How an engine's exhaust can generate electricity

Car exhaust could be used to generate electricity, which would reduce fuel consumption.

We waste so much energy. As much as 60 percent of energy is wasted as heat. Our laptops, nuclear power plants, chemical factories and cars all contribute to this waste heat.

Researchers at Purdue University are working with General Motors to create thermoelectric generators (TEGs) to turn waste heat directly into electrical energy for cars. The idea is to use the heat from the car engine's exhaust to generate electricity.

The prototype - which is a small metal chip - will basically hook up to the exhaust system and tap into heat coming from the gases.

The technology used today can't hold up against the high temperatures inside catalytic converters.

But the material the researchers want to use is called skutterudite, which is a mix of minerals. Then other rare metals are added to it to make sure it's a poor conductor. That way, the current is generated when the material is hot on one side and cold on the other.

Ideally, it would reduce the amount of fuel used by five percent. It does this as it generates electricity to help power the car's electrical system and charge its battery.

The applications of the technology go beyond car exhaust. It could generate electricity in homes and power plants from waste streams. Waste byproducts could supply 19 percent of U.S. power, the heat sure gets lost easily. The promise is there, but the technical hurdles remain.

Photo: Mark Simons/ Purdue University

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