This article discusses the method of thermal and exergetic analysis of cogeneration energy sources on the example of the gas turbine unit LM6000PF (GTU-CHPP "Vostochnaya"). The purpose of the exergetic analysis is to determine the most advantageous method for evaluating the performance of equipment from the point of view of thermodynamic efficiency. The comparison of GTU efficiency values obtained by calculation using the methods of thermal and exergetic analysis is performed. A special feature of the exergetic analysis is the use of an additional indicator in addition to energy – exergy. During the exergy analysis assesses the efficiency of use of energy to burn in the combustion chamber of the gas turbine fuel and working gas cycle for production of electric and thermal energy by comparison is actually a perfect work with the exergy of the process.