Researchers Quantify Carbon Footprint of Steel Corrosion

Many studies have attempted to calculate the cost of corrosion, usually found to be 3% to 4% of the world’s gross domestic product (GDP).

That cost primarily comes in the form of materials replacement. But what is the environmental cost of that materials replacement?

Two Ohio State University (Columbus, Ohio, USA) researchers set out to determine the CO₂ (carbon dioxide) emissions associated with the steelmaking required to replace corroded steel. In their study, “The Carbon Footprint of Steel Corrosion,” they found that the CO₂ emissions required to replace corroded steel will be 4.1% to 9.1% of total CO₂ emissions by 2030. They took into consideration European Union and U.S. greenhouse gas reduction targets in making their conclusion.

“The perspective is about how we need to really recast corrosion as sustainability,” says Gerald Frankel, Ph.D., a study co-author. “Certainly, if something is corroding then it’s not sustainable. The world of sustainability doesn’t really think that way. They think more in terms of CO₂ and energy usage. So, the idea was to write a perspective that says this is how we need to be selling our field.”

Frankel is distinguished professor of engineering, professor of materials science and engineering, and director of the Fontana Corrosion Center at The Ohio State University. Ohio State alum Mariano Iannuzzi, who is now head of materials for Alcoa in Perth, Australia, led the study.

Cost of Corrosion to the Environment

“By recasting the cost of corrosion in terms of the cost of corrosion to the environment, we see that this is indirectly impacting the environment through the replacement of corroded steel,” Frankel says.

Studies suggest indirect costs of corrosion to be equal to direct ones, leading to a total cost of corrosion that could be over 6.2% of the global GDP, or about $6 trillion.

“All studies to date have focused on the monetary aspects of the problem, stressing financial losses as a way to persuade stakeholders to take proactive measures to mitigate corrosion,” they wrote in the study, initially published in December 2022 in npj Materials Degradation, an open-access journal from Nature Research.

The researchers found that the carbon footprint of corrosion is dominated by the CO₂ emissions produced by the steel production process.

They attribute a steep increase in steel production from the mid-1990s to economic growth in China and India, although it has increased steadily post-World War II.

To calculate the carbon footprint of steel corrosion, Iannuzzi and Frankel first sought to establish how much annual production of crude steel is required to replace corroded goods and infrastructure. They cited research that estimated that between 25% and 33% of annual steel production is destroyed by corrosion once in service.

“Given its high energy intensity, reliance on coal as primary fuel, and the use of CO as a reducing agent, iron and steel production is one of the largest CO₂ emitters of any industry,” the authors wrote in the study. “Indeed, steel production accounts for 27% of the CO₂ emissions of the global manufacturing sector, or about 10% of the total global CO₂ emissions in 2021.”

Technological advances in steelmaking processes driven by regulation due to environmental concerns have resulted in the reduction of energy consumption by 61% over the last 50 years, they write. In fact, they found that emissions produced in the early 2000s were equivalent to those between 1960 and 1980 despite much higher annual production.

In 2021, they reported, steel production represented about 10.5% of total global CO₂ emissions, with corroded steel replacement accounting for 1.6% to 3.4%.

The Paris Agreement

Frankel and Iannuzzi also explored the impact of the Paris Agreement on the steelmaking process.

The Paris Agreement is a legally binding international treaty on climate change adopted by 196 parties at the United Nations Climate Change Conference in Paris, France, in December 2015.

The study cited the European Union’s nationally determined contribution under the agreement, which is to cut greenhouse gas emissions by at least 55% compared to 1990 levels by 2030.

“The solution is in improvements to the steelmaking processes,” Frankel says. “There have already been lots of improvements in the release of CO₂ as a result of steelmaking. There are ways to do that that are not really being practiced at this point. But, on the other hand, it’s going to take a coordinated effort at government levels. It’s related to the cost of corrosion. By using best practices, you can reduce corrosion, which saves money, but then the point is here, it also saves the environment.”

Although the steelmaking process is not within AMPP’s purview, Frankel says, the association can have an impact through governmental lobbying efforts.

Iannuzzi and Frankel wrote in their study that the “no action” scenario is not a viable option, and they call for a drastic change in corrosion management policies.

“Failing to act would make meeting the Paris Accord and U.S. target reductions challenging,” they wrote, later adding, “implementing coordinated strategies requires the involvement of policymakers, industry, and academia through coordinated international action.”

They note that AMPP has proposed a systematic approach that combines expert know-how with economics to combat the cost of corrosion, adding, “this approach can address environmental considerations as well as financial aspects.”

They note that CO₂ emissions associated with corroded steel replacement represent a plausible minimum since they did not consider changes in the projected CO₂ emissions of the steel industry and ignored the degradation of materials other than steel, such as reinforced concrete, non-ferrous alloys, non-metallic materials, and organic coatings.

“The CO₂ emissions associated with, e.g., corrosion of reinforced concrete structures could increase the carbon footprint of corrosion substantially, since presently concrete production accounts for about 5% of the global CO₂ emissions,” they wrote. “In our analysis, we have also ignored the emissions of other greenhouse gases that contribute substantially to climate change, e.g., methane, which exacerbates the need for a swift implementation of corrosion control policies to reduce the carbon footprint of corrosion.”

Editor’s note: This article first appeared in the February 2024 print issue of Materials Performance (MP) Magazine. Reprinted with permission.