From grey to “Green”: Modelling the non-energy uses of hydrogen for the EU energy transition

Hydrogen (H2) used as feedstock (i.e., as raw material) in chemicals, refineries, and steel is currently produced from fossil fuels, thus leading to significant carbon dioxide (CO2) emissions. As these hard-to-abate sectors have limited electrification alternatives, H2 produced by electrolysis offers a potential option for decarbonising them. Existing modelling analyses to date provide limited insights due to their predominant use of sector-specific, static, non-recursive, and non-open models. This paper advances research by presenting a dynamic, recursive, open-access energy model using System Dynamics to study long-term systemic and environmental impacts of transitioning from fossil-based methods to electrolytic H2 production for industrial feedstock. The regional model adopts a bottom-up approach and is applied to the EU across five innovative decarbonisation scenarios, including varying technological transition speeds and a paradigm-shift scenario (Degrowth). Our results indicate that, assuming continued H2 demand trends and large-scale electrolytic H2 deployment by 2030, grid decarbonisation in the EU must accelerate to ensure green H2 for industrial feedstock emits less CO2 than fossil fuel methods, doubling the current pace. Otherwise, electrolytic H2 won't offer clear CO2 reduction benefits until 2040. The most effective CO2 emission mitigation occurs in growth-oriented ambitious decarbonisation (−91 %) and Degrowth (−97 %) scenarios. From a sectoral perspective, H2 use in steel industry achieves significantly greater decarbonisation (−97 %). However, meeting electricity demand for electrolytic H2 (700–1180 TWh in 2050 for 14–22.5 Mtons) in growth-oriented scenarios would require 25 %–42 % of the EU's current electricity generation, exceeding current renewable capacity and placing significant pressure on future power system development.