Energy use for membrane seawater desalination - current status and trends

Technological advances of membrane seawater desalination have propelled its worldwide use. Despite the two-fold reduction of its power demand over the past 20 years, seawater desalination remains the most energy intensive alternative for production of fresh drinking water at present. This article provides an overview of the current status of energy use for seawater desalination, discusses the minimum energy demand for production of fresh water and presents key factors that influence the desalination plant energy demand for the site specific conditions of a given desalination project. The article describes key benefits and challenges associated with the implementation of energy-saving technologies and equipment such as: collocation of desalination and power plants; alternative RO system configurations proven to yield significant energy savings such as; low-recovery plant design; use of split permeate two-pass RO system configuration; three-center RO system design; and use of high productivity/low energy membrane elements, hybrid RO membrane vessel configurations, large-size high efficiency pumps and pressure-exchanger based energy recovery systems. The article also discusses emerging desalination technologies with high-energy reduction potential and provides a forecast of the potential impact of future technologies on energy use for membrane desalination.