Optimal energy hub design: Individual vs renewable energy community approaches in urban districts – The University of Genoa Opera Pia case study

In order to boost the integration of Renewable Energy Sources (RESs), the European Union has introduced Renewable Energy Communities (RECs), based on the sharing of energy within a set of members, that could be consumers, producers or prosumers; shared energy might also be incentivized. RECs could also include Battery Energy Storage Systems (BESSs) and Electric Vehicles (EVs) charging infrastructure: these sources are able to smooth the fluctuation of RES, also thanks to advanced charging patterns, like smart charging and Vehicle-to-Grid (V2G) or Vehicle-to-Building (V2B). This paper proposes an optimal design model for multiple energy hubs (i.e., a spatially bounded system converting, storing, and distributing multiple energy vectors to users), either operating independently or being joined in a REC virtually sharing energy through the distribution grid. The case study to which optimal design procedure is applied is the “Opera Pia” campus of the Polytechnic School of the University of Genoa. The considered technologies are PV modules, BESSs and Smart Chargers for EVs. Different scenarios are optimized, considering different electricity prices. Results show that, depending on the characteristics of the REC members and on the size of the installed technologies, self-consumption may prevail on energy sharing, thus leading to a limited beneficial impact of REC configuration. Sensitivity analyses to assess the impact of BESS and PV sizing on the energy performances of the REC are carried out. Smaller BESS installation costs lead to larger BESS capacities, that interfere with the virtual sharing mechanism of the REC, since they are used to store locally-produced energy; increasing the available surface for PV installation, the installed PV capacity increases, nevertheless not saturating the available space: shared energy trend is not proportional to it, since for larger PV capacities, shared energy is reduced (e.g., EV charging pattern is modified to exploit PV surplus, that is in turn not shared with other hubs).