The simple notion of using a slow-moving, falling weight to power things has been around for centuries. Think big clocks in 16th century cathedrals.
So when I saw the principle applied to an LED lamp, my first thoughts were about lighting for either off grid emergencies or off grid emergencies or lifestyles.
Using 26 pounds hung six feet above ground, the GravityLight provides 20 minutes of light. Over and over and over again. In the words of the design team:
Once GravityLight is installed and a 12kg weight – a bag of rocks or sand – attached, it’s ready to go, anytime.
The weight is lifted by pulling down on a bead cord. On release, the weight falls very slowly, transforming potential energy into kinetic energy as it powers a drive sprocket and polymer gear train.
This generates just under a tenth of a watt, to power an onboard LED and ancillary devices.
Once the weighted bag reaches the floor, which depends on how high it was installed, it is simply lifted to repeat the process.