Using Exhaust to Increase Fuel Efficiency

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One of the more embarrassing facts about modern automobile engines is how inefficient they are at harnessing the energy from fuel. It's estimated that two thirds of the energy contained in gasoline is wasted as heat. One obvious solution is to reuse this heat to generate more energy.

The traditional way of converting heat to electricity involves devices called thermoelectrics. These are semiconductor materials, such as bismuth telluride, that are highly responsive to differences in temperature, which have electrical potential. The problem with these devices is that they can be expensive and inefficient at high temperatures.

However BSST, a Californian company, has created ‘Thermoelectric Generators’ using different semiconductor materials treated with hafnium and zirconium, which they claim are much cheaper and about 40 percent more efficient than their telluride counterparts.

In fact, automobile companies including BMW, Ford and Chevrolet are set to test this technology by the end of this summer. According to Technology Review, the company has performed computer simulations on a Chevrolet Suburban test vehicle and calculated a 3 percent increase in fuel economy.

A major factor in the performance of these thermoelectric generators is directly tied to the effectiveness of the thermoelectric materials used. The company is currently trying to hone in on the most efficient fabrication process so that they can pump out these generators with a high level of confidence.   

Naturally the efforts to increase fuel efficiency are very expansive and include more than just exhaust heat recycling, but it seems that the performance boost afforded by this new technology is making a big enough splash to garner the attention of some of the biggest players in the automobile industry.

Credit: General Motors