How Gravity-powered Floor Lamps Will Work

The idea of using the force of gravity to generate power has been around for some time. As far back as the 1970s, for instance, scientists were discussing the theoretical possibility of tapping into the gravitational pull of black holes to generate power [source: Time]. The idea was that if matter could be fired at a black hole from a safe distance (so the firing device wouldn't be sucked in), the extreme squeezing of that matter by the hole's gravity would make it hot enough to start a fusion reaction.

The Gravia lamp relies on a much simpler concept: Gravity pulls objects downward.

The lamp is a standing floor lamp, 58 inches (147 centimeters) tall and cylinder-shaped. Inside the cylinder, there are several basic parts involved in creating light: brass weights, a ball screw, a drive gear, a rotor, generator and a bunch of LEDs. Here's how the process works:

All of this happens over the course of four hours, and the LEDs, which light up a few seconds after the weights start to drop, remain on for that full period. They emit between 600 and 800 lumens, which is comparable to a typical 40-watt bulb [source: Dunn]. When the weights make it to the bottom of the lamp, the LEDs go out, and the person who started the chain of events has to input more power by moving the weights back up to the top of the screw.

Using gravity to light up LEDs is pretty amazing as it is. But the lamp has some benefits beyond being a conversation piece.

Any way you look at it, gravity as an energy source is hard to beat. It's free, it's in endless supply, and you don't have to import it, mine it, refine it or grow it. The very force that keeps you rooted to the ground could end up powering your house some day.

Since the Gravia lamp wouldn't plug into an outlet at all, it's about as "green" a gadget as you're going to find -- except maybe a solar-powered cell-phone charger or wind-powered tent lighting. The device is entirely self-contained, relying solely on human input to trigger the cycle that creates light. There's no outside energy required beyond that which goes into producing the lamp components in the first place.

And those components, according to the inventor, will never need to be replaced -- or at least not in a human lifetime. He estimates the lamp will work for 200 years [source: Dunn]. LED technology, on the other hand, is not quite to the point of the 200-year bulb. You'd have to buy new LEDs as they burn out. The state of that technology, in fact, is the reason why you can't actually go buy this lamp for your home.

In concept, the lamp is an award winner. In reality, it has a ways to go.

To generate enough power to light up those bulbs, the brass weights would have to weigh substantially more than a collective 50 pounds. They'd have to weigh about 2 tons (1.8 metric tons) -- a bit much for your typical human being to lift to the top of the lamp [source: Core77]. LEDs will have to become significantly more efficient before the Gravia lamp becomes a real possibility.

For more information on the Gravia lamp, gravity power and related topics, look over the links on the next page.