Powered by Felt

It promises to be the most widely and easily distributed power generation technology to date: heat, captured in fabric. Work at Wake Forest University in North Carolina has led to the creation of a thermoelectric fabric called Power Felt that can turn theoretically any form of heat (body heat, waste heat from a car, or heat from any other source to which the material can be attached) into sufficient electrical current to help power devices or the systems the material is in contact with (Figure 7).

7. Power. Felt. A thermoelectric fabric called Power Felt, shown here conducting a charge, was developed in the nanotechnology laboratory of Wake Forest University. Its physical and operational flexibility promises to be useful in a wide array of applications. Courtesy: Wake Forest University

As the abstract of an article about this research in the February issue of Nano Letters explains, “Thermoelectrics are materials capable of the solid-state conversion between thermal and electrical energy. Carbon nanotube/polymer composite thin films are known to exhibit thermoelectric effects.” Although such composite thin films are not very powerful, when layered into modules resembling felt fabric, power output increases.

“Since these fabrics have the potential to be cheaper, lighter, and more easily processed than the commonly used thermoelectric bismuth telluride, the overall performance of the fabric shows promise as a realistic alternative in a number of applications such as portable lightweight electronics.”

Researchers suggest that potential uses for Power Felt include lining automobile seats to boost a car’s battery power and service its electrical needs, insulating pipes or collecting heat under roof tiles to lower buildings’ gas or electric bills, lining clothing or sports equipment to monitor an athlete’s performance, or wrapping IV or wound sites to better track patients’ medical needs.

“Imagine it in an emergency kit, wrapped around a flashlight, powering a weather radio, charging a prepaid cell phone,” says David Carroll, director of the Center for Nanotechnology and Molecular Materials and head of the team leading this research. “Literally, just by sitting on your phone, Power Felt could provide relief during power outages or accidents.”

The university is exploring options to produce Power Felt commercially. Although even widespread application of this clean and energy efficient power generation technology likely would not threaten the existence of utility-scale generating stations, it could contribute to lower demand increases. That may be seen as a loss for power companies in developed countries with ample generation options, but it could be a boon for both generators and consumers in capacity-stretched nations. Then there’s the convenience of knowing that as long as your body is alive (that is, warm), you’ll never worry about a dead cell phone battery.

—Sonal Patel is POWER’s senior writer.