# 98.273 Calculating GHG emissions.
(a) For each chemical recovery furnace located at a kraft or soda facility, you must determine CO<sub>2</sub>, biogenic CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O emissions using the procedures in paragraphs (a)(1) through (4) of this section. CH4 and N2O emissions must be calculated as the sum of emissions from combustion of fuels and combustion of biomass in spent liquor solids.
(1) Calculate CO<sub>2</sub> emissions from fuel combustion using direct measurement of fuels consumed and default emissions factors according to the Tier 1 methodology for stationary combustion sources in § 98.33(a)(1). Tiers 2 or 3 from § 98.33(a)(2) or (3) may be used to calculate CO<sub>2</sub> emissions if the respective monitoring and QA/QC requirements described in § 98.34 are met.
(2) Calculate CH<sub>4</sub> and N<sub>2</sub>O emissions from fuel combustion using direct measurement of fuels consumed, default or site-specific HHV, and default emissions factors and convert to metric tons of CO<sub>2</sub> equivalent according to the methodology for stationary combustion sources in § 98.33(c).
(3) Calculate biogenic CO<sub>2</sub> emissions and emissions of CH<sub>4</sub> and N<sub>2</sub>O from biomass using measured quantities of spent liquor solids fired, site-specific HHV, and default emissions factors, according to equation AA-1 to this section:
Where:
CO<sub>2</sub>, CH<sub>4</sub>, or N<sub>2</sub>O, from Biomass = Biogenic CO<sub>2</sub> emissions or emissions of CH<sub>4</sub> or N<sub>2</sub>O from spent liquor solids combustion (metric tons per year).
Solids = Mass of spent liquor solids combusted (short tons per year) determined according to § 98.274(b).
HHV = Annual high heat value of the spent liquor solids (mmBtu per kilogram) determined according to § 98.274(b).
EF = Default emission factor for CO<sub>2</sub>, CH<sub>4</sub>, or N<sub>2</sub>O, from table AA-1 to this subpart (kg CO<sub>2</sub>, CH<sub>4</sub>, or N<sub>2</sub>O per mmBtu).
0.90718 = Conversion factor from short tons to metric tons.
(4) Calculate biogenic CO<sub>2</sub> emissions from combustion of biomass (other than spent liquor solids) with other fuels according to the applicable methodology for stationary combustion sources in § 98.33(e).
(b) For each chemical recovery combustion unit located at a sulfite or stand-alone semichemical facility, you must determine CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O emissions using the procedures in paragraphs (b)(1) through (5) of this section:
(1) Calculate CO<sub>2</sub> emissions from fuel combustion using direct measurement of fuels consumed and default emissions factors according to the Tier 1 Calculation Methodology for stationary combustion sources in § 98.33(a)(1). Tiers 2 or 3 from § 98.33(a)(2) or (3) may be used to calculate CO<sub>2</sub> emissions if the respective monitoring and QA/QC requirements described in § 98.34 are met.
(2) Calculate CH<sub>4</sub> and N<sub>2</sub>O emissions from fuel combustion using direct measurement of fuels consumed, default or site-specific HHV, and default emissions factors and convert to metric tons of CO<sub>2</sub> equivalent according to the methodology for stationary combustion sources in § 98.33(c).
(3) Calculate biogenic CO<sub>2</sub> emissions using measured quantities of spent liquor solids fired and the carbon content of the spent liquor solids, according to equation AA-2 to this section:
Where:
Biogenic CO<sub>2</sub> = Annual CO<sub>2</sub> mass emissions for spent liquor solids combustion (metric tons per year).
Solids = Mass of the spent liquor solids combusted (short tons per year) determined according to § 98.274(b).
CC = Annual carbon content of the spent liquor solids, determined according to § 98.274(b) (percent by weight, expressed as a decimal fraction, *e.g.* , 95% = 0.95).
44/12 = Ratio of molecular weights, CO<sub>2</sub> to carbon.
0.90718 = Conversion from short tons to metric tons.
(4) Calculate biogenic CO<sub>2</sub> emissions from combustion of biomass (other than spent liquor solids) with other fuels according to the applicable methodology for stationary combustion sources in § 98.33(e).
(c) For each pulp mill lime kiln located at a kraft or soda facility, you must determine CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O emissions using the procedures in paragraphs (c)(1) through (4) of this section:
(1) Calculate CO<sub>2</sub> emissions from fuel combustion using direct measurement of fuels consumed and default HHV and default emissions factors, according to the Tier 1 Calculation Methodology for stationary combustion sources in § 98.33(a)(1). Tiers 2 or 3 from § 98.33(a)(2) or (3) may be used to calculate CO<sub>2</sub> emissions if the respective monitoring and QA/QC requirements described in § 98.34 are met.
(2) Calculate CH<sub>4</sub> and N<sub>2</sub>O emissions from fuel combustion using direct measurement of fuels consumed, default or site-specific HHV, and default emissions factors and convert to metric tons of CO<sub>2</sub> equivalent according to the methodology for stationary combustion sources in § 98.33(c); use the default HHV listed in table C-1 to subpart C of this part and the default CH<sub>4</sub> and N<sub>2</sub>O emissions factors listed in table AA-2 to this subpart.
(3) Biogenic CO<sub>2</sub> emissions from conversion of CaCO<sub>3</sub> to CaO are included in the biogenic CO<sub>2</sub> estimates calculated for the chemical recovery furnace in paragraph (a)(3) of this section.
(4) Calculate biogenic CO<sub>2</sub> emissions from combustion of biomass with other fuels according to the applicable methodology for stationary combustion sources in § 98.33(e).
(d) For makeup chemical use, you must calculate CO<sub>2</sub> emissions by using direct or indirect measurement of the quantity of chemicals added and ratios of the molecular weights of CO<sub>2</sub> and the makeup chemicals, according to equation AA-3 to this section:
Where:
CO<sub>2</sub> = CO<sub>2</sub> mass emissions from makeup chemicals (kilograms/yr).
M (CaCO<sub>3</sub>) = Make-up quantity of CaCO<sub>3</sub> used for the reporting year (metric tons per year).
M (NaCO<sub>3</sub>) = Make-up quantity of Na<sub>2</sub>CO<sub>3</sub> used for the reporting year (metric tons per year).
44 = Molecular weight of CO<sub>2</sub>.
100 = Molecular weight of CaCO<sub>3</sub>.
105.99 = Molecular weight of Na<sub>2</sub>CO<sub>3</sub>.
[74 FR 56374, Oct. 30, 2009, as amended at 75 FR 79166, Dec. 17, 2010; 78 FR 71965, Nov. 29, 2013; 81 FR 89264, Dec. 9, 2016; 89 FR 31931, Apr. 25, 2024]