When coal- and natural gas–fed plants produce ammonia, they generate two main by-products: heat and carbon dioxide (CO2).
The amount of heat released depends on which specific processes are used; most of it is captured and reused in the conversion process, reducing the amount of energy required by the plants for fuel. But even high-efficiency ammonia plants are heavy CO2 emitters: two tons are released for every ton of ammonia produced. A portion of the carbon dioxide is captured and used to produce urea (CH4N2O), the most widely used nitrogen fertilizer worldwide. But ammonia plants also produce anhydrous ammonia, ammonium nitrate (the compound that caused last week’s explosion in Texas), ammonium sulfate, UAN (urea ammonium nitrate solution) and other forms of ammonia used in agricultural and industrial applications—none of which use the leftover CO2. The rest is simply vented to the atmosphere.
In 2011 U.S. ammonia-producing facilities released 25 million tons of greenhouse gases (nearly all of it CO2)—just under 14 percent of the chemical-manufacturing sector’s total carbon footprint (and about 0.1 percent of total U.S. emissions). Globally, ammonia production represents as much as 3 to 5 percent of carbon emissions, according to some industry sources. And that doesn’t take into account the supply chain of natural gas production, energy-related emissions in the production process, fertilizer application (and misapplication) or industrial use of urea and other ammonia products.
This larger footprint is something many are concerned about, particularly as the industry expands. Glen Buckley, an industry consultant at NPK Fertilizer Advisory Services (and former chief economist at U.S. fertilizer giant CF Industries), estimates that only about six million tons of the proposed U.S. capacity will actually get funding and get built—still, that’s a more than 50 percent increase in total ammonia capacity nationwide. Whereas the U.S. accounts for just 6 percent of global ammonia production, currently, the majority of new plants are coming online here, or in Canada, which has also benefited from the natural gas boom.
This growth will be accompanied by a directly proportional rise in greenhouse gas. With six million tons of new ammonia production, U.S.-based emissions would increase to a minimum of 37 million tons. If more of the proposed plants get built, the total could reach as high as 50 million tons. Globally, ammonia production already accounts for 3-5 percent of total carbon emissions, according to some sources. Again, that’s not accounting for emissions upstream or downstream in the supply chain.
And it’s those concerns that have some watchers looking to the future.
On the upstream side, emissions concerns could slow supply or drive up costs through increased regulation—especially if the U.S. Environmental Protection Agency cries foul on the enormous amounts of gas flared from the production fields. “The EPA is a major wild card,” Buckley says.
But the downstream side could play a role as well. Jack Oswald, chairman and CEO of California-based SynGest, says there’s growing concern among consumer products companies about carbon in their supply chains. Instead of natural gas, SynGest is proposing to use a biomass gasification process in its ammonia production plants.
Among Oswald’s backers are forest product and packaged food companies starting to take a look at their products’ carbon footprints. He provides the example of orange juice manufacturers he’s spoken with in the southern U.S.: “Transportation turns out to be a small piece. Approximately 30 to 33 percent of their carbon emissions is associated entirely with the nitrogen fertilizer.”