Scientists turn car exhaust into electricity, twice as efficiently

By Michael Hatamoto, BetaNews

July 25, 2008, 5:27 PM

Scientists from Ohio State University have created a new material called thallium-doped lead telluride, which has been designed to convert car engine exhaust heat into electricity.

The research team led by Joseph Heremans said the material could also be used to help power generators and heat pumps. The new material is reportedly able to convert the wasted heat into energy without causing pollution, and do so more efficiently than was previously possible.

"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," Heremans said in a statement on the OSU web site.

Its expected operating environment, between 450° and 950° Fahrenheit, is the normal range of car engines. Just 25 percent of the energy from a gasoline car engine is used to actually move the car, so the discrepancy between necessary energy and wasted energy is substantial.

Published studies previously indicated as much as 60 percent of energy loss in a gasoline engine is because of waste heat that is not disposed of properly.

Although thermoelectric materials used to generate power aren't revolutionary, the OSU research team has made several small adjustments to make its material more efficient. They were able to double the efficiency rating from 0.71 up to 1.5.

An alloy called sodium-doped lead telluride previously was the most efficient material, which had the 0.71 rating.

The discovery by Heremans at OSU is the latest in a string of events that started after years of research by other universities. Michigan State University researchers who published a quantum mechanics report on thallium and tellurium in 2006 helped OSU better understand what they were dealing with beforehand.

Furthermore, OSU was helped in testing the material from Osaka University and the California Institute of Technology.

Moving forward with their research, Heremans and his team hope to further increase the efficiency rating of the new material.