Researchers from Simon Fraser University in British Columbia have developed a device worn much like a knee brace that generates electricity from the natural motion of walking.

The device harvests energy from the end of a walker’s step, when the muscles are working to slow the movement of the leg, in much the same way that hybrid-electric cars recycle power from braking.

Wearing a device on each leg, an individual can generate up to five watts of electricity with little additional physical effort. Walking more quickly generates as much as 13 watts of electricity: at that rate, one minute of walking provides enough electricity to sustain 30 minutes of talk time on a mobile phone.

There is about as much useful energy in a 35-gram granola bar as in a 3.5 kg lithium-ion battery." sfu.ca

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