The process of creating fertilizer out of natural gas could literally be described as pulling nitrogen out of the air.

The CHS nitrogen fertilizer plant construction was officially announced on Friday. Brian Schouvieller, CHS senior vice president of North American grain marketing and crop nutrients, said 88,000 MMBtu of natural gas will be fed into the plant via pipeline to produce 2,400 tons of ammonia a day. One MMbtu is equal to 1 million British thermal units (Btu), and one Btu is the heat required to raise the temperature of one pound of water by one degree Fahrenheit.

Schouvieller said natural gas will be the sole source of hydrogen for the plant. The natural gas enters a chamber with regular air, which contains about 78 percent nitrogen. The gases then undergo the Haber-Bosch process, named for the Nobel Prize-winning scientists who developed the process.

The Haber-Bosch process raises the temperature of the chamber to 572 to 1,022 degrees and increases the air pressure to a range of 2,200 to 3,600 pounds per square inch (psi). In comparison, the average psi at sea level on Earth is about 14.7 psi.

The chemical reaction in the chamber produces ammonia out of the nitrogen and hydrogen, and ammonia is the main ingredient in nitrogen fertilizers. The gases that don’t produce ammonia on the first pass are recycled again through the tank.

“It (the ammonia) is further processed into urea and then the urea is further processed into UAN,” Schouvieller said.

UAN is a solution of urea and ammonium nitrate in water which becomes fertilizer. The ammonia will also be used to produce diesel exhaust fluid, used in cleaning diesel engines.

“It (UAN) is a nitric acid, so basically they take the urea liquor and add water, and now you have a liquid that’s 28 percent nitrogen,” Schouvieller said. “It’s probably important to point out that ammonia is 82 percent nitrogen and urea is 34 percent.”

CHS engineer Bart Gill, project director for the Spiritwood plant, said CHS wants to use as many U.S. manufacturers for components needed for the plant, but some of the parts it needs will have to be imported from Europe. Several of the components are very large, including a 500-ton ammonia converter.

“That’s the largest single piece of equipment that we’ll have, but we have several pieces of what we call oversized-overweight equipment that we’re going to have to transport into the site,” Gill said. “They’ll be moved first on the ocean, probably over to the port of Duluth, then transported by roads and/or rail if we can get rail, but more likely by road now to the site.”

Sun reporter David Luessen can be reached at 701-952-8455 or by email at

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