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Aluminum plants in the U.S. are releasing tons of a highly potent greenhouse gas, unlike their counterparts abroad

A Century Aluminum plant in Kentucky and a recently closed Alcoa plant in Washington emit far more PFCs per ton of aluminum than Icelandic plants run by the same companies, according to an Inside Climate News analysis.
Photo illustration of an aluminum plant, a large smoke stack emitting fumes, and aluminum soda cans.
The U.S. aluminum industry needs revitalization, environmental advocates say, even as it has declined precipitously in recent decades. Chelsea Stahl / NBC News; Getty Images

This article was published in partnership with Inside Climate News, a nonprofit, independent news outlet that covers climate, energy and the environment.

ROBARDS, Ky. — Shielded by protective hoods and covered by a hard outer crust, giant pots brimming with molten aluminum bubble gently in a series of long, metal buildings here that make up the smelter Century Aluminum Sebree. This is one of the country’s largest sources of a potent greenhouse gas that remains in the atmosphere for 50,000 years, tetrafluoromethane (CF4).

In 2021, this aluminum plant vented 23 tons of CF4 as well as a ton of hexafluoroethane — both are perfluorocarbons, or PFCs, that are among the most potent and longest-lasting greenhouse gases on the planet, according to the U.S. Environmental Protection Agency. The pollution equals the annual greenhouse gas emissions of 40,000 automobiles, ones that will effectively remain on the metaphorical road for tens of thousands of years.

Meanwhile, a newer plant also owned and operated by Century Aluminum in Grundartangi, Iceland, emits just one-sixth the PFC emissions per ton of aluminum  compared to the company’s Sebree plant, according to an Inside Climate News assessment of EPA data, as well as financial and environmental reports published by Century and Nordural, its Icelandic subsidiary.

Operations At Century Aluminum's Smelter In Western Kentucky
A plant worker uses a crane to lift a cask of molten aluminum at Century Aluminum Company plant in Hawesville, Ky. in 2017. Luke Sharrett / The Washington Post via Getty Images file

It’s a tale of two smelters: older U.S. plants with some of the highest PFC emissions rates in the world and their overseas counterparts with far lower emissions — even when they are operated by the same multinational companies. The contrast highlights why the U.S. aluminum industry needs revitalization, environmental advocates say, even as it has declined precipitously in recent decades.  

“They’re a shell of what they used to be, but that doesn’t mean they are allowed to be a huge polluter, just because they’re old,” said Nadia Steinzor, a policy and research consultant with the Environmental Integrity Project in Washington, D.C. “If there are technological fixes that the industry can employ to lower or eliminate climate emissions, they should be required to adopt them.”

In a case similar to that of Century Aluminum, Alcoa’s Intalco smelter in Ferndale, Washington, emitted nearly 50 tons of PFCs in 2020 before the company temporarily shut down production that same year, according to the EPA. 

That’s in contrast to Alcoa’s Fjarðaál smelter in Fjarðabyggð, Iceland, which has a PFC emissions intensity less than one-fortieth that of the recently shuttered Intalco smelter, according to an Inside Climate News assessment of EPA data; the company’s production data, which was obtained through a public records request; and data the company publishes for its facility in Iceland.

Jim Beck, a spokesperson for Alcoa, said “we do not disagree” with the assessment. Beck added that emissions from the Intalco facility were high “due to the older technology and operational instability that the facility was experiencing.”

Century Aluminum offered a similar explanation for its Sebree plant, the largest U.S. aluminum production facility operating at full capacity, which was completed in 1973. 

“It is important to note that the Iceland facility is a newer and more technologically advanced” facility, Steinunn Dögg Steinsen, the vice president of health safety and environment for Century Aluminum, said in an email. Steinsen added that the smelting process at the plant in Iceland is more automated, resulting in more efficient production, while the Sebree plant relies more on manual controls, which are less precise. “This explains most of the difference in PFC emission between the plants,” she said.   

A Century Aluminum Sebree plant
The Century Aluminum Company plant in Sebree, Ky.Phil McKenna/NBC News

Although they are considered nontoxic by the U.S. Occupational Safety and Health Administration, CF4 and hexafluoroethane belong to a class of synthetic, fluorine-containing chemicals known as “the immortals” because of how long they remain in the atmosphere. Once the gases are released, they are “essentially permanent additions to the atmosphere” and threaten “the public health and welfare of current and future generations,” the EPA notes.

However, unlike carbon dioxide, the primary driver of climate change, the EPA does not regulate PFCs.

American aluminum vs. Chinese aluminum   

Twenty years ago, the U.S. led the world in aluminum production and in a worldwide effort to reduce PFCs, greenhouse gases that, pound for pound, are thousands of times worse for the climate than carbon dioxide, according to the UN’s Intergovernmental Panel on Climate Change. Now, just 1.5% of global aluminum smelting, or production, takes place in the U.S. — but efforts to reduce PFC emissions in the U.S. have stalled, according to an Inside Climate News assessment of EPA data, while the cleanest smelters in other countries have brought emissions of the potent greenhouse gas down to near zero.

Industry experts say it may be too late to try to curb PFC emissions from existing U.S. smelters. 

Aging U.S. smelters are like Model T cars, said Barry Welch, a chemical engineering professor at the University of New South Wales in Sydney, who has consulted for many of the world’s leading aluminum production companies. 

“They are out of date,” Welch said of the current fleet of U.S. smelters, which were built from 1902 to 1980. “They should be shut down.”

Yet security experts say the U.S. must find a way to keep the aluminum plants open. The strong, lightweight metal is used to make more fuel-efficient cars and airplanes as well as solar panels and satellites.  

“Just as we are reliant on the Middle East for oil, we will soon be in position where we will be reliant on China and Russia for aluminum,” said Joe Quinn, the vice president of strategic industrial materials at SAFE Commanding Heights, based in Washington, D.C., which advocates for U.S. energy security. “There is a legitimate need to stabilize the aluminum sector for national security reasons.”

In written testimony submitted to the U.S. International Trade Commission in 2017, Century Aluminum executives said aluminum producers were being “decimated” by “unfair practices of Chinese aluminum producers.”

“American smelters from New York, to Indiana, to Washington have already closed their doors, depriving local workers and communities of sorely needed jobs and tax revenue,” company officials wrote. “The continued viability of the aluminum industry outside of China, and especially in the United States, is dependent upon a prompt and effective solution to China’s overcapacity and overproduction.”

In 2018, President Donald Trump levied tariffs on imported aluminum. The tariffs remain largely in place. However, in June, Century announced it was temporarily shutting down production at its largest U.S. plant, an aluminum smelter in nearby Hawesville, Kentucky.

A plant employee walks through the parking lot at Century Aluminum Company's smelter
Century Aluminum Company's smelter in Hawesville, Ky. was temporarily shut down in June.Luke Sharrett / The Washington Post via Getty Images file

It was the only U.S. smelter to make high-purity “military grade” aluminum, used in fighter jets and in lightweight armor plating. Century said at the time that the closure would last “nine to twelve months” and that it was due to “soaring energy prices.” 

Few industries have contracted as quickly and as completely as U.S. aluminum smelting.  

“There were 23 operating in 2000 and five now,” Andy Thompson, the president of the local United Steelworkers of America union in Robards, said of the U.S.’s last remaining aluminum smelters.

Of the five remaining facilities, only the Century Aluminum Sebree plant in Robards, which employs 625 workers, and a smaller Alcoa plant in Massena, New York, run at full capacity.   

Brad Schneider, the judge executive, or head of the county government, for Henderson County, which includes Robards, said that if the Century plant ever closed, it would be a significant loss for the region.  

“Generations of people have worked there, the same families,” Schneider said. “It would be a definite blow.

“We’re all saddened by what happened to Hawesville,” he said. “If we don’t solve or at least protect our heavy industry and their energy needs, we’ll regret it. On multiple levels.”

Judge Executive Brad Schneider
Henderson County Judge Executive Brad Schneider. Phillip McKenna/NBC News

Steinsen, of Century Aluminum, said the company has no plans to shut down its Sebree facility in Robards. “Sebree has unique operational and commercial advantages that Hawesville does not, and we are confident that Sebree is well positioned to continue operating,” Steinsen wrote. 

A 76% drop in PFC emissions 

Aluminum smelters turn alumina ore into aluminum by feeding alumina powder into a bath of molten salt and running large amounts of electricity through the mix in a cell, or “pot.”   

If the concentration of the alumina dips too low, PFCs, an unwanted byproduct, can form quickly. 

EPA officials first became aware of the issue in the early ’90s, yet rather than propose regulations, they worked with aluminum manufacturers to see whether they could find a way to reduce PFC emissions without regulations.   

The result, the agency’s Voluntary Aluminum Industrial Partnership, which launched in 1995, was wildly successful. PFC emissions per ton of U.S. aluminum dropped by 76% from 1990 to 2015, according to the EPA. 

“In addition to the environmental benefits, participation improves operational efficiency and benefits a company’s bottom line,” a 2008 EPA report concluded. 

In 2015, when the U.S. aluminum production was in steep decline, the EPA ended its industry partnership. While the end of the program did not appear to have an impact on plant activities, the EPA did not respond to questions about why they do not regulate PFC emissions from aluminum plants or if they plan to in the future, and declined repeat requests to speak with an agency expert currently working on emissions policies. A spokesperson for the agency said, “EPA continues to track facility specific emissions from the aluminum industry through the Greenhouse Gas Reporting Program.”  

Today, PFCs are a small fraction of aluminum production’s total greenhouse gas emissions. The vast majority, about 70%, come indirectly from burning fossil fuels in power plants to run the energy-intensive smelters, according to a 2019 study published in the Journal of The Minerals, Metals & Materials Society

But the remaining PFC emissions are still significant. In 2019, 7,510 metric tons of PFCs were emitted from global aluminum production, according to a study published last year in the Journal of Geophysical Research — Atmospheres. That equals the annual emissions of 12.5 million automobiles, according to the EPA.  

Aging technology and the Inflation Reduction Act

In May 1998, Alcan Aluminum, the former owner of what is now Century Aluminum Sebree, completed a $1.6 million investment in new equipment for the facility. Alcan installed a “demand feed” system that optimized the rate at which alumina was fed into the aluminum pots. 

The investment cut the emissions intensity of CF4, the primary PFC emitted in aluminum production, in half, from 2 to 3 tons of carbon dioxide equivalent per ton of aluminum to just over 1 ton of carbon dioxide equivalent, according to a 1999 EPA report.  

The emissions reduction made Alcan a climate leader among aluminum producers in the late ’90s. Twenty-four years later, the emissions intensity of CF4 from the plant remains virtually unchanged, at just under 1 ton of carbon dioxide equivalent per ton of aluminum, making Century, the current owner, a climate laggard.

Steinsen said the company has focused on reducing the PFC emissions intensity from the Sebree facility this year. New controls were added, and “we anticipate that these changes will reduce the plant’s PFC intensity,” Steinsen said. 

The recently passed Inflation Reduction Act, the single biggest climate investment in U.S. history, made $5.8 billion in grants and other incentives available for heavy industry to adopt emissions-abating technologies. Aluminum manufacturers could use the money to install better control systems that reduce PFC emissions and increase production efficiency, said Quinn, of SAFE Commanding Heights, the U.S. energy security advocacy organization.   

The act also appropriated $500 million for “enhanced” use of the Defense Production Act. Quinn said the additional money could be used to subsidize the cost of electricity to produce aluminum, which the act designated as a “critical mineral.”   

The Inflation Reduction Act could breathe new life into the U.S. aluminum industry, said Mike Tanchuk, a veteran of the aluminum industry. With the backing of Blue Wolf Capital Partners, a private equity firm, and the AFL-CIO labor union federation, Tanchuk seeks to harness funds under the act as part of an effort to buy Alcoa’s Intalco smelter, upgrade its technology and power the facility with renewable energy to manufacture “green,” or low-carbon, aluminum.   

“Potential federal funding from the Inflation Reduction Act and the continued support from Governor Inslee and other leaders in Washington state have revived my hope that Intalco can be saved,” said Tanchuk, the head of the recently formed company Green Aluminum — Intalco Works. (Jay Inslee is the governor of Washington.) 

Beck, of Alcoa, said the company has participated in discussions with a prospective buyer, “although the various conditions for a successful sales transaction have not been met to date.”  

Tanchuk previously worked as an executive for Alcoa, where he oversaw a prior reopening of the Intalco smelter in 2002, and at Century Aluminum, where he oversaw an expansion of the Nordural smelter in Iceland in 2006. He said technology upgrades at the Intalco plant would result in significantly reduced PFC emissions similar to those of the Nordural plant. 

“The planned modernization of Intalco will result in a significant reduction of emissions, including greenhouse gases,” he said. “We still face some hurdles caused by recent geopolitical turmoil, such as high energy prices, but these events only reinforce my strong belief that now more than ever we need a reliable supply of domestic aluminum.”