Energy for desalination: A state-of-the-art review

The utilization of seawater for drinking purposes is limited by the high specific energy consumption (SEC) (kW-h/m³) of present desalination technologies; both thermal and membrane-based. This is in turn exasperated by high water production costs, adding up to the water scarcity around the globe. Most technologies are already working near their thermodynamic limit, while posing challenges in further SEC reductions. Understanding the current energy status and energy breakdowns of leading desalination technologies will further help in realizing limitations and boundaries imposed while working for improved system performances. This paper comprehensively reviews the energy requirements and potential research areas for reduced SEC of various thermal, membrane-based and emerging desalination technologies. For thermal desalination processes, which consume a large chunk of energy for heating, renewable energy sources can be a viable option for bringing down the energy requirements. Hence, this review also focuses on the potential of desalination-renewable energy integrations. The review extends beyond conventional energy reduction possibilities to utilizing novel, advanced membranes and innovative techniques for energy offsets. The future of desalination for optimized energy requirements is projected to include ultra-high permeability membranes, fouling resistant membranes, hybrid systems, and renewable-energy driven desalination.