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By Rachel Hergett, MSU News Service

BOZEMAN — Well-known sources like sunlight, moving water and wind generate sustainable energy which can be stored for later use. But what if we could turn the air around us into usable fuel when the wind isn’t blowing?

Montana State University researcher Michael Mock envisions a future in which homes have solar panels on the roof and a machine in the basement that collects nitrogen from the air and converts it into ammonia. The compound effectively stores energy within its nitrogen-hydrogen bonds, Mock said, unlike many other sustainable energy sources which store electricity in batteries.

“You can store much more energy in a chemical bond,” said Mock, an assistant professor in the Department of Chemistry and Biochemistry in the College of Letters and Science at MSU who studies the mechanics of this process.

In this nitrogen-based energy cycle, ammonia can either act as a cache of hydrogen or power specialized fuel cells. While it is now mostly used in agricultural and chemical applications, ammonia has a 100-year history of use as a fuel, including powering Belgian military buses in World War II when other energy sources were in short supply. Much like propane, which is a petroleum byproduct, ammonia can be compressed into a liquid for storage and then converted to other forms of energy.

“The technology is not new,” Mock said. “The biggest problem is that it’s very energy intensive to convert nitrogen into ammonia.”

Nitrogen in the air is a diatomic element, meaning there are two atoms in a nitrogen molecule. That molecule must first be split to free the single atoms of nitrogen needed to bond with three hydrogen atoms and create ammonia.

“It’s probably one of the most challenging chemical transformations known,” said Mock, who has been at MSU since August 2018 after a decade studying similar processes at the Pacific Northwest National Lab. “One of the appeals for me is being able to control a process that is so complex. I’m always drawn to challenges.”

The most common method of creating ammonia was developed in Germany in 1909. Known as the Haber-Bosch process, the reaction requires intense pressure and heat, which in turn require energy to create. The nitrogen comes from the air, but the necessary hydrogen is often taken from natural gas in another process that releases carbon dioxide. Mock said that while ammonia itself is a clean fuel source, synthesizing it is energy intensive.

Mock, a synthetic inorganic chemist, is studying the fundamental reactions of this process. This includes creating catalysts to mediate this reaction and exploring new strategies to attach and remove the hydrogen atoms from the nitrogen atoms, such as chemical relays. His project “Molecular Catalysts to Control Dinitrogen Reduction and Ammonia Oxidation” was funded this fall by a three-year, $475,000 National Science Foundation grant.

“Energy storage and conversion is central to sustainable energy applications and is one of the overarching research themes of the Department of Chemistry and Biochemistry at MSU,” said department head Joan Broderick. “We are therefore delighted by Mike’s success and his plans for investigating reactions central to energy conversion.”

The grant includes funding for two graduate students. Mock will partner with the All Nations Alliance for Minority Participation to recruit an undergraduate student from a tribal college each summer for an internship to gain hands-on laboratory experience in chemistry and catalysis. He is also developing activities to engage students at area schools about alternative forms of energy.

Like most fundamental science, Mock said the value in this project lies in creating an understanding of how the process of converting nitrogen to ammonia and back works. Other scientists may then, someday, build on that knowledge for other uses, such as the machine he envisioned or commercial production.

“One day, someone can take this work we did and apply it to a more practical system for doing the same type of chemistry on a larger scale in an industrial setting,” Mock said.