It's not the first concept we've heard of that uses human motion to charge our batteries, but it could be far more efficient than anything up to now.
Researchers at the University of Wisconsin in Madison say that one day soon, any portable device--including the meatiest smartphones--could be charged by simply taking a stroll.
"Humans, generally speaking, are very powerful energy-producing machines," Tom Krupenkin, a UW-Madison associate professor of mechanical engineering, said yesterday in a statement. "While sprinting, a person can produce as much as a kilowatt of power."
Just a fraction of that energy could easily power not only phones, but also laptops, flashlights and a host of other portable devices. Krupenkin and senior scientist J. Ashley Taylor propose harvesting that power via a novel technology dubbed "reverse electrowetting," which relies on a phenomenon discovered by the researchers and detailed in the journal Nature Communications.
Reverse electrowetting, in layman's terms, is a process by which the energy of moving liquid is converted into electricity. When embedded in footwear, the researchers believe it could convert the energy generated through walking--which is normally lost as heat--into as much as 20 watts of electricity. That's enough to light up a compact fluorescent bulb and hundreds of times more power than motion-powered piezo-electric systems can harvest.
The techology isn't available for purchase yet, but Krupenkin and Taylor are looking to change that. They've created a company, InStep NanoPower, in hopes of taking it commercial. They envision a number of possible applications beyond just "walk and charge," such as large-scale use by military forces, in developing countries, or other places where access to electricity is not ubiquitous. Additionally, they see potential for an always-on Wi-Fi hot spot embedded in footwear that acts as a wireless middleman to connect devices to a network. A battery embedded in the footwear and charged by the technology would keep the hot spot active while at rest. The researchers say this approach would also dramatically reduce power consumption by wireless devices.
"You cut the power requirements of your cell phone dramatically by doing this," said Krupenkin. "Your cell phone battery will last 10 times longer."
Clearly the technology has the potential to be a big winner for consumers and the environment, but perhaps the biggest winner of all is Michael Flatley, whose "Riverdance" show can now be brought back to help power cities around the world.