Photovoltaic-Driven Battery Deionization System for Efficient and Sustainable Seawater Desalination

Seawater desalination via electrochemical battery deionization (BDI) has shown significant potential for freshwater production. However, its widespread application has been limited by the high energy costs involved. To facilitate the commercialization of BDI technology, it is crucial to develop innovative integrated BDI systems that utilize sustainable energy sources and assess their practical performance for desalination of natural seawater. In this study, we construct the first photovoltaic-driven battery deionization system, termed PV-BDI, capable of continuously and simultaneously removing multiple ions from natural seawater. The system successfully produced freshwater with a total dissolved solids (TDS) level of 704 mg L^–1, meeting the maximum acceptable TDS limits recommended by the World Health Organization (WHO) for drinking water standards, which specify a maximum TDS limit of 1000 mg L^–1. The mass-specific energy consumption for salt removal to obtain drinking water from natural seawater via this system has been reduced to 0.036 kW·h kg^–1, surpassing the performance of other state-of-the-art PV-driven electrochemical-based desalination technologies such as electrodialysis and capacitive deionization (0.068–2.100 kW·h kg^–1). This work presents a pioneering proof-of-concept integrated PV-BDI system and demonstrates its practical performance for desalinating natural seawater, thereby laying the foundation for expanding BDI systems in the near future for environmentally friendly and sustainable industrial-scale seawater desalination.