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| MIT sheds new light on old solar PV approach  Massachusetts Institute of Technology, MIT, researchers are trying to unleash the promise of an old idea by converting light into electricity more efficiently than ever before. The research is applying new materials, new technologies and new ideas to radically improve an old concept - thermophotovoltaic, TPV, conversion of light into electricity. Rather than using the engine to turn a generator or alternator in a car, for example, the new TPV system would burn a little fuel to create super-bright light. Efficient photodiodes which are similar to solar cells would then harvest the energy and send the electricity off to run the various lighting, electrical and electronic systems in the car.Such a light-based system would not replace the car's engine. Instead it would supply enough electricity to run subsystems, consuming far less fuel than is needed to keep a heavy, multi-cylinder engine running, even at low speed. Also, the TPV system would have no moving parts; no cams, no bearings, no spinning shafts, so no energy would be spent just to keep an engine turning over, even at idle. At the heart of their energy system would be a cylindrical element, such as tungsten, etched with tiny pits - nano-holes - so it emits intense light at selected wavelengths when heated to a high temperature, perhaps 2,200ºF. Special light-sensing cells, made of a new material such as gallium-antimonide, would surround the glowing element, picking up the radiated light. A highly specialized filter, set between the two, would let the most useful light wavelengths pass through to hit the photodiodes, while reflecting light of less useful wavelengths back to the heating element, pumping up the temperature. The relatively high efficiency is expected to come from scientists' new ability to fine-tune all three main parts of this system. This includes the light emitter, the cells that respond well to that tuned light, and a way to scavenge light at wavelengths that might otherwise be wasted. In addition, new TPV systems might mesh nicely with hybrid automobile technology, in which fuel is saved by shutting down the engine when the car is stopped, say at traffic signals. In the future, conventional cars may operate the same way. Providing electricity and air conditioning with the engine off will be a necessity. Such a system, once commercialized, might also be applied to other problems, such as supplying the power to run large semi trucks' lighting, air conditioning and electronic systems, eliminating the need to run the diesel engine all night long while the driver rests. TPV-generated power might also be ideal for uses in remote places, distant from power lines, similar to what is being done now with solar collectors and fuel cells. write your comments about the article :: © 2006 Construction News :: home page |