a life cycle cost analysis of marine scrubber technologies shih-tung (emship... · cost analysis is...

A Life Cycle Cost Analysis of Marine Scrubber Technologies

Shih-Tung Shu

Master Thesis

presented in partial fulfillment of the requirements for the double degree:

“Advanced Master in Naval Architecture” conferred by University of Liege "Master of Sciences in Applied Mechanics, specialization in Hydrodynamics,

Energetic and Propulsion” conferred by Ecole Centrale de Nantes

developed at University of Rostock, Rostock in the framework of the

“EMSHIP” Erasmus Mundus Master Course

in “Integrated Advanced Ship Design”

Ref. 159652-1-2009-1-BE-ERA MUNDUS-EMMC

Supervisor: Prof. Robert Bronsart, University of Rostock, Rostock, Germany.

Reviewer: Dr. Tomasz Urbanski, West Pomeranian University of

Technology, Szczecin, Poland.

Rostock, February 2013

A Life Cycle Cost Analysis of Marine Scrubber Technologies i

“EMSHIP” Erasmus Mundus Master Course, period of study September 2011 – February 2013

ABSTRACT

MARPOL Annex VI regulates the emissions from all ships trading internationally. Ship

owners must take actions before the lowest limits come into force. The combined challenges

of rising oil prices and increasing regulatory stringency on shipping’s air emissions justify the

exploration of feasibilities between compliant technologies. This study focuses on the

scrubber technology for large marine engines with which ships can continue to use preferable

cheap heavy fuel oil (HFO) without exceeding the emission control limits. It draws on

existing technical and economical information about scrubber systems in the market to

establish a complete life cycle cost analysis for four vessel types: Containership, passenger

ship, Ro-Pax and tanker.

An investigation of the technology overview, cost data, emission reduction efficiency, impact

of installations, operational issues and installation case studies is conducted. Environmental

impacts such as wash water discharge, sludge disposal and end-of-life recycling are also

addressed. By choosing the marine gas oil (MGO) utilisation as the baseline, the life cycle

cost analysis is performed between different types of scrubber system, namely open loop

seawater scrubber, closed loop freshwater scrubber, hybrid scrubber and dry scrubber system.

The life cycle cost analysis results are presented by the net present value (NPV) and the return

of investment (ROI) time. Under the assumption of current HFO and MGO price, a positive

NPV can be found for every scrubber types subjected to four vessel types with the ROI time

ranging from 1to 5 years depending on the operation profile in ECA-SOx.

Keyword: Life cycle cost analysis, MARPOL Annex VI, scrubber technology, emission

control areas, exhaust gas treatment technology, SOx abatement , NOx abatement

ii Shih-Tung Shu

Master Thesis developed at University of Rostock, Germany

CONTENTS

LIST OF FIGURES VI

LIST OF TABLES VIII

ABBREVIATIONS IX

1. INTRODUCTION 1

1.1. OBJECTIVES 2

1.2. LEGISLATIVE FRAMEWORK 3

1.2.1. MARPOL Annex VI 3

1.2.2. The United States Marine Emission Standards 5

1.3. LITERATURE REVIEWS 7

1.3.1. Abatement Technologies Related 7

1.3.2. Life Cycle Cost Analysis Related 10

1.3.3. Installation of Abatement Technologies Related 12

1.3.4. Other Literature Reviews 14

2. LIFE CYCLE COSTING 15

2.1. THEORY AND APPLICATIONS 16

2.2. PRINCIPLES AND PURPOSES 17

2.2.1. Cost 17

2.2.2. Time 17

2.2.3. Discount Rate 17

2.2.4. LCCA Procedure 18

2.3. SCRUBBER SYSTEM PROJECT DESCRIPTION 20

3. EXHAUST GAS TREATMENT TECHNOLOGIES OVERVIEW 21

3.1. SULFUR OXIDE (SOX) ABATEMENT TECHNOLOGIES 21

3.1.1. Wet Scrubbers 21

3.1.2. Dry Scrubbers 25

3.2. NITROGEN OXIDE (NOX) ABATEMENT TECHNOLOGIES 28

3.2.1. Primary NOx control 28

3.2.2. Secondary NOx Control 32

3.3. PARTICULATE MATTER (PM) ABATEMENT TECHNOLOGIES 34

3.3.1. Diesel Particulate Filter (DPF) 35

A Life Cycle Cost Analysis of Marine Scrubber Technologies iii


3.3.2. Diesel Oxidation Catalyst (DOC) 36

3.3.3. Electrostatic Precipitator (ESP) 36

3.4. SUMMARY 38

4. OPERATIONAL ISSUES AND CASE STUDIES 40

4.1. WET SCRUBBER SYSTEM 40

4.1.1. Scrubber Unit 40

4.1.2. Pumping System 42

4.1.3. Piping System 42

4.1.4. Sludge Tank 43

4.1.5. NaOH Dosing and Storage System 43

4.1.6. Bleed-off and Fresh Water Topping System 44

4.2. DRY SCRUBBER SYSTEM 45

4.2.1. Scrubber Unit 45

4.2.2. Granulate Conveying System and Power Consumption 47

4.2.3. Granulate Consumption Rate 47

4.2.4. Granulate Logistic and Recycling 48

4.3. SELECTIVE CATALYST REACTION (SCR) 49

4.3.1. SCR Reactor 49

4.3.2. Catalyst Block Elements 51

4.3.3. Urea Consumption and Storage 52

4.3.4. Soot/ash Blowing System 52

4.4. TECHNOLOGIES COMPARISON 53

4.5. CASE STUDIES 56

4.5.1. MS Pride of Kent – SWS system 58

4.5.2. MS Zaandam– SWS system 59

4.5.3. MT Suula– FWS system 60

4.5.4. Ficaria Seaways – HS system 61

4.5.5. SCR System Installation 63

5. INSTALLATION IMPACTS 65

5.1. TECHNICAL IMPACTS 65

5.1.1. Space 65

5.1.2. Weight 66

iv Shih-Tung Shu


5.1.3. Operation Mode 66

5.1.4. Chemical Usage 67

5.1.5. Exhaust Gas Handling 68

5.1.6. Noise Attenuation 70

5.1.7. Crew Training 71

5.2. ENVIRONMENTAL IMPACT 72

5.2.1. Washwater Discharge Criteria 72

5.2.2. Sludge Disposal 72

5.2.3. Scrubber End-of-life 73

6. LIFE CYCLE COST ANALYSIS 75

6.1. BASELINE SCENARIO 76

6.2. LCCA FRAMEWORK 77

6.2.1. Capital Expenditures 77

6.2.2. Operational and Maintenance Expenditures 79

6.2.3. End-of-life Expenditures 81

6.2.4. Fuel Escalation and Inflation 81

6.3. TECHNOLOGIES COMPARISON 84

6.4. SENSITIVITY ANALYSES 90

6.4.1. Fuel Price Sensitivity 90

6.4.2. Fuel Escalation and Inflation Rate Sensitivity 91

6.4.3. Engineering Design and Installation Sensitivity 91

6.4.4. Labour Cost Sensitivity 92

6.4.5. Worst and Best Combination Sensitivity 92

6.5. DISCUSSION 94

7. CONCLUSION 95

ACKNOWLEDGEMENTS 98

REFERENCES 99

APPENDIX – SCR LIFE CYCLE COSTING 102

A Life Cycle Cost Analysis of Marine Scrubber Technologies v


DECLARATION OF AUTHORSHIP

I declare that this thesis and the work presented in it are my own and have been generated by

me as the result of my own original research.

Where I have consulted the published work of others, this is always clearly attributed.

Where I have quoted from the work of others, the source is always given. With the exception

of such quotations, this thesis is entirely my own work.

I have acknowledged all main sources of help.

Where the thesis is based on work done by myself jointly with others, I have made clear

exactly what was done by others and what I have contributed myself.

This thesis contains no material that has been submitted previously, in whole or in part, for

the award of any other academic degree or diploma.

I cede copyright of the thesis in favour of the University of Rostock, Rostock, Germany.

Date: 13.01.2013 Signature

vi Shih-Tung Shu


LIST OF FIGURES

Figure 1. Regulation 14 SOx limits 3

Figure 2. Regulation 13 NOx limits 5

Figure 3. Categories of LCC 15

Figure 4. Steps of LCCA 18

Figure 5. A open loop SWS system [Lloyd’s Register 2012] 23

Figure 6. A closed loop FWS system [Lloys’s Register 2012] 24

Figure 7. A HS system operating in open loop mode [Lloys’s Register 2012] 25

Figure 8. A HS system operating in closed loop mode [Lloys’s Register 2012] 25

Figure 9. A dry scrubber system [Couple System] 26

Figure 10. An EGR system [MAN Diesel & Turbo] 31

Figure 11. A SCR system [Jürgens R, 2011] 32

Figure 12. PM penetration efficiency. 34

Figure 13. An ESP system. 37

Figure 14. Weight of wet scrubber system 41

Figure 15. Volume of wet scrubber system 41

Figure 16. NaOH consumption rate [Wärtsilä 2011] 44

Figure 17. Weight of dry scrubber system 46

Figure 18. Volume of dry scrubber system 46

Figure 19. Weight of SCR system 49

Figure 20. Volume of SCR system 49

Figure 21. SCR operation temperature [Wärtsilä 2011] 50

Figure 22. Catalyst block fouling [Lloyd’s Register, 2012] 51

Figure 23. MS Pride of Kent. 58

Figure 24. MS Zaandam. 59

Figure 25. MT Suula. 60

Figure 26. Ficaria Seaways. 62

Figure 27. Total engine power of SCR installation 63

Figure 28. Number of SCR installation 63

Figure 29. Single and multi-inlet scrubber system 69

Figure 30. Abatement technology compatability 70

Figure 31. Cost information of scrubber system 77

A Life Cycle Cost Analysis of Marine Scrubber Technologies vii


Figure 32. NPC and ROI of vessel/route 1 – Containership 85

Figure 33. NPC and ROI of vessel/route 2 – Passenger ship 86

Figure 34. NPC and ROI of vessel/route 3 - Ro-ro Ferry 87

Figure 35. NPC and ROI of vessel/route 4 - Tanker ship 88

Figure 36. SCR CapEx estimation 103

viii Shih-Tung Shu


LIST OF TABLES

Table 1. U.S. EPA marine engine categories. 5

Table 2. Advanced IEM combinations [Ritchie A. et al., 2005] 29

Table 3. SOx, NOx and PM abatement technologies 38

Table 4. Main components of wet scrubber systems 40

Table 5. Comparison of wet and dry scrubber system components 45

Table 6. Comparison of scrubber systems 53

Table 7. List of scrubber installations 57

Table 8. Comparison of multiple separate and multi-inlet scrubber system 69

Table 9. Close loop wet scrubber sludge sampling [Kjølholt J. et al, 2012] 73

Table 10. Baseline of four vessel types 76

Table 11. Scrubber equipment cost 78

Table 12. Capital expenditures and cost items 78

Table 13. O&M expenditures and cost items 79

Table 14. Wet scrubber system parameters 82

Table 15. Dry scrubber system parameters 83

Table 16. LCCA results of vessel/route 1 - Containership 85

Table 17. LCCA results of vessel/route 2 - Passenger ship 86

Table 18. LCCA results of vessel/route 3 - Ro-Pax ship 87

Table 19. LCCA results of vessel/route 4 - Tanker ship 88

Table 20. Fuel price sensitivity 90

Table 21. Fuel escalation and inflation rate sensitivity 91

Table 22. Engineering design and installation sensitivity 92

Table 23. Labour cost sensitivity 92

Table 24. Worst and best combination sensitivity 92

Table 25. SCR cost estimation data collection 102

Table 26. SCR CapEx estimation 103

Table 27. LCC of SCR system installation 104

A Life Cycle Cost Analysis of Marine Scrubber Technologies ix


ABBREVIATIONS

CapEx Capital Expenditures

DWI Direct water injection

ECA Emission control area

ECA-Nox Nitrogen Emission control area

ECA-SOx Sulphur Emission control area

EGC Exhaust gas cleaning

EGR Exhaust gas recirculation

EGT Exhaust gas treatment

ESP Electrostatic Precipitator

FWS Freshwater scrubber

GRE Glass reinforced epoxy

HAM Humid air motor

HC Hydrocarbon

HERCULES Project of Higher-Efficiency Engine with Ultra-Low Emissions for

Ships

HFO Heavy fuel oil

HS Hybrid system

IEM In engine modification

IMO International Maritime Organization

LCC Life cycle cost

LCCA Life cycle cost analysis

LNG Liquidized natural gas

MARPOL The International Convention for the Prevention of Pollution From

Ships (MARine POLlution)

MCR Maximum continuous rating

MEPC Marine Environment Protection Committee

MGO Marine gas oil

MW Megawatt

NOx Nitrogen oxides

NPC Net present cost

NPV Net present value

x Shih-Tung Shu


O&M Operation and Maintenance Expenditures

PAH Polycyclic aromatic hydrocarbons

PCB Polychlorinated biphenyls

PM Particulate matter

ROI Return of investment

S Sulphur

SCR Selective Catalytic Reduction

SFOC Specific fuel oil consumption

SOx Sulphur oxides

SWS Seawater scrubber system

THC Total petroleum hydrocarbons

U.S. EPA Environmental Protection Agency of the United States

VOC Volatile organic compounds

A Life Cycle Cost Analysis of Marine Scrubber Technologies 1


1. INTRODUCTION

Air pollution can cause discomfort, diseases, health damage and even death to humans.

Regulations and emission controls are currently one of the most important issues worldwide.

In response to growing concerns about air quality, pollutions and its environmental

consequences from the seaborne traffics, initiatives, measurements and regulations are

introduced through International Maritime Organization (IMO). Reduction of air emissions

with respect to sulphur dioxide, nitrogen oxide and particulate matter is addressed and

regulated through MARPOL amendment protocol in 1997.

MARPOL Annex VI regulates the emissions from all ships trading internationally. Ship

owners must take actions before the lowest limits come into force. There are several

alternatives available in the market, namely marine gas oil (MGO), liquidised natural gas

(LNG), shore-side electricity, fuel switching, exhaust gas treatment (EGT) technologies et

cetera. Each of the technologies will have various technical and economical impacts on ships

as well as the shipping industry and investments will be required in any case. The combined

challenges of rising oil prices and increasing regulatory stringency on shipping’s air emissions

justify the exploration of feasibilities between technologies.

Using low sulphur content fuel instead of heavy fuel oil (HFO) is the simple quick solution

with regard to the limit for sulphur content in marine fuel. However, due the production

complexity and availability of low sulphur fuel, there is a clear risk that low sulphur fuel will

not be the solution for all ships when the global sulphur cap comes by year 2020.

Scrubber system is one of the exhaust gas treatment (EGT) technologies, with which ships

can continue to use preferable cheap HFO without exceeding SOx emission control limits,

draws attentions among the shipping industry. Scrubber system has been a proven technology

for land-based applications, but there are still concerns about the maturity of marine scrubber

technology and seaborne application with limited space onboard and the challenge of different

engine load.

In order to make a good decision with regard to the long term investment, it is essential to

understand sufficient detail of environmental impact, technical feasibilities and life cycle cost

2 Shih-Tung Shu


of scrubber system installations. Most of the literature reviews focus on the capital

expenditure, while the impacts of operational cost and end of life disposal are either ignored

or roughly estimated. To explore further, the study aims at the cost data from literature studies

and information from scrubber vendors and an assessment study for decision making is

provided to establish a complete life cycle cost analysis (LCCA) for four vessel types:

Containership, passenger ship, Ro-Pax and tanker. .

1.1. Objectives

The specific objectives of the study and assessments of scrubber installation are presented as

followed:

1. Introduce the terminology of life cycle cost analysis with clear principles and steps.

2. Provide an introduction of MARPOL Annex VI compliance alternative technologies and

an overview of exhaust gas treatment (EGT) technologies.

3. Assess the possible technical and environmental impacts of scrubber system installation.

4. Quantify the weight loss of a scrubber installation.

5. Present case studies of the scrubber installations.

6. Assess the possible economical impacts by LCCA with a return of investment (ROI)

comparison between different scrubber systems and sensitivity analyses which give

previews of future uncertainties.



1.2. Legislative Framework

1.2.1. MARPOL Annex VI

The International Convention for the Prevention of Pollution from Ships, known as MARPOL

for Marine Pollution, was adopted by International Maritime Organization (IMO) in 1973.

The MARPOL Convention addresses pollution from ships by oil; by noxious liquid

substances carried in bulk; harmful substances carried by sea in packaged form; sewage,

garbage; and the prevention of air pollution from ships, which has greatly contributed to a

significant decrease in pollution from international shipping. Annex VI was added to regulate

the air emissions through MARPOL amendment protocol in 1997, which entered into force in

2005 and significant amendments were made in 2008.

SOx emission control

SOx Emission Control Areas (ECAs-SOx) are introduced to further limit the air emission in

certain areas. Currently there are four approved ECAs-SOx regions including the Baltic Sea,

the North Sea, the North American ECA-SOx – 200 nautical miles offshore U.S.A. and

Canada, including Hawaii, St. Lawrence Waterway and the Great Lakes (as from 1st August

2012) and the United States Caribbean Sea ECA-SOx (as from 1st January 2014).

Regulation 14 of MARPOL Annex VI puts the limits on the sulphur content of fuel to restrict

SOx and particulate matter emissions. It is valid for all the ships in service worldwide inside

and outside ECAs for specified limit, which is a stepped reduction over time, as shown in

Figure 1.

Figure 1. Regulation 14 SOx limits

4 Shih-Tung Shu


Currently inside ECAs-SOx, only fuels with 1.50% sulphur content can be used, while as

from 1st January 2015, MARPOL Annex VI will require that the maximum sulphur content in

fuels used by ships inside ECAs-SOx to be of 0.10% by weight. Outside ECAs-SOx, a

maximum sulphur content of 3.50% fuels can be used now and will be lowered to 0.50% by

weight either on 1st January 2020 or 1st January 2025 based on a final decision in 2018 to be

taken by IMO’s Marine Environment Protection Committee (MEPC) depending on the

outcome of as review of fuel oil availability.

Regulation 4 allows alternative technologies to be used, like SOx scrubber systems to ensure

a similar limitation of SOx emissions while using a fuel with sulphur content higher than that

allowed by Regulation14 as equivalent means of compliance. Flag administrations have to

approve the use of scrubber systems as compliant in accordance with the IMO Exhaust Gas

Cleaning Systems Guidelines (MEPC 184(59) – 2009 Guidelines for Exhaust Gas Cleaning

Systems).

MEPC 184 (59) specifies two schemes of certification and verification where Scheme A

compliance of SOx scrubbers means initial approval and certification of performance

followed by in-service continuous monitoring of operating parameters with daily checking of

SO2/CO2 emission ratio and for Scheme B compliance of SOx scrubbers a continuous

emissions monitoring system of SO2/CO2 emission ratio with in-service daily spot checks of

operating parameter is required.

NOx emission control

Regulation 13 restricts NOx emissions of marine diesel engines. Unlike SOx emission control

limits all ships depending on the region travelled, it divides the engines into three “Tiers”

depending on the date of ship construction or the date of installation of additional or non-

identical replacement engines and the engine’s rated speed, as shown in Figure .

IMO requires ships built on or after 1st January 2000 to meet Tier I emissions levels. Ships

built on 1st January 2011 or later must meet the Tier II standard. For Tier III, ship constructed

on or after 1st January 2016 sailing inside and outside ECA-NOx will have two specified

limits respectively. Currently there are two ECAs-NOx, namely the North American ECA-

NOx and the United Stated Caribbean ECA-NOx regions, which will be in effect in 2016.



Figure 2. Regulation 13 NOx limits

Resolution MEPC 177(58) of NOx Technical Code adopted in 2008 contains mandatory

procedures for the testing, survey and certification of marine diesels.

1.2.2. The United States Marine Emission Standards

All the vessels flagged of registered in the United States or vessels operating in U.S. waters

must follow the U.S. federal regulations as per the Act to Prevent Pollution from Ships. U.S.

Environmental Protection Agency breaks the diesel powered compression engines into three

different categories based on displacement (swept volume) per cylinder as shown in Table 1

(available from http://www.dieselnet.com/standards/us/marine.php [Accessed 6 January

2013]). Each category represents a different engine technology.

Table 1. U.S. EPA marine engine categories. Category Displacement per Cylinder (D) Basic Engine Technology

Tier 1-2 Tier 3-4

1 D < 5 dm3* D < 7 dm3 Land-based non-road diesel

2 5 dm3 ≤ D < 30 dm3 7 dm3 ≤ D < 30 dm3 Locomotive engine

3 D ≥ 30 dm3 Unique marine engine design

*And power ≥ 37 kW

Ocean-going vessels such as container ships, oil tankers, bulk carriers, and cruise ships using

category 3 marine engine, typically range in size from 2,500 to 70,000 kW, must meet the

6 Shih-Tung Shu


equivalent standards to IMO MARPOL Annex VI. Further regulations on category 3 engines

regarding PM, HC and CO control are being finalized by U.S. EPA. As stated in the U.S.

Emission Standard website: http://www.dieselnet.com/standards/us/marine.php, a HC

emission standard of 2.0 g/kWh and a CO standard of 5.0 g/kWh from new Category 3

engines are adopted. No emission standard was adopted for PM, but manufacturers are

required to measure and report PM emissions.



1.3. Literature Reviews

1.3.1. Abatement Technologies Related

The stringent MARPOL regulations of seaborne air emission reduction have raised ship

owners’ attentions to Exhaust Gas Treatment (EGT) systems. Onshore EGT systems for

vehicles and power plants have been developed and used in a wide range of applications over

the past two decades, while the marine EGT applications are relatively new to their users. The

typical concerns are the reduction efficiency, cost of EGT systems and compliant alternative

for MARPOL regulations.

Many impact assessment studies have contributed to provide a better understanding of the

modern marine EGT systems and the economical impacts. One of the earliest impact

assessment studies was conducted by Ritchie A. et al. (2005). The study investigated the cost,

emission reduction potential and practicalities of ship emission abatement technologies. The

report mainly focused on a number of general assumptions and methods utilized to estimate

the costs and emission reduction results. It also summarized the efficiencies of abatement

technologies considering the maturity of technologies and their estimated “business as usual”

uptake. The quantifications of reduction efficiencies and costs per kilowatt for different

abatement technologies have provided good technical references for future abatement

equipment studies.

Later on in 2009, Bosch P. et al. conducted a cost benefit analysis for supporting the impact

assessment accompanying the revision of Directive 1999/32/EC on the Sulphur Content of

certain liquid fuels. The study assessed the effects, costs, risks and technical requirements that

are associated with the use of emission abatement equipment (SOx and NOx) by ships. Costs

of new and retrofit abatement technologies were estimated. Some data from the report

conducted by Ritchie A. et al. (2005) are used as reference. The estimation provided different

scenarios using 1.5, 0.5 and 0.1% sulphur content in fuel. Furthermore, it discussed the IMO

technical criteria for exhaust abatement equipments, such as pH, PAH, turbidity issues for

wash water discharge. It concluded that the use of scrubbers may be an economically

attractive option in Sulphur Emission Control Areas (SECAs) and also worldwide from 2020,

while the measures should be taken to assure that the marine environment is protected.

8 Shih-Tung Shu


Meanwhile, Stavrakaki A. et al. (2009) proposed an impact assessment for the revised Annex

VI of MARPOL. The appendix summarized six reports regarding revision of MARPOL

Annex VI including interviews with two scrubber vendors. Cost data analysis, collected from

various data sources, was made to compare with different categories of vessel and engine size.

Capital, operating and annualized costs of scrubber per vessel are presented in the summary

table,

Kalli J. et al (2010) conducted a quantitative estimation of the additional costs of the Baltic

ECAs focusing on the NOx abatement technologies. It stated that SCR is the only technology

available today which meets MARPOL tier III reduction requirements and from which there

is enough information to make the cost estimates. Cost calculations in the study showed that

NOx abatement will cost 2,585 to 15,440 Euros per abated tonne of nitrogen depending on the

type of a ship and the method of calculation, while the average cost is about 4,325 to 6,059

Euros per tonne of nitrogen. In the conclusion, it noted that the potential for modal shift from

sea transport to road or rail transport caused solely by the NOx regulations will be very small

or non-existent.

Rather than focusing only on the economical sides, the ecological and environmental issues

were also considered and discussed after various cost estimations have been made since 2005.

Grebot B. et al. (2010) proposed a study to review assessments undertaken of the revised

MARPOL Annex VI regulations. The study’s purpose was to draw together the conclusions

of six independent reports about the potential impacts of the revised MARPOL Annex VI

regulations on sulphur emissions on the maritime sector. The average increase in fuel cost per

ton was estimated to be of around 80%. The cost of alternative compliance such as seawater

scrubber was expected to be 20 to 50 % of the total cost of switching fuels. However, it

indicated that some concerns have been raised regarding the uncertainties related to the

availability and reliability of this novel technology. Challenges of for instance, ecological and

environmental concerns of sludge disposal, availability of space on vessel, interaction with

other abatement measure such as selective catalytic reduction, fuel consumption penalty and

uncertainty over costs and technology have to be faced and solved.

In 2011, the market for EGT systems has developed over time and there are more and more

EGT system suppliers. Jürgens R. et al (2011) proposed a state of the art and efficiency report



which gave detailed abatement technology overview and vendors’ information. Seven

scrubber manufacturers were introduced with system efficiency trial results, waste streams,

system details and system description provided by the supplier. Particulate precipitations

inside wet scrubber, dry scrubber and SCR systems were discussed. It noted that Abatement

technology should not only clean up the emissions, but also the obligation to not interfere

with the performance of the engine.

One of the major engine manufacturers and EGT system supplier (Wärtsilä, 2011) provided a

product guide containing data and system proposals for the early design phase of marine

abatement installations. Technical data and configurations of wet scrubber systems and SCR

technology were presented and indicated the size and weight of the systems, sludge

generation, washwater flow rate, NaOH consumption rate and urea consumption rate.

Even though EGT systems regarding SOx abatement have gained more experience via several

pilot testing projects, there are still concerns about practical operations. Intertanko (2012)

published a guidance published in July covering the review of the regulatory regime,

alternatives for compliance, the advantages and challenges of the alternatives for compliance

and details on operational and safety aspects of scrubbers. Marine gas oil, liquefied natural

gas and exhaust gas treatment systems were introduced for the alternative options for

compliance. It was mentioned that LNG is not yet a practical option except in special cases

when subsidies were given for covering part of the retrofitting expenses and it may become an

option for future new buildings in accordance with the global sulphur cap. The challenges for

exhaust gas treatment systems were listed and an ECA calculator was also presented to

estimate the cost-efficient alternative to comply with (MGO or scrubbers) as a function of

ship’s life span with the estimation time spent in ECAs.

Lloyd’s Register (2012) also published a guideline for ship owners and operators. The

guideline provided a general overview of regulations and technologies. SOx scrubbers and

NOx reducing devices are introduced as the exhaust gas treatment systems (EGTs). Two NOx

reducing devices were noted, namely SCR and EGR to address their potential and availability

for lowering the NOx emissions under the limit in accordance with the Tier III rules. The

issues of installing EGTs such as the risk, backpressure, and maintenance have also been

pointed out with. It was very comprehensive for readers to understand from the statutory

regulations to the comparisons between different scrubber technologies through the clear

10 Shih-Tung Shu


introduction to the state of the art and the case studies of SOx scrubber onboard the ferry ship

Pride of Kent and Ficaria Seaways, which provides empirical scrubber installation.

1.3.2. Life Cycle Cost Analysis Related

Life cycle cost analysis is a powerful method for calculating costs incurred throughout a

product’s life. It became popular in 1960s as an instrument to ensure the cost effectiveness of

purchasing any equipment. The theory and procedures of LCCA evolved over time and it is

now applied to various engineering projects. In 1997, Woodward published a paper

summarizing several LCCA procedures. The LCCA terminology including the elements of

LCC, methodologies to determine discount rate, definitions of operating, maintenance and

disposal cost is introduced. He addressed the importance of performing sensitivity analysis to

consider uncertainties in the future. Key factors such as cost, time, trade-off, financial

functions and organisational functions should be highlighted in a LCCA. In the conclusion,

LCC is defined as “a concept which aims to optimise the total costs of asset ownership, by

identifying and quantifying all the significant net expenditures arising during the ownership of

an asset”.

Many universities and governmental departments have adopted LCCA and developed their

own LCCA procedures such as Mearig et al. (1999) and Davis M. et al. (2005). In 1999,

Mearig and Coffee proposed the LCCA handbook for State of Alaska Department of

Education & Early Development. LCCA is suggested to building owners for broadening their

perspective to include not just the facility in terms of costs to design and to build, but also

operations, maintenance, repair, replacement and disposal costs. The guidelines were

established in the handbook to assist Alsakan school districts, their consultants, and

communities in evaluating the LCC of school construction decisions.

Later on in 2006, Davis M. et al. developed a LCCA guideline at University Stanford Land

and Buildings. The study categories provided case studies of LCCA implementation in energy

systems, mechanical systems, electrical systems, building envelope and structural systems.

LCCA was defined as a process of evaluation the economic performance of a building over its

entire life and base on the assumptions that more than one alternative option can meet the

programmatic needs and achieve acceptable performance while theses options have differing



initial costs, operating costs, maintenance costs and possibly different life cycles. A detailed

LCC spread sheet was provided to explain the calculation.

International Standard Organization (ISO) document 15686-5 (2008) provided the standard of

LCC. It was subjected to Building & constructed assets – Service life planning - Part 5: Life

cycle costing. The document covered LCCA Scope, normative references, decision variables,

environmental impacts, period of analysis, uncertainties and risks and reporting. Terms,

definitions and abbreviations of LCCA were listed to provide common communications

between projects.

Regarding impact assessment using LCCA to evaluate alternatives which have potential to

meet MARPOL Annex VI regulation limits, there are three studies worthy noting, namely one

thesis work from Norwegian School of Economics and Business Administration (Alvestad T.

R., 2011), a Green Ship of the Future project (Klimt-Mollenbach C. et al., 2012) and a

scrubber selection guide from The Glosten Associates (Reynolds K. J. et al., 2012).

Alvestad T. R. (2011) analysed three Norwegian Utkilen ships’ LCC for three different

alternatives regarding MARPOL Annex VI emission regulations. A 25 year lifetime was

assumed in the study to compare ships using IFO380, MGO, scrubber technology and LNG

and NPV cost comparisons were made. Scrubber cost estimation was made and generalised

based on previous studies in terms of cost per kilowatt and no specific scrubber type was

mentioned to represent the scrubber installed on the ships. It is stated that lacking experience

and application of SOx scrubbing technology and low availability of LNG limits the adoption

of the alternatives. Furthermore, the author mentioned an expanding market for LNG is to be

expected, while SOx scrubbing technology is also most likely to have further development.

Klimt-Mollenbach C. et al. (2012) conducted an analysis based on an existing 38500 DWT

tanker vessel, evaluated two potential solutions able to meet the requirements of the IMO

regulations regarding SOx in the Emission Control Areas in 2015 and globally in 2020.

Scrubber installation and LNG propulsion are proposed as solutions regarding technical and

economical feasibility, while MGO is used as the base case. It concluded that the payback

period of the scrubber is primarily sensitive to the price spread between HFO and MGO, and

it depends also highly on the operation time inside ECAs. For the case tanker, the study

12 Shih-Tung Shu


indicated that the most favourable from an economical point of view will be to switch to

MGO when operating in ECAs.

Reynolds K. J. et al. (2012) developed a guideline for the scrubber selection in determining

the emission requirements and calculated potential cost saving and provided information

about the integration and operational challenges of varies EGTs technologies. The study

emphasized mainly on the SOx scrubber technologies. The life cycle cost analysis was

performed with respect to a 4000 TEU container, a 2000 TEU container and a 60000 DWT

tanker with three different routes. Comparisons between different SOx scrubbers on the same

vessel were also made. The study summarized the integration, operations and maintenance

practicalities and indicated that starting in 2015 ships which burn at least 4000 metric tons of

fuel oil annually within an ECA should consider the EGTs. It claimed that in spite of the

challenges of ship arrangement, operations and logistics, the cost savings potential remains

significantly high.

1.3.3. Installation of Abatement Technologies Related

When installing an EGT system onboard, impacts of installation are typically the major

concerns of ship owners regarding technical and economical aspects, while local authorities

and concern more about environmental influences. There are some studies available based on

the actual installations of abatement technologies onboard which might provide more details

and experiences collected.

Hufnagl M. et al. (2005) conducted a final report regarding effects of seawater scrubber

onboard P&O ferry Pride of Kent. Sampling tests were the main focus. Nutrients, pH value,

temperature, trace metals, polycyclic aromatic hydrocarbons (PAH) and plankton were

measured and the accumulation and two toxicity tests were also performed. It stated that

higher sulphate and nitrate concentrations were found in the outlet, but no decrease of the pH

inside the ports or close to the ferry was observed. The study indicated that there was no

negative influence of the scrubbing system to the port environments.

Bradley M. J. (2006) submitted a final report to the port authority of New York and New

Jersey and New York City Department of Transportation. The study reported the analysis,

specification, installation, regulatory approvals and emission performance assessment of SCR



system on the Alice Austen, a ferry ship between Staten Island and Manhattan. It was stated

that from early 2003 to 2006 around 16.5 tons of NOx reduction per year were removed. The

analysis showed that SCR system was capable to provide approximately 52% to 66%

reduction for a one-way trip with less than 8 ppm of ammonia slip.

Robbins M. J. (2007) submitted a feedback report of SCR Project onboard MV Solano which

was procured and delivered to the City of Vallejo as a low-emissions ferry in August 2004. It

mentioned that The SCR system added $472,594 to the cost of the $11,300,000 vessel, or

4.2% of the total cost of construction and the operating cost impact were judged to be $723

per day including urea consumption and catalyst block replacement. A SCR failure situation

was reported and the possible explanations were salt damage, thermal damage, and possibly

vibration or physical shock damage to all of the catalyst blocks.

Holland America Line and Hamworthy Krystallon submitted (2010) a final report of Seawater

Scrubber Technology Demonstration Project on the MS Zaandam to the U.S Environmental

Protection Agency. The report presented the project overview, environmental monitoring,

engine emission monitoring, washwater monitoring and evaluation of soot in the wash water

discharge. It stated that the testing platform proved the reduction efficiency of the open loop

seawater scrubber system with 75% reduction rate for SOx and 57% reduction rate for PM.

Furthermore, the periodic washwater analyses were conducted to monitor pH value,

temperature, turbidity, alkalinity, chemical oxygen demand and conductivity. The report

concluded that additional system components must be installed to remove the soot from the

wash water discharge and some future tasks like ambient water quality testing, refurbishing

scrubber internals and fitting the demister were anticipated.

Kjølholt J. et al (2012) contributed to an environmental project organized by Danish

Environmental Protection Agency. The study provided to a detained assessment regarding the

water discharge from exhaust gas scrubbers. It was found that compared to current

environmental acceptability levels the releases from scrubbers can be expected to be

considerably below the levels of ecological concern. Nevertheless, risk assessments must be

taken for any specific area regarding contamination levels and releases from other sources.

The sludge sample taken from a seawater scrubber installed onboard Ficaria Seaways

operating in closed loop freshwater mode showed the concentration of nickel, vanadium and

petroleum hydrocarbons which should be classified as hazardous waste and must be treated

14 Shih-Tung Shu


and disposed of accordingly when transported to land. The costs of sludge disposal in Danish

ports were estimated in the scenario that it must be transported to the waste treatment

facilities.

Hansen J.P. (2012) wrote the public testing report of a hybrid scrubber system installed on-

board the DFDS vessel Ficaria Seaways. It was an installation project co-operated between

Alfa Laval, MAN Diesel & Turbo. The project was co-financed by the Danish Environmental

Agency under a program for testing and promoting new environmental technologies. The test

results showed a washwater discharge rate of 2 - 4 m3/hr for the closed loop mode operation

while up to 1000 m3/hr of water is discharged in SW mode. The soot collected in closed loop

mode consists of unburned hydrocarbons and heavy metals and the amount of soot in the open

loop mode was so limited that the turbidity measurement and PAH content are below the

limits stated in MEPC guidelines.

1.3.4. Other Literature Reviews

Besides the major literatures focusing on the EGT system, two more studies are presented

here regarding the emission factor and the end-of-life issue. It was noted (Cooper D., 2002)

that emissions from ship can be quantified. The study presents emissions factors which were

derived from a database consisting of exhaust measurements from around 80 ships involving

ca. 170 marine engines. A review of emission data and published literature emission factor

databases has been conducted. In addition, different future scenarios for the year 2005 and

2008 were calculated.

The ship recycling issues were introduced (Lloyd’s Register, 2011) regarding practice and

regulation today. A brief ship scrapping history was first summarized to provide conventional

ship recycling locations, methodologies and conditions. The Hong Kong Convention

contributing to the safe and environmentally sound recycling of ships was presented with the

entry into force conditions. Once it enters into force, ship recycling must comply the

regulations and prepare documentations such as Inventory of Hazardous Material and Ship

Recycling Plan. Recycling case studies were presented for better understanding the

difficulties and challenges.



2. LIFE CYCLE COSTING

Without truly understanding the concept term: “life cycle costing”, no life cycle cost analysis

can be properly performed. As defined by White et al (1976): “The life cycle cost of an item

is the sum of all funds expended in support of the item from its conception and fabrication

through its operation to the end of its useful life”. In other words, a product’s life cycle

costing equals to all the expenses that one has to pay for the product before either abandoning

it or putting it on the shelf forever.

Life cycle cost typically can be divided into four categories: construction, operation,

maintenance and end-of-life, or so called purchasing, using, maintenance and disposal as

shown in the figure below: (ISO, 2008)

Life-cycle cost

Construction Operation Maintenance End-of-life

Figure 3. Categories of LCC

While life cycle cost is a comprehensive concept, a life-cycle cost analysis (LCCA) is more of

a tool that measures when the expenses come in and how much they actually cost now or in

the future. To precisely describe LCCA, it is an economic method of evaluating a project’s

cost throughout its life-cycle systematically. Alternatives fulfilling the project requirements

should be provided for life-cycle cost analysis in order to compare the overall economic

performance throughout the stage of construction, operation, maintenance and end-of-life.

Why do people need LCCA and when and where do they use LCCA? To answer these

questions, the theory and some applications of LCCA must be introduced in the following

section.

16 Shih-Tung Shu


2.1. Theory and Applications

LCCA has been a powerful method for engineering projects and became popular in 1960s that

U.S. government agencies took the concept as an instrument to ensure the cost effectiveness

of purchasing any equipment. (Bescherer F., 2005)

It was then very popular among governmental projects and has been passed down to private

enterprises later on for building constructions, production line equipments and so on. LCCA

is especially suitable for early project stage that needs cost-effectiveness evaluations not only

from single first cost or add on operation costs but from long-term cost perspectives which

give a better assessment for decision making.

LCCA can be implemented at any level of design procedure as well as any existing

engineering system to evaluate the cost throughout the product life time. For examples:

Building construction, automobiles, airplanes, ships building or as the study focuses, the

marine scrubber technologies will be the target of LCCA.

To perform LCCA, a terminology is needed for user to follow or to make sure the definitions

of life cycle costing is the same no matter where and when it is mentioned. In this case, ISO

15686 gives guidelines for performing LCCA which takes relevant costs arising from

acquisition through operation to disposal. It includes a comparison between alternatives or an

estimation of future upcoming costs within the designated study period.*”Alaska handbook”

Cost, Time and Discount rate are three key components of LCCA. Cost represents all the

expenses incurred throughout the life-cycle. Time marks the study period of which incurred

costs should be taken into account. And discount rate transforms the future costs into present

day values. These three components build up principles and purposes that are discussed in the

next section.



2.2. Principles and Purposes

2.2.1. Cost

There are two categories of cost or so called expense, namely initial expense and future

expense. Initial expenses are all costs incurred prior to occupation of the facility, while future

expenses are all costs incurred after occupation of the facility. Cash flow of cost is discounted

by the real or nominal discount rate to transform the future expenses into discounted costs and

can be summed up as the net present cost.

2.2.2. Time

The second LCCA component is Time, or so called study period. The study period is the

period of time over the ownership of the equipment that all costs incurred are taken into

account of the evaluation. The study period can vary from ten to fifty years depending on the

preference of the user. Normally, the study period is shorter than the intended life of the

equipment.

2.2.3. Discount Rate

The third LCCA component is Discount rate. ISO 15696-5 defines discount rate as factor or

rate reflecting the time value of money that is used to convert cash flows occurring at

different times to a common time. There are two types of discount rate, namely nominal

discount rate and real discount rate. Nominal Discount Rate takes general inflation or

deflation rate into account in the cost of a particular asset under consideration while Real

Discount Rate doesn’t.

In order to combine the expenses in the future and in the present time, the present value of the

all expenses has to be determined first based on the same time frame, because cost accruing in

the future has to be discounted account for the fact that it has less value than in the present

day. The NIST Handbook 135, 1995 edition, defines Present Value as “the time equivalent

value of past, present or future cash flows as of the beginning of the base year.” The term of

18 Shih-Tung Shu


Net Present Value (NPV) represents the summation of the discounted future cash flows and

sometimes it can be defined as Net Present Cost (NPC) if only costs are included.

2.2.4. LCCA Procedure

There are many approaches to perform a LCCA and there is no standard procedure recognized

for users around the world. As long as the definition and objective of LCCA are clear enough

and the three key components are handled properly, the approach can be a good LCCA

procedure.

In the Guidelines for LCCA of Stanford University (Davis M. et al., 2005), the LCCA

procedure is divided into five steps as shown in Figure 4.

Step 1. Establish clear objectives

Step 2. Determine the criteria for evaluating alternatives

Step 3. Identify the base case and develop alternative designs

Step 4. Gather cost information

Step 5. Perform LCC calculations for each alternative

Figure 4. Steps of LCCA

Step 1: Establish clear objectives. Without clear objectives, LCCA cannot be a successful tool

to evaluate the cost-effectiveness of the project. Before moving on to any calculation,

providing a project description and goal of performing LCCA can establish a better

understanding of the project so as to ensure that the decision making process is on the right

track.

Step 2: Determine the criteria for evaluating alternatives. The two typical criteria considered

in LCCA are the life-cycle cost and the payback time over a designated study period between



all alternatives. In other words, decisions can be made depending on the results of total costs

and the time needed for recovering the initial investment.

Step 3: Identify the base case and develop alternative designs. The alternative that fulfills the

standard design or minimum requirements for a project is defined as the base case. There

should be other alternatives to be evaluated against the base case in LCCA. Information for

options has to be provided in details comparing the base case to run the proper life-cycle cost

calculations.

Step 4: Gather cost information. Cost information can be obtained from a variety of sources,

including cost estimating consultants, contractors, vendors, designers and users. From cradle

to grave, all costs should be gathered, for example, construction, utility, maintenance, service

and in some cases remodeling costs.

Step 5: Perform LCC calculations for each alternative. LCC calculations for each alternative

are performed for the last stage. Besides LCC the criteria defined in step 2, sensitive analysis

can be conducted as well to include possible future scenarios. Interpretations of final result

based on the sensitive analysis can be different.

By implementing this five steps procedure to the topic of this study, a brief project description

containing the objectives, cost metric, alternative group and cost information is introduced in

the following section.

20 Shih-Tung Shu


2.3. Scrubber System Project Description

A brief project description of scrubber system can be presented by following the five steps

procedure and it includes a clear objective, determination of alternatives, baseline and cost

information:

This study uses the terminology of LCCA to understand the economical impacts between

different scrubber systems. It aims at the exhaust abatement technologies in accordance with

MARPOL Annex VI regulation 14 which limits on the sulphur content of fuel to restrict SOx

and particulate matter emissions. Scrubber is designed to clean the exhaust gas.

The objective of the study is to evaluate a number of scrubber types for retrofitting or new-

built ships and determine which, if any, are worth implementing. The life-cycle cost of every

scrubber system alternative will be calculated and compared.

There are mainly four scrubber types, namely open loop seawater, closed loop fresh water,

hybrid and dry scrubbers. The base case is using marine gas oil without installing any of the

scrubber system.

Cost information of the scrubber is collected from research studies, vendor’s brochures, news

articles and inquires to the vendors. No accurate price can be provided due to lack of

commercial installations. The LCCA will be introduced and performed in Chapter 6.



3. EXHAUST GAS TREATMENT TECHNOLOGIES OVERVIEW

The increasing demand from society for air emission reduction has accelerated the

development of the Exhaust Gas Treatment (EGT) systems. Onshore EGT systems for

vehicles and power plants have been developed and used in a wide range of applications over

the past two decades, while the number of marine EGT applications remains relatively few.

The maturity of EGT technology itself has long proven. Nevertheless, for marine uses it

requires more application studies and users’ feedbacks.

Based on the abatement target, EGT systems can be divided into three categories: Sulphur

Oxide (SOx), Nitrogen Oxide (NOx) and Particulate Matter (PM) abatement technologies.

Although some products claim to be able to remove more than one pollutant together, it is still

discussed separately since there is insufficient information and empirical data on the

combined technology available for further discussions.

3.1. Sulfur Oxide (SOx) Abatement Technologies

3.1.1. Wet Scrubbers

Water is utilized to wash off the sulphur content of exhaust gas in the use of wet scrubbers.

Depending on the type of scrubber, either seawater with natural alkalinity or fresh water

dosed with sodium hydroxide (NaOH) is brought into close contacts with the exhaust gas and

treated properly before discharging back to the ocean or circulating back to the system. Wet

scrubbers are usually installed in the engine casing or funnel in a vertical direction, since it is

not possible to install the scrubbers horizontally as the efficient needs the counter current

interaction between the exhaust gas and the scrubbing water.

Wet scrubbing technology is a proven technology which has been utilized on many land-

based industrial applications for years. Many experts and vendors believe that wet scrubbing

is a simple and efficient way to remove SOx and particulate matter from marine engine

exhausts.

Wet scrubbers can be divided into three types: Open Loop Sea Water Scrubber (SWS) system,

Closed Loop Freshwater Scrubber (FWS) system and Hybrid Scrubber (HS) system which

22 Shih-Tung Shu


can operate in both open and closed loop modes. Some major components are used in all wet

scrubbers, such as a scrubber unit, water treatment plant, residual handling facility for sludge

and sets of scrubber control and emission monitoring system. Pipelines, pumps, coolers and

tanks will link through all the major components in different way depending on scrubber

types and engineering design.

Open Loop Seawater Scrubber (SWS) System

In a SWS system, seawater is pumped from the sea into the scrubber unit, mixed with exhaust

gas, filtered and cleaned in the water treatment system before discharged back into the open

sea, as shown in the schematic drawing in Figure 5. Sludge filtered from the washwater is

stored in the sludge tank which needs to be disposed of at port facilities and can not be

incinerated onboard. No washwater is re-circulated in the SWS system.

The basic chemistry for open loop seawater system can be described along the following

principles:

SO2 + H2 → H2SO3 (sulphurous acid) → H+ +HSO3

- (bisulphite)

HSO3- (bisulphite) → H

+ + SO3

2- (sulphite)

SO32-

(sulphite) + 1/2 O2 → SO42-

(sulphate)

Sulphur dioxide (SO2) will be dissolved and ionised in seawater creating sulphurous acid. The

sulphurous acid is then ionised in water with normal acidity creating bisulphite and sulphite

ions. Sulphite ions will then be oxidised into sulphate since oxygen is in the seawater.

SO3 + H2O → H2SO4 (sulphuric acid)

H2SO4 + H2O → HSO4- (hydrogen sulphate) + H3O

+

HSO4- (hydrogen sulphate) + H2O → SO4

2- (sulphate) + H3O

+

Similarly for the sulphuric acid formed from SO3, it will undergo reactions which turn

hydrogen sulphate into sulphate ions. The acidity resulting from the chemical reactions in

SWS systems is neutralised by the alkalinity in the seawater by pumping sufficient seawater

into the scrubber unit. Therefore, the amount of seawater needed depends significantly on the

natural buffering capacity of seawater.



Figure 5. A open loop SWS system [Lloyd’s Register 2012]

Closed Loop Freshwater Scrubber (FWS) System

In a FWS system, fresh water is pumped from freshwater tank into the scrubber unit, mixed

with exhaust gas, filtered and cleaned in the water treatment system before circulating back to

the system. Unlike the SWS system, washwater is reused in the system. Sludge filtered from

the washwater is stored in the sludge tank, which also needs to be disposed of at port facilities

and can not be incinerated onboard. The schematic drawing can be shown in Figure 6.

Sodium Hydroxide (NaOH) is dosed to the washwater to buffer the acidity resulting from the

chemical reactions instead of the alkalinity in the seawater. The basic chemistry for open loop

seawater system can be described along the following principles:

2 Na+ + 2 OH

- + SO2 → Na2SO3 (aq sodium sulphite) + H2O

2 Na+ + 2 OH- + SO2 + 1/2 O2 → Na2SO4 (aq sodium sulphate) + H2O

SO3 + H2O → H2SO4 (sulphuric acid)

2 NaOH + H2SO4 → Na2SO4 (aq sodium sulphate) + 2H2O

24 Shih-Tung Shu


Figure 6. A closed loop FWS system [Lloys’s Register 2012]

Sulphur oxides are dissolved and react to form sodium bisulphite, sulphite and sulphate. The

proportion of each relies on the pH value and available oxygen.

Small quantity of treated washwater is bled off to reduce the concentration of sodium sulphate;

otherwise the formation of sodium sulphate crystals will lead to progressive degradation of

the washwater system. The typical bleed-off rate is approximately 0.1m3/MWh. The bleed-off

of treated washwater can either be kept in the holding tank for port facility or discharged into

the sea.

Hybrid Scrubber (HS) System

A HS system can be operated in either open or closed loop mode. It provides the flexibility

for ships to operate when travelling inside low alkalinity region or sensitive region where

washwater discharge is forbidden. On the other hand, a HS system is more complex than

either SWS or FWS system. More components need to be installed onboard. The schematic

drawings of open loop mode and closed loop mode of the HS system are shown as in Figure 7

and Figure 8 respectively.



Figure 7. A HS system operating in open loop mode [Lloys’s Register 2012]

Figure 8. A HS system operating in closed loop mode [Lloys’s Register 2012]

3.1.2. Dry Scrubbers

Unlike wet scrubber, using either sea water or fresh water as medium, dry scrubber utilises

calcium hydroxide in granulate form to clean out the sulphur contents. As shown in Figure 9,

26 Shih-Tung Shu


granulates drop slowly from a supply silo through a two-stage construction of absorber to a

discharge system under gravity.

When exhaust gas passes perpendicularly through an absorber full of calcium hydroxide

granulates, the first stage of granulates, located below the second one, is used as a sacrificial

layer for removing the rough sooty particles and other residuals, in a similar way of

particulate matter filter. The second stage of granulates, meeting the exhaust gas while still

fresh, is where the desulphurization occurring and the chemical reactions scrub away the SO2

and SO3. The dwell time of the exhaust gas inside the absorber is approximately 3.7 seconds.

The used granulates, which are turned into gypsum with the retained spherical form, are then

conveyed by the discharge system to a granulate storage onboard. The schematic drawings of

dry scrubber system (Available from: http://couple-systems.de/index.php/dryegcs-new.html

[Accessed 6 January 2013]) is shown as in Figure 9.

Figure 9. A dry scrubber system [Couple System]

A monitoring system is needed to ensure the automated process of continuous supplying and

discharging. The basic chemistry for dry scrubber can be described along the following

principles:



SO2 + Ca(OH)2 → CaSO3 (calcium sulphite) + H2O

2CaSO3 + O2 → 2CaSO4 (calcium sulphate)

CaSO4 + 2H2O → CaSO4.2H2O (calcium sulphate dehydrate – gypsum)

Calcium sulphite is first form due to the reaction between sulphur dioxide (SO2) and calcium

sulphite (CaSO3), and then oxidised and hydrated in the stream to form gypsum. Similarly for

SO3, it will undergo reactions and generate gypsum at the end.

SO3 + Ca(OH)2 + H2O →CaSO4.2H2O (calcium sulphate dehydrate – gypsum)

A dry scrubber system offers compatibility with other EGT systems, since the process simply

brings the exhaust gas in contact with granulates and the chemical reaction is exothermic, no

heat is taken away. In other words, the dry scrubber can be placed before a waste heat

recovery or a Selective Catalyst Reaction system which has an effective catalytic reduction

temperature ranging from 300°C to 500°C.

The onboard monitoring system of dry scrubber can take up to 5 exhaust gas samplings at the

same time. Typical locations are raw exhaust gas upfront of the scrubber, cleaned exhaust gas

downstream of the scrubber and the intermediate of stage 1 and 2 inside the scrubber.

Calibration and maintenance needed are few according to the onboard monitoring manual

from the scrubber manufacturer. Only in case of the sensor failure, the sensor must be

replaced, otherwise there is no specific maintenance needed for sensors and transmitters.

(Couple system, personal communication)

The operation onboard can be controlled by the monitoring display, such as conveyers,

rotating value sluice, etceteras. The performance data of the past 18 months are recorded to a

hard-disk inside the system and a copied data file can be obtained by surveyors with the USB

stick installed inside the control cabinet. Data are also sent to the manufacturer on a weekly

basis.

28 Shih-Tung Shu


3.2. Nitrogen Oxide (NOx) Abatement Technologies

The formation of NOx is highly relevant to the combustion process. There are three primary

sources of NOx, namely thermal NOx, fuel NOx and prompt NOx. Thermal NOx, often

regarded as the most relevant source when using natural fuel, is temperature dependent. In

other words, unlike SOx emission is directly related to the fuel used as input, the combustion

process inside the engine is more important for NOx emission generation. Therefore, NOx

emission depends significantly on the engine type. Normally slow engines produce more NOx

than higher speed engine. NOx emission factors were investigated (Cooper D., 2002) and can

be predicted as emission rate with respect to kilogram per hour.

NOx reduction methods can be divided into primary and secondary solutions. For primary

methods, abatement technologies are applied directly to the source of NOx and lower the

formation of NOx emissions; while secondary methods reduce NOx emissions only after they

have already been generated, the so called after treatment.

There is a wide range of methods to reduce NOx emissions by modifying engines. All the

primary methods tend to improve and optimise combustion process, improve air charge

characteristics or change the fuel injection system. Researches have been made over decades

to determine the correct combination of modifications appropriate for each engine type.

3.2.1. Primary NOx control

In Engine and Operational

By changing conventional fuel valves with sliding low-NOx fuel valves, the spray distribution

in the combustion chamber can be optimised without compromising on temperature and

thereby engine reliability. Heat release with sliding valves is lower than conventional valves

and results in a beneficial NOx reduction. (Ritchie A. et al., 2005)

The fuel consumption is not affected after sliding valve installation. The expected life span is

around 5 years. Once installed the life time of the valves will be the same as for conventional

valves.



Besides the basic “In Engine Modification” (IEM), Engine manufacturers have developed and

combined IEM to their products to reduce NOx emissions, since any engine modification

today needs to fulfil tier II limit. Combinations of advanced IEM from engine vendors are

listed in Table 2 with NOx efficiency.

Table 2. Advanced IEM combinations [Ritchie A. et al., 2005]

Direct Water Injection (DWI)

By injecting water to cool down the combustion chamber before combustion process begins,

this enables cooler combustion space and the NOx formation can be thus reduced. During the

water injection, the atomized water droplets will be vaporized immediately in the combustion

chamber and the peak temperature is lowered as a combined effect of vaporization of liquid

water absorbing heat and increased specific heat of the gas around the flame. Too much water

added will result in too long injection duration, which increases soot formation. After DWI

modification, storage and bunkering of freshwater is needed for operation. (Ritchie A. et al.,

2005)

Fuel consumption is the same and there are no noise effects. It is recommended that the fuel

used for DWI system should have sulphur content lower than 3%. Regarding emissions, it is

reported that it can meet MARPOL tier II limit based on the application of MS Silja

Symphony, which retrofitted DWI system since 1999.

30 Shih-Tung Shu


Humid Air Motor (HAM)

Humid Air Motor (HAM) system is a technology that uses heated charge air with water

vapour to reduce NOx formation during the combustion process. Seawater is used for cooling

and is heated by waste heat from the engine. HAM technology is able to reduce NOx

emissions up to 80 %. In order to achieve the high NOx removal rate, three times as much

water vapour as fuel must be introduced into the combustion chamber.

Exhaust Gas Recirculation (EGR)

Exhaust gas recirculation (EGR) technology uses a fraction of the exhaust gas which is

filtered, cleaned, cooled and re-circulated back to the engine charge air. Less thermal NOx

formation can thus be done due to the reduced combustion temperature, since the specific heat

capacities of the principal exhaust components are higher than air. Furthermore, exhaust gas

re-circulated means less oxygen and the formation of nitrogen oxidation is also reduced.

A proportion of the exhaust gas from before the engine turbocharger is first cleaned by a high

pressure exhaust gas scrubber to remove sulphur and PM contents, which will cause corrosion

and fouling to the engine. A cooler will lower the temperature of the re-circulated exhaust gas

and a water mist catcher will remove entrained water droplets. Before re-entering back to the

engine, a high pressure blower will increase the pressure of the re-circulated exhaust gas. All

the process is controlled by an automated system. The schematic drawings of EGR system is

shown as in Figure 10.

The scrubber unit used in EGR system is more compact than a normal scrubber, since the

exhaust density is higher. In a test EGR system coordinated by MAN Diesel & Turbo (2012),

a closed loop wet scrubber system is fitted with sodium hydroxide dosing unit, water

treatment systems and so on. It has be noted that even though up to 80% of sulphur content

can be removed by EGR scrubber, an additional scrubber system is still required to clean the

exhaust gas again in order to fulfil MARPOL tier III NOx emission limit.

EGR system has proven to be a reliable technique for NOx emission reduction and it is not

new for automotive industry. For marine EGR system, there are still many challenges to be

solved, but it is regarded as one of the possible technologies to reduce ship’s emission.



Figure 10. An EGR system [MAN Diesel & Turbo]

EGR technology is part of the HERCULES (Higher-Efficiency Engine with Ultra-Low

Emissions for Ships) project supported by the European Commission. Starting from

HERCULES-A in 2007, a complete EGR system for two-stroke engines was first developed

including a FWS scrubber. A potential for NOx emission reductions up to 70% was

confirmed as stated in the press. (Available from: http://www.ip-hercules.com) [Accessed 6

January 2013]

In 2008 HERCULES-B project followed up, and ended in 2011 with the final results. Above

85% NOx reduction was achieved, higher than the initial target 80% reduction, with

acceptable SFOC, CO and soot. By using 3% sulphur HFO, more than 600 EGR running

hours without negative impact on combustion chamber is achieved. It is stated that two-stroke

diesel engines with EGR system comply with MARPOL tier III NOx regulation. Moreover,

EGR service test has shown that EGR is a future NOx reducing technology for HFO operation.

(Available from: http://www.hercules-b.com) [Accessed 6 January 2013]

In 2012 HERCULES-C project initiated. One of the goals is to integrate various emission

control technologies developed in the previous research projects to achieve near-zero

emissions. (Available from: http://www.hercules-c.com) [Accessed 6 January 2013]

32 Shih-Tung Shu


3.2.2. Secondary NOx Control

Selective Catalytic Reaction (SCR)

Selective Catalyst Reaction (SCR) system utilizes the chemical reaction involving the

reducing agent, ammonia (NH3), nitrogen oxide (NOx) is transformed into elemental oxygen

(O2) and nitrogen (N2), which are no longer harmful to human body. The chemical reaction

takes place when the exhaust gas, mixed with the ammonia spread, enters into the catalyst

block, which is composed of vanadium pentoxide (V2O5) with the support from a structure

frame made of titanium dioxide (TiO2) and tungsten oxide (WO). The schematic drawings of

SCR system is shown as in Figure 11.

Figure 11. A SCR system [Jürgens R, 2011]

Liquid urea is used onboard instead of ammonia considering its characteristics of non-

hazardous, colourless and odourless. It would be injected and atomize by the compressed air

into the exhaust gas flow. Urea is then decomposed into ammonia to proceed the reduction

reaction inside the catalyst block. The basic chemistry for SCR system can be described along

the following principles:

(NH2)2CO (urea) → NH3 (ammonia) + HNCO (isocyanic acid)

HNCO + H2O → NH3 + CO2

First the urea is decomposed into ammonia and isocyanic acid before the catalytic block. At

the catalytic block, the main SCR reaction takes place as nitric oxide dominates in the exhaust,

as shown below.



4NO + 4NH3 + O2 → 4N2 + 6H2O

When the fastest rate is up to 1 to 1 of NO2: NO ratio, the reaction occurs as described in the

reaction below.

2NO + 2NO2 + 4NH3 → 4N2 + 6H2O

At higher ratios the excess NO2 reacts slowly:

6NO2 + 8NH3 → 7N2 +12H2O

SCR system is a proven and efficient technology for NOx emission reduction. It has been

used for land-based applications for years. For the last 20 years major engine OEMs and SCR

system vendors have gained considerable experience in the marine SCR systems. Many 4-

stroke engines have had SCR systems installed. SCR system is improved continuously with

optimised components. Experience of SCR in two-stroke low speed engines is also growing.

To date, over 500 marine SCR systems have been installed onboard.

It is believed that SCR system is the only mean of compliance available to meet MARPOL

tier III NOx limit with more that 90% of emission reduction; while EGR system is still on the

early stage of development and it needs time to be commercialized.

34 Shih-Tung Shu


3.3. Particulate Matter (PM) Abatement Technologies

U.S EPA defines Particulate matter (also known as particle pollution) as a complex mixture of

extremely small particles and liquid droplet. It consists of a number of components such as

acids (nitrates and sulphates), organic chemicals, metals and soil or dust particle. The size of

particle is crucial and linked directly to their potential for causing health problems. Inhalable

particles can cause different levels of damage to human beings depending on their penetration

efficiency. The relationship between penetration efficiency and particle aerodynamic diameter

in micrometer is shown as Figure 12. (Aavailable from: http://www.epa.gov/apti/Materials/

APTI%20435%20student/Student%20Manual/Chapter_4_noTOC-cover_MRpf.pdf)

[Accessed 6 January 2013]

Figure 12. PM penetration efficiency.

PM2.5 and PM10 are terms used by U.S. EPA to describe particle up to 2.5 micrometer and up

to 10 micrometer. Particle with 10 micrometer in diameter or smaller is the main concern of

U.S. EPA since it can penetrate through nose and lung and cause server health problems by

affecting heart and lungs.

Regulation 14 of MARPOL Annex VI regulates PM through the sulphur content of the fuel

oils to be used, while U.S. EPA provides the PM standards for Category 1 and 2 marine diesel

engines in terms of gram per kilowatt.



There are still debates about how PM should be regulated since it is difficult to conduct PM

measurement and some studies show that most particles removed are larger particles, while

the harmful gaseous particles remain in the exhausts.

3.3.1. Diesel Particulate Filter (DPF)

Diesel Particulate Filter (DPF) is a common technology that traps down particulate matter

physically from a diesel engine by forcing exhaust stream passing through a filter. The filter

can be made of cordierite, silicon carbide, ceramic fibre or metal fibre.

After the PM is trapped, regeneration can take place either passively or actively to remove or

burn the accumulated soot from the filter. Passive regeneration uses the heat directly from the

exhaust gas stream when the temperature is high enough to initiate PM combustion process,

while active regeneration needs added fuel, heat or driver action to initiate the process.

For passive DPF, regeneration depends only on engine exhaust heat and thereby the duty

cycle of the engine is crucial for operation. It has the advantages of lower capital cost and

simple installation, but the regeneration process is uncontrolled and it may not be suitable for

every engine due to the duty cycle.

On the other hand, using active DPF can be advantageous, in which regeneration occurs

automatically and its frequency can be controlled by a system. Meanwhile, high capital cost,

extra power source for heating required, complex installation and down time for regeneration

are the downsides.

Besides regeneration, filters need to be cleaned or replaced periodically to avoid non-

combustible materials and ashes. Excessive PM and ash accumulation can cause high back

pressure. Therefore, proper maintenance and cleaning are important to DPF systems.

DPF technology is a common and useful tool of emission after treatment for automotive and

locomotive industries, while most of marine DPF systems are installed only for smaller

vessels using ultra-low sulphur fuel, such as tugs, yachts or ferries.

36 Shih-Tung Shu


3.3.2. Diesel Oxidation Catalyst (DOC)

Instead of trapping PM down physically, Diesel Oxidation Catalyst (DOC) technology uses

chemical reaction to oxidize carbon monoxide, gas phase hydrocarbons, and the soluble

organic fraction of diesel PM.

It consists of a monolith honeycomb structure coated with platinum group metal catalyst, and

packaged in a stainless steel container. The honeycomb structure with many small parallel

channels provides a high catalytic contact area to exhaust stream. When the exhaust gas gets

in contact with the catalyst, several exhaust pollutants are converted into carbon dioxide and

water, since diesel exhaust gas already contains sufficient amounts of oxygen for the reactions.

The basic chemistry for DOC system can be described along the following principles:

C (soot) + O2 → CO2

CO + 1/2O2 → CO2

Cx Hy + O2 → CO2 + H2O

Temperature is an important factor for DOC system. It requires a minimum exhaust

temperature of around 200°C for oxidation to take place, and the catalyst activities also

increase with higher temperature. However, at high temperatures, for instant above 400°C, a

counterproductive process may occur in the catalyst, which will increase diesel particulate

matter. The chemical reaction of this counterproductive process is shown as below:

SO2 + 1/2O2 → SO3

SO3 + H2O → H2SO4

In order to avoid the undesirable formation of the extra SO4 particulates, using low sulphur

fuel is necessary. The compatibility with other SOx abatement technologies is possible with

careful temperature arrangement; otherwise a re-heater might be needed.

3.3.3. Electrostatic Precipitator (ESP)

Electrostatic Precipitator (ESP) is an after treatment technology that uses induced electrostatic

force to remove particulate matter from the exhaust stream. A high voltage is applied to



generate electrical field between electrode and collecting board. When the exhaust gas stream

flows through the field, particulate matters are fist charged by ions supplied around the

electrode board, pushed toward the collecting board by the Coulomb force and captured by

the board. The schematic drawing of ESP technology is shown as Figure 13. (Available from:

http://www.hitachi-pt.com/products/energy/dustcollection/principle/dustcollection.html)

[Accessed 6 January 2013]

Figure 13. An ESP system.

ESP system was reported to be highly efficient of removing particulate matters from diesel

engines without increasing back pressure. It can be operated in low power since the electrical

power needed is to push the aerosol particles instead of the whole cleaning medium such as

the washwater in scrubber systems.

Particles collected on the board need to be cleaned periodically. Rapping collecting plate,

scraping off with a brush or using water film or spray can be implemented to clean the ESP

collecting plate.

The PM collection efficiency of ESP is affected by several design factors such as the area of

specific collection plate, aspect ratio, spacing between plates and the size of PM. The

theoretical moving velocity is almost proportional to the size of particle in diameter, which

means it takes longer for smaller particles to be collected than larger ones. In this case, a

bigger ESP in size is needed to prolong the treating time to have the same collection

efficiency for all particles.

38 Shih-Tung Shu


3.4. Summary

The pollutant removal efficiency regarding SOx, NOx and PM for different technologies can

be summarized from various data sources in Table 3.

Table 3. SOx, NOx and PM abatement technologies

SOx abatement technologies1 SOx NOx PM Large Engines? Regulation?

Scrubber system >95% 70-90% V SOx ECA

NOx abatement technologies2 SOx NOx PM Large Engines? Regulation?

Internal engine modification (IEM) 30% V NOx Tier II Direct water injection (DWI) 50% V NOx Tier II Humid air motor (HAM) 70% V NOx Tier II Exhaust gas recirculation (EGR)3

80% 85% 63% V NOx Tier III Selective catalytic reaction (SCR) 90% V NOx Tier III

PM abatement technologies SOx NOx PM Large Engines? Regulation?

Diesel particulate filter (DPF)4 >90% X -

Diesel oxidation catalyst (DOC)5 70-90% X -

Electrostatic precipitator (ESP)6 85% X -

*1 Lloyd’s Register (2012)

*2 Entec (2005) except EGR

*3 HERCULES. (Available from: http://www.hercules-b.com/1/article/english/1/2/index.htm)

*4 Technical Bulletin - Diesel Particulate Filter General Information, U.S. EPA.

Available from: http://www.epa.gov/cleandiesel/documents/420f10029.pdf

*5 Available from: http://www.dcl-inc.com/index.php?option=com_content&view=article&id=59

*6 Ariana I. M. et al (2006)

To meet both MARPOL Annex VI Regulation 13 and 14 together, ship owners have various

compliance alternatives to choose from. However, for large marine diesel engines that used

by ocean-going vessel such as container ships, oil tankers, bulk carriers and cruise ships for

propulsion power, there are only limited emission control technologies which can be applied

to these engines, typically range in size from 2,500 to 70,000 kW, defined as Category 3

marine engine under U.S. Emission Standard.

Applications of PM abatement technologies can be found only on smaller tugs, yachts and

ferries and there is still no application on ocean-going vessels available to date. Meanwhile,

there are several kinds of PM particles need to be clearly defined when mentioning the

removal efficiency, let alone some uncertainties of the removal efficiency such as condensed

Volatile Organic Compounds (VOCs).



As for NOx abatement technology, Tier II limits under MARPOL Annex VI can be achieved

by using primary controls, which are currently managed by the new engine development

conducted by engine manufacturers. However, in the scenario of continuing using

conventional petroleum-based fuel oils, only SCR or EGR technology has the potential to

meet MARPOL tier III limits.

EGR system is now under development. It is proven to be one of the potential abatement

technologies to meet tier III limits according to HERCULES research projects. However, it is

still unavailable for commercial uses and needs some more time to be ready for the shipping

industry. The actual operational issues and economical impacts remain unknown.

In conclusion, there are many technologies available for SOx, NOx and PM abatement, but

only some of them are ready to meet current MARPOL Annex VI regulations and can be

installed on ocean-going vessels using petroleum-based fuel oils, namely scrubber technology,

both wet and dry systems, and SCR system.

40 Shih-Tung Shu


4. OPERATIONAL ISSUES AND CASE STUDIES

In this chapter, operational issues for scrubber and SCR technologies are discussed with case

studies. These technologies are chosen here because they are the current exhaust gas

abatement techniques available in compliance with MARPOL Annex VI regulations for large

marine engines. Dimension (space and weight), chemical consumable rate, sludge generation

rate and other operational parameters will be introduced to provide sufficient date for LCCA.

4.1. Wet Scrubber System

Wet scrubber system can be divided into three types, namely open loop seawater scrubber

(SWS), close loop freshwater scrubber (FWS) and hybrid scrubber (HS). There are several

main components for these three systems as listed in Table 4.

Table 4. Main components of wet scrubber systems

SWS FWS HS

Scrubber unit ● ● ●

Water treatment system ● ● ●

Pump equipments ● ● ●

Piping equipments ● ● ●

Sludge tank ● ● ●

Monitoring module ● ● ●

Fan equipments (optional) ● ● ●

NaOH feed module ● ●

NaOH storage tank ● ●

Buffer tank ● ●

Fresh water tank ● ●

Bleed-off holding tank ● ●

HS system has the most complex system among the three, while SWS system is the simplest

one, since there’s no chemical consumables used and less tanks needed for operation.

4.1.1. Scrubber Unit

Scrubber unit is normally constructed of corrosion-resistant materials since it provides an

extreme environment of close contact with water and hot exhaust gas and washwater in wet

scrubber systems is highly corrosive. The space and weight estimations of scrubber unit for

wet system are presented in Figure 14 and Figure 15.



Figure 14. Weight of wet scrubber system

Figure 15. Volume of wet scrubber system

The space and weight estimation is made only for dry equipment weight and single exhaust

gas inlet scrubber system.

The size of scrubber unit mainly depends on the volume of the engine exhaust gas and SOx

removal efficiency, and the weight is subjected to material selection. Different vendors have

their know-how and provide different engineering design. It is hard to predict any accurate

scrubber’s dimension, because it depends on more than one parameter and there are not

sufficient data for marine applications to date. Therefore, the technical footprint provided a

generalized result from various data source and could only be used for estimation.

Maintenance of scrubber unit is mainly periodic visual inspection through maintenance

hatches to check the interior surface and spray nozzles. In normal operation condition, the

42 Shih-Tung Shu


maintenance is minimized. With proper corrosive-resistant material and engineering design

the scrubber unit should be used throughout the system life-cycle.

Some vendors also provide multi-inlet scrubber unit (or so called integrated scrubber) that

more than one exhaust gas sources (engine or boiler) are arranged to be cleaned in the same

scrubber unit. Such arrangement can reduce the weight and space needed than multiple

scrubber units system.

4.1.2. Pumping System

The pump size is proportional to the volume of exhaust gas to provide sufficient washwater

for specific cleaning efficiency. The washwater flow rate in SWS system is around

45m3/MWh, which is higher than 20 m

3/MWh in FWS scrubber system, since the buffering

capacity of seawater is less than the buffering capacity of NaOH dosed water. The power

required for the pump should be sufficient enough to life the maximum amount of washwater

from the sea to the scrubber unit, which is most of time located near to the funnel due to the

bulky size.

The power for pumping system is often regarded as the power consumption of wet scrubber

systems. In Lloyd’s Register’s study (2012), the power consumption is estimated to be 1 to

2% for total engine power scrubbed for SWS system, 0.5 to 1% for FWS system and 0.5 to

2% for HS system (depending on the operation mode).

In Wärtsilä’s brochure (2011), it states that normally there are three pumps installed near the

washwater holding tank for wet scrubber, with two pumps operating and one pump stand-by.

4.1.3. Piping System

Similar to scrubber unit, piping system is normally constructed of corrosion-resistant

materials to prevent corrosion. Experience from corrosion problems for the pilot project has

shown that glass reinforced epoxy (GRE) can be one of the suitable materials for piping

system. GRE piping is also lighter comparing to steel piping and easier to be handled during

installation.



However, due to the material characteristic, GRE piping also needs extra bracketing and lager

bended radius since it is less rigid. GRE piping near to the scrubber unit requires protection

from hot exhaust gas.

4.1.4. Sludge Tank

Sludge generation rate is related to the fuel oil quality. In Wärtsilä’s brochure (2011), the

amount of generated sludge is around 0.1 to 0.4 kg/MWh. Sludge generated from the wet

scrubber system cannot be burned onboard and must be stored until it can be handled properly

by the waste treatment facilities.

The size of sludge tank depends on the sludge generation rate and the continuous operation

days between bunkering.

4.1.5. NaOH Dosing and Storage System

NaOH consumption depends on the concentration of the NaOH solution, operating power,

sulphur content in the fuel oils used and designated SOx reduction efficiency. The dosing

module will control the amount of NaOH automatically depend on the parameters mentioned

above.

Theoretical 50% NaOH solution consumption can be drawn in Figure 16. It indicates the

relations of the parameters and should be used as guidance only.

The size of NaOH storage tank depends on the amount of NaOH needed and can be estimated

from consumption rate and the continuous operation days between bunkering.

44 Shih-Tung Shu


Figure 16. NaOH consumption rate [Wärtsilä 2011]

4.1.6. Bleed-off and Fresh Water Topping System

For FWS system or HS running in close loop mode, a certain amount of washwater needs to

be extracted from the re-circulation to remove the accumulated impurities such as oil and

combustion product sludge and the concentration of sodium sulphate. The extracted bleed-off

could be stored in a bleed-off tank or go directly into the water treatment system depending

on the engineering design. A bleed-off tank may offer flexibility, allowing scrubber operation

even when the washwater treatment system fails, but on the other hand extra space and weight

will be occupied.

The amount of washwater bled off is interrelated to the topping of fresh water, which can

make sure that there is sufficient washwater in the loop and also replenish the lost from water

evaporation. As indicated by scrubber manufacturers, the topping up water flow may be

0.1m3/MWh or even below depending on the sulphur content in the fuel oils used, washwater

temperature, engine load and the temperature of the seawater for cooling system.



4.2. Dry Scrubber System

Using calcium hydroxide (Ca(OH)2) in granulate form instead of water as the cleaning

medium, a dry scrubber system has less components than a wet scrubber. A comparison of the

components in the wet and dry scrubber systems sorted by their functions is listed in Table 5.

Table 5. Comparison of wet and dry scrubber system components

Wet scrubber system Dry scrubber system

Scrubber unit Scrubber unit

Water treatment system -

Pump equipments Granule conveying equipment

Piping equipments Piping equipments

Sludge tank -

Monitoring module Monitoring module

Fan equipments (optional) Fan equipments (optional)

NaOH feed module Control system

NaOH storage tank Fresh granulate storage tank

Buffer tank -

Fresh water tank -

Bleed-off holding tank -

- Granulate supply silo

- Used granulate storage tank

There are two components in the dry scrubber system that cannot be sorted according to the

equipment function in wet scrubber system, namely granulate supply silo and used granulate

storage tank. Granulate supply silo is the storage adjacent to the scrubber unit right before the

close contact with the exhaust stream. Used granulate storage tank will collect all the used

granulate for further disposal or recycle used on-shore.

4.2.1. Scrubber Unit

A scrubber unit in the dry scrubber system can be also called absorber which is full with

granulates during operation. Since the volume of absorber is determined by the exhaust gas

flow rate, i.e. the engine size, the total weight of the scrubber unit equals to scrubber unit

material weight plus the weight of granulates occupying the scrubber. The space and weight

estimations of scrubber unit for dry system are presented as below.

46 Shih-Tung Shu


Figure 17. Weight of dry scrubber system

Figure 18. Volume of dry scrubber system

The estimation here is made base on the average of five engine categories from 450kW to

21600kW provided by the manufacturer. It is assumed that the volume and weight

characteristic from 21600kW to 36000kW remain the same and thus proportional to the

engine power. However, the weight and volume assumption for engine power larger than

21600kW might be over-estimated in this study. The data should only be used for rough

estimation instead of any accurate engineering calculation such as stability analysis.

The falling of granulates inside absorber is slow and lead by gravity, with several centimetres

per day. The speed of exhaust gas is also relatively slow comparing to seawater scrubber,

which can avoid the interior scratching. It is also recommended to blow out the exhaust gas

remaining in the dry scrubber system to prevent corrosion in case the system has to be shut

down for longer duration.



Maintenance of the scrubber unit is mainly periodical inspection on board including visual

check of the monitoring system and all the moving parts such as conveying mechanisms and

valves.

4.2.2. Granulate Conveying System and Power Consumption

Screw conveying system is usually utilized to transport granulates for onshore dry scrubber

applications. Experience has shown that screw conveyer is not suitable for ship application

because the platform is consistently moving and not always level.

Pneumatic conveying system is used now for moving granulates from the fresh granulate tank

to the scrubber unit. The power consumption of pneumatic system is less than the pumps in

the wet scrubber system and it is estimated at around 0.15 to 0.20% of total engine power

scrubbed.

Fresh granulates can be transported by silo road tankers and the ship can be bunkered by the

truck’s pneumatic delivery system or in big bags for small ships. Besides typical granulate

bunkering, the dry scrubber manufacturer is working on designing a special kind of container,

which gives the possibility to store both fresh and used granulate in separate compartments. It

can be handled in the same way as the standard shipping container and mounted in a

convenient location onboard directly connected to the scrubber.

4.2.3. Granulate Consumption Rate

Granulate consumption rate is estimated at a rate of 40kg/MWh to reduce 2.7% sulphur

content in the fuel oils used to 0.10% sulphur content. Bases on a density of fresh granulate of

800kg/m3, the volume needed takes up to 0.05m3/MWh.

The size of fresh granulate storage tank depends on the amount needed and can be estimated

from consumption rate and the continuous operation days between bunkering. A slightly

bigger storage tank is needed for the used granulates since the desulphurization process

increases the density of granulate.

48 Shih-Tung Shu


4.2.4. Granulate Logistic and Recycling

As the only scrubbing medium on board, the delivery of fresh and used granulates is essential.

The vendor points out that granulate handling is available world-wide within a radius of 200

km from all major ports. For supplying, logistic centres are responsible for collecting and

storing up fresh granulates from lime plants and distributing them to the ships at berth. The

means of transportation from points to points is achieved by silo trucks. The disposal of used

granulates is collected the same way as supplying is organized, and will be recycled and

reused for different purposes depending on the amount of sulphur contents.

The used granulates are gypsums and can be reused in many different ways. Some recycling

examples are given like the use for high temperature desulphurization of power plants, use as

a retarding agent of cement plants, use for slag reduction of steel plants and use for soil

remediation of agro-technology companies. Processing the used granulates containing

different amount of sulphur contents into homogeneous form is also possible for designate

recycle destination.

Couple System provides a logistic package that a ship owner only has to pay for the

transportation from the port to the logistic centre of Couple Logistic. The discharge from the

ship to the truck is free. A ten year guarantee can be made between the third company Couple

Logistic and the ship owner to insure the handling of granulates.

The supply and disposal up to 100 tons can be guaranteed on a 24-hour notice, while two

hours are required to load and discharge maximum 50 tons of granulates. Route changing on

short notice less than 24 hours might delay the schedule due to the waiting time of granulate

transportation. (Deutsche Afrika-Linien GmbH, personal communication)



4.3. Selective Catalyst Reaction (SCR)

Selective catalyst reaction (SCR) system normally consists of the following components:

▪ a SCR reactor housing with one or more catalyst block elements

▪ a urea control system (pumping, dosing and injection)

▪ a urea storage tank

▪ a control and monitoring system

▪ a soot/ash blowing system

4.3.1. SCR Reactor

A SCR reactor contains one or more catalyst block elements depending on the engineering

design and exhaust gas volume. The total weight of the SCR reactor equals to reactor casing

material weight plus the weight of catalyst block elements occupying the reactor. The space

and weight estimations of SCR reactor with catalyst block elements are presented as below.

Figure 19. Weight of SCR system

Figure 20. Volume of SCR system

50 Shih-Tung Shu


The estimation here is made base on the average of different engine power categories from

200kW to 21700kW provided by the manufacturer (Wärtsilä 2011). It is assumed that the

volume and weight characteristic from 21700kW to 36000kW remain the same and thus

proportional to the engine power. However, the weight and volume assumptions for engine

power larger than 21700kW might be inaccurate in this study. The data should only be used

for rough estimation instead of any accurate engineering calculation such as stability analysis.

Inside the SCR reactor, temperature of the exhaust gas, normally around 350 degrees, is

crucial for catalyst reaction and it is fuel sulphur content dependent. The typical trade off

between the minimum exhaust temperature and the sulphur content is shown as in Figure 21.

Figure 21. SCR operation temperature [Wärtsilä 2011]

In other word, when the engine starts up, it takes some time before SCR system initiates to

work efficiently. Moreover, minimum working temperature also makes the combination of

wet scrubber less feasible due to the drop of temperature if the scrubber is installed upstream,

while downstream is possible causing the clogging due to high sulphur content remains (it is

suggested to use fuel oils with less than 1.00% sulphur content by manufacturers).

Besides temperature, several factors are important for the effectiveness of SCR system

including the precise ammonia introduced, the mixing condition with exhaust gas and the

quality of porous catalyst block surface. Therefore, a good monitoring system is essential to

keep an eye on the operation condition to avoid high back pressure and ammonia-slip

problems.



4.3.2. Catalyst Block Elements

The catalyst block’s lifespan can vary from two to five years or it is suggested to replace the

block every 20,000 operating hours by some vendors. There are certain condition might

shorten the lifespan such as fouling, plugging and poisoning. Fouling refers to the general

deposition of material which masks the surface of catalyst block and prevents the reactants to

contact with the surface. Plugging is normally not visible from inspection, and it indicates the

plugging of the pores in the block and thereby reduces the contact area. An example of

catalyst block fouling is shown in Figure 22.

Figure 22. Catalyst block fouling [Lloyd’s Register, 2012]

Poisoning means the chemical attack of the active element of the catalyst block and can occur

when the fuel and lubricating oil-related compounds are attached onto the block causing

progressive chemical deactivation. In addition, some cases show that abnormal high

temperature and vibration shock wave can also result in the physical failure of the block and

frame.

Any catalyst block failure may lead to high back pressure, extra fuel oil consumption and

engine wears. It is essential to maintain the block in good condition, thus periodical inspection

should be executed properly. During daily operation, it should be monitored by ship crews

and close contact with the manufacturer is necessary for trouble-shooting.

52 Shih-Tung Shu


4.3.3. Urea Consumption and Storage

The urea consumption rate is interrelated with the engine power, NOx reduction efficiency,

and urea solution concentration. It can be calculated based on the equation below (Wärtsilä

2011).

where

VUREA = Urea solution consumption [l/h]

PENGINE = Engine power outpur [kw] mNO2= NO2 (NOx) emissions reduction [g/kWh]

MUREA = Urea ((NH2)2CO) molar mass [g/mol] = 60.07

MNO2 = NO2 molar mass [g/mol] = 46.01

KSLIP = Ammonia slip constant [g/kWh] = 0.2 CUREA = Urea solution concentration [%]

ρUREA = Urea density [kg/l] =1.1

The capacity of the urea storage tank can be calculated depending on the sludge generation

rate and the continuous operation days between bunkering. The material used for building

urea tank must meet the requirements for storing urea such as stainless steel. The temperature

of the urea solution must be higher than 0°C, therefore insulation and heating might be

requires in some installations.

4.3.4. Soot/ash Blowing System

SCR system is typically installed with a soot/ash blowing system to remove periodically soot

and ash covered on the surface of catalyst block to prevent ammonia slip. A large volume of

high pressured air is blown to cleaning the surface. The required air volume differs from

applications and could be improved by CFD simulation according to some manufacturers.

However, it is worth noting that certain catalyst surface clogging can not be removed simply

from air blowing.



4.4. Technologies Comparison

In order to understand the differences between scrubber systems, a comparison is made with

the following assumptions.

- Total engine power scrubbed :10MW

- Sulphur content of the fuel :3.5% sulphur

- Continuous operation time :1 day (24 hours)

- Some other properties :NaOH 50% solution density (1.515 kg/litre) and

water density (1 t/m3)

The weight and volume needed for scrubber unit and chemical consumable rate are assumed

based on Figure. The comparison of scrubber systems can be listed in Table 6:

Table 6. Comparison of scrubber systems

SWS FWS HS Dry

Scrubber unit weight 20 t (dry equipment) 20 t (dry equipment) 20 t (dry equipment) 130 t (including

granulate inside)

Scrubber unit volume 75 m3 75 m3 75 m3 310 m3

Power consumption 1-2% 0.5-1% 0.5-2% 0.15-0.20%

Chemical consumable no consumable NaOH solution NaOH solution Ca(OH)2 granulate

- Rate 5.7litre/MWh-%S 5.7litre/MWh-%S 15kg/ MWh-%S

- Storage needed 4800 litres (7.3 t) less than 4800

litres (7.3 t)

12.2 t

Washwater flow rate 45m3/MWh 20m3/MWh 20-45m3/MWh no washwater

Sludge generation rate 0.1-0.4 kg/MWh 0.1-0.4 kg/MWh 0.1-0.4 kg/MWh no sludge

Freshwater topping rate no freshwater used 0.1 m3/MWh 0.1 m3/MWh no freshwater used

- Storage needed 24 m3 less than 24 m3

Weight loss 20 t

+ operating seawater

+ other equipment

51.3 t


+ other equipment

less than 51.3 t


+ other equipment

142.2 t

+ other equipment

Zero discharge? No yes yes yes

Increase back pressure? yes yes yes yes

Exhaust temperature? significant drop significant drop significant drop no drop

Corrosion possibility? yes yes yes yes

Combined with EGR? yes yes yes yes

Combined with SCR? no, unless with re-

heater

no, unless with re-

heater

no, unless with re-

heater

yes

Combined with Waste

Heat Recovery system?

yes, scrubber

placed after WHR

yes, scrubber

placed after WHR

yes, scrubber

placed after WHR

yes

54 Shih-Tung Shu


The dry scrubber unit filled with Ca(OH)2 granulate (130 tons) is heavier than the other

system (20t) and needs comparably larger space for installation (310 m3). Nevertheless, the

wet system can weigh much heavier during operation with large amount of seawater filling in

the pumping system either as washwater or cooling water. In addition, the wet scrubber

system is more complex than the dry system. It is very likely that all the systems may have

the same weight with all the equipments installed onboard such as pumps, pipes, tanks and

treatment system.

The power consumption for wet scrubber (0.5-2%) is generally higher than dry scrubber

(0.15-0.20%) since pumping larger amount of water around the ship requires more energy

than conveying granulates from the tank to the silo. Meanwhile, SWS system or HS system

operating in open loop need higher power consumption (1-2%) than FWS or HS system

operating in closed loop (0.5-1%) because higher washwater pumping rate is required to

provide sufficient buffering capacity.

Zero discharge is important for sensitive regions such as ports and estuaries. In addition, even

though many authorities may be expected to accept washwater discharge after proper

washwater treatment meeting the requirements of IMO Exhaust Gas Cleaning System

Guidelines, there might be more stringent regulations imposed by regional, national or local

authorities. For instance, it is indicated recently by Council of The European Union (2012)

that ships in EU waters can use a scrubber operating in closed mode only.

In the current EGR pilot project, a wet close-loop FWS system is used internally to remove

the soot and sulphur content in the exhaust stream before re-entering into the combustion

chamber. Dry system is also possible candidate for internal EGR utilization. To achieve IMO

Tier III limits, an additional SOx abatement technology is required. In this case, all systems

can be combined with EGR since there is neither temperature drop nor any other

incompatibility.

Unlike EGR system, temperature and sulphur content remained are crucial when combining

SCR systems with scrubber systems. As mentioned in the previous chapter, a wet scrubber

system can only be installed before a SCR system and a re-heating system is necessary for

bring back the working temperature of catalytic process, while a dry system can be installed



either before or after a SCR system. Likewise, a waste heat recovery system should be

installed before any wet scrubbing process.

For NOx abatement technology there are only two techniques that are able to meet IMO Tier

III regulations for large marine engine, namely SCR and EGR system. It is still too early to

make any meaningful comparison or comments between the two, since EGR technology is in

its early stage of development.

56 Shih-Tung Shu


4.5. Case Studies

To date, there are more than 25 scrubber system installations on ships including the SWS,

FWS (inclusive of a FWS system implemented inside EGR system), HS, Dry systems and a

CSNOx system which claims that it can remove SO2, NOx and CO2 at the same time using

Ultra Low Frequency (ULF) wave electrolysis treatment. After several years of trial testing

and pilot projects, there are an increasing number of commercialized scrubber installations in

years 2011 and 2012. The scrubber installation list is shown in Table 7.

Public testing reports are available for four of the ships, namely MS Pride of Kent, MS

Zaandam, MT Suula and Ficaria Seaways. A brief introduction to these reports is presented as

case studies in the following sections.

Table 7. List of scrubber installations

System type Installation type Ship name Ship type Engine power scrubbed Year installed Scrubber vendor Ship owner

SWS retrofit Pride of Kent ferry ship 1xAE: 1MW 2005 Wärtsilä P&O

retrofit Zaandam passenger ship 1xME: 8.64MW 2007 Wärtsilä Holland America Lines

retrofit APL Container container ship 1xAE:8MW 2011 Wärtsilä APL England

newbuilding Jolly Diamante ro-ro cargo 4xAE:2MW, 1x Auxiliary Boiler 2011 Wärtsilä Ignazio Messina

newbuilding Jolly Perla ro-ro cargo 4xAE:2MW, 1x Auxiliary Boiler 2011 Wärtsilä Ignazio Messina

newbuilding Jolly Cristallo ro-ro cargo 4xAE:2MW, 1x Auxiliary Boiler 2011 Wärtsilä Ignazio Messina

newbuilding Jolly Quarzo ro-ro cargo 4xAE:2MW, 1x Auxiliary Boiler 2011 Wärtsilä Ignazio Messina

newbuilding HHI Hull 2516 TBN NA NA 2012/2013 Wärtsilä Solvang

retrofit Shahnaz motor yacht NA NA Marine Exhaust Solutions Pietra Ligure

FWS retrofit Suula tanker ship 1xAE:680kW 2008 Wärtsilä Neste Oil Shipping

retrofit Containership VII container ship 1xME:12.6MW 2011 Wärtsilä Containerships Ltd Oy

newbuilding Equinox bulk carrier NA 2012 Wärtsilä Algoma Central Corporation

(EGR close) retrofit Alexander Maersk container ship 10MW 2009 MAN Diesel&Turbo Ap Moller Maersk

Hybrid retrofit Ficaria Seaways ro-ro cargo 1xME:21MW 2010 Alfa Laval DFDS Seaway

retrofit Baru chemical tanker 12MW 2009/2011 Clean Marine Klaveness Maritime Logistics

retrofit Tarago ro-ro cargo 1xME:25MW, 1xAE:6MW 2012 Wärtsilä Wilhelmsen

retrofit Maersk Taurus container ship 1xAE:3.5MW 2012 DuPont BELCO Ap Moller Maersk

retrofit Liberty of the Seas container ship NA 2012 Green Tech Marine Royal Caribbean

retrofit NA NA NA NA Alfa Laval Spliethoff Group

Dry retrofit Timbus cargo ship 1xME:3.6MW 2009 Couple Systems Braren Reederei, Kollmar

CSNOx* retrofit White sea tanker ship 1xME:11MW 2009 Ecospec Tanker Pacific

retrofit Independence of the Seas cruise ship NA 2012 Ecospec Royal Caribbean

*CSNOx is a technology that claims to remove SO2, NOx and PM together with the patented Ultra Low Frequency (ULF) wave electrolysis treatment.

58 Shih-Tung Shu


4.5.1. MS Pride of Kent – SWS system

Installation of an open loop seawater scrubber system on P&O Ferries’ Pride of Kent, as

shown in Figure 23, was a project proposed by Hamworthy Krystallton Ltd. (HKL, now a

Wärtsilä company) in 2005. The costs of the scrubber and installation were covered by HKL

for demonstration reason of their product.

Figure 23. MS Pride of Kent.

Available from: http://www.shipspotting.com/gallery/search.php?query=Pride+of+Kent&x=35&y=12

A 1MW auxiliary engine was equipped with the SWS system, but due to the constraints of the

ship’s fuel system and the engine power scrubbed was merely a small part of the total

installed power, it was not used as the compliance meeting IMO Annex VI regulations. The

scrubber was installed using much of the equipment framework from a previous unsuccessful

scrubber project and some addition modification of the ducting was also made. Glass

reinforced epoxy was used for piping due to the corrosion problems.

After more than 30000 operation hours, the results show that a 98% reduction rate of SOx and

a 70% reduction rate of PM can be achieved. The rate of sludge generation rate is

approximately 10kg per operation day. The scrubber system is now removed after six years

testing at the end of the pilot project.



4.5.2. MS Zaandam– SWS system

MS Zaandam is an existing ferry ship belonged to Holland America Line as shown in Figure

24. The SWS system installation project was initiated to treat the exhaust from one of five

main engines on the vessel in November 2006 by the Puget Sound Clean Air Agency

(PSCAA) and it was financed by the United States Environmental Protection Agency

(USEPA), Holland America Line, Environment Canada, Puget Sound Clean Air Agency,

British Columbia Clean Air Research Fund, Port of Seattle (Washington) and Port Metro

Vancouver (British Columbia, Canada).

Figure 24. MS Zaandam. Available from: http://www.shipspotting.com/gallery/search.php?query=Zaandam&x=39&y=5

An open loop seawater scrubber by Hamworthy Krystallton Ltd. was first installed in April

2007 and followed up with piping and instrumentation installations during ship operation

from April to August 2007. Monitoring of SWS system performance started in August 2007.

This pilot test installation aimed at answering questions about the SWS system, such as

emission reduction efficiency, washwater flow rate, concentration of washwater discharge,

sludge generation and hazardous waste classification.

An emission control evaluation was conducted by the Emissions Research and Measurement

Division (ERMD) of the Environmental Technology Center – Environment Canada in

60 Shih-Tung Shu


September 2007. The results show that an average removal rate of SO2 (75%) and PM (57%)

can be achieved on the 8.64MW 4-stroke engine using 1.77% sulphur content heavy fuel oil,

equivalent to 0.5% sulphur fuel oil used.

More than 4000 operating hours of data were collected and several future works were

indicated such as the installation of a continuous engine emission monitoring device and an

additional system to remove the soot from the wash water discharge and personnel training on

scrubber operations.

4.5.3. MT Suula– FWS system

The idea of FWS system installation was initiated in 2005 leading by scrubber manufacturer

Wärtsilä. A medium speed auxiliary engine (680kW) onboard a tanker ship “Suula”, as shown

in Figure 25, was chosen to test the close loop freshwater scrubber system. In 2008, the

scrubber was installed with water treatment system, sludge tank and NaOH storage tank, and

began the testing phase in November. Glass reinforced plastic (GRP) is also used for piping

equipments because of its material characteristic of corrosive-resistance.

Figure 25. MT Suula. Available from: www.shipspotting.com/gallery/photo.php?lid=160036

Several testing targets were set into different testing segments such as reduction efficiency

test, system start-up test, noise test, sledge test, bled-off washwater test, corrosion test and so



on. Special measurements were conducted by several subcontractors. Fuel, gas and water

samples were taken from the FWS scrubber system during the test period for further analyses

in the laboratories.

According to the FWS pilot test public report, the SO2 removal rate is more than 99% under

four different scrubber load levels (8 %, 40 %, 70 % and 100 %) and 30 to 60% of PM

removal can be achieved. In addition, effluent tests show that FWS system can meet the limits

for pH, turbidity, PAH and nitrate defined in IMO resolution MEPC.184 (59).

Based on the sledge test, the results indicate that the sludge wastes generated from the close

loop system can be disposed in the same way as other oil sludge generated from engines and

further treated in other reception facilities.

The power consumption of FWS system is said to be around 0.50% of the engine power

scrubbed during the testing operation period, with freshwater consumption rate of 1 metric

tonne per hour and chemical consumable rate of 130 litre NaOH solution per hour.

4.5.4. Ficaria Seaways – HS system

In 2008, DFDS Seaway and scrubber manufacturer Alfa Laval tested a hybrid scrubber

system onboard the ferry Ficaria Seaways with the cooperation of Denmark’s environmental

protection agency. The scrubber is in operation since June 2010 in route between Goteborg -

Immingham (1trip per week), Immingham – Goteborg (2 trips per week), Goteborg – Brevik

(1 trip per week), and Brevik – Immingham (1 trip per week).

Based on the previous experience of a land-based pilot test, a 21 MW 2-stroke engine by

MAN Diesel & Turbo on-board Ficaria Seaways was equipped with the hybrid scrubber

system by Alfa Laval which is capable of operating in both open and closed loop mode. A

scrubber bypass was installed to provide the flexibility of running compliant fuel. A photo of

Ficaria Seaways is shown in Figure 26.

62 Shih-Tung Shu


Figure 26. Ficaria Seaways.

Available from: http://www.marinetraffic.com/ais/shipdetails.aspx?mmsi=220464000

The power consumption of HS system is estimated to be around 1.4% of total engine power

scrubbed (1% due to pumping and 0.4% due to the increased back pressure). Using high grade

stainless steel (seawater resistant) as the construction material, the scrubber unit weighs 32

tonne (including water) in operation. The system is designed to treat up to 192,000 kg/h of

exhaust gas from the 21 MW MAN engine. In addition to the scrubber unit installed, around

200 meters of piping equipment was also installed with diameters varying between 300 and

500 mm.

The public test report of HS system conducted by Danish Environmental Protection Agency

onboard Ficaria Seaways shows that the SO2 removal rate can be achieved up to almost 100%

in both open and closed loop mode using fuel oils with 2.70% sulphur content . 2 to 4 m3 of

water per hour is discharged in freshwater mode, while 1000 m3 of water per hour has to be

discharged in seawater mode. Even with this large amount of water discharged, the turbidity

measurement and PAH content are still below the limits in the MEPC guidelines

Based on the impact assessments for water discharge study regarding sludge sample tests by

Danish Environmental Protection Agency, the sludge generated in close loop freshwater mode

has the concentration of nickel, vanadium and THC that it is classified as hazardous waste and

must be treated and disposed of accordingly when transported to land. There are suitable

facilities for hazardous waste reception, handling, transport, treatment and disposal of in



Danish ports. The price of sludge handling was estimated in different scenario within Danish

ports.

4.5.5. SCR System Installation

There are more than 600 SCR ship installations since 1987 according to a SCR installation list

submitted to IMO by corresponding groups. A statistic graph presenting the total engine

power of SCR installation over the past two decades and a graph showing the number of

installation are shown as below in Figure 27 and Figure 28.

Figure 27. Total engine power of SCR installation

Figure 28. Number of SCR installation

64 Shih-Tung Shu


When SCR technology was first introduced into the shipping industry, only small engines

with engine power below 1MW were installed. In 1998, larger engines were installed with

SCR systems and the combination between main engine, auxiliary engine and boiler has

increased, but mostly in the range of 10MW to 20MW.

With the upcoming stringent NOx limits, it can be foreseen that there will be an increasing

demand for SCR technology since it is a mature and well developed technology with many

successful marine applications.



5. INSTALLATION IMPACTS

Scrubber technology is one of the proven exhaust gas treatment techniques, but there is

insufficient empirical data from marine applications. Impacts of scrubber system are typically

ship owner’s doubts regarding technical and economical aspects, while local authorities and

concern more about environmental influences. Technical and environmental impacts are

introduced in this chapter, while the economical impacts will be discussed in Chapter 6.

5.1. Technical Impacts

5.1.1. Space

Not only the bulky scrubber unit but also all the other major components need space to fit in

the already optimized space onboard in retrofitting cases. The capacity required for the

scrubber unit depends on the engine size, the number of exhaust inlet, engineering design and

scrubber type.

Due to the characteristic of scrubbing process, most of the scrubber units are installed near the

chimney. In some retrofitting scrubber installations, the chimney casing has to be removed

either for installation opening or there is simply not enough space and a new casing design is

needed. For ships like cruise ship, the aesthetic appearance also has to be considered since a

bulky chimney casing might not look too good comparing to the sleek ship.

Other than the huge scrubber units, other treatment systems also take up space onboard. For

wet scrubber systems, washwater treatment systems, freshwater tank or caustic soda tank,

sludge tank, pumps and dosing control panel all need space to settle; while for dry scrubber

systems, the place for the fresh and used granulates has to be considered. Although in

comparison to the tricky task for scrubber unit, the space for other units is not so hard to find

onboard the ship.

For scheme B scrubber systems, onboard monitoring system is required to ensure the

regulation compliance, which consists of very sensitive probes and vulnerable electrical

control and analysis equipment. Some harsh environments with consistently vibrating

66 Shih-Tung Shu


condition might not be perfect for monitoring systems and thus need more attentions

regarding maintenance and reliability check.

Access for maintenance is often neglected in facing such tight space plan. In some extreme

cases, some crews were injured during the maintenance or replacement of the equipment due

to the lack of access space consideration. This problem could be hidden until reported and

might need medications, thus becomes one of the hidden costs for scrubber installation.

It is much easier for new-built ships with scrubbers than retrofitting. However, it is

challenging and important in both cases for engineers to take all the requirements into

consideration.

5.1.2. Weight

Weight of scrubber system consists of the dry weight of all equipments, modification for extra

piping, casing and structural reinforcement and water or consumables used. Depending on the

scrubber type and equipments provided by different vendors, a scrubber system can weigh up

to hundreds tons. It will for sure take up the weight capacity of the ship, and sometimes

reducing ship stability.

Installing scrubber systems leads inevitably to cargo loss. It will have different economical

impacts on various ship types, depending on the percentage of cargo loss to the whole cargo

capacity. In case of cargo or container ships’ installation, the cargo loss can be calculated in

turns of money loss.

For stability reason, the operational weight of all scrubber systems and the location of

installation should be carefully considered. It may not be available for retrofitting all the ships.

5.1.3. Operation Mode

Scrubber systems need to be switched on and off when traveling between ECAs and non-

ECAs. Either the scrubber unit can be operated in dry mode, without the scrubbing process, or

the exhaust bypass is required, which can also provide alternatives in the case of scrubber

system failure.



In the scenario of scrubber system failure, ship should continue sailing by alternative means

and stay complied in accordance with the regulations, for instance switching to ultra-low

sulphur fuel or marine gas oil. Redundancy of compliance alternative should be considered

onboard even with scrubber systems installed. However, how much compliant fuel should be

stored to be regarded as sufficient in the case of main engine scrubber system’s failure? Do

the engines have the ability to use the alternative means directly? These challenges should

also to be considered in the scrubber system design stage.

The likelihood of scrubber system failure depends on the reliability of the system components

and the redundancy available in the engineering design. For example, in the event of a single

pumping unit failing for wet scrubber system, redundant pumping unit can be switched on

immediately to avoid the overall system failure. Other areas where redundancy can be

constructed include the exhaust gas and washwater monitoring systems.

For both wet and dry scrubber systems, the exhaust gas remaining in the pipes might cause

corrosive problems if the system is off for days. It is recommended to have fans installed and

all the exhaust gas should be pumped out while the ship is off-hired.

5.1.4. Chemical Usage

Chemical usage onboard is related to two crucial factors, namely the amount of chemical

consumable needed and the safety for chemicals. The amount of consumables will play an

important role in scrubbing efficiency and the weight and space taken up for storage, which

are ship- and machined-related; while the safety for chemical usage should be addressed for

the crew onboard.

Except for open loop seawater scrubber system (or hybrid runs in open loop), either sodium

hydroxide or calcium hydroxide are needed to take down the sulphur from exhaust gas.

Depending on the chemical bunkering interval, the rough amount of consumables needed for

one voyage can be calculated according to the consummation rate. Redundant consumables

should also be added to avoid delay of consumable refilling.

68 Shih-Tung Shu


Availabilities of chemical consumables in ports should be confirmed. In case of route

changing with short notice, it may not be possible for the chemical bunkering which will lead

to schedule delay with scrubber system not being able to operate.

The quality of chemical source is as important as ship fuel. Without the quality control of the

chemical consumables, it might cause unpredictable shut-down or non-compliance situation.

Appropriate protection for chemical should be installed near the storage tank. For examples,

sodium hydroxide in a 50% solution is corrosive to the skin and may cause severe burns, even

with short exposure. Protective goggles or clothing and eye wash shower station should be

considered. Besides, solutions of mists of sodium hydroxide may also cause damages to the

eyes, resulting in vision impairment or even blindness. General or local ventilation can be

provided to control the airborne levels below the exposure limits.

Crew training for handling consumables as well as solid waste onboard should be given, or at

least the knowledge should be passed down among crew members. Solid wastes from the wet

system consist of concentration of heavy metals. It should be properly handled by the port

facility and should not be incinerated onboard.

5.1.5. Exhaust Gas Handling

Exhaust gas treatment technologies increase intrinsically the exhaust backpressure for engines.

Engines can normally permit a certain range of backpressure without generating problems,

such as accelerated wear, reduced maintenance internals, reduced power and increased fuel

consumption. If the backpressure increases to a level outside of tolerable range, it can be

reduced by installing an induced draft fan.

When installing scrubber systems, main engine, auxiliary engines and sometimes large boiler

need to be considered as the sources of exhaust gas. In the case of single inlet system, at least

two scrubber units have to be introduced. Some vendors propose the integration scrubber

systems (multi inlet system), that it claims to have the same removal efficiency while greatly

reduce the footprint of the systems by combining two or more exhaust gas inlets into one

scrubber unit. The cost of multi inlet scrubber system might also be lower than the single inlet



scrubber system with respect to the same vessel. The schematic drawing of single and multi-

inlet scrubber system can be shown as in Figure 29.

Figure 29. Single and multi-inlet scrubber system

However, some technical and operational issues should be taken in to good consideration

when using multi inlet scrubber system. Marine engines do not operate normally at constant

load and therefore the combination of exhaust gas volume will also change significantly. It is

important how the exhaust gas is mixed from various sources before entering one single

scrubber unit. Intertanko’s report (2012) indicated that by using one scrubber for all engines

requires a very large scrubber unit to ensure the backpressure won’t exceed the tolerable

operation range. Additionally, it may require a redundancy system if the integrated scrubber

fails.

Table 8. Comparison of multiple separate and multi-inlet scrubber system

CapEx OpEx Weight Space System Reliability

Multiple Separate Scrubbers Higher Same Heavier Larger Higher

Multi-inlet Scrubber Lower Same Lighter Smaller Lower

For ships categorized in NOx Tier III, not only scrubber systems but also NOx abatement

technologies should be considered for installation. When Selective Catalytic Reaction (SCR)

device, considered to be the most efficient secondary method available, is installed with

scrubber systems, the compatibility needs to be double-checked.

70 Shih-Tung Shu


There are two crucial factors for SCR, namely the working temperature and the sulphur

contents limit for catalytic block poisoning. In order to prevent oxidation of sulphur dioxide

with reduction catalyst materials, fuel with sulphur content of less than 1.00% should be used.

When the exhaust gas is first introduced to SCR before scrubber system, without scrubbing

down the sulphur from HFO, clogging of the catalyst block is foreseeable. In the case of

installing downstream of the scrubber system, for dry scrubber system it does not decrease the

exhaust gas temperature and it is thus compatible for installing SCR directly after; while the

exhaust gas temperature is significantly reduced, and a re-heater is required to bring the

temperature back for efficient NOx removal. The relation of abatement technology

compatibility can be shown in Figure 30.

Figure 30. Abatement technology compatability

5.1.6. Noise Attenuation

In some cases silencer will be replaced by scrubber units since it has most of time the good

location and space on the way out to the chimney. Most of vendors claim their scrubber units

can work as silencer, but without indicating whether they can cover up what silencer used to

do or not. For better and comfortable environment onboard not only for crews but also for

passengers, it should be also carefully considered in both new-built and retrofitting design

stage.



5.1.7. Crew Training

There are various equipments onboard which should be taken good care of by the crews.

Without knowing how the exhaust gas treatment technologies work, any type of EGT system

would be another black box. Therefore, in the time of EGT system trouble shooting, most of

engineers would rather choose to turn it off than fixing the problem, since ships can still

operate without cleaning the exhaust gas. It is suggested to build up the basic concept of how

EGT systems work for crews.

72 Shih-Tung Shu


5.2. Environmental Impact

5.2.1. Washwater Discharge Criteria

The IMO Exhaust Gas cleaning System Guidelines regulates the washwater discharge from

wet scrubber system. PH value as a measure of acidity, polycyclic aromatic hydrocarbons

(PAHs) as a measure of harmful oil components and turbidity as a measure of particulate

content are the three criteria needed to be monitored continuously for comparisons with the

quality of the receiving water.

Typical washwater instrumentation consists of three checking point, namely at the washwater

inlet, after washwater treatment plant and before pH correction and at the point after pH

correction before discharge back into the sea. When the seawater first enters into the pumping

system, pH, PAH, turbidity and salinity values will be measured as the reference.

The pH value of seawater is normally around 8 to 8.4. In some regions such as Baltic Sea,

there is relatively low alkalinity, which has lower efficiency for sulphur removal. There are

still debates among the use of open loop scrubber systems, which discharge the treated

washwater back into the ocean. Some claim that it should not take the sulphur content back

directly into the environment; while some others claim that sulphur does already exist in the

environment in various forms.

In European council directive 1999/32/EC amendment as regards the sulphur content of

marine fuels, it is mentioned that “…A general cap does not allow the use of marine fuels

with a sulphur content of more than 3.5 % by mass within member states territory, with the

exception of fuels used by vessels with alternative exhaust gas treatment systems, the so-

called scrubbers, operating in closed mode.” It might indicate that only close loop scrubber

systems can be used for wet scrubber system.

5.2.2. Sludge Disposal

Wet scrubber systems generate sludge in a rate of approximately 0.1 to 0.4 kg/MWh. The

composition of the sludge is mainly oil hydrocarbons, ash and metals. The waste



classification still remains unknown since there are not so many scrubber installations and not

enough samples for the data base. Many vendors believe that the wet scrubber generated

sludge can be treated as other engine generated oil sludge, but cannot be incinerated onboard.

However, a recently investigation points out the concern for scrubber generated sludge and its

disposal.

In 2012, Danish Environmental Protection Agency (Kjølholt J. et al, 2012) compared the

characteristics of scrubber sludge from literature reviews and practical investigation of an

existing wet scrubber system to find out possible impacts of scrubber water discharges on the

marine environment. It indicates that the sludge generated in circulation mode contained high

levels of sulphur, petroleum hydrocarbons (THC) and vanadium, nickel and cooper. Due to

the high concentration of nickel, vanadium and THC the sludge should be classified as

hazardous waste and must be treated and disposed at port facility if available or corresponding

waste treatment facilities.

Table 9. Close loop wet scrubber sludge sampling [Kjølholt J. et al, 2012]

Chemical substance Limit value (mg/kg) Sludge waste (mg/kg)

Nickel (Ni) 1000 5400

Vanadium (V) 10,000 12,000

Total petroleum hydrocarbons (THC) 1000 111,000

The sludge disposal cost was estimated that transfer of 2 m3 liquid waste from the port to the

chemical treatment company needs 2 to 3 hours and costs 1000 DKK per hour (~134€/hour)

for transportation in Port Copenhagen (Kjølholt J. et al, 2012). With the assumption that a 10

MW scrubber operates 270 days per year with the sludge generation rate of 0.25 kg/MWh -

%S, total 9 tons of sludge waste treatment will be created and cost 11,515€ per year for

proper disposal.

5.2.3. Scrubber End-of-life

It is far too early to foresee the end-of-life for the novel scrubber technologies, but ship

owners should be aware of any possible impacts. Hong Kong International Convention

(HKIC) will come into force in the future regarding the ship recycling issue. Scrubber

systems, most of time with tailor-made design, will be part of the ship and the equipments

74 Shih-Tung Shu


from the systems will not be easily re-sold unlike the other more common equipments such as

engines.

The end-of-life expenditures normally include disposal inspections, pre-cleaning, disposal and

demolition cost. Typically the life-span of scrubber system can be estimated to be longer or at

least equivalent to the life-span of the ship itself. Therefore, the most possible case is that the

ship is decommissioned with the scrubber system instead of decommissioning only the

scrubber system while the ship continues to stay in operation. The cost of recycling the

scrubber equipment is thus interrelated with the practice and regulation of ship recycling.

The Hong Kong International Convention for the Safe and Environmentally Sound Recycling

of Ships was adopted in May 2009 and it may enter into force 24 month after the entry into

forces conditions are met. Once HKIC enters into force, it will regulate ship recycling issues

such as the reselling of ship scrapping material that may contain environmentally hazardous

substances including asbestos, heavy metals, hydrocarbons, ozone-depleting substances and

so on.

Before the ship is sent for recycling, it will be requested to carry out an investigation of any

hazardous materials that are listed in the HKIC Inventory of Hazardous Materials. Since the

scrubber system installed onboard is part of the ship, if any material used for scrubber system

containing these hazardous substances mentioned above exists, it must be taken good care of

and the high pre-cleaning and demolition costs can be expected.

Most scrubber vendors are aware of HKIC Inventory of Hazardous Materials which has not

come into force yet and claim that none of the hazardous material is used throughout the

scrubber system’s lifetime. In this case, ship owners will have greater responsibility to know

what kind of materials is used not only for the scrubber system, but also for all the equipments

onboard.



6. LIFE CYCLE COST ANALYSIS

Four different vessel / route combinations are picked to demonstrate the impacts of engine

size, time travelled inside ECA-SOx, and continuous operation days inside ECA-SOx on the

life-cycle cost analysis.

To focus on the impacts, the assumption is made that only one single-inlet exhaust gas

scrubber system is installed to clean the exhaust stream from one main propulsion engine. The

cases of the multi-inlet scrubber system are not discussed in the analysis.

A transpacific 4,000 TEU containership with 60,000 DWT travelling between Europe and

North America is equipped with the scrubber system. The propulsion engine power is 36 MW

and it uses 80% average engine load to maintain speed. Since most of the time it travels

across the Pacific Ocean, total time spent inside the ECA-SOx is estimated at 30% per year,

while the continuous operation days inside the ECA-SOx are assumed to be 3 days.

A 7,500 DWT passenger ship with 2,500 passenger capacity travelling in EU waters is

equipped with the scrubber system. The propulsion engine power is 16 MW and it uses 90%

average engine load to maintain speed. Total time spent inside the ECA-SOx is estimated at

70% per year since the ship would divert part of its course outside of the ECA-SOx. The

continuous operation days inside the ECA-SOx are assumed to be 2 days.

A 1,500 TEU Ro-pax with 400 passengers travelling between United Kingdom and Norway

plans to install a scrubber system. The propulsion engine power is 12 MW and it uses 90%

average engine load to maintain speed. The ship spends all the time inside ECA-SOx and it

operates continuously for only one day.

A 37,000 DWT transpacific tanker travelling between Europe and North America is installed

with the scrubber system. The propulsion engine power is 10 MW and it uses 80% average

engine load to maintain speed. Total time spent inside the ECA-SOx is estimated at 50% per

year since the ship cruises across the Pacific Ocean and spends longer time inside North

American ECA-SOx. The continuous operation days inside the ECA-SOx are assumed to be 5

days.

76 Shih-Tung Shu


6.1. Baseline Scenario

The baseline of the life-cycle cost analysis is defined as no abatement technology scenario

that only MGO is used for propulsion engine. The life-cycle cost equals to the total MGO

consumption over 15 years of analysis.

A baseline of life-cycle cost is provided as in Table 10 for four different ship type and

operation profile combinations. It is assumed that all ships have the same days of operation

per year, the same engine fuel consumption rate, and the same scrubber life-span.

The cost of switching fuel oils without installing any abatement technology to meet the IMO

SOx limits can be calculated by the price spread between the HFO and MGO and the total

fuel consumption per year.

Table 10. Baseline of four vessel types

Container Passenger Ro-Rax Tanker

Engine Power 36 MW 16 MW 12 MW 10 MW DWT 60,000 7,500 27,000 37,000 Cargo capacity 4000 TEU - 1500 TEU - Passengers capacity - 2500 400 - Average Engine Load 80% MCR 90% MCR 90% MCR 80% MCR ECA-SOx time 30% 70% 100% 50% Continues Operation Days in ECA-SOx 3 days 2 days 1 day 5 days Days of Operation (per year) 270 days 270 days 270 days 270 days

Life-span 15 years 15 years 15 years 15 years Date of Installation 2014 2014 2014 2014 Engine Fuel Consumption 173g/kW-hr 173g/kW-hr 173g/kW-hr 173g/kW-hr Total Fuel Used (per year) 9686 tons 11300 tons 12107 tons 4484 tons Cost of HFO (per metric ton) 591 USD 591 USD 591 USD 591 USD Cost of MGO(per metric ton) 925 USD 925 USD 925 USD 925 USD Price Spread (MGO-HFO) 334 USD 334 USD 334 USD 334 USD Exchange rate 1.3 USD/€ 1.3 USD/€ 1.3 USD/€ 1.3 USD/€ Cost of Baseline (per year) 2,488,557 € 2,903,231 € 3,110,568 € 1,152,043 €



6.2. LCCA Framework

6.2.1. Capital Expenditures

For each vessel’s capital expenditures, it can be divided into five subcategories, namely

equipment acquisition cost, engineering design cost, installation / commissioning cost,

documentation / training cost and installation off-hire cost.

The cost data of scrubber equipment are not as transparent as other abatement technologies

such as SCR since scrubber technologies are still evolving rapidly in many different ways and

there is still fierce competition between manufacturers. Furthermore, each scrubber

installation is a tailor-made design for every individual ship and under different engineering

designs depending on ship owner’s requests.

It is relatively difficult to generate any accurate and absolute estimation. However based on

scrubber vendors’ press releases, brochures, public reports and studies, it is still possible to

have a general idea of the capital expenses for scrubber systems in the past few years. The

cost data from various sources are collected with respect to engine size despite of the scrubber

type as shown in the graph below. (Alvestad T. R. in 2011, Bosch P. et al. in 2009, Grebot B.

et al. in 2010, Leigh-Jones C. in 2009, Nikopoulou Z. in 2008, Reynolds, K. in 2012, Ritchie

A. et al. in 2005 and Stavrakaki A. Et al. in 2009)

Figure 31. Cost information of scrubber system

78 Shih-Tung Shu


The linear cost estimation (in red) results from the cost estimation in terms of average cost per

kW from several study reports. Some of the cost data are merely found in a news article or

press release without any specific statement regarding scrubber system types or which of the

cost items such as equipment acquisition cost, engineering design cost, installation cost,

documentation/training cost or installation off-hire cost is included. Nevertheless, a rough

range of scrubber costs varying from 1 million USD to 4 millions USD can be found. In the

following table, cost estimations can be shown for the scrubber equipment cost only.

Table 11. Scrubber equipment cost

(USD)* SWS FWS HS Dry

36 MW 3,100,000 3,850,000 3,600,000 3,770,000

16 MW 2,900,000 3,600,000 3,120,000 2,780,000

12 MW 2,000,000 2,500,000 2,220,000 2,615,000

10 MW 1,800,000 2,150,000 1,920,000 1,870,000

3 MW 1,300,000 1,850,000 1,560,000 1,250,000

1 MW 1,000,000 1,750,000 1,260,000 920,000

*Equipment cost only, without installation, engineering design and documentation

The table is listed base on Glosten’s estimation in 2011 for wet scrubber system (FWS, SWS

and HS), while the cost of dry scrubber system is provided by the vendor with the author’s

normalised estimation for specific engine power. Actual prices for scrubber systems must be

obtained directly from the scrubber manufacturers for specific design requirements.

Costs other than equipment cost are estimated based on percentage of the equipment cost: 9%

for engineering design cost, 80% for installation/commissioning cost and 2% for

documentation/training cost. The installation off-hire cost can be either estimated as 1% of the

equipment cost or calculated from the installation duration and rate off-hire loss. The total

capital expenditures and cost items can be listed in Table 12.

Table 12. Capital expenditures and cost items

Capital Expenditure Total = 1.92 A or 1.91A +B

Equipment Equipment capital cost [€] = A

Installation/Commissioning Equipment capital cost [€]* Estimation in percentage [%] = 0.8 A

Engineering Design Equipment capital cost [€]* Estimation in percentage [%] = 0.09 A

Documentation Equipment capital cost [€]* Estimation in percentage [%] = 0.02 A

Installation Off-hire Loss Loss of off-hire [€/day]* Installation time [days] = 0.01 A or B



Without sufficient exact cost data from the actual installation, there is uncertainty of the cost

percentage estimated. The total capital expenditures are in rough order of magnitude and

should be used only in this study.

6.2.2. Operational and Maintenance Expenditures

Operational and maintenance expenditures can be divided in the following subcategories as

shown in the table. The total O&M expenditures are different from each scrubber system and

can be added up based on various cost items.

Table 13. O&M expenditures and cost items

O&M Expenditures Total = SWS=

FWS=

HS=

Dry=

C+D+E+F+G

C+D+E+F+G+H+I

C+D+E+F+G+H+I

C+D+E+F+J+K+L

Scrubber power cost Total fuel consumption per annum [MT]

* Power consumption [% of MCR]

* HFO fuel price [455 €/MT]

= C

Labour cost Staff need for scrubber per annum (engineer level) [0.2 staff]

* Labour cost (engineer level) [10,000 €/year]

= D

Maintenance Equipment capital cost [€]

* Maintenance cost estimation in percentage [%]

= E

Loss in freight Minimum capacity loss [TEU]

* Travel schedule [voyages]

* Freight rate [€/voyage]

= F

Sludge disposal cost Total sludge generation per annum [MT]

* Sludge disposal price [200 €/MT]

= G

NaOH cost Total NaOH consumption per annum [MT]

* NaOH price [350 €/MT]

= H

Fresh water cost Total fresh water consumption per annum [MT]

* Fresh water price [2 € /MT]

= I

Granulate cost Total Ca(OH)2 granulate consumption per annum [MT]

* Granulate price [230 €/MT]

= J

Fresh granulate transport Total fresh Ca(OH)2 granulate consumption per annum [MT]

* Fresh handling price [75 €/MT]

= K

Used granulate transport Total used Ca(OH)2 granulate generation per annum [MT]

* Disposal handling price [50 €/MT]

= L

80 Shih-Tung Shu


The fuel oil price is listed in bunkerworld.com IFO380 at 591 USD per metric ton and MGO

925 USD per metric ton in Rotterdam in January 2013. The price difference between HFO

and MGO is 334 USD per metric ton. The rate of current exchange rate is assumed to be: 1

Euro= 1.3 USD.

The operating staff is assumed to be 20% of the potion at an engineer level with an annual

salary of 10,000 € for labour cost since most of vendors claim that very little attention is

needed for the scrubber operation.

Caustic soda prices are volatile and estimated to increase caused by demands from different

industries. Based on the market price in October 2012, an average price of 350 € per metric

ton is assumed for 50% NaOH solution including transportation.

The dry system requires calcium hydroxide in the form of spherical granulate as an operating

resource. The price of spherical granulate is estimated to be 230 € per metric ton provided by

the vendor. The handling costs for fresh and used granulates transportation are estimated at 75

and 50 € per metric ton, respectively.

The freshwater replenishment at ports is simply assumed to be 2 € per metric ton despite of

the fact that there are different tariff at different ports.

Based on Danish EPA’s study, it is suggested that the sludge generated from a wet scrubber

system should be treated as hazardous wastes and transported to the corresponding facilities

by liquid bulk waste truck. A rate of 200 € per metric ton is assumed for sludge disposal. The

assumption might be exaggerated under the condition that it takes at least 2 to 3 hours to

transport the sludge from the port to the waste treatment centre. If any further studies can

prove that the sludge generated is merely normal oil sludge and can be disposed of at port

directly, the price can be much cheaper.

To calculate the total consumption of fuel oils, chemical consumables, freshwater and sludge

generation, more parameters have to be defined and it provides the relationship between

technical parameters introduced in Chapter 4 and total operating hours, as shown in Table 14



and Table 15 for wet and dry scrubber systems, respectively. The alphabets listed in the right

row denote the related cost item as listed in Table 13.

For both wet and dry scrubber systems, the minimum capacity loss in terms of TEU is

estimated only by the total weight loss from the installation since it is the only absolute

measurement despite of the installation positions. Evert 20 metric ton increased by scrubber

system installation is regarded as one TEU freight loss and it is included as one of the cost

items for O&M expenditure to reflect the economical penalty of cargo loss under the

assumptions that there are at least 20 voyages each year and the freight rate of 300 €/TEU is

used.

6.2.3. End-of-life Expenditures

Under the circumstances that the scrubber system is made of none-hazardous materials, it is

estimated that the cost of pre-cleaning and demolition will be offset by the reselling of

scrubber scrapping materials. Thus, the expenditures for end-of-life scenario are assumed to

be zero in this study.

6.2.4. Fuel Escalation and Inflation

This analysis assumes that the fuel price escalates at the rate of 8% annually and uses the rate

of 3% for labour cost inflation. Any cost related to fuel price is also expected to escalate at the

same rate such as the cost of chemical consumables, transportation and disposal.

82 Shih-Tung Shu


Table 14. Wet scrubber system parameters

Parameter Definition

Total ECA operation engine profile [hours] =

Days of operation per annum [days]* 24 [hours/day] * Average engine load per annum [%] * Sailing in ECA [%]

Total fuel consumption per annum [MT] =

Engine size [kW] * Fuel consumption [g/kW] / 10^6 [g/ MT] * Total ECA operation engine profile [hours]

C

Total NaOH consumption per annum [MT] =

Engine size [kW] / 10^3 [kW/MW] * HFO sulphur content [%]*100 * NaOH consumption rate [l/MWh-%S] / 10^3 [l/ m3]* 1.52 [MT/m3] * Total ECA operation engine profile [hours]

H

Total Fresh water consumption per annum [MT] =

Engine size [kW]/ 10^3 [kW/MW] * Fresh water consumption rate [m3/MWh]/ 1 [m3/MT] * Total ECA operation engine profile [hours]

I

Total sludge generation per annum [MT] =

Engine size [kW]/ 10^3 [kW/MW] * Sludge generation rate [kg/MWh]/ 10^3 [kg/MT] * Total ECA operation engine profile [hours]

G

NaOH storage tank capacity needed [m3] =

Engine size [kW]/ 10^3[kW/MW] * Continuous operation days between bunkering [hours] * HFO sulphur content [%]* 100 * NaOH consumption rate [l/MWh-%S]/ 10^3 (l/m3)

Fresh water storage tank capacity needed [m3] =

Engine size [kW]/ 10^3[kW/MW] * Continuous operation days between bunkering [hours] * Fresh water consumption rate [m3/MWh]

Bleed-off holding tank capacity needed [m3] =

Engine size [kW]/ 10^3[kW/MW] * Continuous operation days between bunkering [hours] * Bleed-off flow rate [m3/MWh]

Sludge tank capacity needed [m3] =

Engine size [kW] * Continuous operation days between bunkering [hours] * Sludge generation rate [m3/MWh]

NaOH consumption rate [litre/MWh-%S] =

When 3.5 %S used, NaOH consumption rate [litre/MWh] = 20

When 2.7 %S used, NaOH consumption rate [litre/MWh] = 16

When 1.5 %S used, NaOH consumption rate [litre/MWh] = 8.57

Average: NaOH consumption rate [litre/MWh-%S] = 5.714

Total weight loss [MT] =

Equipments dry weight [MT]

+ NaOH storage tank capacity needed [m3]* 1.52 [MT/m3]

+ Fresh water storage tank capacity needed [m3]* 1.0 [MT/m3]

Total space needed [m3] =

NaOH storage tank capacity needed [m3] + Fresh water storage tank capacity needed [m3] + Bleed off storage tank capacity needed [m3] + Sludge tank capacity needed [m3]

Minimum capacity loss [TEU] =

Total weight loss [MT] / 20[MT/TEU]



Table 15. Dry scrubber system parameters

Parameter Definition Total ECA operation engine profile [hours] =

Days of operation per annum [days]* 24 [hours/day] * Average engine load per annum [%] * Sailing in ECA [%]

Total fuel consumption per annum [MT] =

Engine size [kW] * Fuel consumption [g/kW] / 10^6 [g/ MT] * Total ECA operation engine profile [hours]

C

Total fresh Ca(OH)2 granulate consumption per annum [MT] =

Engine size [kW] / 10^3 [kW/MW]

* HFO sulphur content [%]*100

* Fresh Ca(OH)2 consumption rate [kg/MWh-%S]/10^3 [kg/ MT]

* Total ECA operation engine profile [hours]

J

Total used Ca(OH)2 granulate generation per annum [MT] =

Engine size [kW] / 10^3 [kW/MW]

* HFO sulphur content [%]

* Used Ca(OH)2 generation rate [kg/MWh-%S] / 10^3 [kg/ MT]

* Total ECA operation engine profile [hours]

L

Fresh Ca(OH)2 granulate consumption rate = 7.1 [kg/MWh-%S]

Used Ca(OH)2 granulate generation rate = 8.5 [kg/MWh-%S]

K L

Fresh Ca(OH)2 granulate storage capacity needed [m3] =

Engine size [kW]/1000[kW/MW] * Continuous operation days between bunkering [hours] * HFO sulphur content [%]*100 * Fresh Ca(OH)2 granulate consumption rate [kg/MWh-%S]/ 800[kg/m3]

Used Ca(OH)2 granulate storage capacity needed [m3] =

Equals to Fresh Ca(OH)2 granulate storage capacity needed [m3]

Total weight loss [MT] =

Equipments dry weight [MT] + Absorber wet weight [MT] + Fresh Ca(OH)2 granulate storage capacity needed [m3] * 800[kg/m3]

Total space needed [m3] =

Absorber capacity needed [m3] / 38.5 [m3/TEU]

+ Fresh Ca(OH)2 storage capacity needed [m3] / 38.5 [m3/TEU]

+ Used Ca(OH)2 storage capacity needed [m3] / 38.5 [m3/TEU]

Minimum capacity loss [TEU] =

Total weight loss [MT] / 20[MT/TEU]

84 Shih-Tung Shu


6.3. Technologies Comparison

The life-cycle cost analyses for four vessel/route combinations use the same annual discount

rate of 10%. Net Present Cost (NPC) is calculated for each analysis which includes the life-

cycle cost over 15 years in terms of present money by introducing the discount rate and the

escalation rate.

The life-cycle cost of using MGO is used as baseline to compare with the life-cycle cost of

scrubber systems. The difference between the two can be regarded as the Net Present Value

(NPV) of each scrubber alternative.

Another key factor is the Return of Investment (ROI) which calculates the time needed for the

life-cycle cost of using MGO to offset the capital expenditures incurred in Year 0.



Table 16. LCCA results of vessel/route 1 - Containership

Containership SWS FWS HS Dry

Engine Size 36MW 36MW 36MW 36MW

Fuel consumption 173 g/kW 173 g/kW 173 g/kW 173 g/kW

Average engine load 80% 80% 80% 80%

Sailing in ECA 30% 30% 30% 30%

Days of operation 270 days/yr 270 days/yr 270 days/yr 270 days/yr

Continuous operation 3 days 3 days 3 days 3 days

Life cycle 15 years 15 years 15 years 15 years

Discount rate (per year) 10% 10% 10% 10%

HFO and MGO spread (euro€/MT) 257 € 257 € 257 € 257 €

Total Fuel Used 9,686 tons 9,686 tons 9,686 tons 9,686 tons

Capital Cost (euro€ - Year 0) 4,578,462 5,686,154 5,316,923 5,568,000

Equipment

2,384,615 2,961,538 2,769,231 2,900,000

Installation (80%) 1,907,692 2,369,231 2,215,385 2,320,000

Engineering Design (9%) 214,615 266,538 249,231 261,000

Document (2%) 47,692 59,231 55,385 58,000

Off-hire loss (1%) 23,846 29,615 27,692 29,000

1st Year O&M Cost (euro€ - Year one) 190,359 925,394 923,471 946,270

Weight loss (tons) 56 tons 653 tons 653 tons 456 tons

(% of total DWT) 0.09 % 1.09 % 1.09 % 0.76 %

Net present Cost (euro€ - Present) 6,561,271 16,757,553 16,365,187 16,890,543

MGO Life-cycle cost (euro€ - Present) 29,937,665 29,937,665 29,937,665 29,937,665

Net present value (euro€ - Present) 23,376,394 13,180,112 13,572,478 13,047,122

Return of Investment (year & month) 2yrs3m 4yrs1m 3yrs10m 4yrs1m

Figure 32. NPC and ROI of vessel/route 1 – Containership

86 Shih-Tung Shu


Table 17. LCCA results of vessel/route 2 - Passenger ship

Passenger ship SWS FWS HS Dry








Discount rate 10% 10% 10% 10%




Equipment

2,230,769 2,769,231 2,400,000 2,137,283

Installation (80%) 1,784,615 2,215,385 1,920,000 1,709,826


Document (2%) 44,615 55,385 48,000 42,746

Off-hire loss (1%) 22,308 27,692 24,000 21,373

1st Year O&M Cost (euro€ - Year one) 184,906 898,434 894,742 1,011,188


(% of total DWT) 0.39 % 2.75 % 2.75 % 3.71 %





Figure 33. NPC and ROI of vessel/route 2 – Passenger ship



Table 18. LCCA results of vessel/route 3 - Ro-Pax ship

Ro-Pax ship SWS FWS HS Dry




Sailing in ECA 100% 100% 100% 100%








Equipment

1,538,462 1,923,077 1,707,692 2,011,490

Installation (80%) 1,230,769 1,538,462 1,366,154 1,609,192


Document (2%) 30,769 38,462 34,154 40,230

Off-hire loss (1%) 15,385 19,231 17,077 20,115

1st Year O&M Cost (euro€ - Year one) 252,451 984,726 980,419 1,118,359

Weight loss (tons) 22 88 88 185

(% of total DWT) 0.08 % 0.33 % 0.33 % 0.69 %





Figure 34. NPC and ROI of vessel/route 3 - Ro-ro Ferry

88 Shih-Tung Shu


Table 19. LCCA results of vessel/route 4 - Tanker ship

Tanker ship SWS FWS HS Dry












Equipment

1,384,615 1,653,846 1,476,923 1,438,174

Installation (80%) 1,107,692 1,323,077 1,181,538 1,150,539


Document (2%) 27,692 33,077 29,538 28,763

Off-hire loss (1%) 13,846 16,538 14,769 14,382

1st Year O&M Cost (euro€ - Year one) 176,538 477,249 473,711 474,663


(% of total DWT) 0.05 % 0.80 % 0.80 % 0.48 %





Figure 35. NPC and ROI of vessel/route 4 - Tanker ship



As shown in Table 16 to Table 19 all the analysis results return the positive NPV and the ROI

time ranges from 1 year to 6 year. The dominant factor is the total fuel used inside ECA-SOx

which is highly interrelated with the ROI. The cost advantage of installation a scrubber

system also depends on the price spread between HFO and MGO. In this study, the current

price spread of 257€ per ton is large enough to ensure the foreseeable return of investment by

installing any of these scrubber technologies.

For Vessel 3: Ro-Pax ship, the shortest ROI time (1~2 years) for all the scrubber systems can

be found in comparison to the other vessel types, while Vessel 1: tanker ship has the longest

ROI time (3~5 years) among the four, since the results of ROI time are related to the total fuel

oil used.

FWS, HS and Dry scrubber systems have similar ROI time within one year as shown in

Figure 32 to Figure 35. The NPC between the scrubber systems is dominated by the

equipment cost and O&M cost over the study period.

Among all scrubber systems, the open loop SWS system has the lowest NPC and shortest

time needed for ROI since there’s no chemical consumable onboard to operate the scrubber

and the capital expenditure is often the lowest. However, other systems provide various

flexibilities or compatibility with for example a SCR system. Economical, technical and

ecological impacts must all be taken into consideration during the discussion of selecting

scrubber technologies in the decision making stage.

90 Shih-Tung Shu


6.4. Sensitivity Analyses

Sensitivity analysis provides possible scenarios for factors that are difficult for ship owners to

predict such as the fuel price, escalation rate and inflation rate, while the amount of fuels

consumed inside ECA, the operation days, the freight rate and other factors related to ship’s

operation are normally the well-known design requirements in ship owner’s mind.

To understand the impacts of each factor, an open-loop SWS system installed onboard Vessel

3: passenger ship as discussed in the previous section is chosen for all the sensitivity analyses.

6.4.1. Fuel Price Sensitivity

Predicting the future fuel prise is like looking through a crystal ball, many uncertain factors

exist and they are not visible only until they arrive. Instead of making any prediction, the fuel

price spread in a range from 100 USD to 600 USD is used to analyse the possible

combinations in the future.

By using the 16MW passenger ship with the open loop SWS system installed as example, the

ROI time is calculated based on the time spent inside ECA-SOx and the price difference

between HFO and MGO. The spread sheet is listed as in Table 20.

Table 20. Fuel price sensitivity 100 % 4yrs4ms 2yrs0ms 1yrs4ms 12ms 9ms 8ms

90 % 4yrs11ms 2yrs3ms 1yrs6ms 1yr1ms 10ms 9ms

80 % 5yrs7ms 2yrs7ms 1yrs8ms 1yr3ms 12ms 10ms

70 % 6yrs6ms 2yrs11ms 1yr11ms 1yr5ms 1yr1ms 11ms

60 % 7yrs8ms 3yrs5ms 2yrs3ms 1yr8ms 1yr4ms 1yr1m

50 % 9yrs6ms 4yrs2ms 2yrs8ms 1yr12ms 1yr7ms 1yr4ms

40 % 12yrs5ms 5yrs4ms 3yrs5ms 2yrs6ms 1yr12ms 1yr8ms

30 % never 7yrs5ms 4yrs8ms 3yrs5ms 2yrs8ms 2yrs2ms

20 % never 11yrs11ms 7yrs4ms 5yrs3ms 4yrs1ms 3yrs5ms

10 % never never never 11yrs8ms 8yrs11ms 7yrs3ms

100 USD 200 USD 300 USD 400 USD 500 USD 600 USD

Despite the changing fuel price spread, at least 40% time spent inside ECA-SOx (or total fuels

used over 5000 tons inside ECA-SOx) is suggested to consider installing the scrubber system.



The price spread between HFO and MGO is typically estimated to increase over time. The

larger the price spread, the shorter ROI time can be predicted for the scrubber system.

6.4.2. Fuel Escalation and Inflation Rate Sensitivity

Inflation has a major impact on the labour cost and any labour-related cost such as

transportation and disposal handling. However, the inflation rate and the fuel escalation rate

are normally interrelated. The net outcome of the fuel escalation and inflation rate may cancel

out each other and have a positive or negative effect on the life-cycle cost analysis.

Four combinations, classified as normal, worst, medium and best situations, subjected to the

same 16MW passenger ship are chosen to demonstrate the impact as shown in Table 21:

Table 21. Fuel escalation and inflation rate sensitivity Passenger ship 16MW

Escalation rate Inflation rate

NPV

SWS FWS HS Dry

Normal 8% 3% 28,726,993 € 18,863,293 € 19,616,636 € 18,720,163 €

Best 11% 5% 36,492,699 € 23,921,527 € 24,684,133 € 23,495,512 €

Medium 5% 2% 23,861,776 € 14,855,806 € 15,601,823 € 14,936,376 €

Worst 2% 1% 19,435,254 € 11,678,139 € 12,418,346 € 11,936,160 €

6.4.3. Engineering Design and Installation Sensitivity

The costs of scrubber engineering design and installation are assumed to be subjected to the

equipment cost. The actual cost varies from cases to cases and it is difficult to generalise any

fixed percentage assumption. Therefore, four scenarios with different cost combinations are

listed in Table 22.

92 Shih-Tung Shu


Table 22. Engineering design and installation sensitivity

Passengership 16MW Normal Worst Medium Best

SWS SWS SWS SWS

Capital Cost Total 4,283,077 € Total 4,796,154 € Total 3,747,692 € Total 3,256,923 €

Equipment

2,230,769 €

2,230,769 €

2,230,769 €

2,230,769 €

Installation 80% 1,784,615 € 100% 2,230,769 € 60% 1,338,462 € 40% 892,308 €

Engineering Design 9% 200,769 € 12% 267,692 € 5% 111,538 € 3% 66,923 €

Document 2% 44,615 € 2% 44,615 € 2% 44,615 € 2% 44,615 €

Off-hire loss 1% 22,308 € 1% 22,308 € 1% 22,308 € 1% 22,308 €

Net present Cost 5,483,672 € 5,996,749 € 4,948,287 € 4,457,518 €

MGO Life-cycle cost 34,927,276 € 34,927,276 € 34,927,276 € 34,927,276 €

Net present value 29,443,604 € 28,930,527 € 29,978,989 € 30,469,758 €

Return of Investment 1yr8ms 1yr11ms 1yr6ms 1yr3ms

6.4.4. Labour Cost Sensitivity

The sensitivity of labour cost is analysed by changing all parameters from the engineer annual

salary, operating staff needed and maintenance cost per year for the best and worst scenarios.

Table 23. Labour cost sensitivity

Passengership 16MW Normal Worst Medium Best

SWS SWS SWS SWS

Engineer salary (€/year) 100,000 200,000 50,000 0

Staff needed (staff/year) 0.2 0.5 0.1 0

Maintenance cost (% of unit cost/year) 2% 4% 1% 0.5%

Net present Cost 5,483,672 € 7,005,394 € 5,376,180 € 5,170,334 €

MGO life cycle costing 34,927,276 € 34,927,275 € 34,927,276 € 34,927,276 €

Net present value 29,443,604 € 27,921,881 € 29,551,096 € 29,756,942 €

Return of Investment 1yrs8m 1yr9ms 1yrs8m 1yrs8m

6.4.5. Worst and Best Combination Sensitivity

By combining different sensitivity assumptions, the worst and best scenarios can be created

regarding engineering design, installation, escalation rate, inflation rate, labour cost related

cost and maintenance cost as listed in the table below.

Table 24. Worst and best combination sensitivity



Passengership

16MW SWS SWS SWS SWS

Sensitivity Normal Worst Medium Best

Capital Cost Total 4,283,077 € Total 4,796,154 € Total 3,747,692 € Total 3,256,923 €

Equipment

2,230,769 €

2,230,769 €

2,230,769 €

2,230,769 €

Installation 80% 1,784,615 € 100% 2,230,769 € 60% 1,338,462 € 40% 892,308 €

Engineering

Design 9% 200,769 € 12% 267,692 € 5% 111,538 € 3% 66,923 €

Document 2% 44,615 € 2% 44,615 € 2% 44,615 € 2% 44,615 €

Off-hire loss 1% 22,308 € 1% 22,308 € 1% 22,308 € 1% 22,308 €

Escalation rate 8% 2% 5% 11%

Inflation rate 3% 1% 2% 5%

Engineer salary 100,000 €/year 200,000 €/year 50,000 €/year 0 €/year

Staff needed 0.2 staff/year 0.5 staff/year 0.1 staff/year 0 staff/year

Maintenance cost 2% unit cost 4% unit cost 1% unit cost 0.5% unit cost

Net present Cost 5,483,672 € 6,884,840 € 4,643,048 € 4,329,212 €

ROI 1yr8ms 2yrs1m 1yr6ms 1yr3ms

94 Shih-Tung Shu


6.5. Discussion

The decision of whether to install a scrubber system onboard or not depends on various

factors. One of the dominant factors, usually also what most ship owners concern about, is

whether or not the investment is worthwhile. A LCCA is conducted in this chapter to provide

details of investment items and to analyse the economical factors between different scrubber

technologies.

The results show that ROI time is very sensitive to the total fuels used per year and the price

spread between HFO and MGO. A reasonable ROI time can be expected when the ship

travels 40% of time inside ECA-SOx (or total fuels used over 5000 tons inside ECA-SOx)

when considering a scrubber system installation.

Rather than recommending any specific ship type for a scrubber installation, it is suggested to

first consider the operation profile of the ship. Each individual ship type will have a different

operation profile regarding the travelling region, vessel route and continuous operation days.

Logically for those ships which travel most of time inside ECA-SOx with shorter bunkering

interval such as ferry ships and passenger ships will potentially have a shorter ROI time, since

a larger consumption of compliant fuel is needed while redundant storages for chemical

consumable are less due to the frequent bunkering interval.



and the capital expenditure is often the lowest. Meanwhile, the results also reflect the fact that

even chemical consumables are required for some scrubber types, the costs of chemical

purchasing, handling and transportation can be covered by the price spread between HFO and

MGO in terms of saving. The results can always return the positive NPV under the fuel

assumption of the current bunkering price. Table 24 suggests that the NPC between best and

worst scenarios can have over 2.5 million Euros difference. However, the ROI time increases

merely within 11 months due to the interrelationship between the fuel escalation rate and

inflation rate and the effects brought by high inflation rate are often offset by the high fuel

escalation rate



7. CONCLUSION

Among various SOx, NOx and PM abatement technologies, for large marine diesel engines

that used by ocean-going vessel such as container ships, oil tankers, bulk carriers and cruise

ships for propulsion power ranging in size from 2,500 to 70,000 kW, there are only scrubber,

EGR and SCR systems which can be applied to meet the global SOx and NOx emissions

limits. Since EGR system is still in its early stage in the research project “HERCULES” and

not ready for any commercial application yet, there is insufficient information for conducting

a LCCA between these two possible NOx abatement technologies for MARPOL Annex VI

NOx tier III limits and the life cycle costing of SCR systems is provided in the appendix. The

study focuses thereby only on the scrubber technology.

Ships using a scrubber technology have the advantage to continue using low-cost HFO while

meeting MARPOL Annex VI emission limits. However, higher back pressure, stability loss,

chemical consumables onboard, extra power consumption, cargo loss, environmental impacts

of sludge disposal and washwater discharge and other operational issues can be expected.

Typically a dry scrubber unit full with Ca(OH)2 granulates is heavier than a scrubber unit in

the wet system, but both system may have the same weight during operation since a certain

amount of water is needed for wet scrubbing. To properly estimate total weight loss after

installation, the continuous operation days inside ECA-SOx must be taken into consideration

because sometimes the consumable or water storage can weigh much heavier than all the

equipments on board.

More than 20 marine scrubber installations were made including pilot projects, public testing

and commercial deliveries, and public reports for some of the ships are available online for

examination. Based on the testing results onboard MS Pride of Kent, MT Suula and Ferry

Fiacria Seaway, pollutants from the exhaust gas can be removed efficiently under different

engine loads. There is no concern of washwater discharge according to the sampling tests, but

the sludge disposal of the wet scrubber system requires more researches regarding the high

concentrations of THC, vanadium, nickel. In the scenario that the sludge should be regarded

as hazardous wastes, it can be handled properly as long as there are corresponding waste

96 Shih-Tung Shu


treatment facilities available at the ports or at least transportations to the waste treatment

facilities.

In this study, a life cycle cost analysis of scrubber systems was conducted with discussions of

the operational issues and installation impacts to evaluate the scrubber installation’s cost

throughout its life-cycle systematically. The objective of the analysis is to evaluate a number

of scrubber types for retrofitting or new-built ships and to determine which system can have

the shortest ROI time. The life-cycle costs of the alternative scrubbers are calculated and

compared.

Impacts of the space taken by a scrubber installation are difficult to measure explicitly, since

there are many possible engineering designs to fit the equipment inside the limited space.

However, the weight loss due to scrubber installation can somehow reflect the downsides of

installation. Minimum weight loss is quantified and estimated according to the scrubber unit

weight and extra chemical consumables onboard, but it excludes the other dry equipment’s

weights such as pumps, tanks, piping equipments and extra steel frame if required. The

weight loss takes part in the LCCA as a cost penalty by multiplying the freight rate and the

voyages per year.

For different ship types, it is clear that the weight loss caused by a scrubber installation will

have different levels of impact even there is no significant stability loss. In this study, the 16

MW of passenger ship has up to 3.7% of weight loss with respect to 7,500 DWT, while for

other ship types the weight losses are typically around or below 1% of the ship’s DWT.

The LCCA results show that ROI time is very sensitive to the total fuels used per year and the

price spread between HFO and MGO. To consider a scrubber system installation, a

reasonable ROI time can be expected when the ship travels minimum 40% of time inside

ECA-SOx, or total fuels used over 5000 tons inside ECA-SOx.



and the capital expenditure is often the lowest. Meanwhile, the results also reflect the fact that

even chemical consumables are required for some scrubber types, the costs of chemical

purchasing, handling and transportation can be covered by the price spread between HFO and



MGO in terms of saving. The results can always return the positive NPV under the fuel

assumption of the current bunkering price.

In conclusion, the MARPOL Annex VI regulations are mandatory and the global sulphur limit

cap is coming for sure either in 2020 or 2025. Time is running and the shipping industry must

take actions since there is no option of “non-compliant” and dissuasive penalties can be

expected. As one of the compliant alternatives, scrubber installations demand significant

investment and additional operational and maintenance expenditures are expected. However,

the LCCA results in this study show that it can have lower life cycle costing comparing to

switching over to MGO. Some challenges remain for marine scrubber systems regarding the

large engines’ applications, but it may be improved if more installations can be made in the

near future, just like every novel technology when they were first introduced onboard. Aid for

investment costs from the government will be an important incentive to accelerate the

development.

98 Shih-Tung Shu


ACKNOWLEDGEMENTS

My gratitude is first extended to Lloyd’s Register Hamburg - Central and East European Area

Office, Germany for giving me the internship and all the supports. I would like to thank

especially my mentor Ms. Ramona Zettelmaier for her invaluable guidance, encouragement

and full support in every way. I also truly appreciate all the amazing people in Lloyd’s

Register and in other companies who have given me advices: Mr. Ulrich Foerster, Mr. Bjoern

Schoeneberger, Ms. Kim Tanneberger, Mr. John Bradshaw, Mr. Andy Wright, Mr. Jim Heath,

Mr. Timothy Wilson, Mr. Dimitris Argyros, Mr. Paul Herbert, Mr. Ralf Jürgens, Ms.

Penelope McDaniel, Mr. Michael Finch Pedersen, Mr. Henning Gramann, Mr. Mathias

Magnusson and Mr. Cecilia Ö sterman.

Secondly, I would like to express my deep gratitude to Prof. Philippe Rigo, Prof lionel Gentaz

and Prof. Robert Bronsart for their generous help during my study in Belgium, France and

Germany. It is an honour for me to one of the EMship students.

Finally, my deepest gratitude goes to my beloved parents, my elder brother and all my family

in Taiwan for always supporting me. This master thesis is cordially devoted to all of them.

This thesis was developed in the frame of the European Master Course in “Integrated

Advanced Ship Design” named “EMSHIP” for “European Education in Advanced Ship

Design”, Ref.: 159652-1-2009-1-BE-ERA MUNDUS-EMMC.



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102 Shih-Tung Shu


APPENDIX – SCR Life Cycle Costing

In the scenario that after 2016, ships sailing inside ECA-NOx will need a NOx abatement

system installed to meet MARPOL Annex VI regulations 13. Since SCR system is the only

one alternative available for the market, there is insufficient information to perform a LCCA.

Therefore, only the LCC of SCR system is provided here in the appendix.

This appendix contains the SCR cost data collection and the life cycle costing of SCR system.

There are more than 600 SCR ship installations since 1987 and the cost estimations have been

conducted by several studies as shown in Table 25.

Table 25. SCR cost estimation data collection

Source Engine Category/Range CapEx OpEx Urea Rate Life Span

1.BMT 35 – 75 $ 3-4$ - -

2.Non-road 90 $ - 7.5%BSFC -

3.Entec

Small 64 € 8.6 € 15g/kWh 15 years

Medium 46 € 6.7 € 15g/kWh 15 years

Large 42 € 6.2 € 15g/kWh 15 years

4.AEA 949,000 € 297,000 € - 25 years

5.Turku

Medium 4.5MW to 18MW 40-78 € 5-7.5 € 10%BSFC 15-25 years

Slow 8.5MW to 48MW 47-78 € 5-7.5 € 10%BSFC 15-25 years

Medium 4.5MW to 18MW 32-64 € - 7.5%BSFC -

Slow 8.5MW to 48MW 36-59 € - 7.5%BSFC -

- 2.55 € - 12.5 years

6.H+H 30-50 € 4-5€ - -

7.Solano 2.3MW $472,594 $100,000

*1.BMT Economic Legal Environmental and Practical Implications of A EU system to reduce ship emissions of SO2 and NO2.

*2.Non-road Non-road diesel emission reduction study

*3.Entec Ship emissions, assignment, abatement and market-based instruments

*4.AEA Cost benefit analysis to support the impact assessment accompanying the revision of directive 1999/32/EC on the Sulphur content of certain liquid fuels

*5.Turku Baltic NECA – economic impacts Study report by the University of Turku

*6.H+H EcoMarine Brochure

*6. Solano http://www.baylinkferry.com/ferry/solano-ferry-facts.php

The CapEx estimation can be made based on the SCR cost data collection with regard to six

different engine powers. Retrofitting the SCR system to a ship is assumed to cost 1.2 times



more than designing a new-build ship with the SCR system as listed in Table 26 and Figure

36.

Table 26. SCR CapEx estimation

Newbuild Retrofit

Engine power [MW] CapEx [€] CapEx [€]

1 64,000 76,800

3 192,000 230,400

10 460,000 552,000

12 552,000 662,400

16 672,000 806,400

36 1,512,000 1,814,400

Figure 36. SCR CapEx estimation

Operational cost is calculated based on the total urea used per year with the urea consumption

of 10% of Specific Fuel Consumption (SFC). The maintenance cost is assumed that after

every 1000 operation hours a periodical check and cleaning is needed. During the periodical

maintenance, 6 hours of engineering work are required and it costs 150 € per working hour.

To simplify the O&M assumption, the replacement of catalyst blocks is not included in the

O&M cost calculation, which means that the O&M might be underestimated.

Base on the CapEx and O&M cost estimation, the life cycle costing (LCC) of SCR system

can be forecasted over the designated life-span in line with the four vessel assumptions and

listed in Table 27.

104 Shih-Tung Shu


Table 27. LCC of SCR system installation

Container Passenger Ro-Rax Tanker

Engine Power 36 MW 16 MW 12 MW 10 MW

DWT 60,000 7,500 27,000 37,000

Cargo capacity 4000 TEU - 1500 TEU -

Passengers capacity - 2500 400 -

Average engine load 80% MCR 90% MCR 90% MCR 80% MCR

ECA-SOx time 30% 70% 100% 50%

Continues operation days in ECA 3 days 2 days 1 day 5 days

Days of operation (per year) 270 days 270 days 270 days 270 days

Life-span 15 years 15 years 15 years 15 years

Date of installation 2016 2016 2016 2016

Engine fuel consumption 173g/kW-hr 173g/kW-hr 173g/kW-hr 173g/kW-hr

Urea rate 10%SFC 10%SFC 10%SFC 10%SFC

Urea storage for continuous operation 45 tons 13 tons 5 tons 21 tons

Total urea consumption per year 969 tons 1130 tons 1211 tons 448 tons

Urea cost per ton 390 USD 390 USD 390 USD 390 USD

300 € 300 € 300 € 300 €

Periodical maintenance after every 1,000 hours 1,000 hours 1,000 hours 1,000 hours

Working hour needed for maintenance 6 hours 6 hours 6 hours 6 hours

Cost of maintenance 150 €/hr 150 €/hr 150 €/hr 150 €/hr

SCR weight (including catalyst blocks) 32 tons 14 tons 10 tons 9 tons

SCR service volume 175 m3 70 m

3 50 m

3 41 m

3

Total weight loss 77 tons 27 tons 15 tons 30 tons

SCR Capital cost 1,814,400 € 806,400 € 662,400 € 552,000 €

O&M cost (Year 1) 292,374 € 343,502 € 369,517 € 363,217 €

O&M cost (Sum of 15 year) 3,517,370 € 4,132,471 € 4,445,436 € 4,369,644 €

Net Present Cost (NPC) 5,331,770 € 4,938,871 € 5,107,836 € 4,921,644 €

The capital cost is relatively lower than any of the scrubber systems. However the annual urea

consumption can cost up to 66% of the CapEx depending on the operational profile. The

weight and space taken by SCR systems are much less than the scrubber systems that it will

have very small impact to the stability and cargo loss.