> Of course, during the oil age we've heavily used hydrocarbons to provide the
> energy part of the mix -- after all, it's a powerful and versatile fuel --
> but that's far from essential.
Not essential, but the concern about diminishing reserves of fossil fuels (or more to the point, the rate at which they can be drawn) is more about the cost of replacements in quantity than about whether there are replacements at all.
The link you provided goes on:
<http://www.garyjones.org/mt/archives/000303.html>
[....]
The problem [of the exhaustion of mined nitrates] became intense as the world girded for the war to end war. It is fitting that a Norwegian physicist Kristian Birkeland who was trying to develop a rail gun in order to attract funding for his research into electromagnetism accidentally discovered how to make nitrates with electricity when his experiment exploded due to a short circuit. He could smell nitrates in the smoky air and realized that he had just made fertilizer. He partnered with Sam Eyde, a civil engineer interested in hydroelectric power, to develop a fertilizer plant using the newly patented Birkeland-Eyde process for the production of Norgesalpeter - Norwegian Saltpeter, i.e. calcium nitrate. This made sense because there was no good way to use all that Norwegian electricity until power transmission from remote locations was developed some years later.
But the Germans had an even greater need for nitrates since they had strained relations with the world, and they also had an advanced chemistry industry. Haber and Bosch developed a cheaper method for nitrate production soon after and the Birkeland-Eyde process was made obsolete. Even Norsk Hydo, the company they founded, licensed the Haber-Bosch process and abandoned Birkeland-Eyde on the advice of Kristian Birkeland. Things got complicated for Norsk Hydo during the war since their customers included Germany and their owners included France, while Norway tried to remain neutral in the war.
[....]
Checking wikipedia on Haber-Bosch....
<http://en.wikipedia.org/wiki/Haber_Bosch_Process>
The Haber process now produces 100 million tons of nitrogen fertilizer per year, mostly in the form of anhydrous ammonia, ammonium nitrate, and urea. 3-5% of world natural gas production is consumed in the Haber process (~1-2% of the world's annual energy supply)[1][12][13][14]. That fertilizer is responsible for sustaining one-third of the Earth's population, as well as various deleterious environmental consequences.[4] Generation of hydrogen using electrolysis of water, using renewable energy, is not currently competitive cost-wise with hydrogen from fossil fuels, such as natural gas, and is responsible for only 4% of current hydrogen production.
[...]
So, yes, fertilizer can be made with electricity, and the original link mentions efforts to produce electricity renewably. But remember efforts like those in Iceland and northern Europe are striving to fulfill a slice of current electrical demand. The fact that electricity is now used for such a small fraction of nitrate production even though it's almost certainly cheaper (however you care to measure that) in industrial quantities than 100 years ago suggests that a shift to using renewable sources for nitrate production will make it dearer in the future.
Hence the peakista emphasis on *cheap* fossil fuels.
-- Andy