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Why American Aluminum Plants Emit Far More Climate Pollution Than Some of Their Counterparts Abroad

Short answer: They’re old.

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This article was published in partnership with NBC News

ROBARDS, Ky.—As Mary and Ed Cupp drove down a country lane toward the front gate of Century Aluminum Sebree, they couldn’t help but wonder about the barrage of signs extolling the company’s core values of “health, safety, and sustainability.”

One billboard in particular, a sign informing passersby that “we each have the capability—and the responsibility—to lead,” caught their eye.  

“If you live a good life, and you live your principles, people see it; they don’t need to be told,” Mary Cupp, 78, a member of the local Sierra Club group said, recounting a lesson she learned early in life growing up a pastor’s daughter in nearby Owensboro, Kentucky. 

Cupp, a retired professor, had reason to be skeptical. Century Aluminum Sebree, a series of long, metal buildings built along the Green River nearly half a century ago, is the largest emitter of perfluorocarbons (PFCs) from aluminum production in the United States.


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Though considered non-toxic by the U.S. Occupational Safety and Health Administration,  tetrafluoromethane (CF4) and hexafluoroethane (C2F6), PFCs that are unwanted byproducts of aluminum production, are among the most potent and longest-lasting greenhouse gases on the planet. They 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,” the Environmental Protection Agency notes.

PFCs threaten “the public health and welfare of current and future generations,” according to a 2009 determination by the EPA as part of a sweeping “endangerment finding” on greenhouse gases. However, unlike carbon dioxide and methane, the EPA does not regulate PFCs.

Why They're Called the Immortals

CF4, the primary PFC released by Century Aluminum, is 7,380 times worse for climate change than carbon dioxide on a ton-for-ton basis over a 100-year period. But, unlike CO2, which remains in the atmosphere for approximately 300-1,000 years, CF4 remains in the atmosphere for 50,000 years.  

In 2021, the Sebree plant, the largest U.S. aluminum production facility operating at full capacity, vented 24 tons of perfluorocarbons (PFCs) into the air. The emissions equal the annual greenhouse gas emissions of 40,000 automobiles—ones that will remain on the theoretical 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 perfluorocarbons (PFC) emissions per ton of aluminum, as compared to the company’s Sebree plant, according to an Inside Climate News assessment of Environmental Protection Agency data as well as financial and environmental reports published by Century and Nordural, its Icelandic subsidiary.

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 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.  

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 curtailing production. 

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.”

Related: Want to Help Reduce PFC Emissions? Recycle Those Cans

Century Aluminum offered a similar explanation for its Sebree plant, which was completed in 1973. 

“When comparing numbers between Sebree and Norðurál Grundartangi it is important to note that the Iceland facility is a (sic) newer and more technologically advanced,” Steinunn Dögg Steinsen, vice president of health safety and environment for Century Aluminum, said in a written statement. 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.  

Century Aluminum Sebree in Robards, Kentucky is one of only five remaining active aluminum smelters in the U.S. Built in 1973, Century Aluminum Sebree is the largest U.S. aluminum production facility, or smelter, operating at full capacity and the largest emitter of perfluorocarbons (PFCs) from aluminum production in the United States. Credit: Phil McKenna
Century Aluminum Sebree in Robards, Kentucky is one of only five remaining active aluminum smelters in the U.S. Built in 1973, Century Aluminum Sebree is the largest U.S. aluminum production facility, or smelter, operating at full capacity and the largest emitter of perfluorocarbons (PFCs) from aluminum production in the United States. Credit: Phil McKenna

From Leader to Laggard

Twenty years ago, the U.S. led the world in aluminum production and in a worldwide effort to reduce PFCs. Now, just 1.5 percent of global aluminum smelting, or production, takes place in the U.S. Meanwhile, efforts to reduce PFC emissions in America have stalled while the cleanest smelters in other countries have brought emissions of the potent greenhouse gas down to near zero.

In some cases, multinational companies have slashed emissions at their overseas facilities while continuing to operate older U.S. plants with some of the highest PFC emissions rates in the world.

Industry analysts say the stark contrast is due to regulatory differences and the relative cost of electricity, the largest expense for the energy-intensive industry. Iceland, which is subject to the European Union’s carbon trading market, places a high price on PFC emissions based on the gas’s outsized climate impact. There is no such fee or regulatory limit for PFC emissions in the U.S. 

Low-cost hydropower in Iceland also makes investments in new equipment worthwhile there, while the high cost of electricity in the U.S. makes the cost of new equipment that could boost production and limit emissions hard to justify, industry experts say.

When compared to facilities with the lowest PFC emissions worldwide, emissions from Sebree are more than 40 times higher per ton of aluminum produced, according to a study published earlier this year in the journal Light Metals.

Environmental advocates say the declining U.S. industry needs revitalization.  

“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,” Nadia Steinzor, a policy and research consultant with the Environmental Integrity Project based in Washington, D.C., said. “If there are technological fixes that the industry can employ to lower or eliminate climate emissions, they should be required to adopt them.”

Once Climate Leaders, Now Laggards

Industry experts say it may already be too late for existing U.S. smelters.

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

“They are out of date,” Welch said of the current fleet of U.S. smelters, which were built between 1902 and 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 everything from more fuel-efficient cars and airplanes to 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, vice president of strategic industrial materials at SAFE Commanding Heights, an organization based in Washington, D.C., that advocates for U.S. energy security. “There is a legitimate need to stabilize the aluminum sector for national security reasons.”

A 76 Percent Drop in PFC Emissions 

Prior to the 1990s, plant operators didn’t pay much attention to the occasional chemical imbalance in their aluminum pots, causing PFCs to form, said Alton Tabereaux, who worked as a research and technology development manager from the 1970s to the early 2000s for Reynolds Aluminum and Alcoa Primary Metals. In fact, the industry believed the occasional imbalance was a necessary part of aluminum production because it helped eliminate any excess alumina sludge that may have built up, Tabereaux said.  

In 1993, a study published in the journal Science noted that CF4, a potent greenhouse gas and byproduct of aluminum production, remains in the atmosphere for tens of thousands of years. When Cindy Jacobs, then a manager in the EPA’s Global Change division, became aware of the issue that same year, she knew something had to be done.

“We realized it’s something we really should be looking at,” Jacobs, now the chief of the agency’s ENERGY STAR Commercial and Industrial Branch, recalled of the time.

Aluminum's Super Pollutants

Yet, rather than propose regulations, Jacobs and her colleagues reached out to aluminum manufacturers to see if they could find a way to reduce PFC emissions without regulations.   

“We wanted to see what we could do in a partnership framework to help reduce those emissions,” said Jacobs, who in 1995 became the first program manager of the EPA’s Voluntary Aluminum Industrial Partnership. 

When the EPA partnered with industry they found that the chemical imbalance, known as an “anode effect,” released large volumes of PFCs and also reduced aluminum production efficiency.

“The companies realized that if we can reduce the anode effects then we can be more efficient and increase production,” Tabereaux said.

Sally Rand, a former EPA official who oversaw many of the agency’s industry partnerships in the 1990s and early 2000s, said the work also underscored the damage aluminum production was causing.

“Not only are they not producing efficiently, they’re emitting these chemicals that are altering the path of the world,” Rand said.

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The end result was wildly successful: PFC emissions per ton of U.S. aluminum dropped by 76 percent 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, at a time when the U.S. aluminum production was in steep decline, the EPA ended its industry partnership. 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 represent a small fraction of aluminum production’s total greenhouse gas emissions. The vast majority, approximately 70 percent, come from burning fossil fuels in power plants to run the energy-intensive smelters.

But, the remaining PFC emissions are still significant. In 2019, 7,510 metric tons 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.  

Pollutant ‘Whack-a-Mole’ 

When Mary Cupp returned to Owensboro with her husband Ed in 2006, she quickly noticed two things: Her childhood home was now surrounded by coal plants and aluminum smelters, and when she spent time outside, her eyes burned.

“I never had any problems with environmental pollution, and I’ve never had allergies in my life until I moved back here,” said Mary, who retired in 2006 from Auburn University, where she specialized in biochemistry and immunology research.

The Century Aluminum Sebree plant in Robards is 30 miles to the southwest of their home in Owensboro. Just to the northwest on the opposite side of the Ohio River in Warrick, Indiana, Alcoa runs a smelter powered by the company’s own coal fired power plant. Twenty five miles to the northeast is a third smelter, owned by Century Aluminum, though the company temporarily closed the plant earlier this year.

Soon after returning to Owensboro, Mary, who would go on to chair the local Sierra Club group, Ed, and other members of the organization tried to shut down a local coal fired power plant owned by their local utility company, the Owensboro Municipal Utilities (OMU).

Mary and Ed Cupp of Owensboro, Kentucky, succeeded in getting their local utility company, Owensboro Municipal Utilities, to shut their coal fired power plant. Owensboro is surrounded by aluminum smelters. Neither Mary or Ed were aware of their perfluorocarbon emissions. Credit: Phil McKenna
Mary and Ed Cupp of Owensboro, Kentucky, succeeded in getting their local utility company, Owensboro Municipal Utilities, to shut their coal fired power plant. Owensboro is surrounded by aluminum smelters. Neither Mary or Ed were aware of their perfluorocarbon emissions. Credit: Phil McKenna

In 2018, OMU not only agreed to shut down its aging coal plant, but also announced plans to purchase power from a large solar power installation to supply some of the city’s power needs. The utility ultimately decided against the solar project and instead purchased their power from a nearby electric company powered almost entirely by coal.

“It was very disheartening,” Mary recalled from the front passenger seat of the couple’s all-electric Nissan Leaf. “The goal was to try to move beyond coal. And we were just going laterally to a different coal fired plant.”

When asked about PFC emissions, neither Mary nor Ed were initially aware of the pollutant and its release from the Robards plant and the other nearby smelters.

“It’s almost like whack-a-mole,” said Ed, 81, a retired medical entomologist who also taught at Auburn University. “You get rid of one thing and another thing pops up. It just makes you wonder where it will end.”

American Aluminum vs. Chinese Aluminum 

In 2000, there were 23 primary aluminum smelters operating in the U.S.; today, there are five, said Andy Thompson, president of the local United Steelworkers of America union in Robards.

Of the remaining facilities, only the Century Aluminum Sebree plant, 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 county government, for Henderson County, which includes Robards, said 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.”

Brad Schneider was recently re-elected the judge executive, or head of county government, for Henderson County, which includes Robards. If the Century plant ever closed, it would be a significant loss for the region, Schneider said. Credit: Phil McKenna
Brad Schneider was recently re-elected the judge executive, or head of county government, for Henderson County, which includes Robards. If the Century plant ever closed, it would be a significant loss for the region, Schneider said. Credit: Phil McKenna

In written testimony submitted to the United States International Trade Commission in 2017, company officials 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 Trump levied tariffs on imported aluminum. The tariffs remain largely in place. However, in June, Century announced it was curtailing production at its then-largest U.S. plant in operation, an aluminum smelter in nearby Hawesville, Kentucky.

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 was due to “soaring energy prices.”

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,” she said. 

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

Aging Technology and the Inflation Reduction Act

In May 1998, Alcan Aluminum, the former owner of what is now the Century Aluminum Sebree smelter, completed a $1.6 million investment in new equipment for the facility that cut the emissions intensity of CF4, the primary PFC emitted in aluminum production, in half, according to a 1999 EPA report.  

The emission 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, making Century, the current owner, a climate laggard.

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 these additional funds could be used to subsidize the cost of electricity for the  production of aluminum, which the act designated as a “critical mineral.”  

Steinsen said the company has focused on reducing the PFC emissions intensity from the Sebree facility in 2022. One challenge was simply space: Sebree’s relatively low ceilings made it difficult to add new control technology to reduce PFC emissions, she said. 

Nonetheless, new controls were added and “we anticipate that these changes will reduce the plant’s PFC intensity,” she said.  

Mike Tanchuk, a veteran of the aluminum industry, said the IRA could breathe new life into the U.S. 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 IRA funds as part of an effort to purchase 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,” Tanchuk, head of the recently formed company Green Aluminum–Intalco Works, said. 

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 company’s Nordural smelter in Iceland in 2006. He said technology upgrades at the Intalco plant would result in PFC emissions comparable with those of the Nordural plant. 

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.” 

“The planned modernization of Intalco will result in a significant reduction of emissions including greenhouse gases,” Tanchuk 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.”  

Moving Toward ‘Low Carbon’ Aluminum

The International Aluminium Institute, a global aluminum industry trade group based in London, has pledged to reduce greenhouse gas emissions from the aluminum sector by 80 percent by 2050 at the same time as demand for aluminum is anticipated to grow by over 70 percent.

Meanwhile, leading buyers of aluminum including Ford Motor Company and Apple are setting targets for “low carbon” aluminum by 2030.

“Come with us,” said Sue Slaughter, supply chain sustainability purchasing director for Ford, the largest buyer of aluminum in North America, recounting what she tells producers about the need to reduce aluminum’s carbon footprint. “We’ll take you on the journey with us. We want to support you in that journey. But if you aren’t prepared to do that, then we will have to look at alternatives.”

One way U.S. smelters could reduce emissions is by powering their plants with renewables. Of the five remaining U.S. smelters, one, an Alcoa plant in Massena, New York, is powered by hydropower. Three, including Century Aluminum Sebree, get their power from a mix of mostly coal and methane gas, supplied by the regional electricity grid. Alcoa’s smelter in Warrick, Indiana, is powered entirely by coal.

Wind and solar power purchase agreements, where companies buy electricity directly from a renewable energy developer, are common in other industries like information technology companies that require large amounts of electricity to power their data centers.

“The work we need to do is figure out why this is going so slowly,” said Annie Sartor, aluminum campaign director with the recently launched climate advocacy group, Industrious Labs, on the lack of renewable energy power purchase agreements in the aluminum sector despite their proliferation at leading technology companies like Google. “Why is it not easy to do what Google has done?”

Beck of Alcoa said 81 percent of his company’s global smelting portfolio is powered by renewable energy and the company “continues to evaluate options for the future to increase its percentage of renewable energy.”

Alcoa is also part of a joint venture to develop “inert anodes” for aluminum smelting that Beck said are a “potential game changer.” Today’s aluminum smelters use positive electrodes, or anodes, made of carbon, which slowly break down and contribute to the formation of carbon dioxide and perfluorocarbon emissions during aluminum production.

Inert anodes, long considered the “holy grail” of aluminum production, would eliminate PFC and carbon dioxide emissions from aluminum production and would instead release only oxygen, Beck said.

ELYSIS, a joint venture between aluminum producers Alcoa and Rio Tinto, produced its first small batch of aluminum using inert anode technology for Apple in 2019. The company aims to have the technology commercially available in 2024, Beck said.

Others are not convinced.

Welch, who worked on efforts to develop inert anode technology for more than a decade, said it is unlikely to become a dominant commercially viable option for aluminum extraction. 

“It will never happen,” said Welch. “There has been probably $2 billion at least spent on inert anode research in all the top labs in the world and they still have the same problem as they had after the first year.”

If the technology becomes commercially available, it remains unclear if Alcoa would make the necessary investments for its use in the U.S.

‘Do What Is Right’

As the Cupps neared the front gate of Century Aluminum’s smelter, Ed, seeking to avoid a run-in with the facility’s security guards, prepared to turn their car around.

It was a late September morning, yet, outside the couple’s climate-controlled car, the temperature soared, already well on its way to a record-setting 95 degrees.

A billboard at the entrance to Century Aluminum Sebree in Robards, Kentucky admonishing workers to "Do what is right, not what is easy." Credit: Phil McKenna
A billboard at the entrance to Century Aluminum Sebree in Robards, Kentucky admonishing workers to “Do what is right, not what is easy.” Credit: Phil McKenna

“I remember September as being cool,” Mary mused of her childhood. “You wore sweaters to school.”

Before making a U-turn, Ed read out loud one last company billboard, a sign that admonished passersby to “do what is right, not what is easy.”

“All right,” Ed said, turning to Mary. “Hold them to it.”

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