Energy production and effect of ecological efficiency on the electricity production cost of a combined cycle without/with supplementary fuel burning

The present article a natural gas combined cycle thermoelectric power plant, without/with supplementary fuel burning (SFB), was evaluated through an energetic, exergetic, environmental and economic analysis. The objective of this research is to show that the lower energy production related to the system without SFB is compensated by the higher environmental efficiency. The evaluations were carried out to determine the global efficiency and the energy benefits/losses from the different equipment. The environmental analysis determined all emissions, pollution indicator (Πg), and ecological efficiency (ε) considering the international air quality standards. Finally, the economic analysis determined the expected annual benefit due to the pay-back and the electricity production cost (PCEE), incorporating the effects of the environmental impacts. When developing the present study, the system without/with SFB evidenced a global efficiency of 50.81 % vs 47.39 %, respectively. In addition, the system without SFB showed better results of exergetic efficiency and irreversibility, its Πg and ε were 0.056 kg/MJ and 93.2 %. While its total emissions were 16 % lower. The economic analysis verified the annual benefit due to the pay-back for an annual interest rate of 4 %, 8 % and 12 %, and the PCEE showed an increase between 10 % and 12 % in the case with SFB.