Integration of electrodialysis with renewable energy sources for sustainable freshwater production: A review.

There is an increasing demand for clean water as the population of the earth is exponentially increasing. Many countries are facing water shortage problems, which are bound to become more prevalent in upcoming years. Therefore, it is necessary to investigate sustainable methods to produce clean water for drinking, irrigation, agriculture and domestic use. Electrodialysis uses electricity and specialized membranes to separate ionic substances from water. This practice can be used for desalination and wastewater treatment. To make the process more sustainable, electrodialysis can be coupled with renewable sources of energy such as solar and wind power. Photo-electrodialysis and photovoltaic-electrodialysis are two methods commonly used to couple solar energy with the electrodialysis process. However, these processes are dependent on the availability of sunlight and wind as weather conditions and the positioning of the sun vary by time. Electrodialysis is more favourable for brackish water desalination instead of seawater desalination as it has a lower energy requirement. Desalinating brackish water (1000-5000 ppm) has an energy requirement in the range of 0.4-4 kWh/m. This review paper summarizes the fundamental concepts of electrodialysis technology and its integration with renewable energy sources such as photo electrodialysis, photovoltaic assisted electrodialysis, reversible electrodialysis/electrodialysis and wind energy-driven electrodialysis. Some aspects that have been considered are the freshwater capacity, specific energy and costs of the hybrid systems.