March 20, 2008

Thermoelectric materials: making electric current from heat

We make electricity from heat all the time. Burn fuel, the heat moves the piston, the piston turns the generator, and we can plug in our X-Box or our vacuum cleaner. But imagine if we could heat a wire and make electric current move through the wire just by heating it.

Thermoelectric materials are capable of absorbing heat and turning it into electric current. Today's thermoelectric materials aren't very efficient, but they are used in niche applications like in cooling certain microchips. NASA uses them on spacecraft that are too far from the sun to use solar power.

Recently, researchers at MIT and Boston College have discovered a simple way of making thermoelectric materials, and these theromelectric materials are 40 percent more efficient than normal. The process involves grinding bismuth antimony telluride into fine particles and then pressing it back together. link

If thermoelectric materials can someday be easily made in bulk, these matrials could be used to make engines or air conditioners significantly more energy efficient. A typical car engine loses roughly a third of it's energy to heat. Thermolelectric materials could someday cool the engine of a hybrid car, and take a good portion of the lost energy to power the electric drive motor. Such a vehicle would be super efficient. Another possiblity is using thermoelectric materials absorb heat from the air-- a much more efficient way of cooling a building. link

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