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Next Generation of Electric Vehicles: AI-Driven Approaches for Predictive Maintenance and Battery Management
Building Energy Performance Assessment via BIM and ML Techniques
Advanced Deep Learning Algorithms for Energy Optimization of Smart Cities
Solar Thermochemical Fuel Production: A Novel, Validated Multiphysics Reactor Model for the Reduction–Oxidation of Nonstoichiometric Redox Cycles
Lithium Battery Degradation and Failure Mechanisms

Journal Description

Energies

Energies is a peer-reviewed, open access journal of related scientific research, technology development, engineering policy, and management studies related to the general field of energy, from technologies of energy supply, conversion, dispatch, and final use to the physical and chemical processes behind such technologies. Energies is published semimonthly online by MDPI. The European Biomass Industry Association (EUBIA), Association of European Renewable Energy Research Centres (EUREC), Institute of Energy and Fuel Processing Technology (ITPE), International Society for Porous Media (InterPore), CYTED and others are affiliated with Energies and their members receive a discount on the article processing charges.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, SCIE (Web of Science), Ei Compendex, RePEc, Inspec, CAPlus / SciFinder, and other databases.
Journal Rank: CiteScore - Q1 (Control and Optimization)
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 16.8 days after submission; acceptance to publication is undertaken in 2.9 days (median values for papers published in this journal in the second half of 2024).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Sections: published in 41 topical sections.
Testimonials: See what our editors and authors say about Energies.
Companion journals for Energies include: Gases, Nanoenergy Advances, Solar, Wind, Energy Storage and Applications and Bioresources and Bioproducts.

Impact Factor: 3.0 (2023); 5-Year Impact Factor: 3.0 (2023)

Imprint Information Journal Flyer Open Access ISSN: 1996-1073

Latest Articles

16 pages, 16782 KiB

Open AccessArticle

S-Transform Based Time–Frequency Evaluation of Dynamic Stray Current in Zero-Resistance Converter System

by Xiangxuan Sun, Xiaofeng Yang, Runda Zhao, Zhenshuai Wang, Maolu Chen and Trillion Q. Zheng

Energies 2025, 18(7), 1594; https://doi.org/10.3390/en18071594 (registering DOI) - 23 Mar 2025

In DC urban rail transit, stray current causes unneglectable electrochemical corrosion to metallic structures near running rails. In view of the low-frequency and non-stationary distribution of dynamic stray current due to multiple trains in lines, its signal characteristic is significant for the corrosion [...] Read more.

In DC urban rail transit, stray current causes unneglectable electrochemical corrosion to metallic structures near running rails. In view of the low-frequency and non-stationary distribution of dynamic stray current due to multiple trains in lines, its signal characteristic is significant for the corrosion degree prediction and mitigation performance evaluation. While zero-resistance converter system (ZRCS) is introduced for stray current mitigation, further evaluation of its mitigation performance is essential to field application. Considering that the Fourier transform processing non-stationary signals cannot estimate its frequency-domain features accurately, this paper introduces S-transform to extract the time–frequency characteristics of dynamic stray current in ZRCS. Moreover, the dynamic stray current mitigation performance of ZRCS is verified through time–frequency analysis results. Full article

(This article belongs to the Section F: Electrical Engineering)

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23 pages, 4866 KiB

Open AccessArticle

Reverse Oil Flow Characterization in Transformer Windings: A Fluid-Thermal Network Approach

by Lujia Wang, Jianghao Qi, Yifan Chen, Lebin Zhang and Jianwen Zhang

Energies 2025, 18(7), 1593; https://doi.org/10.3390/en18071593 (registering DOI) - 22 Mar 2025

When the inlet flow velocity in the disc-type winding region of an oil-immersed transformer operates within a high Reynolds number range, it leads to an uneven distribution of oil flow. This phenomenon results in the abnormal occurrence of reverse oil flow in the [...] Read more.

When the inlet flow velocity in the disc-type winding region of an oil-immersed transformer operates within a high Reynolds number range, it leads to an uneven distribution of oil flow. This phenomenon results in the abnormal occurrence of reverse oil flow in the bottom oil ducts, causing the hotspot temperature to rise instead of decrease. To address this issue, a three-node flow resistance module was introduced at the intersection of T-shaped oil ducts based on the flow paths of oil in the main and branch ducts within the disc-type winding region. A flow network model for the transformer winding region was subsequently constructed. The accuracy of the model was validated through CFD simulations and experiments conducted on a transformer winding region test platform, with a maximum relative error of 4.02%. The model successfully predicted the flow distribution of the cooling oil within the winding region. Furthermore, by considering the structural characteristics of the winding region and the principles of heat transfer, particular attention was given to variations in local Nusselt number correlations. This led to the development of a thermal network model tailored to the winding region experiencing reverse oil flow. Comparative analysis of the model’s calculation results yielded a maximum relative error of only 1.12%, demonstrating its ability to rapidly and accurately elucidate the reverse oil flow effect. This study provides a theoretical foundation for the identification and mitigation of reverse oil flow in future applications. Full article

(This article belongs to the Special Issue Advances in Design, Operation and Maintenance Technology for Electric Power Equipment)

21 pages, 1766 KiB

Open AccessReview

Fuzzy-Ball Fluids: Fundamentals, Mechanisms, and Prospects for Clean Energy and Oilfield Applications

by Long Jin, Chinedu J. Okere, Qin Guo and Lihui Zheng

Energies 2025, 18(7), 1592; https://doi.org/10.3390/en18071592 (registering DOI) - 22 Mar 2025

Fuzzy-ball fluids have emerged as a novel class of chemical sealaplugging materials with significant potential for enhancing both traditional oilfield operations and clean energy technologies. They are characterized by unique viscoelastic properties, plugging, self-adapting capabilities, and the ability to regulate multi-phase fluid flow [...] Read more.

Fuzzy-ball fluids have emerged as a novel class of chemical sealaplugging materials with significant potential for enhancing both traditional oilfield operations and clean energy technologies. They are characterized by unique viscoelastic properties, plugging, self-adapting capabilities, and the ability to regulate multi-phase fluid flow under extreme subsurface conditions. In oilfield applications, fuzzy-ball fluids offer solutions for drilling, hydraulic fracturing, workover operations, and enhanced oil recovery in shallow, deep, and offshore reservoirs. In clean energy fields such as hydrogen storage, carbon capture, utilization, and storage, and geothermal energy, they show promise in improving energy efficiency, storage security, and environmental sustainability. This review explores the fundamental principles and mechanisms behind fuzzy-ball fluids, examines their field applications in the oil and gas industry, and investigates their potential in emerging clean energy technologies. This study also identifies key challenges, including material stability, economic viability, and environmental impact, which must be addressed to ensure the successful deployment of fuzzy-ball fluids. Furthermore, we outline future research directions, emphasizing material optimization, large-scale field trials, environmental impact assessments, and interdisciplinary collaboration to accelerate the commercialization of fuzzy-ball fluid technologies. By addressing these challenges, fuzzy-ball fluids could play a transformative role in both conventional and clean energy fields, contributing to sustainable and efficient energy solutions. Full article

(This article belongs to the Section H: Geo-Energy)

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19 pages, 6828 KiB

Open AccessArticle

Experimental Study on Heat Transfer Coefficients in an Office Room with a Radiant Ceiling During Low Heating Loads

by Piotr Michalak

Energies 2025, 18(7), 1591; https://doi.org/10.3390/en18071591 (registering DOI) - 22 Mar 2025

Estimation of the heating or cooling capacity of radiant systems requires selecting appropriate internal heat transfer coefficients by convection (CHTCs) and radiation (RHTCs). Due to practical reasons, their measurement during the normal use of buildings is very troublesome. This study attempts to present [...] Read more.

Estimation of the heating or cooling capacity of radiant systems requires selecting appropriate internal heat transfer coefficients by convection (CHTCs) and radiation (RHTCs). Due to practical reasons, their measurement during the normal use of buildings is very troublesome. This study attempts to present the results of measurements of CHTCs and RHTCs taken in an office room located in a passive building with a heated concrete ceiling. Special attention was paid to the proper choice of reference temperatures. For better accuracy, view factors for radiant heat exchange were calculated using Matlab. Average values of CHTCs and RHTCs calculated from measurements amounted to 0.80 W/m²K and 5.66 W/m²K. RHTCs showed a significant correlation against the ceiling temperature, with the coefficient of determination being R² = 0.96. Finally, the total heat transfer coefficient of 6.47 W/m²K was obtained. These values are comparable with other studies and standards and confirm that measurements were performed correctly. Full article

(This article belongs to the Special Issue Energy and Buildings: Thermal Storage, Emissions, Transports, Control and Their Effects)

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16 pages, 280 KiB

Open AccessArticle

Harnessing a Renewable Resource for Sustainability: The Role of Geothermal Energy in Italy’s Business Sector

by Angelo Arcuri, Lorenzo Giolli and Cosimo Magazzino

Energies 2025, 18(7), 1590; https://doi.org/10.3390/en18071590 (registering DOI) - 22 Mar 2025

Addressing critical challenges such as climate change, environmental degradation, and resource depletion requires a swift transition to efficient and environmentally friendly energy solutions. Among these, geothermal energy is recognized for its dependability, low environmental impact, and versatility. This study investigates the role of [...] Read more.

Addressing critical challenges such as climate change, environmental degradation, and resource depletion requires a swift transition to efficient and environmentally friendly energy solutions. Among these, geothermal energy is recognized for its dependability, low environmental impact, and versatility. This study investigates the role of geothermal energy in Italy’s business sector, examining its impact on companies and social perception. It specifically evaluates how communicating geological, hydrological, and atmospheric risks associated with geothermal projects influences firms’ likelihood of experiencing social acceptance challenges. Additionally, this research quantifies the impact of geothermal energy adoption on companies’ energy costs and CO₂ emissions. The analysis further explores the long-term implications of expanding the use of this renewable resource through sensitivity analysis, focusing on its effects on emissions and costs. The findings indicate that firms communicating geothermal-related risks are less likely to experience social acceptance challenges compared to those that do not. Moreover, this study shows that the use of geothermal energy positively impacts firms’ business and environmental performance by reducing energy costs and CO₂ emissions. Sensitivity analysis demonstrates that increasing the proportion of geothermal energy usage amplifies these benefits, thereby enhancing firms’ competitiveness. This research provides a comprehensive framework for promoting geothermal energy integration in business operations, offering valuable insights to support the global shift toward sustainable energy systems. Full article

(This article belongs to the Special Issue Policy and Economic Analysis of Energy Systems)

30 pages, 1061 KiB

Open AccessReview

Beyond the First Generation of Wind Modeling for Resource Assessment and Siting: From Meteorology to Uncertainty Quantification

by Mark Kelly

Energies 2025, 18(7), 1589; https://doi.org/10.3390/en18071589 (registering DOI) - 22 Mar 2025

Increasingly large turbines have led to a transition from surface-based `bottom–up’ wind flow modeling and meteorological understanding, to more complex modeling of wind resources, energy yields, and site assessment. More expensive turbines, larger windfarms, and maturing commercialization have meant that uncertainty quantification (UQ) [...] Read more.

Increasingly large turbines have led to a transition from surface-based `bottom–up’ wind flow modeling and meteorological understanding, to more complex modeling of wind resources, energy yields, and site assessment. More expensive turbines, larger windfarms, and maturing commercialization have meant that uncertainty quantification (UQ) of such modeling has become crucial for the wind industry. In this paper, we outline the meteorological roots of wind modeling and why it was initially possible, advancing to the more complex models needed for large wind turbines today, and the tradeoffs and implications of using such models. Statistical implications of how data are averaged and/or split in various resource assessment methodologies are also examined, and requirements for validation of classic and complex models are considered. Uncertainty quantification is outlined, and its current practice on the `wind’ side of the industry is discussed, including the emerging standard for such. Demonstrative examples are given for uncertainty propagation and multi-project performance versus uncertainty, with a final reminder about the distinction between UQ and risk. Full article

(This article belongs to the Special Issue The Application of Weather and Climate Research in the Energy Sector)

25 pages, 9188 KiB

Open AccessReview

Recent Advances in Translational Electromagnetic Energy Harvesting: A Review

by Marco Valerio Perrozzi, Mirco Lo Monaco and Aurelio Somà

Energies 2025, 18(7), 1588; https://doi.org/10.3390/en18071588 (registering DOI) - 22 Mar 2025

Wireless Sensor Nodes (WSNs) are becoming increasingly popular in various industrial sectors due to their capability of real-time remote monitoring of assets. Powering these devices with vibrational energy harvesters (EHs) provides multiple benefits, such as minimal maintenance and ideally infinite lifespan. Among the [...] Read more.

Wireless Sensor Nodes (WSNs) are becoming increasingly popular in various industrial sectors due to their capability of real-time remote monitoring of assets. Powering these devices with vibrational energy harvesters (EHs) provides multiple benefits, such as minimal maintenance and ideally infinite lifespan. Among the vibrational harvesters, translational electromagnetic ones (TEMEHs) are a promising solution due to their simple and reliable architecture and their ability to harvest energy at low frequencies. However, a major challenge is achieving a high power density. In this paper, recent literature about this typology of harvesters is reviewed. Different techniques to tune the resonance frequencies to the fundamental frequencies of the ambient vibrations are analyzed, such as non-linearities and multi-DOF configurations. The harvesters are classified on the basis of the suspension type, highlighting advantages and disadvantages. A final comparison is carried out in terms of NPD and FoMv, two indexes that evaluate power density in relation to size and excitation amplitudes. Full article

(This article belongs to the Section D: Energy Storage and Application)

15 pages, 907 KiB

Open AccessArticle

Energy Efficiency Optimization in Swarm Robotics for Smart Photovoltaic Monitoring

by Dimitris Ziouzios, Nikolaos Baras, Minas Dasygenis, Vayos Karayannis and Constantinos Tsanaktsidis

Energies 2025, 18(7), 1587; https://doi.org/10.3390/en18071587 (registering DOI) - 22 Mar 2025

Photovoltaic park (PV) and power generator monitoring is a crucial activity that calls for effective coverage path planning. Artificial intelligence and particularly swarm robotics have brought new methods to tasks such as coverage path planning by having multiple robots work together to cover [...] Read more.

Photovoltaic park (PV) and power generator monitoring is a crucial activity that calls for effective coverage path planning. Artificial intelligence and particularly swarm robotics have brought new methods to tasks such as coverage path planning by having multiple robots work together to cover a specific area. Nonetheless, enhancing energy efficiency in these systems continues to be a crucial obstacle, particularly with the growing focus on sustainability. This research investigates techniques to enhance energy efficiency in swarm robotics, focusing on coverage path planning assignments. The proposed approach merges advanced swarm robotics algorithms with energy-efficient methods to reduce power consumption while still ensuring effective coverage. Thorough simulations in simulated environments of Western Macedonia assess the efficiency of the proposed approach. Even though the proposed approach has a longer convergence time compared to a generic ACO approach, the findings of the simulations indicate that the MOACO approach has substantial enhancements up to 22% in path travel time, in terms of solution quality and energy consumption metrics. The findings of the present work offer valuable insights into the design of sustainable robotic systems and underscore the potential of swarm robotics in achieving efficient coverage path planning. This study adds to the overall objective of creating eco-friendly technologies in robotics, leading to upcoming advancements in the industry. Full article

(This article belongs to the Special Issue Smart Cities and the Need for Green Energy)

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22 pages, 4800 KiB

Open AccessArticle

Strategic Bidding to Increase the Market Value of Variable Renewable Generators in Electricity Markets

by Vivian Sousa and Hugo Algarvio

Energies 2025, 18(7), 1586; https://doi.org/10.3390/en18071586 (registering DOI) - 22 Mar 2025

The 2050 global ambition for a carbon-neutral society is increasing the penetration of the most competitive variable renewable technologies, onshore wind and solar PV. These technologies are known for their near-zero marginal costs but highly variable time-dependent generation. Power systems with major penetrations [...] Read more.

The 2050 global ambition for a carbon-neutral society is increasing the penetration of the most competitive variable renewable technologies, onshore wind and solar PV. These technologies are known for their near-zero marginal costs but highly variable time-dependent generation. Power systems with major penetrations of variable generation need high balancing flexibility to guarantee their stability by maintaining the equilibrium between demand and supply. Electricity markets were designed for dispatchable technologies. Support schemes are used to incentivize and de-risk the investment in variable renewables, since actual market designs are riskier for their active participation. This study presents three strategic bidding strategies for the active participation of variable renewables in electricity markets based on probabilistic quantile-based forecasts. This case study examines the levels of active market participation for a wind power producer (WPP) in the Iberian electricity market and the Portuguese balancing markets, where WPPs are financially responsible for imbalances and operate without support schemes in the first and second stages of the Iberian market designs. Results from this study indicate that the WPP has the potential to increase its market value between 36% and 155% if participating in the tertiary and secondary balancing markets completely adapted to its design, respectively. However, considering the use of strategic bidding in actual market designs, by participating in the secondary reserve, the WPP can increase its market value by 10% and 45% when compared with perfect foresight and operational cases, respectively. Full article

(This article belongs to the Topic Market Integration of Renewable Generation)

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15 pages, 5405 KiB

Open AccessArticle

Off-Grid Smoothing Control Strategy for Dual Active Bridge Energy Storage System Based on Voltage Droop Control

by Chunhui Liu, Cai Xu, Yinfu Bao, Haoran Chen, Xiaolu Chen, Min Chen, Feng Jiang and Zhaopei Liang

Energies 2025, 18(7), 1585; https://doi.org/10.3390/en18071585 (registering DOI) - 22 Mar 2025

Energy storage systems based on dual active bridge (DAB) converters are a critical component of DC microgrid systems. To address power oscillations and system stability issues caused by power deficits during the off-grid operation of DC microgrids, a control strategy for DAB energy [...] Read more.

Energy storage systems based on dual active bridge (DAB) converters are a critical component of DC microgrid systems. To address power oscillations and system stability issues caused by power deficits during the off-grid operation of DC microgrids, a control strategy for DAB energy storage systems based on voltage droop control is proposed. By analyzing the internal operational mechanisms of DAB power electronic converters and integrating voltage droop equations, a small-signal model is constructed to deeply investigate the dynamic characteristics of DAB energy storage systems under off-grid conditions. Using the Nyquist stability criterion, appropriate voltage droop coefficients are selected to enhance system stability. Finally, a DC microgrid model is built on the MATLAB/Simulink simulation platform. Through the rational design of the droop coefficients, the overshoot of the power response is reduced from 28.87% to 4.27%, and settling time is effectively shortened while oscillations are suppressed. The simulation results validate the correctness and effectiveness of the theoretical framework proposed in this study. Full article

(This article belongs to the Special Issue Studies of Microgrids for Electrified Transportation)

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16 pages, 4744 KiB

Open AccessArticle

An Enhanced NSGA-II Algorithm with Parameter Categorization for Computational-Efficient Multi-Objective Optimization of Active Glass Curtain Wall Shading Systems

by Dezhao Tang and Zhiyong Wang

Energies 2025, 18(7), 1584; https://doi.org/10.3390/en18071584 (registering DOI) - 22 Mar 2025

To address the limitations of the Non-Dominated Sorting Genetic Algorithm (NSGA-II) in optimizing active glass curtain wall shading systems—particularly its suboptimal convergence efficiency and high computational demands—this study proposes an improved NSGA-II algorithm incorporating parameter categorization. Shading system parameters (e.g., slat width, angle, [...] Read more.

To address the limitations of the Non-Dominated Sorting Genetic Algorithm (NSGA-II) in optimizing active glass curtain wall shading systems—particularly its suboptimal convergence efficiency and high computational demands—this study proposes an improved NSGA-II algorithm incorporating parameter categorization. Shading system parameters (e.g., slat width, angle, separation, and blind-to-glass distance) are classified into distinct categories based on their character and optimized sequentially. This phased approach reduces the search space dimensionality, lowering computational complexity while maintaining optimization accuracy. The framework integrates user preferences and climatic adaptability to balance energy efficiency and glare mitigation. The louver parameters were optimized under the same experimental conditions, and the enhanced algorithm exhibits 49% lower energy consumption values and 5% smaller visual discomfort time duration compared to the baseline algorithm in the optimization outcomes. Full article

(This article belongs to the Topic Building Energy and Environment, 2nd Edition)

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24 pages, 7462 KiB

Open AccessArticle

Multi-Time-Scale Layered Energy Management Strategy for Integrated Production, Storage, and Supply Hydrogen Refueling Stations Based on Flexible Hydrogen Load Characteristics of Ports

by Zhuoyu Jiang, Rujie Liu, Weiwei Guan, Lei Xiong, Changli Shi and Jingyuan Yin

Energies 2025, 18(7), 1583; https://doi.org/10.3390/en18071583 (registering DOI) - 22 Mar 2025

Aiming at resolving the problem of stable and efficient operation of integrated green hydrogen production, storage, and supply hydrogen refueling stations at different time scales, this paper proposes a multi-time-scale hierarchical energy management strategy for integrated green hydrogen production, storage, and supply hydrogen [...] Read more.

Aiming at resolving the problem of stable and efficient operation of integrated green hydrogen production, storage, and supply hydrogen refueling stations at different time scales, this paper proposes a multi-time-scale hierarchical energy management strategy for integrated green hydrogen production, storage, and supply hydrogen refueling station (HFS). The proposed energy management strategy is divided into two layers. The upper layer uses the hourly time scale to optimize the operating power of HFS equipment with the goal of minimizing the typical daily operating cost, and proposes a parameter adaptive particle swarm optimization (PSA-PSO) solution algorithm that introduces Gaussian disturbance and adaptively adjusts the learning factor, inertia weight, and disturbance step size of the algorithm. Compared with traditional optimization algorithms, it can effectively improve the ability to search for the optimal solution. The lower layer uses the minute-level time scale to suppress the randomness of renewable energy power generation and hydrogen load consumption in the operation of HFS. A solution algorithm based on stochastic model predictive control (SMPC) is proposed. The Latin hypercube sampling (LHS) and simultaneous backward reduction methods are used to generate and reduce scenarios to obtain a set of high-probability random variable scenarios and bring them into the MPC to suppress the disturbance of random variables on the system operation. Finally, real operation data of a HFS in southern China are used for example analysis. The results show that the proposed energy management strategy has a good control effect in different typical scenarios. Full article

(This article belongs to the Special Issue Energy Storage Technologies and Applications for Smart Grids)

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21 pages, 1387 KiB

Open AccessArticle

Optimizing Corporate Energy Choices: A Framework for the Net-Zero Emissions Transition

by Chun-Hsu Lin, Lih-Chyi Wen and Jia-Cheh Lo

Energies 2025, 18(7), 1582; https://doi.org/10.3390/en18071582 (registering DOI) - 21 Mar 2025

For the net-zero emission goal by 2050, the government of Taiwan has mandated large electricity consumers to utilize 10% green electricity to mitigate carbon emissions. Major enterprises face challenges in selecting appropriate green power options and integrating the benefits of carbon reduction into [...] Read more.

For the net-zero emission goal by 2050, the government of Taiwan has mandated large electricity consumers to utilize 10% green electricity to mitigate carbon emissions. Major enterprises face challenges in selecting appropriate green power options and integrating the benefits of carbon reduction into corporate governance decision-making. This study aims to optimize the combination of various green power options through a system dynamics approach, incorporating existing power purchase conditions and electricity consumption data from enterprises. In addition, by utilizing financial estimations with the monetization of environmental benefits, we constructed a more complete evaluation model for enterprises transitioning to green power. The results indicate low investment returns in various green energy portfolios. However, if power storage equipment is utilized to participate in auxiliary services, the investment return of green energy can be significantly enhanced. This evaluation model is also available online for business professionals across various sectors to explore and reference. Full article

(This article belongs to the Collection Energy Transition Towards Carbon Neutrality)

21 pages, 1501 KiB

Open AccessArticle

High-Efficiency Cogeneration: A Viable Solution for the Decarbonization of Cities with District Heating Systems

by Pavel Atănăsoae, Radu Dumitru Pentiuc and Laurențiu Dan Milici

Energies 2025, 18(7), 1581; https://doi.org/10.3390/en18071581 - 21 Mar 2025

In a global context marked by increasingly evident climate change and an urgent need to reduce carbon emissions, efficient and environmentally friendly energy solutions are no longer just an option, but a necessity. Decarbonizing cities is an essential process for combating climate change [...] Read more.

In a global context marked by increasingly evident climate change and an urgent need to reduce carbon emissions, efficient and environmentally friendly energy solutions are no longer just an option, but a necessity. Decarbonizing cities is an essential process for combating climate change and creating a sustainable urban environment. This article provides an analysis of the decarbonization possibilities of the building heating sector in the case of cities with district heating systems. A case study referring to the district heating system of Suceava city, Romania, is provided. The results of this study show a significant reduction in carbon emissions per unit of thermal energy delivered (95.97%) from the district heating system after 2015 because of the change in technology and primary energy source (cogeneration and biomass). Also, a comparative analysis is provided: district heating vs. individual heating in terms of carbon dioxide (CO₂) emissions for the same amount of heat supplied to end consumers in 2023. The comparative analysis highlights a difference in CO₂ emission of 81.66% (0.220 kg CO₂/kWh for individual heating and 0.040 kg CO₂/kWh for district heating). The implications of high-efficiency cogeneration in the decarbonization of the building heating sector are analyzed and highlighted. Full article

(This article belongs to the Special Issue Analysis of Cogeneration Systems and Electricity Consumption—Second Edition)

28 pages, 2827 KiB

Open AccessArticle

Cooperative Sleep and Energy-Sharing Strategy for a Heterogeneous 5G Base Station Microgrid System Integrated with Deep Learning and an Improved MOEA/D Algorithm

by Ming Yan, Tuanfa Qin, Wenhao Guo and Yongle Hu

Energies 2025, 18(7), 1580; https://doi.org/10.3390/en18071580 - 21 Mar 2025

With the rapid growth of heterogeneous fifth-generation (5G) communication networks and a surge in global mobile traffic, energy consumption in mobile network systems has increased significantly. This underscores the need for energy-efficient networks that lower operational costs and carbon emissions, leading to a [...] Read more.

With the rapid growth of heterogeneous fifth-generation (5G) communication networks and a surge in global mobile traffic, energy consumption in mobile network systems has increased significantly. This underscores the need for energy-efficient networks that lower operational costs and carbon emissions, leading to a focus on microgrids powered by renewable energy. However, accurately predicting base station traffic demand and optimizing energy consumption while maximizing green energy usage—especially concerning quality of service (QoS) for users—remains a challenge. This paper proposes a cooperative sleep and energy-sharing strategy for heterogeneous 5G base station microgrid (BSMG) systems, utilizing deep learning and an improved multi-objective evolutionary algorithm based on decomposition (MOEA/D). We present a reference scenario for a 5G BSMG system comprising a central and sub-base station microgrid. A prediction model was developed, integrating a convolutional neural network with a dual attention mechanism and bidirectional long short-term memory to determine the operational status of BSMGs. Our cooperative strategy addresses QoS requirements and uses the enhanced MOEA/D to improve performance. Numerical results indicate that our approach achieves significant energy savings while ensuring accurate predictions of BSMG energy demands through a multi-objective evolutionary algorithm based on decomposition. Full article

(This article belongs to the Section F: Electrical Engineering)

16 pages, 909 KiB

Open AccessArticle

Assessment of Risks of Voltage Quality Decline in Load Nodes of Power Systems

by Pylyp Hovorov, Roman Trishch, Romualdas Ginevičius, Vladislavas Petraškevičius and Karel Šuhajda

Energies 2025, 18(7), 1579; https://doi.org/10.3390/en18071579 - 21 Mar 2025

The results of numerous studies show that the control of power grid modes is carried out mainly using a technical criterion. The economic criterion is taken into account through the use of complex and inaccurate models that do not accurately predict the result. [...] Read more.

The results of numerous studies show that the control of power grid modes is carried out mainly using a technical criterion. The economic criterion is taken into account through the use of complex and inaccurate models that do not accurately predict the result. The emergence of market relations in the energy sector makes power systems economic entities in terms of production and satisfaction of demand for electricity by various economic entities (industry, households, businesses, etc.). Under these conditions, electricity is a commodity with a corresponding price and quality indicators. This requires the application of the risk assessment methodology as an economic category in the activities of power systems as a business entity. The methodology of risk assessment in market conditions requires business entities to search for methods to minimize risk as a possibility of adverse events. Under these conditions, it becomes possible to make the best management decisions regarding the most important criterion that reflects the interests of business entities at a given time. However, the imperfection of the relevant methodology for risk assessment in the energy sector delays their application in the industry. At the same time, when making management decisions, three possible levels can be distinguished: decision-making in conditions of certainty, when the result is presented in a deterministic form and can be determined in advance; decision-making under conditions of risk, when the outcome cannot be determined in advance, but there is information on the probability of distribution of possible consequences; decision-making in conditions where the outcome is random and there is no information about the consequences of the decision. An analysis of scientific publications shows that some authors’ works are devoted to solving the issues of applying the theory and principles of risks in the energy sector, in which the problem is solved only at the first two levels. At the same time, the operation of energy facilities is characterized by a high level of uncertainty and incomplete information about the consequences of such decisions. Therefore, the development of a methodology for making management decisions in the energy sector based on the theory and practice of risks, taking into account the high level of uncertainty and incomplete information, is an urgent scientific task. Implementation of algorithms and programs for controlling the modes of power grids based on them can meet the requirements for reliable and high-quality energy supply to the most demanding consumers and create favorable conditions for their business. This work is devoted to the development of scientific and methodological foundations for determining the voltage risk in power system networks, taking into account the uncertain nature of the loads and its impact on consumers. Based on the results of the study, a mathematical model of the risk of voltage collapses in networks, an algorithm and a methodology for its calculation were proposed. Full article

(This article belongs to the Special Issue Managing Energy Sector Enterprises: Challenges, Methods and Research Trends: 2nd Edition)

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16 pages, 3414 KiB

Open AccessArticle

Efficiency Improvement in a Crude Oil Heating Furnace Based on Linear Regulation Control Strategies

by Francisco Jacas-Portuondo, Leonardo Peña-Pupo, Miguel R. Forgas-Brioso, Electo E. Silva-Lora, John A. Taborda-Giraldo and José R. Nuñez-Alvarez

Energies 2025, 18(7), 1578; https://doi.org/10.3390/en18071578 - 21 Mar 2025

This paper presents research results to improve energy efficiency in one of the crude oil heating furnaces at the “Hermanos Díaz” refinery in Santiago de Cuba, Cuba. It analyzes the main process’s variables and disturbances, and the multivariate dynamic behavior of the F-101 [...] Read more.

This paper presents research results to improve energy efficiency in one of the crude oil heating furnaces at the “Hermanos Díaz” refinery in Santiago de Cuba, Cuba. It analyzes the main process’s variables and disturbances, and the multivariate dynamic behavior of the F-101 furnace temperature is characterized to evaluate different control strategies. In addition, the design of a linear regulation control law was implemented as a way to solve the limitations of the existing control of the furnace, to control the plant for the first time with a multivariable approach, demonstrating superior performance by guaranteeing decoupling between the variables, decreasing the overruns by 6%, and increasing the response speed of the system by more than 5 min. The comparison with results obtained with other control strategies allowed us to determine the better performance of the furnace by increasing its energy efficiency, evidencing the economic and environmental impact and obtaining as benefits a better dynamic behavior by reducing fuel oil consumption by 5%, equivalent to 0.74 m³/day, which reduces the operating costs of the plant, the temperature of the gasses by 2%, emissions of CO₂ pollutant gas to the environment by between 3 and 5%, and increasing energy efficiency by 1.5%. Full article

(This article belongs to the Topic Recent Advances in Smart Grid and Energy Storage Applications)

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25 pages, 1227 KiB

Open AccessArticle

Collaborative Game Theory Between Microgrid Operators and Distribution System Operator Considering Multi-Faceted Uncertainties

by Shuai Wang, Xiaojing Ma, Yaling Yan, Tusongjiang Kari and Wei Zhang

Energies 2025, 18(7), 1577; https://doi.org/10.3390/en18071577 - 21 Mar 2025

In the vigorous development of the power system, to address the economic challenges of multi-microgrid systems, this paper proposes a Nash bargaining model for collaboration between microgrid operators (MGs) and a distribution system operator (DSO) under conditions of multiple uncertainties. Firstly, a model [...] Read more.

In the vigorous development of the power system, to address the economic challenges of multi-microgrid systems, this paper proposes a Nash bargaining model for collaboration between microgrid operators (MGs) and a distribution system operator (DSO) under conditions of multiple uncertainties. Firstly, a model for energy transactions between multiple complementary microgrid systems and a distribution system is established. Secondly, the chance-constrained method and robust optimization method are applied to model the multiple uncertainties in renewable energy generation and electricity trading prices. Moreover, using Nash bargaining theory, a cooperative operation model between MGs and a DSO is established, which is then transformed into two subproblems: cost minimization in cooperation and revenue maximization from power trading. To protect the privacy of each participant, a distributed solution approach using the alternating direction method of multipliers (ADMM) is applied to solve these subproblems. Finally, the simulation results indicate that the benefit values of all entities have improved after cooperative operation through the proposed model. Specifically, the benefit value of MG 1 is CNY 919,974.3, MG 2 is CNY 1,420,363.2, MG 3 is CNY 790,288.3, and the DSO is CNY 26,257.2. These results demonstrate that the proposed model has favorable economic performance. Full article

(This article belongs to the Special Issue Hybrid-Renewable Energy Systems in Microgrids)

25 pages, 1263 KiB

Open AccessArticle

Towards Net Zero in Poland: A Novel Approach to Power Grid Balance with Centralized Hydrogen Production Units

by Dariusz Bradło, Witold Żukowski, Jan Porzuczek, Małgorzata Olek and Gabriela Berkowicz-Płatek

Energies 2025, 18(7), 1576; https://doi.org/10.3390/en18071576 - 21 Mar 2025

The net zero emissions policy represents a crucial component of the global initiative to address climate change. The European Union has set a target of achieving net zero greenhouse gas emissions by 2050. This study assesses Poland’s feasibility of achieving net zero emissions. [...] Read more.

The net zero emissions policy represents a crucial component of the global initiative to address climate change. The European Union has set a target of achieving net zero greenhouse gas emissions by 2050. This study assesses Poland’s feasibility of achieving net zero emissions. Currently, Poland relies on fossil fuels for approximately 71% of its electricity generation, with electricity accounting for only approximately 16% of the country’s total final energy consumption. Accordingly, the transition to net zero carbon emissions will necessitate significant modifications to the energy system, particularly in the industrial, transport, and heating sectors. As this is a long-term process, this article demonstrates how the development of renewable energy sources will progressively necessitate the utilisation of electrolysers in line with the ongoing industrial transformation. A new framework for the energy system up to 2060 is presented, with transition phases in 2030, 2040, and 2050. This study demonstrates that it is feasible to attain a sustainable, zero-emission, and stable energy system despite reliance on uncontrolled and weather-dependent energy sources. Preparing the electricity grid to transmit almost three times the current amount represents a significant challenge. The resulting simulation capacities, comprising 64 GW of onshore wind, 33 GW of offshore wind, 136 GW of photovoltaic, 10 GW of nuclear, and 22 GW of electrolysers, enable a positive net energy balance to be achieved under the weather conditions observed between 2015 and 2023. To guarantee system stability, electrolysers must operate within a centralised framework, functioning as centrally controlled dispatchable load units. Full article

(This article belongs to the Special Issue Smart Grid and Energy Storage)

16 pages, 931 KiB

Open AccessReview

The Use of Jet A Aviation Fuel Blended with Biodiesel and Alcohols as a Sustainable Aviation Fuel: A Review

by Radu Mirea

Energies 2025, 18(7), 1575; https://doi.org/10.3390/en18071575 - 21 Mar 2025

The present paper is a review of the use of different types of blends of Jet A aviation fuel with biodiesel and alcohols, respectively, as sustainable aviation fuels (SAF). The scientific literature published from 2017 to 2024 was addressed and highlighted that the [...] Read more.

The present paper is a review of the use of different types of blends of Jet A aviation fuel with biodiesel and alcohols, respectively, as sustainable aviation fuels (SAF). The scientific literature published from 2017 to 2024 was addressed and highlighted that the use of Jet A fuel blended with alcohols and biodiesel has gained attention as a potential pathway to reducing aviation emissions and enhancing sustainability. Alcohol-blended Jet A fuels, such as ethanol and methanol mixtures, offer advantages including lower carbon monoxide (CO) and unburned hydrocarbon (HC) emissions due to their improved combustion efficiency. Similarly, biodiesel blends contribute to reduced particulate matter (PM) and CO emissions, while their oxygen content promotes cleaner combustion. Both types of blends have the potential to decrease the aviation sector’s carbon footprint and enhance fuel diversification. However, several gaps and limitations remain, including lower energy density leading to increased fuel consumption, material compatibility issues, increased nitrogen oxide (NO_x) emissions, and concerns over fuel stability. Further research is needed to optimize blend ratios, improve combustion control strategies, and ensure the safe and efficient integration of these alternative fuels in aviation. Full article

(This article belongs to the Special Issue Recent Advances in Biofuels Production and Usage: Challenges and Solutions)

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