André Chapelon's correspondence
 

Extract of a letter to Mr. Tentesaux-Vernier (historian of French railways now deceased) in which Chapelon compares - on the joke mode but it remains a very interresting comparison however - the efficiencies of steam vs. electrical railroads

April the 3rd., 1957

.... Let's consider a 1 500 tons coal train making 200 kilometers, worked by a steam locomotive which will burn, let's s say 20 kilograms per kilometer or 4 000 kilograms during the journey; Let's take those 4 000 kilograms in the 1 500 tons, so 1 496 tons will reach the destination, the resulting efficiency will be 1 496 / 1 500 = about 99.5%.

With the electricity, the average efficiency of power delivery being in France of about 82%, we see the benefit obtained with the old locomotive!