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Microwind Generator For Low Power Systems
An anonymous reader wrote in to say that "Shawn Frayne, has developed Windbelt,
efficient, cheap lowpower wind generator built out of taut kite fabric." Everyone has seen the video where the suspension bridge is ripped apart by wind- his idea was to use the same thing to generate power. I doubt I'll be running my desktop off it any time soon, but it's a cool idea.
And now for a really interesting renewable energy concept: kite gen. Would have made Newton smile :)
They who would give up an essential liberty for temporary security, deserve neither liberty or security - Ben Franklin
...but it is not at all clear what their efficiency or $/Watt or manufacturing cost will be. Although absolute efficiency is maybe not critical for many applications given that the wind is free, cost is important in, for example, third-world deployments.
See the discussion here for example: http://www.fieldlines.com/story/2007/10/13/9445/4984
Much as I'm intrigued by this let's not get into perpetual motion machines nor "beating Betz" just yet! In particular the "30x as efficient as the best microturbines" claim in TFA is particularly suspect: I have a VAWT made from a cardboard cereal packet in my back garden that probably extracts 10% of the available energy.
Rgds
Damon
http://m.earth.org.uk/
What did they teach it? Um, Editors, I think the word you're looking for is 'taut'.
You can learn a lot about a person if you just take the time to inject them with sodium pentathol
So will the power output be measured in bridges per minute?
(In fiction at least) The Subways Of Tazoo, Colin Kapp, 1964. In the story, it was strings rather than ribbons. The story involves an alien race that killed themselves by climate change. Tsk, what science-fiction twaddle!
One line blog. I hear that they're called Twitters now.
This turbine was one of the items mentioned few days ago on Slashdot in another post. See: http://science.slashdot.org/article.pl?sid=07/10/11/212243
The only sure way to help countries of the third world is for countries like the US to open up their subsidized markets. The corn market in the US for example is subsidized to an extent of almost 10 billion dollars in 2005!
If third world countries got just half of that market, a lot of lives would be changed.
Shawn Frayne's Windbelt Wins Popular Mechanics 2007 Breakthrough Award
One line blog. I hear that they're called Twitters now.
Not too dumb. He was designing it for use in Haiti. While I suspect there are places where nothing is tenable, a thin ribbon under tension is a whole lot simpler and cheaper to manufacture and maintain than a rotating wind turbine. It doesn't have to be mylar, you could use scrap cloth, although mylar may last longer and be easier to keep under tension. LED's were for the demo. You could use the thing to run any light; or better yet charge a small battery so you have power on demand.
He made another good point in the article: If you break this you have something that a local can fix. If you break a solar panel, your stuck with a broken panel (which is trash). What he didn't mention is that this would run at night too, as opposed to a solar panel that only works during the day.
while I agree with another poster's comment that the 30x improvement in efficiency over a microturbine is probably not real, I think it's fairly interesting. Enough so that, since IAAAP (I am an applied physicist), I'm thinking about building one myself to get some numbers and see how well it scales. I know some people in Africa who might be interested in something like this...
There was not any engineering detail to go on from the video, I agree. But trashing the idea without getting the numbers is bad science, more akin to the nightly news.
The whole concept is interesting, because it can work with wood and cloth instead of mylar and aluminum. The "first world" part would be the magnet, coils and the DC rectifier/converter to allow a user to likely charge a battery.
How many of these generators and how big they would be to extract a usable 10 watts of charging power in a 5-10 mph wind hasn't been defined, but with a couple models, that can be determined.
You never learn anything by bitching. Buckling up and testing is the way this & other ideas will be understood and improved. For the 3rd world, just a minimal LED lamp array can make the difference between studying at night or not.
What he didn't mention is that this would run at night too, as opposed to a solar panel that only works during the day.
Sure, but this will only run when there is wind. In any case you are going to need some kind of energy storage, whether batteries for small scale use, or pumped water for larger scale.
With a small scale system like this, you could also combine it with solar panels and a battery and get luggable power generation that would work in most places.
I'm thinking about building one myself to get some numbers and see how well it scales
Cool! I'm sure a lot of people would love to see a project page for a DIY wind generator of this sort!
My guess is that generators in series can't easily be synchronized, but generators in parallel would tend to self-synchonize (assuming near-identical construction and side-by-side location).
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It's so Popular Mechanics. Another resonant oscillating generator.
This is an old idea, but the usual form is a free-piston engine. Popular Mechanics was hot about that one back in 2004. For something that will light two LEDs, that thing looks big and expensive. Note the machined aluminum frame. For comparison, here's a toy wind generator kit ("convert a plastic bottle to a wind generator!").
Notice how the guy with the vibrating ribbon generator demonstrates it in front of an electric fan. On high. That's probably because it only works in a strong wind. People generally don't live where winds are regularly that high. Wind speed in Port-au-Prince has been between 9 and 12MPH all day, so something that cuts in around 9MPH is needed for use in Haiti.
The classic cheapie generator is taking an oil drum, cutting it in half, and using that as a Savonius rotor. Then you get an alternator from a car, and there's your actual generator. The axle sticks up into the air, where the halves of the oil drum collect the wind and turn the alternator. Here's a smaller version.
The reference to the Tacoma Narrows bridge is very relevant. Galloping Gertie showed that even without hurricane-force winds a very heavy ribbon-shaped strip can me made to move in an extreme fashion due to mechanical resonance. Even a small strip would have the same kind of resonance so that large relative movement can be extracted from even light winds.
Haven't you ever made a blade of grass whistle between your thumbs?
If you don't want to repeat the past, stop living in it.
"but now I see from the Wikipedia article that resonance has nothing to do with it"
Did you read the whole article, because you seem to have missed this part,
"The wind-induced collapse occurred on November 7, 1940 at 11:00 AM(Pacific time), due partially to a physical phenomenon known as mechanical resonance."
I only go to buffets for the unlimited soft serve.
I'm not saying that this is the greatest thing since sliced bread, BUT... Those who think a thing to be impossible should shut up and get out of the way of those who are doing it. You can waste your time cursing the darkness, but it's probably not going to be as productive as trying to light a candle. Or an LED.
You could use the thing to run any light; or better yet charge a small battery so you have power on demand.
I got a couple of battery re-chargers for AA - C and 9 volt, and started recharging for all my flashlights, MP3 players, and such a few years ago. Last year, I rigged them to a small solar array, so those apps are now completely off the grid. I cold probably have used a very small wind turbine just as well, or an adaptation of a widget like the one in the article. With a good supply of batteries, I can afford to wait a bit for a sunny day, so solar's what I went with. I doubt I'm saving the environment much, if at all, given manufacturing costs of the devices, but I keep seeing the whole idea dismissed on the basis of that one argument about ecological fitness, or related argeuments about scaling.
Meanwhile, if the local power grid goes down for a day or three, I have some things which will still run, including a bit of light and an emergency radio.
It's like another, 1,000 year older tech adaptation. I also have a fireplace in my house. I don't heat with it on any regular basis, but I have a hinge mounted, cast iron widget with a hook on the end that can swing over the fire, so I can cook over it pretty expediously. The fireplace is never going to be an energy efficient way of routine heating for millions of people now using gas or electric heat. It doesn't fix any of the current problems related to old infrastructure, global warming, and overpopulation. Scaling arguments are actually negative (if we all go back to burning wood, we'll screw up the environment more, not less), but my fireplace will keep a few people warm or a very cold night without power, and even give them some hot soup or cocoa. If we do have a lengthy outage in the winter, The chimney's clean, I have a couple of ricks of wood already cut, and an axe if I need more, and we'll probably not just manage for ourselves, but put up the little old lady across the street on our couch, take some hot soup to another neighbor or two, and so on. Plus the radios mean I'll know what sort of problem it is early, and can plan. I'll know if the problem is expected to last long enough that I'd better conserve the chainsaw for real emergencies, etc.
I'm not even sure but what that IS a potential huge net ecological savings. People who cope on their own if the big, gridded systems go down aren't as likely to be a drain on emergency services. What's the carbon footprint of a helicopter rescue operation?
I'm starting to think scaling arguments are mostly rubbish anyway. Whenever we start addressing scaling, we're talking about getting up to sizes where someone can centralize the production, and rent services to the common people. A stable, long term sustainable, ecologically sound system shouldn't assume centralized control is desirable, in fact, all other things being equal, it's a bad thing.
Who is John Cabal?
Wind power is very well understood. The power in the wind is (1/2)*p*A*v^3. Where p is air density in units (kg/m^3), A is the swept area in units (m^2) and v is the velocity of the wind in units (m/s). This is intuitive from a physics perspective if the energy of a moving object is (1/2)*m*v^2 then p*A*v is mass. Albert Betz proved that the maximum efficiency of a wind generating device is 59%. Many small wind turbines can achieve an efficiency of over 30%. From the article it says "his device [is] 10 to 30 times as efficient as the best microturbines" That would put the efficiency of the device at at least 300%. Not only is that higher than the betz limit it is higher than the energy available. A quick example. Lets use an air density of 1 and a swept area of 1 (for a rotary turbine this would be a blade radius of .56m), a wind velocity of 10mph (4.47 m/s) and an efficiency of 30%. This will make 13.4 watts of power. That would be enough to power several small led light.
Probably, but the mass and viscosity of the water would dampen out the vibrations, making it not very efficient (very low frequency).
One of the neater aspects about this project is that you can build it out of trash you have laying around. Salvage magnets from headphones or speakers, salvage magnet wire from a motor, build the frame out of whateverthehell you have laying around, and use a strip of waxed silk or something for the ribbon. You need a little bit more know-how to turn that into DC, but that's also very basic, and the components could also be salvaged from just about anything. Hell, same thing with LEDs. Let's face it, people in the third world are superb scavengers -- look at the sudden proliferation of satellite dishes made from hammered-out cans that popped up in Afghanistan after we toppled their regime.