Innovation

For Homes Without Electricity, a Lamp Powered by Gravity

by Aarian Marshall

August 25, 2015

What’s more plentiful than sunlight? Most have heard of solar energy, an important, plentiful, and often cheap energy source for the 1.3 billion people who live without electricity.

But a new project turns to another vital and often overlooked resource: gravity. Introducing GravityLight, a technology first presented in prototype in 2012 but now getting ready to roll off the assembly line in Kenya after a successful Indiegogo campaign.

"We wanted to make a device that could provide power for light, as and when it was required, with no limit to the run time in any given night, at a price that will be affordable," GravityLight co-founder and designer Jim Reeves told Co.Design.

The newest edition of the GravityLight comes in at a relatively pricey $20, but Reeves says the light will pay for itself within a few weeks. That’s because the light could replace a more expensive lighting method often used in developing countries: the kerosene lamp. The World Bank estimates that those living without electricity spend a whopping $36 billion on kerosene lamps each year—about 10 to 30 percent of total annual income per household.

Kerosene lamps are also dangerous. Inhaling kerosene fumes can lead to lung and heart problems. And kerosene lamp accidents severely burn 1.5 million people each year in India alone.

The science behind GravityLight is simple. The light comes equipped with a gear train, a DC generator, and an LED light. The user must hang the product at least six feet in the air, and attach a 25-pound weight (which can be as no-frills as a bag of rocks and sand). Then gravity does its work: The weight falls at a rate of 0.04 inches per minute, powering the gear train and generator, and illuminating the powerful LED light.

Voila: about 25 minutes of brightness, depending on how high in the air the light has been installed. And when the light goes out, users just suspend the weight in the air once again. 

Correction: This post has been updated to clarify that a GravityLight powers an LED lamp for about 25 minutes per weight suspension.

All images via GravityLight.

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For Homes Without Electricity, a Lamp Powered by Gravity