World's longest-running solar thermal power station decommissioned in US

According to the U.S. Energy Information Administration (EIA) website, the Solar Power System (SEGS) in California’s Mojave Desert decommissioned five solar thermal power plants (SEGS 3 through 7) in July 2021, and in September 2021 Retirement of the sixth solar thermal power plant (SEGS 8). After SEGS 8 is decommissioned, only one solar thermal unit in SEGS will continue to operate (SEGS 9). SEGS began operations in 1984 and is the longest-running solar thermal power facility in the world.

The total installed 356 megawatt (MW) SEGS facility will initially consist of nine solar thermal power plants. SEGS 1 and SEGS 2 were decommissioned in 2015 and replaced by two solar photovoltaic (PV) plants, Sunray 2 and Sunray 3. From 1986 to 1988, SEGS 3 to SEGS 7 (36 MW per unit) came online. SEGS 8 and SEGS 9 (with a capacity of 88 MW) came online in 1989 and 1990, respectively.

Solar thermal power plants use mirrors to focus sunlight onto receivers, which absorb sunlight and convert it into thermal energy (heat). SEGS units are parabolic trough concentrating solar thermal power (CSP) systems in which parabolic (u-shaped) mirrors capture and concentrate sunlight, heat synthetic oil in a central tube, and then boil the water to produce steam, which drives a turbine to generate electricity.

Solar thermal power plants account for a relatively small share of U.S. utility-scale solar generation capacity. As of June 2021, utility-scale solar generation in the U.S. is approximately 52,600 MW, of which 3.3% is solar thermal power generation; the remaining 96.7% is utility-scale solar photovoltaic.

Although U.S. solar power capacity is growing rapidly, most of the capacity added in recent years has been solar photovoltaics. Between 2015 and June 2021, the U.S. grid added about 42,000 MW of utility-scale photovoltaic capacity; however, no new solar thermal capacity has been added since the Crescent Dunes power plant came online in 2015.

The U.S. plans to build a utility-scale solar thermal power plant within the next five years: the 200-megawatt La Paz Solar Tower in Arizona, according to data reported to EIA by developers and plant owners.