Energies

16 pages, 2525 KiB

Open AccessArticle

Fault Location Based on Comprehensive Grey Correlation Degree Analysis for Flexible DC Distribution Network

by Tianxiang Ma, Ziqi Hu, Yan Xu and Haoran Dong

Energies 2022, 15(20), 7820; https://doi.org/10.3390/en15207820 - 21 Oct 2022

Cited by 3 | Viewed by 1238

Flexible DC distribution networks have a strong capacity for new energy consumption and have received extensive attention from scholars in recent years, but fault location for DC distribution lines is a difficult task. To solve this problem, we propose using a comprehensive grey [...] Read more.

Flexible DC distribution networks have a strong capacity for new energy consumption and have received extensive attention from scholars in recent years, but fault location for DC distribution lines is a difficult task. To solve this problem, we propose using a comprehensive grey correlation degree analysis to analyze the similarity of aerial mode traveling differential current waveforms at the first and last ends of a DC line, thus achieving fault location by obtaining the optimal time shift. Additionally, we built a six-terminal flexible DC distribution network model in Matlab/Simulink for simulation and validation, showing that the method can complete the rapid and accurate location of all types of faults on a DC line, and that it possesses an anti-transition resistance capability, making it suitable and highly reliable for cases of low sampling frequency. Full article

(This article belongs to the Special Issue Advances in DC Technology for Modern Power Systems)

► Show Figures

Figure 1

9 pages, 2410 KiB

Open AccessArticle

Calculation Method for Assessing the Storage Capacity of Nitrogen Compounds in LNT Reactors

by Wojciech Kamela, Marcin K. Wojs and Piotr Orliński

Energies 2022, 15(20), 7819; https://doi.org/10.3390/en15207819 - 21 Oct 2022

Cited by 1 | Viewed by 944

Abstract

The presented study describes proprietary calculation methods that simulate the process of storing nitrogen dioxide elevation in a catalytic LNT reactor. The first section’s points of reference are the achievements of the article’s authors and the possibility of modeling NO₂ adsorption processes [...] Read more.

The presented study describes proprietary calculation methods that simulate the process of storing nitrogen dioxide elevation in a catalytic LNT reactor. The first section’s points of reference are the achievements of the article’s authors and the possibility of modeling NO₂ adsorption processes in LNT reactors. The rest of the article presents model calculations (proposed by the authors) of the course of the NO₂ storage process in LNT reactors. It considers one in its transition period, affecting the improvement and duration of the adsorption process. The conclusion presents selected results of simulation calculations obtained with the help of the equations’ authors and an evaluation of the results. A review of theoretical considerations is consistent with the experimental data, suggesting that the proposed computational solution may be used in future analytical validity assessments of LNT reactor tools under operating conditions. Full article

► Show Figures

Figure 1

18 pages, 2305 KiB

Open AccessArticle

Biodiesel Synthesis from Milk Thistle (Silybum marianum (L.) Gaertn.) Seed Oil using ZnO Nanoparticles as a Catalyst

by Hammad Ahmad Jan, Igor Šurina, Ahmed S. Al-Fatesh, Abdulaziz M. Almutlaq, Sher Wali and Anton Lisý

Energies 2022, 15(20), 7818; https://doi.org/10.3390/en15207818 - 21 Oct 2022

Cited by 3 | Viewed by 1606

Abstract

Biodiesel is considered valuable to reduce dependency on petrofuels. This work aimed to synthesize biodiesel from Silybum marianum using synthesized ZnO nanoparticles as a catalyst. The synthesized ZnO nanoparticles were examined by scanning electron microscopy and X-ray diffraction for confirmation. The synthesized biodiesel [...] Read more.

Biodiesel is considered valuable to reduce dependency on petrofuels. This work aimed to synthesize biodiesel from Silybum marianum using synthesized ZnO nanoparticles as a catalyst. The synthesized ZnO nanoparticles were examined by scanning electron microscopy and X-ray diffraction for confirmation. The synthesized biodiesel was confirmed by ASTM D-6751, H and C-NMR, GC-MS, and FT-IR spectroscopy. The optimum biodiesel yield of 91% was obtained with an oil-to-methanol ratio of 1:24, 15 mg of catalyst concentration, 60 °C temperature, and 45 min of reaction time. Fuel properties were determined according to the ASTM-defined methods and found within the defined limits of ASTM D-6751. ¹H-NMR and ¹³C-NMR showed characteristic peaks at 3.667 ppm, 2.000–2.060 ppm, 0.858–0.918 ppm, 5.288–5.407 ppm, 24.93–34.22 ppm, 172.71, 173.12, 130.16 ppm, and 128.14 ppm, respectively, which confirm biodiesel synthesis. The FAMEs composition of biodiesel was determined by GC-MS, which recognized 19 peaks for different types of FAMEs. FT-IR spectroscopy showed two main peaks, first in the range of 1725–1750 cm⁻¹ and second in the range of 1000–1300 cm⁻¹, which confirmed that the transesterification process had completed successfully. The physicochemical characteristics of Silybum marianum confirm that it is a suitable source to produce biodiesel on an industrial scale. Full article

(This article belongs to the Special Issue Plant Biomass for Chemicals and Biofuels Applications)

► Show Figures

Figure 1

18 pages, 3767 KiB

Open AccessArticle

Last Mile Logistics Life Cycle Assessment: A Comparative Analysis from Diesel Van to E-Cargo Bike

by Andrea Temporelli, Paola Cristina Brambilla, Elisabetta Brivio and Pierpaolo Girardi

Energies 2022, 15(20), 7817; https://doi.org/10.3390/en15207817 - 21 Oct 2022

Cited by 7 | Viewed by 3757

Abstract

With the proliferation of e-commerce, the field of last-mile logistics has grown increasingly, highlighting the need to manage the environmental consequences of this phenomenon, especially to achieve decarbonization targets for cities and to improve citizens’ quality of life. Within this framework, the authors [...] Read more.

With the proliferation of e-commerce, the field of last-mile logistics has grown increasingly, highlighting the need to manage the environmental consequences of this phenomenon, especially to achieve decarbonization targets for cities and to improve citizens’ quality of life. Within this framework, the authors carried out a last-mile logistics life cycle assessment, to analyse and compare different logistics vehicle options performing the same service in an urban context: an electric four-wheel cargo bike, an electric van, a plug-in hybrid van, and a diesel van. The assessment shows that the e-cargo bike performs better for all the impact categories considered. The second-best option is the e-van, while the diesel van shows the worst environmental results. Focusing on decarbonization, the replacement of a diesel van with an electric one or with an e-cargo bike allows a reduction of 173 g CO₂ eq/km and 250 g CO₂ eq/km, respectively. Similar results are obtained for Photochemical Ozone Formation with associated emissions of 0.18, 0.31, 0.45 and 0.49 g NMVOC eq/km for the e-cargo bike, e-van, plug in hybrid van and diesel van, respectively. The only exceptions are Human Health impact categories, Acidification and Respiratory inorganics, for which the plug-in hybrid van performs worst, and Resource use, Mineral and Metals, for which the electric van performs worst. Full article

► Show Figures

Graphical abstract

29 pages, 6462 KiB

Open AccessReview

A Review of Compensation Topologies and Control Techniques of Bidirectional Wireless Power Transfer Systems for Electric Vehicle Applications

by Murugan Venkatesan, Narayanamoorthi Rajamanickam, Pradeep Vishnuram, Mohit Bajaj, Vojtech Blazek, Lukas Prokop and Stanislav Misak

Energies 2022, 15(20), 7816; https://doi.org/10.3390/en15207816 - 21 Oct 2022

Cited by 31 | Viewed by 4155

Abstract

Owing to the constantly rising energy demand, Internal Combustion Engine (ICE)-equipped vehicles are being replaced by Electric Vehicles (EVs). The other advantage of using EVs is that the batteries can be utilised as an energy storage device to increase the penetration of renewable [...] Read more.

Owing to the constantly rising energy demand, Internal Combustion Engine (ICE)-equipped vehicles are being replaced by Electric Vehicles (EVs). The other advantage of using EVs is that the batteries can be utilised as an energy storage device to increase the penetration of renewable energy sources. Integrating EVs with the grid is one of the recent advancements in EVs using Vehicle-to-Grid (V2G) technology. A bidirectional technique enables power transfer between the grid and the EV batteries. Moreover, the Bidirectional Wireless Power Transfer (BWPT) method can support consumers in automating the power transfer process without human intervention. However, an effective BWPT requires a proper vehicle and grid coordination with reasonable control and compensation networks. Various compensation techniques have been proposed in the literature, both on the transmitter and receiver sides. Selecting suitable compensation techniques is a critical task affecting the various design parameters. In this study, the basic compensation topologies of the Series–Series (SS), Series–Parallel (SP), Parallel–Parallel (PP), Parallel–Series (SP), and hybrid compensation topology design requirements are investigated. In addition, the typical control techniques for bidirectional converters, such as Proportional–Integral–Derivative (PID), sliding mode, fuzzy logic control, model predictive, and digital control, are discussed. In addition, different switching modulation schemes, including Pulse-Width Modulation (PWM) control, PWM + Phase Shift control, Single-Phase Shift, Dual-Phase Shift, and Triple-Phase Shift methods, are discussed. The characteristics and control strategies of each are presented, concerning the typical applications. Based on the review analysis, the low-power (Level 1/Level 2) charging applications demand a simple SS compensation topology with a PID controller and a Single-Phase Shift switching method. However, for the medium- or high-power applications (Level 3/Level 4), the dual-side LCC compensation with an advanced controller and a Dual-Side Phase-Shift switching pattern is recommended. Full article

(This article belongs to the Special Issue Control, Estimation, Management and Fault Diagnosis of Electrical Vehicles Applications)

► Show Figures

Figure 1

20 pages, 5326 KiB

Open AccessArticle

Geochemical Characteristics of the Chang 7 Source Rocks of the Triassic Yanchang Formation in Ordos Basin, China: Implications for Organic Matter Accumulation and Shale Oil Potential

by Lewei Hao, Xiaofeng Ma, Wenqiang Gao, Zhaocai Ren, Huifei Tao and Weikai Huang

Energies 2022, 15(20), 7815; https://doi.org/10.3390/en15207815 - 21 Oct 2022

Cited by 3 | Viewed by 1274

Abstract

The Chang 7 member of the Upper Triassic Yanchang Formation in the Ordos Basin is considered to hold the main source rocks for conventional and unconventional oil and gas. The lamination or lithology alteration in vertical and lateral directions, even over a short [...] Read more.

The Chang 7 member of the Upper Triassic Yanchang Formation in the Ordos Basin is considered to hold the main source rocks for conventional and unconventional oil and gas. The lamination or lithology alteration in vertical and lateral directions, even over a short distance, is a common feature in lacustrine source rocks. The differences in the geochemical characteristics of black shales, dark mudstones and interbedded sandstones have been scarcely reported, and their influences on the petroleum generation potential and shale oil potential are not clear. To this end, 22 core samples were collected from the Lower and Middle Chang 7 (C7-3 and C7-2) members of the Triassic from well CYX in the Qingcheng area. By conducting a series of geochemical analyses including TOC, Rock-Eval pyrolysis yields, bitumen extraction and quantification, and the separation and quantification of saturates, aromatics, resins and asphaltenes, along with biomarker analyses, several results were found. Firstly, the C7-3 and C7-2 source rocks are thermally mature and have entered into the stage of hydrocarbon generation. The C7-3 and C7-2 source rocks have a good to very good hydrocarbon generation potential especially the C7-3 black shales. Secondly, terrigenous source input is more abundant in C7-2, whereas the source input of phytoplankton, algae or microbial lipids is more abundant in C7-3. Moreover, a high TOC content basically corresponds to low wax indexes, terrigenous/aquatic ratios (TARs), and Pr/nC₁₇ and Ph/nC₁₈ ratios and high C₂₇/C₂₉ regular sterane ratios, which suggests that the source input of phytoplankton, algae or microbial lipids is favorable for OM accumulation. Third, analyses of the molecular composition of saturated fractions in shales and interbedded sandstones and the production index demonstrate the migration of petroleum from organic-rich source rocks to their organic-lean counterparts. The C7-2 dark mudstones could be considered as a potential “sweet spot” since their oil saturation index (OSI) was the highest among all the studied samples and they are more enriched in light aliphatic fractions. Full article

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

► Show Figures

Figure 1

17 pages, 7442 KiB

Open AccessArticle

Modified Cascaded Controller Design Constructed on Fractional Operator ‘β’ to Mitigate Frequency Fluctuations for Sustainable Operation of Power Systems

by Muhammad Majid Gulzar, Sadia Murawwat, Daud Sibtain, Kamal Shahid, Imran Javed and Yonghao Gui

Energies 2022, 15(20), 7814; https://doi.org/10.3390/en15207814 - 21 Oct 2022

Cited by 9 | Viewed by 1454

Abstract

The demand for energy is increasing at an abrupt pace, which has highly strained the power system, especially with high share of power generation from renewable energy sources (RES). This increasing strain needs to be effectively managed for a continuous and smooth operation [...] Read more.

The demand for energy is increasing at an abrupt pace, which has highly strained the power system, especially with high share of power generation from renewable energy sources (RES). This increasing strain needs to be effectively managed for a continuous and smooth operation of the power system network. Generation and demand exhibit a strong correlation that directly creates an impact on the power system frequency. Fluctuations and disruptions in load frequency can manifest themselves as over-voltages and physical damages in the power grid and, in the worst case, can lead to blackouts. Thus, this paper proposed an effective solution to mitigate the load frequency problem(s), which is initiated by the changing load demand under high penetration of RES. This paper presented an improved cascaded structure, the proportional integral with a fractional operator coupled with proportional derivative

(PI - ({FO}_{P} + PD))

. The proposed

{FO}_{P} + PD

modifies the (1+PD) controller by introducing fractional properties that improve its tracking efficiency and mitigate frequency fluctuations taking minimal time. The introduction of

{FO}_{P} (β)

diversifies its tracking and overall controlling ability, which translates it as a significant controller. The controller optimal parameters are extracted by deploying a dragonfly search algorithm (DSA). The study of the results illustrates that the proposed design displays efficient performance under any disturbance or uncertainty in the power system. Full article

(This article belongs to the Special Issue Control of Renewable Energy Sources in Power Systems and Smart Grids)

► Show Figures

Figure 1

29 pages, 13352 KiB

Open AccessArticle

Properties of Modified Warm-Mix Asphalt Mixtures Containing Different Percentages of Reclaimed Asphalt Pavement

by Hayder Abbas Obaid, Tameem Mohammed Hashim, Ahmed Awad Matr Al-Abody, Mohammed Salah Nasr, Ghadeer Haider Abbas, Abdullah Musa Kadhim and Monower Sadique

Energies 2022, 15(20), 7813; https://doi.org/10.3390/en15207813 - 21 Oct 2022

Cited by 2 | Viewed by 1577

Abstract

The Rapid reduction of energy resources and the escalated effects of global warming have created a strong motivation to find some new techniques in the field of paving construction. Adopting new technologies, such as warm-mix asphalt (WMA) or the recycling process of asphalt [...] Read more.

The Rapid reduction of energy resources and the escalated effects of global warming have created a strong motivation to find some new techniques in the field of paving construction. Adopting new technologies, such as warm-mix asphalt (WMA) or the recycling process of asphalt can be very helpful for the economy and have a significant impact on the environmental footprint. Thus, this research aimed to study the mechanical and durable characteristics of modified WMA mixtures using (1.0%, 1.5%, and 2.0%) Sasobit REDUX^®, (0.3%, 0.4%, and 0.5%) Aspha-Min^®, and (0.07%, 0.1%, and 0.125) ZycoTherm^® additives corresponding to three percentages of reclaimed asphalt pavement (RAP) (20%, 40%, and 60%). Three mixing temperatures have been conducted in this study to generate WMA mixtures at (135 °C, 125 °C, and 115 °C) corresponding to three compacting temperatures (125 °C, 115 °C, and 105 °C). The mechanical properties of the developed WMA mixtures have been evaluated using the Superpave volumetric properties (air voids, voids filled with asphalt, and voids in mineral aggregate), while the durable properties have been investigated using the resilient modulus test (M_R) at 25 °C, resilient modulus ratio (RM_R), and Hamburg wheel-track test in terms of permanent deformation, moisture susceptibility, and rutting resistance. To make the WMA mixtures accept high quantities of RAP (>25%), an insignificant increase in the amounts of WMA additives was needed to produce mixtures carrying sustainability labels. Results indicated that all the used additives had pushed the WMA mixtures to achieve considerable mechanical properties, whereas the best properties for the WMA mixtures containing 0%, 20%, 40%, and 60% of RAP have been achieved by mixing with (1.0% Sasobit REDUX^® @ 125 °C), (1.0% Sasobit REDUX^® or 0.3% Aspha-Min^® @ 135 °C), (1.5% Sasobit REDUX^® @ 125 °C), and (2.0% Sasobit REDUX^® or 0.5% Aspha-Min^® @ 135 °C), respectively. On another hand, the best durable properties have been achieved by mixing the mentioned WMA mixtures containing 0%, 20%, 40%, and 60% of RAP with 0.07%, 0.07%, 0.1%, and 0.125% of ZycoTherm^® at 153 °C, respectively. Using such additives in the recycled WMA mixtures made it possible to activate waste recycling in the paving industry. Full article

(This article belongs to the Special Issue Low-Carbon Energy Systems: Recent Engineering Materials and Technologies)

► Show Figures

Figure 1

2 pages, 161 KiB

Open AccessEditorial

Building Energy: Economics and Environment

by Robert Dylewski and Janusz Adamczyk

Energies 2022, 15(20), 7812; https://doi.org/10.3390/en15207812 - 21 Oct 2022

Viewed by 913

Abstract

Decreasing the negative impact of buildings on the environment is a major challenge [...] Full article

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

21 pages, 8550 KiB

Open AccessArticle

A Current Sensorless Control of Buck-Boost Converter for Maximum Power Point Tracking in Photovoltaic Applications

by Nabil Obeidi, Mostefa Kermadi, Bachir Belmadani, Abdelkarim Allag, Lazhar Achour and Saad Mekhilef

Energies 2022, 15(20), 7811; https://doi.org/10.3390/en15207811 - 21 Oct 2022

Cited by 5 | Viewed by 1613

Abstract

In the present paper, a current sensorless (CSL) method for buck-boost converter control is proposed for maximum power point tracking (MPPT) photovoltaic applications. The proposed control scheme uses the mathematical model of the buck-boost converter to derive a predefined objective function for the [...] Read more.

In the present paper, a current sensorless (CSL) method for buck-boost converter control is proposed for maximum power point tracking (MPPT) photovoltaic applications. The proposed control scheme uses the mathematical model of the buck-boost converter to derive a predefined objective function for the MPPT control. The proposed scheme does not require any current sensor and relies only on the input voltage signal, which decreases the implementation cost. The proposed method is successfully implemented using a Matlab/Simulink/Stateflow environment, and its effectiveness is compared over the perturb and observe (P&O) method. An experimental rig, that includes a buck-boost converter, a PV simulator, and a resistive load, is used for the experimental validation. A rapid Arduino prototyping platform is used for the digital implementation, where the SAM3X8E microcontroller of the Arduino DUE board, which integrates an ARM Cortex-M3 MCU, is used as a target hardware for the proposed model-based controller developed under the Stateflow environment. Furthermore, the integrated pulse width modulation (PWM) macrocell is used to generate accurate PWM gate-drive signals for the buck-boost converter. Compared to the P&O, the presented simulation and experimental results show that the proposed method has reduced the computation burden and the sensor cost of implementation by 24.3%, and 27.95%, respectively. Full article

(This article belongs to the Special Issue Advanced Research on the Control of Power Converters)

► Show Figures

Figure 1

17 pages, 7607 KiB

Open AccessReview

Hybrid Indirect Evaporative Cooling-Mechanical Vapor Compression System: A Mini-Review

by Qian Chen, Muhammad Burhan, M Kum Ja, Muhammad Wakil Shahzad, Doskhan Ybyraiymkul, Hongfei Zheng, Xin Cui and Kim Choon Ng

Energies 2022, 15(20), 7810; https://doi.org/10.3390/en15207810 - 21 Oct 2022

Cited by 2 | Viewed by 1838

Abstract

The hybrid indirect evaporative cooling-mechanical vapor compression (IEC-MVC) process is deemed a promising cooling system for hot and humid areas. It possesses the merits of high energy efficiency and strong capability of temperature and humidity control. Herein, we provide an overview of the [...] Read more.

The hybrid indirect evaporative cooling-mechanical vapor compression (IEC-MVC) process is deemed a promising cooling system for hot and humid areas. It possesses the merits of high energy efficiency and strong capability of temperature and humidity control. Herein, we provide an overview of the state-of-the-art investigations over different aspects of the hybrid IEC-MVC process. Firstly, we evaluate the potential of IEC as a pre-cooler and heat-recovery device. Then, we compare the energy efficiency of IEC-MVC with standalone MVC and summarize its long-term energy-saving potential under specific weather conditions. Subsequently, we discuss the economic viability and water consumption of the hybrid process. These studies form a solid foundation for the future installation of the IEC-MVC system. Full article

(This article belongs to the Special Issue Research and Development on Indirect Evaporative Cooling Technology)

► Show Figures

Figure 1

15 pages, 3882 KiB

Open AccessArticle

Frequency of Damage of Low Voltage Apparatus Due to Lightning Flashes to Ground Nearby HV Overhead Lines

by Tomasz Kisielewicz, Giovanni Battista Lo Piparo and Carlo Mazzetti

Energies 2022, 15(20), 7809; https://doi.org/10.3390/en15207809 - 21 Oct 2022

Cited by 2 | Viewed by 1155

Abstract

The paper deals with a simplified approach to evaluate the frequency of damage of low voltage apparatus powered by a in housing HV/LV transformer against overvoltages due to nearby lightning flashes (source of damage S4 according to IEC 62,305 standard). The approach is [...] Read more.

The paper deals with a simplified approach to evaluate the frequency of damage of low voltage apparatus powered by a in housing HV/LV transformer against overvoltages due to nearby lightning flashes (source of damage S4 according to IEC 62,305 standard). The approach is based on computer simulations with validated models according to the current state of the art. The paper evaluates: the overvoltages stressing the HV/LV transformer due to lightning-induced over-voltages on the supplying HV overhead line; the voltage transferred to low voltage circuit through the power transformer and the influence of the transformer characteristics and of the LV circuits feeding the apparatus; the influence of the characteristics and the number of LV circuits on the frequency of damage of the apparatus. The different contributions to the voltage at the apparatus terminals, namely, the voltage transferred by the HV/LV transformer and the voltage induced by lightning current in the circuit downstream the transformer, are recognized. The voltage drop along the earthing system between the points where the transformer and the apparatus are earthed is, in the case considered, not effective because the apparatus and the transformer are bonded at the same point to the earthing system of the electrical installation. Even if these voltage components exhibit different shape and time at peak, for safety, they are added. When the resulting voltage is higher than the rated impulse voltage of apparatus insulation, damage of apparatus occurs. The evaluation allows to conclude that the frequency of damage of the LV apparatus supplied by circuits in a multipolar cable is about a thousand times lower than the one relevant to circuits in plastic conduit. If the tolerable frequency of damage of the LV apparatus is kept in the range of 0.01 damage/year, the adoption of protection measures against overvoltages caused by the source S4 is practically not necessary, except for the case of long circuits in conduit, powered by long HV overhead lines in areas with high values of lightning flash density. As this matter has not yet been considered in the IEC 62305 standard series, the results presented in this paper will be useful in the light of the revision of requirements of this standard. Full article

► Show Figures

Figure 1

18 pages, 6767 KiB

Open AccessArticle

Numerical and Experimental Spray Analysis of Castor and Jatropha Biodiesel under Non-Evaporating Conditions

by Muteeb ul Haq, Ali Turab Jafry, Muhammad Salman Abbasi, Muhammad Jawad, Saad Ahmad, Taqi Ahmad Cheema and Naseem Abbas

Energies 2022, 15(20), 7808; https://doi.org/10.3390/en15207808 - 21 Oct 2022

Cited by 8 | Viewed by 1424

Abstract

Fuel spray characteristics influence combustion, which in turn has a direct impact on engine performance and emissions. Recently, there has been an increasing interest in novel castor oil biodiesel. However, few investigations have been performed that combine both numerical and experimental biodiesel spray [...] Read more.

Fuel spray characteristics influence combustion, which in turn has a direct impact on engine performance and emissions. Recently, there has been an increasing interest in novel castor oil biodiesel. However, few investigations have been performed that combine both numerical and experimental biodiesel spray analyses. Hence, in this paper, we aim to explore the spray behavior of castor and jatropha biodiesel by employing numerical and experimental methods under non-evaporating, varying injection, and ambient conditions. The experimental study was carried out in a control volume vessel (CVV) at high injection and ambient pressures. The fuel atomization was modelled in ANSYS Fluent using a Lagrangian/Eulerian multiphase formulation. The results revealed that the Kelvin–Helmholtz and Rayleigh–Taylor (KHRT) model coupled with the Taylor Analogy Breakup (TAB) model provide a better estimation of the penetration length (PL) and spray cone angle (SCA) compared to the KH and TAB models. On average, Jatropha biodiesel (JB-20) and castor biodiesel (CB-20) showed a 10% to 22% longer PL, 8% to 10.6% narrower spray cone angles, and 3% to 6% less spray area, respectively, compared to diesel. The numerical predictions showed that JB-20 and CB-20 had an around 24.7–48.3% larger Sauter mean diameter (SMD) and a 38.6–73.3% average mean diameter (AMD). Full article

► Show Figures

Figure 1

19 pages, 3528 KiB

Open AccessArticle

Detection of Load-Altering Cyberattacks Targeting Peak Shaving Using Residential Electric Water Heaters

by El-Nasser S. Youssef, Fabrice Labeau and Marthe Kassouf

Energies 2022, 15(20), 7807; https://doi.org/10.3390/en15207807 - 21 Oct 2022

Cited by 2 | Viewed by 1368

Abstract

The rapid adoption of the smart grid’s nascent load-management capabilities, such as demand-side management and smart home systems, and the emergence of new classes of controllable high-wattage loads, such as energy storage systems and electric vehicles, magnify the smart grid’s exposure to load-altering [...] Read more.

The rapid adoption of the smart grid’s nascent load-management capabilities, such as demand-side management and smart home systems, and the emergence of new classes of controllable high-wattage loads, such as energy storage systems and electric vehicles, magnify the smart grid’s exposure to load-altering cyberattacks. These attacks aim at disrupting power grid services by staging a synchronized activation/deactivation of numerous customers’ high-wattage appliances. A proper defense plan is needed to respond to such attacks and maintain the stability of the grid, and would include prevention, detection, mitigation, incident response, and/or recovery strategies. In this paper, we propose a solution to detect load-altering cyberattacks using a time-delay neural network that monitors the grid’s load profile. As a case study, we consider a cyberattack scenario against demand-side management programs that control the loads of residential electrical water heaters in order to perform peak shaving. The proposed solution can be adapted to other load-altering attacks involving different demand-side management programs or other classes of loads. Experiments verify the proposed solution’s efficacy in detecting load-altering attacks with high precision and low false alarm and latency. Full article

(This article belongs to the Special Issue Smart Grid Cybersecurity: Challenges, Threats and Solutions)

► Show Figures

Figure 1

16 pages, 2366 KiB

Open AccessArticle

SSA-LSTM: Short-Term Photovoltaic Power Prediction Based on Feature Matching

by Zhengwei Huang, Jin Huang and Jintao Min

Energies 2022, 15(20), 7806; https://doi.org/10.3390/en15207806 - 21 Oct 2022

Cited by 15 | Viewed by 2051

Abstract

To reduce the impact of volatility on photovoltaic (PV) power generation forecasting and achieve improved forecasting accuracy, this article provides an in-depth analysis of the characteristics of PV power outputs under typical weather conditions. The trend of PV power generation and the similarity [...] Read more.

To reduce the impact of volatility on photovoltaic (PV) power generation forecasting and achieve improved forecasting accuracy, this article provides an in-depth analysis of the characteristics of PV power outputs under typical weather conditions. The trend of PV power generation and the similarity between simultaneous outputs are found, and a hybrid prediction model based on feature matching, singular spectrum analysis (SSA) and a long short-term memory (LSTM) network is proposed. In this paper, correlation analysis is used to verify the trend of PV power generation; the similarity between forecasting days and historical meteorological data is calculated through grey relation analysis; and similar generated PV power levels are searched for phase feature matching. The input time series is decomposed by singular spectrum analysis; the trend component, oscillation component and noise component are extracted; and principal component analysis and reconstruction are carried out on each component. Then, an LSTM network prediction model is established for the reconstructed subsequences, and the external feature input is controlled to compare the obtained prediction results. Finally, the model performance is evaluated through the data of a PV power plant in a certain area. The experimental results prove that the SSA-LSTM model has the best prediction performance. Full article

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

► Show Figures

Figure 1

23 pages, 1172 KiB

Open AccessReview

CO₂ Sequestration Overview in Geological Formations: Trapping Mechanisms Matrix Assessment

by Fatima Al Hameli, Hadi Belhaj and Mohammed Al Dhuhoori

Energies 2022, 15(20), 7805; https://doi.org/10.3390/en15207805 - 21 Oct 2022

Cited by 26 | Viewed by 3753

Abstract

This review focuses on the consequences of the early and rapid deployment of carbon dioxide (CO₂) capture and storage (CCS) technologies, which is currently recognized as a critical problem in fulfilling climate change mitigation objectives and as a viable alternative for [...] Read more.

This review focuses on the consequences of the early and rapid deployment of carbon dioxide (CO₂) capture and storage (CCS) technologies, which is currently recognized as a critical problem in fulfilling climate change mitigation objectives and as a viable alternative for countries throughout the world. Currently, the geological storage of CO₂ is the most effective and, in many cases, the only viable short- to medium-term alternative for considerably moving towards CO₂ sequestration in geological sinks and, thus, lowering net carbon emissions into the atmosphere. Furthermore, this review explores the global and environmental measurements of CO₂ emissions, as well as the emphasis behind more efficient energy usage. The components of the CCS system are briefly examined, with an emphasis on the technologies that have been developed by previous scholars to support carbon capture, as well as the kinds of carbon geological formations that are suitable sinks for CO₂. Additionally, the importance of carbon interaction and sequestration in unconventional formations are examined through case studies that are applied to coalbed seams and shale gas reservoirs. Numerous trapping processes are grouped and introduced in a constructive matrix to easily distinguish the broad trapping mechanisms, which are (1) chemical, (2) physicochemical, and (3) physical trapping, and each of these categories are further classified in depth based on their contribution to CO₂ storage. Full article

(This article belongs to the Section B3: Carbon Emission and Utilization)

► Show Figures

Figure 1

23 pages, 3442 KiB

Open AccessReview

Approaches to Disposal of Nuclear Waste

by Michael I. Ojovan and Hans J. Steinmetz

Energies 2022, 15(20), 7804; https://doi.org/10.3390/en15207804 - 21 Oct 2022

Cited by 37 | Viewed by 9846

Abstract

We present a concise mini overview on the approaches to the disposal of nuclear waste currently used or deployed. The disposal of nuclear waste is the end point of nuclear waste management (NWM) activities and is the emplacement of waste in an appropriate [...] Read more.

We present a concise mini overview on the approaches to the disposal of nuclear waste currently used or deployed. The disposal of nuclear waste is the end point of nuclear waste management (NWM) activities and is the emplacement of waste in an appropriate facility without the intention to retrieve it. The IAEA has developed an internationally accepted classification scheme based on the end points of NWM, which is used as guidance. Retention times needed for safe isolation of waste radionuclides are estimated based on the radiotoxicity of nuclear waste. Disposal facilities usually rely on a multi-barrier defence system to isolate the waste from the biosphere, which comprises the natural geological barrier and the engineered barrier system. Disposal facilities could be of a trench type, vaults, tunnels, shafts, boreholes, or mined repositories. A graded approach relates the depth of the disposal facilities’ location with the level of hazard. Disposal practices demonstrate the reliability of nuclear waste disposal with minimal expected impacts on the environment and humans. Full article

(This article belongs to the Special Issue Treatment of Radioactive Waste and Sustainability Energy)

► Show Figures

Figure 1

21 pages, 8009 KiB

Open AccessArticle

Analysis of the Influence of System Parameters on Launch Performance of Electromagnetic Induction Coil Launcher

by Shaohua Guan, Xiaocun Guan, Baoqi Wu and Jingbin Shi

Energies 2022, 15(20), 7803; https://doi.org/10.3390/en15207803 - 21 Oct 2022

Cited by 2 | Viewed by 1640

Abstract

The influence of electromagnetic induction coil launcher (EICL) system parameters on the launch performance was analyzed, and a method for measuring the launch performance of an EICL system with a muzzle velocity and energy conversion efficiency was proposed. The EICL system mainly includes [...] Read more.

The influence of electromagnetic induction coil launcher (EICL) system parameters on the launch performance was analyzed, and a method for measuring the launch performance of an EICL system with a muzzle velocity and energy conversion efficiency was proposed. The EICL system mainly includes a pulse power supply and launcher. The parameters of the pulse power supply mainly include the discharge voltage and the capacitance value of the capacitor bank. The structural parameters of the launcher mainly include the bore size of the launcher, the air gap length between the armature and the drive coil, the length and width of the drive coil, and the trigger position of the armature. Change in single or multiple parameters in the launch system will influence the launch performance. The influence of single or multiple parameters on the launch performance was summarized, and the physical law as analyzed. The influence law of the EICL system parameters on the launch performance was obtained, which lays a theoretical foundation for the optimization design of EICL. Finally, experimental verification was carried out by a single-stage test platform. Full article

(This article belongs to the Topic Energy Storage and Conversion Systems)

► Show Figures

Figure 1

16 pages, 5517 KiB

Open AccessArticle

Investigation on Flowback Behavior of Imbibition Fracturing Fluid in Gas–Shale Multiscale Pore Structure

by Jiajia Bai, Guoqing Wang, Qingjie Zhu, Lei Tao and Wenyang Shi

Energies 2022, 15(20), 7802; https://doi.org/10.3390/en15207802 - 21 Oct 2022

Cited by 2 | Viewed by 1076

Abstract

To investigate the influence of flowback time and flowback difference on flowback behavior of shale fracturing fluid, we carried out the permeability test experiment of Longmaxi Formation shale under different flowback pressure gradients and analyzed the retention characteristics of water phase in shale [...] Read more.

To investigate the influence of flowback time and flowback difference on flowback behavior of shale fracturing fluid, we carried out the permeability test experiment of Longmaxi Formation shale under different flowback pressure gradients and analyzed the retention characteristics of water phase in shale pores and fractures after flowback by nuclear magnetic resonance (NMR) instrument. The results indicate that after flowback under the pressure gradient ranges of 0.06~0.18 MPa/cm, the content of retained water phase in shale samples ranges from 9.68% to 16.97% and the retention of fracturing fluid in shale does not decrease with the increase of flowback pressure difference. Additionally, increasing the flowback pressure difference will reduce the shale permeability damage rate, but the permeability damage rate is still above 80%. After the flowback, the water phase mainly stays in the pore space with D < 100 nm, especially in the pore space with 2~10 nm and 10~50 nm. It is extremely difficult for the water phase in the pores with D < 100 nm to flow back out. The experimental results show that the critical flowback pressure gradient for particle migration of rock powder in shale fracture surface is 0.09 MPa/cm. The research results have important guiding significance for shale gas well flowback. Full article

(This article belongs to the Special Issue Reservoir Formation Damage Analysis)

► Show Figures

Figure 1

30 pages, 8492 KiB

Open AccessReview

Predictive Control Applied to Matrix Converters: A Systematic Literature Review

by Sergio Toledo, David Caballero, Edgar Maqueda, Juan J. Cáceres, Marco Rivera, Raúl Gregor and Patrick Wheeler

Energies 2022, 15(20), 7801; https://doi.org/10.3390/en15207801 - 21 Oct 2022

Cited by 4 | Viewed by 1638

Abstract

Power electronic devices play an important role in energy conversion. Among the options, matrix converters, in combination with predictive control, represent a good alternative for the power conversion stage. Although several reviews have been undertaken on this topic, they have been conducted in [...] Read more.

Power electronic devices play an important role in energy conversion. Among the options, matrix converters, in combination with predictive control, represent a good alternative for the power conversion stage. Although several reviews have been undertaken on this topic, they have been conducted in a non-systematic manner, without indicating how the studies considered were chosen. This paper presents results from a systematic literature review on predictive control applied to matrix converters that included 142 primary papers, which were selected after applying a defined protocol with clear inclusion and exclusion criteria. The study provides a detailed classification of predictive control methods and strategies applied to different matrix converter topologies. Research findings require to be understood in combination to develop a common understanding of the topic and ensure that future research effort is based on solid premises. In light of this, this study identifies and characterizes different predictive control techniques and matrix converter topologies through systematic literature review. The results of the review indicate that interest in the area is increasing. A number of open questions in the field are discussed. Full article

► Show Figures

Figure 1

18 pages, 26010 KiB

Open AccessArticle

Non-Intrusive Load Monitoring Based on Swin-Transformer with Adaptive Scaling Recurrence Plot

by Yongtao Shi, Xiaodong Zhao, Fan Zhang and Yaguang Kong

Energies 2022, 15(20), 7800; https://doi.org/10.3390/en15207800 - 21 Oct 2022

Cited by 4 | Viewed by 1393

Abstract

Non-Intrusive Load Monitoring (NILM) is an effective energy consumption analysis technology, which just requires voltage and current signals on the user bus. This non-invasive monitoring approach can clarify the working state of multiple loads in the building with fewer sensing devices, thus reducing [...] Read more.

Non-Intrusive Load Monitoring (NILM) is an effective energy consumption analysis technology, which just requires voltage and current signals on the user bus. This non-invasive monitoring approach can clarify the working state of multiple loads in the building with fewer sensing devices, thus reducing the cost of energy consumption monitoring. In this paper, an NILM method combining adaptive Recurrence Plot (RP) feature extraction and deep-learning-based image recognition is proposed. Firstly, the time-series signal of current is transformed into a threshold-free RP in phase space to obtain the image features. The Euclidean norm in threshold-free RP is scaled exponentially according to the voltage and current correlation to reflect the working characteristics of different loads adaptively. Afterwards, the obtained adaptive RP features can be mapped into images using the corresponding pixel value. In the load identification stage, an advanced computer vision deep network, Hierarchical Vision Transformer using Shifted Windows (Swin-Transformer), is applied to identify the adaptive RP images. The proposed solution is extensively verified by four real, measured load signal datasets, including industrial and household power situations, covering single-phase and three-phase electrical signals. The numerical results demonstrate that the proposed NILM method based on the adaptive RP can effectively improve the accuracy of load detection. Full article

► Show Figures

Figure 1

23 pages, 10757 KiB

Open AccessArticle

Numerical Study of Heat Transfer Enhancement by Arc-Shaped Fins in a Shell-Tube Thermal Energy Storage Unit

by Qicheng Chen, Junting Wu, Kanglong Sun and Yingjin Zhang

Energies 2022, 15(20), 7799; https://doi.org/10.3390/en15207799 - 21 Oct 2022

Cited by 5 | Viewed by 1317

Abstract

Latent heat thermal energy storage (LHTES) technology can alleviate the mismatch between the supply and demand of solar energy and industrial waste heat, but the low thermal conductivity of phase change materials (PCMs) is an issue that needs to be solved. In this [...] Read more.

Latent heat thermal energy storage (LHTES) technology can alleviate the mismatch between the supply and demand of solar energy and industrial waste heat, but the low thermal conductivity of phase change materials (PCMs) is an issue that needs to be solved. In this work, the effects of the bifurcated fins on melting and solidification are studied, and local and global entropy generation are discussed. The radial lag time and the circumferential lag time were defined to evaluate thermal penetration and thermal uniformity. Subsequently, a novel arc-shaped fin configuration was proposed to further enhance the heat transfer. The results showed that attaching the bifurcated fins could effectively reduce the global entropy generation. Increasing the trunk fin length was beneficial to enhance the thermal uniformity and promote the melting process, while increasing the branch fin was more effective in the solidification process. Overall, thermal uniformity determined the phase change process. More importantly, the concentric arc-shaped fins significantly reduced the heat transfer hysteresis region, showed better thermal performance than straights fins, and the energy storage and release time were reduced by 52.7% and 51.6%, respectively. Full article

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

► Show Figures

Figure 1

18 pages, 2584 KiB

Open AccessReview

Characterization of Rotational Magnetic Properties of Amorphous Metal Materials for Advanced Electrical Machine Design and Analysis

by Youguang Guo, Lin Liu, Xin Ba, Haiyan Lu, Gang Lei, Pejush Sarker and Jianguo Zhu

Energies 2022, 15(20), 7798; https://doi.org/10.3390/en15207798 - 21 Oct 2022

Cited by 7 | Viewed by 1619

Abstract

Amorphous metal (AM), specifically amorphous ferromagnetic metal, is considered as a satisfactory magnetic material for exploring electromagnetic devices with high-efficiency and high-power density, such as electrical machines and transformers, benefits from its various advantages, such as reasonably low power loss and very high [...] Read more.

Amorphous metal (AM), specifically amorphous ferromagnetic metal, is considered as a satisfactory magnetic material for exploring electromagnetic devices with high-efficiency and high-power density, such as electrical machines and transformers, benefits from its various advantages, such as reasonably low power loss and very high permeability in medium to high frequency. However, the characteristics of these materials have not been investigated comprehensively, which limits its application prospects to good-performance electrical machines that have the magnetic flux density with generally rotational and non-sinusoidal features. The appropriate characterization of AMs under different magnetizations is among the fundamentals for utilizing these materials in electrical machines. This paper aims to extensively overview AM property measurement techniques in the presence of various magnetization patterns, particularly rotational magnetizations, and AM property modeling methods for advanced electrical machine design and analysis. Possible future research tasks are also discussed for further improving AM applications. Full article

(This article belongs to the Special Issue Advanced Electrical Machine Design and Optimization)

► Show Figures

Figure 1

14 pages, 1790 KiB

Open AccessArticle

Influence of Reservoir Properties on the Velocity of Water Movement from Injection to Production Well

by Vladimir Valerievych Poplygin, Irina Sergeevna Poplygina and Viktor Antonovich Mordvinov

Energies 2022, 15(20), 7797; https://doi.org/10.3390/en15207797 - 21 Oct 2022

Cited by 3 | Viewed by 1176

Abstract

To maintain reservoir pressure, water is injected into oil reservoirs. In carbonate rock, water quickly breaks through fractures and highly permeable formations to production wells. This study analyzes the effect of the permeability, oil viscosity, pressure drop, and distance on the water velocity [...] Read more.

To maintain reservoir pressure, water is injected into oil reservoirs. In carbonate rock, water quickly breaks through fractures and highly permeable formations to production wells. This study analyzes the effect of the permeability, oil viscosity, pressure drop, and distance on the water velocity from an injection well to a production well. In the Tempest MORE hydrodynamic simulator (Roxar), a three-layer model of an oil reservoir was created, and water flow from an injection well to a production well was simulated with various values of the permeability, oil viscosity, and bottom hole pressure. The water velocity in the reservoir was estimated based on the mobility factor (k/µo). The results showed that at a mobility factor of less than 2 μm²/Pa s at a distance of 100 m in the reservoirs, the time of water migration from the injection well to the production well increased sharply, and at a mobility factor of more than 2 μm²/Pa s, it became shorter. An analysis of the time of water migration in fields with high-viscosity oil was conducted. The watering time turned out to be shorter than that predicted by the simulation. The permeability of the reservoir and the viscosity of the oil had the greatest influence on the water velocity. To a lesser extent, the time of water migration was affected by the distance between the wells and the difference in the bottomhole pressures. The average migration time for water with a mobility factor of more than 2 µm²/(Pa s) was 6.3 years. Based on the regression analysis of the field data, a linear equation for the time of water migration was obtained. The resulting equation makes it possible to predict the water cuts of wells and optimize oil production. Full article

(This article belongs to the Section H1: Petroleum Engineering)

► Show Figures

Figure 1

14 pages, 2079 KiB

Open AccessArticle

Influence of Standard Image Processing of 3D X-ray Microscopy on Morphology, Topology and Effective Properties

by Romain Guibert, Marfa Nazarova, Marco Voltolini, Thibaud Beretta, Gerald Debenest and Patrice Creux

Energies 2022, 15(20), 7796; https://doi.org/10.3390/en15207796 - 21 Oct 2022

Cited by 3 | Viewed by 1369

Abstract

Estimating porous media properties is a vital component of geosciences and the physics of porous media. Until now, imaging techniques have focused on methodologies to match image-derived flows or geomechanical parameters with experimentally identified values. Less emphasis has been placed on the compromise [...] Read more.

Estimating porous media properties is a vital component of geosciences and the physics of porous media. Until now, imaging techniques have focused on methodologies to match image-derived flows or geomechanical parameters with experimentally identified values. Less emphasis has been placed on the compromise between image processing techniques and the consequences on topological and morphological characteristics and on computed properties such as permeability. The effects of some of the most popular image processing techniques (filtering and segmentation) available in open source on 3D X-ray Microscopy (micro-XRM) images are qualitatively and quantitatively discussed. We observe the impacts of various filters such as erosion-dilation and compare the efficiency of Otsu’s method of thresholding and the machine-learning-based software Ilastik for segmentation. Full article

(This article belongs to the Special Issue Pore-Scale Multiphase Fluid Flow and Transport in Porous Media)

► Show Figures

Figure 1

11 pages, 4231 KiB

Open AccessArticle

Structural Evolution and Enhanced Piezoelectric Activity in Novel Lead-Free BaTiO₃-Ca(Sn_1/2Zr_1/2)O₃ Solid Solutions

by Ke Zhang, Pan Gao, Chang Liu, Xin Chen, Xinye Huang, Yongping Pu and Zenghui Liu

Energies 2022, 15(20), 7795; https://doi.org/10.3390/en15207795 - 21 Oct 2022

Cited by 1 | Viewed by 1121

Abstract

In this study, a series of solid solutions of (1−x)BaTiO₃-xCa(Sn_1/2Zr_1/2)O₃ (abbreviated as (1−x)BT-xCSZ, x = 0.00–0.15) ceramics have been prepared by the conventional solid-state reaction method to search [...] Read more.

In this study, a series of solid solutions of (1−x)BaTiO₃-xCa(Sn_1/2Zr_1/2)O₃ (abbreviated as (1−x)BT-xCSZ, x = 0.00–0.15) ceramics have been prepared by the conventional solid-state reaction method to search for high performance lead-free piezoelectric materials. The structural evolution, microstructure, and piezoelectric properties are investigated. X-ray diffraction (XRD) results indicate that the phase symmetry strongly depends on the CSZ content. A tetragonal phase is well-maintained in the compositions of 0 ≤ x ≤ 0.03, and coexistence of tetragonal and cubic phases is obtained in the range of x = 0.06–0.09, beyond which a pure cubic phase becomes stable. More importantly, a significantly enhanced piezoelectric coefficient of d₃₃ = 388 ± 9 pC/N is attained in the composition of x = 0.06 in the MPB region, where a tetragonal ferroelectric phase and an ergodic relaxor phase with average cubic symmetry coexist. Based on the analysis of crystal structure and dielectric properties, a temperature-composition phase diagram consisting of four phase regions is established. This study indicates that the lead-free BT-CSZ binary system has great potential for use in electromechanical transducer applications. Full article

(This article belongs to the Special Issue Advanced Materials for Energy Harvesting, Storage and Conversion)

► Show Figures

Figure 1

15 pages, 310 KiB

Open AccessArticle

The Relationship between Electricity Prices and Household Welfare in South Africa

by Bekithemba Qeqe, Forget Kapingura and Bahle Mgxekwa

Energies 2022, 15(20), 7794; https://doi.org/10.3390/en15207794 - 21 Oct 2022

Cited by 1 | Viewed by 1695

Abstract

The study examines the relationship between electricity prices and household welfare in South Africa. The study employs a demand system framework on annual time-series data from 2000 to 2018 and the analysis involves the calculation of price elasticities and measurement of welfare changes. [...] Read more.

The study examines the relationship between electricity prices and household welfare in South Africa. The study employs a demand system framework on annual time-series data from 2000 to 2018 and the analysis involves the calculation of price elasticities and measurement of welfare changes. The price elasticities in this study are drawn from the linear expenditure demand model. To analyse welfare change, we consider the impact of electricity pricing policies on cost of living (proxied by the consumer price index and households’ expenditure patterns). The study achieves this: (i) by comparing electricity price movements to changes in the rate of inflation between 2000 and 2018; (ii) by regressing total household energy expenditure against household expenditure on electricity, to examine how electricity costs affect a household’s overall energy bills; and (iii) thirdly, by regressing household food expenditure against households’ electricity expenditure to determine how the latter affects a household’s ability to spend on other basic goods and services. The results of the study show: (i) South African household electricity demand is inelastic to changes in price of electricity; (ii) electricity prices in the country increased at a higher rate than the rate of inflation for most of the time during the study period, suggesting that households incurred increased expenditures to achieve their desired utility or satisfy their energy needs during this period; (iii) household total electricity expenditure is positively related to household total energy expenditure, implying that high household expenditure on electricity exerts upward pressure on the overall household energy budgets; and (iv) household total food expenditure is negatively related to household total energy expenditure. This shows that while policy makers achieved significant success with providing physical access to electricity, affordable access to this basic service is still a concern and affects the overall welfare of households in the country. The study recommends a review of the country’s electricity tariff structure to make affordability a key objective. Moreover, the study calls for coordinated efforts in addressing Eskom challenges which have also played a contributing role to the current energy crisis, characterized by an unreliable electricity supply and constantly increasing electricity prices. Full article

14 pages, 2359 KiB

Open AccessArticle

Characteristics of Liquid-Hydrocarbon Yield and Biomarkers in Various Thermal-Evolution Stages: A Simulation Experiment with the Middle Jurassic Source Rocks in the Northern Margin of the Qaidam Basin

by Yongxin Chen, Xilong Zhang, Xiang Li, Tao Liu, Yaru Sun, Guotao Zhu and Pengfei Ju

Energies 2022, 15(20), 7793; https://doi.org/10.3390/en15207793 - 21 Oct 2022

Viewed by 1035

Abstract

Although there are many studies on the Jurassic source rocks in the northern margin of the Qaidam Basin, the characteristics of biomarkers and products with the same source rock in different evolutionary stages are still not well understood. Such an understanding is essential [...] Read more.

Although there are many studies on the Jurassic source rocks in the northern margin of the Qaidam Basin, the characteristics of biomarkers and products with the same source rock in different evolutionary stages are still not well understood. Such an understanding is essential for accurately estimating oil and gas resources. In order to explore the hydrocarbon-generation potential of high-quality source rocks of the Middle Jurassic and the evolution of liquid hydrocarbons and biomarkers, we carried out simulation research (under hydrous conditions) at various temperatures (250, 300, 350, 400 and 450 °C) with the mudstone of the Yu 33 well in the Yuka Sag. The results revealed that the “oil window” of the Middle Jurassic source rocks in the Yuka area was 300 °C (simulation temperature, Ro = 0.84%), but this was not the peak of hydrocarbon expulsion, which was gradually reached and stabilized above 350 °C. Overall, the concentration of alkanes and aromatics increased with temperature; although the concentration of alkanes was complex in the low evolutionary stages, temperature (simulated maturity) was still the main factor controlling the change in alkanes and aromatics. Among the maturity parameters of biomarkers, the ratio of ∑tricyclic terpanes/∑hopanes was the most effective parameter for indicating the maturity evolution of the Yuka area, but others were complicated by the increasing temperature. Therefore, when evaluating maturity, the applicability of other parameters needed to be fully considered. The results obtained offer new insights in the research on liquid-hydrocarbon and biomarker evolution of the Middle Jurassic source rocks in the Yuka Sag of the Qaidam Basin. Full article

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

► Show Figures

Figure 1

15 pages, 5187 KiB

Open AccessArticle

Aerogel Product Applications for High-Temperature Thermal Insulation

by Alexander V. Fedyukhin, Konstantin V. Strogonov, Olga V. Soloveva, Sergei A. Solovev, Irina G. Akhmetova, Umberto Berardi, Mark D. Zaitsev and Daniil V. Grigorev

Energies 2022, 15(20), 7792; https://doi.org/10.3390/en15207792 - 21 Oct 2022

Cited by 13 | Viewed by 2760

Abstract

This paper presents the results of theoretical and experimental studies to determine the optimal thickness of thermal insulation from basalt fiber and aerogel products for pipelines at temperatures of 300 and 600 °C. We carried out a comparison of the key thermophysical characteristics [...] Read more.

This paper presents the results of theoretical and experimental studies to determine the optimal thickness of thermal insulation from basalt fiber and aerogel products for pipelines at temperatures of 300 and 600 °C. We carried out a comparison of the key thermophysical characteristics of the claimed heat-insulating materials. We performed a thermal imaging survey of the furnace chimney, insulated with basalt fiber and aerogel, while controlling the temperature of the flue gases by establishing the required ratio of the flow rate of natural gas and oxidizer. The temperature gradient along the thickness of the thermal insulation was obtained using a numerical tool developed in ANSYS. The results show that aerogel surpasses basalt fiber in all key thermophysical characteristics. At the same time, the only barrier to widespread industrial production and use of aerogel in the high-temperature thermal insulation segment is its market cost, which is still several times higher than that of basalt fiber in terms of an equivalent performance. Full article

(This article belongs to the Special Issue Advanced Materials Research in Energy System)

► Show Figures

Figure 1

12 pages, 3804 KiB

Open AccessArticle

Dynamic-State Analysis of Inverter Based on Cascode GaN HEMTs for PV Application

by Yajing Zhang, Jianguo Li, Jiuhe Wang, Trillion Q. Zheng and Pengyu Jia

Energies 2022, 15(20), 7791; https://doi.org/10.3390/en15207791 - 21 Oct 2022

Cited by 4 | Viewed by 1237

Abstract

With the increase in renewable energy generation, microgrid has put forward higher requirements on the power density and performance of the photovoltaic inverter. In this paper, the dynamic process of inverter based on the cascode Gallium nitride (GaN) high electron mobility transistor (HEMT) [...] Read more.

With the increase in renewable energy generation, microgrid has put forward higher requirements on the power density and performance of the photovoltaic inverter. In this paper, the dynamic process of inverter based on the cascode Gallium nitride (GaN) high electron mobility transistor (HEMT) for the photovoltaic (PV) application is analyzed in detail. The parasitic inductors and capacitors have been considered in our proposed equivalent model, which can explain the phenomenon that the crossover time of the voltage and current is prolonged by the parasitic parameters. The influence of the parasitic parameters is identified through theoretical analysis. By analyzing the influence of parasitic parameters, the design process of high-frequency inverter can be optimized. A 500 W inverter based on the cascode GaN HEMT is built, and the correctness of theoretical and simulation analysis is verified by the experimental results. Full article

(This article belongs to the Special Issue Application Technology of Power Electronics in Renewable Energy Systems)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Energies, Volume 15, Issue 20 (October-2 2022) – 369 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI