For many of us our entire understanding of gravity starts and end in physics class, but for some, gravity may just be the key to solving the Africa’s electricity problem. By Combining kinetic and potential energy, the great minds at GravityLight works have discovered that by connecting an elevated weight — filled with rocks or sand — to a pulley system, you can slowly power a generator as the weight falls to the ground.
Fascinating stuff right?
A simple procedure for this is already being applied in rural African communities like in Kenya. The procedure involves installing a 6ft/ 1.8m drop of a 12kg weight. This weight is lifted and on release starts falling very slowly (about 1mm / second). This movement powers a drive sprocket, which rotates very slowly with high torque (force). A polymer gear train running through the product turns this input into a high speed, low torque output that drives a DC generator at thousands of rotations per minute.
This generates just under a tenth of a watt, a deciwatt, to power an onboard LED and ancillary devices. Given the ever-increasing efficiency of LEDs, this produces a light over 5 times brighter (lux) than a typical open-wick kerosene lamp. Once the weighted bag reaches the floor, which depends on how high it was installed, it is simply lifted to repeat the process.
This simple technique is somewhat similar (yet quite distinct) to hydroelectric power generation which also utilizes relative motion to power turbines which in turn generates power.
The gravity light project which is in conjunction with Shell’s Make the Future program is a unique small scale alternative power solution that is already being used in Kenya. It os also noteworthy that the GravityLight Foundation is a UK Registered Charity working to alleviate poverty and protect the environment through innovative design.