This is an excerpt from EERE Network News, a weekly electronic newsletter.

March 31, 2004

Arizona Utility Builds a 1-Megawatt Solar Trough Plant

Photo of the Solar Electric Generating Station.

The SEGS solar trough plant in California.
Credit: Kramer Junction Company

APS, Arizona's largest utility, broke ground on March 24th on Arizona's first commercial solar trough power plant. Solar troughs concentrate the sun's heat using trough-shaped parabolic mirrors that swivel on their axis to point at the sun. A pipe carrying oil runs through the focus of each solar trough to collect the heat, and the hot oil is then used to vaporize a liquid. The hot vapor is routed through a turbine, and the spinning turbine turns a generator to produce power. The new APS solar trough plant will be built at the company's Saguaro Power Plant near Red Rock, about 30 miles north of Tucson, and will generate up to 1 megawatt of power. The company expects the plant to begin producing power in April 2005. See the APS press release.

Currently, only nine solar trough plants exist in the United States, and all are located in California's Mojave Desert. The nine plants are known as the Solar Energy Generating Station (SEGS), units I through IX, and are currently owned and operated by several companies. SEGS I began producing power in 1985, and the newest unit, SEGS IX, went online in 1991. They have a combined capacity of 354 megawatts. See the "Projects Deployed" section of DOE's TroughNet Web site.