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Volume 18
Issue 15
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Energies, Volume 18, Issue 15 (August-1 2025) – 319 articles

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18 pages, 2405 KiB  
Article
Dynamic Comparative Assessment of Long-Term Simulation Strategies for an Off-Grid PV–AEM Electrolyzer System
by Roberta Caponi, Domenico Vizza, Claudia Bassano, Luca Del Zotto and Enrico Bocci
Energies 2025, 18(15), 4209; https://doi.org/10.3390/en18154209 - 7 Aug 2025
Viewed by 440
Abstract
Among the various renewable-powered pathways for green hydrogen production, solar photovoltaic (PV) technology represents a particularly promising option due to its environmental sustainability, widespread availability, and declining costs. However, the inherent intermittency of solar irradiance presents operational challenges for electrolyzers, particularly in terms [...] Read more.
Among the various renewable-powered pathways for green hydrogen production, solar photovoltaic (PV) technology represents a particularly promising option due to its environmental sustainability, widespread availability, and declining costs. However, the inherent intermittency of solar irradiance presents operational challenges for electrolyzers, particularly in terms of stability and efficiency. This study presents a MATLAB-based dynamic model of an off-grid, DC-coupled solar PV-Anion Exchange Membrane (AEM) electrolyzer system, with a specific focus on realistically estimating hydrogen output. The model incorporates thermal energy management strategies, including electrolyte pre-heating during startup, and accounts for performance degradation due to load cycling. The model is designed for a comprehensive analysis of hydrogen production by employing a 10-year time series of irradiance and ambient temperature profiles as inputs. The results are compared with two simplified scenarios: one that does not consider the equipment response time to variable supply and another that assumes a fixed start temperature to evaluate their impact on productivity. Furthermore, to limit the effects of degradation, the algorithm has been modified to allow the non-sequential activation of the stacks, resulting in an improvement of the single stack efficiency over the lifetime and a slight increase in overall hydrogen production. Full article
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20 pages, 3203 KiB  
Article
Experiment Driven Co-Simulation Model of Wheel Loader Attachment Hydraulics System for Influence Assessment of Hydraulic Accumulator Parameters on Energy Recuperation Efficiency
by Cezary Rudzki, Adam Bartnicki, Arkadiusz Rubiec, Tomasz Muszyński and Mirosław Przybysz
Energies 2025, 18(15), 4208; https://doi.org/10.3390/en18154208 - 7 Aug 2025
Viewed by 220
Abstract
The following paper describes research on the influence of hydraulic accumulator parameters on the efficiency of energy recovery for a simulation model of a wheel loader using the results of experimental research. A design solution for the energy recovery system for the loader [...] Read more.
The following paper describes research on the influence of hydraulic accumulator parameters on the efficiency of energy recovery for a simulation model of a wheel loader using the results of experimental research. A design solution for the energy recovery system for the loader attachment was presented, which allows for the recovery of the potential energy of the boom, bucket, and load. The presented simulation model was developed based on a real object. The necessary operating parameters were determined using experimental tests. The study used the co-simulation method of mechanical and hydraulic models in order to more accurately reflect the actual behavior of the research object. The validated simulation model was extended with the developed energy recovery module based on a hydraulic accumulator. The results of the conducted tests have indicated the influence of hydraulic accumulator parameters on the efficiency of energy recovery and potential directions for further research. Full article
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22 pages, 4739 KiB  
Article
Leakage Testing of Gas Meters Designed for Measuring Hydrogen-Containing Gas Mixtures and Pure Hydrogen
by Zbigniew Gacek
Energies 2025, 18(15), 4207; https://doi.org/10.3390/en18154207 - 7 Aug 2025
Viewed by 164
Abstract
Green hydrogen is a clean, versatile, and future-oriented fuel that can play a key role in the energy transition, decarbonization of the economy, and climate protection. It offers an alternative to fossil fuels and can be used in various applications, including power generation, [...] Read more.
Green hydrogen is a clean, versatile, and future-oriented fuel that can play a key role in the energy transition, decarbonization of the economy, and climate protection. It offers an alternative to fossil fuels and can be used in various applications, including power generation, industry, and transportation. However, due to its wide flammability range, small molecular size, and high diffusivity, special attention must be paid to ensuring safety during its use, particularly in leakage control. This paper provides a review and analysis of equipment leakage testing methods used for natural gas, with a view to applying these methods to the leakage testing of gas meters intended for hydrogen-containing gas mixtures and pure hydrogen. Tests of simulated leaks were carried out using two common methods: the bubble method and the pressure decay method, for three different gases: nitrogen (most commonly used for leak testing), helium, and hydrogen. The results obtained from the tests and analyses made it possible to verify and select optimum leak-testing methods for gas meters designed for measuring fuels containing hydrogen. Full article
(This article belongs to the Section A5: Hydrogen Energy)
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14 pages, 3207 KiB  
Article
Grid-Tied PV Power Smoothing Using an Energy Storage System: Gaussian Tuning
by Ahmad I. Alyan, Nasrudin Abd Rahim and Jeyraj Selvaraj
Energies 2025, 18(15), 4206; https://doi.org/10.3390/en18154206 - 7 Aug 2025
Viewed by 198
Abstract
The use of power smoothing for renewable energy resources is attracting increasing attention. One widely used resource that could benefit from this technique is the grid-tied photovoltaic (PV) system. Solar energy production typically follows a Gaussian bell curve, with peaks at midday. This [...] Read more.
The use of power smoothing for renewable energy resources is attracting increasing attention. One widely used resource that could benefit from this technique is the grid-tied photovoltaic (PV) system. Solar energy production typically follows a Gaussian bell curve, with peaks at midday. This paper confirms this pattern by using the bell curve as a reference; however, climate variations can significantly alter this pattern. Therefore, this study aimed to smooth the power supplied to the grid by a PV system. The proposed controller manages the charge and discharge processes of the energy storage system (ESS) to ensure a smooth Gaussian bell curve output. It adjusts the parameters of this curve to closely match the generated energy, absorbing or supplying fluctuations to maintain the desired profile. This system also aims to provide accurate predictions of the power that should be supplied to the grid by the PV system, based on the capabilities of the ESS and the overall system performance. Although experimental results were not included in this analysis, the system was implemented in SIMULINK using real-world data. The controller utilizes a hybrid ESS comprising a vanadium redox battery (VRB) and supercapacitors (SCs). The design and operation of the controller, including curve tuning and ESS charge–discharge management, are detailed. The simulation results demonstrate excellent performance and are thoroughly discussed. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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18 pages, 11439 KiB  
Article
Machine Learning-Driven Prediction of CO2 Solubility in Brine: A Hybrid Grey Wolf Optimizer (GWO)-Assisted Gaussian Process Regression (GPR) Approach
by Seyed Hossein Hashemi, Farshid Torabi and Paitoon Tontiwachwuthikul
Energies 2025, 18(15), 4205; https://doi.org/10.3390/en18154205 - 7 Aug 2025
Viewed by 165
Abstract
The solubility of CO2 in brine systems is critical for both carbon storage and enhanced oil recovery (EOR) applications. In this study, Gaussian Process Regression (GPR) with eight different kernels was optimized using the Grey Wolf Optimizer (GWO) algorithm to model this [...] Read more.
The solubility of CO2 in brine systems is critical for both carbon storage and enhanced oil recovery (EOR) applications. In this study, Gaussian Process Regression (GPR) with eight different kernels was optimized using the Grey Wolf Optimizer (GWO) algorithm to model this important phase behavior. Among the tested kernels, the ARD Matern 3/2 and ARD Matern 5/2 kernels achieved the highest predictive accuracies, with R2 values of 0.9961 and 0.9960, respectively, on the test data. This demonstrates superior performance in capturing CO2 solubility trends. The GWO algorithm effectively tuned the hyperparameters for all kernel configurations, while the ARD capability successfully quantified the influence of key physicochemical parameters on CO2 solubility. The outstanding performance of the ARD Matern 3/2 and ARD Matern 5/2 kernels suggests their particular suitability for modeling complex thermodynamic behaviors in brine systems. Furthermore, this study integrates fundamental thermodynamic principles into the modeling framework, ensuring all predictions adhere to physical laws while maintaining excellent accuracy (test R2 > 0.98). These results highlight how machine learning can improve CO2 injection processes, both for underground carbon storage and enhanced oil production. Full article
(This article belongs to the Special Issue Advances in Carbon Dioxide (CO2) Enhanced Oil Recovery (EOR) and Carbon Capture and Storage (CCS))
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22 pages, 4651 KiB  
Review
Potential Issues and Optimization Solutions for High-Compression-Ratio Utilization in Hybrid-Dedicated Gasoline Engines
by Qiuyu Liu, Baitan Ma, Zhiqiang Zhang, Chunyun Fu and Zhe Kang
Energies 2025, 18(15), 4204; https://doi.org/10.3390/en18154204 - 7 Aug 2025
Viewed by 306
Abstract
This systematic review critically examines the benefits and challenges of high-compression-ratio (CR) implementation in hybrid-dedicated engines, recognizing CR increase as a pivotal strategy for enhancing the indicated thermal efficiency to achieve carbon peak and carbon neutrality goals. However, excessively high CRs face critical [...] Read more.
This systematic review critically examines the benefits and challenges of high-compression-ratio (CR) implementation in hybrid-dedicated engines, recognizing CR increase as a pivotal strategy for enhancing the indicated thermal efficiency to achieve carbon peak and carbon neutrality goals. However, excessively high CRs face critical constraints, including intensified knock propensity, increased heat transfer (HTR) losses, reduced combustion stability, augmented dissociation losses, and cold-start misfire risks. The feasibility and necessity of CR enhancement in hybrid systems were comprehensively evaluated based on these factors, with fundamental mechanisms of the detrimental effects elucidated. To address these challenges, optimized countermeasures were synthesized: knock suppression via high-octane fuels, EGR technology, lean combustion, and in-cylinder water injection; heat transfer reduction through thermal barrier coatings and independent CR/expansion-ratio control; misfire risk monitoring using ion current or cylinder pressure sensors. These approaches provide viable pathways to overcome high-CR limitations and optimize engine performance. Nevertheless, current research remains confined to isolated solutions, warranting future focus on integrated optimization mechanisms investigating synergistic interactions of multiple strategies under high-CR conditions. Full article
(This article belongs to the Special Issue Advances in Combustion Strategies and Fuels for Sustainable Energy and Propulsion)
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21 pages, 2090 KiB  
Article
The Dynamic Evolution of Industrial Electricity Consumption Linkages and Flow Path in China
by Jinshi Wei
Energies 2025, 18(15), 4203; https://doi.org/10.3390/en18154203 - 7 Aug 2025
Viewed by 224
Abstract
An in-depth investigation into the evolutionary characteristics, transmission mechanisms, and optimization pathways of electricity consumption linkages across China’s industrial sectors highlights their substantial theoretical and practical significance in achieving the “dual carbon” goals and advancing high-quality economic development. This study investigates the structural [...] Read more.
An in-depth investigation into the evolutionary characteristics, transmission mechanisms, and optimization pathways of electricity consumption linkages across China’s industrial sectors highlights their substantial theoretical and practical significance in achieving the “dual carbon” goals and advancing high-quality economic development. This study investigates the structural characteristics and developmental trends of electricity consumption linkages across China’s industrial sectors using an enhanced hypothetical extraction method. The analysis draws on national input–output tables and sector-specific electricity consumption data during the period from 2002 to 2020. Key transmission routes between industrial sectors are identified through path analysis and average path length calculations. The findings reveal that China’s industrial electricity consumption structure is marked by notable scale expansion and differentiation. The magnitude of inter-sectoral electricity flows continues to grow steadily. The evolution of these linkages exhibits clear phase-specific patterns, while the intensity of electricity consumption connections across sectors shows pronounced heterogeneity. Furthermore, the transmission path analysis revealed differentiated characteristics of electricity influence transmission, with generally shorter internal paths within sectors, significant cross-sectoral transmission differences, and manufacturing demonstrating good transmission accessibility with moderate path distances to major sectors. These insights provide a robust foundation for designing differentiated energy conservation policies, as well as for optimizing the overall structure of industrial electricity consumption. Full article
(This article belongs to the Special Issue Sustainable Energy Futures: Economic Policies and Market Trends)
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14 pages, 2727 KiB  
Article
Research on Power Transmission Capacity of Transmission Section for Grid-Forming Renewable Energy via AC/DC Parallel Transmission System Considering Synchronization and Frequency Stability Constraints
by Zhengnan Gao, Zengze Tu, Shaoyun Ding, Liqiang Wang, Haiyan Wu, Xiaoxiang Wei, Jiapeng Li and Yujun Li
Energies 2025, 18(15), 4202; https://doi.org/10.3390/en18154202 - 7 Aug 2025
Viewed by 224
Abstract
AC/DC parallel transmission is a critical approach for large-scale centralized transmission. Existing assessments of power transfer capability in AC/DC corridors rarely incorporate comprehensive security and stability constraints, potentially leading to overestimated results. This paper investigates a grid-forming renewable energy system integrated via AC/DC [...] Read more.
AC/DC parallel transmission is a critical approach for large-scale centralized transmission. Existing assessments of power transfer capability in AC/DC corridors rarely incorporate comprehensive security and stability constraints, potentially leading to overestimated results. This paper investigates a grid-forming renewable energy system integrated via AC/DC parallel transmission. First, the transmission section’s power transfer limit under N-1 static security constraints is determined. Subsequently, analytical conditions satisfying synchronization and frequency stability constraints are derived using the equal area criterion and frequency security indices, revealing the impacts of AC/DC power allocation and system parameters on transfer capability. Finally, by integrating static security, synchronization stability, and frequency stability constraints, an operational region for secure AC/DC power dispatch is established. Based on this region, an optimal power allocation scheme maximizing the corridor’s transfer capability is proposed. The theoretical framework and methodology enhance system transfer capacity while ensuring AC/DC parallel transmission security, with case studies validating the theory’s correctness and method’s effectiveness. Full article
(This article belongs to the Special Issue Safe and Stable Operation of Power-Electronics-Dominated Power Systems)
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19 pages, 3355 KiB  
Article
EU Energy Markets and Renewable Energy Sources—Are We Waiting for a Crisis?
by Tomasz Sieńko and Jerzy Szczepanik
Energies 2025, 18(15), 4201; https://doi.org/10.3390/en18154201 - 7 Aug 2025
Viewed by 207
Abstract
Interactions between the increased penetration of the power system by renewable energy sources (RESs) and the energy pricing mechanism in the EU (day-ahead market) can lead to many unexpected and paradoxical consequences. This article analyses the case of the long-term maintenance of prices [...] Read more.
Interactions between the increased penetration of the power system by renewable energy sources (RESs) and the energy pricing mechanism in the EU (day-ahead market) can lead to many unexpected and paradoxical consequences. This article analyses the case of the long-term maintenance of prices around zero on the day-ahead market in south-western Europe at a certain time of a day. This is an important case since, at the same time, this area generates electricity from a similar source mix as it is in the target for the EU. Zero or very low energy prices are becoming increasingly common across the EU. This can pose a problem for the stability of the electricity supply, as it translates into a lower power of used disposable power sources, which can be used as a reserve when the majority of the energy supply comes from renewable energy sources. Furthermore, this work refutes the most frequently proposed solution to the problem of excessively low prices based on energy storage systems. This work attempts to analyze the long-term low-price situation in Spain and extrapolate the expected consequences based on it; however, it is difficult to find all the factors that occur in the power system and influence the price market and vice versa. The issue is multidimensional and complex, and the analyzed situation revealed a number of trends. Therefore, a multifaceted problem remains. A constant electricity supply must be ensured at a reasonable price, thus avoiding the exposure of individual consumers to energy shortages or significant price increases, while, at the same time, the EU must reduce dependence on fossil fuels, and its legislation must push for reduced CO2 emissions. On the other hand, the EU must provide some type of market mechanism to support the achievement of these goals because the current pricing mechanism based on the day-ahead market does not seem to be effective. This article aims to spark a discussion about this problem; it does not provide any simple solutions to it. Full article
(This article belongs to the Special Issue Economic Analysis and Policies in the Energy Sector—2nd Edition)
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16 pages, 1414 KiB  
Review
Systems Thinking for Climate Change and Clean Energy
by Hassan Qudrat-Ullah
Energies 2025, 18(15), 4200; https://doi.org/10.3390/en18154200 - 7 Aug 2025
Viewed by 245
Abstract
Addressing climate change and advancing clean energy transitions demand holistic approaches that capture complex, interconnected system behaviors. This review focuses on the application of causal loop diagrams (CLDs) as a core systems-thinking methodology to understand and manage dynamic feedback within environmental, social, and [...] Read more.
Addressing climate change and advancing clean energy transitions demand holistic approaches that capture complex, interconnected system behaviors. This review focuses on the application of causal loop diagrams (CLDs) as a core systems-thinking methodology to understand and manage dynamic feedback within environmental, social, and technological domains. CLDs visually map the reinforcing and balancing loops that drive climate risks, clean energy adoption, and sustainable development, offering intuitive insights into system structure and behavior. Through a synthesis of empirical studies and case examples, this paper demonstrates how CLDs help identify leverage points in renewable energy policy, carbon management, and ecosystem resilience. Despite their strengths in simplifying complexity and enhancing stakeholder communication, challenges remain—including data gaps, model validation, and the integration of diverse knowledge systems. The review also examines recent innovations that improve CLD effectiveness, such as hybrid modeling approaches and digital tools that enhance transparency and decision support. By emphasizing CLDs’ unique capacity to reveal feedback mechanisms critical for climate action and energy planning, this study provides actionable recommendations for researchers, policymakers, and practitioners seeking to leverage systems thinking for transformative, sustainable solutions. Full article
(This article belongs to the Special Issue Clean and Efficient Use of Energy: 3rd Edition)
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22 pages, 6392 KiB  
Article
Comparison of Triple-Tube Heat Exchanger and Spherical Ice Balls for Energy Storage Performance: A Numerical Study
by Gülşah Karaca Dolgun
Energies 2025, 18(15), 4199; https://doi.org/10.3390/en18154199 - 7 Aug 2025
Viewed by 249
Abstract
Ice energy storage systems have gained significant attention as sustainable solutions for energy management, particularly in applications with fluctuating energy demands. This study aims to compare two different designs, a triple-tube heat exchanger (TTHE) and spherical ice balls, the latter being the most [...] Read more.
Ice energy storage systems have gained significant attention as sustainable solutions for energy management, particularly in applications with fluctuating energy demands. This study aims to compare two different designs, a triple-tube heat exchanger (TTHE) and spherical ice balls, the latter being the most widely used traditional design in the industry. The TTHE design was first analyzed theoretically, then optimized using Computational Fluid Dynamics (CFD) simulations, and validated by the literature. Finally, it was compared with spherical ice balls under identical conditions. The analyses were conducted for an ice storage volume of 1000 kg, with the complete solidification process designed to occur within 8 h. The results indicate that the TTHE reduced solidification time by 25% while simultaneously increasing energy storage by 8%. This study contributes to the advancement of sustainable energy technologies by providing a comparative analysis of spherical ice balls and triple-tube heat exchangers for optimizing ice storage systems. The implementation of a TTHE for thermal storage can lower energy costs, mitigate peak demand, and address the intermittency challenges associated with renewable energy sources. Full article
(This article belongs to the Section J1: Heat and Mass Transfer)
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32 pages, 5466 KiB  
Article
Comprehensive Energy and Economic Analysis of Selected Variants of a Large-Scale Photovoltaic Power Plant in a Temperate Climate
by Dennis Thom, Artur Bugała, Dorota Bugała and Wojciech Czekała
Energies 2025, 18(15), 4198; https://doi.org/10.3390/en18154198 - 7 Aug 2025
Viewed by 312
Abstract
In recent years, solar energy has emerged as one of the most advanced renewable energy sources, with its production capacity steadily growing. To maximize output and efficiency, choosing the right configuration for a specific location for these installations is crucial. This study uniquely [...] Read more.
In recent years, solar energy has emerged as one of the most advanced renewable energy sources, with its production capacity steadily growing. To maximize output and efficiency, choosing the right configuration for a specific location for these installations is crucial. This study uniquely integrates detailed multi-variant fixed-tilt PV system simulations with comprehensive economic evaluation under temperate climate conditions, addressing site-specific spatial constraints and grid integration considerations that have rarely been combined in previous works. In this paper, an energy and economic efficiency analysis for a photovoltaic power plant, located in central Poland, designed in eight variants (10°, 15°, 20°, 25°, 30° PV module inclination angle for a south orientation and 10°, 20°, 30° for an east–west orientation) for a limited building area of approximately 300,000 m2 was conducted. In PVSyst computer simulations, PVGIS-SARAH2 solar radiation data were used together with the most common data for describing the Polish local solar climate, called Typical Meteorological Year data (TMY). The most energy-efficient variants were found to be 20° S and 30° S, configurations with the highest surface production coefficient (249.49 and 272.68 kWh/m2) and unit production efficiency values (1123 and 1132 kWh/kW, respectively). These findings highlight potential efficiency gains of up to approximately 9% in surface production coefficient and financial returns exceeding 450% ROI, demonstrating significant economic benefits. In economic terms, the 15° S variant achieved the highest values of financial parameters, such as the return on investment (ROI) (453.2%), the value of the average annual share of profits in total revenues (56.93%), the shortest expected payback period (8.7 years), the value of the levelized cost of energy production (LCOE) (0.1 EUR/kWh), and one of the lowest costs of building 1 MWp of a photovoltaic farm (664,272.7 EUR/MWp). Among the tested variants of photovoltaic farms with an east–west geographical orientation, the most advantageous choice is the 10° EW arrangement. The results provide valuable insights for policymakers and investors aiming to optimize photovoltaic deployment in temperate climates, supporting the broader transition to renewable energy and alignment with national energy policy goals. Full article
(This article belongs to the Special Issue Development of Distributed Energy Systems Based on Renewable Energy Sources—Current Status and Development Prospects)
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21 pages, 2150 KiB  
Article
Collaborative Microgrids as Power Quality Improvement Nodes in Electricity Networks
by Michel Leseure, Hanaa Feleafel and Jovana Radulovic
Energies 2025, 18(15), 4197; https://doi.org/10.3390/en18154197 - 7 Aug 2025
Viewed by 246
Abstract
This paper explores the integration of microgrids within utility networks and distinguishes selfish from collaborative microgrids. Research has shown that selfish microgrids tend to increase volatility of order updates to power generators, whereas collaborative microgrids decrease that volatility, resulting in smoother, more controllable [...] Read more.
This paper explores the integration of microgrids within utility networks and distinguishes selfish from collaborative microgrids. Research has shown that selfish microgrids tend to increase volatility of order updates to power generators, whereas collaborative microgrids decrease that volatility, resulting in smoother, more controllable operations of networks. This paper proposes an analytical formula linking power volatility to power quality, i.e., to issues such as voltage dips, surges, and transients. These are known risks for disrupting the operation of utility grids, causing instability and jeopardising efficiency and reliability. As collaborative microgrids reduce volatility, they improve power quality. That argument is extended to propose that collaborative microgrids can act as quality improvements agents within wider networks. Full article
(This article belongs to the Special Issue Grid Integration of Renewable Energy: Latest Advances and Prospects)
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21 pages, 1113 KiB  
Article
Research on High-Frequency Modification Method of Industrial-Frequency Smelting Transformer Based on Parallel Connection of Multiple Windings
by Huiqin Zhou, Xiaobin Yu, Wei Xu and Weibo Li
Energies 2025, 18(15), 4196; https://doi.org/10.3390/en18154196 - 7 Aug 2025
Viewed by 220
Abstract
Under the background of “dual-carbon” strategy and global energy transition, the metallurgical industry, which accounts for 15–20% of industrial energy consumption, urgently needs to reduce the energy consumption and emission of DC power supply of electric furnaces. Aiming at the existing 400–800 V/≥3000 [...] Read more.
Under the background of “dual-carbon” strategy and global energy transition, the metallurgical industry, which accounts for 15–20% of industrial energy consumption, urgently needs to reduce the energy consumption and emission of DC power supply of electric furnaces. Aiming at the existing 400–800 V/≥3000 A industrial-frequency transformer-rectifier system with low efficiency, large volume, heat dissipation difficulties and other bottlenecks, this thesis proposes and realizes a high-frequency integrated DC power supply scheme for high-power electric furnaces: high-frequency transformer core and rectifier circuit are deeply integrated, which breaks through and reduces the volume of the system by more than 40%, and significantly reduces the iron consumption; multiple cores and three windings in parallel are used for the system. The topology of multiple cores and three windings in parallel enables several independent secondary stages to share the large current of 3000 A level uniformly, eliminating the local overheating and current imbalance; the combination of high-frequency rectification and phase-shift control strategy enhances the input power factor to more than 0.95 and cuts down the grid-side harmonics remarkably. The authors have completed the design of 100 kW prototype, magneto-electric joint simulation, thermal structure coupling analysis, control algorithm development and field comparison test, and the results show that the program compared with the traditional industrial-frequency system efficiency increased by 12–15%, the system temperature rise reduced by 20 K, electrode voltage increased by 10–15%, the input power of furnace increased by 12%, and the harmonic index meets the requirements of the traditional industrial-frequency system. The results show that the efficiency of this scheme is 12–15% higher than the traditional IF system, the temperature rise in the system is 20 K lower, the voltage at the electrode end is 10–15% higher, the input power of the furnace is increased by 12%, and the harmonic indexes meet the requirements of GB/T 14549, which verifies the value of the scheme for realizing high efficiency, miniaturization, and reliable DC power supply in metallurgy. Full article
(This article belongs to the Section F3: Power Electronics)
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26 pages, 3734 KiB  
Article
Impact of PM2.5 Pollution on Solar Photovoltaic Power Generation in Hebei Province, China
by Ankun Hu, Zexia Duan, Yichi Zhang, Zifan Huang, Tianbo Ji and Xuanhua Yin
Energies 2025, 18(15), 4195; https://doi.org/10.3390/en18154195 - 7 Aug 2025
Viewed by 336
Abstract
Atmospheric aerosols significantly impact solar photovoltaic (PV) energy generation through their effects on surface solar radiation. This study quantifies the impact of PM2.5 pollution on PV power output using observational data from 10 stations across Hebei Province, China (2018–2019). Our analysis reveals [...] Read more.
Atmospheric aerosols significantly impact solar photovoltaic (PV) energy generation through their effects on surface solar radiation. This study quantifies the impact of PM2.5 pollution on PV power output using observational data from 10 stations across Hebei Province, China (2018–2019). Our analysis reveals that elevated PM2.5 concentrations substantially attenuate solar irradiance, resulting in PV power losses reaching up to a 48.2% reduction in PV power output during severe pollution episodes. To capture these complex aerosol–radiation–PV interactions, we developed and compared the following six machine learning models: Support Vector Regression, Random Forest, Decision Tree, K-Nearest Neighbors, AdaBoost, and Backpropagation Neural Network. The inclusion of PM2.5 as a predictor variable systematically enhanced model performance across all algorithms. To further optimize prediction accuracy, we implemented a stacking ensemble framework that integrates multiple base learners through meta-learning. The optimal stacking configuration achieved superior performance (MAE = 0.479 MW, indicating an average prediction error of 479 kilowatts; R2 = 0.967, reflecting that 96.7% of the variance in power output is explained by the model), demonstrating robust predictive capability under diverse atmospheric conditions. These findings underscore the importance of aerosol–radiation interactions in PV forecasting and provide crucial insights for grid management in pollution-affected regions. Full article
(This article belongs to the Section B: Energy and Environment)
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30 pages, 7051 KiB  
Review
Review of Material-Handling Challenges in Energy Production from Biomass and Other Solid Waste Materials
by Tong Deng, Vivek Garg and Michael S. A. Bradley
Energies 2025, 18(15), 4194; https://doi.org/10.3390/en18154194 - 7 Aug 2025
Viewed by 305
Abstract
Biomass and other solid wastes create potential environmental and health hazards in our modern society. Conversion of the wastes into energy presents a promising avenue for sustainable energy generation. However, the feasibility of the approach is limited by the challenges in material handling [...] Read more.
Biomass and other solid wastes create potential environmental and health hazards in our modern society. Conversion of the wastes into energy presents a promising avenue for sustainable energy generation. However, the feasibility of the approach is limited by the challenges in material handling because of the special properties of the materials. Despite their critical importance, the complexities of material handling often evade scrutiny until operational implementation. This paper highlights the challenges inherent in standard solid material-handling processes, preceded by a concise review of common solid waste typologies and their physical properties, particularly those related to biomass and biowastes. It delves into the complexities of material flow, storage, compaction, agglomeration, separation, transport, and hazard management. Specialised characterisation techniques essential for informed process design are also discussed to mitigate operational risks. In conclusion, this paper emphasises the necessity of a tailored framework before the establishment of any further conversion processes. Given the heterogeneous nature of biomaterials, material-handling equipment must demonstrate adaptability to accommodate the substantial variability in material properties in large-scale production. This approach aims to enhance feasibility and efficacy of any energy conversion initiatives by using biomass or other solid wastes, thereby advancing sustainable resource utilisation and environmental stewardship. Full article
(This article belongs to the Special Issue The Sustainability of Energy Production from Biomass and Biofuel Technologies)
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24 pages, 19050 KiB  
Article
Innovative Deposition of AZO as Recombination Layer on Silicon Nanowire Scaffold for Potential Application in Silicon/Perovskite Tandem Solar Cell
by Grażyna Kulesza-Matlak, Marek Szindler, Magdalena M. Szindler, Milena Kiliszkiewicz, Urszula Wawrzaszek, Anna Sypień, Łukasz Major and Kazimierz Drabczyk
Energies 2025, 18(15), 4193; https://doi.org/10.3390/en18154193 - 7 Aug 2025
Viewed by 290
Abstract
Transparent conductive aluminum-doped zinc oxide (AZO) films were investigated as potential recombination layers for perovskite/silicon tandem solar cells, comparing the results of atomic layer deposition (ALD) and magnetron sputtering (MS) on vertically aligned silicon nanowire (SiNW) scaffolds. Conformality and thickness control were examined [...] Read more.
Transparent conductive aluminum-doped zinc oxide (AZO) films were investigated as potential recombination layers for perovskite/silicon tandem solar cells, comparing the results of atomic layer deposition (ALD) and magnetron sputtering (MS) on vertically aligned silicon nanowire (SiNW) scaffolds. Conformality and thickness control were examined by cross-sectional SEM/TEM and profilometry, revealing fully conformal ALD coatings with tunable thicknesses (40–120 nm) versus tip-capped, semi-uniform MS films (100–120 nm). Optical transmission measurements on glass substrates showed that both 120 nm ALD and MS layers exhibit interference maxima near 450–500 nm and 72–89% transmission across 800–1200 nm; the thinnest ALD films reached up to 86% near-IR transparency. Four-point probe analysis demonstrated that ALD reduces surface resistance from 1150 Ω/□ at 40 nm to 245 Ω/□ at 120 nm, while MS layers achieved 317 Ω/□ at 120 nm. These results delineate the balance between conformality, transparency, and conductivity, providing design guidelines for AZO recombination interfaces in next-generation tandem photovoltaics. Full article
(This article belongs to the Special Issue Perovskite Solar Cells and Tandem Photovoltaics)
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30 pages, 4254 KiB  
Article
Ultra-Short-Term Photovoltaic Power Prediction Based on Predictable Component Reconstruction and Spatiotemporal Heterogeneous Graph Neural Networks
by Yingjie Liu and Mao Yang
Energies 2025, 18(15), 4192; https://doi.org/10.3390/en18154192 - 7 Aug 2025
Viewed by 326
Abstract
Ultra-short-term PV power prediction (USTPVPP) results provide a basis for the development of intra-day rolling power generation plans. However, due to the feature information and the unpredictability of meteorology, the current ultra-short-term PV power prediction accuracy improvement still faces technical challenges. In this [...] Read more.
Ultra-short-term PV power prediction (USTPVPP) results provide a basis for the development of intra-day rolling power generation plans. However, due to the feature information and the unpredictability of meteorology, the current ultra-short-term PV power prediction accuracy improvement still faces technical challenges. In this paper, we propose a combined prediction framework that takes into account the reconfiguration of the predictable components of PV stations and the spatiotemporal heterogeneous maps. A circuit singular spectral decomposition (CISSD) intrinsic predictable component extraction method is adopted to obtain specific frequency components in sensitive meteorological variables, a mechanism based on radiation characteristics and PV power trend predictable component extraction and reconstruction is proposed to enhance power predictability, and a spatiotemporal heterogeneous graph neural network (STHGNN) combined with a Non-stationary Transformer (Ns-Transformer) combination architecture to achieve joint prediction for different PV components. The proposed method is applied to a PV power plant in Gansu, China, and the results show that the prediction method based on the proposed combined spatio-temporal heterogeneous graph neural network model combined with the proposed predictable component extraction achieves an average reduction of 6.50% in the RMSE, an average reduction of 2.50% in the MAE, and an average improvement of 11.93% in the R2 over the direct prediction method, respectively. Full article
(This article belongs to the Special Issue Advances on Solar Energy and Photovoltaic Devices)
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45 pages, 2014 KiB  
Article
Innovative Business Models Towards Sustainable Energy Development: Assessing Benefits, Risks, and Optimal Approaches of Blockchain Exploitation in the Energy Transition
by Aikaterini Papapostolou, Ioanna Andreoulaki, Filippos Anagnostopoulos, Sokratis Divolis, Harris Niavis, Sokratis Vavilis and Vangelis Marinakis
Energies 2025, 18(15), 4191; https://doi.org/10.3390/en18154191 - 7 Aug 2025
Viewed by 372
Abstract
The goals of the European Union towards the energy transition imply profound changes in the energy field, so as to promote sustainable energy development while fostering economic growth. To achieve these changes, the incorporation of sustainable technologies supporting decentralisation, energy efficiency, renewable energy [...] Read more.
The goals of the European Union towards the energy transition imply profound changes in the energy field, so as to promote sustainable energy development while fostering economic growth. To achieve these changes, the incorporation of sustainable technologies supporting decentralisation, energy efficiency, renewable energy production, and demand flexibility is of vital importance. Blockchain has the potential to change energy services towards this direction. To optimally exploit blockchain, innovative business models need to be designed, identifying the opportunities emerging from unmet needs, while also considering potential risks so as to take action to overcome them. In this context, the scope of this paper is to examine the opportunities and the risks that emerge from the adoption of blockchain in four innovative business models, while also identifying mitigation strategies to support and accelerate the energy transition, thus proposing optimal approaches of exploitation of blockchain in energy services. The business models concern Energy Performance Contracting with P4P guarantees, improved self-consumption in energy cooperatives, energy efficiency and flexibility services for natural gas boilers, and smart energy management for EV chargers and HVAC appliances. Firstly, the value proposition of the business models is analysed and results in a comprehensive SWOT analysis. Based on the findings of the analysis and consultations with relevant market actors, in combination with the examination of the relevant literature, risks are identified and evaluated through a qualitative assessment approach. Subsequently, specific mitigation strategies are proposed to address the detected risks. This research demonstrates that blockchain integration into these business models can significantly improve energy efficiency, reduce operational costs, enhance security, and support a more decentralised energy system, providing actionable insights for stakeholders to implement blockchain solutions effectively. Furthermore, according to the results, technological and legal risks are the most significant, followed by political, economic, and social risks, while environmental risks of blockchain integration are not as important. Strategies to address risks relevant to blockchain exploitation include ensuring policy alignment, emphasising economic feasibility, facilitating social inclusion, prioritising security and interoperability, consulting with legal experts, and using consensus algorithms with low energy consumption. The findings offer clear guidance for energy service providers, policymakers, and technology developers, assisting in the design, deployment, and risk mitigation of blockchain-enabled business models to accelerate sustainable energy development. Full article
(This article belongs to the Special Issue Towards Sustainable Energy Development: Energy Efficiency and Economic Growth)
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21 pages, 2930 KiB  
Article
Wake Losses, Productivity, and Cost Analysis of a Polish Offshore Wind Farm in the Baltic Sea
by Adam Rasiński and Ziemowit Malecha
Energies 2025, 18(15), 4190; https://doi.org/10.3390/en18154190 - 7 Aug 2025
Viewed by 556
Abstract
This study presents a comprehensive analysis of the long-term energy performance and economic viability of offshore wind farms planned for locations within the Polish Exclusive Economic Zone of the Baltic Sea. It focuses on the impact of wind farm layout, aerodynamic wake effects, [...] Read more.
This study presents a comprehensive analysis of the long-term energy performance and economic viability of offshore wind farms planned for locations within the Polish Exclusive Economic Zone of the Baltic Sea. It focuses on the impact of wind farm layout, aerodynamic wake effects, and rotor blade surface degradation. Using the Jensen wake model, modified Weibull wind speed distributions are computed for various turbine spacing configurations (5D, 8D, and 10D) and wake decay constants kw∈{0.02;0.03;0.05}. The results reveal a trade-off between turbine density and individual turbine efficiency: tighter spacing increases the total annual energy production (AEP) but also intensifies wake-induced losses. The study shows that cumulative losses due to wake effects can range from 16.5% to 38%, depending on the scenario considered. This corresponds to capacity factors ranging from 33.4% to 45.2%. Finally, lifetime productivity scenarios over 20 and 25 years are analyzed, and the levelized cost of electricity (LCOE) is calculated to assess the economic implications of design choices. The analysis reveals that, depending on the values of the considered parameters, the LCOE can range from USD 116.3 to 175.7 per MWh produced. The study highlights the importance of early stage optimization in maximizing both the energy yield and cost-efficiency in offshore wind farm developments. Full article
(This article belongs to the Special Issue Modern Technologies for Renewable Energy Development and Utilization: 5th Edition)
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15 pages, 3574 KiB  
Article
Optimizing Sunflower Husk Pellet Combustion for B2B Bioenergy Commercialization
by Penka Zlateva, Nevena Mileva, Mariana Murzova, Kalin Krumov and Angel Terziev
Energies 2025, 18(15), 4189; https://doi.org/10.3390/en18154189 - 7 Aug 2025
Viewed by 170
Abstract
This study analyses the potential of using sunflower husks as an energy source by producing bio-pellets and evaluating their combustion process in residential settings. As one of the leading sunflower producers in the European Union, Bulgaria generates significant agricultural residues with high, yet [...] Read more.
This study analyses the potential of using sunflower husks as an energy source by producing bio-pellets and evaluating their combustion process in residential settings. As one of the leading sunflower producers in the European Union, Bulgaria generates significant agricultural residues with high, yet underutilized, energy potential. This study employs a combination of experimental data and numerical modelling aided by ANSYS 2024 R1 to analyse the combustion of sunflower husk pellets in a hot water boiler. The importance of balanced air distribution for achieving optimal combustion, reduced emissions, and enhanced thermal efficiency is emphasized by the results of a comparison of two air supply regimes. It was found that a secondary air-dominated air supply regime results in a more uniform temperature field and a higher degree of oxidation of combustible components. These findings not only confirm the technical feasibility of sunflower husk pellets but also highlight their commercial potential as a sustainable, low-cost energy solution for agricultural enterprises and rural heating providers. The research indicates that there are business-to-business (B2B) market opportunities for biomass producers, boiler manufacturers, and energy distributors who wish to align themselves with EU green energy policies and the growing demand for solutions that support the circular economy. Full article
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27 pages, 1578 KiB  
Article
Tapio-Z Decoupling of the Valuation of Energy Sources, CO2 Emissions, and GDP Growth in the United States and China Using a Fuzzy Logic Model
by Rabnawaz Khan and Weiqing Zhuang
Energies 2025, 18(15), 4188; https://doi.org/10.3390/en18154188 - 7 Aug 2025
Viewed by 132
Abstract
Our contemporary society is powered by fossil fuels, which results in environmental catastrophes. The combustion of these materials results in the release of CO2, which accelerates the progression of climate change and its catastrophic consequences. The environmental repercussions of fossil fuel [...] Read more.
Our contemporary society is powered by fossil fuels, which results in environmental catastrophes. The combustion of these materials results in the release of CO2, which accelerates the progression of climate change and its catastrophic consequences. The environmental repercussions of fossil fuel extraction have been highlighted through research into alternative energy sources. This inquiry uses the Tapio-Z decoupling approach to assess energy inputs and emissions. Furthermore, the fuzzy logic model is used to inspect the economic growth of the USA and China, as well as the impact of environmental factors, energy sources, and utilization, through decoupling effects from 1994 to 2023. The findings are substantiated by the individual perspectives of the environmental factors regarding decoupling, which ultimately lead to the acquisition of valuable results. We anticipate a substantial reduction in the total volume of CO2 emissions in both the USA and China. Compared to China, the USA shows a significant increase in CO2 emissions due to its reliance on fossil fuels. It is evident that a comprehensive transition to renewable resources and a broad range of technology is required to mitigate CO2 emissions in high-energy zones. In their pursuit of sustainability, these two nations are making remarkable strides. The percentage change in CO2 emissions indicates that effective changes in economic growth, energy input, and energy utilization, particularly sustainable energy, transmute energy output, as does the sustained implementation of robust environmental protection policies. The percentage change in CO2 emissions indicates a remarkable transformation in energy input, energy consumption, and economic growth. This transition has been most visible in the areas of energy transformation, sustainability, and the maintenance of strong environmental protection measures. Full article
(This article belongs to the Special Issue Energy Transition and Environmental Sustainability: 3rd Edition)
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19 pages, 2394 KiB  
Article
Analysis of Offshore Wind Power Potential Considering Different Mesh Shapes in the Presence of Prevailing Wind and Deeper Water Depth: A Case Study in Akita, Japan
by Takaaki Furubayashi and Komei Tsujie
Energies 2025, 18(15), 4187; https://doi.org/10.3390/en18154187 - 7 Aug 2025
Viewed by 172
Abstract
With countries around the world required to change their energy systems to mitigate climate change, offshore wind power has become one of the most important renewable energy sources. This study aims to analyze the potential for offshore wind power generation based on the [...] Read more.
With countries around the world required to change their energy systems to mitigate climate change, offshore wind power has become one of the most important renewable energy sources. This study aims to analyze the potential for offshore wind power generation based on the water depth and annual average wind speed in the Akita region, Japan. A geographical information system was used not only for a conventional square mesh but also for a rectangular mesh when there is a prevailing wind, and a greater water depth was also considered. The results obtained indicate that the use of a rectangular mesh reduces the potential for implantable offshore wind turbines compared to a square mesh. It was also found that the potential for offshore wind power generation is significant up to a water depth of 500 m. Full article
(This article belongs to the Special Issue Offshore Wind Farms: Theory, Methods and Applications)
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20 pages, 2335 KiB  
Article
Critical Elements in Incinerator Bottom Ash from Solid Waste Thermal Treatment Plant
by Monika Chuchro and Barbara Bielowicz
Energies 2025, 18(15), 4186; https://doi.org/10.3390/en18154186 - 7 Aug 2025
Viewed by 160
Abstract
This study presents a comprehensive analysis of the chemical composition of bottom ash samples generated during municipal waste incineration. A total of 52 samples were collected and subjected to statistical analysis for 17 elements and 2 element sums using techniques such as correlation [...] Read more.
This study presents a comprehensive analysis of the chemical composition of bottom ash samples generated during municipal waste incineration. A total of 52 samples were collected and subjected to statistical analysis for 17 elements and 2 element sums using techniques such as correlation analysis and one-way ANOVA. The results confirm a high degree of heterogeneity in the elemental content, reflecting the variability of waste streams and combustion processes. Strong correlations were identified between certain elements, including Cu-Zn, Co-Ni, and HREE-LREE, indicating common sources and similar geochemical properties. The analysis also revealed significant seasonal variability in the content of Ba and Sr, with lower average values observed during the spring season and greater variability noted during summer and winter. Although Al and HREE did not reach classical significance levels, their distributions suggest possible seasonal differentiation. These findings underscore the need for long-term monitoring and seasonal analysis of incineration bottom ash composition to optimize resource recovery processes and assess environmental risk. The integration of chemical data with operational data on waste composition and combustion parameters may contribute to a better understanding of the variability of individual elements, ultimately supporting the development of effective strategies for ash management and element recovery. Full article
(This article belongs to the Special Issue Renewable Energy as a Mechanism for Managing Sustainable Development)
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13 pages, 6104 KiB  
Article
Light-Driven Enhancement of Oxygen Evolution for Clean Energy Conversion: Co3O4-TiO2/CNTs P-N Heterojunction Catalysts Enabling Efficient Carrier Separation and Reduced Overpotential
by Weicheng Zhang, Taotao Zeng, Yi Yu, Yuling Liu, Hao He, Ping Li and Zeyan Zhou
Energies 2025, 18(15), 4185; https://doi.org/10.3390/en18154185 - 7 Aug 2025
Viewed by 257
Abstract
In the renewable energy conversion system, water electrolysis technology is widely regarded as the core means to achieve clean hydrogen production. However, the anodic oxygen evolution reaction (OER) has become a key bottleneck limiting the overall water splitting efficiency due to its slow [...] Read more.
In the renewable energy conversion system, water electrolysis technology is widely regarded as the core means to achieve clean hydrogen production. However, the anodic oxygen evolution reaction (OER) has become a key bottleneck limiting the overall water splitting efficiency due to its slow kinetic process and high overpotential. This study proposes a novel Co3O4-TiO2/CNTs p-n heterojunction catalyst, which was synthesized by hydrothermal method and significantly improved OER activity by combining heterojunction interface regulation and light field enhancement mechanism. Under illumination conditions, the catalyst achieved an overpotential of 390 mV at a current density of 10 mA cm−2, which is superior to the performance of the dark state (410 mV) and single component Co3O4-TiO2 catalysts. The material characterization results indicate that the p-n heterojunction structure effectively promotes the separation and migration of photogenerated carriers and enhances the visible light absorption capability. This work expands the design ideas of energy catalytic materials by constructing a collaborative electric light dual field regulation system, providing a new strategy for developing efficient and low-energy water splitting electrocatalysts, which is expected to play an important role in the future clean energy production and storage field. Full article
(This article belongs to the Special Issue State-of-the-Art Research in Advanced Materials for Energy Storage Applications: 2nd Edition)
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26 pages, 2444 KiB  
Article
A Multi-Stage Feature Selection and Explainable Machine Learning Framework for Forecasting Transportation CO2 Emissions
by Mohammad Ali Sahraei, Keren Li and Qingyao Qiao
Energies 2025, 18(15), 4184; https://doi.org/10.3390/en18154184 - 7 Aug 2025
Viewed by 214
Abstract
The transportation sector is a major consumer of primary energy and is a significant contributor to greenhouse gas emissions. Sustainable transportation requires identifying and quantifying factors influencing transport-related CO2 emissions. This research aims to establish an adaptable, precise, and transparent forecasting structure [...] Read more.
The transportation sector is a major consumer of primary energy and is a significant contributor to greenhouse gas emissions. Sustainable transportation requires identifying and quantifying factors influencing transport-related CO2 emissions. This research aims to establish an adaptable, precise, and transparent forecasting structure for transport CO2 emissions of the United States. For this reason, we proposed a multi-stage method that incorporates explainable Machine Learning (ML) and Feature Selection (FS), guaranteeing interpretability in comparison to conventional black-box models. Due to high multicollinearity among 24 initial variables, hierarchical feature clustering and multi-step FS were applied, resulting in five key predictors: Total Primary Energy Imports (TPEI), Total Fossil Fuels Consumed (FFT), Annual Vehicle Miles Traveled (AVMT), Air Passengers-Domestic and International (APDI), and Unemployment Rate (UR). Four ML methods—Support Vector Regression, eXtreme Gradient Boosting, ElasticNet, and Multilayer Perceptron—were employed, with ElasticNet outperforming the others with RMSE = 45.53, MAE = 30.6, and MAPE = 0.016. SHAP analysis revealed AVMT, FFT, and APDI as the top contributors to CO2 emissions. This framework aids policymakers in making informed decisions and setting precise investments. Full article
(This article belongs to the Special Issue Integrated Solutions for Transportation and Energy Systems: Advancing Sustainable Mobility and Power Infrastructure)
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26 pages, 5304 KiB  
Article
Multi-Criteria Optimization and Techno-Economic Assessment of a Wind–Solar–Hydrogen Hybrid System for a Plateau Tourist City Using HOMER and Shannon Entropy-EDAS Models
by Jingyu Shi, Ran Xu, Dongfang Li, Tao Zhu, Nanyu Fan, Zhanghua Hong, Guohua Wang, Yong Han and Xing Zhu
Energies 2025, 18(15), 4183; https://doi.org/10.3390/en18154183 - 7 Aug 2025
Viewed by 354
Abstract
Hydrogen offers an effective pathway for the large-scale storage of renewable energy. For a tourist city located in a plateau region rich in renewable energy, hydrogen shows great potential for reducing carbon emissions and utilizing uncertain renewable energy. Herein, the wind–solar–hydrogen stand-alone and [...] Read more.
Hydrogen offers an effective pathway for the large-scale storage of renewable energy. For a tourist city located in a plateau region rich in renewable energy, hydrogen shows great potential for reducing carbon emissions and utilizing uncertain renewable energy. Herein, the wind–solar–hydrogen stand-alone and grid-connected systems in the plateau tourist city of Lijiang City in Yunnan Province are modeled and techno-economically evaluated by using the HOMER Pro software (version 3.14.2) with the multi-criteria decision analysis models. The system is composed of 5588 kW solar photovoltaic panels, an 800 kW wind turbine, a 1600 kW electrolyzer, a 421 kWh battery, and a 50 kW fuel cell. In addition to meeting the power requirements for system operation, the system has the capacity to provide daily electricity for 200 households in a neighborhood and supply 240 kg of hydrogen per day to local hydrogen-fueled buses. The stand-alone system can produce 10.15 × 106 kWh of electricity and 93.44 t of hydrogen per year, with an NPC of USD 8.15 million, an LCOE of USD 0.43/kWh, and an LCOH of USD 5.26/kg. The grid-connected system can generate 10.10 × 106 kWh of electricity and 103.01 ton of hydrogen annually. Its NPC is USD 7.34 million, its LCOE is USD 0.11/kWh, and its LCOH is USD 3.42/kg. This study provides a new solution for optimizing the configuration of hybrid renewable energy systems, which will develop the hydrogen economy and create low-carbon-emission energy systems. Full article
(This article belongs to the Section B: Energy and Environment)
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20 pages, 1749 KiB  
Article
Potential of Gas-Enhanced Oil Recovery (EOR) Methods for High-Viscosity Oil: A Core Study from a Kazakhstani Reservoir
by Karlygash Soltanbekova, Gaukhar Ramazanova and Uzak Zhapbasbayev
Energies 2025, 18(15), 4182; https://doi.org/10.3390/en18154182 - 7 Aug 2025
Viewed by 259
Abstract
At present, various advanced technologies for field development based on gas-enhanced oil recovery (EOR) methods are widely applied worldwide. These include high-pressure gas injection (hydrocarbon gases, nitrogen, flue gases), water-alternating-gas (WAG) injection, and carbon dioxide (CO2) flooding. This study presents the [...] Read more.
At present, various advanced technologies for field development based on gas-enhanced oil recovery (EOR) methods are widely applied worldwide. These include high-pressure gas injection (hydrocarbon gases, nitrogen, flue gases), water-alternating-gas (WAG) injection, and carbon dioxide (CO2) flooding. This study presents the results of filtration experiments investigating the application of gas EOR methods using core samples from a heavy oil reservoir. The primary objective of these experiments was to determine the oil displacement factor and analyze changes in interfacial tension upon injection of different gas agents. The following gases were utilized for modeling gas EOR processes: nitrogen (N2), carbon dioxide (CO2), and hydrocarbon gases (methane, propane). The core samples used in the study were obtained from the East Moldabek heavy oil field in Kazakhstan. Based on the results of the filtration experiments, carbon dioxide (CO2) injection was identified as the most effective gas EOR method in terms of increasing the oil displacement factor, achieving an incremental displacement factor of 5.06%. Other gas injection methods demonstrated lower efficiency. Full article
(This article belongs to the Section H1: Petroleum Engineering)
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18 pages, 8662 KiB  
Article
Synergy of Fly Ash and Surfactant on Stabilizing CO2/N2 Foam for CCUS in Energy Applications
by Jabir Dubaish Raib, Fujian Zhou, Tianbo Liang, Anas A. Ahmed and Shuai Yuan
Energies 2025, 18(15), 4181; https://doi.org/10.3390/en18154181 - 6 Aug 2025
Viewed by 262
Abstract
The stability of nitrogen gas foam hinders its applicability in petroleum applications. Fly ash nanoparticles and clay improve the N2 foam stability, and flue gas foams provide a cost-effective solution for carbon capture, utilization, and storage (CCUS). This study examines the stability, [...] Read more.
The stability of nitrogen gas foam hinders its applicability in petroleum applications. Fly ash nanoparticles and clay improve the N2 foam stability, and flue gas foams provide a cost-effective solution for carbon capture, utilization, and storage (CCUS). This study examines the stability, volume, and bubble structure of foams formed using two anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS), along with the cationic surfactant cetyltrimethylammonium bromide (CTAB), selected for their comparable interfacial tension properties. Analysis of foam stability and volume and bubble structure was conducted under different CO2/N2 mixtures, with half-life and initial foam volume serving as the evaluation criteria. The impact of fly ash and clay on SDS-N2 foam was also evaluated. The results showed that foams created with CTAB, SDBS, and SDS exhibit the greatest stability in pure nitrogen, attributed to low solubility in water and limited gas diffusion. SDS showed the highest foam strength attributable to its comparatively low surface tension. The addition of fly ash and clay significantly improved foam stability by migrating to the gas–liquid interface, creating a protective barrier that reduced drainage. Both nano fly ash and clay improved the half-life of nitrogen foam by 11.25 times and increased the foam volume, with optimal concentrations identified as 5.0 wt% for fly ash and 3.0 wt% for clay. This research emphasizes the importance of fly ash nanoparticles in stabilizing foams, therefore optimizing a foam system for enhanced oil recovery (EOR). Full article
(This article belongs to the Special Issue Subsurface Energy and Environmental Protection 2024)
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33 pages, 3534 KiB  
Review
Enhancing the Performance of Active Distribution Grids: A Review Using Metaheuristic Techniques
by Jesús Daniel Dávalos Soto, Daniel Guillen, Luis Ibarra, José Ezequiel Santibañez-Aguilar, Jesús Elias Valdez-Resendiz, Juan Avilés, Meng Yen Shih and Antonio Notholt
Energies 2025, 18(15), 4180; https://doi.org/10.3390/en18154180 - 6 Aug 2025
Viewed by 331
Abstract
The electrical power system is composed of three essential sectors, generation, transmission, and distribution, with the latter being crucial for the overall efficiency of the system. Enhancing the capabilities of active distribution networks involves integrating various advanced technologies such as distributed generation units, [...] Read more.
The electrical power system is composed of three essential sectors, generation, transmission, and distribution, with the latter being crucial for the overall efficiency of the system. Enhancing the capabilities of active distribution networks involves integrating various advanced technologies such as distributed generation units, energy storage systems, banks of capacitors, and electric vehicle chargers. This paper provides an in-depth review of the primary strategies for incorporating these technologies into the distribution network to improve its reliability, stability, and efficiency. It also explores the principal metaheuristic techniques employed for the optimal allocation of distributed generation units, banks of capacitors, energy storage systems, electric vehicle chargers, and network reconfiguration. These techniques are essential for effectively integrating these technologies and optimizing the active distribution network by enhancing power quality and voltage level, reducing losses, and ensuring operational indices are maintained at optimal levels. Full article
(This article belongs to the Section K: State-of-the-Art Energy Related Technologies)
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