Image: On a pound-for-pound basis, N2O is 273 times more potent as a greenhouse gas than carbon dioxide, the primary driver of climate change. (from Climate Central)

Eleven Chemical Plants in China and One in the U.S. Emit a Climate Super-Pollutant Called Nitrous Oxide That’s 273 Times More Potent Than Carbon Dioxide

Proven, low-cost pollution controls could quickly curb those emissions, but neither China nor the U.S. require abatement measures used by other plants around the world.

Twelve chemical plants in China and the United States emit a potent climate pollutant with collective emissions equal to the annual greenhouse gas emissions of 31 million automobiles, according to a report published on Thursday by Global Efficiency Intelligence, an industrial decarbonization research and consulting firm based in Tampa.

The emissions, which also deplete the earth’s protective ozone layer, could be effectively eliminated at little cost, the report’s authors conclude.

The 11 Chinese plants and one U.S. plant emit a combined, estimated total of approximately 500,000 metric tons of nitrous oxide (N2O), according to the report. On a pound-for-pound basis, N2O is 273 times more potent as a greenhouse gas than carbon dioxide, the primary driver of climate change.

The gas is an unwanted byproduct in the production of adipic acid, a key ingredient in nylon 6,6, a highly durable plastic used in airbags and car tires. Nitrous oxide emissions are also the leading, ongoing source of atmosphere ozone depletion after more harmful chemicals were banned in recent decades under the Montreal Protocol, an international environmental agreement.

The plants’ N2O emissions could be reduced by 98 percent or more at little cost through proven pollution control technologies that other adipic acid plants in the U.S., Europe and Asia have used for decades, according to the report.

“Adipic acid is this small corner of the industrial sector and it has a huge and outsized impact on climate,” said Evan Gillespie, who reviewed an early draft of the report and is a partner with Industrious Labs, an environmental organization working to decarbonize heavy industry. “The opportunity to address the climate emissions are cheap, they’re fast, they’re easy, and they’re necessary,” he said.

The report estimated that producing enough nylon 6,6 for the tires, airbags, carseats and other components of a typical passenger vehicle results in the release of nitrous oxide equal to 976 kilograms of carbon dioxide. The figure exceeds the greenhouse gas emissions associated with the production of the amount of steel used in the average passenger vehicle—900 kilograms—based on the emissions intensity of U.S. steel.

Eliminating the vast majority of nitrous oxide emissions from adipic acid production would add just $0.40 to the cost of a passenger vehicle, according to the report.

The combined, 2021 nitrous oxide emissions estimate provided in the current report from the Chinese and U.S. plants is slightly higher than a pair of assessments by Inside Climate News in 2020 of the same plants in China and the U.S. and reflect a slight growth in adipic acid production.

Emissions from the plants are on track to nearly double by 2050, based on anticipated industry growth in China, the report found. The U.S. plant, owned and operated by Ascend Performance Materials in Cantonment, Florida, “is operating only minimal levels of N2O emissions control well below the performance of European, Japanese, or South Korean plants,” according to the report.  Neither the U.S. nor China require adipic acid manufacturers to reduce their nitrous oxide emissions.

Ascend did not respond to multiple requests for comment. The company has begun to reduce emissions from its adipic acid plant andsell carbon offset credits on a voluntary market for its emissions reductions. The Florida plant released 24,655 tons of nitrous oxide in 2021, the most recent year for which data is available, according toemissions the company self-reported to EPA. The plant’s nitrous oxide emissions are four times higher than any other industrial facility in the U.S., according to the EPA’s Greenhouse Gas Reporting Program.

In the early 2000s, Chinese manufacturers received incentives through a U.N. program that were worth as much as $1.3 billion to install pollution controls and destroy nitrous oxide emissions. The lucrative incentive program had the unintended effect of driving a sharp increase in adipic acid production in China.

Funding for the program largely ceased in 2012 and, as a result, Chinese manufacturers likely stopped using their pollution control systems soon after.  However, at least one adipic acid plant in Chinahas taken measures to reduce its emissions in recent years.

In an opinion piece published last year in the journal Environmental Science and Technology, researchers from Zhejiang University, in Hangzhou, called for new incentives for adipic acid manufacturers in China to abate their nitrous oxide emissions.

Gillespie, of Industrious Labs, said regulators in the U.S. and China should require adipic acid producers to reduce nitrous oxide emissions.

“It’s wild that you have a super-pollutant that is not regulated by the U.S. government,” Gillespie said.  “EPA could show more leadership here by regulating N2O emissions and specifically by looking at ways to require Ascend to abate their emissions in a consistent and permanent basis.”

The EPA did not immediately respond to questions about potential nitrous oxide emissions regulations.

Phil McKenna

Reporter, Boston

Phil McKenna is a Boston-based reporter for Inside Climate News. Before joining ICN in 2016, he was a freelance writer covering energy and the environment for publications including The New York Times, Smithsonian, Audubon and WIRED. Uprising, a story he wrote about gas leaks under U.S. cities, won the AAAS Kavli Science Journalism Award and the 2014 NASW Science in Society Award. Phil has a master’s degree in science writing from the Massachusetts Institute of Technology and was an Environmental Journalism Fellow at Middlebury College.