Calculating GHG emissions.

  1. Law
  2. CFR 40
  3. Protection of Environment
  4. Environmental Protection Agency
  5. Air Programs
  6. Mandatory Greenhouse Gas Reporting
  7. Suppliers of Natural Gas and Natural Gas Liquids
  8. Calculating GHG emissions.

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§ 98.403 Calculating GHG emissions.

(a) LDCs and fractionators shall, for each individual product reported under this part, calculate the estimated CO2 emissions that would result from the complete combustion or oxidation of the products supplied using either of Calculation Methodology 1 or 2 of this subpart:

(1) Calculation Methodology 1. NGL fractionators shall estimate CO2 emissions that would result from the complete combustion or oxidation of the product(s) supplied using Equation NN-1 of this section. The annual volume of each NGL product supplied (Fuelh) shall include any amount of that NGL supplied in a mixture or blend of two or more products listed in Tables NN-1 and NN-2 of this subpart. The annual volume of each NGL product supplied shall exclude any amount of that NGL contained in bulk NGLs exiting the facility (e.g., y-grade, o-grade, and other bulk NGLs). LDCs shall estimate CO2 emissions that would result from the complete combustion or oxidation of the natural gas received at the city gate (including natural gas that is transported by, but not owned by, the reporter) using Equation NN-1 of this section. For each product, use the default value for higher heating value and CO2 emission factor in Table NN-1 of this subpart. Alternatively, for each product, a reporter-specific higher heating value and CO2 emission factor may be used, in place of one or both defaults provided they are developed using methods outlined in § 98.404. For each product, you must use the same volume unit throughout the equation.

Where:

CO2i = Annual CO2 mass emissions that would result from the combustion or oxidation of each product “h” for redelivery to all recipients (metric tons).

Fuelh = Total annual volume of product “h” supplied (volume per year, in thousand standard cubic feet (Mscf) for natural gas and bbl for NGLs).

HHVh = Higher heating value of product “h” supplied (MMBtu/Mscf or MMBtu/bbl).

EFh = CO2 emission factor of product “h” (kg CO2/MMBtu).

1 × 10−3 = Conversion factor from kilograms to metric tons (MT/kg).

(2) Calculation Methodology 2. NGL fractionators shall estimate CO2 emissions that would result from the complete combustion or oxidation of the product(s) supplied using Equation NN-2 of this section. The annual volume of each NGL product supplied (Fuelh) shall include any amount of that NGL supplied in a mixture or blend of two or more products listed in Tables NN-1 and NN-2 of this subpart. The annual volume of each NGL product supplied shall exclude any amount of that NGL contained in bulk NGLs exiting the facility (e.g., y-grade, o-grade, and other bulk NGLs). LDCs shall estimate CO2 emissions that would result from the complete combustion or oxidation of the natural gas received at the city gate (including natural gas that is transported by, but not owned by, the reporter) using Equation NN-2 of this section. For each product, use the default CO2 emission factor found in Table NN-2 of this subpart. Alternatively, for each product, a reporter-specific CO2 emission factor may be used in place of the default factor, provided it is developed using methods outlined in § 98.404. For each product, you must use the same volume unit throughout the equation.

Where:

CO2i = Annual CO2 mass emissions that would result from the combustion or oxidation of each product “h” (metric tons)

Fuelh = Total annual volume of product “h” supplied (volume per year, in Mscf for natural gas and bbl for NGLs).

EFh = CO2 emission factor of product “h” (MT CO2/bbl, or MT CO2/Mscf)

(b) Each LDC shall follow the procedures below.

(1) For natural gas that is received for redelivery to downstream gas transmission pipelines and other local distribution companies, use Equation NN-3 of this section and the default values for the CO2 emission factors found in Table NN-2 of this subpart. Alternatively, reporter-specific CO2 emission factors may be used, provided they are developed using methods outlined in § 98.404.

Where:

CO2j = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas for redelivery to transmission pipelines or other LDCs (metric tons).

Fuel = Total annual volume of natural gas supplied to downstream gas transmission pipelines and other local distribution companies (Mscf per year).

EF = Fuel-specific CO2 emission factor (MT CO2/Mscf).

(2)

(i) For natural gas delivered to large end-users, use Equation NN-4 of this section and the default values for the CO2 emission factors found in Table NN-2 of this subpart. A large end-user means any end-user facility receiving greater than or equal to 460,000 Mscf of natural gas per year. If the LDC does not know the total quantity of gas delivered to the end-user facility based on readily available information in the LDCs possession, then large end-user means any single meter at an end-user facility to which the LDC delivers equal to or greater than 460,000 Mscf per year.

(ii) Alternatively, reporter-specific CO2 emission factors may be used, provided they are developed using methods outlined in § 98.404.

Where:

CO2k = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas delivered to each large end-user k, as defined in paragraph (b)(2)(i) of this section (metric tons).

Fuel = Total annual volume of natural gas supplied to each large end-user k, as defined in paragraph (b)(2)(i) of this section (Mscf per year).

EF = Fuel-specific CO2 emission factor (MT CO2/Mscf).

(3) For the net change in natural gas stored on system by the LDC during the reporting year, use Equation NN-5a of this section. For natural gas that is received by means other than through the city gate, and is not otherwise accounted for by Equation NN-1 or NN-2 of this section, use Equation NN-5b of this section.

(i) For natural gas received by the LDC that is injected into on-system storage, and/or liquefied and stored, and for gas removed from storage and used for deliveries, use Equation NN-5a of this section and the default value for the CO2 emission factors found in Table NN-2 of this subpart. Alternatively, a reporter-specific CO2 emission factor may be used, provided it is developed using methods outlined in § 98.404.

Where:

CO2l = Annual CO2 mass emissions that would result from the combustion or oxidation of the net change in natural gas stored on system by the LDC within the reporting year (metric tons).

Fuel1 = Total annual volume of natural gas added to storage on-system or liquefied and stored in the reporting year (Mscf per year).

Fuel2 = Total annual volume of natural gas that is removed from storage or vaporized and removed from storage and used for deliveries to customers or other LDCs by the LDC within the reporting year (Mscf per year).

EF = CO2 emission factor for natural gas placed into/removed from storage (MT CO2/Mscf).

(ii) For natural gas received by the LDC that bypassed the city gate, use Equation NN-5b of this section. This includes natural gas received directly by LDC systems from producers or natural gas processing plants from local production, received as a liquid and vaporized for delivery, or received from any other source that bypassed the city gate. Use the default value for the CO2 emission factors found in Table NN-2 of this subpart. Alternatively, a reporter-specific CO2 emission factor may be used, provided it is developed using methods outlined in § 98.404.

Where:

CO2n = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas received that bypassed the city gate and is not otherwise accounted for by Equation NN-1 or NN-2 of this section (metric tons).

Fuelz = Total annual volume of natural gas received that was not otherwise accounted for by Equation NN-1 or NN-2 of this section (natural gas from producers and natural gas processing plants from local production, or natural gas that was received as a liquid, vaporized and delivered, and any other source that bypassed the city gate). (Mscf per year)

EFz = Fuel-specific CO2 emission factor (MT CO2/Mscf)

(4) Calculate the total CO2 emissions that would result from the complete combustion or oxidation of the annual supply of natural gas to end-users that receive a supply less than 460,000 Mscf per year using Equation NN-6 of this section.

Where:

CO2 = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas delivered to LDC end-users not covered in paragraph (b)(2) of this section (metric tons).

CO2i = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas received at the city gate as calculated in paragraph (a)(1) or (2) of this section (metric tons).

CO2j = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas delivered to transmission pipelines or other LDCs as calculated in paragraph (b)(1) of this section (metric tons).

CO2k = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas delivered to each large end-user as calculated in paragraph (b)(2) of this section (metric tons).

CO2l = Annual CO2 mass emissions that would result from the combustion or oxidation of the net change in natural gas stored by the LDC within the reported year as calculated in paragraph (b)(3)(i) of this section (metric tons).

CO2n = Annual CO2 mass emissions that would result from the combustion or oxidation of natural gas that was received by the LDC directly from sources bypassing the city gate, and is not otherwise accounted for in Equation NN-1 or NN-2 of this section, as calculated in paragraph (b)(3)(ii) of this section (metric tons).

(c) Each NGL fractionator shall follow the following procedures.

(1)

(i) For fractionated NGLs received by the reporter from other NGL fractionators, you shall use Equation NN-7 of this section and the default values for the CO2 emission factors found in Table NN-2 of this subpart.

(ii) Alternatively, reporter-specific CO2 emission factors may be used, provided they are developed using methods outlined in § 98.404.

Where:

CO2m = Annual CO2 mass emissions that would result from the combustion or oxidation of each fractionated NGL product “g” received from other fractionators (metric tons).

Fuelg = Total annual volume of each NGL product “g” received from other fractionators (bbls).

EFg = Fuel-specific CO2 emission factor of NGL product “g” (MT CO2/bbl).

(2) Calculate the total CO2 equivalent emissions that would result from the combustion or oxidation of fractionated NGLs supplied less the quantity received from other fractionators using Equation NN-8 of this section.

Where:

CO2 = Annual CO2 mass emissions that would result from the combustion or oxidation of fractionated NGLs delivered to customers or on behalf of customers less the quantity received from other fractionators (metric tons).

CO2i = Annual CO2 mass emissions that would result from the combustion or oxidation of fractionated NGLs delivered to all customers or on behalf of customers as calculated in paragraph (a)(1) or (2) of this section (metric tons).

CO2m = Annual CO2 mass emissions that would result from the combustion or oxidation of fractionated NGLs received from other fractionators and calculated in paragraph (c)(1) of this section (metric tons).

[74 FR 56374, Oct. 30, 2009, as amended at 75 FR 66478, Oct. 28, 2010; 78 FR 71975, Nov. 29, 2013; 81 FR 89268, Dec. 9, 2016]


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