What VAWT has the best output for low wind conditions

[Tim Smith]

I'm new to this and hope this is the correct or accepted way of entering this forum. I recently attended the Wind Expo 2010 in Dallas. I saw some tremendous VAWT and HAWT examples.

My local regulations severely limit altitude at which a wind turbine can be erected, so it was an easy opt for VAWTs. I'm leaning toward a unit mfg. and marketed by Urban Green Energy, called Eddy. I would appreciate any input or suggestions from any of you out there. Thank you in advance. Tim

[Ben Colla]

How high can you go?
If you can't get above 30 feet (10 meters) stop right now.
If you live in an urban area, you probably can't go high enough.
What is your average wind speed?

Read http://www.greenpowertalk.org/showthread.php?t=12908

[Tim Smith]

Hi Ben,
Thanks for the reply.
I'm located in a small airport's traffic pattern and restricted to a limit of 10 meters elevation for new construction. At my house, the average wind speed is around 3.2 mph, measured by my home weather station and averaged over a 6 month period. Some seasons are a lot gustier, up to 55 mph gusts(not sustained) but from what I understand, gusty type wind is not preferred and the closer to the ground, that is what predominates. I like VAWTs, aesthetically, but have little experience around them. Tim

[Ben Colla]

10 meters = 33 feet (or so) This is the bare minimum of height for a tower. And you should really look at 15 meters, and preferrably 20 meters. But you can't do that. You can't exceed 10 meters.

3.2 mph is 1.5 m/s which is so low it's just not funny. Check http://www.otherpower.com/bottom_line.shtml and look at the chart. Pick 4 mph and see how much power there is. Basically, none. Really there isn't any power in Wind until you get to about 8 mph (3.5 m/s)

To get any useful power (at your wind speed) you'd need a 20' diameter HAWT, probably on a 60 to 100 foot tower (30 to 45 meters) Even then, you'll only get enough to power a light bulb, most of the time. A few hours of high speed (55 mph) won't get you anywhere. refer back to that chart and look at the highest wind speed colum, at a diamtere you can achieve, which is probably 10 feet. you can get maybe 2000w, for say 3 hours 6 times a year. 2kw * 18 hours = 36 kWh from your high speed periods. But, (and this is the killer) with these high speed wind events, you'd want to shut down your turbine so it survives.

VAWTs are even less efficient, than the preceeding paragraph assumes.



Forget wind, you just don't have the wind speed and you can't get altitude to try and resolve this. Look at solar panels for electricity, and some form of panel heating to eekp warm in Winter.

[Tim Smith]

Ben,
I'm glad to have the link and info, it appears to be predominantly for HAWTs. I'm glad to have some of the formulas to calculate how much power the wind is capable of producing.

I know one of the reasons HAWTs are rated to be higher efficiency. The entire blade faces the wind during it's entire rotation. With the "modified eggbeater" design of some VAWTs, there blade efficiency is rated nearly equal to HAWTs. I do have the equivalent of 3 months out of the year when actual, steady wind speeds average just over 8 mph.

My home is south facing, with only two openings toward the front. It is well insulated and incorporates the Pell window system - double paned with argon in between. Our electric bill averages $80 monthly through the winter months.

I'm not worried about the return investment in $$$ at this point but being able to even produce any electrical energy without assistance from the "grid"(money hungry utility companies)and provide an example to my kids and grandkids, is my motivation.

I, naturally, want to get the most bang for my buck and solar PV panels is in the mix for me, I would just like, an even somewhat effective, wind turbine.

Are there any direct links to sources that have any information on VAWTs, that you know of.

Thanks again.

[Ben Colla]

When I started looking into a turbine, I knew absolutely nothing on the subject. I was in fact mystified by the 'they are so open, why are they all only 3 bladed'. I found out about betz' law, and much more besides.

I found out that VAWTs, typically produce less power than HAWTs, so I didn't look any further than that. So, no I haven't bookmarked any links specifically on VAWTs.

[Rob Beckers]

Hi Tim,

I can't help you much with VAWT brands/types that are known to work well. Maybe they're still too new (at least as commercially available small wind turbines), maybe the ones that get to be well-known turn out to be disappointing (then again, so do most HAWT small turbines).

The inefficient types of vertical axis turbines you refer to are as a whole known as "Savonius" type turbines. They use scoops that are pushed by the wind, relying on drag to convert the wind's kinetic energy into mechanical energy. The more efficient type are known as "Darrieus" turbines. They use a regular airfoil, just like a HAWT, to convert the energy in the wind. Airfoils rely on lift to do that, not drag, making them much more efficient.

There is a fundamental downside to all vertical axis turbines that makes them less efficient than their HAWT counterparts: Half their frontal area that intercepts the airflow is always turning against the wind, adding negatively to the harvesting of energy. So, when looking at potential energy production you have to divide their area by two compared to a regular HAWT. That makes them large compared to a HAWT that produces a similar amount of energy for a given location.

The advantages of VAWTs are listed as being not directional; they can work with wind coming from any direction, and not requiring a high tower. That first one is true to a point: Yes, a VAWT will work with wind coming from any direction. They will not do any better with turbulent air than a HAWT though, those blades still need to see airflow at the proper angle, and swirly turbulence does not provide that. They won't do very well on short towers either, and for the same reasons as HAWTs: Wind turbines need to have 'fuel' to work, and their fuel is strong, laminar airflow. That can't be found close to the ground, it's like putting your solar panels under a tree, in the shade.

Now, I actually like VAWTs a lot from an aesthetics point of view. They look great! I'm not being sarcastic, I really believe they are a work of beauty to look at. There's nothing wrong with putting one in your front yard, as long as you realize that it's more about kinetic art than energy production. Don't expect too much.

-RoB-

[Brian McGowan]

I got one of these to put up for a test. I promise you will probably not get what they claim you will as far as power goes.
http://www.hydrogenappliances.com/Hornet1000.html
It is on a 20' guyed tower in the worst possible conditions. It was about $330.00 on ebay. I made a gin pole to raise and lower it. I set up a dump load controller and everything. A complete miniature little system. I learned alot and it was a good test. It is about as simple as it gets. I call it the "sledgehammer" of turbines. Altogether it will cost a thousand dollars or less. If you find yourself making power then you can consider a bigger better unit and sell this one used on ebay and make some of your money back and use it towards a bigger setup. I have seen bigger price tags on weather stations. If you are not making power you will know and you can sell it used on ebay and make some of your money back and know you gave it a try and probably learned something. A class 3 windzone starts about 4 miles west of me. I am on a hill in a neighborhood and the tops of the trees are bent towards the east. I have had to run around looking for ways to use power a fair number of times because the dump load was running and I wanted to use the power in better ways. I get a little kick when I see it turning. It also spends weeks at a time (mostly during summer) doing nothing. I put mine up entirely with ground anchors (augar anchors) and I can probably get the whole thing down and removed from the ground in an hour or so all by myself. I did that so if anyone complained I could get it out of there in no time. So that's my 2 cents. It is a good test for cheap and you get to play with a windturbine and if it doesn't work out you haven't lost much. Next task is to convince the township to let me put it up on a taller tower. Height limit here is 35'. If I can't get above that I am done as much as I do not like it. There are several windturbines on nice towers in all the surrounding townships. This is amish country so there are also plenty of water pumping windmills. There is one Enertech turbine on a telephone pole about 2 miles from me but I have never seen it turn. I think it's a 13 footer and about 30 years old.

[Tim Smith]

Rob, thank you for the straight talk. Brian, thank you for the link, I can get up 20'. You both let me know that I have better options. Eddy is "out the door". I will check out eBay, practicality wins out.

[Jim Asprey]

Hi Tim;
check out the wind tamer on you tube.Hope this can help you.




jim

[Tim Smith]

Jim,
Thanks for the "heads up" on Wind Tamer Turbines. I looked at their videos on YouTube and then went to their website. The principal of the creation of an air vacuum structure for the purpose of increasing airflow, like a jet engine, is something that crossed my mind. Now to cut through the marketing hype to see the actual(in use) performance. I'm glad to see this, I will dig deeper and see if we can get Rob or one of the experts on this forum to weigh in. Tim

[Ben Colla]

It sounds good, but clearly is non viable, or adds to much cost via extra weight and stress on the yaw bearing. It also will probably add to the noise. I'm not an expert, but you have to ask yourself why there are no commerical wind turbines using this idea.

If you want a wind turbine that works, copy what the industry has done. They are a highly polished design now.

[Tim Smith]

Hey Ben,
Sticking with "polished" industry standards may be the best answer. While I was studying aerodynamics, one of the first lessons that really caught my attention was in the use of wind fairings and use of the "venturi" principal. Basically, when the "industry" started incorporating the use of radial engines on planes, they served their intended purpose but as time went, wind fairing were developed to increase the efficiency of the aerodynamic properties. It seems some of the methods used for aircraft efficiency might carry over. In aircraft, not only is very light weight required but also resiliency and strength. From dye penetrant testing to ultrasound non destructive testing, any weak areas can be determined and a better engineered design developed.

The wind energy industry does have the time tested proof for current designs and I don't have the personal funds to research new methods but new technology emerges everyday. We can probably dismiss a lot of it but I scarce say all.

I'm enjoying this discussion and learning from it.

[Glenn Kyllonen]

I am new to this forum but have been building turbines for a few years now off and on.

I too am in a low wind area much like Ben. I have the good fortune however to be on a hillside at the end of lake Okanagan. The wind comes up most days on a fairly regular basis so my efforts are not wasted.

Of the turbines I have seen on the web and then constructed in my shop I would have to say that the Helix Wind design works the best for low winds. It produces a lot of torque and self furls in high winds or at least my variation does.

It is silent, doesn't kill birds or bats and the people next door even like the look of it.
I have it mounted directly to the peak of my roof and it stands only slightly higher than my chimmney. It performs well with the turbulent winds we get in this area.

My only problem is with finding a low enough rpm generator. The Wind Blue one I have been using causes me to gear up the turbine and I have had several problems when running anything but direct drive.

If any one knows where I can find a very low rpm generator (say a cut in of around 30 rpm) I would be interested in purchasing it.

Cheers

[Tim Smith]

Hi Glenn,
I've been looking through the "For sale/wanted marketplace" section of the forum and there are a lot of interesting articles for sale. You might find what you're looking for, there. Good luck.

[Glenn Kyllonen]

Thanks for your feedback.

I found the Hurricane Mark 5 and it output 12 volts at just 40 RPM, this is exactly what I have been looking for.

I will post again once my order arrives and I get some real data.

Cheers

[Tim Smith]

Hey Glenn,
How tall of a pole are you going to mount your turbine? How high are you located on the hillside? Just curious because I'm restricted on any building elevation and have about decided that anything I put up will mainly be for aesthetic value and maybe a little educational, not for any significant power production. Looking forward to hearing about some of your results.

[Glenn Kyllonen]

Hi Tim, I do not use a pole at all. My turbine mounts directly to the peak of my roof in a special aluminum frame I designed for testing purposes. The top of it stands just 5 feet above the peak. It worked so well I just left it up there.

On another note though, I finall recieved my test equipment. a digital tachometer and a handheld anomometer. They both work great. I did some comparison tests using a 3 speed household fan and the scale model prototypes I have constructed and got some suprising results. My scale version 2 Blade helix style VAWT which blocks 153 sq. inches takes an 8mph wind to get spinning at all but my new 3 Bladed scaled down helix design based on sacred geometry with a blockable wind area of only 36 sq. inches starts up at just 3,9 mph.

I did some further calcs and the reason is in the surface area. My 2 Bladed has 261 sq. inches compared to my 3 bladed design which has a whopping 623 sq. inches and uses a tunneling fin design to speed up the air between blades.

I have yet to do high speed power tests but the new design will be able to mount without the frame which was quite expensive.

I will let you know how it turns out.

Cheers