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Energies, Volume 15, Issue 6 (March-2 2022) – 348 articles

Cover Story (view full-size image): Renewable sources such as wind gain more and more importance for energy systems all over the world. The intermittent nature requires efficient conversion technologies into media suitable for distri-bution, storage, and later use. Solid oxide electrolysis is such a technology reaching close to 100% efficiency. Remaining challenges to reach large-scale commercial breakthrough are costs and lifetime. Metal supported solid oxide electrolysis cells promise lower costs and high robustness. The image shows a stable performance of metal supported cells with innovative electrode compositions for splitting of steam into hydrogen and oxygen. View this paper
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Article
Soil Organic Matter in Soils of Suburban Landscapes of Yamal Region: Humification Degree and Mineralizing Risks
Energies 2022, 15(6), 2301; https://doi.org/10.3390/en15062301 - 21 Mar 2022
Cited by 1 | Viewed by 607
Abstract
Various research issues related to soil organic matter in permafrost soils are still poorly investigated. At the same time, numerous investigations have shown the importance of permafrost soils, as they serve as a huge reservoir of organic matter. This work is aimed at [...] Read more.
Various research issues related to soil organic matter in permafrost soils are still poorly investigated. At the same time, numerous investigations have shown the importance of permafrost soils, as they serve as a huge reservoir of organic matter. This work is aimed at the investigation of permafrost-affected soils in the southern part of the Yamal region, namely at the assessment of composition (fractional, elemental and molecular) of soil organic matter in topsoils formed under different biogeoclimatogenic conditions in tundra and forest tundra. Special attention was given to assessment of potential vulnerability of soil organic matter in the context of Arctic warming. Results showed the predominance of fulvic acids in the humus of the studied soils, which indicates mineralization risks in the humic substances system of Arctic soils under conditions of further warming. The 13C-NMR analysis of humic acids revealed that all the studied soils are characterized by higher portions of aliphatic groups of carbon and decreased portions of aromatic groups and revealed early stages of the humification process in studied soils. These results contribute to scarcely distributed research of soil organic matter in permafrost soils of the Arctic. Moreover, our research provided new data on the vulnerability of soil organic matter and its possible mineralization risks under pronounced climate change in the Arctic using the modern instrumental technique. Full article
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Article
Does Standardization Improve Carbon Emission Efficiency as Soft Infrastructure? Evidence from China
Energies 2022, 15(6), 2300; https://doi.org/10.3390/en15062300 - 21 Mar 2022
Viewed by 597
Abstract
Standardization in energy-saving and emission-reduction measures has become increasingly important. The impact of standardization on carbon-emission efficiency in China was explored by using panel data from 2002 to 2017. The results showed that standardization significantly improved China’s carbon-emission efficiency, which remained robust after [...] Read more.
Standardization in energy-saving and emission-reduction measures has become increasingly important. The impact of standardization on carbon-emission efficiency in China was explored by using panel data from 2002 to 2017. The results showed that standardization significantly improved China’s carbon-emission efficiency, which remained robust after a series of tests. Furthermore, the development of industry standards had a greater effect on the improvement of carbon-emission efficiency in the economically developed coastal areas, while the development of national standards significantly promoted the improvement of carbon-emission efficiency in the inland areas. An assessment of the impact mechanism demonstrated that standardization affects carbon-emission efficiency through technological progress, industrial modernization, and economies of scale. We compared our findings with the existing literature regarding the governance of a low-carbon economy; we also considered the subsequent policy implications of our findings in terms of sustainable economic development. Full article
Article
Simultaneous Distribution Network Reconfiguration and Optimal Allocation of Renewable-Based Distributed Generators and Shunt Capacitors under Uncertain Conditions
Energies 2022, 15(6), 2299; https://doi.org/10.3390/en15062299 - 21 Mar 2022
Cited by 3 | Viewed by 625
Abstract
Smart grid technology has received ample attention in past years to develop the traditional power distribution network and to enable the integration of distributed generation units (DGs) to satisfy increasing demand loads and to improve network performance. In addition to DGs, integration of [...] Read more.
Smart grid technology has received ample attention in past years to develop the traditional power distribution network and to enable the integration of distributed generation units (DGs) to satisfy increasing demand loads and to improve network performance. In addition to DGs, integration of shunt capacitors (SCs) along with network reconfiguration can also play an important role in improving network performance. Besides, network reconfiguration can help to increase the distributed generation hosting capacity of the network. Some of the research in the literature have presented and discussed the problem of optimal integration of renewable DGs and SCs along with optimal network reconfiguration, while the network load variability and/or the intermittent nature of renewable DGs are neglected. For the work presented in this paper, the SHADE optimization algorithm along with the SOE reconfiguration method have been employed for solving the aforementioned optimization problem with consideration of uncertainty related to both the network load and the output power of the renewable DGs. Maximizing the hosting capacity (HC) of the DGs and reducing network power losses in addition to improving the voltage profile have been considered as optimization objectives. Five different case studies have been conducted considering 33-bus and 59-bus distribution networks. The obtained results validate the effectiveness and the superiority of the employed techniques for maximizing the HC up to 17% and reducing power losses up to 95%. Besides, the results also depict the effect of SC integration and the consideration of uncertainties on achieving the optimization objectives with realistic modeling of the optimization problem. Full article
(This article belongs to the Special Issue Renewable Based Energy Distributed Generation)
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Article
Study on the Characteristics of Water Jet Injection and Temperature Spatial Distribution in the Process of Hot Water Deicing for Insulators
Energies 2022, 15(6), 2298; https://doi.org/10.3390/en15062298 - 21 Mar 2022
Viewed by 489
Abstract
For the benefit of knowing the method of insulator deicing using hot water, this paper investigated the physical aspects of propagation and the spatial temperature distribution of a hot water jet in the air. The numerical calculation model for the water jet flow [...] Read more.
For the benefit of knowing the method of insulator deicing using hot water, this paper investigated the physical aspects of propagation and the spatial temperature distribution of a hot water jet in the air. The numerical calculation model for the water jet flow field was established and validated, and the temperature spatial variation rule and influencing factors of the water jet were analyzed. The results indicate that the water column breaks as the distance increases. The numerical calculation results and the experimental results of the water jet flow field were approximated. As the distance increases, the mass entrainment rate of the water jet gradually increases, and the normalized axis velocity decreases approximately linearly. The jet temperature rises with the rise in the initial temperature of the hot water, and the rising rate decreases with the increase in distance. The temperature of the water jet falls as the jet distance increases. With the rise in the outlet pressure, the temperature of the water jet drops slightly. The influence of environmental wind speed on the water jet temperature is more significant than ambient temperature—the water jet temperature increases as the nozzle diameter increases. The thorough deicing efficiency is most outstanding when the hot water output temperature is around 86 °C and the jet pressure is ~3.5 MPa. Full article
(This article belongs to the Special Issue Testing, Monitoring and Diagnostic of High Voltage Equipment)
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Article
Prediction Model for the Viscosity of Heavy Oil Diluted with Light Oil Using Machine Learning Techniques
Energies 2022, 15(6), 2297; https://doi.org/10.3390/en15062297 - 21 Mar 2022
Cited by 2 | Viewed by 588
Abstract
Due to the presence of asphaltene, the flow assurance of high viscosity crude oil becomes more challenging and costly to produce in wellbores and pipelines. One of the most effective ways to reduce viscosity is to blend heavy oil with light oil. However, [...] Read more.
Due to the presence of asphaltene, the flow assurance of high viscosity crude oil becomes more challenging and costly to produce in wellbores and pipelines. One of the most effective ways to reduce viscosity is to blend heavy oil with light oil. However, the viscosity measurement of diluted heavy crude is either time-consuming or inaccurate. This work aims to develop a more accurate viscosity model of diluted heavy crude based on machine learning techniques. A multilayer neural network is used to predict the viscosity of heavy oil diluted with lighter oil. The input data used in the training include temperature, light oil viscosity, heavy oil viscosity, and dilution ratio. In this modeling process, 156 datasets were retrieved from the available iterature of various heavy-oil fields in China. Part of the data (80%) is used to train the developed models using Adam optimizer algorithms, while the other part of the data (20%) is used to predict the viscosity of heavy oil diluted with lighter. The performance and accuracy of the machine learning models were tested and compared with the existing viscosity models. It was found that the new model can predict the viscosity of diluted heavy oil with higher accuracy, and it performs better than other models. The absolute average relative error is 10.44%, the standard deviation of the relative error is 8.45%, and the coefficient of determination is R2 = 0.95. The viscosity predicted by the neural network outperformed existing correlations by the statistical analysis used for the datasets available in the literature. Therefore, the method proposed in this paper can better estimate the viscosity of diluted heavy crude oil and has important promotion value. Full article
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Article
How to Meet the Green Deal Objectives—Is It Possible to Obtain 100% RES at the Regional Level in the EU?
Energies 2022, 15(6), 2296; https://doi.org/10.3390/en15062296 - 21 Mar 2022
Cited by 4 | Viewed by 664
Abstract
The subject matter discussed in the article concerns the problem of the energy transformation of the European Union (EU) countries. In the case of the EU, the energy transformation has specific characteristics due to formal legal and institutional provisions. This means that the [...] Read more.
The subject matter discussed in the article concerns the problem of the energy transformation of the European Union (EU) countries. In the case of the EU, the energy transformation has specific characteristics due to formal legal and institutional provisions. This means that the member states are obliged to implement the adopted Community Energy Strategy, which was defined under the European Green Deal. According to the EU policy, all member states are to have climate-neutral and zero-gas-emission economies by 2050. The energy transformation is to be largely based on the diversification of the energy sources used, with a dominance of renewable energy sources (RES). The article presents a research problem, where the question was asked whether achieving climate-neutral energy independence based solely on RES is possible at the regional level. It seems that the positive answer is an important argument in the discussion about the possibility of all member states achieving the goals set under the European Green Deal. Additionally, stating the possibility of energy independence from RES for a selected region is an important argument to promote just and bottom-up initiatives in order to carry out the energy transformation more effectively. The assessment of the energy potential from renewable sources at the regional level was carried out on the example of a selected NUTS 2 region, the Greater Poland Voivodeship in Poland. The main objective of the study is to analyze the possibility of obtaining independence from RES by the selected Greater Poland Voivodeship. The implementation of the objective consists of determining the energy potential from RES in the Voivodeship under study on the basis of the methods of a geographic information system (GIS). GIS methods were selected due to the fact that they allow for the spatial positioning of point, line, and surface structures in relation to the potential of RES, thus ensuring high accuracy of the obtained estimates. The analysis carried out in the study shows that the technical potential of RES in the Greater Poland Voivodeship is higher than the current electricity and heat usage. This means that by focusing solely on RES in the region, the Greater Poland Voivodeship can fully meet the energy demand thanks to its green resources. It should be emphasized that the Greater Poland Voivodeship is one of the coal-dependent regions in Poland that has already prepared a structured plan of just transformation. A locally and bottom-up prepared strategy assumes the conversion of the region from a “Coal Energy Region” into a “Green Energy Valley” in which economic development will be strictly connected to RES energy independence. Full article
(This article belongs to the Special Issue Renewable and Sustainable Energy: Current State and Prospects)
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Article
Dual-Active-Bridge Model and Control for Supporting Fast Synthetic Inertial Action
Energies 2022, 15(6), 2295; https://doi.org/10.3390/en15062295 - 21 Mar 2022
Viewed by 796
Abstract
This article proposes a dual-active-bridge control to support the fast synthetic inertial action in DC microgrids. First of all, the selection of the isolated DC/DC converter to link an energy storage system with the DC bus in a microgrid is analyzed and the [...] Read more.
This article proposes a dual-active-bridge control to support the fast synthetic inertial action in DC microgrids. First of all, the selection of the isolated DC/DC converter to link an energy storage system with the DC bus in a microgrid is analyzed and the advantages of the dual-active-bridge converter controlled by a single-phase shift modulation justify its selection. An active front-end can be then adapted to connect the DC bus with an AC grid. Secondly, this paper presents the design of a discrete PI controller for supporting fast synthetic inertial action. In particular, a discrete dual-active-bridge model based on the transferred power between both converter bridges, which overcomes the approximations of the output current linearization model, is proposed. Moreover, the article introduces a novel equation set to directly and dynamically tune discrete PI parameters to fulfill the design frequency specifications based on the inversion formulae method. In this way, during the voltage/power transients on the DC bus, the controller actively responds and recovers those transients within a grid fundamental cycle. Since the developed set of control equations is very simple, it can be easily implemented by a discrete control algorithm, avoiding the use of offline trial and error procedures which may lead to system instability under large load variations. Finally, the proposed control system is evaluated and validated in PLECS simulations and hardware-in-the-loop tests. Full article
(This article belongs to the Special Issue Control and Stability of Grid-Connected Power Electronic Converters)
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Article
Research on Fuel Cell Fault Diagnosis Based on Genetic Algorithm Optimization of Support Vector Machine
Energies 2022, 15(6), 2294; https://doi.org/10.3390/en15062294 - 21 Mar 2022
Viewed by 616
Abstract
The fuel cell engine mechanism model is used to research fault diagnosis based on a data-driven method to identify the failure of proton exchange membrane fuel cells in the process of operation, which leads to the degradation of system performance and other problems. [...] Read more.
The fuel cell engine mechanism model is used to research fault diagnosis based on a data-driven method to identify the failure of proton exchange membrane fuel cells in the process of operation, which leads to the degradation of system performance and other problems. In this paper, an extreme learning machine and a support vector machine are applied to classify the usual faults of fuel cells, including air compressor faults, air supply pipe and return pipe leaks, stack flooding faults and temperature controller faults. The accuracy of fault classification was 78.67% and 83.33% respectively. In order to improve the efficiency of fault classification, a genetic algorithm is used to optimize the parameters of the support vector machine. The simulation results show that the accuracy of fault classification was improved to 94% after optimization. Full article
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Article
Evaluation Methodology of Rotary Flow Dividers Used as Pressure Intensifiers with Creation of a New Pressure Multiplying Efficiency
Energies 2022, 15(6), 2293; https://doi.org/10.3390/en15062293 - 21 Mar 2022
Viewed by 492
Abstract
For most of the technical community, rotary flow dividers are known for synchronization of two or more hydraulic actuators. However, there is also a possibility to use them for pressure multiplication, flow regeneration, or speed control. For those applications, there is a need [...] Read more.
For most of the technical community, rotary flow dividers are known for synchronization of two or more hydraulic actuators. However, there is also a possibility to use them for pressure multiplication, flow regeneration, or speed control. For those applications, there is a need to describe the behavior of its quantities. This article reveals a new evaluation methodology for rotary flow dividers when they are unconventionally used as pressure multipliers and also reveals a new quantity-pressure multiplying efficiency. Then, there is an experiment provided between two rotary flow dividers with different designs, where there is a new evaluation methodology used. On the base of that, it is possible to compare and decide which divider is more likely to be used in multiplying circuits and more suitable for further investigation from the perspective of new designs. With this evaluation methodology, it is possible to compare much more than two different dividers. It is possible to run more tests and experiments with arbitrary dividers, and their new design changes to reach as efficient a pressure multiplication or flow regeneration as possible. Full article
(This article belongs to the Special Issue Gear Pumps and Motors)
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Article
Effects of Oxygen-Enhanced Combustion Methods on Combustion Characteristics of Non-Premixed Swirling Flames
Energies 2022, 15(6), 2292; https://doi.org/10.3390/en15062292 - 21 Mar 2022
Cited by 2 | Viewed by 518
Abstract
The objective of the present study was to experimentally investigate and compare the characteristics of three oxygen-enhanced combustion (OEC) methods; premix enrichment (PE), air-oxy/fuel combustion (AO), and additionally also oxygen lancing (OL) method. The overall oxygen concentration varied from 21% to 38%. Combustion [...] Read more.
The objective of the present study was to experimentally investigate and compare the characteristics of three oxygen-enhanced combustion (OEC) methods; premix enrichment (PE), air-oxy/fuel combustion (AO), and additionally also oxygen lancing (OL) method. The overall oxygen concentration varied from 21% to 38%. Combustion tests were carried out using the gas burner with the thermal input of 750 kW fired by natural gas. The characteristics of OEC methods, such as the concentration of nitrogen oxides and carbon monoxide in flue gas, in-flame temperatures distribution in the horizontal symmetry plane of the combustion chamber, heat flux to the combustion chamber wall, flue gas temperature, and the stability of flame were investigated. NOx emissions increased by more than 40 times and by 20 times for the PE method. The tests using the AO and OL methods with NOx emissions below 150 mg/Nm3 at all oxygen concentrations showed significantly better results. For all OEC methods, radiative heat transfer increased with increasing oxygen concentration. The available heat was 20% higher at 38% O2 than at 21% O2. The flue gas temperature decreased with increasing oxygen concentration, which was affected by a decrease in N2 concentration in the oxidizer and a simultaneous increase in radiant heat flux. Full article
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Review
Wind Energy Scenario, Success and Initiatives towards Renewable Energy in India—A Review
Energies 2022, 15(6), 2291; https://doi.org/10.3390/en15062291 - 21 Mar 2022
Cited by 3 | Viewed by 1079
Abstract
Power generation using wind has been extensively utilised, with substantial capacity add-on worldwide, during recent decades. The wind power energy sector is growing, and has turned into a great source of renewable power production. In the past decades of the 21st century, the [...] Read more.
Power generation using wind has been extensively utilised, with substantial capacity add-on worldwide, during recent decades. The wind power energy sector is growing, and has turned into a great source of renewable power production. In the past decades of the 21st century, the capacity of installed wind energy has almost doubled every three years. This review paper presents the crucial facets and advancement strategies that were approved and adopted by the Government of India for intensifying the country’s own power safety, by the appropriate use of existing power sources. From India’s viewpoint, wind energy is not only utilized for power production but also to provide power in a more economical way. The particulars of India’s total energy production, contributions of numerous renewable sources and their demand are also encompassed in this paper. After an exhaustive review of the literature, detailed facts have been identified about the present position of wind energy, with an emphasis on government achievements, targets, initiatives, and various strategic advances in the wind power sector. Wind power potential is discussed, which can assist renewable power companies to select efficient and productive locations. All analyses carried out in this paper will be incredibly valuable to future renewable energy investors and researchers. The current scenario of wind power production in India is also paralleled with that of other globally prominent countries. Full article
(This article belongs to the Special Issue Advances in Maintenance Management)
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Article
A Novel Denoising Auto-Encoder-Based Approach for Non-Intrusive Residential Load Monitoring
Energies 2022, 15(6), 2290; https://doi.org/10.3390/en15062290 - 21 Mar 2022
Cited by 1 | Viewed by 516
Abstract
Mounting concerns pertaining to energy efficiency have led to the research of load monitoring. By Non-Intrusive Load Monitoring (NILM), detailed information regarding the electric energy consumed by each appliance per day or per hour can be formed. The accuracy of the previous residential [...] Read more.
Mounting concerns pertaining to energy efficiency have led to the research of load monitoring. By Non-Intrusive Load Monitoring (NILM), detailed information regarding the electric energy consumed by each appliance per day or per hour can be formed. The accuracy of the previous residential load monitoring approach relies heavily on the data acquisition frequency of the energy meters. It brings high overall cost issues, and furthermore, the differentiating algorithm becomes much more complicated. Based on this, we proposed a novel non-Intrusive residential load disaggregation method that only depends on the regular data acquisition speed of active power measurements. Additionally, this approach brings some novelties to the traditionally used denoising Auto-Encoder (dAE), i.e., the reconfiguration of the overlapping parts of the sliding windows. The median filter is used for the data processing of the overlapping window. Two datasets, i.e., the Reference Energy Disaggregation Dataset (REDD) and TraceBase, are used for test and validation. By numerical testing of the real residential data, it proves that the proposed method is superior to the traditional Factorial Hidden Markov Model (FHMM)-based approach. Furthermore, the proposed method can be used for energy data, disaggregation disregarding the brand and model of each appliance. Full article
(This article belongs to the Special Issue Situation Awareness for Smart Distribution Systems)
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Article
LPSRS: Low-Power Multi-Hop Synchronization Based on Reference Node Scheduling for Internet of Things
Energies 2022, 15(6), 2289; https://doi.org/10.3390/en15062289 - 21 Mar 2022
Viewed by 569
Abstract
Time synchronization is one of the most fundamental problems on the internet of things (IoT). The IoT requires low power and an efficient synchronization protocol to minimize power consumption and conserve battery power. This paper introduces an efficient method for time synchronization in [...] Read more.
Time synchronization is one of the most fundamental problems on the internet of things (IoT). The IoT requires low power and an efficient synchronization protocol to minimize power consumption and conserve battery power. This paper introduces an efficient method for time synchronization in the IoT called low-power multi-hop synchronization (LPSRS). It employs a reference node scheduling mechanism to avoid packet collisions and minimize the communication overhead, which has a big impact on power consumption. The performance of LPSRS has been evaluated and compared to previous synchronization methods, HRTS and R-Sync, via real hardware networks and simulations. The results show that LPSRS achieves a better performance in terms of power consumption (transmitted messages). In particular, for a large network of 450 nodes, LPSRS reduced the total number of transmitted messages by 53% and 49% compared to HRTS and R-Sync, respectively. Full article
(This article belongs to the Topic IoT for Energy Management Systems and Smart Cities)
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Article
State Estimation Fusion for Linear Microgrids over an Unreliable Network
Energies 2022, 15(6), 2288; https://doi.org/10.3390/en15062288 - 21 Mar 2022
Viewed by 684
Abstract
Microgrids should be continuously monitored in order to maintain suitable voltages over time. Microgrids are mainly monitored remotely, and their measurement data transmitted through lossy communication networks are vulnerable to cyberattacks and packet loss. The current study leverages the idea of data fusion [...] Read more.
Microgrids should be continuously monitored in order to maintain suitable voltages over time. Microgrids are mainly monitored remotely, and their measurement data transmitted through lossy communication networks are vulnerable to cyberattacks and packet loss. The current study leverages the idea of data fusion to address this problem. Hence, this paper investigates the effects of estimation fusion using various machine-learning (ML) regression methods as data fusion methods by aggregating the distributed Kalman filter (KF)-based state estimates of a linear smart microgrid in order to achieve more accurate and reliable state estimates. This unreliability in measurements is because they are received through a lossy communication network that incorporates packet loss and cyberattacks. In addition to ML regression methods, multi-layer perceptron (MLP) and dependent ordered weighted averaging (DOWA) operators are also employed for further comparisons. The results of simulation on the IEEE 4-bus model validate the effectiveness of the employed ML regression methods through the RMSE, MAE and R-squared indices under the condition of missing and manipulated measurements. In general, the results obtained by the Random Forest regression method were more accurate than those of other methods. Full article
(This article belongs to the Special Issue Fault Locations for Smart Grids)
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Article
A New Method for Capturing CO2 from Effluent Gases Using a Rice-Based Product
Energies 2022, 15(6), 2287; https://doi.org/10.3390/en15062287 - 21 Mar 2022
Viewed by 559
Abstract
In 2013, UAE imported around 772 million kilograms of rice, making it one of the largest consumers of this popular grain in the world. However, 40% of rice available in the market is discarded, contributing to the country’s CO2 footprint. Given that [...] Read more.
In 2013, UAE imported around 772 million kilograms of rice, making it one of the largest consumers of this popular grain in the world. However, 40% of rice available in the market is discarded, contributing to the country’s CO2 footprint. Given that CO2 emissions are recognized as a significant contributor to climate change and efforts aimed at their reduction are proving insufficient for combatting the global increase in temperature, various approaches aimed at its removal from the atmosphere have been proposed. The goal of this study is to contribute to this initiative by proposing a new method for CO2 removal based on a special gas contact device filled with buffered puffed rice cakes obtained by heating in a purposely designed sealed chamber at high pressure to obtain layers with 9−12 mm thickness. The resulting cakes are subsequently immersed in a sodium hydroxide liquor (0.25−2.5 M) to increase the moisture content to 5% and pH to >11.0. In the experiments, different rice structures (stacked layers, rice grains, and multi-spaced layers) were tested, varying the CO2 percentage in the simulated effluent gas (1−15%). The highest CO2 uptake value (7.52 × 10−3 mole CO2/cm2 rice cake surface area) was achieved using 10% CO2 and a 500 mL/min flow rate with rice cakes of 80 mm diameter, comprising 12 mm thick layers that occupied 20% of the device volume. These results indicate that the proposed design exhibits high CO2 removal efficiency and should be further optimized in future investigations. Full article
(This article belongs to the Topic Advances in Clean Energies)
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Article
Energy Costs Impact on Disabled Children’s Rehabilitation Opportunities in Kazakhstan
Energies 2022, 15(6), 2286; https://doi.org/10.3390/en15062286 - 21 Mar 2022
Viewed by 517
Abstract
This article examines the costs for families raising disabled children, who, in world social policy, belong to socially vulnerable groups of the population. The purpose of this article is to assess the impact of energy consumption on the ability of a family to [...] Read more.
This article examines the costs for families raising disabled children, who, in world social policy, belong to socially vulnerable groups of the population. The purpose of this article is to assess the impact of energy consumption on the ability of a family to provide rehabilitation for a disabled child in the present and the possibility of his independent life in the future. A sociological survey was administered to respondents in five regions of Kazakhstan, with subsequent processing of the results obtained by statistical methods. The survey was based on a methodological approach in accordance with the identification of four types of restrictions: direct childcare costs; indirect family costs, i.e., losses (household energy consumption aspect); assessment of the opportunity to work; and assessment of the parents’ ability to stay healthy. The PLS–PM model-based structural modeling was carried out. In the model, four types of constraints as dependent variables were accepted. In the course of the model application, three hypotheses regarding energy costs were confirmed. The significance of energy costs in the system of restrictions for families with disabled children was determined. In conclusion, the qualitative characteristics of the relationships allowed identification of the problems in the current support system for families with disabled children in Kazakhstan, which is focused on the partial compensation of direct costs. Energy consumption was determined to be sufficiently important. This results in the misuse of benefits for the rehabilitation of a child because parents, especially from incomplete and low-income families, are forced to choose between paying utility bills and rehabilitating a child. Energy costs also limit the family’s ability to meet the direct costs of the child and long-term savings related to the child’s future. We propose the subsidization of energy utilities for families with disabled children, partially replacing targeted social assistance with vouchers for the purchase of household electrical appliances and rehabilitation equipment with energy-saving characteristics. In further studies, issues regarding the use of tax deductions and tax credits as an alternative support measure, which is currently not used in Kazakhstan, will be investigated. Full article
(This article belongs to the Special Issue Economy, Social Policy and Forecast Analysis in Energy Industry)
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Article
Investigation of Heat Transfer and Pressure Drop for R744 in a Horizontal Smooth Tube of R744/R404A Hybrid Cascade Refrigeration System—Part 1: Intermediate Temperature Region
Energies 2022, 15(6), 2285; https://doi.org/10.3390/en15062285 - 21 Mar 2022
Viewed by 524
Abstract
In this study, the evaporation heat transfer characteristics of an intermediate temperature of R744 in a smooth horizontal tube, when operating as an indirect refrigeration system (IRS) among hybrid cascade refrigeration systems (HCRSs), are evaluated. Studies on the characteristics of intermediate-temperature evaporation heat [...] Read more.
In this study, the evaporation heat transfer characteristics of an intermediate temperature of R744 in a smooth horizontal tube, when operating as an indirect refrigeration system (IRS) among hybrid cascade refrigeration systems (HCRSs), are evaluated. Studies on the characteristics of intermediate-temperature evaporation heat transfer under the operating conditions of evaporators used in actual refrigeration systems, such as IRS, cascade refrigeration systems, and HCRS, used in supermarkets are lacking. Thus, this study provides basic data on the characteristics of evaporation heat transfer of R744 in the evaporators of refrigerators used in supermarkets. The tube employed to the evaporation experiment in this study was a horizontal smooth copper tube with a length of 8000 mm and an inner diameter of 11.46 mm. The experimental variables were measured over a wide range of mass flux of 200–500 kg/(m2·s), heat flux of 10–40 kW/m2, and saturation temperature of −40–0 °C. The main results are summarized as follows: (1) The application of Kandlikar’s correlation formula at an evaporation temperature of −20 °C in an IRS helps in a good prediction of the R744 evaporation heat transfer coefficient. (2) The pressure drop according to the heat and mass flux showed the same heat transfer coefficient trend, but the pressure drop at saturation temperature was different from the trend of heat transfer coefficient. Full article
(This article belongs to the Special Issue Heat Transfer Characteristics and Two-Phase Flow Performance)
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Article
An Electrothermal Model to Predict Thermal Characteristics of Lithium-Ion Battery under Overcharge Condition
Energies 2022, 15(6), 2284; https://doi.org/10.3390/en15062284 - 21 Mar 2022
Viewed by 699
Abstract
Understanding the thermal characteristics of lithium-ion batteries (LIBs) under various operating situations is critical for improving battery safety. Although the application of LIBs in the real world is mostly transient, many previous models consider the phenomenon of the constant state. This study examines [...] Read more.
Understanding the thermal characteristics of lithium-ion batteries (LIBs) under various operating situations is critical for improving battery safety. Although the application of LIBs in the real world is mostly transient, many previous models consider the phenomenon of the constant state. This study examines thermal behavior by developing a 2D electrothermal model to predict the thermal behavior of LIBs with overcharge abuse in high thermal conditions. The 18,650 cylindrical LiCoO2 graphite is investigated in a thermally controlled chamber at 35, 50, and 60 °C with a K-type thermocouple mounted on the LIB surface under charging rates of 1C, 2C, and 3C to acquire quantitative data regarding the thermal response of LIBs. Maximum critical temperatures are found at 62.6 to 78.9 °C, 66.4 to 83.5 °C, and 72.1 to 86.6 °C at 1C, 2C, and 3C, respectively. Comparing simulation analysis and experimental conditions, the highest relative error of 1.71% was obtained. It was found that relative errors increase as the charging rate increases. Moreover, increasing the charging current and surrounding temperature significantly increases the battery’s surface temperature. Furthermore, battery heat distribution appears almost uniform and tends to increase towards the positive terminal because cathode material is highly resistant. In addition, increasing the LIB heat transfer coefficient could positively improve the battery performance by eventually curbing the rise in battery temperature and reducing non-uniformity. Full article
(This article belongs to the Topic Safety of Lithium-ion Batteries)
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Review
Review on Material and Design of Anode for Microbial Fuel Cell
Energies 2022, 15(6), 2283; https://doi.org/10.3390/en15062283 - 21 Mar 2022
Viewed by 820
Abstract
Microbial Fuel Cell (MFC) is a bio-electrochemical system that generates electricity by anaerobic oxidation of substrates. An anode is the most critical component because the primary conversion of wastewater into electrons and protons takes place on the surface of the anode, where a [...] Read more.
Microbial Fuel Cell (MFC) is a bio-electrochemical system that generates electricity by anaerobic oxidation of substrates. An anode is the most critical component because the primary conversion of wastewater into electrons and protons takes place on the surface of the anode, where a biofilm is formed. This paper describes the essential properties of the anode and classifies its types according to the material used to make it. Anode material is responsible for the flow of electrons generated by the microorganism; hence biocompatibility and conductivity can considered to be the two most important properties. In this paper, the various modification strategies to improve the performance of anodes of MFC are explained through the review of researchers’ published work in this field. The shape and size of the anode turned out to be very significant as the microbial growth depends on the available surface area. The attachment of biofilm on the surface of an anode largely depends on the interfacial surface chemistry. Methods for improving MFC performance by altering the anode material, architecture, biocompatibility, and longevity are discussed with a future perspective giving special importance to the cost. Full article
(This article belongs to the Special Issue New Frontiers in Microbial Fuel Cells)
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Article
Prediction Method for Surface Subsidence of Coal Seam Mining in Loess Donga Based on the Probability Integration Model
Energies 2022, 15(6), 2282; https://doi.org/10.3390/en15062282 - 21 Mar 2022
Cited by 2 | Viewed by 473
Abstract
The accurate prediction of surface subsidence is a significant foundation for the damage assessment of coal seam mining and ecological environment reclamation in loess donga. However, conventional models are very problematic, and the reliability of prediction is usually low. Therefore, we propose a [...] Read more.
The accurate prediction of surface subsidence is a significant foundation for the damage assessment of coal seam mining and ecological environment reclamation in loess donga. However, conventional models are very problematic, and the reliability of prediction is usually low. Therefore, we propose a method for predicting surface subsidence of coal seam mining in loess donga that is based on the probability integration model, combined with the movement principle of rock and soil layers in the respective study area, and considering the influence of slope stability and additional mining slip on mining subsidence. The feasibility of our new method was verified by a case study in the N1114 working face of the Ningtiaota coal mine (China) that is situated in an area with abundant loess dongas. The results show that slope slippage is the source of error in the prediction of subsidence in loess donga. The prediction idea of “dividing the surface of loess donga into horizontal strata area and slope sub-area, and predicting the subsidence value of the two areas, respectively” is put forward. A method for predicting the subsidence value of two regions is established. First, based on the theory of probability integral and rock formation movement, the probability integral parameters of the horizontal stratum area are determined, and the subsidence basins in the area are superimposed and calculated. Secondly, according to the slope stability and slip principle, the additional displacement of subsidence in the slope area with mining instability coefficient Gcs > 0.87 is calculated. Finally, combined with the subsidence prediction results of the strata area and the slope sub-area, and the position of the slope, the accurate prediction of the surface subsidence in loess donga is realized. Our results show that the agreement between the curves predicted from our calculations and from the measured data are between 88.7–97.8%. The calculated error of the additional displacement of slope mining slip is between 1.0–9.8%. The excellent correlation between the modelled and measured data documents that our method provides, demonstrated a new efficient and valuable tool for the precise prediction of damages induced by mining of underground coal seams in loess donga. Full article
(This article belongs to the Topic Mining Safety and Sustainability)
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Article
Understanding Off-Gassing of Biofuel Wood Pellets Using Pellets Produced from Pure Microcrystalline Cellulose with Different Additive Oils
Energies 2022, 15(6), 2281; https://doi.org/10.3390/en15062281 - 21 Mar 2022
Viewed by 417
Abstract
Fuel wood pellets have the tendency of undergoing self-heating and off-gassing during storage and transportation. Self-heating can lead to spontaneous combustion and cause fires while toxic gasses such as carbon monoxide and some volatile organic compounds released due to off-gassing are a human [...] Read more.
Fuel wood pellets have the tendency of undergoing self-heating and off-gassing during storage and transportation. Self-heating can lead to spontaneous combustion and cause fires while toxic gasses such as carbon monoxide and some volatile organic compounds released due to off-gassing are a human health and environmental hazard. Previous research suggests that the self-heating and off-gassing of wood pellets are as a result of the oxidation of wood extractives. The aim of this study was to identify the extractives, i.e., fatty and resin acids that are responsible for the emissions of carbon monoxide, carbon dioxide and methane from wood pellets by testing the off-gassing tendencies of pellets produced from synthetic microcrystalline cellulose and different additive oils. The additive oils were intentionally selected to represent different types of wood extractives (mainly fatty and resin acids) and they included: tall oil, pine rosin, linseed oil and coconut oil. The highest mean concentrations of carbon monoxide, carbon dioxide and methane were recorded from cellulose pellets with added linseed oil. The concentrations of carbon monoxide and methane for the other four pellet types were negligible and there was no carbon dioxide emission. Pellets with added linseed oil had high off-gas emissions due to the high content of unsaturated fatty acids compared to other pellet types. Full article
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Article
Study on Geometric Characteristics and Quantitative Description Method of Casing Deformation during Shale Reservoir Hydraulic Fracturing
Energies 2022, 15(6), 2280; https://doi.org/10.3390/en15062280 - 21 Mar 2022
Viewed by 365
Abstract
Casing deformation is a common but serious problem experienced during hydraulic fracturing operations in shale reservoirs. The Multi-Finger Imaging Tool is used to measure the casing deformation where the casing inner diameter is the only parameter used to characterize the deformation. Many deformed [...] Read more.
Casing deformation is a common but serious problem experienced during hydraulic fracturing operations in shale reservoirs. The Multi-Finger Imaging Tool is used to measure the casing deformation where the casing inner diameter is the only parameter used to characterize the deformation. Many deformed casing geometric details are often ignored, and these geometric characteristics are helpful for revealing the casing deformation mechanism. In this study, we established a quantitative method to describe the casing deformation using methods of judging the similarity of curves. By comparing the field casing deformation sections and the initial casing section, we categorized the casing deformation sections into concave and elliptical types. Furthermore, using the centroid calculation, elliptical type was sub-divided into symmetric ellipse type and eccentric ellipse type. On the basis of the Weiyuan and Guandong oil field’s fault distribution maps, we demonstrated that the fault slip could be the main cause of concave type and eccentric ellipse type. A numerical study was then carried out to ascertain whether fault slip can cause concave type and eccentric ellipse type casing deformations and to establish the relationship between fault slip magnitude and casing deformation. The results support the idea that concave type and eccentric ellipse type casing deformation are caused by the fault slip. Sensitivity analysis showed that the shape of the casing section was largely influenced by the dip angle, while the change of the casing inner diameter was largely influenced by the strike angle. The method proposed herein presents a useful step towards the prediction of the causes of casing deformation and provides a relationship between casing inner diameter change and fault slip. Full article
(This article belongs to the Special Issue Research and Development Progress in Oil Shale)
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Article
Qualitative Analysis of Household Energy Awareness in Poland
Energies 2022, 15(6), 2279; https://doi.org/10.3390/en15062279 - 21 Mar 2022
Cited by 5 | Viewed by 496
Abstract
Because of disruptive changes in energy businesses and services, as well as changes in people’s lifestyles around the world, energy demand and consumption have risen quickly in recent decades. A household energy awareness literature review was conducted. The survey was conducted in Poland [...] Read more.
Because of disruptive changes in energy businesses and services, as well as changes in people’s lifestyles around the world, energy demand and consumption have risen quickly in recent decades. A household energy awareness literature review was conducted. The survey was conducted in Poland with over 1097 respondents. Additionally, it was given a qualitative analysis. At the same time, in order to consider why energy consumption in households is increasing, a traditional quality management tool was used—the Ishikawa diagram. The Pareto–Lorenz diagram was used to analyze the causes of the increase in energy consumption in households. A model of the causes of increasing energy consumption in households has been built. The researchers calculated the chi-square test, which allows them to determine Pearson’s C coefficient. The C-Pearson coefficient can be calculated using the Chi square value. The results of the study clearly show that the respondents have knowledge of energy and the factors that influence the increase in its consumption but are not aware of why energy should be saved and what it means for the environment. The authors propose ways to build the awareness of household users through a modern quality management tool called the interrelationship diagram. Full article
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Review
A Review on Peak Load Shaving in Microgrid—Potential Benefits, Challenges, and Future Trend
Energies 2022, 15(6), 2278; https://doi.org/10.3390/en15062278 - 21 Mar 2022
Viewed by 557
Abstract
This study aims to review the potential benefits of peak load shaving in a microgrid system. The relevance of peak shaving for a microgrid system is presented in this research review at the outset to justify the peak load shaving efficacy. The prospective [...] Read more.
This study aims to review the potential benefits of peak load shaving in a microgrid system. The relevance of peak shaving for a microgrid system is presented in this research review at the outset to justify the peak load shaving efficacy. The prospective benefits of peak shaving in microgrid systems, including technological, economic, and environmental advantages, are thoroughly examined. This review study also presents a cost–benefit numerical analysis to illustrate the economic viability of peak load shaving for a microgrid system. Different peak shaving approaches are briefly discussed, as well as the obstacles of putting them into practice. Finally, this review study reveals some potential future trends and possible directions for peak shaving research in microgrid systems. This review paper lays a strong foundation for identifying the potential benefits of peak shaving in microgrid systems and establishing suitable projects for practical effectuation. Full article
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Article
Online Estimation of the Mechanical Parameters of a Wind Turbine with Doubly Fed Induction Generator by Utilizing Turbulence Excitations
Energies 2022, 15(6), 2277; https://doi.org/10.3390/en15062277 - 21 Mar 2022
Viewed by 361
Abstract
In this paper, a new method using wind turbulence excitation is proposed to estimate the parameters of the mechanical system (drivetrain and pitch angle controller) in a Doubly Fed Induction Generator (DFIG) Wind Turbine (WT). Firstly, simulations were carried out for a DFIG [...] Read more.
In this paper, a new method using wind turbulence excitation is proposed to estimate the parameters of the mechanical system (drivetrain and pitch angle controller) in a Doubly Fed Induction Generator (DFIG) Wind Turbine (WT). Firstly, simulations were carried out for a DFIG WT under turbulence excitations. The spectral contents of the responses imply that the transients of the electrical system (generator and converter), which are much faster than those of the mechanical system, can be neglected when estimating the mechanical parameters. Based on this, a simplified model related to the mechanical system of the DFIG WT was derived by applying the model reduction technique. Secondly, the parameter sensitivity of Power Spectral Density (PSD) was used to quantify the impacts of individual parameters on the dynamics of the mechanical system, and the influential parameters were selected on the basis of the sensitivity results. Finally, a weighted least-squares optimization problem, which is suitable for a system with close oscillation modes, was formulated for parameter estimation. The estimation results based on two different types of optimization methods were compared, and their estimation accuracies validate the effectiveness of the proposed method. Full article
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Article
Single-Phase Charging of EV Embedded Batteries in an MMC with Submodule Override Capability
Energies 2022, 15(6), 2276; https://doi.org/10.3390/en15062276 - 21 Mar 2022
Viewed by 545
Abstract
The modular multilevel converter with embedded batteries is a viable alternative in electric vehicle drive systems. This research investigates integrated charging of the embedded batteries in a three-phase converter from a single-phase source without any additional hardware requirements. Two phases of the converter [...] Read more.
The modular multilevel converter with embedded batteries is a viable alternative in electric vehicle drive systems. This research investigates integrated charging of the embedded batteries in a three-phase converter from a single-phase source without any additional hardware requirements. Two phases of the converter are connected to the supply while the third converter leg is not connected. In a typical charging of the converter batteries, the batteries with a lower state of charge are prioritised. Then all batteries are balanced at an average global state of charge. This research proposes a new sorting algorithm of the converter batteries with an override capability to bypass any individual submodule if required. This bypassing capability is modulation method independent, thus can be integrated with any modulation method. Simulation results and a real-time emulation of the charging system validate the proposed control method and the override algorithm. In addition, an open-loop switching technique is integrated with a new nearest level control-based measurement method of the battery terminal voltage to estimate its initial state of charge. This measurement facilitates a reduced number of voltage sensors for hardware implementation. This method was simulated and validated by comparing the calculated and the measured values of the battery initial state of charge. Real-time emulation of the system utilising hardware-in-the-loop apparatus was carried out, which confirmed the developed control system functions as expected. Full article
(This article belongs to the Section F: Electrical Engineering)
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Review
Expansion Planning of Power Distribution Systems Considering Reliability: A Comprehensive Review
Energies 2022, 15(6), 2275; https://doi.org/10.3390/en15062275 - 21 Mar 2022
Cited by 1 | Viewed by 704
Abstract
One of the big concerns when planning the expansion of power distribution systems (PDS) is reliability. This is defined as the ability to continuously meet the load demand of consumers in terms of quantity and quality. In a scenario in which consumers increasingly [...] Read more.
One of the big concerns when planning the expansion of power distribution systems (PDS) is reliability. This is defined as the ability to continuously meet the load demand of consumers in terms of quantity and quality. In a scenario in which consumers increasingly demand high supply quality, including few interruptions and continuity, it becomes essential to consider reliability indices in models used to plan PDS. The inclusion of reliability in optimization models is a challenge, given the need to estimate failure rates for the network and devices. Such failure rates depend on the specific characteristics of a feeder. In this context, this paper discusses the main reliability indices, followed by a comprehensive survey of the methods and models used to solve the optimal expansion planning of PDS considering reliability criteria. Emphasis is also placed on comparing the main features and contributions of each article, aiming to provide a handy resource for researchers. The comparison includes the decision variables and reliability indices considered in each reviewed article, which can be used as a guide to applying the most suitable method according to the requisites of the system. In addition, each paper is classified according to the optimization method, objective type (single or multiobjective), and the number of stages. Finally, we discuss future research trends concerning the inclusion of reliability in PDS expansion planning. Full article
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Article
Investigation of the Degradation Behavior of Cyclophosphamide by Catalytic Ozonation Based on Mg(OH)2
Energies 2022, 15(6), 2274; https://doi.org/10.3390/en15062274 - 21 Mar 2022
Viewed by 404
Abstract
Metal hydroxides, owing to their catalytic active sites for the decomposition of O3 to Reactive Oxygen Species (ROS), have been adapted for catalytic ozonation of micropollutants in wastewater. In this study, commercial Mg (OH)2 was used for the degradation of cyclophosphamide [...] Read more.
Metal hydroxides, owing to their catalytic active sites for the decomposition of O3 to Reactive Oxygen Species (ROS), have been adapted for catalytic ozonation of micropollutants in wastewater. In this study, commercial Mg (OH)2 was used for the degradation of cyclophosphamide (CYP) by ozone. The crystal phase was confirmed by X-ray powder Diffraction (XRD). Percent degradation of 10 ppm CYP after 30 min by O3 and Mg (OH)2/O3 was 56 and 93, respectively, suggesting enhanced decomposition of O3 to ROS by the catalyst. The presence of ROS was further confirmed using pCBA as a probe, which showed that the concentration of ROS was eight times higher in the presence of Mg (OH)2/O3 than O3 alone. Catalytic ozonation experiments in the presence of scavengers showed that OH· radicals play a significant role in the degradation of CYP. The catalyst was found to be reusable for at least three cycles without significant loss in degradation efficiency. To study the compatibility of Mg (OH)2 for wastewater treatment applications, synthetic effluent was spiked with CYP and subjected to ozonation by Mg(OH)2/O3. The TOC of CYP before and after the treatment showed that Mg (OH)2/O3 not only degrades CYP but also mineralizes to a certain extent unlike O3 alone. Full article
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Article
A Deep Learning Method Based on Bidirectional WaveNet for Voltage Sag State Estimation via Limited Monitors in Power System
Energies 2022, 15(6), 2273; https://doi.org/10.3390/en15062273 - 21 Mar 2022
Viewed by 448
Abstract
Voltage sag state estimation on the basis of a limited number of installed monitors is essential to dividing the responsibility for the voltage sag and taking corresponding measurements for improvement in voltage quality. Therefore, a deep learning methodology via bidirectional WaveNet for the [...] Read more.
Voltage sag state estimation on the basis of a limited number of installed monitors is essential to dividing the responsibility for the voltage sag and taking corresponding measurements for improvement in voltage quality. Therefore, a deep learning methodology via bidirectional WaveNet for the voltage sag state estimation is proposed in this paper. The presented method can simultaneously estimate voltage sag state at non-monitored buses via limited monitors. Especially, the proposed deep learning method using the bidirectional WaveNet is designed to explore the long-term and long-range temporal dependencies in both the forward and backward directions. In this way, only by using original measured voltages through monitors, high accuracy for voltage sag state estimation can be achieved without restructured or redesign of the raw monitored data. An excellent advantage of the presented algorithm is that it can be implemented without system parameters or operating conditions or any other prior information. The presented methodology was verified by the IEEE 30-bus benchmark system. The experimental results illustrated that the accuracy of the voltage sag state estimation results was over 99.83%. Furthermore, a comparison among different models, including the bidirectional GRU-based model, one-way WaveNet-based model, and bidirectional WaveNet-based model, was also conducted. The results illustrated that the proposed bidirectional WaveNet-based model achieved the highest accuracy and quickest convergence speed. Full article
(This article belongs to the Section F5: Artificial Intelligence and Smart Energy)
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Article
Techno-Economic Analysis of Intermediate Pyrolysis with Solar Drying: A Chilean Case Study
Energies 2022, 15(6), 2272; https://doi.org/10.3390/en15062272 - 21 Mar 2022
Cited by 2 | Viewed by 670
Abstract
Intermediate pyrolysis can be used to obtain high-quality biofuels from low-value residues such as sewage sludge or digestate. A major obstacle is the high water content of sludgy biomass, which requires an energy-intensive and expensive drying step before pyrolysis. Solar greenhouse drying is [...] Read more.
Intermediate pyrolysis can be used to obtain high-quality biofuels from low-value residues such as sewage sludge or digestate. A major obstacle is the high water content of sludgy biomass, which requires an energy-intensive and expensive drying step before pyrolysis. Solar greenhouse drying is an efficient and sustainable alternative to a thermally heated belt dryer. In this study, a techno-economic assessment of intermediate pyrolysis with solar drying is carried out. Marketable products of the process are bio-oil, a substitute for diesel or heating oil, and bio-char with various possible applications. Chile is chosen as the setting of the study as its 4000 km long extension from north to south gives the opportunity to evaluate different locations and levels of solar irradiation. It is found that solar drying results in higher capital investment, but lower fuel costs. Depending on the location and solar irradiation, solar drying can reduce costs by 5–34% compared to belt drying. The break-even price of bio-char is estimated at 300–380 EUR/ton after accounting for the revenue from the liquid bio-oil. Full article
(This article belongs to the Special Issue Biofuel Value Chains: Innovations and Sustainability)
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