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Digitalization, artificial intelligence, and awareness of climate change are the driving forces behind the rapid development of the transportation industry. The maritime sector is exploring the applicability of alternative powering options and ways to implement new technologies to increase safety and efficiency, to meet the regulations set by the International Maritime Organisation (IMO) and growth of the seaborne trade. Autonomous shipping is recognized by IMO as a path towards the implementation of new technologies with benefits in terms of safety, costs, and environmental impact. Autonomous shipping aims to operate commercially with a promise of safe, smart, green, and sustainable shipping of the future, while similarly eliminating negative externalities from shipping (noise, pollution, oil spills, congestion in ports, etc.). Based on the literature review, a research gap related to design requirements for power systems of autonomous ships is identified. Although the literature indicates that autonomous vessels are expected to be as safe as the conventional ones, it is obvious that absence of crew leads to savings in operative costs, but at the same time it significantly reduces possibility for corrective maintenance during the voyage. Therefore, it is necessary to analyse key activities of the crew related to the operation of ship power system and to define effect of lack of crew on the safety level. The aim of this paper is to analyse differences between power systems of conventional and autonomous ships and their role in the safety assessment, as well as to provide a set of solutions for successful transition from manned to unmanned ship power system.

In order to deal with the decarbonisation of the transport sector, many policies suggest the application of alternative fuels with an emphasis on the electrification, an increase in the energy efficiency of transportation modes and a shift of freight and passenger transport from road transportation to other modes of land transport such as inland waterway transport. The vessels engaged in the inland waterway transport are often outdated, powered by low-energy efficient diesel engines, operating near populated areas and thus directly impair the air quality of the nearby population. Therefore, their energy efficiency and environmental friendliness need to be improved. Furthermore, energy efficiency and environmental friendliness assessment of ships with alternative power systems represent a special issue, since such mathematical models regularly consider power systems that use fuel with carbon content only. In this paper, the retrofitting of different types of vessels (cargo ship and passenger ship) with alternative power systems (powered by electricity, methanol, natural gas hydrogen and ammonia) is considered, while the diesel power system configuration represents a baseline scenario. Their energy efficiency and environmental friendlies are assessed, considering their annual life-cycle emissions and benefit to the society, by means of the mathematical model recently published in the literature and applied to short- sea vessels only. Its applicability to other transportation modes/ship types is confirmed and differences in energy efficiency and environmental friendliness of different power system alternatives are outlined.

The emissions released due to the combustion of fossil fuels in marine engines negatively affect the environment and human health. This impact of shipping is more pronounced when the ships operate near populated areas and spend much time in ports, and in that way, directly impair the air quality of the local population. These ships are usually engaged in the short-sea shipping and inland navigation sector. In this doctoral dissertation, the focus is put on the Croatian short-sea shipping and inland navigation fleets, which mainly include outdated ships with low energy efficiency. Their design methods either did not include energy efficiency criteria or included them according to relatively old and simple models and criteria. These fleets need to adapt to current environmental trends, whereby it is necessary to choose a set of appropriate technical and operational measures that would be cost-effective for the current fleet situation and market circumstances. In this research, the investigation of applicability and availability of alternative power systems onboard considered ships is performed. By comparing the different alternatives based on their environmental impact and economic performance, obtained by performing Life-Cycle Assessments and Life-Cycle Cost Assessments, the set of appropriate alternatives that satisfy both criteria is identified. To investigate the energy efficiency of the ships powered by alternative power systems, the mathematical model for simultaneous assessment of ship energy efficiency and environmental friendliness is formulated, which can be applied not only to diesel-powered ships but to a range of alternative powering options. The final step in the research was the development of the design procedure for the power systems of short-sea shipping and inland waterway vessels, with higher energy efficiency and lower overall costs than the existing solutions. The developed procedure is tested for the ships engaged in the short-sea shipping fleet, and in most cases, the results indicated full electrification with only a battery as the optimal solution for the replacement of the diesel power system configuration of considered ships. Although the Croatian short sea-sea and inland waterway fleets are taken as test cases, the developed methodology is generally applicable if a set of input data on fleet technical and operational properties and corresponding fuel cycles is known. Ispušni plinovi nastali izgaranjem fosilnih goriva u brodskim motorima smatraju se glavnim uzrokom onečišćenja zraka u pomorskom okolišu. U literaturi koja se bavi ovom problematikom razlikujemo štetne emisije dušikovih oksida (NOX), sumporovih oksida (SOX), ugljikovog monoksida (CO), lebdećih čestica te emisije stakleničkih plinova (ugljikov dioksid (CO2), metan (CH4), didušikov oksid (N2O)) [1]. Njihova prisutnost u atmosferi negativno utječe na okoliš i ljudsko zdravlje [2], što je posebice izraženo kod brodova priobalne i unutarnje plovidbe, koji provode razmjerno puno vremena u blizini naselja [3], [4]. Zahtjevi vezani uz zaštitu okoliša prisilili su pomorski sektor na povećanje energetske učinkovitosti, uz pretpostavku da navedeno povećanje vodi k smanjenju utjecaja pomorskog prometa na okoliš. Odbor za zaštitu pomorskog okoliša (eng. Marine Environment Protection Committee, MEPC) pri Međunarodnoj pomorskoj organizaciji (eng. International Maritime Organization, IMO) donio je rezoluciju u kojoj je dodano poglavlje o energetskoj učinkovitosti brodova [5], a prema kojoj brodovi koji sudjeluju u međunarodnoj plovidbi trebaju imati Međunarodni certifikat energetske učinkovitosti. Za njegovo izdavanje brodovi trebaju udovoljiti zahtjevima Projektnog indeksa energetske učinkovitosti (eng. Energy Efficiency Design Index, EEDI) i imati Brodski plan upravljanja energetskom učinkovitošću (eng. Ship Energy Efficiency Management Plan, SEEMP). EEDI predstavlja tehničku mjeru energetske učinkovitosti i izražava se kao omjer emisije CO2 i gospodarskog učinka broda [6]. Pri tome valja naglasiti da je riječ o projektnoj veličini koja se analizira za jednu radnu točku, budući da je vezana za projektnu nosivost i brzinu broda, koje se u njegovoj eksploataciji pojavljuju vrlo rijetko. Projektni indeks energetske učinkovitosti određuje se za brodove veće od 400 GT u međunarodnoj plovidbi, dok za brodove priobalne plovidbe (angažirane u teritorijalnim vodama jedne države) i brodove unutarnje plovidbe trenutno ne postoji zakonska regulativa kojom bi se analizirala energetska učinkovitost. Spomenuti model nije izravno primjenjiv na brodove koji bi podrazumijevali korištenje alternativnih izvora energije ili za potpuno električne brodove. Povećanje energetske učinkovitosti brodova te smanjenje njihovih emisija, posebice CO2 koji je glavni staklenički plin čija povećana koncentracija u atmosferi doprinosi globalnom zatopljenju, može se postići primjenom određenih tehničkih i operativnih mjera [7]. Studije ukazuju da je najbolja mjera zamjena konvencionalnog brodskog energetskog sustava s alternativnim. Smanjenje emisija je važno i za hrvatske flote priobalne i unutarnje plovidbe, koje čine relativno stari brodovi niske energetske učinkovitosti. Navedene flote trebaju se prilagoditi suvremenim ekološkim trendovima, pri čemu je potrebno odabrati skup odgovarajućih mjera koje bi za odgovarajuće stanje flote i tržišne okolnosti bili isplative. U ovom radu razvijen je projektni postupak za brodske energetske sustave visoke razine energetske učinkovitosti, uzimajući u obzir specifične eksploatacijske zahtjeve priobalne i unutarnje plovidbe u cjeloživotnom okruženju i tržišne zakonitosti u Republici Hrvatskoj. Prvi korak istraživanja obuhvatio je analizu tehničkih značajki i načina korištenja brodova priobalne i unutarnje plovidbe (s naglaskom na brodske energetske sustave). U drugom koraku provedena je analiza dostupnosti alternativnih goriva (prirodni plin, električna energija, metanol, amonijak, vodik itd.) na području Republike Hrvatske. Njihova primjena na odabranim brodovima razmatranih flota istražila se procjenom životnog ciklusa (eng. Life-Cycle Assessment, LCA) brodskog energetskog sustava na okoliš te procjenom troškova životnog ciklusa (eng. Life Cycle Cost Assessment, LCCA). LCA ocjenjuje utjecaj brodskog energetskog sustava na okoliš kroz količine emisija koje se ispuštaju tijekom cijelog životnog vijeka energetske konfiguracije, odnosno od izrade dijelova energetske konfiguracije (baterija, motor, gorivni članak i sl.), proizvodnje izvora energije (gorivo, struja i sl.) do njegove primjene na brodu. Utvrđivanje održivosti i isplativosti alternativnih brodskih energetskih sustava postiže se provođenjem LCCA koja uzima u obzir troškove ulaganja, goriva, održavanja i zamjene opreme tijekom životnog vijeka proizvoda. Usporedba LCA i LCCA rezultata različitih goriva dovela je do identifikacije seta alternativnih tehnologija koje su primjenjive na odabranim brodovima priobalne i unutarnje flote Republike Hrvatske, a koji imaju manje cjeloživotne troškove i emisije od postojećih konvencionalnih rješenja. Analiza je posebno istaknula potpunu elektrifikaciju samo s baterijom, kao i primjenu metanola, kao izvedive alternative koje zadovoljavaju ekološke i ekonomske kriterije. Treći korak u ovom istraživanju predstavlja definiranje indeksa energetske učinkovitosti koji istodobno u obzir uzima energetsku učinkovitost broda i ekološku prihvatljivost, a može se primijeniti ne samo na brodove s pogonjene dizelskim motorom već i na niz alternativnih opcija napajanja. Uključivanje LCA i LCCA u definiciju novog indeksa energetske učinkovitosti predstavlja važan iskorak u poboljšanju postojećeg modela. Naposljetku, razvijen je projektni postupak kojim je moguće odabrati prikladne konfiguracije brodskih energetskih sustava brodova priobalne i unutarnje plovidbe s alternativnim izvorima energije, koji imaju povoljnije vrijednosti indeksa energetske učinkovitosti u odnosu na postojeća rješenja. Istraživanja provedena u ovom doktorskom radu vezana su za Uspostavni istraživački projekt „Zeleni modularni putnički brod za Mediteran“ (UIP-2017-05-1253), financiran od Hrvatske zaklade za znanost, a zaposlenje doktorandice financirano je također od Hrvatske zaklade za znanost iz „Projekta razvoja karijera mladih istraživača – izobrazba novih doktora znanosti“ u okviru natječaja DOK-01-2018. a) Ciljevi i hipoteze Glavni cilj ovog istraživanja je razviti projektni postupak za brodske energetske sustave visoke razine energetske učinkovitosti, uzimajući u obzir specifične eksploatacijske zahtjeve priobalne i unutarnje plovidbe i tržišne zakonitosti u Republici Hrvatskoj. Projektni postupak podrazumijeva i vezan je uz ostvarenje drugih ciljeva rada, odnosno definiranje projektnog indeksa energetske učinkovitosti za brodove priobalne i unutarnje plovidbe koji je primjenjiv za brodske energetske sustave s alternativnim izvorima energije, te ujedno i istraživanje dostupnosti alternativnih energetskih rješenja na području Republike Hrvatske i njihovu primjenjivost u hrvatskoj floti priobalne i unutarnje plovidbe. Prva hipoteza na kojoj se temelji ovo istraživanje je da je moguće definirati projektni indeks energetske učinkovitosti za brodove priobalne i unutarnje plovidbe, koji uključuje više radnih točaka (različite brzine plovidbe, a posljedično i radne režime kojima je podvrgnut brodski energetski sustav) i primjenjiv je za energetske sustave koji uključuju alternativne izvore energije. Druga hipoteza je da moguće je razviti projektni postupak za energetske sustava brodova priobalne i unutarnje plovidbe, koji će imati veću energetsku učinkovitost i manje ukupne troškove od postojećih rješenja. b) Znanstveni doprinosi Znanstveni doprinosi ovog rada su u području tehničkih znanosti, znanstvenom polju brodogradnje, a temelj im predstavlja formulacija indeksa energetske učinkovitosti i ekološke prihvatljivosti brodova za priobalnu i unutarnju plovidbu u Republici Hrvatskoj s proizvoljnim udjelom alternativnih izvora energije. Dakle, definiran matematički model istodobno procjenjuje energetsku učinkovitost broda i ekološku prihvatljivost, a može se primijeniti ne samo na brodove pogonjene dizelskim motorom već i na niz alternativnih opcija napajanja. Predstavljeni model je prvi znanstveni doprinos ovog rada i nastao je kao rezultat proširenja modela iz dostupne literature koji podrazumijevaju isključivo pogonske sustave temeljene na dizelskim motorima kao prvopokretačima. Brodovi razmatranih flota uglavnom su zastarjeli, pogonjeni dizelskim motorima razmjerno niske energetske učinkovitosti . Zamjena brodova novima ili zamjena njihovog energetskog sustava alternativnim otvara mogućnost za implementaciju inovativnih i zelenih tehnologija koje će zadovoljiti ekološke propise i smanjiti izravan utjecaj na lokalno stanovništvo. Mogućnost uvođenja različitih politika penalizacije emisija koje nastaju izgaranjem fosilnog goriva u brodskim motorima djeluje kao poticaj brodovlasnicima i prijevoznicima na primjenu alternativnih brodskih energetskih sustava čije korištenje na brodu rezultira manjim emisijama u usporedbi s postojećim energetskim sustavom ili ih u eliminira. Kako bi ispitao njihov utjecaj na okoliš, emisije razmatranih energetskih sustava treba istražiti s cjeloživotnog stajališta pomoću LCA, uzimajući u obzir emisije ciklusa goriva (od vađenja sirovine, njenog prijevoza do proizvodnog postrojenja, do proizvodnje samog goriva te njegove distribucija do crpke), upotreba goriva na brodu te proizvodnja glavne opreme sustava. Uz ispitivanje utjecaja na okoliš, važno je istražiti i isplativost brodskih energetskih sustava pomoću LCCA, uzimajući u obzir troškove investicije, održavanje, goriva i zamjene opreme tijekom eksploatacije broda. Provođenjem LCA i LCCA različitih brodskih energetskih sustava analizirala se njihova primjena u hrvatskoj floti priobalne i unutarnje plovidbe. Identificiran je skup alternativnih energetskih rješenja koja imaju manje cjeloživotne emisije i cjeloživotne troškove od postojećeg brodskog energetskog sustava, što je ujedno i drugi doprinos ovog doktorskog rada. Treći doprinos ovog rada je projektni postupak za energetske sustave visoke razine energetske učinkovitosti za brodove koji relativno često mijenjaju operativne režime, kakvi su dominantno zastupljeni u hrvatskoj priobalnoj i unutarnjoj plovidbi. Provođenjem LCA i LCCA različitih energetskih sustava te usporedba njihovih vrijednosti formuliranog indeksa, projektni postupak identificira optimalno rješenje koje ima višu energetsku učinkovitost, manje emisije i manje troškove od postojećih rješenja. Iako je rad usmjeren na brodove priobalne i unutarnje flote Republike Hrvatske, razvijeni projektni postupak, formulirani indeks energetske učinkovitosti primjenjiv je i za alternativne elektroenergetske sustave, kao i modeli ekonomske analize i analize utjecaja na okoliš alternativnih rješenja općenito su primjenjivi na sektore priobalne i unutarnje plovidbe drugih zemalja ako je skup specifičnih ulaznih podataka dostupan.

Reduction of ship emissions is nowadays one of the most important research topics in maritime sciences. This is particularly true for decarbonization, where different technical and operational measures, as well as various business strategies, are being investigated to reduce carbon dioxide (CO2) emissions. Fishing vessels generally do not belong to these categories, but their effect on humans and environment is very important since fishing operations are mainly performed in coastal waters. On the other hand, fishing vessels are mainly equipped with an outdated low-efficient diesel engines resulting in relatively high emissions. In Croatia, fishing has a long tradition and the indented coast of the Adriatic, as well as the rich sea, have enabled the coastal population to engage in fishing for generations. The Croatian fishing fleet includes 5% purse seiners, which make the largest amount of catches. This paper investigates the possibilities of implementing alternative fuels in power systems of purse seiners and their effect on the reduction of CO2 emissions. 5-year data on fuel consumption and catch of purse seiners with different technical characteristics from the Croatian fishing fleet are used to calculate the level of emission release of possible solutions. Life-Cycle Assessment (LCA), which includes the ship operation and the process of fuel supply, is used to compare a diesel-powered configuration with alternative ones. In conclusion, a complete assessment of the efficiency of alternative fuels is given and guidelines for further research are proposed.

The maritime sector is exploring the applicability of alternative powering options and ways to implement new technologies to increase safety, efficiency, and autonomy of ship power systems. The technological development of power systems, their complexity, and high costs of their malfunction or downtime have led to employment of different approaches in safety engineering. In order to reduce hazards and failures in ship operation, shipbuilders use several methods during design phase to identify, investigate and manage all safety concerns. For this purpose, there is range of methods, as for instance Fault Tree Analysis (FTA), Event Tree Analysis (ETA), Failure Mode Effects Analysis (FMEA), and Failure Mode, Effects and Criticality Analysis (FMECA), which can be used separately or combined. This paper reviews these methods with their advantages and limitations in their application to risk assessment of ship power systems.

In recent years, the ship maintenance has significantly evolved to increase both the safety and environmental protection. Bearing in mind that the number of crew and engineers on board has been reduced drastically and that maintenance requires significant effort (manpower, time, money, etc.) the development of a maintenance plan came to be useful. Ship maintenance accounts for 20-30% of a ship’s operational costs and is related to unexpected breakdowns, repairs, loss of operational availability, and consequently revenue. Generally, maintenance procedures can be divided into corrective, preventive, condition based, and reliability centred maintenance. Preventive and condition based maintenance procedures are under continuous development by employing various tools and technological advancements aiming to detect upcoming failures before they occur thus increasing reliability and reducing costs. This paper brings out an overview of recent developments in maintenance procedures and outlines their advantages and drawbacks.

Demands for aquaculture products are ever rising at global level and are resulting in greater investments in the development of efficient and sustainable mariculture farms. However, these developments imply increase in energy needs, which are nowadays mainly ensured from fossil fuels. This work provides an overview of environmentally friendly energy alternatives that are being developed under the Research Center for Intelligent, Inovative, Enviromentally Friendly and Sustainable Mariculture (INTEL-MARIC) that has been founded at UNIZAG FSB. Basic goals, research strategy and activities of INTEL-MARIC are illustrated. Moreover, this work represents extension of investigations presented Korican et al. (2020, 2022) which resulted in alternative configurations of aquaculture systems that enable integration of high share of renewable energy sources. Previous works were limited to the evaluation of carbon footprint, while this one also includes evaluation of other polutants originating mainly from the internal combustion engines onboard aquaculture support vessels as for instance NOx, SOx, PM, etc. Alternative powering options for the complete aquaculture system were evaluated in order to identify those with minimum environmental footprint, simultaneously taking into account costs and environmental regulations. Above developments are illustrated for an aquaculture farm in Croatia, but they are generally applicable if the relevant set of input data is known. Further investigations will include feasibility of the same aquaculture system at different locations along the Adriatic coastline, that have different wind and insolation profiles, and consequently different potential of integration of high share of RES.

Rapid technological development, wireless communication, and monitoring, growing environmental awareness, alternative fuels, and harsher regulations are continuously pressuring maritime transportation and shipbuilding. The maritime sector is exploring ways to reduce cost and emissions but at the same time to increase safety and energy efficiency. Autonomous shipping is an emerging topic, where technical, economic, safety, and environmental aspects are still not mature enough to significantly increase the percentage of autonomous vessels in the global fleet. The reduced crew onboard brings savings and a lower risk of human-induced errors that can lead to human casualties and environmental disasters. However, autonomous vessels monitored from the shore require a high-quality and reliable communication system. The technologies needed for autonomous navigation already exist and it is necessary to find the optimal way to combine their safety, reliability, feasibility, and cost- effectiveness. Short-sea shipping is an ideal candidate for developing and testing new technologies due to shorter routes, low energy demand, and frequent port calls. The Croatian part of the Adriatic coastline with numerous islands and developed tourism activity is extremely sensitive to congestion and marine pollution. This paper presents the analysis of Croatian maritime accident reports to assess whether the accident would have happened if the ship had been autonomous, and once the accident had happened - would its consequences have been different.

Climate strategies and emission regulations are pushing the shipping industry towards the implementation of various decarbonization measures, among which the replacement of conventional marine fuels with alternative and cleaner one is highlighted as the most promising option to achieve emissions reduction in the shipping sector. Although many alternative marine fuels have lower carbon, nitrogen and sulphur content, compared to heavy fuel oil (HFO) or marine diesel oil (MDO), and their use as ship fuels results in lower tailpipe emissions, their environmental performance needs to be investigated from the life-cycle point of view. In this paper, the application of methanol is investigated since it is a widely investigated alternative fuel. Its environmental impact is analysed with Life-Cycle Assessment, where the CO2, NOX and SOX emissions released through the life-cycle of the different types of methanol (i.e. fossil methanol produced from natural gas, and six types of methanol produced from different biomass (willow, switchgrass, forest residue, corn stover, miscanthus and poplar)) implemented in a ship power system are investigated and compared to the life-cycle emissions of the diesel-powered ship. The results of the paper are illustrated on a ro-ro passenger ship engaged in the Croatian short-sea shipping sector, and they indicated that even fossil methanol achieve emission reduction by 31% of CO2, 80% of NOX, and 87% of SOX, compared to the emissions released from the diesel-powered ship. However, the most environmentally friendly fuel is the bio-methanol produced from forest residue, which results in 94% lower CO2 and 99% lower NOX and SOX emissions than emissions released from the diesel- powered ship.

Coastal shipping is nowadays very important research topic, where the emphasis is mainly on the improvement of ship energy efficiency (reduction of fuel consumption) and its environmental performance. In line with this, the ship design procedure is being more complicated aiming to offer competitive products with high level of comfort for both crew and passengers, low operative costs and minimum environmental footprint. Moreover, special attention is nowadays paid to the increase of ship autonomy. This paper deals with technical properties of existing small passenger vessels in countries in the Mediterranean basin and future market needs for these vessels considering more stringent habitability criteria and emission reduction targets. Overview of ship technical properties has been made from data available in the IHS Fairplay database, where number of passengers (ship capacity) is considered as a key design feature. Finally, guidelines for the design of small passenger ships for Mediterranean are drawn, where modular concept is proposed. The concept considers ship as an assembly of different virtual modules that are predefined in order to satisfy future targets, bearing in mind their cost-effectiveness.

Environmental regulations and emissions targets are pushing the shipping industry towards the implementation of alternative decarbonization measures. Among them, the application of zero- emission solutions, such as the use of hydrogen and electricity, are highlighted. Although with their implementation, the exhaust gas while the ship is operating is absent, their environmental performance needs to be investigated from the life-cycle point of view. Therefore, the Life-Cycle Assessment (LCA) is performed, where the emissions released through the life-cycle of the power system with hydrogen and electricity are investigated and compared to the diesel power system configuration. The comparison indicated that the hydrogen produced through the process of electrolysis (green hydrogen) is the best ecological solution with respect to all investigated emission products, while the second-most environmental friendly zero-emission alternative is the full electrification of a ship with a Lithium-ion battery.

Reduction of costs and an increase in safety are permanent and very often contradictory goals of the maritime sector. Autonomous vehicles appear in all forms of land transport, aerospace engineering, as well as in marine transportation. Autonomous shipping is an emerging topic, where technical, economic, safety and environmental aspects are still not mature enough to significantly increase the percentage of autonomous vessels in the global fleet. This paper deals with the analysis of the economic benefits of autonomous container vessels, by comparing their costs with the costs of the conventional one. The container ship is selected as a test case because of its relatively simple cost assessment scheme and relatively uniform operative profile compared to other ship types (coastal passenger vessels, fishing vessels, etc.). A simplified ship cashflow model is established, where the classical cost scheme (including capital costs, operative costs, voyage costs, etc.) is extended by the potential carbon allowance. Although carbon allowance policies are not introduced into the marine sector, for the time being, the overall design procedure for the ship of the future requires the implementation of a next-generation regulatory framework. Bearing in mind existing regulations set by International Maritime Organization related to Energy Efficiency Design Index, it is important to investigate simultaneously the effect of an increase of ship autonomy both on its environmental and economic performance. The analysis is performed for the Asia-Europe shipping route, where obtained results indicate economic benefits of autonomous container ships over the conventional ones, under the set of analysis assumptions. The presented model can serve as the basis for the investigation of autonomous ships with more complex design and operative features, like short-sea vessels, where a more complex cost assessment scheme will be needed.

Reduction of fuel consumption and lowering harmful gas emissions belong to the category of most important research topics in marine transportation. The former issue is important for all ships, while the latter one is even more emphasized for the vessels operating within highly inhabited areas like short-sea or inland waterway vessels. The International Maritime Organization aims to reduce total annual greenhouse gas emissions from international shipping by 50 % by 2050 and to reduce the average carbon intensity (CO2 per ton- mile) by a minimum of 40 % by 2030, and 70 % before 2050, all compared to the 2008 levels [1]. This paper considers technical, environmental and economic aspects of implementation of alternative power system configurations in the Croatian coastal shipping sector with respect to short- and long-term emission reduction targets, where existing diesel engine-powered Ro-Ro passenger vessel is taken as a test case. In this sense, operating profile of the considered ship and its power needs are analysed and viability of use of alternative powering options is considered [2, 3]. While the environmental analysis is performed it Life-Cycle Assessment (LCA), Figure 1, the economic analysis is performed with Life-Cycle Cost Assessment (LCCA), Figure 2. In the analysis, the features of the Croatian energy sector are taken into account. Appropriate sensitivity studies of economic indicators with respect to input parameters are performed. The obtained results show that beside reduction in greenhouse and harmful emissions, the electrification of the considered ship leads to the financial savings over its lifetime. Although Croatian case study is considered, the methodology is applicable generally, but the conclusions will be case-specific, depending on the ship technical and exploitation performance and characteristics of energy sector of the considered country.

Energy efficiency and environmental performance become important aspects of all transportation branches involving diesel engines as prime movers. The same is for the fishing sector, where besides ensuring sustainability, one seeks for minimizing operative costs through the reduction of fuel consumption. Ship emissions can be determined at different levels of complexity and accuracy, i.e. by analysing ship technical data and assuming its operative profile, or by direct measurements of key parameters and their postprocessing to obtain exact amounts of exhaust gases. This paper deals with the analysis of the environmental footprint of a fishing trawler operating in the Adriatic Sea, including both Well-to-Pump (WTP) and Pump- to-Wake (PTW) phases of the fuel. Based on the data on fuel consumption and exploitation scenarios of the considered ship, provided by the ship-owner, the ship emissions have been determined. Also, a review of different emission reduction technologies has been provided Among various alternatives to diesel engine powered fishing vessels a hydrogen-powered option is considered, where the obtained results show that hydrogen is rather far from application in the Croatian fishing sector.

Increased social awareness on the greenhouse gases led to climate agreements setting their strict reduction targets. In order to achieve decarbonization of the shipping industry, some technical measures can be applied, such as replacement of classical ship power system with diesel engine as a prime mover with some alternative solution. This paper investigates the applicability of alternative power system configurations that can be implemented on board passenger and cargo ships from Croatian inland waterway fleet. The environmental impact of three different potential power system configurations (diesel engine-powered ship, battery-powered ship and photovoltaic cells- battery-powered ship) was investigated through the Life Cycle Assessment (LCA) by means of GREET 2019 software. The comparison identified the photovoltaic cells- battery-powered ship configuration as the most environmentally friendly power system configuration.

Reductions of environmental footprint and lifetime costs are nowadays key aspects of most of human activities. Such concerns are also present in the aquaculture sector which involves the cultivation of aquatic organisms as well as all activities related to their processing, seeking to ensure sustainable growth. This paper deals with the environmental and economic aspects of aquaculture systems (involving aquaculture farms and relevant farm vessels) with a high share of renewable energy sources (RES). The energy needs of a typical aquaculture system are identified and Life Cycle Assessments (LCAs) of different power system configurations are performed. These configurations are also compared from the economical viewpoint, by the Life Cycle Cost Assessment (LCCA). Electrification of farm vessels is recognized as a key solution to reduce both the environmental footprint and operating costs. However, as shown by LCA, due to specific operating profile of farm vessels their energy needs can not be completely covered by RES, since an amount of electricity supplied from the national grid is needed. Therefore, the share of renewables will be dependent on the percentage of RES in the energy mix of the specific location of the aquaculture system. The LCCA analysis has shown that this form of integration requires larger investment which, if an unfavourable form of RES is chosen, may cause financial losses.

Reduction of fuel consumption is a permanent research goal in all kinds of transportation. Moreover, in the last decade marine transportation is strongly influenced by the new regulatory framework for marine pollution that motivates investigation of alternative powering options for ships, offering lower emissions and lifetime costs. This work analyses current regulations on ship emissions associated with long term emission reduction goals, mathematical models to evaluate ship energy efficiency as well as technical and operative measures to meet ever stricter requirements [1, 2]. Mathematical models for life-cycle assessments (LCAs) of ship emissions and life-cycle cost assessments (LCCAs) are applied for several ships operating in coastal waters and inland waterways that are powered by alternative fuels and with different power system configurations [3, 4]. Electrification of ships is recognized as a promising option to reduce both lifetime emissions and total lifetime costs. However, additional research efforts are needed to make energy storage (batteries) and conversion technologies cheaper and applicable to long-distance shipping.

Reduction of fuel consumption and lowering harmful gas emissions are among the most important research topics in marine transportation. The latter particularly refers to the vessels that operate within highly inhabited areas like short- sea vessels. This paper deals with the techno- economic assessment of the implementation of renewable energy sources in the short-sea shipping sector, where Croatian ro-ro passenger fleet is taken as a test case. In this sense, the aim of the paper is to identify preferable power system configuration that reduces ship emissions (CO2, NOX, SOX, particulates) at acceptable costs. Firstly, realistic operating profile of ro-ro passenger ships is analysed and their annual emissions are evaluated by assessing total fuel consumption and multiplying it by relevant emission factors. Secondly, renewable energy potential in the Adriatic Sea and Croatian energy mix are reviewed. Third, the techno- economic analysis of conventional power systems with a diesel engine as a prime mover, and proper alternatives is done. Finally, it is found that electrification of short-sea shipping sector is recognized as a promising option to reduce environmental footprint and operative costs of the ship over its lifetime.

Most of human activities are strongly influenced by stringent environmental legislation prescribing reduction of their environmental footprint. In this sense, different technical and operational measures, alternative fuels as well as alternative power systems are investigated, where their pricing is regularly recognized as a key issue. This investigation deals with reductions of environmental footprint and lifetime costs in the aquaculture sector which involves different activities dedicated to growing of aquatic organisms and their after- treatment. In this sense, environmental and economic aspects of aquaculture systems (involving aquaculture farms and relevant farm vessels) with a high share of renewable energy sources (RES) are analysed, where typical aquaculture farm located in Croatia is taken as a test case. The energy needs of the system are evaluated and Life Cycle Assessments (LCAs) of different power system configurations are done. Life Cycle Cost Assessment (LCCA) is performed to evaluate different power system configurations from the environmental point of view. The results indicate that the electrification of farm vessels is a key solution to reduce both the environmental footprint and operating costs. Based on the specific operating profile of farm vessels, it is likely that energy needs will not be fully covered by just one type of RES. A combination of several forms of RES or an amount of electricity supplied from the national grid is needed.

In the current practice, ship design is generally approached with the aim of keeping building-cost at the minimum, often forcing low-cost designs and low value-added market solutions. This is particularly true for small- size passenger vessels designed for short-sea shipping which are usually built by small shipyards which cannot sustain high costs of innovation and investments in education and research. In addition, unlike other transport modes, vessels are generally produced in small series and the investment cost has a strong impact on the initial vessel cost. Therefore, ships are often based on previous concepts and designs with essentially no modernization, thus leading to poor energy efficiency improvements, high vessel life-cycle costs and significant environmental impact. The new regulations in shipping sector demand energy efficiency improvements, but the stakeholders lack in providing support in achieving these requirements. In order to increase competitiveness, changes are required not only in individual stages of a shipbuilding process, but integrally throughout the production process. Conventional design and production paradigm can be changed by developing a modular concept in ship design. The aim of this paper is to determine the potential to reduce environmental pollution from ships and thereby the externalities by applying modular concept for small passenger ships in the Mediterranean. This new concept for a high-efficiency passenger vessel class can facilitate the design process, reduce the initial cost of more technologically advanced vessels by allocating innovation costs to units in a much larger series, and thus prove as a viable and sustainable alternative.

Studija obuhvaća analizu prethodne i trenutno važeće regulative za plovila unutarnje plovidbe u Republici Hrvatskoj i odabranim stranim zemljama (prema javno dostupnim podacima), s naglaskom na uvjete i načine oslobađanja od plaćanja trošarina na energente, te odgovarajuću komparativnu analizu. Obrađeni su podaci o floti unutarnje plovidbe, dostavljeni od naručitelja, pri čemu su plovila grupirana u odgovarajuće kategorije prema namjeni i tehničkim značajkama. Na temelju dostavljenih podataka, provedena je statistička obrada deklariranih podataka o potrošnji goriva i usporedba s dodijeljenim/odobrenim količinama. Prema tehničkim podacima flote i eksploatacijskim režimima predviđena je stvarna potrošnja goriva analiziranih plovila, odnosno referentne vrijednosti s obzirom na gospodarski učinak. Naposljetku, dan je fizikalno utemeljeni prijedlog korekcije postojećih kvota za oslobođenje od plaćanja trošarina.