The Cost of Flexibility: Life-Cycle Assessment and Mitigation Pathways for LNG-Dependent Grids

Power systems with rising shares of variable renewable energy require dispatchable flexibility, but the economic sustainability of gas-fired generation is increasingly shaped by LNG exposure, fuel-price volatility, declining utilization, and incomplete remuneration for system services. This study develops an integrated life-cycle cost assessment and prediction framework that combines the operating period method, a multi-source natural-gas procurement price model, technical corrections for actual operating conditions, single-factor sensitivity analysis, and binary quadratic regression. Guangdong, China, is used as an empirical case because it combines concentrated electricity demand, a heterogeneous gas turbine fleet, and substantial dependence on externally supplied and imported gas. Across natural-gas prices of 2.0–3.5 yuan Nm−3 and annual utilization of 1000–4000 h, tax-inclusive levelized generation costs range from 0.4513 to 0.9246 yuan kWh−1 for 9H units, 0.4969–1.0349 yuan kWh−1 for 9F units, 0.5668–1.2019 yuan kWh−1 for 9E units, and 0.6114–1.4363 yuan kWh−1 for 6F units. Natural-gas price and gas-consumption rate are the dominant cost drivers, with sensitivity coefficients of 0.68–0.81, while costs rise sharply when annual utilization falls below 2000 h. The regression models achieve R2 values above 0.993 and enable rapid cost estimation under changing market conditions. The estimated costs are plant-level financial generation costs, not a complete measure of system-level flexibility value; likewise, the regression equations are bounded surrogate representations of internally calculated cost surfaces rather than independent forecasts of observed market outcomes. The results support coordinated mitigation pathways involving fuel procurement, gas-electricity market alignment, differentiated unit dispatch, flexibility-service compensation, plant efficiency, and coordination with distributed resources. The framework is transferable to other LNG-dependent coastal power systems seeking to reconcile reliability, affordability, and decarbonization.