Crucial for a Clean Energy Economy, the Aluminum Industry’s Carbon Footprint Is Enormous

Aluminum is crucial for a clean energy economy, but its production is a leading source of greenhouse gas emissions as well as toxic air and water pollution, according to a new report by the Environmental Integrity Project on the “paradox” of aluminum.  

The report comes as the federal government is offering billions of dollars in grants to incentivize reductions in carbon emissions from heavy industry through the Inflation Reduction Act.

Aluminum is a key component in solar panels, wind turbines and electric vehicles due to its light weight, strength and durability. However, the production of aluminum also causes air and water pollution that harms communities and the environment and is a key reason why communities in Kentucky, Missouri and New York have sulfur dioxide (SO2) concentrations in the air that exceed federal limits, the report concludes. 

“Aluminum has a really big and positive role to play in the shift to clean energy and transportation and in creating a strong U.S. industry and jobs,” Nadia Steinzor, a policy and research analyst and lead author of the report, said. “But to make good on that promise, aluminum producers really need to reduce pollution and start modernizing and operating under updated rules so that there’s less harm to people, the environment and the climate.”

Global aluminum production accounted for the equivalent of 1.2 billion tons of carbon dioxide emissions in 2021, the same amount of emissions associated with the energy use of 150 million U.S. homes, according to the report.  

The report looked at all phases of U.S. primary aluminum production from a mine in Jamaica that provides bauxite, the key raw material in aluminum production, to a U.S. refinery that processes bauxite into alumina, to the smelters that transform alumina into aluminum. The report also analyzed emissions from a refinery of petcoke, an oil derivative used to make the carbon anodes that conduct electricity in aluminum smelters.

The report highlights problems posed by pollution from mercury, a toxic heavy metal that is an unwanted byproduct of alumina refining. The analysis also looked at releases of sulfur dioxide (SO2), which poses risks to respiratory and cardiovascular health and is a leading cause of acid rain, from aluminum production.

 Alcoa’s Warrick smelter in Newburgh, Ind., has particularly high discharges and emissions, the report said. From 2018 to 2023, the facility had 101 water pollution violations and 15 air pollution violations—far more than any other U.S. aluminum smelter—based on an Environmental Integrity Project review of compliance documents from state and federal agencies.  

A spokesman for Alcoa said the company is working to address the violations. 

“Alcoa is committed to operating in compliance with all applicable legal requirements, and we consistently work with regulatory authorities in a transparent manner where challenges exist,” he said.

The spokesman said the smelter has been in compliance with air permit limits since the second half of 2022 and the company continues to discuss water issues with the state’s environmental regulator to ensure compliance. 

Shayla Powell, an EPA spokeswoman, said the Indiana Department of Environmental Management has led enforcement activities at the Alcoa Warrick facility since 2018.

Alcoa “has an open agreed order with the Indiana Department of Environmental Management that covers water,” the company spokesman said. “As part of the order, the facility is implementing engineered solutions that will significantly reduce events that result in exceedances.” 

He added that some of the operations included in the permit for the Warrick facility are associated with an independent, non-Alcoa company that acquired a “rolling mill” from Alcoa in 2020.  

 The Warrick facility is also the only smelter, out of a total of six operating U.S. aluminum smelters, that relies entirely on coal power for its electricity needs. The Warrick smelter has its own dedicated coal-fired power plant.  

Aluminum smelting, or the conversion of alumina, which is extracted from bauxite, into aluminum, is an incredibly energy intensive process. Seventy-one percent of greenhouse gas emissions tied to the entire U.S. aluminum industry come from the production of electricity used to operate the smelter plants, according to the report. However, the energy mix that powers individual plants varies widely. An Alcoa smelter in Massena, New York, for example, runs on hydropower.

The Alcoa spokesman said the Warrick plant is an outlier in terms of its reliance on coal power. “Our global smelting portfolio is 86 percent powered by renewable energy resources,” he said. “Alcoa continues to evaluate our power supplies worldwide, including at the Warrick facility, as we work toward our net zero ambition by 2050.” 

Steinzor said the Warrick smelter’s many water pollution violations are likely due to mercury discharges from its adjoining power plant but added that the smelter, which was built in 1960, likely has elevated pollution due to a host of maintenance issues.

“There was probably something going on operationally at the plant, like failing equipment or inadequate maintenance, that would lead to excessive pollution,” Steinzor said. “These plants are just not being maintained and managed in the way that they should be because they continue to blow their limits.”

Climate pollution from the industry includes perfluorocarbons, man-made chemicals emitted during the smelting process that remain in the atmosphere, warming the planet, for 50,000 years. An investigation by Inside Climate News in 2022 found that Century Aluminum, a multinational aluminum manufacturer, emitted six times more perfluorocarbons per ton of aluminum at its Sebree, Kentucky, plant than at a newer plant that the company owns in Iceland.

One problem common to all U.S. smelters is a lack of pollution controls or “scrubbers” for sulfur dioxide, Steinzor said. Sulfur dioxide scrubbers are required for coal fired power plants and other industries, but “to date the aluminum industry has been given a pass,” she said.

New Source Performance Standards required under the Clean Air Act to keep pace with new pollution control methods have not been updated for primary aluminum in 25 years, according to the report. EPA has not revised the water pollution rules or “effluent limitation guidelines” for “nonferrous” metals, including alumina refining and aluminum smelting, since 1990, the report found.

Earlier this year the Environmental Integrity Project and several other organizations sued EPA for failing to update those  rules.

EPA did not immediately respond to a request for comment about air and water regulations for the aluminum industry.

Charles Johnson, president and chief executive officer of the Aluminum Association, an industry group, said his organization supports government efforts to decarbonize the electric grid, which will help aluminum producers and other manufacturers meet their emissions reduction targets.

“Building on decades of progress on decarbonization, aluminum companies are investing even more in new technologies including inert anode, green hydrogen and other platforms to further decarbonize the aluminum smelting process,” Johnson said of emerging technologies that could help reduce pollution from aluminum production.

“We also support aggressive efforts to grow aluminum recycling in the United States, including new recycling refund/container deposit laws and infrastructure investment.”

Another facility highlighted in the report for its high emissions is Atlantic Alumina’s refinery in Gramercy, Louisiana, which released 1,900 pounds of mercury into the air in 2021, according to the report.

“It’s a very toxic material and very toxic to the community,” said Wilma Subra, a chemist and environmental advocate based in Louisiana, who was quoted in the report. Subra said the red dust that billows from the facility and blankets the surrounding area is laced with the heavy metal. “It’s all over,” she said. “It’s on the roads and so when you drive your car, your car is flinging it up into the air.”

Atlantic Alumina did not respond to a request for comment.

The Inflation Reduction Act of 2022, the largest climate investment in U.S. history, included more than $6 billion in federal grants to help decarbonize heavy industry. Grant applications were due in August and recipients should be announced early next year.

“There is a real opportunity with the Inflation Reduction Act to invest in clean primary aluminum to meet growing needs, create jobs, reduce pollution and improve working conditions as we upgrade and modernize aluminum production,” said Annie Sartor, an aluminum expert with Industrious Labs, an environmental organization, who was not involved in the report. 

The Environmental Integrity Project “is right to highlight the current state of much of the aluminum industry,” Sartor said.  “However, there is no clean energy future without aluminum, so it’s what we do next that matters.”

“If the industry doesn’t clean up and modernize, they will be left behind,” Sartor added. “So we hope they can transform to meet the needs of the future.”