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 fossil-based 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) CO2process 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 (CO2process emissions 

reported under this subpart may include CO2that 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 

CO2resulting from combustion of the waste recycle stream 

(commonly referred to as the purge gas stream).

(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 

CO2emissions 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 

CO2emissions 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 CO2process emissions from gaseous 

feedstock according to Equation G–1 of this section:

Where:

CO2,G,k= Annual CO2emissions 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, CO2to 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 CO2process emissions from liquid 

feedstock according to Equation G–2 of this section:

Where:

CO2,L,k= Annual CO2emissions 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, CO2to 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 CO2process 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).

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, CO2to 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:

ECO2,k  CO2,G,k  CO2,L,k  CO2,S ,k (Eq. G-4)

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.





j

k

CO ECO k

1

2 2, (Eq. G-5)

Where:

CO2 = Annual combined CO2emissions 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 k 

(metric tons).

k = Processing unit.

j = 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 CO2emissions 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).

(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.

(f)[Reserved]

(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.

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) and (a)(2) 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.

(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 CO2process emissions (metric tons) for each 

ammonia manufacturing process unit.

(2) Monthly quantity of each type of feedstock consumed for 

ammonia manufacturing for each ammonia processing unit (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).

(7) If a facility uses gaseous feedstock, the carbon 

content of the gaseous feedstock, for month n, (kg C per kg of 

feedstock).

(8) If a facility uses gaseous feedstock, the molecular 

weight of the gaseous feedstock (kg/kg-mole).

(9) If a facility uses gaseous feedstock, the molar volume 

conversion factor of the gaseous feedstock (scf per kg-mole).

(10) If a facility uses liquid feedstock, the carbon 

content of the liquid feedstock, for month n, (kg C per gallon 

of feedstock).

(11) If a facility uses solid feedstock, the carbon content 

of the solid feedstock, for month n, (kg C per kg of feedstock).
(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.

§ 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) and (b) 

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 CO2emissions, 

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).
(2) Monthly records of carbon content of feedstock from 

supplier and/or all analyses conducted of carbon content.

§ 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.