TY - RPRT
TI - Social Acceptance of a Reduced-Footprint Synthetic Mooring System for Floating Offshore Wind Turbines in the Gulf of Maine
AU - Green, R
AU - MacDonald, S
AU - Fuchs, R
AU - Hall, M
AB - For generations, the Gulf of Maine has been an area of active marine uses, including commercial and recreational fishing across a multitude of species and gear types, representing businesses from the three coastal states in the region, Maine, Massachusetts, and New Hampshire. In 2022, the Bureau of Ocean Energy Management began a process to facilitate the development of offshore wind energy in the Gulf of Maine, which will require the use of floating offshore wind turbine technology, given the region’s significant water depths. A floating offshore wind farm comprises an array of floating offshore wind turbines, each anchored to the ocean floor with a mooring system (typically three lines) featuring chain and/or rope mooring lines.Engineers are looking to reduce the size of floating offshore wind mooring footprints to minimize conflict with other ocean users. To this end, the University of Maine received funding from the U.S. Department of Energy to design, demonstrate, and validate a novel, reducedfootprint, synthetic mooring system for floating offshore wind turbines that reduces impacts to fisheries and the levelized cost of energy. The study presented in this report was conducted by the National Renewable Energy Laboratory and sought to independently gather fishing industry and other marine user feedback on the potential interactions of their activities with a conventional, chain-based, catenary mooring system as compared to a rope-chain hybrid mooring system that has a reduced footprint on the ocean floor. These “catenary” chain and “semitaut” hybrid mooring systems were designed by the University of Maine and then adjusted and evaluated independently by the National Renewable Energy Laboratory.NREL held 10 discussions with marine users including commercial fisheries, fishing organizations, and state and federal regulatory agencies. Feedback on fishing gear interactions broadly represented both the fixed and mobile gear types and fishing practices in the region, including those associated with lobster traps, groundfish and squid trawling, scallop dredging, and tuna harpooning. A primary safety consideration identified by the discussion participants was the potential to snag fishing gear either on the floating offshore wind turbine mooring line resting on the seabed or the portion hanging in the water column. In addition to the horizontal footprint of the mooring system, multiple other characteristics of the mooring lines were of interest to participants including the curvature of the lines, the touchdown point of the lines, natural burial of the lines on the seabed, anchoring characteristics, and considerations for marking.Study results indicate a modest increase in accessibility and acceptance for a single wind turbine using the rope-chain hybrid mooring system design. Across all rankings, the hybrid design was most often identified as being somewhat more accessible and acceptable than the conventional design based on the smaller footprint and the potential to leave more space open for fishing activities. The rankings were significantly caveated with respondents largely not able to separate the footprint of a single turbine’s mooring lines from array considerations related to turbine spacing. Generally, study participants felt that if the hybrid design with the smaller footprint maintained an adequate corridor between wind turbines for fishing activities, then the reduced horizontal footprint presented advantages. However, not all respondents felt this way, with some concerned with the length of mooring line in the water column (in addition to the amount of line on the seabed) and others having concerns about the use of synthetic rope in the hybrid design (e.g., durability).This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications. Respondents noted several additional considerations related to mooring configurations and interactions with fishing and other ocean-use activities. For example, they conveyed siting as a top priority and asked that regulators and developers avoid siting projects in areas that are considered of high value to fisheries and that have sensitive benthic (i.e., seafloor) habitat. Numerous respondents felt that mooring footprint and wind turbine spacing considerations could not be separated. They conveyed that as mooring footprints decrease, regulators and developers should avoid reducing spacing between turbines so as not to further restrict the area available for fishing activities. In response to spacing considerations, we note that a smaller mooring footprint would typically not be expected to affect wind turbine spacing, which is mainly driven by energy yield considerations based on wind resource and wake effects, as well as safety considerations for the fishing industry and other ocean users, and additional regulatory inputs. All respondents identified marking as a priority for understanding the location of mooring lines underwater, which could include marking anchors with lit buoys, additions to nautical charts, and/or marking mooring lines with a transponder to avoid gear interactions. Commercial fishing participants conveyed that they would avoid fishing within proximity to the mooring lines and likely focus their efforts elsewhere. Some suggested that as knowledge of potential interactions with floating offshore wind turbines and mooring lines increase, they might consider fishing in greater proximity particularly if they are in a financially lucrative area. Based on feedback, future research could consider potential interactions with arrays of floating offshore wind turbines and the floating balance of system (including both mooring lines and power cables), as well as expand on the types of media (e.g., video, virtual reality) available to support marine users to better understand floating offshore wind turbine technology and minimize potential interactions with their activities.
CY - Colorado, United States
DA - 2023/05//
PY - 2023
SP - 48
PB - National Renewable Energy Laboratory (NREL)
SN - NREL/TP-5000-85503
UR - https://www.nrel.gov/docs/fy23osti/85503.pdf
LA - English
KW - Wind Energy
KW - Floating Offshore Wind
KW - Human Dimensions
KW - Social & Economic Data
ER -