Feasibility Study of Steam Injection and Combined Cycle Technologies Based on Economic Analysis

Abstract

This study aims to evaluate the economic feasibility of Steam Injection Gas Turbine (SIGT) and Combined Cycle Power Plant (CCPP) technologies when applied to two Siemens SGT5-2000E gas turbine units. An integrated economic model was developed based on key financial performance indicators, including Capital Cost, Net Present Value (NPV), Payback Period (PBP), Annual Rate of Return (ARR), and Profitability Index (PI). In addition, the impact of variations in electricity selling prices and fuel prices on the economic performance of the studied systems was investigated. The results showed that the steam injection technology achieved the best economic performance compared with both the combined cycle and simple cycle configurations. The capital cost increased by only 4.1% relative to the base case, while the technology achieved the highest NPV of USD 1,845.71 million, the shortest payback period of 0.61 years, the highest ARR of 71.0%, and the highest PI of 5.97. In contrast, the combined cycle technology required a substantial increase in capital cost of 50%, which adversely affected its economic feasibility indicators despite the noticeable improvement in overall performance. Sensitivity analysis further revealed that increasing the electricity selling price from 0.055 to 0.08 USD/kWh improved all economic indicators for the three systems. However, steam injection consistently maintained the highest NPV, ARR, and PI values, in addition to the shortest payback period across all electricity price levels considered. Conversely, increasing the fuel price from 0.019 to 0.079 USD/kg reduced the economic performance of all systems; nevertheless, steam injection demonstrated the greatest resilience to fuel price fluctuations, maintaining superior investment returns and the best profitability and economic efficiency indicators. The findings confirm that steam injection technology represents the most economically viable option for upgrading SGT5-2000E gas turbine power plants, providing an optimal balance between investment cost and economic return while ensuring rapid capital recovery and greater resistance to variations in energy and fuel prices. These results provide valuable decision-support guidance for policymakers, planners, and energy-sector stakeholders in selecting appropriate technologies to enhance the economic performance of gas turbine power plants.