Could ammonia have a role in decarbonising aviation?

17th January, 2024

A new report by the Tyndall Centre for Climate Change Research at the University of Manchester for the Aviation Environment Federation (AEF) assesses the prospects for ammonia as a low-carbon fuel for aviation.

There are no perfect solutions for decarbonising flight – all options come with challenges and drawbacks – so, in addition to flying less, we need to carefully consider all options to deliver a net zero aviation sector.

Green hydrogen often appears in the media and in research programmes as one alternative fuel option that could zero-emissions flight if the current hurdles in terms of production, infrastructure and aircraft range can be overcome. But could ammonia also have a role? Despite being a commonly used chemical in other applications such as agriculture and plastics (albeit currently one that is fossil-derived), there is little research to date on its potential applications in aviation. 

Responding to this gap, AEF asked researchers from the Tyndall Centre for Climate Research to assess the prospects of ammonia as a potential fuel alternative for aviation.

This new report, ‘The potential role of ammonia as a low-carbon aviation fuel,’ reviews the current state of knowledge in relation to ammonia as an aviation fuel and pinpoints the knowledge gaps that require investigation before ammonia can be considered a viable option in aviation decarbonisation scenarios. 

This assessment finds that ammonia could have various applications in aviation (including ammonia cracking, as a hydrogen carrier, or in a fuel cell and has some advantages compared with hydrogen as it is easier to store and transport. Both hydrogen and ammonia are CO2-free in use. 

However, 

1. The overall technological readiness for ammonia-based fuels and their application in fuel cells is low. Further research into overall fuel performance, proper safety handling standards and accurate assessments of costs are necessary.
2. More regulations and policies are required to develop sustainability criteria for ammonia-based fuels. The different production routes and energy inputs for hydrogen as a feedstock and nitrogen fixation to make ammonia, along with the impact of nitrogen slippage as an indirect greenhouse gas, means standards are needed to ensure ammonia fuels are low-carbon enough. 

The report concludes that it is “too early to consider ammonia as a certain meaningful option within the scope of current decarbonisation pathways for aviation”. Nonetheless, it highlights the overall need for greater incentivisation for alternative fuel development through improved price signals or mandates. Without these interventions, the speed at which the necessary testing and supply chain development for ammonia and other alternative fuels will likely remain sluggish. 

Crucially, the considerations highlighted by the report demonstrate the scalability issues that plague most alternative fuels: insufficient green ammonia production is planned compared with demand. Consequently, it is of the utmost importance that demand management strategies are implemented alongside the development of alternative fuels.