STRUCTeam, the independent composite engineering consultancy based in Cowes, UK, has supported the world’s leading wind turbine and blade manufacturers for over a decade. It is now extending its strategic insights to the application of composites in wave power with renewables company Ocean Energy and technical partners 3A Composites Core Materials and Sicomin.

Ocean Energy approached the STRUCTeam for support with an EU-funded Horizon European Framework Programme with the objective of securing a sustainable and competitive energy supply through renewable applications.

This centres around the development of an oscillating water column (OWC), named the ‘OE12 Buoy’. The wave energy convertor is designed to glide on the ocean surface and extract power from the motion of the water which is then converted into electricity.

As the project has evolved, the desire to achieve weight savings in the steel structure’s design has become a key objective. Technical partners 3A Composites Core Materials and Sicomin have been invited by STRUCTeam to collaborate with the supply of recycled core materials and bio-based epoxy resins to enable the light weighting process.

Weight savings

The current OE 12 Buoy prototype is manufactured from steel and does not incorporate any composite materials. The device weighs twenty-eight tons and measures twelve metres by six metres. STRUCTeam estimates a 30-50% reduction in weight could be possible through careful engineering and materials selection.

The benefits around weight reduction are clear and convincing. A lighter structure allows for simplified transportation and installation, and in turn, lower levelised cost of energy (LCOE). The environmental benefits of composites are also motivating factors, such as the potential reduction in C02 emissions, improved materials circularity and durability.

Each of the technical partners places a strong emphasis on the circularity of materials in the projects they undertake.

“After being contacted by Ocean Energy, our choice to bring these companies together was very deliberate,” said Julien Sellier, STRUCTeam managing director. “They possess extensive knowledge in the development and adoption of lightweight materials for large structures that transfer perfectly to this project.”

The partners have proposed technologies and design solutions to successfully replace traditional material choices in the buoy structure.

Epoxy formulator Sicomin has developed a range of environmentally-enhanced green epoxy systems derived from natural origins. The Greenpoxy range incorporates InfuGreen 810, a two-component product specially formulated for resin transfer processes such as injection and infusion.

3A has developed Airex T92 and proposed it is used throughout the composite buoy. A closed-cell, thermoplastic and recyclable polymer foam with exceptionally good mechanical properties, it has an extraordinary resistance to fatigue, is chemically stable, UV resistant and has negligible water absorption, making it ideal for marine applications. The core material is suitable for a wide variety of lightweight sandwich structures that are subject to static and dynamic loads.

All parties anticipate a successful funding bid and look forward to developing the preliminary specifications of the composite structure. STRUCTeam will then initiate a pre-study analysis, conduct a first assessment and finalise design requirements.

 “Our wave devices have virtually no environmental impact so to extend their sustainability credentials in manufacture, installation and service is a crucial factor,” saids Sean Barrett, senior project engineer at Ocean Energy. “STRUCTeam and its partners have guided us through the initial design phase and made valuable recommendations.”

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