GravityLight is a gravity-powered lamp designed by the company Deciwatt for use in developing or third-world nations, as a replacement for kerosene lamps. It uses a bag filled with rocks or earth, attached to a cord, which slowly descends similar to the weight drive in a cuckoo clock. This action powers the light for up to thirty minutes on low power. The device can also be used to charge other devices.
There are no operating costs after the initial purchase of the appliance. A standard GravityLight kit comes with an adjustable lamp and a ballast bag. The light can be turned on by filling the bag with approximately 20 pounds weight[10] (10 kg) and lifting it up to the base of the device; the weight falls over a period of 25 minutes, pulling a cord/strap that spins gears and drives an electric generator, which continuously powers an LED.
The second model, GL02, also includes two SatLights and connecting cables. These are separate lights that are wired in series from the main GravityLight unit. Each SatLight can be turned on or off separately. When used with SatLights, the light on the main unit can be turned on or off. Up to 4 SatLights can be connected, giving extra light to different locations in the house. The rate of the bag drop is almost not affected by the number of SatLights attached. While the original GravityLight used a strap for pulling up the weight. The improved GL02 used a plastic-bead chain on a pulley system. The pulley system requires less strength to pull up.
Siemens Stiftung – the foundation arm of Siemens that promotes sustainable social development – will help roll out the UK-designed system to to over 15,000 people without electricity by 2017. It has already won a £200,000 grant from the UK Government and £400,000 through crowd-funding site IndieGogo.
As of December 19, 2016, GravityLight is being produced in Ruiru, Kenya. They produce 140 per day.
