Backpacks are convenient. They can hold your books, your lunch, and a change of clothes, leaving your hands free to do other things. Someday, if you don't mind carrying a heavy load, your backpack might also power your MP3 player, keep your cell phone running, and maybe even light your way home.
Scientists from the University of Pennsylvania in Philadelphia and the Marine Biological Laboratory in Woods Hole, Mass., have invented a backpack that makes electricity from energy produced while its wearer walks.
Inventor Larry Rome of the University of Pennsylvania wears his electricity-generating backpack.
|Image courtesy of Larry Rome.|
The backpack's electricity-creating powers depend on springs used to hang a cloth pack from its metal frame. The frame sits against the wearer's back, and the whole pack moves up and down as the person walks. A mechanism with gears collects energy from this motion and transfers it to an electrical generator.
Surprisingly, the researchers found, people walk differently when they wear the springy packs. As a result, wearers use less energy than when lugging regular backpacks. Also, the way the new packs ride on wearers' backs makes them more comfortable than standard packs, the inventors say.
In the new backpack, the pack frame is attached to the body but the cargo-carrying part hangs from springs attached to the frame. As you walk, the cargo compartment jiggles and a special toothed rod (green) moves up and down, turning a gear mounted on a g
The backpack could be especially useful for soldiers, scientists, mountaineers, and emergency workers who typically carry heavy backpacks. These people often rely on global positioning system (GPS) receivers, night-vision goggles, and other battery-powered devices to get around and do their work. Because the pack can make its own electricity, users don't need to give up space in their packs to lots of extra batteries.
For the rest of us, power-generating backpacks could make it possible to walk, play video games, watch TV, and listen to music, all at the same time. Electricity-generating packs aren't on the market yet, but if you do get one eventually, just make sure to look both ways before crossing the street!—E. Sohn
Weiss, Peter. 2005. Getting a charge out of backpacking.  Science News 168(Oct. 1):221. Available at http://www.sciencenews.org/articles/20051001/note11.asp  .
You can learn more about the electricity-generating backpack at www.upenn.edu/pennnews/article.php?id=841  (University of Pennsylvania).