Even hybrid vehicle engines create emissions, many of which are harmful to the environment. However researchers at Purdue University have created a system that harvests heat from a car’s exhaust in order to generate electricity and reduce the vehicle’s fuel consumption. The innovative engine design has been funded by a $1.4 million, three-year grant from the National Science Foundation and the U.S. Department of Energy. The ‘thermoelectric generator’ was created in collaboration with General Motors who hopes to put the prototype into commercial production.
According to Xianfan Xu, a Purdue professor of mechanical engineering and electrical and computer engineering, that thermoelectric generators (TEGs) can generate an electric current capable of charging batteries and powering a car’s electrical systems. This in turn would reduce the engine’s workload and improve the car’s fuel economy.
The university’s prototype is designed to be installed as part of a vehicle’s exhaust system behind the catalytic converter, and it will harvest energy from the 700 degrees Celsius exhaust gases. According to Xu, current thermoelectric technology cannot withstand the temperatures inside catalytic converters, where gases are about 1,000 degrees Celsius. As a result, the team is working on TEGs capable of withstanding such high temperatures, enabling greater fuel savings. So far the prototype has reduced fuel consumption by five percent, but the team believe that if they can get it to withstand higher temperatures, the reduction would increase to 10 percent.
Researchers at GM are currently using a thermoelectric material called skutterudite — a mineral made of cobalt, arsenide, nickel or iron — to make the prototype. “The biggest challenge is system-level design – how to optimize everything to get as much heat as possible from the exhaust gas,” Xu said. “The engine exhaust has to lose as much heat as possible to the material.” This innovation could truly transform the auto industry, so it is good to see General Motors involved in its development.