Liquid hydrogen (LH2) could be the fuel of choice for flights up to 3,400 km as of 2035, accounting for 31-38% of all passenger flights, according to a performance analysis report from the International Council on Clean Transportation.
The study found that an LH2-powered turbofan aircraft, similar in design to the Airbus A320 (see photo below), could carry 165 passengers up to 3,400 km, while a smaller turboprop aircraft could carry 70 passengers up to 1,400 km. Together, these two aircraft could serve all short- to medium-haul flights, which account for about a third of all passenger air traffic.
Since liquid hydrogen — which must be stored at temperatures below minus 253°C — has a much lower energy density per volume than conventional jet fuel, this would significantly increase fuel costs.
“Carbon pricing would be needed to get green LH. to make2 cost competitive, with break even compared to Jet A [fuel] expected between $102 and $277/ton CO2equivalent in 2050, depending on geography,” the ICCT says.
“Given the industry-wide push towards non-biomass SAFs [sustainable aviation fuels], synthetic fuels such as e-kerosene [derived from green hydrogen and captured CO2] would probably be a better cost comparison for hydrogen than Jet A, especially from 2035. Our results suggest that green LH2 will be cheaper than e-kerosene on routes up to 3,400 km.”
The study states that blue LH2 would be the most expensive jet fuel, followed by e-kerosene, green LH2 and Jet A.
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However, it adds that the price advantage of green LH2 compared to e-kerosene – which would be chemically identical to Jet A fuel – “could be smaller or vice versa if one takes into account the cost of building hydrogen refueling infrastructure at airports. On the other hand, the cost of e-kerosene production could rise if the more energy-intensive DAC [direct air carbon capture] (rather than point source carbon capture) is required.”
The ICCT, a Washington DC-based nonprofit, says that even if blue hydrogen from natural gas had a 99.9% carbon capture rate, it would still result in about 40% of the CO2-equivalent (CO2e) from Jet A fuel — presumably due to methane emissions upstream (although this is not explained in the report).
“Using less optimistic assumptions for the blue hydrogen pathway would further reduce its benefits; for example, below average (63.71 g-CO2e/MJ), blue hydrogen would only reduce emissions by 14% compared to Jet A. Green LH2 and e-kerosene, on the other hand, have near-zero carbon intensities per RPK [revenue-passenger-kilometre].”
Airbus is the only large-scale aircraft manufacturer actively developing hydrogen-filled aircraft, unveiling three new H2 aircraft designs in 2020.
Its main rival, Boeing, is not convinced of the benefits of carbon-free fuel. Last month, Chris Raymond, Chief Sustainability Office, said: “Liquid hydrogen is probably the best way to use it as a fuel, but it requires large cooling systems and large storage systems. Hydrogen needs about four times the volume to get the same amount of energy, so you get a plane with more fuel tanks than passenger capacity – and that compromises overall efficiency.”