US company to use TTI’s NetBuoy concept for wave energy device

California-based wave energy technology developer Centipod has teamed up with TTI Marine Renewables, a Scottish subsidiary of Tension Technology International (TTI), on the development of its wave energy device.

Centipod, through its parent company Dehlsen Associates, has been awarded $1.8 million by the US Department of Energy’s (DOE) Water Power Technologies Office (WPTO) to complete the design of its C1P6 WEC where TTI’s NetBuoy concept will be used as the prime mover sub-system.

The C1P6 design will be put through technology qualification, beginning the certification process that will allow for a continuation into the fabrication, deployment, and prototype testing stages beyond the end of the award period in the first quarter of 2024.

The C1P6 wave energy conversion system will integrate TTI’s lightweight NetBuoy prime mover with Centipod’s high-performance power take-off (PTO) – a linear direct drive system known as Luma – to achieve highly efficient wave power conversion.

According to developers, the integration of the NetBuoy technology can substantially reduce the cost of construction and installation of wave energy converters.

The C1P6 WEC is targeting small utility-scale wave farms, micro-grids, and off-grid blue economy applications.

Alan McCall, managing director of Centipod, said: “NetBuoy has numerous advantages as a prime mover within our wave energy converter system, the primary benefits being low mass, increased durability, and corrosion reduction.

“Low mass is particularly beneficial to cost of energy across a broad range of categories. There are obvious impacts such as lowering initial capital expense, but NetBuoy also benefits performance since the low mass means less impact on system dynamics from the prime mover’s inertia, allowing for greater overall control authority.”

NetBuoy focusses on two strands on the path towards cost-competitive wave energy. Firstly, impermeable fabrics to provide compliant and load shedding, peak-load resistant, buoyant modules.

Secondly, fiber rope ‘load nets’ that encapsulate the buoyant modules, applying distributed restraint loads and agglomerating the distributed load back to structural points to connect to the other parts of the wave energy conversion system, such as PTO.

TTI’s NetBuoy concept was developed through Wave Energy Scotland’s (WES) precommercial procurement (PCP) program ‘Structural Materials and Manufacturing Processes’, the aim of which was to develop, demonstrate and qualify new materials and manufacturing processes that would reduce the levelized cost of energy for wave energy systems.

Ben Yeats, director of TTI Marine Renewables, said: “The WES funded program has propelled the NetBuoy concept along the technical and commercial readiness path and has been instrumental in advancing the technology in readiness for this exciting transatlantic collaboration.”

Successful completion of stage three of the program saw NetBuoy accomplish six months of sea trials in the Cromarty Firth, proving the technology’s resilience to prolonged exposure to sea conditions, environmental loading, biofouling and UV and ozone.

Ruairi Maciver, project manager for WES, added: “It is exciting to the see TTI continue to exploit the NetBuoy technology developed through WES’ program. Integration into a fully functional wave energy converter system was the logical next step and the collaboration with Centipod provides the opportunity to prove the ability of NetBuoy to reduce the cost of wave energy.”

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