The US West Coast offshore wind (OSW) sector received a policy roadmap in the form of a transmission action plan, just days before the new administration paused new leasing activity in federal waters. The US Department of Energy (DOE) and the Bureau of Ocean Energy Management (BOEM) released the “Action Plan for Offshore Wind Transmission Development in the US West Coast Region” on January 16, 2025. However, on January 20, 2025, the new administration ordered the temporary withdrawal of all areas on the outer continental shelf from OSW leasing pending a review of the leasing and permitting practices for wind projects. While this creates uncertainty in the short- to medium-term, particularly on the West Coast where OSW is yet to take off due to deep waters off the Pacific Coast requiring floating OSW technology, the region could potentially host substantial floating OSW capacity in the long term.

The DOE-BOEM Action Plan addresses the offshore wind transmission (OWT) challenges on the West Coast and recommends ways to connect the first generation of OSW projects to the Western grid while supporting transmission over the next several decades. It is informed by the DOE and BOEM workshops and a 2024 request for information on related transmission topics, the DOE’s Wind Energy Technologies Office (WETO), “West Coast Offshore Wind Transmission Literature Review and Gaps Analysis” of February 2023 and the West Coast Offshore Wind Transmission Study (WOW-TS) released by the DOE’s national laboratories on January 15, 2025. The latter, conducted by the Pacific Northwest National Laboratory (PNNL) and the National Renewable Energy Laboratory (NREL), was funded by the DOE’s Grid Deployment Office (GDO) and WETO. The two-year WOW-TS assesses infrastructure needs, transmission topologies, and integration pathways for up to 33 GW of OSW capacity by 2050 into the Western Interconnection. It proposes a phased OWT approach, beginning with radial transmission by 2035, eventually evolving into an interregional network by 2050. The study finds that coordinated planning could unlock up to USD25 billion in net economic benefits, improve grid reliability and facilitate regional energy goals.

This article presents the findings of the WOW-TS study and Action Plan, highlighting key conclusions, challenges and policy recommendations for floating OWT on the US West Coast.

Current state of OSW on the West Coast

According to the DOE, about two-thirds of the US’ OSW potential exists in deep waters, more suitable for floating OSW projects than fixed-bottom wind turbines. The West Coast has a technical potential of 83.5 GW of floating OSW off California, Oregon and Washington. The previous US administration set an ambitious target of achieving 15 GW by 2035, while cutting project costs by over 70 per cent to USD45 per MWh.

To help achieve these targets, in December 2022, BOEM leased five areas in federal waters off California for USD757.1 million, marking the region’s entry into large-scale OSW development. The two leases in Humboldt (north California) and three leases near Morro Bay (central California) hold the potential for 3 GW and 5 GW of floating OSW projects respectively. However, the planned 3.1 GW Oregon lease auction (Brookings and Coos Bay) was postponed in September 2024. In November 2024, BOEM released the draft Programmatic Environmental Impact Statement for the California leases, evaluating strategies to limit environmental disruptions and conflicts while advancing OSW. However, BOEM has halted any potential new leases and postponed or cancelled meetings on existing leases due to the orders from the new administration.

States have set their own targets. California aims for 2-5 GW of OSW capacity by 2030 and 25 GW by 2045, supported by the California Energy Commission’s Offshore Wind Strategic Plan, which integrates OSW into the state’s energy mix, ensuring grid reliability and supporting carbon neutrality by 2045. Notably, the California Public Utilities Commission approval (August 2024) for the procurement of 7.6 GW floating OSW capacity requires additional leasing activity. Oregon’s Offshore Wind Energy Roadmap explores up to 3 GW by 2030, balancing economic growth, environmental protection and grid integration. Meanwhile, Washington focuses on OSW supply chain opportunities, monitoring California and Oregon to leverage regional synergies.

The California Independent System Operator (CAISO) plays a crucial role in facilitating OSW integration into the state grid. CAISO’s latest approved 2023-24 Transmission Plan includes 400 miles (643.74 km) of new infrastructure on California’s North Coast at an investment of USD4.59 billion to support 1.6 GW of OSW, which can be expanded for future OSW in line with its 20-year Transmission Outlook. This plan addresses grid congestion issues and enhances grid reliability, enabling efficient power flow from offshore wind farms (OWFs) to demand centres. CAISO is also exploring advanced grid management technologies, including dynamic line ratings and flexible AC transmission systems, to optimise grid operations and accommodate the variable nature of OSW power. Additionally, it coordinates with neighbouring balancing authorities and utilities to develop an integrated regional transmission network, supporting the West Coast’s renewable energy transition.

Key highlights of WOW-TS

The study optimised generation and transmission capacity, spanning the Western Interconnection over the years 2025-50, taking into consideration the state energy legislation, national electricity emissions reductions of 90 per cent by 2035 and 100 per cent by 2045, restrictive siting of future land-based renewable energy, and the projected cost of all technologies. The resulting least-cost systems included 15 GW OSW in 2035 (13 GW in California and 2 GW in Oregon) and 33 GW in 2050 (25 GW in California, 6 GW in Oregon and 2 GW in Washington). The total generation expansions of approximately 200 GW by 2035 and 400 GW by 2050 were also incorporated.

Further, geospatial analysis across the region guided the creation of five OSW generation and transmission topologies to deliver this energy to onshore points of interconnection (POIs). This optimisation was similar to the method used for the 2024 Atlantic OSW Transmission Study for the East Coast, although the POIs were decided pre-optimisation in this work. OSW development during 2035-50 has been defined across five topology sets, leading to six discrete pathways. In 2035, the concentrated topology will interconnect through five POIs and the distributed topology will utilise nine POIs. In 2050, the study defines radial, intraregional and interregional topologies with the prior POIs, generation footprints and power injections but incorporates distinct strategies for transmission coordination. It also assessed the reliability and resilience of each transmission topology. Further, community perspectives were considered by evaluating the potential influence of OSW topologies on ecosystem services.

The topology sets were inspired by the goal of analysing the differences in 2035 between more distributed injections (2035 Distributed) and more concentrated ones (with fewer POIs, 2035 Concentrated).  In 2050, the analysis and differences between the topologies were focused on designing a topology that is entirely radial (2050 Radial), compared to one with onshore multi-terminal high voltage direct current (MT-HVDC or MTDC) interlinks within regions (2050 Intraregional), and compared to another with offshore MTDC interlinks (2050 Interregional)

Transmission topologies and grid integration

Radial topology: Radial transmission involves direct, point-to-point connections between individual OWFs and onshore substations. This can be achieved in a radial concentrated topology where multiple wind turbines in a single OWF are connected to a single offshore substation, which then transmits power to a designated onshore substation or POI. Alternatively, in a radial distributed topology, multiple OWFs are each connected to individual offshore substations, which then transmit power to multiple POIs. Radial transmission is an effective short-term solution but becomes inefficient as OSW deployment expands, necessitating a transition to more integrated transmission systems.

Intraregional network: This topology enhances reliability by connecting multiple OWFs to a shared transmission network before linking to the onshore grid. This approach offers greater flexibility in managing power flow and reduces the risk of isolated transmission failures. However, it involves higher upfront costs due to the need for additional offshore substations and inter-array cables.

The 2050 Intraregional topology provides connections within the combined Bonneville Power Administration (BPA) and the PacifiCorp West (PACW) region, and the CAISO region with high voltage alternating current (HVAC) and HVDC transmission equipment. Approximately 16 GW are routed through HVDC in a single north coast corridor, with HVDC being connected through an MTDC network on land. Unlike traditional HVDC systems that operate point-to-point, MTDC allows for multidirectional power flows between multiple connection points.

Interregional network: It represents the most advanced and efficient OWT system, which involves linking multiple OWFs across different states and grid regions using an HVDC backbone. This topology provides maximum redundancy and grid stability, ensuring that power generated offshore can be flexibly distributed across multiple demand centres. However, such networks require significant investment, long-term planning, and resolution of regulatory hurdles, including interstate transmission approvals and cost allocation.

The 2050 Interregional topology provides additional connectivity between BPA, PACW and CAISO. The same POIs are used as in the intraregional topology and all the generation and transmission defined in both 2035 topology sets are included to allow for the consideration of multiple deployment pathways. The HVDC lines are connected through an offshore MTDC backbone and lines to shore are routed in a distributed manner to the target POIs.

Key findings

After considering co-uses and bathymetry, the study found that over 30 GW of OSW could be hosted in the available sea space off California and southern Oregon within 1,300 metre depths. The study coordinated system reliability analyses with system operators on the West Coast to ensure grid resilience across all topology sets. The key study findings include:

  • Infrastructure requirements: Upgrades for all topology sets ranged from 3,693 km to 9,709 km of conductors, 13-43 transformers, 15-28 series capacitors, and 3-25 substations. Costs were lowest for the 2035 Distributed Topology (8 billion) and highest for the 2050 Interregional Topology (USD26.7 billion). Key improvements include the lines connecting the Humboldt substation to the 500 kV Fern Road substation, the substations at Gates and Midway, the 500 kV Los Banos–Midway line, which includes a loop into the Gates substation, and the transmission upgrades in the Fern Road and Lugo areas. The 2050 Interregional topology required greater enhancements, particularly in the Moreno Valley, Bakersfield, Santa Rosa and Oceanside areas. Redispatch through MTDC networks shows minimal changes to the reinforcements in the 2050 topology sets.
  • Cost efficiency: In 2035, distributed interconnections reduced system reinforcements by 25 per cent, saving approximately USD3.6 billion compared to concentrated interconnections.
  • System stability and resilience: Dynamic contingency analysis showed mostly stable system responses, though some instability was observed in certain BPA, CAISO and Western Electricity Coordinating Council (WECC) contingencies. Future studies are needed to address these challenges through remedial action schemes or additional transmission infrastructure.
  • Grid strength and integration: The study identified moderate to strong grid conditions for most POIs in the 2035 Concentrated topology, while weak grid conditions were noted at the Fern Road POI during high OSW dispatch scenarios. Accounting for the contribution of existing inverter-based resources toward short-circuit current improved grid strength at key POIs.
  • Wildfire resilience: Synthetic dynamic contingency modelling based on historical wildfire showedall topology sets had stable frequency responses, highlighting resilience to wildfire-induced disruptions.
  • Economic analysis: Coordinated OSW transmission holds strong economic value. Of the six pathways evaluated, significant benefits-cost advantages were indicated for pathways leading to the 2050 Interregional and Intraregional topologies over the 2050 Radial topology. The best net benefit pathway observed was the 2035 Distributed topology to 2050 Interregional topology, which delivered USD25 billion in net present value over the 2050 Radial topology. In the near term, both 2035 topologies showed similar system-wide benefits through alternate cost structures.
  • Technology: Commercial OSW floating is both a challenge and an opportunity as the industry is currently in the nascent development stages. The main technology hurdles relate to export cables, floating substations, floating HVDC equipment, and operations and maintenance.

Challenges in OWT development

Infrastructure and technology: Deploying floating OSW technology presents engineering challenges, particularly for dynamic HVDC cables and floating substations, which are still in the early stages of commercialisation. Developing port infrastructure to support floating wind is another major issue. Additionally, large-scale battery energy storage integration or alternative solutions, such as green hydrogen production, would be required to mitigate the impact of OSW’s intermittent nature on grid stability.

Regulatory: OSW transmission regulations are complex and have been impacted by shifting federal policies. While the previous administration’s Floating Offshore Wind Shot initiative reinvigorated OSW development by committing USD950 million in funding, the long-term stability of federal support remains a key question with the new administration’s approach to wind energy expansion.

Workforce development: The availability of a skilled workforce, including engineers, offshore technicians and high-voltage transmission specialists to support the OSW industry remains critical for its large-scale expansion.

Key highlights of Action Plan

The Action Plan presents a strategic framework for OSW integration into the Western energy grid while addressing infrastructure limitations, regulatory barriers and economic feasibility. Unlike fixed-bottom OSW, which has progressed significantly on the East Coast, floating OSW necessitates an entirely different approach due to deep-water conditions, lack of existing infrastructure and complex interregional transmission needs.

The plan prioritises grid resilience, cost optimisation and regulatory coordination for a scalable, interconnected OSW system. A phased approach is recommended, with initial radial configurations by 2035 to support early OSW projects. By 2050, the system is expected to transition into a networked interregional transmission system, enhancing energy reliability, reducing costs and enabling a flexible power flow between states.

Recommendations and future outlook

The Action Plan presents recommendations across five key areas to foster a coordinated, efficient and resilient OWT:

Planning and operations: The plan emphasises a phased, flexible approach for OWT development, ensuring cost-effectiveness and grid reliability in line with WOW-TS findings. This includes 20-year transmission plans and near-term interconnection investments to maximise economic benefits while minimising risks of underutilised assets. For instance, CAISO’s plan for the North Coast project exemplifies this approach, which involves building HVDC infrastructure from Humboldt to Collinsville, but initially operating it as a 500 kV AC line until higher capacity and HVDC converter station costs are justified. The plan recommends the utilisation of advanced modelling tools to forecast energy demands and optimise transmission capacity, besides incorporating OSW in existing transmission planning efforts as well as long-term resource adequacy and long-term regional transmission plans. Further, transparent cost allocation mechanisms and funding strategies must be established. Discussions on system-wide cost allocation for future interregional transmission facilities must be initiated to ensure the equitable distribution of grid costs across regions and maximise ratepayer benefits. Transmission planners and operators must consider alternative financing methods, including leveraging public funding sources.

Partnerships, collaboration and community benefits: A key focus of the action plan is fostering partnerships and collaborative frameworks involving federal agencies, state governments, industry and local communities to build a new transmission system, ensuring regulatory coordination, community benefits and equitable economic growth. It recommends the establishment of a multi-state collaboration to coordinate OWT planning, permitting processes, regulatory approvals and supply chains across California, Oregon and Washington. The implementation of community benefit agreements could ensure coastal communities directly benefit from OWT investments, job creation and economic development opportunities. A strategic focus on building an integrated transmission system to support large-scale OSW deployment must include upgrading existing infrastructure, developing new transmission corridors, and leveraging advanced grid management technologies. There must be a greater focus on educating and training a skilled and extensive energy and grid workforce.

Tribal opportunities and support: West Coast Tribal Nations have expressed concerns about the OSW’s impacts on sacred sites, fisheries and cultural resources. The Action Plan calls for early engagement with tribal communities, incorporating indigenous perspectives into planning and environmental impact assessments. It also recommends the development of tribal-led environmental studies, allowing for direct tribal participation in assessing OSW impacts and mitigation strategies. Additionally, it calls for tribal consultation frameworks that facilitate economic participation and investment opportunities, ensuring OSW development is both culturally sensitive and economically beneficial.

Technology advancement and standardisation: To support the scale-up of OSW, the plan calls for the development and demonstration of floating offshore substations, HVDC breaker technologies and dynamic and HVDC cables that can withstand harsh marine conditions while ensuring reliable power transmission from floating OSW turbines. Standardisation and interoperability of HVDC equipment will cut integration costs and accelerate the commercialisation of floating OSW technology. Collaboration between national labs, industry and universities is essential to accelerate innovation and reduce costs.

Environmental review, siting and permitting: The plan calls for an accelerated, coordinated approach to environmental review and transmission siting. One strategy is to designate preferred transmission corridors and streamline approvals for OWT lines, while ensuring compliance with environmental regulations. Investment in geospatial mapping technologies is also recommended to identify optimal transmission routes that minimise environmental and social impacts. Balancing environmental protection with infrastructure expansion will be crucial for ensuring the sustainability of OSW projects. Better coordination among permitting agencies will reduce delays and enhance OSW’s attractiveness to investors.

The way forward

The Action Plan represents a comprehensive roadmap for integrating floating OSW into the US power grid. If implemented successfully, the recommendations could unlock significant economic benefits and facilitate a just energy transition. However, achieving these goals will require sustained collaboration among and support from federal and state agencies, private developers and local communities. With greater clarity on the new administration’s approach to OSW development as well as technological advancements in floating OWT systems, the West Coast could harness its huge potential for floating OSW energy in the medium- to long-term.