MIT’s Method Produces Ammonia Underground with Zero Energy

Ammonia holds great promise as a future fuel source, but current production methods make it a major contributor to environmental pollution. Researchers at MIT have now developed a groundbreaking technique that uses Earth’s natural heat and minerals to produce ammonia in a cleaner, more sustainable way.

Currently, ammonia ranks as the second-most produced chemical globally, with about 80% of it used in agricultural fertilizers. However, traditional ammonia production consumes roughly 2% of the world’s fossil fuel energy and accounts for approximately 1% of global manmade greenhouse gas emissions. To put this into perspective, each ton of ammonia produced emits about 2.4 tons of carbon dioxide (CO2).

Despite these environmental challenges, ammonia—a compound of nitrogen and hydrogen—has significant potential in the energy sector. It can store over 20 times the energy by weight compared to lithium-ion batteries and can burn cleanly when managed properly. Developing greener methods to produce ammonia could significantly contribute to reducing carbon emissions while meeting energy demands.

Advancements in Green Ammonia Production

Progress in sustainable ammonia production has been accelerating. In 2022, three Danish energy companies launched the world’s first green ammonia plant, capable of producing 5,000 tons annually using only solar and wind energy. By 2026, Norway plans to introduce the first ammonia-powered container ship. Other innovations, such as zero-emission ammonia-electric semis and ammonia-powered tractors, further highlight the compound’s green potential.

Building on this momentum, MIT researchers have now introduced a method to produce ammonia without external energy inputs or CO2 emissions, opening new possibilities for sustainable production.

Inspiration from Nature

The idea for the method came from a hydrogen-rich well in Mali, West Africa. Discovered in the 1980s, the well contained streams of hydrogen gas, later found to result from chemical reactions deep within the Earth’s crust between rocks and water.

It was a eureka moment, said Iwnetim Abate, the study’s senior author. We realized that the Earth itself could act as a factory, using its natural heat and pressure to produce valuable chemicals like ammonia in a cleaner way.

To test the concept, Abate’s team designed a model system that injected nitrogen-enriched water into synthetic iron-rich minerals, replicating conditions found beneath the Earth’s surface. This process successfully produced ammonia without releasing CO2 or requiring external energy.

When the researchers replaced the synthetic iron with olivine, a naturally occurring iron-rich mineral, they added a copper catalyst and increased the temperature to 300°C (572°F), simulating conditions miles underground. The nitrogen in the water reacted with the iron, generating hydrogen, which then combined with nitrogen to produce ammonia. This process yielded approximately 1.8 kg (4 lbs) of ammonia per ton of olivine.

These minerals are abundant worldwide, making this method adaptable on a global scale,Abate explained. However, he acknowledged that significant challenges remain, particularly in drilling deep into the Earth and managing the interactions between injected fluids, produced gases, and the surrounding bedrock.

Future Prospects for Green Ammonia

Despite these complexities, Abate is optimistic about the technology’s potential. His team hopes to test the system in real-world conditions within the next year or two and believes it could even utilize nitrogen from wastewater as an input.

This is a major breakthrough for sustainable development, said Geoffrey Ellis, a geologist with the U.S. Geological Survey who was not involved in the study. Although further work is needed to validate the method at pilot and commercial scales, this concept is transformative. Engineering a system that optimizes the natural process of nitrate reduction by iron is an ingenious approach likely to inspire further innovations.

The research team has filed a patent for their technique, marking a significant step toward scaling this innovative method and advancing green ammonia production.

Read the original article on: New Atlas

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