91.207—Credit calculation and manufacturer compliance with emission standards.
(a)
For each engine family, certification emission credits (positive or negative) are to be calculated according to the following equation and rounded, in accordance with ASTM E29-93a, to the nearest gram. ASTM E29-93a has been incorporated by reference. See § 91.6. Consistent units are to be used throughout the equation. The following equation is used to determine hydrocarbon plus oxides of nitrogen credit status for an engine family, whether generating positive credits or negative credits:
Where:
sales = the number of eligible sales tracked to the point of first retail sale for the given engine family during the model year. Annual production projections are used to project credit availability for initial certification. Actual sales volume is used in determining actual credits for end of-year compliance determination.
t = time in model years
Power = the average power of an engine family in kW (sales weighted). The power of each configuration is the rated output in kilowatts as determined by SAE J1228. This procedure has been incorporated by reference. See § 91.6.
max actual life = maximum actual life specific to the power rating and the application; max actual life = 2μlife
μlife = average actual life in years, specific to the power rating and the application as given below.
Power = as defined above.
μuse = mean use in hours per year. For outboard engines,
μuse = 34.8 hrs /yr. For personal watercraft, μuse = 77.3 hrs/yr;
S(t) = cumulative fraction survived at time t;
S(t) = exp −(0.906 × t/µlife)4
STD = the current and applicable marine SI engine emission standard in grams per kilowatt hour as determined in § 91.104.
FEL = the family emission limit for the engine family in grams per kilowatt hour.
(b)
Manufacturer compliance with the corporate average emission standard is determined on a corporate average basis at the end of each model year. A manufacturer is in compliance when the sum of positive and negative emission credits it holds is greater than or equal to zero, except as allowed under paragraph (c) of this section.
(i)
For model year 1998, a manufacturer is in compliance when the sum of positive credits and negative emission credits it holds is greater than or equal to zero, including
(A)
Credits generated in MY 1998 exceed 70% of the negative credits generated in MY 1998. The remaining negative credits (up to 30% of the total negative credits) must be banked.
(ii)
For model year 1999, a manufacturer is in compliance when the positive credits generated in MY 1999 exceed the sum of 80% of the negative credits generated in MY 1999 and the negative credits banked in 1998. The remaining negative credits (up to 20% of the total negative credits) must be banked.
(iii)
For model year 2000, a manufacturer is in compliance when the sum of positive and negative emission credits it holds is greater than or equal to zero, including
(B)
Any adjustments to credits based on adjustments to FELs resulting from requirements in § 91.118(h)(1)(i). Manufacturers do not have to recalculate compliance for model years 1998 and 1999.
(2)
Personal watercraft engines. (i) For model year 1999, a manufacturer is in compliance when the positive credits generated in MY 1999 exceed 50% of the negative credits generated in MY 1999. The remaining negative credits (up to 50% of the total negative credits) must be banked.
(ii)
For model year 2000, a manufacturer is in compliance when the sum of positive and negative emission credits it holds is greater than or equal to zero, including
(B)
Any adjustments to credits based on adjustments to FELs resulting from requirements in § 91.118(h)(1)(i). Manufacturers do not have to recalculate compliance for model year 1999.
(d)
When a manufacturer is not in compliance, the manufacturer will be in violation of these regulations and EPA may void ab initio the certificates of engine families for which the manufacturer has not obtained sufficient positive emission credits pursuant to § 91.123.
(e)
Notwithstanding other provisions of this part, for model years beginning with model year 2000, a manufacturer having a negative credit balance during one period of up to four consecutive model years will not be considered to be in noncompliance in a model year up through and including model year 2009 where:
(1)
The manufacturer has a total annual production of engines subject to regulation under this part of 1000 or less; and
(2)
The manufacturer has not had a negative credit balance other than in three immediately preceding model years, except as permitted under paragraph (c) of this section; and
(3)
The FEL(s) of the family or families produced by the manufacturer are no higher than those of the corresponding family or families in the previous model year, except as allowed by the Administrator; and
(4)
The manufacturer submits a plan acceptable to the Administrator for coming into compliance with future model year standards including projected dates for the introduction or increased sales of engine families having FEL(s) below standard and projected dates for discontinuing or reducing sales of engines having FEL(s) above standard; and
(5)
(i)
The manufacturer has set its FEL using emission testing as prescribed in subpart E of this part; or
(ii)
The manufacturer has set its FEL based on the equation and provisions of § 91.118(h)(1)(i) and the manufacturer has submitted appropriate test data and revised its FEL(s) and recalculated its credits pursuant to the provisions of § 91.118(h)(1); or
(iii)
The manufacturer has set its FEL using good engineering judgement, pursuant to the provisions of § 91.118(h)(1)(ii) and (h)(2).