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Environmental Impacts of Wind-Energy Projects 4 Impacts of Wind-Energy Development on Humans INTRODUCTION Although they have some unusual characteristics, such as visibility at a distance, wind-energy projects are not unique in their impacts on people. They share many characteristics with other projects—not only energy-production projects but also landfills, waste incinerators, etc.—that create both benefits and burdens. In considering how to undertake local interactions and how to temper negative socioeconomic impacts while enhancing benefits, much can be learned from past experiences with other potentially controversial issues. One important lesson—and an important prelude to this chapter—is that concern about visual, auditory, and other impacts is a natural reaction, especially when the source of the impacts is or will be close to one’s home. The project’s potential for negative impacts as well as benefits, and the fact that different people have different values as well as different levels of sensitivity, are important aspects of impact assessment. This chapter addresses some key potential human impacts, positive and negative, of wind-energy projects on people in surrounding areas. The impacts discussed here include aesthetic impacts; impacts on cultural resources such as historic and archeological sites and recreation sites; impacts on human health and well-being, specifically, from noise and from shadow flicker; economic and fiscal impacts; and the potential for electromagnetic interference with television and radio broadcasting, cellular phones, and radar. The topics covered in this chapter do not represent an exhaustive list
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Environmental Impacts of Wind-Energy Projects of all possible human impacts from wind-energy projects. For example, we have not addressed potentially significant social impacts on community cohesion, sometimes exacerbated by differences in community make-up (e.g., differences in values and in amounts and sources of wealth between newcomers and long-time residents). Also not covered are psychological impacts—positive as well as negative—that can arise in confronting a controversial project (Gramling and Freudenburg 1992; NRC 2003). We have not focused on these matters because they can vary greatly from one local region or project site to another; and also as a function of population density and local and regional economic, social, and economic conditions; and in other ways. As a result, it is very difficult to generalize about them. In addition, not covered in this chapter but discussed elsewhere in this report (see especially Chapter 2) are diffuse health and economic effects of wind-energy projects. The topics covered in this chapter are, however, the chief local environmental impacts that have been recognized to date. Thus far, there has been relatively little dispassionate analysis of the human impacts of wind-energy projects. Much that has been written has been from the vantage points of either proponents or opponents. There also are few data that have been systematically gathered on these impacts. In the absence of extensive data, this chapter is focused mainly on appropriate methods for analysis and assessment and on recommended practices in the face of uncertainty. Several of the methods discussed follow general principles and practice in socioeconomic impact assessments conducted as part of environmental impact statements; nevertheless, the chapter is tailored to the potential local human impacts of wind-energy projects and to their predominantly rural settings. Wind-energy projects, like other potentially controversial developments, vary in their social context and thus in their social complexity. In this chapter, comments and methodological recommendations are directed toward relatively complex wind-energy facilities such as those being proposed for the Mid-Atlantic Highlands. While still applicable to smaller, less controversial installations, recommended methods should be simplified accordingly. AESTHETIC IMPACTS Aesthetics is often a primary reason for expressed concern about wind-energy projects (Figure 4-1). Unfortunately, few regulatory review processes adequately address aesthetic issues, and far fewer address the unique aesthetic issues associated with wind-energy projects in a rational manner. This section begins by describing some of the aesthetic issues associated with wind-energy projects. It then discusses existing methods for identifying visual resources and evaluating visual impacts in general, and it
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Environmental Impacts of Wind-Energy Projects FIGURE 4-1 View of Mountaineer Project from .5 mile. The project includes a total of 44 wind turbines. SOURCE: Photograph by Jean Vissering. provides recommendations for adapting those methods to the assessment of visual impacts associated with wind-energy projects. Finally, the section briefly examines the potential for developing guidelines to protect scenic resources when planning for, siting, and evaluating prospective wind-energy projects. Visual impacts are the focus of this discussion of aesthetic impacts, but noise is considered to the extent that it is related to the overall character of a particular landscape. Noise and shadow flicker are discussed further in this chapter, under the section addressing potential impacts on human health and well-being associated with wind-energy projects. Aesthetic Issues The essence of aesthetics is that humans experience their surroundings with multiple senses. We often have a strong attachment to place and an inherent tendency to protect our “nest.” Concern over changes in our personal landscapes is a universal phenomenon; it is not limited to the United States or to the present day. Public perceptions of wind-energy projects vary widely. To some, wind turbines appear visually pleasing, while others view them as intrusive industrial machines. Unlike some forms of development (e.g., cell towers), there are many people who find wind turbines to
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Environmental Impacts of Wind-Energy Projects be beautiful. Nevertheless, even beautiful objects may not be desirable in one’s current surroundings. Research has shown strong support for wind energy generally but substantially less support for projects close to one’s home (Thayer and Hansen 1989; Wolsink 1990; Gipe 2002). There are a number of reasons why proposed wind-energy projects evoke strong emotional reactions. Modern wind turbines are relatively new to the United States. Some of the early projects were built in remote areas, but increasingly, they are being built in or proposed for areas that are close to residential and recreational uses, and often in areas never before considered for industrial land uses. They must be sited where wind resources, transmission lines, and access exist; in some cases, particularly in the eastern United States, these sites are relatively high in elevation (e.g., mountain ridgelines) and highly visible. Some projects extend over fairly extensive land areas, though only small portions of the area are occupied by the turbines themselves. The turbines1 often are taller than any local zoning ordinance ever envisioned, and they are impossible to screen from view. The movement of the blades makes it more likely that they will draw attention (Thayer and Hanson 1988; Gipe 2002). Federal Aviation Administration obstruction lighting (pulsing red or white lights at night) is another aesthetic issue, and one that may result in some of the greatest aesthetic concerns (Hecklau 2005). In addition, wind turbines may produce noise, and the movement of the blades can result in shadow flicker from certain vantage points. Both the noise and the shadow flicker can be aesthetically troubling for some people who live nearby. While less concern has been raised about other project infrastructure such as meteorological towers, roads, power lines, and substations along with their associated site clearing and regrading, these can also result in negative visual impacts. Finally, a lack of regulatory guidance and stakeholder participation can contribute to fears of cumulative impacts if numerous projects are within a single viewshed. Based on the few studies that have been conducted, it appears that despite low public acceptance during the project-proposal phase, acceptance levels generally have increased following construction (Thayer and Hanson 1989; Wolsink 1990; Palmer 1997). It is possible to find communities that identify their local wind projects as tourist attractions. Part of the positive image many people hold is linked to wind energy’s “green image” and spe- 1 Currently (late 2006), the most common commercial turbines being installed in the United States are 1.5 MW machines, usually 65-80 meters tall to the center of the rotor with rotor diameters of around 70 meters. The material in this chapter applies to turbines of this size. At several sites in the United States, 2.5 MW turbines are being used but are not yet in wide-spread use.
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Environmental Impacts of Wind-Energy Projects cifically to its potential for replacing CO2-emitting electricity sources, with the hopeful prospect of reducing air pollution and global warming. When evaluating the visual impacts of wind-energy projects, the essential question is not whether people will find them beautiful or not, but instead to what degree they may affect the important visual resources in the surrounding area. It is impossible to predict how any one individual will react to a wind-energy project. It is, however, possible to identify the visual character and scenic resources of a particular site and region. Evaluating the aesthetic impacts of wind-energy projects needs to focus on the relationship of the proposed project to the scenic landscape features of the site and its surrounding context. The factors that contribute to scenic quality can be identified and described with reasonable accuracy (Appleton 1975; Zube and Mills 1976; Litton 1979). This is especially true when viewing natural landscapes. Preferences are harder to predict for altered landscapes, although particular qualities of such landscapes have been identified in research of human preferences (Palmer 1983; Smardon et al. 1986). Nevertheless, we know enough to develop meaningful processes for reviewing aesthetic impacts. Despite the tremendous importance of a wind-energy project’s aesthetic impacts, especially on nearby residents, this issue is too often inadequately addressed. Current Information There is a growing body of information concerning the aesthetic impacts of wind-energy projects. The National Wind Coordinating Committee (NWCC) provides general outlines of aesthetic issues and some examples of local ordinances addressing wind-energy projects. The latter are very basic and do not address the broader issues of protecting particular landscape values. More comprehensive are the Proceedings of the NWCC Siting Technical Meeting (December 2005), which cover a range of relevant topics and provide a useful bibliography. The visual issues are addressed at length by Pasqualetti et al. (2002). While providing an excellent overview, that book predates the use of modern 1.5-3 MW turbines. And while it provides excellent guidance for mitigating impacts, it does not address siting or landscape characteristics. Research on public perceptions of specific wind-energy projects is fairly common in Europe (both pre- and post-construction studies), but there are fewer examples in the United States (Stanton 2005). Of those in the United States, most are focused on western landscapes (Thayer and Hansen 1989), while few are focused on eastern landscapes, including wooded ridgelines. While such studies are useful in understanding public reactions generally, visual impacts are largely site-specific (Pasqualetti 2005). Other available resources include legal and regulatory guidelines for review of wind-energy projects. New York’s State Environmental Quality Review Act (SEQRA) is one of the more explicit in the eastern United
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Environmental Impacts of Wind-Energy Projects States in terms of specifying what applicants need to submit and what will be considered (NYSDEC 2005; NYSERDA 2005a). Maine’s Department of Environmental Protection adopted similar language in its environmentalreview process (MEDEP 2003). In addition, there are several visual resource methods used for identifying scenic landscapes and for addressing visual impacts. Some important ones are discussed below. Visual Assessment Methods Two complementary approaches have been used to identify scenic resources and assess the impacts of proposed development projects. The first often is called a “professional approach” and relies on an individual or group with training in visual-resource and visual-impact assessment. These assessments rely on the research concerning human perceptions of landscapes (USFS 1979; Smardon et al. 1986) and on the adaptation of well-established methods for evaluating scenic landscape quality and for assessing visual impacts on particular landscapes. The second approach involves an assessment of public perceptions, attitudes, and values concerning a proposed project and its visual impacts on scenic resources. Landscapes are complex and imbued with cultural meaning that may not be understood by outside professionals. Techniques for assessing public perceptions, values, and attitudes include surveys, public meetings, interviews, and forums as well as examination of public documents identifying valued scenic resources (Smardon et al. 1986; Priestley 2006). Among the best known and established methods for evaluating the scenic attributes of landscapes are the Visual Management System (USFS 1974) and the later Scenery Management System (USFS 1995) established by the U.S. Forest Service (USFS). Similarly, the U.S. Bureau of Land Management (BLM) uses a method called Visual Impact Assessment. The USFS and the BLM assessment methods have been used and adapted by numerous state and local agencies either for planning purposes (e.g., identifying scenic landscapes) or for assessing the impacts of proposed projects such as highways, ski areas, power plants, and forest harvesting (MADEM 1982; Smardon et al. 1986; RIDEM 1990). While these methods are useful starting points, federal agencies such as the USFS usually go further in managing visual impacts on federal lands: they generally have plans in place that identify scenic values and set acceptable thresholds for alterations to the landscape. Even with detailed plans, these methods often fall short of providing meaningful guidance for evaluating the visual impacts of projects such as wind-energy facilities. Most wind-energy projects are proposed on private land where there is far less guidance, especially with respect to evaluating aesthetic impacts. Many regulatory requirements adopted by states focus only on the tools for understanding the visibility of projects and fail to describe how visual im-
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Environmental Impacts of Wind-Energy Projects pacts should be evaluated. In other words, most processes are not very successful in addressing questions of what landscape or project characteristics would make a project aesthetically unacceptable or the impacts “undue.” Below we outline a process for evaluating the conditions under which the aesthetic impacts of a proposed wind project might become unacceptable or “undue” in regulatory terms. An Assessment Process for Evaluating the Visual Impacts of Wind-Energy Projects The following steps summarize a process for moving from collecting measurable and observable information about visibility and landscape characteristics to analyzing the significance and importance of the visual resources involved and the effects of the proposed project on the landscape character and scenic resources of the surrounding area. Finally and most important, this process helps to inform the regulatory process about whether a proposed project is acceptable as designed, potentially acceptable with appropriate mitigation techniques, or unacceptable. The steps outlined below are described in greater detail in Appendix D. Project Description All site alterations that will have potential visual impacts must be identified by the developer in detail. These should include the turbine characteristics (height, rotor diameter, color, rated noise levels, proposed lighting) as well as the number of turbines and their locations; meteorological towers; roads; collector, distribution, and transmission lines; permanent and temporary storage “laydown” areas; substations; and any other structures associated with the project. In addition, all site clearings should be identified, including clearings for turbines, roads, power lines, substations, and laydown areas. All site regrading should be presented in sufficient detail to indicate the amount of cut and fill, locations, and clearing required. This information forms the basis for the visual assessment. Project Visibility, Appearance, and Landscape Context Viewshed mapping, photographic and virtual simulations, and field inventories of views are useful tools for determining with reasonable accuracy the visibility of the proposed project and for describing the characteristics of the views as well as identifying distinctive features within views (see Appendix D for more detail). Viewshed maps show areas of potential project visibility based on digital-elevation modeling. The modeling also can be used to determine the number of turbines that would be visible from a par-
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Environmental Impacts of Wind-Energy Projects ticular viewpoint. Actual visibility must be field-verified as trees, buildings, and other objects may restrict views. Field inventories also are necessary to document descriptive characteristics of the view. Inventories normally focus on areas of public use within a 10-mile radius of a project (Box 4-1). These include public roads, recreation areas, trails, wilderness and natural areas, historic sites, village centers, and other important scenic or cultural features identified in planning documents or in public meetings. Photomontages or simulations provide critical project information for analysis. They should most usefully illustrate visually sensitive viewpoints and a range of perspectives and distances. They should also illustrate “worst-case” conditions to the greatest extent possible (clear weather and leaf-off conditions). Excellent software is available for creating simulations, but the technical requirements for accuracy should be clearly understood and specified (see Appendix D). Identifying impacts from private residences can be more difficult without entering private property. Viewshed mapping can identify potential visibility. Geographic Information System (GIS) data generally provide additional information concerning existing vegetation and structures along with their primary use (residence, camp, or business). Providing regular notices to residents within a certain distance of the project can offer a means of learning more about visibility from private properties. BOX 4-1 Area of Assessment: 10-Mile Radius The size of the area for analysis may vary from location to location depending on the particular geography of the area and on the size of the project being proposed. Modern wind turbines of 1.5-3 MW can be seen in the landscape from 20 miles away or more (barring topographic or vegetative screening), but as one moves away from the project itself, the turbines appear smaller and smaller, and occupy an increasingly small part of the overall view. The most significant impacts are likely to occur within 3 miles of the project, with impacts possible from sensitive viewing areas up to 8 miles from the project. At 10 miles away the project is less likely to result in significant impacts unless it is located in or can be seen from a particularly sensitive site or the project is in an area that might be considered a regional focal point. Thus, a 10-mile radius provides a good basis for analysis including viewshed mapping and field assessment for current turbines. In some landscapes a 15-mile radius may be preferred if highly sensitive viewpoints occur at these distances, the overall scale of the project warrants a broader assessment, or if more than one project is proposed in an area. In the western United States, landscape scale and visibility may require a larger area of assessment.
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Environmental Impacts of Wind-Energy Projects Scenic Resource Values and Sensitivity Levels Some landscapes are more visually sensitive than others due to such factors as numbers of viewers, viewer expectations, and identified scenic values. Processes exist for determining the relative visual quality of landscapes, the features that contribute to visual quality, and the sensitivity levels of particular landscape features and their uses. These are outlined in Appendix D and also can be found in methods used by the USFS Visual Management System (USFS 1974) and its later Scenery Management System (USFS 1995). Scenic resources values can also be determined in public planning documents and through public meetings. Assessment of Visual Impacts Visual impacts vary considerably depending on the particular characteristics of the project and its landscape context. Visibility of a project is only one of many variables that should be examined. Significant visual impacts generally arise because of the combination of many factors such as proximity of views, sensitivity of views, duration of views, the presence of scenic resources of statewide or national significance, and the scale of the project in relation to its setting (see Appendix D). Some examples of potentially significant impacts might include the following: The project is located within a scenic context and is viewed in close proximity, for an extended duration (e.g., broad area or linear miles) from a highly sensitive use area, especially one for which the enjoyment of natural scenery is important, and that is an identified resource of statewide or national significance. The project is located on a landform that is an important focal point that is highly visible throughout the region. The project is of a scale that would dominate views throughout a region (or 10-mile assessment area) so that few other scenic natural views would be possible without including turbines. Mitigation Techniques A well-designed project will incorporate a number of techniques into the planning and design of the project to minimize visual impacts, including sensitive siting and ensuring that project infrastructure is well screened from view. Establishing “Best Practice” Guidelines can help ensure that minimum standards are met before project permit applications are submitted. Nevertheless, a thorough review by interested parties may result in further adjustments. If the visual impacts are deemed unacceptable, additional
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Environmental Impacts of Wind-Energy Projects mitigation techniques can be explored (see Appendix D). In some cases, however, mitigation techniques may not solve inherent concerns, and the project may be found to have “undue aesthetic impacts.” Determination of Unacceptable or Undue Aesthetic Impacts Guidance on when projects may be found unacceptable tends to be lacking or inadequate in many review processes. The information gathered in the above process can inform this decision by providing a detailed understanding of the particular issues involved in the visual relationship between the project and its surrounding context. Appendix D provides questions that could help determine the degree of visual impact. Among the factors to consider are: Has the applicant provided sufficient information with which to make a decision? These would include detailed information about the visibility of the proposed project and simulations (photomontages) from sensitive viewing areas. New York’s SEQRA process offers an example of clearly identifying the information required and the mitigation measures that need to be considered. Are scenic resources of local, statewide, or national significance located on or near the project site? Is the surrounding landscape unique in any way? What landscape characteristics are important to the experience and visual integrity of these scenic features? Would these scenic resources be significantly degraded by the construction of the proposed project? Would the scale of the project interfere with the general enjoyment of scenic landscape features throughout the region? Would the project appear as a dominant feature throughout the region or study area? Has the applicant employed reasonable mitigation measures in the overall design and layout of the proposed project so that it fits reasonably well into the character of the area? Would the project violate a clear, written community standard intended to protect the scenic or natural beauty of the area? Such standards can be developed at the community, county, region, or state level. Guidelines for Protecting Scenic Resources Planning and Siting Guidelines Siting guidelines that prospectively identify suitable and unsuitable locations for wind-energy projects have been considered in many regions. Problems with such guidelines arise, however. Each site is visually different,
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Environmental Impacts of Wind-Energy Projects local attitudes toward wind-energy development vary, and a wind developer must grapple with several non-aesthetic factors in locating a potentially developable site (e.g., willing property lessors, adequate wind resources, access to transmission lines, and a market for the electricity generated). Several combined approaches may be the most feasible. As discussed in more detail in Chapter 5, they would include the following: State and regional guidance providing criteria concerning site conditions that may be inherently suited or unsuited to wind development due to particular scenic values, and/or sensitivity levels that would raise concerns requiring additional detailed study. Policies regarding aesthetic conditions and wind development on state-owned lands would also be appropriate. Local and state planning documents that identify valuable scenic, recreational, and cultural assets. Defining particular landscape attributes or other public values that contribute to the resources is helpful when making decisions concerning proposed landscape development proposals.2 In addition, insofar as a “comprehensive plan” is voted on by the local governing body, the plan may provide guidance to a developer as an expression of the will of the community. Statewide policies that address the relationship between the development of wind energy and the protection of valuable scenic resources. Guidelines for Evaluating Cumulative Aesthetic Impacts While wind-energy development is relatively new in the United States, the potential for cumulative aesthetic impacts resulting either from several new projects in a particular region or from expansion of existing projects is likely to become an issue that may need to be addressed at local, regional, and state levels. The following questions could help to evaluate the potential for undue cumulative aesthetic impacts: 2 Clear and reasonably objective guidance is more useful than vague statements such as “the ridgelines in our town are valuable to our rural character and no development is allowed.” A statement that identifies the resource(s), its particular valued attributes, and appropriate and inappropriate development characteristics provides a clear written community standard. Statements that exclude wind development are generally not appropriate unless clear reasons are provided for this exclusion. For example, “the Town of Jonesville is characterized by the Green Range, which is composed of numerous hills and ridges. Several of the hills stand out because of their distinct shapes, including Mount Grant, Morris Mountain, and Jones Peak. Mount Grant is also valued for a popular hiking trail and the spectacular views looking west…” Such statements provide helpful guidance in decision making. In other words, a project located on another ridge but out of the view from the summit of Mount Grant might be acceptable, whereas a wind project located on Mount Grant probably would not be.
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Environmental Impacts of Wind-Energy Projects The director of economic development in Lake Benton, Minnesota, said that each 100 MW of wind development generates about $1 million annually in property-tax revenue. In addition, as with the private economy, the wind-energy project may indirectly generate taxes for the local government. However, as discussed above with regard to the private economy, an assessment of fiscal benefits in the form of tax revenue should be based on changes that would occur if the project was built versus if it was not built. The project may encourage some forms of economic development that generate taxes, but it may deter others. A wind-energy facility also may entail public costs. Some of these, such as improvements of local public roads accessing the facility, will be obvious. Others, such as improved community services that may be expected in the wake of the development, will be indirect and less obvious. Taken together, the costs to a small, rural government have the potential to be significant. Fiscal Commitments The developer and the local government should have a clear mutual understanding of both the basis for tax revenues and what public expenditures are expected to make the project possible. ELECTROMAGNETIC INTERFERENCE Through electromagnetic interference (EMI), wind-energy projects conceivably can have negative impacts on various types of signals important to human activities: television, radio, microwave/radio fixed links, cellular phones, and radar. EMI is electromagnetic (EM) disturbance that interrupts, obstructs, or otherwise degrades or limits the effective performance of electronics or electrical equipment. It can be induced intentionally, as in some forms of electronic warfare, or unintentionally, as a result of spurious emissions and responses and intermodulation products. In relation to wind turbines, two issues are relevant: (1) possible passive interference of the wind turbines with existing radio or TV stations, and (2) possible electromagnetic emissions produced by the turbines. There are several ways in which electromagnetic waves can deviate from their intended straight-line communication paths. These include: Blocking the path with an obstacle, thus creating a “shadow” or area where the intended EM wave will not occur. To a large extent, the
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Environmental Impacts of Wind-Energy Projects “blocking” depends on the size of the obstacle as a function of the wave-length of the electromagnetic wave. Refraction of the EM wave. Refraction is the turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another with different refractive properties. In the context of wind-energy projects, EMI often is discussed in relation to the following telecommunications facilities: Television broadcast transmissions (approx 50 MHz-1 GHz) Radio broadcast transmissions (approx 1.5 MHz [AM] and 100 MHz [FM]) Microwave/radio “fixed links” (approx 3-60 GHz) Mobile phones (approx 1 or 2 GHz) Radar Television The main form of interference to TV transmission caused by wind-energy projects is the scattering and reflection of signals by the turbines, mainly the blades. In relation to the components that make up a wind turbine, the tower and nacelle have very little effect on reception (i.e., only a small amount of blocking, reflection, and diffraction occurs). This is backed up by laboratory measurements that show that the tower introduces only a small, localized (up to approximately 100 m) attenuation of the signal (Buckley and Knight Merz 2005). The British Broadcasting Corporation has issued recommendations based on a simple concept for calculating the geometry associated with reflected signals from wind turbines and how directional receiving aerials can provide rejection of the unwanted signals (BBC 2006). Typical mitigation requirements include: Re-orientation of existing aerials to an alternative transmitter Supply of directional aerials to mildly affected properties Switch to supply of cable or satellite television (subject to parallel broadcast of terrestrial channels) Installation of a new repeater station in a location where interference can be avoided (this is more complex for digital but also less likely to be required for digital television)
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Environmental Impacts of Wind-Energy Projects Radio Available literature indicates that effects of wind projects on both Amplitude Modulated (AM) and Frequency Modulated (FM) radio transmission systems are considered to be negligible and only apply at very small distances from the wind turbine (i.e., within tens of meters). For AM transmissions, this is due to low broadcast frequencies and long (100+ meter) signal wavelengths, which makes distortion difficult even for very large wind turbines. For FM transmissions, this is due to the fact that ordinary FM receivers are susceptible to noise interference only while operating in the threshold regions relative to signal-to-noise ratios. Thus, a distorted audio signal may be superimposed on the desired sound close to a wind turbine, potentially causing interference, only if the primary FM signal is weak. Fixed Radio Links Fixed radio links, also known as point-to-point links, are by definition a focused radio transmission directed at a specific receiver. Fixed links are not intended to be picked up by any receivers other than those at which they are directed. They typically rely on the use of a parabolic reflector antenna (like satellite dishes) to transmit a direct narrow beam of radio waves to a receiving antenna. A direct line of sight is required between the transmitter and receiver, and any obstructions within the line of sight may degrade the performance or result in the loss of the link. A wind turbine may degrade the performance of a fixed link, not only if it is within the line of sight of the link but also if it is within a certain lateral distance of the link, known as the “Fresnel Zone.” Cellular Phones Mobile-phone reception depends greatly on the position of the mobile receiver. Therefore, the movement of the receiver and the topography—including both natural and unnatural obstacles—have a major impact on the quality of the signal. The mere movement of the receiver can ensure that wind turbines will have a very minimal effect, if any, on communication quality. Radar The potential for interference of wind turbines with radar is only partially understood. If there is such interference, it would primarily af-
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Environmental Impacts of Wind-Energy Projects fect military and civilian air-traffic control. In addition, National Weather Service weather radars might be affected. Two recent reports treated the problems in some detail. The first is a report by the U.S. Department of Defense to the U.S. Congressional Defense Committees (DOD 2006). The second is a British report on the impacts of wind-energy projects on aviation radar (Poupart 2003). The DOD report concludes that “[w]ind farms located within radar line of sight of air defense radar have the potential to degrade the ability of the radar to perform its intended function. The magnitude of the impact will depend upon the number and locations of the turbines. Should the impact prove sufficient to degrade the ability of the radar to unambiguously detect objects of interest by primary radar alone this will negatively influence the ability of U.S. military forces to defend the nation.” It concludes further that “[t]he Department has initiated research and development efforts to develop additional mitigation approaches that in the future could enable wind turbines to be within radar line of sight of air defense radars without impacting their performance.” The U.K. report focused on the development and validation of a computer model that can be used to predict the radar reflection characteristics, which are a function of the complex interaction between radar energy and turbines. These effects are described by the Radar Cross Section (RCS). The report concludes that the model enables a much more detailed quantification of the complex interaction between wind turbines and radar systems than was previously available. Among the findings are: Wind-turbine towers and nacelles can be designed to have a small RCS. Blade RCS returns can be effectively controlled only through the use of absorbing materials (stealth technology). The key factors influencing the effect of wind-energy facilities on radar are spacing of wind turbines within a facility, which needs to be considered in the context of the radar cross-range and down-range resolutions. No optimal layout or format can be prescribed, because each wind-energy facility will have its own specific requirements that depend on many factors. The report concludes that the model has a large potential for further use, such as the following: It can generate the detailed data required for sophisticated initial screening of potential facility sites. It can support the development of mitigation and solutions, in-
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Environmental Impacts of Wind-Energy Projects cluding siting optimization, control of wind-turbine RCS, and the development of enhanced radar filters that are able to remove returns from wind turbines. It is clear that as of late 2006, the interference of wind turbines with radars is a problem as yet unsolved. Research and larger-scale investigations are currently under way in several countries; they may eventually lead to standardization and certification procedures. CONCLUSIONS AND RECOMMENDATIONS Aesthetic Impacts Wind-energy facilities often are highly visible. Responses to proposed wind projects based on aesthetics are among the most common reasons for strong reactions to them. Reactions to the alteration of places that contribute to the beauty of our surroundings are natural and should be acknowledged. Excellent methods exist for identifying the scenic resource values of a site and its surroundings, and they should be the basis for visual impact assessments of proposed projects. Tools are available for understanding project visibility and appearance as well as the landscape characteristics that contribute to scenic quality. Lists of potential mitigation measures are also readily available. Nevertheless, the difficult step of determining under what circumstances and why a project may be found to have undue visual impacts is still poorly handled by many reviewing boards. The reasons include a lack of understanding of visual methods for landscape analysis and a lack of clear guidelines for decision making. Current Best Practices Information concerning best practices in the United States is found through the NWCC and its sponsored proceedings and links. Europe and Canada generally have done a more thorough job in providing definitive best-practice guidelines. The integration of local, regional, and national planning and review efforts in those countries contributes to the success of their review processes. Funding in those nations for planning and more extensive surveys of public perceptions of wind energy is also far ahead of that in the United States. Here, standards for best practices are evolving as communities and states recognize the need for a more systematic approach to evaluating visual impacts. There is considerable variability in the review of proposed projects.
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Environmental Impacts of Wind-Energy Projects Information Needs Processes for evaluating the aesthetic impacts of wind-energy projects should be developed with a better understanding of the aesthetic principles that influence people’s experience of scenery. Comparative studies are needed of wind-energy projects that have relatively widespread acceptance of their aesthetic impacts and those that do not. These studies could provide useful information about a range of factors that contribute to acceptability within different landscape types. These studies should take into account that sites and projects vary dramatically in the types of scenic resources involved; the proximity and sensitivity of views; and the particular project characteristics, including scale. The tradeoffs between placing wind-energy projects close to population centers where they are closer to electricity users but visible to more people, and placing them in remote areas where they are less visible but where the wilderness, remote, and undeveloped qualities of the landscape may hold value need discussion as well as a clear understanding of the tradeoffs involved. These issues need to be addressed broadly, not only singling out aesthetic concerns. Impacts on Recreational, Historic, Sacred, and Archeological Sites Wind-energy projects can be compatible with many recreational activities, but concerns may arise when they are close to recreational activities for which the enjoyment of natural scenery is an important part of the experience. Historic, sacred, and archeological resources can be harmed by direct impacts that affect the integrity of the resource or future opportunities for research and appreciation. The experience of certain historic or sacred sites or landscapes can also be indirectly affected by wind-energy projects, especially if particular qualities of the surrounding landscape have been documented as important to the experience, interpretation, and significance of the proximate historic or sacred site. Greater clarity is needed about how such situations should be evaluated. For example, the importance and special qualities of the experience must be assessed within the context of the relative visibility and prominence of the proposed wind-energy project. Current Best Practices Useful methods exist for evaluating both the relative sensitivity of recreational areas and recreational users, and for determining valuable scenic resources. Siting to avoid impacts on highly sensitive recreational uses, and project design to mitigate both direct and indirect impacts can be important. Mitigation techniques can include relocation of project design
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Environmental Impacts of Wind-Energy Projects elements, relocation of recreational activities (such as a trail), and enhancement of existing recreational activities. State Historic Preservation Offices (SHPOs) generally identify all known historic sites of state and national significance. Local historical societies or comprehensive plans may identify additional sites of local significance. The SHPO typically requires a Class II survey to determine the existence of unknown resources in areas where such surveys are lacking. Guidelines for evaluating direct impacts on historic sites and structures often are available, and many states require archeological surveys for certain sites. Few guidelines currently exist, however, for evaluating indirect impacts of wind-energy projects on historic or sacred sites and landscapes. Information Needs Research examining the perceptions of recreational users toward wind-energy projects that are located near dispersed and concentrated recreational activities would provide useful data for decision makers. However, aesthetic impacts are very site-specific, so the results of such research likely will be able to guide site-specific assessments but not substitute for them. Guidelines are needed concerning distances at which recreational activities can occur safely around wind turbines. Policy makers and decision makers need better guidance from historic-preservation experts and others concerning the methods for evaluating the effects of wind-energy projects on historic, sacred, and archeological resources. Noise and Shadow Flicker Noise can be monitored by various measurement techniques. However, an important issue to consider, especially when studying noise, is that its perception and the degree to which it is considered objectionable depend on individuals exposed to it. Shadow flicker caused by wind turbines can be an annoyance, and its effects need to be considered during the design of a wind-energy project. In the United States, shadow flicker has not been identified as even a mild annoyance. In Northern Europe, because of the higher latitude and the lower angle of the sun, especially in winter, shadow flicker has, in some cases, been noted as a cause for concern.
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Environmental Impacts of Wind-Energy Projects Best (or Good) Practices Good practices for dealing with the potential impacts of noise from a wind-energy project could include the following: Analysis of the noise should be made based on the operating characteristics of the specific wind turbines, the terrain in which the project will be located, and the distance to nearby residences. Pre-construction noise surveys should be conducted to determine pre-project background noise levels and to determine later on what, if any, changes the wind project brought about. If regulatory threshold levels of noise are in place, a minimum distance between any of the wind turbines in the project and the nearest residence should be maintained so as to reduce the sound to the prescribed threshold. To have a process for resolving potential noise complaints, a telephone number should be provided through which a permitting agency can be notified of any noise concern by any member of the public. Then, agency staff can work with the project owner and concerned citizens to resolve the issue. This process can also include a technical assessment of the noise complaint to ensure its legitimacy. Shadow flicker is reasonably well understood. With a little careful planning and the use of available software, the potential for shadow flicker can be assessed at any site, and appropriate strategies can be adopted to minimize the time when it might be an annoyance to residents nearby. Information Needs Recent research studies regarding noise from wind-energy projects suggest that the industry standards (such as the IEC 61400-11 guidelines) for assessing and documenting noise levels emitted may not be adequate for nighttime conditions and projects in mountainous terrain. This work on understanding the effect of atmospheric stability conditions and on sitespecific terrain conditions and their effects on noise needs to be accounted for in noise standards. In addition, studies on human sensitivity to very low frequencies are recommended. Computational tools have become available that not only compute shadow flicker in real time during turbine operation, but also convey information to the turbine-control system to allow shutdown if the shadow flicker at a particular location becomes particularly problematic. Hence, the development and implementation of a real-time system at a wind-en-
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Environmental Impacts of Wind-Energy Projects ergy project to take such actions when shadow flicker is indicated might be useful. Local Economic and Fiscal Impacts When assessing the economic and fiscal impacts of a wind-energy project, the main issues that arise include (1) fair treatment of both landowners who lease land for the project and other affected but uncompensated owners and occupants; (2) a fine-grained understanding of how wind-energy facilities may affect property values; (3) a realistic appraisal of the net economic effects of the wind-energy facility, during its construction and over its lifetime; and (4) a similarly realistic assessment of the revenues the local government can expect and the costs it will have to assume. Current Best Practices The guidelines referred to in the text—of Windustry, regarding leasing and easement arrangements; and of the NWCC, regarding assessments of economic development impacts of wind power—contain good advice and are examples of current standards for best practices. In addition, best practices include: Gathering as much “hard” information as possible: the terms of the lease and easement arrangements; the type, pay scale, and duration of jobs that are likely to be generated for local workers; the taxes that the project will directly generate; and the known public costs that it will entail. Qualitatively taking into account other, less tangible economic factors: opportunity costs that may arise from the project; the duration of benefits from the project; and the likelihood of an uneven distribution of benefits (e.g., one landowner may realize income by leasing land for a turbine while another may be within close range of the turbine but receive no income). Adopting guarantees and mitigation measures that are tailored to the facility, the surrounding community members, and the local government and are fair to all involved. Information Needs Large wind-energy facilities are fairly new in the United States. Many current analyses of their economic impacts are fueled by enthusiasm or skepticism. There is a need for systematic collection and analysis of economic data on a facility-by-facility and region-by-region basis. These data should take into account the type of facility, including the number of tur-
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Environmental Impacts of Wind-Energy Projects bines at the facility and elsewhere in the region. The data should cover the following types of information: Leasing arrangements Jobs directly created (including skill and pay levels, duration, hiring policies) Local government revenue and costs Economic mitigation and enhancement measures More studies also are needed of public attitudes toward specific wind-energy facilities and how they affect economic behavior (e.g., property values, tourism, new residential development). To allow for cross-facility and longitudinal comparisons, the methods of data collection and analysis used in these studies should be replicable. Electromagnetic Interference With the exception of radar, the main EMI effects of wind-energy projects are well understood. Wind turbines have the potential to cause interference to television broadcasts, while the audio parts of TV broad-casts are less susceptible to interference. The data available are adequate to predict interference effects and areas and to minimize interference at the planning stage or propose suitable mitigation requirements. Information Needs Regarding radar, more research is needed to understand the conditions under which wind turbines can interfere with radar systems and to develop appropriate mitigation measures. In addition, while EMI is not an issue in all countries (e.g., it is not an issue in Denmark), EMI issues should be given sufficient coverage in environmental impact statements and assessments to provide adequate evaluation of wind-energy project applications. GENERAL CONCLUSIONS AND RECOMMENDATIONS Well-established methods are available for assessing the positive and negative impacts of wind-energy projects on humans; these methods enable better-informed and more-enlightened decision making by regulators, developers, and the public. They include systematic methods for assessing aesthetic impacts, which often are among the most-vocalized concerns expressed about wind-energy projects.
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Environmental Impacts of Wind-Energy Projects Because relatively little research has been done on the human impacts of wind-energy projects, when wind-energy projects are undertaken, routine documentation should be made of processes for local interactions and impacts that arise during the lifetime of the project, from proposal through decommissioning. Such documentation will facilitate future research and therefore help future siting decisions to be made. The impacts discussed in this chapter should be taken within the context of both the environmental impacts discussed in Chapter 3 and the broader contextual analysis of wind energy—including its electricity production benefits and limitations—presented in Chapter 2. Moreover, the conclusions and recommendations presented by topic here should not be taken in isolation; instead, they should be treated as part of a process. Chapter 5 elaborates on processes for planning and evaluating wind-energy projects and for public involvement in these processes. Finally, the text of this chapter describes many specific questions to be asked and issues to be considered in assessing various aspects of the effects of wind-energy projects on humans, especially concerning aesthetic impacts, and those questions and issues should be covered in assessments and regulatory reviews of wind-energy projects.
Representative terms from entire chapter: