Offshore wind farm decommissioning and its impacts on marine biodiversity and social acceptance

While major wind farm development projects are put in motion to support the green transition, the first offshore wind farms (OWF) are reaching the decommissioning phase. OWF decommissioning potentially includes a broad range of options from “remove all” to “leave in place” with different impacts on biodiversity. Throughout the lifetime of an offshore wind farm, the ecosystem around the wind farm structures often transforms into a more species-abundant and diverse ecosystem as the wind farm foundations act as artificial reefs. The impacts of removing these ecosystems are largely unknown, and at the same time, objective methods for assessing such impacts are needed to support decision-making around OWF decommissioning. Furthermore, understanding the social perception of different decommissioning options and their impacts on marine biodiversity will be essential to ensuring transparency and acceptance from society. Based on a literature review, we identified impact pathways for impacts on marine biodiversity from decommissioning activities, which will form a basis for the development of a quantitative model (life cycle impact assessment model) for biodiversity assessment. Furthermore, we investigate the social perception around decommissioning in Danish civil society and by national authorities, environmental NGOs, and marine specialists.