A prototype of the thermoelectric system will be developed next year. Once complete, its characteristics will be assessed by installing it in an exhaust system behind the catalytic converter, where it will harvest heat from exhaust gases at 700oC.
The first prototype aims to reduce fuel consumption of a vehicle by five per cent, while future systems capable of working at higher temperatures could make a 10 per cent reduction possible, according to Purdue engineering professor Xianfan Xu.
Thermoelectric materials generate electricity when there is a temperature difference between one side of them and the other. ’The material is hot on the side facing the exhaust gases and cool on the other side, and this difference must be maintained to continually generate a current,’ said Xu, who has been collaborating with General Motors in thermoelectric research for about a decade.
Researchers at GM are using a thermoelectric material called skutterudite, a mineral made of cobalt, arsenide, nickel or iron that is mixed with rare-earth elements, such as lanthanum, caesium, neodymium and erbium to reduce the thermal conductivity of the skutterudite.