RT info:eu-repo/semantics/article T1 From grey to “Green”: Modelling the non-energy uses of hydrogen for the EU energy transition A1 Campos Rodríguez, Juan Manuel A1 Capellán Pérez, Iñigo A1 Parrado Hernando, Gonzalo A1 Frechoso Escudero, Fernando K1 Green hydrogen K1 Decarbonisation K1 Industry K1 System dynamics K1 Bottom-up methodology K1 Policy assessment K1 33 Ciencias Tecnológicas AB Hydrogen (H2) used as feedstock (i.e., as raw material) in chemicals, refineries, and steel is currently producedfrom fossil fuels, thus leading to significant carbon dioxide (CO2) emissions. As these hard-to-abate sectors havelimited 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 oftransitioning from fossil-based methods to electrolytic H2 production for industrial feedstock. The regional modeladopts a bottom-up approach and is applied to the EU across five innovative decarbonisation scenarios, includingvarying 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 decarbonisationin 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. Themost effective CO2 emission mitigation occurs in growth-oriented ambitious decarbonisation ( 91 %) andDegrowth ( 97 %) scenarios. From a sectoral perspective, H2 use in steel industry achieves significantly greaterdecarbonisation ( 97 %). However, meeting electricity demand for electrolytic H2 (700–1180 TWh in 2050 for14–22.5 Mtons) in growth-oriented scenarios would require 25 %–42 % of the EU’s current electricity genera-tion, exceeding current renewable capacity and placing significant pressure on future power systemdevelopment. PB Elsevier SN 0306-2619 YR 2025 FD 2025 LK https://uvadoc.uva.es/handle/10324/78225 UL https://uvadoc.uva.es/handle/10324/78225 LA eng NO Applied Energy, 2025, vol. 397, p. 126325 NO Producción Científica DS UVaDOC RD 02-oct-2025