Vertical Axis Wind Turbine With Push and Pull 374
Sterling D. Allan writes "After 10 years of prototyping, wind tunnel testing, patenting, and tweaking, Ron Taylor of Cheyenne (windy) Wyoming is ready to take his vertical axis wind turbine into commercial production. Design creates pull on the back side contributing to 40%+ wind conversion efficiencies. Because it spins at wind speed, it doesn't kill birds, and it runs more quietly. It also doesn't need to be installed as high, and it can withstand significantly higher winds (can generate in winds up to 70 mph, compared to ~54 mph tops for propeller designs). Generating costs estimated at 2.5 cents per kilowatt-hour, putting it in the lead pocket-book-wise not just of wind and solar, but of conventional power as well. Production prototype completion expected in 5-7 months."
Birds... (Score:5, Interesting)
The whole bird thing sounds like a convenient excuse invented by people who really oppose windmills because of noise or land use issues, but want a fuzzier, more PR-friendly excuse. The kill zone on a windmill is basically going to be the circle described by the rotor tips as they go through the air, so it's not a huge zone (as you get towards the center they're not moving as fast, tangentially) and at any given time it's not as if just flying into that ring would result in death, you'd have to be at a point at the particular moment in time when the blade moved through it. Last time I checked, birds don't hover, so you have two moving objects that would have to compete against some long odds to end up in the same place at the same time. Also, the turbines are noisy as hell -- something which is a legitimate criticism -- and I find it hard to imagine that birds wouldn't be scared off by the sound, air currents, and motion. (Actually they wouldn't make a bad large-scale scarecrow over farmland...)
Call me overly cynical but I find that particular objection dubious.
Re:Could be useful for microgrids (Score:1, Interesting)
Not stated was variable pitch propellers have lots of advantages too - no clutch. His design implies a clutch, and we know both brakes and clutches wear out.
In the meantime, cows, dog, cats and rodents who try this revolving door will get what they deserve. With propellers up high, you dont need a fence.
Note to critics and skeptics (Score:3, Interesting)
Like a lot of other technologies, this one is going down in price in a predictable way. Check out the wind energy data [earth-policy.org] at earth-policy.org, especially that last figure.
The sector has recently been experiencing Hockey-stick growth [worldchanging.com] in investment. It's pretty much inevitable that this is going to be cheaper than coal- and likely cheap enough to make hydrogen for when wind is low. Cheap, guaranteed price, non-polluting.
Judging from nuclear's track record, it won't come close to wind. These turbines might not be the ones to put nuclear out of its misery- but wind certainly will play a large part (don't discount solar just quite yet).
Re:Could be useful for microgrids (Score:4, Interesting)
In case anyone else is interested in what a Savonius windmill is, there's a page with a little simulation of one here [picoturbine.com]. I think they're selling something (model turbines maybe?) although I didn't really check it out.
I have to wonder though whether one of these is really as efficent as a propeller-type windmill, given that a propeller type one can alter its blade pitch and keep the rotational speed relatively constant in different wind speeds. Is there a way to do that with a Savonius design? It doesn't seem like the airfoils are really anything that you could easily change in flight.
I'm not sure if it's true, but I once heard an interesting factoid about Dutch-style propeller windmills, and how they were among the first mechanical devices to implement a "feedback loop"; you have a tail rotor mounted perpendicular to the main rotor, which drives the mechanism that orients the windmill. If the wind isn't blowing at the mill directly from the front, it causes the small rotor to turn, turning the mill into the wind. When the mill is pointing in the right direction, there's no wind on the small rotor, so it stops. Pretty brilliant, for the 17th or 18th century.
Re:Sorry... (Score:3, Interesting)
This has been an epic last few weeks for the ability of crackpots to get pseudo-science posted on here. I suspect its actually just a game the editors are playing -- trying to see how riled up they can get everyone. I suppose, though, its possible its just another example of why Slashdot either needs new editors or story moderation.
Been there, done that (Score:1, Interesting)
http://www.control.auc.dk/~zinck/papers/SoA%20WT%
Re:Could be useful for microgrids (Score:3, Interesting)
From my readings, and as a pilot, I can hazard a guess that this is because of the enormous complexity both in manufacturing and in maintenance of having a variable pitch prop. The money that you save (earn) through increased efficiency might be gobbled up the first time you have to higher a technician to climb to the top of a 200m tower and fix a faulty blade. Don't know if this is the only reason, but it's certainly a major one.
I'm not sure if it's true, but I once heard an interesting factoid about Dutch-style propeller windmills, and how they were among the first mechanical devices to implement a "feedback loop"; you have a tail rotor mounted perpendicular to the main rotor, which drives the mechanism that orients the windmill. If the wind isn't blowing at the mill directly from the front, it causes the small rotor to turn, turning the mill into the wind. When the mill is pointing in the right direction, there's no wind on the small rotor, so it stops. Pretty brilliant, for the 17th or 18th century.
Never heard that before, but it sounds pretty cool and feasible. It makes sense if you consider that bearings would have been pretty difficult back then, and thus you might not be able to rely on a little tail flap a la weather vane for orienting the mill.
Flawed (Score:4, Interesting)
Also, bird death is about 1 per turbine per year for current technology. This is about 9 orders of magnitude less than bird death from buildings/vehicles/airplanes etc., and that's not considering the enviornmental consequences on bird life of NOT using renewable sources...
Dumpy little vertical axis machines may have limited uses in isolated installation, and for revolving advertising, but they are not practical for large scale generation. The rotor of a modern 5MW wind turbine is about the same size as an athletics track. Imagine how big this vertical axis machine would have to be to match the wind capture of this. If the alternative is to have many small devices, there would be a very large number indeed: this carries costs of electrical interconnection, massive maintenance overhead from trillions of puny alternators and gearboxes, all of which was probably ignored in arriving at the 2.5 cents per kWh.
The only way to make money with this turbine is to be the poor guy's patent attourney.
Re:Directionless (Score:2, Interesting)
Actually, the blades are always moving agains a relative wind. What's tricky about the aerodynamics is that the relative wind constantly changes as you go round the circle. The solution to this is to spin faster, so that the wind component which changes (the real wind itself) is small in comparison to the wind component which doesn't (the relative wind produced tangentially to the spinning blade).
Of course, as you spin faster, you get more centripital forces, and if you go too fast, everything fall down go boom.
Re:Could be useful for microgrids (Score:5, Interesting)
Roughly, power = 1/2 * rho * v^3 * a * k * c
where rho is mass density of air, v is windspeed, a is area, and k converts all units to power units. If you use square feet and feet per second as units, and 0.00238 slugs/ft^3, then you need to know that 550 ft-lbs/second will convert to horsepower. "c" is the conversion coefficient, typically around 0.25 for a good bladed rotor, probably closer to 0.1 for a savonious. I have built and seen rotors that did better than 0.3. Factor in loss due to generator power conversion, transmission line losses, etc, and things go downhill from there.
In general, there is a Betz limit that says, mathematically, that the most you can ever harness from a fluid flow such as wind is 59%, though there are suspected ways around that. When these people deride "tip speed ratio" they are giving up the fact that, when you can travel faster than the wind, as does the outer regions of a bladed turbine, you have the opportunity to generate more power due to the lift-to-drag ratio of high aspect ratio blades (wings) providing lots more torque than you would get by mulling along at around the same speed as the wind. Take a look at those multibladed farm water pumpers. They have a tip speed ratio rarely greater than one, and their conversion efficiency is fairly low. They're good for high starting torque to lift water. In electrical generation, you don't worry about starting torque because generators don't "kick in" till you're flying fairly fast. There is one aspect to the claims in the granted patent: he adds external "airfoils" to direct more wind into the central sevonious rotor, speaking of which, it's hard to tell from the pictures, but he may miss one nice point about generalized savonious rotors: the gap in the middle. If he closed that, he loses a lot due to the "airfoil" effect of the retreating (driving) blade directing some of the airflow through the gap into the advancing (dragging) blade (cup if you like).
In some sense, what he claims in his patent is well known in prior art. It's a lot like those dumbass patents the USPTO is granting these days for stuff like "one click", or "shopping carts" -- those folks in the USPTO never go outside and smell the roses. The patent presently granted can be stomped all over with photos from even ths us department of energy archives.
Dumb stuff like this comes along all the time. I don't think this is the work of a charlatan; rather, it really appears to be the work of an honest, but not well educated fellow. Clever, but not original or novel (novel to him, not to the rest of the world). Too bad every time someone comes along with a perpetual motion machine or something close (really cheap energy), they have to slam everything else that's already out there.
An earlier poster here commented on the apparent low quality of the website that printed the press release. Too bad about that. I'm reminded of the somewhat childish but good hearted efforts, long before the web, in the late 70's following the huge gas pump crisis in the U.S. Everybody and his uncle started printing journals, whatever, including The Mother Earth News. Some of it was good, some of it was rubbish, but we all had a ton of fun doing it. Looks like what goes around comes around. Again.
Jack Park
Re:Note to critics and skeptics (Score:2, Interesting)
These 2002 data are from the Utility Data Institute (http://www.platts.com/Analytic%20Solutions/UDI%2
Production costs for a non-production system are never right (remember "too cheap to meter"?). But there is no question that wind generated electricity can be competative in cost, and that's one reason you see increasing growth. With 1 MW wind turbines and a constant breeze Germany could generate all of their current electical needs with 320,000 turbines spread out over their 350,000 square kilometers of land.
Re:Sorry... (Score:5, Interesting)
Vertical axis windmills (Score:1, Interesting)
Re:I think Slashdot is being had (Score:2, Interesting)
One way to tell that it's pseudo-science is that they claim that it's way more cost-effective than conventional energy sources. If that were really the case, it would merit a front page New York Times article. They also don't mention how they arrive at the 2.5c/kWh figure -- for turbines, isn't that a factor of how long the thing lasts, and maintenance costs, not to mention initial purchase price? I'm sure if I gave it a lifetime of 200 years, the cost/kWh would be virtually free.
Re:Could be useful for microgrids (Score:2, Interesting)
The design given in TFA is not the same as a Savonius Windmill. While I cannot speak to any improvements in efficiency, I will point out the differences.
The Savonius windmill uses a pair of buckets that allow air to pass from one bucket to another, while TFA's rotor does not. TFA's rotor seems to use the idea that as air moves over the front surface it is pushing while as it moves over the back surface, it creates a lift effect like a wing. This does not appear to be the same process as the Savonius Windmill referenced here [picoturbine.com].
The other main difference is the addition of extra stators to guide the wind into the system. I get the impression that, like the ducting in a ducted fan assembly, they help to cancel efficiency-stealing wind vortices and help to guide the air in the most optimal manner.
So, while I cannot say whether or not TFA's turbine is more efficient, I can say that it is most certainly not a Savonious windmill.
Time to put away the sock puppet Timmy... (Score:2, Interesting)
No doubt... (Score:2, Interesting)
Sterling D. Allan's personal website [sterlingdallan.com]. Check out some of the other websites he has founded and administers. Not to say that real scientists can't be religious or spiritual, but... come on... Given that the articles submitted here by Mr. Allan are more pseudo-science than anything, coupled with that list of websites, there's absolutely no reason this stuff should be on Slashdot, let alone the front page. Yeesh...
What's more dangerous, Slashdot; anti-science or pseudo-science?
LNG worst case. (Score:3, Interesting)
Actually, the absolute worst-case scenario is a BLEVE, [blazetech.com] which you Do Not Want. When all of the factors are right, heat from a really big fire boils the LNG in its tank, overwhelming the pressure-relief valve. The valve sends up a shrieking tower of flame as it fails to keep up with the rising pressure, and everything that I've read suggests that you shouldn't stop running while you can still hear it, because what happens next is ugly. The tank ruptures, sending shrapnel flying, and the pressurized gas explodes out, only to discover that it now has an opportunity to catch fire as it's already exploding.
This sort of "meta-explosion" doesn't happen every time some fire gets near a gas tank, of course: it's only the worst case.
That aside, it seems that about once every year or two a house somewhere in North America suffers from a natural gas leak in the basement and subsequent explosion that demolishes the house in question and badly damages the neighbouring dwellings. I've never seen an "enviro-nut" bring that up, though.
Re:More modern turbines (almost) don't kill birds (Score:3, Interesting)
Only to whiny people.
I love the huge turbines. I can see a medium sized wind farm from my home. They're beautiful to me because they represent pure, clean power. Not to mention, they're quite graceful in their movements and fun to watch.
The whiners who oppose them have their heads up their collective rear ends. Ask these people how they prefer to get their electricity and they can't answer you. Wind is ugly and kills birds. Solar is ugly and full of nasty chemicals. Coal is bad. Nuclear is scary. Tidal hurts whales and hydroelectric kills fish. Yet none of these whiners are willing to turn off their electricity and go back to oil lamps.
You can't have it both ways, folks. I believe an intelligent person should see through the "big ugly propeller" and find the beauty in it's cleanliness. I certainly do.
Only somewhat (Score:3, Interesting)
Your points are true only on a small scale, they fail on anything large.
All windmills slow the wind. If you add a second windmill, and the wind is blowing such that it would go from one to the next (in absence of any windmills/trees/buildings), the second windmill will see slower wind than the first, and thus generate less power.
All windmills create turbulence zones around them, mostly downwind. This too decreases the efficiency of the windmills downwind.
The only solutions to these problems is to space your windmills farther apart, or live with reduced efficiency.
As an aside, the above effects are why normal windmills have 3 blades, and not many - after every blade passes they need to wait for the slow wind to get out of the way to generate maximum power. (1 or 2 blade windmills would be better yet, but there are other technical details that make them less impractical in the real world) I suspect that you would get more power from your homebuilt generators if you got rid of a few of your blades - but of course you would need to experiment to see.
The last problem with scaling is you cannot just go up forever. There are substantial differences in windspeed and direction with altitude. Direction is mostly something airplanes worry about (and it doesn't matter to vertical axis turbines anyway). Speed is a different matter - wind near the ground is always slower than wind farther up. So if your turbine is tall enough, say 30 meters and near the ground, you lose energy because the wind higher up is acting as a fan to push the wind lower down. You can move the whole system up, but then you lose the advantage of the generators being near ground.
Simplicity is great, except that simple stuff may to be reliable. If you like tinkering with your windturbines as a hobby, this is not a problem. If you just want to use lights and such without worrying about the generation wind is not for you. The utilities can pay for complex solutions that are engineered to be reliable. They also have the ability to deal with unexpected problems. If one of your turbines breaks you are down to half power (assuming your solar input is negligible, you didn't specify so I don't know what it is), to the power company that is less than 1%.