Enhancing defossilization through optimal design of hydrogen infrastructures in energy communities

The defossilization of energy systems is a global priority for achieving a sustainable energy transition. Among the available technologies, hydrogen stands out as a key solution, offering long-term energy storage and supporting the decarbonization of conventional heating technologies. However, hydrogen infrastructures require significant investment and scale, making them particularly suitable for large consumers or aggregated users. In this context, renewable energy communities (RECs) represent an ideal framework to exploit the potential of hydrogen, as they integrate local renewable generation, storage, and energy sharing among members. A critical factor for the success of such integrated solutions is the optimal design and sizing of energy assets. Inappropriate sizing can lead to inefficiencies, higher costs, and sub-optimal performance, highlighting the need for advanced design tools. While existing research on REC optimal design mainly deals with electricity, it is essential to consider them from a sector integration perspective. This study introduces an innovative optimization framework based on a Mixed-Integer Linear Programming approach, designed to determine the optimal sizing of energy conversion and storage units in the context of multi-vector RECs, including the calculation of shared energy flows. The integration and performance of hydrogen technologies for seasonal storage into the community energy mix are investigated. The objective function of the optimization is the minimization of carbon dioxide emissions, promoting environmentally sustainable solutions. The developed tool is applied to a real-world case study which includes a university campus and a research institute in Italy, with a specific focus on assessing the role of hydrogen systems in the presence of a growing penetration of renewable energy. The results of yearly optimization reveal that the inclusion of hydrogen reduces natural gas use and electricity purchased by up to 16 % and 37 %, respectively. The hydrogen infrastructure operates as seasonal storage for renewable electricity, covering up to 11.5 % of heating demand, and supports the defossilization of the REC through an 8 % reduction in carbon dioxide emissions, which cannot be achieved in the scenarios without the integration of hydrogen.