.Public support mechanisms for renewables arean example of this policy, and should beconsidered in this context.

There are some variations in differentcalculations of the costs of meeting therenewable energy targets primarily through

wind power. Many of the estimates of the costof wind power differ in their basic assumptions,making any comparison very difficult. There isalso confusion over what costs are beingpresented – the unit cost of wind power at thepoint of delivery, the cost to the system whichmust incorporate wind power, or simply the costto the consumer and taxpayer who has to payfor it.

This chapter will explain the background to windgeneration costs, before looking at system costsand the cost of public support for renewables.This is followed by an analysis of thealternatives to wind power and how these canbe expected to fit in to future electricity supply.

Further details on the components of windpower costs are included in Annex B.

4.2 Calculating generation costs Attention tends to be focussed on the‘generation costs’ of renewable technologies forcomparison with those of the conventionalsources of generation. Generation costs, for alltechnologies, depend on two sets ofparameters:

Technology specific• The installed cost of the plant, including

interest during construction

• Operation and maintenance costs



• Fuel costs – zero for wind, wave and solar,positive for coal, gas, nuclear and energycrops, negative for ‘energy from waste’

• The efficiency of the plant, in the case ofthermal sources of generation and the energyproductivity, in the case of wind, wave andsolar. The latter is normally expressed interms of kWh/kW of capacity, or a ‘capacityfactor’, which is simply the ratio of theaverage power to the rated power.

Financial• Cost of capital, or test discount rate

• Capital repayment period

These financial parameters determine the‘capital cost’ element of generation costs. Asmost renewable technologies are capitalintensive they are more sensitive to changes inthese parameters, as illustrated in Table 4ix. Witha 5% discount rate, wind appears to be only0.3p/kWh more expensive than gas, but with a10% discount rate, the gap widens to 0.9p/kWh.

Usually, private sector investments will use ahigher discount rate than those commissionedby the public sector and this makes financingparameters heavily dependent on nationalinstitutional frameworks. In Denmark, forexample, the utilities generally use public sectorparameters – typically interest rates of 5%, withcapital repaid over the life of the plant. In theUnited States, however, there are no fixedcriteria; discount rates are mostly in the range 8-10%, with capital repaid over periods ofbetween 15 and 20 years. As the UK’s energyindustry is fully liberalised, higher rates maywell apply.

Table 4: The effect of the discount rate ongeneration costs26

The technology specific parameters are, broadlyspeaking, independent of the location of theplant, although, in the case of wind, there aresignificant differences between wind speeds –and wind energy productivity – in differentgeographical locations. Figure 10 shows theeffect of different wind speeds on thegeneration cost of wind power using twoindicative installation costs (high and lowestimates) for both onshore and offshoredevelopments. As can be seen, a 1 m/s increasein wind speed can reduce generation costs byaround 25%.

There is an additional factor, however, that canmask the underlying costs of renewable energytechnologies. As most are not yet competitivewith the conventional sources of generation,various types of support mechanism haveevolved. These mechanisms may or may notpromote ‘cost reflectivity’ – ie. they may notaccurately reflect the true cost of therenewables they are supporting. TheRenewables Obligation is the Government’scurrent support mechanism, and the public costof this is likely to be higher than the renewablegeneration it is supporting, making it a poorguide to the real cost of those renewables. Thispoint is discussed in more detail later.

CCGT (gas)

Wind

Plant

5

10

5

10

Test discountrate, %

2.1

2.3

2.4

3.2

Gencostp/kWh

ix The absolute values for CCGT may now be out of date, due to changes in the price of gas since the report was prepared.



4.3 Wind power generation costsPresent-day wind power generation costs needto be calculated, as the Renewables Obligationmasks them. However, its predecessor, the Non-Fossil Fuel Obligation, did offer 15-yearcontracts, so data from the final bidding roundsis a good guide27. (No allowance has been madefor inflation, nor for the steadily reducing costsof the plant; although these two influences willcancel out to some degree). Table 5 includesdata from 3 sources considered to use eitherrobust analysis and/or real data, in order ofpublication date:

• Oxera28: An analysis carried out for the DTI

• WPM: A recent analysis which examined costdata from over 3,300 MW of wind around theworld29. Two figures are quoted; for “high”and “low” installed costs.

• IEA30: Recent data from Denmark, which has awealth of wind energy experience

There is a reasonable degree of consistencybetween these estimates. The Danish estimatesare lowest, in each case, reflecting the use of alow discount rate and long repayment period.Excluding these, the average generation cost fromonshore wind in the UK appears to be around3.2p/kWh (+/-0.3p/kWh), and the generationcosts from offshore wind are around 5.5p/kWh.

These prices may be compared with the latestestimates for the wholesale electricity price inthe UK market. The average for 2005 is likely tobe around 3.0p/kWh31. This has risen over thepast year, simply because the price of gas hasincreased, and it tends to reflect the price ofbaseload generation from gas-fired plant.

Figure 10: The effect of wind speed on the generation cost of wind power

0

1

2

3

4

5

6

7

8

6 6.25 6.5 6.75 7 7.25 7.5 7.75 8 8.25 8.5 8.75 9 9.25 9.5 9.75

Site mean wind speed at hub height, m/s

Gen

erat

ion

cost

, p/k

Wh

Offshore £1250/kWOnshore £800/kW

Offshore £1000/kWOnshore £560/kW



Table 5: Summary of wind generation costs

n.q. Not Quoted

Source

Onshore

Capitalcost, £/kW

O&M, £kW CapacityFactor, %

Tdr%

Life Gencost,p/kWh

Comments

NFFO5

Oxera

WPM

IEA/DK

-

605-800

800

550

585

-

15

n.q.

n.q.

16

-

30

36

27

27

8x

?

6

6

5

15

20

15

15

20

2.9

3.1

3.3

3.0

2.65

Average price

‘High’ cost, 8.5 m/s site

‘Low’ cost, 7.2 m/s site

Offshore

Oxera

WPM

IEA/DK

1100-1430

1200

970

1130

35-42

n.q.

n.q.

36

35

38

31

27

n.q.

6

6

5

20

15

15

20

5.5

5.7

4.9

3.2

‘High’ cost, 8.8 m/s site

‘Low’ cost, 7.8 m/s site

Of course, the generation cost of wind farmsdepends to a large degree on the wind speedavailable. As this is site specific, costs will varyto some degree, as shown in Figure 10. Thegeneration cost of onshore wind power will tendto face upward pressure as the best sites aredeveloped, although this has to be balancedagainst improvements in size and design –leading to projections that actual costs willcontinue to fall (see Section 4.8 below). Threerecent studies (ETSU32; ETSU33; DTI34) on thesubject project only modest upward pressure oncosts for the scale of onshore capacity needed tomeet current targets.

4.4 Comparing wind energy toconventional generation costsAlthough generation costs are used to comparerenewable energy and fossil generation, thatprocess is a ‘first order’ comparison, and is not

precise. A ‘level playing field’ comparisondemands that allowances are made for variousfactors, some of which add value to renewables,while some subtract.

The key issues are:

• External costs are costs attributable to anactivity that are not borne by the partyinvolved in that activity. All electricity-generating technologies come with externalcosts, and those from fossil fuel sources ofgeneration are due to the pollution whicharises from their use, and from the impacts ofglobal warming due to their CO2 emissions.Many economists argue that these costsshould be added to the generating costs, andthis is the thinking behind proposals forcarbon taxation. However, fully internalisedcarbon taxes could add unacceptable increasesto the price of electricity and so most

x Although developers set their own criteria, the electricity regulator used this rate to test commercial viability



governments give renewable energy sources afinancial boost instead, in the form of supportmechanisms. The advent of the EU EmissionsTrading Scheme will increase the price of fossilgeneration, but only by modest amounts – atleast initially.

• Embedded generation benefitsacknowledge that many renewable energysources are small-scale and so connect intolow voltage distribution networks. This meansthat losses in the electricity network may bereduced and, possibly, transmission and/ordistribution network reinforcements delayedor deferred. The calculation of these benefitsis a complex issue and they vary bothregionally and locally. However, these benefitsmay turn to costs if concentrations ofrenewable energy in remote regions triggernetwork reinforcements, as is happening inScotland. In reality, some parts of the UK willexperience embedded generation benefits,whilst others will face some network costs –the net effect of these will be passed on to allconsumers, regardless of location.

• Net additional system costs for variablegeneration apply especially to wind and waveenergy as explained in Chapter 3, and theseare discussed below.

4.5 System costs from wind energyOf great interest to governments and electricityconsumers is the likely additional cost, in total,of adding specified amounts of renewableenergy to an electricity network. The extra coststhat the electricity system might face, termedthe ‘system cost’, depends on:

• All the estimated costs of wind power(increased need for balancing services, higherinstalled cost, and network upgrades)

minus

• The estimated benefits (reduced conventionalfuel use, displaced costs of conventional plant– ‘capacity savings’).

The result is then a figure for the net additionalcost of electricity from the whole system when acertain percentage of wind generation is added.This will be made up from a number of differentcosts and benefits falling on different marketparticipants, and therefore estimates of thesystem cost concentrate on the net overall effect,which will most likely be passed on to consumers.

A number of studies have recently appearedwhich set out to quantify this net additionalcost. These are summarised in Table 6. Care

Reference Amount ofWind, %

Relevantdate

Extra cost,p/kWh

Comments

Dale et al35 (UK)

Black and Veatch Corp36.(Pennsylvania)

IWEA37 (Ireland)

German Energy Agency38

20

10*

41

From 5 to 15

2020

2015

2020

2015

0.30

0.02

-0.20

0.24-0.30

Changes in gas prices meanestimate now out of date; see boxand text

*Includes all renewables; windaccounts for 64% of these

Network costs assumed small;assumes 2% p.a. gas price rise

Wind speeds in Germany arelower than in UK, so morecapacity needed.

Table 6: Summary of recent analyses of net additional cost of wind power



should be taken when making directcomparisons, as the underlying assumptionsdiffer.

The principal conclusion to be drawn from theseresults is that the extra system costs associatedwith accommodating significant amounts ofwind energy into an electricity network are verymodest. It should be noted that the results fromthe first study have been superseded by recentchanges in the price of natural gas and thispoint is discussed below. It may also be notedthat, despite the lower wind speeds available in

Germany, the additional costs of accommodatingan extra 10% of wind energy are also modest.

Box 4 summarises the UK study by Dale et al., arigorous exercise done using National Gridexpertise and data. It evaluated the netadditional cost of wind power by assuming itmakes up 20% of total UK electricity output by2020. This percentage is used to provide anextreme scenario, where wind power producesall of the Government’s 2020 renewables target;in reality, this is unlikely to be the case, althoughwind is likely to be the largest contributor.

Box 4: Summary of study by Dale et al.17 – original results

Assumptions:Electricity demand grows by 17% to 400,000 GWh; peak demand = 70 GW; 26 GW wind capacitydisplacing 5 GW conventional capacity (capacity credit of 20%); average wind capacity factor of 35%= 20% of sales; 60% of offshore wind directly connected to network; risk of supply interruption innine winters per century (current standard); 8% discount rate; 15 year life for generating plant.

Cost assumptions in 2020:Generation plant costs for CCGT : £400/kW, operation costs £20/kW, load factor 85%;Fuel cost 1.3p/kWh; Generation plant costs for wind: £455kW onshore, £600kW offshore; operation costs £11/kWh/yronshore, £20kWh/yr; capacity factor 35%; Cost of balancing without any wind: £345M/yr Extra balancing costs for wind : £2.85/MWh of windTransmission infrastructure costs: £100/kW or £1.7bn-£3.3bnxi;Wind connection costs: £50/kW or £0.6bn-£1bn;Transmission connection costs avoided (conventional) – credit of £0 - £300m;Distribution network reinforcement costs: £40/kW, or £420m.

Total extra cost:0.3p/kWh sold (or 1.6p/kWh of wind produced) = 5% increase on current average domesticconsumer electricity price (6.0p/kWh).

Extra cost in 2020 of electricity to the consumer if 20% of electricity is sourced from wind,compared to a coal/gas mix

xi These transmission and connection costs are based on the application of NGC’s deterministic investment standards, whichassume a wind power contribution on-peak of 60%. This assumption was challenged by Ofgem in their review oftransmission network charges in 2004, and NGC are now researching a new approach. However, as transmission costsrepresent only a small percentage of additional system costs from wind power (see Figure 12), any upward revision islikely to have only a small effect on the final figure.



Updated analysisAs the price of gas goes up, so the ‘fuel savingvalue’ of wind energy also goes up and the netadditional cost goes down. The original analysis,above, implicitly used a UK delivered gas price(the ‘beach price’) of about 19p/therm. Onerecent analysis suggests 30p/therm is nowmore appropriate for long-term contracts, atleast until 2005/639. Other estimates go higher.Prices on the US futures markets for gasdelivered in 2007 equate to nearer 40p/therm.As it is extremely difficult to quote future gasprices with any certainty, a range of gas priceshas been used.

Figure 11 updates the earlier analysis, showingestimates of the extra cost to the electricityconsumer of 20% wind energy, for a range ofUK gas prices.

It is also instructive to estimate the extra costswith lesser amounts of wind. Department ofTrade and Industry (DTI) and British Wind EnergyAssociation (BWEA) modelling suggests thatwind might supply 75% of the 2010 target of10% renewable generation. By 2010, windprices will not have fallen as far as 2020projections, and so appropriate assumptionshave been made.

The graph shows that the extra cost to theelectricity consumer of 7.5% wind by 2010would be about 0.12p/kWh (with gas at19p/therm, as in the original analysis). Withhigher gas prices it would be less: 0.06p/kWhwith gas at 30p/therm, or 0.009p/kWh with gasat 40p/therm.

Figure 11: Estimates of the extra cost to the electricity consumer of wind energy, for a range of gasprices40

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

19 25 30 35 40

UK gas price (p/therm)

Net

add

itio

nal s

yste

m c

ost

of w

ind

(p/k

Wh)

20% wind 7.5% wind



Similarly, 20% wind by 2020 would add about0.17p/kWh to electricity prices, with gas at30p/therm (today’s prices), or 0.03p/kWh withgas at 40p/therm. This compares with a netaddition of 0.32p/kWh with gas at the originalprice of 19p/therm.

Figure 12 shows how the 20% wind powerscenario compares to the conventional(gas/coal) scenario by breaking down the costcomponents used in the analysis. This illustrateshow additional balancing and infrastructurecosts are only a small part of the net additionalcost of incorporating 20% wind power.

Further qualificationsIt should be noted that the net additionalsystem cost of wind energy derived from thisanalysis might be slightly pessimistic, for threereasons:

• No allowance is made for the ‘cost of carbon’under the EU Emissions Trading Scheme, sinceit is difficult, while the scheme is in itsinfancy, to estimate an overall incremental

price for gas generation. This issue is dealtwith below.

• It is argued by some that the price of gasshould be adjusted for ‘market risk’.Generation costs for a gas-fired plant mayincrease during its life, due to increases in theprice of gas. Several studies have attemptedto quantify this risk by ‘loading’ the price ofgas, and the additional generation cost is ofthe order 1p/kWh41. It should be noted thatthere is no comparable price uncertaintyassociated with wind energy generation costsas, once the plant is built, generation costsare more or less determined – apart fromunforeseen charges in interest rates, whichwould affect all generators to some extent.

• The model used by Dale et al reflects ‘reallife’, in as much as the introduction of new,high load factor plant will depress the loadfactor of all the existing plant as discussed inAnnex B. This results in a small increase in thegeneration costs of the existing plant. Theaddition of new nuclear, rather than wind,plant to the portfolio would push up

Figure 12: Breakdown of the cost of electricity generation under conventional and 20% wind powerscenarios (with gas at 30p/therm)

■ Transmission infrastructure upgrades

■ Onshore connection

■ Offshore transmission & connection

■ Onshore wind capital + O&M

■ Offshore wind capital + O&M

■ Balancing services

■ Fuel

Conventionalscenario

20% wind power scenario

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

pen

ce/

kWh



generation costs by about 0.05p/kWh. Whilstlarge amounts of new wind energy wouldpush up costs by more than this amount, a‘level playing field’ demands that 0.05p/kWhshould be deducted from the net additionalsystem costs identified above.

Calculating carbon benefitsAs CO2 is harmful to the global climate, the costsof climate change can and should be attributedto emissions resulting from human activity. It isthis principle that is behind calls for carbontaxation, and efforts to create a market foravoided carbon in the form of the EU EmissionsTrading Scheme – so that a price is attached toCO2 emissions.

In 2003 the Government published itsassessment of the ‘social cost of carbon’42 tohelp give a value to carbon emissions in theabsence of full-scale carbon taxation, for whenpolicies are being developed. The value agreedon by Government was a range of £35-140 pertonne of carbon (tC), with a middle value of£70/tC. This translates to £9.55-38 per tonne ofCO2 (tCO2), with a middle value of around£19/tCO2. However, the Government alsoacknowledged that such estimates are hugelyvaried and that such large-scale harm is difficultand controversial to measure accurately. Arevised analysis is expected in the near future.

The social cost of carbon is very different fromthe market price of carbon, which is operating inthe EU Emissions Trading Scheme. The marketprice in the EUETS is dependent on the allocationof permits by EU Governments and theperformance of companies in the scheme, but iscurrently trading at around £10/tCO2 and istherefore at the lower end of the Government’srange for the social cost of carbon.

As wind energy is a CO2-free energy source thatmust compete against fossil fuel alternatives, it

seems reasonable to try and account for the‘social cost’ from CO2 emitted by conventionalpower generators and subtract this from thesystem cost of wind. This is particularly relevantwhen the system cost calculations above do nottake account of the market price of carbonstemming from the EUETS.

To do this one must make some assumptions asto how much carbon wind energy output isdisplacing. There are large differences betweenthe CO2 emissions associated with coal (243tC/GWh) compared to natural gas (97 tC/GWh),with none associated to nuclear power. Asalready explained, it would be unrealistic toassume that wind energy would displace anynuclear capacity, and it is most likely that it willdisplace coal in the short to medium term.However, the actual CO2 displacement in 2020 ishard to estimate and so for the purpose of thisreport, it has been assumed that wind outputwill displace the average emissions resultingfrom gas-fired plant. This figure is likely to beconservative, as in reality some coal-firedgeneration is likely to exist in 2020. However, itis the figure that the DTI use and is used here so

Carbon Vs CO2

Carbon emissions are often quoted in twoways: in tonnes of carbon dioxide (tCO2) andin tonnes of carbon (tC). A tonne of CO2

contains less carbon than a tonne of carbondue to its chemical composition. Theconversion formula is:

1 tCO2 = 0.273 tCor1 tC = 3.66 tCO2

Therefore, when converting carbon values thesame formula must be used:

Eg. £1 /tCO2 = £3.66 /tC



that the carbon benefits of wind power are notoverestimated.

Using this figure, and assuming wind energymakes up 20% of total output in 2020 (assumedto be 400,000 GWh – following previousanalysis), the CO2 emissions savings of windoutput can be estimated at 28.4 million tonnesof CO2 per year (or 7.8 MtC). With this figure it isthen possible to attach a value to this saving

based on the range of estimates for the socialcost of carbon – see Table 7.

If these values are then subtracted from the netadditional system costs due to wind energy, thisgives a more realistic picture of the net socialcost of incorporating wind energy onto theelectricity system. Figure 13 summarises theresults.

Social cost of carbon Total social value of CO2 saving Social value of CO2 saving per unitof electricity

£9.50 /tCO2 (minimum)

£19 /tCO2 (mid-range)

£38 /tCO2 (maximum)

£271m

£540m

£1079m

0.068p/kWh

0.135p/kWh

0.270p/kWh

Table 7: Impact of the social cost of carbon on the net system cost of wind energy

Figure 13: Effect of including the social cost of carbon into estimates for the net system cost of windenergy at 20% of total output

£9.55/tCO2 £19/tCO2 £38/tCO2

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

19 25 30 35 40

Gas price

Net

add

itio

nal s

yste

m c

ost

of w

ind

(p/k

Wh)



As this chart shows, accounting for the socialcost of carbon reduces the system cost of windpower, making it positive when a high cost ofcarbon is assumed. Therefore, the social benefitof having 20% wind output might outweigh anycosts. Of course, these benefits will not bereflected in the cost of electricity until carbonvalues are sufficiently internalised in the price offossil fuels.

4.6 Cost of UK supportmechanismsThe primary support mechanism for renewablesin the UK is the Renewables Obligation (RO),which was described in Chapter 2. The ROcreates a market demand for renewableelectricity generation and does not require aGovernment subsidy – the cost is passed on tothe consumer rather than the taxpayer. The ROwill primarily assist commercially advancedrenewables such as wind, biomass and methanerecovery as these lower risk technologies will bemost favoured by investors. To support othertechnologies at the development or pre-commercial stage the DTI funds a number ofresearch & development and capital grantprogrammes to stimulate investment andinnovation.

A recent report by the National Audit Office(NAO)43 expects total public support for allrenewables to reach around £700m per annumbetween 2003 and 2006, two thirds of whichwill come from the Renewables Obligation,which is paid by consumers through theirelectricity bills. The remaining third is paid bytaxpayers in the form of the DTI’s capital grantsxii

and innovation programmes, and through taxexemptions. The total cost of the RO is expected

to equal around £1bn per annum by 2010, equalto an increase of 5.7% in customers’ bills42.Although large, this figure is believed to bemuch less than the historical subsidies given toconventional fossil fuel technologies over thepast 60 years, and it avoids the significant‘social cost’ that comes with air pollution andcarbon dioxide emissions. It also helps createfuture options to the climate change problem,which although more expensive now maybecome competitive over time.

It is important to note that the NAO estimatesdo not correspond to the net additional systemcosts of wind, as detailed above. The reasons forthis are:

• As the NAO points out, the cost of the RO is toa large extent unaffected by the cost of thetechnologies it is supporting. It is thereforenot ‘cost reflective’.

• The DTI assessment of the impact of the RO(to which the NAO report refers) does notinclude network reinforcement costs.

• Some of the other system costs, such asadditional balancing services, will notnecessarily be borne entirely by renewableenergy generators.

On cost reflectivity, the Renewables ObligationCertificate (ROC) price that is passed on toconsumers is set more by the lack of availabilityof renewable capacity and the ‘buyout rate’xiii

than by the comparative cost of this capacity. Infact, the technology preferences of renewableenergy investors can be seen as an indicator oflowest cost – because ROCs have a relativelystable value, these investors will tend to choosethe cheapest technology available to maximise

xii Some of this funding will support the development of offshore wind, and can therefore be attributed to the cost of windenergy.

xiii The ‘buyout rate’ is the price per MWh that electricity supply companies much pay into a central fund if they are unable toprovide ROCs up to full value of the electricity they supplied during each period. The buyout fund is then redistributed tothose suppliers that met their obligation.



their profits. Therefore, the NAO expects the ROscheme to be providing wind power generatorswith subsidies that are above the level neededfor project viability. The NAO report recognisesthat this in unavoidable in the medium term,but does recommend that onshore wind iseventually reassessed and possibly excludedfrom future RO targets, meaning it would notqualify for ROCs.

The fact that the RO does not cover networkreinforcement costs is due to the structure of theUK’s electricity system, which separatesgenerators from the companies that operate thedistribution and transmission networks. Thecosts of network reinforcement will thereforefall on the latter, who in turn will pass these onto the consumer through network charges.

A similar situation occurs for the cost ofadditional balancing services, required for higherpenetrations of wind capacity. These costs areunlikely to fall solely to wind energy generators,as they are not easy to determine in real time.They will therefore be picked up by othermarket participants (as part of the ‘BalancingServices Use of System Charges’ levied on allusers of the system), and will be passed on toconsumers.

The Government is in the process of reviewingthe Renewables Obligationxiv although the scopeof this review excludes major changes to the RO.Any future changes will not affect projects thatare already built, approved or planned – this isto avoid damaging investor confidence.

4.7 Alternatives to wind energyAlthough the above analysis shows the netadditional cost of wind to be relatively small, itis important that the alternatives to wind

energy are also considered. Below is a summaryof the main alternatives available and the rolethey might be expected to play to 2010 andbeyond.

Energy efficiencyAlthough not a fuel in itself, energy efficiency isoften the cheapest and most effective way ofreducing fossil fuel consumption and emissionsfrom power plants. This is something all sectors– domestic, commercial and industrial – cancontribute to, not only by reducing electricityconsumption but by reducing use of all fossilfuels, including gas for heating and oil fortransport. The benefits of energy efficiency arewell known, yet too often opportunities aremissed and investments are not made. TheCarbon Trust estimates that small and mediumenterprises are wasting over £1 billion onenergy per year and that many potentialinvestments could be at low or zero cost.

The Government published an Energy EfficiencyAction Plan in 2004, which sets out how itintends to achieve cuts of 10 million tonnes ofcarbon by 2010, which represents around a thirdof the emissions reductions required44. As part ofthis the Government funds schemes to makeinformation available to the public on what theycan do. Websites run by organisations such asthe Energy Saving Trust (www.est.org.uk),which focuses on the general public, and theCarbon Trust (www.carbontrust.org.uk) whichconcentrates on the commercial and publicsectors, have a wealth of information on how tosave energy or to use it efficiently. Energysuppliers are also required by Government tooffer energy saving measures (energy efficientboilers, lamps & appliances, and insulation) totheir customers, and this requirement isincreasing. However, households need to take

xiv See http://www.dti.gov.uk/renewables/renew_2.2.5.htm for further information.



up these offers to reduce their energyconsumption and undoubtedly both businessand the public sector could do much more toreduce their emissions.

Whilst energy efficiency may be cost-effective,action to reduce emissions cannot rely on italone. The DTI have been quoted as saying,“Renewable energy may be more expensive butits development is essential”45. This is becausesupporting renewable energy and other lowcarbon technologies now will create futureoptions that enhance the UK’s flexibility inmitigating climate change. We should certainlyaim to reduce our energy consumptiondramatically, but if we also find ways to supplythe remaining energy demand in a sustainableway then total emissions reductions will begreater.

CoalThe use of coal is less financially attractive andenvironmentally acceptable than in the past.The UK has agreed to a series of internationaltreaties to reduce air pollution from coal use,and the EU Large Combustion Plant Directive,which comes into force in 2008, will furtherconstrain emissions of NOx and SO2. The highcarbon content of coal and the advent of the EUEmissions Trading Scheme in 2005, which placesa value on emissions of carbon dioxide, willmake the use of coal increasingly unattractive,although in the medium term generators maycontinue to use coal as it remains cheap andreadily available. Carbon capture andsequestrationxv or ‘clean coal’ technologies mayoffer a way for coal-powered electricitygeneration to reduce carbon dioxide emissions,but such solutions will come at a cost. A large

percentage of the UK’s coal demand is alreadymet from imports and this is likely to continue.

GasThe DTI projects gas consumption will continueto rise, driven to a large degree by continuingincreases in demand from the power sector – by2010, it is expected that gas will account forbetween 38% and 52% of total electricityproduction. In 2004, for the first time, the UKbecame in net importer of gas, and prices in theworld markets rose considerably. Gas is a muchcleaner fuel than coal and is less carbonintensive, therefore air pollution and CO2

emissions are reduced. However, an increasingpercentage of gas will need to be imported – bypipeline from Norway, and Russia (passingthrough mainland Europe), and by sea asliquefied natural gas (LNG) – with implicationsfor energy diversity and fuel security.

NuclearCurrent Government policy on nuclear powerwas clearly stated in the 2003 Energy WhitePaper:

“Current economics make newnuclear build an unattractive optionand there are important issues ofnuclear waste to be resolved. Againstthis background, we conclude it isright to concentrate our efforts onenergy efficiency and renewables.We do not, therefore, propose tosupport new nuclear build now.” 46

xv One possible solution to the continued use of fossil fuels is for the CO2 to be removed from the fuel, compressed and thenstored so that it does not enter the atmosphere. Current storage options include using disused oil wells, injecting intosaline aquifers, and pumping CO2 into the ocean to be absorbed. However carbon sequestration is currently expensive andthere are a number of scientific uncertainties outstanding.



It is the SDC’s view that nuclear power has farfewer advantages to offer, in terms ofcombating climate change, than thecombination of energy efficiency, renewablesand combined heat and power - as proposed inthe Government's own Energy White Paper.Moreover, the Government has stated that anacceptable solution must be found to deal withthe existing stockpile of nuclear waste beforeany new plans for nuclear power are considered.Such a solution is currently not available.

Based on current policies, new nuclear capacityis therefore unlikely for at least another 15years, given that any decision would need toallow for full public consultation, public inquiriesfor potential sites, and then the long process ofplant construction. Without new-build capacity,nuclear is set to decline as a share of electricityproduction as plants are taken out of service –by 2010 the 14 plants currently operating willbe down to eight, and by 2020 only three arelikely to be generating. The newest plant,Sizewell B, is due to close in 2035.

Other renewablesThe Government is keen to encourage a widerange of renewables technologies to develop,which will enhance energy diversity and enablefurther emissions cuts to be made after 2020. Atpresent the most commercially viable andmature renewable technologies are onshorewind power, landfill gas, energy-from-waste,and certain forms of biomass (eg. electricitygeneration from poultry litter and straw, and co-firing in conventional plant). There are limits tothe additional capacity for both landfill gas andenergy-from-waste due to site availability andenvironmental constraints respectively.Therefore, the Government expects electricitysuppliers to favour onshore wind and biomassgenerating plant for meeting their increasingobligation to source renewable electricity up to2010. Beyond this, other renewables

technologies, such as wave and tidal power, areexpected to play an increasing role.

4.8 Projected long-term costs forelectricity generationAnother way of looking at the cost of wind is tocalculate a projection of the likely future cost.This takes a more long-term view of energypolicy, and to a great extent lies behindGovernment support for renewables.

Table 8 shows a series of projections for a widerange of electricity generating technologiestaken from the Government’s energy policyreview in 2002. This work estimated the costs inpence/kWh for the respective technologies in2020, presented in today’s prices. Theseprojected costs help to show the backgroundbehind current energy policy, and theGovernment’s position on renewables inparticular. It should be noted that since thistable was compiled, generation costs from gashave increased significantly – due to gas priceincreases. The upper end of the range is nowaround 3p/kWh for gas CCGT plant.

As this table shows, onshore wind is projectedto become the cheapest source of electricity by2020. This is due to sustained reductions in costsfor wind power plant combined with increasedcosts for fossil fuels, particularly coal and gas.The projections also show that offshore wind,energy crops (a form of biomass) and wavepower will all be cost competitive withtraditional fuel sources, particularly if CO2 captureand sequestration is included. The costs fornuclear power are based on a series ofprojections for new build using plant designsthat have not yet been built – this accounts forthe ‘moderate’ level of confidence in the priceprojections.



Of course, projections from other studies mayoffer conflicting views. The aim of presentingthis information is to show the background tocurrent UK energy policy – however, asubstantial body of research went into theseprojections, and they are well respected.

4.9 Drawing conclusions

Comparing cost estimationsThis section has presented three main sets ofinformation for the cost of wind energy, all ofwhich differ in what they are attempting toshow.

Firstly, the generated cost of wind is quiteaccurately known from a number of studies, andwould seem to be around 3.2p/kWh for onshorewind energy and 5.5p/kWh for offshore. Thisrepresents a premium over new CCGT gas-firedplant (currently at about 3.0p/kWh), and is thejustification for the Government’s supportmechanisms, which help to fill the gap andmake wind power developments viable. There isgood reason to believe that these generationcosts will fall over time as ‘learning curve’effects, innovation and larger-scale productionhelp to reduce plant costs. This is theassumption made in the PIU review, whichpredicted that onshore wind would be around1.5-2.5p/kWh by 2020, with offshore at 2.0-3.0p/kWh.

Technology Cost in 2020 Confidence inestimate

Cost trends to 2050

Coal (IGCCxvi)

Gas (CCGT)

Fossil generation with CO2

capture & sequestration

Large CHP (gas)

Micro CHP (gas)

Nuclear

3.0 – 3.5 p/kWh

2.0 – 2.3 p/kWh

3.0 – 4.5 p/kWh

Under 2 p/kWh

2.5 – 3.5 p/kWh

3.0 – 4.0 p/kWh

Moderate

High

Moderate

High

Moderate

Moderate

Decrease

Limited decrease

Uncertain

Limited decrease

Sustained decrease

Decrease

Table 8: Electricity fuel source cost projections for 202047

Conventional Fuels

Onshore wind

Offshore wind

Energy crops

Wave

Solar photovoltaics

1.5 – 2.5 p/kWh

2.0 – 3.0 p/kWh

2.5 – 4.0 p/kWh

3 – 6 p/kWh

10 – 16 p/kWh

High

Moderate

Moderate

Low

High

Limited decrease

Decrease

Decrease

Uncertain

Sustained decrease

Renewables

xv IGCC = integrated gasification combined cycle



Secondly, a number of studies have attemptedto estimate the ‘system cost’ of incorporating20% wind energy output on the UK grid by2020. This level of wind capacity represents anextreme scenario, as in reality other renewableswill make some contribution. The net systemcost is calculated by subtracting all the benefitsof wind energy (displaced fuel, avoided plantconstruction, avoided network reinforcement)from the costs (additional cost of plant, networkreinforcement, additional balancing services).This figure is very sensitive to gas pricefluctuations, and updated analysis done for thisreport suggests that with gas prices at theircurrent levels (30p/therm), the net system costof 20% wind would be around 0.17p/kWh. Thisrepresents an increase in electricity prices ofaround 3.8%. This would be the total costconsumers could expect to pay by 2020 if thetrue cost of wind generation were accuratelyreflected in the market. If the carbon benefits ofthis cost are included, it is substantially reduced,and could be negative (ie. a net benefit tosociety) if a high social cost of carbon isassumed.

Thirdly, the cost of renewable supportmechanisms has been outlined. This analysisrelies on a recent report by the National AuditOffice, which attempts to determine the cost toconsumers and taxpayers of supportingrenewable electricity generation. The NAO statesthat two thirds of this support is in the form ofthe Renewables Obligation, which providesinvestors with a financial incentive (in the formof ROCs) to invest in renewables. Consumersupport through the RO will cost around £1billion by 2010, equivalent to a 5.7% increase inthe price of electricity. For onshore wind, thevalue of ROCs is high enough to cover theadditional generation costs when compared tothe main alternative (gas-fired plant), asoutlined above. However, because theRenewables Obligation is not cost reflective, this

support is likely to be in excess of what isneeded for onshore wind to be viable at goodsites. Most public support mechanisms sufferfrom this problem, but the important point tonote here is that this makes the RO a poorindicator of the cost of wind energy. Whilegeneration costs are likely to be lower than theRO implies, other costs (such as networkreinforcement and additional balancing services)are outside its scope.

Bringing all these together is not astraightforward process. While we are confidentin the estimations of the net additional cost ofwind (the ‘system cost’), this is unlikely to bethe cost that is actually paid by UK consumers. Itseems likely that the actual cost will be acombination of public support mechanisms(which will be paid regardless to support allrenewables), and the system costs that do notfall within the scope of the RenewablesObligation. The likely cost of the RO in 2020 isunknown, as it is possible it will have beensubstantially revised by then to take account ofthe lower cost of wind power. On the otherhand, the system cost of wind energy in 2010 islikely to be far lower than in 2020, as Figure 11shows, and could be close to zero if gas pricesare high.

The costs of current policies on encouragingrenewables, which are leading to a rapidexpansion of wind energy, are well understood,and do not appear to be excessive. The cost ofwind power itself, often assumed to be high,seems likely to be lower than the cost of thesepublic support mechanisms, and a calculation ofthe net system cost does not present anyexcessive price increases.

Comparing the alternativesGovernment support for renewables should beviewed within the context of current energypolicy, as outlined in the 2003 Energy White



Paper. This stresses the need to address climatechange, whilst ensuring an adequate level offuel security. Government thinking was stronglyinfluenced by cost projections such as those inTable 8, which show renewable energy sourcesdecreasing in cost by 2020, and in the case ofonshore wind, becoming competitive withconventional plant. Policies that encourage thedevelopment of renewables are therefore aimedat stimulating these cost reductions, recognisingthat this will require public support and subsidyin the medium term.

The SDC does not believe there is a choice to bemade between supporting energy efficiency onthe one hand, and renewables on the other.Both are needed to enable the UK to achieve itslong-term objective of a 60% cut in CO2emissions by 2050. Although support for energyefficiency may be more cost effective atpresent, supporting renewables now increasesthe choices we will have in the future and forthis reason should be encouraged. Compared tofossil fuel or nuclear powered plant, windpower, along with other renewables, offers theonly truly sustainable and secure option forelectricity generation over the long term. It isfor these reasons that it deserves public support.

FURTHER INFORMATION

DTI Renewables website –www.dti.gov.uk/renewables


5 Wind power and planning

Summary• Small and medium-sized wind power planning applications are dealt with by local planning

authorities

• Large projects are handled directly by the Secretary of State for Trade and Industry or theScottish Executive

• Planning policies exist for each UK nation to provide guidance for local decision makers onrenewable energy developments

• An Environmental Impact Assessment is required for most wind farm developments – this mustbe comprehensive and fully implemented

This section takes a closer look at the planningsystem and planning policy for wind energyprojects. The planning policy environment andconsents procedure are gradually improving –and will need to continue to do so – if the UK isto meet its targets for renewable energydevelopment.

5.1 Planning process for windprojectsAll wind developments in the UK have to applyfor planning permission and/or consent. For allonshore energy projects in Great Britain over 50MW in capacity, and those over 1 MW offshore,planning consent is not provided by the localplanning authority, but is dealt with directly bythe Department of Trade and Industry (DTI) (forEngland and Wales) or the Scottish Executive (forScotland) under Section 36 of the Electricity Act1989xvii. All other projects are dealt with by thelocal planning authority.

In Northern Ireland, all wind developmentsrequire planning permission from theDepartment of Environment, and under Article39 of the Electricity (NI) Order 1992, all energy

projects over 10 MW must also obtain consentfrom the Department of Enterprise, Trade andInvestment.

For larger wind power projects (usually thoseover 5 MW), the wind developer is legallyrequired to produce an independentEnvironmental Impact Assessment (see Box 5),which should investigate specific concerns suchas landscape, noise and wildlife effects. Theresults of the EIA are published in anEnvironmental Statement (ES), which is apublicly available document that will be used inthe consents process. It is accompanied by anon-technical summary, which should be writtenin an accessible way and be available free ofcharge, usually from the developer. Manydevelopers will put this information on theirwebsites, a form of good practice that should beencouraged.

Local planning decisionsFor wind power projects under 50 MW, thedeveloper will need to apply for planningpermission from the local planning authority(LPA). In England, planning is usually the

xvii The Electricity Act 1989 only applies to the Renewable Energy Zone adjacent to Northern Ireland’s territorial waters; it doesnot cover onshore or territorial water areas.



responsibility of district councils, except in areaswith single-tier unitary authorities, such as somemajor cities. In Scotland and Wales, planningpermission is dealt with by single-tierauthorities, and in Northern Ireland theAssembly takes direct control of planningdecisions through six regional offices.

In most cases, planning applications will firstlybe considered by LPA officials, who will checkthat proposed wind farm developments are inline with national, regional and local planningpolicies, before considering the EnvironmentalStatement from the developers (if appropriate)and the responses to the public consultation.They will then make a recommendation to theplanning committee, which is composed of localcouncillors and must make the final decision. Ifthe planning application is rejected thedeveloper may take their case to the relevantappeal body, which has the power to overrulethe original decision if it considers that it:

a) Was a significant departure from national,regional or local planning policy;

b) Did not fairly assess the balance of nationalor local environmental, social or economicconsiderations.

A developer is also entitled to go to appealfollowing non-determination after the statutoryperiod of eight weeks, or 16 weeks forapplications where an EIA has been carried out.

There are three appeal bodies depending on thejurisdiction of the original decision: The PlanningInspectorate (with responsibility for England andWales), the Scottish Executive Inquiry ReportersUnit, and the Northern Ireland Planning AppealsCommission. These report directly to theirrespective national governments. The appealbody may request written or informalrepresentation, or it may decide to open a public

inquiry – the latter option is often taken for morecontroversial or complicated wind farm proposals.

Finally, the Secretary of State with responsibilityfor local government and planning issues (forprojects in England, Wales and NorthernIreland), and the Scottish Executive (for projects in Scotland), have the power to‘call in’ planning applications for a decision tobe taken centrally through a variety of means.For example, schemes may be ‘called in’ if theyraise issues of national importance or are asignificant departure from the structure plan ornational planning policy. In general, this poweris used with caution.

National consents processOnshore wind farm projects over 50 MW in sizeare automatically dealt with by the Secretary ofState for Trade and Industry (in England andWales) or the Scottish Executive (in Scotland).This process comes under Section 36 of theElectricity Act 1989 and requires the DTI orScottish Executive to consider all the argumentsfor and against the proposed developmentbefore awarding consent. A local public inquirymay be held. Deemed planning permission willusually be awarded at the same time underSection 90 of the Town and Country Planning Act1990.


Case StudyCommunity Support for Wind Power – Swaffham, Norfolk

Swaffham is one of Norfolk's most attractivemarket towns, featuring two of the mostpopular wind turbines in the UK. Over 60,000local people and visitors have climbed the300-step spiral staircase inside the Swaffham1 turbine to reach the unique 65m highviewing platform designed by Foster &

Partners, situated below the hub. There issimilar enthusiasm for Swaffham 2 in SporleRoad, Swaffham. Together the two turbinesgenerate enough electricity to supply 75% ofSwaffham’s total domestic electricityrequirements, boosting Norfolk’s total windpower by 30%.

Swaffham I proved so popular with the locals that they called for Swaffham 2 to be built despite opposition from the thenPrincipal Planning Officer who is now a wind convert.

“I moved back to Swaffham after being away for 10 years and was delighted tosee the generator in the skyline.. much better than cooling towers or chimneys.”

Paul DowdenSwaffham on BBC Norfolk Talk

“I love the wind farms we have in Norfolk, they add to the scenery. I lovedriving past the Eco-centre at Swaffham. I have to slow down and gawp… Iwould be very happy to live next to one no problem.”

Ron Luton-BrownNorwich on BBC Norfolk Talk

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Case study: Community Support for Wind Power – Swaffham, Norfolk

There was overwhelming local support whenthe installation of Swaffham 1 was mooted backin 1999 by Ecotricity. The District Councilreceived seven letters of official response –three for, three against and one saying it mightbe acceptable if the colour was right. Oneperson who wasn’t in favour was Greg Britton,then Area Planning Officer of Breckland DistrictCouncil, who was converted to wind energyonce he became aware of the amount ofpollution generated by fossil fuels in theproduction of electricity.

The local community was generally enthusiastic.When Ecotricity mailed 100,000 households inBreckland asking residents to say ‘Yes’ or ‘No’ tomore wind turbines as part of the publicconsultation on plans for Swaffham 2, around89% of the 9,000 respondents voted ‘Yes’. Only6.5% said ‘No’ and some 3.6% were eitherundecided or left their vote blank. Greg Brittonrecalls that 26 letters were sent to the planningdepartment over Swaffham 2 – 23 of whichwere support letters, including three fromdistrict councillors. Construction started in theApril and Swaffham 2 was completed on 18thJuly 2003. At the time of building it was theUK’s tallest onshore wind turbine.

Now Principal Planning Officer, Greg Britton islooking forward to eight more turbines going upnear North Pickenham, a small village four milesSouth East of Swaffham.

“The biggest objector to the erection of wind turbines in Norfolk was me. I hadnever seen one other than in a photograph but I knew that they were wrong forNorfolk. In meetings with Ecotricity I was the one saying ‘No’. However oncethe application had been submitted and I became aware of the amount ofpollution generated by fossil fuels in the production of electricity I becameconvinced that turbines were an option. I watched the erection of Swaffham 1and upon its completion I saw a graceful structure which contrary to my earlierviews did not detract from the historic character of the town or the surroundingarea. Subject to the assessments usual to this type of application, I now supportthe use of wind energy in Breckland for the production of electricity.”

Greg BrittonPrincipal Planning Officer of Breckland District Council and former Area Planning Officer

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Case study: Community Support for Wind Power – Swaffham, Norfolk

Lessons and thoughts:

• It is interesting to note that Swaffham 2 received a higher level of support than Swaffham 1 – thisindicates that communities can grow to like wind turbines once they have local experience ofthem.

• Good local engagement can increase levels of public support for wind power, leading to furthersuccessful developments in nearby areas.

Key facts:

Swaffham 1

• Ecotricity developed and built the first multi-megawatt 1.5 MW capacity wind turbine at theEcotech Centre in Swaffham in 1999.

• The first of a new generation of direct drive, variable speed wind turbines has a hub height of67m, 31m blades, and a rotor diameter of 66m.The turbine rotates at between 10 -22rpm(depending on wind speed).

• The turbine is around 360m from local housing but there have been no noise issues or complaints;a light sensor is installed for shadow flicker.

Swaffham 2

• Construction of the second 1.8 MW turbine was completed on 18th July 2003 at Sporle Road,Swaffham, Norfolk. The hub height is 85m, length of blades 32m, and rotor diameter 70m.

• For further information: www.ecotech.org.uk, www.ecotricity.co.uk

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Box 5

The Environmental Impact Assessment procedure ensures that the likely significant environmentaleffects of development projects and their mitigation measures are identified and taken into accountin planning consent procedures. The main product of the EIA procedure is the EnvironmentalStatement (ES), compiled by the developer, which must accompany those planning applications thatfall into either Annex I or II of the EIA Directive. The requirement for public involvement means thatsubmission of an Environmental Statement must be advertised and copies made available for publiccomment. It must also be circulated to relevant statutory consultation bodies. The GeneralDevelopment Procedure Order (1995) sets out the relevant consultees for particular types ofdevelopment.

Environmental Impact Assessment

The EC Directive on Strategic Environmental Assessment was transposed in many EU Member Statesin July 2004 after a gestation period of a decade or so. Its objective is to:

“…provide for a high level of protection of the environment and to contributeto the integration of environmental considerations into the preparation andadoption of plans and programmes with a view to promoting sustainabledevelopment, by ensuring that, in accordance with this Directive, anenvironmental assessment is carried out of certain plans and programmeswhich are likely to have significant effects on the environment.”

It is an iterative and systematic process, carried out at a strategic level, to identify, predict and reporton environmental impacts. It must also identify and give proper consideration to feasible alternativeoptions within plans or programmes. The 2004 SEA Regulations cover certain plans and programmesprepared for town and country planning or land use, agriculture, forestry, fisheries, energy, industry,transport, waste management, water management, telecommunications and tourism. At present, anSEA is not required for proposed wind farm developments onshore. However, in Scotland, theEnvironment Assessment (Scotland) Bill (which is currently under discussion in the ScottishParliament) would extend the scope of SEA beyond the terms of the Directive. It aims to ensure thatall public sector plans, strategies and programmes are scrutinised for their environmental impact.Although wind farm developments will not automatically be exempt from conducting an SEA, it isunlikely that individual wind farms would qualify.

Strategic Environmental Assessment


5.2 Planning policyPlanning policy is devolved to nationalgovernments, so England, Scotland, Wales andNorthern Ireland have separate policies. Policy inrelation to renewable energy has recently beenupdated by the Office of the Deputy PrimeMinister (which has responsibility for England), bythe Scottish Executive in Scotland; the WelshAssembly Government in Wales is due to issue itsrevised advice shortly. The underlying aim hasbeen to provide clearer guidelines for theconsideration of renewable energy projects andto improve the consistency of decisions. This is inline with wider energy policy (as outlined in the2003 Energy White Paper) and was seen asessential for renewable energy targets to be met.

EnglandPlanning Policy Statement (PPS) 22:Renewable Energy sets out the Government’snational planning policies for renewable energyprojects in England. It covers national polices inrelation to the siting of wind farms generally,and those in close proximity to NationalDesignations – National Parks, Areas ofOutstanding National Beauty (AONB), HeritageCoasts, Green Belts and other local designations.It advises that in areas with nationallyrecognised designations or Green Belt status,planning permission for wind farms should onlybe granted where it can be demonstrated thatthe objectives of the designation will not becompromised and any significant adverse effectsare outweighed by the environmental, socialand economic benefits. PPS 22 is publishedalong with a companion guide, which offerspractical advice for decision-makers on howprojects can be implemented on the ground.

ScotlandNational Planning Policy Guideline (NPPG) 6,Renewable Energy Developments sets out theScottish Executive’s national planning policies forrenewable energy projects in Scotland and sets

outlined siting considerations for wind farms atthe national level. It states that issues to beconsidered include visual impact, landscape, birdsand habitat. In relation to national designations, itadvises that renewable energy projects shouldonly be permitted where it can be demonstratedthat the objectives of designation and the overallintegrity of the area will not be compromised orany significant adverse effects on the qualities forwhich the area has been designated are clearlyoutweighed by social and economic benefits ofnational importance.

Planning Advice Note (PAN) 45 provides adviceon good practice on Renewable EnergyTechnologies in Scotland. In relation to the sitingand design of wind farms, PAN 45 reinforces thefact that, given the Scottish Executivecommitment to address climate change, it isimportant for society at large to accept windfarms as a feature of many areas of the Scottishlandscape for the foreseeable future. It does,however, emphasise the need to take account ofregional and local landscape designations in thesiting of wind farms. It stresses a cautiousapproach in relation to particular landscapeswhich are rare or valuable, such as NationalScenic Areas (NSAs), National Parks and theirwider settings. In these locations it is difficult toaccommodate wind turbines without detrimentto national heritage interests. PAN 45 suggeststhat areas recovering from past degradation andthose not especially valued may be appropriatefor wind farm development.

WalesTechnical Advice Note (TAN) 8 was originallypublished in 1996, and the updated TAN 8 willoutline the Welsh Assembly Government's aimto secure the right mix of energy provisionwhilst minimising the impact on theenvironment and reducing the overall demandfor energy. To meet the Assembly's renewableenergy target of 4,000 GWh per annum by 2010,




the policy aims to achieve 800 MW fromstrategic onshore wind energy development.The Welsh Assembly Government considers thata few large scale (25 MW+) wind farms could becarefully located to meet the target. The draftTAN 8 identifies seven Strategic Search Areas(SSAs) in Wales which are considered relativelyunconstrained. The identification methodologywas developed by Assembly consultants using aland use sieve approach and combining thiswith information about the capacity of theexisting and proposed grid network. Localplanning authorities are encouraged toundertake more detailed mapping andlandscape assessment work to formulate localpolicies for development of large and smallscale wind farms in the SSAs and for smallerwind farms outside the SSAs. Communityinvolvement at early stages in the developmentof policies and proposals is encouraged. TheWelsh Assembly Government is due to issue therevised and agreed TAN 8 by summer 2005.

Northern IrelandCurrently there is no planning policy statementfor renewables in Northern Ireland. In August2004 the Planning Service launched aconsultation paper entitled Reforming Planning,which sets out to reform primary planninglegislation in Northern Ireland. This couldeventually lead to a stated planning policy onthe development of renewable energy.

5.3 Current development plansAs most wind developments will go through thelocal planning system, reliable data can bedifficult to obtain. However, Table 9 provides arecent summary of wind power applications thatare being dealt with by the local planning systemthroughout the UK. Data on Section 36 projectscan be obtained from the DTI and ScottishExecutivexvii.

xviii Please see http://www.dti.gov.uk/energy/leg_and_reg/consents/index.shtml andhttp://www.scotland.gov.uk/Topics/Business-Industry/infrastructure/19185/18734 for further information.

Post consent Pre Consent

Under construction Awaiting construction Application beingconsidered

Application beingprepared

484 MW 686 MW 5,861 MW 4,200 MW

Table 9: Wind power applications in the UK local planning system48

FURTHER INFORMATION

Planning Policy Statement (PPS) 22 – Office of the Deputy Prime Minister -www.odpm.gov.uk/stellent/groups/odpm_planning/documents/pdf/odpm_plan_pdf_030334.pdf

National Planning Policy Guideline (NPPG) 6 – Scottish Executive -www.scotland.gov.uk/library3/planning/nppg/nppg6.pdf

Planning Advice Note (PAN) 45 – Scottish Executive -www.scotland.gov.uk/library/pan/pan45.pdf

Technical Advice Note (TAN) 8 – Welsh Assembly Government -www.wales.gov.uk/subiplanning/content/tans/tan08/tan8_home_e.htm


6 Landscape and environment

Summary• The landscape of the British Isles has changed dramatically through human development over

the past 5000 years and very few landscapes pre-date this

• Climate change will have a radical impact on our landscape, and wind developments must beviewed in this context

• Landscape and visual impacts are important environmental considerations for winddevelopment applications, yet reaction to these is highly subjective

• Overall there are far fewer landscape and environmental impacts associated with wind turbineswhen compared to the alternatives – and most of the impacts can be reversed quite quickly

• Wind developments can be in areas that have never had any energy generating technology inthe past and are often met with greater resistance

6.1 BackgroundThis chapter looks at landscape, visual andenvironmental issues related to the siting of winddevelopments. A sustainable approach demandsthat the issue of wind power is consideredalongside competing alternatives, all of whichalso have landscape and environmental impacts.There is also a need for the cumulative impact ofwind developments on the landscape andenvironment to be considered, as all energydevelopments will eventually result in associatedimpacts as a result of network expansion andupgrades.

With increasing pressures on energy policy andthe need to reduce emissions of carbon dioxide,it is hard for any community to be consideredexempt from the task of delivering a low carbonfuture. As climate change presents the mostserious threat to UK landscapes, technologiesthat help limit our contribution to climatechange should be encouraged, even where thisrepresents a temporary loss of amenity.

This section provides a synopsis of the differenttypes of wind farms, their landscape and visualcharacteristics, wind farm design issues andresulting landscape and visual effects which

may cause change to the existing UK landscape.It also looks at the environmental impact ofwind developments and the main non-renewable alternatives.

Taking a holistic sustainable development viewdoes not automatically mean a ‘green light’ forwind developments, as it would requireconsideration of a wide range of landscape,natural heritage, and environmental issues aswell as social and economic ones.

6.2 Landscape changeOne definition of landscape is ‘an extensive areaof scenery’. This does not do full justice to thecomplexity of the term, which is betterdescribed as ‘habitat plus mankind and theresulting combination of patterns, perceptionand process’. The Landscape Institute defineslandscape as ‘the whole of our externalenvironment, whether within urban or ruralareas’. This document should not be regarded asdefinitive guidance on this subject, which iscovered in a number of technical publicationsand detailed guidance documents.


The British Isles has a remarkable diversity oflandscape. The post-glacial empty wildernesshas been transformed over the last 10,000 yearsinto the living landscape of the 21st century. Theoutline of the British Isles was shaped by therising sea and its separation from mainlandEurope with subsequent colonisation of the landby the forests and the arrival of the first fauna.The encircling seas give the islands a temperateclimate and a wealth of marine life. Around5,000-6,000 years ago, early man initiated thelong process of transforming the wilderness intothe landscape that is familiar today. Landscapesare not static; they have always been changingand will continue to do so, adapted by humanneeds and economic activity, and affected byfuture climate change. They are in a constantstate of dynamic equilibrium which cannot befrozen at any one point in time.

Wind projects are just one of the many forms ofdevelopment that may bring about landscapechange in the UK. However it is worth bearing inmind that wind turbines are not permanentstructures and once removed the landscape canusually return to its previous condition –although roads may remain for a considerableperiod of time after a site has beendecommissioned. This is provided that winddevelopments do not lead to land-take by otherdevelopments, which should be guarded againstin protected or previously undeveloped areas.

6.3 Landscape and visual effects Landscape effects are changes in landscapefabric, character and quality as a result ofdevelopment, and differ from visual effects. Thelatter relate to the appearance of these changeswhere they can be seen in the landscape andthe effect of those changes on people.

It is recognised that landscape and visual impactis one of the key environmental issues indetermining wind farm applications, given theirtypical form, location and function. In a randomsample of 50 wind developments which hadbeen refused planning permissionxix, 85% of thereasons for refusal were on grounds oflandscape and visual impact.

Wind developments have a number ofcharacteristics which cause landscape and visualeffects. These characteristics include the turbines,access and site tracks, substation building(s),compound(s), grid connection and anemometermast(s). The assessment should take account ofany proposed mitigation measures, predict theirmagnitude and assess their significance.Landscape and visual assessments typicallyinclude photomontages from a number ofviewpoints to illustrate what a wind farm maylook like when it is built – see Figure 14.

They may also include Zone of Visual Influence(ZVI) maps which illustrate where a wind farmmay be seen from over a given area of landscape.

If a wind farm is designed with sensitivity to thesurrounding landscape, then visual impacts canbe reduced. Scottish Natural Heritage hasdeveloped guidelines to aid in the proper designof wind farms in order to minimise theirpotential negative impacts on the landscape.The components of the wind farm should beconsidered relative to the character of landscapein terms of the value of landscape, theexperience of landscape, visual composition andthe relationship with existing developments.


xix Information provided by BWEA



Figure 14: Wind farm photomontage

Figure 15: Wind farm Zone of Visual Influence (ZVI) map

Cwm Llwydd - amount of most visible turbine seen

No turbines visible

Blades, no hubs

Hub and upper tower

Rotor and lower tower

Base (1m) of tower

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6.4 Visual characteristics of windfarms

OnshoreThe visual characteristics of wind turbines varywith their make and model. Simple andsculptural forms of turbines using three bladesgenerally appear most appropriate, and theseare the designs that have become the industrystandard.

Onshore wind developments in the UK vary insize from a one turbine to large-scaledevelopments containing over one hundredturbines. The average size of winddevelopments in the UK is around 10-20turbines.

Wind developments from the early 1990s,during the early days of the UK wind industry,typically used turbines with a capacity range of300-400 kW. Over the last 10 years or so turbinetechnology has evolved, and turbines today cangenerate up to 3 MW each; a ten-foldimprovement in as many years. There arepractical limits for onshore sites, as largerturbines and towers become difficult totransport by road. This is likely to put aneventual brake on the upward trend in turbinesize.

Today’s wind turbines typically have the hublocated up to 90m above the ground withturbine blades that sweep a radius of between40m and 45m, giving the total tip height fromthe ground to the tip of the vertical rotor, the‘blade tip height’, of between 60-120m. Themost recently built wind farms typically haveturbines with blade tip heights of 100m andabove. As a comparison, the height of Big Ben is

100m, the Glasgow Tower 105m, and theLondon Eye 135m. Future turbine developmentsmay lead to improved performance along withincreases in height and rotor diameters. Recentwind farms have fewer, larger machines withbigger blades, operating at lower rotationalspeeds. Arrays of these larger turbines are lessdense because of the increased spacingbetween the turbines, but this extends theirvisual influence over a wider overall footprint.

Although the visibility and impact of wind farmsincreases with larger turbines, it is often difficultto discern relative differences in turbine heights,especially at a distance. It is generallyconsidered better in terms of visual impact for awind farm to have a lesser number of largerturbines rather than greater numbers of smallerturbines.

OffshoreOffshore wind farms are sited at sea off themainland coast, either within territorial watersor the newly created Renewable Energy Zonexx.There are less constraints on size for offshoreturbines and so larger capacities are beingdeveloped – up to 5 MW over the next decade.Typically, they share some of the same visualcharacteristics as those onshore, but they canalso include navigational markings, night-timelighting, offshore substations and onshore gridconnections. Use of these markings depends onthe variability of the coastal edge, variablevisibility with weather conditions and the effectsof curvature of the earth.


xx All current offshore wind farms are within territorial waters.


North Hoyle Offshore Wind Farm

Offshore wind developments tend to havehigher turbines and more of them, but theirlandscape and visual impact is generally lessgiven their distance from the coastline.Nevertheless, the coastal landscape is oftenunique and offers some of the most highlyvalued landscape in the UK, so developmentscan be sensitive.

In the UK, offshore wind projects are currentlybeing built at distances of between 2-10kmsfrom the shore, in relatively shallow water, butnew applications will be submitted for sitesmuch further out to sea, including some beyondthe UK's territorial waters, in the newlyestablished Renewable Energy Zone. At suchdistances these wind farms are likely to have

relatively minor visual impacts, but naturally,building and operating offshore turbines is moreexpensive, and grid connection costs can behigher. This is balanced to some degree byimproved performance offshore, but at presentthere is still a considerable difference ingenerating costs from onshore wind. Due toGovernment support, offshore wind energy isexpected to be a major contributor to the 2010targets for renewable electricity generation, andits importance is likely to grow further to 2020and beyond.

Better design and mitigationSome landscapes are better able toaccommodate wind developments than others,on account of their scale, landform and relief,and ability to limit visibility. Good design ofwind farm layouts and their relationship to theform of the landscape can help improve theirvisual acceptability.

Novar Wind Farm, Highlands

Siting is generally conditioned by technical,practical and economic reasons such as windcapture, turbulence, access, grid connection,planning and land ownership. These factors willtherefore limit the extent to which layout andsiting can be adjusted in line with aestheticconsiderations.


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A development which is grouped into a tightlyclustered array is visually more acceptable if itappears as a single, isolated feature in open,undeveloped land. But in agricultural landscapes,rows of turbines may be visually acceptablewhere formal field boundaries are an existingfeature.

Dun Law Wind Farm, Scottish Borders

The overall visual impact of a wind developmentwill principally depend on the area from where itis seen (the extent of visibility) and how itappears within these views (the nature ofvisibility). It is not necessarily whether it can beseen or not, but how it is seen and how it lookswhen it is seen. Wind developments will be mostacceptable where they look appropriate to thearea and create what is perceived as being apositive visual image. However, it is evident thatfor some, wind turbines are ugly and unsightlystructures that are out of place in any rural settingand it is unlikely that design and mitigationmeasures will be able to change these opinions.

6.5 Designated areasThe UK has many types of designated areas,with National Parks and Areas of Outstanding

Natural Beauty (England, Wales and NorthernIreland only) receiving the highest level ofprotection, along with a variety of other nationaland international designations.

The aim of high level designation is to preserveunique and valuable landscapes and areas forthe nation’s long-term benefit. All the keyplanning guidance referred to in Chapter 5recommends that planning permission shouldnot be granted for renewable energydevelopments in designated areas unless thereare strong overriding considerations and noalternative locations. In most cases this isunlikely to apply to commercial-scale windpower proposalsxxi, and a strong case cantherefore be made for maintaining a high levelof protection in areas protected for theirlandscape and aesthetic value.

6.6 Public perceptionSome people view wind turbines as gracefulstructures that complement the landscape,particularly when compared with the centralisedpower stations and power lines that have beenpresent across the landscape for many years.Nevertheless, there are also many people whofeel that wind turbines represent anindustrialisation of the landscape and areunacceptable in rural locations. Anecdotalevidence suggests that wind developmentsproposed in already industrialised areas receivefew visual complaints.

A Scottish Executive study on public attitudesshows that one in four residents living nearwind farms (26%) say that they spoil thelandscape, with visual impact the primary issuecausing people to dislike wind developments61.But the study also showed that for people living


xxi Small-scale wind turbines and other renewable energy technologies be often be acceptable within designated areas, andthere are a number of successful projects. In some cases, such technologies may help to avoid the need for additional gridinfrastructure.

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Case StudyIndustrial Wind Projects – Dagenham, London

Dagenham Diesel Centre (DDC) was opened in November 2003 as the first major buildingconstructed on Ford’s 500 acre Essex site for over 30 years. Ford invested £325 million in the state-of-the-art facility in anticipation that around 50% of all cars sold in Europe by 2006 will be diesel-powered.

Looking to demonstrate sustainable energyideas, Ford consulted with the British WindEnergy Association (BWEA) and were persuadedthat as the UK has 40% of the EU’s windresource, there was a good business case forcreating London’s first wind park as part of theregeneration of Dagenham and to generate100% cost-effective ‘green electricity‘ to helppower the Clean Room Assembly Hall.

Ford chose Ecotricity as project partners. Underthe terms of the Merchant Wind Power (MWP)initiative (providing an exclusive source of windgenerated electricity for organisations with anenvironmental agenda), Ecotricity carried out thefeasibility studies, environmental assessmentsand planning applications. This work includedconsulting with the local communities, the localairport and the RSPB ensuring the plans for theturbines located them at a suitable distancefrom the Thames to avoid any impact onmigratory birds.

The Planning Committees of Havering andBarking & Dagenham Councils granted planningpermission. The latest technology and super-quiet E66 Enercon turbines, presently the largestin the UK, were chosen and work wascompleted with the two turbines installed inApril 2004. The process took about three yearsfrom original inception to commissioning andthe turbines are now an integral part of theDagenham landscape readily visible from theA13.

The success at Dagenham follows a similarpartnership between Ecotricity and Sainsbury’sback in 2001. Sainsbury’s decided to install a

600 KW wind turbine at their East Kilbridedistribution centre in Scotland, and this was thefirst such project of its kind based on anindustrial site.

“We received no objections to thescheme. I am aware that theresponse to the Dagenham turbineshas been positive and they are seenas a beacon for the regeneration ofthe Thames Gateway.”

Martin KnowlesPrincipal Planner, London Borough of Havering

Ford UK consulted with local communities, the local airportand the RSPB.

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Case study: Industrial Wind Projects – Dagenham, London

"This scheme has made an importantcontribution towards making Londona more sustainable world city andwill help us to achieve some of thekey targets in my Energy Strategy. Ihope it will encourage other largeorganisations to consider developingsimilar schemes on their premises."

Ken LivingstoneMayor of London

”Green power from Ecotricity is fullycompetitive with our forecast energyprices and there are huge non-financial benefits too; thousands oftonnes of power station emissionsare saved by switching our electricitysource for the Dagenham DieselCentre to wind power.”

Roger PutnamFord of Britain Chairman.


• As a brownfield industrial site, theDagenham wind park plans raised noobjections on landscape, environmental orother grounds from known critics of windenergy. Development on this kind of siterepresents a huge sustainable developmentopportunity, where potential conflicts canbe minimised.

• Ford offered the various trade unionmembers the chance to visit Swaffham aswell as local residents of the two boroughsinvolved in planning permission. Visitingexisting wind farms is probably the bestway to appreciate the implications ofproposed developments.

• Ford is so pleased with the project thatthey are looking to develop wind projectsat other sites. Other large companies shouldbe encouraged to do the same, particularlywhere turbines can be situated ondeveloped company land.

Key facts:

• The 85m German produced Enercon 1.8 MWE66 turbines are some of the UK’s tallest at120m with 35m long blades and a rotordiameter of 70m

• The project has a total capacity of 3.6 MW,providing enough power to cover the needsof the Clean Room Assembly Hall..

• To find out more: www.ecotricity.co.uk;www.media.ford.com

Plans for turbnes ensured they were located a reasonabledistance from the Thames

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in the immediate vicinity of a wind farmdevelopment, only 12% said that the landscapehad been spoiled.

Essentially, the debate over whether wind farmsare destructive, benign or even positiveadditions to the UK landscape is highlysubjective. The lack of a ‘right’ or fact-basedanswer means that this debate is unlikely everto be resolved, making decisions on individualapplications extremely divisive.

However, in order to have an appreciation of theissues involved, it is also important to considerthe energy generating alternatives to windenergy, as all of these also have landscape andenvironmental impacts, many of which aretaken for granted.

6.7 Comparing landscape andenvironmental impactsThe impact that electricity generation has on thelandscape and environment depends on thetype of fuel and technology that is used togenerate it – see Table 10 for a summary. Fossilfuels such as gas and coal, and the uraniumrequired for nuclear fission, all rely on extractiveindustries for fuel supply. In the case of coal anduranium, this can have a wide and devastatingeffect on the landscape surrounding the minesite, with the associated infrastructure andwaste production contributing to a landscapeand environmental impact that can last foryears. For UK gas (and oil – although this is aminor contributor to electricity production),extraction is concentrated offshore, and suppliesof liquefied natural gas will arrive by sea.However, some onshore infrastructure will stillbe required to receive, store and distribute thegas and there are a number of environmentalissues associated with offshore exploration. And

in other countries, gas and oil are obtained fromreserves in onshore locations, where landscapeeffects will be much more pronounced.

Although many of the landscape andenvironmental effects of our fuel needs will notbe borne in the UK, a sustainable developmentapproach implies that all effects should beconsidered, wherever they occur in the world. Itwould not be equitable to suggest that landscapedestruction in other countries is justified in orderthat UK landscapes are preserved.

For combustion, all conventional power plantsrequire a large land area, and their total visualimpact would include any pylons that arerequired to link them to the national grid. Theland-take for grid connection would applyequally to wind power, although for smallerdevelopment lower voltage pylons are used, andthese tend to have a much lower visual impact.

On the environmental side, fossil fuel electricitygeneration will emit greenhouse gases andother pollutants when combusted, whichcontribute to climate change and air pollutionproblems. Coal combustion, with its high sulphurcontent relative to other fossil fuels, also causesacid rain. This particular problem can be solvedby the installation of flue gas de-sulphurisationequipment, but this is costly and many coalplants do not have it fitted. Fossil fuel powerplants (especially coal) will often cause groundpollution problems on the land they inhabit, andmany conventional plants (including nuclear)will also generate heat pollutionxxii, affectinglocal rivers or the sea. Electricity generated bynuclear fission adds to background levels ofradiation and the risks and consequences ofserious accidents require rigorous and costlymanagement and operational procedures.


xxii Heat pollution is generated through the cooling needs of conventional power plants, which often use water for thispurpose. After this has been cooled to a certain level on-site, warm water is often discharged into rivers or the sea.



Table 10: Potential environmental impacts from selected electricity generating technologies49

Fuel Type Operation Potential Environmental Impacts

All sources

Coal

Natural Gas

Transmission lines

Surface mining

Underground mining

Processing

Transportation

Conversion

Extraction

Transportation

Processing

Conversion

Land useAestheticsSafety hazardWildlife (including bird collision)

Land disturbanceAcid mine drainageSilt productionSolid wasteHabitat disruptionAesthetic impacts

Health & safety

Acid drainageLand subsidenceHealth & safetySolid wasteCoal mine methane emissions

Solid waste stockpilesWastewaterHealth & safety

Land useAccidentsFuel utilisation

Land useAir pollution

Sulphur oxidesNitrogen oxidesParticulates

Greenhouse gasesCarbon dioxide

Solid wastesThermal dischargeAesthetics

Land use (drilling)Brine disposal

Land use (pipelines)Leakage (methane emissions)

Air pollution (minor)

Land useAir pollution (relatively minor)

Carbon monoxideNitrogen oxides

Greenhouse gasesCarbon dioxide



Table 10: (continued) Potential environmental impacts from selected electricity generating technologies49

Fuel Type Operation Potential Environmental Impacts

Natural Gas (Continued)

Nuclear

Wind (onshore)

Wind (offshore)

Conversion (continued)

Mining (Uranium)

Milling (separation)

Enrichment

Conversion

Reprocessing

Radioactive waste disposal

Construction / Siting

Operation

Construction / Siting

Operation

MethaneThermal dischargeAesthetics

Land use (not extensive)

Radioactive wastesAirWaterSolid waste

Minor release of radioactive material

Land use (permanent)Thermal dischargeRelease of radionuclides (minor)Accident potentialAesthetics

Radioactive air emissions

Accident potential (handling, storage)Political instability (long term)Land use

Land disturbance (for access, minor)Land use (including access roads)AviationRadar/telecommunicationsAestheticsWildlife

Bird collisionMaintenance activities (very minor)

Seabed disturbance (construction only)Land use (shipping lanes/on-shore connection)Aesthetics (depends on distance from shore)AviationRadar/telecommunicationsMarine life

Bird collisionMaintenance activities (very minor)

Table 10 does not show the longevity of thelandscape or environmental impact that iscaused. For fossil fuel and uranium mining,these impacts can be long-lived, as is evident inparts of the UK where coal mining has takenplace. On power station sites, the large scale of

the plant and associated infrastructure meansthat extensive, permanent development usuallytakes place, and such areas are unlikely toreturn to their previous condition withoutcomprehensive decommissioning. For nuclearpower sites the land-take and associated


impacts are virtually permanent, asdecommissioned sites cannot simply bedemolished.

Decommissioning of wind turbines is a relativelystraightforward process and in most cases theland can be returned to ‘normal’ at the end ofthe turbine’s operational life, with access roadsand other impacts reversible over time in mostcases. In this sense, wind turbines could be seenas temporary structures, and siting decisionsnow do not necessarily need to becomepermanent.

6.8 Land-take by winddevelopmentsDespite claims of wholesale destruction of theUK countryside, wind power development is notlikely to have the widespread impact that manypeople imagine. To meet the 20% target for2020 solely from wind power, the UK wouldneed around 26 GW of wind capacity ifelectricity supply increases to 400,000 GWhxxiii. If50% of this is met from onshore wind using anaverage of 2 MW turbines, this would requirearound 6,500 turbines. Based on a land-take ofaround 0.18 ha/MW for the turbines, accessroads and substationxxiv, total onshore land-takewould equal around 2,340 ha. Based on a totalUK land area of 24 million hectares, this isequivalent to around 0.0001% of the totalavailable land. This contrasts with the 3.3million hectares that is currently classed as‘urban + other’ use land. As wind turbines areusually located on hilly land, the space aroundthe turbines is still available for livestock grazingor other activities and is therefore notconsidered as part of total land-take.

Figure 16: Wind turbine in front of coal-firedpower station, Grevenbroich, Germany.

6.9 Achieving a long-termperspectiveOut of all the issues surrounding wind powerdevelopment, landscape and visual impactconcerns are the only ones that are primarilysubjective. As the effect cannot be measured orcalculated and mitigation options are limited, itis unlikely that these issues can ever beresolved to everyone’s satisfaction. It thereforeseems inevitable that some people will alwaysbe objectors to wind farms in rural locations,and as UK wind resources correlate strongly withremote and rural areas, disagreement isunavoidable.

Recent changes to planning guidance across theUK requires local decision-makers to considernational energy policy priorities when decidingon local renewable energy projects, and inmany cases it is now unlikely to be enough toreject an application on landscape grounds


xxiii This figure is based on the assumptions used in the analysis by Dale et al (see Chapter 4). In reality, wind output is onlylikely to make up part of the 20% renewables target, meaning these estimates are overstated.

xxiv 0.18 ha/MW is based on calculations using data from the proposed Black Law wind farm (143 MW) being developed byScottishPower.

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alone. Considering the high level of national,and often local, support for wind power thisseems to be a reasonable approach in caseswhere there is no special landscape designation.

There is a strong case for viewing winddevelopments as temporary structures, pendinglonger-term approval on landscape grounds. Asfull decommissioning is usually possible, lastingobjections could potentially be remedied on acase-by-case basis by the eventual removal ofthe turbines at the end of their working lives.The energy options available will have changedby then, and other technologies may beavailable. However, it should also be recognisedthat landscape change has a long history andthat what may seem alien now may becomeaccepted over time. Evidence suggests thathostile opinion towards wind farms tend tosoften after they are commissioned, and there is

no reason to believe this trend will not bereplicated at future developments.

Any concern that UK landscapes will be ruinedby wind farm developments needs to bebalanced against the widespread harm thatclimate change itself could cause. Previouschapters have shown that wind power is apractical and viable solution to climate changeas part of the much wider societal and economicchange that is necessary. The development ofonshore wind power will make a majorcontribution to meeting renewable energytargets and it is not practical to expect offshorewind, which is significantly more expensive, todo this alone.


FURTHER INFORMATION

Countryside Agency - www.countryside.gov.uk

Department of Environment, Food & Rural Affairs - www.defra.gov.uk/wildlife-countryside

Countryside Council for Wales - www.ccw.gov.uk

Campaign to Protect Rural England - www.cpre.org.uk

Campaign for the Protection of Rural Wales - www.cprw.org.uk

Scottish Natural Heritage - www.snh.org.uk


7 Wildlife and ecology

Summary• The interaction between wind farms and birds, other wildlife and natural habitats is highly site

specific

• Wildlife and habitat impacts are best mitigated through careful project location, design measures,and appropriate construction techniques in the first instance

• Developers are required to undertake an Environmental Impact Assessment for all major windprojects, which must be comprehensive and of a high quality

• Not all wind developments will be acceptable, but with careful siting and strategic planning themost sensitive sites can be avoided

• So far, the UK has avoided cases of significant negative impacts on birds from wind developments,and this record must be preserved

7.1 BackgroundThe natural heritage of the British Isles is uniqueand diverse. Despite centuries of extensivehuman development and interference, the UK ishome to a large number of bird species andcontains a wide array of designated sites thatrepresent a significant percentage of the totalland area (around 7%50). Alarmingly, climatechange will have damaging and wide-rangingeffects on wildlife and ecology, with widespreaddisplacement and possible extinctions ofsensitive species.

Virtually all organisations involved in natureconservation recognise this threat and are unitedin their support for measures to help combat it,including renewable energy. However, there isalso concern that these measures should notcompromise existing conservation efforts andthat renewable energy installations in particularshould be sited in such a way as to limit theirimpact on surrounding habitats and affectedspecies. This is consistent with the application ofsustainable development principles, whichrequire a holistic approach to such issues thatrespects natural limits and adopts aprecautionary approach where currentinformation is insufficient.

Balancing these concerns is a difficult task, andone that requires a wide spatial overviewcombined with access to detailed and specificenvironmental information at the local level.Planners and decision-makers will need toconsult widely, and will want to ensure that anyStrategic Environmental Assessment and/orEnvironmental Impact Assessment is of a highstandard and has identified the risks posed bythe development. Only then can informeddecisions be made, and avoidance or mitigationmeasures discussed, if available.

This chapter looks at the potential effects ofwind power developments on wildlife andecology, concentrating particularly on habitatsand birds. More detail is available in Annex E.

7.2 HabitatsThe majority of onshore wind developments arebased in upland areas, with upland moorlandbeing the most common vegetation type. Therehas recently been a move by some winddevelopers to try to site projects largely withincommercial forestry plantations in upland areas.For low biodiversity habitat this can be apositive use of land which has already beenchanged, and has less ecological and natureconservation value. Greater habitat diversity and



reinstatement can be encouraged as part of such development. However, not all forestry plantationsare suitable, as they may be key to restoring large, uninterrupted, biodiverse areas of habitat that havebeen degraded by planting.

Box 6

The Birds Directive was adopted by the European Union in 1979, representing the first directive onnature conservation. It is now the primary tool for delivering against EU obligations under globalconventions. The Habitats Directive was adopted in 1992 and together both directives haveestablished a set of standards and norms that are now in common use.

They require Member States to:

• Take measures to conserve all naturally occurring bird species across the EU

• Classify as Special Protection Areas (SPAs) the most suitable territories for species listed on Annex I of the Birds Directive and migratory species*

• Classify as Special Areas of Conservation (SACs) a sufficient area of the habitats set out in Annex Iand of the habitats of the species listed in Annex II of the Habitats Directive in order for them tobe maintained or restored to favourable conservation status.

• Maintain SPAs and SACs in Favourable Conservation Status.

• Follow the procedure outlined in Article 6 of the Habitats Directive for carrying out appropriateassessments of environmental impacts on SPAs and SACs.

Article 6 is translated into GB law in the Conservation (Natural Habitats, &c.) Regulations 1994xxv.Regulations 48, 49 and 53 set out that:

• If a project is likely to have a significant effect on a SPA/SAC then an Appropriate Assessment hasbe undertaken of the implications of that project on the site’s conservation objectives.

• The decision-maker can only give consent to the project having ascertained that there will not bean adverse effect on the integrity of the site.

• If this cannot be ascertained, then consent for the project can only be given if it can be proved thatthere are no less damaging alternatives available to meet the project needxxvi, and then that thereare imperative reasons of overriding public interest for the project to proceed.

• Should a damaging project be consented after passing these tests, compensatory measures arerequired to maintain the integrity of the Natura 2000 network (SPAs/SACs).

Birds and Habitats Directives

xxv In Northern Ireland: The Conservation (Nature Habitats, etc.) Regulations (Northern Ireland) 1995xxvi This includes alternative sites for the project that would be less damaging to the environment, and alternative means to

meet the project need (eg: energy efficiency).


The use of brownfield sites for winddevelopments is likely to be far lesscontroversial in environmental terms, byavoiding some of the ecological and landscapeimpacts mentioned. There are numerouslocations – for example on industrial sites ordisused mines and quarries – that present viableopportunities for wind farms. Such sites mayalso be close to large electricity loads, such asoperational factories, or urban areas.

It is difficult to generalise on the significance ofspecific habitat loss, since it depends on theparticular location, habitat types and the pastmanagement. The loss of a species poor,common habitat is generally less significantthan that of rarer or more diverse types. Habitatloss comes from the turbine bases plus thenecessary access tracks, borrow pitsxxvii andquarries in wind farm development. Lossescaused by connection to the grid depend on theterrain and the method of connection –underground cable, wooden pole line or pylonline. Above ground connection generally causesless habitat damage than undergroundconnection as it can follow existing tracks or lowvalue habitats. However, visual impact is greaterfrom over-ground connections and there may bean associated collision risk for birds. It istherefore essential that the options are assessedon a case-by-case basis.

Not all habitat loss is necessarily permanent ifthe location is carefully chosen and correctconstruction methods are used. Habitats can becreated or returned above turbine bases and onconstruction compounds during the life of thewind farm, and, for sites not protected under EUlaw, the compensation provided for habitat losscan provide benefits for the future managementof surrounding habitats. However, even the

provision of various compensation habitats willnot always replace what is lost. Sensitivehabitats, such as active peatland and ancientwoodland, take a long-time to develop and arehard to replicate. For this reason, they are oftenprotected through EU and national designations,and cannot normally be compensated for.

7.3 PeatTwo important issues for upland habitats are thepotential effects on the water regime of peatbodies underlying peatland habitats. Peat is anon-renewable fossil fuel and as such should beprotected from degradation – serious damagecan result in the release of methane, a potentgreenhouse gas in itself, which could reduce thecarbon savings from the installed wind turbines.It is also a valuable habitat, so issues relating tohabitat conservation also need to be consideredearly in the process.

Wind farms, and in particular access roads, havethe potential to alter the hydrology of thepeatland, leading to drying and cracking, andpotential instability in peat bodies, which canresult in the down-slope mass movement ofpeat, often called a peat slide. The key toavoiding deleterious effects on peat bodies isconsideration of the wind farm location, schemedesign and environmentally sensitiveconstruction methods. These should beaddressed by the EIA where appropriate. Again,conservation bodies can help advise on theappropriateness of proposed developments –see the links at the end of this chapter.

7.4 WaterIndirect habitat loss through pollution andconstruction disturbance can also occur as aresult of careless construction practice. During


xxvii A borrow pit is a traditional name for a small quarry, often in the side of a small hill next to a track from which stone orother construction material is removed to allow the track to be constructed.


Case StudyConsultation, Environmental Assessment and Habitat Improvement – Black Law, Scotland

Over the past five years, ScottishPower and RSPB Scotland have established a new way of workingtogether to integrate habitat enhancement with wind farm development. Together they addressdiverse and complex challenges arising from the largest consented wind energy site in the UK. Thesite is being built in two phases and will eventually be home to 64 wind turbines, with a totalcapacity of 143 MW.

ScottishPower and RSPB Scotland worked closely on the Habitat Management Plan for 1,440 ha of the 1,850 site. Thisincludes the largest heathland restoration project in Central Scotland.

In 2000, ScottishPower identified sites acrossScotland for potential wind energy developmentand consulted with key stakeholders, includingRSPB, who suggested that 10% of those sitesoffered ‘significant ornithological problems’.

The company screened the inappropriate sitesout and identified Black Law as a suitablelocation. Lying half way between Glasgow andEdinburgh, it is a brown field location straddlingWest Lothian, North and South Lanarkshire.

The site meets Scottish Executive planning policyNPPG6 on renewable energy, has a good windresource and lies close to the existing gridconnections. Its relatively low wildlife interestresults from a post-war development historythat had left an inauspicious mix of poorlyrestored and abandoned opencast coal mines,commercial conifer plantation, degraded blanketbog and improved grassland. Preliminary birdsurveys showed some species of note butnothing of special significance.

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Case Study: Consultation, Environmental Assessment and Habitat Improvement – Black Law, Scotland

From this point, project development continuedin liaison with all key stakeholders, includingScottish Natural Heritage (SNH), the threeCouncils, the five different forest owners and thetwo farms that share the bog, grassland andabandoned opencast mine. The three nearestlocal communities of Forth, Carluke and Climpywere all involved in public exhibitions during thecommunity consultation phase.

ScottishPower also liaised with RSPB Scotlandand others in a broader capacity to establish aHabitat Management Plan for 1,440 ha of the1850 ha site. Key to the process was the use ofoutside expertise, such as the contribution fromthe University of Stirling on river restoration.The Plan was part of the planning conditionsattached to consent. RSPB Scotland at all timesretained its independent right to object if itdeemed it necessary. Consent was granted bythe Scottish Ministers on 13th February 2004and work on the site started the following Julywith the first phase of 42 turbines due forcompletion by Autumn 2005.

“Black Law highlights the benefits offinding wind farm sites where thereare no conflicts with conservationinterests. What has been achievedhere is a combination of renewableenergy generation, the restoration ofabandoned opencast coal miningworks and habitat enhancement.Given the wind farm did not presenta significant threat to bird life, andfollowing detailed negotiationsbetween ourselves, ScottishPower,the Councils and Scottish NaturalHeritage, we have together secured areally positive project that bringssignificant environmental benefits tothe area.”

Stuart HousdenRSPB Scotland Director

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Case Study: Consultation, Environmental Assessment and Habitat Improvement – Black Law, Scotland

Lessons and thoughts:• ScottishPower and RSPB Scotland worked closely on the Habitat Management Plan for 1,440 ha of

the site. This includes the largest heathland restoration project in Central Scotland.

• Habitat improvement will be secured through the restoration of 150ha of opencast coal mines,reducing grazing plus drain blocking on the blanket bog, and removal of 458ha of coniferplantation using mulching and whole tree harvesting, to be returned to heathland.

• Under a condition of the planning consent an Ecological Clerk of Works was appointed full timeduring the construction period. The ECoW provides advice on best practice construction methodsand ensures the development does not infringe any conservation law.

• ScottishPower aimed to minimise carbon dioxide emissions from vehicles transporting aggregatefor construction by sourcing the stone from the existing opencast coal mine. This proved to beproblematic as the stone used broke down as a result of construction traffic. The problem wasovercome by immediately adding a capping layer of high grade stone.

Key facts: • Black Law Wind Farm is on the site of an abandoned opencast coal mine, sheep and cattle grazing

farmland and commercial forestry covering around 1850ha, 2km to the northwest of Forth inLanarkshire, 3km northeast of Carluke and 1.5km from the village of Forth, South Lanarkshire.

• Three different local authorities were involved: West Lothian, South Lanarkshire and NorthLanarkshire. Seven different land owners were also involved.

• The project is in two parts: Phase 1 started construction July 2004 and will be completed Autumn2005 with 42 bonus turbines, 110 metres ground to tip, each with a rated capacity of 2.3MW.Phase 2 will involve a further 22 turbines. Total capacity from the 64 turbines will be 143 MW.

• For further information: www.rspb.org.uk/scotland; www.scottishpower.com/renewables

“At Black Law wind farm a close working relationship with RSPB Scotland helpedenormously in achieving significant benefits for a range of species includingblack grouse, curlew, lapwing, snipe, otter and water vole. Black Law windfarm demonstrates that wind farms can deliver significant biodiversity gains fora range of threatened habitats and species throughout the wider countryside.”

Alan MortimerHead of Renewables Policy, ScottishPower


wind farm planning and construction,watercourses must be carefully protected sincepollution of upland streams travels rapidlydownstream and affects habitat quality outsidethe immediate area of the development.

7.5 BirdsThe geographic location of the British Isles givesit strategic importance in the survival ofinternationally important bird populations.Seabirds nest here in their millions in coloniesaround the coasts. Wildfowl and wading birdshave important stop-over locations in theestuaries during their long migrations betweentheir wintering quarters and their Arcticbreeding grounds, and three million othersspend the winter in Britain and Ireland.

Birds can be affected by wind developments infour key ways:

• Habitat loss or damage (see above)

• Disturbance, leading to displacement orexclusion

• Risk of collision, which can result in mortality

• Barriers to movement, including cumulativeimpacts

Birds do not, or cannot, always change theirbehaviour to accommodate wind developmentsand this puts them at risk from displacement orcollision as a result of wind farm developments.

DisturbanceDisturbance from wind farms has been recordedfor both feeding and breeding birds. Many birdshave been shown to continue their livesunaffected by wind developments and breedingpopulations of many ground nesting birds haveremained the same after onshore wind projectshave been constructed.

However, some birds remain averse to windpower structures and maintain safe distancesfrom them, effectively being displaced fromfeeding or breeding grounds. To reduce suchrisk, and mitigate or avoid potential harm,assessing the importance of local, site-specificfeatures is an essential requirement of the EIA.

Collision riskCertain populations, particularly of the largerbirds of prey, appear more prone than othergroups to fatal collisions with wind turbines. Thismay be the result of a coincidence of sensitivespecies, wind turbines and good food sourcesnearby.

Susceptibility to collision is due to a range offactors including flight and sight conditions,manoeuvrability, flight behaviour/purpose andtopography, particular features that concentratebirds, such as migratory bottlenecks, or placeswhere rising winds are important for lift forsoaring species.

Most birds either fly around or over windturbines and of those that fly through, the vastmajority negotiate the structures withapparently little difficulty. Almost invariablyinstances of regular collisions occur where theEIA (or similar) preceding the development ofthe wind farm has been deficient, where largenumbers of turbines are located adjacent to highpopulations of sensitive species, or where thereis either an abundant food resource close to theturbines or where turbines lie on favoured flightpaths. In the earlier days of commercial windpower a number of developments were locatedwhere significant damage to bird populationswas caused by the development. The Tarifacomplex in Spain and Altamont Pass in Californiaare two commonly quoted examples, wheredevelopers failed to consider the impact onlarge birds of prey, leading to hundreds of



deaths. Similar mistakes have been made morerecently at Navarra in Spain.

However, despite the regularity with whichthese and other developments are quoted, thereis no evidence that these mistakes have beenrepeated at UK sites. This is due in part tosuccess in avoiding more sensitive sites,therefore continued vigilance is necessary tomaintain this position. The onus is on theplanning and consents process to ensure thatbird assessments (done as part of an EIA) havebeen thorough before making judgements onwind energy applications, thereby avoiding windfarms in inappropriate locations.

Barriers to movementThere is some concern that wind farms maypresent a barrier to movement for migratingbirds. This is because birds may prefer to flyaround wind turbine clusters rather than throughor over them. Whilst the effect on birds may notbe significant at one site, the cumulative impactcould be more serious, where series of windfarms could cause birds to fly a longer routethan usual. This would negatively affect theirenergy balance, and could lead to highermortality and lower fertility.

It is thought that wind farm design, andconsideration of the cumulative impact ofprojects along or across migratory corridors,could alleviate potential barrier effects on birds.However, more research will be needed beforethese issues can be fully resolved.

Mitigation measures and furtherresearch needsThe findings from bird studies at a number ofproposed wind developments have beeninstrumental in designing solutions to particularissues such as favoured flight paths of birds. Thisknowledge has led in some cases to therelocation or reduction of wind turbines from

wind development plans. In a number of caseshabitat improvements have been commissionedafter wind developments have been built to tryand compensate for any adverse impacts.Habitat enhancement for UK Biodiversity ActionPlan species such as black grouse, for example,should always be considered where wind farmdevelopment would potentially affect theirhabitat. Other innovative schemes are currentlyin place to improve habitat for species such asthe golden eagle, for example on Beinn an Tuircand Beinn Ghlas.

Although there have now been a number ofdetailed scientific studies conducted into theimpacts of wind developments on birds, mosthave been undertaken outside the UK. Thescientific community needs support inundertaking detailed UK studies, some of whichare currently in progress. Developers couldprovide some real assistance by making theavian studies from their assessments accessibleto the scientific community. This could be easilyachieved through the use of an internet-basedportal. They could also commit to a programmeof monitoring before and after construction, andassist the scientific community by providingaccess to wind farm sites for research purposes.Alternatively, there may be a role for licensingauthorities to require developers to undertakemonitoring as part of the consents process.

7.6 Protected mammal speciesHabitat loss is not likely to be significant fornon-avian protected species if adequateenvironmental survey work is undertaken, andacted upon, when scoping and developing thesite. Protected species of mammals such asotter, red squirrel and pine marten are unlikelyto come into contact with turbines. Oftenparticular localised issues such as the avoidanceof a regularly used mammal path can be fullymitigated by careful micro-siting of an accessroad or a turbine base. The operational effects



of wind turbines on protected species, with theexception of birds and bats, relate mainly tonoise, vibration and movement. These are notthought to affect the ability of animals to huntor choose a territory.

7.7 BatsBats are a species fully protected under UK andEU law. There is no evidence to suggest thatwind farms in the UK present a significantsource of mortality to bat populations, unlessthey are sited close to known concentrations ofbat activity such as summer roosts, swarmingsites, and hibernacula (over-wintering sites).Experience in the US and continental Europeshows that bats can collide with wind turbinesand there is some evidence that the levels ofmortality are increasing with the increase in sizeof the turbines. The vast majority of batfatalities (around 90%) are migratory speciesduring the migration period, rather than ‘local’bats on nightly foraging trips. Fatalities areassociated with known migration routes. In theUK there are very few migratory species and noknown migration routes.

There has been little research in the UK into batsand wind developments. As a precautionaryapproach it is increasingly important, as winddevelopments increase in size and number, thatall sites are assessed for bat flight activity aspart of the planning process so that potentialimpacts can be avoided and/or reduced throughdesign. Typical onshore wind farm sites arelocated in areas that generally do not providegood foraging or roosting habitat for bats,although this does not remove the need forproper site surveys and assessments. The ‘bestpractice’ approach would be to avoid as muchloss of bats’ foraging habitat as possible or toreplace it locally.

There is no evidence that wind turbines produceultrasonic sounds that could either attract orrepel bats.

7.8 Good environmentalassessmentThe potential environmental impactssummarised above must be examined at a veryearly stage in the development process toensure that inappropriate sites are not proposed.Ideally, spatial strategies for wind farmdevelopment, at the SEA level or higher, willhelp to ensure that low impact locations areselected. For individual developments, the EIAmust then be comprehensive and of a highquality, to enable local decision-makers andother stakeholders to identify any problems, andplan mitigation measures where possible.

A thorough EIA can only avoid such problems ifthey fall within its scope and its keyrecommendations are acted on. Conservationorganisations can help to make objectivecomments on proposals and are often consultedearly on by developers. It is worth noting thatmost of the major wildlife conservationorganisations, including the Royal Society for theProtection of Birds (RSPB), English Nature andScottish Natural Heritage, are supportive of windpower as a way of mitigating against climatechange, which will have serious consequencesfor birds and other wildlife. However, whereevidence suggests that the impacts on wildlifeof individual wind farm proposals will beunnecessarily or unacceptably large the sameorganisations will object to those developments.

7.9 The way forwardThis section has shown that there are a numberof distinct areas of concern that relate to thesiting of wind developments. It is important thatdevelopers, communities and other stakeholdersidentify these issues early on in the process,consult wildlife and conservation groups, and




agree mitigation solutions and habitatimprovement schemes where appropriate. Theplanning system requires that full EnvironmentalImpact Assessments are conducted for all majorwind projects so that these impacts can beidentified, and avoided, or mitigated throughsiting, design or habitat improvement wherepossible. This will be possible only where theEIA is well scoped and of a high quality, andultimately it is the responsibility of thedeveloper to ensure that this is the case.

The UK has a good record on the quality of windprojects and so far has avoided some of thesiting mistakes made at a small number ofinternational sites – a fact recognised by theRSPB51. There may be scope for licensingauthorities to require more stringent mitigationand compensation measures, and a programme

of monitoring, within the financial constraints ofthe project.

Of course, not all proposed wind powerdevelopments will be acceptable, and in somelocations there may be grounds for them to beactively discouraged. Spatial strategies, such asthe Regional Spatial Strategies in England andthe Strategic Search Areas in Wales, offer theopportunity to select the most suitable locationsfor wind farm development and avoid the mostsensitive, and the consideration of renewableenergy at this level should be encouraged.Following this, individual wind farm proposalswill need to be considered on a case-by-casebasis using the best evidence available and withfull input from organisations with expertise inthis field.

FURTHER INFORMATION

Windfarms and Birds - An analysis of the effects of windfarms on birds, and guidance onenvironmental assessment criteria and site selection issues – Birdlife International / RSPB -http://www.abcbirds.org/policy/OffShoreBirdLifeStudy.pdf

RSPB windfarms information - http://www.rspb.org.uk/policy/windfarms/index.asp

English Nature - http://www.englishnature.gov.uk

Scottish Natural Heritage - http://www.snh.org.uk

Joint Nature Conservation Committee - http://www.jncc.gov.uk

Birdlife International - http://www.birdlife.net


8 Noise

Summary• Turbine design has improved substantially as the technology has advanced, with noise from the

moving parts progressively reduced

• The public’s concern about noise from turbines is often related to perceptions rather than actualexperience

• Detailed studies have shown that the very low levels of low frequency noise from windturbines will not normally cause adverse health effects

8.1 BackgroundThe noise from wind developments has beenone of the most intensively studied impacts.Noise levels can be measured and predicted, but(similar to other environmental concerns) publicattitudes to noise from wind turbines dependheavily on perception and may therefore beoutdated.

As the technology has advanced, wind turbineshave generally become quieter, but noise fromwind turbines is still frequently raised as apublic concern during the planning process forwind farms.

Further detailed information on this issue can befound in Annex D.

8.2 How noise is measuredNoise is defined as any unwanted sound.Whether sound is perceived as such dependsheavily on subjective factors as well as onmeasurable aspects such as how loud the soundis, how long it lasts and the tone of the sound.

Noise is measured in decibels (dB), which is ameasure of the sound pressure level – themagnitude of the pressure variations in the air.A change in sound level of 1dB cannot beperceived except under laboratory conditions. Anincrease of 10dB sounds roughly like a doublingof loudness. Measurements of environmentalnoise are usually made in dB(A), which includes

a correction to allow for the sensitivity of thehuman ear. Typical noise levels in theenvironment are provided in Table 11.

8.3 Wind turbine noise

Mechanical and aerodynamic noiseVirtually everything with moving parts willmake some sound, and wind turbines are noexception. The sources of noise emitted fromoperating wind turbines can be divided into twocategories, mechanical and aerodynamic. Theprimary sources of mechanical noise are thegearbox and the generator. The highestcontributor to the total sound power from aturbine is the aerodynamic noise, which isproduced by the flow of air over the blades.

The sound from a single wind turbine is usuallyestimated at between 90 and 100 dB(A) at aspecific wind speed. This creates a soundpressure level of 50-60 dB(A) at a distance of40m from a turbine, which is about the samelevel as conversational speech. At a house 500maway, the equivalent sound pressure level wouldbe 25-35 dB(A) when the wind is blowing fromthe turbine towards the house. Ten such windturbines, all at a distance of 350m would createa noise level of 35-45 dB(A) under the sameconditions.

It is perfectly possible to stand underneath aturbine and have a normal conversation without


Case studyNoise Concerns – Fenland, Cambridgeshire

When local developer SnowmountainInvestments Ltd Inow known as SnowmountainEnterprises Ltd) submitted a proposal on 16th August 2000 to erect 10 industrial units,associated access road and a balancing pond atLonghill Road in March, Cambridgeshire, it wasa senior planning officer in Fenlands DistrictCouncil who commented that it might also bea suitable location for the 54,500ha region’sfirst wind turbine. The District Council, whichrepresents a population of 85,600, is an activesupporter of sustainable energy initiatives.

The amended application was submitted on 21stNovember 2000, triggering a two-year planningprocess involving a series of objections from theHome Office on behalf of HM Prison Whitemoor,which is situated 330m from the wind turbinesite. One of their primary concerns was thatnoise from the proposed turbine would beintolerable and would disturb inmates.

Local Cambridgeshire developers worked on technicaldesign issues to reduce the noise levels of the first wind turbine in the Fens.

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• The developers prepared the EnvironmentalStatement with expert help to set out areview of the issues raised and theircontext to wider national and internationalcommitments

• This project would seem to be a good useof a non-sensitive, semi-industrial site..

• Bat flights paths were a concern. Thedevelopers have commissioned a leadingUK expert to report on a second phase batsurvey between May and October 2005.

• Fenland District Council is pleased to havesupported a local developer and isconsidering applications from Powergenand ScottishPower to erect turbines inColdham, three miles North of March.

Key facts:

• The site is divided into two areas separatedby a road to HMP Whitemoor. The companygave the Home Office the access route inreturn for free access to each piece of landfor industrial and commercial purposes.

• The turbine is on the North of the site in1.25ha where there had been no proposeduse.

• The Environmental Statements included aletter from English Nature concluding thatthe proposal did not require a fullEnvironmental Statement in view of workundertaken at nearby sites.

• Confronted with noise challenges, thedevelopers were able to show that turbinemanufacturers were producing quietermachines than those detailed in theoriginal proposal and submitted this data tothe council along with a modified bladedesign.

• To find out more: www.fenland.gov.uk

In response, the developers produced evidencethat the turbine manufacturers were producingquieter machines and that they were adaptingthe blades. They also used evidence from anexisting site located 40 - 50m from HMPHaverigg in Cumbria, which uses the noisierVestas V27 turbines without any seriouscomplaints. Planning permission was finallygiven on 16th October 2002 and the decisionsigned on 7th April 2003. Construction of themodified turbine started in February 2004 andwas commissioned on 1st March 2005. Despitesome issues related to early morning shadowflicker (which have been resolved), there havenot been any noise complaints, as confirmedbelow:

“We can confirm that there are noserious noise issues from the windturbine.”

A spokesperson for HMP Whitemoor

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raised voices. Meanwhile, sheep and otherlivestock frequently graze underneath turbineswithout being driven away by the noise. Windturbines do not operate below the wind speedreferred to as the ‘cut-in speed’ – this is usuallyaround 4 m/s. Wind data from typical sites inthe UK suggests that wind speeds are usuallybelow this for about 20-30% of the time; hencethe noise does not happen all the time.

Table 11: Comparative noise levels52

Low Frequency Noise Low frequency noise (20-100 Hz) and infrasoundare issues that are frequently raised as concernsassociated with wind farm developments. Lowfrequency noise affecting sleep, such as fromventilation systems or from industrial machinery,is important as a source of environmentalconcern, especially to those of heightenedsensitivity.

Low frequency noise generation is generallyconfined to turbines whose rotors operatedownwind of the support tower – a downwindmachine. With the exception of a very fewsingle turbine installations, all current andproposed commercial wind farms in the UK have

turbines with rotors upstream of the tower.These do not usually generate low frequencynoise. Infrasound is generally defined as lowfrequency noise below the normal range ofhuman hearing. A recent review of wind turbinedata concludes that infrasound from upwindturbines can be omitted in the evaluation of theenvironmental effects of wind turbines53.

A review of low frequency noise was completedfor Defra in 2003 and concluded that the verylow levels of low frequency noise andinfrasound which occur from wind turbines willnot cause adverse health effects. In order forlow frequency noise to lead to stress symptoms,the levels must be above a certain threshold,which is very unlikely to occur for wind turbinenoise, especially when the subject is indoors54.Typically, except very near the source, peopleout of doors cannot detect the presence of lowfrequency noise from a wind turbine over theusual sound of the wind.

Research continues to take place and the DTIhave commissioned a study looking into lowfrequency noise at three wind farms in the UK.Measurements will be taken both inside andoutside dwellings and the study is due to reportin the first half of 2005.

Impulsive NoiseAlthough wind turbine sound is not usuallyconsidered to be impulsive, the aerodynamicnoise generated results in periodic audibleswishes, which whilst not impulsive in the sameway that hammering or pile driving is, can leadto a `beating’ noise effect. This type of noisegeneration is generally confined to downwindmachines and so is unlikely to be a factor formodern developments.

8.4 Noise reductionMany things can be done to minimisemechanical turbine noise, either through design

8 Noise

Source / Activity Indicative noiselevel dB(A)

Threshold of pain

Jet aircraft at 250m

Pneumatic drill at 7m

Truck at 30mph at 100m

Busy general office

Car at 40mph at 100m

Wind development at 350m

Quiet bedroom

Rural night-time background

Threshold of hearing

140

105

95

65

60

55

35-45

35

20-40

0


or retrofitting. This can include special finishingof gear teeth, using low speed cooling fans,adding baffles and acoustic insulation to thehousing, using vibration isolators and softmounts for major components, and designingthe turbine to prevent noises from beingtransmitted into the overall structure. Newermachines are already much quieter, andimprovements can be expected to advancethem further.

Noise and wind turbine operationWind turbine generated noise is a function ofwind speed and of other aspects of the designof the wind turbine. New turbine designs mayhave blades that can be pitched (rotated aroundtheir long axis). Aerodynamic noise generationis very sensitive to speed of translation at thevery tip of the blade. To limit the generation ofaerodynamic noise, large modern wind turbineslimit the rotor rotation speeds to keep the tipspeeds under about 65m/s.

In general, lower rotational speeds and pitchcontrol in upwind rotors as opposed todownwind rotors, lower rotational speeds andpitch control all result in lower noise generation.These factors are all taken into account in thedesign of modern wind farms in the UK.

Reduction of noise with distance As distance from the turbine increases, thevolume of noise is reduced. Generally, sounddecreases at 6dB per doubling of distance.Numerous other factors affect soundpropagation in the real world, includingabsorption by the atmosphere, the reflectionand absorption of sound on the ground, theblocking of sound by obstructions and uneventerrain, and by weather effects.

8.5 Noise levels in thecommunity No landscape is ever completely quiet. Thenoise from all the different sources in aparticular environment is described as ambientnoise and this can be a function of such thingsas local traffic, industrial noises, farm machinery,barking dogs and the interaction of the windwith ground cover, buildings, trees, and powerlines. It will vary with time of day, wind speedand direction, and the level of human activity.

Sound emitted from a wind turbine will blendinto background noise and decrease in relationto the distance from the tower. Even when windspeed increases, it is difficult to detect anyincrease in turbine sound above the increase innormal background noise levels caused by thewind. Wind developments may still occasionallybe audible when the wind blows becausesounds with particular frequencies or in anidentifiable pattern may be heard throughbackground noise that is otherwise loud enoughto mask those noises; this will of course dependon the distance of the listener. While noise fromoperating turbines has often been raised as aconcern, it has been shown that the noiseemitted from wind developments is generallyvery low. Probably the best way to allay anyfears over noise is to visit an operational windfarm.

8.6 Assessment of noise The response of any individual to noise is verysubjective. Whether a noise is objectionable willdepend on the type of noise (tonal, broadband,low frequency, or impulsive) and thecircumstances and sensitivity of the person whohears it. When planning a wind project, carefulconsideration is given to any noise which mightbe heard outside of nearby houses. Inside, thelevel is likely to be much lower, even withwindows open.

8 Noise


There are a number of guidelines that are usedto determine acceptable levels of noise such asThe World Health Organisation’s (WHO)publication ‘Guidelines for Community Noise’55,The British Standard BS4142, and which offers awell-understood framework for measuring allindustrial noise56. A report produced for the DTI,“The Assessment and Rating of Noise from WindFarms”, describes a framework for measuringwind farm noise and offers indicative acceptablenoise levels for developments57.

Because of the importance of background noisein determining the acceptability of the overallnoise level, it is crucial to measure thebackground ambient noise levels for all thewind conditions in which the wind turbine willbe operating. Sound propagation is a function ofthe source sound characteristics (direction andheight), distance, air absorption, reflection andabsorption and weather effects such as changesof wind speed and temperature with height.There are accepted practices for modelling soundpropagation which take all these factors intoaccount and there are a variety of propagationmodels in current usage.

The onus is on the developer to comply with thenoise limits imposed by the planning authorityfor a permitted wind power site. In the UK,information supplied with the planningapplication has to indicate whether or not theproposed turbines will meet noise limits.

8.7 Regulation of noise

UK planning controlThe noise assessments which accompanyplanning applications are reviewed by statutoryconsultees, taking into account the concerns andviews of the local community. Such noiseassessments are also frequently sent for reviewby independent noise consultants in order toverify and critically appraise the work. Noise

assessments for wind developments will needto follow the guidance and assessment criteriaoutlined in BS4142 and in the DTI report (seeabove).

Operational wind farmsFollowing the planning process, once wind farmsare in operation, then people generally livewithout noise problems from the development.Councillor Margaret Munn of Ardrossan SouthWard in Scotland comments:

“The Ardrossan wind farm has beenoverwhelmingly accepted by localpeople – instead of spoiling thelandscape we believe it has beenenhanced. The turbines areimpressive looking, bring a calmingeffect to the town and contrary to thebelief that they would be noisy, wehave found them to be silentworkhorses.”

However, other people have complained aboutnoise from wind developments in the UK. Theseare well-documented occurrences, with knownproblems relating to issues such as tonal noisefrom older wind turbines and with specificmalfunctions such as gearbox misalignment andimperfections on the turbine blades. Each ofthese issues have been subsequently addressed,whether through turbine design improvements(such as the control of tonal noise) or throughsite specific maintenance (such as thereplacement of individual turbine blades duringthe life of the wind farm).

Solutions to previous noise problems have beenintegrated into the improved design of theturbines and associated engineering. Thelocation, proximity to human habitation, designof the wind development and maintenance of

8 Noise


8 Noise

the system are all important factors inminimising noise. In addition, sophisticatedcomputer-controlled operating modes can helpto minimise noise.

8.8 Noise in perspective

For modern wind farm developments noiseconcerns need not be a serious issue if therelevant guidance is followed and where thereis a reasonable distance between properties andturbines. No landscape is completely quiet, andin most cases increasing aerodynamic noise willbe accompanied by increasing background noisefrom the wind itself. It is worth remembering

that the noise levels at conventional powerplants, and in their associated infrastructure andsupply needs, are likely to be far higher thanthose found at wind power sites and although itmay not be the same people affected – therewill be people that are.

However, developers have a responsibility toensure that noise assessments are completed toa high standard and mitigation measures put inplace where appropriate. The best advice forconcerned individuals is to visit an operational,modern wind farm and experience turbine noisein reality.

FURTHER INFORMATION

“The Assessment and Rating of Noise from Wind Farms” – report to the DTI -http://www.dti.gov.uk/energy/renewables/publications/noiseassessment.shtml

“Guidelines for Community Noise” – WHO -http://www.who.int/docstore/peh/noise/guidelines2.html

Health & Safety Executive noise information - www.hse.gov.uk/noise


9 Wind power and the community

Summary• The benefits of wind power are shared by the whole nation but it is local communities that are

most directly affected by wind farm developments

• Public attitudes to wind farms in the UK are generally positive and are evolving as more ofthem are built and as realisation of the need for renewable energy sources increases

• The involvement of the local community at all stages in the development of sites is key to thesuccess of the project

• Local communities may have a number of concerns when wind farms are proposed, includingimpacts on house prices and disturbance during construction; those concerns must be addressed

• There are many benefits to local communities from wind farms through rural regeneration,employment and other income

• Some communities create a local forum in order to ensure useful and fair distribution of thefinancial benefits

9.1 BackgroundWhile wind power can provide renewableenergy and environmental benefits on anational and global scale, it is the localcommunity that is most directly affected bythese types of development. When localobjections arise, development plans can bedelayed. Currently there are delayeddevelopments all across the UK, raising thepossibility that national renewable energytargets may not be met.

It is therefore essential that communities arefully consulted and involved when planning newwind developments so that their views can beheard. At the same time, it is important thatcommunities listen to the experience gained atprevious developments, and are aware of thepublic perception data that has been collected.This shows that in most cases the impacts ofwind developments are far less in reality thanpreviously feared, with the greatest support forwind found amongst those who live closest tothe turbines.

9.2 Public attitudesThe threats to everyday life in the UK andelsewhere caused by global warming andclimate change are beginning to be becometopics of popular discussion and public concern.Public attitudes to these threats in the UK andother European countries are evolving all thetime. Linked to this, support for wind farms inthe UK has been shown to be relatively stableover time.

Table 12 shows a summary of research over thepast 13 years into public attitudes towards windpower.



Location Sponsor/organiser Date Support Against No Opinion

UK

Britain

Scotland

Porthcawl, Wales

National Survey

South West

WatchfieldOxfordshire

Scotlandxxxiv

National Survey

Breckland District,Norfolk

Lambrigg WindfarmCumbriaxxxvi

Scotland

British Wind Energy Associationxxix

Poll by ICM for Greenpeace

MORI Social Research Institute surveyundertaken for Scottish Executivexxx

Greenpeacexxxi

Ipsos survey undertaken for theBritish Wind Energy Associationxxxii

MORI Social Research Institute surveyundertaken for SW Renewable EnergyAgencyxxxiii

Impact Assessment Unit, School ofPlanning, Oxford Brookes University

MORI Social Research Institute surveyundertaken for Scottish RenewablesForum

MORI Social Research Institute surveyundertaken for Greenpeace

Breckland District Council

National Wind Power (NWP)

Scottish Executive

Feb 2005

Sept. 2004

2003

2003

June 2003

March–April2003

May 2002

Sept.2002

2002

2002

April 2002

2000

79%

79%

82%

96%

74%

84%

84%

95%

72%

90%xxxv

74%

67%xxxvii

10%

8%

2%

4%

6%

4%

12%

2%

6%

9%

8

11%

11%

13%

-

-

20%

12%

4%

3

-

-

18

21%

xxix BWEA’s 'Wind Tracker' - a regular analysis of public opinion to wind energy in the UK. Conducted by NOP, 1000interviews, representative sample. (Figures are rising 74% in August 2004- 79% in Feb 2005).

xxx The survey was commissioned by the Scottish Executive to conduct survey research among people living close toScotland’s operational wind farms. The full report can be found at: www.scotland.gov.uk/publications

xxxi The poll was conducted by Greenpeace and 650 tourists visiting the towns beaches were interviewed. The vast majority(96%) said they would be just as likely or more likely to return to the resort if the turbines go up. Just 4% said theywould be less likely to return. www.greenpeace.org.uk

xxxii The survey was carried out by Ipsos amongst 2,624 UK household bill payers between 6th and 19th June 2003. 74% ofrespondents were supportive of the Government’s ambition to generate 20% of electricity from renewables by 2020,and a similar level of support was demonstrated for increasing the use of wind power in the UK (www.bwea.com).

xxxiii The survey (Public Attitudes Towards Renewable Energy in the South West), conducted across the south west by MORI,asked the question “To what extent, if at all, do you support or oppose the use of wind power in the south west ofEngland?” 54% Strongly supported; 30% tend to support; 12% neither support nor oppose; 3% tend to oppose; 1%strongly oppose and 1% don’t know.

xxxiv The survey, conducted in Argyll by MORI, found that 91% of respondents said the presence of wind farms would makeno difference to their decision to visit the area again. In fact 4% stated that they would be more likely to return (2%responded “less likely”).

xxxv Conducted by Breckland District Council 2002 to inform the development of SPG on Wind Energy. Respondents wereasked if the Council should support Wind energy (90.85% Yes, 9.15% No) and when asked what types of renewableenergy, 72.75% responded wind turbines.

xxxvi Survey of Residents and visitors to an area near the Lambrigg Wind Farm by National Wind Power.xxxvii This proportion increased to 73% for those living within 5 km of a windfarm.

Table 12: Summary of research conducted into attitudes to wind power



Despite these surveys it is clear that large-scaledevelopments have attracted vocal protests. Themost common complaints concern effects onscenery and landscape, turbine noise, theimpact on the local tourist industry, andpotential effects on property prices.

One report in particular, “Attitudes andKnowledge of Renewable Energy amongst theGeneral Public – Report of Findings”58, has someinteresting findings. As a UK-wide report, theresults are disaggregated to show the opiniontowards wind farms and wind energy in generalof different groups:

• Regional attitudes – In the UK as a wholeless than 2 in 10 people were resistant to thedevelopment of a wind farm in their area.People in Northern Ireland were more positivethan in any other area of the UK. People inWales were more resistant than any otherarea, with over 16% stating that they wouldbe strongly resistant to a wind farm in theirarea and a further 9% stating that they wouldbe slightly resistant.

• Knowledge of wind farms – Resistance toonshore wind farms was related toknowledge, with higher resistance foundamongst the less knowledgeable groups. This

Location Sponsor/organiser Date Support Against No Opinion

AVERAGE SUPPORT

AVERAGE LOCAL SUPPORT1992-2005

80%

80%

Novar, Scotland

Lynch Knoll, Glos

Bryn Titli, Wales

Coal Clough,Lancashire

Trysglwyn, Wales

Rhyd-y-Groes,Wales

Taff Ely, Wales

Kirkby Moor,Cumbria

Llandinam, Wales

Delabole, Cornwall

CemmaesWales

LlangwyryfonWales

NWP

Ecotricity, BWEA, Triodos Bank &Stroud DC

NWP (pre-construction)NWP (open day)

Liverpool University (dissertation)

NWP (open day)

BBC

BBC

National Wind Power (NWP)

CCWBBC

Dept. of Trade & Industry (DTI)

DTI

Countryside Council for Wales (CCW)

1998

1998

19961996

1996

1996

1994

1994

1994

1992/31994

1992/3

1992/3

1992/3

68%

67%

68%94%

96%

96%

61%

74%

82%

83%76%

84%

86%

78%

3%

7%

14%3%

4%

4%

32%

9%

9%

3%17%

4%

1%

8%

29%

14%

19%3%

-

-

7%

17%

9%

14%8%

11%

13%

14%

Table 12 (continued): Summary of research conducted into attitudes to wind power


indicates that in general the more peopleknow about wind power the more positivethey will be about a proposed development.

• Age groups – The age group of peopleresistant to onshore wind farms is similar tothose resistant to renewable energy ingeneral. They were more likely to be youngerrespondents aged 16-24 (18% resistance) andolder respondents aged 45+ (23% resistance)than those aged 25-34 (10% resistance) and35-44 (15% resistance). There was also aslightly higher resistance amongst thoserespondents who were retired.

• Benefits and disadvantages of wind farms –This report also collated the perceived benefitsand objections to wind farms. A summary ofthese is below:

Figure 17: Perceived benefits of onshore windfarms

As identified in Figure 17 over half ofrespondents see wind farms as being necessaryfor environmental or ‘greater good’ reasons. Butthe major objection to wind farms is the visualimpact (49%), followed by noise or hum at12%, and ‘not here’ responses at 10%.

Figure 18: Objections to onshore wind farms

European attitudesSome other European countries have a windenergy industry that is further developed thanthe UK’s. In a survey carried out across the EU-15member states in 2002, the opinions of 16,032people concerning energy and energytechnology issues were gathered59. This surveyrevealed that nearly nine out of ten peoplethought that global warming and climatechange were serious problems that requiredimmediate action. As far as energy policy wasconcerned, protection of the environment andlow prices for consumers were the top prioritiesfor EU citizens. The majority of people thoughtthat renewable sources of energy are the leastexpensive, the best for the environment and themost efficient.

Objections

■ Visual impact

■ "Not here"

■ Conditional

■ Noisy/hum

■ "Not enough space"

■ Dangerous

■ Other

49%

10%6%

12%

7%7%

9%

Perceived benefits

■ Environmental benefits

■ "Greater good"

■ "Nothing wrong with them"

■ Economic benefits

■ Conditional

■ Other

32%

18%35%

4%5%6%



In Europe – Germany, Spain and Denmark – inthat order, have the highest installed windpower capacity. Opinion polls in these countriesare not as detailed as those in the UK to datebut still give some indication of householderattitude:

Germany In the German state of Schleswig-Holsteinthe tourist board undertook a study to assessthe impacts of onshore and offshore winddevelopments on tourism. This studyconcluded that although visitors to the areaare aware of the increasing number ofturbines in the landscape they do notinfluence visitor behaviour.

A 2002 study by the Emnid Research Instituteasking “Would you welcome increased use ofwind power for climate protection reasons?”elicited a 92% ‘yes’ response from 1,003people questioned, which implies that eventhough there are considerably more windfarms in Germany, the majority of people arestill in favour of wind energy generation.

Spain Studies in Spain have showed 85% in favourof the implementation of wind power and1% against it60. Work in Albacete in 2002 forthe wind development company EEE showedthat 79% considered wind energy to be abenefit, with 1% believing it to be adisbenefit. Between 79% and 91% think thatthe benefits from wind energy compensatefor any negative effects on the environmentfrom installing it.

These studies suggest that Spain is similar toGermany in that although there isconsiderably more installed capacity than inthe UK the majority of people still favour it59.

Denmark A survey conducted by SONAR in 2001 showsthat support for wind power is very positive.The question asked was “should Denmarkcontinue to build wind turbines to increase

wind power’s share of the electricityproduction?” The answer ‘yes’ was given by68% of people. 18% found the current levelsatisfactory, 7% thought there were toomany and 7% were undecided.

These surveys in countries with many morewind farms indicate that UK public opinion,which is currently averaging 80% in favour ofwind power, is unlikely to change dramaticallyas the public become more familiar with them.However, continued monitoring of this situationis required.

9.3 Community concernsMany concerns that arise within communitiesare due to the perceived impacts on individualhouseholds, which have been discussed inearlier sections. The Scottish Executive’s study“Public Attitudes to Windfarms” researched theviews of local residents about winddevelopments in their area61. The followingissues were included:

• Visual impact

• Noise from turbines

• Interference with television and radio

• Environmental or ecological effects

• Impact on house prices and other localeconomic factors

• Disturbance during construction

• Consultation prior to construction

Most of these issues are covered in previoussections of this report, but the impact on houseprices and construction disturbance are discussedbelow.

House pricesSome local communities in the vicinity ofproposed wind farms are concerned that houseprices will drop if the development proceeds.



The Royal Institution of Chartered Surveyors(RICS) commented in a study on the housingmarket in November 2004:

‘The survey shows that 60% ofchartered surveyors with experienceof house transactions near to windfarms report that they negativelyaffect house prices, with most sayingthe biggest impact is at the time ofthe planning application. A smallernumber say that values dip the mostas construction starts, and fewer stillpoint to the moment where the plantbecomes operational. There isevidence that prices begin to recoverafter the wind farm has been up andrunning for two years. This suggeststhat wind farms become moreaccepted as communities grow usedto them.’62

This view is backup up by the Scottish Executivestudy, which suggests that anticipated problemswith house prices are not as serious in reality,with only 2% or so of residents reporting this asa problem after the wind project is operating.

Disturbance during construction andoperationConstruction activities that may disturb localresidents include increased noise and traffic.Both of these issues are normally limited tospecified working hours and days, in order torestrict the impact on nearby residents. Inaddition, the construction period in any givenarea is usually quite short.

The Scottish Executive study indicated that ofresidents who lived near to a wind projectconstruction site, only 6% said that there hadbeen problems with additional traffic and 4%said that there was noise or disturbance fromtraffic during construction.

Disturbances during the operational life of winddevelopments are usually limited tomaintenance activities. These activities wouldnormally involve a maintenance vehicle, andany required maintenance equipment. Mostinstallations have an annual cycle of operationalmaintenance.

9.4 Economic and communitybenefitsThe net economic benefits associated with thegrowth of the wind power industry are verydifficult to quantify, and such benefits may notalways occur close to the site being developed.Jobs will undoubtedly be created by the windindustry, in manufacturing, design, projectmanagement, site construction, and operation &maintenance, and in some areas theemployment contribution could be substantial.For example, the offshore wind sector isexpected to help ease the effect of the declineof the North Sea oil and gas industry oncommunities in Aberdeen and other port towns.The DTI estimates that up to 35,000 jobs couldbe created in the renewables sector by 2020, upfrom around 8,000 currently63, and a largepercentage of these are likely to be within thewind power industry.

However, some of the jobs created by the windpower industry will be at the expense of jobsthat would otherwise have occurred in othersectors, and any increase in electricity pricesmay also result in a small negative effect onemployment.



Case StudyCommunity Funds – Tappaghan, Northern Ireland

In March 2005, renewable energy company Airtricity completed its first Northern Ireland wind farmat Tappaghan Mountain in Co Fermanagh. The 13-turbine site is on the border with Co Tyrone and ismade up of the town lands of Glenarn, Stranahone and Stranadarriff. This has signalled thebeginning of the company’s £500m investment programme in NI renewable energy projects.

As part of the development Airtricity has createdthe Tappaghan Community Fund into which itwill pay £260,000 over the lifetime of theproject. The local community will benefit directlyfrom this new wind farm as £13,000 will beinvested in local community schemes in thearea each year.

The community fund model was establishedwith the Corneen Community Fund in 2001.Airtricity donates a fixed percentage ofrenewable energy income from its local windfarm operation to eight local projects. Whilegenerally supporting initiatives sustaining thelocal environment, other applications are alsowelcome. For instance, in 2003, grants wereawarded to Bawnboy Tidy Towns Committee,Templeport Irish Music Group and Kildallan GFC.

The cross community Tappaghan Community Fund will benefit from the development of the first wind farm in Northern Ireland.

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Case study: Community Funds – Tappaghan, Northern Ireland

“This project is a hugely significantdevelopment for Fermanagh. It willincrease Northern Ireland’s renewablegenerating capacity by about 20%and will make a valuable contributiontowards the target of ensuring that12% of all electricity consumed isprovided from indigenous renewablegeneration by 2012.”

Barry Gardin DETI Minister

“The community here at Tappaghanhas been very supportive of Airtricitythroughout this project and they canbe proud of the role they are playingin securing a sustainable energyfuture for Northern Ireland.”

Mark EnnisAirtricity Northern Ireland chief executive


• The focus on supporting targeted community needs and initiatives is readily replicable as a modelfor large-scale developers and energy companies in creating effective community engagement.Indeed, community funds have been set up on a number of wind developments throughout theUK.

• Community funds do not replace the need for effective public engagement on new wind farmdevelopments – they should be part of this process by encouraging dialogue between thecommunity and the developers.

Key facts:

• Airtricity submitted its first application in August 2002 to Planning Services in Northern Ireland forthe development of the Tappaghan Mountain 250ha open moorland site

• Planning approval was granted in November 2003. The 11-month project started in February 2004and involves 13 GE Wind 1.5 MW turbines with a hub height of 52.6m and a rotor blade diameterof 70.5m.

• The wind farm at Tappaghan will have a capacity 19.5 MW and will provide enough electricity for57% of the domestic demand of the population of Fermanagh District Council.

• For more information: www.airtricity.com


Case StudyCommunity Ownership – Isle of Gigha, Scotland

After many years of decline, the Isle of Gigha’sprivate owners, the Holt family, put it up forsale in August 2001. After a democratic votethe 98 strong population (including sixchildren) decided to launch a bid to buy theisland, supported by the local MSP and anumber of other bodies. The community set upthe Gigha Heritage Trust, which became thenew owner of the island on March 15th 2002.

A condition of the grant was to pay back £1million of the grant to the Scottish Land Fund byMarch 2004. The Board of Directors of the GighaHeritage Trust established a five-yeardevelopment plan to regenerate the islandincluding plans for sustainable housing, theGigha Hotel, holiday cottages and a wind farm.After a year of feasibility studies, tests andplanning assessments, work started in November2004 with stone for the road and foundationsbeing excavated from the new Gigha Quarry. Thesecond-hand ‘ Dancing Ladies’ named by thecommunity as Faith, Hope and Charity weredelivered at the end of November, cleaned up bymembers of the community, erected, and on15th December 2004 were switched on.

The Gigha community now generates two thirdsof its electricity requirements and is using part ofthe money generated by the wind farm tocontribute to radical energy saving measures inthe trust-owned housing stock, 80% of which isbelow a reasonable standard.

“The wind resource in Scotland is unparalleled and more communities should beable to tap into this. Gigha was able to capitalise on the available wind due to acombination of a unique financial package and the willingness andentrepreneurship of the community themselves.”

Dr Eleanor LoganChief Executive, Isle of Gigha Heritage Trust

Brandon Clements, Rhona Earnshaw and Phoebe Brownturn on the Isle of Gigha ‘Dancing Ladies’ providing the130 strong community with energy and independence.

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Case study: Community Ownership – Isle of Gigha, Scotland


• Community ownership offers a highlyinclusive model for wind farm developmentthat can be replicated in many parts of theUK.

• By generating their own electricity andselling their Renewable ObligationCertificates through their electricity supplier,Gigha residents will generate a new sourceof revenue for the island, whilst providingfunds for the replacement of the turbines atthe end of their working life.

• The residents are using the net profit fromthe project to fund energy efficiencyimprovements, which should in time allowthe community to reduce their energyconsumption and achieve an even highercontribution from renewable energy withoutany expansion in generating capacity. Indeed,one day they could become net exporters.

Key facts:

• The Isle of Gigha is the most southerly ofthe Hebridean islands, three miles west ofthe Kintyre Peninsula. Population is 130 andrising with 15 children in the school.

• The project used three pre-commissioned(second hand), Vestas V27 wind turbineswith a rated capacity of 225 KW. Theturbines were originally installed atWindcluster’s Haverigg 1 site in Cumbria,which was recently ‘re-powered’ (upgraded).

• Total capital expenditure was £440K, basedon a three-way mix of grant funding, debtfinance, and equity finance. The projectanticipates gross annual income of £150K.

• Further information can be found at:www.gigha.org.uk/windmills

• Several other community projects exist inthe UK, see the following links for furtherinformation: www.energy4all.co.uk;www.baywind.co.uk; www.reic.co.uk.

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If local jobs are created around a wind turbinedevelopment, they are likey to be in site-construction as well as operation andmaintenance. Wind power developments alsohave the potential to increase rural incomesthrough rents on land leased to winddevelopers.

Wind projects can also bring economic benefitsto a community through community benefitpayments or the development of a communitytrust. Community benefit payments arevoluntary payments from the developer to thecommunity based on the projected electricaloutput of the wind farm.

Community trusts or co-operatives enablemembers to invest their savings in a winddevelopment. The profits of the scheme arethen shared amongst those belonging to thetrust, usually in the form of regular dividends.One of the most successful examples is theBaywind Energy Co-operative Ltd in Cumbria.

Some developers prefer to help communities inother ways, such as:

• Site conservation and habitat creation forprotected flora and fauna

• Improved footpath and site access

• Job creation for site management andconservation initiatives

• Improved TV reception for rural communities

• Educational programmes for local schools

• Grant funding to support local energyefficiency schemes

9.5 Public consultation

What is public consultation?Public consultation usually occurs during theplanning and development of the wind farm as

part of the preparation of the EnvironmentalStatement (from the EIA) and then once aformal application has been made to therelevant planning authority. This wouldconstitute good practice on behalf of thedeveloper.

Legally, the public must be consulted followingthe submission of a planning application to thelocal authority for a proposed wind farmdevelopment. This is the only stage at whichthere is a legal obligation for the public to beconsulted. The developer would normally placean advertisement in a local paper to advertisethe scheme and invite comments. The planningauthority of the local council may also advertisethe application in the local press or on thecouncil’s planning website. Some people mayhave been contacted prior to this stage if theyare neighbours of the scheme or if theEnvironmental Impact Assessment processindicated that they may be negatively affectedby the scheme.

Good practice in public consultation Good practice in public consultation wouldinvolve the public at an early stage. Pre-planning public consultation can yield benefitsfor both the developer and the public. Thedeveloper will gain a valuable insight into theissues of local concern and can plan thedevelopment of the scheme to mitigate anynegative impacts at an early stage. The publicbenefits as it gives them time to becomeinformed about the scheme and much moretime to prepare a response to the proposal. Theconsultation process may involve manystakeholders, including the developer,landowners, NGOs, regulatory authorities, localcommunities, neighbouring property owners andanyone or any organisation that may beaffected by the development in either a positiveor negative way.



Local communities could be consulted by thedeveloper, the local planning authority or by anindependent third party working on behalf ofthe developer. A Scottish study published in200360 asked a number of questions aboutpublic consultation, which revealed that veryfew people can remember being consulted overthe development at the planning stage (13%).The most common source of information aboutthe proposed site at that time was the localnewspaper (40%) rather than the local councilplanning office (4%) or the developer (1%).However, few are dissatisfied with theconsultation by the developer (11%), with mostexpressing neutral views. Views are broadlysimilar with respect to the consultation from thelocal authority, although even fewer canremember being involved in this.

If there is to be greater dialogue during aplanning proposal, communities usually like tosee it publicised through their local paper(43%), leaflets through the door (33%) orthrough public meetings (29%).

Formal consultationOnce planning permission is applied for, theEnvironmental Statement will be made availableto the public for viewing. In addition, developerswill often hold information sessions in order toanswer any specific questions that thecommunity may have.

As wind farms become more common aroundthe world, their potential impacts will be furtherresearched and documented. Numerous bestpractice documents exist that developers canuse in designing their wind farms to minimisetheir impact on the local environment and to

benefit the surrounding community. A selectionrelevant to the UK include:

• British Wind Energy Association (BWEA)(1994). Best Practice Guidelines for WindEnergy Development. Londonxxxviii.

• Carroll, B. and Turpin, T. (2002). EnvironmentalImpact Assessment Handbook: A practicalguide for planners, developers andcommunities. Thomas Telford Publishing Ltd.,London.

• English Nature et al. (2001). Wind farmdevelopment and nature conservation. EnglishNature, Peterborough.

• SNH (2001). Guidelines on the EnvironmentalImpact of Windfarms and Small ScaleHydroelectric Schemes, Scottish NaturalHeritage, Perth.

Some principles for good public consultation aregiven in Box 7, followed by wind farm specificguidelines as promoted by the South WestRenewable Energy Agency – see Box 8.


xxxviii Currently being updated.


Case StudyCommunity Engagement – Moel Moelogan, North Wales

Moel Moelogan wind farm officially opened on31st January 2003 as the first 100% communityowned project of its kind, run by a collective ofthree farmers in Conwy County, North Wales.Their aim was to develop wind power whileretaining the economic benefit locally.

In 1997, sheep and livestock farmers, RobinWilliams with 700 acres, his brother RheinalltWilliams with 600 acres and neighbour GeraintDavies with 430 adjacent acres, faced a declineof up to 75% in their farming incomes followingthe BSE crisis. The three formed the CwmniGwynt Teg cooperative in 1998 to enter thewind energy industry.

Around 1500 people attended an open daywhen the first turbine was erected in September2002, and on January 31st 2003 some 500 localsattended a public exhibition of the extensiongiving a 100% positive response. Objectionsraised later led to significant changes, includingreducing the turbine height from 60 metres to50 metres and four major changes of position.

The finance model for the project was providedby a £1.7 million loan from Triodos Bank, anObjective One grant of £366,000 from theEuropean Union and a commercial loan of£460,000. Turbine technology had advanced sorapidly between the time of writing theapplication and receiving planning permissionthat the farmers realised they only needed twoturbines to fulfil their contract with the NFPA.Planning permission for the third turbine wassold to German company, Energie Kontor, toraise equity.

Having gone to the local community forresponses to the two operational turbines fromJanuary 2003, the collective was grantedplanning approval on 26th November 2004 fortheir second wind project Ail Wynt - whichtranslates as 'Second Wind '- for a further nineturbines on the hills near Llanrwst.

Conwy County Borough Council PlanningCommittee logged all forms of first and secondstage consultation process representation for AilWynt in November 2004 including letters, pro-forma letters and a petition regarding the secondphase. There were 428 letters of support, 85% ofthese in favour of clean/cheap/safe renewableenergy. Of the 234 letters of objection, 63%focused on phase 2 being ugly and damagingthe views and landscape. The Committeegathered expert views from the CountrysideCouncil of Wales and Snowdonia National ParkAuthority to show this would not be significant‘in this particular case’.

”You have to have local consultation. You get planning ups and downs and localopposition groups who will say that the main issue it visual and that turbinesare spoiling the countryside. But I think the countryside evolves and has beenconstantly changed by the people who live and work on the land.”

Geraint DaviesCo-founder Cwmni Gwynt Teg cooperative

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Case study: Community Engagement – Moel Moelogan, North Wales

The cooperative hopes to raise £1 milliontowards project costs by offering the localcommunity an opportunity to invest in Phase 2through a bond issue offering an estimated 8%per annum return on capital, with bonuspayments in windy years. The remainder of theproject costs will be covered by commercialbank loans and the cooperative's own resources.Ail Wynt has committed to donating £50,000 ayear to an energy savings grant scheme to helplocal families and schools save energy and£15,000 a year to two local councils to supportother local initiatives.

Cwmni Gwynt Teg won the prestigious AshdenAwards for Sustainable Energy in June 2003. Amajor factor was being sensitive towardscommunity and environmental issues.


• Coming from within the community, thiswind farm development represents one ofa number of community ownership models.

• This new source of income can help tosupport sustainable rural developmentwithout displacing traditional rural activities– sheep farming continues alongside theturbines.

• The main opposition was based on landscapechange, but the level of objections on bothsides shows how subjective an issue this is.

Key facts:

• The two Moel Moelogan turbines areconnected to the national grid via asubstation at Llanrwst, 4.5km away fromthe wind farm. A grid connection wasconstructed by the local power distributioncompany, Manweb (owned byScottishPower). The connection cost £690K -almost 25% of the budget.

• Each of Moel Moelogan’s turbines is ratedat 1.3MW.

• The cooperative has a working relationshipwith the Royal Society for the Protection ofBirds (RSPB) to manage approximately 300acres of land on their farms to encouragethe breeding of endangered species likelapwings and golden plover.

• For further information: www.ailwynt.co.uk,www.ashdenawards.org

“In balancing sustainable energy production against landscape (and otherfactors) it is appropriate to follow a reasoned and logical approach… it isconsidered that the Moel Moelogan site provides a less sensitive developmentsite for wind turbines than other potential prospects for a similar scale scheme.”

Conwy County Borough Council Planning Committee conclusion point 60

Three hill farming families initiated the development ofwind energy consulting with and benefiting their localNorth Wales community.

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Principles of Effective Public Consultation

The Environment Council recommends that the following principles will help to ensure that publicconsultation is effective whatever form of engagement with the public is used.

InclusivenessAll stakeholders should be encouraged to become involved. A particular effort should be made toinclude the unaffiliated, minorities, the marginalized and the ‘silent majority’.

Transparency, Openness and ClarityAll stakeholders should receive all of the information they need. If information is lacking or thingsare uncertain they should be informed. It should be made clear what stakeholders can or cannotinfluence by contributing.

IndependenceIn highly polarised or contentious situations a neutral convenor and independent facilitator should beused to gain the confidence of the stakeholders. It is not possible for a sponsoring organisation,whether the local authority or private company, to facilitate an independent process and any attemptto do so will arouse suspicions about the integrity of the process.

CommitmentRespect for stakeholders is demonstrated by giving the public consultation process the priority andresources that it deserves.

AccessibilityDifferent ways for people to become involved are important. The UK has a diverse multiculturalsociety and it is essential that people from all parts of the community are able to participate.

AccountabilityAs soon as possible following the consultation period, participants should be contacted with anaccount of how and why their contributions have (or have not) influenced the outcome.

ResourcingA good public consultation requires time and money, a lack of resources can undermineachievements.

ProductivityThe aim of public consultation is to improve the outcome for all concerned. How the consultationprocess will achieve this should be made clear from the beginning to prevent any waste of time andresources.

Box 7: Environment Council’s public consultation guidelines

Local authorities are statutorily obliged to consult their communities on development proposals,nevertheless the following guidelines can be helpful:



The South West Public Engagement Protocol and Guidance for Wind Energy64

This guidance document was commissioned by the South West Renewable Energy Agency andoutlines a series of responsibilities aimed at local planning authorities and wind energy developersfor promoting more effective public engagement within the development of wind energy projects.The protocol also covers the responsibilities that should be met by stakeholders to ensure theprotocol works effectively. It is the only guidance document of its kind in the UK.

Wind energy developers agree to:

• Prepare and apply a coherent engagement plan in discussion with the local planning authority,which will include:

– Identification of relevant stakeholders– Agreed timescales for turning around key phases of the planning process and responding to

information requests– Identification of a clear point of contact that will enable a two way flow of information

regarding the project– Identification of the range of methods appropriate for engaging the relevant stakeholders– Clarifying the approach to establishing local and wider benefits

• Promote at an early stage the scope of the consultation, the outline plans for the development,company policy on local benefits and opportunities for public participation

• Identify at an early stage and consult on the potential for local benefits

• Ensure any changes in the engagement plan, in particular changes in timescales, arecommunicated to other stakeholders in good time

• Ensure participants are kept up to date on progress and feedback is made available on the resultsof engagement and how it is being used within the development of the project

Local planning authorities agree to:

• Prepare and apply clear planning policy and guidance on wind energy in accordance with nationaland regional policy and guidance and in consultation with neighbouring local planning authorities

• Support the evolution of the developer’s engagement plan by:– Establishing a clear point of contact that will enable a two way flow of information regarding

the project– Agreeing timescales for turning around key phases of the planning process and responding to

information requests (any variation from statutory timescales should be clearly justified)– Supporting the identification of key stakeholders and the methods appropriate for engaging

them– Contributing to discussions on the approach to establishing local and wider benefits

• Provide support in communicating with key stakeholders and help in identifying the full range ofcommunity views

Box 8: South West Renewable Energy Agency’s public consultation guidance



• Ensure the sourcing of objective information on disputed areas of debate that is reliable andindependent

• Ensure elected members are fully up to date on general issues relating to wind energy technologyand the implications for planning

• Provide a high quality flow of information within the authority on proposed developments,including regular briefings for members and other relevant local authority officers

Other key stakeholders will be expected to:• Enter into constructive dialogue with a view to working towards agreed positions on issues up for

negotiation

• Acknowledge developer and/or local planning authority responses to questions and criticismsraised by other stakeholders

• Assist, where possible, in identifying other key stakeholders within the community

• Assist, where appropriate, in identifying the full range of local opinion about the development oflocal benefits

• Encourage the identification of points of contact that will facilitate a high quality flow ofinformation within the community

Box 8 (continued): South West Renewable Energy Agency’s public consultation guidance

9.6 Lessons for successPrevious wind farm developments have shownthat success lies with early communityconsultation, involvement and empowerment.With the introduction of updated planningpolicies for renewable energy there is increasedemphasis on the need for communityinvolvement early on in the process.

Local planning authorities, regional stakeholdersand Local Strategic Partnerships should fostercommunity involvement in renewable energyprojects and seek to promote knowledge of, andgreater acceptance by, the public of prospectiverenewable energy developments that areappropriately located. Developers of renewableenergy projects should engage in activeconsultation and discussion with localcommunities at an early stage in the planningprocess. Communities should be aware of good

practice elsewhere in the UK where beneficialarrangements have been agreed for theircommunity, and where impacts on the localenvironment have been successfully mitigated.

The involvement of the local community isessential in ensuring that all aspects of publicconcern are understood and taken into accountin the design of the site. Codes of practice withexamples of good practice are readily availablethat give guidance on how to address thevarious technical and perception issues of publicconcern. The planning system providessafeguards and opportunities for publicparticipation and for developers to contribute tocommunity welfare through a variety ofmechanisms.


10 Aviation and radar

Summary• Wind turbines can present a hazard to low flying aircraft and may also affect radar and radio

navigation systems

• Early consultation with all statutory authorities can help successful siting and mitigationdecisions to be made

• Planning systems are in place to regulate the development of tall structures and a pre-application approval system has been established for wind developers

• International experience suggests the UK has some of the strictest policies in place on radar andaviation – these must be justified

10.1 BackgroundAviation and radar issues are complex andoverlapping, and have long been a major sourceof complaint for the wind industry. This isbecause wind turbines can have negativeimpacts on radar systems and can representobstructions for low-flying aircraft, and theseconcerns have resulted in a significant numberof planning objections, particularly from theMinistry of Defence (MOD). For their part, theMOD, the Civil Aviation Authority (CAA) andNational Air Traffic Services (NATS) have astatutory duty to safeguard certain sites andairspace from radar interference in the interestsof national security and for the safe operation ofpassenger and military aviation – this duty wasrestated in the 2003 Energy White Paper46.Individual airports can also be affected by winddevelopments.

Planning applications were in the pastfrequently rejected on the basis of risk toaviation and radar, but the MOD now advisesdevelopers on acceptable areas from theirperspective well in advance of a formal planningapplication. Aviation and radar concerns arerarely clear-cut, and solutions can often befound to specific problems where there is a willand where good channels of communicationexist. To forward this aim, the DTI establishedthe Wind Energy, Defence and Civil Aviation

Working Group in 2001 to bring together all thestakeholders with the specific objective ofimproving the understanding of the interactionbetween wind farms and the aviationcommunity, developing suitable mitigationtechniques and improving the pre-planningconsultation process. This group published WindEnergy and Aviation Guidelines in 2002 andthese will be updated and republished towardsthe end of 2005.

This section will explain the issues related toaviation and radar including current policy,international experience and possible futuredevelopments. Further technical details areavailable in Annex C.

10.2 Radar

Types of radar Radar takes two basic forms. Primarysurveillance radar (PSR) usually consists of anantenna constantly rotating through 360º roundthe horizon, sending out pulses ofelectromagnetic energy, which result inreflections that are displayed on a controller'sscreen. Secondary surveillance radar (SSR) alsosends out pulses from a constantly rotatingantenna but in the form of interrogation signals,which trigger responses from transponderequipment in aircraft.


Effects on PSRThe main effect of wind turbines on PSR is dueto the rotation of the blades. Since the bladesare rotating, they may not produce a radarreturn on every sweep of the radar, and inmultiple-turbine wind developments, the radarmay illuminate one turbine on one sweep, thena different one on the next sweep, and so on.This can produce shifting radar returns fromwithin the wind site, sometimes referred to as a'twinkling' appearance on the radar screen. Inmost cases, these effects only occur when thewind development is within line of sight of theradarxxxix.

There are three uses for PSR in aviation: for airtraffic control (ATC) around airfields, for area or'en route' ATC, and for military air defence.

ATC around airfieldsMost military airfields and commercial airportsare equipped with PSR, which is used bycontrollers to guide aircraft after take-off, toguide incoming aircraft to the runway, and tomaintain separation for aircraft operating in thevicinity of the airfield. For these radar systems,a wind development located beneath thedeparture track, or the final approach track cancreate particular problems.

For military airfield radars, the MOD requestsconsultation on projects within 36nm (67km).Whilst controllers may guide aircraft onestablished tracks, aircrew regularly require todeviate from these tracks due to the nature ofthe military task. Therefore, an objection islikely for any wind energy project within 36nmwhich is determined to be visible to the radar.Unlike civil aircraft, military air movements are

not confined to defined routes therefore fullview of airspace is required for air traffic control.

En route ATCControl of aircraft in the en route phase of flightis carried out using a network of long-rangeradars, located mostly on hilltops stretchingfrom Devon to Shetland and operated by NATS.Most of these aircraft are flying in controlledairspace and have SSR transponders, so inprinciple these radars are not as vulnerable tothe effects on PSR outlined above. Howeverprimary radar returns from a wind developmentlocated underneath a busy airway may clutterthe screen and make it more difficult forcontrollers to differentiate their traffic from theclutter.

NATS en route radars are a frequent source ofobjections to wind developments in the UK dueto their generally prominent positions and theirlong range. However, despite the large numberof projects receiving initial holding objections, asignificant number are subsequently determinedto have little or no significance for ATCoperations.

Air defence radarThe MOD safeguards seven air defence radarsites around the UK coastline. The air defenceradars are at the heart of an air surveillancesystem which aims to provide unbrokencoverage of UK airspace to enable the detection,tracking and identification of all aircraftmovements down to the lowest practicablealtitude and to deny a clandestine air approachto the UK mainland.

The Government perceives an increased risk ofinternational terrorism and as such air defence


xxxix Certain weather conditions may bend radar energy over the horizon on an irregular basis.


has assumed a higher priority. Air defence radarpolicy is under continuous review in the light ofemerging research and studies and is steadilymoving towards a risk based assessment ofindividual proposals.

The MOD’s current policy is to raise concerns toany proposed wind project within line of sight ofan air defence radar head. However, riskassessments are completed on all pre-planningproposals where developers requestconsultations through Defence Estates. In theinstance that the additional risk to air defenceoperations and training is assessed asmanageable, the concerns are removed. MODpolicy remains under constant review in light ofemerging research and study work – the nextformal policy review will be undertaken in July2005.

Effects on SSRSSR is much less vulnerable to interference fromwind turbines than PSR. The main potentialeffects are multi-path, where some of the radarenergy travels from radar to aircraft (or viceversa) via a reflection off a wind turbine. Studieshave found that wind turbine effects on SSR arenegligible for a wind development located 5kmor more from an SSR station. In the UK, thereare statutory consultation requirements for anywind project within 10km of any SSR facilities.

10.3 AviationCurrent plans envisage a rapid, andfundamentally unsustainablexl, increase inaviation over the coming decades, with thepotential to increase conflicts between aviationinterests and the development of wind energyas new airports are developed and existing onesexpanded. The most significant impact of windturbines on aviation is from radar interference,

but the physical obstruction hazard to aircraftnear airports and in military low flying areas hasalso generated concerns. Radio navigation aidsmay also be affected.

The UK is party to international agreementswhich set limits to the height of anyconstructions within specified distances ofairfields, in order to prevent obstacle hazards toaircraft using that airfield. Broadly, winddevelopments within 10km of airfields are likelyto come into conflict with these regulations,while the restrictions are unlikely to apply toprojects beyond 15km from an airfield. The CAAare responsible for safeguarding commercialaviation interests.

Wind turbines can present a collision hazard tomilitary aircraft engaged in low flying training,which under normal circumstances would beeasily overcome by flying around or over them.However, wind turbines in some locationspresent an increased hazard to the safety of lowflying military aircraft due to airspace andgeographical constraints, proximity of otherobstructions and weather factors. Low flyingtraining, which is conducted by fast jet aircraftdown to 30m above ground level and largefixed wing aircraft down to 45m above groundlevel, is only permitted in three parts of the UK:part of northern Scotland, south-west Scotland &northern England, and central Wales. Althoughmuch of this training is conducted overseas, theMOD considers it essential that the three UKareas are retained to maintain the requisitedomestic military capability. In line with currentMOD policy, all potential wind farmdevelopments are assessed on a case-by-casebasis and it is usually possible to accommodatemost proposals with varying degrees ofalteration. Developments located on ridges orthe higher hilltops (the best sites for wind


xl SDC(2004): Missed Opportunity: Summary Critique of the Air Transport White Paper, London.


turbines) are more likely to be acceptablebecause low flying training is concentrated morein the valleys and gently undulating terrain.

The greatest hazard posed by wind turbines tomilitary low flying training is in the vicinity ofthe Spadeadam Electronic Warfare and TacticsRange (EWTR) on the Cumbria-Northumberlandborder. Most types of military aircraft conducttactical flying training in the EWTR that cannotbe achieved elsewhere in Europe. For thistraining to be effective, aircraft need to be ableto fly at very low level (ground level in the caseof helicopters) with complete freedom tomanoeuvre. Moreover, the radar systems usedin creating a tactical environment need to beable to operate with minimal interference. Theimplication is that proposed wind developmentsin the EWTR area are unlikely to be accepted bythe MOD.

10.4 Seismic stationsAlthough not strictly a radar or aviation issue,seismic monitoring has recently become asignificant constraint on wind energydevelopment in the important area of southernScotland and northern England. This is due to aseismic monitoring station in Scotland which isused to monitor international compliance withthe Comprehensive Test Ban Treaty (CTBT),among other activities. There are concerns overthe generation of seismic vibration from windturbines which can mask the seismic signalsfrom nuclear weapons tests.

To address this problem the MOD, in partnershipwith the BWEA and DTI, commissioned researchto look into this issue. They found that windturbines of current design could interfere withthe operation of the station, but a way forwardhas been agreed by setting a ‘noise limit’

(0.336nm rms), which is effectively double theexisting noise level at the site. The noise limitextends to 50km around the site, and proposalsfor wind farm schemes beyond the 50km zonewill be assessed against any remaining noiseallocation budget. In principle the further aproject is away from the seismic recordingstation the less the potential interference. Iffuture wind turbine designs can be shown toeffectively stop the generation of seismicinterference then the policy will be reviewed.

10.5 Regulatory processDefence Estates (responsible for safeguarding atthe MOD), the CAA and NATS act as focal pointsfor wind farm developers to consult withdefence and civil aviation interests. DefenceEstates operates a statutory safeguarding systemto ensure that the operators of key civil andmilitary aerodromes, radar stations andnavigation facilities have the opportunity toevaluate potential impacts from developmentsin their vicinity at planning application stage.

Because impacts on aviation and radar arepotentially serious enough to prevent approval ofa wind project, developers would be takingunacceptable risks with their investment if theydid not evaluate these effects well beforecommitting to a planning application. DefenceEstates therefore offers a pre-planning assessmentservice for potential wind developments on behalfof all three organisations, with a helpline numberxl

for preliminary enquiries. This takes a number ofstages:

1. Developers can use a series of high-resolution maps developed by NATS todetermine whether their proposed site islikely to be in a problem zone for en-routeATCxlii.


xli Further information is available from the BWEA website at www.bwea.com/aviation xlii The MOD are currently developing mapping tools for their radar sites.


2. They can then submit their proposal using astandard proforma to Defence Estates for amore detailed analysis. Their proposal iscirculated to a number of relevant agenciesxliii

and experts by Defence Estates to determineits likely status: ‘no concerns’, ‘possibleconcerns’, or ‘serious concerns’.

3. If any issues have been raised, the developercan then ask to discuss possible mitigationmeasures or technical solutions throughDefence Estates.

4. Using the advice obtained, the developer canthen decide whether to seek formal planningpermission. Defence Estates will use theirfinal assessment as the basis of theirrecommendation to the planning committee.

Out of the 4,000 pre-planning requests receivedsince 1996, around 2,000 received ‘noobjections’ advice. There are currently plans tospeed up this process through the introductionof a web-based pre-planning submission serviceand Defence Estates aim to reduce the replyperiod to less than seven weeks.

10.6 International experienceOther countries in Europe have had a generallydifferent experience of the relationship betweenwind turbines and air traffic control or airdefence radar. A report commissioned by the DTIWorking Group on Wind Energy, Defence andCivil Aviation Interests in 2002 found that onlythe German Ministry of Defence had a formalsafeguarding consultation zone around its radarssimilar to the system in the UK, and that "allother countries have a much more relaxedattitude to the potential impacts of windturbines on radar-dependant operations andassess proposals on a case-by-case basis."65

In the Netherlands, several wind farms havebeen built in the vicinity of its busiest civilairport, Amsterdam Schiphol, in the past fewyears. These include a 14-turbine developmentin the Amsterdam Western Harbour, 10km northof Schiphol, and under the final approach pathto one of its runways, a four-turbine wind farm15km away at Haarlem, five turbines at Velsen,20km NW of the airport and ten 100m turbinesat Flevoland, 25km east of Schiphol. Althoughsome of these had been erected withoutfollowing the established consultation processwith the Dutch air traffic control authority, LVNL,none of the wind farms subsequently appearedon the airport's radar. LVNL believes this is dueto processing originally applied in the radar toeliminate spurious returns from road traffic.

Denmark has the most extensive experience ofwind turbines operating within line of sight ofradars. In late 2001 the country had more than1,800 wind turbines located within 30km of airtraffic control radars and over 500 within 30kmof air defence radars. Many of these turbines aresmall single units but due to the predominantlyflat terrain, radar visibility is generally good.Other than at Copenhagen Kastrup Airport, theDanish experience has been that wind turbinesdo not adversely impact air traffic and airdefence radar operations.

Kastrup has 71 wind turbines within 30km,including eight located only 2km from theairport's SSR and 4km from its main primaryradar, and a major 20-turbine offshore windfarm at Middelgrunden, 7-10km north of theairport. The Middelgrunden turbines lie directlyunder several instrument approach procedures.On commissioning, it was found to generateprimary radar clutter and SSR false plots,although in each case the effects were not as


xliii These include CAA, NATs, and Ofcom, who are consulted over possible telecommunications disruption – see following section.


severe as those caused by existing road traffic,chimneys, and buildings around the airport. Inrelation to the primary radar clutter, the trackprocessing applied in the airport's radarsuccessfully mitigated the effects, while the SSRfalse plots were dealt with using a proprietaryEurocontrol software tool.

The Dutch and Danish experience illustrates thepotential for regulatory policy and air trafficcontrol experience to accommodate windturbines in proximity to radars. However, thedifferent experience from the UK is explained inpart by differences in the structure of airspaceand the way in which it is managed. Thesedifferences include:

• The UK has more extensive uncontrolledairspace within which wind turbines have agreater potential impact

• The Danish and Dutch ATC authorities routinelycontrol en route traffic using SSR only

• Due to uncertainties about its ability to displaynon co-operating aircraft, the UK CAA does notpermit reliance on the type of track processingsoftware used in Denmark and theNetherlands.

There is also growing experience of co-existenceof wind turbines and radar in the USA. At PalmSprings in California, clutter problems on anolder generation primary radar which hasaround one thousand wind turbines within itscoverage were addressed by the installation of anew solid-state radar in 2001. The new radarhas been able to provide a full radar service toaircraft crossing the wind farm area. Howeversubsequent investigation found that, in practice,the service over the wind farm area was beingprovided using SSR only. This would not beacceptable to the regulatory authorities in theUK due to the policy that in normalcircumstances an aircraft's radar identity mustbe confirmed and maintained using at least

primary, and, where available, primary andsecondary radar. Routine controlling using SSRonly is only permitted in certain less busy partsof the upper airspace where proceduralseparation between aircraft can be applied inthe event of radar failure.

10.7 Mitigation measuresA number of mitigation measures are availablethat could reduce the conflicts between winddevelopments and aviation/radar concerns:

Operational measures

• Increasing controlled airspace

• Avoiding areas of significant air traffic controlinterest

• Introduction of Mode S secondary surveillanceradar

• Limiting radar service in uncontrolled airspace

Technical measures

• Range-azimuth gate mapping (RAG mapping)

• Temporal threshold processing

• Clutter maps

• Track processing

• Placing antennae at an elevation that raisesthe radar beam above the wind farm

• A number of technical design improvements,such as radar absorption by turbine blades

Further details on some of these measures canbe found in Annex C. The DTI-funded AMSFeasibility Study (due to be published in June2005) aims to specifically identify and evaluatetechnical software and hardware mitigationtechniques which will then be assessed by theMOD.




10.8 Balancing prioritiesIn general, many aviation and radar issues canbe resolved, firstly by good site scoping, andsecondly through a number of technicalsolutions that are either site-specific or morewide-ranging. The message for developers isthat early consultation with the key regulatorystakeholders is essential, and can often avoidproblems later on.

Safeguarding institutions also have a role to playin seeking to minimise objections to wind powerdevelopments and in trying to find solutions toproblems wherever possible. In some cases

there may be issues over who is to pay for anyidentified measures, such as in the case ofadditional radar stations, which can beexpensive. Such issues should not present abarrier to large or important projects goingahead. Considering the relative flexibility ofarrangements in other European countries, theGovernment should be able to justify allmeasures currently in place, and should aim tokeep abreast of international developments inthis field so that good practice and the latesttechnological solutions can be used.

FURTHER INFORMATION

Wind Energy and Aviation Interests (Guidelines and Proforma) – DTI -www.dti.gov.uk/renewables/publications/pdfs/windwnergyaviation.pdf


11 Telecommunications

Summary• Wind turbines can interfere with radio signals and effect TV reception and telecommunications

systems

• However, a number of solutions are available to developers to counter any negative effects andthese should be identified early so that mitigation measures are included in the consentsprocess

11.1 BackgroundTelecommunications signals (including TV, radioand data/voice transmission) can be negativelyaffected by wind turbines. The main issue is themulti-path effect, where there is corruption ordistortion of the received signal. Multi-patheffect can be caused by any object capable ofreflecting radio waves. This may includebuildings, towers and other stationary objects.

The effect of wind developments ontelecommunications fall into two maincategories: effects on broadcast television (andits supporting transmission network), and effectson fixed radio links, mostly at microwavefrequencies. Technological trends are changingthe telecommunications environment, whichbenefits wind energy development.

The Office of Communications (Ofcom) hasresponsibilities for licensing telecommunicationssystems and protecting radio systems againstinterference. It also plays an important role inthe pre-planning consultation process, providinginformation on potentially affectedtelecommunications facilities in the vicinity ofproposed wind farm developments.

11.2 TelevisionTelevision signals are broadcast from a networkof main transmitters around the country,supplemented by additional, lower power, localtransmitters in areas where the main signal is ofpoor quality. Broadcast transmissions are

vulnerable to multi-path effects in the sameway as any radio signal, leading to 'ghosting' onthe TV picture.

Wind turbine impacts on television receptionquality are generally only found where thetelevision subscribers are located in an areawhere they have a wind farm between themand their nearest TV transmitter. To overcome TVtransmission interference the following can bedone:

• A more sensitive receiver antenna could beprovided for affected householders

• Antennae could be moved to receive from adifferent source transmitter

• A local community re-broadcast facility couldbe installed

• Alternative means of transmission, such assatellite or cable, could be used by affectedhouseholders

In the future, the switch from analogue todigital terrestrial television may mean thattransmission networks become less vulnerableto interference from wind developments.Communities should negotiate with developersearly on in the development process to be surethat they do not suffer negative consequenceswhen the wind farm is operational and thatappropriate mitigation measures are planned. Itshould be noted that any large or talldevelopment could interfere with televisionreception, including the chimneys of local power


11 Telecommunications

plants. Therefore, this problem is not specific towind power, and solutions are well understood.

11.3 Fixed radio linksFixed point-to-point radio links are a vitalcomponent of the UK's telecommunicationsinfrastructure. They carry trunk telephoneservices, television signals, mobile phoneservices, government and defencecommunications and many private and corporatetelephone links over large distances. Most ofthese are at microwave frequencies, similar tothose used by mobile phones. The wind turbineclearance zones around point-to-pointmicrowave links are relatively narrow, althoughit is not uncommon for an operator to require aclearance zone of as much as 250m on eitherside of a link whose calculated clearance maybe as little as 25m.

11.4 Scanning telemetry systemsThe water and power industries use scanningtelemetry systems to monitor and control sub-stations, water and sewage works, pipelines andsupply networks. These systems work in the UHF

band and, similar to television re-broadcastlinks, transmit over a wider zone and aretherefore more vulnerable to multi-path effectsfrom reflecting objects such as wind turbines.Consequently, the requested clearance zonesmay be large. Ofcom recommends thatconsultation be undertaken for any wind projectwithin 1km of a scanning telemetry station.

11.5 A solvable problemThe seriousness of telecommunications issueswill usually depend on the type of signal thatproposed wind farms will interfere with. In mostcases, local interference of TV reception can besolved using relatively low-cost measures forthe households affected and these should beidentified and planned for in the consentsprocess. However, potential interference of fixedradio links and other key infrastructure is moreserious and in some cases will not be easilysolved. Early identification of such issues bydevelopers should ensure that proposals onlycome forward where such problems are minorand can be mitigated.

FURTHER INFORMATION

‘The Impact of Large Buildings and Structures (including Wind Farms) on Terrestrial TelevisionReception’ – BBC/Ofcom report -www.bbc.co.uk/reception/factsheets/pdfs/buildings_factsheet.pdf

Office of Communications (Ofcom) - www.ofcom.org.uk


In 1995 Windjen Power Ltd, based in Colwyn Bay, ran a wind energy exhibition at an agriculturalshow where Mr Guto Jones, owner of Blaen Bowi Farm near Newcastle Emlyn, Carmarthenshire,expressed an interest. The company carried out an analysis of the suitability of his Moelfre Hill site,deemed it suitable and entered into a lease agreement with him for 25 years to erect three 1.3 MWturbines.

Case studyTV Signal Interference – Blaen Bowi, Wales

Windjen Power Ltd commissioned Crown CastleUK, the primary broadcast transmission companyin the UK, to carry out a survey to establishwhat effect the turbines would have on TVreception. Whilst not 100% conclusive, thesurvey identified that a repeater would berequired on a mast at Llandyfriog. The reportalso stated that the full effect on TV receptionwould not become apparent until the wind farmwas operational.

A local electrical/aerial engineer was employedto remedy interference issues once the projectwas operational in July 2002. Some 26households from surrounding villages did reportproblems with their TVs. All reports of TVinterference up to an 8-10 mile radius wereinvestigated and dealt with as they werereceived. Rectifying the interference onanalogue signals for television took betweennine to 12 months. An added bonus is that

With the erection of three turbines, all reports of TV signal interference within a radius of 8–10 miles were resolved. Somefamilies now receive additional Channel 5.

© W

indj

en P

ower

Ltd



• Windjen Power Ltd is applying thisexperience to the Tir Mostyn & Foel Gochwind farm under construction some 8kmsouth west of Denbigh, North Wales that isdue for commissioning in August 2005. It willcomprise 25 Gamesa turbines with a totalcapacity of 21.3 MW. Windjen Power Ltd hassubmitted electromagnetic interferenceassessment and consultation documents aspart of the planning application stating theremay be similar interference issues as BlaenBowi and identifying solutions.

• This case study shows how simple solutionscan often be found to problems such as TVinterference, and that good consultation withlocal residents is essential.

• Repeater transmitters are just one of anumber of options available to developers. Insome cases, the installation of satellite TV ataffected households is an alternative option.

Key facts:

• It took six years from locating the BlaenBowi site to commissioning the turbines.Significant changes were made to optimisethe design, taking into consideration visualand landscape considerations.

• By erecting the wind turbines the signal pathfrom Mast 1 to Mast 2 was intersected tosome degree, and there were two stages tosolving the problem.

• Firstly a relay antenna was placed on anexisting Mast 3 allowing the signal fromMast 1 to be sent to Mast 3 and then toMast 2, bypassing the wind turbines.

• The second stage was to alter the individualhousehold TV aeriels that would haveoriginally received a signal from Mast 1.These ariels were adjusted to receive thesignal from Mast 2. The costs were in twoparts, the additional antenna on Mast 3, andthe ariel adjustment at individual properties.

Case study: TV Signal Interference – Blaen Bowi, Wales

some unaffected families now receive Channel5. The planning authority agreements stated alimit of £5000 that the developer was requiredto spend on the problem. Windjen has spent£33,000 in resolving TV problems.

The company has recently submitted a planningapplication to extend Blaen Bowi by a furtherthree 1.3 MW turbines. On the Blaen Bowi windfarm extension planning application, theEnvironmental Statement includes consultationwith the relevant bodies and offers potentialsolutions.

”Problems of this nature can bequickly resolved given theunderstanding we have gained.Measures can also be put in place tominimise the TV receptioninterference after wind farmcommissioning.”

D. JonesManaging Director, Windjen Power Ltd.


12 The process of wind farm development

Assessment Stage

Site selection

Wind power developer looks at potential sites to assess their suitability, taking account of technical,commercial and environmental constraints. Desk-based research will be carried out to see whether sites meetessential criteria, such as:• Suitable wind resource• Access to the local electricity distribution system• Local road access• Site size and availability (to determine viability)• Site ownership• Environmental and radar/aviation considerations

There may also be initial consultation with the local planning authority and statutory consultees to identifypotential issues that need to be addressed – the local community may also be approached.

Feasibility

Once a potential site has been identified, the developer will conduct a more detailed feasibility study,including:• A more detailed technical assessment• An economic assessment• An appraisal and scoping exercise• An assessment of planning constraints (including radar/aviation)• A technical wind assessment (usually using anemometer masts)

Site visits will be required and the developer will need to agree the scope of the EIA with the relevantauthorising body. Consultation with the local community should also take place at this stage if it has notalready.

Detailed Assessment

If the proposed site looks to be commercially and environmentally viable, the developer will undertake adetailed assessment, where the exact design and layout of the turbines will be decided. The detailedassessment is likely to include:• An EIA, if one is required. This will assess, among other things: wildlife and habitat impacts, visual and

landscape impacts, and noise• Detailed community consultation, to help determine appropriate turbine layout and design• Consultation with the appropriate statutory and non-statutory consultees• Detailed economic assessment and securing finance for the project


YES NO


Planning Consent Stage

England, Scotland & Wales Northern Ireland

Proceed to Implementation Stage

Project over 50 MW?

NO YES

Local planning decisions

For projects under 50 MW,the local planning authority(LPA) will handle theplanning application for awind power development.For larger projects, this willbe accompanied by anEnvironmental Statement(ES). A decision must begiven in eight weeks, orsixteen for projectsaccompanied by an ES.

This stage includes a periodof statutory consultation,and members of thecommunity are also able tomake representations oncethe application is put beforethe planning committee,who make the final decision.

Planning appeal

Appeal will be heard by therelevant national body:

England & Wales - thePlanning Inspectorate

Scotland - Scottish ExecutiveInquiry Reporters Unit

Northern Ireland - NorthernIreland Planning AppealsCommission

The planning inspectoratecan decide to either hear thecase through written orinformal evidence, or requesta local public inquiry.

PROJECT REJECTED

Developer mustreconsider proposaland/or find a newsite

Project ‘called in’

At any point in the processabove, the Secretary of Statewith responsibility for localgovernment and planningissues (for projects inEngland, Wales and NorthernIreland), or the ScottishExecutive (for projects inScotland) can ‘call in’ theplanning application to bedecided nationally. This willautomatically require a localpublic inquiry to take place.

National consent decisions

Energy projects above 50MW in Great Britain areautomatically referred to therelevant national authorityfor a decision under Section36 of the Electricity Act1989. The Department ofTrade and Industry dealswith projects in England andWales and the ScottishExecutive with those inScotland.

Consent and planning

All wind developmentsrequire planning permissionfrom the Department ofEnvironment, and underarticle 39 of the Electricity(NI) Order 1992, all energyprojects over 10 MW mustalso obtain consent from theDepartment of Enterprise,Trade and Investment.

Decision

YES NO

Decision

All Projects

YES

Decision

NOYES NO

Decision



Implementation Stage

Construction

Once the project is approved and finance is in place, the developer will hand over responsibility for the site tothe lead contractor, who will handle the construction process. The developer will also have to arrange for anywork to allow the wind farm to connect to the local distribution or transmission network. If an EnvironmentalManagement Plan has been agreed (depending on the nature, size and location of the site), it will beimplemented at the earliest opportunity. The construction process generally takes 6-12 months, depending onthe size of the project. The local community can be kept informed of progress using an information boardsystem, or an announcement in the local newspaper.

Commissioning

Once construction is complete and grid connections have been made, the wind farm will be ready forcommissioning. This will involve ‘switching on’ the turbines for the first time, allowing wind-generatedelectricity to flow to the grid for the first time. Developers will often organise a ceremony to celebrate thecompletion of the project.

Operation & Maintenance

Developers have responsibility for the operation of their wind energy project throughout its lifetime and thepublic should be notified of any changes of operation. Maintenance activities will need to take place regularlyfor individual turbines and associated infrastructure to ensure maximum performance.

Decommissioning / Repowering

At the end of their working lives (usually 20 years), the wind turbines will usually be removed and thematerials recycled. The site may then be ‘repowered’, where new turbines are installed in their place, or fullydecommissioned. Repowering offers the potential for significant increases in output from existing sites, as thelatest technology will be installed. However, in some cases the original planning consent may stipulate thatthe site is decommissioned. The developer may then choose to apply for planning permission to repower thesite, or be forced to decommission it. This would require removal of the foundations and restoration of the siteas close as possible to its previous condition.


Alternating current (AC) - Flow of electricitythat constantly changes direction betweenpositive and negative sides. Electricity producedin the UK moves in current that shifts directionat a rate of 50 times per second (50 Hertz,50Hz).

Base load - The minimum load experienced byan electric utility system over a given period oftime.

Baseload capacity - Generating equipmentoperated to serve loads 24-hours per day (eg.nuclear power plants).

BETTA – the British Electricity Transmission andTrading Arrangements introduced in April 2005,extending NETA to Scotland.

Capacity - The maximum load a generatingunit, generating station, or other electricalapparatus is rated to carry.

Capacity factor - The ratio of the electricalenergy produced by a generating unit relative tothe electrical energy that could have beenproduced at continuous full power operationduring the same period of time. The CapacityFactor for wind energy in the UK is typicallybetween 20% and 40%.

Capacity value – Sometimes referred to ascapacity credit, this is an expression of thepercentage of conventional generation that canbe displaced by wind generation. The capacityvalue may be equal to the capacity factor at lowlevels of wind penetration, but will be lower aspenetration increases.

CCGT - Combined cycle gas turbine; modern gaspowered electricity generating technology.

Conservation - A foregoing or reduction ofelectric usage for the purpose of saving naturalenergy resources and limiting peak demand inorder to ultimately reduce the capacityrequirements for plant and equipment.

Current (electric) - Flow of electrons in anelectric conductor.

Demand (electric) - The rate at which electricalenergy is delivered to or by a system. Demandis expressed in kW, kVA, or other suitable unitsat a given instant or over any designated periodof time.

Defra - Department of Environment, Food andRural Affairs

Distributed generation (embeddedgeneration) - A distributed generation systeminvolves small amounts of generation located ona utility's distribution system for the purpose ofmeeting local (substation level) peak loadsand/or displacing the need to build additional(or upgrade) local distribution lines.

DTI - Department of Trade and Industry

Distribution - The system of wires, switches,and transformers that serve neighbourhoods andbusinesses; classified as 132,000 volts andbelow in England and Wales (132kV isconsidered to be part of the TransmissionNetwork in Scotland). A distribution systemreduces the voltage from high-voltagetransmission lines (275,000 volts or 400,000volts) to a level that can be distributed tohomes or businesses; 132,000V, 33,000V,11,000V, 3,300V, 440V.

Distribution system - That part of the electricsystem that delivers electrical energy toconsumers.

DSO, DNO - Distribution System (or Network)Operator.

Embedded generation – see distributedgeneration

Energy - This is broadly defined as the capabilityof doing work. In the electricity industry, energyis more narrowly defined as electricity suppliedover time, normally expressed in kilowatt-hours.

Energy consumption - The amount of energyconsumed in the form in which it is acquired bythe user. The term excludes electrical generationand distribution losses.

Glossary of terms


Energy efficiency - Programmes that reduceenergy consumption whilst maintaining a givenlevel of output.

Energy mix - the distribution or proportion ofdifferent energy sources within the total energysupply.

Energy resources - Everything that could beused by society as a source of energy.

Energy source - A source that provides thepower to be converted to electricity e.g. hydro,solar, wind, biomass, fossil fuel, nuclear fuel.

Energy use - Energy consumed during aspecified time period for a specific purpose(usually expressed in kWh).

Generation (Electricity) - Process of producingelectric energy by transforming other forms ofenergy.

Generator - Machine used to convertmechanical energy into electrical energy.

Gigawatt (GW) - The unit of electrical powerequal to one thousand-million watts, or onethousand megawatts.

Grid - Matrix of an electrical distribution system,the National Grid in the UK.

Installed capacity - The total generating units'capacities in a power plant or on a total utilitysystem. The capacity can be based on thenameplate rating or the declared net(dependable) capacity (DNC).

Intermittent resources - Resources whoseoutput depends on some other factor thatcannot be controlled by the utility e.g. wind orsun. Thus, the capacity varies by day and byhour.

Kilowatt (kW) - The electrical unit of powerequal to 1,000 watts.

Kilowatt-hour (kWh) - The basic unit of electricenergy equal to one kilowatt of power suppliedto or taken from an electric circuit for one hour.

Load - The amount of electric power deliveredor required at any specified point or points on asystem. Load originates primarily at the powerconsuming equipment of the customer.

Load factor - The ratio of the average loadsupplied to the peak or maximum load during adesignated period. Similar to capacity factor, butmore often used when describing conventionalplant.

Losses - The general term applied to energy(kWh) and capacity (kW) lost in the operation ofan electric system. Losses occur principally asenergy transformations from kWh to waste-heatin electrical conductors and apparatus.

Megawatt (MW) -One million watts. A largecoal-fired power station in the UK typically hasan installed capacity of between 2,000 MW and4,000 MW

Megawatt-hour (MWh) - One thousandkilowatt-hours or one million-watt hours.

NETA - the New Electricity Trading Arrangementsintroduced in March 2001 for England andWales, and governed by the Balancing andSettlement Code (see BSC). Now superseded byBETTA.

Off-peak - Periods of relatively low systemdemands.

OFGEM - the Office of Gas and ElectricityMarkets; the energy regulator for the GB gasand electricity sectors.

Outage - Time during which service isunavailable from a generating unit, transmissionline, or other facility.

Payback - The length of time it takes for thesavings received to cover the cost ofimplementing the technology.

Peak - Periods of relatively high systemdemands.

Peak demand - Maximum power used in agiven period of time.

Glossary of terms


Phase - One of the characteristics of the electricservice supplied or the equipment used.Practically all residential customers have single-phase service at 240 volts. Large commercialand industrial customers typically have three-phase service from 440 volts upwards.

Plant - A facility containing prime movers,electric generators, and other equipment forproducing electric energy.

Power - The rate at which energy is transferred.

Power plant - A generating station whereelectricity is produced.

Production - The act or process of generatingelectric energy.

Pumped storage - A facility designed togenerate electric power during peak loadperiods with a hydroelectric plant using waterpumped into a storage reservoir during off-peakperiods.

Regulation - An activity of government tocontrol or direct economic entities byrulemaking and adjudication.

Reliability - Electric system reliability has twocomponents - adequacy and security. Adequacyis the ability of the electric system to supply theaggregate electric demand and energyrequirements of the customers at all times,taking into account scheduled and unscheduledoutages of system facilities. Security is theability of the electric system to withstandsudden disturbances such as electric shortcircuits or unanticipated loss of system facilities.

Renewable energy - the term used to coverthose energy flows that occur naturally andrepeatedly in the environment, it includes allenergy derived from the sun (solar, wind, ocean,and hydro power, plus biomass), andgeothermal sources.

Energy that is capable of being renewed by thenatural ecological cycle, generally wind, wave,tidal, solar, hydro, biomass.

Renewables Obligation - support mechanismaimed at increasing the percentage ofrenewable energy generation on the nationalgrid. The Renewables Obligation works byplacing an obligation on electricity suppliers tosource an increasing percentage of supply fromrenewables. Separate obligations apply inScotland and Northern Ireland.

Reserve capacity - Capacity in excess of thatrequired to carry peak load.

ROCs - Renewable Obligation Certificates; thetradable ‘currency’ of the RO.

Running and quick-start capability - Generallyrefers to generating units that can be availablefor load within a 30-minute period.

Scheduled outage - An outage that resultswhen a component is deliberately taken out ofservice at a selected time, usually for thepurposes of construction, maintenance, ortesting.

Spinning reserve - Reserve generating capacityrunning at zero load.

Substation - A facility used for switching and/orchanging or regulating the voltage of electricity.Service equipment, line transformerinstallations, or minor distribution ortransmission equipment are not classified assubstations.

Supplier - A person or corporation, generator,broker, marketer, aggregator or any other entity,that sells electricity to customers, using thetransmission or distribution facilities of anelectric distribution company.

System (Electric) - Physically connectedgeneration, transmission, and distributionfacilities operating as a single unit.

Terawatt (TW) - One thousand gigawatts

Therm -

Transformer - A device for changing the voltageof alternating current.

Glossary of terms


Transmission - The act or process oftransporting electric energy in bulk.

Transmission and distribution (T&D) losses -Losses that result from the heating effect ofcurrent as it flows through wires to travel fromthe generation facility to the customer. Becauseof losses, the electricity produced by the utilityis greater than the electricity that shows up onthe customer bills.

Transmission and distribution (T&D) system -An interconnected group of electric transmissionlines and associated equipment for themovement or transfer or electrical energy inbulk between points of supply and points atwhich it is transformed for delivery to theultimate customers.

Transmission lines - Heavy wires that carrylarge amounts of electricity over long distancesfrom a generating station to places whereelectricity is needed. Transmission lines are heldhigh above the ground on tall towers calledtransmission towers.

Transmission network - the electricitytransmission system operating at voltages above132kV (in England and Wales) and including132kV in Scotland)

TSO, TNO – (Electricity) Transmission System (orNetwork) Operator

Upgrade - Replacement or addition of electricalequipment resulting in increased generation ortransmission capability.

Utility - A regulated vertically-integratedelectricity company. "Transmission utility" refers tothe regulated owner/operator of the transmissionsystem only. "Distribution utility" refers to theregulated owner/operator of the distributionsystem which serves retail customers.

Volt – the unit of electrical potential. It is theelectromotive force which, if steadily applied toa circuit having a resistance of one ohm, willproduce a current of one ampere.

Volt-amperes - The volt-amperes of an electriccircuit; the mathematical product of the voltsand amperes. Equals the power in a directcurrent circuit.

Voltage - Measure of the force of movingelectrical energy.

Watt - The electrical unit of power or rate ofdoing work. One horsepower is equivalent toapproximately 746 watts.

Watt-hour - One watt of power expended forone hour.

Glossary of terms


References

1 Defra (2005). One future - different paths. Available at:www.sustainable-development.gov.uk/documents/publications/SD%20Framework.pdf

2 Intergovernmental Panel on Climate Change (IPCC) (2001). Climate Change 2001: Synthesis Report. Available at:http://www.grida.no/climate/ipcc_tar/vol4/english/004.htm

3 IPCC (2001). Climate Change 2001: The Scientific Basis. Available at:http://www.grida.no/climate/ipcc_tar/vol4/english/076.htm

4 King, D. (2004). Climate Change Science: Adapt, Mitigate or Ignore? Science, Jan. 9, 2004.

5 Kyoto Protocol to the United Nations Framework Convention on Climate Change (1997). Available at:http://unfccc.int/essential_background/kyoto_protocol/items/1678.php

6 Carbon Dioxide Information Analysis Center (CDIAC) (2004). Oak Ridge National Laboratory. Available at:http://cdiac.esd.ornl.gov/home.html

7 DTI (2005). Energy Trends March 2005. Available at: http://www.dti.gov.uk/energy/inform/energy_trends/mar_05.pdf

8 Defra (2005). E-Digest Environmental Statistics. Available at:http://www.defra.gov.uk/environment/statistics/globatmos/gagccukem.htm

9 Riso National Laboratory, Denmark. Website available at: http://www.risoe.dk/

10 DTI (2000). The UK Wind Resource. Available at:http://www.dti.gov.uk/energy/renewables/publications/pdfs/windfs8.pdf

11 Garrad Hassan and Partners Limited (Garrad Hassan) (2001). Scotland’s Renewable Resource 2001 – Executive Summary.Report completed for Scottish Executive, Glasgow, available at:http://www.scottish.parliament.uk/enterprise/inquiries/rei/ec04-reis-scotenvlinkfollowup2.pdf

12 DTI (2001). Offshore Wind Energy. Available at:http://www.dti.gov.uk/energy/renewables/publications/pdfs/windfs1.pdf

13 DTI (2002). Future Offshore consultation document. Available at:http://www.dti.gov.uk/energy/leg_and_reg/consents/future_offshore/FutureOffshore.pdf

14 Figures from BWEA website at: http://www.bwea.com/map/index.html

15 DTI (2004a). Digest of UK Energy Statistics 2004. Published by The Stationery Office. Available at:http://www.dti.gov.uk/energy/inform/dukes/index.shtml

16 DTI (2005). 2005-6 Review of the Renewables Obligation – preliminary consultation document. Available at:http://www.dti.gov.uk/renewables/policy_pdfs/renewobligarevreport.pdf

17 Dale et al. (2003). Total cost estimates for large-scale wind scenarios in UK. Energy Policy 32, pp. 1949-1956.

18 Danish Wind Turbine Manufacturers Association (1997). The Energy Balance of Modern Wind Turbines. Available from:http://www.windpower.org/en/tour/env/enpaybk.htm; citations in Wind Power Weekly (1992). Available at:http://www.awea.org/faq/bal.html; and Milborrow, D. (1998). Dispelling the Myths of Energy Payback Time. Wind StatsNewsletter, Vol. 11, No.2.

19 Vestas (2004). Energy balance information. Available at:http://www.vestas.com/uk/environment/2005/energy_balance/energy_balance.asp

20 Enviros (2005). Generic wind turbine power curve.

21 NGC (2003). Seven Year Statement. Available at:http://www.nationalgrid.com/uk/library/documents/sys_03/default.asp?sNode=SYS&action=&Exp=Y

22 House of Lords Science & Technology Select Committee (2004). Fourth Report: Renewable Energy – Practicalities. Availableat: http://www.publications.parliament.uk/pa/ld200304/ldselect/ldsctech/126/12602.htm

23 E.on Netz (2004). Wind Report 2004. Available at: http://www.eon-netz.com


References

24 Garrad Hassan (2005). Data kindly provided from the GH Forecaster. http://www.garradhassan.com

25 Carbon Trust / DTI (2004). Renewables Network Impacts Study. Available from:http://www.carbontrust.org.uk/carbontrust/about/publications/Renewables%20Network%20Impact%20Study%20Final.pdf

26 Nuclear Energy Agency/IEA (2005). UK contribution to: Projected costs of generating electricity, 2005 update.

27 Non-Fossil Purchasing Agency (2005). Average NFFO Prices. Available at: http://www.nfpa.co.uk/index.cfm?pid=33

28 Oxford Economic Research Associates (2004). Results of renewables market modelling. Available at:http://www.dti.gov.uk/renewables/policy/oxeraresults.pdf

29 Milborrow, D. (2005). Goodbye gas and squaring up to coal. Windpower Monthly, January 2005.

30 IEA/OECD (2005). Projected costs of generating electricity - 2005 update. International Energy Agency, Paris.

31 Platts (2005). “Platts price data”. Power UK, February 2005.

32 ETSU (1996). R-99: A review of the UK onshore wind energy resource.

33 ETSU (1999). R-122: New and renewable energy: prospects in the UK for the 21st century.

34 DTI (2003). Modelling carried out for economics paper No 4. - Options for a low carbon future.

35 Dale, L., Milborrow, D., Slark, R. and Strbac, G. (2003). A shift to wind is not unfeasible. Power UK, March 2003.

36 Black and Veatch Corp (2004). Economic impact of renewable energy in Pennsylvania. Available at:http://www.bv.com/energy/eec/studies/PA_RPS_Final_Report.pdf

37 Harrison, L, 2004. Wind economics set to beat gas in Ireland. Windpower Monthly, December 2004.

38 German Energy Agency, 2005. Planning of the grid integration of wind energy in Germany offshore and onshore up tothe year 2020.

39 Oxera, 2004. Security of supply, energy investment requirements and cost implications. Report for Centrica

40 Milborrow, D. (2005). Personal correspondence. (This analysis was carried out under a separate contract to the CarbonTrust and their permission to quote the results is gratefully acknowledged.)

41 Awerbuch, S, 2003. Determining the real cost -- why renewable power is more cost-competitive than previously believed.Renewable Energy World, March/April 2003.

42 HMT/Defra (2002): Estimating the Social Cost of Carbon Emissions. Available at:http://www.hm-treasury.gov.uk/media/209/60/scc.pdf

43 NAO (2005). Department of Trade and Industry: Renewable Energy. Available at:http://www.nao.org.uk/publications/nao_reports/04-05/0405210.pdf

44 DEFRA (2004). Energy Efficiency: The Government’s Plan For Action. Available at: http://www.official-documents.co.uk/document/cm61/6168/6168.pdf

45 DTI spokesperson, as quoted in the Guardian, 11th February 2005. Available at:http://money.guardian.co.uk/utilities/story/0,11992,1410930,00.html

46 DTI/DEFRA (2003). Energy White Paper: Our energy future - creating a low carbon economy. Available at:http://www.dti.gov.uk/energy/whitepaper/ourenergyfuture.pdf

47 Cabinet Office (2002). The Energy Review. Available at: http://www.number-10.gov.uk/su/energy/TheEnergyReview.PDF

48 Data obtained from RESTATS service provided by Future Energy Solutions for the DTI. Public data available at:www.restats.org.uk

49 Jain, R.K. et al. (2002). Environmental Assessment. McGraw-Hill, New York.

50 Friends of the Earth (2001). How to Win – saving wildlife sites. Available at:http://www.foe.co.uk/resource/local/saving_wildlife_sites/getting_started/saving_wildlife_sites_3.pdf


References

51 RSPB (2004). Wind farms and birds, RSPB information sheet. Available at:http://www.rspb.org.uk/Images/Pages%20from%20Wind%20farms%20and%20birds_tcm5-51248.pdf

52 Scottish Executive (2002). PAN 45: Renewable Energy Technologies. Edinburgh.

53 Jakobsen, J. (2004). Infrasound Emission from Wind Turbines. Proceedings from Low Frequency 2004: 11th Internationalmeeting on low frequency noise and vibration and its control. Danish Environmental Protection Agency.

54 Leventhall (2003). A review of published research on low frequency noise and its effects. A report for DEFRA.

55 WHO (1999). Guidelines for Community Noise. Available at: http://www.who.int/docstore/peh/noise/guidelines2.html

56 BSI (1997). BS4142: Method for rating industrial noise affecting mixed residential and industrial areas.

57 ETSU (1996). ETSU R97: The Assessment & Rating of Noise from Wind Farms. Available at:http://www.dti.gov.uk/energy/renewables/publications/noiseassessment.shtml

58 DTI (2003). Attitudes and Knowledge of Renewable Energy amongst the General Public - Report of Findings.

59 EC (2002). Energy: Issues, Options and Technologies Science and Society. The European Opinion Research Group (EORG) forthe Directorate-General for Research, EUR 20624.

60 EWEA (2003). Wind Directions (bimonthly magazine). September/October 2003.

61 Scottish Executive (2003). Public Attitudes to Windfarms: A survey of Local Residents in Scotland. Research Studyconducted by MORI (Scotland) Social Research Institute. Scottish Executive Social Research. Available at:http://www.scotland.gov.uk/library5/environment/pawslr.pdf

62 The Royal Institution of Chartered Surveyors (RICS) (2004). Wind farms hit house prices. Available at:http://www.rics.org.uk/Property/Residentialproperty/Residentialpropertymarket/wind+farms+hit+house+prices.htm

63 DTI (2004). Renewables Supply Chain Gap Analysis. Available at:http://www.dti.gov.uk/renewables/publications/pdfs/renewgapreport.pdf

64 South West Renewable Energy Agency (2004). South West Public Engagement Protocol and Guidance for Wind Energy.Available at: http://www.regensw.co.uk/advice/la-windprotocol.asp

65 STASYS Ltd, Wind Turbines and Aviation Interests - European Experience and Practice, ETSU W/14/00624/REP, DTI PUBURN No. 03/515, 2002, p.iii

66 Enterprise and Culture Committee, Scottish Parliament (2004). Evidence Received for Renewable Energy in ScotlandInquiry: submission from National Grid Transco. Available at:http://www.scottish.parliament.uk/business/committees/enterprise/inquiries/rei/ec04-reis-ngt.htm


Wind Power in the UK: Annexes

These technical annexes set out background information in much greater detail than the maindocument. They are meant as a source of technical data and references for readers interested inknowing more about the subject. The data sources are not exhaustive but should provideinformation that will satisfy most readers’ needs.


Rotor bladesWind turbine rotor blades are eithermanufactured from glass fibre reinforcedpolyester resins (small blades) or more typicallyfrom pre-impregnated glass reinforced epoxyresin (larger blades) or wood laminates, andcomprise aerodynamic shells bonded to a spar.Carbon fibre reinforcement is a common featureon larger blades, adding strength while reducingweight. Studs are embedded in the blade rootfor attachment to the rotor hub. The commonlyused number of rotor blades per turbine isthree.

RotorThe bladed rotor extracts kinetic energy fromthe wind flowing through it. The poweravailable varies with the cube of the windspeed, i.e. double the wind speed produceseight times the power. The slow speed (13-30rpm) rotor is connected to a gearbox which

increases the rotational speed to drive anelectrical generator (1500rpm). The turbulentand gusty nature of wind flow requires theamount of energy extracted by the rotor to belimited in order to protect the gearbox,generator and the wind turbine structure itselffrom damaging loads. Control is achieved eitherby aerodynamic stall or by changing the angle(pitch) of the rotor blades. Stall regulatedmachines effectively run at constant speed,pitch regulated machines can run at variablespeed, thereby reducing loads on the drive train.

GearboxAt the heart of a wind turbine drive train is thegearbox which is designed to increase the lowspeed, high torque of the rotor to the highspeed, low torque of the electrical generator.Gearboxes can be multi-stage helical, planetary,or hybrid designs. Some designs of wind turbinemount the rotor directly to the gearbox, othersutilise a separate slow-speed shaft and bearing

Annex AWind power technology

Figure 1: Nacelle components in a modern geared wind turbine

1 Hub Controller2 Pitch Cylinder3 Main shaft4 Oil Cooler5 Gearbox6 Power Controller7 Parking Brake8 Service Crane9 Transformer10 Rotor Hub11 Blade Bearing12 Rotor Blade13 Rotor Lock14 Hydraulic Unit15 Machine Foundation16 Yaw Gears17 Generator18 Generator Cooler19 Anemometer

Illustration courtesy of Vestas Wind Systems A/S


arrangement to support the rotor. Other designsdispense with the gearbox altogether and aredirectly coupled to a large diameter wound-rotorgenerator running at rotor speed. Direct-drivemachines are much quieter than machines witha gearbox as they produce less mechanical ortonal noise.

GeneratorWind turbines with gearboxes can utiliseindustry standard high speed induction orsynchronous generators, the wide choice andavailability keeping costs low. Direct-drivemachines require bespoke wound-rotorgenerators. Variable speed operation, with theadvantages of low drive train loads, requires theapplication of power electronics to deal withfrequency variations before connection to thefixed frequency grid. The wind industry hadbenefited from advances in power electronics interms of power quality, load reduction, andenhanced energy output.

Control systemsThe success of modern wind turbine generatorsowes much to the integration and control ofcomplex dynamic systems. Aerodynamicallyefficient rotors depend upon pitch control tomaintain optimum energy capture through awide range of wind speeds. There is a yawsystem to rotate the nacelle so the rotor alwaysfaces the prevailing wind. There is control of thevariable speed rotor which is allowed to respondto gusts and load changes to reduce drive trainloads. There is control of the output power fromthe generator in terms of frequency and powerquality so that the wind farm’s variable outputhas a benign effect on the electricity grid whensynchronised. Wind farms operate fullyautomatically, entirely unmanned and aremonitored remotely, constantly logging data formachinery condition monitoring, technicalperformance, power generated etc. This is atestament to the high levels of availability

(98%) and reliability, with only 40 hoursmaintenance required per year. A wind turbineis designed to operate for over 120,000 hoursover a 20-year design life.

TransformersMost wind turbines generate at industrystandard 3 phase voltages, typically 460 or 690volts. Connection to the electricity grid for exportof the power is generally made at 33,000 volts(33kV) or even 132kV depending on the totalpower output of the wind farm. Depending onthe wind farm electrical design, voltagetransformers may be installed in the nacelle, thetower base, a separate enclosure adjacent to thetower, or the wind farm export substation.

Power quality and powerelectronicsThe advent of variable speed rotors andadvances in industrial full-power electronicshave been exploited by the wind energyindustry to produce machines with high qualityelectrical output that have a low impact on thegrid. The wind energy resources identified onland and offshore and the 15% target forelectricity from renewable sources by 2015 canreadily be met by wind energy alone with nodetrimental impact on the transmission anddistribution grid.

TowerMost wind turbines use tubular steel towerstypically tapering from 4.0m diameter at groundlevel to 2.5m diameter for connection to thenacelle. A modern 2MW machine with a rotordiameter of 80m may utilise a range of towerheights from 60m to 90m depending on annualmean wind speed and site topography. Thereare an increasing number of developments ofone or two wind turbines in semi-urban orindustrial landscapes where the annual meanwind speed would not initially attract a

Annex A: Wind power technology


commercial developer but where, with theevolution of high energy capture rotors coupledwith increased tower heights, a commercialproposition can be developed. Prefabricatedconcrete towers with heights in the 100-110mrange look set to continue this trend.

Annex A: Wind power technology

FURTHER INFORMATION

“Wind Energy – The Facts” – European Wind Energy Association -http://www.ewea.org/06projects_events/proj_WEfacts.htm


Background to generation costsWorld wind energy capacity has doubled everythree years since 1990. Each doubling wasaccompanied by a 15% reduction in the price ofwind turbines. The price of wind-generatedelectricity fell more rapidly, as there were alsoimprovements in energy productivity, partlybecause machines became more reliable, partlydue to a trend towards larger machines.Although the growth in capacity slowed in 2004– when the annual increase was about 20% –manufacturers continue to innovate and so thedownward price trends seem set to continue.

To gain an appreciation of wind turbine andwind-generated electricity prices, it is necessaryto examine the prices of wind turbines and ofwind farms and their energy productivity. Thesedepend on factors such as location, the size ofthe machines, and the size of the wind farm.Energy production depends on the site windspeed and has a crucial effect on power prices.

Starting with the wind turbines, Figure 2 trackslist prices from a leading manufacturer from1990 to 2004.1 Although list prices are only aguide, and many orders are placed at lowerprices, the overall trend – falling from just over€1400/kW in 1990 to €830/kW in 2004 – isstrongly downward.

In 1990, the largest size of machine offered bythe manufacturer was 150 kW, and it hasincreased steadily since that time. The sharpdrop in prices between 1993 and 1994 reflectedan increase in size from 450 kW to 600 kW andthe 2004 price (€830/kW, or £570/kW) relatesto a 2000 kW machine.

[Note: As much of the source data for Figs 1-3,and Table 1 are in euro, they have not beenconverted, but generation costs – quoted later –are in UK currency]

Annex BNetwork integration and costs

Figure 2: Wind turbine list prices (€/KW)

0

200

400

600

800

1000

1200

1400

1600

1990 1992 1994 1996 1998 2000 2002 2004

Year

List

pri

ce (

/kW

)

List price


From 1990 to 2002, world wind energy capacitydoubled every three years. Few other energytechnologies are growing, or have grown, atsuch a remarkable rate. In 2003, the growth ratewas around 25%, with an extra 8200 MWinstalled, and a similar quantity was installed in2004. Total capacity is now nearly 48,000 MW,with around 888 MW installed in the UK.

Whilst cost reductions with increased volume ofproduction are well known in many technologiesthe ‘learning curve’ (as it is termed) for wind iswell in excess of early expectations. Based onan analysis of the relative amounts of labourand material cost in wind turbines Bergeypredicted an 8% reduction of cost per unitdoubling of capacity in 1991; what is actuallybeing achieved is nearly double that figure.2 Thedata quoted above is consistent with a 15%learning curve ratio, and other authors havederived similar figures.

The effect of turbine sizeThe steady decrease in costs has been due, inpart, to the move towards larger machines. In1992 the cheapest machine (per kW) was ratedat 300 kW and it is now around 1500 kW. Largermachines tend to be slightly more expensive.When used in wind farms, however, fewermachines realise savings on foundation costs,transport, electrical connections and operationalcosts, making larger machines potentially moreattractive.

The economics for small-scale wind turbines (1-200 kW) are quite different, with the smallestsized machines (1-30 kW) coming out the mostexpensive per unit of installed capacity. Thisreport does not look at small-scale wind power,but it is important to recognise these differences.

Breakdown of wind farm costs The total installed cost of a wind farm includes‘balance of plant’ costs, such as the cost of

foundations, transport and internal electricalconnections. These add between 15 and 30% tothe cost of the wind turbines, and there arewide variations which depend on the difficultiesof construction and the size of the project. Inaddition, the cost of the grid connection canoften add a substantial sum to the project cost.

A typical cost breakdown for an onshore windfarm is3:Turbines 72%Foundations 6%Electrical connections 2%Planning 4%Grid connection 10%Miscellaneous 6%

Table 1 summarises a number of recent windfarm published prices, drawn from a database ofabout 30 onshore projects cited in the journal‘Windpower Monthly’ in 2004.

There are wide variations, but the averageonshore price is €980/kW (range €707-1350/kW). The average offshore price is around€1600/kW (range €1250-1800/kW). The lowestprices, in each case, come from developingworld locations, especially China and India.

Operational costsOperational costs fall with increase of turbinesize. Analysis of data from German windinstallations shows that total costs fall fromaround €25/kW/yr at the 250 kW size to around€13/kW/yr at 1500 kW (Figure 3).4 These costsinclude operation and maintenance contracts,insurance and administration. In Britain,operation and maintenance costs also includelocal authority rates and the rents payable bythe plant operators to the landowners – typicallyaround 1.5% of turnover.

Annex B: Network integration and costs



Location Turbines xrating (MW)

Capacity,(MW)

Cost,(Million)

Cost,€/kW

Referencei

Canada

Spain

Australia

Ireland

Jamaica

China

Scotland

DK, Middlegrunden

DK, Horns Rev

DK, Nysted

UK, North Hoyle

20 x 1.5

Not quoted

35 x 2.00

Mixed

23 x 0.9

Not quoted

56 x 2.3

20 x 2.0

80 x 2.0

72 x 2.3

30 x 2.0

30

128

70

72

20.7

100

129

40

160

166

60

C$48

€132

AS$130

€80

$24

$94.2

£90

€50

€268

€230

£74

1008

1031

1077

1111

870

707

997

1250

1675

1389

1790

September, P.20

July, P.10

Semptember, P.16

July, P.8

July, P.27

July, P.28

Power UK January 2005

Table 1: Prices of wind farms recently completed or planned

Offshore

Figure 3: Operational cost data

1-70 71-140

141-210

211-280

281-350

351-420

421-490

491-560

561-630

771-840

981-1050

1471-1540

Size range (MW)

Cost

(€/

kW)

0

5

10

15

20

25

30

35

i Windpower Monthly (2004) except where noted


Energy productivity Larger turbines means taller turbines – whichmeans they intercept stronger winds. Thisfurther enhances their attractions as moreenergy is being squeezed out of each squaremetre of rotor area. Winds at 60m are around4% higher than winds at 45m. This correspondsto around 7% more energy.

To illustrate this point, Figure 4 shows howenergy yields vary with size of turbine. The windspeed at 10m is 5.5 m/s in every case, so thelarger the turbine, the higher the wind speedseen at hub height. This accounts for theincreasing energy productivity.

The calculation uses performance characteristicsof actual machines, based on the version with ahub height equal to rotor diameter (or thenearest hub height available).

With higher winds, the use of higher generatorratings can be economically justified, since it

will be operating at rated output for longerperiods. This also increases energy productivity.As diameters have increased - from 45 to 60metres, for example - increased ratings haveobtained around 10% more energy out of theairstream.

Differences with offshore windOne advantage of offshore wind, in manylocations – but not necessarily the UK – is thatwind speeds are higher, leading to greaterenergy productivity. In the UK and Greece,however, there are good hilltop sites wherehigher wind speeds are found. Wind speeds onScottish hilltop sites range up to 9 m/s, andabove, whereas most of the offshore sites nowbeing developed have wind speeds around 8.2to 8.6 m/s. Offshore wind energy is still at arelatively early stage of development. There arewide variations in contract costs due to thenature of the seabed, the wind regime and thegrid connection cost. Wind turbines are moreexpensive, as they need additional protection


Figure 4: Increases of yield with wind turbine size

900

950

1000

1050

1100

1150

1200

1250

1300

1350

1400

50

Rotor diameter (m)

Ann

ual y

ield

(kW

h/m

2)

45 55 60 65 70 75 80 85


against the salt spray. This takes various forms,including pressurised nacelles to ensure thatelectronic equipment is protected. The additionalcost of the wind turbines is in the range 10-15%, but the foundations, installation costs andgrid connection costs are usually significantlymore expensive. The additional costs can almostdouble the turbine costs, bringing the totalinstalled cost to €1400-1800/kW.

Wind generation costsElectricity prices for wind energy depend onboth technical and institutional factors. Theinfluence of wind speed is easy to take intoaccount, as the capacity factors of most mediumand large size wind turbines follow similartrends.

Institutional factors are diverse and lead to widevariations in price. In Denmark, for example,‘public sector’ interest rates and repaymentperiods tend to be used, whereas in the UnitedStates and the UK, where all projects areundertaken by the private sector, interest ratesare higher and repayment periods shorter.

In the UK the discount rate set by the Treasuryfor public-sector projects was 6% until 2004. Itwas replaced by a ‘social discount rate’ of 3.5%,but the guidelines still demand that account istaken of risk and so a 6% rate may be moreappropriate. Rates in the private sector arehigher. Figure 6 therefore shows prices for an8% discount rate and 15-year capital recoveryperiodi. The 8% discount rate was used by OFFERto test the commercial viability of projectsbidding into the Non-Fossil Fuel Obligation, andis probably the minimum likely to be used. Itmay not be unrealistic. If loan finance can beobtained at 5.5% (real) for 60% of project costs,

a return of 12% real on the equity could beachieved.

Figure 10 (p. 29) shows generation costestimates for a range of wind speeds andinstalled costs. The choice of installed costs isbased on an analysis of data from over 3300MW of plant installed or announced in 20045.Sample data are included in Table 1.

The costs used are:

• A low onshore cost of £560/kW- roughly onestandard deviation below the mean

• A high onshore cost of £800/kW - roughly onestandard deviation above the mean

• A low offshore cost of £1000/kW –corresponding to the early UK farm at Blythand some Danish wind farms in shallowwaters

• A high offshore cost of £1250/kW –corresponding to some of the highest prices inTable 1

As the windy sites – both onshore and offshore –tend to be more expensive to develop, therange of wind speeds corresponding to each costfigure have been restricted accordingly. Thegraph shows electricity prices, for an onshoreproject farm at £560/kW declining from around5p/kWh at 6 m/s to about 2.9p/kWh at 8 m/s.At 8 m/s and £800/kW, the generation costwould be 4p/kWh, and at a very good site (9.75m/s) the corresponding cost would be 3p/kWh.

Prices for offshore wind at £1000/kW rangefrom 6.9p/kWh at 7 m/s down to 4.9p/kWh at8.5 m/s. At £1250/kW, prices range from 6.7m/s at 8 m/s down to 5.2p/kWh at 9.25 m/s.


ii In its document “Future Offshore” the DTI used a 10% discount rate and 20-year life, which gives almost exactly the sameannual charge rate.


The effect of market supportmechanismsAs wind energy is not yet quite competitive withthe conventional sources of electricity generation,various ‘market support’ mechanisms operate.These compensate the renewable energy sourcesfor having low external costs, as governmentstend to shy away from imposing carbon taxes.(Many economists argue that carbon taxes, or capand trade schemes such as ‘domestic tradablequotas’, are the desirable long-term solution).The support mechanisms can distort the price ofwind energy: prices in Britain under the NonFossil Fuel Obligation went as low as 2p/kWh butonce the Renewables Obligation came into force,prices moved towards 7p/kWh, or above. Thissimply reflects scarcity in the early days of theObligation. Similarly, it is argued that ‘fixed-price’mechanisms tend to inhibit price reductions. Afull discussion of the types of mechanisms andprices paid is included in a recent analysis6.

Capacity valueFew renewable energy topics generate moreconfusion and controversy than that of capacityvalues (or capacity credits). The British WindEnergy Association has defined the term7:

“The reduction, due to theintroduction of wind energyconversion systems, in the capacity ofconventional plant needed to providereliable supplies of electricity.”

The importance of capacity value is thateconomic assessments include a ‘capacitydisplacement’ term on the ‘value’ side of theequation. Once the capacity value has beendetermined, the value of the displaced capacitycan be determined from a knowledge of theinstalled costs of the displaced plant and therelevant financing parameters.

Several studies of the impacts of wind haveaddressed the issue in more detail and theirconclusions are succinctly summarised in a studycarried out for the European Commission by theCEGB8:

“At low [energy] penetration the firmpower that can be assigned to windenergy will vary in direct proportionwith the expected output at time ofsystem risk.”

In practice, this statement is true for any energysource whether it is renewable or not. ‘Firmpower’ is not the same as ‘capacity value’, butthe two are linked. The reference plant today isusually combined-cycle gas turbine plant (CCGT),with a high availability – around 90% – so 360MW of firm power corresponds to about 400 MWof CCGT plant.

Several studies have examined this issue and allhave concluded that capacity credits at low windenergy penetrations in the UK are roughly equalto the ‘winter quarter’ capacity factors9. Theseclearly depend on the wind speed at particularsites, but are mostly in the range 36-42%. So1000 MW of wind plant will displace around 400MW of thermal plant.

As the amount of wind on a system increasesthe capacity credit (in fractional terms) declinesand Figure 5 shows good agreement from threestudies on the way it declines10. With 20% wind,for example, the capacity credit is about half thecapacity factor, so if the latter was 36%, say, thecapacity credit would be around 18% of therated power of the wind plant. In practice, NGThas estimated that 8,000 MW of wind mightdisplace about 3,000 MW of conventional plantand 25,000 MW of wind (20% penetration),would displace about 5,000 MW of such plant11.




Winter anticyclonesThese, it is alleged, frequently becalm thewhole country and cause problems for thesystem operator, due to the absence of anywind power, especially at periods of peakdemand. The capacity credit, it is argued, istherefore zero. However, the EnvironmentalChange Institute at the University of Oxford wasquite clear when appearing before a House ofLords Select Committee12:

"We have looked at that [stationaryanticyclones in the middle of winterover the British Isles] occurring in thewind data and the wind data doesnot show it."

Several authors, including National Wind Power,have also found that peak demand periodsactually tend to coincide with above-averagewind plant output13. The reason for this is thatwind output will tend to be correlated to periodsof high peak demand, as one of the key factorsin determining the load on the electricity systemis wind speed. Cold, windy days will lead toincreased demand for heating.

Additional balancing costsThese costs also tend to be controversial, but aclose examination of the evidence shows thatthere is actually a very good measure ofagreement between several studies. Modestamounts of wind cause few problems (or costs)for system operators, as the extra uncertaintyimposed on a system operator by wind energy

Figure 5: Capacity values from three UK studies

Note: Capacity values are shown divided by capacity factors to normalise the data, as differentcapacity factor assumptions have been used in each study.

NGC SCAR CEGB

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 5 10

Wind output as percentage of total (%)

Capa

city

val

ue /

ann

ual c

apac

ity

fact

or

15 20 25



is not equal to the uncertainty of the windgeneration, but to the combined uncertainty ofwind, demand and thermal generation.

The characteristics of most electricity systemstend to be similar, so estimates of the extrareserve needed to cope with wind energy arealso similar. With wind supplying 10% of theelectricity, estimates of the additional reservecapacity are in the range 3 to 6% of the ratedcapacity of wind plant. With 20% wind, therange is approximately 4 to 8%. Estimates of the‘additional costs of intermittency’ are mostlyclose to National Grid’s figures: accommodating10% wind on the UK system would increasebalancing costs by £40 million per annum(£2/MWh of wind), and 20% wind wouldincrease those costs by around £200 million perannum (£3/MWh of wind). Estimates from otherstudies, including work by or for PacifiCorp, theBonneville Power Authority and the Electric

Power Research Institute yield similar results,shown in Figure 6. With 5% wind, the extracosts are within the range $1.7-3/MWh, andwith 10% wind the range is $3-5/MWh.

Plant margin and load factorsThis is best addressed by looking at how windcapacity fits into the electricity system, usingdata relevant to the UK network in 202014:

Peak demand (in 2020): 70 GWInstalled capacity: 84 GWPlant margin: 20%Total generation: 400,000 GWhSystem load factor: 54%

When 26 GW of wind is installed on the systemit will displace 5 GW of conventional generation(see above), so the installed capacity becomes:

Figure 6: Estimates of additional balancing costs from six studies

NGC Ilex PacifiCorp BPA (Max) BPA (Min) EPRI/XCEL GRE

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 2 4 6

Wind output as percentage of total (%)

Cost

of

addi

tion

al b

alan

cing

($/

MW

h)

8 10 12

⇒ 84 GW – 5 GW + 26 GW = 105 GW



So, the apparent plant margin is higher, at 50%. However, this arises simply because the load factor(capacity factor) of wind is lower than that of conventional plant and it is therefore debatable whetherthe apparent margin of 50% is very meaningful. In effect, 5 GW of conventional plant will have beenretired (compared against a baseline scenario), so although the 26 GW of wind capacity will not havedisplaced an equal amount of conventional plant, it will have displaced some, and only a modestamount of additional thermal capacity will be required to cope with the additional variability of windoutput. This additional reserve capacity is not the same as additional thermal plant, and is most likelyto be provided by a small increase in the remaining plant (that which hasn’t been displaced by thecapacity value of wind) running in ‘reserve mode’ or an increase in the use of storage or demandmanagement. In common with many of these issues, this represents a cost to wind rather than aserious constraint.

A side effect of adding 26 GW of wind is that the load factor of the remaining plant is depressed. Theoverall load factor was 54% before wind capacity was added. When 26 GW of wind capacity isincluded, the new load factor is calculated as follows:

As the load factor of the remaining conventional plant is now seven percentage points lower, thisimplies that the generation cost of this plant increases, as the annual capital repayments are spreadover less output. This is another ‘system cost’ that results from adding substantial amounts of windcapacity and is also considered as part of system costs in Chapter 4.

It should be noted, however, that the introduction of any new plant into an electricity network tends todepress the load factor of the existing plant. If, instead of 26 GW of wind, 10 GW of new nuclearcapacity were installed (which would generate the same amount of electricity if it operated with a87.5% load factor), this would displace 8.75 GW of thermal plant. The load factor of the remaining gasplant would then be:

(total generation – wind generation) / ( (installed capacity-wind capacity value) x hours in year)

⇒ (400,000 GWh – 77,000 GWh) / ( (84 GW – 5 GW) x 8,760 hours)

⇒ 323,000 / 692,040 = 47%

⇒ ( (400,000 GWh – 77,000 GWh) / ( (84 GW – 8.75 GW) x 8,760 hours)

⇒ 323,000 / 659,190 = 49%

Once again, the load factor has been reduced, although by a smaller amount. Strictly speakingtherefore, the additional costs of operating a system with wind energy should not include the costsassociated with reducing the load factor of the gas plant by 7% (54-47%), but by the additional loadfactor reduction, compared with the introduction of new conventional plant. With the numbers usedabove, this corresponds to a 2% reduction. The analysis in Chapter 4 implicitly factors in the additionalcosts associated with an 7% reduction, and is therefore likely to overestimate this cost element.

It should be emphasised that this additional reduction of the load factor of remaining plant only appliesat high wind energy penetrations, when the capacity factor of the wind plant is greater than its


capacity value. At low wind energy penetrations(below about 6%), the capacity value is equal toor greater than the annual average capacityfactor. In this case, the extra costs associatedwith the reduced load factor of the incumbentplant are similar to, or less than, thoseassociated with introducing new thermal plant.No extra system costs are therefore due to wind.

A critique of the E.oN Netz studyA recent report from the German networkoperator E.on Netz, ‘Wind Year 2003 – anoverview’, appears to suggest that capacityvalues are much lower, and additional balancingcosts much higher, than the figures quotedabove. The report also highlights a low energyproductivity of German wind. It claims that theutility needs reserve capacities amounting to50-60% of the installed wind power capacity,and that the extra balancing costs (for 6% wind)were about €12/MWh of wind – over six timesthe estimates of Figure 6. On closer inspection,there appear to be several reasons why thenumbers are quite different from the‘consensus’ data discussed above.

Firstly, low wind speeds in Germany mean thatthe system operators will experience morefluctuations in wind output than in windierregions. To illustrate this point, assume that theaverage capacity factor across Germany is 15%and the corresponding capacity factor in Britainis close to its long-term average of about 30%.To generate 8.5 TWh of wind in Germanyrequires 6250 MW of wind plant, whereas onlyhalf that amount of plant would be required inBritain. The power swings from 6250 MW ofGerman wind would therefore be higher thanfrom 3125 MW of wind in Britain.

Secondly, it appears that some of the apparentdifficulties the utility has with wind are more todo with administrative procedures and barriers;the network operators tend to operate

independently, so some of the benefits of anintegrated network are lost.

Thirdly, plant commitments are made severalhours ahead, and the extent to which schedulesare revised nearer to ‘real time’ is not clear. Theconcept of a ‘one hour gate closure’, as in GreatBritain, or revising a schedule up to one hourbefore production, appears not to be used.

It may also be noted that the report does notdiscuss the all-important question of theinteraction between variations in consumerdemand and variations in wind output.

Future costsThe wind industry has delivered impressivereductions in cost and productivity over the pasttwenty years. Energy generation prices, as aresult, are now close to those of the fossil fuels.

Cost are expected to continue falling for threereasons:

• Experience: If wind energy capacity continuesto double every three to four years,accompanied each time by a 15% reduction inwind turbine production costs, there will be a20% reduction in installed costs by 2010. Theconsensus of the many studies is consistentwith this simple analysis, as shown in Table 2.

• Larger wind turbines: The trend towardslarger wind turbines shows no sign of abating,bringing with it reduced project costs fromsavings in foundations, transport and electricalconnections – even though the wind turbinesmay be slightly more expensive per kilowattof rated capacity.

• Larger wind farms – especially offshore:The trend towards larger wind farms bringssavings in the construction phase, in projectmanagement, more efficient utilisation ofheavy lifting equipment and, not least, in grid




connection costs. Increases in project size donot lead to a proportional increase in gridcosts, which depend on the length of newlines required and the costs of transformersand switchgear. A number of detailedanalyses of future trends in wind energy costshave been carried out recently. Some havebased their projections on ‘learning curvetheory,’ looking at the way costs have fallenwith increased production; others have lookedat the engineering aspects of both windturbines and wind farms.

Data in Table 2 suggests installed costs onshorewill drop by between 11% and 23% by 2010compared with 2003, giving a range ofestimates for onshore installed costs in 2010between €770-870/kW (£530-600/kW). The corresponding range for 2020 is around£450-620/kW, setting aside the EWEA study,which appears rather low.

Offshore costs are expected to fall somewhatfaster as the industry gains more experience inthis sector. By 2010, the studies suggest thatoffshore project costs will be down by 27% to37%, giving a range of around £700-800/kW.By 2020, they may fall further to around £600-700/kW.

Generation costs are expected to fall a littlefaster as the larger machines capture higherwind speeds.

Although there is some uncertainty over futurecosts, it may be noted that the price of electricityfrom wind plant is effectively fixed once the plantis constructed (setting aside interest ratevariations). By contrast, the future prices of fossilfuels are very uncertain and can cause the priceof electricity to change after the plant isconstructed (unless long-term fuel contracts canbe secured, which is unlikely in the presentclimate). Future prices of gas are extremelyuncertain and it is suggested that the premium

Source 2010 cost,2020 cost (€/kW)

(2010 cost)/(2001 cost)

(2020 cost)/(2001 cost)

Notes

EWEA15

Forum for theFuture16

Report for US DoE17

UK, PIU18

UK, DTI19

Garrad Hassan20

Australian study21

451,363

-,443-590

0.77

0.63

0.5-0.7

0.89

0.73

0.63

0.70

0.58

0.69-0.92

Down to ~0.6

Down to ~0.4

0.81

0.57

0.55

Installed costs onshore

Installed cost onshore

Installed cost offshore

Installed costs onshore

Generation costs onshore

Generation costs offshore

Generation costs offshore

Installed cost onshore, ref 2003

Installed cost offshore, ref 2003

Generation costs onshore

Table 2: Estimates of future wind costs(In the second and third columns, costs are expressed as ratios, so Forum for the Future suggests that2010 costs onshore will be 77% of 2001 costs.)


needed to "guarantee" fixed gas prices over a 10-year period is around 0.5 USc/kWh. so theemphasis in the short term may well be on coal.22

The uncertainty over future fossil fuel prices andthe continuing downward trend in wind energyprices means that the outlook for wind energy isbright. Wind is already competitive with gas andcoal on the higher wind speed sites and thisadvantage is likely to be strengthened in thefuture. By 2010 – possibly earlier – theinstallation of wind energy may well result inlower costs to electricity consumers comparedwith the continued exploitation of the fossilenergy sources.

Fault ride-through considerationsThe characteristics of the synchronousgenerators used in large conventional thermaland hydro units enable the plant to contribute tothe provision of system support services (e.g.dynamic voltage and frequency regulation) thatare necessary for the stable operation of thesystem. Wind turbines use different generatortechnology and, at the moment, do not providea similar range of support services to thesystem. At relatively low levels of wind energypenetration this can be tolerated. However,operating the system with large amounts ofsuch plant would pose major challenges interms of sustaining system integrity.

Hence, the GB Transmission Network Operatorshave recently set out a proposal that specifiesrequirements for connecting wind generationequipment to the transmission network. Theseproposals are described in the Grid Codeconsultation document.23 Similar Grid Codemodifications have been made in a number ofother countries with high penetrations of windenergy24/25.

The main capabilities required of wind farms inthe proposed GB Grid Code modifications are:

1. Reactive power capability

2. Active voltage control

3. Restricted maximum ramp rates

4. Operation over an extended frequency range

5. Frequency control capability

6. Power System Stabiliser function

7. Fault ride-through capability

Because of the requirement to provide dampingin their mechanical drive trains, wind turbinescannot use directly connected synchronousgenerators such as are universally used in largeconventional power generating units.26 Fixedspeed wind turbines use directly connectedinduction generators while variable speed windturbines use power electronic converters toconnect the fixed frequency of the powersystem to the variable frequency of thegenerators. This variable frequency performanceis achieved using either the so-called DoublyFed Induction Generators (DFIG) or generatorsfed through two fully rated power electronicconverters. Traditionally smaller wind turbines(up to around 1 MW) have used fixed speedinduction generators with larger wind turbinesusing DFIG technology. However, in the futurethere is likely to be an increasing move to fullyrated power converters.

The requirements of the new GB Grid Codescannot be met by fixed speed induction generatorwind turbines without additional equipment toprovide fast control of reactive power (i.e. StaticVar Compensators – SVCs or STATCOMs). It isbelieved that DFIG and fully rated converterdesigns can, in principle, meet these requirementsbut at some additional cost. Following consultationwith manufactures, NGC estimated the additionalcost of meeting the GB Grid Code requirements as



being between 1.4%-6% of turbine capital cost.However, such information is commerciallyconfidential and difficult to verify. The proposedGrid Code modifications are still underconsideration by OFGEM and so far evidence ofcompliance by operating wind farms with all theGrid Code provisions has not been published inthe open literature.

A particular concern of Transmission NetworkOperators is the ability of generators to remainstable and connected to the network whenfaults occur on the transmission network. This isknown as fault ride-through capability.

Faults are inevitable on any electrical systemand can be due to natural causes (e.g.lightning), equipment failure or third partydamage. With relatively low transmission circuitimpedances, such fault conditions can cause alarge transient voltage depression across widenetwork areas. Conventional large synchronousgenerators are expected to trip only if apermanent fault occurs on the circuit to whichthey are directly connected. Other generatorsthat are connected to adjacent healthy circuitsshould remain connected and stable after thefaulted circuits are disconnected. At present, theGB transmission system is operated to withstanda maximum sudden loss of 1320 MW (i.e. two660 MW generators).

However, if generation connected to healthycircuits does not remain connected and stableduring and after the fault, this generation willbe lost in addition to that disconnected by theoriginal fault. Clearly, in this case the powersystem would be exposed to a loss ofgeneration greater than the current maximumwith the consequent danger of the system

frequency dropping too rapidly and loadshedding becoming necessary.

A number of studies27 have been carried out todetermine the depth of the propagation ofvoltage depressions for various fault locationsand generation scheduling patterns.iii These havethen been used to demonstrate the risk to thesystem of connecting wind turbines which arenot adequately robust and which, whileconnected to healthy circuits, will trip for remotefaults.

In summary, if the wind generation to beconnected is not able to ride through faults in asimilar manner to conventional synchronousplant, the power system would be exposed to aloss of generation greater than the currentcredible maximum. In this context, the proposedGrid Code update to incorporate wind generationis based on the fundamental requirement thatthe maximum largest loss of generation shouldnot exceed 1320 MW. This effectively requiresthat wind generation must remain connectedand be able to ride through faults on thetransmission network.

Similar fault ride-through requirements arespecified in most countries with large numbersof wind turbines including Germany, the world’slargest wind turbine market. Unfortunately, thedetailed requirements of voltage level andduration of the fault often differ from country tocountry and there is a clear need forharmonisation, if the operational requirementsof the individual power systems allow this.However, given the universal requirement byTransmission System Operators for fault ride-through capability, it is likely that this will beprovided as a standard feature of large windturbines in the future.


iii A factor to be considered is the amount of wind generation connected, as this may have an impact on the actual level oftransient voltage at the terminals of the generator due to voltage difference between the fault and the wind farm.


References

1 Grevensberg. Verlag Naturliche Energie. Windkraft Journal.

2 Bergey, K H (1991). Windfarm strategies: the economies of scale revisited. Proc Windpower ’91, Palm Springs, 24-27September. American Wind Energy Association.

3 European Wind Energy Association (2004). Wind Energy – the facts.

4 Kassel (2004). Wind Energy report. Annual evaluation. ISET.

5 Milborrow, D J (2005). Goodbye gas and squaring up to coal. Windpower Monthly, 21, No 1, (Jan).

6 Harrison, L and Milborrow, D J (2002). In the absence of a carbon tax. Windpower Monthly, 18, No 4, (April).

7 British Wind Energy Association (1982). Wind energy for the eighties. Peter Peregrinus Ltd, Stevenage.

8 Holt, JS, Milborrow, DJ and Thorpe, A (1990). Assessment of the impact of wind energy on the CEGB system. Report forthe European Commission.

9 Milborrow, D (1996). Capacity credits – clarifying the issues. British Wind Energy Association, 18th Annual Conference,Exeter. Mechanical Engineering Publications Ltd, London.

10 Carbon Trust & DTI (2004). “Renewables Network Impact Study” Annex 4: Intermittency Literature Survey & Roadmap.

11 National Grid Transco (2003). Evidence to: House of Lords, Science and Technology Committee, 4th report, Session 2003-04. Renewable Energy: Practicalities. HL paper 126-II.

12 Sinden, G (2004). Oral evidence to: House of Lord Science and Technology Committee. Renewable Energy: Practicalities.HL paper 126-II.

13 Warren, J G, Hannah, P, Hoskin, R E, Lindley, D and Musgrove, P J 1(995). Performance of wind farms in complex terrain.Proc 17th BWEA Wind Energy Conf. Warwick, MEP Ltd.

14 Dale et al. (2003). Total cost estimates for large-scale wind scenarios in UK. Energy Policy 32, pp. 1949-1956.

15 European Wind Energy Association (EWEA) (undated 2001 or 2002). Wind force 12: A blueprint to achieve 12% of theworld’s electricity from windpower by 2020.

16 Ekins, P (2001). The UK’s transition to a low-carbon economy. Forum for the Future.

17 Osborn, J et al. (2001). A sensitivity analysis of the treatment of wind energy in the AEO99 version of NEMS. University ofCalifornia/National Renewable Energy Laboratory, LBNL-44070.

18 UK Cabinet Office (2002). Performance and Innovation Unit. The Energy Review.

19 DTI (2002). Future offshore. A strategic framework for the offshore wind industry.

20 Garrad Hassan and Partners (2003). OFFSHORE WIND:Economies of scale, engineering resource and load factors. Dept ofTrade and Industry / Carbon Trust.

21 Mallon, K and Reardon, J (2004). Cost Convergence of Wind Power and Conventional Generation in Australia. Report forthe Australian Wind Energy Association by Transition Institute P/L.

22 Bolinger, M, Wiser, R and Golove, W (2002). Quantifying the value that wind power provides as a hedge against volatilenatural gas prices. Proc Windpower 2002. American Wind Energy Association.

23 National Grid Company plc, Scottish Hydro-Electric Transmission Ltd, Sp Transmission Ltd (2004). Background to proposedchanges to England & Wales and Scottish Grid Codes Connection Conditions to Incorporate Non-synchronous GenerationTechnologies. Supporting Paper for NGC Consultation H/04 and SHETL & SPT consultation SA/2004, 23 June 2004.

24 EoN Netz (2003). Grid Code for extra-high and high voltage.

25 ELTRA (2000). Specifications for connecting wind farms to the transmissions network. ELT1999-411a, April 2000.

26 Jenkins, N., Allan, R., Crossley, P., Kirschen, K., Strbac, G. (2002). Embedded Generation. IEE, London.


References

27 National Grid Company plc, Scottish Hydro-Electric Transmission Ltd, Sp Transmission Ltd, Background to proposed changesto England & Wales and Scottish Grid Codes Connection Conditions to Incorporate Non-synchronous GenerationTechnologies, Supporting Paper for: NGC Consultation H/04 and SHETL & SPT consultation SA/2004, 23 June 2004;Integrating Renewables and CHP into the UK Electricity System, Tyndall Centre for Climate Change Research Project TC/IT1.30; An Investigation of the Impact of Renewables and CHP on the GB Central Generating System, X. Wu, N. Jenkins, G.Strbac, The Manchester Centre for Electrical Energy, UMIST, 2003


Types of radarPrimary surveillance radar (PSR) usuallyconsists of an antenna constantly rotatingthrough 360º round the horizon, sending outpulses of electromagnetic energy that reflect offany object in their path. The reflected energytravels back to the radar antenna where theangle from which the reflection was receivedand the time taken for the pulse to travel outand back are translated into bearing and rangefrom the radar and displayed on a controller'sscreen.

Secondary surveillance radar (SSR) sends outpulses from a constantly rotating antenna (ofteninstalled on top of a PSR antenna) but in thecase of SSR these are interrogation signals thattrigger responses from transponder equipmentin aircraft. The response includes a four-digitcode (set by the pilot) which identifies theaircraft, together with the height of the aircraft.(The height derived by SSR is electricallygenerated and is not always a true and accuratereflection of the actual height of the aircraft).This information is then displayed on the radardisplay next to the radar 'blip'. The maindifferences between PSR and SSR are:

a) PSR will detect any reflecting object, whereasSSR will only display returns from aircraftwith their transponders switched on.

b) PSR cannot determine the height of anobject; in most cases SSR can. The onlyexception to this is air defence radars, whichare 3D, and can determine the height of anobject using PSR only.

Effects on PSRSignal processing is employed in PSR so thatobjects which are not moving (such as hills,buildings and trees) or are moving at speedsmuch slower than aircraft (such as ships and

road traffic) are not displayed on the screen.This is called Moving Target Indication (MTI)processing. However wind turbines present aparticular problem. They remain in one location,but their blades are turning with tip speeds ashigh as 150 knots – similar to aircraft speeds. Sonormal MTI processing cannot eliminate radarreturns from wind turbines and the turbines arelikely to appear on radar. Controllers have toaddress:

• Lack of a reliable means of telling whether aprimary radar return from the wind farm areais a turbine or an aircraft. This may require thecontroller to assume the return is an aircraft,and to ensure that the aircraft to which he isproviding a service avoid this unknown return.

• The radar returns from the wind turbines mayobscure genuine returns from aircraft flyingover the wind farm. This could lead touncertainty that the radar can detect all non-cooperating aircraft in that area.

• The wind turbines may create a radar'shadow' behind them, within which theradar's ability to detect aircraft may bereduced.

Radar is capable of seeing some way beyondthe horizon compared to the visual line of sight.This is because a radar beam refracts, or bends,to some extent towards the earth as it travelsthrough the atmosphere. Radars may be able todetect high-flying aircraft up to 200 nauticalmiles (370km) away. Objects at lower altitudes,such as wind turbines, may be capable ofdetection 100km away or more, particularly ifthe radar and the wind farm are located onprominent hilltops.

There are three uses for primary radar inaviation – each of these has particularrequirements and specific issues in terms of thepotential impact of wind turbines.

Annex CAviation and communication


Effects on SSRBecause SSR operates on the basis oftransmissions both from the radar to the aircraftand from the aircraft back to the radar, thereturned signal is much stronger than in thecase of PSR. It is therefore much less vulnerableto interference from wind turbines. Beamdistortion, caused by scattering of the signal bythe wind turbines and leading to target positionerrors or false interrogations, is another effect.

Studies in the Netherlands, Ireland and the UKhave found that wind turbine effects on SSR arenegligible for a wind farm located 5km or morefrom an SSR station. NATS En Route, whichoperates SSR at all of its radar stations (repeated)is also notable that the impacts of wind turbineson SSR have been found to be generated by theturbine towers, not the rotating turbine blades. Inthis respect the impact of wind turbines on SSR isno different in form to that of other tall structuressuch as chimneys or high buildings.1

ATC around airfieldsMost military airfields and commercial airportsare equipped with PSR, which is used bycontrollers to guide aircraft after take-off, toguide incoming aircraft to the runway, and tomaintain separation for aircraft operating in thevicinity of the airfield.

For these radar systems, a wind developmentlocated beneath the departure track or the finalapproach track, or in an area where aircraft arefrequently routed (vectored), may createparticular problems for controllers. Aircraftvectored across the wind farm area may not bedistinguishable from the radar returns producedby the wind turbines. Depending on the level ofradar service being provided, aircraft may haveto be vectored away from the radar returnsproduced by the wind turbines.

This can result in aircraft having to fly longerdistances, inability to maintain the standardseparations between aircraft and, in severecases, may preclude the provision of a radarservice altogether.

These difficulties are most likely to occur whenthe wind farm is located in uncontrolledairspace, that is, airspace where any aircraft mayfly without obtaining permission from ormaintaining contact with any ATC agency. This isbecause in this type of airspace it is more likelythat an unknown primary radar return – forexample from a wind turbine – could be a realaircraft, and therefore may require radarcontrollers to vector aircraft around it. Mostmilitary airfields and the smaller civil airportsand airfields are in uncontrolled airspace.

Airport radars typically provide services out to arange of approximately 40nm (74km) but anyimpacts from wind farms are likely to be limitedto projects within a significantly closer range.Statutory safeguarding arrangements are inplace around most commercial airports. Most ofthese require pre-planning consultation for anywind farm proposal within 30km. However,objections from airport operators may beencountered at greater ranges when the windfarm is in a key area of ATC operational interest.In addition, because responsibility for civilairport safeguarding has been transferred fromthe central regulatory authority, the CAA, toindividual airports, policy and practice on windfarms can vary significantly from one airport toanother.

En route ATCControl of aircraft in the en route phase of flightis carried out by controllers employed byNational Air Traffic Services (NATS), based at fourcentres at Swanwick, West Drayton, Manchesterand Prestwick. In addition, en route controllersprovide radar services to military aircraft, often

Annex C: Aviation and communication


in uncontrolled airspace, where the impact ofunidentified primary radar returns from windturbines is more significant.

En route radars may be able to detect windturbines 120km or more away from the radarhead. The resulting areas within which windenergy projects may be restricted are very large.Projects in the north of England, southernScotland and eastern Wales are particularlyvulnerable due to the location of three keyhilltop radar stations in these areas. NATS hashad difficulty in achieving timely handling of thevolume of pre-planning notifications of windfarm projects and in late 2004 introduced a newprocedure whereby developers are encouragedto consult web-based maps of NATS areas ofconcern to determine whether a NATS objectionis likely. In relation to some en route radar, themaps show areas of interest extending to asmuch as 100nm (185km) from the radar station.

This may be because the wind farm is locatedwholly within controlled airspace, or is in anarea of relatively low traffic density, or becausethere is overlapping radar cover from anotherradar which is not capable of illuminating thewind farm.

Air defence radarAir defence radars employ both primary (PSR)and secondary surveillance radar (SSR) in thesame way as ATC radars, but air defence radarsgenerally have more sophisticated trackingability and their primary radars are also able todetermine the height of a target without SSRinformation.

Since September 11th 2001 the Ministry ofDefence has become more concerned about theimpact on the air defence radar system ofspurious radar returns from wind turbines andhas adopted a policy of raising concerns aboutany wind farm within line of sight of an air

defence radar head. The air defence authoritiesrequire reliable coverage of the low levelairspace over both land and sea, so overheadobscuration, induced tracking anomalies andshadow effects are currently of most concern tothe air defence community.

However, as experience has been gained, someprojects within direct line of sight of the radarshave been approved following re-assessment oftheir specific impact, taking into account anyexisting wind farms in that sector of the radar'scoverage, the importance of the area for airdefence, the solidity and reliability of the radar'scover in that area, and whether there isoverlapping radar cover from another radarwhich is not capable of illuminating the windfarm.

Mitigation measuresOperational measuresIncreasing controlled airspace can significantlyreduce the impact of wind turbines on radar.This is because all aircraft require air trafficcontrol permission to enter controlled airspace.By definition, primary-only radar returns fromlocations inside controlled airspace where thereare no known aircraft can be assumed bycontrollers not to be aircraft. There may still beconcerns, however, about the cumulative impactof multiple wind farms and about the effects ofprimary radar clutter from wind farms on theability to track aircraft across the wind farmarea. It is also important to note that controlledairspace is not established in order to mitigatethe impact of wind farms; it can only beinstigated when justified by the levels and typesof air traffic. It is typically applied aroundairports with significant levels of commercial airtransport flights.

Avoiding areas of significant air traffic controlinterest for wind farms within an airport's radarcoverage. Typically, avoiding the final approach



and departure areas for the main runways isessential. In addition, some airports will have airtraffic flows biased in particular directions (atairports in Scotland and Northern Ireland, forexample, most commercial traffic is to/from thesouth and south east); wind farms located awayfrom those flight paths will have more chance ofavoiding aviation objections.

Introduction of Mode S secondarysurveillance radar – a new form of SSR which isbeing progressively introduced across Europe.The ultimate plan is for all aircraft to be requiredto carry and operate a Mode S transponder forall flights in all types of UK airspace from 31March 2008. This proposal is subject toconsultation with the UK aviation industrycommencing in 2005. Mode S offers theprospect of a significant change in the impact ofwind turbines on air traffic radar services. This isbecause, at present, many aircraft, mainly lightaircraft, gliders, microlights and otherrecreational aviation, fly without a transponder.These aircraft appear as primary-only returns onradar and, due to their small size andconstruction materials, even their primary radarreturn may only appear intermittently. Becauseany primary radar return could be one of thesecategories of aircraft, controllers providing aservice in uncontrolled airspace currently mustassume that any primary-only return is anaircraft. If all aircraft from 31 March 2008 mustlegally be transmitting a Mode S transponderidentity, this offers the prospect of a change inregulatory policy on the action to be taken bycontrollers when they see a primary-only returnon their radar screen. If a primary-only returncannot be an aircraft flying legally, these returnscould be assumed not to be aircraft. This wouldbring to an end the need for controllers tovector aircraft around primary radar returnsgenerated by wind turbines. No proposals onchanges to the policy on treatment of primary-only radar returns in a mandatory Mode S

environment have yet been put forward by theCAA.

Limiting the radar service in uncontrolledairspace is an option open to controllersproviding a service to aircraft in uncontrolledairspace. This is frequently used by controllerswhen clutter, whether generated by weather,road traffic, wind turbines or other sources, ispresent on the radar screen. Although a fully-approved and routinely-used procedure, it doesconstitute a degradation of the radar serviceoffered.

Technical measuresRange-azimuth gate mapping (RAG mapping)is a technique routinely applied in primaryradars which identifies particular elements ofthe radar's coverage within which returns aresuppressed. It is often used to eliminate cluttercaused by road traffic and buildings. It haspotential for use in eliminating wind turbinereturns but has the major disadvantage that italso suppresses returns from any aircraftcrossing that area, thereby creating a hole in theradar cover and degrading the service providedto pilots.

Temporal threshold processing sets the radar'ssensitivity in particular parts of its coverageaccording to the amplitude of the signalreceived from that area. This reduces the radar'ssensitivity when particular 'cells' are producinghigh levels of clutter. This process is quiteeffective in removing shifting clutter returnsfrom the radar screen. However, if a desiredtarget within the area has a weaker return thanthe clutter, or if it stays within the area forseveral antenna sweeps (as for example ahovering or slow-moving helicopter might), theclutter threshold will eliminate that genuinetarget as well as the clutter.



Clutter maps deal with clutter by storing thelocation and other characteristics of clutter in amemory circuit, which is then accessed on eachsweep to remove that clutter from the signal.Some radars have numerical limits on thenumber of cells which can be used for cluttermapping or RAG techniques. This may limit theapplicability to multiple wind farms.

Track processing analyses radar returns andrejects any consecutive returns which do notconform to pre-set criteria for a moving aircraft.UK radar manufacturer AMS is currently triallingequipment known as ADT which uses a novelapproach to track processing which it is hopedwill eliminate wind turbine returns and also gainapproval from the CAA.

Placing antennea at an elevation that raisesthe radar beam above the wind farm. In somecases it may be possible to eliminate windturbine returns from radars where the antennaelevation above the horizontal raises the radarbeam above the wind farm. The radar antennaat Belfast Airport, for example, is raised to avoidclutter from local high ground, which hasresulted in it avoiding returns from the nearestwind farm. However it is unlikely that raising ofan antenna specifically to avoid wind turbinereturns would be acceptable in most cases sinceit would cause reduced coverage of low levelairspace.

Optimised antenna design for low elevationsidelobes, adjusting the tilt of the transmittedand received beams to minimise the number ofunwanted returns in the lowest elevation beam,changes to signal processing to reduce the preand post-compression limiting anddesensitising the background averager are asyet unproven and yet to be implemented.Ongoing trials and the DTI-funded AMSFeasibility Study which should be published inJune 2005 aim to specifically identify and

evaluate technical software and hardwaremitigation techniques which will then beassessed by the MOD.

Radio navigation aidsAeronautical radio navigation aids – beaconsto assist aircraft in determining their location –are also potentially vulnerable to interferencefrom wind turbines. Most aeronautical radionavigation aids in the UK are operated by NATS.All NATS technical sites have statutoryconsultation status for wind farm and otherdevelopments in close proximity. For all types ofbeacon – VOR, NDB, DME – the safeguardingzone for proposed wind energy developments isa 10km radius around the facility.

Although there is some evidence fromelsewhere in Europe that safeguarding zonesaround radio navigation aids are smaller than inthe UK, there is no evidence of UK safeguardingpolicies around these types of facility restrictingwind farm development.

Television interferenceBroadcast transmissions and the fixed radio linksare vulnerable to multi-path effects in the sameway as any radio. Television pictures and soundare fed to the transmitters by a network of fixedradio links, the higher capacity ones operating atmicrowave frequencies (3-30 GHz) while the re-broadcast links (RBLs) from main to localtransmitters operate in the lower capacity UHFband (0.3-3 GHz).

Three way split of responsibilityResponsibility for maintaining the quality oftelevision signals across the UK is splitgeographically between the BBC and what usedto be known as the Independent TelevisionCommission (ITC), now integrated into the Officeof Communications (Ofcom). Responsibility forthe integrity of the supporting network of



transmission links is correspondingly splitbetween two companies – Crown CastleInternational (CCI) and NTL.

Because wind farms are usually situated inrelatively sparsely populated areas, the numbersof people affected are usually small. There isnow extensive experience in the industry ofwind farm developers entering into planningagreements to fund studies of TV receptionquality and any mitigation required. This cantake the form of installation of more sensitivereceiver antennae for individual subscribers;moving antennae to receive from a differentsource transmitter; or installing a localcommunity re-broadcast facility.

The fixed microwave and UHF transmissionnetwork can present more widespread issues forwind energy developments. These travel instraight lines between two fixedtransmitter/receiver points. Vulnerability tomulti-path effects is determined by thefrequency of the signal and the length of thelink path. The lower the frequency and thelonger the link, the more risk there is of multi-path effects. Consequently, long-distance links atUHF frequencies require much larger clearancezones than short microwave links.

In 2002 the Radiocommunications Agency – nowpart of Ofcom – produced a methodology forcalculating the minimum separation distancebetween a radio link and a wind turbine, usingas its basis the concept of the Fresnel Zone2. Asan example, the Ofcom formula calculates that a20km long microwave link at 7 GHz wouldrequire a clearance of 21 metres between thecentre of the link path and any part of a windturbine at the midpoint of the link, but a smallerclearance towards either end. At 2 GHz,however, the same link would require 39 metresclearance.

As can be seen from the example above, theOfcom recommended clearances are relativelysmall, and would permit constructing a windfarm directly in the path of a microwave link ifthe turbines were placed to avoid the calculatedFresnel Zone.

The consultation process for potential wind farmimpacts on television is well-established butbecause of the split responsibilities between theBBC, two parts of Ofcom, Crown Castle and NTL,it lacks integration. Ofcom licenses most fixedradio links in the UK and this covers some of thetelevision transmission network. However theyare not responsible for UHF RBLs. It is thereforenecessary to consult all four television bodiesplus the fixed link department of Ofcom toobtain an assessment of the likely impact of awind farm proposal on television. There is alsouncertainty derived from differences in policy onthe response to consultations. Some of thetelevision consultee organisations will providepreliminary pre-planning assessments whichenable developers to assess project risk at anearly stage. Others provide no response untilafter a planning application is submitted.

Ofcom recommendations not alwaysfollowedThe problem, however, is that thetelecommunications industry, includingtelevision broadcasters, have not generallytaken up the Ofcom recommendations. This isbecause of a number of uncertainties about theprecise effects of wind turbines on radio links,notably:

• The potential for more complex multi-patheffects to occur in multiple-turbine wind farms

• A belief that the Ofcom formula is atheoretical minimum and that engineeringpractice ought to build in a 'buffer' to takeaccount of uncertainties



• In many cases, lack of precision in the locationdata for transmitter and receiver sites, leadingto large buffer zones around radio links toaccount for inaccuracy

UHF re-broadcast linksFor UHF re-broadcast links (RBLs) carrying the TVsignal from main to local transmitters, theproblem is of a larger magnitude. Unlike amicrowave signal, whose beam is very narrow,the transmitted UHF signal takes the form of awide cone. The receiver is capable of picking upvery low signal strengths at the other end, butbecause of the wider area over which the signalis transmitted, it is more prone to multi-patheffects. The vulnerability is greatest when thereflecting object is close to the receiver end ofthe link both in distance and in angle.Experience in the TV industry has been that ifthe angle between the RBL receiver totransmitter path and the receiver to wind farmpath is less than 15º, effects are likely and thereare no feasible mitigation measures other thanmoving the RBL receiver mast to a new locationor installing a new microwave link which'doglegs' around the wind farm. At anglesgreater than 15º there is some potential formitigation measures such as installing a moredirectional receiving antenna at the RBL receiverstation. At angles greater than 60º there shouldbe no effects on TV signal quality.3 Industryexperience has also found that no effects shouldbe expected when the wind farm is 10km ormore away from the RBL receiver.

The difficulty for wind farm developers is that, ifa project falls within the 15º zone from an RBLreceiver, mitigation is expensive. A newmicrowave link, or the relocation of the RBLreceiver, is likely to cost several hundredthousand pounds, and may delay the projectconsiderably while engineering planning, siteselection, land purchases and further impactassessments are carried out.

Potential constraints on wind energydevelopment from television RBLs are alsoexacerbated by topographical realities. RBLs aremost prominent in hilly areas because this iswhere the main transmitter signal cannot reachsubscribers, mostly located in valleys. RBLstherefore frequently cross areas of good windresource.

Technological trendsTechnological trends are changing thetelecommunications environment. As thedemand for greater and greatertelecommunications capacity grows, there is amove away from older systems operating atlower frequencies towards higher frequencies.This benefits wind energy development sincehigher frequency systems do not require suchlarge obstacle-free zones around their paths.Many communications networks are movingaway from fixed terrestrial radio linkscompletely, to other technologies such assatellite and fibre-optic cable. There is also atrend from analogue to digital systems – again apositive trend for wind energy because digitalradio is generally more robust in terms of itssusceptibility to interference. The developing 3Gmobile phone network may generate additionalconstraints on wind energy projects, but this isnot because of the potential impact on signalsto/from mobile phones themselves. It isbecause 3G technology requires more basestations than existing mobile phone systems.This will mean more fixed radio links to/frombase stations.

Fixed radio linksMost of these links are at microwavefrequencies (3-30 GHz). The Ofcom-recommended wind turbine clearance zonesaround microwave links are relatively narrow.However most microwave link operators havenot taken up the Ofcom recommendations forthe same reasons as outlined above.



The consultation process for wind farmdevelopers investigating potential impacts onfixed microwave links is even more fragmentedthan for the television industry. The first point ofcontact is Ofcom's fixed links department.However Ofcom's database is notcomprehensive. Several significant operators,including BT, the CAA and the MOD, are notcovered, and the pace of development bymobile phone companies in particular can meanthat many new links take some time to enterthe Ofcom database. A response of 'no knownlinks' from Ofcom therefore cannot be taken asdefinitive and it is necessary to contact allindividual operators direct. This is compoundedby the complexity of contractual arrangementsin the industry. A microwave link may be builtby one company, operated by another, to carryservices for a third. The locus of responsibility forsystem integrity and performance is sometimeshard to decipher in these cases.

The existence of a scientifically-determinedbasis, developed by a government agency, forcalculating recommended clearance zonesbetween radio links and wind turbines is avaluable asset for both industries. Industryconfidence in its accuracy and dependability willgrow as experience of co-existence of radio linksand wind farms develops. In the meantime,experience has shown that the willingness ofwind power developers to address some of thetelecommunications industry uncertainties canease the process of project approval. Re-surveysto more accurate standards of the transmitterand receiver locations on a microwave link havethe potential to reduce the required clearancezone around a link by an order of magnitude.

Scanning telemetry systemsThe precise required clearances around the linkpath for scanning telemetry systems (usedprimarily by the water and power industries) areunclear and are at the discretion of thetelemetry system operator. Some operators havetaken Ofcom's consultation trigger distance (1kmfrom a scanning telemetry station) as a requiredavoidance zone.

The consultation process for scanning telemetrysystems is also complex. Ofcom has no remit forand no data on these systems and responsibilityfor their integrity and performance is held byagency bodies under contract to the systemowners. However, these agencies may not holdcomplete information on the locations oftelemetry links and stations. This is compoundedby industry reluctance to release suchinformation, apparently on security grounds.

Wind industry experience has shown thatwillingness to respect confidentiality, combinedwith the sharing of examples of successful co-existence of wind farms and a variety oftelecommunications systems, can ease theprocess of consultation with telemetry systemoperators.




1 Spaven Consulting (2001). Wind Turbines and Radar: Operational Experience and Mitigation Measures. Available at:http://www.bwea.com/aviation/Wind-Turbines-and-Radar-Operational-Experience-and-Mitigation-Measures.pdf

2 Bacon, D.F. (2002), A proposed method for establishing an exclusion zone around a terrestrial fixed radio link outside ofwhich a wind turbine will cause negligible degradation of the radio link performance, Version 1.1, RadiocommunicationsAgency. Available at:http://www.ofcom.org.uk/radiocomms/ifi/licensing/classes/fixed/Windfarms/windfarmdavidbacon.pdf

3 RA/BBC/ITC (1992). Environmental Impact: Effect of wind farms on UHF television reception. Engineering InformationBulletin, June 1992.

FURTHER INFORMATION

In addition to the references cited in the text above, further information is also available from thesources below:

1. A. Knill (2002). Potential Effects of Wind Turbines on Navigational Systems. Available at:http://www.bwea.com/aviation/Potential-Effects-of-Wind-Turbines-on-Navigational-Systems.pdf

2. Summers, E. (2001). The Operational Effects of Wind Farm Developments on ATC Procedures forGlasgow Prestwick International Airport’. Glasgow Prestwick International Airport. Available at:http://www.bwea.com/aviation/Operational-Effects-of-Wind-Farm-Developments-on-ATC-Procedures-for-Glasgow-Prestwick-International-Airport.pdf

3. Summers, E. (2002). Wind Turbines and Aviation Interests - European Experience and Practice.ETSU W/14/00624/REP, DTI PUB URN No. 03/515. Available at:http://www.bwea.com/aviation/European-Experience-and-Practice.pdf

4. DTI/MOD/CAA/BWEA (2002). Wind Energy and Aviation Interests: Interim Guidelines. Availableat: http://www.dti.gov.uk/energy/renewables/publications/pdfs/windwnergyaviation.pdf

5. QinetiQ (2003). Wind Farms Impact On Radar Aviation Interests - Final Report. FESW/14/00614/00/REP, DTI PUB URN 03/1294. Available at:http://www.dti.gov.uk/energy/renewables/publications/W1400614.shtml

6. Alenia Marconi Systems Ltd (2003). Feasibility Of Mitigating The Effects Of Windfarms OnPrimary Radar. ETSU W/14/00623/REP, DTI PUB URN No. 03/976. Available at:http://www.dti.gov.uk/energy/renewables/publications/w00623.shtml


How noise is measuredSound is always associated with small scalechange in pressure, which produces sensations(i.e. is ‘heard’) at the human ear. Because of thewide range of sound pressures to which the earresponds, sound pressure is an inconvenientquantity to use in graphs and tables and sonoise is measured on a logarithmic scale indecibels (dB). The decibel is a measure of thesound pressure level, i.e. the magnitude of thepressure variations in the air.

A change in sound level of 1 dB cannot beperceived, except under laboratory conditions.Doubling the actual energy of a sound source ordoubling the number of identical sound sourcescorresponds to a 3 dB increase. A 3 dB changein sound level is considered a barely discernibledifference, outside the laboratory.

The noise that a machine such as a wind turbinecreates is normally expressed in terms of itssound power level. Although this is described indB(A), it is not a measurement of the noiselevel but of the power emitted by the machine,which then creates the sound pressure levelwhich can be heard and measured using asound meter.

Sources of wind turbine noiseStanding next to a wind turbine, it is usuallypossible to hear a noise often described as awhoosh or a swish as the blades rotate. Thewhirr of the gearbox and generator may also beaudible, depending on the type of turbine.

There are plenty of detailed reviews of thesources and noise generation processes of windfarm noise1, but in general, the sources of noiseemitted from operating wind turbines can bedivided into two categories, mechanical andaerodynamic.

Mechanical noise Mechanical noise is transmitted along thestructure of the turbine and is radiated from itssurface. The hub, rotor, and tower can all act asloudspeakers, transmitting the mechanical noiseand radiating it. Because it is associated withturning machinery, this noise can be heard at adistinct constant frequency, described as ‘tonal’.

Aerodynamic noiseThe biggest contributor to the total sound powerfrom a turbine is the aerodynamic noise whichis produced by the flow of air over the blades.The proportion of noise from each source istypical of modern wind turbines. A large numberof complex flow phenomena occur which cangenerate aerodynamic noise. There is muchongoing research into these phenomena.

Broadband noise is often caused by theinteraction of wind turbine blades withatmospheric turbulence, and is also described asthe characteristic ‘swishing’ or ‘whooshing’sound of wind turbines. Airfoil noise alsoincludes the noise generated by the air flowright along the surface of the airfoil. This type ofnoise is typically of a broadband nature, buttonal components may occur due to blunttrailing edges, or flow over slits and holes.

Low frequency noiseLow frequency noise, with frequencies in therange of 20-100 Hz, is mostly associated with‘downwind turbines’, with the rotor on thedownwind side of the tower. It is caused whenthe turbine blade encounters localised flowdeficiencies due to the flow around a tower.When a rotating blade encounters this, pulses oflow frequency noise are generated. Turbinesthat have their rotors upstream of the tower,except in very rare circumstances, do notgenerate such pulses since there is nothingblocking the flow upwind of the rotor. When itdoes occur, because of the low rotational rates

Annex DNoise


of modern turbine blades, the peak acousticenergy radiated by large wind turbines is in theinfrasonic range with a peak in the 8-12 Hzrange.

Infrasound is generally defined as low frequencynoise below the normal range of humanhearing. A recent review of wind turbine dataindicates that wind turbines with an upwindmotor generate very faint infrasound with alevel far below the threshold of perception2. Thispaper concludes that infrasound from upwindturbines can be ignored in the evaluation of theenvironmental effects of wind turbines.

The levels of infrasound radiated by the largestwind turbines are very low in comparison toother sources of acoustic energy in thisfrequency range such as sonic booms, shockwaves from explosions and large industrialsources. The danger of hearing damage fromwind turbine low-frequency emissions is remoteto non-existent. It has also been stated that thepeak infrasound level from a large wind turbinesystem is well below the discomfort levelassociated with low frequency noise3.

Typically, except very near the source, peopleout of doors cannot detect the presence of low-frequency noise from a wind turbine.

Impulsive/beating noiseThe audibility of these periodic audible swisheshave recently been linked to stable atmosphericconditions (so are less likely to be heard duringthe day, during heavy cloud, during strong wind,and in a flat landscape) and also to thepossibility of the heightening of these effectsdue to the partial synchronising of these pulsesfrom several turbines in a wind farm4. Turbinesthat have their rotors upstream of the towersuch as those in the UK, except in very rarecircumstances, do not generate impulses.

Noise and wind turbine operationWind turbines do not operate below the windspeed referred to as the cut-in speed, usuallyaround 3-4 metres per second. Wind data fromtypical sites in the UK suggests that wind speedsare usually below this for about 20-30% of thetime, during which noise is not generated.

Large, variable speed wind turbines often rotateat slower speeds in low winds, increasing inhigher winds until the limiting rotor speed isreached. The newest turbine designs includesystems to change the rotor speed as the windchanges, and with variable speed control it ispossible to programme the turbine sound levelsbefore installation, so the operation of theturbine is micro-managed for the specificcharacteristics of the chosen location.

Reduction of noise with distance In order to predict the sound pressure level at adistance from a known sound power level, themethod of sound wave propagation must beknown. In general, as noise propagates withoutobstruction from a point source, the soundpressure level decreases. The initial energy inthe noise is distributed over a larger and largerarea as the distance from the source increases.

Generally, sound attenuates at 6dB per doublingof distance. In all cases, at twice the distance,the area through which the sound energy passesincreases by a factor of four and the pressurefluctuations reduce by a factor of two, resultingin a 6dB reduction.

For sound propagation in the real world, one ofthe key points with these additional attenuationfactors is that they are generally dependant onthe frequency of the sound5. For example, lowfrequency components of sound will beabsorbed less readily by the atmosphere and areless readily blocked by barriers6.

Annex D: Noise


As a typical example of sound propagation,depending of the size of the turbine, at onerotor diameter distance from the base of a windturbine emitting 100 dB(A) the sound level isusually about 55-60 dB(A). At four rotordiameters away it will be 44 dB(A),corresponding to a quiet living room in a house,and at six rotor diameters away it will beapproximately 40 dB(A).

Noise reduction methodsTurbines can be designed or retrofitted tominimise mechanical noise. Examples includethe helical gearing of gearwheels to reduce thenoise level of the gearbox, and mounting thegenerator, gearing and other components insuch a way that vibrations are damped and arenot transferred.

Recent improvements in mechanical design oflarge wind turbines have also resulted insignificantly reduced mechanical noise in theform of pure tones. Thus the noise emissionfrom modern wind turbines is dominated bybroadband aerodynamic noise7. Efforts to reduceaerodynamic noise have included the use oflower tip speed ratios, lower blade angles ofattack, upwind turbine designs, variable speedoperation and most recently, the use of speciallymodified blade trailing edges1. Advanced bladeproduction techniques have included innovationssuch as reducing sensitivity to roughness on theleading edge of the blade, and maintaining agood geometrical relationship between oneairfoil thickness and the next.

Defining an acceptable level ofnoiseAs stated before, the response of a person tonoise is very subjective. Because of the widevariation in the levels of individual tolerance fornoise, there is no perfect way to measure thesubjective effects of noise or of thecorresponding reactions or annoyance and

dissatisfaction. For this reason, targets andcriteria are usually set to provid broad protectionfor a community and the amenity of an area.

Standard UK practice is to define a frameworkwhich can be used to measure and rate thenoise from wind turbines and to provideindicative noise levels thought to offer areasonable degree of protection to wind farmneighbours and to encourage best practice inturbine design and wind farm siting and layout.

The potential noise impact is usually assessed bypredicting the noise which will be producedwhen the wind is blowing from the turbinestowards the houses. This is then compared tothe background noise which already exists inthe area, without the wind farm operating.

The World Health Organisation’s (WHO)publication ‘Guidelines for Community Noise’states that general daytime outdoor noise levelsof less than 55 dB LAeq are desirable to preventany serious community annoyance and thatinternal levels of 30 dB LAeq are desirable toprevent sleep disturbance at night8.

National planning policy (PPG 24 `Planning andNoise’) and accepted methods for ratinglikelihood of complaint (BS 4142:1997) are alltaken into account in a report produced by theWind Turbine Noise Working Group9, establishedby the DTI, which recommends ways to assessand rate wind turbine noise.

This states that turbine noise level should bekept to within 5 dB(A) of the average existingevening or night-time background noise level.This is in line with standard practice forassessment of most sources of noise except fortransportation and some mineral extraction andconstruction sites when higher levels are usuallypermitted. A fixed lower value for these limits ofbetween 35 and 40 dB(A) is also specified when

Annex D: Noise


background noise is very low, namely less than30 dB(A).

Defining background noiseBecause of the importance of the background indetermining the acceptability of the noise levelsit is crucial to measure the background ambientnoise levels for all the wind conditions in whichthe wind turbine will be operating.

Assessment of background noise levels atpotentially sensitive locations requires themeasurement of noise levels for a range of windspeeds measured at the proposed site of thewind turbines. This compensates for anydifference of wind speeds between the windturbine site and the sensitive site which may besheltered from the wind. Assessment ofbackground noise levels is especially importantat the cut-in wind speed of the turbines, sincethe background noise levels are likely to be lowin these circumstances.

Defining a source level for wind turbinesMuch of the interest in wind turbine noise isfocused on the noise anticipated from proposedwind turbine installations, based on theinformation which is provided by manufacturers.Wind turbines are too big to test for noise levelsin a special acoustic test chamber. It is thereforenecessary to deduce the noise source power byindirect means. Measurement of the sourcesound power level is made according toprocedures set out in several standards designedto ensure consistent and comparablemeasurements. These include the IEC 61400-11standard which is used in Europe. In order tocalculate noise levels heard at differentdistances, the reference sound levels need to bedetermined. This is the acoustic power beingradiated, and is not the actual sound levelheard.

Predicting levels at housesAs described previously, sound propagation is afunction of many factors. There are acceptedpractices for modelling sound propagation whichtake all these factors into account and there is avariety of propagation models in current usage.

The least complex propagation models, whichsimply address sound wave dispersion and makeconservative assumptions about other factors,are primarily used by wind farm developers tohelp optimise their proposed layouts. In thisway, the proposed location of wind turbineswhich are contributing heavily to combinednoise levels at house can be moved. In general,the models which are used assume downwindpropagation, i.e. that there is a slight windblowing from the turbines to the modelledhouses.

Prediction methods are constantly revised andreviewed in light of research and experience,looking at issues such as the fact that the sourceof the noise generation is increasing as turbinesincrease in height, with consequent impacts onpropagation and wind effects.

Compare predicted levels with criteria In the UK, the current practice controlling windfarm noise is by the application of noise limitsat the nearest noise sensitive properties. Theemphasis is on developers to demonstratecompliance with these limits prior to theconstruction of the wind farms. Thus in the UK,planning assessments normally provide anindication of the ability of candidate turbines tomeet noise limits since it is not always possibleto quote the basic sound power level of newand proposed wind turbines to a relevantdegree of accuracy. In this way the onus is onthe developer to comply with the noise limitsimposed by the planning authority for apermitted wind farm site.

Annex D: Noise


1 Wagner, S., Bareib, R. and Guidati, G. (1996). Wind Turbine Noise. Springer, Berlin.

2 Jakobsen, J. (2004). Infrasound Emission from Wind turbines. Proceedings from Low Frequency 2004, 11th Internationalmeeting on low frequency noise and vibration and its control. Information available at: http://www.multi-science.co.uk/lf2004-pro.htm

3 Shpilrain, E. (2001). Environmental Aspects of RES Utilization For Distributed Power. Proceedings from Distributed PowerProblems, Opportunities And Challenges. Information available at: http://www.worldenergy.org/wec-geis/news_events/member_news/miec/aspects.asp

4 Van de Berg, G. (2004). Do wind turbines produce significant low frequency sound levels. Proceedings from LowFrequency 2004, 11th International meeting on low frequency noise and vibration and its control. Information availableat: http://www.multi-science.co.uk/lf2004-pro.htm

5 Beranek, L. and Ver, I. (1992). Noise and Vibration Control Engineering: Principles and Applications. Wiley, New York.

6 ISO (1996). 9613-2: Acoustics – attenuation of sound during propagation outdoors. International Organization forStandardization, Geneva.

7 Fégeant, O. (1999). On the Masking of Wind Turbine Noise by Ambient Noise. Proceedings from European Wind EnergyConference, Nice, France, March 1-5, 1999.

8 WHO (2000). Guidelines for Community Noise. World Health Organisation, Geneva. Available at:http://www.who.int/docstore/peh/noise/guidelines2.html

9 ETSU (1996). ETSU R97: The Assessment & Rating of Noise from Wind Farms. Available at:http://www.dti.gov.uk/energy/renewables/publications/noiseassessment.shtml

FURTHER INFORMATION

In addition to the references cited in the text above, further information is also available from thesources below:

1. Hubbard, H. and Shepherd, K. (1990). Wind Turbine Acoustics. NASA Technical Paper 3057DOE/NASA/20320-77.

2. IEC (International Electrotechnical Commission). IEC 61400-11: Wind turbine generator systems– Part 11: Acoustic noise measurement techniques. Document No. 88/141/CDV.

3. Leventhall (2003). A review of published research on low frequency noise and its effects. Areport for Defra. Available at:http://www.defra.gov.uk/environment/noise/lowfrequency/pdf/lowfreqnoise.pdf

4. National Wind Coordinating Committee(1998). Permitting of Wind Energy Facilities: AHandbook. RESOLVE, Washington D. C.

5. Rogers and Manwell (2004). Wind Turbine Noise Issues – White Paper. Renewable EnergyResearch Laboratory, University of Massachusetts.

Annex D: Noise


Annex EBirds and Wildlife

HabitatsThe majority of onshore wind farms are based inupland areas, with upland moorland being mostcommon vegetation type. There has recentlybeen a move by renewable energy developersto try to site wind farms largely withincommercial forestry plantations in upland areas.From an ecological perspective this is a positiveuse of land which has already been changedand has less ecological and nature conservationvalue. Tree cutting around turbines and accesstracks and the overall use of the land for thispurpose will not usually result in significanthabitat change. It is often possible to encouragegreater habitat diversity such as forest edgeenhancement and habitat regeneration in thesurrounding area by removing larger areas ofafforestation and enhancing surroundinghabitats such as drained bog, as part of suchdevelopment.

Wind farms planned for and sited on nativeupland habitats do result in habitat change andloss. Whether this is significant in natureconservation terms really depends on thehabitats involved and their relative importance.It is difficult to generalise with such habitat loss,since it depends on the particular location,habitat types and the past management.Overall, a wind farm development that largelyresulted in the loss of species-poor rush pasturewould have less ecological impact than onewhich resulted in the loss (direct and indirect) ofpatterned blanket bog.i

Habitat loss comes from the turbine bases, plusthe necessary access tracks and borrowpitsii/quarries in wind farm development. The

latter is often much more in total area than theamount of land required for turbines. Accesstracks to the site and the turbine bases needsubstantial volumes of stone which tends to besourced locally, resulting in further habitat lossthrough opening up areas for stone quarries.Connection of the turbines to a substation andthe National Grid can also lead to further habitatloss. The precise impact on habitat of the gridconnection depends on the terrain and themethod of connection, e.g. underground cable,wooden pole line or pylon line. Generally, aboveground connection causes less habitat damagethan underground connection, unlessunderground connections can be routed underexisting tracks and roads or in low valuehabitats. Wind farms are often regarded astemporary structures. In some habitats this istrue as they can and will recover fairly rapidlyon decommissioning. Not all habitat loss isnecessarily permanent and with the correctlocation and construction methods even theimpacts of access tracks can be minimised byallowing for removal when the wind farm isdecommissioned. This can achieve longer-termhabitat recovery. With careful constructionhabitats can be created or returned aboveturbine bases and on construction compoundsduring the life of the wind farm, and themitigation provided for habitat loss can providebenefits for the future management ofsurrounding habitats. This all depends onlocation and careful ‘micro-siting’ of theelements involved because even the provisionof various compensation habitats will not alwaysreplace what is lost. Sensitive habitats that takea long-time to develop such as pristine bogs andancient semi-natural woodland are hard toreplicate. There are also other issues related to

i Active blanket bog (i.e. blanket bog which still has the peat building species present in sufficient quantity to assume thatpeat is still being created) is a habitat which is important at a European level and requires formal protection (priorityEuropean habitat type).

ii A borrow pit is a traditional name for a small quarry, often in the side of a small hill next to a track that stone is removedfrom to allow the track to be constructed.


impacts on habitats which need carefulconsideration during wind farm planning. Two ofthe most important issues for upland habitatsare the potential effects on the water regime ofpeat bodies underlying peatland habitats andthe potential for instability in peat bodies toresult in the downslope mass movement ofpeat, often called a peat slide. The key toavoiding deleterious effects on peat bodies isconsideration of the wind farm location, schemedesign and environmentally sensitiveconstruction methods.

Indirect habitat loss through pollution andconstruction disturbance can also occur as aresult of careless construction practice. This canhappen with wind farm construction as it canwith most large-scale construction projects. It istotally preventable with the correct planningcontrols and environmental supervision. Duringwind farm planning and construction theprotection of watercourses is extremelyimportant since pollution of upland streamstravels rapidly downstream and affects habitatquality outside the wind farm. The prevention ofsuch pollution is also particularly important forprotected species which may be present inwatercourses, some of which – Atlantic salmon,for example – are particularly sensitive topollution.

Birds

The British Isles as an internationallyimportant refuge for birdsThe islands which make up Britain are stronglyinfluenced by the sea. There is over 11,000kmof coastline and nowhere is more than 115kmfrom the seaside. Some 120 estuaries drain intothe shallow waters of the seas around Britain.The warming effect of the North Atlantic Driftensures that, for the most part, these estuariesdo not freeze in winter.

Britain has an international responsibility for anumber of important bird populations associatedwith our marine and estuarine habitats. Vastcolonies of seabirds breed around our coast line,for example 330,000 pairs of Manx Shearwatersbreed in Britain and Ireland representing 90% ofthe world population.1 Its estuaries support hugenumbers of wildfowl and wading birds thateither migrate along the east Atlantic flyway orstay throughout their non-breeding season. TheBritish and Irish coastlines are home to some 3million wading birds in the winter months.2

Important numbers of wildfowl include 84% ofthe world population of Greenland White-fronted Geese that winter in the British Isles andall of the 14,000 Barnacle Geese that breed onthe high Arctic island of Spitsbergen and spendtheir winter in the Solway Firth1.

The peat and heather moors of Britain are hometo internationally important numbers ofbreeding Dunlin, Golden Plover and Greenshank1

and the world population of Red Grouse3. Partsof the Scottish Western Isles are the last refugein Britain of the rare and globally threatenedCorncrake1. The UK’s only endemic species, theScottish Crossbill, is found in a few remnantpockets of the ancient Caledonian pine forest inScotland4.

Climate change and the threat to birdlifeGlobal warming is already affecting birds inBritain, for example Swallows are now migratingto Britain on average one week earlier thanthey did 30 years ago5. Other species arebreeding significantly earlier and it is expectedthat many will get out of step with the foodresources needed to feed their young6.

The current accelerated global climate change isthe greatest long-term threat to wildlifeworldwide7. The rapid and significanttemperature changes that are occurring todaywill directly affect the wildlife habitats that are

Annex E: Birds and wildlife


being conserved, by changing the conditions forthe plants that they support. This will greatlymodify these habitats and the animalcommunities that live within them.

Prior to human impacts on the world, mostwildlife was able to accommodate changes inglobal temperature because the changes wereslow and the wildlife able to migrate to aclimate that best suited them. Today suchmigrations are impossible. In Britain 80% of thecountryside is put to agricultural use added towhich there are the built environments of cities,industrial sites and road networks all of whichprovide a barrier to wildlife migration8. ProfessorSir John Lawton, Chief Executive of the NaturalEnvironment Research Council, described thiscritical problem of wildlife fragmentation as‘islandisation’. Islandisation within the currentcontext of rapid global warming will inevitablylead to a mass extinction of wildlife7.

As the seas warm, water expansion and land icemelts will mean the continued inexorable rise insea levels. This is causing ‘coastal squeeze’where the inter-tidal habitats that supportinternationally important populations ofwildfowl and wading birds are being lostbetween the rising low water mark and coastalsea defences9. It has been calculated that by2080, if global warming continues at its presentrate, the sea level around Britain will have risenbetween 26 and 86cm10. The impact on birdsthat use inter-tidal habitats is self evident. Thiswould, for example, result in an 11% loss of theEast Anglian population of breeding RingedPlover11.

The salt marshes, which form between thestrand lines of the mean and spring tides, areparticularly vulnerable to coastal squeeze andare home to 86% of the breeding Redshank inEngland9. Between 1986 and 1993, 44% of the

Essex salt marshes had already been lost in thisway9.

The high mountain tops in Scotland areinhabited by a number of rare breeding birdsthat are restricted to these zones. Among thesespecialist birds are Ptarmigan, Dotterel andSnow Bunting. The habitats that support themare temperature sensitive and an annualaverage rise of just 3oC would destroy themcompletely12. Global warming, if left unabated,will render all three species extinct as Britishbreeding birds by the end of this century.

The impact of wind farms on birdsWind farms cause problems for birds in six ways:

• Birds may have fatal collisions with turbines.

• The land that the development takes up byway of roads, turbine bases and the likeremoves habitat for birds.

• Some birds simply do not like living within ornext to wind farms and are thereforedisplaced.

• During the construction and decommissioningof wind farms birds may suffer considerabledisturbance.

• Wind farms may act as barriers to birdmovements where they are unwilling to flyaround or over them. Short increases in flightaround a wind farm may be inconsequentialbut the cumulative effect on energyexpenditure could be a cause for concern.

• Any of the above in themselves may betolerable to birds but in combination throughdeaths and/or displacement and/ordisturbance may bring populations underthreat.

No one likes to see bird populations harmed butmore often than not the impacts from wind farmsare actually negligible and in the sense ofcombating global warming these problems can



represent an acceptable trade-off. Clearly thereare some areas in which, if wind farms wereconstructed, such as in the middle of a seabirdcolony or the breeding territory of an endangeredspecies, then unacceptable impacts on birdswould be wrought by wind farm developments.

In order to adequately assess the impacts onbirds of proposed wind farms Scottish NationalHeritage (SNH) has developed a robust andobjective guidance system for the assessment ofimpacts on birds by proposed wind farms – thisguidance is currently being revised. In somecases the predicted impacts on birds have beenthe primary reason for a site being rejectedduring the planning process13.

The purpose of this approach is to allowdevelopers and conservation organisations to beable to work together to:

• Ensure that a wind farm development doesnot occur in an inappropriate place whereimportant bird populations will be adverselyaffected.

• Ensure that insignificant bird issues do notinhibit wind farm developments.

• Identify where enhancements can beachieved for birds through appropriatemitigation measures13.

• Ensure that adequate baseline information isobtained to minimise uncertainties and enableplanning applications to be determined on aninformed basis.

The SNH system provides a phased approach tothe assessment of risk to birds. The first phaseinvolves an initial desk-based study and on-siteassessment which provides the baseline birddata. Occasionally the baseline information issufficient to demonstrate that there are no

significant negative impacts on birds and nofurther work is necessary.

Where species of conservation concern areidentified as being potentially at risk aprogramme of bird monitoring and survey workappropriate to the bird interest of the site isdeveloped, forming the second phase of thesystem. Integral to this is an assessment of therisk of collision of all species of conservationconcern with the wind turbines, an assessmentof the sensitivity of the site in the context ofnature conservation and its magnitude of impacton significant bird populations.

Where an assessment predicts that there is arisk of significant adverse effects then the thirdphase of the impact assessment exploresmeasures to mitigate the problem such as therelocation of turbines or the options for habitatimprovement or creation outside thedevelopment envelope. The relevantornithological chapter in the EnvironmentalStatements that accompany all planningapplications for wind farms are drawn up fromthe results of this programme of systematicstudy. The Council of Europe through itsconvention on the conservation of Europeanwildlife, the Bern Convention, has also publishedguidance on environmental assessment criteriaand site selection issues relating to wind farms14.

Wind farms and bird behaviourThe overriding reason why birds are at risk fromwind farms is that they do not, or cannot, alwaysalter their behaviour to accommodate them. Forexample soaring species, which need risingwinds to get off the ground, may be particularlyaffected by turbines situated on ridges used bythese birds for lift, close to their roosts15/iii. It isnot known whether habituation occurs over time.


iii The Griffon Vulture is one example, although this species is not found in the UK.


Bird behaviour in relation to wind farms can beconveniently divided into two main areas:

(1) the ways in which flying birds negotiatewind farms and

(2) their tolerance to wind farm structures whilstfeeding, roosting or breeding.

Flying birdsBirds are at risk when attempting to passthrough the rotor plane. Natural behaviours andecological relationships of birds contribute totheir inherent sensitivity to wind turbines. Sinceeach bird species exhibits unique suites ofbehaviours, geographical distributions, andecological relationships, each also possessesunique sensitivities to wind farms. Thissensitivity is estimated by measuring andcomparing behaviours that could causeindividual species to collide with wind turbinesshould these behaviours continue unalteredafter wind turbines become operational.

Birds try to pass through the rotor plane becausethey simply cannot see rotating turbine bladesor if they see them they either do not recognisethem as hazards or are unable to avoid them. Inthe case of birds of prey it may be because theirvision is fixed on the prey that they are pursuingbeyond the blades16. Raptors identify a preyitem and continuously observe it until theycapture it. If the raptor’s target is located behindthe rotating blades of a turbine, then the raptormay not see the blades or may see them whenit is too late to avoid them. The relative effectsof peripheral vision versus fixed focus on preyitems remains unknown, as does the degree towhich these two factors might interact17.However, it is important to note that birds otherthan birds of prey also fatally collide with windturbines.

The vast majority of bird flights through windfarms result in the individuals successfully

negotiating a route through the wind farmstructures, presumably with little difficulty. Instudies, collision rates were typically in range of1 in 1,000-10,000 bird flights through the windfarm13. In some cases collision rates areconsiderably lower, such as at the offshore windfarm at Utgrunden, where over 500,000 eiderflights through the wind farm study area havebeen observed without a single collision beingrecorded18. Studies using radar tracking havehelped to provide further information on thegeneral ability of birds to avoid collisions.Studies in the Netherlands, for example, showedthat nocturnally flying Pochard and Tufted Duckflew regularly through a wind farm undermoonlit conditions but flew around the turbinesat greater distance from them when it was darkor foggy19.

Collision rates often need to be interpreted withcaution as they can be quoted as averageswithout an indication of the range of valuesfrom which the average has been calculated.There can be substantial variation betweendifferent turbines, crucially depending on theirlocation with respect to the main bird flightroutes. Nonetheless, there is general consensusthat collisions tend to be low frequency events,although the relative impact may be higher forcertain species (eg. rare, long-lived birds) thanfor others.

Bird tolerance to wind farmsIt has been shown through various studies thatsome birds will tolerate wind farmdevelopments and behave very much as beforethe wind farm was constructed. For example:

• In Orkney there were no differences in thenumbers of breeding pairs of ducks, waders,Arctic Skuas, gulls and small birds as a resultof the wind farm being developed19.

• At a site close to the Wadden Sea in theNetherlands there were no effects on



breeding Oystercatchers, Lapwings, Black-tailed Godwits or Redshank from the windfarm20.

• In a study at Ovenden Moor wind farm in theYorkshire Pennines the number of breedingGolden Plover actually increased over a fiveyear period within the wind farm area incontrast to a control site where numbersremained constant.

• At Bryn Titli in mid-Wales, a study showedthat Ravens successfully nested within 60m ofa wind turbine21.

It should be noted that wind farm developmentsand turbine size so far have been relativelysmall, and that much larger developments arelikely to come forward as the industry matures.This may make it difficult to draw conclusionsfrom these studies for very large projects andmore research may be required.

The major potential impact of wind farms onbirds is displacement from the developmentarea caused by the removal of habitat, cautionshown toward physical structures or the effectsof disturbance through human activity or rotornoise or motion. In Denmark, the feedingdistribution of wintering Pink-Footed Geesearound wind farms was studied in detail22. Birdskept about 100m away from single or rows ofturbines, and 200m from clusters of turbines.Other structures in the local landscape such ashedgerows, roads and buildings, had similareffects.

Variable results have been found for otherspecies of goose. On spring staging grounds inGotland, Barnacle Geese fed as close as 25m towind turbines23. A study of the same populationon the wintering grounds in Germany, however,found almost no geese feeding within 350m ofwind turbines and partial displacement up to600m. The different distribution of the food

resources at each site may well be anexplanation for this variation. That is to say thatif birds are hungry and the distribution ofavailable food reserves is in close proximity towind turbines then birds are less likely to bedisplaced than if food is more abundant andwidespread. It seems that displacement is highlyvariable and is species and site specific.

There remains a dearth of studies into thedisplacement effects on birds of the onshorewind farms in upland Britain and the scientificknowledge is therefore scant. There is generallymore evidence of displacement of birds aroundwind farms occurring in coastal habitats. Most ofthe examples of such disturbance relate towaterfowl, over distances of up to 800m inwintering birds and 300m in the breedingseason.

Mitigation and compensation measuresThere are a number of ways in which theimpacts of wind farm development on birds canbe mitigated. There are a range of optionswhich are not always appropriate to all sites butplanners are able to review the detail withwhich developers have considered themitigation measures for birds within theirproposals from knowledge of these options.

Constraints planningPhase 2 of bird monitoring programmes forproposed wind farm developments takes aminimum of a year and reviews bird activitiesthroughout the site across all seasons to takeinto account breeding, migrating and winteringbirds. Throughout there is an iterative processbetween the ornithologists undertaking thesurveys and the developers. Important elementsof those iterations are to review the findings ofthe studies with the wind farm plans. Carefulconsideration can then be given to such issuesas turbine layout before any planningapplication is lodged.



In many cases it has been discovered that thereare preferred bird flight paths through aproposed site. Examples of these includebreeding birds moving between the nest andfeeding sites,iv wintering wildfowl that aremoving between a roost and feeding locationsv

and ridges favoured by soaring or hunting birdsof prey.vi In other cases important breeding sitesthat were not previously known about havebeen found.vii Importantly, these findings byornithologists have been able to significantlyinfluence the wind farm plans and in someinstances turbine locations have been moved orturbines have been completely removed fromthe overall scheme to avoid these sensitiveareas.

Construction mitigationEnvironmental responsibilities should be takenvery seriously during the construction of windfarms. It is common for developers to employ asite ecologist and on sites where there are birdsensitivities a site ornithologist may beemployed to support the site ecologist duringthe construction process. Such is the case, forexample, at Farr and Hadyard wind farmdevelopments in Scotland. This would representgood practice and should be encouraged.

The impacts on birds during the constructionphase are most acute during the breedingseason and come from the potential disturbanceto, and destruction of, nests. In the first instance,development should be timed to avoid thebreading season where possible. Indevelopments that have to go ahead within a

breeding season, ground nesting birds are oftendissuaded from attempting to breed byremoving the surface vegetation within the‘footprint’24. However, this may be particularlydisruptive to certain species, such as breedingwaders, which are long-lived and often highlysite-faithful. When deemed necessary otherphysical exclusion techniques are also employedto prevent nest building and breeding attemptsand include the use of tapes and flags. Duringand after construction the number of fences andguy wires should be kept to a minimum,particularly where species of grouse are knownto be present as it has been shown that theseare one of the major causes of mortality in suchbirds which fly low, fast and straight withlimited manoeuvrability.25

Habitat improvementsWhile constraints planning can help to mitigatethe problems for birds from wind farms,developments may also offer opportunities tocompensate or even improve habitats throughhabitat improvement work outside thedevelopment areas. Developers and plannershave a responsibility to look at the potential forsuch options within all wind farm proposals.

The Beinn an Turic wind farm in Argyll andBute – extensive mitigation plans were put inplace to enhance 14,000Ha of upland moorlandfor breeding birds. Within the plans 500Ha ofbiologically unproductive Sitka Spruce plantationwere felled. The general habitat improvementsby far outweighed any habitat lost due to thedevelopment itself. It is possible to manipulate


iv A site in Caithness, Scotland, where it was discovered that Red-Throated Divers were commuting from their breedinglochans to feed at sea through a proposed wind farm site.

v A site in Caithness, Scotland, where it was discovered that a flock of Whooper Swans were commuting through a proposedwind farm site from a roosting loch to day time feeding in fields.

vi A site in the Monadhliath Mountains, Scotland, where it was discovered that Red Kites were using a particular gully to getuplift.

vii A site on Lewis, Scotland, where it was discovered that Eagles were nesting.


habitats outside wind farms so that they holdgreater numbers of prey species than areactually within the wind farm itself. For examplesmall rodents can easily be encouraged, ordiscouraged, according to how grassland ismanaged. Through this manipulation certainbirds of prey can be passively relocated awayfrom the hazards of the wind farmdevelopment. This aspect of management wasthoroughly studied at Altamont Pass in theUnited States.26

Hadyard Hill in Lanarkshire – plans are beingput in place to enhance an area for BlackGrouse, a UK Biodiversity Action Plan species.10Ha of mixed deciduous open woodland arebeing planted in open grassy moorland, 15Ha ofmoorland are being converted into wet flushareas by the introduction of simple plastic pilingdams and 25Ha of mature commercial pineforest are being felled and restocked toincorporate open areas and edges planted withdeciduous trees. Such habitat improvements arebecoming more commonplace in wind farmdevelopments and make a positive contributionto the conservation of our wildlife as a whole.

Wind turbine location, placement,design and operationCareful consideration of the location and layoutof wind farms, the design of the associatedstructures, and regard for turbine operation willsignificantly mitigate the impacts of wind farmson birds.

Lessons learned from wind farmdevelopments and locationBoth in Europe and in the USA it has beengenerally acknowledged that certain wind farmdevelopments have been badly located andgiven rise to excessive bird mortality throughcollisions with wind turbines. At Altamont Passin California, USA, where the wind resource areahas some 1,110 turbines, a minimum of 382

birds were killed between March 1998 andDecember 2000 through collisions with turbines.A little over half of these casualties (53%) werebirds of prey and some species involved, such asGolden Eagles, were of high conservationconcern26. An even higher estimate of birddeaths was found at San Gorgonio wind resourcearea where it was calculated that 6,800 birdswere killed annually27. In Europe the Tarifa windfarm complex in the Campo de Gibraltar regionof Spain is notable in that it is positioned on animportant bird migration route. In addition todeaths of migrating birds there have been anumber of resident Griffon Vultures, a rarespecies in Europe, listed amongst thecasualties28.

Studies at Blyth29 and at Zeebrugge Harbours30

both found collision rates higher than one birdper turbine per year, well in excess of the otherstudies into collision rates at wind farmselsewhere. Data from Zeebrugge also showedvery high variability in the observed collisionrates for different turbine locations, rangingfrom 0 to 125 collisions per turbine per year. Atboth sites the wind farms had been positionedbetween onshore seabird colonies and theiroffshore feeding grounds.

These examples serve to remind planners andconsultees of their responsibility to thoroughlyreview the data contained within EnvironmentalStatements. Where they feel that there hasbeen insufficient data gathered upon which tomake sound judgements then there shouldalways be an insistence on further studies beingundertaken. The overwhelming imperative is toensure that wind farms that are likely to causeunacceptable impacts on bird populations arenot built in the future.

Turbine placementWind turbines placed near gullies and those atthe end of a string of turbines are more



dangerous to birds than others31. The inter-towerspacing and the height of turbine towers androtor diameters might interact to affect speciesvulnerability to turbine collisions. In addition,the percentage of time that wind turbinesoperate may also be an important factor in birdcollisions.

Painting rotor bladesThe as yet untested Hodos rotor blade paintingscheme32 may reduce the distance across whichmotion detection is experienced by birds of preywhich would allow them to detect themovement of turbine blades even though theyare extremely focused on their quarry.Essentially it involves one blade painted blackand two painted white, but achievedcumulatively by precise, evenly distributedpainting of black bands on all blades. Whilst ifgenerally applied to wind farms the effectwould be aesthetically unacceptable the system,if proved to be effective, could be usedjudiciously on specifically identified turbines.

PerchesResearch in the USA33 has shown that birds ofprey use turbines and other wind farmstructures as perches which are thought toincrease their risk of collisions. Indeed, whereturbines have been out of order significantincreases in collisions with adjacent operationalturbines were recorded.34 This was thought to beas a result of turbines that had been out ofcommission for some time being used asperches by birds of prey and flying birds takingaction to avoid the perched raptors flew,inadvertently, into the operational turbine nextdoor.

Benign towersIt has been suggested34 that the installation oflarge poles at the end of turbine lines might actas bird flight diverters. These poles could beplaced 5-10m apart and just beyond the rotor

plane of the wind turbine at the end of a stringand extend upward to near the high reach ofthe turbine’s blades. The idea is to encouragebirds to fly wider around the end of the turbinestring, thereby adding distance between thebird’s flight path and the operating windturbines. Poles serving as flight diverters shouldbe installed without guy wires, because guywires pose collision hazards to flying birds. Theyshould also be designed to prevent perching.Pointed tops might be one design to achievethis.

Turbine cessationWind turbines may be especially dangerous tobirds during unsettled weather conditions or inperiods of poor visibility, such as during fog,rain, darkness, dusk, or dawn35 and perhapsparticularly so during migration periods. Throughcareful study, however, the difficulties preciselyaffecting a particular population could beascertained and lead to the judicious shuttingdown of particularly problematic turbines withina wind farm at any particularly sensitive time ofyear.

It has been proposed that the precise periods ofgreatest danger might be ascertained byinstalling specially designed accelerometers.xiii

These devices, properly designed and installed,may be able to detect the precise time of eachbird collision. With sufficient data on times andconditions of bird collisions, patterns mightemerge that inform managers of higher risktimes of the day, or year, when temporaryshutdowns of certain wind turbines cansubstantially lessen bird mortality.

Relocation of selected wind turbinesIn all the studies that have investigated birdcasualties through turbine strikes, it has beenshown that certain wind turbines killdisproportionately more birds because of wherethose wind turbines are located. Once identified



the careful relocation of such `killer` turbineswould substantially reduce bird mortality.

The need for further researchTo date most of the detailed research about howbirds behave around wind farms and theimpacts they have upon them has beenconducted outside Britain. The scientificunderstanding of the impacts of wind farms onbirds is still in its infancy and there is muchwork still to be done. There is an urgent needfor a more standardised approach to themonitoring of adverse wildlife effects bothbefore and after construction. This could formpart of the consent conditions for the project,although it will be up to the UK Governmentand Devolved Administrations to decide whetherthis is desirable.

The most urgent need for further scientificunderstanding about birds and wind farms canbe summarised in these questions:

• How do the different species of conservationconcern behave around wind farms i.e. levelsof tolerance or displacement?

• How do different species behave in thevicinity of turbines (notably flight behaviour)and differentially avoid collisions and how isthis affected by different environmentalconditions such as weather or time of day?

• What are the long term impacts of buildingwind farms in areas important for the non-breeding elements of populations from wherebreeding stocks are replenished?

• How is the productivity of birds that remainwithin wind farms to breed affected? Forexample rates of post–fledging mortality maywell be unsustainably high as may be levelsof predation by predators brought in by theprospect of scavenging on collision casualties.

• How are birds affected by the disturbancecaused in the construction, operation

(maintenance and repair visits – probablymore appropriate to last bullet point) anddecommissioning phases of wind farms?

• Do wind farms act as barriers to birdmovements?

• What are the cumulative effects of wind farmson bird populations considering the increasingsize and height of developments?

• What are the short and long-termdisplacement impacts on birds fromoperational wind turbines?

• Effectiveness of mitigation measures

BatsBats are fully protected in UK law3. In broadterms wind farms/turbines have the potential toadversely affect bats in the following ways:

• Mortality from collision with the turbines andrelated structures

• Displacement due to the noise and presenceof the wind farm structures

• Direct habitat loss and reduction in habitatquality

• Indirectly through influences that windturbines and the associated infrastructure mayhave on bat prey and bat predators

CollisionExperience in the US and continental Europeshows that bats can collide with wind turbinesand there is some evidence that the levels ofmortality are increasing with the increase in sizeof the turbines. As with many man-madestructures such as electricity pylons and powerlines, meteorological masts, buildings etc, windturbines present a potential collision hazard.However, evidence from the US indicates thatwind farms cause bat mortality at a higher levelthan would be expected by their proportionalpresence in the environment.



The vast majority of bat fatalities are migratoryspecies (ca. 90%) during the migration period,rather than ‘local’ bats on nightly foraging trips.Fatalities are associated with known migrationroutes.

In the UK there are very few migratory speciesand no known ‘migration routes’ as are thoughtto be present in the US. Bats do migrate southin the winter in Europe but most seasonalmovements of bats in the UK are to and fromwinter hibernacula, which in some case caninvolve northerly movement in the autumn.These are not necessarily linked to seasonalclimatic trends.

There are a number of proposed hypotheses toexplain why migratory bat species are moresusceptible and to explain why wind turbinesappear to cause more collision fatalities thanmight be expected given their still relativescarcity in the landscape. One theory is that batsare attracted to wind turbines as potential stop-over day-time roost sites during nocturnalmigrations. Another theory is that migrating batsdo not echolocate (a type of natural active SONARthat bats use to detect insect prey and obstacles)and therefore rely on vision alone, increase theirrisk of colliding with objects.

In the UK there has been less consideration ofthe collision issue partly because of the fact thatwind farms have been active in the US andcontinental Europe for longer and partly becausethe evidence from the US indicates that mostspecies in the UK would not be at significant risk.However, there has not been a lot of detailedstudy to confirm that this is the case for the UK.

In summary, there is no evidence to suggestthat wind farms in the UK present a significantsource of mortality to bat populations, unlessthey are sited close to known concentrations ofbat activity (e.g. summer roosts, swarming sites,

hibernacula). However, there has not been a lotof attention paid to the issue in the UK andthere needs to be further study to confirm this.As a precautionary approach it is increasinglyimportant, as wind farms being to proliferateand increase in size, that all sites are assessedfor bat flight activity as part of the planningprocess so that potential impacts can be avoidedand/or reduced through design.

Habitat loss and degradation As with any development there is the potentialfor bat habitats to be affected either throughconstruction disturbance or through directhabitat losses from the wind farm structures (orassociated tree felling to increase wind yield).Typically, onshore wind farm sites are located inupland areas or in conifer plantations thatgenerally do not provide good foraging orroosting habitat for bats, although it is alwaysimportant to establish this for a particular sitethrough proper surveys and assessments. If batroost sites are found within proposed windfarms then the normal practice would be toavoid any disturbance to these areas and siteturbines, access tracks, borrow pits and anyoverhead power lines far enough away so thatbats are not affected by them.

Loss of foraging habitat (e.g. woodland andwoodland edge, ponds and streams, hedge rowsetc) associated with the construction of theturbine bases, access tracks, borrow pits, gridconnection etc can also affect bats. Althoughthere is no general legal protection of suchhabitats, in terms of their use by bats, the ‘bestpractice’ approach would be to avoid as muchloss of such habitat as possible and where someloss was unavoidable then to compensate forthis through habitat enhancement and creation.The design of such mitigation measures requirescareful consideration in the overall wind farmdesign so as to avoid creating attractive habitatfor bats near to any turbines.




There has been very little research work carriedout on the potential for the physical presence ofan operating wind farm to displace bats throughdisturbance or other means. There is no evidencethat wind turbines produce ultrasonic sounds thatcould either attract or repel bats. However, windfarms could affect aerial insect populations whichform the majority of bat prey through changes toinsect habitats or the attraction of insects to anyartificial lighting associated with the wind farm,thereby indirectly affects bats, either positivelyor negatively.

In summary, the favoured upland sites foronshore wind farms in the UK generally do nothost the best habitat types for bats. In mostsituations potential adverse effects on bathabitats can be avoided or successfullymitigated, provided that the appropriate surveywork is undertaken and that developersrecognise the need to consider the issue in theplanning and design of the wind farm scheme.Because of the strong legal protection affordedto bat roosts then these sites are normallyconsidered in the planning process. The effectsof large-scale wind farm development on batforaging habitat and habitats that act as links(flyways) or corridors between roost sites andforaging sites can also be important but havenot been extensively researched.

Other protected speciesThe potential for significant adverse effects onprotected speciesviii like otter, badger, wild cat,pine marten, red squirrel etc. relates to theplanning and micro-siting of turbines and accesstracks. With adequate environmentalassessment and design, longer-term disturbanceto protected species can be avoided, although

this is likely to be short-term in nature as theyare expected to habituateix. If the ‘homes’xi ofprotected species are not directlydisturbed/destroyed during construction workthen it is widely accepted in most cases thatmitigation can be put in place to prevent anyother potentially significant adverse effects suchas fragmentation. Mammals (except bats) arenot likely to come into direct conflict with theturbines. Habitat loss for wind farmdevelopment is not likely to be significant forprotected species if adequate environmentalsurvey work is undertaken in planning the site.Often particular localised issues such as theavoidance of a regularly used mammal path canbe fully mitigated by careful micro-siting of anaccess road or a turbine base.

The operational effects of wind turbines onprotected species (with the exception of birdsand bats) relate mainly to noise and movement.Theoretically, these could affect the hunting andranging behaviour of protected species.However, such effects are widely considered notto be significant. Species that are regularlypresent or even those with a much largerterritory which includes a wind farm are thoughtto get used to such changes quite quickly.

viii Protected species legislation is largely included within the Wildlife and Countryside Act, 1981 and amendments, somespecies are given a higher level of protection at a European level through the Habitats Regulations, 1994.

ix ‘Habituation’ is the process by which individual animals show a decease in response to an environmental stimulus overtime so that they can distinguish between potentially significant and insignificant events.

x ‘homes’ can be underground, in amongst piles of rocks or dense vegetation, or in trees or watercourses.



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Wind Power in the UK

A guide to the keyissues surrounding

onshore wind powerdevelopment in the UK

Win

d Pow

er in th

e UK

Sustainable Developm

ent Comm

ission May 2005

Acknowledgements

Many individuals and organisations assisted uswith the compilation of this report and theCommission is extremely grateful to all of them.

The views expressed are those of theSustainable Development Commission.

Cover image: Niall Olds, Enviros

Published: May 2005 (revised November 2005)

Printed on material that contains a minimumof 100% recycled fibre for uncoated paper and75% recycled fibre for coated paper.

To order more copies of this report, to ordercopies of the booklet, Wind Power, YourQuestions Answered, or to find out more aboutthe work of the Sustainable DevelopmentCommission, visit our website at

www.sd-commission.org.uk

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