Teamwork and a no-rush culture: Building Germany’s largest offshore wind project
For nearly a decade, German utility EnBW has been transitioning to make renewables a mainstay in its energy mix. Its first offshore project - Baltic 1 - was also the country’s first offshore commercial wind power plant. In 2015, EnBW Baltic 2 started operations and by January 2020, both EnBW Hohe See and EnBW Albatros, built as one 610-MW offshore project, were connected to the grid. While Siemens Gamesa has been a trusted partner for all these projects, for Hohe See and Albatros, the company went beyond its usual scope of wind turbine delivery. Here’s an account of what it took to build this mega project on the high seas.
Siemens Gamesa and its partners started from scratch. The company would supply and commission 87 SWT-7.0-154 turbines,then the latest products in its portfolio; SCADA systems i.e. the ‘nerve center’ connecting the turbines, the offshore substation for Albatros, and other systems for monitoring and control, while also managing integration of interfaces. Construction of the foundations on which the turbines would be placed, offshore substations to collect and transmit the power generated, project certification, and servicing were part of the extended scope.
“With 30+ years in offshore wind, and more than 16GW installed globally offshore, we have proven experience along the entire value chain. With its EPCI scope - Engineering, Procurement, Installation, and Commissioning – Hohe See/Albatros is among the largest projects we’ve executed, taking on commercial and interface risks. Mitigating these risks for the mutual benefit of EnBW, Enbridge, ourselves, and society-at-large, has been central to our work,” explains Zaitz.
A no-rush culture emphasizing safety
Safety is my choice. We value Siemens Gamesa's commitment to safety as a partner on this project.
He went on to say “During the construction of Hohe See and , more than 600 people worked and lived on the construction site. More than 80 vessels were deployed. Throughout this time, the team followed strict safety practices resulting in no significant safety incidents”.
DEME Offshore was responsible for the design, fabrication, installation, and commissioning of all 88 large monopile foundations. Some weighed over 1,000 tons and are more than 70 meters long. Additionally, DEME Offshore was responsible for the corresponding transition pieces including scour protection, along with the Offshore Transformer Module topside installation.
“From the first day, the various teams of Siemens Gamesa and DEME Offshore engaged in a solution-oriented joint collaboration, which resulted in the successful development of a smart foundation design. In this process, turbine loads, site specific soil and sea conditions, fabrication constraints as well and transport and installation constraints were carefully considered whilst a strict time-schedule for design, review and certification was successfully maintained. Towards the end of the installation phase, DEME Offshore deployed its state-of-the-art installation vessels INNOVATION and SEA INSTALLER to ensure the originally planned start-date for both projects could be met. We are very proud of this joint achievement, which can be added to the many other successful joint achievements our companies have made,” notes Bas Nekeman, Business Unit Director, DEME Offshore.
The work on the offshore substation (OSS) ran in parallel. A vital part of offshore wind power plants, substations, transform voltage and transmit the energy as collected from the turbines to the grid. The OSS for Hohe See was constructed in Hoboken, Belgium, and installed by June 2018. Work on the Offshore Transformer Module (OTM) for Albatros started at Zwijndrecht, the Netherlands, in early 2018. “The OTM Albatros contributes to the success of Germany’s energy transition. Contamination of the marine ecosystem with mineral oil is impossible thanks to the use of ester as insulation material for the transformer and a battery system for emergency power instead of a diesel generator,” Simon Isensee, Senior Project Manager Offshore Platform, Siemens Energy Management.
InOctober 2018, the first nacelle was ready to be shipped from Siemens Gamesa’s Cuxhaven factory. Nacelles weigh as much as 400 tons, and the factory’s proximity to the German North Sea reduces transportation costs and time. “This project was special – the first nacelles from our factory built for Germany’s largest offshore wind power plant. We were honored to contribute. Our young but experienced team did our utmost to deliver the nacelles at the high quality level our customers expect, on time in accordance with the project schedule,” states Anton Bak, Plant Manager – Cuxhaven, Siemens Gamesa.
InMarch 2019, the Albatros substation was installed and by August, the installation of the turbines at Hohe See was completed. In September, the last of the 16 wind turbines were installed at Albatros. Since January 2020, all 87 turbines from both plants feed electricity into the grid. Siemens Gamesa continues to service and maintain the turbines. A specially commissioned ship acts as a floating service station. After two weeks at sea, the technicians are flown back to land by helicopter.