BBI Zeneris

The wind effect is mainly a consequence of unevenly heated by the sun masses of air, uneven surface of the Earth and rotation of the globe. Wind turbines convert kinetic energy in wind into mechanical energy that can be used for specific purposes (e.g. pumping water) or, with the use of power generator, for generation of electricity.

Modern wind turbines can be classified into two main groups: turbines with horizontal and vertical axis of operation. Nowadays, the most common are turbines with horizontal axis and two or three blades. Machines of that type are further classified into two subgroups: upwind and downwind turbines, pointing upwind or downwind.

The power of a single turbine varies from 50kW up to several MW (one of the largest machines of that type is GE turbine of 3.6 MW power). Large turbines are frequently grouped into the so-called wind farms, creating a modular wind power station with a capacity ranging from several dozen up to several hundred MW.

Small turbines producing up to 50kW of power or less are most often used for generating energy for household purposes, pumping water etc. Sometimes they operate in combination with diesel generators, photo-voltaic cells or modules creating so-called hybrid systems used to supply power in areas where, for various reasons, the grid is inaccessible.

A typical wind turbine is composed of the following elements:

• Anemometer measuring the velocity of wind and transmitting data to the controller;

• Turbine blades – most turbines have two or three profiled blades. Wind hits the blades, creates differential pressure on their surface and moves them; the movement is translated into the rotary motion of the shaft;

• Shut-down system used to stop the machine in case of emergency (e.g. breakdown);

• Controller – a device starting the turbine when the minimal velocity of the wind ranges from 8 to 16mph and stopping it when the speed exceeds 65mph. The turbines cannot operate under stronger winds due to generator overheating hazard;

• Gear-box connecting a low-speed shaft (connected directly to the blades of the turbine) to a high-speed shaft (connected to the generator). It increases the rotation speed from 30-60 revolutions per minute up to 1200-1500 revolutions per minute. One of the most heavy and expensive components of a wind turbine.

• Power generator that generates electricity;

• Blade positioning system responsible for the optimum positioning of blades towards wind;

• Tower, being the load bearing element of the turbine. As the force of wind increases with height, generally speaking the higher a tower the more electricity it can produce.

Advantages of wind as a source of energy:

 

• Wind is a clean source of power, i.e. the production of wind-based energy does not pollute the air and does not result in the emission of greenhouse gases; etc.;

• Wind is a local source of energy, production of wind-based power increases the power safety of a country;

• Wind is the so-called renewable source of energy, i.e. a source that cannot be depleted;

• Wind is one of the cheapest renewable sources of energy.

Disadvantages of wind as a source of energy:

 

• Power generated from this source must be competitive in price to power produced from other sources (including traditional ones). A wind farm will be or will not be competitive depending on weather conditions throughout the year. Even though lately the costs of installation of wind power plants have been significantly reduced and the turbine efficiency has increased, investments are still very expensive, in particular when compared to investments in machinery producing power from traditional sources;

• The production of electricity from wind, is based on uncontrolled, natural phenomenon, which results in problems with synchronizing the production and the demand for power;

• In practice, the best conditions for wind farms are in remote spots, located far away from agglomerations, resulting in additional costs related with the need to transmit electrical energy over long distances;

• Even though the production of electricity from wind has a relatively small impact on the environment, it is not totally neutral. Some of negative effects include: noise generated by the rotating blades, disruption of the appearance of the landscape, frequent collisions of birds with the blades.

Wind power production history

The first recorded use of wind power by men dates back to 5000 BC. Wind powered boats that transported people along the River Nil. Around 200 years before Christ, simple machines were working in China with the use of wind energy to pump water, while in Persia and in the Middle East, wind was used to power grinding machines. Until the 11th century, wind-driven machines were widely used in the Middle East, mainly for the production of food. The machines were brought to Europe by traders and crusaders.
During the Industrial Revolution, windmills used for pumping water or grinding flour were gradually supplanted by steam engines and later by electricity. After some time, the largest windmills were adapted for the production of electricity. The first machines of that type were built in Denmark in 1890. In 1940, the first 1.25 MW turbine was installed.
The popularity of wind as a source of energy has always been correlated with prices of fossil fuels. After the Second World War, the interest in wind turbines decreased and regained popularity in the 1970s together with the fuel crisis and the sudden raise in oil prices in the world markets.

Wind power industry in Poland and Europe

With 8,754 MW of total installed capacity at the end of 2001, Germany is a leading producer of electricity from wind. 46% of the European and 34% of the world’s capacity of wind turbines is located there. In the next few years, the wind power industry is expected to develop further, in particular in the sea.
The growth dynamics of the wind power industry across the globe has not been reflected in the Polish power market. Despite quite significant wind power resources in Poland, the majority of numerous constructional, technological and location projects did not go beyond the initial design phase. The best wind conditions in Poland are observed in the Zachodniopomorskie and Pomorskie Province, it the south of the country and in the Suwałki region.
At present, there are about 40 professional wind power plants operating in Poland, selling electricity to the grid. Zagórze, Cisowo and Barzowice are three largest wind farms with a total capacity reaching 60 MW.