Exhaust heat could power car electronics

German researchers working on a thermoelectric generators that use the heat from a car̵7;s exhaust to power in-vehicle electronics say they are close to building a prototype device.

The scientists at the Fraunhofer Institute for Physical Measurement Techniques have nearly completed the experimental phase of developing a system which they believe could make a significant contribution to improving fuel efficiency.

A number of groups are looking at ways of harnessing unused waste heat. In a car, for example, two-thirds of energy from combustion is emitted unused in the form of heat; about 30 per cent through the engine block and 30 to 35 per cent as exhaust fumes.

Thermoelectric generators could convert this into electrical energy by making use of the temperature gradient of around 700 degrees Celsius that exists between the exhaust pipe and the engine̵7;s coolant fluid. Charge carriers driven by the flow of heat between the two regions pass through semiconductors to produce an electric current.

The technique could cover a significant proportion of a car̵7;s power requirements, and eventually make alternators obsolete, claimed Dr Harald Böttner, head of the Institute̵7;s Thermoelectric Systems Department.

̶0;This would make it possible to cut gas consumption by between 5 and 7 per cent,̶1; he said.

Image: Thermoelectric generators could cut fuel consumption by up to 7 per cent

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