As offshore wind energy development grows in the United States, solutions are needed to reduce the underwater noise and substrate vibration generated during fixed-bottom turbine installation to help protect marine life. Monopiles are currently the main turbine foundation type installed globally and use impact hammers to drive these large piles as the primary installation method. This installation method is a major source of noise and vibration during wind farm construction. Opportunities exist to reduce the amount of noise and vibration produced during future offshore wind farm development. The use of alternative foundation types and installation methods, as well as innovative noise abatement technologies, would help reduce the potential detrimental effects on sensitive marine species. In addition to noise reduction, there are multiple other reasons to investigate alternative foundation types, including related to soil condition suitability, domestic content and U.S. jobs, and cost implications.
To explore these opportunities, the U.S. Department of Energy’s Wind Energy Technologies Office, in collaboration with the Bureau of Ocean Energy Management and the National Oceanic and Atmospheric Administration, funded the National Renewable Energy Laboratory and the Pacific Northwest National Laboratory to organize, host, and facilitate a virtual workshop in December 2022. The goal of the workshop was to gather input from the offshore wind energy community on noise reduction strategies for the installation of fixed-bottom offshore wind turbines in U.S. waters across multiple regions, including the Atlantic Coast, Gulf of Mexico, and Great Lakes, to inform recommendations on future research. The joint lab team convened industry representatives, subject matter experts, and regulators to discuss potential pathways to reduce noise and vibration associated with fixed-bottom turbine installation. Workshop participants also discussed the practicality of using alternative foundations and installation methods, the effectiveness of noise abatement technologies, and research and monitoring needs.
In preparation for the workshop, the team invited experts to be part of a steering committee and worked with its members to help focus activities to meet the workshop goals. Additional pre-workshop activities included developing the invitee list and workshop agenda, reviewing existing construction and operation plans for proposed offshore wind projects, distributing a brief questionnaire to industry representatives, and drafting the workshop discussion questions and Mural boards.
In total, 128 workshop participants provided over 600 comments in response to the 17 group discussion questions used over two workshop sessions. In addition to research topic needs, overarching recommendations across themes included future investments to provide data sharing, consistency, and transparency, and opportunities for sharing the best available science, knowledge, and expertise. The joint lab team synthesized the comments and identified four key research and development themes that could help advance the successful implementation of noise and vibration reduction strategies in U.S. waters:
Evaluate the efficacy and costs of existing piling approaches and available noise abatement technologies, as well as the efficacy and costs of alternative foundation types, innovative piling approaches, and novel noise abatement technologies, including assessing technical feasibility at scale of new technologies and collecting data on underwater sound signature characterization.
Develop the U.S. supply chain to increase access to and availability of noise abatement and monitoring technologies as well as increase production capacity for alternative foundations (with consideration of differential CO2 footprints of materials and installation methodologies) and increase use of alternative foundations through investments in ports and installation vessels.
Address the need to develop standards to help provide consistency across models and approaches for alternative foundations, quieting technologies, and monitoring across several topics, including determining design standards, investing in testing construction standards for low-CO2-emitting materials (e.g., concrete options), and improving and developing sound propagation models.
Understand potential impacts on wildlife from piling noise (impact and vibratory), including acoustic sound pressure for marine mammals, waterborne acoustic particle motion for fishes, and substrate-borne vibration for seafloor boundary fishes and invertebrates; understand the potential cumulative effects from installation of alternative foundation types for multiple turbines and wind farm clusters.
This report provides an overview of the workshop goals and scope, reviews the pre-workshop activities, presents brief summaries of participant feedback, and concludes with detailed research themes and recommendations for future investments. The appendices include the results of the pre-workshop industry questionnaire, the full workshop agenda (including workshop discussion questions), and synthesis of relevant information from the construction and operation plans (e.g., foundation types, installation techniques, and noise abatement systems).
Overall, there was a high level of interest and engagement in the workshop. The sessions provided an opportunity for significant exchange of information between workshop participants from across sectors. Participants identified a variety of opportunities for next steps toward the noise reduction of offshore wind turbine installation in U.S. waters, including recommendations for future investments to provide certainty in the use of new technologies associated with alternative foundation types, noise abatement systems, and efficacy monitoring.