Expansion of offshore wind power: Yellow colossus for the energy transition

Offshore facilities for the North Sea are being built in Cádiz, Spain. This has been more difficult economically since the beginning of the war, but one thing is politically clear: the expansion should go faster.

Green sea, deep blue sky – and a yellow steel colossus: 70 meters long, 30 meters high and weighing 11,000 tons. For three years, a German-Spanish team has been building the “DolWin kappa” wind power transformer platform, which is intended for the German North Sea, in the shipyard in Cádiz in the south of the country.

The heart isn’t beating yet

Halls and chambers are distributed over eight floors, packed with transformers, insulators, pipes, cable harnesses and rods. The project manager of the network operator Tennet, Daniel Birkenstock, shows a corridor with control cabinets on both sides: “This is the brain of the system. These are control cabinets with IT equipment that control all components. 500,000 meters of cable have been laid on the platform for this purpose .”

But what is particularly important is the one cable 90 kilometers long that, in a year and a half, is to bring electricity from the Godewind 3 wind farm off Norderney to the coast with low losses – to the Emden-Ost substation. The “DolWin kappa” platform converts alternating current from the wind turbines with a voltage of 155 kilovolts (kV) into direct current with 320 kV.

This happens in meter-high converter towers, which Tennet project managers describe as the “heart of the platform”. As soon as this heart beats, the corresponding rooms of the platform are strictly secured: “They are designed for air insulation – that means you cannot enter this room during ongoing operation. You would trigger an electrical flashover with 360 kV. You would die. ”

War in Ukraine causes prices to rise

The converter technology comes from Nuremberg from Siemens Energy, the Spanish company Dragados builds and installs the platform – this teamwork had to be established first, says Dragados Vice President Cristina Sanz: “We cooperate with our partner Siemens in a team of Spaniards and Germans with different specialist areas . We had to adjust the way we work. It was more difficult at first, until we understood what they needed from us and what we could contribute, and after that initial period of adjustment we work very well together.”

But the pandemic and the consequences of the Ukraine war are making it difficult to work together in southern Spain. building material is scarce; Steel, copper and energy have become more expensive. The industry has to rethink its profit margins, says the responsible Siemens Energy board member Tim Holt: “In the end, it will also affect consumers. That’s a reality that we all have to accept.”

Grid expansion crucial

The general economic conditions have become more difficult as a result of the Ukraine war; According to Siemens Energy board member Holt and Tennet managing director Tim Meyerjürgens, he even promoted wind power politically. The traffic light coalition has set ambitious goals: In the next eight years, they want to increase wind power at sea by more than three times.

These specifications are all the more ambitious because not a single offshore wind turbine was connected to the grid last year. Tennet Managing Director Meyerjürgens is hoping for a stronger political tailwind: “Just setting goals is not enough, we actually have to speed up the approval process. The federal government’s Easter package focuses heavily on the expansion of renewable energies. In the second package in the summer, we have to focus on expanding the network take.” After all, grid expansion is ultimately the backbone of the energy transition, says Meyerjürgens: “If we don’t speed up grid expansion, we won’t achieve the goals.”

Prepared for the “wave of the century”

The construction of the “DolWin kappa” substation platform is a step towards this goal. In three months she is to be shipped from Càdiz to the North Sea. Off Norderney, a special ship will first anchor the substructure in the seabed and then place the platform on it.

The substructure is still standing in the shipyard in Cádiz. The steel structure is 40 meters high – and for good reason, says Tennet project manager Birkenstock: “We have the so-called hundred-year wave as a design basis, which is a wave that has a probability of once in a hundred years, and it has to platform without any problems, so that in the end we are 22 meters above the water level with the platform.” The upper edge of the platform will even be a good 50 meters above the water, twice as high as the Brandenburg Gate.

The plant will go into operation in a year and a half. Together with two other wind farms, it will supply electricity for around one million households from 2026.