The Chilean government recently gave the go-ahead on a massive solar thermal plant that is expected to produce electricity 24 hours a day, seven days a week—a considerable feat for a plant that depends solely on solar energy. The plant, proposed for a site in Chile’s Tamarugal province, would consist of three 150 megawatt solar thermal towers, which become heated as mirrors placed around each tower reflect sunlight onto it.
That heat is transferred to molten salt, which circulates through the plant during the day and is stored in tanks at night. The salt, a mixture of sodium nitrate and potassium nitrate that’s kept at a balmy 1,050 degrees Fahrenheit (566 degrees Celsius), is used as a “heat transfer fluid.” As energy is needed, the salt can be dispatched to a heat exchanger, where it will lend its heat to water to create a super-heated steam. That steam is used to move a traditional steam turbine to create electricity.
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