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Hi, I am getting all my impact analysis result as zero. So i checked with the questions asked here and made sure I am using compatible database and LCIA pack. I am using the USLCI database and TRACI 2.1 for impact assessment. But still I am getting zero. Can anyone tell me what could be the other reasons?

My input is Al sheet and electricity and output is an Al formed part and I have chosen Unit process. I am attaching images here for better understanding. I would appreciate any help. Thanks

in openLCA by (210 points)

1 Answer

+1 vote
by (2.4k points)
Two things to check: Which version of TRACI are you using? The USLCI (assuming you are using a recent version) uses the Federal Elementary Flow List. You need to also use TRACI that uses the Federal Elementary Flow List. Both should be pulled from the federal LCA commons: https://www.lcacommons.gov/

Second thing to check is your product system. Is it correctly linked to upstream processes on the model graph? The process in your screen shot above does not have any elementary flows that are tracked by TRACI so you will not see any direct impacts from the GMAW process itself.
by (210 points)
Thanks for the reply. So I have downloaded both now from the link you provided and calculated it. But now I am getting all the impacts Negative!
2. how do I make sure whether I have correctly linked it to the upstream or not? I have linked the inputs to the Provider and checked the 'auto link process' and 'prefer default providers' while creating the product system. Also in the model graph I can see they are linked.
by (310 points)
If you use the latest version of USLCI from the Federal LCA Commons, you should not have all negative impacts, though as @byoung mentions, you will also need methods adapted to the Federal Elementary Flow List (FEDEFL), to which the USLCI converted in 2019. The USLCI, FEDEFL and the FEDEFL-adapted methods are available on the Federal LCA Commons for download and import, e.g., into your openLCA desktop application (e.g., for methods, https://www.lcacommons.gov/lcia-methods-without-flows). Please see the USLCI GitHub Support Content (https://github.com/uslci-admin/uslci-content/wiki) and/or the NREL USLCI Quick Help YouTube video series (https://www.youtube.com/playlist?list=PLmIn8Hncs7bFUOyXZNGXwG4LtdoTfLz6Q) for details on USLCI Database versioning, using FEDEFL-adapted methods, and running calculations on USLCI in openLCA.
by (210 points)
Hi thanks a lot for replying but i am still having the same result and very confused what to do. I have been through the links and YouTube tutorials as well. Can I ask a favor? Could you please check the link that I have provided to make sure that I have downloaded the correct/latest repository?

For USLCI,     https://www.lcacommons.gov/lca-collaboration/National_Renewable_Energy_Laboratory/USLCI_2021_Q1_v1/datasets

For TRACI,      https://www.lcacommons.gov/lca-collaboration/US_Environmental_Protection_Agency/TRACI/datasets
Thanks again
by (310 points)
For TRACI, you have the correct link for the latest version. However, for the Commons (of which, USLCI is a repository), you need the Federal Elementary Flow List (FEDEFL)-adapted version of TRACI. This link: https://edg.epa.gov/metadata/catalog/search/resource/details.page?uuid=https://doi.org/10.23719/1522413 can be accessed via the Commons home page - lcacommons.gov under 'Documentation>Methods without flows' - the link posted above and the USLCI GitHub Support Content (https://github.com/uslci-admin/uslci-content/wiki/FEDEFL-Adapted-LCI-&-LCIA-Methods) detail why the 'no-flows' version and caveats for use. Let me know if you have further questions.
by (210 points)
Thank you so much for your reply. I downloaded the FEDEFL TRACI version, and still getting negative results. Do you think it might have to do something with the 'Autolink process' ? Because I was trying to figure out what  it does by checking the  Autolink process and figured out that removing 1 or 2 upstream processes supply chain, it gives me positive impact results?! Though I removed those supply chain randomly, not really understood it. I wanted to add  Screen shots from my analysis here but couldn't add image in comment
by (140 points)
First thank you for this post.  I have gone through the same exact process as you except just with the passenger car, gasoline powered process, made it a system process and calculated.  I was getting zeros so reloaded the impact assessment methods from github and rand it with traci 2.1 and now I'm getting negative numbers for all categories.  I chose this process because I know what answer to expect for Global Warming Imparct somewhere around .365kgCO2e/mile, the answer I get -9.18kgCO2e/mile.   The proportions in the contribution tree seem to make sense with petroleum refining the larges (except its negative) impact followed by some transportation.
by (310 points)
I did just apply FEDEFL-adapted TRACI v2.1 on the USLCI_2021_Q1 process: "Transport, passenger car, gasoline powered" and obtain GWP of 0.18414 kg CO2 eq/p*km (leaving all calculation settings as default. You definitely want to 'auto-link processes' to get the Scope 1-3 emissions factor (including supply chain emissions for production & delivery of fuel) in one result. If you uncheck this box in calculation set-up, you will only get the Scope 1 (direct combustion) emissions factor result (0.1493 kg CO2 eq/p*km). The problem you are describing makes me wonder if your update of the USLCI Database failed (see versioning instructions video at:  (https://www.youtube.com/playlist?list=PLmIn8Hncs7bFUOyXZNGXwG4LtdoTfLz6Q). This can happen if you import the new USLCI into the old USLCI and don't follow through with all the import wizard settings windows where you can specify 'overwrite with newer datasets' in openLCA.
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