Lamp Lit by Gravity Wins Greener Gadget Award
A Virginia Tech student has created an LED floor lamp that is powered by gravity, using a weight slide similar to the concept of a grandfather clock. The lamp puts out the equivalent of a 40-Watt bulb, and lasts four hours per cycle. The mechanism is expected to last 200 years.
Clay Moulton of Springfield, Va., who received his Master of Science in Architecture with a concentration in industrial design from the College of Architecture and Urban Studies in 2007, created the lamp as a part of this masters thesis. The LED lamp, named Gravia, has just won second place in the Greener Gadgets Design Competition as part of the Greener Gadgets Conference in New York City.
Concept illustrations of Gravia depict an acrylic column a little over four feet high. The entire column glows when activated. The electricity is generated by the slow fall of a mass that spins a rotor. The resulting energy powers 10 high-output LEDs that fire into the acrylic lens, creating a diffuse light. The operation is silent and the housing is elegant and cord free completely independent of electrical infrastructure.
The light output will be 600-800 lumens roughly equal to a 40 watt incandescent bulb. Each drop of the gravity mechanism runs the light over a period of four hours.
To "turn on" the lamp, the user moves weights from the bottom to the top of the lamp. An hour-glass like mechanism is turned over and the weights are placed in the mass sled near the top of the lamp. The sled begins its gently glide back down and, within a few seconds, the LEDs come on and light the lamp, Moulton said. Its more complicated than flipping a switch but can be an acceptable, even enjoyable routine, like winding a beautiful clock or making good coffee, he said.
Moulton estimates that Gravias mechanisms will last more than 200 years, if used eight hours a day, 365 days a year. The LEDs, which are generally considered long-life devices, become short-life components in comparison to the drive mechanisms, he said.
The acrylic lens will be altered by time in an attractive fashion, Moulton said. The LEDs produce a slightly unnatural blue-ish light. As the acrylic ages, it becomes slightly yellowed and crazed through exposure to ultraviolet light, he said. The yellowing and crazing will tend to mitigate the unnatural blue hue of the LED light. Thus, Gravia will produce a more natural color of light with age.
He predicted that the acrylic will begin to yellow within 10 to 15 years when Gravia is used in a homes interior room.
Learn more about the lamp and the designers philosophy at http://www.core77.com/competitions/greenergadgets/projects/4306/.
His masters thesis is here: http://scholar.lib.vt.edu/theses/available/etd-08292007-103115/
About the design competition
Greener Gadgets partnered with
Core77 to seek out design innovations for greener electronics. This competition
engaged established design firms, emerging designers, and design students to
come up with new and innovative solutions to address the issues of energy,
carbon footprint, health and toxicity, new materials, product lifecycle, and
social development. Top entries were showcased live at the conference by a
distinguished panel and the audience after two rounds of rigorous pre-judging.
Entries were evaluated on the following criteria: innovation, clarity of design,
originality, form, and presentation.
Physics Don't Support 40 Watts-Equivalent for 4 HoursOn February 20, 2008 2:17 PM, Mountain time; Mike Bentley wrote:
Some back-of-the-envelope calculations by a couple of engineers indicate that this clock is in no way capable of shining as bright as a 40 watt incandescent bulb. They're thinking, in fact, that you won't be able to get 4 watts.
The comments below come from a mailing list of consummate techies.
"They claim to be putting out 600 lumens for 4 hours by harnessing the energy in a 50 pound weight lifted about 1.5 meters. Anybody who's ever wished for a 600 lumen bike headlight powered by a hub dynamo is going to get suspicious at this point.
The most efficient LEDs on the market put out about 135 lumens per watt, I think. So they need at least on the order of 4 watts for 4 hours. That's 4 * 4 * 3600 = 57600 joules.
E = mgh
(I think the units here are joules, kilograms, m/s/s and meters - if
I'm wrong, everything below this point is useless)
Solving for mass,
m = E/(gh)
m = 57600 / (9.8 * 1.5) = 3918 kilograms
So you need to lift a 4000 kilogram mass 1.5 meters to run this for 4 hours, and that's assuming a 100% efficient generator. Either that or you need to lift the 50 pound mass 57600/(22.7*9.8) = 259 meters. Either way, you need something on the order of 175 times more energy than they have available.
Going at it a different way: 50lb is 22.7kg. At 9.8m/s^2 it exerts 222 newtons of force. A watt is a newton-meter, so this weight must descend 4/222=.018m/s to produce 4 watts. There are 14400 seconds in four hours. 14400*.018=259 meters."
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One February 21, 2008 5:59 AM, Inventor, Clay Moulton, responded to the above as follows:
Good morning Mr. Allan,
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Just Theory -- And Not Very Good at That
On March 4, 2008, Ray wrote:
The Gravity Lamp is a theoretical concept. It does not actually
exist. As per current LED