The COBRA cable is an initiative of the Dutch high-voltage grid operator TenneT and the Danish electricity and gas grid operator Energinet. Construction started in 2016 and was completed earlier this year. The interconnector cable runs between Eemshaven (the Netherlands) via Germany and Endrup (Denmark). Two onshore converter stations, one in the Netherlands and one in Denmark, convert alternating current into direct current. This is necessary to transport the electricity without major losses. The converters also convert direct current back into alternating current; electricity grids operate on the basis of alternating current.
Siemens is the main contractor for design and technical equipment of the converter stations in Denmark and in the Netherlands and for the construction of the converter station in Eemshaven. The cables were manufactured and installed by Prysmian.
IGBT converter tower inside the COBRAcable converter station in Eemshaven (photo: Siemens)
Advantages of the COBRA cable
The Netherlands can import more sustainable electricity via this interconnector cable, mainly wind energy from Denmark. Ensuring security of supply is of great importance to Denmark. The cable makes Dutch capacity available on a structural basis for the Danish electricity grid and vice versa. Furthermore, the cable connection has been designed in such a way that it will be possible to connect an offshore wind farm at a later stage. In this way, the cable contributes to realizing a sustainable international energy landscape, an important goal of the European Union.
The converter station of COBRAcable in Eemshaven (photo: TenneT)
Cross-section of the COBRAcable system (TenneT-Energinet)
Trading electricity via COBRAcable
The capacity will be made available to the long-term, day-ahead and intraday electricity market.
- Long-term: At the first auction after one month of stable operation TenneT and Energinet will periodically offer long-term transmission rights (LTRs) for trade between the Netherlands and Denmark. Two variants of LTRs will be offered, a yearly product spanning a full calendar year, and a monthly product covering a calendar month. Both will be auctioned via the auction platform of JAO S.A.
- For day-ahead and intraday the capacity of COBRAcable will be made available to the market via the day-ahead market coupling and intraday market coupling process. These processes are operated by the power exchanges which are designated as NEMO ('Nominated Electricity Market Operator'). In the Netherlands, two NEMOs are active: EPEX SPOT and Nord Pool.