The purpose of this study is to develop a new wave energy conversion system using a floating breakwater. A gear box and dynamos are employed as the drive system and generator, respectively. The performance of the proposed system is demonstrated by conducting hydraulic model experiments. Experimental results show that high wave energy conversion efficiency up to nearly 11% can be achieved with the wave period of 1.6 s. Moreover, a good wave controlling is confirmed by the average energy dissipation rate of more than 0.6 in tests of both water depths. Moreover, the effects of wave steepness and number of dynamos on behavior of floating body, wave energy dissipation and power generation are also investigated.
Wave energy is a highly promising renewable energy source due to its highest energy density compared with other renewable energy resources (Clement et al., 2002). Another advantage of wave energy plants is the numerous potential sites. Namely, wave energy palnts can be located near economically developed area, on the coastline, which is very important for the island countries such as Japan. The total wave energy available around Japan is estimated as 35 Gigawatt (GW) (Takahashi, 2008) which is more than 1/4 of the average electric power generation of Japan in 2007. Therefore, the utilization of wave energy is expected to provide a significant proportion of future energy requirements without adding to pollution and global warming. Numbers of wave energy converters have been developed and tested in recent years (Kofoed et al., 2006; Henderson, 2006). Falcão (2010) reviewed these technologies and classified them into three main types: oscillating water column (OWC) systems, oscillating body systems and overtopping converters. However, the cost of extracting energy from ocean's wave with current technologies is relatively expensive and thus limits the development of wave energy industry.