This summer, on the 5th of July, the offshore construction on the Hollandse Kust Zuid wind farm officially started. Two years after Vattenfall won the second tender to build the world’s biggest and first subsidy free offshore wind farm, things are now really taking shape. Just before construction started, Ian Bremner returned as project director for Vattenfall’s flagship offshore wind project– after having already worked on HKZ back in 2018. Ian looks back at the first construction campaign, and provides a peek into next year’s activities.
Over the next year and a half, Hollandse Kust Zuid will be built off the Dutch coast. The fossil-free energy generated by the wind farm will benefit not only households, but also small businesses and industrial partners. Ian Bremner briefly served as project director on HKZ in 2018, before moving to Vattenfall’s Danish offshore wind farm Kriegers Flak. When the construction of Danish Kriegers Flak (DKF) was nearly finished, and construction of Hollandse Kust Zuid was set to start, he transferred back to HKZ.
Building a wind farm of this size, with 140 turbines, takes a lot of preparation and a team that really knows what they are doing. Returning to a fully operational team – in COVID times – was demanding for Ian: “Even though I already knew many people from the core team, there were lots of new faces as well. Stepping into the project at this crucial time right before construction started, I had to make sure that we knew exactly what to expect from each other. This is very difficult in the midst of the pandemic, with everybody working remotely. That said, it was made easier by the fact that the team was already operating in a steady state related to Covid restrictions and very used to that virtual environment. Nevertheless, it remains a challenge not being able to have that invaluable face time with the team.
A challenging start with a good recovery
The first construction campaign of Hollandse Kust Zuid saw the installation of the first few dozens of monopiles – the foundations on top of which the turbines are later installed. These foundations and secondary steel components are shipped from foundation manufacturer Sif’s yard on the Maasvlakte by the installation vessel Seaway Strashnov. This ship has a crane that lifts the monopile into the water and lowers the foundations, until it reaches the seabed at a depth of 17-28 metres. Once the foundation is in position on the seabed, a hydraulic impact hammer is used to drive the pile to the final penetration depth.
During this first installation campaign 34 of the total 140 monopiles were installed. “We had a challenging start, due to some unexpected technical difficulties on the foundation installation vessel”, Ian explains. “However, once those were resolved and we were up and running, things went really well, and the pace of installation was meeting our expectations. Unfortunately, further technical difficulties interrupted the momentum and we never quite recovered the earlier performance. The delays pushed the works further and further into adverse weather periods to the point where it was no longer viable to continue. This translated into us falling short of our foundation installation target for 2021.
However, there is flexibility in the start date of the second foundation installation campaign, and that allows the project to recover the installation shortfall from the first campaign. This means that the early challenges do not materially impact the overall schedule. In fact, this first campaign has provided us with lots of opportunity to learn key lessons that we can use to plan and optimize the second campaign, which is a lot more time critical. We are confident that foundation installation performance will improve next year.”
Planning the next campaign
The second campaign should start at the beginning of March, with the installation of the remaining 106 monopiles. Next spring, the first cables and turbines will also be installed. The turbine strings will need to be connected to the offshore substations ready for energization and delivery of first power. The team is using the coming winter period to prepare for this new phase. Ian: “We are performing a great deal of programme analysis and detailed planning to be 100 percent prepared for these first connections to the substations and delivery of power to the grid. We have to manage some very complex interfaces between cable and turbine installation and commissioning. There are so many activities taking place involving so many teams and contractors, and all activities are highly interconnected. We are turning every stone to make sure the planning is perfect and that we have all of our risks in clear view and mitigated.”
On to 2022
“This has been a rollercoaster of a year for me, moving straight from Kriegers Flak, which was nearly finished, to HKZ, which was just at the beginning of the construction process. But delivering the world’s biggest offshore project is something that energizes me every day. The whole team and all of the contractors involved are highly motivated for this project to succeed. Cooperation has been really good at all levels. Of course, we all faced challenges and we have been able to overcome all of them. My primary focus for next year is that we continue to execute the project without incident. Health, Safety and Environmental performance is my top principle, and I will never deviate from it or compromise my position for any short term project gain. I am also energized to travel and have more opportunities to meet my team face to face. This is important to build trust and resilience– a necessity for the high stakes second campaign.”