I'm not against using Hydrogen but the problem is always what are they producing Hydrogen with and how is it more efficient energetically and emission wise?
Even if it is just Blue hydrogen being burnt here, the splitter plants can have some carbon capture in it which would be impossible to install on a moving train (beats diesel and also direct LNG burning).
That said, with trains there's no real argument against electrification. The wheels have been electrically driven for a few decades now. It's not like they need to come up with motors or work out batteries.
Liquid hydrogen takes up a lot more room than kerosene. The insulated liquid-hydrogen tank is quite a lot bigger than the kerosene tank -- maybe it is a whole other car -- but so what? Room on a train is cheap. What matters is weight. The tank is light, and the weight of LH2 needed to go the same distance is much less. The difference is weight that doesn't itself need to be transported.
Furthermore, the LH2 can be produced and banked on-site at the railyard, and during peak-production hours, so cheaply.
So, a win all around. Not as big a win as LH2-powered aircraft, but better, and much easier to retrofit.
Better gravimetric energy density doesn't make so much difference for a train, so its other advantages -- production on-site, zero emissions, carbon-neutral -- are more important.
At the trainyard, the LH2 would be banked in an underground tank where insulation is easy. It is not necessary to refrigerate it after it is liquified. It will gradually boil off, so you just make more anytime the level goes down, whether from boil-off or pumping out to a locomotive tank.
My expectation was that native electrical energy will be cheap enough that wasting some is better than complicating your system. Each tradeoff will be an engineering analysis. In this case it will all depend on how good your insulation is, which is of course better in an underground tank. Many old conventions will be overturned as the marginal cost of electrical power at peak times gets cheaper.
Both will be tried, so we will see.
Which adds three energy transformation steps (Electricity for H2O to H2 + compression, H2 + 02 to water and heat, water and heat to mechanical movement) as opposed to electricity to motor.
Hydrogen is a meme.
But hydrogen is not best compressed, but liquified. There might be some value in compressing it on the way to liquifaction. Liquifying hydrogen consumes some energy too.