The promise of thermoelectric materials has, it seems, run hot and cold over the decades. These materials, which can directly convert heat into electricity (and vice versa), could be a boon for everything from power generation to microprocessor cooling. But except in a few niche applications, these solid-state heat pumps have proven too inefficient to be practical. As much as engineers would like to grab waste heat from, say, a cars engine and turn it into electricity, thermoelectric materials just havent been up to the job.

Now, engineers and scientists at several leading labs have used nanotechnology to create novel semiconducting materials that could finally make thermoelectricity a widely used technology. After six to 10 years of pretty intensive basic research, some of these materials are coming to fruition, says Terry Tritt, a professor of physics at Clemson University. Within the last 18 months there have been substantial improvements. Indeed, at least one research group predicts it will soon have prototypes of a practical heat-conversion device that carmakers can begin testing.