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.

Other large release events, such as abnormal or atypical release events, are not currently subject to reporting to the GHGRP. However, on August 1, 2023, the EPA proposed amendments to Subpart W of the GHGRP adding a new source category called “Other Large Release Events” that was proposed to be applicable to all ten Subpart W segments. If finalized as proposed, abnormal or atypical release events that are not currently captured under Subpart W will be subject to reporting under the new Other Large Release Events emission source category.