Wind comes about from the varied temperatures created by solar radiation on the surface of the earth. These different temperatures cause humidity and pressure levels to vary as well, and the difference in the pressure levels causes the air to move. Approximately 2% of the solar energy which reaches the earth is converted into wind energy.
In meteorological terms, wind can develop in the following locations:
- Locations where changes in pressure are high;
- High, even hills and valleys;
- Regions which are under the impact of strong geostrophic winds;
- Coastal areas;
- Mountain ranges, valleys and hills where canal effects are present.
The characteristics of the wind differs (in respect of time and region), based on local geographic differences and the non-homogenous temperatures of the surface of the earth. Wind is stated as two separate parameters – speed and direction. The speed of the wind rises with height, and its theoretical strength changes proportionately to its cubic speed. The initial investment costs of wind energy applications are high, and their capacity factors are low. Together with this, they have the disadvantage of inconsistent energy production. Their advantages, on the other hand, can be listed as follows:
- In plentiful and free supply within the atmosphere;
- It is a renewable and clean source of energy, and is environmentally friendly;
- Its source is reliable, and there are no risks of running out or prices increasing over time;
- Its cost has reached the level where it is able to compete with the power plants of today;
- Maintenance and repair costs are low;
- It creates employment;
- Its raw materials are completely domestic, and it does not create a dependence on imports;
- The installation and operation of its technology is relatively simple;
- It can be taken into operation within a short time.
The classification of the electricity energy generated from wind, as a function of the average wind speed at the hub height, is given below. Accordingly, the average wind speed at the relevant location is:
6.5 m/s medium level in terms of wind speed energy,
7.5 m/s good,
8.5 m/s and above speeds are evaluated as being very good.
Wind energy has been used from the first ages, by taking advantage of the shaft power of the turbine, for pumping water, cutting various products, shearing, grinding, pressing, obtaining oil, and other similar activities where mechanic energy is needed. The most effective manners of use of wind energy can be summarised as below:
- Mechanical applications (water pumping system);
- Electrical applications (systems with network connections, and stand-alone systems without network connections);
- Thermal energy applications.
Wind turbines are the principal structural elements of wind energy plants, and are machines which convert the kinetic energy of the moving air, first of all to mechanic energy, and then to electricity energy.
Wind turbines can be manufactured either with a horizontal or a vertical axis, based on the direction of their rotational axis. Wind turbines with a horizontal axis are more widely used. These types of wind turbines can be built with one, two, three or multiple propellers. Wind turbines with a horizontal axis are also known either as up-wind or down-wind turbines.
The axes of wind turbines with a vertical axis are straight and vertical towards the direction of the wind, and their propellers are also vertical. Modern wind turbines, which are used for generating electricity, and are connected to the network, mostly have 3 propellers, horizontal axes, and are wind turbines of the up-wind type.
In parallel with the technological developments of our day, wind turbines with horizontal axes with a power of 1,0-7,5 MW are used in the large, powerful wind energy plants. The propeller dimensions of wind turbines with three propellers has reached 100 m, and, indeed, more. The hubs of modern wind turbines are 60-120 m above ground level, on a tower. The amounts of energy which can be obtained from one wind turbine is dependent, in the first degree, on the wind speed at the turbine hub height. Raising the hub higher will ensure maximum benefit from the existing wind power.
Wind turbines are only able to start generating electricity energy at a specific wind speed. A wind turbine will generate energy in between the cut-in and cut-out speeds. The cut-in speeds of modern wind turbines are between 2-4 m/s, their nominal speeds are between 10-15 m/s, and their cut out speeds are between 25-35 m/s. Each wind turbine reaches the maximum power value which can be obtained from the system at a specific wind speed. This maximum power is known as nominal power and the wind speed at this level is known as the nominal speed. Wind turbines automatically stop after a certain wind speed has been exceeded, in order to ensure that the system is not damaged. This maximum speed is known as the system cut-out speed.
The body possesses sound insulation in order to prevent noise pollution. The towers are built in the form of cages or pipes. As the towers can be very high, the constructions outside the cage towers can consist of two or three parts.
It has been accepted that wind plants with a capacity of 5 MW can be established in Turkey at heights of 50 meters above ground level, and in areas with a wind speed exceeding 7.5 m/s. In the light of this acceptance, a Potential Wind Energy Map (PWEM) has been prepared, where the source wind details obtained using a mid-scale weather forecast model and micro-scale wind flow model are given. The wind energy potential of Turkey has been estimated as 48.000 MW. The total area which is equivalent to this potential is just 1.30% of the total surface area of Turkey.
As the end of 2016, the installed capacity of the wind energy plants in operation is 5.751,3 MW.
The details presented here have been prepared with the aim of informing the users of the website of our Ministry, and do not possess the characteristics of official binding documents.