A Review of Reverse Electrodialysis Process Simulation Approaches Applied to Concentrated Brines

Reverse electrodialysis (RED) is an emerging process intensification technology for sustainable energy generation from the salinity gradient between concentrated brines and dilute streams. Concentrated brines, generated in large volumes by seawater reverse osmosis (SWRO) desalination, mining operations, and saltworks, represent an abundant and underutilised resource whose energetic valorisation via RED can simultaneously reduce brine disposal impacts and contribute to decarbonising the water-energy nexus. This review critically examines existing simulation and modelling approaches for RED systems applied to concentrated brines, covering ion transport models, thermodynamic and exergy frameworks, semi-empirical stack models, multi-physics computational fluid dynamics (CFD), and data-driven machine learning (ML) methods. The review identifies the principal knowledge gaps limiting large-scale deployment: the incomplete description of multicomponent, multivalent ion transport in real brines; the translation of validated laboratory models to pilot and industrial stacks; and the absence of techno-economic and life-cycle analysis integrated with process models. Future research should focus on hybrid models that couple high-fidelity electrochemical simulation with experimental calibration, ML-accelerated parametric studies, and system-level integration of RED with reverse osmosis and membrane distillation. This work provides a structured assessment of current modelling capabilities and a roadmap for simulation-driven optimisation of RED technology.