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Questions about Wind Energy
Frequently asked questions
- How many wind farms are there in the UK?
- Where are they?
- How big are they?
- How much electricity do they produce?
- How efficient are they?
- Can wind farms produce significant amounts of electricity?
- How strong does the wind have to be for the turbines to work?
- What happens when the wind stops blowing?
- Are wind turbines noisy?
- How much land do wind farms take up?
- Do wind turbines frighten livestock?
- Do wind farms affect tourism?
- Aren’t wind farms unpopular?
- Isn’t it cheaper just to save electricity?
- Do wind farms interfere with TV reception?
- Can I ask my electricity company to provide me with green electricity?
How many wind farms are there in the UK?
As of January 2007, there were 1,902 wind turbines at 156 sites in the UK. Of these, 6 of the sites are offshore (source: British Wind Energy Association). Further information is available on the British Wind Energy Association's website.
Where are they?
Most wind farms are in Cornwall, Cumbria and the North West, Wales, Yorkshire, Northern Ireland and Scotland. Details of existing wind farms can be found on the British Wind Energy Association's website.
How big are they?
Large, modern wind turbines have rotors up to 65 metres in diameter. The towers themselves are between 25 to 80 metres high. This means that the largest turbines can be over 100 metres high from ground to rotor blade tip.
How much electricity do they produce?
The following calculation can be used to estimate the annual electricity production (in kilowatt hours per year) from a wind turbine of a given power rating (in megawatts):
Rating of turbine (e.g. 2 megawatts) x 24 (hours in the day) x 365 (days in year) x 0.30 (the capacity factor*) x 1,000 (to convert the answer into kilowatt hours, rather than megawatt hours). This gives the kilowatt hours produced per year per turbine. To work out how many households each turbine can provide electricity for, divide this total by 4,400 (the average kilowatt hours used per household per year).
* 0.30 (or 30 per cent) is the average capacity of the turbine, as it does not produce power at 100 per cent all the time, due to factors such as changes in wind conditions, downtime for maintenance. The average value for an onshore turbine in the UK is very roughly 0.3 but this varies from place to place. Offshore turbines tend to operate at a higher capacity of 0.35+ because of stronger and more consistent winds offshore.
How efficient are they?
A wind turbine can extract 60 per cent of the wind’s energy at most.
It is easy to confuse intermittency with efficiency. Wind farms are highly efficient at turning a free fuel source into electricity. However, the wind does not blow all the time, which is why the average capacity is around 30–40 per cent.
Can wind farms produce significant amounts of electricity?
Collectively wind farms can make a huge difference. BERR calculates that onshore wind could supply up to 100 per cent of our current electricity demand, and that offshore wind could generate ten times this amount. Once other factors such as land availability are taken into account, a more realistic potential is around 40 per cent of current electricity generation, using both onshore and offshore wind turbines.
How strong does the wind have to be for the turbines to work?
Wind turbines start operating at wind speeds of four to five metres a second (around 10 miles an hour). They reach maximum power output at around 15 metres a second (around 33 miles an hour). At very high speeds, i.e. gale force winds (25 metres a second or 50+ miles an hour), the wind turbine control system will often shut down the turbine to help prevent damage to the turbine. Some wind turbines, particularly those used in buildings and urban environments, are designed to start producing energy at lower wind speeds.
What happens when the wind stops blowing?
When there’s no wind, no electricity is generated. So there are technical challenges to including this intermittent form of generation into the electricity network. On a small scale this is less of an issue as storage devices, such as batteries, can be used. However, as there are wind farms all over the UK, the changes in power from individual turbines will be smoothed out, because, if the wind drops in one area, it is still highly likely to be blowing in others.
The electricity grid always needs some form of back-up power (usually coal or gas) in case of sudden power stoppages at any power station. The National Grid has estimated that only a little extra back-up is needed to cope with wind power generating more energy. Intermittent energy sources such as wind energy could meet up to 10 per cent of the country’s needs, without significant changes to the system’s operation.
Are wind turbines noisy?
People visiting wind farms are often surprised at how quiet they actually are. The Scottish Executive’s public opinion survey is one of many showing that concerns about noise are often unfounded. A survey conducted before Scottish wind farms were built found that 12 per cent of people living near the potential sites thought that the turbines would be noisy. However, once they had experience of the wind farm operating, only 1 per cent felt this was true.
The main sound that can be heard if you are close to the turbines is the swishing of the blades through the air. As a comparison, a wind farm 350 metres away produces 35–45 decibels. A car travelling 100 metres away at 40mph generates 55 decibels. Background noise in the countryside at night is 20–40 decibels.
How much land do wind farms take up?
A typical farm of 20 turbines covers an area of one to two square kilometers. However, as the turbines take up only 1 or 2 per cent of this land the rest can still be used for agriculture.
Do wind turbines frighten livestock?
Wind farming is popular with farmers, because they can continue to use their land for growing crops or even grazing livestock, as sheep, cows and horses are not disturbed by the turbines.
Do wind farms affect tourism?
There is no evidence to suggest that wind farms deter tourists. In fact, many wind farms are actually tourist attractions.
For example, 350,000 people visited the UK’s first commercial wind farm in Delabole, Cornwall in its first eight years. The Gaia energy centre opened at the site in 2001 and received 50,000 visitors in its first year. In Swaffham, Norfolk, tourists queue to climb the wind turbine tower to get to the viewing platform at the top.
In Scotland, a MORI poll in 2002 found that 80 per cent of tourists said they would be interested in visiting a wind farm in Argyll if it were open to the public and had a visitor centre.
Aren’t wind farms unpopular?
Surveys undertaken by BERR and other organisations show broad support for the expansion of renewable energy.
A BERR-commissioned survey in March 2007 of awareness and attitudes towards renewable energy discovered that public support for renewables remains high. The quantitative research project explored awareness and attitudes to renewable energy amongst the general public in Great Britain. The survey revealed that 83% of the general public supports the use of renewable energy, 82% are in favour of wind power and 59% would be happy to live within 5km (3 miles) of a wind power development.
Another survey for BBC Scotland has suggested that more than half of adults in Scotland favour renewable energy sources like wind power to supply future needs. Of the 1007 people who responded to the survey, 52% saw renewable energy sources like wind, tidal, solar and wave power as the "preferred method of meeting future energy demands in Scotland".
Isn’t it cheaper just to save electricity?
No matter how much we improve how we use energy, we will always have to generate it. It is vital that we make more use of safe, clean, secure and renewable energy sources.
Both energy efficiency and wind power are important to a future sustainable energy policy. They have the potential to help massively in solving serious local, national and international environmental problems.
Do wind farms interfere with TV reception?
Wind farms can occasionally affect TV and radio signals. However, suitable repeater equipment or TV aerial modifications can easily solve any problems found during the planning process.
Can I ask my electricity company to provide me with green electricity?
Since 1998 – when the energy market was opened up to competition – you can switch to a ‘green’ supplier. There are generally two main types of ‘green’ electricity tariffs (some schemes provide a combination of both):
- energy schemes that promise to buy renewable energy to match some of your electricity usage – some of these schemes ensure that suppliers exceed their legally obliged levels of green supply
- fund schemes that put money aside to fund environmental projects.
From 1 July 2004, new legislation required individual electricity supply companies to disclose how much each energy source contributed to the overall fuel mix of the supplier the previous year.