Two years after Vattenfall won the second tender to build Hollandse Kust Zuid, the world’s biggest and first subsidy free offshore wind farm, things are taking shape. Although foundation construction is well under way, the company reported it is falling short of its installation target for 2021.
This summer, on the 5th of July, the offshore construction on the 1.5 GW Hollandse Kust Zuid wind farm with 140 Siemens Gamesa SG 11.0-200 DD wind turbines officially started. Over the next year and a half, Hollandse Kust Zuid, owned by Vattenfall and BASF) will be built off the Dutch coast. 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. In a latest press release by Vattenfall, Bremner looks back at the first construction campaign, and provides a peek into next year’s activities.
During this first installation campaign 34 of the total 140 monopiles were installed. The foundations and secondary steel components are shipped from Sif’s yard on the Maasvlakte and installed on site by the installation vessel Seaway Strashnov.
“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.”
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.” Source: Vattenfall