Even if the train’s electric power comes from coal, not carrying fuel with you is a win from an efficiency standpoint.

There are some military planes flying on biofuel, so ideally we’re not that far off.

https://www.energy.gov/eere/bioenergy/aviation-fuels

So I think that’s not really true. Even existing battery chemistry could do 1000km per stop (although it still needs certification for aircraft) and at comparable speed as HSR. That’s much longer than the California HSR project that was canceled, plus you just need a recharge (or swap) to continue on your way. With further efficiency improvements and battery chemistries in development right now like Li-S, we could potentially do 4000km flights (enough to reach Hawaii... and anywhere else using multiple hops, as Boom is planning). And shorter flights at higher than HSR speeds.

HSR has its own unsolved problems. Like not being able to work over deep ocean... and insane infrastructure costs.