The Department of Energy just invested $737 million into the Crescent Dunes Solar Energy Project in Nevada, which will generate energy well into the night by using molten salt as an energy storage medium. To do this the plant will focus nearly 20,000 heliostats upon a solar power tower filled with salt, heating the material to 1,050 degrees Fahrenheit. Once it has been heated the salt will retain its thermal energy for a long time, and it can be mixed with water to produce steam on demand, which can be used to drive turbines to produce electricity.
Nevada’s new molten salt solar plant will be run by rocket scientists from Pratt and Whitney. Companies such as SolarReserve have championed the use of molten salt in solar thermal projects because unlike water, it retains heat for a very long time. In this case, it is hoped that the plant will continue to produce power for 12 hours after the sun has set. The National Solar Thermal Test Facility has conducted several studies and concluded that molten salt is the most efficient material when it comes to storing the sun’s heat.
In the report, it was stated that, “molten salt is used in solar power tower systems because it is liquid at atmosphere pressure, it provides an efficient, low-cost medium in which to store thermal energy, its operating temperatures are compatible with today’s high-pressure and high-temperature steam turbines, and it is non-flammable and nontoxic.” Another benefit of salt is that it is very widely available as a natural resource, therefore costs are cheaper too.