Development and verification of a discrete event simulation tool for high-fidelity modelling of offshore wind and solar farm decommissioning campaigns

Abstract The number of offshore wind turbines to be decommissioned is expected to grow in the next decade but some of the oldest wind farms in the North Sea region are already approaching the end of their service lives. This means that several detailed decommissioning plans will need to be prepared in the coming 2-5 years. So far, only small-scale wind farms consisting of relatively small turbines located in shallow, near-shore, or confined waters have been decommissioned. The limited experience and data available yield high uncertainty in the estimation of costs, duration, and environmental footprint of upcoming offshore wind farm decommissioning campaigns. High-fidelity logistic simulation tools as well as high-level cost models are both needed to support end-of-life decision-making. While several holistic cost models have been proposed, the literature lacks high-fidelity models to support the detailed planning and execution of offshore wind farm decommissioning projects. Given that offshore operations are the greatest source of costs, emissions, and safety risks in decommissioning campaigns, these require special attention when seeking optimization opportunities. In this work, a high-fidelity logistic simulation module for the decommissioning of offshore wind and solar farms has been developed within the discrete event simulation platform UWiSE. The new UWiSE Decommission module enables detailed assessment of alternative decommissioning scenarios taking into account offshore operation complexities like weather and resource dependencies, which are not included or heavily approximated in holistic cost models. The new tool has been verified against publicly available analytical cost model results from recent literature. A short assessment of the impact of weather delays on cost and duration estimates for the considered offshore wind farm decommissioning campaign has also been performed as an example of how UWiSE Decommission may bring value to the planning of offshore decommissioning projects.