Power From Your Tailpipe? It's Possible

Aug. 11, 2008 -- The stinky, steaming air that escapes from a car's tailpipe could help us use less gas.

Researchers are competing to meet a challenge from the U.S. Department of Energy: Improve fuel economy 10 percent by converting wasted exhaust heat into energy that can help power the vehicle.

General Motors Corp. is close to reaching the goal, as is a BMW AG supplier working with Ohio State University. Their research into thermoelectrics -- the science of using temperature differences to create electricity -- couldn't come at a better time as high gas prices accelerate efforts to make vehicles as efficient as possible.

GM researcher Jihui Yang said a metal-plated device that surrounds an exhaust pipe could increase fuel economy in a Chevrolet Suburban by about 5 percent, a 1-mile-per-gallon improvement that would be even greater in a smaller vehicle.

Reaching the goal of a 10 percent improvement would save more than 100 million gallons of fuel per year in GM vehicles in the U.S. alone.

"The take-home message here is: It's a big deal," Yang said.

The DOE, which is partially funding the auto industry research, helped develop a thermoelectric generator for a heavy duty diesel truck and tested it for the equivalent of 550,000 miles about 12 years ago.

John Fairbanks, the department's thermoelectrics technology development manager, said the success of that generator justified the competitive search in 2004 for a device that could augment or replace a vehicle's alternator. Three teams were selected to participate in the program, with GM and thermoelectrics manufacturer BSST separately working on cars and a team from Michigan State University focusing on heavy-duty trucks.

Fairbanks said thermoelectric generators should be on the verge of production in about three years.

"It's probably the biggest impact in the shortest time that I can think of," he said.