A few minutes later, the real demonstration begins. A pole protrudes from the front of the solar dish – similar to the rod that sticks out from satellite-TV dishes. Wrapped around the end of it is spiral tubing, which the team fills with water from a garden hose. With the dish swiveled to face the sun, the tubing glows white. Boiling water sputters from the far end of the hose, which lies in the shade beneath the dish.
The secret: frugal design
Materials and construction are fairly simple. Aluminum tubing is riveted to a steel cross bracing. Affixed to that frame are strips of mirror from a local supply house. High-heat barbecue paint coats the coil collector at the apex of the pole.
“Small solar thermal is a kind of power that has really been traveling under the radar,” says Micah Sze, an MIT business school graduate tapped to help market the technology. “People have been focusing on electricity from the sun, not the heat market. We think there’s an opportunity to supply heat to large institutions like universities and someday individual homes.”
“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.