PR-312-18209-E01 Methane Emissions from Compressors in Transmission and Storage Subpart W Sources

This white paper provides a step-by-step review of the methodology and data sources for development of compressor methane emission factors (EFs), and develops updated EFs based on Subpart W compressor measurement and leak survey data. The methodology is analogous to that used in a previous GRI/EPA Methane Emissions Study. In all cases, updated T&S compressor emission factors are lower than historical emission factors, and significantly lower in some cases. The updated emission factors provide a current best-estimate of T&S compressors emissions, and can be used to update emission estimates in the EPA Annual GHG Inventory Report, and to provide an alternative method for the annual estimate of compressor emissions for Subpart W.