Backpack generates power as you walk
17 September 2005
From New Scientist Print Edition. Subscribe and get 4 free issues.
There are few things more annoying than discovering that the battery on you
mobile gadget has run out of juice where there's no way of recharging it -
in the middle of a long trek, for example, or halfway up a mountain.
Now a novel backpack has been developed that generates electricity as you
walk. The generator, developed by Larry Rome and his colleagues at the
biology department of the University of Pennsylvania in Philadelphia, is
designed to make life easier for troops, field scientists, explorers and
disaster relief workers, by making it unnecessary to carry heavy batteries
into the field.
The device makes use of the fact that a walking person moves like an
upside-down pendulum. "One foot is put down and then the body vaults over
it, causing the hip to move up and down by 4 to 7 centimetres," the
researchers write in the 9 September edition of the journal Science (vol
309, p 1726). This motion is exploited by mounting the bag on a
spring-loaded plate that is free to slide up and down rail-like rods on
either side. As it moves, a toothed rod fixed to the load plate meshes with
a gearwheel on a dynamo, generating electricity.
The backpack can generate up to 7 watts, which is more than enough to power
a cellphone - even a modern one with power-draining colour screens or Wi-Fi
and GPS connections. In tests, the backpack's power output increased with
walking speed and with the weight of the load in the pack. Rome has now set
up a company called Lightning Packs to develop and commercialise the idea.
From issue 2517 of New Scientist magazine, 17 September 2005, page 19
--
Dave Fawthrop <dave hyphenologist co uk>
"Intelligent Design?" my knees say *not*.
"Intelligent Design?" my back says *not*.