http://dvice.com/archives/2008/12/revolving_door.php
Check out this article at DVICE. Immediately I’m thinking of other ways we can harness energy from human movement. Think of *ALL* those people at the gym on stairclimbers, friction weight machines, etc. The friction on all those machines could be created by electricity generating systems.
Imagine a model where your gym membership was free because the gym’s could “sell” the electricy you generated while exercising to the grid.