WIND POWER - FAQ

What power does a wind turbine generate and how big are they?

Turbines installed today usually generate between 1 and 3 megawatts. The size of a wind turbine, and in particular the diameter of the rotor, is directly related to the amount of power it generates. The amount of energy recuperated when the wind crosses the rotor is proportional to its surface. Therefore, a 1 megawatt turbine will have a rotor diameter of approximately 55m and a 2 megawatt turbine will have a rotor diameter of approximately 80m.

So that the turbine's rotor can capture the most wind possible under the best conditions, it must be placed high up using a mast. The size of the mast which the rotor is fixed to (with a nacelle) has nothing to do with the power of the wind turbine. It is adapted to the conditions of the site: topography, force and quality of the wind, presence of trees, access conditions to the site, easement constraints. Generally, a 2 megawatt turbine is approximately 120m high at the blade tip.

What quantity of electricity does a wind turbine produce?

The quantity of electricity produced by a wind turbine is expressed in kilowatt-hours and depends on the type of wind to which it is subjected. Thus, two wind turbines of identical power, installed on sites with different wind flows will not produce the same amount of electricity.

Example: A 2 MW wind turbine produces 2000 kw per hour at full power

What is the lifespan of a wind turbine?

As for any type of mechanical equipment (car, machine, tool), the lifespan of a wind turbine depends on the maintenance it receives during its operation. Under normal operating and maintenance conditions, a wind turbine is destined to last 20 to 30 years.

When a turbine finally stops operating, French law has made dismantling compulsory and the operator has to allocate a budget right from the start of construction of the project.

Are wind turbines noisy?

When it functions, a wind turbine is a source of noise. The noise produced is relatively low, as at the foot of the turbine the noise level is 55 decibels (dB).



This noise level must be appreciated in the environment where the wind turbine is installed. This is known as "environmental noise". The environmental noise is always different depending on whether it is night or day, and it increases according to the wind. During the day, environmental noise can vary from 35 to 55 decibels and at night the background noise generally varies from 30 to 40 decibels according to the sites.

In France, wind farms are subject to the regulation on noise and neighbourhood (circular dated February 27th 1996, implemented pursuant to the Noise Law dated December 31st 1992). It is the concept of noise emergence produced by the wind turbine in comparison to the environmental noise (noise above and beyond the turbine noise) which applies. This emergence is regulated and must be lower than 5 dB during the day and 3 dB at night.


What effect does a wind turbine have on its environment?

Most of the world's energy (more than 80%) comes from fossil fuels (coal, oil, gas) or uranium. These stocks, constituted over the ages and through geological evolution, are limited. Their combustion, in various forms, lets off important quantities of gases (mainly nitrogen oxide and CO2) into the atmosphere which contribute to increasing the greenhouse effect and thus global warming.

By opposition, wind power is renewable, unlimited and clean and therefore helps limit CO2 emissions into the atmosphere. For example, a 2 megawatt wind turbine installed on a fairly windy site (2 000 hours of full power production) produces 4 million kWh per annum and represents a saving in CO2 emissions of approximately 1 100 tonnes per annum.

Wind power has many other advantages:

• It is an energy source with low ecological impact : When turbines are erected outside ecologically sensitive zones they have very little impact on the local environme
• It is an energy source with a low energy content : A modern wind turbine rapidly produces all the energy necessary to manufacture, install, maintain and dismantle it. Under normal climatic conditions, a modern turbine produces, in only two to three months, all the energy needed for these purposes.
• It is a decentralized energy source which contributes to local economic development (civil and electrical engineering infrastructures, income from land occupation, tax revenues for the local communities…).
• It is one of the means of producing electricity that generates the most employment : The French Renewable Energy Syndicate estimates that 60.000 jobs will be created in France in the wind power sector by 2020.
• It is totally reversible : French law has made dismantling wind turbines compulsory at the end of exploitation. Technically, the dismantling of a wind turbine is just as simple as its erection.

Is it necessary to compensate, by other means of electricity production, the periods when a wind turbine does not produce energy due to the absence of wind?

Nuclear power plants make up 80% of the electricity production in France and are therefore considered as the "Base" production. Electricity consumption fluctuates during the day and also depending on the time of year and therefore periods of peak demand are covered by hydro, thermal and wind.

In its "Estimate of the supply-demand balance of electricity in France" the RTE (Réseau de Transport d'Electricité) analyses the contribution of wind power to periods of peak demand:

« […] despite the intermittency of wind, the existence of wind farms reduces the need to use thermal powered installations to ensure a secure level of required supply. In this sense, we can say that reply to demand is substituted by wind farms.

The level of substituted power (ratio of the thermal power substituted to the installed wind power) is close to the average load factor of wind turbines in winter (approximately 30%) for a low power wind farm (a few GW - nb: this being the current situation).

[…]the de-correlation of wind speeds is quasi-total between the Mediterranean zone and the Channel zone; moreover, in the Channel area, the correlation between Nord-Picardie on one side and Brittany on the other is low. If the global French wind park were to be developed in a geographically balanced way between these different zones, then regional variations could be compensated, and this would allow a greater regularity of national production. »

For more information : www.rte-france.com/

Do wind turbines affect your health?

Following various scientific studies undertaken by the French Environment & Energy Agency (ADEME) and the Renewable Energies Liaison Committee (CLER), it has been confirmed that wind turbines have no harmful effects on health, either for inhabitants living close by or for the on site workforce, much more exposed.

There are approximately 50.000 wind turbines erected in the world, of which some have been functioning for more than 20 years. No problem of public health has ever been raised. The materials employed to build turbines are completely innocuous. They are non toxic, ordinary materials (steel, glass fibre, copper).

According to the ADEME :

«Wind turbines produce electricity ;

• without harming the quality of the air;
• without polluting the waters;
• without polluting the soil.

In this domain and at a national level, the effect of wind farms on public health is favourable»

Source :
Guide pratique, Les Eoliennes, ADEME

Are wind turbines erected on arable land an obstacle to farm labour?

Wind turbines erected on farm land are in no way an obstacle to agriculture. The plot used for the erection and operation of a wind turbine corresponds to the area covered by its foundation and the necessary area for lifting all of its components (mast, nacelle, rotor), known as the crane pad.

In grazing areas, where the plots of land are sometimes very large, the land surface taken up by wind turbine is often lower than 1% of the total surface. The wind turbine itself is not fenced off. In the majority of the cases, a simple improvement of the existing accesses suffices.

In cultivated areas, an effort is made to erect turbines at the edge of a plot of land in order to reduce any disturbance of farm work.

The land owners and farmers perceive a rent or an annual allowance in relation to the size of the plot.

Are offshore wind turbines an obstacle for fishermen?

The erection of offshore wind turbines necessitates specific measures concerning fishing and navigation within their immediate perimeter.

• Angling and yachting: observation of a security perimeter of 50m around the wind turbines for navigation, fishing and mooring off.
• Trolling: observation of a security perimeter of at least 50m around the wind turbines for navigation, mooring off and dredging and of 75m around the cables for mooring off and dredging.

These measures are indicative only and are in no way mandatory. The regulation on this subject should evolve in the years to come with the development of future offshore wind farms.

The foundations of offshore turbines create artificial reefs, which in turn recreate small ecosystems which attract fish. This phenomenon is particularly beneficial to anglers.

The amount of space taken up by an offshore wind turbine is extremely limited in comparison with the immensity of the sea. In addition, within the framework of operating such type of equipment, 50% of the taxes generated are either allocated to the fishing industry or yachting.

What are the economic repercussions linked to building a wind farm?

In 2006, the Mediterranean Environment Agency published a report on the local economy and employment entitled "The Economic and Social Repercussions of Wind Energy in Languedoc-Roussillon - Ten Years of Wind Farms in Languedoc-Roussillon". Source: www.ame-lr.org/publications/energie/retombees_eolien/retombees_eco.pdf). This report underlines the importance of the wind energy industry in the development of the regional economy. The main conclusions are:

- The average cost of installing a wind farm in the region is approximately 1300 €/kW, 19% of which goes to local companies. For the installed working capacity as of Spring 2004, that represented for companies in the Languedoc-Roussillon area nearly 22 Million Euros.

- When taking into consideration all of the activities related to the installation of the wind farms, this represents the creation of 70 direct jobs between 1999 and 2003, and a ratio of 2,9 people / year / MW in indirect employment, that is to say over 11 years, 29 full-time positions.

- To which must be added the jobs created by the operation and maintenance of the existing wind farms, equivalent to 0,38 full-time positions per MW. In 2003, 40 people worked for the maintenance of the wind farms in the region.

- The rent paid for the land on which the wind farms are built is on average about 1500€/MW, which generates a healthy revenue for land owners where wind turbines are put up.