Wind farm

A wind farm is a collection of wind turbines (WT ). This can be organizationally ( by an investor or operator ) and technically form a unit (with a common supply of electric current ). Wind farms can be divided into the following types:

• " Grown " wind farms caused by the proximity successively erected plants.
• Planned wind farms for a collections of plants of a planner, manufacturer or operator that were built or planned in the course of a construction project. This includes later expansions with.
• On the other hand, there are officially designated areas for wind turbines. The aim here is to focus it in certain areas in order to relieve the rest of the landscape. For example, in 2011 wind power to 0.8 % of the area of Schleswig -Holstein was approved; the state government wants to expand to at least 1.5 %.

Wind farms can be built at sea (offshore) in the inland (onshore), on the coast ( nearshore ) or at a considerable distance from the coast. You can include only three, but also more than 100 wind turbines and provide a few MW up to 100 MW feed- lot. In some wind farms, only one type of plant is verwendt, but there are also wind farms in which several types of plant come, even from different manufacturers are used. By using wind turbines with hub heights varying the distance between the wind turbines can be increased at the same spatial extent of the wind farm, which the mutual influence reduced.

For wind farms often include wind measurement masts, either temporarily serve before the set up to forecast the yield or be permanently erected for purposes of meteorological research. In general, the yield is predicted over a wind assessment due to long-term data over several years or decades.

Onshore - Wind farms on land

Approval process

The Federal Administrative Court ( Federal Administrative Court ) decided in June 2004 that permit legally a collection of at least three wind turbines is considered Germany's wind farm, if they are " associated with each other spatially so that overlap their exposure areas or at least touch it. " These have then to the more expensive Federal Pollution Control Act ( Federal Pollution Control Act ) be approved, while otherwise only a building permit is mandatory. It is irrelevant whether the assets are to be considered assigned to multiple operators. In addition, single or "only two " systems must be approved by the Federal Pollution Control Act, when a plant reaches a total height of over 50 meters.

Financing

Wind farms were funded initially by either large individual investors or through project financing, in the form of the establishment of a closed-end fund. In a closed-end fund to bring more investors to the capital, which is supplemented by a bank loan. Since 2005, other forms, such as the leasing or the issue of bonus shares are possible. In addition, community wind parks have increasingly established, such as in the legal form of a cooperative, as an alternative financing option. Here the parties directly involved have a secure share of the profits and a lower economic risk. For the financing of large-scale offshore wind farms with a total investment to over one billion euros mostly large banks, multinational corporations, or consortia of such corporations come into question.

Planning

From the perspective of investors, it is an advantage that planning can be done from a single source: There is no need for each plant its own approval procedures are performed. On the other hand, a more elaborate procedure is required for the planning of wind farms.

To minimize the interference, the rotors must be positioned with a certain minimum distance from each other. This is mainly dependent on the system size and the prevailing wind direction. As a rule of thumb for wind farms on the coast was so far in the main wind direction five times, in addition to wind direction three times the rotor diameter as the minimum distance.

However, in large wind farms the turbulence behavior of the rotors on the position of individual plants depends. According to recent studies, the optimal efficiency is achieved only at about 15 times the rotor spacing. Researchers at the Johns Hopkins University were using simulations to the conclusion that a chessboard placed wind turbines is not advantageous structure in large wind farms. They organize offset in blocks reducing the yield by reducing the wind turbulence between the wind turbines.

Construction

In the construction of wind farms planned in a course, the investor has the advantage that the entire infrastructure can be concentrated. Equipment, cranes and access roads can be used the same for multiple installations. So do not be disarmed about the large crawler cranes to drive of a wind power plant to the next. If, during the construction of a plant to delays, so can be used at this time at another facility.

In wind farms, the systems must be provided with an obstacle marking. These include the color coding of the rotor blade tips and the lights in poor visibility. Within a wind farm flashing or blinking of the lights will be synchronized via the DCF77 time signal at the new park. In part, this is retrofitted to older parks.

Operation

All wind turbines of a wind farm appear as a single power plant for electricity network operators ( utilities ); simplifies and cheapens example, the feed bill for the operator of the wind farm. The control of a wind farm is carried out centrally for the entire wind farm. Each resort also has also its own control. As a grown wind farm sometimes composed of different types of wind turbines that make different demands on the wind speed, it may occur that individual wind turbines are shut down due to the wind conditions.

The plant maintenance can be concentrated performed at several plants. Large travel distances and times for technicians account. Experience shows that the longer residence time of maintenance technicians also increases the likelihood that a technician if a system fault on the spot ( the wind farm ). The reaction times are shortened.

Yield losses due to shading ( WAKE- losses)

Wind turbines can negatively affect each other by participating in certain wind directions mutually aerodynamically " shade " ( lee, WAKE or caster). What are these losses is controversial. An attempt is made to be held by a Abschattungsanalyse, these losses as low as possible. In floating wind turbines, there are plans by multiple systems or local relocation to avoid or minimize these losses.

Network problems

As the existing power grid has only been partially adjusted to the strong development of wind parks, it may va during periods of high wind power generation come in northern and eastern Germany to local energy surplus, which may result by the network operator to a limitation of the energy supplied. This went in 2011 about 407 gigawatt hours ( GWh) of wind power lost just under 1 % of the actual fed wind power generation of about 48,900 GWh. Since the operators must be compensated largely for such reductions in production, develop the current customer loads in the expected amount of 18-35 million euros for this not injected current.

Lately the temperatures and wind speeds are measured at the overhead lines, as both factors influence the capacity of an existing overhead line ( lower temperatures and higher wind speeds have a positive effect ). In the Dena Grid Study beyond the necessary adjustments were considered associated with the planned offshore wind farms. From the perspective of a power system operator virtual power plants must be connected to the electricity grid at a great distance to the consumer here, which leads to significant investments.

Experimental wind farms

There are also wind farms, where the testing and measuring of wind turbines in the foreground. In such wind farms in general, from any type of system exists only a single specimen, which belongs to the manufacturing company. To measure the wind speed is in such wind farms at least one wind measurement tower. One such attempt is the wind farm wind turbine test field Østerild.

List of wind farms

List of the largest wind farms

List of the largest wind farms ( under construction)

List of the largest wind farms ( in planning)

Offshore wind farms

The term offshore wind farm is used for wind farms, whose foundations are in the lake. There, the continuously occurring wind to be used. Wind farms are so far not built on " the high seas ", but only on the continental shelf.

In 2002 went to Denmark with Horns Rev 1 of the then largest offshore wind farm in the world connected to the grid: There are 80 wind turbines in the North Sea. They annually produce 600 GWh of energy, enough for 150,000 Danish households.

Currently, the largest offshore wind farm in the world is the London Array with 630 MW total capacity (as of May 2013).

Environmental impact

Like all types of energy have wind farms impact on the environment. Recent detailed studies showed that in collisions of birds and bats with wind turbines the respective species were extremely affected differently. A total of 732 vultures were killed in 140 wind farms in northern Spain with a total of 4083 wind turbines in 2000-2006 found ( current stock: well over 20,000 pairs). In a test in the fall of 2006, a wind turbine in Denmark was monitored a total of 2,400 hours. Here, 15 birds and bats were discovered who came near him, and there was only a single collision with a bat. The wind turbine was in one of the busiest flying sites. The behavior of marine mammals, water birds and fish shows no negative changes.

According to a study by the Massachusetts Institute of Technology in 2009 it can be assumed that would be expected with significant climate effects when 10% of the energy required would be covered by wind power worldwide. While on and in the vicinity of wind farms on land would be expected with a warming of about one Kelvin, was assumed for wind parks at sea by an opposite effect.

Examples of particular wind farms

• The world's most powerful wind farm in January 2013, the Alta Wind Energy Center in Kern County, California (USA) with an installed capacity of 1320 MW and 490 plants.
• The largest wind farm with the most individual plants in the world is the Roscoe Wind Farm near the same place in Nolan County, Texas (USA). It consists of 627 wind turbines with a total capacity of 781.5 MW and was at the time of its completion in 2009, the most powerful wind farm in the world.
• The largest and most powerful offshore wind farm is a world in January 2013, the London Array in the North Sea at the Thames Estuary, with an installed capacity of 630 MW and 175 plants.
• The largest planned wind farm is the Dogger Bank wind farm with 1500 wind turbines with a total rated output of approximately 9000 MW. This corresponds to the nominal output of about 7 nuclear power plants. The annual energy yield equivalent to about 4-5 nuclear power plants during postulated 4000-4500 full load hours for wind turbines and 7500-8000 full load hours for the nuclear power plants.
• The first wind farm in Europe was taken in 1982 on the Cycladic island of Kythnos in operation, consisting of five wind turbines with a total output of 100 kW. The facility replaced the supply by a diesel power plant. In 1983, a solar system in the supply concept " island model Kythnos " was involved.
• The largest ( under construction ) onshore wind farm in Europe is the sine Holding wind farm near Vaslui in Romania, which consists of a cluster of five adjacent wind farms and is expected to reach a total capacity of 700 MW with a total of 350 individual plants.
• The highest wind park in Europe is on the Gütsch near Andermatt on 2331 m above sea level. M. It has three plants with a total of 2.4 MW.
• The first wind farm in Germany, the wind farm west coast in the Kaiser -Wilhelm- polder at the Schleswig -Holstein North Sea coast, was put into operation on 24 August 1987.
• The first German wind farm in the highlands was the wind energy park Vogelsberg at Hartmannshain in Hesse, which went into operation in November 1990.
• The first German offshore wind farm alpha ventus was in the North Sea northwest of Borkum, which is fully in operation since late 2009.
• In the wind farm Holtriem in East Friesland and in the euro wind farm Vetschau at Aachen, a wind energy plant with a viewing platform height 60 m are each equipped.
• The wind farm Estinnes in Belgium comprises eleven Enercon E- 126, with up to 7.5 MW at present ( June 2012) most powerful wind turbine in the world.