This paper documents the round robin testing campaign carried out on a floating wind turbine as part of the EU H2020 MaRINET2 project. A 1/60th scale model of a 10 MW floating platform was tested in wave basins in four different locations around Europe. The tests carried out in each facility included decay tests, tests in regular and irregular waves with and without wind thrust, and tests to characterise the mooring system as well as the model itself. For the tests in wind, only the thrust of the turbine was considered and it was fixed to pre-selected levels. Hence, this work focuses on the hydrodynamic responses of a semi-submersible floating foundation. It was found that the global surge stiffness was comparable across facilities, except in one case where different azimuth angles were used for the mooring lines. Heave and pitch had the same stiffness coefficient and periods for all basins. Response Amplitude Operators (RAOs) were used to compare the responses in waves from all facilities. The shape of the motion RAOs were globally similar for all basins except around some particular frequencies. As the results were non-linear around the resonance and cancellation frequencies, the differences between facilities were magnified at these frequencies. Surge motions were significantly impacted by reflections leading to large differences in these RAOs between all basins.

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Abstract. The global floating offshore wind energy industry is rapidly maturing, with several technologies having been installed at pilot and demonstration scales. As the industry progresses to full array-scale deployments, the optimization of marine activities related to installation, operation and maintenance, and decommissioning presents a significant opportunity for cost reduction. This paper reviews the various marine operations challenges towards the commercialization of floating wind in the context of spar-type, semi-submersible and tension leg platform (TLP) technologies. Knowledge gaps and research trends are identified along with a review of innovations at various stages of development, which are intended to widen weather windows, reduce installation costs, and improve the health and safety of floating-wind-related marine operations.

Marine renewable energy (MRE) is still an emerging technology. As such, there is still a lack of mature standards and guidance for the development and testing of these devices. The sector covers a wide range of disciplines, so there is a need for more comprehensive guidance to cover these. This paper builds on a study undertaken in the MaRINET2 project to summarise recommendations and guidance for testing MRE devices and components, by reviewing the recently published guidance. Perceived gaps in the guidance are then discussed, expanding on the previous study. Results from an industry survey are also used to help quantify and validate these gaps. The main themes identified can be summarised as: the development progression from concept to commercialisation, including more complex environmental conditions in testing, accurately modelling and quantifying the power generated, including grid integration, plus modelling and testing of novel moorings and foundation solutions. A pathway to a standardised approach to MRE testing is presented, building on recommendations learnt from the MaRINET2 round-robin testing, showing how these recommendations are being incorporated into the guidance and ultimately feeding into the development of international standards for the marine renewable energy sector.

The EU H2020 MaRINET2 project has a goal to improve the quality, robustness and accuracy of physical modelling and associated testing practices for the offshore renewable energy sector. To support this aim, a round robin scale physical modelling test programme was conducted to deploy a common wave energy converter at four wave basins operated by MaRINET2 partners. Test campaigns were conducted at each facility to a common specification and test matrix, providing the unique opportunity for intercomparison between facilities and working practices. A nonproprietary hinged raft, with a nominal scale of 1:25, was tested under a set of 12 irregular sea states. This allowed for an assessment of power output, hinge angles, mooring loads, and six-degree-of-freedom motions. The key outcome to be concluded from the results is that the facilities performed consistently, with the majority of variation linked to differences in sea state calibration. A variation of 5–10 % in mean power was typical and was consistent with the variability observed in the measured significant wave heights. The tank depth (which varied from 2–5 m) showed remarkably little influence on the results, although it is noted that these tests used an aerial mooring system with the geometry unaffected by the tank depth. Similar good agreement was seen in the heave, surge, pitch and hinge angle responses. In order to maintain and improve the consistency across laboratories, we make recommendations on characterising and calibrating the tank environment and stress the importance of the device–facility physical interface (the aerial mooring in this case).