Researchers build green fertilizer system to reuse wastes, cut emissions

Researchers from the U.S. Midwest want to remove some greenhouse gas emissions from fertilizer.

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Research teams from Iowa State University and Wichita State University in Kansas are developing a system that captures waste nitrogen and carbon dioxide to produce a green fertilizer that reduces emissions of nitrous oxide, a greenhouse gas more potent than carbon dioxide.

The system’s big goal, according to a summary, “is to promote N₂O and CO₂ relieved nitrogen fertilizers with economic resilience and environmental consciousness as an innovative way to mitigate the challenges posed upon climate change-threatened Midwest farming and ranching communities.”

Wenzhen Li, a professor of chemical and biological engineering and the Herbert L. Stiles Faculty Fellow, will lead Iowa State’s work on the project. Other team members include researchers from soil science, electrical and computer engineering and agriculture departments.

The team’s tasks will include designing materials, processes and reactors for the electrochemical capture and conversion of waste nitrogen and carbon dioxide for a fertilizer known as green urea, modeling the nitrogen cycle in crops, developing and testing nitrogen sensors for crops and educating farmers and ranchers about the new fertilizer.

The researchers also want to boost the project’s sustainability by using wind and solar energy to power the electrochemical synthesis of the green fertilizer.

“We want to take advantage of abundant renewable energy that Iowa and Kansas currently generate and use,” Li said.

Shuang Gu, an associate professor of mechanical engineering at Wichita State, will lead the project in Kansas. He’ll work with team members from biological sciences, engineering and public affairs.

The Kansas team’s tasks will include capturing and concentrating nitrate, separating urea, studying soil microbial communities, conducting life-cycle assessments of green fertilizers and determining societal impacts of green fertilizers.

The Iowa State and Wichita State researchers have worked together on other projects, so it made sense to pursue a new collaboration.

“There is a seamless synergy between ISU in Iowa and WSU in Kansas in terms of shared common problems, united interest in Midwest farming and ranching, and complementing research expertise and education strength,” Gu said.

Li said the project will also create a system of technologies and understandings that could cut nitrous oxide emissions from fertilizer.

The researchers will figure out how to capture waste nitrogen and carbon dioxide from agricultural runoff. They’ll also develop technology to synthesize green urea from the collected nitrogen and carbon dioxide.

They will also do life cycle and economic analyses of using green fertilizer, develop advanced sensors for in-field measurement of nitrogen use by plants, study plant metabolism of nitrous oxide, look at the impacts of policy changes and work to encourage the use of green fertilizers.

“Living in the Midwest, the heart of agriculture, we felt obliged to do something to alleviate this national problem of greenhouse gas, nitrous oxide emission,” wrote Gu and Li.

“The nitrous oxide-relieved nitrogen fertilizer could strengthen the long-term thriving and prosperity of Midwest agriculture, while mitigating climate-change issues.”