Q542. Can EPA clarify the flow rates and conditions required to be reported in 40 CFR 98.236(d) for acid gas removal units?

A542. In general, there are three flow rates that may be reported for AGRs, depending on the Calculation Method selected.. The first set of reporting requirements are effective until December 31, 2024 (i.e., through Reporting Year 2024).

• For the following reporting requirements, reporters should enter the total quantity of gas flow into the AGR to be treated (i.e., the feed rate):
  • 40 CFR 98.236(d)(1)(ii), for all AGRs: Total feed rate entering the acid gas removal unit, in million cubic feet per year. This quantity may be reported in million actual cubic feet per year or million standard cubic feet per year.
  • 40 CFR 98.236(d)(2)(ii)(D), for AGRs using Calculation Method 3, Equation W-4A: Total annual volume of natural gas flow into the acid gas removal unit in cubic feet at actual conditions.
  • 40 CFR 98.236(d)(2)(iii)(D), for AGRs using Calculation Method 4: Natural gas flow rate, in standard cubic feet per minute.
• For the following reporting requirement, reporters should enter the total quantity of treated natural gas exiting the AGR:
  • 40 CFR 98.236(d)(2)(ii)(D), for AGRs using Calculation Method 3, Equation W-4B: total annual volume of natural gas flow out of the acid gas removal unit in cubic feet at actual conditions.
• For the following reporting requirement, reporters should enter the total quantity of gas vented from the AGR. This stream is mostly acid gas (including CO₂) removed from the feed natural gas.
  • 40 CFR 98.236(d)(2)(i)(B), for AGRs using Calculation Method 1 or 2: Annual volume of gas vented from the acid gas removal unit, in cubic feet. This quantity may be reported in actual cubic feet or standard cubic feet.

There are several revisions to these requirements that become effective on January 1, 2025 (i.e., beginning with Reporting Year 2025). The resulting flow rate reporting requirements are provided below.

• For the following reporting requirements, reporters should enter the total quantity of gas flow into the AGR to be treated (i.e., the feed rate):
  • 40 CFR 98.236(d)(1)(ii), for all AGRs: Total feed rate entering the acid gas removal unit, in million standard cubic feet per year. (Previously reporters had the option of reporting this quantity in million actual cubic feet per year.)
  • 40 CFR 98.236(d)(2)(ii)(H), for AGRs using Calculation Method 3, Equation W-4A or Equation W-4C: Total annual volume of natural gas flow into the acid gas removal unit in cubic feet at actual conditions. Reporters must also provide the temperature and pressure that corresponds to this flow rate (40 CFR 98.236(d)(2)(ii)(I) and (J), respectively).
  • 40 CFR 98.236(d)(2)(iii)(D), for AGRs using Calculation Method 4: Annual average natural gas feed flow rate, in standard cubic feet per minute.
• For the following reporting requirement, reporters should enter the total quantity of treated natural gas exiting the AGR:
  • 40 CFR 98.236(d)(2)(ii)(K), for AGRs using Calculation Method 3, Equation W-4B or Equation W-4C: Total annual volume of natural gas flow out of the acid gas removal unit in cubic feet at actual conditions. Reporters must also provide the temperature and pressure that corresponds to this flow rate (40 CFR 98.236(d)(2)(ii)(L) and (M), respectively).
• For the following reporting requirement, reporters should enter the total quantity of gas vented from the AGR. This stream is mostly acid gas (including CO₂) removed from the feed natural gas.
  • 40 CFR 98.236(d)(2)(i)(C), for AGRs using Calculation Method 1 or 2: Annual volume of gas vented from the acid gas removal unit, in cubic feet. Reporters must also provide the temperature and pressure that corresponds to this flow rate (40 CFR 98.236(d)(2)(i)(D) and (E), respectively).