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Grid expansion offshore

 

As well as the NEP for onshore, the TSO is also drawing up the O-NEP for the North and Baltic Seas. This determines the requirement for connecting lines for offshore wind farms and sets the time sequence for their construction. The following figures depict all the connection systems of the start and extension grids according to the endorsed O-NEP 2025 and the clusters in the North and Baltic Seas. These so-called clusters are comprised of wind farms in close proximity to one another, and are aggregated and connected to create a joint grid connection. The BNetzA examines the measures suggested in the O-NEP in consultation with the Federal Maritime and Hydrographic Agency (BSH) with regard to their necessity.

 

 

 

 

Depiction of the corroborated connection systems in the North Sea in O-NEP 2030

Data source: [Bundesnetzagentur]

Depiction of the corroborated connection systems in the Baltic Sea in O-NEP 2030

Data source: [Bundesnetzagentur]

 

 

Fourteen different clusters have been identified in the North Sea, and another five in the Baltic Sea. 900 MW 320 KV direct current systems are standard for such joint connections [BSH]. The grid connection systems completed to date now serve Cluster 2 (Alpha Ventus, DolWin1 & 3), Cluster 3 (DolWin2), Cluster 4 (HelWin1 & 2), Cluster 5 (SylWin1), Cluster 6 (BorWin1 & 2) and Cluster 8 (BorWin3) in the North Sea and reaches Cluster 1 (Wikinger) and Cluster 3 (Baltic1 & 2) in the Baltic Sea and is thus available to carry electricity from the wind farm to the grid.

 

As of 2026, calls for tender will be made for areas in the North and Baltic Seas, which will be subject to government investigation beforehand. A transitional model will initially be applied for the period between 20121 and 2025. The expansion resulting from these calls for tender will be divided between 500 MW in the Baltic Sea in 2021, 500 MW in the North and Baltic Seas in 2022, and 700 MW each in the in North and Baltic Seas between 2023 and 2025. The O-NEP 2025 should enable the attainment of these targets. It also regulates a cross-cluster grid connection (as an exception, the permissibility of the connection of a wind farm via another cluster than the cluster in which the wind farm in question is located). [Bundesnetzagentur]

 

The second draft of the O-NEP 2030 was confirmed by the Federal Grid Agency (BNetzA) on 22nd December 2017. It is the fourth O-NEP and no further new versions will be released. The O-NEP 2030 thus forms the basis for the expansion of offshore wind energy from 2026 [Bundesnetzagentur]. It will then be superseded by a zoning plan in accordance with Section 6 of the German Offshore Wind Energy Act (WindSeeG). In this, in agreement with BNetzA, the Federal Maritime and Hydrographic Agency defines the areas in which wind farms are to be built in the future. At the same time, it also defines how and when these areas are to be connected. The zoning plan will thus become the central planning instrument for the use of offshore wind energy. [BNetzA_tenders] ; [Offshore_Network Development Plan

 

The total length of the offshore expansion grid in Scenarios A 2030, B 2030 and C 2030 are around 2,277 km each, whereby 1,527 km are DC grid connection systems in the North Sea and 540 km are AC grid connection systems in the Baltic Sea. Scenario B 2035 presumes a length of 3702 kilometres due to the significantly higher transport requirement in 2035. The overall transmission capacity of the offshore expansion grid is 7.4 GW for target year 2030, whereby 5 GW is for the North Sea and 2.4 GW for the Baltic Sea. A capacity of 11.4 GW has been determined for the target year 2035. The estimated investment volume for the German offshore grid up until 2030 is around € 17 bn, and in Scenario B 2035 around € 24 bn. [UeNB]

 

In September 2016 construction began on the 623 km power line from Germany to Norway. The TSO undersea cable NordLink, with a capacity of 1400 MW, should go into trial operation as of 2019, connecting Norwegian pumped-storage power plants with the German grid, with the aim of facilitating the exchange of renewable energy. Completion is planned for 2020. [TenneT]