The U.S. government plans to boost the development of geothermal energy systems in Western states, with the aim of having 10 percent of the West’s electricity generated by the earth’s heat within 20 years, Energy Secretary Bill Richardson announced yesterday. Richardson detailed 21 partnerships between private industry and the Department of Energy to fund geothermal energy production, many of them in Nevada, which geologists say has the highest geothermal potential of any state in the nation. Geothermal power — considered to be renewable — is derived by circulating water deep into the earth where heat turns it into steam and vapor that are then used to produce electricity.