Cannes Lions

GravityLight: turning gravity into light


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Powered by the lift of a weight, GravityLight is an innovative device that provides instant, limitless light. It takes seconds to lift the weight – a bag of rocks or sand – and provides 20 minutes of light on each decent. With no need for batteries, charging or the sun, GravityLight provides a universal, year-round solution.

GravityLight has no running costs and pays for itself within four months of replacing a kerosene lamp. This alleviates a significant financial burden and frees up money to be spent on other important costs, such as school uniforms or investing in family enterprises.

As part of the #MakeTheFuture campaign, we spent 50 nights in 50 Kenyan communities working with the GravityLight Foundation, demonstrating GravityLight to thousands of people. We showed them how to use the lights, and the many benefits they bring. Thousands of people supported us on Facebook, Instagram and YouTube.


GravityLight utilises kinetic energy; a user simply lifts a weight and this powers one main light and up to two ‘sat’ lights for twenty minutes on each descent.

More specifically, GravityLight is installed to provide a 1.8m drop for a 12kg weight. This weight is lifted and on controlled release starts falling very slowly. This movement powers a drive sprocket, which rotates very slowly with high torque. 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 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 completes its descent, it is simply lifted to repeat the process.


Targeted mainly at the rural poor using kerosene lamps and urban poor using kerosene and unreliable grid power, anticipated outcomes are:

• Environmental - GravityLight Foundation’s mission is to significantly reduce the use of kerosene lamps, decreasing CO2 and black carbon production, replacing them with a clean, renewable energy source;

• Alleviating the poverty trap caused by the cost of kerosene, freeing up money for other priorities;

• Creation of jobs and skills through the marketing and distribution of GravityLight in Kenya (our pilot market), and then East Africa. GravityLight was featured on important global media such as CNN, BBC, Mashable, Popular Science, Forbes, Time, Wired, Fast Company, Bloomberg, Fast Company, The Telegraph, AlJazeera, Reuters and dozens more. Bill Gates tweeted about GravityLight, “a pretty cool innovation which could be a source of cheap light in developing markets”.

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