This book involves the use of a thermodynamic concept called exergy analysis to analyse and optimize a Multi-Stage Flash desalination plant. Two different exergy models are used as a comparison; one that uses recently updated thermodynamic properties of seawater and another that models seawater as an electrolytic solution. The contents of this book are deemed important as the exergy analysis assesses the efficiency of a system, and is a tool that will be used in future sustainable development projects where the aim is to minimize our carbon footprint by creating more efficient systems. During the analysis of the desalination plant, the location of highest exergy destruction (lowest efficiency) is determined and compared to previous similar analyses. Knowing that decisions within industry will still be based on economic factors, thermoeconomics is seen as an important tool that combines both the thermodynamic and economic factors. It’s a tool that will be used for basing future environmental decisions by policy makers. This concept is introduced with an application of the theory used on results obtained in the exergy analysis.