Electrified desalination processes: Where we are and where to go from performance and economic perspectives

Water scarcity presents a pressing global challenge, profoundly impacting both human societies and environmental ecosystems. Brackish water and seawater desalination serve as a crucial solution to alleviate water stress. While pressure-driven membrane processes — reverse osmosis (RO) and nanofiltration (NF) — dominate the desalination market, electrified desalination processes have experienced substantial development in recent years, attributed to their improved scalability and reduced fouling tendencies compared to the pressure-driven technologies. However, their energy efficiency compared to RO remains a subject of debate, as reflected by the conclusions of numerous recent studies that have performed such comparisons. To settle this debate and provide more direct conclusions regarding the use of electrified technologies for desalination, this study conducts a comprehensive survey of electrified desalination processes reported in the literature over the last decades, focusing on key desalination parameters such as feed salinity, salt removal, water recovery, and water productivity. Based on the literature survey, we identify membrane capacitive deionization (MCDI), electrodialysis (ED), and flow-electrode capacitive deionization (FCDI) as the most promising electrified technologies. Employing mechanistic process modeling, we rigorously compare the energy consumption of electrified technologies with RO. Furthermore, we integrate this modeling with techno-economic analysis to evaluate the economic viability of various desalination technologies. Results demonstrate promising prospects for electrified technologies, demonstrating lower energy consumption and comparable economics of ED and FCDI relative to RO in brackish water desalination. Using our framework, we explore the impacts of material advancements on performance enhancement, emphasizing the importance of reducing manufacturing material costs rather than solely focusing on fabricating high-performance materials. Overall, our study highlights the significance of integrated mechanistic modeling and techno-economic analysis in assessing and guiding the future of electrified desalination technologies. Importantly, these insights extend beyond desalination to the broader water-energy nexus, offering valuable implications for sustainable water resource management.