I wrote recently about two pathways for ammonia production technology development: improvements on Haber-Bosch, or electrochemical synthesis.
Last week, I covered some of these Haber-Bosch improvements; next week, I'll write about electrochemical processes. This week, I want to write about some innovations that don't fit this two-way categorization: they don't use electrochemistry and they don't build upon the Haber-Bosch process, and that might be the only thing that links them.