Sif, KCI and Smulders seek to revive tripod offshore wind foundation

Dutch and Belgian engineering firms are developing a new tripod foundation design to rival monopiles in offshore wind farms built in water depths of at least 50 metres.

Sif, KCI and Smulders believe their new design would be sturdier than monopiles and easier to manufacture than jacket foundations – both of which are more commonly used.

The tripod design would feature three pins, in a triangle formation around a central column, driven into the seabed. There would be six bracings connected to both the pile sleeves and the central column.

They plan to produce the foundations’ central columns in Roermond, Netherlands, where Sif is based, and source bracings from UK suppliers.

The partners will then integrate all of the foundations’ components at Smulders’ site in Wallsend in north-east England.

They are currently investigating the feasibility of the foundations, and plan to map out a route to certification by the end of the year. However, the partners do not believe a demonstrator project will be necessary as the foundation-type has previously been used at German offshore wind farms.

Serial production is due to start in 2024.

Foundation competition

A tripod foundation was last deployed offshore at the 400MW Global Tech I Global Tech I (400MW) Offshoreoff Cuxhaven, Germany, Europe Click to see full details wind farm, which was commissioned in 2015, the engineers claimed. It has not been used since then as it was not competitive with monopiles in the lower water depths used in that era, the partners explained.

However, fixed-bottom foundations are now being used in ever greater water depths in the northern North Sea basin – including up to 120 metres – with jackets as a complementary foundation choice in greater depths.

They believe their tripod design would be more commercially viable than new foundation concepts or floating wind, given its track record in the German market. Tripod foundations have also been used at the 200MW Trianel Windpark Borkum I Trianel Windpark Borkum I (200MW) OffshoreNorth of Borkum, Germany, Europe Click to see full details and 62MW Alpha Ventus Alpha Ventus (62MW) OffshoreNorth of Borkum, Germany, Europe Click to see full details German offshore wind farms, according to Windpower Intelligence, the research and data division of Windpower Monthly.

Sif’s product strategy director Michel Kurstjens told Windpower Monthly that monopiles become exponentially heavier in greater water depths, and jackets remain expensive and cannot be produced quickly – increasing tripods’ advantage over the two technologies.

He added that the partners expect to use cheaper welding and fabrication methods than are used for jackets and use less steel than is needed for monopiles – driving down total costs for tripod foundations.