This is an excerpt from EERE Network News, a weekly electronic newsletter.
Arizona Completes a One-Megawatt Solar Trough Plant
Arizona Public Service Company (APS) commemorated Arizona's first solar trough power plant on Earth Day, April 22nd. The one-megawatt plant features more than 100,000 square feet of trough-shaped mirrors, and is the first solar trough plant built in the United States in 17 years. Located between Phoenix and Tucson, the plant consists of six rows of mirrors, each more than 1,200 feet long. The mirrors concentrate the sun's energy to heat oil, which is then used to vaporize an organic fluid. The vapor spins a turbine to drive a generator, producing power, and the vapor is then condensed and reused.
Although existing solar trough systems boil water rather than an organic fluid, the organic fluid vaporizes at a lower temperature than water, allowing the plant to produce more power at lower temperature. Such organic-fluid power conversion systems are typically employed in geothermal and biomass power plants. The APS system also allows for hot oil storage, which will help the plant match its power output to the utility's needs. Solargenix Energy LLC provided the solar troughs for the APS plant, while Ormat International designed and installed the power conversion system.
The APS plant is the vanguard for a resurgence of solar trough plants in the United States. Solargenix is currently building a 64-megawatt plant in Boulder City, Nevada, that will be the largest solar trough plant in the world when it is completed next year, while other large solar trough plants have been proposed in California. See the APS press release.