Researchers from the University of Wisconsin-Madison have improved their ability to generate considerably more electricity from human footfalls.
Previous attempts to generate electricity from walking using shoes have only been able to generate less than a watt of power, but a new technique could lead to an in-shoe generator that produces up to 10 watts, says Tom Krupenkin, a mechanical engineering professor who led the work.
“A lot of energy is simply wasted as heat while we walk” says Tom Krupenkin. “If one can convert this into electrical energy, numbers come out to be up to 10 watts per foot.” Cell phones and smart phones need about one to two watts, while small laptops need 10 to 12 watts. Electricity-generating shoes could benefit soldiers that are deployed to very remote areas that have no electricity/lack infrastructure overall. They currently carry heavy batteries to power their radios, GPS units, and night-vision goggles. They have to carry as many batteries as they can to ensure that their equipment can always function.
The process of walking exerts a significant force on the heel and toe, and cushioned soles can compress as much as a centimeter with every step. Energy harvesters utilize this force to generate electricity.
“It’s a unique approach to energy harvesting,” says Andrew Haughian, one of the partners of a Vancouver, Canada-based venture capital firm Pangaea Ventures, which is analyzing the technology for potential investment. “The biggest opportunity I see would be in [developing countries], where the power grid is not reliable.”
It might be years before you can buy a power-generating shoe, though. So far, the researchers have only made an array of 150 droplets that gives a few milliwatts of power. However, they claim that a device with 1,000 droplets in a 4 metre long, 1 mm wide channel, which would cover an area of 40 cm2 and fit in a shoe, could generate a few watts of electricity.