This section contains standards and other regulations applicable to the emission of the air pollutant defined as the aggregate group of six greenhouse gases: Carbon dioxide, nitrous oxide, methane, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. This section describes the applicable CO2, N2O, and CH4 standards for engines. These standards do not apply for engines used in vehicles subject to (or voluntarily certified to) the CO2, N2O, and CH4 standards for vehicles specified in 40 CFR 86.1819.

(a) Emission standards. Emission standards apply for engines measured using the test procedures specified in subpart F of this part as follows:

(1) CO2 emission standards in this paragraph (a)(1) apply based on testing as specified in subpart F of this part. The applicable test cycle for measuring CO2 emissions differs depending on the engine family's primary intended service class and the extent to which the engines will be (or were designed to be) used in tractors. For medium and heavy heavy-duty engines certified as tractor engines, measure CO2 emissions using the steady-state duty cycle specified in 40 CFR 86.1362 (referred to as the ramped-modal cycle, or RMC, even though emission sampling involves measurements from discrete modes). This is intended for engines designed to be used primarily in tractors and other line-haul applications. Note that the use of some RMC-certified tractor engines in vocational applications does not affect your certification obligation under this paragraph (a)(1); see other provisions of this part and 40 CFR part 1037 for limits on using engines certified to only one cycle. For medium and heavy heavy-duty engines certified as both tractor and vocational engines, measure CO2 emissions using the steady-state duty cycle and the transient duty cycle (sometimes referred to as the FTP engine cycle), both of which are specified in 40 CFR part 86, subpart N. This is intended for engines that are designed for use in both tractor and vocational applications. For all other engines (including engines meeting spark-ignition standards), measure CO2 emissions using the appropriate transient duty cycle specified in 40 CFR part 86, subpart N.

(i) The CO2 standard is 627 g/hp-hr for all spark-ignition engines for model years 2016 through 2020. This standard continues to apply in later model years for all spark-ignition engines that are not heavy heavy-duty engines.

(ii) The following CO2 standards apply for compression-ignition engines (in g/hp-hr):

(iii) The following CO2 standards apply for compression-ignition engines and all heavy heavy-duty engines (in g/hp-hr):

(iv) You may certify spark-ignition engines to the compression-ignition standards for the appropriate model year under this paragraph (a). If you do this, those engines are treated as compression-ignition engines for all the provisions of this part.

(2) The CH4 emission standard is 0.10 g/hp-hr when measured over the applicable transient duty cycle specified in 40 CFR part 86, subpart N. This standard begins in model year 2014 for compression-ignition engines and in model year 2016 for spark-ignition engines. Note that this standard applies for all fuel types just like the other standards of this section.

(3) The N2O emission standard is 0.10 g/hp-hr when measured over the transient duty cycle specified in 40 CFR part 86, subpart N. This standard begins in model year 2014 for compression-ignition engines and in model year 2016 for spark-ignition engines.

(b) Family Certification Levels. You must specify a CO2 Family Certification Level (FCL) for each engine family. The FCL may not be less than the certified emission level for the engine family. The CO2 Family Emission Limit (FEL) for the engine family is equal to the FCL multiplied by 1.03.

(c) Averaging, banking, and trading. You may generate or use emission credits under the averaging, banking, and trading (ABT) program described in subpart H of this part for demonstrating compliance with CO2 emission standards. Credits (positive and negative) are calculated from the difference between the FCL and the applicable emission standard. As described in §1036.705, you may use CO2 credits to certify your engine families to FELs for N2O and/or CH4, instead of the N2O/CH4 standards of this section that otherwise apply. Except as specified in §§1036.150 and 1036.705, you may not generate or use credits for N2O or CH4 emissions.

(d) Useful life. The exhaust emission standards of this section apply for the full useful life, expressed in service miles, operating hours, or calendar years, whichever comes first. The useful life values applicable to the criteria pollutant standards of 40 CFR part 86 apply for the standards of this section, except that the spark-ignition standards and the standards for model year 2021 and later light heavy-duty compression-ignition engines apply over a useful life of 15 years or 150,000 miles, whichever comes first.

(e) Applicability for testing. The emission standards in this subpart apply as specified in this paragraph (e) to all duty-cycle testing (according to the applicable test cycles) of testable configurations, including certification, selective enforcement audits, and in-use testing. The CO2 FCLs serve as the CO2 emission standards for the engine family with respect to certification and confirmatory testing instead of the standards specified in paragraph (a)(1) of this section. The FELs serve as the emission standards for the engine family with respect to all other duty-cycle testing. See §§1036.235 and 1036.241 to determine which engine configurations within the engine family are subject to testing. Note that engine fuel maps and powertrain test results also serve as standards as described in §1036.535, §1036.540, §1036.630 and 40 CFR 1037.550.

(f) Multi-fuel engines. For dual-fuel, multi-fuel, and flexible-fuel engines, perform exhaust testing on each fuel type (for example, gasoline and E85).

(1) This paragraph (f)(1) applies where you demonstrate the relative amount of each fuel type that your engines consume in actual use. Based on your demonstration, we will specify a weighting factor and allow you to submit the weighted average of your emission results. For example, if you certify an E85 flexible-fuel engine and we determine the engine will produce one-half of its work from E85 and one-half of its work from gasoline, you may apply a 50 percent weighting factor to each of your E85 and gasoline emission results.

(2) If you certify your engine family to N2O and/or CH4 FELs the FELs apply for testing on all fuel types for which your engine is designed, to the same extent as criteria emission standards apply.