Most Important Questions to Ask About Wind Turbines

[Tim Smith]

I write a weekly article on my blog about alternative energy. This week my article is about the most important questions to ask when you're considering investing in a wind turbine. Any suggestions, as to questions, would be much appreciated and sources acknowledged. Thanks yet again, Tim Smith

[Rob Beckers]

I suppose you would like it to be an 'upbeat' article, so my points may not combine well with that. In general, I would point out the usual (but usually overlooked, especially by those eager to get a turbine running) points:


If you want reliability, get solar PV. Wind turbines have moving parts and operate in a harsh environment. The reality is that they break. Sometimes a lot. Even the good ones do at times, and they all require maintenance.
You need wind. While this is obvious it never ceases to amaze me how many wind turbines are put up in places that just don't have much wind. A good place for a wind turbine is actually not a place most people would want to live; it's going to be very, very windy. Consult the wind atlas (there are US and Canadian versions) before getting serious.
The turbine needs to be placed in the wind. People continue to put turbines on short towers, in places that are in the wind 'shadow' of trees, houses etc. People also somehow seem to think that the smaller the turbine, the smaller the tower. Unfortunately it doesn't work that way. To produce serious energy, a turbine needs a serious tower. People underestimate just how tall (and expensive!) those towers get. See the wind turbine site selection page (http://www.solacity.com/SiteSelection.htm) I wrote. Keep in mind that the guidelines on that page are minimum requirements!!
Wind turbines require maintenance. This goes to the first point: It is not realistic to expect to install a wind turbine and have it work flawlessly for 20 years. Even the best ones will occasionally break, and they all require maintenance.
If you want kinetic art, get a vertical axis wind turbine, if you want energy, get a horizontal axis turbine. Despite the current love affair with VAWTs, most are entirely unproven, and the ones that have been tested proved disappointing. Inherently a VAWT can only use half its frontal area to produce energy, putting them at a disadvantage in terms of materials used vs. energy output.
Pick one: Cheap or good. At this time, the cheap (Chinese made) wind turbines have very little to offer in reliability. If you want a more reliable turbine it's going to cost money. Even if you spent serious money, expect downtime for repairs or maintenance.


Tim, please post your article here as well. I would be interested.

-RoB-

[Tim Smith]

Rob,
An 'upbeat' article is good but my readers appreciate a "bottom line" truth article even better.

Thank you for your input. Your background makes your insights even more valuable to me. Several of my readers have expressed an interest in practical experience and solutions. By myself, I'm a very limited resource on alternative energy, so I definitely welcome a credible and knowledgeable source of information with integrity, you.

Thanks again, I will post a shortened version of my article tomorrow, Tuesday, November 2.

All the best, Tim

[Tim Smith]

I want to preface this by saying thank you Rob, for inviting me to post this on your forum. I'm not an expert but I hope to learn from you and others on this forum.

4 Must Ask Questions When Considering a Wind Turbine!

I’ve been recently considering a wind turbine. Since my backyard(playground) is relatively small and I’m restricted to a building elevation of 10 meters(33 feet), I thought my option was limited to a Vertical Axis Wind Turbine(VAWT).
I thought it would make a good learning tool for myself, the Mrs., kids and grandkids as well as produce a little electricity. I must say, that “produce a little electricity” has come back to haunt me.

The first thing I did, after attending Wind Power 2010 in Dallas, TX, this year was to start some research. After looking at some wind speed maps, I determined, rather quickly, I wasn’t in a “windy” location. I do have a backyard weather monitor station that measures wind speed. When my wind speed showed an average of 3.2 mph at ground elevation over a 6 month period, I had an inkling that might be a bit low but I did have periods of sustained 8 mph wind and most of the literature I had on VAWTs indicated that they would generate electricity at that low of a speed. I had the space, I had the wind(I thought) and I just needed to ask a few more questions.

I joined 3 different forums, hoping to get some expert advise. Green Power Talk Forum, Energetic Forum and Solar Electric Power Discussion Forum. I received links to other forums but time has it’s way of limiting us. I did receive some very good information.

As I talked with Rob Beckers, administrator of Green Power Talk, Ben Colla, a junior member of Green Power Talk and Russ & Bill of Solar Electric Power Discussion, the following 4 questions popped out at me.

1) This question was most prevalent, Do I have enough wind? As Rob Beckers pointed out to me, I may have enough wind for my VAWT to provide “kinetic art” but not enough to be considered practical. I really do like seeing a wind turbine churning out electric power but I’m restricted on future construction altitude. The only wind turbine proven to be efficient, the Horizontal Axis Wind Turbine(HAWT) was out of the question. It needed mounting on a tower and I was limited by space and altitude considerations. I still persisted.

2) How much downtime would I face? If I’ve learned anything, moving parts require maintenance. A wind turbine faces some of the harshest elements, what does that tell you about maintenance. I have a little mechanical ability but I wanted to keep my feet on the ground, several wind turbines require climbing, as part of maintenance.
I’ve conceded, my home location is not ideal for a wind turbine. The following questions are mostly “academic” for me, personally, since I obviously don’t have enough wind but something to think about if you do.

3) What about efficiency? A quick lesson I learned is that the maximum efficiency any wind turbine could achieve is 59%. A look at Betz’s law and supporting works will show you why that is fact. A VAWT design has an even less. With my background in aerodynamics, I’m still intrigued to search for a way to exceed that limit but …..

4) Can you consistently rely on power created by wind? Obviously, the answer is no. Rob Beckers essentially said wind power generation can be somewhat profitable and efficient in the larger and more expensive applications but it appears, predominantly, to be more of a “complementary” alternative energy source in smaller applications. Bottom line, the winds change.

In select areas, it is a very good companion to using solar PV systems. Some like the sound and aesthetics, some don’t. I still like the idea of harnessing what is readily available to us, that doesn’t negatively affect our environment but good ol’ common sense tells me, I’m not one of the fortunate(or unfortunate, as the case may be) ones to have enough wind. I guess, I’ll just take my kids and grandkids to visit some of these “cool” sites.

I couldn't get the pics or links with "copy and paste", feel free to view them at my blogsite - http://www.altsolarandwind.com.

[Rob Beckers]

Thanks Tim! Good article.
There's one thing I'm reading between the lines, that seems to be a general misconception regarding VAWTs: The physics generating energy from wind are exactly the same for a VAWT as they are for a HAWT, and there's nothing in there that would give a VAWT an advantage close to the ground. Despite the marketing talk, to make energy with a VAWT it needs to be at just as high a tower as a HAWT. Put it on a low tower, and it will do just as poorly as a HAWT would.

Talking about marketing, please realize that exaggeration is the order of the day when it comes to small wind turbines. If you believe the brochures, some will even beat Betz! Most are more subtle, and will simply claim energy production numbers that are well beyond the truth. It's a sad state of affairs...

You are actually in the same situation as me, in that zoning only allows for a 10 meter height. That means you should just give up on the idea of generating real energy with a wind turbine. It's not going to happen. But, that doesn't mean you can't have fun with it. When I have some spare time (unfortunately a rare commodity for me these days) I am hoping to build something, either HAWT or VAWT. The OtherPower forum shows the way, as does this forum. A simple Savonius type VAWT can be made with very modest means, it would look good, they are quiet, and it would still convey the message that you care about renewable energy. Of course, you should tell people that are interested it's really more about moving art, before they spent lots of money to have something installed that won't do squat to their electrical bill. If you don't have the site for a wind turbine, go solar! That's what I've done over here, with 6.4 kW of PV on the roof (admittedly, it helps that they pay 80 cents per kWh for PV electricity in Ontario).

-RoB-

-RoB-

[Milan Slovak]

Hello,

I live on the west cost of Florida.
The water in my back yard.

I would not put up any solar panel installations in my Hurricane prone location.
They would have to be Engineered to stay in place for the 140 MPH winds.
They would also have to be rated for impact with all the debris and clay tile that would hit them.
Then I would have to replace them!

Your must include, or take into account, more specific location information when choosing your system.

My location has wind everyday off the water.
A wind turbine out on a dock piling would be a good location with a pivot axle for servicing.

[Ralph Day]

Think of the engineering to hold a wind turbine in 140mph winds! Easier to anchor PV I'd think.

Ralph

[Rob Beckers]

As it happens, yesterday I was reading through Suntech's specs for their PV modules (they're likely the same for other brands). What struck me is how tough those things are! They are rated for wind speeds of 60 m/s, that's 135 mph. They also get tested to withstand a steel ball of 227 gram (1/2 pound) dropping on the glass from 1 meter height (just over 3 feet). You're right that it's the flying debris that poses the biggest hazard. Then again, if things get so bad that PV modules get destroyed your house is probably faring no better, and at that time it's a job for your home owner's insurance.

The vast, vast majority of small wind turbines are not rated anywhere near 60 m/s. The few (rare) exceptions that I know are the Proven wind turbines, and the Eoltec Scirocco. Maybe there are others that claim it, but better make sure they are actually installed in places that see those wind speeds and survive it (I know the Provens and Sciroccos are)!

If you happen to live right on the coast and have a good annual average wind speed then a wind turbine may be worthwhile for you. If your location has a very high average wind speed I would actually put the turbine on a short tower on purpose, in violation of the common wind turbine site selection rules; this is about the only situation where you you can defend the use of a short tower, of 40 - 60 feet. It will cost you in energy production, but it will make it much more likely for the turbine to survive. For hurricane prone areas I'd make it a tower that can be tilted down for those events.

-RoB-

[Ben Colla]

The vast, vast majority of small wind turbines are not rated anywhere near 60 m/s. The few (rare) exceptions that I know are the Proven wind turbines, and the Eoltec Scirocco. Maybe there are others that claim it, but better make sure they are actually installed in places that see those wind speeds and survive it (I know the Provens and Sciroccos are)!

-RoB-
I'd be concerned, at that point, about the tower strength. I wouldn't trust any home made tower to be strong enough, now would I trust the chinese hydraulic monopole towers to withstand that sort of abuse. Even if the turbine can, cope, it's still being badly abused.

[Herve Oizon]

I m buying a wind generator from Tairui, and i look for information and help on the wind controller use , version 240V , with output 20 battery 12V in serial , this product not seem coming from Tairui , and i ve any information on this equipment ( only a small manual ) not very clear !:cheesy: