Visual Impact Assessment

An aesthetic or visual resource assessment that supports the siting and development of a wind farm should contain the fundamental components needed to determine and evaluate the potential for visual impacts. Those basic components include:

• Characterization of the baseline or existing conditions. This usually requires a thorough, representative sampling of "before" photographs. It is suggested that these be from all directions and include near range, moderate range, and far range views of the project site.

• Photo simulations and "after" views superimposed into the "before" photographs, to the extent project elements will be visible after construction. Using precise three-dimensional data and digital photography, the simulations superimpose the proposed facilities on the existing landscape conditions. Visual simulations can offer an accurate depiction of the existing landscape with the addition of the project features, and provide a basis for characterizing the degree of visual contrast that would be created by the project.

• Specific investigation and documentation of the potential visual impacts of the project, based on identified changes from the baseline condition.

Visual receptors typically included in the assessment are residential and recreational areas, as well as sites of historic or cultural significance.

The characterization of the existing conditions should address both the existing landscape in the vicinity of the project and key variables applicable to viewers of that landscape. In some cases, the visual assessment approach includes defining the existing visual quality of the landscape, based on the form, line, color, and texture of the landscape and the evidence of human modification. Important information on viewer attributes includes the types and numbers of viewers (e.g., residents, workers, recreational, or highway travelers), their expected sensitivity to visual change, and typical viewing distances and durations. The study area is often divided into zones or units, based on landscape similarity conditions, and specific viewpoints or viewing locations are selected to represent typical or important views in each area.

Visual analysts typically determine the visibility of project facilities through three-dimensional analysis of the study area terrain and the physical dimensions of the project facilities (primarily the wind turbines). This allows identification of the areas in which viewers might respond to visual contrast created by the project, and the areas in which terrain and vegetation would block or screen views of project facilities. Using pre-

Simulation of a hypothetical wind project at a typical location in the Intermountain West. Simulated turbines are at distances of approximately 1.75 to 3 miles from the observer. Simulation courtesy of Tetra Tech EC, Inc.

and post-project conditions for key viewpoints, the analysts define as precisely as possible the degree of visual contrast that would occur in those areas where project facilities would be visible. One or more visual simulations are typically employed as an important tool for this step of the assessment.

Once the visual contrast of the project has been determined, the impact analysis then relates that information to the applicable viewer characteristics. For example, the analysis might indicate that project wind turbines would be prominent and introduce considerable visual contrast from some reference viewpoints, but that those views would be at a long distance and/or would be experienced by few viewers. In such a case, the analysis would likely characterize the potential visual impact as relatively minor. Conversely, a case of pronounced visual contrast in relatively near views experienced by a large number of viewers would indicate the potential for widespread local concern over project visual impacts.

The electrical facilities needed to transfer power from a wind farm to a local or regional electrical system also represent potential sources of visual impact from a wind farm. These facilities expand the area of project visibility and also are a potential source of visual impact. The visibility analysis for a proposed wind farm should include the project transmission line(s) (and any other overhead electrical lines proposed as part of the project) and substation(s). Wind project substations are relatively low in profile and modest in size, and therefore are less prominent visually than wind turbines. Unless the visibility analysis indicates that these ancillary facilities would have limited or no visibility, the visual simulations for a project usually includes representative views of the project transmission line(s) and substation(s).

Large-scale wind energy facilities generally require rather extensive project road systems to provide construction and operation access to the locations of the turbines and support facilities. Because roads can also contribute substantially to the visual impact of a project, they should be addressed in the visual impact analysis. The analysis should pay particular attention to visually sensitive location relative to slopes.

As described in Section 4.1.5, the FAA requires specific lighting depending upon the project location. The requirement to install safety lighting (on both turbines and meteorological towers) adds to the visibility of a wind project and can contribute to its visual impact. Most wind farms currently in operation have flashing white lights that add to the daytime visibility of the project. For new projects developed under the current FAA guidelines, the visual impact of safety lighting is limited to nighttime. The flashing red lights can be conspicuous at long distances when viewed against dark skies, and the practice of synchronous flashing of the lights tends to better define the areal extent of the wind farm. The appearance of a wind farm at night, particularly with synchronized flashing of red lights, is difficult to simulate photographically. Nevertheless, the visual impact analysis should acknowledge and try to characterize this aspect of project visibility.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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