Laura Elizabeth Tizick

Hydrogen as a sustainable aviation fuel: Feasibility and implementation for RAF operations

The Royal Air Force (RAF) faces two critical challenges: safeguarding operational effectiveness in an increasingly volatile geopolitical world, whilst also pivoting to more sustainable operations. Aviation remains one of the hardest sectors to decarbonise due to its high energy demands and strict performance requirements.

Aviation is an important focus point for Defence, not only for improving its carbon footprint, but for safeguarding against future threats such as fuel price volatility and supply dependence, whilst also considering battlefield advantages of changing technology to support agile operations. To understand what options are available to the RAF, a structured comparison is needed to direct investment toward options that reduce climate impact without compromising war-fighting readiness.

Civil literature has matured vastly in terms of understanding sustainable alternatives in aviation, however it remains fragmented and disjointed for understanding the military use-cases. Studies have focused on passenger jet transport aircraft rather than the diversity of platforms the RAF must cater for. In the same vein, open-source military literature is focused on top level doctrine, strategic approaches and singular use cases of alternative technologies for specific platforms. This provides insight into the challenges the RAF may face on its decarbonising journey but does not resolve the problem of understanding specific trade-offs.

With hydrogen often cited as a long-term solution for civil aviation, this study applies a Multi-Criteria Decision Analysis (MCDA) tailored to RAF aircraft types and a back-casting horizon of 2050 (MOD, 2023). An Analytic Hierarchy Process (AHP) sets weightings for four main criteria (Technology, Operational, Economic and Environment) that reflect current defence priorities to understand where solutions excel or fall short in specific military requirements.

The results reveal that hydrogen performs poorly in a weighted AHP outcome, behind SAF and electric fuels. Scenarios and sensitivity analysis have confirmed that only a large increase in environmental weighting allows for electric to move ahead of SAF, whilst substantial improvements in hydrogen’s technology readiness levels are needed before it challenges SAF or electric for the UKs 2050 Net Zero goals. This study provides a comprehensive guide for considerations, providing advantages and limitations of each technology type. The research ultimately contributes to ongoing policy development within the RAF.