Coal-fired Integrated Gasification Combined Cycle (IGCC) and Integrated coal Gasification Fuel-cell Combined cycle (IGFC) are being developed as high-efficiency electric power generation technology. However,the highest theoretical gross thermal efficiency of the conventional IGCC/IGFC is still below 52%. In order to obtain higher power generation efficiency, an advanced IGCC (A-IGCC) or advanced IGFC (A-IGFC) system making use of the exergy recuperation concept by recycling waste heat from gas turbine or fuel cells for steam gasification of coal and biomass was proposed in our laboratory. Corresponding to this system, a novel high-density triple-bed combined circulating fluidized bed (TBCFB) gasifier, composed of a downer pyrolyzer, a bubbling fluidized bed char gasifier, and a riser combustor, was proposed to replace traditional gasifiers such as the entrained flow bed gasifier. The new system is expected to more effectively utilize the waste heat from gas turbines or fuel cells and the heat produced by the combustion of the unreacted char in the riser combustor for pyrolysis and gasification of coal and biomass. In this short review, the advantages and future challenges in the development of high-density TBCFB gasifier are presented and discussed.