Browsing by Author "Swart, Liesel"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Sustainability assessment of technology systems that address the energy-water nexus: the case of desalination in the Western Cape
    (Stellenbosch : Stellenbosch University, 2017-12) Swart, Liesel; Brent, Alan C.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.
    ENGLISH ABSTRACT: In recent decades, the critical interdependencies that exist between the energy and water sectors, referred to as the energy-water nexus, have been investigated. It has become apparent that a policy change or intervention in one of the sectors can have a significant impact on the other. The impact on the entire energy-water nexus, therefore, needs to be considered when implementing changes in either sector. The Western Cape Province needs to increase its available water supply to ensure that the future water demand can be met. The aim of this research was to investigate the appropriateness of seawater desalination used in conjunction with renewable energy as a possible water supply intervention. The objectives of this research were to: select an appropriate modelling approach; compile, verify and validate the model; simulate different scenarios with and without the technology; and provide policymakers with recommendations regarding the sustainability of implementing a desalination technology system. It was determined that the Western Cape Province’s energy-water nexus is a complex system, because of the number of subsystems that exist within the system. A literature survey of the previous efforts that had been made to model similar systems was conducted. System dynamics modelling was found to be the most appropriate modelling tool, given the objectives of the research and the complexity of the problem. A systems thinking and modelling process was followed to develop a model of the Western Cape Province’s energy-water nexus. The first phase was problem formulation, and the second phase was the development of the conceptual model using causal loop diagrams. The construction, verification and validation of the dynamic computer simulation model was done in the third phase. Once confidence in the dynamic model was established, the fourth phase of the modelling process was completed. For this phase, a number of scenarios were developed and simulated to determine the effect of different desalination technology systems on the Western Cape Province. The impact of multi-effect distillation (MED) and reverse osmosis (RO) were compared. The effects of combining these technologies with different renewable energy sources, including thermal waste heat and solar energy, were also investigated. It was seen that the Western Cape Province’s water supply would be unable to meet the future water demand if no intervention was made. The results indicated that RO with photovoltaics would be the most sustainable and that the system’s life cycle cost up until 2040 is the lowest of all the simulated systems. In phase five, it was recommended to policymakers that, of all the systems that were considered, this system would be the best to implement. Additional water supply interventions, however, need to be investigated, as the recommended desalination system would not be enough to ensure sufficient future water supply. This research provides a better understanding of the complexities involved in the installation of a new technology system, such as desalination, in the Western Cape Province’s energy-water nexus. This research can be used as a platform to further explore the impacts of a desalination system or to investigate the sustainability of other technology systems that will affect the nexus.