EPD vs Ecoinvent - Variability in carbon footprint of stainless steel

LCA Data & Tools
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Hello together

I hope I am adressing this question in the right forum:
To calculate several categories including steel, we use Ecoinvent Database.

Now for Stainless Steel, Ecoinvent latest Database give me the following information:
'steel production, chromium steel 18/8, hot rolled - RER - steel, chromium steel 18/8,
hot rolled - IPCC GWP 100a: 5.11 kg CO2-Eq

During my search on the internet, I have found the EPD Calculation of Aperam for 304:

On Page 13, they show a calculation of the LCIA incuding steps A1-A3 / C1-C4 and D
This Calculation give me a value of 1958 per tonne of material. As you can see, there is a massive gap. Do I miss something ? Do I compare completely different things ? Or is Aperam simply producing their steel on a very low emission way compared to the average of europe ?

Thank you for your feedback

2

Both of these values are within a reasonable range for steel. There really can be these large differences between steel from different producers based on the technology they use. Generally, it comes down to the steel coming through a Basic Oxygen Furnace (BOF) vs Electric Arc Furnace (EAF) route and the amount of recycled content in the steel. See the Carbon Smart Materials Palette for a succinct overview of this. The difference in your case is that the ecoinvent data point represents a regional average, so it looks like most of the stainless steel in Europe may come via the BOF route. The EPD is for a single EAF facility, as noted on the EPD.