Thermo-economic analysis of the energy storage role in a real polygenerative district

This paper presents a thermo-economic analysis based on data from a real Smart polygeneration microgrid (SPM), designed to satisfy energy demands of the university campus of Savona (Italy). The plant is made up of different cogenerative generators (micro gas turbines and an internal combustion engine), renewable generators and two auxiliary boilers (one of them is off during the most of the time): the generators are “distributed” around the campus and coupled to electrical and thermal storages. Since several cogenerative units are included in the grid, the integration of the different storage systems is relevant in order to determine the best management strategy, following both thermal and electrical requests and taking into proper account the strong difference between the two energy demand profiles. The thermo-economic analysis is performed exploiting the software W-ECoMP, developed by the authors’ research group, in order to find the best operational strategy, considering the importance of an appropriate storage system to manage the polygenerative energy district; attention is paid to the integration and combination of three different kinds of storage (hot and cold water tanks and electrical battery). Different scenarios are presented, combining the storages and showing their impact in terms of money savings and reduction of electrical energy purchasing from the National grid. Both the grid connected mode and island mode of operation of the SPM are considered. The analysis is performed considering the time dependent nature of the energy demands throughout the whole year and implementing the experimental off-design curves of the real devices installed in the grid.