Where does solar-aided seawater desalination make sense?A method for identifying sustainable sites

Global water planners are increasingly considering seawater desalination as an alternative to traditional freshwater supplies. Since desalination is both expensive and energy intensive, taking advantage of favorable natural and societal conditions while siting desalination facilities can provide significant financial and environmental returns. Currently, policy makers do not use a location-specific integrated analytical framework to determine where natural and societal conditions are conducive to desalination. This analysis seeks to fill that gap by demonstrating a multi-criteria, geographically-resolved methodology for identifying suitable regions for desalination infrastructure where 1) available renewable resources can offset part of the fossil energy load; 2) feedwater characteristics reduce the total energy needed for desalination; and 3) human populations have capacity and willingness to pay for desalinated water. This work demonstrates the method with a quantitative global analysis that identifies favorable sites for solar-aided seawater reverse osmosis desalination (SWRO) based on specific target criteria. Location-based data about natural conditions (solar insolation, ocean salinity, and ocean temperature) are integrated and mapped with social indicators (water stress, prevailing water prices, and population) to identify regions where solar-aided SWRO has the highest potential. This work concludes that water-stressed tropical and subtropical cities show the highest potential for economically sustainable solar-aided SWRO. © 2014 The Authors. Published by Elsevier B.V. Open access under CC BY-NC-ND license.

This work can aid policy makers by demonstrating a simple, customizable tool for identifying favorable locations for desalination facilities based on selected criteria. Here, the method was used to identify regions where on-site solar photovoltaic-aided seawater reverse osmosis makes sense: regions where natural conditions like ample sunshine and feed water characteristics could reduce the energy-related impacts of desalination, where societal conditions like water stress, water price, and concentrated populations could make desalinated water economical, and where these natural and societal conditions coincide. While this work uses a global resolution to identify broad regions where desalination could make sense, decision-makers can use this technique for real, specific projects by adding much more detailed criteria [21] and by engaging their communities to determine what criteria should be the basis for optimization. This work has demonstrated how an integrated GIS-MCDA framework can enable decision-makers to simultaneously incorporate economic, environmental, and other societally defined criteria when making desalination facility siting decisions. This example has also introduced the idea that GIS analysis can be used to find regions with feedwaters that are especially suited to desalination.