Environmental impact assessment framework for offshore wind energy developments based on the marine Good Environmental Status

The expected increase in the offshore wind farm (OWF) developments to meet global decarbonisation targets is raising concerns in the scientific community about the ecological health of the marine environment. The present contribution has conducted an extensive literature review on the environmental effects and changes that the OWF can pose on the Good Environmental Status (GES) described by the European Marine Strategy Framework Directive (2008/56/EC). Consequently, an environmental impact assessment (EIA) checklist has been developed to encompass the construction, operative, and decommissioning phases of the OWF and aimed at enabling the evaluation of whether the OWF developments are conducted compatibly with the maintenance of the GES of the marine environment or not. We have then applied to our case study the developed EIA-GES checklist through a multi-criteria analysis, to evaluate and map the potential level of impact expected from the OWF developments over ca. 45.613,5 Km(2) of a marine area off an Atlantic archipelago. Particularly, biogeographic aspects, oceanographic conditions, and OWF location sites will ultimately determine the overall impact of the OWF development. In our study area, results suggest that the OWF developments would have a minor or null impact on the GES for ca. 78% of the marine waters assessed. Besides, we have discussed our EIA-GES checklist applicability to decide on appropriate possible impact mitigation measures, following a case-by-case approach and identifying key ecological information that could be collected by the OWF developers during the EIA study. These surveys can support environmental authorities by providing with more insights to assess the GES status while identifying information gaps and areas to improve monitoring and data gathering for the GES maintenance. Finally, we discussed performing EIAs based on the historical datasets, and recommend reinforcement of the time series of data with updated surveys within and around OWF sites to confirm the marine environment's state.

Automated summary

This study examines the environmental effects and changes that offshore wind farms (OWFs) can have on the marine environment, and develops an Environmental Impact Assessment (EIA) checklist to evaluate the compatibility of OWF developments with the maintenance of Good Environmental Status (GES). The findings suggest that OWF developments would have minor or no impact on GES for 78% of the assessed marine waters. The study also discusses potential impact mitigation measures and reinforces the importance of data collection and monitoring for maintaining GES.