Paul Gipe has put together an interesting compendium of articles about VAWTs
“For whatever reason, many VAWT designers are prone to more hyperbole than most other wind turbine designers. Some claim their turbines will produce at less cost and with less impact on the environment than conventional wind turbines. Maybe such claims are due to widespread ignorance of VAWT technology or its long history.”
Paul examines the only major deployment of VAWT technology that actually really happened during all the years of hype.
“FloWind’s Darrieus turbines operated for about a decade generating millions of kilowatt-hours, and in doing so delivered respectable performance until fatigue and design weaknesses led to increasing unreliability and they were removed. FloWind’s turbines, when in regular service, delivered about the same performance as nearby conventional wind turbines relative to their swept area, but performed poorly in comparison to their inflated power ratings. “
I have a cousin who is a mechanical engineer and who has done a lot of work on fluid dynamics, primarily with gas turbines. Years ago, he told me that he had doen a simulation of VATs and found that there was an incurable vibration that set up as a result of the blades passing behind the tower and behind the other blades. It is probably this vibration that eats away at metals until they fatigue, to the point of failure.
In the late ’70s and, later in the ’80s, Hydro Quebec installed some VATS that failed. Why flog a dead horse?
It’s pretty simple to understand the fatigue problem. Normal wind turbines have lift forces that push them downwind all the time: constant direction. VAWT blades take wind from one side and the other in every revolution: reversing forces. Hold something and waggle it hard and you have a good chance of breaking it. Slender VAWT blades usually break. This is one of the fundamental problems of the VAWT. It can perhaps be solved (at a cost) but my question is why solve it, when you can use a HAWT that is superior in pretty much every way?
the advantage of vawt is lower noise but not so stable in high wind.while hawt can change the blades known as pitch control.
I note that Mike Reynolds (of “Garbage Warrior” fame, the developer of the Earthship house built from earth-filled tyres etc) is fond of VAWT – he feels they are robust, require little maintenance, and have proved themselves with his Taos, New Mexico settlement. ?is he wrong? I personally like the look of the VAWT designs, and as a supplemental energy source (to solar) the idea of a lower maintenance wind turbine is appealing versus the propellor-type turbines.
hi Bill,
I have two questions about that. First is whether there is any record of how much energy the garbage warrior’s turbines actually produced? Second is why is it that the wind turbines with all of these supposed advantages have not become a runaway success and completely replaced the horizontal axis type? People say stuff about vertical axis wind turbines but the proof is in the total lack of market success of the genre.
Vertical axis turbines have been around for decades and all of that time they have been touted as new and better. In fact to be accurate they have been around for hundreds of years longer than the horizontal ones that have long ago replaced them due to superior efficiency and reliability. It’s only me that has been around for decades hearing about them and wondering what the fuss was.
My wife and I visited Taos and rented an Earthship for a week. Having built a turbine from Hughs recipe book, I was also very interested in seeing their dynasphere. A clip of it can be found at:
https://www.youtube.com/watch?v=g4ONahJ5cAQ
During the week that we were there it was not working, I did not get any information as to why. In the video a person points out that the dynasphere is turning while a nearby HAWT is not spinning at all. You can clearly see that the generator is not attached to the dynasphere, so it is not under any load, and the HAWT could very well have the brake applied. I’m with Hugh, I like the idea but not the product. In my eyes it’s hard to beat a well designed and robust HAWT, placed in a good location.
thanks, George => so you didnt see any evidence that the VAWT was achieving anything useful when you visited Taos?
thanks for the feedback. I am keen to tinker with a home wind generator this year, and the VAWT looked to be quieter and perhaps less likely to trouble birds etc as it just looks less likely to chop things up (certainly the “dynasphere” model looks pretty). I think that there needs to be more than raw energy efficiency in the choice. Is it then not true that such a design would need less maintenance / be less fragile than a HAWT?
hi Bill,
There are two types of VAWT: low speed and high speed. Low speed VAWTs are quiet and durable. Their efficiency is dismal. They need very heavy, low speed alternators. They are usually of the savonius type. http://www.windside.com/gallery
More often people are referring to the high speed or Darrieus type of VAWT which has more slender blades. These can achieve acceptable efficiency and the rpm is better too. The problems they have include fatigue failures of the blades, problems with starting, problems with controlling the speed (governing) and difficulties with mounting on a tall enough tower to catch wind.
Tinkering with small wind turbines is fun but can be frustrating. It’s not an easy path. I have been doing it since the 1970s. Don’t make like difficult for yourself from the start by trying VAWTs. My HAWT designs are quiet, efficient, and as easy to build as I can make them. I have noticed that many people start out as VAWT enthusiasts. It’s a blind alley.
best
Hugh
thank you for taking the time to reply! I will start looking into HAWTs as of now!
best wishes
Bill