An energy systems model of large commercial liquid hydrogen aircraft in a low-carbon future

Liquid hydrogen (LH2) aircraft have the potential to achieve carbon neutrality. However, if the hydrogen is produced using electricity grids that utilise fossil fuel, they have a non-zero carbon dioxide (CO2) emission associated with their well-to-wing pathway. To assess the potential of LH2 in aviation decarbonisation, an energy systems comparison of large commercial LH2, liquified natural gas (LNG), conventional Jet-A and LH2 dual-fuel aircraft is presented. The performance of each aircraft is compared towards 2050, over which three system changes occur: (1) LH2 aircraft technology develops; (2) both world average and region-specific grid electricity, which is used to produce the hydrogen, decarbonises; and (3) the International Air Transportation Association (IATA) emissions targets, which are used to restrict the passenger-range performance of each aircraft, tighten. In 2050, the emissions of all aircraft are thus constrained to 0.063 kg-CO2/p-km, relative to 0.110 kg-CO2/p-km for the unconstrained Jet A fuelled Boeing 787-8. It is estimated that, in this year, an LH2 aircraft powered by fuel cells and sourcing world average electricity can travel 6000 km, 20% further than the conventional Jet A aircraft that is also constrained to meet the IATA targets, but not as far as the LNG aircraft. At its maximum range, the LH2 aircraft carries 84% of the Jet A passenger demand. Analysis using region-specific hydrogen indicates that LH2 aircraft can travel further than LNG aircraft in North America only, accounting for 17% of the global demand. 1.59 times the current aviation energy consumption is required if all conventional aircraft are replaced with LH2 designs. Under stricter emissions constraints than those outlined by the IATA, LH2 outperforms LNG in Europe and the Americas, accounting for 41% of the global demand. Also in these regions, the range, energy consumption and passenger capacity of LH2 aircraft can be improved upon by combining the advantages of LH2 with LNG in dual-fuel aircraft concepts. The use of LH2 is therefore advantageous within several prominent niches of a future, decarbonising aviation system.