Multi-criteria decision-making for offshore wind farm decommissioning: Lessons from the oil and gas sector

The current decision-making process for offshore wind farm (OWF) decommissioning projects in the UK continental shelf (UKCS) is primarily based on the economic aspects. It aims specifically to secure an appropriate form of financial guarantee from developers to ensure they can finance the decommissioning and that assets will not be abandoned on the seabed at the end of their operational lifetime. However, OWF decommissioning projects have environmental, technical, safety, and societal impacts, hence necessitating the development of a multi-criteria decision-making approach. This study proposes a multi-criteria decision-making (MCDM) framework, adapted from the comparative assessment (CA) process used in the oil and gas (O&G) decommissioning sector, in which the economic, environmental, and safety criteria are considered to evaluate each decommissioning option. To assess these, bottom-up impact assessment formulations are developed in which detailed site-specific and operational parameters are considered. The Gunfleet Sands OWF in the North Sea is assessed as an exemplar decommissioning case study. The results produced by the proposed MCDM framework are visualised using an immersive marine simulator, which serves as an effective stakeholder engagement platform for OWF decommissioning projects. The study offers valuable insights into the sustainability, safety, and financial implications of various OWF decommissioning scenarios.