ILCD Midpoint+ providing unneccesary carbon credits?

Question

Hi openLCA team,

I am flagging an issue that initially was brought up in a comment here: https://ask.openlca.org/1014/when-openlca-incorporate-updated-methods-described-guide?show=1014#q1014. I couldn't add screenshots in the comment, so I'm starting a new thread.

I am also getting negative results for agricultural products using ILCD Midpoint+. I believe the issue is a (spurious?)  -1 CF for "carbon dioxide, in air" in the "resources, in air" category for ILCD Midpoint+ in openLCA. The Midpoint+ results do not match results using IPCC 2007 in openLCA, ILCD Midpoint in openLCA, ILCD 1.0.8 in ecoinvent 3.5 (from ecoquery), or IPCC 2007 in ecoinvent 3.5 (from ecoquery). See screenshots below for LCIA results for "sugar beet production | sugar beet | cutoff, U - CH" in the ecoinvent 3.5 cutoff regionalized database from nexus.

The first screenshot is Midpoint+.

This has tremendous implications for ag product LCAs. I want to use the Midpoint+ method but do not feel comfortable doing so given these differences. Please advise!

(openLCA 1.7.4 with ecoinvent 3.5 cutoff regionalized and the openLCA LCIA methods 2.0.3. on a Mac OS High Sierra.)

Best,
Nicole

Answer 1

Hi, I don't know the midpoint+ method so this is just a guess as noone else has answered yet - maybe it will at least be an idea to consider. It looks like the methods that ignore the CO2 are basically assuming that it will return to atmosphere and not characterizing it / treating it as neutral, while the midpoint+ method is including a separate extraction from air  (i.e. the -1 factor, relating to growing the beet) and so an additional flow like "abiotic carbon emissions to air" or something (that presumably would have CF+1 for that method but be zero in the others) would be needed within the system to make it the same. If you do work it out, it'd be interesting to know.