Researchers Create Composite That Converts Engine Heat to Electricity in Cars

Being able to harvest engine heat from cars and redirect it into charging batteries or powering supplementary systems is likely the best way to improve efficiency in next-generation hybrid cars, according to a team of scientists from the University of Manchester.

As reported Aug. 4, about 70% of the energy that cars currently generate through fuel consumption is lost to heat. A thermoelectric material — one that can generate an electrical current from heat — would therefore allow cars to become much more efficient. Already, hybrid vehicles are much more efficient than gas-powered cars (which allows owners to recoup their investments, given that hybrid vehicles cost 15-20% more, on average).

Previously, most of the thermoelectric materials available were highly toxic and only worked at temperatures higher than those produced by cars. But the team’s new research has found that adding graphene to a composite material would allow cars to convert heat to usable electricity and reduce global carbon emissions from vehicles.

“Our findings show that … introducing a small amount of graphene to the base material can reduce the thermal operating window to room temperature, which offers a huge range of potential for applications,” lead researcher Ian Kinloch told

The composite still doesn’t allow for total heat capture, he said, but it’s a start. “The new material will convert 3-5% of the heat into electricity. That is not much but, given that the average vehicle loses roughly 70% of the energy supplied to it by its fuel to waste heat and friction, recovering even a small percentage of this with thermoelectric technology would be worthwhile,” he explained.

The team’s findings have been published in the journal ACS Applied Materials and Interfaces.

Fuel efficiency is becoming increasingly important in hybrid and completely gas-powered cars alike, especially as the government has imposed new efficiency goals on the auto industry. By 2015, any manufacturers selling vehicles on the U.S. market will have to achieve an average fuel economy of 54.5 miles per gallon.

Interestingly enough, however, consumers don’t seem to be willing to pay more for higher-efficiency vehicles, according to recent comments from Forrest McConnell, last year’s president of the National Automobile Dealers Association.

But an executive for electric car maker Tesla says that’s a short-sighted view. Diarmuid O’Connell, vice president of business development, recently commented at an auto event in northern Michigan that automakers need to be focused on attaining even higher efficiency than the government is mandating.

“We’re living in a time of cheap gasoline, but this is probably an ephemeral event,” he cautioned.

Leave a Reply