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Energies, Volume 15, Issue 21 (November-1 2022) – 503 articles

Cover Story (view full-size image): Li-Ion batteries are the dominant power source propelling our society. Optimization of the electrode and cell designs as well as the corresponding production processes is of paramount importance. This paper presents a virtual approach comprising both data-driven and simulation-based techniques. A large set of virtual microstructures with different particle sizes and active and passive material content is generated and morphologically analyzed. Electrochemical simulations are informed by this analysis and link structural properties to electrochemical performance focusing on the role of passive materials in high-energy batteries. The methodology provides an efficient prediction tool for the optimization of electrode formulations and designs. View this paper
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Article
Analysis of the Simulation of the Operation of a Wheel Hub Motor Mounted in a Hybrid Drive of a Delivery Vehicle
Energies 2022, 15(21), 8323; https://doi.org/10.3390/en15218323 - 07 Nov 2022
Cited by 1 | Viewed by 724
Abstract
The article presents the analysis of operational parameters and thermal analysis of the wheel hub motor during operation in the car drive. The authors proposed an analysis of the operation of the wheel hub motor mounted in a hybrid car, during Artemis driving [...] Read more.
The article presents the analysis of operational parameters and thermal analysis of the wheel hub motor during operation in the car drive. The authors proposed an analysis of the operation of the wheel hub motor mounted in a hybrid car, during Artemis driving cycles and while driving on the road with different slopes. The simulations were carried out in the Ansys Motor-CAD program. The calculations are based on coupled models of the electromagnetic circuit and thermal models of the motor. The conducted research is a proposal of an approach to the design of electric vehicle propulsion motors, which allows us to consider problems related to predicting at the motor design stage what are its possibilities and what risks during operation in a real drive. The analysis also includes the impact of the applied motor control strategy and the variation of the supply voltage. These are aspects that are extremely important in wheel hub motors, as they are weight-optimized motors with a limited volume and a relatively high power and torque density. Full article
(This article belongs to the Topic Advanced Electrical Machines and Drives Technologies)
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Article
On the Kinetic Mechanisms of the Reduction and Oxidation Reactions of Iron Oxide/Iron Pellets for a Hydrogen Storage Process
Energies 2022, 15(21), 8322; https://doi.org/10.3390/en15218322 - 07 Nov 2022
Cited by 1 | Viewed by 563
Abstract
This work aims at investigating the kinetic mechanisms of the reduction/oxidation (redox) reactions of iron oxide/iron pellets under different operating conditions. The reaction principle is the basis of a thermochemical hydrogen storage system. To simulate the charging phase, a single pellet consisting of [...] Read more.
This work aims at investigating the kinetic mechanisms of the reduction/oxidation (redox) reactions of iron oxide/iron pellets under different operating conditions. The reaction principle is the basis of a thermochemical hydrogen storage system. To simulate the charging phase, a single pellet consisting of iron oxide (90% Fe2O3, 10% stabilising cement) is reduced with different hydrogen (H2) concentrations at temperatures between 600 and 800 °C. The discharge phase is initiated by the oxidation of the previously reduced pellet by water vapour (H2O) at different concentrations in the same temperature range. In both reactions, nitrogen (N2) is used as a carrier gas. The redox reactions have been experimentally measured in a thermogravimetric analyser (TGA) at a flow rate of 250 mL/min. An extensive literature review has been conducted on the existing reactions’ kinetic mechanisms along with their applicability to describe the obtained results. It turned out that the measured kinetic results can be excellently described with the so-called shrinking core model. Using the geometrical contracting sphere reaction mechanism model, the concentration- and temperature-dependent reduction and oxidation rates can be reproduced with a maximum deviation of less than 5%. In contrast to the reduction process, the temperature has a smaller effect on the oxidation reaction kinetics, which is attributed to 71% less activation energy (Ea,Re=56.9 kJ/mol versus Ea,Ox=16.0 kJ/mol). The concentration of the reacting gas showed, however, an opposite trend: namely, to have an almost twofold impact on the oxidation reaction rate constant compared to the reduction rate constant. Full article
(This article belongs to the Section A5: Hydrogen Energy)
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Article
Extension and Correction of Budeanu Power Theory Based on Currents’ Physical Components (CPC) Theory for Single-Phase Systems
Energies 2022, 15(21), 8321; https://doi.org/10.3390/en15218321 - 07 Nov 2022
Viewed by 446
Abstract
In 1927, the most recognized power theory in the frequency domain was proposed by Budeanu. The second power theory in the frequency domain, which is currently catching a lot of supporters, is the approach proposed by Czarnecki. Both theories have common features in [...] Read more.
In 1927, the most recognized power theory in the frequency domain was proposed by Budeanu. The second power theory in the frequency domain, which is currently catching a lot of supporters, is the approach proposed by Czarnecki. Both theories have common features in the form of the description of active power and are completely different in terms of the description and interpretation of reactive power. This article presents the possibility of using mutual elements of both approaches: thus, it is possible to interpret the physical meaning of the reactive power (reactive current) proposed by Budeanu and the power before the deformation obtained from the mathematical description. Full article
(This article belongs to the Topic Power Quality)
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Article
Experimental Investigation of Two-Phase Flow Distribution with Different Vertical Header Configurations
Energies 2022, 15(21), 8320; https://doi.org/10.3390/en15218320 - 07 Nov 2022
Viewed by 429
Abstract
In this study, we investigated the behavior of two-phase flow distribution inside a vertical header of a microchannel heat exchanger (MCHX) that functions as an evaporator of a heat pump system. In general, the two-phase flow distribution behavior of the refrigerant differs depending [...] Read more.
In this study, we investigated the behavior of two-phase flow distribution inside a vertical header of a microchannel heat exchanger (MCHX) that functions as an evaporator of a heat pump system. In general, the two-phase flow distribution behavior of the refrigerant differs depending on the target application, which ranges from small-scale automobile air-conditioners to large-scale building heat pump systems. Particularly, it is reported that the distribution characteristics in the vertical header of the MCHX vary extensively according to the inlet flow conditions of the refrigerant and the physical profile of the header. In this study, the physical configurations (header height, branch tube diameter) of four types of vertical headers were considered. Thereafter, the operating conditions in an experimental device that simulates an MCHX with a vertical header were selected. The experiment was performed under R410A as the working fluid, with a saturation temperature of 15 °C, inlet mass flow rate of 50–150 kg h−1 (mass flux of 908–2723 kg m−2 s−1), and an inlet vapor quality of 0.1–0.2. The liquid and vapor flow ratios and the relative standard deviation were adopted as metrics to characterize the uniformity of flow distribution. The distribution characteristics were subsequently described according to Reynolds and Froude numbers. The larger the Reynolds number and the smaller the Froude number, the more uniform the two-phase flow distribution becomes. A correlation was proposed as a function of the Reynolds and Froude numbers to predict the flow distribution characteristics for the considered vertical headers. Full article
(This article belongs to the Section J: Thermal Management)
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Article
Inductive Power Transfer Battery Charger with IR-Based Closed-Loop Control
Energies 2022, 15(21), 8319; https://doi.org/10.3390/en15218319 - 07 Nov 2022
Viewed by 835
Abstract
A wireless battery charger with inductive power transfer (IPT) was proposed in this paper. The commonly used constant-current constant-voltage (CC-CV) charging method is accomplished by a closed-loop controlled IPT with a hybrid resonant circuit on the secondary side. A smooth transition between the [...] Read more.
A wireless battery charger with inductive power transfer (IPT) was proposed in this paper. The commonly used constant-current constant-voltage (CC-CV) charging method is accomplished by a closed-loop controlled IPT with a hybrid resonant circuit on the secondary side. A smooth transition between the CC stage and the CV stage can be made simply by swapping exactly the associated switches on resonant capacitors. The required charging voltage and current are regulated by controlling the phase-shifted angle of the high-frequency inverter on the primary side. To stabilize the charging current and voltage, a closed-loop digital controller was introduced with infrared (IR) transmission feedback. Precise regulation of the resonant inverter on a relative small ranged phase-shifted angle can be realized by two 16-bit microcontroller units (MCUs) with compact encoding and decoding techniques. A hybrid resonant inverter was designed for a 600 W prototype of the proposed IPT battery charger. Experimental results from exemplar cases have demonstrated that the battery charger can provide a stable charging current at the CC stage and then transit smoothly into the CV stage. Full article
(This article belongs to the Topic IOT, Communication and Engineering)
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Article
Numerical Study on the Effects of Water and Heat Transport on Two-Phase Flow in a Polymer Electrolyte Membrane Fuel Cell
Energies 2022, 15(21), 8318; https://doi.org/10.3390/en15218318 - 07 Nov 2022
Cited by 1 | Viewed by 816
Abstract
A one-dimensional transient non-isothermal model was developed to study the two-phase flow phenomenon in a polymer electrolyte membrane fuel cell. The model focused on the phase change between vapor and liquid water, and the transport of oxygen, hydrogen, water, and heat. The cell [...] Read more.
A one-dimensional transient non-isothermal model was developed to study the two-phase flow phenomenon in a polymer electrolyte membrane fuel cell. The model focused on the phase change between vapor and liquid water, and the transport of oxygen, hydrogen, water, and heat. The cell was discretized into 39 control volumes, and the finite volume method and the iteration method were used to solve the transport equations. The variations in the state parameters of the model during fuel cell operations were analyzed. The results showed that, when the inlet gas humidity was high, the vapor tended to condense in gas diffusion layer regions close to the gas channel. As temperatures in these regions were low, the vapor was more likely to condense. Liquid water appeared latest in the middle of the anode gas diffusion layer, because the vapor concentration in this area is always lower than its saturated value. A higher operating temperature in a cell is beneficial to prevent flooding at the cathode. Full article
(This article belongs to the Collection Batteries, Fuel Cells and Supercapacitors Technologies)
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Article
Entropy Analysis of EMHD Hybrid Nanofluid Stagnation Point Flow over a Porous Stretching Sheet with Melting Heat Transfer in the Presence of Thermal Radiation
Energies 2022, 15(21), 8317; https://doi.org/10.3390/en15218317 - 07 Nov 2022
Viewed by 521
Abstract
In this study, the entropy formation of an electromagnetohydrodynamic hybrid nanofluid at a stagnation point flow towards a stretched surface in the presence of melting heat transfer, second-order slip, porous medium, viscous dissipation and thermal radiation are investigated. Hybrid nanoparticles alumina (Al2 [...] Read more.
In this study, the entropy formation of an electromagnetohydrodynamic hybrid nanofluid at a stagnation point flow towards a stretched surface in the presence of melting heat transfer, second-order slip, porous medium, viscous dissipation and thermal radiation are investigated. Hybrid nanoparticles alumina (Al2O3) and copper (Cu) are considered, with the base fluid water (H2O). Similarity transformations are used to address the governing partial differential equations (PDEs) that lead to the corresponding ordinary differential equations. The resulting ODEs are solved by employing bvp4c solver numerically in the MATLAB package. The effects of temperature, transport, production of entropy and Bejan number Be are graphically exhibited. Higher radiation parameters R and an electric field E lead to an increase in fluid temperature. The velocity boundary layer is lowered by the magnetic field and porous media parameters. The opposite behaviour is observed in the electric field E. As a result, hybrid nanofluid has numerous uses in engineering cosmetics, automotive industry, home industry, for cancer treatment, food packaging, pharmaceuticals, fabrics, paper plastics, paints, ceramics, food colorants, electronics, heat exchangers, water purification, lubricants and soaps as well. Full article
(This article belongs to the Section J1: Heat and Mass Transfer)
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Review
Thermal Management Technologies Used for High Heat Flux Automobiles and Aircraft: A Review
Energies 2022, 15(21), 8316; https://doi.org/10.3390/en15218316 - 07 Nov 2022
Viewed by 743
Abstract
In recent years, global automotive industries are going through a significant revolution from traditional internal combustion engine vehicles (ICEVs) to electric vehicles (EVs) for CO2 emission reduction. Very similarly, the aviation industry is developing towards more electric aircraft (MEA) in response to [...] Read more.
In recent years, global automotive industries are going through a significant revolution from traditional internal combustion engine vehicles (ICEVs) to electric vehicles (EVs) for CO2 emission reduction. Very similarly, the aviation industry is developing towards more electric aircraft (MEA) in response to the reduction in global CO2 emission. To promote this technology revolution and performance advancement, plenty of electronic devices with high heat flux are implemented on board automobiles and aircraft. To cope with the thermal challenges of electronics, in addition to developing wide bandgap (WBG) semiconductors with satisfactory electric and thermal performance, providing proper thermal management solutions may be a much more cost-effective way at present. This paper provides an overview of the thermal management technologies for electronics used in automobiles and aircraft. Meanwhile, the active methods include forced air cooling, indirect contact cold plate cooling, direct contact baseplate cooling, jet impingement, spray cooling, and so on. The passive methods include the use of various heat pipes and PCMs. The features, thermal performance, and development tendency of these active and passive thermal management technologies are reviewed in detail. Moreover, the environmental influences introduced by vibrations, shock, acceleration, and so on, on the thermal performance and reliability of the TMS are specially emphasized and discussed in detail, which are usually neglected in normal operating conditions. Eventually, the possible future directions are discussed, aiming to serve as a reference guide for engineers and promote the advancement of the next-generation electronics TMS in automobile and aircraft applications. Full article
(This article belongs to the Special Issue Advanced Thermal Management and Cooling Technologies)
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Article
Ruddlesden–Popper Oxides LaSrM11−xM2xO4±δ (M1, M2—Fe, Co, Ni) Synthesized by the Spray-Pyrolysis Method as Promising Electrocatalysts for Oxygen Evolution Reaction
Energies 2022, 15(21), 8315; https://doi.org/10.3390/en15218315 - 07 Nov 2022
Viewed by 621
Abstract
Ruddlesden–Popper (RP) transition-metal oxide phases with the general formula An+1BnO3n+1 are versatile functional materials that can accommodate a large variety of compositions without compromising structural stability. Substitutions at the A and B sites allow for [...] Read more.
Ruddlesden–Popper (RP) transition-metal oxide phases with the general formula An+1BnO3n+1 are versatile functional materials that can accommodate a large variety of compositions without compromising structural stability. Substitutions at the A and B sites allow for the precise control of functional properties of these materials. This opens wide possibilities for rational design. In particular, some of these materials were demonstrated to be efficient and stable catalysts for electrochemical oxygen evolution reaction (OER)—one of the key processes in fuel cells and water electrolyzers. In this work, RP phases LaSrM11−xM2xO4±δ (M1, M2—Fe, Co, Ni) with unreported stoichiometry are prepared from aqueous solutions of metal nitrates using the ultrasonic spray-pyrolysis (USP) technique. We found that the phase purity of samples synthesized by USP is higher as compared to samples prepared by solid-state synthesis or by precipitation from aqueous solutions followed by calcination, used in previous studies of RP oxides. LaSrFe0.5Ni0.5O4–δ (LSNF) oxides are found to be very active in OER in alkaline solutions, with overpotential 0.27 V at j = 0.1 A cm–2 of visible electrode surface in a 5 M solution of KOH. This overpotential is on par with the noble-metal-based OER electrocatalysts. Moreover, the catalytic performance of LSNF in OER is found to be stable over the electrolysis time even in the strongly alkaline solution. These two factors let us conduct the water splitting process in more concentrated electrolytes decreasing the energy cost of hydrogen production by water electrolysis. Full article
(This article belongs to the Special Issue Flow Systems for Electrical Energy Conversion)
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Article
Effects of Hot Pressing Temperature and Pressure on Dielectric Properties of Aramid Insulating Paper
Energies 2022, 15(21), 8314; https://doi.org/10.3390/en15218314 - 07 Nov 2022
Viewed by 404
Abstract
The hot pressing parameters and fiber ratio have an important influence on the dielectric properties of aramid insulating paper. In order to deeply explore its influence and the mechanism behind it, aramid insulating papers were made with different hot pressing temperatures and pressures [...] Read more.
The hot pressing parameters and fiber ratio have an important influence on the dielectric properties of aramid insulating paper. In order to deeply explore its influence and the mechanism behind it, aramid insulating papers were made with different hot pressing temperatures and pressures as well as fiber ratios. Its tightness, dielectric constant, and AC breakdown strength were tested, and its microstructure was analyzed by scanning electron microscopy. It was found that with an increase in hot pressing temperature, pressure, and fibrid content, the overall dielectric constant of the insulating paper showed a slight upward trend, while the tightness and AC breakdown strength continued to increase. Hot pressing temperature and pressure have a synergistic effect on the dielectric properties of insulating paper. The effects of these two parameters on the dielectric properties of insulating paper are similar, while the AC breakdown strength is greatly affected by the fiber ratio. In this paper, the influence mechanism by which the microstructure and fiber crystallinity of insulating paper is affected in the hot pressing process is discussed. Full article
(This article belongs to the Special Issue Advances in High Voltage Engineering)
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Review
Energy Saving by Parametric Optimization and Advanced Lubri-Cooling Techniques in the Machining of Composites and Superalloys: A Systematic Review
Energies 2022, 15(21), 8313; https://doi.org/10.3390/en15218313 - 07 Nov 2022
Cited by 1 | Viewed by 649
Abstract
The resources of the earth are being consumed day by day with the increasing population and necessities of humankind in many areas, such as industrial applications and basic needs in houses, workplaces and transportation. As a consequence, careful usage of the energy sources [...] Read more.
The resources of the earth are being consumed day by day with the increasing population and necessities of humankind in many areas, such as industrial applications and basic needs in houses, workplaces and transportation. As a consequence, careful usage of the energy sources and the conversed energy is of great importance in order to obtain sustainable development. Machining operations have a large percentage of all manufacturing methods in terms of depleted energy which gives them a high potential for reducing the total energy consumption. The approaches handled in the literature for the minimization of the consumed energy in the machining industry were considered in this study. While several machinability characteristics under different machining processes were investigated broadly in the context of composites and superalloys, the comparison of these systems has been given cursory attention in the current literature, specifically for cutting energy saving. The overall performance of these group material systems utilizing widely in numerous significant industrial areas supplies important signs about manufacturing costs, service conditions and environmental impacts. It is highly crucial to monitor the indicators of energy-saving phenomena of the machined parts since the mechanisms behind the energy consumption of these systems is very complex and dynamic owing to different process-induced variables. This well-organized review paper distinguishes itself from previous studies in this field since the comprehensive literature survey paves the way for diverse approaches that regard energy saving, especially for composites and superalloys under different machining operations. This overview paper aims to contribute to the current literature by highlighting the effects of the state-of-the-art approaches in reducing energy consumption in the machining of industrially important materials. This study can also establish a framework in the context of the process-property interactions to comprehend the influence of energy-saving mechanisms through machining in a system of interest. Full article
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Review
Roof Fall Hazard Monitoring and Evaluation—State-of-the-Art Review
Energies 2022, 15(21), 8312; https://doi.org/10.3390/en15218312 - 07 Nov 2022
Cited by 1 | Viewed by 616
Abstract
A roof fall hazard is still one of the major threats in the underground mining industry. Each such type of event always brings great risk to miners and causes serious interruptions in the process of rock excavation. In general, the possibility of roof [...] Read more.
A roof fall hazard is still one of the major threats in the underground mining industry. Each such type of event always brings great risk to miners and causes serious interruptions in the process of rock excavation. In general, the possibility of roof fall hazard occurrence is directly related to the local geology, the presence of horizontal stresses as well as the type of excavation method and the efficacy of the utilized roof support. Due to the complexity of this process, it is important to continuously evaluate the roof fall risk, especially in long life-time places where a mining crew is often present. Within this article, a detailed review of the current methods of monitoring and evaluating roof fall risk was presented. Based on the extensive literature survey, different types of devices were described, and their advantages and disadvantages were pointed out. Furthermore, new trends in the area of roof fall risk monitoring were described and discussed. Full article
(This article belongs to the Topic Advanced Systems Engineering: Theory and Applications)
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Article
Slope Stability Numerical Analysis and Landslide Prevention of Coal Mine Waste Dump under the Impact of Rainfall—A Case Study of Janina Mine, Poland
Energies 2022, 15(21), 8311; https://doi.org/10.3390/en15218311 - 07 Nov 2022
Viewed by 536
Abstract
In Poland, the mining waste from underground coal mines is commonly deposited in surface dump sites, forming slopes or piles of materials dozens of meters high. Because of the loose structure of a mine waste dump slope, landslides may occur after a heavy [...] Read more.
In Poland, the mining waste from underground coal mines is commonly deposited in surface dump sites, forming slopes or piles of materials dozens of meters high. Because of the loose structure of a mine waste dump slope, landslides may occur after a heavy rainfall. This requires significant labor costs in reforming the mine waste dump sites and disturbs the continuity of the depositing operations. Moreover, if the mine waste dump sites located in the built-up areas, such as in the Janina mine waste dump, landslides apparently can threaten even lives and properties. Therefore, a mine waste dump stability analysis is necessary for ensuring safety. In this paper, slope stability analysis was conducted using numerical modeling under the impact of rainfall for the Janina mine waste dump, located in Libiąż, Poland. The results indicated that slope tends to loose stability in case of high rainfall intensity and short duration. Then, slope reinforcement using soil nailing and steel mesh was proposed to prevent landslide under the impact of high rainfall intensity. Once again, slope stability analysis was carried out with selected reinforcement. Meanwhile, slope monitoring was performed to assess the slope reinforcement implementation at the Janina mine waste dumps against the impact of high rainfall intensity. Based on the modeling and monitoring outcomes, assessments of slope stability and selected landslide prevention measures for the Janina mine waste dump under the impact of rainfall were presented. Full article
(This article belongs to the Special Issue Coal Mining)
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Article
The CROWDTHERMAL Project: Creating Public Acceptance of Geothermal Energy and Opportunities for Community Financing
Energies 2022, 15(21), 8310; https://doi.org/10.3390/en15218310 - 07 Nov 2022
Viewed by 557
Abstract
One of the major challenges regarding energy transition is to create active support towards renewable energy installations on a local level. The CROWDTHERMAL project presents practical approaches for involving local stakeholders in different measures in order to develop acceptable solutions. Based on technical [...] Read more.
One of the major challenges regarding energy transition is to create active support towards renewable energy installations on a local level. The CROWDTHERMAL project presents practical approaches for involving local stakeholders in different measures in order to develop acceptable solutions. Based on technical evidence and data from concrete case studies, the project shows ways how community funding can increase social acceptance towards geothermal energy installations. The presented solutions are based on alternative financial schemes studies and risk mitigation analysis in geothermal projects. Full article
(This article belongs to the Special Issue The Advancement of Geothermal Energy Utilisation by New Developments)
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Review
Gas Hydrate-Based CO2 Capture: A Journey from Batch to Continuous
Energies 2022, 15(21), 8309; https://doi.org/10.3390/en15218309 - 07 Nov 2022
Cited by 1 | Viewed by 701
Abstract
Future carbon dioxide capture and storage (CCS) will be impacted by the new scenario in which the energy supply rapidly shifts from oil-based to natural gas-based means, but this shift also presents an opportunity to utilize natural gas hydrates (NGHs). This review discusses [...] Read more.
Future carbon dioxide capture and storage (CCS) will be impacted by the new scenario in which the energy supply rapidly shifts from oil-based to natural gas-based means, but this shift also presents an opportunity to utilize natural gas hydrates (NGHs). This review discusses the present state of CCS research and development, the advantages of the various approaches, and the barriers to commercialization that exist today. It also provides an evaluation of certain practical small- and large-scale CCS applications. The high initial investment, as well as ongoing maintenance costs, plague today’s commercially accessible CO2 capture technologies, including absorption, adsorption, membranes, and cryogenic separation. Gas hydrate-based capture has the potential to become the dominant method for CO2 separation because of the high recovery rates and purity it provides. Hydrate-based technologies, including CO2 capture, CO2 separation, and transportation, can also be used to reduce greenhouse gas emissions and have excellent application potential. Despite this, the potential of technology based on gas hydrates to help reduce the effects of climate change in the future has received little attention. This study discusses cosmopolitan energy provision and environmental challenges and conversions, and the role of gas hydrates in the carbon cycle. This paper summarizes the state-of-the-art developments in hydrate-based reactors, thereby providing a perspective on the roles of NGHs in the future energy supply and climate change mitigation. In all these areas, we focus on identifying future CCS challenges and the technological development risk in gas hydrate-based systems, which should be highlighted in the next several decades. Full article
(This article belongs to the Special Issue Carbon Capture, Utilisation and Storage)
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Article
Operation of an Energy Storage System Integrated with a Photovoltaic System and an Industrial Customer under Different Real and Pseudo-Real Profiles
Energies 2022, 15(21), 8308; https://doi.org/10.3390/en15218308 - 07 Nov 2022
Viewed by 438
Abstract
This article presents an idea of the implementation of different real load profiles for energy storage system (ESS) operation. The considered approaches are based on real long-term measurements using energy meters, the adaptation of the standard profiles defined by the distribution system operator [...] Read more.
This article presents an idea of the implementation of different real load profiles for energy storage system (ESS) operation. The considered approaches are based on real long-term measurements using energy meters, the adaptation of the standard profiles defined by the distribution system operator (DSO), as well as a mix of the level of contracted power and short-term measurements. All combinations are used as electricity demand to formulate an ESS operation plan that cooperates with the PV system and the electricity market. The GAMS solver is applied to obtain optimal operation tasks of the ESS to cover different real and pseudo-real load profiles of an industrial company. Obtained results are presented using a real case study of a metallurgy company with a 317 kWp photovoltaic installation and a 200 kW ESS. Full article
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Review
Review of PV Solar Energy Development 2011–2021 in Central European Countries
Energies 2022, 15(21), 8307; https://doi.org/10.3390/en15218307 - 07 Nov 2022
Cited by 2 | Viewed by 625
Abstract
According to the data collected in 2022 during 5th International Off-Grid Renewable Energy Conference organized in Abu Dhabi by the International Renewable Energy Agency, the global energy requirements show a negative impact on approximately 785 million people facing energy poverty. The long-term energy [...] Read more.
According to the data collected in 2022 during 5th International Off-Grid Renewable Energy Conference organized in Abu Dhabi by the International Renewable Energy Agency, the global energy requirements show a negative impact on approximately 785 million people facing energy poverty. The long-term energy sustainability solutions should consider off-grid solutions in the planning of an energy mix and be considered as interim both in remote and already urbanized areas. These measures require integrated planning and partnering with local distribution networks. The review presents the development of photovoltaic installations in Central European countries. For more than 40 years, this area belonged to different regimes and joined the European Union at various dates. Hence, the development of energy policies and cultural and social expectations differ even when based on the Green Deal presented by the European Union in 2020. The outcomes prove that even with a variety of policy measures, the strongest boost can be given only by a set of national rules and financial incentives supporting the stakeholders. It should be noted that the advancement of PV often does not rely on climatic conditions, but more on the level of incentives undertaken by each country, as well as the general policy measures undertaken on the EU level. Full article
(This article belongs to the Special Issue Modern Technologies for Renewable Energy Development and Utilization)
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Communication
Potential Solutions for the Short to Medium-Term Natural Gas Shortage Issues of Europe: What Can Qatar Do?
Energies 2022, 15(21), 8306; https://doi.org/10.3390/en15218306 - 07 Nov 2022
Cited by 1 | Viewed by 750
Abstract
European countries are required to look for alternative gas suppliers to deliver energy security for Europe. Qatar has been proposed to be an alternative gas supplier; however, there are problems that limit Qatar from exporting more gas to Europe, namely: the limited LNG [...] Read more.
European countries are required to look for alternative gas suppliers to deliver energy security for Europe. Qatar has been proposed to be an alternative gas supplier; however, there are problems that limit Qatar from exporting more gas to Europe, namely: the limited LNG quantities available for export, the long-term fixed contracting strategy, and the lack of room to receive additional gas in European LNG terminals. As these problems are critical and limit Qatar from exporting more gas to Europe, this research aims to propose potential solutions to overcome them. The results show that to solve the issue of the limited LNG quantities available for export, Qatar can produce electricity from renewable sources and export the gas consumed for power production, and can produce renewable natural gas (RNG) from green hydrogen and captured carbon dioxide. Two BCM of natural gas can be exported if 15% of the electricity required is produced from renewables in Qatar. In addition, 0.45 BCM of RNG can be exported if Qatar uses its natural resources to produce 5000 MW of renewable power. Redirecting contracts coming to an end and increasing dependence on spot markets can resolve the issue of a long-term fixed contracting strategy. Finally, using floating import terminals may alleviate the problem of European LNG terminals running out of room to receive more gas. Full article
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Article
An Optimization Method for a Compressor Standby Scheme Based on Reliability Analysis
Energies 2022, 15(21), 8305; https://doi.org/10.3390/en15218305 - 07 Nov 2022
Viewed by 445
Abstract
The reliability of the compressor system determines the gas supply safety. An important method to improve the reliability is to set up standby compressors in stations, conducted by the standby compressor or power. A lack of quantitative assessments of standby compressors often results [...] Read more.
The reliability of the compressor system determines the gas supply safety. An important method to improve the reliability is to set up standby compressors in stations, conducted by the standby compressor or power. A lack of quantitative assessments of standby compressors often results in more spare compressors or power than actually needed, which wastes money. In this study, a reliability-based method is proposed to determine the numbers and positions of the standby compressors, which can reduce investments, and ensure reliability. Firstly, Monte Carlo method was used to calculate the compressor outage probability of the whole pipeline, respectively, through which the initial number of standby compressors was obtained. Further, the standby schemes were designed, in which the positions of the failed compressors were obtained by the Monte Carlo simulation. Moreover, the worst situation in which the compressors were shut down was used to test the standby scheme, calculating the flow reliability, pressure boundary, and total power. Finally, using the Xin–Yue–Zhe pipeline as a case study, the results indicate that the number of standby compressors in the improved schemes was reduced by seven and the pipeline reliability reached 96.86%. Full article
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Article
Energy-Aware UAV Based on Blockchain Model Using IoE Application in 6G Network-Driven Cybertwin
Energies 2022, 15(21), 8304; https://doi.org/10.3390/en15218304 - 07 Nov 2022
Cited by 1 | Viewed by 656
Abstract
Several advanced features exist in fifth-generation (5G) correspondence than in fourth-generation (4G) correspondence. Centric cloud-computing architecture achieves resource sharing and effectively handles big data explosion. For data security problems, researchers had developed many methods to protect data against cyber-attacks. Only a few solutions [...] Read more.
Several advanced features exist in fifth-generation (5G) correspondence than in fourth-generation (4G) correspondence. Centric cloud-computing architecture achieves resource sharing and effectively handles big data explosion. For data security problems, researchers had developed many methods to protect data against cyber-attacks. Only a few solutions are based on blockchain (BC), but are affected by expensive storage costs, network latency, confidence, and capacity. Things are represented in digital form in the virtual cyberspace which is the major responsibility of the communication model based on cybertwin. A novel cybertwin-based UAV 6G network architecture is proposed with new concepts such as cloud operators and cybertwin in UAV. Here, IoE applications have to be energy aware and provide scalability with less latency. A novel Compute first networking (CFN) framework named secure blockchain-based UAV communication (BC-UAV) is designed which offers network services such as computing, caching, and communication resources. The focus of the blockchain was to improve the security in the cloud using hashing technique. Edge clouds support core clouds to quickly respond to user requests. Full article
(This article belongs to the Special Issue Energy Efficiency in Wireless Networks)
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Article
Solution of Probabilistic Optimal Power Flow Incorporating Renewable Energy Uncertainty Using a Novel Circle Search Algorithm
Energies 2022, 15(21), 8303; https://doi.org/10.3390/en15218303 - 07 Nov 2022
Cited by 1 | Viewed by 485
Abstract
Integrating renewable energy sources (RESs) into modern electric power systems offers various techno-economic benefits. However, the inconsistent power profile of RES influences the power flow of the entire distribution network, so it is crucial to optimize the power flow in order to achieve [...] Read more.
Integrating renewable energy sources (RESs) into modern electric power systems offers various techno-economic benefits. However, the inconsistent power profile of RES influences the power flow of the entire distribution network, so it is crucial to optimize the power flow in order to achieve stable and reliable operation. Therefore, this paper proposes a newly developed circle search algorithm (CSA) for the optimal solution of the probabilistic optimal power flow (OPF). Our research began with the development and evaluation of the proposed CSA. Firstly, we solved the OPF problem to achieve minimum generation fuel costs; this used the classical OPF. Then, the newly developed CSA method was used to deal with the probabilistic power flow problem effectively. The impact of the intermittency of solar and wind energy sources on the total generation costs was investigated. Variations in the system’s demands are also considered in the probabilistic OPF problem scenarios. The proposed method was verified by applying it to the IEEE 57-bus and the 118-bus test systems. This study’s main contributions are to test the newly developed CSA on the OPF problem to consider stochastic models of the RESs, providing probabilistic modes to represent the RESs. The robustness and efficiency of the proposed CSA in solving the probabilistic OPF problem are evaluated by comparing it with other methods, such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and the hybrid machine learning and transient search algorithm (ML-TSO) under the same parameters. The comparative results showed that the proposed CSA is robust and applicable; as evidence, an observable decrease was obtained in the costs of the conventional generators’ operation, due to the penetration of renewable energy sources into the studied networks. Full article
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Article
Numerical and Experimental Study on Combustion Characteristics of Micro-Gas Turbine Biogas Combustor
Energies 2022, 15(21), 8302; https://doi.org/10.3390/en15218302 - 07 Nov 2022
Cited by 1 | Viewed by 480
Abstract
The use of biogas in land-based gas turbines for power generation is a promising approach to reducing greenhouse gases and our dependence on fossil fuels. The focus of this research was to investigate the fuel/air mixing and combustion performance in an DLE (dry [...] Read more.
The use of biogas in land-based gas turbines for power generation is a promising approach to reducing greenhouse gases and our dependence on fossil fuels. The focus of this research was to investigate the fuel/air mixing and combustion performance in an DLE (dry low emission) type can combustor designed for a micro-gas turbine. The fuel and air mixing uniformity was studied considering the air flow characteristic and fuel injection performance through the numerical simulation. The influence of the fuel/air mixing characteristics on the combustion characteristics was studied by numerical simulation and experimental tests. The combustion characteristics studied included the temperature field in the combustor, the pattern factor at the combustor outlet, combustion efficiency, and pollutant emission characteristics. The results show the position of the fuel nozzle has little effect on the mixing uniformity due to the limited mixing space for the micro-gas turbine combustor, while there are optimal fuel nozzle diameters to generate the suitable fuel jet momentum for the mixing process. The fuel/air mixing characteristics had an obvious influence on the combustion performance for the studied DLE combustor. The increase in the fuel air mixing uniformity can decrease the NOx emissions and generate a better temperature distribution at the combustor outlet. The increased mixing uniformity may decrease the combustion efficiency and increase the CO emissions of the micro-gas turbine combustor. Full article
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Article
Internet Users’ Approach to HRM Portals in the Context of Sustainable Development—A Comparative Analysis of Poland and Türkiye
Energies 2022, 15(21), 8301; https://doi.org/10.3390/en15218301 - 07 Nov 2022
Viewed by 485
Abstract
The purpose of this article was to identify the characteristics of HRM (Human Resources Management) portals that can contribute to building a smart, sustainable society in two countries: Poland and Türkiye. The analyzed countries were selected due to their similar economic situation, as [...] Read more.
The purpose of this article was to identify the characteristics of HRM (Human Resources Management) portals that can contribute to building a smart, sustainable society in two countries: Poland and Türkiye. The analyzed countries were selected due to their similar economic situation, as well as differences in terms of culture and customs and varying degrees of ICT (Information and Communications Technology) implementation in the economy. Conducting the survey at this particular moment was intended to objectivize users’ opinions on the HRM portals and their attributes that may contribute to mitigating the effects of the crisis and facilitating economic development toward the creation of a sustainable society. The survey was conducted in April 2022. It was carried out in both countries and covered a group of more than 850 respondents. The CAWI (Computer Assisted Web Interview) method was used in the survey. The differences between results were identified, and the degree of verification of the hypothesis was established and discussed in this paper. In the first stage of the study, the respondents’ environment was examined, as well as their opinions on the use of HRM portals. The second phase consisted of assessing the attributes of the most well-known HRM portals that can contribute to building a smart, sustainable industry. As a result, the finally distinguished features included the characteristics that were most important to the users of the portals and those that supported the development of HRM portals due to their innovativeness. The study fills the research gap regarding the potential impact of HRM portals and their prospective use in first restoring the economic balance of a sustainable society. Full article
(This article belongs to the Special Issue Sustainable Development: Policies, Challenges, and Further)
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Review
The Comprehensive Overview of Large-Volume Surfactant Slugs Injection for Enhancing Oil Recovery: Status and the Outlook
Energies 2022, 15(21), 8300; https://doi.org/10.3390/en15218300 - 07 Nov 2022
Cited by 2 | Viewed by 524
Abstract
Despite the development of alternative energy sources, oil and gas still remain the predominant energy sources in most countries in the world. Due to gradual hydrocarbon reserve depletion and the existing downward trend in the production level, there is a need to search [...] Read more.
Despite the development of alternative energy sources, oil and gas still remain the predominant energy sources in most countries in the world. Due to gradual hydrocarbon reserve depletion and the existing downward trend in the production level, there is a need to search for methods and technical approaches to level off the falling rates. Chemically enhanced oil recovery methods (EOR) by surfactant solution injections are one of the possible approaches for addressing this issue in already developed fields. Most often, surfactants are injected together with polymers or alkalis. These technologies are called surfactant–polymer (SP) and alkali–surfactant–polymer (ASP) flooding. Basically, SP and ASP have been distributed in China and Canada. In this article, in addition to these countries, we paid attention to the results of pilot and full-scale tests of SP and ASP in Russia, Hungary, and Oman. This study was a comprehensive overview of laboratory and field tests of surfactant solutions used for oil displacement in SP and ASP technologies. The first part of the article discussed the physical fundamentals of the interaction of oil with surfactants. The second part presented the main chemical reagents used to increase oil recovery. In the third part, we described the main facilities used for the preparation and injection of surfactants. Further, the results of field tests of SP and ASP in the abovementioned countries were considered. In the discussion part, based on the considered results, the main issues and uncertainties were identified, based on which some recommendations were proposed for improving the process of preparation and injection of surfactants to increase oil recovery. In particular, we identified an area of additional laboratory and scientifically practical research. The outcomes of this work will provide a clearer picture of SP and ASP, as well as information about their limitations, current challenges, and potential paths forward for the development of these technologies from an economic and technological point of view. Full article
(This article belongs to the Special Issue The Optimization of Well Testing Operations for Oil and Gas Field)
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Review
Overview of Integrated Electric Motor Drives: Opportunities and Challenges
Energies 2022, 15(21), 8299; https://doi.org/10.3390/en15218299 - 07 Nov 2022
Viewed by 667
Abstract
Integrated Motor Drives (IMDs) have recently received extensive attention. In electric vehicles (EVs), electric propulsion aircraft, and ship propulsion systems, integrated motors have the great potential to replace traditional motors with the distinct merits of compact size, high power density, high efficiency, and [...] Read more.
Integrated Motor Drives (IMDs) have recently received extensive attention. In electric vehicles (EVs), electric propulsion aircraft, and ship propulsion systems, integrated motors have the great potential to replace traditional motors with the distinct merits of compact size, high power density, high efficiency, and high-cost effectiveness. This paper investigates and reviews integrated motor drives’ development and critical technologies. It not only reveals the research progress of the motor structure, converter, volume optimization, heat dissipation design, and weakening electromagnetic interference of integrated motor drives but also explores in detail the applications of wide-bandgap semiconductors and the integration of LCL filters. In addition, this paper also puts forward the concept of integrated motor drive integration level and establishes a corresponding quantitative method to evaluate IMDs integration level. In the future, integrated wireless motor drives will have a broad scope of research and application. IMDs systems will play an important role in applications requiring high power density, providing solutions to motor system size and heat dissipation problems. This overview will help clarify the opportunities, challenges, and future development of IMDs. Full article
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Article
Improvements to and Experimental Validation of PI Controllers Using a Reference Bias Control Algorithm for Wind Turbines
Energies 2022, 15(21), 8298; https://doi.org/10.3390/en15218298 - 07 Nov 2022
Viewed by 451
Abstract
In this study, a reference bias control (RBC) algorithm for variable speed and variable pitch wind turbines was designed and validated. To improve the performance of conventional PI control algorithms, the RBC algorithm applies biased references to power and pitch angle to the [...] Read more.
In this study, a reference bias control (RBC) algorithm for variable speed and variable pitch wind turbines was designed and validated. To improve the performance of conventional PI control algorithms, the RBC algorithm applies biased references to power and pitch angle to the pitch and the torque control loops, respectively. To validate the control performance of the improved RBC algorithm, hardware in the loop simulator (HILS) was conducted using a commercial programmable logic controller (PLC). The performance of a conventional PI control algorithm and the proposed RBC algorithm were compared for the target wind turbine model in terms of both the transition region and the rated power region. In the transition region, the proposed RBC algorithm improved the sudden dips in the generator torque and power, which often occur when using a control algorithm with a switching logic. As a result, the damage equivalent load (DEL) of the main shaft was reduced by 15%. In the rated power region, the rotor speed deviation was reduced by 22% and the power deviation was reduced by 21%. To experimentally validate the control performance and applicability of the RBC algorithm, wind tunnel testing using a wind turbine scaled model was additionally performed. Similarly to the HILS testing result, it was confirmed that the DEL of the main shaft and fluctuation of the rotor speed and power decreased with the proposed RBC algorithm. Full article
(This article belongs to the Special Issue Advancement in Wind Turbine Technology)
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Review
Co-Torrefaction Progress of Biomass Residue/Waste Obtained for High-Value Bio-Solid Products
Energies 2022, 15(21), 8297; https://doi.org/10.3390/en15218297 - 07 Nov 2022
Viewed by 598
Abstract
The co-torrefaction of several biomasses may be a viable solution in the study area, as it produces biofuels and addresses waste-treatment concerns. This review evaluates biomass through ultimate, proximate, and FTIR analyses, and the mechanism of the co-torrefaction process is observed for product [...] Read more.
The co-torrefaction of several biomasses may be a viable solution in the study area, as it produces biofuels and addresses waste-treatment concerns. This review evaluates biomass through ultimate, proximate, and FTIR analyses, and the mechanism of the co-torrefaction process is observed for product quality with a synergistic effect. Furthermore, the parameters of co-torrefaction, including temperature, reaction time, mass yield, energy yield, and the composition of the H/C and O/C ratio of the co-torrefied materials, are similar to those for coal composition. Different reactor types, such as fixed-bed, fluidized-bed, microwave, and batch reactors, are used for co-torrefaction, in which biomass blends with optimized blend ratios. The co-torrefaction process increases the bio-solid yield and heating value, the capacity to adsorb carbon dioxide, and the renewable fuel used for gasification. One of the objectives of this study is to adopt a process that must be viable, green, and sustainable without generating pollution. For this reason, microwave co-torrefaction (MCT) has been used in many recent studies to transform waste and biomass materials into an alternative fuel using a microwave reactor. Full article
(This article belongs to the Special Issue Comprehensive Utilization and Technology of Biomass)
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Review
A Review of Molten Salt Reactor Multi-Physics Coupling Models and Development Prospects
Energies 2022, 15(21), 8296; https://doi.org/10.3390/en15218296 - 06 Nov 2022
Viewed by 750
Abstract
Molten salt reactors (MSRs) are one type of GEN-IV advanced reactors that adopt melt mixtures of heavy metal elements and molten salt as both fuel and coolant. The liquid fuel allows MSRs to perform online refueling, reprocessing, and helium bubbling. The fuel utilization, [...] Read more.
Molten salt reactors (MSRs) are one type of GEN-IV advanced reactors that adopt melt mixtures of heavy metal elements and molten salt as both fuel and coolant. The liquid fuel allows MSRs to perform online refueling, reprocessing, and helium bubbling. The fuel utilization, safety, and economics can be enhanced, while some new physical mechanisms and phenomena emerge simultaneously, which would significantly complicate the numerical simulation of MSRs. The dual roles of molten fuel salt in the core lead to a tighter coupling of physical mechanisms since the released fission energy will be absorbed immediately by the molten salt itself and then transferred to the primary heat exchanger. The modeling of multi-physics coupling is regarded as one important aspect of MSR study, attracting growing attention worldwide. Up to now, great efforts have been made in the development of MSR multi-physics coupling models over the past 60 years, especially after 2000, when MSR was selected for one of the GEN-IV advanced reactors. In this paper, the development status of the MSR multi-physics coupling model is extensively reviewed in the light of coupling models of N-TH (neutronics and thermal hydraulics), N-TH-BN (neutronics, thermal hydraulics, and burnup) and N-TH-BN-G (neutronics, thermal hydraulics, burnup, and graphite deformation). The problems, challenges, and development trends are outlined to provide a basis for the future development of MSR multi-physics coupling models. Full article
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Article
Improved Locating Method for Local Defects in XLPE Cable Based on Broadband Impedance Spectrum
Energies 2022, 15(21), 8295; https://doi.org/10.3390/en15218295 - 06 Nov 2022
Viewed by 540
Abstract
The crosslinked polyethylene (XLPE) cable safety is affected by environmental factors and artificial defects during operation. This work proposes an improved locating method based on broadband impedance spectrum (BIS) to locate local defects in XLPE cables. The calculation process of the algorithm has [...] Read more.
The crosslinked polyethylene (XLPE) cable safety is affected by environmental factors and artificial defects during operation. This work proposes an improved locating method based on broadband impedance spectrum (BIS) to locate local defects in XLPE cables. The calculation process of the algorithm has been analyzed. The selection of the incident Gaussian signal and the peak recognition method have been discussed, where the pulse width of the Gaussian signal was found to be determined primarily by the upper limit frequency of the traveling wave transmitting in the cable. The centroid and function fitting methods were established to reduce the peak recognition error caused by the test sampling rate. This work verified the accuracy of the algorithm through experiments. A vector network analyzer (VNA) was used to test the BIS of the cable. A 20 m-long cable containing abrasion and an inserted nail with different depths was measured in the BIS test. It was found that the abrasion and the nail could be located. The locating deviation of abrasion was within ±1%, and the centroid and function fitting methods could effectively reduce the locating deviation. The locating deviation was within ±1% when the depth of the nail inserted into the cable accounted for less than 50% of the insulation thickness. When the depth exceeded 75% of the insulation thickness, the deviation of each method was more significant, and the maximum absolute value of the deviation was 4%. Full article
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Article
OpΕnergy: An Intelligent System for Monitoring EU Energy Strategy Using EU Open Data
Energies 2022, 15(21), 8294; https://doi.org/10.3390/en15218294 - 06 Nov 2022
Viewed by 719
Abstract
In this paper, the basic structure of an ICT platform of energy indicators, Openergy, is analytically presented, leveraging energy open data to help address the energy crisis more democratically. More specifically, its applicability as a dynamic tool for the management of climate, environmental, [...] Read more.
In this paper, the basic structure of an ICT platform of energy indicators, Openergy, is analytically presented, leveraging energy open data to help address the energy crisis more democratically. More specifically, its applicability as a dynamic tool for the management of climate, environmental, and socioeconomic information is described, and its efficiency in helping uncover insights for optimal data-driven decisions is depicted. Openergy uses data from the official portal for European data and the Eurostat site. Its database consists of data related to six energy categories, EU 2020 energy targets, energy balance, electricity production, transport fuels, heat production, and gas emissions, and each one includes its own indicators for EU countries. The platform includes visualizations of these data as well as time series modeling and forecasting, and the results are depicted at Openergy platform. The time series modeling provides forecasts with confidence intervals of each indicator until 2020 in each energy category. Empirical validation, RMSE, and MAE values showed that in almost all cases and estimations, the predicted values are in very good agreement with the observed values. Full article
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