LNG Transport

FUTURE OF LNG TRANSPORTATION:VARIOUS PROPULSION ALTERNATIVES The Authors Barun Gupta th

4 year Marine Engineering and Research Institute, P-19, Taratolla Taratolla Road, Kolkata-88 Kolkata-88 E-mail: [email protected]

Kumar Surend Surendra ra Prasad th

4 year Marine Engineering Engineering and Resea Research rch Institute, P-19, Taratolla Taratolla Road, Kolkata-88 Kolkata-88 E-mail: [email protected]

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CONTENTS

CHAPTER: 1 LIQUIFIED NATURAL GAS 1.1 INTRODUCTION 1.1. 1. 1.1 1 WHAT IS NATURAL GAS? 1.2 THE FORMATION OF NATURAL GAS 1.3 NATURAL GAS UNDER THE EARTH 1.4 HOW MUCH NATURAL GAS IS THERE? 1.4.1 NATURAL GAS RESOURCE ESTIMATES 1.4. 1. 4.2 2 WHERE ARE THESE RESERVES? 1.5 WORLD NATURAL GAS RESERVES 1.6 USES OF NATURAL GAS 1.7 WHAT IS LNG? 1.8 P ROPERTIES ROPERTIES 1.9 SOME INTERESTING INTERESTING FACTS FACTS ABOUT LNG LNG 1.1 .10 0 NEED FOR TRANSPORTATION :

CHAPTER: 2 MODES OF TRANSPORTATION

8 8 8 10 11 16 17 19 19 20 21 22 22 23

26

2.1 PIPE LINES:26 27 2.1. 2. 1.1 1 INTERSTATE NATURAL GAS PIPELINES :2.1. 2. 1.2 2 PIPELINE COMPONENTS:28 2.1.2.1 Pipes:28 2.1.2.2 Compressor Stations:29 2.1.2.3 Metering Stations:30 2.1.2.4 Valves:30 2.1.2.5 Control Stations and SCADA Systems:30 2.1. 2. 1.3 3 PIPELINE CONSTRUCTION :31 2.1. 2. 1.4 4 PIPELINE INSPECTION AND SAFETY:33 2.2 CNG: A COMPETITIVE TECHNOLOGY TO LNG FOR THE TRANSPORT OF NATURAL GAS:2.2.1 2.2. 1 COMPRESSED NATURAL GAS:2.2. 2. 2.2 2 SAGA / MOSS ROSENBERG CNG DESIGN 1976:2.2. 2. 2.3 3 MODERN CNG CARRIER CONCEPTS :2.2. 2. 2.4 4 THE CNG TRANSPORT TECHNOLOGY:2.2.5 2.2 .5 CN CNG G VS. LNG 2.2. 2. 2.6 6 ADVANTAGES OF CNG OVER LNG:2.2. 2. 2.7 7 DISADVANTAGES :2.3 TRANSPORTATION B Y LNG CARRIERS:2.3. 2. 3.1 1 CONVENTIONAL LNG CARRIER

35 35 36 36 37 38 40 40 41 42































2.3.2.4 The Shape Of Things To Come:2.3.2.5 To Boil Off ... Or Not?

CHAPTER 3 TRADITIONAL STEAM PROPULSION 3.1 BASIC CHARACTERISTICS :3.2 .2.. MARKET REQUIRMENTS :3.2. 3. 2.1 1 OPERATING ECONOMY 3.2. 3. 2.2 2 ENVIRONMENTAL -FRIENDLINESS:3.2. 3. 2.3 3 SAFETY:3.2. 3. 2.4 4 RELIABILITY:3.2. 3. 2.5 5 REDUNDANCY:3.2. 3. 2.6 6 ‘MAINTANABILITY:3.2. 3. 2.7 7 CREWABILITY:3.2. 3. 2.8 8 OTHERS:3.3 WINDS OF CHANGE:3.4 ALTERNATIVE PROPULSION CONCEPT:-

CHAPTER 4 SLOW SPEED DIESEL ENGINES 4.1 SLOW SPEED DIESEL WITH BOG RELIQUEFACTION :4.2 GASGAS-DIESE DIESEL L ENGIN ENGINE E ALTE ALTERNAT RNATIVES: IVES:-4.2 .2.1 .1 ME-G -GII -- THE DUAL FUEL ENGINE:4.2. 4. 2.2 2 E CONOMICAL :- CONOMICAL E VALUATION VALUATION :- 4.2. 4. 2.3 3 INVESTMENT COST:4.2. 4. 2.4 4 EXHAUST EMISSIONS :4.2. 4. 2.5 5 WHAT’S SPECIAL IN IT-A COMPARATIVE ANALYSIS :4.2. 4. 2.6 6 REDUCED FUEL CONSUMPTION 4.2. 4. 2.7 7 OPERATIONAL SAFETY & FLEXIBILITY 4.2. 4. 2.8 8 F LEXIBILTY LEXIBILTY R EGARDING EGARDING E XHAUST G AS E MISSION MISSION 4.2. 4. 2.9 9 ADVANTAGES :-

CHAPTER 5 DUAL FUEL DIESEL-ELECTRIC PROP. 5.1 AZ 5.1 AZIP IPOD OD PR PROP OPUL ULSI SION ON - ELECTRIC MARINE PROPULSION:5.2 5. 2 CR CRP P AZ AZIP IPOD OD PR PROP OPUL ULSI SION ON - HIGH-EFFICIENCY CONTRA-ROTATING PROPULSION S YSTEM 5.3 5. 3 CO COMP MPAC ACT T AZ AZIP IPOD OD® ® PR PROP OPUL ULSI SION ON - MARINE ELECTRIC THRUSTER S YSTEM:5.4 FIRST LARGE SIZE DUAL DUAL FUEL ELECTRIC ELECTRIC CARRIER:5.5 ADVANTAGES :5.6 FOUR GENERATING SETS:5.7 HIGH TOTAL EFFICIENCY:5.8 OUTLINE OF THE DF-ELECTRIC LNG CARRIER:5.8. 5. 8.1 1 OPERATING ECONOMY:-

44 44

46 46 47 47 48 48 48 48 48 48 49 49 49

51 51 52 56 62 63 63 64 68 68 69 69

71 72 72 74 74 76 77 77 77 78































5.8.5 5.8. 5 REDUNDANCY:5.8. 5. 8.6 6 ‘MAINTAINABILITY’:5.8. 5. 8.7 7 ‘CREWABILITY’:5.8. 5. 8.8 8 OTHERS:5.9 FUTURE OPERATING PROFILES:5.1 .10 0 MARKET INTRODUCTION :-

CHAPTER 6

GAS TURBINE ALTERNATIVES

6.1 AERO-DERIVATIVE MARINE GAS TURBINES :6.2 ADVANTAGES OF MARINE AERO-DERIVATIVE GAS TURBINES:6.2. 6. 2.1 1 O PERATION PERATION : 6.2. 6. 2.2 2 M AINTENANCE : 6.2. 6. 2.3 3 R ELIABILITY ELIABILITY AND AVAILABILITY : 6.2. 6. 2.4 4 E NVIRONMENT NVIRONMENT : 6.2. 6. 2.5 5 N OISE OISE AND VIBRATION : 6.2. 6. 2.6 6 V ESSEL ESSEL DESIGN : 6.2. 6. 2.7 7 P ROPULSION ROPULSION PLANT DESIGN : 6.2. 6. 2.8 8 I NSTALLATION NSTALLATION : 6.3 DISADVANTAGES OF M - DERIVATIVE :- ARINE AERO - DERIVATIVE G AS T URBINES URBINES :- 6.3. 6. 3.1 1 T HERMAL HERMAL EFFICIENCY : 6.3. 6. 3.2 2 LIQUID FUEL QUALITY :] QUALITY RESTRICTIONS RESTRICTIONS :] 6.3. 6. 3.3 3 I NITIAL NITIAL INVESTMENT INVESTMENTS S : 6.4 G AS T URBINE URBINE M YTHS YTHS AND M ISUNDERSTANDINGS ISUNDERSTANDINGS 6.5 MARINE GAS TURBINE APPLICATIONS

CHAPTER 7

GAS TURBINE ELECTRIC DRIVE

7.1 GAS TURBINE ELECTRIC DRIVE COMBINE CYCLE PROPULSION 7.2 THE ADVANTAGES ARE: 7.3 THE DISADVANTAG DISADVANTAGE E ARE: 7.4 NORMAL CRUISING SPEED: 7.4. 7. 4.1 1 LOADED: 7.4. 7. 4.2 2 MANEUVERING : 7.4. 7. 4.3 3 HARBOUR LOAD: 7.4. 7. 4.4 4 CARGO DISCHARGE: 7.4. 7. 4.5 5 EMERGENCY SITUATIONS: 7.5 GAS TURBINE ELECTRIC PODDED DRIVE LNG CARRIER 7.6 GAS TURBINE ELECTRIC DRIVE COMBINE CYCLE PROPULSION 7.6. 7. 6.1 1 THE ADVANTAGE ADVANTAGES S ARE: 7.6. 7. 6.2 2 THE DISADVANTAG DISADVANTAGE E ARE: 7.7 NORMAL CRUISING SPEED: 7.7. 7. 7.1 1 LOADED: 7.7. 7. 7.2 2 IN BALLAST: 7.7. 7. 7.3 3 MANEUVERING :

80 80 80 80 80 81

82 82 83 83 83 84 84 84 84 84 85 85 85 85 86 86 87

89 90 91 91 91 91 92 92 92 92 93 94 95 95 96 96 96 96































7.8 INCREASING LNG CARRIER CARGO CAPACITY

97

CHAPTER 8 RELIQUIFICA RELIQUIFICATION TION TECHNOLOGY

99

8.1 BOI BOIL-O L-OFF FF CY CYCLE CLE:- :- 8.2 NIT NITROG ROGEN EN CY CYCLE CLE:- :- 8.3 CON CONTRO TROL L SYS SYSTEM TEM:- :- 8.4 REDU REDUNDEN NDENCY:CY:8.5 LIQUI LIQUIFICAT FICATION ION PLAN PLANT:T:-

100 100 101 102 103

CHAPTER 9

VOYAGE ANALYSIS

9.1 SEL SELEC ECTION TION OF AL ALTER TERNAT NATIVE IVES S 9.2 ONE ONE-TI -TIME ME INV INVEST ESTME MENT NT COS COSTS TS 9.3 REC ECU URRIN ING G VARIA IAB BLE COS OSTS TS 9.4 9. 4 WH WHAT AT AF AFFE FECT CTS S TH THE E VA VARI RIAB ABLE LE CO COST STS? S? 9.4. 9. 4.1 1 OPERATING ROUTE 9.4. 9. 4.2 2 FUEL FLEXIBILITY 9.4. 9. 4.3 3 VALUE OF LNG 9.4. 9. 4.4 4 PRICE OF HFO 9.4. 9. 4.5 5 MEMBRANE OR MOSS? 9.4. 9. 4.6 6 SINGLE OR TWIN PROPULSOR? 9.5 SHIPYARD PREMIUM 9.6 CONCLUSION

CHAPTER 10

COMPARATIVE STUDY

105 105 105 106 107 107 108 109 111 112 113 113 114

115

10. 0.1 1 COMPARISION BETWEEN STEAM, DIESEL & DIESEL-ELECTRIC118 10.2 10. 2 EC ECONO ONOMIC MICAL AL COM COMPAR PARISO ISON N OF THE DIF DIFFER FERENT ENT PRO PROPU PULSI LSION ON SYS SYSTEM TEMS S 121 10.3 10 .3 RE RESU SULT LTS S 122 10.4 CON CONCLUS CLUSIONS IONS 125 10. 0.5 5 COMPARISON 126































CHAPTER: 1

LIQUIFIED NATURAL GAS 1.1 Introduction

Natural Gas is a vital component of the world's supply of energy. It is one of the cleanest, safest, and most useful of all energy sources. Despite its importance, however, there are many misconceptions about natural gas. For instance, the word 'gas' itself has a variety of different uses, and meanings. When we fuel our car, we put 'gas' in it. However, the gasoline that goes into your vehicle, while a fossil fuel itself, is very different from natural gas. The 'gas' in the common barbecue is actually propane, which, while closely associated and commonly found in natural gas, is not really natural gas itself. While commonly grouped in with other fossil fuels and sources of energy, there are many characteristics of natural gas that make it unique. Below is a bit of background information about natural gas, what exactly it is, how it is formed, and how it is found in nature.

1.1.1 What is Natural Gas?

Natural gas, in itself, might be considered a very uninteresting gas - it is colorless, shapeless, and odorless in its pure form. Quite uninteresting - except that natural gas is combustible, and when burned it gives off a great deal of energy. Unlike other fossil fuels, however, natural gas is clean burning and emits lower levels of potentially harmful byproducts into the air. We require energy constantly, to heat our homes, cook our food, and generate our electricity. It is this need for energy that has elevated natural gas to such a level of importance

































Natural gas is a combustible mixture of hydrocarbon gases . While natural

gas is formed primarily of methane, it can also include ethane, propane, butane and pentane. The composition of natural gas can vary widely, but below is a chart outlining the typical makeup of natural gas before it is refined.

In its purest form, such as the natural gas that is delivered to your home, it is almost pure methane. Methane is a molecule made up of one carbon atom and four hydrogen atoms, and is referred to as CH4. Ethane, propane, and the other hydrocarbons commonly associated with natural gas have slightly different chemical formulas, which can be seen here.































Found in reservoirs underneath the earth, natural gas is commonly associated with oil deposits. Production companies search for evidence of these reservoirs by using sophisticated technology that helps to find the location of the natural gas, and drill wells in the earth where it is likely to be found. Once brought from underground, the natural gas is refined to remove impurities like water, other gases, sand, and other compounds. Some hydrocarbons are removed and sold separately, including propane and butane. Other impurities are also removed, like hydrogen sulfide (the refining of which can produce sulfur, which is then also sold separately). After refining, the clean natural gas is transmitted through a network of pipelines, thousands of miles of which exist in the United States alone. From these pipelines, natural gas is delivered to its point of use. Natural gas can be measured in a number of different ways. As a gas, it can be measured by the volume it takes up at normal temperatures and pressures, commonly expressed in cubic feet. Production and distribution companies commonly measure natural natural gas in thousands of cubic feet (Mcf), millions of cubic feet (MMcf), or trillions of cubic feet (Tcf). While measuring by volume is useful, natural gas can also be measured as a source of energy. Like other forms of energy, natural gas is commonly measured and expressed in British thermal units (Btu). One Btu is the amount of natural gas that will produce enough energy to heat one pound of water by one degree at normal pressure. To give an idea, one cubic foot of natural gas contains about 1,027 Btus. When natural gas is delivered to a residence, it is measured by the gas utility in 'therms' for billing purposes. A therm is equivalent to 100,000 Btu's, or just over 97 cubic feet, of natural gas. 1.2 The Formation of Natural Gas

Natural gas is a fossil fuel. Like oil and coal, this means that it is, essentially, the remains of plants and animals and microorganisms that lived millions and millions of years ago. But how do these once living organisms become an inanimate mixture of gases? There are many different theories as to the origins of fossil fuels. The most widely































gas. At higher temperatures, however, more natural gas is created, as opposed to oil. That is why natural gas is usually associated with oil in deposits that are 1 to 2 miles below the earth's crust. Deeper deposits, very far underground, usually contain primarily natural gas, and in many cases, pure methane. Natural gas can also be formed through the transformation of organic matter by tiny microorganisms. This type of methane is referred to as biogenic methane. Methanogens, tiny methane producing microorganisms, chemically break down organic matter to produce methane. These microorganisms are commonly found in areas near the surface of the earth that are void of oxygen. These microorganisms also live in the intestines of most animals, including humans. Formation of methane in this manner usually takes place close to the surface of the earth, and the methane produced is usually lost into the atmosphere. In certain circumstances, however, this methane can be trapped underground, recoverable as natural gas. An example of biogenic methane is landfill gas. Waste-containing landfills produce a relatively large amount of natural gas, from the decomposition of the waste materials that they contain. New technologies are allowing this gas to be harvested and used to add to the supply of natural gas. A third way in which methane (and natural gas) may be formed is through a biogenic process. Extremely deep under the earth's crust, there exist hydrogenrich gases and carbon molecules. As these gases gradually rise towards the surface of the earth, they may interact with minerals that also exist underground, in the absence of oxygen. This interaction may result in a reaction, forming elements and compounds that are found in the atmosphere (including nitrogen, oxygen, carbon dioxide, argon, and water). If these gases are under very high pressure as they move towards the surface of the earth, they are likely to form methane deposits, similar to thermogenic methane. 1.3 Natural Gas Under the Earth

Although there are several ways that methane, and thus natural gas, may be formed, it is usually found found underneath the the surface of of the earth. earth. As natural natural gas has a low density, once formed it will rise towards the surface of the earth through loose, shale type rock and other material. Most of this methane will































There are a number of ways that this sort of 'dome' may be formed. For instance, faults are a common location for oil and natural gas deposits to exist. A fault occurs when the normal sedimentary layers sort of 'split' vertically, so that impermeable rock shifts down to trap natural gas in the more permeable limestone or sandstone layers. Essentially, the geological formation which layers impermeable rock over more porous, oil and gas rich sediment has the potential to form a reservoir. The picture below shows how natural gas and oil can be trapped under impermeable sedimentary rock, in what is known as an anticlinal formation. To successfully bring these fossil fuels to the surface, a hole must be drilled through the impermeable rock to release the fossil fuels under pressure. Note that in reservoirs that contain oil and gas, the gas, being the least dense, is found closest to the surface, with the oil beneath it, typically followed by a certain amount of water. With natural gas trapped under the earth in this fashion, it can be recovered by drilling a hole through the impermeable rock. Gas in these reservoirs is typically under pressure, allowing it to escape from the reservoir r eservoir on its own.































much myth and superstition. One of the most famous of these types of flames was found in ancient Greece, on Mount Parnassus approximately 1,000 B.C. A goat herdsman came across what looked like a 'burning spring', a flame rising from a fissure in the rock. The Greeks, believing it to be of divine origin, built a temple on the flame. This temple housed a priestess who was known as the Oracle of Delphi, giving out prophecies she claimed were inspired by the flame.

These types of springs became prominent in the religions of India, Greece, and Persia. Unable to explain where these fires came from, they were often regarded as divine, or supernatural. It wasn't until about 500 B.C. that the Chinese discovered the potential to use these fires to their advantage. Finding places where gas was seeping to the surface, the Chinese formed crude pipelines out of bamboo shoots to transport the gas, where it was used to boil sea water, separating the salt and making it drinkable. Britain was the first country to commercialize the use of natural gas. Around 1785, natural gas produced from coal was used to light houses, as well as streetlights. Manufactured natural gas of this type (as opposed to naturally occurring gas) was first brought to the United States in 1816, when it was used to light the

































conductor who adopted the title 'Colonel' to impress the townspeople) dug the first well. Drake hit oil and natural gas at 69 feet below the surface of the earth.































miles from the well to the village of Titusville, Pennsylvania. The construction of this pipeline proved that natural gas could be brought safely and relatively easily from its underground source to be used for practical purposes. In 1821, the first well specifically intended to obtain natural gas was dug in Fredonia, New York, by William Hart. After noticing gas bubbles rising to the surface of a creek, Hart dug a 27 foot well to try and obtain a larger flow of gas to the surface. Hart is regarded by many as the 'father of natural gas' in America. Expanding on Hart's work, the Fredonia Gas Light Company was eventually formed, becoming being the first American natural gas company. During most of of the 19th 19th century, natural natural gas was was used almost exclusively exclusively as a source of light. Without a pipeline infrastructure, it was difficult to transport the gas very far, or into homes to be used for heating or cooking. Most of the natural gas produced in this era was manufactured from coal, as opposed to transport from a well. Near the end of the 19th century, with the rise of electricity, natural gas lights were converted to electric lights. This led producers of natural gas to look for new uses for their product. In 1885, Robert Bunsen invented what is now known as the Bunsen burner. He managed to create a device that mixed natural gas with air in the right proportions, creating a flame that could be safely used for cooking and heating.































regulating thermostatic devices allowed for better use of the heating potential of natural gas, allowing the temperature of the flame to be adjusted and monitored. Without any way to transport it effectively, natural gas discovered pre-WWII was usually just allowed allowed to vent into into the atmosphere, or burnt, burnt, when found found alongside coal and oil, or simply left in the ground when found alone. One of the first lengthy pipelines was constructed in 1891. This pipeline was 120 miles long, and carried natural gas from wells in central Indiana to the city of Chicago. However, this early pipeline was very rudimentary, and was not very efficient at transporting natural gas. It wasn't until the 1920's that any significant effort was put into building a pipeline infrastructure. However, it wasn't until after the World War II that welding techniques, pipe rolling, and metallurgical advances allowed for the construction of reliable pipelines. This post-war pipeline construction boom lasted well into the 60's, and allowed for the construction of thousands of miles of pipeline. Once the transportation of natural gas was possible, new uses for natural gas were discovered. These included using natural gas to heat homes and operate appliances such as water heaters and oven ranges. Industry began to use natural gas in manufacturing and processing plants. Also, natural gas was used to heat boilers used to generate electricity. The transportation infrastructure had made natural gas easy to obtain, and it was becoming an increasingly popular form of energy. 1.4 How Much Natural Gas is there?































of high prices were not caused by waning natural gas resources - rather, there were other forces at work in the marketplace. In fact, there is a vast amount of natural gas estimated to still be in the ground. In order to understand exactly what these estimates mean, and their importance, it is useful first to learn a bit of industry terminology for the different types of estimates. 1.4.1 Natural Gas Gas Resource Resource Estimates

Below are three estimates of natural gas reserves. The first, compiled by the Energy Information Administration (referred to as the EIA), estimates that there are 1,190.62 Tcf of technically recoverable natural gas in the United States.































This includes undiscovered, unproved, and unconventional natural gas. As can be seen from the table, proved reserves make up a very small proportion of the total recoverable natural natural gas resources. The following table includes includes an estimate of natural gas resources compiled by the National Petroleum Council in 1999 in its report Natural Gas - Meeting the Challenges of the Nation's Growing Natural Gas Demand. Information on this report may be found here.

































This estimate places U.S. natural gas resources r esources higher than the EIA, at 1,779 Tcf remaining. It is important to note that different methodologies and systems of classification are used in various estimates that are completed. There is no single way that every industry industry player quantifies quantifies estimates of natural natural gas. Therefore, it is important to delve into the assumptions and methodology behind each study to gain a complete understanding of the estimate itself. There are a myriad of different industry participants that formulate their own estimates regarding natural gas supplies, such as production companies, independent geologists, the government, and environmental groups, to name a few. While this leads to a wealth of information, it also leads to a number of difficulties. Each estimate is based on a different set of assumptions, completed with different tools, and even referred to with different language. It is thus difficult to get a definitive answer to the question of how much natural gas exists. In addition, since since these are all essentially educated guesses guesses as to to the amount of natural gas in the earth, there are constant revisions being made. New technology, combined with increased knowledge of particular areas and reservoirs mean that these estimates are in a constant state of flux. Further

































The EIA, in conjunction with the Oil and Gas Journal and World Oil publications, estimates world proved natural gas reserves to be around 5,210.8 Tcf. As can be seen from the graph, most of these reserves are located in the Middle East with 1,836.2 Tcf, or 34 percent of the world total, and Europe and the Former U.S.S.R. with 2158.7, or 42 percent of total world reserves. 1.6 Uses Of Natural Gas

For hundreds of years, natural gas has been known as a very useful substance. The Chinese discovered a very long time ago that the energy in natural gas could be harnessed, and used to heat water. In the early days of the natural gas industry, the gas was mainly used to light streetlamps, and the occasional house. However, with much improved distribution channels and technological advancements, natural natural gas is being used in ways never thought possible.

































Natural gas is used across all sectors, in varying amounts. The graph above gives an idea of the proportion of natural gas use per sector. The industrial sector accounts for the greatest proportion of natural gas use in the World, with the residential sector consuming the second greatest quantity of natural gas. 1.7 What is LNG?

Liquefied natural gas (LNG) is natural gas that has been cooled to the point that it condenses to a liquid, which occurs at a temperature of approximately -256 deg F (-161 deg C) and at atmospheric pressure. Liquefaction reduces the volume by approximately 600 times thus making it more economical to transport between continents in specially designed ocean vessels, whereas whereas traditional pipeline transportation systems would be less economically attractive and could be technically or politically infeasible. Thus, LNG LNG technology technology makes natural gas available throughout the world. x

Natural gas liquefaction dates back to the 19th century when British

































x

Storage and Regasification, Regasification, to convert the LNG stored in specially made

storage tanks, from the liquefied phase to the gaseous phase, ready to be moved to the final destination through the natural gas pipeline system. 1.8 Properties x x

x

x x

x

Extremely low temperature: minus 260°F (minus 162°C). LNG will float on water - Specific gravity of LNG is about 0.45. - Slightly less than half that of water. Odorless and colorless - LNG looks like boiling water. When exposed to atmospheric temperatures and pressure, it vaporizes to about 600 times its liquid volume. Nontoxic, non-corrosive. Vapor Dissipation - As the vapor warms to minus 160°F (minus 107°C); it becomes lighter than air and will dissipate. The natural gas vaporized from LNG can cause asphyxiation in an unventilated confinement. Explosion limit of LNG: 5 to 15%.

































x

come under attack, and in many states, building programs for new power station have been held up because of safety reasons. Moreover, CO2 emission control from major fuels is recognized as the essential issue related to the greenhouse effect, especially since demand for energy increasing.

Concern over worlds’ diminishing energy resources coupled with a growing awareness of the need to protect the environment, led to an upsurge interest in natural gas and construction of special natural gas carriers. These conflicting demands for more energy and cleaner environment present a considerable problem and natural gas promises to solve both of them, thus it was known as a glamour fuel of 1970’s. Until well into the 20th century, it was considered a nuisance and a byproduct of crude oil production. Only when in remote areas of Wyoming, huge reserves of gas were discovered, nobody thought it was one of the



































Illustration 1:-

According to the U.S. Energy Information Administration (U.S. EIA), natural gas production in the U.S. is predicted predicted to grow from 19.1 19.1 trillion cubic feet (Tcf) in 2000 to 28.5 Tcf in 2020.The 2020.The total U.S. U.S. Demand for natural gas is expected to rise from 2.8 Tcf in 2000 to about 33.8 Tcf by 2020 adjusted for forecasted gains in energy efficiency and conservation). These projections suggest that the U.S. could face a gap of 5Tcf by 2020.





































































CHAPTER: 2

MODES OF TRANSPORTATION 2.1 Pipe lines:The efficient and effective movement of natural gas from producing regions to



































pipelines, but the technical and operational details discussed are essentially the same for intrastate pipelines. Natural gas pipelines are subject to regulatory oversight, which in many ways determines the manner in which pipeline companies must operate.

2.1.1 Interstate Natural Gas Pipelines :-











































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































The proposed diesel solution complies with the IMO limits for NOx emissions and is therefore without any NOx abatement. However, the NOx can, if needed, be reduced to any level by Selective Catalytic Reduction. Reduction.

4.2.5 What’s Special In It-A Comparative Analysis : As mentioned in the introduction, the purpose of making electronic engines is focused around the virtues related to “ensuring fuel injection and rate, as well as exhaust valve timing exactly when and as desired”. desired”. With respect to the exhaust exhaust valve movement, this means changing the ‘cam length’, as illustrated in Fig. by simply changing the point in time of activating the ELVA valve.

Fig. 24: Exhaust Valve Timing

This can be used to control the energy to the turbocharger, both during steady and transient load conditions. .

Fig. 25: Exhaust Valve Closing Time































Smoke-free acceleration is a natural benefit apart from SFOC optimization at any load. Fig. 25 gives an illustration of how already a ‘different cam length’ was implemented on the 7S50ME-C engine in Frederikshavn for 100% load vs. 75% load Thanks to the multitude of possibilities with the ELFI, the proportional valve controlling the servo oil pressure to the fuel oil pressure booster, not only the fuel oil ‘cam length’, but also the ‘cam inclination and angle’ and even the number of activations per stroke can be varied for the fuel oil injection. Fig. 26 illustrates different profiles demonstrated during testing of the 7S50ME-C.

Fig. 26: Injection Profiles

The double injection profile is specially tailored for a significant reduction of NOx emissions as referred to later (see Fig. 32). Fig. 27 shows the selected injection rate on that engine at 75% load, compared with what it would have been with a fixed cam.

Fig. 27: Injection at 75% load, ME-C versus MC-C































Fig. 28: Heat Release at 75% load, ME-C versus MC-C

A better heat release mirrors a better fuel consumption, also because the pmax is higher, see Fig. Such data could of course also be realised on a

Fig. 29: Cylinder Pressures at 75% load, ME-C versus MC-C

mechanical engine, but not while at the same time maintaining the ability to perform at 100% load. In the low end of the load scale, the possibility for controlling the timing and rate of injection gives the possibility to demonstrate stable running down to 10% of MCR-rpm, i.e. 13 rpm against a water brake only. This could be even more stable against a propeller eliminating the need for stopand-go operation through channels and canals and making ME engines particularly suitable for shuttle tankers and lightering vessels, as well as for vessels with greatly greatly varying load profile. General performance performance curves for the the ME-































Fig. 30: Performance Curves, ME-C versus MC-C

In order to avoid too high difference between pmax and pcomp, also this pressure is raised by timing control. As also illustrated, the lower SFOC comes at a price in that the NOx increases. For this reason, the first two modes to be incorporated in the control system of the ME engine, as standard, are the ‘fuel economy mode’ and the ‘low-NOx’ mode. Fig. 31 illustrates the coagency between SFOC, NOx, and pmax/Pcomp pmax/Pcomp for the the two modes.

Fig. 31: Performance Curves, Economy versus low-NOx

It goes without saying that an ME-C engine will comply with IMO’s NOx cap also































The low-NOx mode is intended for areas where lower than IMO NOx limits do or will apply. The change from one mode to the other is a matter of seconds only and, of course, is done while running, as illustrated in Fig.

Fig. 32: 7S50ME-C – 75% load

4.2.6 Reduced Fuel Consumption x

x

x

Fuel injection characteristics can be optimised at a large number of load conditions whereas a conventional engine has to be optimised for the guaranteed load, typically at 90–100 % MCR. Constant pmax in the upper load range can be achieved by a combination of fuel injection timing and variation of the compression ratio (the latter by varying the timing of closing the exhaust valve). Due to this, the maximum pressure can be kept constant over a wider load range without overloading the engine, leading to SFOC reductions at part-load. Monitoring of the cylinder pressures ensures that the load distribution among the cylinders and the individual cylinder’s firing pressure can be kept up to as new standard, maintaining the as new performance over the lifetime of the engine.

4.2.7 Operational Safety & Flexibility The ME engine’s crash stop and reverse running performance are improved because the timing of exhaust valves and fuel injection is optimal for all engine operation scenarios. 9

Faster acceleration of the ME engine is possible because the scavenge air pressure can be increased faster than normal opening

































9

9

Dead slow running and slow steaming are improved significantly as the minimum rpm are 10–12 % of the MCR level, and dead slow running is more regular because the combustion is improved thanks to the electronic control of the fuel injection. The control system of the ME engine includes an on-line overload protection system, which ensures that the engine complies with the load-diagram and is not overloaded in the event that the propeller becomes too heavy running as a result of fouling of the hull and resistance from wind and waves.

4.2.8 Flexibilty Regarding Exhaust Gas Emission The ME engine can be run in different modes, viz. The »Limited exhaust gas emission« mode and the »Low fuel oil consumption« mode. x x

x

Smoke emission at low load is improved. The Alpha Lubricator, which is a computer controlled cylinder lubricator system with intermittent lubrication, enables a reduction in the lube oil dosage. Less weight: approximately 3 t/cyl. for a 600- mm-bore engine.

The ME engine range has proved to be very successful since its introduction. The first ME engine was put into service on the 37,500 dwt chemical tanker M/T Bow Cecil (Odfjell, Norway). This engine, a 6L60MC/ME, has performed as desired for more than 16,000 hours. The ME range of engines is available from the 4S50ME-C through to the worlds most powerful ME engine, the 14K108MEC.The advantages of the ME-C range of engines are quite comprehensive, as seen below:

4.2.9 Advantages :

ower SFOC and better performance parameters thanks to variable LLower electronically controlled timing of fuel injection and exhaust valves at any load

































Control ontrol system with more precise timing, giving better engine balance with C equalized thermal load in and between cylinders



System ystem comprising performance, adequate monitoring and diagnostics of S engine for longer time between overhauls



Lower Lower rpm possible for manoeuvring



Better Better acceleration, astern and crash stop performance



Integrated Integrated Alpha Cylinder Lubricators



Up-gradable Up-gradable to software development over the lifetime of the engine































CHAPTER 5

DUAL FUEL DIESEL-ELECTRIC PROPULSION The dual fuel engine is basically a normal 4 stroke diesel which can utilize natural gas as fuel. The gas is injected into the air intake and a small amount of diesel is added in the combustion chamber to ignite the gas / air mixture. In addition to running on gas, dual-fuel engines can run on MDO. When running on MDO, the dual-fuel engine acts as a normal diesel engine.

In case the supply of gas is interrupted, the dual-fuel engine automatically transfers to diesel mode, without loss of engine power or speed. The transfer from diesel to gas mode is carried out fully-automatic on demand and is possible within one revolution of the engine. The system is extremely environment friendly. When using LNG as fuel there is very little NOx, no SOx and no particle emissions. The reduction of CO2 emissions totals approximately 100,000 mt per year compared to a standard steam-driven LNG carrier. The Dual fuel engines are four-stroke engines which can be run alternatively in gas mode or liquid-fuelled diesel mode. In gas mode it runs as a lean-burn engine according to the Otto cycle. Ignition is initiated by injecting a small amount of diesel oil (pilot fuel), giving a high-energy ignition source for the main fuel gas charge in the cylinder. The ‘micro-pilot’ injection system uses less than 1 % of































LNG cargo boil-off is a very good fuel for the DF engines. The only considerable variation in the gas composition, however, is the nitrogen content such that the energy content content of the the boil-off gas is lower than that of pure methane. The nitrogen content in the LNG vapour can be as much as 30 % in volume especially at the beginning of the laden voyage. This is not a problem for DF engines as they can run on such a gas mixture at their nominal output without de-rating.

Electric propulsion system for LNG carriers

5.1 AZIPOD PROPULSION - Electric Marine Propulsion: Azipod is a podded propulsion system, azimuthing through 360°C, cruising ahead of competition in the 5MW to 30MW class. It incorporates an electric motor mounted directly on an extremely short propeller shaft. The motor drives a fixed-pitch propeller. The motor is controlled by a frequency converter which produces full nominal torque, smooth and stepless, in either direction over the entire speed range, including standstill. The propeller rpm can be optimized































Each Azipod® Azipod® propulsi propulsion on system system is individually individually designed designed and optimized optimized to achieve maximum performance.

































5.3 COMPACT AZIPOD® PROPULSION - Marine Electric Thruster System:-

The Compact Azipod® is a electric thruster solution for smaller vessels, is standardized and modular, with high performance and low operating costs. The system is produced in five sizes from 0.5MW to 4.2MW and is available in propulsion and azimuthing thruster versions.































Increased worldwide utilization and transportation of LNG has initiated several studies to explore alternatives to conventional steam turbine propulsion. For LNG carriers, electrical propulsion provides the highest overall efficiency and benefits for ship builders and for operators of the ship. To the new Gaz de France LNG carrier, a complete propulsion drive system in a redundant electrical configuration is provided. The delivery will include medium speed propulsion motors of a total of 28 MW, medium-voltage frequency converters (ABB ACS 6000), and a propulsion control system. The frequency converters use the Direct Torque Control (DTC) technology, a genuine motor control method developed. The converter technology gives improved performance and controllability of the propulsion system compared to alternative methods, and a simpler electrical power system without harmonic filters.































diesel-electric propulsion will be able to take about 5000 m³ more cargo than a steam-driven ship with same overall dimensions. . The number and size of these sets of course largely depends on the ship size and speed, but also on the envisaged operating philosophy. An LNG carrier with a cargo capacity of some 150’000 m3 will typically require one six- and three twelve cylinder engines. An LNG carrier with a cargo capacity of 200’000 m3 will typically require two six- and four nine-cylinder engines, and a ship of 250’000 m3 cargo capacity will do with two six- and four twelve-cylinder dual-fuel engines. The generated electric power is fed to an electric drive fairly similar to those used on contemporary cruise ships. Two ‘high-speed’ electric propulsion motors drive a fixed-pitch propeller through a reduction gear. Twin ‘low-speed’ electric motors mounted on the same shaft can be selected to drive the propeller without assistance of a gearbox alternatively. For the larger ships, twin screw arrangements can be selected without significantly increasing the complexity of the machinery installation.

5.5 Advantages:The main advantages of electric propulsion are: ¾ ¾ ¾

Reduced lifecycle cost by improving the operational economy with reduced fuel consumption and maintenance cost Increased payload through efficient modularization and flexible location of machinery components Safety and reliability with improved manoeuvrability, high redundancy and































5.6 Four generating sets:The number of engines and the power output of each unit are determined by the shaft power needed and also by the degree of redundancy requested. Generally speaking on a typical 138,000 m3 ship with the need for some 34 MW total engine output, the power plant would consist of four generating sets. The maximum continuous output of these engines are 950 kW/cylinder at 500 or 514 rev/min (50 or 60 Hz respectively) and their thermal efficiency is as high as 48 %. Four engines provide some redundancy if one of the engines is out of service, and also flexibility for the different operating modes such as manoeuvring, waiting off ports, loading and unloading. Additionally, they allow flexible preventive maintenance at sea and during port calls, which is not the case with the steam plant or other single-engine alternatives.

5.7 High total efficiency:Recent studies suggest that the most beneficial solution, both economically and environmentally, for topping up the energy available from boil-off gas is to use forced boil-off instead of diesel fuel oil. This solution, in combination with DFelectric propulsion, is economically very attractive in both installation and operating costs. Recent evaluations in the industry have calculated annual savings in total operating costs of between 2.2 and 2.8 million USD compared with a traditional steam turbine LNG carrier. As the dual-fuel

engine is operated on low-pressure gas, below five bar at the engine inlet, the fuel gas compressor package is essentially similar (only two-stage instead of single-stage) to that already used in the current steam-powered fleet. fleet. The main































through a variable-speed drive system, the propulsion motors. A 500 kW emergency diesel generator set is also installed. The single, five-bladed fixed pitch propeller is driven by two 13.5 MW AC propulsion motors through couplings and a twin-input/single-output reduction gear. There are also two 1000 kW bow thrusters. To enhance the redundancy of the propulsion plant, the main engine rooms and casings are divided with a fire-resistant bulkhead. The main engine rooms are under diminished air pressure. A back-up arrangement of a thermal oxidiser is provided to dispose of boil-off gas during long periods of low-load operation. The service speed of the ship is about 19.5 knots at the design draught of 11.0 m and with 15 % sea margin, which corresponds to 27 MW shaft power. The power for accommodation and machinery ancillary consumers is about 1 MW.

5.8.1 Operating Economy: As dual-fuel engines have the ability to run on both gas and MDO, the choice of fuel is up to operator. operator. Several independent studies have however confirmed that that forcing additional boil-off gas to complement the natural boil-off gas is the way to profit most from the potential of the dual-fuel-electric solution. Firstly, forced boiloff gas is cheaper than alternative fuels. Secondly, it is lighter than alternative fuels. Fuel ‘bunkers’ weight is thus reduced, and at a given displacement, the ship will be able to carry more cargo weight. Carrying more cargo volume is enabled by the fact that the dual-fuel-electric solution saves engine room space (Fig. 7). Even when using a small part of the cargo as fuel, a dual-fuel-electric LNG carrier will deliver more cargo to the unloading port in this way.

































machinery efficiency of about 48% and the efficiency of the electric power generation machinery will be about 41%, but will consume a substantially higher amount of electric power due to the presence of the liquefaction plant. Adding the cheaper fuel of the dual-fuel-electric LNG carrier to the equation, this solution clearly excels in terms of operating costs (Fig. 8).

































studies including hazard identification, FMEA and hazardous operations studies, have been conducted to further validate the safety of the solution.

5.8.4 Reliability:The diesel engine has proven its reliability in various demanding marine applications, such such as cruise ships. ships. The use of gas gas as compared to to HFO further enhances this inherited reliability.

5.8.5 Redundancy:Electric propulsion systems are in their essence highly redundant, as more or less all primary functions of the system are distributed over more than one component. The dual-fuel-electric installation features multiple generating sets, potentially distributed over multiple engine rooms, has twin transformers and converters, and features twin electric propulsion motors with double windings.

































propeller of about 27 MW. However, future operating profiles of LNG carriers will require more flexibility from the power plant. Already there have been inquiries about ships that would normally operate at about 15 knots, but have to be capable of doing 19 knots on spot cargo trades. It is then very important that the power plant is efficient also in part-load operation. The maximum required electrical power for cargo pumping and other consumers is roughly 6 MW whereas the minimum can be less than 1 MW. As stated previously, the energy in the boil-off gas will vary considerably during the round voyage of an LNG carrier. When converting the energy content available in the boil-off gas of the above-mentioned size of LNG carrier into mechanical power at the propeller shaft using modern dual-fuel engines, figures ranging from the 12 MW in the worst case up to 25 MW at the best can be calculated for the laden voyage. In ballast, the corresponding figures are typically about half, but can be even lower. Thus, even in the best case the natural boil-off would not be enough to cope with the energy consumption, and either forced boil-off gas or supplementary liquid fuel is needed to make up the shortfall. The selection of supplementary fuel depends on the result of a feasibility study taking into account not only the operating profile of the ship but also oil price trends and the availability of bunkers of the correct

































CHAPTER 6

GAS TURBINE ALTERNATIVES Gas turbine is, in essence, designed to burn gas. As electric drive is being increasingly used and accepted, gas turbines are becoming more and more potential as prime movers. When coupled to an exhaust heat utilising steam turbine, fuel efficiency of such a so called COGES plant increases to a very competitive level. Most gas turbines yield around 20..24 MW in COGES use, thus requiring a booster diesel generator set to reach the power level required in a contemporary large LNG carrier. Figure 3 presents a schematic view of such a machinery.

































9 9 9 9 9 9 9 9 9 9

High output; Compact dimensions; Low weight; High torque; Low noise and vibrations; Low emission; Low lube oil consumption; Low maintenance; Rapid on-site engine module change-out; Rapid engine exchange.



































¾ ¾ ¾

Modular gas turbine construction allows for rapid exchange of engine modules, avoiding lengthy on-site repairs; Gas turbine size and weight allows for a complete engine change-out onsite within hours, without dry-docking or extended stays in port; Gas turbine and spares can be air freighted worldwide.

6.2.3 Reliability and availability:



































6.2.8 Installation: ¾

¾ ¾

Gas turbine, control system and ancillaries are packaged on skids, ready for installation in the building blocks in the shipyard, speeding up the construction process; Gas turbine package with ancillaries are factory tested, reducing commissioning time in the shipyard; Gas turbine turbine packages packages and ancillaries are assembled assembled in the factory factory by



































6.3.3 Initial investments: ¾

Initial investment for a gas turbine engine in the 20 - 30 MW class is approximately 15 - 20% higher than in diesel engines of comparable output. For smaller gas turbines, especially derivatives of helicopter engines, the price difference is even higher;

All the above reasons might spell doom for many a marine gas turbine project.



































free power turbine might drop momentarily, but the gas generator will generate sufficient airflow to correct free power turbine speed almost instantly.

Myth: Gas turbines only run on jet fuel.

Fact: Gas turbines are perfectly happy to run on any liquid fuel available, as long as



































Cruise vessels: ¾

¾ ¾ ¾

Combined cycle operation reduces specific fuel consumption to more competitive levels. Usually one gas turbine can service the power requirements of the entire vessel; Lower engine room space requirements allow for an increase in passenger capacity within the same dimensions; Low noise and vibration enhance passenger comfort; No visible smoke makes operations in Alaskan water possible;









































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































Figure 7: Net Revenue Benefits (Trans-Atlantic) ( Trans-Atlantic)

Figure 8: Net Revenue Benefits (Trans-Carribea ( Trans-Carribean) n)

Figure 9 gives an example for the viability of the reliquefaction system. The curve shows the LNG consumption for the diesel-electric version for the given speed. The boil-off-rate is more or less constant at 0.15% /day which are about 100mt/day for a 142,000 m³ ship. The shaded area above the curve indicates excessive boil off. If, for example, the ship was on a trade where it has to sail at only 18.0 knots, knots, then 25 t of excessive excessive boil off would be lost every day without without a reliquefaction plant. The slower the sailing speed the more beneficial a reliquefaction plant can become. Additionally a reliquefaction plant makes the ship more flexible regarding the choice of fuel in the future in the case of non linear fuel price increases.































Figure 9: Example for BOG reliquefaction viability

10.4 CONCLUSIONS Steam turbine installations have dominated LNG carrier propulsion and electric power generation for decades because no suitable alternatives were available. With the market introduction of low-pressure, four-stroke dualfuel engines came the chance to challenge the steam turbine dominance. Dual-fuel engines in combination with an electric drive have turned out to be the most attractive alternative to the traditional steam turbine installation, especially in terms of operating economy and environmental friendliness. The first dual-fuel-electric LNG carrier is about to enter commercial operation, a second vessel is on the building blocks, and a third ship is in the order book. More orders for dual-fuelelectric LNG carriers are imminent. The evaluation has shown that there are clear arguments to move forward from steam propulsion for LNG ships. The slow speed diesel and the dual fuel dieselelectric are equivalent in terms of economic benefits. However the diesel-electric version allows a higher redundancy, increased flexibility as well as greater cargo capacity. A diesel-electric ship fitted with a reliquefaction plant seems to be the most promising solution for current and future demands to LNG carrier propulsion, especially considering the reduced emissions of NOx, SOx and CO2 and future trading and fuel choice flexibility.































10.5 Comparison In order to show the true revenue making potential of gas turbine driven LNGC alternatives, they have to be compared with the current state-of-the-art conventional LNGC. First of all, on the basis of many contact with the LNG shipping community the most likely LNGC configuration was selected on the basis of technological merits. Initially, calculations showed the gas turbine electric podded drive LNGC to have the best revenue making capacity, with its high cargo capacity and highly efficient propulsion system. However, in the light of recent events involving podded drive failures, it seems that the reliability of these systems does not yet comply with the requirements of the LNG shipping industry. The next best alternative, the gas turbine mechanical drive LNGC offers unsurpassed thermal efficiency and high cargo capacity. However, the durability of the reduction gear, clutches and reversing gear for the FPP in commercial marine application is as yet unknown. Some owners have voiced objections to an alternative equipped with a CPP, citing its slightly lower propulsion efficiency. The gas turbine electric drive LNGC combines excellent thermal efficiency and high cargo capacity, paired with the use of proven technology in the power train. Electric drive systems have gained some acceptance within the LNG shipping community, as illustrated by the order for one 74,000 cubic meter diesel-electric drive LNGC at Chantiers de l'Atlantique last year. Reliability, redundancy and revenue are the key words to this propulsion alternative. To check the economic viability of the gas turbine electric drive LNGC, a cost calculation model has been designed using a range of input parameters to calculate long run economic performance under differing circumstances and on different trading routes. Three LNG trades are simulated; the short trade (Algeria - France), the medium trade (Trinidad - Spain) and the long trade (Qatar Korea/Japan). Two different liquid fuel price levels, representing the extremes of the last ten years, have been used to check the survivability of the gas turbine drive alternatives in changing economic circumstances. Six different aero-derivative gas turbines configuration have been selected to take part in the comparison, making this study the first full-scale performance comparison of all major aero-derivative gas turbine makes for commercial marine propulsion.





























































































Three alternative fuel schedules have been used in this comparison: Round Trip BOG + LF: the natural BOG is supplemented with liquid fuel on both the loaded and the ballast trip. The conventional LNGC burns BOG and HFO 380, while the gas turbine electric drive LNGC burns BOG and MGO; Round trip BOG + FVG: on both the loaded voyage and the ballast voyage the full energy needs are covered by the available natural BOG, supplemented with Forced Vaporized Gas (FVG); Loaded BOG + LF Ballast LF: on the loaded voyage the energy requirements are covered by the available BOG, supplemented with liquid fuel. On the ballast voyage only liquid fuel is used. The results are presented in the diagrams below: Long itinerary: itinerary: High (left) v/s Low (right) Liquid Liquid Fuel Prices Prices































Medium Itinerary: High (left) v/s Low (right) Liquid Fuel Prices





























































Short Itinerary:High (left) v/s Low (right) Liquid Fuel Prices































There are a number of preliminary conclusion to be drawn:

First of all, the cargo quantities delivered by all gas turbine driven LNGCs are substantially higher than that of the conventional LNGC, which translates in additional income; Quite surprisingly, high liquid fuel prices are actually favourable for the gas turbine propulsion system. The explanation is that the thermal efficiency of the gas turbine based propulsion propulsion plants is so high that the effects of high liquid fuel prices on the total operating cost are much less than for the steam turbine powered conventional LNGC. On the loaded voyage, the gas turbine driven LNGC hardly needs any liquid fuel, while the conventional LNGC relies on liquid fuel for about 40% of its total energy requirements; On shorters trades, the effects of an increase in cargo capacity are more pronounced than on longer trades. On the short trade, a gas turbine electric

































return on investment, but it will always be substantially higher than the ROI of conventional LNGCs. Fuel costs for long ballast voyages on liquid fuel only are indeed higher than those of conventional LNGCs, but much lower fuel cost for the loaded voyage more than compensate this disadvantage. This makes the gas turbine powered LNGC also suitable for the carriage of spot cargoes, which sometimes requires longer ballast voyages without heel; The gas turbines GT1, GT2, GT3 and GT6 show almost identical performance, which brings increased competition to LNGC propulsion market, currently dominated by two Japanese steam turbine manufacturers. The resulting effect on the general price level for LNGC newbuildings can be very beneficial for owners considering fleet extentions or renewal. Additional calculations show that, under certain circumstances, it is economically feasible to re-engine a conventional LNGC with a gas turbine electric drive power plant incorporating gas turbine types GT1, GT2, GT3 or GT6, even if the cargo capacity is not increased. However, the conversion should take place early in the charter for the conversion to be profitable and the vessel will not have the same flexibility and high ROI as LNGCs especially designed to exploit the benefits of gas turbine propulsion to the maximum.































REFERENCES:1. Ole Grøne: Grøne: “ME “ME engines engines – the the New Generati Generation on of Diesel Diesel engines”, engines”, Motorship Conference, Hamburg, 2003 2. T. Fukuda, Fukuda, M. Ohtsu, Ohtsu, M. Hanafusa, P. S. Pedersen Pedersen,, ,, O. Grøne, Grøne, O. O. Schnohr: Schnohr: “Development of the World’s First Large-Bore Gas-Injection Engine”, CIMAC 1995 3. Peter Skjoldage Skjoldager, r, Tore Lunde & Eirik Melaaen: Melaaen: “Two-str “Two-stroke oke DieselEngine DieselEnginess and Reliquefaction Systems for LNG Carriers”, Motorship Conference, Hamburg, 2003 4. Off Officia iciall site of “HANSA “HANSA MARITI MARITIME ME INTERN INTERNATI ATIONA ONAL”. L”. 5. Off Officia iciall site site of “MAN“MAN-B&W B&W MCMC-C C ENGIN ENGINE”. E”. 6. Off Officia iciall site site of “MAN“MAN-B&W B&W MEME-C C ENGIN ENGINE”. E”.































16. “Cost Analysis of Fuel Cell System for Transportation – Pathways to Low Cost,” Thijssen et al., Presentation to DOE, August 2001. 17. “Comparing the Benefits and Impacts of Hybrid Electric Vehicle Options,” Browning et al., EPRI Technical Report 1000349, July 2001. 18. “Fuel Cell Handbook on CD “(4th Edition), U.S. Department of Energy, Office of fossil Energy, Federal Energy Technology Center. November 1998. 19. “C.E. (Sandy) Thomas”, et.al. Integrated Analysis of Hydrogen Passenger Vehicle Transportation Pathways. National Renewable Energy Laboratory, March, 1998. 20. “Shimshon Gottesfeld” . Polymer Electrolyte Fuel Cells. Advances Electrochemical Science and Engineering, Vol.5, Wiley-VCH, 1997.

in

21. “Fritz R. Kalhammer, “et. al. Status and Prospects of Fuel Cells as Automotive engines. Prepared for the State of California Air Resources Board, July, 1998. 22. “For Government and Commercial Applications”. http://www.lerc.nasa.gov/ www/RT1995/5000/ 5420p. 23. “Solar-Powered Plane Flies to New Record Height” — One Step Closer to a Commercial Satellite Substitute. http:// www.aerovironment.com Van Norstand































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