For New Lamps, An Unlikely Energy Source: Gravity

Great simple ideas get buried. This is a great idea. I wish it much success.

The same concept could be made in a newly built home with a water tower to store energy with raised water and retrieved when the water flows downward.

Power could be saved via solar and wind and used later when needed.

This story and the headline are misleading. Gravity is not the energy source, the hand that lifts up the weight every 30 minutes is. Gravity is only the means by which the stored potential energy of the weight (the potential energy gained by raising the weight) is converted into kinetic energy so that it in turn can turn the dynamo. I would expect a magazine named "Popular Science" not to overlook something like this.

I got excited when I read this headline, but the story turned out to be a waste of time. Yay, the lamp uses dynamo technology that was invented in 1831 with a weight on one end instead of a crank. Shut down the power plants, our energy problems are solved. Gimme a break.

I like this device, it would be great for camping, you could find some rocks on the ground and bag them up for use as the weight. Dukane24, although a downer, is correct. The device stores the energy it takes to lift the weight, and then uses that energy for 30 minutes to produce light.

LEDs make this much more practical than incandescent lights would ever have been. However it still probably produces a very small amount of light, and to use this method to store energy for something bigger, like a refrigerator, would not be practical. You would need a whole lot of great big giant weights.

@dukane24

If you're going to be such a pedant about it, the energy source is actually the fusion in nearby stars that not only provided the atoms that make our existence possible, but also the light that fuels the food chain. When the person who uses this light had breakfast, that energy was chemically converted by his body into adenosine triphosphate which, at some time during the day, was used by his muscles to contract and lift the bag. I expected that a reader such as yourself, with such formidable scientific insight, would not have overlooked something like this.

I have never seen a product quite like this. The combination of its design, pricing, marketing strategy and intended use make this product unique and noteworthy... surely undeserving of your public dismissal.

@suggestivesimon,

To your second paragraph. You have seen products like this. They are called coo coo clocks. They incorporate the same principal as these lights.

I do like this implementation. No wasting batteries because you forget to turn it off. No being stuck without backup batteries. As long as you have enough energy to lift the weight, you have light. That's really a great idea.

Heck, you are supposed to leave your computer every half hour or so just to get a break, this would be like a timer.

@ ToomeyND

Indeed, any grandfather clock works on the same principle. But, as I wrote, it's the combination of its design (compactness, no battery, external power connectors), pricing (10$), marketing (indiegogo) and intended use (artificial lighting to increase productivity in developing nations) that makes it unique. I've never seen a cuckoo clock or grandfather clock with (even remotely) the same characteristics.

I have to agree that this is far more fiction than fact. And I really hate that they are (in my opinion) abusing the good intentions of many through trying to raise funds for this by soliciting donations with bad and incomplete information. Projects like this will eventually drive away donors who have been burned too many times by big ideas with no realistic shot at meeting their expectations. And I'm no fan of PopSci for helping them to push something so lacking in practical science.

Doesn't anybody realize how much light comes off a kerosene lamp? They use lamps not for accent lighting, but only when they actually need it to accomplish something. A light that small with so little energy can't provide enough light to accomplish much of anything. So in the end, it is NOT a replacement for them unless they want to lower their lifestyle and feel like they are living in a cave.

Anyone who has had the experience of pedaling an exercise bike attached to a generator and battery in order to power even a single CFL bulb knows exactly what I'm talking about.

In this case the math is not hard to follow for this device. U=mgh so potential energy = 9 kg x 9.8 m/s^2 x 1.5 m for a total of 132.2 Joules. So that's the total they can use for 30 minutes of lighting, even if we are generous enough to give them 100% efficiency. By comparison, a low-illumination (40-watt equivalent cfl bulb) uses 10 watts continuously. Since 1 watt = 1 joule / second, in 30 minutes that means they use 10 (watts)* 30 (minutes) * 60 (seconds) or a total of 18,000 joules. That's 136 times more joules than you can store with this system. Or in other words, 1/136th the light of a 40-watt equivalent cfl bulb.

It's just not practical as a replacement for kerosene lamps. And if they can't use it as a replacement, then all those utopian promises are pretty vain. Even if the villagers do then suddenly have free accent lights for occasional use.

Robot, I would LOVE to build it into a home. And I've done all the math necessary to calculate what it would take to use my local abundance of strong nightly winds with a wind turbine in combination with a gravity-based storage system. But the problem is that gravity is actually EXTREMELY weak, and gravitational potential energy is an extremely space-inefficient way of storing energy. I figured I'd need to basically lift a very massive concrete block (high density) about 30 vertical feet in order to store all the energy I use at my (average-sized) home for 1 day, when accounting for probably efficiency losses. Compressing fluids is much more space efficient, for example.

i'm kinda with marcoreid up there, this seems like a good idea from the vantage point of a first world country like the US, Australia and it's spiders, or the United Kingdom. however after watching a very powerful TED talk where the head engineer from engineer without borders admitted his mistake it got me thinking twice about just tossing money at the problem or fixing the problem for them.

it might be tacitly but the people who live in places that "need" the aid that these kinds of organizations give are there because they choose to be. their problem will not be solved until they decide to make the means to solve it themselves, we can bring fresh water to them using systems that we employ here in the US but the problem that we faced is that no one over there can fix the darn things once it's made.

whereas if they made a system that suited their needs, whatever it be, then it would be a system that could be repaired by them on the budget that they could produce on their own time. we should help them solve their own problems instead of just doing it for them.

to mars or bust!

@suggestivesimon,

Then you've never lived!!! ;)

@marcoreid,

Take your typical LED flashlight. Turn it on at a picnic table. It doesn't do much. Now put an empty milk gallon in front of that light. Even better if it has water in it. That little light can do a lot.

@ marcoreid

I appreciate a poster that uses math and physics in his post. Super interesting. :-)

I take issue with a few of your assumptions, though. First of all, as stated in the video, the gravity light only gives a "gentle glow" for 30 minutes. Brighter modes are available which require the bag to be lifted more often. From what I gather, this means every 5 minutes. Furthermore, this isn't meant to be as bright as a CFL. It's meant to replace a kerosene lamp (more specifically a wick-style kerosene lamp, which is *apparently* widely used in developing nations).

Now:
- Wiki tells me that light output from kerosene lamp is 20-100 lumens, but this includes pressurized lamps. So let's assume that wick-style lamps output from 20-50 lumens.
- Modern LEDs typically have an efficiency > 50 lumen/watt. I just checked DigiKey and found many cheap (cheap!) Osram/Cree LEDs that output 50 lumens @ 0.5W (approx 100 l/W).
- A dynamo will get anywhere from 40% to 90% efficiency. I don't know which one they sourced, so let's assume 50% efficiency.
- One thing you forgot to consider is that the light being output by the Gravity Light is directional. Unlike a kerosene lamp which shines equally in every direction, the gravity light only illuminates in a semi-sphere. This means that Gravity Light only really has to produce about half the lumens to get the equivalent illumination (candelas) to a kerosene lamp.

Using these updated assumptions:
The descent rate is 1.5m / 5 minutes = 0.5cm/second
Which means you' re generating 9kg * 9.8m/s^2 * 0.005 meters * 50% efficiency = 0.22W
At 100 lumen/watt, that nets you 22 lumens.
Already, we meet the low estimate of light output from a kerosene lamp. If you factor in the directionality of the Gravity Light, you end up producing about the same illumination (candelas) as a wick-style kerosene lamp, which is the intent. I'm sure you could take issue with some of my assumptions, but none of it is "pie-in-the-sky".

Lastly, once you factor in the other aspects of the problem (kerosene cost can account for 10-20% of household income, the environmental and health consequences with using kerosene, the fact that the Gravity Light can *maybe* be used to charge electronic devices, etc...) this solution offers many advantages. And at the end of the day, if this thing can only light a small desk, at no cost to the user, then it changes the game in terms of a society's capacity to get schooling.

I wish they would do the same thing and dump zillions of pounds of mountains into the deep ocean trenches--which are 7 miles deep--then power the world from the energy generated from the potential. Remember work - force x distance. If you drop a 100 lb weight 7 miles that's about 100lb x 36,960 ft or over 3-1/2 million foot pounds of work! You can probably light a darn many 100 watt bulbs with that!

@marcoreid
could you please tell me how you plan to compress fluids. I know its possible but not easy.
I am sure it is a good idea for many places in the turd world. We often see whole shanty townships burnt out, and the fires all too often started with candles or kerosene lamps. A couple of months ago there was major collapse in the electricity supply in India, wealthy people have a generator, but even poor people could afford somethings like that. If it enables a poor kid to do its homework I am all for it.

I look forward to the future, when all our autos are windup like toys, lol.

@dukane24
I'm going to continue the hate fest here on you because you deserve it. Yes the title misspoke, yes it is you lifting the bag, and thank you suggestivesimon for even proving him wrong. Also the idea is not to replace first world electricity needs but to help make 3rd world lighting needs more economical. So go find a cliff and start walking.

@suggestivesimon
So you replace the humble kerosene lamp with a directional LED that gives you 22 lumens and needs to be 'rewinded' every 5 minutes? Go home and spend your evening raising a 9kg weight every 5 minutes at a height of 1.5 meters(gym owners beware!) while looking at your 60W (or equivalent) light bulb that gives at least 700 lumens!
Whoa!.. Great science! If only I was born in a 3rd world country to live such wonderful times..

come on pehash thats why we have kids! Make them do it.

Here's an example of a device like this one.

A dynamo/generator with a knurled wheel that rides against the tire on your bicycle and generates light for your headlight and taillight. Pedal power in this case. I had on on my bike 35 years ago. C'mon folks, this is such a small whup to be getting so excited over and start fighting no?

World Peace ! lol.

@ pehash

I didn't invent this. I don't give a sh*t. But, I will say:
a) Are you that weak that you can't raise 9kg 1.5 meters? Unless you're an anemic dwarf, that's a BS argument.
b) As lanredneck wrote, "the idea is not to replace first world electricity needs but to help make 3rd world lighting needs more economical"... "Help" and "more economical" being the important bits.
c) There are lots of assumptions in my calculation. Use more weight, a more efficient dynamo and a more efficient LED, and those 22 lumens easily get up to 50 lumens. That's the equivalent of a very decent LED headlamp that you buy to go camping, which (if you've ever used one) is perfectly adequate for most anything.
d) Is it that hard (!) for you to see the benefit of such a device? I mean try imagining living in squalor, having to dig through rubbish heaps to sell enough scrap metal (or whatever other sh*tty task) to be able to feed your kids. One day, someone somewhere pays to send you a device that either helps you cut up to 20% of your total expenses, or allows your kid to do his homework inside while you cook outside. What is your problem with this?! It's not supposed to be a perfect invention... it's a 10$ gadget for chrissakes... it's just supposed to help.

@Bobby_R
The problem with that is that you need a bike. With this, you get the same thing as bike/dynamo/light for 10$, and you don't have to pedal continuously.
And we're not fighting :-) I'd gladly have a beer with anyone here. Doesn't mean we can't have different opinions.

yeah but this is an ingenius little device that allows you to set it and walk away from it for 30 min. I know its no ground breaking tech like Fusion. But its just a neat little thing that can make a small difference to some people with not a whole lot.

@suggestivesimon,

I enjoyed reading your post. It's nice to converse with someone who takes the time to write a detailed and calm response.

I may not agree with all your premises, but I think you have quite a few very valid points. My experience is certainly not all-inclusive, and I can only speak to what I've seen of use. I have spent some limited time in places in Ghana and Nigeria that don't have power, so I feel that I do have some experience with how the lamps are used.

For most cases I've seen, directional lighting is not the desired mode. So while directional lighting can help a few out, most uses I've seen are broad lighting. A group sits in a room and uses the light from one lamp to read, or a person lights up a whole room that they use as a workspace.

What it comes down to for me is this: Why this product? I can go out and buy solar charged accent lighting for $3 a lamp. Keep them outside and bring them in and have all the light you need, for $3 instead of $10. I'm sure we could devise one that is better shaped for giving off reading/working light to a room and has an on/off switch for $5, or even better for the $10 that matches this product. Yet, it will be much more portable and easy to move and put where you want than this device. Why reinvent the wheel? Especially if we make it less portable than what they have now?

If we really are trying to bring them a product that is an improvement on the current one (get rid of kerosene, doesn't cost much, portable, better light) then we have a whole lot of ways to do it better than by saying we can just lift a 20 pound bag once a half hour and store enough energy to make the necessary difference.

Many of the families I've met in Africa spend $5-$10 a month on kerosene for their lamp. I'm certain that they would even pay $30 for a good quality solar charging lamp that will truly give them lots of high-quality light. After all, that's a 3-6 month payback on investment for them. And most of them won't have the money up-front for it, so you can set up microlending programs to help them get it sooner rather than later.

And before we get too excited, let's recognize there is a whole industry of people in Africa that are employed by selling and distributing kerosene. We need to be careful that we don't just walk in and destroy that industry's jobs without allowing them to be replaced. That is, if we send in foreigners to provide these for free, then nobody local is selling or distributing them, and overall jobs are lost locally. I'm much more in favor of offering local africans the opportunity to be distributors of a product. They'll order large quantities, sell and distribute, handle warranty and repair issues, have the training and know-how for it, etc. That way we don't end up crushing some people while we're trying to help others. It happens far too often, unfortunately.

@African Rover

Compressing fluids is really easy. I think you're confusing the words fluid and liquid. Gasses are also fluids. So a hydraulic energy storage device that compresses air into tanks to store energy would be a good example.

@marcoreid
I think one of the biggest differences between solar powered lights and this is the batteries. Solar powered lights have batteries that will degrade after a time holding less and less of a charge. This does not.
Also Solar is not always predictable/constant. This is only reliant that you are there to lift the bag up again. The rest of your poitns do make sense though

@ marcoreid

Ditto :-)

You undoubtedly have more experience with this issue than I do. I know that I'm guilty of falling back on stereotypical (and much too sweeping) views of the misery that exists in certain parts of Africa. Having said that, I don't think any of that erases the potential of this invention.

While your experience might indicate that directional lighting isn't suitable, I'd argue that families and society adopted behavior best suited to the lighting available to them (kerosene). Adding another lighting solution, especially in the context of a sponsored program, certainly can't hurt. If the GravityLight can provide supplemental lighting (as opposed to a kerosene replacement), or power for a radio, or power to charge a cell phone, then it's still a net benefit to the user. As I said before, if it allows your kid to do his homework inside while you cook outside, then I think that's great.

And regarding the alternatives you propose, they're all wonderful. But where are they? If they exist, and are being properly manufactured, and marketed, and distributed, then I'd like to think that lighting in developing nations wouldn't be as much of an issue. If it truly is an issue (which it seems to be), then somewhere along the line, there's a flaw (or many flaws) in what is currently available. These Gravity Light guys have not only come to the table with an idea for an alternative solution, but they've showed up with plans that exist, prototypes that work, a marketing plan that's in motion and a clear vision of where they want to go. And it shows. And the market is responding.

It's very sad to see so many intelligent people failing to spot the diference between a little toy-gift and a real lifechanging solution for 3rd world countries.
Think small.. act big? I'm sure it was the other way around. Probably that little coocooclock/dinamo could be sourced in China for less than 1$ a piece. As marcoreid clearly explained, at 100% efficiency it will convert human power into electricity at an 'astonishing' rate of 70 miliWatts. No wonder they're not keen on releasing any figures for their prototype.
As for charging other items, at 10 watt-hours, it would take lot of lifting (140 times!) to charge your average smarthpone. Even the cheapest phone would still require a 3rd of that.
The eternal issue: should we give them food (and cocooclocks) or machinery and knowhow to build farms?

This is a very good idea. Africa is the testing ground for a lot of new products that we here in America are reluctant to purchase. I honestly think that the continent of Africa could be a significant economic powerhouse in the future because they embrace products that don't burden them with environmental cleanup.

In response to the debate about whether gravity is the source of energy...I suppose it might have been more correct to say that gravity is the source of the INTERNAL ENERGY that turns the clock. Yes, the hand that lifts the bag supplies the potential energy, but the INTERNAL energy of the clock manifests itself BECAUSE of gravity. Gravity does work on the bag and that supplies the internal energy.

I must agree with suggestivesimon. The TRUE source of the energy is our sun. Or perhaps the strong force which is released when nuclear fusion occurs. I imagine that quarks and superstrings are somehow tangled up in the whole shebbang. I feel a song coming on...

ShebBANG ShebBANG...Lalalalalala...SheBANG SheBANG....

Ok...I'll leave.

This is BULLSHIT! This has been around for years and its a stupid implementation. The best one I've seen that works on the same concept is the windup led flashlights. There are cheap ones made in China. Jeez. This is a scam. Why did popsci even print this? TIPS for the "inventors". Use the spring design. It is more compact and can be "charged" by kids.

@m4kby
i think you calling this "bullshit" is a little premeptive. The idea i believe is to "set it and forget it" lift the bag once walk away. As with a dynamo crank flashlight you need to keep winding it and winding it. This uses less energy and time.

Instead of putting a weight on it, why not a large main spring and a key to wind it.

Does that sounds odder than using a bag of dirt?

I have a flashlight clock radio that has a crank, uses a dynamo from Radio shack. It cost me a tad over $20.00.

Wouldn't that be better for those poor people, at least if they get tired of squinting in the dimness from their LED light, they can at least listen to music off their hand cranked radio.

Honestly, these guys haven't really invented anything - the use of a dynamo in a device has been done. They only made it a tad harder by requiring the villager to fill a bag with rocks or soil (obviously the poor don't mind if the plastic bag rips and spills its contents over the floor).

I'd rather send money to have a Walmart Hand Crank Clock, Radio LED 'flashlight' for these people.

I give up... I read through all the comments and will make just one little issue that all of you continually ignore..

In most third world countries, the governments have enough money and aid to build power stations, water filtration plants, schools etc - but they don't because firstly that is sadly the nature of 'man', but more importantly, why bother spending all that money when there are so many willing to come up with these 'wonderful' ideas to improve their citizens lives...

If you want a REAL solution to the worlds problems, then you need to understand we would have to lose around 2/3rd of the population, start replanting forests globally for around 200 years, stop fishing the oceans for approx. 50yrs, return to the horse and cart and lose most of our little 'gadgets' that did not exist when we started the Industrial Revolution and managed quite well without..

The truth is that people don't want to face the truth - I am not some eco warrior, tree hugger or liberal, I am just a realist. The reliance on fossil fuels could be resolved tomorrow, but no one has the balls big enough to implement the changes as they would not get elected into Government, Scientists would lose their funding and you would end up with Riots more akin to Civil Wars.

We are a bloated, lazy, selfish race, interested in 'self' only with a view of global nimbyism.

Sad - but true!

I once read that the question of creation is either in it's idea or in it's action. This lighting power device isn't a new idea but it works and may be of some use. The value in this creation rests in the realm of action.
Those on the other side of the fence who enjoy new idea creations, I leave to debate among themselves.
On another tangent related to unlikely energy sources I think deserves another look is a home size version of a nuclear power plant. Something that would provide about 60 watts for lighting and recharging batteries and last 30 years or more. Also should it melt down I can put it out with a gallon or two of water. It's not a new idea. See Popsci Archives. Search: nuclear lighthouse.

@ suggestivesimon

Lifting a 20 lb weight 5 feet every 5 minutes is NOT a trivial amount of effort! And for the equivalent of one kerosene lamp? I'm inclined to agree with those who see this as an impractical device. Good discussion, though.