Angliviel de La Beaumelle, NilsTehranchi, KamranSimoncini, MatteoShittu, EkundayoAzevedo, Inês M.L.2025-11-122025-11-122025-11-011748-9318PURE: 134818318PURE UUID: faac6418-1150-49d5-9620-ecffd136f9d3Scopus: 105019535973http://hdl.handle.net/10362/190636Publisher Copyright: © 2025 The Author(s). Published by IOP Publishing Ltd.California has ambitious offshore wind goals of 2–5 GW by 2030 and 25 GW by 2045. The coastline deep ocean floor calls for floating offshore wind (FOSW), a new technology whose application has yet to be built to scale. Given the novelty, deep uncertainty, and lack of data regarding FOSW, we fielded an expert elicitation regarding the costs, probability and duration of failure, and likely potential system architectures. We find that there is significant disagreement among experts: cost estimates vary by a factor of at least 3. Probabilities of failure range from 0.01% to 20% for most parts of the system. Experts diverged on likely transmission configurations that are likely to be used with FOSW projects, though most agreed DC technologies will be used in the future. Overall, experts believe California’s 2030 FOSW targets will not be met but could be achieved by 2035, and 2045 targets could be realized with faster buildout of future lease areas.3347118engcostsexpert elicitationfloating offshore windprobability of failuretransmission configurationsRenewable Energy, Sustainability and the EnvironmentGeneral Environmental SciencePublic Health, Environmental and Occupational HealthSDG 3 - Good Health and Well-beingSDG 7 - Affordable and Clean Energyjournal article10.1088/1748-9326/ae0b94https://www.scopus.com/pages/publications/105019535973