Considerations for the Global
Environment in the Latest
Large Container Vessels
KATSUYA UWATOKO* 1
MASAHIKO WATANABE* 1
NOBUHIRO SUZUKI* 1

With the globalization of the economy, the amount of cargo trades in the world has been increasing with eachpassing year. About 80% of the physical distribution in the world is supported by marine transport, namely, ships.
With mounting global interest in environmental problems and higher cargo-carrying capacities, the environmentalloads of ship transport have come to attract considerable attention. Various international rules and regulations onshipping and the environment have been put into effect over the last three decades. Even the ship owners themselves
are increasingly concerned about the environment. This paper introduces the treatment of environmental loads in thespecifications for the state-of-the-art container vessels built by Mitsubishi Heavy Industries, Ltd. (MHI). Backgroundconditions behind the specifications and examples of actual applications of the specifications are presented.
out in the event of accidents at sea such as collisions or
groundings.
The new rule requires the correct arrangement of
any fuel oil tank with a capacity of 600 m3 or more, regardless of the type of ship. To be more specific, therule specifies the distances from the fuel tank to theouter shell at the bottom of the ship and side of the ship.
In the case of a large container vessel (with a fuel oiltank capacity of 5,000 m3 or more), for example, the riskof a fuel oil spill in the worst-case scenario is reduced
by arranging the fuel oil tank two meters away fromthe outer shell of the bottom and one meter away fromFig.1
the outer shell of the side (Fig.1
Fig.1). This rule is applied
to ships contracted for newbuilding on and after August
1, 2007. Large container ships equipped with large output main engines and long endurance need to havelarge-capacity fuel oil tanks commensurate with the fuelconsumption and navigation distance. Some vessels in
the 8,000 TEU class, for example, have fuel oil tankswith capacities as high as 8,000 to 9,000 m3. If such a
vessel was to undergo a worst-case catastrophe, the

1. Introduction
Many ships use diesel engines as their main engines
and run them with a low-quality fuel called "C-oil." These
diesel engines discharge exhaust gas after combustion into
the atmosphere, and thus conceivably have impacts on theatmospheric environment. The ships also conceivably impact the marine environment by discarding waste during
operation and discharging and loading ballast water at
ports to maintain ship stability. Accidents pose anotherthreat of environmental impact on the ocean, as any collision or grounding could lead to an outflow of cargo oil andfuel oil.
Among the various types of ships in service, the cargocarrying capacities of container vessels (vessels built
exclusively to transport containers) are being rapidly expanded to accommodate the rising volume of cargo tradeworldwide. The capacities of the vessels sailing the key
shipping routes connecting North America, Asia, and Europe are unprecedented. The vessels are being built larger
in pursuit of high economic efficiency, and the main engines are being built larger to ensure punctual "weekly
service."
Some of the newer large container vessels are being built
to the specifications shown below, with consideration for
the environment.

Outer shellof the hull
Fuel oil tank
1m(w)

2. Measures for the marine environment(1) Fuel tank arrangement
Ships are controlled by the rules and regulations of
the government agencies from the nations that have ratified the international convention MARPOL(International Convention for the Prevention of Pollution from Ships). A new agreement in the annex to theConvention calls for the arrangement of fuel oil tanks
in safe positions that will prevent fuel oil from flowing

3m(1.5h)B.L
2 m (h)cL

Fig. 1 Required distance from the outer shell of
the fuel oil tank (for vessels with a fuel oiltank capacity of 5000m3 or more)

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 44 No. 3 (Sep. 2007)*1 Kobe Shipyard & Machinery Works

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impact on the environment would be tremendous. MHI
has responded by building its newer container vessels
based on similar fuel oil tank arrangements, in spite of
the new convention now in effect.
(2) Treatment of inboard garbage
A ship produces garbage, residue, sewage, and various other oil-containing liquids as it navigates. Treatmentof oil-containing liquids is set down in annex I of
MARPOL. Ships are only allowed to discharge waterwith oil content concentrations of 15 ppm or less after
treatment with an oily water separator. The separated
oil is burned in an incinerator installed on board the shipor landed. The oily water separator is equipped with ahighly sensitive oil content detector. The incinerator,
meanwhile, is designed in accordance with the provisions set down by a subordinate organization committeeof the International Maritime Organization (IMO). The
temperature within the incinerator must be at a constant or higher value at all times, to cope with emulsions
and other materials with high oil content.
Annex IV of MARPOL also regulates the sewage (living drainage, etc.) produced during voyage not only forcontainer vessels, but for all types of ships at sea. The
regulation requires that a ship be equipped with a sewage treatment unit to break sewage into fragments,
disinfect it, and discharge it at sea at a minimum required distance away from land. To ensure thisrequirement, some of the container vessels built by MHI
are equipped with an exclusive tank designed to temporarily collect living drainage at port or during briefnavigation in shipping routes close to land.
Container vessels can also carry highly combustibleor flammable cargoes packed in containers. If these cargoes are loaded in cargo holds, rainwater or seawater
may come into the hold through gaps between the hatch
covers and trickle down the loaded containers to thebottom of the hold. The liquids in some types of cargo
may contain dangerous components and require careful handling. In general, the rainwater or seawaterflowing down to the bottom of the hold collects in a small
depression located on the hold bottom called a "well."Some ships have a special tank to hold this water. Incoming rainwater and seawater are fed into the tank by
piping and kept in the tank until they can be landed.
This exclusive tank is not a requirement in the rule.
There are ship's owner, however, who request the installation of this tank as an environmental measure.
(3) Painting
If marine organisms such as acorn shells adhere to
the underwater hull, the resulting increase in water
resistance will decrease the ship's speed or push up thefuel consumption. To prevent the adhesion of marineorganisms, a paint containing a toxic component called"organotin" used to be painted on the outer shells of
ships. This practice was called into question in 1986,

when a study revealed the bio-accumulation of organotinin marine organisms. The "International Convention
on the Control of Harmful Anti-Fouling Systems on
Ships" adopted at IMO in 2001 stipulated a complete
phase-out of organotin paints from 2003 up to 2008.
Shipbuilders nowadays often use an organotin-free paintthat prevents adhesion by shedding or melting off thesurfaces on which it is painted. Paint makers have also
developed a polymeric paint that forms extremelysmooth surfaces on which marine organisms find it difficult to adhere.
The ballast tank remains in a corrosive and harshenvironment during operation, with alternate exposure
to seawater and air through loading and unloading.
Ballast tanks used to be coated with a paint containing
a tar epoxy with excellent anticorrosion properties. This
had drawbacks, however, as certain carcinogenic substances within tar threaten the health of painting
workers and can contaminate the marine environment.
A modified epoxy paint without tar is now used instead.
There have also been recent measures to protect thehuman body by reducing the levels of VOCs (volatileorganic compounds) in paints. The regulation targets
an approximately 30% reduction of the VOCs emission
from paints and solvents, relative to the large amounts
emitted in 2000. In some cases, the regulation covers
the spray painting facilities and drying facilities of shipbuilders. New facilities need to be constructed andexisting facilities need to be modified.
(4) Ballast water treatment
Ballast water is seawater loaded in tanks to adjust
the trim condition and draft of a ship. The ballast wateris also used to ensure stability and relax stresses acting
on the hull construction. When cargo is loaded and unloaded at port, the amount of the ballast water needs tobe changed according to the change of the weight distribution of the vessel. As many as 10 billion tons of ballast
water are believed to be moved annually by vessels of
all types. The release and intake of the water at ports
and harbors effectively moves seawater from one partof the sea to another. Marine organisms such as seashells and plankton are moved together with the ballast
water, as well as pathogenic organisms. Adverse effects
on the marine environment are reported. Some organisms, for example, breed in areas where they are moved
and change the ecosystems as a result.
This problem came to be handled internationally inthe early seventies. In 1997, the IMO adopted a set of
guidelines for the control and management of ballast
water to minimize the transfer of harmful aquatic organisms and pathogens. The guidelines call for ballast
water exchange on the ocean to minimize environmental effects. The "International Convention for theControl and Management of Ballast Water and Sediments" adopted in 2004 permits the exchange on the
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Technical Review Vol. 44 No. 3 (Sep. 2007)2

ocean up to 2015, but thereafter calls for the installation of ballast water treatment units on board ships.
The specifications for the treatment units have also been
determined. One specification limits the number of living organisms of 50 micrometer or more in size to a
maximum of ten per cubic meter of ballast water. Treatment units to meet this specification are hurriedly being
developed all around the world.

3. Measures for the atmospheric environment
3.1 Hull forms to reduce the consumption of fuelA ship requires fuel to sail. In hull forms with good
propulsion performance, the same ship speed can beachieved with less horsepower. Hull forms with excellent propulsion performance consume less fuel and arefriendlier to the environment.
The Ship & Ocean Laboratory run by MHI in the
Nagasaki Research & Development Center has been developing excellent hull forms and efficient propellers
since its establishment in 1943. In our earlier work on
developing hull forms, we fashioned paraffin models of
up to about 7 meters in length and tested them by collecting resistance data, etc. in towing tanks of 100
meters or more in length. More recently, the dramatic
improvements in the computation processing of CFD(Computational Fluid Dynamics) have made it possible
to simulate a flow around a complicated hull by calculation. With this ability, engineers are now using CFD torefine the hull forms to optimal levels that can be confirmed with model ships. This has shortened thedevelopment study time, allowing us to study many morehulls and develop better hull forms.
3.2 Exhaust gas during navigation
The emission quantities of nitrogen oxides (NOx) andsulfur oxides (SOx) in exhaust gas are set down for thediesel engines frequently employed for general merchantships, including container vessels. This MARPOL annex VI was adopted in September 1997 at IMO and cameinto effect on May 19, 2005.
The emission quantity of NOx is generally related tothe environment during fuel combustion, hence countermeasures against NOx are taken on the engine side.
The amount of SOx is related to the amount of sulfur
contained in fuel, hence countermeasures against SOx
Fig. 2are taken by using a proper type of fuel (Fig.
2).
(1) Nitrogen oxides: NOx
The target for NOx emission is 30% reduction compared to the emission quantity in 1990. The regulation
value for the general main engines for propulsion is 17
g/kWh. In diesel engines, the emission quantity of NOx
and fuel oil consumption rate are in a trade-off relationship. In engines meeting the NOx regulation value,
countermeasures are generally taken by adjusting thefuel oil injection timing. As a result, the fuel oil consumption rate is said to deteriorate by about 2%

Fig. 2 Main engine for large container vesselcompared with that for engines not meeting the NOx
regulation value. Recently, however, research and development of diesel engine makers has optimized the
combustion chamber profiles, ignition timing, fuel spray,
and so on. This has led to success in meeting the NOx
regulation value while minimizing the deterioration of
the fuel oil consumption rate to about 1.2% comparedwith that for engines not meeting the NOx regulation
value. And with the adoption of electronic control engines in recent years, the range of optimization has been
expanded to the timing of fuel injection into the cylinder,
the amount of injection, injection pressure, etc. Thus,
further reductions in fuel consumption are expected.
To certify that the NOx emission quantity of eachdiesel engine is equal to or less than the regulation value,each parent engine is tested for NOx emission in an engine factory test. The results of the operating
parameters and the replaced principal engine spareparts which affect the NOx emission (e.g., the fuel injection timing and nozzle type) are kept on a ship as arecord according to the form of a register called a "technical file." Conformance with the convention is checkedby confirming that the parameters shown in this technical file agree with the actual units. This is confirmedby two types of surveys, one conducted before a ship is
put in service and one conducted periodically after aship is put in service. The Classification society generally carries out these inspections and issues thecertificates on behalf of the Government of the ship's
flag.
(2) Sulfur oxides: SOx
The regulation governing SOx emissions from the exhaust gas of diesel engines requires the use of fuel oils
with a sulfur content of 4.5% or less. In sea areas where
discharges are more strictly controlled (Baltic Sea andthe North Sea), the regulation limits the sulfur content
to 1.5% or less. Independently from this international
convention, some seas around Europe and California aresubject to additional controls calling for the use of lowsulfur fuels.
Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 44 No. 3 (Sep. 2007)

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Main switchboard
Cable reel (Port)
Land-based
power supply

Cable reel (Starboard)
Land-based
power supply

AC 450V 3

60Hz

ACB

ACB

Transformer

VCB

Transformer

VCB

High-voltage shore
connection panel

Fig. 3 System configuration (In the case of a 440V low-voltage system)

Fig. 4 Cable reel

Most ships take the countermeasure for the SOx control requirements using the low-sulfur fuel mentioned
above. During normal navigation, ships should use fuels with a sulfur content of 4.5% or less. Whennavigating in special designated sea areas or in sea areas with individual control, the fuel used needs to be
switched. The container vessels constructed by MHI
meet the requirements by providing a tank exclusive to
low-sulfur fuels or a fuel-switching device.
3.3 Reduction of exhaust gas during loading/unloading at port
Electric power is even required for the operation ofdeck machinery, the feeding of power to reefer containers, and so on during loading and unloading work at
port. There are now attempts being made to limit theexhaust gas by feeding necessary power from shore toships at port, thereby allowing the vessels to shut down
their main engines and diesel generator engines. The
system is called the "Alternative Marine Power (AMP)
System, or in some cases as "Cold Ironing," because allof the inboard sources of heat are stopped.
Container terminals at the Port of Los Angeles(POLA) and the Port of Long Beach (POLB) on the West
Coast of the United States are developing the AMP system in advance of others, and the system is spreading
to other container terminals. The Port of Los Angeles isspearheading efforts with plans to feed power of 6.6 kV/
60Hz, hence this is the power supply voltage likely tobe adopted as standard for the AMP system. To meetthe requirements of the AMP system, it is generally
necessary to have a cable reel housing a power-feeding
cable from shore to the ship, a high-voltage shore connection panel, a step-down transformer (only for 440 V
low-voltage system ships), a ship/shore power
Figs. 3 and 4).
changeover control panel, and so forth (Figs.
The cable reel for supplying the shore power source
into the ship needs to be installed not on the shoreside, but on the ship, in view of the work time and thestate of the wharf where container cranes traverse. The
installation of cable reels on all ships that may enter
ports equipped with the AMP system will require alarge investment in plants and equipment. Given that
the AMP system is only in service at a few ports, carriers have recently been studying a plan for storing cablereels and high-voltage shore connection panels in mobile containers. There are various merits to loading thistype of container onto ships that call on AMP-equipped
ports. The technique enables flexible reactions in response to changes in shipping routes, for example, andthe selection between starboard berthing and port
berthing at a terminal. In the case of additional installation on a ship in service, the technique can also reduce
the work period required for modification.
A 6.6 kV high-voltage system is gradually being introduced on the larger container vessels being built. Yet
the power supply systems on most container vessels,
including those in service, are 440 V low-voltage systems. To meet the requirements of the AMP system, acontainer vessel with a low-voltage system must be
equipped with a transformer designed to step down thevoltage from 6.6 kV fed to 440 V. The transformer capacity has a large impact on the placement and cost.
MHI has actually loaded AMP Systems onto container
vessels with low-voltage systems after thoroughly studying these matters.

4. Conclusion
Many environmental countermeasures and innovations
have been introduced for ships, especially the large container vessels bearing the brunt of physical distribution
around the world. The regulatory background and trends
are also changing. Concern for the environment on a global scale is heightening. MHI will continue proposing
earth-conscious ships by making good use of its technicalcapabilities while meeting customer needs.

Katsuya Uwatoko

Masahiko Watanabe

Nobuhiro Suzuki

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 44 No. 3 (Sep. 2007)4