New type of VAWT
 

I recently read about a new type of Vertical Axis Wind Turbine built in eastern Poland. It is 3 towers, 29 meters each, which produce 0.5 MW of power.
http://ecorenovator.org/forum/attach...1&d=1415566338

At first glance I thought: "Well, it's just a few VAWT drums stacked on each other. Building 3 next to each other makes it more stable."
But then I did more research and found that each 'drum' is really just a housing with the actual VAWT inside. The vanes are sized and positioned in such a way as to direct wind only to one side of the rotor while deflecting it from the other. This not only increases the efficiency (I found a source which stated 50% more efficient), but reduces noise to no more than 30-40 dB.

Among the other features of this design:

• Modular design, easy to size a project depending on local conditions and available finansing, easy to transport and install,
• Much safer for birds, takes up less space,
• No vibrations or infrasounds,
• Starting speed of only 0.7 m/s (compared to 2-3.5 m/s for HAWT),
• Nominal power at 6-7 m/s (other designs - 8-12 m/s),
• Built to not only withstand, but to keep producing power at wind speeds up to 55 m/s (other designs drop off above 12-15 m/s for safety reasons)

One of the things I could not find is whether each 'drum' produces power independently (taking advantage of varying wind speeds at different heights), or if all of the rotors in each tower are connected to each other, with the generator in the base. Nor could I find apicture of the shape of the internal rotor.

From a DIY POV, this can make small scale VAWT just as efficient as HAWT, and maybe easier to construct than specially shaped HAWT blades.

The low starting speed is very attractive, as is the low noise. I assume the efficiency is still lower than HAWTs. Any idea how much?

I imagine they're a little safer in the 'less potential for the blades to shatter off the hub impaling a neighbor' sense. and with the housing doing some conditioning of the air flow might be decently suited for more urban uses.

I just came across this thread, interesting concept. I like VAWTs but they just don't put out the power of HAWTs. The upside is they last longer, don't require the furling mechanisms, are better in shear winds and are easier to build for the amateur. I might give this configuration a try.
Rob

There just isn't the available energy in the low speed turbulent winds that close to the ground unless it is installed on a flat smooth terrain with nothing else for hundreds of yards in every direction.

Jim,
I think this is the main problem with wind all around. You need to get it up pretty high to get any real benefit. I've had emails back and forth with Ian from Homepower magazine about this. Every time they have a wind issue they show some guy hanging off a tower 80 or 100 feet up. The logistics to get a 300 lb wind mill up that high are ridiculous. Remember it's not just getting it up, there's the yearly maintenance. They're not PV arrays where you can just park them and walk away. How many people are equipped to do that?
I kept telling Ian that he wasn't doing any justice to wind by showing those pics without telling readers what's behind that work. I noticed he changed his tune in the last wind issue. to his credit he explained the immense difficulty of wind. It looks easy but is a tough thing to do right. I'll play with it now that I have my PV systems in but I'm not thinking I will gain a lot. If I can get a few hundred watts at night when the PVs are down I'll consider myself lucky. Those going to alternatives shouldn't even think of wind until they have PV in unless they live on the top of Mt. Washington in NH!

Rob

I'm a trained and certified site assessor for small wind systems and I usually recommend a tower at least 120 feet tall, and seldom find a site in western Wisconsin that is actually windy enough to justify the expense of a wind turbine, especially in recent years with the falling price of PVs. My personal wind turbine needs annual inspection and grease at the tower top--and it was hard work putting 500 pounds of machine on top of a tower. It made sense 35 plus years ago when we first installed it to power an off-grid home, but back them PVs were very expensive.

The real problem with any and all VAWTs is that they are never installed high enough to get powerful winds. People that favor vertical machines don't understand how wind works. A turbine of any kind on a short tower is like putting your water wheel or water turbine at the shore in the shallows because it is easier to get to .

Jim,
That's right, not only do mills need to be up high but now they're competing with PV's that have dropped drastically in the last couple of years. I just changed out a panel I hit with my backhoe. The original panel costs several hundred bucks a couple of years ago.... the replacement costs me $152.00. OK, that's wholesale but still, how do you beat that? The only thing wind has going for it in my view is that it compliments my PV.

I've been monitoring my site for several years so I know wind will work here, also I have a several acre front field, you need real estate for wind. That's another thing people forget. Also I can fabricate the complete windmill here which saves me quite a bit of money so any power I get is pretty much free aside from my building time. (I've got all the materials).

The only thing I need to decide is whether to put up the mill or do my microhydro first.

Rob