Siting Issues
Karin Sinclair, National Renewable Energy Laboratory
Although energy produced from commercial wind farms in the United States is generally viewed as environmentally benign, environmental and other siting issues can be raised during the permitting process. In many cases, issues brought forth during the permitting process for wind turbines can be similar to issues raised for permitting other development projects; in other cases, the issues are unique to the wind technology. The successful development of a wind project is typically the result of balancing the project’s economic viability and overcoming any siting issues. If a project will cost too much as a result of environmental or community issues, the developer will probably terminate pursuit of the wind project—as would be the case with any other type of development project. The Siting Subcommittee of the National Wind Coordinating Committee (NWCC) developed a guidebook to siting issues (Permitting of Wind Energy Facilities: A Handbook, see References). The document includes an overview of the permitting process, the typical steps required in siting a wind development, and a detailed discussion on specific topics, including land use, noise, birds and other biological resources, visual resources, soil erosion and water quality, public health and safety, cultural and paleontological resources, solid and hazardous wastes, and air quality and climate. The document also includes a number of case studies. The importance of any of the issues covered in the document will vary by site. In some areas, none of these topics will be considered an issue. In others, one or more may be so important that the project could be difficult to permit. Therefore, each site must be evaluated on its own merits. Early assessment on the part of the developer is critical to determining how many and which of these topics could be issues that need to be addressed.
Noise Impacts Much of the noise generated by wind facilities is masked by ambient or background noise of the wind itself. Individuals living in close proximity to a wind turbine may be impacted by noise from the turbine. Consideration of adjacent land uses should be taken into account when evaluating potential development sites.
Visual Impacts It is difficult to quantify the visual impacts of a wind farm because this is such a subjective issue. Computer modeling tools can be used to simulate how a landscape will look with wind turbines. Views can be developed from multiple vantage points. Existing natural and cultural features will also influence the interpretation of the extent of the visual compatibility of wind turbines. Public perception plays a large role in determining visual acceptability of wind turbines. The size of the turbines, number of turbines, and wind farm design (spacing of turbines and physical arrangement of the turbines on the landscape) influence visual impacts. Federal Aviation Administration regulations may require the installation of lights on the turbines, potentially adding to the visual impacts.
Avian Issues Of the three environmental topics (noise, visual, and biological), concerns about the impacts of commercial wind farms on biological/bird and bat populations are frequently raised. Two primary areas of concern are (1) possible litigation resulting from the killing of even one bird if it is protected by the Migratory Bird Treaty Act (MTBA), the Endangered Species Act (ESA), or both; and (2) the effect of avian mortality on bird populations. To properly address these concerns, the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) supported scientifically based avian/wind power interaction research from 1992–2002. In 1999, NWCC’s Avian Subcommittee published Studying Wind Energy/Bird Interactions: A Guidance Document, which summarizes metrics and methodologies for determining or monitoring potential impacts on birds or bats at existing and proposed wind energy sites. The level of rigor required for the evaluation of a proposed site will vary depending on the complexity of and the issues at that site. In some cases, site evaluation can be accomplished by gathering existing information on vegetation, habitat, and wildlife/habitat relationships and conducting a reconnaissance study. This existing information may be adequate to determine whether a site is suitable for a wind development and sufficient to meet the regulatory requirements. Additional on-site information gathered through the use of on-site surveys and monitoring might be required. Information required to adequately assess the site may include bird utilization and abundance, seasonal variations of site usage, species of special concern, breeding birds, and migrating birds, among other things. The U.S. Fish and Wildlife Service (USFWS) may grant a permit that allows the incidental take of an endangered species under the ESA, but the MBTA prohibits the take of migratory birds, including species listed under the ESA. Through its Division of Law Enforcement, the USFWS has the authority to take action against violators. Wind farms that violate the law without making an effort to significantly reduce the level of avian fatalities are at risk for enforcement action by the USFWS. Findings from NREL research completed over the past several years suggest that numerous factors affect avian/wind turbine interactions. Topography, weather, habitat, habitat fragmentation, urban encroachment, habitat loss, species abundance, distribution and behavior, and turbine location are some of the more important factors that may influence bird interactions with wind turbines. The nighttime activity of owls, migratory birds, and bats can also be a risk (Thelander 2000, Harmata 1998). NREL’s Avian Research studies have been conducted at various sites across the country. The results of these studies indicate that avian issues should not be a concern for future land-based wind farm development because potential problems can be identified and dealt with before micrositing (determining the specific location of the turbines and turbine strings across the wind resource area) occurs. As wind resources are developed across the country, developers will need to assess potential avian impacts before forging ahead with development. If fatalities occur in the developed wind resource area, it is important to consider the number of bird fatalities in proportion to the local population size. The absolute number of fatalities may not be as important as the impact on the population. For example, if 10 birds of a particular species are killed, it is important to know if this is out of a local population of 30 or 3,000. The overall impact of 10 birds being killed will be different depending on the size of the local population. The wind industry continues to address avian issues on a sitespecific basis. A study commissioned by the NWCC compares avian impacts from wind turbines with impacts to birds from other impact sources and concludes that although wind turbine collisions may account for 10,000-40,000 fatalities each year, other sources cause far more impact. For example, communication towers may cause 4 million to 50 million fatalities each year, and collisions with buildings and windows may contribute from 98 million to 980 million fatalities each year. The report also states that the National Audubon Society estimates avian fatalities due to house cats at 100 million birds per year. This report, Avian Collisions with Wind Turbines: A Summary of Existing Studies and Comparisons to Other Sources of Avian Collision Mortality in the United States, gathers information through a literature review with the purpose of putting wind turbine impacts to birds in perspective with impacts from other significant sources of avian impacts.
Other Biological Issues Any development project can affect the biological resources of the development site. This includes plants and animals that live, use, or pass through the site. The permitting or regulatory agency may require an assessment of these resources as part of the site evaluation.
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