The PowerWalk enables users to produce 10-12 watts of power as they walk. Over the course of an hour, walking at a comfortable pace, users wearing a harvester on each leg can generate enough power to charge up to four smart phones.
The system typically can generate enough power from one hour of walking to recharge four smartphones. The product is initially intended for military use; if a soldier can generate extra electricity while walking, it reduces the weight of the batteries that he or she must carry. It also means that new batteries don’t have to be replaced in the field, which can simplify resupply logistics and make it possible to extend the length of missions. The device can even save the wearer some energy; when walking downhill, the device automatically increases its resistance (and power generation) which reduces the load on the wearer’s legs.
How does it work?
The light-weight PowerWalk harvester is designed to generate electricity from the natural action of walking, in much the same way regenerative braking works in hybrid cars. With every stride, the harvester’s on-board microprocessors analyze the wearer’s gait to determine precisely when to generate maximum power with the least amount of effort.
The PowerWalk’s gearbox converts the knee’s rotational speed to a higher speed for efficient power generation and a generator converts the mechanical power produced into electrical power. A state-of-the-art power-conversion circuit then converts the electricity to recharge Li-ion or NiMH batteries.