Today, the RWE wind farm Kaskasi, located around 35 kilometres north of the island of Heligoland, officially commenced regular operation in the presence of Robert Habeck, German Federal Minister for Economic Affairs and Climate Action. With an installed capacity of 342 megawatts (MW), Kaskasi can supply the equivalent of over 400,000 households with green electricity.
The 38 wind turbines of Kaskasi were successively commissioned over four months. Since the end of 2022, all turbines have been feeding green electricity into the grid. After all required tests were successfully completed, the wind farm is now commencing regular operation. The approval procedure for the wind farm started in spring 2019 and construction was greenlighted by the German Federal Maritime and Hydrographic Agency (Bundesamt für Seeschifffahrt und Hydrographie) at the end of 2020. The total offshore construction time was nine months, the investment costs for Kaskasi amounted to around 800 million euros. More than 100 people at RWE alone worked on implementing this large project – hand in hand with the staff from over 70 suppliers.
Offshore wind is a key driver of the energy transition. Offshore wind turbines can produce more electricity during more hours per year than onshore turbines. We have thus increased the expansion targets in the German Offshore Wind Energy Act considerably, to at least 30 gigawatts by 2030. In addition, we have made significant improvements to the legal framework and took action to speed up approval procedures. With the area development plan, we have put the foundation in place for planning the expansion of offshore wind energy in Germany. Kaskasi was the only new offshore wind farm completed off the German coast last year. Its inauguration is to mark a turning point, we now want to drive the expansion of offshore wind energy forward in a targeted and coordinated manner. Dr. Robert Habeck, German Federal Minister for Economic Affairs and Climate Action
First the monopiles used to build the foundation of offshore wind farms are loaded onto transport ships. A total of 38 such behemoths were installed in the Kaskasi wind farm. They weigh 740 metric tons each, equalling the weight of 600 compact cars. © RWE AG
The 38 monopiles made the journey from Eemshaven in the Dutch Province of Groningen, where RWE operates the Eemshaven power station, to their destination some 35 kilometres north of the Island of Heligoland. © RWE AG
Given the three-monopile cargo limitation, it took a total of 13 trips by special ship to transport all 38 monopiles to their final destination. Their maximum length of 64 metres makes them hang over the edge of the ship. © Foto Scheer
Hoisting mechanisms with hydraulic or electric drives known as 'jack-up legs' allow the special ships to 'hover' over the ocean. This enables the ultra-precise operations of the heavy-duty crane to be performed with millimetre accuracy even in very rough waters. The monopiles are rammed into the seabed at depths of 18 to 25 metres. Their upper ends extend out of the water. © DEME Group
Kaskasi is the world's first offshore wind farm to feature 'vibro pile driving', an innovative vibration ramming method supported by the German Ministry of Economic Affairs and Energy. Instead of abating noise using a curtain of air bubbles, this novel technique enables much faster ramming with significantly reduced noise emissions, which is more gentle on the foundation structure. © RWE AG
Once a monopile has been anchored to the seabed, a connecting piece known as a collar is installed. This 170-metric-ton purpose-built collar is moored to the seabed to make the monopile more resilient and stable on challenging topologies – a world premiere. © DEME Group
Once the tailor-made collar has also been installed in the seabed, work on mounting the actual wind turbine can begin. © RWE AG
Our Kaskasi offshore wind farm was the only that was constructed and connected to the grid in Germany last year. Many more must follow over the coming years for Germany to reach its climate targets. As one of the world’s leading companies in offshore wind, RWE can contribute considerably to achieving these goals. Together with our partner we have just selected the preferred turbine supplier for the next offshore wind cluster off the German coast. The cluster will have a total capacity of up to 1.6 gigawatts. And of course, we will also take part in the large German offshore auctions in summer this year. Dr. Markus Krebber, CEO of RWE AG
Of course, the wind turbine towers, rotor blades and nacelles, also referred to as powerhouses, must first be transported to the open sea via heavy-duty freighters. © RWE AG
Once they reach the monopile foundations, the freighter's hoisting mechanism is deployed to enable the precise installation of the towers. © RWE AG
Then the 350-metric-ton nacelles of the Siemens Gamesa SG 8.0-167 DD Flex wind turbines are mounted to the towers. They are roughly as big as a single-family house, the hub height is 107.5 metres. © RWE AG
The final step entails mounting the three rotor blades to the nacelle. Each blade has a length of 81 metres. The wind turbines extend a total of 191 metres from the ground to the tip of the top-most rotor blade when it points directly up into the sky. © RWE AG
The newly developed Recyclable Blades were used for the first time in the construction of the Kaskasi wind farm. Thanks to a novel resin, these blades are the first that can be recycled for new applications at the end of their service life. © RWE AG
Three turbines at the Kaskasi wind farm are equipped with the first rotor blades that can be recycled at the end of their life cycle. What is special about this? Thanks to a new type of resin with a special chemical structure, the materials used for producing the Siemens Gamesa RecyclableBlade can now be separated again for the first time. This process ensures that the properties of the individual materials remain intact so that they can be reused. The recyclable rotor blades are also installed at the Sofia wind farm, which is currently being constructed by RWE off the UK northeast coast.
An offshore wind farm installation would not be complete without the centrepiece, the transformer, known as the offshore substation. The Kaskasi substation is 40 metres high, 25 metres wide and weighs 1,400 metric tons, equalling the weight of 233 fully grown African elephants. © RWE AG
Heavy-duty freighter 'Gulliver' drags the offshore substation to its final destination. Over 60 kilometres of underwater cables have to be laid to connect the substation to the 38 wind turbines. © RWE AG
Work on installing the substation continues deep into the night. The substation is lifted onto the platform bit by bit. © RWE AG
Electricity generated by the offshore wind farm's turbines is harnessed at the substation and converted to 155 Kilovolt (kV) high-voltage current using transformers. This enables virtually lossless power transmission over large distances that can exceed 100 kilometres before reaching the mainland. Kaskasi can produce enough power to supply more than 400,000 homes with green energy. © RWE AG
Dr. Robert Habeck, Dr. Markus Krebber, Marc Becker und Sven Utermöhlen (L-R) at the official opening of the Kaskasi wind farm, already the sixth offshore wind farm from RWE off the German coast. Following the start of construction work in March 2022, Kaskasi is now fully operational and supplying green electricity one year later; the construction time at sea was nine months. A record-breaking speed for which up to 100 RWE employees were deployed (plus external service providers). ©BMWK/bundesfoto/Christina Czybik
Approximately 90 percent of a wind turbine can already be recycled. However, up to now it was not possible to recycle the rotor blades. We are now taking the crucial step to elevate the sustainability of wind turbines to the next level and be able to recycle the entire turbine by 2040 at the latest. Marc Becker, CEO Business Unit Offshore at Siemens Gamesa
After Nordsee Ost (295 MW) and Amrumbank West (302 MW), Kaskasi is the third RWE wind farm that will be operated and maintained from the company’s service station on Heligoland. Around 100 service technicians, engineers and control room staff ensure smooth operation of the three wind farms. And RWE is continuing to drive forward the expansion of offshore wind energy off the German coast. North of the island of Juist, the company is developing the Nordseecluster in collaboration with a Canadian partner. The four sites will feature a total installed capacity of up to 1.6 gigawatts. The two projects (N-3.8 and N-3.7) of the first construction phase with a capacity of 660 MW are currently awaiting approval. The partners are planning to take part in the German government’s offshore wind auctions and to exercise their rights of entry for the remaining two areas (N-3.6 and N-3.5) this year.
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