Generating electricity from vehicle exhaust

Researchers at the Fraunhofer Institute of physical measurement techniques (IPM) is currently developing a thermoelectric generator that converts the heat exhaust of cars into electricity. This module could serve as a power source for electronic systems in vehicles. Hence, the system would allow a reduction of fuel consumption, and hence a fortiori a decrease in CO2 emissions from motor vehicles. Indeed, two thirds of fuel would be lost as heat during operation of the car: about 30% in the grouping engine and 30% to 35% in vehicle exhaust.

The thermoelectric generators convert heat into electrical energy using the temperature gradient over the temperature difference is, the more these generators produce electricity. To reach their goal, researchers at the IPM developing thermoelectric materials, modules and systems adapted to the automobile. "In the exhaust duct, temperatures reach up to 700 ° C and more," says Dr. Harald Böttner, director of thermoelectric systems, where a temperature gradient between the exhaust duct and the circuit coolant of several hundred degrees Celsius. "The processor operates thermoelectric this great gap," he continues. Trained by the flow of heat created between the hot exhaust gases and cooling, porters load through several special semiconductors generating an electric current. In the long term, this generator could make redundant the role of the generator and fuel directly receptors in the electric car, whose number is constantly growing. Thus, "fuel consumption could fall by 5% to 7%", explains Dr. Böttner.

As R&D partner to the industry, the Fraunhofer Institute for Physical Measurement Techniques IPM develops optical sensor and imaging systems as well as systems based on thin film technology. IPM scientists develop novel technical solutions for process measurement, bioanalytical applications, railroad measurement or security technology. Further research focuses are the measurement of geometrical parameters as well as laser imaging. Thermoelectrics has been established as another competence area over the last years.

This technology could be very useful: approximately 50 million motor vehicles in circulation in Germany at a rate of 200 hours per year each. If you could use the heat emitted during this time to feed all the electronic board with a power of a kilowatt, it would save 10 terawattheure each year. The laser systems, which IPM has developed for imaging processes, have been awarded several prizes. Many of Fraunhofer IPM's activities are based on existing know-how; however, we also permanently open up entire new fields of technology.

Researchers are still testing but a first prototype should see the day very soon.