As the world tries to combat climate change, sustainable forms of energy are on the rise. Solar energy is of particular interest, but arrays of photovoltaic panels take up a lot of space and can compete for prime food-producing land. Now researchers, reporting in ACS' journal Environmental Science & Technology, have found plenty of places to install solar devices without taking up arable land, while generating enough power to help regions meet their energy goals.

Previous studies have shown that solar installations are often built on natural areas or croplands, a practice that takes that land away from conservation efforts or agriculture. For example, one study based in Leece, Italy, reported that 51 percent of the area's solar devices were located on untouched and agricultural land, including century-old olive groves. In the current study, Rebecca R. Hernandez, Michael F. Allen and Madison K. Hoffacker wanted to explore how solar efforts can expand without encroaching on valuable natural and arable land.

The researchers evaluated four alternative types of installation sites that avoid farmable land, using California's Central Valley as a case study. The sites are those in which solar panels were installed on rooftops and building walls in the region's cities; lands that are too salty for crops; contaminated lands such as brownfields and superfund sites; and water reservoirs. The researchers identified the Valley's unconventional sites and calculated how much energy solar panels in these locations could generate. They found that alternative surfaces totaling more than 1.5 million football fields in size could accommodate solar installations in the region and generate more than 19,000 terawatt-hours of energy per year without impinging on farmlands or protected areas. All totaled, this level of production exceeds California's projected electricity demand of 321 terawatt-hours projected for 2025.

The authors acknowledge funding from the University of California at Riverside, Stanford University, the Audubon California, the Agricultural Experiment Station Hatch Project, the California Energy Commission and the Department of Land, Air and Water Resources at University of California, Davis.