Physics changes heat directly to electricity
Researchers have invented a new material that will make cars even
more efficient by converting heat wasted through engine exhaust into
electricity.
Science reported the same technology could work in power
generators and heat pumps, said project leader Joseph Heremans, Ohio
Eminent Scholar in Nanotechnology at Ohio State University.
Scientists call such materials thermoelectric materials, and they
rate the materials’ efficiency based on how much heat they can convert
into electricity at a given temperature.
Previously, the most efficient material used commercially in
thermoelectric power generators was an alloy called sodium-doped lead
telluride, which had a rating of 0.71. The new material, thallium-doped
lead telluride, has a rating of 1.5—more than twice that of the
previous leader.
What’s more important to Heremans is the new material is most
effective between 450 and 950°F—a typical temperature range for power
systems such as automobile engines.
Some experts argue only about 25% of the energy produced by a
typical gasoline engine moves a car or powers its accessories, and
nearly 60% is lost through waste heat, which escapes in engine exhaust.
A thermoelectric device can capture some of that waste heat.
“The material does all the work. It produces electrical power just
like conventional steam engines, gas, or diesel engines that are
coupled to electrical generators, but it uses electrons as the working
fluids instead of water or gases, and makes electricity directly,â€
Heremans said.
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