The genius of electric locomotives is that they do not need to carry fuel for propulsion. Instead, their “fuel” comes from overhead wires or a third rail. These overhead wires, called “catenary” carry electricity from a central power plant, a plant that is creating power from coal combustion, hydroelectric or nuclear fuel. These wire structures then make available the electricity which the locomotive needs for propulsion. In turn, the locomotive connects to the catenary with a box shaped frame called a “pantograph” which brings the electricity into the locomotive for use. Some locomotives have single arm pantographs.
In Switzerland, some dining cars had pantographs which allowed for the operation of electric stoves and ovens in their kitchens. Standing in the station, the diner would be connected to the electric grid; once underway, the pantograph would lowered as the car’s generator would begin to supply the needed power. The Swiss Railways also had some steam locomotives that used electricity to heat the water necessary for propulsion.
Electric locomotives don’t care what fuel they use. Hydro-electric, nuclear, coal, anything that produces electricity will do. The infrastructure for electric locomotives costs more than the average railroad, but there are substantial offsets. In the early days, electrification was the way around the smoke of steam locomotives. Now, the advantage of electric traction is efficiency, too.
Until command control entered the model railroad market, electric locomotives using catenary was an easy way to add a second locomotive to a model railroad. Now, of course, command control makes that an archaic memory.