In this paper, effect of working medium property including density and electrical conductivity on performance of heaving float wave energy converter/conversion (WEC) with liquid metal magnetohydrodynamic (LMMHD) generator was investigated. The results reveal that low density of working medium is required to reduce the damping of PTO system. With the increase of electrical conductivity, damping force of PTO system increases remarkly and there is a maximum value for the power output. The working medium should also be with the characteristics of low melting point, low viscosity and non-toxic.
Ocean wave energy may become an unquestionable alternative to actual clean energy sources in the near future. The global wave energy (including that on the open ocean) is in the order of 1013W (Falnes, 2007), a quantity that is comparable with the world's present power consumption. China also has abundant wave energy resource with a theoretical value of 1.284×1011W (Wang, 2009), therefore, development and utilization of wave energy converter/conversion (WEC) become the world's hotspot.
Rotating generators are used traditionally for wave energy conversion, which require an intermediate system to convert the slow linear/rotation motion of the wave capturing system into a high speed rotating one. It is complex, bulky, low efficient and expensive. A new way to generate electricity directly from ocean wave motion has been investigated (Peng, 2008, Liu, 2015, Liu, 2016, Zhang, 2016) in Institute of Electrical Engineering, Chinese Academy of Sciences (IEECAS), China. It makes use of a reciprocating LMMHD generator, whose speed-torque characteristics match the mechanical impedance of wave energy excellently, so there are no complex intermediate systems in LMMHD-WEC. It is considered to be high efficient and compact with a very high power density, and it is expected to be one of the best ways to convert wave energy into electricity directly.
In this paper, effect of working medium property including density and electrical conductivity on performance of heaving float wave energy converter with LMMHD generator was investigated.