This paper presents a review of the different International Maritime Organization (IMO) initiatives to improve the ship energy efficiency of new and existing ships, which is considered one of the essential tasks to reduce Greenhouse Gas (GHG) in the maritime industry. First, the IMO effort and initiatives and the different indices suggested by the IMO are presented till the last version of the Marine Environment Protection Committee (MEPC), showing the effect of different technologies on reducing the level of indices and the suggested improvement of the terms of indices in the next years. Second, the short- and long-term strategies suggested by the IMO are presented, showing that the effect of indices will be noticed in the short term, while the new fuels will show a significant improvement in the long term. Finally, several examples of cooperation between the different organizations are presented, showing that transferring knowledge and experience will significantly impact the maritime industry and thus lead to the concept of green ships in the near future. This paper shows that the combination of different solutions, the cooperation between stakeholders and the sharing of the data and information are important to achieve the required goal.

The lifecycle greenhouse gas (GHG) emissions (Well-to-Wake) from maritime transport must be reduced by at least 50% in absolute values by 2050 to contribute to the ambitions of the Paris Agreement (2015). A transition from conventional fuels to alternative fuels with zero or lower GHG emissions is viewed as the most promising avenue to reach the GHG reductions. Whereas GHG and toxic pollutants emitted from the use of fossil fuels (heavy fuel oil (HFO) and marine gas/diesel oil (MGO/MDO)) are generally well understood, the emissions associated with the new fuel options are only now being measured and communicated. This review provides an outlook on fuels that could help shipping respond to the decarbonization effort including Liquefied Petroleum Gas (LPG), Liquefied Natural Gas (LNG), methanol, ammonia, and hydrogen. A quantification of the pollutants associated from the use of these fuels is provided and challenges and barriers to their uptake are discussed.

This research presents a review and classification of the published work related to applied risk analysis and risk management in the maritime liquefied natural gas (LNG) sector from 2000 to 2023. The papers are categorised under two primary contexts. The first is the risk analysis theory context which represents the classification with respect to (w. r. t.) the used risk analysis method, the used risk analysis tool, and the objective of risk analysis, whereas the second is the presented case in the risk analysis context which represents the classification w.r.t. the analysed LNG ship type, the analysed operation, and the inclusion level of human error in risk analysis. The above process has revealed that the interest in this domain of research has increased significantly during the past decade. In addition, the use of dynamic risk analysis (DRA) tools, and the inclusion of human error in the risk analysis model have been observed significantly in the past five years, in particular, for modelling the risk of external LNG transfer operations. It is concluded that the inclusion of the effect of human and organisational factors (HOFs) in risk analysis, and the use of DRA methods for modelling the risk of the daily routine operations of the complex maritime LNG systems can improve the management of the operational risk of these systems.

Climate change and global warming are among the most severe threats to the global ecosystem, caused by greenhouse gas emissions. Therefore, all industries that cause environmental emissions should collaborate in the struggle against climate change. In this context, the International Maritime Organization (IMO) approved the initial greenhouse gas strategy at the MEPC 72 session in April 2018 to achieve targets for 2050. With this strategy, the IMO aims to create and improve new regulations that can enhance energy efficiency to achieve their short-term, midterm, and long-term goals. In this study, one of the novel terms, energy efficiency existing ship index (EEXI) values, has been calculated for the Turkish fleet to guide the maritime sector. The Turkish fleet in the study refers to the Turkish-owned vessels both sailing with a national or inter‐ national flag. In accordance with this regulation, the number of Turkish fleets that were identified as either above or below the IMO reference lines has been determined. Additionally, EEXI values have been recalculated using the engine power limitation (EPL) method for ships that ex‐ ceed the required limits, and the success rate of this method has been estimated. As a result, the application of EPL increased the number of ships below the Phase 2 reference line from 15.6 % to 53.1 %. To the best of our knowledge, this research, which has been carried out on all Turkish-owned ships, is the first study intended to serve as a guide for other ship owners in the global maritime industry regarding energy efficiency management.

The fuel consumption of a ship has always been an important research topic, but nowadays its importance has even increased as it is directly related to a ship’s greenhouse gas (GHG) emissions, which is now tightly regulated. In this paper, such a dynamic model is presented. The ship’s resistance in calm water and propeller’s performance in open water are required as input. The hull efficiency is estimated empirically. The diesel engine is modelled by a first-order transfer function with a delayed response and its performance is calibrated with the data from the manufacturer’s catalogue. A governor is applied to maintain the pre-set engine’s rotational speed and to control the engine fuel rate. A slope limiter is employed to approximate the actual engine operation during engine transients. The default values can be obtained from the manufacturer engine load acceptance diagram. The developed model is implemented in MATLAB SIMULINK environment. After validation against third-party published results, the influence of using different types of governors on ship speed and fuel consumption is investigated. The model is also applied to simulate the fuel consumption of a ship during a typical acceleration manoeuvre and the scenario of a real ship encountering harsh weather conditions.

This paper presents a comparative analysis between single and twin-screw propulsion systems of a bulk carrier to evaluate the ship and propeller performance in terms of fuel consumption as well as to discuss the cavitation and noise criteria. An optimization model is developed to select the optimum propeller geometry and operational point along the engine load diagram for the selected engines of each case. The engines are selected from the same series due to the same behaviour along the engine load diagram. The propellers are selected from the B-series as fixed-pitch propellers. It has been concluded that while the components of the single-screw propulsion system are larger than the twin-screw, the single-screw propulsion system shows a reduction in fuel consumption than the twin screw by around 19%, thus affecting the amount of exhaust emissions from the ship. This model helps the ship designers to select a suitable propeller to improve the energy efficiency of the ships.

For the successful operation of any industry or plant continuous availability of power supply is essential. Many of the large-scale plants established their power generation units. Marine power plant having two generators is also fall in this category. In this study, an effort is made to derive and optimize the availability of a marine power plant having two generators, one switch board and distribution switchboards. For this purpose, a mathematical model is proposed using Markov birth death process by considering exponentially distributed failure and repair rates of all the subsystems. The availability expression of marine power plant is derived. Metaheuristic algorithms namely dragonfly algorithm (DA), bat algorithm (BA) and whale optimization (WOA) are employed to optimize the availability of marine power plant. It is revealed that whale optimization algorithm outperforms over dragonfly algorithm (DA), and bat algorithm (BA) in optimum availability prediction and parameter estimation. The numerical values of the availability and estimated parameters are appended as numerical results. The derived results can be utilized in development of maintenance strategies of marine power plants and to carry out design modifications.

The importance of reducing ship resistance is growing considerably as a result of the increase in atmospheric emissions and the drive towards green shipping through decarbonization. Until this point, Energy Saving Devices (ESD), in particular, Hull Vane? (HV), have been widely applied as a potential technique for reducing wave-making resistance for vessels with higher Froude Number (Fr). The advantages of HV for a medium-speed vessel, where the wave-making component accounts for almost 50% of total resistance, have yet to be investigated. This study presents the computational analysis of the KCS model (1∶75.5); for a particular trim condition by using the VOF method and RANS solver. The hull acts as a candidate vessel for the class of medium-speed characteristics. A total of 36 numerical simulations were carried out to study the changes in resistance and motion characteristics of the vessel with and without HV. To validate the numerical setup, the experimental work of Hou et al (2020) on the DTMB hull was used. The effectiveness of HV can be comprehended by the reduction percentage in total resistance, trim, sinkage, and transom wave height, in comparison to bare hull condition. The reduction in total resistance extends up to 6% for Fr = 0.32 with configuration 2 with negative AoF. The CFD results indicate that there is a reduction in trim up to 57% for the maximum speed with a corresponding Fr = 0.34 with a positive angle of foil (AoF). The trim correction effect is increasing with the depth of submergence of HV. Concerning sinkage, there occurs nearly a 31% reduction for Fr = 0.34 with a positive AoF. There exists a substantial reduction in the height of the transom wave with the inclusion of HV, the results of which are discussed in detail. From the presented results, retrofitting the Hull Vane? is effective in the selected speed range but pronouncing as the speed of the vessel increases.

The flutter of a hydrofoil can cause structural damage and failure, which is a dangerous situation that must be avoided. In this work, based on computational fluid dynamics and structural finite element methods, a co-simulation framework for the flow-induced vibration of hydrofoil was established to realize fluid-structure interaction. Numerical simulation research was conducted on the flow-induced vibration characteristics of rigid hydrofoil with 2-DOF under uniform flow, and the heave and pitch vibration responses of hydrofoil were simulated. The purpose is to capture the instability of hydrofoil vibration and evaluate the influence of natural frequency ratio and inertia radius on vibration state to avoid the generation of flutter. The results indicate that when the inflow velocity increases to a certain critical value, the hydrofoil will enter the flutter critical state without amplitude attenuation. The attack angle of a hydrofoil has a significant impact on the vibration amplitude of heave and pitch. Additionally, the natural frequency ratio and inertia radius of the hydrofoil significantly affect the critical velocity of the flutter. Adjusting the natural frequency ratio by reducing the vertical stiffness or increasing the pitch stiffness can move the vibration from a critical state to a convergent state.

In comparison to onshore facilities, ships, and their machinery are subjected to challenging external influences such as rolling, vibration, and continually changing air & cooling water temperatures in the marine environment. However, these factors are typically neglected, or their consequences are deemed to have little effect on machinery, the environment, or human life. In this study, seasonal air & seawater temperature effects on marine diesel engine performance parameters and emissions are investigated by using a full-mission engine room simulator. A tanker ship two-stroke main engine MAN B&W 6S50 MC-C with a power output of 8 600 kW is employed during the simulation process. Furthermore, due to its diverse risks, the Marmara Region is chosen as the application area for real-time average temperature data. Based on the research findings, even minor variations in seasonal temperatures have a significant influence on certain key parameters of a ship’s main engine including scavenge pressure, exhaust temperatures, compression and combustion pressures, fuel consumption, power, and NO_x-SO_x-CO_x emissions. For instance, during the winter season, the cylinder compression pressure (p_c) is recorded at 94 bar, while the maximum pressure (p_c) reaches 110 bar. In the summer, p_c experiences a decrease of 81 bar, while p_z is measured at 101 bar. The emission of nitrogen oxides (NO_x) exhibits a measurement of 784 parts per million (ppm) during winter and 744 in summer. The concentration of sulfur oxides (SO_x) is recorded at 46 ppm in winter and 53 in summer. Given the current state of global warming and climate change, it is an undeniable fact that the impact of these phenomena will inevitably escalate.

Nowadays alternative and innovative energy recovery solutions are adopted on board ships to reduce fuel consumption and harmful emissions. According to this, the present work compares the engine exhaust gas waste heat recovery and hybrid turbocharger technologies, which are used to improve the efficiency of a dual-fuel four-stroke (DF) marine engine. Both solutions aim to satisfy partly or entirely the ship’s electrical and/ or thermal loads. For the engine exhaust gas waste heat recovery, two steam plant schemes are considered: the single steam pressure and the variable layout (single or dual steam pressure plant). In both cases, a heat recovery steam generator is used for the electric power energy generation through a steam turbine. The hybrid turbocharger is used to provide a part of the ship’s electric loads as well. The thermodynamic mathematical models of DF engines, integrated with the energy recovery systems, are developed in a Matlab-Simulink environment, allowing the comparison in terms of performance at different engine loads and fuels, which are Natural Gas (NG) and High Fuel Oil (HFO). The use of NG always involves better efficiency of the system for all the engine working conditions. It results that the highest efficiency value achievable is 56% at 50% maximum continuous rating (MCR) engine load.

In this study, environmental and economic examinations of Liquefied Natural Gas (LNG) investments are conducted. A year-long noon report data is received from a container ship and LNG conversion is performed. Savings from both the fuel expenses and the amount of the emissions are calculated and presented. To eliminate the fuel consumption uncertainties in future operation periods of the stated ship, different scenarios that simulate various fuel consumption statuses are created and analyzed within the Monte Carlo Simulation method. Lastly, calculations are made with two different time prices, approx. one and half year apart. As a result of the analyses, LNG can provide high environmental benefits since it reduces 99% for SOx, 95% for PM₁₀, 95% for PM_2.5, 41% for CO₂, and 82% for NOx, respectively. It is also determined that LNG investment is highly sensitive to fuel prices. In addition, the LNG usage can be beneficial for maritime companies in terms of marine policies such as paying carbon tax based on the expanding European Union Emission Trade System to maritime business. Still, it needs supportive carbon reduction method to comply with the maritime decarbonization strategy. This study has great importance in that the economic analysis way presented is able to adapt any alternative fuel system conversion for the maritime industry.

A combined system including a solid oxide fuel cell (SOFC) and an internal combustion engine (ICE) is proposed in this paper. First, a 0-D model of SOFC and a 1-D model of ICE are built as agent models. Second, parameter analysis of the system is conducted based on SOFC and ICE models. Results show that the number of cells, current density, and fuel utilization can influence SOFC and ICE. Moreover, a deep neural network is applied as a data-driven model to conduct optimized calculations efficiently, as achieved by the particle swarm optimization algorithm in this paper. The results demonstrate that the optimal system efficiency of 51.8% can be achieved from a 22.4%/77.6% SOFC-ICE power split at 6 000 kW power output. Furthermore, promising improvements in efficiency of 5.1% are achieved compared to the original engine. Finally, a simple economic analysis model, which shows that the payback period of the optimal system is 8.41 years, is proposed in this paper.

In this paper, the spray and combustion characteristics of diesel/butanol-blended fuels were studied within a high-temperature and high-pressure constant volume chamber equipped with a single-hole injector. Two blends with 80% diesel/20% butanol and 60% diesel/40% butanol mixed by volume were tested in this study. The pure diesel B0 was also tested here as a reference. The spray penetration, flame lift-off length, and soot optical thickness were obtained through high-speed schlieren imaging, OH^* chemiluminescence, and diffused back-illumination extinction imaging technique, respectively. The thermogravimetric curves of different fuels were obtained through a thermogravimetric analyzer. The results showed that butanol/diesel blends presented a longer ignition delay (ID) and flame lift-off length compared with pure diesel, and such finding was mainly caused by the lower cetane number and higher latent heat of vaporization of n-butanol. With the increase in the n-butanol ratio, soot production in the combustion process decreased significantly. Given the shorter ID period, the soot distribution of pure diesel reached a steady state earlier than the blends.

To study the applicability of biodiesel in marine engines, this research investigated the performance, combustion characteristics, and emission characteristics of biodiesel (B100), diesel, and a 50% volume blend of the two fuels (B50) in a marine engine. This study was conducted on a 4-cylinder, 520 mm-bore, two-stroke, low-speed marine engine with a common rail fuel and exhaust gas charge system. The three fuels were tested at different loads from 25%–100% with a step size of 25%. Results showed that the fuel consumption of pure biodiesel increased by about 13.5% and 3.8% relative to that of diesel at 25% and 100% loads, respectively, and by about 6% at 50% and 75% loads. In-cylinder combustion pressure was slightly reduced when the engine ran on biofuel, and black carbon emissions from biodiesel were reduced by an average of 54.7%. Compared with those from diesel, the carbon CO and total hydrocarbon emissions from B100 were reduced by 11.3% and 39%, respectively. Nitroxide emissions were elevated for B100 and B50 under all loading conditions. The properties of B50 blended diesel lie between those of B100 and diesel. In terms of combustion characteristics and emissions, biodiesel can be used without changing the engine parameters and can effectively reduce pollution, such as black carbon and carbon monoxide.

This article explores the possibilities of inedible biodiesel as a viable and environmentally friendly substitute fuel for marine diesel engines in India. This article encompasses on various crucial elements, including engine compatibility, biodiesel blends, fuel quality, emissions reduction, regulatory compliance, cost analysis, environmental advantages, and research and development. Implementing biodiesel in maritime operations within India presents favourable opportunities for mitigating carbon emissions, improving air quality, bolstering energy security, promoting sustainable agriculture, and harmonizing with international environmental objectives. Nevertheless, the effective incorporation of biodiesel necessitates a meticulous examination of multiple variables and an all-encompassing methodology that involves formulating policies, investment in infrastructure, research and development, and collaboration among relevant parties. Adopting biodiesel in India’s maritime sector offers a promising prospect for substantially contributing to sustainability and environmental stewardship.