Much of what you've written is simply false, much the rest hopelessly naive. Really, if you're interested in an intelligent discussion, educate yourself.

1. If you're referring to Smil, you're simply incorrect. As for pseudonymously publised works, there's a long tradition of that, as well as of anonymous publishing.

https://en.m.wikipedia.org/wiki/Vaclav_Smil

https://en.m.wikipedia.org/wiki/List_of_works_published_unde...

https://en.m.wikipedia.org/wiki/List_of_anonymously_publishe...

1. On food production: the natural rate of agriculture peaked arguably in the 19th or early 20th century. Again, what's boosted food output has largely been a transfer of plant-derived photosynthetic energy from other purposes (disease resistance, physical structure), to producing more actual foodstuffs: grain, germ, and starch. Most especially in the case of the major staple crops: wheat, maize, rice, and potatoes. Avialable arable land, topsoil, suitable climatic regions, freshwater, and fertilisers are all limiting factors. On which you might also care to refer to Leibig's Law of the Minimum. As to the topic of my coment, virtually all manufacturing, transport, and processign activities require one or more of coal, oil, or gas. Absent these, no steel, little aluminium (hydroelectric can substitute), cement, and many other materials, again, Smil addresses this in depth), no overland trucks, far more difficult overland rail, ocean cargo is restricted to sail or sail-power hybrids, and no air travel.

2. Demographic plots of population say otherwise.

3. The point isn't that nitrogen is an energy source, but that it's a fundamentally required and limiting nutrient, and that breaking those chemical bonds are precisely what requires so much energy. The initial question asked was "what changed", and that's what I've answered. Malthus didn't forsee either the chemical energy bounty of fossil fuels, or the possible addition of artificial fertilisers. Haber-Bosch reflects the combination of these factors. You'd have to both continue the 2nd, and substitute for the 1st factor.

4. Cost of mineral extraction rises precisely as a reciprocal of their concentration. Concentrations of mined ores has fallen tremendously. The problem with the "more energy makes recycling possible" argument is that many or most of those energy systems are themselves dependent on scarce mineral resources for their production, transformation to useful forms, and especially, storage.

As ecologists note (Howard Odum at depth), humans, and life generally, exploit entropic gradients. These include not only energy gradients as in fossil fuels, but gradients of ore concentrations and even natural systems producing useful exploitable circumstances.

5. You're arguing a point I didn't make. It's not that fertilisers are made from fossil fuels (though in fact many are). It's that even those fertilisers which aren't critically limited by dependency of fossil-fuel based synthesis are themselves in crucially short supplies. Most notably phosphorus, though on a longer scale, even reasonably abundant potash becomes constrained (1-5 centuries).

Again: life exploits entropic gradients. Humans have overcome contraints of previous gradients (a near 100% renewables regime, based on agriculture, small wind and water kinetic inputs, and small-scale extractive mining), by bootstrapping a vast enterprise of energy and minerals extraction. It's produced a one-time boon for the species.

Even highly abundant mineral resources such as iron and oxygen are available to us through previous biological activity on the planet. Look up "banded iron formations" and "the great oxygenation event" for background. Humans have plowed through a billion years of iron accumulation in a couple of centuries. While not fully exhausted, future generations will have massively less rich ores to mine. If they're starting from a technological deficit on top of that, the process of re-bootstrapping civilisation will likely prove challenging.

Technologies can both lead to newly avialable gradients such as coal, oil, and gas, which were less attractive earlier in that they weren't universally distributed -- easier to walk into the local woods to extract fuel than haul coal thousands, or even tens, of miles. An entire infrastructure of railways, paved highways, pipelines, shipping systems, and high-pressure or low-temperature containment were required to make these fuels vialble, a process which took much of a century to fully develop.

Renewables are the energy of the future, of that I've no doubt. The question is the scale and technological scope of their utilisation. Nuclear power is the curveball, though conventional once-through uranium and plutonium designs are sufficient only for about 7-8 more decades at present levels of use. Increase the provision of electricity from them and that falls to about 6 years. Seawater extraction of uranium at 2ppm is unproven and would require vast marine structures (the marine environment is a bitch to engineer for). Breeder systems offer a longer horizon, but with massive systemic risks.

Neither, of themselves, address liquid fuels, coking fuel (14% of coal consumption), or other affordances of hydrocarbons, though there are some possible options (Fischer-Tropsch fuel synthesis, possibly recapturing carbon from seawater among the more interesting possibilities). Even these would raise the energy cost of liquid hydrocarbons by a factor of about 80.