What is the environmental impact of steel corrosion?

We are used to talking about the environmental impact of steel production. The most prominent global steel players have long since begun their race to reduce CO2 emissions by adopting new technologies, such as carbon capture and storage (CCS), utilizing waste gases for energy generation, and implementing low-carbon alternatives like hydrogen, to reduce their footprint.

However, one aspect that has not been the subject of much analysis so far has been the role of corrosion.

Steel corrosion is the degradation of the material properties and performance caused by chemical or electrochemical reactions with the environment. The most common form of steel corrosion is rust, which occurs when steel is exposed to water and oxygen. Since corroded products need to be repaired or replaced to preserve the performance and safety of structures, one can easily understand the role of corrosion in increasing the need for new steel production. Indirectly, steel corrosion can contribute to rising emissions associated with making steel.

A new study, led by Ohio State University alum Mariano Iannuzzi, is the first to quantify the environmental impact associated with steel corrosion. The article was published last December in the journal npj Materials Degradation. According to Gerald Frankel, co-author, and professor in materials science and engineering, ‘reducing the amount of steel that needs to be replaced due to corrosion could have measurable effects on how much greenhouse gases are produced to make steel.’

The study found that in 2021 while global steel production accounted for about 10.5 percent of total carbon emissions, replacing corroded steel represented between 1.6 and 3.4 percent of emissions.
Stricter regulations and technological advances have reduced energy consumption in the steelmaking process by 61% over the past 50 years, but more needs to be done to lower the industry's carbon footprint. The study warns that without further improvements, emissions from the steel industry could reach 27.5% of the worldwide carbon emissions by 2030, with corroded steel representing about 4 to 9% of that number. That would make climate goals set by the Paris Agreement unfeasible. 

Preventing or reducing steel corrosion may be achieved, for instance, by using protective coatings or cathodic protection methods, through proper maintenance and control plans, implementing corrosion inhibitors, or simply choosing corrosion-resistant alloys. Adopting these measures can help mitigate the negative impacts of steel corrosion and thus reduce overall emissions associated with steel production.