Renewable–diesel-powered multi-element series SWRO for off-grid Sinai resorts: A multi-objective optimization for cost‑carbon minimization

Water scarcity in remote and off-grid regions necessitates sustainable and low-carbon desalination solutions. This study develops a multi-objective optimization framework for a hybrid renewable–diesel powered serial multi-element seawater reverse osmosis (SWRO) desalination system (1–4 elements in a single pressure vessel), integrating photovoltaic (PV) panels, wind turbines, batteries, and a diesel generator. The framework simultaneously minimizes the levelized cost of water (LCOW) and annual carbon emissions (ACE) using three advanced metaheuristic algorithms NSGA-II, Particle Swarm Optimization (PSO), and, for the first time in this context, the Multi-Objective Artificial Rabbit Optimizer (MO-ARO). A fuzzy decision-making approach is applied to identify the most balanced solutions along the Pareto front. The framework is validated and applied to nine representative sites in the Sinai Peninsula, Egypt, characterized by diverse solar and wind resources. Results show that four-elements RO configurations reduce LCOW by approximately 45 % (2.48–2.7 $/m³) and ACE by 50 % (27–34 Tons/year) compared with single-element designs, while also lowering PV and battery requirements by up to 50 %. Maintaining a constant diesel contribution of around 3 % provides the optimal trade-off between cost and emissions, ensuring reliable operation with minimal environmental impact. These findings highlight the potential of hybrid renewable–diesel serial multi-element SWRO systems to deliver low-carbon and economically viable desalination for off-grid communities, contributing to sustainable water–energy management.