There’s not much you can make with three ingredients.
The possibilities are even fewer when two of those ingredients are water and air.
But for researchers from The Grainger College of Engineering at the University of Illinois Urbana-Champaign, a recipe of air, water and electricity yields something valuable: ammonia, an essential precursor for nitrogen fertilizer. The need for natural, sustainable fertilizers is growing rapidly as crop producers prepare to feed a global population expected to reach 10 billion by 2060.
Conventional nitrogen fertilizer production—also known as nitrogen fixation—typically relies on the Haber-Bosch process, which uses atmospheric nitrogen and hydrogen from methane as feedstocks. These gases are processed at high temperature and high pressure to produce ammonia gas. Although Haber-Bosch is highly efficient, it is also complex and only economical at very large scales: there are only about 500 Haber-Bosch plants worldwide, and one-third are in China. The centralized and privately-owned nature of these plants makes them difficult for smaller countries to access, and their reliance on methane produces a high volume of carbon emissions.
Researchers from The University of Illinois sought to develop an alternative process for nitrogen fixation that was cheaper, more accessible and not reliant on hydrogen, with the ultimate goal of turning air, water and electricity into food—using as few resources as possible. Led by Mohan Sankaran, professor of nuclear, plasma and radiological engineering, the group was funded by the Defense Advanced Research Projects Agency (DARPA) on the Cornucopia program to develop a compact, modular reactor that generates ammonia with nitrogen and water instead of hydrogen. Using an electrochemical approach, their device operates with just four steps: pouring water into a cell, connecting an air supply, adding a source of electricity and pressing a button. With collaboration from postdoctoral researcher Mohammad Ali Eslamisaray, what started in 2022 as a single plasma electrode has now been scaled up to a system of hundreds of electrodes working in parallel to make kilograms of nitrogen product per day—on a reactor small enough to fit on a dining room table.
“The DARPA project required us to scale up while keeping the reactor as small, light and low power as possible,” Sankaran said. “They wanted it to fit on a mobile unit so it could be used in remote locations. It was an aggressive challenge, but it pushed us to design creatively.”
The group’s patent-pending research illustrates how plasma-based methods can be used to efficiently produce tunable nitrogen products, from nitrate to ammonia, through precise control of process conditions. This method served as the foundation for their pilot reactor, which they hope to commercialize. The Illinois Grainger engineers’ device is smaller, more adaptable and less dependent on external inputs than current processing techniques and can be powered by wind, solar or electrical infrastructure.
“We see this as an agile system that can change depending on the needs of individual farms,” Sankaran said. “We’re trying to be flexible depending on downstream need.”
Now that the current reactor has completed its pilot phase, Sankaran and Eslamisaray are focused on their next task: building the product’s final version and raising funds to expand its reach—both in industry and globally.
“We’ve seen a lot of unpredictability in the fertilizer market in recent years,” Eslamisaray said. “Producing fertilizer locally gives farmers more stability and peace of mind knowing they’ll have access when they need it. Decentralized systems are going to become an increasingly competitive alternative to conventional fertilizer production in the coming years.”
Sankaran is confident the Illinois Grainger engineers’ reactor can have a measurable impact on global sustainability efforts thanks to its minimal resource requirements.
“There are places in the world that don’t have access to fertilizer,” Sankaran said. “My research experience has allowed me to use things I’m passionate about to solve a world problem.”
Illinois Grainger Engineering Affiliations
Mohan Sankaran is an Illinois Grainger Engineering professor in the Department of Nuclear, Plasma and Radiological Engineering. He is affiliated with the Materials Research Laboratory. Sankaran holds the Donald Biggar Willett Professor appointment.
Distribution Statement "A" (Approved for Public Release, Distribution Unlimited).