[ Sustainability ]
[ Sustainability ]
the production of stainless steel , we will identify the CO 2 emissions from the categories previously defined as Scope 1 , Scope 2 and Scope 3 .
• Scope 1 emissions The current scrap-based producer average is 0.41 tonnes of CO 2 per tonne of stainless steel produced . 85 % of the producer results sit ( normally distributed ) in the range 0.20 to 0.50 tonnes of CO 2 per tonne of stainless steel produced .
• Scope 2 emissions The current scrap-based producer average is 0.39 tonnes of CO 2 per tonne of stainless steel produced . The figure has dropped from the average figure reported in 2023 which was 0.45 . Changes in the regional energy grid mixes have positively impacted Scope 2 emissions , and thereby , the figure has started to become lower than was historically seen .
• Scope 3 emissions Scope 3 emissions cannot be defined in the same manner . There is a linear relationship between the amount of recycled content ( scrap stainless steel and scrap low alloy steels ) charged and the magnitude of Scope 3 emissions . The higher the recycled content , the lower the Scope 3 emissions . Furthermore , the available data only covers recycled content ( also known as the scrap mix ) between 40 % scrap and 97 % scrap , which yields the following Scope 3 emission levels .
• 50 % scrap ; 2.90 tonnes of CO 2 per tonne of stainless steel produced
• 75 % scrap ; 1.65 tonnes of CO 2 per tonne of stainless steel produced
• 85 % scrap ; 1.15 tonnes of CO 2 per tonne of stainless steel produced
NPI production currently produces emissions in the average range ( designated by geographical source ) of 60 to 85 tonnes of CO 2 per tonne of Nickel produced . This means that if NPI is used to make an 8 % Nickel containing stainless steel , the increase in Scope 3 emissions ( when compared to a 40 % scrap mix ) associated with this route will typically be between 4.0 and 6.0 tonnes of CO 2 per tonne of stainless steel produced . NB : for comparative purposes , a 40 % scrap mix with zero NPI delivers a Scope 3 emissions level of 2.80 tonnes of CO 2 per tonne of stainless steel produced .
Life cycle emissions As stainless steels are reusable , durable , and corrosion resistant materials offering low maintenance needs and a long service lives it is important to consider life cycle emissions , ie ; all the Carbon-equivalent emissions released during the different phases of the product life cycle . It is also needed to determine the emissions frequency at each stage over the life cycle , covering material production , material transport , material fabrication , fabricated product transport , installation , maintenance , replacement , and recycling .
Material life cycle emissions Figure 3 below shows the CO 2 production and maintenance emissions for stainless steels , carbon steel and aluminium . Two different stainless steels 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 CO 2 tonnes emitted per tonne of material produced plus any CO 2 emissions associated with regular maintenance needs . The Carbon steel emissions increase every 10 years due to regular maintenance needed to supress corrosion . Stainless Steels and Aluminium emissions do not increase as their passive films prevent the need for regular maintenance . The CO 2 emissions data and associated included recycling credits are industry supplied figures . The Aluminium data has been adjusted downwards to reflect the fact that the density of Aluminium is about one third that of carbon steel and stainless steels .
Example : the life cycle of water bottles It is possible to illustrate how stainless steels can , in the long term , be the material offering the lowest CO 2 emissions . The life cycle emissions of two reusable water bottles are shown below . The Stainless Steel water bottle has higher CO 2 production emissions , but because this bottle will last at least 20 years and a PET * bottle will need to be replaced at least 10 times in these 20 years , the stainless steel water bottle will ultimately be the lowest emitter of CO 2 .
38 Stainless Steel World December 2024 www . stainless-steel-world . net