Assessment of Floating Wind Turbine Foundations for North Sea Conditions

Concrete foundations could be the best option for developers of floating offshore wind farms in the North Sea, a new report says.

The material’s durability, low maintenance requirements, lower capital expenditure (CAPEX) and suitability for UK construction could provide a competitive alternative to steel designs, according to the study by consultancy OpenWater Renewables Ltd.

More than 100 substructure designs and materials are available to wind farm developers, including steel, concrete and hybrid, which makes choosing the best option a significant challenge.

The UK Technology Leadership Board commissioned OpenWater Renewables to produce a study identifying the concepts best suited to the North Sea, boosting developers’ chances of success.

OpenWater Renewables used its proprietary ranking software to shortlist 15 concepts ranging from Technology Readiness Level (TRL) 5 to TRL 7, comprising three barges, 11 semi-submersibles and one tension leg platform.

Whilst private wind farm developers and others have performed similar analyses, their results are generally not available in the public domain.

The work considered a fictional North Sea wind farm and key factors relevant to floating wind turbine foundations which impact end users’ selections for their projects.

Critical factors included installation, CAPEX and operating expenditure, financial strength, and project track record. Technical maturity was also a key factor in assessing the concepts. 

For North Sea projects, ease of installation and repair were seen as key differentiators due to the short weather windows in which critical work has to be done. 

All of the shortlisted concepts are suitable for fabrication in the UK, once suitable port infrastructure is available

The report also highlights promising but less mature FOW concepts that are not yet at the prototype/demonstrator stage which require accelerated development to be ready for deployment by 2030-2035.

The report makes three main recommendations to further support developers with the selection process:

• Develop an industry standard definition of TRL for FOW projects

• Accelerate the development of the shortlisted concepts currently qualified as TRL 5.

• Study the leading UK-based concepts to examine their ranking and determine the scope and potential timeline to optimise their development paths for selection for North Sea projects.