<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><DIV>Hi everyone,</DIV>
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<DIV>I have a question about how to account for emissions of biomethane. I'm wondering if they should be treated differently than emissions of fossil methane.</DIV>
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<DIV>Let's say that I own a coal mine whose operations result in the release of a ton of fossil methane into the atmosphere. To account for that in CO2e, I multiply the one ton of methane by 21 (if using the SAR GWP factor) and I report emissions of 21 tons of CO2e. In this case, I have released 0.75 tons of C as CH4 into the biological carbon cycle that would not have been there if not for human activity. If I capture and flare that ton of methane, I would avoid the release of 21 tons of CO2e, but I would still be responsible for the release of 2.75 tons of anthropogenic CO2 (if I'm not mistaken, one ton of CH4 yields 2.75 tons of CO2 when combusted). Although I'm still releasing anthropogenic CO2 into the atmosphere, I have at least avoided the release of an additional 18.25 tons of CO2e by capturing and combusting the methane.</DIV>
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<DIV>Now let's say I own a dairy farm whose lagoon produces a ton of biomethane. This methane contains 0.75 tons of C that were already in the biological carbon cycle. Human activity has increased the GWP of this carbon by converting it into methane, raising the GWP from 2.75 to 21 tons CO2e. Should this be accounted for in the same way as the release of fossil methane that introduces new C atoms into the biological carbon cycle? It seems to me there's an argument to be made that a ton of biomethane should be reported as 18.25 tons CO2e (i.e., the net increase in GWP) rather than 21 tons CO2e. If I capture this methane and combust it, I don't need to report the resulting CO2e as anthropogenic emissions because this CO2 would be considered biogenic. But I would still avoid the release of 18.25 tons of CO2e, for which I could possibly get credit. If I were to get credit for avoiding 21 tons of CO2e, would that be overcounting?</DIV>
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<DIV>Can someone point me to an IPCC or UNFCCC decision on this? </DIV>
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<DIV>thanks,</DIV>
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<DIV>Scott Murtishaw,</DIV>
<DIV>California Public Utilities Commission</DIV></div><br>
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