The evolution of wind farm technology over the past decade has rendered mechanical noise from turbines almost undetectable with the main sound being the aerodynamic swoosh of the blades passing the tower. There are strict guidelines on wind turbines and noise emissions to ensure the protection of residential amenity. As wind speed rises, the noise of the wind masks the noise made by wind turbines. A report by the Centre of Sustainable Energy (Page 25) highlights the latest evidence regarding noise made by a wind farm, along with the levels of noise that a wind farm must adhere to.
Why not visit a wind farm and experience it for yourself?
We will need a mix of both onshore and offshore wind energy to meet the UK’s challenging targets on climate change. At present, onshore wind is more economical than development offshore. Furthermore, offshore wind farms take longer to develop, as the sea is inherently a more hostile environment. To expect offshore to be the only form of wind generation allowed would therefore be to condemn us to miss our renewable energy targets and commitment to tackle climate change.
Here in the UK, we are lucky enough to have good winds both on and offshore, and the first offshore turbines at Blyth began generating electricity in December 2000. More offshore wind farms are now generating at locations around the coast, and more are under construction or planned.
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 six months (Centre of Sustainable Energy, Page 1), this compares favourably with coal or nuclear power stations, which take about six months.
Wind energy is one of the most popular energy technologies. Opinion surveys (Guardian newspaper) regularly show that more people are in favour of wind energy than not, and a much higher percentage would rather live within 2 miles of a wind farm as opposed to other forms of renewable energy such as nuclear.
There is no evidence to suggest this. The UK’s first commercial wind farm at Delabole received 350,000 visitors in its first ten years of operation. A MORI poll in Scotland showed that 80% of tourists would be interested in visiting a wind farm. Furthermore, wind farm developers are often asked to provide a visitor centre, viewing platforms and rights of way to their sites.
One of the most helpful things you can do is to help win the debate on wind energy. Respond to letters in local and national papers, participate in radio phone-in programmes and wherever else the opportunity arises. Don’t be one of the silent majority.
You can also choose who supplies your electricity and even where that electricity comes from. ‘Green’ electricity generated from renewable resources is available from all electricity suppliers, in line with Government’s Obligation on electricity companies to source 20% of their supply from renewable energy. You can compare and contrast the different green tarrifs available online at uSwitch.com.
Take a look at the latest RenewableUK database where you can find which wind farm is closest to you. You can also find out about projects which are Operational, Under Construction and Consented.
Large modern wind turbines can have rotor diameters ranging up to 136 metres high, while towers can range from 25 to 150 metres in height; however this is rarely seen in the UK.
The simplest way to think about this is to imagine that a wind turbine works in exactly the opposite way to a fan. Instead of using electricity to make wind, like a fan, 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.
When the wind stops blowing, electricity continues to be provided by other forms of generation, such as gas or coal-fired power plants. Our electricity system is mostly made up of large power plants, and the system has to be able to cope if one of these goes out of action. It is possible to have up to 10% of the country’s needs met by intermittent energy sources such as wind energy, without having to make any significant changes to the way the system operates. More can be accommodated, but extra storage capacity or spinning reserve would be necessary, which would have a cost implication.
The theoretical maximum energy which a wind turbine can extract from the wind blowing across it is just under 60%, known as the Betz limit (REUK). A modern wind turbine produces electricity 70-85% of the time, but it generates different outputs dependent on wind speed. Over the course of a year, it will generate about 30% of the theoretical maximum output. This is known as its load factor. The load factor of conventional power stations is on average 50%.
Wind energy is one of the cheapest of the renewable energy technologies. It is competitive with new clean coal fired power stations and cheaper than new nuclear power. The cost of wind energy varies according to many factors. An average for a new onshore wind farm in a good location is 3-4 pence per unit, competitive with new coal (2.5-4.5p) and cheaper than new nuclear (4-7p). Electricity from smaller wind farms can be more expensive.