Experimental Assessment of a Roll-Based Wave Energy Converter

Most of the commercially viable prototypes of wave energy converters are designed for high-latitude locations with large wave heights. Typically, these prototypes require some stiffness and/or inertia tuning mechanism to optimize their power output by matching the system’s natural frequency to that of the local dominant wave. Today, most WEC concepts are surge- or heave-based. Recently, an innovative concept was proposed to generate energy from long-period waves by tuning the roll natural period of a 1200-tons barge using a passive tuning mechanism. This barge has a natural period of 13 seconds and could generate 178 kW of mechanical power when operating in 1.5 m beam waves in the Pacific Ocean. This work provides experimental evidence of the hydrodynamic roll response to incoming waves using a 1:40 model. Data for free decay test and roll response amplitude for different configurations are presented. One of the configurations was able to harness about 345 milliwatts from a wave having a height of 1.2 cm and period of 1.25 seconds with a 55% efficiency. The proposed WEC concept could have an application in tropical regions where wave heights are relatively small, and wave periods are long.