Or non-electrified railways. A modern "diesel" engine is actually diesel-electrical anyways, since curiously diesel->electric->movement is more efficient than straight diesel->movement. For a hydrogen-electrical engine you could presumably stick one or two special tanker cars behind it with the necessary tech to keep it cool. The engine could even be dual-mode and use electrification where available (like this one already does for diesel: https://en.wikipedia.org/wiki/Bombardier_ALP-45DP )
For comparison, an ES44AC [https://en.wikipedia.org/wiki/GE_Evolution_Series] carries 18900l of diesel (weighing 15.7 tons), which at 38.6 MJ/l rounds to 730GJ of energy. Hydrogen seems to have a specific energy of 120-142 MJ/kg, using the conservative 120 that's about 6.1 tons of hydrogen, but now for the volume... https://www.energy.gov/eere/fuelcells/hydrogen-storage lists "0.03kg/l" as a "system target"... so 6.1 tons is 203,333l. That's 2 conventional tank cars (but those don't have any cooling or pressurization systems.)
(Of course this assumes the efficiency of diesel->electrical and hydrogen->electrical to be similar, which is not the case.)
For comparison, an ES44AC [https://en.wikipedia.org/wiki/GE_Evolution_Series] carries 18900l of diesel (weighing 15.7 tons), which at 38.6 MJ/l rounds to 730GJ of energy. Hydrogen seems to have a specific energy of 120-142 MJ/kg, using the conservative 120 that's about 6.1 tons of hydrogen, but now for the volume... https://www.energy.gov/eere/fuelcells/hydrogen-storage lists "0.03kg/l" as a "system target"... so 6.1 tons is 203,333l. That's 2 conventional tank cars (but those don't have any cooling or pressurization systems.)
(Of course this assumes the efficiency of diesel->electrical and hydrogen->electrical to be similar, which is not the case.)
P.S.: https://en.wikipedia.org/wiki/Hydrail & https://www.bbc.com/future/article/20200227-how-hydrogen-pow...