Wind turbines are used to produce renewable and green energy. They do this by converting the kinetic energy from the wind into mechanical energy, and then into electricity. Basically, it is the opposite of a fan. A wind turbine has three aspects to it: speed of wind in the region of construction, type of rotors and, finally, there is the generator that converts the mechanical energy into electricity.
Wind turbines have very high requirements in terms of their placement. They are installed in plain fields and no relief is accepted. Every tree and every mountain decreases the kinetic energy of the wind (speed) and deviates some of this precious wind above the turbines. In fact, this is the reason for which turbines are so high. Perfectly smooth surfaces are impossible in the real world so turbines are lifted high above the ground to minimize the negative effects of the relief. Also, the region has to have almost constant wind. Not every field could be a wind farm. The minimum percentage of time the wind blows properly is 80%. And still 20% of time energy is not produced
The next aspect of a wind turbine is the turbine itself. Wind turbines are devised in two major groups: horizontal and vertical axis of rotation turbines. The horizontal axis of rotation is the most common. Horizontal axis means that the turbine rotates around an axis parallel to the ground just like a fan. The first type of horizontal turbines are the drag base turbines (rarely used on big wind turbines).
Those type of turbines were used in middle ages for wind mills. The idea is similar to the sails of a ship, but here the wind pushes the cloth in to the rotational movement. A more advanced technology is the lift turbines. Those work like wings of a plain. Blades are installed perpendicular to the wind. These types of blades have a side with a pronounced curve and a flat side. When the wind goes around the blade, the shape of the blade creates a depression on one side of itself and a higher pressure on the opposite side. The blade is then pushed in to the rotational movement in the direction of lower pressure. Lift wind turbines are very performing but also very noisy which is a big counter point in there installation.
The vertical axis turbines are rotating around an axis perpendicular to the ground. The majority of those type of turbines work on drag, but lift turbines also exist. The reason we don’t see this type of turbines is due to the lack of efficiency. Vertical axes are basically a turning cylinder with sails or wings. The problem with those is that when one side is pushed in one direction, the other one has to move against the wind back to the position of the first one. This even with the most performing turbines creates a loss of the mechanical energy. On the other hand, the advantage of those is that they make almost no noise. For this reason, you will commonly see them in towns.
The final step is to make electricity from the mechanical energy of rotation. This is the function of a generator. When a turbine starts to rotate, it rotates a solenoid wire made up of thousands of loops. This wire is installed between two powerful magnets of the generator, in other words. When the wire is rotating, the magnets start to move electrons in this wire (there is huge physical explanation which is a topic of its own). This displacement of electrons is basically electricity that we use in our daily life.
Wind turbines are an effective and a green way to produce energy, but they also have very high requirements in order for them to be actually useful. When choosing wind turbines, such aspects as energy needs relief and size have to be considered in order to use the proper type. If all of the above is applied properly, wind energy could answer to the majority of our electrical needs.
http://energy.gov/eere/wind/how-do-wind-turbines-work (Very easy and visual site that helps to understand how wind energy is produced)
http://www.turbinesinfo.com/types-of-wind-turbines/ (Advantages and disadvantages of each type of turbine are very well show here although some of them have very little importance for the general point)
http://www.turbinesinfo.com/horizontal-axis-wind-turbines-hawt/ (How a horizontal wind turbine works)
http://www.arborwind.com/aw-turbines/how-it-works/(How a vertical wind turbine works)
edited by: Julia Pabst-Leonidas