Energetic and exergoeconomic evaluation of a stig cycle and cooled inlet air gas turbine powered by mixtures of natural gas and H2 in tropical climates

Using pure hydrogen (H₂) or mixtures of H₂ and natural gas in gas-fired power plants represents a viable route to decarbonize electric power generation. This study models a system designed to cool the air at the compressor inlet to 8.8 °C, achieve a flue gas oxygen percentage of 11.46 %, and produce 44.4 MW with a fuel mix ranging from 0 to 100 % H₂ operating in tropical climates, where temperatures exceed 30 °C and relative humidity exceeds 80 %. The analysis is based on energy, exergy, and exergoeconomic balance to obtain performance indicators that characterize plant operations. The results show that with 100 % H₂, the PCI increases by 144 % compared to 100 % natural gas. Furthermore, the energy analysis indicates that for every 10 % volume increase in the H₂ fuel mix, the CO₂ concentration decreased by 34 kg/m³, the NOx concentration increased by 1 kg/m³, the dew point temperature increased by 0.5 °C, the energy efficiency improved by 4.5 percentage points, the heat rate decreased by 7 %, and the specific fuel consumption decreased by 8.5 %. Furthermore, the total exergy destruction increased by 14.83 %, and the total exergy efficiency decreased by 2.7 percentage points. The exergoeconomic analysis shows that the specific cost of electric energy per GJ decreases by 10 % for H₂ contents higher than 80 % by volume. This work demonstrates that generating energy from gas turbine power plants with lower CO₂ equivalent emissions is possible. On the other hand, the effects of moisture content in exhaust gases and NO_X are known due to the greater presence of H₂ and higher temperature combustion.