Deutsche Bucht — Renewable energy from the North Sea

WIND FARM

The Deutsche Bucht offshore wind farm is located over 100 kilometres from the German mainland, approximately 95 kilometres North-West of the island of Borkum. This project occupies an area of 22.6 square kilometres and comprises 33 MHI Vestas wind turbines of type V164-8.4 MW and a proprietary offshore substation. Two of these turbines have been installed for the first time on Mono Buckets as a pilot project. To test this foundation, the Federal Grid Agency (BNetzA) assigned the Deutsche Bucht wind farm 16.8 megawatts of additional grid connection capacity. After its scheduled commissioning at the end of 2019, Deutsche Bucht will have a grid connection capacity of 268,8 megawatts, meaning that it will meet the annual energy needs of approximately 328,000 households.

Deutsche Bucht is the third offshore wind project of Canadian energy company Northland Power in the North Sea. Construction is expected to start in the summer of 2018. 

Location

Various factors played a role in the site selection for this wind farm on the high seas. The area where Deutsche Bucht is located is characterised by consistently favourable North Sea wind conditions. In addition, the project is ideally sited to minimize impacts on the environment, shipping and tourism. More

The Deutsche Bucht wind farm is located over 100 kilometres from the German mainland. It lies in the German Exclusive Economic Zone, an area explicitly designated for economic development in the North Sea. The location offers optimal conditions for generating electricity, with consistently good wind conditions, and an average wind speed of around 10 metres per second. The depth of the water is around 40 metres.

As well as the wind speed and the constant winds, protection of the marine environment also played a significant role in the site selection. Deutsche Bucht is located some distance from the Wadden Sea National Park. Read more on environmental protection.

The safety of maritime traffic was also a major factor in site selection. The project location is far from the much-travelled shipping routes, which are therefore unaffected. The distance from the mainland is also an advantage for tourism: The North Sea power station cannot be seen from the shore.

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Economic areas for offshore wind

The Exclusive Economic Zone (EEZ) is an area of sea which can be utilized for economic purposes by the country adjacent to it. It extends up to 200 nautical miles outwards from a country’s territorial waters, the so-called 12 nautical mile zone. According to the Federal Spatial Offshore Grid Plan, the area of Deutsche Bucht lies in Cluster 6. It has been explicitly designated an area for economic development by the Federal Maritime and Hydrographic Agency of Germany (BSH). This segmentation is necessary to balance social, economic and ecological demands. National and international legal requirements pertaining to marine environmental protection as well as German environmental protection targets were all taken into consideration. For example, on the one hand, care is taken to ensure that interference with the marine environment remains as low as possible. On the other hand, expanding the use of offshore wind power can contribute towards sustainable energy supplies and the attainment of climate goals, including those of the German government. The BSH publishes details on this on its website.

Size & Power

Due to the consistently high wind speeds and large turbines, offshore wind farms generate significantly more electricity than wind turbines on land. The Deutsche Bucht wind farm will use 8.4 megawatt turbines. With strong wind conditions, this means that more than 328,000 households can be supplied with renewable energy every year. More

The Deutsche Bucht wind farm will install 33 MHI Vestas turbines of type V164-8.0 MW. With its power mode, this particularly powerful type of turbine has a rated output of 8.4 megawatts. With a grid connection capacity of almost 269 megawatts, Deutsche Bucht can produce up to 1.1 billion kilowatt hours of renewable energy a year, enough to supply more than 328,000 households with an average electricity consumption of 3,440 kilowatt hours. You can find more information on the environmental benefits here.

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Grid Connection

The wind power from Deutsche Bucht will be converted to direct current by the transmission system operator to ensure that it reaches land with minimal loss. Use of the existing BorWin 2 grid connection will ensure a reliable connection to the German power grid. More

The transmission system operator TenneT  will be responsible for connecting the Deutsche Bucht wind farm to the German power grid. It  will collect the three-phase current from the offshore substation of the North Sea wind farm and transfer it to the BorWin beta converter station via two export cables.

The BorWin beta offshore converter station has been in operation since 2015, and by converting the three-phase current generated into direct current, it ensures that the electricity is brought to land with minimal loss. The onshore converter station in Diele converts the power back and feeds it into the German power grid. The direct current cable between the two converter stations runs for 125 kilometres through the North Sea and 75 kilometres overland.

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Protecting the North Sea

Construction of the Deutsche Bucht offshore wind farm is subject to strict regulations and laws. The aim is to make it as environmentally friendly as possible. Sophisticated technology is therefore used to erect the turbines. Possible effects on the environment are continuously measured and monitored throughout development, construction and operations. More

Protection of the marine environment plays a major role throughout the project’s lifecycle, beginning with site selection. For example, the Deutsche Bucht wind farm is located at a distance of over 100 kilometres from the coast, in an area  which is designated for economic development and far removed from the Wadden Sea National Park.

The environmental impact assessment (EIA) plays a major role in the approval process, i.e. before permission is granted to build a wind farm. The EIA includes a detailed survey of the fauna and flora in the area of the wind farm. In carrying out this initial survey, the wind farm developers have to determine exactly which species among the so-called “protected assets of the marine environment” are to be found on the site, and their populations. This includes birds, fish, marine mammals such as porpoises and grey seals, as well as life on the ocean floor. Based on the survey data, a forecast of the possible impact of the wind farm is produced. Approval of the project   is only granted if the EIA leads to a positive result, meaning that the wind farm can be built in an environmentally-friendly manner.

The approval authority for the German Exclusive Economic Zone, the Federal Maritime and Hydrographic Agency of Germany (BSH), has defined the scope of the examination in its standard examination concept “Investigation of the Impacts of Offshore Wind Turbines on the Marine Environment (StUK 4)”. The survey also serves as the basis for monitoring the environment. During the construction and operating phase of the wind farm, the fauna and flora are examined in detail several times at defined intervals to enable any potential impact to be identified.

In addition to studies on the environmental impact, detailed concepts on soundproofing while the foundations are laid must be presented and implemented. Among marine mammals, porpoises, which are a protected species, are considered to be particularly sensitive to noise. As they use their hearing to take their bearings, special rules apply for their protection in German waters: during the noise-intensive work to install the monopiles, the noise level must not exceed 160 decibels within a radius of 750 metres from the building site. A combination of two proven technologies is therefore used as part of the noise mitigation concept on the Deutsche Bucht wind farm: a hydro sound damper and a double Big Bubble Curtain.

The hydro sound damper (HSD) is a net which is placed around the monopile and lowered to the sea floor. Various foam elements (HSD elements) are fitted to the net; they dampen the underwater noise at different frequencies during the noise-intensive work. A double Big Bubble Curtain is also deployed. For this, two long hoses with holes several hundred metres in length are laid in a circle around the entire monopile building site and the installation vessel. Compressors pump air into both hoses with the result that air bubbles are released and travel upwards. This double bubble curtain stops the sound from propagating. The combination of these two systems, HSD and bubble curtain, is ideal, as a wide frequency range of sound waves can be absorbed due to their different effects. The efficacy of the soundproofing systems is reviewed as part of an efficiency check.

Deutsche Bucht is the first commercial wind farm to test so-called Mono Buckets as a type of foundation for two additional turbines. With this technique, the foundations are anchored in the ground by a suction effect. This installation method is quiet and does not require additional soundproofing systems. This type of foundation can also be completely dismantled at a later date. More

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Environmental study on porpoise population

As early as 2014,  the three research companies and institutes, BioConsult SH, IBL Umweltplanung and Institut für Angewandte Ökosystemforschung GmbH (IfAÖ) studied the impact of ramming noise on porpoises in the German Exclusive Economic Zone. In a comprehensive study covering the period from 2009 to 2013, they evaluated the data from eight offshore wind farms, with a total of 400 foundations. The study shows that offshore wind farms have no negative consequences for the porpoise population in the North Sea. During the direct pile-driving with soundproofing measures, the animals showed a short-term avoidance reaction. This means they stayed away from the area during the noise-intensive work, for a distance of up to 14 kilometres. Overall, the porpoise population in the North Sea remained constant, in spite of a steady increase in foundation work.

Press release and study results:   "Effects of offshore pile driving on harbour porpoise abundance in the German Bight. Assessment of Noise Effects.“

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