World’s first twin-headed floating wind concept sets sail

The world’s first twin-rotored floating wind power platform is on track to be moored offshore “in the coming weeks”, following finalisation of the assembly of EnerOcean’s innovative W2Power prototype on the Spanish island of Gran Canaria.

Built at the Astican shipyard near Los Palmas, the 1:6 scale unit – a triangular steel semisubmersible with angled turbines at two corners that ‘weathervanes’ into the wind – will be put through its paces in 65 metres of water in a three-to-four month fast-track testing programme, as the developer ramps up plans for a maiden full-size array.

“Our first W2Power prototype platform, the result of more than ten years of systematic research and technological innovation, ... is a very important milestone for us and the wind energy sector as a whole, as we progress toward greater efficiency and cost-effectiveness,” said EnerOcean president Pedro Mayorga.

The W2Power concept, which has gone through several incarnations since being launched in 2009 as a hybrid offshore wind-wave power design, is engineered to support a pair of “off the shelf” 6MW turbines, giving each unit a 12MW nameplate capacity.

“We want to show that our concept, with its two turbines, can be built on a light, robust platform ... [and that] there is high value in generating high power from this design, which includes some real innovations in terms of the weathervaning and the leaning towers that allows [the rotors] to reach-out beyond the base of the platform,” he told Recharge.

The 40-tonne prototype, which will fly two “generic” 100kW machines, has a shallow-draft design that can be “adjusted to get in and out of harbour”. At full-scale, the W2Power platform is conceived of for a “sweet spot” of water-depths ranging from 35-300 metres.

Mayorga said the tow-out would be “very soon” but hinged on finding a clear weather window for installation.

Jan Erik Hanssen, part of the project team that devised the W2Power concept and co-founded EnerOcean, said the launch of the prototype was “a major step forward” for the technology.

“We didn’t want to join the choir of [floating wind power companies] that were all trying to raise money with PowerPoint presentations. So we went ‘semi-stealth’ and kept working our way forward with this design, very methodically, step-by-step, and now we are putting it in the water. This is a watershed. And the market, we know, is really looking for this now.

“This prototype wasn’t optimised to see what power production we could get out of a small platform,” he noted. “What we prioritised was that the turbines would behave like [6MW units], with control systems managing the pitch and so on.”

Alex Fairtlough, CEO of aerospace and wind energy engineering group ISATI, EnerOcean’s first industrial investor, added: “At base, we are talking about reducing cost – that’s what's going to make a success of floating wind – and in aerospace engineering we have see that commercial success is not about being the biggest and the fastest, it’s the simplest. We believe this is something W2Power represents [to the offshore wind industry].”

Once the W2Power prototype is field-proven, EnerOcean aims to build a 3-5 unit development of up to 60MW, dubbed CanArray, off the Canaries, that could produce power at €100/MWh ($113/MWh). Commissioning of the project, expected to cost €140-€170m, could be as early as 2021.

“The Canary Islands government is in a unique position to be a global pioneer in realising the potentially vast opportunities of wind energy in deep waters,” said Fairtlough.

“I have seen how seriously Japan is considering the opportunity, including in innovative combination with fish farming, and it would be very interesting to see the Canary Islands also becoming a leader and role model for other deep-water areas.”

Hanssen added: “ There is enormous potential for W2Power, as the lowest-cost floating solution, to unlock new markets for wind power across the globe, including in the deep waters of Japan, Pacific North America and the UK.”

Latest calculations from wind industry advocacy body WindEurope suggest some 350MW of floating wind capacity will be switched on in Europe by 2021 via a raft of projects off the UK, France, Portugal and Norway.

From a single industrial-scale prototype in 2009, floating wind has progressed at a clip toward commercialisation. Many analyst forecasts, including those of UK low-carbon business development body Carbon Trust, point to a fleet as large as 15GW by 2030.