There are three main types of fuels that have been used in rail transport throughout history. Following are the fuels:
A large internal combustion engine powered by diesel fuel generates electricity to power a series of electric motors that turn the wheels. Unlike a steam locomotive, diesel locomotives do not require a tender – their fuel is stored in a tank below the floor. Diesel locomotives are much simpler to operate than steam, and since they are controlled electrically, several of them can be linked together and controlled at the same time to pull longer trains.
In electric locomotives, the electricity to run their motors is picked up through a device on the roof called a pantograph, which contacts a wire suspended over the track. The electric locomotive is simple and easy to operate but the only major disadvantage is that they only operate where the overhead wire is installed.
A large boiler of water is heated by fire, the water boils and makes the high-pressure steam that is piped to a pair of cylinders near the front of the locomotive. The steam generated pushes the piston that turns the wheels and moves the train. Most steam locomotives pull a small car that carries water and fuel for the fire. The fire can be fueled by anything that burns, but it usually uses either coal or oil.