Application of integrated wave-to-wire modelling for the preliminary design of oscillating water column systems for installations in moderate wave climates

Oscillating water column (OWC) devices are the technical solution more favourably considered for a significant future exploitation of the energy potential of sea waves. While theoretically quite simple, these systems are indeed rather complex in terms of correct tuning between the caisson and turbine. Recent studies showed that only a holistic approach, also including turbine control, is the way of effectively performing their precise design. To this end, the research presents the application of an analytical wave-to-wire model of an OWC device for the preliminary optimisation of these systems for a small installation in a moderate wave climate in the Mediterranean Sea. More specifically, scatter matrices were determined for imposing the wave states of a selected location positioned in Tuscany (Italy). Regarding previous similar studies, a novel joint optimisation of the caisson and controlled turbine is proposed for the specific site. Either monoplane isolated Wells turbines and axial impulse turbines were analysed. The operating curves, performance parameters, and attended annual energy harvesting were calculated, providing an interesting overview of the functioning of the system. The optimised devices with the Wells and impulse turbomachines convert 36.71 and 42.17 MWh/year operating with a global efficiency of 6.82% and 7.84%, respectively.