Wind farms

What is wind energy?

Wind energy is a form of renewable energy that uses the force of the wind to generate electricity. It relies on the conversion of the wind’s kinetic energy into mechanical energy, then into electrical energy using wind turbines. Wind power is an environmentally friendly solution that contributes to reducing greenhouse gas emissions, as it does not generate any direct pollution during electricity production.

How does a wind turbine work?

A wind turbine captures the force of the wind using its blades, which rotate when the wind blows. This movement drives a generator that converts mechanical energy into electricity. Modern wind turbines, often arranged in “wind farms,” can generate electricity on a large scale and power thousands of homes.

Types of wind turbines

There are two main types of wind turbines:

Onshore wind turbines, installed on land, which are the most common type.
Offshore wind turbines, installed at sea, which benefit from more consistent and powerful winds.

A pillar of the energy transition

Wind energy is now one of the main sources of renewable energy worldwide. In Europe, it plays a key role in the transition to cleaner and more sustainable energy production, replacing fossil fuels.

The advantages of wind energy

Renewable: Wind is an inexhaustible resource.
Clean: It does not emit CO2 during production.
Economical: Once installed, a wind turbine has low maintenance and operating costs.

Diagram of a wind turbine

FAQ

Is a wind farm noisy?

Wind power raises the issue of noise pollution. In France, noise emissions from wind turbines are highly regulated and complaints from local residents are rare. The acoustics of wind farm sites are regulated by the ICPE decree of 26 August 2011, which has been applicable to all French wind farms since 1 January 2012.
The regulations set an ambient noise threshold of 35 decibels (dB) in regulated areas, as well as maximum permissible values when this threshold is exceeded. These values are 5 dB during the day and 3 dB at night (from 10 p.m. to 7 a.m.). If a wind turbine has a noise impact greater than the authorised thresholds, the developer can install serrations on the wind turbine blades. This device, inspired by owl feathers, can significantly reduce the noise impact of the wind turbine.

How much concrete is used in the foundations?

The foundations of wind turbines, which ensure the stability of these tall structures, require a significant amount of concrete. On average, a large onshore wind turbine (2 to 3 MW) rests on a circular foundation approximately 15 to 20 metres in diameter and 2 to 3 metres deep. This represents approximately 400 to 800 m³ of concrete, or between 800 and 1,500 tons of concrete per wind turbine, depending on the type of soil and the size of the turbine. The concrete is reinforced with steel to ensure durability and resistance to wind forces.

The amount of concrete used for the foundations of a wind turbine is roughly equivalent to that of four 70 m² houses, or about 34 concrete mixer trucks.

Why are wind turbines sometimes shut down?

Wind turbines are sometimes shut down for several reasons:

when they are undergoing maintenance
when wind speeds exceed 25 m/s
when wind speeds are below 2 m/s
when electricity purchase prices are negative

Do wind turbines require rare metals?

As in many technological fields such as telephony and television manufacturing, energy and communication technologies, etc., rare metals can sometimes be used in certain parts of wind turbines to improve technological efficiency, particularly in permanent magnet generators for offshore wind turbines. These rare metals are mainly used in direct drive turbines, which do not require a gearbox.

It should be noted that only a very small proportion of French onshore wind turbines contain rare metals and that the industry is committed to reducing its consumption of rare metals.

What impact do wind turbines have on farm animals?

A lot of scientific studies have shown that wind turbines have no significant impact on animals. Cows, sheep and horses continue to behave normally in the vicinity of wind farms. The few cases reporting unusual behaviour could not be clearly linked to the wind turbines themselves. In general, the presence of wind turbines does not affect the health, reproduction or milk production of animals. Furthermore, some wind farms coexist with agricultural and pastoral activities without generating conflicts or measurable impacts.

How is the land restored after a wind farm has been in operation?

At the end of a wind farm's lifespan (approximately 20 to 25 years), the wind turbines can be dismantled and the site must be restored. This includes dismantling visible structures such as turbines, masts and transformers. With regard to the foundations, regulations often require the concrete to be removed to a depth of at least 1 metre, allowing the land to be returned to agricultural or natural use. The land is then rehabilitated to restore it to its original condition or to make it suitable for other uses. The cost of dismantling is generally covered by a bank guarantee provided at the start of the project.

Why are there flashing lights on wind turbines at night?

Flashing lights (navigation lights) on wind turbines are required by regulation to ensure aviation safety. These flashing lights are visible from a distance to prevent any risk of collision with aircraft. However, these flashes can disturb local residents at night. InnoVent has developed an innovative aircraft transponder detection system. This system would activate the lights only when an aircraft is detected nearby, significantly reducing light pollution for residents. Although this solution has been successfully tested, it has unfortunately been rejected by the authorities for regulatory reasons.

What are the tax benefits for municipalities where wind turbines are installed?

Wind farms generate several types of tax revenue for local authorities:

IFER (Flat-rate tax on network companies): Each onshore wind turbine with a capacity of more than 2.5 MW generates approximately €7,500 per year.
Property tax: The owners of the land on which the wind turbines are installed pay a property tax that benefits the municipality.
Territorial economic contribution (CET): Companies operating wind farms pay a contribution to local authorities.

Overall, for a municipality that hosts a wind farm with 10 wind turbines, the tax revenue can reach between €50,000 and €100,000 per year, depending on the size of the wind farm and local tax regulations. This money can be reinvested in local projects such as infrastructure, schools or public services.