This paper will develop a variant of the methodology introduced in a paper previously published in this journal, which was used to estimate the atmospheric pollution by the flue gases of thermopower plants (TPPs), It will take into consideration two virtual fuels, treated as limiting cases, in order to compare them with other real fuels. We will draw conclusions regarding the character of fuels used and optimal ways to use the energy of the fuels burned in TPPs from the ecological impact point of view and also of the efficiency of the electrical and/or thermal energy produced.