Energy of the wind
The kinetic energy of wind can be converted into other forms of energy – mechanical or electrical energy.
For example, when a sailboat develops sails, it uses wind energy to navigate the sea. This way of using wind energy has been used for years. The wind also helped discover America – and Columbus’ ships were sailing ships. Wind energy is also used in windmills. In the Netherlands, windmills have been used for centuries to run water pumps in lowland areas.
The wind also drives mills for grinding flour or corn, in a similar way that in mills the mills are driven by the potential energy of water. Today, we also know how to use wind to produce electricity in wind farms. A device for producing electricity from the kinetic energy of wind is not called a windmill but a wind turbine. So, windmills drive flour or corn mills, or water pumps, and wind turbines serve us in wind farms to produce electricity.
How do wind farms work?
The wind rotates the wind turbine blades attached to the shaft connected to the gearbox. In the gearbox, the gear rotation speed is increased by means of a gear mechanism. The gearbox is connected to the turbine shaft on one side and to the high speed shaft on the other. This shaft rotates the generator rotor and thus produces electricity. Not every wind can be used in this way to produce electricity. Sometimes the wind speed is too high – so the turbine has a brake. The brake does not allow the turbine to rotate with too many revolutions, it easily seems like a lot, in order to produce as much electricity as possible in one place, wind turbines are built in large groups. Such groups are called wind farms. Wind farms are, of course, built in areas where winds blow most often and where the blowing speed is suitable.
There are many windy areas in Croatia. The big problem with them is that the wind doesn’t blow constantly. In addition, too weak and too strong wind cannot be used in a wind farm, and the winds that blow in Croatia are often just like that. The bora in Senj and Karlobag is an example of such a wind – very irregular and often too strong. Since 2004, the first wind farm in Croatia has been put into operation on the island of Pag. It consists of 10 wind turbines. For a wind turbine to work successfully, the wind speed must be higher than twenty kilometers per hour. Only a wind of this speed can move the turbine blades fast enough to produce electricity.
The conversion of the kinetic energy of the wind into the kinetic energy of the shaft rotation takes place by means of the blades of the rotor of a wind turbine or wind turbine. In this case, the rotor and the electric generator are located on a common shaft (more precisely, there is a corresponding gear between them).
In the generator, the kinetic energy of the shaft rotation is converted into final, electrical energy, so the whole plant is often called a wind generator.