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The share of renewable energy in the German production of electricity has considerably increased in recent years. By 2020, 20 to 30 % of the electricity production will have to be covered by renewable energy. The offshore wind capacity has enormous energy potentials.

Electricity produced by offshore wind turbines can and should make an important contribution to Germany's future energy and climate policy. In order to make use of these potentials, the expansion of the grid infrastructure is essential. After all, the electricity volumes produced at sea have to be transported to the consumer. Submarine cables have to be built from scratch in order to connect offshore wind farms (OWF). The onshore power line grids also have to be expanded in order to transport the wind energy further on.

50Hertz is very committed to these tasks and provides its technical know-how in the interest of the energy mix of the future and of climate protection.

The biotope of the Baltic Sea

German coastal zones represent precious ecosystems. Coastal strips are an important biotope for many species. The high significance of coastal zones is reflected by the fact that wide coastal surfaces have already been turned into nature reserves.

The German exclusive economic zone (EEZ) of the Baltic Sea mainly consists of fine sands, where surfaces with over 20 % of mud represent about half of the total surface. Till is a very common sediment on the sea floor of the central and southern Baltic Sea. It is a glacial sediment. It has a grain diameter spectrum that ranges from clay over sand and gravel to rocks, including glacial detritus.

Some smaller surfaces are covered by rougher sands and gravel or screes. The latter are partially similar to reefs, which can reach several meters of diameter. The water depth in the German part of the EEZ reaches a maximum of 50 m, and decreases to less than 10 meter in its eastern areas. A characteristic of this zone are the stream channel areas of the Kadettrinne, some parts of which only have a thin layer of sediment. Similarly to the North Sea, the diversity of habitats in the Baltic Sea increases the closer one approaches the coasts.


In the Baltic Sea, the ecological conditions are different from the ones in the North Sea: it is the biggest brackish water area, which has evolved over the relatively short period of the past 12,000 years. While the salinity in the central Baltic Sea ranges between 15 and 25 per mill, it can be as low as 2 per mill in the north-eastern area. In contrast to the North Sea, the tides only change by centimetres; any noteworthy changes in the water level mainly occur due to the influence of the wind, and create mud flats.

In the past, it was not legally possible to establish nature reserves or surfaces appropriate for wind energy in the EEZ. This has changed with the entry into force of the amendment of the Federal Nature Conservation Act (BNatSchG) adopted by the German Bundestag. The EEZ sea areas were studied in order to identify the areas that are worth protecting. Charts with the proposed areas and with information on the dispersion of such animals as migratory birds and porpoises, or habitats in the North Sea and in the Baltic Sea are published on the Internet by the German Federal Office for Nature Conservation.

There is still insufficient knowledge that would allow us to assess the overall impact of offshore wind turbines and of the construction and operation of the corresponding submarine cables on the marine environment. Ultimately, the impact that offshore wind farms and their connection to the extra high voltage grid have on the marine environment and nature can only be assessed reliably when the first larger projects have been realised.


Christian Brehm

Public participation

Christian Brehm
Tel: +49 30 5150-3556
Fax: +49 30 5150-3112
E-Mail: christian.brehm@50hertz.com


Wind energy

German renewable energy producers are pioneers in the exploitation of wind power. Currently, more than 21,000 wind turbines with an installed capacity of approximately 26,000 megawatts are operational in Germany. Already today, 50Hertz feeds about 42 % of the installed wind power capacity in Germany into the grid. At the same time, the high wind-related fluctuations of the energy fed into the grid must be compensated.