[lit-ideas] Backpack generates power from walking

  • From: JimKandJulieB@xxxxxxx
  • To: lit-ideas@xxxxxxxxxxxxx
  • Date: Fri, 9 Sep 2005 21:07:50 EDT

_Click  here: CNN.com - Backpack generates power from walking - Sep 9, 2005_ 
(http://www.cnn.com/2005/TECH/09/09/backpack.reut/index.html)  
 
     
Backpack generates power from walking


WASHINGTON (Reuters) -- A backpack that  converts a plodding gait into 
electricity could soon be charging up mobile  phones, navigation devices and 
even 
portable disc players, U.S.-based  researchers said on Thursday. 
Their backpack design converts mechanical energy from up-and-down  movement 
of the backpack's cargo to electricity during normal walking. 
Fueled by a snack, hikers can put the spring in their steps to good  use, the 
researchers write in Friday's issue of the journal Science. 
The backpack is deliberately designed to shake around a bit. The  up-and-down 
movement of the backpack's cargo compartment against the frame  of the pack 
turns a gear connected to a generator. 
The simple magnetic coil generator is similar in principal to those  seen in 
hand-cranked radios, flashlights that work after a rhythmic  shaking and other 
devices. 
Humping along just under 85 pounds (38 kg) of weight in the backpack  can 
produce up to 7 watts of electricity, Lawrence Rome and colleagues at  the 
University of Pennsylvania report. 
This is more than enough electricity to simultaneously power an MP3  music 
player, a personal digital assistant, night vision goggles, a  handheld global 
positioning satellite navigation device, and a mobile  telephone. 
The not-so-graceful human gait is a big help in making the pack work,  they 
reported. 
Human hips rise and fall about 2 inches (5 cm) with each step and a  backpack 
worn by a person who is walking rises and falls as well, they  said. 
"As humans walk, they vault over their extended leg, causing the hip to  rise 
5 to 7 centimeters on each step. Since the backpack is connected to  the hip, 
it too must be lifted 5-7 centimeters," Rome said in a  statement. 
"It is this vertical movement of the backpack that ultimately powers  
electricity generation." 
But nothing is free, so what does this energy cost the hiker? 
Little more than a snack, said Rome. 
"Metabolically speaking, we've found this to be much cheaper than we  
anticipated. The energy you exert could be offset by carrying an extra  snack, 
which 
is nothing compared to weight of extra batteries," Rome  said. 
"Pound for pound, food contains about 100-fold more energy than  batteries." 
 
Copyright 2005 _Reuters_ (http://www.cnn.com/interactive_legal.html#Reuters) 
. All rights  reserved.This material may not be published, broadcast, 
rewritten, or  redistributed.
    

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