Some of your questions may be answered by the Sustainable Development Commission's document "Wind Power in the UK"
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Wind Energy and Environmental Impact
Public Opinion
How do Wind Turbines Work
Wind Farm Economics
Offshore wind farms and other renewable energy sources

1. Are wind turbines noisy?

Thanks to advances in wind turbine technology, well designed, well sited turbines can be quiet enough to cause no disturbance to people living just a few hundred metres away. At these distances, any noise they do make is usually drowned out by the natural noise of the wind itself in the trees and vegetation. To protect nearby residents from any undue disturbance, proposals to install wind turbines are required to meet strict noise standards.

People visiting wind farms are often surprised at how quiet they actually are. The Scottish Executive public opinion survey (Public Attitudes Towards Wind Farms in Scotland) is one of several demonstrating that concerns about noise are often unfounded. Before construction of the Scottish wind farms studied, 12% of people living near the sites thought that the turbines would cause a noise nuisance, but after construction, when people had experience of the wind farm operating, only 1% thought they were noisy.

2. Do wind turbines spoil the landscape?

This is a highly subjective issue. Being visible is not necessarily the same as being intrusive. While some people express concern about the effect wind turbines have on the beauty of our landscape, others see them as elegant and beautiful, or symbols of a better, less polluted future.

The landscape we inhabit is largely human-made and it evolves over time. In comparison to other energy developments like nuclear, coal and gas power stations, or open cast mining, wind farms have relatively little visual impact. Nevertheless sites within Areas of Outstanding Natural Beauty (AONBs) or National Parks are unlikely to be appropriate for large wind farms.

Wind energy is one of the most environmentally benign ways of producing the electricity we need to power our daily lives. If cleaner forms of energy are not adopted, climate change will alter much of our landscape as well as the animal and plant life it contains.

3. Do wind turbines kill lots of birds?

Monitoring of existing wind farms suggests that with sensitive siting there is no adverse effect on bird populations. The Royal Society for the Protection of Birds (RSPB) supports the sustainable development of renewable energy such as wind power because it helps mitigate climate change, which they believe "poses the most significant long-term threat to the environment. The available evidence suggests that appropriately positioned wind farms do not pose a significant hazard for birds."

4. Do wind turbines frighten livestock?

Agricultural land on which turbines are sited can continue to be used for growing crops or grazing livestock. Wind turbines do not disturb sheep, cows or horses.

5. How long does it take for a turbine to 'pay back' the electricity used to manufacture it?

The comparison of energy used in manufacture with the energy produced by a power station is known as the 'energy balance'. It can be expressed in terms of energy 'pay back' time, i.e. as the time needed to generate the equivalent amount of energy used in manufacturing the wind turbine or power station.

The average wind farm in the UK will pay back the energy used in its manufacture within three to five months, and over its lifetime a wind turbine will produce over 30 times more energy than was used in its manufacture. This is quicker than coal or nuclear power stations, which take about six months. When the energy used to supply the fuel for nuclear and coal power plants is included, the energy balance for those conventional source is poorer still.

In 2004 the Department for Trade and Industry (DTI) calculated that onshore wind farms recover around 80 times the input energy required.

6. How safe is wind energy?

Unlike nuclear power, wind farms produce no waste or pollution, and present no danger of meltdown or consequent of terrorist attack.

7. Will building wind turbines help prevent global warming?

Carbon dioxide (CO2) is the most important of the greenhouse gases, which are changing our climate. The UK currently emits 560 million tonnes of CO2 every year. If dangerous levels of climate change are to be avoided CO2 emissions must be reduced by 80-90 per cent by 2050. That means switching to forms of energy generation that do not produce CO2.

Wind power is a clean, renewable form of energy, which during operation produces no carbon dioxide. While some emissions of these gases will take place during the design, manufacture, transport and erection of wind turbines, enough electricity is generated from a wind farm within a few months to totally compensate for these emissions. When wind farms are dismantled (usually after 20-25 years of operation) they do not leave a legacy of pollution for future generations. The site of a wind farm can easily be restored without the potential risk of contamination possible from conventional energy generating sources.

Given the scale of the CO2 cuts needed, wind power - as the cheapest, most developed renewable energy technology, and the fastest to build - is the best placed renewable technology to deliver carbon cuts on a large scale, quickly.

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8. How popular is wind energy?

Wind energy is one of the most popular energy technologies. Opinion surveys regularly show that just over eight out of ten people are in favour of wind energy, and less than one in ten (around 5%) are against it. The rest are undecided.

Some residents may be apprehensive about any proposed local wind developments. When accurate information and knowledge is made available, experience shows that the initial concerns are reduced and support for wind farm schemes increases.

9. Why is there opposition to wind farms?

Local opposition to proposed wind farms usually arises because some people perceive that the development will spoil the view that they are used to. It is true that a large wind farm can be a significant change, but while some people express concern about the effect wind turbines have on the beauty of our landscape, others see them as elegant and beautiful, or symbols of a better, less polluted future.
The increased utilisation of renewable energy and greater use of wind power will mean that we will have more of these structures visible from our townscape and in our landscape in the future.

10. Does wind farming affect tourism?

There is no evidence to suggest that wind farms deter tourists, indeed many wind farms are themselves tourist attractions.

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11. What are wind turbines made of?

The towers of the wind turbines are mostly tubular and made of steel; some are made of concrete. The blades are made of glass fibre reinforced polyester or wood-epoxy. The turbine towers tend to be light grey in colour because this is the colour, which is most inconspicuous under most light conditions. The finish is matt to avoid reflected light.

12. How big are they?

Large modern wind turbines have rotor diametres ranging up to 65 meters. Smaller machines (around 30 metres) are typical in developing countries. Towers range from 25 to 80 metres in height. Offshore turbines generally are at the larger end of the size scale.

13. How does a wind turbine make electricity?

The simplest explanation of how a wind turbine works is that it is exactly the opposite way to a fan. Instead of using electricity to make wind, turbines use the wind to make electricity.

Almost all wind turbines producing electricity consist of rotor blades, which rotate around a horizontal hub. The hub is connected to a gearbox and generator, which are located inside the nacelle. The nacelle is the large part at the top of the tower where all the electrical components are located.

Most wind turbines have three blades, which face into the wind; the wind turns the blades round, this spins the shaft, which connects to a generator and this is where the electricity is made. A generator is a machine that produces electrical energy from mechanical energy, as opposed to an electric motor, which does the opposite!

14. How much electricity does one turbine produce?

The energy produced from a single turbine will vary in relation to its size. It is possible to calculate the number of homes that can be powered by a turbine or wind farm by multiplying the rated MW capacity of the turbine or farm by 696. (The details of the calculation are below)

The offshore wind farms now being built are using turbines of 2MW on average. One of these could provide enough electricity to meet the annual need of around 1400 homes. Offshore proposals in 2004 are for turbines up to 3.6MW.

An offshore wind farm of 660 turbines of 3.6MW in size could replace the UK's biggest nuclear power station at Sizewell. Proposals for wind farms such as the Airtricity farm in the Irish Sea, or Amec's plans for onshore wind in Lewis could, on their own, replace one or more smaller Magnox reactors.

Calculation:

In order to convert the rated capacity of a turbine (given in MW) into power, as in usable KWh/year the following calculation needs to be made:

Rating of turbine (e.g. 2MW) x 24 (hrs in the day) x 365 (days in year) x 0.35 (the capacity factor*) x 1000 (to get into KWh, rather than MWh). This gives the kw/h produced per year per turbine. To find out how many households each turbine can service, divide this total by 4400 (the average kwh used per household per year).

(* 0.35, or 35% is the average capacity of the turbine, as it does not produce at 100% capacity all the time due to weather conditions etc. Some calculations given by developers will use slightly higher or lower capacity factors, depending on whether the turbines are onshore or offshore and wind speeds in that area).

15. How fast do the blades turn?

A turbines blade rotates at anything between 15-50 revolutions per minute at constant speed. An increasing number of machines do however operate at variable speed.

16. Can wind turbines meet all our electricity needs?

Currently wind sourced energy meets less than 1% of the UK's electricity needs. The UK wind resource is enormous. The Department of Trade and Industry (DTI) calculates that onshore wind could theoretically meet 80% of our current electricity demand, and that the offshore wind resource could supply 10 times our needs.

The UK remains close to the bottom of European "league table" in terms of the percentage of electricity consumption met by renewable energy. This is despite the fact that the UK has the largest renewable resources in Europe. Germany has only a quarter of the UK's offshore wind resource, but German plans for offshore wind far outstrip the UK's ambitions and Denmark already generates 20% of its electricity from wind power.

A report "Sea Wind East" in 2002 by AEA technology for Greenpeace - demonstrates that nuclear power's contribution to our electricity needs (currently around a quarter) could be replaced by 2020 by wind farms off the coast of East Anglia. It is however unlikely that our needs will be met by wind power alone, but a balance of renewable sources - including wind, wave, solar and biomass.

17. How much space do wind turbines require?

Wind is a diffuse form of energy, in common with many renewable sources. A typical wind farm of 20 turbines might extend to an area of 1 square kilometer, but only 1% of the land area would be taken out of use, the remainder can be used for other purposes, such as agriculture or as natural habitat.

To obtain 10% of our electricity from the wind would require constructing about 12,000 MW of wind energy capacity. Depending on the size of turbine, they would extent to over 80,000 to 12,000 hectares (0.3%-0. 5% of the UK land area). Less than 1% of this would be used for foundations and access roads, the other 99% could still be used for productive farming. For comparison, between 288,000 to 360,000 hectares (1.2% -1.5% of the UK land area) is covered by roads and some 18.5 million hectares (77%) are used for agriculture.

18. How long do the wind turbines last?

A wind turbine typically lasts around 20-25 years (designed to last 30 years). During this time, some parts may need replacing. At the end of their lives, they can be replaced with newer designs in a few days or fully decommissioned.

19. What happens when the wind farm is decommissioned?

The way that the wind farm will be commissioned will be addressed by conditions attached to the consent given by the Secretary of State under Section 36 of the Electricity Act 1989. These conditions typically require all visible traces of the wind farm to be removed. This will address the long-term impact of the turbines. Service tracks, if there are any, could be removed. Each case is different, depending on the size and the geography of the development.
The concrete bases could be removed, but it may be better to leave them underground, as this would result in fewer disturbances. If the bases are left, peat, stone or other indigenous material could cover them, and the site restored as far as practicable to its original state.
In comparison to the problems associated with the decommissioning of a nuclear power station, or a coal or gas plant, decommissioning a wind farm is straightforward.

20. What wind speed is required to make the wind turbines work?

Wind turbines start operating at wind speeds of 4 to 5 metres per second (around 10 miles an hour - i.e. a "gentle breeze", where leaves and small twigs on trees are in constant motion) and reach maximum power output at around 15 metres/second (around 33 miles per hour - i.e. "strong breeze" to "near gale" - when whole trees are in motion, and it becomes hard to walk against the wind). At very high wind speeds, i.e. gale force winds, (25 metres/second, 50+ miles/hour) wind turbines shut down.

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21. How much does it cost to make electricity from the wind?

Wind energy is one of the cheapest of the renewable technologies. It is competitive with new clean coal fired power stations and cheaper than nuclear power. The cost of wind energy varies according to many factors. An average for a new wind farm in a good location is 2.88 pence per unit. Electricity from smaller wind farms can be more expensive.

22. How much of the time do turbines produce electricity?

The output of a wind turbine depends upon the wind regime where it is located. In the UK the average capacity factor is around 30%. This means that over the course of a year the turbine would produce 30% of the amount it could theoretically have produce if it was working flat out all through the year.

Turbines on average turn, and therefore produce electricity, for about 80 - 85% of the time. Again this depends upon location.

23. Isnt wind generation expensive?

The cost of generating electricity from the wind has fallen dramatically over the past few years. Wind power can now produce electricity at a cheaper price than nuclear power in the UK. Energy from the wind will become cheaper in the future as greater experience is gained in manufacturing and developing this relatively new technology. When the full costs of the environmental damage caused by fossil fuels and nuclear power are taken into account, wind power is economically and environmentally is an attractive option.

It has been estimated that if the cost of environmental damage were included, the price of electricity from coal would be three times higher than electricity generated from the wind. The full costs of nuclear power, which include dealing with highly radioactive waste and decommissioning of old plants, are not included in the calculated electricity price from this source.

A Government report on energy policy (the PIU report (Performance and Innovation Unit)) predicted that by 2020, the cost of generating electricity from nuclear power would be 3-4p per kWh, whereas the cost of production from offshore wind costs would be 2-3p per kWh. Onshore wind is set to be the cheapest form of electricity generation of all by 2020, and is already competitive with fossil fuels at an average price of 2.88p/kWh

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24. Why are all turbines not located out to sea?

Turbines can be sited offshore, where the wind blows harder and the available resource is enormous. The UK's first two offshore wind turbines have been installed off Blyth in Northumberland. The UK's first large scale offshore wind farm - North Hoyle - commenced construction off the North Wales coast in April 2003, and will consist of 30 turbines able to meet the electricity needs of around 50,000 homes, it is now (Autumn 2004) nearing completion. Another will be constructed in 2004 off the East Anglian coast at Scroby Sands, near Great Yarmouth. Similar sized offshore wind farms are currently being developed in 16 other locations around the British coast.
The urgent need to respond to climate change means that there is a need to use as many renewable resources as quickly as possible, utilising both onshore and offshore wind. At present onshore wind is one of the most economically competitive of the renewable technologies. Due to the technical hurdles of offshore construction and connection to the National Grid, the cost of delivered energy from initial offshore wind farms is estimated to be at least 30 per cent higher than that from equivalent land-based turbines. There are also a number of other constraints on the development of offshore wind resources including a limited number of suitable locations, new consents procedures and objections from the Ministry of Defence, which are likely to slow progress of some of these sites.

The offshore wind resource is huge, the DTI estimates it could supply current electricity demand 10 times over and there is little doubt that offshore wind will become an increasingly important element in the overall supply of electricity. However onshore wind is also essential if the UK renewable energy market is to be successful, and if the Government's target of 10 per cent of electricity generation from renewable sources by 2010 is to be met.

25. How far out to sea will offshore sites be located and how deep?

Most offshore wind farm proposals for the UK are at least 5km from the shore. In the near future offshore wind turbines will generally be built in water less than 30m deep. This will determining factor with regard to how far off the coast they are likely to be sited.

There is much shallower seabed further out into the North Sea off Norfolk and around The Wash than around the South West Coast of England and off South Wales. The latter have more precipitous seabeds that mean any developments would be closer to shore.
Another consideration is the cost of delivering the electricity to shore and the practicality and cost of building and maintaining turbines further out to sea. The further offshore the wind farm, the longer and more expensive the cables needed to plug the electricity into the national grid onshore become.

There are, nevertheless advantages further offshore. Wind speeds tend to be higher and the wind is steadier. Turbines built further offshore should capture more wind energy.

26. Will they interfere with fishing or shipping?

Wind turbines at sea will be spaced between about 500-1000m apart so the physical barriers for all but the largest vessels will be minimal. Nonetheless, at certain sites developers may want to restrict navigation within the site for safety reasons.

This would be done in accordance with domestic and international laws and local sailing organizations (RYA, MCA and others) would be contacted as part of the consultation process. Developers expend significant effort and financial resource on ship surveys to ensure that wind farms are sited where they will have minimum impact on recognised shipping lanes and pleasure boats.

In respect of the impact on fishing there is no evidence to suggest that total fish catch will decline as a result of wind farm developments. Many environmental groups believe that wind farms will provide welcome sanctuary for fish spawning as well as refuge from intensive fisheries activity.

The wind industry is working actively with the fishing industry to ensure, as the oil and gas industry has done before them, that the fishing industry is not disadvantaged by the growth of offshore wind farms.

27. Will they disturb the seabed and cause coastal erosion?

Any proposed scheme will fully investigate the wave and coastal processes prior to construction and include the results of this research in the Environmental Impact Assessment. In addition, some offshore projects have been given consent to go ahead on the condition that they also monitor the effects on coastal processes during and after construction.

The turbine structures and distance offshore are such that it is very unlikely they would significantly affect the seabed or wave patterns. There is no evidence from the Danish experience of offshore wind farms of any detrimental effects on coastal processes.

The coastal erosion effects of higher sea levels and more extreme weather patterns due to global warming are already scientifically recognised, and these far outweigh the potential effects of offshore wind farms.

28. What about other forms of renewable energy?

Wind power is the most mature renewable technology, and can deliver large amounts of electricity at a relatively low cost.
Other renewable sources of energy are also important. The UK has one of the best wind resources in Europe, but it also has a fantastic wave resource (particularly off Scotland). Even solar power has the potential to meet around two third of our electricity needs. Wave and solar, along with tidal power and biomass, will form important parts of the balanced renewable energy mix that the UK urgently needs to replace nuclear and fossil fuels.

29. Isnt energy efficiency just as important?

Energy efficiency is essential. It is the other half of the solution to the UK's energy needs. Decreasing electricity demand can deliver immediate benefits both in terms of carbon reductions and energy security. It is also one of the cheapest short term solutions.

Energy efficiency enhances the benefits of renewables, by reducing the demand on them and making their positive impact on carbon emissions greater and quicker.

However much the use energy is improved there will always be a need to generate electricity. It is vital that better use is made of energy sources that are safe, clean, secure and renewable. Both energy efficiency and wind power have important roles to play in a sustainable energy policy for the future and have massive potential to help solve serious local, national and international environmental problems

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