gas as a fuel for non-gas ships – cause for concern

7/29/2019 Gas as a fuel for non-gas ships cause for concern

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No 1/12May 2012

Gas as a fuel for non-gas ships cause for concern?

By Alan N. Campion CEng CMarEng FIMarEST FHEA

ABSTRACTThis paper relates to the current drive to use LNG as the main fuel for propulsion and

auxiliary machinery on non-gas ships a move that has obvious benefits in both

environmental and economic terms. The author examines whether there might be someserious cause for concern if this is carried out without proper management and control, given

the vast differences between conventional fuels and LNG. It is based on a lecture delivered atWarsash Maritime Academy to a meeting of the Joint Southern Branch of RINA-IMarEST

on 12 January 2012.

The views expressed in this paper are those of the author, and do not necessarily represent

the views of either the IMarEST or Warsash Maritime Academy.

CONTENTS

Conclusion .................................................................................................................... 2

History ........................................................................................................................... 2

Benefit to the Environment? ....................................................................................... 2Landmarks.................................................................................................................... 3

Regulation gas ships .................................................................................................. 5

Safety Record and LNG Shipping Incidents ............................................................. 6

Keeping it Cool ............................................................................................................. 7

Propulsion Systems ...................................................................................................... 7

Dual fuel boiler + steam turbine ................................................................................. 7Dual Fuel Medium Speed Diesel Electric .................................................................. 8

Slow Speed Diesel plus Reliquefaction and Dual Fuel Operation ............................. 8

HP Gas Supply ........................................................................................................... 9Methane Slip? ........................................................................................................... 10

Recent Developments ................................................................................................. 11LNG Expands ........................................................................................................... 11

Questions ..................................................................................................................... 11

LNG and CNG............................................................................................................ 12CNG and Temperature ............................................................................................. 12

JouleThomson Effect ............................................................................................. 12

Release of Compressed Fuel Gas .............................................................................. 13

Comparing Fuels ........................................................................................................ 14


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Regulation ................................................................................................................... 14

LNG Cargo: LNG Bunkers ....................................................................................... 15

Training? .................................................................................................................... 15TrainingGas Ships ................................................................................................ 15

Draft IGF .................................................................................................................. 15Specialised Training ................................................................................................. 15

Training Delivery ..................................................................................................... 16

Training: Draft IGF .................................................................................................. 16TrainingSeafarers Only? ...................................................................................... 16Assessment ............................................................................................................... 16

Training: Summary .................................................................................................. 17

Outcomes? .................................................................................................................. 17

Conclusion: Prevention is Better Than Cure ............................................................ 17

Bibliography: .............................................................................................................. 18

CONCLUSIONNever one to be conventional, I am going to start with a conclusion.

Not mine I hasten to add this is part of the conclusion to the 1997 Presidential address to

the IMarE (as it was at the time). The address was entitled The development of LiquefiedNatural Gas Carriersa Marine Engineering Success and was given by the then president,

the late David Cusdin:

The ships have earned themselves an excellent safety record and it is of the utmost

importance that it is kept that way. Much of the improvement in the performance ofthe ships has been as a result of the work of the seagoing and ex-seagoing marine

engineers who have been and are working on all aspects of the many gas projects.

The LNG shipping business is, I believe, a success story for marine engineering andthe seafarer. (Cusdin 1997)

I intend to explore whether or not the same conclusion might be drawn 25 years later in 2022

regarding the use of gas as fuel in non-gas ships, bearing in mind that 2022 is now only 10

years away.

HISTORY

To be fair to those with limited knowledge of LNGand its transport by sea I will start with a brief history

and overview of LNG, LNG ships, and the

development of the different modes of propulsion

before examining LNG as a fuel for propulsion of non-gas ships.

Benefit to the Environment?Much is said about the environmental benefit of using LNG as a marine fuel; Table 1

summarises the main ones, based on a vessel with a nominal daily consumption of 100t HFO.Due to LNG having a heating value (or calorific value) about 28% higher than HFO the fuel

consumption could be reduced by as much as 22% per day. That said, over twice the volume

of LNG will be required due to the low density of the liquidtypically below 0.44.

Fig 1: Methane Pioneer(1959)


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Each tonne of LNG burnt will produce 0.4t

less CO2 than each tonne of HFO; the

overall result of the reduced consumptionand reduced CO2 resulting from combustionis a decrease in CO2 emissions of up to 31%.

LNG contains no sulphur, so there can be no

sulphur oxides produced; also particulate emissions due to ash etc. are negligible when using

LNG as fuel. NOx emissions are also reduced, and no sludge is produced through fuel oiltreatment.

LNG may contain between 65% and 99.5% methane, the remainder being a mixture of

ethane, propane, butane and nitrogen, in differing proportions depending on source and theproduction process. It is normally carried at a little over atmospheric pressure and 1m of

liquid methane will expand to form about 630m of gas.

Methane is a colourless, odourless, hydrocarbon with 1 carbon and 4 hydrogen atoms, thelightest compound in the paraffin (alkane) series. It has a boiling point at atmospheric

pressure of163C where the liquid density is 423kg/m. At this temperature most normal

shipbuilding materials will become brittle, and may crack. The actual boiling point and

density of an LNG cargo will vary with the constituents. The temperature is maintained byallowing the cargo to boil, and removing vapour from the tank to maintain the pressure just

above atmospheric. This vapour is commonly burned in the ships boilers instead of fuel oil,

and originally any not required for the ships use was vented to atmosphere. Since that timemethane has been identified as the second most abundant greenhouse gas after CO2 1t

methane having the same environmental effect as about 21t CO2. When burnt, however, each

tonne of methane only produces 2.75t CO2, so venting is avoided wherever possible. The

different options for burning the boil off gas will be examined later.LNG vapour is flammable when mixed with air in the ratio 5-15%

v/v, and requires around

0.3mJ ignition energy to start a flammable mixture burning. This is a little less than would be

experienced due to a static discharge from a hotel room door after walking on a nylon carpet,but, to put it in perspective, it represents 17 the energy required to ignite the hydrogen given

off during battery charging (flammable range 4-76%v/v). Acetylene requires about the same

ignition energy as hydrogen and has a flammable range 2100%.

LANDMARKSTransport of LNG of on river barges in the US to the cattle markets in Chicago for use as a

cooling medium was initially proposed in 1915, but the first seaborne cargo of LNG was

carried from Lake Charles, La, to Canvey Island UK in 1959 by the converted cargo shipMethane Pioneer which had conventional diesel propulsion (Nordberg 2000bhp); the

pressure in the vertical cylindrical cargo tanks was controlled by venting vapour. Six furthertrips followed the initial trial.

Building on the experience gained from this the Methane

Princess andMethane Progress were delivered to British Gas in

1964 to carry LNG from Arzew (in Algeria), also to CanveyIsland, on a 15 year contract. These 26 500m

3ships were finally

Table 1: Environmental Benefit

Fig 2: Methane Pri ncess


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scrapped in 1986 and 1997 respectivelya considerably longer life than the original 15 year

contract indicated. They were fitted with Conch prismatic tanks and 12 500shp steam turbinepropulsion; they were the first to use boil-off gas from the tanks as fuel, on-board

reliquefaction being regarded at that time as uneconomic.

Simultaneously with the development ofMethane Princess and Methane Progress Frenchcompanies were developing a range of cargo systems for carrying LNG from Algeria to

France; three of these were trialled in 1962 in Beauvais, a converted liberty ship. Following

these trials the Jules Verne was built, and delivered in 1965; a similar size to the MethanePrincess and Methane Progress, she was built to a Gaz de France design with seven 9%Nickel steel cylindrical tanks using PVC and Perlite insulation, and propulsion power was

developed by a Parsons 15 000shp steam turbine plant. Re-named Cinderella in 2004 she

was finally scrapped in 2008a 43 year commercial lifespan.

The next significant step was the delivery in 1969/70 of the 71 500m3Polar Alaska and

Arctic Tokyo for trade between Alaska and Japan. Still trading over 40 years later as the SCF

Tokyo and SCF Alaska, they feature the Gaz Transport Invar and Perlite NO82 containment

system, and steam turbine propulsion.Hard on the heels of the Alaska-Japan project came the building, between 1972 and 1975, of

seven 75 000m3

near sister ships in France for the Brunei-Japan trade. Due to the location of

the loading terminal the ships were fitted with the means to load via a platform at the stern,with a linked ship-shore shut-down and emergency release system; something now common

in virtually all LNG terminal operations. Five of these ships had the stainless steel and balsa

wood Technigaz Mk1 containment system; two had the Gaz Transport NO82 system. All

were Stal-Laval steam turbine propulsion, 20 800shp, and five are still trading some 40 yearslater.

The next noteworthy development, in 1973, was the 87 000m3Norman Lady, the first vessel

to feature the Moss type spherical tanks, closely followed in 1975 by the Hillialso withMoss type tanks, howeverHilli was the first LNG ship to have a capacity of over 100 000m

3.

Before long the standard size for an LNG ship was in the range 135 000m3

to 145 000m3;

only a few smaller vessels being built.

In 1993 the 89 880m Arctic Sun and Polar Eagle entered service on the Alaska to Japanroute. These vessels had IHI type B self-supporting aluminium tanks the only ones to see

service in the LNG trade and 21 000shp steam propulsion. They are still trading as Arctic

SpiritandPolar Spirit.The next major step, in 2002, was in fact two steps taken concurrently, so arguably this

constituted a leap; the Gaz de France energY featured not only the new GTT CS1 cargo

containment system, but was also the first to feature a Dual Fuel Diesel Electric (DFDE)

system that supplied all the ship electrical power including 26 000hp for propulsion; the boil-off gas was now being disposed of in more efficient medium speed diesel engines rather than

the thermally inefficient boiler/turbine arrangement. The CS1 containment system never

caught on, though large numbers of DFDE vessels have been built since.

A further giant leap took place in 2007 with the entry into service of the first Q-Flex vesselAl Ruwais, with a capacity of 210 000m

3, propulsion by highly efficient twin slow-speed

diesels developing a total of 50 000hp, and with on-board LNG reliquefaction capability. Al

Ruwais was followed in 2008 by the similar in concept, but much larger, Q-Max vessel

Mozah boasting 60 000hp total from twin slow speed diesels. As of August 2011 there were

30 Q-flex vessels in operation, and 14 Q-Max with more to come.

These landmarks in the development of LNG ships are tabulated below:


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Year Ship(s)

Size

(M)

Power

(PS)

1959 Methane Pioneer 5000 2030

1964 Methane Princess & Methane Progress 26 450 12 673

1965 Jules Verne (Cinderella) 25 500 15 200

1969/70 Polar Alaska & Arctic Tokyo (now SCF Alaska & SCFTokyo)

71 500 20 280

1972 Gadinia & 6 sisters 75 000 21 090

1973 Norman Lady 87 600 30 000

1975 Hilli 126 227 40 000

1993 Arctic Sun & Polar Eagle (now Arctic Spirit & PolarSpirit)

87 500 21 300

2002 Gaz de France energY 74 100 26 000

2007 Al Ruwais 210 000 50 000

2008 Mozah 266 000 60 000

Table 2: LNG Ship Development

REGULATION - GAS SHIPS

Gas ships in general and LNG ships in particularhave an exceptional safety record, andthis is not just by chance. In October 1976 a Code for Existing Ships Carrying LiquefiedGases in Bulk, plus a Code for the Construction & Equipment of Ships Carrying Liquefied

Gases in Bulkfor ships built after that date came into effect; they were originally published

by what was then IMCOthe body that later became the IMO; these are known respectivelyas the EGC and GCC codes. Compliance with these was voluntary, but operators of LNG

ships at that time tended to comply.

In 1986 the GCC was superseded by the International Code for

the Construction and Equipment of Ships Carrying LiquefiedGases in Bulk, commonly referred to as the IGC Code as

otherwise it is a bit of a mouthful! This was published as volume

III of the 1983 amendments to SOLAS; and the link to SOLASnow made it mandatory for ships in international trade to comply.

In 1993 the code was updated and the second edition published.

Currently under review, the next edition of the IGC Code isexpected to be ratified by 2014.

The IGC code has been developed through the use of advanced

hazard and risk analysis techniques rather than representing

retrospective controls implemented following incident or disaster,and includes, for example, a requirement to site cargo containment Fig 3: IGC Code


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a minimum distance from the ships side; all cargo pipes must be in the open above the

weather deck and enter the tank from the top. The accommodation may not be situated abovethe cargo area, and there are strict controls over many other matters, but all are based on the

degree of hazard posed by the cargo.

In conjunction with this there are comprehensive minimum requirements for training ofpersonnel operating gas ships, particularly management level Officers; these are detailed in

STCW, and the IMO publish Model courses for guidance. There is also a lot of guidance

regarding best practice that has been collated from the industry promulgated by independentorganisations such as the International Chamber of Shipping (ICS) and SIGTTO, the Societyof International Gas Tanker & Terminal Operators, who have also produced a suggested

competency standard for officers on LNG ships that exceeds the minimum requirement set

out in STCW; training to this enhanced standard is required by many charterers.

SAFETY RECORD AND LNG SHIPPING INCIDENTSThe combined result of all this is an enviable safety record for LNG shipping: as of the 45

years LNG service to December 2009, LNG ships had carried in excess of 59 000 cargoesacross over 150 million nautical miles without loss of life or vessel due to a cargo related

incident. Despite this record, the public perception is that LNG ships are extremely

dangerous.It would be wrong, however, to say that there have been no incidents whatsoever!

Over the same 45 year period referred to above there have been 41 reported incidents

involving LNG ships including 8 collisions; 4 of these involving contact with other vessels, 2

were jetty contact incidents, plus one where an LNG ship alongside was hit by a passingvessel and one where a submarine tried to extend its periscope through the ship.

There have been 4 cargo-related fires two of which

were vent mast fires where venting vapour was ignitedby lightning, one insulation fire during building, and

one fire due to vapour ignition during disconnection.

In total there have been 13 liquid releases, most of

these extremely minor, some resulting in small cracksto strength parts of the vessel, or significant cracking to

non-strength parts; others have caused no structural

damage at all. During this period there have also been5 grounding incidents, none of which led to any cargo

releaseand this includes the1975-builtEl Paso Paul Kayser, shown here in dry-dock after

she had grounded at 17kts fully loaded near Gibraltar in 1979. Even here there was no cargo

release, although the containment system suffered some damage; in fact the cargo wassuccessfully transferred to a sister ship using thePaul Kaysers own pumps before preparing

for docking, and the Paul Kayser continued trading for another 10 years until she was

scrapped in 1985.

I am not of the opinion that these statistics indicate that LNG ships are intrinsically safe; therecord is due to the high standards of regulation and training extant in the industry, and the

engineering excellence that has prevailed over many years.It is worth considering that during same period there were over 100 major oil tanker incidents

that resulted in 700 fatalities and the spillage of over 1m tonnes of oil.

Fig 4: El Paso Paul Kayser


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KEEPING IT COOL

Keeping any low pressure gas cargo cold is quite simple: the tanks are heavily insulated tolimit heat ingress, and to compensate for the small quantity of heat energy that does

inevitably pass through the insulation the cargo is allowed to boil; by extracting cargo vapour

the added energy is removed, thus keeping the cargo tank thermodynamic energy levelconstant, and hence the pressure and temperature stable. With LPG cargoes the gas that is

removed is re-liquefied and returned to the tanks; with LNG cargoes (until recently, that is)

the easiest way of utilising the boil-off gas was as fuel in the ships boilers, hence the use ofsteam turbine propulsion. Part of the rationale permitting the use of LNG vapour as fuel inthis way is that, if heated to above 100C, LNG vapour becomes lighter than air, making

any potential leak into the engine room easier to trap, detect, and extract.

Recent advances have meant that options other than boilers are available for the disposal of

boil-off gas; however even including new-buildings yet to be delivered, almost 70% of LNGvessels utilise steam based propulsion.

PROPULSION SYSTEMSFor many years, it seemed that, so long as there were LNG ships in service, there would

always be a home for the dyed-in-the-wool steam engineer. Boilers raising steam for

propulsion and power generation were the obvious way of disposing of the gas; despite thelow efficiency of the boiler/steam turbine system about 29% this was offset by the low

heavy fuel oil consumption (possibly as low as zero), and the need to dispose of the boil-off

gas safely.

Dual fuel boiler + steam turbineSo, here we have the classic LNG vessel fuel gas supply system ... the BOG is taken from the

tanks by a small, single stage high speed centrifugalcompressor referred to as the Low Duty or Gas

Burning compressor delivering low pressure gas to the

boiler burners via a heater that raises the temperature to

between 25C and 45C. As the machinery spaces areto be maintained safe from the entry of gas gas safe

in other words the safety barrier between the gas-

hazardous and gas safe areas is extended to the boiler,and a gas master valve, shown in green, acts as an

automated safety shut off device (see Fig 4). Before

and after each gas burning session the pipeline between this gas master valve and the boiler is

purged with nitrogen, and gas burning can only be initiated on a register already burning fuel.If the gas master valve should close in response to a safety trip, fuel oil burning will be

automatically reinstated. If more gas is required than can be provided by the naturally

occurring boil-off, liquid is pumped from the tanks through a vaporizer and the extra gas that

is created added to the boiler supply.It therefore seemed, for many years, that this system would ensure that LNG ships would

always provide a potential berth for the steam engineer. However, this was not to be!

Fig 5: Steam plant with gas


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Dual Fuel Medium Speed Diesel ElectricIn or around the year 2000, engine manufacturers developed what was marketed as a new

system for gas ship propulsion; dual fuel medium speed engines driving alternators in a

diesel electric propulsion and power generation system (DFDE) achieving a propulsionefficiency of 43% rather than the 29% achieved when

using steam turbine plant. Actually this was nothing

really newdual fuel medium speed diesels have beenin use in the on- and off- shore petroleum industries formany years, utilising, for example, well-head gases for

fuel. Equally, diesel electric propulsion systems had

been in use for many years

on cruise and containervessels all it really

needed was the vision to

put the two together.As large quantities of effectively free electricity were now

available it was suggested that some of the excess power might

be used for partial reliquefaction and this paved the way for thenext development, Slow Speed 2 Stroke Diesel propulsion with

full reliquefaction of the cargo boil-off gas.

In the dual fuel medium speed engine the fuel gas is injected

into the air stream at each cylinder inlet, compressed along withthe air charge, and ignited by a pilot injection of fuel oileither

HFO or MDO. Compared with the boiler system this requires a

slightly higher fuel gas pressure in the region of 4 6 bar(g). As this pressure cannot beachieved with a single stage centrifugal compressor two stage centrifugal compression is

generally fitted, sometimes with pre-cooling.

Slow Speed Diesel plus Reliquefaction and Dual Fuel OperationIt was calculated that, especially with the new generation larger LNG vessels the so-called

Q-Flex & Q-Max types developed for the Qatar project delivering the full cargo as loaded

by fitting reliquefaction and conventional slow speed diesel engine propulsion withefficiency around 50%, would more than offset the cost of running the reliquefaction plant.

The ships were therefore built with twin slow speed diesel main engines and medium speed

generator engines all running on HFO, plus a reliquefaction plant that featured two stage

compression for the gas process so about 4 6bar(g) again and a nitrogen gas chargedreverse Brayton cycle cooling system.

This was fine, and several ships were delivered, until increasing fuel prices upset the balance,

so that the value of the extra cargo delivered no longer outweighed the fuel cost; this resulted

in a drive to operate the slow speed two stroke engines on dual fuel, which was not a newconcept; in fact David Cusdin referred to it in his 1997 presidential address, and the

manufacturers already had experience with land-based plant. The ships delivered with twostroke diesel propulsion and reliquefaction plant are now scheduled for conversion to dual

fuel operation, and I understand that any remaining new-buildings will be delivered with this

option.

One of the major concerns here, however, is the gas supply to the engine: because of the waya two stroke engine operates taking the fuel gas in with the combustion air is not an option

Fig 6: DFDE Schematic

Fig 7: Gas injection to a

medium speed engine


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and direct injection to the cylinder is required. To get the appropriate quantity of gas into the

cylinder in the required time at the correct part of the cycle a higher pressure is required thanfor boiler, DFDE or reliquefaction systems: the figure generally quoted at present by many

sources is 150-265bar, but I have also seen reference to pressures as high as 360bar.

HP Gas SupplyThere are two main options for producing gas at these high pressures.

The first is to take LNG vapour from storage, and compress it which requires a largecompressor, probably 6-cylinder, 5-stage. If there is insufficient vapour supply from naturalboil-off then a vaporiser would be used to augment the supply. Removing just the vapour will

also lead to a slow change in the constituents of the liquid & hence its characteristics, and the

characteristics of the associated vapoura process known as weathering.

The second alternative would be to compress the liquid by using a multi-stage HP pump, andthen to vaporize the high pressure liquid.

At first glance there seems little to choose between these two alternatives until one

considers both the total work that must be done on the gas, and how this is achieved.In option 1, vapour compression, assuming the starting position is just above atmospheric

pressure, there would need to be several stages of compression typically 5 with

intercooling, to achieve the final result. The total work required to be done on the gas by thecompressor would be of the order of 540kJ per kg gas passing through. If the vaporizer were

required the latent heat energy input to turn liquid to vapour would be 645kJ/kg; a total heat

+ compression energy requirement of 1185kJ/kg.

On the other hand, if we were to use liquid compression + vaporizing, based on the samestarting pressure, the energy added to the liquefied gas during pumping is around 100kJ per

kg, leaving 655 to be added in the vaporizertotal energy requirement 755 kJ/kg.

Fig 8: Comparing Compression and Pumping


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The major difference between these alternatives?

In the compressor-based system energy addition is mainly by way of mechanical means; the

liquid compression + vaporizing option adds most of the energy by using static heatexchange equipment. The vaporizer requirement for both systems would be about the same,

utilising heat energy from the steam produced by the waste heat recovery system which can

therefore be ignored. The major difference would be in the power requirement for thecompressor, being over 5 greater when compared with the pump not to mentionmaintenance considerations.

Methane Slip?

You may have heard the expression Methane Slip; if not you probably will before long!This refers to unburned fuel gas that might be released to atmosphere with the exhaust as part

of the combustion process. In a well managed boiler installation or a direct injection two

stroke slow speed diesel engine plant this will be zero. However the four stroke mediumspeed engine where gas intake is with the combustion air, may present a problem due to the

scavenging overlap that is a normal part of the cycle.

It is the part of the cycle highlighted in red wherethe intake air is used to expel the remaining exhaust

gasthat is the main concern. Because methane has

21 the Global Warming Potential of CO2; methane

slip is often quoted in arguments against LNG fuel ingeneral, although it only affects the 4S engines;

engine designers are making huge reductions to the

amount of gas expelled in this way, although in someolder engines it is possible that methane slip could

negate the environmental advantage of the reduction

in CO2 emissions achieved. Methane slip is highest at

low loads.

Propulsion SummaryTo summarise the different propulsion options:

There are four options available for propulsion of LNG vessels: dual fuel steam or medium

speed diesel power plant, or slow speed diesel plant with reliquefaction; these all feature lowor moderate gas supply pressures. Then there is slow speed dual fuel operation with a

significantly higher gas supply pressure.

Regarding propulsion efficiency, either form of diesel plant has significant energy savings

compared with steam, although methane slip may reduce the environmental advantage of themedium speed diesel solution, especially where conversion from conventional fuel is

concerned.

Regarding the steam option, not only is it inefficient, but there is a great deal of difficulty in

recruiting engineers with appropriate qualifications and experience. The technology,however, exists to use LNG as a fuel source for virtually any type of merchant vessel

whether using slow speed or medium speed diesels for propulsion.

Fig 9: Four Stroke Cycle


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RECENT DEVELOPMENTSSo far I have related everything to ships designed and operated within the strictures of the

IGC code, and STCW training requirements. However, recent environmental and economic

pressures have resulted in a massive interest in LNG as fuel outside this carefully managedand regulated situation. It should be mentioned here that some vessels are already running

with LNG as fuel on coastal routes where international legislation is not necessarily a

major influence.

LNG ExpandsWhen LNG is turned from liquid to vapour the volumetric expansion will be anywhere

between 600 and 630 times, and since 2009 interest in the use of LNG as fuel for propulsion

outside LNG ships has expanded in much the same way, and some interesting proposals haveresulted, some of which, it must be said, show a lack of basic understanding of how the cargo

is used as fuel in existing LNG carriers.

Concept designs have included the prospect of fitting the LNGfuel tanks immediately below the accommodation which I

would suggest is a proposal that can only be based in

economics, rather than being on risk and hazard analysis ofsafety considerations.

Much continues to be written about LNG for propulsion in the

maritime press, with reference to, and quotes from, engine

manufacturers, ship operators, ship builders, and ClassificationSocieties, along with a great deal of comment relating to

emission control areas and the need to reduce SOx, NOx and

CO2all more easily achieved when using LNG as fuel.

Even LPG (which is heavier than air) has been mooted as a possible fuel, and more and more

publicity was given to the potential for the new, green ships with concept designs, and

reports of orders being negotiated and placed for new-buildings and conversions.The one aspect that seemed to cause little concern, only meriting a passing mention (if indeed

any mention at all) was the matter of training for the crew operating the vessel. But it is not

cargo, is it? It is only bunkers. Not the same, surely?In fact it appears that having the bunkering infrastructure in place has now become the major

talking point, so that LNG is readily available as fuel; it therefore seems that the concept of

utilising LNG as fuel is now accepted to the point where it is not really even newsworthy

only the logistical problems in achieving that end create headlines.

QUESTIONS

To my mind this, now inevitable, expansion of the use of LNG fuel to non-gas ships where

the IGC code and STCW requirements regarding carriage of gas as cargo do not apply raises several questions. The first, and most obvious to me, is this: is any training in

operations with this new bunker fuel necessary? If so, why? If it is required, then to whatlevel should it be given?

Assuming training is to take place what about assessment or is knowledge transfer just to

be assumed to take place? Who should supply the training the employer? The equipment

manufacturer? A training establishment?

Fig 10: LNG fuelled

Container Vessel Conce t


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Is it only the shipboard personnel that will need training? What about others involved in the

overall operation of shippingcharterers, agents, and so on?I would like to briefly explore various aspects of these questions, based in both the

technology concerned, and current draft proposals soon to go before IMO, and offer some

possible answers. But first, a few more facts about the use LNG as a fuel in the ways alreadydiscussed, and as proposed for non-gas ships.

LNG AND CNGLNG = Liquefied Natural Gas that is natural gas that has been cooled sufficiently tobecome liquid. It is therefore below the critical temperature of84C, and for low pressure

storage is more likely to be below 160C. At these very low temperatures, of course, most

engineering and shipbuilding materials become brittle. Above the critical temperature the

product becomes natural gas just as you get from the distribution system to your home ifyou have mains gas. If it is not liquid, it is not LNG!

When it is compressed, it becomes compressed natural gas, or CNG, allowing a greater mass

to be stored in the same volume, although the scantlings of the containment will need to besignificantly heavier. When natural gas is stored in this compressed state, even at ambient

temperature, the potential for low temperatures and brittle fracture is not removed, however.

CNG and TemperatureSome reports have suggested that natural gas for ship propulsion could be stored as CNG at

pressures up to 275bar; this is also the pressure generally quoted for the supply of fuel gas to

a slow speed diesel engine on full load, although higher pressures have also been proposed.Depending on the vessels trading area this CNG could be at 37C, 25C or even 0C. How

can this cause concern regarding low temperature?

Even when not doing work in the process, most gases exhibit a fall in temperature whenexpanded; this phenomenon is referred to as the Joule-Thomson or sometimes Joule-Kelvin

effect.

If CNG is expanded from 275bar it does not matter whether it is to 6bar, or to atmospheric

pressure, the effect will be virtually the same.

JouleThomson Effect

The Joule Thomson effect relates to the temperature change in a fluid when it undergoesisenthalpic expansionie expansion with no change in enthalpy, the thermodynamic energy

level; in other words without performing work. This temperature change may be positive or

negative, and at low pressures the change is often negligible and the effect is best illustrated

by use of a Mollier Diagram.On the next page is the Mollier diagram for methanethe major constituent of natural gas.

Included are lines that indicate constant pressures of 1bar(a) (ie atmospheric pressure,

7bar(a), and 275bar. Also shown are the lines of constant temperature for +37, +25, 0, -50, -

75 and -100C.If CNG at 275bar(a) is expanded from +37C to atmospheric pressure, the temperature will

fall to around -50C cold enough to cause physical harm to unprotected personnel, and,assuming sufficient mass, to cool steel to the point where brittle fracture is possible.

From the same pressure and +25C the temperature would fall to below -75C with an even

greater likelihood of embrittlement or personnel injury, and from 0C to below -100C

where the gas is now not just cold, but heavier than air.


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Fig 11: Cooling effect of expansion

Compare this with expansion from 6 bar(g) to atmospheric pressure, where there is very little

temperature change at allonly a few degrees.

Release of compressed fuel gas

There are many incidents that could cause release of fuel gas into the machinery space

potentially resulting in gas contamination of a space nominally safe from such an event.Although any limited release due to pipe fracture, flange gasket failure etc. should be

contained within the negative pressure ventilated protective double-wall pipe system or

trunk-way, other causes of failure are possible. For example injudicious movement of largeengine spares (pistons, liners for example) could carry away the pipe system completely, as

could support system failure due to fatigue resulting from vibration.

Whatever the cause, if we consider 20m of 150mm pipe containing CNG at 275bar suffering

a catastrophic failure so that the contained gas was released to atmosphere it would create, atambient temperature, a gas cloud of about 100m

3 the initial temperature would be much

less of course, probably about50Cbut it would rapidly warm. This 100 m3

of gas when

mixed with air could create up to 2000m3

of flammable mixture at the LFL of 5% by

volume. Not only is this a large cloud of flammable vapour, but such an event would alsorapidly displace a lot of air, reducing the oxygen available to support life, not to mention the

possible effect on a running internal combustion engine. Whilst the likelihood of this type of

event might be low, the consequence would be extremely high, so this is something I believeworth including in risk assessment procedures!

Conventional diesel engine design ensures that rupture of a high pressure fuel pipe results in

release of a minimal quantity of flammable material; one that is liquid and significantly moredifficult to ignite than gas.


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Comparing fuelsHaving looked at some of the possible hazards of LNG as a fuel, I would like to summarise

what I see as the main differences between the main fuel typesdistillate, residual and

natural gas.

Apart from cryogenic LNG at 160C, most fuels will be stored at or above ambienttemperature; similarly service temperatures will vary for all these fuels between ambient and

+140C depending on the machinery design requirement. The limited vapour resulting from

use and storage of conventional fuels is heavier than air; natural gas vapour below 100C isalso heavier than air, but above this temperature the vapour becomes lighter than air. The

flashpoint of conventional fuels for marine use is regulated by SOLAS, and must be greaterthan +60C unless for engines in lifeboats, emergency generators etc, when flashpoints down

to +43C may be permitted. The flashpoint of LNG is significantly lower at 221C,although the auto-ignition temperature is high at 535C595C.

The main non-fire issue with conventional fuels is, of course, pollution not a problem with

natural gas as it will vaporise and disperse quickly. However the large liquid-to-vapour

expansion ratio (1:630) will rapidly result in a large gas cloud with the potential to displaceair resulting in asphyxia, and anywhere from low to extremely low temperatures. This

indicates that there will be significant differences when handling, storing and caring for these

new age bunkers.

REGULATIONI have already mentioned regulation regarding the construction and equipment of shipscarrying liquefied gases in bulk, and the training requirements for the officers and crew.

Does the fact that natural gas, in whatever form, is being used as bunkers make any

difference?

Table 3: Fuel comparison


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LNG Cargo: LNG Bunkers

If we were to compare the potential risks of LNG as bunkers, or as cargo, we would, ofcourse, find no difference at all: it is the same product, merely different quantity and purpose.

However, none of the regulations that apply to gas ships are applicable; they are specific to

gas carried as cargo.At present the only training requirement otherthan individual flag state regulations is in the

Draft Code on Safety for Gas Fuelled Shipsor Draft IGF Code as it is currently known. A

lot of work by a number of people has been put into this document to get to the presentposition, though there still remains much to be done.

TRAINING?

The Training requirement that may (or may not) end up in the finalised IGF is a matter that is

still under discussion at IMO and by the BLG correspondence group to which I am a recentrecruit.

It is fairly obvious that, given the huge differences between handling HFO and MDO bunkers

with >60C flashpoint and handling LNG as fuel that some form of adequate training isessential, always remembering that formal training regarding operations with oil fuel bunkers

and the relevant regulations is included in both deck and engineer officer certification to

augment the experiential learning that occurs naturally during on-board service: neither formof training is available for gas as fuel at present.

Training Gas Ships

For service in gas ships STCW 95 requires advanced training leading to the issue of a tankerendorsement for all personnel who have ... immediate responsibility for loading, discharging

and care in transit or handling of cargo ...(IMO, 1993); however it is not uncommon to find

on LNG ships that many more than just the specified officers (Master, C/E/O, ChOff, 2/E/O,Cargo Eng. for example) have completed this training.

For issue of a Tanker Endorsement (Liquefied Gas) it is necessary that those concerned

receive training in handling allthe gases covered by the IGC code, and there are over 30 at

present. Training for those on non-gas ships using gas as fuel will obviously not need tocover all of these, but I see no reason for it to be less detailed in respect of those gases that

are proposed for use as fuel.

Draft IGFSo, what does the draft IGF code say? When I first read it the proposal was that:

... crew members with direct responsibility for the operation of gas-related equipment on

board should receive special training. The company should document that the personnelhave acquired the necessary knowledge, and that this knowledge is maintained at all times.

(IMO, 2009)

The code then outlines the training requirements: firstly for all members of the operational

crew, who should receive basic safety training, which was designated Category A.

Specialised TrainingFollowing category A training comes categories B and C trainingfor deck and engineer

officers respectively. What constituted this training would be decided by the Master and

Company, who would arrange the training level: based on an evaluation of the concerned

crew members job instructions/area of responsibility on board.(IMO, 2009)


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With all due respect I would question the competence of, for example, a container ship

operating company, in consultation with its Masters, to reach a realistic and informeddecision without specialised training themselves which receives no mention. If retained,

this wording could also potentially lead to different training being required when an officer

moved from one ship to another, even in the same fleet, depending on the individual Master!A less than satisfactory solution, and very ship specific rather than generic.

Training DeliveryThere is also the matter of the delivery of the training; training leading to issue of a TankerEndorsement must be carried out in accordance with the requirements of STCW which

includes recommendations on the qualifications and experience of instructors; this type of

training must be approved by the flag state issuing the seafarers qualifications, so in the UK

this is the MCA.The draft IGF suggested that training should be carried out by: suppliers of equipment or

other specialists with in-depth knowledge of the gas in question and the technical gas

systems that are in use on board(IMO, 2009)This would presuppose repeat training every time a new or different system was encountered,

and equipment suppliers with competent training departments. There is no mention of

assessment.

Training: Draft IGF

So, to summarise, the draft IGF left training requirements to the Company and the Master;

one having budgetary constraints as a major influence, the other with little enough timealready. With the best intentions in the world, neither is likely to possess the requisite

experience to make an informed judgement, so I would venture to suggest that a global

solution is required, not a ship-specific one such as the current proposal. Many equipmentsuppliers admit that their training package, should it exist, is concentrated totally on their

own equipment rather than the entirety of an installation, and this may not necessarily

include generic safety training for the product handled.

There is no clearly defined requirement as to breadth or depth of training, nor an identifiedrequirement for assessment.

Training Seafarers Only?As well as training seafarers I believe that there is also a good argument for mandatory

training for operating company superintendents and procurement staff, agents, port personnel

and so on to ensure that errors that may be costly in terms of injury to personnel or damage to

assets can be avoided. I would argue that if a vessel designed to operate on LPG fuel at aminimum temperature of42C was supplied with LNG at 160C the results could be

somewhat more catastrophic than loading 460cSt fuel into a ship designed to run on 180cSt,

or to ISO specification RMK380 rather than RMG380. This will become especially

important as different containment systems having different limitations are developed.

AssessmentI have mentioned assessment several times, and you may askwhy? Most education and

training professionals agree that any teaching and learning experience requires assessment in

order to support the learning, demonstrate that learning has taken place and inform the

development of the process leading to the learning experience. Here are some comments byteaching and learning experts:


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... assessment is an integral component of the teaching and learning system and

...to be effective assessment should be valid, reliable and fair(Wakeford, 2003) Assessment should ... require an active demonstration of the knowledge in question

(Biggs, 2003) Assessment can and should support student learning in a number of ways

(MacDonald, 2008)

Put simply, without assessment how can we be certain that the teaching is effective and that

learning has occurred?

Training: SummaryI was concerned when I first read the IGF Code proposals regarding training as I questioned

whether or not they had definition, transparency, or were robust enough to promote safe

operation. I also felt that there was little evidence of accountability or comparability betweensuppliersin other words the proposal as it stood was unacceptable.

The final decision on this is yet to be taken; one current suggestion is that the IGF code is not

the rightful place for training requirements, rather that these should be in STCW, which Ibelieve is a fair comment. However, if that idea was to be carried, it could well be at least

another two years before any regulation is in place following adoption of the IGF code, and a

lot could happen in the interim period.

OUTCOMES?

Remembering that LNG is viewed by many outside the industry as highly dangerous my fear

is that, without training backed up by adequate and robust regulation and direction, therewill, inevitably, be an incident resulting in loss of life or assets that could easily elicit a

disproportionate political response leading to imposition of unworkable requirements that

totally disregard the standards current in LNG ships. This could even compromise theexisting safety record of LNG ships if decisions are taken by those who are uninformed,

badly informed or have purely political gain as motive. An example of this relates to the

steering gear regulations for tankers that followed the Amoco Cadiz grounding in 1978:

despite the official flag-state enquiry identifying the main cause of the steering gear failurethat led to the incident as incorrect procedures regarding the bolting of hydraulic flanges,

regulations were established for redundancy, alarms and auto-change-over for tanker steering

gears.The first vessel I sailed on that fully complied with the new regulations had such a complex

system that it was easy for a bridge watch-keeper who failed to follow the motor change-over

procedure exactly to end up with no operational steering at all until the duty engineer had

been called to reset and restart the system; a somewhat disconcerting experience whentransiting the Dover Strait.

CONCLUSION: PREVENTION IS BETTER THAN CURE

I believe that all maritime industry professionals have a responsibility to ensure that all ofthose who may be involved in the operation of non-gas ships using gas as fuel in the future

receive appropriate, assessed, training; the regulation governing this should will need to startin the IGF code, and should be based on the current proven training required for service on

gas ships, but restricted to the products concerned.

David Cusdin was posthumously awarded the Merchant Navy medal in 2011, partly for

services to marine engineering and partly for his charity work; if economic grounds areallowed to outweigh technical safety in the design, development, and operation of future gas-


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fuelled merchant ships, then when we reflect, in 10 years time, on the use of gas as fuel in

non-gas ships I consider it doubtful that we will be echoing his words regarding a MarineEngineering success story, which will be a sad reflection on the way the technical

management of ship operations and safety has been eclipsed by relatively uninformed

economics.

BIBLIOGRAPHY

Biggs, J. (2003) Teaching for quality learning at university, Open University Press,MaidenheadCampion, A. (2011) Fuel gas on non-gas ships, In: Proceedings of Gastech 2011,

Amsterdam, March 2011

Cusdin, D.R. (1997) The development of liquefied natural gas carriers a marine

engineering success, London, IMarESTIMarEST:MER & Shipping World & Shipbuilder, various editions

IMO (1993) International code for the construction and equipment of ships carrying

liquefied gases in bulk, Second Edition, London, IMOIMO (1996) International standards for training certification & watchkeeping for seafarers

1978 as amended 1995, London, IMO

IMO (2009) MSC.285(86) including draft code on safety for gas fuelled ships, London, IMOMacDonald (2008)Blended learning and online tutoring, Gower, Aldershot

McGuire and White (1986) Liquefied gas handling principles on ships and in terminals,

London, SIGTTO/Witherby

Nautilus International, Telegraph volume 44, edition 11, December 2011Riviera Maritime MediaLNG world shipping, Various editions

Tradewinds shipping news, various editions, including lngunlimited.com

Vaudalon, A. (2000)Liquefied gases marine transportation & storage, London, WitherbyWakeford, R. (2003) In: A handbook for teaching & learning in higher education (Eds: Fry,

H., Ketteridge, S., Marshall, S.,) RoutledgeFalmer, London

Woodward J. & Pitblado R. (2010)LNG risk based safety, Hoboken, Wiley/ AIChE

www.coltoncompany.com

www.dnv.com

www.imo.orgwww.lloydslist.com

www.SIGTTO.org

www.wartsila.com

About the AuthorAlan Campion joined Warsash Maritime Academy as a Senior Lecturer in 2004 where his

specialist area is safe and efficient cargo management on gas tankers. This followed 35 years

working deep sea as a Marine Engineer, starting out as an apprentice on passenger shipsbefore an early move into tankers initially crude oil and products, but later (and for a total

of over 25 years) on to gas ships, both LNG and LPG, much of the time as Chief EngineerOfficer. As well as normal work onboard, he has also spent time in various company

offices involved with docking specifications and new-building projects as well as work on

early ISM initiatives.
http://www.wartsila.com/http://www.wartsila.com/

gas as a fuel for non-gas ships – cause for concern

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