Gravia: LED Lamp Lit by Gravity Lasts 200 Years, Never Plugs In
by Collin Dunn, Corvallis, OR, USA on 02.21.08
When we talk about going off-grid, or otherwise unplugging from traditional power sources, it usually involves solar or wind power, or some other alternative that doesn't involved your local utility. Young designer Clay Moulton has figured out how to harness a different source to create electricity: gravity.
"Gravia" is his LED-lit floor lamp that combines human power and gravity to create a lighting source that will work for 200 years or so, and never need to be plugged in. The lamp has a weight that's raised every four hours or so; as it slowly descends, the downward motion is converted to torque via a high-efficiency ball screw. The torque is overdriven (at 1:160 for those of you scoring at home) by a harmonic drive gear hand, and the output from that spins a set of 12 high-strength neodymium magnets (which act as the rotor), spinning to power 10 high-output LEDs. Simple, no?
Gravia's light output of 600-800 lumens is roughly equal to a 40 watt incandescent bulb is all thanks to this slick system, which recalls hourglass-like timekeeping; every four hours or so, the process starts again with a little help from human power, and it's probably worth a little lifting to keep it going: Moulton has calculated that, with 8 hours of use 365 days a year, the lamp will last for more than 200 years, and will only get better with age.
The acrylic lens will be altered by time in an attractive fashion, Moulton says. “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.”
The design, part of his master’s thesis at the College of Architecture and Urban Studies in 2007, recently won him second prize at the Greener Gadgets Design Competition (watch a video of the winners for more), which was a ton of fun, if our video wrap was any indication. Now that gravity power has come down from the stratosphere, we'll look for more concepts that put it to good use. ::Greener Gadgets Design Competition at Core77 via ::Sawf News and ::DVICE
According to this website, the young inventor concedes that there was an error in his calculations and that the lamp may not be able to provide as much wattage as stated in the original post.
Very cool. I'd love a reading lamp that works on that principle.
quick - lets get this technology into a small device charger. 4 hours - sounds perfect.
Well, isn't that something. Is it expensive?
There was a discussion about this on slashdot,
and apparently this concept cannot emit as much light as advertised...
It will emit 1000 times less light....
i think this is very cool. something smaller, in a reading or desk lamp would be awesome. the timing could be 30 minutes or so, instead of 4 hours. if you're still sitting there, needing it, just set it to going again.
could even make a 15 minute one to be used as a child's night light. when the child falls asleep, the light will go out. no needing to remember to switch it off.
This sort of electrical generator wouldn't be difficult to make. Put a weight on a cord, wrap the cord around the shaft of an appropriately sized DC motor, let go. For the most part, by "shaft" I mean an appropriately geared transmission, because you'd need to add a fair amount of resistance to keep the weight from accelerating to the floor.
They actually used to use this method for powering clocks.
I think there would be a market for using it as a back-up emergency light if the cost isn't too hight. Even the off-grid people would love it for clouding no wind days.
This is a great story, but it's simply impossible. Physics and current lighting technologies just don't permit it. Check the Slashdot discussion for the relevant math (http://hardware.slashdot.org/article.pl?sid=08/02/20/1446256). Note that some of the posters are, well, not entirely correct in their calculations either.
If anyone had actually bothered to build this device, or even run some basic math, before giving it an award they'd realize this. Can we stop giving awards to mere concepts?
If not, I have a concept for a lovely little ring. You wear it, and it makes you not need any food or air, while simultaneously making you feel more energetic and happy. Please give me an award for saving the planet.
I apologize for the sarcasm, but this sort of thing hurts environmentalism more than it helps by making us look like a bunch of innumerate airheads. I don't blame the "inventor" as much as I blame the people who acclaimed him. Talk about missing the forest for the trees.
"Natural color" light meaning that of an incandescent light bulb, I assume. Nor really very natural, unless referring to candlelight.
This is my new favorite thing. If there isn't enough light, just get a heavier weight and re-gear it. C'mon kids, help your old man turn on the light!
Assuming the bulb needs about 12 watts of energy output would equal 48-watt hours or 172800 watt-seconds. 1watt = 1 joule/second, therefore, we need 172800 joules of energy total to power it for 4 hours. If we assume a drop of 1.5 meters, around 5 feet, we can calculate the weight needed for the energy output.
Potential Energy = mass * gravity * height
172800 joules (kg * m^2/s^2) = mass * 9.8 m/s^2 * 1.5 m
solving for the mass, we get 11755 kg, or 25861 pounds, not allowing for frictional losses...
I agree with M. Anderson above - the science is very basic and had the designer put some thought into the actual feasibility of his invention, then perhaps a better solution would have come about. I am oftentimes disappointed with how little science knowledge many "environmentalists" have. Whenever a new piece of green information comes out, we should all try to find out whether it's feasible or not. Having only hope will get us nowhere.
science issues aside, plannign on the yellowing from exposure to uv wont' do much since phosphors are targted to the color of led you want.... there are oodles of warm white LEDs atm, although a better solution would be a mix of colored leds to give a balanced light....
>11755 kg
That's not an obstacle. We're going to make the action from neutronium.
"The acrylic lens will be altered by time in an attractive fashion"...
While that might produce a "warmer" color-temperature, it would also lead to fewer lumens being produced... the human eye is more sensitive to light at a color- temperature of 5500K (the color light it produces originally) than to a color-temperature of 3000K (a typical incandescent bulb).
Interesting concept overall, but for the time being, the best way to green your home is to switch to the low power LED lights that are already out there. Lots of them run on 3watts or less, so switching to those LEDs is a great first step.
To learn more about some of the better available LED lights check out the link below.
http://weloveleds.com/
www.ledlight.com
much better prices. I've gotten their 36led dome lights, the 18led dome's to replace my fridge/freezer lights, par38's for the ceiling cans and that giant hedgehog bulb for a standing lamp.
I tend to disagree with Brandon's calculation. All you have done is calculate the potential energy in the MASS, not the system. For the system, you have to integrate the ball screw, gearing, rotor/stator (and anything else in the system) to get the correct mass needed to drive the system. Even if your mass calculation were close (which it isn't), a gearing of 1000:1 would make it a 11.755 kg mass needed. I can make a gearing of 1000:1 using a basic LEGO set!
Everyone should remember that the exact same principle has been used to power clocks for hundreds of years and that's with a bob of say 250g (on my grandmother's cuckoo clock) can power it. So why is it so hard to believe that by increasing the mass to say 5 or 10kg you couldn't power some low power LEDs? Or even a series of smaller bobs, maybe 4 x 2.5kg ones. With 4, you could choose the lighting level you wanted by only raising the number of bobs you wanted!
Anonymous: gearing cannot create energy. If you geared it 1000:1, you might only need 11kg, but you would need a 4000 foot drop. Powering a little clock and creating 600+ lumens are different orders of magnitude.