Forum for ecoinvent Version 3

Recycling processes in ecoinvent v3

Written on: 10.07.2019#1

Author:
david.turner

Question from Eva Risch via the LCA Discussion List.

 

I would like to compile consistent inventories with regard to cut-off allocation rules. For recyclable materials such as aluminium, steel or copper: in Ecoinvent v3 database (in “Ecoinvent unit processes”) there are some old v2.2 recycling processes that have been converted (eg "Recycling steel and iron/RER U" and these are empty - which is in line with the cut-off system modelling). But there are also v3 processes describing the waste treatment market (eg "Waste reinforcement steel {CH}| market for waste reinforcement steel | Cut-off, S" - which include recycling activities: “Waste reinforcement steel {CH}| treatment of, recycling | Cut-off, U” that are not empty (contains energy for dismantling); and other end of life activities (treatment in sorting plant and collection for final disposal..):

 

Process localisation (SimaPro category)

Process name

Description

Ecoinvent unit processes v2

Waste treatment - Recycling

Recycling steel and iron/RER U

Empty

ecoinvent v3

Waste treatment – Recycling – transformation

Steel and iron (waste treatment) {GLO}| recycling of steel and iron | Cut-off, S

Empty

Waste treatment – Construction waste - transformation

Waste reinforcement steel {CH}| treatment of, recycling | Cut-off, U

Not empty, includes energy for dismantling

 

Why both types of processes are proposed in Ecoinvent v3? How to correctly model the steel used in my inventory, if it is say, recycled at 95%?

 

Thanks in advance,

Kind regards,

Eva

Written on: 10.07.2019#2

Author:
david.turner

 

In the context of the cut-off system model (for more information, please refer to the ecoinvent website) the secondary use cycle of a material starts at the point of waste collection (e.g. steel scrap collected from households), while the point of cut off is the recycling activity. Hence, the supply chain for secondary materials (produced through recycling activities) includes their collection and recovery (sorting and dismantling), which is why secondary products are often not wholly burden free. For steel, this means that the collection and recovery of steel scrap would be included but that the recycling of recovered steel scrap in an electric arc furnace is “cut-off”.

 

The products “waste reinforcement steel” and “steel scrap”, that you mention in your email, are both wastes. Waste reinforcement steel is treated through one of three activities: “treatment of waste reinforcement steel, recycling”, “treatment of waste reinforcement steel, collection for final disposal” or “treatment of waste reinforcement steel, sorting plant”. The system boundaries of the inventories includes on-site energy use for dismantling and sorting, plus transport and disposal. No bonuses or burdens are given for recycled material and no secondary products are available; i.e. the system boundary cuts off the recycling process entirely. Similarly, “scrap steel” can only be treated by either landfill or incineration; it never goes to recycling.

 

So how can secondary steel products be included in an inventory? The collection and recovery of ferrous scrap is included in the ecoinvent database through the “iron scrap” recycling chain, not “steel scrap”. This is, obviously, not ideal and can easily lead to confusion: despite being ostensibly the same, “scrap steel” is a waste that is sent for disposal; “iron scrap” is a recyclable that is collected and recovered for recycling.

 

The collection of “iron scrap, unsorted” is represented by the activity “iron scrap, unsorted, Recycled Content cut-off”. This is then sorted and pressed in the activity “sorting and pressing of iron scrap”, which produces “iron scrap, sorted, pressed”. The sorted iron scrap is then made available, burden-free, for its secondary use cycle by “iron scrap, sorted, pressed, Recycled Content cut-off”. “Iron scrap, sorted, pressed” is consumed, burden free, by the activities “steel production, electric, chromium steel 18/8” and “steel production, electric, low-alloyed”, which represent the production of steel products in an electric arc furnace from ferrous scrap.

 

How one might include an input of 95% recycled steel: 95% of the steel used in your inventory should be “steel, low-alloyed” or “steel, chromium steel 18/8”, supplied directly from the activity “steel production, electric, low-alloyed” or “steel production, electric, chromium steel 18/8”, respectively. The remaining 5% can come from “steel, low-alloyed” or “steel, chromium steel 18/8” that is supplied directly from “steel production, converter, low-alloyed” or “steel production, converter, chromium steel 18/8”, respectively.

 

Written on: 11.07.2019#3

Author:
eva.risch

Dear David,

Thank you for your answer and detailed explanations.

Our issue is not about how to include secondary products in our inventory: we use the global market process for steel (“Steel, unalloyed {GLO}| market for | Cut-off, S) that already includes some scrap iron in “Steel production, converter, unalloyed”).

Indeed, our concern is about how to consider the end-of-life of steel, including recycling. In our waste-treatment of steel (outputs to technosphere), we would like to adapt the end-of-life of steel in France by sending e.g. 95% to recycling and 5% to treatment.

  1. For treatment we chose “Scrap steel {Europe without Switzerland}| market for scrap steel | Cut-off, U”, which includes transport, landfill and incineration. 
  2. For recycling we chose “Steel and iron (waste treatment) {GLO}| recycling of steel and iron | Cut-off, S” which is an empty process (due to cut-off rules).

Also, given the information on the Ecoinvent website and in your reply, we understood that according to cut-off rules, from the waste-producing side (our situation) the recycling process is “cut-off” and we only consider transport to, and dismantling (if necessary, as in “Waste reinforcement steel {CH}| treatment of, recycling | Cut-off, U” for waste reinforcement steel) in a waste treatment facility.

Do you think the above is correct? If so, to ensure consistency with the treatment line 1 (5% of steel), should we add transport in the recycling line 2 (transport to recycling facilities for the 95% of steel)?

Cheers,

Eva 

Written on: 11.07.2019#4

Author:
david.turner

Dear Eva,

 

Iagree with your choice of activities in both cases. However, I think there has been some confusion. You write:

 

"Also, given the information on the Ecoinvent website and in your reply, we understood that according to cut-off rules, from the waste-producing side (our situation) the recycling process is “cut-off” and we only consider transport to, and dismantling (if necessary, as in “Waste reinforcement steel {CH}| treatment of, recycling | Cut-off, U” for waste reinforcement steel) in a waste treatment facility."

 

To be clear: to be consistent with the philosphy of the cut-off system model, the burdens of collecting, sorting (dismantling) and transporting iron scrap that is collected for recycling are allocated to the consumer of that iron scrap. The producer of the iron scrap that is collected for recycling should not recieve any burdens from producing that by-product.

 

Based on this, here are some general recommendations for modelling ferrous scrap inputs/outputs in product systems (note that activity and exchange names may vary in SimaPro as they use their own naming convention):

 

Input from technosphere

 

"market for iron scrap, sorted, pressed" - where you have an input of iron scrap for recycling (in an electric arc furnace).

 

"steel, low-alloyed" from "steel production, electric, low-alloyed" - where you have an input of steel produced from recycled iron scrap (note that chromium 18/8 steel is available as well).

 

By/products/wastes

 

"iron scrap, sorted, pressed, Recycled Content" - where you have an output of iron scrap for recycling. 

 

"market for steel scrap" -where you have an output of iron scrap for disposal.

 

I hope this is helpful to you. Let me know if you have any follow-up queries.

 

Best,

David