Optimal scheduling of energy and mass flows based on networked multi-carrier hubs formulation: a general framework

Due to increased energy demand and environmental concerns such as greenhouse gas emissions and natural resources depletion, optimizing energy and raw materials usage has recently drawn much attention. Achieving more synergy between different energy sectors and manufacturing processes could lead to substantial improvements. Energy hubs are already well-known solutions for studying multi-carrier energy systems. In the present study, a multi-carrier hub is defined as a geographic area where different processes take place to convert energy and material flows possibly consumed locally, stored, or exported. Hub boundaries correspond to an area small enough to neglect losses when energy and materials flows are exchanged between the processes. A general formulation is introduced to model such a hub. This formalism encompasses all the possible configurations without limitations or preconceptions regarding used carriers or processes' architecture. For this purpose, a new hub representation is proposed that allows optimization while considering all possible arrangements (parallel, serial, or a combination of them). It is implemented in a framework that allows the creation of several multi-carrier hubs and connecting some of them to exchange flows through dedicated networks. The formalism is based on linear programming (LP). The features of the developed framework are illustrated by a case study consisting of a network made of three hubs and considering heat, electricity, water, and hydrogen flows.The study aims to optimally schedule processes usage and materials and energy storage to minimize the cost of imported resources. The study is done in a short-term period. It shows the benefits of synergy between the different processes in the hub.