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Subpart G—Ammonia Manufacturing

§98.70 Definition of source category.

The ammonia manufacturing source category comprises the process units listed in 

paragraphs (a) and (b) of this section.

(a) Ammonia manufacturing processes in which ammonia is manufactured from a fossilbased feedstock produced via steam reforming of a hydrocarbon.

(b) Ammonia manufacturing processes in which ammonia is manufactured through the 

gasification of solid and liquid raw material.

§98.71 Reporting threshold.

You must report GHG emissions under this subpart if your facility contains an ammonia 

manufacturing process and the facility meets the requirements of either §98.2(a)(1) or (2).

§98.72 GHGs to report.

You must report:

(a) CO2 process emissions from steam reforming of a hydrocarbon or the gasification of 

solid and liquid raw material, reported for each ammonia manufacturing process unit following 

the requirements of this subpart (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).

(b) CO2, CH4, and N2O emissions from each stationary fuel combustion unit. You must 

report these emissions under subpart C of this part (General Stationary Fuel Combustion 

Sources), by following the requirements of subpart C, except that for ammonia manufacturing 

processes subpart C does not apply to any CO2 resulting from combustion of the waste recycle 

stream (commonly referred to as the purge gas stream).
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(c) CO2 emissions collected and transferred off site under subpart PP of this part 

(Suppliers of CO2), following the requirements of subpart PP.

§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:

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).
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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:

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:

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).
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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:

Where:

ECO2k = 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.

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)).

ECO2k = Annual CO2 emissions from each ammonia processing unit (metric tons).

k = Processing unit.

n = Total number of ammonia processing units.
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(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.

§98.74 Monitoring and QA/QC requirements.

(a) You must continuously measure the quantity of gaseous or liquid feedstock consumed 

using a flow meter. The quantity of solid feedstock consumed can be obtained from company

records and aggregated on a monthly basis.

(b) You must document the procedures used to ensure the accuracy of the estimates of 

feedstock consumption.

(c) You must determine monthly carbon contents and the average molecular weight of 

each feedstock consumed from reports from your supplier. As an alternative to using supplier 

information on carbon contents, you can also collect a sample of each feedstock on a monthly

basis and analyze the carbon content and molecular weight of the fuel using any of the following 

methods listed in paragraphs (c)(1) through (c)(8) of this section, as applicable.

(1) ASTM D1945-03 Standard Test Method for Analysis of Natural Gas by Gas 

Chromatography (incorporated by reference, see §98.7).

(2) ASTM D1946-90 (Reapproved 2006) Standard Practice for Analysis of Reformed 

Gas by Gas Chromatography (incorporated by reference, see §98.7).
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(3) ASTM D2502-04 (Reapproved 2002) Standard Test Method for Estimation of Mean 

Relative Molecular Mass of Petroleum Oils from Viscosity Measurements (incorporated by

reference, see §98.7).

(4) ASTM D2503-92 (Reapproved 2007) Standard Test Method for Relative Molecular 

Mass (Molecular Weight) of Hydrocarbons by Thermoelectric Measurement of Vapor Pressure 

(incorporated by reference, see §98.7).

(5) ASTM D3238-95 (Reapproved 2005) Standard Test Method for Calculation of 

Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method 

(incorporated by reference, see §98.7).

(6) ASTM D5291-02 (Reapproved 2007) Standard Test Methods for Instrumental 

Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants 

(incorporated by reference, see §98.7).

(7) ASTM D3176-89 (Reapproved 2002) Standard Practice for Ultimate Analysis of Coal 

and Coke (incorporated by reference, see §98.7).

(8) ASTM D5373-08 Standard Methods for Instrumental Determination of Carbon, 

Hydrogen, and Nitrogen in Laboratory Samples of Coal (incorporated by reference, see §98.7).

(d) Calibrate all oil and gas flow meters that are used to measure liquid and gaseous 

feedstock volumes and flow rates (except for gas billing meters) according to the monitoring and 

QA/QC requirements for the Tier 3 methodology in §98.34(b)(1). Perform oil tank drop 

measurements (if used to quantify feedstock volumes) according to §98.34(b)(2).

(e) For quality assurance and quality control of the supplier data, on an annual basis, you 

must measure the carbon contents of a representative sample of the feedstocks consumed using 

the appropriate ASTM Method as listed in paragraphs (c)(1) through (c)(8) of this section.
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(f) You may use company records or an engineering estimate to determine the annual 

ammonia production and the annual methanol production.

(g) If CO2 from ammonia production is used to produce urea at the same facility, you 

must determine the quantity of urea produced using methods or plant instruments used for 

accounting purposes (such as sales records). You must document the procedures used to ensure 

the accuracy of the estimates of urea produced.

§98.75 Procedures for estimating missing data.

A complete record of all measured parameters used in the GHG emissions calculations is 

required. Therefore, whenever the monitoring and quality assurance procedures in §98.74 cannot 

be followed (e.g., if a meter malfunctions during unit operation), a substitute data value for the 

missing parameter shall be used in the calculations following paragraphs (a) and (b) of this 

section. You must document and keep records of the procedures used for all such estimates.

(a) For missing data on monthly carbon contents of feedstock, the substitute data value 

shall be the arithmetic average of the quality-assured values of that carbon content in the month 

preceding and the month immediately following the missing data incident. If no quality-assured 

data are available prior to the missing data incident, the substitute data value shall be the first 

quality-assured value for carbon content obtained in the month after the missing data period.

(b) For missing feedstock supply rates used to determine monthly feedstock consumption, 

you must determine the best available estimate(s) of the parameter(s), based on all available 

process data.

§ 98.76 Data reporting requirements.
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In addition to the information required by § 98.3(c), each annual report must contain the 

information specified in paragraphs (a) and (b) of this section, as applicable for each ammonia 

manufacturing process unit.

(a) If a CEMS is used to measure CO2 emissions, then you must report the relevant 

information required under § 98.36 for the Tier 4 Calculation Methodology and the information 

in paragraphs (a)(1) through (3) of this section:

(1) Annual quantity of each type of feedstock consumed for ammonia manufacturing (scf 

of feedstock or gallons of feedstock or kg of feedstock).

(2) Method used for determining quantity of feedstock used.

(3) Annual ammonia production (metric tons, sum of all process units reported within 

subpart G).

(b) If a CEMS is not used to measure emissions, then you must report all of the following 

information in this paragraph (b):

(1) Annual CO2 process emissions (metric tons) for each ammonia manufacturing process 

unit.

(2) Annual quantity of each type of feedstock consumed for ammonia manufacturing (scf 

of feedstock or gallons of feedstock or kg of feedstock).

(3) Method used for determining quantity of monthly feedstock used.

(4) Whether carbon content for each feedstock for month n is based on reports from the 

supplier or analysis of carbon content.

(5) If carbon content of feedstock for month n is based on analysis, the test method used.

(6) Sampling analysis results of carbon content of feedstock as determined for QA/QC of 

supplier data under § 98.74(e).
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(7) Annual average carbon content of each type of feedstock consumed.

(8) Reserved.

(9) Reserved.

(10) Reserved.

(11) Reserved.

(12) Annual urea production (metric tons) and method used to determine urea production.

(13) Annual CO2 emissions (metric tons) from the steam reforming of a hydrocarbon or 

the gasification of solid and liquid raw material at the ammonia manufacturing process unit used 

to produce urea and the method used to determine the CO2 consumed in urea production.

(14) Annual ammonia production (metric tons, sum of all process units reported within 

subpart G).

(15) Annual methanol production for each process unit (metric tons), regardless of 

whether the methanol is subsequently destroyed, vented, or sold as product.

§ 98.77 Records that must be retained.

In addition to the records required by § 98.3(g), you must retain the following records 

specified in paragraphs (a) through (c) of this section for each ammonia manufacturing unit.

(a) If a CEMS is used to measure emissions, retain records of all feedstock purchases in 

addition to the requirements in § 98.37 for the Tier 4 Calculation Methodology.

(b) If a CEMS is not used to measure process CO2 emissions, you must also retain the 

records specified in paragraphs (b)(1) through (b)(2) of this section:

(1) Records of all analyses and calculations conducted for reported data as listed in § 

98.76(b).
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(2) Monthly records of carbon content of feedstock from supplier and/or all analyses 

conducted of carbon content.

(c) Verification software records. You must keep a record of the file generated by the 

verification software specified in § 98.5(b) for the applicable data specified in paragraphs (c)(1) 

through (7) of this section. Retention of this file satisfies the recordkeeping requirement for the 

data in paragraphs (c)(1) through (7) of this section.

(1) Volume of each gaseous feedstock used in month (scf of feedstock) (in Equation G-1

of § 98.73).

(2) Carbon content of each gaseous feedstock, for month (kg C per kg of feedstock) (in 

Equation G-1).

(3) Molecular weight of each gaseous feedstock per ammonia manufacturing unit with 

gaseous feedstock (kg/kg-mole) (Equation G-1).

(4) Volume of each liquid feedstock used in month (gallons of feedstock) (Equation G-2

of § 98.73).

(5) Carbon content of each liquid feedstock, for month (kg C per gallon of feedstock) 

(Equation G-2).

(6) Mass of each solid feedstock used in month (kg of feedstock) (Equation G-3 of § 

98.73).

(7) Carbon content of each solid feedstock, for month (kg C per kg of feedstock) 

(Equation G-3).

§98.78 Definitions.

All terms used in this subpart have the same meaning given in the Clean Air Act and subpart A 

of this part.