Search Results (44)

This paper presents a robust optimization-based approach for voyage and power generation scheduling to enhance the economic efficiency and reliability of electric propulsion ships powered by polymer electrolyte membrane fuel cells (PEMFCs) and battery energy storage systems (BESSs). The scheduling method is formulated considering generation cost curves of PEMFCs with mixed-integer linear programming (MILP) and is extended to a robust optimization framework that accounts for marine environmental uncertainties. The robust optimization approach, implemented via the column-and-constraint generation (C&CG) method, ensures stable operation under various uncertainty scenarios, such as wave speed and direction influenced by wind and tidal currents. To validate the proposed method, a simulation was conducted under realistic operational conditions, followed by a case study comparing the MILP and robust optimization approaches in terms of economic efficiency and reliability. Additionally, the optimization model incorporated degradation costs associated with PEMFCs and BESSs to account for long-term operational efficiency. The case study assessed the performance of both methods under load variation scenarios across different marine environmental uncertainties. Full article

Owing to the global concern regarding fossil energy consumption and carbon emissions, the power supply for traditional diesel-driven ships is being replaced by low-carbon power sources, which include hydrogen energy generation and photovoltaic (PV) power generation. However, the uncertainty of shipboard PV power generation due to weather changes and ship motion variations has become an essential factor restricting the energy management of all-electric ships. In this paper, a deep reinforcement learning-based optimization algorithm is proposed for a green ship energy management system (EMS) coupled with hydrogen fuel cells (HFCs), lithium batteries, PV generation, an electric power propulsion system, and service loads. The focus of this study is reducing the total operation cost and improving energy efficiency by jointly optimizing power generation and voyage scheduling, considering shipboard PV uncertainty. To verify the effectiveness of the proposed method, real-world data for a hybrid hydrogen- and PV-driven ship are selected for conducting case studies under various sailing conditions. The numerical results demonstrate that, compared to those obtained with the Double DQN algorithm, the PPO algorithm, and the DDPG algorithm without considering the PV system, the proposed DDPG algorithm reduces the total economic cost by 1.36%, 0.96%, and 4.42%, while effectively allocating power between the hydrogen fuel cell and the lithium battery and considering the uncertainty of on-board PV generation. The proposed approach can reduce energy waste and enhance economic benefits, sustainability, and green energy utilization while satisfying the energy demand for all-electric ships. Full article

Ammonia has attracted much interest as a potential green and renewable hydrogen carrier or energy vector. Compared to hydrogen, ammonia offers several advantages. For example, ammonia has a significantly higher energy density and can be liquefied at room temperature at a moderate pressure of 8 bars. While ammonia can be cracked to supply hydrogen, it is also possible to convert it directly into high-temperature solid oxide fuel cells (SOFCs) to generate electricity. The Ship-FC project aims to install an ammonia-fed 2MW SOFC system on board the vessel Viking energy to demonstrate the feasibility of zero CO₂ emission shipping. For this NH₃ SOFC system, a catalytic afterburner is required to remove the hydrogen and ammonia present in the SOFC off-gas and to recover heat. The current study analysed the effects of different catalyst supports, with a focus on NO_X formation through the combustion of an SOFC off-gas surrogate. The study investigated the performance of catalysts based on the active metals, platinum and iridium, as well as the catalyst supports, Al₂O₃, SiO₂, and TiO₂. The results were correlated with catalyst characterisation data and ammonia TPD results. The investigations showed that the formation of NO_X was clearly affected by the nature of the catalyst support. The highest selectivity towards NO_X was observed for Al₂O₃, followed by SiO₂, and the lowest selectivity was observed for TiO₂. This trend was evident for the supported platinum and iridium catalysts and for the samples exclusively containing the support. The trend for N₂O formation was opposite to that of NO_X formation (TiO₂ > SiO₂ > Al₂O₃) in both the presence and absence of platinum or iridium. Full article

This research aims to assess the integration of different fuel cell (FC) options with battery and waste heat recovery systems through a mathematical modelling process to determine the most feasible retrofit solutions for a marine electricity generation plant. This paper distinguishes itself from existing literature by incorporating future cost projection scenarios involving variables such as carbon tax, fuel, and equipment prices. It assesses the environmental impact by including upstream emissions integrated with the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator (CII) calculations. Real-time data have been collected from a Kamsarmax vessel to build a hybrid marine power distribution plant model for simulating six system designs. A Multi-Criteria Decision Making (MCDM) methodology ranks the scenarios depending on environmental benefits, economic performance, and system space requirements. The findings demonstrate that the hybrid configurations, including solid oxide (SOFC) and proton exchange (PEMFC) FCs, achieve a deduction in equivalent CO₂ of the plant up to 91.79% and decrease the EEXI and the average CII by 10.24% and 6.53%, respectively. Although SOFC-included configurations show slightly better economic performance and require less fuel capacity, the overall performance of PEMFC designs are ranked higher in MCDM analysis due to the higher power density. Full article

The growing use of proton-exchange membrane fuel cells (PEMFCs) in hybrid propulsion systems is aimed at replacing traditional internal combustion engines and reducing greenhouse gas emissions. Effective power distribution between the fuel cell and the energy storage system (ESS) is crucial and has led to a growing emphasis on developing energy management systems (EMSs) to efficiently implement this integration. To address this goal, this study examines the performance of a fuzzy logic rule-based strategy for a hybrid fuel cell propulsion system in a small hydrogen-powered passenger vessel. The primary objective is to optimize fuel efficiency, with particular attention on reducing hydrogen consumption. The analysis is carried out under typical operating conditions encountered during a river trip. Comparisons between the proposed strategy with other approaches—control based, optimization based, and deterministic rule based—are conducted to verify the effectiveness of the proposed strategy. Simulation results indicated that the EMS based on fuzzy logic mechanisms was the most successful in reducing fuel consumption. The superior performance of this method stems from its ability to adaptively manage power distribution between the fuel cell and energy storage systems. Full article

This work focuses on the modeling of a zero-emissions, high-speed catamaran ferry employing a full-electric propulsion system. It addresses the global emphasis on full-electric vessels to align with IMO regulations regarding ship emissions and energy efficiency improvement. Using the AVL Cruise-M software, this research verified the implementation of an onboard fuel cell power-generating system integrated with a propulsion plant, aiming to assess its dynamic performance under load variations. The catamaran was 30 m long and 10 m wide with a cruise speed of 20 knots. The power system consisted of a proton-exchange membrane fuel cell (PEM) system, with a nominal power of 1600 kWe, a battery pack with a capacity of 2 kWh, two 777 kW electric motors, and their relative balance of the plant (BoP) subsystems. The simulation results show that the battery effectively supported the PEM during the maneuvering phase, enhancing its overall performance and energy economy. Full article

In terms of energy generation and consumption, ships are autonomous isolated systems, with power demands varying according to the type of ship: passenger or commercial. The power supply in modern ships is based on thermal engines-generators, which use fossil fuels, marine diesel oil (MDO) and liquefied natural gas (LNG). The continuous operation of thermal engines on ships during cruises results in increased emissions of polluting gases, mainly CO/CO₂. The combination of renewable energy sources (REs) and triple-fuel diesel engines (TFDEs) can reduce CO/CO₂ emissions, resulting in a “greener” interaction between ships and the ecosystem. This work presents a new control method for balancing the power generation and the load demands of a ship equipped with TFDEs, fuel cells (FCs), and REs, based on a real and accurate model of a super-tanker and simulation of its operation in real cruise conditions. The new TFDE technology engines are capable of using different fuels (marine diesel oil, heavy fuel oil and liquified natural gas), producing the power required for ship operation, as well as using compositions of other fuels based on diesel, aiming to reduce the polluting gases produced. The energy management system (EMS) of a ship is designed and implemented in the structure of a finite state machine (FSM), using the logical design of transitions from state to state. The results demonstrate that further reductions in fossil fuel consumption as well as CO₂ emissions are possible if ship power generation is combined with FC units that consume hydrogen as fuel. The hydrogen is produced locally on the ship through electrolysis using the electric power generated by the on-board renewable energy sources (REs) using photovoltaic systems (PVs) and wind energy conversion turbines (WECs). Full article

In this study, real voyage data and ship specifications of a general cargo ship are employed, and it is assumed that diesel generators are replaced with hydrogen proton exchange membrane fuel cells. The effect of the replacement on CO₂, NO_X, SO_X, and PM emissions and the CII value is calculated. Emission calculations show that there is a significant reduction in emissions when hydrogen fuel cells are used instead of diesel generators on the case ship. By using hydrogen fuel cells, there is a 37.4% reduction in CO₂ emissions, 32.5% in NO_X emissions, 37.3% in SO_X emissions, and 37.4% in PM emissions. If hydrogen fuel cells are not used instead of diesel generators, the ship will receive an A rating between 2023 and 2026, a B rating in 2027, a C rating in 2028–2029, and an E rating in 2030. On the other hand, if hydrogen fuel cells are used, the ship will always remain at an A rating between 2023 and 2030. The capital expenditure (CAPEX) and operational expenditure (OPEX) of the fuel cell system are USD 1,305,720 and USD 2,470,320, respectively, for a 15-year lifetime, and the hydrogen fuel expenses are competitive at USD 260,981, while marine diesel oil (MDO) fuel expenses are USD 206,435. Full article

This study introduced the methodology for integrating ethylene glycol/water mixture (GW) systems which supply heat energy to the liquid hydrogen (LH₂) fuel gas supply system (FGSS), and manage the temperature conditions of the battery system. All systems were designed and simulated based on the power demand of a 2 MW class platform supply vessel assumed as the target ship. The LH2 FGSS model is based on Aspen HYSYS V11 and the cell model that makes up the battery system is implemented based on a Thevenin model with four parameters. Through three different simulation cases, the integrated GW system significantly reduced electric power consumption for the GW heater during ship operations, achieving reductions of 1.38% (Case 1), 16.29% (Case 2), and 27.52% (Case 3). The energy-saving ratio showed decreases of 1.86% (Case 1), 21.01% (Case 2), and 33.80% (Case 3) in overall energy usage within the GW system. Furthermore, an examination of the battery system’s thermal management in the integrated GW system demonstrated stable cell temperature control within ±3 K of the target temperature, making this integration a viable solution for maintaining normal operating temperatures, despite relatively higher fluctuations compared to an independent GW system. Full article

This study proposed a deep reinforcement learning-based energy management strategy (DRL-EMS) that can be applied to a hybrid electric ship propulsion system (HSPS) integrating liquid hydrogen (LH₂) fuel gas supply system (FGSS), proton-exchange membrane fuel cell (PEMFC) and lithium-ion battery systems. This study analyzed the optimized performance of the DRL-EMS and the operational strategy of the LH₂-HSPS. To train the proposed DRL-EMS, a reward function was defined based on fuel consumption and degradation of power sources during operation. Fuel consumption for ship propulsion was estimated with the power for balance of plant (BOP) of the LH₂ FGSS and PEMFC system. DRL-EMS demonstrated superior global and real-time optimality compared to benchmark algorithms, namely dynamic programming (DP) and sequential quadratic programming (SQP)-based EMS. For various operation cases not used in training, DRL-EMS resulted in 0.7% to 9.2% higher operating expenditure compared to DP-EMS. Additionally, DRL-EMS was trained to operate 60% of the total operation time in the maximum efficiency range of the PEMFC system. Different hydrogen fuel costs did not affect the optimized operational strategy although the operating expenditure (OPEX) was dependent on the hydrogen fuel cost. Different capacities of the battery system did not considerably change the OPEX. Full article

Over the years, attention to climate change has meant that international agreements have been drawn up and increasingly stringent regulations aimed at reducing the environmental impact of the marine sector have been issued. A possible alternative technology to the conventional and polluting diesel internal combustion engines is represented by the Fuel Cells. In the present article, the preliminary design of two energy systems based on Solid Oxide Fuel Cells (SOFCs) fed by bio-methane was carried out for a particular cruise ship. The SOFC systems were sized to separately supply the electric energies required for the ship propulsion and to power the other ship electrical utilities. The SOFC systems operate in nominal conditions at constant load and other electrical storage systems (batteries) cover the fluctuations in the electrical energy demand. Furthermore, the heat produced by the SOFCs is exploited for co-/tri-generation purposes, to satisfy the ship thermal energy needs. The preliminary design of the new energy systems was made using electronic spreadsheets. The new energy system has obtained the primary energy consumption and CO₂ emissions reductions of 12.74% and 40.23% compared to the conventional energy system. Furthermore, if bio-methane is used, a reduction of 95.50% could be obtained in net CO₂ emissions. Full article

The use of green energy to power ships in the marine industry has attracted increasing attention in recent years. This paper presents an inland river cruise ship supplied by a fuel cell (FC) as the main power source and a supercapacitor (SC) as the auxiliary power source. Its propulsion inverter adopts the proposed high-boost Z-source inverter, and the proposed high-voltage-boost Z-source inverter (HVB-ZSI) principle is studied. The advantages of this proposed HVB-ZSI in two cases are verified through simulation. In case 1, it can be seen that the capacitance voltage is only 250 V, and the maximum inductance’s inrush current at the start is less than 200 A. But the capacitance voltage of HVB-ZSI reaches 383 V, and the inrush current is 300 A. While considering different constraints of the propulsion system, four operating modes for the set of the FC and SC are proposed. The small-signal model of the propulsion system is derived, and the control strategy is studied. By controlling the shoot-through duty cycle and modulation factor, the FC power, output power, and state of charge (SOC) of the SC can be controlled. Finally, to verify the performance of the proposed propulsion system, a hybrid power ship prototype equipped with a 7.5 kw propulsion motor is constructed. Four modes of the entire system are simulated by MATLAB/SIMULINK, and its performance is analyzed with experimental results. These results show that the new Z-source propulsion system has a promising application in new energy ships, as it has higher reliability and lower complexity and cost compared to conventional propulsion systems. Full article

The ship industry is currently facing numerous challenges, including rising fuel prices, limited fuel resources, and increasingly strict regulations related to energy efficiency and pollutant emissions. In this context, the adoption of green-ship wind–photovoltaic–electricity–fuel multi-energy supply systems has emerged as an efficient and clean technology that harnesses multiple energy sources. These systems have the potential to increase the utilization of renewable energy in ship operations while optimizing management practices in order to enhance overall energy efficiency. To address these challenges, this article presents a comprehensive energy supply system for ships that integrates multi-energy sources for cold–heat–electricity supply. The primary components of this system include fuel cells, photovoltaic equipment, wind turbines, electric heating pumps, electric refrigerators, thermal refrigerators, batteries, and heat storage tanks. By ensuring the safety of the system, our approach aims to minimize daily operating costs and optimize the performance of the multi-energy flow system by running scheduling models. To achieve this, our proposed system utilizes dynamic planning techniques combined with ship navigation conditions to establish an optimized management model. This model facilitates the coordinated distribution of green ship electricity, thermal energy, and cooling loads. The results of our study demonstrate that optimized management models significantly reduce economic costs and improve the stability of energy storage equipment. Specifically, through an analysis of the economic benefits of power storage and heat storage tanks, we highlight the potential for reducing fuel consumption by 6.0%, 1.5%, 1.4%, and 2.9% through the use of electric–thermal hybrid energy storage conditions. Full article

The combination of transportation electrification and clean energy in the shipping industry has been a hot topic, and related applications of hybrid all-electric ships (AESs) have emerged recently. However, it has been found that ship efficiency will be negatively impacted by improper component size and operation strategy. Therefore, the bilevel optimal sizing and operation method for the fuel cell/battery hybrid AES is proposed in this paper. This method optimizes the sizing of the AES while considering joint optimal energy management and voyage scheduling. The sizing problem is formulated at the upper level, and the joint scheduling problem is described at the lower level. Then, multiple cases are simulated to verify the effectiveness of the proposed method on a passenger ferry, and the results show that a 5.3% fuel saving and 5.2% total cost reduction can be achieved. Correspondingly, the ship’s energy efficiency is improved. This approach also can be used in similar vessels to enhance their overall performance and sustainability. Full article

The present work considers a 12 MW Solid Oxide Fuel Cell (SOFC) power plant integrated with a heat recovery system installed on board an LNG-fuelled cruise ship of about 175,000 gross tonnes and 345 m in length. The SOFC plant is fed by LNG and generates electrical power within an integrated power system configuration; additionally, it provides part of the thermal energy demand. A zero-dimensional (0D) Aspen Plus model has been built-up to simulate the SOFC power plant and to assess the performances of the proposed heat recovery system. The model has been validated by comparing the results obtained with data from the literature and commercial SOFC modules. The integrated system has been optimized in order to maximize steam production since it is the most requested thermal source on board. The main design outcome is that the steam produced is made by the recovered water from the SOFC exhaust by about 50–60%, thus reducing the onboard water storage or production. Additionally, results indicate that such an integrated system could save up to about 14.4% of LNG. Full article