GM, not content to rest on the laurels of its highly rated new Chevy Volt electric/gasoline car, is working with researchers at Purdue University to develop thermoelectric generators that can harvest the waste heat from a car’s exhaust and turn it into electricity. The initial goal is to reduce fuel consumption by 5%, and once some kinks are worked out a savings of 10% is possible.
Thermoelectric Generators and Car Exhaust
The new generator would save gas by using scavenged energy to charge the battery and keep the car’s electrical systems running. The researchers have developed a prototype that sits behind the catalytic converter. A more efficient design would be to fit the generator inside the converter, but the device is not yet engineered to withstand the high temperatures within catalytic converters.
Thermoelectric Generators – How They Work
The principle behind thermoelectric generators is simple enough: the devices are made of materials that generate electricity through a difference in temperatures, a phenomenon known as the Seebeck effect. The car exhaust will heat the side of the thermoelectric generator that faces the hot gasses, while the other side remains relatively cool. Purdue research team leader Xianfan Xu explains that the trick is to keep the heat from flowing too rapidly from one side to the other, while grabbing the maximum amount of heat from the exhaust.
A Hearty Stew of Thermoelectric Materials
At GM, researchers are focusing on generators made from the crystalline mineral skutterudite, which can contain cobalt, arsenide, nickel or iron. To achieve the desired effect, skutterudite needs to be mixed with lanthanum, cesium, neodymium, or other rare-earth elements, but researchers are exploring less expensive materials such as mischmetal, a naturally occurring alloy that is commonly used as a flint in lighters.
Image: Purdue doctoral student works with a laser to study thermoelectric generators, by Mark Simons courtesy of Purdue University.
Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.