The search for a new ammonia-synthesis method has now driven research and development work underground, literally. Addis Energy (Somerville, Mass.; www.addisenergy.com) is launching a subsurface synthesis technology that takes advantage of geologic chemistry to produce ammonia. “Addis Energy’s process uses iron-rich rocks in the earth’s subsurface as a reactive medium. Water, a nitrogen source and a catalyst are injected into these formations, where ferrous iron is oxidized. In this reaction, iron binds with oxygen from water molecules, liberating hydrogen atoms. These hydrogen atoms then react directly with nitrogen in an aqueous-phase reaction to form ammonia,” explains Addis Energy co-founder and chief executive officer Michael Alexander.
Unlike traditional ammonia synthesis via the Haber-Bosch process, no molecular hydrogen is formed as a reaction intermediate. Instead, says Alexander, “hydrogen is generated in situ from water and immediately incorporated into ammonia underground, using naturally available subsurface heat and pressure.”
While much effort across the industry has gone into simulating geologic hydrogen production, Addis Energy is the first company to investigate the conversion of geologic hydrogen to ammonia in situ by adding a nitrogen source. Building upon intellectual property developed at Massachusetts Institute of Technology (MIT; www.mit.edu), Alexander points to work published in 2025 by Addis Energy co-founder and chief science officer Iwnetim Abate in the journal Joule identifying copper and nickel cations as “catalysts of interest to accelerate the oxidation of ferrous iron and facilitate hydrogen liberation from water, enabling the subsequent reaction with nitrogen to form ammonia.”
Once ammonia is formed, unreacted water is recirculated and reinjected into the subsurface. A key to the technology’s industrial feasibility is its reliance on established “off-the-shelf” equipment and processing methods that are already widely used in oil-and-gas and geothermal processes. So far, the technology has been demonstrated at laboratory and benchtop scales under simulated subsurface conditions. “Experiments are conducted at elevated temperatures and pressures representative of subsurface environments, including core flood systems that pump fluids through unaltered rock samples to replicate temperature, pressure and flow conditions. These experiments have shown the potential for cost-advantaged ammonia production relative to Haber–Bosch,” notes Alexander. Following a round of seed funding in December 2025, next on the horizon for Addis Energy will be to scale up to larger reactors and finalize geological screening and permitting for a first pilot site.