"There's plenty of lower grade sources available." Energy intensity always goes up with lower grade sources. Its not just raw "jackhammer power" or whatever t

"There's plenty of lower grade sources available." Energy intensity always goes up with lower grade sources. Its not just raw "jackhammer power" or whatever the material is pumped or drilled out with, but all the related costs of transport and especially labor. For example if you need to pay your employees enough to survive during an era of $400/barrel oil, then that resource may simply be un extractable. Too many economic projections are based on absolutely everything staying the way it is other than... (insert commodity) increasing price to 5 times current price. Well good luck not affecting everything else including especially process input materials. That ties in with the level of socioeconomic stability a resource needs. Perhaps that exotic shale refinery is theoretically economically exploitable at a mere $250/barrel oil, but there's a slight problem in that the society/culture/economy needs to be stable enough to build it and it won't be stable enough at $250, perhaps it needs to average well under $100/barrel to create the infrastructure and trained skilled workers required to build and operate the facility... So if the price is low enough for society to be stable enough to build and operate the plant, it won't work economically, and if the price is high enough to build and operate the plant financially, society and the greater economy will be in complete ruins so it can't be built or operated. In your example the only way to afford refining phosphate out of raw seawater or whatever would involve raising the price until everyone is dead of starvation, at which point there's little purpose in a perfectly operating plant other than as some sort of interstellar robotic art exhibit, or more realistically its hard to build a plant when a famine inspired nuclear war is happening overhead at the same time and the place you needed to order drill bits from on the other side of the planet just got nuked. This is aside from the aesthetic issues. So if there were 95% unemployment, then we'd have enough starving workers to, I donno, create a "chunnel" all the way under/across the atlantic ocean or something. With the obvious disadvantage that no matter how cool that mega project would be in theory all by itself, it requires 95% unemployement, of course, which isn't all that appealing when considered in toto. So the aesthetic issue is you might have to strip mine a national park or two when obtaining that low grade ore, perhaps. (Edited to add: And this is what collapse actually looks like. Real collapse, not hollywood.)