Modern marine propulsion systems must be reliable, energy efficient, environmentally friendly, and economical. Efforts to reduce fuel costs and carbon dioxide (CO₂) emissions per nautical mile have a significant impact on the choice of propulsion system. Considering that there is no alternative for maritime transport, various technical and technological solutions are being considered that aim to improve efficiency and reduce the negative impact on the environment. One of the ways to achieve this goal is slow steaming, which reduces fuel consumption and CO₂ emissions. The designed speed of the vessel has a significant impact on the efficiency of slow steaming. Slow steaming is particularly suitable for large container ships with a design speed of more than 20 knots. In this paper, the effects of slow steaming are analyzed using the example of a container ship with diesel-engine propulsion. Propulsion systems with low-speed and medium-speed marine diesel engines with mechanical power transmission are investigated. Data on the required engine power and propeller speed were used for the study, obtained from calculations during testing of the ship’s hull model. The effects of speed reduction on specific fuel consumption and emission reduction were analyzed using numerical models of two-stroke and four-stroke diesel engines. The models were calibrated and validated using data provided by the engine manufacturers. The paper analyses four different cases where one or two low-speed diesel engines, or three or four medium-speed diesel engines, are used for propulsion. The analysis concludes that slow steaming can effectively reduce fuel consumption and CO₂ emissions, but the choice of the optimal propulsion system is highly dependent on maritime market conditions in maritime transportation. The choice of propulsion system affects the potential of slow steaming.

This paper presents the application of machine learning (ML) methods in setting up a model with the aim of predicting the energy efficiency of seagoing ships in the case of a vessel for the transport of liquefied petroleum gas (LPG). The ML algorithm is learned from shipboard automation system measurement data, noon logbook reports, and related meteorological and oceanographic data. The model is tested with generalized linear model (GLM) regression, multilayer preceptor (MLP), support vector machine (SVM), and random forest (RF). Upon verification of modeling framework and analyzing the results to improve the prediction accuracy, the best numeric prediction algorithm is selected based on standard evaluation metrics for regression, i.e., primarily root mean square error (RMSE) and relative absolute error (RAE). Experimental results show that, by taking an adequate combination and processing of relevant measurement data, RF exhibits the lowest RMSE of 17.2632 and RAE 2.304%. Furthermore, this paper elaborates the selection of measurement data, the analysis of input parameters, and their significance in building the prediction model and selection of suitable output variables by the ship’s energy efficiency management plan (SEEMP). In addition, discretization was introduced to allow the end user to interpret the prediction results, placing them in the context of the actual ship operations. The results presented in this research can assist in setting up a decision support system whenever energy consumption savings in a marine transport are at stake.

This paper estimates the exhaust gases emissions from ships in the international marine traffic in the port of Zadar. The emission results refer to the pollutants such as nitrogen oxides (NOx), sulphur oxides (SOx), particulate matter (PM), volatile organic compounds (VOC) and greenhouse gases such as carbon dioxide (CO2). The methodology that has been applied, so called “bottom-up” approach, uses detailed data on ship’s characteristics (engine power, the load factor, fuel type, the emission factor) and time spent cruising and hotelling. The estimated inventory for the port of Zadar includes overall marine traffic from the passenger and cargo terminals. The exhaust gases emissions have been divided into three ship’s activities: cruising in the reduce speed zone, hotelling (at berth) and manoeuvring. The results (tons/year) have shown that approximately 80% of total emissions come from passenger ships and 20% from cargo ships.

Over the past decade regulatory emission control has been adopted and even stricter emission reductions are being considered. In order to comply with the present and future regulations the ship owners and engine manufacturers are facing a difficult task. The shipping industry is presently offering multiple choices such as scrubbers and Selective Catalytic Reduction (SCR), dual fuel engines, Liquefied Natural Gas / Liquefied Petroleum Gas (LNG/LPG) powered engines, and lately the introduction of methanol and ethanol as alternative fuels. This work presents a short overview of the possible use of methanol and ethanol as lternative fuels in shipping. The first part of this work deals with physical properties of methanol and ethanol, production and availability, as well as advantages and disadvantages in comparison with other fuels. In the second part the cost perspective is presented together with the cost-benefit analysis, which is the most important aspect in the ship owner’s decision whether to invest into the new alternative. Methanol and ethanol are not magical solutions, but rather another alternative which, from the cost perspective, offers a potential under certain circumstances. These circumstances are competitive prices in comparison to Marine Gas Oil (MGO) and time spent in Emission Control Area (ECA) which should be a large portion of the total sailing time. In this paper the scientific methodology was followed by using the method of compilation, the descriptive and the comparative methods.

Having come into effect, the International Convention for the Control and Management of Ships’ Ballast Water and Sediments of 2004 requires ships to process their ballast water in accordance with specific standards. Different processing methods require different use of ship power, thus affecting fuel oil consumption, ships’ energy efficiency, and the ship economics in general. This paper presents the analysis and comparison of the economic viability of systems using two dominant ballast water treatment methods on merchant ships. The cost effectiveness of these methods, UV irradiation and electrochlorination, is compared to the standard efficiency of ballast water exchange using sequential flow method as a reference. The process efficiency is measured through fuel oil consumption on board. Taking into account possible variations in efficiency due to different designs and environmental constraints and assumptions, the findings are in favor of the electrochlorination method.

The medium-speed diesel engine in diesel-electric propulsion systems is increasingly used as the propulsion engine for liquefied natural gas (LNG) ships and passenger ships. The main advantage of such systems is high reliability, better maneuverability, greater ability to optimize and significant decreasing of the engine room volume. Marine propulsion systems are required to be as energy efficient as possible and to meet environmental protection standards. This paper analyzes the impact of split injection on fuel consumption and NO_x emissions of marine medium-speed diesel engines. For the needs of the research, a zero-dimensional, two-zone numerical model of a diesel engine was developed. Model based on the extended Zeldovich mechanism was applied to predict NO_x emissions. The validation of the numerical model was performed by comparing operating parameters of the basic engine with data from engine manufacturers and data from sea trials of a ship with diesel-electric propulsion. The applicability of the numerical model was confirmed by comparing the obtained values for pressure, temperature and fuel consumption. The operation of the engine that drives synchronous generator was simulated under stationary conditions for three operating points and nine injection schemes. The values obtained for fuel consumption and NO_x emissions for different fuel injection schemes indicate the possibility of a significant reduction in NO_x emissions but with a reduction in efficiency. The results showed that split injection with a smaller amount of pilot fuel injected and a smaller angle between the two injection allow a moderate reduction in NO_x emissions without a significant reduction in efficiency. The application of split injection schemes that allow significant reductions in NO_x emissions lead to a reduction in engine efficiency.