Researchers at the Massachusetts Institute of Technology (MIT), United States, have developed an unusual, high performance way of turning the sun’s heat into electricity. The new system produces power with an efficiency that is about eight times higher than ever previously reported for a solar thermoelectric device, and does so by generating and harnessing a temperature difference of about 200 degrees Celsius between the interior of the device and the ambient air. The MIT solar thermoelectric generators are made through a nanostructured process, and have no moving parts, unlike other such systems that typically involve vast arrays of movable mirrors that track the sun and focus its rays on a small area. The generator is, instead, placed inside a vacuum chamber made of glass, and covered with a black plate of copper that absorbs sunlight, but does not re-radiate it as heat. The other side is in contact with ambient temperatures and, when placed in the sun, the entire unit heats up, even if it is not directly facing the sun. The unit requires much less material than conventional photovoltaic panels, so it could be much less expensive to produce. Gang Chen, MIT’s Carl Richard Soderberg Professor in Power Engineering and director of the Pappalardo Micro and Nano Engineering Laboratories, and a co-author of the paper published in the journal Nature Materials, said the concept “is very radical.” Chen said the new system won’t be a substitute for solar photovoltaics, but does offer another way of tapping into solar energy. It can also be easily piggybacked onto the existing solar hot-water industry, with “no subsidies required,” Chen said. “It can be a game-changing thing.”
http://web.mit.edu/newsoffice/2011/flat-solar-thermal-0502.html