A Plant in Florida Emits Vast Quantities of a Greenhouse Gas Nearly 300 Times More Potent Than Carbon Dioxide

Ten miles north of Pensacola, Florida, on the west bank of the Escambia River, an aging chemical plant, its tanks, smokestacks and stainless steel pipes sprawling across hundreds of acres, is a climate killer hiding in plain sight.

The plant, owned by Houston-based Ascend Performance Materials, makes adipic acid, one of two main ingredients for nylon 6,6, a strong, durable plastic used in everything from stockings to carpeting, seat belts and air bags. The plant also emits vast quantities of an unwanted byproduct, nitrous oxide, more colloquially known as “laughing gas.”

From a climate perspective, the plant’s emissions are no joke. Nitrous oxide, or N₂O, is nearly 300 times more potent than carbon dioxide as a greenhouse gas. N₂O emissions totaling 33,046 metric tons from the plant in 2018, the most recent year for which data is available, equal the annual greenhouse gas emissions of 2.1 million automobiles, according to company data reported to the Environmental Protection Agency and the agency’s greenhouse gas equivalencies calculator.

That is more than all the registered vehicles in Miami and nearly one-third of all cars in Florida. But unlike the carbon dioxide that spews from automobiles or smokestacks, nitrous oxide emissions from chemical plants can be abated using existing technology at relatively modest cost. 

The plant, a subsidiary of SK Capital Partners, a private equity firm that says it generates $9 billion in annual revenue, is the largest point source of nitrous oxide emissions in the country. Its number one ranking as a nitrous oxide polluter illustrates how companies often choose to leave untouched greenhouse gas emissions they aren’t required by law to abate, even when proven systems exist to eliminate those emissions. In the case of nitrous oxide emissions, DuPont and its global competitors, alarmed by N₂O’s potency as a greenhouse gas, joined forces almost 30 years ago and developed technologies to abate virtually all of their pollution.

The plant’s exceedingly high emissions persist at a time when climate scientists are increasingly calling for reductions of so-called super-pollutants, highly potent greenhouse gases like nitrous oxide that, on a per ton basis, cause far more warming of the atmosphere than carbon dioxide.

Nitrous oxide stays in the atmosphere for 114 years, longer than a human lifetime, yet shorter than the centuries that carbon dioxide can remain in the atmosphere.  

Even if all carbon dioxide emissions ceased today, the CO2  already in the atmosphere would continue warming the planet for centuries. Reducing nitrous oxide and other shorter-lived climate pollutants—some of which, like black carbon and tropospheric ozone, only remain in the atmosphere for a matter of days—would help combat climate change faster.

Ascend officials say they are aware of the problem. Vikram Gopal, Ascend’s senior vice president for technology, told InsideClimate News that Ascend will implement a process this year for reducing its nitrous oxide emissions by 50 percent. Additional new technology for further reductions would be in place within two years, he said.

Taking on Nitrous Oxide

A crystal globe rests atop a bookshelf in Ronald Reimer’s home office and guest bedroom in a Georgetown, Texas, retirement community. Reimer, 74, a former engineer for DuPont, received the award from the company in 1992 for leading a team of DuPont researchers in an international effort to reduce nitrous oxide emissions across the industry.  

Reimer first heard about the problem nitrous oxide posed to the planet in early 1991, when DuPont executives shared with him a study from the journal Science, warning about the potential impacts of nitrous oxide emissions from adipic acid plants on the “greenhouse effect” and ozone depletion.

“Because of the sheer volume of the industrial process, the long residence time of the gas in the atmosphere, and its accompanying consequences, the assumption that such emissions are harmless may be invalid,” the study concluded.

Even before the study came out, Reimer was trying to figure out a way to reuse all the nitrous oxide that the company was currently releasing at its plant in Orange, Texas. At the time, no one thought much about it. Nitrous oxide, the “laughing gas” commonly used by dentists, didn’t pose an immediate harm to human health. Other engineers at the plant would joke that DuPont was “just making everybody happier,” Reimer recalls.

The Science study got a lot of media attention, including a story in The New York Times. When company management caught wind of it, they asked Reimer what he thought.

“Obviously greenhouse gases trap heat and have the potential to increase global temperatures, it was pretty straightforward,” Reimer said, recalling the moment. “Our management bought it and they said, ‘OK, well, we’ll voluntarily abate it.  But we don’t want to do it unless we could get all the other major producers to do the same thing because it’s an expense.’”

An Unlikely Collaboration 

Five months after the Science study came out,  DuPont announced an inter-industry effort among six of the world’s leading adipic acid producers to solve their nitrous oxide emissions problem by the end of the decade.

Over the next two years, Reimer and representatives from each of the companies, including industry heavyweights BASF and Bayer in Germany and Asahi in Japan, met four times in Geneva, Switzerland, to share information and abatement technology.    

Reimer and his new-found collaborators, who under any other circumstance would be viewed as competitors, were attempting something that had never been done—and were doing it at breakneck speed.  

“It was audacious,” Charles Perilloux, a DuPont engineer who was not part of the initial collaboration but later worked on nitrous oxide abatement, said of the technology. 

One of the methods Reimer and his colleagues at DuPont pioneered broke nitrous oxide down for reformulation into nitric acid, a chemical used to make adipic acid, essentially recycling their waste gas into something they could reuse. For the process to work, the gas had to be heated to 800 degrees, a temperature at which point it begins to decompose, sometimes explosively. “That is a pretty extreme process,” Reimer said. 

DuPont licensed the technology to Rhône-Poulenc, a chemical company that made adipic acid in France, and pursued a less costly approach for its own plants. DuPont used a slightly different chemical reactor that simply broke N₂O down into nitrogen and oxygen, the two primary components of air, before releasing the gases into the atmosphere.

A photo Reimer kept from the time shows someone standing next to a reactor that had recently been completed, a few pixels of green and white at the base of six or more stories of steel tanks, pipes, and support beams. “I might be the guy actually standing there,” he says of the image.

DuPont located its chemical reactors at the three adipic acid plants it then owned in the United States and Canada, and began construction of them simultaneously, before the technology was fully vetted.

“Typically you would never commit to new technology at three sites without it having been proven at one,” Perilloux said. “This was not a typical approach.”

By 2000, all the companies were abating 90 to 98 percent of their total N₂O emissions. Nearly three decades later, Reimer recalls the collaboration as the highlight of his career.

“I saw myself working on something that had impact beyond our businesses,” Reimer said of the experience. Until the Geneva meetings with his international competitors, he had never traveled outside of North America. 

“It was something that I thought had global impact,” he said. “It was important environmentally and, in a more general sense, [more] than just improving the yield of a process.”

‘Low-Hanging Fruit’

Ascend’s adipic acid plant in Cantonment, Florida, was built in 1953 by Chemstrand Corporation, a company owned in part by Monsanto, a major adipic acid producer that did not take part in the DuPont-led collaboration. The plant is one of two adipic manufacturers in the country, and the largest in the world, according to Ascend.

Chemstrand sold the plant to Solutia, a Monsanto spin-off, in 1997. The companies had been working on a nitrous oxide fix of their own. Solutia said its process would abate 98 percent of its nitrous oxide while also recycling the gas into phenol, a plastics feedstock.

It was a more challenging process than those developed by DuPont, and one that Reimer says he doubted would ever work. By the late 1990s, market demand for phenol had dropped and Solutia never went forward with its abatement plan.

Twenty years later, Ascend, which purchased the Cantonment plant from Solutia in 2009, is still abating nitrous oxide at a lower rate than many of its competitors. 

The cost of such abatement at adipic acid plants, either through incineration or chemical breakdown, is approximately $3 or less per metric ton of carbon dioxide equivalent, according to a 2014 report by the Institute for Applied Ecology in Germany.

By comparison, retrofitting existing coal plants with carbon capture and storage technology would cost more than $80 per metric ton.

“It’s a very low hanging fruit, maybe one of the lowest,” said Lambert Schneider, research coordinator for international climate policy at the Institute for Applied Ecology and lead author of the Institute’s 2014 report, referring to abating nitrous oxide. “The cost is extremely low compared to other mitigation options,” he said.

Ascend uses a “thermal reduction unit” or incinerator to destroy nitrogen oxides (NO_X), pollutants that contribute to smog and acid rain and are closely regulated under the Clean Air Act. As an added benefit, the process also destroys  emissions of (N₂O), the greenhouse gas. Without this incineration, greenhouse gas emissions from the plant would exceed the annual emissions from all the cars in Florida.

But the incinerator doesn’t eliminate all the plant’s NO_X  and as production at the plant increases, the company bumps up against their federally permitted NO_X emissions limit. When this happens, plant operators have to switch from incinceration to a different system that uses chemical catalysts to treat their emissions.

This backup system, known as “selective catalytic reduction” does a better job of abating NO_X,  but it does not destroy N₂O.

“There can be a trade-off between N₂O abatement and abating other potentially harmful pollutants such as NO_X,”  a recent description of Ascend’s abatement technology written by a company representing Ascend states. “Because N₂O is not regulated and NO_X emissions are regulated under the Clean Air Act,”  plants will only use their incinerators when they are not in danger of exceeding their NO_X limits.

The end result is that when production at the plant increases, nitrous oxide emissions soar. This is exactly what happened at the plant from 2015 to 2018.  As adipic acid output from the factory increased, N₂O emissions tripled, from 3 million tons of CO2 equivalent to 9.8 million tons of CO2 equivalent, according to data the company reported to the EPA. Over the same four-year period, the percent of nitrous oxide emissions that the plant abated  dropped from 91 percent to 75 percent.

Gopal, Ascend’s senior vice president for technology, said efforts already underway will  reduce the plant’s current emissions by 50 percent by the end of the second quarter. 

Gopal said the company has been working on another approach over the last five years that will recycle nitrous oxide back into nitric acid and should be implemented in 18 to 24 months.  

While the cost of abating nitrous oxide may be low compared to abating other forms of  carbon emissions, it is not insignificant, especially when pursuing the more complex recycling technology. Ascend would likely have to spend tens of millions of dollars to significantly reduce its nitrous oxide emissions.

Gopal stressed that the company is doing the work voluntarily and that it had historically focused on making sure it met emissions limits for regulated pollutants, including NO_X, the ozone and acid rain-forming substance.

Ascend’s adipic acid plant has been out of compliance with the Clean Air Act for six of the past 12 quarters for various pollutants including NO_X, according to the EPA. The plant’s non-compliant emissions appear to be relatively small, involving short term releases across the sprawling, aging facility, rather than persistent, systemic emissions that far exceed permitted levels.

“At the end of the day, you have to make sure you run your plant in a way that is compliant,” Gopal said.

Ascend Believes Its New Technology Will Cut Emission by 95 Percent

As it navigates a future in which climate change becomes an ever more potent political issue, Ascend is not only developing its new abatement technology, but hoping it can produce credits to be sold as offsets to other corporations looking to deal with their own greenhouse gas emissions.

The company denied a request to tour the facility and view the ongoing  N₂O abatement pilot projects. A 2019 company patent, however, provides more details on the chemical reactor they are developing that would allow for nitrous oxide to be recycled back into nitric acid.

“Five years ago we decided to come up with a better solution, not because we were obligated to do so from a regulatory standpoint, but because we believed we could develop a technology that would reduce our emissions and recycle what was waste into a useful material,” Alison Jahn, a spokeswoman for the company, told InsideClimate News.

Gopal said Ascend will be the “first in the world” to do something “very different” from what others have done before.

The proposed chemical reactor, however, appears similar to the one Reimer and others at DuPont developed and licensed in the 1990s that allows for nitrous oxide to be recycled back into nitric acid. 

It does make a few modifications that could allow for some additional recycling of nitrous oxide into nitric acid but, “honestly, I think it’s reinventing the wheel,” Reimer said of Ascend’s patent.

Gopal disagreed, saying the older technologies “are good, however they are low conversion processes, where the recovery of useful products is small. We have a process which enables a significant improvement in the overall system footprint.”

If Ascend pursued existing technology through a licensing agreement rather than developing its own solution in house, it’s likely the company could have already significantly reduced its nitrous oxide emissions, Reimer said. There are, however, often legal advantages to owning the patents for the reactors you operate, he added.

Costs for new nitrous oxide abatement technology pursued in the 1990s averaged around $10 million per plant, according to a peer-reviewed study Reimer and others published in 2000. Inflation, as well as the more complex nature of Ascend’s recycling approach, would probably result in significantly higher costs.

As Ascend develops its abatement technology, the company is working to develop “voluntary offset credits” for any additional  nitrous oxide emissions reductions it achieves with the new technology. If Ascend succeeds in setting up the proper trading protocol, it could then sell those credits to others looking to offset their own greenhouse gas emissions.

Jahn said the potential for Ascend to sell offsets for its emissions reductions doesn’t affect the company’s decision to move forward on its new abatement technologies. She declined to comment on how the sale of such credits would compare to the added capital investments needed to further abate nitrous oxide.

Such credits come with a lot of uncertainty due to fluctuating markets—carbon markets have recently experienced steep declines along with financial markets as a result of the coronavirus pandemic—and government regulations. While the current administration is unlikely to place federal regulations on nitrous oxide, a future administration could. If nitrous oxide emissions were regulated, sales of emission credits would cease as soon as the regulations were implemented, according to the current draft of the proposed crediting system.

Gopal said the new abatement technology would allow Ascend to eliminate more than 95 percent of its nitrous oxide emissions. That level of abatement would bring it in line with the low levels of nitrous oxide emissions that most other plants in the United States and Europe attained in the 1990s.

Over the past 20 years, however, global adipic acid production has shifted increasingly to China, where it appears that some plants that now compete with Ascend in a global market may not abate at all.

“We’ve got to do something about it,” Gopal said of his company’s nitrous oxide emissions.  But, he added, “you have to find a way that these processes are economically viable.”