Wind power problems,
alleged problems and objections

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.

Also see Links, below.

Is wind power the answer to greenhouse and climate change?

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

• Develop other renewable energy sources;
• Reduce wastage of energy and unnecessary energy use;
• 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;
• Walk or ride bicycles more, not only will it save greenhouse gasses, it will improve our health and make our cities more pleasant places in which to live;
• Make our housing less hungry for energy;
• Improve public transport;
• Cut down on unnecessary consumption;
• Cut down on unnecessary packaging;
• Reuse rather than throw away;
• Recycle where we can't reuse.

Are wind turbines noisy?

"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."

It is quite possible to hear the turbines up to distances of, say, 500m given the right wind conditions, but few people could honestly say that they were noisy.

When wind farms are built wind farmers either buy those houses that are close to proposed turbine sites or arrange the sites so that they are at least 400 to 500m from occupied houses.

I have camped overnight beneath the turbines of Starfish Hill wind farm and had no problem at all getting a good night's sleep; the sound of the turbines, if anything, was relaxing.

I visited Toora in late April 2008, staying in the caravan park at the foot of the hill on which the Toora wind farm 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, and then only once in a while.

Do wind farms have health effects?

I can only say that I have never heard of any credible account of wind farms or wind turbines harming anyone's health, and I find it difficult to imagine how they could.

An article in the South Australian press on 2009/08/04 dealt with a study by pediatrician Nina Pierpoint who is reported to have stated that wind turbines "can lead to a greater risk of heart disease, panic attacks and migraines". Her study was criticised for being based on a very small number of people (38) and it seems that it was not printed in any learned journal; it seems to have little scientific validity.

I believe that flashing light can bring on epileptic fits in people who are susceptible to the latter. In places close to turbines – no further than a kilometre or so – for short periods during the day and at particular times of the year, the moving turbine blades can pass in front of the sun and cause the sunlight to flash. This can be annoying, but I have never heard that it caused any harm to epileptics or anyone else.

How close should a turbine be to a house?

The minimum distance that a wind turbine should be from an occupied house is largely a matter of opinion and is therefore difficult to determine.


As always, any informed comments from readers would be very welcome.

Do wind farms cause social conflict?

In the area that I live in (Mid-North South Australia) few people oppose wind farms in themselves; some people are quite reasonably concerned with conserving environment in wind farm areas. I have not heard of any significant social conflict in the region due to wind farm construction.

There are other areas where 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 stakes are high.

Isn't it just as valid to say, rather than "wind farms cause social conflict", "wind farm opponents cause social conflict"? The fact is that any industrial development, especially a conspicuous one, is likely to cause some conflict in some cases.

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; are they mocking the local people?) When I was there, 1100 to about 1330hrs Friday 2009/02/13, there was no sign of life. AGL is particularly poor at answering inquiries.

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. 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 letting down the industry as a whole. They are also holding back the development of the technology to the detrement of the nation's take-up of sustainable energy.

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.

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 has one that is 5MB). HTML can be much more efficient; this page, for example, including images, is about 180kB.

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 oponents 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 is building the Clements Gap wind farm in the Crystal Brook area, consulted widely with the local communities.

Do wind farmers support local communities?

At the present (January 2009) I do not know whether this is true, but have inquired (AGL have not responded to a number of my inquiries).

So far as I know, most wind farmers do support the local community. For example, Pacific Hydro, which is building a wind farm near my home town, Crystal Brook, is to give $50 000 each year for community projects for the life of the wind farm.

Are wind turbines just a short-term source of sustainable energy?

In fact modern (~2009) wind turbines have an expected life span of around 25 years; typical solar photovoltaic panels are guaranteed for twenty years. 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.

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 2.1MW turbine Data from Suzlon

From an environmental point of view, does it matter that wind turbines do not take all or most of the energy from the wind that passes through them? The answer has to be no.

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.

On the other hand, wind is a renewable resource, we can never use it up, and the process of taking energy from it produces no pollution. Also, if a particular turbine takes little energy from the wind that passes through it, the main result is that the velocity of that wind is not much reduced. (The turbine might produce turbulance, this has environmental implications and has been discussed elsewhere on this page).

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 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 2.1MW turbine at a range of wind speeds Data from the table above

The graph at the right shows the efficiency of a typical modern turbine in relative terms, where its highest efficiency (at a wind speed of 8m/sec.) is defined as 1.0 and its efficiencies at other wind velocities are rated relative to that.

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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Wind turbines and television reception

Brendan Ryan of Suzlon has given me some information on this:

"AGL is pretty far down the track in putting a whole new TV tower in the Mid North to cover the reception problems. They are real and have always been the main issue with windfarms. The geography doesn't do any favours either and of course there is a lot of perception associated with TV. If the resident can see strobes across their TV picture, chances are it is due to the windfarms."

"Before we start a windfarm, it is a condition that we or the client take a TV signal strength survey of all houses within approx 10KM. This gives a good base so we can agree/disagree that it is caused by the windfarm. Unfortunately from my experience it also gives the residents a belief that their TV will be affected and every time their reception is bad, 'it is the bloody windfarm.'"

I have made further inquiries.

Is solar power somehow 'better' than wind power?

How should we judge which is 'best'? 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 (although there is still a bias toward the old fossil fuel power generation methods). The people who invest their money in wind farms and the business people running the companies that build wind farms are not stupid.

What are the factors involved?

Operational
Factor	Wind	Solar
Generation at peak demand	Wind power generation is relatively low during periods of peak demand, see Wind Power in SA.	Solar power facilities are usually generating at near their maximum during periods of peak demand.
Environmental
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 2.1MW) can generate about 5.5GWh 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 3MWh 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 000m2 (say 100m by 130m) would be needed to generate the same amount of energy as the 2.1MW 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 the 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. They can be built 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.	Solar power stations can be sited inconspicuously, but must cover very large areas if they are to generate serious power.
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 around the first three 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.	Most large solar 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. For what it is worth, in my opinion wind power seems a little more environmentally benign at present than does 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

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.

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-wellfare 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 the 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.

If readers know of independent scientific studies of bird (and bat) mortality in Australian wind farms I'd love to add some of the results here.

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"

General environmental concerns

Roads must be built to gain access to wind turbine sites; there are environmental problems associated with road building and with the roads themselves.

• In some areas native vegetation is destroyed by the road building;
• Sites of significance to Aborigines can be damaged by road building;
• 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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Dust can be a problem during wind farm construction due to increased traffic movements. The increased traffic itself can be a problem, and the weight of the trucks and cranes can damage roads. (Generally, I believe, agreements are reached between wind farm builders and local councils in which the roads will be suitably maintained or improved at the cost of the wind farm builder.)

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.

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.

I'd be pleased to receive any first-hand information on this question.

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

Wind power generation graph for August 2007 from Wonthaggi, Victoria Acknowledgement, Wind Power Pty. Ltd.

Power curve of a Suzlon 2.1MW turbine Data from Suzlon This graph is explained in Wind speed range of turbines, below

Sometimes too much energy can be generated by wind farms; this could cause overloading problems in the electricity grid. NEMMCO 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 important, the article stated that there had been no need to constrain production from the turbines at any time.

The fact that wind farms are wide spread in Australia helps. If the wind slows in one area chances are that it will still be blowing in other places. Unfortunately much of Australia's wind power is concentrated in south-eastern Australia and if this area is covered with a meteorological high pressure area then much of the country's wind power will not operate. WA is not on the National Power Grid so even if the wind is blowing in WA it is of no help to eastern Australia.

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.

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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. It should be possible to set up desalination plants to run when there is excess electricity. Electricity can not be 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."

It is a pity that turbine manufacturers are apparently not able, or not willing, to modify their designs and build turbines suited to hot climates. If turbines shut down due to heat in the extreme south of South Australia then how workable will they be in the north of Australia or in places like India? This has to be a question of costs. Once the manufacturers realise that there is a need for turbines to run at higher temperatures, and that there will be a market for high temperature tolerant turbines, they will probably change their operations to fill the need.

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 is available at Safewind. 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.

Death by barotrauma

Wind farms cause power surges?

I belive 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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Turbulance from wind turbines

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."

Can wind farms affect temperatures?

It is also a possible that turbulance 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 a similar effect on wind flow, they will slow the wind at lower levels due to the energy that they take from it and the turbulance 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. 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 can be downloaded. 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.

Is the energy consumed in construction of a wind farm comparable to the energy that farm will produce?

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. On average wind farms produce around 18 times as much energy as is used in their construction, and this figure will increase as wind farms operate for longer periods and as the technologies mature.

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

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".

Considering my calculations below on the pay-back time for the CO₂ released in the manufacture of the concrete foundation of a wind turbine, the above statements seem quite reasonable.

A publication of Wind Energy (Denmark) dated December 1997 states that the energy payback time for a 600kW turbine is 3.1 to 3.8 months and Suzlon estimated that the energy payback time for Clement Gap wind farm will be five months.

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 1.5MW 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 1.5MW wind turbine we can calculate

• The actual (or average) power generated by a 1.5MW turbine would be about 0.53MW.
• 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 2.1MW 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?

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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."

I have written about my own investigation into the amount of CO2 released from wind-farm concrete elsewhere.

Visual objections to wind farms

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 one hundredth the brightness of some used in Australia have been used on wind turbines.

The air-navigation lights on the Hallett wind turbines, 50 kilometres away from my place in the Clare hills, are not only visible to me, they are conspicuous (photo above). If I walk about 1km west I can see another line of red flashing lights, this time of the Snowtown wind farm, 40km away. 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 vareous 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.

January 2009

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."

Wind farms and land values

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 significantly increases earning potential. The licensing fee normally paid by turbine operators to land owners is, I believe, around $5000 per turbine per year, I've heard of $7000 on one Victorian wind farm and it can be as high as $10 000 (Dalby, Queensland). So fairly obviously values of land having turbines on it are likely to increase.

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

My own inquiries with people in the real estate business in the Mid North region of SA (Jan. 2009) indicate that the value of land with turbines on it has risen because of the increased earning potential, while there has been no significant change to the value of land near wind farms.

Photo acknowledgment - treedork, Flick

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 failed wind turbines do not become a blot on the Australian landscape.

A comment I can make here is that the very large wind turbines that have been used in Australia will have a high scrap value and therefore it will probably be worth dismantling them rather than leaving them once they become unusable.

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.

Governments build transmission lines for coal-fired power stations, one wonders why they do not for sustainable wind power?

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 is for the local people to be generally in favour of wind development.

Do wind farms replace coal-generated electricity?

The main reason that coal fired power stations stay in service in addition to new wind farms is that the power consumption in Australia continuously increases. Consider, for example, how popular big plasma TV sets are; they can consume as much power as a refrigerator.

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.

How much electricity do wind farms generate?

Wind energy contribution to total SA power generation Figure from 2008 SA ESIPC annual 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.

The graph at the right, from South Australia's Electricity Supply Industry Planning Council, shows that just over 10% of SA's electricity came from wind farms in 2007/08. Note that while wind energy is still a small part of total SA electricity it is by far the fastest growing component.

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 700 homes supplied per installed megawatt of wind power. These figures seem to assume that the average household electrical consumption is between 500 and 875 Watts; which seems to me perhaps a little on the low side. Still, given that an Australian wind farm with an installed capacity of 50MW would be only moderate in size, even if the average household consumption is 1kW we can calculate that this moderate-sized wind farm would generate enough electricity to supply more than 17 000 homes.

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.

In what range of wind speeds do turbines operate?

Power curve of a Suzlon 2.1MW 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 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.

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