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Testing tomorrow’s offshore wind technology

“Our main aim is to see the turbine out at sea and producing energy”, says Olav Weider, Managing Director at the Norwegian company Dr.techn.Olav Olsen AS. “Clean energy for the world. We believe that offshore wind has an important part to play in the green transition, and this is a milestone on the road towards that aim”, he says.

There are only a few floating wind turbines in the world at present. This autumn, Statoil installed the first wind farm consisting of floating turbines off the coast of Aberdeenshire in Scotland. Many more players are now entering the scene, all in the hope that technological advances will help to reduce costs and increase energy production.

“We believe that offshore wind has a big future”, says Leif Delp, a Project Director at Statoil. “We are now on the start line in terms of concept development”, he says. “Clearly we need to optimise our concepts and achieve better profitability, and this process is now under way. As more players enter the scene, perhaps coming up with new and exciting projects, we will definitely see dramatic reductions in the costs associated with power generation from floating wind turbines”, says Delp.

Long-lived concrete structures

Representatives of the industry and researchers met recently at SINTEF Ocean’s SeaLab facility where the final model tests of Dr.techn.Olav Olsens innovation were being carried out. The model was tested under normal current, wave and wind conditions, and was also subjected to extreme weather testing. The unique aspect of the company’s concept is that the turbine is of concrete construction. It is thus anticipated to have a long life with little need for extensive maintenance.

“We believe that the mass production of floating wind turbines will be easier than for fixed structures because the latter have to be specially tailored to the seabed conditions and water depths at the locations where they are installed”, says Weider. “Floating turbines can be much more adaptable in terms of their location”, he says.

Researchers at SINTEF are receiving an increasing number of requests from wind energy generating companies regarding the further development and testing of technologies for application in offshore energy production. The EU project LIFES50+ has enabled SINTEF’s team to develop a unique test method called “Real-Time Hybrid Model (ReaTHM®)”.


Model test tailored to offshore wind

“The wind turbine is exposed to physical waves and currents, and simulated wind loads – all in real time”, says Maxime Thys, a researcher at SINTEF Ocean. “The method provides considerable flexibility and reduces costs”, he says. “Costs are lower because we don’t have to design and build a rotor for the model. Flexibility is achieved because we can supply wind from various directions and can also simulate extreme conditions which it may be dangerous to implement using a physical model with a rotor”, he says.

The turbine tested at SINTEF was a 10 megawatt facility designed for installation in about 130 metres of water offshore Maine in the US.

“Statoil has prepared the ground with its own Hywind turbines”, says Weider. “A lot is happening in France, Japan and other places around the world. Offshore wind generation has been talked about for a long time, and is now becoming a significant market”, he says.

Phase one qualification performed

The overall concept rankings were based on  analysis of Levelised Cost of Energy (LCoE), Life Cycle Assessment (LCA) and Risk evaluation determined by the LIFES50+ Overall Evaluation tool named “Floating Offshore Wind Assessment Tool” (FOWAT).


The Overall Evaluation determined that Iberdrola’s TLP and Olav Olsen’s concrete semi-sub concepts should be selected for Phase II (Concept optimisation) of the project, where they will undergo further studies and optimization in order to verify that the concepts can accommodate a 10MW wind turbine in a cost effective way.

Experimental results from Hardware-in-the-Loop Model testing at SINTEF Ocean’s ocean basin in Trondheim and Politecnico di Milano’s wind tunnel in Milan will be used for further development and verification of the technologies using numerical simulation tools. The innovative concepts will be further developed, technically and economically, to reach a higher technology readiness level. The ultimate goals are to facilitate innovation, reduce risk, and reduce the LCOE, and the uncertainties associated with its estimation.

The evaluation process was subject to strict governing criteria to determine the outcomes and does not constitute any form of approval, verification or certification of the selected designs.

Phase One – Evaluation of the concepts

The four initial innovative concepts selected as part of the project are at TRL 4 and can accommodate wind turbines up to 5MW. These platforms are among the most advanced floating substructure concepts currently being developed in Europe.

Progress update

The Design basis (MS#1) provided the concept developers with the information required to upscale their floating platform concepts to support a 10MW wind turbine in three reference locations (Golfe de Fos, Gulf of Maine and West of Barra), representing different met-ocean conditions, and to identify the load cases and the wind turbine models for the design.

Bilde 1

In the second technical milestone (Concepts designs ready), the concept developers used information from MS#1 to upscale their concepts to accommodate a 10MW wind turbine. In this ongoing upscaling/optimization process, radically different choices regarding structural design, mooring design, wind turbine controller and marine operations are required.

In parallel, the Design practice review (MS#6) an overview of current design practice, procedures, methodology, guidelines and standards with a gap analysis was carried out.

Evaluation methodology ready (MS#3)has produced a LIFES50+ Overall Evaluation tool named “Floating Offshore Wind Assessment Tool (FOWAT)” to qualify the four concepts designs under an economic, environmental, risk and technical perspective. Of note is that floating wind energy is still at the early stages of its development and the associated experience is scarce. Therefore, the criteria and weighting factors that are applied in the evaluation tool are the agreed best estimates of the partners involved in the project and the tool development.

Phase 1 will be completed at a workshop in Barcelona from 8-10 of March 2017, where the Phase 1 qualification performed (MS#4) will present the evaluation of the four innovative concept designs and disclose the results. The overall concept rankings will be based on the scoring results obtained by the Levelised Cost of Energy (LCOE), Life Cycle Assessment (LCA) and Risk evaluation determined by FOWAT.


Phase Two – Concept optimisation

Phase 2 of the project officially begins in April 2017, when the two selected concepts will undergo further studies in order to accommodate a 10MW wind turbine. The innovative concepts will be further developed, technically and economically, to reach a higher technology readiness level. Industrialisation, manufacturability and environmental impacts will also be considered with relevant guidelines/recommended practices produced.

Experimental results from scale model testing in both ocean basin and wind tunnels will be used to for further development and verification the technologies using numerical simulation tools. The ultimate goals are to facilitate innovation, reduce risk, and reduce the LCOE and the uncertainties associated with its estimation.

















  1. Substructure design for very large floating offshore wind turbines (10MW)
  2. Methodologies for design evaluation, including LCOE (Levelized Cost of Energy)

To realize these goals, we need:

  1. Multi-fidelity numerical tools in the context of qualifying and optimizing large substructures
  2. Experimental techniques specific to floating offshore wind turbines
  3. Concept industrialization, as an early focus in the design
  4. Uncertainty and risk assessment related to unprecedented large wind turbine substructures


–   Mature floating substructure design synchronized with the expected time-to-market of 10MW offshore wind turbine technology
–   Increased scientific and industrial knowledge on numerical and experimental design methodologies and procedures, also enabling more streamlined, KPI based developments
–   Ultimately, a considerable LCOE reduction for large floating offshore wind farms




There is a need for new innovative substructure concepts, including floating platforms, to reduce production, installation and O&M costs for water depths of more than 50m.


• Optimize and qualify to a Technology Readiness Level – TRL of 5, two innovative substructure designs for 10MW turbines

• Develop a streamlined and KPI (key performance indicator) based methodology for the evaluation and qualification process of floating substructures


– Floating wind turbines installed in water depths from 50m to 200m

– Offshore wind farms of large wind turbines (10MW) – identified to be the most effective way of reducing cost of energy in short term




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