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I am using openLCA 2.0.3 to analyse the CO2 emissions (GWP) of a proposed commercial scale plant. For my impact assessment method I am using IPCC 2021.

I am inputting my CO2 emissions for each stage of the process as kg outputs per one unit (ie pump, for example). Ie I essentially end up with 'x kg CO2 per y units of item'. This is working well for items which are measured in units such as kg, L, etc, however I am running into some trouble with items which are measured in terms of area (m^2).

For example, say I need 1000 m^2 of solar panels in my final plant. I have created a process which has an output of 1 m^2 solar panels and 2 kg CO2. This then gets scaled up into the final plant.

Unfortunately, when I go to run my calculations, I am finding that rather than simply considering the emissions as '2 kg CO2/ 1 m^2 solar panels', the program is doing something very weird and saying that, say, -5000 kg CO2 emissions are happening from this part of the process, even though my expected number is +2000 kg CO2. This is only happening to flows which are measured in terms of area.

(BTW, I have a cropped screenshot of my actual program for context but can't seem to attach it to this post without a URL??)

Is there some way to get around this issue and get my program to recognise that area units are simply a measure of quantity, and have nothing to do with emissions??

Thanks in advance :)

in openLCA by (140 points)
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by (3.3k points)
Hello SarahWright,
To upload an image, click on _Image_ in the question editor and select the _Upload_ tab.

2 Answers

+1 vote
by (116k points)
Hi, this is of course typically not really linked to the unit (unless you have set a negative conversion factor) but linked to where flows with this unit are used in the inventory - so a screenshot would be useful ;)
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by (3.3k points)
use the impact tree function to drill down and see where the negative emissions are. Especially look out for infinately looping dummy processes or a process with over 100% contribution.