Ammonia, the most produced chemical globally, is essential for nitrogen fertilizer, but its traditional manufacturing methods significantly contribute to greenhouse gas emissions, making it a primary source of emissions within the chemical industry. Researchers at MIT have unveiled a groundbreaking method that could revolutionize ammonia production by harnessing the Earth’s natural processes.
Instead of relying on fossil fuel-powered plants that operate under extreme heat and pressure, this innovative approach uses geological formations as natural reactors to produce ammonia underground. By leveraging the Earth’s inherent heat and pressure, alongside the natural reactivity of existing minerals, the researchers aim to create a more sustainable process.
Here’s how it works: The team injects water deep underground into iron-rich rock formations. This water carries nitrogen and metal catalyst particles that react with iron to generate clean hydrogen. This hydrogen then combines with nitrogen to form ammonia, which is subsequently pumped back to the surface using a second well.
This promising process, detailed in an article published in the journal Joule, represents an innovative step forward in sustainable chemical production. Co-authors of the study include MIT materials science and engineering professors Iwnetim Abate and Ju Li, alongside graduate student Yifan Gao and several other MIT researchers.
Yifan Gao expressed his enthusiasm, recalling, “When I first produced ammonia from rock in the lab, I was so excited. This method is a completely new approach to ammonia synthesis.”
Traditionally, ammonia is produced using the Haber-Bosch process, a method developed in the early 20th century that replaced diminishing natural nitrogen sources like bat guano. However, this process demands significant energy, requiring temperatures around 400 degrees Celsius and pressures of about 200 atmospheres, making it inefficient in regions lacking such facilities, like sub-Saharan Africa and parts of Southeast Asia, stunting agricultural potential.
While the Haber-Bosch process is undoubtedly effective—contributing to the food supply of approximately 2 billion people—the environmental and energy costs necessitate the exploration of alternative methods. Estimates indicate that 20% of greenhouse gas emissions from ammonia plants result from fuel combustion for heat, while hydrogen production leads to an additional 80% of these emissions. Traditionally, hydrogen required for ammonia production is derived from methane gas, which generates carbon dioxide as a byproduct.
Although alternative methods for producing low- or zero-emission hydrogen exist—such as electrolysis driven by solar or wind energy—these can be prohibitively expensive. This realization drove Abate’s team to investigate geological hydrogen production, a potentially abundant resource found in regions where chemical reactions between water and iron-rich rocks generate hydrogen naturally.
Abate noted, “We can use the Earth as a factory to produce clean flows of hydrogen.” He envisioned linking underground hydrogen production with the Haber-Bosch process, thereby addressing the challenge of hydrogen capture and storage. The design cleverly allows for ammonia, a more manageable substance than hydrogen, to be the only material extracted from these underground reactions.
By also including a nitrogen source in the injected water, the team can facilitate efficient bonding between hydrogen and nitrogen in the subterranean environment, which naturally provides the necessary temperature and pressure for ammonia production. “We call this geological ammonia,” Abate explains, highlighting the ingenuity of utilizing the subterranean landscape for chemical synthesis.
Transporting ammonia is cheaper and less complicated than hydrogen, with existing infrastructure already supporting an extensive network of ammonia pipelines across the U.S. This makes ammonia not only a sustainable alternative but also a commercially viable one, as its production is expected to triple by 2050 for various applications, including fertilizers and as an alternative fuel source.
One innovative facet of the geological ammonia process is the potential to use untreated wastewater as a water source rich in nitrogen, addressing waste treatment challenges while simultaneously creating valuable products. Gao highlighted the absence of direct carbon emissions in this approach, indicating that it could potentially reduce global CO2 emissions by 1%.
Throughout their research, the MIT team overcame numerous challenges, refining their process through extensive testing of catalysts and conditions. The initial experiments were funded through MIT’s Climate Grand Challenges program, with additional support from the National Science Foundation.
Professor Yet-Ming Chiang remarked on the novelty of this approach, noting that it represents a shift in how we might view the Earth—not just as a source of materials, but as a vital component in chemical production. The reactions occur rapidly, answering the critical question of whether geological timescales limit such processes.
Professor Elsa Olivetti underlined the significance of this research for large-scale sustainable development. She emphasized how the innovative thinking behind the project helps MIT contribute to meaningful climate solutions. “This creative thinking is invaluable,” she stated.
While this foundational work was conducted in the lab, the next step involves validating the process in a real underground environment, anticipated within the next one to two years. Abate expressed optimism about the potential applications of this method for other chemical production processes in the future.
The team is currently pursuing patent protection for their work and aims to scale their findings for commercial use. Looking ahead, Gao noted, “Our primary focus will be on optimizing the conditions and scaling up tests to enable practical applications for geological ammonia soon.”
The MIT research team also included Ming Lei, Bachu Sravan Kumar, Hugh Smith, Seok Hee Han, and Lokesh Sangabattula. The project exemplifies an exciting step forward in sustainable chemical production, paving the way for innovative solutions to some of today’s pressing environmental challenges.
Photo credit & article inspired by: Massachusetts Institute of Technology
