Comment by csours

> Would this be less efficient than battery powered EVs?

Measured in terms of mass * distance, trains with steel wheels will beat anything with rubber pneumatic tires.

Part of the magic of hybrid trains is that you can have multiple generation units that can be turned on or off as needed.

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Efficiency is just one consideration for a power plant.

Historically, reliability has been more important than efficiency, especially for industrial applications like locomotives. In other words, locomotives are probably not as efficient as they could be. For instance, you could use a lower viscosity engine oil for lubrication, but that would reduce reliability as engines fail due to friction.