LED light powered by gravity. Lift a 20lb weight for 30 minutes of light [#power]
December 12th, 2012 by rbanks
GravityLight tackles weighty issue of lighting in the developing world
"The GravityLight is an LED lamp that works by harnessing the gravitational force exerted on a weight hanging from the lamp. One lift of a 20-pound (9 kg) weight, (which is formed by filling the fabric bag the light is delivered in with rocks or sand), generates enough power to provide 30 minutes of light with no need for rechargeable batteries or fuel, which means no running costs." 
via Gizmag
