Hydrogen technology pathways in metropolitan energy systems: An application to Montréal

Low-carbon hydrogen is increasingly considered a key option for decarbonizing hard-to-abate sectors, yet most transition analyses are conducted at national or global scales, with limited attention to metropolitan energy systems where climate policies are implemented. This paper examines how hydrogen can contribute to urban decarbonization under multi-level climate governance by extending the Energy Technology Environment Model (ETEM) to integrate full hydrogen supply chains and applying a structured downscaling approach to translate national and provincial data to the metropolitan scale. The framework is applied to the Montréal Metropolitan Community (CMM), a member of the C40 Cities network, to evaluate hydrogen deployment under different decarbonization scenarios. Results show that under full carbon neutrality constraints, hydrogen reaches approximately 7% of total final energy consumption by 2050, with total production exceeding 33 PJ, yet uptake remains concentrated in heavy industry and hard-to-electrify transport, underscoring hydrogen's role as a targeted complement to electrification rather than a dominant energy carrier. As climate constraints tighten, hydrogen production shifts toward electrolysis and CCS-enabled pathways, with deployment increasing significantly after 2040. Carbon neutrality further requires a minimum direct air capture capacity of 1 MtCO₂/year to offset residual emissions from sectors where abatement through fuel switching alone is technically infeasible. The proposed modeling framework is designed to be adaptable to other metropolitan regions and C40 cities with similar data infrastructure, offering a structured approach for assessing hydrogen integration in urban energy transitions.