In the often cloudless American Southwest, the sun pours more than eight kilowatt-hours* per square meter of its energy onto the landscape. Vast parabolic mirrors in the heart of California's Mojave Desert concentrate this solar energy to heat special oil to around 750 degrees Fahrenheit (400 degrees Celsius). This hot oil transfers its heat to water, vaporizing it, and then that steam turns a turbine to produce electricity. All told, nine such mirror fields, known as concentrating solar power plants, supply 350 megawatts of electricity yearly.
Scientific American September 19, 2007