Chile’s government has agreed to the creation of an enormous solar thermal plant. Besides the size, what is particularly ambitious is the hope that this plant will generate electricity 24 hours a day, seven days a week.
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.
Because the molten salt will stay hot for hours in its thermal storage tank—even throughout the night or during a cloudy morning—the molten salt is said to store that thermal energy. Each tower will have 13 hours of energy storage, for a total of 5.8 gigawatt-hours of energy storage capacity.
In total, the proposed Tamarugal plant would be able to provide 450 MW of power continuously, 24 hours a day. The plant could theoretically generate 2,600 GWh annually.
The company SolarReserve, based in the United States, is also pushing for two more projects in Chile, one of which is ready to be built if the project is green-lit by the government. You can see some renderings of what they hope the plant will look like upon completion here. Solar energy and other renewable energy are quickly replacing coal energy, regardless of what Mitch McConnell and Donald Trump tell you.