Did you know?
Why do wind turbines usually have 3 blades?
The wind is slowed by obstacles on the ground (trees, buildings…). Its speed thus increases with height. The wind’s force is stronger at the level of the highest blade versus the lowest blade. This difference leads to a twisting of the rotor’s axis. On one hand, an even number of blades would lead to mechanical constraints and increase the wear and the risk of the system’s incapacity. On the other hand, an odd number of blades (thus a lay-out without vertical opposition) reduces these constraints. Moreover, this diminishes the vibrations and thus the noise released by the wind turbines.
In addition, each blade generates turbulence that bothers the next blade and reduces the overall yield of the machine. Three blade wind turbines are thus more efficient and more silent: they reduce the mechanical constraints and offer a better yield.
Do wind turbines make a lot of noise?
A wind turbine is a source of noise. The manufacturers, cognizant of this problem, have significantly reduced the level of noise generated by turbines and continued technical progress results in a constant reduction of the level of noise generated thanks to:
- The optimization of blade design and their material
- The use of silent gearing systems
- The use of transmission shafts on shock absorbers
- The noise insulation of the nacelle
It is important to note that the noise generated by wind turbines is somewhat covered by the level of noises that increases with the wind speed. From 7 to 8 m/s (25 à 29 km/hr), the wind related noises block out a great deal of the noise of the wind turbines.
The generation of noise also depends on the environment, the site’s topography, vegetation and urbanization. A good understanding of the local environment during the site selection can significantly reduce noise problems. For each wind farm, an impact study including an acoustic study is carried out by an independent firm and guarantees the respect of the acoustic regulations. FUTUREN’s goal is to reduce as much as possible the difference between the surrounding noise and the noise made by the wind turbines.
What about the impact on the landscape?
The perception of the landscape and its modification remain subjective and varies a great deal from one person to another. Visual pollution for some, beautiful object for others, opinions vary a lot. What is certain is that wind turbines do not destroy the landscape more than thermal or nuclear power plants and the stretches of high tension power lines they generate.
For a wind farm, the landscape integration is carefully studied and represents a fundamental point during the development. The installation site under review must protect natural reserves, landscapes or endangered architectural structures, be designed in harmony with its surroundings and to limit possible co-visibilities. Tools such as photo montages enable simulations before any landscape changes related to the installation of wind turbines so as to inform the public. To visualize the future wind turbines in the location allows for an ownership of the project, and thanks to a dialogue, to arrive at an optimal installation of the machines.
Do the lands upon which the wind turbines are installed continue to be used?
When it concerns natural or man-made fields, animals can continue to graze without restrictions or risks from the proximity of the turbines. For farmland, the constraints are the same as those for telephone poles. In addition, the landowners are compensated for the rental of the installation sites.
Do wind turbines present a danger to birds and bats?
Accumulated experience enables us today to better understand and manage the risk that wind turbines present to birds and bats. First of all, the usual impact study, carried out by independent organizations involving at least one full year of observation, identifies endangered or typical nesting species as well as the presence of any migration routes.
The risks of collision in nesting zones and behavior are evaluated and these data are taken into account for the design of the wind farm. The installation of wind turbines is typically located outside any major migration paths. Spaces of several kilometers between wind turbines can also be planned to allow birds to pass.
In general, modern turbines turn very slowly which allows birds and bats to avoid the blades. Studies also illustrate that most migrating species change their behavior as they near wind turbines. In order to further our knowledge of avifauna and bats, observation sessions are often carried out during the operation of the wind farms.
Do wind turbines make animals flee?
During the construction of a wind farm, large animals may be disturbed. For the most sensitive sites, it is important to organize most of the work outside the mating season of most animals.
During a wind farm’s operation, animals easily become accustomed to the presence of wind turbines. Studies have been carried out near operating wind farms; the results illustrate that the behavior and dispersion of animals are nearly identical to that with or without wind turbines.
Does the presence of wind turbines disturb television reception?
The electric and electronic equipment of wind turbines meet the current standards of electromagnetic emissions and are in no way a source of parasites. In addition, during the development of the project, the selection of the location of the wind turbines takes into consideration potential risks of disturbing Hertzian signals and their operators or relays are consulted.
If despite these precautions, disturbances are noted, the head contractor carries out, at his expense, an installation of a receiver to insure satisfactory reception conditions for the area near the construction.
Are wind turbines responsible for the increase in electricity prices in France?
The repeated increase in the price of electricity in France is often explained by the necessity to compensate for the cost of buying electricity produced from green energies. That’s false!
In France there is a public service electricity tax. It is paid by each electricity end according to his/her consumption. This tax covers:
- the obligatory purchase of electricity produced from renewable energies,
- but also the obligation to purchase electricity produced by cogeneration gas,
- the financing of the egalitarian tariff (the fact that consumers in the French overseas territories pay the same rate as French domestic consumers despite a higher cost of electricity production).
Historically, it is indeed the egalitarian tariff and the cogeneration gas that compose most of that increasing tax. Within renewable energies, one should not forget the significant part dedicated to financing the development of photovoltaic solar. As well, keep in mind that in France, the electricity price is around 30% less than the average rates applied in Europe.