Stainless Steels and CO2: Industry Emissions and Related Data

Introduction

It should be noted that within the stainless steels industry there are essentially two production systems, namely;

1. The scrap-based production system in which the bulk of used raw materials are end-of-life stainless steels and/or similar alloy materials that are recycled to produce new stainless steels. This production system is aligned to geographical locations where the availability of end-of-life materials and scrap is high.
2. The Nickel Pig Iron (NPI) production system in which the bulk of the Nickel units required for stainless steel production is not derived from stainless steel scrap, but from extracted Nickel ores which are converted into NPI. This production system is aligned to geographical locations where the availability of stainless steel scrap is low.

There is currently insufficient available end-of-life stainless steel scrap in all regions of the world to permit only scrap-based production to exist. Therefore these production routes will co-exist for the foreseeable future.

General facts

Stainless steel is the term used to describe a remarkable and extremely versatile family of metals that contain a minimum of 10.5 % chromium. Chromium is essential to achieve the metal’s “stainless” properties. Other alloying elements (such as nickel, molybdenum and copper) provide a wide range of mechanical and physical properties.

For the stainless steel industry, scrap has a high intrinsic value. The only limitation is the availability of scrap, especially in emerging countries. The durability of stainless steel restricts the availability of scrap. For example, when stainless steel is used in buildings, it remains there for many years and cannot be reused before the building is dismantled. Stainless steel is 100 % recyclable and has one of the highest recycling rates of any material. It has been determined that at least 95 % of stainless steels are recycled at the end of their life.

Over the past 20 years the world has produced approximately 800 million metric tons of stainless steel (worldstainless, 2024). World annual production increased from 25 million tonnes to over 58 million tonnes over the same time period. The growth in the use of stainless steel has been the highest of any bulk formable material in the world (worldstainless, 2023). Stainless steel’s properties, such as its 100 % recyclability, reusability, durability, corrosion resistance, extremely low maintenance needs and product safety partly explain this amazing consumption growth.

CO2 Emissions

worldstainless has quantified the CO₂ emissions from the following three sources.

• Scope 1 Emissions which covers direct emissions from business-owned or business-controlled emission sources.
• Scope 2 Emissions which covers indirect emissions from the generation of purchased electricity, steam, heating and cooling consumed by the reporting company.
• Scope 3 Emissions which are associated with the extraction, preparation and transport of ores and the subsequent production and transport of ferro-alloys including the electricity needed for these processes.

These above-described three sources allow us to provide a cradle to gate view of the stainless steel industry’s CO₂ emissions.

CO2 production emissions for alloys in structures over 110 years of operational life

The figure shows the CO₂ production and maintenance emissions for stainless steels, carbon steel and aluminium. Two different types of produced stainless steel have been included, namely Stainless 1 which is produced with an 80% recycle content and Stainless 2 which is produced with a 60% recycled content.

The data comprises CO₂ tons emitted per ton of material produced (Scope 1 + Scope 2 + Scope 3) plus any CO₂ emissions associated with regular maintenance needs. The carbon steel emissions increase every 10 years due to regular maintenance needed to suppress corrosion. Stainless steel and Aluminium emissions do not increase as their passive films prevent the need for regular maintenance. The lifetime of stainless steels in-service beyond 110 years are not yet known as the industry is currently 111 years old.

Life Cycle Emissions

To illustrate how stainless steels can in the long run be the material with the lowest CO₂ emissions, the life cycle of two reusable water bottles are shown. 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.

Climate change and the production of iron and steel

More information about climate change and the production of iron and steel in general can be found on the worldsteel website.