IN DEPTH: French push floating wind

The offshore wind industry may be seeing the start of a French revolution – until now a quiet one – in deep-water turbine design.

At the recent Thetis ocean energy conference in Brest, French naval contracting giant DCNS took to the dais to say it would have a 1MW prototype of its WinFlo floater concept, being developed with Nass&Wind, moored at the grid-connected SEM-REV wave and wind energy testing facility off Le Croisic on the Brittany peninsula by next year.

The aim is to eventually scale-up the concept, a two-bladed turbine set atop a triangular semisubmersible platform fixed to the seabed using catenary cables, to a 5MW version.

“The decision to build the WinFlo demonstrator is testimony to the technology’s maturity,” says DCNS of the project, which had partners including compatriots Vergnet, Ifremer and engineering school ENSTA Bretagne.

Nass&Wind already has a seat at the French offshore table after joining up with France’s EDF EN and Danish group Dong for the Saint-Nazaire project awarded in the country’s first call for tenders in 2012.

The 2MW VertiWind prototype from Technip should beat it into the water. The first fruit of a collaboration between the French offshore oil and gas engineering giant and start-up Nénuphar, the vertical axis machine, tested for several years on land, is under construction for float-out in the autumn in the Mediterranean.

The diagonally bladed concept, designed for deep-water use, is on the fast track. The companies plan to have a 25MW development consisting of 13 full-scale “multifloater” units on line by 2015.

Another French floating wind turbine platform, designed by Ideol, has meanwhile bagged €7m from venture capitalists to industrialise its innovative concrete concept, as part of a 2MW part-scale demonstrator being built with turbine maker Gamesa and Stuttgart University under the EU-backed €36m FloatGen project.

Ideol’s floater is based around a square, open-centred platform moored to the seabed using a catenary-style spread of chain lines, or hybrids of chain and synthetic rope, with “soil-specific” anchors.

A first FloatGen – ultimately foreseen for mega-class turbines of up to 10MW in deep water locations but is expected to be competitive with seabed-fixed technologies in depths of 35-40 metres – is on the cards for 2015.

The market for floating wind turbines off France awaits. Expectations are that by 2030, floating wind farms could be sending ashore some 20GW of electricity, supercharging the 3GW to be brought online through its first two licensing rounds to meet the government’s 2020 target of 6GW installed capacity.

There is, of course, a further, long-term benefit to the build-out of floating wind farms in French deep water. That is construction of the industrial facilities – such as Alstom is building in the ports of Cherbourg and Saint-Nazaire for its 6MW Haliade turbine needed to underpin such an offshore campaign, and the supply chain that will grow up around it.

The business model is straightforward. As DCNS puts it: “The production and marketing of Winflo structures and turbines will contribute directly to the establishment of a French industrial base specialising in floating turbine technologies, and subsequently to international sales.”