Development of a wave energy converter using a two chamber oscillating water column

This paper presents the development and system analysis of segmented oscillating water columns (OWC) for wave energy conversion based on the wave conditions around Taiwan. The OWC chambers are designed for a target site and the power converted by each component (i.e., the chambers, turbine and generator) in the power chain is analyzed so that the overall power output and efficiency can be calculated. The characteristic match between the turbine and the generator is also discussed. The developed OWC is side-mounted and this allows the waves to penetrate and continue propagating after transferring power to the chambers. The OWC consists of two adjacent chambers which are aligned in the direction of the wave propagation. Each chamber has one Savonius turbine on top to convert the chamber power into mechanical shaft power. The two turbines are connected in-line and the individual chambers transfer power to the turbines with a phase difference, so that the power output can be smoothed. A brushless permanent-magnet generator is used to convert the turbine output power into electricity. Experiments are conducted on a scaled-down model in a wave tank to evaluate the performance and the results verify the design. It is also found that the successive chamber should have a different design to the first one as it suffers slight wave attenuation.