Ostwind 4

The submarine cable will cover a distance of 110 km, from the offshore converter platform in the O-2.2 wind farm area to the landing point at the coast near the port of Vierow. From there on, a 4-km underground cable system will run across land up to the Stllow substation.

Offshore route

The submarine cable system shall be laid along a route that runs as parallel as possible to the existing cables of the Ostwind 1, 2 and 3 projects to minimise the impact on nature.

The 525-kV HVDC submarine cable transports the wind farm’s electricity from the EEZ through the coastal waters and the Bay of Greifswald to the so-called landing point in the Vierow port area. The port is located in the municipality of Brünzow in the Vorpommern-Greifswald district of the state of Mecklenburg-Western Pomerania.

Onshore route

From the landing point, the electricity generated at sea shall be transported to the onshore converter at the Stilow substation by means of an underground land cable of around 4 km in length. The conduits into which the cables of the Ostwind 4 system will be pulled later on are laid as part of the same construction measure as the Ostwind 3 grid connection system. For this reason, the cable conduits were already included in the permitting procedure for the Ostwind 3 project.

The route of the underground cable section was checked against various interests and criteria during the preparation of the Ostwind 3 permitting procedure. For example, it should run as straight as possible and maintain certain distances to residential areas. Sensitive natural environments, such as Natura 2000 areas, nature conservation areas or forests shall be bypassed.

Onshore converter and substation

For the onshore grid connection, 50Hertz is planning a new converter in the area of the municipality of Brünzow to convert the direct current of the HVDC line into alternating current, which is then fed into the transmission grid. Provided that the permit is obtained, the converter shall be built in Stilow next to the planned substation of the Ostwind 3 project.

In the scope of the permitting procedure for the Ostwind 3 system, an extensive and meticulous site survey was carried out, based on various criteria. If possible, the site of the substation should be located outside of nature conservation areas and drinking water protection zones. The distance to residential and settlement areas shall also be taken into account. The traffic connection of the substation shall also be possible via suitable streets and rails. Moreover, the existing 50Hertz extra high-voltage grid, in this case a 380-kV overhead line, shall also be nearby, so that the substation can be connected to the power grid.

The converter as well as the expansion of the substation to connect the Ostwind 4 system to the Stilow site are part of the Ostwind 4 permitting procedure.

Ostwind 4 was first identified in the 2035 Grid Development Plan (GDP) of 2021 and was confirmed in the second draft of the 2037/2045 GDP of 2023 within the Baltic Sea offshore expanded grid. The 2023 area development plan (Flächenentwicklungsplan, FEP) laid down Ostwind 4, designated as OST-2-4, with a transmission capacity of 2,000 megawatts (MW). The project is intended to connect an offshore wind farm in the O-2.2 area. Furthermore, it takes account of development potentials for future additional transmission capacities.

Construction, expansion and conversion of electricity lines are infrastructural measures that affect many interested parties, like building development, agriculture and nature conservation. In order to fairly balance the many interests involved, the legislator planned and legally arranged the performance of a permitting procedure.

Ostwind 4 is expected to be approved in the three planning approval procedures (PFVs) or permitting procedures (EEZ, coastal waters of Mecklenburg-Western Pomerania and on shore).

Approval for EEZ and offshore converter platform

The alternating current generated at sea in the offshore wind farm is bundled on the offshore converter platform, converted into direct current and transported to the mainland by means of 525-kV HVDC submarine cables. The submarine cable runs through the areas of competence of different planning approval authorities. The Federal Maritime and Hydrographic Agency (BSH) is the competent planning approval authority for the permitting of offshore connecting lines in the German Exclusive Economic Zone (EEZ) of the Baltic Sea.

Approval for coastal waters

From the German EEZ, the offshore route continues through coastal waters. For the submarine cable in the coastal waters, a planning approval procedure is required. The competent authority is the Ministry for Economics, Infrastructure, Tourism and Labour of Mecklenburg-Western Pomerania.

In general, the planning approval decision contains a number of ancillary conditions to ensure, among other things, that the construction and operation do not negatively affect the safety of the marine environment or ship and air traffic; many interests are considered and fairly balanced in the scope of the permitting authority’s consideration of the ancillary conditions and other aspects.

Approval for onshore route as well as converter and substation expansion

The point where the submarine cable reaches land is called the landing point. From here on, the electricity generated at sea is transported to the converter by means of an underground cable running along the onshore route.

In the converter, the electricity is converted to 380 kV alternating current. In the neighbouring substation, the electricity is fed into the extra high voltage transmission grid. According to the current planning status, the converter shall be built next to and connected to the new substation to be erected in the scope of the Ostwind 3 project.

The Ministry of Economics, Infrastructure, Tourism and Labour of Mecklenburg-Western Pomerania is competent for the approval of the onshore route. The permitting procedure is a detailed review in which the building permit for the project is issued as well.

The formal public participation is laid down by law. For public agencies, such as the State Agency for Agriculture and Environment of Vorpommern (StaLU Vorpommern), the local nature conservation authority as well as associations and affected private parties, formal participation is prescribed.

As a supporting measure and in advance of formal public participation, 50Hertz organises informal early public participation. Read more about it under ‘Transparency and public participation’. This form of public participation, which is voluntary and based on own experiences, ends where formal public participation by the competent administration begins.

During the preparation of the construction phase as well as during construction work and until commissioning, 50Hertz also informs the public of the activities in the affected region in a transparent manner.

Announcement of platform site for offshore grid connection system (Offshore-Netzanbindungs-System, ONAS) Ostwind 4 (OST-2-4)

Based on the subsoil surveys carried out, 50Hertz announced that the platform of ONAS Ostwind 4 (OST-2-4) will be constructed at the location designated as Site A in the 2023 FEP (Flächenentwicklungsplan, area development plan) (see image below). A change to the site determined in the 2023 FEP is therefore not necessary.

As a result, the final platform site of ONAS Ostwind 4 (OST-2-4) according to the specifications of the applicable 2023 FEP is made public.