Researchers at Boston College (BC) and the Massachusetts Institute of Technology (MIT) have used nanotechnology to achieve a major increase in thermoelectric efficiency, a milestone that paves the way for a new generation of products—from semiconductors and air conditioners to car exhaust systems and solar power technology—that run cleaner.
The team’s low-cost approach involves building tiny alloy nanostructures that can serve as microcoolers and power generators. The researchers said that, in addition to being inexpensive, their method likely will result in practical, near-term enhancements to make products consume less energy or capture energy that otherwise would be wasted.
The findings represent a key milestone in the quest to harness the thermoelectric effect, which has both enticed and frustrated scientists since its discovery in the early 19th century. The effect refers to certain materials that can convert heat into electricity and vice versa. But there has been a hitch in trying to exploit the effect: Most materials that conduct electricity also conduct heat, so their temperature equalizes quickly. In order to improve efficiency, scientists have sought materials that will conduct electricity but not similarly conduct heat.
Using nanotechnology, BC and MIT researchers produced a big increase in the thermoelectric efficiency of a semiconductor alloy that has been commonly used in commercial devices since the 1950s. The achievement marks the first such gain in 50 years, using the cost-effective material that functions at room temperatures and up to 250°F. The success using the relatively inexpensive and environmentally friendly alloy means the discovery can quickly be applied to a range of uses, leading to higher cooling and power generation efficiency.
“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 Zhifeng Ren, a Boston College physicist and one of the leaders of the project. “This method is low cost and can be scaled for mass production. This represents an exciting opportunity to improve the performance of thermoelectric materials in a cost-effective manner.”
Thermoelectric materials have been used by NASA to generate power for far-away spacecraft. These materials have been used by specialty automobile seat makers to keep drivers cool during the summer, and the auto industry has been experimenting with ways to use thermoelectric materials to convert waste heat from car exhaust systems into electric current to help power vehicles. In the coming years, electrical contractors could see similar principles applied to the electrical industry.