Assessment of the water-energy-carbon nexus in energy systems: A multi-objective approach

This paper addresses the importance of thermal storage coupled to a combined heat and power systems using a multi-objective optimization approach. A nonlinear programming model is used for defining the size of a combined heat and power unit and thermal storage tank which supply energy utilities to a residential building. Water consumption, direct CO2 emissions generated by fuel consumption as well as global efficiency in energy supply are used as objective functions for addressing the water-energy-carbon nexus. In addition, total annual cost of the system is used for considering the economic performance of the system. Utopia tracking approach is used for defining a normalized approach for conducting an assessment of the economic-nexus performance. Results show the influence of thermal storage in reducing water consumption (15.5%) and emissions (67.5%) as well as improving efficiency (75%) of the system. The multi-objective analysis provides a systematic metric for the assessment of nexus, as well as a strategy for reaching trade-offs among the elements considered as part of the nexus and for identifying system performance limits for resources consumption.