IN DEPTH: Get ready for the next wave of floating wind

Five years ago, floating wind power was a futurist’s dream symbolised by a solitary 2.3MW turbine turning in the stormy wilds of the Norwegian North Sea.

Darius Snieckus

Today, the sector is on the cusp of a great leap forward into industrial reality, with the 3.4GW foreseen to be switched on by 2030 pointing the way towards eventually harnessing hundreds of gigawatts of energy with floaters anchored around the world.

Despite this promise, progress so far has been hard-won. The utility-scale prototypes installed to date — Hywind 1 off Norway, WindFloat 1 off Portugal and a trio of multi-megawatt machines off Japan — are a drop in the ocean compared to the seven terawatts of global potential gusting over water depths of 50 metres or more.

But with capital costs being continually pared down, the economics of these revolutionary demonstration units are improving markedly, setting the example for the first bona fide commercial arrays that will add over 200MW to the global offshore wind fleet by the end of the decade.

“There is a very strong opportunity for floating wind going forward, even if it will still take some time before the sector becomes a key contributor [to offshore wind-power production] overall,” says Michael Gulbrandtsen, senior consultant at Denmark’s MAKE. “There are good indications that the cost can be brought down significantly but it will also take a tremendous effort the length of the supply chain for floating wind to reach real commercialisation.

“Japan and France look like being the leading markets, and the UK could play an important role — though [in Britain] a good deal more support is needed for it to get started. The US too, in the longer term, could be a very interesting region for floating concepts.”

Japan — despite time and cost overruns on the high-profile Fukushima Forward (FF) project — is emerging as the most bullish market over the coming decade, with MAKE expecting to see 2.4GW of floating wind installed there by 2030.

Everything in Japan hinges on FF. The project, jump-started after the Fukushima Daiichi nuclear disaster in 2011, has moored three units some 30km offshore in water depths down to 150 metres: a Hitachi 2MW turbine mated with a Mitsui Zosen semi-submersible foundation; a spar-based substation; and, this past summer, the 7MW Shinpuu, an advanced semi topped with MHI’s SeaAngel turbine, due for belated switch-on by the end of this year. The fourth unit, Hamakaze, an innovative 5MW Hitachi downwind machine to be set atop a Japan Marine United “compressed spar” floater, is due to start producing power by next May.

“Technically and technologically, the project has been progressing smoothly,” says Marubeni’s Tommy Fukuda, who is project director at the consortium-run FF. “We have seen over 90% availability from the [2MW] Hitachi turbine and capacity factors of over 30%. This is for a demonstration unit — it proves that [floating wind power] works off Japan.

“The only problems have been commercial ones. We need to bring down the [capital] costs.”

This is not a case of a few yen here or there. The FF units were developed at a capital expenditure of $20m/MW — compared to the current $3m/MW for onshore wind. The target, as set by government R&D body Nedo, is for floating wind capex to be brought down to $6m/MW. Set against a capacity factor around double that of Japanese onshore wind’s 20%, this would make floating wind economic as a grid-connected energy supply.

“More compact, lighter, much less expensive designs with lower construction costs are needed for the future to achieve a competitive cost,” says Fukuda.

The future is fast approaching in Japan. The government has previously announced it aims to have a 1GW floating wind farm ready to be showcased at the 2020 Olympic Games in Tokyo. Some observers have suggested 100MW might be more likely.

As Japanese Wind Energy Association general manager Yoshinori Ueda notes: “It is difficult to say now [whether or not] 2.4GW of floating wind power [could be] installed by 2030 or 1GW by 2020 because of the uncertainty of the cost. It needs lots of effort for cost reduction from the experience at Fukushima [Forward].”

Halfway round the world in Scotland, Norwegian oil giant Statoil is preparing to take a final investment decision on what is likely to be the world’s maiden floating wind array. The Oslo-headquartered company, an offshore wind trailblazer with fixed-foundation projects such as Sheringham Shoal and Dudgeon, is “weeks” away from a final investment decision on Buchan Deep. This 30MW project off Peterhead, eastern Scotland, would be made up of five second-generation 6MW Hywinds daisy-chained together in 90-120 metres of water.

“Commercialisation of an industry is a lengthy and capital-intensive process,” says Trine Ingebjorg Ulla, head of business development for Statoil New Energy Solutions. “The next and necessary step in scaling up to larger dimension, multi-turbine parks is now close to being realised, and we foresee that commercial-scale [floating] wind farms could start emerging after 2020.”

Europe’s place as the spiritual home of offshore wind will be enshrined by other floating arrays now taking shape, one off Portugal — consortium WindPlus’ 25MW WindFloat Atlantic project — and another off Scotland, Pilot Offshore Renewables’ 50MW Kincardine. The two are in line to be the next step up for US technology developer Principle Power’s WF1 concept, the 2MW prototype of which has been turning since 2011 in the Portuguese Atlantic.

“A few years ago, this was an industry of very few players, pioneers trying to demonstrate that floating wind makes sense, that it works,” states EDP Renewables’ (EDPR) Carlos Martin Rivals, project director for WindFloat Atlantic, which is being developed by a consortium that includes Principle Power, Spanish energy company Repsol and Japanese-Danish turbine maker MHI Vestas.

“This the second phase. People are convinced now; the market is growing and diversifying a lot. The third phase is coming: a few concepts will turn commercial and governments will start leasing areas for deepwater wind exploration and utilities, like us [EDPR], becoming interested in using these technologies in a commercial way.”

Martin is struck by the speed of economic improvement in floaters such as WindFloat. “When you compare WF1 to WindFloat Atlantic and increase the size of the turbine and take many of the costs of fixed units [chiefly installation-related] and you spread them across a large number of floating units, it is quite impressive how close you get to costs associated with fixed.”

The wider sector is keeping pace. “There are things happening now that 18 months ago few were expecting,” notes Principle Power chief executive João Metelo. “The number of players that are coming into the sector, the growing financial support, everything that is happening in France... it all pushes the discussion [about the viability of floating wind] to a different level.”

France is the sleeper in the floater space. With no fixed-bottom turbines yet erected off its coasts, the French government has nonetheless set an aspirational target of having 600MW of floaters running by 2030, starting with 100MW of demonstrator units. The ambition, says Frédéric Lanoë, president of industry body France Énergie Éolienne, reflects both the “large appetite” for technology innovation in the country and the need for floating concepts if it is to generate power in the deep waters of the French Mediterranean and Atlantic.

“Just 1km off the coast of the Mediterranean port of Toulon, waters are already 100 metres deep; off the coast of Brittany in the Atlantic you have a similar situation — floating turbines are the only solution,” he notes, adding that local players such as naval giant DCNS and floating wind technology start-up Ideol are “pushing hard” to make the case for developing a home-grown industry.

“We also realise that something extremely big is happening with renewables and France needs to catch up. Floating offshore is a chance to be a pioneer worldwide.”

Along with DCNS, which has an advanced semi-sub concept dubbed the SeaReed under development with Alstom for the latter’s 6MW machine, Ideol is jockeying into position as a serious contender as a leading floating wind developer.

Construction of a flagship unit based on its semi-submersible “damping pool” foundation, being developed under the European Commission-funded FloatGen scheme, starts this winter in St Nazaire, France, and an engineering deal is in place with Japanese industrial conglomerate Hitachi Zosen for both concrete and steel versions slated to be in the water by 2017.

“Our concept is not the product of an inventor’s pride or some long industrial heritage, it is about building a foundation that meets market needs,” says Bruno Geschier, Ideol’s chief marketing officer. “[We are] somewhat different from other players in that we are arguably the only [floating wind turbine] company today that is earning money through sizeable commercial contracts; we are not dependent on subsidies.”

Ideol’s shallow-draught, open-centre concept is set to make its debut at a test site off Le Croisic, in the French Atlantic next year, topped with a soon-to-be-announced multi-megawatt turbine, next summer. But it has also been chosen as the foundation for a major European joint industry project developing designs for 10MW turbines aiming to be optimised and qualified by early 2017.

“The challenges facing the sector now have little to do with those challenges we had two or three years ago, where the majority of the most seasoned turbine designers and developers were saying ‘never’ to floating wind,” adds Geschier. “Those same companies are seeing it very differently now. The largest German developers are coming to us now for discussions about deploying in waters we would class as ‘shallow’.

“The real challenge now is making the economics of 7-8MW units work on much more compact, less expensive, more flexible foundation solutions, for water depths of 28 metres and deeper.”

Joining Ideol’s are a number of other prototypes — including the SOF from Germany’s Gicon, soon to be switched on in the Baltic Sea; Aqua Ventus’ VolturnUS, to be upscaled from its operational 1:8 scale prototype off the northeast US; and the TLPWind unit being developed by Spain’s Iberdrola for installation off Scotland in 2018.

“There will doubtless be many new concepts coming in the future, but for the time being it is important we keep a balance in focusing on the ones that are already pretty mature, as well as financing the best new ideas emerging now,” states Guldbrandtsen.

Former Siemens Wind Power chief technology officer Henrik Stiesdal has just unveiled his own design, the In-Float, that tackles floating turbine foundations’ “main issue” of having to carry the colossal weight of both foundation and turbine. The lightweight “industrialisable” 6-10MW concept features innovative, low-price flotation tanks supporting a slimline steel frame and tower structure.

Two floating wind market reports published out of the UK this year, one from government-industry body the Carbon Trust for the Scottish government and the other from R&D agency the Offshore Renewable Energy Catapult, both herald a sector that could be producing at near-shore, deepwater sites at a levelised cost of energy as low as £85 ($131) per MWh in the 2020s.

The Carbon Trust analysis of the current project pipeline for floating wind forecasts a “modest” deployment of 200-300MW by 2020, consisting mostly of single prototypes and pilot projects.

“From our perspective, commercially feasible solutions can be pushed forward by proving in established markets that the levelised cost of energy could be lower in near-shore, deepwater locations with high wind resource, as opposed to more challenging far-from-shore sites — due to transmission, accessibility, and other issues,” says senior manager Marc Costa Ros.

Floating wind power’s next generation has its work cut out. But it is gathering momentum, refining its engineering, and moving unflaggingly towards commercialisation.

“I am still somewhat frustrated by how slowly things are progressing, but at the same time the first projects are moving ahead, and it will be great for the industry to see full-scale units being built for a pilot project [such as Buchan Deep or WindFloat Atlantic],” says Johan Sandberg, floating wind turbine technology segment leader at DNV GL, which is providing “high-level verification” of Stiesdal’s In-Float design.

“Industrial development is an iterative process, and politics and technology development go hand in hand. And if there is insufficient support from government right now, the sector will not advance as rapidly as it might.”

The magic £100/MWh cost of energy remains the floating sector’s unofficial 2020 target. Martin believes it is very much still possible. “With existing technology [floating wind] is quite competitive already. We are climbing a technology curve, with still many improvements to be implemented. And from an operational standpoint, floating wind is already lower-risk than many fixed-foundation projects, in terms of installation and O&M. This is big. And these things are becoming better understood. [Floating wind] is becoming bankable.”