Soldiers, students, hikers and business people can soon leave extra batteries for things like night-vision goggles, iPods, Global Positioning Systems and cell phones at home, thanks to an innovative new backpack design.
Announced by the American Association for the Advancement of Science (AAAS) earlier this month in the journal Science, the “Suspended-Load” backpack holds promise as the pack of the future.
Designed by Larry Rome of the University of Pennsylvania, the pack works off a fairly simple but often overlooked principle: the rising and falling of the human hips. “Human hips rise and fall about five centimeters with each step,” according to the AAAS. The pack harnesses this motion and turns it into energy.
Springs attach the actual cargo compartment to a frame that a person wears on his or her back.
As the wearer walks along, the pack bounces up and down five or six centimeters. As it bounces, a rod with teeth on it turns the small generator, churning out electricity that could be used to charge any device requiring batteries.
Energy, however, is never free.
The person wearing the pack foots the bill, paying in calories, for each bounce of the pack.
“The energy you exert could be offset by carrying an extra snack, which is nothing compared to the weight of extra batteries,” Rome said. “Pound for pound, food contains about 100-fold more energy than batteries.”
“I wouldn’t want to wear it,” said Jeff Johnson, of the Outdoor Recreation Center.
He explained that the external frame design puts the weight further from the body and makes the pack awkward to wear.
If the spring-generator design were applied instead to something like a water bottle attached to a pack, Johnson said that would be something he would use.
Although research continues, Larry Rome and his colleagues disagree. They believe that the backpack may be less stressful on the back than normal because of the vertical movement.
Backpack makers such as JanSport, Columbia or North Face haven’t said that they had plans to make a backpack with the design.
REI, however, did say they were watching to see the level of interest developed in this type of product.
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