Energy Harvester Generates Electricity from Walking

FRIDAY, Feb. 8 (HealthDay News) -- A novel biomechanical energy harvester that straps to the leg can be used to generate electricity during human walking with little extra effort, according to a report published in the Feb. 8 issue of Science.

J.M. Donelan, of Simon Fraser University in Burnaby, British Columbia, Canada, and colleagues developed a knee-mounted energy harvester that utilizes the generative braking concept, capturing the energy that is normally dissipated during the deceleration phase of a leg stride. The performance of the device was tested on six male subjects who walked on a treadmill at a speed of 1.5 m/second.

By walking with one device on each leg, subjects generated an average of 5 watts of electricity, which is 10 times the amount that shoe-mounted energy harvesters can generate and enough electricity to power 10 cell phones simultaneously. Because the device takes advantage of the leg's deceleration phase, little extra work is added to the walker.

"Several potential applications are especially suited for generative braking. These include lighting and communications needs for the quarter of the world's population who currently live without electricity supply," write the authors. "In implantable devices, such as neurostimulators and drug pumps, battery power limits device sophistication, and battery replacement requires surgery. A future energy harvester might be implanted alongside such a device, perhaps in parallel with a muscle, and use generative braking to provide substantial power indefinitely."

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