As you well know, trains are some amazing pieces of machineries, they have revolutionized the way we travel and transport freight. Throughout the years, trains used to run on few types of fuel, and yes at one point trains ran on gas.
Which trains run on gas? Are there any today?
One of the most well known gas powered passenger train was McKeen Railmotor. Using a 6-cylinder engine the self propelled railcar outputs around 100 horsepower, carrying between 69 and 75 people (seating capacity).
Another self propelled railcar was the Bugatti ZZY 24408, using 4 gas engines the train was one of the “Autorail Rapide” express railcar in France.
A few other examples include The Panama Railroad, "Yellow Peril"; The Panama Railroad Gasoline 6 and 6A; Motor Car No. 1.
There are no trains running on gas, gas powered or propelled in use today.
Why is that? Why are trains that run on gas not used anymore?
As history, economics and physics tells us, they are not reliable, cost way more to operate and there are better alternatives.
On average the gas powered trains cost double per mile to operate, compared to the steam locomotives, where even the steam locomotives are way less efficient and cheap to operate than diesel locomotives.
Besides that, the gas/petrol even diesel train engines can’t output the tremendous torque and power needed to move a train, not for today’s standards.
Note: Today’s trains are diesel-electric not diesel there is a huge difference) diesel is used to power the main alternator, which produces electricity for the traction motors, putting the train on move.
What do trains used to run on?
Trains used to run on few types of fuel, steam powered (coal), gas/petroleum, diesel, diesel electric.
Steam engines (coal) were broadly used throughout the world, many great locomotives were built in the Steam era, revolutionizing the whole industry. In the same time diesel locomotives were improving, however until 1925 there was a small number of diesel trains in the United States.
After World War II, while the economy started to improve, diesel locomotives have witnessed a widespread adoption in many countries. They offered better performance and lower costs of operation than steam locomotives.
What do trains run on?
Starting with the 1970s, the diesel-electric trains started to dominate. Today these types of locomotives are used not only by freight railroads but by passenger trains as well.
As an example of efficiency, CSX trains can move 1 ton of freight nearly 500 miles using just one gallon of fuel. According to the same source, a train is 3.7 times more efficient at hauling freight than a truck.
Besides, the diesel-electric is extremely powerful, outputting thousands of horsepower, requiring a low maintenance, they’re quite small (compared with steam).
For a final answer to the question, assuming you are interested in today’s trains, 99% of them run on diesel-electric or electric power, with the rest 1% being steam locomotives used for entertainment purposes, vacations, etc.
What do AmTrak trains run on?
AmTrak’s rolling stock includes over 240 locomotives, out of which most of them are diesel-electric and some fully electric.
They operate over 180 GE P42DC diesel-electric locomotives and over 60 Siemens ACS-64 which are fully electric.