A dual-functional wave-power plant for wave-energy extraction and shore protection: A wave-flume study

The fundamental roadblock toward commercial-scale wave power operations is cost. The main objective of this work was to address the cost challenge facing wave energy commercialization through cost-sharing with pile breakwaters to be built for shore protection. This was achieved in this study through a dual-functional wave-power plant for generation of wave-power electricity and protection against coastal erosion for sustainable coastal development. The dual-functional wave-power plant was formed by integrating oscillating-water-column (OWC) devices into a pile breakwater, with each pile being an OWC-pile equipped with a power take-off device. The power extraction efficiency and hydrodynamic characteristics of the dual-functional wave-power plant were measured in a wave flume under various wave conditions. An orifice was used at the top of the pneumatic chamber of each OWC-pile to simulate the power take-off device. To evaluate the performance of the power plant in wave power extraction and shore protection, the surface elevation and pressure inside the OWC chamber, as well as the scattered waves, were measured. It was found that comparing to a standalone OWC-pile device with an identical design and geometric characteristics, an OWC-pile in the dual-functional wave-power plant could achieve significantly larger power-extraction efficiency. Comparing to a pile breakwater with the same dimensions, the wave transmission and reflection of the dual-functional wave-power plant were both weaker, especially the wave reflection, which is beneficial for structure safety and shore protection. Based on the Froude's law of similarity and an estimation of the effect of air compressibility at full scale, an evaluation of the performance of a dual-functional wave-power plant at full scale was also provided. The findings of this work promote close collaboration between wave-energy utilization community and the shore-protection community for commercial-scale deployment of wave energy converters and contribute to making wave energy economically competitive.