Water-energy-carbon nexus : a system dynamics approach for assessing urban water systems

Water, energy, and carbon emissions of Urban Water Systems (UWSs) are intertwined and have complex interactions forming a water-energy-carbon (WEC) nexus. A comprehensive methodology to quantify dynamic WEC nexus is required. The main objective of this research is to develop a decision support system (DSS) for assessing the WEC nexus for sustainable planning and management of UWSs. This research has been accomplished in five distinct steps. In the first step, key Sustainability Performance Indicators (SPIs) of small to medium-sized UWSs have been identified. The SPIs related to water consumption, energy use, carbon emissions, and cost were used for developing the DSS. In the second step, a WEC DSS has been developed for an operational phase of an UWS using system dynamics and then applied to the City of Penticton. The highest energy consumer was found to be indoor hot water use in the city. In the third step, a framework has been developed to study the impacts of neighbourhood densification on the WEC nexus. A higher net residential density will result in lower per capita water demand, energy use, net carbon emissions, and life cycle cost of water distribution system. The proposed framework provides an optimal residential density and energy intensity of water distribution, which can be used as inputs to the WEC DSS. In the fourth step, microbial water quality guidelines for reclaimed water have been developed for various non-potable urban reuses. Moreover, the FitWater tool has been developed for evaluating fit-for-purpose wastewater treatment and reuse potentials based on cost, health risk, and the WEC nexus. The outputs of FitWater can be used as inputs to the WEC DSS. In the last step, the economics of the WEC nexus of net-zero water communities has been analyzed using the WEC model. The DSS developed based on this research is capable of quantifying dynamic water consumption, energy use, carbon emissions, and the cost of UWSs. The DSS can analyze different WEC-based interventions. The DSS can be used by utilities, urban developers, and policy makers for long-term planning of urban water in communities.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat