Whilst renewables are clearly essential in so many ways, it's vital that we understand all their effects, positive and negative. Giant wind turbines have three downsides, of which potentially the most serious is noise.
The first downside is visual. Anyone who's visited Denmark can testify to the visual blight huge turbines create. This can of course be overcome by offshoring or placing in sensitive locations - though wind does usually demand prominence.
The second is ecological. I am not an expert but I believe some birds are being killed (though at the moment the numbers appear to be small compared to, say, deaths from domestic cats), and it seems likely that ecosystems are being disrupted in other ways. This is not my field but I'm sure there are effects and that people are investigating them.
The third downside is aural. The noise of those giant blades can be loud and can travel a long way from the turbine: people living up to 2 km away have reported disturbance, with predictable effects on sleep and elevated levels of stress and annoyance. The World Forum for Acoustic Ecology regularly has discussions of the topic for anyone interested - you can join here - and there is also a growing body of academic research. An expert panel review in 2009 (sponsored by the wind turbine manufacturers) found no adverse health effects though it did admit that annoyance results – rather disingenuously the panel concluded that 'annoyance is not a disease'. This ignores the findings of the WHO that long-term exposure to noise, working through the mech`nism of stress and annoyance produced, does lead to increased incidences of many diseases, including heart attacks, strokes, gastric issues, depression and more.
The evidence against wind turbines is patchy, maybe because the big bucks from industry are all paying for evidence that supports wind energy. Dr Nina Pierpoint's book Wind Turbine Syndrome may have been based on a small sample, but we should not dismiss collections of individual, qualitative evidence, and it does seem that she is becoming a magnet for a growing, though still small, number of personal testimonies of major negative noise effects from around the world. I know from my years studying the effects of sound that in general very few people complain about noise: for example, noisy shops could claim (just like the wind industry does) that nobody complains, implying that there is no problem – and yet many retailers are losing up to 30% of potential sales as people leave the store faster or don't even enter, often without being conscious of the reason for their behaviour. We have become used to suppressing noise, so it should come as no surprise that there are few complaints about wind turbine noise. This does not mean there are no adverse effects.
Giant turbines, especially the older ones, create two sounds in my experience: a tearing sound as the blades rip through and also a thumping bass sound, both of which are not constant and therefore are probably as irritating as a dripping tap (though much louder) and as hard to ignore. Research shows that sound we can't control, and particularly regular, intermittent sound like this, is the most annoying and affecting. There is also the possibility that infrasound (ultra low frequency noise) is in play, though the jury is out on this whole topic. Much more impartial research is needed to defuse the current pro v anti posturing, where individual campaigners like Dr Pierpoint claim devastating effects and industry consultants like Dr Geoff Leventhall dismiss any negative effect at all. I suspect the truth, as so often, lies somewhere in the middle. It would be odd if high energy, low frequency vibrations did not affect human beings in some way given that we're entirely composed of vibrating matter, though probably some people are more susceptible than others, just as with audible noise. Dr Pierpoint wants a 2 km gap betwen turbines and people's houses. This may be on the high side, but from my experience I can say that I would definitely not want to live close to one, and certainly not within 1 km, whatever the pro-wind research says.
For wind turbines, the phenomenon of super-additivity (cross-modal effects where one sense multiplies the effects of a stimulus in another) seems to be in play, and is an issue which has not yet been addressed by any of the research I have seen. The visual pollution seems to be making people more sensitive to the aural; the annoyance factor seems to vary with the context, for example the profile of the location, with rural areas and hilly or rocky terrain increasing the likelihood of annoyance.
It's a balancing act of course... each energy source has its pros and cons, but it is important we know what they are before diving in head first, as the Japanese experience with nuclear power has just shown: industry experts were categorical that Fukushima was earthquake-proof when it was constructed, and they were wrong. In the UK there are now such large incentives for farmers to erect turbines that it pays for them not to farm land and instead to lease it for wind power; once erected, these things are not so easy to remove. The noise effects are as yet unclear, so I do believe we urgently need to know far more about this before we cover our countryside with wind farms.