How can i put outputs in the activity browser ?

[AIRPLAY9]

I'm new to Brightway and I'm using the Activity Browser to model a recycling process that consists of several inputs and outputs. I've put the inputs in the Biosphere Flows section, but I don't really know where to put the outputs. I've tried putting the outputs with a minus sign in the same section, but the LCA calculations come out negative. Can anyone help me? Thanks.

[marc-vdm]

Perhaps check out the tutorial to learn how to do LCA in Activity Browser. Hope that helps!

If the tutorial doesn't specifically answer your question, please let us know what information you're missing and would like to know still

[AIRPLAY9]

I have read that tutorial carefully these days, but it does not answer my question. I am trying to model the recycling process of photovoltaic modules for several top global companies and compare. In that inventory I have the inputs (electricity or liquefied natural gas) and the outputs (cables, junction box, ethylvynilacetate...), you can see them in the image I attach. I have tried putting the outputs as negative in the tecnosphere flows section, and in the tree diagram you see something that in principle is correct, the inputs come in and the outputs come out, but when doing the lca with any impact category, I get results negatives. That's why I don't know how to do it right and I'm desperate. Thanks in advance.

[marc-vdm]

That looks like a multifunctional process. Does this discussion help?

[AIRPLAY9]

Yes, it is a multifunctional process. I think I understood what you explained, but I would have to do it in AB to check it. However, since AB does not allow these multifunctional processes, is there a way to program it with Brightway to calculate the LCA? I am very new.

[AIRPLAY9]

One more question. I just had an idea. If I were to create an activity where I put all the inputs and the outputs into the technosphere? Clearly, the sense of flow is not being respected, since all inputs and outputs are considered as inputs, but is it mathematically valid to perform the LCA?

[marc-vdm]

In the multifunctionality discussion I shared an example database, this database also has an example for a multifunctional recycling process. You can import that into AB to have a look.

Clearly, the sense of flow is not being respected, since all inputs and outputs are considered as inputs, but is it mathematically valid to perform the LCA?

If I understand your question correctly, this should work yes. Note that the mathematical model of LCA does not guarantee correct mass balances, in contrast to e.g. MFA.