Large mirror arrays that concentrate light on a tank have been made before, but now a team at the MIT has designed a system that simplifies what has been done before and also makes it cheap for concentrated solar power to enter our homes, rivaling the price of coal.
So far, concentrated solar power systems relied on mirrors circling a tower, all of them focused on a tank containing molten salts. This approach is a bit expensive and hard to implement, so the MIT scientists thought of reformulating the scheme by placing the mirrors on a lightly-sloped hill and the tank accumulating the heat at the base of the hill, on the ground, just like in the picture.
The concentrated sunlight would hit the insulated tank and transfer the heat to a narrow opening at its top. The tank would feature a movable separator inside, that would lower its position when hot molten salts would go up, leaving the colder salt at the bottom.
The heat would then get transferred on demand through pipes surrounding the tank. The pipes would contain water, create steam, and finally drive a turbine that would generate electricity.
Feasibility studies have also been made by the researchers. A complete concentrated solar system could generate electricity at rates from 7 to 33 cents per kilowatt-hour, thus competing with other conventional sources of energy. They hope to make a demonstration of a system that could generate up to 200 kW.
The team analyzed two potential sites for CSPonD on hillsides near White Sands, N.M., and China Lake, Calif. By beaming concentrated sunlight toward large tanks of sodium-potassium nitrate salt  each measuring 25 meters across and five meters deep  two installations could each provide 20 megawatts of electricity 24/7, which is enough to supply about 20,000 homes. The systems could store enough heat, accumulated over 10 sunny days, to continue generating power through one full cloudy day.
“It’s going to take a company with long-term vision to say, ‘Let’s try something really different and fundamentally simple that really could make a difference,'” says Alexander Slocum, the man behind the idea. Time will tell.
