Electric Backpack
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
backpacks might also power your MF3 player, keep your cell phone running, and
maybe even light your way home.
Lawrence C. Rome and his
colleagues 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. In military actions,
search-and-rescue operations, and scientific field studies, people rely
increasingly on cell phones, global positioning system (GPS) receivers,
night-vision goggles, and other battery-powered devices to get around and do
their work. The backpack’s electricity-generating feature could
dramatically reduce the amount of a wearer’s load now devoted to spare
batteries, report Rome and his colleagues in the Sept. 9 Science.
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 gear mechanism converts
vertical movements of the pack to rotary motions of an electrical generator,
producing up to 7.4 watts.
Unexpectedly, tests showed that
wearers of the new backpack alter their gaits in response to the pack’s
oscillations, so that they carry loads more comfortably and with less effort
than they do ordinary backpacks. Because of that surprising advantage, Rome
plans to commercialize both electric and non-electric versions of the
backpack.
The backpack could be especially useful for soldiers,
scientists, mountaineers, and emergency workers who typically carry heavy
backpacks. 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 lime.
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! |
