How do you operate a train without an external electricity supply?

The great majority of trains operate using an electricity supply that is external to the vehicle.
When the rail network is not electrified, the train must use its own energy for propulsion. Several solutions are possible:

How do you operate a train without an external electricity supply?

To operate without an external power supply, the train must transport its own energy for propulsion. Traditionally, this was carried along in the form of coal and water (steam traction) or diesel (diesel traction). Thanks to recent progress made, autonomous electric traction (based on the principle of storing electricity in a battery, providing electrical energy along the way) and hydrogen traction (hydrogen is stored in tanks to produce electricity) have seen the light of day.

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