§ 98.73
Calculating GHG emissions.
You must calculate and report the annual process CO2 emissions from each ammonia manufacturing process unit using the procedures in either paragraph (a) or (b) of this section.

(a) Calculate and report under this subpart the process CO2 emissions by operating and maintaining CEMS according to the Tier 4 Calculation Methodology specified in § 98.33(a)(4) and all associated requirements for Tier 4 in subpart C of this part (General Stationary Fuel Combustion Sources).

(b) Calculate and report under this subpart process CO2 emissions using the procedures in paragraphs (b)(1) through (b)(5) of this section for gaseous feedstock, liquid feedstock, or solid feedstock, as applicable.

(1) Gaseous feedstock. You must calculate, from each ammonia manufacturing unit, the CO2 process emissions from gaseous feedstock according to Equation G-1 of this section:

$ER30OC09.034$
Where:
CO2,G,k = Annual CO2 emissions arising from gaseous feedstock consumption (metric tons).
Fdstkn = Volume of the gaseous feedstock used in month n (scf of feedstock).
CCn = Carbon content of the gaseous feedstock, for month n (kg C per kg of feedstock), determined according to 98.74(c).
MW = Molecular weight of the gaseous feedstock (kg/kg-mole).
MVC = Molar volume conversion factor (849.5 scf per kg-mole at standard conditions).
44/12 = Ratio of molecular weights, CO2 to carbon.
0.001 = Conversion factor from kg to metric tons.
k = Processing unit.
n = Number of month.
(2) Liquid feedstock. You must calculate, from each ammonia manufacturing unit, the CO2 process emissions from liquid feedstock according to Equation G-2 of this section:

$ER30OC09.035$
Where:
CO2,L,k = Annual CO2 emissions arising from liquid feedstock consumption (metric tons).
Fdstkn = Volume of the liquid feedstock used in month n (gallons of feedstock).
CCn = Carbon content of the liquid feedstock, for month n (kg C per gallon of feedstock) determined according to 98.74(c).
44/12 = Ratio of molecular weights, CO2 to carbon.
0.001 = Conversion factor from kg to metric tons.
k = Processing unit.
n = Number of month.
(3) Solid feedstock. You must calculate, from each ammonia manufacturing unit, the CO2 process emissions from solid feedstock according to Equation G-3 of this section:

$ER30OC09.036$
Where:
CO2,S,k = Annual CO2 emissions arising from solid feedstock consumption (metric tons).
Fdstkn = Mass of the solid feedstock used in month n (kg of feedstock).
CCn = Carbon content of the solid feedstock, for month n (kg C per kg of feedstock), determined according to 98.74(c).
44/12 = Ratio of molecular weights, CO2 to carbon.
0.001 = Conversion factor from kg to metric tons.
k = Processing unit.
n = Number of month.
(4) You must calculate the annual process CO2 emissions from each ammonia processing unit k at your facility according to Equation G-4 of this section:

ER29NO13.027
Where:
ECO2
k = Annual CO2 emissions from each ammonia processing unit k (metric tons).
k = Processing unit.
(5) You must determine the combined CO2 emissions from all ammonia processing units at your facility using Equation G-5 of this section.

$ER30OC09.038$
Where:
CO2 = Annual combined CO2 emissions from all ammonia processing units (metric tons) (CO2 process emissions reported under this subpart may include CO2 that is later consumed on site for urea production, and therefore is not released to the ambient air from the ammonia manufacturing process unit(s)).
ECO2
k = Annual CO2 emissions from each ammonia processing unit (metric tons).
k = Processing unit.
n = Total number of ammonia processing units.
(c) If GHG emissions from an ammonia manufacturing unit are vented through the same stack as any combustion unit or process equipment that reports CO2 emissions using a CEMS that complies with the Tier 4 Calculation Methodology in subpart C of this part (General Stationary Fuel Combustion Sources), then the calculation methodology in paragraph (b) of this section shall not be used to calculate process emissions. The owner or operator shall report under this subpart the combined stack emissions according to the Tier 4 Calculation Methodology in § 98.33(a)(4) and all associated requirements for Tier 4 in subpart C of this part.

[74 FR 56374, Oct. 30, 2009, as amended at 75 FR 79156, Dec. 17, 2010]