Power Felt can convert heat into an electrical current

Developed by researchers at the Center for Nanotechnology and Molecular Materials at Wake Forest University, Power Felt is comprised of carbon nanotubes locked in flexible plastic fibres and made to feel like fabric. The technology uses temperature differences — room temperature versus body temperature, for instance — to create a charge.

The team’s research appears in the current issue of Nano Letters.

‘We waste a lot of energy in the form of heat. For example, recapturing a car’s energy waste could help improve fuel mileage and power the radio, air conditioning or navigation system,’ said researcher and Wake Forest graduate student Corey Hewitt. ‘Generally, thermoelectrics are an underdeveloped technology for harvesting energy, yet there is so much opportunity.’

Potential uses for Power Felt include lining seats in vehicles to boost battery power and service electrical needs, insulating pipes or collecting heat under roof tiles to lower gas or electric bills, lining clothing or sports equipment to monitor performance, or wrapping intravenous 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 pre-paid cell phone,’ said David Carroll, director of the Center for Nanotechnology and Molecular Materials. ‘Power Felt could provide relief during power outages or accidents.’

Cost has prevented thermoelectrics from being used more widely in consumer products. Standard thermoelectric devices use bismuth telluride to turn heat into power in products, including mobile refrigerators and CPU coolers, but researchers say it can cost $1,000 per kilogram. In a similar manner to silicon, they liken Power Felt’s affordability to demand in volume and think it could eventually cost $1 to add to a mobile phone cover.

Currently, 72 stacked layers in the fabric yield about 140 nanowatts of power. The team is evaluating several ways to add more nanotube layers and make them even thinner to boost the power output.

‘I imagine being able to make a jacket with a completely thermoelectric inside liner that gathers warmth from body heat, while the exterior remains cold from the outside temperature,’ said Hewitt. ‘If the Power Felt is efficient enough, you could potentially power an iPod, which would be great for distance runners. It’s definitely within reach.’

Wake Forest is in talks with investors to produce Power Felt commercially.