The study regards the issues of increasing the thermodynamic efficiency of a typical condensing thermal power plant using coal-water and organic coal-water fuels as the main source. The attention is paid to the use of the phase transition heat of the water vapor of the flue gas. We have shown that it is possible to increase the power plant efficiency by about 3.7% (gross) relative to the base value (in the case of using pulverized coal). We propose to use the flue-gas desulfurization technology for creating fuel slurries in which a liquid incombustible base will be replaced, for example, with aqueous solutions of Ca(OH)2. This will create a closed water cycle, improve the efficiency of Sox flue gas purification and improve the performance of scrubbers.