Science Daily reports University of Pennsylvania biologists have created a backpack that generates 7.4 watts of electricity.
According to Larry Rome, a professor in Penn’s Department of Biology:
The Suspended-load Backpack is based on a rigid frame pack, much like the type familiar to hikers everywhere; however, rather than being rigidly attached to the frame, the sack carrying the load is suspended from the frame by vertically oriented springs. It is the vertical movement of the backpack contents that provides the mechanical energy to drive a small generator mounted on the frame.
“As humans walk, they vault over their extended leg, causing the hip to rise 5-7 centimeters on each step. Since the backpack is connected to the hip, it to must be lifted 5-7 centimeters,” Rome said. “It is this vertical movement of the backpack that ultimately powers electricity generation.”
The amount of power generated depends on how much weight is in the pack and how fast the wearer walks. The Penn researchers tested packs with loads of 40 to 80 pounds and found that the wearer could constantly generate as much as 7.4 Watts while moving at a steady clip. Typically, cell phones or even night vision goggles require less than one Watt to power.