Introduction: What is Sustainable Desalination?

The accelerated awareness of water's strategic value for national security has placed desalination in the heart of the food-water-energy nexus. In this chapter, an introduction is made to high-level sustainability appraisal of desalination from an ecological, economic, and social points of view drawing on the classical definition of sustainability. The energy efficiency and cost-effectiveness of desalination technologies have significantly increased over the past 30 years, and today commercial scale desalination plants exist in more than 150 countries, from Arabian Gulf States to European and Asian countries such as Spain, Portugal, Greece, China, and India. Innovative commercial projects and flexible funding schemes have driven the costs of desalination down to less than a dollar per cubic meter. However, the environmental impact of desalination, such as carbon emissions and the effect of brine discharge on the marine life, are still far from being mitigated. The use of renewable energy and zero-liquid-discharge technologies could perhaps be the much needed paradigm shift. But the cost entailed by such initiatives is still discouraging to investors. Finally, local and regional sociopolitical dynamics are all factors that can affect the sustainability of a desalination project. Experience has shown that fierce public opposition to new desalination plants is costly and time-consuming, even forbidding to the development of such plants. The interplay of all these parameters, whether environmental, economic, or sociopolitical in nature, should be kept in sight when the strategic decision is made to adopt desalination as a pathway to filling gaps in the water supply.