Gravity Light - Alternative form of lighting to replace Kerosene
indiegogo.com
indiegogo.com
http://www.wolframalpha.com/input/?i=20+kilogram%E2%80%90for...
So probably a hoax.
(Wolfram fun fact: thats roughly the energy of the weight of a typical snowflake in oil (~4mg))
It is very easy to read by, easily lights up the whole room in a decent warm glow.
The lamps that people use in these countries are very different from that, being made with makeshift wicks and founts and generally no chimneys. Even so, the light they put off is much better than your average candle.
(http://www.who.int/mediacentre/factsheets/fs292/en/)
> Around 3 billion people still cook and heat their homes using solid fuels in open fires and leaky stoves. About 2.7 billion burn biomass (wood, animal dung, crop waste) and a further 0.4 billion use coal. Most are poor, and live in developing countries.
> Nearly half of deaths among children under five years old from acute lower respiratory infections (ALRI) are due to particulate matter inhaled from indoor air pollution from household solid fuels (WHO, 2009).
etc etc
This isn't to say that the device is any good.
(http://www.who.int/bulletin/volumes/87/9/08-057505/en/)
> Paraffin, also known as kerosene, is among the most frequently used fuels for cooking, lighting and heating among people living in low-income communities lacking electricity in low- and middle-income countries.
> The homes themselves were modest. Almost none had running water and most were constructed of some combination of tin and wood. They averaged 2.0 rooms and 1.4 beds. Although more than 80% of participants had electricity in their home – often through illegal tapping of community electricity sources – they also reported paraffin as their primary fuel for cooking (36.6%), lighting (27.4%) and heating (95.6%). Most (92.8%) participants reported daily paraffin use, and all but one reported at least occasional paraffin use.
Kerosene is still used by very many people for lighting, (even among people who have some access to electricity). The use of kerosene for lighting causes harm.
I'd like to read any sources that you have.
Do you have any sources?
They do if you're comparing it to a kerosene lamp; kerosene has certainly not been "replaced" in parts of the world that don't have easy access to batteries or electricity in general. See the numbers elsewhere in the thread. And it apparently does use an LED light.
A better way to go would be to validate the concept and find a way to produce the lamp and as much parts of it in the target communities, helping them to become self sustainable. The current idea just replaces local economy with earnings for a {american, european, chinese} manufacturer, effectively funneling funds away from the people that you want to help. So the goal is laudable, but I can't support the approach they're taking.
[1] other examples include food help which drives the local farmers out of business or donating clothes. Clothes often get sold for cheaper prices than the locally produced ones. Both may be useful in very specific circumstances, but are harmful in large scale.
For example I live in Europe, and when I get an iPhone... the money goes to the US, but this is not a problem as its technology and its an extra in my life.
But see when you have to buy basic things for living, like food, fuel etc... from non local companies its a problem.
Especially the poorness of Africa is deeper subject and i don't think that tools like that are the cause of it.
This thing can be applied my many more places that lacks electricity and its rather good than bad to have it.
False, and the authors should be ashamed of themselves for posting this lie in a page meant to attract investors:
http://naldc.nal.usda.gov/download/38761/PDF
Also, a wound-mainspring arrangement would be much more effective as a low-cost, practical third-world product. It would be lighter, less costly to produce, and would require much less space. This gravity angle looks like a gimmick, possibly to avoid infringing someone's patent.
That said, now that we've discovered something inaccurate, as long as that information gets back to them, what matters is what they do with the new information. If, after having been informed of what's correct, they continue to say what they had been saying, then we have a real problem. Otherwise, I don't think we have enough information to say anything.
Really, my problem with your statement was calling what they did the "next worst thing". I think that's a bit extreme for what was said, given the little we know about the situation.
That's a somewhat different topic, but it's relevant. Not all scientists can be relied on to deliver accurate claims. Case in point:
http://news.sciencemag.org/scienceinsider/2011/10/report-dut...
All Stapel's papers were published in refereed journals. It will be years, possibly decades, before Stapel's many retracted papers are no longer referenced in the scientific work of other psychologists.
My point? Advertising copy must be vetted by knowledge, not appeals to authority. It only took me 15 seconds to find a source that falsified the claim about mosquitoes, and it's not my field. It can't hurt that I knew it was false at the outset.
The problem with claims about mosquitoes and light is that there are a lot of dishonest vendors who lie about this, and a copy writer with insufficient training will almost certainly repeat the lies of others. I think that's what happened in this case.
For me, the other issues -- deceiving the public, public safety, and due diligence -- lead me to use what might not be the best word to describe it, but lacking a more convenient term, I often use "lying" in a case like this, where the future of the company may well hinge on the initial impression this page creates.
You're comparing ordinary conversation with advertising copy. They aren't comparable. Advertising copy must meet a higher standard -- misrepresentations are sometimes severely punished, and such statements always hurt the company's reputation.
A different standard is at work, and it should be.
I always call advertising-copy misstatements "lies", just because the level of responsibility is higher and the copy writer has no excuse for endangering the company's future. As it happens, the courts agree.
Given that the main idea behind the product is to produce light without any standard energy sources, and not "a new bug repelling lamp!", I would give them the benefit of doubt. Also, the people behind the lamp are regular designers, not a big company which had all the time and energy to verify everything in the article.
Note: I respect your catch. I'm not promoting such misstatements in promotion videos, but the word "lie" is farfetched. Too harsh. Especially with all the other bashing going on here.
[1] http://www.energycircle.com/blog/2009/06/16/newsflash-leds-d...
[2] http://www.energycircle.com/blog/2011/08/17/correction-led-l...
Perhaps. I just get tired of seeing so many casual "misstatements of fact" in advertising copy that can mislead the public and/or cause injury (the latter in the case of tanning beds and other technologies where public health is at risk).
But I agree it's farfetched. It sprang from annoyance and the lack of a better single word.
Do you shame your kids by calling them liars every time the get something wrong on their homework? Do schools kick you out for violating the code of conduct (which usually includes some language about honesty with faculty and administration) every time you get marks off on a test because of factual incorrectness?
Are people who write code with bugs just dirty liars, because the documentation says it will do this, but a bug means that in some cases it fails?
In fact - I wasn't making any comments on the gravity light thing at all. I was simply questioning a poster's odd use of the word lying. I haven't a clue how you are able to turn that bit of semantics discussion into a defense of the product, but I respectfully suggest you turn down your paranoia - you are seeing a scam where there wasn't even a request for money/favor/work.
In ordinary conversation, yes, of course. But not in advertising copy. As to the latter, one cannot claim ignorance.
Try your position in a court of law after someone holds you responsible for an "innocent misstatement of fact" in advertising copy that leads to sales based on a false premise, and/or that causes injury.
Interestingly, about the difference between false statements and lying, this played a part in a scandal at West Point a few years ago, in which some students didn't realize the point you make about ordinary conversation -- lying must be intentional falsehood, with knowledge that the statement is false.
Nevertheless, someone who writes advertising copy can't claim this protection.
> Are people who write code with bugs just dirty liars ...
That's not the same at all. A programming bug isn't an intentional statement, whether true or false. A closer comparison would be someone speaking a word in a language he doesn't actually understand, and not realizing he's used the wrong word.
"You lied, so you should be convicted" isn't true, either. If it were illegal, why do people have to take an oath in court?
Lying may be morally or ethically bad, but in itself, the law is fine with it.
A number of reasons:
* So they can't claim ignorance of the law.
* Because lying in court is such a commonplace that the court system decided a timely reminder would be wise.
* Finally, some statements that are lies can't be prosecuted, for example, anything not material to the issues being discussed. On that basis, the oath stands as a clarification of what is legal and illegal in that specific context.
In spite of the above, lying under oath is very common. It's a rule of thumb that judges will rule against liars rather than try to prosecute them.
> Lying may be morally or ethically bad, but in itself, the law is fine with it.
Yes -- except (two examples) under oath or while filing a police report.
Yes. Dirty, dirty liars.
That seems to be too lenient. If I honestly believe in God's healing powers or homeopathy, am I off the hook for failing to bring my child to the ER when he has a serious illness?
I don't remember all the economics, but the cost of kerosene for x months would pay for the entire setup. Also, the light was an order of magnitude brighter than a kerosene lamp. But the interesting part (again, there's nothing highly technical here) was the business model.
It had a social/micro-finance bent in that he would source investors, who'd invest in shipping containers of these systems, which they'd sell on consignment to local entrepreneurs in poor areas. Those entrepreneurs would pay a fixed interest rate, so the investment was for-profit, and the local entrepreneur would profit from the rest. I remember him talking about building a Kiva-like interface where you could track your investment, right down to the shipping container, village and entrepreneur.
The best thing about this guy moving in was that my co-founder (of Flightfox) was just preparing for an expedition across the Gobi desert and needed solar power for her Macbook so she could blog about the expedition from the desert. All went well and she (Lauren) spent 52 days, trekking 1,000 miles, with full power and ability to blog over satellite the entire time. All using solar panels small enough to fit in a backpack.
That said, love the concept of the gravity light. For anyone who's spent a lot of time off grid, even dim light makes all the difference.
Edit: this system cost about $20.
Their claim is a 20 pound weight raised 6 feet (or so) in the air will generate light for 30 minutes:
20 lbf * 6 ft / 30 min = ~90 mW
For reference, the LED indicators on your keyboard use about 15 mW each. So that's about two keyboards worth of light.
However maybe I'm being stingy -- because of persistence of vision (a characteristic of the human eye), you can run LEDs (or any light) on a low duty cycle and still produce the same apparent brightness. So if we say they run it at a 10% duty cycle (I'm not sure how accurate this estimate is), they might be able to get closer to 1 W of LED light, which is enough for reading.
Quick back of the envelope calculation, using what few numbers are given in the article.
Ballast: m = 10 kg (1)
Height: h = 3 m (2)
Energy stored: E = mgh = 300 J
Time: 30 min = t = 1800 s (3)
Wattage available: P = E / t = 0.17 W (4)
Notes:
(1) Article says you can hang anything weighing about 20 lbs.
(2) No numbers given in the article, but the pictures make it look like ceiling height (8 to 10 ft., I took the larger)
(3) Article says light for half an hour.
(4) With current LEDs this is the equivalent of about a 2 W incandescent bulb, i.e., pretty dim. The light in the pictures in the article looks like the equivalent of about a 40 W incandescent bulb, so the numbers come up short by a factor of about 20. That would indeed be "super-efficient" for an LED; I'm not aware of any even on the drawing boards that are that efficient.
[Edit: The numbers actually are not too low compared to kerosene lamps, which are what this light is supposed to replace. See exchange downthread with xd.]
Human eyes can adjust very well to low light levels.
The GravityLight article does say that it's meant to replace kerosene lamps, which according to Wikipedia range from 20 to 100 lumens:
http://en.wikipedia.org/wiki/Kerosene_lamp
This is about the equivalent of a 1.6 W to 8 W incandescent bulb, so you're right, I was too quick to dismiss the numbers as being too low. They're certainly low compared to what first world citizens are used to, but they are roughly equivalent to what the target users are used to.
Kickstarter is overflowing with game projects raking in the millions collectively with unverifiable claims altogether, like "awesome multiplayer experience". But this stuff? "It's a hoax, they're trying to rip the public off for 55k!" You simply cannot make this shit up.
Energy stored E = mgh (300 J)
Energy stored E = 10 (kg) (9.8 m/sec) 3 (meters)
2940 J
AND I have to correct mine too since I used 180 for time (30 * 6 rather than 30 * 60)
In reality, you will be lucky to get 50% back, and that's with a very good generator.
If you have a 50% efficient generator, just double the size of the ballast; 20kg is still reasonable. Or double the height, though that would be somewhat harder; you would need some kind of pulley arrangement. Or some combination of the two.
Also, I think low voltage DC generators can do considerably better than 50%; the numbers for this kind of application can be quite different than those for the kind of large scale AC generators we're used to.
However, in commercial power generation, the mechanical energy usually comes from some sort of heat engine, the heat for which is provided by fossil fuel combustion or nuclear fission. There is a big haircut in that step. Heat engines are generally only 35 to 60 percent efficient.
Hydro power does much better, but it doesn't use a heat engine; it's just a much larger scale example of converting gravitational potential energy into electricity.
I think the reason this contraption is valuable is that LEDs don't need much power to produce enough light to please someone used to kerosene lamps.
> I think the reason this contraption is valuable is that LEDs don't need much power to produce enough light
Actually, that contraption cannot produce enough light, unless you have a crazy weight, a lot of elevation, and a magical efficient system that converts energy to electricity, and then transforms it to whatever voltage/amperage appropriate for you LED lights.
As far as voltage/amperage is concerned, I would expect the generator to be low voltage DC, matched to some voltage in the range the LED light could support. AFAIK LED lights are fairly tolerant of a range of low DC voltages, so I don't see this as a major issue.
I'm guessing that's pretty reversible - if you spun that motor backwards with the right speed and torque and loaded the output up in just the right fashion, I think you'd get 94% of the energy you put in out as electricity.
The problem I see is that a slowly falling weight is unlikely to provide "the right speed and torque" without some sort of lossy gearbox in between - there's the physical equivalent of an impedance mismatch there. If I had to imagine a motor/generator that'd be likely to work on a direct-drive to a falling weight it'd probably be several feet in diameter. (For model plane motors, the diameter of the motor is a significant factor in the kV constant and the rpm at max efficiency. Small diameter motor spin fast, large diameter motors spin slow.)
First we'll assume that the weight changes altitude by 2 meters, next we'll assume the "weight" is 5 kG (about 10 lbs) it could be more than that if you used denser material but it looks like they are expecting you to fill a sandbag to weight it dry sand is about 1600 kg/m^3 [1] so a sandbag that was 15cm/side would be about .0033 m^3 or 5.3 kg.
The force exerted by that sandbag, 2 meters up is 5 * 2 * 9.8 or 98 Newton-Meters. Now the campaign says it runs the light for 30 minutes so to find the power in watts we take 98 Newton-Meters divide by 1800 seconds (bag goes from 2m to 0m in 30 minutes) and get .0544 watts per second. Assuming the generator is 50% efficient (that is a really good generator) that is about .025 Watts to run your LED. So can you get decent light from an LED with 25 mWatts? At a forward voltage drop of 4V (White LED) that is 6.2 mA of current. (updated to be a decimal order of magnitude smaller)
Given that current LEDs are seeing something like 50 lumens/watt you might see 2 - 5 lumens from such a light. Not nearly as bright as I originally estimated.
EDIT: The time was wrong 1800 not 180
Hang it in the shed or make it into a great porch light, you can clip on a hanging basket or anything weighing about 20lbs.
So that's ~2x your estimate, which doesn't seem impossible.
I do wonder what they're suggesting using for the ballast though, that avoids excessive bulk. Another consideration is going to be finding a suitable mounting point in a typical shack/slum type dwelling.
Good idea, but the physics doesn't work yet. A heavier weight might fix the problem, though. (I use a 5W LED lamp in my apartment that I keep on all the time. It's almost enough for reading and it's certainly enough for walking around at night.)
And/or more height. The numbers are comparable to the low end of kerosene lamps as given.
This thing talks about a 1:600 duty cycle (3 seconds of charging for 1800 seconds of lighting), so, at the very best, it could use a 1.5W LED. Looking a a more realistic 100W human power output (Tour de France riders do 6W/kg or so sustained), it's gets down to .1W or so.
A heavier weight, more height, or more frequent charging all will increase the amount of light produced, but it also means less time to enjoy it.
In the end it all boils down to the fact that a kWh is a lot of energy for a human to produce.
If you're only trying to replace kerosene lamps, you don't need much power. A tenth of a watt with an LED gives a light output comparable to a kerosene lamp. See the numbers elsewhere in the thread.
Why does every crackpot "revolutionary" energy gizmo make this same kind of nonsense claim? "Minute" is not a unit of energy, luminous intensity, or any other measure that is actually useful in evaluating the practicality of this.
The reason I know this is crackpottery is that, as others have pointed out, the physics just doesn't add up. Assuming perfect efficiency, you'd be looking at somewhere on the order of 1% of the light output from a standard 40 watt light bulb.
Yes, about a tenth of a watt (see the numbers upthread). However, that gives an LED light output that's comparable to a kerosene lamp. So it could be worth it for the target users.
I think that'd be easy to fix though.
This has me wondering how much energy a larger scale application could store and what its efficiency would be.
Also this is very poor energy density each kg moved 1m results in 9.8 joules or ~2.7e-6 kWh. So one metric ton moving 1km would generate 2.7 kWh.
Hell, they should combine this thing with clock: a clock with weights that is also a lamp when needed.