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Renewable Impacts

By Dave Elliott

It has been an eventful year for renewables. While progress continues apace, with renewables now supplying around 15% of electricity in the UK and 22% of global electricity, in this pre- Xmas post, rather than spelling out all the good news, I will look at some of the less good stories from the year- concerning wind power and CSP.

There has certainly been no shortage of negative media commentary on wind power, with, in addition to the familiar complaints about visual intrusion and costs, a report claiming that wind turbine fires are ‘ten times more common than thought’:

The study, published in the journal Fire Safety Science, used data compiled by the Caithness Windfarm Information Forum (CWIF), an anti-wind lobby group, which had recorded 200 cases of turbines catching on fire between 1995 and 2012, implying 11.7 fires per year. And the study suggested that this could be a significant underestimate.  But one of its authors, Guillermo Rein from Imperial College, put that in perspective: ‘By comparison with other energy industries, fire accidents are much less frequent in wind turbines than other sectors, such as oil and gas, which globally has thousands of fire accidents per year.’

There have been deaths due to on-site accidents during the installation or maintenance of wind turbines,around 140 globally so far, and tragically, 4 people died earlier this year after their single-engined plane hit a 1.5MW GE wind turbine in South Dakota. But RenewableUK pointed out that ‘No member of the public has ever been injured by a wind turbine in the UK.’  

However, some other renewable energy projects have recently met with what could be more serious local problems, in relation to impacts on wild life. The new $2.2 bn 392MW Ivanpah Concentrating Solar Power plant in California’s Mojave Desert seems to be having a lethal impact on birds who fly into the focused beams near the central power tower, with many hundreds reportedly being incinerated or badly burnt mid air. The developers says there were 321 bird deaths between January and June 2014, not all due to the solar flux, but others claim that the annual toll could be several thousands, with 28,000 being quoted from an expert from the Center for Biological Diversity environmental group:

Clearly there are disputes about the numbers. That may be because, according to some of the more lurid coverage, birds are being vaporized leaving nothing behind, although singed carcasses have been found. Otherwise all that can be seen, it’s claimed, are ‘streamers’, one every two minutes – brief puffs of smoke. Although it has been countered that some of those may be insects or airborne debris catching light.

You would think birds would avoid hot spots, but Federal wildlife officials said the plant may be acting as a ‘trap’ for wildlife, with the bright light attracting insects (as street lights do), which then attract insect-eating birds that fly to their death in the intensely focused beam. The plants developer, Brightsource, has tried to put all this in perspective:  So has CSP today:

What can be done? Airports already have to deal with bird strike problems, and acoustic bird scarers are a possible remedy: clever new ideas have emerged: and            And later it was noted that one remedial strategy was to reduce the spread and intensity of the solar flux by adjusting the mirror focus:

Dish and trough CSP designs would presumably avoid the problem- the heat focus is smaller and more contained. But for big sun tracking-mirror arrays, focused on power towers, location is clearly all-important. The California Energy Commission is being urged to block a large CSP project near the Joshua Tree National Park in California, with a power tower 75 storeys high, located on a migratory flight path between the Colorado river and the Salton sea.

Animal deaths due to human interventions should clearly be avoided, but the solar deaths have to be put in perspective: nearly a billion birds are estimated to die from crashing into windows in the US each year and many more are killed by cats.

Some birds are also killed by wind turbines, although a recent study updated earlier studies, which had been based on older machines, and found that with the advent of modern larger slower moving wind rotors, the numbers were low and, in the case of N America, not biologically significant, representing under 0.01% of the small bird (passerines) population. There have also been concerns about impacts on bats, who evidently think wind turbines are trees, but there are also ideas for resolving that:

In another scare, infra sound health impacts have been claimed for minks farmed for fur in Denmark, near (328 meters from) a recently installed 4 turbine wind farm. It has been blamed for 1,600 premature births, with some exhibiting deformities, and many being stillborn: There have also it seems been cases of cannibalism- mothers eating offspring.

This all sound horrendous. But there might be other explanations than infra sound. Minks apparently suffer from a range of illness, some of which can produce similar results, which may be worsened if they are in captivity. Some might ask, should we be farming minks? But it is possible that minks may be more sensitive to infrasound in some way, and if a link is proven, it is clearly very worrying: this evidence, if proven, may have alerted us to a wider problem.

There have certainly been claims that low frequency infra sound from wind farms impacts on humans, causing sleep disturbance and a range of illnesses, although this has been strongly rebutted. For example, the are many other sources of infra sound (most machines can produce it). One commentator noted that, typically, a child on a swing can experience infrasound at a level of around 110dB and frequency 0.5Hz, much higher than wind turbines emit, with no ill effect, and no one suggests banning swings as a result:

The Mink farm case has been cited extensively by the World Council for Nature: It has also made much of alleged health impacts on humans due to wind farms: It seems very single minded on all this, calling for a moratorium on wind farms, but, amongst its other environmental concerns, also seems to have a wider agenda: it says that ‘contrary to what green activists, corrupt politicians and wind-farm salesmen tell us, the science is not settled on climate change’

The evidence on wind turbines noise and health impacts has usually been anecdotal so far, and mostly about audible sound, not infra sound, although much relayed by anti-wind groups and the media. Views and reports on wind farm noise in general have clearly differed, with some seeing it as a major issue, while others say its only worrying to those that don’t like wind turbines for other reasons. For example see and

The industry view, backed up by some studies, has been that noise isn’t a significant issue: And overall, the noise issue does seem to have been over-hyped and perhaps even distorted:

However that’s not to say that there are no impacts, and some people are clearly more sensitive to noise than others. A precautionary approach seems wise:

On that basis, given the possible new evidence from the Danish minks, it may have to be looked at some more. There is apparently a study planned in Scotland which might clear the air : DECC have also asked the Institute of Acoustics to do a new study of wind turbine noise generally.

If some types of wind turbine related noise really are a problem, before we start thinking about new locational policies, with wider separation from human habitation, there may be technical solutions. For example, low frequency, and other noise problems due to blade stalling with some wind turbines, might be avoided by simple software changes and revised operational patterns: and

Renewable energy technologies, like all technologies, do have impacts, but as the examples above illustrate, they are local rather than global and hopefully can be reduced or avoided. That can’t be said of fossil energy technologies- their use has both local (air pollution) and global (climate) impacts and although there may be ways to reduce or store some of their emissions, there is no way to avoid them, apart from not burning fossil fuels. We mustn’t be complacent about the local impacts of renewables, for example on birds and bats, and we have to reduce them as much as possible, by sensitive choice of location and technical adjustments, but they have to be put in a wider perspective. Climate change and air pollution from fossil fuel burning is likely to have a very much larger impact on wild life, and humanity, than the use of renewables like wind and solar.

*This post is a bit early, since I’m just off on Xmas holiday…Enjoy yours!

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One comment to Renewable Impacts

  1. Dave Elliott

    This may explain why the Barnard web site link above doesn’t work any more:

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