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Modern marine power plants have been designed to improve the overall ship’s efficiency. This pushed the designers of marine machinery to search for unconventional fuels for these plants. During the previous years, diesel oil has been extensively used on-board ships. Due to the high price of light diesel oil and the environmental problems resulting from the use of heavy fuel oil, it has become necessary to search for an alternative to traditional fuels. As a result, natural gas fuel has been used on-board some types of ships, especially short-voyage cruise ships. Unfortunately, there are still some technical and logistic problems related to the use of natural gas as a fuel, especially as it is considered a non-renewable energy source. The use of hydrogen fuel on-board ships, particularly in modern power plants may contribute to overcoming the above problems. The present paper considers the possibility of the use of hydrogen fuel for marine applications and discusses different stages of hydrogen gas cycle beginning with hydrogen generation process from clean energy until using it as fuel for internal combustion engines on-board one RO/RO ship, named Taba, operating in the Mediterranean Sea. Compared to the diesel engine, the hydrogen fuelled engine is found to be lower in thermal efficiency and fuel consumption, however, some adjustments are needed
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Brodogradnja/Shipbilding Volume 66 Number 1, 2015
Ibrahim S. Seddiek,
Mohamed M. Elgohary
Nader R. Ammar
ISSN 0007-215X
eISSN 1845-5859
UDC 629.5.026:662.769.2
Review paper
Modern marine power plants have been designed to improve the overall ship’s
efficiency. This pushed the designers of marine machinery to search for unconventional fuels
for these plants. During the previous years, diesel oil has been extensively used on-board
ships. Due to the high price of light diesel oil and the environmental problems resulting from
the use of heavy fuel oil, it has become necessary to search for an alternative to traditional
fuels. As a result, natural gas fuel has been used on-board some types of ships, especially
short-voyage cruise ships. Unfortunately, there are still some technical and logistic problems
related to the use of natural gas as a fuel, especially as it is considered a non-renewable
energy source. The use of hydrogen fuel on-board ships, particularly in modern power plants
may contribute to overcoming the above problems. The present paper considers the possibility
of the use of hydrogen fuel for marine applications and discusses different stages of hydrogen
gas cycle beginning with hydrogen generation process from clean energy until using it as fuel
for internal combustion engines on-board one RO/RO ship, named Taba, operating in the
Mediterranean Sea. Compared to the diesel engine, the hydrogen fuelled engine is found to be
lower in thermal efficiency and fuel consumption, however, some adjustments are needed.
Key words: alternative fuels; hydrogen engine; hydrogen storage; ship’s emissions
1. Introduction
Marine fuel plays a key role in operation of power plants onboard ships. The latest
years have seen difficult challenges against the use of fossil fuels in marine applications due
to the environmental damage caused by these fuels. That pushed the International Maritime
Organization (IMO) to issue a number of regulations to reduce this effect [1]. Thus, in 2005
the amendments to the Marine Pollution Convention (MARPOL) were issued, i.e. Annex Six
of MARPOL, to reduce air pollution from ships. The requirements of Annex Six establish
limits on ship emissions. Some of these limits concern the permissible percentage of fuel
elements content such as sulphur content [2] while some refer to the percentage of harmful
Ibrahim Seddiek, Mohamed Elgohary, The hydrogen-fuelled internal combustion engine
Nader Ammar for marine applications with a case study
pollutants emitted from ships such as nitrogen oxides [3]. These regulations pressed all
interested in the maritime field to consider potential alternatives to reduce dependence on
fossil fuels [4-6] and search for alternative types of fuels [7]. Thus, many researchers studied
the possibility of using some of alternative fuels, mostly liquefied natural gas [8-10].
Moreover, other researches pointed out the feasibility of using other types of alternative fuels
such as methanol [11] and hydrogen (GH2) [12] for special marine application. On the other
hand, it was shown by Banawan, [13] that the main obstacles facing the reliance on
marine alternative fuels are: availability, cost, reliability, safety and the compliance with IMO
regulations. Among alternative fuels, hydrogen is considered to be more environmental
friendly and renewable. Despite the safety risks of using hydrogen gas onboard ships, several
researches proved the possibility of using it especially for power generation produced by fuel
cells [14]. The problem arising now is searching for marine alternative fuels that can be
produced through clean energy in order to prevent any further environmental damage caused
by production process. The present paper considers the various steps of using hydrogen as an
alternative marine fuel, including its production, storage, fuel system, and finally its
application in internal combustion engines which represent more than 95% of marine power
plants onboard ships. Also, the paper presents a brief introduction to solving the first step of
calculations in the problem of Hydrogen Internal Combustion Engines (HICE) designing. A
computer model, Engineering Equation Solver (EES) software [15], is used in solving the
problem of designing the marine hydrogen engine. Hydrogen gas turbine design can be
benefited by using the advantages of the computer programs; which was illustrated in authors
previous work [16-17].
2. Hydrogen production
Hydrogen can be produced from a number of sources both renewable and non-
renewable by various processes. At present, a large amount of hydrogen is produced by
reforming of hydrocarbons. However, in order to minimize the reliance on conventional fuels,
considerable developments in other GH2 production technologies from renewable resources
have been made [18]. The following sections give a short description of hydrogen production
methods with emphasis on hydrogen production from clean energy sources.
2.1 Hydrogen from fossil fuels
This method depends on converting the hydrogen-containing materials derived from
fossil fuels into a hydrogen-rich gas. Fuel processing of methane is considered to be the most
common commercial hydrogen production technology today. By this method hydrogen gas
can be produced through three basic technologies: partial oxidation, auto thermal reforming
and steam reforming [19]. A major drawback of these technologies is that they produce a
huge amount of carbon monoxide (CO). Consequently, additional steps to remove CO are
needed. The process of production follows the following equations:
CH4 + H2O + heat
CO + 3H2 (1)
CO + H2O
CO2 + H2 + heat (2)
The hydrogen-fueled internal combustion Ibrahim Seddiek, Mohamed Elgohary,
engines for marine applications with case study Nader Ammar
2.2 Hydrogen from renewable sources
Hydrogen could be also produced by other methods than reforming of fossil fuels,
including biomass, pyrolysis, aqueous phase reforming, water electrolysis, photoelectrolysis,
and thermochemical water splitting [20].
2.2.1 Hydrogen from solar energy
Solar energy can be used as a source of energy to achieve hydrogen production
through water electrolysis, photoelectrolysis, and thermochemical water splitting process [21].
Choice of solar energy for this purpose is the matter of environmental effect [22]. Among the
previously mentioned technologies, the solar thermo chemical process is better from the
viewpoint of production rate and environmental effect. For example, in traditional thermo-
chemical technology, fossil fuels are combusted with air, which emits not only green house
gases but also gases that contribute on the ozone layer depletion and acid rains. On the other
hand, the solar thermo chemical technology offers either zero or low hazardous gas emissions
As the main purpose of the present research is searching for environmental friendly
marine fuel, the emphasis of the paper is on the production of hydrogen using solar energy as
renewable source. Figure 1 presents a schematic diagram of solar thermo chemical production
of hydrogen using fossil fuels and water (H2O) as chemical source, including: solar cracking,
solar reforming and gasification.
Figure 1 Clean hydrogen fuel production
Ibrahim Seddiek, Mohamed Elgohary, The hydrogen-fuelled internal combustion engine
Nader Ammar for marine applications with a case study
3. Storage of hydrogen
Hydrogen is an extremely difficult gas to store, this will limit its use until convenient
and cost effective storage technologies can be developed and commercialized. One gram of
hydrogen gas, for instance, occupies about 12 litres of space at atmospheric pressure. In order
to be more convenient, GH2 must be pressurized under a high atmospheric pressure, and
stored in a pressure vessel. In liquid form, hydrogen can only be stored under cryogenic
Only the two major problems pending for solutions may make the full application of
hydrogen fuel not achievable in the near future: hydrogen storage and production cost.
Liquefied hydrogen has a density of 70.1 kg/m3, which is a very small value if compared to
ordinary liquid fuels with densities in the range from 840 to 1010 kg/m3 [24-25], taking into
account that liquid hydrogen heating value is about 3.3 times higher than that for diesel fuel.
The production cost cannot be accurately determined since the hydrogen fuel is not produced
on a mass production basis. Also, for the two major processes of hydrogen extracting, the
water electrolysis and the steam reformation of natural gas; the production process will be
more expensive than the ordinary fossil fuels. The cost of removing carbon dioxide (CO2),
resulting from the natural gas steam reformation, increases the cost of the ‘fossil’ hydrogen
option. Moreover, cost of hydrogen production by electrolysis is about three times higher than
that produced by steam reforming of natural gas.
3.1 Options of hydrogen storage for marine use
Hydrogen storage is considered to be one of the main obstacles against adopting
hydrogen as fuel onboard ships due to its very low energy and due to safety issues [26]. In
this section, storage alternatives, which include compressed gas, liquefied gas and metal
hydrides, are discussed in order to decide which of them will be suitable for marine use. Also,
the transportation is discussed with special reference to the liquefied hydrogen (LH2) carriers
under development.
3.1.1 Compressed hydrogen storage
Compressed hydrogen in hydrogen tanks under pressure of 350 bar to 700 bar is used
for hydrogen tank systems in vehicles [27]. Storing of hydrogen in form of compressed gas is
the simplest storage method. It needs a few devices such as a compressor and a pressure tank.
On the other hand, the drawback of this method is low storage density, which depends on the
storage pressure.
As the storage pressure increase, capital and operating costs will increase. It is
important to know that when compared with traditional fuels, the energy in a compressed
hydrogen tank is very low for the same tank volume density. Regarding the economics of this
type of storage, both capital and operating costs must be well studied.
The hydrogen-fueled internal combustion Ibrahim Seddiek, Mohamed Elgohary,
engines for marine applications with case study Nader Ammar
3.1.2 Liquefied hydrogen storage
Liquefied hydrogen storage refers to the storage of hydrogen in the liquid state by
cooling of hydrogen vapour to the cryogenic temperatures of –253 °C. In addition, it can be
stored as a constituent in other liquids, such as NaBH4 solutions, rechargeable organic liquids,
or anhydrous ammonia NH3 [28]. By this method, the weight of hydrogen can be increased by
approximately 20 times compared to the compressed form for the same volume [29].
3.1.3 Metal hydride hydrogen storage
Storage of hydrogen in metal hydrides can be achieved through bonding the hydrogen
to the surface of metal. Metal hydride hydrogen storage has the following advantages: high
hydrogen energy density volumetric capacity, low pressures and low temperatures [30]. The
safety of this method is exciting since no leakage is possible if the tank is broken or fractured
due to accidents and hydrogen is not released unless heat is provided to break the bonds with
the metal. Nevertheless, hydrogen absorption using metal hydrides, chemical hydrides and
carbon systems, requires further development and evaluation [31].
There are some factors which play a role when deciding which method of storage
might be adopted, including: the required energy density, the amount to be stored, the desired
storage period, and the acceptable cost limit. By analyzing the three main systems, the
following conclusions can be made: liquid storage large hydrogen quantities can be stored,
long-term storage if permanent cooling is applied, and low electricity costs for liquefaction;
compressed storage small storage quantities, and short storage time; a hydrogen gas tank
that contains a store of energy equivalent to a traditional fuel tank would be more than 3,000
times bigger. Of course, this value varies with the pressure, but as already mentioned, higher
pressure means higher cost [32].
For marine use, where large quantities of fuel in addition to long storage time are
needed, the storage of hydrogen in the liquid state may appear as the best storage form.
Although liquid hydrogen can provide a lot of advantages, its uses may be restricted because
liquefying hydrogen by existing conventional methods consumes a large amount of heat.
Practically, compressed hydrogen storage has short filling time and long storage time, while a
liquid hydrogen tank has short filling time and short storage time. Moreover, during the long
period of storage, to minimize and control the boil-off losses, the permanent cooling using
another medium such as liquid nitrogen is needed, which requires additional costs [33].
4. Hydrogen bunkering process & regulations
The best way of the hydrogen fuel bunkering process will be in the form of liquefied
gas. Liquefied hydrogen (LH2) will be stored in cryogenic tanks at the temperature of 20 K
and the amount of bunker fuel will depend mainly on the ship’s sailing time and engines
specific fuel consumption. Figure 2 shows the principle components of hydrogen fuel
bunkering either onshore or onboard ships. Some other considerations should be taken into
account in the fuel amount estimation, such as the expected amount of fuel that has to
evaporate to the gas form during consumption of LH2 to maintain the tank temperature [29].
Ibrahim Seddiek, Mohamed Elgohary, The hydrogen-fuelled internal combustion engine
Nader Ammar for marine applications with a case study
Bureau Veritas (BV) Classification Society has developed a comprehensive set of
guidelines for the use of hydrogen fuel onboard commercial ships. The guidelines combine
existing regulations for gas fuelled ships with regulations for terrestrial fuel cell power
systems adapted for the application onboard ships. The guidelines are now being tested on a
number of pilot projects, of which the Hydrogen-Powered Hybrid Electric Harbour Tug is a
good example [34]. Bureau Veritas is looking forward to work together with partners within
the industry to further develop the use of clean technologies in shipping [35-36].
Figure 2 Hydrogen fuel bunkering system
5. Hydrogen-fuelled internal combustion engines
The last decade has produced significant advancements in the development of the
hydrogen-fuelled internal combustion engine. The beginning was the use of hydrogen as fuel
for spark ignition engines. However, some problems were encountered related to the issues
such as pre-ignition, knock, NOx control and loss in power density. Therefore, much effort
has been put forth in the development of advanced hydrogen engines with improved power
densities. The hydrogen fuelled internal combustion engine (H2ICE) technology passed
through several stages as follows [37-38]:
i. Pressure-boosted H2ICE: problems of pre-ignition, knock and NOx control are
heightened during boosted operation because boosting pressure increases charge pressure and
ii. Liquid-H2ICE was the second phase of H2ICE development where the primary
benefit is the higher stored-energy density of hydrogen available with liquefaction. Moreover,
the charge-cooling effect of the cold hydrogen provides for several advantages compared to
conventional gaseous port fuel injection. However, practical difficulties of liquid storage
include the energy penalty of liquefaction, evaporation during long-term storage, and the cost
of onboard cryogenic dewars.
iii. Direct-injection hydrogen-fuelled internal combustion engine (DI-H2ICE): the direct
injection H2ICE has long been viewed as one of the most attractive advanced H2ICE options.
Preferential of direct-injection hydrogen is based on: the high volumetric efficiency, and the
The hydrogen-fueled internal combustion Ibrahim Seddiek, Mohamed Elgohary,
engines for marine applications with case study Nader Ammar
potential to avoid pre-ignition. The challenge with DI-H2ICE operation is that in-cylinder
injection requires hydrogen-air mixing in a very short time.
iv. H2ICE-electric hybrid: A hybrid-electric version of an H2ICE offers the potential for
improved efficiencies and reduced emissions without the need for aftertreatment. In a hybrid
electric system, the ICE operates either in series or parallel with an electric motor.
6. Hydrogen marine power plants
Hydrogen is suggested to be used for the existing diesel engines to minimize the cost
as much as possible. The suggested engine will be operated with hydrogen being directly
injected into the cylinders, as shown in Figure 3. To initiate the combustion process, low
energy sparks will be needed to avoid using amounts of diesel fuel. Fuel pumps and sparks
are to be electronically controlled (camless engines) to ensure the optimum performance at
various operating conditions, as shown in Figure 4.
One of the main problems related to the adoption of hydrogen for internal
combustion engines is the engine knocking that arises due to malfunction of air fuel ratio and
intake temperature.
Figure 3 Schematic engine control systems
Figure 4 Hydrogen fuel system
Ibrahim Seddiek, Mohamed Elgohary, The hydrogen-fuelled internal combustion engine
Nader Ammar for marine applications with a case study
Different propulsion arrangements can be used to propel the ship. One of them is to
use the hydrogen internal combustion engine connected to the propeller via gearbox, and
another one is a modern arrangement generating electricity by alternators to drive electric
motors coupled to the propellers. Each arrangement has its advantages and disadvantages
related to the field of usage. Figures 5 and 6 show these arrangements. Smaller hydrogen
engines will be needed as shown in Figure 6 for operation at part load in harbours and for
manoeuvring purposes, and also for use with auxiliary engines (A/E).
Figure 5 Direct coupling propulsion Figure 6 Hydrogen electric propulsion
Generally, waste heat in exhaust gases, which is mainly high temperature, is very
important because it eliminates the need for exhaust gas boiler, steam may be directly used
onboard ship for heating or for any other process requiring high temperature [39].
Another use of hydrogen is for fuel cells. Huge developments have been achieved in
this sector over the past few years. However, in the marine field it has been used only in the
naval vessels market for auxiliary power generation and for quiet operation of submarines.
Concerning the commercial market, the development achieved so far is not enough to
convince ship owners to use this fine technology product. From all types of fuel cells, only
two types are the candidates for the use onboard. The proton exchange membrane fuel cell
(PEMFC) and the molten carbonate fuel cell (MCFC) fuelled by hydrogen rich fuels like
natural gas or alcohols [40].
A number of ship design firms introduced designs for many ship types working with
fuel cells as an auxiliary power source or for propulsion in hybrid modes [41]. In the marine
sector, several research programs focused on the use of liquid hydrogen onboard ships in
combustion engines or fuel cells. Although the use of hydrogen for marine applications
provides a lot of advantages, especially regarding environmental issues, it is still restricted
due to safety and storage problems.
7. Case study
The case study refers to repowering operation for a RO/RO ship, named Taba,
operating in the Mediterranean Sea. The ship [42] is originally fitted with 2 MaK 9M453
engines with 2700 kW brake power each. Two alternatives were under consideration, either
using pre-mixing of hydrogen and air before entering the combustion chamber or direct
injection of hydrogen into the cylinders after compression. The analysis was done for both 2
The hydrogen-fueled internal combustion Ibrahim Seddiek, Mohamed Elgohary,
engines for marine applications with case study Nader Ammar
and 4 stroke cycles based on the Otto standard cycle. The highest useful compression ratio
(HUCR) for the hydrogen-air mixture is limited to 6 to avoid explosions [43]. The
compression ratio is also limited between 2 and 6; compression ration less than 2 produces a
very high combustion temperature and the values higher than 6 produce unstable combustion.
Figure 7 shows the comparison between diesel and hydrogen fuels and the variation of
combustion temperature at different excess air factor.
Figure 7 Hydrogen and diesel combustion temperature versus excess air factor
There are some points to be clarified concerning the comparison in Figure 7:
i. The efficiency of the hydrogen engine is lower than that of the diesel engine due to
higher cooling water losses in the case of hydrogen. Without all these losses the temperature
of combustion inside the cylinders may reach very high levels that may put the engine in a
critical state. The obtained result is close to the results published in [44] which demonstrated
the ability of achieving efficiency of about 32%.
ii. Due to the higher energy contained in hydrogen, less fuel is used by mass to produce
the same power, but the product of fuel consumption and calorific value in both cases will
yield a lower value in the case of hydrogen and this is due to lower efficiency.
iii. Very low brake mean effective pressure is available in case of hydrogen if compared
with diesel despite the higher turbo charging pressure in the hydrogen engine (in diesel engine
only 3.3 bar turbo charging pressure is used), this is due to the different nature of gaseous fuel
with a very low density.
iv. Due to lower efficiency and lower density of hydrogen fuel, bigger engine
dimensions are needed to produce the same power at the same speed of the diesel engine. It
can be concluded that the hydrogen engine is still in need of a considerable effort in order to
reach the competition phase. However, attempts to use the hydrogen fuelled engine instead of
the diesel fuelled engine must be continued to overcome those obstacles.
Condition (1): Pre-mixing
Temperature = 127OC (at start of compression inside the cylinder) [45]
Pressure = 1 bar (atmospheric),
Compression ratio = 6
Ibrahim Seddiek, Mohamed Elgohary, The hydrogen-fuelled internal combustion engine
Nader Ammar for marine applications with a case study
Figure 8 shows that at the excess air factor for the bore of 4-stroke exceeds the bore of
2-stroke engines by percentage of 25%. The 2 stroke cycle gives fewer diameters; however,
this is larger by 6cm than the installed engine bore of 32 cm. Figure 9 explains the relation
between brake specific fuel consumption at different excess air factor.
Figure 8 Cylinder bore as calculated for condition (1)
Figure 9 Thermal efficiency and fuel consumption for condition (1)
Condition (2): Direct injection
Temperature = 127OC
Pressure can be varied since no restriction on compression ratio. Figures 10 and 11
illustrate the variation of engine bore at different compression ratio for different pressures for
the 4-stroke and 2-stroke engine respectively.
The hydrogen-fueled internal combustion Ibrahim Seddiek, Mohamed Elgohary,
engines for marine applications with case study Nader Ammar
Figure 10 Bore diameter for Condition 2 (4 strokes)
Figure 11 Bore diameter for condition 2 (2 strokes)
The required diameter can be achieved with a reasonable supercharging pressure. Thus,
direct injection with 2-stroke cycle is the best choice for the engine design. From Figure 12 is
evident that for obtaining the required diameter, a pressure ratio of 9 with supercharging
pressure of 3.7 bar is adopted.
Figure 12 Thermal efficiency and fuel consumption for direct injection condition
Ibrahim Seddiek, Mohamed Elgohary, The hydrogen-fuelled internal combustion engine
Nader Ammar for marine applications with a case study
The comparison between the engine characteristics of the hydrogen engine and the
ship’s original engine (M32C Diesel Engine) can be summarized as shown in Table 1.
Table 1 Comparison between engine characteristics of hydrogen engine and M32C
diesel engine
Engine speed (r.p.m)
Pressure ratio
Heating value of fuel (MJ/kg)
Bore (cm)
Stroke (cm)
Engine power (kW)
Thermal efficiency (%)
Specific fuel consumption (g/
No. of cylinders
Mean effective pressure (bar)
Compression pressure (bar)
Combustion pressure (bar)
The outcome of the preliminary design calculations reveals that the bore of the engine
piston will be the same for the two engines, but the thermal efficiency of the hydrogen fuel
cycle shows a decline compared to that of the original diesel fuel cycle. On the other hand, the
specific fuel consumption is reduced to 93.46 g/ in case of hydrogen fuel.
The engine flow rates can be summarized as:
Fuel : 93.46 g/ (252 kg/hr)
Cooling water : 67.83 kg/ (183007 kg/hr)
Air : 13 kg/ (35087 kg/hr)
Exhaust : 13.1 kg/ (35339 kg/hr)
Regarding the fuel storage tanks onboard the ship; the volume of the ship fuel tanks
(DMA and DMB) is 706.8 m3. When these tanks are used for LH2, only 90% of this volume
can be filled due to insulations. Thus, volume will be 636.1 m3. The volume of LH2 required
for 8 days voyage (2~3 stops in ports) is 1492 m3. This means that the present volume, for
complete hydrogen power plant, i.e. both the main engines and the generators run on
hydrogen, will be sufficient only for a voyage of 3.4 days. Consequently, the extra volume of
about 950 m3 will be needed. This volume can be deducted from the twine deck area as shown
in Figure 13. As can be seen, two times larger tank space in the ship under consideration is
needed to accommodate the hydrogen fuel for only 8 days rather than 20 days as the ship
originally travels.
This problem will occur only in cases when considering the conversion of existing
ships to run on hydrogen, but new designs should include their own hydrogen tank spaces.
Another solution may be available if new storage techniques are invented to overcome this
problem. New techniques are required to provide fuel storage with appropriate energy density.
The hydrogen-fueled internal combustion Ibrahim Seddiek, Mohamed Elgohary,
engines for marine applications with case study Nader Ammar
Figure 13 Modified hydrogen fuel tanks
8. Conclusion
Several issues must be taken into consideration when trying to adopt a new type of
fuel like hydrogen, especially for marine applications where strict rules and regulations
control the design and manufacture of waterborne vehicles. Safety and storage problems are
the main issues arising when talking about the use of hydrogen as fuel. Combustion of
hydrogen inside internal combustion engines has been, and still is, the subject of numerous
research programmes in many countries. Like in the case of natural gas, one of the main
problems associated with the application of hydrogen in internal combustion engines is engine
knocking; air fuel ratio and intake temperature were found to be the main causes for this
problem and their optimization is a must in order to have a knock free engine.
The present paper discussed the different stages of hydrogen gas cycle beginning
with the production process, from clean energy, until using it as fuel for internal combustion
engines onboard a RO/RO ships, named Taba, operating in the Mediterranean Sea. Compared
to the diesel engine, the hydrogen engine was found to be lower in thermal efficiency, mean
effective pressure and fuel consumption, while the both engines seemed to have the same
value of compression and combustion pressure. In addition, some adjustments are needed
regarding the engine’s dimensions, valves timing and fuel system.
However, regarding the ship’s operation, some problems need to be solved. First of
all, it is necessary to make some modifications for the use of hydrogen onboard ships, like for
instance, the fuel storage capacity, as the fuel tanks of the ship under research are not capable
to accommodate the hydrogen needed. The study has shown the need to increase the volume
of bunkering tanks from 706.8 m3 (heavy and diesel fuel) to 1492 m3 (hydrogen fuel) so that
the vessel can provide the necessary space for the hydrogen storage. The design results may
seem strange to the professional reader and yield to the heavy, big and expensive engine, but
it must not be forgotten that this is a first step. Other refinement procedures will follow and
also prototype experiments have to be made to assess how far the calculations are from the
real world and after that a fine tuning processes will follow. This procedure can also be
applied to different types of power plants.
Ibrahim Seddiek, Mohamed Elgohary, The hydrogen-fuelled internal combustion engine
Nader Ammar for marine applications with a case study
This work was funded by the Deanship of Scientific Research (DSR), King Abdulaziz
University, Jeddah, under grant no. (980-580-D1435). The authors gratefully acknowledge the
DSR for their technical and financial support.
Auxiliary engines
Higher Useful Compression
International Maritime
Brake Thermal Efficiency
Liquefied hydrogen
Carbon Monoxide
Marine Pollution
Engineering Equation Solver
Gas Hydrogen
Particulates Mater
Sulfur- Oxides
Hydrogen Internal
Combustion Engines
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Submitted: 19.10.2014.
Accepted: 11.02.2015.
Ibrahim S. Seddiek,
1-Department of Marine Engineering, Faculty of Maritime Studies, King
Abdulaziz University, Jeddah, Saudi Arabia.
2- Department of Marine Engineering Technology, Arab Academy for Science,
Technology & Maritime Transport, Alexandria, Egypt.
Mohamed M. Elgohary
Department of Marine Engineering, Faculty of Maritime Studies, King Abdulaziz
University, Jeddah, Saudi Arabia.
Nader R. Ammar
Department of Naval Architecture and Marine Engineering, Faculty of
Engineering, Alexandria University, Alexandria, Egypt.
... These fuels do not contain carbon nor sulfur and thus their combustion does not generate carbon emissions (CO 2 , CO, HC, soot), or SO x . Despite the good performance and low emissions of hydrogen, its storage is too complicated to be employed in marine engines [5]. Nevertheless, storage and distribution of ammonia are much easier. ...
... The chemical reactions were treated through additional equations. Given a set of N species and m reactions, Equation (4), the local mass fraction of each species, f k , can be expressed by Equation (5). ...
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Nowadays, the environmental impact of shipping constitutes an important challenge. In order to achieve climate neutrality as soon as possible, an important priority consists of progressing on the decarbonization of marine fuels. Free-carbon fuels, used as single fuel or in a dual-fuel mode, are gaining special interest for marine engines. A dual fuel ammonia-diesel operation is proposed in which ammonia is introduced with the intake air. According to this, the present work analyzes the possibilities of ammonia in marine diesel engines. Several ammonia-diesel proportions were analyzed, and it was found that when the proportion of ammonia is increased, important reductions of carbon dioxide, carbon monoxide, and unburnt hydrocarbons are obtained, but at the expense of increments of oxides of nitrogen (NOx), which are only low when too small or too large proportions of ammonia are employed. In order to reduce NOx too, a second ammonia injection along the expansion stroke is proposed. This measure leads to important NOx reductions.
... Hydrogen fuel can also be used directly in IC engines, but storage problems with low-energy density and safety problems are the main obstacle to adopt hydrogen as a widely used marine fuel (Seediek, Elgohary, and Ammar 2015). Hydrogen can be stored in compressed tanks (pressure between 350 and 700 bars) or in a liquefied state (cooled to cryogenic temperature of −253°C), and a direct injection of hydrogen into IC engine is considered to be the most acceptable option (Ahn et al. 2017). ...
... Hydrogen fuel supply system(Seediek, Elgohary, and Ammar 2015). ...
The maritime industry is becoming increasingly aware of the global environ- mental impact of ships and is being forced, by international legislation, to gradually reduce its emissions. International Maritime Organization conven- tions and energy efficiency standards set challenges to shipping sector, to ship owners and ship designers, and to offer propulsion concepts that will effectively reduce or completely eliminate emission rates and increase energy efficiency with acceptable technological costs and adjustment time. New concepts include environmental-friendly fuels in existing propulsion architecture, hybrid propulsion, and all-electric propulsion architecture with the possible application of renewable energy sources, which are reviewed in this paper. Each concept has advantages and disadvantages regarding adjustment time, implementation cost and energy storage system capacity. One of the main disadvantages for complete replacement of conventional propulsion systems is the limited energy storage capacity of existing storage devices, which would decrease the operational ability of the shipping sector as a cheap transportation solution on the global market. Such problems and unsolved environmental issues regarding the production and recycling of energy storage devices are highlighted in this paper and must be further developed. The main motivation for the paper's work is to offer a detailed review of possible solutions for ship propulsion and to offer direction for further research. This is obtained by applying a literature review method to compare the advantages and disadvantages of each proposed solution. The results are discussed in the last section of the paper with the final conclusion that the internal combustion engines will not be completely replaced in the shipping sector in terms of the next few decades but will be able to use environmental-friendly fuels or fuels without a global carbon footprint. This conclusion is the result of analyzing especially large ocean-going vessels with very strong internal combustion engines. Such high power and energy demand are not very easy to be replaced with alternative energy sources or with all-electric ship solution without decreasing all other advantages of merchant shipping sector. Forecasts of ambitious decarbonization scenarios predict wide usage of carbon-neutral fuels in the late 2030s or mid-2040s and Green House Gases reduction (in the range between 50% and 100%) in 2050, which can be obtained by using enviromental-friendly fuels in existing infrastructure. It is still hard to identify which carbon-neutral fuel will be dominant, but e-ammonia, blue ammonia, bio-methanol, and hydrogen are the most promising carbon-neutral fuels in the decarbonization path.
... Particularly, NO x and SO x are considered especially damaging [1][2][3][4]. In the marine field, even stricter limitations imposed by the IMO (International Maritime Organization) and other organizations regulate emissions from ships [5][6][7][8]. Regarding SO x , the maximum content in the fuels is limited for ships that do not have any post-treatment device. Regarding NO x , IMO establishes even stricter maximum emissions depending on the engine and region. ...
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The present work proposes several modifications to optimize both emissions and consumption in a commercial marine diesel engine. A numerical model was carried out to characterize the emissions and consumption of the engine under several performance parameters. Particularly, five internal modifications were analyzed: water addition; exhaust gas recirculation; and modification of the intake valve closing, overlap timing, and cooling water temperature. It was found that the result on the emissions and consumption presents conflicting criteria, and thus, a multiple-criteria decision-making model was carried out to characterize the most appropriate parameters. In order to analyze a high number of possibilities in a reasonable time, an artificial neural network was developed.
... [8] Bigger engine dimensions are needed to produce the same power at the same speed of the diesel engine, and fuel storage capacity is still a major problem for hydrogen powered ships. [9] Although there are studies that tell us which kind of storage is the best. Solid-state storage systems based on metal hydrides have been recognized as one of the most feasible solutions to store hydrogen in hydrogenpowered systems. ...
... In the marine field, marine engines are relevant sources of particulate matter (PM), NOx, and other undesirable substances such as SOx, CO2, CO, HC, etc. [1][2][3][4][5][6]. Among those substances, NOx and SOx are currently receiving special attention due to the increasingly strict limitations imposed by the IMO (International Maritime Organization) and other organisms [7][8][9][10][11][12][13][14][15][16]. In recent years, the need to reduce NOx emissions led to several measures. ...
The present manuscript describes a computational model employed to characterize the performance and emissions of a commercial marine diesel engine. This model analyzes several pre-injection parameters, such as starting instant, quantity, and duration. The goal is to reduce nitrogen oxides (NOx), as well as its effect on emissions and consumption. Since some of the parameters considered have opposite effects on the results, the present work proposes a MCDM (Multiple-Criteria Decision Making) methodology to determine the most adequate pre-injection configuration. An important issue in MCDM models is the data normalization process. This operation is necessary to convert the available data into a non-dimensional common scale, thus allowing ranking and rating alternatives. It is important to select a suitable normalization technique, and several methods exist in the literature. This work considers five well-known normalization procedures: linear max, linear max-min, linear sum, vector, and logarithmic normalization. As to the solution technique, the study considers three MCDM models: WSM (Weighted Sum Method), WPM (Weighted Product Method) and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution). The linear max, linear sum, vector, and logarithmic normalization procedures brought the same result: -22º CA ATDC pre-injection starting instant, 25% pre-injection quantity and 1-2º CA pre-injection duration. Nevertheless, the linear max min normalization procedure provided a result, which is different from the others and not recommended.
... In the future, energy generation should be renewable. As a potential storage material, hydrogen (H 2 ) is considered to be promising and considerable research has been invested into this matter [2][3][4][5]. Scientists and industry discriminate between different colors of hydrogen depending on the method of production: Green hydrogen, for example, implies that production is (almost) CO 2 -neutral using e.g., bio gas or renewable energies such as wind power; whereas gray hydrogen is produced using fossil fuels such as oil or gas. Turquoise hydrogen implies using methane pyrolysis fueled by renewable energy sources, i.e., it is also considered to be CO 2 -neutral. ...
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In both the private and public sectors, green hydrogen is treated as a promising alternative to fossil energy commodities. However, building up production capacities involves significant carbon production, especially when considering secondary infrastructure, e.g., renewable power sources. The amount of required capacity as well as the carbon production involved is calculated in this article. Using Germany as an example we show that the switch to purely green hydrogen involves significant bow waves in terms of carbon production as well as financial and resource demand. An economic model for an optimal decision is derived and—based on empirical estimates—calibrated. It shows that, even if green hydrogen is a competitive technology in the future, using alternatives like turquoise hydrogen or carbon capture and storage is necessary to significantly reduce or even avoid the mentioned bow waves.
... Important contributors to global pollution are diesel engines, which are efficient machines but emit important levels of particulate matter (PM), NO x , CO 2 , CO, HC, SO x , etc. [1][2][3][4][5]. Between these, NO x and SO x are characteristic of marine diesel engines [6][7][8][9][10]. According to the International Maritime Organization (IMO), NO x and SO x from ships represent 5% and 13% of global NO x and SO x emissions, respectively [11]. ...
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In this work, a numerical model was developed to analyze the performance and emissions of a marine diesel engine, the Wärtsilä 6L 46. This model was validated using experimental measurements and was employed to analyze several pre-injection parameters such as pre-injection rate, duration, and starting instant. The modification of these parameters may lead to opposite effects on consumption and/or emissions of nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC). According to this, the main goal of the present work is to employ a multiple-criteria decision-making (MCDM) approach to characterize the most appropriate injection pattern. Since determining the criteria weights significantly influences the overall result of a MCDM problem, a subjective weighting method was compared with four objective weighting methods: entropy, CRITIC (CRiteria Importance Through Intercriteria Correlation), variance, and standard deviation. The results showed the importance of subjectivism over objectivism in MCDM analyses. The CRITIC, variance, and standard deviation methods assigned more importance to NOx emissions and provided similar results. Nevertheless, the entropy method assigned more importance to consumption and provided a different injection pattern.
... Hydrogen -commonly used to feed the fuel celldoes not appear in a molecular form in nature. The methods of its production, although well-developed technologically, are still rather expensive [5,31]. What is more, hydrogen is an extremely difficult gas to store, which seriously limits further development of hydrogen technologies. ...
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The paper concerns the design analysis of a hybrid gas turbine power plant with a fuel cell (stack). The aim of this work was to find the most favourable variant of the medium capacity (approximately 10 MW) hybrid system. In the article, computational analysis of two variants of such a system was carried out. The analysis made it possible to calculate the capacity, efficiency of both variants and other parameters like the flue gas temperature. The paper shows that such hybrid cycles can theoretically achieve extremely high efficiency over 60%. The most favourable one was selected for further detailed thermodynamic and flow calculations. As part of this calculation, a multi-stage axial compressor, axial turbine, fuel cell (stack) and regenerative heat exchanger were designed. Then an analysis of the profitability of the installation was carried out, which showed that the current state of development of this technology and its cost make the project unprofitable. For several years, however, tendencies of decreasing prices of fuel cells have been observed, which allows the conclusion that hybrid systems will start to be created. This may apply to both stationary and marine applications. Hybrid solutions related to electrical power transmission, including fuel cells, are real and very promising for smaller car ferries and shorter ferry routes.
The discussion around shipping decarbonization has accelerated rapidly in 2020 and 2021. The growing studies on alternative marine fuels based on different criteria are indicative of both the complexities involved in marine fuels evaluation and absence of a consistent framework for assessment of alternative marine fuels from a holistic perspective. There is a recent call for an integrated evaluation model for alternative marine fuels with respect to economic, environmental, and social criteria. In this study, we develop and present a comprehensive and integrated set of sustainability criteria that are relevant for evaluating alternative marine fuels. First, we provide an overview of different alternative marine fuel pathways and assess the current challenges associated with adopting alternative marine fuels. Second, we develop 18 sustainability criteria, identified through the academic and trade literature and validated through a multi-stakeholder participatory approach (based on the input from 70 maritime experts), for a systematic and consistent evaluation of marine fuels. Third, based on an in-depth survey, we evaluate maritime stakeholder perspectives on the importance of sustainability criteria. And finally, we provide a discussion of key policy implications and areas for future studies. Our analysis reveals the current degree of agreement amongst maritime stakeholders in the debate about the importance of multiple, and often conflicting, criteria for evaluating marine fuels; the top five most important criteria are regulatory compliance, life cycle GHG, fuel cost, air pollution, and occupational health and safety. The analysis also looks at the importance ranking of each criterion from the perspective of individual maritime stakeholder groups. These findings provide decision-makers with a platform to understand priorities and interests of maritime stakeholder groups for the choice of marine fuels.
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Shipping is a significant contributor to global greenhouse gas (GHG) and air pollutant emissions. These emissions mainly come from using diesel fuel for power generation. In this paper, the natural gas is proposed as an alternative marine fuel to be used instead of conventional marine diesel oil. Numerical analysis of environmental and economic benefits of the natural gas-diesel dual-fuel engine is carried out. As a case study, a container ship of class A7 owned by Hapag-Lloyd has been investigated. The results show that the proposed dual-fuel engine achieves environmental benefits for reducing carbon dioxide (CO2), nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter (PM), and carbon monoxide (CO) emissions by 20.1%, 85.5%, 98%, 99%, and 55.7% with cost effectiveness of 109, 840, 9864, 27761, and 4307 US$/ton, respectively. The results show that the conversion process to the dual-fuel engine will comply with the current and future IMO regulations regarding air pollutant emissions. On the other hand, using the proposed dual-fuel engine on the container ship will improve the ship energy efficiency index by 29.6 % with annual fuel cost saving of 4.77 million US dollars.
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The low-speed marine diesel engine is the most effective of all the ship propulsion systems. On every ship there is a need for thermal energy besides mechanical power to drive the propeller. It is possible to install a heat exchanger in the exhaust system that makes use of waste heat of the exhaust gasses of the diesel engine. Such a combined mechanical and thermal energy generation is called cogeneration. Modern engines allow the variation of the fuel injection timing and the variation of the exhaust valve timing, which results in a great usage flexibility. In the current work a computer simulation model of a low-speed marine diesel engine is presented. The exhaust gas heat energy available to power a heat exchanger was calculated. The time of the beginning of fuel injection and the time of the opening of the exhaust valve was varied. It was analyzed how these parameters influence the power, the fuel consumption, the engine efficiency, the exhaust gas temperature, the heat energy available in the exhaust gasses, the overall efficiency of the cogeneration system, and the power to heat ratio.
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Hydrogen (H2) is currently used mainly in the chemical industry for the production of ammonia and methanol. Nevertheless, in the near future, hydrogen is expected to become a significant fuel that will largely contribute to the quality of atmospheric air. Hydrogen as a chemical element (H) is the most widespread one on the earth and as molecular dihydrogen (H2) can be obtained from a number of sources both renewable and nonrenewable by various processes. Hydrogen global production has so far been dominated by fossil fuels, with the most signi cant contemporary technologies being the steam reforming of hydrocarbons (e.g., natural gas). Pure hydrogen is also produced by electrolysis of water, an energy demanding process. is work reviews the current technologies used for hydrogen (H2) production from both fossil and renewable biomass resources, including reforming (steam, partial oxidation, autothermal, plasma, and aqueous phase) and pyrolysis. In addition, other methods for generating hydrogen (e.g., electrolysis of water) and purification methods, such as desulfurization and water-gas shift reactions are discussed.
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Increasing amounts of ships exhaust gases emitted worldwide forced the International Maritime Organization to issue some restricted maritime legislation for reducing the adverse environmental impacts arising from such emissions. Consequently, ships emission reduction became one of the technical and economical challenges that facing the ships operators. The present paper addresses the different strategies that can be used to reduce those emissions, especially nitrogen oxides and sulfur oxides. The strategies included: applying reduction technologies onboard, using of alternative fuels, and follows one of fuel saving strategies. Using of selective catalytic reduction and sea water scrubbing appeared as the best reduction technologies onboard ships. Moreover, among the various proposed alternative fuels, natural gas, in its liquid state; has the priority to be used instead of conventional fuels. Applying one of those strategies is the matter of ship type and working area. As a numerical example, the proposed methods were investigated at a high-speed craft operating in the Red Sea area between Egypt and the Kingdom of Saudi Arabia. The results obtained are very satisfactory from the point of view of environment and economic issues, and reflected the importance of applying those strategies.
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High-speed crafts suffer from losing a huge amount of their machinery energy in the form of heat loss with the exhaust gases. This will surely increase the annual operating cost of this type of ships and an adverse effect on the environment. This paper introduces a suggestion that may contribute to overcoming such problems. It presents the possibility of reusing the energy lost by the ships' exhaust gases as heating source for an absorption air condition unit onboard high-speed crafts. As a numerical example; the proposed method was investigated at a high-speed craft operating in Red Sea between Egypt and the Kingdom of Saudi Arabia. The results obtained are very satisfactory. It showed the possibility of providing the required ship's air condition cooling load during sailing and in port. Econo - mically, this will reduce the annual ship's operating cost. Moreover, it will achieve a valuable reduction of ship's emissions.
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The progress of economic globalization, the rapid growth of international trade, and the maritime transportation has played an increasingly significant role in the international supply chain. As a result, worldwide seaports have suffered from a central problem, which appears in the form of massive amounts of fuel consumed and exhaust gas fumes emitted from the ships while berthed. Many ports have taken the necessary precautions to overcome this problem, while others still suffer due to the presence of technical and financial constraints. In this paper, the barriers, interconnection standards, rules, regulations, power sources, and economic and environmental analysis related to ships, shore-side power were studied in efforts to find a solution to overcome his problem. As a case study, this paper investigates the practicability, costs and benefits of switching from onboard ship auxiliary engines to shore-side power connection for high-speed crafts called Alkahera while berthed at the port of Safaga, Egypt. The results provide the national electricity grid concept as the best economical selection with 49.03 percent of annual cost saving. Moreover, environmentally, it could achieve an annual reduction in exhaust gas emissions of CO2, CO, NOx , P.M, and SO2 by 276, 2.32, 18.87, 0.825 and 3.84 tons, respectively.
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The appearance of new alternative fuels for urban fleets has motivated the developing of a new methodology to plan the fuel supply infrastructure required to cover the new demand. The fuel cell hydrogen vehicle has been identified as the alternative with the greatest possibilities in the medium to long term to replace conventional vehicles.
Conference Paper
The shipping industry is today challenged by tighter regulations on efficiency, air pollution and the need to reduce its greenhouse gas emissions. The decarbonisation of the global energy system could be achieved with the use of alternative energy and fuels, and so a widespread switch to the adoption of alternative fuel in shipping could be experienced within the coming decades. Lately, many scenarios of alternative fuels in shipping have been investigated. Among the options of alternative fuels with different propulsion technologies, hydrogen with marine fuel cells (FCs) represent an example of such an alternative fuel. This paper proposes a framework to examine a possible transition path for the use of hydrogen in shipping within the context of decarbonisation of the wider global energy system. The framework is based on a soft- linking the global integrated assessment model (TIAM-UCL) and the shipping model (GloTraM). Initial results from this work-in-progress describe the trajectories of hydrogen prices, the characteristic of the hydrogen fleet and the consequences for shipping CO2 emissions, the hydrogen infrastructure requirements, the use of hydrogen in other sectors, and the consequences for global energy system CO2 emissions.
This paper presents an overview of the principles of hydrogen energy production, storage, and utilization. Hydrogen production will cover a whole array of methods including electrolysis, thermolysis, photolysis, thermochemical cycles, and production from biomass. Hydrogen storage will cover all modes of gaseous, liquid, slush, and metal hydride storage. Hydrogen utilization will focus on a large cross section of applications such as fuel cells and catalytic combustion of hydrogen, to name a few.