Wind Energy

Wind is created because of the pressure differences in the atmospfere. The wind grows stronger as the difference in pressure increases. Local weather systems are often caused by differences in the heating of the Earth’s surface by the Sun. When the Sun heats the Earth’s surface, the air close to the surface is heated an rises and the wind starts to blow. If the air rises high enough, it will be cooled to such an extent that it may form clouds.

            To convert the kinetic energy of the wind the blades of a turbine are shaped as an airfoil. The wind passing this airfoil produces aerodynamic force.

The power from a wind turbine is obtained by converting the force with which the wind blows into torque acting on the rotor blades. The rotor is connected to generator which transforms the rotation of the blades into electricity. Usually individual wind turbines are interconnected with a medium voltage network system. This system is then connected with the high voltage power grid thru a transformer.

The amount of power obtained through this method depends on various factors: density of the air, rotor area, wind speed etc. The wind speed is extremely important for the amount of energy a wind turbine can convert into electricity. The landscape has also a significant effect on the features of the wind. The more uneven the landscape, the more unstable the wind. This means taking into account large-scale formation with mountains and valleys, and also small-scale unevenness of the landscape.

            The first windmills were used to grind grain and pump water. In Europe they were build around 1100. In the year 1887, inventor Charles F. Brush built the first windmill intended to generate electricity. In the last 20 years turbines have increased power by a factor of 100 and the cost of energy has been reduced. The engineering base and computational tools have developed to match machine size and volume. Many technical challenges remain and more achievements will result.