The US Department of Energy’s (DOE) Grid Deployment Office (GDO) and the US Department of the Interior’s (DOI) Bureau of Ocean Energy Management published ‘An Action Plan for OSW Transmission Development in the US West Coast Region’, which recommends actions needed to achieve effective coastal and OSW transmission development on the West Coast through 2050.
Throughout 2024, DOE and BOEM led a series of 12 workshops that led to the development of a set of recommendations for addressing OSW transmission challenges along the West Coast. The workshops were complemented by a request for information on related transmission topics. The Action Plan was informed by the West Coast Offshore Wind Transmission Study (WOW-TS) released by DOE national laboratories recently. DOE and BOEM developed over 50 recommendations informed by these inputs. The Action Plan organises these recommendations into five categories that each address a specific transmission development need: planning and operations; partnerships, collaboration and community benefits; Tribal opportunities and support; technology advancement and standardization; and environmental review, siting, and permitting.
Recommendations outlined focus on challenges for coastal and OSW transmission development, and are intended for implementation by federal, state, and local governments, as well as industry. However, the actions would benefit a wider range of entities, including tribes, transmission planners, non-profit organisations, and labour organisations, among others.
In a related development, the Pacific Northwest National Laboratory (PNNL) and National Renewable Energy Laboratory (NREL)—two of the 10 national laboratories managed by DOE—jointly released WOW-TS 2025.The report is a result of a two-year effort modelling the costs and benefits of deploying floating wind along the Pacific coast by 2050. Research results indicate that deploying floating wind offshorethe West Coast could deliver up to 33 GW and help build out needed transmission, but the newly-developed floating offshore wind (OSW) technology and a lack of related infrastructure pose barriers.
The least-cost scenario the researchers identified was adding 13 GW offshore California and 2 GW offshore Oregon by 2035, and increasing that to 25 GW offshore California, 6 GW offshore Oregon, and 2 GW offshore Washington by 2050. This capacity would help the Western US reach the 400 GW of new generation that the region is estimated to need by that year, and assist with the deployment of other generation by bolstering a transmission buildout.
The researchers also studied knowledge gaps, including the optimisation of transmission and generation in the Western Interconnection from 2025 to 2050, geospatial analysis of potential OSW generation and transmission topologies, and the reliability and resilience of each transmission topology.
The study indicates that West Coast OSW transmission could deliver not only OSW energy but valuable contributions to a reliable, cost effective, and clean Western Interconnection. Even when the wind is not generating electricity locally, networked offshore transmission can still transport low-cost energy from onshore like solar, land-based wind, and hydropower.
However, the researchers also found that this deployment would face challenges requiring additional investment to solve. One of the main challenges is that port and grid infrastructure required for this level of OSW deployment does not exist along the West coast presently. The development of one port site could take up to 10 years and cost $1 billion. The report cites a 2023 study that found deploying 55 GW of OSW energy on the West Coast by 2045 would necessitate nine staging and integration sites, that is four or five ports, and 17 operations and maintenance sites, which would require an investment of around $11 billion.
Floating wind is also a newer technology than fixed-bottom wind, especially in the US, where all commercial-scale OSW farms currently in operation or under construction are fixed-bottom. But fixed-bottom OSW is not feasible in the West Coast’s deeper waters, where floating substations and dynamic cables will be critical. But to date, the only floating offshore substation platform in the world was installed as part of a demonstration project in Japan in 2013, connected to three turbines.
There are also challenges for high voltage direct current (HVDC) transmission equipment to be able to withstand the extreme dynamics of being placed on a floating platform. But it is hoped that floating HVDC technologies will be ready by the time commercial-scale floating OSW projects are deployed.
Floating wind also offers some flexibility when it comes to operations and maintenance once a project is completed. Repairs of fixed-bottom turbines must occur at site, but floating turbines can be towed to port, where maintenance can be carried out in a protected harbour.