Avoided emissions double counting in manure/organic waste RNGF pathway

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1 week 1 day ago #308 by samdwright
Good afternoon,

Under the two CRNG alt fuel pathways for manure (input columns BD and BE), row 247 acts as the input cell for manure mass per GJ of RNG. When these two columns are made identical (as well as the fertilizer coproducts made equal), one would expect the avoided emissions to be the same. However, this is not the case, with the organic waste pathway still providing a much lower CI. That being said, I found if I changed cell F47 to 0 (the organic waste methane emission factor), the two pathways would be identical. Is there a reference in the organic waste RNG pathway that should be connecting BE246 to F47 that is instead connecting BE247 to F47? Avoided emissions for the manure (referencing Coprods cell A45 for manure methane emissions) are already included in purple part of the formula below, which matches a similar part of the formula used on the Manure/Grass AD pathway. Even if I set Input F47 identical to Coprods A45, I still get a different number due to the green part of the formula below counting the avoided emissions twice (one with a GWP of 25, one with 22.3)

The displaced emissions formula for CRNG from organic waste: (Upstream Results HHV BO19)
=-Coprods!AD120*'Energy Use'!K57- 1/'Fuel Char'!$K$143*Input!F47*GWP!C10*1000*'Alt Fuel Prod'!BW28*'Energy Use'!K$57*(1-Input!F45) -'Alt Fuel Prod'!BW25*Coprods!A45*GWP!B10

This forum post states that BE246 and BE247 should be used as the organic waste and manure mass inputs respectively for anaerobic codigestion. Shouldn't F47 have no impact on the displaced emissions if BE246 is 0?

Thanks a bunch, pictures of my inputs and results are attached. In the case with the same results, F47 is set to 0. In the case with different results, F47 is set to 50. Coprods A45 is set to 3.5 for both, and fertilizer coproducts match for both as well.

Cheers,
Sam





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1 week 14 hours ago #309 by doconnor
Thanks Sam
I came across this a couple of days ago. We will fix this and post a revised model next week.
Regards
Don O'Connor

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1 week 14 hours ago #310 by samdwright
Thanks Don, much appreciated!

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3 days 15 hours ago #311 by rdo
I've just posted the updated version 5.01g. It has this fix. Thanks for pointing it out.

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