BMW, Ford & GM Testing Ways to Harness Energy From Exhaust Gas

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No matter how fuel-efficient your internal combustion engine is, it will inevitably waste some energy in the form of heat. To make engines more eco-friendly, auto manufacturers are experimenting with harnessing energy from a car’s exhaust gas.

While engine manufacturers have traditionally attempted to get back power from exhaust gas through turbocharging. But the difficulty here is directly harnessing exhaust gas is often indirect, and not really efficient. An experimental technology using thermoelectric semiconductors aims to convert heat into usable energy that can potentially boost efficiency by at least 5%.

Current thermoelectric materials are not yet very efficient and practical, though, and so manufacturers BMW, Ford and GM are working on a solution. GM is currently experimenting on rare earth materials and super-strong alloys for this purpose. So far, GM was able to design a generator that converts exhaust heat into energy, resulting in a 3% fuel economy improvement in a Chevy engine.

The technology is far from cheap, and the cost of materials beats the savings from fuel economy. But this demonstrates that there are other ways of making fuel-fed engines more efficient other than hybrid and other electricity-based solutions that also contribute to the carbon footprint by using energy from the grid.