Design and analysis of a combined desalination and standalone CCHP (combined cooling heating and power) system integrating solar energy based on a bi-level optimization model

Water and energy supply are strongly interrelated on islands without power grid infrastructure and their efficient management can be achieved by integrating seawater desalination and solar energy into combined cooling, heating, and power (CCHP) systems. In this study, a bi-level optimization methodology is proposed to optimize a combined desalination and standalone CCHP system, which is assumed as installed on a remote South China Sea island. The traversing method and branch-and-bound method are used for solving the mixed-integer linear programming (MILP) optimization problem at the design and operation stages, respectively. The results indicate that the economic and environmental objectives determine the system configuration with the minimum and maximum capacity of each component. As the system configuration changes, the system energy efficiency exhibits a consistent change tendency with the carbon dioxide emission generally. It is also observed that the capacity of the electrical storage system (ESS) is no larger than that of the thermal storage system (TSS) because of the relative high cost-performance ratio of the ESS. The integrated desalination with the water tank proves to be effective for improving the system performance.