Evaluating hydrogen transport scenarios at the Sicily gateway: Technical analysis of hydrogen-blended natural gas and dedicated hydrogen pipelines

This study evaluates two hydrogen-integration pathways for Sicily, a gateway of Italy's gas network: blending 20 vol% H 2 in existing natural gas pipelines and transporting pure hydrogen through a repurposed hydrogen backbone. Following the ASME (American Society of Mechanical Engineers) guidance, two operational set-points are considered, including pressure derating. A validated steady-state network model computes pressures, gas velocities and compressor power for each case investigated. For equal delivered energy to end users, hydrogen presence leads to higher velocities, pressure drops and compressor duties than natural gas only, with stronger penalties under pressure derating. In the hydrogen blending case, predicted velocities exceed commonly accepted limits. Annual transported hydrogen is about 0.7 Mt in the case of hydrogen blending scenario, and it increases to 2.5 Mt in the pure hydrogen backbone scenario. In this latter case, modeling the remaining natural gas system indicates roughly a 30% drop in gas transport capacity, implying the need for coordinated decommissioning or re-routing strategies during the transition period. • 20% hydrogen blending feasible in Sicily's gas network. • Blending raises compressor demand and increases gas flow velocity. • Repurposed pipeline carries 2.5 Mt/y hydrogen, blending allows only 0.7 Mt/y admixed. • Hydrogen blending is a practical pathway to start up the hydrogen supply chain. • Dedicated hydrogen corridors require major infrastructure and compressors substitution.