[astrodust]

Every single thing you're describing here is catastrophic and world-ending.

The world without oil looks like North Korea. The world with oil looks like South Korea.

Without fertilizer there will be mass starvation, this is absolutely assured. It doesn't matter about production or transport. There won't be any food in the first place.

[dozzie]

> Every single thing you're describing here is catastrophic and world-ending.

I fail to see how replacing a Diesel engine that burns diesel oil inside its cylinders with a Stirling engine that burns dried guano in an external combustion chamber is world-ending.

Not to mention that old style diesel engines usually can run on cooking oil(!) or ethanol(!), so the migration to alternative propulsion wouldn't need to be that immediate. Transportation of goods critical to survival (e.g. food) could still be secured.

And we aren't discussing the world where fertilizers disappeared. We were talking about the world without gasoline.

[VLM]

Far upstream the refinery machine you're looking for is a hydrocracker and wikipedia link

https://en.wikipedia.org/wiki/Cracking_(chemistry)

Cracking is not a net energy gain... However, if you're refining more asphalt than you know what to do with and have a shortage of shorter chain hydrocarbons, you can at considerable cost (economically and energeticaly) crack them and turn a useless pile of asphalt into burnable gasoline.

Coal to gas is convoluted. Coal to methanol somewhat more reasonable. Methanol being quite toxic is no laughing matter but then again benzene and mystery meat in gasoline is no laughing matter, probably "methanol causes blindness" would be all over the clickbait but it wouldn't be much larger of a problem than cancer from gasoline at a societal level.

All you need to end the world is about three days without food deliveries. That's about a factor of a hundred faster than the NIMBY permitting problems preventing installing steam engine rail between food warehouses and retail stores or whatever.

Fertilizer IS natgas. There's no such thing as a natgas or oil well, there's just wells with different ratios of natgas to oil, ranging from admittedly near 99% of one or the other to darn near 50:50 (by mass or volume). Its really quite problematic and dangerous. Yes the average chain length of crude oil is a nice stable diesel fuel but the std deviation is quite high leading to amazing explosions and fires due to 1% by mass being butane bubbling out catching fire then setting the rest of the plant on fire. Crude oil really is annoying and if it weren't so energetically valuable I donno if we'd use it as a feedstock for everything else, just TDP natural oils or something. Not to mention crude oil is full of "stuff" vanadium and sulfur and whatnot.

The wikipedia you want is

https://en.wikipedia.org/wiki/Haber_process

Basically you mix steam and natgas to get hydrogen, then you mix hydrogen with atmospheric nitrogen (under immense pressure and high temp) to make ammonia, quite an important nitrogen fertilizer directly, but also indirectly via acid plants and much hand waving the other fertilizers kinda sorta depend on ammonia and there's no other industrially viable nitrogen source.

For fun if you really want to trigger "hydrogen economy" enthusiasts you can point out ammonia is a better hydrogen storage technology than any other tech we have and its still ridiculously impractical.