Energy, Exergy, and Exergoeconomic Analysis of a Combined Cycle Power Plant With Post-Combustion CO2 Capture: A Case Study in Northern Iran

Efficient energy use and new resource development are important due to increasing global energy demand from population growth. This study reports energy, exergy, and exergoeconomic analyses of a new F-class CCPP (combined cycle power plant) in Northern Iran. Moreover, the environmental aspects and global warming induced by the pollutant emissions of fossil-fueled power plants are discussed, analyzing the process of capturing CO2 from the exhaust gases. The case study CCPP's efficiencies of the first and second laws of thermodynamics were 54.97% and 51.69% using the developed model, respectively, representing relatively satisfactory performance relative to other similar power plants. However, it was found that the combustion chamber required modification as it had a dramatic exergy destruction rate of 85% and an exergy destruction cost of more than $4000 per hour. Moreover, the effects of ambient temperature and gas turbine input temperature as the major determinants in improving the exergetic performance of the cycle were assessed. It was found that a reduction in ambient temperature and a rise in the output temperature of the combustion chamber (gas turbine input temperature) would improve the overall performance of the system. Although this factor leads to an optimal total plant cost at a temperature close to 1420 K, the exergoeconomic evaluation of the system components identified the combustion chamber as the primary candidate for improvement. Investing in better design of the combustion chamber was recommended to reduce exergy destruction costs. Finally, the CO2 capture rate from the stack exhaust gas was found to be 89.77%, with a capture unit energy penalty of 0.963, which is acceptable.