Water, water, everywhere …

“Water scarcity is one of the most serious global challenges of our time. Presently, over one-third of the world’s population lives in water-stressed countries and by 2025, this figure is predicted to rise to nearly two-thirds.” – M. Elimelech and W.A. Phillip, Science, 5 Aug 2011, p. 712, The Future of Seawater Desalination: Energy, Technology, and the Environment.

Many of these people find themselves in a situation not unlike that of Coleridge’s Ancient Mariner, surrounded by abundant seawater, but with limited or no access to freshwater (the poem says, “Water, water, everywhere, nor any drop to drink.”) . The dream for them is to convert seawater into fresh water through “desalination,” the removal of dissolved salts. “The Future of Seawater Desalination” describes the best practices for doing this (reverse osmosis), its energy requirements, possible enhancements through the development of new membrane materials, and whether desalination can ever be made sustainable.