Kontek

Pylons would have taken longer to approve. That is why Kontek’s 119 km of onshore route is buried: the Kontek article says underground cable was chosen so the link could be finished on schedule, since permission for overhead lines can take a long time. Only about 52 km of the roughly 170 km route is submarine; 50Hertz gives the overall length as about 170 km.

The link runs from the Bjæverskov converter station on Zealand, crosses the island of Falster to the coast near Gedser, passes under the Baltic Sea and comes ashore in Mecklenburg to reach the converter station at Bentwisch, near Rostock. It was commissioned in 1995, though the List of HVDC projects gives 1996.

The need for direct current here is not the distance. Eastern Denmark, including Zealand, belongs to the Nordic synchronous area, while Germany is part of the Continental European one, and two grids that are not synchronised cannot be tied together with an ordinary AC line. The HVDC explainer covers this in more detail.

The cable itself is an older design: paper-insulated and oil-filled, with two copper conductors of 800 mm² permanently joined in parallel. On land it is divided into sections of about 8 km, separated by oil-tight joints for monitoring. ABB and NKT Cables supplied the equipment, and the link is operated by Energinet in Denmark and 50Hertz in Germany. At 400 kV and 600 MW, it is the larger of the two links between Zealand and Germany, and the only one of them built purely for trade.

Bentwisch has since gained a second job. The back-to-back converter of the Kriegers Flak Combined Grid Solution stands at the same site, so two different kinds of link between Denmark and Germany now end near Rostock.