Environmental groups are criticizing Nippon Steel’s recent investments in its Pittsburgh-area U.S. Steel mills for continuing the company’s reliance on coal to produce steel. As a result, they say, the region’s air quality is unlikely to improve.
Nippon Steel recently announced it would replace a nearly 90-year-old hot strip mill at U.S. Steel’s Irvin Works in West Mifflin with a brand new hot strip mill at Edgar Thomson Works in nearby Braddock. The company says it’s targeting 2029 for the startup.
The new mill will take steel slabs it currently produces at Edgar Thomson Works and make flat-rolled products, like the kind used by the auto industry.
Nippon said the project, part of a $2.5 billion investment in the Mon Valley, would produce more steel with fewer emissions, including particulate matter, which is linked to heart and lung diseases.
“The hot strip mill will incorporate the best technology available, and that means we will be using the best methods to keep emissions down,” said Andrew Fulton, a U.S. Steel spokesman, in an email response to questions sent to the company. “The new hot strip mill will result in a decrease in emissions per ton of steel produced, as compared to our existing hot strip mill.”
In an installation permit application submitted to air quality regulators at the Allegheny County Health Department, U.S. Steel reported that emissions associated with its strip mill operations would decrease from 25.4 tons per year as emitted from the Irvin plant to a potential 22 tons per year at the new operations. Hot strip mills heat steel slabs to very high temperatures and roll them into coils for a variety of applications.
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The new mill would still rely on coke, a refined form of coal, produced at the company’s nearby Clairton coke works.
At a press conference earlier this week with groups from Pennsylvania and Indiana, home to U.S. Steel’s Gary Works, Matthew Mehalik with the Breathe Project, based in Pittsburgh, criticized the company for investing in technologies that continue to rely on coke.
“None of it does anything to address the consumption of coke and the production of coke at Clairton,” Mehalik said. “It’s profiting at the expense of lives and health of people in these communities.”
The coke works has violated the Clean Air Act in each of the past 12 quarters, according to the EPA, and is by far the largest single source of air pollutants in Allegheny County, according to the county health department. The two highest levels of particulate matter recorded by the state were at air monitors located near the Clairton and Edgar Thomson plants. Both monitors failed to meet revised federal clean air standards.
In addition to local air pollution, the Mon Valley Works is a major contributor of greenhouse gas pollution. The addition of a hot strip mill at Edgar Thomson Works could increase carbon emissions there by 750,000 tons per year, the equivalent of adding 150,000 cars on the road, according to EPA estimates.
According to Fulton, the increase is due to the fact that the emissions estimates provided to regulators are based on “maximum potential emissions under worst‑case operating assumptions.”
“Because permits must account for a theoretical worst-case scenario to ensure the best pollution control equipment is installed as part of the project, they reflect what the facility could emit if it operated at the highest possible capacity at all times—not what it is expected to emit on a day-to-day basis,” Fulton wrote in his email response. “The permit application submitted by U. S. Steel…includes best available control technologies and work practices to mitigate emissions. The new hot strip mill will be more efficient than the current one at Irvin, so the emissions per ton will be reduced.”
Roger Smith of the industry watchdog Steelwatch said the upgrades at Edgar Thomson Works don’t incorporate newer, low-carbon technologies that could help clean up the steel industry, which accounts for up to 10 percent of all greenhouse gas emissions.
“These aren’t the fundamental transformational changes that are going to keep the industry relevant for future generations. These are stopgap things to make U.S. Steel profitable in the short term,” Smith said.
Those technologies include direct reduction of iron, a gas-based process that replaces coke in the ironmaking process with hydrogen or natural gas. From there, the iron is turned into steel in an electric arc furnace. In April, U.S. Steel announced it is building a $1.9 billion direct reduction facility at its Big River Steel Works in Osceola, Arkansas, to feed its electric arc furnaces there.
The company said switching to electric arc furnaces in the Mon Valley would result in years of disruptions and job losses, and that the blast furnace technology used at Edgar Thomson produces high-grade “primary” steel superior to steel from plants that use low-carbon technologies.
“[C]ertain advanced steel products—particularly those used in automotive, energy, and packaging applications—cannot yet be produced at scale using electric arc furnace (EAF) technology,” said Fulton.
Nippon purchased U.S. Steel last year, after gaining approval from the Trump administration.
