An ingenious invention:
Red Ferret captions:
The GravityLight (featured in the video above) uses a clever belt and pulley system to generate light through the force of gravity. The idea is for the user to pull a bag up to generate enough energy for short periods of light. Because it uses ultra low power LED bulbs, this could mean up to 30 minutes of light for a quick 3 second hoist. It’s much cheaper than solar (which needs batteries to store the sun’s power) and easier to maintain than other more complex devices.
(Hat tip: Perry)
The Dish 