The Maritime Sector and Its Problematic Decarbonization: A Systematic Review of the Contribution of Alternative Fuels

Ci a ion: dos San os, V.A.; Pe ei a da Sil a, P.; Se ano, L.M.V. The Ma i ime Sec o and I s P oblema ic Deca boniza ion: A Sys ema ic Re iew o he Con ibu ion o Al e na i e Fuels. Ene gies 2022,15, 3571. h ps://doi.o g/10.3390/ en15103571 Academic Edi o s: Eugenio Meloni, Albe o-Jesus Pe ea-Mo eno, José Ca los Magalhães Pi es, Ju i Beliko , I a Ridjan Sko , Gio gio Vila di and An onio Zuo o Recei ed: 4 Ap il 2022 Accep ed: 5 May 2022 Published: 13 May 2022 Publishe ’s No e: MDPI s ays neu al wi h ega d o ju isdic ional claims in published maps and ins i u ional a il- ia ions. Copy igh : © 2022 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion (CC BY) license (h ps:// c ea i ecommons.o g/licenses/by/ 4.0/). ene gies Re iew The Ma i ime Sec o and I s P oblema ic Deca boniza ion: A Sys ema ic Re iew o he Con ibu ion o Al e na i e Fuels Vinicius And ade dos San os 1,2 , Pa ícia Pe ei a da Sil a 1,3,4,5,* and Luís Manuel Ven u a Se ano 6,7,* 1 MIT-Po ugal P og amme, Ene gy o Sus ainabili y Ini ia i e (EFS), Depa men o Mechanical Enginee ing, Uni e si y o Coimb a, 3030-194 Coimb a, Po ugal; [email p o ec ed] 2Chemical P ocess Enginee ing and Fo es P oduc s Resea ch Cen e (CIEPQPF), Chemical Enginee ing Depa men , Uni e si y o Coimb a, 3030-790 Coimb a, Po ugal 3Cen e o Business and Economic Resea ch (CeBER), Uni e si y o Coimb a, A Dias da Sil a, 165, 3004-512 Coimb a, Po ugal 4Facul y o Economics, Uni e si y o Coimb a, A Dias da Sil a, 165, 3004-512 Coimb a, Po ugal 5The Ins i u e o Sys ems Enginee ing and Compu e s a Coimb a INESC, Uni e si y o Coimb a, Pólo II, 3030-290 Coimb a, Po ugal 6School o Technology and Managemen , Poly echnic o Lei ia, 2411-901 Lei ia, Po ugal 7Associa ion o De elopmen o Indus ial Ae odynamics (ADAI), Uni e si y o Coimb a, 3030-788 Coimb a, Po ugal *Co espondence: [email p o ec ed] (P.P.d.S.); [email p o ec ed] (L.M.V.S.) Abs ac : The p esen s udy seeks o selec he mos impo an a icles and e iews om he Web o Science da abase ha app oached al e na i e uels owa ds he deca boniza ion o he ma i ime sec o . Th ough a sys ema ic e iew me hodology, a combina ion o keywo ds and manual e ining ound a con ibu ion o 103 wo ks wo ldwide, he Eu opean con inen accoun ing o 57% o all publica ions. Twen y- wo ypes o uels we e ci ed by he au ho s, lique ied na u al gas (LNG), hyd ogen, and biodiesel con ibu ing o 49% o he men ions. G eenhouse gases, sul u oxide, ni ogen oxide, and pa icula e ma e educ ions a e some o he main ad an ages o cleane sou ces i used by he essels. Ne e heless, he e is a lack o p ac ical esea ch on new s anda ds, engine pe o mance, cos , and egula ions om he academy o di ec mo e s akeholde s owa ds low ca bon in ensi y in he shipping sec o . Keywo ds: low ca bon uels; g eenhouse gases; ma i ime anspo a ion; sys ema ic e iew 1. In oduc ion In pas cen u ies he ma i ime sec o has p o ed o be he mos impo an means o anspo o wo ld goods, anspo ing mo e han 1 billion ons o p oduc s by sea wo ldwide, g owing a an a e age a e o 3% pe yea since 1970 [ 1 ]. Al hough sea anspo a ion is he bes indica o o he wo ld economic g ow h, he side e ec has been he impac ega ding he complexi y o deca boniza ion measu es. Nowadays, ma i ime ossil uel consump ion accoun s o a ound 2.2 million ba els o oil equi alen (MBOE), which ep esen s almos 1000 million ons o equi alen ca bon dioxide (M CO 2 eq), e lec ing 3% o global emissions [ 2 ]. Mo eo e , he so-called bunke uel has a e y low quali y, impac ing high emissions o sul u oxide (SOx), ni ogen oxide (NOx), and pa icula e ma e (PM) [3,4]. The Sul u Emission Con ol A eas (SECA) en e ed in o o ce in 2015 o educe he sul u con en om 4.5% o 0.1% in he Bal ic Sea and Ame ican coas and 0.5% elsewhe e in 2020. The NOx emission educ ion egula ions ha e also been in place since 2016 [5]. The demand o low emissions o such compounds igge ed a end owa d cleane uels, as well as he conce ns o e he g eenhouse gases (GHG) emission educ ions, which ha e d awn he a en ion o go e nmen s wo ldwide. Ene gies 2022,15, 3571. h ps://doi.o g/10.3390/en15103571 h ps://www.mdpi.com/jou nal/ene gies Ene gies 2022,15, 3571 2 o 30 Since 2011, he In e na ional Ma i ime O ganiza ion (IMO) has implemen ed a eg- ula o y measu e o ene gy e iciency equi emen s o all ships globally o educe gas emissions om he shipping sec o , h ough p og ams such as he Ene gy E iciency Design Index S anda ds (EEDI) and he Ship Ene gy E iciency Managemen Plan (SEEMP) [ 6 – 9 ]. Howe e , se e al measu es a e s ill needed o achie e he a ge o 50% lowe emissions by 2050 [9]. The In e na ional Ene gy Agency scena io p oposed a numbe o ac i i ies ha mus en e in o o ce immedia ely o mee he expec ed a ge s, which includes he use o al e na i e uels. The e a e cu en ly se e al s udies and esea ch connec ing he ma i ime sec o o low emissions. Ne e heless, only LNG has been widely discussed while o he al e na i es a e ha dly men ioned. The e o e, he sys ema ic e iew eme ges as an impo an me hodology o quan i y he numbe o esea ch, egions, and au ho s ha a e add essing low ca bon op ions o he ma i ime sec o . The sys ema ic e iew me hodology is equen ly used in clinical esea ch and social sciences. Howe e , i has been cons an ly used in o he esea ch ields as well [ 10 – 12 ]. We looked up se e al pape s and e iews in he Web o Science (WoS) da abase wi h speci ic selec ed keywo ds ela ed o low ca bon uels in he ma i ime sec o o unde s and he p oposed esea ch ques ions (RQ) in s a is ical e ms: Wha is he numbe o al e na i e low ca bon uel publica ions? (RQ1); Wha a e he la ges coun y con ibu o s? (RQ2) Who ha e been he mos impo an au ho s? (RQ3); Which jou nal has con ibu ed he mos in numbe o publica ions? (RQ4); and Wha ha e been he mos ci ed al e na i e uels (RQ5). This s udy assesses he main publica ions (a icles and e iews) in he cu en ly a ailable li e a u e on he Web o Science (WoS) da abase o iden i y he mos ele an cleane al e na i e uels as deca boniza ion sou ces in he ma i ime sec o , highligh ing hei ad an ages and disad an ages as well as iden i ying he gaps o o e come in u u e esea ch. Mo eo e , we will make a desc ip i e s a is ical analysis o he selec ed pape o iden i y he mos in luen ial and p oduc i e au ho s, egions, and jou nals ha ha e con ibu ed highly o his ho opic o e ime. The a icle is a anged as ollows. Sec ion 2 p esen s he gene al e iew o essel ypes, cu en uel g ades used, and he emissions conce ns o IMO. Sec ion 3se s ou he me hodology o pe o m he e iew, delinea ing he keywo ds and e ining p ocedu e. Sec ion 4p esen s he analysis execu ed, highligh ing he p oduc ion o e ime, main jou nals, egions, coun ies’ collabo a ions, mos ci ed al e na i e uels as low ca bon op ions, and he ba ie s o be o e come. Sec ion 5p esen s he conclusions, discussion, and sugges ions o he u u e. 2. Gene al Re iew o Vessel Types and Cu en Fuels 2.1. Ca go Ship Classi ica ion and P opulsion Nowadays, a ound 52,000 ca go ships anspo goods ac oss he wo ld. They a e bulk ca ie s, oil anke s, and con aine ships [ 12 ]. Ma ine diesel engines a e undamen ally he same as ha o oad ehicles, ye hey a e commonly bigge and wo k wi h highe e iciency. Abou 75% o all ma ine diesel engines a e ou -s oke; no wi hs anding, 75% o he in oduced powe is deli e ed by wo-s oke engines [ 13 , 14 ]. All o hese ships ep esen 500 GW o engine capaci y [ 12 ], mo e han all ins alled enewable (428 GW) and ossil (365 GW) powe in Eu ope [ 15 ]. In o de o comp ehend he dimension o he shipping sec o which has an exclusi e demand o ossil uels, Figu e 1compa es he di e en sou ces o he Eu opean elec ici y capaci y ( enewable and non enewable) e sus he wo ld ma i ime engine capaci y. Ene gies 2022,15, 3571 3 o 30 Ene gies2022,15,xFORPEERREVIEW3o 31    Figu e1.Wo ldma i imeenginepowe compa ed oEu opeanins alledpowe (The igu ewas cons uc edbasedonda acap u ed omBalcombee .al(2019)[12]andS a is a(2020)[15]. The ea eessen ially h eeca ego ieso ma ineengines:slowspeed,mediumspeed, andhigh‐speed,no mallyclassi iedinkno s(15–25kno s)[12,16].Theca ego ychoice dependson hesize,enginespeed,andpu pose.Mode a espeedengines egula ly unc ionunde 350 e olu ionspe minu e( pm)andha eexcep ionallylow uel u iliza ion.As a assizeisconce ned,slow‐speedenginesa e hela ges engineson he plane  ha usehea y ueloil(HFO) o igni ion[13,17]. 2.2.Ma ineBunke Classi ica ion Ma ine uelcanbeclassi iedasdis illa e,in e media e,and esidual(Table1).The dis illa eclassesa enamedma inegasoil(MGO)o ma inedis illa eoil(MDO)which ha edi e en g ades(DMA,DMB,DMX,DMZ).Thele e s“A”,“B”…“Z”, e e  o he pa icula p ope iesunde  hep oduc speci ica ion,ISO8217:2017[18,19]. Thein e media e ueloil(IFO)isdi idedin og ades180and380, hesenumbe s co espond o hemaximumkinema ic iscosi yo  he esidual uel,insqua emillime e s pe second(mm2/s)a 50°C[19]. Residual uels,alsocalled esidualma ine uels(RMA,RMB,RMD,RME,RMG, RMK)o hea y ueloil(HFO),inpa icula ,a eo  e ylowquali y,lowe cos ,anda e hemos used,andindi e en g ades[19].As hedis illa eclass, hele e  e e s o hei  p ope iesunde In e na ionalO ganiza ion o S anda diza ion(ISO)8217:2017[19].  0 100 200 300 400 500 600 Wo ldMa i imeEngineCapaci y Wind PV Gas Coal Nuclea Oil Hyd o Biomass O he GW Figu e 1. Wo ld ma i ime engine powe compa ed o Eu opean ins alled powe (The igu e was cons uc ed based on da a cap u ed om Balcombe e .al (2019) [12] and S a is a (2020) [15]. The e a e essen ially h ee ca ego ies o ma ine engines: slow speed, medium speed, and high-speed, no mally classi ied in kno s (15–25 kno s) [ 12 , 16 ]. The ca ego y choice depends on he size, engine speed, and pu pose. Mode a e speed engines egula ly unc ion unde 350 e olu ions pe minu e ( pm) and ha e excep ionally low uel u iliza ion. As a as size is conce ned, slow-speed engines a e he la ges engines on he plane ha use hea y uel oil (HFO) o igni ion [13,17]. 2.2. Ma ine Bunke Classi ica ion Ma ine uel can be classi ied as dis illa e, in e media e, and esidual (Table 1). The dis illa e classes a e named ma ine gas oil (MGO) o ma ine dis illa e oil (MDO) which ha e di e en g ades (DMA, DMB, DMX, DMZ). The le e s “A”, “B” . . . “Z”, e e o he pa icula p ope ies unde he p oduc speci ica ion, ISO 8217:2017 [18,19]. Table 1. Classi ica ion o ma ine uels ( he able was cons uc ed based on da a a ailable in s udies o Mohd Noo e al. (2018) [13] and Ve mie e (2021) [19]). Ma ine Fuel Fuel Type Fuel G ade Common Indus ial Name De ini ion MGO Dis illa e DMX, DMA, DMB, DMZ Gas oil o ma ine gas oil, ma ine diesel oil Iden ical o au omo i e diesel MDO I con ains a mix u e o hea y uel oil and a highe p opo ion o ma ine gas oil. IFO In e media e IFO 180, 380 In e media e uel oil such as ma ine diesel oil, a mix u e o a highe p opo ion o HFO wi h MGO. HFO Residual RMA, RMB, RMD, RME, RMG, RMK Fuel oil o esidual uel oil The lowes g ade o ma ine uel. I is a esidual oil, high- iscosi y, and equi es p ehea ing be o e use. Ene gies 2022,15, 3571 4 o 30 The in e media e uel oil (IFO) is di ided in o g ades 180 and 380, hese numbe s co espond o he maximum kinema ic iscosi y o he esidual uel, in squa e millime e s pe second (mm2/s) a 50 ◦C [19]. Residual uels, also called esidual ma ine uels (RMA, RMB, RMD, RME, RMG, RMK) o hea y uel oil (HFO), in pa icula , a e o e y low quali y, lowe cos , and a e he mos used, and in di e en g ades [ 19 ]. As he dis illa e class, he le e e e s o hei p ope ies unde In e na ional O ganiza ion o S anda diza ion (ISO) 8217:2017 [19]. 2.3. In e na ional Shipping Emissions: Cu en and Fo ecas Scena ios Mos CO 2 emissions om in e na ional shipping a e p oduced by bulk ca ie s, con- aine ships, and oil anke s (15%, 18%, and 11% o he o al shipping emissions, espec- i ely). The high emissions o hese essels a e di ec ly connec ed wi h he long jou neys o deli e ing hei ca go ac oss seas and con inen s [12,20]. The sha e o consump ion by uel ype is 72% o HFO, 26% o ma ine gas oil, and 2% o LNG [ 12 , 21 ]. The main conce n o HFO consumed by he shipping sec o is he sul u con en es ima ed a 13% o he wo ld’s sul u emissions [ 12 , 22 ]. SOx emissions con ibu e o se e al en i onmen al p oblems, such as acidi ica ion o he wa e and soil, and human heal h issues [12,23]. The new egula ions al eady in o ce imposed by Annex VI o he IMO ha e limi ed he sul u con en in Emission Con ol A eas (ECA) (0.1%) (0.1% m/m) and non-ECA a eas (0.5% m/m), eplacing he HFO wi h MGO o LNG [ 12 ]. The ECA a eas a e comp ised o he Bal ic Sea, No h Sea, Eas and Wes coas s o he Uni ed S a es, and he Ca ibbean Sea wi hin a dis ance o 200 nau ical miles [ 24 ], while non-ECA a eas ep esen he es o he wo ld. Conce ning NOx emissions, Tie I came in o o ce in 2000 wi h s anda ds anging om app oxima ely 10 o 17 g/kWh, acco ding o speed engines, Tie 2 (in 2011) os e ed 20% NOx educ ion below Tie 1, and Tie 3 s anda ds applied o he NOx Emission Con ol A ea (NECA) (The same egions o ECA a eas as sul u con ol) o engines ins alled a e 1 Janua y 201 6, wi h 80% NOx educ ion below Tie 1 [ 25 ]. Regula ion 13 o Ma pol Annex VI s ipula es ha he emission con ol o all ship engines is designed o powe s abo e 130 kilowa s (kW) [26] . Al hough egula ions ega ding SOx and NOx a e s ic e , he CO 2 emission educ ion measu es a e s ill weak and insu icien . The In e na ional Renewable Ene gy Agency (IRENA) [ 27 ] ecen ly published a epo p ojec ing he uel demand in he shipping sec o in 7.9–12.4 EJ by 2050, lis ing he mos ele an con ibu ing ac o s: global economic g ow h, economic g ow h in eme ging ma ke s, shi owa d cleane cooking uels, s ong g ow h in he pe ochemical sec o , egional ade ag eemen s, and cleane ene gy ansi ion. 2.4. Ma i ime Sec o and CO2Emissions CO 2 emissions in he ma i ime sec o a e o ecas o each alues wo- old highe han cu en le els by 2050. This scena io aised IMO conce ns o plan e ec i e measu es agains he uncon olled emissions o he sec o . The 72nd Ma ine En i onmen P o ec ion Commi ee (MEPC) esolu ion o he IMO se he goal o educing emissions by hal in he nex h ee decades [24]. The scena ios in Figu e 2p edic he GHG emissions by 2050, hose da a we e con- s uc ed by he IMO in he Thi d G eenhouse Gases S udy o IMO [ 20 ], ollowing he assump ions below: • Combina ions o he Rep esen a i e Concen a ion Pa hways (RCP) ( he RCPs (RCP2.6, RCP4.5, RCP6, and RCP8.5) a e p ojec ions adop ed by he In e go e nmen al Panel o Clima e Change (IPCC) which ep esen s he ange o adia i e o cing caused by he GHG emissions in he yea 2100 (2.6, 4.5, 6, and 8.5 W/m 2 , espec i ely) [ 20 ]), and he Sha ed Socioeconomic Pa hway (SSP) ( he SSPs a e p ojec ions un il he yea 2100 u ilized by he IPCC which o ecas s social-economic global changes and d aws he GHG emissions in i e scena ios wi h di e en clima e policies: SSP1 (sus ainabili y), Ene gies 2022,15, 3571 5 o 30 SSP2 (in e media e challenge), SSP3 ( egional i al y), SSP4 (inequali y), and SSP5 ( ossil- ueled de elopmen ) [20]) in all scena ios. • Scena ios 1–4 we e simula ed by combining he RCP and SSP wi h high pene a ion o lique ied na u al gas (LNG) and high imp o emen in ene gy e iciency (60%) o e he 2012 lee a e age by 2050. • Scena ios 5–8 we e simula ed by combining he RCP and SSP wi h high pene a ion o LNG and lowe imp o emen in ene gy e iciency (40%) o e he 2012 lee a e age by 2050. • Scena ios 9–12 we e simula ed by combining he RCP and SSP wi h low pene a ion o LNG and high imp o emen in ene gy e iciency (60%) o e he 2012 lee a e age by 2050. • Scena ios 13–16 a e he business as usual scena io (BAU) which we e simula ed by combining he RCP and SSP wi h low pene a ion o LNG and lowe imp o emen in ene gy e iciency (40%) o e he 2012 lee a e age by 2050. •The do ed line is he ambi ious a ge o 438 M CO2eq by 2050 p oposed by IMO. Ene gies2022,15,xFORPEERREVIEW5o 31   Thescena iosinFigu e2p edic  heGHGemissionsby2050, hoseda awe e cons uc edby heIMOin heThi dG eenhouseGasesS udyo IMO[20], ollowing he assump ionsbelow:  Combina ionso  heRep esen a i eConcen a ionPa hways(RCP)( heRCPs (RCP2.6,RCP4.5,RCP6,andRCP8.5)a ep ojec ionsadop edby he In e go e nmen alPanelo Clima eChange(IPCC)which ep esen s he angeo  adia i e o cingcausedby heGHGemissionsin heyea 2100(2.6,4.5,6,and8.5 W/m2, espec i ely)[20]),and heSha edSocioeconomicPa hway(SSP)( heSSPsa e p ojec ionsun il heyea 2100u ilizedby heIPCCwhich o ecas ssocial‐economic globalchangesandd aws heGHGemissionsin i escena ioswi hdi e en clima e policies:SSP1(sus ainabili y),SSP2(in e media echallenge),SSP3( egional i al y), SSP4(inequali y),andSSP5( ossil‐ ueledde elopmen )[20])inallscena ios.  Scena ios1–4we esimula edbycombining heRCPandSSPwi hhighpene a ion o lique iedna u algas(LNG)andhighimp o emen inene gye iciency(60%)o e  he2012 lee a e ageby2050.  Scena ios5–8we esimula edbycombining heRCPandSSPwi hhighpene a ion o LNGandlowe imp o emen inene gye iciency(40%)o e  he2012 lee  a e ageby2050.  Scena ios9–12we esimula edbycombining heRCPandSSPwi hlowpene a ion o LNGandhighimp o emen inene gye iciency(60%)o e  he2012 lee a e age by2050.  Scena ios13–16a e hebusinessasusualscena io(BAU)whichwe esimula edby combining heRCPandSSPwi hlowpene a iono LNGandlowe imp o emen  inene gye iciency(40%)o e  he2012 lee a e ageby2050.  Thedo edlineis heambi ious a ge o 438M CO2eqby2050p oposedbyIMO  Figu e2.GHGlong‐ e mscena io(The igu ewasadjus edonda aa ailableinThi dG eenhouse GasS udy2014)[20]. 2800 438 0 500 1000 1500 2000 2500 3000 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 Scena io1RCP8.5/SSP5 Scena io2RCP6.0/SSP1 Scena io3RCP4.5/SSP3 Scena io4RCP2.6/SSP4 Scena io5RCP8.5/SSP5 Scena io6RCP6.0/SSP1 Scena io7RCP4.5/SSP3 Scena io8RCP2.6/SSP4 Scena io9RCP8.5/SSP5 Scena io10RCP6.0/SSP1 Scena io11RCP4.5/SSP3 Scena io12RCP2.6/SSP4 Scena io(BAU)13RCP8.5/SSP5 Scena io14(BAU)RCP6.0/SSP1 Scena io15(BAU)RCP4.5/SSP3 Scena io16(BAU)RCP2.6/SSP4 IMO M CO 2 eq Figu e 2. GHG long- e m scena io (The igu e was adjus ed on da a a ailable in Thi d G eenhouse Gas S udy 2014) [20]. Recen ly he IMO assumed ha he measu es o educe emissions mus be imple- men ed as ea ly as possible o his cen u y, se ing ambi ion le els and guiding p inci- ples [24]. GHG educ ions a e s ill only based on he Ene gy E iciency Design Index (EEDI) and he Ship Ene gy E iciency Managemen Plan (SEEMP), which a e in line wi h he echnical and ope a ional ca ego ies [ 28 , 29 ]. Technical measu es ocus on design and imp o emen in ene gy e iciency, p opulsion, powe sys em, and low ca bon uels. Some ac ions can be implemen ed h ough e o i ing o exis ing ships, while o he s only in Ene gies 2022,15, 3571 6 o 30 new ships [ 28 ]. E en so, al e na i es a e equi ed and he sec o has u ned i s a en ion o al e na i e op ions. Nex , we ou line he me hods o he app oach and he mos ecen s udies ha ci e al- e na i e sou ces as one o he deca bonizing measu es o be applied in he ma i ime sec o . 3. Ma e ial and Me hods A he momen he e a e se e al s udies ega ding low ca bon al e na i e uels, ne e - heless ew o hem apply o he ma i ime sec o . To highligh impo an a icles and e iews, a sys ema ic analysis was made o he Web o Knowledge online da abase se ice by Thomson Reu e s Inc. S udies we e adap ed [ 30 ] om he simila s udy al eady a ailable in he li e a u e [ 31 ]. Based on a combina ion o wo ds o ind pape s which men ion cleane uels as an al e na i e o deca bonize he ma i ime sec o . Re ining The e ining me hod will be elabo a ed on in 3 s eps. The 1s s ep is aken in he ad anced sea ch by applying he ield ag displayed in Table 2below. Table 2. Keywo ds e ining. 1s S ep o Re ining Keywo d Resea ch TS = ( enewable ene gy o bio uels o ad anced bio uel o al e na i e uels o low ca bon uel o biome hanol o bioe hanol o biodiesel o me hyl es e o biogas o bio LNG o bio lique ied na u al gas o Hyd o ea ed Vege able oil o enewable uel o py olysis oil o Fische T opsch o hyd ogen o hyd o he mal lique ac ion o ba e ies o s a e o he a echnologies) and TS = (deca b oniza ion o low ca bon emissions o deca bonize o g eenhouse gases educ ions o GHG educ ions o g eenhouse gases emissions o GHG emissions) and TS = (Ma i i me sec o o shipping sec o o in e na ional shipping sec o o ma i ime anspo a ion o deca bonize in e na ional ma i ime o al e na i e uel o ma ine applica ions o ma ine diesel engines) TS ep esen s he opic and he bina y a iables OR, AND ela e he keywo ds wi h he in en ion o inding pape s on he Web o Science da abase. The 2nd s ep is o ela e only pape s and e iews, in he English, du ing he pe iod om Janua y 2000 o Janua y 2022. The 3 d s ep is conduc ed manually, he pape s which app oach al e na i e uels as cleane sou ces o he ma i ime deca boniza ion. 4. Resul and Discussion 4.1. Selec ed Pape s and Desc ip i e S a is ics Figu e 3displays he h ee s eps sugges ed, as well as hei esea ch c i e ia. The i s selec ed s udies eached an o e all combina ion o 328 a icles, e iews, p oceedings pape s, and book chap e s, wi h pape s and e iews accoun ing o 91% o he o al. Ne e heless, i was necessa y o ca y ou manual e ining o he deca boniza ion o he ma i ime sec o and al e na i e and low ca bon uels. A e manual e ining, he RQ1 can be answe ed, whe e 91 pape s and 12 e iews (Figu e 3) we e selec ed as a baseline o pa o he s a e o he a . The g ow h in publica ions in 2018 (Figu e 4) was e iden , om only 3 (2.91% o o al) in 2017 o 29 (28.16% o o al) in 2021. The yea s om 2020 o 2022 co espond o 65% o he pape s conce ned, d i en by he IMO’s ecen manda o y equi emen s o g eenhouse gas emissions which gained p ominence due o eal in en ions o educ ion ecen ly. Ene gies 2022,15, 3571 7 o 30 Ene gies2022,15,xFORPEERREVIEW7o 31   Ne e heless,i wasnecessa y oca you manual e ining o  hedeca boniza iono  he ma i imesec o andal e na i eandlowca bon uels. A e manual e ining, heRQ1canbeanswe ed,whe e91pape sand12 e iews (Figu e3)we eselec edasabaseline o pa o  hes a eo  hea .Theg ow hin publica ionsin2018(Figu e4)wase iden , omonly3(2.91%o  o al)in2017 o29 (28.16%o  o al)in2021.Theyea s om2020 o2022co espond o65%o  hepape s conce ned,d i enby heIMO’s ecen manda o y equi emen s o g eenhousegas emissionswhichgainedp ominencedue o ealin en ionso  educ ion ecen ly.  Figu e3.Rela eddocumen son e ineds eps.  Figu e4.Publica ionso e  heyea s. We ind heanswe  oRQ2in heselec edwo ks,whichhighligh  hehigh con ibu iono  heEu opeancoun ies(57%)(Table3),p obablyd i enby hes ic  ules inplacesince2015in heBal ic, heNo hSea,andNo hAme icancoas  ega dingSOx andNOx.Mo eo e ,Eu opehasahighene gydependence, hus he eisacommi men  o educeno only heemissionsassocia edwi h ossilsou cesusedin hema i imesec o  1s S ep‐328documen s ● Resea chc i e ia: Combina iono keywo ds Webo ScienceDa aBase ● Pe iod:Janua yo 2000 oJanua yo 2022 2ndS ep‐297documen s ● Resea chc i e ia: ● Types:A icles,Re iews ● Language:English 3 dS ep‐103documen s ● ExclusionC i e ia: ● Dono add essMa i ime T anspo a ion Deca boniza ionand al e na i e ueluse(194 pape selmina eda e  abs ac , i leandkey wo ds ead) 0.00 5.00 10.00 15.00 20.00 25.00 30.00 0 5 10 15 20 25 30 35 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Numbe o publica ions % Figu e 3. Rela ed documen s on e ined s eps. Ene gies2022,15,xFORPEERREVIEW7o 31   Ne e heless,i wasnecessa y oca you manual e ining o  hedeca boniza iono  he ma i imesec o andal e na i eandlowca bon uels. A e manual e ining, heRQ1canbeanswe ed,whe e91pape sand12 e iews (Figu e3)we eselec edasabaseline o pa o  hes a eo  hea .Theg ow hin publica ionsin2018(Figu e4)wase iden , omonly3(2.91%o  o al)in2017 o29 (28.16%o  o al)in2021.Theyea s om2020 o2022co espond o65%o  hepape s conce ned,d i enby heIMO’s ecen manda o y equi emen s o g eenhousegas emissionswhichgainedp ominencedue o ealin en ionso  educ ion ecen ly.  Figu e3.Rela eddocumen son e ineds eps.  Figu e4.Publica ionso e  heyea s. We ind heanswe  oRQ2in heselec edwo ks,whichhighligh  hehigh con ibu iono  heEu opeancoun ies(57%)(Table3),p obablyd i enby hes ic  ules inplacesince2015in heBal ic, heNo hSea,andNo hAme icancoas  ega dingSOx andNOx.Mo eo e ,Eu opehasahighene gydependence, hus he eisacommi men  o educeno only heemissionsassocia edwi h ossilsou cesusedin hema i imesec o  1s S ep‐328documen s ● Resea chc i e ia: Combina iono keywo ds Webo ScienceDa aBase ● Pe iod:Janua yo 2000 oJanua yo 2022 2ndS ep‐297documen s ● Resea chc i e ia: ● Types:A icles,Re iews ● Language:English 3 dS ep‐103documen s ● ExclusionC i e ia: ● Dono add essMa i ime T anspo a ion Deca boniza ionand al e na i e ueluse(194 pape selmina eda e  abs ac , i leandkey wo ds ead) 0.00 5.00 10.00 15.00 20.00 25.00 30.00 0 5 10 15 20 25 30 35 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Numbe o publica ions % Figu e 4. Publica ions o e he yea s. We ind he answe o RQ2 in he selec ed wo ks, which highligh he high con ibu ion o he Eu opean coun ies (57%) (Table 3), p obably d i en by he s ic ules in place since 2015 in he Bal ic, he No h Sea, and No h Ame ican coas ega ding SOx and NOx. Mo eo e , Eu ope has a high ene gy dependence, hus he e is a commi men o educe no only he emissions associa ed wi h ossil sou ces used in he ma i ime sec o bu also o educe he dependence on ex e nal ene gy. Rega ding he anking by coun y, 41 coun ies showed con ibu ions, he i s 5 coun ies accoun ing o 49% o he o al. England and he USA accoun ed o he highes p opo ion (18%), ollowed by China and No way (14%), Ene gies 2022,15, 3571 8 o 30 Ge many and Sweden (12%), and he Ne he lands (5%). The emaining coun ies accoun ed o 4% o less. Table 3. Numbe o s udies pe coun y. Rank Coun ies % Coun ies % Posi ion Region % 1s England 9 G eece 1 1s Eu ope 57 USA 9 No he n I eland 1 2nd Asia 21 2nd China 7 Poland 1 3 d No h Ame ica 12 No way 7 Japan 1 4 h Sou h Ame ica 4 3 d Ge many 6 Aus ia 1 5 h Oceania 3 Sweden 6 Bosnia 1 6 h A ica 2 4 d Ne he lands 5 Cyp us 1 7 h Middle Eas 1 5 h Singapo e 4 Denma k 1 Spain 4 Iceland 1 B azil 4 Li huania 1 6 h Tu key 3 Mal a 1 I aly 3 Mon eneg o 1 Canada 3 Sco land 1 7 h Sou h Ko ea 2 Se bia 1 Taiwan 2 Saudi A abia 1 C oa ia 2 Uni ed A ab Emi a es 1 Finland 2 Fiji 1 I eland 2 Sou h A ica 1 Aus alia 2 Nige ia 1 8 h India 1 Egyp 1 Malaysia 1 To al 100% Conce ning au ho s (RQ3), a o al o 446 au ho s w o e 103 a icles (Appendix A). Fou pe cen o he a icles we e w i en by indi idual au ho s, while 19.42% we e w i en by wo au ho s, 16.50% by h ee au ho s, and 60.19% in ol ed a eam o ou o mo e au ho s (Table 4). Fu he mo e, Table 5shows he lis o he mos p oduc i e au ho s. Lins ad, E. and Xing, H. w o e 3 a icles each. A he same ime, he o he au ho s published ei he wo pape s o one pape each. The e o e, Bouman, EA. and Balcombe, P. ha e he mos ci ed pape s—7% and 14% espec i ely—ou o a o al o 1600 ci ed pape s. Table 4. Numbe o au ho s pe pape . Numbe o Au ho s pe Pape Numbe o Pape s % 13 1 1 12 1 1 11 1 1 10 3 3 9 1 1 8 1 1 7 9 9 6 9 9 5 11 11 4 25 24 3 17 16 2 20 19 1 4 4 To al 103 100 Ene gies 2022,15, 3571 9 o 30 Table 5. Mos p oduc i e and ci ed au ho s. Au ho s Numbe o Pape s %Times Ci ed %Ci a ions pe Pape Au ho s Numbe o Pape s %Times Ci ed %Ci a ions pe Pape Linds ad, E 3 3% 26 2% 9 Law, L 1 1% 0 0% 0 Xing, H 3 3% 37 2% 12 Liu, J 1 1% 0 0% 0 Ampah, JD 2 2% 6 0% 3 Mallouppas, G 1 1% 5 0% 5 Bach, H 2 2% 19 1% 10 Mukhe jee, A 1 1% 2 0% 2 Balcombe, P 2 2% 109 7% 55 Mwangi, JK 1 1% 29 2% 29 Ca alho, F 2 2% 1 0% 1 Nabi, MN 1 1% 8 1% 8 Gabina, G 2 2% 35 2% 18 Nai , A 1 1% 2 0% 2 Lin, CY 2 2% 39 2% 20 Nikolic, D 1 1% 2 0% 2 Mulle -Casse es, E 2 2% 5 0% 3 Nine, RD 1 1% 3 0% 3 Pe cic, M 2 2% 26 2% 13 Nuch u ee, C 1 1% 26 2% 26 Sa i, A 2 2% 1 0% 1 Ogunkunle, O 1 1% 16 1% 16 Shannina, M 2 2% 28 2% 14 O iz-Imedio, R 1 1% 3 0% 3 A ms ong, VN 1 1% 45 3% 45 Pan, HS 1 1% 32 2% 32 A ilhan, S 1 1% 22 1% 22 Peng, WH 1 1% 8 1% 8 Awoyomi, A 1 1% 4 0% 4 Pe zold, A 1 1% 53 3% 53 Ay ali, T 1 1% 0 0% 0 P ei e , A 1 1% 13 1% 13 ben B ahim 1 1% 14 1% 14 Popp, L 1 1% 0 0% 0 Bice , Y 1 1% 30 2% 30 P asad, RD 1 1% 2 0% 2 Bouman, EA 1 1% 226 14% 226 P ussi, M 1 1% 14 1% 14 Cassa , MP 1 1% 0 0% 0 Righi, M 1 1% 38 2% 38 Chen, ZS 1 1% 0 0% 0 Rizzo, AM 1 1% 0 0% 0 Chiong, MC 1 1% 1 0% 1 Rod iguez, CG 1 1% 0 0% 0 Choi, W 1 1% 16 1% 16 Schons eine , K 1 1% 10 1% 10 Ch is odoulou, A 1 1% 1 0% 1 Se a, P 1 1% 15 1% 15 Co bin, JC 1 1% 14 1% 14 Spoo -Tuomi, K 1 1% 11 1% 11 Co ez, L 1 1% 0 0% 0 S yh e, L 1 1% 68 4% 68 Cze manski, E 1 1% 4 0% 4 Taccani, R 1 1% 4 0% 4 Elka as, AG 1 1% 3 0% 3 Tan, ECD 1 1% 1 0% 1 Gallo, M 1 1% 5 0% 5 Tanze , SE 1 1% 20 1% 20 Ga cia, B 1 1% 0 0% 0 To es-Ga cia, M 1 1% 11 1% 11 Ghenai, C 1 1% 43 3% 43 T i yza, NL 1 1% 0 0% 0 Gilbe , P 1 1% 71 4% 71 T ed en, IO 1 1% 0 0% 0 Gonzalez-A ias, J 1 1% 0 0% 0 Tzanna os, E 1 1% 5 0% 5 Gysel, NR 1 1% 11 1% 11 Ushako , S 1 1% 7 0% 7 Hagos, DA 1 1% 29 2% 29 an de K o 1 1% 0 0% 0 Hansson, J 1 1% 29 2% 29 Wahl, J 1 1% 0 0% 0 Helgason, R1 1 1% 11 1% 11 Wang, H 1 1% 4 0% 4 He dzik, J 1 1% 0 0% 0 Wang, ZC 1 1% 2 0% 2 Hi da is, SE 1 1% 47 3% 47 Wineb ake, JJ 1 1% 5 0% 5 Ho a h, S 1 1% 33 2% 33 Winnes, H 1 1% 86 5% 86 Hwang, SS 1 1% 6 0% 6 Wu, P 1 1% 17 1% 17 Inal, OB 1 1% 26 2% 26 Yildi im Peksen, D 1 1% 0 0% 0 Kesieme, U 1 1% 27 2% 27 Yusu , AA 1 1% 0 0% 0 Khan, MY 1 1% 23 1% 23 Zah aee, SM 1 1% 0 0% 0 Kis ne , L 1 1% 1 0% 1 To al 103 100% 1600 100% Table 6highligh s he equency o he pape s published in he jou nals (RQ4). The Jou nal o Cleane P oduc ion,Sus ainabili y, and T anspo a ion Resea ch Pa D s and ou , wi h wen y-one pe cen o all published pape s (21%), ollowed by Ene gies and Ene gy (12%), he In e na ional Jou nal o Hyd ogen Ene gy, and Renewable & Sus ainable Ene gy Re iews (10%). The emaining jou nals published only ou pape s o less. The i s en pape s (10% o he o al) lis ed in Table 7co esponded o 768 ci a ions (48% o he o al) which is almos hal o he selec ed documen s, p obably o he eason hey a e one o he i s e e ences o al e na i e uel use as an op ion o educe GHG emissions and o he pollu an gases. The majo indings om hose s udies a e summa ized in sequence (Table 7). Ene gies 2022,15, 3571 16 o 30 Table 8. GHG emissions o di e en uels ( he able was cons uc ed based on da a a ailable in Balcombe e .al (2019) s udies [12]. Fuel Types gCO2eq/kWh LNG 580–870 Hyd ogen 113–997 Biodiesel 90–430 Me hanol 50–290 Py olysis Oil 250–340 FT-diesel 50 HVO 210–400 E hanol 140–250 SVO 290 Ad anced bio uels, such as ad anced bio-me hanol, bio-me hane, FT-diesel, and py olysis oil can impac he CO 2 eq ca bon oo p in u he (Table 8) due o he ac ha hey do no compe e wi h ood and eed p oduc ion since he eeds ock comes mainly om was e [12]. The s udies by Bouman e al. (2017) [ 28 ] p esen ed bio uels as displaying he bigges po en ial o educing GHG emissions in he ma i ime sec o . Fu he mo e, hei biodeg ad- abili y is an ad an age ega ding acciden al spills [ 12 , 68 ]. Se a and Fancello (2020) [ 69 ] ci ed he ad an ages o bio uels in connec ion wi h hei biodeg adabili y. Howe e , he au ho s highligh ed he a en ion o cons ain s on he emissions associa ed wi h di ec and indi ec land use. In s udies by Law e al. [ 70 ] he impo ance o he li e cycle assessmen (well- o-wake) o e he al e na i e uel use is men ioned. The en i e supply chain mus ensu e ha all he impac s some uels can cause and a well- o-wake ene gy assessmen o ma ine uels s ill lacking conside a ion in li e a u e be accoun ed o . F om se e al bio uel ypes and ou es, biodiesel and bio-me hanol we e ci ed as good op ions in e ms o cos s, a ailabili y, and le el o echnology. Howe e , he main p oblems conce n NOx, SOx, and PM. The au ho also concluded ha hyd ogen and ammonia a e he wo s op ions due o he o e all ene gy consumed and high cos s o p oduc ion. P ussi e al. [ 71 ] also men ioned ha ze o-emission in al e na i e uels only occu s om a ank- o-wake pe spec i e, since many emissions and impac s may occu be o e hei p oduc ion and o he GHG me hodologies mus be used (well- o- ank). The au ho also commen ed ha i al e na i e op ions do no come om a enewable basis, he ca bon oo p in can be highe han he con en ional ossil sou ces al eady used. The supply chain o al e na i e uels assessmen is a de e minan o e i y how clean some uels can be, and he ull li e cycle assessmen is he mos impo an ool ci ed by some au ho s o quan i y he many impac s caused by di e en ene gy sou ce op ions. 4.1.11. Ma i ime Bio uel Use and Ba ie s The new manda o y ules conce ning ma i ime anspo can inc ease he cos consid- e ably o he sec o by a ound USD 60 billion pe annum. The uel expendi u e ep esen s almos hal o he ope a ing cos , and i can e lec an inc ease o 10% o he equi alen o he wen y- oo uni (TEU) cos anspo ed [69,72]. Only a ew al e na i e op ions a e cu en ly a ailable and LNG appea s o be he bes ansi o y op ion. Howe e , he pa adigm is in bunke supplie s, who do no wan o make in es men s un il su icien demand is gua an eed, and he ship-owne s do no make in es men s i he e a e no e ueling poin s [ 69 , 73 ]. This obse a ion can also apply o he al e na i e uel op ions. The sea ch o new and manda o y measu es has awakened he conce ns abou he ebound e ec hey can p oduce [ 69 , 74 ]. Fo example, some s udies sugges ha , i he new ECA egula ions a e applied in he Medi e anean Sea, hey can inc ease he cos Ene gies 2022,15, 3571 17 o 30 o ma i ime anspo by abou 6.95 EUR/GJ [ 69 , 75 , 76 ] and os e a modal shi o land anspo , con ibu ing o inc easing CO2emissions [64,69]. Ano he eal p oblem is he spli o incen i es be ween shipowne s and cha e e s. The cos o in es men s in cleane al e na i es is only easible i he o me di ec ly ope a e hei ships o make be e ag eemen s wi h cha e e s, spli ing he economic ad an ages and disad an ages o g eene decisions. As ag eed be ween ship-owne s and he po ope a o s, GHG emission educ ion is subjec o h ee main kinds o isks: business, echnical, and ex e nal [ 69 , 77 ]. The i s conce ns he payback pe iod, he second is a ibu ed o he lack o eliabili y o he ules applied, and he hi d e e s o he cos o uel, policy, and egula ions. An impo an obse a ion has been made by Machado (2019) in B azil [ 78 ]. The implemen a ion o he new ules conce ning 0.5% less sul u emissions can impac he cos o he diesel used in oad anspo . Due o his ac , dis illed ma ine uel is simila o he diesel used in oad anspo a ion. The high demand can impac he lack o uel and consequen ly inc ease he p ice. I can ha e he same impac on i s -gene a ion bio uel, which is al eady being used in blends o oad anspo in many pa s o he wo ld. This conce n men ioned be o e opens up he way o ad anced bio uels and al e na i e uel explo a ion. Howe e , he low de elopmen o his sou ce makes i highly expensi e and discou ages i s use. 5. Conclusions and Sugges ions o he Fu u e The s udy selec ed high-s anda d pape s in he Web o Science da abase o iden i y he con ibu ion o academia in he li e a u e o he use o al e na i e uels in he shipping sec o as a low ca bon op ion. Se e al assessmen s was done o analyze ac o s as numbe o pape s, he mos au ho s, he main egions and how ci ed hose a icles and e iews ha e been employed o con ibu e o educe he GHG emissions in ma i ime sec o . The esea ch was impo an o unde s anding which esou ces ha e con ibu ed mos o he scena io, how hey ha e de eloped, wha is expec ed o he u u e, and why hey a e impo an . Based on keywo d combina ion, 103 a icles we e ound ha men ion bio uels o low ca bon al e na i es used in he ma i ime sec o . The LNG is undoub edly he main low ca bon al e na i e wi h many ships al eady ope a ing wi h his sou ce in he wo ld. Eigh y-eigh pe cen o he pape s e e ed o LNG as an impo an sou ce in he ma i ime sec o o GHG educ ion. Mo eo e , i can signi ican ly educe o he emissions, such as SO x , NO x , and PM. Ne e heless, he me hane slip (me hane ha escapes in o he a mosphe e) is one o he d awbacks due o i s high GHG po en ial. Bio-LNG could be a po en ial op ion, bu p oduc ion is s ill oo low o mee he high demand in he shipping sec o . Hyd ogen is one o he mos ci ed op ions (16.2%). In a ank- o-wheel assessmen , H 2 om ossil sou ces has nil GHG emissions, which can also be highly ca bon-in ensi e when analyzed om a well- o-wheel pe spec i e. Renewable hyd ogen o g een hyd ogen has been widely discussed o he medium- and long- e m, bu he cu en s age o de elopmen and use in he shipping sec o is s ill low. Biodiesel is a enewable and low ca bon sou ce, which ep esen ed 14.5% o o al men ions. This op ion, oge he wi h HVO (3.8%) and SVO (3.4%) a e sou ces ha can be blended in o he cu en ma ine engines wi hou u he modi ica ion. Ne e heless, he main eeds ock comes om ood/ eed sou ces and om de o es ed a eas, which can aise o he issues. Me hanol accoun ed o 23.8% o men ions in he assessed s udies. The la ges ba ie is i s p oduc ion, which is consolida ed only h ough ossil esou ces, and a modes numbe o essels a e al eady unning on his al e na i e uel. A new ecen esou ce widely discussed in academia is ammonia. This uel ( ossil o enewable) is capable o be employed in ICE o ull cells. The esou ce ecei ed 9.8% Ene gies 2022,15, 3571 18 o 30 o men ions in he assessed pape s. Howe e , i s ill appea s as a p omising hope o he u u e since i is s ill limi ed o he esea ch ield. The ad anced ou e o al e na i e uel p oduc ion had an exp essionless con ibu ion. Py olysis oil and Fische –T opsch diesel accoun ed o 5.1 and 4.3% o ci a ions, espec i ely, in he selec ed pape s. Al hough hey ha e an exp essi e con ibu ion o GHG emission educ ions, he d awback is he low de elopmen le el o hose echnologies, lack o s anda ds, and high cos o p oduc ion. In all cases men ioned be o e, he cleane uels a e s ill no su icien ly ep esen a i i y in he ma i ime sec o . P obably due o he lack o incen i es om he p oduc ion and consume demand. Mo eo e , he e is a lo o esis ance om he shipping indus y. The s udy concluded ha se e al ba ie s, such as low echnology de elopmen , cos and accessibili y, shipping indus y, cha e e accep ance, and lack o homogeneous egula ions o e in e na ional wa e s, hampe he de elopmen o new uel sou ces. Some al e na i es can be used as a blend in cu en uels, such as LNG, biodiesel, and me hanol. Mo eo e , lignocellulosic esidues can inc ease hei a ailabili y wi hou cons aining ood and eed p oduc ion, no he compe i ion wi h bio uels al eady used in he oad sec o [63]. In e ms o ends, Ampah e al. [ 31 ] concluded, ha LNG has been he mos in es- iga ed al e na i e sou ce, mainly d i en by he ac ha i is an abundan cleane uel; u he mo e, hei p oduc ion, anspo a ion, s o age, and inal use hold consolida ed echnologies wi h cos -compe i i eness. Howe e , he au ho also concluded ha he e is a new esea ch endency o e me hanol, ammonia, and hyd ogen. Top expe s belie e ha implemen a ion may be di icul due o he associa ed high cos . Ne e heless, high cos compa ed o wha ? I is clea ha ossil uel s ill accoun s o exp essi e subsidies in he wo ld, and he ma i ime sec o uses he cheapes uel compa ed o o he anspo modes. Consequen ly, he ques ion one mus ask is wha p ice will we pay in he u u e? This s udy has been impo an o show he lack o in-dep h s udies on cleane uel op ions in he ma i ime sec o . The p i a e sec o and go e nmen s mus s a ac ing now o s imula e esea ch and de elopmen , which, consequen ly, will soon sp ead o he shipping indus y. The s udy e iew he ein has no included p ac ical s udies on he al e na i e p oduc- ion and es s, whe e all o hem a e limi ed only in heo y. P ac ical s udies a e essen ial o gain he eliabili y and con idence o he shipping indus y. O he s udies, i.e., on he b eak-e en le el o oil p ice, could be ca ied ou o assay a which p ice le el o oil would he cleane sou ces be compa able o he cu en ossil uels. The de elopmen o he ca bon ma ke will also be an impo an measu e o s imula ing ma i ime sec o deca boniza ion. Au ho Con ibu ions: V.A.d.S.: concep ualiza ion, me hodology, in es iga ion, w i ing—o iginal d a , w i ing— e iew and edi ing; P.P.d.S.: esou ces, concep ualiza ion, alida ion, supe ision, w i ing— e iewand edi ing; L.M.V.S.: esou ces, concep ualiza ion, alida ion, supe ision, w i ing— e iew and edi ing. All au ho s ha e ead and ag eed o he published e sion o he manusc ip . Funding: This Resea ch was unded by he Science and Technology Founda ion (FCT), Minis y o Science and Highe Educa ion (MCTES), Eu opean Social Fund (FSE), and Eu ope Union (EU), unde he g an numbe PD/BD/142848/2018. Ins i u ional Re iew Boa d S a emen : No applicable. In o med Consen S a emen : No applicable. Da a A ailabili y S a emen : No applicable. Ene gies 2022,15, 3571 19 o 30 Acknowledgmen s: The au ho would like o acknowledge he inancial suppo ecei ed om he Science and Technology Founda ion (FCT), Minis y o Science and Highe Educa ion (MCTES), Eu opean Social Fund (FSE), and Eu ope Union (EU), unde he g an numbe PD/BD/142848/2018. Pa ícia P. Sil a acknowledges ha his wo k has been pa ially suppo ed by he Eu opean Regional De elopmen Fund in he amewo k o COMPETE 2020 P og amme and he FCT hough p ojec T4ENERTEC (POCI-01-0145-FEDER-029820), by he FCT unde p ojec s UID/MULTI/00308/2020 and UIDB/05037/2020 and by he Ene gy o Sus ainabili y Ini ia i e o he Uni e si y o Coimb a. Con lic s o In e es : The au ho s decla e ha hey ha e no known compe ing inancial in e es s o pe sonal ela ionships ha could ha e appea ed o in luence he wo k epo ed in his pape . Abb e ia ions €Eu os BAU Business-as-usual Bio-LNG Bio lique ied na u al gas Bio-SNG Bio syn he ic na u al gas CO2Ca bon dioxide CH4Me hane DMA Des ila e ma ine oil A DMB Des ila e ma ine oil B DMX Dis illa e ma ine oil X DMZ Dis illa e ma ine oil Z EEDI Ene gy E iciency Design Index FT-diesel Fische –T opsch diesel gCO2eq G am o equi alen ca bon dioxide GHG G eenhouse gases GHG G eenhouse gases GJ Gigajoule GW Gigawa HFO Hea y uel oil HVO Hyd o ea ed ege able oil ICE In e nal combus ion engine IEA In e na ional Ene gy Agency IFO In e media e uel oil IGC In e na ional Code o he Cons uc ion and Equipmen o Ships Ca ying Lique ied Gases in Bulk IRENA In e na ional Renewable Ene gy Agency IMF In e media e ma ine uel IMO In e na ional Ma i ime O ganiza ion ISO In e na ional O ganiza ion o S anda diza ion kWh Kilowa -hou LNG Liqui ied na u al gas Ma pol In e na ional Con en ion o he P e en ion o Pollu ion om Ships MBOE Million ba el o oil equi alen MCDA Mul i-c i e ia decision analysis MDO Ma ine dis illa e oil LNG Liqui ied na u al gas MBOE Million Ba el o Oil Equi alen MCDA mul i-c i e ia decision analysis MDO Ma ine dis illa e oil M CO2eq Million ons o equi alen ca bon dioxide N2O Ni ous oxide RMA Residue ma ine oil A RMB Residual ma ine oil B RMD Residual ma ine oil D RME Residual ma ine oil E Ene gies 2022,15, 3571 20 o 30 RMF Residue ma ine Fuel RMG Residual ma ine oil G RMK Residual ma ine oil K RPM Re olu ion pe minu e RQ Resea ch ques ion s Second SECA Sul u Emissions Con ol A ea SEEMP Ship Ene gy E iciency Managemen Plan SOx Sul u oxide SVO S aigh ege able oil SSP Sha ed socio-economic pa hway Tonne TEU Twen y equi alen uni s USA Uni ed S a es o Ame ica USD US Dolla WoS Web o Science Appendix A Table A1. Selec ed a icles. Numbe A icle Ti le Au ho s 1Re o i ing owa ds a g eene ma ine shipping u u e: Reassembling ship uels and lique ied na u al gas in No way [79] 2 S udy on cha ac e is ics o ma ine hea y uel oil and low ca bon alcohol blended uels a di e en empe a u es [80] 3Li e cycle assessmen o diesel and hyd ogen powe sys ems in ugboa s [81] 4Ca bon aba emen cos o hyd ogen-based syn he ic uels-A gene al amewo k exempla ily applied o he ma i ime sec o [82] 5Decision suppo me hods o sus ainable ship ene gy sys ems: A s a e-o - he-a e iew [83] 6Biogas upg ading o biome hane as a local sou ce o enewable ene gy o powe ligh ma ine anspo : P o i abili y analysis o he coun y o Co nwall [84] 7Blending o Hyd o he mal Lique ac ion Bioc ude wi h Residual Ma ine Fuel: An Expe imen al Assessmen [85] 8Possibili ies o Ammonia as Bo h Fuel and NOx Reduc an in Ma ine Engines: A Nume ical S udy [86] 9In luence o was e oil-biodiesel on oxic pollu an s om ma ine engine coupled wi h emission educ ion measu es a a ious loads [87] 10 Global u u es o ade impac ing he challenge o deca bonize he in e na ional shipping sec o [88] 11 P ospec s o ca bon-neu al ma i ime uel p oduc ion in B azil [89] 12 A Compa ison o Al e na i e Fuels o Shipping in Te ms o Li ecycle Ene gy and Cos [70] 13 Reduc ion o ma i ime GHG emissions and he po en ial ole o E- uels [90] 14 Pa icle-Gaseous pollu an emissions and cos o global biomass supply chain ia ma i ime anspo a ion: Full-scale syne gy model [91] 15 Re iewing wo decades o cleane al e na i e ma ine uels: Towa ds IMO’s deca boniza ion o he ma i ime anspo sec o [31] 16 Challenges and oppo uni ies o ma ine p opulsion wi h al e na i e uels [92] 17 Techno-economic and En i onmen al Compa ison o In e nal Combus ion Engines and Solid Oxide Fuel Cells o Ship Applica ions [93] Ene gies 2022,15, 3571 21 o 30 Table A1. Con . Numbe A icle Ti le Au ho s 18 A S udy in o he A ailabili y, Cos s and GHG Reduc ion in D op-In Bio uels o Shipping unde Di e en Regimes be ween 2020 and 2050 [94] 19 En i onmen al impac assessmen o hyd ogen-based auxilia y powe sys em onboa d [95] 20 Bio uels o Ma i ime T anspo a ion: A Spa ial, Techno-Economic, and Logis ic Analysis in B azil, Eu ope, Sou h A ica, and he USA [96] 21 Pe spec i e Use o Fas Py olysis Bio-Oil (FPBO) in Ma i ime T anspo : The Case o B azil [97] 22 Powe - o-Ships: Fu u e elec ici y and hyd ogen demands o shipping on he A lan ic coas o Eu ope in 2050 [98] 23 How can LNG- uelled ships mee deca bonisa ion a ge s? An en i onmen al and economic analysis [46] 24 Technical eliabili y o shipboa d echnologies o he applica ion o al e na i e uels [99] 25 Deca boniza ion o Ma ine Fuels-The Fu u e o Shipping [100] 26 Bio uel Op ions o Ma ine Applica ions: Technoeconomic and Li e-Cycle Analyses [101] 27 Al e na i e uel op ions o low ca bon ma i ime anspo a ion: Pa hways o 2050 [102] 28 The Posi ion o Ammonia in Deca bonising Ma i ime Indus y: An O e iew and Pe spec i es: Pa I Technological ad an ages and he momen um owa ds ammonia-p opelled shipping [103] 29 Blending new and old in sus ainabili y ansi ions: Technological alignmen be ween ossil uels and bio uels in No wegian coas al shipping [104] 30 Lique ied Na u al Gas as Ship Fuel: A Mal ese Regula o y Gap Analysis [105] 31 Can Ma ke -based Measu es S imula e In es men s in G een Technologies o he Aba emen o GHG Emissions om Shipping? A Re iew o P oposed Ma ke -based Measu es [106] 32 Deca boniza ion in Shipping Indus y: A Re iew o Resea ch, Technology De elopmen , and Inno a ion P oposals [107] 33 Po en ial and limi ing ac o s in he use o al e na i e uels in he Eu opean ma i ime sec o [71] 34 P oduc ion o al e na i e ma ine uels in B azil: An in eg a ed assessmen pe spec i e [43] 35 G een hyd ogen as an al e na i e uel o he shipping indus y [108] 36 Ne Ze o o he In e na ional Shipping Sec o ? An Analysis o he Implemen a ion and Regula o y Challenges o he IMO S a egy on Reduc ion o GHG Emissions [109] 37 Analysis and Modeling he Ene gy Sys em o a Chemical Tanke by LEAP [110] 38 Fuel Cell Powe Sys ems o Ma i ime Applica ions: P og ess and Pe spec i es [111] 39 Ene gy e iciency o in eg a ed elec ic p opulsion o ships—A e iew [112] 40 Li e-cycle cos assessmen o al e na i e ma ine uels o educe he ca bon oo p in in sho -sea shipping: A case s udy o C oa ia [113] 41 A comp ehensi e e iew on coun e measu es o CO2emissions om ships [114] 42 Nume ical analysis o economic and en i onmen al bene i s o ma ine uel con e sion om diesel oil o na u al gas o con aine ships [115] 43 A Pe spec i e on Bio uels Use and CCS o GHG Mi iga ion in he Ma ine Sec o [116] 44 Deca bonizing Ma i ime T anspo : The Impo ance o Engine Technology and Regula ions o LNG o Se e as a T ansi ion Fuel [117] 45 Renewable Ammonia as an Ene gy Fuel o Ocean Explo a ion and T anspo a ion [118] Ene gies 2022,15, 3571 22 o 30 Table A1. Con . Numbe A icle Ti le Au ho s 46 Exhaus emissions and engine pe o mance analysis o a ma ine diesel engine uelled wi h Pa ina i polyand a biodiesel-diesel blends [119] 47 Comp ehensi e analysis o he ai quali y impac s o swi ching a ma ine essel om diesel uel o na u al gas [120] 48 Deca bonising he c i ical sec o s o a ia ion, shipping, oad eigh and indus y o limi wa ming o 1.5–2 ◦C[121] 49 Implemen ing ma i ime ba e y-elec ic and hyd ogen solu ions: A echnological inno a ion sys ems analysis [122] 50 Li e-cycle cos assessmen s o di e en powe sys em con igu a ions o educe he ca bon oo p in in he C oa ian sho -sea shipping sec o [123] 51 In es iga ion o mee China II emission legisla ion o ma ine diesel engine wi h diesel me hanol compound combus ion echnology [124] 52 Li e Cycle Assessmen o Al e na i e Ship Fuels o Coas al Fe y Ope a ing in Republic o Ko ea [125] 53 Cha ac e iza ion o Biome hanol-Biodiesel-Diesel Blends as Al e na i e Fuel o Ma ine Applica ions [126] 54 Assessmen o uel cell ypes o ships: Based on mul i-c i e ia decision analysis [127] 55 An e alua ion o he cos -compe i i eness o ma i ime uels—a compa ison o hea y uel oil and me hanol ( enewable and na u al gas) in Iceland [128] 56 Vege able oils as enewable uels o powe plan s based on low and medium speed diesel engines [129] 57 P ocess and Economic E alua ion o an Onboa d Cap u e Sys em o LNG-Fueled CO2Ca ie s [130] 58 Sus ainabili y in Ma i ime Sec o : Was e Managemen Al e na i es E alua ed in a Ci cula Ca bon Economy Pe spec i e [131] 59 The Po en ial Role o Ammonia as Ma ine Fuel-Based on Ene gy Sys ems Modeling and Mul i-C i e ia Decision Analysis [66] 60 Towa ds he IMO’s GHG Goals: A C i ical O e iew o he Pe spec i es and Challenges o he Main Op ions o Deca bonizing In e na ional Shipping [69] 61 LNG and C uise Ships, an Easy Way o Ful il Regula ions-Ve sus he Need o Reducing GHG Emissions [132] 62 En i onmen al and Economic E alua ion o Fuel Choices o Sho Sea Shipping [133] 63 Deca boniza ion o Ma i ime T anspo : Analysis o Ex e nal Cos s [56] 64 Challenges and oppo uni ies o ze o emission shipping in sma islands: A s udy o ze o emission e y lines [134] 65 Hyb id uel cell and ba e y p opulsion sys em modelling and mul i-objec i e op imisa ion o a coas al e y [135] 66 Cha ac e iza ion o pa icula e ma e emi ed by a ma ine engine ope a ed wi h lique ied na u al gas and diesel uels [136] 67 High ene gy densi y s o age o gaseous ma ine uels: An inno a i e concep and i s applica ion o a hyd ogen powe ed e y [137] 68 Pa hways o clima e-neu al shipping: A Danish case s udy [65] 69 Lignocellulosic ma ine bio uel: Technoeconomic and en i onmen al assessmen o p oduc ion in B azil and Sweden [53] 70 Hyb id sola PV/PEM uel Cell/Diesel Gene a o powe sys em o c uise ship: A case s udy in S ockholm, Sweden [36] Ene gies 2022,15, 3571 23 o 30 Table A1. Con . Numbe A icle Ti le Au ho s 71 Pollu ion T adeo s o Con en ional and Na u al Gas-Based Ma ine Fuels [138] 72 Bio uel as an al e na i e shipping uel: echnological, en i onmen al and economic assessmen [4] 73 Fuel demand and emissions o ma i ime sec o in Fiji: Cu en s a us and low-ca bon s a egies [139] 74 How o deca bonise in e na ional shipping: Op ions o uels, echnologies and policies [12] 75 Pe o mance o ma ine diesel engine in p opulsion mode wi h a was e oil-based al e na i e uel [140] 76 Well- o-wheel assessmen o na u al gas ehicles and hei uel supply in as uc u es—Pe spec i es on gas in anspo in Denma k [141] 77 Well- o-wheel g eenhouse gas emissions o ba e y elec ic ehicles in coun ies dependen on he impo o uels h ough ma i ime anspo a ion: A Sou h Ko ean case s udy [142] 78 Al e na i e uels o shipping : Op imising lee composi ion unde en i onmen al and economic cons ain s [143] 79 Techno-economic analysis o a deca bonized shipping sec o : Technology sugges ions o a lee in 2030 and 2040 [52] 80 En i onmen al impac ca ego ies o hyd ogen and ammonia d i en ansoceanic ma i ime ehicles: A compa a i e e alua ion [42] 81 Assessmen o ull li e-cycle ai emissions o al e na i e shipping uels [33] 82 Applica ion o Al e na i e Ma i ime Powe (AMP) Supply o C uise Po [144] 83 Global ene gy scena ios and hei implica ions o u u e shipped ade [145] 84 G eenhouse gas emissions om ships in po s—Case s udies in ou con inen s [34] 85 S a e-o - he-a echnologies, measu es, and po en ial o educing GHG emissions om shipping—A e iew [28] 86 Was e oil-based al e na i e uels o ma ine diesel engines [146] 87 E alua ion o pollu an emissions om wo-s oke ma ine diesel engine ueled wi h biodiesel p oduced om a ious was e oils and diesel blends [147] 88 Sus ainable anspo by use o al e na i e ma ine and a ia ion uels-A well- o- ank analysis o assess in e ac ions wi h Singapo e’s ene gy sys em [148] 89 Reducing GHG emissions om ships in po a eas [32] 90 Emission Reduc ions o Ni ogen Oxides, Pa icula e Ma e and Polycyclic A oma ic Hyd oca bons by Using Mic oalgae Biodiesel, Bu anol and Wa e in Diesel Engine [149] 91 E ec o hyd ogen addi ion on c i e ia and g eenhouse gas emissions o a ma ine diesel engine [150] 92 Impac o Suga cane Renewable Fuel on In-Use Gaseous and Pa icula e Ma e Emissions om a Ma ine Vessel [151] 93 Conside a ions on he po en ial use o Nuclea Small Modula Reac o (SMR) echnology o me chan ma ine p opulsion [37] 94 Vessel op imisa ion o low ca bon shipping [35] 95 E ec s o Biodiesel Blend on Ma ine Fuel Cha ac e is ics o Ma ine Vessels [44] 96 S a egies o p omo ing biodiesel use in ma ine essels [45] 97 Na u al gas as a uel al e na i e o sus ainable domes ic passenge shipping in G eece [152] 98 Emission cha ac e is ics o GTL uel as an al e na i e o con en ional ma ine gas oil [153] Ene gies 2022,15, 3571 24 o 30 Table A1. Con . Numbe A icle Ti le Au ho s 99 Impac o Algae Bio uel on In-Use Gaseous and Pa icula e Emissions om a Ma ine Vessel [154] 100 In es iga ion o engine pe o mance and emissions o a diesel engine wi h a blend o ma ine gas oil and syn he ic diesel uel [155] 101 Ope a ion o Ma ine Diesel Engines on Biogenic Fuels: Modi ica ion o Emissions and Resul ing Clima e E ec s [38] 102 Clima e Impac o Bio uels in Shipping: Global Model S udies o he Ae osol Indi ec E ec [39] 103 Use o soy-de i ed uel o en i onmen al impac educ ion in ma ine engine applica ions [156] Re e ences 1. Si imanne, S.N.; Ho man, J.; Juan, W.; Asa io is, R.; Assa , M.; Ayala, G.; Benama a, H.; Chan el, D.; Ho mann, J.; P em i, A. Re iew o Ma i ime T anspo 2019; UNCTAD: New Yo k, NY, USA, 2019; ISBN 978-92-112858-8. 2. IEA. Commen a y: In e na ional Ma i ime O ganiza ion Ag ees o Fi s Long-Te m Plan o Cu b Emissions. 2018. A ailable online: h ps://www.iea.o g/news oom/news/2018/ap il/commen a y-imo-ag ees- o- i s -long- e m-plan- o-cu b-shipping- emissions.h ml (accessed on 10 Ma ch 2019). 3. Beng sson, S.K.; F idell, E.; Ande sson, K.E. Fuels o sho sea shipping: A compa a i e assessmen wi h ocus on en i onmen al impac . J. Eng. Ma i . En i on. 2015,228, 44–54. [C ossRe ] 4. Kesieme, U.; Pazouki, K.; Mu phy, A.; Ch ysan hou, A. Bio uel as an al e na i e shipping uel: Technological, en i onmen al and economic assessmen . Sus ain. Ene gy Fuels 2019,3, 899–909. [C ossRe ] 5. Kesieme, U.; Pazouki, K.; Mu phy, A.; Ch ysan hou, A. A ibu ional li e cycle assessmen o bio uels o shipping: Add essing al e na i e geog aphical loca ions and cul i a ion sys ems. J. En i on. Manag. 2019,235, 96–104. [C ossRe ] [PubMed] 6. Acomi, N.; Acomi, O.C. Imp o ing he Voyage Ene gy E iciency by Using EEOI. P ocedia-Soc. Beha . Sci. 2014 ,138, 531–536. [C ossRe ] 7. Anˇci´c, I.; Šes an, A. In luence o he equi ed EEDI educ ion ac o on he CO 2 emission om bulk ca ie s. Ene gy Policy 2015 , 84, 107–116. [C ossRe ] 8. Johnson, H.; Johansson, M.; Ande sson, K.; Södahl, B. Will he ship ene gy e iciency managemen plan educe CO 2 emissions? A compa ison wi h ISO 50001 and he ISM code. Ma i . Policy Manag. 2013,40, 177–190. [C ossRe ] 9. IMO. Resolu ion Mepc. 2011. A ailable online: h ps://www.imo.o g/en/KnowledgeCen e/Indexo IMOResolu ions/Pages/ MEPC-2010-11.aspx (accessed on 5 Janua y 2022). 10. Gilbody, S.; Wilson, P.; Wa , I. Bene i s and ha ms o di ec o consume ad e ising: A sys ema ic e iew. Qual. Sa . Heal h Ca e 2005,14, 246–250. [C ossRe ] 11. Pe iˇci´c, T.P.; Tan ee , S. Why Sys ema ic Re iews Ma e —A B ie His o y, O e iew and P ac ical Guide o Au ho s. 2019. A ailable online: h ps://www.else ie .com/connec /au ho s-upda e/why-sys ema ic- e iews-ma e (accessed on 12 Decembe 2021). 12. Balcombe, P.; B ie ley, J.; Lewis, C.; Ska ed , L.; Spei s, J.; Hawkes, A.; S a ell, I. How o deca bonise in e na ional shipping: Op ions o uels, echnologies and policies. Ene gy Con e s. Manag. 2019,182, 72–88. [C ossRe ] 13. Noo , C.W.M.; Noo , M.M.; Mama , R. Biodiesel as al e na i e uel o ma ine diesel engine applica ions: A e iew. Renew. Sus ain. Ene gy Re . 2018,94, 127–142. [C ossRe ] 14. Palocz-And esen, M. Dec easing Fuel Consump ion and Exhaus Gas Emissions in T anspo a ion; Sp inge : Cham, Swi ze land, 2012; ISBN 978-3-642-11976-7. 15. S a is a. Ins alled Powe Capaci y in he Eu opean Union (EU-28) in 2005 and 2017, by Gene a ion Type. 2020. A ailable online: h ps://www.s a is a.com/s a is ics/807675/ins alled-powe -capaci y-eu opean-union-eu-28/ (accessed on 19 Decembe 2021). 16. Maloni, M.; Paul, J.A.; Gligo , D.M. Slow s eaming impac s on ocean ca ie s and shippe s. Ma i . Econ. Logis . 2013 ,15, 151–171. [C ossRe ] 17. Zamia ina, N. Compa a i e O e iew o Ma ine Fuel Quali y on Diesel Engine Ope a ion. P ocedia Eng. 2016 ,134, 157–164. [C ossRe ] 18. Bijle eld, T. F om Lignin o Ma ine Bio uel; Uni e si ei U ech /GoodFuels: U ech , The Ne he lands, 2016. 19. Ve mie e, M.B. E e y hing You Need o Know Abou Ma ine Fuels. Ghen , Belgium. 2021. A ailable online: h ps://www. che onma inep oduc s.com/con en /dam/che on-ma ine/B ochu es/Che on_E e y hingYouNeedToKnowAbou Fuels_ 3_1a_DESKTOP.pd (accessed on 2 Ma ch 2022). Ene gies 2022,15, 3571 25 o 30 20. IMO. Thi d IMO G eenhouse Gas S udy 2014. London—In e na ional Ma i ime O ganiza ion. 2014. A ailable online: h ps://www.imo.o g/en/Ou Wo k/En i onmen /Pages/G eenhouse-Gas-S udies-2014.aspx#:~{}: ex =The%20Thi d%20 IMO%20GHG%20S udy%202014%20used%20quali a i e%20in o ma ion%20 om,e alua e%20global%20domes ic%20 uel% 20consump ion (accessed on 25 Janua y 2022). 21. Olme , N.; Come , B.; Roy, B.; Mao, X.; Ru he o d, D. G eenhouse Gas Emissions F om Global Shipping, 2013–2015. The In e na ional Council on Clean T anspo a ion—ICCT—Whashing on—USA. 2017. A ailable online: h ps://www. heicc .o g/ si es/de aul / iles/publica ions/Global-shipping-GHG-emissions-2013-2015_ICCT-Repo _17102017_ F.pd (accessed on 29 Janua y 2022). 22. Deniz, C.; Zinci , B. En i onmen al and economical assessmen o al e na i e ma ine uels. J. Clean. P od. 2016 ,113, 438–449. [C ossRe ] 23. Jiang, L.; K onbak, J.; Pil, L. The cos s and bene i s o sulphu educ ion measu es: Sulphu sc ubbe s e sus ma ine gas oil. ansp. Res. Pa D T ansp. En i on. 2014,28, 19–27. [C ossRe ] 24. IMO. Adop ion o he Ini ial IMO S a egy on Reduc ion o GHG Emissions om Ships and Exis ing IMO Ac i i y Rela ed o Reducing GHG Emissions in he Shipping Sec o . London—In e na ional Ma i ime O ganiza ion, p. 27. 2018. A ailable online: h ps://un ccc.in /si es/de aul / iles/ esou ce/250_IMO%20submission_Talanoa%20Dialogue_Ap il%202018.pd (accessed on 11 Feb ua y 2022). 25. Ka l, M.; Biese , J.; Geye , B.; Ma hias, V.; Jalkanen, J.-P.; Johansson, L.; F idell, E. Impac o a ni ogen emission con ol a ea (NECA) on he u u e ai quali y and ni ogen deposi ion o seawa e in he Bal ic Sea egion. A mos. Chem. Phys. 2019 ,19, 1721–1752. [C ossRe ] 26. Van, T.C.; Rami ez, J.; Rainey, T.; Ris o ski, Z.; B own, R.J. Global impac s o ecen IMO egula ions on ma ine uel oil e ining p ocesses and ship emissions. T ansp. Res. Pa D T ansp. En i on. 2019,70, 123–134. [C ossRe ] 27. IRENA. A Pa hway o Deca bonize he Shipping Sec o . Abu Dhabi—Uni ed A ab Emi a es. 2021. A ailable online: www.i ena. o g (accessed on 20 Ap il 2022). 28. Bouman, E.A.; Linds ad, E.; Rialland, A.I.; S ømman, A.H. S a e-o - he-a echnologies, measu es, and po en ial o educing GHG emissions om shipping—A e iew. T ansp. Res. Pa D T ansp. En i on. 2017,52, 408–421. [C ossRe ] 29. Psa a is, H.N.; Kon o as, C.A. Balancing he economic and en i onmen al pe o mance o ma i ime anspo a ion. T ansp. Res. Pa D T ansp. En i on. 2010,15, 458–462. [C ossRe ] 30. Web o Science. Web o Science. 2022. A ailable online: h p://login.webo knowledge.com/e o /E o ?E o =IPE o & Pa hIn o=%2F&Rou e URL=h p%3A%2F%2Fwww.webo knowledge.com%2F&Domain=.webo knowledge.com&S c=IP& Alias=WOK5 (accessed on 20 Sep embe 2020). 31. Ampah, J.D.; Yusu , A.A.; A ane, S.; Jin, C.; Liu, H. Re iewing wo decades o cleane al e na i e ma ine uels: Towa ds IMO’s deca boniza ion o he ma i ime anspo sec o . J. Clean. P od. 2021,320, 128871. [C ossRe ] 32. Winnes, H.; S yh e, L.; F idell, E. Reducing GHG emissions om ships in po a eas. Res. T ansp. Bus. Manag. 2015 ,17, 73–82. [C ossRe ] 33. Gilbe , P.; Walsh, C.; T au , M.; Kesieme, U.; Pazouki, K.; Mu phy, A. Assessmen o ull li e-cycle ai emissions o al e na i e shipping uels. J. Clean. P od. 2020,172, 855–866. [C ossRe ] 34. S yh e, L.; Winnes, H.; Black, J.; Lee, J.; Le-G i in, H. G eenhouse gas emissions om ships in po s—Case s udies in ou con inen s. T ansp. Res. Pa D T ansp. En i on. 2017,54, 212–224. [C ossRe ] 35. A ms ong, V.N. Vessel op imisa ion o low ca bon shipping. Ocean Eng. 2013,73, 195–207. [C ossRe ] 36. Ghenai, C.; Be ayeb, M.; B djanin, B.; Hamid, A.K. Hyb id sola PV/PEM uel Cell/Diesel Gene a o powe sys em o c uise ship: A case s udy in S ockholm, Sweden. Case S ud. The m. Eng. 2019,14, 100497. [C ossRe ] 37. Hi da is, S.; Cheng, Y.; Shallc oss, P.; Bona oux, J.; Ca lson, D.; P ince, B.; Sa is, G. Conside a ions on he po en ial use o Nuclea Small Modula Reac o (SMR) echnology o me chan ma ine p opulsion. Ocean Eng. 2014,79, 101–130. [C ossRe ] 38. Pe zold, A.; Laue , P.; F i sche, U.; Hasselbach, J.; Lich ens e n, M.; Schlage , H.; Fleische , F. Ope a ion o ma ine diesel engines on biogenic uels: Modi ica ion o emissions and esul ing clima e e ec s. En i on. Sci. Technol. 2011 ,45, 10394–10400. [C ossRe ] 39. Righi, M.; Klinge , C.; Ey ing, V.; Hend icks, J.; Laue , A.; Pe zold, A. Clima e impac o bio uels in shipping: Global model s udies o he ae osol indi ec e ec . En i on. Sci. Technol. 2011,45, 3519–3525. [C ossRe ] 40. Beng sson, S.; Ande sson, K.; F idell, E. A compa a i e li e cycle assessmen o ma ine uels: Lique ied na u al gas and h ee o he ossil uels. P oc. Ins . Mech. Eng. Pa M J. Eng. Ma i . En i on. 2011,225, 97–110. [C ossRe ] 41. Elgoha y, M.M.; Seddiek, I.S.; Salem, A.M. O e iew o al e na i e uels wi h emphasis on he po en ial o lique ied na u al gas as u u e ma ine uel. P oc. Ins . Mech. Eng. Pa M J. Eng. Ma i . En i on. 2015,229, 365–375. [C ossRe ] 42. Bice , Y.; Dince , I. En i onmen al impac ca ego ies o hyd ogen and ammonia d i en ansoceanic ma i ime ehicles: A compa a i e e alua ion. In . J. Hyd ogen Ene gy 2018,43, 4583–4596. [C ossRe ] 43. Mülle -Casse es, E.; Ca alho, F.; Noguei a, T.; Fon e, C.; Impé io, M.; Poggio, M.; Wei, H.K.; Po ugal-Pe ei a, J.; Rochedo, P.R.; Szklo, A.; e al. P oduc ion o al e na i e ma ine uels in B azil: An in eg a ed assessmen pe spec i e. Ene gy 2021 ,219, 119444. [C ossRe ] 44. Lin, C.Y. E ec s o biodiesel blend on ma ine uel cha ac e is ics o ma ine essels. Ene gies 2013,6, 4945–4955. [C ossRe ]