March 20, 2008 11:00 AM PDT

Nanotech helps turn 'waste' heat into power

Posted by Martin LaMonica

Update: The headline on this story was corrected to indicate that the research stems from nanotechnology.

Boston College and the Massachusetts Institute of Technology said Thursday they have developed a more efficient way to generate electricity from heat, a technology that could let product designers harness "waste" heat.

Researchers said the implications of efficient thermoelectric materials could be wide: car electronics could be partly powered by the heat captured from exhaust pipes, for example, and solar electric panels could become more productive.

The thermoelectric effect, known since the early 19th century, is when certain materials convert heat into electricity and vice versa. The problem has been that those materials often lose heat quickly as well.

Boston College and MIT researchers have been experimenting with using nanotechnology to increase the efficiency of thermoelectricity.

They broke down bismuth antimony telluride, a commonly used semiconductor alloy, and reconstituted it in a way that slowed the passage of phonons, caused by vibration, through it.

The result is far more efficient process, the researchers said.

"By using nanotechnology, we have found a way to improve an old material by breaking it up and then rebuilding it in a composite of nanostructures in bulk form," said Boston College physicist Zhifeng Ren, one of the leaders of the project, said in a statement.

The advantage of using bismuth antimony telluride as a material is that it's relatively inexpensive, environmentally friendly, and can be used in a wide range of products, including embedded chips in electronics, according to the researchers.