Liquid hydrogen (LH2) could be the preferred fuel for flights of up to 3,400km from 2035, accounting for 31-38% of all passenger aviation journeys, according to a performance analysis report by the International Council on Clean Transportation.
The study found that an LH2-powered turbofan aircraft, similar in design to the Airbus A320 (see picture below), could transport 165 passengers up to 3,400km, while a smaller turboprop plane could take 70 passengers up to 1,400km. Together, these two aircraft could serve all short to medium-range flights, which account for about a third of all passenger aviation traffic.
As liquid hydrogen — which needs to be stored at temperatures below minus 253°C — has a much lower energy density by volume than conventional jet fuel, it would increase fuel costs considerably.
“Carbon pricing would be needed to make green LH2 cost-competitive, with breakeven compared to Jet A [fuel] expected at between $102 and $277/tonne CO2-equivalent in 2050, depending on geography,” the ICCT says.
“However, given the industry-wide push toward non-biomass SAFs [sustainable aviation fuels], synthetic fuels like e-kerosene [derived from green hydrogen and captured CO2] would likely be a better cost comparison for hydrogen than Jet A, especially from 2035 onwards. Our results suggest that green LH2 will be cheaper than e-kerosene on routes up to 3,400km.”
The study states that blue LH2 would be the most expensive aviation fuel, followed by e-kerosene, green LH2 and Jet A.
However, it adds that the price advantage of green LH2 over e-kerosene — which would be chemically identical to Jet A fuel — “could be smaller or reversed when accounting for the cost of building hydrogen refueling infrastructure at airports. On the other hand, the cost of e-kerosene production could increase if the more energy-intensive DAC [direct air carbon capture] (rather than point source carbon capture) is required.”
The ICCT, a Washington DC-based non-profit organisation, says that even if blue hydrogen derived from natural gas had a carbon capture rate of 99.9%, it would still result in about 40% of the CO2-equivalent (CO2e) of Jet A fuel — presumably due to upstream methane emissions (although this is not spelled out in the report).
“Using less optimistic assumptions for the blue hydrogen pathway would further degrade its benefits; for example, under the mean (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 airplane manufacturer actively pursuing the development of hydrogen-fulled aircraft, revealing three new H2 plane designs back in 2020.
Its main rival, Boeing, is not convinced of the zero-carbon fuel’s merits. Last month, its chief sustainability office, Chris Raymond, said: “Liquid hydrogen is probably the best way to use it as a fuel, but it requires big cooling systems and big storage systems. Hydrogen requires about four times the volume to get the same amount of energy, so you end up with a plane that is more fuel tanks than it is passenger capacity — and that risks the efficiency overall.”
