The evolution of electricity in the XX century has determined the appearance of the first modern wind turbines. It has been studied the profile of the blades, and the engineers are inspired by the profile of the plane’s wings. Today, the wind turbines are, almost all of them with horizontal ax, without the models with vertical ax like the ones with rotor for example Savonius and Darrieus, which are still used, but they are a less than the others. The last innovations allow the functioning of wind turbines with variable speed, and also the calibration of wind turbine’s speed depending on the wind’s speed.
The wind power is one of the regenerating energies. Aero-Generator uses the kinetic energy of the wind to drive its primary shaft: this energy is transformed into mechanical energy, which is also transformed in electrical energy by the generator which is mechanical connected to the wind turbine. There are lots of possibilities to use the electrical energy produced: either is stocked in the storage battery, or is distributed through the electric main, or they are powered by the isolated charges.
A wind turbine occupies a small surface of the ground. This is a big advantage, because it disturbs a little the location where is installed, allowing to maintain the industrial or agricultural activities from nearby area. We can find individual wind turbines, installed in isolated areas. The wind turbine is not connected to the network and with other wind turbines. On the contrary, the wind turbines are arranged together like wind farms. The installations can be made on the earth, or, many of them are made in the open seas, which are looking like offshore wind farms, in their case the presence of the wind is steadily. This type of installation reduces the sound disadvantage and improves the aesthetics.
The new demands in the area of the lasting development have determined the world to be aware of the producing methods of energy and to raise the share of energy produced by the regenerating energies. The Protocol from Kyoto engages the signatory countries to reduce the gas emissions which produce greenhouse effects. This agreement has determined the endorsement of a national politics of wind turbines’ development and other sources that doesn’t emi CO2.
Today, on the world plane, the weight of regenerative energies in producing the electric energy is low. It can be said that the potential of different types of regenerative energies, is under-exploited. Although, the technological improvements had encouraged the installation of wind generators, in a permanent ascending rhythm in the past few years, with an exponentially evolution, having in 2003, a growing rate of 25%.
The costs and efficiency of a wind turbine project should take into account both the price of the wind turbine and of its installation and maintenance, as well as the price of selling the energy. Even if the wind turbines of first generation were sound disturbing, it looks like in the present, the technological evolutions have allowed to considerably reduce the noise produced by this kind of instalations. Thus, on the sound scale, the wind turbines are situated somewhere between the noise produced by the wind and the one produced inside of a house, at aproximately 45 dB.
The wind turbine is considered to be one of the most lasting options from future alternatives, the wind resources are huge. It is estimating that the recoverable wind turbine on the world plane is situated at approximately 53 000 TWh (TerraWattora), which represents 4 times bigger than the current global consumption of electricity. In Europe, the potential is enough to assure at least 20% from the electrical energy needed until 2020, especially if we take in consideration the new offshore potential. Savonius wind turbines are a type of vertical-axis wind turbine (VAWT), used for converting the power of the wind into torque on a rotating shaft. They were invented by the Finnish engineer Sigurd J. Savonius in 1922. Johann Ernst Elias Bessler (born 1680) was the first to attempt to build a horizontal windmill of the Savonius type in the town of Furstenburg in Germany in 1745. He fell to his death whilst construction was under way. It was never completed but the building still exists.