Energy-water nexus: renewable-integrated hybridized desalination systems

Increased water scarcity across increasing world populations has led to a greater demand for desalination. However, the energy intensity and subsequent high costs of desalination remain the main barrier for widespread deployment of desalination systems. Add to this, the sustainability concerns of fossil fuel energy sources. This challenge has led to focused international research on the energy-water nexus. In recent years, several types of renewable energy have been integrated with a variety of desalination processes. Various large-capacity, renewable-desalination (RE-desalination) plants have been built across the world, especially in Middle Eastern countries, where water is relatively scarce and renewable resources are abundant and accessible. In addition, the reduction in the cost of photovoltaic (PV) panels by almost 80% over the last decade has contributed to their greater economy and wide deployment worldwide. For remote areas, it is now reasonable to consider offgrid, small-capacity RE-desalination systems, since in these regions transportation of fuel or water and connection to the grid are prohibitively expensive or impractical. Various renewable energies-such as solar, wind, and geothermal-can be coupled with many desalination methods, based on the availability of these resources in different locations, and also on other factors such as reliability required or the capital cost of establishment. This chapter reviews these various methods of desalination and configurations of RE-desalination systems currently in use, or under development. In addition, the issues relating to grid connectivity of RE-desalination systems and the economy of grid connection versus complete or partial energy independence are explained.