Comparative Study of Gas Turbine Performance Under Varying Fuel Gas Compositions in Edo State

Gas turbines are widely deployed across Nigeria's power generation and industrial compression sectors, yet their performance is sensitive to variations in fuel gas composition. This study conducts a comparative analysis of gas turbine operational performance under varying fuel gas compositions at selected generation facilities in Edo State, including the Ovia Power Plant and industrial co-generation units at manufacturing facilities in Benin City. The research employs an experimental case study design, collecting fuel gas chromatography data, turbine operational logs, and performance parameter records including thermal efficiency, heat rate, turbine inlet temperature, and exhaust emissions. The study investigates the effect of elevated hydrogen sulphide content, fluctuating calorific value, and varying inert gas concentration on turbine combustion stability and thermal efficiency. It further examines the adequacy of fuel gas conditioning equipment at the studied facilities in managing these compositional challenges. Findings indicate that turbines operating on lean gas with calorific values below 900 BTU/scf experience measurable efficiency penalties and elevated NOx emissions. The study recommends real-time fuel gas composition monitoring, installation of Wobbe Index control systems, and alignment of turbine fuel specifications with ISO 13691 guidelines for natural gas fuelling of turbines. These insights are relevant to power operators, turbine maintenance engineers, and gas suppliers in Edo State and the broader South South region. Keywords: gas turbine, fuel composition, thermal efficiency, Wobbe Index, Edo State.