Breaking ground and cracking ammonia


The 2013 pilot plant produced fertilizer that was sold to local farming cooperatives. Image: Cory Marquart

By Jake Christie

The University of Minnesota will break ground this fall on a plant that will produce ammonia with solar and wind energy.

The new plant improves on a pilot plant the university built in 2013, said Mike Reese, the renewable energy director for the University of Minnesota West Central Research and Outreach Center.

Producing ammonia from renewable energy is an important step in reducing two potent sources of greenhouse gases that cause global warming, he said.

Ammonia production is responsible for about 2% of global carbon dioxide. And ammonia based fertilizer is responsible for around 40% of carbon emissions in agriculture, Reese said.

Around 85% of ammonia is used in agriculture, according to the American Chemical Society. (Household ammonia is a water solution with about 5% to 10% pure ammonia, according to the United States Occupational Health and Safety Administration.)

Because most ammonia is produced in large amounts at relatively few locations, the fertilizer has to be shipped long distances, said Prodromos Daoutidis, a professor of chemical engineering and materials science at the University of Minnesota.

Producing ammonia with wind or solar power would shift the current process to more local distribution by allowing smaller amounts of fertilizer to be produced at county levels, Daoutidis said.

Fertilizer produced at local levels could reduce costs and carbon emissions related to transport, Reese said.

So-called “green” ammonia plants can harness wind and solar energy produced during off-peak consumption hours, Daoutidis said.

Ammonia synthesis is an energy intensive process, but new techniques will increase efficiency in the new plant. Image: Cory Marquart

By using green ammonia for fertilizer and as a fuel to dry crops, farmers could cut their carbon emissions by nearly 80%, Reese said.

Ammonia also offers a cheap alternative to batteries in terms of energy storage, Daoutidis said.

Energy storage is important to the transition from the fossil fuels that contribute to global warming.

Renewable energy is produced intermittently, often not in sync with the public’s needs, Daoutidis said. That means excess energy needs to be stored.

Because ammonia is made of hydrogen, and ammonia is easier to store than pure hydrogen, it can cut the cost of storing and transporting hydrogen, Daoutidis said.

Hydrogen stored via ammonia can be broken back down into hydrogen through a process called ammonia cracking, the hydrogen could then be used as an energy source, Daoutidis said.

Ammonia could also be used as fuel; the University of Minnesota has a tractor that runs on a mix of ammonia and diesel fuel, Reese said.

Ammonia needs to be mixed with diesel because the high temperature needed to ignite it can create Nitrogen oxides, a harmful greenhouse gas, Reese said. Ways to safely burn ammonia are being researched.

Development for the new plant started in 2021 with funds from the United States Department of Energy’s Advanced Research Projects Agency. The university received over $10 million from the Department of Energy’s REFUEL initiative, which funds projects aimed at converting air and water into liquid fuels.

The plant is planned to be operational in 2025, according to Reese.

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