Southern California Edison (SCE) and BrightSource Energy have reached agreements on a series of contracts for 1,300 megawatts (MW) of solar thermal power. The agreement, which now requires approval from the California Public Utilities Commission, calls for a the development of seven projects to make up the total capacity.

The first of these solar power plants, sized at 100 MW and located in Ivanpah, California., could be operating in early 2013 and is expected to produce 286,000 megawatt-hours (MWh) of renewable electricity per year. BrightSource will build and place in commercial operation each of its plants as quickly as permitting and infrastructure allow. The full 1,300 megawatts of projects will produce 3.7 billion kilowatt-hours of clean energy.

“These contracts represent a significant addition to our renewable portfolio, which is already the nation’s largest,” said Stuart Hemphill, SCE vice president of Renewable and Alternative Power. “This innovative solar technology helps to further our position as the nation’s largest purchaser of solar energy, as well.”

BrightSource Energy will build the plants using its proprietary Luz Power Tower 550 (LPT 550) energy system. The system uses thousands of small mirrors called heliostats to re­flect sunlight onto a boiler atop a tower to produce high temperature steam.

The steam is then piped to a conventional tur­bine which generates electricity. In order to conserve precious desert water, the LPT 550 system uses air-cooling to convert the steam back into water. The water is then returned to the boiler in an environmentally-friendly closed cycle. This fully integrated energy system is designed to offer the highest operating efficiencies and lowest capital costs in the industry.