Spain

Life Cycle Assessments (LCAs) are predominantly conducted using a static approach which aggregates emissions over time without considering emissions timing. Additionally LCAs often assume biogenic carbon neutrality neglecting site-specific forest carbon fluxes and temporal trade-offs. This study applies both static and dynamic LCA and incorporates biogenic carbon to evaluate the climate change impact of hydrogen production. It focuses on gasification of eucalyptus woodchips cultivated on former marginal grasslands (BIO system) which avoids competition with land used for food production. A case study is presented in western Andalusia (Spain) with the aim to replace hydrogen produced via the conventional steam methane reforming (SMR) pathway (BAU system) at La Rabida ´ refinery. The CO2FIX model was used to simulate biogenic carbon fluxes providing insights into carbon sequestration dynamics and it was found that the inclusion of biogenic carbon flows from eucalyptus plantations dramatically reduced CO₂ equivalent emissions (176 % in the static approach and 369 % in the dynamic approach) primarily due to soil and belowground biomass carbon sequestration. The dynamic LCA showed significantly lower CO₂ emissions than the static LCA (106 % reduction) shifting emissions from − 1.79 kg CO₂/kg H₂ in the static approach to − 3.69 kg CO₂/kg H₂ in the dynamic approach. These findings highlight the need to integrate emission dynamics and biogenic carbon flows into LCA methodologies to support informed decision-making and the development of more effective environmental policies.

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.

The transition to decarbonized energy systems positions hydrogen as a critical vector for achieving climate neutrality yet its large-scale transportation and storage remain key challenges. This study presents a comprehensive life cycle assessment (LCA) and economic analysis of large-scale H2 supply chains evaluating the liquid organic hydrogen carrier (LOHC) system based on benzyltoluene/perhydro-benzyltoluene (H0-BT/H12-BT) against conventional technologies: compressed gaseous hydrogen (CGH2) liquid hydrogen (LH2) and liquid ammonia (LNH3). The analysis includes multiple H2 transportation scenarios across Europe considering the steps: conditioning sea transportation post-processing and land distribution by truck or pipeline. Environmentally LOHC currently faces higher environmental impacts than CGH2 driven by energy-intensive dehydrogenation process. Truck-based distribution further amplifies impacts particularly over long distances while pipeline-based distribution significantly reduces the environmental burdens where infrastructure exists. Sensitivity analysis reveals that using H2 for dehydrogenation heat lowers process-level impacts but increases overall supply chain impacts questioning its net environmental benefit. Economically LOHC remains competitive despite high dehydrogenation costs benefiting from low sea transportation expenses compatibility with existing fossil fuel infrastructure and potential for future CAPEX and OPEX improvements. While CGH2 outperforms LH2 and LNH3 avoiding energy-intensive liquefaction and cracking its storage requirements add considerable costs. For land distribution LOHC trucks are optimal at lower capacities whereas repurposed natural gas pipelines favour CGH2 at higher scale reducing costs by up to 84 %. Despite current trade-offs the scalability flexibility and synergies with existing infrastructure position LOHC as a promising solution for long-distance H2 transport contingent on technological maturation to mitigate dehydrogenation impacts.

Hydrogen embrittlement (HE) can degrade the mechanical integrity of steel pipes increasing failure risks in naval fuel systems. This study assesses HE effects on ASTM A131 and A36 steels through tensile testing and numerical modeling. Tests conducted with varying exposure times to hydrogen revealed that A131 outperformed A36 in terms of mechanical strength. However both materials experienced property degradation after six hours. After nine hours a transient increase in strength occurred due to temporary microstructural hardening though the overall trend remained a decline. The maximum reductions in ultimate tensile strength and toughness were 19% and 47% for A131 and 39% and 61% for A36 respectively. Additionally microstructural analysis revealed the presence of inclusions intergranular decohesion and micro-crack in specimens exposed for longer periods. Finally a combined GTN-PLNIH numerical model was implemented demonstrating its effectiveness in predicting the mechanical behavior of structures exposed to hydrogen.