[pencilguin]

Power cables are an attractive theft target, many places.

An extra insulated car filled with lightweight LH2 would not appreciably increase the cost of operating a train.

Liquified ammonia under low pressure might be more practical, if safety worries don't dominate. We already move tanks of ammonia on trains. And much worse.

[bryanlarsen]

Liquid green hydrogen costs an order of magnitude more than electricity, and always will since it's created from electricity and uses electricity for liquification. It definitely will appreciably increase the cost of operating a train.

[pencilguin]

The weight of one extra car will increase the operating cost of a 100-car train by 1%, give or take a bit. Using cheap hydrogen instead of expensive kerosene may save much more than that. Moving light hydrogen instead of heavy kerosene may save more than that.

If the electricity could be delivered directly to the train, the energy used would be cheaper, but installing (and replacing "shrinkage" of) many thousands of miles of "third rail" would cost a lot.

The hydrogen is not yet cheaper than the kerosene, but costs on that side are falling fast.

[bryanlarsen]

You don't need thousands of miles of third rails or catenary wires. Just a ~mile every ~hundred, and a battery on the locomotive.

[pencilguin]

That is an interesting alternative.

You need a battery that tolerates many many cycles, and being charged at 100x its usual discharge rate. Maybe a molten CaSb battery, from Ambri.

I guess if all the cars can be wired to take in power, you just need a short stretch of 3rd rail at each charge point, say 60 m, not 1600. If each car has its own battery and drive motors, they don't need to be wired together. Relative charge rate goes to 10,000x, but the grid load stays the same.

[_hypx]

It's cheaper to just electrify the gaps. His views are fundamentally nonsensical and shows that he hadn't really thought about the problem. Hydrogen trains are for remote tracks, sometimes thousands of miles of unelectrified rail. If you can't justify ever electrifying those tracks, then hydrogen trains are the obvious answer.

[pencilguin]

Ammonia trains might be a better answer.