Optimal Planning of Low Carbon Microgrids Using Primary Energy Savings as a Constraining Factor: The Case of an Industrial Retrofit

Microgrids are recognized as effective solutions to address the urbanization challenges, promoting the diffusion of DER and the realization of low carbon districts. The optimal design of microgrids, served by complex mixes of energy systems, can be modeled as an optimization problem that, once solved, grants decision making support to urban planners and engineers. This work presents a methodology to promote the economically optimal and sustainable design of microgrids, using the Primary Energy Savings (PES) as a constraining factor. A Mixed Integer Linear Programming (MILP) formulation is implemented and tested on a retrofit scenario, using actual data from an industrial microgrid. The optimal energy mix is analyzed as it changes accordingly to the technical, economical and sustainability constraints enforced. A sensitivity analysis on the PES constraint factor highlights how aiming to an environmentally friendly design substantially affects the optimal energy mix of the microgrid. In particular, forcing a low carbon design, the optimization tool promotes the installation of a polygeneration system, in this case in a heat-lead design.