EirGrid Completes Survey Campaign for 900 MW Irish Offshore Wind Link

The completion of marine and coastal surveys under the 2026 campaign for a 900 MW offshore wind development represents a critical preparatory milestone for transmission system operator EirGrid. Offshore transmission infrastructure demands rigorous baseline surveys before export cable corridors, landfall points, and onshore interconnection substations can be finalised. By establishing seafloor stability, coastal geology, and potential subsea obstacles, the campaign delivers the geotechnical certainty required to design subsea high-voltage transmission lines and determine where they enter the onshore grid.

For substation engineers and grid planners, the cable landfall and corridor definition dictates the layout, reactive power needs, and protection schemes of the onshore collector station. High-voltage export cables spanning long marine distances introduce significant capacitive charging currents, which require substantial shunt reactor compensation at the onshore landing substation. Finalising the route and landing zone ensures that transmission engineers can accurately dimension compensation reactors, gas-insulated switchgear, and step-up transformers without facing late modifications to civil and electrical packages.

Moreover, TSO-led survey campaigns reflect a coordinated delivery model designed to resolve routing bottlenecks early. Establishing precise landfall and coastal ground conditions allows project developers and network operators to evaluate soil thermal resistivity, trenching constraints, and sedimentary shifts that could impair cable ampacity. For transmission operators managing onshore networks, acquiring this data early avoids redesigns of onshore grid connection bays and minimises the risk of construction delays during switchgear and transformer installation.

What this means for asset owners in the UK and Ireland: For transmission and generation asset owners in Ireland, the conclusion of export corridor surveys clarifies onshore substation landing requirements and opens the procurement window for long-lead high-voltage switchgear and shunt compensation plant ahead of physical grid connection works.