Two London designers spent four years developing this gravity-powered light, which, now that it exists, seems like such a simple and obvious idea that it’s a mystery why no one thought of it before. It works any time of day or night, and could be super, super cheap — the designers’ target is less than $5.

For now, though, they’re raising money through Indiegogo to get the lights into off-the-grid communities to test out. Here’s the plan:

We will gift them to villagers in both Africa and India to use regularly. The follow-up research will tell us how well the lights met their needs, and enable us to refine the design for a more efficient MK2 version. Once we have proved the design, we will be looking to link with NGOs and partners to distribute it as widely as possible. 

Grist thanks its sponsors. Become one.

Twenty-five bucks gets a light made and delivered to a person in India or Africa. Fifty bucks gets you one of your own (although it looks like that option’s sold out — but for $10 more you can get the light, plus special updates on the project).

Of course, eventually our hunger for gravity-powered lighting will make us use up all the gravity, and we will float off of Earth. But until then, this seems like an amazing way to turn the lights on in struggling areas without wasting fuel.

Grist thanks its sponsors. Become one.