Brit inventors' GRAVITY POWERED LIGHT ships out after just 1 year The British-designed Deciwatt gravity-powered lamp is now in production and shipping, a year after the project went public. It was conceived by Martin Riddiford and Jim Reeves of industrial design outfit Therefore, which is best known for clever mechanical designs including the Psion computer keyboard. Therefore invited The …
Some while back I did wonder whether lifting up big weights is a useful energy storage mechanism - for example, use solar/wind while its there to lift a bloody great bit block of concrete, then use the potential energy during the night. But the weight you need to lift to get any decent storage is much too large to make it useful.
Ok at this small scale where you are powering low power LED's, not so good as a general purpose storage mechanism. Shame really.
"Some while back I did wonder whether lifting up big weights is a useful energy storage mechanism - for example, use solar/wind while its there to lift a bloody great bit block of concrete, then use the potential energy during the night. But the weight you need to lift to get any decent storage is much too large to make it useful."
Several hydro powers in scotland do exactly that - Cruachan for example as covered by El Reg:
http://www.theregister.co.uk/2013/07/23/reg_man_delves_deep_to_find_the_power/
Pumped-storage hydroeletric does pretty much what you say - they pump water up into a higher reservoir during low-demand periods, and release it on demand or during peak periods. There are at least two that I know of in the UK (one in Scotland, one in Wales) and act as Grid reserves
http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
In days gone by one relatively small central steam engine would puff away forcing water into a vertical hydraulic ram with a huge (several tons ) weight on top of it. The stored potential energy could then be released far quicker in bursts to operate such things as hotel lifts ( London Hydraulic Power company) or dockside cranes..
Yes, aware of the hydro schemes, I was wondering really how small they could get and still be useful. The answer is not very.
And thanks for the hydraulic accumulator stuff- IIRC this is what William Armstrong (of Cragside and hydroelectricity invented - nice link up there)- that's a good biography for those interested in that sort of thing.
Clearly there will be a spinning magnet of some sort in a coil of some sort, but I suspect that the "proprietary" word will actually refer to the method by which the mechanics work to stop the weight plummeting to the ground and to compensate for different weights hung from the device, while still producing the same output voltage.
My thoughts exactly.
I wonder why they went for the descending weight method, versus a coiled spring that you crank to tighten up, like the old fashion wound-up clocks (& toys). With a mechanical regulator, the dynamo could be spun at a reasonably constant speed to generate juice.
"I wonder why they went for the descending weight method, versus a coiled spring"
I suspect because you can just lift the weight up and re-attach it in a fe seconds rather than spending 10minutes winding a spring backup. Also, both the weight/bag and the rope are easily replaced. A heavy duty coiled steel spring not so much.
Springs are expensive in production environments.
Not just the springs themselves, but you've got to have at least two attachment points which means molded parts or drilled holes and they are probably the most difficult parts to deal with on a production line.
Throughput can decrease 5x per unit easily if the spring is very small or has any sort of force. A one pound coil spring is an absolute bear to deal with. The only workarounds are custom spring setting devices but that means at least one person loading the device or ordering prebuilt custom sub-assemblies. So at a minimum you've doubled the labor required as well as taken on tooling costs and line speed is still slow or your parts cost has just skyrocketed.
If springs can be avoided in production it is usually best to do so. Especially in cost sensitive products.
Well, the belt and hook look "proprietary". When either break - which the belt will, sooner or later - it isn't going to be easy to cobble something together from stuff easily found in the places that form the market for the gadget. The tolerances (hole centres, thickness of belt) and materials performance (deformation etc) appear to be important. It isn't obvious how the belt would be changed in the field, either. I hate to be cynical about this, but it looks as if the manufacturers have made sure there will be a steady revenue for spare-parts.
There's less than zero money to be made in spare parts for a unit that sells for $10. It would actually be cheaper to give them a complete replacement unit than deal with scalable spares.
If you're dependent on parts for profit it means you have to stock not just parts for production but parts for spares as well, it's a second business. While not quite doubling, you're adding at least a 30% cost to your overhead as well as the costs of logistics and warehouse personnel. The spares inventory has a far higher value because it can't be used in production but you've already paid for it so its very existence costs money. On top of that the costs of shipping the part would exceed the price of the complete unit.
You can do OK on parts and subassemblies for expensive and complex systems, like cars, that have high volumes of production so inventory doesn't get as stale. But with cheap products, like this lamp, the costs of spare parts are higher than the complete unit. It simply doesn't make any sense to do spares on an item like this.
Very little I would guess except for the energy storage and recharge method.
Once the energy is "stored" either in a coiled spring or a weight high off the ground, its release will be governed by a few gears and a governor wheel (basically a gear with big fins on it). Couple this regulated rotational speed to a dynamo and you have power until the stored energy runs out.
To my mind it's not exactly innovative, in fact it's verging on the Apple level of obvious, but hey, if nobody else has built one, good luck to them.
I'm sure they'd be able to get dozens of patents from the US patent office.
"Were I to design this I'd use something like a torque converter."
Better yet, a DC to DC voltage converter. You tweak the conversion ratio to keep the generator running at a peak efficiency point while providing constant output current (to an LED array) or constant voltage (to charge a battery). The firmware, once developed, is much cheaper per unit than knocking off copies of a mechanical device. The microcontrollers can be had for pennies apiece.
Spring powered devices have been around for years and there's no mechanical governor wasting energy. A switching power supply is used with an inverted feedback loop. When there's too much output power, the switching power supply increases the output more. This burdens the spring/weight so that it slows down and produces less energy. When the output is low, it decreases the load and the spring/weight speeds up. Of course it's not very stable but one more layer of power conditioning is trivial when you're in the milliwatt range.
Although I'm sceptical about the balance of cost, input and output. Even with LED's, 0.1W doesn't go far, and I can see people deciding that 13c a day is an acceptable price for light rather than have the lights keep going out every twenty minutes.
We already have LED torches that already claim to deliver 1W for 20 minutes from one minute winding a tiny crank, and in some cases integrating a small PV panel. Admittedly that's sixy seconds effort, not the three seconds to lift the weight, on the other hand it's ten times the light output. I can't help thinking that a better solution would be something the size of a gas lantern, using the wind up torch tech scaled up with a larger crank and capacitors, so giving perhaps an hours light at 1W from one to two minutes of winding. Smaller, more portable, closer in form and function to the lights they are intended to replace.
The deluxe version powers a light bulb all night. It comes with a really long rope and you hoist it up to a pole sticking out of the top of your roof.
The non eye-sore version comes with a really long rope with a bucket onthe end. You dangle it down a well. If you need less power, butto last longer, you use the bucket only half full.
:)
"13c a day is a lot of money when you live on $1-2 a day."
Yes, but it's a two year cash pay back, and when money's short the discount rate rises disproportionately. That won't be how the target market express it, but it's the same principle that sees poor people paying 1,000% APR on payday loans in this country, or higher rates to loan sharks around the world.
That's why the inventors discuss lease type schemes, but the harsh reality is that this is too expensive for what will be a pitifully low light output. Many of the prospective users will also be buying kersoene for cooking, so why buy a one candle power device that you have to fart around with every twenty minutes when you've still got to buy kersene, you've already invested in a kersoene lamp that gives better light for longer, and the time value of the money means more like a three to four year pay-back?
If you look at energy efficiency schemes in the UK, people are hugely reluctant to invest in things that save them money, even when they do pay back. Take GU10 halogen bulbs - in a well used room replacing these with LEDs will give you a payback of about one to two years. Despite the fact that nobody is offering savers a 50-100% interest rate, most people are still buying and using halogens. Or look at the humungous flop that Green Deal has been. Even the health and safety benefits are of little appeal. In the developed countries the benefits seem logical and obvious. But in countries with high infant mortality, non-existent health care, roads like something out of Death Race 2000, and subsistence living subject to famine (ignoring unrest and civil wars), the H&S benefits of an LED lamp over a kersosene lamp count for nothing.
The problem here, is that the device offers inferior performance to that which it is supposed to replace, and requires a significant investment. Innovation has to do things better or cheaper, or both, and I'm afraid I don't think the inventors set their sights high enough. Everybody would like this to be cheap and effective, in reality it is neither, and the sum that gives a net benefit only works when you aren't seeing things from the perspective of the intended users.
Clever use of technology, which is what developing countries really need. There's a company in our village that uses solar to charge off-the-shelf battery systems. With some clever monitoring and computer systems, they get enough power to light a small village (allowing kids to study at night, without using kerosene lamps that cause huge numbers of fires) and run a fridge to keep vaccines cool. If battery power runs low, the computers dim/turn off the lights to keep the fridge running. They go round installing these kits in remote African villages - real genius.
I'm confused how 0.1W is any use for charging anything?
Otherwise it's a neat idea although even for lighting 0.1W seems very low indeed... what is a very efficient .1W buld equivalent to in old-fashioned bulbage?
If 20lb is a problem to lift, a simple block & tackle would be a low-tech solution.
"what is a very efficient .1W buld equivalent to in old-fashioned bulbage?"
For a good LED the bulb is about 4-5x more efficient than a halogen bulb (eg for a GU10 you're talking about a 5W bulb being equivalent to a 35W halogen). Then a halogen bulb rated for 1,000 hours will be about thirty per cent better than a simple incandescent filament, so say 6x all in. So from that comparison we're talking about 0.1W LED being equivalent to say 0.6W in old money.
Another way of looking at it is to consider that you'd get about 10-15 lumens from a DC 0.1W LED light. A traditional 60W bulb gives 800 lumens, which (on a linear basis) implies a similar half to one watt.
Put in more obvious terms, we're talking about one candle power of illumination.
What happened to those hand-cranked or hand-squeezed torches?
They cost far less than this - indeed they were being given away as promotional gifts by companies - are far less cumbersome, and the way I see it, could achieve much the same outcome, if not better, with less hassle and outlay. I used to have one myself.
Wouldn't something like that be more convenient than this latest amazing contraption with its secret converter of potential energy into electric energy? And why isn't it in widespread use / or is it?
They may cost less, but they have poor quality plastic gears which break all the time. They are novelties really and require quite a bit of work to get them going, with this you hook up a weight and that's it. With had cranked torches it's 20mins of cranking to get a reasonable amount of charge.
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