Building Scenarios

A viewshed analysis was conducted for each of the 53 proposed solar facilities. There were 53 facilities in the All Proposed scenario, 21 facilities in the SESA scenario, and 10 facilities in the Fast Track scenario. Each analysis was conducted using the solar facility as the observation point, under the assumption that the landscape visible from the facility would be the same as the locations on the landscape from which the facility was visible. The observation point was placed on the ground in the center of the facility. The Viewshed Analysis tool in ArcGIS outputs a single raster for each facility, indicating the land that is visible from the facility (i.e., the facility’s visual footprint), and the land that is not visible from the facility. We overlayed the facilities included in each scenario to determine the overall visual footprint of the scenario.

The following assumptions are inherent in our analysis. We utilized a single observation point in the center of solar facilities ranging from several hundred to thousands of acres, which could underestimate a facility’s visual footprint. Second, the observation point was placed on the ground even though some facility infrastructure may reach much greater heights. This could also result in underestimates. For example, dish/engines are about 40 feet tall, while the three proposed facilities that plan to utilize power tower technology provide tower, the tallest element of the facility, heights of 312, 459, and 653 feet tall. Last, the DEM under the facility was not modified in any way, even though developers are likely to make modifications to the landscape, such as grading to reduce the slope of the land. Whether this assumption over- or underestimates a facility’s visual footprint is likely dependent on individual facility sites. Overall, our analysis most likely significantly underestimates the visual impact of the individual facilities and the three scenarios.