WIND ASSISTED PROPULSION SYSTEM FOR FUEL SAVING ...

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WIND ASSISTED PROPULSION SYSTEM FOR FUEL SAVING

HAMRAN BIN HARUN

This dissertation is submitted

in fulfillment of the requirement for the

Master Degree of Mechanical Engineering

(Marine Technology)

Faculty of Mechanical Engineering

University of Technology Malaysia

DECEMBER 2011

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Dedicated to my family, and my friends

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ACKNOWLEDGEMENT

I would like to express my sincere appreciation to my supervisor, Prof. Dr. Abd.

Saman Abd. Kader and Assoc. Prof. Dr. Omar B. Yaakob for his precious continuous

guidance, support and encouragement throughout my study. His ideas, suggestions and

comments have given me the courage to handle this study and formed a valuable part of

this study.

I would also like to express my gratitude to those who have contributed to this study

especially beloved family for valuable support throughout this study.

Finally, I would like to thank all supervisor and friends, who involved directly

and indirectly in the accomplishment of this study.

Thank you.

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ABSTRACT

Increasing fuel prices and strong environmental concerns have changed the

landscape for the shipping industries. The changing, competitive environment has

rekindled an interest in improving ship efficiency and performance sustainability. As

MISC Berhad has a vision to become a world class player in the shipping industry,

alternative ways have to be discovered for ensuring a competitive edge in the shipping

business. Wind assisted ships are to be considered as an alternative way to reduce fuel

consumption and damage to the environment. The aim of this study is to develop a wind

assisted propulsion system and to assess its techno economic feasibility on a specific

vessel and a selected route. Chemical carrier tankers from the MT Bunga Melati series

were chosen and the routes selected were between the Middle East, Singapore and the Far

East. For this study, actual data collected was for a period of more than two years. This

data was taken from the daily noon reports of the ship master which are reports to his

company on a daily basis during a ship’s voyage. The data consists of the main ship

operational parameters as well as the wind speed and directions. A kite was designed and

the propulsive forces developed in the voyages throughout the year were estimated.

Finally, the economic assessment was carried out using payback period and Net Present

Value criteria. The calculations showed a payback period of 10 years while Net Present

Value was strongly positive indicating a profitable investment. The effect of using the

kite on CO2 emission was determined using Energy Efficiency Design Index (EEDI) and

Energy Efficiency Operational Indicator (EEOI) developed by the International Maritime

Organisation. Both indicators showed a positive reduction, indicating that the use of the

kite is not only profitable economically but also improves the ship CO2 reduction

performance.

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ABSTRAK

Peningkatan harga minyak dan kesedaran terhadap masalah pencemaran alam

sekitar disebabkan penggunanaan bahan bakar telah menukarkan lanskap industri

perkapalan. Perkembangan pesat industri perkapalan telah menarik minat bagi

meningkatkan kecekapan prestasi perkapalan untuk terus berdaya saing. Seperti visi

MISC Berhad untuk menjadi peneraju utama dunia di dalam industri perkapalan,

alternatif lain perlu dicari untuk memastikan MISC Berhad sentiasa berdaya saing dalam

perniagaan perkapalan. Kuasa pergerakan dengan bantuan angin perlu diberi perhatian

sebagai alternatif dalam mengurangkan kebergantungan terhadap penggunaan minyak

dan dapat mengurangkan pencemaran terhadap alam sekitar. Fokus kajian ini adalah

untuk membangunkan sistem propulsi bantuan kuasa angin dan untuk menganggarkan

kesesuaian dari segi tekno ekonomi pada kapal dan laluan tertentu. Laluan siri MT Bunga

Melati, iaitu kapal pengangkut bahan kimia adalah diantara Timur Tengah, Singapura dan

Timur Jauh telah dipilih untuk kajian ini. Data harian sebenar untuk tempoh lebih dua

tahun yang dilaporkan oleh kapten kapal semasa kapal belayar kepada syarikat akan

digunakan untuk kajian ini. Data tersebut mengandungi parameter utama operasi kapal

seperti kelajuan dan arah angin. Layar layang-layang dicipta dan daya propulsi semasa

pelayaran sepanjang tahun telah dianggarkan. Akhir sekali, penilaian ekonomi dengan

menggunakan kaedah “Payback” dan “Net Present Value”. Berdasarkan pengiraan

menunjukkan tempoh “Payback” ialah selama 10 tahun, manakala kaedah “Net Present

Value” menunjukkan nilai positif pada keuntungan pelaburan. Kesan pengunaan layar

layang-layang terhadap CO2 akan ditentukan mengunakan “ Energy Efficiency Design

Index (EEDI)” dan “Energy Efficiency Operational Index (EEOI) yang disarankan oleh

“International Maritime Organisation”. Kedua-dua indek menunjukkan pengurangan

yang positif, ini menunjukkan pengunaan layar layang-layang bukan sahaja baik dari segi

ekonomi tetapi juga dalam mengurangkan penghasilan CO2.

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CONTENTS

CHAPTER TOPIC PAGE

TITLE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

CONTENTS vii

LIST OF FIGURES xi

LIST OF TABLES xiii

LIST OF APPENDICES xiv

SYMBOLS AND ABBREVIATION xv

CHAPTER 1 INTRODUCTION

1.1 Background 1

1.2 Statement of Problem 2

1.3 Objective 3

1.4 Scope 3

1.5 Outline of Thesis 3

CHAPTER 2 LITERATURE REVIEW

2.1 Fuel Saving and Emissions 5

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2.2 Wind Assisted Ship 6

2.2.1 Flettner Rotor 7

2.2.2 Aerofoil (Wing sail) 8

2.2.3 Kites 10

2.2.4 Soft Sail 11

2.2.5 Wind Turbine 13

2.3 Selection of Wind Assisted Propulsion System 14

2.4 Reducing Air Pollution From Ship 16

2.5 The Use of Kite for Wind Assisted Ship 18

2.6 Investment Appraisal 22

2.6.1 Methods of Investment Appraisal 22

2.6.1.1 Payback 22

2.6.1.2 Annual or Average rate of Return (ARR) 23

2.6.1.3 Net Present Value (NPV)

or Discounted Cash Flow 24

2.6.1.4 Internal Rate of Return (IRR) 25

2.7 Energy Efficiency Design Index (EEDI) 26

2.8 Energy Efficiency Operational Index (EEOI) 27

CHAPTER 3 METHODOLOGY

3.1 Overview 28

3.2 Selection of Ship 30

3.2.1 Ship Particular 30

3.3 Route of Study 31

3.3.1 Weather in Route 31

3.3.1.1 South Asian Monsoon 31

3.3.1.2 East Asian Monsoon 32

3.3.2 Wind Condition 32

3.4 Cost Estimation 34

3.5 Investment Appraisal Technique 33

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3.6 CO2 and Energy Efficiency Design Index (EEDI)

Calculation 35

3.7 Energy Efficiency Operational Index (EEOI) Calculation 35

CHAPTER 4 THEORY

4.1 Sail Theory 36

4.1.1 Basis Concept of Sailing 36

4.2 Airfoil Concept 43

4.3 Definitions of Lift and Drag 44

4.3.1 Lift Force 45

4.3.2 Drag Force 46

4.4 Force analysis on Kite 47

4.4.1 True and Apparent Wind 49

4.4.2 Wind Speed 50

4.5 Propulsion Force 51

4.6 Kite Dimension 51

4.6.1 Angle of Attack 52

4.7 Control System and Routing 53

4.8 Ship Resistance 55

4.9 Propulsion Estimation 56

CHAPTER 5 RESULTS AND DISCUSSION

5.1 Route Analysis 59

5.1.1 Route Result 61

5.2 Wind Result 67

5.3 Propulsion Result 69

5.3.1 Relationship between angle of attack with CL/ CD 70

5.3.2 Propulsion force generated at selected route 71

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5.4 Case Study 75

5.5 Case Study Result 76

5.5.1 Fuel Savings 78

5.5.2 CO2 Savings 78

5.5.3 Calculated Value Attained for Energy Efficiency Design

Index (EEDI) 79

5.5.4 Calculated Energy Efficiency Operational Index

(EEOI) 81

5.6 Investment Appraisal Results 83

4.4.1 Payback Method 83

4.4.2 Net Present Value (NPV) Method 85

5.7 Discussion 86

CHAPTER 6 CONCLUSIONS AND RECOMMENDATION

6.1 Conclusions 89

6.2 Recommendation 90

REFERENCES 92

APPENDICES

Appendix A Example of Fuel Oil Monitoring System

Appendix B Ship Power Curve

Appendix C Route Analysis

Appendix D Propulsion Result

Appendix E Case Study

Appendix G Ship Particular

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LIST OF FIGURES

NO OF FIGURE TITLE PAGE

2.1 Artist impression of the E ship from Enercon 8

2.2 Type of wing sail vessel 9

2.3 Skysails Kite System 10

2.4 General plans “Dynaship” 12

2.5 Sail-assisted tanker “Shin-Aitoku-Maru” 12

2.6 Sail-equipped fishing boar “Enoshima-Maru” 13

2.7 Wind turbine 14

2.8 Relative fuel saving, 350 meter line 15

2.9 Oil prices from year 1999 to 2008 17

2.10 Power diagram wind 18

2.11 Direction of wind 21

3.1 Methodology flow chart 29

3.2 Sample of ship daily Noon Report 33

4.1 Combination between lift and drag 38

4.2 Lift and Drag relationship 39

4.3 Force on sail 40

4.4 Forces of water acting on a centreboard 41

4.5 Force acting on a sail 41

4.6 Drift of a boat 42

4.7 Three forms of wind 43

4.8 NACA airfoil geometrical construction 44

4.9 Aerodynamic forces 45

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4.10 Free body diagram of kite 49

4.11 True wind and apparent wind 50

4.12 Propulsion force acting on the ship 51

4.13 Cross section of the kite 52

4.14 Variation of �� ratio with Angle of Attack 53

4.15 Control system of the skysail technology 54

4.16 Ship resistance curve 55

4.17 Overview of process to determine Propulsion Force 57

4.18 Overview of process to determine power saving 58

5.1 Route from Singapore to Middle East – 3 sector 60

5.2 Route from Singapore to Taichung (Far East)

– 2 sector 60

5.3 Wind Speed on Monthly Average

(Singapore to Jeddah) 63


(Jeddah to Singapore) 64


(Singapore to Taichung) 65


(Taichung to Singapore) 66

5.7 Wind speed based on months for sector 1

(Singapore to Jeddah route) 68

5.8 Relationship between angle of attack with �� 70

5.9 Propulsion force distribution

(Singapore to Jeddah route) 71


(Jeddah to Singapore route) 72


(Singapore to Taichung route) 73


(Taichung to Singapore route) 74

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5.13 CO2 Savings versus Years 79

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LIST OF TABLE

NO OF TABLE TITLE PAGE

2.1 Proposed EEDI reduction schedule 26

3.1 Ship particulars of the MT Bunga Melati series 31

5.1 Route sectors 62

5.2 Ship data converted to wind speed using the

Beaufort scale 62

5.3 Wind direction based on ship heading 69

5.4 Case Study- Voyage Days 75

5.5 Case study- Trade Pattern 76

5.6 Summary of fuel savings 77

5.7 Summary of Case Study 78

5.8 Main Engine data for calculate EEDI 80

5.9 Auxiliary Engine data for calculate EEDI 80

5.10 Innovative energy data for calculate EEDI 81

5.11 EEOI (without kite) 82

5.12 EEOI (with kite) 82

5.13 Summary of detail cost 83

5.14 Simple Payback Method 84

5.15 Discounted Payback Method 84

5.16 Operational NPV 86

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LIST OF APPENDICES

NO OF APPENDIX TITLE

Appendix A Example of Fuel Oil Monitoring System

Appendix B Ship Power Curve

Appendix C Route Analysis

Appendix D Propulsion Result

Appendix E Case Study

Appendix G Ship Particular

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SYMBOLS AND ABBREVIATION

A area of kite

AR Area ratio

CD drag coefficient

CL lift coefficient

d diameter

F Force

D Drag Force

L Lift Force

VT True wind speed

VA Apparent wind speed

Vs Ship Speed

l Length

P Pressure

LOA Length of overall

LBP Length between perpendiculars

W Weight

t Time

V Velocity

Re Reynolds Number

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� Specific density (of air)

VA Apparent wind speed

VT True wind speed

VS Vessel speed

� Apparent wind angle

� True wind angle

W(z) Wind speed at altitude z above (sea) surface

uref Wind speed at reference level

zref Reference level (10m)

z0 Surface roughness (depending on wave height)

RT Total resistance

PE Effective power

PD Delivered power

PB Brake power

�P Propeller efficiency

�O Open water test propeller efficiency

�s Shaft efficiency

FP Propulsive force

q Dynamic pressure

n Number of years

Rn Net cash flow

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e Yearly cost increment

i Discount rate

CF Non-dimensional conversion factor between fuel

consumption measured in g and CO2 emission also

measured in g based on carbon content. The subscripts MEi

and AEi refer to the main and auxiliary engine(s)

respectively.

Vref Ship speed, measured in nautical miles per hour (knot), on

deep water in the maximum design load condition.

Capacity Deadweight for dry cargo carriers, tankers, gas tankers,

Containerships, RoRo cargo and general cargo ships, gross

tonnage for passenger ships and RoRo passenger ships, and

65% of deadweight for container ships.

Deadweight Means the difference in tonnes between the displacement of

a ship in water of relative density of 1,025 kg/m3 at the

deepest operational draught and the lightweight of the ship.

P Power of the main and auxiliary engines, measured in kW.

The subscripts ME and AE refer to the main and auxiliary

engine(s), respectively.

SFC Certified specific fuel consumption, measured in g/kWh, of

the engines.

fj Correction factor to account for ship specific design

elements.

Fw Non-dimensional coefficient indicating the decrease of

speed in representative sea conditions of wave height, wave

frequency and wind speed.

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feff(i) Availability factor of each innovative energy efficiency

technology.

FC (Fuel consumption) is all fuel consumed for the period in

question

�� CO2 emission per tonne of fuel calculated from the

carbon content of the fuel used (e.g. HFO)

�� Mass of transported cargo in metric tonnes

D (distance sailed) is the actual distance sailed in nautical

miles

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CHAPTER 1

INTRODUCTION

1.1 Background

Increasing fuel prices and strong environmental concerns have changed the

competitive landscape of the shipping industry today. This present environment has

rekindled an interest in improving efficiency and sustainability in the performance of

ships. To meet with the changing commercial markets and the economic environment,

there is the requirement for new vessel designs with more flexibility, longer lifespan,

and with more energy efficient operating systems which will be highly cost effective.

The need to minimize operating costs is paramount in order to be competitive.

The current oil fuel based energy source, at recent high prices, can result in fuel costs as

high as 50 percent of the operating costs [1]. Alternative energy sources for power

generation such as LNG, fuel cells, nuclear, wind assisted ships are now being

considered by many shipping companies. Apart from the hull and propulsion efficiency,

optimization of ship running costs and quality of services depend on the performance of

the operational systems and processes such as voyage management, loading and

maintenance.

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As the MISC vision is to become a world class player in the shipping industry,

alternative ways have to be discovered for ensuring a competitive edge in the shipping

business. Such development procedures are illustrated in Appendix A. These

procedures range from fuel oil consumption monitoring, voyage management and

propeller polishing for increasing fuel efficiency and to reducing fuel consumption [10].

However there is no alternative study that has been done within the MISC group for

reducing dependence on fossil fuel. Wind assisted shipping is to be considered as an

alternative way to reduce fuel consumption and prevent further damage to the

environment. Earlier studies have shown that with the current wind assisted system

technology, annual savings of between 10 to 30 percent of fuel consumption can be

expected [31].

This study will focus on the feasibility of a wind assisted system to be applied

onboard a MISC ship. The wind assisted systems generate thrust from the wind and

thereby reduce dependence on fossil fuel and main engine operation.

1.2 Statement of Problem

Maritime Shipping is nearly dependent on fuel oil. In the last 10 years, crude oil

prices rose annually by 10 percent on the average and in 2009, a high upward

movement has been observed. This development, places tremendous financial pressure

on the shipping industry as the fuel oil cost accounts for more than half of a ship’s

operating cost. The International Energy Agency (IEA) has projected an average oil

price of USD 200 per barrel by 2013. According to the IEA report the main reason for

this price increase is the continuing decline in oil production rates by about 6-7 percent

annually and faces a growing demand of 1 percent per year. Soon, shipping companies

will be forced to reduce their sulfur emissions which are already damaging the

environment at present. The maritime industry is responsible for almost 4 percent of the

worldwide CO2 emission. The only way to reduce the emission is by reducing the

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burning of fuel. The way out of this crisis is by opening up alternative energy sources

for the ships and this makes the use of free wind power more attractive.

1.3 Objective

The objective of this study is to develop a wind assisted propulsion system and to

assess its techno economic feasibility.

1.4 Scope

The scope of this study covers the wind assisted propulsion system, the route

and ship selection, the collection and compilation of wind data from noon reports,

analyses of wind data of chosen routes, the development of wind assisted propulsion

system, the calculation of power generated by wind and expected fuel savings, the

assessment of techno economics with the application of the wind assisted propulsion

system and finally the recommendations for further research work.

1.5 Outline of Thesis

This thesis comprises five chapters. Chapter one will cover the introduction and

background of the study, the objective to study the wind assisted propulsion system and

lastly the scope of the study. Chapter two covers the literature reviewed. There are three

main parts in this chapter. Part one discusses the contribution of the wind assisted

propulsion system to fuel saving and the effect of releasing CO2 into the atmosphere by

the shipping industry. The second part, discusses the previous study conducted for the

wind assisted propulsion system and the application and advantages of the wind

assisted propulsion system. In the third part, the kite sail theory and its application on

the vessel are discussed. Chapter three covers the methodology and selection of the

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vessels, the routes of study, method on actual data collection from the vessel, kite

dimensions, cost estimation, a case study of a ship and lastly an investment appraisal

will be determined. Chapter four contains the main discussion on the route analysis and

the wind analysis for the launching of kites. This chapter also discusses the propulsion

force derived by applying a kite on the vessel. By generating a case study, the total fuel

savings on a chosen route can be determined as well as the emission of CO2 can be

reduced and furthermore an investment appraisal will be also discussed. Finally, in

Chapter five, the conclusion on the objective of the study will be explained in brief and

recommendations and suggestions for the improvement of the study or future research

will be provided.

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CHAPTER 2

LITERATURE REVIEW

2.1 Fuel Savings and Emissions

Maritime shipping is entirely dependent on oil and the increase in price lately

has placed a tremendous pressure on costs in this industry. In 2009, the cost of marine

fuel was from 500 to 1200 USD or more per ton depending on the grade and quality

which appeared to be an inconceivable price just a few years ago. There seems to be no

end to this trend and the respected investment bank of Goldman Sachs deems an

increase of 200 USD in the price of oil of a barrel to be possible in the near future [4].

Cargo shipping is one of the most efficient mode of transportation in the world

but however it is now considered to be one of the causes for emitting climate-damaging

emissions and as such contributes significantly to the pollution of our environment. The

shipping industry carries 90 percent of the world wide freight and is contributing to

approximately 4 percent of the global CO2 emissions [5]. The International Maritime

Organization (IMO) has been urged by the European Commission (EC) to take action

to reduce its emissions into the air. CO2 is efficient in terms of g CO2 per ton-mile and

the shipping industry is less efficient in controlling Sulfur and Nitrogen Oxides (SOx,

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NOx), as the largest part of Sulfur and Nitrogen contamination in the coastal areas is

not due to land based industries but to the shipping industry[5].

The fuel burned by the shipping industry is a low residue of oil called heavy

fuel oil, releasing 3 tons of CO2 into the air for 1 ton of fuel burned, and a Sulfur

content limited to 1 percent of the fuel mass [5]. While the CO2 pollution from a ship is

directly linked to the amount of fuel burned, the Nitrogen pollution depends on the fuel

quality and how it is burned and factors such as temperature and the duration of the

combustion in the engine have to be considered. The shipping industry was excluded

from the United Nations Kyoto Protocol to slowdown climate change, but may well be

included in the successor to Kyoto, post 2012. Consequently the environmental impact

of shipping, until recently considered low, will gain importance as it is not considered

low any longer.

The shipping industry is now forced to improve its public image and comply

with the emission to air quotas being set in place locally for example in Scandinavia

and on the coastal areas of North America and soon will be designated as CO2 emission

trading scheme globally. The most efficient way for that is to reduce fuel consumption

in the shipping industry and thereby creating the opportunity to reduce its running costs

as well as to avoid being taxed highly for emissions that cause air pollution. The only

way out of the subjection to the oil prices is to open up alternative energy sources for

ships and this therefore makes the use of wind power more attractive.

2.2 Wind Assisted Ship

Shipping companies seeking immediate answers to soaring fuel prices are

simply slowing down. Higher fuel costs and the mounting pressure to curb emissions

are leading some parties in the shipping industry to investigate the use of wind power

which has the capability to assist both the objectives.

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The idea of turning wind into a propulsive force to assist the propulsion of ships

has sailed a long way from the masted clippers in the middle of the 19th century to the

early 21st century unmasted, automated, remote controlled kites pulled ships [4].

There are five major types of wind assisted approaches and these are the

Flettner rotor, the wing sail, the kite sail, the soft sail and the wind turbine but however

only the first three of them are favoured ( Flettner rotors, the wing sails and the kite

sails). Of these, the first two are fitted on the ship while the latter is tethered to it. These

approaches are described briefly in the following sections.

2.2.1 The Flettner Rotor

Spinning vertical rotors installed on the deck of a ship can convert wind power

into a thrust perpendicularly to the direction of the wind. This effect is known as the

Magnus Effect. The effect causes the side wind to be converted to the forward thrust

and thus propelling the vessel forward. Anton Flettner first successfully demonstrated

the rotor’s capability in1924 when he had an experimental vessel built and equipped it

with two large cylinder rotors at the Germania Shipyards in Kiel. These rotors are now

known as Flettner Rotors [5] but however the price of fuel at that time was so low that

there was insufficient interest in pursuing the use of wind power any further.

The current price of fuel and the increasing interest in global sustainable

development together with the need for environmental improvements has generated

considerable interest in the use of the Flettner Rotors to reduce fuel consumption and

associated CO2 emission. ENERCON GmbH, a German company which is one of the

world’s leading manufacturers of wind turbines and which has already installed more

than 13,000 wind turbines in over 30 countries, is having an energy efficient ship built

to carry its products to all its global customer based [5]. A large portion of the energy

required to propel the ship will be supplied by four Flettner rotors which are 25m high

with a width of 4m in diameter shows in Figure 2.1.

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Figure: 2.1 Artist impression of the E ship from Enercon. [6]

2.2.2 Aerofoil (wing sail)

Figure 2.2 shows a prototype commercial 50,000 ton product carrier using a

wing sail system developed as a result of a project funded by the Danish Ministry of

Environment and Energy in 1995. A UK company, Shadotec plc, is involved in

developing the wing sail in conjunction with a Norwegian marine consultancy and a

Norwegian shipping company with the objective of investigating the wing sail

propulsion for commercial ships. This project is funded by the Norwegian National

Research Council [6]. The complete system will consist essentially of one or more

computer controlled wing sail thrust units mounted on a vessel. Initial design

considerations indicate that fuel saving and emission reduction of greater than five

percent can be expected from the prototype system on a research vessel.

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Figure 2.2 Type of wing sail vessel, [6]

The following are some major disadvantages of the wing sail.

• In unfavourable winds, large masts create a lot of drag and could cause ships to

heel and sometimes rather dangerously.

• Masts and their pivoting sails take up valuable container space on the deck.

• Loading and unloading is more expensive, since the cranes that lift containers

must work around the masts.

• The cost of retrofitting a cargo ship with a row of masts, and strengthening its

hull and deck to dissipate the additional stress, could take several years to

recoup in terms of fuel saved.

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2.2.3 Kites

Kites have some major advantages and these are that they:

• Can be added to existing ships

• Take up no deck space

• Require minimal retro-fitting

• Can be taken in out of the weather when not in use

• Can be taken off the boat for maintenance

• The capital cost of the sail system is likely to be much less than a wing sail

system and can be recouped in significantly less time and can be very cost

effective when retrofitted

The two companies involved in kite sails are Sky Sails, in Germany, and Kite Ship

in the United States. A typical configuration of a Sky Sails kite applied to a cargo ship

is shows in Figure 2.3.

Figure 2.3: Sky Sails Kite System [7]

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The kite system, which has been developed over 10 years with assistance from

the German government, uses an automatic pilot, is controlled by computers and runs

on a metal track around the ship. This allows the sail to move around to collect wind

and to also prevent tilting [7].

2.2.4 Soft Sail

This device is the most popular and has been used for the classic tall ships. In

1955, the project of Dynaship in Germany began to develop the semi-rigid squire sail as

shows in Figure.2.4. This sail however, was not realized at all, but this concept maybe

succeeded by JAMDA’s rigid sail [8]. As for the fore and aft sail, traditional gaff sail

has been well used for topsail schooners. Bermuda sail that is a more simplified loose-

foot sail is still used for a sailing yachts and dinghies. Wartsila Ab. developed the

automatic sail handling system and designed the modern sail cruising ships Wind Star,

Wind Song and Wind Sprit from 1986 to 1988 which is shows in Figure.2.5.

Furthermore, the larger sail-equipped cruising ship Club Med 1 and Club Med 2 were

constructed from 1990 to 1992[8].

Such simple sail is also applied to fishing boats in Japan. Aburatsubo Port

Service Co. developed the sail system, and many sail-assisted fishing boats were

constructed around 1985. Figure.2.6 shows the example of this sail.

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Figure 2.4 General plans “Dynaship” [8]

Figure 2.5 Sail-assisted tankers “Shin-Aitoku-Maru” [8]

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Figure 2.6 Sail-equipped fishing boars “Enoshima-Maru” [8]

2.2.5 Wind Turbine

Wind turbines and wind mills have been known for generating clean energy for

decades. Ships in the Nile first utilized wind power over 5000 years ago. The Persians

later employed wind power to mill grain and the Europeans after that in the seventeenth

and eighteenth centuries went on to develop wind power further for pumping water.

Therefore the idea of harnessing wind energy and converting it to mechanical energy is

relatively an old idea but however the installation of windmills is very much a later idea.

The first windmill to generate electricity in the U.S. was installed in 1890. In 1979 the

first grid connecting a turbine with a capacity of 2 MW was installed in Boone, NC and

in 1988 another grid connecting a turbine was constructed in Orkney, Scotland [4].

Wind turbine can propel a vessel in all directions to the wind including directly

towards the windward. Wind turbine rotors can also be operated in a freely rotating

auto gyro mode but at lower lift to drag ratios compared with soft and rigid sails. Net

thrust can be very high at a low ship speed. Wind turbines are shows in Figure 2.7.

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Figure 2.7: Wind turbine [9]

2.3. Selection of Wind Assisted Propulsion System

Based on the paper from Peter Naaijen [2], a study on application of 500m2 kite

to a 500 deadweight tanker which powered by 12000kw diesel engine has been carried

out. The ship tanker was chosen due to low speed about 15.5 knots and this will

introduce more benefit from the wind propulsion as the wind direction will be relatively

more from the stern. The model experiment has been carried out by Journee [3] at the

Delft University Ship Hydromechanics Laboratory with a model of ship particular

providing all the necessary hydromechanics data on the hull to perform the

performance prediction calculation. For the cross sectional shape of the kite a similar

airfoil shape was used as is often applied for kite surfing which is a NACA 4415. The

towing line of 350 meter length was adopted having an elliptical cord length

15

distribution over span. The result of case study is presented as a polar diagram of

relative fuel saving in Figure 2.8.

Figure 2.8 Relative fuel saving, 350 meter line

The angular axis represents the true wind from the bow. The radial axis

represents the true wind direction from the origin represent the fuel consumption as a

percentage of the fuel consumption as it would be without using the kite. The different

lines represent different wind speed as indicated in the legend. For upwind conditions,

the kite cannot operate as the wind direction is simply leaves no accessible area where

the kite is able to fly a prescribed orbit resulting in a propulsion force. From the graph,

the fuel saving rapidly increases with wind speed. For a wind speed of Beaufort 6 the

fuel saving amount to up 32% while for Beaufort 7 savings of 50% are achieved.

16

Based on above study and literature, the kite has been selected to this study due

to high cost saving compare to other wind assisted propulsion system.

2.4 Reducing Air Pollution from Ships

Wind energy has historically been used directly to propel sailing ships or been

converted into mechanical energy for pumping water or grinding grain, but the

principal application of wind power today is for generating electricity. Wind energy as

a power source is favored by many environmentalists as an alternative to fossil fuels, as

it is plentiful, renewable, widely distributed, clean; and emits less greenhouse gases.

Ships are the most energy efficient means of transportation but nevertheless, the

world’s shipping industry is responsible for some 4 percent of the global emissions caused

by human activities with the trend heading upwards. The International Maritime

Organization (IMO), the United Nations regulatory body for shipping on an international

level, has now responded to this development and new rules take force starting in 2010

that are designed to gradually reduce hazardous ship borne emissions of sulfur and

nitrogen oxides by the year 2020 [10].

The ceiling for the sulfur content of ship emissions w i l l be lowered from the

present 4.5 percent to 0.5 percent. A cap of 0.1 percent will apply starting in 2015 for

what are called Sulfur Emission Control Areas, or SECAs, which include the North Sea

and the Baltic Sea. The limits for nitrogen-oxide (NOx) emissions for ship engines

having a power output of 2,000 kW o r more w i l l start dropping from 9.8 grams of NOx

in 2010 to 2.0 grams in 2016 and a slightly higher limit will apply for smaller ship engines

[10].

Since f o s s i l energy resources on our planet are limited, the prices of these

resources are rising continuously and therefore high oil prices will considerably increase a

17

ship's operating cost. At present fuel costs are already amounting to more than half of the

operating cost of a ship. Increasing efficiency using ship diesel has almost reached i ts

maximum potential and has been found to be extremely expensive. According to the

calculation of an expert on ship propulsions, shipping companies would have to invest up

to 500,000 Euros in order to reduce a ship’s fuel consumption by 1 percent. The high price

of fuel in recent years and the prospect of even higher real prices in the long term have

led to focusing on substituting by using alternative fuel such as wind assisted

propulsion. Oil price movement for period 10 years from 1999 to 2008 showing in

Figure 2.9

Figure 2.9 Oil prices from year 1999 to 2008. [28]

Wind assisted propulsion would offer the possibility of substituted wind energy

for fuel derived energy in the speed range of a vessel. It may be possible to reduce the

18

cost of fuel and reduce emission without compromising with the speed required by the

vessel for trading purposes and can also be an alternative power for the main engine.

2.5 The Use of Kite for Wind Assisted Ship

One of the big advantages of kites over conventional rigs, rotating cylinders,

and wind turbines is the relative freedom from the heeling momentum. This will allow

the attaching of kites to most commercial ships without any significant modifications.

Another advantage is the dynamic sheeting, or the ability to fly patterns in the sky to

maintain relative winds at the kite that are several times stronger than the wind on the

deck.

Figure 2.10, shows the power extracted by various sail types at various course

angles. This was originally published by Lloyd Bergessen in support of the design of

Mini Lace in 1981, then adapted for kites by Schmidt in 1985, and finally by Roeseler

in 1996 for more efficient kites [11].

Figure 2.10 Power diagram wind [11]

19

Wind is cheaper than oil and is the most economic and environmentally sound

source of energy on the high seas. And yet, shipping companies are not taking

advantage of this attractive potential savings at present for a simple reason which is,

‘So far no sail system has been able to meet the requirements of today's maritime

shipping industry.’ However SkySails, a company based in Hamburg, is offering a wind

propulsion system based on large towing kites, which have the potential to meet all

these requirements. Depending on the prevailing wind conditions, a ship’s average

annual fuel consumption and emissions can be reduced by 10 to 35 percent by using the

SkySails System. Under optimal wind conditions, fuel consumption has been lowered

by as much as 50 percent [3].

These figures are based on test results with ocean going vessels and current kite

sizes. As technology advances, relative kite sizes can be increased and fuel savings will

grow. Virtually all existing cargo vessels and new builds can be retrofitted or outfitted

with the auxiliary wind propulsion system. The kite system is used for the relief of the

main engine, which remains fully available if required. This dual propulsion solution

offers the flexibility required to minimize operating costs. Economical acquisition and

operating costs for the SkySails-System would lead to short amortization periods of

between 3 and 6 years, depending on the routes sailed [7]. The ship's regular crew is

adequate for operating the system and no additional personnel costs should arise.

The SkySails-System consists of three simple main components: A towing kite

with rope, a launch and a recovery system, and a control system for automatic operation.

Instead of a traditional sail fitted to a mast, SkySails uses large towing kites for the

propulsion of the ship. Their shape is comparable to that of a paraglide. The towing kite

is made of high-strength and weatherproof textiles. The tethered flying kite can operate

at altitudes between 100 and 300 m where stronger and more stable winds prevail [4].

By means of dynamic flight manoeuvres the system generates five times more power

per square meter sail area than the conventional sails.

20

Traction forces are transmitted to the ship via a highly tear-proof synthetic cable.

The launch and recovery system manages the deployment and lowering of the towing

kite and is installed on the forecastle. During a launch, a telescopic mast lifts the towing

kite, which is reefed like an accordion, from its storage compartment. At a sufficient

height the towing kite then unfurls to its full size and can be launched. A winch releases

the towing rope until operating altitude has been reached. The recovery process is

performed in the reverse order. The entire launch and recovery procedure is carried out

largely automatically and lasts approximately 10 to 20 minutes in each case. The ship’s

crew can operate the system from the bridge. Emergency actions can be initiated at the

push of a button.

The automatic control system performs the tasks of steering the towing kite and

adjusting its flight path. All information on the operation status of the system is

displayed in real-time on the monitor of the workstation and therefore is easily

accessible to the crew.

The kite system supplements the existing propulsion of a vessel and is used

offshore, outside the 3 mile zone and traffic separation areas. The system is designed

predominantly for operation in prevailing wind forces of 3 to 8 Beaufort at sea.

The system can be recovered, but not launched at wind forces below 3 Beaufort.

With regards to the classification of society regulations, the kite system is categorized

and treated as auxiliary propulsion. The operation of this system is not limited by any

regulations at present.

Their double wall profile gives the towing kites aerodynamic properties similar

to the wing of an aircraft. Thus, the system can operate not just to the downwind, but at

courses of up to 50° to the wind as well shows in Figure 2.11 [4]

21

Figure 2.11 Direction of wind [7]

The kite is easy to store when folded and requires very little space on board the

ship. A folded 160m² kites for example is of the size of a telephone booth. In contrast to

conventional sail propulsions the kite system requires no superstructures to obstruct

loading and unloading at harbours or navigating under bridges, since the towing kite is

recovered as soon as the 3 mile zone is reached. Unlike conventional forms of wind

propulsion, the heeling caused by the kite is minimal and virtually negligible in terms

of the ship safety and operation. Depending on the operator’s preferences, the main

engine can either be throttled back to save fuel, or kept running at constant power and

use the kite tow forces to increase the ship's speed.

22

Since this system is more reliable to the current commercial vessel, the wind

assisted kite will be the focus in this study on a selected MISC vessel with selected

routes.

2.6 Investment Appraisal

Investment appraisal techniques are methods of mathematically comparing

returns or predicted returns of different investment alternatives. These techniques allow

a range of different methods of comparison of investment alternatives, and each of

which can suit different types of businesses with differing objectives and problems. It

allows easy comparison between investment choices. Appraisal also examine all

aspects of proposed investments, the figures used in investment appraisal can only be

calculated by looking at costs of running the project, potential sales from the project,

and the likely selling price of goods produced must be determined.

2.6.1 Methods of Investment Appraisal

There are 4 methods of investment appraisal. They are:

• Payback

• Annual or average rate of return

• Net Present Value

• Internal Rate of Return

2.6.1.1 Payback

The payback method of investment appraisal is used to compare projects that

may be competing for a business's available investment capital. With the payback

23

method, the project that returns the initial cost of the investment first is chosen (19).

The payback method is especially useful if technology is changing rapidly or where

cash flow and liquidity is important.

Advantages of Payback method

• Simple to use.

• Assists with cash flow

• Effective when technology is fast changing

Disadvantages of Payback method

• Ignores flows of cash over the lifetime of the project.

• Ignores total profitability.

2.6.1.2 Annual or Average Rate of Return (ARR)

Using the ARR method of investment appraisal the project that has the highest

annual rate of return is chosen. Because of different costs of investments, different net

cash flows, different timing of flows, it is often difficult to decide between alternative

projects. The ARR method allows the calculation of a % rate of return for a project.

This allows easy comparison between competing projects, and a judgment can be made

whether a project is worthwhile (19). If for example the ARR figure for a project is

10%, this may be judged as too low, especially if the cost of borrowing, or returns from

investing cash are near to this figure.

Advantages of ARR method.

• Allows for all flows of cash.

• Easy to compare different projects.

24

• Allows comparison with costs of borrowing.

Disadvantages

• Does not allow for effects of inflation.

2.6.1.3 Net Present Value (NPV) or Discounted Cash Flow

NPV is a technique where cash inflows expected in future years are discounted

back to their present value. This is calculated by using the discount rate equivalent to

the interest that would have been received on the sums, had the inflows been saved, or

the interest that has to be paid by the firm on fund borrowed Using the discounted cash

flow method of investment appraisal the project that has the highest 'real return' is

chosen(20).

• If the NPV is positive, it means that the cash inflows from a project will yield a

return in excess of the cost of capital, and so the project should be undertaken if

the cost of capital is the organisation's target rate of return.

• If the NPV is negative, it means that the cash inflows from a project will yield a

return below the cost of capital, and so the project should not be undertaken if

the cost of capital is the organisation's target rate of return.

• If the NPV is exactly zero, the cash inflows from a project will yield a return

which is exactly the same as the cost of capital, and so if the cost of capital is

the organisation's target rate of return, the project will have a neutral impact on

shareholder wealth and therefore would not be worth undertaking because of the

inherent risks in any project.

Advantages of NPV method

25

• Allows for effects of inflation.

Disadvantages of NPV method

• Inflation is often unpredictable.

2.6.1.4 IRR - Internal Rate of Return

The IRR method of investment appraisal sets out to calculate what level of

discount of cash flows is required to make the Net Present Value of a project zero.

When this discount factor is calculated the firm is able to compare this figure with the

cost of borrowing to fund the project and therefore decide whether it is worthwhile

going ahead with the investment (20).

Advantages of IRR method

• Allows judgment of value of investment against a company’s standard level of

return interest rate.

• Allows for costs of borrowing, and opportunity cost.

Disadvantages of IRR method

• Can eliminate projects that may bring benefits other than financial ones.

26

2.7 Energy Efficiency Design Index (EEDI)

In attempting to regulate CO2 emissions from ships, the International Maritime

Organization (IMO) has introduced an index to ships called Energy Efficiency Design

Index (EEDI).

The Marine Environment Protection Committee, at its fifty-ninth session from

13 to 17 July 2009 has recognized the need to develop an energy efficiency design

index for new ships in order to stimulate innovation and technical development of all

elements influencing the energy efficiency of a ship from its design phase. EEDI is an

attempt to measure how much CO2 a ship emits per unit of transport provided. A

formula producing an EEDI for each ship is developed. The current EEDI formula is

outlined in MEPC.1/Circ.681, Interim Guidelines on the Method of the Calculation of

the Energy Efficiency Design Index for New Ships, and then an upper limit on EEDI is

mandated for all new buildings (21).

The attained new ship Energy Efficiency Design Index (EEDI) is a measure of

ships CO2 efficiency and calculated by the following formula (22):

(2.1)

IMO has yet to finalize the mandated decrease in EEDI; but the discussion has

focused on the reductions shows in Table 2.1.

Table 2.1 Proposed EEDI reduction schedule

Phase 1 Phase 2 Phase 3

2013 2018 2023

10 % 25% 35%

27

These reductions will be from a baseline that is determined by fitting a power

law regression to the existing fleet.

2.8 Energy Efficiency Operational Index (EEOI)

Besides EEDI, the International Maritime Organisation also issued interim

guidelines for voluntary ship CO2 emission indexing for use in trials. The formula for

this index, now called the Energy Efficiency Operational Index (EEOI), incorporated

the fuel consumption, distance sailed and cargo mass, along with the carbon content

and CO2 conversion factor for particular fuels, to calculate a “Carbon Dioxide

Transport Efficiency Index” which represents the ratio of mass of CO2 per unit of

transport work.

The Index proposed for trial is defined as the ratio of mass of CO2 per unit of

transport work and calculated using the following formula1:

EEOI = � ��

� �� (gram CO2 / tonne nautical mile) (2.11)

The fuel used on these ships was heavy fuel oil (HFO). Carbon content and

��values used in the calculating the index was those provided in MEPC Circular

684: 0.85 m/m and 3,114,400 g CO2 / t fuel respectively (23).

28

CHAPTER 3

RESEARCH METHODOLOGY

3.1 Overview

This study focuses on reducing the dependence on fuel consumption and cutting

operating costs to increase vessel efficiency. For this project, wind energy is selected as

an alternative energy or hybrid over heavy fuel oil which is commonly used in the

shipping industry.

Based on that, the study focuses on the type of energy generated by wind in order to

utilize this energy for operating commercial vessels. An MISC vessel from the MT

Bunga Melati Class Series is used to gather data for wind and route characteristics. The

actual wind data is gathered from the ship’s noon report which is submitted on daily

basis of the voyage by the Master to the owner of the vessel. Based on that data, the

wind and the ship’s course can be determined and analyses in order to assess the

feasibility of using a kite sail on a selected vessel on a specific route. Once all the data

has been analyzed, feasibility will be determined on the benefits of using the wind

energy on a selected vessel at a selected route based on cost savings which is mainly

contributed by the condition of the wind. An economic analysis will be carried out to

29

determine fuel and operating cost savings. The flow chart for this study is shown in

Figure 3.1.

Figure 3.1 Methodology Flow Chart

Literature review on wind assisted propulsion system

Selecting a wind assisted propulsion systems

Selecting a specific routes and vessels

Collecting of wind data of MISC ship

Analyzing data and conducting feasibility study

Designing of the kite wind assisted propulsion system

Determining the propulsion force and performing an economic study

Discussion on findings and results

Conclusions and recommendations

30

3.2 Selection of Ship

MISC has a very large fleet of commercial vessels. For this study, a chemical vessel

has been selected due to following reasons:

a) There are seven vessels in the same class

b) There are at least 3 vessels with the same trade route pattern which is from the

Middle East to the Far East

c) There is a long voyage for possible kite launching

The entire seven vessels have been built by Hyundai Heavy Industry (HHI) from

1994 to 2000. The ships were designed to meet the service speed of 14.5 knots with a

horse power of 8,640 at NCR and at propeller speed of 115.5 RPM. The vessel is also

fitted with a fixed pitch propeller with a diameter of 5,800mm. The main engine fuel oil

consumption is recorded at 25.7 tons per day. The accommodation is suited to house 37

crew members. Ship particulars and other details are provided in the Table below:

3.2.1 Ship Particulars

Table 3.1 Ship particulars of the MT Bunga Melati series.

Ship Particulars Dimensions

LOA 177.15 meters

LBP 168 meters

Breadth MLD 30 meters

Depth 15.5 meters

Design Draught 10 meters

Speed 14.5 knots

Propulsion Hyundai MAN B&W 6S50MC (MK6)

SFOC 124 g/psh

ME FOC 25.87 MT/day

NCR 8640 ps x 115.5 RPM

Detail of ship particular as per Appendix F.

31

3.3 Route of Study

This study will focus on routes between the Middle East and the Far East. Two

different routes will be considered in this study. The route between the Middle East, Jeddah

to Singapore which would take about two weeks approximately with vessel speed of 14.5

knots. The second route is between Singapore and the Far East, Ningbo, China which

would only take about a week with the same speed.

3.3.1 Weather in Route

Since the study is focused on wind energy, weather is the main component to

consider and wind behavior being the main detrimental factor to be studied on the

selected routes. Based on literature reviewed the routes selected are from the Middle

East to the Far East.

On route, the vessels pass through the Asian Monsoon regions and therefore are

exposed to the Monsoon winds that blow over these areas. This is a major wind system

that seasonally reverses its direction (e.g., one that blows for six months from the

northeast and six months from the southwest).The Asian monsoons may be classified

into a few sub-systems, such as the South Asian Monsoon which affects the Indian

subcontinent and surrounding regions, and the East Asian Monsoon which affects

southern China, Korea and parts of Japan (24).

3.3.1.1 South Asian Monsoon

The southwestern summer monsoons occur from June through September. The

Thar Desert and adjoining areas of the northern and central Indian subcontinent heats

up considerably during the hot summers, which causes a low pressure area over the

northern and central Indian subcontinent (24).

32

3.3.1.2 East Asian Monsoon

The East Asian monsoon affects large parts of Indo-China, Philippines, China,

Korea and Japan. It is characterized by a warm, rainy summer monsoon and a cold, dry

winter monsoon. The rain occurs in a concentrated belt that stretches east-west except

in East China where it is tilted east-northeast over Korea and Japan. The onset of the

summer monsoon is marked by a period of pre-monsoonal rain over South China and

Taiwan in early May. From May through August, the summer monsoon shifts through a

series of dry and rainy phases as the rain belt moves northward, beginning over

Indochina and the South China Sea in May, to the Yangtze River Basin and Japan in

June, and finally to North China and Korea in July. When the monsoon ends in August,

the rain belt moves back to South China (24).

3.3.2 Wind Condition

The wind behavior data will be collected and determined by using a noon report

sent daily by the captain of the ship to the owner or the company head office. The

document below shows an example of a daily noon report shows in Figure 3.2. Based

on the noon report collected, the wind direction over a vessel’s position can be plotted

and estimated. In order to get accurate wind data, several vessels that sail through the

same route are requested to also collect and analyze the data.

33

Figure 3.2 Sample of ship daily Noon Report

34

3.4 Cost Estimation

When a new sailing device is attached to a vessel, there definitely would be

some expenses to be accounted for. In this section, the discussion on costs includes

early investment and maintenance.

a) Investment cost

The investment cost is the cost involved to install sail devices. With reference the

latest literature reviewed on prices, the market price of a sail device which is about

390m2 is approximately USD 1 million. This estimated cost will be used for the

calculation for the cost analysis.

b) Installation Cost

Installation cost consists of strengthening the fundamental steel works, cabling and

the hydraulic system. The cost is estimated to be about 5 percent of the value of these

devices.

c) Maintenance cost

Maintenance for the sail normally depends on how frequently kites are launched

while the vessel is in operation. However for this study the estimated maintenance cost

will be about 7 percent of the price of the devices per year.

3.5 Investment Appraisal Technique

Payback method as a first screening process will be used for this study. If the

study able to get through the payback test, it ought then to evaluate with a more

sophisticated project appraisal technique. There are two type of payback method, which

is called simple payback method and discounted payback method. Simple payback

35

method is a measure of how long it will be before the investment make money, and

how long the financing term needs to be. For the discounted payback method the

discount rate will be used as below formula:

Discount rate factor = �

�� (3.1)

Net Present Value (NPV) is a technique where cash inflows expected in future

years are discounted back to their present value. The calculation by using a discount

rate equivalent to the interest that would have been received on the sums, had the

inflows been saved, or the interest that has to be paid by the firm on funds borrowed.

The NPV will be used for assess the effectiveness of the study in term of cash flow as

per below equation.

NPV = Rn [ [(1+e)/(1+i)]n-1]/(e-i) (3.2)

3.6 CO2 and Energy Efficiency Design Index (EEDI) Calculation

CO2 saving will be determined based on the fuel saving derived from the

propulsion generated by the kite. Based on literature review for every 1 ton of fuel

burned by the vessel it can release about 3 tons of CO2 into the air. From the fuel

saving also the Energy Efficiency Design Index (EEDI) can be determined using

formula given in equation 2.10. Detail of calculation and result will be discussed on

Chapter four.

3.7 Energy Efficiency Operational Index (EEOI) Calculation

EEOI calculation was carried out based on the formula given in Section 2.12.

A calculation has been carried out for ship with and without kite. A lower EEOI shows

better efficiency and lower CO2 emission during operation. Calculations will be carried

out for all sectors of the voyage.

36

CHAPTER 4

SAIL THEORY

4.1 Sail Theory

Sail theory is where the navigator uses to navigate the boat or vessel from one point

to another point. In this section the basis of sailing theory will be discussed in detail.

4.1.1 Basic Concept of Sailing

It seems obvious as to how a sailboat sails downwind; it is pushed along by the

wind in its sails but however it is less obvious how it can sail upwind or how some

sailboats can sail faster than the wind.

Sir Isaac Newton formulated three basic laws pertaining to the motions and

accelerations of all objects [12]. The third law says, “For any force exerted on an object,

an equal but opposite force must be exerted by the object onto whatever exerted the

force.” A direct consequence of this law is the conversion of momentum which means

that momentum equals mass times the velocity. The conversion of momentum tells us

37

that if the velocity of a certain object is somehow changed in either magnitude or

direction then the velocity of another object involved must also be changed accordingly.

Moreover, a large change in the velocity of a light object can be balanced by a small

change in the velocity of a massive object. This is, of course, how a sailboat sails.

Because of its large sail area, a sailboat can change the velocity that the sailboat imparts

to the air hitting her sails is mainly a change in the direction in which the air is moving.

So a sailboat can experience a large driving force even when she is sailing against the

wind. In the real world, there are two forces. One is the wind pushing on the sail when

it is changing direction. The air travelling over the leeward surface of the cambered sail

creates the second force. It has to travel a longer way to reach the end of the sail

termed as the leech, and as a consequence goes faster. This causes a pressure

differential in accordance with Bernoulli’s principle. More speed gives less pressure

and less speed gives more pressure. So a sailboat can sail upwind with the addition of

these two forces. However the force created by the depression is four times bigger than

the one created by pushing the air sideways.

A fluid flow exerts a force upon an object in a direction perpendicular to the

uninterrupted flow of that fluid. As a result, a lift is generated. But there is also the

creation of a drag that is force acting in the direction of the fluid. Because lift and

drag are defined as being perpendicular to one another, any force acting on a sail,

using trigonometry, can be divided into the lift and drag components [12] (refer to

Figure 4.1).

38

Figure 4.1, Combination between the lift and drag [11]

The relationship between the Angle of Attack and the lift coefficient is termed

as a lift curve and that between the Angle of Attack and the drag coefficient is the drag

curve. There is an Angle of Attack where the lift is maximum and an Angle of Attack

where the drag is maximum There is also an Angle of Attack where the ratio of lift to

drag is maximized. This L/Dmax represents the best upwind angle for a sailboat.

When the Angle of Attack increases, the lift also gradually increases until it

reaches its maximum value after which it falls sharply. At this same point, the drag

rises sharply. There is a sweet spot right before this point where the lift is almost

reaching the maximum level and the drag has not started to rise too sharply as yet. At

this point the ratio of the lift to the drag is maximized. This is the Angle of Attack

where one wants to try and put the sails up when sailing upwind. Before this point the

lift falls off and above this point the lift also falls off and the drag increases. Because

sails are made of cloth, when the lift is below a certain Angle of Attack, a sail will no

longer hold its shape or flap in the wind.

As a result, when sailing, one would want to keep the Angle of Attack

approximately between 15 to 20 degrees. This does not mean that one can sail within

39

15 degrees of the wind. There are two reasons for this; the angle of the wind on the sail,

where the Angle of Attack is not the same as the angle of the boat to the wind, and the

wind that the boat experiences is not the same as the true wind but is changed due to the

motion of the boat itself. This is called the “Apparent Wind”. This is the vector sum of

the true wind and the inverse of the boat’s speed. This means that the apparent wind

differs from the true wind in both heading and speed.

Figure 4.2 Lift and Drag[13]

In this diagram, the driving force on the boat is less than the lift created by the

sail when sailing upwind. There is also a large amount of heeling force generated by the

lift. When sailing upwind in strong winds, it is sometimes necessary to let the sail out to

achieve the best upwind boat speed [13].

40

Figure 4.3 Force on sail[13]

The large amount of sideways heeling is balanced by an equal but opposite

force on the centreboard of the sailboat. This is generated by the centreboard creating a

lift as it moves through the water at a certain small angle called the ship’s leeway and

pushes water sideways to leeward as it moves. The power of a sailboat comes from the

way in which the sail catches the wind. A sail is in fact a vertical wing and it operates

in the same way as a wing on a plane does. A sailboat uses its wing sail and the

centreboard which projects downward into the water to propel it forward. Figure 4.4

shows the forces that are acting on the centreboard. The flow of water around the

centreboard creates difference in the pressure [13].

41

Figure 4.4 Forces of water acting on a centreboard[14]

This pressure difference is the same as the pressure difference around the sail

where the high pressure is on the side towards the wind, and the low pressure on the

side away from the wind. By nature, high pressure moves towards a low pressure area

and as a result, it exerts a perpendicular force on the sail. This is shown in figure 4.5.

The forces on the centreboard together with the forces exerting on the sail provide

enough power to the sailboat to move forward.

Figure 4.5 Force acting on a sail[14]

The combination of the centreboard and sail results in a forward motion, but

there is some slipping. The term for this slipping is "drift". As shown in Figure 4.6, the

42

boat will not travel in the exact direction in which it is pointing. The drift will also be

influenced by other elements such as waves and currents. The stronger the waves and

the currents, the more drift the boat will experience. This is an important concept to be

aware of, in case of any lurking hazards nearby.

Figure 4.6 Drift of a boat [14]

The last aspect of the physics of sailing discusses is the concept of’ true’ and

‘apparent’ wind. These terms refer to the wind and its changes due to the wind direction

and the speed of the boat. True wind is defined as the direction of the wind to a

stationary observer. Induced wind is the wind experienced due to the movement of the

boat. A good analogy is riding a bike. When riding a bike on a day with no wind, the

rider still feels a wind. This wind is induced by riding the bike through the air. A boat

experiences wind in the same manner. The combination of these two winds is the actual

wind experienced by the boat. This wind is called the apparent wind. Figure 4.7

illustrates the three winds and how they relate to one another.

43

Figure 4.7 Three forms of wind

4.2 Airfoil Concept

The development of the National Advisory Committee for Aeronautics (NACA)

airfoil was started in 1929 with the systematic investigation of a family in airfoil

development for the Langley variable density tunnel [15]. Different types of airfoils

are commonly used these days.

The early NACA airfoil series, the 4 digit, 5 digit, and the modified 4 and 5

digits, were generated using analytical equations that describe the camber or curvature

of the mean line geometric centreline of the airfoil section as well as the section's

thickness distribution along the length of the airfoil. Later families, including the 6

Series, are with more complicated shapes derived by using theoretical rather than

geometrical methods. Before this, the NACA developed this series and the airfoil

design was rather arbitrary with nothing to guide the designer except past experience

with known shapes and experimentation with modifications to the shapes.

This methodology began to change in the early 1930s with the publishing of an

NACA report entitled “The Characteristics of 78 Related Airfoil Sections from Tests in

the Variable Density Wind Tunnel” [15]. In this landmark report, the authors pointed

out that there were many similarities between the airfoils that were most successful, and

44

the two primary variables that affect the shapes were the slope of the airfoil mean

camber line and the thickness distribution above and below this line. They then

presented a series of equations incorporating these two variables that could be used to

generate an entire family of related airfoil shapes. As airfoil design became more

sophisticated, the basic approach was modified to include additional variables, but the

two basic geometrical values remained as the core in all the NACA airfoil series, as

illustrated below.

Figure 4.8 NACA airfoil geometrical construction[15]

Airfoils of this family were designated by a number with four digits, such as

4415 Airfoil. All airfoils of this family had the same basic thickness distribution,

and the size and types of chamber were systematically varied to produce the family

related airfoils. The NACA airfoil sections have a higher maximum lift coefficient

and a lower minimum drag coefficient than those of the sections developed earlier.

For this study the NACA 4415-63 is chosen due to its high lift drag ratio.

4.3 Definitions of Lift and Drag

For a fluid in motion, the velocity will have different values at different

locations around the body. The local pressure is related to the local velocity, so the

pressure will also vary around the closed surface and a net force is produced. Summing

45

up or integrating the pressure perpendicular to the surface multiplied by the area around

the body produces a net force. Since the fluid is in motion, it can define a flow direction

along this movement. The component of the net force perpendicular to the flow

direction is called the lift and the component of the net force along the flow direction is

called the drag. In reality, there is a single net integrated force caused by the pressure

variations along a body. This aerodynamic force acts through the average location of

the pressure variation which is termed as the centre of the pressure.

Figure 4.9 Aerodynamic forces[16]

4.3.1 Lift Force

Lift is the force that directly opposes the weight of an airplane and holds the

airplane in the air. Lift is generated by every part of the airplane, but most of the lift on

a normal airliner is generated by the wings. Lift is a mechanical aerodynamic force

produced by the motion of the airplane through the air. Because lift is a force, it is also

a vector quantity, having both a magnitude and a direction associated with it. The lift

acts through the centre of the pressure of the object and is directly perpendicular to the

46

direction of the flow. There are several factors which affect the magnitude of lift. The

equation of the Lift Force is as described below:

Lift force, 2

2

1VSCL l ρ××= (4.1)

A lift occurs when a moving flow of gas is turned by a solid object. According

to Newton's Third Law of Action and Reaction the flow is turned in one direction while

the lift is generated in the opposite direction and because air is a gas and the molecules

are free to move about, any solid surface can deflect a flow.

The lift is a mechanical force which is generated by the interaction and contact

of a solid body with a fluid. It is not generated by a force field, in the sense of a

gravitational field, or an electromagnetic field, where a certain object can affect another

object without being in physical contact. For a lift to be generated, the solid body must

be in contact with the fluid; which means if there is no fluid, then there is no lift. For

example, a space shuttle does not stay in space because of the lift from its wings but

because of the orbital mechanics related to its speed. The space is nearly a vacuum and

therefore without air there is no lift generated by the wings.

A lift is generated by the difference in velocity between a solid object and a

fluid. There must be some motion between the object and the fluid and if there it is no

motion there will be no lift. It makes no difference whether the object moves through a

static fluid, or the fluid moves past a static solid object as the lift acts perpendicularly to

the motion while the drag acts in the direction that opposes the motion.

4.3.2 Drag Force

The amount of drag generated by an object depends on a number of factors,

including the density of the air, the velocity between the object and the air, the viscosity

and compressibility of the air, the size and shape of the body, and the body's inclination

to the flow. A drag equation can be described as follows:

47

Drag Force, D = .5 * Cd * r * V^2 * A (4.2)

In general, the dependence on body shape, inclination, air viscosity, and

compressibility is very complex. One way to deal with complex dependencies is to

characterize the dependence by a single variable. For drag, this variable is called the

drag coefficient, termed as Cd. During the time of the Wright brothers, the drag

coefficient was usually referred as the drag of a flat plate of an equal projected area.

For given air conditions, shape, and inclination of the object, one has to

determine a value for Cd in order to determine the drag. The drag coefficient is

composed of two parts; a basic drag coefficient which includes the effects of skin

friction and shape, and an additional drag coefficient related to the lift of the aircraft.

The additional source of drag is called the induced drag and it is produced at the tip of

the wing due to the aircraft lift. Because of pressure differences above and below the

wing, the air at the bottom of the wing is drawn onto the top near the wing tips and this

then creates a swirling flow which changes the effective angle of attack along the wing

and induces a drag on the wing.

4.4 Force analysis on Kite

Figure 3.10 depicts the forces acting on general kites. There are three principle

forces acting on the kite; the weight, the tension in the line, and the aerodynamic force.

The weight W always acts from the centre of gravity towards the centre of the earth.

The aerodynamic force is usually broken into two components, the lift L, which acts

perpendicularly to the wind, and the drag D, which acts in the direction of the wind.

The aerodynamic force acts through the centre of the pressure. Near the ground, the

wind may swirl and gust because of turbulence in the earth's boundary layer but once

away from the ground, the wind is fairly constant and parallel to the surface of the earth.

In this case, the lift is directly opposed to the weight of the kite, as shown in Figure

4.10. The tension in the line acts through the bridle point where the line is attached to

the kite’s bridle. If the tension is broken into two components, the vertical pull is

48

known as Pv, while the horizontal pull as PH. When the kite is in stable flight the forces

remain constant and there is no net external force acting on the kite, as per Newton's

first law of motion. In the vertical direction, the sum of the forces is zero. So, the

vertical pull plus the weight minus the lift is equal to zero as per below equation [17].

Pv + W – L = 0 (4.3)

In the horizontal direction, the sum of the horizontal pull and the drag must also equal

to zero.

Ph – D = 0 (4.4)

The wind is blowing parallel to the ground and the drag is in the direction of the

wind, while the lift is perpendicular to the wind. Both the aerodynamic forces act

through the centre of the pressure. Since, the forces on a kite are the same as the forces

on an airplane, mathematical equations can be used to develop in order to predict the

airplane performance and the aerodynamic performance of a kite. In particular, the lift

and the drag equations, shown on the upper right side of the slide, have been developed

to determine the magnitude of the aircraft forces. The lift L is equal to a lift coefficient

CL multiplied by the projected surface area, A multiplied by the air density, r multiplied

by one half the square of the wind velocity, V as described earlier. Similarly, the drag

D is equal to a drag coefficient CD multiplied by the projected surface area, A

multiplied by the air density � multiplied by one half of the square of the wind velocity

V.

The aerodynamic forces also depend on the air velocity and density. In general,

the density depends on the location of the kite on the earth. The higher the elevation,

the lower is the density. The standard value for air density � at sea level condition is

given as [17]:

ρ = 1.229 kg/m3

49

Figure 4.10 Free body diagram of kite

4.4.1 True and Apparent Wind

Apparent wind is the vector sum of the true wind and the inverse of the ship’s speed.

This means that the apparent wind differs from the true wind in both heading and speed.

The actual angle of the sail to the wind is the difference between the angles of the ship

sailing to the apparent wind.

It can be summarized that when a ship is sailing upwind, the speed of the apparent

wind is always greater than the true wind. When sailing downwind, the apparent wind

speed is usually less than the true wind. The direction the apparent wind comes from is

always shifting forward towards the true wind (refer to Figure 4.11).

50

VA2 = VT

2 + VS2 – 2VTVScos� (4.5)

� = arcsin (VT/VA × sin�) (4.6)

Figure 4.11, True wind and apparent wind

4.4.2 Wind speed

As the flying altitude of the kite is supposed to be within the surface layer of the

atmosphere and this is where the occurring wind is dominated by pressure differences

and hence no geotropic wind occurs, the variation of wind speed with altitude can be

expressed by a logarithmic profile (Treon, 18):

Apparent Wind

True Wind

Vessel Speed

Vessel Speed

�

�

51

W (z) = Clogln(z/z0) (4.7)

Clog = uref / ln(zref / z0) (4.8)

4.5 Propulsion Force

Based on the theory that has been discussed earlier, the propulsion force

analysis of the aerodynamic force, FP

is given as shown in Figure 3.12. The propulsion

force can be illustrated below as:

FP

= L x sin � – D x Cos � (4.9)

Figure 4.12 Propulsion force acting on the ship

4.6 Kite dimension

The cross sectional area of a kite is similar to an aerofoil. As mentioned earlier

the NACA 4415-63 is selected for this study. Figure 4.13 shows the dimension of kite.

52

Figure 4.13 Cross Section of the kite

a = 13m

b = 30m

Area, A = 390m2

AR = b2/S = 2.308

The kite dimension was determined based on the literature review on the current

maximum size of kite dimension can be installed onboard the vessel.

4.6.1 Angle Of Attack

After the dimension of the kite has been finalized, software known as the

Design Foil (25) is used to simulate the Lift and Drag coefficients. Based on that, the

a

a

b

53

graph below is plotted by using the data from the Design Foil. NACA type 4415-63

with angle �=4° is chosen because it has the highest CL/CD ratio. Detail of calculation

as per Appendix D.

Figure 4.14 Variation of CL/CD ratio with angle of attack

4.7 Control System and Routing

The control system essentially comprises an auto pilot, which controls the

altitude and flight path of the towing kite on a winch act. It is located on the bridge and

is fully automatic and includes the preset instructions for launching and recovery of the

system as well the emergency procedures shows in Figure 4.15.

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Figure 4.15 Control system of the SkySail technology (17)

The kite system on which the wind acts, is connected via the force transmission

point, winch and communication paths, is represented by the lines, to the onboard

system to a user interface, which comprises a control system that not only controls the

position of the kite but also emits the necessary control commands to the prime mover

and to the vessel rudder. The onboard system is connected to the element on which the

wind acts via various communication points which allow the kite system to process

important information for the onboard system, on which the wind acts. The onboard

system is preceded by a navigation system which maintains and transmits the route to

the onboard system. It also provides the cost, the time, the speed and wind utilization as

well as the direction and strength of the wind. The information on the wind may also

include a parameter which characterizes as to how gusty the wind maybe. In addition,

this may also include information relating to the condition of the sea and to the vessel

movement resulting from it. The navigation of the vessel is assisted by the navigational

information base (moving map). The course, wind and wave information is used to

55

generate signals which drives the onboard system and results in the appropriate

adjustment of the kite system.

The onboard system also produces drive signals for the prime mover and for the

rudder. The navigation system is driven by a route system, which determines the course

of the vessel. The operation of the vessel is based on the economic status that has been

decided upon. The data can also be received by another vessel equipped with the

system according to the invention and can be used for updating the local weather

conditions. An emergency system provides the required control commands in the event

of an unpredicted happening which necessitates immediate action in the form of an

emergency maneuver (17).

4.8 Ship Resistance

The power curve of the ship (refer to Appendix B) has been used to convert

from the main engine output power to the resistance experienced by the ship. Figure

4.16 shows ship resistance curve experience by the MT Bunga Melati Series.

Figure 4.16 Ship resistance curve

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4.9 Propulsion Estimation

This section shows the method to determine the propulsive force including a

few parameters such as drag coefficient, CD, lift coefficient, C

L, propulsive force, F

P,

lift force, L and drag force, D. The calculation is based on vessel route. As a result FP

value from each direction can be determined. These values will be correlated with the

main engine thrust to get the percentage of power saving. The steps to determine the

percentage of power saving are given below.

a. Propulsion force estimation

b. Power saving estimation

To obtain propulsion force, literature reviewed shows that the aerodynamic

force FT will be divided into two components, FH

and FP.Procedures to obtain FP are

shown below while Figure 3.17 shows their overall process:

i. Determine VA

values based on the values of VT

and VS.

ii. Determine angle of apparent wind, �.

iii. Determine dynamic pressure, q.

q= ½ x � air

x VA

2

iv. Determine L and D. By using Design Foil Program, the NACA 4415-63 was

designed to obtain the CLand C

D

` 2

2

1VSCL L ρ××= , 2

2

1VSCD D ρ××=

v. Obtain FP.

.

F

P = L x sin � – D x cos �

57

Figure 4.17 Overview of process to determine propulsion force

Besides that, procedures to obtain power saving is shown below and Figure 4.18

shows their overall process:

i. from the results of the propulsive force, determine the total resistance, RTotal

ii. determine thrust power, PT, delivered power, P

D, shaft power, P

S and brake

power, PB

iii. estimate percentage of power saving

58

Figure 4.18 Overview of process to determine power saving

59

CHAPTER 5

RESULTS AND DISCUSSION

5.1 Route Analysis

As mentioned in the methodology section, two round trips (four routes) have

been chosen for this study; the first round trip was from the Middle East to Singapore

and the second from Singapore to Taichung. Chemical vessels, MT Bunga Melati

Series which consisted of seven vessels were selected for this study. Data from the

daily noon reports of the vessels was collected for a period exceeding two years (May

2007 to September 2009).

For analysis purposes, Google Earth (26) was used to monitor and track the

route as well to collect the noon reports daily from the vessels under study. Each route

was broken into sectors and the route from Singapore to Taichung was divided into two

sectors while the route from Singapore to the Far East into three sectors as illustrated in

Figure 5.1 and 5.2.

60

Figure 5.1: Route from Singapore to the Middle East - 3 sectors

Figure 5.2: Route from Singapore to Taichung (Far East) – 2 sectors

61

To determine each sector, the longitude and latitude were divided to mark the

sectors. A summary of the sectors is given in Table 5.1.

Table 5.1 Route Sectors Singapore to Jeddah Singapore to Taichung From To From To Sector 1 6.3N, 94.2E 5.8N , 83.4E 24.2N, 120.1E 12.1N, 112.6E Sector 2 5.8N, 83.4E 14.1N, 62.9E 12.1N, 122.6E 1N, 104.5E Sector 3 14.1N, 62.9E 12.1N, 46E

Sectors were introduced to analyze the daily noon reports data so as to ensure

the data collected was reliable in terms of position and wind direction. The voyage from

Singapore to Taichung was expected to take approximately five days; hence there were

two marked sectors. For Sector 1, the estimation was that it would probably take about

three days while for Sector 2 the voyage would be only for two days. For the route from

Singapore to Jeddah, three sectors were marked. It was estimated that the number of

voyage days for Sector 1 would be two, for Sector 2 about four and for Sector 3 about

three respectively.

5.1.1 Route Results

The daily noon reports were collected for a period of over two years. The data

collected was compiled and summarized into monthly basis. The analyses carried out

were to determine wind behavior in terms of speed and direction throughout a period of

one year for the following routes:

1. Singapore to Jeddah, Saudi Arabia

2. Jeddah, Saudi Arabia to Singapore

3. Singapore to Taichung, Taiwan

4. Taichung, Taiwan to Singapore

62

Since the data from the noon reports only indicated the force and wind direction, the

Beaufort scale (refer to Appendix C) was used to convert the data of the wind speed

into knots and wave heights (27). The wind direction was also converted into degrees

for analysis in Sector 1 with ship course at 266 degree shows in Table 5.2. (Refer to

Appendix C for detailed calculation.)

Table 5.2 Ship data converted to wind speed using the Beaufort scale

No Port Ship Name

Power (BHP)

Lat Long SPD Wind Dir Force

Wind Dir

Force

Wind Speed (Knots)

Wind Speed (m/s)

1 JEDDAH MT5 7798 6.4N 93.4E 15.6 NEx3 45 3 8.5 4.4

2 JEDDAH MT6 7640 6.2N 88.5E 15.4 Nx2 0 2 4.5 2.4

3 JEDDAH MT5 7945 5.9N 87.3E 15 NEx3 45 3 8.5 4.4

15.33 Average 60 7.2 3.7

The converted data presented in Table 5.2 was used for analysing the wind

speed for each route, and the results were plotted to determine the wind behavior

throughout the year. The analyses revealed the months favourable for operating a kite

on the selected route.

63

Figure 5.3 Wind Speed on Monthly Average (Singapore to Jeddah)

From the Figure 5.3, it can be concluded that the suitable months to launch the

kite are from the month of April to September due to the present of high force of the

wind. The wind speed however, according to the graph was recorded highest in the

month of July. Sectors 2 and 3 showed that there was consistence in the wind speed but

however for Sector 1, a lower wind speed was recorded as compared to Sectors 2 and 3.

This was due to crossing the Andaman Sea and the Bay of Bengal in Sector 1 while the

voyages of Sector 2 and 3 crossed the Indian Ocean.

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Figure 5.4 Wind Speed on Monthly Average (Jeddah to Singapore)

The route between Jeddah to Singapore showed a uniform wind speed for every

month of the different sectors. From the graph the highest wind speed was recorded

generally from January to February and from May to December. In order to launch the

kite, the wind speed required has to be above 8.5 knots in order to capture the

maximum force generated by the wind. But however, for the months between March

and April, the wind speed was below 8.5 knots and therefore the launching of a kite

was restricted.

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Figure 5.5 Wind Speed on Monthly Average (Singapore to Taichung)

For the other route, between Singapore to Taichung, the graph shows

inconsistence in terms of wind speed. It can be seen, that the wind speed kept changing

from month to month and the possible months to operate kites were January, February,

May, and July to December for all sectors. For the rest of the other months, kites were

not possible to be launched due to the unfavourable wind speed.

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Figure 5.6 Wind Speed on Monthly Average (Taichung to Singapore)

For the last route between Taichung to Singapore, the wind speed was almost

similar for every month except for the months of October to December. In order to have

a good kite performance, the only the possible months to operate were from April to

December. For the months of February and July for Sector 1, it was not possible to

operate any kites. For Sector 2, February and October were not ideal for launching

them as well. In addition the lowest wind speed was recorded at this sector when

compared to the other routes.

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5.2 Wind Speed Result

Based on the data from the daily noon reports, the wind speed on the vessel

height was collected. By using the formula given by Treon, [18] the wind effect can be

calculated at the height of 300 meters above the level of sea water. Detail calculations

refer to Appendix C. An example of the calculation by using the equation 4.7 shows as

below.

Sample Calculation (February):

Uref = 13knots

Zref = 10m

Z0 = 1m

Clog = uref / ln(zref / z0)

= 13/ ln (10/1)

= 5.6458

W (z) = Clogln(z/z0)

= 5.6458 x ln (300/1)

= 32.2 knots

The wind data at 300 meters sea water level was calculated and the figure below

shows the wind summary on the height of 300 meters for the route of Sector 1, from

Jeddah to Singapore. The highest wind speed was in the month of May while the lowest

was recorded in the month of January as shows in Figure 5.7.

68

Figure 5.7 Wind speed based on months for Sector 1 (Singapore to Jeddah)

Since kites can only be launched in a wind condition above Beaufort Scale 3 or

at 8.5 knots, hence the Figure 5.7 shows that kites can be launched almost every month

except for the month of January but however, it depends on the true angle of the wind

speed the ship is heading through. The angle of the true wind should be at least above

50 degrees to the ship heading. By using the equation 2.5 the apparent wind can be

determined. Table 5.3 shows an example for Sector 1 route from Jeddah to Singapore

with the true wind direction on the ship heading and the apparent wind analysis. For

detail calculations refer to Appendix D.

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Table 5.3 Wind direction based on ship heading

Destination Month � (º) VA (m/s)

Jeddah To Singapore (Sector 1)

January 156 12.48 February 175 13.22 March 127 11.27 April 142 11.92 May 122 11.05 June 37 Nil July 47 Nil August 48 Nil September 37 Nil October 166 12.86 November 177 13.29 December Nil Nil

Based on the Table 5.3, it can be concluded that from the of month of January to

May and October to November kites could be launched due to the high wind speed and

true wind angle to a ship heading above 50 degrees. However, from the month of June

to September, it is not possible to launch any kites due to the true wind angle being

below 50 degrees while for the month of December the wind speed is below Beaufort

Scale 3 or less than 8.5 knots.

5.3 Propulsion Results

The Propulsion Force is the most important factor to consider in this study. As

discussed in the reviewed literature, that when a ship is sailing through wind, there are

two forces, which are the Lift and Drag forces acting on the kite. By attaching the kite

onboard, the resistance experienced by the ship can be reduced. A detailed method of

analyzing this phenomenon has been discussed in the methodology section earlier. In

this section the propulsion force results are discussed under the following headings:

70

5.3.1 Relationship between the angle of attack with CL / CD

The relationship between the angle of attack and CL and CD was determined by

using the Design Foil. The NACA 4415-63 was used for this study. Figure 5.8 shows

the results of the angle of attack with the CL and CD..For detail calculations refer to

Appendix D

Figure 5.8 Relationship between angle of attack with CL/CD

From the Figure 5.8, the CL value increases when the angle of attack is

increased but however, it decreases after reaching the maximum value of CL. On the

other hand, the value of CD increases when the angle of attack is increased and it will

decrease once the angle of attack is almost zero in value. The maximum value of CL is

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1.392 and CD is 0.0361. The angles of attack for both CL and CD are at 15 degrees. For

the calculation of the kite force, the ratio between CL and CD is an important factor.

From the methodology, it can be noted that a Design Foil is used for the calculation and

the highest ratio is at the angle of attack with a 4 degree value to the ratio of 73.6

percent. In addition, from the sail propulsion force equation, a higher ratio of both CL

and CD will give a higher Lift Force; therefore giving a higher Drive Force to the kite

and the ship. The maximum ratio of CL and CD will be used in the analysis in the

following section.

5.3.2 Propulsion force generated at selected route

In order to obtain the propulsion force, a graph can be plotted once the data is

converted to the highest altitude of 300 meters and calculated as discussed in the

methodology section. The following graph has been plotted for every single route to

determine the force generated by the wind on the designated kite.

Figure 5.9 Propulsion force distribution (Singapore to Jeddah route)

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From the Figure 5.9, the propulsion force introduced by the kite was observed to

be higher from the months of April to September for all sectors except for Sector 1. But

on the other hand, for the months from January to April and October to December the

force was observed to be in the lower capacity for all sectors. Therefore, for the months

showing the force at zero value, kites could not be launched due to lower wind speed

and unfavourable direction of the wind speed that faced the ship heading. From the

analysis, the power saving recorded was at 20.25 percent from the normally utilized

power.

Figure 5.10 Propulsion force distribution (Jeddah to Singapore route)

Figure 5.10 showing the route between Jeddah to Singapore, a higher propulsion

force was recorded from the months of May to October especially for Sector 2, while

for other months the average of 50KN was recorded. For Sector 1 from June to

September and December kites could not be launched due to the low wind speed and

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direction of the ship heading to the wind direction, however for the other months it was

possible to launch a kite. Analysis on power saving for this route was the lowest

compared to other routes which recorded 9.42 percent from the normal power used.

This was due to the wind direction speed observed on this route.

Figure 5.11, Propulsion force distribution (Singapore to Taichung route)

For the route between Singapore to Taichung as shows in Figure 5.11, it was

observed that Sector 1 had the propulsion force at a peak for the months of February

and September and for Sector 2 for the months of February, May and October. While

for the other months there was an average propulsion force from 50 to 100 KN. For

Sector 2, for the months of May and June it was not possible to launch any kites as the

wind force and ship heading faced the wind direction. For this route the power saving

was recorded at 12.46 percent.

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74

Figure 5.12, Propulsion force distribution (Taichung to Singapore route)

The last route was between Taichung to Singapore. From the Figure 5.12, it can

be noted that Sector 1 had a higher propulsion force if compared to Sector 2. For Sector

1, it was possible to launch kites for all months except for the months of January, July

and November. For Sector 2, kites could be operated for only six months and they were

January, March to May and August to September but kites could not be launched for

the rest of the other months. The saving power on ship was recorded at 10.28 percent.

Detail of calculation as per Appendix D.

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��

��

��

��

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#�%��

#�%��

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75

5.4 Case Study

Data gathered from noon reports of selected vessels was compiled and analyzed.

The following are a few observations about the data:

1. Only three vessels out of the seven trading vessels frequented between the

Far East to the Middle East .These ships are the MT Bunga Melati 5, the MT

Bunga Melati 6 and the MT Bunga Melati 7.

2. The vessel trade route in the Middle East covers a few ports such as Jeddah,

Yanbu and Adabiyah, while for the Far East route covers ports such as

Ningbo, Ulsan, Taichung, and Zhuhai.

Due to the above observations, the case study was created based on the

following assumption:

1. Fixed route from Singapore to Taichung, Taichung to Singapore, Singapore

to Jeddah and Jeddah back to Singapore.

2. Port stay, maneuvering time, vessel speed, distance and duration of voyage

is shown in the table 5.4 and 5.5 respectively.

Table 5.4 Case Study- Voyage Days

Route Distance Vs Hrs Days Manouv

Total

days

Singapore to Taichung 1908 14.5 132 5 0.5 6

Taichung to Singapore 1908 14.5 132 5 0.5 6

Singapore to Jeddah 4560 14.5 314 13 1 14

Jeddah To Singapore 4560 14.5 314 13 1 14

76

Table 5.5 Case study- Trade Pattern

Portstay (assumed) Hrs Days

Taichung(discharged) 48 2

Singapore/Pgd/Dm 72 3

Singapore 48 2

Dumai 48 2

Jeddah 96 4

Data such as distance, vessel speed, voyage duration in days and maneuvering

time and port stay are used in this case study. Detail of data as per Appendix E.

5.5 Case Study Results

The data from the daily noon reports were collected for a period of more than

two years. However there are a observations as follows.

1. The data collected was only from MT Bunga Melati Series. There were only

three out of the seven vessels trading at a selected route at that time.

2. The route that was only considered for this study was from Taichung to

Singapore and to Jeddah. However the normal trading route of the vessel

was sometimes not consistent as it had to abide to the instructions given by

the charterer. The vessel could also sail up to South Korea and China for the

Far East region, while for the Middle East region the vessel could be

diverted to other ports in India and Europe.

3. To gather more relevant data, the daily noon reports between the selected

routes from Taichung to Singapore and Jeddah was compiled. From that, the

77

case study was introduced to eliminate the unnecessary routes the ships had

to operate.

The details of the calculation of the case study is given in Appendix E. Below is

the summary of the case study in terms of fuel and CO2 savings. The new rules for the

green ship, EEDI and EEOI will also be discussed in this study based on the fuel

savings derived.

5.5.1 Fuel Savings

As explained in the earlier chapter, the sectors were divided for each route.

The table 5.6 shows summarizes fuel savings calculated from each sector. Based on the

table, Sector 2 shows a higher fuel savings as compared to the other sectors. For Sector

3 only the route between Singapore to Jeddah was calculated. It is observed that the kite

is able to contribute 391.53 tons a year on fuel savings. The average fuel saving is

about 9.07% from the normal usage of fuel by applying a kite onboard.

Table 5.6 Summary of fuel savings

1��+� #�%�� #�%�� #�%�� 2��2�� !��#��"(�.�/� �� 3�� 3�� 3��

�� "��2�� !��#��"(�.4/� 3�� 5�� 5� 3��5�

The case study analysis is finalized and the figures given in Table 5.7 are

summarized. Form the table it can be concluded that by applying a kite onboard the

ship, a savings of 9.07% per year can be made and about 63.2% of the usage of the kite

system is recorded for the whole period of the selected route. After eliminating the

unnecessary issues, the vessel’s effective voyage days in the open sea are recorded as

186 days while the port stay is recorded at 88 days. The shortage of 91 days is due to

the maneuvering time and the restricted areas for launching kites. The study was carried

78

out on the assumption that there was no other external resistance to be experienced such

as bad weather or any downtime by the ship.

The voyage time is calculated based on the assumption that the vessel sails at a

constant speed of about 14.5 knots. The CO2 deduction will be elaborated in the next

section.

Table 5.7 Summary of case study

Kite savings per year (%) 9.07 Kite use time per year (%) 63.28 Voyage days per year 186 Voyage hours 4466 Kite use hours 2826 Kite use days 118 Tons CO2 per ton oil burned 3 Port stay (hrs) 88

5.5.2 CO2 Savings

Equivalent to the fuel savings, the reduction of CO2 is also achievable by reducing

the burning fuel. From literature review, it can be established, that by burning one ton

of heavy fuel oil, about 3 tons of CO2 can be produced. Figure 5.13, showing the

potential savings of CO2 can be achieved by reducing the fuel consumption. From the

graph, the CO2 savings are recorded as more than 1000 tons a year for every single ship

fitted with a kite. Detail calculation as per Appendix E.

79

Figure 5.13: CO2 Savings versus Years

5.5.3 Calculated Value Attained for EEDI

As explained in the literature review, the data below collected from a particular ship

and the savings derived will be used to determine the value of EEDI using equation

2.10. The calculation can be summarized in the table 4.6 and 4.7. (Refer to Appendix E

for detail calculation.)

1 Basic Data

Type of Ship Capacity DWT Speed Vref (Knots)

Chemical Tanker 31,972 14.5

$

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&$$$$

&%$$$

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80

2. Main Engine

Table 5.8 Main Engine data for calculate EEDI

MCRME

(KW)

Shaft Gen. PME(KW) Type of

Fuel

CFME SCFME

(g/kWh)

7059 N/A 5294 HFO 3.1144 167.22

3. Auxiliary Engine

Table 5.9 Auxiliary Engine data for calculate EEDI

PAE(KW) Type of Fuel CFAE SCFAE (g/kWh)

551.5 HFO 3.1144 206.72

4. Innovative energy efficient technology

N/A

5. Calculated value of attained EEDI (Basic Power)

= � �!"#$� �%&��$$� ��'(&""��!!�&!� �%&��$$� �")'&("��)�*�)

�� %�#("� ��$&!� ��

= 6.713 (g-CO2/ton. mile)

6. Calculated value of attained EEDI (Basic Power + Kites)

By installing a kite onboard the vessel, it will be assumed that the kite acts an

innovative energy efficient technology. Detailed information is given in the table 5.10:

81

6.1 Innovative energy efficient technology (Kite)

Table 5.10 Innovative energy data for calculate EEDI

feff(i) Peff(i)(KW) Type of

Fuel

CFME SCFME

(g/kWh)

0.51 480 HFO 3.1144 167.22

= � �!"#$� �%&��$$� ��'(&""��!!�&!� �%&��$$� �")'&("��)�+�)&!�� $,)� �%&��$$� ��'(&""�

�� %�#("� ��$&!� ��

= 6.438 (g-CO2/ton. mile)

By considering the applying of kites onboard as an innovative energy efficient

technology, the EEDI can be calculated. From the calculation it shows around 0.3 g-

CO2/ton. mile can be reduced. This is because the EEDI is not allowed in reducing

installed power but can be applied into the innovative energy efficient technology.

Kites are intriguing, but however they only can be operated with a certain amount of

wind speed and wind direction. Even though the impact to EEDI is not obvious, the

actual CO2 pollution can be reduced due to less fuel being burned.

5.5.4 Calculated Energy Efficiency Operational Index (EEOI)

To perform calculation of Energy Efficiency Operational Index (EEOI), routes

between Singapore to Jeddah has been selected. This route contain of three sectors.

Table 5.11 and 5.12 shows the calculations data for ‘Without Kite’ and ‘With Kite”

conditions respectively. The CO2 conversion factor used was 3.114 g/tonne of HFO, as

recommended by IMO. Detail of data as per Appendix E.

82

Table 5.11 EEOI (Without Kite)

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99$1�:��"��

!��(!+��(��

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.; $82��(/�� "��

.2��(/�&�(��%��.��/�

#�%�� 5�� 35� �� 5��9��#�%�� 3�� 35� �� 5��9��#�%�� 5�� 35� �� 5��9��

�� "��99$1� 5��9��

Sample calculation for sector 1 as below:

EEOI (without kite) = "�'&("� �%&��$

�%�#("� �'"!&!�

= 7.14 x 10-6 tonnes CO2 / (tons. nautical mile)

Table 5.12 EEOI (With Kite)

��+��-�2��$6�#)��7!�"��#� ��(8��)�+�%��2��'� �

99$1�:��"��

!��(!+��(��

��:��"��&��

�� !��

.; $82��(/� �� "��.2��(/�&�(��%��.��/�

#�%�� 35� �� 59��#�%�� 5�� 35� �� 59��#�%�� 5� ��35� �� 59��

�� "��99$1� ��59��

Sample calculation for sector 2 as below:

EEOI (with kite) = �("&"#� �%&��$

��%�#("� ��%)!�

= 5.67 x 10-6 tonnes CO2 / (tons. nautical miles)

From the above calculation, it can be seen that the use of kite has significantly

reduced the EEOI of the ship by about 20 %. It can be concluded that kite not only will

83

reduce fuel consumption but also gives better GHG emission index rating as shown by

the reduced EEOI.

5.6 Investment Appraisal Results

Investment appraisal techniques are methods of mathematically comparing

returns or predicted returns of different investment alternatives. For this study, the kite

attached onboard the vessel is able to produced fuel saving by using the wind energy.

So, the payback method will be used to measure of how long the kite initial investment

cost can be turned into money profit in terms of years. The payback method will be

calculated in term of simple payback method and discounted payback method. Below is

the table showing the summary of overall cost after the case study has been done. The

data from Table 5.13 will be used for the payback method calculation.

Table 5.13 Summary of detail cost

Kite System Cost Estimate (USD) 1,000,000 Installation cost USD (5% of system) 50,000 Total Cost (USD) 1,050,000 Total Fuel Savings (t) 391.5 Fuel Density 0.98 Fuel Saving (ltrs) 399.5 Fuel price (USD) 0.461 Total Fuel Savings a year (USD) 184,180 Services Cost USD (7% of system) 70,000 Fuel price yearly increment 10% Service cost yearly increment 5%

5.6.1 Payback Method

The payback method of investment appraisal is used to compare projects that

may be competing for a business's available investment capital. Simple payback

method as a first approximation, the time (number of year) required to recover initial

84

investment cost by considering only the Net Annual Saving. By using above table data,

the simple payback method can be calculated as showing in Table 5.14.

Table 5.14 Simple Payback Method

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%�()��6��>(� �� ?��?�� ?��?�� 5�?�� ?�� 3��?�� 5�?�� ?�� ?�� 5�?�� ?�� 5�5?�� 5�?�� ?�� 3�?�� 5�?�� ?�� 53?�� 5�?�� ?�� ?3�� 5� �� 5�?�� ?�� ?5�� 5�?�� ?�� ?�� 3� �� 5�?�� ?�� ?��

�� 5�?�� ?�� 3�?�� @��%'�<�� 5�?�� ?�� ?3�� --��%�()�6��>�

With introduced the discount rate as brief in the methodology the discounted

payback method can be calculated as below Table 5.15. The discount rate figure

gathered from the shipping industry economic practice.

Table 5.15 Discounted Payback Method

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85

From the Table 5.15, simple payback method will took about 10 years and for

the next following years the additional cash flow will be contributed. While for the

discounted payback method it took about 9 years before the investment turn to profit.

Since the payback method is not consider the present value of money or any increment

on the maintenance and fuel prices, the calculation is only for the first screening

process. In order to make the investment appraisal study is more reliable, the NPV will

be used together with the payback method in order to have more accurate data of

investment. By using the NPV equation on the methodology the below data can be

calculated.

5.6.2 Net Present Value (NPV) Method

In order to make the investment appraisal study more reliable, the NPV will be

used in order to have more accurate data of investment. By using the NPV equation 3.2,

the data below can be calculated.

Initial Cost = - USD 1,050,000

e (service cost) = 0.05

e (fuel) = 0.1

n = number of years

NPV (service cost) = - USD 70,000 [[(1+0.05)/(1+0.086)]n-1]/(0.05-0.086)

NPV (fuel saving) = USD 184,180 [[(1+0.01)/(1+0.086)]n-1]/(0.01-0.086)

86

Table 5.16 Operational NPV

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�� 5��3�� 53553� �?�?��$�� @:�.=#&/� �?��?�

Final NPV = Operational NPV – initial cost

Final NPV = 6,802,442 – 1,050,000

= USD 5,752,442

It can be seen that by using NPV for the service cost and fuel saving, the figure

for final NPV at year 10 is showing higher positive value. That means that the cash

inflows from a project will yield a return in excess of the cost of capital, and so the

study should be undertaken if the cost of capital is the organisation's target rate of

return. With comparing the payback method and the NPV approach it can be concluded

, that the NPV study seen is more reliable comparing to payback method due to the

fuel price increase about 10 percent yearly can be expected as per explain in the

literature review.

5.7 Discussions

In order to conclude the core of the discussion, it is worth reiterating the

objectives of this study. The main objective is to develop a wind assisted propulsion

87

system and to assess its techno economics feasibility.

By completed this study, it can be concluded that objective of this study has

been achievable in term of developing of wind assisted propulsion system and its

techno economy feasibility. The study has been focused at specific type of vessel and

route of voyage.

In route analysis study, the wind speed has been converted to speed at higher

altitude by using Troen’s formula. This is require due to the wind experienced by the

kite is no longer geotropic wind at higher altitude. There is one observation on the wind

data especially for air specific density which is depending on the high of the altitude.

For this study the constant air density has been used at �= 1.229 kg/m3. The wind data

are based on actual data which is collected from selected vessel for period May 2007 to

September 2009. However the wind condition is unpredictable but thru this analysis, it

can be a model that mirrors the reality.

Since the data for real ship resistance is not available, the sea trail power curve

has been used to calculate the resistance experience by the ship at the service speed

14.5 knots. With this method, the RT of 396.27 kN at service speed was calculated.

The propulsion force experience by the kite was calculated for each route and

sector. From the result, it shown the highest force were recorded at 200 kN from month

May to July especially for route between Singapore to Jeddah, Jeddah to Singapore and

Singapore to Taichung. While for other others month and sector, the average propulsion

force recorded between 0- 100kN

Power saving can be derived from the propulsion force generated by applying

the kite onboard the vessel. Based on four selected routes, the route between Singapore

to Jeddah recorded the higher saving at 20.25, while the lowest saving is route between

Jeddah to Singapore at 9.42 percent. The remaining routes, Singapore to Taichung

88

recorded at 12.46 percent saving and route Taichung to Singapore recorded at 10.28

percent.

The aim of investment appraisal is to determine whether the kite is feasible to

be applied onboard the ship in term of economic view. Two methods have been used in

this study, which are payback method and NPV. Based on the results, the payback

period between 9 to 10 years are required. For NPV, it showed a higher positive value

at USD 5,752,442 for 10 years lifespan. It must be noted that i=0.086, eservice cost=0.05,

and efuel=0.10 are used for this study but those values may not totally reflect the truth an

inflation is an extremely fickle thing.

At the end of study, the CO2 emission also calculated based on the fuel savings

derived. On top of that, the new rules called Energy Efficiency Design Index (EEDI)

and Energy Efficiency Operational Index (EEOI) also can be determined. The use of

the kite has improved the performance of the ship with respect to IMO indices for

Green House gas emission standards.

89

CHAPTER 6

CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions

The utilization of wind technology in the shipping industry is becoming a

promising benefit to ship owners. The effective cost of operation and a greener,

unpolluted environmental makes it very much favourable, then, burning expensive,

large amounts of the depleting fossil fuel. With the availability of many a new

technologies at present, ship owners are given a varied selection to choose the best

technology in order to suit the different ships and trade routes. It can therefore be

assumed that, the operation of ships with the latest wind technology looks promising

indeed.

The main objective of this study has been achievable as the potential for

tapping wind energy is possible. With the NPV showing higher positive value, risking

to inventing and applying wind technology would prove to be more reliable for the

shipping industry. The tapping of wind energy however, is subjected to the prevailing

wind conditions and the trade route patterns. Based on the case study, the overall fuel

savings is recorded at 9.07 percent which is considered to be a good result for ship

90

owners to consider using wind technology as a choice for reducing operation costs. If

less fuel is burned, the amount of CO2 emitted to the atmosphere will also be reduced as

well. An estimated reduction amount of 1000 tons emitted to the atmosphere in a year

by every single ship will definitely create a greener world. Beside of that the index for

Energy Efficiency Design Index (EEDI) and Energy Efficiency Operational Index

(EEOI) also able to reduced.

Therefore, it can conclude the kite sail have a good potential means of

producing an alternative energy and that it should be developed and considered in near

future.

6.2 Recommendations

There are several areas in this research that need to be further considered and

investigated. The following are recommendations for conducting future studies:

1) There are many types of wind technology as discussed in the literature reviewed.

There are two different wind assisted new developments and these are the kite

system and the flattener rotor. For further research the other types of devices

that are available can be selected and evaluated to determine as to whether they

are economical and reliable to use on the MISC vessels.

2) There are many types of kite sails and one of these is the ladder mill technology.

In this system kites are arranged together in series and they not only provide

propulsion but also produce electricity by driving the generator. A further study

is required to look into the potential of kites.

3) The study only focuses on the force acting on kites without any concern for the

towing rope. For a better value of propulsion force generated, it’s suggested that

the towing rope be included in future studies for more reliability.

91

4) The launching and retrieval system is also not considered. With the increasing

new technology on kites, the system needs to be taken into account for the next

study in order to get results which are more comprehensive.

5) Since the kite has a low heeling moment due to its low attachment point of tow

unlike normal sails that have high heeling moment the stability is not consider.

Moreover, it tends to stabilize the ship due to the fact that it has a vertical force

component. However, it suggests to include in future study for achieve more

accurate result.

6) This project involves more theory than practical tests; even though the actual

data was collected from the MISC vessels. It is suggested that for the next study

a real model and be tested for actual performance.

7) In this study the daily noon report data was collected for a period of two years

by only focusing on chemical vessels. It is suggested that data be collected for a

period of more than two years on all types of ships crossing selected routes.

8) The structural study on installation of Kite system especially at Forecastle area

is not considered in this study. The structural analysis is not within the scope of

the study, however it’s recommended to consider for future study on installation

the kite system at forecastle area

9) In this study the wind speed is determined by average value which is gathered

from the ship daily noon report data. The power calculates based on the formula

in theory chapter and the details of the calculation as per Appendix D. However,

it’s recommended in future study to use wind energy spectrum for evaluate the

power contribution from the wind.

92

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f

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