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With this personal energy generator, charge your phone simply by taking a walk. Photo: nPower

The name pretty much says it all: Personal energy generator.

All the new 14-ounce device from needs is your body. Literally. The —we’ll call it Peg for short—takes the energy you create through biking, running, even walking and uses it to charge your portable electronics. It can’t do a laptop and only minimally charges an iPad, but it can get an iPhone back to full power. Not too shabby.

Ok, so you want to know how Peg works, right? It’s all about kinetic energy—the energy derived from motion. (Tremont’s “” page gives a really great, detailed explanation.) Essentially, a magnet inside Peg mounted to a spring bounces up and down when you move, creating an electric charge. The more kinetic energy you generate, the greater the charge. There’s potential for larger-scale use, too, Tremont touts. “Your PEG, attached to you, can power a handheld device, but if it’s built the size of a car and floating on open water, it can pump commercial scale electricity into the grid.”

We love this cheat sheet from Tremont for how much walking’s required to get the power you need (the company is careful to state that “output varies widely by user, activity, and device”):
- 1 minute walking = about 1 minute listening to an iPod Nano
- 11 minutes walking = about 1 minute of talking on a 2G cell phone
- 26 minutes walking = about 1 minute of talking on a 3G cell phone

The baton-shaped Peg isn’t the first to use what the .” ’s recycled-rubber tiles (which we wrote about in our Jan-Feb 2012 issue) use kinetic energy generated from walkers’ footsteps to light up nearby LED lampposts. The London Olympics will employ the green tech this summer. And in 2011, Science reported that two researchers from Wisconsin—who later formed the company —came up with “a novel energy-harvesting device that converts mechanical motion into electrical energy at a high enough power to recharge cell phones, cameras, and myriad other portable electronic devices.” The idea is to create a prototype that fits inside a shoe.

Now, if you forget your phone charger, you’ve got a back-up handy. Just pull out Peg and you’re all set. Here’s hoping you didn’t leave the personal energy generator at home, too.