Revealed: The Brit-built GRAVITY-powered light that costs $5
An ingenious gravity-powered light source has reached its first funding goal in four days. Co-invented by industrial designer Martin Riddiford - who crafted Psion's hardware - the cheap kit allows an LED to be run for 30 minutes from a three-second pull on a rope. Gravity does the rest. The GravityLight was devised with …
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Portability is obviously the key here. I like the wheel with weights on approach, often mistaken for perpetual motion since it requires an energy input to get it going. But that's hardly portable :)
This is nothing new
I recall seeing gravity powered radios almost 10 years ago working on the same principle - a cord with a large weight (e.g. 10kg) on the end which was slung over the nearest tree or pole. Same principle except for what the generated current is being used for. It's essentially the same as those clockwork radios except the potential energy is gravity instead of a spring.
I assume a light wouldn't draw as much power as a radio so it could either last for longer, or the gravity drop would be less, or some other variation. There are plenty of wind up torches too. Could probably produce gravity powered USB charger too assuming the weight and cord length was sufficient to make it viable.
Clocks that are powered by weights are centuries old. And this light is not powered by gravity. It's powered by the human who lifts the weight onto its hook.
"And this light is not powered by gravity. It's powered by the human who lifts the weight onto its hook."
That much is obvious - but wouldn't fit in a headline. Smile, it's nearly Friday.
C.
Nonsense
It's powered through conversion of potential energy into kinetic into electric into EM - hence by gravity.
The method of initial charging or recharging is irrelevant. Petrol tanks also need to be filled up before they can be used but nobody is trying to say that internal combustion engines are human-powered or gas-station-pump-powered.
Bah!
Wednesday is not "nearly Friday".
Nor is this a "gravity powered light" except if you turn the light itself off and squint. It is a neat idea though.
@Rob Kendrick
'this light is not powered by gravity. It's powered by the human who lifts the weight onto its hook.'
The light is powered by a conversion of stored gravitational potential energy. You are simply taking whatever energy conversion process came before and claiming that that's the one responsible. You could just as easily say: -
'this light is not powered by the human who lifts the weight onto its hook. It's powered by the chemical energy in the food eaten by the human.'
or
'this light is not powered by the chemical energy in the food eaten by the human.. It's powered by the nuclear energy of the sun that grew the food eaten by the human.'
Keep it going!
'this light is not powered by the nuclear energy of the sun that grew the food eaten by the human.. It's powered by the gravitational collapse of hydrogen that initiated the nuclear reactions of the sun.'
So we're back to gravity powered light either way!
Re: @Rob Kendrick
'this light is not powered by the chemical energy in the food eaten by the human.. It's powered by the nuclear energy of the sun that grew the food eaten by the human.' That lay in the house that Jack built!
Re: Keep it going!
The nuclear energy of the sun comes from the fusion of hydrogen to helium .
The gravity of the sun with its mass of 1.989 10^33 g only provide the natural conditions for that to happen.
Reminds me
of John Flynn who invented the pedal radio transceiver in 1928. (That was in Australia, so you may not have heard of him.)
How efficient is the mechanism?
Basic physics tells us that it takes approx 98 joules to lift a 10kg mass up 1 metre - how much of that do we get back? A 0.05 W LED consumes 90 joules over 30 minutes (1800 seconds). Gonna need a big weight or a long rope (and you'd better get good at Olympic-style weightlifting!) to power the average set of LED Christmas lights...
Re: How efficient is the mechanism?
A pully system could allow even a child to raise a great big bag of rocks, pulling a long rope hand over hand (against a safety ratchet) which would still be faster than winding up a torch. It might be better if the mechanical stuff was all made locally and the only thing they has to buy was the efficient LED/dynamo component.
I have one of those espress things they invented
they are awesome!
You do tend to drink quite a lot of espresso if you get one though.
Wind-up Radios
They were created with poor people in mind, who couldn't afford batteries.
But it seems the majority of wind-up radios and torches are on sale in Lidl and Aldi as gimmicks rather than in Africa as really useful appliances.
I fear the same will happen to these lights. The tooling and manufacture already exists for wind-up lights. I don't see how a weighted light with a cord is going to succeed where wind-up technology failed. The real problem with many poor countries is the money they have is spent on AK47s rather than radios and lamps.
Re: Wind-up Radios
They may be gimicks but I have found their larger size makes them more difficult to lose and it's handy when I haven't need to use one for a few months that I don't suddenly find the batteries are dead (but then I only need it for a few minutes at a time).
Re: Wind-up Radios
Batteries are expensive.
Batteries are not nice things to have decomposing into your soil when you've slung them away.
Batteries can't be recharged indefinitely.
Batteries may not be as efficient as this method of energy storage (that recharging batteries get warm is a clue)
Batteries are harder to repair than a piece of rope and sack of stones.
Re: Wind-up Radios
I have a wind up LED torch and I find it quite useful. It's wind up in the sense that there is a handle attached to a dynamo and you turn it for 60 seconds and it stores enough charge for maybe 10 minutes. It's fine for putting the rubbish out or going up in the loft. I have another torch I got in poundland which has a squeeze handle and is okay at a pinch but doesn't hold much charge.
I was once given a Baylis clockwork radio and the thing was more trouble than it was worth. As a radio it had an excellent sound but it only lasted 10 minutes per charge. The windup mechanism packed in after 20 winds and would rapidly spin itself out without charging anything. Gravity should in theory be simpler providing the drop was correctly regulated.
Anyway there is potential for these things in Africa but I think most will just end up being sold with the rest of the shit that Marks and Spencer, Debenhams etc sell around christmas time along - golf ball polishers, fart noise keychains, whiskey flasks, Stig mugs and suchlike. A crappy stocking filler.
I do think tech can help developing nations though. Especially solar stuff - cookers, stills, lights, radio etc. People have to trek for miles to get fuel when they are sitting directly under a giant fire ball capable of cooking their food for them with the aid of a few mirrors.
Re: Wind-up Radios
Your problem is, the drive belt in your wireless wireless has stretched. It can be replaced easily (field-maintainability is designed into the set). The outer case separates into two, and the scary mainspring is concealed behind another tray -- which you don't need to remove just to replace the belt. Wrap a piece of string around the pulleys, and subtract one millimetre for each centimetre to allow for stretchiness. Order yourself a new belt from CPC or wherever, and you should be good to go again.
My Freeplay gives me almost one minute of listening on FM per turn of the crank, with the volume turned up just loud enough to be heard over the sound of the spring unwinding. It's nearer 30 seconds per turn, when loud enough to listen in the shower (radio on the bathroom windowsill; it's not waterproof).
the majority of wind-up radios and torches are on sale in Lidl and Aldi
Well, as far as you have seen. Do you know how many are actually on sale countries where poor people live ?
Re: "Batteries are expensive."
And what do any of your paragraphs about batteries have to do with wind-up radios?
Re: wind-up radios and torches are on sale in Lidl and Aldi
You've misquoted, and then started your reply effectively adding the bit you snipped out.
The correct quote you should have used was, "it seems the majority of wind-up radios and torches are on sale in Lidl and Aldi". I'm going to have to deduct two points from your score on tonight's quiz.
Out of interest, how many are actually on sale countries where poor people live?
Re: wind-up radios and torches are on sale in Lidl and Aldi
I'll take that as a cowardly admission of fault. Ta.
Good Idea But
Good Idea, but need to see if it survives the hash environment/handling that things get in the poorer parts of the world/
Quick question for the usual El Reg geniuses of which there are many. As the device is self powered by the weight of the sack, would it be possible to use some of that power when the sack reaches a certain point to bring the sack (slowly) back up to the top to release it again, possibly with a counter weight on the other side which starts to go up when the one goes down, possibly equal weights and using tiny amounts of power to allow one side to go down rather than staying equal? As long as it generates more power than it uses it should be able to ensure the light stays on as long as required rather than for 30 minutes or an hour?
Or a spring at the top, the bag on one side goes up and the other goes down, when the bag reaches the top it runs in to the spring which when compressed enough releases the force which starts to push the bag down and pulling the other bag up? As both bags are equal weight it would still require a little bit of power to stop it from stopping in the middle, but again, if it can generate more power than it uses it shouldn't be an issue.
Nice try, but you can't fool Physics that easily. You have to get really small or really fast to do that.
"generates more power than it uses"
Congratulations you have just invented perpetual motion. Have a nobel pint on me.
You are over 100 years late with that idea.
Back when you could actually patent a perpetual motion machine as a power source it would have gone down a storm.
Hint: The energy required to get the bag back up is exactly the same amount as it gave you on the way down, assuming a system with no losses (tough shit there too). Thus there's nothing left to run the light......
Re: David Webb
"....As both bags are equal weight it would still require a little bit of power to stop it from stopping in the middle, but again, if it can generate more power than it uses it shouldn't be an issue." Don't be silly, the idea of a cat with a piece of toast with the buttered side down strapped to the kitty's back makes a much better perpetual energy generator! (Evidence for this theorem to be found here (http://www.flycatfly.com/flying-cats).
In seriousness, it may be technically feasible to design a counterweight system to prolong the action, but it would add massively to the complexity of the device, its cost and possible problems in operation, whereas getting Mrs African Wife to scream at the kids to lift the bag again is a lot simpler and more economic.
Oh yes, that old perpetual motion machine
Unfortunately the universe likes to nick power out of everything, in this case through friction (which ends up as heat). What you are describing is a unity power system, which seems to be impossible.
Seriously?
You've just invented a perpetual motion machine. I can't see any flaws myself. :-)
On the off-chance you're actually completely serious, no, it is impossible. For it to work would break several laws of physics, as any 14-year-old physics student should be able to explain. If you don't have a 14-year-old to hand, here goes:
In the light, the energy to power the LED comes from the food a human eats. His or her muscles convert this stored chemical energy to motion (kinetic energy) to overcome acceleration due to gravity and lift the bag from the floor to the top of the rope. The energy is stored as gravitational potential energy in the bag at the top of the rope. As the bag descends, this gravitational energy is converted back into motion (kinetic energy) . This kinetic energy is converted by the mechanism into electrical energy and that electrical energy is converted into heat and light by the LED. Apart from the fact that some energy is lost to the environment as heat (largely due to friction) at each stage, once the energy has been converted to heat and light by the LED there is no way to convert it back to the energy required to lift the sack.
No - what you are proposing is a perpetual motion device and such a thing is not possible.
The sack, upon being raised, has a certain potential energy. When released, the energy is converted to electricity. Energy is lost in the system through friction, transmission losses, conversion losses etc. You could use some of the energy to raise another weight but you'll never raise it as high as the first weight was raised. And if you raise another weight then you have less energy available for running the light.
You can change the length of time the device will create light by altering the gearing, the weight in the bag and the efficiency of the conversion system / LED. Adding reciprocal weights won't do anything useful.
I'd love to hope
that this post is being gently satirical of the quality of El Reg genius thinking that we so often see. But...
Deep breath ....
"... if it can generate more power than it uses it shouldn't be an issue."
If it actually could do that, it would be an enormous issue. Anyway, the perpetual motion machine has been invented (or 'designed') many times throughout history. For some reason, a working model has never been constructed.
I think the Law Of Conservation Of Energy may be a barrier here
perpetual motion machines do not exist
All you need to do is moderate the speed of the fall and/or the length of the cable pull.
I do suddenly wonder what the efficiency of a block and tackle is....
Quick question for the usual El Reg geniuses of which there are many
But sufficient non-genii to respond to a fine bit of trolling.
98ish joules to lift a 100N (10kg) bag by 1m. in a lossless system you would need 98ish joules to bring it back up. That would leave no energy to power the system (LED). You would need three bags to power the system (LED) AND return one bag to the starting position. Better to put two bags on to begin with and drop slower.
"if it can generate more power than it uses"
You would be a very very rich person indeed if you could figure this out.
Re: perpetual motion machines do not exist
Generally the Actual Mechanical Advantage you get from the Block and Tackle is some amount less than its ideal Advantage (which should be a factor equal to the number of pulley pairs in the set). Friction generally accounts for most of the loss.
@David Webb
If that was a genuine question, I guess it is simply confusion on your part, and teh downvotes are ungenrous rather than enlightening. The point where your vision falls down is this:
" As long as it generates more power than it uses"
By definition it will always generate less power than it uses, and that power is being used to keep the light on. You can't use the same power to both lift a counterweight AND keep the light on.
Upvoted
Cos at least my sense of humour is still functioning. Joke alert for the overly literal.
Hrm?
I'm pretty sure I didn't mention perpetual motion, more along the lines of a see-saw, at the moment it's half a see-saw with the one side dropping and staying down, but with a see-saw you put force into one side (that'd be the start with the human bit) and it doesn't just stop, it keeps going until the other forces catch up with it and stop it extending the uptime of the light past 30 minutes. That is what I was asking about possibility, not the possibility of keeping the light going for eternity which would be a pretty silly thing for a light to have to do in a persons home, or shack.
Though in fairness I did invent what I think is a perpetual motion engine about 5 years ago, but I'm still running tests on it before I can actually conclude it is a perpetual motion engine, once it stops I'll be able to give the definitive answer........
Not ideal
I'm all for any advances to help out people in the poorest situations, however I have a couple of problems with this design having worked in Africa.
1. Dust, the clockwork components will jam easily.
2. Getting up every 30min to lift a very heavy bag will be a problem for many.
3. if it can only power a LED for 30min, that connection isn't going to be much use for charging a mobile phone or anything else.
4. pump action and wind up torches have been around for years, cost less than $1 and are portable.
He was originally tasked to create a cheap solar light to take advantage of the abundant solar resources available near the equator, and I have to ask, why aren't the people who originally tasked them supplying the funds they're now chasing? Probably because they ignored the brief, but there may be other reason too.
This appears to be western thinking along the same lines as "lets just give every person a mozzie net!" which results in the nets being used as fishing nets which is destroying the fish stock in rivers and especially Lake Tanganyika as mosquito nets will capture everything not just adult fish.
The most impressive achievement in this arena is with Corus (now Tata) and their PhotoVoltaic Paint, however it's still at least 5 years away from being available.
So it's like clockwork, or old-fashioned grandfather clocks.
And it might produce LED light for the stated 30 minutes, but we're still talking about the same amount of power as lifting a weight up a metre or so. That takes it into tiny amounts of power that can also be stored in clockwork or, say, an even-cheaper, mass-produced, rechargeable battery. "Environmentally-friendly" once in operation, yes, but hardly "bringing light" to anyone who doesn't already have it (and it's doubtful that the cost of creating and shipping the device is actually doing much that is overall positive environmentally, especially with the LED's and the strength of components to hold the weight steady).
It's clever and we can all go "wow", but I just don't see the market. Even the clockwork radio died a death:
"After Baylis lost control of his invention (the clockwork radio).... units switched to disposable batteries charged by cheaper hand-crank generators." (and although you might own a clockwork torch, like a lot of people, when was the last time you owned one that didn't use rechargeable batteries in it or that actually was worth the hassle to wind up for the amount of light it gave compared to, say, just about anything else - batteries, electricity, kerosene, even a lit-match? Last time I tried to use one, I got tired of having to keep cranking it - because it hadn't been cranked regularly and the internal battery was not holding a charge well - while trying to do a simple job in the fusebox and ended up just putting a battery torch down the hole)
I think we're over-simplifying and under-estimating people in third world countries here if we think that they need these sorts of things so desperately - like the "bottle in the roof" lighting... are you honestly telling me that people sat in the dark rather than collect a piece of broken glass, or even just put a hole in the ceiling? Maybe it just wasn't that important to them? And that particular invention required plastic bottles (probably harder to find than just "something clear to cover the gap"), water and bleach (to stop the water going green) and only worked, shockingly, in daylight. So it was a pretty hole. It's like the "spoon made from a fork pushed through the bottom of a polystyrene cup" image that roams the Internet - clever if you think of it on-the-fly and get to use it that once, but I can't see quite what problem it's solving long-term that doesn't have a better solution.
If you desperately need lighting from a bunch of low-power LED's and are willing to stumble around in the dark with a heavy weight to get it, I'm sure you'd be equally as chuffed with an solar-charging-LED torch - the kind of things we give away with Christmas crackers now. And I'm not at all sure that something you routinely have to move kilos of weight (from a suspended hook) by hand to activate would last even as long as the torch would, in terms of sheer robustness (I'd give it a month or so of constant use before the gearing went).
The real benefit of this new device is that it can be left on a shelf indefinitely with no worries about battery leakage etc. So it's an ideal thing for people like OXFAM to include in emergency kits. Take the kits to people who have just suffered a disaster / been displaced by fighting and they can just rig it up and have some light in their emergency accommodation. No need to have relatively expensive stuff like solar panels or batteries in storage.
Some people hereabouts are looking at things with a western, nice safe / warm home view.
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