# Gravity Light



## C-Dog (Feb 27, 2008)

I have to get one of these...

It uses gravity (PE=mgh) to produce electricity and power a LED light...

GRAVIA



> Called Gravia, this lamp is made of an acrylic column a little over four feet high. Designed by a student at Virginia Tech, 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 ten high-output LEDs that fire into the acrylic lens, creating a diffuse light. The light output is 600 to 800 lumens - roughly equal to a 40-watt incandescent bulb over a period of four hours.


Now that is outside the box thinking!


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## Sschell (Feb 27, 2008)

My favorite part of the article is the begining



> While many people want to know when the lamp will be available, many others point out that it won't actually work



the designers responce is great designer babble



> I hope everyone understands that this criticism and even failure is all part of a process, and that my job as a designer is to take this feedback and work on.


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## Dleg (Feb 27, 2008)

So it's not actually gravity powered, but user-powered: The user "activates" it by sliding the weight to the top of the column.

Calling this thing "gravity powered" is akin to advertizing a glider as "a revloutionary, gravity-powered aircraft!"


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## FusionWhite (Feb 29, 2008)

Dleg said:


> So it's not actually gravity powered, but user-powered: The user "activates" it by sliding the weight to the top of the column.
> Calling this thing "gravity powered" is akin to advertizing a glider as "a revloutionary, gravity-powered aircraft!"


Its less "user" powered then it is an energy conversion. You supply potential energy by lifting the thing, which then uses gravity to produce kinetic energy which is transfered to mechanical energy and finally light. Yes it requires you to input the initial PE but it takes it from there.


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## EM_PS (Feb 29, 2008)

:huh:

Just spitballin' here - what if the mass, as it descends, pulls a slightly lesser mass up. When said masses reach their terminal descents / ascents, the upper mass would 'dock' with a weight plate, making it the heavier mass, thus pulling back up the primary mass, and keeping the light going. With enuff weight plates between the 2 masses, you could greatly extend your initial kinetic contribution, although each travel of the masses would get progressively shortened (depending on plate thicknesses). :dunno: Too much tinkering would be required, as obviously you'd have to eventually reset the weight plates &amp; everything. . .but you could keep the light a burnin' for a while

- it is a cool idea B)


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## FusionWhite (Mar 1, 2008)

The problem with the system of pulling a slightly smaller mass up is that the energy used to pull the other mass up takes energy away which could be converted into light.


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## Dleg (Mar 2, 2008)

Exactly. Conservation of energy dictates the limits to this scenario.


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## TouchDown (Mar 6, 2008)

What ever happened to a candle? If it only provides 40W of light and will probably cost a considerable amount, and takes up space 4' tall... why not just light a candle?


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## C-Dog (Mar 6, 2008)

TouchDown said:


> What ever happened to a candle? If it only provides 40W of light and will probably cost a considerable amount, and takes up space 4' tall... why not just light a candle?


Uhm, safety, for one, indoor air quality for another - sheesh :2cents:


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## ODB_PE (Mar 6, 2008)

error_matrix said:


> :huh: Just spitballin' here - what if the mass, as it descends, pulls a slightly lesser mass up. When said masses reach their terminal descents / ascents, the upper mass would 'dock' with a weight plate, making it the heavier mass, thus pulling back up the primary mass, and keeping the light going. With enuff weight plates between the 2 masses, you could greatly extend your initial kinetic contribution, although each travel of the masses would get progressively shortened (depending on plate thicknesses). :dunno: Too much tinkering would be required, as obviously you'd have to eventually reset the weight plates &amp; everything. . .but you could keep the light a burnin' for a while
> 
> - it is a cool idea B)


On this board we obey the laws of thermodynamics!


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## Dleg (Mar 6, 2008)

C-Dog said:


> Uhm, safety, for one, indoor air quality for another - sheesh :2cents:


Not to mention global warming. HOnestly, think about it: not only does a candle add to the greenhouse gas burden on our planet, but it also directly warms the atmosphere.


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## FusionWhite (Mar 12, 2008)

ODB_PE said:


> On this board we obey the laws of thermodynamics!


Best Simpsons reference of the day.


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## JPGOLF (May 21, 2008)

What about having a motor re-lift the weight? I know it then is not 100% non-electric, but it would use roughly half the power a 40W incandescent would. (bear in mind I spelled ROUGHLY before you start with the power factors, friction losses, etc!)

BTW, I guess since we are all engineers here, I better think twice about what I say! LOL

And yes, it would create emissions, but, it would already be more efficient than an incandescent, CFL or LED (it uses half the power of the LED), keeps it connected to a plug (good for me since I design MEP Bldg. systems). Now about that 4' tube... I guess it won't work!

JPR


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## FusionWhite (Jun 4, 2008)

JPGOLF said:


> What about having a motor re-lift the weight? I know it then is not 100% non-electric, but it would use roughly half the power a 40W incandescent would. (bear in mind I spelled ROUGHLY before you start with the power factors, friction losses, etc!)
> BTW, I guess since we are all engineers here, I better think twice about what I say! LOL
> 
> And yes, it would create emissions, but, it would already be more efficient than an incandescent, CFL or LED (it uses half the power of the LED), keeps it connected to a plug (good for me since I design MEP Bldg. systems). Now about that 4' tube... I guess it won't work!
> ...



Why not just have the motor power the light? Using the gravity light and attaching the motor to is just an extra step not needed.


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## Sschell (Jun 4, 2008)

^LOL!!!

F'n awesome! FW, well done. You should get a patent on that quick before the word gets out!


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