When looking at the future development of aircraft engines and fuel, the infrastructure to deliver it is as important as the technology. There are some options for SAF as usage increases, but significant changes are needed if the industry is to move further to adopt hydrogen as a fuel source.
Guides For Aviation Fuel
Improving Aviation Efficiency & Emissions
The aviation sector has committed to halving net carbon dioxide emissions by 2025 (based on 2005 levels). To achieve this, significant changes are needed. Engine technology and efficiency have been improving for many years – and have been a driving force of aircraft upgrades for decades.
Changes to fuel have been slower. It is only in recent years that standard kerosene fuel has begun to be supplemented with Sustainable Aviation Fuel (SAF). The uptake of SAF is low but growing (some estimates are that it accounts for only around 0.01% of aviation fuel use currently). Challenges include the high cost of production and the distribution network. Both of these should ease as usage and likely legislation develops.
An interesting report by the US National Renewable Energy Laboratory looked in depth at the distribution system for SAF. Jet fuel is produced in batches, with each production undergoing stringent testing and certification. The same applies to SAF. Currently, most SAF delivery in the US is by truck, whereas jet fuel uses pipelines – largely due to the different production sites. As volumes increase, existing infrastructure could be used for SAF, and blending locations could shift, lowering costs and simplifying distribution.
Switching to Hydrogen is Even More Complex
Longer-term, the aviation industry is looking at the possibilities of moving away from hydrocarbon fuels entirely. Electric engines, using stored battery power, are one option. This is likely only to suit smaller aircraft, though. Hydrogen has more potential for larger aircraft.
Work on hydrogen propulsion is well underway, and there have been working examples before. Airbus is likely furthest ahead in commercial aircraft, with their ZEROe range of aircraft. A first version is expected to be operational by 2035.
Hydrogen though presents a real “chicken and egg” scenario. Storage and delivery infrastructure is a major challenge. This will require an entirely new development at airports – and will have to operate alongside existing aviation fuel systems. Aircraft manufacturers will want to see commitments to infrastructure at airports before developing aircraft, and airports will want a commitment for usage. This is likely to be a challenging situation and one that will require global investment and collaboration.
Airbus CEO Guillaume Faury explained this in September 2021. He said:
“I am confident that Airbus can deliver on that commitment [of a hydrogen-fueled airliner entering into service in 2035], but the airplane is only part of the challenge. We can’t do it alone.”
Making Early Progress
Some progress has been made in Europe especially. France’s Lyon-Saint Exupery Airport will become a pilot airport for hydrogen supply in 2023. On a larger scale, Airbus, Air France-KLM, and Paris airports are planning to work together to create a hydrogen hub in Paris. This could work well for local and regional flights, but expansion will be needed to enable longer flights.
Public sector investment and support could take this even further. Buy-in and support from regulators and governments will undoubtedly be needed. The problem, though, is a global one, and for real progress to be made, manufacturers and airlines will want assurances of globally available infrastructure.
Final Thoughts
Moving to alternative fuel sources is a significant part of aviation’s commitment to emissions reduction. The use of SAF is underway, and we will likely see this expand in the coming years. With infrastructure challenges, the shift to hydrogen as a fuel source will take much longer. It will be some time for hydrogen-powered aircraft to become dominant in airline fleets.
