Often the best creative ideas and the most elegant solutions are the simplest. GravityLight is an example of this type of innovation. Here’s the problem: replace damaging and expensive kerosene fuel lamps in Africa with a less harmful and cheaper alternative. And, the solution:

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[div class=attrib]From ars technica:[end-div]

A London design consultancy has developed a cheap, clean, and safer alternative to the kerosene lamp. Kerosene burning lamps are thought to be used by over a billion people in developing nations, often in remote rural parts where electricity is either prohibitively expensive or simply unavailable. Kerosene’s potential replacement, GravityLight, is powered by gravity without the need of a battery—it’s also seen by its creators as a superior alternative to solar-powered lamps.

Kerosene lamps are problematic in three ways: they release pollutants which can contribute to respiratory disease; they pose a fire risk; and, thanks to the ongoing need to buy kerosene fuel, they are expensive to run. Research out of Brown University from July of last year called kerosene lamps a “significant contributor to respiratory diseases, which kill over 1.5 million people every year” in developing countries. The same paper found that kerosene lamps were responsible for 70 percent of fires (which cause 300,000 deaths every year) and 80 percent of burns. The World Bank has compared the indoor use of a kerosene lamp with smoking two packs of cigarettes per day.

The economics of the kerosene lamps are nearly as problematic, with the fuel costing many rural families a significant proportion of their money. The designers of the GravityLight say 10 to 20 percent of household income is typical, and they describe kerosene as a poverty trap, locking people into a “permanent state of subsistence living.” Considering that the median rural price of kerosene in Tanzania, Mali, Ghana, Kenya, and Senegal is $1.30 per liter, and the average rural income in Tanzania is under $9 per month, the designers’ figures seem depressingly plausible.

Approached by the charity Solar Aid to design a solar-powered LED alternative, London design consultancy Therefore shifted the emphasis away from solar, which requires expensive batteries that degrade over time. The company’s answer is both more simple and more radical: an LED lamp driven by a bag of sand, earth, or stones, pulled toward the Earth by gravity.

It takes only seconds to hoist the bag into place, after which the lamp provides up to half an hour of ambient light, or about 18 minutes of brighter task lighting. Though it isn’t clear quite how much light the GravityLight emits, its makers insist it is more than a kerosene lamp. Also unclear are the precise inner workings of the device, though clearly the weighted bag pulls a cord, driving an inner mechanism with a low-powered dynamo, with the aid of some robust plastic gearing. Talking to Ars by telephone, Therefore’s Jim Fullalove was loath to divulge details, but did reveal the gearing took the kinetic energy from a weighted bag descending at a rate of a millimeter per second to power a dynamo spinning at 2000rpm.

[div class=attrib]Read more about GravityLight after the jump.[end-div]

[div class=attrib]Video courtesy of GravityLight.[end-div]