Borssele Alpha & Beta HVAC offshore substations

The development of the Borssele Alpha and Beta offshore substations is viewed as a piece of Dutch ingenuity. Together, they form part of the first large-scale grid connections realised under the National Energy Agreement for offshore wind farms in the Netherlands. The Borssele Alpha offshore substation connects the Borssele I & II wind farms, located in the south-west section of the Borssele Wind Farm Zone in the Dutch North Sea, to the onshore grid.

Under an EPCI contract awarded to HSM Offshore, Iv acted as subcontractor responsible for the detailed design and engineering of both substations. The scope included procurement support and the integration of the high-voltage components supplied by TenneT TSO B.V., as well as all balance-of-plant materials. 

The designs were developed in line with TenneT’s objectives for high availability and reliability. The grid connection must achieve an availability of 99.964 per cent, allowing a maximum downtime of just3.15 hours per year. Meeting these objectives required precise engineering and careful coordination across all technical disciplines. Both substations were fully certified by DNV GL on three components: the topside, the jacket and the foundation.

Each substation has a transmission capacity of 700 megawatts, together providing 1.4 gigawatts of green electricity to the Dutch grid. Together, they supply sustainable energy to approximately 1.5 million households. They help reduce CO₂ emissions and accelerating the transition to renewable energy sources, bringing the Netherlands closer to its sustainability goals. Borssele Alpha was delivered in the summer of 2019, followed by Borssele Beta in July 2020.