Risk Assessment Model for Offshore Wind Farm Decommissioning: Analysis of System Uncertainty, Risk Events, and Weather Delays

Abstract. With the ambitious goal of becoming climate neutral by 2050, the EU anticipates a significant expansion of offshore wind energy capacity. An offshore wind farm has an average lifespan of 20–25 years; therefore, the yearly number of turbines in need of decommissioning in the North and Baltic Sea will increase significantly starting in 2030. However, research on this phase is still being carried out and experience is limited. For this reason, this research work enables the development of a comprehensive risk analysis tool that simulates different OWF decommissioning strategies, focusing on critical cost and risk drivers. The methodology is focused on applying quantitative risk analysis to decommissioning project plans. Paired with Monte-Carlo simulations, the proposed method can accurately assess the potential impact of various uncertainties, including systematic uncertainty and discrete challenges. By enhancing the understanding of decommissioning risks, the tool seeks to support smart planning and execution, ultimately contributing to cost reduction and improved viability of offshore wind energy. Findings show that delays derived from process risks can account for over 20 % of project duration. Regarding discrete risk events, availability-related events are found to be among the most significant, stressing the need for early scheduling of ports, vessels, and equipment.