Nevada and Sicily Look to Molten Salt for Solar Storage

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http://www.dailytech.com/Nevada+and+Sicily+Look+to+Molten+Salt+for+Solar+Storage/article19212.htm

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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.

The use of molten salt in solar thermal plants has been done before – Alcazar de San Juan, Spain obtained a molten salt plant in November 2009. Also, in 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, a Los Angeles-based solar thermal company, 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.

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 recycled back into the system where it will be reheated and used once again to create steam, 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. The U.S. state received approval for this project by the Public Utilities Commission of Nevada on Thursday. In addition, SolarReserve's subsidiary, Tonopah Solar Energy, signed a power of purchase agreement with Nevada Energy that will last 25 years and will provide energy from the plant.

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