British designers are using the power of gravity to generate electricity, bringing safe and affordable light to people living off-grid. The kerosene that fuels most off-grid lamps is very expensive. Kerosene is also dirty and dangerous. In 2009 ... designers Martin Riddiford and Jim Reeves were challenged to create a safe, affordable, and sustainable lamps for low-income families living off-grid. Looking beyond solar and battery power, they had a lightbulb moment about gravity. Lifting a weight creates a potential energy store which is turned into kinetic energy as the weight descends. Through the GravityLight's innovative gear train, this kinetic energy spins a generator that produces enough electrical energy to power an LED bulb. When the light goes out, the weight is simply hoisted back up to begin again. GravityLight has been piloted in Kenya where kerosene lamps are used extensively, especially in rural areas. A 50-night roadshow, supported by International celebrities, saw GravityLight engage with communities and organizations across the country. The results were impressive, with 90% of people saying they were happy to switch from kerosene. Little wonder, as the benefits quickly stack up. The GravityLight pays for itself in just seven weeks, and delivers an immediate improvement in the air quality of the home. It is clean, robust, renewable, reliable, and safe-as well as being better for the environment, giving off no CO2 or black carbon emissions.