Worldstainless spells out recycling-decarbonization connection

The Brussels-based World Stainless Association (Worldstainless) has released a report outlining carbon emissions data tied to the stainless steel industry, including a section that spells out how using recycled metal in higher percentages lowers mill emissions levels.

The September report outlines the average emissions differences between scrap-based melt shop production and nickel pig iron (NPI) production systems.

The report’s analysis, using what it calls a “cradle-to-gate” model measuring Scopes 1, 2 and 3 emissions, finds a stainless mill using 85 percent scrap feedstock will average 1.95 tons of CO₂ emissions per ton of metal produced.

That compares with the following emissions levels as the percentage of scrap decreases: 75 percent scrap content yields 2.45 tons of emissions per ton made; 50 percent scrap content leads to 3.7 tons of CO₂ per ton produced; and a mill using just 30 percent scrap will churn out 6.8 tons of CO₂ per ton of stainless steel it produces, according to Worldstainless.

While that makes recycling a clear path forward in lowering the sector’s carbon footprint, the organization says a ceiling remains in terms of global scrap consumption.

“Although 95 percent of stainless steel scrap is collected for recycling at the end of life, there is not enough stainless steel scrap available globally, therefore these production routes will co-exist for the foreseeable future,” Worldstainless says.

The report’s authors also say that over the coming years, the production emissions associated with NPI will fall progressively as greener technologies in the production of NPI become more widely used.

“Like any other major industry, the stainless steels industry consistently endeavors to reduce its operational CO₂ emissions year-on-year," Worldstainless says. "Industry direct emissions and indirect emissions have, due to solid industry improvement efforts, progressively reduced over the last decade.”

The organization also says life cycle analyses can work in favor of stainless steel as a material with a potentially reduced carbon footprint.

“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,” according to Worldstainless.

The organization uses a portrayal of the life cycle of two reusable water bottles—one made with stainless steel and the other with polyethylene terephthalate (PET) plastic—to illustrate its point.

“At first sight, the stainless steel water bottle has higher CO₂ production emissions, but because this bottle will last 20 years or more and a PET bottle will need to be replaced at least 10 times in these 20 years, the stainless steel water bottle will be the lowest emitter of CO₂,” Worldstainless says.

The full 15-page stainless sector emissions report can be downloaded from the World Stainless Association website.