[Olog-hai]

This is going to be a real debacle. There’s a larg enough gulf between the BTUs of diesel fuel and the BTUs of natural gas to make a significant dent in engine efficiency. With diesel, locomotives approach (and sometimes exceed) 40 percent heat efficiency; that’ll be cut a great deal (perhaps as much as half) with a switch to natural gas. Those big prime movers will now need spark plugs, too, making yet another dent in heat efficiency (more parts, more thermodynamic breakdown). Gensets have way more moving parts than the larger diesels, too (imagine doubling the number of cylinders, and then doubling the maximum revolutions per minute that the engine operates at).

[muffaletaman]

Hmm...

According to the WSJ article, the same number of BTUs from diesel cost about $4 now versus about 50 cents from natural gas at current industrial prices.

Even with locomotive conversion and natural gas liquifaction costs, looks like there could be plenty of margin for this to work.

After all, if NG is so much cheaper than coal for power plants (plus lower CO2 emissions), then it should be somewhere between “possible” to “very likely” that it will work for the big prime movers in locomotives.

It is definitely worth testing.

[Wonder Warthog]

"There’s a larg enough gulf between the BTUs of diesel fuel and the BTUs of natural gas to make a significant dent in engine efficiency. With diesel, locomotives approach (and sometimes exceed) 40 percent heat efficiency; that’ll be cut a great deal (perhaps as much as half) with a switch to natural gas. Those big prime movers will now need spark plugs, too, making yet another dent in heat efficiency (more parts, more thermodynamic breakdown)."

Not necessarily. There is a dual-injection cycle in which both natgas and a SMALL amount of diesel are injected simultaneously. The diesel serves as the ignition source when compressed, igniting the natgas (thus no spark plugs), and the total efficiency is supposedly HIGHER than diesel alone.