32
LNG
INDUSTRY
SEPTEMBER
2016
It was the need to call at North German city ports, such as
Hamburg and Bremen, that was behind the very first steps down
the road to LNG-powered cruise ships. Carnival Corp.’s Aida
brand wanted new ships that would have the option to burn LNG
as a fuel to generate electrical power while in port. One of the
two new ships of the Aida Hyperion class was delivered in early
2016 and the other is under construction at Mitsubishi Heavy
Industries’ shipyard in Japan. The two ships will not have any LNG
containment systemon board, but each has a main engine
configured to be able to burn LNG as fuel and serve as a power
generator in port.
The 3300-passenger vessels have a typical cruise ship power
plant configuration with four diesel generators capable of
powering two electric propulsionmotors driving twin propellers.
The same engines generate the considerable hotel load of
electrical power needed on a cruise ship of this size. In order to
avoid burning diesel in port, oneMak 12VM46DF main engine
can be switched to burn gas as fuel. This can be supplied from a
barge or truck as LNG or as gas from the city grid. RINAwas
called in to handle the approval and classification aspects of the
new LNG power arrangement.
Moving further
Carnival has ordered four 6600-passenger cruise vessels to
be built by Meyer Werft at its Papenberg (Germany) and Turku
(Finland) yards, and these will use LNG for all normal propulsion
and power generation. For delivery in 2019 and 2020, they will
be built to RINA class and will be not only the first LNG-powered
cruise ships, but also the highest guest capacity cruise ships in the
world, with over 8000 people on board including the crew.
These ships require extensive design work and innovative
solutions tomeet the challenges that will appear as the ships are
developed. RINA’s role is to ensure that the proposed solutions
are safe, and to help assess the risks involved for all parties.
Apart from the LNG fuel, the ships will adopt proven power
plant arrangements with dual-fuel engine generators supplying
electricity for hotel services, as well as the pod-based propulsion
system, which will give the ships a maximum speed above
20 knots and an optimum speed of approximately 17 knots.
The ships are designed for storing LNG on board in Type C
pressurised tanks, and they will use the fuel in their main engines
for all normal operations. The total quantity of LNG stored on
board will bemore than 3000m
3
.
The whole design and all relevant details are developed and
assessed against the latest rules and regulations approved by the
International Maritime Organization (IMO) in June 2015 – the
IGF Code. However, this is the first ever such project, so the rules
inevitably will not cover everything. Where the rules do not
provide prescriptive requirements, the risk assessment approach
is being adopted. For example, risk analysis will be performed for
the evaluation of the following:
LNG fuel containment system.
LNG space ventilation system.
Containment of possible spill during bunkering operation.
Bunker station position.
Gas detector position.
Key issues: bunkering and
training
Bunkering is a key issue. At present design status for a standard
seven-day itinerary, the vessels would need to bunker every
14 days. A solution will be adopted that will allow the vessels to
be bunkered in approximately 6 hours and the LNGwill almost
certainly be supplied by newly-built LNG bunker tankers. Having
a significant number of LNG-powered ships creates buying
power, and Carnival has said that it is seeking to establish LNG
supply in 10 ports in the US, Europe and Asia.
The bunkering time, especially for a passenger ship, is a key
factor in the design of the bunkering systemdesign. Particular
attention will be given to all safety relatedmatters for ensuring a
safe and fast LNG transfer from an LNG bunker tanker to the
ship’s LNG tanks.
RINA is ready to evaluate the different proposals by means of
drawing approval and testing of the proposed solution, including,
where necessary, hydraulic calculations in normal operation and
evaluation of most critical failures and their consequences,
including dangers related to LNG spill and hazardous areas
extension, etc. RINAwill also facilitate dialogue with the involved
flag and port state authorities.
The company is already active in dialogue with the Italian
government on this project and LNG bunkering in general,
helping to define a regulatory background for the authorisations
relevant to themain activities of a LNG bunker chain, such as
onshore storage, shore-to-ship and ship-to-ship (STS) transfer of
LNG.
One big issue for cruise shipowners switching to gas power
is crew training. LNG carriers have an excellent safety record, and
that is because everybody who works on an LNG carrier has
specific training in how to behave on a ship carrying gas.
Basic training will be required for all of the crew on board a
gas-fuelled ship and advanced training will be necessary for
those having to deal directly with LNG handling. Basic training is
important tomake people aware of the differences between a
standard fuel oil and LNG, the possible hazards and the necessary
precautions that everyone should adopt tomaintain the
necessary level of safety. RINA has developed both a basic and
advanced LNG fuel course and is working to get these courses
recognised by the Italian flag administration.
Leading the way in the adoption of LNG as marine fuel is a
big responsibility for the cruise industry, innovative
shipbuilders and energy suppliers involved, as well as for
classification societies, which have to ensure that everything is
done safely.
Figure 1.
3D rendering of the new LNG Costa ships to be built
by Meyer Werft.
