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One step closer to a new kind of thermoelectric 'heat engine'

12 July 2012

Researchers studying a new magnetic effect that converts heat to electricity have discovered how to amplify it a thousand times over - a first step in making the technology more practical. In the so-called spin Seebeck effect, the spin of electrons creates a current in magnetic materials, which is detected as a voltage in an adjacent metal. 

An artist's rendering of the giant spin-Seebeck effect

Ohio State University researchers have determined how to create a similar effect in a non-magnetic semiconductor while producing more electrical power. 

They've named the amplified effect the 'giant spin-Seebeck' effect, and the university will licence patent-pending variations of the technology. The resulting voltages are admittedly tiny, but in this week's issue of the journal Nature, the researchers report boosting the amount of voltage produced per degree of temperature change inside the semiconductor from a few microvolts to a few millivolts - a 1,000-fold increase in voltage, producing a 1-million-fold increase in power.

Joseph Heremans, Ohio Eminent Scholar in nanotechnology, said that his team's ultimate goal is a low-cost and efficient solid-state engine that coverts heat to electricity. These engines would have no moving parts, would not wear out, and would be infinitely reliable, he added.

"It's really a new generation of heat engine," said Heremans, professor of mechanical engineering and professor of physics at Ohio State. "In the 1700s we had steam engines, in the 1800s we had gas engines, in the 1900s we had the first thermoelectric materials, and now we're doing the same thing with magnetics."

This research could enable electronic devices that recycle some of their own waste heat into electricity. In a computer, it could enable heat-powered computation, or, inversely, it could provide cooling.


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