Ship Applications Research Articles

Optimization of marine hybrid power energy consumption

Abstract The energy and power system of the ship is the core of the ship, and the composite energy storage plays a great role in reducing the load power fluctuation of the ship, which effectively optimizes the energy efficiency index and reliability of the ship. [Objective] To better optimize the ship energy management system, a control model is established according to the characteristics of the energy system of hybrid electric ships. [Method] Energy consumption optimization is carried out by using a rule-based energy control strategy and energy control strategy based on equivalent fuel consumption minimum (ECMS). The dynamic control and strategy of the hybrid ship were optimized, and the data simulation and real ship application were carried out on the hybrid experiment platform. [Results] According to the data and results of the real ship application, the following results were shown: The daily fuel saving rate of the ECMS strategy is 14.6% in normal operating conditions and 13.3% in cruise operating conditions. [Conclusion] It has a great effect on the improvement of ship energy efficiency.

Analysis of the Impact of Dynamic Operation of PEMFCs for Ship Applications

<i>Dynamic responses of polymer electrolyte membrane fuel cells (PEMFC) were analyzed under varying loads to understand the performance of PEMFCs for ship applications. Experiments employing single cells were conducted under a static load with a constant current of 6.64 A and dynamic loads at a ramp rate of 2.5%/s and 5.0%/s, representing a simplified ship operation condition. Under the static load, the voltage drop was 0.054 V at 1.00 A/cm<sup>2</sup> and was dominant below 0.40 A/cm<sup>2</sup>. In contrast, under the dynamic load (5.0%/s ramp rate), the voltage drop was 0.061 V at 1.00 A/cm<sup>2</sup> and was dominant above 0.40 A/cm<sup>2</sup>, with similar behavior observed at the ramp rate of 2.5%/s. To compare performance across load conditions, degradation rates were calculated through linear regression of the voltage drop for each current density. The degradation rate at 1.00 A/cm<sup>2</sup> was 0.143 mV/h under static load conditions and 0.174 mV/h under dynamic load conditions (ramp rate: 5.0%/s), indicating approximately 21% greater degradation rates than those observed under static load conditions. These experimental results provide foundational data for PEMFC performance analysis, particularly regarding performance degradation caused by dynamic loads in marine environments.</i>

Energy Use and Carbon Footprint Assessment in Retrofitting a Novel Energy Saving Device to a Ship

The Gate rudder system (GRS) was recently introduced as an innovative energy-saving device (ESD) for ships, and it is the most attractive ESD currently used in the market, with double figures of fuel savings in full-scale (>10–35%) compared with a ship with a conventional rudder system (CRS). Although there are few new ship applications of GRS, the recently completed EC-H2020 GATERS project successfully demonstrated its unique energy-saving and manoeuvrability benefits as a “retrofit” solution for an existing general cargo vessel for the first time. The project results suggested that the GRS holds significant potential for retrofitting existing ships to enhance fuel efficiency (~35%) and improve manoeuvrability. Nevertheless, the application was a comprehensive undertaking requiring various work tasks such as component manufacturing, removing existing systems, and modification and upgrading works, with substantial energy consumption and environmental impacts. Therefore, it was insightful to study energy use and environmental impacts in a GRS retrofit process. This study developed and implemented a comprehensive energy consumption and carbon footprint assessment framework for the GRS retrofit in the GATERS project. A detailed assessment of energy consumption and related carbon emissions was performed during the major stages of manufacturing, system removals, and modifications and assembly in the GRS retrofit. Also, the potential savings in energy use and emissions were addressed. The results demonstrated that the manufacturing stage was the most energy-intensive phase, being responsible for 91.4% of total electricity and 46.7% of fuel-based thermal energy use. The system removals accounted for 53.3% of the fuel-based thermal energy, whereas the modification and assembly work accounted for about 7.7% of the total electricity use. Additionally, various measures such as clean electrification, energy efficiency, mould/tool reuse, and component reuse to reduce the energy consumption and related carbon emissions in future GRS retrofit applications were addressed and discussed together with their reduction potentials.

MAEE-Net: SAR ship target detection network based on multi-input attention and edge feature enhancement

Synthetic Aperture Radar (SAR) imagery has a wide range of applications in search and rescue ships lost contact and military reconnaissance. When detecting multi-scale targets, better determination of the target edge is conducive to improving the detection accuracy of the model, but most of the existing methods lack research on this aspect. To fix the problems mentioned earlier, this paper suggests using a SAR Ship target detection network called MAEE-Net. In this paper, a multi-input attention-based feature fusion module (MAFM) and an edge feature enhancement module (EFEM) are proposed. MAFM uses attention mechanism with multi-input and multiple-output to improve attention to shallow feature map target and suppress invalid information, so as to improve the information utilization rate of each layer. To make the network better at detecting the edges of ships, EFEM uses double-branched structure to carry out fine-grained information retention and edge feature extraction. PIoU v2 is introduced to enhance multi-target processing capability. Experiments were carried out on SSDD dataset and SAR-Ship-Dataset, the overall detection accuracy was as high as 98.6% and 94.7%. The detection accuracy was 93.5% and 99.3% on inshore and offshore sub-datasets of SSDD dataset. Experimental results on two datasets show that our model is impactful.

Assessment of the effectiveness of ship machinery noise reduction measures using a test platform in a water basin

Underwater radiated noise (URN) from commercial shipping is partly responsible for increased ocean ambient noise levels in the last decades. To preserve marine wildlife, there is a need to reduce it. Machinery noise is the dominant URN source at lower speeds. Mitigation technologies exist to reduce it, but a lack of quantitative data regarding their effectiveness results in limited practical ship applications since the cost-to-benefit ratio is imprecise. A small ship-like structure (test platform) representative of a ship section is designed and constructed to conduct measurements in a controlled environment and at a lower cost than actual on-ship testing. The platform is deployed in a water basin whose acoustic response is first characterized by reverberation measurements. Vibroacoustic sources simulate structure-borne and airborne noise, while hydrophones and sensors measure the response in the water basin and of the platform. Measurements with and without standard mitigation technologies installed in the platform are conducted to quantify the insertion loss. Up to 37 and 20 dB URN reductions are obtained with elastic mounts and mineral wool, respectively. The results obtained with the platform and the developed methodology can support and guide the implementation of mitigation measures in current and future ship constructions.

Clean energy ship application to promote carbon neutrality in global maritime industry: State governance or international supervision？

The global maritime industry is facing the goal to achieve "carbon neutrality", and substituting traditional ship fuel with clean energy is the most important solution. Whether to promote clean-energy ships through state governance or unified international supervision to achieve carbon neutrality has been a long-standing debate. This study employs both a tripartite evolutionary game model and a quadrilateral evolutionary game model to compare the effectiveness of state governance and unified international supervision in promoting clean-energy ships. The tripartite model simulates interactions between local governments, shipping companies, and shippers, revealing that high subsidy costs reduce local governments' incentives to promote clean-energy ships. The quadrilateral model introduces international supervision, demonstrating that a unified international oversight mechanism can accelerate the global maritime industry's progress toward carbon neutrality. Numerical simulations indicate that lowering the purchase costs of clean-energy ships and introducing government subsidies significantly influence the adoption of clean-energy ships, while supervision costs impact the effectiveness of international regulations. These findings provide critical insights for policymakers aiming to balance financial incentives and global supervision strategies to foster low-carbon development in the maritime sector.

Experiment-based feasibility study of LNG equipment-embedded fuel gas supply system for vessels

This study introduces and validates an innovative Liquefied Natural Gas (LNG) Equipment-Embedded Fuel Gas Supply System (LEEF) designed for small LNG-fueled vessels. These ships face significant challenges in implementing LNG Fuel Gas Supply Systems (FGSS) owing to limited space and stringent regulatory requirements to reduce Greenhouse Gas (GHG) emissions. The LEEF system addresses these challenges by replacing the external Pressure Build-up Unit (PBU) with an integrated in-tank Electric PBU (EPBU) and vaporizer, enhancing spatial efficiency and safety while reducing LNG leakage risks. The experimental results indicate that the Pressure Rise Rate (PRR) accelerates with higher tank levels and increases the EPBU power. The PRR doubled at higher liquid levels and improved by 30–44 % with increased EPBU power at a constant liquid level. The EPBU effectively maintained the tank pressure against flow variations, achieving pressure control with minimal power. A review of international regulations and codes confirms that the EPBU satisfies explosion-proof standards and ensures stable operation. The LEEF system demonstrated substantial potential for application in small LNG-fueled ships by combining improved spatial efficiency and enhanced safety. This study contributes to the development of the FGSS solution that is more compact and safer compared to conventional systems, encouraging sustainable marine propulsion.

The Application and Prospects of Electric Ships in the Maritime Industry

The Application and Prospects of Electric Ships in the Maritime Industry

The challenge of safe and sustainable development of the unmanned ship: seeking for effective legal responses

Technological innovation is changing the way maritime transport is done, and automated driving is one of the hot topics, including unmanned ships that use automated driving technology, but legal challenges to the application of unmanned ships in the shipping industry must be resolved before that happens—whether and how the principles of existing international conventions regarding unmanned ships. To deal with this problem, it is far from enough to rely on the efforts of international organizations or the revision of international conventions. The paper analyzes several typical legal issues faced by unmanned ships: the legal definition of unmanned ships, the seaworthiness of unmanned ships, the master and crew rules, and the collision and rescue of unmanned ships, taking China as an example, the paper explains reasonable and effective legal path of domestic and international laws, trying to seek solutions at the level of domestic law beyond international convention. The paper concludes that the traditional navigation rules have largely been developed to meet the needs of manned transportation, and cannot be fully applied to unmanned ships. Therefore, until there is an international regulation specifically for unmanned ships, it would be appropriate to interpret or revise existing international conventions to apply to unmanned ships. And for countries including China, it is important to consider the improvement of domestic laws.

Study on Shipboard Carbon Capture Technology with the MEA-AMP-Mixed Absorbent Based on Ship Applicability Perspective.

Ocean-going ships powered by diesel engines were the main source of CO2 emissions in the marine environment, and it was imperative to study shipboard carbon capture technology. Based on this, the whole process of CO2 absorption and desorption was studied with a mixed amine (MEA + AMP). The effective cycle time, CO2 absorption capacity, desorption efficiency, energy consumption, foaming and volatilization characteristics, and other key parameters were compared and analyzed under the conditions of required capture efficiency by ships. The MEA20% + AMP10% solution showed good CO2 absorption performance. At 80% capture efficiency, the desorption efficiency was more than 50%. The absorption capacity was close to that of the MEA30% solution, and the cycle time was basically the same. The effective cycle time under the reaction time of 2 s was also determined, which was an important parameter for setting the desorption frequency and had a great effect on reducing the desorption energy consumption. This work can provide an important reference value for the real ship application of carbon capture devices.

Thermal conductivity evaluation of radiative entropy optimized cross-flow in Eyring Powell nanofluid past a permeable deformable sheet: the case of solar-powered ship application

Thermal conductivity evaluation of radiative entropy optimized cross-flow in Eyring Powell nanofluid past a permeable deformable sheet: the case of solar-powered ship application

Thermodynamic performance analysis of direct methanol solid oxide fuel cell hybrid power system for ship application

Methanol is a fuel that can be directly supplied to solid oxide fuel cell (SOFC) without carbon deposition. This paper introduces the direct methanol SOFC-Internal combustion engine (ICE) hybrid power and SOFC-Gas turbine (GT) hybrid power systems. Thermodynamic performance analysis of the hybrid power systems and an investigation into the impact of various parameters were conducted. The results indicate that the electric efficiency of the SOFC-ICE system is 56.07 %, which is 3 percentage points higher than the SOFC-GT system but 3–4 percentage points lower than the SOFC-ICE system with pre-reforming. Increasing fuel utilization rate, operation temperature, and excess air ratio is beneficial to the performance of the SOFC, and raising current density helps improve the system's power density. Load-sharing strategy research demonstrates that in a scenario where the power ratio between SOFC and the ICE is 35:65, compared to a methanol engine, the efficiency of the SOFC-ICE hybrid power system increases by 4.3 %. Despite a 1.4-fold increase in weight and a 1.66-fold increase in cost, the fuel consumption rate and carbon emissions decrease by 8.8 %. Therefore, the strategy of combining a high-power engine with a low-power SOFC is currently a suitable load-sharing strategy for ship applications.

Developed Status and Forecast of Intelligent Ship Application

The concept of smart ships is not limited to ship autonomous driving, it covers a broader scope, including the full life cycle of ship design, construction, operation and maintenance. By integrating advanced sensors, navigation systems and data analysis platforms, smart ships are able to monitor ship status and the Marine environment in real time, optimize route planning and improve fuel efficiency, thereby reducing energy consumption and greenhouse gas emissions. In addition, smart ships can revolutionize the shipping industry by improving maritime safety and reducing human error through remote control and autonomous decision-making. In recent years, smart ship technology has gradually moved from the theoretical research stage to practical application, and has attracted wide attention from the global shipping industry. A number of international cooperation and research projects have been launched to explore the practical application potential and promotion paths of smart ships. However, the development of smart ships also faces many challenges, including technical difficulties, legal and regulatory restrictions, and public acceptance issues. This paper will deeply discuss the current development status of smart ships, analyze the main challenges it faces, and forecast the future development trend, in order to provide reference and inspiration for the innovative development of the shipping industry.

Hazard comparison of thermal runaway of electric marine battery cabinet under different trigger modes

Currently, the transportation industry, especially shipping, is still accompanied by serious carbon emissions and pollution. Electric ships are the most promising way to solve this problem. However, the application of electric ships in maritime affairs also faces many technical difficulties. This paper studies the heat generation and heat transfer in electric Marine battery cabinets (EMBC). Based on the Multi-Scale and Multi-Domain (MSMD) solution method, this study uses the Newman, Tiedemann, Gu, and Kim (NTGK) battery model to solve the thermal runaway propagation (TRP) of the EMBC, and then makes a visual analysis of the TRP of the EMBC with the three-layer Battery module (BM) structure. Furthermore, the TRP of the three-layer BM is compared based on three different triggering modes. Through analysis and comparison, it is found that among the three TR triggering modes: single battery heating, heat source at the bottom of the module, and heat source at the top. The first mode corresponds to a maximum heat release (HR) of 214.7 GJ, while the third mode exhibits a minimum HR of 212.3 GJ. Furthermore, the maximum temperature reached by the battery under the third mode is 1568 K, which is lower than that achieved in the other two modes. Additionally, it should be noted that the second mode has a higher maximum HR rate of 5772 GW/m3 compared to the third mode. The TR hazard resulting from heating at the bottom of the battery module outweighs that caused by heating at the top, without taking into account human-induced heating factors. The propagation of TR triggered by a single heat source throughout the EMBC can be inhibited within 226 s in the same layer, and prevented from spreading to the remaining layers for up to 596 s. In the present study, a new insight is presented to reveal the TR characteristics of the EMBC under different triggering modes, and quantify the TR duration.

DNV issues GASA to HD Hyundai for ‘world-first’ hybrid super-strength support structure

DNV has presented HD Hyundai with a general approval for ship application (GASA) for a new high-strength composite hybrid support system for independent tanks on liquefied gas carriers.

A Fault-Tolerant Control Method Based on Reconfiguration SPWM Signal for Cascaded Multilevel IGBT-Based Propulsion in Electric Ships

Electric ships have been developed in recent years to reduce greenhouse gas emissions. In this system, inverters are the key equipment for the permanent-magnet synchronous motor (PMSM) drive system. The cascaded insulated-gated bipolar transistor (IGBT)-based H-bridge inverter is one of the most attractive multilevel topologies for modern electric ship applications. Usually, the fault-tolerant control strategy is designed to keep the ship in operation for a certain period. However, the fault-tolerant control strategy with hardware redundancy is expensive and slow in response. In addition, after fault-tolerant control, the ship’s PMSM may experience shock and overheating, and IGBT life is reduced due to uneven switching frequency distribution. Therefore, a stratified reconfiguration carrier disposition Sinusoidal Pulse Width Modulation (SPWM) fault-tolerant control strategy is proposed. The proposed strategy can achieve fault tolerance without any extra hardware. A reconfiguration carrier is applied to improve the fundamental amplitude of inverter output voltage to maintain the operation of the ship’s PMSM. In addition, the available states of faulty H-bridge are fully used to contribute to the output. These can improve the life of IGBTs by reducing and balancing the power loss of each H-bridge. The principles of the proposed strategy are described in detail in this study. Taking a cascaded H-bridge seven-level inverter as an example, simulation and experimental results verify that the proposed strategy, in general, has a potential future application on electric ships.

Evaluation of the performance of technologies for reducing ships' machinery noise using a small-scale ship-like structure in a Water Basin

Ocean ambient levels have increased in the last decades, especially in the low-frequency domain (under 500 Hz). This increase is partly due to underwater radiated noise (URN) from commercial ships. Excessive URN harms marine life and is, therefore, considered a pollution that needs to be reduced. At low speeds, machinery is the primary noise source on ships. Mitigation technologies exist to limit machinery’s contribution to URN. While implementing these technologies is costly, a lack of quantitative data regarding their exact performances usually results in limited concrete ship applications since the cost-to-benefit ratio is imprecise. This study aims to quantify better the performance of standard noise mitigation technologies using a small-scale ship-like structure in a water basin. The basin’s acoustic field is first characterized with and without the structure. The structure is then equipped with different mitigation technologies. A loudspeaker and a vibration shaker are fed with pink noise or measured signals on actual machinery. Hydrophones, microphones, accelerometers, and force sensors measure the response in the basin and on the structure. The performance of each tested technology is evaluated and ranked in terms of URN reduction. The relative contributions of airborne and structure-borne transmission paths on URN are also examined.

A novel multi-degree of freedom kinetic energy harvester for self-powered low-power applications in ships

The utilization of kinetic energy from the motion of small fishing boats to energize ship-borne wireless sensors offers a promising solution to address the power supply challenges of these sensors in the maritime environment. Nonetheless, the constrained scope of retrievable kinetic energy in the prevailing ship-borne kinetic energy harvester has evolved into a hindrance, curbing its progression. Hence, this paper proposed a novel multi-degree of freedom kinetic energy harvester for low-power applications in ships, where the harvester is harnessed by combining a ball rod, sliding bearing, and slider body. Relying on this mechanical device, the ship's kinetic energy in the surge, roll, sway, and pitch directions is transformed into the swinging motion of the mass ball, subsequently converted into the movement of the slider body. Under the influence of the magnetic force between the slider body and the piezoelectric beam, the piezoelectric beam experiences frequent oscillations, ultimately translating mechanical motion into electrical energy. The experimental results show that the harvester can charge capacitors with capacities of 220 μF, 470 μF, and 1000 μF to 1 V within time intervals of 15 s, 24 s, and 36 s. The prototype has been effectively deployed on a ship in an artificial lake, achieving an impressive maximum average power output of 173.10 μW. This study serves as compelling evidence that the harvesting of kinetic energy from ships presents a promising solution for self-powering low-energy applications onboard while also introducing a novel design concept for applying kinetic energy harvesters on fishing vessels.

Numerical Study on Compact Design in Marine Urea-SCR Systems for Small Ship Applications

With increasingly stringent emissions legislation, such as that stipulated by the International Maritime Organization, for nitrogen oxide emission reduction in marine diesel engines, the imperative of curtailing nitrogen oxide emissions from marine diesel engines is intensifying. Consequently, the significance of aftertreatment technologies, including diesel particulate filters (DPFs) and selective catalytic reduction (SCR), is poised to grow substantially. In particular, a redesign is required to reduce the size of DPF and SCR systems for application in small ships. In this study, we varied the shape of the filters in DPF and SCR systems, aiming to achieve a distinct flow pattern and enable overall miniaturization. The performance metrics, including the nitric oxide (NO) reduction rate, NH3 slip rate, and pressure drop, of the redesigned models were compared with those of the conventional model. Computational fluid dynamics simulations were used to compare the performance of the redesigned model with that of the conventional model in terms of NO reduction and pressure drop. The redesigned system achieved a NO reduction rate of 6.9% below that of the conventional system, offering additional noteworthy benefits such as a 50% reduction in both pressure and overall length.

Exergetic and exergoeconomic evaluation of an SOFC-Engine-ORC hybrid power generation system with methanol for ship application

The SOFC-Engine hybrid system is considered suitable as a marine power system due to its impressive attributes, including high efficiency and effective adaptability to variable loads. Combined with the ORC system and methanol fuel, the system's efficiency and carbon reduction can be taken to the next level. This study introduces a novel solid oxide fuel cell (SOFC)-Engine-Organic Rankine cycle (ORC) hybrid power generation system that operates on methanol. Rigorous assessments were conducted utilizing energy analysis, exergetic analysis, and exergoeconomic analysis. These evaluations aimed to pinpoint precise strategies for enhancing system efficiency while curbing expenses. The results show that the power generation efficiency of the hybrid system is 61.86%, and the exergy efficiency was 58.06%. Notably, the air preheater and engine emerge as components causing substantial exergy losses. Through exergoeconomic analysis, the exergy cost distribution across all system parts was unveiled. The reformer's exergoeconomic factor registers the highest at 77.62%. Consequently, mitigating the exergy cost associated with the reformer holds paramount importance in augmenting overall system revenue. Remarkably, the engine incurs the highest cost of exergy destruction at 10.134 $/h. Overall, this research offers pivotal insights for optimizing component performance and driving cost reductions.