GM, Research Partners Win Grant To Develop Prototype Exhaust-Heat Generator

Batteries, solar roofs and engine-driven generators aren't the only places tomorrow's cars and tucks may be getting some of the electrical energy they need to keep running.

GM, which has been working on energy recovery from exhaust heat for decades, has just received a small federal grant to develop a prototype exhaust-hear generator using a class of material called Shape Memory Alloy.

SMA, as it is called, is a metal that shrinks when heated and returns to its original shape when cooled. That activity is motion and motion is energy.

A loop of wire made from SMA could use its shrink-and-stretch cycles to drive a generator, said Jan Aase, director of GM's Vehicle Development Research Laboratory.

The idea of an SMA "heat engine" has been around for 30 years, said   Aase, "but the few devices that have been built were too large and too inefficient to make it worthwhile."

That apparently includes a bulky exhaust-heat generator prototype GM showed off for a brief time last year.

It used metal plates that were welded  in a multi-sided collar around an exhaust pipe and created electricity when electrons on the exhaust side of the metal plates were heated and began vibrating, flowing through to the cooler outside of the plates where they were collected by electrodes.

The $2.7 million grant SMA from the Energy Department will enable GM and several partners to develop a working prototype of an exhaust-generator that can provide power for air conditioners, heaters, power windows, stereo systems and other electrical devices on board a vehicle that now drain valuable juice from the battery.

A Chevrolet Suburban reportedly produces up to 15 kilowatts of exhaust heat energy during city driving - enough to power three or four air conditioners simultaneously without any drain on engine power or impact on fuel economy.

"No one else anywhere in the world is doing this work as far as we know," Aase said. "In a hybrid system, the electrical energy could be used to charge the battery. In a conventional engine, this could perhaps even replace the alternator without any load on the engine."

The award from the Department of Energy's Advanced Research Program Agency - Energy,  an ARPA-E grant, will fund GM's work over the next two years with two Southern California partners, HRL Laboratories and Dynalloy Inc. -a manufacturer of shape memory alloys used as device actuators - and the Smart Materials Collaborative Research Lab at the University of Michigan.

"The days are gone when we would do this kind of groundbreaking work on our own," said AlanTaub, vice president of global R&D at General Motors, referring to the dramatic economic collapse of the past year and to GM's own bankruptcy and on-going recovery effort.

John O'Dell, Senior Editor

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John O'Dell November 4, 2009, 4:01 AM

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General Motors

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ARPA-E Grants, Exhaust Heat Energy, Exhaust Heat Generator, General Motors, SMA

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