Lift a Rock to Power a Light
Another ingenius invention – a light that is powered by gravity. GravityLight, developed by Deciwatt, is powered by the weight of a bag of rocks or dirt as it descends. You simply attach a fabric bag filled with rocks, sand or earth, then attach it to the light’s cord to power the light for up to half an hour. The light can also be adjusted for a task light or down for a gentle glow. They are working on increasing it’s efficiency and cost to make this light available to people in areas without reliable electricity and those who use kerosene for light.
Check out more on their website: deciwatt.org