Replacing corroded metal is a major environmental concern – Zoo House News
Each year, the United States spends nearly $1 trillion to combat metal corrosion, an electrochemical reaction that occurs when metals oxidize and begin to rust. By tackling this surprisingly insidious problem, researchers have now estimated how much corrosion is gradually worsening global carbon emissions.
Global steel production has been steadily increasing for decades – and because steel has poor corrosion resistance, part of that demand is to replace steel used in building materials that have corroded over time, from bridges to automobiles. Reducing the amount of steel that needs to be replaced due to corrosion could have a measurable impact on how much greenhouse gases are produced during steelmaking, said Gerald Frankel, co-author of the study and professor of materials science and engineering at Ohio State University,
Although previous studies have estimated the current economic cost of corrosion at approximately 3-4% of a nation’s gross domestic product, this new study, led by Ohio State graduate student Mariano Iannuzzi, is the first to quantify the environmental impacts associated with steel corrosion.
The study was recently published in the journal npj Materials Degradation.
“Given society’s reliance on coal fuel, iron and steel production is one of the largest greenhouse gas emitters of any industry,” Frankel said. “But most of the costs associated with the industry actually come from the energy that goes into making steel, and that energy is lost when the steel turns back to rust, which resembles its original form of iron ore.”
How long it takes for steel to corrode depends largely on environmental exposure and alloy composition, but this environmentally damaging problem is only getting worse, Frankel said.
Using historical carbon dioxide intensity data to estimate carbon dioxide levels per year starting in 1960, the researchers found that steel production accounted for 27% of the global manufacturing sector’s CO2 emissions in 2021 and about 10.5% of total global CO2 emissions worldwide. Corroded steel substitutes accounted for about 1.6 to 3.4% of the emissions.
But there is some good news, the study found. Due to steel industry regulations, technological advances in the steelmaking process have resulted in a 61% reduction in energy consumption over the past 50 years.
Despite this improvement, the study’s findings are a call for policymakers and industry representatives to change and coordinate international policies related to steel production and corrosion management, Frankel said.
“Coordinated international strategies, as well as reducing global steel demand through the use of corrosion mitigation best practices, could better improve global corrosion management strategies and drastically reduce the increase in greenhouse gas emissions we are seeing due to repeated replacement of corroded steel,” he said.
Unless action is taken soon to improve steel’s carbon footprint, the study finds that greenhouse gas emissions from the steel industry could reach about 27.5% of the world’s total CO2 emissions by 2030, with corroded steel accounting for about 4 to 9% of which accounts for number. Such an outcome would render the Paris Agreement’s goals of limiting global warming to 1.5 degrees Celsius, as well as the US’s own domestic climate goals, all but impossible. The study finds that management strategies such as leveraging machine learning technologies could be one of the best opportunities we have to reduce the Earth’s carbon dioxide levels.
However, if humans cannot meet these conditions, the consequences for the Earth’s climate will be devastating. Therefore, more people need to be made aware that a low-carbon steel industry is needed to prevent such a dystopia, Frankel said.
“Global warming is a societal challenge that requires the coordination of many multidisciplinary approaches,” said Frankel. “Our work brings to light a problem that seems to have gone under the radar in terms of the importance of amplifying the problem.”