German energy company innogy SE has reached a Final Investment Decision (FID) on the 342 MW Kaskasi offshore wind farm project in the German North Sea.
In preparation for the construction, contracts for all major components have been signed, innogy said.
Located 35 kilometres north of the island of Heligoland, Kaskasi will feature 38 Siemens Gamesa SG 8.0-167 DD Flex offshore wind turbines. Each turbine will have a capacity of close to 9 MW, a rotor diameter of 167 metres, and a total height of 191 metres.
Wind Turbines and Foundations
The wind turbines, as well as the substation, will be installed on monopile foundations built by Bladt Industries A/S.
Seaway 7 will start the installation of the foundations using a new installation method in the third quarter of 2021 in moderate water depths of 18 to 25 metres. The so called “vibro pile driving” is an efficient alternative to the conventional method of hammering monopiles into the seabed, innogy said. A research project led by innogy has shown that this improved installation method could deliver reduced installation times and noise emissions during construction. Kaskasi will be the first wind farm in the world using the vibro driving technique to install all monopile foundations to target penetration. In preparation for the offshore construction work, extensive seismic analyses have already been carried out, according to the developer.
Offshore Substation and Cabling
Bladt Industries A/S will also construct, deliver, and commission the offshore transformer substation. From the substation, the grid operator will transport the energy via the existing HelWin2 converter platform further to coast. The wind turbines will be connected with the Kaskasi substation via 33 kV aluminium subsea cables with different cross sections. Installation of approximately 50 kilometres of cable will be carried out by Seaway 7. The cables will be manufactured by the Dutch company Twentsche Kabel Fabriek (TKF).
Grid Connection and Start of Operations
It is expected that the wind farm will start operations in the summer of 2022, the final date will be set in coordination with the offshore grid operator TenneT.
Kaskasi offshore wind farm is to be connected to the same grid connection cluster as innogy’s nearby Nordsee Ost wind farm. The HelWin2 converter platform required for connection to the grid has already been operational for several years. Synergies with Nordsee Ost wind farm will be utilised with regard to operations and maintenance work. innogy said. For example the Kaskasi wind farm will be operated from the existing innogy service and operations station on Heligoland.
The contract value for wind turbines and foundations, the offshore transformer substation, and the cabling for the wind farm is in the region of EUR 500 million.
Sven Utermöhlen, Senior Vice President Renewables Operations Offshore at innogy SE, said: “Following our success in the German offshore auction in 2018, we have now taken the next important step in realising Kaskasi offshore wind farm. With Siemens Gamesa, Bladt Industries and Seaway 7 we have brought extremely experienced contractors and suppliers on board for all key components and their installation, which is expected to start next year.”