Optimal combination of daily and seasonal energy storage using battery and hydrogen production to increase the self-sufficiency of local energy communities

Renewable Energy Communities (RECs) play an important role in driving the transition towards sustainable energy systems. In this context, energy storage systems are pivotal in mitigating fluctuations and uncertainties associated with variable renewable energy sources (VRES). Considering the variability of renewable energy generation and demand, it is imperative to conduct a comprehensive analysis under different conditions, investigating the roles of various energy storage systems in achieving optimal solutions. In this study, we propose an optimization framework for the optimal design and operation of energy systems combining both short-term and long-term energy storage technologies. The proposed framework integrates multi-objective optimization and multi-criteria evaluation to evaluate the potential of increasing the Self-Sufficient Ratio (SSR) of the system while minimizing the associated Levelized cost of exergy (LCOEx). Constraints are also defined in terms of maximal capacities of VRES production and energy storage. We provide Pareto frontiers allowing for the selection of compromises between SSR level and LCOEx. The systems include batteries, hydrogen production and storage, and thermal energy storage, achieving an SSR of 89%, around twice the SSR of a system with no energy storage. The results also reveal that hydrogen storage is required to reach SSR levels exceeding 60% and that its capacity increases with increasing VRES and storage availability. Lastly, this study delves into the synergistic interplay between local VRES and storage capacities in optimizing system performance, showing that both VRES and storage play significant roles in increasing the SSR of energy communities.