Researchers Pull Ammonia From Thin Air, Potentially Delivering On-Site Fertilizer Production

Researchers from Stanford University and the King Fahd University of Petroleum and Minerals in Saudi Arabia have developed a device that can produce ammonia from fresh air air without the need for excessive power — with a view to allowing for the on-site production of agricultural fertilizer with a near-zero carbon footprint.

"An innovative method for on-site ammonia synthesis under ambient conditions has been developed using a catalyst mesh composed of magnetite (Fe₃O₄) and Nafion polymer," the researchers write in the abstract to their paper. "We pass air through the catalyst, which condenses microdroplets from atmospheric water vapor and uses nitrogen from the air, resulting in ammonia concentrations ranging from 25 to 120μM in one hour, depending on local relative humidity. Operated at room temperature and atmospheric pressure, this technique eliminates the need for additional electricity or radiation, thereby substantially reducing carbon dioxide emissions compared to the traditional Haber-Bosch process."

While the team's approach to turning water vapor and air into ammonia was first proven in the lab, the researchers have taken the work further and developed prototype devices that were field-tested in San Francisco's Bay area. In all cases, the devices successfully generated ammonia — a substance which is in high demand for agricultural fertilizer, with estimates suggesting that around a third of food production globally uses ammonia produced using the energy-intensive Haber-Bosch process and transported from factory to farm.

With the device the team has created, both the environmental impact of the Haber-Bosch process and the transportation of the resulting ammonia could be removed in favor of ammonia produced on-site using a fraction of the power. At least, if it scales. "The present system is truly primitive and needs improvement," the researchers admit. "In the field, we collected 20ml/hour and in the lab 500ml/hour. We believe that these amounts can be majorly increased with suitable engineering. A localized, sustainable green ammonia production approach, when developed, would reduce the reliance on large-scale industrial facilities and the associated transportation costs and emissions, contributing to a more sustainable agricultural ecosystem."

The team's work is available under open-access terms in the journal Science Advances; more information is available on IEEE Spectrum, which brought the project to our attention.