Designing Desalinated Water Supply Systems

Abstract

The incorporation of desalinated water supply systems is seen as an option to address water scarcity in non-coastal regions but several technical, economic, environmental, and social challenges must be considered in the design stage. With this in mind, this dissertation aims to accomplish the following research objectives: 1) to determine new approaches for designing desalinated water supply systems in non-coastal regions suffering from water scarcity and 2) to determine the main impacts generated by desalination plants used for facing water scarcity in non-coastal regions considering Chile as a case study. The research methodology applied for achieving these objectives was developed in three stages: 1) an optimization approach; 2) a water assessment method; and 3) a participatory modelling framework. The main results obtained in this research project are two new optimization approaches capable of evaluating hundreds of design alternatives of desalinated water supply systems in a short time and selecting the best solution among them considering an objective determined. The results also demonstrate that seawater desalination is impacting in reducing water stress levels in some regions of Chile, specifically in Chilean mining regions, and that the environmental impact generated by the greenhouse gas emitted for the operation of all desalination plants installed in the country will contribute to less than 1% of the total greenhouse gas emitted in Chile by 2030. Furthermore, it is possible to indicate that receiving feedback from stakeholders during the participatory modelling framework was key to improving the interaction of the users with the optimization approaches proposed and to incorporating other elements of analysis such as the penalties associated with using protected and unprotected but culturally important methods, among other elements. The main contribution of this research is the inclusion of greenhouse gas emissions quantification. These emissions are generated during the operation of desalination plants. This aspect has been added to the assessment of water scarcity, using the Water Stress Indicator adopted by the 2030 Agenda for Sustainable Development. Additionally, the research developed new optimization approaches. These approaches are for designing integrated desalinated water supply systems. The systems aim to meet the water demand of more than one user in non-coastal regions considering economic and environmental aspects. Additionally, the involvement of stakeholders has improved understanding of the relationships between the components of these systems and it also shown that assessing trade-offs between key actors can greatly help in determining optimal desalinated water supply systems at regional level.