Duo create GravityLight: Lamp that runs off of gravity (w/ video)

Dec 13, 2012 by Bob Yirka report

(Phys.org)—London based designers Martin Riddiford and Jim Reeves have created what they are calling the GravityLight, an LED lamp that runs off of nothing but gravity. The purpose of the lamp is to provide people in third world countries with an alternative to kerosene lamps which cause burns and lung ailments to millions of people too poor to afford any other source of light.

The lamp is as simple as it is inexpensive. A cable hangs from a gear mechanism holding onto a plastic bag filled with dirt or rocks. The energy created by pulling the bag downwards is enough to power an LED bulb for up to half an hour. Riddiford and Reeves have posted their creation on the fund sourcing site indiegogo and thus far have doubled the $55,000 goal.

The two note on their page that over a billion and a half people in the world today have no access to a reliable electricity source. When it gets dark, their only light source comes through burning wood, peat, or other biomass materials – the most popular by far, is kerosene. They also note that the World Bank has recently estimated that up to three quarters of a billion women and children regularly inhale smoke from kerosene lanterns, which is they say, equivalent to smoking two packs of cigarettes a day – a situation that leads quite naturally to very high lung cancer rates. Also, millions of people are burned each year when kerosene lamps are accidently upended. There's also the problem of carbon dioxide being added to the atmosphere – collectively about 244 million tonnes a year. All in all they paint a very dire picture. To help fix the problem, the two have spent the past four years looking for and building various lighting options and have now settled on their GravityLight.

Their lamp has no batteries and is made in a way the two say will last for a very long time. The weight that drives the lamp is free and collectable virtually anywhere and providing a lamp that doesn't have any recurring costs will allow, the two say, those that have relied on to use the money they have been spending on fuel, for other essentials. The overall goal is an improved quality of life.

The two expect the GravityLight to originally sell for just $10. After ramping up, they expect that cost to drop to just $5.

Explore further: Finalists named in Bloomberg European city contest

More information: www.indiegogo.com/projects/282006

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User comments : 48

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supersubie
4.5 / 5 (11) Dec 13, 2012
Wow what an inovative solution to lighting!!! No running costs, no pollution and runs on a widely available resource! And all for an amazingly cheap price tag! Hopefuly this will benifit millions across the globe!
El_Nose
2.6 / 5 (10) Dec 13, 2012
Please concisder that most of the people in coutries where this would be a great addition don't make the equivalent $5 USD a month.

this would be an expensive luxury they would have to save up for
yoatmon
2.5 / 5 (11) Dec 13, 2012
That's an old hat as a new application. The German cuckoo clocks have been built for centuries with the same principle based on gravity.
danlgarmstrong
4.8 / 5 (12) Dec 13, 2012
Mr Nose: The lamp will be displacing kerosene from the market. Kerosene adds up to much more money in those families budget. My guess is that they will come up with enough to pay for them. And if they are also subsidized by the government and NGOs they could practically be given away. This is indeed an invention that will help many.

danlgarmstrong
4.2 / 5 (6) Dec 13, 2012
yoatmon: I was thinking the application was obvious as well, but what makes it economically possible are cheap LEDs. Possibly cheap but powerful magnets (new tech?) are used to generate the electricity as well.
dav_daddy
3.2 / 5 (9) Dec 13, 2012
Heck I live in the good ole US of A and I'll take 3 right now. I betcha that a few of those things could make a pretty good dent in my electric bill.
danlgarmstrong
4.3 / 5 (11) Dec 13, 2012
natello: Did you even read the article? The inventors believe they can produce the lamp for $5. Perhaps you think the inventors lie. I think that multiple technologies have improved enough to make the lamp feasible.

Also, you should include in your 'calculations' the economic impact of the health consequences of kerosene. from the article:
"they also note that the World Bank has recently estimated that up to three quarters of a billion women and children regularly inhale smoke from kerosene lanterns,... equivalent to smoking two packs of cigarettes a day... millions of people are burned each year when kerosene lamps are upended."

PJS
3 / 5 (4) Dec 13, 2012
i think they could get this even lower than $5. one (or more?) LEDs, a simple driver circuit, a small generator with gearing, and a cheap housing. of course it depends on production volume, but still, i think it would be possible...
Alphonso
1.9 / 5 (9) Dec 13, 2012
So,no more fossil fuels will ever be needed ever again
GSwift7
3.5 / 5 (12) Dec 13, 2012
You can get lanterns at any sporting goods/camping supply store for around $6.00. Here's one that has a built in rechargeable battery, a solar charger and a hand crank. It switches between high and low power (6 or 3 LED bulbs) depending on how much light you need. With a good charge it can run for up to 5 hours.

http://www.campin...rn/53662

With a retail price of $6.00, the wholesale price should be about 60% of that, so figure around $4.00. If you wanted to buy a whole bunch of them, you could probably get an even better deal than that.

The guys above are just trying to do a crowd funding scam. Just goes to show that there's a ton of people out there who are willing to open up their wallet but aren't willing to open up a google search first.
Guy_Underbridge
2.6 / 5 (5) Dec 13, 2012
You'll still need the fossil fuel for production of ....


You thing that kid refines the kerosene in his present lamp?
VendicarD
1 / 5 (4) Dec 13, 2012
Why live on planet Nebulon when a little arithmetic can put you on planet earth?

"I betcha that a few of those things could make a pretty good dent in my electric bill." - day-daddy

Running cost of these devices = 0

Running cost of what they replace? Lets estimate.

It looks like we have around 5 kilograms of soil powering the lamp by dropping around 3 feet. The system is claimed to waste at least half the energy.

So we have a force of around 50 Newtons working over a distance of 1 meter, so around 50 Joules of energy are expended, 25 of which make it to the led, which lights for around 25 * 60 seconds which turns out to be 1/60th of a watt.

LED lamps are not significantly more efficient than CF bulbs but for the sake of argument, lets say twice as efficient. So we need a 1/30th of a watt CF bulb to replace on of those LED lamps.

Now you can't purchase CF bulbs that small, but we can purchase a 9 watt CF bulb which produces around 40 times as much light as three of the CONT.
GSwift7
2 / 5 (4) Dec 13, 2012
However, retail products from camping suppliers isn't really the best option:

Here's a project already under way that ships the parts to the local people and they build the lights themselves. There's only one charging station/solar panel for every 50 lights. They have to supply thier own housing for the light (coffee can, water bottle, etc.). This should keep the cost per light way under $5.

http://tlc.howstu...ting.htm

The best part about that project is that they are actually selling the light kits at a price the people can afford, and using the profits to sustain the operation.
VendicarD
1 / 5 (3) Dec 13, 2012
LED contraptions being sold here. So we will divide our final costs by 40.

A 9 watt CF bulb - presuming it is lit 8 hours a day consumes around .072 watt hours of energy. Over a year it will consume 28.8 kilowatt hours of energy, costing around $3 per year.

So, dividing by 40 you save 7.5 cents per year if you use those three units.
Sonhouse
5 / 5 (2) Dec 13, 2012
Please concisder that most of the people in coutries where this would be a great addition don't make the equivalent $5 USD a month.

this would be an expensive luxury they would have to save up for

But there would be no batteries to buy or need to have electricity in the house. How many watts or milliwatts does this device generate for that half hour?
dav_daddy
3.5 / 5 (8) Dec 13, 2012
Why live on planet Nebulon when a little arithmetic can put you on planet earth?

"I betcha that a few of those things could make a pretty good dent in my electric bill." - day-daddy

Running cost of these devices = 0

Running cost of what they replace? Lets estimate.

It looks like we have around 5 kilograms of soil powering the lamp by dropping around 3 feet. The system is claimed to waste at least half its energy


Spoken like a man who has no kids. A little real world math from my home.

We have 2 children living at home full time. Each child leaves at a minimum 2 lights burning somewhere on the premises each and every day.

A conservative estimate would be my home is unnecessarily illuminated 8 hours a day per bulb with an average consumption of 36 watts per hour.

That would come out to 841 kilowatt hours per year. Figuring energy costs at 24¢ per kwh I'd save $202 per year.

Plus

The satisfaction of watching the little dears shoveling to turn on the light = priceless.
Newbeak
5 / 5 (2) Dec 13, 2012
Wouldn't a simple wind-up mechanism be better? It would likely power the lamp longer,and you could place it on a table.
VendicarD
3 / 5 (4) Dec 13, 2012
Your calculations are wrong. 36 watts * 4 bulbs * 8 hours * 365 days = 420 KwH, not 841, and your expenditure would be $100 per year.

"That would come out to 841 kilowatt hours per year." - DayDaddy

If you purchase 4 CF bulbs for a total cost of $12, you will save
$75 in electricity costs per year, down from $100, and have essentially no change in illumination levels.
VendicarD
3 / 5 (4) Dec 13, 2012
"Wouldn't a simple wind-up mechanism be better?" - Newbeak

No. The force exerted by a spring changes as it is wound or unwound thus without additional circuitry to compensate, the light would change brightness as the spring unwinds.

Secondly, it would be difficult to wind - you would need to exert a force of several kilograms on the winding mechanism.

Keeping it simple, makes it easier to be made durable.
VendicarD
1 / 5 (2) Dec 13, 2012
1/60th of a watt or less - estimated above.

"How many watts or milliwatts does this device generate for that half hour?" - Son
IronhorseA
1 / 5 (2) Dec 13, 2012
Your calculations are wrong. 36 watts * 4 bulbs * 8 hours * 365 days = 420 KwH, not 841, and your expenditure would be $100 per year.

"That would come out to 841 kilowatt hours per year." - DayDaddy

If you purchase 4 CF bulbs for a total cost of $12, you will save
$75 in electricity costs per year, down from $100, and have essentially no change in illumination levels.


Correct on the energy usage, but at 36 watts per bulb he's probably already using CF. So he'd be switching to dimmer CF's to save energy. That leaves the question of which 4 bulbs does he change?
Parsec
5 / 5 (5) Dec 13, 2012
Please concisder that most of the people in coutries where this would be a great addition don't make the equivalent $5 USD a month.

this would be an expensive luxury they would have to save up for

Other innovations of similar cost, like improved cook stoves and bed netting are widely used in even the poorest countries. At $2US-$10US/liter for kerosene, you don't have to run a kerosene lamp very long to pay for this 10 times over.
ormondotvos
5 / 5 (2) Dec 13, 2012
So twice an hour someone gets up and lifts twenty pounds six feet. For that small effort and the price of ONE liter of kerosene, they get clean cool light instead of stinky, expensive, dangerous and unhealthy kerosene light.

A literally brilliant idea, but I wonder if the factory should be in the country of use? Also, can the parts be printed with a 3D printer? And I wonder why they use the fancy tape instead of an easily replaced piece of monofilament line? Could you glue a couple magnets somewhere in the workings of an old alarm clock and do the same?

Still, I'm very much in favor of such things. Bill Gates could buy 100 million of them and not even notice.

VendicarD
1 / 5 (3) Dec 13, 2012
"at 36 watts per bulb he's probably already using CF" = IronHorse

Probably not since 100 watt equivalent CF bulbs use 18 to 20 watts.

He may have his house populated with 200 watt equivalent bubls, but given their immense physical size, that is also very doubtful.

He could also have his house populated with 40 watt incandescent bulbs but you would think that if he did, he would call them 40 watters rather than 36 watters.

Most likely he is just mistaken.

"That leaves the question of which 4 bulbs does he change?"

My bet is that he has already changed them, and simply wants to overestimate the amount he is paying for the wasted energy.

His 24 cent per KwH energy cost estimate is also highly suspect.
ValeriaT
1.4 / 5 (10) Dec 13, 2012
Lamp that runs off of gravity
These lamps are dangerous, when used in wider scale, as they're slowing down the Earth rotation during each run... What we will supposed to do, when the gravity will get finally depleted?
MRBlizzard
2.3 / 5 (3) Dec 13, 2012
Assume that there is no electricity running to the home. Kerosene, photocells into batteries (capacitors wouldn't need replacement), or this invention. You could put the weight up until needed in the middle of the night. It might even make a good burglar alarm, if you use with a string.
TransmissionDump
1 / 5 (1) Dec 14, 2012
I can feel a "How many [insert something] does it take to change a light bulb joke coming on...
powerup1
5 / 5 (1) Dec 14, 2012
Please concisder that most of the people in coutries where this would be a great addition don't make the equivalent $5 USD a month.

this would be an expensive luxury they would have to save up for


Name the place where people make less than $5 a month? I have heard of places where people live on $1 a day, but I never heard of a place where people live on less than $5 a month. Please tell of this place.
VendicarD
3 / 5 (2) Dec 14, 2012
"What we will supposed to do, when the gravity will get finally depleted?" - ValeriaT

Economists tell us that when a resource is depleted people will just switch to alternative sources.

So when gravity is depleted, people will turn to alternatives to gravity to keep themsleves stuck to the earth.

Economists believe that the most cost effective alternative will be crazy glue and or elastic bands.

Some Economists believe that Velcro would work better.

Randite Economists insist that no alternatives are needed and that floating aimlessly in space would be a boon to individual freedom.

_traw_at
5 / 5 (1) Dec 15, 2012
"at 36 watts per bulb he's probably already using CF" = IronHorse

His 24 cent per KwH energy cost estimate is also highly suspect.


Not that much: It depends on where he lives. Electricity costs 28.10 cents/kw in Hawaii, and 19.25 cents/ kw in Connecticut. (2010 figures not including taxes). Those prices could have gone up by now.
Those numbers from this source:
https://www.green...e5_a.xls
And prices in Europe and elsewhere are probably much higher. I think electricity in the UK is about 48 cents/ kw.

The idea of using a weight to power an LED is a good one, sort of like adapting the mechanicals of a grandfather clock to generate electricity for lighting.
This idea is definitely worth supporting instead of nay-saying. I will point out that a lot of the parts for these could be made from reclaimed and recycled plastic.
ValeriaT
1 / 5 (3) Dec 15, 2012
This idea is definitely worth supporting instead of nay-saying
Only if it's really economically effective, which is not so-definitive without thorough economical analysis. Without it you're just providing the occupation for western companies, whereas the African world gets even poorer (as usually).
Q-Star
2.6 / 5 (5) Dec 15, 2012
Only if it's really economically effective, which is not so-definitive without thorough economical analysis.


I agree with that one, it's not rocket surgery or brain science,,,,

If the analysis is not effective than the economy will surely slip into a precessional coherence due the like charges attracting and the unlike charges attracting also due to the virtual realitons colliding at the speed of water waves.
Lurker2358
1 / 5 (4) Dec 15, 2012
Name the place where people make less than $5 a month? I have heard of places where people live on $1 a day, but I never heard of a place where people live on less than $5 a month. Please tell of this place.


I don't believe either claim is true.

There are foreign currency market evaluation scams involved.

For example, a person who allegedly makes only a few hundred dollars a year owns a car. How?!

they are either lying about their income, or they are falsely devaluing their currency in the market, for some reason. Nothing else would make sense (excluding gifts from wealthy relatives overseas in Europe or the U.S. or such).
Lurker2358
1.8 / 5 (5) Dec 15, 2012
So twice an hour someone gets up and lifts twenty pounds six feet. For that small effort and the price of ONE liter of kerosene, they get clean cool light instead of stinky, expensive, dangerous and unhealthy kerosene light.


Gravitational Potential Energy:

Ep = MgH

10kg * 2m *9.879m/s^2 = 197.58 Joules

or we can use position formula to get velocity and multiply by max kinetic energy.

4/9.879 = t^2

t = 0.63631696606626456176697849992884s

v = 9.979m/s^2 * t = 6.286175307768627605695980600797m/s

Ek = (1/2) v^2 = 197.58 Joules

This will run a 15 watt bulb for about 13 or 14 seconds...ideally...

It will run a 1 watt bulb for 3 minutes 17 seconds...ideally.

In order to get any appreciable light from this contraption, they'd need to lift a few tons with a pulley or something.

With normal amounts of mass the light won't be enough to even get you back to your chair.

If they are getting light from this, then something is seriously screwed up with the definition of "Energy"..
Lurker2358
1.8 / 5 (5) Dec 15, 2012
I'd recommend they spend the $5 on Kerosene or 2 bags of sugar which they could burn. It will provide more light during it's lifetime.

Amount of energy in a bag of sugar: 28,602,000 Joules (as food calories).

If you're going as pathetic as 1 watt, the bag of sugar can give you light for 11 months, and even at U.S. rip-off prices, you can get 2.5 bags of sugar for $5...

But if you are going to be lifting on rocks and stuff to power a gravity lamp all the time, well if you ate those same food calories, your body is only 10% efficient, and the gravity light is probably only 20% efficient, making the whole system 2% efficient. Takes food calories to lift those rocks (conservation).

Burning bags of sugar for lighting is 125 times cheaper, and won't break your back in the process...
RealScience
5 / 5 (1) Dec 16, 2012
@Lurker - I applaud your doing the math (although two-place accuracy would be better than all of the superfluous digits). And in the first world, or anywhere that electricity is already available, your math is applicable.

However some third world areas have simpler needs. People used to read by the light of a candle, and it only takes a high-efficiency LED 0.1 W to approximately equal one standard candle. At 0.1W your 200 Joules would run a light for 30 minutes, which matches what the article states. An LED is also easier to focus into a beam, making it better for reading, sewing, sharpening tools, etc. (To be sure, a kerosene lamp produces FAR more light, but that may be much more light than is needed.)

If the price can truly be down to $5, then this might make the difference between a child being able to study after the chores are done or someone being able to earn a few extra dollars a month.
astro_optics
2 / 5 (4) Dec 16, 2012
Crap! That's Muscle power Power based, this article is misleading!
VendicarD
not rated yet Dec 16, 2012
I actually use a 1 watt LED lamp for a porch light. Works well enough to show me where the stairs are and where to put my front door key.

I tried it in a 10x12 room one night and it easily gave enough light through the entire room to navigate the room, although not enough to read.

Mazarin07
not rated yet Dec 17, 2012
Very, very good idea, but the energy isn't given by gravity but by human muscles.
I don't care about how much people from poor countries earn. There are poor people everywhere: in US, in GB, in China, Japan, Vanuatu etc. If they can buy kerozene and not this lamp, then I'm soo much sorry for them.
rockwolf1000
5 / 5 (3) Dec 18, 2012
The economical perpetuum mobile doesn't work yet. You'll still need the fossil fuel for production of LED, semiconductors, plastic and transport and distribution. This amount of fuel can be estimated like the volume of oil of the same price.

And you need fossil fuels to make kerosene lamps, and kerosene, and kerosene containers, and for shipping kerosene. You need to look at the big picture dumbass.
dev2000
not rated yet Dec 19, 2012
interesting idea.. if executed properly it will provide a quick easy way to recharge the batteries by simply lifting the weight
ValeriaT
1 / 5 (3) Dec 19, 2012
You need to look at the big picture.
Kerosene lamp is cheap and easy to improvise without introductory investments. Apparently, the poorer country, the less effective technologies it is using and you cannot break this rule so easily. I'm just explaining, why some things don't work as easy as you may think. If we would really take a look at the big picture, then we would already use the cold fusion routinely.
ValeriaT
2 / 5 (4) Dec 19, 2012
My favorite example of the "humanitary design" is this solar grill. It's built of pile of stainless steel, it uses Fresnel lens and the lithium nitrate salt serves as a heat transfer and storage agent in it. Great, this is how these high-tech gadgets are supposed to be used. This is where these ideas usually end. The gravitational lamp described above may not be such an extreme example, but it's not surprising for me, just the silly American kids, who are separated from reality, do applaud these things.
The Alchemist
1 / 5 (2) Dec 20, 2012
Ever wonder why an single LED in a watch-battery powered flashlight produces about 1/3 of the light of and LED bulb, and much cheaper? Yo! I'd love to see this stuff in the US, around the world, if only we could somehow not buy the greed and hypocrisy.
RealScience
not rated yet Dec 20, 2012
Actually ValeriaT is correct about what happens to MOST First World designs for the Third World, and the sleekness of the gravity light prototype has me worried about their cost target.

But just because most such designs are failures or become first world toys is no reason not to try - the few that succeed (such as the rollable water carrier) make a huge difference to peoples' lives.

@Alchemist - the watch battery powered LED actually produces much less light. The beam is almost as bright because it is FOCUSED into a fairly tight beam rather than being spread out the way light from a plug-in LED bulb usually is.

To paraphrase Machiavelli: "Do not attribute to greed and hypocrisy that which can equally well be explained by the laws of physics."
Voice of Doom
1 / 5 (2) Dec 21, 2012
What if you live in a gravity-free zone?
The Alchemist
1 / 5 (2) Jan 08, 2013
@RealScience-I see your point, but darn it, magine 10 watch-powered battery lights, plugged into a wall. Its not the same, watch-power generates disproportionately more light. I know, I was stupid enough to buy the 50-plus LED light-bulb, you can't read by it (without fatigue).
RealScience
5 / 5 (1) Jan 08, 2013
@Alchemist - LED lights for battery power are typically optimized for energy efficiency because batteries (even rechargables) cost far more per Watt-hour than grid electricity. In contrast LED lights for on-grid applications are typically optimized to reduce the cost of the LEDs.
Even when the same LEDs are used, the grid-connected lights are less efficient because they are driven harder (higher current); this produces more light per LED (reducing LED cost) but less light per Watt (this decrease in efficiency is referred to as 'droop').

We have two of the ~50-LED bulbs that my wife bought years ago. They are actually reasonably bright, but the spectrum is horrible to read by so that is probably what is tiring your eyes. Fortunately modern LED lights have much better color and emit light over a broader spectrum.

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