Gravity Lamp Grabs Green Prize 596
eldavojohn writes "A lamp powered by gravity has won the second prize at the Greener Gadgets Conference in NYC. From the article, "The light output will be 600-800 lumens — roughly equal to a 40-watt incandescent bulb 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 gentle glide back down and, within a few seconds, the LEDs come on and light the lamp ... Moulton estimates that Gravia's mechanisms will last more than 200 years, if used eight hours a day, 365 days a year." The article contains links to the patents and the designer/inventor Clay Moulton's site." I think my laptop would require a slightly larger weight to pull this off.
gravity powered? (Score:2, Informative)
!perpetual motion machine (Score:2, Informative)
Re:A patent? (Score:3, Informative)
Re:Home Gym.. (Score:1, Informative)
http://www.core77.com/competitions/greenergadgets/projects/4306/greener_gadgets_03.jpg [core77.com]
And it runs for four hours, too. (Score:3, Informative)
Four hours is an awesome run-time for such a device.
I lived in a house once where the land lord had a wind-up radio. It was great in every respect other than its run time; every fifteen minutes or so you had to crank it up again, which made it annoying to use.
-Fl
Re:Bigger Weight? (Score:3, Informative)
That's not how the electricity is being generated, rather it is coming from a rotor system.
There would be no functional difference between one 50 pound weight and 5 10 pounds weight, other than in resetting the system.
It can't possibly work either (Score:5, Informative)
The red led on the front of your modem requires around this amount so the glow will be feable. To get the equivalent of a filament 40W bulb requires around 10W so the system is only around a factor of 1000 out.
Re:Home Gym.. (Score:3, Informative)
Re:Doesn't check out. (Score:5, Informative)
Given that LEDs emit about 100 lumens/watt, that's say, 6 watts, * 4 hours = 86,400 joules They claim it's about 2m high.
Plugging those two values into the gravitational potential energy calculator at http://hyperphysics.phy-astr.gsu.edu/Hbase/gpot.html [gsu.edu] gives a weight of about 5000kg, slightly above the claimed 22kg...
Physics for designers (Score:5, Informative)
There's 50lbs of weight that fall about 4ft, if I'm reading the diagrams right. That's 200 ft-lbs. Which comes out to... hmm... 0.075 watt-hours. Over 4 hours that means 0.019 watts continuous power. From memory really good blue LEDs are around 200 lumens/watt so
To get ~700 lumen light at 200 lumen/watt would require 3.5 watts of power, over 4 hours is 14 watt-hours or 3700 ft-lbs. Over 4ft of fall that amounts to 925 lbs. My goodness, that is a group effort.
Re:It can't possibly work either (Score:5, Informative)
The red led on the front of your modem requires around this amount so the glow will be feable. To get the equivalent of a filament 40W bulb requires around 10W so the system is only around a factor of 1000 out.
Your conclusion is right, but your figures are a bit out. The drop is 58" according to the plan [core77.com]. This gives about 0.022W at 100% efficiency.
For reference, the highest efficiency LEDs that I know of get 131 lumens per watt. If we're generous and allow them 150 lumens/watt, they still need 4W of power. This would require a drop of 255 metres using the 50lbs of weights he claims. Since we can't really go above 1.5m high, we'll need almost 4 tonnes of weights.
A shame really, I'd have rather liked one.
Re:These numbers look worng (Score:3, Informative)
I'm replying to my own email. Sorry!
550 lbs over an hour will yield the numbers I posted. 55 LBS will yield 1/10 of the above.
He doesn't have 10.34 watts. He has (50/550)/3600 = 2.5253E-5 HP * 745 = 0.019 watts.
This won't provide much light.
550 lbs dropping 20 feet in 1 hour is (550/550)*20/3600*745 = 4 watts for an hour.
Re:!perpetual motion machine (Score:4, Informative)
Force x Distance/Time=W
22.6Kg x 1.47m x (9.8m/s/s)/14400s =
A brushless motor can operate at up to 90% efficiency, but the friction in the system will reduce the efficience a lot. We'll just say it runs at 60% efficiency. That's just 13.5mW. You need five of these to power an LED under current configuration. They want 600-800 lumens. So we'll lowball the figure with 600. Each LED can do about 80 lumens.
600/80=7.5, so 8 LEDs. That's 400mW of power for the system, or 30 generators.
Either you need 30 generators, a 680Kg weight, a 44.1m tall light (falling 30x's faster), OR a planet with 30x's the gravity. Your call.
Re:Why not use a spring? (Score:4, Informative)
I think part of the beauty of the mechanism is that it's really robust and long-lasting.
Just thinking about how you could build such a thing, I bet you could make a machine that had multiple ways of recharging/resetting it. My thought would be to have a lightweight 'sled' with a heavy removable weight on it. When the heavy weight is removed from the sled, a very small counterweight pulls it back up to the top of its track, so you can place the heavy weight back on. That's one way of resetting it, and the easiest provided you could pick up and lift the weight at once. The alternative would be to put a small crank on the sled's counterweight wire, which would allow you to slowly crank up the sled, with the counterweight on it. You'd end up doing the same amount of work but with a much smaller amount of force, due to the mechanical advantage of the crank.
That arrangement completely avoids using springs (it would only use counterweights) and would probably last a long time. I'm not sure whether it would be long enough to build some sort of 'Clock of the Long Now'-type device, but it would probably last a few human generations.
Re:!perpetual motion machine (Score:4, Informative)
Re:It can't possibly work either (Score:5, Informative)
And exactly how does having a screw generate more energy?
The path the weight takes to the ground is irrelevant.
An object weighing X lifted to a height of Y meters generates has a certain amount of potential energy, regardless of the path taken to the ground.
Re:Looks cool... (Score:5, Informative)
because it cant be made. You have a better chance at making cold fusion work or a perpetual motion machine than making this lamp do what was claimed.
first, there is no way for them to make enough energy even assuming 100% conversion to generate the electricity needed to power even 1 led for enough light to match that of a book light, many others here have covered this fact already..
Secondly the designer made HUGE mistakes in assumption is is a fact being missed by everyone else here debunking it.. Led's when rated in lumens are rated in their very narrow beam pattern, when you fire it into a lens/reflector to disperse the light to get an area lighting effect that his lamp is going for the lumens drop logarithmically. to go from the 15Deg beam pattern the LED's lumen output is measured at to a 270 degree pattern you will lose about 80% of the lumen output level.
So to get The claimed output, the device needs to generate a SHITLOAD more power, or increase the weight to be near 900 pounds or only operate for a few seconds at a time.
In other words, it does not work, cant work, and will never work. I think the guy is waiting for the laws of physics to be broken for his lamp to work.
I have been working with a company that designs LED lighting systems and most everyone get's confused because ratings on LED's are all over the road and not measured the same way as other lamp technologies.
This lamp if it used CFL lamps would have a far better chance at makign the claimed Lumen output than with LED's led's are still far-far less efficient than CFL lamps when it comes to area light output in beam widths wider than 20 degrees.
Thermal instead of potential energy recovery (Score:3, Informative)
http://www.eere.energy.gov/consumer/your_home/water_heating/index.cfm/mytopic=13040 [energy.gov]
http://www.gfxstar.ca/specifications.htm [gfxstar.ca]
As pointed out by some other posters, kinetic or potential energy recovery might lead to the nasty problem of clogged pipes, but thermal energy recovery doesn't have that problem.
Re:It can't possibly work either (Score:3, Informative)
Re:Why not use a spring? (Score:3, Informative)
Uh, I'm pretty sure they are still used most of the time even with automatic doors. Those chincy little motors couldn't lift the full weight of a wooden garage door, nor could their mountings handle it most of the time. The spring is still there, and is still doing most of the work. Certainly at least when the spring broke on my old house's garage door, it wasn't going anywhere manually or via the automatic opener.
Anyway, your point about the longevity of springs is correct.
Re:It can't possibly work either (Score:3, Informative)
OK, let's go back to physics 101. The device has stored a certain amount of potential energy when the weight is on the top, and a lower potential when on the ground. That's all there is, that's all the energy you can transform into light. Nothing can change that. The only effect (besides added friction) of making it spin around is that you stretch the time in which you make use of the energy. Result: less light, but over a longer time period.
Not that it would even be a bright light if the weight would go straight down...