I was really disappointed by the kneegen article. I always wanted to have a self-powered exoskeleton, and the efficiency is just nowhere close.
Some interesting other attempts to harness energy expended through daily activity have popped up:
Triboluminescence via nanowires
aka, the Power Bra
At one point I wanted to design a liquid-based knee-gen-like system, with a “pump” in the shoe that would force water past tiny paddlewheels (such as from fishtank aerators). This would harvest the footstep energy, which I used to think would be more efficient than knee-bends.
I’m still surprised that efficiency is so low for HVAC systems – I always thought you should be able to hook up the refrigerator’s coolant system to the temperature-difference system that drives the HVAC. In theory it would even be self-sustianing. But this class has taught me that efficient transfer is anything but simple.
I also spent an amusing afternoon looking up “Over Unity” patent attempts. Yes, of course, you’re the only one ever to think of a perpetual motion machine! And all you needed was magnets! MAGNETS EVERYWHERE!