The wind industry’s Olympian ambitions reached new heights – and rotor diameter – today with OEM Vestas unveiling its 15MW offshore turbine design, the V236, a titan flying 115.5-metre-blades that promises to “move boundaries” in the sector and will be able to singlehandedly power 20,000 homes with every turn.

The machine, which noses the Dane out ahead of rivals Siemens Gamesa, now progressing a 14MW model announced last May, and GE, whose Haliade-X concept has been upscaled to the same nameplate from 12MW at launch, firmly plants Vestas’ flag in the offshore market, underlining its strategic decision earlier this year to buy-out its partner in the MHI Vestas offshore joint venture, Mitsubishi Heavy, and go it alone.

The V236-15.0MW, which will capture energy from unprecedented 43,000m²swept-area, will be able to generate around 80 GWh/year – 65% higher annual energy production (AEP) than the V174-9.5MW. A 900MW wind farm of the new machines, by Vestas’ calculations, would see AEP up to 5% higher based on 34 fewer turbines.

The supersize design benefits from much of the work done in Vestas developing the modular EnVentus platform – so far only used onshore – that has been dovetailed with the in-field experience taken from the process of evolving the MHI Vestas offshore design up its gears in recent years from 7MW up to reach the 10MW, for the V174.

This is not just to be the biggest. That’s not the target at all. This is about building a sustainable business around technology

Blade design for the new giant is based on scale-up of the OEM’s ‘structural shell’ concept for this biggest in-production turbine model – “a known technology we can take forward”, says Vestas chief technology officer Anders Nielsen, speaking to Recharge after the launch.

So too is the medium-speed two-stage geared drivetrain and permanent magnet generator, but here for the the first time wired into twin-set converter electronics with liquid-immersed transformers that will stream the energy to the grid while an “all new” mainframe design channels stupendous torque loads down the tower.

Vestas has also finessed the other side of the loading equation, adjusting the blade tip-speed “slightly” to reduce torque and “get up to this 15MW rating” on the back of a capacity factor of above 60%, Nielsen notes, a full 10% higher than the industry’s average offshore.

“It’s all a challenge. It is a big beast of a structure. But it will give us the capacity factor we are after. It is a good size,” he says. “The EnVentus platform has given us the opportunity to both carry over [existing technology to new larger models] and carry forward and make next steps on the technology.

“Technology principles of scaling-up that were in the thinking on the EnVentus platform have been brought very much into this new design,” he says, referring to the original ambition when EnVentus was launched that this would be concept first for onshore but suitable to offshore designs of eventually even larger nameplates than 15%.

“The technology risk is incremental,” says Nielsen. “The machine we have launched is much bigger than the one before but we are scaling the technology re-using parts used onshore [for EnVentus units] – meaning that we have the chance to quality-assure the components already before we scale up for offshore.”

There have also been far-ranging lessons that have fed into the V236 from the experiences gleaned during the MHI JV, which built up a strong international portfolio of orders and saw steady installation rates of its machines off Europe.

“There have of course been many important learnings. And it has been a case of taking many of the field experiences from the V164/174 and bringing that in [to the new design],” says Nielsen.

“We should not at all underestimate the value of what we have done already – things are moving so fast we are these days talking about ‘legacy’ products that haven’t even seen first installation yet. We are learning fast. But we can’t make a PowerPoint presentation about a fantasy monster [of a turbine]. That does nothing for anyone.

“This is a technology market. What we want is to develop a product about which we have good knowledge in how to build it, how to bring it to market.”

A contract with an as-yet-undisclosed testing centre has been inked, according to Nielsen, for the blades and nacelle componentry, with the prototype to be up and turning next year, and first units ready for market by 2024.

With the global offshore wind power industry expanding at a rate of knots – and forecasts from energy sector bodies and analysts alike pointing to a several-trillion-dollar market by mid-century as the fleet explodes from 35GW to 1.4TW, Nielsen urges a measured view be taken as to how fast the development of offshore wind turbine technology should be driven.

“There are definitely opportunities in [upsizing turbines toward 20MW],” he says. “We know how to use [modular designs] to continue this [scale-up]. But the cost efficiencies are going to flatten out given that the installation cost becomes ever bigger [with larger turbines] – at point you have to ask if you gain that much,” he says.

“So for [Vestas] and the whole industry I would say we need to get to that point where you actually use the technology launched for some years [before moving to the next generation model] and that way bring all our suppliers with us and the industry grows.

“There is a technology race out there and we know how to run it. It is not just to be the biggest. That’s not the target for us at all. This is about building a sustainable business around technology,” concludes Nielsen.

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Vestas CTO Anders Nielsen | 'There's a technology race out there and we know how to run it'