The Kiel Canal (“Nord-Ostsee-Kanal” in German), a 95km long canal in the German federal state of Schleswig-Holstein, saves shipping industry an average of 460km by preventing it from going round the Jutland peninsula. In fact, the Kiel Canal (and not the Panama or Suez Canal, as one might think) is the busiest artificial waterway in the world. This makes it particularly challenging to cross the Kiel Canal with an overhead line, and the TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), has to master this challenge for the construction of the so-called Middle Axis (“Mittelachse”).
A 220kV overhead line has been in operation between Hamburg and Denmark since 1971. TenneT is replacing this old line with a new 380kV line capable of transmitting seven times as much green electricity. This is necessary given that Schleswig-Holstein produces many times the amount of wind energy that can be consumed locally. New and more efficient lines must therefore be built to transport renewable energies from the land between the seas to the German consumption centres. The Middle Axis is thus not TenneT’s only local extension project and is supplemented by coastal lines (East-Coast-Line and West-Coast-Line respectively). On the Danish side of the border, the Danish TSCNET shareholder Energinet will continue the Middle Axis from Frøslev to the Kassø substation, thereby increasing the electricity trading capacity between Denmark and Germany.
Now TenneT’s work on the Middle Axis has progressed so far that the crossing of the Kiel Canal is on the agenda. Since more than a hundred ships pass through the canal every day, a closure is not acceptable. Because of this, detailed coordination, in particular with the responsible shipping authority, and the use of helicopters were required. On 2 May, TenneT began to fly the auxiliary ropes over the canal. These ropes are aids with which the actual conductor ropes can be installed later. The two pylons on each canal bank, which are connected by the helicopter flight, have a height of about 80m and are thus considerably higher than the other pylons of the Middle Axis.