The idea behind the Gravity Light Project is both simple and inventive: produce a light that is powered by gravity.
While looking for an affordable replacement for kerosene lamps in Africa, Martin Riddiford and Jim Reeves broke their requirements down into two key components: the LED itself and the means of charging the light. As the actual light obviously had to stay, the two men focused their efforts on the issue of charging. Eventually, they hit upon the idea to use gravity and designed a battery-free light that harnessed gear ratios and potential energy; finally taking batteries out of the picture.
GravityLight: lighting for the developing countries from Therefore on Vimeo .
The Gravity Light is shipped in a heavy, durable bag that users fill with rocks or dirt to power a generator. Depending on how quickly the weights are allowed to drop, the power it generates is somewhere between 30 and 500 milliwatts. Small outputs are used to charge a lamp during the evening hours, while larger outputs can power small electronic devices.
http://www.indiegogo.com/projects/gravitylight-lighting-for-developing-countries
In much of the world, kerosene lamps are used to provide necessary illumination, but kerosene does a lot of damage to the people who use it. For instance, kerosene inhalation can do the equivalent damage of two packs of cigarettes a day. While in India alone, over a million people are burned each year by overturned kerosene lamps. Kerosene is also bad for the environment, eating up our limited reserves of fossil fuels and contributing to global CO2 emissions. Worst of all though, kerosene is quite expensive and can take up as much as 20% of an impoverished family’s income.
The Gravity Light works to resolve many of the issues related to kerosene lamps. Providing a safe, cheap and clean light should eliminate the larger healthy and safety problems; while offering an affordable light should allow farmers and students to continue their work after dark. In terms payback figures, the Gravity Light should even pay for itself within just three to six months (depending on the volatile cost of kerosene).
For those who’d like to know more, Martin and Jim regularly update their progress on the Gravity Light at deciwatt.org . Additionally, after a successful IndieGoGo Campaign in which they raised nearly $400,000, the team has garnered a lot of publicity. This includes getting featured on NPR’s Science Friday and the 2013 iteration of The CNN 10: Inventions article.
http://www.indiegogo.com/projects/gravitylight-lighting-for-developing-countries