Wind power problems,
alleged problems and objections

Is wind power the answer to greenhouse and climate change?

The Australian Electricity Generation Report 2008 from The Climate Group stated that South Australia was the only eastern state to reduce its greenhouse gas production in that year (a fall of 6%); this was mainly thanks to wind power taking the place of some of the fossil-fuelled generation. More recent reports, including one in 2011 by the Australian Energy Market Operator (AEMO) showed that this trend has continued.

Our society must not confine itself to building wind farms, we must also:

• Reduce wastage of energy and unnecessary energy use; this will require a massive change in thinking for most people;
• Walk or ride bicycles more, not only will it save greenhouse gasses, it will improve our health and make our cities and towns more pleasant places in which to live;
• Develop other renewable energy sources;
• Modify our electricity supply system to make it more compatible with sustainable electricity;
• Reduce unnecessary use of private cars – use cars that are no bigger than we need, move toward highly efficient cars such as hybrids, or use electric cars powered by green electricity. Again, an enormous change in priorities and thinking is needed;
• Make our housing less hungry for energy and run our houses with more consideration given to power consumption;
• Improve public transport;
• Cut down on unnecessary consumption;
• Cut down on unnecessary packaging;
• Reuse rather than throw away;
• Recycle where we can't reuse.

Substantially increasing the price of energy would probably be the simplest and most efficient way of achieving most of the above points.

Wind turbines are not noisy

Also see People driven from their homes?

If you are on a country road, there is a light breeze and there are wind turbines two kilometres away, you will probably be just able to hear them. If there is a strong breeze then you probably won't hear the turbines because of the noise the wind is making in nearby trees or shrubs. If there is a car travelling on the road within one or two kilometres, again, you probably won't hear the turbines, because of the noise from the car.

	Annoying sounds Sounds can be annoying while not being particularly loud. For example, at night a neighbour's 'loud' music can stop one from sleeping even though it is not a lot above the threshold of audibility; if you can hear it at all it can be annoying and prevent you from sleeping. In contrast, the sound of surf can be restful. It seems that a sound that varies in a random way might be more easily tollerated than one that varies systematically; even traffic noise, though unpleasent, is tollerated by most people. Wind turbine sounds might affect some people in the same way as does a neighbour's 'music'. Some sounds are more annoying than others and different people can react very differently to the same sounds. "Noise absolutely horrible" Mr Bill Quinn, who appealed against one of the South Australian Hallett wind farms was quoted in the Flinders News (Port Pirie, 2011/11/23) as saying that "The noise coming from Hallett #2 [wind farm] was absolutely horrible." He lives three kilometres from the wind farm, but his mother lives two kilometres from some of the turbines. Mr Quinn said "Some nights [his mother] has to turn the ceiling fan on to drown out the noise". If the wind turbine noise could be drowned out by a ceiling fan, which in my experience are very quiet, it could not have been loud. Erroneous readings I have heard it claimed that sound levels of up to 100 dB have been measured 3 km from wind turbines. Such readings can only be explained as being due to someone not familiar with sound meters allowing the wind to blow over the microphone.
	Some noise levels compared Source/Activity Indicative noise level dB (A) Threshold of hearing 0 Rural night-time background 20-50 Quite bedroom 35 Wind farm at 350m 35-45 Busy road at 5km 35-45 Car at 65km/hr at 100m 55 Busy general office 60 Conversation 60 Truck at 50km/hr at 100m 65 City traffic 90 Pneumatic drill at 7m 95 Jet aircraft at 250m 105 Threshold of pain 140 From a wind farm fact sheet published by The Australian Greenhouse Office and the Australian Wind Energy Association.

Wind turbines are not loud in the sense that pneumatic drills and jet engines are loud. Sound levels from turbines are typically no more than about 55 dB (A) when measured at a distance of about 100 m; this is the same level of sound as you can expect from a car traveling at 60 km/h at the same distance. Sound levels always decline with distance; the rate of decline usually follows the inverse-square-law – twice the distance a quarter the sound, three times the distance a ninth the sound, etc.

Wikipedia states the following:

"Modern large turbines have low sound levels at ground level. For example, in December 2006, a Texas jury denied a noise pollution suit against FPL Energy, after the company demonstrated that noise readings were not excessive. The highest reading was 44 decibels, which was characterized as about the same level as a 10 mile/hour (16 km/h) wind."

An expert panel review of "Wind Turbine Sound and Health Effects" conducted for the American Wind Energy Association and the Canadian Wind Energy Association is available from American Wind Energy Association. It describes the source of wind-turbine noise in some depth.

Wind Turbine Noise, Infrasound and Noise Perception by Anthony L. Rogers, Ph.D. from the Renewable Energy Research Laboratory of the University of Massachusetts at Amherst is an interesting and informative presentation.

The Acoustic Ecology Institute's "Wind Farm Noise 2011: Science and policy overview", compiled by Jim Cummings, makes the point that several scandanavian studies have shown turbine noise annoyance is notably higher in rural settings than in more built up areas.

Infrasound: low frequency noise

Sonus, an acoustics consulting firm based in Adelaide, produced a report on infrasound measurement from wind farms and other sources for Pacific Hydro in November 2010. This report showed that infrasound levels from wind turbines was less than that from beaches, a power station, and that typical of a central business district of a city.

Summarising statements from the publication by Anthony Rogers, mentioned above, it can be said that infrasound from modern wind turbines is not perceptible to humans at more than about 120m from the turbines. Rogers states that "The ear is [the] most sensitive receptor of infrasound" and "If it can't be perceived, it has no effects". "Infrasound is emitted from modern wind turbines, but is NOT a problem."

It is worth noting that surf is a major source of infrasound, and most people would consider the sound of surf to be restful rather than disturbing; certainly the sound is not considered harmful.

Peter Seligman on infrasound

"... the hearing and vestibular systems are subjected to very high levels of body generated noise. These include, walking, breathing, heartbeat, chewing and head movement. Body noises generated in this way were a problem in the Cochlear Ltd project to develop a fully implantable cochlear implant. In this case the microphone was implanted subcutaneously behind the ear. The level of infrasound picked up from the body by this microphone was a major problem and far exceeded all sound from external sources. In fact turning the head or chewing were some ten times louder than the external sounds we were trying to pick up.

So it is being held that levels that cannot be measured and cannot be heard, are problematic. In contrast, everybody is subjected to far higher internally self-generated natural infrasound levels which clearly, are not a problem. Typically, walking subjects the body to accelerations of about 1 g, at a frequency of about 2 steps per second, ie. 2 Hz. Translated into sound pressure, this acceleration is subjecting the body to infrasound at about 196 dB."

My own experience, research and opinion on wind turbine noise

I have camped overnight beneath the turbines of Starfish Hill (1.5 MW turbines) and Clements Gap (2.1 MW turbines) wind farms and had no problem at all getting a good night's sleep; I found the sound of the turbines, if anything, to be relaxing. I recognise that this is subjective and that the experience of others may be different.

I visited Toora in late April 2008, staying in the caravan park at the foot of the hill on which the Toora Wind Farm (1.75 MW turbines) is built. My impression when I was close to the turbines was that they might have been a little noisier than most others I have visited, but even so, they were barely audible from the caravan park (840m from the nearest turbine), and then only once in a while.

Clements Gap Wind Farm

On 2010/07/19 I visited the six houses that were closest to Clements Gap wind turbines. I found occupants in three of these houses. The distances that these people lived from the nearest turbines varied from 1000 m to 1600 m. All three people reported being able to sometimes hear the turbines from outside their homes, but they also said that they could not hear the turbines from within their homes. They said that they had no problems from the turbines. (All three people received income from turbines on their land.) During this very small survey the breeze gradually increased from light to stiff; I was able to hear the turbines from 1600 m in a light breeze, but not from 1000 m in the stiff breeze; house occupants confirmed that the turbines were more easily heard in light than strong winds (apparently because of the higher level of environmental noise in a strong wind).

I have taken sound level readings at Clements Gap Wind Farm (2.1 MW turbines) on several occasions; I recorded a maximum of 54 or 55 dB(A) at a distance of around 100 m from a turbine and the same immediately beneath a turbine. The sound levels at distances of 300-500 m were in the 40s, and at one or two kilometres, while the turbines were audible, my meter did not register a reading (it has a mimimum of 40 dB). On all these occasions the breeze varied between light and strong (interestingly I didn't get a higher sound reading 100 m from a turbine in a strong breeze than in a moderate breeze; 55 dB under both conditions).

On two occasions I noted that when I was about two kilometres from the turbines they were barely audible; I have never heard turbines from a greater distance than 2.5 km. I have never recorded sound levels greater than 55 dB even directly beneath a wind turbine.

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On a visit to Wattle Point Wind Farm, where 55 (1.65 MW) turbines are arranged in a grid with several public roads passing between the turbines, I recorded a maximum of 47 dB(A) among the turbines. I also noted that a car travelling at an estimated 60 km/hr 400 m from me was much noisier than the turbines that surrounded me.

The Hallett Hill Wind Farm (2.1 MW turbines) has been involved in controversy, some of which involved alleged noise problems. On a visit in May 2011, while all the turbines were turning, my sound meter did not register a reading over 40 dB at any of five ploints on the public roads that go closest to the turbines. The turbines were inaudible to me at the township of Mount Bryan, at a distance of 3.8 km.

My impression is that the sound of turbines at 1000m would be less, less constant, and much less annoying than traffic noise anywhere in a large city. I'd prefer the sound of wind turbines at 1000m to the noise of a neighbour's kid riding a trail bike, or a quad bike being used to spray a neighbouring vineyard, or bird scaring guns in neighbouring vineyards; all sounds that I hear periodically and are small annoyances.

In a country like Australia, with no shortage of good sites for wind farming, no wind turbine should be built within one kilometre of a home without the informed consent of the owner. To build turbines less than one kilometre from a home would be to risk making the lives of the people in that home less pleasant.

Claims of ill-health due to turbines are questionable and it is very difficult to see why wind turbine noise should be any different from other environmental noise such as that due to traffic or even wind in trees or wires.

People driven from their homes by wind turbines?

In September 2011 I was sent a map of a part of the Waterloo wind farm area showing the line of the turbines and the 'abandoned houses'. (The map was displayed here, but on 2012/02/10 the person who sent me the map asked me to remove it. I have done so.)

A little consideration of the map raised some questions. Three of the houses involved were 3.5 kilometres from the turbines and the forth, 4.5 km away. The greatest distance from which I have ever definetly heard turbines is 2.5 km, and then only in ideal conditions. So I found it very hard to believe that a (Vestas) turbine built (and presumably commonly used) in Denmark, where many would be in close proximity to houses, could be so noisy.

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There are laws in South Australia, and probably all other Australian states, about permissible noise levels from wind turbines; so in cases where noise levels were excessive the owners would have a legal right to compensation. (The Waterloo Wind Farm has been found to be compliant with the SA EPA guidelines.) This would seem to be an argument for legislating for maximum noise levels at homes rather than, as in Victoria, NSW, and proposed by the SA Liberal Opposition, a minimum 2km distance between homes and turbines.

Homes in small country towns often have very low market values; similar houses in nearby larger country towns have much higher values. The larger towns are seen as more desirable places in which to live; they have many shops and services that the small towns lack.

Speculation Are some of the people claiming noise and/or health problems actually wanting to move to a more desirable location and get a higher amount of compensation for their houses than the normal market price? (In the Waterloo case, I have been told that at least one of those who 'was driven from his home' had previous plans, quite unrelated to the wind turbines, to leave.)

This also relates to the question of Land values and wind farms; plainly, if a house truly had been abandoned due to noise nuisance, its value on the market will drop substantially.

A good night's sleep at Waterloo I went to the Waterloo wind farm on the evening of 2012/02/10 and set up my swag beneath one of the turbines. The number of kangaroos on the ridge impressed me; I must have seen at least eight, including a small joey. I also saw a pair of wedge-tailed eagles circling near the turbines. All were aparently in good health. The wind varied from a moderate to a stiff breeze, so the turbines were operating all night. While I could plainly hear the turbines whenever I woke at night, I had no problem at all in getting a good night's sleep. Right at the foot of the turbine the sound of the turbine gear-box dominated the sound of the blades as they passed through the air. I noticed that when I moved away 100m or more all I could hear was the blades. When passing through Waterloo in the evening I stopped my car and listened for the turbines. I could not hear them. The breeze in the nearby trees was making a fair amount of sound. In the morning I again passed through Waterloo and stopped. There was still a stiff breeze on the ridge where the turbines were, but very little air movement in Waterloo. I thought I might just be able to hear the turbines, but could not be sure.

Compensation

Natural justice demands that people whose amenity has been seriously impacted by noise from turbines should receive some sort of compensation. But if one person is compensated, how do you stop others who may be similarly placed in relation to turbines, but not have any real problems with them, jumping on the band-wagon and demanding similar compensation just because they think they can get it? How do you treat people who might honestly, but erroneously, believe their health has been impacted by wind turbines? Leave it to the courts?

The power given to Victorian householders to veto any proposed turbine within 2 km is not an answer because all the power is with the householder and none with the wind farm builder; there must be a balance. Many people live perfectly happily with wind turbines much closer than 2 km.

Should compensation be based on recorded noise levels, the difference between ambient noise and wind turbine noise, or something else? Ideally, it should depend on the true impact on the individual; but how to measure that?

Do wind farms cause social conflict?

The Central Western Daily (Orange) reported on 2011/12/05 that Blayney mayor Bruce Kingham stated that "In the 11 years since the [Blayney] wind farm [was built], we have had not one complaint".

Don Quixote de la Twenty-first Century I saw this cartoon in ReNew and couldn't resist copying it here. The original was aimed at the NSW Government which, as well as cutting the solar power feed-in tariff, has shown anti-wind power sentiments.

Clements Gap Wind Farm, 15 km from my home, has not caused any social conflict that I know of. On the other hand there is social conflict concerning wind farms such as Mount Bryan, a little further to the north-east, and Waubra, in Victoria.

The arguments for and against proposed wind farms do, no doubt, cause enmities. This is unfortunate, but probably unavoidable; many people see wind turbines as a part of the answer to the greenhouse/climate change problem, others see them as a blight on the landscape. The fact is that any industrial development, especially a conspicuous one, is likely to lead to some conflict in some cases.

Considering the fact that social conflict only arises around some wind farms – only those where opposition develops – isn't it just as valid to say, "wind farm opponents cause social conflict", as it is to say "wind farms cause social conflict"?

Envy

Paucity of information from operators

AGL "Information Centre", Burra Supposedly open Monday to Friday 1100 to 1500hrs. (Note the big sign painted on the window stating "Now open", visible 24 hours a day.) When I was there, 1100 to about 1330hrs Friday 2009/02/13, there was no sign of life. To do justice to AGL, their SA Manager of Power Development, Tim Knill, has been very helpful.

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Many wind farmer's Net sites give minimal data and are rarely updated. Internet sites are easily and cheaply updated and the operators must have the information. One wonders why they are so stingy about sharing it.

Ignorance of the facts of wind power is obvious in many wind power opponents. For example, I have read from opponents several times that wind farm construction uses huge amounts of water; this is not true, but it is difficult to get actual water consumption figures from wind farmers.

The companies that do the earth works for wind farms seem even less comunicative than the wind farmers themselves.

Those companies that make little or no effort to inform Australians on the facts about the wind farms that they are proposing, and wind power in general, are doing a disservice to informed discussion and, in the long run, are letting down their industry.

Several of those people in the wind industry who have provided information for these pages have done so on the condition that I don't disclose their names, several others didn't want me to publicise their email addresses. In the interests of credibility I would like to be able to attribute the data on these pages, but the lack of openness in the industry makes this impossible in many cases.

Wind power generation graph for August 2007 from Wonthaggi, Victoria Acknowledgement, Wind Power Pty. Ltd. So far as I know, this sort of data is no longer available from any wind farm in Australia (although it can be obtained from the AEMO).

Some in the industry only provide information in the form of PDF files; in some cases these are so large that anyone on a limited download plan, or only mildly interested, would not look at them (for example TME Australia had one that was 5MB). HTML can be much more efficient; this page, for example, including images, is about 500kB (it is one of my largest pages).

Most, if not all, wind farm operators do not like to release the records of the amounts of power that their wind farms generate. A common claim from many wind farm opponents is that wind farms do not generate significant amounts of electricity. How can the public gauge the truth while the wind farm operators hide the facts?

It was in response to this lack of easily accessible information that in late February 2008 I started expanding my wind farm pages – which previously had mainly concentrated on wind farms in South Australia – to cover the whole of Australia.

Unbiased studies into bird and bat impact, the effect of wind farms on property values, noise, sunlight-chopping, etc. should also be made easily and freely available. This is the responsibility of government as well as the wind industry.

Do wind farmers consult sufficiently with local communities?

In my own experience Pacific Hydro who built the Clements Gap wind farm in the Crystal Brook area, consulted widely with the local communities. Roaring 40s, the developers of Waterloo, Stony Gap, and Robertstown wind farms also seem to be making a good effort to inform the local people.

There have been complaints that the wind farm companies explain rather than consult; that they tell people what is going to happen rather than ask what should be done. In my experience this is true. But wind turbines must be built in the best places to build wind turbines; there is not a huge space for compromise if a wind farm is to be economically viable.

Communities are made up of individuals. Each individual who lives near a proposed wind farm will have an opinion on where turbines should, and more to the point, should not be built. Aesop said something to the effect of "He who tries to please everyone will please no-one".

The people of Australia demand copious amounts of electricity. The climate change problem demands that we reduce our carbon intensity. Wind power is one of the most technically advanced and competitive forms of renewable energy available. Of course the concerns of the local people should be listened to, and if there are consensuses to be found, they should be complied with if this is a practicallity, but ethically, isn't there an obligation to aim at the greater good – of everyone and the world as a whole – rather than sacrificing the greater good in order to try to please all the local people?

Do wind farmers support local communities?

I inquired about this, but did not receive a response (AGL have not responded to a number of my inquiries).

Most wind farmers do support the local community. For example, Pacific Hydro, which has built a wind farm near my home town, Crystal Brook, gives $50 000 each year for community projects for the life of the wind farm. Also see community funding by wind farmers.

Wind turbines are as long-term a source of sustainable energy as anything else

In fact modern (~2012) wind turbines, including the blades, have an expected life span of around 20 to 25 years; typical solar photovoltaic panels are guaranteed for twenty years, and then with a decline in productivity written into the guarantee. Solar thermal or concentrating photovoltaic systems have not been around anywhere near twenty years so their life-spans are unknown, but I would think they would be unlikely to last any longer than 25 years, at least without major rebuilding.

It is quite possible that wind turbines will last longer than 25 years, but the technology is improving quickly and typical 25-year-old turbines have become obsolete, Salmon Beach, Esperance, WA, for example, became obsolete in 15 years.

Other sustainable energy systems, tidal, wave and hot-rock geothermal have not yet reached ages such as twenty or 25 years, but again they would be unlikely to last any longer than that. Hydro-power stations last longer than 25 years, but even they must need major maintenance at periods of a decade or two.

There is no one solution to our current dilema, reducing energy consumption should have a higher priority than building wind farms, but wind power is just as much a long-term solution to the sustainable energy problem as is any generation technology.

Efficiency of wind turbines

Power curve of a Suzlon S88, 2.1 MW turbine Data from Suzlon

At the most wind turbines convert somewhere around 40% of the power of the wind that passes through them into electricity. The energy of the wind is in its movement; to take all the energy from the wind would be to take all the movement from the air; with a little thought you can see that this would be quite impossible. The theoretical limit to the amount of power that a tubine can take from the wind is 59%; this is called the Betz limit.

In the case of fossil fuels, efficiency is very important. Fossil fuels are a finite resource, we can only use them once and then they are gone; and when burned they release pollutants into the atmosphere. It is essential that we minimise the amount of fossil fuels we burn and maximise the amount of energy that we extract from every tonne that we do burn.

Defining efficiency in the case of wind turbines

What is lost if wind turbines take relatively little energy from the wind?

The amount of power generated by actual Australian wind farms is given at Power generation of wind farms.

Energy in wind

Consider the power curve shown in the graph above (and the table on the right). It shows that when the wind velocity rises above 14m/sec the turbine does not generate more electricity, in spite of the fact that the energy in the wind increases.

We can calculate (from the cube relationship mentioned above) that this turbine is at its most efficient, in the sense of taking the greatest proportion of the available energy from the wind, at a wind speed of about 8m/sec. We can then calculate how its efficiency varies at other wind speeds, relative to that. This is laid out in the table on the right.

Note that if this wind turbine is 40% efficient at a wind speed of 8m/sec then it is only 3.6% (0.09×40%) efficient at a wind speed of 24m/sec. That is to say that it takes proportionally very little energy from the higher speed winds.

Relative efficiencies of a Suzlon S88, 2.1 MW turbine at a range of wind speeds Data from the table above

The graph at the right shows that a typical modern turbine takes the greatest proportion of available energy from the wind at a wind speed of 8m/sec. At this wind speed the turbine is probably taking about 40% of the available energy from the wind. If we call this a relative efficiency of 1.0 the relative efficiencies at other wind velocities can be calculed (efficiency being defined as the proportion of the available energy being taken from the wind).

So while the turbine does not reach its maximum rate of electrical generation until the wind speed gets to about 14m/sec, it is at its maximum efficiency at much lower wind speeds.

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If wind power is any good, why does it need subsidies to compete?

Sustainable forms of power (including wind) require more work and more infrastructure for the same amount of power generation compared to fossil fuel power stations – thus have higher costs – but do not have the environmental problems associated with fossil fuel power.

If the fossil fuel power generators had to either stop dumping carbon dioxide into the atmosphere or pay for cleaning up the environmental damage that this causes, they could not compete economically with wind power.

While wind farmers get a premium for the power they generate, they do not get government money to build the wind farms.

Do wind farms get government money?

(Also see Why does wind power need subsidies?; above.)

Wind farm opponents sometimes make the claim that wind farms receive large parts of their funding from government. While it is true that, because of the lack of a level playing field, wind farms cannot compete with fossil-fuelled power stations in terms of dollars per MWh of the electricity generated, I believe that very little government money goes into building wind farms.

The only exceptions I know of are one or two very small community owned wind farms that might have had significant government funding.

In general, wind farms are built with private money. However, they cannot compete with fossil-fuelled power stations so long as the latter are allowed to dump their wastes into the atmosphere without charge. The electricity from renewable energy power stations is generally more expensive than from fossil-fuelled power stations, so electricity retailers have to have incentives to buy renewable energy.

I have recorded some estimated electricity costs by energy source on my Sustainable Energy page and the costs of wind power in particular are discussed on my wind power page.

Timing of wind power generation
Do wind turbines generate power when it is most needed?
Can wind power provide base-load or peak-load?

Peak load

Base load

How does this relate to wind power?

The fact that more than 20% of South Australia's power was produced by wind farms in 2010, and greenhouse emissions from power generation in SA declined by about 20% from 2005 to 2010, with no reduction in power reliability, proves that renewable energy can provide a substantial part of Australia's electricity needs and produce a positive contribution to the climate change crisis.

Gas-fired generators are relatively cheap to build, although expensive to run and damaging to the environment because of their greenhouse gas production. These are the most common way of 'filling in the gaps' between power generation and demand in Australia.

A more environmentally friendly way of generating power at peak load is pumped hydro. Alternatively demand-side management of the electrical supply system could be implemented, where some of the loads are controlled to suit the level of supply.

One of the advantages of solar power in Australia is that its maximum output occurs on the sunniest days, which are often also when the higher power demands come; although by 5 or 6pm, at peak load, their power generation is very much in decline.

Starfish Hill Wind Farm The fire of 2010/10/30 Image credit Fleurieu Multimedia

Fire hazard without wind turbines It should be recognised that climate change, if unabated by changing from fossil fuels to renewable energy, will result in far greater increases in fire hazard. Scientific American, June 2011, carried an artcle stating that fire danger in the western US states will increase up to six fold with just one degree higher average temperatures. Lightning strike A common cause of fires in Australia is lightning strike. This risk will be significantly reduced in an area where the ridge-tops are lined with wind turbines that safely conduct the lightning to the earth.

Are wind turbines a fire hazard?

My rough calculation suggests that there have been getting on toward a thousand turbine-years of wind turbine operation in Australia.

The area around the base of all turbines is kept clear of vegetation (in the case of the proposed Mount Bryan Wind Farm at least, the SA Country Fire Service required a cleared area of 40m × 40m), but a fire in the nacelle, on top of the tower, could result in sparks and burning material falling on the ground at a distance from the tower.

Country fire service units do not have pumps capable of directing water up to the nacelles of wind turbines. Geoff Conway of the Country Fire Authority has said that fires from agricultural machinery at harvest are a far greater risk than wind turbines.

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The turbine access roads would help emergency services access any fire. Some turbines have built-in fire suppression facilities such as automatic flooding with carbon dioxide. This is not used on Suzlon turbines in Australia because of the risk of asphixiation of workers; protecting life is held more important than protecting assets.

Much is made by wind turbine opponents of the 300 L of oil in the turbine gearbox being a fire hazard. This would be true if the fire was due to failure of the gearbox, but I had the piece below from Brendan Ryan of Suzlon:

"I worked for Vestas when one of their turbines burned at Lake Bonney. I remember clearly the inspection crew had checked the inside of the gearbox and found no signs of heat damage even though the whole external nacelle was destroyed."

Television reception and wind turbines

Weather radar interference

Is solar power somehow 'better' than wind power?

Wind and solar power can complement each other In hot weather winds tend to be lighter so wind turbines generate less electricity, at the same time the sun is likely to be shining and high in the sky, and solar power generation would be high. When the sun is not shining the wind is more likely to be blowing.

How should we judge which is 'better'? Logically we need to look at the cost, in both financial and environmental terms, of each in relation to the amount of electricity generated; and we should look at how wind and solar fit the electricity demand cycle.

In 2009 wind must be more profitable than solar. If it were not so then surely we would be seeing solar power stations all over the place instead of wind farms? There is no government bias toward wind power and away from solar that I know of. The people who invest their money in wind farms and the business people running the companies that build wind farms are not stupid.

By the way, a typical utility scale wind turbine has an installed capacity of 2MW and a capacity factor of 34% while the average Australian roof-top solar installation is 2kW and solar PV has a capacity factor of about 16%; so a typical wind turbine will generate as much electricity as 2000 average roof-top solar systems.

A comparison of wind and solar

Operational factors
Factor	Wind	Solar
Generation at peak load	Peak load (or peak demand) in Australia usually coincides with exceptionally hot weather and tends to come at around 6pm as people are arriving home from work, switching on air conditioners and preparing dinner. Wind power generation is lower than average during periods of peak demand because exceptionally hot days tend not to be windy, see Wind Power in SA.	Solar power facilities will be generating at a high rate through the day on hot days, because it is most likely that the sky will be clear, but with the lower sun around 6pm their generation will have greatly declined. Solar PV panel productivity increases greatly with higher light levels, but decreases slightly with higher temperatures. (For more detail on this see elsewhere.)
Capacity factor	The average capacity factor for wind power in Australia is about 34%. That is, a wind farm of 30 MW will generate about a third of its rated capacity, 10 MW, on average.	The average capacity factor for solar photovoltaic systems is around 16% to 18%. That is, a solar power installation of 10 kW will generate about 1.7 kW, or about a sixth of its rated capacity, on average.
Cost
	Wind	Solar
Two proposed projects near Geraldton, WA	Mumbida Wind Farm in WA is expected to cost $150m and will have an installed capacity of 55 MW. Assuming a capacity factor of 34% (typical for SE Australian wind farms) it will generate 164 GWh per year. Neglecting maintenance costs and assuming a 25 year life, this works out at a cost of about 3.7 cents per kWh of power generated.	Greenough River Solar Plant, also in WA, is expected to cost $50m and will have an installed capacity of 10MW. Assuming a capacity factor of 18% (reasonable for a solar PV installations in this latitude) it will generate 14 GWh per year. Again, neglecting maintenance costs and assuming a 25 year life, this works out at a cost of about 14 cents per kWh of power generated.
Based on http://www.abc.net.au/news/2011-08-25/renewable-energy-supplement/2855838
	Wind	Solar
Two actual projects in SA - assuming 7.5% annual cost of capital	Hallett #1 Wind Farm cost $233 million, so the annual cost of capital is $17.46 million. With annual maintenance costs of $6.75 million (from AGL), total annual costs come to $24.21 million. Annual generation is 326 000 MWh, so the cost of the power generated can be calculated as $74.26/MWh, or 7.4 cents per kWh.	The total cost of my roof-top solar system in the Clare area was $8900, so the annual cost of capital is $668. Assuming no maintenance costs, this is also the total annual cost. Annual geration is 2096 kWh, so the cost of the power generated can be calculated as 32 cents per kWh – about four times that of Hallett #1.
Environmental factors
Factor	Wind	Solar
Land covered	Wind turbines occupy very little land, the necessary roads and 'hard-stands' for building and accessing the turbines cover more, but still not large areas for the amount of electricity generated. A typical modern, utility scale, turbine (rated at 2.1 MW) can generate about 6.4 GWh per year.	Solar power is very diffuse. A solar power station must cover a large area if it is to produce a lot of power. This is way outside of my limited expertise, but it seems that the best areas in the world for solar power receive around nearly 3 MWh per year per square metre (for panels aligned to the optimal [fixed] angle for the latitude involved). Assuming an efficiency of 15% (typical of modern crystalline silicon cells), a collection area of 13 000 m2 (say 100 m by 130 m) would be needed to generate the same amount of energy as the 2.1 MW wind turbine discussed in the box on the left.
Site damage	Wind turbines generate the maximum electricity if they are placed on the tops of ridges; rounded, bare ridges being better for wind flow than rocky or tree-covered ridges. Building roads and erecting turbines on ridge-lines carries with it some risk of causing erosion.	Solar power stations can be built anywhere there is a lot of sunshine. Flat areas are cheaper to build on than hills. The solar collectors can be placed where the existing vegetation has little conservation value. However, as mentioned above, they must cover large areas.
Visual	On-shore wind turbines are often on ridges and therefore are conspicuous from long distances. Off-shore wind turbines are expensive, and the further off-shore the more expensive they are.	Home Wind home Top Index Solar power stations can be sited inconspicuously.
Environmental factors continued
Factor	Wind	Solar
Embodied costs	There are environmental costs in mining and smelting the steel from which wind turbine towers are made. Petrochemicals are used to produce the glass-reinforced polimers used for turbine blades: petrochemical industries are notorious for being polluting.	Large quantities of steel are also needed for the support structures for solar collectors. Silicon solar panel production is not without environmental costs. Some advanced solar cells use gallium arsenide; gallium is quite a rare element and arsenic is highly toxic – the ultimate disposal of panels composed of such materials would need to be done responsibly.
Embodied energy	Energy must be expended to build the wind farm and the wind turbines before any energy is generated by the wind farm. I have discussed this question elsewhere on this page. A wind farm will 'pay-back' the energy required to build it in the first few months of operation.	So far as I have been able to find out it takes from two to four years to pay back the energy involved in manufacturing photovoltaic panels, see The Pros and Cons of Various Methods of Generating Electricity.
Water consumption	Wind farms require very little water.	Solar power stations using photovoltaic panels without concentration of sun-light require little water; those that concentrate sun-light and solar-thermal power stations require substantial volumes of water for cooling.

The table above shows that deciding whether solar or wind is the least environmentally damaging is not easy. Also see How does wind power compare to roof-top solar?.

Leakage of oil

Of course the potential of this would be similar to any other machinery in operation, for example, farm tractors and earth moving equipment.

Erosion of sites

Brendan Ryan of Suzlon gave me the following:

"The access roads are built to a high standard, I always joke that you can tell them apart from the local roads as they are in better condition. The drainage plan for the site is well thought out and the road compaction is quite high as well as the forming of the shoulders. Built Environs have to do maintenance work several years after the road is built to tease out any areas that may be an issue such as where ponding occurs. I think if you look at Hallett Stage One after several rain events you will find the roads holding up okay."

I inquired with Built Environs (who have constructed roads and hard-stands on several SA wind farms), but got no reply.

Bird deaths from wind turbines

Two feral cats I won't go into detail, but data on bird deaths at one of Australia's biggest wind farms, Waubra (see below), and a Government study on Macquarie Island suggests that two feral cats would kill more birds than all the turbines at Waubra.

In the long term every wind turbine saves bird's lives by slowing the climate change that will be a far greater bird killer.

The recorded rate of bird mortality associated with three Australian wind farms is between 0.23 and 2.7 birds per turbine per year. Far more birds are killed in collisions with steel-lattice towers, power lines, house windows, cars etc. Several of the world's bird protection organisations hold that climate change is a far greater threat to birds than are turbines.

Graph from the UK Centre for Sustainable Energy, data from A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions; Wallace P. Erickson, Gregory D. Johnson and David P. Young Jr.

Quoting from a fact sheet published by the Australian Greenhouse Office and AusWEA (Australian Wind Energy Association)...

"A US study published in 2001 carried out by Western Ecosystems Technology puts wind turbine collision into perspective with bird collisions with other structures: [deaths per year?]

• Vehicles: 60 million to 80 million bird deaths
• Buildings and windows: 98 million to 980 million
• Power lines: tens of thousands to 174 million
• Communication towers: 4 million to 50 million
• Wind generation facilities: 10 000 to 40 000

The study estimates that wind farms kill an average of 2.9 birds per turbine per year in the US – equivalent to less than 0.02% of the staggering 200-500 million collision related [bird] deaths in that country"

• There are many more small turbines in the US than in Australia;
• Many older US turbines have steel latice towers, similar to those of communication towers, while all industrial scale Australian turbines have solid steel tube towers;
• Being smaller, US turbine blades are closer to the ground; common birds rarely fly as high as the blades of Australian turbines;

Wikipedia states that...

"studies show that the number of birds killed by wind turbines is negligible compared to the number that die as a result of other human activities such as traffic, hunting, power lines and high-rise buildings and especially the environmental impacts of using non-clean power sources. For example, in the UK, where there are several hundred turbines, about one bird is killed per turbine per year; 10 million per year are killed by cars alone."

Testimony given by Audubon (the major bird-welfare group based in the USA) to the US Congress is available in the page, Congressional Testimony on Benefits of Wind Power. Basically, Audubon recognise that wind turbines do pose threats to birds, but that Climate Change is a much greater threat and sustainable energy, including well sited wind farms, are needed if the world is to limit the damage done to birds by Climate Change.

Wikipedia also discusses bird impact in its article on the Environmental effects of wind power.

An Australian story; Waubra

"Acciona implements a comprehensive bird monitoring program at the Waubra Wind Farm in accordance with Avifauna Management Plan which was approved by the Minister for Planning in October 2006. This Plan was supported by extensive bird surveys of the site prior to commissioning of the wind farm.

The first year of bird mortality searches at the Waubra Wind Farm were completed in 2010. Dead bird searches are done by two highly trained German Short-haired Pointers and their handler. It is a unique survey method that allows a search of large areas of the wind farm to be done in an efficient and cost-effective manner. The dogs have also proven to have a higher searcher efficiency than people.

There were 28 birds found during the first year of mortality searches. No nationally or state threatened species were impacted. Magpies accounted for 43% of all bird collisions. The extrapolated results for the entire wind farm indicate that 1.65 birds are killed per turbine annually. This can also be presented as 1.1 birds/MW/year.

The mortality rates when compared to wind farms overseas suggest that impacts at Waubra are relatively low. An investigation of 19 wind energy facilities in the USA showed an average rate of 3 birds/MW/year."

Fragmentation of bird habitat

Acknowledgement, John Tsai; his Flickr link.

I have taken the liberty of slightly modifying the text that I received in an attempt to make Tsai's meaning clearer (his English is limited).

"We found that a very direct effect of wind turbines on birds is the disruption of flying path between feeding and roosting sites. That is, the wind turbines cause a habitat fragmentation or a barrier effect. This is sometimes crucial for birds in their energy balance. If they spend too much time avoiding wind turbines or finding a safe way to their roosting sites, they are at higher risk of loosing their optimal habitat use pattern (the shortest route or minimization of energy expenditure).

We have done some research on the interactions between birds and wind turbines, showing that the collision risk might be low, but habitat fragmentation effect significantly high. So, wind turbines should be positioned with regard to bird flight paths.

Bird collision on wind turbines have been reported in many journals and papers; we have not yet found any birds hit. We recently started our research into the construction and operation of wind power and we intend to continue for several years.

I hope the research paper we are writing can be published soon so that more people and decision makers will have better information on which to base wind farm and turbine locating decisions.

Best regards,
Chia-Yang Tsai"

Pygmy bluetongue lizards

The lizards live in spider burrows after either evicting or eating the spiders. Information on the species is available from several pages at Environment SA who state that there are 22 known sites with an estimated population of several hundred lizards living in at least ten of these sites.

Soil disturbance in lizard habitat does destroy lizard burrows and kills lizards. It seems that they do not live much in stony hill-top areas, perhaps because there are few spider burrows in such hard and stony ground. The lizards cannot live in recently ploughed land, and are very slow to re-occupy ploughed land.

Loss of native vegetation

On the whole wind farms will provide more protection to bushland and grassland than cause damage. Climate change is a far greater threat to Australia's native vegetation than is the growth of the wind power industry. The June 2011 issue of Scientific American included a study about fire hazard linked to climate change. It seems that the area burned by wild fires in the US in the average year, given a one degree rise in temperatures, is expected to be up to six times as large as at present, depending on the ecoregion. And bushfires are not the only hazard to native vegetation that comes with climate change.

So we must replace the fossil-fuel fired power stations with renewable energy. Wind power is the most economically viable form of renewable energy at present. Solar has great potential, but requires more development. The potential for hydro power in Australia is quite small, and if we dam rivers to get more hydro that will be much more damaging to the environment than will wind power developments.

Waterloo Wind Farm, South Australia. Many native trees had to be removed for the building of this wind farm. Roaring 40s have an off-set arrangement with the Native Vegetation Council in which $800 000 will be paid toward revegetation and conservation programs.

There is little remnant native vegetation on many wind farm sites; for example I have photos of:

In South Australia...

• Canunda-Lake Bonney
• Brown Hill Range
• Hallett Hill
• Snowtown
• Starfish Hill

• Cape Bridgewater
• Challicum Hills
• Toora
• Waubra

There is more native vegatation at:

• Esperance (WA)
• Mount Millar (SA)
• Waterloo (SA)
• Wattle Point (SA)
• Wonthaggi (Vic)

The proposed Mt Bryan Wind Farm is an interesting case, where damage to native vegetation has been claimed by opponents, but where very little will take place so far as I can tell.

Of course remnant native vegation is valuable and should be retained wherever possible.

General environmental concerns

Roads must be built to gain access to wind turbine sites and 'hard-stands' flattened out where the turbines are to stand; there are environmental problems associated with road building, with the roads themselves and the hard-stands. Roads and road damage outside the area of actual wind farm construction is discussed elsewhere on this page.

• In some areas native vegetation is destroyed;
• Sites of significance to Aborigines can be damaged;
• The existence of a road is a barrier to the natural movement of some native animals;
• Poorly planned or constructed roads in the hilly areas preferred for wind farms can increase erosion potential.

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The question of whether a wind farm can change the local climate is dealt with elsewhere on this page, and I have discussed whether very extensive development of wind power Australia-wide might affect weather on the Wind power potential page.

Roads and road damage

Image credit Warrnambool Standard and Damian White See text for relevance

Dust can be a problem during wind farm construction due to increased traffic movements. The increased traffic itself can also be a problem.

Wind farm opponents commonly complain that the heavy traffic needed to bring in wind farm components damages local roads. Like so many statements from wind farm opponents this is a half-truth. Yes, the additional heavy traffic does damage some of the roads, but I believe that there is also usually an arrangement between the wind farmer and council or between wind farmer and government whereby the wind farmer has to cover the cost of the necessary road repair.

The image on the right was printed in the Warrnambool Standard with the caption "A driver tries to traverse the crumbling Macarthur-Penshurst Road". In fact it is obvious that the driver is intentionally driving in the gutter for the purpose of obtaining a picture with impact. The road shoulder has probably been damaged by heavy wind farm traffic and it would be neccessary for vehicles to move onto the shoulder when passing oncoming traffic, but it is a pity that so much of the media gives a higher priority to impact and sensationalism than truth.

Do environmentalists oppose wind farms?

In fact environmental organisations are strongly in favour of wind power. For example Friends of the Earth, Victoria, have recently (early 2011) started a campaign called 'Yes 2 Renewables' in support of wind power; WWF see wind power as a big part of their 100% renewables by 2050 (The Energy Report, 100% renewable energy by 2050, released in early 2011); Environment Victoria "is a strong supporter of wind technlogy" (from their submission to the Senate inquiry into "The Social and Economical Impact of Rural Windfarms", Australia, 2011); "ACF is generally supportive of wind power (and other forms of clean, renewable energy)" (pers. com.); Gippsland Friends of Future Generations are strongly in favour of wind power.

The opposition is not coming from serious environmentalists who look at the big picture. It is comming from NIMBY (not in my back yard) people, people who simply don't like the look of turbines, and those who are envious of nearby farmers getting big lease payments while they see themselves as getting nothing. Several groups of people have banded together to oppose wind power, but they could not be called environmental groups because their primary, and probably sole, function is the opposition of local wind power development.

Do turbines frighten stock?

Young cattle grazing peacefully beneath wind turbines Toora Wind Farm

Whether there is a period during which stock get used to the turbines I don't know. Having been a dairy farmer for eight years, and having had sheep grazing on my property at Clare for the last 15 years, my own fealing is that neither cattle nor sheep would be much concerned by wind turbines.

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Low lambing rates at Waubra had been attributed to wind turbines (Aug. 2010). When the sheep owner called a vet, the vet said that low lambing rates had been a problem in much of the area recently, whether or not turbines were nearby. I discussed this with a farmer who has a stud sheep business as well as turbines on his property near the Clements Gap Wind Farm; he told me that the sheep like the turbines, resting in their shade in summer, and that he had no problem with falling lambing rates since the turbines were built.

The wind doesn't blow all the time
Wind is intermittent

	The ideal generator of electricity The perfect electricity generating method would cheaply produce a varying amount of power that would exactly match the varying demand with 100% reliability and while producing no pollution. It doesn't exist. (See the pros and cons of various methods of generating electricity.) The inflexibility of coal-fired and nuclear power stations is almost as great a limitation as the pseudo-random variation of wind power generators. All power generators have scheduled interruptions for maintenance and unscheduled breakdowns. Wind power generation graph for August 2007 from Wonthaggi, Victoria Acknowledgement, Wind Power Pty. Ltd. This is a very small wind farm, with only six turbines, so its output is particularly veriable in the short term.
	Power curve of a Suzlon S88, 2.1 MW turbine Data from Suzlon This graph is explained in Wind speed range of turbines, below

Wind can now be forecast fairly reliably 24 to 48 hours ahead. When wind farms are not generating the electricity deficit can be taken up by other generators such as natural gas-fired power stations. Most of the back-up generators only run when required to make up the short-fall in power generation and are idle at other times. Of course there are costs involved in keeping power stations on standby. Some back-up also needs to be kept running as spinning reserve so that it can be brought on-line at very short notice, but this has always been so in case of break-down of generators. In fact, since the variability of power generation from wind farms is slow and predictable it is easier to cope with in a power grid than the occasional breakdown of a large fossil-fuel or nuclear generator, which will be sudden, unpredictable, and produce a big deficit in the power supply-demand balance.

All power stations are off-line some of the time. Fossil-fuelled power stations are typically available around 85% of the time; at other times they are undergoing maintenance or suffering breakdown, etcetera. When they are not generating some other power station must make up the short-fall.

A part of this problem could be overcome by introducing Supply Dependent Load, which is discussed in my Sustainable Electricity page and hydropower could also be used to balance generation and consumption (as is done very effectively with wind power in Denmark balanced by hydropower from Norway).

If it was economically (or environmentally) justified, then additional power supply-and-demand balancing methods could be introduced. I have included a section on how pumped hydro power can be used to balance the generation of wind power on my Sustainable Energy page. Of course developing pumped hydro has its own cost, but power that can be generated on demand and at short notice receives high prices in a supply and demand based power system, so it could prove to be economically justified.

Sometimes too much energy can be generated by wind farms; this could cause overloading problems in the electricity grid. AEMO has the power to make wind farmers limit their generation at such times.

The proportion of electricity that can be generated by wind before problems relating to variability of supply become intolerable has been debated for years. The magazine Wind Power Monthly reported that Denmark generated 31.5% of its power by wind in January 2008 (apparently January is its windiest month) and had generated even more in January 2007 (35.5%). Even more importantly, the article stated that there had been no need to constrain production from the turbines at any time.

When there are many wind farms there is a smooth variation in generation

Power generated from all AEMO monitored wind farms in Australia, 2012/01/15, shown individually
Graphic credit: http://windfarmperformance.info The Y-scale is capacity factor, the X-scale is time in 24-hour notation. Each coloured line records the output of one wind farm.

The graph above shows generation from most of the wind farms in eastern Australia on 2012/01/15. Note that the output of each is quite variable – the lines are jagged. Compare this with the graph below. (2012/01/15 was the most recent full day of data available when this section was added; it was a pretty typical day.)

Power generated from all AEMO monitored wind farms in Australia, 2012/01/15, combined output
Graphic credit: http://windfarmperformance.info The Y-scale is megawatts (MW), the X-scale is time in 24-hour notation.

The graph above shows the combined output from the same wind farms on the same day as in the earlier graph. Note that the output varies only slowly and gradually – the line is much smoother than the lines in the earlier graph. Having a gradually varying output like this, combined with the predictability of wind speed, makes it easy for the grid operator to bring other generators on-line as required.

Sustainable energy must be diversified; we need to develop alternatives such as solar and wave energy as well as wind. When an area is covered by a meteorological high pressure area, and consequently has light winds, there is a good probability that the sun will be shining and solar power output will be high. (See Solar complements wind.)

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A part of the answer to the intermittency of the wind would be to use electricity when it is abundant to desalinate seawater. Australia has major water supply problems; in SA these are particularly severe on Eyre Peninsula (which has excellent wind resources). It should be possible to set up desalination plants to run when there is excess electricity. Electricity can not easily be stored, but water can be, readily and cheaply. Why not have the desalination plants organized so that they switch on when power is abundant and switch off when the power supply declines. Using wind power to desalinate water on Eyre Peninsula is discussed in Eyre Peninsula Water. This and other suggestions for solving the problem of variability of supply of sustainable energy are discussed on my Sustainable Electricity page.

Improved wind forecasting would provide forewarning of changes in the quantity of wind-generated electricity entering the grid.

Wind turbines shut down when the temperature goes above 43 degrees

"Wind generators have a high temperature alarm at around 43 degrees and will shutdown at around 45 degrees to protect components. That's measured at the nacelle 70m above ground. At Challicum Hills (near Ararat) during 2004 our wind farm experienced 15 minutes of unavailability due to high ambient temperature. That's 0.003% of the year."

Temperatures above 43° are rare where wind farms are built, and often occur on calm days when turbines are either not working or working at low capacity.

Bat deaths

Photo borrowed from the Zoonosis Net site

The article stated that most of the bats were common species including red bats, eastern pipestrelles and hoary bats. What was of great concern was the fact that quite probably only a small percentage of the bats killed were being found.

Little research seems to have been done into this potential problem in Australia. I believe that Brett Lane and Associates of Melbourne wrote the wind industry's 'best practice' guidelines on bat and bird monitoring.

Some further information was available at Safewind (link no longer available). This page indicated that the greatest problem is with migratory species, presumably because they fly higher than hunting bats.

Iberdrola Renewables, Acciona, and BP have bat concerns over several USA wind farms that they were intending to develop. It seems that the Indiana bat, an endangered species, has suffered from 'white noise syndrome', and there is concern that wind farms might prove a problem to the species.

Wikipedia discusses bat impact in its article on the Environmental effects of wind power. Wikipedia stated that "In April 2009 the Bats and Wind Energy Cooperative released initial study results showing a 73% drop in bat fatalities when wind farm operations are stopped during low wind conditions, when bats are most active." There would be little loss to the turbine operators in stopping the turbines at such times because very little power is generated in low winds; see Wind speed range of turbines.

Death by barotrauma

Honey bee problems?

There are well known problems occurring in the world's honey bees; varoa mites and colony collapse disorder among the more prominent of them. Separating pollination problems, or bee number reduction problems caused by wind turbines, from these much better researched and credible problems, would require careful research, and I have not heard that any such research has been done.

Wind farms cause power surges?

I believe that regulations imposed on the operators of wind farms in Australia do not allow major power surges. The wind farm operators have to put in place devices stopping power surges entering the electricity grid.

Can a wind farm change the local climate?

Can wind farms affect rainfall?

A farmer from an area downwind of a proposed large wind farm expressed concern to me that the slowing of the wind might cause greater rainfall at the wind farm and less rain downstream. At first it seemed unlikely to me that any effect would be significant, but on more investigation some interesting points started showing up.

Relief rainfall

When a wind turbine takes energy from the wind flowing through it, it slows that wind down. A bit of thought then shows that for the same volume of air to pass a point in the same time, but at a lower speed, it must take up more space. Putting it another way; if you think of a cylinder of air the diameter of the turbine blades approaching the turbine, then the velocity of the same air slowing as it passes through the turbine, the diameter of the cylinder on the down-wind size has to be bigger because the velocity is lower and the same amount of air per unit time must pass through it. The slow-moving air on the down-wind size of the wind farm will take up more space than the higher-speed wind would have before the wind farm was built, so this will cause the air-mass above to rise a little higher to pass over the obstruction.

In Australia, I suspect that most people will think that a slightly increased local rainfall is a very good thing. On the other hand, it would mean that there would be a little less moisture in the air that moves away from the wind farm into other areas.

How much will a wind farm increase the effective height of a ridge?

An example case The Clare 'Valley', an elevated area in Mid North South Australia famous for its high quality wines receives significantly higher rainfall than the surrounding, lower, areas. Roughly, the Clare Valley gets about 600mm annual average while the lower country gets around 400mm. The higher ridges around the Clare Valley are 470m to 550m in altitude. Snowtown wind farm is built on the top of the north-south trending Barunga Range which is roughly 50km to the west of Clare. The top of the Barunga Range is around 325m. Most of the rainfall in the Clare Valley comes from the west; that is, quite a bit of it passes over the Barunga Range. If the wind farm has caused the effective altitude of the Barunga Range to increase from 325m to 345m it would seem likely that this will cause a little more rain near the Barunga Range with correspondingly less remaining for the Clare Valley. (From being about 65% as high as the Clare ranges, the Barunga Range has effectively gone to 69% as high.) To calculate very roughly what this might mean to the local rainfall we can make some very simple assumptions and employ a little basic arithmetic. Supposing that there is a linear function relating rainfall to altitude in the Clare region. We know that rainfall is about 400mm at 100m altitude (the plain between the Barunga Range and the Clare Valley) and is 600mm at 400m (typical of the Clare 'Valley'). Then we can derive an equation: rainfall = 0.667 × altitude + 333; the slope of the function being 0.667. So an increase in the effective altitude of the Barunga Range of 20m should result in a increase in local rainfall of around 0.667×20=13mm per annum.

Research into the significance of this effect would be useful.

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Can wind farms affect temperatures?

It is also a possible that turbulence from wind turbines could cause changes in the local temperatures.

These questions deserve research.

Turbines increase the 'surface roughness' of the land

An array of turbines will have an effect on wind flow similar to that of trees, they will slow the wind at lower levels due to the energy that they take from it and the turbulence that they cause.

In many parts of the world trees and forests have been cleared from huge areas; Australia has lost a very large proportion of the scrub, woodland and forest that it once had in its agricultural areas. Will the introduction of wind farms change the 'surface roughness' back to nearer what it was before the trees were cleared?

Again, research into the likely effects on weather should be carried out.

Links/research on wind turbines and weather

Pim Rooijmans, of Utrecht University, did a master's thesis on the "Impact of a large-scale offshore wind farm on meteorology"; a 3MB pdf file was availble, but no longer is. Rooijmans wrote of a reduction in rainfall in one rainfall event in one place, of more than 50%, but increased rainfall elsewhere. Rooijmans' figures were based on computer modelling rather than actual events.

"Weather response to management of a large wind turbine array" by D.B. Barrie and D.B. Kirk-Davidoff (3.4MB) can be downloaded at www.atmos-chem-phys-discuss.net/9/2917/2009/acpd-9-2917-2009-print.pdf. It discusses modelling of the effect of a continent-scale wind farm on US weather.

Turbulence from wind turbines

Image of turbines at the Danish Horns Rev offshore wind farm; kind permission of Thomas Bak. "Unique meteorological conditions on 12 February 2008 at 1300 hours resulted in the wind turbines creating condensation (i.e. clouds) of the very humid air, thus making it possible to see the turbulence pattern behind the wind turbines." I'm told that this is a pretty legendary photo throughout the wind farm industry, a great example of the need to site turbines so the prevailing wind is not blocked by the turbine in front. Buildings, trees and hills would have a similar effect I have seen this photo used to 'prove' that turbines produce turbulence that could be deadly to light aircraft and would seriously interfear with crop spraying. Lamina flowing wind, as on the upwind side of these turbines, is probably uncommon on land, especially land that has trees and hills. Turbulent winds, probably similar to those on the downstream side of these turbines, are very common over land. Unique photo There seem to be no photos similar to this on the Internet. This fact strongly suggests that the conditions under which this photo was taken, a lamila (smoothly flowing) wind with a very low sea mist and wind turbines, must be very rare.

The New York Times published an article that discussed research published in The Journal of Geophysical Research; lead author, Dr. Somnath Baidya Roy. These researchers, using simulations, found that:

"In the Great Plains [of the USA] there is a nighttime stream of fast-moving air that separates cool, moist air near the ground from drier, warmer air above. The simulation found that the [hypothetical] turbines catch this nocturnal jet, and the ensuing turbulence causes vertical mixing."

The researchers said that:

"During the day, the effects from the disturbed airflow are negligible, since natural turbulence mixes the lower layers of the atmosphere. But the researchers found that in the predawn hours, when the atmosphere is less turbulent, a large windmill array could influence the local climate, raising temperatures by about 2 degrees Celsius for several hours. The rotating blades could also redirect high-speed winds down to the Earth's surface, boosting evaporation of soil moisture."

Turbine wake plumes and aircraft movements

An anti-wind farm speaker at a meeting I attended used the above photo to suggest that wind turbines could kill birds by barotrauma at large distances from the blades; an absolutely ludicrous claim. Apart from the fact that birds are less susceptible to barotrauma than bats, even bats are only affected when very close to the blades, and there is no reason to believe that the turbulence in the photo is at all violent.

The energy consumed in construction of a wind farm is very much less than the energy that farm will produce

A calculation of the embodied energy in the steel of a turbine tower From the Victoria University of Wellington, NZ, page on embodied energies we have the starting point that the embodied energy in virgin (not recycled) steel is 251 200 MJ/m3. Taking the diameter of the tower as 3m, the height as 80m and the wall thickness as 40mm (0.04m) we can calculate that it contains 30 m3 of steel, giving an embodied energy of 7 576 GJ. The rated power of the turbine is 2.1 MW and the capacity factor from my page on wind power in Australia is 34% giving an average generation of 0.714 MW achieved. From my page on energy units we have 1 MJ = 0.278 kWh; (therefore 1 GJ = 0.278 MWh). Based on these figures it is simple to calculate that the embodied energy in this tower would be recovered in 122 days of turbine operation; about four months. I would think that the greatest part of the embodied energy in a wind farm would be in the steel of the towers.

The journal Renewable Energy (20 [2000] 279-288), published a paper by L. Schleisner, titled 'Life cycle assessment of a wind farm and related externalities'. Schleisner discusses two hypothetical wind farms, one offshore and one land-based. He concluded that the energy pay-back time for the offshore wind farm would be 0.39 years and for the land-based wind farm 0.26 years; both being less than 2% of the assumed 20-year lifetime of the wind farms. The journal Renewable Energy has an impact factor of 2.2.

The Danish wind turbine manufacturer Vestas report in a "Lifecycle Assessment of a V90-3.0 MW onshore wind turbine" that it will typically 'pay back' the energy consumed in the whole life of the turbine in 6.6 months.

Suzlon, another wind turbine manufacturer, estimated in regard to the Brown Hill Range Wind Farm in SA that 'the payback period of "embodied energy" of the whole wind farm is approximately 5 months'.

The technical term for the amount of energy consumed in the process of obtaining energy compared to the energy obtained is Energy Return on Investment (EROI) and I have covered this in some detail in Wind power. In the studdy discussed there, wind farms, on average, produce around 18 times as much energy as is used in their construction. One would expect that this figure will increase as wind farms operate for longer periods and as the technologies mature; indeed, given an energy payback period of six months and a (conservative) turbine life of 20 years one can calculate an EROI of 40 (neglecting any energy involved in repairs and maintenance).

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Pacific Hydro state in a publication that "on average it takes only two to three months for a wind turbine to recover all the energy required to build it".

A publication of Wind Energy (Denmark) dated December 1997 states that the energy payback time for a 600 kW turbine is 3.1 to 3.8 months.

The related question of the carbon dioxide balance of wind farms is covered on this page in CO2 and wind farms.

Is the carbon dioxide released in wind farm construction comparable to the amount that will be saved by using wind power rather than some form of fossil fuel?

Also see CO2 and wind farms, which deals with the total amount of carbon dioxide released from wind farm construction, elsewhere on this page.

I have looked into this question in some depth because a friend was concerned by it.

Joseph Davidovits, Geopolymer Institute, Saint-Quentin, France states:

"Studies have shown that one ton of carbon dioxide gas is released into the atmosphere for every ton of Portland cement which is made anywhere in the world."

From McCaffrey "The Cement Industry's Role in Climate Change" (the link, http://www.propubs.com/climate/climate.html, is no longer working), one can calculate that for each tonne of cement that is manufactured, about 0.9 tonnes of carbon dioxide is released into the atmosphere.

The Information Unit on Climate Change, Switzerland, states that about a half a tonne of carbon dioxide is released from the roasting of the raw materials for each one tonne of cement manufactured. This does not include the carbon dioxide released from burning fuel.

Placing the bottom section of a wind turbine tower on its concrete footing

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How much CO₂ is released for each wind turbine?

Pacific Hydro state that the CO₂ abatement due to the power production of each of their 1.5 MW turbines is 5000 tonnes per year (13.7 tonnes per day). My calculations confirm those of Pacific Hydro.

Carbon dioxide released per MWh of coal-generated electricity Figures from The Australian Greenhouse office are that the current best efficiency for brown coal-fired power stations in Australia is 1220 kg CO2/MWh of sent out electricity, and for black coal 861 kg CO2/MWh.

Working on a round figure of 1 tonne of CO₂/MWh for coal-fired electricity generation and a 35% load factor for a 1.5 MW wind turbine we can calculate

• The actual (or average) power generated by a 1.5 MW turbine would be about 0.53 MW.
• CO₂ abatement for this turbine would then be 0.53 tonnes per hour.
• This equals 12.6 tonnes per day or 4600 tonnes per year; very close to the Pacific Hydro figure above.

Conclusion

Since doing the above calculations I have been informed (May 2007) by Peter Reed of Suzlon (Australia) that while 216 tonnes of concrete is sufficient for the footings of the Suzlon 2.1 MW turbines being constructed at Hallett Wind Farm (where they are able to use rock anchors), 800 tonnes of concrete would be required for a 'gravity footing' for the same turbine. I believe this would be used where the turbine was to be constructed in an unconsolidated sediment foundation. Less than a week of operation would be required to 'pay back' the CO2 released from the manufacture of the approximately 80 tonnes of cement in these 800 tonne footings.

Do wind farms really save carbon dioxide emissions?

The Australian Energy Market Operator (AEMO) in it draft 2011 South Australian Supply and Demand Outlook report showed that emissions from electricity generation in SA declined by about 20% over the same period as generation by wind farms increased from near zero to 20% of total generation. See their graph.

Carbon intensity of various electricity generating methods Method g CO2e/kWh Biomass 14-41 Coal 960 Hydro 10 Nuclear 66 On-shore Wind 10 From Sovacool, B.K. Valuing the greenhouse gas emissions from nuclear power: A critical survey. 2008. Energy Policy; 36: 2940-53. Oil fired electricity generation has a carbon intensity about half that of coal, gas fired is a very little better than oil. Brown coal is worse than black coal.

The Australia Institute is an independent public policy research centre funded by grants from philanthropic trusts, memberships and commissioned research. It has a pdf document about The facts and fallacies of wind power. In this document The Australia Institute's researchers state that taking into consideration all the CO₂ released during manufacture, construction and management of a wind farm, every megawatt-hour (MWh) of wind farm electricity comes with a carbon cost of 14kg of CO₂ while coal-fired electricity comes with a carbon cost of around one tonne of CO₂ per MWh.

They further state that:

"the emissions related to the manufacture, construction and operation of the wind farm are likely to be equal to less than two per cent of the emission reductions that arise as a result of the displacement of fossil fuel-based electricity generation."

How much CO2 does wind power save?

Three scenarios were modelled:

• No additional wind generation capacity in Victoria (apart from that already installed)
• 100 MW of additional wind generation, with the average capacity factor of the additional generation being 35%.
• 1000 MW of additional wind generation, with the average capacity factor of the additional generation being 33%.

Average abatement intensity from wind generation, kt CO2e/GWh
Wind Capacity	2007	2008	2009	2010	2011	2012	2013	2014	2015
100 MW	0.95	0.92	0.94	0.93	0.95	0.95	0.93	0.91	0.88
1000 MW	1.12	1.10	1.08	1.09	1.09	1.10	1.05	1.03	1.06

Put simply, in the Victorian situation, for every MWh of power generated by a wind turbine about a tonne less CO2 will be released into the atmosphere than would be without the wind power. See the McLennan Magasanik report for a full explanation.

A single, typical 2 MW wind turbine operating at a typical capacity factor of 35% will generate around 6 000 MWh each year and save about 6 000 tonnes of CO₂ from entering the atmosphere each year. A typical wind farm of 30 turbines will save 180 000 tonnes of CO₂ each year.

Visual objections to wind farms

Clements Gap Wind Farm

Almost everyone, it seems, agrees that there are some places – particularly areas of great natural beauty – where wind turbines should not be built. I can't imagine that anyone would suggest that a row of wind turbines on top of the Wilpena Pound Range in the Flinders Ranges would be desirable.

How we perceive wind turbines visually depends in part on whether we believe that they are, in themselves, desirable and useful. Those who see turbines as a part of the answer to the greenhouse/climate change problem are more likely to consider them beautiful, those who think wind-generated electricity is over-rated or that either climate change is not happening or is not due to Man's activities are more likely to see turbines as intrusive and ugly.

In an article about the proposed Merredin Wind Farm the Merredin Mercury printed the following:

In a study in Geographical Research published by Wiley-Blackwell, it was found wind farms have a negative impact on landscapes with a high scenic quality, but a positive effect on dull and mundane landscapes. Author Dr. Andrew Lothian said while people may be apathetic to the appearance of wind farms, their location is critical. "Wind farms in scenic areas, particularly the coastal areas, are regarded as damaging to the landscape," he said. "However, in agricultural areas of low scenic quality, wind farms seem to beautify the otherwise mediocre surroundings."

Also see Air navigation lights, below.

Air navigation lights

In Denmark and New Zealand lights on wind turbines are one hundredth the brightness of many of those used on Australian turbines.

Lights on or off? In mid January 2010 I noticed that I can no longer see the lights of both Hallett wind farms from my place at Clare. Those on Brown Hill Range Wind Farm were the first to go, followed by Hallett Hill. It seems that AGL has decided that they are no longer needed because the towers are below the minimum legal flighing altitude. I was informed that Trust Power were likely to turn the lights of Snowtown wind farm off in the near future, but as of 2011/01/29 this has not happened. In August 2010 the flashing lights were also still operating at Clements Gap wind farm, but they were off by the end of the year. I visited Wattle Point Wind Farm in late September 2010 and noticed that there were no lights.

The air-navigation lights on the first two of the Hallett wind farms, 50 kilometres away from my place in the Clare hills, were not only visible to me, they were conspicuous (photo above). If I walked about 1km west I could, and can still, see another line of red flashing lights, this time of the Snowtown Wind Farm, 40km away. (The lights of Snowtown Wind Farm are also conspicuous from Crystal Brook, about 40km to the north.) Whether an individual finds the lights objectionable or not is a matter of that individual's perception.

In Australia the Civil Air Safety Authority (CASA) decides how bright the lights must be when the turbines are in the vicinity (approximately 30km) of an aerodrome.

"CASA cannot mandate the lighting or marking of structures outside the vicinity of aerodromes. It is CASA's view that this is a decision for, and the responsibility of, the developer" (pers com Paul Trotman, CASA)."

"Mr Byron (Chief Executive Officer, CASA) has ... directed that CASA now undertake an appropriate safety study into the risk to aviation posed by wind farms and develop a new set of guidelines."

There is no air safety necessity for the lights to be so bright that they are conspicuous at 50km. Being easy to see from 5km would be quite enough for air safety; using the inverse-square law of illumination this would require only one hundredth the present brightness in the lights. Indeed, I have been informed that while CASA advised the use of lights of 2000 candella on tall wind turbines in Australia, the New Zealand authority holds that lights of 20 candella are acceptable at Tararua III Wind Farm, even near an airfield (Terry Teoh, Pacific Hydro, pers. com. Sept. 2008).

In Denmark 10 candella lights are used, and in Germany there are various standards, but usually blinking 100 candella lights are used. (Tobias Geiger, Westwind Energy, Global Windpower conference, Adelaide 2006)

The wind farmers must take the bulk of the blame for the bright lights. As stated above, CASA only has an advisory roll, the wind farmers could use dimmer lights without breaking any law. One can only suppose that they use very bright lights because they fear that if they used anything dimmer and there was an airial acident, they might be sued. They don't want to take any risks with their money. If the lights annoy people, that is of less concern than the remote chance of a big law suit.

If the lights must be bright for those times when visibility is poorer, then there could be two sets of lights, one for good visibility and one for poor – with an automatic system detecting poor visibility and switching from one to the other. At least in South Australia the dimmer lights would be sufficient more than 95% of the time.

Excessively bright lights on wind turbines conspicuously contradict the need to minimise energy consumption. Having obvious wastage of energy, even if it is trivial in comparison to the total energy generated, associated with devices that are aimed at reducing greenhouse gas production seems particularly incongruous.

Water requirement of wind farms

During construction, water is required for making the concrete needed for the footings of the towers, and for things like damping-down while road-building, but these require small amounts of water relative to those used for mining coal or uranium or cooling coal-fired, or nuclear, power stations.

Terry Teoh of Pacific Hydro informed me that in building their last three wind farms (totalling 159 MW installed) they used 36ML of water. Tim Knill of AGL estimated rather less water requirement; my own estimate was similar to Terry Teoh's figure.

For comparison I believe that a typical Australian wet-cooled coal-fired power station uses around 1.5 kL per MWh of electricity generated. The 159 MW of wind farm referred to by T. Teoh above generates about 322 GWhr of electricity per year. That amount of electricity generated by a wet-cooled coal-fired power station would require about 480ML of water. That is about 13 times as much water, every year, as was used to build the Pacific Hydro wind farms.

Comparing with agriculture might also be interesting. The average water consumption for wine-grape growing in the Murrumbidgee Irrigation Area (MIA) is 5ML/ha/year; in the Clare Valley, about 1ML/ha/year. So a single 36ha vineyard in the Clare Valley would use as much water, each year, as was used to build the Pacific Hydro wind farms. In the MIA, 36ML would only be enough for 7.2ha for one year, probably not a big enough vineyard to provide a living for a single family.

One of the greatest advantages of wind power is its very small water requirement.

Do wind farms turn away tourists?

"The small scale of the research undertaken to date, the geographical specificity of each survey commissioned and the variable research methodologies employed has resulted in a fragmented research base that has left planning inspectors unable to reach a definitive conclusion on this subject."

Land values and wind farms

"This study investigated eight wind farms across varying land uses (rural, rural residential, residential) using conventional property valuation analysis. Two wind farms were selected in NSW and six in Victoria. The main finding was that the wind farms do not appear to have negatively affected property values in most cases. Forty of the 45 sales investigated did not show any reductions in value. Five properties were found to have lower than expected sale prices (based on a statistical analysis)."

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Overseas studies generally indicate no adverse effect of wind farms on land values. For example, the US Department of Energy did a $500k study that concluded that there was no evidence property values near wind farms were "consistently, measurably, and significantly affected by either the view of wind facilities or the distance of the home to those facilities." A Lawrence Berkeley press release quoted the study's author, consultant Ben Hoen, "Neither the view of wind energy facilities nor the distance of the homes to those facilities was found to have any consistent, measurable, and significant effect on the selling prices of nearby homes." (The above paragraph was adapted from an article in Powerblog by Kennedy Maize.)

The UK Centre for Sustainable Energy published a document Common concerns about wind power that included a section on "Wind turbines and property prices". It spoke of an "anticipation stigma" regarding adverse effects on land prices that exists during the planning and construction of wind farms, but said that "a great deal of research in the UK and abroad shows that there is no devaluation in property prices nearby once a wind farm is operating".

In the Australian case and concerning the land on which the turbines are built; turbines are usually on the tops of hills where the land is too steep to crop, so no cropping land is usually lost. Stock quickly get used to turbines and will happily graze right under them. The value of a property is dependent on its earning potential and having turbines on a property greatly increases earning potential. The licensing fee normally paid by turbine operators to land owners varies from at least $4000 per turbine per year up to $10 000 at (Dalby, Queensland) and possibly as high as $14 000. (See also elsewhere). So fairly obviously values of land having turbines on it are likely to increase.

The Clean Energy Council provides a fact sheet on wind farms and land values.

At least some people in the real estate business believe that land values decline in the vicinity of wind farms. This is interesting, in that it is contrary to studies such as those mentioned above. It may be associated with the "anticipation stigma" mentioned above.

Photo acknowledgment – treedork, Flickr

Wind turbine litter

The photo at the right is of the Kamaoa Wind Farm, Hawaii. I have no information on the length of time that the turbines remained in a neglected state.

We in Australia must take care that old, unviable wind turbines do not become a blot on the Australian landscape. The owner of the wind farm should be made to remove it when it is no longer operating. Government has a responsibility to make sure that this will be done; perhaps there should be money compulsorily held in trust accounts specifically for the dismantling of wind turbines at the end of their useful lives?

The very large wind turbines that have been used in Australia will have a high scrap value and therefore I would expect that it will be worth dismantling them for their steel, copper and other valuable components, rather than leaving them once they become unusable.

No country anywhere in the world has abandoned wind power, most of those with good wind resources are building more wind farms

The wind farms that are being abandoned are old ones, with old, out-dated turbines. Wind turbine technology has been steadily improving over the past few decades; the best turbines of twenty years ago cannot compete with modern turbines. Why keep a wind farm with out-of-date and (by modern standards) inefficient technology going when there are more efficient options?

In Esperance, WA for example, small, old, out-dated turbines have been replaced with bigger, newer ones; the capacity of the new wind farms (5600 kW) is much greater than the old one (360 kW). It's called progress!

No country that has a significant development of wind power is abandoning wind power; they are all building far more new wind power station capacity than the old that they are abandoning. Total installed wind power world-wide is increasing at an exponential rate.

Lack of transmission lines

In South Australia, for example, southern Eyre and Yorke Peninsulas, Kangaroo Island and the Limestone Coast (south-eastern SA) would have more wind farm development if the existing transmission lines had more capacity. This problem is discussed in greater depth in Sustainable energy in Australia.

The Electricity Supply Industry Planning Council Annual report for 2009 stated that "Further development of wind in South Australia will require significant investment in networks that, at times, already struggle to cope with the transfer of high levels of wind energy, particularly in the mid-north and south-east of the State."

Governments fund and build transmission lines for coal-fired power stations and mines, but no Australian government has yet funded and built a transmission line for sustainable electricity. (Yet another indication that Australian governments are not serious about developing sustainable energy?)

Christeen Milne, Greens MLC in Tasmania, has suggested that wind power development regions (WPDR) should be identified and transmission lines built to these in anticipation of wind farm development. This would replace the present ad-hock industry growth. The US state of Texas is following a similar approach. Among other qualities required for an area to be classed as a WPDR would be for the local people to be generally in favour of wind development.

The only promissing sign (as of November 2010) seems to be the Eyre Peninsula Wind Project, a proposal to build major power lines on South Australia's Eyre Peninsula to connect to major wind resource areas.

Do wind farms replace coal-generated electricity?

The main reason that coal-fired power stations stay in service is that the power consumption in Australia is increasing faster than wind farms are being built. Consider, for example, how popular big plasma TV sets are; they can consume as much power as a refrigerator. Air conditioning too, is a big electricity consumer, and is becoming more common, at least partly driven by rising temperatures due to climate change (which, of course, is driven largely by burning fossil fuels).

Wind farms have not replaced coal-fired power stations, but they may have avoided the necessity of building new ones and they have allowed coal-fired power stations to work at lower rates of production than they would otherwise have done. Wind farms result in less CO2 being released into the atmosphere than would be the case if they were replaced by fossil fuel power generators.

Also see Do wind farms really save carbon dioxide emissions?

How much electricity do wind farms generate?

Wind energy contribution to total SA power generation to mid-2011 Figure from the Australian Energy Market Operator (AEMO) 2011 draft 2011 SA Supply and Demand Outlook report

In fact the typical utility-scale wind turbine seen in Australia today has the capacity to generate up to about two megawatts, and on average will generate about 35% of that (see capacity factor, on another page). The capacity factors achieved in a number of South Australian wind farms is shown on another page.

The graph, from the Australian Energy Market Operator (AEMO) 2011 draft 2011 SA Supply and Demand Outlook report, shows that 20% of SA's electricity came from wind farms in 2010/11. Note also on the graph wind energy is growing quickly. The same report stated that SA's greenhouse gasses due to electricity generation decreased by about 20% over the same period.

Many of the wind farmers, when announcing a new wind farm, will make a statement about how many homes it will be able to supply with electricity. I have listed some of the numbers used by various companies elsewhere on this site; they vary from 400 to 740 homes supplied per installed megawatt of wind power. These figures seem to assume that the average household electrical consumption is between 470 and 875 Watts; 470 Watts seems to me a little on the low side to be credible. Still, given that an Australian wind farm with an installed capacity of 50 MW would be only moderate in size, even if the average household consumption is 1 kW we can calculate that this moderate-sized wind farm would generate enough electricity to supply more than 17 000 homes.

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Finally, it must be remembered that each megawatt-hour of electricity generated by a wind farm means that one less megawatt-hour need be generated by a fossil-fueled power station.

Also see Does wind power replace coal-fired power?, Power generation of wind farm which gives the actual amount of power generated by a number of wind farms and How does wind power compare to roof-top solar?.

How does wind power compare to roof-top solar?

The average roof-top solar power system in Australia is 2.043 kilowatts (Office of the Renewable Energy Regulator) and will generate about 3.2 megawatt-hours of electricity each year. A typical 2.1 megawatt wind turbine will generate about 6300 megawatt-hours each year, as much as around 2000 roof-top solar power systems!

(The working for these calculations is shown on the right. See the glossary for an explanation of capacity factor.)

So while putting a solar power systems on your roof is a step in the right direction in the fight against climate change, providing support to a wind-power company that wants to build wind turbines would be a much bigger step.

In what range of wind speeds do turbines operate?

Power curve of a Suzlon S88, 2.1 MW turbine Data from Suzlon

There is a wind speed below which a turbine will not rotate and will not generate any electricity; this is the cut-in wind speed. (Up to a wind speed of about 4m/sec. in the graph on the right.)

As the wind becomes stronger than this the turbine generates more and more power until the nominal (or full-power) wind speed is reached. (From 4m/sec. to 14m/sec. in the graph.)

As the wind increases above the nominal speed the turbine continues to generate its maximum power until the wind gets up to the cut-out (or stop wind speed). (From 14m/sec. to 25m/sec. in the graph.)

If the wind speed increases above the cut-out speed the blades are 'feathered' (turned about their axes so as not to produce rotational force at the hub) and the turbine stops. (Above 25m/sec. in the graph.) Winds of greater than 25m/sec. (90km/hr) are very rare in Australia.

Wind turbines generate power from the cut-in wind speed right up to the cut-out wind speed. A graph showing a one month generation record from a wind farm is above. It shows that most of the month that farm was generating some power. The graph was not chosen because it was in any way exceptional.

The amount of wind energy theoretically available is proportional to the cube of the wind speed.

Lightning strike

Lightning strike on a wind turbine at Hallett, South Australia Photo credit Helen Simpson, Osprey Photography

The turbine in the photograph is at Hallett in Mid North South Australia. There was no damage to the turbine; there rarely is. There probably were a number of other strikes on Hallett turbines on the same night.

Interestingly, while a lightning strike on a grassy hill-top might well start a grass fire, if that hill is protected by a row of turbines the fire risk would be greatly reduced. Instead of being able to start a fire by striking the ground the lightning that strikes a wind turbine will be conducted safely to the earth.

I wonder if there will be less fires because of wind turbines. I would think it quite probable.

Aesthetics

Interestingly, I don't think anyone likes the look of a line of power pylons. Wind farm construction requires the construction of a transmission line to take the power from the wind farm to the nearest point at which it can be fed into the main power grid.

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Roads have to be built to give access to the turbines for construction and maintenance. An old curving country road can be attractive, a new road very rarely is.

Trees and other native vegetation have been removed from some ridges to allow the building of turbines and the access roads. At one time many Australians would have thought the removal of trees from land a step forward and an improvement, but I think that time is long past; most Australians now would prefer that trees be left in place.

Secret deals

Do wind farm companies make secret deals with people?

Wind farm companies have to come to agreements with land-owners about the use of land for the wind farm turbines. If any particular land-owner knew what the other land-owners were being offerred then he would have an advantage in his negotiations with the wind farmers.

Similarly, if a wind farm company has to buy-out the house of someone who has a problem with turbine noise, they do not want the details of the deal known to everyone. They may have to buy-out someone else later on, and knowing the details of any previous buy-out would give the person selling an advantage.

It is normal business practice to try to minimise costs, so the wind farmers make their agreements with land-holders confidential. No-one is being forced into making a secret deal; all parties have the right to agree or disagree to any particular offer, and to make other offers.

All this having been said, if the wind farmers hope to win the trust of the communities in which they are intending to develop their projects, they should minimise secrecy. Everyone knows that there is some secrecy/confidentiality, but by its very nature, no-one can know how much there is. Secrecy often leads to mistrust.

Self-inflicted problems

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They complained of friction with neighbours who had signed such agreements and of their costs, time and trouble opposing the wind farm proposal. They complained of the (anticipated) reduction in the value of their land and of receiving no benefit from the wind farm.

Had they agreed to have the turbines on their land then there would be no cause for friction with their neighbours who also had turbines, they would not have incurred any costs in opposing the development, their land value would have increased because of the increased income it generated, and they would have benefited from the development.

Denmark and wind power

Wind farm opponents have said that Denmark is shutting-down wind farms because they don't work; this is quite false, Denmark continues to build more wind farms (many off the coast because of limited available land space – it is a densely populated country).

Denmark routinely produces more than 20% of its electricity from wind and has generated over 30% in a few months. There are plans to increase the share of wind power in Denmark up to 40%. It does power-share with Norway, a nearby country that has a lot of hydro-power.

In May of 2011 I was told that Denmark is to stop building wind turbines onshore and will only build offshore in future. I had an email from Karina Lindvig of the Danish Wind Energy Association stating that "there is absolutely no truth to that story".

A survey of over 16 000 Europeans by Eurobarometer conducted from February to April of 2002 found that "Denmark, Netherlands and Sweden place the most faith in renewables".

Too many turbines

I would suggest that this in not a fault of the turbines or those who build the turbines, but an indictment of our greed for cheap and plentiful energy. So long as we want more and more energy it has to come from somewhere, and wind turbines are less damaging than most of the alternatives.

Wind farms have high approval in the general community, but are less popular locally

There are real concerns that people may have should a wind farm be built near them, many are discussed on this page, so I won't list them here.

Farmers who are to have turbines built on their land, and receive lease payments for the use of that land (several thousand dollars per turbine per year) are, understandably, generally strongly in favour. A householder who is going to have several turbines built a few kilometres from his or her house and get little direct financial benefit is usually quite understandably less enthusiastic.

It is becoming clear that, if local opposition to wind power is not to overwhelm general approval, there needs to be more reward for those people who host turbines in their vicinity, but do not currently receive any income from them. How this might be done, beyond the Community funding that often comes with wind farms, is not an easy question to answer.

And who should pay for it? Wind farms benefit the whole population by increasing the amount of renewable energy available; so should some compensation be paid out of taxation revenues? It would seem simpler and preferable if it were left to the wind farm operators, but care must be taken to not kill the goose that lays the golden egg.

Safety

Graph credit UK Centre for Sustainable Energy

"Taking figures from the start of the commercial wind energy industry in 1975 up to 2010, there have been 44 recorded fatalities (this includes a technician who reportedly committed suicide by hanging), an average of 0.054 deaths/GWey. Conventional fossil fuel industries have considerably higher rates, ranging from 0.197/GWey for natural gas, to 6.921/GWey for coal and 15.058/GWey for liquified petroleum gas. The outlier is nuclear energy, with just 0.048 deaths/GWey due to accidents – although it should be remembered that the hazards associated with nuclear energy are much greater in the event that something goes wrong, with 'latent mortality' difficult to quantify."

The Australian Energy Market Commission's report on "Future Possible Retail Electricity Movements: 1 July 2010 to 30 June 2013" stated in its Executive Summary that "the most significant driver of the expected increase in residential electricity prices is the increasing cost of distribution services, which is expected to contribute 41% of the total increase in residential electricity prices". Other substantial increases were ascribed to wholesaling (19%), transmission (8%) and retailing (14%).

On the other hand: "Renewable Energy Target (RET) costs are forecast to comprise around 11% of the total increase in residential electricity prices at a national level. This increase in costs is related to an expansion in the renewable energy generation target from the Mandatory Renewable Energy Target of 9,500 GWh to the RET of 45,000 GWh by 2020. Other components of the residential electricity price include feed in tariff scheme costs and the costs of other state based energy efficiency and demand management schemes. Together these cost components comprise around 5% of residential electricity prices at a national level and are not expected to have a significant impact on the total residential electricity price over the reporting period in most jurisdictions."

No wind turbines damaged in major 2011 Tohoku Japanese earthquake

"Colleagues and I have been directly corresponding with Yoshinori Ueda leader of the International Committee of the Japan Wind Power Association & Japan Wind Energy Association, and according to Ueda there has been no wind facility damage reported by any association members, from either the earthquake or the tsunami. Even the Kamisu semi-offshore wind farm, located about 300km from the epicenter of the quake, survived. Its anti-earthquake "battle proof design" came through with flying colors."

Also see the Wikipedia article.

Collision with turbines is an obvious risk, but would seem to be easily avoided, just as collision with power lines is avoided. However, turbines do cause turbulence that could impact on aircraft safety.

The Directorate of Airspace Policy of the UK Civil Aircraft Authority (CAA) produced a guidelines document on wind turbines. While the document did not give anything definitive on turbulence, it did say:

"There is evidence of considerable research activity on modelling and studying the wake characteristics within wind developments, using computational fluid dynamics techniques, wind tunnel tests and on site lidar measurements. A thorough literature survey would be necessary to establish the scale and the advances of the research findings."

and:

"... the CAA has received anecdotal reports of aircraft encounters with wind turbine wakes representing a wide variety of views as to the significance of the turbulence. Although research on wind turbine wakes has been carried out, the effects of these wakes on aircraft are not yet known. Furthermore, the CAA is not aware of any formal flight trials to investigate wake effects behind operating wind turbines."

I have not been able to find much credible information on this matter. I'd be pleased to hear from anyone who knows of any. On 2012/02/01 I emailed the Civil Air Safety Authority of Australia (CASA) inquiring about light aircraft and wind turbines.

Importantly, while there are tens of thousands of utility scale turbines in the world, there has apparently never been an aircraft accident due to the turbulence on their down-stream side.

Wind power problems, alleged problems and objections: links

The Australia Institute is an independent public policy research centre funded by grants from philanthropic trusts, memberships and commissioned research. It has a 134kB pdf document about The facts and fallacies of wind power.

Another useful document is "Wind Energy: The myths and the facts", from Sustainability Victoria, the full URL of the page is "http://www.sustainability.vic.gov.au/www/html/ 2148-wind-energy-myths-and-facts.asp".

The Clean Energy Council also provide fact sheets on wind farms, but they could hardly be called a disinterested party.

The Danish Wind Industry Association has an excellent Guided tour of wind power; this is by far the most detailed explanation of all aspects of wind power that I know of.

Wikipedia has an extensive page on the Environmental effects of wind power.

An expert panel review of "Wind Turbine Sound and Health Effects" conducted for the American Wind Energy Association and the Canadian Wind Energy Association is available from American Wind Energy Association.

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