To correctly judge the effectiveness of cogeneration, the meaning of cogeneration effectiveness must be clearly understood, and proper methods of evaluating it must be used. Overall cycle thermal efficiency or fuel utilization factor and cogeneration cycle electrical efficiency cannot be used in most cases to evaluate the effectiveness of cogeneration. Electrical and thermal energy generated by the cogeneration plant are not of equal quality and, therefore, cannot be treated equally. The generation of electricity as a by-product of thermal energy production in the cogeneration schemes is the key factor affecting the fuel effectiveness of cogeneration. Therefore, evaluation methods that are based on the ratio of electrical to thermal energy production are most suitable for evaluating the effectiveness of cogeneration. A higher power-to-heat ratio normally results in higher fuel savings and, therefore, is more economically attractive.