Grad student invents gravity lamp

A U.S. graduate student won second place in a "Greener Gadgets Conference" competition inventing a floor lamp powered by gravity.

Clay Moulton of Springfield, Va., who received his master's of science degree last year from Virginia Tech, created the lamp as a part of his master's thesis. The LED lamp, named Gravia, is an acrylic column a little more than 4 feet high. The entire column glows when activated by electricity generated by the slow, silent fall of a mass that spins a rotor.

The light output of 600-800 lumens lasts about four hours.

To "turn on" the lamp, the user moves weights from the bottom to the top of the lamp and into a mass sled near the top. The sled begins its gentle glide down and, within a few seconds, the LEDs are illuminated.

"It's more complicated than flipping a switch," said Moulton, "but can be an acceptable, even enjoyable routine, like winding a beautiful clock or making good coffee."

Moulton estimates Gravia's mechanisms will last more than 200 years.

A patent is pending on the Gravia lamp.

Copyright 2008 by United Press International

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Feb 19, 2008
think about the amount of effort you put into a windup radio or flashlight. 60 seconds of winding for 10 minutes to an hour of light (mechanical rotary motion) vs four hours of light for a simple bend and lift (potential energy transfer). So no, the lamp does not extract energy directly from the earths gravity field, but it is still "gravity powered". It is really just a name, I mean, does a lava lamp really have lava in it.

Also, the lamp was created as part of a Master's Thesis, not as the Master's Thesis. The Thesis could have been regarding a novel and efficient way to convert linear motion into electrical energy. I bet you could get a PhD for that in the EU.

Feb 19, 2008
dgbeach and nilbud, don't be such haters; he doesn't claim the energy comes from gravity (just the electricity generated does) nor does the article imply you can get a Masters degree for making a lamp. I think it's a novel idea and worthy of note.

Feb 19, 2008
"he doesn't claim the energy comes from gravity (just the electricity generated does)"

Who let an engineer in here?

Feb 19, 2008
The real credit goes to the people who have developed the new generation of LED technology that has such high output and efficiency. That said, this inventor has created a novel product from existing technology; one that has extraordinary possibilities for deployment in underdeveloped countries. It seems that very low cost versions of this could be used to bring light to villages with no electrical infrastructure. Remember, the cotton gin was a revolutionary invention made from such mundane materials that the patent was futile. Brilliant engineering can be found in many such inventions that leave us all smacking our foreheads saying, "Duh! why didn't someone (like me) think of that years ago?!"

Feb 19, 2008
I agree EAC. I doubt many people will have these things in their homes, but if they can be made cheap enough it would be great for out of the way places without their own electrical grids.

Things like camping trips, emergency lights during the extremely long power outages that sometimes accompany natural disasters like earthquakes or freezing rain (LEDs don't burn out, and it doesn't have batteries, which have expiry dates and need to be replaced every few years even if they are just sitting in storage, and those power outages can last for up two a couple months, even in developed countries. Just look at New Orleans or Quebec a few years ago), out of the way villages in third world countries, etc.

This makes a great replacement for those awful handcranks. I can't stand those things.

Feb 19, 2008
I'm just wondering how much energy it is necessary to spend for powering up the lamp. 600 lumens ~ 40w, if this is neon lamp, lets assume that it takes 40/5 =8w. 8w*4h=32WH or 115200WSec. From the other side we need to spend the same amout of mechanical energy. M*G*H, Where M - mass, G=9.8, H-high=1.5m. So M=115200/9.8*1.5=6530,6kg. It is about 6.5t or more than 13000 pounds. Even if the lamp is 100 times better than the neon lamp, - anyway, weight should be 130 pounds, -(without any energy losses), - is it possible?

Feb 20, 2008
They are recently developed low energy-usage LEDs mandarin.

Feb 20, 2008
i doubt its patentable, basics are common knowledge with loads of prior art

Feb 20, 2008
What will he come up with next a "gravity powered" watch maybe.

Feb 20, 2008
All being said, I DO think it is a very novel approach to produce would be a goldfish with a harness, turning a generator wheel, while trying to get away from a picture of a shark :)

Feb 21, 2008
Sounds cool, I'd buy one if looked nice.

Feb 25, 2008
The gravia lamp does not work.

From the CRC reference book:

1 watt = 680 lumens is the maximum effeciency possible for production of light energy.
Assuming the gravia lamp operates at one watt to produce the claimed 600 - 800 lumens makes for an estamate of how long the lamp can operate. Placing 25 Kilograms of mass at the top and having it fall through a distance of 1.5 meters makes less than 400 joules of energy. here is the calculation:

mass * acceleration * distance
= 25kg * 9.8m/sec^2 * 1.5 meters

This would allow the lamp to run for less than 400 seconds or about 6 to 7 minutes.

the claim that the lamp would run for 4 hours is a fraud.

Feb 27, 2008
The comment about gravity vs wind up technology is interesting. I wonder how well this sort of thing would scale up.

You could imagine a village in the third world with a large version of one of these masses, hoisted up to the top by several strong men and utilising pulleys to give a mechancal advantage.

Perhaps it could be used to light the village for the evening? Or maybe power the music system?

Some quantitative figures on devices that can run at low power would be interesting

Apr 02, 2008
Having read the Masters Thesis paper (which is very pretty), from which the Gravia Lamp concept was born, I have to question whether the architectural degree was awarded for artistic design qualifications rather than engineering design qualifications. Maybe things have changed in architectural design to such an extent that form is more important than function, and math skills are unnecessary. I call this the "if you can dream it, someone can build it" school of design.

There is virtually no engineering in the thesis paper. A committee, who obviously embraced the idea but had no understanding of the engineering limitations, endorsed the design concept. This is equivalent to proposing a design for an automobile that can take off and perform as an airplane while ignoring engineering details like required fuel capacity and engine size to achieve a desired range and load capacity.

All that said, I really do like the artistic rendering of the Gravia Lamp. Just add a power cord to plug it into a convenience outlet and forget the third-world villages. Perhaps the falling weight could still be used as an ON/OFF switch. In the thesis paper, removing just one of the five weights is supposed to stop the ball-screw mechanism from turning. If this were true, then the remaining four weights don%u2019t exert enough force to overcome friction in the mechanism. So, not only is it non-engineered, it is non-engineered in the worst way: it wastes over four-fifths or 80% of potential energy stored in the elevated weights! There is no explanation for why this was supposed to occur.

I recommend that everyone read the thesis paper here:

Apr 02, 2008
Oops! Looks like things do not translate well after cutting and pasting from MS Word...

I recommend that everyone read the thesis paper here (delete carriage returns between lines):


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