NordOstLink

At least every four years, the Bundestag and the Bundesrat align on the Federal Requirements Plan, in which the measures are laid down that are needed for a stable and efficient power grid in Germany. In July 2022, the NordOstLink was added to the Federal Requirements Plan Act as Project 81. As a result, the project’s necessity for the energy industry and the urgent need for it were made legally effective.

The basis for this stipulation is the Grid Development Plan for Electricity, which is issued regularly and describes the need for development of the German power grid in the years to come. The four German transmission system operators (i.e. including 50Hertz) elaborate these plans together and review them as part of a structured procedure in which the public is involved, after which they are confirmed by the Federal Network Agency.

In the Grid Development Plan for Electricity for 2035 (version of 2021), the project is listed as Project DC31 and justified as follows:

“In Scenario B 2035, an increase in the on- and offshore output of renewable energy in Schleswig-Holstein to approx. 22.5 GW emerges in the year 2035. A total increase in installed renewable capacity across all energy sources from around 11 GW to 22.5 GW is expected by 2035 compared to late 2019; this results in an additional generation surplus in the region. The growth of renewable energy in Schleswig-Holstein leads to critical congestion in the transmission grid, so that additional grid development projects are urgently required in this grid region.

DC31 connects the on- and offshore wind power production on the west coast of Schleswig-Holstein as well as in the North Sea to Mecklenburg-Western Pomerania in order to even out the distribution of power flows across the German transmission grid. The grid expansion project between the Heide survey area (municipalities Hemmingstedt/Lieth/Lohe-Rickelshof/Wöhrden) and the Klein Rogahn survey area (municipalities Klein Rogahn/Stralendorf/Warsow/Holthusen/Schossin) increases the transmission capacity towards the north-east. As such, it helps relieve the stress on the north-south transmission axes, where lines are expected to be subjected to very high loads in the greater Hamburg area, as well as on the alternating current (AC) connections between Schleswig-Holstein and Mecklenburg-Western Pomerania.

The construction of DC31 is an essential grid-technical prerequisite for the transmission of the expected higher output from renewable energy sources, especially from offshore wind turbines, to the eastern north-south transmission axes. This is particularly necessary to evenly distribute the power across the German transmission grid, thus reducing congestion management costs and guaranteeing the security of supply.

For the transmission function of DC31, HVDC technology represents a technically and economically efficient solution. Without the construction of this HVDC connection, far-reaching grid bottlenecks would occur in Schleswig-Holstein and from Schleswig-Holstein to the south; these bottlenecks would then lead to curtailment of the feed-in from renewable energy sources and an increase in congestion management costs.”

The NordOstLink is a connection for extra high voltage direct current (HVDC) transmission. Compared to the conventional meshed alternating current grid, this technology is much better suited for the transmission of large electricity volumes across large distances with few losses, optimal control and in a target-oriented manner.

In order to transport a capacity of two gigawatts, two underground cables are planned that are designed for a voltage of 525 kV. Protective conduits are also laid to avoid the need for additional construction measures, should the demand for transmission capacity increase in the future.

By default, underground cables are laid in open trenches, either inside plastic conduits or directly into the soil. So-called joints connect the different cable sections. The cables are buried deep enough, so that agriculture remains possible. Only woody plants with hard, deep-reaching roots can no longer be planted inside a 15-metre-wide strip above the cable. Alternatively, tunnels can be drilled to pass underneath streets, rivers or highly sensitive areas.

At the starting and end point of the connection, converters transform the alternating current to direct current and vice versa. Near Heide, a so-called hub will be built to connect the NordOstLink to the local alternating current grid. In the middle of the line, a cable section station will be built for technical reasons. Smaller monitoring stations will also be required.

The NordOstLink was embedded in the Federal Requirements Plan Act as Project 81. A direct current connection is planned that will be executed as an underground cable. The legislator also provides the possibility of laying additional protective conduits during construction. The designated end points are the two survey areas near Heide (municipalities Hemmingstedt/Lieth/Lohe-Rickelshof/Wöhrden) and near Schwerin (municipalities Klein Rogahn/Stralendorf/Warsow/Holthusen/Schossin).

The basis for planning and approval is the NABEG. The procedure is handled by the Federal Network Agency located in Bonn and Cottbus. On its website, the authority also provides information about the procedure.

As part of the planning and permitting procedure, the law already provides extensive measures to involve the general public. Nevertheless, 50Hertz will also inform affected administrations, elected officials, associations, nature conservation organisations as well as citizens on the project milestones and ask them for input regarding the plans. Opportunities for dialogue are announced on this website, via local media as well as in the project newsletter. You can subscribe to the latter here with only a few clicks.