Design and Optimization of a Solar PTC-Based Cogeneration System for Sustainable Power and Freshwater Generation in Basrah

Water scarcity and rising energy demand in arid regions such as Basrah, Iraq, necessitate the development of highly efficient and environmentally responsible cogeneration systems. This study aims to design and optimize a solar-assisted power–water cogeneration system tailored to Basrah’s climatic and resource constraints. The proposed system integrates a Gas Turbine (GT) and Parabolic Trough Collector (PTC) solar field with a hybrid Multi-Effect Distillation (MED) and Reverse Osmosis (RO) desalination unit. A comprehensive 4E analysis (Energy, Exergy, Exergoeconomic, and Exergoenvironmental) is conducted to evaluate system performance. Thermodynamic modeling is performed using Thermoflex, and a Multi-Objective Genetic Algorithm (NSGA-III) implemented in MATLAB is employed to optimize key decision variables with the objectives of maximizing exergetic efficiency and minimizing total cost and environmental impacts. The optimized configuration increases exergetic efficiency from 47.31% to 60.12%, reduces total cost by 6.58%, and lowers environmental emissions by 4.27%. Furthermore, freshwater production rises from 120.10 to 142.87 kg/s, representing an 18.96% improvement. The novelty of this work lies in the integrated configuration coupling solar-assisted gas power with hybrid thermal-membrane desalination, specifically adapted to Basrah’s conditions. Combined with a full 4E assessment and advanced multi-objective optimization, this study bridges the gap between theoretical modeling and practical deployment in southern Iraq, demonstrating a technically viable and sustainable pathway for addressing the region’s critical water–energy nexus.