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Energies
Volume 18
Issue 8
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Energies, Volume 18, Issue 8 (April-2 2025) – 271 articles

Cover Story (view full-size image): This article demonstrates the impact of blending diesel fuel with tire pyrolysis oil (TPO) on rheological properties and compliance with legal fuel requirements. Tests were conducted on blends of normative D100 diesel oil with 5, 7, 10, 15, and 20% m/m TPO. Reference measurements were also performed for pure diesel and pure pyrolysis oil. The kinematic viscosity, density, dynamic viscosity, viscosity index, pour point, cloud point, and cold filter plugging point were determined. Densities were measured at 15–100 °C and viscosities at 20, 40, and 100 °C. Approximating models were built for all analyzed parameters and can be used in future studies. Results were compared with limit values specified in selected standards and regulations. Blends with 0–20% TPO met marine distillate fuel standards, while blends with up to 7% TPO complied with Polish diesel fuel regulations. View this paper
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40 pages, 4760 KiB  
Review
Sustainable Electric Micromobility Through Integrated Power Electronic Systems and Control Strategies
by Mohamed Krichi, Abdullah M. Noman, Mhamed Fannakh, Tarik Raffak and Zeyad A. Haidar
Energies 2025, 18(8), 2143; https://doi.org/10.3390/en18082143 - 21 Apr 2025
Abstract
A comprehensive roadmap for advancing Electric Micromobility (EMM) systems addressing the fragmented and scarce information available in the field is defined as a transformative solution for urban transportation, targeting short-distance trips with compact, lightweight vehicles under 350 kg and maximum speeds of 45 [...] Read more.
A comprehensive roadmap for advancing Electric Micromobility (EMM) systems addressing the fragmented and scarce information available in the field is defined as a transformative solution for urban transportation, targeting short-distance trips with compact, lightweight vehicles under 350 kg and maximum speeds of 45 km/h, such as bicycles, e-scooters, and skateboards, which offer flexible, eco-friendly alternatives to traditional transportation, easing congestion and promoting sustainable urban mobility ecosystems. This review aims to guide researchers by consolidating key technical insights and offering a foundation for future exploration in this domain. It examines critical components of EMM systems, including electric motors, batteries, power converters, and control strategies. Likewise, a comparative analysis of electric motors, such as PMSM, BLDC, SRM, and IM, highlights their unique advantages for micromobility applications. Battery technologies, including Lithium Iron Phosphate, Nickel Manganese Cobalt, Nickel-Cadmium, Sodium-Sulfur, Lithium-Ion and Sodium-Ion, are evaluated with a focus on energy density, efficiency, and environmental impact. The study delves deeply into power converters, emphasizing their critical role in optimizing energy flow and improving system performance. Furthermore, control techniques like PID, fuzzy logic, sliding mode, and model predictive control (MPC) are analyzed to enhance safety, efficiency, and adaptability in diverse EMM scenarios by using cutting-edge semiconductor devices like Silicon Carbide (SiC) and Gallium Nitride (GaN) in well-known configurations, such as buck, boost, buck–boost, and bidirectional converters to ensure great efficiency, reduce energy losses, and ensure compact and reliable designs. Ultimately, this review not only addresses existing gaps in the literature but also provides a guide for researchers, outlining future research directions to foster innovation and contribute to the development of sustainable, efficient, and environmentally friendly urban transportation systems. Full article
(This article belongs to the Special Issue Future of Transport: Hybrid Electrification and Hydrogen Integration in Vehicles and Infrastructure)
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18 pages, 5370 KiB  
Article
Diagnosis of Stator Inter-Turn Short Circuit Faults in Synchronous Machines Based on SFRA and MTST
by Junsheng Ding and Zhongyong Zhao
Energies 2025, 18(8), 2142; https://doi.org/10.3390/en18082142 - 21 Apr 2025
Abstract
As a key component of the power system, the good or bad conditions of synchronous machines will directly affect the stable supply of electric energy. The inter-turn short fault of the stator is one of the main dangers to the synchronous machine and [...] Read more.
As a key component of the power system, the good or bad conditions of synchronous machines will directly affect the stable supply of electric energy. The inter-turn short fault of the stator is one of the main dangers to the synchronous machine and is difficult to diagnose. Frequency response analysis has recently been introduced and used for detecting this type of fault; however, the fault degrees and locations cannot be directly recognized by traditional frequency response analysis. Therefore, this study improves the frequency response analysis by combining it with a deep learning model of a multivariate time series transformer. First, the principle of this study is introduced. Second, the frequency response data of short circuit faults are obtained using an artificially simulated experimental platform of a synchronous machine. The deep learning model is then well-trained. Finally, the performance of the proposed method is tested and verified. It concludes that the proposed method has the potential for classifying and diagnosing the inter-turn short circuit of stators in synchronous machines. Full article
(This article belongs to the Special Issue Condition Monitoring of Electrical Machines Based on Models)
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23 pages, 1875 KiB  
Article
Optimal Adjustment of Reactive Power in Transmission Systems by Variation of Taps in Static Elements Using the Mean-Variance Mapping Optimization Algorithm
by Diego Cevallos, Carlos Barrera-Singaña and Hugo Arcos
Energies 2025, 18(8), 2141; https://doi.org/10.3390/en18082141 - 21 Apr 2025
Abstract
This work focuses on the problem of optimal reactive power adjustment (ORPA) in electric power systems (EPSs) by implementing the Mean-Variance Mapping Algorithm (MVMO) focusing on the control of static devices such as taps in transformers and static capacitor banks. The study focuses [...] Read more.
This work focuses on the problem of optimal reactive power adjustment (ORPA) in electric power systems (EPSs) by implementing the Mean-Variance Mapping Algorithm (MVMO) focusing on the control of static devices such as taps in transformers and static capacitor banks. The study focuses on IEEE test systems of 39 and 118 buses using MATLAB R2024b together with the MATPOWER toolbox. The main novelty lies in the application of the MVMO algorithm to solve the ORPA problem considering only static control elements, which allows an efficient and practical solution with lower computational complexity; through statistical analysis, the performance of each of the algorithms was evaluated where it was experimentally shown that MVMO presents a better performance in terms of reducing active power losses and improving voltage profiles compared to the PSO algorithm. Full article
(This article belongs to the Section F: Electrical Engineering)
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33 pages, 1233 KiB  
Review
Silicon Carbide Converter Design: A Review
by Asif Rasul, Rita Teixeira and José Baptista
Energies 2025, 18(8), 2140; https://doi.org/10.3390/en18082140 - 21 Apr 2025
Abstract
To achieve lower switching losses and higher frequency capabilities in converter design, researchers worldwide have been investigating Silicon carbide (SiC) modules and MOSFETs. In power electronics, wide bandgap devices such as Silicon carbide are essential for creating more efficient, higher-density, and higher-power-rated converters. [...] Read more.
To achieve lower switching losses and higher frequency capabilities in converter design, researchers worldwide have been investigating Silicon carbide (SiC) modules and MOSFETs. In power electronics, wide bandgap devices such as Silicon carbide are essential for creating more efficient, higher-density, and higher-power-rated converters. Devices like SiC and Gallium nitride (GaN) offer numerous advantages in power electronics, particularly by influencing parasitic capacitance and inductance in printed circuit boards (PCBs). A review paper on Silicon carbide converter designs using coupled inductors provides a comprehensive analysis of the advancements in SiC-based power converter technologies. Over the past decade, SiC converter designs have demonstrated both efficiency and reliability, underscoring significant improvements in performance and design methodologies over time. This review paper examines developments in Silicon carbide converter design from 2014 to 2024, with a focus on the research conducted in the past ten years. It highlights the advantages of SiC technology, techniques for constructing converters, and the impact on other components. Additionally, a bibliometric analysis of prior studies has been conducted, with a particular focus on strategies to minimize switching losses, as discussed in the reviewed articles. Full article
(This article belongs to the Special Issue Energy, Electrical and Power Engineering: 3rd Edition)
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29 pages, 4367 KiB  
Article
Wind Resource Assessment for Potential Wind Turbine Operations in the City of Yanbu, Saudi Arabia
by Makbul A. M. Ramli and Houssem R. E. H. Bouchekara
Energies 2025, 18(8), 2139; https://doi.org/10.3390/en18082139 - 21 Apr 2025
Abstract
Energy generated from wind (in the form of wind farms (WFs)) is expected to help alleviate rising energy demand in Saudi Arabia, driven by industrial development and population growth. However, before implementing wind farms, conducting a comprehensive wind resource assessment (WRA) study is [...] Read more.
Energy generated from wind (in the form of wind farms (WFs)) is expected to help alleviate rising energy demand in Saudi Arabia, driven by industrial development and population growth. However, before implementing wind farms, conducting a comprehensive wind resource assessment (WRA) study is of paramount importance. This paper presents the analysis of the wind resource potential of a site in Yanbu city, which is located on the western coastal area of Saudi Arabia, using a comprehensive study. The hourly data on wind speed and direction over a one-year period was used in the presented analysis. The plant capacity factor (CF) and annual energy production (AEP) are evaluated for more than 100 commercial wind turbines (WTs). The highest AEP was achieved by the ‘Enercon E126/7.5 MW’ turbine, generating 14.49 GWh, with a corresponding CF of 21.82%. In contrast, the lowest AEP was observed for the ‘Northern Power d’ turbine, producing only 0.13 GWh, with a CF of 14.89%. The highest CF was recorded for the ‘Leitwind LTW104/2.0 MW’ turbine at 40.67%, corresponding to an AEP of 7.12 GWh. The results obtained are very valuable for designers in selecting the appropriate WT to obtain the predicted AEP and CF with the appropriate turbine class. Furthermore, this study applied the K-means clustering algorithm to classify WTs into three distinct categories. Building on this classification, synthetic datasets representing tailored WT configurations were generated—a novel methodology that enables the simulation of site-specific designs not yet available in existing market offerings. These datasets equip wind farm developers with the ability to define WT specifications for manufacturers, guided by two key criteria: the site’s wind resource profile and the target performance metrics of the WT. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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22 pages, 9821 KiB  
Article
Edge–Cloud Intelligence for Sustainable Wind Turbine Blade Transportation: Machine-Vision-Driven Safety Monitoring in Renewable Energy Systems
by Yajun Wang, Xiaodan Wang, Yihai Wang and Shibiao Fang
Energies 2025, 18(8), 2138; https://doi.org/10.3390/en18082138 - 21 Apr 2025
Abstract
The transportation of wind turbine blades in remote wind farm areas poses significant safety risks to both personnel and infrastructure. These risks arise from collision hazards, complex terrain, and the difficulty of real-time monitoring under adverse environmental conditions. To address these challenges, this [...] Read more.
The transportation of wind turbine blades in remote wind farm areas poses significant safety risks to both personnel and infrastructure. These risks arise from collision hazards, complex terrain, and the difficulty of real-time monitoring under adverse environmental conditions. To address these challenges, this study proposes an intelligent safety monitoring framework that combines machine vision with edge–cloud collaboration. The framework employs an optimized YOLOv7-Tiny model. It is enhanced with convolutional block attention modules (CBAMs) for feature refinement, CARAFE upsampling for better contextual detail, and bidirectional feature pyramid networks (BiFPNs) for multi-scale object detection. The system was validated at the Lingbi Wind Farm in China. It achieved over 95% precision in detecting safety violations, such as unauthorized vehicle intrusions and personnel proximity violations within 2 m, while operating at 48 frames per second. The edge–cloud architecture reduces latency by 30% compared to centralized systems. It enables alert generation within 150 milliseconds. Dynamic risk heatmaps derived from real-time data help reduce collision probability by 42% in high-risk zones. Enhanced spatial resolution further minimizes false alarms in mountainous areas with poor signal conditions. Overall, these improvements reduce operational downtime by 25% and lower maintenance costs by 18% through proactive hazard mitigation. The proposed framework provides a scalable and energy-efficient solution for safety enhancement in renewable energy logistics. It balances computational performance with flexible deployment and addresses key gaps in intelligent monitoring for large-scale wind energy projects. This work offers valuable insights for sustainable infrastructure management. Full article
(This article belongs to the Special Issue Advancements in Wind Farm Design and Optimization)
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22 pages, 3503 KiB  
Article
An FMEA Assessment of an HTR-Based Hydrogen Production Plant
by Lorenzo Damiani, Francesco Novarini and Guglielmo Lomonaco
Energies 2025, 18(8), 2137; https://doi.org/10.3390/en18082137 - 21 Apr 2025
Abstract
The topic of hydrogen as an energy vector is widely discussed in the present literature, being one of the crucial technologies aimed at human carbon footprint reduction. There are different hydrogen production methods. In particular, this paper focuses on Steam Methane Reforming (SMR), [...] Read more.
The topic of hydrogen as an energy vector is widely discussed in the present literature, being one of the crucial technologies aimed at human carbon footprint reduction. There are different hydrogen production methods. In particular, this paper focuses on Steam Methane Reforming (SMR), which requires a source of high-temperature heat (around 900 °C) to trigger the chemical reaction between steam and CH4. This paper examines a plant in which the reforming heat is supplied through a helium-cooled high-temperature nuclear reactor (HTR). After a review of the recent literature, this paper provides a description of the plant and its main components, with a central focus on the safety and reliability features of the combined nuclear and chemical system. The main aspect emphasized in this paper is the assessment of the hydrogen production reliability, carried out through Failure Modes and Effects Analysis (FMEA) with the aid of simulation software able to determine the quantity and origin of plant stops based on its operational tree. The analysis covers a time span of 20 years, and the results provide a breakdown of all the failures that occurred, together with proposals aimed at improving reliability. Full article
(This article belongs to the Special Issue Advanced Technologies in Nuclear Engineering)
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20 pages, 4287 KiB  
Article
Molecular and Microstructural Engineering Strategies for High-Performance Polypropylene Insulation Materials
by Zhaoliang Xing, Hao Ge, Deshen Li, Shaowei Guo, Bo Yang, Chunjia Gao, Bo Qi and Jianhong Hao
Energies 2025, 18(8), 2136; https://doi.org/10.3390/en18082136 - 21 Apr 2025
Abstract
This study develops a high-performance polypropylene (PP) substrate platform by optimizing micro/macrostructures and introduces an efficient catalyst. Key findings include: (1) microstructural analysis identifies ash content impurities (>20 ppm) as triggers for partial discharge-induced insulation failure. PP molecular weights (105–106 [...] Read more.
This study develops a high-performance polypropylene (PP) substrate platform by optimizing micro/macrostructures and introduces an efficient catalyst. Key findings include: (1) microstructural analysis identifies ash content impurities (>20 ppm) as triggers for partial discharge-induced insulation failure. PP molecular weights (105–106) with narrower distributions enhance mechanical strength, while functional groups (-CH2/-CH3) show no structural variations across samples. (2) Macroscopically, mixed α-β crystal interfaces increase insulation failure risks, necessitating single-crystalline structures. Higher temperatures reduce dielectric constants but increase losses, requiring environmental consideration. Crystallinity positively correlates with DC breakdown strength (443.31 kV/mm at 54.13% crystallinity). (3) Among three endo-donor catalysts, the internal electron donor 3-based catalyst achieved optimal die-test activity (47.7 kg PP/g cat·h). With 20 mL triethylamine, the catalyst reduced PP ash content by 42.1%, narrowed molecular weight distribution by 31.6%, and increased crystallinity by 8.74%. These results establish microstructure–property relationships for PP capacitors and provide technical guidelines for performance enhancement. The work addresses current limitations in PP evaluation methods and offers a practical strategy for manufacturing high-insulation PP materials through structural control and catalytic optimization. Full article
(This article belongs to the Section F: Electrical Engineering)
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17 pages, 3434 KiB  
Article
Research and Engineering Practice of Var-Voltage Control in Primary and Distribution Networks Considering the Reactive Power Regulation Capability of Distributed PV Systems
by Haiyun Wang, Qian Chen, Linyu Zhang, Xiyu Yin, Zhijian Zhang, Huayue Wei and Xiaoyue Chen
Energies 2025, 18(8), 2135; https://doi.org/10.3390/en18082135 - 21 Apr 2025
Abstract
To fully utilize the reactive power resources of distributed photovoltaic (PV) systems, this study proposes a coordinated var-voltage control strategy for the main distribution network, incorporating the reactive power regulation capability of distributed PV. Firstly, the Automatic Voltage Control (AVC) tertiary and secondary [...] Read more.
To fully utilize the reactive power resources of distributed photovoltaic (PV) systems, this study proposes a coordinated var-voltage control strategy for the main distribution network, incorporating the reactive power regulation capability of distributed PV. Firstly, the Automatic Voltage Control (AVC) tertiary and secondary voltage control methods and optimization models in the main and distribution networks area are analyzed, and the physical equivalence of the reactive power compensation equipment involved is carried out. In this study, a coordinated local var-voltage control method is proposed, which integrates AVC primary voltage control and divides the control scheme into feeder and station areas, respectively. Through the analysis of actual operation cases in a regional power grid, the results demonstrate a reduction in network loss by 171.14 kW through voltage adjustment, validating the effectiveness of the proposed strategy. This method fully leverages the reactive power regulation capability of distributed renewable energy sources, reduces the operational frequency of reactive power equipment in substations, and synergizes with the AVC system to achieve optimal power grid operation. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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21 pages, 2477 KiB  
Article
Photovoltaic Hosting Capacity Assessment of Distribution Networks Considering Source–Load Uncertainty
by Chao Chen, Weifeng Peng, Cheng Xie, Shufeng Dong and Yibo Hua
Energies 2025, 18(8), 2134; https://doi.org/10.3390/en18082134 - 21 Apr 2025
Abstract
With the continuous expansion of distributed photovoltaic (PV) integration, the hosting capacity of distribution networks has become a critical issue in power system planning and operation. Under varying meteorological and load fluctuation conditions, traditional assessment methods often face adaptability and uncertainty handling challenges. [...] Read more.
With the continuous expansion of distributed photovoltaic (PV) integration, the hosting capacity of distribution networks has become a critical issue in power system planning and operation. Under varying meteorological and load fluctuation conditions, traditional assessment methods often face adaptability and uncertainty handling challenges. To enhance the practical applicability and accuracy of hosting capacity evaluations, this paper proposes a PV hosting capacity assessment model that incorporates source–load uncertainty and constructs an alternative scenario optimization evaluation framework driven by target-oriented scenario generation. The model considers system constraints and employs the sparrow search algorithm (SSA) to optimize the maximum PV hosting capacity. On the source side, PV output scenarios with temporal characteristics are generated based on the mapping relationship between meteorological factors and PV power. On the load side, historical data are employed to extract fluctuation ranges and to introduce random perturbations to simulate load uncertainty. In addition, a PV power scenario generation method based on the Wasserstein generative adversarial network with gradient penalty (WGAN-GP) is proposed, integrating physical-data dual-driven strategies to enhance the physical consistency of generated data, while incorporating a target-driven weighted sampling mechanism to improve its learning ability for key features. Case studies verify that the proposed method demonstrates strong adaptability and accuracy under varying meteorological and load conditions. Full article
(This article belongs to the Special Issue Application of Advanced Control Theories to Power Electronics and Power Systems: 2nd Edition)
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19 pages, 4865 KiB  
Article
An Adaptive Scheduling Method for Standalone Microgrids Based on Deep Q-Network and Particle Swarm Optimization
by Borui Zhang and Bo Liu
Energies 2025, 18(8), 2133; https://doi.org/10.3390/en18082133 - 21 Apr 2025
Abstract
Standalone wind–solar–diesel–storage microgrids serve as a crucial solution for achieving energy self-sufficiency in remote and off-grid areas, such as rural regions and islands, where conventional power grids are unavailable. Addressing scheduling optimization challenges arising from the intermittent nature of renewable energy generation and [...] Read more.
Standalone wind–solar–diesel–storage microgrids serve as a crucial solution for achieving energy self-sufficiency in remote and off-grid areas, such as rural regions and islands, where conventional power grids are unavailable. Addressing scheduling optimization challenges arising from the intermittent nature of renewable energy generation and the uncertainty of load demand, this paper proposes an adaptive optimization scheduling method (DQN-PSO) that integrates Deep Q-Network (DQN) with Particle Swarm Optimization (PSO). The proposed approach leverages DQN to assess the operational state of the microgrid and dynamically adjust the key parameters of PSO. Additionally, a multi-strategy switching mechanism, incorporating global search, local adjustment, and reliability enhancement, is introduced to jointly optimize both clean energy utilization and power supply reliability. Simulation results demonstrate that, under typical daily, high-volatility, and low-load scenarios, the proposed method improves clean energy utilization by 3.2%, 4.5%, and 10.9%, respectively, compared to conventional PSO algorithms while reducing power supply reliability risks to 0.70%, 1.04%, and 0.30%, respectively. These findings validate the strong adaptability of the proposed algorithm to dynamic environments. Further, a parameter sensitivity analysis underscores the significance of the dynamic adjustment mechanism. Full article
(This article belongs to the Section A1: Smart Grids and Microgrids)
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18 pages, 1016 KiB  
Article
Barriers to Balcony Solar and Plug-In Distributed Energy Resources in the United States
by Daniel L. Gerber, Achim Ginsberg-Klemmt, Lyn Stoler, Jordan Shackelford and Alan Meier
Energies 2025, 18(8), 2132; https://doi.org/10.3390/en18082132 - 21 Apr 2025
Abstract
Plug-in distributed energy resources (DERs), such as balcony solar, backfeed power to the home through a standard plug. These systems may represent the future of residential solar and storage, particularly as recent net metering policies have reduced the economic appeal of rooftop solar. [...] Read more.
Plug-in distributed energy resources (DERs), such as balcony solar, backfeed power to the home through a standard plug. These systems may represent the future of residential solar and storage, particularly as recent net metering policies have reduced the economic appeal of rooftop solar. While plug-in DERs have seen widespread success in Europe, their U.S. market is stagnant. This paper reviews the technical, interconnection, and regulatory barriers hindering the adoption of plug-in DERs. We first discuss the technical barriers, which include touch safety, breaker masking, and bidirectional ground-fault circuit interrupters. We then examine utility perspectives on plug-in DERs and strategies for navigating interconnection challenges. Finally, we discuss regulatory hurdles related to UL standards and the National Electrical Code. Full article
(This article belongs to the Special Issue Electronics for Energy Conversion and Renewables)
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20 pages, 9053 KiB  
Article
Comparable Study on Celadon Production Fueled by Methanol and Liquefied Petroleum Gas at Industry Scale
by Yihong Song, Shangbo Han, Teng Hu, Huajie Lyu, Nuo Chen, Xiao Zhang, Saisai Lin, Chenghang Zheng, Peng Liu and Xiang Gao
Energies 2025, 18(8), 2131; https://doi.org/10.3390/en18082131 - 21 Apr 2025
Abstract
As a major contributor to industrial energy consumption and carbon emissions, the kiln industry faces increasing pressure to adopt cleaner energy sources. This study investigated the combustion characteristics, redox processes in celadon firing, product quality, and pollutant emissions for an industry furnace with [...] Read more.
As a major contributor to industrial energy consumption and carbon emissions, the kiln industry faces increasing pressure to adopt cleaner energy sources. This study investigated the combustion characteristics, redox processes in celadon firing, product quality, and pollutant emissions for an industry furnace with methanol and liquefied petroleum gas (LPG) as kiln fuels. Methanol combustion reduced firing time by 17.4% due to the faster temperature rise during oxidation and holding phases and provided a more uniform and stable flame, compared with LPG cases. Significant reductions in emissions were observed when methanol is used as fuel. For example, NO concentration is reduced by 70.89%, 37.43% for SO2, 93.67% for CO, 45.07% for CO2, and 85.89% for CH4. The methanol-fired celadon exhibited better quality in terms of the appearance and threshold stress–strain value. The chemical analysis results show that K/O element ratio increased from 8.439% to 11.706%, Fe/O decreased from 4.793% to 3.735%, Al/O decreased from 33.445% to 31.696%, and Si/O increased from 76.169% to 89.825%. These findings demonstrate the potential of methanol as a sustainable kiln fuel, offering enhanced combustion efficiency, reduced emissions, and improved ceramic quality. Full article
(This article belongs to the Special Issue Advanced Combustion Technologies and Emission Control)
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14 pages, 7415 KiB  
Article
Enhancing Thermal Conductivity of SiC Matrix Pellets for Accident-Tolerant Fuel via Atomic Layer Deposition of Al2O3 Coating
by Yumeng Zhao, Wenqing Wang, Jiquan Wang, Xiao Liu, Yu Li, Zongshu Li, Rong Chen and Wei Liu
Energies 2025, 18(8), 2130; https://doi.org/10.3390/en18082130 - 21 Apr 2025
Abstract
This study investigates the enhancement of thermal conductivity in silicon carbide (SiC) matrix pellets for accident-tolerant fuels via atomic layer deposition (ALD) of alumina (Al2O3) coatings. Pressure-holding ALD protocols ensured precursor saturation, enabling precise coating control (0.09 nm/cycle). The [...] Read more.
This study investigates the enhancement of thermal conductivity in silicon carbide (SiC) matrix pellets for accident-tolerant fuels via atomic layer deposition (ALD) of alumina (Al2O3) coatings. Pressure-holding ALD protocols ensured precursor saturation, enabling precise coating control (0.09 nm/cycle). The ALD-coated Al2O3 layers on SiC particles were found to be more uniform while minimizing surface oxidation compared to traditional mechanical mixing. Combined with yttria (Y2O3) additives and spark plasma sintering (SPS), ALD-coated samples achieved satisfactory densification and thermal performance. Results demonstrated that 5~7 wt.% ALD-Al2O3 + Y2O3 achieved corrected thermal conductivity enhancements of 14~18% at 100 °C., even with reduced sintering aid content, while maintaining sintered densities above 92% T.D. (theoretical density). This work highlights ALD’s potential in fabricating high-performance, accident-tolerant SiC-based fuels for safer and more efficient nuclear reactors, with implications for future optimization of sintering processes and additive formulations. Full article
(This article belongs to the Section B4: Nuclear Energy)
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27 pages, 9572 KiB  
Article
Multi-Objective Optimization Research Based on NSGA-II and Experimental Study of Triplex-Tube Phase Change Thermal Energy Storage System
by Yi Zhang, Haoran Yu, Yingzhen Hou and Neng Zhu
Energies 2025, 18(8), 2129; https://doi.org/10.3390/en18082129 - 21 Apr 2025
Abstract
Energy storage technology is crucial for promoting the replacement of traditional energy with renewable energy and regulating the energy supply–demand relationship. This paper investigates a triplex-tube thermal energy unit storage to solve the intermediate heat storage and heat transfer problem of hot water [...] Read more.
Energy storage technology is crucial for promoting the replacement of traditional energy with renewable energy and regulating the energy supply–demand relationship. This paper investigates a triplex-tube thermal energy unit storage to solve the intermediate heat storage and heat transfer problem of hot water supply and demand in clean heating systems. A multi-objective optimization method based on the elitist non-dominated sorting genetic algorithm (NSGA-II) was utilized to optimize the geometric dimensions (inner tube radius r1, casing tube radius r2, and outer tube radius r3), focusing on heat transfer efficiency (ε), heat storage rate (Pt), and mass (M). On this basis, the influence of the optimization variables was analyzed. The optimized configuration (r1=0.014 m, r2=0.041 m, and r3=0.052 m) was integrated into a modular design, achieving a 2.12% improvement in heat transfer efficiency and a 73.23% increase in heat storage rate. Experimental results revealed that higher heat transfer fluid (HTF) temperatures significantly reduce heat storage time, while HTF flow rate has a minimal impact. Increasing the heat release temperature extends the phase change material (PCM) heat release duration, with the flow rate showing negligible effects. The system’s thermal supply capacity is susceptible to heat release temperature. Full article
(This article belongs to the Section J1: Heat and Mass Transfer)
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18 pages, 12535 KiB  
Article
A Synchronization of Permanent Magnet Synchronous Generator Dedicated for Small and Medium Hydroelectric Plants
by Adam Gozdowiak and Maciej Antal
Energies 2025, 18(8), 2128; https://doi.org/10.3390/en18082128 - 21 Apr 2025
Abstract
This article presents the simulation results of synchronization of a permanent magnet synchronous generator (PMSG) dedicated for a hydroelectric plant without power converter devices. The proposed machine design allows to connect a generator to the grid in two different ways. With the first [...] Read more.
This article presents the simulation results of synchronization of a permanent magnet synchronous generator (PMSG) dedicated for a hydroelectric plant without power converter devices. The proposed machine design allows to connect a generator to the grid in two different ways. With the first method, the machine is connected to the grid in a similar way as in the case of an electrically excited synchronous generator. The second method is a direct line-start process based on asynchronous torque—similar to asynchronous motor start. Both methods can be used alternately. The advantages of the presented design are elimination of converter devices for starting the PMSG, possibility of use in small and medium hydroelectric power plants, operation with a high efficiency and high power factor in a wide range of generated power, and smaller dimensions in comparison to the generators currently used. The described rotor design allows for the elimination of capacitor batteries for compensation of reactive power drawn by induction generators commonly used in small hydroelectric plants. In addition, due to the high efficiency of the PMSG, high power factor, and appropriately selected design, the starting current during synchronization is smaller than in the case of an induction generator, which means that the structural elements wear out more slowly, and thus, the generator’s service life is increased. In this work, it is shown that PMSG with a rotor cage should have permanent magnets with an increased temperature class in order to avoid demagnetization of the magnets during asynchronous start-up. In addition, manufacturers of such generators should provide the number of start-up cycles from cold and warm states in order to avoid shortening the service life of the machine. The main objective of the article is to present the methods of synchronizing a generator of such a design (a rotor with permanent magnets and a starting cage) and their consequences on the behavior of the machine. The presented design allows synchronization of the generator with the network in two ways. The first method enables synchronization of the generator with the power system by asynchronous start-up, i.e., obtaining a starting torque exceeding the braking torque from the magnets. The second method of synchronization is similar to the method used in electromagnetically excited generators, i.e., before connecting, the rotor is accelerated to synchronous speed by means of a water turbine, and then, the machine is connected to the grid by switching on the circuit breaker. This paper presents electromagnetic phenomena occurring in both cases of synchronization and describes the influence of magnet temperature on physical quantities. Full article
(This article belongs to the Section F: Electrical Engineering)
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35 pages, 3598 KiB  
Review
Green Synthesis of Core/Shell Phase Change Materials: Applications in Industry and Energy Sectors
by Aikaterini Feizatidou, Vassilios Binas and Ioannis A. Kartsonakis
Energies 2025, 18(8), 2127; https://doi.org/10.3390/en18082127 - 21 Apr 2025
Abstract
Engineered substances that demonstrate superior properties compared with conventional materials are called advanced materials. Thermal energy storage systems based on phase change materials (PCMs) offer an eco-friendly solution to reduce fuel and electricity consumption. PCMs are compounds that can store thermal energy in [...] Read more.
Engineered substances that demonstrate superior properties compared with conventional materials are called advanced materials. Thermal energy storage systems based on phase change materials (PCMs) offer an eco-friendly solution to reduce fuel and electricity consumption. PCMs are compounds that can store thermal energy in the form of latent heat during phase transitions. Green synthesis of core/shell composite PCMs is an environmentally friendly method for producing these materials, focusing on reducing energy consumption, minimizing the use of harmful chemicals, and utilizing biodegradable or sustainable materials. Green synthesis methods typically involve natural materials, solvent-free techniques, green solvents, biomimetic approaches, and energy-efficient processes. This review explores green synthesis methods like solvent-free techniques for core/shell PCMs production, highlighting their role in thermal regulation for energy-efficient buildings. Special attention is given to materials derived from biomass that can be used as precursors for PCM synthesis. Moreover, the principles of latent heat thermal energy storage systems with PCMs, in accordance with physical chemistry guidance, are also presented. Furthermore, materials that can be used as PCMs, along with the most effective methods for improving their thermal performance, as well as various passive applications in the building sector, are highlighted. Finally, the focus on the combination of environmentally friendly processes and the performance benefits of composite PCMs that offer a sustainable solution for thermal energy storage and management is also discussed. It was found that PCMs that are synthesized in a green way can reduce emissions and waste during production and disposal. Moreover, waste recycling and its use for another type of synthesis is also a potential green solution. Full article
(This article belongs to the Special Issue Biomass and Bio-Energy—2nd Edition)
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24 pages, 2333 KiB  
Article
Assessment of the Energy Security of EU Countries in Light of the Expansion of Renewable Energy Sources
by Aleksandra Kuzior, Yevhen Kovalenko, Inna Tiutiunyk and Larysa Hrytsenko
Energies 2025, 18(8), 2126; https://doi.org/10.3390/en18082126 - 21 Apr 2025
Abstract
In response to disturbances in the European energy market due to Russia’s invasion of Ukraine, Europe had to strengthen its strategic resilience and reduce reliance on Russian gas imports by conserving energy, producing clean energy, and diversifying energy sources. A crucial aspect of [...] Read more.
In response to disturbances in the European energy market due to Russia’s invasion of Ukraine, Europe had to strengthen its strategic resilience and reduce reliance on Russian gas imports by conserving energy, producing clean energy, and diversifying energy sources. A crucial aspect of this effort is assessing energy security, which serves as an indicator summarizing various aspects of energy development. This study evaluates the energy system’s ability to continuously, economically, and environmentally safely meet consumer needs in 28 European economies. This research employs non-linear (piecewise linear) normalization and the multiplicative convolution method, analyzing data from 2000 to 2021. Critical components of energy security examined include the resource supply, resource availability, consumption, compensability, efficiency, safety, and innovativeness. The findings indicate that most EU countries have sufficient-to-moderate levels of energy security. The histogram depicting the distribution of the energy security index and its components reveals that the innovation aspect within a country’s energy security framework has the lowest scores. This indicates insufficient innovation activity in developing and implementing new technologies and modern energy transportation and consumption methods. Consequently, the study highlights the inadequate effectiveness of current energy transition measures and offers recommendations for European policymakers based on these findings. Full article
(This article belongs to the Section B: Energy and Environment)
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19 pages, 888 KiB  
Review
Utility Theory Application in Decision-Making Behavior for Energy Use and Management: A Systematic Review
by Huiying (Cynthia) Hou
Energies 2025, 18(8), 2125; https://doi.org/10.3390/en18082125 - 21 Apr 2025
Abstract
This paper investigates the application of utility theory in decision-making related to energy use behavior and management practice in the energy sector. By conducting a systematic literature review, this study aims to understand the theoretical and practical applications of utility theory in optimizing [...] Read more.
This paper investigates the application of utility theory in decision-making related to energy use behavior and management practice in the energy sector. By conducting a systematic literature review, this study aims to understand the theoretical and practical applications of utility theory in optimizing energy consumption and management strategies. The review targets a comprehensive collection of academic works that apply utility theory to various aspects of energy use behavior and management decisions, including efficiency initiatives, renewable energy adoption, and sustainable infrastructure development. A systematic literature review methodology was adopted, which encompassed a rigorous selection process to identify relevant studies, followed by a detailed analysis of how utility theory has been employed to influence energy-related decisions in residential, commercial, and industrial settings. The review findings were synthesized to outline the implications for both policy and practice, highlighting the role of utility theory in guiding more efficient and sustainable energy management practices. Through this exploration, the paper provides a discussion on bridging the gap between economic theoretical models and practical energy management applications. It also offers insights into how decision-making influenced by utility theory can lead to enhanced energy efficiency and sustainability. The findings offer valuable guidance for policymakers and energy managers in designing and implementing energy systems and policies that maximize utility while considering environmental and economic impacts. This paper serves to advance the theoretical framework of utility theory and its practical application in energy management, facilitating better-informed strategies that align with global sustainability goals. Full article
(This article belongs to the Section B: Energy and Environment)
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15 pages, 11902 KiB  
Article
Comparative Analysis of Energy Efficiency in High-Voltage Ozone Generators: Resonant Versus Non-Resonant Systems
by Tongpian Prombud, Ekkapol Anusurain, Chainarong Wisassakwichai and Choosak Kamonkhantithorn
Energies 2025, 18(8), 2124; https://doi.org/10.3390/en18082124 - 21 Apr 2025
Abstract
The effective generation of ozone by high-voltage systems is essential for several industrial and environmental purposes. This paper performs a thorough comparative examination of energy efficiency in ozone generators, emphasizing resonant and non-resonant systems. Resonant ozone generators, which utilize tuned electrical circuits for [...] Read more.
The effective generation of ozone by high-voltage systems is essential for several industrial and environmental purposes. This paper performs a thorough comparative examination of energy efficiency in ozone generators, emphasizing resonant and non-resonant systems. Resonant ozone generators, which utilize tuned electrical circuits for optimal efficiency, are assessed in comparison to non-resonant systems that function without frequency tuning. The comparison analysis includes measures like energy use, ozone generation, and overall system efficiency. Experimental results demonstrate considerable differences in energy consumption between the two generator types, with resonant systems exhibiting substantially more efficiency in the conversion of electrical power into ozone. The resonant systems, producing 120 g/kWh, demonstrate 50% greater efficiency than the non-resonant systems, which generate 80 g/kWh, in terms of ozone production per unit of energy. This study clarifies the operational features, benefits, and drawbacks of each system, offering essential insights for the advancement of ozone-generating technologies in diverse applications. Full article
(This article belongs to the Special Issue Insulation Challenges in High-Voltage Transformers: Overcoming Barriers)
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18 pages, 3805 KiB  
Article
Design of Hybrid Cooling System for Thermal Management of Lithium-Ion Batteries Using Immersion Method with Nanofluid Supported Heat Pipes
by Osman Mert and Mehmet Özalp
Energies 2025, 18(8), 2123; https://doi.org/10.3390/en18082123 - 21 Apr 2025
Abstract
In this study, straight and looped heat pipes were designed and manufactured, and their performance in cooling cylindrical lithium-ion batteries known as standard 18,650 batteries on the market was investigated. Pure water, methanol, and thermasolv IM2 liquid were used as working fluids in [...] Read more.
In this study, straight and looped heat pipes were designed and manufactured, and their performance in cooling cylindrical lithium-ion batteries known as standard 18,650 batteries on the market was investigated. Pure water, methanol, and thermasolv IM2 liquid were used as working fluids in heat pipes. Nanofluid solutions were measured and prepared on a precision balance as 2% by weight according to the working fluid. These nanosolutions were injected into the heat pipes at a ratio of one-third by volume of the working fluids. In the designed experimental setup, the coils were placed 1 cm above the evaporator part of the heat pipes. Thanks to the designed electrical circuits, the amount of load given to and withdrawn from the batteries is controlled. The heated batteries evaporate the liquid in the heat pipe, the vapor rises and reaches the condenser. As a result of the evaporation, efficient heat transfer from the evaporator to the condenser takes place by transporting nanoparticles. At a certain flow rate, the refrigerant is transferred to the refrigerant as a result of the withdrawal of the refrigerant from the heat pipe. In this study, it is seen that the immersion method of the evaporator part in the pool full of IM2 liquid is repeated and the results are examined. Full article
(This article belongs to the Section J1: Heat and Mass Transfer)
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24 pages, 6059 KiB  
Review
Research Progress of Thermoelectric Materials—A Review
by Jun Wang, Yonggao Yin, Chunwen Che and Mengying Cui
Energies 2025, 18(8), 2122; https://doi.org/10.3390/en18082122 - 21 Apr 2025
Abstract
Thermoelectric materials are functional materials that directly convert thermal energy into electrical energy or vice versa, and due to their inherent properties, they hold significant potential in the field of energy conversion. In this review, we examine several fundamental strategies aimed at enhancing [...] Read more.
Thermoelectric materials are functional materials that directly convert thermal energy into electrical energy or vice versa, and due to their inherent properties, they hold significant potential in the field of energy conversion. In this review, we examine several fundamental strategies aimed at enhancing the conversion efficiency, classification, preparation methods, and applications of thermoelectric materials. First, we introduce an important parameter for evaluating the performance of thermoelectric materials, the dimensionless quality factor ZT, and present the theory of electroacoustic transport in thermoelectric materials, which provides the foundation for enhancing the performance of thermoelectric materials. Second, strategies for optimizing electroacoustic transport properties, carrier concentration, energy band engineering, phonon engineering, and entropy engineering are summarized, emphasizing that energy band engineering presents numerous possibilities for enhancing thermoelectric material performance by tuning the carrier effective mass, energy band convergence, and energy band resonance. By analyzing the importance of various optimization strategies, it is concluded that co-optimization is the primary method for improving the performance of thermoelectric materials in the future. In addition, an overview of the currently available thermoelectric materials is provided, including two categories, classical thermoelectric materials and novel thermoelectric materials, along with a highlight of two thermoelectric material preparation techniques. Finally, the principles of thermoelectric technology are illustrated, its applications in various fields are discussed, problems in the current research are analyzed, and future trends are outlined. Overall, this paper provides a comprehensive summary of optimization strategies, material classifications, and applications, offering valuable references and insights for the researchers in this field, with the aim of further advancing the development of thermoelectric material science. Full article
(This article belongs to the Section D1: Advanced Energy Materials)
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17 pages, 4081 KiB  
Article
Accuracy Performance of Open-Core Inductive Voltage Transformers at Higher Frequencies
by Josip Ivankić, Igor Žiger, Bruno Jurišić and Dubravko Franković
Energies 2025, 18(8), 2121; https://doi.org/10.3390/en18082121 - 20 Apr 2025
Abstract
The new revision of the main instrument transformer standard, IEC 61869-1:2023, premiered requirements for the performance of instrument transformers in terms of transfer accuracy at higher frequencies. Five accuracy class extensions were introduced to establish an explicit performance level. Each of the extension [...] Read more.
The new revision of the main instrument transformer standard, IEC 61869-1:2023, premiered requirements for the performance of instrument transformers in terms of transfer accuracy at higher frequencies. Five accuracy class extensions were introduced to establish an explicit performance level. Each of the extension levels has a distinct bandwidth and accuracy performance associated with it. While these requirements are mainly aimed at non-conventional instrument transformers, the hypothesis of this paper is that conventional high-voltage instrument transformers can have a performance conformant to the above-mentioned requirements. Specifically, the focus of this paper will be on open-core inductive voltage transformers, which inherently exhibit an improved frequency response in comparison to their conventional closed-core counterparts. The main aim of this paper is to present a relevant transformer model based on a lumped parameter equivalent diagram. This model considers the actual mutual coupling (both capacitive and inductive) of the transformer windings. The model is created in EMTP software, and the output yields a frequency response characteristic of the transformer. The model will be validated with test results obtained through measurements on actual 123 kV, 245 kV, and 420 kV inductive voltage transformers. Full article
(This article belongs to the Special Issue Energy, Electrical and Power Engineering: 3rd Edition)
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33 pages, 5789 KiB  
Review
Concentrated Solar Thermal Power Technology and Its Thermal Applications
by Chunchao Wu, Yonghong Zhao, Wulin Li, Jianjun Fan, Haixiang Xu, Zhongqian Ling, Dingkun Yuan and Xianyang Zeng
Energies 2025, 18(8), 2120; https://doi.org/10.3390/en18082120 - 20 Apr 2025
Abstract
The industrial sector accounts for approximately 65% of global energy consumption, with projections indicating a steady annual increase of 1.2% in energy demand. In the context of growing concerns about climate change and the need for sustainable energy solutions, solar thermal energy has [...] Read more.
The industrial sector accounts for approximately 65% of global energy consumption, with projections indicating a steady annual increase of 1.2% in energy demand. In the context of growing concerns about climate change and the need for sustainable energy solutions, solar thermal energy has emerged as a promising technology for reducing reliance on fossil fuels. With its ability to provide high-efficiency heat for industrial processes at temperatures ranging from 150 °C to over 500 °C, solar thermal power generation offers significant potential for decarbonizing energy-intensive industries. This review provides a comprehensive analysis of various solar thermal technologies, including parabolic troughs, solar towers, and linear Fresnel reflectors, comparing their effectiveness across different industrial applications such as process heating, desalination, and combined heat and power (CHP) systems. For instance, parabolic trough systems have demonstrated optimal performance in high-temperature applications, achieving efficiency levels up to 80% for steam generation, while solar towers are particularly suitable for large-scale, high-temperature operations, reaching temperatures above 1000 °C. The paper also evaluates the economic feasibility of these technologies, showing that solar thermal systems can achieve a levelized cost of energy (LCOE) of USD 60–100 per MWh, making them competitive with conventional energy sources in many regions. However, challenges such as high initial investment, intermittency of solar resource, and integration into existing industrial infrastructure remain significant barriers. This review not only discusses the technical principles and economic aspects of solar thermal power generation but also outlines specific recommendations for enhancing the scalability and industrial applicability of these technologies in the near future. Full article
(This article belongs to the Special Issue Renewable Energy Power Generation and Power Demand Side Management)
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30 pages, 10034 KiB  
Article
Study on Cold Start of Methanol Direct Injection Engine Based on Laser Ignition
by Xiaoyu Liu, Jie Zhu and Zhongcheng Wang
Energies 2025, 18(8), 2119; https://doi.org/10.3390/en18082119 - 20 Apr 2025
Abstract
Methanol has garnered attention as a promising alternative fuel for marine engines due to its high octane number and superior knock resistance. However, methanol-fueled engines face cold-start challenges under low-temperature conditions. Laser ignition technology, an emerging ignition approach, shows potential to replace conventional [...] Read more.
Methanol has garnered attention as a promising alternative fuel for marine engines due to its high octane number and superior knock resistance. However, methanol-fueled engines face cold-start challenges under low-temperature conditions. Laser ignition technology, an emerging ignition approach, shows potential to replace conventional spark ignition systems. This study investigates the effects of laser ignition on combustion and emission characteristics of direct-injection methanol engines based on methanol fuel combustion mechanisms using the AVL-Fire simulation platform, focusing on optimizing key parameters, including ignition energy, longitudinal depth, and lateral position, to provide theoretical support for efficient and clean combustion in marine medium-speed methanol engines. Key findings include an ignition energy threshold (60 mJ) for methanol combustion stability, with combustion parameters (peak pressure, heat release rate) stabilizing when energy reaches ≥80 mJ, recommending 80 mJ as the optimal energy level (balancing ignition reliability and energy consumption economy). Laser longitudinal depth significantly influences flame propagation characteristics, showing a 23% increase in flame propagation speed at 15 mm depth and a reduction of unburned methanol mass fraction to 0.8% at the end of combustion. Full article
(This article belongs to the Special Issue Advanced Combustion Technologies and Emission Control)
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6 pages, 149 KiB  
Editorial
Enabling Strategies and Policies Toward a Sustainable Environment
by Abdul Majeed and Judit Oláh
Energies 2025, 18(8), 2118; https://doi.org/10.3390/en18082118 - 20 Apr 2025
Abstract
This Topic, Enabling Strategies and Policies toward a Sustainable Environment, addresses the gaps in the literature by synthesizing pioneering research on the mechanisms driving sustainable transitions [...] Full article
(This article belongs to the Topic Enabling Strategies and Policies toward a Sustainable Environment)
64 pages, 5254 KiB  
Review
Mechanisms and Modelling of Effects on the Degradation Processes of a Proton Exchange Membrane (PEM) Fuel Cell: A Comprehensive Review
by Krystof Foniok, Lubomira Drozdova, Lukas Prokop, Filip Krupa, Pavel Kedron and Vojtech Blazek
Energies 2025, 18(8), 2117; https://doi.org/10.3390/en18082117 - 20 Apr 2025
Abstract
Proton Exchange Membrane Fuel Cells (PEMFCs), recognised for their high efficiency and zero emissions, represent a promising solution for automotive applications. Despite their potential, durability challenges under real-world automotive operating conditions—arising from chemical, mechanical, catalytic, and thermal degradation processes intensified by contaminants—limit their [...] Read more.
Proton Exchange Membrane Fuel Cells (PEMFCs), recognised for their high efficiency and zero emissions, represent a promising solution for automotive applications. Despite their potential, durability challenges under real-world automotive operating conditions—arising from chemical, mechanical, catalytic, and thermal degradation processes intensified by contaminants—limit their broader adoption. This review aims to systematically assess recent advancements in understanding and modelling PEMFC degradation mechanisms. The article critically evaluates experimental approaches integrated with advanced physicochemical modelling techniques, such as impedance spectroscopy, microstructural analysis, and hybrid modelling approaches, highlighting their strengths and specific limitations. Experimental studies conducted under dynamic, realistic conditions provide precise data for validating these models. The review explicitly compares physics-based, data-driven, and hybrid modelling strategies, discussing trade-offs between accuracy, computational demand, and generalizability. Key findings emphasise that hybrid models effectively balance precision with computational efficiency. Finally, the article identifies apparent research gaps. It suggests future directions, including developing degradation-resistant materials, improved simulation methodologies, and intelligent control systems to optimise PEMFC performance and enhance operational lifespan. Full article
(This article belongs to the Special Issue Advances in Hydrogen Energy IV)
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42 pages, 3689 KiB  
Article
Gossip Coordination Mechanism for Decentralised Learning
by Philippe Glass and Giovanna Di Marzo Serugendo
Energies 2025, 18(8), 2116; https://doi.org/10.3390/en18082116 - 20 Apr 2025
Abstract
In smart grids, renewable energies play a predominant role, but they produce more and more data, which are volatile by nature. As a result, predicting electrical behaviours has become a real challenge and requires solutions that involve more all microgrid entities in learning [...] Read more.
In smart grids, renewable energies play a predominant role, but they produce more and more data, which are volatile by nature. As a result, predicting electrical behaviours has become a real challenge and requires solutions that involve more all microgrid entities in learning processes. This research proposes the design of a coordination model that integrates two decentralised approaches to distributed learning applied to a microgrid: the gossip federated learning approach, which consists of exchanging learning models between neighbouring nodes, and the gossip ensemble learning approach, which consists of exchanging prediction results between neighbouring nodes. The experimentations, based on real data collected in a living laboratory, show that the combination of a coordination model and intelligent digital twins makes it possible to implement and operate these two purely decentralised learning approaches. The results obtained on the predictions confirm that these two implemented approaches can improve the efficiency of learning on the scale of a microgrid, while reducing the congestion caused by data exchanges. In addition, the generic gossip mechanism offers the flexibility to easily define different variants of an aggregation operator, which can help to maximise the performance obtained. Full article
(This article belongs to the Section F5: Artificial Intelligence and Smart Energy)
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14 pages, 2576 KiB  
Article
Optimization of Injection Strategy for CH4/Diesel Dual-Fuel Engine Using Response Surface Methodology
by Sarah Ouchikh, Mohand Said Lounici, Khaled Loubar and Mohand Tazerout
Energies 2025, 18(8), 2115; https://doi.org/10.3390/en18082115 - 20 Apr 2025
Viewed by 34
Abstract
Dual-fuel combustion technology allows for lower emissions of particulate matter (PM) and nitrogen oxide (NOx). However, under low load conditions, this mode of combustion has large amounts of emissions of carbon monoxide (CO) and unburned hydrocarbons (HCs) and low thermal efficiency. Several solutions [...] Read more.
Dual-fuel combustion technology allows for lower emissions of particulate matter (PM) and nitrogen oxide (NOx). However, under low load conditions, this mode of combustion has large amounts of emissions of carbon monoxide (CO) and unburned hydrocarbons (HCs) and low thermal efficiency. Several solutions have been presented to solve the issues associated with this operating mode. Optimizing the injection strategy is a potential method to enhance engine performance and reduce emissions, given that the injection parameters have significant effects on the combustion process. The present investigation optimized a methane/diesel dual-fuel engine’s emissions and performance using response surface methodology (RSM). Three parameters were investigated as input variables: dwell time (DT), diesel pre-injection timing (IT), and engine load (EL). RSM was used to optimize brake thermal efficiency (BTE), NOx emissions, and HC emissions, aiming to identify the best combination of these input factors. The RSM analysis revealed that the optimal combination of input parameters for achieving maximum BTE and minimum NOx and HC emissions is an 87% engine load, an 8° crank angle (CA) dwell time, and a 11° bTDC pre-injection timing. The RSM model demonstrated high accuracy with a prediction error less than 4%. Full article
(This article belongs to the Section A: Sustainable Energy)
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16 pages, 17097 KiB  
Article
Mechanical Metamaterials in Mitigating Vibrations in Battery Pack Casings
by Hsiao Mun Lee and Heow Pueh Lee
Energies 2025, 18(8), 2114; https://doi.org/10.3390/en18082114 - 19 Apr 2025
Viewed by 90
Abstract
Battery pack casings with a total energy of 12.432 kWh were designed using two types of materials: aluminum alloy and carbon fiber reinforced composite filament based on polyphthalamide or high-performance/high-temperature nylon (PPA-CF). The effectiveness of mechanical metamaterials (lattice and auxetic structures) in mitigating [...] Read more.
Battery pack casings with a total energy of 12.432 kWh were designed using two types of materials: aluminum alloy and carbon fiber reinforced composite filament based on polyphthalamide or high-performance/high-temperature nylon (PPA-CF). The effectiveness of mechanical metamaterials (lattice and auxetic structures) in mitigating the levels of random vibrations in the battery pack casings was studied using a numerical method. Both structures demonstrate outstanding capabilities with a 97% to 99% reduction in vibration levels in the aluminum casing. However, the capabilities of these structures in mitigating vibration levels in the PPA-CF casing are very limited, in that they can only mitigate approximately 63.8% and 92.8% of the longitudinal vibrations at the top cover of the casing and center of its front and back walls, respectively. Compared to PPA-CF, aluminum alloy shows better vibration mitigation performance with or without structural modification. Full article
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