Environmental Considerations for Large-Scale Solar Installations in the Desert Southwest
Godfrey, Peter; Ludwig, Noel; and Salve, Rohit
Development of utility-scale solar energy installations (USSIs) (i.e., those generating at least 20 MW) is a key goal of federal and state governments in the U.S. In southern California alone, approximately 35 USSIs have recently been approved, or are currently being processed, by the Bureau of Land Management. These include the three current large-scale solar technologies: parabolic troughs, a type of concentrated solar power (CSP) that uses heat to generate electricity, power towers (also a CSP), and photovoltaic (PV) which converts solar energy directly into electricity. Common to all USSIs is the use of large land areas (i.e., ~1 km2 per 20-60 MW) across which collectors can capture solar energy.
Many of the proposed projects, and those currently under development, are in arid environments of the southwestern United States. They pose a range of environmental issues as they are constructed, operated, and ultimately dismantled. Some of these are technology specific, such as the potential for toxic fluid spills at CSP facilities, while others stem from the relatively large footprint of USSIs, and the potential impact to existing land-uses or ecological functions. Other concerns are a result of the environment itself, as is the case for water usage in a desert landscape. Environmental impacts from USSIs are expected to vary during the life of a project, with the most noticeable effects to the biological, soil, water, and air resources anticipated during the construction phase. Construction begins with clearing and grading of the landscape, which may result in soil compaction, alteration to drainage channels, and the potential for increased surface runoff and soil erosion. A key element in the construction and operation of USSIs is water, which besides domestic consumption, is also used for dust control, in building materials, and for mirror and panel washing. In arid regions, the potential stress on existing water resources and ecosystems needs to be carefully assessed. USSIs also raise concerns about impacts to sensitive, rare, threatened, and endangered vegetation or wildlife species. Biodiversity in the southwest is large, and many plants and animals in this arid area are endangered and protected by law.
In order to identify, assess, and mitigate impacts to environmental resources from USSIs, it is important to monitor, model, and analyze them over the projected lifespan of these projects. Securing an adequate, reliable water source is fundamental to the feasibility of renewable energy technologies in the desert. Water constraints in the southwest have already prevented some proposed solar-energy projects from moving forward, while others have undergone modifications to their scale, technology, and proposed water source. This has come at significant costs to project proponents while generating delays in project timelines. Greater certainty about likely impacts, and the effectiveness of mitigation measures is key to managing soil, water, air, and biological resources. It will also allow for more efficient environmental reviews of future projects, and for better anticipation of costs and mitigation requirements for developers.
AAPG Search and Discovery Article #90162©2013 Pacific Section AAPG, SPE and SEPM Joint Technical Conference, Monterey, California, April 19-25, 2013