Floating Offshore Wind Turbines Get A Vertical Axis Makeover

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Last Updated on: 27th May 2025, 10:08 am

Everybody knows that wind turbines need to have three blades spinning on a horizontal axis. Still, not everybody is satisfied with that solution. The Swedish startup SeaTwirl, for one, has been exploring the idea of offshore wind turbines that spin like carousels around a vertical axis, and the EU is now ready to bank €15 million on a full scale demonstration of the technology.

Vertical Axis Turbines & The Offshore Wind Solution

The vertical axis field has had a tough time breaking into the onshore wind market. Small scale iterations have been introduced commercially, but so far the technology has resisted megawatt territory.

The news organization Wind Power Engineering summed up the situation back in 2017. Noting that vertical axis technology has the advantage of being more compact than conventional wind turbines, WPE went on to list all the reasons scale-up has been difficult. “The problems of aerodynamic efficiency, self-starting, structural stability, and safe braking remain unsolved,” they observed.

So much for the onshore wind market. The offshore wind market is a different kettle of fish. The US Department of Energy, for example, has been eyeballing vertical axis technology as a means of cutting the cost of floating offshore wind platforms.

“VAWTs [vertical axis wind turbines] offer advantages over traditional offshore wind designs because they have a lower vertical center of gravity and center of pressure; require a smaller, less expensive floating platform; do not need yaw control systems; and have the potential to reduce operations and maintenance costs due to platform-level access to the drivetrain,” explains ARPA-E, an office of the US Department of Energy that provides funding for high risk, high reward early-stage technologies that private sector investors are afraid to touch.

Indeed. Back in 2023 CleanTechnica took note of the expansive design flexibility in the floating offshore turbine field, from a singular, pole-like structure to a tilt-a-whirl configuration (see another floating wind example here).

$7.72 Million For Vertical Axis Offshore Wind Turbines In The USA

Over the past several years, national laboratories under the Energy Department umbrella have been working to apply vertical axis technology to floating offshore wind turbines. Energy Department funding has also supported efforts at other research institutions.

A vertical axis project has been under way at the University of Texas at Dallas since 2019, for example, with a healthy assist from the Energy Department. In addition to an initial grant of $3.3 million, the school received an extension grant of $4.42 million research.

“Their design framework includes aero-elastic tailoring of the rotor to reduce parked and operating loads, coordination of active plasma on-blade flow control with rotor speed control to reduce torque variability, and a lightweight and stable platform design,” ARPA-E notes in a recap of the project.

“Program developments in FOWTs could reduce the cost of wind energy production and provide an entirely new option for the offshore wind industry, as well as access to significant wind resources near major population centers on U.S. coastlines,” ARPA-E emphasizes, with FOWT referring to floating offshore wind turbines.

€15 Million For Vertical Axis Offshore Wind Turbines In Europe

No word yet on whether or not federal support for vertical offshore wind turbines will survive the Trump-Musk chopper. With the extension grant in hand, the University of Texas project is funded through 2027 unless, of course, the sticky fingers of Trump reach out to claw back the award.

Meanwhile, other nations have picked up the vertical axis ball, lured by the prospect of harvesting more clean kilowatts from the sea while cutting the cost of clean power.

Last fall, the EU’s Horizon Europe funding office issued a call for “demonstrations of innovative floating wind concepts.” By the time submissions closed in February, a total of almost 600 entries landed on the agency’s desk.

When the dust settled earlier this month, SeaTwirl emerged with a €15 million commitment from Horizon Europe to fund its “Verti-Go” project, pending finalization of the award.

The SeaTwirl Offshore Wind Solution

SeaTwirl’s vertical axis solution first surfaced on the CleanTechnica radar all the way back in 2011. That was a long time ago, but they have not been letting the grass grow under their feet. By 2022 the company was targeting the commercial market for a 1-megawatt floating offshore turbine.

“SeaTwirl’s unique floating vertical-axis wind turbine has a low center of gravity, a slim substructure, and a generator house accessible at the sea surface enabling small, cost efficient, and locally available vessels to maintain it,” the company explains.

The new infusion of €15 million for the Verti-Go project will enable SeaTwirl to demonstrate its floating wind technology at the 2-megawatt scale, with an assist from an 11-member consortium of industry stakeholders and research institutions.

Don’t get too excited just yet. The award has been won, but EU regulations require a grant preparation step that will take about three months. Assuming successful completion of grant prep, the project timeline will officially begin in August, when the design phase kicks off.

If all goes according to plan, the design phase will conclude by the end of next year. Construction will not begin until halfway through 2028, and the green light for operation is not anticipated until the end of 2029.

Meanwhile, Here In The USA

All else being equal, floating offshore wind turbines — vertical axis or not — would find a welcome home in the US. Practically the entire Pacific coast is too deep for conventional fixed-platform turbines. The same goes for the Gulf of Maine on the Atlantic coast.

Wind speeds in the Gulf of Mexico are not particularly optimal for wind development, but the Interior Department has designated offshore wind lease sites there. “The Gulf has significant generation and industrial potential that could provide a reliable, clean source of energy to customers in Florida, Alabama, Mississippi, Louisiana, and Texas,” explained the National Renewable Energy Laboratory in an offshore wind transmission report published last year.

The outlook for new floating wind farms in the US is gloomy, to put it lightly, now that the Trump-Musk alliance has taken a chainsaw to federal research programs. Trump’s abrupt suspension of the entire offshore lease program didn’t help, either.

However, it’s a big world out there. Floating wind startups that benefited from millions of dollars in Energy Department funding in previous years can float their turbine platforms away to other countries that are still eager to decarbonize the global economy.

There goes all that taxpayer-funded R&D, down the drain. So much for cutting out waste and fraud. If you have any thoughts about that, drop a note in the comment thread. Better yet, find your representatives in Congress and drop a note to them.

Image (cropped): The Swedish startup SeaTwirl is on track to scale up its vertical axis floating offshore wind turbine for a demonstration funded by the EU agency Horizon Europe (courtesy of SeaTwirl).