LCIA compressed air

Question

Hello openLCA team,

i am modelling the process chain of an car seat. In some processes, I use the flow “compressed air” (production mix, 7bar, high efficiency and low power consumption – GLO) from the elcd 3.2 Database. (To provide 1m3 compressed air, 0.342 MJ electricity is used)

When I do the Life Cycle Impact Assessment, there are no contributions to any impact category regarding compressed air. It does not matter if I use 1m3 or 1.0 E7m3 compressed air. I thought there have to be contributions to impact categories based on the Input flow, which is just electricity for compressed air.
Or do I have an error in reasoning?

Best
ttecked

Answer 1

Hello and welcome,
the flows from your processes need to be recognised by the LCIA method. Which method did you choose, what do you see in the impact analysis tab which shows the contributions of flows to impact categories? I am adding an example from another calculation, maybe this is helpful. Also, check the impact method, does it contain flows that you use in your processes (or, that are used in the ELCD database processes)9?
Best wishes,
Andreas

Comments

Hello Andreas,

thank you very much for your quick answer and your help. I chose the CML (baseline) [v4.4, January 2015].

To identify my problem I created an “test” process named “test Druckluft Herstellung” with the reference flow “test Druckluft”.
Input is just the product flow "compressed air" 1m3 from the elcd database. Output is the product flow "test Druckluft" 1m3

After that I build a product system “test Druckluft Herstellung”. The model graph is as attached (file 1)
 
When I calculate this product system (use the CML baseline) I get these results (file 2 and 3)
 
When I also connect the process electricity as seen in the model graph (file 4) and press the bottom calculate I get the following message (file 5)
 
I did this kind of scheme of the “test” process also with “Stahl Herstellung”, “PP Herstellung” etc. and it works quite well!

The Input of the process “compressed air” from the ELCD database is just electricity (Dummy electricity). Therefore, no flows are deposit.
 
Maybe the problem is the Dummy Process electricity, because there are no input flows deposited?

Best wishes

ttecked

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ok sounds good, but you lost me: the last product system, with the dummy electricity process, does not contain any elementary flows nor other input flows, and has only the output product? These "trivial" product systems cannot be calculated in openLCA, which is probably the explanation of your error (in last screenshot)?