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Thermoelectric energy regeneration sounds like a complicated topic, but it's really pretty straightforward: recapturing energy that would otherwise be wasted as heat and using it to power something. In the case of GM and Purdue University, that something is a car's electrical system. The benefits? Reduced load on the engine, improving fuel economy.

The system itself is a thermoelectric generator, or TEG, installed in the exhaust, downstream from the catalytic converter. The heat in the exhaust gases is used to generate electricity that then powers the car's electrical systems--audio, climate control, etc.--reducing the load on the alternator, and, thereby, the total load on the engine. As much as 70 percent of the energy in burned fuel is wasted as heat, so recovering some of this essentially "free" waste energy is a way to improve efficiency for any combustion engine, including those in hybrids or EREVs like the Chevy Volt.

If all of this sounds familiar, it should: BMW previewed a similar exhaust-based system in 2009. GM and Purdue's project, beginning on January 1, 2011, aims to cut fuel use by five percent with its first prototype, with a goal of ten percent savings with more capable thermoelectric generator materials.

Like BMW's previewed system, the GM-Purdue solution uses what is essentially a Peltier effect to create voltage across a pair of electrodes through temperature gradients--the difference in temperature from one side of the system to the other, the greater the voltage. To progress toward the project's 10 percent goal, more exotic materials could be used, but ideally, something mass-producible is the goal, so scientists are looking at ways to use less expensive, more common materials.

The project will cover three years of research with $1.4 million in funding from a National Science Foundation and U.S. Department of Energy grant.  

[Purdue University]