The U.S. is forging ahead with floating OSW development, starting on the coast of California in water deeper than that of any project now being attempted anywhere else globally. Succeeding will require ingenious engineering of complex infrastructure: foundations that support some of the largest structures ever built while also floating in the ocean, transmission systems that bring power to distant sources of demand, and a system of ports and waterfronts to handle the manufacturing and assembly of those structures.

Success will also require coordination among developers and a multitude of federal and state agencies, Native American tribes, fishery groups, various ocean users and other interested parties. Floating foundations eventually will enable more coastal states to add OSW to their power and renewables portfolios. Planning by state and federal agencies is underway to lease the next deep-water areas off the central Atlantic, Oregon, Maine and Hawaii coasts.

California lawmakers and federal regulators have been taking important steps to get planning for commercial-scale floating wind underway. In 2021, California legislators passed Assembly Bill 525, requiring the California Energy Commission to develop a framework for statewide planning and interagency coordination. It also calls for a permitting road map that clearly defines agency interfaces, responsibilities, timing and sequencing, and coordination of reviews under the California Environmental Quality Act and the National Environmental Policy Act.

In February 2022, the California Public Utilities Commission adopted a “preferred system portfolio” that included OSW resources in its integrated resource planning process. Three months later, the California Independent System Operator (CAISO) published its first 20-Year Transmission Outlook to inform transmission planning, focused on meeting California's 100% clean electricity and carbon neutrality goals. The outlook identified a need for significant transmission development to access the OSW energy called for in state resource plans. In December 2022, the federal Bureau of Ocean Energy Management (BOEM) hosted the first auction of federal leases for commercial-scale floating wind projects on the Outer Continental Shelf in the waters of California’s Morro Bay and Humboldt Bay. Five companies ultimately secured acreage:

• California North Floating LLC
• Central California Offshore Wind LLC
• Equinor Wind US LLC
• Invenergy California Offshore LLC
• RWE Offshore Wind Holdings LLC

California will now need to create a clear road map for permitting OSW projects, a strategy to develop ports that can deploy and service OSW, a plan to site, permit and construct transmission, and a procurement policy for the power produced by floating OSW wind.

For OSW on the East Coast, meanwhile, the BOEM plans to hold a commercial lease sale for floating OSW in the Gulf of Maine in 2024. BOEM first published a request for interest for the Gulf of Maine in the Federal Register in August 2022. The following April, the Bureau announced a Call for Information and Nominations, inviting public comment on and developer interest in possible commercial development.

The identification of wind energy areas, a proposed sale notice and a final sale notice all need to be completed before the lease sale can occur. In other words, the next year will be a busy one for OSW in Maine. After two years of extensive public engagement, the state has also released the Maine Offshore Wind Roadmap, which outlines the key actions needed to achieve five major objectives:

1. Pursue OSW supply chain infrastructure and workforce investments to support economic growth and resiliency.
2. Harness abundant renewable energy to reduce long-term costs and reliance on fossil fuels, as well as to fight climate change.
3. Advance Maine-based innovation to compete in the emerging national and global OSW industry.
4. Support Maine’s vital and thriving seafood industries and coastal communities.
5. Protect the Gulf of Maine’s environment, wildlife and fisheries ecosystem.

Before pursuing commercial-scale development, the state of Maine submitted a research lease application for the development of a small-scale, noncommercial floating wind array. The research array would allow regionally specific research on the coexistence of floating wind projects; Maine’s heritage industries, including fisheries; and the marine environment. Study topics could include mooring systems’ impact on the behavior of various fish species and gear selection’s potential impact on fisheries. In January 2023, BOEM found no competitive interest in the research lease.

As specific floating OSW projects come into sharper focus, their permits will address the key differences between fixed and floating technologies and project requirements. Though each project will require empirical considerations based on its location, local environmental conditions and technologies selected for use, plausible effects estimated from analogous activities can be buttressed with results from around the world from demonstration and research floating wind projects and oil and gas facilities that deploy some of the same technologies.

While floating OSW development discussions to date have focused primarily on floating wind turbine generators and their substructures, the heart of a large-scale floating OSW farm will be its substation.

Demonstration-scale floating projects have all followed direct-to-shore topography, feeding power to an onshore substation. The only exception is a 16-MW floating OSW installation approximately 14 miles off the coast of Fukushima, Japan. This demonstration project includes three floating wind turbines and its own floating offshore substation (FOSS).

Future commercial-scale floating OSW projects will almost certainly require offshore substations that can operate in water that is 200 feet (60 meters) deep or greater — depths greater than would be viable for fixed-bottom substation solutions. For example, the state of California, where the ocean floor lies as much as 1,300 feet (400 meters) below the surface, has set a goal of deploying 5 GW in OSW by 2030 and 25 GW by 2045.

To have the stability needed to support safe operation, a FOSS must be able to withstand wind, waves and other environmental conditions. Design must consider how equipment is impacted by movement and acceleration, as well as the structure’s ability to maintain the heel angle.

Due to a floating OSW installation’s distance from shore, location and power requirements, a FOSS must be able to accommodate both high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) solutions. Given significant weight differences between HVAC and HVDC solutions, this creates a literal balancing act for designers that affects both the size and composition of a FOSS.

Developers currently have four main types of floating substructures, also known as floaters, to choose from:

• Spar design. Relying on gravity for stability, a spar is a cylinder that floats vertically in the water. It is often ballasted to make the structure less responsive to wind, waves and currents. A spar design was employed on the world’s first commercial floating wind farm in Scotland.
• Semisubmersible floater. The partly submerged structures rely on buoyancy for stability. Already proven through years of use in offshore oil and gas installations, semisubmersible floaters contain a large deck that is supported by multiple legs that are interconnected underwater by horizontal pontoons. Given their ability to withstand large wave loads, semisubmersible floaters are expected to be the platform of choice for FOSS construction.
• Tension leg platforms. For stability, these floaters rely on a taut mooring system comprising heavy steel rods that are anchored on the seabed. While more stable than a spar or semisubmersible design, a tension leg platform’s anchoring system is more expensive to fabricate and install.
• Square barges. Like boats, these floating platforms have a large surface area that maintains contact with the water, creating a damping pool that helps them maintain stability.

Platform considerations are not the only issue facing floating OSW developers. Delays in technology readiness and other bottlenecks have slowed FOSS implementation, in particular the dynamic export cables and high-voltage equipment.

Should the global floating OSW market progress as planned, demand could outstrip supply and put inflationary pressures on many elements in the supply chain, from the material selected for hull construction to the transition from chain to synthetic lines. The U.S. supply chain’s attention to these issues could result in a win-win scenario for OSW developers and suppliers.

Ports are critical to the development, construction, operation and maintenance of floating OSW projects. Because of the increased on-land activity OSW developments generate, nearby ports may need to undergo expansion and retrofitting to accommodate new OSW projects. In some cases, entirely new ports will be constructed. Three types of ports are required to support OSW projects:

• Marshaling ports are used for floating OSW construction and assembly. These ports require heavy-duty wharves that house heavy-lift cranes and contain large laydown areas. Many existing ports may not have the terminal space and capacity to accommodate the heavy equipment needed for this construction.
  
  When developing the infrastructure for a marshaling port to support new floating OSW installations, it is wise for port authorities to think beyond the initial marshaling operations and consider the infrastructure’s future use. Because of the high cost of port infrastructure, operating leases can stretch for decades. A marshaling port can be transformed into a cargo handling terminal once its original mission is complete. Its infrastructure should be designed to accommodate that future use.
  
  
• Manufacturing ports house facilities where large components of a floating OSW installation can be manufactured before they are transferred to a marshaling port for assembly. Manufacturing ports typically include warehouse facilities where these components can be housed prior to assembly at the waterfront.
  
  
• Operations and maintenance (O&M) ports are smaller ports used to support a floating OSW project throughout its useful life, which can be decades. O&M ports are typically located on waterfront property where small maintenance boats can dock when not providing service at the installation.

In some cases, new specialty ports are already in development. Humboldt Bay in Northern California, for example, will be the site of one such port, with upgrades specifically designed to support floating OSW projects in that region. On the East Coast, deep water ports — including the Port of Albany, Port of Virginia and Port of New Bedford — are making investments to support floating OSW projects. Some OSW developers are also acquiring real estate with the intent to build out the infrastructure for their own ports.

Port authorities that plan to participate in the floating OSW market have multiple design elements to consider for both retrofits and greenfield projects. Chief among them likely will be the upfront investment needed to design, build and operate a port that is as sustainable as practical.

That is because many ports are seizing opportunities to incorporate electrification, battery energy storage and other technologies that support their efforts to decarbonize their operations. The renewable green energy produced by floating OSW further supports this mission.

Ports are unlikely to receive power directly from OSW turbines. Instead, local utilities will likely transport that power onshore via subsea cables to onshore substations before integrating it into their grid.

Ports can still benefit by using renewable energy credits and power purchase agreements to procure a higher percentage of wind energy from their utility. Even in states like California, where up to 59% of power today is provided by renewable and zero-carbon sources, ports can purchase renewable energy credits and enter into power purchase agreements to help them meet their net zero goals.

Bringing down the cost of floating OSW projects will require an industrywide commitment to a green energy future, which is expected to create untold jobs locally and nationally. The payoff could be great. Approximately two-thirds of U.S. wind sources are located over ocean waters that are more than 200 feet deep. In California alone, more than 370,000 acres of deep water have been leased, offering the potential to unlock more than 4.6 GW of OSW energy.

Offshore wind unlocks even more opportunities in the energy transition to decarbonize energy, chemical manufacturing and industrial sectors. Along the Gulf Coast, the ports of Houston and Corpus Christi, among others, have the potential to use OSW energy to support the production of green hydrogen and green ammonia for shipment via vessels and pipelines to users throughout the world.

The floating OSW industry is poised to leave the ground floor. With the support of Wind Shot initiatives, companies with deep experience in energy production, electric grid management and port infrastructure should be poised to help others in the supply chain shape the industry’s future.