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Prysmian contributed to the development of the grid connection of the DemoSATH floating wind turbine project

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Prysmian contributed to the development of the grid connection of the DemoSATH floating wind turbine project.

The 2 MW pioneering experimental platform developed by Saitec Offshore Technologies, located off the coast of Biscay, will be a pilot project for SATH technology and will allow to acquire knowledge for future large-scale developments of floating offshore wind energy in deep coastal waters, as an alternative to bottom-fixed applications.

The DemoSATH floating wind turbine, developed by Saitec Offshore Technologies in collaboration with the German company RWE Offshore Wind and the Japanese company The Kansai Electric Power Co. Inc., was successfully installed in the Bay of Biscay. The installation marks a milestone in the implementation of a new type of platform for floating offshore wind turbines in deep coastal waters, using SATH technology. The prototype was anchored at an 85-metre depth last August at the BiMEP test area, 2 miles off the coast of Armintza, Biscay, and will generate 2 MW of renewable energy.

Prysmian participated in the project contributing all its expertise and experience, acquired over many years in the development of solutions for floating offshore oil platforms and submarine umbilical cables. All this, together with its outstanding R&D resources and production capacity, made it possible to achieve this challenging milestone in the use of this type of technology and to provide a tailor-made solution in terms of cables, accessories and services.

Prysmian did not hesitate to play a facilitating role in this highly challenging project, in line with its strategy aimed at being a key player in the energy transition and electrification of our society.

What is it like to develop this kind of dynamic cable?

Firstly, it is necessary to receive and analyse data on the requirements that cables and systems will have to meet in a specific ocean location once they are connected to a given float model. A draft design is then prepared based on all the experience gained by Prysmian, which, through the generation of a specific software model, will carry out the engineering study. This study will simulate a wide spectrum of parameters, including the characteristics of the seabed or the extreme environmental conditions to which the cables will be subjected throughout their lifecycle and which will influence the systems’ functionality and the project’s feasibility and profitability.

In a second phase, once the engineering study has been completed, the proposal is submitted. In this specific case, a 15kV three-core copper dynamic cable with a special double steel armouring (which provides greater mechanical resistance to extreme events), consisting of a metallic braid screen to better withstand the continuous bending to which the conductors are subjected for more than 25 years. The cable is also equipped with embedded fibre optics enabling offshore-to-onshore communication.

Finally, once the cable design and the lazy wave configuration (i.e., cable configuration where the intermediate section of the cable is equipped with buoyancy modules that allow the cable to achieve a waveform, thus reducing the tension and bending by absorbing the movements of the floating platform and the waves) have been validated, the necessary specific amount of cable is manufactured. In this case, production was assigned to the manufacturing plant in Vilanova i la Geltrú, Spain.

As an anecdote, it should be noted that the engineering study was carried out also taking into account the growth that will develop on the cable (mainly molluscs, due to the difference in temperature with seawater) and the consequent increase in the cable weight over time.

This floating structure, with its innovative single-point mooring anchoring system consisting of six hybrid chain and fibre lines, has been the successful result of years of research and experience by the alliance formed between Saitec Offshore Technologies, RWE Offshore Wind and Kansai Electric Power. This alliance has received institutional support from the Centre for the Industrial Technological Development (CDTI) and the Basque Government, and has involved the participation of various companies in the industrial and technological ecosystems, including Ormazabal. With the installation and connection of DemoSATH, an operational phase will begin, generating electricity and collecting valuable information about the behaviour of the SATH platform. The floating wind platform has been designed and equipped to harness wind power in deep coastal waters and convert it into clean and renewable energy. This pioneering FOW technology has great potential to reduce carbon emissions and to contribute to the renewable energy goals of Spain and other countries around the world.