Kent was contracted by Vattenfall to design the secondary and tertiary structures for the 140 offshore wind turbine generator (WTG) foundations for the Hollandse Kust Zuid 1-4 wind farms.

Kent developed novel solutions for the challenging TP-less concept and were flexible to adapt the design late in the project based on client preferences.

Despite relatively late changes due to the project's novelty and complexity, Kent were still able to reduce the weight of the external working platform by around 40% through a design optimisation phase for the beam grillage. This was completed using MODOT, our in-house optimisation software coupled with the SESAM global model, which allowed significantly more design iterations to be considered.

The project has been running for over three years and will culminate in 140 individual 11MW WTGs with a combined power output of 1.5GW. The wind farm is already generating power. However, the complete wind farm is scheduled for operation in 2023.

Highlights from the project included:

Successful installation of the TP-less WTG foundations, including offshore installation of all secondary structures.

Design and installation challenges have been overcome through effective collaboration between Kent and Vattenfall, together with the installation and fabrication contractors.

Technology advances: Connection design details were developed specifically for the requirements of the TP-less installations and the high wave run-up pressures. This included a BLS uplift restraint, which Kent identify as the BLS ‘5th support’.