A new way to generate electric power directly from ocean wave motion is presented in the paper. It makes use of the liquid metal magnetohydrodynamic generator, and provides an excellent match to the mechanical impedance of an ocean wave, which is impossible to supply in other wave power systems. Therefore, the system is highly efficient and can be a very compact device with very high power density, and it is expected to be one of the best ways to convert ocean wave directly into electricity. Performance analysis, such as current and voltage, power output and efficiency, has been carried out when the wave has amplitude of 1 m and period of 6 s. The results show that the electric current and voltage periodically vary with the wave oscillation, the maximum output power of 3.35 kW and conversion efficiency of 68% can be obtained at load factor of 0.85 and 0.6 respectively while the magnetic field is 0.5 T.
Ocean wave energy is a renewable energy source with a huge potential, harnessing the immense power of ocean waves to do useful work has been a dream of mankind for millennia. In recent decades, this goal has become more specific, i.e., conversion of ocean wave motion into electricity via practical and cost-effective means. There are various ways to convert ocean wave energy into electric energy, such as oscillating water column (OWC) wave energy converter (Bonke, 1985), overtopping wave energy converter (www.oceanpd.com), Pelamis (Yemm and Henderson, 2000; Pizer and Retzler, 2000) and etc. Another way worthy of notice is AWS that can directly converts wave motion into electricity (Rademakers and Schie, 1998; Polinder and Mecrow, 2005). Magnetohydrodynamic (MHD) power technology supplies a new method to convert the thermal energy directly into electrical power. Principle of MHD power generation is shown in Fig.1.