Comment Log Display

(1)It appears that "bypass CO2" sent to flare in reference case is
treated as avoided emissions but I do not see where "bypass CO2" in
the application is accounted for (i.e., CO2 vented in the tailgas
and bypass CO2 in onsite energy should be emissions debt if treated
as avoided in the reference flare case.
Are the "bypass CO2" emissions accounted for in the pathway cases?

(2) Methane slip/ methane in tail gas:  Report footnote says the
tail gas can be flared or used for heat recovery or recycled into
biogas.  

The methane slip/ CO2 mixture is generally too lean to combust
alone and often must be mixed with natural gas or digester gas for
flare or engine or oxidized in a thermal or catalytic oxidizer.  
[Tail gas is (12% CH4 + 88% CO2)  if assume digester gas is 60%
CH4, 40% CO2 and there is 10% CH4 slip from a PSA].

Pathway needs to account for methane slip from upgrading process
(PSA is used in pathway document) as fugitive emission or as
oxidized CO2 (if tailgas is treated).  Recommend pathway report
discuss methane slip disposition and require appropriate treatment
or oxidation be part of pathway.