Energies

34 pages, 7941 KiB

Open AccessReview

Calcium Borohydride Ca(BH₄)₂: Fundamentals, Prediction and Probing for High-Capacity Energy Storage Applications, Organic Synthesis and Catalysis

by Cezar Comanescu

Energies 2023, 16(11), 4536; https://doi.org/10.3390/en16114536 - 5 Jun 2023

Cited by 2 | Viewed by 3640

Abstract

Calcium borohydride (Ca(BH₄)₂) is a complex hydride that has been less investigated compared to its lighter counterpart, magnesium borohydride. While offering slightly lower hydrogen storage capacity (11.5 wt% theoretical maximum, 9.6 wt% under actual dehydrogenation conditions), there are many [...] Read more.

Calcium borohydride (Ca(BH₄)₂) is a complex hydride that has been less investigated compared to its lighter counterpart, magnesium borohydride. While offering slightly lower hydrogen storage capacity (11.5 wt% theoretical maximum, 9.6 wt% under actual dehydrogenation conditions), there are many improvement avenues for maximizing the reversible hydrogen storage that have been explored recently, from DFT calculations and polymorph investigations to reactive hydride composites (RHCs) and catalytic and nanosizing effects. The stability of Ca(BH₄)₂, the possibility of regeneration from spent products, and the relatively mild dehydrogenation conditions make calcium borohydride an attractive compound for hydrogen storage purposes. The ionic conductivity enhancements brought about by the rich speciation of borohydride anions can extend the use of Ca(BH₄)₂ to battery applications, considering the abundance of Ca relative to alkali metal borohydrides typically used for this purpose. The current work aims to review the synthetic strategies, structural considerations of various polymorphs and adducts, and hydrogen storage capacity of composites based on calcium borohydrides and related complex hydrides (mixed anions, mixed cations, additives, catalysts, etc.). Additional applications related to batteries, organic and organometallic chemistry, and catalysis have been briefly described. Full article

(This article belongs to the Special Issue Metal Hydrides Hydrogen Storage, Thermal Management, and Applications)

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Graphical abstract

23 pages, 5770 KiB

Open AccessReview

Insights into Induction Heating Processes for Polymeric Materials: An Overview of the Mechanisms and Current Applications

by Alberto Mariani and Giulio Malucelli

Energies 2023, 16(11), 4535; https://doi.org/10.3390/en16114535 - 5 Jun 2023

Cited by 3 | Viewed by 2523

Abstract

In polymer systems, induction heating (IH) is the physical outcome that results from the exposure of selected polymer composites embedding electrically-conductive and/or ferromagnetic fillers to an alternating electromagnetic field (frequency range: from kHz to MHz). The interaction of the applied electromagnetic field with [...] Read more.

In polymer systems, induction heating (IH) is the physical outcome that results from the exposure of selected polymer composites embedding electrically-conductive and/or ferromagnetic fillers to an alternating electromagnetic field (frequency range: from kHz to MHz). The interaction of the applied electromagnetic field with the material accounts for the creation of magnetic polarization effects (i.e., magnetic hysteresis losses) and/or eddy currents (i.e., Joule losses, upon the formation of closed electrical loops), which, in turn, cause the heating up of the material itself. The heat involved can be exploited for different uses, ranging from the curing of thermosetting systems, the welding of thermoplastics, and the processing of temperature-sensitive materials (through selective IH) up to the activation of special effects in polymer systems (such as self-healing and shape-memory effects). This review aims at summarizing the current state-of-the-art of IH processes for polymers, providing readers with the current limitations and challenges, and further discussing some possible developments for the following years. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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18 pages, 7476 KiB

Open AccessArticle

A Compact High-Stability Nanosecond Pulse Test System Using Corona-Stabilized Switch and Coaxial Resistance Divider

by Jinru Sun, Qin Qing, Haoliang Liu, Xueling Yao, Zijiao Jiao and Yiheng Wu

Energies 2023, 16(11), 4534; https://doi.org/10.3390/en16114534 - 5 Jun 2023

Viewed by 1883

Abstract

Due to the lack of a standard nanosecond high-voltage pulse generator for sensor calibration, a high-stability nanosecond high-voltage pulse test system was developed in terms of circuit analysis, structural design, and performance test. By establishing the equivalent circuit model of the nanosecond pulse [...] Read more.

Due to the lack of a standard nanosecond high-voltage pulse generator for sensor calibration, a high-stability nanosecond high-voltage pulse test system was developed in terms of circuit analysis, structural design, and performance test. By establishing the equivalent circuit model of the nanosecond pulse generator, the circuit component parameters of the five-stage Marx loop and the one-stage compression steepening unit were simulated. The influence of the action performance of the steepening gap on the characteristics of output nanosecond pulse was analyzed. The nanosecond pulse test system was established through the structural design of the nanosecond pulse-generating circuit, the development of a high-performance corona-stabilized switch, and the measurement of a fast-response resistance divider made of metal oxide thin-film resistors. The nanosecond pulse test system has the capability to output a double exponential nanosecond pulse voltages in the amplitude range of 10–60 kV with a rise time of 2.3 ± 0.5 ns and a half-peak time of 23 ± 5 ns. In addition, the output pulse voltage has a high consistency and stability in the full amplitude range. The maximum relative standard deviation of the peak value is 1.517%, and the relative standard uncertainty is less than 5‰. Full article

(This article belongs to the Special Issue Advances in Pulsed Power Technologies)

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29 pages, 5022 KiB

Open AccessArticle

The Impact of Renewable Energy Consumption and Economic Growth on Environmental Quality in Africa: A Threshold Regression Analysis

by Abdullahi Muazu, Qian Yu and Mona Alariqi

Energies 2023, 16(11), 4533; https://doi.org/10.3390/en16114533 - 5 Jun 2023

Cited by 5 | Viewed by 2524

Abstract

Nonrenewable energy makes up a sizeable portion of Africa’s gross domestic product. The continent heavily relies on nonrenewable energy sources, such as gasoline, for industrial and commercial uses, which helps it expand and develop, especially in oil-producing nations. Incorporating nonrenewable energies when analyzing [...] Read more.

Nonrenewable energy makes up a sizeable portion of Africa’s gross domestic product. The continent heavily relies on nonrenewable energy sources, such as gasoline, for industrial and commercial uses, which helps it expand and develop, especially in oil-producing nations. Incorporating nonrenewable energies when analyzing the relative effects of renewable energy consumption and economic growth on environmental quality is paramount. The transition to renewable energy has been identified as a contributing factor in clean energy and sustainable development, but the consumption of renewable energy in Africa is negligible. This study employed panel threshold regression and covered data from 1990 to 2019, and examined the non-linear relationship between renewable energy consumption, economic growth, and environmental quality. According to the study’s findings, the consumption of renewable energy has a nonlinearly negative relationship with carbon emission proxied environmental quality. The relationship between environmental quality and economic growth was also shown to be nonlinearly positive, pointing to the dominance of nonrenewable resources in the African industry. The report recommends an effective policy for boosting the use of renewable energy sources in order to support clean energy and sustainable development. Full article

(This article belongs to the Section C: Energy Economics and Policy)

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17 pages, 5626 KiB

Open AccessFeature PaperArticle

A Linear Quadratic Integral Controller for PV-Module Voltage Regulation for the Purpose of Enhancing the Classical Incremental Conductance Algorithm

by Noureddine Bouarroudj, Yehya Houam, Abdelhamid Djari, Vicente Feliu-Batlle, Abdelkader Lakhdari and Boualam Benlahbib

Energies 2023, 16(11), 4532; https://doi.org/10.3390/en16114532 - 5 Jun 2023

Cited by 1 | Viewed by 1445

Abstract

As a result of the exhaustion of fossil energy sources and the corresponding increase of their negative environmental impact, recent research has intensively focused on regions of alternative energy resources and, especially, on solar energy. Slow tracking of the maximum power point (MPP) [...] Read more.

As a result of the exhaustion of fossil energy sources and the corresponding increase of their negative environmental impact, recent research has intensively focused on regions of alternative energy resources and, especially, on solar energy. Slow tracking of the maximum power point (MPP) and fluctuations around the MPP reduce the efficiency of photovoltaic power generation systems (PV). This study offers a novel design for the MPPT controller, which we refer to as the “hybrid IC-LQI approach”, which combines the incremental conductance (IC) technique and the linear quadratic integral (LQI) controller based on the boost converter’s small signal model. We conduct a comparative study of the proposed hybrid IC-LQI, and the classical one-stage IC technique in order to show the effectiveness of our proposal under three different scenarios of weather conditions and load. According to simulation findings, the proposed hybrid IC-LQI approach has a high tracking efficiency of up to 98.92%, owing to faster tracking of MPP with very large reduction of oscillations. On the other hand, the IC technique provides less efficiency, up to 96.1%, showing very slow tracking and high oscillations. The presented analysis of the results confirms the superior performance of the developed hybrid IC-LQI technique to the classical IC technique. Full article

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

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12 pages, 3256 KiB

Open AccessArticle

Partial Photoluminescence Imaging for Inspection of Photovoltaic Cells: Artificial LED Excitation and Sunlight Excitation

by Alberto Redondo Plaza, Victor Ndeti Ngungu, Sara Gallardo Saavedra, José Ignacio Morales Aragonés, Víctor Alonso Gómez, Lilian Johanna Obregón and Luis Hernández Callejo

Energies 2023, 16(11), 4531; https://doi.org/10.3390/en16114531 - 5 Jun 2023

Cited by 2 | Viewed by 2213

Abstract

Photovoltaic power is a crucial renewable energy source that has the potential to enhance a city’s sustainability. However, in order to identify the various issues that may occur during the lifespan of a photovoltaic module, solar module inspection techniques are crucial. One valuable [...] Read more.

Photovoltaic power is a crucial renewable energy source that has the potential to enhance a city’s sustainability. However, in order to identify the various issues that may occur during the lifespan of a photovoltaic module, solar module inspection techniques are crucial. One valuable technique that is commonly used is luminescence, which captures silicon emissions. This article focuses on a specific luminescence technique called partial photoluminescence. This technique involves illuminating a specific portion of the solar cell surface and recording the luminescence emission generated in the remaining area. This method has been trialed in a laboratory environment, utilizing infrared LEDs as the excitation source. An analysis of the main parameters that affect the technique is provided, where pictures have been taken under varying exposure times ranging from 50 ms to 400 ms, irradiance levels ranging from 200 W/m² to 1000 W/m², and a percentage of illuminated cells ranging from 10% to 40%. Furthermore, the experimental device has been modified to generate images utilizing sunlight as the excitation source. Several pictures of damaged cells were taken under an irradiance range of 340 W/m² to 470 W/m². The quality of the partial photoluminescence images is comparable to conventional electroluminescence images, but longer exposure times are required. Full article

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

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19 pages, 943 KiB

Open AccessArticle

Proactive Frequency Stability Scheme: A Distributed Framework Based on Particle Filters and Synchrophasors

by Gian Paramo and Arturo Bretas

Energies 2023, 16(11), 4530; https://doi.org/10.3390/en16114530 - 5 Jun 2023

Cited by 3 | Viewed by 1341

Abstract

The reactive nature of traditional under-frequency load shedding schemes can lead to delayed response and unnecessary loss of load. This work presents a proactive framework for power system frequency stability. Bayesian filters and synchrophasors are leveraged to produce predictions after disturbances are detected. [...] Read more.

The reactive nature of traditional under-frequency load shedding schemes can lead to delayed response and unnecessary loss of load. This work presents a proactive framework for power system frequency stability. Bayesian filters and synchrophasors are leveraged to produce predictions after disturbances are detected. By being able to estimate the future state of frequency corrective actions can be taken before the system reaches a critical condition. This proactive approach makes it possible to optimize the response to a disturbance, which results in a decrease in the amount of compensation utilized. The framework is tested via Matlab simulations based on Kundur’s Two-Area System, and the IEEE 14-Bus System. Performance metrics are provided and evaluated against other contemporary solutions found in literature. During testing this framework outperformed other solutions by drastically reducing the amount of load dropped during compensation. Full article

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23 pages, 1027 KiB

Open AccessArticle

The Impact of Green Innovation on Carbon Emissions: Evidence from the Construction Sector in China

by Xinping Li, Qiongxia Qin and Yongliang Yang

Energies 2023, 16(11), 4529; https://doi.org/10.3390/en16114529 - 5 Jun 2023

Cited by 8 | Viewed by 2253

Abstract

Green innovation has been identified as a viable strategy to mitigate the tension between industrial change and pollutant emissions. Relevant research should focus more on the impact of eco-friendly innovations on carbon emissions. Consequently, using a panel data set that covers 30 Chinese [...] Read more.

Green innovation has been identified as a viable strategy to mitigate the tension between industrial change and pollutant emissions. Relevant research should focus more on the impact of eco-friendly innovations on carbon emissions. Consequently, using a panel data set that covers 30 Chinese provinces from 2005 to 2020, we examine whether there is a carbon-abatement effect of green innovation in the construction sector. According to the findings of a two-way fixed-effects model, green innovation substantially positively influences reduction in dioxide emissions in the Chinese construction industry. The results of a panel threshold model show a significant non-linear relationship between green innovation and carbon emissions when the environmental regulation intensity is used as the threshold variable. Furthermore, we discovered that green innovation cuts carbon emissions considerably through environmental regulation. Finally, the impact of abatement varies significantly between regions, innovation elements, and types of development. Full article

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

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43 pages, 21304 KiB

Open AccessReview

Sustainable Development of Operational Infrastructure for Electric Vehicles: A Case Study for Poland

by Adrian Chmielewski, Piotr Piórkowski, Jakub Możaryn and Stepan Ozana

Energies 2023, 16(11), 4528; https://doi.org/10.3390/en16114528 - 5 Jun 2023

Cited by 2 | Viewed by 4044

Abstract

This article overviews Poland’s current electric vehicle infrastructure development. It discusses market segmentation and the analysis of charging standards, connectors, and types of charging. The paper focuses on Poland’s charging infrastructure, including costs and charging times for popular electric vehicle models in 2022. [...] Read more.

This article overviews Poland’s current electric vehicle infrastructure development. It discusses market segmentation and the analysis of charging standards, connectors, and types of charging. The paper focuses on Poland’s charging infrastructure, including costs and charging times for popular electric vehicle models in 2022. It highlights the challenges faced by charging operators and the barriers to infrastructure development. The article also presents the outlook for the electric vehicle market in Poland until 2025 and 2030. Furthermore, it examines private charger development, particularly in prosumer households with renewable energy sources. The implementation of smart charging and the potential for vehicle-to-grid technology in Poland are addressed. Lastly, a comparative analysis of incentives for electric vehicle users in Poland and Norway is discussed in the context of achieving 100% zero-emission vehicle sales by 31 December 2035, in Poland. Full article

(This article belongs to the Special Issue Power Electronic Applications to All-Electric and Hybrid Transportation Systems, Renewable Energy Sources, Energy Harvesters and Energy Saving)

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24 pages, 10466 KiB

Open AccessArticle

Thermal Performance Analysis of Composite Phase Change Material of Myristic Acid-Expanded Graphite in Spherical Thermal Energy Storage Unit

by Ji Li, Weiqing Wang, Yimin Deng, Long Gao, Junchao Bai, Lei Xu, Jun Chen and Zhi Yuan

Energies 2023, 16(11), 4527; https://doi.org/10.3390/en16114527 - 5 Jun 2023

Cited by 2 | Viewed by 1303

Abstract

In order to improve energy storage efficiency and promote the early achievement of global carbon neutrality goals, this paper proposes a spherical thermal storage unit filled with a composite phase change material (CPCM) comprising myristic acid (MA) and expanded graphite (EG). The effects [...] Read more.

In order to improve energy storage efficiency and promote the early achievement of global carbon neutrality goals, this paper proposes a spherical thermal storage unit filled with a composite phase change material (CPCM) comprising myristic acid (MA) and expanded graphite (EG). The effects of EG content and Stefan number (Ste) on the melting performance were investigated through a combination of experiments and numerical simulations. The results show that an increase in EG content (especially for ≥4 wt.% EG) leads to a temperature profile that assumes a concentric ring shape, while the melting rate increases with an increase in both the EG mass fraction and the Ste number. Compared to pure MA, the time required to complete melting was reduced by 82.2%, 85.6%, and 88.0% at EG contents of 4 wt.%, 5 wt.%, and 6 wt.%, respectively. Notably, the Ste value has a greater effect on melting when the EG content is ≤3 wt.%. The optimal EG content in the spherical cell was determined to be 4 wt.%, and a dimensionless analysis established a general correlation between the liquid mass fraction and the Fo, Ste, and Gr numbers. Full article

(This article belongs to the Special Issue Phase Change Materials: The Ideal Solution for Thermal Management)

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19 pages, 4113 KiB

Open AccessArticle

Monitoring and Analysis of the Operation Performance of Vertical Centrifugal Variable Frequency Pump in Water Supply System

by Jianyong Hu, Chaohao Wang, Chengju Shan and Yunhui Guo

Energies 2023, 16(11), 4526; https://doi.org/10.3390/en16114526 - 5 Jun 2023

Cited by 4 | Viewed by 1446

Abstract

The stable operation of a variable frequency pump is of great importance to the management of a water supply project. Analyzing the operation performance based on monitoring data is necessary for maintaining the stable operation of a variable frequency pump. Several sensors are [...] Read more.

The stable operation of a variable frequency pump is of great importance to the management of a water supply project. Analyzing the operation performance based on monitoring data is necessary for maintaining the stable operation of a variable frequency pump. Several sensors are installed at six monitoring points on the pump to collect signals including vibration velocity, vibration acceleration and vibration displacement. Monitoring signals are preprocessed by smoothing, adjusting waveform trend and filtering on the basis of Fast Fourier Transform (FFT). Then, the vibration features are extracted by power spectrum analysis and cepstrum analysis methods. According to the extracted features, the vibration law and actual operation performance of a variable frequency pump under different operating conditions are analyzed. Results indicate that the vibration amplitude of the pump varies sharply under the operating conditions of [15 Hz, 20 Hz] and [30 Hz, 35 Hz]. The operating condition of [0 Hz, 15 Hz] is the restricted operating area of the pump. The vibration and noise continue increasing under the operating conditions of [35 Hz, 50 Hz] and reach the maximum values at 50 Hz. Therefore, the optimal operating is within the range of [20 Hz, 30 Hz]. Finally, by analyzing the critical values of the operating conditions, the fault diagnosis and the evaluation of the operating status are conducted. Full article

(This article belongs to the Special Issue Advanced Modeling and Control of Hydropower Generation Systems)

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17 pages, 4265 KiB

Open AccessReview

Topology and Control of Fuel Cell Generation Converters

by Jinghua Zhou, Qi Zhang and Jin Li

Energies 2023, 16(11), 4525; https://doi.org/10.3390/en16114525 - 5 Jun 2023

Cited by 3 | Viewed by 2309

Abstract

Fuel cell power generation is one of the important ways of utilizing hydrogen energy, which has good prospects for development. However, fuel cell volt-ampere characteristics are nonlinear, the output voltage is low and the fluctuation range is large, and a power electronic converter [...] Read more.

Fuel cell power generation is one of the important ways of utilizing hydrogen energy, which has good prospects for development. However, fuel cell volt-ampere characteristics are nonlinear, the output voltage is low and the fluctuation range is large, and a power electronic converter matching its characteristics is required to achieve efficient and stable work. Based on the analysis of the fuel cell’s characteristic mechanism, maximum power point tracking algorithm, fuel cell converter characteristics, application and converter control strategy, the paper summarizes the general principles of the topology of fuel cell converters. In addition, based on the development status of new energy, hydrogen energy is organically combined with other new energy sources, and the concept of 100% absorption system of new energy with green hydrogen as the main body is proposed to provide a reference for the development of hydrogen energy. Full article

(This article belongs to the Special Issue Advanced Research on Fuel Cells and Hydrogen Energy Conversion)

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16 pages, 1167 KiB

Open AccessArticle

Computation of Electric and Magnetic Fields Generated by Cloud-to-Cloud Lightning Channels

by Carlo Petrarca, Marco Balato, Luigi Verolino, Amedeo Andreotti and Dario Assante

Energies 2023, 16(11), 4524; https://doi.org/10.3390/en16114524 - 5 Jun 2023

Viewed by 1216

Abstract

The paper presents analytical formulas for computation in the time domain of electromagnetic (EM) fields generated by tortuous cloud-to-cloud (CC) lightning channels over a perfectly conducting ground. For the first time, the study was not limited to a horizontal lightning path [...] Read more.

The paper presents analytical formulas for computation in the time domain of electromagnetic (EM) fields generated by tortuous cloud-to-cloud (CC) lightning channels over a perfectly conducting ground. For the first time, the study was not limited to a horizontal lightning path but was extended to take into account the natural, tortuous geometry of the lightning channel. After the calculation of the step response, a convolution integration was applied for the computation of the fields generated by an arbitrary current source. The produced electric and magnetic fields were then compared with the fields generated by a horizontal channel. The method can be of primary importance to evaluating the hazards for electric and electronic systems of flying aircraft, estimating the voltages induced on overhead transmission lines by CC lightning, and, in general, evaluating the induced effects on sensitive electric and electronic components. Moreover, it may represent a simple, robust, and time-saving tool for estimating important physical parameters that characterize lightning phenomena. Full article

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

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17 pages, 8530 KiB

Open AccessArticle

Carbonate Concretions in Triassic Yanchang Formation (Ordos Basin, China) as Evidence of Hydrothermal Activity

by Mengsi Sun, Congjun Feng and Chiyang Liu

Energies 2023, 16(11), 4523; https://doi.org/10.3390/en16114523 - 5 Jun 2023

Cited by 1 | Viewed by 1494

Abstract

The discovery of concretions of Chang 7 shale formations in the Ordos basin has increased interest in the exploration of lacustrine carbonate genesis in these basins. In this paper, these concretions were sampled and used in major, trace, and isotopic geochemistry tests. We [...] Read more.

The discovery of concretions of Chang 7 shale formations in the Ordos basin has increased interest in the exploration of lacustrine carbonate genesis in these basins. In this paper, these concretions were sampled and used in major, trace, and isotopic geochemistry tests. We used a microscope to investigate these concretions, and the results showed that the concretions consisted of carbonate rocks, the calcite was hydrothermal calcite, and obvious hydrothermal activity was present in the Yanchang period. We used seismic data to interpret the faults, and we determined that tectonic activity was relatively frequent in the middle–late Triassic period and that the faults were channels for hydrothermal upwelling. During the middle–late Triassic period, tectonic movement of the basin occurred, and synsedimentary faults developed in the Yanchang Formation. As deep hydrothermal gushers rose through faults and fractures, they carried particles upward through the deep limestone strata. When the hydrothermal gushers reached the lake bottom, the particles precipitated and eventually formed concretions via diagenesis. Full article

(This article belongs to the Special Issue Sedimentary Organic Matter in Shale Oil/Gas Systems)

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17 pages, 13466 KiB

Open AccessReview

Environmental and Technological Problems for Natural Gas Production in Permafrost Regions

by Vladimir Yakushev

Energies 2023, 16(11), 4522; https://doi.org/10.3390/en16114522 - 5 Jun 2023

Cited by 5 | Viewed by 1327

Abstract

Russia has unique technical and technological experience of gas field development in permafrost regions. According to this experience, different environmental and geocryological conditions require different technical solutions. Such problems as considerable subzero temperatures in geologic sections, great ice saturation of subsurface sediments, and [...] Read more.

Russia has unique technical and technological experience of gas field development in permafrost regions. According to this experience, different environmental and geocryological conditions require different technical solutions. Such problems as considerable subzero temperatures in geologic sections, great ice saturation of subsurface sediments, and gas and gas hydrate accumulations inside permafrost and immediately below it cause a series of dangerous consequences when gas production wells are in operation. These include back freezing, breaking well casings, well site subsidence when in production; movement and deformation of the wellhead caused by thawing of the rock massif around the well column when in operation; sudden and strong gas blowouts during well drilling, completion, and operation. To prevent possible accidents, different technical and technological solutions are applied: zoning of the field area according to the degree of complexity of geocryological conditions and the correction of future gas well cluster locations to avoid zones with extremely complex conditions; preliminary degassing of permafrost zones by shallow slim wells in places of future production well clusters; mechanical support of unstable production wells; installation of passive and active heat-isolation systems to the well construction and inside ground around wellheads. Key messages received during the development of gas fields at complex geocryological conditions are (consistently): preliminary careful geological engineering surveys and zoning of the field area, well clusters placed in areas with relatively soft geocryological conditions, preliminary degassing of permafrost depth intervals, passive and active heat isolation installation to the sub-wellhead part of the production well and around wellhead, and mechanical strengthening of unstable wells. Current plans are underway to utilize this experience for new gas discoveries in the Russian Arctic. Full article

(This article belongs to the Special Issue Current Technical Problems of Conventional and Unconventional Oil and Gas Recovery)

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20 pages, 6236 KiB

Open AccessArticle

South Anze Structure and Its Control on Coalbed Methane Aggregation in the Qinshui Basin and the Mechanism of Syncline Gas Enrichment in the Qinshui Basin

by Bo Wang, Qingtian Zhang, Zhenghui Qu and Yiteng Zhang

Energies 2023, 16(11), 4521; https://doi.org/10.3390/en16114521 - 4 Jun 2023

Cited by 2 | Viewed by 1363

Abstract

The phenomenon of coalbed-methane synclinal accumulation in the Qinshui Basin has been widely reported, but it has mainly been observed in the core block of the Qinshui Syncline. The questions arise: does this phenomenon exist in the wing of the Qinshui Syncline and, [...] Read more.

The phenomenon of coalbed-methane synclinal accumulation in the Qinshui Basin has been widely reported, but it has mainly been observed in the core block of the Qinshui Syncline. The questions arise: does this phenomenon exist in the wing of the Qinshui Syncline and, if so, what is the mechanism behind it? Further study is required to answer these questions. This paper focuses on the South Anze No. 3 coal seam in the Qinshui Basin as an example. It conducts a systematic sorting of coalbed-methane geological characteristics and an analysis of the effects of structural assemblage characteristics, genetic mechanisms, and structural control on coalbed-methane accumulation. Additionally, it examines the basin structure and evolution during the critical period of the Qinshui Basin, as well as the gas geological characteristics of adjacent areas, in order to discuss the gas-rich mechanism of the syncline in the Qinshui Basin. Key insights obtained from the study include the following: (i) The whole South Anze is a nosing structure that plunges from west to east and superposes secondary folds and faults in different directions. Four deformation zones can be identified based on the characteristics of structural assemblage, including NEN-oriented compressive structures, ENE-trend shear fractures, EW-trend compressive fractures, and EW-trend compressive folds. The formation of structural assemblage in the study area is attributed to the compression in the Indosinian and Yanshanian, and the fault inversion in the Himalayan period. (ii) The ENE-trend shear fracture deformation area located in the nosing uplift is a low CBM (coalbed methane) content area due to gas diffusion during the Himalayan extension. The syncline in the combination of NEN-trend and EW-trend “ejective folds” in the west and south of the study area is a high-value area of coalbed-methane content. It is further verified that the law of syncline gas accumulation in the Qinshui Basin is also applicable to the wing of the Qinshui Syncline. (iii) Since the formation of the Qinshui Syncline, the main coal seam has been in an extensional environment below the neutral plane, resulting in the main dissipation of coalbed methane. During its geological history, surface water penetrated the aquifer above the main coal seam through two channels: the extensional area above the neutral plane of the adjacent anticline and the shear fracture. A hydrostatic pressure seal is formed in the Qinshui Syncline and the secondary syncline is superimposed upon it, which is the cause of gas enrichment in the syncline of the Qinshui Basin. (iv) Weak deformation in the syncline basin is the focus of global coalbed-methane exploration and development. The mechanism proposed in this paper can provide ideas and references for further understanding of coalbed-methane enrichment in this type of basin. Full article

(This article belongs to the Special Issue Coalbed Methane Exploration and Production)

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39 pages, 3975 KiB

Open AccessArticle

Forecasting the Return of Carbon Price in the Chinese Market Based on an Improved Stacking Ensemble Algorithm

by Peng Ye, Yong Li and Abu Bakkar Siddik

Energies 2023, 16(11), 4520; https://doi.org/10.3390/en16114520 - 4 Jun 2023

Cited by 1 | Viewed by 2145

Abstract

Recently, carbon price forecasting has become critical for financial markets and environmental protection. Due to their dynamic, nonlinear, and high noise characteristics, predicting carbon prices is difficult. Machine learning forecasting often uses stacked ensemble algorithms. As a result, common stacking has many limitations [...] Read more.

Recently, carbon price forecasting has become critical for financial markets and environmental protection. Due to their dynamic, nonlinear, and high noise characteristics, predicting carbon prices is difficult. Machine learning forecasting often uses stacked ensemble algorithms. As a result, common stacking has many limitations when applied to time series data, as its cross-validation process disrupts the temporal sequentiality of the data. Using a double sliding window scheme, we proposed an improved stacking ensemble algorithm that avoided overfitting risks and maintained temporal sequentiality. We replaced cross-validation with walk-forward validation. Our empirical experiment involved the design of two dynamic forecasting frameworks utilizing the improved algorithm. This incorporated forecasting models from different domains as base learners. We used three popular machine learning models as the meta-model to integrate the predictions of each base learner, further narrowing the gap between the final predictions and the observations. The empirical part of this study used the return of carbon prices from the Shenzhen carbon market in China as the prediction target. This verified the enhanced accuracy of the modified stacking algorithm through the use of five statistical metrics and the model confidence set (MCS). Furthermore, we constructed a portfolio to examine the practical usefulness of the improved stacking algorithm. Empirical results showed that the improved stacking algorithm could significantly and robustly improve model prediction accuracy. Support vector machines (SVR) aggregated results better than the other two meta-models (Random forest and XGBoost) in the aggregation step. In different volatility states, the modified stacking algorithm performed differently. We also found that aggressive investment strategies can help investors achieve higher investment returns with carbon option assets. Full article

(This article belongs to the Special Issue Climate Change in Times of Energy and Economic Crisis – the Role of Innovation and Economic Openness)

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25 pages, 1487 KiB

Open AccessFeature PaperArticle

Efficient Energy Management for the Smart Sustainable City Multifloor Manufacturing Clusters: A Formalization of the Water Supply System Operation Conditions Based on Monitoring Water Consumption Profiles

by Liudmyla Davydenko, Nina Davydenko, Agnieszka Deja, Bogusz Wiśnicki and Tygran Dzhuguryan

Energies 2023, 16(11), 4519; https://doi.org/10.3390/en16114519 - 4 Jun 2023

Cited by 4 | Viewed by 1918

Abstract

This study is devoted to improving the energy efficiency of urban infrastructure systems (UISs), in particular, the centralized water supply of a city multifloor manufacturing cluster (CMFMC), by developing the principles of effective energy consumption management. The CMFMCs are located in the residential [...] Read more.

This study is devoted to improving the energy efficiency of urban infrastructure systems (UISs), in particular, the centralized water supply of a city multifloor manufacturing cluster (CMFMC), by developing the principles of effective energy consumption management. The CMFMCs are located in the residential area of a megapolis and include manufacturing and service enterprises, residential and non-residential buildings, and a city logistics node. Demand monitoring and identification of the influence of seasonal and social environmental factors on its fluctuations is considered as a tool for identifying changes in the operating conditions of the water supply system (WSS) for the CMFMC facilities. To identify the typical operating conditions of water supply facilities, an approach is proposed that involves the analysis of daily water consumption profiles (WCPs). The formation of a database, the formation of groups of the same type of daily WCPs, and the construction of typical daily WCPs for typical groups and their description are the main stages of the proposed approach. The database contains a set of classification characteristics that describe the daily water consumption and its unevenness, as well as the shape of the daily WCP. The principal component analysis was applied to determine the dominant components of daily water consumption. A set of morphometric parameters was used to describe the shape of the daily WCPs. The methods of cluster and discriminant analysis were used to identify the influence of seasonality and social factors on water consumption and to form groups of the same type of daily WCPs. The analysis of sets of similar type of daily WCPs for typical days of typical seasons was carried out for a formalized description of the typical operating conditions of water supply facilities. The results of the analysis are the clarification of the equations of the dominant components of daily water consumption, the determination of the average values of the characteristics of daily water consumption, and the construction and description of typical daily WCPs for typical operating conditions of water supply facilities. The research results were obtained on the basis of the data of the monitoring systems for water supply enterprises in Ukraine and Poland in 2021–2022. The obtained results are the basis for planning the water supply process and adjusting the operation modes of WSS pumping stations for the CMFMC, as well as planning power consumption for typical operating conditions, which will contribute to increasing the efficiency of water and electricity use. Full article

(This article belongs to the Special Issue Advances in Energy Transition in Transport and Logistics in Modern, Low-Emission, Smart and Sustainable Cities)

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26 pages, 11673 KiB

Open AccessArticle

Numerical Investigation on the Influence of Injection Location and Injection Strategy on a High-Pressure Direct Injection Diesel/Methanol Dual-Fuel Engine

by Huabing Wen, Yue Yu, Jingrui Li, Changchun Xu, Haiguo Jing and Jianhua Shen

Energies 2023, 16(11), 4518; https://doi.org/10.3390/en16114518 - 4 Jun 2023

Cited by 5 | Viewed by 1771

Abstract

High-pressure direct injection diesel/methanol dual-fuel engines exhibit excellent emission reduction potential, but they are still in the initial stage of research and development. The influences of different methanol injection locations, injection duration, and injection pressures on combustion characteristics, mixture homogeneity, and exhaust emissions [...] Read more.

High-pressure direct injection diesel/methanol dual-fuel engines exhibit excellent emission reduction potential, but they are still in the initial stage of research and development. The influences of different methanol injection locations, injection duration, and injection pressures on combustion characteristics, mixture homogeneity, and exhaust emissions are investigated to explore appropriate injection strategies and further optimize the engine performance base using CONVERGE software. The results show that the impact of the methanol injection position on the engine is relatively small, especially on combustion characteristics. A larger axial nozzle distance contributes to the formation of the homogeneous mixture, improving the engine economy. However, the engine performance is remarkably affected by methanol injection duration and methanol injection pressure. A shorter combustion duration is achieved with a decrease in the methanol injection duration and an increase in the methanol injection pressure, as a result of which the fuel economy is improved, with the combustion process more concentrated near the top dead center. Simultaneously, the mixture homogeneity is enhanced, which is conducive to a reduction in soot and CO emissions, yet not to a NO_X and HC reduction. The lowest overall emissions of NO_X, soot, CO, and HC are achieved when the radial nozzle distance and axial nozzle distance are 2.5 mm and 0.5 mm, respectively. Besides, the combustion characteristics and emissions of the engine are affected significantly under different methanol injection locations and injection pressures. The increased injection interval leads to deteriorating combustion characteristics and economy, i.e., a delayed combustion phase (CA50), an extended ignition delay and combustion duration (CA10–CA90), thereby increasing CO and soot emissions, but decreasing NO_X emission. Additionally, the optimal economy and exhaust emissions are obtained when adopting an injection duration of 6 °CA and an injection pressure of 44.4 MPa. The ITE is increased in this case compared to the other injection strategies, thereby improving the engine performance significantly. The results provide parametric feedback and theoretical support for the design of high-pressure direct injection diesel/methanol dual-fuel engines from a time and space perspective, which has certain theoretical significance. Full article

(This article belongs to the Special Issue Advanced Research on Internal Combustion Engines and Engine Fuels)

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13 pages, 7158 KiB

Open AccessCommunication

Operational Stability of Hydropower Plant with Upstream and Downstream Surge Chambers during Small Load Disturbance

by Yi Liu, Xiaodong Yu, Xinlei Guo, Wenlong Zhao and Sheng Chen

Energies 2023, 16(11), 4517; https://doi.org/10.3390/en16114517 - 4 Jun 2023

Cited by 2 | Viewed by 1493

Abstract

A surge chamber is a common pressure reduction facility in a hydropower plant. Owing to large flow inertia in the upstream headrace tunnel and downstream tailrace tunnel, a hydropower plant with upstream and downstream surge chambers (HPUDSC) was adopted. This paper aimed to [...] Read more.

A surge chamber is a common pressure reduction facility in a hydropower plant. Owing to large flow inertia in the upstream headrace tunnel and downstream tailrace tunnel, a hydropower plant with upstream and downstream surge chambers (HPUDSC) was adopted. This paper aimed to investigate the operational stability and nonlinear dynamic behavior of a HPUDSC. Firstly, a nonlinear dynamic model of the HPUDSC system was built. Subsequently, the operational stability and nonlinear dynamic behavior of the HPUDSC system were studied based on Hopf bifurcation theory and numerical simulation. Finally, the influencing factors of stability of the HPUDSC system were investigated. The results indicated the nonlinear HPUDSC system occurred at subcritical Hopf bifurcation, and the stability domain was located above the bifurcation curve, which provided a basis for the tuning of the governor parameters during operation. The dominant factors of stability and dynamic behavior of the HPUDSC system were flow inertia and head loss of the headrace tunnel and the area of the upstream surge chamber. Either increasing the head loss of the headrace tunnel and area of the upstream surge chamber or decreasing the flow inertia of the headrace tunnel could improve the operational stability of the HPUDSC. The proposed conclusions are of crucial engineering value for the stable operation of a HPUDSC. Full article

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

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39 pages, 3231 KiB

Open AccessReview

A Review of Pumped Hydro Storage Systems

by Papadakis C. Nikolaos, Fafalakis Marios and Katsaprakakis Dimitris

Energies 2023, 16(11), 4516; https://doi.org/10.3390/en16114516 - 4 Jun 2023

Cited by 23 | Viewed by 15644

Abstract

With the increasing global demand for sustainable energy sources and the intermittent nature of renewable energy generation, effective energy storage systems have become essential for grid stability and reliability. This paper presents a comprehensive review of pumped hydro storage (PHS) systems, a proven [...] Read more.

With the increasing global demand for sustainable energy sources and the intermittent nature of renewable energy generation, effective energy storage systems have become essential for grid stability and reliability. This paper presents a comprehensive review of pumped hydro storage (PHS) systems, a proven and mature technology that has garnered significant interest in recent years. The study covers the fundamental principles, design considerations, and various configurations of PHS systems, including open-loop, closed-loop, and hybrid designs. Furthermore, the review highlights the crucial role of PHS systems in integrating renewable energy sources, mitigating peak load demands, and enhancing grid stability. An in-depth analysis of current and emerging trends, technical challenges, environmental impacts, and cost-effectiveness is also provided to identify potential areas for future research and development. The paper concludes by offering a perspective on the challenges and opportunities that PHS systems present, underlining their potential to significantly contribute to a sustainable and reliable energy future. Full article

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13 pages, 4449 KiB

Open AccessArticle

Effect of the Volumetric Flow Rate Measurement Methodology of Positive Pressure Ventilators on the Parameters of the Drive Unit

by Łukasz Warguła, Piotr Kaczmarzyk, Piotr Lijewski, Paweł Fuć, Filip Markiewicz, Daniel Małozięć and Bartosz Wieczorek

Energies 2023, 16(11), 4515; https://doi.org/10.3390/en16114515 - 4 Jun 2023

Cited by 6 | Viewed by 1579

Abstract

The nature and conditions of the execution of tests (open or duct flow) in terms of evaluating the flow rate generated by positive pressure ventilators (PPV) may affect the parameters of the drive unit recorded during testing. In this article, popular PPVs (conventional [...] Read more.

The nature and conditions of the execution of tests (open or duct flow) in terms of evaluating the flow rate generated by positive pressure ventilators (PPV) may affect the parameters of the drive unit recorded during testing. In this article, popular PPVs (conventional type—W1 and turbo type—W2) of about 4.2 kW were tested under open flow (Method A) and duct flow (Method B) conditions. During the tests, engine load values were recorded: torque, speed, horsepower and, using portable emissions measurement systems (PEMS), exhaust gas emissions: carbon monoxide (CO), carbon dioxide (CO₂), hydrocarbons (HC), nitrogen oxides (NO_x) and fuel consumption. Depending on the method used to measure ventilator flow rates, drive units can have different drive power requirements (from 3.2% to 4.5%). Changes in drive unit operating conditions induced by the flow measurement method are observed in the results of fuel consumption (from 0.65% to 9.8%) and emissions of harmful exhaust compounds: CO₂ up to 2.4%, CO up to 67%, HC up to 93.2% and NO_x up to 37%. The drive units of turbo type fans (W2) are more susceptible to the influence of the test methods in terms of flow assessment, where they have higher emissions of harmful exhaust gases when tested by Method A. Flow measurement methods affect the oscillation of propulsion power, which contributes to disturbances in the control of the fuel–air mixture composition. The purpose of this article is to analyse the impact of testing methods for measuring the flow rate of positive pressure ventilators on the performance of the drive unit. Full article

(This article belongs to the Special Issue Internal Combustion Engine: Research and Application)

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26 pages, 17448 KiB

Open AccessArticle

Selected Simulation and Experimental Studies of the Heat Transfer Process in the Railway Disc Brake in High-Speed Trains

by Jacek Kukulski, Andrzej Wolff and Sławomir Walczak

Energies 2023, 16(11), 4514; https://doi.org/10.3390/en16114514 - 4 Jun 2023

Cited by 6 | Viewed by 1821

Abstract

The effectiveness of railway brakes strongly depends on their thermal condition. A computer simulation and experimental investigations on a full-scale dynamometric stand were chosen as an adequate analysis of the heat transfer process in brakes. The article introduces a two-dimensional, axisymmetric numerical model [...] Read more.

The effectiveness of railway brakes strongly depends on their thermal condition. A computer simulation and experimental investigations on a full-scale dynamometric stand were chosen as an adequate analysis of the heat transfer process in brakes. The article introduces a two-dimensional, axisymmetric numerical model of the tested disc brake. Boundary conditions related to the heat generated in the friction brake and heat transferred to the environment are also presented. The transient heat transfer problem was solved using the in-house computer program of the finite element method. The article presents simulations and experimental investigations of the intensive braking of a train with an initial high speed. Temperature responses of the disc brake on the friction surface and at other selected points are shown. In addition, a thermal imaging camera was used to assess the temperature distribution on the friction surface of the disc. The results of experimental and simulation tests were preliminarily compared. Similar maximum temperature values were obtained at the end of braking with a particular discrepancy in temperature responses during the analyzed process. Full article

(This article belongs to the Special Issue Energy in Modern Transportation – Problems of the System-of-Systems Approach to Low-Carbon Mobility and Logistic)

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16 pages, 3477 KiB

Open AccessArticle

Fault Detection and Power Loss Assessment for Rooftop Photovoltaics Installed in a University Campus, by Use of UAV-Based Infrared Thermography

by Kyoik Choi and Jangwon Suh

Energies 2023, 16(11), 4513; https://doi.org/10.3390/en16114513 - 4 Jun 2023

Cited by 3 | Viewed by 2035

Abstract

In contrast to commercial photovoltaic (PV) power plants, PV systems at universities are not actively monitored for PV module failures, which can result in a loss of power generation. In this study, we used thermal imaging with drones to detect rooftop PV module [...] Read more.

In contrast to commercial photovoltaic (PV) power plants, PV systems at universities are not actively monitored for PV module failures, which can result in a loss of power generation. In this study, we used thermal imaging with drones to detect rooftop PV module failures at a university campus before comparing reductions in power generation according to the percentage of module failures in each building. Toward this aim, we adjusted the four factors affecting the power generation of the four buildings to have the same values (capacities, degradations due to aging, and the tilts and orientation angles of the PV systems) and calibrated the actual monthly power generation accordingly. Consequently, we detected three types of faults, namely open short-circuits, hot spots, and potential-induced degradation. Furthermore, we found that the higher the percentage of defective modules, the lower the power generation. In particular, the annual power generation of the building with the highest percentage of defective modules (12%) was reduced by approximately 25,042 kWh (32%) compared to the building with the lowest percentage of defective modules (4%). The results of this study can contribute to improving awareness of the importance of detecting and maintaining defective PV modules on university campuses and provide a useful basis for securing the sustainability of green campuses. Full article

(This article belongs to the Special Issue Forecasting, Modeling, and Optimization of Photovoltaic Systems)

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21 pages, 14090 KiB

Open AccessFeature PaperArticle

Transport Phenomena in a Banded Solid Oxide Fuel Cell Stack—Part 2: Numerical Analysis

by Karol K. Śreniawski, Marcin Moździerz, Grzegorz Brus and Janusz S. Szmyd

Energies 2023, 16(11), 4512; https://doi.org/10.3390/en16114512 - 3 Jun 2023

Cited by 1 | Viewed by 1342

Abstract

Solid oxide fuel cells are recognized as a promising energy conversion technology. Crucial to the field is the opportunity to reduce the costs of prototyping methodology. Due to the difficulty of conducting direct measurements inside the electrodes and fuel cell’s channels, numerical modeling [...] Read more.

Solid oxide fuel cells are recognized as a promising energy conversion technology. Crucial to the field is the opportunity to reduce the costs of prototyping methodology. Due to the difficulty of conducting direct measurements inside the electrodes and fuel cell’s channels, numerical modeling remains the primary tool for improving the understanding and analyzing a fuel cell operation. Here, a computational fluid dynamic simulation of a banded solid oxide fuel cell’s stack, applied to enhance the geometrical design, is shown. A mathematical model, which includes momentum, heat, mass, and charge transport phenomena, was developed and used for the numerical simulation. The model was validated against the experimental study and confirmed its accuracy. The gas flow rate influence on the performance was investigated in details. Various arrangements of fuel and air channels were simulated and analyzed, including extending the system into a short stack. The proposed design modifications led to an increase in the volumetric power density of the stack compared to the existing prototype design. The proposed mathematical and numerical models were shown to be useful for testing further design modifications to the stack, including performance analysis, by changing the operating parameters of the system or applying new materials. Full article

(This article belongs to the Special Issue Current Advances in Fuel Cell Technology)

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25 pages, 32448 KiB

Open AccessFeature PaperArticle

Transport Phenomena in a Banded Solid Oxide Fuel Cell Stack—Part 1: Model and Validation

by Karol K. Śreniawski, Maciej Chalusiak, Marcin Moździerz, Janusz S. Szmyd and Grzegorz Brus

Energies 2023, 16(11), 4511; https://doi.org/10.3390/en16114511 - 3 Jun 2023

Cited by 2 | Viewed by 1453

Abstract

This paper primarily focuses on the formulation and validation of mathematical and numerical models for a new electrolyte-supported solid oxide fuel cell stack. By leveraging numerical modeling, the main goal is to deepen the understanding of the operational aspects and transport phenomena within [...] Read more.

This paper primarily focuses on the formulation and validation of mathematical and numerical models for a new electrolyte-supported solid oxide fuel cell stack. By leveraging numerical modeling, the main goal is to deepen the understanding of the operational aspects and transport phenomena within this system. The developed models are implemented in ANSYS, Inc., Fluent software, which enables a range of simulations. To validate the models, a stack fabrication methodology, a prototype construction, and conducted electrochemical tests were proposed. The simulated current-voltage characteristics for two different operating temperatures and three different fuel compositions were compared with the experimental measurements with satisfactory agreement. The counter-flow configuration was simulated and compared to the co-flow arrangement. The numerical simulation has demonstrated its efficacy in identifying possible design imperfections and enhancing the operational conditions of the prototype stack. Moreover, the developed model was further used, in Part 2 of this paper, to analyze the improvement options implementation for the next stage of the prototype. Full article

(This article belongs to the Special Issue Current Advances in Fuel Cell Technology)

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18 pages, 2708 KiB

Open AccessArticle

Decomposition Analysis and Trend Prediction of Energy-Consumption CO₂ Emissions in China’s Yangtze River Delta Region

by Yue Yuan and Sunhee Suk

Energies 2023, 16(11), 4510; https://doi.org/10.3390/en16114510 - 3 Jun 2023

Cited by 4 | Viewed by 1710

Abstract

This study calculated CO₂ emissions related to the consumption of primary energy by five sectors in the Yangtze River Delta region over 2000 to 2019. The Logarithmic Mean Divisia Index (LMDI) decomposition method was used to establish the factor decomposition model of [...] Read more.

This study calculated CO₂ emissions related to the consumption of primary energy by five sectors in the Yangtze River Delta region over 2000 to 2019. The Logarithmic Mean Divisia Index (LMDI) decomposition method was used to establish the factor decomposition model of CO₂ emissions change. The LMDI model was modified to assess the impact of five influencing factors, namely energy structure, energy intensity, industrial structure, economic output, and population size, on CO₂ emissions in the Yangtze River Delta region over the study period. The empirical results show that economic output has the largest positive effect on the growth in CO₂ emissions. Population size is the second most important factor promoting the growth in CO₂ emissions. Energy intensity is the most inhibitory factor to restrain CO₂ emissions, with a significant negative effect. Energy structure and industrial structure contribute insignificantly to CO₂ emissions. Using data on CO₂ emissions in the Yangtze River Delta region from 2000 to 2019, the GM (1, 1) model was applied for future forecasts of primary energy consumption and CO₂ emissions. Specific policy suggestions to mitigate CO₂ emissions in Yangtze River Delta region are provided. Full article

(This article belongs to the Special Issue Energy Transition and Sustainability: Low-Carbon Economy)

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12 pages, 2803 KiB

Open AccessPerspective

Exploring the Potential of Green Hydrogen Production and Application in the Antofagasta Region of Chile

by Emigdio Chavez-Angel, Alejandro Castro-Alvarez, Nicolas Sapunar, Francisco Henríquez, Javier Saavedra, Sebastián Rodríguez, Iván Cornejo and Lindley Maxwell

Energies 2023, 16(11), 4509; https://doi.org/10.3390/en16114509 - 3 Jun 2023

Cited by 7 | Viewed by 3950

Abstract

Green hydrogen is gaining increasing attention as a key component of the global energy transition towards a more sustainable industry. Chile, with its vast renewable energy potential, is well positioned to become a major producer and exporter of green hydrogen. In this context, [...] Read more.

Green hydrogen is gaining increasing attention as a key component of the global energy transition towards a more sustainable industry. Chile, with its vast renewable energy potential, is well positioned to become a major producer and exporter of green hydrogen. In this context, this paper explores the prospects for green hydrogen production and use in Chile. The perspectives presented in this study are primarily based on a compilation of government reports and data from the scientific literature, which primarily offer a theoretical perspective on the efficiency and cost of hydrogen production. To address the need for experimental data, an ongoing experimental project was initiated in March 2023. This project aims to assess the efficiency of hydrogen production and consumption in the Atacama Desert through the deployment of a mobile on-site laboratory for hydrogen generation. The facility is mainly composed by solar panels, electrolyzers, fuel cells, and a battery bank, and it moves through the Atacama Desert in Chile at different altitudes, from the sea level, to measure the efficiency of hydrogen generation through the energy approach. The challenges and opportunities in Chile for developing a robust green hydrogen economy are also analyzed. According to the results, Chile has remarkable renewable energy resources, particularly in solar and wind power, that could be harnessed to produce green hydrogen. Chile has also established a supportive policy framework that promotes the development of renewable energy and the adoption of green hydrogen technologies. However, there are challenges that need to be addressed, such as the high capital costs of green hydrogen production and the need for supportive infrastructure. Despite these challenges, we argue that Chile has the potential to become a leading producer and exporter of green hydrogen or derivatives such as ammonia or methanol. The country’s strategic location, political stability, and strong commitment to renewable energy provide a favorable environment for the development of a green hydrogen industry. The growing demand for clean energy and the increasing interest in decarbonization present significant opportunities for Chile to capitalize on its renewable energy resources and become a major player in the global green hydrogen market. Full article

(This article belongs to the Section A5: Hydrogen Energy)

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9 pages, 3029 KiB

Open AccessArticle

Metal-Tolerant Bioinoculant Pseudomonas putida KNP9 Mediated Enhancement of Soybean Growth under Heavy Metal Stress Suitable for Biofuel Production at the Metal-Contaminated Site

by Manishi Tripathi, Saurabh Kumar, Govind Makarana and Reeta Goel

Energies 2023, 16(11), 4508; https://doi.org/10.3390/en16114508 - 3 Jun 2023

Cited by 5 | Viewed by 1312

Abstract

The contamination of agricultural land with heavy metals is a global concern. Agricultural products produced in heavy metal-contaminated soil are prone to metal accumulation, and thus, are less fitted for consumption due to food safety issues. The cultivation of biofuel crops in contaminated [...] Read more.

The contamination of agricultural land with heavy metals is a global concern. Agricultural products produced in heavy metal-contaminated soil are prone to metal accumulation, and thus, are less fitted for consumption due to food safety issues. The cultivation of biofuel crops in contaminated soil would provide immediate economic benefit to the landholders while simultaneously reclaiming contaminated sites in the long run. The use of edible soybean for biodiesel production is discouraged due to the negative impact on food security. However, soybean produced in metal-contaminated soil would be suitable for biodiesel production. In this study, the tolerance and metal bioaccumulation potential of Pseudomonas putida KNP9 for Pb and Cd is investigated, and KNP9 is tested for soybean growth enhancement in cadmium and lead-amended soil. The maximum metal tolerance for the Pb and Cd in KNP9 was 1580 µM and 546 µM, respectively. KNP9 was found to be effective in removing both Pb and Cd from the solution. SEM-EDX revealed that KNP9 bioaccumulates both Pb and Cd. In pot trial studies, KNP9 was found to be effective in enhancing soybean growth with respect to untreated control under lead and cadmium stress. Thus, KNP9 inoculation protects soybean plants from the detrimental effects of cadmium and lead stress. Therefore, metal bioaccumulating bacterium P. putida KNP9 inoculation in soybean is a promising strategy for soybean growth enhancement, which could be utilized for enhanced biodiesel production from soybean at metal-contaminated sites. Full article

(This article belongs to the Special Issue Biomass and Biofuel for Renewable Energy)

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26 pages, 4084 KiB

Open AccessArticle

A Bi-Level Optimal Operation Model for Small-Scale Active Distribution Networks Considering the Coupling Fluctuation of Spot Electricity Prices and Renewable Energy Sources

by Yu Shi, Fei Lv, Xuefeng Gao, Minglei Jiang, Huan Luo and Ruhang Xu

Energies 2023, 16(11), 4507; https://doi.org/10.3390/en16114507 - 3 Jun 2023

Viewed by 1303

Abstract

As the penetration rate of variable renewable energy such as wind power increases in the power system, the composition and balance of the system also change gradually. The intermittency of renewable energy poses great stability challenges to the traditional centralized generation and load-oriented [...] Read more.

As the penetration rate of variable renewable energy such as wind power increases in the power system, the composition and balance of the system also change gradually. The intermittency of renewable energy poses great stability challenges to the traditional centralized generation and load-oriented transmission and distribution methods. Therefore, the Active Distribution Network Operator (ADNO) with distributed installation at the local level has a good application prospect in the new scenario. However, ADNO needs to improve its operational efficiency based on the types of local generation and storage devices and the nature of the market environment. To address this issue, this paper proposes a forecasting method that considers the coupling fluctuations of spot electricity prices and renewable energy, and a bi-level optimization operation method based on the Stackelberg game for optimizing the operation of small-scale ADNO under high wind power penetration rate. Simulation results show that the proposed methods achieve greater positive impact on the operational efficiency of ADNO than conventional methods. In addition, the proposed methods ensure the long-term profitability of ADNO, even with fluctuations in external factors. Full article

(This article belongs to the Section A: Sustainable Energy)

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