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Energies, Volume 15, Issue 19 (October-1 2022) – 591 articles

Cover Story (view full-size image): Hybrid photovoltaic-concentrated solar power plants are an attractive option for supplying cheap and dispatchable solar electricity. Hybridization options for these technologies were investigated, combining their benefits through a deeper integration and using power-to-heat to store PV electricity in the thermal storage. Simulations of different systems were performed for different sites, varying their design parameters to obtain the optimal configurations under certain boundary conditions. A techno-economic analysis was performed using levelized cost of electricity and nighttime electricity fraction as variables for the representation. View this paper
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13 pages, 4509 KiB  
Article
Geometry, Mesh and Numerical Scheme Influencing the Simulation of a Pelton Jet with the OpenFOAM Toolbox
by Jean Decaix and Cécile Münch-Alligné
Energies 2022, 15(19), 7451; https://doi.org/10.3390/en15197451 - 10 Oct 2022
Cited by 3 | Viewed by 1717
Abstract
Hydropower is a key source of electricity production for allowing the integration of intermittent renewable energy resources. Among the various hydraulic power plants around the world, the ones equipped with Pelton turbines already provide large flexibility that is still enhanced with the development, [...] Read more.
Hydropower is a key source of electricity production for allowing the integration of intermittent renewable energy resources. Among the various hydraulic power plants around the world, the ones equipped with Pelton turbines already provide large flexibility that is still enhanced with the development, for instance, of the hydraulic short circuit operating mode. However, the knowledge of the flow inside Pelton turbines is still a challenging task, both numerically and experimentally, despite progress in the last two decades. One key feature of the Pelton efficiency is the jet quality, i.e., the jet velocity needs to be uniform, not perturbed by secondary flows and compact. The compactness of the jet is mainly dependent o nthe location of the jet detachment at the nozzle outlet, which is challenging for computational fluid dynamics simulations mainly due to numerical diffusion. Even if this point has already been mentioned in previous papers, the present paper focuses on all the parameters that can influence the jet detachment: the nozzle geometry, the mesh and the numerical scheme used to discretize the convective fluxes. The simulations of an existing Pelton injector are performed using the OpenFOAM toolbox. It is noticed that, in addition to the nozzle geometry and the mesh resolution at the nozzle outlet, the choice of the numerical schemes influences the jet detachment and, consequently, the jet diameter and discharge. The use of an anti-diffusive scheme such as the “SUPERBEE” limiter improves the prediction of the jet in accordance with the on-site measurements. Full article
(This article belongs to the Special Issue Experimental and Numerical Investigations of Hydraulic Machines)
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15 pages, 7362 KiB  
Article
Study on the Uniformity of Temperature Distribution of Transverse Flux Induction Heating Based on a New Magnetic Pole
by Huabin Song, Youhua Wang, Jiangpai Peng and Chengcheng Liu
Energies 2022, 15(19), 7450; https://doi.org/10.3390/en15197450 - 10 Oct 2022
Cited by 4 | Viewed by 1453
Abstract
A new magnetic pole is designed and proposed for the transverse flux induction heating (TFIH) device, since the TFIH device with the original magnetic pole has the deficiencies of uneven temperature distribution on the strip surface at the outlet of the heater and [...] Read more.
A new magnetic pole is designed and proposed for the transverse flux induction heating (TFIH) device, since the TFIH device with the original magnetic pole has the deficiencies of uneven temperature distribution on the strip surface at the outlet of the heater and large magnetic resistance of the alternating magnetic field through the magnetic circuit. Using the magnetic–thermal coupling calculation method proposed in this paper, the eddy current field and temperature field of the TFIH device with the original and new magnetic poles are calculated and analyzed under the same excitation. At the same time, the temperature distribution on the strip surface of the TFIH device with the new magnetic pole is calculated under different excitation parameters, and the magnitude and frequency are obtained when the uniformity of the temperature distribution is best. Full article
(This article belongs to the Section F: Electrical Engineering)
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28 pages, 8775 KiB  
Article
High-Order Band-Pass Active Damping Control and Predictive Control for Three-Phase Small-Film DC-Link Capacitor IPMSM Drive Systems
by Tian-Hua Liu, Sheng-Hsien Cheng and Chong-Yi Fan
Energies 2022, 15(19), 7449; https://doi.org/10.3390/en15197449 - 10 Oct 2022
Viewed by 1762
Abstract
Traditional three-phase rectifier DC-link inverters have been used in industry for more than 40 years. However, electrolytic capacitors, which are widely used in traditional inverters, have very large volumes and can only be used for five years. To solve this problem, a three-phase [...] Read more.
Traditional three-phase rectifier DC-link inverters have been used in industry for more than 40 years. However, electrolytic capacitors, which are widely used in traditional inverters, have very large volumes and can only be used for five years. To solve this problem, a three-phase small-film DC-link capacitor interior permanent-magnet synchronous motor drive system is investigated in this paper. This small-film capacitor not only has a longer life and smaller size than an electrolytic capacitor, but it can also improve the input harmonic currents and power factor on the grid side. A high-order band-pass filter active damping control is proposed here. In addition, a constrained predictive speed controller is designed to enhance the transient, load disturbance, and tracking speed performance. Furthermore, a constrained predictive current controller is implemented to reduce the three-phase harmonic currents of the motor. A digital signal processor, type TMS-320F-28035, manufactured by Texas Instruments, is employed as a control center to conduct the whole control algorithms. Several simulated and measured results are compared to demonstrate the practicability and correctness of the proposed control algorithms. Full article
(This article belongs to the Special Issue Design and Control of Electrical Motor Drives II)
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13 pages, 5243 KiB  
Article
Design of Battery Thermal Management System with Considering the Longitudinal and Transverse Temperature Difference
by Junhao Dong, Xipo Lu, Yang Sun, Vladislav Mitin, Huaping Xu and Wei Kong
Energies 2022, 15(19), 7448; https://doi.org/10.3390/en15197448 - 10 Oct 2022
Cited by 2 | Viewed by 1998
Abstract
For a bottom-liquid-cooled battery thermal management system (BTMS), the small contact area between the battery bottom and the cold plate leads to a large temperature difference in the battery height direction. In addition, the increase in coolant temperature from the inlet to the [...] Read more.
For a bottom-liquid-cooled battery thermal management system (BTMS), the small contact area between the battery bottom and the cold plate leads to a large temperature difference in the battery height direction. In addition, the increase in coolant temperature from the inlet to the outlet results in an excessive temperature difference in the battery module in the coolant flow direction. In order to solve the above issues, a wavy channel was first designed to strengthen the heat exchange between the battery bottom and the cold plate. The maximum battery module temperature for the wavy-channel design is 29.61 °C, which is a reduction of 1.75 °C compared to the straight-channel design. Then, the transverse temperature difference in the battery module was reduced by introducing a composite-channel design. Finally, on the basis of the composite channel, phase change material (PCM) was added to the battery’s top surface to reduce the temperature difference in the battery height direction. The results show that the maximum temperature and maximum temperature difference in the battery module of the composite-channel/PCM design proposed in this study are reduced by 6.8% and 41%, respectively, compared with the conventional straight-channel design. Full article
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16 pages, 7005 KiB  
Article
Effect of Water Injection on Turbine Inlet under Different Flight Conditions
by Jiamao Luo, Shengfang Huang, Shunhua Yang, Wanzhou Zhang and Zhongqiang Mu
Energies 2022, 15(19), 7447; https://doi.org/10.3390/en15197447 - 10 Oct 2022
Cited by 1 | Viewed by 1932
Abstract
Numerical simulations were conducted to research the pre-cooling effects of water injection on the turbine inlet of a turbine-based combined cycle (TBCC) engine under different flight conditions. Then, the performance of the water injection pre-compressor cooling (WIPCC) engine was calculated by mathematical modelling [...] Read more.
Numerical simulations were conducted to research the pre-cooling effects of water injection on the turbine inlet of a turbine-based combined cycle (TBCC) engine under different flight conditions. Then, the performance of the water injection pre-compressor cooling (WIPCC) engine was calculated by mathematical modelling with different water to air ratios (WAR). It was the first time that the mass injection field of the turbine inlet of a TBCC engine was simulated, and it was also the first time that the performance of a subcomponent turbine engine of a TBCC was assessed. The calculation results showed the relationship of the inlet temperature with respect to WAR, inlet length and flight Mach number. The strategy for inlet length and water mass flow was proposed in order to meet the requirements of pre-cooling. When the length of the turbine inlet was 10 times the diameter of the inlet exit, the air could be cooled by 167.5 K with WAR = 0.09. The highest evaporation ratio reached at 93%. Finally, the calculation results revealed the performance of the water-pre-cooled turbine engine, of which the flight envelope was expanded to Ma3.0 from Ma2.3 by pre-cooling. The engine thrust as well as the specific impulse were significantly improved. The thrust reached at 0.9 times the characteristic thrust meeting the TBCC mode transition requirement of thrust and working speed spectrum. Full article
(This article belongs to the Special Issue Heat and Thermal Fluid Flow for Advanced Aerospace Propulsion)
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19 pages, 6174 KiB  
Article
Comparative Analysis of Riser Base and Flowline Gas Injection on Vertical Gas-Liquid Two-Phase Flow
by Salem K. Brini Ahmed, Aliyu M. Aliyu, Yahaya D. Baba, Mukhtar Abdulkadir, Rahil Omar Abdulhadi, Liyun Lao and Hoi Yeung
Energies 2022, 15(19), 7446; https://doi.org/10.3390/en15197446 - 10 Oct 2022
Cited by 1 | Viewed by 1757
Abstract
Gas injection is a frequently used method for artificial lift and flow regime rectification in offshore production and transportation flowlines. The flow behaviour in such flowlines is complex and a better understanding of flow characteristics, such as flow patterns, void fraction/hold up distributions [...] Read more.
Gas injection is a frequently used method for artificial lift and flow regime rectification in offshore production and transportation flowlines. The flow behaviour in such flowlines is complex and a better understanding of flow characteristics, such as flow patterns, void fraction/hold up distributions and pressure gradient is always required for efficient and optimal design of downstream handling facilities. Injection method and location have been shown to strongly affect downstream fluid behaviour that can have important implications for pumping and downstream facility design, especially if the development length between pipeline and downstream facility is less than L/D = 50 as reported by many investigators. In this article, we provide the results of an experimental investigation into the effects of the gas injection position on the characteristics of the downstream upwards vertical gas flow using a vertical riser with an internal diameter of 52 mm and a length of 10.5 m. A horizontal 40-m-long section connected at the bottom provides options for riser base or horizontal flow line injection of gas. The flowline gas injection is performed 40 m upstream of the riser base. A 16 by 16 capacitance wire mesh sensor and a gamma densitometer were used to measure the gas-liquid phase cross-sectional distribution at the riser top. A detailed analysis of the flow characteristics is carried out based on the measurements. These include flow regimes, cross-sectional liquid holdup distributions and peaking patterns as well as analysis of the time series data. Our findings show that flow behaviours differences due to different gas injection locations were persisting after a development length of 180D in the riser. More specifically, core-peaking liquid holdup occurred at the lower gas injection rates through the flowline, while wall-peaking holdup profiles were established at the same flow conditions for riser base injection. Wall peaking was associated with dispersed bubbly flows and hence non-pulsating as against core-peaking was associated with Taylor bubbles and slug flows. Furthermore, it was found that the riser base injection generally produced lower holdups. It was noted that the circumferential injector used at the riser base promoted high void fraction and hence low liquid holdups. Due to the bubbly flow structure, the slip velocity is smaller than for larger cap bubbles and hence the void fraction is higher. The measurements and observations presented in the paper provides valuable knowledge on riser base/flowline gas introduction that can directly feed into the design of downstream facilities such as storage tanks, slug catchers and separators. Full article
(This article belongs to the Section A: Sustainable Energy)
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26 pages, 10556 KiB  
Article
Suppression of Wind Generator Speed Vibration Based on the Internal Model Control with Three Degrees of Freedom
by Chenyang Zhou and Yanxia Shen
Energies 2022, 15(19), 7445; https://doi.org/10.3390/en15197445 - 10 Oct 2022
Viewed by 1103
Abstract
When the wind power system is working in the maximum wind energy tracking area, or when its mechanical drivetrain system vibrates and the vibration frequency is relatively high, the system cannot suppress the speed vibration of the generator in the drivetrain system by [...] Read more.
When the wind power system is working in the maximum wind energy tracking area, or when its mechanical drivetrain system vibrates and the vibration frequency is relatively high, the system cannot suppress the speed vibration of the generator in the drivetrain system by adjusting the pitch angle. In this paper, a generator speed control system based on the three degrees of freedom internal model control (3-DOF-IMC) is established to control the generator speed. Thus, a scheme of using the feedback filter in the 3-DOF-IMC to suppress generator speed vibration caused by drivetrain shaft elasticity and gear clearance in the drivetrain system is proposed. Firstly, the vibration problem and waveform of the two-mass wind power drivetrain systems are discussed, and the generator’s vector control and speed control systems are analyzed. Secondly, the principle of the 3-DOF-IMC is described, and the influence of the three controllers on the speed tracking performance and anti-interference performance of the generator is discussed. The suppression ability of the feedback filter for different forms of disturbance signals is emphasized. Finally, the feedback filter controls the generator speed and eliminates the influence of drivetrain vibration on the generator speed. To verify the superiority of the proposed method, the vibration suppression effect, tracking performance and anti-interference performance of the proposed method are compared with the engineering design method (EDM) and conventional IMC (1-DOF-IMC) method. When the parameter α/β = 0.66, the generator speed amplitude overshoot of the proposed method is the same as the EDM. When α/β = 1, it is only 4% of the amplitude overshoot of the EDM. In addition, the tracking performance and anti-interference performance of the proposed method can be adjusted independently, and it is better than the EDM and the 1-DOF-IMC method. Full article
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15 pages, 4111 KiB  
Article
Possibilities of Using Zeolites Synthesized from Fly Ash in Adsorption Chillers
by Agata Mlonka-Mędrala, Tarikul Hasan, Wojciech Kalawa, Marcin Sowa, Karol Sztekler, Moises Luzia Pinto and Łukasz Mika
Energies 2022, 15(19), 7444; https://doi.org/10.3390/en15197444 - 10 Oct 2022
Cited by 5 | Viewed by 1450
Abstract
Adsorption chillers produce cold energy, using heat instead of electricity, thus reducing electrical energy consumption. A major industrial waste, fly ash, can be converted to zeolite and used in adsorption chillers as an adsorbent. In this research, three different types of zeolites were [...] Read more.
Adsorption chillers produce cold energy, using heat instead of electricity, thus reducing electrical energy consumption. A major industrial waste, fly ash, can be converted to zeolite and used in adsorption chillers as an adsorbent. In this research, three different types of zeolites were synthesised from fly ash via a hydrothermal reaction in an alkaline solution (NaOH). The obtained samples (Na-A zeolites) were modified with K2CO3 to increase the water adsorption capacity of these samples. Phase and morphology analyses shows that desired zeolites formed properly but other crystalline phases also exist along with nonporous amorphous phases. The determined specific surface areas for Na-A zeolite (12 h) and Na-A zeolite (24 h) are 45 m2/g and 185 m2/g respectively, while the specific surface area for synthesized 13X zeolite is almost negligible. Water-isotherm for each of these samples was measured. Considering the application of adsorption chillers, average adsorption capacity was very low, 1.73% and 1.27%, respectively, for the two most probable operating conditions for synthesized 13X zeolite, whereas no water was available for the evaporation from Na-A zeolite (12 h) and Na-A zeolite (24 h). This analysis implies that among the synthesized materials only 13X zeolite has a potential as an adsorber in sorption chillers. Full article
(This article belongs to the Special Issue Biomass and Waste Conversion: Latest Advances and Prospects)
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20 pages, 3893 KiB  
Article
Planning and Energy–Economy–Environment–Security Evaluation Methods for Municipal Energy Systems in China under Targets of Peak Carbon Emissions and Carbon Neutrality
by Weiwei Chen, Yibo Wang, Jia Zhang, Wei Dou and Yaxuan Jiao
Energies 2022, 15(19), 7443; https://doi.org/10.3390/en15197443 - 10 Oct 2022
Cited by 1 | Viewed by 1777
Abstract
In order to mitigate the negative effects of global climate change, the Chinese government has committed to achieving peak carbon emissions by 2030 and carbon neutrality by 2060. Since municipal cities are the bottom administrative level for drawing up development plans, it is [...] Read more.
In order to mitigate the negative effects of global climate change, the Chinese government has committed to achieving peak carbon emissions by 2030 and carbon neutrality by 2060. Since municipal cities are the bottom administrative level for drawing up development plans, it is necessary and important to conduct decarbonization pathway research on municipal energy systems (MESs). However, there is little research on decarbonization at the municipal level, and the impact of development paths in each forecast scenario is mostly based on expert evaluation and qualitative assessment. Therefore, this study established a complete decarbonization framework for MESs, including general research procedures, models, and a sustainable evaluation method. The models of energy consumption and carbon emission were adapted and improved for MESs. In order to quantitatively evaluate the energy system development for each scenario, we proposed an energy–economy–environment–security (3E–S) evaluation method, in which principal component analysis (PCA) was adopted for multi-criterion decision making. According to the analysis results of the case city in Guangdong, this evaluation method was proved to be an effective way to identify the factors that may influence coordinated development. By adjusting the relevant parameters and factors in the model, the optimal decarbonization pathway can be found to promote sustainable and coordinated development, thus helping government decision makers to quantitatively evaluate planning paths. Full article
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24 pages, 9504 KiB  
Article
ANFIS-Based Droop Control of an AC Microgrid System: Considering Intake of Water Treatment Plant
by C. Rohmingtluanga, Subir Datta, Nidul Sinha, Taha Selim Ustun and Akhtar Kalam
Energies 2022, 15(19), 7442; https://doi.org/10.3390/en15197442 - 10 Oct 2022
Cited by 2 | Viewed by 1878
Abstract
Provision of an efficient water supply system (WSS) is one of the top priorities of all municipals to ascertain adequate water supply to the city. Intake is the lifeline of the water supply system and largely effects the overall plant efficiency. The required [...] Read more.
Provision of an efficient water supply system (WSS) is one of the top priorities of all municipals to ascertain adequate water supply to the city. Intake is the lifeline of the water supply system and largely effects the overall plant efficiency. The required power supply is generally fed from the main grid, and a diesel generator is commonly used as a power backup source. This results in high pumping cost as well as high operational cost. Moreover, due to operation of motor pumps and other auxiliary loads, frequent maintenance is required. Therefore, to avoid various challenges and to efficiently operate the intake system, microgrid concept has been introduced in this paper. Various distributed generations (DGs) such as solar photovoltaic (PV), interior permanent magnet machine (IPM) wind turbine generator and Battery energy storage system (BESS) are incorporated in the microgrid system. Additionally, a new approach based on adaptive neuro-fuzzy inference system (ANFIS) is proposed, where P-f and Q-V droop is considered while training the ANFIS data; after successful training, the microgrid voltage and frequency are controlled as per system requirement. Simulation of the microgrid system shows good results and comparison with the generalized droop control (GDC) method is done using MATLAB/Simulink software. Full article
(This article belongs to the Special Issue Future Smart Grids with High Integrations of New Technologies)
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18 pages, 395 KiB  
Article
From Active Houses to Active Homes: Understanding Resident Experiences of Transformational Design and Social Innovation
by Fiona Shirani, Kate O’Sullivan, Rachel Hale, Nick Pidgeon and Karen Henwood
Energies 2022, 15(19), 7441; https://doi.org/10.3390/en15197441 - 10 Oct 2022
Cited by 3 | Viewed by 1624
Abstract
Active Buildings can contribute to efforts to address decarbonisation and climate change targets, and have the potential to support social aspirations for technical and infrastructural change. Yet achieving such goals is challenging. Active Homes as a type of Active Building represent a particularly [...] Read more.
Active Buildings can contribute to efforts to address decarbonisation and climate change targets, and have the potential to support social aspirations for technical and infrastructural change. Yet achieving such goals is challenging. Active Homes as a type of Active Building represent a particularly interesting prospect; altering how energy is produced, distributed, and consumed, but also how homes are designed, constructed, and lived in are studied. Active Homes are designed with expectations of how residents will engage with them, but residents do not always live in the homes in ways envisaged by developers. Hence, there is a risk that the homes will not be experienced as comfortable living environments, or otherwise perform as anticipated. Thus, understanding resident perspectives is crucial to the successful wider rollout of Active Homes. We draw on social science research with designers, developers, and residents to explore expectations of life in an Active Home. Our longitudinal research design enables us to contrast early expectations with post-occupancy experiences, elucidating what residents consider to be successful aspects of Active Home developments. Our research reveals instances where expectations remain unfulfilled, or where living in the homes has been experienced as challenging or disruptive. In highlighting such insights, we offer recommendations relevant for future developments. Full article
(This article belongs to the Special Issue Active Buildings: From Theory to Practice)
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16 pages, 3743 KiB  
Article
Sorption and Spatial Distribution of 137Cs, 90Sr and 241Am on Mineral Phases of Fractured Rocks of Nizhnekansky Granitoid Massif
by Anastasiya A. Rodionova, Vladimir G. Petrov, Irina E. Vlasova, Konstantin B. Rozov, Iurii M. Nevolin, Vasiliy O. Yapaskurt, Vyacheslav G. Rumynin and Stepan N. Kalmykov
Energies 2022, 15(19), 7440; https://doi.org/10.3390/en15197440 - 10 Oct 2022
Viewed by 1486
Abstract
The sorption behavior and spatial microdistribution of Cs-137, Sr-90 and Am-241 onto the surface of a fractured rock sample from the R-11 borehole of the exocontact zone of the Nizhnekansky granitoid massif were studied. The sorption efficiency of the fractured sample increases in [...] Read more.
The sorption behavior and spatial microdistribution of Cs-137, Sr-90 and Am-241 onto the surface of a fractured rock sample from the R-11 borehole of the exocontact zone of the Nizhnekansky granitoid massif were studied. The sorption efficiency of the fractured sample increases in the row of Sr < Cs < Am, where americium is the most retained radionuclide. Based on the image processing of radiograms and scanning electron microscopy data, the mineral relative sorption efficiency (RSE) values were determined to quantify the contribution of the mineral phases of the fractured sample to radionuclide retention. It was established that cesium and strontium are predominantly retained in cracks filled with secondary mineral chlorite. Zeolite is a less effective sorbent with respect to cesium and strontium. Americium sorption is uniform over the whole surface of the fractured sample, with close RSE values for all mineral phases (RSE ~1). The behavior of cesium in heterogeneous and monomineral systems of crushed mineral phases of quartz, biotite and zeolite NaA imitating minerals of the fractured rock sample R-11 was determined. It was shown that the fraction of the sorbed cesium in a heterogeneous system of two mineral phases—biotite and quartz—was larger than the sum of sorption values for the same separated mineral phases. Based on the models of radionuclide sorption on illite–smectite minerals, it was able to estimate the depth of the penetration of solution into the fractured rock sample R-11. The variations of penetration depths for solutions of specific radionuclide into the fractured rock sample were established. Full article
(This article belongs to the Section A: Sustainable Energy)
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19 pages, 4485 KiB  
Article
Energetic and Economic Performances of the Energy Community of Magliano Alpi after One Year of Piloting
by Emilio Ghiani, Riccardo Trevisan, Gian Luca Rosetti, Sergio Olivero and Luca Barbero
Energies 2022, 15(19), 7439; https://doi.org/10.3390/en15197439 - 10 Oct 2022
Cited by 13 | Viewed by 2241
Abstract
Italy’s first renewable energy community, located in the municipality of Magliano Alpi, was established under Italian Law 8/2020 on Energy Communities in December 2020. The community is composed of eight stakeholders and involves, in addition to public buildings in the municipality of Magliano [...] Read more.
Italy’s first renewable energy community, located in the municipality of Magliano Alpi, was established under Italian Law 8/2020 on Energy Communities in December 2020. The community is composed of eight stakeholders and involves, in addition to public buildings in the municipality of Magliano Alpi, some residential users and small and medium-sized enterprises, realizing public–private cooperation aimed at reducing energy dependence on the public grid and, at the same time, contributing to the decarbonization of the energy sector. This article provides an analysis of the economic and energy performance during the first year of renewable community piloting. The study analyzes data collected with the community energy management system and introduces a number of key performance indices useful for evaluating further development and optimization options. Full article
(This article belongs to the Special Issue Energy Communities Implementation)
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21 pages, 5060 KiB  
Article
Effect of Cell Electrical Mismatch on Output of Crystalline Photovoltaic Modules
by Somin Park, Younghyun Cho, Seulki Kim, Koo Lee and Junsin Yi
Energies 2022, 15(19), 7438; https://doi.org/10.3390/en15197438 - 10 Oct 2022
Cited by 3 | Viewed by 1313
Abstract
The importance of energy supply and demand has been emphasized over the past few years. Renewable energy without regional bias continues to attract attention. The improvement of the economic feasibility of renewable energy leads to the expansion of the supply, and the global [...] Read more.
The importance of energy supply and demand has been emphasized over the past few years. Renewable energy without regional bias continues to attract attention. The improvement of the economic feasibility of renewable energy leads to the expansion of the supply, and the global supply of solar modules is also rapidly increasing. Recently, the price of polysilicon for solar modules is also rising significantly. Interest in recycling waste modules is also increasing. However, the development of cost-effective treatment technology for solar modules that have reached the end of their commercial useful life is still insufficient. We are going to propose the standards necessary to restore and reuse so-called waste solar modules in a more eco-friendly and economical way. A crystalline solar module is an aggregate of individual solar cells. The technology is stable and has good durability. The efficiency of crystalline solar cells has dramatically improved in recent decades. The grade of cell that was mainly used two or three years ago will be discontinued soon. Therefore, electrical mismatch of the cells occurs while repairing an old-manufactured module with recently produced cells. In this paper, we experimentally verify how the increase in cell mismatch affects the module output. We intend to suggest the range of acceptable mismatches by analyzing the tendency. First of all, we repaired and restored the module in which all the existing cells were discontinued after about 10 years of production. The replacement cell had 16.94% higher output than the existing cells. After restoring the module, it was confirmed that the electrical mismatch loss of the cell in this range was very small, about 1.69%. Second, the mismatch loss was confirmed by manufacturing a module by mixing the two cells. The difference in output between the two cells was 5.56%. The mismatch loss compared to the predicted value based on the output of the individual cell and the actual value was very small, less than 0.76%. The long-term reliability results through the DH 1000 hr experiment on the sample that simulated the situation of repair, and the rest of the samples also showed a decrease in output up to 1.13%, which was not a problem. Finally, we hypothesized that a series-connected array should be constructed by reusing modules with different output classes. By cutting into 1/4, 1/3, and 1/2 of cells of the same grade, various unit module samples composed of 0.5 cells to 2.0 cells were manufactured and the output was measured. Electrical mismatch loss was tested by serially combining each unit module at various mismatch ratios. It was confirmed that the output loss in the three or more samples similarly exceeds about 10% with the mismatch ratio of 50% as the starting point. In the previous study, when the mismatch ratio was 70%, the output loss was about 17.98%. The output loss was 18.30% at 86.57%, 17.33% at 77.33%, and 14.37% at 75%. Considering that it is a value measured in a wide range, it is a result that is quite consistent with the results of previous studies. When the cell output difference was less than 50%, the electrical mismatch of the cell had no significant effect on the module output. When it exceeds that, a sudden output loss of 10% or more begins to occur. Consequently, the mismatch range of compatible cells should be less than 50%. If it exceeds that, not only output loss but also safety problems may occur due to heat generation. We can offer a range of interchangeable cell output power when crystalline solar modules are repaired and reused. By recycling modules with different outputs, you can provide a standard for those who want to use it by composing an array. By extending the lifespan of a solar module once used, it is expected that the generation of waste can be reduced from environmental point of view and the resources required to manufacture a new module can be saved from the resource-circulation point of view. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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26 pages, 1982 KiB  
Article
Multi-Step Ahead Natural Gas Consumption Forecasting Based on a Hybrid Model: Case Studies in The Netherlands and the United Kingdom
by Longfeng Zhang, Xin Ma, Hui Zhang, Gaoxun Zhang and Peng Zhang
Energies 2022, 15(19), 7437; https://doi.org/10.3390/en15197437 - 10 Oct 2022
Cited by 1 | Viewed by 1610
Abstract
With worldwide activities of carbon neutrality, clean energy is playing an important role these days. Natural gas (NG) is one of the most efficient clean energies with less harmful emissions and abundant reservoirs. This work aims at developing a swarm intelligence-based tool for [...] Read more.
With worldwide activities of carbon neutrality, clean energy is playing an important role these days. Natural gas (NG) is one of the most efficient clean energies with less harmful emissions and abundant reservoirs. This work aims at developing a swarm intelligence-based tool for NG forecasting to make more convincing projections of future energy consumption, combining Extreme Gradient Boosting (XGBoost) and the Salp Swarm Algorithm (SSA). The XGBoost is used as the core model in a nonlinear auto-regression procedure to make multi-step ahead forecasting. A cross-validation scheme is adopted to build a nonlinear programming problem for optimizing the most sensitive hyperparameters of the XGBoost, and then the nonlinear optimization is solved by the SSA. Case studies of forecasting the Natural gas consumption (NGC) in the United Kingdom (UK) and Netherlands are presented to illustrate the performance of the proposed hybrid model in comparison with five other intelligence optimization algorithms and two other decision tree-based models (15 hybrid schemes in total) in 6 subcases with different forecasting steps and time lags. The results show that the SSA outperforms the other 5 algorithms in searching the optimal parameters of XGBoost and the hybrid model outperforms all the other 15 hybrid models in all the subcases with average MAPE 4.9828% in NGC forecasting of UK and 9.0547% in NGC forecasting of Netherlands, respectively. Detailed analysis of the performance and properties of the proposed model is also summarized in this work, which indicates it has high potential in NGC forecasting and can be expected to be used in a wider range of applications in the future. Full article
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17 pages, 5205 KiB  
Article
Modeling and Control of a Hybrid Multi DOF Motor for a Tilted Rotating System
by Hyun-Jong Park and Sung-Chul Go
Energies 2022, 15(19), 7436; https://doi.org/10.3390/en15197436 - 10 Oct 2022
Cited by 1 | Viewed by 1635
Abstract
This paper presents the design, modeling, and control of a hybrid multi-degree-of-freedom motor (HMDOF motor) that can be applied to unmanned aerial vehicles, such as drones. The HMDOF motor has a rotating motor and tilting motors separately and enables multi-DOF movement by driving [...] Read more.
This paper presents the design, modeling, and control of a hybrid multi-degree-of-freedom motor (HMDOF motor) that can be applied to unmanned aerial vehicles, such as drones. The HMDOF motor has a rotating motor and tilting motors separately and enables multi-DOF movement by driving each motor. In addition, owing to its structural characteristics, it is designed to allow a 3- or 6-DOF movement in only one motor. In this study, the control performance of an HMDOF motor was verified using simulated and experimental results. The position control performance for the rotation speed of the rotating motor was verified, and the control performance of the motor under the speed of the rotating motor and disturbance on tilting motors were analyzed. Full article
(This article belongs to the Special Issue Design, Analysis and Control of Permanent Magnet Machines)
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22 pages, 2029 KiB  
Article
Sustainable Transition from Fossil Fuel to Geothermal Energy: A Multi-Level Perspective Approach
by Satya Widya Yudha, Benny Tjahjono and Philip Longhurst
Energies 2022, 15(19), 7435; https://doi.org/10.3390/en15197435 - 10 Oct 2022
Cited by 2 | Viewed by 2331
Abstract
Indonesia is currently undergoing the energy transition from heavily fossil fuel-dependent energy to cleaner sources of energy in order to achieve its net-zero emissions by 2060. In addition to reducing fossil fuel dependency, as one of the countries with the most geothermal reserves, [...] Read more.
Indonesia is currently undergoing the energy transition from heavily fossil fuel-dependent energy to cleaner sources of energy in order to achieve its net-zero emissions by 2060. In addition to reducing fossil fuel dependency, as one of the countries with the most geothermal reserves, the optimization of geothermal energy in Indonesia could be key to facilitating the energy transition. The objective of this paper is to elaborate on the transition process, which incorporates the destabilization of fossil fuel and the growth of geothermal energy, by analyzing the impact of both exogenous and endogenous factors on the supply chain structures of both sectors. This study employs workshop involving geothermal stakeholders in Indonesia, combined with the application of the Multi-Level Perspective (MLP) framework as the theoretical lens. The study found that energy demand, environmental awareness, energy regulations, energy supply chain, and geothermal potential breakthroughs are important aspects pertinent to the MLP components, namely the socio-technical landscape, socio-technical regime and niche innovations. The socio-technical landscapes are exogenous factors that pressurize the energy sector regime allowing the niche innovation, in the form of geothermal innovation, to penetrate the fossil fuel regime, allowing it to transition to a geothermal regime. The transition pathways include several measures that could break down the fossil fuel and build up geothermal energy, through a number of schemes and incentives. Full article
(This article belongs to the Special Issue New Challenges in the Utilization of Underground Energy and Space)
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26 pages, 7070 KiB  
Article
A Hybrid Model for Electricity Demand Forecast Using Improved Ensemble Empirical Mode Decomposition and Recurrent Neural Networks with ERA5 Climate Variables
by Karodine Chreng, Han Soo Lee and Soklin Tuy
Energies 2022, 15(19), 7434; https://doi.org/10.3390/en15197434 - 10 Oct 2022
Cited by 3 | Viewed by 1823
Abstract
By conserving natural resources and reducing the consumption of fossil fuels, sustainable energy development plays a crucial role in energy planning. Specifically, demand-side planning must be researched and anticipated based on electricity consumption at the grounded level. Due to the global warming crisis, [...] Read more.
By conserving natural resources and reducing the consumption of fossil fuels, sustainable energy development plays a crucial role in energy planning. Specifically, demand-side planning must be researched and anticipated based on electricity consumption at the grounded level. Due to the global warming crisis, atmospheric conditions are among the most influential components that have altered electricity consumption patterns. In this study, 66 climate variables from the ERA5 reanalysis and the observed power demand at four grid substations (GSs) in Cambodia were examined using recurrent neural networks (RNNs). Using the cross-correlation function between power demand and each climate variable, statistically significant climate variables were sorted out. In addition, a wide range of feedback delays (FDs) was generated from the data on power demand and defined using 95% confidence intervals. The combination of the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) technique with a nonlinear autoregressive neural network with exogenous inputs (NARX) and a nonlinear autoregressive neural network (NAR) produced a hybrid electricity forecasting model. The data were decomposed into the intrinsic mode functions (IMFs) and were then used as inputs in optimized NARX and NAR models. The performance of the various benchmarked models was analyzed and compared using mainly statistical indicators such as the normalized root mean square error (NMSE) and the coefficient of determination (R2). The hybrid models perform exceptionally well in predicting electricity demand, and the ICEEMDAN-NARX hybrid model with correlated climate variables performs the best among the tested experiments as a useful prediction tool. Full article
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19 pages, 1464 KiB  
Article
On the Possibility of Cleaning Producer Gas Laden with Large Quantities of Tars through Using a Simple Fixed-Bed Activated Carbon Adsorption Process
by Mateusz Kochel, Mateusz Szul, Tomasz Iluk and Jan Najser
Energies 2022, 15(19), 7433; https://doi.org/10.3390/en15197433 - 10 Oct 2022
Cited by 2 | Viewed by 1509
Abstract
The study presents the results of research on using fixed-bed, activated carbon (AC) adsorbers in the cleaning of heavily tar-laden producer gas from the gasification of biomass. The efficiency of removal of organic compounds as well as the remaining adsorption capacity of the [...] Read more.
The study presents the results of research on using fixed-bed, activated carbon (AC) adsorbers in the cleaning of heavily tar-laden producer gas from the gasification of biomass. The efficiency of removal of organic compounds as well as the remaining adsorption capacity of the bed were determined using a spectrum of commonly applied diagnostic methods, including qualitative and quantitative analyses of the adsorbed compounds and changes in the pore volume of the bed material (IN, MN). The authors compare these lab quantifications with a simple technique which is based on the analysis of the changes in the position of temperature front in the bed. The main benefit of the latter is the possibility of performing the diagnostics of the bed “online” and using low-cost temperature measurements. The test was performed using a commercially available AC Desotec AIRPEL 10-3 and real producer gas obtained through the gasification of alder chips. For tar, VOC and C2–C5 compounds, the removal efficiencies reached respectively 74.5%-wt., 52.8%-wt., and 85.5%-wt. Obtained results indicate that depending on the final application of the gas, the use of dry adsorption systems is an interesting alternative to the well-established but complicated, cumbersome, and costly wet scrubbers. Moreover, a concept for in situ regeneration of the adsorbent, coupled with direct reforming of the tars, is presented and discussed. Full article
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23 pages, 6822 KiB  
Article
Active Defense Research against False Data Injection Attacks of Power CPS Based on Data-Driven Algorithms
by Xiaoyong Bo, Zhaoyang Qu, Lei Wang, Yunchang Dong, Zhenming Zhang and Da Wang
Energies 2022, 15(19), 7432; https://doi.org/10.3390/en15197432 - 10 Oct 2022
Cited by 5 | Viewed by 1790
Abstract
The terminal equipment interconnection and the network communication environment are complex in power cyber–physical systems (CPS), and the frequent interaction between the information and energy flows aggravates the risk of false data injection attacks (FDIAs) in the power grid. This paper proposes an [...] Read more.
The terminal equipment interconnection and the network communication environment are complex in power cyber–physical systems (CPS), and the frequent interaction between the information and energy flows aggravates the risk of false data injection attacks (FDIAs) in the power grid. This paper proposes an active defense framework against FDIAs of power CPS based on data-driven algorithms in order to ensure that FDIAs can be efficiently detected and processed in real-time during power grid operation. First, the data transmission scenario and false data injection forms of power CPS were analyzed, and the FDIA mathematical model was expounded. Then, from a data-driven perspective, the algorithm improvement and process design were carried out for the three key links of data enhancement, attack detection, and data reconstruction. Finally, an active defense framework against FDIAs was proposed. The example analysis verified that the method proposed in this paper could effectively detect FDIAs and perform data reconstruction, providing a new idea for the active defense against FDIAs of power CPS. Full article
(This article belongs to the Special Issue Volume II: Situation Awareness for Smart Distribution Systems)
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26 pages, 13033 KiB  
Article
Applicability of Wake Models to Predictions of Turbine-Induced Velocity Deficit and Wind Farm Power Generation
by Dongqin Zhang, Yang Liang, Chao Li, Yiqing Xiao and Gang Hu
Energies 2022, 15(19), 7431; https://doi.org/10.3390/en15197431 - 10 Oct 2022
Cited by 3 | Viewed by 1648
Abstract
Turbine-induced velocity deficit is the main reason to reduce wind farm power generation and increase the fatigue loadings. It is meaningful to investigate turbine-induced wake structures by a simple and accurate method. In this study, a series of single turbine wake models are [...] Read more.
Turbine-induced velocity deficit is the main reason to reduce wind farm power generation and increase the fatigue loadings. It is meaningful to investigate turbine-induced wake structures by a simple and accurate method. In this study, a series of single turbine wake models are proposed by combining different spanwise distributions and wake boundary expansion models. It is found that several combined wake models with high hit rates are more accurate and universal. Subsequently, the wake models for multiple wind turbines are also investigated by considering the combined wake models for single turbine and proper superposition approaches. Several excellent plans are provided where the velocity, turbulence intensity, and wind power generation for multiple wind turbines can be accurately evaluated. Finally, effects of thrust coefficient and ambient turbulence intensity are studied. In summary, the combined wake models for both single and multiple wind turbines are proposed and validated, enhancing the precision of wind farm layout optimization will be helped by using these wake models. Full article
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14 pages, 2223 KiB  
Article
Biometric Authentication-Based Intrusion Detection Using Artificial Intelligence Internet of Things in Smart City
by C. Annadurai, I. Nelson, K. Nirmala Devi, R. Manikandan, N. Z. Jhanjhi, Mehedi Masud and Abdullah Sheikh
Energies 2022, 15(19), 7430; https://doi.org/10.3390/en15197430 - 10 Oct 2022
Cited by 27 | Viewed by 3203
Abstract
Nowadays, there is a growing demand for information security and security rules all across the world. Intrusion detection (ID) is a critical technique for detecting dangers in a network during data transmission. Artificial Intelligence (AI) methods support the Internet of Things (IoT) and [...] Read more.
Nowadays, there is a growing demand for information security and security rules all across the world. Intrusion detection (ID) is a critical technique for detecting dangers in a network during data transmission. Artificial Intelligence (AI) methods support the Internet of Things (IoT) and smart cities by creating gadgets replicating intelligent behavior and enabling decision making with little or no human intervention. This research proposes novel technique for secure data transmission and detecting an intruder in a biometric authentication system by feature extraction with classification. Here, an intruder is detected by collecting the biometric database of the smart building based on the IoT. These biometric data are processed for noise removal, smoothening, and normalization. The processed data features are extracted using the kernel-based principal component analysis (KPCA). Then, the processed features are classified using the convolutional VGG−16 Net architecture. Then, the entire network is secured using a deterministic trust transfer protocol (DTTP). The suggested technique’s performance was calculated utilizing several measures, such as the accuracy, f-score, precision, recall, and RMSE. The simulation results revealed that the proposed method provides better intrusion detection outcomes. Full article
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18 pages, 894 KiB  
Review
Review of Renewable Energy Subsidy System in China
by Dongdong Song, Boya Jia and Hongtao Jiao
Energies 2022, 15(19), 7429; https://doi.org/10.3390/en15197429 - 10 Oct 2022
Cited by 13 | Viewed by 2863
Abstract
In the context of the ‘carbon peaking and carbon neutrality goals’, renewable energy, with its clean and low-carbon characteristics, has become one of the key driving forces for sustainable development in China. However, the inherent disadvantages of the renewable energy industry, such as [...] Read more.
In the context of the ‘carbon peaking and carbon neutrality goals’, renewable energy, with its clean and low-carbon characteristics, has become one of the key driving forces for sustainable development in China. However, the inherent disadvantages of the renewable energy industry, such as high initial investment costs, technical difficulties, and slow returns on investment, make it difficult to compete with traditional fossil energy sources in the market economy at the initial stage of its establishment. Therefore, after considering the environmental and ecological value, economic value, and industrial growth dilemma brought by the development of renewable energy industry, subsidies as a governmental incentive measure were created to support the development and growth of the renewable energy industry. At present, there are many problems with China’s renewable energy subsidy policy in practice, such as fragmented institutional policies, lack of procedural regulations, and lagging subsidy funds. The excellent legislative practice experience of foreign countries can be borrowed by China to make up for the corresponding loopholes and, on the basis of fully examining the specific conditions of China, to promote the progressive reform of China’s renewable energy subsidy system; form a trinity system of law, general strategy, and specific policies; strengthen collaboration; and enhance its scientific level. At the same time, China can actively broaden the sources of subsidy funds, explore diversified financing methods, further standardize the subsidy procedures, strengthen the supervision in implementation, and enhance the efficiency of the utilization of funds, so as to enhance the legalization of the subsidy system. Full article
(This article belongs to the Section C: Energy Economics and Policy)
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17 pages, 1993 KiB  
Article
Forest Management Communities’ Participation in Bioenergy Production Initiatives: A Case Study for Galicia (Spain)
by Raquel Fernández-González, Félix Puime Guillén, Otilia Manta, Simona Andreea Apostu and Valentina Vasile
Energies 2022, 15(19), 7428; https://doi.org/10.3390/en15197428 - 10 Oct 2022
Cited by 3 | Viewed by 2141
Abstract
Bioenergy is the form of clean energy with the greatest potential for growth in Spain, especially in those regions with a large forest area and a high potential for the utilization of forest resources for energy purposes. This is the case in Galicia [...] Read more.
Bioenergy is the form of clean energy with the greatest potential for growth in Spain, especially in those regions with a large forest area and a high potential for the utilization of forest resources for energy purposes. This is the case in Galicia (a region located in northwestern Spain), where the communal management of forest resources is widespread. Within this type of management, there is a pioneering case study in which biomass energy use activities have been initiated through an international project. The possible success of this project is of great importance since it could represent an alternative to the main energy activity in the common management of forests: the production of wind energy. In recent years, and with a special increase in 2022, Galician public opinion has expressed its opposition to the implementation of new wind farms in its forests. The aim of this article is to analyze whether or not it is profitable for forest management communities to participate in bioenergy initiatives, which is a novel analysis of the Galician geographical area. For this purpose, the main economic and financial variables of the Galician forest management communities participating in the bioenergy project, SilvaPlus Project, have been analyzed, before and during their participation in the project. In addition, a financial comparison is also made with a group of Galician forest management communities without the energy use of their resources. The evolution of the relevant variables, analyzed between 2011 and 2020, shows a generally positive trend in the values of the forest communities participating in the bioenergy generation project, resulting in a positive experience, both environmentally and financially, for the forest community. Full article
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19 pages, 692 KiB  
Review
Hydropower in the Energy Market in Poland and the Baltic States in the Light of the Challenges of Sustainable Development-An Overview of the Current State and Development Potential
by Ewa Chomać-Pierzecka, Andrzej Kokiel, Joanna Rogozińska-Mitrut, Anna Sobczak, Dariusz Soboń and Jacek Stasiak
Energies 2022, 15(19), 7427; https://doi.org/10.3390/en15197427 - 10 Oct 2022
Cited by 24 | Viewed by 2370
Abstract
The energy crisis is affecting a number of countries, but particularly those that are heavily dependent on the traditional energy generation formula (e.g., Poland), as well as those neighbouring the territory of the ongoing war in Ukraine, i.e., Poland, Lithuania, Latvia and Estonia. [...] Read more.
The energy crisis is affecting a number of countries, but particularly those that are heavily dependent on the traditional energy generation formula (e.g., Poland), as well as those neighbouring the territory of the ongoing war in Ukraine, i.e., Poland, Lithuania, Latvia and Estonia. With this in mind, the authors of this study decided to explore the issue of water energy as a source of green (cheap and environmentally safe) energy in these countries. The main objective of the paper is to review the available literature, which is needed to identify the role hydropower plays in energy security and energy transition in these energy markets. This paper is based on a review and critical appraisal of the available literature and studies together with an inference. The structure of the paper consists of an introduction, the main part of the review and conclusions. The geopolitical location and socio-economic conditions of the adopted set of countries, form the basis of the review of the existing literature on the theme explored and the substantive inference. The main findings of this review indicate that the literature is most strongly focused on the overall assessment of the energy transition of the adopted countries for review, where the hydropower thread is most often taken up as one source of renewable energy supply. Hydropower, due to its relatively low share in the energy systems of the adopted set of countries, is, according to the authors, insufficiently explored. The most significant gap relates to the aspect of the potential for hydropower development in these areas, considering both the construction of new hydropower plants and opportunities signalled in the literature for the modernisation or restoration of existing ones. In this respect, the need for analyses (studies and simulations) of hydropower development, considering the economic benefits associated with their development juxtaposed with the safety dimension of this course of action for the environment (analysis and assessment of environmental costs) is indicated, which is the main recommendation of the review. Full article
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18 pages, 1374 KiB  
Article
Multiagent Reinforcement Learning Based on Fusion-Multiactor-Attention-Critic for Multiple-Unmanned-Aerial-Vehicle Navigation Control
by Sangwoo Jeon, Hoeun Lee, Vishnu Kumar Kaliappan, Tuan Anh Nguyen, Hyungeun Jo, Hyeonseo Cho and Dugki Min
Energies 2022, 15(19), 7426; https://doi.org/10.3390/en15197426 - 10 Oct 2022
Cited by 4 | Viewed by 2595
Abstract
The proliferation of unmanned aerial vehicles (UAVs) has spawned a variety of intelligent services, where efficient coordination plays a significant role in increasing the effectiveness of cooperative execution. However, due to the limited operational time and range of UAVs, achieving highly efficient coordinated [...] Read more.
The proliferation of unmanned aerial vehicles (UAVs) has spawned a variety of intelligent services, where efficient coordination plays a significant role in increasing the effectiveness of cooperative execution. However, due to the limited operational time and range of UAVs, achieving highly efficient coordinated actions is difficult, particularly in unknown dynamic environments. This paper proposes a multiagent deep reinforcement learning (MADRL)-based fusion-multiactor-attention-critic (F-MAAC) model for multiple UAVs’ energy-efficient cooperative navigation control. The proposed model is built on the multiactor-attention-critic (MAAC) model, which offers two significant advances. The first is the sensor fusion layer, which enables the actor network to utilize all required sensor information effectively. Next, a layer that computes the dissimilarity weights of different agents is added to compensate for the information lost through the attention layer of the MAAC model. We utilize the UAV LDS (logistic delivery service) environment created by the Unity engine to train the proposed model and verify its energy efficiency. The feature that measures the total distance traveled by the UAVs is incorporated with the UAV LDS environment to validate the energy efficiency. To demonstrate the performance of the proposed model, the F-MAAC model is compared with several conventional reinforcement learning models with two use cases. First, we compare the F-MAAC model to the DDPG, MADDPG, and MAAC models based on the mean episode rewards for 20k episodes of training. The two top-performing models (F-MAAC and MAAC) are then chosen and retrained for 150k episodes. Our study determines the total amount of deliveries done within the same period and the total amount done within the same distance to represent energy efficiency. According to our simulation results, the F-MAAC model outperforms the MAAC model, making 38% more deliveries in 3000 time steps and 30% more deliveries per 1000 m of distance traveled. Full article
(This article belongs to the Special Issue Energy Efficiency in Wireless Networks)
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22 pages, 1851 KiB  
Article
Νarrow Row Spacing and Cover Crops to Suppress Weeds and Improve Sulla (Hedysarum coronarium L.) Biomass Production
by Ioannis Gazoulis, Panagiotis Kanatas, Nikolaos Antonopoulos, Alexandros Tataridas and Ilias Travlos
Energies 2022, 15(19), 7425; https://doi.org/10.3390/en15197425 - 10 Oct 2022
Cited by 4 | Viewed by 1697
Abstract
Sulla (Hedysarum coronarium L.) is a new candidate crop for biofuel production. A field trial was conducted in 2018–2020 in Pyrgos, Greece, and repeated in 2019–2021 to evaluate different row spacings and cover crops for weed management in sulla in a two-factor [...] Read more.
Sulla (Hedysarum coronarium L.) is a new candidate crop for biofuel production. A field trial was conducted in 2018–2020 in Pyrgos, Greece, and repeated in 2019–2021 to evaluate different row spacings and cover crops for weed management in sulla in a two-factor randomized complete block design (RCBD) with four replications. Four row spacings, namely 76-cm, 51-cm, 38-cm, and 19-cm, were assigned to the main plots. Three cover crops, namely farro wheat (Triticum turgidum subsp. dicoccum (Schrank ex Schübler) Thell.), common vetch (Vicia sativa L.), white mustard (Sinapis alba L.), and an untreated control, were assigned to the subplots. In the first year of sulla growth, weed biomass, sulla stem, and total dry matter yield (DMY) were affected by growing cycles (p-value ≤ 0.05). The 19- and 38-cm row spacings resulted in the lowest weed biomass and the highest stem and total sulla DMY in the first year of sulla growth. White mustard was the most weed-suppressive cover crop in both years and growing cycles followed by farro heat. The highest stem DMY was observed in subplots with white mustard in both years. The combination of 38 cm row spacing and white mustard as a cover crop resulted in the highest cumulative two-year sulla DMY (18.9 t ha−1). Further case studies are needed to evaluate more cultural practices for weed management in sulla and other major biomass crops under different soil and climatic conditions. Full article
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35 pages, 6080 KiB  
Review
Energy Harvesting from Fluid Flow Using Piezoelectric Materials: A Review
by Areeba Naqvi, Ahsan Ali, Wael A. Altabey and Sallam A. Kouritem
Energies 2022, 15(19), 7424; https://doi.org/10.3390/en15197424 - 10 Oct 2022
Cited by 38 | Viewed by 8130
Abstract
Energy harvesting from piezoelectric materials is quite common and has been studied for the past few decades, but, recently, there have been a lot of new advancements in harnessing electrical energy via piezoelectric materials. In this regard, several studies were carried out in [...] Read more.
Energy harvesting from piezoelectric materials is quite common and has been studied for the past few decades, but, recently, there have been a lot of new advancements in harnessing electrical energy via piezoelectric materials. In this regard, several studies were carried out in electrochemistry and fluid flow. Furthermore, consideration of productive and valuable resources is important to meet the needs of power generation. For this purpose, energy harvesting from fluids such as wind and water is significant and must be implemented on a large scale. So, developing self-powering devices can resolve the problem like that, and piezoelectric materials are gaining interest day by day because these materials help in energy generation. This review paper discusses different techniques for harnessing energy from fluid flows using piezoelectric materials. In addition, various vibration-based energy-harvesting mechanisms for improving the efficiency of piezoelectric energy harvesters have also been investigated and their opportunities and challenges identified. Full article
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25 pages, 4004 KiB  
Article
An Efficient Method Combined Data-Driven for Detecting Electricity Theft with Stacking Structure Based on Grey Relation Analysis
by Rui Xia, Yunpeng Gao, Yanqing Zhu, Dexi Gu and Jiangzhao Wang
Energies 2022, 15(19), 7423; https://doi.org/10.3390/en15197423 - 10 Oct 2022
Cited by 9 | Viewed by 1672
Abstract
Nowadays, electricity theft has been a major problem worldwide. Although many single-classification algorithms or an ensemble of single learners (i.e., homogeneous ensemble learning) have proven able to automatically identify suspicious customers in recent years, after the accuracy of these methods reaches a certain [...] Read more.
Nowadays, electricity theft has been a major problem worldwide. Although many single-classification algorithms or an ensemble of single learners (i.e., homogeneous ensemble learning) have proven able to automatically identify suspicious customers in recent years, after the accuracy of these methods reaches a certain level, it still cannot be improved even if it continues to be optimized. To break through this bottleneck, a heterogeneous ensemble learning method with stacking integrated structure of different strong individual learners for detection of electricity theft is presented in this paper. Firstly, we use the grey relation analysis (GRA) method to select the heterogeneous strong classifier combination of LG + LSTM + KNN as the base model layer of stacking structure based on the principle of the highest comprehensive evaluation index value. Secondly, the support vector machine (SVM) model with relatively good results of the stacking overall structure experiment is selected as the model of the meta-model layer. In this way, a heterogeneous integrated learning model for electricity theft detection of the stacking structure is constructed. Finally, the experiments of this model are conducted on electricity consumption data from State Grid Corporation of China, and the results show that the detection performance of the proposed method is better than that of the existing state-of-the-art detection method (where the area under receiver operating characteristic curve (AUC) value is 0.98675). Full article
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18 pages, 1246 KiB  
Article
An Adaptive Noise Reduction Approach for Remaining Useful Life Prediction of Lithium-Ion Batteries
by Wenyu Qu, Guici Chen and Tingting Zhang
Energies 2022, 15(19), 7422; https://doi.org/10.3390/en15197422 - 10 Oct 2022
Cited by 9 | Viewed by 1839
Abstract
Lithium-ion batteries are widely used in the electric vehicle industry due to their recyclability and long life. However, a failure of lithium-ion batteries can cause some catastrophic accidents, such as electric car battery explosion fires and so on. To prevent such harm from [...] Read more.
Lithium-ion batteries are widely used in the electric vehicle industry due to their recyclability and long life. However, a failure of lithium-ion batteries can cause some catastrophic accidents, such as electric car battery explosion fires and so on. To prevent such harm from occurring, it is essential to monitor the remaining useful life of lithium-ion batteries and give early warning. In this paper, an adaptive noise reduction approach is proposed to predict the RUL (Remaining Useful Life) of lithium-ion batteries, which uses CEEMDAN (Complete Ensemble Empirical Mode Decomposition with Adaptive Noise) combined with wavelet decomposition to achieve adaptive noise reduction decomposition, and then inputs the obtained IMF (Intrinsic Mode Function) components into LS–RVM (Least Square Relevance Vector Machine) for training, prediction, and reconstruction, so as to achieve high-precision prediction of RUL. Moreover, in order to verify the validity of the model, the model in this paper is compared with other common models. The results demonstrate that the RMSE, MAPE, and MAE of the proposed model are 0.008678, 0.005002, and 0.006894, and that it has higher accuracy than the other common prediction models. Full article
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