Actual vs. rated wind power

That's interesting stuff. I live in a high flat region of the midwest US where they recently put in several new winds farms over the paost ten years. I hear there's more to come. Average annualized? i'd think the whole mess of them are way to new to calculate a return. As soon as you get close to getting an assesment they build more. I don't see what they're hurting. There's probably a down side, but i don't know.

30 miles to the South, there's a mile of coal cars that come form the Powder River Valley every ten minutes. Continuously. Makes me wonder for how long?

Given a 20% annualized return, I suspect the coal cars are safe for a long time. Anyway, the coal is probably shipped to China where they consume it without pollution concerns.

Hi WindGenMan,

I beg to differ!

Here in the UK it has been found that wind power is not as effective as first thought! The problem being that during the winter months we have weeks of still air, and this is in the period when we need the most power to heat homes and cook our food. During the last three weeks here in the central part of England where I live, there has not been enough wind to turn a single wind generator, and as the cost of constructing and placing these things is enormous we are loosing out!!!

Here in the UK we are commited to producing power by renewables by 50% within 2020, and because of this we are looking at other ways than wind turbines to produce power! These include wave, tide and barrages accross two of our largest rivers. One of these barrages was first thought of in 1976, it is the Severn Barrage spanning accross a river mouth that is 21 miles wide! This could produce enough power to power 5 large cities, they main problem there has been the ecological destruction of important bird sites. But now this barrage has got the go-ahead.

Don't get me wrong, wind power has it's place, but it is very unreliable at the best of times.

Spencer.

PS. These days here in the UK they have had to increase the amount of trains as more and more commuters have abondond their cars, including me!

Thanks rutleddc, I agree. My purpose in opening this thread was just to pass along some comments I had heard at a green energy conference and to start a discussion. Politicians come and go, but with fossil fuels, it's all go. We engineers have a duty to think and discuss rationally (which engineers should be able to do) all of our options. Allowing politics to come into the discussion is non-productive and futile.

As I get older I tend to think more and more like my father who hasn't voted in years, because he doesn't want to encourage the bastards.

Thank you!

milo

you are off topic and full of political nonsense. Please get a log in and present facts to back up your immoral attitude.

Great demonstration of Seeing both connotation and denotation of the original question!

milo

I find it hard to believe that anyone savvy enough to fund and construct a wind farm would do so without checking the local conditions. I learned a rule of thumb some 20 years ago, that an average daily wind speed of 14 mph would be sufficient to make wind power generation economical. With the rising cost of more traditional (well, it's a recent tradition) fuels, that may be even lower today. If there's no meteorological data (hard to believe) for a given location, all one needs is an anemometer and a year to spare to find out if your wind farm location choice is a useful one...

Once they have collected the tax credit - do they really need any wind?

I would like to start by saying that when choosing a wind turbine, one must look at the manufacturer's power curve. This curve will show the amount of power that can be produced at certain wind speeds. (check out the bottom of this file for the GE power curve for this model. You will notice that for this particular model the rated power is at a wind speed of 14 m/s. If you want to see the problem, check out this wind map...it's canadian so use your imagination if you aren't one of us. Notice how there is barely any (or no) 14 m/s wind? Where are we to achieve this awesome 3.6 MW of rated power?

I believe this site operates on an average wind speed which would mean, to me, that the average wind speed in my area is 6 m/s (at 80 m high) consistently throughout the year. This is actually a half decent speed; at least it would seem it is since there are 300 or so 1.5 MW turbines cropping up in South-Western Ontario. But, for the wind turbine mentioned above (that probably cost almost 3 million $) only 400 kW would be produced on average...or 3.5 GWh throughout the year. When I look at wind turbines, I always look to see how much power can be produced in my area...especially since these things will rarely if ever reach their rated power output. Of course this isn't 100% right since there is some variability. The turbine could be getting 3.6 MW during the apex of a storm and it could get 0 during the calm after the storm

Also, air is denser when cold and produces more energy per m2 of span...which is why wind power is favoured up in the chilly north or just in winter in general. Solar panels are better in the summer since there is more sunlight but lose some of their output in the winter since the sun is further away. <-- note that I don't have quotes to prove this, but these are things my professors have said in class...

Hope I helped someone, somewhere!

Achilles

FLASH - i just heard a new one today:

There's a guy that wants to fly (like a kite) a multi-prop turbine up to 15000 feet where there's a contant wind. Piping the energy down an umbilicle cable/teather.

Sounds like a good idea to me.

If the percieved problem is that the wind is not constant, flying turbines aloft, up to constant wind currents could overcome this.

It's possible that i didn't complete my thought/comment with the last post.

My understanding of the original comment by "thermo" is that it is in reference to utility scale wind farms. Wind farms are always located in areas in which the average wind speed at hub height are sufficient to drive the turbines at or near their rated capacity the majority of the time. In fact, governing systems on newer turbines are largely used to regulate rotor RPM, because blade designs are remarkably efficient in harvesting energy from the wind. Generator over-speed is more of a challenge in newer machines than is insufficient power output.

But, don't just rely on my--or anyone else's--input in this forum for your information. Start with http://www.nrel.gov/learning.html. Then visit your local wind farm, if you have one, or visit one on the internet.

Again, the best evidence of wind generator technology efficiency is in the economics. The U.S. is a nation where ROI drives investment behavior far more than good intentions. Wind turbines have an excellent payback period, much better than other energy sources available at this time, and there are still very large areas of untapped wind resources around the world. The probability of meeting the most ambitious of renewable energy portfolios standards is extremely high. Unfortunately, as evidenced by the content of this particular forum, ignorance is the by far the biggest obstacle to reducing our dependency on costly, non-renewable energy sources.

WindGenMan

Thank you "windgenman" for taking the time to enlighten us "ignorant" and unwashed engineers. It is truly unfortunate that, when one who has possession of relevant knowledge and is asked to share it in a forum such as this, that said person adopts a superior attitude and makes such condescending comments. We all recognize your demonstrated authority in all wind-related matters, but just because we wish to reach your Himalyan heights of knowledge is no reason to call us "ignorant". I've always thought that the purpose of this forum is to encourage dissemination of knowledge without bias and thereby, furthering the cause of engineering as a whole.

Sorry. Not my intention. I am still learning how to respond within this venue without becoming defensive. I deal with a lot of public misinformation about wind in my line of work, which I find very frustrating. I live in California where the grid is pushed to its limit on a daily basis and there has been no new construction of power generation facilities in over 15 years. Many proposed wind farm developments are on hold because of the spread of false information. In the meantime more rolling blackouts are likely.

Thank you for calling me on my arrogance.

WindGenMan

Don't know if any of my info was wrong, but if it was, I wouldn't mind knowing what I was wrong about (especially since what I wrote was more based on what ive learned over the last 2 years, not just regurgitated oil-crapsense).

Amen, especially since mine was (mostly) learned 10 times longer ago than yours. I saw no direct refutation or update to my stated figure of 14 mph sustained wind being the typical minimum for efficient, effective power generation. If that HAS changed due to improved technology, I'd like to know about it rather than remain ignorant and spout gibberish...

Professionalism please gentlemen. All power generation plants have a nominal power generating capacity called the name plate or rated capacity. All produce less than their rated capacity in real terms due to maintenance and other issues. The degree of underutilization of wind systems is generally greater than that of fuel based systems but this is naturally figured into their cost justifications.

The type of wind turbine also has an effect. Variable pitch prop systems generally have higher efficiencies relative to their rated capacity than non-variable systems, but they are somewhat less efficient at capturing total wind energy available. The real advantage they have is making power that suits the grid.

The very important and somewhat disappointing factor in the cost effectiveness of wind power is the durability, serviceability, and longevity of wind turbines. These are engineering issues that can be with persistence improved. Ignoring the fact that wind turbines only produce power when the wind blows is neither engineering sense nor political sense. I would rate it as non-sense.

As a result I and many others are working on new means.

Best regards,

Mr. Gee

What are these new means? You piqued my interest!

Less than 27% annualized would cause financial collapse