Lopez Mena ferry profile

ferry profile López Mena
High powered
wavepiercer uses
adapted aviation engines
The first application of a
dual-fuel diesel and LNG
gas turbine system on a
fast ferry utilised novel
technology that could be the
start of a whole new type of
high speed propulsion
14 I Passenger Ship Technology I 4th Quarter 2012
ARGENTINIAN owner, Buquebus, is no stranger to innovative
propulsion technology, having employed two gas turbines on
what was formerly the world’s fastest car carrying catamaran,
the 58-knot Luciano Federico L in November 1997. The company’s
need for speed on its River Plate services stems from the
competition with airlines and indeed, during sea trials of
a 55-knot car ferry in 1998, Juan Carlos López Mena, the
company’s president, told a Passenger Ship Technology reporter
that there were no limits to Buquebus’ speed requirement –
except those imposed by technology.
With the firm’s latest newbuild, the 99m wavepiercing
catamaran López Mena (named after the company’s president
himself), it pushed the technology envelope even further by
specifying dual-fuel diesel and liquid natural gas (LNG) gas
turbines to attain a speed of 47 knots. Buquebus’ technical
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The 99m López Mena is the first fast ferry
to employ dual-fuel LNG gas turbines
manager, Anibal Argomedo, commented, “We wanted a very
fast ferry but diesel engines could not give us enough power.
We needed gas turbines to get the power for the high speeds we
required. Furthermore, when we realised that LNG could be less
costly than other fuels today, it allowed us to think about using
LNG-powered gas turbines on a vessel.”
The owner worked with GE Power & Water to adapt GE’s
aviation engines for a maritime application. The LM2500
design which was finalised is an aeroderivative of the TF39
and CF6 GE Aviation high bypass jet engines. They are called
high bypass because the engine powers a large fan that
drives 80 per cent of the air used to generate thrust. As Ivan
Bach, GE’s commercial marine sales manager explained, “Our
GE Aviation engineers removed that fan to create the LM2500
design, using that power to turn a shaft in the rear of the gas
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turbine to provide power for other purposes – in this case for
marine propulsion.”
The two LM2500 engines installed on board López Mena
compress air to over 18 times atmospheric pressure by having
the air pass 16 rows of an axial compressor. The LNG is then
burned in a singular annular combustor using 30 fuel nozzles.
The resulting high pressure, high temperature gas then pushes
through two stages of the high pressure turbine, which is
attached to the axial compressor to provide the power to turn
both assemblies on a common shaft. The gas then travels through
a six-stage power turbine attached to a second, separate shaft that
exits the rear of the turbine to supply mechanical drive power.
According to Mr Bach, “The LM2500 gas turbine has lower
weight than a diesel engine, critical for maximum ship speed. It
is also more reliable, as it has less moving parts. When it is time
Passenger Ship Technology I 4th Quarter 2012 I 15
López Mena
ferry profile
The JCO & Associates-designed interiors are planned to be high quality
for an overhaul the engine can be removed from the package,
and a spare replacement engine installed, while the original
engine goes to an external service depot. There are also lower
structural vibrations and noise than diesel engines.”
The turbines need the fuel to be delivered at a pressure of
23 bar and so required high pressure pumps to be installed.
As LNG is stored in liquid form at a temperature of -161°C,
heat exchangers were also fitted to turn it into a gas, using the
exhaust gas heat. “We needed the fuel to be vaporised to ensure
the engines could go from zero to full power,” commented Mr
Argomedo. Two 200kW Caterpillar C9 gensets are installed to
start the gas turbines, while another four 340kW Caterpillar C18
gensets are utilised for domestic use.
The LM2500 is mounted in an enclosed package that includes
a fuel metering valve, lube oil pump, hydraulic starter motor,
and fire control system. It also has duct work for the air inlet and
exhaust. However, the installation of the propulsion system was
LÓPEZ MENA
Owner
Builder
Designer
Buquebus
Incat Tasmania
Revolution Design
Length, oa
99.00m
Length, wl
90.54m
Beam, oa
26.94m
Draught, design
Deadweight
Speed
Accommodation
Cars
Fuel oil tanks
(main storage)
Fuel oil (generator
header tanks)
LNG tanks (main storage)
Flag
2.98m
450 dwt
47 knots @ 450 tonnes
deadweight, 100% MCR
EQUIPMENT/OUTFIT
1,024 (total passengers and crew)
155
2 x 70,000 litres
Gas turbines
Gensets
Gas turbine gensets
2 x 1,240 litres
2 x 40m3
Uruguay
Class society
Det Norske Veritas
Certification
DNV + lA1 HSLC R4 CAR FERRY
B GAS FUELLED EO
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not entirely straightforward. Robert Clifford, chairman at the
construction yard Incat in Hobart, Australia, reported, “We had
some difficulty getting the engine package completed as we, GE
and the class society involved, Det Norske Veritas (DNV), had to
come to grips with the technical issues involved in this first-of-akind installation. All the issues have now been overcome but the
process took a little longer than we would prefer.”
He continued, “We have learned about the fire control
systems and using oxygen measuring systems to ensure there
are no gas leaks. Monitoring of the atmospheric conditions is
obviously important but fortunately LNG can only be ignited
within a very small range of oxygen and gas mixture. However,
the integration of all these systems has been a little complex.”
Each gas turbine package was inserted through the side of
the ship’s respective hulls using a forklift. Many installation
options were considered by Incat’s sister naval architect
company, Revolution Design, before this approach was decided.
The shaft at the rear of the gas turbine connects to the
gearbox to power the two 22MW Wärtsilä LJX 1720 SR
waterjets. The power turbine can operate at any speed up to
3,600 rpm without any restrictions for critical operating range.
“The waterjets, gearbox and shafts are all bigger than we would
normally fit,” said Mr Clifford.
The propulsion system had to satisfy DNV’s Rules for
High Speed Light Craft, which incorporate requirements for
gas turbine main propulsion and the use of gas fuel. DNV
has much experience with classing LNG-fuelled vessels, as
this particular set of rules was originally developed in 2000.
DNV’s Hobart station manager, Tony Allwood, commented,
Waterjets
Trim control
Hydraulics
Seating
Safety equipment
2 x 22W, GE Power & Water LM2500
4 x 340kW, Caterpillar C18
2 x 200kW, Caterpillar C9
2 x Wärtsilä LJX 1720 SR
Hydraulically operated trim tab
3 x hydraulic power packs
Georg Eknes
4 x 256-people MES, 9 x 128-people
open reversible liferafts
Passenger Ship Technology I 4th Quarter 2012 I 17
ferry profile López Mena
“The amount of rule development as part of this project was
minimal, however there were some alternative safety solutions
proposed by various stakeholders to some design challenges.
Enhanced safety features were commonly incorporated into
these solutions and supported the safety case.”
The location of the two 20m-long cryogenic gas tanks was
one challenge. The gas tanks are double skinned and the gap
between the two skins is pumped to a high degree of vacuum.
Mr Allwood said, “The rules prior to this project did not
allow the tanks to be positioned within the hulls because the
side damage criteria penalises a catamaran design due to the
relatively wide beam and narrow hull compared to monohull
designs, for example. Different tank locations were explored
and finally we agreed to alter the definition of beam for
catamarans so that the side damage criteria were equivalent to
those used for monohulls.”
Mr Clifford commented, “The gas tanks were finally
positioned midships, and the catamaran hulls actually worked
out to be a suitable receptacle for the tanks. They were also
located immediately above the oil tanks which are in the bottom
of the hulls, allowing the oil tanks to be another compartment
removed from the vehicle deck and passenger decks. From a
safety point of view they are in a remote position.”
Revolution Design’s catamaran hulls are a fairly standard
Incat 99m design but are tailored to the calm weather operation
of the River Plate. Mr Argomedo said, “The vessel is designed
above the necessary requirements, to ocean-going vessel
standards.” Each hull is segmented into nine vented watertight
compartments divided by transverse bulkheads. “This is a very
high powered ship but it is still comparatively lightweight,”
said Mr Clifford.
The ship will be refuelled using LNG transported by trucks
to the Buenos Aires terminal from which the vessel will sail.
“We are also looking at liquefying the natural gas found near
the other end of the route in Montevideo, Uruguay,” said Mr
Argomedo. Refuelling should last around an hour. The Buenos
Aires to Montevideo route is around 106nm and should take
López Mena around two hours. Buquebus intends to run two
round trips a day, with possibly a third added in peak season.
Loading over 1,000 passengers and 155 cars should take
about 40 minutes. The vehicle deck is accessed via shore-based
stern ramps across the transom and features nine car lanes.
However, unloading should only last around 15 minutes. The
ship’s design matches the embarkation facilities at Buenos Aires,
but Mr Argomedo reported that Buquebus is installing a new
One of the two gas turbines being slotted into place
through the side of the hull
18 I Passenger Ship Technology I 4th Quarter 2012
Four Caterpillar C18 gensets are for domestic use
passenger ramp in Montevideo.
The accommodation areas were designed by interior
designer Julio Ortega of JCO & Associates. Mr Argomedo
commented, “We have high quality accommodation and use
the best suppliers.” Mr Ortega visited the Incat yard several
times throughout the build to ensure the interiors were to
his liking. Passenger facilities are housed over two decks and
include a children’s room as well as a 1,200m2 duty free shop
which enables passengers to take advantage of the duty free
trade between Uruguay and Argentina. There is also a high
degree of internal LED lighting.
Seating is divided into four classes: VIP, business, first and
economy, each with its own lounge areas and cafeterias. Each
class is fitted out with corresponding classes of Georg Eknes
seats. Crew also have a lounge area. “The onboard facilities
will be of the highest class we have ever built,” commented
Mr Clifford.
Sea trials are imminent, but Mr Clifford reported that
they will be more complicated than those for standard dieselpowered ships. “Normally on a diesel engine ship, a trial
programme will be done in three days but this vessel could take
three weeks. We have to start the engines using diesel and prove
that they work with this fuel. Then we have to introduce LNG
for the first time, which we can only do at 25 per cent load. This
means the ship will have to be at sea at that point.”
Finding enough LNG fuel in Tasmania will also be a
challenge as there is only one LNG truck on the island. “We
will have to refuel in two loads, which could take up to two
days,” said Mr Clifford. The sea trials should be completed
ready for the vessel to be delivered in December and put into
service in January.
Depending on how López Mena performs in operation,
this type of LNG gas turbine-powered vessel could become
popular. “LNG is a very clean fuel and we will consider
using it again. We think it is a very good option,” said Mr
Argomedo. GE’s Mr Bach commented, “As the world requires
better emissions and a cheaper source of fuel, more LNG
fuelled LM2500 gas turbines are sure to be installed in the
next generation of maritime vessels.”
DNV’s Mr Allwood agrees. “Technically there is no reason
why the concept cannot be applied to other high speed ferries,
so we would expect this pioneering design to generate further
interest in the sector.” This could be good news for yards such
as Incat. However, Mr Clifford has a slightly different take on
the technology. “This vessel will act as a demonstrator,” he said.
“We probably will not make any money out of this ship but
the learning curve has been worthwhile. I think there will be
more of this type of ship built with gas turbines or reciprocating
engines, where diesel-type engines can be converted to run on
gas. This is an easier technology to install.” PST
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