georgeob1 wrote:Walter Hinteler wrote:Some A2K'ers stood recently in the middle of a bigger wind farm: the noise is really THERE = close to a turbine.
I can believe that, although I don't have much direct experienced up close with them. I do have some experience with propeller and turbine noise, and know that the propeller on a small aircraft engine turning at 2,500RPM can be heard miles away. The much larger rotors on the typical wind turbines should generate a good deal of low frequency noise. However their rotational speeds are much less and a good deal of effort has gone into reducing the sound impact - though I don't know how effective that might be.
Well, it's a bit noisy just below of them ... but -what I think- not an "unpleasant" sound. A few meters aside, you hear less to nothing.
Was there much low frequency noise? It is less rapidly attenuated in the air and can travel far. I suspect that, at least from a theoretical perspective, it is the defining problem.
I would describe it as low frequency - with a typical sound when a rotor blade passes the tower ... like ssssst .... sssssst[/I .... :wink:
I have been to several huge wind farms frequently (because I passed them, alone or with vistor, and was looking for photo motifs).
You don't notice the noise when you aren't rather close to the towers.
In this example, I heard the one behind me, but none of those in front
[img]http://i10.tinypic.com/6fkcfev.jpg[/img]
That's pretty good. Those in the photo look like 500KW machines. Only 2,400 of them are required to equal a standard power plant.
These are newer turbines, 1.5 to 1.8 MW.
(Those 500KW were built until 12, 15 years ago.)
On these hills, in our county (6 km breadthways, stretching over 45 km) we got now nearly 200 out of the overall 254 wind turbines.
Walter Hinteler wrote:You don't notice the noise when you aren't rather close to the towers.
In this example, I heard the one behind me, but none of those in front
There's one just behind where I park my car when I attend a particular group of events. Every year, I think it's not operating when I get out of the car - til I turn and actually look at it. Not dead silent, but it fades into the background of regular parking lot sounds.
In today's NYTimes, William Grimes describes the book, Cape Wind - about a bruhaha on wind turbines/Cape Cod.
http://www.nytimes.com/2007/05/25/books/25book.htm
The more I hear, like ehBeth's experience, and Walter's, the more I don't get the resistance, especially with the higher KW, or MW.
That article about the troubled folks near the wind turbines in England mentioned this thudding going on, and vibrations.
Well, I guess it seems simple to me, if that were so, don't put them right near homes. But then, ehBeth and Walter, and that reporter on the English story, didn't hear/feel the effects that the nearby residents reported.
I haven't read the book Osso but this quote from the review"
"It offers the delicious spectacle of self-described environmentalists, infatuated with the idea of alternative energy, tying themselves into knots trying to explain why a wind farm would be a splendid idea anywhere but in Nantucket Sound."
Seems to sum up the situation with Cape Wind pretty well. The last I had heard one of the groups fighting the Cape Wind project had suggested that moving the project to the hills of Western MA would be a splendid idea - presumably, people in that part of the state wouldn't have the political power to fight it.
I spent about 120 hours researching objections to wind power for a job a couple of years ago. Mainly looked into bird/bat kills and noise complaints.
The preponderance of evidence regarding bird and bat kills was that, in general, it is of minimal concern if considered in light of reduced carbon (and sulfur and mercury and whatnot) emissions that we get generate here in the US midwest with our smaller, older coal-fired plants. Altamont pass (near San Francisco) did seem to be an issue for raptors, and even there raptor mortality dropped significantly after some of the turbines were relocated. Locally, there was still a great deal about siting of a windfarm within two miles of Horicon Marsh, which is a major stopping point for a number of low-flying migratory North American birds. (In fact, one of the reasons I left this job was because my boss was unwilling to acknowledge concerns unique to the marsh in the web site we were developing, and was tacitly instructing me to ignore any evidence that it might be problematic. I abandoned the job and the pages never got finished.)
Something I found interesting was that television and some cell-phone towers have been implicated in mass kills of tens of thousands of migrating birds at a time. It didn't appear to be the towers themselves that did the birds in -- these are big and clunky and very visible -- but the guywires needed to stabilize the towers. But I didn't read anything about objections to TV or cell towers on the basis of risks to wildlife. Bats, too, have been killed in large numbers by broadcast towers.
The noise issue is considerably more contentious. Noise is a very difficult thing to quantify, especially as the quality of a noise is a major determinant in whether or not it's objectionable. Of course the manufacturers of turbines and the folks who benefit from putting them up claim that it's not an issue, and they site decibel measurements to back this up, but there are many, many anecdotal accounts of the maddening character of the noise that has nothing to do with how loud it is, but rather with how regular, rhythmic, and visceral it is. I can appreciate this -- the regular rattle of a rusted-out old car with big subwoofers in the back a couple of blocks away drives me nuts, even if it's not very loud.
Another odd phenomenon I ran across was the notion of shadow flicker -- that early or late in the day houses in the long shadow of a turbine have sunlight flicker as the blades pass in front of the sun, and some people report that the effect can be very, very aggravating. I only found a few reports of this, though, and it may be that the odds of this occuring are pretty low. At any rate, at higher latitudes it's unlikely that a house would be in the shadow of a turbine for more than a couple of weeks a couple of times a year.
I don't have any references for any of this any more -- I left it all at the job. At any rate, it did seem that no nation could expect to have a stable electrical supply if more than about 10% of its electricity is supplied by wind power (about where Denmark was at the time I was doing the research, I think), so it's hard to believe that wind ever could be feasible as a major source of energy in a country with an expectation of constant, abundant electricity...
That flicker business was mentioned in the article about the English town with turbine problems.
patiodog wrote: At any rate, it did seem that no nation could expect to have a stable electrical supply if more than about 10% of its electricity is supplied by wind power (about where Denmark was at the time I was doing the research, I think), so it's hard to believe that wind ever could be feasible as a major source of energy in a country with an expectation of constant, abundant electricity...
This seems to have changed:
Denmark now has about 20% - in the East-Frisian region of Germany it is actually 74% of all electricity as in some regions of Denmark.
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The German friends of earth (BUND) found out that about 0.5 birds per windturbine per year are killed.
I think we are in a time when we will have to find multiple sources of energy. Wind energy is certainly part of the solution.
