GravityLight: the low-cost lamp powered by sand and gravity

The problem of bringing light to remote parts of the developing world has been tackled in the past with everything from solar-powered lamps to wind-up devices and rechargeable batteries – all of which require relatively expensive kit or physical effort by the user. But two London-based designers have now developed a light source that operates on the stuff that surrounds you – earth, rocks or sand – with the helping hand of gravity.