Energy

Wind energy

Very long ago the human being thought about how to use the wind energy seeing the destructions that storms and hurricanes can bring.

Even in Ancient Egypt 3,5 thousands years B.C. wind engines were applied for water lifting and grain grinding.

For more than 50 centuries the appearance of windmills almost didn’t change. For example in England there is a windmill built in the middle of XVII century. Despite its advanced years it operates without fail even to the present day. In Russia before revolution there was about 250 thousands of windmills, with total capacity amounted to 1,5 million kilo-watt. Up to 3 milliard puds of grain was milled there. Wind mills with wings-sails made of textile first were constructed by the ancient Persians more than 1,5 thousand years ago. In the following windmills were being improved. In Europe they didn’t only grind flour but also pumped out water, worked butter, as for example in Holland. The first electro wind generator was constructed in Denmark in 1890 year. After 20 years there hundred similar installations worked.

The appearance of wind mills made one of the most hard labor of peasants easier – turning heavy millstones that grinded grain into flour. For the time being that made the wind, turning the wings of the mill. One of the first windmills was found in Persia – its wings were put on the same axis as the millstones. The Persian mill could be good in everything if it worked under any kind of wind – not only a stable strong one. When flows fell the millstones were being turned the same old way with the help of bulls or even slaves. So about 600 years ago building of turret-type mills with huge wings, situated horizontally to the earth surface, began.

Firstly one of such mills appeared in Holland, always being famous for inventive engineers. In 1745 year one Edmund Ly made millers happy having invented a new type of wings – wood frames covered with textile. The invention turned out to be so successful that is being applied in windmills even today.

Windmills turned out to be excellent sources of free energy. No wonder that in time they were used not only for grain grinding.

Wind mills turned slitting milling cutters at large timber mills, lifted cargo to upper altitudes, were used for water lifting. Along with watermills they were in fact the most powerful machines of the past. For example in Holland there were constructed windmills that successfully operated till the middle of our century. Some of them operate even today.

It is of interest that in the Middle Ages even the simplest labour-saving devices appeared to be so unusual that mills accused some hobgoblin terrors. Millers supposed to get in touch with evil spirit. Time passed and people thought about the wind as a free energy source more often. A new stage of technology development began - the stage of electric generators construction. The first wind generator for energy production was built in Denmark in 1890 year. Such wind generators were installed in hard-to-reach places where it was difficult or non-profitable to transfer current from common electrical generating stations. Finally wind turbines began to produce a quarter of all energy that Danish industry needed. In the period between 1920 and 1930 years wind generators began to appear in Australia and the USA. As it was told the biggest wind electrical generating station was built in the Crimea in 1937 year. Its size was really big but the capacity of produced current that was transferred to the electric power line of Sevastopol did exceed 100 kilo watt.

Wind energy is great. Its world stores according to the World Meteorological Organizations estimates reach 170 trillion kilo watt/hour per year. This energy can be produced avoiding pollution. However wind has two essential disadvantages: its energy is diffused in space greatly and it is unpredictable – it often changes its direction, suddenly it dies even in the windiest areas of the Earth or sometimes is so strong that breaks the windmills. Building, upkeep, repair of the wind installations working day-and-night outdoor in any weather is not cheap. Wind power station should occupy much more space in comparison with HPP, TPP or NPP although they have equal capacity. Besides wind power stations are not harmless: they disturb birds and insects flying, make noise, and reflect radio waves by turning blades and clutter broadcasting in the nearby communities. Who would like to live in a city where windmills roar on every roof? Such future city was described in the novel written by Herbert Wells “When the sleeper wakes” (1899 year). Different constructions are applied for producing wind energy: multi blade “chamomile”; external screws similar to airborne propelling screws with three, two or even one blade (than it has a counterbalance weight); vertical rotors, reminding a pipe cut longitudinally and put on an axis; certain similarity “staring” helicopters external screw; its outside ends of its blades are turned up and connected with each other.

Vertical constructions are good due to the detecting different directions of wind, the rest need to turn by the wind. There are also quite original decisions – for example a truck with a sail goes by circle of metals and its wheels activate the electric generator.

An installation creating the wind itself operated for a long time in Spain. A very high pipe (chimney) was constructed there. A wide area of ground around its basis was covered with polyethylene film fixed on frame piers. The ground and air were heated under hot Spanish sun and constant equal draft appeared in the pipe. A blade wheel built in the chimney turned the generator. The draft stops neither cloudy day (if the glum was not too turbid) nor at night: the ground saves the heat for a long time. However the exploitation of such installation was rather expensive: the metal pipe stained step by step and the film perished. Bad weather was also very harmful for the wind energy station…After a next hurricane it was decided not to repair the pipe. In order to compensate instability of the wind huge “wind farms” were constructed. Wind engines are installed there in rows on a large area and operate for one main. The wind can blow on one side of the “farm” while it is windless on the other side. Wind installations can’t be installed very close to each other in order not to shadow each other. That why this “farm” occupies much space. Such “farms” are constructed in the USA, France, England, and in Denmark “wind farm” was situated in the nearshore shallow waters of the North Sea where it disturbs nobody and the wind is more stable there than on the land. In order to decrease the dependence of inconstant direction and power of the wind, flywheels and various accumulators are installed in the system. They partly smooth blasts of the wind. Common they are electrical ones. However air and hydraulic flywheels and accumulators are applied. If an air device is used the wind installation pumps air in balloons; coming out straight stream turns the turbine with electrical generator. If a hydraulic one is used under wind power water is lifted at a certain altitude and when it falls down it turns the turbine. Electrolytic accumulators are also installed. The wind energy station produces the electricity that decomposes water to hydrogen and oxygen. They are kept in balloons and as needed are burnt in fuel cell (i.e. in chemical reactor where energy of fuel transforms into electricity) or in a gas turbine and again receiving current but without violent oscillatory motion of voltage according to winds’ “mood”.

Russian scientist Joukowski N.E. (1847-1921) the founder of today aerodynamics calculated theoretic degree of efficiency of a wind engine. It appeared to be rather high – about 60%. But in reality it is 10-15% less. More than 30 thousand wind energy stations of different efficiency work nowadays all over the world. Germany receives 10% of whole electric energy thanks to the wind, and all over Eastern Europe wind produces 2500 Mw of electrical energy. As the wind power stations become self-liquidated and there constructions are being developed, the price for the “air” electricity is being reduced. So in France by 2000 year in comparison with 1993 year it decreased in 1,5 times. What does obstruct the widespread use of the wind? Essentially there are two of them: nonconstancy of its direction and necessity of energy accumulation in case of wind absence or its low power. Apparently wind energy stations are considered to be one of the ways of extra energy production that allows reducing the expenditure of organic fuel.

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