The Ostwind 2 project team closes the year with another important milestone: The second of a total of three sea cable systems was successfully laid in the seabed. This brings the connection of the Baltic Eagle offshore wind farm another step closer. The third and final cable is to be installed in 2022. The laying of the first cable system was already completed in September. This establishes the connection to the Arcadis Ost 1 wind farm.
“We kept our word,” explains Dr Henrich Quick, Head of Offshore at 50Hertz. “In 2016, we promised to install two cable systems within five years. We have achieved this ambitious goal in part through good and trusting cooperation with partners and suppliers.”
Prior to the cable installation work, the structure of the seabed and the water depths are surveyed and then analysed. Depending on the nature of the seabed and the depth of the water, different installation techniques are used. In addition, offshore sea cable are highly complex devices; special insulating layers are wrapped tightly around the three cable core phases made from copper and mechanical shields made from metal result in a high weight. A metre of submarine cable weighs approximately 120 kilograms. This makes the transport from the production facility to the offshore installation site logistically demanding. A cable system of 90 kilometres can therefore not be laid in one continuous segment, but is divided into several cable sections. The individual sections are between 13 and 37 kilometres long and are connected with sub-sea cable joints. Laying a cable section takes approximately two to four weeks, depending on a number of factors, such as weather and sea-state conditions.
“This shows that we put a lot of thought into the proper planning of logistics and technical implementation in advance so that we can keep to our schedules,” Dr Quick emphasises in conclusion.
Ostwind 2 is the project to connect the Baltic Sea wind farms Arcadis Ost 1 and Baltic Eagle to the German extra-high voltage grid. To transfer the power from the two wind farms, 50Hertz plans to build three submarine cable systems that will transmit a total of 750 megawatts (MW) of power.