HWD Difference in Steel Hot Rolled Coils vs steel low alloyed from ecoenvent.

Question

Hello everyone,

I am trying to model an LCA for a product that contains a large amount of steel. However, when I use the following ecoinvent flow and provider:

Flow: steel, low-alloyed, hot rolled
Provider: steel production, low alloyed, hot rolled | steel, low alloyed, hot rolled | EN15804GD, U-RoW

I get a significantly higher HWD (Hazardous Waste Disposal) and NHWD (Non-Hazardous Waste Disposal) compared to the EPD of AM/NS – 1 tonne Steel Hot Rolled Coils.

The difference is quite large. I am trying to understand what might be causing this difference.

Am I using the wrong dataset/provider or system model? Is there a more appropriate dataset for comparing HWD and NHWD with the AM/NS EPD?

Per kg steel	ecoinvent result	AM/NS EPD (A1-A3) (EPD-IES-0012007)
HWD	2.58 kg	7.7E-10 kg
NHWD	9.5 kg	0.027 kg

Answer 1

1E-10 kg of hazardous waste for 1 ton of steel is really really low I think. A simple google answer e.g. says this: 

I looked for the EPD and it even does not have any biogenic GWP (so they assume no cardboard or wood for packaging is used - downloaded from here https://api.prod.environdec.com/api/v1/EPDLibrary/Files/EPDs/d344b5f9-5084-4049-c36b-08dbfcbd856b/Documents).

Waste needs to be specifically modeled (in the database and / or foreground system) otherwise it is "evened out" in the calculation (not being an elementary flow), and I assume people are often happy if a low result is obtained without questioning whether it makes sense. And here, I would say, it doesn't, even though it is a verified EPD.

Hope this helps!

Andreas

edit: here results from our latest EN15804 database - not 2.58 kg per kg but 0.053 kg per kg (for one example steel):

I admit there are cases with higher values (0.61 kg for steel production w. silicon alloy) but this is then coming from the ecoinvent database and we need to live with that I think, for generic background data..

Comments

Hello Andreas,
thanks for the answer I agree that values in EPD are immensely low, however modelling 1 k hot rolled steel from ecoenvent results in 2.58 kg HWD and 9.5 kg NHWD, 1 EUR-flat pallet results in 1.56 kg HWD and 13.22 kg NHWD.
this is why I raised concern what am I modelling wrong??

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I think this was an issue in our earlier versions, I post a picture above (editing my post) with results from our EN15804 database, latest version (with ecoinvent 3.12) - here the  amounts seem in order.

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Hi Andreas,
I'm using Openlca 2.7, ecoenvent 3.12 and EN15804 add on version 2.
For the above process, I’m getting 0.926 kg HWD and 11.017 kg NHWD
I also tried completely removing all OpenLCA data from my system and reinstalling it, but I’m still getting similar results.

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Yes as said, this is then from the background database, ecoinvent - check in impact analysis e.g. where specifically the waste is coming from.
Uninstalling openLCA or deleting and restoring the database of course does not change the result (unless you somehow modified the database yourself before).
Way out: if this is important (I believe waste is always a proxy and as such not too important but this might depend on the client and study) model the core supply chain yourself, with own data.

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but how is it possible that for same thing your system giving different results than mine?

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what do you mean by 'same thing'?

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Hi Andreas,
sorry for delay in response, I had fallen sick.
Anyways I was talking about the snapshot you mentioned above grained oriented electric steel production I’m getting 0.926 kg HWD and 11.017 kg NHWD which is different than 0.053 HWD and 0.6392 NHWD.

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long thread ;). Indeed the specific amounts will vary by steel type
I made a simple google search and got this:
1. References for the Stated Figures
The metrics used to calculate the hazardous waste volumes in the previous responses are anchored in official environmental databases, federal statistical publications, and industrial processing reports:
•    Total Crude Steel Production: The Wirtschaftsvereinigung Stahl (WV Stahl) (German Steel Federation) Facts & Figures Report confirms that Germany’s annual raw steel production fluctuates between 35 and 40 million tonnes. According to reporting compiled by the Umweltbundesamt (UBA), roughly 11 million tonnes of this volume are generated via Electric Arc Furnaces (EAF) utilizing secondary scrap.
•    EAF Dust Generation Rates: The German Environment Agency (Umweltbundesamt) confirms that EAF processes generate 15 to 20 kg of steelmaking dust per tonne of steel.
•    Recycling and Waelz Kiln Mechanics: Global research tracking steel mill dust recycling details how the predominant treatment mechanism (the Waelz kiln method) extracts heavy metals. The resulting Waelz slag makes up 600 to 800 kg per tonne of processed dust. When failing local chemical leaching metrics, it requires Class III landfilling.
•    National Waste Context: Total hazardous waste metrics are cross-referenced with the Federal Statistical Office (Destatis), which tracks total German hazardous waste output at roughly 24 to 26 million tonnes annually across all industrial sectors.

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2. Hazardous Waste Deposited Per Tonne of Steel Produced
To find the exact mass of hazardous waste permanently deposited per unit of output, we map the volume generated against the total national production:
Stage    Metric Per Tonne of Total Crude Steel    Metric Per Tonne of EAF Scrap Steel
Gross Generation (Before treatment)    ~13.5 kg to 25.0 kg    ~35.0 kg to 50.0 kg
Net Final Deposit (After recycling)    ~1.3 kg to 4.0 kg    ~3.5 kg to 8.0 kg
Step-by-Step Calculation Breakdown:
1.    On a Gross Level (Generation):
If a steel plant combines blast furnace (primary iron ore) and EAF (secondary scrap) routes, the total industry generates 500,000 to 1,000,000 tonnes of total hazardous waste against a production baseline of 37 million tonnes of raw steel. This equals roughly 13.5 kg to 27 kg of gross hazardous waste generated for every single tonne of raw steel produced.
2.    Applying the Recycling Factor (80% - 90% Recovery):
Because 80% to 90% of these materials (primarily the zinc-heavy dusts and pickling acids) are successfully processed for secondary industrial markets, they are legally classified under recovery codes (R-codes) rather than disposal codes (D-codes).
3.    On a Net Level (Final Deposit):
This leaves 50,000 to 150,000 tonnes of final mineral salts, unrecyclable air-scrubbing sludges, and spent toxic furnace refractories that must be landfilled or cellared underground. Dividing this final remainder by the 37-million-tonne production baseline yields a final metric of roughly 1.3 kg to 4.0 kg of hazardous waste permanently deposited per tonne of crude steel produced in Germany.
and some references, older ones, plus this: about the amount of steel and slag deposited:
https://www.wvstahl.de/wp-content/uploads/202312_Facts_Figures_Steelindustry_Germany_WEB.pdf