While solar panels can use stored energy from the day to provide power at night, and solar power is absorbed by higher-end solar panels even when it is cloudy, the panels still work best when the sun is shining its brightest. The solution to a steady supply of solar power even on cloudy days and at nighttime might come in the form of molten salt, which is an excellent conductor of heat.
Last week the Department of Energy offered a $737 million loan guarantee to the Crescent Dunes Solar Energy Project in Nevada. The project includes a 640-foot tall solar power structure and a molten salt-based collection and storage system. The system will capture and focus the sun’s thermal energy by using as many as 17,500 heliostats, which are very focused mirrors. The power plant will aim the heliostats at a focal point in a tower, which will heat up salt to 1,050 degrees Fahrenheit. The salt will be pumped near water to create steam that will run a turbine. The molten salt storage system allows the sun’s thermal energy to be stored for up to ten hours, permitting steady, uninterrupted power despite cloud cover and the disappearance of the sun at night. This method would reduce the need for carbon pollution emitting generators, which currently supplement renewable generation technologies during periods of no or low solar resource.
Once complete, the plant is expected to produce about 500,000 megawatts annually, which is enough to power 43,000 homes and cancel out about 20 per cent of the emissions of a coal power plant. The Crescent Dunes Solar Energy Project, sponsored by SolarReserve, LLC, will be the first of its kind in the United States and the tallest molten salt tower in the world. So far it’s just a proof of concept, but if it works as effectively as claimed, towers full of molten salt might start dotting the horizon, which just might cause as many complaints as wind turbines do.