Q487. How should an onshore natural gas processing facility report emissions from a membrane plant where CO2 is removed from sweet gas and vented?
A487. Note that per 40 CFR 98.6, sour natural gas is natural gas containing concentrations of hydrogen sulfide and/or carbon dioxide that exceed the concentrations specified for commercially saleable natural gas. Therefore, if a membrane unit is used to remove CO2 from natural gas that meets this definition of sour natural gas, then emissions must be calculated and reported as specified in 40 CFR 98.232(d)(5) and 40 CFR 98.233(d), as this process and its associated vented emissions meet the definitions of acid gas removal unit and acid gas removal vent emissions in 40 CFR 98.238, respectively. Please see EPA-HQ-OAR-2009-0923-1298-18 in the Response To Comments (pages 1719 - 1720) https://www.regulations.gov/document?D=EPA-HQ-OAR-2009-0923-3608 for further details on the definitions of sweet and sour gas.
If the hydrogen sulfide and carbon dioxide concentrations both meet the specifications for commercially saleable natural gas prior to the membrane, the CO2 emissions removed by the membrane plant are not reported under subpart W.
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Source: EPA, Frequently Asked Questions, Petroleum and Natural Gas Systems, July 2011, [http://www.epa.gov/ghgreporting/documents/pdf/2011/documents/Subpart-W-additional-faq.pdf]. Answer updated to include H2S and exceeds language. Revised 01/14/2025 per Subpart W FAQ Update Approval / Publishing History: Version 3, Revised to update URLs per direction from K. Sibold, 9/27/2012. Version 4 , 01/15/2025 per S. Jackson-Dixon Expiration: none Relevant Subpart: W, Onshore Gas Processing. |
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