40 CFR §98.63

1. (a)The annual value of each PFC compound (CF4, C2F6) shall be estimated from the sum of monthly values using Equation F-1 of this section:
2. (b)Use Equation F-2 of this section to estimate CF4 emissions from anode effect duration or Equation F-3 of this section to estimate CF4 emissions from overvoltage, and use Equation F-4 of this section to estimate C2F6 emissions from anode effects from each prebake and Søderberg electrolysis cell.
3. (c)You must calculate and report the annual process CO2 emissions from anode consumption during electrolysis and anode baking of prebake cells using either the procedures in paragraph (d) of this section, the procedures in paragraphs (e) and (f) of this section, or the procedures in paragraph (g) of this section.
4. (d)Calculate and report under this subpart the process CO2 emissions by operating and maintaining CEMS according to the Tier 4 Calculation Methodology in § 98.33(a)(4) and all associated requirements for Tier 4 in subpart C of this part (General Stationary Fuel Combustion Sources).
5. (e)Use the following procedures to calculate CO2 emissions from anode consumption during electrolysis:
   1. (1)For Prebake cells: you must calculate CO2 emissions from anode consumption using Equation F-5 of this section:
   2. (2)For Søderberg cells you must calculate CO2 emissions using Equation F-6 of this section:
6. (f)Use the following procedures to calculate CO2 emissions from anode baking of prebake cells:
   1. (1)Use Equation F-7 of this section to calculate emissions from pitch volatiles combustion.
   2. (2)Use Equation F-8 of this section to calculate emissions from bake furnace packing material.
7. (g)If process CO2 emissions from anode consumption during electrolysis or anode baking of prebake cells are vented through the same stack as any combustion unit or process equipment that reports CO2 emissions using a CEMS that complies with the Tier 4 Calculation Methodology in subpart C of this part (General Stationary Fuel Combustion Sources), then the calculation methodology in paragraphs (d) and (e) of this section shall not be used to calculate those process emissions. The owner or operation shall report under this subpart the combined stack emissions according to the Tier 4 Calculation Methodology in § 98.33(a)(4) and all associated requirements for Tier 4 in subpart C of this part (General Stationary Fuel Combustion Sources).