About 15 miles off the Norwegian coast, five turbines are spinning in water roughly 260 to 300 meters deep. They are bolted to nothing on the seafloor. Instead, each 8.6-megawatt machine sits atop a steel spar buoy held in place by mooring lines and anchors, riding the swells like a ship while generating electricity that flows through a subsea cable to the Snorre and Gullfaks oil platforms and, from there, into Norway’s grid. The project is Hywind Tampen, developed by Equinor, and as of late 2023 all 11 of its turbines were operational, making it the world’s largest floating offshore wind farm at 88 megawatts.
That milestone matters far beyond the North Sea. It proves that wind turbines can produce reliable power in ocean depths where no rigid foundation could ever be driven into the seabed. And according to the federal government’s own resource data, the wind blowing over those kinds of depths represents the majority of offshore wind energy available to the United States.
The scale of what fixed foundations cannot reach
The National Renewable Energy Laboratory maintains the U.S. government’s primary offshore wind resource assessment. That assessment identifies approximately 2.8 terawatts of technical wind potential in waters where floating platforms are the only viable option, spread across the Pacific Coast, the Gulf of Maine, Hawaii, and parts of the Gulf of Mexico. A separate 1.5 terawatts sits in shallower zones suitable for fixed-bottom foundations, the kind already being built off the Mid-Atlantic coast.
To put those numbers in perspective, the entire installed U.S. electricity generation fleet, every coal plant, gas turbine, nuclear reactor, solar panel, and wind farm combined, totals roughly 1.3 terawatts of nameplate capacity. The deep-water wind resource alone is more than double that.
NREL’s own explainer on floating technology states plainly that the 2.8 terawatts of potential “blows over waters too deep for fixed-bottom foundations,” a point the lab underscored in a 2023 analysis on what it will take to unlock U.S. floating wind. The International Energy Agency’s offshore geospatial mapping tool, built with Imperial College London, confirms the pattern globally: once water depth exceeds roughly 60 meters, fixed-bottom monopiles and jacket foundations hit their practical engineering and economic limits. Beyond that line, floating platforms are the only game.
How a floating turbine stays upright in open ocean
Fixed-bottom offshore turbines work like telephone poles sunk into the ground. A steel monopile is hammered into the seabed, and the tower rises from there. That approach works in depths up to about 50 or 60 meters. Beyond that, the structural steel required becomes prohibitively heavy and expensive, and installation vessels cannot handle the loads.
Floating turbines take a fundamentally different approach. The turbine and tower are mounted on a buoyant hull, typically one of three designs: a spar buoy (a long, ballasted cylinder that extends deep below the waterline for stability), a semi-submersible platform (a wide, shallow structure with multiple columns), or a tension-leg platform (held taut by vertical tendons anchored to the seabed). All three use mooring lines and anchors rather than rigid foundations, allowing them to operate in hundreds or even thousands of meters of water.
Hywind Tampen uses the spar-buoy design that Equinor first tested with a single 2.3-megawatt prototype off Norway in 2009 and then scaled to a five-turbine, 30-megawatt pilot array off Scotland’s coast in 2017. That Scottish project, Hywind Scotland, has operated for more than seven years and recorded capacity factors above 50 percent in some periods, competitive with the best fixed-bottom farms in the North Sea.
Where the U.S. stands on floating wind
The Bureau of Ocean Energy Management has already held lease sales specifically targeting deep-water zones that require floating technology. In December 2022, BOEM auctioned five lease areas off the California coast near Morro Bay and Humboldt County, where water depths range from about 500 to over 1,000 meters. Those leases generated $757 million in winning bids. In 2024, BOEM finalized a lease sale for areas in the Gulf of Maine, another region where the continental shelf drops off quickly and fixed foundations are not feasible.
Oregon’s offshore wind planning is similarly oriented toward floating technology, with BOEM advancing two call areas off the southern coast. Hawaii, surrounded by deep Pacific waters with strong trade winds, has long been identified as a prime candidate but faces unique grid-integration challenges given its isolated island grids.
None of these U.S. projects are close to generating power yet. Environmental reviews, engineering design, supply-chain buildout, and port upgrades all stand between a lease and a spinning turbine. The first commercial-scale U.S. floating wind farms are not expected to deliver electricity before the late 2020s at the earliest, according to developer timelines filed with BOEM.
The cost question floating wind must answer
Fixed-bottom offshore wind took roughly a decade of deployment in European waters before costs fell dramatically. In the early 2010s, projects were contracting at prices above $200 per megawatt-hour. By 2019, some North Sea auctions cleared below $50. That cost curve was driven by larger turbines, purpose-built installation vessels, and a maturing supply chain.
Floating wind is earlier on that curve. Hywind Scotland’s electricity was initially supported by U.K. subsidies well above market rates. Hywind Tampen’s economics are somewhat different because it displaces gas-turbine power on oil platforms, where the alternative fuel cost is high and Norway’s carbon tax adds further incentive. Neither project reflects what commercial-scale floating wind will cost in a competitive power market.
NREL’s 2023 cost projections estimate that floating offshore wind could reach levelized costs between $60 and $100 per megawatt-hour by the early 2030s if deployment scales and supply chains mature. That range would make it competitive with new natural gas generation in some markets but still above the cheapest onshore wind and solar. The trajectory depends heavily on whether governments provide the long-term offtake contracts and port investments that let manufacturers commit to serial production of floating hulls, rather than building each one as a custom project.
What deep-water wind could change for coastal grids
For states like California, Oregon, and Maine, floating wind is not an optional upgrade to a fixed-bottom strategy. It is the strategy. Their offshore wind zones sit almost entirely over deep water. Without floating technology, those states have no path to large-scale offshore generation.
The resource also has characteristics that complement other renewables. Offshore wind tends to blow strongest in late afternoon and evening hours along the Pacific Coast, coinciding with the period when solar output drops and electricity demand peaks. Winter wind speeds are generally higher than summer, filling a seasonal gap that solar cannot cover. If deployed at scale, deep-water wind could help displace the natural gas peaker plants that California currently relies on during those high-demand windows.
Grid integration, however, remains a serious bottleneck. Delivering large volumes of power from remote offshore zones requires new subsea export cables, onshore substations, and sometimes transmission upgrades extending hundreds of miles inland. Those investments take years to plan and permit, and their timelines rarely align neatly with wind farm construction schedules. If transmission lags behind generation, developers face curtailment, stranded capacity, and weakened project economics.
There is also a significant gap between NREL’s 2.8-terawatt technical potential and the amount of energy that can realistically be developed. Shipping lanes, fishing grounds, military exclusion zones, visual-impact setbacks, whale migration corridors, and wake-spacing requirements all reduce the usable area. The developable share will be a fraction of the technical total, though even a small fraction of 2.8 terawatts represents a transformative amount of generation capacity.
From prototype to proof point
Hywind Tampen’s 11 turbines are not going to power a country. At 88 megawatts, the farm is a rounding error against the scale of the resource it is designed to prove accessible. But the project’s significance is not in its output. It is in the operational data it generates: how the spar buoys perform in North Sea storms, how mooring systems age, how capacity factors hold up across seasons, and what maintenance costs look like when technicians must reach turbines by boat or helicopter in rough water.
That data feeds directly into the investment decisions now being made for the California, Maine, and Oregon lease areas. Every quarter of reliable operation from Hywind Tampen and its predecessors lowers the risk premium that lenders attach to floating wind projects. Every engineering problem solved in Norwegian waters is one fewer unknown for developers planning installations off Humboldt County or Casco Bay.
The resource has been mapped, measured, and published by federal and international agencies. The engineering has moved from simulation to open ocean. What happens next depends on whether the economics close fast enough to meet the timelines that coastal states have set for decarbonizing their grids. The wind, at least, is not the constraint.
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*This article was researched with the help of AI, with human editors creating the final content.
