ABSTRACT

This paper presents a parametric study on oscillating water column (OWC) wave energy converter (WEC). The OWC is being planned to be placed on a breakwater in isolated islands remote from the land. Both of numerical analysis and model experiment were utilized for deciding a proper conceptual design that covers the purpose. Various design parameters including configurations and dimensions were evaluated through the numerical analysis, which is based on a potential flow theory, and then several design concepts were selected as candidates. The model experiment using a 2D wave flume was performed to evaluate effects of design parameters and compare performances for the candidates. Based on overall results from the numerical analysis and the model experiment, a conceptual design of the OWC WEC applicable to a breakwater was selected.

INTRODUCTION

The oscillating water column (OWC), a kind of wave energy converters (WECs), utilizes motions of water column vertically oscillating in the chamber, which produces reciprocating air flow that operates a turbine connected from the chamber by a duct. The OWC WEC has easy maintenance and reliable durability due to its simplicity, so it has been demonstrated commonly in real sea for that reason (Falcao and Henriques, 2016). A first developed large-scale OWC system was Kaimei, installed at western coast of Japan. Eight OWC chambers with capacity of 125kW were equipped on the barge platform, and several turbines had been evaluated on Kaimei (Masuda and McCormick, 1986; Hotta et al., 1988). Another OWC with Wells turbine, capacity of 40kW was deployed into a breakwater located in Sakata port, Japan, in 1990. It was the first case that the OWC was merged into a breakwater, then some cost saving effects were shown (Masuda and McCormick, 1986). In the same year, bottom-fixed OWC with capacity of 125kW was installed at Trivandrum, India. Performance for various turbines including impulse type were evaluated (Mala et al., 2009). In Europe, Pico Plant which is constructed at Pico island, Portugal, with capacity of 400kW has been tested since 1999 (Falcao, 2000), and LIMPET OWC Plant which is deployed at Islay island, Scotland, with capacity of 500kW was evaluated during a real sea test (Heath et al., 2000). In Korea, construction of a bottom-fixed OWC with capacity of 500kW was completed in 2015, and then a real sea test is being prepared.

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