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

Abstract

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 NOX are known due to the greater presence of H2 and higher temperature combustion.

Keywords

• Hydrogen
• Natural gas
• Gas turbine
• Advanced exergy analysis