A novel thermoeconomic and environmental optimization of a solar-driven multi effect desalination–reverse osmosis–crystallizer cogeneration system: Design innovation, integrated analysis, and multi-objective performance enhancement

This study investigates the thermodynamic, economic, and environmental performance of a solar-driven polygeneration system integrating a Rankine cycle with multi-effect distillation (MED), two-stage reverse osmosis (RO), and a heat-integrated crystallizer for the simultaneous production of electricity, freshwater, and salt. The proposed polygeneration process employs parallel MED and first-stage RO units to enhance initial freshwater recovery, while concentrated brine streams are further treated through a secondary RO stage and a crystallizer to reduce liquid discharge. The system is modeled at an industrial scale using Aspen Plus, and its performance is evaluated through thermodynamic and exergoeconomic analyses, life cycle assessment (LCA), and multi-objective optimization using NSGA-II, MOPSO, and SQP algorithms. Under optimized operating conditions, the system is capable of producing approximately 49.6 MW of electricity, 76224 m 3 /day of freshwater, and 117 ton/h of salt. The freshwater production cost is reduced from 1.42 to 1.28 $/m³, while maintaining competitive economic indicators such as positive net present value and reasonable payback period. The results indicate that the integrated configuration can improve resource recovery and reduce environmental impacts compared to conventional fossil-based systems. However, the findings are based on steady-state modeling assumptions, and factors such as membrane fouling, transient solar variability, and operational uncertainties are not explicitly considered. Overall, the study provides a comprehensive framework for evaluating and optimizing large-scale solar-driven desalination and polygeneration systems.