EPA420-F-02-044
                   UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                                  ANN ARBOR, Ml 48105
September 9, 2002
                                                                           OFFICE OF
                                                                        AIR AND RADIATION

MEMORANDUM
SUBJECT:   Emission Factors for Recreational Marine Diesel Engines

FROM:      Mike Samulski
             Assessment and Standards Division

TO:          Docket A-2000-01
       The U.S. Environmental Protection Agency (EPA) has adopted emission standards for
recreational marine diesel engines. To analyze the environmental benefits expected from these new
standards, we calculated emission factors for these engines, which are summarized in this memo.

Estimated baseline emission rates

In support of the rulemaking finalizing the recreational marine diesel engine emission standards,
EPA estimated average emission rates, given in grams per kilowatt-hour (g/kW-hr), for current
uncontrolled engines.  Table 1 presents the baseline emission rates used in this analysis for new
engines and for engines deteriorated to the regulatory useful life (10 years).  The emission rates are
based on  data collected on 25 recreational marine engines. This data is presented in Table 2.
Deterioration rates are based on the EPA computer model for estimating emissions from nonroad
engines.1
       1 The Draft NONROAD model is available at: www.epa.gov/otaq/nonrdmdl.htm.

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Table 1 - Estimated Baseline Emission Rates [g/kW-hr]

new engine
after 10 years
HC
0.295
0.300
NOx
8.94
9.05
CO
1.27
1.39
PM
0.219
0.270
Table 2 - Emission Data from Recreational Marine Diesel Engines [g/kW-hr]
Rated Power
(kW)
120
132
142
162
164
170
186
209
230
235
265
276
287
321
324
336
336
447
447
474
537
820
1040
1080
1340
Control
Management
electronic
mechanical
mechanical
mechanical
electronic
mechanical
mechanical
mechanical
electronic
mechanical
mechanical
mechanical
electronic
mechanical
mechanical
electronic
electronic
electronic
mechanical
electronic
electronic
electronic
electronic
electronic
electronic
Aftercooling
raw-water
raw-water
separate circuit
raw-water
raw-water
raw-water
raw-water
raw-water
raw-water
raw-water
jacket- water
raw-water
raw-water
raw-water
jacket- water
jacket- water
jacket- water
raw-water
jacket- water
raw-water
jacket- water
separate circuit
jacket- water
separate circuit
separate circuit
HC
0.09
0.07
0.79
0.11
0.28
0.36
0.30
0.42
0.28
0.45
0.58
0.60
0.28
0.37
0.30
0.18
0.09
0.12
0.60
0.34
0.08
0.33
0.09
0.18
0.27
NOx
5.8
4.2
8.6
4.0
5.1
8.1
10.2
10.8
5.5
9.8
10.8
10.7
7.9
7.7
7.9
11.0
11.9
9.3
12.0
7.7
10.7
9.5
9.3
7.6
7.2
CO
0.9
0.2
1.1
0.2
1.6
0.6
1.2
2.3
1.8
1.8
1.4
1.9

0.9
2.9
0.5
-
-
1.5
0.5
-
0.8
-
1.2
0.9
PM
	

-
-

0.20
0.12
0.22
0.39
0.20
-
0.24
0.12
0.23
0.95
0.10
0.16
0.17
0.18
0.07
0.19
0.13
0.21
0.15
0.15

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Projected future emission rates
With the new national emission standards for recreational marine diesel engines, future emission
rates are projected to be lower for HC, NOx, and PM.  Because CO levels are already low and
because the CO standard is intended to be a cap, we do not expect reductions in CO to result from
these standards. Table 3 presents the emission standards and implementation dates which vary
depending on engine size. Table 4 presents the projected controlled emission factors used in the
EPA analysis for new engines and for engines deteriorated to the regulatory useful life (10 years).
Table 3 - Recreational Marine Diesel Emission Standards and Implementation Dates
Displacement
[liters/cylinder]
>37kW, disp<0.9
0.9 < disp< 1.2
1.2 < disp<2.5
2.5 < disp
Implementation
Date
2007
2006
2006
2009
HC+NOx
[g/kW-hr]
7.5
7.2
7.2
7.2
CO
[g/kW-hr]
5.0
5.0
5.0
5.0
PM
[g/kW-hr]
0.4
0.3
0.2
0.2
Table 4 - Projected Controlled Emission Rates [g/kW-hr]

HC
NOx
CO
PM
Rated power >37 kW, Displacement < 0.9 liters/cylinder
new engine
after 10 years
0.181
0.184
6.69
6.72
1.27
1.39
0.219
0.270
0.9 < Displacement < 1.2 liters/cylinder
new engine
after 10 years
0.181
0.184
6.41
6.44
1.27
1.39
0.219
0.270
Displacement >1.2 liters/cylinder
new engine
after 10 years
0.182
0.184
6.42
6.44
1.27
1.39
0.181
0.184

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Projected emission inventory

Total emissions were calculated using Equation 1. Based on data collected in developing the draft
NONROAD model, we use a load factor of 35 percent, an annual usage factor of 200 hours, and an
average operating life of 20 years. The draft NONROAD model also includes population estimates
distributed by rated power.  The metric tons estimate can be converted to standard tons (or short
tons) per year by  multiplying it by 1.1.  EPA's estimates of the projected annual emissions inventory
with and without the new standards are shown in Tables 5 and 6.
Emissions =    ^   population* power* load* annual use * emission factor^
                                                                           Equation 1
Table 5 - Estimated Nationwide Recreational Marine Diesel
Baseline Emissions Inventory [short tons per year]
Calendar Year
2000
2010
2020
2030
HC
1,270
1,650
2,030
2,410
NOx
38,000
49,400
60,800
72,200
CO
5,850
7,610
9,360
11,100
PM
1,000
1,300
1,600
1,900
Table 6 - Estimated Nationwide Recreational Marine Diesel
Controlled Emissions Inventory [short tons per year]
Calendar Year
2000
2010
2020
2030
HC
1,270
1,490
1,450
1,510
NOx
38,000
45,800
48,000
52,200
CO
5,850
7,610
9,360
11,100
PM
1,000
1,230
1,310
1,420

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