AGA Comments Support Updated Emission Factors for EPA Voluntary Methane Challenge Program

In comments filed August 31, 2018, AGA supported EPA’s proposal to update the methane emission factors used in the voluntary Natural Gas STAR/Methane Challenge Program for reporting emissions from natural gas distribution mains and services. We appreciate that EPA is now proposing to adopt new, updated emission factors for the voluntary Methane Challenge Program that are based on recent methane research, such as the Washington State University (WSU) multi-city distribution peer-reviewed paper by Dr. Brian Lamb. These updated emission factors for mains and services are already incorporated in EPA’s annual Greenhouse Gas Inventory (GHGI). We have requested this change in the past, and we support it now, with just a few suggested clarifications to explain the changes. First, we asked EPA to explain that the older emission factors are still used in company reporting under the mandatory Subpart W GHG Reporting Rule (40 C.F.R. Part 98, Subpart W), which will result in some inconsistencies. We have asked EPA to commence a notice and comment rulemaking to update the Subpart W emission factors to eliminate these inconsistencies. Second, while other emission factors are lower, the new emission factor for protected steel is actually higher. It may appear, erroneously, that some companies have an upward trend in emissions simply because the GHGI emission factor for protected steel is higher than the older emission factor. Confusion could be prevented among those reading the Methane Challenge results by noting that this does not indicate that actual emissions from a particular company’s protected steel pipes have increased year over year, and by making an appropriate change to carry a consistent emission factor through the relevant time series, as is done for the GHGI.

 EPA Methane Challenge Proposal