Agrebon to install biogas-to-nitrogen technology at ethanol plant

By Sue Retka Schill | April 08, 2013

Project development is in the financing stage for a nitrogen fertilizer facility to be co-located with Tharaldson Ethanol Inc., a 153 MMgy facility located in Casselton, N.D. The fertilizer plant would produce urea, anhydrous ammonia and UAN (urea ammonium nitrate) from biogas produced from ethanol stillage.

Scott Dyer, chief science officer and co-owner of Colorado-based Agrebon Inc., said an agreement with business development partner, Progressive Nutrient Systems, is in place and the agreement with Tharaldson is near completion. North Dakota-based Leading Edge Angel Fund LLC is in the process of raising equity funds, to supplement local investment. If all proceeds as expected, the project could break ground by midsummer and due to the use of prefabricated components, be operational six months later.

The distributed fertilizer production process developed by Agrebon utilizes well-known technology from the large-scale production of nitrogen from natural gas, substituting biogas produced in an anaerobic digester. The challenge has been to downsize the technology to match the available biogas resource. “We’re creating nitrogen out of the ethanol plant’s stillage, removing the insolubles and oil through an anaerobic digester to make biogas and returning the water as backset with only the minerals remaining,” Dyer explained. The biogas is then processed on-site into nitrogen, some of which goes back to the ethanol process as yeast nutrients.

For every 25 MMgy of ethanol produced, the Agrebon system is able to produce 11.5 million pounds of nitrogen, Dyer continued. “Which is roughly 1 pound of nitrogen for every bushel of corn used and removes that carbon footprint,” he said. Dyer also points out that reducing the carbon footprint is going to become important for corn ethanol producers wanting to add incremental gallons. While their current production was grandfathered in under the revised renewable fuel standard, new gallons must meet greenhouse gas reduction thresholds.

Agrebon and Progressive Nutrient Systems expect the fertilizer products to be cost competitive, largely due to the local production model which eliminates shipping costs. The market radius for nitrogen produced in the facility will nearly match the corn supply radius for the ethanol facility, he added.

Pilot scale testing, economic modeling of the process, and an engineering review were done at the University of North Dakota’s Energy and Environmental Research Center, Dyer said. “Making ammonia is a technology that has been around for 110 years. The challenge in what we’re doing is that the equipment is sized for very large production volumes,” he explained.  In contrast the sheer size of the facilities used to make nitrogen fertilizer from natural gas, he said, “we’re going to be making 20 tons of ammonia a day and 35 tons of urea. Effectively, that is a pilot.” Tharaldson Ethanol already has an unused anaerobic digester on site, Dyer added. The 7,000-square-foot fertilizer facility will require about a 2-acre footprint.