NSGA-II-Based Techno-Economic Optimization of SMR and PV Hybrid Systems

This study examines the techno-economic performance of a hybrid energy structure incorporating small modular reactor (SMR) and photovoltaic (PV) systems during the phased decommissioning of coal-fired power plants in Türkiye. The study aims to progressively replace coal-based production with SMR and PV systems within the context of Türkiye's net-zero emission targets. To this end, a multiobjective optimization based on the Non-dominated Sorting Genetic Algorithm II (NSGA-II) was performed, considering the installation and operating costs of SMR and PV systems and coal fuel and carbon tax costs, with the goal of simultaneously minimizing total system cost and carbon emissions. The optimization results indicate that, under the considered annual planning assumptions, complete decommissioning of all coalfired power plants is not economically optimal due to the costemission trade-off. In the optimal scenario, the annual carbon emissions are calculated as 46.59 million tons, and the total installation cost is $46.83 billion. The levelized cost of energy (LCOE) excluding carbon tax is 60.16 $/MWh and becomes 89.27$/MWh when the carbon tax of 75$/tCO₂ is included, and the tax-excluded payback period is 4.8 years. HOMER Pro validation confirmed consistency in investment cost estimates, while differences in LCOE and emissions were mainly attributed to HOMER Pro's hourly dispatch structure, converter losses, and more detailed lifecycle cost modeling.