Ted Harman at MIT's Lincoln Laboratory--building in part on Chen's earlier, unrelated work--showed that by using nanostructures, you can create materials that outdo nature: Some of Harman's materials, thanks to their unique heat-impeding qualities, are twice as efficient as their conventional cousins.
Chen says innovations like an exhaust-mounted energy-mining device for vehicles needn't wait until you hit Lincoln Lab realms of efficiency. "If you can reach a 10-to-15 percent conversion efficiency," he says, "that would be attractive for many applications." In fact, results he's had at that level are already drawing interest from companies.
Thermoelectric devices are energy converters. When they're producing electricity, this puts them in the same broad category as power plants and solar-generating systems. When outputting heat or its opposite, meanwhile, they're like heat pumps and air conditioners, respectively.
In design terms, thermoelectric devices have key pluses. For one, they're solid state: no liquid fuels, no moving parts. They're also easily scalable up or down.
"Cars are about 20 percent efficient," notes Chen, "and turning some of the energy wasted into electricity could increase that figure by as much as one-third."