Scientists from the Massachusetts Institute of Technology (MIT) have discovered a way to produce ammonia—a key ingredient in fertilizers—by harnessing the Earth’s own heat and chemical reactions.
The achievement could potentially revolutionize one of the world’s most energy-intensive industries, thanks to a novel process detailed in a new study published January 21 in Joule. The findings could also offer a sustainable alternative to current ammonia production methods that are major contributors to global carbon emissions.
Instead of using high-energy, high-pressure reactors, MIT found that ammonia can be created deep underground by mixing nitrogen-rich water with iron-rich rocks—without requiring any external energy input or producing carbon dioxide (CO₂).
“It was an ‘aha’ moment,” senior author Iwnetim Abate of MIT said in a recent statement. “We may be able to use Earth as a factory, harnessing its heat and pressure to produce valuable chemicals like ammonia in a cleaner manner.”
A Natural Factory Beneath Our Feet
The idea behind this innovation dates back to a surprising geological discovery in Mali, West Africa, in the 1980s. The well was originally found when a townsman lit a cigarette near the well only to find it leaking pure hydrogen gas. Experts later traced this to a natural reaction between water and rock deep below the Earth’s surface.
Ammonia is essential for producing fertilizers that support global food production, and it is also being explored as a potential clean fuel. However, conventional ammonia production is extremely energy-intensive, consuming around 2% of the world’s total energy supply and emitting over 2.4 tons of CO₂ for every ton of ammonia produced. This makes it the chemical industry’s largest single source of carbon emissions.
A More Sustainable Way to Make Ammonia
To test their “Earth factory” concept, the MIT team built a laboratory system that mimics natural underground conditions. They exposed synthetic iron-rich minerals to nitrogen-infused water, triggering a reaction that produced ammonia. Remarkably, this process worked without any external energy input and emitted no CO₂.
The team then replaced their synthetic mineral with olivine, a naturally occurring iron-rich rock, to simulate real-world conditions. Adding a copper catalyst and heating the system to 300°C (572°F) significantly boosted ammonia production. Within 21 hours, they generated about 1.8 kg (4 lb) of ammonia per ton of rock, proving that the method is feasible and scalable.
“These rocks are all over the world, so the method could be adapted very widely across the globe,” Abate stated in the press release. However, he acknowledged that practical implementation will be challenging, requiring deep drilling into iron-rich rock formations and managing complex underground reactions.
A Cost-Effective and Environmentally Friendly Alternative
Despite the technical challenges, this method’s economic potential is promising. Producing ammonia through this geological process costs about $0.55 per kilogram, comparable to traditional methods‘ $0.40–$0.80 per kilogram range.
Additionally, the researchers see an opportunity to integrate this process with wastewater treatment.
“Nitrogen sources are considered pollution in wastewater, and removing them costs money and energy,” Yifan Gao, the study’s first author added in a recent statement. “But we may be able to use the wastewater to produce ammonia. It’s a win-win strategy.”
The researchers suggest in their paper that this approach could even generate an extra profit of $3.82 per kilogram of ammonia.
A Step Toward Greener Chemistry
Beyond its economic benefits, this method provides insights into natural chemical processes that could have contributed to the origins of life.
“Ammonia is pretty important for life,” MIT researcher Ju Li, a senior author of the study noted in a recent press release. “Apart from microbes, the only other natural way to produce ammonia on Earth is through lightning striking nitrogen gas. That’s why the geological production of ammonia is quite interesting when you think about where life came from.”
The researchers are now working on scaling up the process, with plans for a pilot test by 2026 through Addis Energy, a company co-founded by Abate. If successful, this approach could help make ammonia production more sustainable while reducing the environmental impact of agriculture and industry.
Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on BlueSky or contact her via email at kenna@thedebrief.org