Frequently Asked Questions

Below are some of the most commonly asked questions about Wind Energy.

What is wind power?
Are wind turbines noisy?
Why don’t they make turbines that look like old fashioned windmills?
How much land does a wind turbine take up?
Why don’t we build all the wind turbines out at sea?
Do wind turbines frighten livestock?
Is there an issue with bird mortality?
How long does it take for a turbine to “pay back” the electricity used to manufacture it?
How much does wind power cost?
How much electricity does one turbine produce?
How popular is wind energy?
How safe is wind energy?
Does wind farming affect tourism?
What are wind turbines made of?
How big are they?
How does a wind turbine make electricity?
How strong does the wind have to blow for the wind turbines to work?
How fast do the blades turn?
How much space do wind turbines require?
What happens when the wind stops blowing?
How long do wind turbines last?
What happens when a wind farm is taken down / decommissioned?
How efficient are wind turbines?
Why don’t wind turbines have lots of blades?
Why do some wind turbines have two blades while others have three?

FAQs courtesy of Cielo Wind Power and the British Wind Energy Association

Below is a downloadable FAQ document courtesy of the American Wind Energy Association
Download .pdf document

What is wind power?

Wind power is the result of using the wind to generate electricity. In the past windmills were used to grind grain or pump water. Today, a large wind turbine can power all the electricity needs of about 350 homes. There are many different methods of producing electricity, including burning coal and other fossil fuels. Yet most of these ways hurt the environment by polluting the air and water, and releasing dangerous gases into the Earth's atmosphere. Wind power does not have these effects, which is why we call it a clean, Earth-friendly energy source.

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Wind turbines are not noisy. 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. The noise level is measured in decibels (dB) and for an operating turbine, can range from approx 99dB to 103 dB, where 60dB is the level of Normal Conversation and 100dB is about the volume of a walkman at maximum level.

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The old fashioned windmill is viewed with nostalgia, and some people prefer the look of them to that of their modern counterparts. Just because wind turbines are modern, it doesn't mean they won't look just as good over time.

A modern wind turbine is simply an improved windmill. Every aspect of their design has been optimized, making them far more efficient than old style windmills at generating electricity. To make them look more old-fashioned would just result in more expensive electricity.

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The actual space that a turbine tower occupies is small, usually less than 100 square feet, but some towers require fenced-in enclosures for additional monitoring equipment, transformers, and other equipment.

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It is more expensive to have offshore wind farms, although the price is coming down. However, the stronger and more constant winds generally found at sea means that more electricity can be generated.

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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.

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Migratory bird “flyways” make a minimal impact on bird populations. In fact, overhead high-voltage power lines, and automobiles pose significantly greater threats to birds than do wind turbines. Most wind turbine companies takes many steps to ensure that wind projects have minimal impact to birds, such as: using underground wires and tubular towers to eliminate bird perching, and U.V. reflective paint to make sure that birds see the turbines. As well, as part of the initial site survey, companies conduct avian studies so that turbines are not located in the way of migratory paths.

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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 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 compares favorably with coal or nuclear power stations, which take about six months.

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Electricity generated by wind turbines typically costs around 5 cents per kWh. This is competitive with traditional sources of electrical generation and is the cheapest renewable energy source. Considering factors such as the rising cost of fossil fuels, the cost of pollution including greenhouse gasses, and the cost of site rehabilitation when a power plant closes, the cost of wind power is competitive with, and may actually be less than, fossil fuels. After a wind turbine is purchased and installed, the operating costs are minimal and the fuel is free.

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Simply put, an average one megawatt wind turbine will produce enough energy for the annual needs of 350 average households. The amount of energy produced by a turbine varies depending on several factors, namely the size and reliability of the turbine, and the speed that the wind is blowing.

These factors together produce the turbine’s capacity. Typically modern turbines range in size from 660 kilowatts to 2.4 megawatts of capacity. They are placed in fairly windy locations with minimum wind speeds in the range of six meters per second (around 13 miles per hour). Wind turbines generally run at 30 to 40 percent capacity, so a 1 MW turbine could produce around 3 million KWh of electricity in a year.

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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.

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Wind energy is one of the safest energy technologies. No member of the public has ever been injured by wind energy or wind turbines anywhere in the world, despite the fact that there are now around 35,000 operational wind turbines

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

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The towers are mostly tubular and made of steel, generally painted light grey. Some towers are made of concrete. The blades are made of glass-fibre reinforced polyester or wood-epoxy. They are light grey because this is the colour which is most inconspicuous under most lighting conditions. The finish is matte, to reduce reflected light.

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Modern wind turbines have rotor diameters ranging on average at around 65 meters while smaller machines on average are around 30 metres, larger machines have diameters in and around 114 meters. Towers range on average from 25 to 80 meters in height, although they can reach as high as approx 124 meters.

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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 generator, which is located inside the nacelle. The nacelle is the large part at the top of the tower where all the electrical components are located.

As the blades turn, the drive shaft turns and produces electricity. The electricity flows down the tower and into a transformer located outside the turbine. Inside the transformer, the electricity from the turbine is converted into an electricity that we can use for power. The power flows to the project's substation and then into a large power grid. From here, the wind generated electricity is sent through utility lines to its final destination.

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Wind turbines start operating at wind speeds of 2.5 metres per second (m/s) and reach maximum power output (or cut out wind speed) at around 28-34 m/s. At very high wind speeds, i.e. gale force winds, (25 metres/second, 50+ miles/hour) wind turbines shut down.

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The blades rotate at a variable speed depending on the size of the wind turbine and wind conditions. This can range from 18-46 revolutions per minute (rpm) for smaller machines and 8-13 rpm for larger machines.

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

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When the wind stops blowing, electricity continues to be provided by other forms of generation, such as gas, diesel, hydro etc. depending on the area and local power suppliers.

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A wind turbine typically lasts around 20-25 years.

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The way that a planning authority wishes to have a wind farm decommissioned should be covered by clauses in its planning permission. These clauses typically require all visible traces of the wind farm to be removed. This takes care of the turbines. Service tracks, if there are any, could be removed, although it may be best to leave them. Obviously each case is different, depending upon the size and geography of the development. Developers will then comply with these clauses.

The concrete bases could be removed, but it may be better to leave them under the ground, as this causes less soil disturbance. If so, they would be covered with peat, stone or other indigenous material, and the site returned as closely as practicable to its original state.

Compared to the problems associated with decommissioning a nuclear power station, or a coal or gas fired plant, decommissioning a wind farm is straight forward and easy!

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The theoretical maximum energy which a wind turbine can extract from the wind impinging upon it, is around 60%. However the meaning of efficiency is different with wind energy, where the fuel is free. The primary concern is not the efficiency for its own sake, but to improve productivity in order to bring the price of wind energy down.

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People often wonder why there aren't more blades on wind turbines. The optimum number of blades for a wind turbine depends on the job the turbine has to do. Turbines for generating electricity need to operate at high speeds, but do no need much torque or turning force. These machines generally have three or two blades. On the other hand, wind pumps operate with plenty of torque but not much speed and therefore have many blades.

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The majority of modern wind turbines have three blades. The advantages of three bladed turbines are greater energy output, and greater aesthetic appeal. The disadvantages are that they cost and weigh more and can be more difficult to install.

Two bladed machines are cheaper and lighter. They have higher running speeds, which reduces the cost of the gearbox and they are easier to install. However two bladed machines can be noisier and appear 'jerky' when they turn.

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