Researchers at Ohio State University have invented a new material that will make cars even more efficient by converting heat wasted through engine exhaust into electricity. Scientists call such materials thermoelectric materials, and they rate the materials' efficiency based on how much heat they can convert into electricity at a given temperature. Previously, the most efficient material used commercially in thermoelectric power generators was an alloy called sodium-doped lead telluride, which had a rating of 0.71. The new material, thallium-doped lead telluride, has a rating of 1.5 -- more than twice that of the previous leader.
What's even more important, however, is that the new material is most effective between 450 and 950 degrees Fahrenheit -- a typical temperature range for power systems such as automobile engines. Some experts argue that only about 25 percent of the energy produced by a typical gasoline engine is used to move a car or power its accessories, and nearly 60 percent is lost through waste heat â€“ much of which escapes in engine exhaust. A thermoelectric (TE) device could capture some of that waste heat and put it to use. It would also make a practical addition to an automobile, because it has no moving parts to wear out or break down.
According to project leader Joseph Heremans, Ohio Eminent Scholar in Nanotechnology at OSU, "The material does all the work. It produces electrical power just like conventional heat engines -- steam engines, gas or diesel engines -- that are coupled to electrical generators, but it uses electrons as the working fluids instead of water or gases, and makes electricity directly."