Abstract Hybrid supercapacitors with their improved performance in energy density without altering their power density have been in trend since recent years. The hybrid supercapacitor delivers higher specific capacitance in comparison to the existing electric double layer capacitor (EDLC) and pseudocapacitors. Generally, the asymmetric behavior of hybrid supercapacitors which is the combination of EDLC and pseudocapacitor acts as an enhancer in its respective capacitance values. This asymmetric approach marks a new beginning towards the much-needed pollution free, long lasting and proficient energy-storing performance. Corresponding to their utilization in hybrid electric vehicles and similar sort of power necessity based devices; the research in developing new advanced storage devices finds an enormous and vast future ahead. The most significant factor for the energy efficient applications demands a considerably higher ratio of surface to the volume by incorporation of new materials. This review article gives an overview of recent advances in the development of hybrid supercapacitors, storage mechanism, criteria of formation, components, different electrode and electrolyte materials, electrochemical profile assessment, design fabrication and their applications.
Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics with capabilities beyond existing technologies due to its large bandgap, controllable doping, and the availability of large diameter, relatively inexpensive substrates. These applications include power conditioning systems, including pulsed power for avionics and electric ships, solid-state drivers for heavy electric motors, and advanced power management and control electronics. Wide bandgap (WBG) power devices offer potential savings in both energy and cost. However, converters powered by WBG devices require innovation at all levels, entailing changes to system design, circuit architecture, qualification metrics, and even market models. The performance of high voltage rectifiers and enhancement-mode metal-oxide field effect transistors benefits from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. Reverse breakdown voltages of over 2 kV for β-Ga2O3 have been reported, either with or without edge termination and over 3 kV for a lateral field-plated Ga2O3 Schottky diode on sapphire. The metal-oxide-semiconductor field-effect transistors fabricated on Ga2O3 to date have predominantly been depletion (d-mode) devices, with a few demonstrations of enhancement (e-mode) operation. While these results are promising, what are the limitations of this technology and what needs to occur for it to play a role alongside the more mature SiC and GaN power device technologies? The low thermal conductivity might be mitigated by transferring devices to another substrate or thinning down the substrate and using a heatsink as well as top-side heat extraction. We give a perspective on the materials’ properties and physics of transport, thermal conduction, doping capabilities, and device design that summarizes the current limitations and future areas of development. A key requirement is continued interest from military electronics development agencies. The history of the power electronics device field has shown that new technologies appear roughly every 10-12 years, with a cycle of performance evolution and optimization. The older technologies, however, survive long into the marketplace, for various reasons. Ga2O3 may supplement SiC and GaN, but is not expected to replace them.
H. Jouhara, Alina Żabnieńska-Góra, N. Khordehgah
et al.
Abstract Nowadays humans are facing difficult issues, such as increasing power costs, environmental pollution and global warming. In order to reduce their consequences, scientists are concentrating on improving power generators focused on energy harvesting. Thermoelectric generators (TEGs) have demonstrated their capacity to transform thermal energy directly into electric power through the Seebeck effect. Due to the unique advantages they present, thermoelectric systems have emerged during the last decade as a promising alternative among other technologies for green power production. In this regard, thermoelectric device output prediction is important both for determining the future use of this new technology and for specifying the key design parameters of thermoelectric generators and systems. Moreover, TEGs are environmentally safe, work quietly as they do not include mechanical mechanisms or rotating elements and can be manufactured on a broad variety of substrates such as silicon, polymers and ceramics. In addition, TEGs are position-independent, have a long working life and are ideal for bulk and compact applications. Furthermore, Thermoelectric generators have been found as a viable solution for direct generation of electricity from waste heat in industrial processes. This paper presents in-depth analysis of TEGs, beginning with a comprehensive overview of their working principles such as the Seebeck effect, the Peltier effect, the Thomson effect and Joule heating with their applications, materials used, Figure of Merit, improvement techniques including different thermoelectric material arrangements and technologies used and substrate types. Moreover, performance simulation examples such as COMSOL Multiphysics and ANSYS-Computational Fluid Dynamics are investigated.
Abstract With building electric demand becoming increasingly dynamic, and a growing percentage of intermittent renewable power generation from solar photovoltaics and wind turbines, the power grid is facing increasing challenge to manage the real time balance between the supply and demand. With advancements in smart sensing and metering, smart appliances, electric vehicles, and energy storage technologies, demand side management of residential buildings can help the grid to improve stability by optimizing flexible loads. This paper reviews recent studies on residential building demand side management, with a focus on characterization and quantification of energy flexibility covering various types of flexible loads, metrics, methods, and applications. The reviewed studies showed four levels of applications: building level (45%), district or community level (29%), system level (19%), and building sector level (7%). Shifting loads is the dominant flexibility type in 60% of applications, followed by shedding (19%), generation (16%), and modulating (6%). Depending on the technology and application scope, flexible operations have a wide range of performance, with peak power reductions of 1%~65%, energy savings up to 60%, operational cost reduction of 1%~48%, and greenhouse gas emission reductions of up to29%. More than half (51%) of the studies employed control strategies to achieve flexibility; among those 72% used optimal controls, while 28% used rule-based controls. About 58% of the studies used mathematical formulation to quantify energy flexibility. Most studies were based on simulation, while less than 15% of the studies had measurements from experiments or field tests. The review reveals research opportunities to address significant gaps in the existing literature: (1) establishing a common definition and performance metrics for energy flexibility of buildings that are technology and application agnostic, (2) developing an ontology to standardize representation of flexibility resources for interoperability, (3) integrating occupant impacts into the quantification and optimization of energy flexibility, and (4) developing requirements and credits of energy flexibility in building energy codes and standards. Findings from the review can inform future research and development of energy flexible buildings which are essential to a reliable and resilient power grid.
It is an exciting time for power systems as there are many ground-breaking changes happening simultaneously. There is a global concensus in increasing the share of renewable energy-based generation in the overall mix, transitioning to a more environmental-friendly transportation with electric vehicles as well as liberalizing the electricity markets, much to the distaste of traditional utility companies. All of these changes are against the status quo and introduce new paradigms in the way the power systems operate. The generation penetrates distribution networks, renewables introduce intermittency, and liberalized markets need more competitive operation with the existing assets. All of these challenges require using some sort of storage device to develop viable power system operation solutions. There are different types of storage systems with different costs, operation characteristics, and potential applications. Understanding these is vital for the future design of power systems whether it be for short-term transient operation or long-term generation planning. In this paper, the state-of-the-art storage systems and their characteristics are thoroughly reviewed along with the cutting edge research prototypes. Based on their architectures, capacities, and operation characteristics, the potential application fields are identified. Finally, the research fields that are related to energy storage systems are studied with their impacts on the future of power systems.
Jenny Damcevska, Sima Dimitrijev, Daniel Haasmann
et al.
The need for efficient power-conversion systems in renewable energy, electric vehicles, and industrial power applications has motivated the development of wide-bandgap power semiconductor devices, such as the SiC Schottky diode. An important parameter that establishes the reliability of these high-power devices is their repetitive forward surge current, which ensures robust circuit designs that can withstand high current conditions without damage or failure. However, there is no consistent measurement method to determine this parameter for SiC Schottky diodes, and manufacturers that provide this parameter have no clear indication of the methodology used to obtain the presented value. In this work, we propose a measurement method and a user-focused criterion for the repetitive peak forward surge current, which also ensures the junction temperature does not exceed the maximum device rating. We demonstrate the need for this criterion by comparing measured surge-current performance of commercially available diodes with two different structures—merged PN Schottky diodes and homogenous Schottky-barrier diodes—designed with three different blocking voltages: 650 V, 1200 V, and 1700 V.
Filipe Menezes, Sérgio Cunha, William Assis
et al.
Electric energy storage systems have advanced significantly in recent years, driven by the growing expansion of renewable energy sources, the rise of electromobility, and other emerging configurations within the current electrical energy system. Among the various energy storage technologies, supercapacitors have gained considerable attention. Due to their ability to deliver large amounts of power over short periods, supercapacitors can be highly effective in hybrid storage systems, for example, enhancing overall system performance. Therefore, detailed studies on supercapacitors and their electrical circuit models have been developed with the aim of representing them as close as possible to actual physical behavior for numerous applications, such as in the context of Digital Twin (DT), an application that will support the monitoring of the operation and health of the supercapacitor throughout its useful life. The present work aims to estimate optimally some parameters of an electrical circuit model of a supercapacitor, in such a way as to obtain responses with very low errors and, thus, be able to use this computational electrical modeling for the development of a Digital Twin system. For the optimal adjustment of the electrical circuit model parameters, a Genetic Algorithm (GA) is used. The response of the electrical circuit, adjusted by the Genetic Algorithm (GA), is then compared to the response obtained through computer simulation of a supercapacitor using PSIM software, which is a software well validated in such studies. The results demonstrated strong alignment between the response using GA and the response using PSIM. Specifically, the charge and discharge curves of the supercapacitor, obtained through GA adjustment and PSIM simulation, were very similar, showing an error of just 2.2%. Thus, the supercapacitor model adjusted via GA demonstrates a good response to the physical phenomenon in question and can be used to develop a Digital Twin (DT) system, aiding in the operational and health monitoring of the supercapacitor.
ObjectivesUrban rivers and lakes often serve as carriers of sewage, with a large amount of sediment enriched with nitrogen and heavy metal elements. The combustion disposal method is clean, efficient, economical, and environmentally friendly. Studying the combustion kinetics of the sediment is crucial for its disposal and utilization.MethodsThe thermogravimetric analysis method is employed to compare and analyze the single combustion characteristics of the sediment in Dianchi Lake. In order to provide a reference for practical engineering applications, the sediment is co-combusted with coal at mixing ratios of 10%, 20%, and 30%. Using KAS, FWO, and Coats methods, 11 commonly used kinetic mechanism functions and solid-state reaction mechanism functions are selected to fit the activation energy and mechanism functions of each reaction stage.ResultsThe combustion of sediment is divided into four stages. Compared with sludge and coal slurry, it has a lower ignition temperature, making it easier to burn, but a higher burnout temperature, indicating differences in the overall combustion characteristics. When sediment is burned at different heating rates, lower heating rates are more conducive to combustion. Co-combusting sediment with coal shows a synergistic effect, and their interaction has a positive impact on the combustion characteristics. As the mixing ratio increases, the ignition performance improves. However, when the mixing ratio reaches 30%, the combustibility index significantly decreases, indicating that excessive mixing ratio is detrimental to improving the combustion performance of the fuel. The final fitting shows that the reaction mechanisms in the second and third stages of the combustion process are consistent, while the fourth stage is different.ConclusionsSediment can be used as a fuel, burning of sediment and coal can improve the ignition performance of coal and conducive to the stable combustion of coal, but the mixing ratio should not exceed 30%. The research results provide a reference for practical engineering applications.
Applications of electric power, Production of electric energy or power. Powerplants. Central stations
Abstract Over the years, wind energy technology has vividly made progress, as it is economical and cleaner against fossil‐fuel alternatives. With the rapid upsurge in turbine ratings up to the MW‐power generation level, an unceasing effort is crucial to increase the torque/power density and power factor of the wind‐powered machines. Amongst wind‐powered machines, the permanent magnet vernier machine (PMVM) is renowned for its high torque density. This paper discusses the detailed design flow of a novel contra‐rotating PMVM including sizing equation, geometric relationships, and FEA‐based electromagnetic performance analysis compared to the conventional PMVM. The proposed contra‐rotating PMVM is analysed with two different winding configurations that is, first with crossed‐toroidal and later with concentrated winding configuration, and a comprehensive comparative analysis is made between proposed and conventional PMVM topologies. The contra‐rotation of rotors provides more torque/power than the co‐rotation within the given machine's size. This comparative analysis provides noteworthy insights into the superior performance of the proposed contra‐rotating PMVM topologies regarding torque/power, power factor, and efficiency. A superior torque/power of value 538.23 Nm/1.6 kW is achieved in the case of the design with crossed‐toroidal winding configuration with an efficiency of 97.82% whereas, a high‐power factor of 0.98 with an efficiency of 91.36% is achieved in the case of the design with concentrated winding configuration.