Assessment of hydrogen-based long term electrical energy storage in residential energy systems

Among the numerous envisioned applications for hydrogen in the decarbonisation of the energy system, seasonal energy storage is usually regarded as one of the most likely options. Although long-term energy storage is usually considered at grid-scale level, given the increasing diffusion of distributed energy systems and the expected cost reduction in hydrogen related components, some companies are starting to offer residential systems, with PV modules and batteries, that rely on hydrogen for seasonal storage of electrical energy. Such hydrogen storage systems are generally composed by water electrolysers, hydrogen storage vessels and fuel cells. The aim of this work is to investigate such systems and their possible applications for different geographical conditions in Italy. On-grid and off-grid systems are considered and compared to systems without hydrogen, in terms of self-consumption ratio, size of components and economic investment. Each different option has been assessed from a techno-economic point of view via MESS (Multi Energy Systems Simulator), an analytical programming tool for the analysis of local energy systems. Results have identified the optimal sizing of the system's components and have shown how such systems are not, in general, economically competitive for a single dwelling, although they can in some cases ensure energy independence.