Energies

15 pages, 8816 KiB

Open AccessArticle

Comparative Study of Different Machine Learning Models for Heat Transfer Performance Prediction of Evaporators in Modular Refrigerated Display Cabinets

by Kaifei Nong, Hua Zhang and Zhenzhen Liu

Energies 2024, 17(23), 6189; https://doi.org/10.3390/en17236189 (registering DOI) - 8 Dec 2024

Abstract

This study explores the potential of machine learning models to predict evaporator heat transfer performance in Modular Refrigerated Display Cases (MRDCs). Six experimental datasets from MRDC systems were analyzed to compare the efficacy of six machine learning models: Linear Regression, Decision Tree Regression, [...] Read more.

This study explores the potential of machine learning models to predict evaporator heat transfer performance in Modular Refrigerated Display Cases (MRDCs). Six experimental datasets from MRDC systems were analyzed to compare the efficacy of six machine learning models: Linear Regression, Decision Tree Regression, Support Vector Machines (SVMs), Feedforward Neural Networks (FNNs), Random Forest (RF), and Light Gradient Boosting Machine (LightGBM). The findings indicate that the ensemble tree-based models, LightGBM and RF, are particularly effective in predicting evaporator heat transfer performance. These models demonstrate high accuracy and robustness, effectively capturing the nonlinear relationship between the evaporator temperature and heat transfer coefficient. Moreover, LightGBM and RF exhibit notable stability and adaptability in scenarios of limited data availability and elevated noise levels. Their consistent predictive accuracy across different experimental conditions highlights their suitability for complex refrigeration systems. This research provides essential insights for optimizing MRDC evaporator performance, establishing a theoretical and data-driven foundation for energy-efficient enhancements and intelligent management within cold chain systems. Full article

(This article belongs to the Section J1: Heat and Mass Transfer)

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29 pages, 4069 KiB

Open AccessArticle

ML-Enabled Solar PV Electricity Generation Projection for a Large Academic Campus to Reduce Onsite CO₂ Emissions

by Sahar Zargarzadeh, Aditya Ramnarayan, Felipe de Castro and Michael Ohadi

Energies 2024, 17(23), 6188; https://doi.org/10.3390/en17236188 (registering DOI) - 8 Dec 2024

Abstract

Mitigating CO₂ emissions is essential to reduce climate change and its adverse effects on ecosystems. Photovoltaic electricity is 30 times less carbon-intensive than coal-based electricity, making solar PV an attractive option in reducing electricity demand from fossil-fuel-based sources. This study looks into utilizing [...] Read more.

Mitigating CO₂ emissions is essential to reduce climate change and its adverse effects on ecosystems. Photovoltaic electricity is 30 times less carbon-intensive than coal-based electricity, making solar PV an attractive option in reducing electricity demand from fossil-fuel-based sources. This study looks into utilizing solar PV electricity production on a large university campus in an effort to reduce CO₂ emissions. The study involved investigating 153 buildings on the campus, spanning nine years of data, from 2015 to 2023. The study comprised four key phases. In the first phase, PVWatts gathered data to predict PV-generated energy. This was the foundation for Phase II, where a novel tree-based ensemble learning model was developed to predict monthly PV-generated electricity. The SHAP (SHapley Additive exPlanations) technique was incorporated into the proposed framework to enhance model explainability. Phase III involved calculating historical CO₂ emissions based on past energy consumption data, providing a baseline for comparison. A meta-learning algorithm was implemented in Phase IV to project future CO₂ emissions post-solar PV installation. This comparison estimated a potential emissions reduction and assessed the university’s progress toward its net-zero emissions goals. The study’s findings suggest that solar PV implementation could reduce the campus’s CO₂ footprint by approximately 18% for the studied cluster of buildings, supporting sustainability and cleaner energy use on the campus. Full article

(This article belongs to the Special Issue Machine Learning in Renewable Energy Resource Assessment)

18 pages, 3995 KiB

Open AccessArticle

An Assessment of the Performance and Emissions of an Otto Power Generator Group Operating with Wet Ethanol at a High Volumetric Compression Ratio

by Vinícius Guerra Moreira, Sérgio de Morais Hanriot, Tales Nazareno, Bruno Eustáquio Pires Ferreira, Rafael Motter Juliatti, Hairton Júnior José da Silveira and Cristiana Brasil Maia

Energies 2024, 17(23), 6187; https://doi.org/10.3390/en17236187 (registering DOI) - 8 Dec 2024

Abstract

This work presents an experimental study of the performance and emissions of an internal combustion engine operating in the Otto cycle with a high volumetric compression ratio (17:1). The engine was initially fueled with the standard ethanol used in Brazil, with 7% distilled [...] Read more.

This work presents an experimental study of the performance and emissions of an internal combustion engine operating in the Otto cycle with a high volumetric compression ratio (17:1). The engine was initially fueled with the standard ethanol used in Brazil, with 7% distilled water (E93W07); we then studied the effects of using different ethanol-in-water mixtures, or ‘wet ethanol’, with 17%, 27%, 37%, and 47% distilled water concentrations. The tests were carried out with power loads of 5.0–25.0 kW at 5.0 kW intervals and with power loads of 27.5–35.0 kW at 2.5 kW intervals, whether by adding up the loads or by taking them away. The ignition timing was changed to evaluate each load imposed on the engine to avoid knocking. Specific fuel consumption (SFC), brake thermal efficiency (BTE), carbon dioxide emissions (CO₂), carbon monoxide (CO), nitrogen oxides (NO_x), and total hydrocarbon content (THC), as well as the internal pressure in the cylinder and the heat release rate, were measured, and the results are compared. The results show a reduction in CO and NO_x and an increase in THC emissions. However, there were no significant changes in CO₂ emissions when the distilled water percentage in ethanol increased. Regarding the brake thermal efficiency, it was observed that it remained approximately constant for all blends, with the same load being applied to the engine shaft, reaching a maximum value of 35%. The results obtained confirm the technical feasibility of operating an internal combustion engine in the Otto cycle with a high volumetric compression ratio using ethanol with up to 47% distilled water without significant loss of performance. Full article

(This article belongs to the Special Issue The Evolution and Future Prospects of Combustion Engines for Enhancing Energy Efficiency and Minimizing Environmental Impact)

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18 pages, 25928 KiB

Open AccessArticle

Advanced Control Algorithm for Shunt Active Power Filter: Enhancing Power Quality in Autonomous Grids

by Agata Bielecka

Energies 2024, 17(23), 6186; https://doi.org/10.3390/en17236186 (registering DOI) - 8 Dec 2024

Abstract

This study highlights the critical role of maintaining high power quality in autonomous grids, particularly in complex systems with significant non-linear loads, such as shipboard power systems. Power quality issues such as voltage harmonic distortion and imbalance can lead to serious malfunctions and [...] Read more.

This study highlights the critical role of maintaining high power quality in autonomous grids, particularly in complex systems with significant non-linear loads, such as shipboard power systems. Power quality issues such as voltage harmonic distortion and imbalance can lead to serious malfunctions and even accidents. This paper proposes an advanced predictive control algorithm with feedback from the supply current developed for a shunt active power filter. The presented control algorithm is characterized by high effectiveness in compensating supply current harmonics, imbalance, and reactive power, thereby improving power quality. This high performance in executing compensation tasks has been confirmed through experimental tests conducted in an autonomous grid powered by a diesel generator. The research results also include the system’s adaptability under varying load conditions, the impact of delays, and the converter’s non-linearities on the operation of the active power filter. Full article

(This article belongs to the Special Issue Power Electronics and Power Converters: Current Status and Future Prospects of Applications)

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32 pages, 1648 KiB

Open AccessArticle

Investments in Renewable Energy in Rural Communes: An Analysis of Regional Disparities in Poland

by Agnieszka Kozera, Aldona Standar, Joanna Stanisławska and Anna Rosa

Energies 2024, 17(23), 6185; https://doi.org/10.3390/en17236185 (registering DOI) - 8 Dec 2024

Abstract

Although energy transformation is a widely discussed topic, there is a dearth of research on the role of rural communes in implementing that concept in Poland, a country where rural areas account for more than 90% of the total landmass. Most research projects [...] Read more.

Although energy transformation is a widely discussed topic, there is a dearth of research on the role of rural communes in implementing that concept in Poland, a country where rural areas account for more than 90% of the total landmass. Most research projects are focused on larger local government units, such as cities, whereas rural communes’ role in the development of local energy policies and impact on the development of renewable energy sources (RESs) is often disregarded. Therefore, this study extends the existing literature resources with a view to bridging that gap by assessing rural communes’ investment activity in the context of the Polish energy transformation, with particular emphasis on regional differences in RES investments financed with Union funds. Therefore, the main purpose of this study is to assess the contribution of rural communes to the Polish energy transformation process, with a particular focus on regional differences in renewable energy investments financed with European Union funds in the successive seven-year financial perspectives 2007–2013 and 2014–2020. The study aimed to answer the following key research questions: how does the level of rural communes’ investment activities related to renewable energy development compare to that of other commune types? What are the regional differences in rural communes’ investment activities related to renewable energy? What are the main factors affecting rural communes’ investment activity in regions most involved in the development of renewable energies? The study relies on data from the Ministry of Development Funds and Regional Policy and from the Local Data Bank of the Central Statistical Office. The dataset was processed with the use of descriptive statistics methods and Ward’s method with a view to identifying regional patterns and conditions for the development of renewable energy investments. This study focuses on the investment activities of rural communes in Poland related to RESs financed with European Union funds. The empirical research results highlight rural municipalities’ crucial role in developing RES, emphasizing their high investment activity and significant regional differences. Municipalities from the eastern Polish provinces of Lublin and Podlasie have successfully secured EU funds for RES development. They have implemented numerous projects, primarily related to solar energy. Full article

(This article belongs to the Special Issue Energy Sources from Agriculture and Rural Areas II)

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16 pages, 2761 KiB

Open AccessArticle

Design of Energy Management Strategy for Integrated Energy System Including Multi-Component Electric–Thermal–Hydrogen Energy Storage

by Bo Peng, Yunguo Li, Hengyang Liu, Ping Kang, Yang Bai, Jianyong Zhao and Heng Nian

Energies 2024, 17(23), 6184; https://doi.org/10.3390/en17236184 (registering DOI) - 8 Dec 2024

Abstract

To address the challenges of multi-energy coupling decision-making caused by the complex interactions and significant conflicts of interest among multiple entities in integrated energy systems, an energy management strategy for integrated energy systems with electricity, heat, and hydrogen multi-energy storage is proposed. First, [...] Read more.

To address the challenges of multi-energy coupling decision-making caused by the complex interactions and significant conflicts of interest among multiple entities in integrated energy systems, an energy management strategy for integrated energy systems with electricity, heat, and hydrogen multi-energy storage is proposed. First, based on the coupling relationship of electricity, heat, and hydrogen multi-energy flows, the architecture of the integrated energy system is designed, and the mathematical model of the main components of the system is established. Second, evaluation indexes in three dimensions, including energy storage device life, load satisfaction rate, and new energy utilization rate, are designed to fully characterize the economy, stability, and environmental protection of the system during operation. Then, an improved radar chart model considering multi-evaluation index comprehensive optimization is established, and an adaptability function is constructed based on the sector area and perimeter. Combined with the operation requirements of the electric–thermal–hydrogen integrated energy system, constraint conditions are determined. Finally, the effectiveness and adaptability of the strategy are verified by examples. The proposed strategy can obtain the optimal decision instructions under different operation objectives by changing the weight of evaluation indexes, while avoiding the huge decision space and secondary optimization problems caused by multiple non-inferior solutions in conventional optimization, and has multi-scenario adaptability. Full article

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

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15 pages, 7814 KiB

Open AccessArticle

Fracture Propagation Laws and Influencing Factors in Coal Reservoirs of the Baode Block, Ordos Basin

by Qingfeng Zhang, Yongchen Li, Ziling Li, Yanbin Yao, Fengfeng Du, Zebin Wang, Zhihao Tang, Wen Zhang and Shutong Wang

Energies 2024, 17(23), 6183; https://doi.org/10.3390/en17236183 (registering DOI) - 8 Dec 2024

Abstract

The expansion of hydraulic fractures in coalbed methane (CBM) reservoirs is key to effective stimulation, making it essential to understand fracture propagation and its influencing factors for efficient resource development. Using petrological characteristics, logging data, microseismic monitoring, and fracturing reports from the Baode [...] Read more.

The expansion of hydraulic fractures in coalbed methane (CBM) reservoirs is key to effective stimulation, making it essential to understand fracture propagation and its influencing factors for efficient resource development. Using petrological characteristics, logging data, microseismic monitoring, and fracturing reports from the Baode Block on the eastern Ordos Basin, this study systematically investigates the geological and engineering factors influencing hydraulic fracture propagation. The real-time monitoring of fracture propagation in 12 fractured wells was conducted using microseismic monitoring techniques. The results indicated that the fracture orientations in the study area ranged from NE30° to NE60°, with fracture lengths varying between 136 and 226 m and fracture heights ranging from 8.5 to 25.3 m. Additionally, the fracturing curves in the study area can be classified into four types: stable, descending, fluctuating, and falling. Among these, the stable and descending types exhibit the most effective fracture propagation and are more likely to generate longer fractures. In undeformed–cataclastic coals and bright and semi-bright coals, long fractures are likely to form. When the Geological Strength Index (GSI) of the coal rock ranges between 60 and 70, fracture lengths generally exceed 200 m. When the coal macrolithotype index (S_m) is below 2, fracture lengths typically exceed 200 m. When the difference between the maximum and minimum horizontal principal stresses exceeds 5 MPa, fractures with length >180 m are formed, while fracture heights generally remain below 15 m. From an engineering perspective, for the study area, hydraulic fracturing measures with a preflush ratio of 20–30%, an average sand ratio of 13–15%, and a construction pressure between 15 MPa and 25 MPa are most favorable for coalbed methane production. Full article

(This article belongs to the Special Issue Research on Coalbed Methane and Coal-Measure Gas: Exploration, Exploitation, and Utilization)

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14 pages, 975 KiB

Open AccessArticle

Distributed Low-Carbon Energy Management of Urban Campus for Renewable Energy Consumption

by Kan Yu, Qiang Wei, Chuanzi Xu, Xinyu Xiang and Heyang Yu

Energies 2024, 17(23), 6182; https://doi.org/10.3390/en17236182 (registering DOI) - 8 Dec 2024

Abstract

In order to solve the mismatch between renewable energy and load in urban building microgrids, that is, the problem of renewable energy consumption in building microgrid clusters, while preserving the privacy of each user, this paper proposes a distributed low-carbon energy management method [...] Read more.

In order to solve the mismatch between renewable energy and load in urban building microgrids, that is, the problem of renewable energy consumption in building microgrid clusters, while preserving the privacy of each user, this paper proposes a distributed low-carbon energy management method for urban building microgrid clusters. First, a low-carbon energy management method for the urban building microgrid is proposed in order to coordinate the power sharing of various subjects to minimize the total economic cost, unleash the consumption potential of low-carbon building clusters for renewable energy, and reduce carbon emissions on the spatial and time scale. Second, an ADMM-based distributed optimal energy management method is proposed to meet user energy needs while preserving local privacy; this includes energy storage systems, renewable energy generation, and the loads within each urban building microgrid. Finally, simulation experiments are conducted based on actual data from a certain area in Hangzhou, China, and the results verify the effectiveness of the model. 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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18 pages, 1262 KiB

Open AccessReview

Analysis of Energy System Transformations in the European Union

by Agata Jaroń and Anna Borucka

Energies 2024, 17(23), 6181; https://doi.org/10.3390/en17236181 (registering DOI) - 7 Dec 2024

Abstract

Achieving climate neutrality has become an environmental goal for all European Union (EU) Member States. Thanks to numerous projects and subsidies, EU countries are able to achieve the goal of decarbonizing energy sources. The aim of the presented study is to assess the [...] Read more.

Achieving climate neutrality has become an environmental goal for all European Union (EU) Member States. Thanks to numerous projects and subsidies, EU countries are able to achieve the goal of decarbonizing energy sources. The aim of the presented study is to assess the validity of Member States’ actions to reduce CO₂ emissions based on data provided by Eurostat. The presented study combines, using regression, data on financial outlays dictated by environmental protection, the share of renewable energy, and total CO₂ emissions in individual Member States. This study has shown that, despite differences in the use of energy sources, Member States are able to achieve economic growth in symbiosis with the environment. Full article

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

20 pages, 11335 KiB

Open AccessArticle

Design and Analysis of Tubular Transverse Flux Permanent Magnet Linear Motor

by Guopeng Sun, Mei Zhao, Jianjun Li, Tong Yao and Huaqiang Zhang

Energies 2024, 17(23), 6180; https://doi.org/10.3390/en17236180 (registering DOI) - 7 Dec 2024

Abstract

The electrical load and the magnetic load of the transverse flux permanent magnet linear motor (TFPMLM) are decoupled from each other, which makes it easy to achieve modularization, and it has broad application prospects in the field of low speed and high thrust. [...] Read more.

The electrical load and the magnetic load of the transverse flux permanent magnet linear motor (TFPMLM) are decoupled from each other, which makes it easy to achieve modularization, and it has broad application prospects in the field of low speed and high thrust. Firstly, the topology structure of a cylindrical TFPMLM is proposed, and its working principle is introduced. Secondly, the basic electromagnetic performance of the motor is studied. Thirdly, the influence of the structural parameters on the flux linkage, back-EFM, and cogging force has been analyzed by the 3D finite element method (FEM). Then, the kriging agent model is constructed through the DOE experiment, and a set of size parameters with better performance are found by using a multi-objective genetic algorithm. Finally, the prototype and experimental setup have been developed. The calculated results and the measured results are in good agreement. Full article

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

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15 pages, 1323 KiB

Open AccessArticle

Effect of Corn Stover Ensiling on Methane Production and Carbon Dioxide Emissions

by Jacek Przybył, Dawid Wojcieszak and Tomasz Garbowski

Energies 2024, 17(23), 6179; https://doi.org/10.3390/en17236179 (registering DOI) - 7 Dec 2024

Abstract

The biogas and biomethane sectors are crucial for the European Union’s energy transition. One strategy for achieving the EU’s biogas and biomethane targets while reducing the use of agricultural land for energy feedstock production is to use alternative biomass streams. Such a stream [...] Read more.

The biogas and biomethane sectors are crucial for the European Union’s energy transition. One strategy for achieving the EU’s biogas and biomethane targets while reducing the use of agricultural land for energy feedstock production is to use alternative biomass streams. Such a stream includes agricultural residues and by-products. A good example is crop residues after harvesting corn for grain, which are available in large quantities. Due to the fact that they are lignocellulosic biomasses, they require pretreatment. The purpose of this study was to determine the effect of ensiling enhancers on the methane yield of corn stover silages. Corn stover, which was harvested using the same technology, was ensiled in the first variant with an ensiling enhancer preparation based on bacteria of the Lactobacillus plantarum strain (DSM 3676 and DSM 3677) and two strains of propionic acid bacteria (DSM 9676 and DSM 9677), in the second variant with a formulation whose active ingredients were sodium benzoate, propionic acid, and sodium propionite, and in the third with a formulation based on lactic acid bacteria of the strain Lactobacillus plantarum and Lactobacillus Buchneri. The fourth variant was the control; that is, the material was ensiled naturally without the ensiling enhancer preparation. The use of the ensiling enhancer, based on lactic acid bacteria of the Lactobacillus plantarum and Lactobacillus Buchneri strains, reduced carbon dioxide emissions per 1 GJ of silage energy potential in the biogas production process. Specifically, the unique contribution of this research lies in demonstrating the role of ensiling enhancers in improving methane yield and reducing carbon dioxide emissions. Full article

(This article belongs to the Collection Feature Papers in Energy, Environment and Well-Being)

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22 pages, 7417 KiB

Open AccessArticle

A Novel Approach of −80 °C Cascade Refrigeration System Using Non-Flammable Quaternary Refrigerants for Semiconductor Process Applications

by Su-Been Lee, Chang-Hyo Son and Joon-Hyuk Lee

Energies 2024, 17(23), 6178; https://doi.org/10.3390/en17236178 (registering DOI) - 7 Dec 2024

Abstract

Ultra-low temperature chillers have seen increasing demand with the advancement of semiconductor technology. Mixed refrigerant (MR) cascade refrigeration systems (CRSs) are widely utilized for their stability and high cooling performance at low temperatures. Extensive research has been conducted on optimizing MR, which has [...] Read more.

Ultra-low temperature chillers have seen increasing demand with the advancement of semiconductor technology. Mixed refrigerant (MR) cascade refrigeration systems (CRSs) are widely utilized for their stability and high cooling performance at low temperatures. Extensive research has been conducted on optimizing MR, which has a significant impact on CRS performance. However, most previous studies have either fixed the system pressure or used the refrigeration effect as the sole performance indicator. This did not account for the potential of achieving higher performance with an optimal MR composition at the same target temperature. In this study, a detailed parametric analysis was performed to investigate how the mass fractions of high-, mid-, and low boiling point refrigerants affect the coefficient of performance (COP) and exergy in ultra-low temperature CRSs without fixing the suction pressure. The analysis revealed that at the point of maximum COP, the refrigeration effect was relatively low, highlighting the limitations of using the refrigeration effect alone as a performance indicator. Additionally, COP was found to inversely correlate with total exergy destruction. As cascade temperature increases, COP tends to decrease, emphasizing the need for appropriate cascade temperature selection for MR CRS performance. This study introduces a novel approach to optimizing MR composition under various operating conditions, contributing to the advancement of ultra-low temperature CRSs. Full article

(This article belongs to the Section K: State-of-the-Art Energy Related Technologies)

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47 pages, 1820 KiB

Open AccessReview

Energy Utilization of Rapeseed Biomass in Europe: A Review of Current and Innovative Applications

by Tomasz Suchocki

Energies 2024, 17(23), 6177; https://doi.org/10.3390/en17236177 (registering DOI) - 7 Dec 2024

Abstract

Rapeseed (Brassica napus L.) biomass holds significant potential as a renewable energy resource in Europe due to its adaptability, high oil content, and role in biodiesel production. This review explores the energy applications of rapeseed biomass, examining its agronomic characteristics and environmental [...] Read more.

Rapeseed (Brassica napus L.) biomass holds significant potential as a renewable energy resource in Europe due to its adaptability, high oil content, and role in biodiesel production. This review explores the energy applications of rapeseed biomass, examining its agronomic characteristics and environmental benefits. A detailed analysis of extraction processes—pressing, solvent extraction, and refining—highlights methods to optimize oil yield and quality. Additionally, the review addresses the use of rapeseed oil in various biofuel applications, including its direct use and in blends with fuels like alcohols and hydrogen, analyzing performance and emissions outcomes. Rapeseed cake, a valuable by-product, is discussed for its dual role as animal feed and as a moderate biofuel alternative. Emissions data and combustion efficiency metrics provide insights into the feasibility of rapeseed oil as a fuel substitute. Overall, this review aims to underscore the contributions of rapeseed biomass to sustainable energy and to identify gaps in current research that can guide future innovations in biofuel production and agricultural sustainability in Europe. Research in rapeseed biomass focuses on optimizing extraction methods, improving combustion efficiency and emission control, exploring advanced uses for rapeseed cake, developing higher-yielding and resilient varieties, conducting lifecycle sustainability assessments, and investigating new biofuel blends and applications. Full article

(This article belongs to the Section A4: Bio-Energy)

31 pages, 2112 KiB

Open AccessArticle

Improving Energy Efficiency of School Buildings: A Case Study of Thermal Insulation and Window Replacement Using Cost-Benefit Analysis and Energy Simulations

by Dušan Ranđelović, Vladan Jovanović, Marko Ignjatović, Janusz Marchwiński, Ołeksij Kopyłow and Vuk Milošević

Energies 2024, 17(23), 6176; https://doi.org/10.3390/en17236176 (registering DOI) - 7 Dec 2024

Abstract

This study demonstrates the benefits of comprehensive school building (SB) energy efficiency (EE) improvements through building envelope renovations, lighting upgrades, and changes to cleaner heat sources. The parametric study in the building energy simulation software was used to check the application of various [...] Read more.

This study demonstrates the benefits of comprehensive school building (SB) energy efficiency (EE) improvements through building envelope renovations, lighting upgrades, and changes to cleaner heat sources. The parametric study in the building energy simulation software was used to check the application of various interventions on the energy consumption of existing SBs while reducing CO₂ emissions with the most profitable return on investment (ROI). The energy savings from window replacements did not correspond with expectations. However, other measures such as the wall, roof insulation, and lighting modernization improved EE by up to 152 kWh/m² and 41 kg/m² CO₂/m² annually. The study also points to a significant trade-off between district heating (which reduces CO₂ but has a slower ROI) and other heating solutions. The results suggest that climate-specific insulation thickness and glazing type needs are required, and optimal insulation strategies are shown to improve EE by 48–56% and CO₂ reductions of 45–56%. Lighting replacement and biogas boiler use were both impactful. The findings support the importance of sustainable practices, which should stimulate educational awareness and environmental responsibility. This research presents actionable insights for EE and sustainable development from within educational facilities. Full article

(This article belongs to the Special Issue Research Trends of Thermal Comfort and Energy Efficiency in Buildings)

18 pages, 5275 KiB

Open AccessArticle

Research on Junction Temperature Smooth Control of SiC MOSFET Based on Body Diode Conduction Loss Adjustment

by Junke Wu, Yunpeng Wei, Yuntao Wu, Zhou Wang, Xingyu Li and Xiangnan Wei

Energies 2024, 17(23), 6175; https://doi.org/10.3390/en17236175 (registering DOI) - 7 Dec 2024

Abstract

In a converter of actual working condition, the change in the current and voltage of the power device will cause the junction temperature to fluctuate greatly. This device is subjected to high thermal stress due to the change in the junction temperature. Therefore, [...] Read more.

In a converter of actual working condition, the change in the current and voltage of the power device will cause the junction temperature to fluctuate greatly. This device is subjected to high thermal stress due to the change in the junction temperature. Therefore, it is necessary to adopt junction temperature control to reduce or smooth the junction temperature fluctuation, so as to realize the junction temperature control and improve the reliability of the device. At present, the methods for the junction temperature control of power devices have certain limitations and there are few active thermal management methods proposed for SiC device characteristics. In this paper, a method for realizing the smooth control of the junction temperature of a SiC device based on the conduction loss adjustment of the body diode for the SiC device has been proposed, considering that the conduction loss of the body diode is greater than the conduction loss of the SiC MOSFET. The conduction time of SiC MOSFET body diode was adjusted. By adjusting the conduction loss of the SiC MOSFET device, the fluctuation range of the junction temperature of the SiC MOSFET device was controlled, the smooth control of the junction temperature of the SiC device was realized, and the thermal stress of the device was reduced. Full article

(This article belongs to the Special Issue Reliability of Power Electronics Devices and Converter Systems)

22 pages, 25521 KiB

Open AccessArticle

Contributon-Informed Approach to RPV Irradiation Study Using Hybrid Shielding Methodology

by Mario Matijević, Krešimir Trontl and Dubravko Pevec

Energies 2024, 17(23), 6174; https://doi.org/10.3390/en17236174 (registering DOI) - 7 Dec 2024

Abstract

An important aspect of pressurized water reactor (PWR) lifetime monitoring is supporting radiation shielding analyses which can quantify various in-core and out-core effects induced in reactor materials by varying neutron–gamma fields. A good understanding of such a radiation environment during normal and accidental [...] Read more.

An important aspect of pressurized water reactor (PWR) lifetime monitoring is supporting radiation shielding analyses which can quantify various in-core and out-core effects induced in reactor materials by varying neutron–gamma fields. A good understanding of such a radiation environment during normal and accidental operating conditions is required by plant regulators to ensure proper shielding of equipment and working personnel. The complex design of a typical PWR is posing a deep penetration shielding problem for which an elaborate simulation model is needed, not only in geometrical aspects but also in efficient computational algorithms for solving particle transport. This paper presents such a hybrid shielding approach of FW-CADIS for characterization of the reactor pressure vessel (RPV) irradiation using SCALE6.2.4 code package. A fairly detailed Monte Carlo model (MC) of typical reactor internals was developed to capture all important streaming paths of fast neutrons which will backscatter the biological shield and thus enhance RPV irradiation through the cavity region. Several spatial differencing and angular segmentation options of the discrete ordinates S_N flux solution were compared in connection to a S_N mesh size and were inspected by VisIt code. To optimize MC neutron transport toward the upper RPV head, which is a particularly problematic region for particle transport, a deterministic solution of discrete ordinates in forward/adjoint mode was convoluted in a so-called contributon flux, which proved to be useful for subsequent S_N mesh refinement and variance reduction (VR) parameters preparation. The pseudo-particle flux of contributons comes from spatial channel theory which can locate spatial regions important for contributing to a shielding response. Full article

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

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24 pages, 897 KiB

Open AccessArticle

Market Risk of Lithium Industry Chain—Evidence from Listed Companies

by Weicheng Kong, Jinhua Cheng and Jianzhong Xiao

Energies 2024, 17(23), 6173; https://doi.org/10.3390/en17236173 (registering DOI) - 7 Dec 2024

Abstract

Lithium, a crucial raw material for new energy vehicles, is experiencing significant market price fluctuations due to escalating geopolitical conflicts, periodic mismatches in supply and demand, and increased attention to lithium resources from countries around the world. These factors may adversely affect the [...] Read more.

Lithium, a crucial raw material for new energy vehicles, is experiencing significant market price fluctuations due to escalating geopolitical conflicts, periodic mismatches in supply and demand, and increased attention to lithium resources from countries around the world. These factors may adversely affect the development of the new energy vehicle industry. This paper adopts the TVP-VAR-DY model, which measures dynamic spillover effects by allowing for variance changes through the estimation of a stochastic Kalman filter, thereby measuring risk spillover among upstream and downstream firms in the lithium industry chain. We selected 16 listed companies and six regional financial markets as the research sample, with the sample period from 4 July 2018, to 30 June 2023. The main conclusions are as follows: Between 2018 and 2020, the overall risk spillover in the lithium industry chain demonstrated a declining trend, though it experienced a sudden surge in 2020 as a result of the COVID-19 pandemic. This increase was followed by a gradual decline as the global economy improved and market stability was restored, leading to a reduction in risk aversion. Regarding the reception of risk spillovers, upstream firms exhibited a generally consistent level of directional risk spillovers, whereas downstream firms experienced more significant fluctuations. Chinese firms exhibited a higher level of received risk spillovers compared to their international counterparts, with less variation in these spillovers. From the perspective of risk spillover effects, significant variations were observed between firms in both the upstream and downstream markets. Chinese firms exhibited a higher level of risk inflow than international firms, with more pronounced changes in risk spillovers. Upstream enterprises should enhance their market competitiveness to mitigate the adverse effects of economic uncertainty. Downstream enterprises can alleviate the rise in raw material costs resulting from market price fluctuations through strategic cooperation. Additionally, the government should increase the market supply of resources, which will contribute to the establishment of a more robust lithium industry chain system. Full article

(This article belongs to the Special Issue Industrial Chain, Supply Chain and Value Chain in the Energy Industry: Impacts and Challenges in the Green and Low-Carbon Transition)

18 pages, 854 KiB

Open AccessArticle

A Closed-Loop Economy in the Meat Industry for Generating Alternative Energy from Biogas Plants

by Elżbieta Jadwiga Szymańska, Robert Mroczek and Jadwiga Drożdż

Energies 2024, 17(23), 6172; https://doi.org/10.3390/en17236172 (registering DOI) - 7 Dec 2024

Abstract

This study deals with the concept of a closed-loop economy in the meat industry through the use of animal by-products in biogas plants for electricity generation processes. The purpose of the study was to identify the volume of by-products from the slaughter of [...] Read more.

This study deals with the concept of a closed-loop economy in the meat industry through the use of animal by-products in biogas plants for electricity generation processes. The purpose of the study was to identify the volume of by-products from the slaughter of cattle and pigs, how the by-products are managed, and the efficiency of their use in biogas plants for electricity production processes. The analyses used data from the Central Statistical Office, the Chief Veterinary Inspectorate, and information obtained from the Polish Agency for Enterprise Development. Studies from the literature on closed-loop economies and bioeconomies were also a valuable source of information. Based on case studies, this paper also presents examples of a closed-loop economy in meat companies. In the area of pork, poultry, and beef livestock production, the analysis covered the years 2004–2022, while in the area of the production and use of meat industry by-products, the data came from 2017–2022. The study shows that reducing the production of waste in the meat industry and the reuse and recycling of waste are important parts of a closed-loop economy. In meat companies, waste from slaughtering animals can be properly managed, either by processing it into animal feed or by using it in biogas plants to generate electricity or heat. Taking into account the number of by-products from cattle and pig slaughter in the country, biogas plants could produce approximately 95,232 MW of electricity per year, which constitutes approximately 4.3% of the energy intensity of the meat industry in Poland. Full article

(This article belongs to the Special Issue Circular Economy, Environmental and Energy Management)

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21 pages, 6958 KiB

Open AccessArticle

Comparative Assessments of At-Sea and Inland Low- and Medium-Pressure CO₂ Transport

by Ingeborg Treu Røe, Pauline Oeuvray, Marco Mazzotti and Simon Roussanaly

Energies 2024, 17(23), 6171; https://doi.org/10.3390/en17236171 (registering DOI) - 7 Dec 2024

Abstract

Developing cost-efficient systems for transporting CO2 is key to accelerating the deployment of carbon capture and storage. The present work explores the impact of reducing the pressure of tank-based inland and at-sea transport on their techno-economic performance. The study uses established techno-economic models [...] Read more.

Developing cost-efficient systems for transporting CO2 is key to accelerating the deployment of carbon capture and storage. The present work explores the impact of reducing the pressure of tank-based inland and at-sea transport on their techno-economic performance. The study uses established techno-economic models for CO2 transport, adjusted with the most up-to-date knowledge on the costs of low-pressure containment and transport. In particular, the impact of cargo tank material and design on the transport costs show that low-pressure cargo tank systems can be 50% less expensive than medium-pressure systems if materials with similar price and strength can be used. This results in reductions in transport costs as high as 30% for long distances. This is partly driven by the currently suggested size limitation on medium-pressure shipping that limits its economies of scale. If this limitation is alleviated, the cost advantage of low-pressure shipping compared to medium-pressure is more limited (10–20%) although it remains advantageous. The same scaling effects on capacity were not found for truck and barge inland transport, thus yielding 1–10% cost reductions of low-pressure transport relative to medium-pressure transport. These results imply that future systems may combine medium-pressure inland and low-pressure at-sea transport and that efficient solutions connecting the two must be investigated. Full article

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

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