Engineers at Purdue University are using thermoelectric generators (TEG) to turn heat from car-engine exhaust into electricity. The electricity could then be used to charge the battery or power a car’s electronics. Either way, the additional electricity should reduce the workload on the gas engine and increase mileage.
The current prototype uses gases as hot as 1,300°F, which should boost mileage by 5%. The engineers are developing TEG that can use gases at significantly higher temperatures and thereby increase mileage by 10%.
TEG use a few square inches of thermoelectric material that use temperature differences to generate electricity. A goal is to develop a material that is a poor heat conductor. That’s because the unit needs to maintain the temperature difference; it doesn’t work efficiently if the heat moves rapidly from the hot side to the cool side. The current material being used is called skutterudite, an alloy of cobalt that can include arsenide, nickel, and iron. Material engineers add rare-earth elements to reduce the thermal conductivity of skutterudite.