Optimization of Low Head Axial-Flow Turbines for an Overtopping BReakwater for Energy Conversion: A Case Study

Abstract

Overtopping-type wave power conversion devices represent one of the most promising technology to combine reliability and competitively priced electricity supplies from waves. While satisfactory hydraulic and structural performance have been achieved, the selection of the hydraulic turbines and their regulation is a complex process due to the very low head and a variable flow rate in the overtopping breakwater set-ups. Based on the experience acquired on the first Overtopping BReakwater for Energy Conversion (OBREC) prototype, operating since 2016, an activity has been carried out to select the most appropriate turbine dimension and control strategy for such applications. An example of this multivariable approach is provided and illustrated through a case study in the San Antonio Port, along the central coast of Chile. In this site the deployment of a breakwater equipped with OBREC modules is specifically investigated. Axial-flow turbines of different runner diameter are compared, proposing the optimal ramp height and turbine control strategy for maximizing system energy production. The energy production ranges from 20.5 MWh/y for the smallest runner diameter to a maximum of 34.8 MWh/y for the largest runner diameter.

Numerical Analysis of an Overtopping Wave Energy Converter Subjected to the Incidence of Irregular and Regular Waves from Realistic Sea States

“…Figures [16][17][18] show the variation of water volume (V) accumulated in the reservoir of the overtopping device over time due to the incidence of the representative regular waves and realistic irregular waves, respectively, for RG, SVP, and TV. It is possible to observe that for the cases numerically simulated with the representative regular waves, a greater volume of water was accumulated in the reservoir when compared to the cases with the realistic irregular waves, a trend that occurs in all analyzed locations.…”

“…More recently, Martins et al [13], also applying the JONSWAP spectrum, developed a numerical study on an overtopping device with one and two ramps incorporated into a real breakwater, performing a geometric evaluation through the Constructal Design method. It should be highlighted that one can find several other studies addressing the overtopping devices and OBRECs with different approaches and goals, such as the studies by Liu et al [14], Barbosa et al [15], Contestabile et al [16], and Mariani et al [17].…”

An Integrated Approach to Assessing the Wave Potential for the Energy Supply of Ports: A Case Study

“…Full-scale examples of WEC-breakwater integration are the OWCs of ports of Mutriku (Spain) [28] and Civitavecchia (Italy) [29], the overtopping device OBREC in the port of Naples (Italy) [30] and the Eco Wave Power hinged arm point absorber in Gibraltar [31]. In addition, extensive research has dealt with WEC-breakwater integration in different ports worldwide, addressing in detail relevant issues such as hydrodynamic and hydraulic performance enhancement of OWCs [32,33] and OTDs [34,35], respectively; PTO optimisation [36][37][38], wave loading distribution and structural integrity [39][40][41], economic and life-cycle environmental impact assessment [42,43] and hybridisation of OWC and OTD concepts [26,44].…”