24 Hour Solar Power Gets An MIT Twist

Researchers at MIT say they’ve come up with a concentrated solar power (CSP) system that might be able to produce power around the clock. Which sounds pretty nifty, but also leads one to wonder: Have they heard about the Gemasolar plant in Fuentes de Andalucía, Spain?

As we reported last month, that Torresol-developed plant combined a “power tower” system – consisting of 2,650 mirrors bouncing sunlight to the top of a 140-meter tower at the center of the circle of mirrors – with a super-efficient receiver that absorbs 95 percent of the radiation aimed at it, to heat molten salts inside the tower to more than 500 degrees Celsius. The hot molten salts were then stored for use when the sun went down – and Gemasolar, pictured below, churned out power for 24 straight hours.

concentrating solar power, around the clock production

image via Torresol

Does this mean the MIT crew is late to the game with their 24/7 idea? Maybe, but maybe not. Their system differs from the Gemasolar CSP setup in that there’s no tower. Instead, they envision an array of reflectors on a gentle slope, aiming solar radiation at a single tank below that combines heating and storage. Use of that single tank avoids the costly – in energy and money – necessity of pumping around molten salt and heat.

MIT’s Alexander Slocum is behind this brainstorm, which he calls “CSPonD,” for concentrated solar on demand. Not only would his system be more efficient than the tower configuration, he said, but because the heat-absorbing receiver wouldn’t cool down too much at night, the system would not have to go to expensive lengths to avoid the metal fatigue and failure that is a typically a big concern with CSP.

MIT Solar

image via MIT

MIT did some tests out on hillsides in White Sands, N.M., and China Lake, Calif., and got encouraging results. Next step is larger tests needed to refine the design. And then, Slocum said, “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.'”

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.