Progress work of wave power generation was thriving in this 15 years in Japan. There were several different types including shore filed type and floating type. Casson fixed OWC in Sakata harbor will be a highlight of wave power study but this report introduces floating type OWC mainly including improvement of conversion efficiency double rotor Wells turbine electric generator. Power cost by new wave power device is calculated, it is estimated 5.6 cent/Kwh in Hawaiian sea.
Wave is one kind of natural energy it is produced by wind blowing on sea, and it is distributed on all over the sea surface which is 2/3 of the earth. I studied OWC mainly it is consists of air chamber, air turbine and generator. Wave power has strong force, but it is slow. Air chamber converts wave power to air power and turbine can produce high rotation speed to generate electricity. Kaimei test was a representative wave power generator test. It is a ship-shaped "attenuator", 80m in length, 12m in breadth and 5.5m in height, and displaces approximately 820 tons. There are 13 chambers on the hull and 4 buoyancy rooms. Each chamber has 50 square meters and 4 kinds turbine generator are tested, two were impulse turbines with valves the others were Wells and McCormick turbine of valveless type. Kaimei was tested 3 years on sea, mooring of slack chaine line and cable from Kaimei to shore Grid Line operated well through rough winter waves over 3 years (cable is still used after 10 years). It was concluded that a floating-type wave power device is feasible when conversion efficiency is improved.
Shore fixing IS one effective method to get reaction force against wave.