PR-312-10202-E01 Characterization of Natural Gas Pneumatic Device Types Vent Rates

Abstract

For the onshore natural gas transmission compression and storage segments, natural gas pneumatic device venting is included as one of reportable sources required under Subpart W "Petroleum and Natural Gas Systems" of the GHG Mandatory Reporting Rule (MRR). In the natural gas transmission and storage industry, pneumatic devices are used to control process conditions such as temperature, pressure, flow and liquid level. A count and categorization into continuous high-, intermittent-, and continuous low-bleed pneumatic devices is required to calculate GHG emissions from pneumatic controllers. EPA has not specified a method to classify each pneumatic device, and Subpart W instructs reporters to "determine the type of pneumatic device using engineering estimates based on best available information." Thus, companies must determine which category is appropriate for each pneumatic device, and the device count must be updated annually. This report includes an introduction and background on the GHG Mandatory Reporting Rule (MRR) and pneumatic device source in Section 1. Section 2 provides a discussion of the project objectives and a discussion of the efforts to compile pneumatic device information. Section 3 provides a comparison of the default MRR GRI-EPA Tier 2 pneumatic device emission factors to other published rates. Section 4 explores pneumatic device types used in natural gas transmission and storage. Section 5 provides a summary of the Subpart W pneumatic device emission calculation methodology. Section 6 provides a summary of vendor survey results including the Excel calculation and device lookup tools. Sections 7 and 8 provide initial conclusions from the vendor survey and nomenclature and categorization issues, respectively. Section 8 also includes a discussion of factors that complicate classification and options to consider when resolving this for Subpart W reporting - and new complication associated with parallel definitions for Subpart OOOO control rule. The document includes a macro enabled spreadsheet that can be used to estimate emission rates from pneumatic controllers.