A 14-page report published by the Brussels-based WorldStainless organization examines the differences between scrap-based and nickel pig iron (NPI)-based production systems to make stainless steel, finding that using more scrap translates to lower CO2 emissions.
The report and the findings tie into what developed as the main topic at a stainless steel-focused session at recycling industry conference held last month.
“Like any other major industry, the stainless steel industry consistently endeavors to reduce its operational CO2 emissions year on year,” writes WorldStainless in a website posting announcing the availability of its report.
The organization says its report finds in part that although 95 percent of stainless steel scrap is collected for recycling at the end of its life cycle, “There is not enough stainless steel scrap available globally, therefore the [scrap based and NPI-based] production routes will co-exist for several decades to come.”
The report’s authors found that using 85 percent stainless scrap to feed a melt shop resulted in average emissions of 2.08 tons of CO2 for one ton of stainless steel produced. That contrasts with 6.82 tons of CO2 emissions per one ton of stainless steel produced when scrap contributes just 35 percent of feedstock.
The calculations include Scope 1, Scope 2 and Scope 3 emissions, which WorldStainless describes as “cradle to gate” emissions.
Scrap makes the biggest difference in Scope 3 emissions, which the United States Environmental Protection Agency describes as “the result of activities from assets not owned or controlled by the reporting organization, but that the organization indirectly affects in its value chain.” Collecting and transporting stainless steel scrap produces far fewer emissions compared with the mining and multiple stages of processing inherent with using NPI.
The WorldStainless report also makes a case for a longer life cycle for durable stainless steel products as working in the metal’s favor on the CO2 emissions front. “It should also be noted that the life cycle emissions associated with using stainless steels offer a different and more compelling perspective of the benefits of using sustainable and resilient materials,” writes the group.Concludes the organization, “For significant products and installations, around 70 percent of the life cycle emissions occur in the usage or operational phase, and therefore selecting materials that do not degrade and equally do not require significant maintenance and/or partial replacement presents a different and much lower emissions profile when compared to other material choices.”