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Wednesday, 21 September 2011

Microwave ovens a key to energy production from wasted heat

Oregon State University
Sept 20, 2011

More than 60 percent of the energy produced by cars, machines, and industry around the world is lost as waste heat – an age-old problem - but researchers have found a new way to make “thermoelectric” materials for use in technology that could potentially save vast amounts of energy.

And it’s based on a device found everywhere from kitchens to dorm rooms: a microwave oven.

Chemists at Oregon State University have discovered that simple microwave energy can be used to make a very promising group of compounds called “skutterudites,” and lead to greatly improved methods of capturing wasted heat and turning it into useful electricity.

A tedious, complex and costly process to produce these materials that used to take three or four days can now be done in two minutes.

Most people are aware you’re not supposed to put metal foil into a microwave, because it will spark. But powdered metals are different, and OSU scientists are tapping into that basic phenomenon to heat materials to 1,800 degrees in just a few minutes – on purpose, and with hugely useful results.

These findings, published in Materials Research Bulletin, should speed research and ultimately provide a more commercially-useful, low-cost path to a future of thermoelectric energy.

“This is really quite fascinating,” said Mas Subramanian, the Milton Harris Professor of Materials Science at OSU. “It’s the first time we’ve ever used microwave technology to produce this class of materials.”

Thermoelectric power generation, researchers say, is a way to produce electricity from waste heat – something as basic as the hot exhaust from an automobile, or the wasted heat given off by a whirring machine. It’s been known of for decades but never really used other than in niche applications, because it’s too inefficient, costly and sometimes the materials needed are toxic. NASA has used some expensive and high-tech thermoelectric generators to produce electricity in outer space.
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