569
1 INTRODUCTION
The International Maritime Organization (IMO)
recommended that on1January2013 allconvention
ships (with a capacity equal or above 400) apply
procedures limiting carbon dioxide (CO
2) emissions,
which are included in the previously prepared by
shipownersShipEnergyEfficiencyManagementPlan
(SEEMP).
The main source of carbon dioxide emissions on
ships is the combustion of fuels containing the
elementcarbon.
Theprimarysolutionforreducingcarbondioxide
emissions is the use of carbon‐free or
low‐carbon
fuels.However,thisisverydifficulttoimplement,the
marinefuelsused(Tab.1)containcarbonasthemain
component.TheCO
2 emissionfactor for theamount
offuelburned‐c
Fisalsogiven.
Table1.Carboncontentofmarinefuelsandcarbondioxide
emissionfactor–c
F
________________________________________________
Typeof ReferenceCarbon CO2emission
marinefuelcontent factor‐c
F
(averaged)[kgCO
2/kgoffuel]
________________________________________________
Gasoilor ISO8217,from 0.8744 3.206
distilledfuel DMXtoDMB
MarinedieseloilISO8217,from 0.8594 3.151
RMAtoRMD
Heavyfueloil ISO8217,from 0.8493 3.1144
RMEtoRMK
LPG Propane0.8182 3.000
LPG Butane0.8284 3.030
LNG,CNG, Methane0.7500 2.750
methane
Ammonia
Ammonia 0 0/0.4727*
________________________________________________
*with15%pilotdoseofmarinedieseloil
Another basic method should be applied‐
reducing fuel consumption by the elements of the
shipʹspowersystem.Thiscanbeachievedby:
Analysis of Alternative Configurations of Ship Power
Systems Using Biofuels and Renewable Energy
J
.Herdzik
GdyniaMaritimeUniversity,Gdynia,Poland
ABSTRACT: The requirements to reduce emissions of carbon dioxide and other greenhouse gases from
maritimetransportrequiretakingactionsaimedatincreasingtheoverallefficiencyofthepropulsionsystem,
optimalandrationaluseofelectricityandheat.Takingsuchactionsisnecessaryinordertodemonstrate
the
improvementoftheenergyefficiencyindexofashipinoperationoranalreadyexistingone(EEOIandEEXI),
whichwillallowtoobtaincategoryAorBemissionsforagivenship.Obtainingsimilarenergyefficiencyeffects
isalsopossibleafterswitchingtofuelscontaininglesscarbonin
themoleculeandtheuseofrenewableenergy.
Attemptsaremadetocreatenewconfigurationsofcombinedenergysystemssoastoobtainmaximumbenefits
relatedtotheuseofvariousenergysourcesinordertoensuretheproductionofenergyinquantitiesconsistent
withthecurrentdemandoftheship
intheoperatingcondition.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 17
Number 3
September 2023
DOI:10.12716/1001.17.03.08
570
reducingthedemandformechanicalenergyfrom
theshipʹspropulsionsystem,electricalenergyand
heatenergyreceivers;
use of high‐efficiency energy devices and
maintainingtheirgoodtechnicalconditionduring
operation;
useofwasteenergyrecoverysystems(deepwaste
heatrecoverysystems);
reductionofthe
shipʹsoperatingspeed(however,
it extends the duration of the voyage, additional
costsofshipoperationandcrewcostsarise).
Theenginecrewhasthegreatestnumberofactions
that can be taken to reduce fuel consumption (and
reduce the value of Energy Efficiency Operational
Index– EEOI,or
forexistingships‐EEXI).Examples
of actions it should consider, assess the impact and
take:
selection of the type of fuel supplied directly to
powerdevices.Basically,itwillbethechoiceofthe
cheapestfuel,aslongasitcanbeusedinagiven
areaofthesea.
Theshipownerʹsrecommendations,
whichreducetheshipʹsoperatingcosts(fuelinthis
case),arefollowedfirst.Thisalsooftenleadstoa
reductionincarbondioxideemissions,butthisisa
secondaryeffect;
emergency states of power systems force actions
limitingenergyconsumption.Forthesafetyof
the
shipandthecrew,thisisanemergencysituation,
but from the point of view of the EEOI value, it
maybebeneficial;
energygenerationshouldtakeplaceindevicesthat
are in good technical condition. The type and
number of operating devices should be
appropriate to the energy
demand so that they
workoneconomicloads;
therearemoreandmorecomplexsystemsonships
that have the ability to recover (recycle) waste
energy. This applies mainly to the energy
containedintheexhaustgasesfromthemainand
auxiliary engines, thermal energy obtained as a
result
of cooling the charging air, engine cooling
water and lubricating oils. Waste energy is
recovered in utilization boilers by producing
heating steam and/or power steam for
turbogenerators, power gas turbines are
sometimes used (utilization for diesel exhaust
fumes), technical water is produced (as distillate
fromseawater)inevaporatorsusingfrom
thermal
energyfromenginecoolingsystems,etc.Inhigh‐
powerpowerplants(above40MW),theso‐called
deep utilization of waste heat. A number of
additional problems arise for the engine crew.
Most of the disposal devices can be started only
after the port departure maneuvers (from coastal
waters)
arecompleted,whentheloadsonthemain
engine are stabilized. This requires a number of
additional maintenance activities, for which the
limitedenginecrewmaynothavetime;
if the ship is located in areas with controlled
emission of harmful substances into the
atmosphere from ship engines (ECA areas),
the
requirements allowing the ship to stay in these
zonesmustbemetinthefirstplace,e.g.secondly,
actionsaretaken(providedthattherearetechnical
and time possibilities) related to the recovery of
wasteheat;
commissioning of some systems may take place
after consultations between the captain
and the
chief engineer, e.g. the shipʹs air‐conditioning
system. Due to its energy consumption, they can
only be switched on after obtaining permission.
During the operation of the air‐conditioning
system, a number of rules must be observed to
limittheloadonthissystem,e.g.closingwindows,
portholes
andexternaldoorsontheship;
loadsharingbetweenpower devicesoperatingin
parallel should ensure their proper load, which
will ensure, among others, their minimum total
fuelconsumption.
Generallyspeaking,theenginecrewshouldensure
theoperationofappropriatepowerdevicessupplying
the required amounts of individual types
of energy,
withtheminimumtotalfuelconsumption.Lowerfuel
consumption translates into lower carbon dioxide
emissionsintotheatmosphere.
The basic taskof the shipʹscrew istoreduce the
demand for energy, i.e. to save. This also applies to
activities related to the reduction of hull resistance.
Improper
operation of the rudder (excessive rudder
deflections causing theshiptoyaw)causesnot only
lengtheningoftheshipʹspath,butalsoanincreasein
hull resistance. Only forthisreason,the loadon the
main engine increases, while reducing the speed of
theshipfrom0.5to2
knots.Itiscommontousethe
so‐calledautomaticpilot,butitisworthtakingcareof
itscorrectadjustment.
Inheavilytraffickedseaareas,itwillsometimesbe
necessary to adjust the vesselʹs speed (in order to
reducetheriskofcollisiontraffic)sothatvesselscan
pass,
overtake,letavesselwiththerightofwaypass,
etc. at an appropriate distance, in a manner that is
legibletootherships,incompliancewithsafetyrules.
In doubtful situations, a ship should be called by
radio, as to whose behaviour we have ambiguities,
specify and agree on
a common behaviour. The
smaller the speed and/or road correction is, the less
timewewillloseforadditionalmaneuvers.
Most of theimportant devicesforship safetyare
duplicated (in some cases there are even triple
solutions).Onlyoneofthem,e.g.onlyonehydraulic
pump of the steering gear,
should operate under
normalshipoperationconditions.Thebackupdevice
isturnedoff,butleftinthestandbyposition,withthe
possibility of automatic activation in most cases.
Maintaining the operation of redundant devices
generates additional energy demand without
significantly increasing the level of ship operation
safety.
Inorderto
limittheeffectsofgreenhousegaseson
Earthclimate,forwhichmaritimetransportaccounts
for about 3%, the IMO has set the objective of
reducing carbon dioxide emissions, taking into
accountthetransport effect,byatleast30%by2030
and 70% by 2050 compared to 2008. Taking into
account the
equivalent carbon dioxide emission (as
GHGeffect),thisistobe50%by2050[1].
2 BIOFUELSANDRENEWABLEENERGY
In order to comply with IMO regulations, a
transformation of marine fuels and a wider use of
571
renewable energy sources, primarily wind and solar
energy,mustbecarriedout.
2.1 Biofuels
ItispossibletomeetthelimitslimitingCO
2emissions
by using fuels recognized as biofuels (e.g. FAME,
methanol, ethanol), alternative fuels from sources
otherthancrude oil(e.g.gaseousfuels‐LNG,LPG)
and,aboveall,syntheticfuels(syntheticLNG‐SNG,
ammonia) or acting as excess energy storage
(electrolysisofhydrogen,storageanduseasfuel)and
fuelcells.
OneoftheremediesforreducingCO2emissionsis
the use of biofuels. Although they contain carbon
particles, CO
2 emissions from these sources are not
included in the emissions to the atmosphere. A
comparisonofselectedparametersoffuelsconsidered
asmarinefuelsispresentedinTable2.
Table2.Selectedparametersofalternativemarinefuelsand
biofuels[ownelaboration]
________________________________________________
TypeoffuelDensity Lower Equivalent Equivalent
[kg/m
3
] Heating energy demandper
Value volume year[million
[MJ/kg] capacityto tons]*
HFO=1
________________________________________________
Bio‐diesel880 37.2 1.120 388
Renewablediesel 780 44.1 1.066 327
Fattyacidmethylesters 765 43 1.206 336
Methanol794 22 2.099 656
Ethanol789 28 1.660 515
Ammonia682 18.6 2.890/3.468** 776
Propane493 46.6 1.596/2.075** 310
Methane(LNG,SNG) 460 50 1.594/
2.551** 289
Hydrogen(liquid) 71 1204.303/8.606** 120
________________________________________________
*Tocoverenergydemandformarinetransportcomparedto2020
**Additionalvolumeforthermalinsulation
In2021,petroleumfuelsaccountedfor98%ofthe
consumption of marine fuels in maritime transport.
Themainbenefitforthemarineenvironmentwasthe
introductionoftherequirementtousede‐sulphurised
heavy fuels below the threshold of 0.5% for heavy
fuelsand0.1%fordieselandgasoils.
The
IMOregulationsobligeshipownerstoreduce
the consumption of petroleum fuels by achieving a
reduction in CO
2 equivalent emissions for a specific
transport effect [2]. The process of switching to
alternativefuelsisinevitable,butitraisesanumberof
problems during the transition period. The initial
stage is the use of mixtures of petroleum fuels with
biofuelswithacontentofupto25%.Itis
possibleto
adaptmarineenginesbytheirmanufacturerstoburn
such mixtures. Another solution that allows the
combustionofcrudeoilderivedandalternativefuels
is the construction of dual‐ and tri‐fuel engines, in
whichitispossibletoswitchfromonefueltoanother
duringengineoperation.Dueto
otherparametersof
alternative fuels, it is necessary to build additional
tanksandanadditionalfuelsupplysystemforthem.
Withahighautonomyoftheship(over10days),this
results in an increase in space for additional tanks,
due to the lower density of the fuel, lower calorific
valueofthefuelortheneedforthermalinsulationof
thetanks(Table2).
2.2 Renewableenergyformarinetransport
Thebeginningsofseatransportwerepossiblethanks
to the use of wind energy. However, it is a source
witha number ofdisadvantages inordertousethis
energy
intheformofsails.Itmayblowtooweaklyor
too strongly, as well as from directionsthat make it
impossible to keep the ship on the required course.
Sailingshipssailedonsuchcoursestosuchregionsof
theseaswhereasuitablewindwasexpected,inorder
toreachtheintendeddestinationasaresult,although
itwasnotusuallytheshortestroute.
Currently, attempts are being made to use wind
energyintheformofbuildingappropriatemastsand
sails (Figure 1), which are used in the case of
favourablewinddirections, andthe energyobtained
supports
thetraditionalmechanicalpropulsionofthe
ship,reducingthetotalfuelconsumption.
Figure1. Automatically set rigid sails support the shipʹs
propulsion[3]
Asimilarsolutionistodevelopasailintheformof
a kite, which at the appropriate height uses wind
energytosupportthemainpropulsionoftheship.In
both cases, in order to maintain the shipʹs intended
course,itisnecessarytocorrecttherudderpositionin
ordertolimitthelateraldriftoftheshipʹshull.With
favourablewinddirectionsandaproperlyplacedsail,
theload onthe mainengine (andfuelconsumption)
canbereducedby5‐15%(Figure2).
Figure2. A kite‐sail supports the main propulsion of the
ship[4]
Another proposal is a device mounted on the
shipʹs bow or along the shipʹs sides. The Rotor Sail
solutionconsistsofa tallcylindermadeofglassand
carbonfibre,which rotatesaround itsaxisthanks to
an electric motor driving it. A spinning cylinder
exposedtothewind
createsaliftforceperpendicular
572
to the wind direction based on the Magnus effect
(Figure 3). Typically consisting of two or three
cylinders, the system can be retrofitted to existing
vesselsorintegratedintonewdesigns.Onceinstalled
on theship,the solutioniscompletelymaintenance‐
free. The intelligent system independently monitors
weatherconditionsand
rotatesthemechanisminsuch
a way as to maximize the benefits of its use.
Additionalthrustallowstoincreasetheshipʹsspeed
oratagivenspeedoftheshipallowsforreducingthe
loadonthemainengineanditsfuelconsumption.
Figure3. Norsepower designed and developed Rotor Sail.
Flettnerrotorproducesanadditionalthrust tosupportthe
propulsionsystemoftheship[5]
Theuseofphotovoltaiccellsonsmallvessels,e.g.
boats, catamarans, small yachts, is already quite a
common practice. Especially on vessels with few
people, the demand for electricity is relatively low
(powerbelow 100kW).Anadvantageoussolutionis
theabilitytoaccumulateexcessenergyinbatteriesto
usethis
sourceatnight.Thisisimportantfordevices
such as GMDSS, which are powered by a UPS
anyway, which provide uninterruptible power to
these devices, and at the same time have an
accumulatedsupplyofelectricity.
Shipswithamuchlargercapacityareusedinsea
transport. The power demand
for the main drive
rangesfrom1‐100MWandintherangeof0.1‐10MW
of electric power. It should be noted that the
generationofpoweroftheorderof1MWconsumes
about 200 kg of fuel per hour with the emission of
about 620‐630 kg
of CO2. Production of electricity
from renewable sources (mainly the use of solar
energy in photovoltaic panels is being considered)
will reduce fuel consumption and CO
2 emissions in
proportiontothegivenindicator.
Obtainingan electrical power of 10‐100 kW from
photovoltaic panels is basically possible on every
ship. This requires an appropriate design to place
these panels on the shipʹs superstructures or decks
andtoconnectthemtotheshipʹsenergysystem.
An
exampleofapplicationisshowninFigure4.
One kilowatt of peak nominal power of typical
photovoltaic modules is obtained from 6‐9 m
2
of
surface. In order to estimate the required area of
photovoltaic panels for typical power in real
conditions, a value of 10‐12 m
2
/kW should be
assumed.Toobtainapowerof100kW,theestimated
areaofthepanelsshouldbeabout1000‐1200m
2
.This
may only be achievable for a relatively large ship.
Withashiplengthof150mandawidthof30m,the
areaofthemaindeckwillbeapproximately4,000m
2
.
The panels are set in a position approximately
perpendiculartothedirectionofthesunʹsrays,which
allows them to be arranged in several rows, but so
thattheydonotcovereachother.
Theproblemcanbereversedbyknowingthearea
available for the panels and estimating
the expected
electricpowerfromthesepanels.
Figure4. The use of photovoltaic panels and a kite‐sail to
reducetheshipʹsenergydemand[6]
Severaldifferenttypescanbeusedtoincreasethe
shareofrenewableenergysourcesintheshipʹsenergy
demand.
2.3 Fuelcellsandelectricityformarinetransport
Fuelcellsareagreathopeinmanyfieldsofenergy,
includingthegenerationofenergyfortheneedsofthe
ship.If
renewablesareusedtoproducethehydrogen
fuel,theentireenergychainwillbeclean,providinga
truezero‐emissionfuel.They canproduceelectricity
with greater efficiency than current heat engines.
Thereʹs no combustion involved, as the fuel cell
converts fuel directly to electricity and heat. Several
fuel
celltechnologieshavebeendeveloped.Oneofthe
most promising emission‐free technologies is the
protonexchangemembranefuelcell(PEMFC)(Figure
5).
So far, the primary limitation has been the
availablepowerfromfuelcells.Inthepowerrangeof
10‐100 kW, it does not capable of powering ocean
‐
going vessels. ABB has signed a Memorandum of
Understanding with hydrogen specialist Hydrogène
de France (HDF) with the intent to jointly
manufacturemegawatt‐scalefuelcellsystems[7].
Figure5. Theideaofthe working principle of thefuel cell
[7]
573
Obtainingpowerintherangeof1‐10MWmaybe
analternativesolutionforgeneratingenergyonships,
preferring them in order to obtain lower emission
indicators(EEOI,EEXI)frommaritimetransport.The
idea of future marine applications for larger ships
poweredbyfuelcellsisshowninFigure
6.
Figure6.Conceptillustrationofalargevesselpoweredby
fuelcells[8]
The development of ship propulsion leads to the
wider use of modern sources of electricity. A good
exampleis aship builtin2021, poweredby400kW
fuel cells, floating on the Rhône River [6]. It is
estimatedthatitwilltakeabout10‐20yearstoreach
fuelcell
capacities of 10‐50MW,which will provide
theopportunitytocompetewithtraditionalshipboard
heat engines, resulting in their gradual replacement.
The efficiency of heat engines is limited by the
maximum efficiency defined by the Carnot cycle.
Obtaininghigherefficiencyfromfuelcellswillprefer
their use due to
the very high shareoffuel costs in
ship operation. However, there are some issues that
need to be considered and resolved. The main
problem is the source of obtaining new fuels
(methanol, ethanol, and mainly hydrogen) so that
they are considered clean fuels, the production of
whichdoesnotemit
greenhousegases.Anotheristhe
fuelstorageanddistributionsystem,shipbunkering,
the amount of space on the ship occupied by fuel
tankswiththerequiredautonomy ofsailingandthe
totalcostsofthefuelsystem.
3 DUAL‐ORTRI‐FUELMARINEDIESELENGINES
‐ADDITIONALREQUIREMENTSINTHE
DESIGN
ANDOPERATIONOFTHESHIPʹS
ENGINEROOM
Marine dual‐fuel (tri‐fuel) engines are adapted to
work on traditional liquid fuels derived from the
crude oil, and can also operate on gaseous fuels
(mainly LPG, CNG, LNG, SNG). It is necessary to
expand the system of fuel tanks divided
into heavy
fuels, diesel fuels and gaseous fuels. The gas fuel
system is an independent system and requires
additionalprotectionsspecifiedbytheregulationsof
classificationsocieties.Enginesstartonliquidfueland
may run without time limits. Depending on the
vessel’soperatingstate, theenginemay be switched
tothe
secondtypeoffuel.
Therearebasically3modesofoperationfordual
fuelmarineenginesusedon‐boardships:
1. when engine is well supplied with natural gas,
amount of pilot fuel injected is corresponding to
about6%ofthetotalengineload.Inotherwords
majorcontributorto
theengineloadisnaturalgas.
2. when gas supply to the engine is constant and
limited,thenengineissaidtobein“SpecifiedGas
Mode”. Here gas supply is constant, but fuel oil
quantity injected varies to meet changing engine
loaddemand.
3. in “Fuel Oil Only” mode, gas
supply will not be
available, and engine runs only on fuel oil. This
mode is used when engine is unstable, such as
during restricted waters, heavy weather,
manoeuvring,etc.
InternationalAssociationofClassificationSocieties
(IACS)requirefollowingsafetiesindual‐fuelengines
[7]:
useoilfuelonlywhilestarting
theengine;
use oil fuel only during unstable engine
conditions, such as manoeuvring, restricted
waters,etc.;
engine should continue to run on fuel oil even
whengassupplystops;
crankcasereliefvalvestobefittedinwayofeach
crankthrow;
constructionandoperationofpressurerelief
valve
ofengineunitsshouldconsidergasleakinsidethe
engineandsubsequentpressurerise;
exhaust gas system of the engine to be
independentandnot tobemixedwith anyother
systems;
startingairlinetoeachunittobefittedwithflame
arresters;
flame arrester to
be fitted at the inlet of the gas
supplyvalvetotheunits;
apart from automatic shutdown system, gas
supplymustbeabletoshutmanuallyfromengine
startingplatformorothercontrolstations.
4 USEOFRENEWABLEENERGYSOURCESTO
REDUCECO
2EMISSIONSINSHIPOPERATION
Theuseofrenewableenergiessupportingtheenergy
demandby theshipʹspropulsion andenergysystem
improvesitsemissionindexesandmaybeconsidered
asmeetingtherequirementsofenergyefficiencyofa
giventype ofship[2,9‐13].Thismayenablefurther
operation
of the ship and, depending on the
conditionsofusingrenewableenergysources,reduce
the costs of generating energy for the shipʹs needs.
Due to the change in the efficiency of electricity
generation in a generator driven by a diesel engine
depending on its load, there is a situation where
additional energy obtained from renewable sources
doesnotcausealinearchangeinfuelconsumptionby
theengine.Thedifferencesaresosmallthatitcanbe
estimatedthatthisrelationshipislinear.Asaresult,if
3%ofelectricitydemandisgeneratedfromrenewable
sources,itissaidthat
fuelconsumptionandemissions
intotheatmospherehavedecreasedby3%aswell.
Byusingcurrentlyavailabledevicesforgenerating
electricityor thrust(kites,Flettner rotors,sails) from
solar and wind energy, it is possible to reduce the
574
shipʹsenergydemandby1to30%.Onaverage,itis3‐
10%.Inthis case,it is notpossibletomeet the IMO
requirementsforimprovingthetransporteffectofthe
ship.Significantbenefitscanbeobtainedasaresultof
optimizationofseavoyageplanning(useof
available
traveltime),reductionofhullresistance,betteruseof
the shipʹs carrying capacity, shortening of stays on
roadsteads and ports, logistics activities regarding
loadingandunloading,etc.Itisalwaysimportantto
use all optimization possibilities total fuel
consumption, increasing the overall efficiency of the
drive, and even
reducing the demand for energy
(savings). The most important, necessary action,
however, will be the transition to alternative or
carbon‐freefuelstodecarbonisemaritimetransport.
Table 1 presents the CO
2 emission factor for
marine fuels derived from crude oil. Fuels obtained
through synthesis (ammonia, synthetic NG) and
biofuels can be (currently are) considered as fuels
fromwhichCO
2emissionsdonotcounttowardsthe
determined emission factors. In the case of
designating the so‐called equivalent CO
2 emissions
(emissionsofothergreenhousegases,e.g.SOx,NOx,
particulate matter, hydrocarbons from fuel leaks or
misfires in engine cylinders are taken into account),
thisindicatorwillbehigherthanzero,butstillseveral
timessmallerifCO
2emissionsaretakenintoaccount.
In the case of switching from oil‐derived fuels to
biofuels with a share of 50% each or using fuel
mixtures,itmayturnoutthattheshipisabletomeet
theIMOʺFitfor55ʺrequirementstoalimitedextent
untilaround2035.
In2050,theshareofbiofuelswould
havetoreachthethresholdof85%or50%forcarbon‐
freefuels[14].
5 CHANGESINTHECONFIGURATIONOFSHIP
POWERSYSTEMS
The shipʹs energy system is located in a watertight
space called the engine room. In most cases it is
located
at the stern of the ship. In special cases of
certaintypesofships,theyarelocatedintheforepart
(ro‐ro ferries) or amidships (diesel electric engine
roome.g.forpassengerships,cruiseliners).Forlarge
container ships, two independent power plants
separated by a watertight bulkhead and
ships with
dynamic positioning systems, which can have up to
fourindependentpowerplants,werebuilt.Thechoice
ofthetypeof engineroomisalwaysconditionedby
the typeofshipandthe type of cargo carried by it.
Generationofelectricalormechanicalenergy(thrust)
bydevicesusingsolar
energyorwind,arelocatedon
theshipʹsmaindeckoritssuperstructures.Supplying
the generated electricity to the shipʹs main power
system is not a major technical challenge, as is
distributingthe powersupply toall receiversof this
energylocatedindifferentpartsoftheship.
Afterits
production and possible processing (from direct
currenttoalternatingcurrentwithspecificparameters
in the main network), protection of the network
against the risk of short‐circuit, overload, fire,
synchronization with the main network, etc., it was
led through switchboards to power receivers. Apart
fromtheexpansionofthe
powergridwithadditional
elements,thisdoesnotconstituteasignificantchange
inthesolutionsalreadyinuse.
The biggest changes to the fuel system are
necessary for dual‐fuel engines. The gaseous fuel
supplysystemmustbeindependentoftheliquidfuel
fromtheservicetanktothedirect
injectionofgasinto
theintakeduct duringtheintake stroke (four‐stroke
engines)orgasinjectionintothecombustionchamber
(two‐strokeengines).Anexampleofanadditionalgas
supply installation with the required protections is
showninFigure7.
Figure7.Additionalgaseousfuelsystemfordual‐fuelmain
engine
5.1 Analysisofalternativeconfigurationofshippower
systemsforoffshorevessels
Offshore vessels usually operate at a short distance
from land (up to 200 nautical miles) and their
autonomydoesnotexceed30days.Thiscausesships
tohavelimitedfuelreserves.Iftheperiodofstayat
seais
extendedanditisnotpossibletoentertheport
forbunkeringfuel,itispossibletobunkerthematsea
under acceptable weather conditions for such
operations.Onshipsofthistype,dieselde‐sulphured
fueliscommonlyused(theyusuallyworkinspecial
areas), which simplifies the construction
of the fuel
system.Theneedtoreduceemissionfactorsmakesit
necessary to look for solutions that would improve
thissituation.Attemptsaremadetousephotovoltaic
cells, biofuels or mixtures of petroleum fuels and
biofuels(upto25%ofbiofuelcontent,mostoftenitis
possible to operate the
engine without adaptation
changes)andtouseelectricitybatterieschargedfrom
the land grid and fuel cells. The combination of
severalsolutionsallowsforasignificantimprovement
in the emission index, up to the achievement of
category A [9]. This enables the operation of these
shipsinwaters wheremore
stringentenvironmental
protectionregulationshavebeenintroducedoritisa
conditionforsigningacontract.
Figure8. Schematic diagram of the shipʹs power system
with12generatingsetsandthepossibilityofdivisioninto4
mainswitchboards
575
Thepowersystemtypediesel‐electric(D‐E)canbe
very extensive and contain from 4 to 16 generating
sets. In such a case, the main switchboard has the
possibilityofswitchingoffpartofthebusbarsdueto
theirdamage,short‐circuit,floodingofthewatertight
compartment, etc. and
connecting each of the
generatingsetstotwoindependentsections.Figure8
shows a schematic diagram of such a network.
Expansion and protection of the main switchboards
are required, among others, on ships with dynamic
positioningsystems.
5.2 Influenceofmarinefueltypeonaconfigurationof
shippowersystems
Thechoice ofmarinealternativefuel isnecessary by
shipowners, but it carries a high risk. The selection
decision lacks indications from IMO, classification
societiesandconsultingcompanies. Making achoice
has many consequences [15‐18]. One of them was
changing the configuration of the shipʹs energy
system,startingfrom
thefuelstoragetankstothefuel
supply system for the engines. As a result,
shipownersʹactionsareconservative.Theyintroduce
ad hoc changes in order to meet the imposed
requirementswithanindicationoftime,buttheydo
notdecideonsignificantchangesforfearofexcessive
costs that
may be misguided and expose the
shipowner to a financial crisis or bankruptcy of the
company.Therefore,thechangeswillbeevolutionary.
Pro‐environmental solutions will be introduced,
improving emissivity to meet the requirements, but
not going too far, in the expectation that the future
willshowthedirectionofappropriate
changes.
6 CONCLUSIONS
Theconfigurationoftheshipʹsenergysystemismost
influenced by the type of ship and the sailing area.
Theautonomyofswimminghasasignificantimpact
on the solutions of the fuel system and the fuel
supply.Anotherfactor isthe degreeofexpansion of
the energy system using alternative or carbon‐free
fuels. This affects the expansion of the fuel system,
especially in power plants with dual‐ and tri‐fuel
engines. The use of dual‐fuel engines requires
additionalqualificationsoftheenginecrewrelatedto
the process of bunkering gaseous fuels with a flash
point below 60oC (IGF code requirements), its
storage, operation of the gaseous fuel system
supplying the engine and procedures for switching
fromonefueltoanother.
The use of gaseous fuels requires additional
explosion and fire protection, additional ventilation
systemsandtheuseofinertgas.Thetransitiontothe
use of only gaseous fuels will require further
operational experience and raising the reliability
indextothelevelcurrentlyachievedforpowerplants
with conventional fuels. The least changes in the
configurationoftheshipʹs energysystemare caused
by systems using solar or wind energy. They either
work independently
or slightly expand the existing
energy system.Dueto the relatively small power in
relationtotheenergyrequiredbytheship,they can
supporttheenergysystemandimprovetheemission
indicators, but it will not be possible to further
operatetheshiponpetroleumfuels.Inorderto
meet
theʺFit for 55ʺ limits, at least 50% of energy
productionwillhavetousecarbon‐freefuels,andin
thecaseofalternativefuels,theirsharewillhavetobe
around70‐80%.
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