Hybrid energy networks, i.e. the integration of electricity, heat and gas networks, can make a decisive contribution to optimizing the energy system. The IEA DHC Annex TS3 analyzes the potential and challenges of hybrid energy networks from the point of view of the district heating/cooling system. In this project, the Energieinstitut focused on the interaction between the heating network and hydrogen production, published at https://doi.org/10.1016/j.ijhydene.2021.06.233