Scour-Protection Strategies for Offshore Wind Farms: A Life Cycle Assessment of Operation and Maintenance Impacts

The operation and maintenance (O and M) phase of offshore wind farms is often simplified in life cycle assessments (LCA), especially with respect to scour-related activities. This study develops a refined O and M–LCA model that explicitly includes scour monitoring, repair, and protection measures, and applies it to a 202 MW offshore wind farm in China. The analysis focuses on the environmental burdens of scour-related O and M activities under predefined engineering scenarios, rather than on the prediction of structural fatigue life or reliability-based intervention timing. Two representative scour-protection strategies were compared: rock dumping (S1) and cement-stabilized soil (S2). The results show that scour protection can substantially increase the environmental burdens of the O and M phase. Relative to the baseline O and M carbon intensity of 4.36 kg CO2-eq/MWh, S1 causes only a slight increase in global warming potential but greatly increases air pollution- and resource-related impacts because of large-scale rock extraction and transport. In contrast, S2 reduces mineral resource scarcity from 2.14 to 0.042 kg Cu-eq/MWh, corresponding to a 98% reduction compared with S1, but raises the global warming potential to 9.94 kg CO2-eq/MWh, mainly because of cement production and offshore treatment. Sensitivity analysis shows that S1 is more affected by hydrodynamic-driven intervention frequency in air pollution-related categories, whereas S2 is more sensitive to seabed conditions and stabilization efficiency in terms of GWP. A site-specific screening framework is proposed by integrating geotechnical and hydrodynamic constraints, regional environmental concerns, and targeted mitigation options. The results provide O and M-stage environmental evidence for the site-specific screening of scour-protection strategies and for improving the environmental performance of offshore wind O and M.