E-kerosene scalability: the bottleneck in clean aviation

It is trying to build an entirely new fuel system while conventional aviation already consumes energy at industrial scale.

E-kerosene, also called Power-to-Liquid or PtL synthetic aviation fuel, has an important advantage: it does not depend on a limited stream of used cooking oil, agricultural residues, or other biogenic feedstocks. It can be produced from renewable electricity, green hydrogen, and captured carbon dioxide. In principle, that makes it a feedstock-unconstrained replacement for fossil jet fuel.

In practice, the constraint shifts from biomass to infrastructure. The process requires large volumes of clean power, electrolyzers, carbon capture, synthesis equipment, storage, transport, and aircraft-fuel certification. Each component is technically available. The integrated system is not yet available at the required scale.

The energy density gap: why liquid fuels remain indispensable

The most persistent mistake in aviation decarbonization is treating aircraft electrification as a universal substitute for liquid fuel. It is not.

Commercial jet fuel contains approximately 12,000 Wh/kg of energy. Lithium-ion batteries provide roughly 100–265 Wh/kg at the cell level. The comparison is not favorable even before accounting for battery-pack structure, thermal management, power electronics, reserve requirements, and the mass penalty that remains throughout the flight.

Jet fuel also becomes lighter as it is consumed. A battery does not. That affects aircraft range, payload, and operating economics. For short regional routes, hybrid or electric propulsion may eventually become technically relevant. Long-haul aviation is a different engineering category. The energy-density deficit is too large for direct battery substitution to solve the problem within the relevant planning horizon.

This is why synthetic kerosene remains strategically important. It is a drop-in fuel. Existing aircraft, airport storage systems, fueling equipment, and much of the distribution network can continue operating with limited modification, subject to fuel specifications and blending rules.

That compatibility has commercial value. It also creates a dangerous assumption: because e-kerosene fits the existing aircraft system, it must therefore be easy to scale. The fuel molecule is familiar. The upstream production chain is not.

A PtL facility generally needs to perform several energy-intensive operations:

1. Generate renewable hydrogen. Electrolyzers split water into hydrogen and oxygen. Their output depends on electricity availability, operating hours, efficiency, and the quality of the power supply.

2. Secure concentrated or atmospheric carbon dioxide. The carbon becomes part of the hydrocarbon molecule. It must be captured, purified, transported, and supplied at consistent pressure and volume.

3. Synthesize hydrocarbons. Hydrogen and carbon monoxide or carbon dioxide are converted into longer-chain hydrocarbons through processes such as Fischer–Tropsch synthesis.

4. Upgrade and refine the product. The resulting hydrocarbon mixture must be processed into aviation-grade kerosene with the required physical and chemical properties.

5. Move the fuel into the aviation system. Storage, blending, certification, airport delivery, and offtake contracts are not secondary details. They determine whether production capacity becomes usable supply.

The energy chain is therefore much longer than the label “renewable fuel” suggests. Electricity is converted into hydrogen, hydrogen into synthesis gas or hydrocarbons, and hydrocarbons into a specification-grade aviation product. Every conversion adds capex and efficiency losses.

E-kerosene is not limited by the availability of a fuel molecule. It is limited by the amount of clean energy and industrial equipment required to manufacture that molecule.

The central question is not whether PtL works in a reactor. It does. The question is whether the full chain can deliver enough fuel at a cost airlines can absorb without destroying route economics.

From project announcements to physical capacity

The project pipeline is often presented as evidence that e-kerosene is scaling. That interpretation is premature.

More than 40 large-scale e-kerosene projects have been proposed in Europe. By mid-2025, virtually none had reached a Final Investment Decision or entered full construction. A proposal is not capacity. A memorandum of understanding is not a plant. An announced production target is not an aviation fuel supply contract.

Final Investment Decision is the dividing line between policy ambition and industrial execution. Before FID, developers still need to resolve several linked risks:

• long-term access to renewable electricity at a predictable price;
• electrolyzer procurement and performance guarantees;
• reliable carbon dioxide supply;
• water availability and treatment;
• construction costs and schedule;
• permitting and grid connection;
• fuel certification and downstream logistics;
• binding airline offtake;
• debt financing and revenue support.

Each risk can be manageable in isolation. The problem is correlation. If electricity prices rise, hydrogen costs rise. If the electrolyzer operates fewer hours, fixed capital is spread over less output. If carbon capture underperforms, the synthesis unit loses feedstock. If airlines will not sign firm offtake agreements, lenders hesitate. If policy support changes, the entire financing model can fail.

The result is a project category with high technical confidence but low commercial certainty.

The scale problem inside a single plant

E-kerosene facilities are not simply refineries with a different input. They are integrated power-and-chemical plants. Their economics depend on utilization across multiple assets, not just the final synthesis unit.

A plant with large electrolyzer capacity needs electricity when the grid or renewable generators can provide it. Operating only during periods of low-cost renewable output may reduce power expenditure but increase the amount of equipment required to maintain annual production. Operating more consistently improves asset utilization but may require firmed power, storage, grid purchases, or a larger dedicated generation portfolio.

The project must also manage the mismatch between electricity production and fuel demand. Wind and solar generation are variable. Airlines require fuel continuously. That does not mean every PtL facility must operate as a fully isolated system, but it does mean the power architecture must be designed around annual fuel output rather than installed renewable capacity alone.

This is where capacity figures can mislead. A project may announce a gigawatt-scale renewable portfolio, but that number does not directly describe the volume of aviation fuel delivered. The relevant metrics are annual electricity consumption, electrolyzer utilization, hydrogen yield, carbon conversion, synthesis efficiency, product recovery, and final fuel output.

Without those figures, a production announcement is closer to a headline than an investment case.

The economics of Power-to-Liquid synthetic fuel

The power-to-liquid SAF cost structure is dominated by electricity, hydrogen production, carbon capture, and capital intensity. Feedstock is not the primary issue in the same way it is for biofuels. PtL uses carbon dioxide as a carbon source, but the process still requires a substantial and reliable supply of captured carbon.

Direct air capture is especially demanding because atmospheric carbon dioxide is dilute. The technology avoids dependence on a specific industrial emitter, but it requires additional energy and equipment. That flexibility comes with a cost.

Projected production costs for e-kerosene made with carbon dioxide from direct air capture are expected to decline from approximately $104–$124 per MWh in 2030 to $60–$69 per MWh in 2050. The projected decline is significant. It is not the same as cost parity with fossil jet fuel.

Those figures also need to be interpreted carefully. A production-cost estimate is not necessarily the final price paid by an airline. It may exclude or treat differently the cost of transport, blending, storage, certification, financing, policy compliance, and the risk premium attached to a first-of-a-kind facility.

The cost trajectory depends on learning rates that are not yet guaranteed. Lower costs would require several improvements at once:

• cheaper renewable electricity;
• more efficient electrolyzers;
• longer electrolyzer operating life;
• lower-cost hydrogen storage;
• improved carbon capture performance;
• larger and more standardized synthesis units;
• lower financing costs;
• better integration between power generation and fuel production;
• stable regulation that supports long-term offtake.

This is a familiar pattern in clean technology. The cost of one component can decline while the overall system remains expensive because another component becomes the bottleneck.

E-kerosene versus conventional SAF pathways

E-kerosene competes with other SAF routes for policy support, capital, renewable power, and airline contracts. The comparison is not simply technological. It is a question of supply ceilings and system constraints.

Neither pathway removes the underlying difficulty of aviation decarbonization. Biomass-based fuels face a physical ceiling. PtL faces a power and infrastructure ceiling. The practical aviation fuel mix will likely depend on both, alongside demand management and operational efficiency.

The carbon footprint of synthetic kerosene is also conditional. It is not automatically low-carbon because the carbon dioxide was captured. If the electricity is fossil-heavy, or if the hydrogen is not produced with genuinely low-emission power, the climate benefit can narrow sharply. The upstream system determines the result.

That makes accounting more demanding than a simple fuel-label comparison. A credible assessment must follow electricity sourcing, hydrogen production, carbon capture, process heat, transport, and any credits or penalties applied under the relevant regulatory system.

The climate performance of synthetic kerosene is an attribute of its power system, not a property of the word synthetic.

Regulation creates demand. It does not build the plants.

European regulation is beginning to create a market for synthetic aviation fuel. Under the EU ReFuelEU Aviation framework, minimum blending quotas for synthetic e-fuels start at 0.7% in 2030 and rise progressively to 35% by 2050.

That schedule matters. It gives airlines, fuel suppliers, and project developers a long-term demand signal. It also exposes the gap between mandated consumption and available production. The first quota is modest relative to total aviation fuel demand, but even a small percentage requires new industrial capacity because the current baseline is so low.

Regulation can support bankability through guaranteed demand, penalties for non-compliance, and a clearer price signal for low-carbon fuel. It cannot solve shortages of renewable power, electrolyzers, carbon dioxide, skilled labor, transmission capacity, or construction finance.

There is a recurrent policy error here: treating a mandate as if it were a supply chain. A regulation can require airlines to purchase a fuel. It cannot guarantee that the fuel will be produced at the required cost or in the required geography.

The risk is a compliance market with high prices and limited physical supply. Airlines may meet obligations through a combination of scarce fuel, certificates, exemptions, or other mechanisms, depending on the final rules. None of those mechanisms changes the engineering requirement for actual molecules if the objective is to replace fossil fuel rather than reclassify emissions.

The 500 million tonne requirement

IATA estimates that airlines will need approximately 500 million tonnes of SAF annually by 2050 to achieve net-zero carbon emissions. That is not a minor extension of today’s market. It is a new global fuel industry.

PtL is expected to bridge the gap beyond what sustainable biomass can supply. The implication is straightforward: e-kerosene must become a major industrial product, not a premium niche fuel used for demonstrations and corporate claims.

The challenge is visible in the current penetration rate. SAF represented only 0.53% of global jet fuel usage in 2024. Moving from that level to a system capable of delivering hundreds of millions of tonnes per year requires sustained investment across decades.

The bottleneck is not only production volume. Aviation fuel must meet strict specifications, and aircraft operators require dependable delivery. A fuel that exists in a laboratory or at a demonstration plant does not reduce fossil jet consumption unless it is delivered through an approved commercial supply chain.

That supply chain must also compete with other sectors for clean electricity. Green hydrogen is being proposed for steel, chemicals, shipping fuels, seasonal storage, and industrial heat. Direct air capture may require additional electricity and heat. E-kerosene cannot be assessed in isolation from those competing claims.

Resource competition: hydrogen, carbon and renewable power

The phrase “abundant renewable energy” is often used as if abundance were a local and permanent condition. It is not. The relevant question is where the electricity is generated, when it is available, how it reaches the plant, and what other industrial demand has priority.

Hydrogen is the first major pressure point. Electrolysis requires substantial electricity, and the resulting hydrogen must be compressed, stored, transported, or consumed close to the synthesis unit. A PtL project therefore needs more than renewable generation. It needs an operating model that keeps high-value equipment productive without undermining the emissions profile of the fuel.

Carbon dioxide is the second pressure point. E-kerosene requires carbon, but not all carbon sources are equivalent. Industrial point sources may provide concentrated CO₂ at lower cost than direct air capture, but their long-term role raises questions about source sustainability and the continued operation of emitting facilities. Direct air capture offers a more durable carbon accounting pathway, but current costs and energy requirements remain significant.

Water and land are additional constraints, although their importance varies by project location. Electrolysis requires purified water. Renewable generation requires land, transmission, or both. A project in a resource-rich region may produce fuel cheaply but face transport and certification issues. A project near European demand may reduce logistics costs but encounter expensive electricity, grid congestion, and permitting delays.

The optimal location is therefore not determined by the cheapest renewable power alone. Developers must balance:

• power price and annual availability;
• grid access and transmission capacity;
• water supply;
• carbon dioxide sourcing;
• hydrogen storage;
• proximity to refineries and airports;
• local permitting conditions;
• access to project finance;
• the credibility of airline offtake.

This is a systems problem. Improving one input does not guarantee a viable plant if the other inputs remain unstable.

What scale-up would actually require

A serious e-kerosene deployment strategy needs more than a list of proposed facilities. It needs evidence that the full industrial chain is moving toward execution.

The strongest signals are:

1. A Final Investment Decision. This indicates that technical studies, financing, permitting, and commercial contracts have reached a level acceptable to the project sponsors and lenders.

2. Firm electricity arrangements. Installed renewable capacity is not enough. The project needs a credible supply structure, including the treatment of intermittency and grid power.

3. A defined carbon pathway. Developers must identify whether the carbon comes from industrial capture, biogenic sources, or direct air capture, and how that source affects lifecycle emissions.

4. Technology guarantees. Electrolyzers, synthesis units, carbon capture systems, and upgrading equipment need performance assumptions that can withstand financial scrutiny.

5. Binding offtake. Airline interest is useful. Contracted demand is more useful. Financing depends on revenue visibility.

6. Construction progress. Procurement, site preparation, permitting, and equipment delivery reveal more than a public production target.

7. Lifecycle accounting. The project should demonstrate that the electricity and carbon inputs support the claimed emissions reduction rather than merely shifting emissions upstream.

These are not bureaucratic hurdles. They are the mechanisms that distinguish a fuel plant from a concept.

Commercial viability will be decided by execution

E-kerosene has a defensible role in aviation because the long-haul aircraft problem is fundamentally an energy-density problem. Batteries cannot currently match liquid jet fuel on a mass basis. Sustainable biomass is unlikely to supply the full future fuel requirement. PtL therefore remains one of the few pathways that could provide a scalable, drop-in liquid fuel without relying entirely on limited biological feedstocks.

That does not make it cheap, imminent, or automatically sustainable.

The economics will improve if renewable electricity, electrolyzers, carbon capture, and synthesis equipment become cheaper and more standardized. Regulation can create demand. Airline offtake can support financing. Industrial clustering can reduce infrastructure costs. But none of these factors removes the need for large quantities of clean power and a coordinated supply chain.

The near-term assessment is sober. E-kerosene is technically credible and strategically necessary, but its commercial base remains weak. The gap between announced projects and FID-stage construction is the clearest indicator. Until that gap closes, forecasts of mass availability are projections, not capacity.

For the aviation sector, the relevant metric is not the number of PtL headlines. It is the number of plants financed, built, certified, supplied with low-carbon inputs, and operated at a utilization rate that can support competitive fuel pricing. That is where e-kerosene scalability will be won or lost.