A comprehensive review of energy consumption of seawater reverse osmosis desalination plants

High specific energy consumption (SEC) is the main barrier for the expansion of seawater reverse osmosis (SWRO). Therefore, the main objective of current SWRO research is to lower the SEC of SWRO plants. However, SEC of SWRO plants has not been systemically explored or analyzed, despite the need for information to develop appropriate strategies to reduce SEC. Therefore, this study aims to review and analyze SWRO plants for a comprehensive understanding of their SEC. First, trends in SWRO application are investigated using more than 70 datasets on large-scale SWRO. The analysis explains the increasing number of large-size SWRO plants, the SEC reduction by isobaric energy recovery devices (ERDs), and the use of different SWRO configurations to meet the energy and quality requirements. Factors associated with SEC (i.e., feed conditions, target conditions, and equipment efficiency) are also analyzed. High salinity increases energy demand, whereas the temperature effect on energy consumption is not entirely clear. High-efficiency ERDs and pumps can reduce SEC, but overall SEC cannot be explained by these factors alone. SEC is also affected by target water quality and quantity. Moreover, specific SWRO designs can improve the system to efficiently achieve the established goals. Furthermore, future directions to develop low-energy SWRO plants are discussed.