Regulations last checked for updates: Feb 21, 2025

Title 40 - Protection of Environment last revised: Nov 21, 2025
All TitlesTitle 40Chapter IPart 98Subpart NNAppendix - Table NN-2 to Subpart NN of Part 98—Default Factors for Calculation Methodology 2 of This Subpart
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Appendix - Table NN-2 to Subpart NN of Part 98—Default Factors for Calculation Methodology 2 of This Subpart
Fuel Unit Default CO2 emission factor
(MT CO2/Unit) 1
Natural GasMscf0.0544
PropaneBarrel0.241
Normal butaneBarrel0.281
EthaneBarrel0.170
IsobutaneBarrel0.270
Pentanes plusBarrel0.324

1 Conditions for emission value presented in MT CO2/bbl are 60 °F and saturation pressure.

[78 FR 71977, Nov. 29, 2013, as amended at 79 FR 3508, Jan. 22, 2014; 81 FR 89270, Dec. 9, 2016]
authority: 42 U.S.C. 7401-7671q.
source: 74 FR 56374, Oct. 30, 2009, unless otherwise noted.
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