Economic and environmental impacts of selected gas turbine power plants in Nigeria

In this study, assessment of economic and environmental impacts of selected gas turbines in Nigeria is carried out using the first and second laws of thermodynamics (exergy) concept. The results of the study showed that the combustion chamber is the most exergy destructive component compared to other cycle components. The percentage of exergy destruction in combustion chamber varies between 86.05% and 94.6%. By increasing the gas turbine inlet temperature (GTIT), the exergy destruction of this component can be reduced. Also, from exergy improvement potential point of view, combustion chamber has the highest exergy improvement potential which range from 30.21 to 88.86 MW. Thermo-economic analysis shows that the cost of exergy destruction is high in the combustion chamber, and an increase in the GTIT effectively decreases this cost. Thermo-environomic analysis shows that the CO2 emissions varied between 100.18 to 408.78 kgCO2/MWh while cost rate of environmental impact varied from 40.18 $/h (N6, 388.62/h) to 276.97 $/h (N44, 038. 23/h). The results further show that CO2 emissions and cost of environmental impact decrease with increasing GTIT. This study has provided a suitable methodology for relatively quick identification of the key items requiring performance improvement in a gas turbine power plant.