As global efforts accelerate the transition towards renewable energy sources and decentralized en- ergy systems, the challenge of managing surplus energy during off-peak hours becomes increasingly critical. Without effective and innovative storage solutions, excess capacity from renewable energy resources is being unexploited, reducing the efficiency and sustainability of these technologies. This thesis addresses this issue by proposing the integration of Shared Hydrogen Storage Systems (SHSS) within Energy Communities (ECs), providing a viable method for storing surplus energy as green hydrogen.

By converting and storing renewable energy into hydrogen, ECs can ensure a stable green energy supply, mitigating fluctuations and enhancing energy security. This research presents a modular energy-sharing architecture that integrates blockchain-based smart contracts, with algorithms for equitable distribution and trading of hydrogen capacity between community households. Simula- tions and case studies test the algorithms for hydrogen storage sizing and fair capacity allocation, while also exploring the potential of hydrogen-based heating systems.

The results showcase the critical role of hydrogen storage in increasing the efficiency of renewable energy systems, even during periods of low demand. Two models developed from the simula- tions demonstrate the practical dynamics of using hydrogen for long-term energy storage in urban environments. This work provides a framework for the practical implementation of shared hydro- gen storage for electrification and heating, contributing to the transition towards decentralized, carbon-neutral urban energy infrastructures.