For applied ecology to have real-world impact, collaboration between scientists, policy makers and industry is crucial. To demonstrate this, we present a case study of the planning process for micro-wind turbines (units generating <50 kW) in the UK. Micro-turbines are now routinely installed in many European countries and the USA, and in spite of the rapid growth in numbers, there has been little study of their impact on wildlife. Consequently, the evidence-base upon which to establish planning guidance is very limited.
Using the situation in the UK as an example, we show that (i) the planning process for micro-turbines varies widely among local authorities; (ii) a lack of data on their effects on wildlife makes interpretation of ecological surveys problematic; and (iii) recent changes to the planning process, designed to permit installation of micro-turbines in some contexts without requiring planning permission, are unlikely to change this status quo.
Synthesis and applications. We argue that (i) further research on the effects of micro-turbines on wildlife should take into account the needs of stakeholders, in particular, with regard to how effects may vary in different contexts; (ii) better planning guidance should be developed urgently, incorporating all available evidence and identifying further research needs; and (iii) a working group including representatives from the turbine industry, ecologists, policy makers and statutory bodies should be set up to streamline this process. These recommendations provide a starting point for on-the-ground turbine installers, planners and ecologists, and a way forward for managing the future planning process for micro-turbines.
In the face of rapidly growing anthropogenic pressures on the environment, it is becoming increasingly clear that for ecological science to be effectively applied, collaboration between scientists, policy makers and industry is crucial (Hill & Arnold 2012; Milner-Gulland et al. 2012). This is especially clear where conflicts occur between environmental and economic considerations, for example, in the development and promotion of renewable energy sources such as wind energy.
Much of the focus in the wind energy sector to date has been on wind farms containing multiple large turbines with rotor diameters up to 100 m, each generating up to 2·3 MW. Fatalities and disturbance effects of wind farms have been documented for a wide variety of bird and bat species and include collision mortality (e.g. Drewitt & Langston 2006; Kunz et al. 2007), disturbance or displacement effects, resulting in lower breeding bird densities (Pearce-Higgins et al. 2009), lower numbers of foraging birds (Larsen & Madsen 2000) or reduced flight activity (Desholm & Kahlert 2005). However, effects can be highly variable between sites, with few observable effects at many farms but high impacts at others; this is likely due to differences in, for example, site topography, habitat, wind farm design and species present (Drewitt & Langston 2006).
A relatively recent development is the expansion of the micro-wind sector. In the UK, micro-generation of electricity is defined as units generating up to 50 kW (Energy Act 2004; http://www.legislation.gov.uk/ukpga/2004/20/pdfs/ukpga_20040020_en.pdf). In the case of micro-wind, this normally constitutes free-standing or building-mounted turbines that are usually installed singly, with rotor diameters between 1 m and 11 m and up to 30 m hub height, although, for example, the majority of units installed in the UK are free-standing turbines that range from 6 to 12 m hub height (RenewableUK 2011). Rapid technological advances have made micro-turbines increasingly affordable to private individuals, and many governments worldwide now provide installation incentives in the form of tax breaks or feed-in tariffs in the case of grid-connected units. As a consequence, the number of micro-turbines has grown rapidly over the past decade, with just over 20 000 now installed in the UK (RenewableUK 2011), and approximately 100 000 sold in the USA since 1980 (American Wind Energy Association 2010). Worldwide, the total number of units installed exceeds 650 000 although this includes turbines of 50–100 kW capacity as there is currently no agreed definition of ‘micro’ or ‘small’ turbine (World Wind Energy Association 2012).
Large wind farm developments are generally sited in relatively remote and open areas, whereas micro-turbines are installed in a wide range of rural and suburban locations in gardens and adjacent farmland, often in relatively close proximity to dwellings or settlements (J. Minderman, C. J. Pendlebury, J. W. Pearce-Higgins & K. J. Park, unpublished data). Although there are anecdotal reports of bird and bat mortality at micro-turbine sites (Bat Conservation Trust 2010), until very recently, no published data on the effects of micro-turbines on wildlife existed. Thus, the evidence upon which to base any siting recommendations is limited. Recent research found that whilst bird flight activity is the same at different distance bands from the turbine, bat activity is reduced in the immediate vicinity of, but not at longer distances (20–25 m) from, operating micro-turbines (Minderman et al. 2012). While this suggests that micro-turbines can adversely affect habitat use by bats, the mechanism for this observed effect and the scale at which it operates in different habitats remain unclear. Avoidance of turbines may have positive benefits through reduced mortality via collisions and, in many cases, any reductions in habitat use on a local level may have limited wider consequences. However, in landscapes with few suitable habitats to begin with, such disturbance may reduce the perceived quality of the remaining habitat, disrupt commuting routes between foraging patches, and possibly exert population-level effects. Moreover, as all bats are listed as European protected species of animals in the European Union's Council Directive 92/43/EEC (the Habitats Directive), there is a legislative need to characterize situations in which mortality or disturbance is likely to occur.
Although in the UK, formal Environmental Impact Assessments are normally not required for micro-turbine installations (i.e. for single-turbine developments with hub heights <15 m, WWF-UK 2001), until recently, all permanent installations of micro-turbines in the UK required planning permission. The planning process is seen by many in the turbine industry as a barrier to the expansion of the micro-renewables sector, with consequent impacts on market growth, loss of position in the global turbine manufacturing industry and a reduction in the potential contribution to the renewable energy target (e.g. British Wind Energy Association 2010). In part to address this issue, Permitted Development Rights (PDR), which came into effect in Scotland on 10 March 2010 (http://www.legislation.gov.uk/ssi/2010/27/pdfs/ssi_20100027_en.pdf) and in England on 1 December 2011 (http://www.legislation.gov.uk/uksi/2011/2056/made), allow the installation of micro-turbines without the need for planning permission, provided certain criteria are met.
Here, we intend to draw attention to the immediate need for improved dialogue and collaboration between applied ecologists, policy makers and industry, using wildlife conservation and the planning process for micro-turbines in the UK as a case study. We do this by (i) examining the planning process as it relates to micro-turbines and wildlife conservation and (ii) assessing the likely implications of PDR in England and Scotland for micro-turbine uptake and its consequences for wildlife conservation. On the basis of this analysis, we suggest a ‘road map’ of next steps needed to both improve the evidence base for the impacts of micro-turbines on wildlife and develop improved planning guidelines for micro-turbines.
The planning process for micro-turbines
A survey designed to gauge attitudes to planning applications for micro-turbines, and which criteria might influence the decision-making process, was sent to local authorities in the UK (Appendix S1, Supporting information). From an effective sample size of 409, 90 (22%) surveys were returned completed (N = 66, N = 18 and N = 6 from England, Scotland, and Wales, respectively, Fig. 1a). The number of planning applications for micro-turbines that local authorities received was highly variable; between April 2009 and 2010, 27% of responding local authorities had received none, 45% had received fewer than five, 19% between five and ten and 10% had received more than 10. Of those that had received applications, 95% were dealt with within 6 months and 5% took between six and twelve months. Of local authorities that had received more than five applications (N = 22), seven had not rejected any, twelve rejected fewer than 25% and three rejected more than 25% of applications.
Visual and landscape impacts were cited far more commonly than any other reason for applications being rejected, followed by concerns over noise (Table 1). Consistent with this, on a scale of 1 (insignificant) to 5 (highly significant), visual amenity was rated the most significant criterion to consider in the decision-making process, followed by noise pollution (Fig. 2). The median score for wildlife (4, ‘quite significant’) was significantly lower than that for visual amenity (Mann–Whitney W =2591, P =0·001).
Table 1. Response to an open question [Appendix S1, question 4, (Supporting information)], asking for the three primary reasons for rejecting turbine planning applications. Included in this table are reasons given by respondents who had not yet received, or rejected any applications but who gave reasons for which they would reject turbine applications in the future. ‘Visual/landscape impact’ includes reasons such as ‘residential amenity’, impacts on built environment/listed buildings, impacts on Areas of Outstanding Beauty, National Scenic areas and Conservation Areas
Reason for rejection
Number (%) of respondents (n = 45)
Wildlife/other environmental impacts
Insufficient detail about potential impacts
Of 73 respondents who expressed an opinion on whether the current guidance they have for assessing micro-turbines was satisfactory, 64% said yes and 36% no. Several respondents stated that guidance at a national level was lacking, for example, ‘National guidance is vague and centred around large wind turbine applications, with nothing specific for small wind turbines’. In particular, several respondents expressed a desire to see more specific guidance and information on wildlife impacts and suitable mitigation (e.g. siting), the assessment of landscape and cumulative impacts, noise generation and impacts.
We asked respondents under what circumstances they would request an ecological survey outside of designated protected areas as part of the decision-making process (Table 2). The most common reason cited was if bats or other protected species are known (or likely) to be present at or near the proposed site, usually based on the assumption that bats are more likely to be present at or near certain habitat features. Several respondents routinely take advice from the council ecologists and statutory agencies [e.g. Scottish Natural Heritage (SNH)] on when surveys would be desirable. In contrast to this, one Scottish local authority stated that, ‘If it [the proposed turbine] was not in a Special Protected Area, Ramsar site etc. then we cannot ask for one’, which appears to be a misinterpretation of SNH policy that only micro-turbines in designated sites should be referred to them. Three respondents stated that they would never request an ecological survey. Of 77 respondents who answered the question regarding the importance of ecological surveys, 51% said that an ecological survey on its own would carry sufficient weight to reject a planning application, 5% saying it would not and 42% said it sometimes would but depended on individual circumstances. Attitudes towards PDR amongst planners were mixed. Whilst some stated that basing permitted development on sizes and particular locations could work, and perhaps even be extended to commercial ventures, others felt it made the system even more complicated, for example, ‘They either ought all to be PD or not. This current two stage process is complex and confusing’. From a practical perspective, however, this comment is pertinent ‘In this past year I don't believe that any of the [micro-turbines] applied for would have met the indicated criteria for permitted development for [micro-turbines]’.
Table 2. Response to an open question [Appendix S1, question 15 (Supporting information)], asking for the circumstances in which an ecological survey would be requested as part of the decision-making process for micro-turbine planning applications. Included in this table are reasons given by respondents who had not yet received any applications but who gave reasons for which they would request ecological surveys in the future
Reason for survey
Number (%) of respondents (n = 68)
If advised by Statutory Agencies, Biodiversity Officer, Council Ecologist etc.
If bats/birds/protected species known or likely to be present
In or near particular habitats, adjacent to hedges/trees
Near/adjacent to designated site
Local nature interests
In rural areas
Following criteria in EIA 1999 regulations
Assessment of Permitted Development Rights
In both Scotland and England, the new PDR legislation concerns only domestic turbines, not those used for commercial purposes, but the way in which PDR have been implemented differs markedly. In Scotland, an application to the local authority is still required for every turbine installed; however, it does not constitute a full planning application, has reduced associated costs, and restricts the local authority to decisions based only on size, design and (if they choose) siting and external appearance. It is applicable only to free-standing turbines and the only siting criterion is that the turbine should be more than 100 m from the curtilage of another dwelling. In England, PDR apply to both building-mounted and free-standing turbines and each has criteria relating to the size and various distance measures (see Table 3 for a summary).
Table 3. The percentage of turbines meeting a selection of the specified criteria for Permitted Development Rights (England). Not all respondents answered all questions, and the total number of respondents is given in brackets for each criteria. There are additional requirements regarding the distance of turbines from curtilage boundary, but we do not have data with which to assess these
% Meeting criteria (total respondents)
The area through which the rotor blades of a turbine spin. An area of 3·8 m2 is approximately equivalent to a rotor diameter of 2·2 m.
Distance from ground to lowest part of the blade to be <5·0 m
A total of 705 planning applications for micro-turbines in England (N = 357), Scotland (N = 250) and Wales (N = 98) were collated. The earliest submission was from 1985 but 81% were submitted between 2006 and 2010. Of these, 75% had been approved, 12% refused, 6% pending and 6% withdrawn (the outcome of the remaining 1% was not clear). A survey requesting information on turbine specifications was sent out by post (Appendix S2, Supporting information): from an effective sample size of 490, 253 (52%) were returned completed. A further 16 surveys were completed unprompted and sent online, giving a total sample of 269 current or planned turbines (Fig. 1b).
Using data from turbine owner surveys, we assessed the proportion of turbines that would have been allowed under PDR, based on size characteristics. The minimum ground-blade distance of 5 m was met by most turbines. However, whilst the vast majority of building-mounted turbines fell within specifications for swept area and height, only a small proportion of the free-standing turbines did (Table 3).
Of the respondents who provided information about the location of the turbine (N = 112), the majority were situated on farmland (56%), followed by rural gardens (20%), suburban/urban gardens (10%), moorland (6%), industrial sites (5%) and school grounds (3%). Only the turbines in gardens are likely to be classed as domestic turbines and therefore within the remit of PDR.
We have provided an overview of the planning process for micro-turbines and how wildlife considerations are taken into account using the current situation in the UK as an example; a clear case of where thorough integration of applied ecology and policy is vital.
The percentage of rejected turbine applications was low (12%). By far the most common reason for rejection was visual intrusion (80% of planning officials), followed by noise pollution (33%) and potential wildlife impacts (18%).
Two-thirds of local authority planners felt that, in general, current guidance for micro-turbines was satisfactory, although wildlife impacts, mitigation and Green Belt issues were raised as in need of further guidance. Guidance and implementation varies considerably across the UK. For example, Suffolk County Council requires detailed bat surveys if the proposed turbine (>5 kW) is within 50 m of habitats likely to be used by bats (Suffolk Biodiversity Planning Support Group 2011), but many other authorities have no such stipulation. At a national scale, a recent joint statement from the UK Statutory Nature Conservation Organizations advised that detailed guidance would not be available until there was a better understanding of the potential adverse impacts (Scottish Natural Heritage 2012). In England, the recently published National Planning Policy Framework [NPFF, Department for Communities & Local Government (2012)] has now revoked a large number of policy guidance and statements. It remains unclear whether the presumption in favour of sustainable development and the promotion of renewable technology will override the requirements that some local authorities have for detailed ecological assessment of micro-turbine proposals.
We found considerable variation in how likely planning officers are to request ecological surveys pre-construction. A small number always ask for ecological surveys whilst others never do; more commonly these are requested if certain species are known to be present (e.g. bats) or in certain habitats. We also have anecdotal evidence of some local authorities asking applicants to demonstrate that their turbine will not impact detrimentally on the local bat population; it is hard to imagine the circumstances under which this could be achieved by private individuals.
Whilst there were some concerns amongst planners on the introduction of PDR for micro-turbines, we show that PDR as it operates in England will not apply to the vast majority of applications for small wind turbines. Only a third of turbines from our sample count as ‘domestic’, and the current qualifying criteria (in particular, total height and swept area) exclude the majority of free-standing units, which are expected to make up the predominant share of existing installations for the foreseeable future (RenewableUK 2011). In Scotland, PDR operates quite differently, although it is too early to say what the impacts will be on micro-turbine uptake. These data suggest that the introduction of such PDR may not make any material difference to the speed or efficiency of the planning process for micro-turbines. Thus, notwithstanding further policy changes (e.g. as introduced by the NPFF in England), it is likely that ecological surveys will continue to be requested for many micro-turbine proposals, even outside formally protected areas. This raises two issues. First, the practical and financial feasibility of comprehensive ecological surveys is likely to deter many potential turbine owners. Second, the current lack of scientific evidence of the effects of micro-turbines on wildlife means that interpretation of survey results will, in any case, be difficult until further studies are published.
Whilst we would argue that studies of the effects of micro-turbines on wildlife are urgently needed, it is clear that much can be learned from previous experiences with larger wind farm developments. For example, survey techniques used at wind farms (e.g. vantage point watches and automated bat detector stations) can be adapted to suit the smaller observational scales needed for micro-turbines (see e.g. Minderman et al. 2012). Wind farm studies now often compare bird- and bat abundances before and after construction, but such BACI designs (Before–After Control-Impact) are yet to be applied to micro-turbines. Moreover, micro-turbines provide interesting opportunities to address issues encountered in studies of larger wind farms. Firstly, wildlife effects can vary substantially between and even within windfarm sites, and this effect is likely to be due to subtle differences in habitat (Drewitt & Langston 2006). Micro-turbines are installed in a much wider range of habitats, and small variations in siting (i.e. distance to habitat features) could have major consequences for likely wildlife impacts (Minderman et al. 2012); therefore, there is much scope for such questions to be addressed in future micro-turbine studies. Secondly, cumulative effects are expected to be important in wind farm developments (Masden et al. 2010) but not often studied. Again, because (i) planning- and construction time-scales are shorter and (ii) they are installed in a wide variety of set ups (e.g. singly, in pairs, in clusters of several), micro-turbines provide excellent opportunities to study the mechanisms of possible cumulative effects.
In summary, we found that the planning process and perspectives of Local Planning Authorities vary widely throughout the UK with little strategic thinking on the impacts on wildlife at a national level, although there are some exceptions (e.g. SNH Sharing Good Practice Workshops; small scale wind and micro-renewables, Perth May 2010). This problematic situation regarding micro-turbines in the UK is a fair reflection of the state of play worldwide: the planning process varies substantially between, and even within, countries. For example, planning requirements vary between Bundesländer (federal states) in Germany and between states in the United States. While requirements are generally more consistent in smaller countries like the Netherlands, guidelines for micro-turbines are entirely based on wind farms. Communications with ecologists, government agencies, consultants and micro-turbine manufacturers and installers during the course of this research has highlighted that concerns about the lack of information (e.g. data on the distribution of turbines and wildlife impacts) and the consequent absence of evidence-based guidance for siting are universal. To fill these knowledge gaps, we call for an improved and more extensive dialogue between ecologists, policy makers, planners and the turbine industry. Specifically, we make the following recommendations:
Further research needs to establish how effects of micro-turbines on wildlife vary in different habitat and landscape contexts (e.g. distances to important habitat features; Minderman et al. 2012) so that adverse impacts may be mitigated against by improved siting decisions. Other outstanding questions include (i) whether turbine size and design (e.g. horizontal vs. vertical axis turbines) modulate impacts, and (ii) to what extent adverse effects on a local level translate into population- or landscape-level effects. Understanding such landscape-level effects requires detailed knowledge of turbine distribution, and given the current dearth of such information, we suggest that a centrally accessible database of micro-turbines is developed, as exists for wind farms in many countries (e.g. UK Wind Energy Database).
Guidance on siting micro-turbines to minimize any potential adverse effects on wildlife should be developed as a matter of urgency. Such guidance should include, among other things, the following: (i) a consensus on what constitutes ‘adverse effects’; (ii) recommendations on which habitats or settings to avoid to minimize risk and/or (iii) ‘safe’ distances from valuable habitat features to minimize adverse effects. While we feel that a combination of recently published data and the precautionary principle should allow the immediate development of initial guidance, it is vital that guidance is updated periodically to incorporate new information as it becomes available.
Further research and the development of siting guidance should occur in parallel and draw on expertise from all stakeholders. We therefore suggest that a working group including members of the scientific community, policy makers, statutory agencies and the turbine industry is convened to integrate this process. This working group should collate evidence, develop guidelines and also identify points where evidence is lacking. Only such an interdisciplinary approach to both the planning- and ecological issues surrounding micro-turbines will ensure effective future development of this renewable energy technology while minimizing any adverse effects on wildlife.
We thank all the local authority planning officials and micro-turbine owners who were involved in pilot-testing and completing surveys, in particular, Scottish Borders Council, Stirling Council, Northumberland Council. Many thanks to Adam Fitche (Environ), Jay Dawson (Stirling Council), Kenny Taylor (Scottish Natural Heritage), Colin Galbraith (Chair; the Scottish Windfarm Bird Steering Group), Tony Fox, Chris Elphick, Elizabeth Masden and one anonymous reviewer for constructive comments on previous versions of this manuscript. Thanks also to information provided by many people throughout this project, and to Mary Marston (Windcrop) for discussions on developing guidance. Christina Campbell helped collect turbine owner survey data. This project was funded by a Leverhulme Research Grant no. F/00 241/L to KJP.