Aviation Fuel Demand Doesn’t Collapse. Cheap Kerosene Growth Does.

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Aviation is one of the harder transition sectors to model well because it invites two bad shortcuts. One is to assume that flying keeps growing as it did in the cheap-kerosene era, with a cleaner molecule somehow dropped into the same demand curve. The other is to assume that decarbonization or post-COVID behavioral change makes aviation demand collapse. Neither is a good starting point.

COVID did not permanently break aviation. Fuel demand recovered enough that any serious long-term projection has to start from that reality, not from a pandemic trough. People still fly for family, migration, business, holidays, emergencies, remote communities, islands, medical needs, and simple curiosity. Aviation provides real mobility services, and those services do not disappear because aviation is hard to decarbonize.

But recovery is not the same thing as a return to cheap kerosene growth. The old aviation model was built around abundant, energy-dense, relatively cheap liquid fossil fuel. That fuel shaped aircraft design, airline economics, hub networks, ticket prices, route structures, and expectations about growth. Once the sector has to absorb sustainable aviation fuel mandates, lifecycle emissions rules, carbon prices, feedstock constraints, synthetic-fuel costs, and more scrutiny on avoidable flying, the fuel-service curve changes.

The useful question is not “what replaces kerosene?” It is “which aviation services still need liquid fuels, which can electrify, and which demand disappears or shifts when the true cost of fuel shows up?” That is the denominator problem. Aviation is not a single fuel demand block. It is a set of route lengths, aircraft sizes, airport pairs, customer types, and service needs.

The split starts with distance. Shorter routes are where batteries and hybrid-electric aircraft have the best chance of changing the economics. Under roughly 1,000 kilometers, and especially on regional routes with weak rail alternatives, existing airports, short stage lengths, and high fuel-cost exposure, electric or hybrid-electric aircraft can plausibly create cheaper operating costs and new service patterns. That does not mean every short route electrifies quickly. Certification, aircraft availability, charging infrastructure, airport operations, winter performance, reserve margins, and airline adoption all matter. But it does mean that the short-route denominator should not be treated as a permanent liquid-fuel market.

That is a very different claim from the old urban-air-mobility fantasies. The aviation segment worth watching is not fleets of novelty aircraft buzzing across dense cities. It is regional mobility: thinner routes, smaller aircraft, lower energy cost, existing airports, and places where rail is absent, weak, slow, or politically unlikely. In those markets, electricity may not just reduce emissions. It may expand useful service.

Longer routes are different. Once aircraft get larger and distances get longer, the physics of energy density keeps liquid fuels in the picture. Batteries are improving, but they do not turn a transcontinental or intercontinental jet into an electric aircraft in any useful planning horizon. Hydrogen does not solve the problem either. It imposes major aircraft-volume penalties, airport-infrastructure burdens, safety and handling complexity, and weak system economics compared with batteries for shorter routes and sustainable liquid fuels for the hard-to-electrify remainder.

That leaves aviation with a constrained liquid-fuel future. Sustainable aviation fuels will matter. So will some synthetic fuels in high-value or policy-driven contexts. But they are not cheap kerosene with better branding. Biofuel feedstocks are limited and contested. Synthetic fuels are electricity-intensive and expensive. Lifecycle accounting will get tighter. Mandates will raise costs. Airlines will pass some of that through to passengers and absorb some through network changes, efficiency, and fleet choices.

The result is not aviation collapse. It is aviation stratification. Some shorter routes electrify and may grow because operating costs fall where the technology fits. Some medium-haul and long-haul flying persists but becomes more expensive as liquid fuels decarbonize. Some marginal leisure demand is destroyed by higher prices. Some business travel remains permanently displaced by videoconferencing and changed corporate habits. Some trips shift to rail where rail is good, which mostly means dense corridors with existing or plausible high-quality service. A great deal of aviation still remains because no other mode can perform the same service.

This is why fuel demand can flatten or decline without aviation disappearing. The industry can keep moving people and goods while the fuel-service mix changes underneath it. Shorter-route electricity reduces liquid-fuel demand at the margin. Efficiency continues to matter. Load factors, aircraft utilization, route planning, and fleet renewal matter. Higher liquid-fuel costs suppress some growth. The sector does not need a single miracle fuel to change its trajectory.

The policy implication is straightforward. Do not model aviation as if today’s kerosene curve simply continues until hydrogen, ammonia, synthetic fuels, or offsets arrive to rescue it. Start with services. Separate short regional routes from long-haul fuel demand. Test where electric aircraft can actually earn their way into service. Treat sustainable aviation fuels as scarce and valuable, not infinite. Keep hydrogen out of the base case until it survives aircraft, airport, cost, and safety filters. Use carbon pricing and lifecycle standards to make fossil kerosene less artificially cheap.

There is also an investment lesson. The aviation transition is not one market. Electric regional aviation, airport charging, SAF supply chains, feedstock logistics, carbon accounting, fleet efficiency, rail substitution, and long-haul fuel procurement all have different risk profiles. A company or policy that sounds relevant to “aviation decarbonization” may still be pointed at the wrong part of the denominator.

My updated aviation fuel-demand pathway starts from the corrected post-COVID baseline and works forward from fuel service rather than fuel substitution. Aviation demand does not collapse. Cheap kerosene growth does. That distinction is the difference between a model that flatters incumbent assumptions and one that starts to describe the transition that is actually plausible.

Read the full TFIE Strategy Briefing analysis:

Aviation Fuel Demand Doesn’t Collapse. Cheap Kerosene Growth Does.

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