I believe it would be possible to convert existing diesel-electric locomotives to burn natural gas. I know that when I was studying mechanical engineering in the 1950s, “dual-fuel” engines in sizes comparable to current locomotive power were used in domestic electric power generation. These were basically similar to diesel, obtaining 95% of their power from natural gas, with fuel ignition provided by a small charge of diesel fuel injected into the cylinder at the start of the power stroke. The LNG, carried in the “fuel tender”, could be vaporized by waste heat from the engine exhaust. This would greatly reduce the cost of new power by saving the existing locomotive engines with fairly simple modifications.
Yes it is.