European Commission

Directorate General

Environment

Service Contract on

Ship Emissions:

Assignment,

Abatement and

Market-based

Instruments

Task 2c – SO2 Abatement

Final Report

August 2005

Entec UK Limited

Certificate No. FS 13881

Report for

European Commission

Directorate-General-Environment

Directorate C - Unit C1

Main Contributors

Alistair Ritchie (Entec)

Emily de Jonge (Entec)

Christoph Hugi (Entec)

David Cooper (IVL)

Issued by

..................................................................

Christoph Hugi

Approved by

..................................................................

Alistair Ritchie

Entec UK Limited

Windsor House

Gadbrook Business Centre

Gadbrook Road

Northwich

Cheshire

CW9 7TN

England

Tel: +44 (0) 1606 354800

Fax: +44 (0) 1606 354810

13554

h:\projects\em-260\13000 projects\13554 pp ship

emissions\reports\task 2 final report\task 2 so2 final_final report

16_09_05v2.doc

European

Commission

Directorate General

Environment

Service Contract on

Ship Emissions:

Assignment,

Abatement and

Market-based

Instruments

Task 2c – SO2 Abatement

Final Report

August 2005

Entec UK Limited

Certificate No. EMS 69090

In accordance with an environmentally responsible approach,

this document is printed on recycled paper produced from 100%

post-consumer waste, or on ECF (elemental chlorine free) paper

Final Report

i

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Executive Summary

Introduction

This report forms part of the deliverables under Task 2 of the European Commission contract on

Ship Emissions: Assignment, Abatement and Market-Based Instruments.

Task 2 requires an investigation of the costs, emission reduction potential and practicalities of

ship emissions abatement technologies. The technologies to be considered are:

• Task 2a: The use of shore-side electricity (see separate report on shore-side

electricity);

• Task 2b: NOx abatement techniques (see separate report on NOX techniques);

• Task 2c: SO2 abatement techniques with focus on sea water scrubbing (this report).

This is the report for Task 2c on SO2 abatement techniques.

This report investigates the costs, emissions reductions and cost effectiveness of specific SO2

reduction measures on ships. The following three measures are investigated:

1. Sea water scrubbing;

2. Fuel switching from 2.7% sulphur residual oil (RO) down to 1.5% sulphur RO; and

3. Fuel switching from 2.7% sulphur residual oil (RO) down to 0.5% sulphur RO.

The main focus of this report, as required by the project specification, is Sea Water Scrubbing.

As such, it has been possible to give only limited consideration to fuel switching within the

resources of this study.

Details of Sea Water Scrubbing

Background

One of the most versatile, readily available and cost-effective scrubbing processes is sea water

scrubbing, due to sea water’s natural alkalinity. Furthermore, sea water already contains large

quantities of sulphur and can be considered as a relatively safe sulphur reservoir.

The basic principle of operation for a Sea Water Scrubber relies on hot exhaust gases mixing in

a turbulent cascade with seawater whereupon SO2 in the exhaust is transferred to the seawater.

The seawater is re-circulated, and the solid particles removed from the exhaust gas are trapped

in a settling or sludge tank where they are collected for disposal.

Early trials of Sea Water Scrubbers

To our knowledge, the first prototype exhaust gas seawater system for ship emission control

was installed in 1991. This demonstrated that a reduction of SO2 emissions up to 92% was

possible. At the normal load conditions measured however, the prototype demonstrated a

sulphur removal rate in the range of 71% to 73%.

An additional early demonstration of a sea water scrubber (in conjunction with a Selective

Catalytic Reduction unit and particle eductor) was installed in June 1993. The results showed
Final Report

ii

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

an SO2 removal efficiency of 90%, but the study concluded that the potential for an even higher

reduction exists by optimisation of the sea water/exhaust gas capacity ratio.

Development of the EcoSilencer®

Marine Energy Ltd. (MEL) undertook a comprehensive field trial in May 1998. The study also

outlined the possibility of recovering the waste heat from the exhaust in the sea water and

thereby achieving fuel savings by reducing the need to operate conventional auxiliary boilers.

A 96% SO2 removal rate was observed.

A new prototype scrubber, the EcoSilencer®, was fitted for testing onboard a ferry in August

2001. Independent stack sampling consultants initially showed a 94% SO2 reduction but around

3 months later this was reduced to 85%.

A more recent round of commercial trials with the EcoSilencer® onboard P&O Line’s

passenger ferry Pride of Kent took place during autumn 2004. The scope, performance and

costs of this project will outline the most up-to date assessment of the technique and is

discussed in this report.

Impact on emissions

Operating with a 2.5% sulphur fuel, SO2 reduction rates of 68-94% have been achieved. The

scrubbing efficiency is linked to the flow rate of sea water contacting with the exhaust. The

worst results experienced, with restricted sea water flow rates, were around 65%. By over

supplying the system with water removal rates of 94% were achieved. By operating the system

within the existing design parameters removal rates of 75% to 80% can be achieved. A

reduction efficiency rate of 75% is assumed in this study. It is also worth noting that MES

expect that with improved scrubber design, the EcoSilencer® will be able to sustain around

90% reduction in SO2 emissions.

Discharge water quality

The quality of the discharge water must comply with the appropriate environmental legislation.

The IMO OILPOL has a limit on the concentration of petroleum hydrocarbons which can be

discharged overboard, of 15ppm. The EcoSilencer® trial demonstrated that the discharge water

from the scrubber contained significantly lower levels of petroleum hydrocarbons than this

limit.

The IMO has not specified limits for other components and characteristics of discharge water,

such as pH, suspended solids and heavy metals.

Emissions reductions

Table 1 presents the estimated mid range values of emission reduction efficiencies of the SO2

abatement techniques considered in this study.
Final Report

iii

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Table 1 Emission reduction efficiencies

Measure % Emissions reduction (-) / increase (+) per vessel

SO2 NOX PM VOC

Sea water scrubbing -75% 0% -25%

1

±

Fuel switching 2.7->1.5% S fuel -44% ± -18% ±

Fuel switching 2.7->0.5% S fuel -81% ± -20%

2

±

Section 3.3 presents details of the impact of these measures on other emissions and noise.

Costs

Table 2 presents the estimated mid range values of cost-effectiveness of the SO2 abatement

techniques, expressed in terms of €/tonne SO2 abated. The associated uncertainty is considered

in Section 1.2.

Table 2 Costs per tonne of emissions reduced for SO2 abatement measures based on midrange values (Note 1) (€/tonne SO2)

Measure Ship type Small Vessel Medium Vessel Large Vessel

(€/tonne SO2) (€/tonne SO2) (€/tonne SO2)

Sea water scrubbing New 390 351 320

Sea water scrubbing Retrofit 576 535 504

Fuel switching: 2.7% S

fuel to 1.5% S fuel

New/retrofit 2,053 (1,230) 2,050 (1,230) 2,045 (1,230)

Fuel switching: 2.7% S

fuel to 0.5% S fuel

New/retrofit 1,439 (1,690) 1,438 (1,690) 1,434 (1,690)

Note

1. For fuel switching, there is a wide range of estimated values for the price premia of low sulphur fuels.

The main results relate to the use of BeicipFranlab (2003) average fuel price differential information, whilst

the figures in brackets represent the use of Concawe estimates.

1 MES measured sludge production from the Pride of Kent as 0.2 g/kWh and particles suspended in

overboard water as 0.05g/kWh. Based on a PM emission factor of 0.8 g/kWh in the exhaust for the type

of auxiliary engine used in MES’s trials, the PM removal rate by the EcoSilencer® can be approximated

as around 31%. However since this calculation assumed that all the sludge consists of particulates, and

that the suspended solids in the scrubber inflow is negligible, the actual removal rate is likely to be lower

than 31%. A conservative estimate of 25% PM reductions was therefore chosen.

2 Conservative figure. It is estimated that PM removal will be more than 18% but is likely to be

significantly less than 63% (US EPA 2003).
Final Report

iv

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

More details of estimated costs, including estimated capital and operating costs for different size

vessels, specific costs (€/kW capital, €/MWh operating) and total costs scaled up for all EUflagged vessels are given in Sections 4, 5 and 6.

A comparison of the cost effectiveness of SO2 abatement measures for ships against SO2

abatement for other sources is given in Section 5.2.
Final Report

v

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Contents

1. Introduction 1

1.1 General 1

1.2 Uncertainty of Results 1

2. Technical Description 3

2.1 Background 3

2.2 Experience with Sea Water Scrubbing on Marine Vessels 5

2.2.1 Early trials of Sea Water Scrubbers in Marine Applications 5

2.2.2 Development of the EcoSilencer® 6

2.2.3 Pride of Kent EcoSilencer® Trials 7

2.2.4 Discharge Water Quality 8

2.2.5 Sulphuric Acid Mist after Scrubber Treatment on Ships 8

3. Emissions Reductions 11

3.1 Emissions Reduced by Sea Water Scrubbing (SWS) 11

3.2 Emissions Reduced by Fuel Switching 12

3.3 Other Emissions (CO, CO2, CH4, N2O and noise) 14

4. Costs 15

4.1 Sea Water Scrubbing 15

4.1.1 Capital Costs 15

4.1.2 Economies of Scale 15

4.1.3 Lifespan 16

4.1.4 Operating and Maintenance Costs 16

4.1.5 Total Costs per vessel 17

4.2 Fuel Switching 18

4.2.1 Capital Costs and Lifespan 18

4.2.2 Operating Costs 18

4.2.3 Total Costs for Fuel Switching 19

5. Cost Effectiveness 21

5.1 Cost effectiveness of SO2 abatement techniques for ships 21
Final Report

vi

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

5.2 Comparison of cost effectiveness of SO2 abatement

measures for ships compared with SO2 abatement for other

sources 22

6. Scale up for all EU-Flagged Ships 27

Table 1 Emission reduction efficiencies iii

Table 2 Costs per tonne of emissions reduced for SO2 abatement measures based on mid-range

values (Note 1) (€/tonne SO2) iii

Table 3.1 Assumed reduction efficiencies of the sea water scrubbing technology (SWS) 12

Table 3.2 SO2 emissions reduction, EcoSilencer®, (reduction efficiency 75%) 12

Table 3.3 Assumed reduction efficiencies of Fuel Switching 13

Table 3.4 Saved emissions by Fuel Switching 14

Table 4.1 Estimation of specific EcoSilencer capital costs 15

Table 4.2 Operating and maintenance costs 16

Table 4.3 Accepted oily waste under direct fee, Port of Rotterdam 17

Table 4.4 Costs for sea water scrubbing 17

Table 4.5 Fuel cost premium for low sulphur RO 19

Table 4.6 Total costs, Fuel switching, 2.7 -> 1.5% Sulphur RO (figures in brackets show results

using Concawe price premium) 19

Table 4.7 Total costs, Fuel switching, 2.7 -> 0.5% Sulphur RO (figures in brackets show results

using Concawe price premium) 20

Table 5.1 Cost Effectiveness of SO2 Reduction Measures in €/tonne abated (note 1) (figures in

brackets show results using Concawe price premium) 21

Table 5.2 Cost Effectiveness of SO2 Reduction Measures in €/tonne fuel used (note 1) (figures in

brackets show results using Concawe price premium) 21

Table 5.3 Indicative average marginal abatement costs for sectors with ‘beyond BAU’ SO2

measures supplied by IIASA for 2010 and 2020 25

Table 6.1 Number of ships in the EU-flagged and world fleet 27

Table 6.2 Costs for applying measures to existing vessels in the EU-flagged fleet (estimates based

on CONCAWE fuel prices in brackets) 27

Figure 2.1 Schematic of EcoSilencer’s® scrubbing recirculation system 4

Figure 2.2 The EcoSilencer® incorporated into the exhaust train and installed on the Pride of Kent 7

Figure 5.1 Cost curve for SO2 for 2010 showing position in cost curve where additional measures for

ships would fit (all measures for ships are for medium size vessels) (Source: IIASA, 2004) 23

Figure 5.2 Cost curve for SO2 for 2020 showing position in cost curve where additional measures for

ships would fit (all measures for ships are for medium size vessels) (Source: IIASA, 2004) 24

Appendix 1 Pride of Kent Trials Air and Water Emission Monitoring Reports
Final Report

1

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

1. Introduction

1.1 General

This report forms part of the deliverables under Task 2 of the European Commission contract on

Ship Emissions: Assignment, Abatement and Market-Based Instruments.

Task 2 requires an investigation of the costs, emission reduction potential and practicalities of

ship emissions abatement technologies. The technologies to be considered are:

• Task 2a: The use of shore-side electricity (see separate report on shore-side

electricity);

• Task 2b: NOx abatement techniques (see separate report on NOX techniques);

• Task 2c: SO2 abatement techniques with focus on sea water scrubbing (this report).

This is the report for Task 2c on SO2 abatement techniques.

This report investigates the costs, emissions reductions and cost effectiveness of specific SO2

reduction measures on ships. The following three measures are investigated:

1. Sea water scrubbing

2. Fuel switching from 2.7% sulphur residual oil (RO) down to 1.5% sulphur RO

3. Fuel switching from 2.7% sulphur residual oil (RO) down to 0.5% sulphur RO

The main focus of this report, as required by the project specification, is Sea Water Scrubbing.

As such, it has been possible to give only limited consideration to fuel switching within the

resources of this study.

The main input data used to assess the sea water scrubbing process applied to ships are based on

the trials of the EcoSilencer® on the Pride of Kent vessel.

The full methodology and underlying assumptions are outlined in the General report.

Chapter 2 contains the technical description of the sea water scrubbing process and existing case

studies. Chapter 3 assesses the expected emission reduction achieved by the three measures and

Chapter 4 covers the associated cost to achieve these reductions. Chapter 5 summarises the

estimated cost effectiveness of the individual measures and Chapter 6 estimates the cost if these

measures are implemented on EU-flagged ships.

1.2 Uncertainty of Results

The two key results of this study are the costs of a measure and the achieved emission reduction

by this measure i.e.
Final Report

2

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Emission reduction (tonne of pollutant/year)

Cost of measure i (€/year)

Cost − Effectivenessmeasure i(€/tonne of pollutant) =

Costs of measures: It is estimated that the costs derived in this study are subject to a 30%

uncertainty range compared to the best estimate cost figure which are quoted. The key

contributors to the uncertainty in the above estimates include:

• Sea water scrubbing on ships has not been commercially exploited and the market

prices have not been developed. The quoted costs are estimates based on the

experience with the prototypes and discussions with experts;

• Costs for low sulphur fuel mainly depend on supply, demand, sulphur content of

explored crude oil and technology. The market for low sulphur fuels for ships

(1.5% and 0.5% sulphur levels have been investigated) have not been properly

developed and volatility of oil markets is generally high; and

• Inherent variations in costs of retrofitting abatement equipment at different ships

due to ship specific factors.

Emission reductions: It is estimated that the emission reduction derived in this study are

subject to a 20% uncertainty range compared to the best estimate emission reduction figures

which are quoted. This is caused by a number of factors including:

• The variation in possible designs of Sea Water Scrubber;

• The level of maintenance of the equipment;

• The operating modes and load factors of the ship; and

• The variation in sulphur contents of fuels.

Based on these uncertainty ranges it can be estimated that the cost-effectiveness of measures

derived in this study are subject to an approximate 35% uncertainty range compared to the best

estimate cost effectiveness figures which are quoted.
Final Report

3

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

2. Technical Description

2.1 Background

The use of liquid scrubbers to remove gaseous sulphur dioxide is, at least on land-based

combustion units, a well-established practise (from 1930s onwards). More commonly termed as

Flue Gas Desulphurisation (FGD), several design options exist including impingement trays,

venturi, fan scrubbers and spray towers. These techniques have been demonstrated with many

applications such as in the production of pulp and paper, steel, mining and in power generation.

One of the most versatile, readily available and cost-effective scrubbing processes is sea water

scrubbing, due to sea water’s natural alkalinity. Furthermore, sea water already contains large

quantities of sulphur (around 0.1% on weight) and can be considered as a safe sulphur reservoir.

Most land-based scrubber designs are not directly transferable to ships at face value due to size,

cost and complexity considerations, and consequently manufacturers of land-based scrubbers

have seemed initially reluctant to develop scrubbers for use on board ships. Nonetheless,

several sea trials have been undertaken to develop sea water scrubbing for marine applications.

Interestingly, the first use of exhaust gas seawater scrubbers in the marine industry was not

directed to the problem concerning SO2 emission control. Instead, the scrubbers were seen as a

cheap means to produce inert gas for reducing the fire hazard in the cargo tanks of tankers while

unloading. By the 1970s, their use was widespread. Even in these cases, reductions of

particulates (PM) and SO2 (by as much as 97%) from the exhaust were noted (Zhou and

Montgomery, 1999).

The introduction of scrubbers for SO2 emission reductions onboard ships has however been

relatively limited in comparison to other technologies such as NOx abatement technologies.

This has largely been due to the ability to reduce SO2 emissions by using low-sulphur fuels.

However, due to predicted low-sulphur fuel supply limitations, relatively high operating costs

and other practical difficulties (Skjolsvik, 2003), the scrubber option is receiving increasing

attention as a cost-effective alternative (Gregory and Trivett, 2002).

This study has mainly drawn from the results and findings of the trial of the Eco-Silencer® sea

water scrubbing on the Pride of Kent. The basic principle of operation for the Eco-Silencer®

relies on hot exhaust gases mixing in a turbulent cascade with seawater whereupon SO2 in the

exhaust is transferred to the seawater. The design aims at achieving a 95% SO2 reduction

depending on water temperature and salinity. To ensure that the surface area for contact

between gas and water is high, and sufficient time for absorption of pollutants is provided, a

patented, compact mixing process was developed.

Figure 2.1 shows a schematic scrubbing system. The seawater is re-circulated

3

, and the solid

particles removed from the exhaust gas are trapped in a settling or sludge tank where they are

3 The rate of pH change in the re-circulating water is a simple indicator of SO2 removal and may therefore

have an implication for monitoring applications.
Final Report

4

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

collected for disposal. Disposal involves either burning the sludge in the ship’s incinerator or

disposing of it ashore. Filtered and used seawater can then pass onto the ship’s existing

bilgewater treatment system.

4

Further details of the system can be found in the literature e.g.

Gregory and Trivett, 2002; Holness, 2003; DME International, 2004.

Figure 2.1 Schematic of EcoSilencer’s® scrubbing recirculation system

4 Bilgewater systems are installed onboard ships to treat bilge water. Bilge water is produced from ship

activities such as clearing of cargo tanks and engine rooms. Bilge water contains oil and other

contaminants, and treatment of this water produces an oily sludge.
Final Report

5

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

2.2 Experience with Sea Water Scrubbing on Marine

Vessels

2.2.1 Early trials of Sea Water Scrubbers in Marine Applications

To our knowledge, the first prototype exhaust gas seawater system for ship emission control

was installed in 1991 on Color Line’s passenger ferry M/S Kronprins Harald serving the Oslo -

Kiel route. The tests lasted ca. 1,700 operating hours and demonstrated that a reduction of SO2

emissions up to 92% was possible (European Commission, 1999). At the normal load

conditions measured however, the prototype demonstrated a sulphur removal rate in the range of

71% to 73% for salinities down to 14% (Ives and Klokk, 1993). The discharged wastewater

was characterised by a low pH and various toxic organic pollutants and metals mainly

associated with the particles. Compared to the initial project targets for pollutant reductions, a

vast deviation was demonstrated for particle removal. Also, contradictory to the technology

originators expectations, no removal of NOx was observed.

An additional early demonstration of a sea water scrubber (in conjunction with a Selective

Catalytic Reduction unit and particle eductor) formed part of a Kvaerner/Norske Shell project

(Marine Engineers Review, 1995). The plant was installed in June 1993 on the Norske Shell

tanker MT Fjordshell that operates with a 10,800 kW main engine, three auxiliary engines, and

two boilers generating around 90,000 Nm

3

/hr of exhaust gas. The results showed a SOx removal

efficiency of 90%, but the study concluded that a potential for an even higher reduction exists

with an optimisation of the sea water/exhaust gas capacity ratio.

The environmental impact of the particulate-containing wastewater (which included soot,

copper, vanadium and nickel) was assessed (Skjolsvik, 2004). It was concluded that efficient

mixing in the wake of the ship (dilution by a factor of 2,000:1 within 50 m from the vessel’s

stern) meant that the exposure time to marine organisms would be small and the toxic effect

negligible. Although in harbour operations the dilution would be smaller, the environmental

effect of the process water was still presumed to be insignificant.

The overall conclusion from the project team was that the effectiveness of the plant had been

proven according to the scrubber design expectations (85-95% SO2 removal). In addition, the

automation of the system had meant little extra work for the crew onboard. As a general

conclusion it was reported that the degree of economic justification for the system would

depend on the ship’s fuel consumption, the price differential between high and low sulphur fuel,

the cost of the plant and eventual penalties incurred in lost cargo space. In the MT Fjordshell

case, the scrubber system was deemed less expensive than the use of low sulphur fuel.

Parallel to trials at sea, some experience with exhaust scrubbers for marine diesel engines have

been conducted at laboratory engine test facilities. In one example (Zhou and Montgomery,

1999), high SO2 reductions (> 95%), CO reductions (around 30%) with signs of NOx and PM

reductions and without significant changes in fuel consumption were observed for a 36 kW

Perkins high–speed engine.

5 CO2 emissions are not effected in any significant way. The

cooling effect of the exhaust gases was illustrated in this study (380

oC down to 50oC) with

raised scrubbing water temperatures (11

oC up to 50oC). This result pointed the way for future

material considerations for scrubbers since titanium is free from all corrosion below 80

oC.

5 The impact on CO2 emissions were not reported.
Final Report

6

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

In a second more recent example, the University of Dundee are involved with a patented

scrubber design aimed at removing particulates and SO2 (Cairns and Graham, 2004). The

underlying concept relies on the particulates being filtered from the scrubber liquid, which in

turn is heated to re-evolve the SO2. Water vapour is then condensed out, to leave dry SO2 gas,

which is converted to SO3 over a vanadium oxide catalyst, and dissolved in water to form

sulphuric acid. In this way the pollutant can be converted to a useful by-product.

2.2.2 Development of the EcoSilencer®

Marine Energy Ltd. (MEL) undertook a comprehensive field trial in May 1998 onboard the

Canadian ice breaker Louis S. St.-Laurent (Trivett et al., 1999). The trials were conducted

during 22 days of a 6-week transatlantic voyage. In this system the “i400” pilot plant scrubber

treated a partial stream of the exhaust from one of the three auxiliary engines onboard

(1,200 kW). In particular, the i400 was built to work at low exhaust back-pressures typical of

marine exhaust systems.

The study also outlined the possibility of recovering the waste heat from the exhaust in the sea

water and thereby achieving fuel savings by reducing the need to operate conventional auxiliary

boilers. Regarding SO2 reduction, a 96% removal rate was observed with a 70-80% reduction

in particulates (for sizes larger than 1 micron) and a 4% reduction in NO. An improved NO

reduction was proposed for future scrubber designs using higher concentrations of sea water.

Furthermore, three inspections revealed that fouling of the plant was minimal.

MEL’s development work continued in co-operation with MAN B&W. A new prototype

scrubber, the Eco-Silencer®, was fitted for testing onboard the Canadian RoPax ferry Leif

Ericson, which used to be known as the Stena Challenger (Gregory and Trivett, 2002, Clarke,

2004) in August 2001. The Eco-Silencer unit was supplied by Marine Exhaust Solutions

(MES

6

) a division of DME International in Canada and used on a 1,500 kW auxiliary engine

running on heavy fuel oil with a sulphur content of ca. 3.5% by weight. The installation, where

the scrubber replaced the exhaust silencer in the funnel casing was carried out during a normal

scheduled dock period alongside the terminal (that is no additional time out of operational

service was required). In contrast to the i400 prototype, the Eco-Silencer scrubber was a fullscale plant and treated the entire exhaust stream from the engine.

7

One of the specific aims of the Leif Ericson trials was to investigate wastewater quality though a

water treatment plant and if necessary apply alternate water treatment components. In addition

the owners of the vessel, Canada’s Marine Atlantic, were particularly concerned about soot

emissions. Crew officers noted a visible improvement in smoke opacity during the tests and

measurements confirmed the following reductions: PM2 reduced by 98%; PM1.5 reduced by

74%; PM1 reduced by 59%; and PM0.05 reduced by 45% (Clarke, 2004).

Regarding SO2 removal, independent stack sampling consultants initially showed a 94%

reduction but around 3 months later this was reduced to 85%. Unfortunately most of the test

period was hampered with industrial action, and subsequently led to a winter stoppage that led

to ice damage within the scrubber. Thus in the spring of 2002 the system was removed (Clarke,

2004).

6 Marine Energy Ltd became Marine Exhaust Solutions on joining DME International in 2000.

7 Besides SO2, NOx and PM removal, the Eco-Silencer also reduces exhaust odour and noise.
Final Report

7

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

The developmental work thus far undertaken, in particular on Louis S. St.-Laurent and Leif

Ericson, has subsequently led to the next round of commercial trials with the Eco-Silencer

onboard P&O Line’s passenger ferry Pride of Kent during autumn 2004. The scope,

performance and costs of this project will outline the most up-to date assessment of the

technique and is discussed below.

2.2.3 Pride of Kent EcoSilencer® Trials

The results from the EcoSilencer trials on the Pride of Kent are investigated in this study. The

results incorporated in this study are the latest results from the trial, covering emission

reductions, cost and discharge water quality. Appendix 1 includes the reports by MES on this

trial.

The trial comprised of four EcoSilencers® on four 1.2 MW auxiliary engines. The trial lasted

over 16 months during which the auxiliary engines were operational for approximately 11,680

hours (100% of the time) (MES 2005).

Figure 2.2 The EcoSilencer® incorporated into the exhaust train and installed on the Pride of

Kent
Final Report

8

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

2.2.4 Discharge Water Quality

The quality of the discharge water must comply with the appropriate environmental legislation.

The IMO OILPOL has a limit on the concentration of petroleum hydrocarbons which can be

discharged overboard, of 15ppm. The EcoSilencer® trial demonstrated that the discharge water

from the scrubber contained significantly lower levels of petroleum hydrocarbons than this limit

(AQS/UKAS, 2004; Westech/AQS, 2004, 1 and 2; MES 2004; MES 2005, and shown in

Appendix 1).

The IMO has not specified limits for other components and characteristics of discharge water,

such as pH, suspended solids and heavy metals. The US EPA has outlined limits for these

components and characteristics, under the Quality Criteria for Water 1986, EPA 440/5-86-001.

The EcoSilencer® trial demonstrated that the discharge water met some of the EPA criteria, but

exceeded others (AQS/UKAS, 2004; Westech/AQS, 2004, 1 and 2; MES 2004; MES 2005, and

shown in Appendix 1). Whether these exceedences can be avoided by alteration in scrubber

design would need further investigation.

2.2.5 Sulphuric Acid Mist after Scrubber Treatment on Ships

Potential problems associated with Sea Water Scrubbing are thought to include the possibility of

scrubber emissions falling out as acidic precipitation in the vicinity of the chimney and then

causing local acidification problems including potential corrosion of materials and exposure to

individuals. This was a problem of early land based flue gas desulphurisation (FGD) plants but

the problem is now well understood and there exist technical solutions to mitigate this problem

8

.

When fuels containing sulphur are burned, mainly sulphur dioxide (SO2) is produced, but also a

small fraction of sulphur trioxide (SO3). The chemical process under consideration for the

formation of sulphuric acid is:

2SO2 + O2 --> 2SO3

SO3 + H2O --> H2SO4

At temperatures >340°C present during combustion processes, sulphuric acid (H2SO4) is not

present, only sulphur trioxide (SO3). When gases are cooled, however, sulphur trioxide will

react very readily with any available water to form sulphuric acid. If sulphuric acid forms in a

gas sample, as long as it remains in the vapour phase it generally causes little or no problem.

However when the concentrations of water and sulphuric acid are sufficiently high to form acid

mists at ambient temperature, corrosion problems are likely to occur.

When sulphur dioxide is present in gas samples at concentrations of a few hundred ppm or less

as it will be after the scrubber treatment (approx. 300ppm), formation of acid mist is normally

not reported to be a problem unless the ambient temperature is quite low. However because

after a scrubber treatment the exhaust gas stream will have a high water content and will be

8 Land based flue gas desulphurisation (FGD) plants have typically reduction rates of 92% for SO2

. They usually use

a reheat system to reduce plume visibility (caused by moisture in the exhausted gas stream) and to increase the

discharge plume buoyancy, thereby preventing it from grounding too close to the power station. Such a reheat

system also has the effect of reducing the propensity for acid mist formation. The cleaned flue gas is reheated using

either an indirect steam heater or heat extracted from the dirty gas on the inlet side of the scrubber (which is usually

at about 110-140°C), using a regenerative gas heater.
Final Report

9

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

cooled down in the scrubber and after leaving the chimney by entrained ambient air there might

be conditions that allow forming sulphuric acid mist

9

.

SO3 acid dew points are around 125 to 170°C depending upon the water vapour (not liquid

droplet) content and SO3 content of the flue gas. Scrubbed gas will be very close to the ambient

scrubbing water temp (5-20°C). Prior to exiting the scrubber, flue gases usually pass through an

impingement type droplet separator (deflector baffles within the gas stream) to reduce the

entrained water droplet concentration of the discharged gas to around 50 mg/Nm

3

. The flue

gases are then usually reheated (by say 20-30°C) to eliminate visible steam plume.

Consequently the flue will generally be below the SO3 acid dew point. To accommodate this,

appropriate acid-resistant construction materials are usually employed downstream of the

scrubber system.

Provided the exit velocity of the flue gas is sufficiently high and reheat has been applied,

sufficient plume buoyancy can be achieved to minimise the potential for local plume grounding

and possible acid deposition. This can be verified during design using atmospheric dispersion

modelling techniques.

The formation of acid mist will start in a similar way to the process of forming clouds with very

small droplets. Typical initial cloud drops have a diameter of about 0.002mm but need only

about 0.01m/s lift to stay aloft or would fall with a terminal velocity of only 0.01m/s without

uplift.

For a ship travelling at sea there is very little probability that the mist will impact on the ship

under normal conditions i.e. the upward lift in the exhaust plume is more than big enough to

keep the mist aloft for long enough for the ship to travel out of the fallout zone. Any mist

falling into the sea will be neutralised in the same fashion as is happening in the scrubber and is

of little environmental concern.

For a ship at berth under most normal conditions except still wind conditions there is only a

small probability that the mist will impact directly on the ship. However at berth there are other

surfaces at risk when the wind blows from the sea and where this mist lands on metal surfaces,

it can create a point of corrosion. Additionally, on non metallic surfaces it may cause a reddish

brown stain. It is reported that it might even “corrode” non-metallic materials such as fibreglass

and plastics.

According to MARPOL Annex VI port states are permitted to set environmental criteria for the

use of scrubbers in enclosed ports and coastal areas, and sulphuric mist may be one of the

criteria they will wish to consider.

In general, based on these comments sulphuric acid mist formation is currently not thought to be

a significant problem for scrubber treatment on ships, though it is a potential issue to be further

looked into for specific conditions and cases, e.g. at berth.

However it does not diminish the environmental benefits of scrubbers to reduce SO2 emissions

into the air. On the contrary, SO2 reductions may be enhanced as the described process could

lead to a further reduction of SO2 in the exhaust gas and the ambient air.

9

By lowering the temperature of the gas sample sufficiently (typically down to 60°-75°C) while it still contains

significant amounts of water, sulphuric acid can be forced to condense.
Final Report

10

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554
Final Report

11

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

3. Emissions Reductions

3.1 Emissions Reduced by Sea Water Scrubbing (SWS)

As mentioned earlier, the Pride of Kent EcoSilencer trials represent the most up-to-date

assessment of Sea Water Scrubbing at the time of writing.

Trial results are based on tests undertaken by the monitoring company Westech’s subsidiary Air

Quality Solutions (AQS). The results of AQS’s trials were supplied by MES (AQS/UKAS,

2004; Westech/AQS, 2004, 1 and 2; MES 2004; MES 2005).

Operating with a 2.5% sulphur fuel, SO2 reduction rates of 68-94% have been achieved

(Westech/AQS/MES 2004). The scrubbing efficiency is linked to the flow rate of sea water

contacting with the exhaust. The worst results experienced, with restricted sea water flow rates,

were around 65% (MES 2004, 1). However the test results attached in Appendix 1 demonstrate

that higher rates are achieved. By over supplying the system with water removal rates of 94%

were achieved. By operating the system within the existing design parameters removal rates of

75% to 80% have been sustained. It is also worth noting that MES (2004) expect that with

improved scrubber design, the EcoSilencer® will be able to sustain around 90% reduction in

SO2 emissions. A reduction efficiency rate of 75% is assumed in this study.

These tests were undertaken on 2.5% sulphur fuel, and are therefore likely to have shown a

slightly higher SO2 removal rate for engines using 2.7% sulphur fuel, the assumed baseline

average for RO in this study. However since there is no data available for scrubbing

efficiencies for engines using 2.7% sulphur, the scrubber efficiencies for 2.5% sulphur fuel are

assumed.

Measurements of NOx reductions recorded very low NOx removal rates. Therefore it is

assumed that NOx removal is likely to be insignificant (Westech/AQS 2004, 1). VOC emission

reductions were not measured.

Since the EcoSilencer® scrubs the exhaust, it is likely to be able to remove PM, however this

was not measured during the trial. A mass balance approach was used to estimate PM reduction

experienced on the Pride of Kent.

The Pride of Kent trial was undertaken on 1,200 kW auxiliary engines. For one engine running

at 65% load, MES measured sludge production from the Pride of Kent as 0.2 g/kWh (MES

2005). Particles suspended in overboard water were measured as 450 to 790 μg/L. Using the

average value of 620 μg/L, a water outflow of 60 t/h per unit, the amount of particles contained

in the overboard water are equivalent to 0.05 g/kWh. Total particles removed were therefore up

to 0.25 g/kWh.

Based on a PM emission factor of 0.8 g/kWh in the exhaust for the type of auxiliary engine used

in MES’s trials, the PM removal rate by the EcoSilencer® can be estimated at around 31%.

However, this calculation assumed that all the sludge consists of particulates, and that the

suspended solids in the scrubber inflow is negligible. Therefore particulate removal may be

less, and a conservative estimate of 25% is used in this study. Reduction rates confirmed by
Final Report

12

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

future measurements might therefore further improve the overall environmental benefits of this

system.

It should be noted that MES (2004, 1) expect that the EcoSilencer® is capable of PM reductions

of the order of 80%. MES is planning further EcoSilencer® trials to test PM reduction

efficiency (MES 2005).

11

Table 3.1 outlines the emission reduction efficiencies assumed for the assessment of the sea

water scrubbing technology, based on the EcoSilencer® trials.

Table 3.1 Assumed reduction efficiencies of the sea water scrubbing technology (SWS)

NOx SO2 VOC PM sfc

Reduction efficiencies SWS 0% 75% Unknown 25% 0% (note 1.)

Note 1: The scrubber causes only a small backpressure on the engine, from which MES have not

measured any impact on engine efficiency and fuel consumption (MES 2004).

Table 3.2 depicts the expected SO2 emission reduction per year for the different vessel sizes.

The underlying assumptions are summarised in the General Report.

Table 3.2 SO2 emissions reduction, EcoSilencer®, (reduction efficiency 75%)

Vessel

Current Small Medium Large

SO2 reduction (t/year) 129 423 1,058

3.2 Emissions Reduced by Fuel Switching

Creation of SO2 emissions from fuel combustion is directly related to the sulphur content of

fuels. Therefore the reduction efficiency of fuel switching is related to the reduction in sulphur

content of the fuels.

It is likely that fuel switching will be done by using low sulphur residual oil (RO) rather than

using marine distillate (MD). This is because the premium for low sulphur fuel is €200020-89 per

tonne for RO (BecipFranlab 2003) and around €110 and €130 per tonne for switching to 0.2%

and 0.1% sulphur MD

10

respectively. Therefore the following two scenarios were further

considered:

10

Prices from BeicipFranlab are converted to €2000. Prices assumed for RO and MD are €113 per tonne

and €227 per tonne respectively (Jiven 2004). Although fuel prices rose for the remainder of 2004, for
Final Report

13

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

1. switching from 2.7% sulphur to 1.5% sulphur and

2. switching from 2.7% sulphur to 0.5% sulphur.

A reduction in the sulphur content of fuels will reduce PM emissions, however this is difficult to

quantify with the extent of currently available data and many emission measurement

methodologies do not include PM reductions from a reduction in the sulphur content of fuel

(Cooper 2004). A US EPA study (US EPA 2003 3) estimates PM reductions for dropping from

2.7% to 1.5% sulphur fuel as 18%. PM reductions for dropping from 2.7% to 0.5% sulphur fuel

will therefore be most likely greater than 18%, but less than the 63% reduction seen from

switching to marine distillate (US EPA 2003 3). As a working assumption, a figure of 20% PM

reduction is used in this study. The actual reduction will depend on various factors including

the source of crude oil and the nature of the petroleum refining operations used to produce the

RO.

11

Reduction in VOC is not quantified. Since it is assumed that the fuel will still be RO, the

specific fuel consumption is not expected to change significantly. Table 3.3 outlines the

reduction efficiencies assumed in this study for fuel switching. Table 3.4 summarises the

expected SO2 emission reduction per year for the different vessel sizes.

Table 3.3 Assumed reduction efficiencies of Fuel Switching

Fuel S % NOx SO2 VOC PM sfc

Fuel Switching 1 2.7 -> 1.5 0% 44% unknown 18% 0%

Fuel Switching 2 2.7 -> 0.5 0% 81% unknown 20% 0%

example, the cost of 0.2% sulphur MD in June 2004 was €325 per tonne, such high prices are not

expected to last. Specific fuel consumption used is 200 g/kWh.

11

EU air quality limits for PM concentrations come into force in 2005 for PM10 (less than 10μm in

diameter), and include 24 hour limits and annual average limits. These limits do not distinguish between

the primary particles which are directly emitted, and the secondary particles which are formed when SO2

and NOx emissions oxidise in ambient air. In the context of the forthcoming Clean Air for Europe

strategy the Commission is considering setting new air quality limits for PM2.5.
Final Report

14

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Table 3.4 Saved emissions by Fuel Switching

Vessel

Fuel S % Reduction Small Medium Large

Fuel Switching 1 2.7 -> 1.5 SO2 (t/year) 76 251 627

Fuel Switching 2 2.7 -> 0.5 SO2 (t/year) 140 459 1,149

3.3 Other Emissions (CO, CO2, CH4, N2O and noise)

The effects of the EcoSilencer® on other emissions such as CO

12

, CO2

12

, CH4 and N2O have not

been measured. It can be assumed that since the specific fuel consumption of engines are

unlikely to be impacted by use of an EcoSilencer®, and that the use of an EcoSilencer® will not

impact upon combustion conditions, that there may be no significant impact on emissions of

these pollutants except where a scrubbing effect may potentially take place.

An EcoSilencer® is designed to replace engine silencers. The EcoSilencer is quoted to increase

noise attenuation since noise will encounter a silencer containing significant quantities of water

(MES 2004).

Fuel switching is not expected to have any significant effects on the emissions mentioned in this

heading.

12 Although reductions of CO of 30% have been measured on test facilities (see Section 2.2.1), we are not

aware of measurement of CO emissions from full scale practical application. CO2 emissions are not

effected in any significant way.
Final Report

15

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

4. Costs

4.1 Sea Water Scrubbing

4.1.1 Capital Costs

An estimation of capital costs for the scrubbers installed on the Pride of Kent is shown in Table

4.1. MES (2004) estimate that new build installations would cost 20-40% less than retrofitting,

therefore this study assumes an average cost reduction of 30% for new build installations.

Table 4.1 Estimation of specific EcoSilencer capital costs

Costs from the Pride of Kent Capital Costs (current)

Retrofit Capex (€/kW installed) 168

New build Capex (€/kW installed) 118

These capital costs include a waste water treatment system and demisters required to reduce

carryover of scrubbing water into the exhaust. If carryover was not reduced, the SO2 removal

efficiency of the scrubbers would be impacted. The EcoSilencer® system passes the scrubbing

water through several stages of cyclone separation to remove solids, oils and any associated

contaminants. The Pride of Kent trials (Westech/AQS 2004, 3 and 4) showed that this

equipment enabled oily wastes to be removed to 0.042 ppm, which is significantly below the

IMO’s OILPOL limit of 15 ppm.

MES (2004) estimate that with a significant quantity of EcoSilencer® units manufactured,

capital costs per unit could be considerably reduced. MES (2004) estimate future Capex costs

for retrofit could be as low as €120/kW. It is interesting to note that capital costs for stationary

sea water scrubbing systems cost around €100/kW (Lurgi 2004)

13

.

4.1.2 Economies of Scale

Cost estimations from MES (2004) were based on a 27 MW size engine. MES have not

provided costs for smaller engines, and therefore details are not available on possible economies

of scale.

13 Based on €3.5-5 million for a 40 MW system (Lurgi 2004). An important cost difference between

stationary and marine costs relates to water treatment. Stationary SWS systems use concrete lagoons to

aerate the scrubbing water before discharging back into the sea. These lagoons add significant costs,

whereas onboard ships it is likely that the existing bilgewater treatment system can be used at minimal

additional costs. The cost estimate quoted by Lurgi does not include costs for waste water treatment

lagoons.
Final Report

16

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

4.1.3 Lifespan

The EcoSilencer® will be subject to significant temperature differentials and to both reducing

and oxidising environments. One end of the silencer will be subjected to hot and dry conditions

where the exhaust enters, and cold and humid where the seawater and exhaust are mixed. DME

(2004) state that the material specification will have a minimum lifespan of 15 years. This

study will therefore assume that the equipment lifespan is 15 years.

4.1.4 Operating and Maintenance Costs

General Operating and Maintenance Costs

Experience of operating and maintenance costs on the Pride of Kent were that costs were

minimal (MES 2004, 1). These minimal costs relate to costs for pump operation, maintenance

and sludge disposal (see below). To reflect likely costs, cost estimates are made as shown in

Table 4.2. These costs are estimated as a fraction of new build capital costs.

Table 4.2 Operating and maintenance costs

Vessel size Small Medium Large

O&M costs per year (% of new build capex) 3% 2% 1%

Sludge Disposal

To meet water discharge specifications, the wastewater from the scrubber needs to be cleaned to

remove particles and oil. This water treatment process produces an oily sludge, which needs

disposal. Although oily sludges are produced from other ship activities, such as such the

clearing of cargo tanks or engine room bilges, operation of a sea water scrubber will increase

the volume of oily sludge generated.

Oily wastes which have been removed from scrubbing water are stored and disposed of in port.

Ports charge for the disposal of oily wastes, however the majority of ports have an fixed

(‘direct’) fee for sludge disposal which allows disposal of a certain amount of waste (Hayward

and Dzanic, 2003). If this limit is not exceeded, sludge from the scrubber will not add extra

costs. For example, the Port of Rotterdam charges an indirect fee for ships based on main

engine capacity, which covers the disposal of a certain amount of oily waste.

Results from the Pride of Kent EcoSilencer® trials demonstrated a small sludge production rate

of 0.2 kg/MWh (MES 2004,3). Such a small sludge production rate would produce small

sludge quantities per journey. It is likely that this amount of additional sludge production per

journey from operating a SWS system will not make a ship exceed the amount of sludge

disposal allowed under a direct fee. Table 4.3 shows an example for the port of Rotterdam and

a journey duration of 550 hours. Since any sludge disposal costs will be relatively small, it is

assumed this is covered by the estimated operating costs shown in Table 4.2. However it was

claimed that there might be an issue with the acidity of the sludge that might cause additional

disposal problems and costs. The characteristic of the seawater scrubbing sludge and its

disposal would therefore need to be further investigated to better understand any potential

additional cost implications.
Final Report

17

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Table 4.3 Accepted oily waste under direct fee, Port of Rotterdam

Main engine capacity Maximum amount of

oily waste under

indirect fee (m

3

)

Estimated oily sludge

production (m

3

) from SWS for

a journey of 550 hours

14

.

Small (< 6,000 kW) 3 <0.5

Medium (>= 6,000 - <15,000 kW) 3-10 0.5-<1.5

Large (>= 15,000 kW) 15-20 1.5-<10

4.1.5 Total Costs per vessel

Table 4.4 summarises the current costs for sea water scrubbing based on the EcoSilencer® data

collected from the Pride of Kent trials by MES (2004).

Table 4.4 Costs for sea water scrubbing

Vessel

Small Medium Large

New build capex (€) 418,656 1,350,048 3,386,880

Equipment lifespan (year) 15 15 15

Annualised costs (€/year) 37,700 121,460 304,630

Capex per kW installed (€/kW) 118 118 118

Retrofit capex (€) 598,080 1,928,640 4,838,400

Equipment lifespan (year) 12.5 12.5 12.5

Annualised costs (€/year) 61,750 199,090 499,440

Capex per kW installed (€/kW) 168 168 168

Operating and Maintenance (O&M) costs (€/year) 12,560 27,001 33,869

Opex per MWh (€/MWh) 0.8 0.5 0.3

Total annual costs - new build (€/year) 50,260 148,461 338,499

Total annual costs - retrofit (€/year) 74,310 226,091 533,309

14 Assumed density of sludge of 1,300 kg/m3
Final Report

18

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

4.2 Fuel Switching

4.2.1 Capital Costs and Lifespan

For fuel switching techniques, vessels have the option of either entirely switching to alternative

fuels (including the same fuel type but at a different sulphur content) or operating on dual-fuel

mode, with separate fuel storage tanks for each fuel (or split storage tanks). It should be noted

that the focus of the cost analysis in this study is on EU-flagged vessels, and an assumption is

made that they spend a large proportion of their time, on average, in EU waters. As such, the

dual – fuel compliance approach is assumed to be less important for these vessels. However, it

is likely that some vessels (in particular, foreign-flagged vessels and internationally EU-flagged

vessels) would not want to incur the additional expense of low sulphur fuel if they didn’t have

to. For these vessels, if they wanted to reduce sulphur by fuel switching, they could either add

an additional fuel storage tank, or split an existing storage tank. Some relevant technical issues

of operating in dual-fuel mode are discussed in Entec's 2002 report for the European

Commission on ship emissions (Entec, 2002).

Therefore this study is considering only the cost to vessels which permanently switch to use

lower sulphur RO, rather than vessels which alternate between fuels with different sulphur

levels. Therefore for the purposes of the cost estimates in this report, it is assumed that it is not

necessary to install an additional fuel tank and associated equipment. In addition, it can be

assumed that there are no significant operating issues associated with switching between fuels

and no capital costs for fuel switching are taken into account.

4.2.2 Operating Costs

Increases in operating costs for fuel switching relate to the premium in fuel costs. Table 4.5

outlines the cost premiums based on the BeicipFranlab report (2003). It can be seen that there is

a wide range of possible price premiums dependant upon supply, fuel demand, production costs

and inherent uncertainties in such estimations especially over a longer time period. The table

also sets out latest estimates from Concawe for fuel price premia (lower for 1.5% and higher for

0.5%). Note that these costs have been corrected for inflation and converted to Euros in year

2000. The specific fuel consumption assumed is 200 g/kWh. This study uses the mid-range

values of the Beicip-Franlab range as the main values, but also presents results calculated with

the Concawe values in brackets ().
Final Report

19

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Table 4.5 Fuel cost premium for low sulphur RO

Fuel switch BeicipFranlab

(2003)

Concawe Main values used

in this study

2.7% S RO-> 1.5% S RO Price premium of fuel (€2000/t) 20 to 80 (30) 50

Specific Premium (€2000/MWh) - - 10

2.7% S RO-> 0.5% S RO Price premium of fuel (€2000/t) 40-88.5 (75) 64

Specific Premium (€2000/MWh) - - 13

2.7% S RO -> 0.2% S MD Price premium of fuel (€2000/t) - - 110

2.7% S RO -> 0.1% S MD Price premium of fuel (€2000/t) - - 130

4.2.3 Total Costs for Fuel Switching

Table 4.6 and Table 4.7 summarise the cost for fuel switching from 2.7% sulphur down to 1.5%

and 0.5% sulphur respectively.

Table 4.6 Total costs, Fuel switching, 2.7 -> 1.5% Sulphur RO (figures in brackets show results

using Concawe price premium)

Vessel

Small Medium Large

Capex (no Capex assumed) 0 0 0

Operating and Maintenance (O&M) costs (€/year) 156,907 513,694 1,282,237

Opex per MWh (€/MWh) 10 10 10

Total annual costs - new build (€/year) 156,907

(94,000)

513,694

(308,000)

1,282,237

(770,000)

Total annual costs - retrofit (€/year) 156,907

(94,000)

513,694

(308,000)

1,282,237

(770,000)
Final Report

20

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Table 4.7 Total costs, Fuel switching, 2.7 -> 0.5% Sulphur RO (figures in brackets show results

using Concawe price premium)

Vessel

Small Medium Large

Capex (no Capex assumed) 0 0 0

Operating and Maintenance (O&M) costs (€/year) 201,737 660,464 1,648,590

Opex per MWh (€/MWh) 13 13 13

Total annual costs - new build (€/year) 201,737

(236,500)

660,464

(773,000)

1,648,590

(1,930,000)

Total annual costs - retrofit (€/year) 201,737

(236,500)

660,464

(773,000)

1,648,590

(1,930,000)
Final Report

21

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

5. Cost Effectiveness

5.1 Cost effectiveness of SO2 abatement techniques for

ships

Table 5.1 and Table 5.2 depict the derived cost effectiveness for the three measures to reduce

SO2 emissions.

Table 5.1 Cost Effectiveness of SO2 Reduction Measures in €/tonne abated (note 1) (figures in

brackets show results using Concawe price premium)

Small Medium Large

Measure New/Retrofit Emission (€/tonne SO2) (€/tonne SO2) (€/tonne SO2)

Sea water scrubbing New SO2 390 351 320

Sea water scrubbing Retrofit SO2 576 535 504

Fuel switching: 2.7% S fuel to 1.5% S fuel New SO2 2,053 (1,230) 2,050 (1,230) 2,045 (1,230)

Fuel switching: 2.7% S fuel to 1.5% S fuel Retrofit SO2 2,053 (1,230) 2,050 (1,230) 2,045 (1,230)

Fuel switching: 2.7% S fuel to 0.5% S fuel New SO2 1,439 (1,690) 1,438 (1,690) 1,434 (1,690)

Fuel switching: 2.7% S fuel to 0.5% S fuel Retrofit SO2 1,439 (1,690) 1,438 (1,690) 1,434 (1,690)

Note 1: Fuel switching costs are based on mid-range value of BeicipFranlab price premia

Table 5.2 Cost Effectiveness of SO2 Reduction Measures in €/tonne fuel used (note 1) (figures

in brackets show results using Concawe price premium)

Small Medium Large

Measure Ship type Unit (€/tonne fuel) (€/tonne fuel) (€/tonne fuel)

Sea water scrubbing New Fuel 16 14 13

Sea water scrubbing Retrofit Fuel 24 22 21

Fuel switching: 2.7% S fuel to 1.5% S fuel New Fuel 50 (30) 50 (30) 50 (30)

Fuel switching: 2.7% S fuel to 1.5% S fuel Retrofit Fuel 50 (30) 50 (30) 50 (30)

Fuel switching: 2.7% S fuel to 0.5% S fuel New Fuel 64 (75) 64 (75) 64 (75)

Fuel switching: 2.7% S fuel to 0.5% S fuel Retrofit Fuel 64 (75) 64 (75) 64 (75)

Note 1: Fuel switching costs are based on mid-range value of BeicipFranlab price premia
Final Report

22

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

5.2 Comparison of cost effectiveness of SO2 abatement

measures for ships compared with SO2 abatement

for other sources

In the context of EU policy development, emissions reductions should be sought where they are

most cost-effective in achieving environmental objectives, taking into consideration all emission

source groups. This section compares the marginal abatement costs of additional abatement

measures for ships with the corresponding costs of additional abatement measures for other

sectors.

The marginal abatement costs of additional abatement measures for all sectors considered in the

CAFÉ modelling work were supplied by IIASA, at the time of undertaking the research for this

study, and represent measures beyond those that are estimated to be implemented under the

CP_CLE scenario, i.e. the measures represent ‘beyond BAU’ measures and are under the

maximum technically feasible reduction scenario – MTFR.

The data is presented in the following figures for SO2. Each figure shows the cost curve for the

specified year, which is comprised of large numbers of individual ‘beyond BAU’ measures

ranked in order of cost effectiveness. The curve starts at the left of each figure, at zero

emissions reduction. As more and more ‘beyond BAU’ measures are taken into account,

emissions are reduced with compliance costs increasing (ie as the cost curve moves to the top

right of the figure).

Each measure represents an individual point on the curve. The slope of the curve indicates the

cost effectiveness at any given point.

Overlaid onto each figure are text boxes and arrows indicating the approximate relative position

in the cost curve where the additional measures for ships considered in this report would fit, if

they were included in the cost curves. It should be noted that the specific measures themselves

are not currently integrated into the cost curves and therefore their impact on remaining

emissions and incremental costs is not explicitly taken into account in the cost curves that are

presented here.

These figures simply enable the relative cost effectiveness of additional measures for ships to be

considered in comparison to the cost effectiveness of ‘beyond BAU’ measures already included

in the RAINS model.

It should be noted that in these figures the fuel switching costs are based on mid-range value of

BeicipFranlab price premia.
Final Report

23

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Figure 5.1 Cost curve for SO2 for 2010 showing position in cost curve where additional

measures for ships would fit (all measures for ships are for medium size vessels)

(Source: IIASA, 2004)

13000

13500

14000

14500

15000

15500

16000

16500

0 500 1000 1500 2000 2500

Emissions reduction (kt)

Total cost (MEuro/yr)

Sea water

scrubbing: new

(medium vessel)

Sea water

scrubbing: retrofit

(medium vessel)

Fuel switching: 2.7%

S fuel to 0.5% S

fuel: new and retrofit

(medium vessel)

Fuel switching: 2.7%

S fuel to 1.5% S fuel:

new and retrofit

(medium vessel)
Final Report

24

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Figure 5.2 Cost curve for SO2 for 2020 showing position in cost curve where additional

measures for ships would fit (all measures for ships are for medium size vessels)

(Source: IIASA, 2004)

12500

13000

13500

14000

14500

15000

15500

16000

16500

0 200 400 600 800 1000 1200 1400 1600

Emissions reduction (kt)

Total cost (MEuro/yr)

Sea water

scrubbing: new

(medium vessel)

Sea water

scrubbing: retrofit

(medium vessel)

Fuel switching: 2.7%

S fuel to 0.5% S

fuel: new and retrofit

(medium vessel)

Fuel switching: 2.7%

S fuel to 1.5% S fuel:

new and retrofit

(medium vessel)

It is evident that the potential additional measures for SO2 for ships are spread along the cost

curve: sea water scrubbing being one of the more cost-effective measures on the left of the cost

curve, whereas fuel switching is positioned further towards the right.

For further comparison, the indicative average marginal abatement costs supplied by IIASA for

sectors in the RAINS model with ‘beyond BAU’ SO2 measures are shown in Table 5.3. This

includes all RAINS sectors except the shipping sector, due to the more specific ship emissions

abatement estimates derived in this study. Within each sector in the table, the quoted marginal

abatement cost represents an average across all fuel types, abatement techniques and countries.

Hence, individual measures may differ significantly from the quoted figures.
Final Report

25

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Table 5.3 Indicative average marginal abatement costs for sectors with ‘beyond BAU’ SO2

measures supplied by IIASA for 2010 and 2020

Sector 2010 Cost Curve -

marginal cost

(Euro/t)

2020 Cost Curve -

marginal cost

(Euro/t)

Fuel production & conversion: Combustion 2704 2704

Combustion in residential-commercial sector 2004 2004

Industry: Combustion in boilers 5609 6445

Industry: Other combustion 2139 2627

Power & district heat plants: Exist. other 3838 4365

Power & district heat plants: New 8946 8659

Industrial. Process: Cement production 8691 8691

Industrial. Process: Coke oven 1144 1144

Industrial. Process: Lime production 5839 5839

Industrial. Process: Other non-ferrous metals prod. - primary and secondary 2786 2786

Industrial. Process: Pig iron, blast furnace 1083 1083

Industrial. Process: Paper pulp mills 1099 1099

Industrial. Process: Petroleum refineries 1070 1070

Industrial. Process: Agglomeration plant - sinter 941 941

Industrial. Process: Sulfuric acid 972 990

Other transport: rail (solid fuels), heating (stationary combustion) 5245 5245

Waste: Agricultural waste burning 686 686

Waste: Flaring in gas and oil Industry 6286 6747

Waste: Open burning of residential waste 1586 1586

It can be seen from a comparison of Table 5.3 with Table 5.1, that the shipping sector is one of

the more cost effective sectors (per tonne SO2 abated) for achieving additional ‘beyond BAU’

SO2 emissions reductions, with sea water scrubbing being a particularly cost-effective technique

relative to other techniques in the cost curve.

It is emphasised, however, that whilst the potential position of a measure in a single-pollutant

cost curve is a useful gauge of its relative cost-effectiveness, it is not necessarily indicative of its

relative cost-benefit performance, due to the generally greater distance of ship emission sources

to nearest receptor populations and environments.

The scope of this particular study does not extend to a cost-benefit analysis, however this would

be important in any further policy development related to potentially tighter standards in the

shipping sector. If such work was to be done, it would clearly be necessary to consider the costs

in more detail (including relevant wider economic impacts) and to quantify the health and

environmental benefits of any potential emissions reductions (including impacts on other

pollutants). In such an analysis, the location of ship emissions relative to receptor populations

and environments would need to be taken into account.
Final Report

26

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554
Final Report

27

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

6. Scale up for all EU-Flagged Ships

As mentioned in the General Report only commercial ships > 500 GT are included in this study.

Assumptions on numbers of existing ships in the EU-flagged fleet and the world fleet are shown

in Table 6.1.

Table 6.1 Number of ships in the EU-flagged and world fleet

Number of EU-flagged vessels >500GT 7,150

Number of ships in world fleet >500GT 31,000

The costs for applying the technologies to the EU-flagged fleet are shown in Table 6.2. This

table illustrates costs per year for applying each measure to all applicable existing ships. The

additional costs per year for each new build ship are presented in Section 4 for each abatement

measure.

Table 6.2 Costs for applying measures to existing vessels in the EU-flagged fleet (estimates

based on CONCAWE fuel prices in brackets)

Vessels Total

Small Medium Large

Fraction of total EU-flagged ships 55% 35% 10% 100%

SWS, annualised costs for retrofitting all existing

ships (€millions/year)

292 566 381 1,239

Fuel switching, annualised costs for switching to

1.5% S fuel for all existing ships (€millions/year)

617 (370) 1,285 (770) 917 (550) 2,819

(1,690)

Fuel switching, annualised costs for switching to

0.5% S fuel for all existing ships (€millions/year)

793 (930) 1,653 (1,940) 1,179 (1,380) 3,624

(4,250)
Final Report

28

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554
Final Report

A1

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Appendix 1

Pride of Kent Trials Air and Water Emission

Monitoring Reports

Table of Content

1. DME Project 1497 June 2004

2. November 2004 Test Results Summary
Final Report

A2

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

1. DME Project 1497 June 2004

CONTENTS

SECTION DESCRIPTION

1 PROJECT OVERVIEW

2 SUMMARY OF TEST RESULTS

3 METHODOLOGY

3.1 Sampling Procedures
Final Report

A3

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

1. PROJECT OVERVIEW

DME (Marine Exhaust Solutions) of Charlottetown Canada contracted Air Quality Solutions

to conduct an emission measurement programme on their installation on board the P & O

Ferry ‘Pride of Kent’ based from Dover England.

The installation performs exhaust gas scrubbing for SO2 removal direct from the diesel engine

exhaust gases.

The emission tests were carried out from the 1

st

June until the 3

rd

June 2004. Velocity tests

were carried out on the 15

th

June 2004.

The purpose of the test programme was to measure actual air emissions from inlet and outlet

locations in accordance with DME requirements.

The test source was identified as follows:

• Stack (Inlet/Outlet)

The test programme included the determination of the following emissions:

• SO2

• NOx

Co-ordinating the field testing were:

Mr Chris Skawinski Marine Exhaust Solutions (DME)

Mr Chris Green Air Quality Solutions

The results of the tests are summarised in section 2.
Final Report

A4

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554
Final Report

A5

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

2. SUMMARY OF TEST RESULTS

Calibration of each analyser system was carried out daily before and after each test.

Date Location Comment

01/06/04 Inlet Outlet Preliminary Data

02/06/04 Inlet Outlet Validation Test

03/06/04 Inlet Outlet Process adjustment response

15/06/04 Outlet(s) Velocity Tests

Fuel: Heavy Fuel 2.4% Sulphur

Location: Auxiliary

Test No:

*Engine

Load (kW)

*Water Level

PID (mm)

*Backpressure

Range

(mmH2O)

SO2

(Avg)

NO/NOx

(Avg)

Validation test,

14:00-15:00

inlet 625 250 280-300 526.0 1008.1

outlet 625 250 280-300 31.9 972.6

Validation test

14:00-16:30

inlet 625 250 280-300 526.0 1008.1

outlet 625 250 280-300 45.8 976.8

*Operating details provided by DME
Final Report

A6

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

DME Comparison Inlet Outlet.xls

inlet weds (2)am.xls

inlet weds am.xls

inlet weds pm.xls

outlet weds pm.xls

Calibration Check Thursday (Inlet).xls

Calibration Check Thursday (Outlet).xls

DME Velocity Data.xls

Conclusions

• Test duration 150 minutes

• Data logged @ 15 second intervals

• Average SO2 value before scrubbing 526.0ppm

• Average SO2 value after scrubbing 45.8ppm

• Best average continuous rate of SO2 removal 94 %

• Best maximum continuous rate of SO2 removal 95.1%

• Worst average continuous rate of SO2 removal 91%

• NOx average removal rate: 2%

Comment

Inlet/outlet SOx and NOx monitoring conducted at the same time during the test.
Final Report

A7

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Sampling Locations
Final Report

A8

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Typical Equipment Set Up
Final Report

A9

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

3 METHODOLOGY

3.1 Sampling Procedures

The sample gas was extracted from the scrubber inlet and outlet ducts as requested via a

filtered/heated sample system into a gas conditioning system to remove moisture, the resulting

dry gas was than transferred to the Horiba PG 250 analyser system and data logger,

measurements were recorded at 15 second intervals.

Equipment List

• G212 Gas sample probe (2 off)

• H311 Heated sample line (2 off)

• GC03 Gas conditioning/flow control system (2 off)

• 12418 Horiba PG 250 (2 off)

• DRM 3 Data Logger (2 off)

• SB003 Stack Kit

• SB004 Stack Kit

3.2 November 2004 Test Results Summary

Test Results for Marine Exhaust Solutions EcoSilencers for auxiliary motors

onboard the Pride of Kent.

November 2004

Independent Testing by: Westech

54 Hillstrom Avenue • Charlottetown

Prince Edward Island • CANADA C1E 2C6

TEL: 902.628.6900

FAX: 902.628.1313

MARINE EXHAUST SOLUTIONS INC.
Final Report

A10

h:\projects\em-260\13000 projects\13554 pp ship emissions\reports\task 2 final

report\task 2 so2 final_final report 16_09_05v2.doc

August 2005

13554

Test Date EcoSilencer

Unit

% SO2

removed

Equivalent %SO2

fuel rating *

Comments

24 Nov 2004 Auxiliary motors

Stbd Inner 68% - 74% 0.8% - 0.65%

3 Auxiliary units on line & under

load

25 Nov 2004 Auxiliary motors

Stbd Inner 76% - 80% 0.6% - 0.5%

1 Auxiliary units on line & under

load

26 Nov 2004 Auxiliary motors

Port Outer 76% - 80% 0.6% - 0.5%

2 Auxiliary units on line & under

load

*Based on nominal bunker sulphur content of 2.5%.