How many locomotives are there in operation throughout the world?

Question

I am trying to grasp the scale of fuel consumption by railways, I have read that modern locomotives burn some 160 gallons of fuel per hour. I wonder why they don't have small steam turbines running off of the exhaust gas heat, like ships use. The turbine could generate electricity, which would decrease the amount of fuel required to drive the wheels. Since modern locomotives use electric traction motors, there would be almost no change required to the basic system.

Answer 1

Thousands. To get an accurate picture you would have to buy or borrow a copy of 'Jane's All The World's Railways'.

Modern diesel locomotives now use leaner-burn engines which put out fewer emissions.

Answer 2

Elwood hit it when he said there's thousands -- UP alone uses over 5 000 and NS uses about that many.

Yes some of the older locomotives [gp 7's and the like] used 186 gallon per hour if it was just idling, and the same amount if the throttle was opened up full ["Run 8"].

Newer locomotives use less --  I even think they now calculate fuel usage in Miles per Gallons!