Subpart C IVT Equation Inputs Summary
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This page lists the variables used in each Inputs Verifier Tool (IVT) equation in subpart C. This information is intended primarily for XML uploaders to enable them to understand how each IVT equation is calculated and to identify sources for the constants, default values, and lookup values needed to solve the equations.

Click the links for the equations below to view the variables used in the IVT calculations:

Equation C-1: Annual CO2 Mass Emissions for the Specific Fuel Type for Tier 1

Equation C-1 calculates annual CO2 mass emissions for the specific fuel type for Tier 1

 

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions for the specific fuel type

metric tons

 Output

Fuel

Mass or volume of fuel combusted per year, from company records as defined in §98.6

short tons for solid fuel

volume in standard cubic feet for gaseous fuel

volume in gallons for liquid fuel

 User input

HHV

Default high heat value of the fuel, from Table C-1 of this subpart

mmBtu per mass or mmBtu per volume, as applicable

Table C-1

EF

Fuel-specific default CO2 emission factor, from Table C-1 of this subpart

kg CO2/mmBtu

Table C-1

1 × 10−3

Conversion factor from kilograms to metric tons

 0.001

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Equation C-1a: Annual CO2 Mass Emissions from Natural Gas Combustion for Tier 1 - Therms

Equation C-1a calculates annual CO2 mass emissions from natural gas combustion when natural gas consumption in billing records is expressed in therms.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions from natural gas combustion

metric tons

 Output

Gas

Annual natural gas usage, from billing records

therms

 User input

EF

Fuel-specific default CO2 emission factor for natural gas, from Table C-1 of this subpart

kg CO2/mmBtu

 Table C-1

0.1

Conversion factor from therms to mmBtu

mmBtu/therm

 0.1

1 × 10−3

Conversion factor from kilograms to metric tons

-

 0.001

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Equation C-1b: Annual CO2 Mass Emissions from Natural Gas Combustion for Tier 1 - mmBtu

Equation C-1b calculates annual CO2 mass emissions from natural gas combustion when natural gas consumption in billing records is expressed in mmBtu.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions from natural gas combustion

metric tons

 Output

Gas

Annual natural gas usage, from billing records

mmBtu

 User input

EF

Fuel-specific default CO2 emission factor for natural gas, from Table C-1 of this subpart

kg CO2/mmBtu

 Table C-1

1 × 10−3

Conversion factor from kilograms to metric tons

-

 0.001

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Equation C-2a: Annual CO2 mass emissions for a specific fuel type for Tier 2

Equation C-2a calculates annual CO2 mass emissions for a specific fuel type for Tier 2.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions for a specific fuel type

metric tons

Output

Fuel

Mass or volume of the fuel combusted during the year, from company records as defined in §98.6

short tons for solid fuel

volume in standard cubic feet for gaseous fuel

volume in gallons for liquid fuel

User input

HHV

Annual average high heat value of the fuel

mmBtu per mass or volume. The average HHV shall be calculated according to the requirements of paragraph (a)(2)(ii) of this section

User input

EF

Fuel-specific default CO2 emission factor, from Table C-1 of this subpart

kg CO2/mmBtu

Table C-1 

1 × 10−3

Conversion factor from kilograms to metric tons

 -

0.001

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Equation C-2b: Weighted Annual Average High Heat Value of the Fuel

Equation C-2b calculates the weighted annual average high heat value of the fuel.

The table below defines the parameters in this equation. Equation C-2b does not include constants, default values, or lookup values.

Parameter  

Description

Units of Measure

Value or Source

(HHV)annual

Weighted annual average high heat value of the fuel

mmBtu per mass or volume

Output

(HHV)I

Measured high heat value of the fuel, for month “i” (which may be the arithmetic average of multiple determinations), or, if applicable, an appropriate substitute data value

mmBtu per mass or volume

User input 

(Fuel)I

Mass or volume of the fuel combusted during month “i,” from company records

short tons for solid fuel

volume in standard cubic feet for gaseous fuel

volume in gallons for liquid fuel

User input 

n

Number of months in the year that the fuel is burned in the unit

-

1-12 

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Equation C-2c: Annual CO2 Mass Emissions from MSW or Solid Fuel Combustion

Equation C-2c calculates annual CO2 mass emissions from MSW or solid fuel combustion.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions from MSW or solid fuel combustion

metric tons

Output

Steam

Total mass of steam generated by MSW or solid fuel combustion during the reporting year

lb steam

User input 

B

Ratio of the boiler's maximum rated heat input capacity to its design rated steam output capacity

mmBtu/lb steam

User input  

EF

Fuel-specific default CO2 emission factor, from Table C-1 of this subpart

kg CO2/mmBtu

Table C-1 

1 × 10−3

Conversion factor from kilograms to metric tons

-

 0.001

 

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Equation C-3: Annual CO2 Mass Emissions from the Combustion of the Specific Solid Fuel for Tier 3

Equation C-3 calculates annual CO2 mass emissions from the combustion of the specific solid fuel.

 

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions from the combustion of the specific solid fuel

metric tons

Output

Fuel

Annual mass of the solid fuel combusted, from company records as defined in §98.6

short tons

User input 

CC

Annual average carbon content of the solid fuel

percent by weight, expressed as a decimal fraction, e.g., 95% = 0.95

User input 

 

44/12

Ratio of molecular weights, CO2 to carbon

 44/12

0.91

Conversion factor from short tons to metric tons

 0.91

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Equation C-4: Annual CO2 Mass Emissions from the Combustion of the Specific Liquid Fuel for Tier 3

Equation C-4 calculates annual CO2 mass emissions from the combustion of the specific liquid fuel.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions from the combustion of the specific liquid fuel

metric tons

Output

Fuel

Annual volume of the liquid fuel combusted

gallons

User input 

CC

Annual average carbon content of the liquid fuel

kg C per gallon of fuel

User input 

44/12

Ratio of molecular weights, CO2 to carbon

44/12 

0.001

Conversion factor from kg to metric tons

0.001 

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Equation C-5: Annual CO2 Mass Emissions from the Combustion of the Specific Gaseous Fuel for Tier 3

Equation C-5 calculates annual CO2 mass emissions from combustion of the specific gaseous fuel.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CO2

Annual CO2 mass emissions from combustion of the specific gaseous fuel

metric tons

Output 

Fuel

Annual volume of the gaseous fuel combusted

scf

User input

CC

Annual average carbon content of the gaseous fuel

kg C per kg of fuel

User input

MW

Annual average molecular weight of the gaseous fuel

kg/kg-mole

User input

MVC

Molar volume conversion factor at standard conditions, as defined in §98.6

scf per kg mole

849.5 @ 68°F, or 836.6 @ 60 °F

44/12

Ratio of molecular weights, CO2 to carbon

44/12 

0.001

Conversion factor from kg to metric tons

0.001 

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Equation C-8: Annual CH4 or N2O Emissions from the Combustion of a Particular Type of Fuel for which Tier 1 or Tier 3 Is Used to Calculate CO2 Emissions

Equation C-8 calculates annual CH4 or N2O emissions from the combustion of a particular type of fuel for which Tier 1 or Tier 3 Is Used to Calculate CO2 Emissions

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CH4 or N2O

Annual CH4 or N2O emissions from the combustion of a particular type of fuel

metric tons

Output 

Fuel

Mass or volume of the fuel combusted, either from company records or directly measured by a fuel flow meter, as applicable

mass or volume per year

User Input

HHV

Default high heat value of the fuel from Table C-1 of this subpart; alternatively, for Tier 3, if actual HHV data are available for the reporting year, you may average these data using the procedures specified in paragraph (a)(2)(ii) of this section, and use the average value in Equation C-8

mmBtu per mass or volume

Table C-1 or calculated per §98.33(a)(2)(ii)

EF

Fuel-specific default emission factor for CH4 or N2O, from Table C-2 of this subpart

kg CH4 or N2O per mmBtu

Table C-2 

1 × 10−3

Conversion factor from kilograms to metric tons

-

 0.001

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Equation C-8a: Annual CH4 or N2O Emissions from the Combustion of Natural Gas - Therms

Equation C-8a calculates the annual CH4 or N2O emissions from the combustion of natural gas when natural gas consumption in billing records is expressed in therms.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CH4 or N2O

Annual CH4 or N2O emissions from the combustion of natural gas

metric tons

Output 

Fuel

Annual natural gas usage, from gas billing records

therms

User input

EF

Fuel-specific default emission factor for CH4 or N2O, from Table C-2 of this subpart

kg CH4 or N2O per mmBtu

Table C-2 

0.1

Conversion factor from therms to mmBtu

-

 0.1

1 × 10−3

Conversion factor from kilograms to metric tons

-

 0.001

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Equation C-8b: Annual CH4 or N2O Emissions from the Combustion of Natural Gas - mmBtu

Equation C-8b calculates the annual CH4 or N2O emissions from the combustion of natural gas when natural gas consumption in billing records is expressed in mmBtu.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values. 

Parameter

Description

Units of Measure

Value or Source

CH4 or N2O

Annual CH4 or N2O emissions from the combustion of natural gas

metric tons

Output 

Fuel

Annual natural gas usage, from gas billing records

mmBtu

User input

EF

Fuel-specific default emission factor for CH4 or N2O, from Table C-2 of this subpart

kg CH4 or N2O per mmBtu

Table C-2 

1 × 10−3

Conversion factor from kilograms to metric tons

-

 0.001

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Equation C-9a: Annual CH4 or N2O Emissions from the Combustion of a Particular Type of Fuel for which Tier 2 Is Used to Calculate CO2 Emissions

Equation C-9a calculates annual CH4 or N2O emissions from the combustion of a particular type of fuel for which Tier 2 is used to calculate CO2 emissions.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CH4 or N2O

Annual CH4 or N2O emissions from the combustion of a particular type of fuel

metric tons

Output 

Fuel

Mass or volume of the fuel combusted during the reporting year

short tons for solid fuel

volume in standard cubic feet for gaseous fuel

volume in gallons for liquid fuel 

User input 

HHV

High heat value of the fuel, averaged for all valid measurements for the reporting year

mmBtu per mass or volume

User input  

EF

Fuel-specific default emission factor for CH4 or N2O, from Table C-2 of this subpart

kg CH4 or N2O per mmBtu

Table C-2  

1 × 10−3

Conversion factor from kilograms to metric tons

-

0.001 

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Equation C-9b: Annual CH4 or N2O emissions from the combustion of a solid fuel for which Equation C-2b Is Used to Calculate CO2 Emissions

Equation C-9b calculates annual CH4 or N2O emissions from the combustion of a solid fuel for which Equation C-2b Is Used to Calculate CO2 Emissions.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CH4 or N2O

Annual CH4 or N2O emissions from the combustion of a solid fuel

metric tons

Output 

Steam

Total mass of steam generated by solid fuel combustion during the reporting year

lb steam

User input 

B

Ratio of the boiler's maximum rated heat input capacity to its design rated steam output

mmBtu/lb steam

User input 

EF

Fuel-specific emission factor for CH4 or N2O, from Table C-2 of this subpart

kg CH4 or N2O per mmBtu

Table C-2  

1 × 10−3

Conversion factor from kilograms to metric tons

-

0.001 

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Equation C-10: Annual CH4 or N2O Emissions from the Combustion of a Particular Type of Fuel for which Tier 4 Is Used to Calculate CO2 Emissions

Equation C-10 calculates annual CH4 or N2O emissions from the combustion of a particular type of fuel for which Tier 4 is used to calculate CO2 emissions.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

CH4 or N2O

Annual CH4 or N2O emissions from the combustion of a particular type of fuel

metric tons

 

(HI)A

Cumulative annual heat input from combustion of the fuel

mmBtu

 

EF

Fuel-specific emission factor for CH4 or N2O, from Table C-2 of this section

kg CH4 or N2O per mmBtu)

 

0.001

Conversion factor from kg to metric tons

-

 

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Equation C-13: Annual Volume of CO2 Emitted from Combustion of a Particular Fossil Fuel

Equation C-13 calculates annual volume of CO2 emitted from combustion of a particular fossil fuel.

The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.

Parameter

Description

Units of Measure

Value or Source

Vff

Annual volume of CO2 emitted from combustion of a particular fossil fuel

scf

Output 

Fuel

Total quantity of the fossil fuel combusted in the reporting year, from company records, as defined in §98.6

lb for solid fuel

gallons for liquid fuel

scf for gaseous fuel

User input

Fc

Fuel-specific carbon based F-factor, either a default value from Table 1 in section 3.3.5 of appendix F to 40 CFR part 75, or a site-specific value determined under section 3.3.6 of appendix F to 40 CFR part 75

scf CO2/mmBtu

Table 1 in Appendix F in 40 CFR 75

or

Section 3.3.6 of Appendix F to 40 CFR 75

HHV

Annual average high heat value of the fossil fuel, from fuel sampling and analysis (Sampled as specified (e.g., monthly, quarterly, semi-annually, or by lot in §98.34(a)(2). The average HHV shall be calculated according to the requirements of paragraph (a)(2)(ii) of this section.)

Btu/lb for solid fuel

Btu/gal for liquid fuel

Btu/scf for gaseous fuel

User input

 

106

Conversion factor, Btu per mmBtu

-

 1000000

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