In this work, the heat balance was calculated for a plant that produces 900 MW of electricity and uses steam of 300 bar pressure and temperature of 600 °C with one intermediate superheater and 9 regenerative feed water heaters. In the introductory part of the work, thermal power plants are described with an emphasis on supercritical plants and their parameters of process operation. Then, the amounts of steam extraction required for regenerative heating of feed water in four high-pressure, four low-pressure and one open regenerative feed water heater is calculated. After that, the total amount of required steam that the steam generator must produce is calculated as well as the required amount of natural gas as fuel used by the steam generator is determined. The efficiency of this process in ideal and realistic conditions was calculated. The composition of flue gases was also calculated and a system for separating and removing carbon dioxide was proposed. The process is also shown in a mathematical model using the Ebsilon professional software package, and a comparison of subcritical and supercritical plant parameters is provided with that model, and how the change in parameters affects plant utilization and emissions is shown. There is a clearly visible advantage of supercritical plants in terms of efficiency and lower emissions, and that makes clear the aspiration and the direction in design of technology advancements of such supercritical power plants. In the second part of the work, an energy and exergy analysis of parts of the plant and the entire plant was carried out, and the energy and exergy losses and efficiencies occurring in individual parts were presented. It is shown how the change of environmental parameters, more precisely the temperature of the environment, affects the exergetic analysis of losses and efficiencies. This is a clear indication that this type of analysis can be used for a more precise analysis of the plant, its losses, and efficiencies and for clearer view on the improvements that can be implemented.