
Gravity Light - Alternative form of lighting to replace Kerosene - vikramhaer
http://www.indiegogo.com/projects/282006
======
revelation
At perfect efficiency, this seems to give you about 55mW for a hour, if I
asked Wolfram correctly (for 20kg lifted one meter):

[http://www.wolframalpha.com/input/?i=20+kilogram%E2%80%90for...](http://www.wolframalpha.com/input/?i=20+kilogram%E2%80%90force+meters+in+milliwatt+hours)

So probably a hoax.

(Wolfram fun fact: thats roughly the energy of the weight of a typical
snowflake in oil (~4mg))

~~~
mistercow
I don't think they ever said how _bright_ the light is, so it might "work" in
a very technical sense.

~~~
rlpb
Kerosene lamps are not bright. It is hard (but possible) to read by one. I'd
love to see a calculation that takes this into account. How long would this
device set at the brightness of a typical kerosene lamp last?

~~~
jlgreco
Depends on the kerosene lamp. I have a flat-wick lamp that I picked up for
about $10 (at the supermarket as an "emergency lamp") with about the same size
and with a similar chimney as this one:
<http://en.wikipedia.org/wiki/File:SwissKeroseneLamp.jpg>

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.

------
jimrandomh
Kerosene has already been replaced; batteries are cheaper than fuel, and LED
lamps are cheaper than kerosene lamps. The rest of this page looks pretty
scummy; it says "780 million women and children inhale smoke which is
equivalent to smoking 2 packets of cigarettes every day", which blatantly
fails basic sanity-checking, and as others have pointed out the duration and
brightness numbers for this don't add up either. So this is at best a well-
intentioned but stupid waste of money, and at worst a scam.

~~~
DanBC
Do you have any cites? Here's what the World Health Organisation say (Sept
2011):

(<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.

~~~
jimrandomh
Heating and cooking != lighting. LEDs obviously can't replace stoves, but
then, neither can this.

~~~
DanBC
That link mentions use of kerosene for lighting. Do you have any cites for the
number of people using kerosene for lighting?

(<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.

~~~
jimrandomh
That link is a survey of two towns, conducted in 2007. LEDs are a recent
enough invention that 5 years is a very long time ago. And it asked "what is
your primary fuel for lighting?", not "do you use fuel for lighting?"

~~~
DanBC
I agree that my sources might be poor. But they are the best I have.

I'd like to read any sources that you have.

Do you have any sources?

------
Xylakant
I like the idea, but I dislike the "we'll distribute this for free" attitude.
Distributing any kind of stuff for free has major economic impact, especially
in poor countries where you replace or obsolete parts of the economy[1]. It's
very common in the poorer parts of africa (Mozambique, Zimbabwe, ...) that
people make their living of buying fuel at the gas station and reselling it by
the liter for use in cookers and lamps or by collecting and selling wood.

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.

~~~
boksiora
You are right that the money will go out of the local economy, but this is not
excuse for making better tools and technology.

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.

------
lutusp
> LED bulbs do not attract mosquitos like conventional bulbs.

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.

~~~
nostromo
It's great to correct their error, but I wouldn't immediately presume
malicious intent.

~~~
lutusp
I didn't. I simply said they were lying. Lying is now so common that malice
doesn't need to be assumed.

~~~
sophacles
They were wrong, factually incorrect. That is not lying. Lying implies intent
to deceive. Speaking factually incorrect things if you believe them to be true
is honest but incorrect.

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?

~~~
lutusp
> Speaking factually incorrect things if you believe them to be true is honest
> but incorrect.

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.

~~~
Someone
You are moving the goalposts from "lying" to "being accountable". "I did not
lie, so I should walk free" is not, in general, a valid argument in court (but
it can work in defamation suits. See
<http://en.wikipedia.org/wiki/Defamation#Defences>)

"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.

~~~
lutusp
> If it were illegal, why do people have to take an oath in court?

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.

------
todsul
When I was living in India last year, an Australian tech founder who rented a
room in my apartment said we was tackling the kerosene problem too with solar.
His company (Barefoot Power) wasn't highly technical, but rather put together
components for an efficient solar powered light. The solar panel doubled as a
mobile phone charger (phones are ubiquitous in India, even in the slums, so
this was a huge selling point) and was enough to power the light for a full
night.

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.

------
cleverjake
this seems a lot like
[http://www.museumofhoaxes.com/hoax/weblog/comments/gravity_l...](http://www.museumofhoaxes.com/hoax/weblog/comments/gravity_lamp)

~~~
pdonis
There's an interesting comment about super-efficient LED bulbs in that museum
of hoaxes article. However, the numbers look marginal for this GravityLight
even with super-efficient LED bulbs.

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.]

~~~
rorrr
Your math assumes you have a magical 100% efficient generator to convert
potential energy to electrical.

In reality, you will be lucky to get 50% back, and that's with a _very_ good
generator.

~~~
cynwoody
Electric generators can get up to 95% efficiency, meaning electrical output as
a percentage of _mechanical_ energy input. In the current case, the relevant
input is mechanical energy produced by a slowly dropping weight, so there
would be losses from friction. But overall, I'd expect much better than 50% in
the conversion of gravitational potential energy to electrical energy.

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.

~~~
rorrr
Link to a generator with 95% efficiency please.

> _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.

~~~
pdonis
As posts upthread have shown, the light output will be comparable to a
kerosene lamp, which is what these lights are supposed to replace. It doesn't
take a "crazy weight" or "a lot of elevation". And the difference between 50%
efficiency and 100% efficiency is only a factor of two; that's well within the
range of making reasonable adjustments in the weight and/or height.

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.

------
jrockway
Meta comment: I read the article and then did a back-of-the envelope
calculation on how much energy you'd get out of one of these. Then I clicked
through to the comments and saw that three other comments addressed this.

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.)

~~~
pdonis
_A heavier weight might fix the problem, though._

And/or more height. The numbers are comparable to the low end of kerosene
lamps as given.

~~~
Someone
Neither would fix it.
<http://en.wikipedia.org/wiki/Orders_of_magnitude_(power)> gives 909W for
_"peak output power of a healthy human (nonathlete) during a 30-second cycle
sprint at 30.1 degree Celsius."_

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.

~~~
pdonis
If you're trying to produce light equivalent to what we're used to in first
world countries, yes, you're right.

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.

------
mistercow
>It takes only 3 seconds to lift the weight which powers GravityLight,
creating 30 minutes of light on its descent.

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.

~~~
sophacles
Whether or not the device works - this usage of minute is also apparently unit
of radio power or backlight luminosity, if cell phone makers and reviewers are
to be believed. Declaring crack-pot status based on that usage is kind of
over-the-top, unless you're here to argue that cellphones don't exist and are
mere crack-pot theories as well.

~~~
mistercow
If you take careful note of my wording, I said that _every_ crackpot makes
this sort of claim, not that _only_ crackpots make this sort of claim.

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.

~~~
pdonis
See the numbers below. It's about the equivalent of a 2 W incandescent bulb,
or 5% of a 40 W bulb; but more importantly, it's comparable to a kerosene
lamp, which is what it's supposed to replace. So I don't think a "crackpot"
charge is warranted.

~~~
mritun
It is warranted because the physics doesn't work out

~~~
pdonis
Um, did you look at the numbers? The physics _does_ work out, at least to a
rough order of magnitude. That may not be enough to make it a practical
success, but it's enough to make "crackpot" unwarranted.

------
dexter313
Looks like the half an hour duration is only good for powering a LED at a
small power. The light seen in the video at the 55 seconds mark, shows the LED
at full power and the weight drop speed is about 0.7 cm per two seconds
(again, aproximately from the video), thats about 4-5 minutes for a meter of
height.

~~~
pdonis
_Looks like the half an hour duration is only good for powering a LED at a
small power_

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.

------
stcredzero
Abbey Road studios was partly powered by descending weights when the Beatles
were recording there. At the time, it was the best way to implement a constant
speed motor for the price.

------
danso
So what's the motor made out of that it can be guaranteed to last a decent
amount of time before breaking?

~~~
guard-of-terra
Plastic? The motor in my CD drive is made from plastic and it doesn't seem to
break at all.

~~~
lostlogin
Ahh, that's because CDs are broken technology and should never be allowed into
ones house or possession.

------
IanDrake
Cool idea. It looks like light itself needs some work though. The light is
bright, but it doesn't seem to shine in a very efficient or useful way.

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.

~~~
aidenn0
At larger scales, you are typically limited by the efficiency of whatever is
lifting it. A large generator can convert kinetic energy to electric energy
with very high efficiency (over 95%).

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.

------
guard-of-terra
So basically it will work exactly like mechanical clock with weights (and
cuckoo) do.

Hell, they should combine this thing with clock: a clock with weights that is
also a lamp when needed.

------
Groxx
I like the idea, but what kind of sick, twisted mind thinks it's a good idea
to put the video in a player where they've disabled / hidden the controls?

------
boksiora
I hope those guys make it successful

------
rorrr
This is a hoax. Mathematically and physically impossible.

~~~
pdonis
No, it isn't. See the numbers upthread.

~~~
rorrr
I did see the numbers. They don't support your point.

~~~
guard-of-terra
Did you see the video? They tell you how there are various modes of operation.

~~~
rorrr
Did you see Spiderman? This guy can shoot spider web from his hands!

