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 MP3
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-crew, ring
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 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! |
