Wave energy developer Carnegie Wave Energy Limited announced the completion of the preliminary design for the first CETO grid-connected project.
Following the successful in-ocean trial of the CETO 3 commercial scale unit earlier this year, Carnegie’s technical team has analysed a huge quantity of data allowing further validation and development of the CETO design utilising Carnegie’s virtual modelling capabilities. This analysis and design work has focused on the full CETO system including the CETO unit design and foundations, pipeline and onshore power generation facility.
It concludes that the first grid-connected CETO demonstration project should be between 1 and 5MW peak capacity with an optimum of approximately 2MW peak.
Carnegie’s CEO and Managing Director, Dr Michael Ottaviano said,
“The completion of the preliminary design for the 2MW grid-connected project represents a major step forward in CETO’s technology maturity. The next phase of the process is for Carnegie to confirm a final location for this demonstration project. This will be Carnegie’s first power project and will deliver our first project-based revenues through the sale of the electricity generated.”
Selection of the location of the project site will allow the completion of detailed project design ahead of project construction.
Unit Optimisation
The CETO 3 analysis has provided the basis to optimise the Buoyant Actuator’s hydrodynamic properties to increase power output through more efficient energy capture and conversion.
Through optimisation of the Buoyant Actuator geometry, the preliminary design offers a two-fold increase in power production from the CETO 3 unit, with only relatively minor modifications, thereby delivering a significant reduction in the cost of generation.
Power Generation Facility
The onshore power generation facility contains the hydro-electric equipment including the Pelton Wheel Turbine, electrical switchgear and the instrumentation and control system. The preliminary design ensures high availability through redundant systems, in particular the turbine and generator.
Significant effort has been put toward designing, modelling and simulating the control algorithm that regulates the pressures in the pipelines. The physical footprint of the onshore facility has also been minimised to allow flexibility in siting and to ensure minimal visual impact.
Foundation
The design of the pile foundation has been largely focussed on the integration of a quick-connect system to allow CETO units to be installed and operational within a 24 hour window. This is in contrast to the 7 days required for the CETO 3 installation. The design incorporates both the structural and hydraulic connections using proven technology originating from offshore oil and gas applications. The new installation method, devised following learnings from the CETO 3 deployment, also tailors the diving and vessel requirements to those that are locally available in all prospective demonstration sites reducing installation cost and risk.
Pipeline to Shore
A small bore (200mm nominal diameter) pipeline carries the hydraulic energy back to shore from the CETO unit array and has been a focus of hydraulic modelling and optimisation work. Transient effects have been managed through careful sizing of surge vessels allowing a smaller pipeline than would have otherwise been possible. At the outlet of the turbine a similar pipeline returns the water-based working fluid back to the array for re-pressurisation. Optic fibre communications cables piggy-back the pipeline connecting the CETO unit instrumentation to the control system onshore.
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Offshore WIND staff, December 08, 2011; Image: carnegiewave