The EPA, through its Repowering America's Lands initiative, has been diligently cataloguing parcels of land that are damaged, contaminated, or otherwise without much ecological value, but potentially suitable for renewable energy development. With help from the National Renewable Energy Laboratory (NREL), they've put their California sites database into map form as the just-launched Renewable Energy Siting Tool, with 11,000-plus sites listed in a map layer viewable with Google Earth.
Among the thousands of sites, some as small as an acre or two of urban vacant lot, are 75 places the EPA has determined to be "high priority" sites for development of utility-scale renewable energy including 21 for geothermal development.