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Are wind turbines noisy?

Wind turbines are mechanical and do generate low levels of noise when operational, although the evolution of wind farm technology over the past decade has reduced this noise considerably. There are strict guidelines that govern wind turbines and noise emissions to ensure the protection of residential amenity. It is possible to stand underneath a turbine and hold a conversation without having to raise your voice. As wind speed rises, the noise of the wind masks the noise made by wind turbines.

We carry out noise monitoring in the local area surrounding a proposed wind farm to ensure that we can design the wind farm to protect the amenity of local residents and comply with the guidelines.

Do wind turbines produce low frequency noise?

There is always low frequency noise present in any ambient quiet background and it can be produced by a variety of man-made sources, including machinery and transport, as well as natural sources such as the sea, wind and thunder. Measurements of wind turbine noise undertaken in the UK, Denmark, Germany and the USA over the past decade have shown that the levels of low frequency noise and vibration radiated from modern, upwind configuration wind turbines are at a very low level.

Noise monitoring is a key component of the Environmental Impact Assessment we carry out for a proposed wind farm and the findings from our investigations must be submitted with our Planning Application.

Why don't they make turbines that look like old fashioned windmills?

A modern wind turbine is in effect an improved windmill. Every aspect of their design has been optimised for efficiency in generating electricity. While some people view windmills with nostalgia and prefer the look of them to their modern counterparts that doesn’t hold true for everyone. To make modern turbines look more old-fashioned would result in more expensive electricity and reduced output.

Why don't we put all the wind turbines out to sea?

The reality is we will need a mix of both onshore and offshore wind energy to meet the UK's challenging targets on climate change. It wouldn’t be possible to meet our renewable energy obligations with only offshore development.

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.

We currently have one offshore wind farm in operation at Redcar, Teesside.

Do wind turbines frighten livestock?

Wind farming is popular with farmers because their land can continue to be used for growing crops or grazing livestock. Sheep, cows and horses are not disturbed by wind turbines.

We already operate wind farms on land where livestock are kept at our sites at High Hedley Hope and Kirkheaton and the animals can be seen grazing right next to and under the turbines.

How long does it take for a turbine to 'pay back' the energy 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, which is the time needed to generate the equivalent amount of energy used in constructing the wind turbine or power station.

The average wind farm in the UK will pay back the energy used in its construction within three to five months, this compares favourably with coal or nuclear power stations, which take about six months.

How safe is wind energy?

Wind energy is one of the safest energy technologies. It is a matter of record that no member of the public has ever been injured during the normal operation of a wind turbine, with over 25 years operating experience and with more than 70,000 machines installed around the world.

Does wind farming affect tourism?

There is no evidence to suggest that wind farming affects tourism. 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.

What are wind turbines made of?

The towers are mostly tubular and made of steel, generally painted light grey. The blades are made of glass-fibre reinforced polyester or wood-epoxy. They are light grey as this colour is least conspicuous under most lighting conditions. The finish is matt, to reduce reflected light.

The visual impact of a wind farm is another key consideration in our early investigations and our aim is to develop wind farms that are have least impact on the landscape.

How big are wind turbines?

Large modern wind turbines have rotor diameters ranging up to 65 meter while smaller machines (around 30 meter) are typical in developing countries. Towers range from 25 to 100 meter in height.

How strong does the wind have to be for the wind turbines to work?

Wind turbines start operating at wind speeds of four to five metres per second (around 10 miles per hour) and reach maximum power output at around 15 meters per second (around 33 miles per hour). At very high wind speeds (gale force winds - 25 metres per second, or over 50 miles per hour) wind turbines shut down.

We carry out detailed investigations in relation to the likely wind speeds on a proposed site to determine whether it is feasible to develop a wind farm.

How fast do the blades turn?

The blades rotate at anything between 50-100 revolutions per minute at constant speed. However, an increasing number of machines operate at variable speed.

How long do wind turbines last?

A wind turbine typically lasts around 20-25 years. During this time some parts may need replacing.

The very first of the mass-produced turbines, the Vestas 30kW machine, has been in operation since 1980 and has operated steadily throughout its lifetime, without the need for any major components to be replaced.

What happens when a wind farm is taken down/decommissioned?

The requirements for decommissioning a wind farm are stipulated by the relevant local authority in its planning permission. In essence these clauses typically require that all visible traces of the wind farm be removed. With regards to service tracks, each case is different, depending upon the size and geography of the development. Similarly, concrete bases may be left in place and covered with peat, stone or other indigenous material, and the site returned as closely as practicable to its original state. As well as ground restoration, other remedial measures may also be undertaken.

Wind energy technology is essential reversible, and compared to the problems associated with decommissioning a nuclear power station, or a coal or gas fired plant, decommissioning a wind farm is straightforward and simple.

How efficient are wind turbines?

As the fuel source (that is, the wind) for generating electricity from turbines is free, the primary concern is not efficiency for its own sake, but to improve productivity in order to bring the price of wind energy down. The theoretical maximum energy that a wind turbine can extract from the wind blowing across it is just under 60%. Different models of turbine are suited to different wind conditions and we work closely with Energies Nouvelles to establish the type of turbine that is best suited to a particular location to maximise productivity and generate electricity at the lowest price possible.

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

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 is 3-4 pence per unit.

How much of the time do wind turbines produce electricity?

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%.

How much electricity does one wind turbine produce?

One 1.8MW wind turbine at a reasonable site would produce over 4.7 million units of electricity each year, enough to meet the annual needs of over 900 households.

Source BWEA

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