Recently, the Solana solar power plant in Gila Bend, Arizona began commercial operation. At 280 megawatts capacity, it is the largest concentrating solar power or CSP plant in the world, using parabolic trough mirrors to focus the rays of the sun. But it has another notable feature as well: it keeps generating electricity long after the sun goes down.
The Solana plant is the first solar plant in the United States to use thermal energy storage in the form of a molten salt system. Some of the heat collected from the solar mirrors is absorbed by a mixture of molten salts such as various nitrates, which are commonly used as heat-transport fluids in the chemical and metals industries. The heated molten salt is then stored in an insulated tank.
CSP plants use heat generated by the sun to boil water, and the steam produced operates conventional turbines to generate electricity. At the new Solana plant, when the sun sets or is otherwise no longer heating the water, the hot molten salt is pumped into the steam generator and electricity generation continues. In this way, the plant can generate electricity for about six hours after the sun has set.
A major challenge facing both solar and wind power is that they are only intermittent sources of energy. With its molten salt system, the new Solana solar power plant is able to stretch out the operating cycle of the plant and increase the reliability and predictability of solar power.
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Web Links
Abengoa’s Gigantic ‘Salt Battery’ Stores Utility-Scale Solar Energy
http://www.triplepundit.com/2013/10/arizona-solar-power-sector-leaps-into-us-lead-with-new-plant/
Photo, taken on May 13, 2009, courtesy of Alex Lang via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.