Any time someone announces a “new source” of renewable energy, there is reason to be skeptical. That especially holds true if they go on to claim that the energy source is “free.”

There is no such thing as a perpetual motion machine.

Energy has to come from somewhere, and there are few truly original ideas under the sun.

Nevertheless, I was struck by an NPR news piece reporting on inventors who have created a lamp powered entirely by gravity.

Cheaper than a solar lantern

Gravity LightBuilding on a movement that has seen solar lighting proliferate in poor rural communities around the world, a British industrial design company called therefore had been working on low-cost, low-power devices for poor communities under the project title of Seeking to further cut costs on low-cost solar lighting, the team’s inventors — Martin Riddiford and Jim Reeves — realized they could radically slash equipment costs by eliminating the need for a battery altogether.

GravityLight was born.

The light features a small generator; a bag that is weighted with sand, rocks, dirt or whatever materials are close at hand; and an LED lamp. Users then hang the light from a convenient height, and generate a trickle of up to 30 minutes of usable electricity through the simple action of lifting the weighted bag and letting it slowly descend.

Ease of use

Not only does the design reduce the cost of lighting to as little as $5-$10 per unit, the inventors believe that it will also provide significant user benefits over devices that require either unpredictable and intermittent sunlight to recharge, or a sustained physical effort like turning a hand crank. The GravityLight, by contrast, requires one swift motion, followed by a predictable and prolonged output of power.

Currently in the prototyping stage, Riddiford and Reeves turned to a crowdfunding model to make their project happen. Through IndieGoGo, their campaign raised almost $400,000 — or 727 percent of their original target.

The inventors could hardly conceal their excitement, as evidenced by a post on their website:

“Wow. After 40 amazing days the campaign has now closed. We want to extend our heartfelt thanks to all of you who have helped us. Rather than using our time to individually respond to all your inspiring comments, we’ve been getting on with the main job in hand. No offence. We are working flat out to complete the production specification and already have the second tranche of tooling underway with our supplier in China.”

As Riddiford told NPR, the challenge now is not just to produce the light but to refine each element and utilize economies of scale to bring the costs down. The team will also be collecting ongoing data from field trials in Africa to understand how the light is used in the real world.

Battery-free Internet access?
The unit can already be adapted to power task lighting or charge batteries, but the development team is looking at the possibility of developing a battery-less system for accessing the Internet. Riddiford calls this ambitious goal for the system a “long shot,” given the power budget available, but Riddiford and colleagues have so far proven themselves adept at pushing the envelope of what’s possible with just a little imagination and a tiny amount of electricity.

Here’s the IndieGoGo video explaining how it all got started:

Read about other innovators and ideas at The Leaderboard. If you have a story suggestion for this year-long project, please contact us.

Related stories on MNN:

What is GravityLight? A $5 battery-free lamp for the poor
Inventors Martin Riddiford and Jim Reeves realized they could eliminate the need for a battery if they relied on the power of gravity.