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This paper provides an in-depth analysis of alternative fuels, including liquefied natural gas (LNG), hydrogen, ammonia, and biofuels, assessing their feasibility based on operational requirements, availability, safety concerns, and the infrastructure needed for large-scale adoption. Moreover, it examines hybrid and fully electric propulsion systems, considering advancements in battery technology and the integration of renewable energy sources, such as wind and solar power, to further reduce SOV emissions. Key findings from this research indicate that LNG serves as a viable short- to medium-term solution for reducing GHG emissions in the SOV sector, due to its relatively lower carbon content compared to MDO and HFO. This paper finally insists that while LNG presents an immediate opportunity for emission reduction in the SOV sector, a combination of hydrogen, ammonia, and hybrid propulsion systems will be necessary to meet long-term decarbonisation goals. The findings underscore the importance of coordinated industry efforts, technological innovation, and supportive regulatory frameworks to overcome the technical, economic, and infrastructural challenges associated with decarbonising the maritime industry. [ABSTRACT FROM AUTHOR]

The Turkish Straits are critical waterways connecting the Mediterranean and the Black Sea. About 38,552 and 43,343 ships pass through the Strait of Istanbul and Strait of Canakkale annually, respectively, and their emissions into the air pose a threat to the regional and global environment, as well as to the people of the region. Herein, the effects of the declaration of the Sea of Marmara as an emission control area and the use of alternative fuels by ships on emission formation were examined. For this purpose, the data of the ships passing through the Turkish Straits were obtained, the engine powers were calculated based on the gross registered tonnage values of these ships, and the emission values were reached. Declaring the Sea of Marmara as an emission control area provides an 80% and 76% reduction in sulfur and nitrogen oxides, respectively. Carbon emissions remained the same. The use of liquefied natural gas dramatically reduces carbon emissions. Alternative fuels, especially liquefied natural gas, effectively reduce sulfur oxide emissions. Despite these positive effects, there seem to be many years ahead of the widespread use of alternative fuels due to the lack of technical and economic infrastructure. Thus, the declaration of the Sea of Marmara as an emission control area will positively affect both the population in the region and the region's environment. [ABSTRACT FROM AUTHOR]

The continuous increase in global maritime freight transport has led to an increase in emissions. The port of Heraklion was selected as a case study to investigate the environmental impact of shipping in wider areas. Two different maritime fuels were examined: the conventional maritime fuel, marine diesel oil (MDO), and an alternative maritime fuel, liquified natural gas (LNG). To carry out this study, real data from the port of Heraklion, the Lloyd's Register Fairplay (LRF) Sea-Web database, and literature reviews were used. The bottom-up method was adopted for data processing. The results of this study demonstrate that alternative maritime fuels, such as LNG, could drastically reduce SO2, NOx, PM, and CO2 emissions. [ABSTRACT FROM AUTHOR]

Increasing amount of shipboard emissions, and emission regulations entered into force encourage emission reduction technologies to be developed, and new methods to be used. Alternative fuel use as a fuel on marine diesel engines is one of the new methods to reduce shipboard emissions. Methanol and ethanol can be used as a liquid fuel or liquefied natural gas and hydrogen can be used as a gaseous fuel on ships. Aim of this study is to make scientific comparison of alternative fuels which can be used at ships. The environmental and economical performance of methanol, ethanol, liquefied natural gas, and hydrogen were compared. Comparison was made by eleven comparison criterions from different aspects. The most suitable alternative fuel which can be used on ships is determined by defining evaluation scale points for each comparison criterions. Analytic hierarchy process was used to find the weighing of comparison criterions according to given points by five experts to each criterions. Final comparison table is formed including all comparison criterions with given evaluation scale points of each alternative fuels, and weighing for each criterion depend on their importance at maritime sector. Methanol and ethanol, liquefied natural gas, and hydrogen get comparison points of 2.129, 4.092 and 3.796 respectively from the total point of 5.005. Comparison shows that methanol and ethanol do not seem to be preferable to use onboard due to their inadequacy which are investigated in the study. Liquefied natural gas gets the highest total evaluation point in the study, and the most suitable alternative fuel. Hydrogen gets the highest point at safety, bunker capability, durability, adaptability to existing ships, and commercial effects criterions. This study shows that hydrogen can be the alternative to liquefied natural gas used as a fuel at ships, but it requires more studies and improvement on the comply with emission regulations and effect on engine components issues. [ABSTRACT FROM AUTHOR]

Due to the growing concerns of emissions from the shipping industry, the International Maritime Organization (IMO) has set strategies to reduce the CO 2 intensity by 40% in 2030 and cut total GHGs emissions by at least 50% by 2050, with 2008 as a baseline. Clean alternative marine fuels are widely recognized and used as a viable solution for reducing ship-related air pollution. Several studies including traditional reviews have been conducted to examine the literature on cleaner alternative marine fuels and their role in decarbonizing the shipping sector. However, these studies fail to unpack the main research actors, evolutionary nuances, and emerging research hotspots in this field. To quantitatively and qualitatively explore this research field, the current study adopts a bibliometric analysis. 583 eligible documents published from 2000 to 2020 were retrieved and merged from the Web of Science Core Collection and Scopus databases, and analyzed with the R-studio bibliometrix package (Biblioshiny). Results revealed that the field is growing significantly at a growth rate of 15.8%, with key contributions to the field originating from the USA. Liquified Natural Gas has been identified as the most researched alternative shipping fuel. However, recent trends show researchers turning their attention towards methanol, ammonia, and hydrogen fuels. By analyzing the frequently used keywords and relevant articles, it became clear that the research community has focused mainly on the potential of different alternative fuels as a replacement to conventional marine fuels to limit the emissions from the shipping sector from an environmental, technical, and economic perspective. The current study offers a basis for future research into the decarbonization of the shipping industry. [Display omitted] • Bibliometric study on clean marine fuels based on Web of Science and Scopus databases. • A growing research field with an annual growth rate of 15.8%. • Key authors, institutions and countries in the field have been identified. • LNG emerged as the most researched alternative shipping fuel. • Research hotspots and trends on clean marine fuels discussed. [ABSTRACT FROM AUTHOR]