Comparative studies of advanced MHD topping power generation systems

Efficiencies of four different types of MHD topping combined systems were compared where the topping units were the MHD generator and a thermochemical coal converter. The bottoming system was either combined gas and steam turbine units, a steam injection-type gas turbine, a steam turbine unit or a steam turbine coupled with a biomass unit. We also considered an IGCC system with conventional gasification schematics as a reference case. We showed that the system combined with the steam turbine and biomass units exhibited the highest efficiency of over 60% with presumably attainable MHD unit efficiencies although it is workable only under sunlight and its power scale may be limited by the pond area of the biomass plant. The present results emphasize capabilities of an advanced power generation system with extremely low environmental impacts and high efficiencies among those of the so far proposed fossil fuel-fired power plants on the basis of the MHD and the state-of-the-art heat recovery technologies