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Earth’s Natural Forces Could Transform Fertilizer Production — Underground

MIT researchers tap into underground heat and pressure to create ammonia without energy-intensive factories

A chance discovery in West Africa decades ago has led scientists to a potentially game-changing method for producing fertilizer that could slash the chemical industry’s carbon footprint. By harnessing Earth’s natural heat and pressure instead of energy-hungry factories, researchers have successfully generated ammonia using just rocks and water – without any additional energy input or carbon emissions.

The development, reported in Joule on January 21, 2025, traces its origins to an unusual find in 1980s Mali, where locals discovered a well mysteriously streaming with hydrogen gas. Scientists later determined this was caused by a natural chemical reaction occurring between water and rocks beneath the Earth’s surface.

“It was an ‘aha’ moment,” says Iwnetim Abate of the Massachusetts Institute of Technology (MIT), the study’s senior author. “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.”

The timing couldn’t be more critical. Current industrial ammonia production, vital for both fertilizers and potential future clean fuels, consumes approximately 2% of global energy. For every ton of ammonia produced, the process releases about 2.4 tons of CO2, making it the chemical industry’s largest carbon dioxide emitter.

To test their “Earth factory” concept, the research team created a system mimicking underground conditions. They exposed iron-rich minerals to nitrogen-containing water, triggering a reaction that produced what they call “geological ammonia.” The process worked even at room temperature, though efficiency improved significantly at higher temperatures.

When using olivine, a naturally occurring iron-rich rock, and adding a copper catalyst at 300°C (572°F), the team produced approximately 1.8 kilograms of ammonia per ton of rock within 21 hours.

“These rocks are all over the world, so the method could be adapted very widely across the globe,” Abate notes. However, he acknowledges the challenges ahead: “There’s a whole other level of complexity that we’ll need to work through.”

The economic prospects look promising. Producing ammonia through this geological method costs about $0.55 per kilogram, comparable to conventional production costs of $0.40–$0.80. Through his company Addis Energy, Abate aims to scale up the process with pilot testing planned for 2026.

The research also opens unexpected possibilities for addressing water pollution. “Nitrogen sources are considered as pollution in wastewater, and removing them costs money and energy,” explains Yifan Gao, the study’s first author. “But we may be able use the wastewater to produce ammonia. It’s a win-win strategy.” This integration could add $3.82 in profit per kilogram of ammonia produced.

Beyond its practical applications, the discovery provides intriguing insights into Earth’s chemistry. As MIT’s Ju Li points out, “Ammonia is pretty important for life.” Before this finding, lightning strikes were thought to be the only natural process besides microbes capable of producing ammonia on Earth. “That’s why the geological production of ammonia is quite interesting when you think about where life came from.”

The road to implementation involves significant engineering challenges, including drilling into iron-rich rock formations, managing water injection systems, and understanding how rocks interact with gases and liquids under varying conditions. But if successful, this approach could provide a sustainable solution for one of the chemical industry’s most energy-intensive processes.


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