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Volume 18
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Energies, Volume 18, Issue 1 (January-1 2025) – 222 articles

Cover Story (view full-size image): The integration of perovskite with silicon in tandem solar cells (TSCs) presents a promising approach in photovoltaic technology. The hybrid sequential deposition method, combining thermal evaporation and spin-coating, is key for fabricating perovskite films in textured TSCs. However, the difficulty of organic salt diffusion occurs due to the dense perovskite coverage layer (CPCL) formed by high-crystallinity precursors. This study investigates polar solvents as additives to n-butanol to enhance permeability through the CPCL. We show that dimethyl sulfoxide facilitates diffusion of organic salts, promoting transformation into uniform perovskite crystals. The resulting films exhibit improved quality, achieving a maximum power conversion efficiency of 29.12%. This method provides a robust pathway for high-quality perovskite films on industrial-grade textured silicon substrates. View this paper
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21 pages, 4389 KiB  
Article
Numerical Evaluation on Massif Vibration of Pumped Storage Power Plant in Hydraulic Transients
by Tao Wang, Hongfen Tang, Hongsheng Chen, Dong Ma, Yuchuan Wang and Honggang Fan
Energies 2025, 18(1), 222; https://doi.org/10.3390/en18010222 - 6 Jan 2025
Viewed by 618
Abstract
This research aims to assess the massif vibration that results from hydraulic transitions of pumped storage power plant (PSPP) and probe into their consequences on mountain stability. Firstly, numerical simulations of the hydraulic transitions in a pumped storage power plant were carried out, [...] Read more.
This research aims to assess the massif vibration that results from hydraulic transitions of pumped storage power plant (PSPP) and probe into their consequences on mountain stability. Firstly, numerical simulations of the hydraulic transitions in a pumped storage power plant were carried out, and the pressure pulsations within different sections of the waterway system under pumping and generating conditions were obtained. The historical pressure during the hydraulic transients was used as the dynamic loading condition for transient structural analysis. The time-history curves of horizontal and vertical accelerations were obtained for four main working conditions, and four detection areas were demarcated on the massif surface for analysis. The results showed that the maximum amplitude of horizontal acceleration occurred within the height range of 760 m to 960 m of work condition T2. Statistical methods and one-third octave analysis were further applied to analyze the acceleration time-history curves, showing that the highest vibration levels in the horizontal direction were observed at a specific frequency of 50 Hz. This study indicates that the hydraulic transition process of pumped-storage power stations will have a significant impact on massif stability; therefore, it is crucial to consider corresponding seismic mitigation measures during the design and operating stages to ensure structural safety. Full article
(This article belongs to the Section B: Energy and Environment)
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22 pages, 5950 KiB  
Article
Clustering Analysis for Active and Reactive Energy Consumption Data Based on AMI Measurements
by Oscar A. Bustos-Brinez and Javier Rosero Garcia
Energies 2025, 18(1), 221; https://doi.org/10.3390/en18010221 - 6 Jan 2025
Viewed by 441
Abstract
Electrical data analysis based on smart grids has become a fundamental tool used by electrical grid stakeholders to understand the energy consumption patterns of users, although many proposals in this area do not consider reactive energy as another source of useful information regarding [...] Read more.
Electrical data analysis based on smart grids has become a fundamental tool used by electrical grid stakeholders to understand the energy consumption patterns of users, although many proposals in this area do not consider reactive energy as another source of useful information regarding distribution costs and threats to the grid. In this regard, the analysis of reactive energy patterns can become an extremely useful addition to existing electrical data analysis frameworks. This work shows the application of a series of clustering techniques over measurements of both active and reactive energy consumption measured for end users from the Colombian electrical network, including an analysis of the efficiency of the network measured by calculating the ratio of active energy to total consumption (power factor) per user. This allows a detailed characterization of users to be compiled, based on the identification of different active and reactive energy consumption behaviors, which could help grid operators to improve overall grid management and to increase the efficiency of their reactive energy compensation strategies. Full article
(This article belongs to the Special Issue Computational Intelligence in Electrical Systems: 2nd Edition)
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32 pages, 10088 KiB  
Article
Fast Simulation of the Flow Field in a VAWT Wind Farm Using the Numerical Data Obtained by CFD Analysis for a Single Rotor
by Yutaka Hara, Md. Shameem Moral, Aoi Ide and Yoshifumi Jodai
Energies 2025, 18(1), 220; https://doi.org/10.3390/en18010220 - 6 Jan 2025
Viewed by 523
Abstract
The effects of an increase in output power owing to the close arrangement of vertical-axis wind turbines (VAWTs) are well known. With the ultimate goal of determining the optimal layout of a wind farm (WF) for VAWTs, this study proposes a new method [...] Read more.
The effects of an increase in output power owing to the close arrangement of vertical-axis wind turbines (VAWTs) are well known. With the ultimate goal of determining the optimal layout of a wind farm (WF) for VAWTs, this study proposes a new method for quickly calculating the flow field and power output of a virtual WF consisting of two-dimensional (2-D) miniature VAWT rotors. This new method constructs a flow field in a WF by superposing 2-D velocity numerical data around an isolated single VAWT obtained through a computational fluid dynamics (CFD) analysis. In the calculation process, the VAWTs were gradually increased one by one from the upstream side, and a calculation subroutine, in which the virtual upstream wind speed at each VAWT position was recalculated with the effects of other VAWTs, was repeated three times for each arrangement with a temporal number of VAWTs. This method includes the effects of the velocity gradient, secondary flow, and wake shift as models of turbine-to-turbine interaction. To verify the accuracy of the method, the VAWT rotor power outputs predicted by the proposed method for several types of rotor pairs, four-rotor tandem, and parallel arrangements were compared with the results of previous CFD analyses. This method was applied to four virtual WFs consisting of 16 miniature VAWTs. It was found that a layout consisting of two linear arrays of eight closely spaced VAWTs with wide spacing between the arrays yielded a significantly higher output than the other three layouts. The high-performance layout had fewer rotors in the wakes of the other rotors, and the induced flow speeds generated by the closely spaced VAWTs probably mutually enhanced their output power. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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15 pages, 5574 KiB  
Article
The Effect of Contaminants and Temperatures of a High-Palm-Oil Biodiesel Blend on the Lifetime of a Diesel Fuel Filter
by Ihwan Haryono, Muchammad Taufiq Suryantoro, Ade Kurniawan, Muhammad Ma’ruf, Budi Rochmanto, Hari Setiapraja, Ahmad Taufiqur Rohman, Respatya Teguh Soewono, Taufik Yuwono and Ahmad Syihan Auzani
Energies 2025, 18(1), 219; https://doi.org/10.3390/en18010219 - 6 Jan 2025
Viewed by 494
Abstract
The use of a high concentration of biodiesel blends has been implemented nationally in Indonesia as part of the government’s program to increase energy security and improve environmental quality. However, a high concentration of biodiesel, specifically a blending volume of 30% (B30), leads [...] Read more.
The use of a high concentration of biodiesel blends has been implemented nationally in Indonesia as part of the government’s program to increase energy security and improve environmental quality. However, a high concentration of biodiesel, specifically a blending volume of 30% (B30), leads to a shorter fuel filter lifetime compared with pure diesel fuel (B0), due to the precipitation of impurities from biodiesel and the presence of contaminants from the environment. A study was conducted involving a rig test to evaluate the effect of using B30 on filter lifetime, referred to as JIS D1617:1998. The results showed that the temperature and cleanliness of the biodiesel had a strong influence on filter blocking. B30 with an ISO cleanliness of 22/21/17 without added standard dust contaminants at 15 °C for 48 h produced larger amounts of deposits compared to B0 with an ISO cleanliness of 16/13/7 with the addition of 1 g of contaminant for the same treatment. B30 with 1 g of additional contaminants soaked at 15 °C produced a larger amount of deposit than B30 with 2 g of added contaminant soaked at ~27 °C. The weighing of the used filters showed that deposits that originated from biodiesel impurities and precipitations were the dominant material causing a reduced fuel filter lifetime. In addition to the cleanliness factor, a decrease in the micron rating of the filter resulted in a shorter filter lifetime. Full article
(This article belongs to the Section A4: Bio-Energy)
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18 pages, 8668 KiB  
Article
Research on Opening Reignition Characteristics and Suppression Measures of 750 kV AC Filter Circuit Breakers
by Jianguo Zhang, Pengcheng Sha, Feiyue Ma, Bo Niu, Xu Cai, Hui Ni and Junbo Deng
Energies 2025, 18(1), 218; https://doi.org/10.3390/en18010218 - 6 Jan 2025
Viewed by 424
Abstract
The operation of converter valves in converter stations often results in high reactive power consumption and harmonic generation, necessitating measures to maintain reactive power balance and ensure power quality. To achieve this, the filter bank circuit breaker is frequently switched on and off [...] Read more.
The operation of converter valves in converter stations often results in high reactive power consumption and harmonic generation, necessitating measures to maintain reactive power balance and ensure power quality. To achieve this, the filter bank circuit breaker is frequently switched on and off during daily operation. In recent years, multiple incidents of circuit breaker breakdown during the opening process have been reported. In this study, power systems computer-aided design (PSCAD)/electromagnetic transients including DC (EMTDC) V5.0 electromagnetic transient simulation software is used to simulate and calculate the overvoltage and inrush current under different configurations of circuit breaker operating mechanism dispersion, opening phase angle, and operating speed. Additionally, the suppression effects of two measures are compared: “phase selection opening” and “phase selection opening combined with controlled opening speed” to mitigate overvoltage and inrush current. The results demonstrate that for BP11/13 filters, HP24/36 filters, and HP3 filters, the combined strategy of “phase-selective opening with controlled opening speed” is more effective in suppressing inrush current and overvoltage. However, for SC filters, the suppression effect of this combined strategy is not significant. Considering economic and practical factors, it is more reasonable to adopt the phase-selective opening measure for SC filters. These findings provide guidance for ensuring the safe operation of AC filter circuit breakers. Full article
(This article belongs to the Section F6: High Voltage)
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21 pages, 23995 KiB  
Article
A Hybrid Dual-Axis Solar Tracking System: Combining Light-Sensing and Time-Based GPS for Optimal Energy Efficiency
by Muhammad Hammas, Hassen Fituri, Ali Shour, Ashraf Ali Khan, Usman Ali Khan and Shehab Ahmed
Energies 2025, 18(1), 217; https://doi.org/10.3390/en18010217 - 6 Jan 2025
Viewed by 662
Abstract
Fixed solar panels face significant energy loss as they cannot consistently capture optimal sunlight. Because of that, the overall efficiency of the PV panel will be reduced, and the installation requires larger land space to generate appropriate power; this stems from the use [...] Read more.
Fixed solar panels face significant energy loss as they cannot consistently capture optimal sunlight. Because of that, the overall efficiency of the PV panel will be reduced, and the installation requires larger land space to generate appropriate power; this stems from the use of a dual-axis solar tracking system, which can significantly increase overall energy production. The system is based on the combination of two approaches to precisely track the sunlight: first, using multiple LDRs (light-dependent resistors) as photo sensors to track the position of the sun by balancing the resistivity using a proportional integral deprival (PID) controller, and the second approach using the time-based control for cloudy days when sunlight is diffused, getting the time GPS coordinates and time to calculate the accurate position of the sun by determining the azimuth and altitude angle. This dual system significantly improves energy production by 33.23% compared to fixed systems and eliminates errors during shaded conditions while reducing unnecessary energy use from continuous GPS activation. The prototype uses two linear actuators for both angles and a 100-watt solar panel mounted on the dual-axis platform. Full article
(This article belongs to the Special Issue Power Quality and Hosting Capacity in the Microgrids)
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26 pages, 17602 KiB  
Article
Machine Learning-Based Prediction of 2 MW Wind Turbine Tower Loads During Power Production Based on Nacelle Behavior
by Soichiro Kiyoki, Shigeo Yoshida and Mostafa A. Rushdi
Energies 2025, 18(1), 216; https://doi.org/10.3390/en18010216 - 6 Jan 2025
Viewed by 636
Abstract
The cost of a wind turbine support structure is high and this support structure is difficult to repair, especially for offshore wind turbines. As such, the loads and stresses that occur during the actual operation of wind turbines must be monitored from the [...] Read more.
The cost of a wind turbine support structure is high and this support structure is difficult to repair, especially for offshore wind turbines. As such, the loads and stresses that occur during the actual operation of wind turbines must be monitored from the perspective of maintenance planning and lifetime prediction. Strain measurement methods are generally used to monitor the load on a structure and are highly accurate, but their widespread implementation across all wind turbines is impractical due to cost and labor constraints. In this study, a method for predicting the tower load was developed, using simple measurements applied during power generation, for onshore wind turbines. The method consists of a machine learning model, using the nacelle displacement and nacelle angle as inputs, which are highly correlated with loads at the bottom of the tower. Nacelle displacements can be derived from accelerations, which are already monitored in regard to most wind turbines; the nacelle angle can be calculated from the nacelle angle velocity, measured with a gyroscope. The low-frequency components that cannot be captured with these parameters were predicted using the operational condition data used for wind turbine control. Additionally, the prediction accuracy was increased by creating and integrating separate machine learning models for each typical vibration component. The method was evaluated through the aeroelastic simulation of a 2 MW wind turbine. The results showed that the fatigue and extreme loads of the fore–aft and side–side bending moments at the bottom of the tower can be predicted using operational conditions and nacelle accelerations, and the prediction accuracy in regard to the high-frequency components can be increased by adding the nacelle angle velocity into the model. Furthermore, the fatigue loads of the torsional torque can be evaluated using the nacelle angle velocity. The proposed method has the ability to predict the loads at the bottom of the tower without any, or with only a few, additional sensors. Full article
(This article belongs to the Special Issue Recent Developments of Wind Energy)
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16 pages, 9676 KiB  
Article
Analysis of Falling Block Characteristics in Salt Caverns Energy Storage Space
by Shengwei Dong, Taian Fang, Jifang Wan, Shan Wang, Yanqi Zhao, Xiaowen Chen, Xiaofeng Yang and Yangqing Sun
Energies 2025, 18(1), 215; https://doi.org/10.3390/en18010215 - 6 Jan 2025
Viewed by 503
Abstract
In the current global energy sector where energy storage technology is highly regarded, the development of storage technology is crucial. Utilizing specific underground space for the storage of oil and gas and other energy sources is the direction of future development, and the [...] Read more.
In the current global energy sector where energy storage technology is highly regarded, the development of storage technology is crucial. Utilizing specific underground space for the storage of oil and gas and other energy sources is the direction of future development, and the space formed by deep-salt-mine water dissolution extraction has gradually become the preferred choice. However, in actual operation, multi-layer salt cavities are prone to collapse of interlayer and bending of pipes, seriously affecting the progress, quality, and safety of the entire energy storage space construction. Therefore, based on relevant principles, a targeted experimental platform was established, by taking photos and measurements of the falling process of specific falling objects, simulating the situation of falling objects in actual energy storage spaces and their impact on related components. In-depth research was conducted on the probability of falling objects hitting the inner pipe and the horizontal impact force under different conditions, and the experimental results were verified by rigorous numerical simulation analysis. The research results show that falling objects impacts can cause related components to bend, with the maximum impact probability reaching 5.1% and the maximum horizontal impact force reaching 24.6 N. In addition, the hydraulic fluctuations caused by the suction and drainage of the cavity pipe column have a relatively small impact on the falling object trajectory. The research findings can provide practical and effective guidance for the safe construction of specific energy storage facilities, ensuring that construction can be carried out safely and efficiently, and contribute to the steady development of the energy storage industry as a whole. Full article
(This article belongs to the Special Issue The Technology of Oil and Gas Production with Low Energy Consumption)
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20 pages, 14170 KiB  
Article
Three-Direction Type of Diffuser-Shaped Vortex Generator Development for the Wind Solar Tower
by Anan Sudsanguan, Amnart Boonloi and Withada Jedsadaratanachai
Energies 2025, 18(1), 214; https://doi.org/10.3390/en18010214 - 6 Jan 2025
Viewed by 443
Abstract
This study explored the use of diffuser shapes to enhance the performance of a solar updraft tower. A diffuser-shaped vortex generator, a simple device requiring no structural modifications to the tower, was installed at the chimney outlet. The generator transformed crosswind into a [...] Read more.
This study explored the use of diffuser shapes to enhance the performance of a solar updraft tower. A diffuser-shaped vortex generator, a simple device requiring no structural modifications to the tower, was installed at the chimney outlet. The generator transformed crosswind into a vortex, increasing the updraft velocity. This study employed finite element methods and numerical models to validate the results alongside physical experiments. Both approaches focused on the crosswind velocity and vortex generator height to determine an optimal semi-opening angle for the diffuser shape. The experimental results revealed that an 8° diffuser-shaped vortex generator with a height of hvg = 2D achieved the greatest updraft enhancement, increasing the speed by 86.89% compared to the prototype tower. The enhancement was found to increase proportionally with the generator’s angle and height. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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17 pages, 1703 KiB  
Article
Refined Assessment Method of Offshore Wind Resources Based on Interpolation Method
by Wenchuan Meng, Zaimin Yang, Zhi Rao, Shuang Li, Xin Lin, Jingkang Peng, Yuwei Cao and Yingquan Chen
Energies 2025, 18(1), 213; https://doi.org/10.3390/en18010213 - 6 Jan 2025
Viewed by 387
Abstract
To enhance the prediction accuracy of offshore wind speed, this study employs an interpolation algorithm to improve spatial resolution based on the ERA5 reanalysis dataset. The objective is to identify the optimal interpolation method and apply it to wind energy assessments in the [...] Read more.
To enhance the prediction accuracy of offshore wind speed, this study employs an interpolation algorithm to improve spatial resolution based on the ERA5 reanalysis dataset. The objective is to identify the optimal interpolation method and apply it to wind energy assessments in the South China Sea. This paper compares the interpolation effects and accuracy of Linear, Cubic, and Bicubic interpolation methods on wind speed data, with the optimal method subsequently applied to evaluate wind resources in the South China Sea for 2023. The findings indicate that, while different interpolation methods minimally affect the correlation of wind speed data, there are notable differences in their impact on overall accuracy. The Cubic interpolation method proved to be the most effective, tripling spatial resolution and reducing wind speed errors in ERA5 data by 26%. Using this method, wind resource assessments were conducted in selected areas of the South China Sea. Results reveal that the annual available operational hours for wind turbines in most parts of the region range from 2000 to 4000 h, with fluctuations in turbine output power increasing alongside available operational hours. Full article
(This article belongs to the Special Issue Recent Developments in Offshore Renewable Energies: Wind, Wave, Tidal, and Ocean Energy)
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14 pages, 4767 KiB  
Article
Experimental Assessment of Magnetic Nanofluid Injection in High-Salinity and Heavy-Crude-Saturated Sandstone: Mitigation of Formation Damage
by Jimena Lizeth Gómez-Delgado, Nelson Gutierrez-Niño, Luis Felipe Carrillo-Moreno, Raúl Andres Martínez-López, Nicolás Santos-Santos and Enrique Mejía-Ospino
Energies 2025, 18(1), 212; https://doi.org/10.3390/en18010212 - 6 Jan 2025
Viewed by 464
Abstract
The depletion of conventional oil reserves has intensified the search for enhanced oil recovery (EOR) techniques. Recently, nanoparticle research has focused on graphene oxide-based materials, revealing a critical challenge in their practical application. Laboratory investigations have consistently demonstrated that these nanoparticles have significant [...] Read more.
The depletion of conventional oil reserves has intensified the search for enhanced oil recovery (EOR) techniques. Recently, nanoparticle research has focused on graphene oxide-based materials, revealing a critical challenge in their practical application. Laboratory investigations have consistently demonstrated that these nanoparticles have significant potential for formation damage, a critical limitation that substantially constrains their potential field implementation. This research addresses a critical challenge in EOR: developing magnetic graphene oxide nanoparticles (MGONs) that can traverse rock formations without causing formation damage. MGONs were synthesized and stabilized in formation brine with a high total dissolved solids (TDS) content with a xanthan gum polymer. Two coreflooding experiments were conducted on sandstone cores. The first experiment on high-permeability sandstone (843 mD) showed no formation damage; instead, permeability increased to 935 mD after MGON injection. Irreducible water saturation (Swirr) and residual oil saturation (Sor) were 25.1% and 31.5%, respectively. The second experiment on lower-permeability rock (231.3 mD) evaluated nanoparticle retention. The results showed that 0.09511 mg of MGONs was adsorbed per gram of rock under dynamic conditions. Iron concentration in effluents stabilized after 3 pore volumes, indicating steady-state adsorption. The successful synthesis, stability in high-TDS brine, favorable interfacial properties, and positive effects observed in coreflooding experiments collectively highlight MGONs’ potential as a viable solution for enhancing oil recovery in challenging reservoirs, without causing formation damage. Full article
(This article belongs to the Special Issue Failure and Multiphysical Fields in Geo-Energy)
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21 pages, 13816 KiB  
Article
Robust Wireless Power Transfer for EVs by Self-Oscillating Controlled Inverters and Identical Single-Coil Transmitting and Receiving Pads
by Alireza Eikani, Mohammad Amirkhani, Ehsan Farmahini Farahani, Volker Pickert, Mojtaba Mirsalim and Sadegh Vaez-Zadeh
Energies 2025, 18(1), 211; https://doi.org/10.3390/en18010211 - 6 Jan 2025
Viewed by 573
Abstract
Inductive wireless power transfer (IWPT) with stable output power and high efficiency is a major challenge for charging electric vehicles (EVs). This paper, for the first time, develops a robust IWPT system using a circular pad (CP) and double-D pad (DDP) with a [...] Read more.
Inductive wireless power transfer (IWPT) with stable output power and high efficiency is a major challenge for charging electric vehicles (EVs). This paper, for the first time, develops a robust IWPT system using a circular pad (CP) and double-D pad (DDP) with a self-oscillating controlled inverter (SOCI), which offers high steady output power and transfer efficiency under magnetic coupling variations simply with feedback from the transmitter-side current. The compact 2CP and 2DDP magnetic couplers with single identical coils are robust to self- and mutual-inductance variations, so the IWPT system exhibits greater robustness at increased transfer distances (air gaps), as well as in the presence of lateral and rotational misalignments between the two magnetic pads, compared to couplers using nonidentical transmitting primary (TP) and receiving secondary (RS) pads and numerous decoupled coils on the RS pad. Based on a thorough analysis and experimental study, the proposed 1 kW IWPT system with 2CP and 2DDP couplers with up to a 20 cm air gap achieves constant output power with 93% and 92% constant transfer efficiency, respectively. The 2CP with a 15 cm air gap and the 2DDP with a 20 cm air gap, with up to 12 cm lateral misalignment, can tolerate coupling variations. Full article
(This article belongs to the Special Issue Recent Advances in Power Electronics and Wireless Power Transfer Systems)
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22 pages, 13540 KiB  
Article
Petroleum System Analysis and Migration Pathways in the Late Paleozoic Source Rock Strata and Sandstone Reservoirs in the Ordos Basin
by Qingfeng Guan and Jingong Zhang
Energies 2025, 18(1), 210; https://doi.org/10.3390/en18010210 - 6 Jan 2025
Viewed by 423
Abstract
The migration system, as the primary medium linking source rocks and traps, plays a vital role in studying hydrocarbon migration, accumulation, and reservoir formation. This study focuses on Late Paleozoic source rock (mudstone and coal rock) and sandstone samples from the Ordos Basin. [...] Read more.
The migration system, as the primary medium linking source rocks and traps, plays a vital role in studying hydrocarbon migration, accumulation, and reservoir formation. This study focuses on Late Paleozoic source rock (mudstone and coal rock) and sandstone samples from the Ordos Basin. By analyzing permeability, porosity, and their ratios under various conditions, this study evaluates the quality of hydrocarbon migration pathways across different lithologic strata, identifies optimal migration routes, and offers new insights for identifying favorable hydrocarbon exploration areas in the Late Paleozoic of the Ordos Basin. The findings indicate that the permeability ratio between parallel and vertical bedding planes in source rock and sandstone samples ranges from 1 to 4. Post-fracturing, permeability increases by over twofold. On average, sandstone permeability is approximately 0.1 × 10⁻3 μm2, while source rock permeability is about 0.03 × 10⁻3 μm2. Key conclusions include that without fracture development, permeability, and porosity parallel to bedding planes outperform those perpendicular to bedding planes, with sandstone showing better properties than source rocks. When fractures are present, permeability and porosity along the fracture direction are highest, followed by sandstone, with source rocks showing the lowest values. These results advance the theoretical understanding of hydrocarbon migration systems and provide significant guidance for hydrocarbon reservoir exploration and development. Full article
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34 pages, 5571 KiB  
Review
New Advances in Bioelectrochemical Systems in the Degradation of Polycyclic Aromatic Hydrocarbons: Source, Degradation Pathway, and Microbial Community
by Yimeng Feng, Xuya Zhu, Xiulin Huang and Fengxiang Li
Energies 2025, 18(1), 209; https://doi.org/10.3390/en18010209 - 6 Jan 2025
Viewed by 612
Abstract
Because of their high persistence, polycyclic aromatic hydrocarbons (PAHs) are found in a wide range of settings and pose a health risk to both humans and other organisms. Degradation of PAHs is an essential part of environmental management. By combining biological metabolism and [...] Read more.
Because of their high persistence, polycyclic aromatic hydrocarbons (PAHs) are found in a wide range of settings and pose a health risk to both humans and other organisms. Degradation of PAHs is an essential part of environmental management. By combining biological metabolism and electrochemical processes, bioelectrochemical systems (BESs) can degrade PAHs and provide important applications by converting the chemical energy of pollutants into electrical energy for energy conversion and recovery. This review provides a comprehensive introduction to PAH degradation by BESs, including PAH sources, degradation effects of BESs, performance enhancement methods, degradation pathways, and dominant microorganisms. By focusing on the relevant research in recent years, the main innovative research focuses on the optimization of the configuration, the electrode preparation, and the media additions to improve the removal performance of PAHs. It demonstrates the potential of BESs in the field of environmental remediation, especially their effectiveness in treating difficult-to-degrade pollutants such as PAHs, by concentrating on the application and mechanism of BESs in PAH degradation. This review is intended to provide the inexperienced reader with an insight into this research area and to point out directions for future research, especially in the design optimization of BESs and microbial community analysis. Full article
(This article belongs to the Section B: Energy and Environment)
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23 pages, 6432 KiB  
Article
Simulation of PEM Electrolyzer Power Management with Renewable Generation in Owerri, Nigeria
by MacMatthew C. Ahaotu, Chisom E. Ogbogu, Jesse Thornburg and Isdore Onyema Akwukwaegbu
Energies 2025, 18(1), 208; https://doi.org/10.3390/en18010208 - 6 Jan 2025
Viewed by 604
Abstract
Proton exchange membrane electrolyzers are an attractive technology for hydrogen production due to their high efficiency, low maintenance cost, and scalability. To receive these benefits, however, electrolyzers require high power reliability and have relatively high demand. Due to their intermittent nature, integrating renewable [...] Read more.
Proton exchange membrane electrolyzers are an attractive technology for hydrogen production due to their high efficiency, low maintenance cost, and scalability. To receive these benefits, however, electrolyzers require high power reliability and have relatively high demand. Due to their intermittent nature, integrating renewable energy sources like solar and wind has traditionally resulted in a supply too sporadic to consistently power a proton exchange membrane electrolyzer. This study develops an electrolyzer model operating with renewable energy sources at a highly instrumented university site. The simulation uses dynamic models of photovoltaic solar and wind systems to develop models capable of responding to changing climatic and seasonal conditions. The aim therefore is to observe the feasibility of operating a proton exchange membrane system fuel cell year-round at optimal efficiency. To address the problem of feasibility with dynamic renewable generation, a case study demonstrates the proposed energy management system. A site with a river onsite is chosen to ensure sufficient wind resources. Aside from assessing the feasibility of pairing renewable generation with proton exchange membrane systems, this project shows a reduction in the intermittency plaguing previous designs. Finally, the study quantifies the performance and effectiveness of the PEM energy management system design. Overall, this study highlights the potential of proton exchange membrane electrolysis as a critical technology for sustainable hydrogen production and the importance of modeling and simulation techniques in achieving its full potential. Full article
(This article belongs to the Special Issue Low-Carbon Integrated Energy System with Renewable Generations: Characterization, Modelling, and Optimization)
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15 pages, 4219 KiB  
Article
Geometry Optimisation of a Wave Energy Converter
by Susana Costa, Jorge Ferreira and Nelson Martins
Energies 2025, 18(1), 207; https://doi.org/10.3390/en18010207 - 6 Jan 2025
Viewed by 483
Abstract
The geometry optimisation of a point-absorber wave energy converter, focusing on the increase in energy absorption derived from heave forces, was performed. The proposed procedure starts by developing an initial geometry, which is later evaluated in terms of hydrodynamics and optimised through an [...] Read more.
The geometry optimisation of a point-absorber wave energy converter, focusing on the increase in energy absorption derived from heave forces, was performed. The proposed procedure starts by developing an initial geometry, which is later evaluated in terms of hydrodynamics and optimised through an optimisation algorithm to tune the shape parameters that influence energy absorption, intending to obtain the optimal geometry. A deployment site on the Portuguese coast was defined to obtain information on the predominant waves to assess several sea states. NEMOH and WEC-Sim (both open-source software packages) were used to evaluate the interaction between the structure and the imposed wave conditions. The results extracted and analysed from this software included forces in the six degrees of freedom. Under extreme wave conditions, the highest increase in the relative capture width between the initial and final shapes was around 0.2, corresponding to an increase from 0.36 to 0.54, while under average wave conditions, the increase only reached a value of around 0.02, corresponding to an increase from 0.22 to 0.24, as calculated through the relative capture width values. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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15 pages, 9693 KiB  
Article
Distribution Characteristics of Swirling-Straight Sprinklers Inside a Nuclear Power Pressurizer
by Jinghao Bi and Xiao Xu
Energies 2025, 18(1), 206; https://doi.org/10.3390/en18010206 - 6 Jan 2025
Viewed by 447
Abstract
Droplet size and distribution uniformity of sprinklers significantly affect production safety in the processes of steam temperature and pressure reduction within nuclear power, and other high-temperature, high-pressure industries. In industrial sprays with high flow rates and low pressure drops, reducing droplet size poses [...] Read more.
Droplet size and distribution uniformity of sprinklers significantly affect production safety in the processes of steam temperature and pressure reduction within nuclear power, and other high-temperature, high-pressure industries. In industrial sprays with high flow rates and low pressure drops, reducing droplet size poses additional challenges, making improved spray uniformity essential for enhancing heat transfer. This study designed and produced a set of swirling-straight sprinklers, tested their flow characteristics and liquid distribution, and proposed a highly uniform spray mode involving swirl jet interaction mixing. The discharge coefficient (Cd) changes indicated that enlarging the jet channel area diminishes the amplification effect, suggesting a trade-off in industrial high flow sprinkler design. A detailed evaluation and analysis method of the spray process, which is superior to the use of a single uniformity parameter, is proposed based on Gaussian function peak fitting method. It has been observed that the relationship between the Gaussian fitting parameters and the pressure drop of the sprinkler tends to be linear. This discovery provides a new basis for designing nozzles with low pressure drop, high flow rates, and uniform distribution. The findings contribute to the optimization of spray performance and provide valuable data for computational fluid dynamics model verification. Full article
(This article belongs to the Special Issue Advanced Technologies in Nuclear Engineering)
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22 pages, 5604 KiB  
Article
Solar Energy Forecasting Framework Using Prophet Based Machine Learning Model: An Opportunity to Explore Solar Energy Potential in Muscat Oman
by Mazhar Baloch, Mohamed Shaik Honnurvali, Adnan Kabbani, Touqeer Ahmed, Sohaib Tahir Chauhdary and Muhammad Salman Saeed
Energies 2025, 18(1), 205; https://doi.org/10.3390/en18010205 - 6 Jan 2025
Viewed by 716
Abstract
The unpredictable nature of renewable energy sources, such as wind and solar, makes them unreliable sources of energy for the power system. Nevertheless, with the advancement in the field of artificial intelligence (AI), one can predict the availability of solar and wind energy [...] Read more.
The unpredictable nature of renewable energy sources, such as wind and solar, makes them unreliable sources of energy for the power system. Nevertheless, with the advancement in the field of artificial intelligence (AI), one can predict the availability of solar and wind energy in the short, medium, and long term with fairly high accuracy. As such, this research work aims to develop a machine-learning-based framework for forecasting global horizontal irradiance (GHI) for Muscat, Oman. The proposed framework includes a data preprocessing stage, where the missing entries in the acquired data are imputed using the mean value imputation method. Afterward, data scaling is carried out to avoid the overfitting/underfitting of the model. Features such as the GHI cloudy sky index, the GHI clear sky index, global normal irradiance (GNI) for a cloudy sky, GNI for a clear sky, direct normal irradiance (DNI) for a cloudy sky, and DNI for a clear sky are extracted. After analyzing the correlation between the abovementioned features, model training and the testing procedure are initiated. In this research, different models, named Linear Regression (LR), Support Vector Machine (SVR), KNN Regressor, Decision Forest Regressor, XGBoost Regressor, Neural Network (NN), Autoregressive Integrated Moving Average (ARIMA), Long Short-Term Memory (LSTM), Random Forest Regressor, Categorical Boosting (CatBoost), Deep Autoregressive (DeepAR), and Facebook Prophet, are trained and tested under both identical features and a training–testing ratio. The model evaluation metrics used in this study include the mean absolute error (MAE), the root mean squared error (RMSE), R2, and mean bias deviation (MBD). Based on the outcomes of this study, it is concluded that the Facebook Prophet model outperforms all of the other utilized conventional machine learning models, with MAE, RMSE, and R2 values of 9.876, 18.762, and 0.991 for the cloudy conditions and 11.613, 19.951 and 0.988 for the clean weather conditions, respectively. The mentioned error values are the lowest among all of the studied models, which makes Facebook Prophet the most accurate solar irradiance forecasting model for Muscat, Oman. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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16 pages, 11088 KiB  
Article
Thermal Performance Analysis of Nanofluids for Heat Dissipation Based on Fluent
by Junqiang Xu, Zemin Shang and Shan Qing
Energies 2025, 18(1), 204; https://doi.org/10.3390/en18010204 - 6 Jan 2025
Viewed by 540
Abstract
With the increasing demand for thermal management in electronic devices and industrial systems, nanofluids have emerged as a research hotspot due to their superior thermal conductivity and heat transfer efficiency. Among them, CuO-H2O demonstrates excellent heat transfer performance due to its [...] Read more.
With the increasing demand for thermal management in electronic devices and industrial systems, nanofluids have emerged as a research hotspot due to their superior thermal conductivity and heat transfer efficiency. Among them, CuO-H2O demonstrates excellent heat transfer performance due to its high thermal conductivity, Fe3O4-H2O offers potential for further optimization by combining thermal and magnetic properties, and Al2O3-H2O exhibits strong chemical stability, making it suitable for a wide range of applications. These three nanofluids are representative in terms of particle dispersibility, thermal conductivity, and physical properties, providing a comprehensive perspective on the impact of nanofluids on microchannel heat exchangers. This study investigates the heat transfer performance and flow characteristics of various types and volume fractions of nanofluids in microchannel heat exchangers. The results reveal that with increasing flow rates, the convective heat transfer coefficient and Nusselt number of nanofluids exhibit an approximately linear growth trend, primarily attributed to the turbulence enhancement effect caused by higher flow rates. Among the tested nanofluids, CuO-H2O demonstrates the best performance, achieving a 4.89% improvement in the heat transfer coefficient and a 1.64% increase in the Nusselt number compared to pure water. Moreover, CuO-H2O nanofluid significantly reduces wall temperatures, showcasing its superior thermal management capabilities. In comparison, the performance of Al2O3-H2O and Fe3O4-H2O nanofluids is slightly inferior. In terms of flow characteristics, the pressure drop and friction factor of nanofluids exhibit nonlinear variations with increasing flow rates. High-concentration CuO-H2O nanofluid shows a substantial pressure drop, with an increase of 7.33% compared to pure water, but its friction factor remains relatively low and stabilizes at higher flow rates. Additionally, increasing the nanoparticle volume fraction enhances the convective heat transfer performance; however, excessively high concentrations may suppress heat transfer efficiency due to increased viscosity, leading to a decrease in the Nusselt number. Overall, CuO-H2O nanofluid exhibits excellent thermal conductivity and flow optimization potential, making it a promising candidate for efficient thermal management in MCHEs. However, its application at high concentrations may face challenges related to increased flow resistance. These findings provide valuable theoretical support and optimization directions for the development of advanced thermal management technologies. Full article
(This article belongs to the Section J: Thermal Management)
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27 pages, 15823 KiB  
Article
Multi-Objective Optimization of the Energy, Exergy, and Environmental Performance of a Hybrid Solar–Biomass Combined Brayton/Organic Rankine Cycle
by Guillermo Valencia-Ochoa, Jorge Duarte-Forero and Daniel Mendoza-Casseres
Energies 2025, 18(1), 203; https://doi.org/10.3390/en18010203 - 6 Jan 2025
Viewed by 691
Abstract
This research proposes integrating a combined system from a supercritical Brayton cycle (SBC) at extremely high temperatures and pressures and a conventional ORC cycle. The ORC cycle was evaluated with three working fluids: acetone, toluene, and cyclohexane. Of these, the cyclohexane, thanks to [...] Read more.
This research proposes integrating a combined system from a supercritical Brayton cycle (SBC) at extremely high temperatures and pressures and a conventional ORC cycle. The ORC cycle was evaluated with three working fluids: acetone, toluene, and cyclohexane. Of these, the cyclohexane, thanks to its dry fluid condition, obtained the best result in the sensitivity analysis for the energetic and exergetic evaluations with the most relevant (net power and exergy destruction) for the variation in the most critical performance parameter of the system for both the configuration with reheat and the configuration with recompression. Between the two proposed configurations, the most favorable performance was obtained with a binary system with reheat and recompression; with reheat, the SBC obtained first- and second-law efficiencies of 45.8% and 25.2%, respectively, while the SBC obtained values of 54.8% and 27.9%, respectively, with reheat and recompression. Thus, an increase in overall system efficiency of 30.3% is obtained. In addition, the destroyed exergy is reduced by 23% due to the bypass before the evaporation process. The SBC-ORC combined hybrid system with reheat and recompression has a solar radiation of 950 W/m2 K, an exhaust heat recovery efficiency of 0.85, and a turbine inlet temperature of 1008.15 K. The high pressure is 25,000 kPa, the isentropic efficiency of the turbines is 0.8, the pressure ratio is 12, and the pinch point of the evaporator is initially 20 °C and reaches values of 45 °C in favorable supercritical conditions. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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12 pages, 3346 KiB  
Article
A Digital Twin of Hot Pumping Waxy Oil Through a Main Pipeline
by Uzak Zhapbasbayev, Timur Bekibayev, Gaukhar Ramazanova and Zhibek Akasheva
Energies 2025, 18(1), 202; https://doi.org/10.3390/en18010202 - 5 Jan 2025
Viewed by 704
Abstract
This article presents a digital twin of hot pumping waxy oil through a main pipeline. Digital copies of the original object data were identified through sensor measurements from SCADA and ECMAS, forming the basis of the SmartTranPro 1.7.1 Software. The mathematical model of [...] Read more.
This article presents a digital twin of hot pumping waxy oil through a main pipeline. Digital copies of the original object data were identified through sensor measurements from SCADA and ECMAS, forming the basis of the SmartTranPro 1.7.1 Software. The mathematical model of the software describes the process of hot pumping waxy oil regarding heat exchange with the environment. The intelligent algorithms of the SmartTranPro 1.7.1 Software were used to determine the actual dependencies of the digital twins of the objects, hydraulic parameters, and heat transfer for the Kassymov–Bolshoi Chagan hot main pipeline, which has a length of 450 km. The results of the thermal–hydraulic calculations for the hot pumping of waxy oil are in good agreement with the actual sensor data from SCADA and ECASM. The optimization calculations of the heating temperature for waxy oil show an economic efficiency of 38.9% for the hot pumping method. Full article
(This article belongs to the Section H: Geo-Energy)
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24 pages, 6317 KiB  
Article
BIM-Based Machine Learning Application for Parametric Assessment of Building Energy Performance
by Panagiotis Tsikas, Athanasios Chassiakos, Vasileios Papadimitropoulos and Antonios Papamanolis
Energies 2025, 18(1), 201; https://doi.org/10.3390/en18010201 - 5 Jan 2025
Viewed by 953
Abstract
The energy performance of buildings has become a main concern globally in response to increased energy demand, the environmental impacts of energy production, and the reality of energy poverty. To improve energy efficiency, proper building design should be secured at the early design [...] Read more.
The energy performance of buildings has become a main concern globally in response to increased energy demand, the environmental impacts of energy production, and the reality of energy poverty. To improve energy efficiency, proper building design should be secured at the early design phase. Digital tools are currently available for performing energy assessment analyses and can efficiently handle complex and technically demanding buildings. However, alternative designs should be checked individually, and this makes the process time-consuming and prone to errors. Machine learning techniques can provide valuable assistance in developing decision support tools. In this paper, typical residential buildings are considered along with eleven factors that highly affect energy performance. A dataset of 337 instances of such parameters is developed. For each dataset, the building energy performance is estimated based on BIM analysis. Next, statistical and machine learning techniques are implemented to provide artificial models of energy performance. They include statistical regression modeling (SRM), decision trees (DTs), random forests (RFs), and artificial neural networks (ANNs). The analysis reveals the contribution of each factor and highlights the ANN as the best performing model. An easy-to-use interface tool has been developed for the instantaneous calculation of the energy performance based on the independent parameter values. Full article
(This article belongs to the Special Issue Building Energy Performance Modelling and Simulation)
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18 pages, 8536 KiB  
Article
Permeability Characteristics of Combined Coal with Different Water Contents
by Hongyu Pan, Yao Zhang, Lei Zhang, Yan Cao, Yuhang Chu and Shihua Yang
Energies 2025, 18(1), 200; https://doi.org/10.3390/en18010200 - 5 Jan 2025
Viewed by 586
Abstract
Hydraulic fracturing changes the stress state of the coal body, and the residual water within the coal body after fracturing affects its permeability characteristics. To examine the impact of hydraulic measures on the permeability of coal under varying water contents and radial stress [...] Read more.
Hydraulic fracturing changes the stress state of the coal body, and the residual water within the coal body after fracturing affects its permeability characteristics. To examine the impact of hydraulic measures on the permeability of coal under varying water contents and radial stress distributions, permeability tests were conducted using the improved LFTD1812 triaxial permeameter. The flow rate of coal under different water content combinations was measured, and the permeability, pressure gradient, and seepage velocity of the samples were calculated. The relationships among porosity, permeability, pressure gradient, and seepage velocity were analyzed. The effect of water content on permeability was evaluated, and the directional behavior of permeability was identified. The results showed that the porosity of the samples with water contents of 25%, 17.5%, and 10% decreased by 48.5%, 23.9%, and 17.6%, respectively, during the loading process. The permeability of all samples ranged from 1.91 × 10−13 m2 to 76.91 × 10−13 m2. As the absolute value of the pressure gradient increased, the downward trend of permeability was categorized into three stages: rapid, slow, and stable. Higher water content corresponded to lower initial permeability, with the permeability–pressure gradient curve shifting downward. Additionally, the slow decline zone moved to the right, and the absolute value of the pressure gradient required to enter this zone decreased. Seepage velocity consistently decreased with increasing water content across all osmotic pressure levels, although the rate of decline progressively weakened. The maximum permeability difference between the forward and reverse samples was 10.48 × 10−13 m2. Permeability directionality decreased with increasing equivalent water content and osmotic pressure, with water content identified as the primary influencing factor. Permeability variations caused by axial compression were divided into three phases: the weak influence of the polarization effect, the transition phase, and the strong influence phase. These findings confirm that water content has the most significant impact on permeability, demonstrating that gas flow primarily follows the principle of distance priority toward the nearest borehole. Boreholes closer to the source exhibit higher extraction volumes. These results provide theoretical support for improving coal permeability, enhancing gas drainage efficiency, and preventing gas accidents through hydraulic measures. Full article
(This article belongs to the Section H: Geo-Energy)
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26 pages, 27035 KiB  
Article
Enhancing Air Conditioning System Efficiency Through Load Prediction and Deep Reinforcement Learning: A Case Study of Ground Source Heat Pumps
by Zhitao Wang, Yubin Qiu, Shiyu Zhou, Yanfa Tian, Xiangyuan Zhu, Jiying Liu and Shengze Lu
Energies 2025, 18(1), 199; https://doi.org/10.3390/en18010199 - 5 Jan 2025
Viewed by 953
Abstract
This study proposes a control method that integrates deep reinforcement learning with load forecasting, to enhance the energy efficiency of ground source heat pump systems. Eight machine learning models are first developed to predict future cooling loads, and the optimal one is then [...] Read more.
This study proposes a control method that integrates deep reinforcement learning with load forecasting, to enhance the energy efficiency of ground source heat pump systems. Eight machine learning models are first developed to predict future cooling loads, and the optimal one is then incorporated into deep reinforcement learning. Through interaction with the environment, the optimal control strategy is identified using a deep Q-network to optimize the supply water temperature from the ground source, allowing for energy savings. The obtained results show that the XGBoost model significantly outperforms other models in terms of prediction accuracy, reaching a coefficient of determination of 0.982, a mean absolute percentage error of 6.621%, and a coefficient of variation for the root mean square error of 10.612%. Moreover, the energy savings achieved through the load forecasting-based deep reinforcement learning control method are greater than those of traditional constant water temperature control methods by 10%. Additionally, without shortening the control interval, the energy savings are improved by 0.38% compared with deep reinforcement learning control methods that do not use predictive information. This approach requires only continuous interaction and learning between the agent and the environment, which makes it an effective alternative in scenarios where sensor and equipment data are not present. It provides a smart and adaptive optimization control solution for heating, ventilation, and air conditioning systems in buildings. Full article
(This article belongs to the Section A: Sustainable Energy)
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21 pages, 7149 KiB  
Article
Experimental Testing Results on Critical Components for Molten Salt-Based CSP Systems
by Valeria Russo, Giuseppe Petroni, Francesco Rovense, Mauro Giorgetti, Giuseppe Napoli, Gianremo Giorgi and Walter Gaggioli
Energies 2025, 18(1), 198; https://doi.org/10.3390/en18010198 - 5 Jan 2025
Viewed by 628
Abstract
Concentrated Solar Power (CSP) plants integrated with Thermal Energy Storage (TES) represent a promising renewable energy source for generating heat and power. Binary molten salt mixtures, commonly referred to as Solar Salts, are utilized as effective heat transfer fluids and storage media due [...] Read more.
Concentrated Solar Power (CSP) plants integrated with Thermal Energy Storage (TES) represent a promising renewable energy source for generating heat and power. Binary molten salt mixtures, commonly referred to as Solar Salts, are utilized as effective heat transfer fluids and storage media due to their thermal stability and favorable thermophysical properties. However, these mixtures pose significant challenges due to their high solidification temperatures, around 240 °C, which can compromise the longevity and reliability of critical system components such as pressure sensors and bellows seal globe valves. Thus, it is essential to characterize their performance, assess their reliability under various conditions, and understand their failure mechanisms, particularly in relation to temperature fluctuations affecting the fluid’s viscosity. This article discusses experimental tests conducted on a pressure sensor and a bellows seal globe valve, both designed for direct contact with molten salts in CSP environments, at the ENEA Casaccia Research Center laboratory in Rome. The methodology for conducting these experimental tests is detailed, and guidelines are outlined to optimize plant operation. The findings provide essential insights for improving component design and maintenance to minimize unplanned plant downtime. They also offer methodologies for installing measurement instruments and electrical heating systems on the components. Full article
(This article belongs to the Special Issue Solar Thermal Heat and Power Technology: Developments and Applications)
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21 pages, 2201 KiB  
Article
Ultra-Short-Term Distributed Photovoltaic Power Probabilistic Forecasting Method Based on Federated Learning and Joint Probability Distribution Modeling
by Yubo Wang, Chao Huo, Fei Xu, Libin Zheng and Ling Hao
Energies 2025, 18(1), 197; https://doi.org/10.3390/en18010197 - 5 Jan 2025
Viewed by 583
Abstract
The accurate probabilistic forecasting of ultra-short-term power generation from distributed photovoltaic (DPV) systems is of great significance for optimizing electricity markets and managing energy on the user side. Existing methods regarding cluster information sharing tend to easily trigger issues of data privacy leakage [...] Read more.
The accurate probabilistic forecasting of ultra-short-term power generation from distributed photovoltaic (DPV) systems is of great significance for optimizing electricity markets and managing energy on the user side. Existing methods regarding cluster information sharing tend to easily trigger issues of data privacy leakage during information sharing, or they suffer from insufficient information sharing while protecting data privacy, leading to suboptimal forecasting performance. To address these issues, this paper proposes a privacy-preserving deep federated learning method for the probabilistic forecasting of ultra-short-term power generation from DPV systems. Firstly, a collaborative feature federated learning framework is established. For the central server, information sharing among clients is realized through the interaction of global models and features while avoiding the direct interaction of raw data to ensure the security of client data privacy. For local clients, a Transformer autoencoder is used as the forecasting model to extract local temporal features, which are combined with global features to form spatiotemporal correlation features, thereby deeply exploring the spatiotemporal correlations between different power stations and improving the accuracy of forecasting. Subsequently, a joint probability distribution model of forecasting values and errors is constructed, and the distribution patterns of errors are finely studied based on the dependencies between data to enhance the accuracy of probabilistic forecasting. Finally, the effectiveness of the proposed method was validated through real datasets. Full article
(This article belongs to the Special Issue Leveraging Flexibility Resources to Enhance Renewable Energy Integration and Grid Stability)
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27 pages, 6682 KiB  
Review
Renewable Energy for Sustainable Development: Opportunities and Current Landscape
by Dzintra Atstāja
Energies 2025, 18(1), 196; https://doi.org/10.3390/en18010196 - 5 Jan 2025
Viewed by 732
Abstract
Energy is often described as the lifeblood of a nation’s economy, and the world energy trilemma calls for collaboration and innovative solutions at the national level. This is where Education for Sustainable Development (ESD) plays a crucial role, helping integrate the achievement of [...] Read more.
Energy is often described as the lifeblood of a nation’s economy, and the world energy trilemma calls for collaboration and innovative solutions at the national level. This is where Education for Sustainable Development (ESD) plays a crucial role, helping integrate the achievement of the United Nations Sustainable Development Goals (SDGs) while addressing the challenges posed by the energy trilemma. Europe’s strong commitment to transitioning to sustainable energy is evident in its response to geopolitical changes and climate targets. Notably, the Baltic States have taken decisive action in response to the war in Ukraine, choosing to completely halt electricity imports from Russia and Belarus. This shift was supported by increased energy imports via interconnectors from Finland, Sweden, and Poland, with electricity imports rising to 13,053 GWh—an increase of 2.6% in 2023 compared to the previous year. Latvia, which holds the highest green energy potential in the Baltic Sea region, has nevertheless lagged behind its Baltic counterparts in terms of implementation. In 2021, Latvia ranked third among European Union (EU) countries for renewable energy share in final energy consumption, with 42.1%, significantly higher than the EU average of 21.8%. However, further progress is needed to meet Latvia’s 2030 target of 14% renewable energy use in transport. The Baltic States aim to produce 98–100% of their electricity from renewable sources by 2050. The Baltic States should be regarded as a unified energy system, with a coordinated strategy for achieving sustainable energy development through collaboration and joint planning. This analysis highlights the complexities of managing energy markets amidst global and regional challenges, emphasizing the importance of well-designed public interventions to secure long-term benefits. The study concludes with a call for enhanced interagency cooperation to reform ESD and create a new interdisciplinary sector dedicated to “Sustainable Development”. Full article
(This article belongs to the Collection Renewable Energy and Energy Storage Systems)
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20 pages, 9558 KiB  
Article
Enhancing Thermal Performance Investigations of a Methane-Fueled Planar Micro-Combustor with a Counter-Flow Flame Configuration
by Liaoliao Li, Yuze Sun, Xinyu Huang, Lixian Guo and Xinyu Zhao
Energies 2025, 18(1), 195; https://doi.org/10.3390/en18010195 - 5 Jan 2025
Viewed by 442
Abstract
To enhance the performance of combustors in micro thermophotovoltaic systems, this study employs numerical simulations to investigate a planar microscale combustor featuring a counter-flow flame configuration. The analysis begins with an evaluation of the effects of (1) equivalence ratio Φ and (2) inlet [...] Read more.
To enhance the performance of combustors in micro thermophotovoltaic systems, this study employs numerical simulations to investigate a planar microscale combustor featuring a counter-flow flame configuration. The analysis begins with an evaluation of the effects of (1) equivalence ratio Φ and (2) inlet flow rate Vi on key thermal and combustion parameters, including the average temperature of the combustor main wall (T¯w), wall temperature non-uniformity (R¯Tw) and radiation efficiency (ηr). The findings indicate that increasing Φ causes these parameters to initially increase and subsequently decrease. Similarly, increasing the inlet flow rate leads to a monotonic decline in ηr, while the T¯w and R¯Tw exhibit a rise-then-fall trend. A comparative study between the proposed combustor and a conventional planar combustor reveals that, under identical inlet flow rate and equivalence ratio conditions, the use of the counterflow flame configuration can increase the T¯w while reducing the R¯Tw. The Nusselt number analysis shows that the counter-flow flame configuration micro-combustor achieves a larger area with positive Nusselt numbers and higher average Nusselt numbers, which highlights improved heat transfer from the fluid to the solid. Furthermore, the comparison of blow-off limits shows that the combustor with counter-flow flame configuration exhibits superior flame stability and a broader flammability range. Overall, this study provides a preliminary investigation into the use of counter-flow flame configurations in microscale combustors. Full article
(This article belongs to the Special Issue Challenges and Research Trends of Exhaust Emissions)
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57 pages, 17482 KiB  
Review
Comprehensive Overview of the Effective Thermal Conductivity for Hydride Materials: Experimental and Modeling Approaches
by Gabriele Scarpati, Julián A. Puszkiel, Jan Warfsmann, Fahim Karimi, Elio Jannelli, Claudio Pistidda, Thomas Klassen and Julian Jepsen
Energies 2025, 18(1), 194; https://doi.org/10.3390/en18010194 - 5 Jan 2025
Viewed by 680
Abstract
In metal hydride beds (MHBs), reaction heat transfer often limits the dynamic performance. Heat transfer within the MHB usually involves solid and gas phases. To account for both, an effective thermal conductivity (ETC) is defined. Measuring and predicting the ETC of metal hydride [...] Read more.
In metal hydride beds (MHBs), reaction heat transfer often limits the dynamic performance. Heat transfer within the MHB usually involves solid and gas phases. To account for both, an effective thermal conductivity (ETC) is defined. Measuring and predicting the ETC of metal hydride beds is of primary importance when designing hydride-based systems for high dynamics. This review paper presents an integral overview of the experimental and modeling approaches to characterize the ETC in MHBs. The most relevant methods for measuring the ETC of metal hydride beds are described, and the results and scopes are shown. A comprehensive description of the models applied to calculate the ETC of the MHBs under different conditions is developed. Moreover, the effects of operation parameters such as P, T, and composition on the ETC of the presented models are analyzed. Finally, a summary and conclusions about experimental techniques, a historical overview with a classification of the ETC models, a discussion about the needed parameters, and a comparison between ETC experimental and calculated results are provided. Full article
(This article belongs to the Special Issue Research on Integration and Storage Technology of Hydrogen Energy)
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21 pages, 5790 KiB  
Article
Sealing Effects on Organic Pore Development in Marine Shale Gas: New Insights from Macro- to Micro-Scale Analyses
by Qiumei Zhou, Hao Xu, Wen Zhou, Xin Zhao, Ruiyin Liu and Ke Jiang
Energies 2025, 18(1), 193; https://doi.org/10.3390/en18010193 - 5 Jan 2025
Viewed by 456
Abstract
The physics of how organic pores change under high thermal evolution conditions in overmature marine shale gas formations remains unclear. In this study, systematic analyses at the macro- to micro-scales were performed to reveal the effects of the sealing capacity on organic pore [...] Read more.
The physics of how organic pores change under high thermal evolution conditions in overmature marine shale gas formations remains unclear. In this study, systematic analyses at the macro- to micro-scales were performed to reveal the effects of the sealing capacity on organic pore development. Pyrolysis experiments were conducted in semi-closed and open systems which provided solid evidence demonstrating the importance of the sealing capacity. Low-maturity marine shale samples from the Dalong Formation were used in the pyrolysis experiments, which were conducted at 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, and 600 °C. The pore characteristics and geochemical parameters of the samples were examined after each thermal simulation stage. The results showed that the TOC of the semi-closed system decreased gradually, while the TOC of the open system decreased sharply at 350 °C and exhibited almost no change thereafter. The maximum porosity, specific surface area, and pore volume of the semi-closed system (10.35%, 2.99 m2/g, and 0.0153 cm3/g) were larger than those of the open system (3.87%, 1.97 m2/g, and 0.0059 cm3/g). In addition, when the temperature was 600 °C, the pore diameter distribution in the open system was 0.001–0.1 μm, while the pore diameter distribution in the semi-closed system was 0.001–10 μm. The pore volumes of the macropores and mesopores in the semi-closed system remained larger than those in the open system. The pore volumes of the micropores in the semi-closed and open systems were similar. The pyrolysis results indicated that (1) the pressure difference caused by the sealing capacity controls organic pore development; (2) organic pores developed in the semi-closed system, and the differences between the two systems mainly occurred in the overmature stage; and (3) the differences were caused by changes in the macropore and mesopore volumes, not the micropore volume. It was concluded that the sealing capacity is the key factor for gas pore generation in the overmature stage of marine shale gas reservoirs when the organic matter (OM) type, volume, and thermal evolution degree are all similar. The macropores and mesopores are easily affected by the sealing conditions, but the micropores are not. Finally, the pyrolysis simulation results were validated with the Longmaxi shale and Qiongzhusi shale properties. The Longmaxi shale is similar to semi-closed system, and the Qiongzhusi shale is similar to open system. Two thermal evolution patterns of organic pore development were proposed based on the pyrolysis results. This study provides new insights into the evolution patterns of organic pores in marine shale gas reservoirs. Full article
(This article belongs to the Topic Formation Mechanism and Quantitative Evaluation of Deep to Ultra-Deep High-Quality Reservoirs)
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