Costs of Emission Reduction Technologies 

for Category 3 Marine Engines 

Final Report 
 

 

Costs of Emission Reduction Technologies 


for Category 3 Marine Engines 


Final Report
 

Assessment and Standards Division 

Office of Transportation and Air Quality 

U.S. Environmental Protection Agency 

Prepared for EPA by
 

ICF International
 

EPA Contract No. EP-C06094
 

Work Assignment No. WA1-8
 

NOTICE 

This technical report does not necessarily represent final EPA decisions or 


positions. It is intended to present technical analysis of issues using data 


that are currently available. The purpose in the release of such reports is to 


facilitate the exchange of technical information and to inform the public of 


technical developments.
 

EPA-420-R-09-008 

May 2009 
 

Table of Contents 

1. Introduction ........................................................................................................................1-1
 

2. Technology Description ....................................................................................................2-3
 

2.1. Baseline Technologies ..............................................................................................2-3
 

2.1.1. Low-Speed Engines.............................................................................................................................2-4
 

2.1.2. Medium-Speed Engines .....................................................................................................................2-4
 

2.1.3. Typical Ship Characteristics ..............................................................................................................2-4
 

2.2. Advanced Technologies ............................................................................................2-5
 

2.2.1. Tier I Retrofit Technologies................................................................................................................2-5
 

2.2.2. Tier II Technologies..............................................................................................................................2-6
 

2.2.3. Tier III Technologies ..........................................................................................................................2-11
 

2.3. Fuel Switching .........................................................................................................2-23
 

2.3.1. Vessel fuel systems ...........................................................................................................................2-23
 

2.3.2. Potential vessel modifications associated with fuel switching..............................................2-25
 

2.3.3. Modifications for fuel switching.......................................................................................................2-28
 

2.3.4. Scenarios analyzed and cost methodology................................................................................2-29
 

3. Economic Impact ...............................................................................................................3-1
 

3.1. Cost Estimation Methodology....................................................................................3-1
 

3.1.1. Hardware Cost to Manufacturer.......................................................................................................3-1
 

3.1.2. Fixed Cost to Manufacturer ...............................................................................................................3-1
 

3.1.3. Fuel Economy ........................................................................................................................................3-2
 

3.2. Retrofit Tier I Technology Costs ................................................................................3-3
 

3.3. Tier II Technology Costs............................................................................................3-4
 

3.4. Tier III Technology Costs...........................................................................................3-6
 

3.4.1. Engine Modifications............................................................................................................................3-6
 

3.4.2. Fumigation...............................................................................................................................................3-7
 

3.4.3. Fuel Emulsification ...............................................................................................................................3-9
 

3.4.4. Direct Water Injection ........................................................................................................................3-11
 

3.4.5. Exhaust Gas Recirculation...............................................................................................................3-13
 

3.4.6. Selective Catalytic Reduction .........................................................................................................3-15
 

3.4.7. Sea Water Scrubbers ........................................................................................................................3-17
 

3.5. Fuel Switching Hardware Costs ..............................................................................3-19
 

3.6. Differential Fuel Consumption .................................................................................3-22
 

3.7. IMO Testing Costs...................................................................................................3-23
 

ICF International i U.S. Environmental Protection Agency
 

EPA Contract EP-C-06-094, WA 2-08 April 20099
 
 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Table of Contents 

List of Figures 

Figure 1-1. Proposed IMO Standards ........................................................................................................................ 1-2
 

Figure 2-1. Cross-Sectional diagrams of Different Nozzle Sac Designs .................................................................... 2-8
 

Figure 2-2. Wärtsilä Common Rail Fuel Injection System ........................................................................................ 2-10
 

Figure 2-3. Comparison between SCR and HAM..................................................................................................... 2-12
 

Figure 2-3. HAM System.......................................................................................................................................... 2-13
 

Figure 2-4. SAM System .......................................................................................................................................... 2-14
 

Figure 2-5. Wetpac H System .................................................................................................................................. 2-15
 

Figure 2-6. Pressurized Fuel Emulsification System................................................................................................ 2-16
 

Figure 2-7. DWI Unit for Pressurizing Water and injectors....................................................................................... 2-17
 

Figure 2-8. MAN Diesel EGR Scrubber.................................................................................................................... 2-19
 

................................................................................................................................................................................. 2-20
 

Figure 2-9. Example of Urea SCR System for a 4-stroke engine with the reactor placed downstream of turbocharger
 

Figure 2-10. Urea SCR system with Reactor Installation before Turbocharger........................................................ 2-21
 

Figure 2-11. Seawater Scrubbing System with EcoSilencer® for a “Super Yacht” design for engines up to 3.5MW 2-22
 

Figure 2-12. Typical Shipboard Unifuel Delivery System ......................................................................................... 2-24
 

Figure 2-13. Typical Fuel Tank and Delivery Systems ............................................................................................. 2-25
 

Figure 2-14. MAN B&W’s Fuel Oil System No. 1 ..................................................................................................... 2-30
 

List of Tables 

Table 2-1. Engine Modifications Currently In-Use to Meet MARPOL Emission Levels .............................................. 2-3
 

Table 2-2. Average Engine Characteristics Used in this Study .................................................................................. 2-4
 

Table 2-3. Average Ship Characteristics by Ship Type............................................................................................. 2-5
 

Table 2-4. Average Auxiliary Engine Load Factors and Hotelling Times by Ship Type.............................................. 2-5
 

Table 2-5. Key Attributes and Benefits to the Sulzer RT-flex Common Rail System................................................ 2-10
 

Table 2-6. Benefits and Limitations of Wärtsilä’s DWI Technology .......................................................................... 2-18
 

Table 2-7. Typical on-board storage for heavy fuel oil and distillate fuels by vessel type ........................................ 2-27
 

Table 2-8. Fuel Use per Call for Various ECA Distances (Metric Tonnes)............................................................... 2-27
 

Table 3-1. Labor Rates .............................................................................................................................................. 3-1
 

Table 3-2. Annual Research and Development Costs ............................................................................................... 3-2
 

Table 3-3. Average Load Factors............................................................................................................................... 3-2
 

Table 3-4. Cost of Retrofit Kits ................................................................................................................................... 3-3
 

Table 3-5. Differential Costs for Engine Modifications to Meet Tier II Emission Levels.............................................. 3-4
 

Table 3-6. Common Rail Fuel Injection Costs for Mechanically Injected Engines...................................................... 3-5
 

Table 3-7. Common Rail Fuel Injection Costs for Electronic Engines ........................................................................ 3-6
 

Table 3-8. Differential Engine Modifications Costs to Meet Tier III Emission Levels.................................................. 3-7
 

Table 3-9. Fumigation Costs ...................................................................................................................................... 3-8
 

Table 3-10. Fumigation Water Tank Costs................................................................................................................. 3-9
 

Table 3-11. Fumigation Distilled Water Costs ............................................................................................................ 3-9
 

Table 3-12. Fuel Emulsification Costs...................................................................................................................... 3-10
 

Table 3-13. Emulsification Water Tank Costs .......................................................................................................... 3-11
 

Table 3-14. Emulsification Distilled Water Costs...................................................................................................... 3-11
 

Table 3-15. Direct Water Injection Costs.................................................................................................................. 3-12
 

Table 3-16. DWI Water Tank Costs ......................................................................................................................... 3-13
 

Table 3-17. DWI Distilled Water Costs..................................................................................................................... 3-13
 

Table 3-18. Exhaust Gas Recirculation Costs.......................................................................................................... 3-14
 

Table 3-19. Sludge Tank Costs................................................................................................................................ 3-15
 

Table 3-20. Selective Catalytic Reduction Costs...................................................................................................... 3-16
 

Table 3-21. Urea Tank Costs ................................................................................................................................... 3-17
 

Table 3-22. Urea Costs ............................................................................................................................................ 3-17
 

Table 3-23. Sea Water Scrubber Costs ................................................................................................................... 3-18
 

Table 3-24. Sludge Tank Costs................................................................................................................................ 3-19
 

Table 3-26. Case 1 Fuel Switching Costs (New Construction)................................................................................. 3-20
 

Table 3-27. Additional Fuel Tank Storage Costs...................................................................................................... 3-21
 

Table 3-28. Case 2 Fuel Switching Costs (Retrofits)................................................................................................ 3-22
 

Table 3-29. Hourly fuel use change estimated for a one percent change in brake specific fuel consumption.......... 3-23
 

ICF International ii U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

1. Introduction 

In December 2007, EPA published an Advanced Notice of Proposed Rulemaking to enact more 

stringent exhaust emission standards for engines on ocean going vessels.1 New NOx and SOx 

exhaust emission standards were discussed for engines on Category 3 marine vessels.2 

Two new tiers of NOx standards have recently been adopted by the IMO. Tier II NOx standards 

are roughly 20 percent lower than the existing Tier I NOx standards set by the International 

Maritime Organization in Annex VI.3

 To meet these standards, in-cylinder emission control 

approaches such as electronically controlled high pressure common rail fuel systems, 

turbocharger optimization, compression ratio changes and electronically controlled exhaust 

valves could be used. Tier III NOx standards which only apply in designated Emission Control 

Areas are roughly 80 percent below Tier I NOx standards and would likely require exhaust 

aftertreatment such as selective catalytic reduction (SCR). Other approaches that may be 

considered to reduce NOx emissions from Category 3 vessel engines are exhaust gas 

recirculation and water technologies such as direct water injection or fumigation. 

In addition to these NOx standards for new Category 3 marine vessel engines, standards were 

adopted by the IMO for NOx limits for existing engines due to the very long life of ocean going 

vessels and the availability of known in-cylinder technical modifications such as slide valve fuel 

injectors and injection timing retard that provide significant and cost-effective NOx reductions. It 

is believed that engines built in 1990 through 1999 are compatible with these lower NOx 

components. The standards require that engines would need to be modified to achieve a 20 

percent reduction in NOx emissions from their existing baseline emission rates. 

Reductions in SOx and PM are expected to be met primarily through two approaches. The first 

would be to operate the engines on a lower sulfur distillate fuel. Category 3 marine engines 

typically operate on heavy fuel oil with a sulfur content of 2.7 percent. Significant SOx and PM 

reductions could be achieved using distillate fuels with a sulfur content of 0.1 percent. Fuel 

costs will be estimated through a separate effort. However, costs due to vessel modifications 

will be considered here. For instance, if a lower sulfur fuel is used only near U.S. coasts, the 

vessel must be capable of switching between heavy fuel oil and distillate fuel. In the case of a 

vessel converting exclusively to distillate fuel, cost savings may be achieved with a greatly 

simplified fuel treatment system on board the vessel. Alternatively, the vessel could continue to 

operate on high sulfur fuel if it were equipped with an exhaust gas scrubber to remove SOx from 

the exhaust. 

This report includes descriptions of baseline and likely emission control technologies expected 

to be used to meet Tier II and Tier III emission standards, the lower sulfur fuel requirement for 

designated Emission Control Areas, as well as the related costs for application, usage, and 

maintenance of these technologies. 

1 Environmental Protection Agency, “Control of Emissions from New Marine Compression-Ignition Engines at or 

Above 30 Liters per Cylinder; Proposed Rule,” Federal Register / Vol. 72, No. 235 / Friday, December 7, 2007. 

Available at http://www.epa.gov/fedrgstr/EPA-AIR/2007/December/Day-07/a23556.pdf 

2 Category 3 marine vessel refers to ocean going vessels which have at least one Category 3 marine diesel engine 

with a displacement of at least 30 liters per cylinder. The standard will apply to all engines on a Category 3 marine 

vessel including auxiliary engines which are typically Category 2 (5 to 30 liters per cylinder). 3

 Annex VI of MARPOL 73/78: Regulations for the Prevention of Air Pollution from Ships and NOx Technical Code 

from the IMO (ISBN 92-801-6089-3) (IMO Sales Number IMO-664E) 

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EPA Contract EP-C-06-094, WA 2-08 April 20099
 
 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Introduction 

Figure 1-1. Proposed IMO Standards 

Source: MAN Diesel SE4 

4 MAN Diesel, “Exhaust Gas Emission Control Today and Tomorrow,” August 19, 2008, available at 

http://www.manbw.com/article_009187.html 

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EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

2. Technology Description 

Category 3 marine diesel engines are currently being built to meet Tier I IMO MARPOL Annex 

VI emission standards. A brief description of the baseline technologies is given below as well 

as descriptions of the various technology improvements used to obtain lower emission levels. 

2.1. Baseline Technologies 

Current engines built to meet MARPOL Tier I emission levels are considered baseline 

technologies for this analysis. Generally Tier I NOx emission levels are estimated as 11 percent 

below Tier 0 emission levels.5

 Engine modifications currently being used by manufacturers are 

listed in Table 2-1. To assess the costs of new technologies needed to reduce emissions below 

future MARPOL levels, average engine characteristics have been defined. In order to account 

for different technology costs that are associated with different size and/or types of engines, a 

number of ‘average engines’ were developed; these engines with ‘typical’ characteristics are 

listed in Table 2-2. Both low-speed and medium-speed Category 3 engines are represented. 

Estimated costs would need to be adjusted for larger or smaller engines of each type. 

Table 2-1. Engine Modifications Currently In-Use to Meet MARPOL Emission Levels6 

Component or 

Operation Changed Change Parameter Affected 

Low-Speed 

Engines 

Medium-Speed 

Engines 

turbocharger improved efficiency, 

schemes for variable flow SFC, intake pressure yes yes 

Intercooler improved efficiency air inlet temperature yes yes 

air inlet port redesigned shape swirl maybe yes 

cylinder head redesign shape swirl, compression ratio maybe yes 

piston crown redesigned piston crown 

shape swirl, compression ratio no yes 

injection pressure increase atomization yes yes 

injectors redesign sac volume, injection 

rate shaping yes yes 

nozzle smaller holes, more holes, 

cleaner holes, etc. spray pattern changes possibly yes 

injection timing retard and/or vary with 

load 

peak cylinder 

temperature yes yes 

exhaust valve timing “Miller cycle” timing peak cylinder 

temperature yes yes 

5 Conversation with Michael Samulski of EPA, May 2007. 

6

 Melvin Ingalls and Steven Fritz, “Assessment of Emission Control Technologies for EPA Category 3 Commercial 

Marine Diesel Engines,” Southwest Research Institute Report, September 2001. 

ICF International 2-3 U.S. Environmental Protection Agency
 

EPA Contract EP-C-06-094, WA 2-08 April 20099
 
 

Table 2-2. Average Engine Characteristics Used in this Study 

Engine Type Medium-Speed Low-Speed 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12

Liters/cylinder 35 65 95 380 650 1400

Engine Speed (rpm) 650 550 500 130 110 100 

BSFC (g/kWh) 210 195 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

2.1.1. Low-Speed Engines 

Low-speed engines are usually two-stroke engines with large displacements up to 2000 

L/cylinder and are used for propulsion on bulk carriers, container ships, larger tankers, general 

cargo and roll-on/roll-off ships. They are typically turbo-charged with aftercooling and have four 

exhaust valves per cylinder. Scavenge air enters the cylinder through a series of intake ports 

arranged around the bottom of the cylinder. Intake is controlled by the piston as it uncovers or 

covers the intake ports. Fuel injection is typically mechanical with 3 injectors per cylinder. They 

typically have 4 to 20 cylinders. 

2.1.2. Medium-Speed Engines 

Medium-speed engines are usually four-stroke engines with significantly smaller cylinder 

displacement (30 to 200 L/ cylinder) than low-speed engines. They are typically used as 

propulsion engines on smaller tankers, general cargo, roll-on/roll-off ships, ferries, cruise ships, 

and as auxiliary engines on large ships for power generation or refrigeration. They are 

commonly turbo-charged and aftercooled, have two intake and two exhaust valves per cylinder 

and are mechanically injected with one injector per cylinder. They typically have 6 to 18 

cylinders. 

2.1.3. Typical Ship Characteristics 

In order to better understand various ship types as they approach U.S. ports, average ship 

characteristics were determined for each ship type based upon the 2002 Category 3 Marine 

Vessel Port Inventory. 7 This information is used to determine average time per port call as well 

as average auxiliary to propulsion power ratios. 

 ICF International, “Commercial Marine Port Inventory Development – 2002 and 2005 Inventories,” September 

2007. Available at 

http://www.regulations.gov/fdmspublic/ContentViewer?objectId=090000648037139b&disposition=attachment&cont 

entType=pdf 

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EPA Contract EP-C-06-094, WA 2-08 April 20099 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

Table 2-3. Average Ship Characteristics by Ship Type 

Ship Type 

Average 

Propulsion 

Power 

(kW) 

Service 

Speed 

(knots) 

Auxiliary 

Power 

Ratio8 

Average 

Auxiliary 

Power 

(kW) 

2002 

Calls 

Auto Carrier 

Bulk Carrier 

Container 

General Cargo 

Passenger 

Reefer 

RoRo 

Tanker 

11,155 

8,350 

26,211 

6,709 

34,800 

10,060 

11,687 

9,667 

18.7 

14.5 

21.6 

15.2 

20.9 

19.5 

16.8 

14.8 

0.266 

0.222 

0.220 

0.191 

0.278 

0.406 

0.259 

0.211 

2,967 

1,854 

5,747 

1,281 

9,674 

4,084 

3,027 

2,040 

3,306 

9,600 

14,703 

7,391 

3,623 

1,447 

2,137 

13,310 

Average 15,244 17.4 0.227 3,533 55,517 

Average auxiliary engine load factors and average hotelling time by ship type are given in Table 

2-4 for ships calling on U.S. ports in 2002. 

Table 2-4. Average Auxiliary Engine Load Factors and Hotelling Times by Ship Type 

Ship Type 

Auxiliary Load Factors Hotel 

Cruise Transit Maneuver Hotel (hrs)

Auto Carrier 

Bulk Carrier 

Container 

General Cargo 

Passenger 

Reefer 

RoRo 

Tanker 

13% 30% 67% 

17% 27% 45% 

13% 25% 50% 

17% 27% 45% 

80% 80% 80% 

15% 30% 45% 

20% 34% 67% 

13% 27% 45% 

24% 

22% 

17% 

22% 

64% 

30% 

34% 

67% 

45.0 

88.0 

48.0 

88.0 

11.0 

60.0 

45.0 

38.0 

Average 19% 30% 51% 35% 55.5 

2.2. Advanced Technologies 

Technologies that can be used to meet Tier II and Tier III emission levels are discussed in this 

section along with those that would be used to retrofit engines built between 1990 and 1999 to 

meet Tier I emission levels. 

2.2.1. Tier I Retrofit Technologies 

The October 2008 amendments to MARPOL Annex VI include regulations on ships constructed 

on or after January 1, 1990 but prior to January 1, 2000 for marine diesel engines with a per 

cylinder displacement of at least 90 liters and with a power output of over 5,000 kW. Such 

engines must be retrofit and be certified confirming the engine meets Tier I standards. Most 

manufacturers will comply with the regulation by providing retrofit kits which contain modified 

 Ratio of total auxiliary engine power to total propulsion power. These were determined from a survey of 327 ships 

in January 2005 by the California Air Resources Board. 

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EPA Contract EP-C-06-094, WA 2-08 April 20099 

8
 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

fuel injectors and possibly modified injection timing. Approximately all Category 3 ships with 

slow speed diesel engines constructed between 1990 and 1999 have engines with over 90 liters 

per cylinder while approximately 35 percent of Category 3 ships with medium speed diesel 

engines constructed between 1990 and 1999 have engines with over 90 liters per cylinder. 

Retrofit kits for slow speed diesel engines will include low-NOx slide valves. Slide valves have 

zero sac volume so fuel dribbling into the engine cylinder after injection is minimized. This leads 

to lower HC and CO emissions as well as lower PM emissions because any fuel that dribbles 

into the engine cylinder after combustion will tend not to burn completely. In addition, low-NOx 

slide valves have optimized spray patterns which minimize NOx formation. Low-NOx slide 

valves have been shown to reduce NOx from 20 to 25 percent with a 1 to 2 percent fuel 

consumption penalty.9 

Retrofit kits for medium speed engines would likely include injectors modified for low NOx 

performance and injection timing retard. By locating the flame zones closer to metal surfaces 

(cylinder head, piston) NOx can be reduced in medium speed engines.10 Cooling of the flame 

and/or burnt gases by surfaces reduces NOx. Too much cooling, or impingement of unburnt fuel 

on metal surfaces would increase smoke. By changing the spray cone angle, NOx can also be 

reduced. It is expected that NOx optimized nozzles could provide a 20 to 25 percent drop in 

NOx with in a 1 to 2 percent fuel consumption penalty. 

2.2.2. Tier II Technologies 

Most engine manufacturers can reach Tier II levels with engine modifications. Some of the 

older mechanically injected engines will be replaced with common rail fuel injection systems.11 

However, it is estimated that approximately 20 percent of low speed engines and 60 percent of 

medium speed engines may still be mechanically injected. Engine modifications include 

retarded fuel injection timing, higher compression ratios, lower excess air ratios, lower inlet air 

temperatures, better fuel distribution, improved nozzle sac design, and use of Miller cycle 

valving. MAN Diesel estimates a 4 to 6 g/kWh increase in specific oil fuel consumption (SOFC) 

to meet Tier II regulations.11 

2.2.2.1 Fuel Injection Timing 

By injecting later in the engine cycle, maximum cylinder pressure is reduced, thereby lowering 

peak cylinder temperatures and thus NOx production. However, lowering maximum cylinder 

pressure also reduces engine efficiency and increases particulate emissions. In one instance, 

by retarding the injection by 2o crank angle, cylinder pressures were reduced by about 10 bar 

and NOx emissions were reduced by about 10 percent; however, fuel consumption was 

increased by about 1.5 percent.12 Maximum NOx reductions through this method are about 25 

percent, but can be limited by turbocharger speed, because more energy escaping the exhaust 

will provide more energy to the turbocharger, thereby increasing cylinder pressures. 

9 Goldsworthy, L., "Design of Ship Engines for Reduced Emissions of Oxides of Nitrogen," in Engineering a 

Sustainable Future Conference Proceedings. July 2002. Available at 

http://www.amc.edu.au/system/files/shipNOx.pdf 10 Paro, D., "Development of the Sustainable Engine," 23rd CIMAC Congress, 2001. 

11 MAN Diesel, “Exhaust Gas Emission Control Today and Tomorrow,” August 19, 2008,” available at 

http://www.manbw.com/article_009187.html 

12 Geist et al., “Marine Diesel NOx Reduction Technique- A New Sulzer Diesel Ltd Approach,” SAE paper 970321. 

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EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

Retarding fuel injection timing also increases the exhaust temperature. Exhaust valves need to 

be kept below 450°C to prevent excessive damage and short operational life. In many cases, 

exhaust valves are additionally cooled and exhaust valve faces are clad with erosion-resistant 

materials. Higher grade cylinder liners are used to reduce wear. Pistons are also additionally 

cooled with oil jets and clad to prevent hot spots and piston damage. 

2.2.2.2 Higher Compression Ratio 

The effective compression ratio of an engine can be increased by increasing the geometric 

compression ratio by installing piston rod shims, varying the valve timing or by increasing the 

scavenge air pressure. Raising compression ratio generally increases NOx while reducing PM 

and BSFC. When higher compression ratios are used with fuel injection timing retard, the 

compression pressure increase due to combustion is minimized and thereby NOx emissions are 

reduced. Varying valve timing or increasing the scavenge air pressure; however, influence the 

excess air ratio so NOx formation rates are affected as well (see Section 2.2.1.3 below). The 

maximum achievable NOx reductions of 25 percent from fuel injection timing retard can be 

achieved without a fuel consumption penalty if the compression ratio is raised. The maximum 

compression ratio is limited by the structural strength of the engine. Additional strengthening of 

the rods, crankshaft, piston, head, and cylinder liner are sometimes needed to handle the 

additional combustion pressures and temperatures. 

2.2.2.3 Excess Air Ratio 

Oxygen concentration in the fuel/air mixture affects NOx emission formation. Lowering the air 

excess ratio from 2.2 to 1.9 by adjusting the valve timing and compression ratio at the same 

time to keep the effective compression ratio constant can reduce NOx emissions by about 15 

percent and result in a slight reduction in fuel consumption12 Lowering the excess air ratio 

increases the thermal load on the engine, thereby limiting the amount of NOx reduction possible 

from this method. 

2.2.2.4 Inlet Air Temperature 

By lowering the scavenge air temperature, NOx emissions can be decreased. In most engines, 

the scavenge air temperature is limited by the cooling water temperature. However, use of a 

separate circuit aftercooling system (which utilizes an additional heat exchanger for the 

aftercooler) can further reduce the air temperature and provide substantial reductions in NOx 

emissions while providing a reduction in fuel consumption. Some engines already use separate 

circuit aftercooling, while others install the aftercooler prior to the engine cooling circuit, ensuring 

it receives cooler water than the after the engine water jacket. Separate circuit aftercooling 

provides larger benefits than just plumbing the aftercooler first in the engine cooling circuit 

because lower inlet temperatures can be achieved with separate circuit aftercooling. 

2.2.2.5 Fuel Distribution 

Fuel distribution in the cylinder is influenced by intake air swirl, the number of injection nozzles, 

the fuel spray pattern, droplet size and to a lesser degree, injection pressure. The interaction 

between the sprays from individual nozzle holes has a significant impact on NOx. There exists 

an optimum number of nozzle holes for minimum NOx. In addition the angle of the spray cone 

can also affect NOx. By directing the spray near the piston, there is less air entrainment in the 

earlier stages of injection leading to lower NOx emissions. This can also enhance turbulence 

and mixing during the latter stage of combustion which reduces emissions and fuel 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

consumption. NOx reductions of 30 percent have been achieved in some engines, but in most 

cases there is a strong trade-off between NOx reductions and fuel consumption.9 

2.2.2.6 Nozzle Sac Design 

By reducing nozzle sac volume, particulate and hydrocarbon emissions are reduced. The 

nozzle sac is the small volume at the end of the nozzle that can contain trapped fuel after the 

injector valve closes. This fuel tends to dribble into the cylinder later in the cycle and tends to 

result in both hydrocarbon and particulate emissions. By eliminating the sac volume, 

hydrocarbon emissions can be reduced up to 75 percent at full load.13 Most low speed engines 

already use slide valve nozzles to meet Tier I emission levels. Diagrams of nozzle sacs are 

shown in Figure 2-1. 

Figure 2-1. Cross-Sectional diagrams of Different Nozzle Sac Designs 

Source: Man B&W14 

2.2.2.7 Miller Cycle Valving 

By using high pressure turbocharging and closing the intake valve before the piston reaches 

bottom dead center (BDC) during the intake stroke, the entrapped air charge will be expanded 

and reach the pressure of a normal turbocharged engine at BDC, but at a significantly cooler 

temperature due to the expansion. This leads to the bulk cylinder temperature being lower 

13 Ole Grøne and Kjeld Aabo, “How to meet local and international marine emission legislation,” presented to the 

Institute of Marine Engineers in Rotterdam, September 2001 

14 Kjeld Aabo, “Marine Transport Fuels and Emissions,” presented at the Third Nordic-Japan Environmental Conference in 

Nagano, Japan, November 2002. 

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EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

during the entire combustion process, which directly reduces NOx emissions. Miller 

supercharging can reduce NOx by 20% without increasing fuel consumption.9 

2.2.2.8 Common Rail Injection/Electronic Fuel Injection 

The common rail refers to a rail or tube running the length of the engine below the level of the 

cylinder cover. Heated fuel is supplied to the common rail injection system at high pressure, 

ready for injection. Injection occurs under constant fuel pressure via electronic/hydraulic highpressure pumps running on multi-lobe cams. 

One manufacturer’s heavy fuel common rail system is constructed from a series of interconnected accumulators. Each common rail injection pump supplies two accumulators. The 

design can be retrofitted to existing engines by simply removing the current injection pumps and 

replacing them with a common rail delivery pump and an accumulator. Each accumulator is 

connected directly to two injectors and each line contains a flow fuse for safety. A flow control 

valve regulates the rail pressure on each of the rail pumps. The regulation signal to the flow 

control valve comes from the electronic control system. The fuel oil injection timing and duration 

are electronically controlled as well. High pressure engine lubricating oil is used to open the fuel 

injection valve. 

NOx reductions from common rail systems are mostly due to the ability to control the amount 

and rate of fuel injection at low loads as opposed to mechanical injection systems. Mechanical 

systems generally do not have the flexibility to provide the right amount of fuel for all load 

settings. Because the right amount of fuel can be injected at all loads, fuel consumption is 

reduced. Outside of its utility for NOx reductions, this technology also reduces visible smoke 

from unburned excess fuel from cruise ships because it limits over-fueling during maneuvering. 

This technology is currently being demonstrated on a low-speed diesel engine constructed by 

Sulzer, called the Sulzer R-T flex engine. It has been estimated that use of the Sulzer R-T flex 

engine, and its common-rail fuel injection system, can provide 20% lower NOx emissions over 

current Tier I standards. Table 2-5 presents key features and benefits of the Sulzer design.15 A 

diagram of a Wärtsilä common rail system is shown in Figure 2-2.16 

15 Stefan Fankhauser, “World’s first common-rail low-speed engine goes to sea,” Marine News, No. 3-2001, pg 12-15 

16 Wärtsilä Corporation, “Wärtsilä Common Rail – A Super Efficient Fuel Injection System,” February 2007, available at 

http://www.wartsila.com/Wartsila/global/docs/en/about_us/twentyfour7/2_2007/common_rail_injection_system_info 

graphics.pdf 

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Table 2-5. Key Attributes and Benefits to the Sulzer RT-flex Common Rail System 

Key Features System Benefits 

o Precise volumetric control of fuel 

injection, with integrated flow-out 

security 

o Variable injection rate shaping and free 

selection of injection pressure 

o Ideally suited for heavy fuel oil 

o Proven, high-efficiency supply pumps 

o Lower levels of vibration and internal 

forces and moments 

o Steady operation at very low running 

speeds with precise speed regulation 

o Reduced maintenance requirements 

o Full electronic common-rail control with 

integrated monitoring functions 

o Better fuel economy (currently due mainly to 

part-load operation) 

o Easier compliance with the NOx emission 

limit in Annex VI of the MARPOL 73/78 

convention 

o Lower steady running speeds, down to 12 

rpm 

o No visible smoke at any operating speed 

Figure 2-2. Wärtsilä Common Rail Fuel Injection System 

Source: Wärtsilä Corporation15 

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A second manufacturer has installed an electronically controlled cam-less engine using an inhouse developed electronic-hydraulic platform on a 37,500 DWT deep sea chemical carrier.17 

The system allows for electronically controlled fuel injection and exhaust valve actuation which 

permit individual and continuous adjustment of the timing for each cylinder. Parts that are 

removed from the mechanical system include the chain drive for camshaft, camshaft with fuel 

cams, exhaust cams and indicator cams, fuel pump actuating gear, including roller guides and 

reversing mechanism, conventional fuel injection pumps, exhaust valve actuating gear and roller 

guides, engine driven starting air distributor, electronic governor with actuator, regulating shaft, 

mechanical engine driven cylinder lubricators, and engine side control console. The items 

added to the engine include a hydraulic power supply, hydraulic cylinder unit with electronic fuel 

injection and electronic exhaust valve activation, electronic alpha cylinder lubricator, 

electronically controlled starting valve, local control panel, control system with governor, and 

condition monitoring system. Two electronic control units are used to control the system with 

one being a backup for the first. The manufacturer claims that the electronic version of the 

engine was very easy to adjust to the prescribed setting values and was able to keep the very 

satisfactory setting values without further adjustments since the vessel's sea trials in November 

of 2000. 

A third manufacturer has further developed mechanically-actuated electronically-controlled unit 

injectors and hydraulically actuated electronically-controlled unit injectors to provide the flexible 

fuel injection characteristics needed to optimize engine performance and emissions.18 The 

manufacturer states that the design approach in both injector concepts is to utilize a Direct 

Operated Check (DOC) to precisely control the pressure, timing and delivery of fuel. The DOC 

is applicable to electronic unit injector or unit pump configurations with either mechanical or 

hydraulic actuation of the pressurizing units. The manufacturer has claimed the technology 

eliminates spray distortion and minimizes parasitic losses which may be seen in common rail 

fuel systems. The manufacturer includes discussion on closed loop NOx control in the 

reference paper. They state that ultra fast NOx sensors are a key part to closed-loop control of 

NOx emissions. The sensors provide the benefits of minimized engine to engine variations, 

minimized cylinder to cylinder variations and improved transient response with reduced 

emission and reduced operational costs. 

2.2.3. Tier III Technologies 

Tier III emission levels will require large reductions in NOx and SOx emissions. Most engine 

manufacturers believe they will use SCR in combination with lower sulfur marine diesel oils 

(MDO) or marine gas oils (MGO) to meet Tier III standards. However, other NOx reduction 

techniques include introduction of water into the combustion chamber either through fumigation, 

fuel emulsions or direct water injection and exhaust gas recirculation. . In fact, Viking Line 

produced simillar NOx reductions to SCR using a HAM system as shown in Figure 2-3.19 While 

SCR outperformed the HAM system on all five ships, the reductions were close. With EGR and 

a HAM system, NOx reductions approaching those for SCR could be achieved. 

17 Sorensen,Per andPedersen, Peter, "The Intelligent Engine Design Status and Service Experience," International 

Council on Combustion Engines, CIMAC Congress 2001 

18 Moncelle, M.E., "Fuel Injection System & Control Integration," International Council on Combustion Engines, 

CIMAC Congress 2001. 19 Presentation of Ulf Hagstrom, Marine Superintendent, Technical sector, Viking Line Apb, ”Humid Air Motor (HAM) 

and Selective Catalytic Reduction (SCR) Viking Line,” at Swedish Maritime Administration Symposium/Workshop 

on Air Pollution from Ships (May 24-26, 2005) 

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Figure 2-3. Comparison between SCR and HAM 

Other techniques to reduce emissions will include compound or two-stage turbocharging as well 

as electronic valving to enhance performance and emission reductions. To meet low SOx 

requirements, shipping fleets will either use sea water scrubbers or fuel switching to lower sulfur 

fuels or run full time on lower sulfur fuels. 

2.2.3.1 Engine Modifications 

Engine modifications to meet Tier III emission levels will most likely include a higher percentage 

of common rail fuel injection systems coupled with the use of two-stage turbocharging and 

electronic valving. Engine manufacturers estimate that practically all low speed engines and 80 

percent of medium speed engines will use common rail fuel injection. Two stage turbocharging 

will probably be installed on at least 70 percent of all engines produced to meet Tier III emission 

levels. Electronically (hydraulically) actuated intake and exhaust valves for medium speed 

engines and electronically actuated exhaust valves for low speed engines are necessary to 

accommodate two-stage turbocharging. 

Two-stage turbocharging is set up in various fashions. The most popular set up is to use one 

smaller and one larger turbo. The larger turbo's compressor stage blows into the smaller one's 

compressor stage. The exhaust is set up the other way round: it first enters the turbine of the 

smaller turbo, and then the turbine of the larger turbo. Two-stage turbocharging systems were 

shown to improve considerably the performance of four-stroke engines, showing potentials for 

reducing NOX emissions by up to 50 percent at certain load ranges together with some savings 

in fuel consumption. Good part-load performance was ensured by using a variable inlet valve 

closure (VIC) system which enables the Miller effect to be varied according to engine mean 

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effective pressure (BMEP).20 Electronically actuated valves allow variable intake and exhaust 

valve opening and closing which enhances the Miller effect. 

2.2.3.2 Fumigation 

There are currently three types of fumigation systems, namely the Humid Air Motor (HAM), the 

Scavenged Air Moisturizing (SAM) system and the Wetpac H. 

The HAM process was developed by Munters Europe AB, and has undergone trials for 4000 

hours on the MS Mariella in the Viking Line. The HAM system uses heated charge air enriched 

with evaporated seawater to reduce NOx emissions during the combustion process. The HAM 

system is used to replace the conventional engine air intercooler. Since it uses engine heat to 

heat the seawater, additional boiler capacity may be needed for other ship needs. 

The central part of the HAM system is a special humidification unit, which is effectively a heat 

exchanger. This must be mounted very near the engine. Other equipment include a circulation 

pump and filter, a heat exchanger (to heat the incoming water), a “bleed-off” system (to control 

the contents of salt and minerals in the water) and a water tank as shown in Figure 2-3. 

Figure 2-4. HAM System 

Source: Viking Line19 

Water, which has already been heated by the engine cooling system, is additionally heated and 

vaporized using hot air from the turbocharger. This humidified charge air is directed into the 

combustion chamber after filtration for debris. The system has been reported to reduce NOx by 

70-80% with water to fuel ratios of 2.8 at normal operating speeds and loads. 21 While MAN 

B&W has tested HAM units on smaller engines typically on ferries, no tests to date have been 

done on engines the size used on container or bulk carrier vessels. 

In contrast to SCR, no warm-up time is necessary with HAM and NOx reduction commences 

more or less once the motor is engaged. As a precaution to minimize possible corrosion in the 

20 Wartsila Corporation, “Joint diesel research project completed,” Trade & Technical Press release, 6 September 

2007 available at http://www.wartsila.com/ch,en,press,0,tradepressrelease,3D5201D4-5D37-4E26-B7E8­

D4E6F592CE6A,5B771063-161A-4942-810E-5329B81B3565,,.htm 21 Peter Mullins, “The H.A.M. System Approach to Reducing NOx,” Diesel & Gas Turbine Worldwide, November 

2000. 

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humidification unit, it is advised that the water flow is turned off around 15 minutes before 

engine shut down to dry out the exhaust tower. Although MS Mariella operates using a lower 

sulfur heavy fuel oil (IF 220), an additional claimed advantage over SCR is that HAM is suitable 

for residual oils with higher sulfur contents of up to 4.5 percent.22 

The SAM system is being developed by MAN B&W and has been tested on the M/V Mignon of 

the Wallenius-Wilhelmsen Lines. The SAM installed on a B&W 8S60MC engine on the M/V 

Mignon has a sea water injection stage, where a surplus of sea water is injected for saturation 

and cooling of the hot air from the compressor. The sea water (SW) stage provides nearly 100% 

humidification of the scavenge air and supplies all of the water for humidification.11 The SAM 

system is shown in Figure 2-4. The SAM components in the compressor air cooler arrangement 

(i.e. SW spray, transition piece, S-bend and inlet box for the fresh water stages [FW1 and FW2]) 

are manufactured in austenitic stainless 254SMO because of its excellent resistance against 

corrosion from salt water. 

Figure 2-5. SAM System 

Source: MAN B&W11 

The Wetpac H is developed by Wärtsilä. The principle of Wetpac H technology is to introduce 

pressurized water into the combustion process to reduce NOx formation. The pressurized water 

is added to the intake air after the turbocharger compressor. Due to the high temperature of the 

compressed air, the water evaporates immediately and enters the cylinders as steam, thus 

lowering the combustion temperatures and the formation of NOx. Wetpac H technology has so 

far been developed for the Wärtsilä 20, 32 and 46 engine types, and the first pilot installation 

was commissioned in 2003. The anticipated NOx reduction is up to 50%, and the water 

consumption is expected to be about two times the fuel oil consumption. The Wetpac H system 

is shown in Figure 2-5. 

22 Entec UK Ltd, “Service Contract on Ship Emissions: Assignment, Abatement and Market Based Instruments – 

Task 2b – NOx Abatement,” August 2005 available at http://ec.europa.eu/environment/air/pdf/task2_nox.pdf 

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Figure 2-6. Wetpac H System

 Source: Wärtsilä Corporation23 

2.2.3.3 Fuel Emulsification 

Another method of introducing water into the combustion chamber to reduce NOx production is 

through water-in-fuel emulsions. MAN B&W has been testing water-in-fuel emulsions since the 

early 1980s. Formation of the emulsion is achieved within the standard fuel module, which has 

to be slightly modified. Given that a fuel injector delivers a fixed volume of fuel for a particular 

power output, the addition of water increases the volume that must be injected. This fact 

requires that the injector assembly – specifically the atomizer design, must be adapted to the 

increased injection volume. Fuel emulsification can be used on either mechanical or electronic 

injection system. A schematic of a pressurized water emulsion system is shown in Figure 2-6. 

23 German Weisser, “Emission Reduction Solutions for Marine Vessels – Wärtsilä Perspective,” presented at the Clean Ships – 

Advanced Technology for Clean Air Conference, February 2007. Available at 

http://www.cleanshipsconference.com/pdfs/Weisser.pdf 

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Figure 2-7. Pressurized Fuel Emulsification System 

Source: MAN B&W11 

Water emulsion systems require modification to the fuel pump, camshaft and control system to 

handle additional water for full load operation. A pressurized system is also needed to avoid 

cavitation and boiling off in the low pressure part of the fuel system. In addition, a water dosage 

system and homogenizer is needed. Water’s higher viscosity requires the mixture be heated 

further by about 20°C to properly flow through the injection system. In addition the fuel pressure 

needs to be raised to keep the water from boiling. 

MAN B&W reports no effect on specific fuel consumption. They estimate that with 10% 

water/fuel ratio, a NOx reduction of 10% can be achieved but the maximum reduction is about 

50%.11 However, in practice NOx reduction is limited by the maximum delivery capacity of the 

fuel injection pumps. At low ratings or at low load, higher NOx reductions can be achieved. In 

addition, water emulsification in combination with an electronically controlled engine offers the 

following additional flexibility advantages: 

o	 Optimal injection rate shaping can be achieved both without and with any water content. 

o	 ‘‘Free rate shaping’’ allows the use of large water amounts even at low engine load as 

pre-injection can be used to compensate for ignition delay. 

Water-in-fuel emulsification is currently being tested on an 11K90MC engine installed on an 

APL container vessel. The test is expected to be finalized at the beginning of 2009.11 

2.2.3.4 Direct Water Injection 

Direct Water Injection (DWI) is another method to reduce cycle temperatures and therefore 

lower NOx emissions. This method has been under development for Sulzer low-speed engines 

since 1993. Unlike other water techniques, DWI enables water to be injected at the right time 

and place to obtain the greatest reductions in NOx emissions. The water is injected into the 

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cylinder using a fully independent, second common rail injection system under electronic 

control. Also in comparison to emulsification, it allows water to be injected into the engine 

without derating the engine and allows the fuel and water to be injected at different times. 

Injection can occur either during the compression stroke or with fuel injection so that injection 

timing can be optimized to both reduce NOx and other emissions without affecting engine 

reliability. Water injection can be turned off or on without affecting fuel injection behavior. NOx 

emissions can be reduced 50% using a 0.7 water/fuel ratio. 24 Water is fed to the cylinder head 

at high pressure (210-400 bar depending on the engine type). High water pressure is generated 

in a high-pressure water pump module. A low-pressure pump is also necessary to ensure a 

sufficiently stable water flow to the high-pressure pump. Water entering the low pressure pump 

needs to be filtered to remove all solid particles. The pumps and filters are built into a module to 

enable easy installation as shown in Figure 2-7. NOx reduction is most efficient from 40% load 

and higher of nominal engine output. 

DWI requires that fresh water be generated onboard the ship and stored. Currently, a 20 to 50 

percent water addition is anticipated, meaning substantial quantities of water must be generated 

and stored. Fresh water generators can be heated using engine cooling water or using steam 

from an exhaust gas economizer. In addition, there must be sufficient tank capacity for the 

water with the necessary handling system. 

Figure 2-8. DWI Unit for Pressurizing Water and injectors 

23 Source: Wärtsilä Corporation25, 

24 H. Schmid and G. Weisser, “Marine Technologies for Reduced Emissions,” Wärtsilä Corporation, April 2005. 

Available at 

http://www.wartsila.com/Wartsila/global/docs/en/ship_power/media_publications/technical_papers/sulzer/marine_te 

chnologies_for_reduced_emissions.pdf 

25 Wärtsilä, “The EnviroEngine Concept,” 2004. 

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Technology Description 

DWI is one of the technologies currently being employed by Wärtsilä, which has provided 

extensive information on the method, as presented in Table 2-6. 

Table 2-6. Benefits and Limitations of Wärtsilä’s DWI Technology 

Key Benefits 

o NOx emissions are reduced by 50-60% 

o NOx emissions when running MDO are 

typically 4-6 g/kWh 

o NOx emissions when running Residual 

Oil are typically 5-7 g/kWh 

o The engine can also be operated without 

water injection, if necessary 

o The engine can be transferred to “nonwater” operational mode at any load 

o In alarm situations, transfer to “non-water” 

mode is automatic and instant 

o Space requirements for the equipment are 

minimal and therefore the system can be 

installed in all installations 

o Investment and operational costs are low 

o Ratio of injected water to injected fuel 

typically 0.4 to 0.7 

o Can be installed while the ship is in 

operation 

System Limitations 

o Cannot be used at its maximum at low loads 

o Increases fuel consumption 

o Clean water supply needed 

2.2.3.5 Exhaust Gas Recirculation 

MAN Diesel originally tested a simplified exhaust gas recirculation (EGR) system which 

consisted of a loop from the exhaust gas receiver that went past the last charge air cooler, but 

connected just before the last water mist catcher on a low speed engine. This was thought to 

prevent fouling of sensitive engine parts due to high particulate and sulfur oxide levels in the 

exhaust from burning residual oil. It was originally thought that cleaning the exhaust was 

necessary to prevent fouling of the air cooler and receiver components. The system had two 

water injection stages with a simple water separator unit after both. The tests showed a 

substantial NOx reduction but confirmed that the exhaust gas could not be cleaned sufficiently 

before entering the air cooler and scavenge air system. More recently, MAN diesel tested EGR 

with a scrubber and water treatment, obtaining a 70 percent reduction in NOx emissions with a 

relatively small increase in brake specific fuel consumption (BSFC).11 MAN diesel used an 

EcoSilencer® to clean the exhaust gas before reintroducing it into the air cooler and scavenge 

air. The scrubber removed 90 percent of the PM emissions and 70 percent of the SOx with no 

water carry over. The EGR scrubber is shown in Figure 2-8. 

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Figure 2-9. MAN Diesel EGR Scrubber 

Source: MAN B&W11 

2.2.3.6 Selective Catalytic Reduction 

The Selective Catalytic Reduction (SCR) process involves injecting a reagent, such as ammonia 

or urea, into an exhaust flow, upstream of a reactor, to reduce NOx compounds into nitrogen 

and water. The system effectiveness is strongly dependent on the type of catalyst and the 

reactor temperature which generally needs to be from 210oC to 500oC.26 For 4-stroke engines 

with relatively high exhaust temperatures, the reactor unit can be placed downstream from the 

exhaust manifold as shown in Figure 2-9. Main system components are: an SCR reactor, 

aqueous urea injection/dosing, and monitoring/control systems. The SCR system does require 

storage of urea solution on-board in a separate tank. 

In order to control ammonia slip (urea that is not used in the SCR unit, escaping to the exhaust) 

and reach optimal operation of the SCR unit, temperatures, pressures, and other parameters 

need to be carefully monitored and controlled. In addition, the urea injected into the exhaust 

stream before the SCR reactor, needs to be well mixed with the exhaust gases before entering 

the reactor for optimal performance. 

26 The minimum temperature of 210°C requires 1000 ppm sulfur fuel. The minimum rises to approximately 300°C when 2.5 

percent sulfur residual oil is used. While the SCR reactor can handle temperatures of 500°C, engine manufacturers tend to 

limit exhaust temperatures to 450°C to protect valves from fouling due to vanadium and sodium present in residual oil. 

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Figure 2-10. Example of Urea SCR System for a 4-stroke engine with the reactor placed 

downstream of turbocharger

 Source: Wärtsilä Corporation27 

Low-speed and large medium-speed engines operate at relatively low exhaust temperatures 

such that the SCR reactors need to be located between the turbocharger inlet and the engine’s 

exhaust manifold in order to get enough heat (see figure below). 

27 http://www.wartsila.com/Wartsila/global/docs/en/service/Leaflets/enviro/COMPACT_SCR.pdf 

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Figure 2-11. Urea SCR system with Reactor Installation before Turbocharger

 Source: Wärtsilä Corporation23 

The urea SCR systems have successfully been used for large stationary source applications 

where loads are fairly constant. In the marine sector, a majority of the installations of SCR 

technology have taken place on smaller four-stroke engines as opposed to the larger two-stroke 

main engines. There are more than 300 marine SCR systems currently in operation developed 

by Argillon, Wärtsilä, Munters, and other companies. In certain marine engine applications, this 

technology can be used in conjunction with a diesel oxidation catalyst to reduce PM emissions. 

There are reports that a properly designed Urea SCR system can reduce NOx emission by 

more than 98% but this is most likely with significantly lower sulfur fuel. Clean Diesel 

Technologies is one company that markets diesel exhaust aftertreatment technologies for 

various applications including marine and claims that typical NOx conversion efficiency is 

between 70 to 90 percent in reactors that maintain temperatures above 320°C28. Argillon 

consistently reports that their best designs can maintain 95 percent efficiency under most 

conditions.29 Most companies suggest that for analysis purposes 90 to 95 percent NOx 

reduction efficiency can be assumed for properly designed systems. 

In addition to operating temperature sensitivity to high sulfur fuels, high sulfur fuels can also 

create large amounts of SOx which keep urea SCR reactors from operating effectively. Sulfur 

oxides can react with oxygen in the exhaust and form sulfuric acid, which can cause corrosion 

and reduce SCR system life. Also high levels of SOx can interfere with the NOx reduction 

reaction decreasing the SCR system effectiveness. In addition if the exhaust temperature is too 

low, ammonia salts will form on the SCR unit which can essentially plug the reactor. This is 

more a problem with low speed engines than medium speed engines. In those cases, the SCR 

unit will be shut off to prevent ammonia salt formation. 

28 Clean Diesel Technologies corporate website http://www.cdti.com/content/technology/overview.htm 29 Argillon Website, http://www.argillon.com/business-segments/systems/industrial-applications/overview.html 

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2.2.3.7 Sea Water Scrubbers 

Seawater scrubbing technology is designed to reduce SOx and PM emissions from large marine 

and stationary engines situated near a shoreline. The technology uses wet Flue Gas 

Desulphurization, which is the mixing of hot exhaust flue gases with seawater. Seawater is 

alkaline by nature and rich in calcium sulfates which react well with acidic gases like SO2. The 

reaction forms products which are soluble in water and can be discharged overboard in open 

sea operation. For areas where acidic water discharge is a concern, for example port operation, 

the water from a scrubber is diluted with additional seawater before discharge. 

Figure 2-11 provides a simplified schematic of one seawater scrubber design (by MES). These 

systems are very effective at removing SO2 and the direct sulfate component of the exhaust 

PM. Carbonaceous PM in the engine exhaust is removed through impaction; however, much of 

the carbonaceous PM can be trapped in bubbles and may pass through the scrubber, so PM 

treatment efficiency in the seawater scrubber is highly dependent on the design. The captured 

PM can be removed from the stream exiting the scrubber by filtering and is kept in a settling or 

sludge tank for later disposal. 

Figure 2-12. Seawater Scrubbing System with EcoSilencer® for a “Super Yacht” design for 

engines up to 3.5MW

 Source: Marine Exhaust Solutions, Inc.30 

While the scrubber design parameters such as reactor volume will greatly impact its 

effectiveness, the technology efficiency also depends on the SOx concentration in engine 

exhaust, as well as factors such as seawater temperature or salinity. Marine Exhaust 

30 Hamid Hefazi and Hamid R. Rahai, Center for Energy and Environmental Research and Services, California State 

University, Long Beach, “Emissions Control Technologies for Ocean Going Vessels,” Final Report Submitted to 

State of California ARB, June 2008 

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Solutions31, a Canadian company, for example, claims that for engines burning up to 4.5 

percent sulfur fuel, their EcoSilencer® system will reduce SO2 emissions by up to 90 percent 

(higher with lower sulfur fuel). It will also eliminate up to 90 percent of visible PM (up to 50 

percent by mass), as well as reduce approximately 3 to 5 percent NOx. The company claims 

that the system can be used in wide range of engines from 0.1 to 100MW. 

Various scrubber designs are marketed by different companies. There are industry claims that 

properly designed systems are capable of nearly complete removal of sulfur compounds from 

engine exhaust, as well as up to 80 percent PM removal.32 

The seawater scrubbing systems do result in a fuel economy penalty in terms of pumping power 

since large amounts of wash water needs to be circulated through the system. Industry 

estimates of the penalty vary but generally fall within 1 to 3% range depending on operating and 

fuel quality conditions. 

2.3. Fuel Switching 

Switching from a heavy fuel oil (HFO) with an average sulfur content of 2.7 percent to a distillate 

fuel, such as marine distillate oil (MDO) or marine gas oil (MGO) with a sulfur content of 0.1 

percent, either permanently or temporarily, can provide significant SOx and PM reductions. 

However in some cases, vessel modifications may be necessary to achieve this, as it means 

either migrating from the unifuel model or use of the more expensive distilled fuel all the time. 

The following section discusses the systems needed to deliver these fuels. The next section 

discusses technical obstacles of fuel switching. The final section discusses modifications 

needed for fuel switching. 

2.3.1. Vessel fuel systems 

Some current marine vessels are powered by low-speed, 2-stroke, marine diesel engines, 

operating in a unifuel mode on heavy fuel oil.33 Unifuel refers to operating essentially all 

engines on the same fuel type – typically HFO34. Note that, in this system, both main and 

auxiliaries are powered by HFO but relatively small amounts of lighter distillate oil are also 

carried for long term shutdown and emergency use.35 Prior to long term shutdown, the engines 

are operated on distillate fuel to purge the HFO from the fuel system. 

HFO contains contaminants and other residual fuel components that must be treated, purified, 

and/or removed and heated to obtain appropriate viscosity onboard before injection into a 

compression ignition engine. Although, generally heavier fuels require more complex fuel 

treatment systems, all systems prevent heavy fuel oils from solidifying in the fuel system, 

31 Marine Exhaust Solutions, Inc. Corporate website http://www.marineexhaustsolutions.com/ 

32 Krystallon, “Sea Water Scrubbing, Facts and Fantasy,” Presentation at Clean Ships Conference, Sand Diego, CA, 

February 9, 2007. 33 Global Trade and Fuels Assessment “Future Trends and Effects of Requiring Clean Fuels in the Marine Sector,” 

Prepared for EPA by RTI International, EPA420-R-08-021, November 2008, available at: 

http://www.epa.gov/oms/regs/nonroad/marine/ci/420r08021.pdf. This report, in turn, is based largely on the Fuel 

Switching presentations to the California ARB, 7/27/08, available at 

http://www.arb.ca.gov/ports/marinevess/presentations.htm. First order references are provided where appropriate. 34 Also referred to as residual oil (RO). Intermediate fuel oil (IFO) is used commonly. 35 Keith Michel, Herbert Engineering Corp., “California Maritime Technical California Maritime Technical Working 

Group Focus on Fuel Switching: Fuel Oil Systems,” July 24, 2007, available at 

http://www.arb.ca.gov/ports/marinevess/presentations/072407/072407herpres.pdf. 

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improve operational efficiency, and maintain the fuel circulation, injection, and combustion 

systems. These systems consist of storage and settling tanks, filters, and purifiers. 

Fuel is transported from heated bunker tanks to the settling tank by transfer pumps. Settling 

tanks hold enough fuel for approximately 2 days of travel and have coils to heat the fuel, if 

heating is not maintained, the fuel will become too viscous to pump. In the settling tanks, heavy 

fuel solids settle to the bottom while fuel to be burned is drawn from the top of the tank. Fuel is 

then pumped from the settling tank through a pre-heater and into one or more centrifugal 

separators by feed pumps. This fuel is then pumped to the day tank, where approximately one 

day’s reserve of pre-treated and cleaned fuel is maintained at an appropriate temperature to 

maintain fuel viscosity for use in the engine. The engine fuel supply system then draws fuel 

beyond that necessary for combustion from the day tank to the injection system and circulates 

the additional fuel back to the day tank to prevent solidification throughout the supply system. 

Sets of supply and circulating pumps pressurize the system and transfer fuel from the day tank, 

the final engine fuel filter, and injectors while a pre-heater and viscosity meter maintain fuel 

viscosity throughout the fuel system. Figure 2-12 shows a typical shipboard fuel delivery 

system. Figure 2-13 shows a fuel system as a layout onboard the vessel. 

Figure 2-13. Typical Shipboard Unifuel Delivery System

 Source: RTI International33 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

Figure 2-14. Typical Fuel Tank and Delivery Systems 

Containership Tanker 

Source: Herbert Engineering Corp36 

2.3.2. Potential vessel modifications associated with fuel switching 

Technical concerns regarding use of low-sulfur distillate fuels in Category 3 vessel engines 

relate to either steady-state operation on distillate fuels or the process of switching fuels. 

Steady-state distillate fuel use may raise issues of cylinder lubricants and feed rates and fuel 

viscosity and temperature control. Low-speed, 2-stroke engines inject lubricating oil into the fuel 

prior to combustion, potentially requiring separate fuel-feed systems to implement fuel switching 

so that the proper oil is used with the fuel in use. Cylinder lubricating oils contain alkaline 

additives to counteract the acidity caused by sulfur oxides and must be mated appropriately to 

the sulfur content of the fuel used to control the deposition of acids in the cylinders and reduce 

wear. Wärtsilä recommends use of 70 base number (BN) cylinder oil when using fuels with 1.5 

percent or more sulfur and 40BN oil for fuels with lower sulfur levels.37 During periods of fuel 

switching, the BN to sulfur ratio (BN/S) can be out of balance. While unbalanced BN/S ratios 

cause excess engine wear, it is believed that changing lube oil is only necessary if the engines 

are to operate on fuel that is 1 percent sulfur or less for more than one week.38 For longer 

periods, ships may require two cylinder lubricating oil systems. However, there is an oil that has 

36 Herbert Engineering Corp., http://www.arb.ca.gov/ports/marinevess/presentations/072407/072407herpres.pdf 37 Wärtsilä Switzerland Ltd, LOW SULPHUR GUIDELINES: Guidelines for design, modification and operation of new 

buildings and existing ships to comply with future legislation related to low sulphur content in the fuel, Updated: 9th 

January, 2006. Available at: 

http://www.wartsila.com/Wartsila/global//docs/en/ship_power/media_publications/technical_papers/low_sulphur_gu 

idelines.pdf. 38 MAN B&W, Operation on Low-Sulphur Fuels Two-Stroke Engines, available at: 

http://www.manbw.com/article_005271.html. 

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Technology Description 

been recently developed for use with distillate or residual, so this might not be the case 

anymore. 

In addition to BN/S matching, long term use of distillate fuels must consider viscosity matches 

between the fuel and the injection system design, as MDO and MGO are significantly less 

viscous than HFO. Although use of low viscosity fuels in medium speed, 4-stroke engines is 

generally not a concern, severe cases may lead to damaged fuel injection equipment and power 

loss. For low-speed, 2-stroke engines viscosity effects are typically minor, but may be affiliated 

with failed fuel treatment system pumps. Both cases may be mitigated by installation and use of 

a fuel cooler, associated piping, and viscosity meters to the fuel treatment system if fuel 

switching is done on a frequent basis. 

Although all the above mentioned concerns are legitimate, it should be noted that in its 

presentation to ARB, Maersk39 illustrated that all its vessels switch both main and auxiliary 

engines to MDO with less than 0.2 percent sulfur within 24 nautical miles of their California 

destination port for main engines and within 24 nautical miles of the California border for 

auxiliary engines. They have noted no problems to date on their vessels from this program. 

The Maersk study included 78 vessels and 298 switches consuming 23.9 MT of MDO per switch 

from April 2006 to April or May 2007. The resulting total emissions reduction has been 

calculated at 800 tons per year, including a 95 percent SOx, 87 percent PM, and 12 percent 

NOx reduction (which includes low-NOx auxiliary mode). These reductions are greater than 

anticipated by the program. In the Maersk study, all vessels used separate service tanks for 

high- and low-sulfur fuels (DMA and DMB, with DMX for lifeboat engines and emergency 

generator use) to minimize compatibility issues. Also, as all fuel switching in this program is 

considered short term, they made no cylinder lube oil BN change. Maersk noted that fuel 

switching is considered “normal engineering practice” and provides no special training. 

Some ships may not have sufficient onboard storage capacity to accommodate temporary fuel 

switching since the minimum space practical is devoted to fuel and machinery to maximize 

cargo and, of the space devoted to fuel, a minimal amount is provided for distillate oil tanks on 

unifuel ships. Some dual fuel ships have two fuel oil tank systems—one for residual and one for 

lower sulfur distillate oil. This arrangement may be preferred for fuel switching, since it avoids 

many issues with using dissimilar fuels in the same fuel system while still meeting lower sulfur 

requirements. The common arrangement is for one HFO tank system with multiple HFO tanks 

and associated fuel system and another distillate oil system with one or more MDO or MGO 

storage tanks and a corresponding day tank. 

At their presentation to ARB, Herbert Engineering36 surveyed a range of vessels and their ability 

to switch fuels. They found that, for tanker ships varying from a 50,000 DWT Panamax to a 

300,000 DWT VLCC (Very Large Crude Carrier) vessels, while the HFO capacity and number of 

tanks and ancillary system components varied, the total capacity for distillate fuels remained at 

one settling and one service tank of varying volume with sufficient capacity for between 3.3 and 

3.6 days operating range using distillate fuels in both main and auxiliary engines and in at-sea 

cruising mode with a 15 percent reserve. Typical containerships profiled ranged from a 2,500 

TEU Feedership to a 9,000 TEU Post-Panamax containership. All cases have one storage tank 

and one service tank for distillate fuels except the largest containership, which had two storage 

tanks and one distillate service tank. Again, while total distillate storage volumes varied, the at39 Maersk Pilot Fuel Switch Initiative, A.P. Moller-Maersk Group, Regulatory Affairs Technical Organisation, 26 July 

2007, available at http://www.arb.ca.gov/ports/marinevess/presentations/072407/072407maepres.pdf. 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

sea cruising range using distillate fuels in both the main and auxiliary systems varied from 1.7 to 

2.6 days. This study concluded that existing distillate oil tank capacities should be sufficient to 

accommodate main and auxiliary engine operation in SECAs. Typical onboard storage volumes 

and number of tanks by fuel type are shown in Table 2-7. 

Table 2-7. Typical on-board storage for heavy fuel oil and distillate fuels by vessel type 

Ship Type/Size 

Tank 

Description 

Volume 

(m3

) 

Tank 

Description 

Volume 

(m3

) 

Container Vessels 

2500 TEU Feedership 

6 HFO Storage 

+1 Settling 

+1 Storage 

3,200 

1 DO Storage 

+1 Service 300 

4000 TEU Panamax Containership 

8 HFO Storage 

+1 Settling 

+1 Storage 

7,000 

1 DO Storage 

+1 Service 350 

6000 TEU Post-Panamax Containership 

10 HFO Storage 

+2 Settling 

+1 Storage 

8,000 

1 DO Storage 

+1 Service 400 

9000 TEU Post-Panamax Containership 

12 HFO Storage 

+2 Settling 

+2 Storage 

10,000 

2 DO Storage 

+1 Service 800 

Tanker Vessels 

50,000 DWT Panamax Tanker 

2 HFO Storage 

+1 Settling 

+1 Storage 

1,500 

1 DO Storage 

+1 Service 150 

110,000 DWT Aframax Tanker 

4 HFO Storage 

+1 Settling 

+1 Storage 

3,000 

1 DO Storage 

+1 Service 250 

160,000 DWT Suezmax Tanker 

4 HFO Storage 

+1 Settling 

+1 Storage 

4,000 

1 DO Storage 

+1 Service 350 

300,000 DWT VLCC 

4 HFO Storage 

+2 Settling 

+1 Storage 

5,500 

1 DO Storage 

+1 Service 450 

Source: Herbert Engineering Corp. 36 

Fuel use for a typical call for an average container ship and an average tanker are shown in 

Table 2-8 as a function of ECA distance from shore. Assuming the typical container ship is a 

4000 TEU Panamax and the typical tanker is a 110,000 DWT Aframax, current fuel storage of 

distillate fuel is 343 metric tonnes and 245 metric tonnes respectively based upon a MGO fuel 

density of 980 kg/m3

. Thus even if the ECA is set at 200 nautical miles, a typical ship can make 

three to four calls into and out of a port before needing to refuel with existing distillate tanks. It 

should be noted that the fuel amounts in Table 2-8 represent average vessels, therefore, some 

vessels may require additional capacity to accomplish fuel switching. 

Table 2-8. Fuel Use per Call for Various ECA Distances (Metric Tonnes) 

ECA 

Distance Container Tanker 

25 25.10 19.98 

50 35.31 25.46 

100 55.74 36.44 

200 96.59 58.40 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

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If a new or segregated tank is desired, ancillary equipment such as pumps, piping, vents, filing 

pipes, gauges, and access would be required, as well as tank testing.40 In addition, fuel 

processing systems include settling tanks, filters, and centrifuges may also be necessary. While 

some vessel operators may be able to use their existing processing systems, other operators 

have reported that they will need to add to these systems, along with increased fuel capacity or 

other modifications.41 

Also, should full-time switching from the use of high- to low-sulfur fuels be implemented, the 

Herbert Engineering study concluded that existing engines and fuel oil systems are suitable for 

continuous operation on distillate fuels, although will require use of lubricating oil with a different 

BN. 

2.3.3. Modifications for fuel switching 

In its March 2008 presentation,42 ARB documented results from its 2006 vessel survey. ARB’s 

results showed that approximately 22 percent of vessels surveyed needed some modifications 

to adequately perform main engine fuel switching, but the modifications needed and vessels 

requiring the modifications varied both with distance and vessel type. For main engine fuel 

switching, the required modifications included: 

o Fuel tanks 

o Cylinder lube oil systems 

o Fuel valves 

o Fuel piping and pumps 

o Engine fuel pumps 

o Fuel injectors 

The ARB survey also found that 94 percent of vessels could participate in an auxiliary engineonly fuel switching program without any modifications. Of those that did require modifications, 

the required retrofits included the following: 

o Fuel oil system 

o Fuel tanks and lines 

o Fuel injection/oil pump modifications 

o Fuel oil micronizer 

o Storage tanks 

o Diesel fuel cooler 

o Change lube oil BN and add cooling lines for fuel oil pumps 

40 Entec UK Limited. Quantification of Emissions from Ships Associated with Ship Movements between Ports in the 

European Community, July 2002, pps. 86-87. 

41 Air Resources Board, “Fuel Sulfur And Other Operational Requirements For Ocean-Going Vessels Within 

California Waters And 24 Nautical Miles Of The California Baseline – Initial Statement of Reasoning,” June 2008. 42 2006 Ocean-Going Vessel Survey Results, Cal EPA Air Resources Board, 4th Public Workshop to Discuss 

Development of Regulations for Ocean-going Ship Main Engines and Auxiliary Boilers, March 5, 2008, 

Sacramento, CA. 

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Technology Description 

A small number of survey participants reported the need to modify engine components such as 

fuel pumps, injectors, and nozzles. However, engine manufacturers have stated that, with 

certain caveats, the engines they designed for heavy fuel oil can also operate on MGO without 

these modifications.41 In most cases, the need for fuel injection pumps and nozzles arises from 

the fact that older ship engines used nitrile rubber seals and o-rings which are susceptible to 

shrinking when a hydrogenated lower sulfur distillate fuel is used after running for long periods 

on heavy fuel oils. This causes leaks in both the fuel injector pumps and nozzles. Newer 

pumps and injectors use Viton® o-rings, which are much less susceptible to fuel changes. In 

some cases, replacement of old o-rings and seals will be necessary as an early maintenance 

item to prevent problems. 

2.3.4. Scenarios analyzed and cost methodology 

Three fuel switching cases are analyzed here for costs in Section 3, namely: 

	 Case 0: Vessels meet all requirements of a ECA and require no modifications or 

retrofits (baseline). 

	 Case 1: A newly built vessel requires additional equipment to meet ECA 

requirements over comparable new vessels. 

	 Case 2: Existing vessels will require retrofits to meet ECA requirements. 

In all cases here, we have assumed that both propulsion and auxiliary engines will operate on 

the same distillate fuel when near the coastline for a continuous period of less than 1 week and 

that the distillate fuel will be 0.1 percent sulfur MGO. This analysis does not attempt to 

determine the number of ships that would require these modifications. 

As discussed above, for short periods of operation on lower sulfur fuel for low speed, 2-stroke 

engines, a switch to lower cylinder lube oil TBN is not necessary. We have assumed that within 

the one week period considered here is within that range. Note that this switch is not applicable 

to 4-stroke engines. 

We have based all calculations on the estimate that any retrofit distillate tanks would be 

designed to hold 250 hours of fuel under normal operation. This is larger than is currently 

available on most ships that currently carry distillate fuel as noted in the Herbert Engineering 

presentation (see Table 2-7). In building these tanks, we have assumed that they will be 

composed of cold rolled steel 1 mm thick and double walled. 

Because fuel treatment systems vary by vessel and the fuel switching program will vary with the 

vessel treatment system, characterizing general costs is difficult. However, most ships have 

distillate systems onboard, although fuel switching may require modifications to accommodate 

the distillate usage envisioned here. The system envisioned here is most like MAN B&W’s Fuel 

Oil System No. 1 with one distillate and one heavy fuel oil settling tank, shown by Figure 2-14. 

Here, both HFO and MDO have a dedicated bunkering, settling, centrifuging, and service tank 

system. The distillate and residual systems are independent until fuel supply pressurization, and 

the injection systems are shared. If MGO is used instead, the settling tank and centrifuge might 

not be necessary. 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Technology Description 

Figure 2-15. MAN B&W’s Fuel Oil System No. 1 

MGO
 

(Boiler Support)
 

(Iner ) etce Inert Gas tc.
) 

Service To Gensets

Tank 

(day) If unifuel system 35°C 

MDO Storage Tank (25°C) Centrifuge(s) 

(40°C) 

Service 

Tank 

Bunker Storage Tank 1 (45°C) (day) 

90°C 

HFO Supply HFO Circulating 

Bunker Storage Tank 2 (45°C) pump pump 

Bunker Storage Tank 3 (45°C) Centrifuge(s) 

(95 � 100°C) 

Source: MAN B&W38 

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3. Economic Impact 

3.1. Cost Estimation Methodology 

In order to determine the estimated cost of compliance with potential future emission 

regulations, representative models of low- and medium-speed Category 3 marine diesel engines 

were chosen among several manufacturers’ engine lines and costs were estimated for each. 

No single model’s costs were used to develop the estimates presented in this report. Once cost 

information was developed, cost spreadsheets were shared with engine and emission control 

equipment manufacturers for comment. Presented costs for each technology represent a best 

estimate based upon all the input received. 

Costs for the technologies discussed in Section 2 are presented in this section. These costs 

include hardware costs and fixed costs. Costs for changes in fuel consumption are also 

discussed. All costs represent the incremental costs for engines to meet the proposed emission 

standards. 

Typically, Category 3 engines and emission reduction technologies are built outside the United 

States. All costs have been converted to 2006 U.S. dollars. 

3.1.1. Hardware Cost to Manufacturer 

Component costs were developed for each technology discussed in Section 2. Separate costs 

were derived for each of the various engines shown in Table 2-2. Manufacturer costs of 

components were estimated from various sources including information from marine diesel 

engine manufacturers, and previous work performed by the author of this document.43 Labor 

rates used in this study were taken from Salary.com44 for New Jersey and include a 60 percent 

fringe rate as shown in Table 3-1. 

Table 3-1. Labor Rates 

Labor Category 

Annual 

Salary 60% Fringe 

Annual 

Rate 

Hourly 

Rate 

Design Engineer II $75,000 $45,000 $120,000 $57.69 

Mechanic Technician II $50,000 $30,000 $80,000 $38.46 

Floor Assembler II $31,000 $18,600 $49,600 $23.85 

Hardware costs provided by a supplier other than the engine manufacturer are subject to a 29 

percent mark up, which represents an average supplier mark up of technologies on new engine 

sales.45 

3.1.2. Fixed Cost to Manufacturer 

The fixed costs to the manufacturer consist of the cost of researching, developing and testing a 

new technology. They also include the cost of retooling for the production of new parts. 

Research and development costs reflect the need for manufacturers to focus on adapting 

43 L.Browning and R. Barnitt, “Emission Reduction Technology Costs for Category 3 Marine Diesel Engines,” April 

2002. 

44 http://www.salary.com 45 Jack Faucett Associates, “Update of EPA’s Motor Vehicle Emission Control Equipment Retail Price Equivalent 

(RPE) Calculation Formula,” Report No. JACKFAU-85-322-3, September 1985. 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

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emission controls to specific marine diesel engine applications, with significant engine 

calibration needed to optimize these controls over a large range of ship types and operating 

conditions. 

Each year of research and development has been defined as 1 engineer and 2 technicians plus 

24 engine tests per year at $10,000 per test. Total R&D costs per year are shown in Table 4-1. 

Table 3-2. Annual Research and Development Costs 

1 engineer $120,000 

2 technician $160,000 

40% overhead $168,000 

24 Tests @ $10,000 per test $240,000 

$688,000 

In addition, a $5,000 fee is added for Marine Society approval of the technology. All real costs 

calculated in this report are in 2006 dollars with future costs discounted at 7 percent per annum. 

R&D costs are expected to occur over a three year period ending one year prior to engine 

production. Tooling costs are expected to occur one year prior to engine production. Both R&D 

and tooling costs are expected to be recovered over the first five years of engine sales. Cost of 

money was assumed to be 7 percent per annum for these calculations. The estimated number 

of units per year was supplied by EPA. 

3.1.3. Fuel Economy 

As discussed in Section 2, many of the technologies can lead to either a fuel cost savings or 

cost penalty for the user. An estimate of these changes in fuel consumption is developed in this 

report by using engine characteristics such as brake specific fuel consumption (BSFC) and load 

factors. 

The BSFC used in the analysis is listed in Table 2-2. For an average call, assuming that the 

Emission Control Area (ECA) starts 200 nautical miles (nm) from U.S. shores, average load 

factors for propulsion and auxiliary engines are given in Table 3-3. 

Table 3-3. Average Load Factors 

Mode 

Speed 

(knots) 

One-Way 

Distance 

(nm) 

Time per 

Call 

(Hours) 

Propulsion 

Load Factor 

Auxiliary 

Load 

Factor 

Cruise 17.4 200 23.0 83% 19% 

Transit 12 12 2.0 27% 30% 

Maneuver 5 5 2.0 2% 51% 

Hotel -- -- 55.5 35% 

Total/Average 82.4 73% 31% 

Using the following formula, an estimate of the yearly fuel consumption for a 1% change in fuel 

consumption is determined. Actual fuel use can be scaled from this value using the ratio of 

actual fuel consumption change to the 1% change calculated here. 

Annual Fuel Use = (Avg BSFC) * (Nominal hp) * (Load Factor) * (Annual hr of operation) 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

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3.2. Retrofit Tier I Technology Costs 

The costs for the retrofit kit include new fuel injectors plus 3 months R&D to modify timing. A 

Marine Society approval certificate is also included. As part of the IMO regulations, the retrofit 

kit cannot exceed $375 Special Drawing Rights (SDR)/metric tonne of NOx reduced. The 

currency value of the SDR is determined by summing the values in U.S. dollars, based on 

market exchange rates, of a basket of major currencies (the U.S. dollar, Euro, Japanese yen, 

and pound sterling). The SDR currency value is calculated daily and the valuation basket is 

reviewed and adjusted every five years. Current conversion rates are $1.49129 per SDR. As 

can be seen from Table 3-4, the cost effectiveness of the retrofit kits described above are 

significantly less than the maximum cost allowed in Annex VI. 

Table 3-4. Cost of Retrofit Kits 

Speed Medium Low Low Low 

Engine Power (kW) 18,000 8,500 15,000 48,000 

Cylinders 16 6 8 12 

Liters/cylinder 95 380 650 1400 

Engine Speed (rpm) 500 130 110 100 

Hardware Cost to Engine Manufacturer 

Component Costs 

 Number of Injectors 16 18 24 36 

 Improved Fuel Valves (each) $235 $235 $375 $470 

Total Component Cost $3,760 $4,230 $9,000 $16,920 

Assembly 

 Labor (hours) 120 168 216 312 

 Cost ($23.85/hr) $2,862 $4,006 $5,151 $7,440 

Overhead @ 40% $1,145 $1,602 $2,060 $2,976 

Total Assembly Cost $4,006 $5,609 $7,211 $10,416 

Total Variable Cost $7,766 $9,839 $16,211 $27,336 

Markup @ 29% $2,252 $2,853 $4,701 $7,927 

Total Hardware RPE $10,018 $12,692 $20,912 $35,263 

Fixed Costs 

R&D Costs (0.25 year R&D) $172,000 $172,000 $172,000 $172,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 

Years to recover 5 5 5 5 

Fixed cost/engine $1,233 $1,233 $1,233 $1,233 

Total Costs $11,251 $13,925 $22,145 $36,496 

Cost/kW $0.6 $1.6 $1.5 $0.8 

Estimated Emission Reduction (MT NOx) 638.67 389.92 688.09 2,201.89 

Cost Effectiveness (SDR/MT NOx) $11.8 $23.8 $21.5 $11.1 

For estimated emission reduction, emission reductions are calculated at 11 percent of baseline 

emissions for 6000 hours per year for 5 years with a load factor of 0.768. Baseline NOx 

emission rates are 14 g/kWh for medium speed engines and 18.1 g/kWh for slow speed 

engines. Emission reductions in metric tonnes are thus calculated as follows: 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Slow Speed Engines: 18.1 g/kWh x Power (kW) x 0.768 x 6000 hours/yr x 5 years/1000000 g/metric tonne x 11% 

Medium Speed engines: 14 g/ kWh x Power (kW) x 0.768 x 6000 hours/yr x 5 years/1000000 g/metric tonne x 11% 

3.3. Tier II Technology Costs 

As discussed in Section 2, Tier II technology costs include engine modification costs and 

common rail fuel injection system costs. Engine modification costs to meet proposed Tier II 

emission levels are given in Table 3-5. These costs include modification of fuel injection timing, 

increasing the compression ratio, fuel injection nozzle optimization and Miller cycle effects. 

Retooling costs include cylinder head and piston rod shim modifications to increase 

compression ratios as well as to accommodate different injection nozzles. 

Table 3-5. Differential Costs for Engine Modifications to Meet Tier II Emission Levels 

Engine Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Fixed Costs 

R&D Costs (1 year R&D) $688,000 $688,000 $688,000 $688,000 $688,000 $688,000 

Retooling Costs $500,000 $750,000 $1,000,000 $750,000 $1,000,000 $1,250,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $8,103 $9,734 $11,365 $9,734 $11,365 $12,996 

Total Costs $8,103 $9,734 $11,365 $9,734 $11,365 $12,996 

Cost per kW $1.8 $1.0 $0.6 $1.1 $0.8 $0.3 

Differential costs for new common rail fuel injection engines that replace engines that were 

mechanically injected are given in Table 3-6. Differential costs for common rail fuel injection 

engines that replace engine that were previously electronically controlled are given in Table 3-7. 

Retooling costs include modification of the cylinder head to accommodate common rail fuel 

injection systems. 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

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Table 3-6. Common Rail Fuel Injection Costs for Mechanically Injected Engines 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Cost to Engine Manufacturer 

Component Costs 

 Electronic Control Unit $3,500 $3,500 $3,500 $5,000 $5,000 $5,000 

 Common Rail Accumulators (each) $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 

 Number of Accumulators 3 6 8 9 12 18 

 Low Pressure Pump $2,000 $3,000 $4,000 $2,500 $3,500 $4,500 

 High Pressure Pump $3,500 $4,500 $6,000 $4,500 $6,000 $8,000 

 Modified injectors (each) $2,500 $2,500 $2,500 $3,500 $3,500 $3,500 

 Number of injectors 9 12 16 18 24 36 

Wiring Harness $2,500 $2,500 $2,500 $3,000 $3,000 $3,000 

Total Component Cost $40,000 $55,500 $72,000 $96,000 $125,500 $182,500 

Assembly 

 Labor (hours) 120 160 200 200 250 300 

 Cost ($23.85/hr) $2,862 $3,815 $4,769 $4,769 $5,962 $7,154 

Overhead @ 40% $1,145 $1,526 $1,908 $1,908 $2,385 $2,862 

Total Assembly Cost $4,006 $5,342 $6,677 $6,677 $8,346 $10,015 

Total Variable Cost $44,006 $60,842 $78,677 $102,677 $133,846 $192,515 

Markup @ 29% $12,762 $17,644 $22,816 $29,776 $38,815 $55,829 

Total Hardware RPE $56,768 $78,486 $101,493 $132,453 $172,662 $248,345 

Fixed Costs 

R&D Costs (1 year R&D) $688,000 $688,000 $688,000 $688,000 $688,000 $688,000 

Retooling Costs $1,000,000 $1,000,000 $1,000,000 $1,000,000 $1,000,000 $1,000,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $11,365 $11,365 $11,365 $11,365 $11,365 $11,365 

Total Costs $68,133 $89,850 $112,858 $143,818 $184,026 $259,710 

Cost per kW $15.1 $9.5 $6.3 $16.9 $12.3 $5.4 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

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Table 3-7. Common Rail Fuel Injection Costs for Electronic Engines 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Manufacturer 

Component Costs 

 Electronic Control Unit $500 $500 $500 $500 $500 $500 

 Common Rail Accumulators (each) $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 

 Number of Accumulators 3 6 8 9 12 18 

 Low Pressure Pump $1,000 $1,000 $1,000 $1,500 $1,500 $1,500 

 High Pressure Pump $1,500 $1,500 $1,500 $2,000 $2,000 $2,000 

 Modified injectors (each) $500 $500 $500 $750 $750 $750 

 Number of injectors 9 12 16 18 24 36 

Wiring Harness $500 $500 $500 $650 $650 $650 

Total Component Cost $14,000 $21,500 $27,500 $36,150 $46,650 $67,650 

Assembly 

 Labor (hours) 40 60 80 40 60 80 

 Cost ($23.85/hr) $954 $1,431 $1,908 $954 $1,431 $1,908 

Overhead @ 40% $382 $572 $763 $382 $572 $763 

Total Assembly Cost $1,335 $2,003 $2,671 $1,335 $2,003 $2,671 

Total Variable Cost $15,335 $23,503 $30,171 $37,485 $48,653 $70,321 

Markup @ 29% 

Total Hardware RPE 

$4,447 

$19,783 

$6,816 

$30,319 

$8,750 

$38,920 

$10,871 

$48,356 

$14,109 

$62,762 

$20,393 

$90,714 

Fixed Costs 

R&D Costs (0.5 year R&D) $344,000 $344,000 $344,000 $344,000 $344,000 $344,000 

Retooling Costs $500,000 $500,000 $500,000 $500,000 $500,000 $500,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $5,698 $5,698 $5,698 $5,698 $5,698 $5,698 

Total Costs $26,700 $34,868 $41,535 $48,850 $60,018 $81,685 

Cost per kW $5.9 $3.7 $2.3 $5.7 $4.0 $1.7 

3.4. Tier III Technology Costs 

As discussed in Section 2, several options have been discussed to meet proposed Tier III 

emission levels. These include engine modifications, fumigation, fuel emulsions, direct water 

injection, exhaust gas recirculation, selective catalytic reduction and seawater scrubbing. Fuel 

switching costs are discussed in Section 3.4. 

3.4.1. Engine Modifications 

Engine modifications to meet proposed Tier III emission levels include use of two stage 

turbochargers and electronic valve actuation. Table 3-8 shows incremental costs for engine 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

modifications to meet the proposed Tier III emission levels. Retooling costs represent 

turbocharger redesign and valve actuation modifications. 

Table 3-8. Differential Engine Modifications Costs to Meet Tier III Emission Levels 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Manufacturer 

Component Costs 

2 Stage Turbochargers 

(Incremental) $16,250 $20,900 $46,750 $28,000 $42,000 $61,000 

Electronic Intake Valves (each) $285 $285 $285 

Intake Valves per Cylinder 2 2 2 

Electronic Exhaust Valves (each) $285 $285 $285 $425 $425 $425 

Exhaust Valves per Cylinder 2 2 2 4 4 4 

Controller $3,750 $3,750 $3,750 $3,750 $3,750 $3,750 

Wiring $2,800 $2,800 $2,800 $2,800 $2,800 $2,800 

Total Component Cost $33,060 $41,130 $71,540 $44,750 $62,150 $87,950 

Markup @ 29% $9,587 $11,928 $20,747 $12,978 $18,024 $25,506 

Total Hardware RPE $42,647 $53,058 $92,287 $57,728 $80,174 $113,456 

Fixed Costs 

R&D Costs (1 year R&D) $688,000 $688,000 $688,000 $688,000 $688,000 $688,000 

Retooling Costs $700,000 $1,000,000 $1,300,000 $1,000,000 $1,300,000 $1,650,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $9,407 $11,365 $13,322 $11,365 $13,322 $15,605 

Total Costs $52,055 $64,422 $105,608 $69,092 $93,495 $129,061 

Cost per kW $11.6 $6.8 $5.9 $8.1 $6.2 $2.7 

3.4.2. Fumigation 

Fumigation costs include costs for the water storage tank, the humidifier, the heat exchanger 

and various pumps and piping and are shown in Table 3-9. Water tank cost details are shown 

in Table 3-10 and estimate storage of water for 250 hours of normal operation when operating in 

the emission control area (ECA). It is envisioned that the water tank is constructed of cold rolled 

steel 1 mm thick. Cold rolled steel prices are estimated at $686 per metric tonne and represent 

average steel prices in 2006.46 Water usage costs are shown in Table 3-11 and are estimated 

assuming a cost of $0.25/gallon for distilled water. For systems that use seawater, these costs 

should not be considered. Retooling costs are for redesign of the air intake system. 

46 MEPS Steel Prices On-line at http://www.steelonthenet.com/prices.html. 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-9. Fumigation Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Manufacturer 

Component Costs 

 Water Tank $2,036 $3,253 $4,885 $2,775 $3,939 $8,071 

 Humidifier $70,000 $120,000 $240,000 $190,000 $310,000 $700,000 

 Heat Exchanger $37,500 $47,000 $56,000 $47,000 $56,000 $75,000 

 Pump/Piping $5,600 $7,500 $9,500 $7,500 $9,500 $11,300 

Total Component Cost $109,536 $170,253 $300,885 $239,775 $369,939 $783,071 

Assembly 

 Labor (hours) 400 600 800 750 1000 1250 

 Cost ($23.85/hr) $9,538 $14,308 $19,077 $17,885 $23,846 $29,808 

Overhead @ 40% $3,815 $5,723 $7,631 $7,154 $9,538 $11,923 

Total Assembly Cost $13,354 $20,031 $26,708 $25,038 $33,385 $41,731 

Total Variable Cost $122,890 $190,284 $327,592 $264,813 $403,323 $824,802 

Markup @ 29% $35,638 $55,182 $95,002 $76,796 $116,964 $239,192 

Total Hardware RPE $158,528 $245,466 $422,594 $341,609 $520,287 $1,063,994 

Fixed Costs 

R&D Costs (1 year R&D) $688,000 $688,000 $688,000 $688,000 $688,000 $688,000 

Retooling Costs $1,000,000 $1,000,000 $1,000,000 $1,000,000 $1,000,000 $1,000,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $11,365 $11,365 $11,365 $11,365 $11,365 $11,365 

Total Costs $169,892 $256,831 $433,959 $352,974 $531,652 $1,075,359 

Cost per kW $37.8 $27.0 $24.1 $41.5 $35.4 $22.4 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-10. Fumigation Water Tank Costs 

Speed Medium Medium Medium Low Low Low
 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Water Tank Costs

 Fuel Amount (kg) 240,996 508,769 963,984 422,699 745,940 2,387,008 

 Density (kg/m^3) 1,000 1,000 1,000 1,000 1,000 1,000 

Tank Size (m^3) 289 611 1,157 423 746 2,387 

Tank Material (m^3) 0.26 0.43 0.66 0.34 0.49 1.07 

Tank Material Cost ($) $1,411 $2,321 $3,553 $1,817 $2,653 $5,756 

Assembly 

 Labor (hours) 5 6 7 10 12 15 

 Cost ($23.85/hr) $119 $143 $167 $238 $286 $358 

Overhead @ 40% $48 $57 $67 $95 $114 $143 

Total Assembly Cost $167 $200 $234 $334 $401 $501 

Total Variable Cost $1,578 $2,522 $3,787 $2,151 $3,053 $6,257 

Markup @ 29% $458 $731 $1,098 $624 $885 $1,814 

Total Hardware RPE $2,036 $3,253 $4,885 $2,775 $3,939 $8,071 

Table 3-11. Fumigation Distilled Water Costs 

Speed Medium Medium Medium Low Low Low
 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Distilled Water Costs 

 BSFC (g/kWh) 210 210 210 195 195 195 

Load factor 73% 73% 73% 73% 73% 73% 

 Water/Fuel Ratio 1.40 1.40 1.40 1.40 1.40 1.40 

 Water Use (kg/hr) 964 2,035 3,856 1,691 2,984 9,548 

 Water Cost per kg $0.0264 $0.0264 $0.0264 $0.0264 $0.0264 $0.0264 

 Water cost per hour $25 $54 $102 $45 $79 $252 

3.4.3. Fuel Emulsification 

Fuel emulsification costs include costs for the water storage tank, the ultrasonic homogenizer, 

the heat exchanger, and various pumps and piping. These are shown in Table 3-12. Water 

tank cost details are shown in Table 3-13 and estimate storage of water for 250 hours of normal 

operation when operating in the emission control area (ECA). It is envisioned that the water 

tank is constructed of cold rolled steel 1 mm thick. Water usage costs are shown in Table 3-14 

and are estimated assuming a cost of $0.25/gallon for distilled water. Retooling costs are for 

redesign of the fuel system to accommodate fuel emulsification. 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-12. Fuel Emulsification Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Manufacturer 

Component Costs 

 Water Tank $1,132 $1,767 $2,610 $1,611 $2,240 $4,386 

 Ultrasonic Homogenizer $37,500 $56,000 $75,000 $56,000 $75,000 $112,200 

 Heat Exchanger $9,400 $11,700 $14,000 $11,700 $14,000 $16,400 

 Pump/Piping $4,700 $5,600 $6,600 $5,600 $6,600 $7,500 

Total Component Cost $52,732 $75,067 $98,210 $74,911 $97,840 $140,486 

Assembly 

 Labor (hours) 240 320 400 320 400 480 

 Cost ($23.85/hr) $5,723 $7,631 $9,538 $7,631 $9,538 $11,446 

Overhead @ 40% $2,289 $3,052 $3,815 $3,052 $3,815 $4,578 

Total Assembly Cost $8,012 $10,683 $13,354 $10,683 $13,354 $16,025 

Total Variable Cost $60,745 $85,750 $111,564 $85,595 $111,194 $156,511 

Markup @ 29% $17,616 $24,867 $32,354 $24,822 $32,246 $45,388 

Total Hardware RPE $78,361 $110,617 $143,918 $110,417 $143,441 $201,899 

Fixed Costs 

R&D Costs (1 year R&D) $688,000 $688,000 $688,000 $688,000 $688,000 $688,000 

Retooling Costs $500,000 $500,000 $500,000 $500,000 $500,000 $500,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $8,103 $8,103 $8,103 $8,103 $8,103 $8,103 

Total Costs $86,463 $118,720 $152,020 $118,520 $151,543 $210,001 

Cost per kW $19.2 $12.5 $8.4 $13.9 $10.1 $4.4 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-13. Emulsification Water Tank Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Water Tank Costs

 Fuel Amount (kg) 86,070 181,703 344,280 150,964 266,407 852,503 

 Density (kg/m^3) 1,000 1,000 1,000 1,000 1,000 1,000 

Tank Size (m^3) 103 218 413 151 266 853 

Tank Material (m^3) 0.13 0.22 0.33 0.17 0.25 0.54 

Tank Material Cost ($) $711 $1,169 $1,790 $915 $1,336 $2,899 

Assembly 

 Labor (hours) 5 6 7 10 12 15 

 Cost ($23.85/hr) $119 $143 $167 $238 $286 $358 

Overhead @ 40% $48 $57 $67 $95 $114 $143 

Total Assembly Cost $167 $200 $234 $334 $401 $501 

Total Variable Cost $878 $1,370 $2,023 $1,249 $1,737 $3,400 

Markup @ 29% $255 $397 $587 $362 $504 $986 

Total Hardware RPE $1,132 $1,767 $2,610 $1,611 $2,240 $4,386 

Table 3-14. Emulsification Distilled Water Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Distilled Water Costs 

 BSFC (g/kWh) 210 210 210 195 195 195 

Load factor 73% 73% 73% 73% 73% 73% 

 Water/Fuel Ratio 0.50 0.50 0.50 0.50 0.50 0.50 

 Water Use (kg/hr) 344 727 1,377 604 1,066 3,410 

 Water Cost per kg $0.0264 $0.0264 $0.0264 $0.0264 $0.0264 $0.0264 

 Water cost per hour $9 $19 $36 $16 $28 $90 

3.4.4. Direct Water Injection 

Direct water injection costs include costs for the water storage tank, a low pressure module, a 

high pressure module, flow fuses, water injectors, related piping, and the control unit and wiring 

and are shown in Table 3-15. Water tank cost details are shown in Table 3-16 and estimate 

storage of water for 250 hours of normal operation when operating in the ECA. It is envisioned 

that the water tank is constructed of cold rolled steel 1 mm thick. Water usage costs are shown 

in Table 3-17 and are estimated assuming a cost of $0.25/gallon for distilled water. Retooling 

costs are for redesign of the cylinder head to accommodate the direct water injectors. 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-15. Direct Water Injection Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Manufacturer 

Component Costs 

 Water Tank $1,132 $1,767 $2,610 $1,611 $2,240 $4,386 

 Low Pressure Module $4,700 $7,000 $9,500 $9,500 $19,000 $3,800 

 High Pressure Module $9,500 $14,000 $19,000 $19,000 $38,000 $75,000 

 Flow Fuses (each) $1,900 $1,900 $1,900 $1,900 $1,900 $1,900 

 Water Injectors (each) $2,400 $2,400 $2,400 $2,400 $2,400 $2,400 

 Number per cylinder 1 2 3 3 6 12 

Piping $5,600 $7,500 $9,500 $9,500 $14,000 $19,000 

 Control Unit/Wiring $9,500 $11,300 $13,000 $11,300 $13,000 $15,000 

Total Component Cost $69,132 $144,767 $260,010 $128,311 $292,640 $736,386 

Assembly 

 Labor (hours) 500 750 1000 1000 1500 2000 

 Cost ($23.85/hr) $11,923 $17,885 $23,846 $23,846 $35,769 $47,692 

Overhead @ 40% $4,769 $7,154 $9,538 $9,538 $14,308 $19,077 

Total Assembly Cost $16,692 $25,038 $33,385 $33,385 $50,077 $66,769 

Total Variable Cost $85,825 $169,805 $293,395 $161,696 $342,717 $803,155 

Markup @ 29% $24,889 $49,244 $85,084 $46,892 $99,388 $232,915 

Total Hardware RPE $110,714 $219,049 $378,479 $208,588 $442,105 $1,036,070 

Fixed Costs 

R&D Costs (2 years R&D) $1,376,000 $1,376,000 $1,376,000 $1,376,000 $1,376,000 $1,376,000 

Retooling Costs $10,000,000 $10,000,000 $10,000,000 $10,000,000 $10,000,000 $10,000,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $74,891 $74,891 $74,891 $74,891 $74,891 $74,891 

Total Costs $185,605 $293,940 $453,371 $283,479 $516,997 $1,110,962 

Cost per kW $41.2 $30.9 $25.2 $33.4 $34.5 $23.1 

ICF International 3-12 U.S. Environmental Protection Agency 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-16. DWI Water Tank Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Water Tank Costs

 Fuel Amount (kg) 86,070 181,703 344,280 150,964 266,407 852,503 

 Density (kg/m^3) 1,000 1,000 1,000 1,000 1,000 1,000 

Tank Size (m^3) 103 218 413 151 266 853 

Tank Material (m^3) 0.13 0.22 0.33 0.17 0.25 0.54 

Tank Material Cost ($) $711 $1,169 $1,790 $915 $1,336 $2,899 

Assembly 

 Labor (hours) 5 6 7 10 12 15 

 Cost ($23.85/hr) $119 $143 $167 $238 $286 $358 

Overhead @ 40% $48 $57 $67 $95 $114 $143 

Total Assembly Cost $167 $200 $234 $334 $401 $501 

Total Variable Cost $878 $1,370 $2,023 $1,249 $1,737 $3,400 

Markup @ 29% $255 $397 $587 $362 $504 $986 

Total Hardware RPE $1,132 $1,767 $2,610 $1,611 $2,240 $4,386 

Table 3-17. DWI Distilled Water Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Distilled Water Costs 

 BSFC (g/kWh) 210 210 210 195 195 195 

Load factor 73% 73% 73% 73% 73% 73% 

 Water/Fuel Ratio 0.50 0.50 0.50 0.50 0.50 0.50 

 Water Use (kg/hr) 344 727 1,377 604 1,066 3,410 

 Water Cost per kg $0.0264 $0.0264 $0.0264 $0.0264 $0.0264 $0.0264 

 Water cost per hour $9 $19 $36 $16 $28 $90 

3.4.5. Exhaust Gas Recirculation 

Exhaust gas recirculation costs include a supply pump, a sludge tank, piping, a waste pump, a 

recirculation pump, a scrubber unit, a separator, an EGR valve, and the control unit and wiring. 

Costs for an EGR system are given in Table 3-18. Retooling costs are for exhaust system 

redesign. Table 3-19 provide details on the sludge tank. Sludge is estimated to build up at 0.05 

g/kWh with a sludge density of 1,300 kg/m3

 based upon an average 20 percent EGR rate. The 

sludge tank is envisioned to be constructed of cold rolled steel 1 mm thick. The tank will hold 

sludge generated from 500 hours of engine operation. 

ICF International 3-13 U.S. Environmental Protection Agency 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-18. Exhaust Gas Recirculation Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Manufacturer 

Component Costs 

 Supply Pump $1,900 $2,600 $3,600 $2,600 $4,400 $7,000 

 Sludge Tank $268 $345 $435 $511 $635 $859 

Piping $2,800 $3,800 $4,700 $3,700 $4,700 $5,600 

 Waste Pump $1,900 $2,800 $3,800 $2,800 $4,700 $7,500 

 Recirculation Pump $1,900 $2,800 $3,800 $2,800 $4,700 $7,500 

 Scrubber Unit $23,500 $35,000 $56,000 $32,700 $56,000 $112,200 

Separator $1,900 $2,800 $3,800 $2,800 $3,800 $4,700 

EGR Valve $7,000 $9,500 $11,700 $9,500 $11,700 $14,000 

 Control Unit/Wiring $4,700 $4,700 $4,700 $4,700 $4,700 $4,700 

Total Component Cost $45,868 $64,345 $92,535 $62,111 $95,335 $164,059 

Assembly 

 Labor (hours) 200 300 400 300 400 500 

 Cost ($23.85/hr) $4,769 $7,154 $9,538 $7,154 $9,538 $11,923 

Overhead @ 40% $1,908 $2,862 $3,815 $2,862 $3,815 $4,769 

Total Assembly Cost $6,677 $10,015 $13,354 $10,015 $13,354 $16,692 

Total Variable Cost $52,545 $74,361 $105,888 $72,127 $108,689 $180,751 

Markup @ 29% $15,238 $21,565 $30,708 $20,917 $31,520 $52,418 

Total Hardware RPE $67,783 $95,925 $136,596 $93,044 $140,208 $233,169 

Fixed Costs 

R&D Costs (1 year R&D) $688,000 $688,000 $688,000 $688,000 $688,000 $688,000 

Retooling Costs $2,000,000 $2,000,000 $2,000,000 $2,000,000 $2,000,000 $2,000,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $17,889 $17,889 $17,889 $17,889 $17,889 $17,889 

Total Costs $85,672 $113,814 $154,485 $110,932 $158,097 $251,058 

Cost per kW $19.0 $12.0 $8.6 $13.1 $10.5 $5.2 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-19. Sludge Tank Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Sludge Tank Costs 

Sludge Rate, g/kWh 0.05 0.05 0.05 0.05 0.05 0.05 

Sludge Amount (kg) 112.50 237.50 450.00 212.50 375.00 1,200.00 

Sludge Tank size (m^3) 0.104 0.219 0.415 0.196 0.346 1.108 

Tank Material (m^3) 0.01 0.01 0.02 0.01 0.01 0.03 

Tank Material Cost ($) $41 $67 $103 $63 $91 $198 

Assembly 

 Labor (hours) 5 6 7 10 12 14 

 Cost ($23.85/hr) $119 $143 $167 $238 $286 $334 

Overhead @ 40% $48 $57 $67 $95 $114 $134 

Total Assembly Cost $167 $200 $234 $334 $401 $467 

Total Variable Cost $208 $268 $337 $396 $492 $666 

Markup @ 29% $60 $78 $98 $115 $143 $193 

Total Hardware RPE $268 $345 $435 $511 $635 $859 

3.4.6. Selective Catalytic Reduction 

Selective catalytic reduction (SCR) costs include the urea tank, the reactor, dosage pump, urea 

injectors, piping, bypass valve, the acoustic horn, a cleaning probe and the control unit and 

wiring. Detailed costs are shown in Table 3-20. Retooling costs are for redesign of the exhaust 

system to accommodate the SCR unit. Detailed costs for the urea tank are shown in Table 3-21 

and estimate storage of urea for 250 hours of normal operation when operating in the emission 

control area (ECA). Because of the corrosive nature of urea, it is envisioned that the urea tank 

is constructed of 304 stainless steel 1 mm thick at a cost of $2,747.20 per metric tonne.47 Urea 

usage costs are shown in Table 3-22 and are estimated assuming a cost of $1.52/gallon for 

urea with a density of 1.09 grams per cubic centimeter. 

47 http://www.metalprices.com/FreeSite/metals/stainless_product/product.asp#Tables for 2006. 

ICF International 3-15 U.S. Environmental Protection Agency 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-20. Selective Catalytic Reduction Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Supplier 

Component Costs 

 Aqueous Urea Tank $1,194 $1,868 $2,765 $1,690 $2,356 $4,636 

Reactor $200,000 $295,000 $400,000 $345,000 $560,000 $1,400,000 

 Dosage Pump $9,500 $11,300 $13,000 $11,300 $13,000 $15,000 

 Urea Injectors (each) $2,400 $2,400 $2,400 $2,400 $2,400 $2,400 

 Number of Urea Injectors 3 6 8 12 16 24 

Piping $4,700 $5,600 $6,600 $5,600 $7,500 $9,500 

Bypass Valve $4,700 $5,600 $6,600 $5,600 $6,600 $7,500 

Acoustic Horn $9,500 $11,300 $13,000 $11,700 $14,000 $16,400 

 Cleaning Probe $575 $575 $575 $700 $700 $700 

Control Unit/Wiring $14,000 $14,000 $14,000 $19,000 $19,000 $19,000 

Total Component Cost $251,369 $359,643 $475,740 $429,390 $661,556 $1,530,336 

Assembly 

 Labor (hours) 1000 1200 1500 1200 1600 2000 

 Cost ($23.85/hr) $23,846 $28,615 $35,769 $28,615 $38,154 $47,692 

Overhead @ 40% $9,538 $11,446 $14,308 $11,446 $15,262 $19,077 

Total Assembly Cost $33,385 $40,062 $50,077 $40,062 $53,415 $66,769 

Total Variable Cost $284,753 $399,704 $525,816 $469,452 $714,971 $1,597,106 

Markup @ 29% $82,578 $115,914 $152,487 $136,141 $207,342 $463,161 

Total Hardware RPE $367,332 $515,618 $678,303 $605,593 $922,313 $2,060,266 

Fixed Costs 

R&D Costs (2 years R&D) $1,376,000 $1,376,000 $1,376,000 $1,376,000 $1,376,000 $1,376,000 

Retooling Costs $2,000,000 $2,000,000 $2,000,000 $2,000,000 $2,000,000 $2,000,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $22,699 $22,699 $22,699 $22,699 $22,699 $22,699 

Total Costs $390,031 $538,317 $701,002 $628,292 $945,012 $2,082,965 

Cost per kW $86.7 $56.7 $38.9 $73.9 $63.0 $43.4 

ICF International 3-16 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

 

 

 

 

 

 

 

 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-21. Urea Tank Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Urea Tank Costs

 Urea Amount (kg) 12,910 27,255 51,642 22,645 39,961 127,875 

 Density (kg/m^3) 1,090 1,090 1,090 1,090 1,090 1,090 

Tank Size (m^3) 14 30 57 21 37 117 

Tank Material (m^3) 0.04 0.06 0.09 0.05 0.07 0.14 

Tank Material Cost ($) $758 $1,248 $1,909 $977 $1,426 $3,093 

Assembly 

 Labor (hours) 5 6 7 10 12 15 

 Cost ($23.85/hr) $119 $143 $167 $238 $286 $358 

Overhead @ 40% $48 $57 $67 $95 $114 $143 

Total Assembly Cost $167 $200 $234 $334 $401 $501 

Total Variable Cost $925 $1,448 $2,143 $1,310 $1,826 $3,594 

Markup @ 29% $268 $420 $621 $380 $530 $1,042 

Total Hardware RPE $1,194 $1,868 $2,765 $1,690 $2,356 $4,636 

Table 3-22. Urea Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Aqueous Urea Costs

 BSFC (g/kWh) 210 210 210 195 195 195 

Load factor 73% 73% 73% 73% 73% 73% 

 Aqueous Urea Rate 7.5% 7.5% 7.5% 7.5% 7.5% 7.5% 

 Aqueous Urea (kg/hr) 52 109 207 91 160 512 

 Aqueous Urea Cost per kg $0.3684 $0.3684 $0.3684 $0.3684 $0.3684 $0.3684 

 Aqueous Urea Cost per hour $19 $40 $76 $33 $59 $188 

3.4.7. Sea Water Scrubbers 

Sea water scrubber costs include the supply pump, the sludge tank, piping, a waste pump, a 

recirculation pump, the scrubber unit, an oil/water separator, an SO2 monitor, and the control 

unit and wiring. Retooling costs are for redesign of the exhaust system to accommodate the 

scrubber unit. Detailed costs are given in Table 3-23. Detailed costs for the sludge tank are 

given in Table 3-24 and assume a sludge buildup rate of 0.25 g/kWh48 and a sludge density of 

1,300 kg/m3

. The sludge tank is envisioned to be constructed of cold rolled steel 1 mm thick. 

The tank will hold sludge generated for 500 hours of engine operation. 

48 Entec UK Ltd, “Service Contract on Ship Emissions: Assignment, Abatement and Market Based Instruments – Task 

2c – SO2 Abatement,” August 2005 available at http://ec.europa.eu/environment/air/pdf/task2_so2.pdf. 

ICF International 3-17 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

 

 

 

 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-23. Sea Water Scrubber Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Costs to the Supplier 

Component Costs 

 Supply Pump $9,500 $14,000 $19,000 $14,000 $23,500 $37,500 

 Sludge Tank $350 $481 $641 $637 $818 $1,256 

Piping $4,700 $5,600 $6,600 $5,600 $7,500 $9,500 

 Waste Pump $9,500 $11,300 $13,000 $11,300 $13,000 $15,000 

 Recirculating Pump $9,500 $11,300 $13,000 $11,300 $13,000 $15,000 

 Scrubber Unit $215,000 $355,000 $550,000 $340,000 $500,000 $1,125,000 

Separator $7,000 $8,000 $9,000 $8,000 $9,000 $10,000 

SO2 Monitor $9,500 $9,500 $9,500 $9,500 $9,500 $9,500 

 Control Unit/Wiring $28,000 $28,000 $28,000 $28,000 $28,000 $28,000 

Total Component Cost $293,050 $443,181 $648,741 $428,337 $604,318 $1,250,756 

Assembly 

 Labor (hours) 600 800 1000 1000 1500 2000 

 Cost ($23.85/hr) $14,308 $19,077 $23,846 $23,846 $35,769 $47,692 

Overhead @ 40% $5,723 $7,631 $9,538 $9,538 $14,308 $19,077 

Total Assembly Cost $20,031 $26,708 $33,385 $33,385 $50,077 $66,769 

Total Variable Cost $313,081 $469,888 $682,126 $461,722 $654,395 $1,317,525 

Markup @ 29% $90,794 $136,268 $197,817 $133,899 $189,774 $382,082 

Total Hardware RPE $403,875 $606,156 $879,943 $595,621 $844,169 $1,699,608 

Fixed Costs 

R&D Costs (1 year R&D) $688,000 $688,000 $688,000 $688,000 $688,000 $688,000 

Retooling Costs $2,000,000 $2,000,000 $2,000,000 $2,000,000 $2,000,000 $2,000,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $17,889 $17,889 $17,889 $17,889 $17,889 $17,889 

Total Costs $421,763 $624,045 $897,831 $613,510 $862,058 $1,717,497 

Cost per kW $93.7 $65.7 $49.9 $72.2 $57.5 $35.8 

ICF International 3-18 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

 

 

 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-24. Sludge Tank Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Sludge Tank Costs

 Sludge Rate, g/kWh 0.25 0.25 0.25 0.25 0.25 0.25 

 Sludge Amount (kg) 562.50 1,187.50 2,250.00 1,062.50 1,875.00 6,000.00

 Sludge Tank size (m^3) 0.519 1.096 2.077 0.981 1.731 5.538 

Tank Material (m^3) 0.02 0.03 0.05 0.03 0.04 0.09 

Tank Material Cost ($) $105 $172 $264 $160 $233 $506 

Assembly 

 Labor (hours) 5 6 7 10 12 14 

 Cost ($23.85/hr) $119 $143 $167 $238 $286 $334 

Overhead @ 40% $48 $57 $67 $95 $114 $134 

Total Assembly Cost $167 $200 $234 $334 $401 $467 

Total Variable Cost $272 $372 $497 $494 $634 $974 

Markup @ 29% $79 $108 $144 $143 $184 $282 

Total Hardware RPE $350 $481 $641 $637 $818 $1,256 

3.5. Fuel Switching Hardware Costs 

In this section, hardware costs related to fuel switching are discussed. Fuel cost differentials 

have been discussed in another EPA report.33 Three cases are discussed in Section 2.3, 

namely: 

	 Case 0: Vessels meet all requirements of a ECA and require no modifications or 

retrofits (baseline). 

	 Case 1: A newly built vessel requires additional equipment to meet ECA 

requirements over comparable new vessels. 

	 Case 2: Existing vessels will require retrofits to meet ECA requirements. 

Case 0 assumes that the vessels have sufficient storage tank capacity currently for fuel 

switching and all the proper equipment necessary to accomplish fuel switching in a ECA area. 

Based upon their survey, ARB estimates that 78 percent of all ships fall into this category. 

However, ARB believes that this is an underestimation and that the vast majority of ships fall 

into this category.41 There is no hardware costs associated with Case 0. 

Case 1 assumes that new vessels will be built with additional distillate fuel storage capacity and 

systems over existing ships. Costs include additional distillate fuel storage tanks, an LFO fuel 

separator, an HFO/LFO blending unit, a 3-way valve, an LFO cooler, filters, a viscosity meter, 

and various pumps and piping. These costs are shown in Table 3-25. Details on additional 

tank costs are shown in Table 3-26. Distillate tanks are assumed to be constructed of cold 

rolled steel 1 mm thick and double walled and will hold an additional 250 hours of propulsion 

and auxiliary engine operation while within a ECA. 

ICF International 3-19 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

 

 

 

 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-25. Case 1 Fuel Switching Costs (New Construction) 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Cost to Supplier 

Component Costs 

 Additional Tanks $3,409 $5,511 $8,341 $4,562 $6,548 $13,733 

 LFO Separator $2,800 $3,300 $3,800 $3,800 $4,200 $4,700 

 HFO/LFO Blending Unit $4,200 $4,700 $5,600 $4,700 $5,600 $6,600 

 3-Way Valve $950 $1,400 $1,900 $1,400 $1,900 $2,800 

 LFO Cooler $2,400 $2,800 $3,300 $2,800 $3,800 $4,700 

Filters $950 $950 $950 $950 $950 $950 

Viscosity Meter $1,400 $1,400 $1,400 $1,400 $1,400 $1,400 

 Piping/Pumps $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 

Total Component Cost $18,109 $22,061 $27,291 $21,612 $26,398 $36,883 

Assembly 

 Labor (hours) 240 320 480 320 480 600 

 Cost ($23.85/hr) $5,723 $7,631 $11,446 $7,631 $11,446 $14,308 

Overhead @ 40% $2,289 $3,052 $4,578 $3,052 $4,578 $5,723 

Total Assembly Cost $8,012 $10,683 $16,025 $10,683 $16,025 $20,031 

Total Variable Cost $26,121 $32,744 $43,316 $32,295 $42,423 $56,914 

Markup @ 29% $7,575 $9,496 $12,562 $9,366 $12,303 $16,505 

Total Hardware RPE $33,696 $42,240 $55,877 $41,661 $54,725 $73,419 

Fixed Costs 

R&D Costs (0.25 year R&D) $172,000 $172,000 $172,000 $172,000 $172,000 $172,000 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $1,233 $1,233 $1,233 $1,233 $1,233 $1,233 

Total Costs $34,929 $43,473 $57,110 $42,894 $55,958 $74,652 

Cost per kW $7.8 $4.6 $3.2 $5.0 $3.7 $1.6 

ICF International 3-20 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

 

 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-26. Additional Fuel Tank Storage Costs 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Propulsion 

 BSFC (g/kWh) 210 210 210 195 195 195 

Load factor 73% 73% 73% 73% 73% 73% 

Auxiliary 

 Power (kW) 1,022 2,158 4,090 1,931 3,408 10,906 

 BSFC (g/kWh) 227 227 227 227 227 227 

Load factor 31% 31% 31% 31% 31% 31% 

Combined

 Fuel Amount (kg) 190,001 401,114 760,006 335,666 592,352 1,895,528 

 Density (kg/m^3) 960 960 960 960 960 960 

Tank Size (m^3) 238 501 950 350 617 1,975 

Tank Material (m^3) 0.46 0.75 1.15 0.59 0.87 1.88 

Tank Material Cost ($) $2,476 $4,072 $6,232 $3,203 $4,675 $10,145 

Assembly 

 Labor (hours) 5 6 7 10 12 15 

 Cost ($23.85/hr) $119 $143 $167 $238 $286 $358 

 Overhead@40% $48 $57 $67 $95 $114 $143 

Total Assembly Cost $167 $200 $234 $334 $401 $501 

Total Variable Cost $2,642 $4,272 $6,466 $3,537 $5,076 $10,646 

Markup @ 29% $766 $1,239 $1,875 $1,026 $1,472 $3,087 

Total Hardware RPE $3,409 $5,511 $8,341 $4,562 $6,548 $13,733 

Case 2 is for retrofitting ships with equipment to allow fuel switching. It is similar to Case 1 

costs, however, additional labor is allocated to installing the systems on a ship and additional 

R&D is provided to test systems on existing ships. Case 2 costs are given in Table 3-27. 

ICF International 3-21 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

 

 

 

 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-27. Case 2 Fuel Switching Costs (Retrofits) 

Speed Medium Medium Medium Low Low Low 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Hardware Cost to Supplier 

Component Costs 

 Additional Tanks $3,409 $5,511 $8,341 $4,562 $6,548 $13,733 

 LFO Separator $2,800 $3,300 $3,800 $3,800 $4,200 $4,700 

 HFO/LFO Blending Unit $4,200 $4,700 $5,600 $4,700 $5,600 $6,600 

 3-Way Valve $950 $1,400 $1,900 $1,400 $1,900 $2,800 

 LFO Cooler $2,400 $2,800 $3,300 $2,800 $3,800 $4,700 

Filters $950 $950 $950 $950 $950 $950 

Viscosity Meter $1,400 $1,400 $1,400 $1,400 $1,400 $1,400 

 Piping/Pumps $2,000 $2,000 $2,000 $2,000 $2,000 $2,000 

Total Component Cost $18,109 $22,061 $27,291 $21,612 $26,398 $36,883 

Assembly 

 Labor (hours) 480 640 960 640 960 1200 

 Cost ($23.85/hr) $11,446 $15,262 $22,892 $15,262 $22,892 $28,615 

Overhead @ 40% $4,578 $6,105 $9,157 $6,105 $9,157 $11,446 

Total Assembly Cost $16,025 $21,366 $32,049 $21,366 $32,049 $40,062 

Total Variable Cost $34,133 $43,427 $59,340 $42,979 $58,447 $76,945 

Markup @ 29% $9,899 $12,594 $17,209 $12,464 $16,950 $22,314 

Total Hardware RPE $44,032 $56,021 $76,549 $55,442 $75,397 $99,259 

Fixed Costs 

R&D Costs (0.33 year R&D) $227,040 $227,040 $227,040 $227,040 $227,040 $227,040 

Marine Society Approval $5,000 $5,000 $5,000 $5,000 $5,000 $5,000 

Engines/yr. 40 40 40 40 40 40 

Years to recover 5 5 5 5 5 5 

Fixed cost/engine $1,618 $1,618 $1,618 $1,618 $1,618 $1,618 

Total Costs $45,265 $57,254 $77,782 $56,675 $76,630 $100,492 

Cost per kW $10.1 $6.0 $4.3 $6.7 $5.1 $2.1 

3.6. Differential Fuel Consumption 

Fuel consumption increases/decreases were calculated for a 1 percent change in BSFC. The 

values shown in Table 3-28 can be scaled up or down relative to the amount of fuel 

consumption benefit or penalty. 

ICF International 3-22 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

 

 

 

Costs of Emission Reduction Technologies for Category 3 Marine Engines 

Economic Impact 

Table 3-28. Hourly fuel use change estimated for a one percent change in brake specific fuel 

consumption 

Speed Medium Medium Medium Low Low Low
 

Engine Power (kW) 4,500 9,500 18,000 8,500 15,000 48,000 

Cylinders 9 12 16 6 8 12 

Liters/cylinder 35 65 95 380 650 1400 

Engine Speed (rpm) 650 550 500 130 110 100 

Load Factors, % of hp 73% 73% 73% 73% 73% 73% 

Avg BSFC, g/kWh 210 210 210 195 195 195 

HFO Fuel Usage Tonnes per hour 0.69 1.45 2.75 1.21 2.13 6.82 

3.7. IMO Testing Costs 

IMO testing is done on a representative engine for an engine family. This engine represents the 

worst case specification (i.e., the highest NOx emissions). It is emission tested on a test bed 

before sending it to the customer. Other similar engines are referred to as an engine family and 

are not tested. 

A technical file is submitted with the engine. It would contain the identification of the 

components, settings and operating values of the engine that influence NOx emissions. The 

critical components are marked with IMO-ID numbers and relevant parameters are identified, 

providing an easy means of compliance checking onboard the ship. Identification of the full 

range of allowable adjustments or alternatives for the components of the engine are also listed 

along with a system of onboard NOx verification procedures (component and setting checks) to 

verify compliance with the IMO NOx emission limits during onboard verification surveys. 

The cost of Marine Society approval is estimated at $5,000. 

ICF International 3-23 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099 
 

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Costs of Emission Reduction Technologies for Category 3 Marine Engines 

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ICF International 3-24 U.S. Environmental Protection Agency 

EPA Contract EP-C-06-094, WA 2-08 April 20099