Project Colocate: Part 3: East Irish Sea Report

Part 3 of the Project Colocate report presents a comprehensive technical assessment of the feasibility and challenges of colocation between offshore wind (OW) farms and carbon storage (CS) sites in the East Irish Sea (EIS). The study systematically identifies and characterises nine sites where OW and CS interests overlap, evaluating each for spatial and temporal conflict, storage capacity and the presence of legacy wells. Geological risk assessments inform containment and conformance risks for CO₂ storage, focusing particular attention on legacy wells, faults and caprock variability. While many legacy wells meet modern abandonment standards, significant uncertainties remain regarding long-term barrier integrity due to incomplete historical data. The study reviews the compatibility of monitoring, measurement and verification (MMV) technologies with wind farm infrastructure. Conventional towed-streamer seismic surveys routinely used for high-resolution subsurface monitoring are deemed incompatible with wind turbine layouts due to collision risks and operational exclusion zones. Alternative MMV technologies, including ‘spot’ seismic, ocean bottom nodes (OBN), distributed acoustic sensing (DAS) and microgravity are evaluated for technical readiness, cost and operational constraints. While these alternatives can partially address MMV requirements, they generally require repeated vessel access and may not fully substitute for conventional seismic in all geological settings. Colocation scenarios are developed, ranging from complete avoidance to feasible coexistence through compromise such as increased turbine spacing and the creation of access corridors for drilling and monitoring. Colocation may be viable where spatial overlap is limited and legacy well risks are manageable. Early cross-sector collaboration, integrated spatial planning, and regulatory alignment can help to optimise offshore resource use and to minimise operational conflicts. Flexible, site-specific MMV plans and technological innovation will be key to facilitating the colocation of OW and CS projects to help deliver the UK’s Net Zero targets while safeguarding project viability and environmental integrity.