They develop a new way to calculate the environmental impact of ammonia production

Ever wonder about the carbon impact of growing your dinner? Scientists have just come up with a new way to calculate some of it.

A main ingredient in the production of fertilizers for global food production, ammonia also contributes significantly to the world’s greenhouse gas emissions and fossil fuel use. Recently, scientists at the US Department of Energy’s (DOE) Argonne National Laboratory have modeled how much it would cost to use greener, less carbon-emitting methods to produce ammonia.

Ammonia is produced primarily by reforming natural gas, a process that contributes to atmospheric emissions of both carbon dioxide and methane. “The ultimate goal is to use renewable or nuclear energy and clean hydrogen to produce it,” said Argonne Principal Scientist Amgad Elgowainy.

Elgowainy and colleagues used Argonne’s Greenhouse Gas, Regulated Emissions, and Energy Use in Technologies (GREET®) model to estimate the environmental impact of ammonia production from various energy sources. They then used a techno-economic model to analyze the cost of two different ways to produce ammonia more sustainably.

The first way avoids part of the carbon release by capturing a certain percentage of the carbon produced and then storing it in geological formations. This technological path can be implemented at a relatively low cost, since the total cost to produce the ammonia increases only about 20%.

In the other near-zero carbon route, water is electrolyzed to produce hydrogen, which then combines with nitrogen to produce ammonia. “Using renewable or nuclear energy to split water through electrolysis gives us a way to produce ammonia with almost no carbon footprint,” Elgowainy said. “That said, the cost of doing it is currently higher than the carbon capture pathway.”

According to Elgowainy, there is significant scope for electrolysis technology cost reduction that could eventually make the water electrolysis route more cost competitive. “Research in this area could end up changing the market significantly, but it will require investment to develop and scale-up production of electrolysis technologies,” she said. “With cost reductions and efficiency improvements to meet DOE’s goal of $1/kg clean hydrogen, the electrolysis pathway could enable an affordable, nearly carbon-free way to produce ammonia.”

Reference: Lee K, Liu X, Vyawahare P, Sun P, Elgowainy A, Wang M. Technoeconomic performance and life cycle greenhouse gas emissions of various ammonia production pathways, including conventional, carbon capture, nuclear and renewable energy. green chemistry. 2022;24(12):4830-4844. doi:10.1039/D2GC00843B

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