In the relatively rapid development of offshore renewable energy, the issue of marine biodiversity is often not fully considered. IUCN has undertaken a joint project with the multinational energy corporation E.ON and the Swedish International Development Cooperation Agency (SIDA) to improve the environmental performance of offshore renewable energy projects by developing guidance to support best practice and fully integrate biodiversity considerations.
The Greening Blue Energy project aims to facilitate well-balanced and science-based discussions on the impacts on the marine environment from offshore renewable energy developments.
The guidance provides a synthesis of current knowledge on the potential biodiversity impacts of offshore wind energy on the marine environment. It is based on scientific evidence and experiences from offshore renewable energy development and other relevant sectors. The foundation of the document is a review of more than 1000 reports and documents, at least 400 of which are peer-reviewed articles published in scientific journals, and results are presented in a jargon-free and balanced way. It aims to be user-friendly as well as structured in a way to provide more detail for those that need it and ultimately to encourage improvements in the sustainability of the offshore renewable energy industry. Overall, the guidance promotes the consideration of science-based impact research, suitable for conducting, scoping and evaluating Strategic Environmental Assessments (SEAs) and Environmental Impact Assessments (EIAs), based on international and national standards.
Potential impacts of offshore wind power development on the marine environment include disturbance effects from noise, electromagnetic fields, changed hydrodynamic conditions and water quality, and altered habitat structure on benthic communities, fish, mammals and birds. To date, evidence for negative impacts on the subsurface marine environment are strongest for the construction phase. However, long-term disturbance of local marine ecosystems during the operational phase cannot be excluded, and some bird species may largely avoid the wind farm areas. Various mitigation measures can be applied to reduce the risk to local biodiversity, including difference in timing, location, design of system, and the use of measures to temporarily disperse affected species.
Nevertheless, if offshore wind power development is well planned and coordinated, the local subsurface marine environment could even benefit from wind farms in several ways. Trawling, for both fish and invertebrates, is one of the most severe threats to the marine environment, and is prohibited or limited inside wind farms. Furthermore, the foundations of wind turbines, including the boulders that are often placed around them for scour protection, will function as so-called artificial reefs, locally enhancing biomass for a number of species. It has, moreover, been suggested that surface-oriented offshore energy devices may function as Fish Aggregation Devices (FAD).
All this shows that environmental impacts from offshore renewable energy projects need to be assessed with a comprehensive approach. As the global offshore wind energy industry further expands and continues to mature, companies and governments will benefit from increased knowledge and experience.
Ongoing monitoring will be crucial in identifying how successful previous mitigation strategies have been in avoiding or reducing impacts on the marine environment. Future decisions can integrate new findings and mitigate new threats. By undertaking rigorous impact assessment and systematic environmental management, the industry will continue to learn through the plan, do, check, act approach, and apply continuous improvement to their practices and procedures. Through marine spatial planning, cumulative and synergistic impacts can be better managed, and impacts and opportunities for all sea users taken into consideration.
Planning and development decisions made at this stage of the development of offshore wind energy will be setting a precedent for future developments, both in Europe and beyond, so it is imperative that shortcomings in research and knowledge are addressed as a matter of urgency.