I don't know about you, but I remember swirling my key ring when I had nothing better to do in my younger days. If this concept by Song Teaho and Hyejin Lee had gone into production back then, I would have done my part to save the environment while getting a quick power fix for my phone's battery.
The designers have even come up with a formula in the sketch after the jump (though to be completely honest, I think it's just a bunch of numbers and scientific terms) that proposes that swirling the battery 130 rounds will generate enough power for a 2-minute call or 25 minutes of standby time. Which should be long enough to make a distress call.
(Source: Crave Asia via Engadget)