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Molten salt keeps solar power flowing

BrightSource Energy will add molten salt storage to upcoming concentrating solar power plants, touting the benefits of solar thermal technology over low-cost solar photovoltaic technology.

BrightSource solar thermal power plants can be equipped with a two-tank molten salt storage system, as shown on the right side of this image. BrightSource Energy

By storing solar energy in molten salt, BrightSource Energy can now build one less solar power plant.

The company said today that it is adding energy storage to three planned solar projects that will supply power to utility Southern California Edison.

Instead of building seven power plants to provide about 4 million megawatt-hours per year, BrightSource now expects to be able to meet that with six concentrating solar plants to be built over the next six years, including three that will have storage. It is now constructing its first project, the Ivanpah Solar Electric Generating System, which will not have storage.

BrightSource's plants use a field of computer-controlled mirrors that concentrate sunlight onto a tower. The heat creates steam, which is used to generate electricity in a conventional turbine. The storage system keeps molten salt in tanks and produces steam as needed.

By providing power to the grid after the sun goes down, BrightSource can earn more money from its plant during peak demand times and generally lower the cost of solar, the company said.

Storage also helps give solar thermal technologies an advantage compared with solar phototoltaic panels, which have plummeted in cost over the past three years because of lower silicon prices and high-volume manufacturing in China. A number of large solar projects in the U.S. have abandoned concentrating solar thermal technologies for flat-plate solar photoltaic panels because of cost.

BrightSource said that its storage system will allow solar to replace fossil fuel plants rather than supplement them and avoid the need for natural gas back-up power. Earlier this year, California passed a law encouraging development of grid storage, which helped bring the addition of storage to BrightSource's plants, it said.

Update at 9:55 a.m. PT: The information on how many plants will have storage has been clarified.