Exhaust heat to help with gas mileage? GM and BMW think so
By Justin Montgomery
In a quest to find a useful outlet for exhaust heat that otherwise goes wasted, BMW and GM are testing methods and devices that could convert excess heat from a car’s motor into electricity, and in turn reduce gas mileage to boot. In a world where gas mileage is almost the most important feature on a vehicle, and resources are limited, any waste from a vehicle that can be re-used for something useful is a huge step forward.
GM has already gotten as far as to built a prototype which amounts to a small metal-plated device that’s designed to fit around an exhaust pipe. The company predicts that it could improve fuel efficiency in a Chevrolet Suburban by about five percent, or 1 mile per gallon, according to CNet. While this isn’t much, the improvements would be greater in smaller, more fuel-efficient vehicles.
The process, while a bit complicated, involves the age-old technology of thermoelectricity. In its simplest form, it’s the process of using temperature differences to produce electricity. A good example of this technology in use is in “cooled seats” that are appearing in luxury vehicles these days. Thermoelectric researchers at Ohio State University are working with auto companies to develop a method that could improve the efficiency of existing materials by producing an electric current from differences in temperature.
If everything works right, the idea is to use the heat from an engine to produce that electric current, and then channel the energy into a useful form that can be applied to a number of things. It’s estimated that 30-40% of an engine’s heat is already used in one way or another, but auto companies are trying to put the other 60-70% to use.
I don’t completely understand how and why this method could increase fuel efficiency, unless they can greatly improve the science and create a large enough amount of power from exhaust fumes to make a noticeable difference. A one mile per-gallon improvement for a Chevy Suburban doesn’t even sound worth it, but I guess I can see the overall potential. What happens if most cars go hybrid? No exhaust means no added electricity.
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Stumble It!
August 12th, 2008
“I don’t completely understand how and why this method could increase fuel efficiency … ”
Hi Justin: Producing electricity from exhaust heat could replace the vehicle’s alternator, which is driven by a belt run by the motor. Not driving an alternator belt would give the motor more power per unit of fuel consumed, which would allow it to do the same amount of work with less fuel.
August 12th, 2008
“In a quest to find a useful outlet for exhaust heat that otherwise goes wasted, BMW and GM are testing methods and devices that could convert excess heat from a car’s motor into electricity, and in turn reduce gas mileage to boot. ”
REDUCE gas mileage? They’re going to be in the poo with us greenies.
Moral: Always proof read your typing.
August 28th, 2008
Auto Fanatic said, If I can use some of that heat energy and convert it to electricity, you can improve the overall efficiency, It is good to hear this great idea. We hope for more better ideas and more technologies to come.