The global imperative to decarbonize the aviation sector, a particularly challenging industry to abate, has placed hydrogen (H₂) as a cornerstone of future propulsion strategies. While fuel cells are increasingly recognized as a viable alternative to combustion engines, offering electric propulsion with zero CO₂ and high efficiency, their widespread adoption is critically dependent on the efficiency and sustainability of H₂ production pathways. A comprehensive, quantitative analysis by researchers from the University of São Paulo (USP) establishes a consolidated roadmap, comparing conventional thermal reforming with emerging electrochemical routes to identify realistic transition pathways toward Sustainable Aviation Fuels (SAF). The study, conducted in collaboration with the Research Centre for Greenhouse Gas Innovation (RCGI), highlights electrochemical reforming (ECR) as the most compatible and sustainable solution for this demanding sector. The core challenge lies in displacing steam methane reforming (SMR), which, despite being the source of approximately 96% of global H₂ production, remains economically dominant but environmentally constrained. SMR operates at high temperatures (700 to 1000 °C) and is carbon-intensive, generating 9–12 kg CO₂ per kg H₂. In sharp contrast, ECR enables low-carbon H₂ generation under mild conditions, operating at only 50 to 90 °C. This low-temperature operation dramatically reduces the complexity and energy losses associated with thermal pathways.

The greatest implication of ECR for aviation is its ability to overcome the critical bottleneck of H₂ storage. Storing liquid hydrogen (LH₂) requires cryogenic temperatures (< 20 K) and necessitates tanks up to four times larger, imposing significant structural, safety, and cost penalties on aircraft and airport operations. ECR eliminates the need for H₂ storage entirely by producing the fuel in situ (onboard or at airports) from liquid alcohols such as bioethanol. Ethanol is liquid at ambient conditions and is compatible with existing kerosene logistics and infrastructure, minimizing retrofit costs and mitigating the substantial safety and volumetric constraints associated with LH₂ containment.

Although conventional reforming remains the economic baseline, the analysis provides quantifiable thresholds for ECR’s commercial viability. A sensitivity analysis demonstrates that ECR could reach cost parity with SMR under two conditions: a 60% reduction in electrocatalyst costs or renewable electricity prices falling below 0.03 USD·(kW·h)⁻¹ . These quantitative boundaries, coupled with ECR’s suitability for modular and decentralized production, define an actionable, engineering-based framework for stakeholders. The findings confirm ECR as a scalable, low-carbon, and infrastructure-compatible alternative for aviation decarbonization, paving the way for hybrid-electric aircraft architectures that utilize liquid bioethanol as a primary energy carrier.

The study identifies the integration of ECR with fuel cells as a strategic pathway for aviation, enabling hybrid-electric aircraft that use liquid ethanol as the primary energy carrier and convert it into electricity in real time during flight. Such a system eliminates the weight and safety challenges of cryogenic hydrogen storage while maintaining the high energy density required for long-range aviation. By defining clear thermodynamic and economic thresholds, the analysis provides an engineering-based framework to guide policy and industrial investment in hydrogen aviation.

The paper “A Comparative Analysis of Conventional Thermal and Electrochemical Reforming Pathways for Hydrogen Production Towards Sustainable Aviation Fuels (SAF),” is authored by Leandro Hostert, Naiza Vilas-Bôas, Julio R. Meneghini, Edson A. Ticianelli, Hamilton Varela. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.10.028. For more information about Engineering, visit the website at https://www.sciencedirect.com/journal/engineering.