NetBuoy integrates two enabling technologies for cost competitive wave energy – impermeable membranes to manufacture buoyant modules and fibre rope nets to encapsulate the buoyant modules. The net applies distributed restraint loads and agglomerates them back to structural ‘hard’ point(s). This is essential in enabling the use of membrane buoyant modules as they cannot be restrained otherwise.
This combination of elements significantly reduces prime mover mass when compared to the use of steel; the density of the materials are around one-seventh that of steel. The materials are much more compliant. This compliance, with strain at break of around 15% for the membrane, means it can locally deform under extreme loading whereas a steel structure must carry excess mass (and therefore cost) to provide the required rigidity to avoid plastic deformation.
The inflatable module affords significant advantages in all phases of the lifecycle. A deflated buoyant pod can be cheaply transported in a shipping container. CAPEX and LCOE calculations at Stage 2 show very encouraging potential for step-change cost reductions. The buoyant pods can be manufactured globally using existing supply chains.
The Stage 3 project will install NetBuoy(s) in the ocean environment to assess the effect of long-term exposure to seawater, environmental loading, biofouling and UV and ozone. This will increase the TRL to 7. Tank testing will be performed that will demonstrate the application to WEC forms other than point absorbers to increase the technical and commercial readiness in this respect.
The long-term vision for the proposed solution is integration into wave energy converters, utilising the NetBuoy to provide the prime mover water plane, swept volume and buoyancy requirements.