Few floating wind power prototype launches are more keenly awaited than that of the TetraSpar, the brainchild of wind pioneer Henrik Stiesdal.

His design, a revolutionary modular tubular steel structure with an innovative underwater triangular float, could – as with many of Stiesdal’s hundreds of patented technologies – be market-disrupting.

The concept, a prototype of which is slated to be installed off Norway next year as a 3.6MW unit takes a novel tack on floating wind: it starts from piece-work fabrication of steel component parts “that could be manufactured in just about any factory”, with all elements shipped to a quayside for assembly and outfitting with a turbine.

During construction, the “ float keel” is retracted and stays up during tow-out to project site, where it is then lowered using air-filled ballast tanks to provide deep-draft stability for the unit at sea.

“This is about getting the manufacturing costs down to optimal levels for industrialisation,” says Stiesdal. “And part of this is about finding a solution to the project time currently associated with building the current generation of floating wind foundations, which is generally seen as unsustainable.” Units can take 12-15 months to build, versus the “several a day” promised by some new-generation models.

“Bringing in Innogy and Shell as investors [for the prototype project] means we now have a partner that has a long track-record in offshore wind power [Innogy] and also one that comes from the oil & gas industry with a lot of knowledge of floating structures, more than is common in the wider offshore wind industry where this experience has yet to be built up.”

Stiesdal’s “industrialisation-minded” methodology will be tested for the first time this summer, as steel components are fabricated at Welcon’s factory in Give, Denmark, before being transported to the Port of Grenaa for assembly, topped with a turbine, and towed to the 40MW MetCentre test site off the Norwegian island of Karmøy, for mooring and connection to the grid.

“Having the huge competencies of Innogy and Shell and their input has resulted in our getting a lot better ‘product’ than we would have had otherwise,” states Stiesdal, highlighting contributions from the two partners in the areas of industrial transport logistics and subsea engineering.

For Innogy, the interest in floating wind travels far beyond the prototype project. “If we have ambitions to grow not just in Europe but worldwide then we will need more than just bottom-fixed foundations,” says Martin Ferreira, Innogy’s head of offshore investment & asset management. “The water depths in many of the countries we are looking at determine this – we will need floating to open up new markets..

“The TetraSpar can be built in any of a number of regions in the world, doesn’t need specialist manufacturing sites, can be assembled quayside and installed without the high-price [wind turbine installation] jack-ups. Taken together, we are excited to investigate how to take this technology further and faster.”

Stiesdal adds: “Floating has the potential to ‘leapfrog’ conventional offshore wind in many markets. And it will be a necessity if we are to decarbonise the world in time [to avert climate catastrophes].”

Next wave of floating wind begins to build