Renewable Nitrogen Fertilizer Production

By Ted Aulich
U.S. agriculture is dependent on nitrogen-based fertilizers, and the U.S. fertilizer industry is dependent on natural gas as the primary source of hydrogen for reaction with nitrogen to yield ammonia. In 2003, more than 50 percent of U.S. ammonia was produced in Louisiana, Oklahoma, and Texas because of their large reserves of natural gas. Also in 2003, U.S. producers were second behind China in the production and consumption of ammonia, 90 percent of which was used for fertilizer. A fertilizer in its own right, ammonia is also the feedstock for production of urea, ammonium nitrate and other nitrogen fertilizers.

The cost of domestic natural gas typically accounts for at least 80 percent of the cost of ammonia-and by extension, the cost of all other nitrogen-based fertilizers. The volatile and high prices of domestic natural gas have resulted in a significant increase in fertilizer imports and a significant reduction in U.S. fertilizer production capacity.

One way to ensure against overdependence on imported fertilizer is to develop domestic fertilizer production capabilities in noncoastal regions that can compete with current import-based scenarios. Import-based fertilizer production includes the use of low-cost "stranded" natural gas; large-scale ammonia production via the high-pressure, high-temperature Haber Bosch process; and long-range transport to U.S. farmers.

The Energy & Environmental Research Center at the University of North Dakota recently developed an electrolytic ammonia production process that replaces high-cost, high-purity hydrogen from natural gas with lower-cost mixtures of hydrogen and carbon monoxide derived from biomass gasification. Because it is driven by electricity and operates at significantly milder conditions than the Haber Bosch process, the EERC process offers the potential to directly utilize wind-generated electricity for ammonia production at significantly reduced capital and operating costs versus the Haber Bosch process.

In partnership with the North Dakota Corn Utilization Council, the Minnesota Corn Research and Promotion Council and the EERC Foundation, the EERC is developing the electrolytic ammonia production process for commercial applications. Progress to date includes development of a highly active and durable catalyst that enables ammonia production at ambient pressure and a temperature of 200 degrees Celsius (392 degrees Fahrenheit) versus typical Haber Bosch conditions of 3,000 pounds per square inch and 450 degrees C (842 degrees F). These milder process conditions translate to significantly reduced capital and operational costs, which will enable commercial production at smaller, more distributed scales than currently required for commercial viability. Distributed-scale production means that plants could be located closer to the farmland where it is being applied, drastically cutting transportation costs.

Based on progress made to date, the EERC is targeting an ammonia production cost of $300 per ton. Once the technology is fully commercially competitive, ammonia production targets would result in lower-cost fertilizer; support domestic fertilizer production; enable extracting value from wind energy without the need for major expansion of expensive, difficult-to-permit transmission capacity; provide a means to potentially lower the carbon footprint of ammonia production using renewable power and feedstocks; and promote rural economic development on the wind- and agriculture-rich Great Plains.

Ted Aulich is a senior research manager at the EERC. Reach him at [email protected] or (701) 777-2982.