The textbook describes the basics of thermodynamics of high-temperature gas and plasma, including the features of the state of dissociated gas and thermodynamic analysis of plasma as the working medium of some stationary power units. Methods for analyzing the efficiency of energy systems are considered, including the method of comparing thermal cycles and the exergetic method of analysis. Cycles of heat-power gas plants are described: cycles of compressors, piston engines, gas turbine plants. Separate topics include material on the cycles of steam power plants, the cycle of machine-free energy conversion and the cycle of refrigeration plants.