How cool is that!
In the majority of developing countries, electricity is scarce or non-existing. Kerosene lamps are being used, but they don't burn cleanly and cause fire. These guys created (2nd version) a lamp that needs only with gravity, isn't harmful, is safe and reusable.
The lamp works on a pulley system where a weight is raised up with a cord. Once it reaches the top, it is let go, and weight slowly goes down. As it descend, the cord passes through a connected train that lights a bright LED. Once down, rinse and repeat. Up to 30 minutes of light.
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