The California desert will bloom again, this time with large solar power plants.

BrightSource Energy has inked a deal with Southern California Edison (SCE) to sell electricity from seven solar power plants that will have a total capacity of 1.3 gigawatts. SCE and BrightSource call the agreement the largest solar deal in the world.

BrightSource, based in Oakland, Calif., is developing a technology that uses the sun's heat, rather than light, to produce electricity. Instead of solar panels that can be seen on some rooftops today, BrightSource's equipment consists of thousands of mirrors called heliostats that redirect the sunlight to a boiler on top of a central tower to produce steam. The steam then goes to a generator to produce power.

This approach, called solar thermal, is finding fans among utilities interested in getting lots of power from a centralized source. Solar thermal power plants require lots of land and are typically located in isolated areas with lots of bright sun. California, Arizona and Nevada have attracted many solar thermal project developers from within the United States and Europe (see Abengoa Q&A: Heating Up the Solar-Thermal Market).

An example of an alternative approach would be to place conventional solar panels on the rooftops of businesses, homes and government buildings across a city or region. SCE is carrying out such a project, which involves placing 250 megawatts worth of panels on commercial rooftops.

BrightSource plans to build the first, 100-megawatt power plant for SCE in the Mojave Desert town of Ivanpah, Calif., on land already chosen by BrightSource to build a 300-megawatt power plant for Pacific Gas and Electric (PG&E). Both the SCE and PG&E will purchase electricity from these power plants, which will be owned and operated by BrightSource.

All of these companies are moving through the permitting process to get approval from the California Energy Commission. Approval and construction could begin in early 2010, said Keely Wachs, a spokesman for BrightSource. The company could start building the PG&E project first, and begin construction of the SCE project six to nine months later, Wachs said.

It typically takes about two years to build a 100-megawatt power plant, and the SCE project could come online in 2013. BrightSource expects to complete the rest of the power projects within six to seven years, Wachs said.

The Ivanpah site wouldn't be large enough to accommodate the other, 1.8 gigawatts worth of power plants that BrightSource plans to build to sell power to SCE and PG&E. BrightSource's deal with PG&E, announced last April, calls for supplying power from up to 900 megawatts worth of power plants.

BrightSource is considering other locations in the California Mojave Desert, as well as in Mormon Mesa in Nevada to build those additional power plants, Wachs said. Overall, BrightSource is looking at developing land that can accommodate 4.2 gigawatts worth of solar projects.

The deal with BrightSource isn't the first solar-thermal project for SCE. The utility announced last June that it intended to buy power from 245 megawatts worth of power plans to be built and operated by ESolar, a startup company in Pasadena, Calif. (see California to Get More Solar-Thermal).

Wachs declined to disclose the costs of building all these power plants. BrightSource will be looking for money to build these projects, Wachs said. The company raised over $160 million in Series C last year.

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