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Subpart DD—Electrical Transmission and Distribution Equipment Use

§ 98.300 Definition of the source category.

(a) The electrical transmission and distribution equipment use source category consists of 

all electric transmission and distribution equipment and servicing inventory insulated with or 

containing sulfur hexafluoride (SF6) or perfluorocarbons (PFCs) used within an electric power 

system. Electric transmission and distribution equipment and servicing inventory includes, but is 

not limited to:

(1) Gas-insulated substations.

(2) Circuit breakers.

(3) Switchgear, including closed-pressure and hermetically sealed-pressure switchgear 

and gas-insulated lines containing SF6 or PFCs.

(4) Gas containers such as pressurized cylinders.

(5) Gas carts.

(6) Electric power transformers.

(7) Other containers of SF6 or PFC.

§ 98.301 Reporting threshold.

(a) You must report GHG emissions from an electric power system if the total nameplate 

capacity of SF6 and PFC containing equipment (excluding hermetically sealed-pressure 

equipment) located within the facility, when added to the total nameplate capacity of SF6 and 

PFC containing equipment (excluding hermetically sealed-pressure equipment) that is not 

located within the facility but is under common ownership or control, exceeds 17,820 pounds 

and the facility meets the requirements of § 98.2(a)(1).
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(b) A facility other than an electric power system that is subject to this part because of 

emissions from any other source category listed in Table A-3 or A-4 in subpart A of this part is 

not required to report emissions under subpart DD of this part unless the total nameplate capacity

of SF6 and PFC containing equipment located within that facility exceeds 17,820 pounds.

§ 98.302 GHGs to report.

You must report total SF6 and PFC emissions from your facility (including emissions 

from fugitive equipment leaks, installation, servicing, equipment decommissioning and disposal, 

and from storage cylinders) resulting from the transmission and distribution servicing inventory

and equipment listed in § 98.300(a). For acquisitions of equipment containing or insulated with 

SF6 or PFCs, you must report emissions from the equipment after the title to the equipment is 

transferred to the electric power transmission or distribution entity.

§ 98.303 Calculating GHG emissions.

(a) Calculate the annual SF6 and PFC emissions using the mass-balance approach in 

Equation DD-1 of this section:

where:

Decrease in SF6 Inventory = (pounds of SF6 stored in containers, but not in energized 

equipment, at the beginning of the year) − (pounds of SF6 stored 

in containers, but not in energized equipment, at the end of the 

year).

Acquisitions of SF6 = (pounds of SF6 purchased from chemical producers or 

distributors in bulk) + (pounds of SF6 purchased from equipment 

manufacturers or distributors with or inside equipment, including 

hermetically sealed-pressure switchgear) + (pounds of SF6

returned to facility after off-site recycling).
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Disbursements of SF6 = (pounds of SF6 in bulk and contained in equipment that is sold to 

other entities) + (pounds of SF6 returned to suppliers) + (pounds 

of SF6 sent off site for recycling) + (pounds of SF6 sent off-site 

for destruction).

Net Increase in Total 

Nameplate Capacity 

of Equipment Operated = (The Nameplate Capacity of new equipment in pounds, including 

hermetically sealed-pressure switchgear) − (Nameplate Capacity 

of retiring equipment in pounds, including hermetically sealedpressure switchgear). (Note that Nameplate Capacity refers to the 

full and proper charge of equipment rather than to the actual 

charge, which may reflect leakage).

(b) Use Equation DD-1 of this section to estimate emissions of PFCs from power 

transformers, substituting the relevant PFC(s) for SF6 in the equation.

§ 98.304 Monitoring and QA/QC requirements.

(a) For calendar year 2011 monitoring, you may follow the provisions of § 98.3(d)(1) 

through (d)(2) for best available monitoring methods rather than follow the monitoring

requirements of this section. For purposes of this subpart, any reference in § 98.3(d)(1) through 

(d)(2) to 2010 means 2011, to March 31 means June 30, and to April 1 means July 1. Any 

reference to the effective date in § 98.3(d)(1) through (d)(2) means February 28, 2011.

(b) You must adhere to the following QA/QC methods for reviewing the completeness 

and accuracy of reporting:

(1) Review inputs to Equation DD-1 of this section to ensure inputs and outputs to the 

company's system are included.

(2) Do not enter negative inputs and confirm that negative emissions are not calculated. 

However, the Decrease in SF6 Inventory and the Net Increase in Total Nameplate Capacity may 

be calculated as negative numbers.

(3) Ensure that beginning-of-year inventory matches end-of-year inventory from the 

previous year.
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(4) Ensure that in addition to SF6 purchased from bulk gas distributors, SF6 purchased 

from Original Equipment Manufacturers (OEM) and SF6 returned to the facility from off-site 

recycling are also accounted for among the total additions.

(c) Ensure the following QA/QC methods are employed throughout the year:

(1) Ensure that cylinders returned to the gas supplier are consistently weighed on a scale 

that is certified to be accurate and precise to within 2 pounds of true weight and is periodically 

recalibrated per the manufacturer's specifications. Either measure residual gas (the amount of gas 

remaining in returned cylinders) or have the gas supplier measure it. If the gas supplier weighs 

the residual gas, obtain from the gas supplier a detailed monthly accounting, within ± 2 pounds, 

of residual gas amounts in the cylinders returned to the gas supplier.

(2) Ensure that cylinders weighed for the beginning and end of year inventory

measurements are weighed on a scale that is certified to be accurate and precise to within 2 

pounds of true weight and is periodically recalibrated per the manufacturer's specifications. All 

scales used to measure quantities that are to be reported under § 98.306 must be calibrated using 

calibration procedures specified by the scale manufacturer. Calibration must be performed prior 

to the first reporting year. After the initial calibration, recalibration must be performed at the 

minimum frequency specified by the manufacturer.

(3) Ensure all substations have provided information to the manager compiling the 

emissions report (if it is not already handled through an electronic inventory system).

(d) GHG Monitoring Plans, as described in § 98.3(g)(5), must be completed by April 1, 

2011.

§ 98.305 Procedures for estimating missing data.
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A complete record of all measured parameters used in the GHG emissions calculations is 

required. Replace missing data, if needed, based on data from equipment with a similar 

nameplate capacity for SF6 and PFC, and from similar equipment repair, replacement, and 

maintenance operations.

§ 98.306 Data reporting requirements.

In addition to the information required by § 98.3(c), each annual report must contain the 

following information for each electric power system, by chemical:

(a) Nameplate capacity of equipment (pounds) containing SF6 and nameplate capacity of 

equipment (pounds) containing each PFC:

(1) Existing at the beginning of the year (excluding hermetically sealed-pressure 

switchgear).

(2) New hermetically sealed-pressure switchgear during the year.

(3) New SF6- or PFC-insulated equipment other than hermetically sealed-pressure 

switchgear during the year.

(4) Retired hermetically sealed-pressure switchgear during the year.

(5) Retired SF6- or PFC-insulated equipment other than hermetically sealed-pressure 

switchgear during the year.

(b) Transmission miles (length of lines carrying voltages above 35 kilovolt).

(c) Distribution miles (length of lines carrying voltages at or below 35 kilovolt).

(d) Pounds of SF6 and PFC stored in containers, but not in energized equipment, at the 

beginning of the year.

(e) Pounds of SF6 and PFC stored in containers, but not in energized equipment, at the 

end of the year.
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(f) Pounds of SF6 and PFC purchased in bulk from chemical producers or distributors.

(g) Pounds of SF6 and PFC purchased from equipment manufacturers or distributors with 

or inside equipment, including hermetically sealed-pressure switchgear.

(h) Pounds of SF6 and PFC returned to facility after off-site recycling.

(i) Pounds of SF6 and PFC in bulk and contained in equipment sold to other entities.

(j) Pounds of SF6 and PFC returned to suppliers.

(k) Pounds of SF6 and PFC sent off-site for recycling.

(l) Pounds of SF6 and PFC sent off-site for destruction.

(m) State(s) or territory in which the facility lies and total miles of transmission and 

distribution lines located within each state or territory.

(n) The following numbers of pieces of equipment:

(1) New hermetically sealed-pressure switchgear during the year.

(2) New SF6- or PFC-insulated equipment other than hermetically sealed-pressure 

switchgear during the year.

(3) Retired hermetically sealed-pressure switchgear during the year.

(4) Retired SF6- or PFC-insulated equipment other than hermetically sealed-pressure 

switchgear during the year.

§ 98.307 Records that must be retained.

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

information reported and listed in § 98.306.

§ 98.308 Definitions.
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Except as specified in this section, all terms used in this subpart have the same meaning 

given in the Clean Air Act and subpart A of this part.

Facility, with respect to an electric power system, means the electric power system as 

defined in this paragraph. An electric power system is comprised of all electric transmission and 

distribution equipment insulated with or containing SF6 or PFCs that is linked through electric 

power transmission or distribution lines and functions as an integrated unit, that is owned, 

serviced, or maintained by a single electric power transmission or distribution entity (or multiple 

entities with a common owner), and that is located between: (1) The point(s) at which electric 

energy is obtained from an electricity generating unit or a different electric power transmission 

or distribution entity that does not have a common owner, and (2) the point(s) at which any 

customer or another electric power transmission or distribution entity that does not have a 

common owner receives the electric energy. The facility also includes servicing inventory for 

such equipment that contains SF6 or PFCs.

Electric power transmission or distribution entity means any entity that transmits, 

distributes, or supplies electricity to a consumer or other user, including any company, electric 

cooperative, public electric supply corporation, a similar Federal department (including the 

Bureau of Reclamation or the Corps of Engineers), a municipally owned electric department 

offering service to the public, an electric public utility district, or a jointly owned electric supply 

project.

Operator, for the purposes of this subpart, means any person who operates or supervises a 

facility, excluding a person whose sole responsibility is to ensure reliability, balance load or 

otherwise address electricity flow.