What are the diffences of using the Ecoinvent "Unic Processes" database model over the "System Processes" version?

Question

Hi,

I've been using mainly the Cutoff System Processes version of the Ecoinvent database, but It's not clear to me what are the real diffences between the Cutoff Unit Processes and the System process versions of the database.

In my experience, when using the Unit processes version, the exported Excel file does not contain, e.g. the upstream flow contributions in a simple format, like the one from the System processes version does. I've only managed to export data that basically covers only the LCIs, i.e. only listing elementary flows. Is it possible to get the impacts-per-upstream-process -type of data from the Unit processes version as well?

Another thing I've noticed, is that the export process often freezes in the Unit processes version. I imagine this is due to too large Excel files (because of long lists of elementary flows).

I feel like this is a trivial problem, but I have not been able to find clear explanations for this.

Answer 1

You can export without the default provider. In case you export something with all default provider in the unit process database, it will export the whole database because nearly everything is linked with everything and this will blow up the export.

Disadvantages for using system processes: no inventories visible, no supply chain visible, no modification for creating new processes possible, no change of input provider possible, no contribution tree of the supply chain visible, no sankey diagram of the supply chain visible, no data quality or uncertainty of the supply chain possible, not really an advantage of calculation speed anymore as it was the case in the past (the newest openLCA is pretty fast also with ecoinvent unit processes and/or libraries), much larger system process database size which makes storage/uploads/backups/copying more time consuming and comes with more storage requirements, searching something in the database or modifying something over SQL is much slower due to the large amounts of exchanges existing, and so on...

I personally would never use the system process version when there is a unit process version available for the exact same data set and the exact same impact results.

Comments

PS: What I usually do is either doing a backup of the whole unit process database in zolca (takes a few seconds) or I export all foreground processes (the own created processes) in JSON-LD format and without selecting the option to export default provider (takes also only a few seconds).

When you re-import the own processes into the same Nexus ecoinvent version, the provider will automatically be set as it was before and also the linking between the own foreground processes will still remain set.

Another option is to work with the new feature of the ecoinvent unit process library where the foreground and background is separated.

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Thank's for your answer! This helps me understand the whole thing a little better. However, would you like to expand a bit more how your LCIA workflow goes with the Unit process db? If you export the foreground processes in JSON-LD format, at which point, and how, do you calculate the LCIA results and how do you treat them?

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The import and export in JSON-LD I only meant when you want to share data sets, because you don't need to export the whole database containing all background data sets.

When you work in ecoinvent, you can always do an LCIA calculation in the unit process database and export the LCIA results via copy/paste or via saving them as results or via a report. You can also store your calculated LCI inventory as a result data set or as a new system process data set, so that you have all your aggregated/calculated elementary flow inputs and outputs in one process.

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Ok, thank you for the clarification! Now I think I understood :)