Conference Session #A5
Paper #2084
AN OVERVIEW OF DUAL-FUEL, LIQUEFIED-NATURAL-GAS ENGINES
IN MARINE USE: A MORE EFFICIENT ROUTE
Shawn Walls (spw19@pitt.edu), Ian Abrahamsen (ida3@pitt.edu)
Abstract—Throughout this paper, the application,
to utilize the ocean to improve living conditions, not just for
humans, but for the environment as a whole. With this goal
in mind, the Dual-Fuel diesel engine was invented. The
Dual-Fuel engine is a strong, reliable, and eco-friendly
engine that runs on a combination of diesel fuel and natural
gas. Although there are many options for the type of natural
gas to pair with this engine, one of the best choices is
liquefied natural gas (LNG) because of its efficiency and
lack of pollutants. The union of the Dual-Fuel engine and
LNG is not only environmentally beneficial but also
provides economic benefits.
Dual-Fuel engines have
tremendous potential to expose their advantages when
incorporated into the marine transportation industry. Since
nautical vessels in the past have damaged the environment
with diesel engines, there has been a desire to find a more
eco-friendly engine for ships and boats. Because of this
need for greener ships, the Dual-Fuel engine has become a
popular choice for the future of marine transportation.
Through the application of Dual-Fuel engines, private
owners and companies in the nautical business can now feel
more comfortable knowing that they are making the oceans a
cleaner place.
functioning process, and sustainable advantages of DualFuel, Liquefied-Natural-Gas (LNG) engines will be
described and evaluated. Specifically, the engineering
behind these engines in marine use will be analyzed. The
benefits of LNG from societal and ecological standpoints
will also be clearly identified. Natural gas as a liquid saves
substantial
space
during
transportation
and
storage. During its liquefaction, the toxic chemicals in
natural gas are removed. Although natural gas has been
criticized in the past, there are many ecological and societal
benefits from using LNG as a fuel.
With the acceptance of natural gas as a fuel source,
diesel engines can now be modified into Dual-Fuel engines
which run primarily on natural gas with reduced amounts of
diesel fuel. Dual-Fuel engines differ from diesel engines
with the addition of an electronic control unit (ECU) and a
different gas injection system. The ECU regulates the
natural gas injected depending on the amount of diesel gas
added. Dual-Fuel engines produce clean emissions while
maintaining the same power as diesel engines.
Since Dual-Fuel engines are more beneficial and LNG is
transported primarily by ships, mechanical engineers are
regularly trying to incorporate these engines in marine
transportation. Dual-Fuel engines improve nautical
propulsion
technology
without
environmental
damage. Although the Dual-Fuel engine was originally only
used by LNG cargo ships, this engine has become a
prominent technology for the entire boating industry. In
addition to LNG carriers, other vessels will be analyzed as
examples of marine transportation utilizing the Dual-Fuel,
LNG engine.
NATURAL GAS, NOT AS A GAS, BUT AS A LIQUID
Natural gas, as a fossil fuel, is an energy source of limited
quantities across the globe, and like coal and petroleum, the
combustion of natural gas leads to air pollution. Within
these three fossil fuels, natural gas releases the smallest
amount of pollutants, yet natural gas still releases unhealthy
pollutants that need to be controlled. Since 23.5% of the
energy consumed across the world is from natural gas, a
main goal of science and engineering professionals has been
to try and expand the life cycle while decreasing the
environmental concerns associated with natural gas [1]. A
prominent method to reach this desired goal is by liquefying
the natural gas. As a liquid, natural gas becomes a much
more efficient fuel source, for toxins found in natural gas are
not released and it is much easier to store and transport
natural gas in its denser—liquid—form.
Key Words—Dual-Fuel engine, Electronic control unit, Gas
injection system, Liquefied natural gas, LNG Carrier,
Marine transportation
THE EVOLUTION OF THE DUAL-FUEL ENGINE
Over the centuries, mankind has always been curious of the
mighty and mysterious force known as the ocean. More
recently, mankind no longer seeks to rule the ocean, but
rather work with it to make life better for all humanity. The
want to harness the ocean’s qualities all started with ancient
civilizations that built fleets of man-powered ships, to the
industrial revolution that brought forth ships that ran on
steam, to present day where ships are powered by a number
of sources such as electricity, nuclear power, and fossil
fuels. Engineers are constantly searching for the best ways
Going from a Gas to a Liquid
The process of producing LNG requires three primary steps:
retrieval, pretreatment, and liquefaction. The retrieval step
is plainly the act of obtaining the natural gas from its ground
state and transferring it to a natural gas terminal. During the
pretreatment process, undesirable chemicals in natural gas
are removed. Natural gas is a mixture of mostly methane,
ethane, and other compounds which cannot withstand the
University of Pittsburgh
Swanson School of Engineering
April 14, 2012
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Shawn Walls
compression of natural gas into a liquid [1]. Since the
hydrocarbons have lower condensation points than the other
substituents of the mixture, the cooling and pressurizing of
natural gas condenses the excess compounds into liquids
before the hydrocarbons. These dense liquids are then
filtered out of the natural gas, removing water and pollutants
such as carbon dioxide, hydrogen sulfide, and other nitrogen
and sulfur compounds [2]. The LNG becomes more
methane-pure because of this filtration, which is a great
advantage of LNG, because the amount of available methane
is directly related to the amount of energy capable of being
utilized. Because of the filtration of other byproducts, LNG
allows natural gas to be burned with a higher percentage of
methane gas with minimal amounts of pollutants as a result.
After the separation of these chemicals, the Natural Gas
is then fed through dehydration units and a series of cooling
coils in a cryogenic exchanger [3]. Refrigerants are applied
in these units which help liquefy the natural gas. These
refrigerants are “cooler” gases that help condense the natural
gas to its low condensation point of about -265o F [3]. These
refrigerants have even lower condensation points, which
allow the LNG to be extracted from the leftover refrigerant
vapors; these vapors can then also be used again as
refrigerants for other liquefaction systems [3]. The natural
gas is officially a liquid at this stage, and the LNG is fully
prepared to be stored and transported to its required
destination.
shipments, and 200 LNG storage facilities to keep LNG until
necessary [4]. Universally, this is not exactly a tremendous
number, but the amount of LNG facilities and terminals is
increasing every year with no signs of stopping. Inferably,
the steady increase is due to not only the economic and
societal benefits, but the environmental perks as well.
Natural Gas Becomes Greener as a Liquid
As previously stated, upon the liquefaction of natural gas
many of the toxic impurities are filtered out to make the
natural gas more methane-pure. With the gas now being
cleaner, the emissions are much less damaging than ordinary
natural gas. More specifically, LNG releases 20% fewer
emissions than ordinary natural gas and 70% fewer
emissions than the use of coal [1]. Also, if an LNG spill
would occur not much damage could be done. LNG is an
inflammable liquid and it is insoluble in water, which means
it would quickly evaporate requiring no clean-up if an
accidental spill were to occur [4]. Like other fuels, once
LNG becomes a vapor it is flammable, but LNG vapor has a
limited flammability range; LNG vapor needs to be at a
concentration between 5 and 15% mixed with air in order to
ignite [4]. Compared to other fuels, this is a very narrow
range. For example, diesel has a flammability range of 1 to
99% when mixed with air [1]. As mentioned earlier,
liquefied natural gas is becoming a more prominent fuel
source every year. The expected growth rate of LNG has
been estimated to increase by approximately 6.6% every
year for the next twenty years [5]. LNG is also predicted to
make up 50% of the internationally traded gas by 2030,
compared to about 20% in 2004 [5]. To help depict the
increase of LNG, here is a graph from the Natural Gas
Vehicle Industry, showing the recorded and anticipated
international LNG trade from 2000 to 2030.
The Societal and Economic Benefits of LNG
The storage and transportation methods of LNG are the
primary causes of LNG’s economic and societal benefits.
For natural gas to be stored as a liquid, double-insulated
containers are required to keep LNG below its -265o F
boiling point. At this temperature, natural gas is compressed
to 1/615 of its gaseous form in its liquid form [1]. At this
denser state, much more natural gas can be stored at once,
which saves costs and space tremendously. Also LNG is not
stored under pressure, despite the very low temperature
needed, which removes the chance of an inadvertent
explosion. In addition to this safety procedure, natural gas
terminals are equipped with several other precautionary
measures to ensure safety and security such as methane
detectors, personnel and equipment access control, and site
surveillance [4].
In its liquid state, mass amounts of natural gas can be
transported at once. As with the storage, more money can be
saved due to the fact that more natural gas can be transported
at once. Furthermore, with the capability to ship natural gas
at large, areas across the world that previously did not have
much access to natural gas can now obtain it as another
energy source. This is a major societal advantage, because
nations that depend too heavily on a less efficient energy
source now have the opportunity to utilize natural gas.
Across the globe, there currently are 101 import terminals
receiving LNG shipments, 24 export terminals sending LNG
FIGURE 1
PAST AND EXPECTED GROWTH RATE FOR INTERNATIONAL LNG TRADE,
YEAR VS. BILLION CUBIC METERS (BCM). [6]
With fewer emissions released, more space saved, and
transportation costs reduced, LNG is on its way to becoming
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a primary energy source during this century. Still, since it is
a fossil fuel, LNG will not be able to be solely depended on
for all energy requirements. Yet, when compared to other
fossil fuels used today, LNG is a much more efficient fuel,
and will be a great addition to other alternate energy sources
soon-to-be discovered. The Center for Liquefied Natural Gas
welcomes other efficient energy sources to be used in
addition to LNG to help reach a more sustainable world.
Since LNG balances the three aspects of sustainability—
societal aspects, environmental factors, and economic
boundaries—LNG is, by all means, a great, progressive step
to making the natural gas industry more sustainable.
is only another improvement to the engine, making it more
efficient by reducing harmful emissions and costs.
To create a Dual-Fuel engine, certain modifications need
to be made to a diesel engine to allow it to run properly, not
only without error, but also as well as a typical diesel engine.
Luckily, the natural gas and diesel combination reacts quite
similarly in the engine as normal diesel fuel; therefore there
is no added thermal or mechanical stress on the engine.
Without any additional thermal or mechanical stress, the
cooling system does not need to be changed when
transforming the diesel engine to a Dual-Fuel engine [7].
Two integral components of the Dual-Fuel engine that do
have to be added are an electronic control unit and a
redesigned gas injection system. Both of these components
can be augmented as after-market additions.
The electronic control unit determines how the Dual-Fuel
engine’s system functions. It controls how much natural gas
and diesel fuel should be combined in order to maintain
optimal and efficient power. The electronic control unit also
informs the engine when to switch from using both fuels to
solely diesel if necessary [7]. As with using lower-grade
gasoline in engines that require higher-grade, using
inadequate natural gas can cause “knocking” in the engine.
Knocking is the result of auto-ignition, which is an
explosion of the unbalanced gas-air mixture, which can be
heard as a sharp "knocking" sound from the engine [10]. In
the electronic control unit, there are sensors that detect
knocking, the performance of the engine, and both gas levels
in case the engine needs to switch from both fuels to one
fuel. This switch may be needed within the engine in order
to prevent engine damage or poor operation [7]. Overall, the
electronic control unit’s main job is to tell the natural gas
injection system how much natural gas to inject in order to
get the best performance out of the engine as possible.
Other than being powered by natural gas, the engine runs on
the same four-stroke system as a normal diesel engine.
Depicted below is a representation of the four-stroke engine
system from the U.S. Department of Material.
DUAL-FUEL DIESEL ENGINES: THE BASICS
Imagine a strong, efficient, powerful engine that is capable
of hauling large loads for extended periods of time. Now,
imagine a clean, cheap, economical and environmentally
friendly engine that produces next-to-zero emissions. The
Dual-Fuel Diesel Engine acts as a combination of these two
engines, balancing the strength and durability of sturdy
engines plus the eco-friendliness of green engines. Many
people across all fields of work depend on the reliability,
efficiency, and power associated with a typical diesel
engine. At the same time, the world has come to the
realization that there is an overwhelming need to be less
wasteful and more resourceful. With both points of view in
mind, the Dual-Fuel Diesel Engine has the ability to please
everyone. Being the best of both worlds, the Dual-Fuel
engine maintains the same power output of a standard diesel
engine while simultaneously running mainly on natural gas,
providing much less airborne toxins for the environment [7].
With very little cost and hassle, every diesel engine can be
transformed into a Dual-Fuel engine allowing the user to cut
overall costs, produce less waste, and still complete
whatever engine-operated task as quickly and efficiently as
before. A Dual-Fuel engine can be thought of as a diesel
engine with a new eco-friendly twist.
How a Dual-Fuel Engine Works
In order to adequately describe how a Dual-Fuel engine
works, first one must understand how a regular diesel engine
operates. Today’s diesel engine is very similar to the design
that Rudolph Diesel invented over a century ago. It runs on
a four-stroke system: injection, compression, ignition, and
exhaustion [8]. The fuel comes in, the piston compresses the
fuel, the fuel is ignited and forces the piston back down thus
powering the engine, and then finally the waste is released
through the exhaust [9]. The diesel engine has come a long
way from its origin as a two-stroke engine with 4%
efficiency, to the Otto engine, to finally becoming the diesel
engine used today that powers large ocean liners, tractor
trailers, and countless other machines. Following in Otto’s
and Diesel’s footsteps, the creation of the Dual-Fuel engine
FIGURE 2
DIAGRAM OF THE FOUR STROKE CYCLE [11]
With an Improved Fuel, Comes an Improved Engine
As already stated, Dual-Fuel engines produce nearly zero
emissions compared to its predecessor, the diesel engine;
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Power’s Dual-Fuel engines have proven themselves as well;
their engines have covered over 500 million kilometers in
1,700 vehicles [10]. Its use and popularity will only grow
from here and with it will come more research into
improving the Dual-Fuel engine even more than it is now.
Dual-Fuel engines need some form of natural gas to run
which is becoming more and more available as the use of the
engine increases. The natural gas can be obtained from
installing pumps that tap into the pipeline grid [10]. DualFuel’s longevity is preserved in its plethora of uses from
transportation to generating power.
There is already
evidence in this section pointing to the increase of Dual-Fuel
use in marine and land transportation, but Dual-Fuel is also
used in many other areas of energy generation. There are
many power plants that generate power from Dual-Fuel
generators and home appliances like Dual-Fuel ranges and
stoves that contribute to the success of the Dual-Fuel future
[12]. Out of all of Dual-Fuel’s outlets, the use of it in
marine transportation has become one of its most noticeable
applications.
this is because of the fuel that it is being used to power it.
What makes the Dual-Fuel engine so special is that it
produces less carbon emissions, nitrogen oxides, and sulfur
dioxides while remaining equally efficient [12]. The
combination of LNG and the Dual-Fuel engine have
significantly reduced carbon emissions by roughly 15-30%
by having low carbon to hydrogen ration in the fuel. Nitrous
oxides have decreased by 85% due to the “lean burn”
concept, high air to fuel ratios, of the engine. Lastly, DualFuel engines using LNG have almost entirely no sulfur
emissions, for they were eliminated during the liquefaction
process of the natural gas [13] [14].
Ordinarily, natural gas cannot put out the same
compression ratio as diesel because at a certain ratio, the
ignition step is no longer consistently igniting the gas.
However, because Dual-Fuel engines use the diesel fuel as a
type of liquid spark plug, there is no difference in efficiency
and compression ratio [7]. There are a few different types of
natural gas that could be combined with the Dual-Fuel
engine, but the most efficient one is liquefied natural gas.
The main reason LNG is the best choice is because most of
the harmful byproducts that usually go hand-in-hand with
natural gas are eradicated, resulting in fewer emissions when
the Dual-Fuel engine later burns the natural gas.
Within the Dual-Fuel engine, the gas injection system
injects specific amounts of natural gas into the engine to
replace the diesel fuel normally injected. It regulates the
ratio of natural gas to diesel fuel injected into the engine.
Through this regulation, the natural gas and diesel fuel ratio
mimics the expected power output of a classic diesel engine
by keeping the compression ratio the same. The injection
system will reduce the amount of diesel anywhere from 50
to 80%, saving the operator money depending on the
percentage [10]. Another benefit of using LNG is that it
reacts just like diesel would in the engine. LNG is
compressed and ignited; it shoots the piston downward just
as a diesel engine would. The only downside to using a
Dual-Fuel diesel engine with LNG is that the user would
need to keep track of both fuel sources instead of just one
because if the diesel runs out, the engine cannot function.
Although, one would need to be more aware of his or her
machinery, the cost of using primarily liquefied natural gas
will more than make up for the extra attention needed.
GETTING OUR FEET WET
Marine vessels running on pure diesel have been
continuously criticized for the amount of pollution their
engines emit into the air. There have also been disasters
where diesel spills have caused explosions and/or polluted
Earth’s oceans devastatingly. Fortunately, with the
introduction of Dual-Fuel engines, marine vessels can avoid
these risks and make our oceans and atmosphere much
cleaner. As stated earlier, Dual-Fuel engines have much less
emissions than diesel-only engines, and once LNG is
integrated instead of ordinary natural gas, the engine only
gets greener. Because of the several advantages that result
from the combination of LNG and the Dual-Fuel engine, it is
becoming an increasingly popular engine-fuel partnership in
marine transportation.
Dual-Fuel, Prime Choice for LNG Carriers
The first ships to utilize Dual-Fuel engines with LNG were
LNG cargo ships. The main reasoning for LNG carriers to
do this first is simply because they were constantly travelling
to and from LNG import and export terminals. LNG carriers
are quite similar to LNG tanks. They consist of double hulls
with insulation to ensure minimum likelihood of a spill. In
contrast to LNG carriers, most diesel cargo vessels are only
single-hulled, which is an extreme risk, especially with the
dangers associated with diesel spills. In addition to the
double-hulled safety measure, LNG cargo vessels are
equipped with sophisticated leak detection technologies,
emergency shutdown systems, and, as with all modern oil
tankers, radar and positioning systems [4]. In the past 50
years, since the first LNG carrier’s maiden voyage, there has
never been a major incident involved with LNG carriers [1].
Safety is always a primary concern with any technology or
The Future of Dual-Fuel Engines
As with the introduction of any new idea, its reliability,
availability, and longevity are always called into question.
With the perfection of the Dual-Fuel engine, all of these
areas of possible concern have been resolved since it was
first developed. The reliability of the Dual-Fuel engine has
been proven by its continuation of successful demonstrations
in all different aspects of society. This reliability is proven
by the Dual-Fuel engine manufacturing company, Wärtsilä.
Their engines have performed over three million hours of
operation in 470 land and marine vessels [13]. Clean Air
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advancement, and LNG carriers have proven to pay close
attention to this concern and do not show much room for a
tragic accident to happen in the future.
Currently, there are two main types of LNG carriers
transporting the fuel across the seas. These two methods are
spherical-storage tank, and membrane-type carriers. The
LNG-storing spherical tanks—also known as KvaernerMoss Systems—consist of a steel tank cover, insulation, an
aluminum tank shell, an equatorial ring or skirt, a water
ballast tank, and a distribution pipe. [15]. The insulation is
inserted between the steel cover and aluminum shell which
helps keep the LNG at its necessary cool temperature and
gives enough strength to promise no misshaping of the
spherical tank. Due to their spherical shapes, the tanks have
the most mechanical and thermal pressure at the “equator”;
an equatorial ring or skirt is applied here to support the
pressure of the equator, keeping the tanks sturdy and
trustworthy. To keep the tanks stable with the unsteady flow
of the ocean, water ballasts are employed. Lastly, the
distribution pipe connects the series of tanks on the LNG
carrier to help maintain consistent temperatures between all
of the tanks. Also the distribution pipe nearest the engine is
connected to the Dual-Fuel engine itself where it is regasified to supply the carrier with its required fuel. To help
illustrate the spherical storage tank here is an image from Oil
and Gas Journal.
membrane-type LNG carrier, there are many different styles
of membrane styles modified with slight variations. One of
the common styles used today uses a double-membrane,
double-insulation design. A cross-section of this type of
tank is presented below for added clarification.
FIGURE 4
MEMBRANE-TYPE LNG CARRIER CROSS-SECTION
[17]
Over the past fifteen years, spherical-storage tanks have
been more popular for LNG carriers, yet the number of
membrane LNG carriers is steadily increasing. Sphericalstorage carriers were largely used in Japanese shipyards,
making this vessel method very popular. Japan is one of the
most active nations in LNG facilitating 40 of the 101 import
terminals across the globe [4]. Still, due to the flexibility of
membrane-type carriers and the growing interest in LNG,
the number of LNG carriers with membrane systems is
increasing every year.
Although they are so heavily insulated, there is a very
small percentage of LNG that boils into vapor within the
storage of LNG carriers. This is known as Boil-Off Gas
(BOG) and generally ranges between .1 and .15% of the
cargo per day for LNG cargo vessels [15]. With the
application of a Dual-Fuel engine, LNG carriers are able to
use some of this BOG for its own energy needs. The
capability to use BOG is a great advantage of LNG carriers
using Dual-Fuel engines, because it allows the vessel to
consume gas that would otherwise be wasted. Therefore,
along with the other environmental benefits of LNG, DualFuel engines are able to help reduce natural gas waste for
LNG carriers, making them an even more sustainable
innovation.
FIGURE 3
SPHERICAL-STORAGE TANK LNG CARRIER HULL DESIGN [16]
The other main type of LNG carrier, the membrane-type
carrier, has three main components: the membrane, the
insulation, and the ship’s hull. The first and probably most
distinctive part of this method would be the thin flexible
“membrane” which is in direct contact with the LNG cargo
[15]. This membrane typically is about one millimeter thick
and is sandwiched between the contained LNG and the
insulation used to maintain the cold temperature. The cargo
presses upon the membrane as the hull presses the insulation
upon the membrane, reaching a stability point to keep the
LNG properly stored. Although this is the basic design of a
The Expansion of Dual-Fuel and LNG to Other Marine
Vessels
As previously mentioned, one of the best outlets to explore
the maximum potential of Dual-Fuel diesel engines is by
incorporating them into the marine transportation industry.
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Many companies have already made the move to Dual-Fuel
such as TWB, who have designed a Dual-Fuel natural gas
ferry that runs out of Brazil called the “Ivete Sangalo”,
Kawasaki Heavy Industries who have developed a new LNG
cargo carrier to transport much more contained cargo than
the average carrier, and Viking Line who is in the middle of
constructing a cruise liner that will use Dual-Fuel engines
powered by LNG called the “M/S Viking Grace.” [18] [19]
[20]. These are just a few specific examples of the countless
ships that are employing the technology of Dual-Fuel
engines and liquefied natural gas. There are countless
benefits to using this technology such as reduced costs
because of the current price of LNG, reduced weight of the
ship because, when liquefied, LNG has a much higher rate
of energy density, and a lower risk of an oil spill if an
accident would occur, since LNG breaks up so quickly into
the atmosphere when released [21].
The Ivete Sangalo takes advantage of the abundance of
LNG around the El Salvador region and combines it with 4
converted Dual-Fuel diesel engines to run with 70% natural
gas and 30% diesel. The ship contains 20 fuel cylinders that
are able to refuel through natural gas bundles supplied by a
company called CDGN under the commission of BahiaGas,
the local natural gas distributer. The TWB had such success
with Ivete Sangalo that they have commissioned a second
ship to be built [interferry.com] [6]. Kawasaki has designed
a new LNG cargo transport ship to maximize space for
carrying the most amount of LNG at one time. Not only is
the ship significant because of its physical design but also
because it has a new technology called the Kawasaki Panel
System. These panels reduce the rate of LNG evaporation
by strengthening the insulation thus keeping the temperature
inside the containers lower [19].
Finally, the newest addition to the line of LNG Dual-Fuel
ships is Viking’s largest cruise liner, the NB 1376 which was
recently renamed the M/S Viking Grace. It travels from
Stockholm, Sweden to the Aland Islands and Turku, Finland
all on LNG fuel. The design of the M/S Viking Grace is
centered on the use of LNG; they have strategically placed
the fuel tanks outdoors on the stern of the ship in the case
there would be a leak. Even if this were to occur, the gas
would just rise up and evaporate because the gas is lighter
than air. Also while the gas is super cooled, the pipes are
kept at a very low pressure and double-sealed in case there is
a leak, therefore no gas will escape [20]. The creation of the
M/S Viking Grace is part of a much bigger plan organized
by an association known as the Baltic Sea Action Group.
The BSAG is working to clean up the Baltic Sea by
conjoining all levels of society to work for a greener future.
The use of LNG in ships all over the world is reducing the
carbon, nitrous, and sulfur wastes in the atmosphere by
drastic amounts. Viking Line, Kawasaki Heavy Industries,
and TWB are all examples of companies that are leading the
way in salvaging and preserving the future of the world, by
employing LNG to their respective ships.
SAILING INTO A BETTER TOMORROW
With the damaging side effects associated with purely
diesel-operated vessels, it is practically required that a safer
method is utilized more in marine transportation.
Fortunately, with the introduction of the Dual-Fuel engine,
many nautical vessels have been able to divorce from diesel
engines and use a more eco-friendly engine. The relatively
uncomplicated design of Dual-Fuel engines makes the DualFuel engine both ecological and practical. The number of
ships using Dual-Fuel engines is steadily increasing every
year, which is, without question, due to the positive aspects
linked to the leaner engine. In the past, LNG carriers have
been the most common ships to employ Dual-Fuel engines,
but more and more ships are converting to this eangine as
well.
Also, not only are more boats switching to Dual-Fuel
engines, but many of them are applying LNG fuel instead of
regular natural gas. Because of the transformation process
of natural gas to LNG, LNG is able to be burned with fewer
emissions than any other fossil-fuel source. LNG also
allows natural gas to be stored and transported in larger
quantities, which saves money by saving more space. Since
more natural gas can now be shipped as a liquid, natural gas
is becoming more universal. The advantages of LNG are
tremendous additions to the Dual-Fuel engine. Through the
combination of Dual-Fuel engines and the fuel, LNG, the
oceans will become a much cleaner place, providing a much
more promising environment for Earth’s tomorrow.
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[6] J. Seisler. (2009). “L-NGV Growth Anticipated to Follow Dramatic
LNG Market Expansion in Asia and Europe.” Natural Gas Vehicle
Industry. [Online: Web Site] Available: http://www.ngvglobal.com/lngv-growth-anticipated-to-follow-dramatic-lng-market-expansion-in-asiaand-europe-1019
[7] (2010). “How Dual-Fuel works.” Clean Air Power. [Online: Web Site]
Available: http://www.cleanairpower.com/duel-work.php
[8] M. Brain. (2012). “Internal Combustion.” How Stuff Work. [Online:
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[9] T. Benson. (July 11, 2008) “4 Stroke Internal Engine” National
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[10] (2010). “Dual-Fuel FAQs.” Clean Air Power. [Online: Web Site]
Available: http://www.cleanairpower.com/duel-faq.php
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Conference Session #A5
Ian Abrahamsen
Shawn Walls
[11] (2006) “The Aircraft Powerplant.” US Government Material. [Online:
Web Site] Available: http://www.free-online-private-pilot-groundschool.com/aircraft-powerplant.html
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[14] A. Eykerman. (June 12, 2009) “Fuel Flexible Solution Efficient
Shipping.” [Online: Web Site] Aviable:
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sentation_wartsila.pdf
[15] A. Sacchi. (2012). “Types of LNG Carriers.” Pormorsko. [Online:
Web Site] Available: http://www.pomorskodobro.com/en/types-of-lngcarriers.html
[16] A. Finn. (2010). “New FPSO design produce LNG from offshore
sources.” PennWell Corporation. [Online: Web Site] Available:
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[17] (2006). “LNG Carriers: Additional Analysis.” Environmental
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port/MQRA/MQRA%20EIA%20Report%20Appendix%20III.htm
[18] (August 13, 2008). “Dual-Fuel Natural Gas Ferry for Bahia, Brazil.”
NGV Global New [Online: Web Site] Available:
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[19] (2011) “Large LNG-fuelled Container Ship Granted Approval in
Principle.” Det Norske Veritas. [Online: Web Site] Available:
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ershipgrantedapprovalinprinciple.asp
[20] (2011) “Viking Line’s new passenger vessel NB 1376.” Wärtsilä.
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[21] (2010). “LNG Future.” CLNG. [Online: Web Site]
Available: http://www.lngfacts.org/LNG-Future/default.asp
ACKNOWLEDGMENTS
We would like to thank our co-chair, Luby Choi, for
providing us with advice and assistance for our freshman
conference paper. Also, we would like to thank our writing
instructor, Hans Mattingly, for giving us constructive
feedback for our paper.
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