The light powered by GRAVITY: Lamp uses energy from falling weight to illuminate homes without electricity
It works using a pulley system where a weight can be fixed at one end and as it drops the force drives a generator through a series of low torque gears.
The generator produces just under a tenth of a watt which powers an LED light on the unit itself and two smaller satellite lights that can be hung over a desk or bed.
The designers of
GravityLight claim that with a 26lb (12kg) weight it is possible to provide between 25 minutes of light if installed at a height of six feet (1.8 metres).
Jim Reeves and Martin Riddiford, who are based in London, invented the device.
They point out that unlike devices that rely upon solar energy to provide power to remote communities, gravity does not disappear at night.
The device is installed to the ceiling of a room and a bag filled with around 26ft (12kg) of rocks or sand is attached to a cord that runs through the unit.
A beaded cord running through the unit allows the weight to be lifted into the air and it then falls slowly to the ground.
A system of gears and a generator inside the device convert the kinetic energy released by the bag as it falls under the influence of gravity into electricity.
Once the bag reaches the ground it can be raised back up to the ceiling to produce more power.
The energy produced can be used to power the light and other devices attached to a DC power outlet.
The generator produces just under a tenth of a watt which powers and provides between 20 to 30 minutes of light if installed at a height of over 6ft (1.8 metres).
The GravityLight comes with a bag that can be filled with sand or rocks to provide the weight needed to power it
