In the world 80% of the energy used is produced by burning fossil fuels, including oil, coal, natural gas.
Plants using fossil fuels generate polluting gases that damage the environment. In recent years to protect the environment and to compensate for the growing demand for energy, the states of the world have pledged to pursue a model of sustainable development, including the exploitation of the kinetic energy produced by the wind.
The need to find alternative sources of energy spread due to the economic crisis of 1973 when the Arab Countries increased oil prices which caused, among other things, the increase in the price of electricity, consequently increased among United exhaustibility awareness of fossil fuels and the need of seeking alternative and renewable resources.
By way of example, a wind power plant consists of onshore wind turbines 30 300 kW each in an area where the wind is blowing at a speed of about 25 km / h can produce 20milioni kWh per year, or the needs of about 7000 families. A central coal to achieve the same result would release the air 22mila tons of carbon dioxide, 125 tons of sulfur dioxide and 43 tons of nitrogen oxide.
ORIGINS OF WIND POWER PLANTS
The first use of wind occurred in prehistory through the use in the sails of the boats and ships of marine propulsion.
The first windmills appeared in Persia and Mesopotamia around the II-III millennium BC, where wind energy was used to transport water or to move millstones and grind grain.
In Holland, wind energy was used to pump water from the polder (parts of land under the sea level). These mills were formed by frames of wood on which the cloth that was fixed in this way formed of the sails driven in rotation by the wind.
Recently, wind energy is exploited by means of impellers to be converted into electrical energy.
CHARACTERISTICS OF WIND POWER PLANTS
There are two types of wind turbines: onshore wind farms that are placed on land and impiantioffshore that are installed plants a few miles from the coast of seas or lakes, for the best use of the strong exposure to the currents of these areas.
There are also off grid wind power plants, wind power plants in other words independent, used in the production of electricity for self-consumption. They are not connected to the national grid, as they are designed to satisfy the needs of individual energy. These systems are ideal especially for those who live in mountain huts or in windy regions. Those who install wind turbines off grid are free from the cost of energy bills.
The distance between wind turbines is calculated to avoid mutual interference, they must be located at least 5 10 or times the diameter of the blades. To determine where to install a wind farm, you need to know:
- The conformation of the ground, which influences the speed of the wind and must belong to a class of low roughness and present a gradient between 6 and 16 degrees;
- The direction and speed of the wind. The direction can be classified according to the geographical origin or the "Rose of the Winds". The force may be indicated or the measure of its speed (knots) or through the scale proposed by Beufort.I modern windmills are called wind turbines. The movement of rotation of the blades of the wind is transmitted to a generator that produces electricity.
Modern windmills are called wind turbines. The movement of rotation of the blades of the wind is transmitted to a generator that produces electricity.
There are several models of wind turbines in shape and size, the most used are of medium size wind turbines: 50 meters in height, with two or three blades of 20 meters, is capable of providing a power of 500 / 600 kW and satisfies the need electricity 500 family around.
The wind turbine is composed of:
- The rotor consists of a hub on which the blades are fixed (often glass fiber) that can rotate at a higher speed than 200 km / h;
- the driving system. The wind turbine is equipped with an aerodynamic braking system which is used comefreno emergency to stop the rotor in case of overspeed of the wind and a mechanical braking system, used to complete the stopping of the rotor and as a parking brake;
- The tower and the foundations. The tower is built of wood reinforced concrete, steel or synthetic fibers in the form of tubes and its job is to support the nacelle and the rotor. The foundation, through which the tower is anchored to the ground, they are usually reinforced concrete;
- The gearbox. Its purpose is to transform the slow rotation of the blades in a faster so that the electricity generator functions;
- The generator. It converts the mechanical energy into electrical energy;
- The control system. It has two functions: to manage the wind turbine in its different work functions and operate the safety device which, in case of malfunction and Overload for an excess of wind speed, stops operation dell'aerogeneratore;
- The spacecraft and the yaw system. The nacelle is a cabin in which are placed all the components dell'aerogeneratore, it is arranged on the top of the tower and is able to turn 180 ° on its own axis. The yaw system is a servo mechanism which ensures a continuous alignment between the rotor axis and the wind direction. In case of deviation of the axis of the wind direction, the vane drives a motor that realigns the spacecraft.
WIND ENERGY IN ITALY AND THE WORLD
At the end of 2011, the generating capacity of the wind turbines worldwide was 237 gigawatts; the overall production potential, evaluated approximately 500 TWh is approximately 3% of the electricity consumed in the world.
The first place in the world for installed capacity of China with 62 gigawatts of installed capacity, followed by the United States of America (47) and Germany (29).
In Italy the first wind machines were installed in 1990, but only from 1996 has had a significant number of plants connected to the electricity distribution network. The contribution of renewable sources in Italy is del7,4%.
The regions most affected are those in the south especially Campania, Puglia, Molise, Sicily and Sardinia.
The advantages of renewable energy, particularly wind power are:
- The use of an energy source, the wind, renewable, sustainable, inexhaustible and environmentally friendly;
- Not the gas is produced earth CO2 , Except in small quantities for the construction of the plant;
- The size of the wind farms are suited to meet the needs of small towns or provinces sparsely populated, since it is easily scalable in power;
- The costs of maintenance and decommissioning are very low since many components are recyclable and reusable.
- There is room for improvement in cost, in the transformation of the current mechanical and electrical current to storage through the use of batteries.
There are some side effects of the plant:
- The occupation of the territory. The wind turbines and works to support occupy only 2-3% of the land needed for the construction of the plant (the remaining part of the territory can be used for agriculture and grazing).
- Visual impact. The wind turbines for their configuration are visible and in some cases disfigure the landscape
- Noise. The noise that emits a wind turbine blade is caused by friction with the air and the multiplier of the turns. The noise from a wind turbine should be less than 45 decibels in the vicinity of housing
- Effects on flora and fauna. The only observed effects relate to the impact of the birds with the rotor of the machines.
- Interference on telecommunications and electromagnetic effects. The activity of the wind turbines can interfere conl'attività radar.
- In conclusion, the advantages of wind farms to protect the environment and the welfare of the individual are qualitatively outweigh the disadvantages, which can be alleviated with small steps, such as the form carefully choose the color and size of the wind turbines because they harmonize with the landscape.