Nowadays, sea traveling is increasing due to its practicality and low-cost. Ferry boats play a significant role in the marine tourism industry to transfer passengers and tourists. Nevertheless, traditional ferry ships consume massive amounts of fossil fuels to generate the required energy for their motors and demanded loads. Also, by consuming fossil fuels, ferries spatter the atmosphere with CO2 emissions and detrimental particles. In order to address these issues, ferry-building industries try to utilize renewable energy sources (RESs) and energy storage systems (ESSs), instead of fossil fuels, to provide the required power in the ferry boats. In general, full-electric ferry (FEF) boats are a new concept to reduce the cost of fossil fuels and air emissions. Hence, FEF can be regarded as a kind of dc stand-alone microgrid with constant power loads (CPLs). This article proposes a new structure of a FEF ship based on RESs and ESSs. In order to solve the negative impedance induced instabilities in dc power electronic based RESs, a new intelligent single input interval type-2 fuzzy logic controller based on sliding mode control is proposed for the dc-dc converters feeding CLPs. The main feature of the suggested technique is that it is mode-free and regulates the plant without requiring the knowledge of converter dynamics. Finally, we conduct a dSPACE-based real-time experiment to examine the effectiveness of the proposed energy management system for FEF vessels.
The paper presents a comprehensive review of the current status of integrated high temperature proton exchange membrane fuel cell (HT-PEMFC) and methanol steam reformer (MSR) systems. It highlights the advantages and limitations of the technology and outlines key areas for future improvement. A thorough discussion of novel reformer designs and optimizations aimed at improving the performance of the reformer, as well as different integrated MSR-HT-PEMFC system configurations are provided. The control strategies of the system operation and system diagnosis are also addressed, offering a complete picture of the integrated system design. The review revealed that several processes and components of the system should be improved to facilitate large-scale implementation of the MSR-HT-PEMFC systems. The lengthy system startup is one area that requires improvements. A structural design that is more compact without sacrificing performance is also required, which could possibly be achieved by recovering water from the fuel cell to fulfill MSR's water needs and consequently shrink the fuel tank. Reformer design should account for both heat transfer optimizations and reduced pressure drop to enhance the system's performance. Finally, research must concentrate on membrane materials for HT-PEMFC that can operate in the 200–300 °C temperature range and catalyst materials for more efficient MSR process at lower temperature should be investigated to improve the heat integration and overall system efficiency.
Waiting times for trucks, trains, airplanes and ships in service represent apparent transport system inefficiencies, and measures to reduce these may have the potential to abate transport GHG emissions. In international shipping, transportation researchers have pointed out that reduced waiting time in association with port calls holds such promise. We explore the potential for GHG abatement through port call optimization, focusing on crews and their employers - the shipping companies. Adding new empirical evidence to the transportation literature, we confirm the existence of idle time during port calls, and go beyond this in describing the causes for it. We show how several port stakeholders, including government officials, limit the crews’ and shipping companies’ room for maneuver in relation to port calls. We also show why the process of reducing waiting time in shipping is more complex than that for onshore transport modes, where real-time traffic information guides drivers’ route choices, and reduces congestion and waiting time. Our findings have implications for both policy makers and transportation research.
The hybrid combination of hydrogen fuel cells (FCs) and batteries has emerged as a promising solution for efficient and eco-friendly power supply in maritime applications. Yet, ensuring high-quality and cost-effective energy supply presents challenges. Addressing these goals requires effective coordination among multiple FC stacks, batteries, and cold-ironing. Although there has been previous work focusing it, the unique maritime load characteristics, variable cruise plans, and diverse fuel cell system architectures introduce additional complexities and therefore worth to be further studied. Motivated by it, a two-layer energy management system (EMS) is presented in this paper to enhance shipping fuel efficiency. The first layer of the EMS, executed offline, optimizes day-ahead power generation plans based on the vessel's next-day cruises. To further enhance the EMS's effectiveness in dynamic real-time situations, the second layer, conducted online, dynamically adjusts power splitting decisions based on the output from the first layer and instantaneous load information. This dual-layer approach optimally exploits the maritime environment and the fuel cell features. The presented method provides valuable utility in the development of control strategies for hybrid powertrains, thereby enabling the optimization of power generation plans and dynamic adjustment of power splitting decisions in response to load variations. Through comprehensive case studies, the effectiveness of the proposed EMS is evaluated, thereby showcasing its ability to improve system performance, enhance fuel efficiency (potential fuel savings of up to 28%), and support sustainable maritime operations.
Profitable energy saving measures are often not fully implemented in shipping, causing energy efficiency gaps. The paper identifies energy efficiency gaps in ship operations, and explores their causes. Lack of information on energy efficiency, lack of energy training at sea and onshore and lack of time to produce and provide reliable energy efficiency information cause energy efficiency gaps. The paper brings together the energy efficiency and ship management literatures, demonstrating how ship management models influence energy efficiency in ship operations. Achieving energy efficiency in ship operations is particularly challenging under third party ship management. Finally, the paper discusses management implications for shipping companies, which outsource ship management to third parties.
Solid-state lithium battery (SSLB) is considered as the most potential energy storage device in the next generation energy system due to its excellent safety performance. However, there are still intimidating safety issues for the SSLB, due to it being still in the development stage. This paper gives an overview of the safety of SSLBs. First, advanced solid-state battery techniques are introduced. Second, the safety issues of SSLBs are discussed. Then, the safety enhancement techniques are provided. Finally, future research opportunities are presented. This paper aims to provide a reference for researchers in the fields of electronic and electrical engineering who want to make some efforts in SSLB safety.
Large and remote offshore wind farms (OWFs) usually use voltage source converter (VSC) systems to transmit electrical power to the main network. Submarine high-voltage direct current (HVDC) cables are commonly used as transmission links. As they are liable to insulation breakdown, fault location in the HVDC cables is a major issue in these systems. Exact fault location can significantly reduce the high cost of submarine HVDC cable repair in multi-terminal networks. In this paper, a novel method is presented to find the exact location of the DC faults. The fault location is calculated using extraction of new features from voltage signals of cables' sheaths and a trained artificial neural network (ANN). The results obtained from a simulation of a three-terminal HVDC system in power systems computer-aided design (PSCAD) environment show that the maximum percentage error of the proposed method is less than 1%.
In this paper, a novel configuration of a pumped thermal electricity storage system is proposed which can integrate excess thermal energy from different renewable thermal energy sources, e.g. concentrated solar power, waste heat and deep geothermal energy plants, as well as excess electricity from direct electricity generating renewable energy sources, e.g. solar photovoltaic and wind energy plants. The proposed configuration can also be used as a retrofit option to existing conventional fossil fuel-based power plants. A conventional two-tank sensible heat storage is used as a thermal energy storage system that can be charged using direct renewable thermal energy and using a heat pump utilizing excess electricity. Different discharging cycles, including a Joule–Brayton system and a conventional steam Rankine cycle system, can be used. The proposed system can achieve a higher capacity factor compared to those of stand-alone plants.
As a case study, a conventional two-tank molten salt-based thermal energy storage system integrating concentrated solar power, considering a heliostat system, and a solar photovoltaic plant is investigated. The overall operational strategy of the plant was developed and based on that annual simulations were performed for a selected configuration. The results of the case study suggest that for a given requirement of capacity factor, the final selection of the capacities of the solar photovoltaic plant, heat pump and heliostat field should be done based on the minimum levelized cost of energy. Moreover, for high capacity factor requirements, the proposed configuration is promising.
This paper analyzes the nonlinear forces on a moored point-absorbing wave energy converter (WEC) in resonance at prototype scale (1:1) and at model scale (1:16). Three simulation types were used: Reynolds Averaged Navier-Stokes (RANS), Euler and the linear radiation-diffraction method (linear). Results show that when the wave steepness is doubled, the response reduction is: (i) 3% due to the nonlinear mooring response and the Froude-Krylov force; (ii) 1-4% due to viscous forces; and (iii) 18-19% due to induced drag and non-linear added mass and radiation forces. The effect of the induced drag is shown to be largely scale-independent. It is caused by local pressure variations due to vortex generation below the body, which reduces the total pressure force on the hole. Euler simulations are shown to be scale-independent and the scale effects of the WEC are limited by the purely viscous contribution (1-4%) for the two waves studied. We recommend that experimental model scale test campaigns of WECs should be accompanied by RANS simulations, and the analysis complemented by scale-independent Euler simulations to quantify the scale-dependent part of the nonlinear effects.
Existing energy management strategies (EMSs) for hybrid power systems (HPSs) in hydrogen fuel cell vessels (FCVs) are not applicable to scenarios with multiple hydrogen fuel cells (FCs) and lithium batteries (LBs) in parallel, and are difficult to achieve real-time control and optimization for multiple objectives. In this paper, a bi-layer real-time energy management strategy (BLRT-EMS) is proposed. Compared with existing EMSs, the proposed BLRT-EMS implements different control/optimization objectives distributed in the execution layer EMS (EL-EMS) and the decision layer EMS (DL-EMS), which can significantly reduce bus voltage fluctuations, decrease hydrogen consumptions, improve the system efficiency, and have potential for engineering applications. In the first EL-EMS, a decentralized optimal power allocation strategy is proposed, which allows each FC system to allocate the output power ratio according to their generation costs, ensuring consistent performance of multiple FC systems (MFCS) under long-term operating conditions, and thus delaying the degradation rate of FCs. In the second EL-EMS, a distributed cooperative control strategy is proposed to achieve dynamic SoC equalization, proportional output power allocation, and accurate bus voltage restoration among multiple battery storage systems (MBSS) to extend the service life of batteries. In the DL-EMS, an energy coordination optimization strategy between MFCS and MBSS is proposed to achieve hydrogen consumption reduction and system efficiency improvement, thus enhancing the endurance performance of FCV. Finally, test results based on the StarSim experimental platform show that the proposed BLRT-EMS has faster SoC convergence speed, smaller bus voltage deviation, lower hydrogen consumption, higher system efficiency, and lower operation stress than the state-of-the-art methods.