MOLTEN SALTS IN THE SUN

Nevada and Sicily Look to Molten Salt for Solar Storage; Solar power, available 24-7? It sounds too good to be true, but some believe it can be done efficiently
Tiffany Kaiser, August 1, 2010 (Daily Tech)

"As a new way to store and release solar energy, U.S. state Nevada and Sicily, Italy will both use molten salt to operate solar thermal plants…Alcazar de San Juan, Spain obtained a molten salt plant in November 2009…[I]n May of this year, the U.S. Department of Energy gave 13 companies $62 million for the development of thermal solar technology, and a few of them are considering the use of molten salt.

"SolarReserve…developed the technology to make this system possible. Large heliostats will be used in the two separate plants in order to reflect sunlight onto pipes that carry a molten salt liquid, which has potassium and sodium nitrates in it. The liquid salt then absorbs the heat from the sunlight in order to make high-pressure steam, which powers the turbine and produces electricity."

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"What makes this technology useful above and beyond other solar thermal plants is that the molten salt holds the heat it absorbs up to 24 sunless hours, which means the plant can use it's heat for an extended amount of time increasing operation hours. Once the molten salt has cooled, it [is] recycled back into the system…restarting the process all over again.

"Nevada's plant, the Crescent Dunes Solar Energy Project, will be a 100-megawatt plant and is expected to generate 480,000 megawatt hours of electricity annually…[It was just approved] by the Public Utilities Commission of Nevada…[and] SolarReserve's subsidiary, Tonopah Solar Energy, signed a power of purchase agreement with Nevada Energy that will last 25 years…The plant is expected to create 450 construction jobs, 45 permanent jobs for plant operation and 4,000 indirect jobs for local service providers and suppliers [when completed]…"

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"…Sicily's solar thermal plant, named Archimedes, has already opened…[T]he European energy company Enel [operates the]…5-megawatt plant.

"While both solar thermal plants will use molten salt to power them, Sicily's plant will not work on molten salt alone. The liquid salt will work in "conjunction" with [an existing] gas-powered electricity plant…The molten salt will produce the steam…power turbines in the gas plant and… use gas as a supplement…"