+1 vote
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Hello,

I'm trying to model a greenhouse tomato production. I've found a process that looked pretty much like what I wanted to model: tomato production, fresh grade, in heated greenhouse. When I look at the results in the contribution tree, I find that the ecosystem quality total percentage aren't adding up to 100% but to more than 130%. I've been told that it may be because this process consume heavy metals so there would be negative fluxes that would explain this difference. But I wondered why I couldn't see these negative fluxes in the contribution tree?

In short, I want to know how to plot the relative importance of each process in the total score of a category if I don't have the real 100%.

I'm using version 1.7.0.

Thank you for your help.

in openLCA by (130 points)
edited by
by (22.7k points)
Adding information to the question on what method you are using will make it more likely that users are able to help.

1 Answer

0 votes
by (38.1k points)

Yes this is indeed caused by negative flows; which version of openLCA are you using? We fixed this recently, you should see a negative contribution in the end with the rest of the first main contributions being > 100%, similar to here:

by (130 points)
I'v downloaded the latest avaible version (1.7.4) and I still have the same problem.
by (38.1k points)
edited by
..and do you see the negative contribution as in my screenshot? Thank you.
edit: I calculated now myself, for both tomato in heated greenhouse, in cut-off, with the ecoinvent method package, ReCiPe HA endpoint, and get 100% for both, and no negative contributions.
by (130 points)
No I do not get negative fluxes as in your screenshot. However, I use the Impact 2002+ endpoint method. Maybe this could explain why I still have the problem? I did a tetst and ran the same product with the ReCiPe HA endpoint and got similar results as you.
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