The role of hydrogen transport infrastructure in system operation and flexibility under deep decarbonization

Hydrogen transport infrastructure is widely considered a key enabler of deep decarbonization. In Germany, the planned hydrogen backbone aims to connect industrial demand centers with renewable-rich regions. This study evaluates the system-level implications of a predefined hydrogen backbone using a high-resolution capacity expansion model of Germany, with particular emphasis on the post-gas phase-out period after 2045. Under a modest domestic hydrogen demand scenario without imports, results show that the backbone slightly reduces total system costs. However, its primary impact lies in reshaping the structure of system flexibility by shifting energy balancing toward spatially coordinated hydrogen production, storage, and conversion. This reduces pressure on AC transmission expansion and mitigates transition stress following the fossil phase-out. A targeted demand-side management (DSM) sensitivity further shows that temporal flexibility can reduce overinvestment during critical transition periods, highlighting the complementary roles of hydrogen transport infrastructure and demand-side measures in achieving climate neutrality.