EVALUATING HYDROGEN BLENDING IN COUPLED LARGE-SCALE GAS AND ELECTRICITY NETWORKS

Sector coupling (SC) strategies, such as utilizing Power-to-Gas facilities to produce hydrogen and injecting it into the existing gas network could offer a rapid and viable approach to decarbonization and managing renewable energy sources (RES) curtailment. Nevertheless, research on real-world large-scale implementation and operational impacts remains limited. This study develops an integrated energy system model for Tuscany (IT), in which hydrogen, produced from curtailed renewable electricity, is injected into the primary high-pressure natural gas transmission pipeline. The main objective is to assess the operational impacts on both the gas and electricity networks and quantify the potential benefits in terms of curtailment reduction and electrolyzer power capacity deployment. The analysis explores two scenarios: the current regulatory hydrogen blending limit in Italy and a comparative scenario with an increased 10% volume threshold. Simulations were performed using the SAInt (Scenario Analysis Interface for Energy Systems) framework, which integrates a transient hydraulic simulation model for the gas network with a quasi-dynamic Alternating Current Power Flow (ACPF) model for the electric system. Our findings indicate that leveraging the main natural gas transmission pipeline can lead to a significant reduction in renewable energy curtailment, with a potential decrease of up to 68% under a 10% hydrogen blending scenario. Additionally, the results show that electrolyzer capacity deployment could reach an average of 41 MW per percentage point of hydrogen volume while ensuring compliance with gas network constraints. However, since hydrogen is not directly sourced from renewable plants, an increase in grid congestion can be observed in the power lines feeding the electrolyzer or in the substations of large renewable power plants due to their higher utilization.