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  • Writer's pictureAllan Dyen-Shapiro


From time to time, I see an environmental science story where sufficient details are missing to make it unintelligible or, more often, in-actionable. A communication gap between scientist and journalist or between journalist and activist can be a reason why nothing changes. I think I saw such a case today.

Here’s the headline: twelve adipic acid plants, eleven in China and one in Florida, emit enough nitrous oxide, a highly potent greenhouse gas, to be equivalent to the greenhouse gas emissions of 31 million cars. Here’s the claim: the fixes needed to prevent these emissions are simple and cheap. So, why haven’t they happened? Also, is the question framed appropriately?

It took following a few links to find out what cheap meant. (I’ll put the important ones at the bottom of this post—warning, an important figure in one is mislabeled—along with all the other links I used). 83% of adipic acid is used for polymerization into nylon 6,6; another 8% is used to make polyurethane. 65% of nylon 6,6 goes into making cars and other light vehicles; 40% of polyurethane goes into making mattresses. Passing on all costs to the consumer would raise the price of an automobile by forty cents; mattress costs would go up by one percent. Okay, cheap, I’ll accept this.

As far as relevant to world benefits, on an annual basis, that is. I’d argue this phrasing misses the problem. The key metric to consider is what upgrading one of these plants would cost. The world currently has only 39 adipic acid plants, and we are talking about only twelve of them. (Europe, Japan, and South Korea mandate these technologies, and even in the US and China, which don’t, some plants use them anyway.) It took $1.3 billion supplied to China by a UN program at the beginning of this century to upgrade all of their pollution controls on adipic acid plants. The program ended in 2012; some of the Chinese plants stopped using the pollution controls. Do they still work? I doubt it.

Chinese scientists are on the record urging their government to do something about this problem. To date, unsuccessfully.

The Ascend Performance Materials plant in Cantonment, Florida (on the Alabama border fifty miles east of Mobile) has never had these controls. The articles I found said that instituting a heating step (nitrous oxide will decompose at high temperatures) and a catalytic step (where a chemical catalyst breaks it down) together will reduce emissions by greater than 99%. Either upgrade is about $3.9 million, so let’s round it off to $8 million to upgrade this plant. This isn’t a trivial amount of money for one plant operator to swallow as a cost.

The Florida Panhandle is one of the most politically conservative areas of the country. Trust me; there will be no local grassroots movement demanding these changes.

As for county tax abatement, this privately-held company already pays no taxes at all and will for a seven-year period ending in 2024. The $160 million in public funds is going for upgrades to their 50-year-old facility. Apparently, these upgrades are primarily for efficiency, staying cost-competitive, and were billed as saving five hundred jobs.

You can’t incentivize a company that already pays no taxes with tax credits. As for state taxes, in 2021, Governor DeSantis reduced the corporate tax rate from 5.5% to 3.535%. The company’s annual revenue was $2.1 billion in 2022, and if we take the fraction of their total workforce based in Florida (500/3100) as a proxy for income from this plant and multiply that by the tax rate, we get $12 million. And that’s if they paid the full tax rate on every nickel they made with no deals, offsets, or credits, and you know that’s never the case. So, let’s take a conservative guess and say the company pays Florida $5 million in taxes each year. Canceling all state taxes for a couple of years would likely be sufficient incentive if and only if there was also a law forcing them to comply. In Florida, with a Republican supermajority in the legislature, this isn’t happening, especially on an issue like climate change, which many of these politicians will still claim is a lie.

As for Global Efficiency Intelligence, the authors of the report that alerted the world to the twelve super-polluters? They aren’t activists; they are corporate consultants based in Tampa. Their milquetoast recipe for getting even cheap pollution controls implemented: “Conducting an awareness campaign through the key players and manufacturers of the automotive industry can support the installation and operation of the N2O emissions abatement technologies in their supply chain in the adipic acid facilities.” The major auto companies of the world are going to pressure plant owners in an ultraconservative area of Florida (and in China!!!), and that’s going to cause them to spend their own money to adopt green technology voluntarily.

Good luck with this.

On the other hand, if Joe Biden put that $8 million into the federal budget (perhaps as a tax credit, so it could be invisible in a way that gets things through Republican obstructionism) and then had the EPA use its authority under the Clean Air Act to mandate usage of the money, it might happen. He could talk it up publicly and sell it to the Florida Congressional delegation as a giveaway to Florida (which it would be). As such, the key barrier to this is getting Joe Biden to notice the issue and care about it.

It might be doable. However, that raises the second issue: are we even asking the right question? I dug deep in my memory to recall conversations with DuPont Corporation scientists around the turn of the Millennium when I was faculty at the University of Delaware. They were working on getting bacteria to produce adipic acid. They put glucose into a fermenter, and their genetically engineered bacteria made adipic acid. Back then, it wasn’t about climate. DuPont invented nylon and made a lot of nylon. Adipic acid cost money. They wanted a cheaper process. Had their entire research operation in Delaware not closed down (with the two-century-old company disappearing), they probably would have had it by now.

Even then, there was an environmental angle to the work. Conventional production of adipic acid uses benzene (a serious carcinogen) derived from petroleum. Replacing fossil fuels with biology was a huge mantra for DuPont back then. However, with no company proud of their nylon research replacing DuPont, there was also no company pushing the federal government to fund research at universities into adipic acid fermentation technologies. As such, research plodded ahead at a much slower pace than it would have. I have found numerous papers that say complete biological synthesis of adipic acid (in several different types of bacteria or recombinant yeast) is now way cheaper than full chemical synthesis. So, we’re back to start-up costs of building plants from scratch or repurposing fermenters from existing projects. Not a fortune, but not something a company will do without either a guaranteed market, tax incentives, or direct payments from government.

Again, time to call Joe Biden. But also call the journalists: not a single one of the articles I found on the report on the twelve super-polluter plants mentioned the bio-based synthesis alternative.

So, let’s say you’re an activist reading this, and I’ve convinced you to take on the project of raising this issue’s political profile. Every single one of these articles lacked the answer to a pretty important question: why does full-chemical adipic acid production make nitrous oxide, and why doesn’t full-biological synthesis make it?

Adipic acid is a six-carbon chain (hexane) with a carboxylic acid group on each end. The former is carbon and hydrogen atoms; the latter is carbon and oxygen. The nitrogen for the nitrous oxide comes from an intermediate step. In the full-chemical synthesis, benzene (a ring of six carbon atoms connected by three double bonds, with the electrons making a ring above and below the carbon hexagon) is first converted to cyclohexane (no double bonds, just a ring of six carbon atoms with hydrogen still attached to each). In the second step, the cyclohexane is converted to KA (ketone alcohol) oil, which is a mix of cyclohexanol (which has an alcohol group—oxygen and hydrogen—attached to one of the carbons) and cyclohexanone (which has one of the carbons double-bonded to an oxygen atom). So far, no nitrogen atoms, but in the third step, the KA oil is reacted with nitric oxide (which does have nitrogen) in the presence of air. Nitric oxide removes an electron from the KA oil, becoming nitrous oxide, the major byproduct.

Moreover, nitric oxide is itself problematic for the climate, being made from—you guessed it—fossil fuels. Methane (a fossil fuel) is used in the production of ammonia, which is reacted at high temperatures (reached by burning fossil fuels) to produce nitric acid. This reaction produces copious nitrous oxide (!!!) as a byproduct. (The nitric acid is then reacted with sulfur dioxide to make nitric oxide.)

Biological production avoids all of these sources of nitrous oxide because nitric oxide is not what a living system uses as an oxidant, and the precursor of biological adipic acid is not a fossil fuel. The biochemistry is complicated and there are many different possible pathways to adipic acid, so I’ll just put some links below for the aficionados.

One last request for the climate justice folks reading this: after you sell your buddy Joe Biden on the greening of adipic acid production, ask him to whisper in Xi Jinping’s ear that China should do the same. There aren’t likely to be any other problems to get in the way of Sino-American cooperation on this issue. It’s not like there’s a trade dispute or various sorts of saber-rattling going on.

Yeah, right. I’m not getting my hopes up.

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