The massive Ivanpah Solar Electric Generating Station in California will be turned on soon. It will be the biggest solar thermal plant ever, generating power for 140,000 homes, with nearly 200,000 mirrors on 3,500 acres.
Solar thermal reflects the heat of the sun from heliostatic mirrors to a central tower to power steam turbines. Ivanpah says they use air to create steam, not water, and reuse water in turbines, making their water use comparable to solar PV, which is for cleaning only.