Energies

20 pages, 51352 KiB

Open AccessArticle

A Novel Methodology for Assessing the Electricity Generation Potential of Biomass Residues: A Case Study in the State of Minas Gerais, Brazil

by Fernando Bruno Dovichi Filho, Electo Eduardo Silva Lora, Diego Mauricio Yepes Maya, José Carlos Escobar Palacio, Osvaldo Jose Venturini, Laura Vieira Maia de Sousa, Flavio Dias Mayer and Marcelo Risso Errera

Energies 2025, 18(9), 2321; https://doi.org/10.3390/en18092321 - 1 May 2025

Abstract

This study presents a methodology for assessing the technical and economic potential of electricity generation from biomass residues, using thermochemical conversion technologies. Applied in the state of Minas Gerais, Brazil, the analysis focuses on residues from corn, soybean, coffee, eucalyptus, and sugarcane. A [...] Read more.

This study presents a methodology for assessing the technical and economic potential of electricity generation from biomass residues, using thermochemical conversion technologies. Applied in the state of Minas Gerais, Brazil, the analysis focuses on residues from corn, soybean, coffee, eucalyptus, and sugarcane. A multi-criteria decision-making (MCDM) approach, integrated with GIS, was used to identify the most viable biomass sources and most suitable conversion technologies, namely the Rankine cycle, organic Rankine cycle, and gasification with internal combustion engines, based on Technological Readiness Levels (TRLs). Eucalyptus emerged as the most suitable residue due to its high energy density, while sugarcane residues were the most abundant. The economic feasibility analysis indicates levelized costs ranging from USD 0.10 to USD 0.24 per kWh, with the conventional Rankine cycle emerging as the most cost-effective option for plants with a capacity exceeding 5 MWe. The proposed methodology supports strategic bioenergy planning by integrating geospatial, technological, and economic factors. Full article

(This article belongs to the Special Issue Selected Papers from the 32nd European Biomass Conference and Exhibition (EUBCE 2024))

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21 pages, 259 KiB

Open AccessArticle

Embedding Party Organization Governance in Energy Management: Effects on Corporate Carbon Emissions in Chinese State-Owned Enterprises

by Shiquan Wang and Yu Liang

Energies 2025, 18(9), 2320; https://doi.org/10.3390/en18092320 - 1 May 2025

Abstract

Theoretical and practical ambiguities concerning the impact of Party organization governance on corporate carbon emissions in China are addressed in this study. Data from A-share-listed state-owned enterprises in Shanghai and Shenzhen (2016–2021) are analyzed to determine how Party organization governance influences corporate carbon [...] Read more.

Theoretical and practical ambiguities concerning the impact of Party organization governance on corporate carbon emissions in China are addressed in this study. Data from A-share-listed state-owned enterprises in Shanghai and Shenzhen (2016–2021) are analyzed to determine how Party organization governance influences corporate carbon emissions. Fixed-effects regression results indicate that Party organization governance significantly reduces emissions. Robustness is established via alternative variable measures, instrumental variable estimation, and the inclusion of supplementary controls. Notably, the effect weakens as privatization intensifies. Conversely, SOEs embedding high-quality Party building into articles of association or situated in regions rich in red cultural resources exhibit amplified emission reductions. The findings enhance comprehension of Party organization governance’s environmental role in SOEs and inform the design of low-carbon energy governance frameworks. Full article

(This article belongs to the Section B: Energy and Environment)

25 pages, 1807 KiB

Open AccessReview

Advances and Challenges in Biohydrogen Production by Photosynthetic Microorganisms

by Cecilia Faraloni, Giuseppe Torzillo, Francesco Balestra, Isabela Calegari Moia, Raffaella Margherita Zampieri, Natalia Jiménez-Conejo and Eleftherios Touloupakis

Energies 2025, 18(9), 2319; https://doi.org/10.3390/en18092319 - 1 May 2025

Abstract

Hydrogen (H₂) production by photosynthetic microorganisms is a viable option for renewable energy due to its sustainability and potential for widespread application. Green algae, cyanobacteria, and purple non-sulfur bacteria have shown great promise in bio-H₂ production. However, problems such as [...] Read more.

Hydrogen (H₂) production by photosynthetic microorganisms is a viable option for renewable energy due to its sustainability and potential for widespread application. Green algae, cyanobacteria, and purple non-sulfur bacteria have shown great promise in bio-H₂ production. However, problems such as low H₂ production rates and high H₂ production costs continue to hinder the commercial scalability of these systems. To overcome these obstacles, genetic engineering selection of robust strains capable of coping with variable environmental conditions, optimization of growth conditions, use of wastewater, and biotechnological approaches such as immobilization are carefully considered. The aim of this review is to provide a thorough overview of the methods and developments that can improve H₂ production and to highlight current difficulties and future directions for further studies. Full article

(This article belongs to the Collection Current State and New Trends in Green Hydrogen Energy)

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22 pages, 2131 KiB

Open AccessReview

A Review of Quantitative Characterization of Phase Interface Dynamics and Optimization of Heat Transfer Modeling in Direct Contact Heat Transfer

by Mingjian Wang, Jianxin Xu, Shibo Wang and Hua Wang

Energies 2025, 18(9), 2318; https://doi.org/10.3390/en18092318 - 1 May 2025

Abstract

Direct contact heat transfer as an efficient heat recovery method. It is used in the fields of waste heat recovery, nuclear engineering, desalination, and metallurgy. This study examined two key issues of the direct contact heat transfer process: difficulty in accurately characterizing the [...] Read more.

Direct contact heat transfer as an efficient heat recovery method. It is used in the fields of waste heat recovery, nuclear engineering, desalination, and metallurgy. This study examined two key issues of the direct contact heat transfer process: difficulty in accurately characterizing the dynamics of the flow field–phase interface; and difficulty in coupling the complex multiphysics fields involved in direct contact heat transfer. This paper systematically reviews the spatio-temporal evolution characteristics and quantitative characterization methods of bubble dynamics in direct contact heat transfer processes, with an in-depth discussion on theoretical modeling approaches and experimental validation strategies for coupled heat and mass transfer mechanisms within multiphase flow systems. An interesting phenomenon was found in this study. Many scholars have focused their research on optimizing the working conditions and structure of direct contact heat transfer in order to improve heat transfer efficiency. The non-equilibrium phenomenon between the two phases of direct contact heat transfer has not been thoroughly studied. The non-equilibrium phase transition model can deepen the understanding of the microscopic mechanism of interfacial energy exchange and phase transition dynamics in direct contact heat transfer by revealing the transient characteristics and non-equilibrium effects of heat and mass transfer at dynamic interfaces. Based on the findings above, three key directions are proposed to guide future research to inform the exploration of direct contact heat transfer mechanisms in future work: 1 dynamic analysis of multi-scale spatio-temporal coupling mechanisms, 2 accurate quantification of unsteady interfacial heat transfer processes, and 3 synergistic integration of intelligent optimization algorithms with experimental datasets. Full article

(This article belongs to the Special Issue Advanced Analysis of Heat Transfer and Energy Conversion 2024)

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29 pages, 9574 KiB

Open AccessReview

Bidirectional DC-DC Converter Topologies for Hybrid Energy Storage Systems in Electric Vehicles: A Comprehensive Review

by Yan Tong, Issam Salhi, Qin Wang, Gang Lu and Shengyu Wu

Energies 2025, 18(9), 2312; https://doi.org/10.3390/en18092312 - 1 May 2025

Abstract

Electric Vehicles (EV) significantly contribute to reducing carbon emissions and promoting sustainable transportation. Among EV technologies, hybrid energy storage systems (HESS), which combine fuel cells, power batteries, and supercapacitors, have been widely adopted to enhance energy density, power density, and system efficiency. Bidirectional [...] Read more.

Electric Vehicles (EV) significantly contribute to reducing carbon emissions and promoting sustainable transportation. Among EV technologies, hybrid energy storage systems (HESS), which combine fuel cells, power batteries, and supercapacitors, have been widely adopted to enhance energy density, power density, and system efficiency. Bidirectional DC-DC converters are pivotal in HESS, enabling efficient energy management, voltage matching, and bidirectional energy flow between storage devices and vehicle systems. This paper provides a comprehensive review of bidirectional DC-DC converter topologies for EV applications, which focuses on both non-isolated and isolated designs. Non-isolated topologies, such as Buck-Boost, Ćuk, and interleaved converters, are featured for their simplicity, efficiency, and compactness. Isolated topologies, such as dual active bridge (DAB) and push-pull converters, are featured for their high voltage gain and electrical isolation. An evaluation framework is proposed, incorporating key performance metrics such as voltage stress, current stress, power density, and switching frequency. The results highlight the strengths and limitations of various converter topologies, offering insights into their optimization for EV applications. Future research directions include integrating wide-bandgap devices, advanced control strategies, and novel topologies to address challenges such as wide voltage gain, high efficiency, and compact design. This work underscores the critical role of bidirectional DC-DC converters in advancing energy-efficient and sustainable EV technologies. Full article

(This article belongs to the Special Issue Innovations in Fuel Cell and Electrolyzer Technology: Enhancing Efficiency with Power Electronic Converters and Expanding Applications)

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22 pages, 525 KiB

Open AccessArticle

Thermodynamic Analysis of Nuclear Power Plants with External Steam Superheating

by Vladimir Kindra, Mikhail Ostrovsky, Igor Maksimov, Roman Zuikin and Nikolay Rogalev

Energies 2025, 18(9), 2317; https://doi.org/10.3390/en18092317 - 30 Apr 2025

Abstract

Increasing the efficiency and capacity of nuclear power units is a promising direction for the development of power generation systems. Unlike thermal power plants, nuclear power plants operate at relatively low temperatures of the steam working fluid. Due to this, the thermodynamic efficiency [...] Read more.

Increasing the efficiency and capacity of nuclear power units is a promising direction for the development of power generation systems. Unlike thermal power plants, nuclear power plants operate at relatively low temperatures of the steam working fluid. Due to this, the thermodynamic efficiency of such schemes remains relatively low today. The temperature of steam and the efficiency of nuclear power units can be increased by integrating external superheating of the working fluid into the schemes of steam turbine plants. This paper presents the results of a thermodynamic analysis of thermal schemes of NPPs integrated with hydrocarbon-fueled plants. Schemes with a remote combustion chamber, a boiler unit and a gas turbine plant are considered. It has been established that superheating fresh steam after the steam generator is an effective superheating solution due to the utilization of heat from the exhaust gases of the GTU using an afterburner. Furthermore, there is a partial replacement of high- and low-pressure heaters in the regeneration system, with gas heaters for condensate and steam superheating after the steam generator for water-cooled and liquid-metal reactor types. An increase in the net efficiency of the hybrid NPP is observed by 8.49 and 5.11%, respectively, while the net electric power increases by 93.3 and 76.7%. Full article

(This article belongs to the Section B4: Nuclear Energy)

26 pages, 5707 KiB

Open AccessArticle

Dynamic Response and Reliability Assessment of Power Transmission Towers Under Wind-Blown Sand Loads

by Jun Lu, Jin Li, Xiaoqian Ma, Weiguang Tian, Linfeng Zhang and Peng Zhang

Energies 2025, 18(9), 2316; https://doi.org/10.3390/en18092316 - 30 Apr 2025

Abstract

The global transition toward clean energy has driven the extensive deployment of overhead tower-lines in desserts, where such structures face unique challenges from wind–sand interactions. The current design standards often overlook these combined loads due to oversimplified collision models and inadequate computational frameworks. [...] Read more.

The global transition toward clean energy has driven the extensive deployment of overhead tower-lines in desserts, where such structures face unique challenges from wind–sand interactions. The current design standards often overlook these combined loads due to oversimplified collision models and inadequate computational frameworks. These gaps are bridged in the present study through the development of a refined impact force model grounded in Hertz contact theory, which captures transient collision mechanics and energy dissipation during sand–structure interactions. Validated against field data from northwest China, the model enables a comprehensive parametric analysis of wind speed (5–60 m/s), sand density (1000–3500 kg/m³), elastic modulus (5–100 GPa), and Poisson’s ratio (0.1–0.4). Our results show that peak impact forces increase by 66.7% (with sand density) and 148% (with elastic modulus), with higher wind speeds amplifying forces nonlinearly, reaching 8 N at 30 m/s. An increased elastic modulus shifts energy dissipation toward elastic rebound, reducing the penetration depth by 28%. The dynamic analysis of a 123.6 m transmission tower under wind–sand coupling loads demonstrated significant structural response amplifications; displacements and axial forces increased by 28% and 41%, respectively, compared to pure wind conditions. These findings reveal the importance of integrating coupling load effects into design codes, particularly for towers in sandstorm-prone regions. The proposed framework provides a robust basis for enhancing structural resilience, offering practical insights for revising safety standards and optimizing maintenance strategies in arid environments. Full article

21 pages, 1407 KiB

Open AccessArticle

Energy Adaptability Analysis Based on the Stall Fault of Solar Array Drive Assembly for Medium Earth Orbit Satellite

by Chenjie Kong, Huan Liu, Baojun Lin, XueLiang Wang, Qiang Zhang and Yabin Wang

Energies 2025, 18(9), 2315; https://doi.org/10.3390/en18092315 - 30 Apr 2025

Abstract

In response to the stalling fault of the solar array drive assembly (SADA) in an in-orbit MEO satellite, an analysis and research on the energy balance algorithm are conducted. This is performed under the continuous changes in the light period, shadow period, and [...] Read more.

In response to the stalling fault of the solar array drive assembly (SADA) in an in-orbit MEO satellite, an analysis and research on the energy balance algorithm are conducted. This is performed under the continuous changes in the light period, shadow period, and the incident angle of the solar panels. An output energy model of the solar panels is presented. It is proven that this model is a continuous function, and the optimal stalling angle for energy output is deduced. By simulating and calculating the energy output under different stalling angles and taking into account the on-orbit performance degradation of the solar cell array, the energy output curve within one orbital period is obtained, which provides support for the on-orbit operation and maintenance of the satellite. Moreover, on-orbit verification was carried out in the case of a stalling fault of the -Y-wing SADA of a certain MEO-orbiting satellite. Full article

30 pages, 9122 KiB

Open AccessArticle

Application of Machine Learning Techniques for Predicting Heating Coil Performance in Building Heating Ventilation and Air Conditioning Systems

by Adam Nassif, Pasidu Dharmasena and Nabil Nassif

Energies 2025, 18(9), 2314; https://doi.org/10.3390/en18092314 - 30 Apr 2025

Abstract

Heating systems in a building’s mechanical infrastructure account for a significant share of global building energy consumption, underscoring the need for improved efficiency. This study evaluates 31 predictive models—including neural networks, gradient boosting (XGBoost), bagging, and multiple linear regression (MLR) as a baseline—to [...] Read more.

Heating systems in a building’s mechanical infrastructure account for a significant share of global building energy consumption, underscoring the need for improved efficiency. This study evaluates 31 predictive models—including neural networks, gradient boosting (XGBoost), bagging, and multiple linear regression (MLR) as a baseline—to estimate heating-coil performance. Experiments were conducted on a water-based air-handling unit (AHU), and the dataset was cleaned to eliminate illogical and missing values before training and validation. Among the evaluated models, neural networks, gradient boosting, and bagging demonstrated superior accuracy across various error metrics. Bagging offered the best balance between outlier robustness and pattern recognition, while neural networks showed strong capability in capturing complex relationships. An input-importance analysis further identified key variables influencing model predictions. Future work should focus on refining these modeling techniques and expanding their application to other HVAC components to improve adaptability and efficiency. Full article

(This article belongs to the Special Issue Building Energy Performance Modelling and Simulation)

25 pages, 2540 KiB

Open AccessReview

Research Progress and Perspectives of the Reaction Kinetics of Fe-Based Oxygen Carriers in Chemical Looping Combustion

by Jiakun Mei, Shangkun Quan, Hairui Yang, Man Zhang, Tuo Zhou, Xi Yang, Mingyu Zhang, Tae-young Mun, Zhouhang Li, Ryang-Gyoon Kim, Xing Zhu, Hua Wang and Dongfang Li

Energies 2025, 18(9), 2313; https://doi.org/10.3390/en18092313 - 30 Apr 2025

Abstract

Chemical looping combustion (CLC), a promising technology employing oxygen carriers to realize cyclic oxygen transfer between reactors, represents a transformative approach to CO₂ capture with near-zero energy penalties. Among oxygen carriers, Fe-based materials have emerged as the predominant choice due to their [...] Read more.

Chemical looping combustion (CLC), a promising technology employing oxygen carriers to realize cyclic oxygen transfer between reactors, represents a transformative approach to CO₂ capture with near-zero energy penalties. Among oxygen carriers, Fe-based materials have emerged as the predominant choice due to their cost-effectiveness, environmental compatibility, and robust performance. The reaction kinetics of oxygen carriers are crucial for both material development and the rational design of CLC systems. This comprehensive review synthesizes experimental and theoretical advances in kinetic characterization of Fe-based oxygen carriers, encompassing both natural and synthetic materials, while different models corresponding to specific reaction stages and their intrinsic relationships with microstructural transformations are systematically investigated. The kinetic characteristics across various reactor types and experimental conditions are analyzed. The differences between fixed bed thermogravimetric analysis and fluidized bed analysis are revealed, emphasizing the notable impacts of attrition on the kinetic parameters in fluidized beds. Furthermore, the effects of temperature and gas concentration on kinetic parameters are profoundly examined. Additionally, the significant performance variation of oxygen carriers due to their interaction with ash is highlighted, and the necessity of a quantitative analysis on the competing effects of ash is emphasized, providing actionable guidelines for advancing CLC technology using kinetics-informed material design and operational parameter optimization. Full article

(This article belongs to the Section D1: Advanced Energy Materials)

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33 pages, 2437 KiB

Open AccessArticle

Technical Feasibility Analysis of Green Energy Storage Options and Hornsea Wind Farms

by Muhammad Anas Maqbool, Md Jahir Rizvi, Yeaw Chu Lee and Pablo Borja Rosales

Energies 2025, 18(9), 2311; https://doi.org/10.3390/en18092311 - 30 Apr 2025

Abstract

The global transition towards clean energy sources is becoming essential to reduce reliance on conventional fuels and mitigate carbon emissions. In the future, the clean energy storage landscape, green hydrogen, and green ammonia (powered by renewable energy sources) are emerging as key players. [...] Read more.

The global transition towards clean energy sources is becoming essential to reduce reliance on conventional fuels and mitigate carbon emissions. In the future, the clean energy storage landscape, green hydrogen, and green ammonia (powered by renewable energy sources) are emerging as key players. This study explores the prospectives and feasibility of producing and storing offshore green hydrogen and green ammonia. The potential power output of Hornsea one and Hornsea two winds farms in the United Kingdom was calculated using real wind data. The usable electricity from the Hornsea one wind farm was 5.83 TWh/year, and from the Hornsea two wind farm, it was 6.44 TWh/year, harnessed to three different scenarios for the production and storage of green ammonia and green hydrogen. Scenario 1 fulfil the requirement of green hydrogen storage for flexible ammonia production but consumes more energy for green hydrogen compression. Scenario 2 does not offer any hydrogen storage which is not favourable in terms of flexibility and market demand. Scenario 3 offers both, a direct routed supply of produced hydrogen for green ammonia synthesis and a storage facility for green hydrogen storage. Detailed mathematical calculations and sensitivity analysis was performed based on the total energy available to find out the energy storage capacity in terms of the mass of green hydrogen and green ammonia produced. Sensitivity analysis in the case of scenario 3 was conducted to determine the optimal percentage of green hydrogen going to the storage facility. Based on the cost evaluation of three different presented scenarios, the levelized cost of hydrogen (LCOH) is between USD 5.30 and 5.97/kg, and the levelized cost of ammonia (LCOA) is between USD 984.16 and USD 1197.11/tonne. These prices are lower compared to the current UK market. The study finds scenario 3 as the most appropriate way in terms of compression energy savings, flexibility for the production and storage capacity that depends upon the supply and demand of these green fuels in the market, and a feasible amount of green hydrogen storage. Full article

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

17 pages, 6128 KiB

Open AccessArticle

Beam Shape Control System with Cylindrical Lens Optics for Optical Wireless Power Transmission

by Kenta Moriyama, Kaoru Asaba and Tomoyuki Miyamoto

Energies 2025, 18(9), 2310; https://doi.org/10.3390/en18092310 - 30 Apr 2025

Abstract

Due to its narrow divergence, optical wireless power transmission (OWPT) is promising for long-distance transmission systems. In OWPT systems, matching the beam shape with the solar cell geometry is crucial for both efficiency and safety. When the light is incident at an oblique [...] Read more.

Due to its narrow divergence, optical wireless power transmission (OWPT) is promising for long-distance transmission systems. In OWPT systems, matching the beam shape with the solar cell geometry is crucial for both efficiency and safety. When the light is incident at an oblique angle, the beam is distorted in an axial direction, which requires appropriate beam shape control. In this study, a cylindrical lens system was designed to ensure uniform and effective light beam irradiation, even under oblique incidence conditions. A numerical model of the optical system was constructed, and it was experimentally confirmed that the beam shape could be controlled within 5% error over a transmission range of 1 m. The optical system was integrated with solar cell detection for consistent target recognition and beam irradiation, and its functionality was experimentally validated. The results are useful for expanding the application and infrastructure design in OWPT. Full article

(This article belongs to the Special Issue Energy, Electrical and Power Engineering: 4th Edition)

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19 pages, 2288 KiB

Open AccessArticle

The Impact of Meteorological Data on the Accuracy of Solar Electricity Generation Forecasting Using Neural Networks

by Yuriy Sayenko, Ryszard Pawelek, Tetiana Baranenko and Vadym Liubartsev

Energies 2025, 18(9), 2309; https://doi.org/10.3390/en18092309 - 30 Apr 2025

Abstract

The resolution of key tasks related to energy resource conservation and the enhancement of energy security is not possible without the widespread use of the electricity generated by renewable energy sources (RES), including, among others, photovoltaic (solar) power plants. A negative aspect of [...] Read more.

The resolution of key tasks related to energy resource conservation and the enhancement of energy security is not possible without the widespread use of the electricity generated by renewable energy sources (RES), including, among others, photovoltaic (solar) power plants. A negative aspect of connecting renewable energy sources to power grids is the challenge of forecasting their generation, which consequently makes it difficult to plan the stable operation of power systems with distributed generation. To improve the accuracy of forecasting electricity generation by solar power plants, this article proposes the use, in addition to meteorological parameters such as air temperature and wind speed, of a new indicator defined as the unit active power generation (P*). This indicator can be used in the development of mathematical models and methods to increase the energy efficiency of power systems utilizing renewable energy sources, particularly to enhance the accuracy of power generation forecasting processes using neural networks and machine learning. The article shows that the use of this indicator allows for increasing the accuracy of forecasting energy production by solar power plants. Full article

(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)

38 pages, 1334 KiB

Open AccessArticle

Research on Day-Ahead Optimal Scheduling of Wind–PV–Thermal–Pumped Storage Based on the Improved Multi-Objective Jellyfish Search Algorithm

by Yunfei Hu, Kefei Zhang, Sheng Liu and Zhong Wang

Energies 2025, 18(9), 2308; https://doi.org/10.3390/en18092308 - 30 Apr 2025

Abstract

As the share of renewable energy in modern power systems continues to grow, its inherent uncertainty and variability pose severe challenges to grid stability and the accuracy of traditional thermal power dispatch. To address this issue, this study fully exploits the fast response [...] Read more.

As the share of renewable energy in modern power systems continues to grow, its inherent uncertainty and variability pose severe challenges to grid stability and the accuracy of traditional thermal power dispatch. To address this issue, this study fully exploits the fast response and flexible operation of variable-speed pumped storage (VS-PS) by developing a day-ahead scheduling model for a wind–photovoltaic–thermal–VS-PS system. The optimization model aims to minimize system operating costs, carbon emissions, and thermal power output fluctuations, while maximizing the regulation flexibility of the VS-PS plant. It is assessed using the improved multi-objective jellyfish search (IMOJS) algorithm, and its effectiveness is demonstrated through comparison with a fixed-speed pumped storage (FS-PS) system. Simulation results show that the proposed model significantly outperforms the traditional FS-PS system: it increases renewable energy accommodation capacity by an average of 68.51%, reduces total operating costs by 14.13%, and lowers carbon emissions by 3.63%. Full article

(This article belongs to the Section B: Energy and Environment)

19 pages, 1097 KiB

Open AccessBrief Report

Conversion to Fourth-Generation District Heating (4GDH): Heat Accumulation Within Building Envelopes

by Stanislav Chicherin

Energies 2025, 18(9), 2307; https://doi.org/10.3390/en18092307 - 30 Apr 2025

Abstract

This study investigates improving district heating (DH) systems by analyzing the effects of low-temperature operation on network efficiency, heat losses, and indoor temperature stability. A mathematical model is developed to simulate building heat performance under different supply temperatures, substation connection types, and envelope [...] Read more.

This study investigates improving district heating (DH) systems by analyzing the effects of low-temperature operation on network efficiency, heat losses, and indoor temperature stability. A mathematical model is developed to simulate building heat performance under different supply temperatures, substation connection types, and envelope materials. The methodology involves detailed hourly heat load simulations and optimization techniques to assess the impact of temperature flexibility and heat accumulation within buildings. The results reveal that a 10 °C reduction in supply temperature leads to a heat loss decrease of up to 20%, significantly improving system efficiency. Moreover, buildings with higher thermal inertia and indirect substation connections exhibit better resilience to short-term temperature fluctuations, ensuring more stable indoor conditions. The analysis also demonstrates that optimizing temperature control can reduce operational costs by 19%, primarily by minimizing excessive heat supply and utilizing stored thermal energy effectively. Despite slight temperature fluctuations in extreme conditions, the system maintains indoor comfort levels within acceptable limits. This study concludes that transitioning to a lower-temperature DH system is feasible without compromising reliability, provided heat accumulation effects and supply flexibility are carefully managed. These findings offer a replicable approach for improving DH efficiency in networks with diverse building configurations. Full article

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

29 pages, 2910 KiB

Open AccessArticle

Enhanced Passive Thermal Management for Electric Vehicle Batteries Using a 3D Pulsating Heat Pipe

by Luca Cattani, Federico Sacchelli and Fabio Bozzoli

Energies 2025, 18(9), 2306; https://doi.org/10.3390/en18092306 - 30 Apr 2025

Abstract

This study experimentally analyzes the performance of a passive thermal management system using a three-dimensional (3D) pulsating heat pipe (PHP) designed for pouch cell batteries in electric vehicles. The term “3D” refers to the complex spatial arrangement of the PHP, which features multiple [...] Read more.

This study experimentally analyzes the performance of a passive thermal management system using a three-dimensional (3D) pulsating heat pipe (PHP) designed for pouch cell batteries in electric vehicles. The term “3D” refers to the complex spatial arrangement of the PHP, which features multiple interconnected loops arranged in three dimensions to maximize heat dissipation efficiency and improve temperature uniformity around the battery pack. Lithium-ion pouch cells are increasingly favored for compact and lightweight battery packs but managing their heat generation is crucial to maintaining efficiency and preventing failure. This research investigates the operational parameters of a 3D PHP by testing two working fluids (R134a and Opteon-SF33), three filling ratios (30%, 50%, and 80%), and various condenser conditions (natural and forced convection at 5 °C, 20 °C, and 35 °C). The effectiveness of the PHP was tested using simulated battery discharge cycles, with power inputs ranging from 5 to 200 W. The results show that the 3D PHP significantly improves battery thermal management. Additionally, Opteon-SF33, an environmentally friendly refrigerant, offers excellent heat transfer properties, making 3D PHP with this fluid a promising passive cooling solution for electric vehicle batteries. Full article

(This article belongs to the Special Issue Advancements and Future Prospects of Heat Exchangers in Thermal and Energy Management)

18 pages, 2894 KiB

Open AccessArticle

Orderly Charging and Discharging Strategy for Electric Vehicles with Integrated Consideration of User and Distribution Grid Benefits

by Yizhe Chen, Yifan Gao, Ruifeng Zhao, Jiangang Lu, Ming Li, Chengzhi Wei and Junhao Li

Energies 2025, 18(9), 2305; https://doi.org/10.3390/en18092305 - 30 Apr 2025

Abstract

With the rapid development of electric vehicles (EVs), vehicle-to-grid has become a common way to participate in grid regulation. However, in the traditional vehicle-to-grid strategy, the disorganized or coercive regulatory characteristics of EVs always affect the overall satisfaction of EV users and the [...] Read more.

With the rapid development of electric vehicles (EVs), vehicle-to-grid has become a common way to participate in grid regulation. However, in the traditional vehicle-to-grid strategy, the disorganized or coercive regulatory characteristics of EVs always affect the overall satisfaction of EV users and the safe and economic operation of the distribution network. It is challenging to balance the interests of road network subjects. For this reason, this paper proposes an orderly charging and discharging strategy for electric vehicles with integrated consideration of user and distribution grid benefits. First, a comprehensive EV user satisfaction model that considers the vehicle owner’s travel costs is established by considering the vehicle’s travel status and the road resistance characteristics of the road network. Further, the EV orderly charging and discharging model is established to optimize the operation cost of the distribution network, voltage deviation, and EV users’ comprehensive satisfaction, which takes into account the vehicle owner’s satisfaction and the stable operation of the distribution network. Finally, the proposed strategy is validated using the IEEE 33-node arithmetic example. The results show that the peak-to-valley load difference of the distribution network under the strategy of this paper is 29.52% lower than that under the EV non-participation regulation strategy. Compared with the EV non-participation strategy, it can effectively reduce the single-day operation cost of the system by 2.47%. Full article

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16 pages, 10843 KiB

Open AccessArticle

Automatic and Versatile Test Bench for Data Collection on Battery Cells

by Esteban Marsal, Nicolás Martínez, Alfredo Pérez Vega-Leal, Federico Barrero, Mohamad Hamdan and Manuel G. Satué

Energies 2025, 18(9), 2304; https://doi.org/10.3390/en18092304 - 30 Apr 2025

Abstract

Rechargeable batteries are a key component of sustainable future systems, as their performance directly affects energy efficiency, maintenance costs, and system reliability. Assessing performance requires evaluating parameters such as the state of health (SoH) of the battery, which necessitates developing a system capable [...] Read more.

Rechargeable batteries are a key component of sustainable future systems, as their performance directly affects energy efficiency, maintenance costs, and system reliability. Assessing performance requires evaluating parameters such as the state of health (SoH) of the battery, which necessitates developing a system capable of efficiently gathering large amounts of data. This article presents a safe, simple, versatile, and automated system designed to test and characterize various types of battery cells. The system is conceived as a practical tool capable of automatically collecting the required data for analysis, thus enabling the determination of the performance parameters of a battery cell. The proposed system incorporates an innovative approach based on the concatenation of charge/discharge data, allowing for a more reliable evaluation of battery performance. Experimental tests show the interest and performance behavior of the proposed system. Full article

(This article belongs to the Section D2: Electrochem: Batteries, Fuel Cells, Capacitors)

24 pages, 10026 KiB

Open AccessArticle

Design and Analysis of a Novel Ocean Current Two-Coupled Crossflow Turbine Energy Converter

by Shueei-Muh Lin, Wei-Le Huang, Didi Widya Utama and Yang-Yih Chen

Energies 2025, 18(9), 2303; https://doi.org/10.3390/en18092303 - 30 Apr 2025

Abstract

In this study, a novel ocean current energy converter is proposed. The energy converter is composed of two crossflow turbines. The two turbines rotate at the same speed but in opposite directions; therefore, the summation of the hydrodynamic torques applied to the two [...] Read more.

In this study, a novel ocean current energy converter is proposed. The energy converter is composed of two crossflow turbines. The two turbines rotate at the same speed but in opposite directions; therefore, the summation of the hydrodynamic torques applied to the two turbines is equal to zero, which can make the converter self-stabilizing. A channel is designed to guide a large amount of water flowing through the turbine, thereby increasing the incident velocity, power, and efficiency of the turbine. The guide vanes are positioned in front of the turbine to guide the ocean current, producing the optimal flow incident angle and thereby increasing the performance of the turbine. A novel empirical formula for determining the power and efficiency of the converter is derived. Moreover, a computational fluid dynamics (CFD) analysis of the energy converter is conducted using the commercial software Star CCM+ in the standard κ-ω turbulence model with wall functions. The accuracy of the empirical formula is verified by comparing the theoretical results with those obtained using the CFD method. Finally, the effects of several parameters on the performance of the energy converter are investigated. The optimal parameters are obtained as follows: (1) The optimal setting angles of vanes γ₁ = 78°,

γ_{2} = γ_{1} + 10 °

, and

γ_{3} = γ_{1} - 5 °

. (2) The optimal blade angle β = 44°. (3) The optimal rotating speed N = 2.6 (V_cur/1.6) rpm. (4) The optimal ratio of turbine center distance r_L₄ ≥ 2.50. (5) The optimal ratio of turbine shaft length is approximately 5.5 < (r_shaft = W_shaft/D_tur)_opt < 5.7. (6) The performance of each turbine with N_blade = 31 blades is significantly better than that with N_blade = 23 blades. Full article

(This article belongs to the Section F3: Power Electronics)

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