MIT team plays with fire to create cheap energy

“Concentrating solar power,” as this type of system is called, is seeing a boom. At least 4,500 megawatts of capacity is in the development pipeline, according to the Solar Electric Industries Association in Washington. That power is about 13 to 20 cents per kilowatt – cheap enough to compete with peak power prices of fossil fuel plants – but not yet off-peak regular prices.

The goal is to bring the price down. Many older and current systems are very complex, involving a host of motors to keep dozens or hundreds of carefully polished mirrors focused on the sun. So the team focused instead on making a dish that only requires a simple electronic system to keep it aimed at the sun – and pump water into the collector coil to be heated into steam. The MIT team says their unit will produce steam heat for less than the cost of heat from oil or natural gas.

The steam is “low temperature” – about 212 to 400 degrees F. – not high temperature steam generally used to power electric turbines in conventional power plants – which can surpass 700 degrees F. Still, this “process heat” can be used cost effectively in manufacturing, food pasteurization, and heating buildings.

Making good ideas better
Part of the genius here may also be all about knowing where to look for technology. The MIT students, for instance, did not take a go-it-alone approach. As part of his “Energy Ventures” class, MIT lecturer David Pelly was hunting for some of the best new energy ideas that needed development and marketing – and discovered Doug Wood’s solar dish.

An inventor who lives on Fox Island off the coast of Washington State, Mr. Wood’s backyard is filled with all manner of solar dishes he has built – but most are enormous, he says. After working with the MIT team, they settled on a dish that is just 12 feet across.

“Our big discovery was that small worked better, cheaper, than any of our huge old models,” Wood says. “Getting the size right was the critical breakthrough.”
This summer, the team plans to relocate its fledgling company to the San Francisco area in order to find funding, as well as to tap the burgeoning solar-power expertise in the region.

Fortunately for traffic and pedestrians here at MIT, the Raw Solar dish is unlikely to be of any use as a laser-style device. When lowered toward street level the beam deflects.

“Yes, I know it probably looks like a ray that could fry Boston,” Ritter says. “But it actually loses power very quickly beyond the focal point, so there’s no actual danger. You can’t accidentally step into the focal point. Nobody walking along the sidewalk will get toasted.”

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