'Floating wind's Tesla moment' | Supersize tilting turbine targets energy mainstream by 2030

Floating vertical axis wind turbines (VAWTs) – designed with blades that are set at angles to the tower rather than upright as on the vast majority of industrial models turning today – have long been heralded by many in the offshore engineering community as key to harnessing the vast, high-velocity wind resource streaming over the world’s deep waters in the years ahead.

Norwegian technology developer World Wide Wind (WWW) thinks it has solved the commercial impasse with one word: contra-rotation. The Oslo-based start-up says its eye-catching design, which features two omnidirectional rotors spaced apart on a tower-spar structure all anchored with a novel turret-shaped mooring system to the seafloor, could be a game-changer for the sector, deflecting away “destructive levels of torque and vibration” – and slashing floating wind’s levellised cost of energy (LCOE) to €50/MWh ($49.85) from current levels over 2.5-times higher.

WWW’s contra-rotating design, which it reckons could be scaled up to a giant 40MW nameplate model, is engineered to neutralise torque on the tower – a well-recognised show-stopper for VAWTs – and because both the concept’s stator and rotors turn at once, it has made it possible to use a “simpler, lighter, and less expensive generator” while “getting two turbine’s output merged into one”.

“Representing a design without a legacy, a more integrated design can also be made from the start, specifically for floating, to further improve costs,” Knutsen adds, pointing to the collaborative environment among partners including Norwegian R&D outfits Sintef and North Wind, Uppsala University and classification body DNV that has informed the project so far.

CEO Trond Lutdal states: “The battle [of industrialising wind] is offshore, in 60 metres [of water] and deeper, so you need floating structures. [Our concept] moves away from the complexity of three-bladed technology which was designed for land or at best fixed [offshore] foundations – I mean, no one was thinking floating when they designed the first windmill-type turbines – and resolves many of the issues around scaling, which is key to cutting cost.”

The slender-profiled CRVT, which tilts in the water with the wind, “part vertical and horizontal axis”, he notes, also has “much lower” wake effect [the turbulence created as wind moves through a rotor-star] than three-bladers, meaning a developer could “halve the distance between turbines on a wind farm, which is super-important for efficiency in capturing wind in a project site area”.

Lutdal adds: “People talk about the profitability of floating wind and it soon becoming competitive [with bottom-fixed offshore]… but there is a step-change needed in the technology to really answer the ‘how’.”

A very big part of the ‘how’ in fact has nothing directly to do with the turbine concept, but instead the birthplace of WWW’s design – and the Nordic nation’s maritime industrial heritage.

“Norway has a fantastic point of departure [into the floating wind sector] given our maritime and oil & gas history, our technologically advanced industrial culture, a strong tradition of public-private partnership – and, of course, our great offshore wind resources,” says Lutdal.

“Looking today at floating wind from a historical vantage point, we could say [in Norway], “We’ve done it before, from the 1970s in offshore oil & gas, but for many, many years before than in maritime. And I think people in our country are beginning to see the dignity of the potential of floating wind. That’s the macro,” says Lutdal.

“From the market standpoint, we have the offshore technology development knowledge, the people and the skillsets to solve complex industrial problems. And the political climate is changing [in favour of offshore wind].

“I can’t speak for [Norway’s] government but I believe we are finally ready to make serious effort to [accelerate the sector’s development].”

Next-gen innovation in sustainability

Next-generation innovation runs in the veins of the WWW concept, with lower-cost materials for the tower and foundation – aluminium over steel – and recycled fiberglass over new-use fiberglass and carbon for the blades – “factored in” to coming designs.

“There are on first inspection five or six areas where we can see real opportunities for greater sustainability in the CRVT than with horizontal axis turbines,” says Lutdal.

Moving forward WWW aims to accelerate development of the technology with “rapid prototyping” to get up to a 3MW model by 2026 of the CRVT and then make the leap to the giant 40MW design by 2029, “spinning off designs for a range of offshore applications along the way”, including deepwater charging stations, renewables-powered aquaculture and green hydrogen generation.

“The time is right for this technology to be tested out,” says Lutdal. “Five years ago, I don’t think it would have flown. But with the energy crisis in Europe, the energy transition globally, the absence – to our minds – of a solution for floating that will really make a fundamental difference to its economics, we are at the pivot point.”