Identification of Prospective Areas in Water-Stressed Regions for Low-Enthalpy Geothermal Desalination

Abstract

Water scarcity is the lack of fresh water resources to meet water demand. It affects every continent and was listed in 2015 by the World Economic Forum as the largest global risk in terms of potential impact over the next decade. By 2025, an estimated 1.8 billion people will live in areas plagued by water scarcity, with two-thirds of the world's population living in water-stressed regions and approximately 780 million people without clean drinking water. Many solutions have been proposed to help combat this issue. One such solution is the use of desalination plants or systems to convert sea water or brackish water into fresh, usable water. Geothermal can help. The most effective method for geothermal desalination is to provide a low-enthalpy (70-90°C) geothermal heat source directly into a MED (multiple effect distillation) desalination plant avoiding the need for thermal storage. The geothermal heat source can be obtained using different methods such as: (1) drilling new wells in a proven resource area, (2) using existing geothermal wells that are actively used by the operators and not suitable for electricity generation, (3) using outlet brine from existing geothermal power plants, (4) utilizing waste heat from oil/gas wells. This paper summarizes the feasibility of implementing geothermal desalination units into various areas of the world effected by water scarcity. As an initial step, JRG Energy has developed a set of criteria for identifying locations within a country that are prospective to low-enthalpy geothermal desalination. The criteria include parameters for geothermal prospectivity (such as temperature, permeability, and fluid (groundwater), direct and indirect sources of heat, potential alternative heat sources such as abandoned oil and gas wells, and global areas of water need. We have prepared probability maps using spatial datasets and a GIS platform for 3 countries (Egypt, Saudi Arabia, and Vanuatu) that incorporate publicly-available data and existing maps of geothermal potential, source water, demand, and geo-political factors. The probability maps will be used to identify areas within the target countries that pose high likelihood of successfully implementing geothermal desalination plants and justify further site-specific feasibility studies. These maps and corresponding case studies will be presented at the conference.