Backpack generates electicity
The image above shows a 'suspended-load backpack' which was recently developed by Lawrence Rome, a biologist at the University of Pennsylvania. The luggage compartment travels up and down on the frame as the user walks, turning a gear which drives a small generator. The amount of power generated depends on how much weight is in the pack and how fast the user walks. Researchers measured a maximum output of 7.4 watts. Seven watts is sufficient to power a handful of electronic gadgets at the same time, including a cell phone, an MP3 player, a handheld computer, night-vision goggles, and a water purifier.
via treehugger