Electrical Energy Research Articles

Piezoelectric Enhancement in P(VDF-TrFE) Copolymer Films via Controlled and Template-Induced Epitaxy.

The surge in wearable electronics and Internet of Things technologies necessitates the development of both flexible sensors and a sustainable, efficient, and compact power source. The latter further challenges conventional batteries due to environmental pollution and compatibility issues. Addressing this gap, piezoelectric energy harvesters emerge as one kind of promising alternative to convert mechanical energy from ambient sources to electrical energy to charge those low-energy-consumption electronic devices. Despite slightly lower piezoelectric performance compared with those inorganic materials, piezoelectric polymers, notably poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFE), offer compelling properties for both flexible mechanical energy harvesting and self-powered strain/stress sensing, though their piezoelectric performance is expected to be further enhanced via varieties of modulation strategies of microstructures. Herein, we reported the controlled epitaxy process of micrometer-thick copolymer films with the cooperation of friction-transferred poly(tetrafluoroethylene) templates and precise modulation of the annealing conditions. Epitaxial P(VDF-TrFE) films present averaged d33 piezoelectric coefficient of -58.2 pC/N between 50 Hz and 1 kHz with good electromechanical and thermal stability. Owing to the nature of anisotropic crystallization, the epitaxial films exhibit an anisotropic transverse piezoelectric property. Epitaxial films were further utilized for mechanical energy harvesting and monitoring of human pulsation and respiration. This study provided a feasible route for the development of high-performance flexible piezoelectric devices to meet the requirement of flexible electronics.

Optimal design of PV-SMES systems for power quality enhancement using pelicon optimized multi-level inverter model

In this article, a superconducting magnetic energy storage (SMES) system is integrated with a photovoltaic (PV) renewable energy source. The integrated system can achieve power balancing with voltage stability, high power quality, and reliability. Here, a Bonobo Optimization Algorithm (BOA)-based MPPT control has been developed to get the most electrical energy out of the solar PV cells under fluctuating weather conditions, including temperature and irradiance. The output voltage is greatly increased with minimal switching complexity by using the Zeta DC-DC converter, which helps to meet the energy requirements of load applications. Then, the Total Harmonics Distortions (THD) has been decreased with lower switching stress, power loss, and voltage ripples at the load using the sophisticated and simple five-level MLI circuit model. In addition, the performance of MLI has been greatly improved by tuning the controlling gain parameters with the use of Pelicon Optimization (PO) technique. Moreover, the Shunt Active Power Filter (SAPF) is used in order to achieve the best power quality results with the reduced overall harmonic distortions. The performance and results of the suggested circuit model are validated in this study through a complete simulation analysis using a variety of assessment indicators.

Rational construction of noble-metal-free fuel cell-supercapacitor hybrid power source using polyaniline electrode as both anode and cathode

The integration of fuel cell device and supercapacitor device into a singular hybrid power source at the electrode level can make the best use of the advantages of each individual device and more importantly, eliminate the energy loss by virtue of the conversion of chemical energy to electric energy on electrocatalyst material and the storage of electric energy on energy storage material simultaneously. To avoid the use of noble metal electrocatalyst and exploit the dual electrocatalytic and capacitive function of polyaniline, a noble-metal-free fuel cell-supercapacitor hybrid power source employing polyaniline electrode as both anode and cathode is rationally constructed. Based on electrochemical in-situ Raman spectroscopy, this work proposes that the open circuit potential (OCP) of polyaniline electrode is a simple and quick indicator of the redox state of polyaniline. After carefully selecting the fuel and carbon-based support, it is found that the ascorbic acid fuel and the carbon fiber cloth supported polyaniline contributes to the lowest OCP threshold in the anode, and thus the fastest self-charge and largest stabilized open circuit voltage of hybrid power source. The hybrid power source can be self-charged to 0.32 V and yield a peak power density of 0.21 mW cm−2.

Energy transfer, conversion and mechanical regulation in graded piezoelectric semiconductor bipolar junction transistor

While the effective regulation of carrier redistribution in piezoelectric semiconductor devices by mechanical loads through piezoelectric polarized electric fields is well-studied, there is a scarcity of reported research on the influence of energy transfer and conversion characteristics in a non-thermal equilibrium state of these devices. This paper establishes a nonlinear multi-field coupling model for piezoelectric semiconductor graded bipolar junction transistor (PS-GBJT) and proposes a corresponding multi-gradient iterative algorithm. We regard the product of current and built-in electric field as the work done by electric field force on carriers. By incorporating the energy absorbed/released during carrier recombination/generation process, we observe that non-equilibrium carriers act as a medium that facilitates energy conversion between these two mechanisms. Additionally, the non-uniformly distributed doping extends the influence of space charge region throughout entire transistor. In terms of external input electrical energy, the emitter, base, and collector regions play roles of input energy, transfer energy, and output energy, respectively. The study concludes by demonstrating the regulation of energy transfer or conversion efficiency in emitter, base, and collector regions through mechanical loads, thereby altering the heating behavior of entire GBJT and reshaping its energy transfer path. This leads to the significant finding that distinct energy transfer paths fundamentally define the various operational states of GBJT. The novel insights gained from this research hold reference value for thermal design and energy management of electronic devices.

Assessing the drivers of energy supply and demand in Sub-Saharan Africa

Ensuring reliable and sustainable energy access in sub-Saharan Africa requires exploring alternatives to traditional biomass and fossil fuels, crucial for overcoming challenges related to limited electricity and clean cooking energy access. Within this background and to assess the factors affecting energy supply and energy consumption, the Logarithmic Mean Divisia Index (LMDI) was applied across 48 sub-Saharan countries and adapted to the regional context considering energy access indicators.Key results showed that economic activity significantly influences both supply and demand growth. However, this growth is restricted by outdated infrastructure, resulting in inefficiencies and increased conversion losses. Policymakers thus face a dual challenge of promoting economic growth while modernizing energy infrastructure to sustain development.Moreover, targeted policies are essential, particularly in energy-intensive in energy-intensive sectors like wholesale and retail, while advocating for a comprehensive approach in the residential sector. This approach involves socioeconomic considerations, energy access enhancement, and the promotion of energy-efficient and renewable technologies to meet rising demand amid population growth and evolving consumption patterns.Furthermore, the study underscores the importance of enhancing both energy access levels and energy efficiency in the residential sector. Unlike the industrial sector, energy intensity is crucial for improving efficiency without compromising the level of access. Enhancing energy efficiency can significantly reduce energy consumption in households, which is important given the high reliance on energy-intensive practices such as cooking with traditional biomass.

Comparative Energy and Economic Analysis of Dish Stirling Engine and National Grid Electricity for Residential Building in Mafraq, Jordan

Comparative Energy and Economic Analysis of Dish Stirling Engine and National Grid Electricity for Residential Building in Mafraq, Jordan

Energy, economic and environmental evaluation of the energy storage capabilities of artificial lakes based on pumped-hydro storage systems with a case study of Daghgoli artificial recreational lake

In the present study, Daghgoli artificial recreational lake has been investigated as an energy storage system. This lake with a capacity of 54,000 (m3) is located in the largest metropolis of northwestern Iran, above the Eynali Mountains, in the vicinity of the city. The elevation of this lake is about 450 (m) from the downstream lake with a capacity of 60,000 (m3). The energy storage capacity of the lake has been evaluated based on the pumped-hydro method. Then, the capacity of this large “battery” to store a part of the excess energy generated by the Tabriz thermal power plant has been evaluated. In addition to the technical evaluation, a full economic analysis as well as environmental investigation of application of the lake as an energy storage system has been conducted. The capacity that can be develop the existing small wind farm in the vicinity of the lake so that its generated energy can be fully stored by the energy storage system based on Daghgoli Lake has also been determined. Finally, the capacity of the photovoltaic solar power plant that can be established in the flat plain adjacent to the lake to store its generated electricity by the lake to be used at night or peak hours has been also evaluated. The results showed that using the presented energy storage plan, 74.7(MWh) of excess electrical energy generated by the thermal power plant can be stored daily. By releasing this energy during peak hours, 13.24 (MW) of electricity can be generated with an energy conversion efficiency about 71 %. At the same time, the emission of 8508 tons of carbon dioxide can be prevented during a year. The investment payback period of the project is estimated to be 4.7 years. By using the designed energy storage system, a wind farm consisting of 16 turbines with a capacity of 660 (kW) or a photovoltaic solar plant with a capacity of 9.34 (MW) can be created.

Electrochemical and structural performances of carbon and glass fiber-reinforced structural supercapacitor composite at elevated temperatures

The structural supercapacitor can store electrical energy and withstand structural loads while saving substantial weight in many structural applications. This study investigated the development of a structural supercapacitor with a fiber-reinforced polymer composite system and explored the operating temperature’s influence on its performance. The electrochemical and mechanical properties of structural supercapacitors beyond the ambient temperature have not yet been studied; hence, evaluating parameters such as specific capacitance, energy density, cycle life, and structural performance at elevated temperatures are highly desired. We have designed and manufactured single and parallelly connected multilayer structural supercapacitor composites in this research. Carbon fibers were used as a bifunctional component, acting both as a current collector while acting as a mechanical reinforcement. In addition, glass fibers were added as the separator which is also acting as an integral reinforcement. The electrochemical and mechanical behavior of structural supercapacitors at elevated temperatures up to 85 °C were experimentally investigated. The test results revealed that at room temperature, the developed double-cell structural supercapacitor, which demonstrated an area-specific capacitance of 1.16 mF cm−2 and energy density of 0.36 mWh cm−2 at 0.24 mA cm−2, which are comparable to current achievements in structural supercapacitor research. The structural supercapacitor’s tensile, flexural, and compression strengths were measured as 109.5 MPa, 47.0 MPa, and 50.4 MPa, respectively. The specific capacitance and energy density reached 2.58 mF cm−2 and 0.81 mWh cm−2, while tensile, flexural, and compression strengths were reduced to 70.9 MPa, 14.2 MPa, and 8.8 MPa, respectively, at 85 °C. These findings provide new comprehensive knowledge on structural supercapacitor devices suitable for applications operating within a temperature range from ambient conditions to 85 °C.

Thermorechargeable battery composed of mixed electrodes

A thermorechargeable battery (TB) can be charged by heating or cooling, and hence, converts thermal energy into electric energy. The manufacture of TB, however, requires adjustment of the cathode and anode potentials by pre-oxidation. Here, we demonstrated that application of mixed electrodes composed of reduced and oxidized compounds makes the adjustment process unnecessary. The TB made of mixed electrodes exhibited excellent thermal cycle stability of the thermal voltage VTB and discharge capacity QTB between 20 °C and 50 °C.

The Indirect Carbon Cost of E-Mobility for Select Countries Based on Grid Energy Mix Using Real-World Data

Electric vehicles are considered by many as an emission-free or low-emission solution to meet the challenge of sustainable transportation. However, the operational input, electrical energy, has an associated cost, greenhouse gasses, which results in indirect emissions. Given this knowledge, we pose the following question: “Are zero-emission transportation targets achievable given our current energy mix?” The objective of this article is to assess the impact of a grid’s energy mix on the indirect emissions of an electric vehicle. The study considers real-world data, vehicle usage data from an electric vehicle, and carbon intensity data for India, the USA, France, the Netherlands, Brazil, Germany, and Poland. Linear programming-based optimization is used to compute the best charging scenario for each of the given grids and, consequently, the indirect emissions are compared to those of a high-efficiency 1.5 L diesel internal combustion engine for the vehicle: a 2019 Renault Clio dCi 85. The results indicate that for grids with low renewable energy penetration, such as those of Poland and India (Maharashtra), an electric vehicle, even when optimally charged, can be classified as neither a low- nor zero-emission alternative to normal thermal vehicles. Also, for grids with elevated levels of variation in their carbon intensity, there is significant potential to reduce the carbon footprint related to charging an electric vehicle. This article provides a real-world perspective of how an electric vehicle performs in the face of different energy mixes and serves as a precursor to the development of robust indicators for determining the carbon reductions related to the e-mobility transition.

Annual and Seasonal Variation of the Ocean Thermal Resources off the Mexican Coast

A large amount of thermal energy is stored in the oceans between the tropics, available for conversion into electrical energy using OTEC technology. The aim of this study was to determine the annual and seasonal variability of the oceanic thermal resource in Mexico. Using the WOA18 database, we mapped surface temperature at a 10 m depth, deep cold water (<5 °C), vertical temperature difference (18 and 20 °C), and temperature anomalies. From the results, four areas were analyzed as being suitable for the installation of OTEC technology: Pacific (A), Los Cabos (B), Caribbean (C), and Gulf of Mexico (G). The optimal thermal resource (≥20 °C) was found between a 400 and 1000 m depth in all seasons in A and C, in spring, summer, and autumn in G, and only in summer and autumn in B. The suboptimal thermal resource (between 18 and 20 °C) was present between 400 and 800 m in all seasons in A, C, and G, and in summer and autumn in B. These results provide new information of utmost importance for future location and design considerations of OTEC plants on Mexican coasts, and the methodology can be used in other areas where there is a lack of field data and the development of OTEC technology is being considered.

Copper-Graphene Composite (CGC) Conductors: Synthesis, Microstructure, and Electrical Performance.

Improving the electrical performance of copper, the most widely used electrical conductor in the world is of vital importance to the progress of key technologies, including electric vehicles, portable devices, renewable energy, and power grids. Copper-graphene composite (CGC) stands out as the most promising candidate for high-performance electrical conductor applications. This can be attributed to the superior properties of graphene fillers embedded in CGC, including excellent electrical and thermal conductivity, corrosion resistance, and high mechanical strength. This review highlights the recent progress of CGC conductors, including their fabrication processes, electrical performances, mechanisms of copper-graphene interplay, and potential applications.

Enhanced Performance of Self-Powered Ga2O3/ZnO:V Heterojunction Solar-Blind Ultraviolet Photodetectors by Coupling Ferroelectricity and Piezoelectricity.

Ferroelectric materials have aroused increasing interest in the field of self-powered ultraviolet (UV) photodetectors (PDs) for their switchable spontaneous polarization. However, the utilization of ferroelectric materials to modulate the built-in electric field and energy band at the junction interface has rarely been investigated. Herein, we design and fabricate self-powered solar-blind UV PDs based on a Ga2O3/ZnO:V heterojunction. The performance of the Ga2O3/ZnO:V PD is significantly enhanced through the reasonable coupling of ferroelectricity and piezoelectricity within the ZnO:V film. The device at 260 nm exhibits excellent photoelectric properties with high peak responsivity of 64.5 mA/W, a specific detectivity of 3.8 × 1010 Jones, and a rise/decay time of 1.9/45.2 μs, together with reproducibility and stability. Systematical energy band diagram analysis reveals that the excellent performance of Ga2O3/ZnO:V PD can be attributed to the driving forces arising from the addition of the depolarization field and piezoelectric field, which increases the intensity of built-in electric field and promotes the separation and transport of photogenerated carriers at the heterojunction interface. The findings of our research provide a novel avenue and valuable guidance for the design of high-performance self-powered photodetectors.

Augmented Two-Stage Hierarchical Controller for Distributed Power Generation System Powered by Renewable Energy: Development and Performance Analysis

The sustainable development of an area is highly reliant on a reliable electrical energy supply. Microgrids are important in integrating distributed energy resources (DERs) using power electronic converters. However, microgrid control becomes challenging with the increasing number of distributed generators and loads. With the conventional droop control method, power contributions from DER converters cannot be accurately shared due to a mismatch of line impedances. In this paper, an augmented hierarchical control mechanism is proposed to solve the issues mentioned above. This hierarchical control mechanism consists of primary and secondary controllers. The primary stage utilized the droop controller to improve optimal power flow, mainly for the resistive network. The secondary stage is based on an improved methodology to compensate for the voltage and frequency variations during small and large signal disturbances. Moreover, the modelling and analysis for PMSG-based wind energy conversion systems are also presented. The response of the primary controller for active and reactive power sharing is investigated. The analysis emphasizes the demonstration of optimal power-sharing under normal and abnormal conditions for the considered load. Finally, the suggested robust controller’s performance is evaluated in a MATLAB environment, and simulation results show the proposed scheme’s superiority under different operating conditions. The frequency is stable at 50 Hz after a 50 KW load is added.

A hierarchical optimization approach to maximize hosting capacity for electric vehicles and renewable energy sources through demand response and transmission expansion planning

Within the scope of sustainable development, integrating electric vehicles (EVs) and renewable energy sources (RESs) into power grids offers a number of benefits. These include reducing greenhouse gas emissions, diversifying energy sources, and promoting the use of green energy. Although the literature on hosting capacity (HC) models has grown, there is still a noticeable gap in the discussion of models that successfully handle transmission expansion planning (TEP), demand response (DR), and HC objectives simultaneously. Combining TEP, DR, and HC objectives in one model optimizes resource use, enhances grid stability, supports renewable and EV integration, and aligns with regulatory and market demands, resulting in a more efficient, reliable, and sustainable power system. This research presents an innovative two-layer HC model, including considerations for TEP and DR. The model determines the highest degree of load shifting appropriate for incorporation into power networks in the first layer. Meanwhile, the second layer focuses on augmenting the RES and EVs’ hosting capability and modernizing the network infrastructure. System operators can choose the best scenario to increase the penetration level of EVs and RESs with the aid of the proposed model. The proposed model, which is formulated as a multi-objective mixed-integer nonlinear optimization problem, uses a hierarchical optimization technique to identify effective solutions by combining the particle swarm optimization algorithm and the crayfish optimizer. When compared to traditional methods, the results obtained from implementing the proposed hierarchical optimization algorithm on the Garver network and the IEEE 24-bus system indicated how effective it is at solving the presented HC model. The case studies demonstrated that integrating DR into the HC problem reduced peak load by 10.4–23.25%. The findings also highlighted that DR did not impact the total energy consumed by EVs throughout the day, but it did reshape the timing of EV charging, creating more opportunities for integration during periods of high demand. Implementing DR reduced the number of projects needed and, in some cases, led to cost savings of up to 12.3%.

Self-Organizing Sub-μm Surface Structures Stimulated by Microplasma Generated Reactive Species and Short-Pulsed Laser Irradiation.

Catalysts are critical components for chemical reactions in industrial applications. They are able to optimize selectivity, efficiency, and reaction rates, thus enabling more environmentally friendly processes. This work presents a novel approach to catalyst functionalization for the CO2 reduction reaction by combining the reactive species of an atmospheric pressure plasma jet with the electric fields and energy input of a laser. This leads to both a nanoscale structuring as well as a controllable chemical composition of the surface, which are important parameters for optimizing catalyst performance. The treatment is conducted on thin copper layers deposited by high power pulsed magnetron sputtering on silicon wafers. Because atomic oxygen plays a key role in oxidizing copper, two photon absorption fluorescence is used to investigate the atomic oxygen density in the interaction zone of the COST plasma jet and a copper surface. The used atmospheric pressure plasma jet provides an atomic oxygen density at the surface in a distance of 8 mm to the jet nozzle of approximately or a flux of . Pulsed laser-induced dewetting is used to form nanoparticles from the deposited copper layer to enhance catalytic performance. Varying the layer thickness allows control of the size of the particles. A gas flow directed on the sample during the combined treatment disturbs the particle formation. This can be prevented by increasing the laser energy to compensate for the cooling effect of the gas flow. Investigating the surface using X-ray photoemission spectroscopy reveals that the untreated copper layer surface consists mostly of metallic copper and Cu(I) oxide. Irradiating the sample only with the laser did not change the composition. The combination of plasma and laser treatment is able to produce Cu(II) species such as CuO, whose concentration increases with treatment time. The presented process allows the tuning of the ratio of C2O/CuO, which is an interesting parameter for further studies on copper catalyst performance.

Design and Realization of Visual and Contact-Type Fast Charging Power Source.

Charging power supplies with both fast and visualization functions have a wide range of applications in the information and new energy industries. In this paper, the visualized and contact-type fast charging power supply based on WO3 film and Zn sheet is presented, and the prototype devices are fabricated. Different with the charging method of conventional batteries, charging is achieved by a Zn sheet contacting with a WO3 film moistened with water, resulting in a rapid discoloration of WO3. Theoretical investigation indicates that the interaction between Zn sheet and water molecules is the primary cause of the color change in the WO3 film. The WO3 film completes the colouring state within 10 s in the presence of Zn sheet and water, and the open-circuit voltage of the device is 0.7 V, which can be used to drive various electronics by series-parallel connection. This research introduces a novel method to induce colouring of WO3 films and proposes a fast charging mode different from traditional power sources. It provides valuable insights for the future development of fast charging in the field of electrical energy.

A hybrid solar/biomass active indirect kiln dryer for timber in the Democratic Republic of Congo

This paper presents a small-scale pilot project in the Democratic Republic of Congo of a hybrid kiln dryer for sawn timber powered by solar and biomass energy. The chamber’s thermal insulation comprised layers of vetiver grass, wood and clay, 100% biodegradable. Sun collectors and a supplementary furnace-burning biomass from the nearby sawmill provided the heating energy, while photovoltaic panels supplied electric energy for ventilation and electric devices. The climate was controlled through actuators operated by an electronic system for industrial kiln dryers. Despite relatively high production costs, primarily due to the photovoltaic system, the kiln allowed for good use of local labour and materials. Preliminary tests indicated an improved drying potential of the kiln compared external conditions with a consequent lower drying time and final MC. Data emphasised the influence of thermal energy in the drying rate: the extra power given by the furnace increased the drying rate from 0.4 to 1.4% day−1. The cost of energy ($/kWh) was calculated as 0.009 for the furnace, 0.05 for the solar collector and 0.14 for the photovoltaic. The conversion efficiency of solar collector resulted to be 48% against 14% of photovoltaic.

Design and Realization of Visual and Contact-Type Fast Charging Power Source.

Charging power supplies with both fast and visualization functions have a wide range of applications in the information and new energy industries. In this paper, the visualized and contact-type fast charging power supply based on WO3 film and Zn sheet is presented, and the prototype devices are fabricated. Different with the charging method of conventional batteries, charging is achieved by a Zn sheet contacting with a WO3 film moistened with water, resulting in a rapid discoloration of WO3. Theoretical investigation indicates that the interaction between Zn sheet and water molecules is the primary cause of the color change in the WO3 film. The WO3 film completes the colouring state within 10 s in the presence of Zn sheet and water, and the open-circuit voltage of the device is 0.7 V, which can be used to drive various electronics by series-parallel connection. This research introduces a novel method to induce colouring of WO3 films and proposes a fast charging mode different from traditional power sources. It provides valuable insights for the future development of fast charging in the field of electrical energy.

Electromagnetic Interference Shielding and Joule Heating Properties of Flexible, Lightweight, and Hydrophobic MXene/Nickel-Coated Polyester Fabrics Manufactured by Dip-Dry Coating and Electroless Plating.

High-performance electromagnetic interference (EMI) shielding materials with high flexibility, low density, and hydrophobic surface are crucial for modern integrated electronics and telecommunication systems in advanced industries like aerospace, military, artificial intelligence, and wearable electronics. In this study, we present flexible and hydrophobic MXene/Ni-coated polyester (PET) fabrics featuring a double-layered structure, fabricated via a facile and scalable dip-dry coating process followed by electroless nickel plating. Increasing the dip-dry coating iterations up to 10 cycles boosts the MXene loading content (∼31 wt %) and electrical conductivity (∼86 S/cm) of MXene-coated PET fabrics, while maintaining constant porosity (∼95%). The addition of a Ni layer enhances hydrophobicity, achieving a high water contact angle of ∼114° compared to only MXene-coated PET fabrics (∼49°). Furthermore, the 30 μm thick MXene/Ni-coated PET fabric demonstrates superior electrical conductivity (∼113.8 S/cm) and EMI shielding effectiveness (∼35.7 dB at 8-12 GHz) compared to only MXene- or Ni-coated PET fabrics. The EMI shielding performance of the MXene/Ni-coated PET fabric remains more stable in an air environment than only MXene-coated fabrics due to the outer Ni layer with excellent hydrophobicity and oxidation stability. Additionally, the MXene/Ni-coated PET fabric exhibits impressive Joule heating performance, swiftly converting electrical energy into heat and reaching high steady-state temperatures (32-92 °C) at low applied voltages (0.5-1.5 V).