There has been controversy (including heated some places) about the noise generated by windmills. I have never personally heard a noisy windmill, but so the story goes. (They make people barf their guts out all over a yard...they make cows deaf and keel over and fall dead... and similar horror stories. Whatever human mind can dream up. My mind is particularly creative, so I could horrify you all with my stories of windmill damage. One windmill deafened and then killed my entire family, it was so damn LOUD.

We should all favor wind as an energy source. Power goes up as the cube of velocity, so when the wind blows twice as fast...one can get eight times more power out. And of course wind is an infinite resource. And unlike fossils - which are having an increasingly destructive impact on this planet - drawing energy from wind does no harm to mother Earth. Some people get very upset about windmills killing birds...but fossil fuels are most assuredly killing way more birds...and causing many to go extinct. So opposition to windmills is really quite silly in that regard.

A possible solution to the noise issue comes from the world of nature. The wings of owls are exceedingly quiet; virtually silent; so they can pounce on a mouse without being heard coming. Evolution gave them the ability to fly very quietly.

So imagine that quite nifty natural technology - which makes an owl's wings virtually dead silent as they swoop through the air - applied to a windmill blades. In other words, put an artificial surface on the blades that's very similar to the feathers found on an owl's wings. Perhaps...even big windmills could be rendered almost silent, as well. Then the 'whoosh whoosh whoosh' would become...............

Barely audible. And one would expect the complaining to stop.
Ah but, Rod. If they made silent windmills we may have even more kamikaze birds, then what will people say?
Not to mention balloonists, skydivers etc. who wouldn't hear them either.
You're a clever guy, what's the answer?


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Why does Don Quixote keep coming to mind...? :lol:

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-DF
gwynnie wrote: even more kamikaze birds [and]
balloonists, skydivers


Second point first. Anyone who balloons or skydives without knowing what's in that general area - be it high-voltage towers, windmills, whatever - is kind of asking for it. Balloons do drift, of course. I would say...as a general rule of thumb...if someone decides to plunge to the earth from way up...or do the Hindenburg thing...or pull a Mary Poppins and fly by umbrella...it's not really a windmill's fault if someone gets shmoonched by it.

If a silent windmill killed a skydiver...I think the family's lawsuit would get tossed. If I was a lawyer defending the windmill owner and the complaint was: it was too quiet? I'd argue...what should a windmill do...keep broadcasting a loud message: DON'T HIT THIS? Besides...there are way too many people. :-)

Kamikaze birds... I don't know why they cause bird deaths, other than the obvious physics. I have no idea what the numbers are, but I doubt it's ever a big mound of birds at the base of those things. A few, maybe. I'd say it's probably the same issue as when birds hit buildings. They don't see them. As strange as that may sound. Skyscraper...who could fail to see one? But...boomp! Another bird that will never fly again. We don't say: no more skyscrapers, 'cause they kill birds, do we. No.

Kamikaze...good term for it. Some of them must be.

I'm certainly no expert on either issue, birds or windmills. But I doubt that very quiet windmills would cause any more bird deaths. Because...probably the principal reason they fail to keep on flying is they don't see the blade that hits them, or they hit. And...it may not necessarily be the case that sound up close is as many decibels as at a distance. I've never been near a big one, or studied the sound issue, so I don't know. But it seems to me possible that up close, the blades are actually quieter than at a distance. If so, making the blades quieter would presumably not affect the bird strikes stats much.

I would guess that in terms of bird deaths, sound is not the principal issue. It's visibility. That would certainly fit with birds hitting them, or getting hit, despite they make noise.

Likewise, kamikaze deer bound out onto roads, like they are entirely care-free. Presumably their eyes are locked on the other side of the road, their destination, which - but for BANG! - they would reach. Cars make noise. So one would think...not now; car coming. But they don't see it coming. I assume they are looking where they are bounding. I'm going over there. A deer doesn't think: I may not make it. That would require a certain level of mental sophistication which they seem to lack.

Probably birds are similar. Doh-de-doh, I'm flying happily along - looking mostly where I'm going - I don't care what that 'whoosh whoosh' is - I've never heard a hawk or eagle that sounds like that, so what me worry - and then suddenly something is right in front of them, so fast they can't swerve, or it just - boof - knocks them out of the air. I don't think windmills should get the blame for it. Any more than a passenger airliner's engine swallowing a seagull should be blamed for the seagull's demise. Probably not too many seagulls make it all the way through the engine. At least...not intact. Do we blame the engine, or the airline, or the pilot? No. We blame the seagull. Stupid bird shouldn't have been there.

I'm sure it would be possible to rig the blades so they were more visible to birds. Something like flashing lights on them. But there is no getting around the blades moving relatively fast, or the fact that birds will be birds.
Rod___ wrote: There has been controversy (including heated some places) about the noise generated by windmills. I have never personally heard a noisy windmill, but so the story goes. (They make people barf their guts out all over a yard...they make cows deaf and keel over and fall dead... and similar horror stories. Whatever human mind can dream up. My mind is particularly creative, so I could horrify you all with my stories of windmill damage. One windmill deafened and then killed my entire family, it was so damn LOUD.

We should all favor wind as an energy source. Power goes up as the cube of velocity, so when the wind blows twice as fast...one can get eight times more power out. And of course wind is an infinite resource. And unlike fossils - which are having an increasingly destructive impact on this planet - drawing energy from wind does no harm to mother Earth. Some people get very upset about windmills killing birds...but fossil fuels are most assuredly killing way more birds...and causing many to go extinct. So opposition to windmills is really quite silly in that regard.

A possible solution to the noise issue comes from the world of nature. The wings of owls are exceedingly quiet; virtually silent; so they can pounce on a mouse without being heard coming. Evolution gave them the ability to fly very quietly.

So imagine that quite nifty natural technology - which makes an owl's wings virtually dead silent as they swoop through the air - applied to a windmill blades. In other words, put an artificial surface on the blades that's very similar to the feathers found on an owl's wings. Perhaps...even big windmills could be rendered almost silent, as well. Then the 'whoosh whoosh whoosh' would become...............

Barely audible. And one would expect the complaining to stop.


Rod, people would find other things to complain about. I just got back from a 6 week trip to Germany and I did not hear a single complain there about the Windmills. I stayed in private homes with a mill only a 100 m away and it was not an issue, neither to me or the people who live there. There you can see thousands of those mills all over the country as well as whole roofs covered with solar panels making good use of "free" energy and the people can SEE the benefit instead of bitching about it like here. I guess it takes an open mind to see the benefit. I happen to live close to train-tracks and have to listen to the horrible loud blowing of the horns from the trains, day and night, but not a single complain about that in spite of people unable to get proper sleep. They say its for people's safety - haha ... suicidal and stupid people do what they do anyway - with or without horns, lol.
If you spend any time around electrical windings you will notice a "hum" or in the least feel it. The problem is subsonic in nature, close to, or below our ability to hear. Can windmills be silent, no. This low frequency "hum" (noise being essentialy vibrations) is inherent with magnatism. We have evolved adjusted to the earths magnetic field and now we've added a new source over the last century or so. Our bodies have lots of elements that can be affected by magnetism probably with adverse results. So in essence I think you are barking up the wrong tree looking at audible noise. Maybe Briano has some thoughts on the issue.
I have not experienced long exposure to windmill noise. Experientially, I think I felt that certain vibrations (like noise) were not pleasant in the past once or twice. Ergo, it is quite possible that long-term noise/vibrations may not be comfortable to sense and that they may come from windmills.
lleahcc