Making electricity from wasted energy

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Researchers at the Massachusetts Institute of Technology found the way to harvest much of the wasted heat produced by everything from computer processor chips to car engines to electric power plants, and turn it into usable electricity, Journal of Applied Physics reported.

"More than half of the energy consumed worldwide is wasted, most of it in the form of excess heat. This new technology would allow conversion of waste heat into

electricity with an efficiency several times greater than existing devices," says senior author Peter Hagelstein.

Hagelstein said, "That kind of waste-energy harvesting might, for example, lead to cellphones with double the talk time, laptop computers that can operate twice as long before needing to be plugged in, or power plants that put out more electricity for a given amount of fuel".

"Theory says that conversion of heat into electricity can never exceed a specific value called the Carnot Limit, but current commercial thermoelectric devices only achieve about one-tenth of that limit," he said.

The author added, "The calculations show that this new kind of system could ultimately reach as much as 90 per cent of that ceiling".

By controlling all aspects of the device, they hoped to better understand how to design the ideal thermal-to-electric converter.