1. Service Statement and further advice
Our Service Statement sets out the level of engagement you can expect from us during the planning process. We ask that you allow sufficient time in your project plan to accommodate our advice. Our customer care response deadline is 20 working days, but on some occasions other statutory casework will take priority and cause delays in responding to requests for advice.
You should make initial contact with the NatureScot Area Office relevant to the location of your development. Information on the NatureScot Areas and contact details for our offices. Thereafter you should direct all queries only to the NatureScot case officer assigned to your proposal, who will co-ordinate any advice response.
2. General advice, guidance and information
To help avoid delays caused by incomplete submissions, you should refer to the checklist at Annex 1 of this document. We recommend that you use the list to inform your approach to Environmental Impact Assessment (EIA), and complete the checklist prior to submission of the EIA report. It can be included as part of the EIA report (and at gate-check for section 36 applications) to demonstrate how natural heritage issues have been addressed.
It is your responsibility to identify and assess which activities associated with the construction, operation and decommissioning of your development are likely to have a significant environmental effect on natural heritage receptors (including landscape and visual) based on your own site investigations and the scoping advice you may receive. Where an assessment has been carried out, it is useful for that information to be presented in the EIA report even if the conclusion is that there will not be significant effects. This is to demonstrate that all relevant interests have been adequately considered. However this does not mean that every issue needs to be covered in detail in the EIA report. A table of issues/ interests initially considered but then scoped out of assessment can be provided.
The general pre-application/ scoping advice presented below mainly covers key points for wildlife and habitat topics.
You should also refer to the guidance on landscape and visual impacts found on our website.
An increasingly common issue to consider is turbine lighting. Turbines of 150m or taller require visible aviation lighting - see Civil Aviation Authority guidance. It is also possible that turbines less than 150m tall may require visible lighting depending on location and proximity to both civil and military aviation interests. The applicant should determine whether visible lighting is required and, wherever this is the case, we advise that there is a need for a lighting impact assessment. There may also be a need for an assessment of risks to birds. Please see Annex 2 of this document for our advice on assessing the effects of turbine lighting in relation to landscape and visual, and birds.
2.1 General guidance for assessing impacts on the natural heritage
The results of the surveys and assessment should be used to avoid or minimise impacts, thereby informing the iterative layout and design of the wind farm. You should refer to, but not be limited to, the following sources of NatureScot guidance and information to ensure that you undertake a robust EIA:
- On-shore wind energy. This page also has links to topic specific guidance on birds, landscape etc.
- Planning and development: protected species. This page provides more information on how to take account of protected animals.
Our guidance is reviewed and amended on a regular basis, so please ensure you are following the latest version of the guidance on our website. A complete list of standing advice and guidance is available, which provides easy reference to latest versions of documents. If significant land use, guidance, habitat or population changes have occurred since your survey, advice should be sought from us prior to application submission to ensure the surveys remain adequate. Where proposed survey methods or other work deviates from the published guidance, you should agree this with us in advance of survey work being carried out.
The absence of records for a particular location does not necessarily mean that protected species are not present, so species surveys should not be ruled out solely for this reason. It could just be because that location has not been formally surveyed before. In addition some species have been found in unexpected places, for example remnant freshwater pearl mussel populations above impassable fish obstacles.
The applicant should also consider the need for species licences as part of any development and contact [email protected] regarding any licence application.
2.2 Terrestrial habitats
Habitat surveys should include:
- Phase 1 survey for all terrestrial habitats likely to be affected by the development. This should include an appropriate area beyond the footprint of the development to assess more distant effects and to inform any redesign or micro-siting.
- NVC survey of habitats listed on Annex 1 of the EC Habitats Directive and UKBAP Priority Habitats, accompanied by supporting quadrat information. (JNCC Terrestrial Habitat Classification schemes provides links to the different habitat classifications and a habitats correspondence table.)
- Records of any rare and scarce plant species.
- Where peat is present, peat probing at proposed locations of turbines, tracks and other infrastructure, in line with Scottish Government guidance. The results should be used to inform a peat slide assessment. We recommend early engagement with SEPA with regard to excavated peat reuse and disposal. The Carbon and Peatland map 2016 provides some context to your more detailed peat survey work.
An assessment of impacts of hydrological changes (particularly related to groundwater) on habitats should also be included. Access tracks are the elements that will result in the greatest land take, habitat fragmentation and, potentially hydrological disruption. It is therefore important that the track construction methods are clearly described in the EIA report, along with the rationale for their type and location, and all direct and indirect impacts assessed.
Survey results should be used to inform the design and layout process, so that the development avoids, where possible, fragile and priority habitats and other sensitive areas e.g. blanket bog and peat. Where this is not possible, suitable restoration and/or compensation measures should be presented in the EIA report in the form of a draft Habitat Management Plan (HMP). HMPs should follow our guidance on What to consider and include in Habitat Management Plans.
As a minimum, all areas directly (e.g. watercourse crossings) or indirectly (e.g. sediment run off) affected by the development and appropriate buffers up and downstream should have a habitat survey following the Scottish Fisheries Coordination Centre method referenced below. This should inform the likelihood of the presence of salmonids, eels, freshwater pearl mussel and other protected/ BAP species and so the need or otherwise for species specific surveys. Where there is connectivity to protected areas (e.g. river or loch Special Area of Conservation (SAC)), then a higher level of survey effort and assessment targeted to the interest of the protected area may be needed to inform an assessment of the impacts on the protected area (e.g. an appropriate assessment for a SAC).
Read our guidance on freshwater pearl mussel survey methods. The Scottish Fisheries Coordination Centre (SFCC) provides links to the recommended SFCC habitat survey method (Habitat Surveys Training Course Manual, Revised August 2007), as well as other useful survey method information for fish. Note that where there is suitable habitat for freshwater pearl mussel, and particularly where salmonids are present, we would expect a freshwater pearl mussel survey to be carried out following our guidance.
The exceptions for this would the Borders, Lothian and some parts of Fife where freshwater pearl mussel are unlikely to be present. Advice on the need or otherwise for freshwater pearl mussel surveys should be sought from the NatureScot case officer for developments in Fife.
Where the proposed development site has permanent watercourses or water bodies in it or connected to it, you should seek advice from SEPA regarding water crossings and the adequacy of any hydrological work undertaken as part of the EIA.
2.4 Species which may not require surveys to inform the EIA
There are some species that, with standard mitigation, are unlikely to experience a significant environmental effect during construction/ operation of onshore wind farms (e.g. moths and other invertebrates, reptiles, amphibians, etc.). Such species will not require surveys to inform the EIA. Instead, we advise that you should be able to apply mitigation during construction to avoid committing an offence. You should however provide clear reasoning for scoping out species surveys in this way, either in the scoping report submitted to the planning authority for a scoping opinion, or the EIA report. Please note that this advice is not likely to apply where the potentially affected species are European Protected Species (EPS), or where there could be effects on protected species that are interests/features of protected areas. In both cases, survey is likely to be required to inform the EIA report/ planning submission.
Find out which species are legally protected.
2.5 Access & Recreation
Planning Authorities including National Park Authorities have a duty to uphold access rights within their areas. These authorities have a lead role in advising on access management within the development site, including the effects of the development on existing access and opportunities for improved access provision. We recommend that you engage with Planning Authorities in the preparation of an access management plan. This should identify the current recreational activities in the area and any positive or negative impacts that may occur as a consequence of the development both during construction and operation. We may also wish to be involved where impacts on nationally important recreation interests are identified.
Access should be managed actively during the construction phase, with restrictions kept to the minimum area and duration that is practical and reasonable, and adapted as the site develops to focus on where actual risks are present. This approach is likely to encourage greater compliance by the public and will therefore be more effective in meeting safety needs, including obligations under the Construction (Design & Management) Regulations. Further information about access provision and management can be found in Good Practice during Wind Farm Construction.
2.6 Decommissioning and restoration
The EIA process should consider the implications of decommissioning wind farm sites. Guidance on decommissioning can be found on our website via the first link in section 2a above. The Decommissioning and Restoration Plan (DRP) presented in the EIA report should be brief but provide an appropriate level of detail about how the site infrastructure may be removed and how the site is intended to be restored. The DRP should be revised 3-5 years prior to the year of decommissioning, to provide full details of decommissioning and restoration for approval by the Planning Authority. This is because environmental conditions, laws and techniques may change during the operational lifetime of a scheme. Further survey work may be required to inform the final decommissioning plan. As a guide, the final decommissioning plan should contain a similar level of detail to a Construction and Environmental Management Plan.
Restoration should include the removal of new tracks and restoration of existing tracks to their pre-wind farm width during the decommissioning process, to return the site to the same or better state than pre-construction. However, we recognise that there could be situations where retention of some tracks might be beneficial (e.g. for access and recreation where they provide links to important routes, where removal may cause damage to important natural heritage interests, etc.). The pros and cons of track removal/retention for each individual site can be considered more fully in the 3-5 years prior to a decision being taken on decommissioning. This should be done in consultation with the Planning Authority (and NatureScot and SEPA, as appropriate).
Annex 1 - pre-submission EIA report/environmental report checklist
This is a checklist of NatureScot requirements for what to include in an EIA report (or environmental report accompanying a planning application) - you should also refer to the published NatureScot guidance referred to in section 2a of the general advice document, as well as any development specific pre-application advice provided by NatureScot.
NatureScot scoping and pre-application advice
- Demonstrate that you have taken account of specific NATURESCOT scoping and other pre-application advice. It is useful to provide a table summarising the key points raised at scoping/ during pre-application, alongside information on how you have addressed them.
Figures - general advice ("figures" includes maps, figures, photographs and other visualisations)
- All figures should be clear and of good quality, of an appropriate scale, with distinct legends and scale bar (where appropriate).
- Unless otherwise agreed in writing with NatureScot, the ZTVs and figures used in support of the landscape and visual impact assessment should follow the national standards set out in Visual Representation of Wind Farms (February 2017) guidance.
- All ecological figures should show the application boundary, proposed turbines, tracks and other infrastructure locations, as well as the relevant ecological information/survey results.
Collecting and presenting information - general advice
- We recommend that the ecological chapters are split into topics, e.g. protected areas, species (birds, bats, otter, etc.), habitats (terrestrial, freshwater), etc. Information and assessment of which activities associated with the construction, operation and decommissioning of the development are likely to have direct and indirect (including cumulative) significant environmental effects on the relevant natural heritage receptors, along with clear details of any mitigation, should be presented.
- A table of issues/ interests initially considered but then scoped out of further assessment should be provided in an annex, along with a short justification for each issue/ interest.
- A schedule of environmental mitigation should be provided in an annex for developments with impacts on multiple natural heritage interests. The schedule should compile all the environmental mitigation/ enhancement measures into one list/ table, for ease of reference.
- Sensitive species information should be presented in a confidential annex with restricted circulation. Advice on how to deal with sensitive information.
- In addition to the specific requirements detailed in the sections below, full survey details including raw data, workings for calculations and results should be presented in the EIA Report. Technical appendices should be used for this where appropriate.
- Non-avian species surveys should normally have been completed no more than 18 months prior to submission of the application, to ensure that the survey results are a contemporary reflection of species activity at and around the site. It may be possible to rely on older surveys provided that they are still likely to be representative, but we expect the developer to provide a clear rationale for reliance on such surveys and to discuss this with us in advance.
- Two complete years of bird survey data should have been collected within the last 5 years (unless it can be demonstrated that a shorter period of survey is sufficient and this has been agreed in writing with NatureScot). Advice should also have been sought from NatureScot if some or all of the survey data has been collected more than 3 years ago and local or wider populations of key bird species are known to be changing rapidly. This also applies if there have been significant habitat changes between the survey being carried out and application submission that are likely to affect the level of bird activity in the area (e.g. the baseline has changed say from large area of mature plantation to clear felled open ground).
- Bat surveys should follow the recommended levels of survey effort set out in Bats and onshore wind turbines – survey, assessment and mitigation (January 2019)
- Full survey methodologies need not be presented in the EIA report where they have followed recognised methodologies that are publicly available (e.g. via the NatureScot website). A figure (see point 15 below) along with an outline description including dates, weather conditions (where relevant to the survey type) and how the survey was undertaken, along with a link to the methodology is sufficient. (E.g. “A habitat suitability survey following the Scottish Fisheries Coordination Centre methodology was undertaken on 12 July 2019 along the watercourses shown in figure X. Watercourses A and B were identified as having potential freshwater pearl mussel habitat, so were surveyed for freshwater pearl mussel on 13 July 2019 following methodology. The weather when the surveys were carried out was dry, with little rain in the preceding week. Consequently the water was considered to be at normal level.”)
- Where survey methods or other work deviates from published guidance, deviations should have been agreed in writing with NatureScot in advance of carrying out survey work. A full description of the methodology used should be provided in the EIA report (technical appendices should be used for this where appropriate), along with an explanation of why any deviations are considered appropriate.
- Figures should be used to show the area surveyed/ transects/ quadrat locations etc., for each survey undertaken. (It may be possible to include this information on the results map, where doing so will not obscure the results. For whole development site surveys, it may be appropriate to refer to the boundary shown on the site layout map, rather than provide multiple figures showing the same thing.)
- An outline Decommissioning and Restoration Plan (DRP) should be submitted as part of the EIA report. It should provide an appropriate level of detail about how the site infrastructure is intended to be removed and how the site will be restored.
- If you have confirmed details of all or part the grid connection at the time of EIA report submission, these details should be presented in the EIA report along with assessments of the impacts of the grid connection on the natural heritage (in particular, the nearby protected areas).
Bird survey figures
- A viewshed map should be presented, showing numbered vantage point locations, the 180 degree arc of view/visibility from each vantage point, and areas of overlap. The arc of views should be coloured in such a way that they are distinct from each other, and any overlaps are obvious (without obscuring the underlying topography and site detail).
- Flight maps with labelled or otherwise defined (by colour and/or line type) flight lines, showing the flights banded into below, at and above collision risk height, referenced to a table of flight survey data. Depending on the amount of flight activity, it may be beneficial to present figures by species and/or breeding season (e.g. non-breeding season greylag geese flights on one figure, breeding greylag geese flights on another figure, breeding golden eagle flights on another figure, etc.).
- Nest/ territory locations for target species should be included but comply with the Guidance on Environmental Statements and Annexes of Environmentally Sensitive Bird Information
- All raw bird survey data should be included in an annex and should include the, dates, times and weather conditions of surveys.
Advice for other ecological surveys and presentation of information
- Peat: For sites with peat, a peat probe location, depth and peat slide risk maps should be presented. See section 2b for further information.
- Habitat maps: A habitat/NVC map should be presented, including locations of target notes, overlaid with the site detail as described in point 4 above.
- Species survey figures: Species survey areas/transect, locations of results (e.g. otter couches, pine marten scats, etc.) and target notes, overlaid with the site detail as described in point 4 above.
- Species not surveyed for to inform the EIA/planning submission: The proposed mitigation plan should be provided in the EIA report/ as part of the application submission, where such species are likely to be present on site. See section 2.4 for further information.
- Wild deer: If wild deer are present on or will use the development site, an assessment of the potential impacts on deer welfare, habitats, neighbouring and other interests (e.g. access and recreation, road safety, etc.) should be presented. Where significant impacts may be caused, a draft deer management statement will also be required to address the impacts. We refer you to the advice found in What to consider and include in deer assessments and management at development sites,
- Trees and forestry: If tree felling/woodland clearance will be required as part of the proposed development, we recommend that you contact Forestry and Land Scotland at as early a stage as possible to discuss the Control of Woodland Removal Policy and the implications it may have on the development. You should also refer to the SEPA, NatureScot and FCS joint guidance on how to approach development that will require felling of trees – see the Use of trees cleared to facilitate development on afforested land guidance (April, 2014)
- Recreation and access: The Landscape and Visual Impact Assessment (LVIA) should include consideration of impacts on the landscape setting of the site and the surrounding area and how this may affect the enjoyment of existing outdoor recreational users. Consideration must also be given to the existing and potential use of the area for recreation by the general public, with reference to Scottish access rights under the Land Reform (Scotland) Act 2003 and rights of way.
- Decommissioning: The EIA process should assess the likely impacts of decommissioning. Guidance on decommissioning. The decommissioning and restoration plan presented in the EIA report can be brief. However, it should still provide an appropriate level of detail about how the site infrastructure may be removed and how the site is intended to be restored.
Format of the EIA report and where to send it
- For ease of use, text chapters and appendices of EIA reports should be presented on A4 paper (rather than A3).
- Landscape figures to be provided in a ring binder (rather than being spiral or otherwise bound), for ease of use during site visits.
- Unless otherwise advised by NatureScot, a full hard copy of the entire EIA report (including confidential annexes), plus a copy of the same on cd with file sizes of <10MB per pdf, should be sent direct to the case officer. Electronic file names should clearly indicate their content (e.g. “LVIA Figure 6.18a - VP8 Bonar Bridge”). (Where a NATURESCOT case officer has not been assigned or is unknown, you should contact the relevant Area office to where their development is located, to ask who and where to send the EIA report. Contact details for Areas and offices.
Annex 2 - NatureScot advice on the scope of assessment for turbine lighting
Turbines of 150m or taller will require visible lighting - see Civil Aviation Authority (CAA) guidance. It is also possible that turbines less than 150m tall may require visible lighting depending on location and proximity to both civil and military aviation interests.
The requirement for aviation lighting of onshore turbines is a fairly recent issue for the wind energy sector and we have relatively limited experience of assessing the effects and understanding the impacts. Nonetheless, we consider that the landscape and visual effects of aviation lighting could be significant in some locations (see Siting and Designing wind farms in the landscape for further discussion). We also note than in some countries, such as Germany, efforts are now being made to reduce the number of aviation lights on wind turbines due to concerns about cumulative effects.
Wind farms in Scotland tend to be located in areas which contain limited artificial lighting. Darkness/ dark skies in these areas can be valued by people, a proportion of whom may be actively seeking out and enjoying good natural views of the night sky. Turbine lights can be seen over considerable distances, with some clearly visible at greater than 20-30km. CAA onshore turbine lighting requirements are for ‘steady’ lighting, but an asynchronous flashing effect can also occur, depending on wind direction relative to the viewer, as turbine blades pass in front of the nacelle-mounted lighting.
In many circumstances the lights will be seen unusually high up in the view compared with the typical experience of artificial lights being situated in more lowland areas or along valley floors. Turbine lighting will not cause sky glow, but can contribute towards an absence of natural darkness. It may be distracting or perceived as incongruous when seen as bright red points with no structural or spatial reference. It may adversely affect some people’s experience and enjoyment of places in darkness and of sunset and sunrise views (noting that turbine lights are switched on before dusk and off after dawn).
There may also be risks to birds, but these are difficult to quantify at this stage. The sections below offer our current advice on how to assess the effects on both landscape and visual and birds. Our understanding is evolving rapidly and this advice is likely to be updated regularly.
Scope of landscape and visual assessment
We recommend that the landscape and visual effects of turbine lighting should be carefully considered and that mitigation options are employed wherever possible.
Assessment of the landscape and visual effects of turbine lighting is a relatively new practice. As a starting point we highlight advice on turbine lighting in our existing landscape guidance1. However our advice is evolving and we recommend that the assessment should include:
1 Please note that some brief advice is contained at paras 2.11-2.13 of our Siting and Design guidance and at paras 174-177 of our Visual Representation guidance
- Clear information on the positions and intensity of lighting proposed. If only certain turbines are to be lit (e.g. due to a mix of turbine heights) a plan should show which are the lit turbines (all turbines in the plan should be numbered).
- A ZTV map which shows the areas from which the nacelle and tower lights may be seen.
- A table which lists how many lit turbines will be visible from each viewpoint – see the example below.
|-||VP1 Hillside (2.6km)||VP2 Lochview (12.3km)||VP3 Glenburn (6.7km)||etc||etc||etc||etc|
Xx - Lights visible as pair on nacelle and tower
X - Light visible as single light on nacelle
X -VP3 - Lights currently screened by forestry
- Annotation of the positions of turbine lighting (including intermediate tower lights) on all wirelines from every viewpoint.
- Assessment based on fieldwork for all viewpoints with potential visibility of lighting, and where effects may be significant. In a worst case scenario this may involve all viewpoints but professional judgement should be applied to ensure the assessment remains focused on likely significant effects (in accordance with GLVIA).
- Assessment of effects on landscape character, in particular where qualities of wildness, remoteness and lack of man-made elements is a feature of that landscape.
- Night-time visualisations from a limited / proportionate number of representative viewpoints (we suggest two or three). These may be selected on the basis of sensitivity or regular usage during low-light conditions. It is difficult to illustrate turbine lighting well in visualisations, and this is discussed further in our Visual representation of wind farms guidance. We welcome the recent efforts of developers and consultants to move this issue forwards.
Additionally, we advise that:
- Turbine lighting would be an integral part of the wind turbine and will contribute to the magnitude of change introduced. As such the assessment of the effects of lighting should be considered throughout the LVIA rather than produced as a separate section within the chapter. This will allow for a fully informed assessment of the impacts of the wind turbines (both day and night, individual and cumulative) on landscape character and visual amenity. A separate summary of the effects of aviation lights should be included for ease of reference.
- The assessment should take into account the baseline darkness/ artificial lighting characteristics and people’s likely use of different areas during darkness and low light (dusk/ dawn) conditions.
- The extent of the lighting assessment study area for LVIA should be informed by the Zone of Theoretical Visibility (ZTV) map and an understanding of the nature of the likely effects.
- In some cases, there may be the need to select some of the LVIA assessment viewpoints on the basis of the turbine lighting impacts, as opposed to day-time visual effects. Edge of settlement locations are likely to be better lighting assessment viewpoints, compared with locations within towns/ villages (i.e. given the influence of existing street lighting, etc.).
- The scope and content of the assessment should be agreed early on with the relevant determining authority. Samples of baseline photography can be useful to inform this stage.
Finally, we encourage applicants to explore all available forms of lighting mitigation as a means of reducing or avoiding impacts. A range of mitigation options are available and these should be considered on a case by case basis and discussed with the CAA as these are evolving rapidly. Table 1 below summarises the options we currently understand to be available.
Scope of assessment for impacts on birds
We know from more extensive studies at communication towers and other structures that lighting can, in some circumstances, result in significant collision mortality, though the impact of these mortality events on species populations is not well understood. The effect of lighting on birds at turbines, communication towers and other structures is discussed in more detail in this information note. Wind farms are often sited in open country well away from other sources of lighting, so may be particularly visible to birds in some conditions.
Evidence from published studies suggests that lights may be particularly problematic for nocturnally migrating passerines (especially in periods of poor weather such as heavy rain, fog and low cloud), as well as some burrow nesting seabirds (especially petrels, shearwaters and Atlantic puffin). Collisions with some structures (such as communication towers) can lead to mass kills of some bird species, though the impact of these mortality events on species populations is not well understood.
Onshore wind farms may also require erection of meteorology masts, which may be guyed and also require lighting. These present an additional hazard to birds - see guidance.
An assessment of the possible effects of lighting on birds may be required in the following situations:
- Wind turbines on or adjacent to a seabird colony that hosts the burrow nesting species, Manx shearwater, European storm petrel, Leach’s storm petrel and Atlantic puffin;
- Wind turbines that are on or adjacent to protected areas that host large concentrations of wintering waterbirds, where such sites are located within open country away from other sources of artificial light; and
- Where wind farms are located on migratory corridors or bottlenecks for nocturnally migrating passerines.
The sensitivity to birds arising from any lighting required will depend on the species likely to be affected as well as the extent of lighting required. Relevant issues to consider will include the nature of the lights (number and position on turbines); the number of turbines that will be lit; how long they will be lit for and their location within the wind farm turbine cluster. The assessment should consider the number of birds likely to be present on or near the wind farm that may be affected by the lights.
There is no detailed methodology available to assess and quantify these risks. If the desk study suggests that high numbers of sensitive species are likely to be present when the lights are switched on, we recommend that the mitigation measures below are explored (in tandem with the landscape and visual assessment) to reduce these risks. In particularly sensitive locations, there may be benefit in exploring alternative lighting options, such as flashing lights, or different colours of lights – but these would require careful assessment and agreement with the CAA.
Published: October 2020
Table 1: Mitigation options for aviation lighting
This is our current understanding which is evolving quickly. Our views on the effectiveness of these are informed by the assessments we have reviewed during 2019/20 – but we have limited evidence on which to base these views, and very few built schemes to examine. We are keeping this under review. The options shaded green are embedded in existing CAA guidance. Those shaded red require agreement with the CAA on a case by case basis.
|Mitigation option||How it works?||How effective is this mitigation?|
|Directional intensity / shielding of lights||
Already set out in ICAO requirements and EASA CS-ADR-DSN Chapter Q. This focusses the 2000 cd lighting in the horizontal plane (+ or – a few degrees) and reduces the intensity of the light from above and below.
Both regulations stipulate minimum requirements as well as additional recommended vertical angles, which cannot be ignored without justification. Most lights on the market will incorporate this as standard.
This helps reduce the intensity of the lights from very low, or very high viewpoints near the turbines, but at distances of between around 2 and 10km the full 2000 candela light intensity may still be visible as the brightest ‘beam’ from the light spreads out, depending on the height of the nacelle, the relative height of the viewer and the design of the light.
This form of mitigation is less likely to benefit bird species that fly at intermediate (i.e. turbine) heights. It may benefit those species which fly very close the ground (less likely at risk of collision anyway) or at altitude.
This mitigation measure may have limited effect on reducing impacts on birds and landscape, depending on location.
|Reduce intensity of lights from 2000 to 200 cd||Already set out in CAA guidance CAP 764. Lights can be dimmed to 200 cd in good visibility (greater than 5km). We note that 200 cd lights can still be visible at greater than 20km in good visibility conditions (based on fieldwork undertaken in 2018 and 2019).||
This helps reduce the intensity of the lights, but they are still visible at considerable distances (20km plus).
This may reduce the effects on some species of birds, but the benefits are hard to quantify.
This mitigation measure may have limited effect on reducing the impacts on birds and landscape, depending on location.
|Selected turbine lighting or no turbine lighting||It may be acceptable to only light certain turbines (as agreed at Viking for example), or none of the turbines, on the basis of an aeronautical study (as provided for in ICAO Annex 14), subject to CAA approval on a case by case basis.||
Reducing the number of lights may help reduce effects. In some locations however, even 3 – 4 lights may appear incongruous. Birds could still be
Effectiveness is site specific and requires assessment.
If no lights are proposed – the effects will be zero and this is very effective mitigation. However small numbers of lights could still result in significant effects in some locations.
|Radar activated lighting||
CAA support this in principle and are considering the parameters in detail. In the meantime CAA are happy to discuss the approach on a case by case basis. In use in other countries, to differing extents, but it is acknowledged that the costs for primary radar are high. The lights would be switched off until the radar detects an aircraft within a defined envelope of airspace (we understand this to be 300m above the turbines and 4km horizontal distance).
Two forms of radar solution are currently available:
Primary radar: requires a radar system to be installed on a tower, or towers, on the windfarm. This requires additional infrastructure (which requires planning permission) – and the costs are high. This system emits a radar signal, which bounces off an object back to the radar. This system can be triggered by large flocks of birds, or even passing rain showers – so may result in frequent false activation.
Secondary radar: This is a ‘listening’ radar which listens for a signal from a transponder in an aircraft. The receivers are small (similar to a TV aerial) and can be attached to wind turbine towers. No further infrastructure is required. The cost of this system is much lower than primary. Lights only switched on for around 2 – 4 minutes as the aircraft passes over. Only triggered by a transponder – so less likely to have false activations. This system requires a small change to aviation legislation to require all aircraft that fly at night to carry a transponder (currently due by 2024, though industry working to have this brought forward).
Both radar systems could potentially be shared between wind farms, helping to reduce costs.
We support the use of secondary radar because:
1) It is likely to result in fewer activations and the lights would be on for less time
2) It involves less infrastructure (and therefore lower risks to birds and landscape / visual effects)
3) It is cheaper than primary radar.
In most locations this form of mitigation should be very effective – but we need detailed information on the number of times the lights could be switched on and the duration for which this would occur.
Potentially very effective, depending on frequency and duration.
Primary radar remains an option but is less attractive for the reasons set out opposite.
|Infra red (IR) only lighting||All wind farms have IR lighting as standard. In some locations it may be possible to agree to having only IR lights in place (ie no red lights) but this would need to be agreed with CAA. IR lights are visible to those pilots using night vision equipment (eg MoD, Police, SAR etc)||A very effective form of mitigation. Removes all visual effects and effects on birds. More effective than radar as the lights would never be seen.|
|Micro siting and turbine height||The need for lights can also be avoided through the use of smaller turbines (less than 150m) and the visual impacts can potentially be designed out through careful micrositing.||Potentially very effective if the need for lights can be avoided. No lights – no effects.|