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This question is posted by the ecoinvent team on behalf of Romain Sacchi. 

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Hello,

I have a question regarding the role of steel scrap disposal in the steel production in the cut-off version of ecoinvent.

I was not able to obtain an answer form the V2 reports, neither from ecoinvent.

For the case, we would take the very simple example of the production of a 1 ton steel-made tower, without losses.

Ideally, assuming a system that recycles 90% of the post-consumer steel scrap (that’s about the assumed European conditions), I would naively expect such model representation.

But, much to my surprise, the real underlying modelling in the cut-off version of ecoinvent seems to be rather like what follows.

So, do I interpret correctly the fact that we have a system that draws 0,7t of iron scrap and only sends back 0,005t on the market?

And if so, does it means that the recycling rate is in fact rather close to 0,5% instead of 90%? The issue is that I cannot really find a documentation supporting the split figures in the market for scrap steel.

Thank you for your help.

Best regards,

Romain Sacchi

Dear Romain Sacchi,

Thank you for our email. Though the topic has already been addressed I hope my reply clarifies your situation a bit further. To begin with, the graphical representation you made envelops methodological inconsistencies that prevent an observer from the whole picture. You compare an ideal (closed) loop system which does not reflect the complexity of reality, with a cut-off system model which is a methodological approach that considers recycling to be a burden free process.
To directly reply your questions, the recycling rate is not 0.5% and by no means you can calculate a recycling rate given the fact "recycling" as a process is excluded due to the system model. If you are interested in the recycling rates of this process please have a look into the UPR (before linking and allocation) datasets of "steel production, electric" and "steel production, converter". The input of recycled material in those datasets is what matters when it comes to recycling rates.
On top of that, in case you wish to dive more into the details of the system models, I would direct you to following page (link) our website and have a look in the explanation we offer related to recycling process in the cut-off system model.

Best regards, 

Avraam Symeonidis, Data analyst, ecoinvent

Dear Avraam,

thank you for taking the time to answer.

I seemed to have understod that the recycling rate was mostly defined on the input side by the respective share of steel from eletric arc and oxygen blast furnace.

What drew my attention was rather the way the "end-of-life" was modeled by the "market for steel scrap" dataset. Almost all of it goes to landifll, and a minor share goes to incineration. That was what motivated my question really.

Best regards,

Romain

Dear Avraam,

In the Pre Listserv discussion, other matters were raised and i would appreciate your clarifying response on these questions also:

How is post-industrial recycled content treated compared to post-industrial recycled content - increases in post-industrial content imply greater waste and should penalise the product's profile, whereas post-consumer content has served humanity in one or more previous cycles and should benefit a product's profile?  (Post Industrial can usually be effectively modelled by expanding the system boundary).

Why is recycling excluded from the system model?

Thanks

Nigel Howard

Dear Nigel and Romain,

Regarding Romain comment: Following the recycling path of steel, “iron scrap” is the flow someone should follow in order find the recycling rates. “scrap steel” is rather a low quality waste that has no other fate than incineration or landfill.

Regarding Nigel’s question: Please let me rephrase and apologies for the confusion. Recycling is not excluded, it is cut-off from the producing activity. The recycling activity is then represented by activities "product name, Recycled Content cut-off" which come burden free. Recycling is under represented in ecoinvent, this has been the case since version 2, but it is a place where ecoinvent would like to extend their coverage. Finally, for post-consumer issues, in some cases, we distinguish post-consumer materials; not in the steel case though. In aluminium we do, for example.

Best regards,

Avraam Symeonidis, Data analyst, ecoinvent

Hi Avraam, you mentioned:

The recycling activity is then represented by activities "product name, Recycled Content cut-off" which come burden free.

I have some follow-up questions below:

1. If they are burden free, why we need these empty datasets in ecoinvent?

2. As an LCA practioner, if I have some waste metals that need to be recycled, shall I enter these "Recycled Content cut-off" flows in my inventory at all since they are burden free?

3. What about the transport of these waste metals from the generation point to the recycling facilities? Shall this also be ignored, and accounted as the burden of those who consume the recycled materials downstream, or they should be accounted for by transpotation activities in the waste metal generation process?

4. If I have a process that needs to consume some recycled materials, what is the best way to find the appropriate activities in ecoinvent that represents the recycled materials?

Say recycled concrete, if I search for "concrete" in ecoinvent online portal, and filtered the results with "recycl", I could only see waste treatment activitis, from which the reference products are still waste concrete rather than (useful) recycled concrete.

Additionaly, in Simapro, such waste treatment activities only even show up as options for material/fuel technosphere inputs.

Dear Shirley,

Thank you for your post. I will kindly re-direct you to our page where you can find information regarding the cut-off system model. Please have a look, as I think all your questions are already addressed there.

Best regards,

Avraam Symeonidis, Data Analyst, ecoinvent