Q856. Are unintentional natural gas releases such as those resulting from accidental releases from transmission pipelines or well blowouts subject to reporting under the Greenhouse Gas Reporting Program (GHGRP)?

A856. Onshore natural gas transmission pipeline facilities must report emissions of carbon dioxide and methane from blowdown vent stacks to the GHGRP if facility-wide annual emissions are 25,000 metric tons of carbon dioxide equivalents (mtCO2e) or greater. This requirement applies to blowdown vent stack emissions from the depressurization of equipment for both planned and emergency shutdowns.

However, prior to RY 2025, some types of accidental or atypical release events, such as well blowouts, are not subject to reporting to the GHGRP.    Starting in RY 2025, the EPA added a new source category 40 CFR 98.233(y) called “Other Large Release Events” that is applicable to all ten Subpart W segments. Accidental, abnormal, or atypical release events that have methane emission rates exceeding 100 kg/hr will be subject to reporting under the new Other Large Release Events emission source category if facility-wide annual emissions are 25,000 mtCO2e or greater. Thus, starting in RY 2025, unintentional natural gas releases such as those resulting from accidental releases from transmission pipelines or well blowouts are reportable under the GHGRP and must be included in determining if the facility meets the 25,000 mtCO2e threshold.