Issues with Monte Carlo simulations even with latest Ecoinvent 3.9.1

Question

I am still having issues when running a MC simulation, as I still get very different values, for example as attached on the picture here, I get unexpected values for 1 kg of barley produced for a process directly from the database (barley production | barley grain | Cutoff, U - ES): https://ask.openlca.org/?qa=blob&qa_blobid=2848088915307602355

I know there has already been a post about this issue here "How to carry out a Monte Carlo analysis correctly using the ECOINVENT 3.9.1 database", however I did update to the latest OpenLCA version, and I did upload the latest Ecoinvent 3.9.1 database from the Nexus. 

Thanks!

Comments

https://www.openlca.org/uncertainty-corrections-for-ecoinvent-3-9-1-en15804-add-on/

The newest databases with uncertainties corrections have "n3" and "20230629" inside the file name.

Answer 1

Which database (file name) are you using and which method? I cannot reproduce your wrong Monte Carlo Simulation results with our latest ecoinvent release. For example, when using our latest release of 3.9.1 from Nexus (July) and the unit process database with the cutoff system model and 100 iterations, I get the follwing: mean 0.696, standard deviation 0.046, median: 0.693 kg CO2-eq, using the ecoinvent implemented EF 3.1 method. 

Maybe double-check your database version. The latest database versions, including the uncertainty corrections for Monte Carlo Simulation, are marked with n3 (Nexus version 3) and the date of correction 20230629 inside the .zolca file name of the databases.

https://www.openlca.org/uncertainty-corrections-for-ecoinvent-3-9-1-en15804-add-on/

Comments

Hello,

Thank you for your answer! I think that the issue is that OpenLCA Nexus (at least mine) does not have access to this n3 version, as when downloading the databases again, their names do not show n3 but:
- ecoinvent_391_apos_upr_n2.zolca
- ecoinvent_391_cutoff_upr.zolca
- ecoinvent_391_cutoff_upr_regionalized.zolca
- ecoinvent_391_consequential_upr_regionalized.zolca

etc.

Could it be that I am not looking at the right download section of Nexus (I don't see where else other than under "Purchased databases" - "Ecoinvent 3.9.1", or that the latest databases were not uploaded ont he Nexus?
Many thanks

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Hi. I have also tried to reproduce Sophie's 1kg barley and get the same answer; on a different machine. I downloaded ecoinvent v3.9.1. today to see if this issue had been solved, but when clicking on the ecoinvent 3.9.1 on the nexus I do not get n3 or 20230629 inside the .zolca file name. I suspect I only have access to the older version of 3.9.1. Could you send me the latest files? Many thanks

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We are using "regionalised cut off" 3.9.1

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In openLCA2 you can simply click "Regionalised calculation" to get elementary flows with their corresponding location in the results, which makes an extra "regionalised" version of a database kind of obsolete and you can use Cutoff, Consequential or APOS (without the extra regionalised version). For the impact assessment in openLCA2, you can easily add as many regionalised characterisation factors as you wish for each unique elementary flow, without the need for a "new" flow for each location. You can add or copy/paste the unique flow inside the characterization factors table and change the factor and the location.