Following its decision to shrink the area of the future solar arrays in a California desert and their capacity to address some of the environmental concerns that had been raised in the past, Bright Source Energy secured an agreement by the US Department of Energy to guarantee more than $1.37 billion in loans to finance the solar thermal project expected to nearly double the nation's entire existing solar energy generation capacity.

Most of the nearly 400 MW the Ivanpah project is expected to generate will be purchased by PG&E;, a major northern California utility that supplies power to San Francisco, much of the Silicon Valley and the large number of data centers located in the region. Bright Source already has contracts with PG&E; to sell about two-thirds of the electricity generated by the future Mojave Desert solar plants.

Another large utility in the state, Southern California Edison, will purchase about one-third. Bright Source has contracted to sell a total of 2,600 MW of power to the two energy companies cumulatively.

Thousands of mirrors in a Bright Source system concentrate and direct sunlight to a boiler, where water is heated to 550 degrees Celsius

The project consists of three solar thermal plants in California's southeast. Solar thermal plants use solar energy to heat water to produce steam used by standard turbines to generate electricity. Bright Source's competitors in the solar thermal space include Lakewood, Colo.-based Abengoa Solar and Pasadena, Calif.-based eSolar.

Some environmental protection groups voiced concerns that the arrays would be damaging to some of the desert's species. In response, the company altered its plan by reducing the project's size by 12 percent "in an effort to trim the number of desert tortoises that must be relocated and to avoid an area of rare plants," the New York Times reported.

The adjustment reduced the project's generation capacity from 440 MW to 390 MW.

The project is still undergoing review by state and federal agencies and DoE backing is dependent upon its success in securing all the necessary permits. Bright Source plans to start construction in the second half of 2010.