Wind turbines use the kinetic energy of the incoming air. Modern wind power plants consist of a mast, a nacelle with the mechanical equipment, and the rotor, normally with three rotor blades. They start rotating at a wind speed of 2 metres per second (m/s). A wind power plant begins producing electricity from a wind speed of 4 m/s. The maximum power output is reached at 12 to 15 m/s. During storms, the wind turbine is usually switched off to prevent damage. The tips of the rotor blades can reach speeds exceeding 200 km/h. Electricity production depends on the wind speed (electricity production proportional to the third power of the wind speed). If the wind speed is doubled, 23 or 8 times more energy is produced.
The technology of wind turbines is relatively mature. However, there is still room for improvement, particularly in the areas of cost-effective design, production technology, overall efficiency and in operation and maintenance concepts, which result in lower production costs. The service life of a plant is between 20 and 25 years. The plant can then be repowered (replaced by a more modern, efficient plant) or dismantled. An average wind turbine consists of 60-65% concrete, 30-35% steel, 2-3% composite materials (e.g. glass fibre reinforced plastics) and less than 1% copper.
During its service life, a wind power plant generates about 40 times as much energy as was required for its manufacture, operation and disposal. The output of individual wind turbines has increased sharply over the past 25 years: Onshore (on land) from 0.5 MW to 7 MW. The choice of the power output and turbine tower height largely depends on the local wind conditions. Offshore (at sea) turbines have a capacity of 5 up to 14 MW.
The Haliade-X made by the US manufacturer General Electric is currently one of the most powerful wind turbine. It is able to generate around 45% more energy than any other offshore wind turbine currently available on the market. A 14-megawatt generator ensures this. As a result, offshore wind farms could operate with fewer individual turbines in the future. One of the first locations to use this wind turbine will be the port area of Rotterdam.
Axpo is Switzerland's largest producer of renewable energies. In addition to Swiss hydropower and biomass, we also use wind power at the best locations in Europe. The sustainable energy future has already begun at Axpo.
Volkswind has been a 100% subsidiary of Axpo since summer 2015. The German company has developed more than 80 wind farms in Germany and France with an installed capacity of over 1,350 MW. In France, Axpo is already one of the leading companies in the development and construction of wind energy plants.
Axpo aims to add a total of 3 gigawatts of capacity in Europe by 2030.
This means that Axpo is active across the entire value chain in the wind business: in addition to operating the plants and marketing electricity, Axpo's business model also includes the development, construction and sale of wind farms, as well as their management.
The Global Tech I wind farm has been generating electricity for around 445,000 households far out in the North Sea since September 2015 with 80 wind turbines of the 5 MW class. Axpo has a 24.1 percent interest in this offshore wind farm. Global Tech I was one of the first wind farms to be built in the German North Sea, and is one of the so-called "far offshore wind farms" owing to its location 140 kilometres north of the logistics base in Emden.
At a water depth of 38 to 41 metres, the wind turbines excluding the rotor reach a total height of around 132 metres from the seabed. As a result, the rotor hub is thus approximately 92 meters above sea Ievel. With its three blades, the rotor has a diameter of 116 metres and covers an area the size of one and a half football fields. The tips of the rotors can reach a maximum speed of 320 kilometres per hour making them nearly as fast as today's Formula 1 racing cars.
The wind turbines cover an area of 41 square kilometres, which is just over half the size of the city of Zurich. They begin turning at wind speeds as low as 4 metres per second. They produce their peak output at a wind speed of 12.5 metres per second (45 km/h). At wind speeds of 90 km/h and more they are shut off for safety reasons.
With this commitment, Axpo aims to further promote the creation of value from renewable energies in Europe.
In Switzerland, the Axpo subsidiary CKW (Centralschweizerische Kraftwerke AG) is committed to the wind business.
Since summer 2013, it has been operating a wind turbine with a gross capacity of 2.3 MW on the Lutersarni hill (Entlebuch). At 120 metres, it is about the same height as the Prime Tower in Zurich and produces electricity for the equivalent of 600 four-person households per year (around 2.5 million kWh).
Another wind project on the Lindenberg on the border between the cantons of Aargau and Lucerne, which is being realised jointly with AEW and SIG, is well advanced.
Six other wind farm projects in Central Switzerland and Aargau are in the planning stage. The potentially 20 or so turbines will one day produce clean electricity for over 30,000 households.
In addition to its involvement in plant construction and power production, Axpo is also a leading pan-European marketer of renewable energies. In total, Axpo markets approximately 19,700 megawatts of solar and wind energy on behalf of its customers. Through its use of pioneering long-term power purchase agreements (PPAs), Axpo has been able to ensure the broad and sustainable growth of renewable energies, supporting numerous corporate customers in some 40 markets to achieve lower CO2 emissions.
Rated output is the capacity of the wind turbine generator at full capacity measured in megawatt hours (MW). Wind turbines reach the rated output value at various wind speeds.
Onshore wind turbines are located on land and generate wind energy from mainland wind.
Offshore wind turbines benefit from the high wind speed at sea. They are located off coastal areas. Axpo holds interests in 80 turbines with a total capacity of 400 MW in the North Sea.
The site defines a coherent area suitable for the use of wind energy. The site offers space for at least 3 wind turbines.
Wind energy plant refers to the wind power plant or the wind turbine. The facility transforms the power of wind into electrical energy and feeds it into the power grid.
A wind power plant comprises the following elements:
The wind farm is an arrangement of three or more wind turbines at one location.
Switzerland is not a typical wind country. Nevertheless, the construction of a wind power plant can be interesting at individual locations. Although this does not provide predictable energy, relatively large amounts of electricity can be generated at economic prices with modern plants. In addition, investments in wind power are subsidised by the cost-covering feed-in tariff (KEV). Suitable sites for wind turbines are located on the Jura heights, but also in the foothills of the Alps and in the western Central Plateau.
There are currently 41 wind turbines in this country, producing around 144 GWh of electricity. The largest wind farm is located on Mont Croisin in the Bernese Jura near St. Imier. There, 16 turbines with a total output of 37.2 MW have been installed. There are other large plants in the Rhone Valley (VS), near Entlebuch (LU) and on the Gütsch above Andermatt (UR).
According to the Energy Strategy 2050+, wind turbines in Switzerland should generate up to 4.3 TWh of electricity from wind power by 2050.
However, the construction of wind turbines in Switzerland often meets with local resistance due to noise pollution or conflicts with nature conservation and landscape protection.
Map of all wind power plants: https://www.uvek-gis.admin.ch/BFE/storymaps/EE_WEA/index.php?lang=de
Federal wind atlas: https://www.uvek-gis.admin.ch/BFE/storymaps/EE_Windatlas/?lang=de