Natural Gas STAR Methane Challenge Program Continuous Improvement Proposal Update Mains and Services Emission Factors


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EPA POLLUTION PREVENTER '
Natural Gas STAR Methane Challenge Program
Continuous Improvement Proposal
Update Mains and Services Emission Factors
Proposed by: Natural Gas STAR Methane Challenge Program
Date submitted: August 13, 2018
Category of change proposed: Reporting Methodology Update
Summary of proposed change: Update emission factors used for emission and reduction calculations for
Distribution Mains and Services from Part 98, Subpart W factors to U.S. Greenhouse Gas Inventory
factors
Introduction
Through the Natural Gas STAR Methane Challenge Program ("the Program"), EPA encourages Partners to make
ambitious commitments to reduce natural gas (methane) emissions through broad scale implementation of cost-
effective technologies and practices. EPA recognizes ongoing advances in technologies and approaches for
identifying, measuring, and mitigating methane emissions and will consider revising approaches to track,
implement, and report on current commitments through the Continuous Improvement Process.1
Proposed Change
Under the Program, partners in both commitment options (i.e., the Best Management Practice and ONE Future
options) commit to voluntarily submit data detailing their annual methane emissions and reductions as relates to
their program commitments. The calculation methodologies to use, and data elements to report, are detailed in
"Technical Documents" published by the Program.2 The Program is proposing to change the emission factors used
to calculate emissions and reductions for Distribution Mains and Distribution Services in both commitment
options from the relevant factors used in Part 98, Subpart W3 of the Greenhouse Gas Reporting Program (GHGRP)
to those used in the most recent version of the U.S. Greenhouse Gas Inventory (GHGI). The Program has prepared
this Continuous Improvement proposal to allow stakeholders to provide any feedback they may have on this
change.
1	Details available on the Program website at https://www.epa.gov/natural-gas-star-program/methane-challenge-program-
continuous-improvement-fact-sheet
2	Note that EPA reserves the right to update the contents of the Technical Documents at any time to maintain alignment with
definitions and methodologies from Part 98, Subpart W of the Greenhouse Gas Reporting Program (GHGRP) and the U.S.
Greenhouse Gas Inventory (GHGI).
3	40 CFR 98.233(r)
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Details
The GHGI emission factors were updated in 2016 for the 1990-2014 Inventory and use data from a 2015 study by
Lamb et al, in combination with data from GRI/EPA 1996.4,5 For more detailed information on the emission
factors, please see EPA's memo on the update made to the 2016 GHGI.6
The Program proposes to update the methodology for Distribution Mains and Services to use the GHGI emission
factors for 2016, from the 2018 GHGI, for all pipeline materials. These factors are presented in Table 1 below.
Table 1. 2016 Emission Factors in the 2018 GHG Inventory7

Distribution
Mains
(kg/mile/year)
Distribution
Services
(kg/service/year)
Cast Iron
1,157.3
*
Unprotected steel
861.3
14.5
Protected steel
96.7
1.3
Plastic
28.8
0.3
Copper
NA
4.9
*As detailed in the Program Technical Documents, the Unprotected Steel Services emission factor will be used as a proxy for Cast Iron
Services.
This Methane Challenge reporting methodology change would be reflected in newly revised technical documents
which would be published for the first year of reporting for the program.
If you have feedback on this proposal
Send feedback to: Methane Challenge Program Managers at GasSTAR@epa.gov
Feedback due: August 31, 2018
4 Lamb, et al. (2015) Direct Measurements Show Decreasing Methane Emissions from Natural Gas Local Distribution Systems
in the United States. Environmental Science & Technology, Vol. 49 5161-5169.
5 GRI/EPA (1996) Methane Emissions from the Natural Gas Industry. Volume 9: Underground Pipelines.
https://www.epa.gOv/sites/production/files/2016-08/documents/9 underground.pdf
6 EPA (2016) Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2014: Revisions to Natural Gas Distribution
Emissions, https://www.epa.gov/sites/production/files/2016-08/documents/final revision ng distribution emissions 2016-
04-14.pdf
7 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2016, Annex 3.6 (Table 3.6-2), 2016 data,
https://www.epa.gov/sites/production/files/2018-04/2018 ghgi natural gas systems annex tables.xlsx.
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