Similarly, in the real world, the entire energy sector itself is now strongly interacting with other scarce resources such as phosphate, water or farmland to create profoundly dangerous negative synergies.

Exactly right. The uphill side of the oil age was driven by the same but positive synergies! I would love to see some young (or at least energetic) mind trace out the upside synergies in detail, not as an abstract academic exercise, but in order to give us a better insight into the "negative synergies" that are operating now. How closely does the unwinding mirror the winding? Far beyond just interesting.

I don't think they invert like your saying. Here is why. To use Old Testament slang :)

Oil production beget NPK beget demand for Phosphorous
Low oil production beget corn ethanol beget NPK beget demand for Phosphrous.
Heavy Sour crude beget demand for NG for coking beget no NG for NPK and distilling beget expensive corn ethanol

The problem is demand created by more oil actually increases and oil suppy decreases it does not decrease so the less oil we have the more demand we have for all the other critical commodities with the center being NPK and NG.

Oh crap :)

But this is why I've said we won't go down because of oil depletion partial substition of biofuels increased EROI etc are going to result in us running out of cheap NPK or NG before we run out of oil.

Once cheap NG and NPK fertilizer are gone the party is over. And I bet the price increases in these once they become critical will blow your mind.

We can substitute for oil esp in transportation we may not "like" changing our lifestyle but we cannot easily substitute for NG and NPK.