The turning motion of our planet and the influence of solar radiation cause the regular air circulation over the sea and land. The technically exploitable potential of the wind’s energy is appraised to 26.000 TWh a year.

People soon realized, that they could use the wind energy. Wind was most probably the first element curbed by man. It is possible to support, that Egyptians used the power of wind as their boats´ drive 5.000 years B.C.

But the first practically used machines were the windmills. In China and Persia they had been used since the 7th century. In the 10th century Arabs bring them to Spain. During the 12th and 13th century they expand to the other European countries. The importance of wind energy culminated in the 16th century. In the 17th century there were about 60.000 windmills. In Bohemia, Silesia and Moravia the wind energy had been used since the 18th and 19th century. About 260 partly plotted localities prove, that there used to stay windmills. For Holland they are just as typical as tulips. Only on the river Zaan (north-west from Amsterdam) there were more than 700 of them. On the contrary of England and Germany, where the main energy source was coal, in Holland the wind machines answered this need. In 1850 the total energy output of all windmills cold be about 1.000 MW.

Just as its name suggests, these machines were used for corn grinding. But the same method was even used for sugar cane processing and for pumping of water. The first man, who was seriously concerned in electricity production with the help of air, was Paul la Cour (1846 – 1908). Most probably he also created the first air engine, which produced electricity current. It happened in the year 1891 and he used the produced current for electrolysis in his school.

All these air engines worked on the principle of resistance: wind is flowing on the vane (e.g. a flat desk), this vane puts up resistance and so power appears and turns the rotor. The effectiveness of such an engine is very low and it doesn’t even reach 20 %. This fact contributed to the construction of wind engines working on the principles of buoyancy. The wind flows round the vane, which looks like an air propeller (wing).

The effectiveness of such a wind engine can exceed 50 %. The vanes´speed must exceed the speed of the wind many times. Only upon this condition the wind energy can be used. At the same time, the smaller the number of vanes is, the higher is the high-speed coefficient (the rate of the vanes´ peripheral speed and the speed of the wind) and the quicker the rotor turns. Therefore the wind stations have only one, two or three wings.

(picture from web page
http://www.ems.psu.edu/info/explore/WindEner.html)

Such constructions started to appear during the WW2 and their building culminated in the 50´s when they appeared in many world’s countries. Another part of wind engines´ history came about in the 80´s in California. There, in the San Gorgonio pass, one of the first wind farms with 3.500 turbines was built. This farm is still working. Later the next “farms” were built. Their output differs a lot, from a few hundreds of kW in the small farms up to the great ones (e.g. in the pass Tehachapi). This pass belongs to the most windy places on the planet and therefore this power station produces 1,3 TWH a year (1.300.000.000 kWh)! Some of the smaller ones are also in Europe (Great Britain).

Wind power station in California, Tehachapi
(picture from web page http://rotor.fb12.tu-berlin.de/windfarm/tehcal.html)

To allow the rotor to take over as much wind energy as possible, the “head” of the power station (so called gondola) is fixed to the pole in a turning way. The windmill uses a side wind wheel or an electric motor too adjust the rotor’s axis with the air’s direction. This disadvantage is balanced with the wind engines´ construction: the wind engines have a vertical axis of turning. This machinery was publicized by a French George J. Darreius in 1930. But nobody could see the importance in it. But at the beginning of the 70´s when the energetic crises came, the Darius system was reinvented. Of course, its form corresponded with the technology of that time. The vertical rotor usually had two or three vanes, in its traverse cut they were shaped as an air profile. The next advantage of this system was the fact, that the expensive construction of the turning gondola is not necessary anymore, and that the generator is placed on the earth, so that is can be maintained easily. An electric motor was necessary for setting it going.

Our republic does not have such good conditions for the use of wind energy as e.g. California or the seaside states. But even though every investment, which makes the production of electric power possible and which saves tones of sulphurous oxide, nitrogen oxide, carbonic oxide or fly-ash is a good investment.

The number of wind power stations is increasing satisfyingly. In United States the total installed output of these power stations is 1.700 MW, in Denmark 520 MW, in Germany 330 MW. During the last ten years more than 20.000 of them were built, even though the use of these power station is rather low. (The above mentioned 50 % effectiveness, is the effectiveness of the whole machinery. But if we take into account the fact, that the activity and the output of a power station depends on the right wind’s intensity then the effectiveness sinks up to 12 – 16 %). This fact causes an unfavourable rate between the purchase price, operation costs and the produced kWh.

"Home" wind power station A.V.E.E. Hranice
(diameter of the wings 10 m, effort 11 kW)