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PAN 45 (revised 2002): Renewable Energy Technologies

The Scottish Executive
Development Department
Planning Services

Victoria Quay
Edinburgh EH6 6QQ

Telephone: 0131-244 7546
Fax: 0131-244 7555
Brian.spiers@scotland.gsi.gov.uk
http://www.scotland.gov.uk

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30 January 2002

Dear Sir or Madam

PLANNING ADVICE NOTE 45 (Revised 2002) : RENEWABLE ENERGY TECHNOLOGIES

I enclose a copy of Planning Advice Note 45 (Revised 2002) : Renewable Energy Technologies. This should be read alongside the associated NPPG 6 (Revised 2000) : Renewable Energy Developments.

The PAN covers the characteristics of the main types of electricity generation developments, using renewable energy resources, likely to be deployed in Scotland.

The revised PAN replaces the earlier version published in 1994, up-dating information and advice on the technologies i.e. wind power, hydro-power (including shore line wave power) and energy from biomass and wastes, the significant planning issues likely to arise and how these can be addressed. It illustrates the range of such developments that have taken place in Scotland and the implications for the rural economy.

Enquiries about the content of the PAN should be addressed to Brian Spiers, 2-H91, Victoria Quay, Edinburgh, EH6 6QQ, telephone 0131 244 7546 or by e-mail to brian.spiers@scotland.gsi.gov.uk This PAN and other NPPGs and PANs can be viewed on the Planning web-site at www.scotland.gov.uk/planning Further copies of the PAN are available from Planning Services, 2H, Victoria Quay, Edinburgh, EH6 6QQ, telephone 0131 244 7543 or e-mail sandra.carey@scotland.gsi.gov.uk

Yours faithfully

ALAN DENHAM

Introduction

1. Encouraging more electricity generation from renewable sources is an integral part of both the UK and Scottish Climate Change Programmes and the Scottish Executive is committed to increasing the amount of renewable energy generated and used in Scotland. The mechanism for promoting renewable energy generation is provided through 'renewables obligations'. These are explained in more detail in paragraphs 7 to 9. The land use policy framework for achieving this is set out in the National Planning Policy Guideline (NPPG) 6 : Renewable Energy Developments published in November 2000. The purpose of this Planning Advice Note (PAN) is to support the policies in NPPG 6 by providing information and advice on the technologies for harnessing renewable energy for electricity generation. It should be noted that not all renewable energy proposals fall to be determined under the Town and Country Planning (Scotland) Act 1997 and the advice in this PAN will be equally applicable in the authorisation of proposals under Section 36 of the Electricity Act 1989 (see paragraphs 5 and 16&17).

("Renewables will play a key role in future greenhouse gas abatement and that increasingly the uptake of renewables has to be a non-negotiableelement of future energy use."

Energy : The Changing Climate, Royal Commission on Environmental Pollution. 2000)

2. In 2000 the UK Government, as part of its support for the Climate Change Programme, announced its new policy on renewable energy. The aim is to stimulate further the development of the UK renewable energy industry. The objective is that by 2010 10% of UK electricity requirements will be met from renewable sources. The policy has 5 key aims :

• to assist the UK to meet national and international targets for the reduction of emissions, including greenhouse gases;

• to help provide secure, diverse, sustainable and competitive energy supplies;

• to stimulate the development of new technologies necessary to provide the basis for continuing growth of the contribution from renewables into the longer term;

• to assist the UK renewables industry to become competitive in home and export markets and in doing so to provide employment; and

• to make a contribution to rural development.

("Renewable energy sources shall mean renewable non-fossil energy sources (wind, solar, geothermal, wave, tidal, hydropower, biomass, landfill gas, sewage treatment plant gas and biogases)"

EU Directive on "The promotion of electricity produced from renewable energy sources in the internal electricity market" Sept 2001)

3. In Scotland existing hydro schemes account for about 11% of electricity generation with new renewable energy projects under the original Scottish Renewable Obligation (SRO) arrangements adding another 2% to that figure. A further increase of 5% is proposed in Scotland under the new Renewables Obligation (Scotland) which will take the Scottish total to about 18% by 2010. Further development is envisaged beyond 2010.

Technologies not covered by this PAN

4. There are a number of renewable energy sources such as solar and geothermal that have potential to contribute to renewable energy generation and energy efficiency measures, all of which have the potential to contribute to the climate change objectives. However, these are not covered by this PAN.

5. The authorisation of renewable energy facilities such as wind turbines and wave power machines in offshore locations are outwith the jurisdiction of the Planning Act. The authorisation of such developments is currently the subject of a Scottish Executive consultation paper which suggests that the authorisation of such proposals should come within the scope of Section 36 of the Electricity Act 1989 and the associated Electricity Works (Environmental Impact Assessment (Scotland) Regulations 2000.

("Proposed Consents Process for Offshore Wind or Water Driven Generating Stations". Consultation Paper SEELLD January 2001)

6. Large-scale offshore wind farms are being developed off the Danish coast but to date there has been limited interest in UK waters. This is changing following the award of contracts by the Crown Estate for potential sites around the coast of Great Britain. One such site is in the Solway Firth between England and Scotland. Although the nature of much of Scotland's coast has tended to create the view that further large scale developments here are unlikely, technological developments and the need to exploit this resource point to more consideration being given in the future to the scope for such developments (see paragraph 14 and Case Study 1). For these reasons this PAN does not cover further details of such offshore projects. Following the current review and further guidance from SE Energy Division will follow.

The Scottish Renewables Obligation (SRO)

7. The first Order (SRO 1) under the Scottish Renewables Obligation was established in 1994 to promote the development of renewable forms of electricity generation. There have been two further Orders, SRO 2 (1997) and SRO 3 (1999). The Orders were targeted at specific technologies.

Renewables Obligation (Scotland), the ROS

8. The Utilities Act 2000 gives the Scottish Ministers executively devolved powers to set a separate renewables obligation for Scotland, and to exclude particular technologies. The renewables target in Scotland will be implemented under the Renewables Obligation (Scotland) or ROS. The ROS will oblige all licensed electricity suppliers in Scotland to obtain renewables obligation certificates sufficient to cover a specified proportion of the electricity supplied to their customers in Scotland and will come into force in April 2002. Further guidance will be issued in due course.

("The Renewables Obligation (Scotland)"

Scottish Executive Consultation Paper. July 2001)

Qualifying Renewables Technologies Under ROS

9. In contrast with the previous SRO arrangements, the Scottish Ministers will not direct which specific renewables projects at specific sites will be developed to meet the ROS target. Instead the market will, in general, take these decisions subject to obtaining permission in the normal way. Ministers will, however, be able to specify which technologies will not qualify for support under ROS. There has been debate about the use of waste in renewable energy power generation, particularly focused on the role of incineration and the future role of the existing hydro schemes. This is discussed further under the relevant technologies.

Renewable Energy Potential in Scotland

10. Scotland has significant renewable energy resources. The available wind resource could sustain a large contribution from onshore wind farms. Small hydro schemes will probably be developed and there is considerable potential in the refurbishment of existing hydro schemes. In addition, Scotland has a considerable medium term resource in the shape of forestry biomass and, in the longer term, in wave and tidal power. There currently may be an opportunity to develop a lead in wave energy and other marine power technology, including offshore wind, through indigenous marine energy expertise. The energy potential from marine power in Scotland, while not nearly as much as for wind, is quite significant on the north and west coasts and there could be an advantage in establishing a home market in the technology.

11. The Scottish Executive awarded a research contract to review the 1993 report "An Assessment of the Potential Renewable Energy Resource in Scotland". The review, "Scotland's Renewable Resource 2001" has now been published and is available on the Scottish Executive Website at www.scotland.gov.uk

The Scottish Electricity Grid and Network Connections

12. There is existing capacity to accommodate new generation in the central belt and southern Scotland but there are limitations in the north and west. A working group, chaired by energy regulator OFGEM, has reported on the many technical, regulatory and financial factors that inhibit the connection of small, decentralised generation plant (embedded generation, now referred to as "distributed generation") to electricity networks operated by the distribution network operators (DNOs).

( "Embedded generation working group report" DTI Jan 2001)

13. In addition the Scottish Executive commissioned research on the limitations of the current distribution network and the likely costs involved in upgrading. The results of this study, the "Scottish Network Study 2001" has now been published and is available on the Scottish Executive Website at www.scotland.gov.uk

Research and Development

14. Renewables research and development is the responsibility of the Department of Trade and Industry (DTI). The Government has allocated £267 million over 2001-2004 to promote renewable technologies. This includes £89 million for capital grants for offshore wind, energy crops and small scale biomass from the DTI and the New Opportunities Fund; £55.5 million for an expanded DTI R&D programme; and a further £100 million that will be allocated after completion of a report on renewable energy by the Performance and Innovation Unit in the Cabinet Office. The Scottish Executive will encourage as many good Scottish projects as possible to compete for that funding and will review the possibility of direct support for longer-term renewables technologies.

Case Study 1 : Orkney to Pioneer Wave Power

In July 2001 the Scottish Executive announced that Orkney had been selected as the preferred site for the Scottish Marine Energy Test Centre (METC). The site at Stromness was considered to provide advantages over other sites considered in terms of the available resource (wave power and tidal currents), a short distance offshore to exploit these resources, the availability of onshore facilities (offices, storage and berthing), suitable connections to power lines and sheltered water for construction. The Scottish Executive, along with Highlands and Islands Enterprise, will provide the £400,000 needed to fund phase two of the project. This phase will involve a full-scale site survey including an environmental impact assessment into the selected site at Stromness. It is anticipated that the test centre will be operational in 2002.

General Considerations

15. There are a number of general considerations that are common to all the technologies for renewable energy developments likely to arise in Scotland. These are discussed in the following paragraphs. The considerations arising from the application of specific technologies are discussed in detail in the relevant sections of this PAN.

Relationship Between Land Use Planning and Other Forms of Control

16. Electricity generation proposals over 50 MW (1 MW for hydro plant) fall to be authorised under section 36 of the Electricity Act 1989, The Electricity (Applications for Consent) Regulations 1990 (SI 1990 No. 455) and the associated Electricity Works (Environmental Assessment) (Scotland) Regulations 2000 (SSI 2000, No 320). The authorisation procedures also include provisions for a public inquiry in circumstances where relevant objections are lodged (see The Electricity (Applications for Consent) Regulations 1990 SI 1990 No. 455 and SOEnD Circular 3/1991).

17. Consent for overhead lines must be applied for and obtained separately from planning permission and there are separate procedures to deal with this under Section 37 of the Electricity Act 1989. Section 37 consent should be sought simultaneously with the planning or Section 36 consent for the development itself, in order that both can be considered together.

18. Planning and pollution control authorities have different powers and functions and these can, on occasions, overlap. It is a long established policy that planning controls should not duplicate other statutory controls, or be used to secure objectives more properly achieved under other legislation (see NPPG 1 Revised 2000). The application of this to specific technologies is discussed in the relevant sections of this PAN.

Environmental Impact Assessment

19. Renewable energy proposals, depending on their size and nature, fall to be determined under either the Town and Country Planning (Scotland) Act 1997 or under Section 36 of the Electricity Act 1989 (see paragraph 16). Different EIA regulations apply. Under the Electricity Act 1989, the relevant EIA Regulations are The Electricity Works (Environmental Impact Assessment) (Scotland) Regulations 2000; see also "Guidance on the Electricity Works (Environmental Impact Assessment) (Scotland) Regulations 2000. The provisions under the Planning EIA Regulations (the Environmental Impact Assessment (Scotland) Regulations 1999) are quoted below.

Fig 1 : EIA Projects

Schedule 1 projects

EIA is mandatory for projects which meet the descriptions of development listed below :

• Schedule 1, paragraph 2(1) - thermal power stations and other combustion installations with a heat output of 300 megawatts or more;
• Schedule 1, paragraph 9 - waste disposal installations for the incineration, chemical treatment, or landfill of hazardous waste;
• Schedule 1, paragraph 10 - waste disposal installations for the incineration or chemical treatment of non-hazardous waste with a capacity exceeding 100 tonnes a day;

• Schedule 1, paragraph 15 - Dams and other installations designed for the holding back or permanent storage of water, where a new or additional amount of water held back or stored exceeds 10 million cubic metres.

Schedule 2 projects

EIA is only required if the following are likely to generate significant environmental effects :

• Schedule 2 paragraph 3(a) - industrial installations for the production of electricity, steam and hot water (unless in Schedule 1);
• Schedule 2, paragraph 3(b) - industrial installations for carrying gas, steam and hot water;
• Schedule 2, paragraph 3(c) - surface storage of natural gas;
• Schedule 2, paragraph 3(d) - underground storage of combustible gases;
• Schedule 2, paragraph 3(h) - installations for hydroelectric energy production;
• Schedule 2, paragraph 3(i) - installations for harnessing of wind power for energy production (wind turbines);
• Schedule 2, paragraph 10(i) - dams and other installations designed to hold water or store it on a long-term basis (unless in Schedule 1);
• Schedule 2, paragraph 11(b) - installations for the disposal of waste (unless in Schedule 1)

20. There may be circumstances in which development proposals for renewable energy generation will fall within at least one of these categories. Guidance on EIA for specific technologies is given below. EIA is mandatory for all projects in Schedule 1. A Schedule 2 development must be screened to establish if it is likely to have significant environmental effects. If this proves to be the case then EIA is required. To aid the screening procedure, guidance is given in SEDD Circular 15/1999, paragraphs 36-40 where general guidance is provided, and at Annex A which gives indicative criteria where EIA is more likely to be required. Additional advice is included in PAN 58.

21. Wind farms fall within Schedule 2. If the proposed development is located within a 'sensitive area' as defined at Regulation 2(1); or involves the installation of more than 2 turbines; or the hub height of any turbine, or the height of any other structure exceeds 15 metres then the need for EIA must be considered. The likelihood of significant effects will generally depend upon the scale of the development, and its visual impact and other potential impacts. EIA is more likely to be required for commercial developments of 5 or more turbines, or more than 5 MW of new generating capacity.

22. In general, hydroelectric schemes fall within Schedule 2. However, where it involves a dam intended to store more than 10 million cubic metres of water, it is a Schedule 1 project and EIA is mandatory. If located within a 'sensitive area' as defined at Regulation 2(1); or designed to produce more than 0.5 MW; or includes a dam where the area of the works exceeds 1 hectare, then the need for EIA must be considered. In addition to the physical scale of the hydroelectric development, the potential wider impacts on hydrology and ecology should also be considered.

23. Smaller thermal power station schemes would be considered under Schedule 2, "industrial installations for the production of electricity, steam and hot water" if the proposed site is within a 'sensitive area' (as defined at Regulation 2(1); or the area of the development exceeds 0.5 hectares. Where the process involves the collection, storage and processing of hazardous or non-hazardous wastes, proximity to controlled waters (within 100 metres) is a relevant consideration and likewise the collection and storage of combustible gases.

24. The likelihood of significant effects will generally depend on the scale of the development and the nature of the potential impact in terms of discharges, emissions or odour. For installations (including landfill sites) for the deposit, recovery and/or disposal of household, industrial and/or commercial waste (as defined by the Controlled Waste Regulations 1992), EIA is more likely to be required where new capacity is created to hold more than 50,000 tonnes per year, or to hold waste on a site of 10 hectares or more.

25. Many of the issues covered by waste licensing or integrated pollution control authorisation procedures will also be within the scope of any environmental assessments undertaken in support of planning applications. In such cases it should not be assumed that because a licence or an authorisation is required for a particular activity, the activity can be excluded from the scope of an EIA. EIAs should cover all significant environmental effects of a development project.

26. Developers may undertake studies to fulfil both the objectives of the environmental impact assessment and licence or authorisation applications. To speed up the process, and where appropriate, developers should be encouraged to use the environmental statement to provide all the technical information required for all the various permissions and licences; not only planning approval.

27. When a planning authority decides that statutory EIA is not required, it is still open to them to use their powers under Article 13 of the General Development Procedure Order to request additional environmental information. In such circumstances, the list of topics included in Schedule 3 to the 1999 EIA Regulations may provide a useful guide.

Grid Connections

28. Any commercial renewable energy project will usually require a connection to the electricity distribution grid. A small sub-station is needed to transform the electricity to grid voltage (usually 11 or 33 kV.). A standard 3-wire system mounted on wooden poles would then link this sub-station to the nearest suitable point of the grid. The line could be laid underground in exceptional circumstances where visual amenity considerations were considered to be of sufficient importance.

Other Issues to be Addressed

Noise

29. Advice on Planning and Noise is given in SODD Circular 10/1999 and PAN 56. There is a perception that noise from wind turbines is a significant problem. This is not necessarily the case however and the issue is discussed in the relevant section of this PAN.

Construction Disturbance

30. The degree of disturbance caused by construction will depend on the scale and nature of the development and the length of the construction period. Public perception of construction will derive mainly from physical impact and traffic movements. Traffic movements to be expected are :

• vehicles removing spoil;
• vehicles bringing concrete for foundations;
• large vehicles (may be articulated) bringing components;
• vehicles transporting those working on the site; and
• vehicles bringing a crane to erect equipment.

In particular cases there may be advantages in using helicopters to bring in construction materials and equipment. However caution will be required near sensitive areas, such as protected bird breeding sites during the breeding season.

31. Although construction disturbance will essentially be no different from other forms of developments (and in most cases will be shorter), many developments will be sited in areas served by minor roads or involve movement of large components. In such cases, planning authorities may wish to control the number of vehicle movements to and from the site in a specified period and, where possible, the route of such movements, particularly of heavy vehicles, by imposing suitable conditions, or entering into planning agreements with the developer. Consultation with the Scottish Executive will also be necessary for movements on Trunk Roads.

32. Once the project is in operation, traffic movements to and from the site will depend on the nature of the particular development, for example, wind farms will require infrequent access, whereas biomass plants will require regular access. It will therefore be necessary to consider the on-going requirement for access during the operational life of the development. Where substantial access roads are created to facilitate construction and after are no longer required, there should be a requirement for reinstatement to that strictly necessary for the ongoing operation of the development.

33. Each technology will have its own decommissioning requirements. For most it will be sufficient to require removal of any infrastructure and restoration and revegetation of the site and access tracks. Concrete foundations may be best left in place and covered over. Where impoundment is associated with hydro schemes the drawdown zones may require reshaping to conceal former erosion edges.

Related Policy Issues

34. Policy issues related to the protection and enhancement of the natural and built heritage are set out in NPPG 14 : Natural Heritage, NPPG 5 : Archaeology and Planning and NPPG 18 : Planning and the Historic Environment. Scottish Natural Heritage (SNH) have recently issued guidance on wind farms and small scale hydroelectric schemes. Specific issues likely to arise for different technologies are set out in the appropriate sections of this PAN.

("Guidelines on the Environmental Impacts of Wind farms and Small Scale Hydroelectric Schemes ". SNH 2001)

Conditions and Agreements

35. SODD Circular 4/1998 and associated addendum (April 1999) gives advice about the use of conditions in planning permissions. SODD Circular 12/1996 covers the use of Section 75 Agreements. The Scottish Executive has recently published a research study aimed at assessing the use and effectiveness of planning agreements and their potential to deliver wider objectives. Technology-specific considerations are covered in the relevant sections of this PAN.

("The Use and Effectiveness of Planning Agreements ".

Scottish Executive Central Research Unit 2001)

Wind Power

Introduction

36. Wind power is now well established and accepted as a commercial source of electricity with no production of particulates or harmful gases. The UK has one of the windiest climates in Europe. Scotland, having a significant amount of this resource, is well placed to exploit it.

37. Generating electricity using wind power has the potential to reduce the amount of electricity from fossil fuel power stations, thus reducing emissions of harmful gases such as carbon dioxide (CO 2), sulphur dioxide (SO 2) and nitrogen oxides (NO x). For example, in 1999 UK wind farms produced over 0.5 billion units of clean electricity potentially offsetting over 430,000 tonnes of carbon emissions.

38. This section offers information and advice on the technologies and characteristics of on-shore wind generators. It is mainly concerned with larger groupings of wind turbines, referred to as wind farms. Proposed developments exceeding 50 MW will fall to be determined under Section 36 of the Electricity Act. However, much of it will apply equally to smaller scale developments, in particular the issue of visual amenity.

Case Study 2 : Hagshaw Hill, Scotland's First Wind Farm

Hagshaw Hill wind farm lies 4 km west of Douglas, Lanarkshire and was the first wind farm in Scotland under SRO1.

It received planning consent in January 1995 and has been operational since November 1995.

It was developed by Trigen Ltd and is operated by Windfarm Management Services Ltd on behalf of ScottishPower plc.

26 Bonus 600 turbines.

Rated power - 15.6 MW.

Hub Height - 45m.

Rotor Diameter - 41m.

Case study 3 : Isle of Muck Community Wind Energy Project

The Isle of Muck wind energy project, officially opened in August 2000, is intended to provide reliable and cheaper electricity for the 38 islanders.

Two 26 kW wind turbines harness the windy conditions on the island. When the wind speed drops below the required level, diesel generators automatically ensure that the electricity supply is maintained.

The initiative was funded through the local enterprise company, Lochaber Ltd., the European Partnership, the National Lottery Charities Board and the Highland Council, with donations from non-islanders, Trusts and the islanders themselves.

Income from the scheme will cover repair and maintenance and will eventually fund the replacement of the turbines at the end of their useful life in about 20 years.

The scheme was developed by ScottishPower Technology (now Ingenco Ltd) and run by Isle of Muck Power Ltd.

The Technology

The Process

39. The power produced by wind turbines depends on two key factors - the strength of the wind, and the area swept by the rotor. The energy produced is strongly dependent on the annual mean wind speed at the site. The power available increases with the cube of the wind speed. A machine on a site with a mean wind speed of 6 metres per second will produce less than half as much energy as the same machine on a site with a mean wind speed of 8 metres per second. The area swept by the rotor increases with the square of the rotor diameter, so a machine with a 15-metre diameter rotor will produce only a quarter of the power of a machine with a 30-metre diameter rotor. Advances in technology now allow turbines to operate efficiently at lower wind speeds than previously.

40. Assessing whether a particular site will harness wind power satisfactorily entails using historical meteorological data (available from the Meteorological Office) and information derived from anemometers (on masts, typically 30 metres tall, on a site for about 12 months). The data help to determine whether or not a site is technically suitable and, if it is, help to identify the best positions for wind turbines within the site. Other technical considerations will include an adequate means of vehicular access (capable of taking articulated vehicles) and the availability of a connection to the electricity distribution grid.

Fig. 2 : Components of a Wind Turbine

The turbines usually have steel towers supporting the nacelle, which houses the mechanical machinery and a device known as "the yaw mechanism", which allows the machine to turn itself towards the prevailing wind. The majority of rotor blades are made of glass reinforced plastic or wood epoxy but can be of aluminium or steel.

Characteristics

41. There are essentially two types of wind turbine, vertical and horizontal axis machines. Within each type there are various technical differences, the most obvious being the number of blades. Turbines currently preferred, or likely to be so, in Scotland in the foreseeable future are of the horizontal axis, three bladed type.

42. Wind turbines are available in a range of sizes, from small battery charging units with rotor diameters of less than a metre to very large turbines with rotor diameters greater than 70 metres rated at several megawatts.

43. Current wind power technology is based largely on the considerable experience in Denmark through several generations of development. Machines rated between 500kW and 1MW are now commonplace. The technology has now advanced beyond the 1 to 1.5MW size to 2MW machines, intended originally for use offshore but now featuring in proposals onshore.

Fig. 3 : Examples of Turbine size

44. Turbine towers are fixed to a concrete foundation about 7 metres in diameter whose surface will normally be flush with the surrounding ground. The land area actually used by the turbines is therefore very small. On land normally used for agricultural purposes, agricultural use can continue up to the edge of the foundations.

45. Wind turbines can be deployed singly, in small groups or in larger numbers in wind farms. Technical factors, which may influence the size of a development, include the physical nature of the site, and the capacity of the local electricity distribution grid. It is likely that the wind resources of the UK will be harnessed most satisfactorily using a mixture of different scales of development. While it is likely that larger developments will continue to be proposed in rural areas, smaller schemes can be expected on both urban and rural sites.

46. Grouped turbines need to be positioned, for operational reasons, so that the separation distance between individual turbines is around 5 -10 rotor diameters. This represents a compromise between compactness, which minimises capital cost, and the need for adequate separation to lessen energy loss through wind shadowing from upstream machines. Land use planning, ground conditions and operational requirements will usually result in a compromise between maximising energy capture and minimising visual impact. The improved productivity of the current generation of wind turbines is largely the result of improved technology (including better micro-siting methodologies) and higher hub heights.

47. A wind farm requires a central monitoring system, consisting of a computer, which supervises the operation of the turbines. This can be housed in a small building on-site linked to a headquarters off-site. Most modern wind farms are un-manned, with their operational status regularly checked through the central monitoring and remote link facility. There is also likely to be a slender mast with anemometers and wind vanes to provide control information for the site.

Safety Aspects

48. A possible but rare source of danger to human or animal life from a wind turbine would be the loss of a piece of the blade or, in most exceptional circumstances, of the whole blade. Many blades are composite structures with no bolts or other separate components. Even for blades with separate control surfaces on or comprising the tips of the blade, separation is most unlikely. The build-up of ice on turbine blades is unlikely to present problems on the majority of sites likely to be developed in the near future. In those areas where icing of blades does occur, fragments of ice might be released from blades when the machine is started. However, most wind turbines are fitted with vibration sensors to detect any imbalance which might be caused by icing of the blades. This enables the operation of machines with iced blades to be inhibited.

49. The possibility of attracting lightning strikes applies to all tall structures and wind turbines are no different. Appropriate lightning protection measures are incorporated in wind turbines to ensure that lightning is conducted harmlessly past the sensitive parts of the nacelle and down into the earth.

50. Companies supplying products and services to the wind energy industry operate to a series of international, European and British Standards. A set of product standards for wind energy equipment has been developed by the International Electro-technical Commission - IEC 16400. There are a number of British Standards that correspond to it, for example, BS EN 61400-1: 1995 "Wind turbine generator systems - safety requirements".

Electro-magnetic Interference

Communications Systems

51. Wind turbines (in common with all electrical equipment, including those used in the home) do produce electro-magnetic radiation and this can interfere with broadcast communications and signals. Since a large number of bodies use communication systems (some commercially sensitive or of strategic or military importance), it is impossible to obtain a definitive picture of all the transmission routes across a potential site. The Radiocommunications Agency (RA), which holds a central register of all civil radio communications installations in the UK and acts as a central point of contact, will identify any radio installations in the neighbourhood of a wind farm site, but will not identify their owners. Although the RA is obliged to pass on any enquiry to all other interested parties, who should respond to an application, an applicant for planning permission would be well advised to make direct contact with any authorities or bodies which are likely to have an interest. In addition, it may be necessary to consult the local emergency services, local authority services departments, the gas and electricity companies.

("Approximation of the Laws of the Member States Relating to Electro-Magnetic Compatibility",(89/336/EEC) The European Commission Directive of 3 May 1989)

Aircraft, Aerodromes and Technical Sites

52. The siting of wind turbines may have implications for the flight paths of aircraft and airport radar and communications systems. Major airports and technical sites (civil and military) are "safeguarded" by Directions made under the Town and Country Planning (General Development Procedure) (Scotland) Order 1992 (the GDPO).

53. These safeguarding arrangements are currently under review. New arrangements are required as a result of the Government's decision that the responsibility for safeguarding civil sites should be transferred from the Civil Aviation Authority (CAA), in the case of aerodromes, to the safeguarded aerodromes themselves and in the case of technical sites, to National Air Traffic Services Ltd. (NATS). The safeguarding of military airfields and technical sites remains the responsibility of the Ministry of Defence through Defence Estates.

("Safeguarding of Aerodromes, Technical Sites and Explosives Storage Areas". Scottish Executive Consultation Paper : March 2001)

54. The consultation paper recognises the fact that the introduction of wind powered generator turbines within the UK can create certain problems for aviation. In addition to their potential for presenting an obstacle to air navigation, wind generator turbines can pose problems for aeronautical radio stations. The rotating blades create electromagnetic effects, which can degrade the performance of aeronautical systems and cause incorrect information to be received. The amount of interference depends on the wind turbine's size, shape, construction materials and location.

55. Although aviation safety is an important issue, the primary purpose of safeguarding is to ensure that certain aerodromes can continue to operate at their existing level of activity and that, in the event of planning permission being granted, levels of operation would be able to increase without hindrance. This is in recognition of the economic importance of these aerodromes to Scotland as a whole as well as their significance to the local economy.

56. Under the proposed new arrangements planning authorities receiving applications affecting the areas identified in the (civil) safeguarding maps, will be required to consult the relevant aerodrome operator or, for en route technical sites, NATS. If the planning authority proposes not to act on objections, or not to attach conditions requested by the consultee(s), it must notify the CAA. The CAA will discuss the proposed development and/or the requested conditions with the consultee(s). If the CAA considers that the consultee(s) has raised a valid issue, it can request the Scottish Ministers to call in the application.

57. Following consideration of the consultation responses, the replacement Direction and associated Circular will be submitted for confirmation by the Scottish Parliament and further guidance will be issued thereafter.

58. In the case of a military site, the consultee is the MoD (Defence Estates). If the planning authority proposes not to act on objections, or not to attach conditions requested, it must notify the MoD. Where the MoD considers intervention is necessary, it can request the Scottish Ministers to call-in the application.

59. The Civil Aviation Authority is responsible for recording all air navigation obstructions in the UK. This record is essential for air safety. Full details of obstructions, that is any building or works extending 91.4 metres or more above ground level, are published for pilots' information and noted on aeronautical maps and charts. Planning authorities are requested to supply the CAA with information about approved new development involving obstructions as soon as permission has been granted. It is normal practice to provide warning lights on any object which extends 150 metres or more above ground level.

Case Study 4 : Safeguarding Arrangements for Prestwick Airport

A wind farm safeguarding map has been prepared by Prestwick Airport in conjunction with the Ayrshire Joint Structure Plan Committee and South Ayrshire Council. The map identifies three areas sensitive to wind farm development. The three areas seek to safeguard the flight path of planes using the airport as well as the operation of the navigational and instrument landing system in the vicinity of the airport. A wider consultation zone that extends to 40 nautical miles from the airport is also identified.

Military Low Flying

60. The Ministry of Defence uses several areas of the countryside for low flying training. The Hansard extract below indicates the current MoD position on this issue. Further information on Military Low Flying can be obtained from the MoD web-site www.mod.uk/issues/lowflying

Fig 4 : MoD Position on Wind Turbines in Operational Low Flying Areas

"In principal the MoD has no objection to wind farms. The UK has three specially designated Tactical Training Areas (TTA) that are available for authorised military Operational Low Flying (OLF) training. The three TTAs are located in Central Wales (LFA7T), North Scotland (LFA14T) and the border region of northern England / southern Scotland (LFA20T). Within these areas military fast jet and Hercules aircraft may operate at heights between 250ft and 100ft. In addition, units make use of these specifically surveyed areas to conduct specialised night training.

Flying down to 100ft is also authorised over the Electronic Warfare Tactics Range (EWTR), LFA13. The EWTR is a RAF facility made available to other NATO countries on a repayment basis, or under other special arrangements. It is located in the north of England/southern Scotland TTA. In addition to tactical radar avoidance training, the airspace associated with use of the EWTR is made available for test and evaluation flying, specialised night training and some operational low flying training. Low flying within LFA13 is associated almost entirely with operation of the EWTR.

Conclusions of a study conducted by the RAF Signals Engineering Establishment, into the Effects of Wind Generators on Radar Performance, were that wind turbines cause interference to primary surveillance radar and harm the ability to detect and track aircraft flying over wind farms. Moreover, the presence of unlit constructions of significant size would be highly dangerous to aircraft flying down to 100ft.

In the interests of flight safety, the safety of aircrew and members of the public, it is vital that any hazard to low flying aircraft are minimised. Any extraneous distraction or possible reduction in external support capabilities, such as that provided by ground radar, can have a deleterious effect upon aircraft safety, and thus the safety of aircrew as well as those on the ground.

It is, therefore, MOD opinion that obstacles in excess of 100ft in height, unlit by night and with the ability to cause interference to radar, have the potential to create an acute safety hazard to aircraft engaged in operational low flying , tactical radar avoidance training, specialised night flying and test and evaluation flying, however, each case has to be considered on its merit."

Dr Lewis Moonie MP Parliamentary Under Secretary of State for Defence
(Hansard 22 March 2001).

Fig 5 : UK Military Low Flying System

Television Reception

61. There may be a particular concern that turbines will interfere with television reception. Considerable experience has shown that when this occurs it is of a predictable nature and can generally be alleviated by the installation or modification of a local repeater station or some cable connection. The interference effects can also be reduced by local site plan changes and this possibility should be discussed with the transmitter operators.

Proximity to Roads and Railways

62. Pre-application discussions are advisable with the Scottish Executive [Road Network Management & Maintenance Division] for developments in proximity to trunk roads and the local roads authority for all other publicly maintained roads. This is particularly important for the movement of large components (abnormal load routing) during the construction period, periodic maintenance and for decommissioning. Subsequent planning applications may require consultation with the relevant roads authority as required by the GDPO. In the case of railway lines, the authorities are Railtrack (area Civil Engineering) for operational lines and Railtrack Property Board for non-operational lines.

63. Although wind turbines erected in accordance with best engineering practice should be stable structures, it may be advisable to achieve a set-back from roads and railways of at least the height of the turbine proposed, to assure safety. Driver distraction may, in some circumstances, be a consideration. The provision of appropriately sited lay-bys can be helpful.

Shadow Flicker

64. Under certain combinations of geographical position, time of day and time of year, the sun may pass behind the rotor and cast a shadow over neighbouring properties. When the blades rotate, the shadow flicks on and off; the effect is known as "shadow flicker". It occurs only within buildings where the flicker appears through a narrow window opening. The seasonal duration of this effect can be calculated from the geometry of the machine and the latitude of the potential site. Where this could be a problem, developers should provide calculations to quantify the effect. In most cases however, where separation is provided between wind turbines and nearby dwellings (as a general rule 10 rotor diameters), "shadow flicker" should not be a problem.

Noise

65. Well designed wind turbines are generally quiet in operation. The table below gives an indication of the noise generated by wind turbines compared with other everyday activities.

Fig 6 : Indicative Noise Levels

66. There are two quite distinct types of noise sources within a wind turbine. The mechanical noise produced by the gearbox, generator and other parts of the drive train; and the aerodynamic noise produced by the passage of the blades through the air. Since the early 1990s there has been significant reduction in the mechanical noise generated by wind turbines and it is now usually less than, or now of a similar level to, the aerodynamic noise. Aerodynamic noise from wind turbines is generally unobtrusive; it is broad band in nature and in this respect similar to, for example, the noise of wind in trees.

67. Wind generated background noise increases with wind speed, and at a faster rate than wind turbine noise increases with wind speed. The difference between the noise of the wind farm and the background noise is therefore liable to be greatest at low wind speeds. Varying the speed of the turbines in such conditions can if necessary, reduce the sound output from modern turbines.

68. The Report, "The Assessment and Rating of Noise from Wind Farms", describes a framework for the measurement of wind farm noise and gives indicative noise levels thought to offer a reasonable degree of protection to wind farm neighbours, without placing unreasonable restrictions on wind farm development or adding unduly to the costs and administrative burdens on wind farm developers or planning authorities. The report presents a series of recommendations that can be regarded as relevant guidance on good practice.

Fig 7 : Recommended Good Practice on Controlling Noise from Wind Turbines

From : " The Assessment and Rating of Noise from Wind Farms" (ETSU for DTI 1996).

• The current practice on controlling wind farm noise by the application of noise limits at the nearest noise-sensitive properties is the most appropriate approach;

• Noise limits should be applied to external locations and should apply only to those areas frequently used for relaxation or activities for which a quiet environment is highly desirable;

• Noise limits set relative to the background noise are more appropriate in the majority of cases;

• Generally, the noise limits should be set relative to the existing background noise at the nearest noise-sensitive properties and that the limits should reflect the variation in both turbine source noise and background noise with wind speed;

• It is not necessary to use a margin above background noise levels in particularly quiet areas. This would unduly restrict developments which are recognised as having wider national and global benefits. Such low limits are, in any event, not necessary in order to offer a reasonable degree of protection to wind farm neighbours.

• Separate noise limits should apply for day-time and for night-time as during the night the protection of external amenity becomes less important and the emphasis should be on preventing sleep disturbance.

• Absolute noise limits and margins above background should relate to the cumulative effect of all wind turbines in the area contributing to the noise received at the properties in question. Any existing turbines should not be considered as part of the prevailing background noise.

• Noise from the wind farm should be limited to 5dB(A) above background for both day- and night-time, remembering that the background level of each period may be different.

• The L A90,10min descriptor should be used for both the background noise and the wind farm noise, and that when setting limits it should be borne in mind that the L A90,10min of the wind farm is likely to be about 1.5-2.5dB(A) less than the L Aeq measured over the same period. The use of the L A90,10min descriptor for wind farm noise allows reliable measurements to be made without corruption from relatively loud, transitory noise events from other sources.

• A fixed limit of 43dB(A) is recommended for night-time. This is based on a sleep disturbance criteria of 35dB(A) with an allowance of 10dB(A) for attenuation through an open window (free field to internal) and 2dB(A) subtracted to account for the use of L A90,10min rather than L Aeq,10min.
• Both day- and night-time lower fixed limits can be increased to 45dB(A) to increase the permissible margin above background where the occupier of the property has some financial interest in the wind farm.

• In low noise environments the day-time level of the L A90,10min of the wind farm noise should be limited to an absolute level within the range of 35-40dB(A). The actual value chosen within this range should depend upon; the number of dwellings in the neighbourhood of the wind farm; the effect of noise limits on the number of kWh generated; and the duration of the level of exposure.

• For single turbines or wind farms with very large separation distances between the turbines and the nearest properties, a simplified noise condition may be suitable. If the noise is limited to an L A90,10min of 35dB(A) up to wind speeds of 10m/s at 10m height, then this condition alone would offer sufficient protection of amenity, and background noise surveys would be unnecessary.

Power Lines

69. Power lines connecting the individual turbines to the on-site substation will be underground. To avoid visual confusion, routing and design of power lines, connecting the wind farm substation to the electricity distribution system, will require sensitive treatment (see paragraph 28).

Siting in the Landscape

70. In order to minimise wind speed variations, commercial wind farms need to be located in areas of relatively smooth and rounded relief. They also require ready access to the electricity transmission and distribution system unless they are intended solely for private use. The current generation of turbines is capable of operating at lower wind speeds than previously which has the effect of increasing the types of areas (and landscapes) that may attract developer interest. Public concern over the visual impact of past (and many current proposals) has been a recurring feature. Experience, following construction, suggests that much of the fear is unnecessary. It is, nevertheless, an issue that continues to need to be addressed.

Case study 5 : Public Attitudes Towards Wind Farms in Scotland

This research examined the attitudes of local populations towards the four operational wind farms in Scotland (Hagshaw Hill, South Lanarkshire; Windy Standard, Dumfries and Galloway; Novar, Highland; and Beinn Glas, Argyll and Bute). The major aim of the research was to examine how residents feel about the existence and proximity of their local wind farm. An important objective was to identify whether, and to what extent, residents' views of wind farms are based on actual experience or perception formed through the media, word of mouth or other sources.
Respondents were generally positive about wind farms. Those who lived nearest a wind farm were more likely to provide positive responses when asked about the wind farm than those in the other areas. For example, while 67% of respondents overall said that there was something they liked about the wind farm, this proportion increased to 73% of those living in the area closest to the wind farm.

The proportion of respondents who had anticipated problems prior to the development (40%) was far higher than the proportion who actually experienced problems after the development (9%). Actual noise caused by the turbines or the visual impact of the wind farm did not feature as issues for the majority of respondents.

Public Attitudes Towards Wind Farms in Scotland.
Scottish Executive Central Research Unit. 2000

71. Scotland has a variety of landscapes. Some will be able to accommodate wind farms more easily than others, on account of their landform and relief and ability to limit visibility. Some are highly valued for their quality. There are no landscapes into which a wind farm will not introduce a new and distinctive feature. Given the Scottish Ministers' commitment to addressing the important issue of climate change and the contribution expected from renewable energy developments, particularly wind farms, it is important for society at large to accept them as a feature of many areas of Scotland for the foreseeable future.

72. This is not to suggest that areas valued for their international or national landscape and nature conservation interest will have to be sacrificed. Nor that elsewhere, attempts to lessen the impacts by integrating the development into the surrounding landscape would not be worthwhile. On the contrary, it emphasises the need for account to be taken of regional and local landscape considerations. Development that has been carefully sited and tied into the surrounding landscape will still be visible but the impact will be less than had this effort not been made and the development left less well related to its surroundings.

73. The landscape and visual impact of wind turbines is influenced by :

• land form and landscape characteristics;

• number, size and layout of turbines

• how the turbines relate to the skyline

• design and colour;

• access tracks; and

• ancillary components like power lines and substations.

74. The capacity of the landscape to accommodate wind farm development depends on two considerations :-

• the degree of impact the development will have on the existing character of the landscape; and

• the extent to which this impact can be modified and reduced by design.

The ability of the landscape to absorb development depends on careful siting, the skill of the designer, and the inherent characteristics of the landscape such as landform, ridges, hills, valleys, and vegetation.

75. A cautious approach is necessary in relation to particular landscapes which are rare or valued, such as National Scenic Areas and proposed National Parks and their wider settings. Here, it may be difficult to accommodate wind turbines without detriment to natural heritage interests. In a regional context care should also be exercised within Areas of Great Landscape Value and Regional Parks. Other landscapes are not especially valued and a significant change in some landscapes may be considered acceptable. For example, areas recovering from past degradation, such as those semi-rural areas of the central belt affected by historic mineral extraction, may be appropriate areas to accommodate wind farm development.

76. Scottish Natural Heritage has carried out a comprehensive national programme of Landscape Character Assessment. These assessments cover all of the council areas of Scotland and broadly define the variety of Scotland's landscape types. While not directed specifically at potential wind farm developments, they identify landscape characteristics that may be sensitive to wind farm development. Within such broad areas there will be areas of varying landscape characteristics with different implications for development.

77. Three pilot projects are being undertaken by SNH, in conjunction with the planning authorities in Argyll & Bute, Highland and Ayrshire and Lanarkshire. These will assess the landscape capacity to accommodate wind farm developments and are intended to inform the preparation of development plan policies and the possible identification of areas of search.

Visual Impact

78. Turbines in wind farms are likely to be tall, frequently located in open land, and therefore likely to be highly visible. Domestic turbines will be smaller. It will normally be unrealistic to seek to conceal them. Developers should seek to ensure that through good siting and design, landscape and visual impacts are limited and appropriate to the location. The visual effect will be dependent on the distance over which a wind farm may be viewed, whether the turbines can be viewed adjacent to other features, different weather conditions, the character of the development and the landscape and nature of the visibility. The following is a general guide to the effect which distance has on the perception of the development in an open landscape.

Fig 8 : General Perception of a Wind Farm in an Open Landscape

79. The visual impact of wind farms will be affected by their siting and layout in relation to local land form and landscape characteristics, and the qualities of the specific site, as well as by the number of turbines. Different layouts will be appropriate in different circumstances. For example, grouped turbines can normally appear acceptable as a single, isolated feature in an open, undeveloped landscape, while rows of turbines may be more appropriate in an agricultural landscape with formal field boundaries. Although wind farms may be complex, they should not appear confusing in relation to the character of the landscape. Ideally they should be separate from surrounding features to create a simple image. The design of each development must be appropriate to its site.

80. The style and colour of turbines may also be relevant. Experience suggests that solid towers appear less complex than lattice and tapering towers are generally regarded as being more elegant than cylindrical. In terms of colour, white or off-white is generally preferred, but other colours may be acceptable in appropriate circumstances. A semi-matt surface is required to reduce the reflection of light. However, colour choice can not be a substitute for good siting and design.

81. Ancillary elements also need to be fully addressed, as their impact can often be as significant as those of the turbines. Access tracks should be routed and designed to minimise both visual and habitat impacts. This can be minimised by careful route selection, which takes account of layout and appropriate surfacing material together with the impact of cuttings, embankments and drainage channels. Managing problems of erosion and providing for reinstatement of vegetation along the track is essential. Power lines, fencing, buildings and anemometer masts should be located and designed in a way which minimises clutter.

82. There are a number of techniques which may be used to inform visual assessment of a proposed development :

• a zone of visual influence map will show where a wind farm may be seen from;
• viewpoint analysis based on key viewpoints throughout the surrounding area;
• computer generated wireline diagrams will indicate how wind turbines will appear from specific viewpoints;
• photo- and video montages are images whereby an impression of a proposed development is superimposed upon an actual photograph or video of the proposed site.

All of these have strengths and limitations.

("Guidelines for Landscape and Visual Impact Assessment" published by SPON (1995) on behalf of the Landscape Institute and the Institute of Environmental Assessment (now the Institute of Environmental Management and Assessment). A second Edition is due in March 2002.)

83. In comparison with other, well-established, forms of development in the countryside, wind turbines are relatively unfamiliar, prominently vertical and have the significant characteristic of movement. Individually or in groups, they will be distinctive features in the landscape. The visual impact of wind turbines must be assessed with these characteristics clearly in mind.

Birds and Habitats

84. Experience indicates that many bird species and their habitats are unaffected by wind turbine developments and the impact of an appropriately designed and located wind farm on the local bird life should, in many cases, be minimal. To date, the most common concern has been the risk of "bird strike" i.e. birds flying through the area swept by the blades and being hit, causing injury or death. This will depend on a number of considerations such as, the particular species and numbers, the nature of the bird flight and any relevant seasonal patterns. Most birds in flight can be expected to take action to avoid obstacles but different species will vary in their reaction (see Fig.9). However, some areas in Scotland are important for a variety of bird species protected under the EU and UK legislation (SPAs, SACs and SSSIs) These could represent potential constraints to wind farm development. As indicated in NPPG 6 the importance of complying with international and national conservation obligations must be recognised and wind farms should not adversely affect the integrity of designated sites. Protected species, such as eagles and hen harriers, occupy many areas outwith designated sites and are protected across Scotland. These factors have to be considered against the positioning and size of turbines, including the size of the area swept by the blades in relation to the air space used by the birds in the vicinity of the development.

("European Protected Species, Development Sites and the Planning System - Interim Guidance for Local Authorities on Licensing Arrangements". Scottish Executive Environment Group Oct 2001)

85. In addition, under the EC Habitats Directive, other species or habitats of special interest may be present. For example montane and bog habitats can be adversely affected by track construction unless attention is paid to minimising impact on the hydrology of the site. They may also be affected by any changes in land management which may be brought about as a consequence of improved access.

86. Developers should instruct their ecological advisers to enter into early discussions with SNH about the presence and importance of species and habitats in and around their proposed development site. Discussions should assess how serious the problems are and the scope for taking ameliorative action or seeking alternative sites nearby.

87. SNH, in consultation with the British Wind Energy Association (BWEA), is preparing a " Methodology for assessing the effect of wind farms on ornithological interests". In addition ETSU have published a report " Cumulative effects of wind turbines" in which Section 3 deals with "Cumulative effects on birds". Both will be of use to developers when assessing the potential impact of proposed developments on bird life. Royal Society for the Protection of Birds (RSPB), World Wildlife Fund (WWF), English Nature and BWEA have also published " Wind Farm Development and Nature Conservation". While intended for an English audience, it contains material that is equally relevant in a Scottish context.

88. The risks of disturbance to bird species during construction and operation of the wind farm is also an important consideration. For some species this is of greater potential significance than collision mortality.

Fig 9 : Examples of Bird Species Sensitivity

Golden Eagles

Golden eagles, during the breeding season, tend to centre much of their activities within 2-3km around the nest site and on ridges nearby. Hence terrain close to the nest site will tend to be most sensitive to disturbance from / collision with developments. Many areas will have only one pair but some may have several. In areas with many adjoining eagle pairs, the impact of an occasional casualty on the eagle population may be less significant than in areas with only one or few pairs. (See Case Study 6)

Geese & Swans

The risks to barnacle geese, whitefront geese and whooper swans are likely to arise mainly through flights between feeding areas and between feeding and roosting grounds. Distances involved are highly variable between species and locality. Geese fly in typical V skeins and their ability to avoid obstacles depends on the alertness of the lead bird. It is likely to be more difficult to accommodate developments in areas which contain nationally or internationally important concentrations of birds, than areas where these birds are present but for which important concentrations are not recorded.

Harriers & Owls

Where hen harriers and short-eared owls are present, only a small percentage of the terrain is likely to offer conflicts between development and the birds. Both species make use of a wide range of moorland habitats, tending to nest in areas with long heather and hunt over rough grassland and flush-dominated plains. However, there is considerable variation in habitat use by these species. Male hen harriers are probably most vulnerable to collision while displaying, and inexperienced juveniles may find it difficult to avoid turbine blades.

Divers

Black and red throated divers are potentially vulnerable where a development might impede flight between breeding and feeding areas. Black-throated divers tend to nest in large lochs and feed in these or in nearby lochs. They fly low as they take off from lochs. The identification of flight lines requires investigation when development is proposed. Red-throated divers nest in small lochs and lochans. They tend to feed in the sea, so flightlines are more likely to be predictable and occur on the seaward side of these nesting areas. Divers appear to have relatively poor manoeuvrability. Flight lines, around nesting and when approaching and leaving feeding areas, tend to be low and impacts with developments are possible within a radius of 0.5 to 1.0 km from such areas.

Case Study 6 : Beinn an Tuirc, Safeguarding Eagles by Habitat Management

Beinn an Tuirc wind farm, situated on the west coast of Scotland in Kintyre will be one of the most productive wind farms owned by ScottishPower. However, the site forms part of the territory for a pair of golden eagles, a species listed on Schedule 1 of the Wildlife and Countryside Act 1981 and Annex I of the EU Directive on the Conservation of Wild Birds. When the wind farm was being developed and before the planning application was made, it was clear that the golden eagles were occupying a marginal territory where food resources were scarce. The birds have only bred successfully twice in the last 15 years and this is probably due to massive declines in prey availability. This is thought to be closely linked with a twelve fold increase in the forest area over the last 12 years.

The proposed wind farm site was not an important hunting area for the golden eagles although the birds had been seen in the vicinity at certain periods during the year. It was decided that although the risk of an eagle colliding with a wind turbine was minute, the development would further stress an already struggling pair of eagles. To mitigate against the possibility of an eagle collision but more importantly, to improve the overall situation for the golden eagles, ScottishPower developed an innovative habit management plan to increase prey availability within the eagle territory. The scheme was developed by ScottishPower's consultant ornithologist and is managed by a full time ranger who reports to the Habit Management Committee with representatives from SNH, RSPB and Argyll & Bute Council. Large scale removal of immature plantation, forestry, heather management and the creation of prey "hotspots" will not only help to shift eagle activity away from the wind farm but will make the eagle territory sustainable in the longer term.

Cumulative Effects

89. The cumulative impact of a number of neighbouring developments may also be a relevant consideration. The nature and character of the location, and the landscape in which a development is located, will in part determine the acceptability or otherwise of siting proposals in proximity to each other.

90. A number of factors have influenced the current geographic distribution of wind farm proposals in Scotland, for example :

• the distribution of the viable wind resource;
• technical and economic constraints to the viability of exploiting different wind speeds;
• electricity grid access constraints;
• protected areas;
• planning policy.

These have tended to focus developments in a relatively limited number of areas. However there have been few instances where cumulative effect has had to be addressed but with more proposals coming forward this could change.

("A Guide to Assessing the Cumulative Effects of Wind Energy Development" W/14/00538/REP ETSU 2000)

91. The cumulative effects of wind farm development can arise as the combined consequences of:

• an existing wind energy development and a proposed extension to that development;
• proposals for more than one wind energy development within an area;
• proposal(s) for new wind energy development(s) in an area with one or more existing development(s);
• any combination of the above.

In assessing cumulative effects, it is unreasonable to expect this to extend beyond schemes in the vicinity that have been built, those which have permissions and those that are currently the subject of undetermined applications.

("Beinn An Tuirc :Assessment of Effects on the Landscape Resource and on Visual Amenity". Special report by Turnbull Jeffrey Partnership for ScottishPower June 1998)

Decommissioning, re-equipping and replacement

92. Wind turbines can be decommissioned and sites cleared and restored easily and rapidly. This should be covered in the conditions and/or legal agreement accompanying the consent and will be triggered by the expiry of the consent or in the event of the project ceasing to operate for a specified period. Planning authorities should satisfy themselves that funding for decommissioning will be available when required.

93. It is likely that the duration of the consent will be linked to the expected operational life of the turbines. However during this period, proposals may be forthcoming to extend the life of the project by re-equipping or to replace the original turbines with new ones. While there are obvious advantages in utilising established sites, such cases will have to be determined on merit and in the light of the then prevailing policy and other relevant considerations.

Hydro Power (and Shore Line Wave Power)

Introduction

94. Hydroelectric developments offer a clean source of electrical energy with a steady output, with no production of particulates or harmful gases. A scheme with a capacity of 100kW would typically supply enough electricity for about 150 homes. If this displaced electricity generated by currently operating fossil-fuel power stations, it would save the emissions of around 400 tonnes per year of carbon dioxide, as well as around 5 tonnes of sulphur dioxide and 2 tonnes of nitrogen oxides.

95. Major existing hydro schemes in Scotland are usually based on a dam and storage reservoir and currently generate about 11% of Scotland's electricity. New hydro developments are likely to be much smaller and not require large storage reservoirs. The key aspects of the economics of hydro are the initial large capital outlays. However, this is mitigated by the long lifetime, high reliability and availability of plant, low running costs and no annual fuel costs.

96. Under the ROS, it is the intention to extend eligibility to include the output of refurbished hydroelectric plant of up to 20MW capacity and new hydro plant of any capacity. Very small hydro schemes (1.25MW DNC or less) will be eligible without the need to refurbish.

97. This section provides information on the technology and characteristics of hydroelectric developments and advice for handling these as planning and environmental issues in development plans and planning applications. It is concerned mainly with small-scale schemes often involving small-scale storage. It also includes advice on shoreline wave power developments as these fall within the control of the Planning Acts and are significantly different in character from offshore wave projects.

Case Study 7 : Loch Tarbert Hydro Scheme

Located on the north side of Glen Tarbert near the village of Strontian, this SRO2 'run of river' scheme commissioned in 2001, utilises two small tributaries of the River Tarbert to generate 840kW, enough power for nearly 1,000 homes.

Bypasses at the intakes ensure that the tributaries always contain the agreed residual flows. Buried pipelines connect the intakes to the turbine house and a tail race returns the water back to the main stream.

On this steep, remote site, low-impact methods were used in construction. These included the use of helicopters to deliver pipes to the steeper sections and careful rehabilitation and replanting. As part of the landscape restoration programme, very careful attention was paid to ground recovery on the pipeline route and the landscaping around the turbine house. This involved the planting of many trees in association with a wider planting programme by the landowner.

The Technology

The Process

98. The process of harnessing waterpower is well established. Water flowing from a higher to a lower level is used to drive a wheel or turbine, producing mechanical energy. This energy may be used for a variety of purposes, including the generation of electricity. In simple terms, power output is related to the volume of water available, and the vertical distance through which it falls. Similar power can be obtained from a large quantity of water falling a small vertical distance, or from much less water falling a greater distance. In the first case a larger turbine is required; in the second case, the plant will be smaller. To provide sufficient depth of draw off the water, a natural pool is required or a headpond must be created with a weir. A conduit then conveys the water from the intake in the pool or headrace to the turbine. The conduit may be an enclosed pipe (or penstock) or an open channel, often called a headrace.

Characteristics

99. The essential elements in a typical hydroelectric scheme are discussed below. The scale and physical form of each of these elements will depend heavily upon local environmental conditions.

The Headworks

100. A reliable supply of water is clearly a pre-requisite for a viable hydro scheme. Rivers with large variations in flow will be unsuitable unless a holding reservoir is constructed to store water at times of excess. The water must also be sufficiently deep at source to enable the supply to be drawn off via an intake.

101. There are two principle types of headworks :

• Run-of-river - no (or negligible) water storage upstream of the weir i.e. the output from the turbine is proportional to the flow of the river.

• Storage - the intake structure is generally larger and is used to store water so that power from the turbine(s) can be timed to meet demand from consumers.

102. The intake normally comprises a trash screen of vertical or sloping bars to trap floating debris and a sluice gate to regulate the flow of water to the turbine. Some trash screens, which needs to be kept clear of debris on a regular basis, are designed to require virtually no maintenance through 'passive' design rather than automatic / active cleaning (e.g. over washed screens). A fine mesh screen may also be installed over the intake at certain times of the year to prevent fish being drawn into the supply pipe.

103. The intake structure is normally contained in a modest concrete housing set into the bank of the river. Where the water level needs to be raised in order to ensure a regular supply, the headworks will also include an artificial weir, usually of concrete or stone construction. As well as providing a water supply of suitable depth, the headpond behind the weir can help to sustain supplies to the turbine when the river is temporarily low.

The Headrace

104. Water is carried from the headrace to the turbine house by an enclosed pipe (penstock), an open channel (millrace, leat or lade), or by a combination of these. Depending on local circumstances, the distance between the headrace and the turbine house can vary from a few metres to one kilometre or more. New schemes using a high head of water will tend to use an enclosed or buried pipe. Some refurbishment schemes may use existing open channels.

105. A headrace pipe might be metal, plastic, concrete or made of a composite material. The range of diameter sizes for future run-of-river medium and high-head hydro schemes in Scotland is likely to be from 200 to 1500mm. A valve is incorporated close to the turbine house to enable the water supply to be regulated when required. The pipeline will be anchored securely to the ground, particularly at bends and junctions, and can be buried at places where it would otherwise limit access to land or cross areas of landscape sensitivity.

106. Open channels may be unlined, or lined with clay, concrete or plastic. They will usually incorporate a second sluice gate close to the turbine house, to divert or channel water back to the main stream when the turbine needs to be stopped.

107. The turbine house contains the turbine, the generator and associated electrical equipment. For a typical small-scale hydro scheme, the turbine house will be similar in size to a domestic double garage. The turbine will be sited to optimise the trade-off between the length of the headrace and the drop in water level, but there is a degree of locational flexibility. Where feasible, a turbine house may be partially buried. In order to minimise the length of the tailrace, the turbine house will normally be situated close to the watercourse. In visual terms the turbine house will often be the most prominent built element in a small-scale hydro scheme. Its design and location are thus significant planning considerations and are considered further below. (See paragraphs 116-120)

The Tailrace

108. After driving the turbine, water is returned to its natural course via the tailrace. Where the turbine house is close to the watercourse, the tailrace will take the form of a short open channel. In other cases it will be of similar construction to the headrace. As slow-moving water can impair the efficiency of the turbine, the tailrace should have a gradient sufficient to encourage a swift discharge of water.

Controls Under Other Legislation

109. A proposal to construct or operate a hydro-electric station with a capacity of more than 1 MW must be submitted to the Scottish Ministers for consent under section 36 of the Electricity Act 1989. Before applying, an applicant must consult the Fisheries Committee, which advises on possible damage to fisheries or fish stocks. The current Scottish Executive intention, under "Proposals for Abolition or Reform of Public Bodies", is that the Fisheries Committee be abolished and its functions passed to the Inspector of Salmon and Freshwater Fisheries. Since this Committee is appointed by statute under the Electricity Act 1989, abolition will require a change of legislation when the legislative timetable allows.

110. The risk to all fish can be minimised by careful design and adjustment of the seasonal operating schedule of the plant. Some types of turbine (such as low to medium head crossflow designs) can oxygenate the river water and may thereby benefit the fish population. Where necessary, dams and weirs should include structures which allow the free passage of migratory fish and afford fish and other freshwater animals protection from the turbines.

("Notes for Guidance on the Provision of Fish Passes and Screens for the safe passage of Salmon". SOAFD July 1995.)

111. The Salmon (Fish Passes and Screens) (Scotland) Regulations 1994 require dams to have an adequate fish pass and all off-takes, whether or not associated with a dam, to be screened to protect the passage of salmon (and sea trout). The Scottish Office Agriculture and Fisheries Department issued non-statutory guidance notes, to accompany the Fish Pass Regulations, to assist owners of dams and weirs on the practical aspects of their implementation. It should be noted that while the Regulations apply to proposals dealt with by planning authorities, they do not apply to dams or off-takes which are authorised by the Scottish Ministers under Acts which provide that they can have regard to the arrangements for the safe passage of salmon and sea trout when authorising the scheme e.g. under the Electricity Act 1989.

("The Salmon (Fish Passes and Screens) (Scotland) Regulations 1994". SI 1994/2524.)

112. Each District Salmon Fishery Board (DSFB) has statutory powers and duties in relation to the management and protection of salmon fisheries within its district. Consultation with the local DSFB should be undertaken immediately a hydro scheme is proposed and throughout the planning process. The local DSFB should be consulted on fish passes and exclusion devices in their area as requirements are generally site specific.

113. The Scottish Environment Protection Agency (SEPA) has a duty to promote the cleanliness of controlled waters and to conserve, so far as practicable, water resources. Consultation with SEPA should therefore be undertaken for all proposed hydro developments, both small-scale projects covered by planning legislation and larger schemes authorised under the Electricity Act 1989. The potential effect of construction works on water quality should be borne in mind. Under the Control of Pollution Act 1974 (as amended), it is an offence to cause or knowingly permit any poisonous, noxious or polluting materials or any solid waste matter to enter inland or coastal waters.

114. The EC Water Framework Directive (2000/60/EC) establishes a new framework for the management and protection of Scotland's natural water environment, including the rivers and lochs which provide the resource on which hydroelectric schemes are based. The implications of the Directive and the way it will be implemented through Scottish legislation in the proposed Water Environment Bill will have implications for hydro schemes.

("Rivers, Lochs, Coasts : The Future for Scotland's Waters". Scottish Executive Consultation Paper June 2001.)

115. The development of hydroelectric power generation schemes should be achieved in a manner which is compatible with the many other uses to which a river is put. Early liaison between the developer, planning authority, SNH, SEPA and the DSFB is essential to ensure that the proposals do not detract from the existing value and interest of the watercourse and its surroundings.

Siting in the Landscape and Design Considerations

116. As with several renewable sources of energy, it is usually only possible to exploit hydropower resources where technically the potential exists. Hydro schemes do however enjoy a limited locational flexibility to the extent that the precise siting of the headworks and, in particular, the turbine house, can sometimes be influenced by non-operational factors, including local landscape characteristics.

117. In general terms, it will be desirable to choose a location for the development where the built elements can be integrated into the landscape. Where rivers are lined with trees, for instance, it will be relatively simple to conceal the hydropower facilities, particularly if the existing woodland cover is supplemented by new planting. Where the development is taking place in a more open location, built elements should either be designed to be as small as possible, having regard to operational considerations, or should be designed to contribute positively to the landscape. In the case of schemes proposed for hillsides or other prominent locations, the landscape impact of the development, in close and distant views, should be appraised.

118. In some cases, the visual impact of the development can be minimised by siting the turbine house away from the headworks. However, the greater this separation is, the longer and potentially more prominent will be the headrace connection between the two. There will also be significant cost implications. The remote siting of a turbine house will rarely be justified by landscape considerations alone, and can become self-defeating if the headrace pipe or channel becomes a visually obtrusive feature in its own right. In many cases it will be advantageous to underground pipelines from the intake to the turbine house but careful restoration of the ground is necessary. Preferably, access tracks to weirs should be reinstated once the construction stage has been completed.

119. Although the foreseeable hydro developments will generally be small scale, their waterside location will, in some cases, place them in areas valued for their natural and/or cultural significance. Such schemes can operate for many decades, and their principal built elements will often become permanent additions to the landscape. In some circumstances, weirs, fish ladders and headrace channels can become features of interest in their own right, attracting visitors.

120. For these reasons, planning authorities may reasonably insist on a high standard of design. Particular attention may be required to the architectural quality of built elements, the choice of building materials and the manner in which the development is integrated with its surroundings. Measures to minimise the visual impact of headrace pipes and power lines should be considered carefully at the design and planning application stages.

Aquatic Habitats and Species

121. In designing a hydro scheme, account needs to be taken of the fact that different species will be affected in different ways and that some species, such as the freshwater pearl mussel, are protected under the EC Habitats Directive. Discussions with SNH will provide guidance on the species which require to be considered in a particular location. Experience has shown that by careful design it is possible to reconcile hydro schemes with conservation of the natural heritage.

Construction Disturbance

122. In general, the construction impact of a hydropower scheme will be no different to that of other developments of similar size. However, construction in or beside a river or loch may cause the water to become clouded with silt or mud. Before granting planning permission for a hydro project, the planning authority may, in consultation with SEPA and SNH, request that the developer specifies the site management measures that will be adopted to minimise this problem.

Case Study 8: Loch Poll hydroelectric Scheme

DTI's New and Renewable Energy Programme is supporting a project to monitor the environmental impact of a small hydro scheme currently being developed at Loch Poll in the Scottish Highlands. The aim is to assess the scheme's effects during and after construction by comparison with the baseline situation. By generating information on this subject, the monitoring project will help hydro scheme design in the future, particularly community-based renewables projects.
Loch Poll is a 0.24 MW hydro scheme (commissioned in Autumn 2000). The scheme lies partly within a potential Special Protection Area (pSPA), protected under the European Wild Birds Directive because it supports breeding black-throated divers. In addition, one of the rivers affected by the scheme contains a breeding population of freshwater pearl mussel, one of only 50 known to be remaining in Scotland. It is also within the Assynt-Coigach National Scenic Area (NSA).

The monitoring project brings together a number of organisations : Highland Light & Power Ltd; the Assynt Crofters Trust; the West Sutherland Fisheries Trust; Scottish Natural Heritage; the European Regional Development Fund; Highlands & Islands Enterprise; the Highland Council; and the RSPB.

Highland Light & Power is contracted to build the project and manage it for the 15 year life of the SRO contract, at the end of which the asset will transfer to ownership of the Assynt Crofters Trust.

Shoreline Wave Power

123. Additional to conventional hydroelectric power, the interface between the sea and the land has considerable energy generation potential. It does however differ from offshore wave and tidal in that it is within the land use planning regime. The main device deployed world-wide is the Oscillating Water Column (OWC). This consists of a partially submerged, hollow structure that is open to the sea below the water line. This encloses a column of air on top of a column of water. Waves cause the water column to rise and fall, which alternatively compresses and depressurises the air column. This trapped air is allowed to flow to and from the atmosphere via a Wells turbine, which has the ability to rotate in the same direction regardless of the direction of the airflow. The rotation of the turbine is used to generate electricity.

124. Three projects were awarded contracts under the third round of the Scottish Renewables Obligation (SRO3). One of these is the LIMPET (Land Installed Marine Powered Energy Transformer) - a 500kW shoreline OWC on Islay. This device was commissioned in the Spring of 2001 and replaced a prototype shoreline 75kW OWC which operated successfully for 10 years.

Case Study 9: The Islay Project

The World's first commercial wave power station has been commissioned in Scotland near Portnahaven, Islay, the first time that wave-generated electricity has been fed into the electricity distribution network on this scale. The LIMPET (Land installed marine powered energy transformer) harnesses oscillating water column technology to provide 500kW of power for the national grid under SRO 3.

Visual intrusion is minimised by the low profile of the device and material colours. The reduction / elimination of noise is achieved by use of appropriate materials in the construction of the turbine generators and aerodynamic designs that minimise noise generation.

The company now plans to use the larger resource of the Atlantic Ocean to generate more power with their prototype offshore machine. The £2.7M wave-power machine is expected to be launched next summer. The location has yet to be determined but when operational, the commercial scheme will supply enough electricity to power 1,400 homes.

Energy from Biomass and Wastes

Introduction

125. There is a range of materials that can be converted into energy using a variety of processes and technologies. Energy crops are plant materials grown specifically for use as a fuel, for example short rotation coppicing of willow or poplar. Forestry residues include "brash" (the material from conventional timber extraction and tree thinning which would otherwise be left on the forest floor, and "whole tree comminution" i.e. the mechanical felling and chipping of whole small trees to produce wood fuel chips. Agricultural wastes include straw, chicken litter and farm slurries. Other wastes that can be converted into energy include sewage sludge and municipal solid waste.

126. A general distinction can be made between biomass fuels produced from plant material or animal wastes and waste to energy fuels produced from municipal and industrial wastes. The distinction is not clear cut and can lead to much debate. In particular, as noted in NPPG 6, waste combustion developments may not always be, following an assessment of the Best Practical Environmental Option, the most acceptable means of managing waste under the National Waste Strategy (NWS).

127. It is proposed to include within the Renewables Obligation (Scotland), only energy derived from the biodegradable element of waste, as long as the fuel stream is at least 98% biodegradable. The incineration of municipal waste will thus not be supported. However, in order to support the development of more advanced waste technologies, such as pyrolysis, gasification and anaerobic digestion, the biodegradable fraction of energy from municipal waste using these technologies will qualify for inclusion, as will energy derived from forestry biomass, energy crops and biodegradable agricultural residues by any process.

Biomass Fuels

128. The nature of the particular fuel will determine the way that energy is recovered. Dry combustible fuels, such as those from forestry and agriculture, can be burned (combusted) to produce heat and/or power. Wet wastes, particularly from farm slurries, can be digested to produce a methane-rich biogas, which can then be burned as a fuel.

129. Increasing use is being made of advanced conversion technologies, such as gasification and pyrolysis systems, which offer superior efficiencies compared with combustion for power generation. Gasification is a thermo-chemical process in which biomass is heated in the absence of air, to produce a low-energy gas containing hydrogen, carbon dioxide and methane. The gas can be used as a fuel in a turbine or combustion engine to generate electricity. Fast pyrolysis is a high temperature process in which biomass is rapidly heated in the absence of oxygen. As a result it decomposes to generate mostly vapours and aerosols and some charcoal. After cooling and condensation, a dark brown mobile liquid is formed which has a heating value about half that of conventional fuel oil.

130. For both dry and wet biomass wastes, disposal can often be an issue - for example, poultry litter, straw or slurries. Using the biomass wastes as an energy resource not only provides an environmentally acceptable method of waste disposal thereby assisting traditional agricultural activity, but also gives economic benefits by providing a source of heat or power.

131. Combined heat and power (CHP) is becoming an increasingly attractive option for biomass plant, offering a reliable low-cost heat source for industrial or commercial use (such as a district heating system for a small community), together with electricity that can be sold to the local grid. Forest residues, industrial wood wastes and a range of agricultural wastes are often readily available as fuel for CHP plant. Energy crops, such as willow or poplar coppice are also becoming important.

132. Several biomass fuels, such as energy crops and forestry residues differ from other sources of renewable energy in that they are grown rather than harnessed. They trap carbon dioxide when growing and give it off when burned. However, they are regarded as "CO 2 neutral" as the carbon released on combustion is only that which was absorbed during growth ('contemporary carbon') - the gas is simply recycled. When burned, instead of fossil fuels, a net reduction in carbon emissions is achieved.

Energy Crops

133. Energy crops are important as a renewable energy technology as they can be grown to meet the needs of the market. They may be grown specifically for use as a fuel and can provide long-term secure resources. This sets them apart from other renewable resources that must be harnessed where they occur. They require very little input of herbicides and pesticides, and when established on agricultural land usually result in an increase in bio-diversity.

134. The most advanced energy crop for northern European conditions is coppiced willow, grown on a rotation of 2-4 years, and commonly referred to as Short Rotation Coppice, or SRC. The crop is established by planting up to 18,000 cuttings per hectare. After 1 year these are cut back close to the ground which causes them to form multiple shoots (i.e. to coppice). The crop is then allowed to grow for 2 to 4 years, after which time the fuel is harvested by cutting the stems close to the soil level. The cut stems again form multiple shoots which grow on for a further 2 to 4 years to become the next harvest. This cycle of harvest and re-growth can be repeated many times. The shoots can be harvested as chips, short billets or as whole stems of 25-50mm diameter and 3-4 metres length.

135. For short rotation coppice, the area of land required to support the fuel consumption for each MW of power generation at 20% efficiency would typically be of the order of 630 hectares. This might fall to less than 350 hectares at the higher conversion efficiency available from 'gasification'. Agricultural land which is taken out of food production under the European Community Arable Areas Payments Scheme, and is therefore 'set aside' for at least five years, is considered to have particular potential for short rotation coppice. Opportunities may also exist on derelict land undergoing restoration.

("Establishing Short Rotation Coppice" Forestry Commission Practice Note 7. 1999.)

136. Apart from the visual impact of growing coppice, there may be an impact on the local water table. Growing coppice willow and poplar results in an increase in the number of species of plants and wildlife compared to normal farmland. This effect is enhanced when the planting is close to woodland. Energy crops are tall (up to 7m) compared with normal crops, so some sensitivity should be exercised when designing the planting so as not to obstruct viewpoints. There are a number of Forestry Commission publications on SRC.

Forestry Residues

137. About 12% of the UK's land area is covered with trees, with about 47% of this wooded/forested area located in Scotland. Wood for fuel, in commercial quantities, can be produced as a by-product of forestry/tree management. The residual material from these operations (e.g. branches, treetops) is a clean fuel that can be converted to useful energy. Wood has a relatively low calorific value of around 19GJ/dry tonne. When harvested, wood has moisture content of around 55% by weight.

138. In Scotland there are over 1,318,000 hectares of woodland and forest, almost 17% of the land area of the country. It is estimated that this resource is capable of producing annually, sustainable wood fuel capable of meeting the electricity requirements of perhaps 250,000 homes.

139. Considerable areas of forest are required to support a wood-fired power station. A 6MW station with a plant efficiency of 20%, for example, would consume the material from between 430 and 2,150 hectares a year of sustainably managed forest at harvest. The wide range indicates the extremely variable yield of forest residues, which in turn depends on factors such as terrain and accessibility, tree species and age, and the use to which the timber - as opposed to the residues - will be put. Nevertheless, using forest residues as a source of energy can provide a second crop from a sustainably managed forest. However, the actual exploitation of this resource will also be dependent on other factors such as the conservation status of the woodland, accessibility and countryside policies.

Fig 10 : Estimated annual consumption of a forestry residue fired power station

Source : ETSU

Wood Fuel from Conventional Forestry

Fig 11 : Methods of Harvesting Wood Fuel