Even though many of us take for granted the point that we can just hit a switch and be flooded with non-natural light, nearly one billion people in the world still have no access to electricity at all. This clearly means a lot of people are depending on unsafe and expensive kerosene lamps to provide them with light to study, cook and work after dark. But a group of engineers from the UK has now made a new device called GravityLight that runs purely using the force of gravity. The set-up is quite easy to understand, the whole thing works a little like a pulley - all you need to provide a 12 kg of weight to one end of the bead cord (this can be a sack of sand, rocks, whatsoever you like), and then simply lift that weight up by pulling down on the lamp attached to the other side. Due to gravity, the weight gradually inclines back down to the floor, converting potential energy into kinetic energy as it descents. This kinetic energy then powers a drive sprocket and polymer gear train that lights up the LED as it goes.
Once the weight touches the floor, the light goes out and you need to repeat the procedure, but each pull delivers around 20 to 30 minutes of light, depending on how high you lift the weight up. The group of engineers is now crowd-funding the second version of GravityLight on Indiegogo, with the expectation that they can get US$199,000 in order to make their light brighter, long-lasting and easier to use. GravityLight will only cost around US$10. This is a whole lot inexpensive than kerosene lamps, which not only pose a high fire danger and spew out chemicals, they also burn through about 30% of a family's income, according to the GravityLight group. GravityLight will be firstly targeted to families in developing countries, with a primary focus on Kenya, and the group is hoping to deliver local jobs by producing and selling the lights over there.
Obviously, the best thing about gravity is that it's free, so once the initial investment has been made, the lights factually cost nothing to run.
H/T to Gizmodo