A $5 Lamp Powered Solely by Gravity

http://enpundit.com/a-5-lamp-powered-solely-by-gravity/

by TannerLD • 14 years ago

253 88 14 years ago

enpundit.com

ColinWright3• 14 years ago

Previously submitted and seriously doubted:

http://news.ycombinator.com/item?id=4889266

In that thread[0] revelation[1] said:

    At perfect efficiency, this seems to give you about
    55mW for a hour, if I asked Wolfram correctly (for
    20kg lifted one meter) - [2] - So probably a hoax.

[0] http://news.ycombinator.com/item?id=4889426

[1] http://news.ycombinator.com/user?id=revelation

[2] http://www.wolframalpha.com/input/?i=20+kilogram%E2%80%90for...

tonyarkles2• 14 years ago

If you read some of the followups and tweak the math a little bit, it works out reasonably well. Instead of 20kg and 1m, 20lb and 2m, which comes out about the same (49.42mWh). If you have to lift it every half hour, that's 100mW for a half hour. That's more than enough power to get a useful amount of light out of an LED.

For example, this LED uses 68mW https://www.sparkfun.com/products/531 and is marketed as "so bright that it hurts to look directly at them"

duskwuff2• 14 years ago

That's assuming a perfectly efficient dynamo and no mechanical losses. (Which are both huge assumptions.)

ars3• 14 years ago

It's hurts to look at it because it's focused into a very narrow beam. Very bright sure - in one tiny spot, and totally useless to illuminate a room.

They even include a photo of the beam pattern - it's almost as focused as a laser.

(You can tell on an LED by looking a the top - round tops are focused, flat ones spread out.)

pdonis6• 14 years ago

Um, please read the entire previous thread before dismissing this as a hoax. As you can see from a number of posts that I and others made there, the light is comparable to a kerosene lamp, which is what it's intended to replace. It is not, of course, comparable to the kind of light we in developed countries are used to, but that's not what it's intended for.

ars3• 14 years ago

Using the numbers above and the typical LED efficiency you get 5 lumen of light per half hour ASSUMING perfect mechanical efficiency.

http://www.wolframalpha.com/input/?i=20+kilogram%E2%80%90for...

A simple wax candle produces 11 lumen. And there is no way you will get anywhere near perfect efficiency.

So at best, this will product maybe 1/3 of the light from a candle.

If you directed that light into a small spot, it could be useful, but of course it's a large device and you can't do that.

If you illuminated a room with it it would be enough to walk around and not crash into things, but not enough to read.

Another comparison: Assuming a 2 meter by 2 meter room (which is tiny), this would produce 1.3 lux (again, assuming perfect efficiency).

Moonlight produces betwen .25 and 1 lux.

So at best, with reasonable efficiency, and assuming a tiny room, this is comparable to moonlight under a full moon.

Can you read in moonlight? Go try.

retube• 14 years ago

well here's the agency behind it... pretty elaborate if it is a hoax: http://www.therefore.co.uk/our-work

ChuckMcM• 14 years ago

I don't think its a hoax (I commented in the previous thread, initially skeptical but we worked out the math)

It may not be as useful as someone might like, which is to say you won't get a lot of light out of it. But unlike the candle example all of the light will be going roughly one direction. Think 'keychain LED flashlight' kind of light.

So in a place that literally has no light, it will be helpful. That last door in the dungeon, your village storage hut 30 miles from the nearest town on moonless nights. If you don't mind running the generator faster you can get brighter light for less time.

I took apart one of these [1]: http://www.amazon.com/FR160B-Microlink-Self-Powered-Weather-... which is Grundig crank powered radio/siren/flashlight. Its pretty bright, and you can power the LED off the internal generator directly. In fact if you were handy with some shop tools you could probably build your own version of this light with just this radio thing and mechanical connection between the crank and the weight. (You would leave the flashlight set to 'on') You wouldn't get 30 minutes of light, more like 2 minutes. But conceptually the idea is the same.

I like the design ethos of the 'clock' style energy source (I've got a grandfather clock that you wind by pulling up the weights on it).

I expect in a nominally lit urban environment it will provide little benefit. But that doesn't mean I believe it will be useless in all environments.

[1] I've now received 3 of these for 'free' (one as a conference giveaway, one came in a kit of earthquake supplies, and one was added into a garage sale purchase of other stuff. They kinda suck, in that they break pretty easily and once they do they don't work (internal wiring breaks). So finding a broken one shouldn't be all that hard if you're looking to experiment.

degobah• 14 years ago

Technically powered by the effort of lifting it.

mmanfrin2• 14 years ago

Technically powered by the food eaten to lift it.

Technically powered by the sun.

Technically shut up with useless pedanticism.

Jach• 14 years ago

It's not very useless. The title suggests a perpetual motion machine, so I was wondering what that was doing on HN. Knowing you have to lift it first (from the article or from the comments) is important to know and lets one think this isn't necessarily made up.

icambron• 14 years ago

I don't think that's useless pedanticism at all. If you didn't know anything about physics, you're likely to hear "powered by gravity" and think "great, gravity is ubiquitous and free, so this is totally free energy", whereas actually these poor people will have to eat more in order to light their homes. So it's important to communicate what you actually have to do to power this light.

On the other hand, your "if you're reductive at all, you have to be 100% reductive all the time or shut up" argument is completely unhelpful.

dsl• 14 years ago

Not to nitpick, bit it's not powered by gravity, it is powered by people going over every 30 minutes and lifting a weight back up to its top position.

EDIT: Apparently people don't understand that using gravity to generate energy is a thing, and the title "Powered Solely" suggested someone found a way to do that.

tarice• 14 years ago

People couldn't lift the weight without consuming energy from food. Doesn't mean that it's powered by food.

The machine converts gravitational potential energy to electromagnetic radiation. People generate the gravitational potential energy by lifting the weight using kinetic energy, which was likewise created by converting chemical energy.

It's easier just to say "Gravity" because, without gravity, it wouldn't work with its inanimate weight.

emiliobumachar• 14 years ago

I suppose it all ultimately comes from solar energy, which, in turn, comes from nuclear fusion.

tjic2• 14 years ago

> People couldn't lift the weight without consuming energy from food. Doesn't mean that it's powered by food.

Actually, it does, and that's the perfect way to analyze this. Food is good for keeping humans alive, but it's a pretty foolish fuel to burn in a human engine to accomplish things. It's perishable, it's eaten by rodents, it's hard to transport, and more. I chuckle darkly when someone tells me that something is "green" because it's human powered. Growing food isn't free - it uses conventional energy sources to harvest, transport, etc., and it's a ton less efficient than just burning that fuel directly.

libria2• 14 years ago

When I think "powered solely by gravity" I think of something like a hydro electric plant which can generate more energy than is required to operate it.

At any rate, the phrase was written by Enpundit, not GravityLight. Their indiegogo page is less dramatic and more scientific about what powers their lamp:

http://www.indiegogo.com/projects/282006

pyre• 14 years ago

Gravity is the storage mechanism. When someone says something is battery-powered, do you start an argument about how that technically isn't correct?

njharman2• 14 years ago

Probably yes. Annoying pendants are predictably annoying.

nuclear_eclipse• 14 years ago

Gravity isn't the storage mechanism; the ballast bag is. Gravity is the mechanism used to unleash the stored energy, the same way that the electro-chemical voltage difference between the two components of the battery is the mechanism that unleashes the stored energy in the battery. If anything, it's a ballast-bag-powered light.

biot• 14 years ago

I was a bit disappointed by the title. I was hoping for something akin to a sterling engine, which is powered solely by a heat differential. As long as the heat differential is present and barring any mechanical issues, the sterling engine will operate continuously without intervention.

nwh• 14 years ago

They're incredibly efficient. There's one on my wireless router that happily spins away all day.

ColinWright3• 14 years ago

If you bury a heatsink, and then have an air-flow heatsink, it's plausible that you could power a Stirling Engine with this kind of power output.

You wouldn't do it for $5 though. Efficient Stirling Engines with a reasonable amount of torque actually require significant engineering, and that comes at a cost. However, they wouldn't require significant maintenance, they would provide power all the time that could be stored (again, at a cost), and might be able to trickle power an entire village.

SoftwareMaven• 14 years ago

I'm pretty confident that most comments that start with "not to nitpick" would be better sent to /dev/null. Nitpicking is usually a sign that deeper, more interesting arguments aren't available, but negativity must reign supreme!

Shouldn't it be said that it is powered by vacuum energy, since that is what kicked of the Big Bang? (And, before anybody tells me I'm wrong, let me say, "I'm wrong!" Instead of telling me I'm wrong, educate me. I love learning about this stuff, and I know my knowledge is weak.)

Lagged2Death• 14 years ago

Some people get excited by F1 racing, the Bugatti Veyron, or stuff like the latest iPhone, telling you they are technology enthusiasts or engineering fans.

But if you ask me, it's always at the low end of things - like this project - where the really inventive, exciting engineering happening.

Sure, something like an F1 car is impressive after a fashion, but considering the price, yeah, well, it better knock my damn socks off or it just looks stupid. Unlimited budgets do not make for impressive engineering, really.

Making something that is truly, spectacularly useful like this for $5 ot $10? That is genuinely impressive.

zem2• 14 years ago

indeed! having lived in india, i get particularly excited by projects that could provide grid-free lighting and clean water to rural areas.

also, a quick plug for my blog [http://aleverlongenough.wordpress.com/] rounding up projects like this - it was unfortunately short-lived because life got busy, but i hope to restart it in 2013.

tjic2• 14 years ago

> i get particularly excited by projects that could provide grid-free lighting and clean water to rural areas.

The best way to provide lighting and clean water is via the grid: power lines and water pipes.

daeken• 14 years ago

> it's always at the low end of things - like this project - where the really inventive, exciting engineering happening.

That's why I got into the demoscene. While I'll drool over the crazy new demos pushing the latest GPUs to the limits, it's always more impressive to me when people take extremely limited systems and file sizes and do incredible things with them.

ZeroGravitas• 14 years ago

"To define it rudely but not inaptly, engineering is the art of doing that well with one dollar which any bungler can do with two after a fashion." -- Arthur M. Wellington

CamperBob2• 14 years ago

My favorite way of expressing the same thing: "Anyone can design a bridge that will stand up. It takes an engineer to design a bridge that will barely stand up."

Not sure where this came from -- Douglas Adams, maybe?

sliverstorm• 14 years ago

You're just paying attention to different constraints. Engineering with zero constraints is pointless- but an F1 car operates within all kinds of constraints that are not money. You just aren't familiar with them.

ErikHuisman• 14 years ago

You might think it is "truly spectacular" because it is unique to you. But you have to question yourself if it is really THAT effective. One could buy a hand cranked powered led light for cheaper. Sure, it'll take more time to power it. (Few seconds vs a minute). If i could afford neither i would go for the second option.

obilgic• 14 years ago

First thing I thought when I saw the title was: Linux, apache, mysql, php...

bmelton2• 14 years ago

I'm not sure why you were downvoted, as I bypassed the article probably at least a couple times before realizing that it didn't say "Lamp Server" and just said "Lamp".

rijoja• 14 years ago

"A $5 LAMP Server Powered Solely by Gravity", if I read that I would have clicked instantly.

NathanKP2• 14 years ago

Maybe I'm stupid for asking but what is the advantage of this over a spring powered wound clock? My wristwatch can tick for two days on a wind, and while it isn't as cheap as this gravity powered wound clock I'm sure it could be made cheaper. There is nothing special about this invention; purely mechanical "gravity powered" clocks have existed for centuries in the form of old grandfather clocks etc.

marquis2• 14 years ago

Yes, I was thinking the same thing. You can buy now on Amazon a hand-crank LED light for $12, so surely these can be made far more efficient and cheaper with $200,000.

FrojoS• 14 years ago

But those require a battery, which will only survive so many (hundred?) recharges, no?

morsch2• 14 years ago

The advantage of this lamp over a spring powered wound clock would be that it emits light. The disadvantage is that it's comparatively poor at keeping the time.

NathanKP2• 14 years ago

True, but my question is if a clock winding mechanism can keep going for days without need of winding could a clock winding style mechanism be more efficient than a gravity weight powered one.

jstsch• 14 years ago

Similar in concept to the Waka Waka light, except that's powered by a solar panel (and some quite nifty electronics):

http://www.wakawakalight.com/

joeyh• 14 years ago

I use kerosene lights by choice in the winter in weeks like this one when there is no sunshine. So, here's my firstish world problems take on it. May not apply to people for whom a gallon of kerosine is a significant fraction of their monthly income.

I have a hard time seeing myself using something like this, except as task lighting. I'd be fine to have to lift a weight if I was only going to be using the kitchen for 30 minutes (it could even serve as a useful timer), or similar. But getting up every 30 minutes rules out using it anywhere I need longer duration light for eg, reading.

Also, anywhere I could use this, I could use any of the many inexpensive crank LED lamps available everywhere, which run for similar amounts of time.

The pity is that, with the right design, this could support a longer cord for a further lift distance, so it'd run an hour. Or multiple weights used in sequence or parallel so it can be primed for even longer (iirc that's how my grandparent's cuckoo clock worked). From what I can see, it's not designed to be very hackable, and something like this needs hackability.

The LED light is the other problem with it; I'd much rather have a well ventilated kerosine light than blue tinged LED for almost any task. (I'm curious to see studies about kerosine health risks however.) Since this light cannot be moved, it has to illuminate the whole area, and its light doesn't seem up to it, so I'd be doubtful about eg, reading by it either.

geophile• 14 years ago

This idea just hit me, and it's so powerful I'm still reeling. What if someone built a battery-powered weight lifter that would go off every 1/2 hour? You wouldn't have to keep getting up to do it yourself!

Not sure if I should patent this, or just donate it to the greater good of mankind.

K2h• 14 years ago

are you proposing propetual motion? if you have the energy to lift the mass, you have the energy to power the light directly and bypass the losses of setting up the dravity weight again.

marquis2• 14 years ago

>a gallon of kerosine is a significant fraction of their monthly income

It's not just that, it's also extremely polluting (both for the immediate and greater environments) and dangerous. The kerosene isn't the most expensive part, it's buying a good quality lamp that won't tip over or leak toxic gases.

http://flexiwaysolar.com/kerosene-lamps-the-problem/fire-ris...

eliben• 14 years ago

As always, the devil is in the details here. Does this lamp produce enough light for a family to be motivated to actually lift it every N minutes (e.g. does it produce enough light to read comfortably, or to cook a meal)? Is it durable enough to survive in essentially outdoors conditions in terms of heat and humidity? If the answers to these questions are positive, it's certainly a great invention. If not, back to the drawing board.

cr1st1an2• 14 years ago

I don't quite understand HOW does it turn the weight into energy. Could someone enlighten me?

RandallBrown• 14 years ago

the weight is on a string. That string is connected to a crank that turns a generator as it falls.

cr1st1an2• 14 years ago

Oh, and as I understand, the amount of weight is important due the resistance of the crank?

chrisringrose• 14 years ago

Pretty cool idea.

praveenhm• 14 years ago

This is not a new idea. Cuckoo clocks, which is common in germany, works without a battery. we need to pull up the weights everyday.

bobowzki• 14 years ago

If it's real, I wonder if the gears are noisy...

tessellated• 14 years ago

I don't seem to be in the target audience but the first question that came up is: How much noise does it make?

lttlrck• 14 years ago

It's not powered 'solely by gravity'

It's powered by a human lifting the weight.

antidoh• 14 years ago

As we all argue over whether this is powered by gravity, or food, or nuclear fusion, somewhere in a dark hut someone is lifting a weight to attend to the baby that just woke up in the middle of the night.

A $5 Lamp Powered Solely by Gravity

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