Siemens Gamesa’s hotly anticipated ‘1X’ offshore wind turbine concept – widely expected to be one of a fleet of next-generation machines in the nameplate range of 14-16MW – is moving ahead following the filing of a patent application staking its claim on a number of future-looking blade and rotor innovations that might be considered for the technology on its way to launch in the mid-2020s.

But the OEM’s head of offshore technology, Morten Pilgaard Rasmussen, said a US patent applied for this month that included a new-look cable-supported rotor-star design was “not part of plans for the next two or three years”, and though “there were no issues” around evolving its longest blade, the 94-metre B94, for a rotor bigger than its largest-to-date, the 193-metre-diameter concept flown by its top-of-the-line turbines, the filing was only “for an idea that [the company wanted] to try and protect”.

Rasmussen, speaking exclusively with Recharge, said that Siemens Gamesa’s far-horizon technology development strategy saw “value at times [in] investing in technologies that are ‘disruptive’”, yet stressed the evolutionary nature of the process, pointing to its recently unveiled 10MW turbine, the SG10.0-193DD, which has already been uptuned to an 11MW version, the prototype of which was “a few weeks off” from commissioning in Osterild, Denmark.

“The time that this industry would need for everyone to accept [a technology such as a cable-stayed rotor] in large sales contract is a long time, but we still need to be early out with the technology and bring our good ideas at least on paper,” he said.

“Our product development requires that we typically look four-to-five years ahead, and with some technology we extend that to more like five-to-ten years. The patent that is out in the public [domain] is part of that.

“So it is not that we have plans to include [cable-stays] in our rotor design, but we are trying to prepare for a future where blades will become more complicated, and of course longer, and so more difficult to manage in terms of loads and so on.”

The patent application seen by Recharge, which in fact is based on one first filed in 2016, focuses chiefly on new internal structural elements for an ultra-long blade that is designed to provide “non linear resistance to bending”, but includes a figure depicting a rotor-star with six cables connecting the hub to the blades.

Philip Totaro, CEO of industry intelligence consultancy IntelStor, said its calculations suggested existing glass and carbon-fiber blade manufacturing methods “would not allow the loads to be easily handled given the weight of a blade that would be over 120 meters in length, necessitating the cable-stays.

“Currently, we believe this to be the most economical solution to that loads challenge.”

He noted, however, that there were “non-cable-stay alternatives” that were being explored based on a technique of “effectively bonding a metal matrix composite in the blade root where you need stronger material for bending loads to a carbon-fiber composite in the outboard section where you want lightweight strength”.

Stefen Poulsen, Siemens Gamesa’s head of offshore technology development, said that the development of blade technology at Siemens Gamesa – which is rooted in the legacy of the highly regarded IntegralBlade concept used for its B75 and B81 models – still had room to evolve further for larger turbines.

“Over the last many years we have moved back the boundaries year after year by technology development. So with by same blade technology [as used on the B94 model] and interfacing with the various [turbine] components, the design has been largely unchanged – and this has been done by using different materials better, for instance,” he told Recharge.

“But of course, we are also always searching for where there may be a technology ‘boundary’ at some point, and this is where we challenge ourselves on not only the blade but also on how the rotor as a ‘system’ should be developed going forward.”

The ‘1X’ has achieved near-mythological status in the offshore wind industry since the first mentions of the concept in 2015, with the mystique only growing as Siemens Gamesa has up-scaled its turbine nameplates from 6MW skyward. The 10MW model, revealed exclusively by Siemens Gamesa CEO Markus Tacke to Recharge last year and now uptuned to 11MW, is said to be designed to serve to “bridge market demand” until the new top-of the-range model is in showrooms in 2024-25.

Vattenfall announced in November it would use 140 of the SG11.0-193DDs for its Hollandse Kust South 1 to 4 projects off the Netherlands.

Rival OEM GE has its 12MW Haliade-X prototype up and turning in the Port of Rotterdam in the Netherlands, with first orders in the bag for the world’s biggest offshore wind farm, Equinor-SSE’s 3.6GW Dogger Bank off the UK, as well as for Orsted’s 1.1GW Ocean Wind and 120MW Skip Jack projects in the US Atlantic.

GE, along with the third member of the big three offshore wind turbine makers, MHI Vestas – which recently started-up its 9.5MW prototype, also at Osterild, and has a 10MW model signed up for use on projects including the 30MW Gulf of Lion floating project off France, is also understood to be looking at upscaling its turbine design to 14MW-plus, as it is widely expected machines of this size will be needed to make the economics of the coming wave of zero-subsidy projects off Europe viable.

The International Renewable Energy Agency has predicted the global offshore wind build-out could reach 1TW of plant by 2050. And the World Bank produced a study late last year that suggested “emerging” plays alone could ultimately add as much 3TW to the worldwide fleet.

A recent report from European wind advocacy body WindEurope pointed to Europe alone seeing its offshore wind plant base growing to 450GW by mid-century and meeting 30% of the continent’s power demand.