When the Sun Don't Shine and the Wind Don't Blow
Posted by Jim Gunshinan on January 08, 2010
I add a little salt to the water when cooking spaghetti—it raises the boiling point so that you can cook the pasta more quickly, although I’m not sure it makes a big difference. Mostly I add salt to make the spaghetti taste better. The properties of a liquid salt—a mixture of sodium nitrate and potassium nitrate—are a little different. This liquid salt will store heat up to a temperature of 1,0000F, which is much higher than the boiling point of water, 2120F at sea level. The Pacific Gas and Electric Company, (PG&E) has contracted with SolarReserve LLC to store energy using liquid salt. The Rice Solar Energy Project will produce enough electricity to meet the demand of 60,000 households—about 150 megawatts—beginning in 2013.
The Rice Project uses a large circular field of mirrors to reflect light onto a central tower. Liquid salt is circulated through the tower and, once heated, it is stored in an insulated tank. When the sun goes down the liquid salt will still be able to heat water well past the boiling point to create steam, which can be fed into a conventional steam turbine to produce—Walla—electricity. The liquid salt, now cooled, is stored in another tank and is ready to begin the process all over again.
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