Innogy and Shell Back Stiesdal’s TetraSpar Concept

Innogy, Shell and Stiesdal Offshore Technologies A/S (SOT) have signed an investment and cooperation agreement to build a demonstration project using SOT’s TetraSpar floating foundation concept.

The demonstration project will feature a 3.6MW Siemens Gamesa direct-drive turbine due to be deployed in 2019 at the test site of the Marine Energy Test Centre (Metcentre) near Stavanger, Norway, in water depths of 200m.

The foundation will be manufactured and assembled in Denmark, with the turbine installed in the port of Grenaa, from where it will be towed to the project site some 10km off the coast, moored to the seabed with three anchor lines and connected to the electrical grid.

According to innogy, the modular layout comprises a tubular steel main structure with a suspended keel, expected to offer important competitive advantages over existing floating wind concepts, with the potential for leaner manufacturing, assembly and installation processes with lower material costs.

“These are exciting times. The floating offshore wind market is evolving but until now, floating foundations have been stubbornly expensive. This demonstration project will give us a better understanding of how the cost can be driven down,” said Hans Bünting, COO Renewables of innogy SE.

“The industrialised approach of the TetraSpar design, combined with innogy’s experience in delivering offshore wind projects, will enable large-scale, cost-effective deployment of floating wind projects around the world.”

The parties plan to establish a company for the development of the project in which innogy and Shell will each hold a 33% share, with SOT and its parent company Stiesdal A/S owning the rest. The project budget amounts to circa EUR 18 million.

The TetraSpar floating wind foundation was developed by Henrik Stiesdal, a Danish inventor and former Chief Technology Officer at Siemens Wind Power. In October last year, the concept secured a DKK 9 million grant (approx. EUR 1.2 million) through the Danish Energy Technology Development and Demonstration Program (EUDP).