Potential of ammonia as hydrogen storage for future electrified aircraft

The implementation of hydrogen as a clean aviation energy vector faces challenges in onboard storage and transportation due to its low volumetric energy density and the strict weight and space constraints of aircraft. This study introduces a breakthrough approach, leveraging liquid ammonia as a hydrogen carrier for electrified aircraft propulsion, an area largely unexplored compared to land and maritime applications. Ammonia’s high hydrogen content, ease of storage, and existing infrastructure make it a compelling alternative to conventional hydrogen storage methods. An integrated system design is presented, combining ammonia storage, a high-efficiency cracking reactor for on-demand hydrogen release, and a purification unit ensuring compatibility with the conversion system, which consists of proton exchange membrane fuel cells (PEMFCs) and their associated balance-of-plant components. To optimize performance and reduce the overall system footprint, a thermal integration strategy is implemented. The paper provides a quantitative assessment of the system’s feasibility in a regional aircraft, demonstrating a gravimetric hydrogen storage index of 9.1%, rivaling state-of-the-art physical storage solutions, and identifying key technological gaps that must be overcome to enhance system performance and competitiveness with conventional kerosene-based propulsion. By addressing the specific challenges of hydrogen storage in aviation, this work provides new insights into the potential of ammonia-based systems and their role in advancing sustainable airborne propulsion technologies.