Experiences in Pneumatic Wave Energy Conversion in Japan

Several prototype and model studies of pneumatic wave energy conversion systems are discussed. These include those of the floating platform KAIMEI, the fixed system at Sanze and the new system called the Backward Bent Duct Buoy (BBDB). Although the overall conversion efficiency of the KAIMEI system in converting wave energy to pneumatic energy was poor, the subsequent conversion of the pneumatic energy to electrical energy by the impulse turbines the McCormick turbine and the Wells turbine was excellent. The overall performance of the fixed system at Sanze was far superior to that of the KAIMEI since there is no phase cancellation of the relative motions of the internal wave and the capture chamber. The fixed system appears to be most economical in supplying power to near mainland islands. The floating system can be dramatically improved by using the BBDB concept.