Ammonia is the most widely produced chemical, primarily used as a source for nitrogen fertilizer, and a major source of greenhouse gas emissions. Ammonia can be made without the usual fossil-fuel-powered chemical plants requiring high heat and pressure. The Earth itself is used as a geochemical reactor, producing ammonia underground. The processes use Earth’s naturally occurring heat and pressure (no charge, no emissions), and the reactivity of minerals present in the ground. Water is injected underground (into an area of iron-rich subsurface rock) carrying with it a source of nitrogen and particles of a metal catalyst, allowing it to react with the iron to generate clean hydrogen, which in turn reacts with the nitrogen to make ammonia. A second well pumps that ammonia to the surface.
news.mit.edu/2025/clean-ammonia-mit-engineers-propose-going-underground-0121