Hello,
I am currently investigating the environmental impacts of different end of life options for plastic waste using the ecoinvent database. The analysis of the recycling option gave somewhat confusing results. As the goal of the study is the comparison of different end of life options, the input/output flows should be the same for all options. For this reason, the plastic granulate produced by the recycling process should be compensated by a credit of plastic granulate from virgin production.
However, when processing the parameters for the different flows, the results are the opposite to my expectations.
- polyethylene recycled: 1kg
- polyethylene virgin: -1kg (credit)
It seems that in order to have the expected results (Impact_RecyclingWithCredit = Impact_ProductionFromRecycledPlastic - Impact_ProductionFromVirginProduct), the parameters for the outputs must be inverted (which seems counterintuitive):
- polyethylene recycled: -1kg
- polyethylene virgin: 1kg
Can you explain why that is ?
Thank you in advance.
