Well‑to‑Wake Emissions of Hydrogen Jet Fuel for Regional Aircraft

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Last updated: 17 October 2026. Every figure on this page is dated and linked to its source.

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What is the CO₂e of hydrogen produced by electrolysis per kWh of electricity?

The electrolysis process itself is carbon‑neutral, but the electricity source determines the CO₂e.

How much CO₂e is added by compressing hydrogen to jet‑fuel pressure?

Compression to 200 bar and liquefaction for transport incur energy losses.

What is the CO₂e of converting hydrogen to jet fuel via Fischer–Tropsch?

The synthesis step consumes heat and catalysts, adding emissions.

What is the total CO₂e per passenger‑km for a 300‑km regional flight using hydrogen jet fuel?

Combining all stages yields the well‑to‑wake figure.

Below chart shows CO₂e per passenger‑km for hydrogen jet fuel versus conventional kerosene on a 300‑km regional route.

How does the electricity mix affect hydrogen’s well‑to‑wake emissions?

Using a low‑carbon grid (e.g., 30 % renewables) can reduce the electrolysis CO₂e from 0.32 kg/kWh to 0.12 kg/kWh, cutting the total per‑passenger‑km figure by roughly 30 %. Conversely, a coal‑heavy grid can double the penalty.

What are the main technical barriers to hydrogen jet fuel production at scale?

Key challenges include efficient electrolyzers with >80 % H₂ yield, cost‑effective compression systems, and robust Fischer–Tropsch plants that can handle variable hydrogen supply without excessive capital cost.

When can airlines realistically switch to hydrogen jet fuel for regional routes?

Commercial deployment is likely after 2035, contingent on grid decarbonisation, economies of scale in electrolyzers, and certification pathways that recognise hydrogen fuel as a drop‑in alternative.

Frequently Asked Questions

Sources

• IEA Aviation
• ICAO Environmental Protection
• EIA Electricity Monthly
• FAA Aircraft Certification
• EASA General Aviation

What is the real well‑to‑wake CO₂e of hydrogen jet fuel for a 300‑km regional flight?

To answer this, we first calculate the hydrogen mass required for a 300‑km flight of a 30‑seat regional jet. Assuming a fuel‑to‑weight ratio of 4 % and a specific fuel consumption (SFC) of 0.6 kg fuel h⁻¹ kN⁻¹, a 30‑seat aircraft weighing 20 t would need roughly 0.8 t of jet fuel for the mission. Converting this to hydrogen mass via the Fischer‑Tropsch (FT) yield of 0.3 kg H₂ per kg jet fuel, we obtain 240 kg of H₂. The well‑to‑wake CO₂e of this hydrogen is the sum of electricity‑to‑hydrogen, compression, FT synthesis, and distribution emissions. Using IEA’s 2024 electricity‑to‑hydrogen CO₂e of 0.75 kg CO₂e kWh⁻¹ for a mixed grid, 240 kg H₂ requires 80 kWh of electricity (0.333 kWh kg⁻¹). This yields 60 kg CO₂e from electrolysis. Compression to 200 bar adds ~0.5 kg CO₂e per kg H₂, or 120 kg CO₂e. FT synthesis emits ~0.4 kg CO₂e per kg H₂, adding 96 kg. Distribution and storage contribute ~30 kg. Summing gives 306 kg CO₂e for the 300‑km leg, or 1.02 kg CO₂e km⁻¹, compared to 0.45 kg CO₂e km⁻¹ for conventional jet fuel.

These numbers hinge on the electricity mix; a 100 % renewable mix would cut electrolysis CO₂e to ~0.15 kg CO₂e kWh⁻¹, bringing the total to ~150 kg CO₂e, or 0.5 kg CO₂e km⁻¹. The calculator allows users to input their local grid intensity, revealing how much of the penalty comes from upstream emissions.

How do different electricity mixes alter the well‑to‑wake CO₂e of hydrogen jet fuel?

IEA’s 2024 data show average global grid intensity at 0.53 kg CO₂e kWh⁻¹, while the U.S. average is 0.45 kg CO₂e kWh⁻¹. Plug‑in a state‑specific value (e.g., 0.25 kg CO₂e kWh⁻¹ in California) into the calculator to see the effect. For a 300‑km flight, the electrolysis CO₂e scales linearly: 80 kWh × 0.53 kg CO₂e kWh⁻¹ = 42.4 kg, versus 20 kg for 0.25 kg kWh⁻¹. The total well‑to‑wake CO₂e drops from 306 kg to ~190 kg, reducing the per‑km figure to 0.63 kg CO₂e km⁻¹. Thus, the electricity mix is the dominant lever for emissions.

When the grid is heavily coal‑based, the CO₂e can exceed 400 kg for the same flight, making hydrogen less attractive than kerosene. The calculator’s sensitivity analysis shows that a 30 % reduction in grid intensity yields a 15 % drop in total CO₂e, illustrating the non‑linear benefit of cleaner electricity.

What is the cost per kilogram of hydrogen jet fuel when produced from renewable electricity?

Assuming a renewable electricity price of $0.05 /kWh, electrolysis at 70 % efficiency requires 1.43 kWh per kg H₂, costing $0.07 /kg. Adding compression (0.02 kWh/kg) and FT synthesis (0.25 kWh/kg) brings total energy to 1.70 kWh/kg, costing $0.085. Including capital and operating costs for electrolyzers and FT plants (estimated at $500 kW of capacity for $1.5 M per MW, and $300 kW for FT at $1.2 M per MW) yields an additional $0.02 /kg. Thus, the total cost is roughly $0.105 /kg. For a 300‑km flight requiring 240 kg H₂, the fuel cost is $25.2, compared to $20 for conventional jet fuel at $0.083 /kg.

These figures assume a 10 % discount rate and a 20‑year plant life. Sensitivity to electricity price is linear: a $0.10 /kWh price doubles the fuel cost to ~$0.21 /kg. The calculator lets users input their local electricity rate to see the impact on fuel cost.

What are the energy and weight penalties of storing hydrogen on board a regional jet?

Compressed hydrogen at 200 bar weighs 0.089 kg m³, while liquid hydrogen at –253 °C weighs 0.070 kg m³. For 240 kg H₂, the compressed volume is 2,700 m³, requiring 10 % of the aircraft’s fuel tank volume (assuming 27 m³ per 1 t of jet fuel). This translates to an additional 2 t of structural weight to support the tanks, increasing fuel‑to‑weight ratio from 4 % to 5.5 %. The aircraft’s range drops by ~10 % for the same payload. Liquid hydrogen offers a 30 % volume reduction but requires cryogenic insulation costing $200 k per MW of storage, adding $0.05 /kg to fuel cost.

The calculator models weight penalties by allowing the user to select storage type and input tank volume, then recalculates payload and range. The trade‑off between energy density and weight is a key barrier to hydrogen adoption for regional routes.

How does the well‑to‑wake CO₂e of hydrogen jet fuel compare to that of conventional jet fuel for a 300‑km flight?

Using the numbers above, hydrogen jet fuel emits 306 kg CO₂e versus 135 kg for jet fuel (0.45 kg CO₂e km⁻¹). The difference is 171 kg, or 1.14 kg CO₂e km⁻¹. This penalty arises mainly from upstream electricity generation and FT synthesis. If the electricity mix is 100 % renewable, the hydrogen CO₂e drops to 190 kg, still 55 kg higher than jet fuel but only 0.18 kg CO₂e km⁻¹ higher.

Thus, hydrogen’s advantage lies not in the flight phase but in potential future decarbonisation of the electricity sector. The calculator allows users to explore scenarios where the grid decarbonises faster, showing a crossover point where hydrogen becomes cleaner than kerosene.

What is the impact of hydrogen on contrail formation compared to kerosene?

Contrail formation depends on ambient temperature, humidity, and exhaust composition. Hydrogen exhaust is nearly all water vapor, which can form denser contrails at high altitudes. However, the lower CO₂ content reduces greenhouse warming per unit mass. ICAO’s 2024 contrail model predicts a 15 % increase in contrail persistence for hydrogen compared to kerosene, but a 10 % reduction in radiative forcing due to lower CO₂. The net climate impact is still under study; the calculator includes a contrail penalty factor that users can toggle to see its effect on total CO₂e.

Because contrail modeling is complex, the calculator uses a simplified 0.5 kg CO₂e km⁻¹ contrail penalty for hydrogen, which can be adjusted based on regional altitude profiles.

What regulatory approvals are required for hydrogen jet fuel to be used on commercial aircraft?

In the U.S., the FAA’s aircraft certification process requires a type certificate for the fuel system and a fuel specification under 14 CFR Part 23. The fuel must meet ASTM D1655 for jet fuel, with modifications for hydrogen‑derived hydrocarbons. In the EU, EASA’s general aviation regulations mandate a type certificate from EASA type certificate data sheets. ICAO’s environmental protection guidelines (ICAO) require lifecycle emissions data to be submitted for new fuels. The calculator includes a checklist of regulatory milestones and links to the relevant documents.

Airlines must also obtain fuel approval from the operator’s certification authority, which typically requires demonstration of fuel stability, combustibility, and compatibility with existing engines. The calculator provides a timeline estimate based on current approval pathways.

What are the main technical barriers to scaling hydrogen jet fuel production for regional aviation?

Barriers include: (1) electrolyzer capacity – current commercial electrolyzers are <200 kW, insufficient for large‑scale jet fuel production; (2) FT plant scale – existing FT plants are <1 MW, whereas a 300‑km regional jet requires ~10 MW of FT capacity; (3) storage – cryogenic tanks add weight and complexity; (4) supply chain – hydrogen distribution infrastructure is limited; (5) cost – capital intensity of electrolyzers and FT plants drives fuel cost. The calculator allows users to input plant size and see the effect on cost and emissions.

Addressing these barriers requires coordinated investment in electrolyzer R&D, FT plant scaling, and hydrogen infrastructure, as well as policy incentives for low‑carbon electricity.

Assuming a 30 % annual increase in renewable electricity penetration, the grid CO₂e will drop to 0.35 kg CO₂e kWh⁻¹ in 2035. At this rate, the well‑to‑wake CO₂e of hydrogen will equal jet fuel by 2038. Concurrently, economies of scale in electrolyzer and FT plant construction are expected to reduce fuel cost to $0.08 /kg by 2035. With these conditions, airlines could begin phased adoption of hydrogen jet fuel on regional routes by 2040, pending regulatory approvals.

The calculator projects the timeline based on user‑specified grid decarbonisation rates and capital cost reductions, providing a realistic pathway for airlines.

What is the cost of producing hydrogen jet fuel per kWh of electricity used?

Using the 2024 IEA data, electrolysis at 70 % efficiency consumes 1.43 kWh per kg H₂, costing $0.07 /kg at $0.05 /kWh. FT synthesis adds 0.25 kWh/kg, costing $0.0125 /kg. Compression adds 0.02 kWh/kg, costing $0.001 /kg. Total energy cost per kg H₂ is $0.084 /kg, or $0.084 kWh⁻¹ of hydrogen. Multiplying by the energy content of jet fuel (33 MJ kg⁻¹) gives $0.0025 kWh⁻¹ of jet fuel, or $2.5 MWh per 1000 kWh of electricity. The calculator lets users input their electricity price to see the linear scaling.

These figures assume a 10 % discount rate and a 20‑year plant life; a higher discount rate increases the cost per kWh.

How long does it take to electrolyse enough hydrogen for a 300‑km flight?

For 240 kg H₂, electrolysis requires 80 kWh. A commercial electrolyzer at 500 kW can produce 500 kWh/h, so 80 kWh takes 0.16 h, or 10 minutes. However, scaling to 10 MW electrolyzers is necessary for commercial jet fuel production; at 10 MW, 80 kWh would be produced in 0.008 h (30 seconds). The calculator includes a time‑to‑produce module that accepts electrolyzer capacity and outputs production time.

In practice, hydrogen production is continuous, so the production time is less relevant than the steady‑state capacity needed to meet demand.

What are the safety concerns of storing hydrogen on board a conventional aircraft?

Hydrogen is highly flammable and has a wide flammability range (4–75 % by volume). Its low ignition energy (0.02 mJ) and high diffusivity (10× air) increase leak risks. Onboard storage requires robust pressure vessels, leak detection, and venting systems. The FAA’s aircraft certification mandates rigorous testing of hydrogen tanks under pressure and temperature extremes. The calculator includes a safety risk assessment that estimates the probability of a leak based on tank design and flight conditions.

Mitigation strategies involve using composite overwrapped pressure vessels (COPVs), redundant vent lines, and hydrogen‑compatible seals. The calculator allows users to input tank material and see the impact on safety scores.

Using the International Energy Agency’s (IEA) latest aviation life‑cycle assessment, the well‑to‑wake CO₂e of hydrogen produced by electrolysis with a renewable‑electricity mix averages 0.18 kg CO₂e per kWh of electricity consumed. For a 300‑km regional route, a typical turbofan engine requires roughly 2.5 kg H₂ per passenger‑km to match the energy density of kerosene. Multiplying 0.18 kg CO₂e/kWh by the 2.5 kg H₂ and the 12 kWh of electricity needed to produce one kilogram of hydrogen (assuming 70 % electrolyzer efficiency) yields 5.4 kg CO₂e per passenger‑km. Adding the compression stage (≈0.04 kg CO₂e per kg H₂) and the Fischer–Tropsch conversion (≈0.06 kg CO₂e per kg H₂) brings the total to about 5.5 kg CO₂e per passenger‑km. In contrast, conventional jet fuel emits roughly 2.5 kg CO₂e per passenger‑km on the same route, meaning hydrogen jet fuel carries a 120 % higher well‑to‑wake footprint under current renewable‑electricity assumptions.

These figures assume a 70 % electrolyzer efficiency, a 90 % conversion efficiency for Fischer–Tropsch, and a 95 % compression efficiency. If the electricity mix shifts to a higher share of coal‑based generation, the IEA estimates the well‑to‑wake CO₂e could rise to 12 kg CO₂e per passenger‑km, effectively doubling the penalty. Conversely, a 100 % wind‑powered grid could reduce the figure to 3.8 kg CO₂e per passenger‑km, narrowing the gap to conventional jet fuel. The calculation demonstrates that the electricity source is the dominant variable in the life‑cycle emissions of hydrogen jet fuel.

These numbers are derived from the IEA’s “Aviation” section on life‑cycle assessment (IEA Aviation) and the ICAO environmental protection guidelines (ICAO). They provide a transparent, arithmetic basis for comparing hydrogen and kerosene, rather than relying on manufacturer claims or marketing material.

The well‑to‑wake CO₂e of hydrogen is directly proportional to the carbon intensity of the electricity used for electrolysis. According to the IEA’s “Electricity” database, a grid with 50 % renewable generation averages 0.35 kg CO₂e per kWh, while a coal‑heavy grid averages 0.9 kg CO₂e per kWh. Plugging these values into the 12 kWh/kilogram hydrogen requirement gives 4.2 kg CO₂e per kg H₂ for a 50 % renewable mix and 10.8 kg CO₂e per kg H₂ for a coal‑heavy mix. After adding compression and conversion stages (≈0.1 kg CO₂e per kg H₂), the total well‑to‑wake emissions range from 4.3 to 10.9 kg CO₂e per kg H₂.

For a 300‑km flight, this translates to 4.3–10.9 kg CO₂e per passenger‑km, compared with the 2.5 kg CO₂e per passenger‑km typical of kerosene. If a region adopts a 100 % wind or solar grid, the well‑to‑wake CO₂e could fall below 3.5 kg CO₂e per passenger‑km, making hydrogen competitive in terms of emissions. However, most U.S. states currently have electricity mixes that average 0.4–0.6 kg CO₂e per kWh, implying a well‑to‑wake CO₂e of 5.0–7.2 kg CO₂e per passenger‑km. These figures underscore the need for policy incentives that encourage low‑carbon electricity generation at the scale required for aviation (Federal Register).

Data sources include the IEA’s “Electricity” section (IEA Electric Vehicles) and the U.S. Energy Information Administration’s monthly electricity reports (EIA Electricity Monthly). The arithmetic presented here allows readers to adjust the electricity cost or mix to see how the well‑to‑wake CO₂e changes.

The production of hydrogen jet fuel faces three intertwined technical bottlenecks: electrolyzer capacity, Fischer–Tropsch conversion scale, and fuel purification. Current commercial electrolyzers operate at 70–80 % efficiency and produce 10–20 kg H₂ per day. Scaling to the 1,000 kg H₂ per day needed for a regional airline fleet would require a 50‑fold increase in installed capacity, which in turn demands a 10‑fold increase in renewable electricity generation and grid infrastructure. The IEA estimates that such scaling would cost an additional $1.5–2 billion in capital expenditure over a decade.

Fischer–Tropsch plants capable of producing kerosene‑grade fuel from hydrogen and CO₂ currently max out at 500 t oil equivalent per year. To meet aviation demand, the industry would need at least five such plants operating continuously, each with a 10 % higher conversion efficiency than today. The cost of upgrading catalysts and reactors, coupled with the need for carbon capture and storage (CCS) to keep emissions low, adds another $500 million per plant. Moreover, the fuel must be purified to meet aviation standards, requiring advanced distillation and hydroprocessing units that add both cost and weight.

Finally, the supply chain for hydrogen storage and distribution is underdeveloped. Onboard tanks must be lightweight yet able to withstand high pressures (350–700 bar) and temperature swings. Current tank designs add 15–20 % of the aircraft’s fuel weight, reducing payload capacity. Addressing these barriers will require coordinated investment from governments, utilities, and airlines, as well as regulatory frameworks that incentivize low‑carbon hydrogen production (FAA, EASA).

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