Kerosene lamps have a certain romantic nostalgia, but for those who rely on these lamps as their sole source of light, they’re both dangerous and expensive. The fuel can cost 10-20% of someone’s income, and even the small flame contributes to high rates of disfiguring (even deadly) burns.
Much like an old grandfather clock, the GravityLight is powered by the force of gravity, pulling on a weight that a user has positioned. So a 22-pound bag of sand attached to a rope can generate 176 joules per lift, which is enough to illuminate a 100-square-foot room via LED for half an hour. There’s no battery backup, but that’s OK. Because when the time runs out, all someone needs to do is hang the bag of sand again. And sand is in pretty unlimited supply.
Indeed, when any gadget makes its way into a developing country, durability becomes of paramount importance. GravityLight is designed with such concerns in mind—the gears need no oil, they move very slowly and run dry, and the LEDs should have a 30–50-year shelf life—but working in an environment that’s often dirtier and hotter than the 72-degree vacuumed office spaces most of us spend our days, anything can happen.
From my limited knowledge of LED technology, it seems like a major concern will be, not how long the LEDs can last but how long they can last burning bright enough for practical use. (Heat destroys LEDs at the transistor level, even in cooler environments.)
