Lamp uses energy from falling weight to illuminate homes without electricity.
- GravityLight may help 1.3 billion people who live without electricity supply
- When hung from a ceiling the device can produce light for 20 to 30 minutes
- It uses a falling 26lb weight to turn a generator that powers an LED lamp
- Two satellite lamps can be attached that can be hung over a desk or bed
It sounds like something more akin to alchemy, but engineers have developed a new light powered by gravity.
The GravityLight is aimed at helping the 1.3 billion people who live without electricity in areas of the world too remote or poor to have a reliable grid.
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 device means families can replace their dangerous kerosene lamps that are common in many parts of the world to light activities after dark.
These lamps use naked flames and can produce harmful fumes.
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.
Mr Reeves said: ‘One in five people don’t have access to electricity.
‘For families living on just a few dollars a day, kerosene lamps can consume up to 30% of their income creating an ongoing poverty trap.
‘With GravityLight, all you need is a weight.’
The team have already tested their prototype GravityLight in 1,300 homes in 27 different countries.
HOW THE GRAVITYLIGHT WORKS
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).