This Wired article just caught my attention.
British engineers are converting street vibrations into electricity and predict a working prototype by Christmas capable of powering facility lights in the busiest areas of a city.
"We can harvest between 5 to 7 watts of energy per footstep that is currently being wasted into the ground," says Claire Price, director of The Facility Architects, the British firm heading up the Pacesetters Project. "And a passing train can generate very useful energy to run signaling or to power lights."
Gilbert is working with hydraulic-powered heel-strike generators, which he believes could be installed in the floors of busy public places like subway stations. Those stations typically capture the footfall of 20,000 commuters an hour during peak usage -- multiplied by 5 to 7 watts a person, that's more than enough to power a building's lights for the day.
The prototypes are scheduled for assembly by December 2006.
I think it's a cool idea. I hope they can make it work.