Since 2005, a new way to generate electric power directly from oscillatory ocean wave action has been investigated in Institute of Electrical Engineering, Chinese Academy of Sciences. It makes use of a liquid metal magnetohydrodynamic generator to convert mechanical power from ocean waves into usable electric power. A demonstration facility has been built to investigate a LMMHD wave energy conversion, and performance experiment for LMMHD generator has been carried out. In the experiments, mercury was selected as the working fluid, and the hydraulic system generates a reciprocating motion to simulate a wave capture system. A LMMHD generator with a permanent magnet was designed and manufactured. The maximum output power of 160W was generated in the experiment. Details description of the experimental facility, results and discussion are presented in the paper.
Wave energy is one of the most promising forms of ocean renewable sources because of its high energy density. Numerous attempts and researches have been continuing to extract power from ocean waves. There are various ways to convert ocean wave energy into electric energy, such as oscillating water column (OWC) wave energy converter, oscillating bodies, overtopping wave energy converter and etc.(António F. de O. Falcão, 2010) Liquid metal Megnetohydrodynamic wave energy conversion (LMMHD WEC) is a new way to generate electric power from ocean wave motion directly. LMMHD WEC makes use of a LMMHD generator instead of a conventional rotating electric generator to convert mechanical power supplied by very strong, but slow moving forces from ocean waves into usable electric power. LMMHD output (very high current, low voltage) can be converted to more practical levels via efficient electronic switches and compact transformers. The LMMHD power take off system improves efficiency, mobility, simplicity, and reliability of ocean wave energy conversion systems.