A group of US researchers is about to start work on a system that uses heat from a vehicle’s exhaust to generate electricity and reduce fuel consumption.
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The engineering team from Indiana’s Purdue University was granted $US1.4 million ($1.42 million) over three years by the US Department of Energy and the National Science Foundation to develop a prototype of the system, which will use thermoelectric generator (TEG) technology.

Purdue professor of mechanical engineering and electrical and computer engineering, Xianfan Xu, is leading the research and development, which will be conducted in collaboration with General Motors.

The concept is an advanced one, but one with great potential for increasing the efficiency of internal combustion engines.

The TEGs will be inserted into the exhaust system behind the catalytic converter, where temperatures reach up to 700 degrees Celsius. They generate electricity when there is a temperature difference between one face and the other. Therefore, the goal is to develop materials that are poor heat conductors and will not allow the rapid transfer of heat.

Currently, TEG technology is not capable of withstanding such excessive temperatures. The researchers are looking to use a combination of rare-earth elements – including erbium, neodymium, cesium and lanthanum – and skutterudite, as well as developing less-expensive alloys known as “mischmetals”.

Mr Xu said the goal for the first prototype was to improve fuel efficiency by five percent, and said future systems operating at higher temperatures could potentially lead to efficiency gains of up to 10 percent. He said optimisation of heat capturing was the key.

The potential of the system is clearly far wider reaching than just cars, and if successful, could also contribute to improving the efficiency of other sources that create waste heat, such as homes and power plants.

The project will begin on January 1, 2011.