Flipping sing of elementary flow after LCIA calculation, land use category

Question

In this is inventory results of the process: citric acid production | citric acid | Cutoff, S

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I checked and there are 3 land use inventories that get flipped. (from input become output with a negative sign)  after calculation is run

• Occupation, dump site
• Transformation, to forest, unspecified
• Transformation, to dump site

looking at the process inventory and then to the "inventory results" after calculation these flows from input do become outputs with a negative sign. 

This is causing some issues in Land Use Methods I am calculating from Ecoinvent DB. while in the system process this is causing negligible changes in complex unit tree systems this difference is quite high.

I am using a dedicated python script to run multiple calculation and comparing them with what I get from open LCA. I get results that are equal openLCA to all indicators but not land use that is exploiting the natural flows mentioned above.

I am unsure why this flips happen and if this is the correct calculation behavior or not. it seems to me it is not.  but in case then in Open LCA all LCIA methods usoing the land use flows are not computing properly

Looking forward to hearing from you

thank you in advance

Kind regards

Luca

Answer 1

Hi Luca,

from your company name I assume you are referring to an extended version of ecoinvent 3.6 you obtained from someone who in turn received it from us in a special smaller project. Our ecoinvent 3.6 version had indeed an issue with some land use (transformation and occupation) flows being pushed to the "other side" (input become output with a negative sign, as you say), caused by our then introduced waste modeling. For the inventory calculation, this does not matter, but for LCIA, you need to know of course the "orientation" of the elementary flows.

In our ecoinvent 3.7, this issue is fixed.

Best wishes,

Andreas

Comments

Thanks for the reply

regards