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The entropy change causing dipolar depolarization is proposed as an origin of electrical power generation in triboelectric generators using polar materials. Rubbing mechanically forces permanent dipoles in materials to become orientationally ordered, establishing a low entropy state with an initial dipolar polarization P 0. In this state, the electric field within the materials is zero, but a nonzero Helmholtz free energy F = F 0 = P 0 2 2 (C s − C ∞) arises from the entropy contribution (C s , static capacitance; C ∞ , capacitance at high frequency). Consequently, this state is energetically unstable and undergoes a spontaneous transition into a disordered high entropy state with F < F 0 , resulting in the establishment of a non-zero electric field. Through this process, the energy bounded in materials as the entropy component of free energy is converted, and the electrical energy becomes F 0 η with η = 1 − C ∞ C s (0 < η < 1). Electrical circuit analysis shows that this energy conversion process can be well represented by introducing a virtual resistance R p = τ C s − C ∞ (τ , dipolar relaxation time). This suggests that the entropy change in finite time τ serves as the origin of electrical power generators. Under the matching condition τ = C s R , the power spectrum at the load is best aligned with that at the generator, maximizing the power transmission. The results presented here serve as a basis for understanding the principle of electric power transmission in triboelectric generators through dipolar depolarization. [ABSTRACT FROM AUTHOR]

A new design of a flexible and compact electrostatic generator with dielectric fluid is presented in this work. The generator utilizes the flow of dielectric fluid between two dielectric films to change the capacitance and converts mechanical energy into electrical energy. We fabricate a dielectric fluid generator (DFG) and build up an experimental setup to investigate the performance of energy harvesting. We use an optimal triangular electromechanical cycle and achieve a maximum energy harvesting power of 1.83 mW with a device that the length of the longest side is 15 cm. The power density is 35.2 μW g−1, and the conversion efficiency is 17.8%. The parameters of the DFG, including the initial voltage, the applied force, and the mechanical loading time, are studied. As a demonstration, we use the DFG to harvest electrical energy from hand tapping to power LEDs. The DFG is flexible and compact, which is promising for harvesting energy from human movements. [ABSTRACT FROM AUTHOR]

The direct conversion of thermal energy into electrical current via thermoelectric (TE) effects relies on the successful integration of efficient TE materials into thermoelectric generators (TEGs) with optimized characteristics to ensure either optimum output power density or conversion efficiency. Successfully employed for powering deep-space probes and extraterrestrial rovers since the 1960s, the development of this technology for waste-heat-harvesting applications faces several key issues related to the high temperatures and oxidizing conditions these devices are subjected to. This Perspective provides a brief overview of some prospective thermoelectric materials/technologies for use in radioisotope thermoelectric generators utilized in space missions and highlights the progress made in the field over the last years in the fabrication of TEGs. In particular, we emphasize recent developments that enable to achieve increased power densities, thereby opening up novel research directions for mid-range-temperature applications. In addition to showing how using lower quantities of TE materials may be achieved without sacrificing device performance, we provide an outlook of the challenges and open questions that remain to be addressed to make this technology economically and technologically viable in everyday-life environments. [ABSTRACT FROM AUTHOR]

To address the escalating demand for electrical energy, developing high-performance electrochemical energy storage materials is crucial. Metal oxides represent promising materials for high-energy-density supercapacitors. Among these materials, transition metal-based tungstates exhibit significantly enhanced electrical conductivity compared to pure oxides. However, their low inherent conductivity, restricted electrochemically active sites, significant volume expansion, lower capacity, and deprived cycling stability undermine their electrochemical properties. Herein, we synthesised an oxygen vacancy-enriched NiCoWO4 electrode by a simple solid-state, solvent-free grinding process using NaBH4. The Ov-NiCoWO4 electrode displays an impressive capacitance of 703.66 F g−1 at 1 A g−1 and exceptional cycling stability with 87% retention over 2000 cycles at 7 A g−1. This excellent performance is attributed to the oxygen vacancy in the Ov-NiCoWO4 material, which increases the electron carrier density, accelerates electron transportation, enhances the active surface area, and boosts the redox reactivity of the material. In the as-prepared real-life supercapacitor configuration of Ov-NiCoWO4//AC, a determined capacitance of 129.10 F g−1 at 1 A g−1 is achieved. Additionally, it exhibits an energy density of 37.699 W h kg−1 with a power density of 724.98 W kg−1, signifying exceptional performance. Furthermore, it maintains an impressive cycle life, retaining approximately 88.5% over 1000 cycles. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells (PCFCs), which are based on proton conducting electrolytes, are a class of power generation devices that can efficiently operate at the intermediate (500–700 °C), even low (450 °C) temperatures, but their development is hindered by sluggish cathodic kinetics at reduced temperatures. At the PCFC cathode, the absorbed oxygen molecules react with oxygen vacancies, protons and electrons to generate water and release electrical energy. Thus, the PCFC cathode materials require percolation network for proton, oxide-ion, and electron carriers simultaneously. In this work, we developed a triple ionic-electronic conductor BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ as a new cathode material for the PCFCs using BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ as the electrolyte. Anode supported cells were fabricated and the performances were investigated. Compared with the parent oxide, tungsten doping can significantly improve the electrochemical reduction kinetic of oxygen. The BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ based PCFC obtained the peak power density of 688 mW ⋅ cm−2 at 600 °C, which is 1.29 time higher than that of BaCo 0.4 Fe 0.4 Zr 0.2 O 3-δ based PCFC (the peak power density of 534 mW ⋅ cm−2 at 600 °C). Moreover, BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ has a better thermal expansion matching with the electrolyte material BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ. [Display omitted] [ABSTRACT FROM AUTHOR]

Solid oxide cells (SOCs) hold considerable promise as devices for efficient, reversible conversion between chemical and electrical energy, facilitating a global shift toward renewable energy. Electrode performance is critical for SOC efficiency and durability and composite materials are key to developing high‐performance electrode catalysts. However, conventional mechanical mixing and infiltration methods often lead to large particle sizes, uneven distribution, and weak interfacial interactions, thus limiting electrochemical activity and longevity. Recent advancements have produced powerful new strategies for creating composite materials. These include metal exsolution and oxide segregation for fuel electrodes and one‐pot synthesis, segregation, phase reaction, and dynamic cation exchange for air electrodes. These techniques yield highly active, uniform nano‐catalysts and robust multi–phase interfacial contacts, significantly improving electrochemical activity and durability. This work reviews these advanced strategies and their applications in SOCs. It provides valuable insights for designing and optimizing SOC catalyst materials, accelerating the development of this vital energy conversion technology. [ABSTRACT FROM AUTHOR]

Compared to traditional resources, user-side resources are of various types and have more significant uncertainty about their regulatory capacity, leading to difficulties in coordinating decisions about their simultaneous participation in the electric energy and peaking ancillary services markets. This paper proposes a joint bidding decision-making method for the day-ahead electricity energy and peak shaving auxiliary service market based on distributed robust opportunity constraints, which addresses the problem of difficulty in using an accurate probability density distribution to represent the uncertainty process of user-side resources. Firstly, a data-driven method for characterizing the uncertainty of load regulation capacity is investigated, and fuzzy sets are constructed without assuming specific probability distributions of random variables. Then, to minimize the risk expectation of the joint bidding cost on the customer side, a bidding strategy that considers the uncertainty is proposed. Finally, an example simulation verifies the reasonableness and effectiveness of the proposed joint bidding method, and the results show that the constructed model overcomes the problem of over-conservatism of the robust model, and the computational adaptability is better than that of the stochastic model, which achieves a better balance between robustness and economy. [ABSTRACT FROM AUTHOR]

This study investigates the visible light‐assisted photocatalytic degradation of rhodamine B (Rh B) dye using MoS2–CdS nanocomposite. Two crucial operational parameters, illumination time and the weight ratio of MoS2 to CdS, are systematically examined. Approximately, 91.9% of Rh B solution with a concentration of 10 mg/L is degraded by the MoS2–CdS photocatalyst under 60 min of illumination, with a photocatalyst dosage of 0.5 g/L. The results are consistent with a pseudo‐first‐order kinetic model, wherein the degradation rate constant of CdS increases fourfold after amalgamation with MoS2. The formation of the composite with MoS2 results in 1.72 times increase in the apparent quantum yield and 3.15 times decrease in the electrical energy consumption per order of CdS nanorods under similar experimental conditions. The investigation also comprehensively explores the reactive species responsible for Rh B degradation under visible light in the presence of MoS2–CdS photocatalyst. This analysis confirms that both hydroxyl and superoxide anion radicals play a dominant role in Rh B degradation. These findings underscore the potential practical applications of MoS2–CdS nanorods in eco‐friendly water treatment technologies, offering efficient and sustainable solutions to contemporary environmental challenges. [ABSTRACT FROM AUTHOR]

To alleviate resource shortage and environmental pollution, solar energy can be converted into thermal energy stored in phase change materials and in turn generate electrical energy. To enhance the solar energy utilization efficiency of solar‐thermal‐electrical conversion devices and prevent the heat loss to the environment at night, an intelligent solar‐responsive phase‐change system is innovatively designed consisting of a graphene aerogel film/paraffin wax stamen with an ultra‐high thermal conductivity of 46.7 W m−1 K−1, and thermally preserving aerogel film/liquid crystal elastomer bilayer petals that can bend solar‐responsively by the synergistic effect of solar‐thermal energy conversion and heat‐induced contraction. The solar‐responsive phase‐change system achieves daytime blooming for solar‐thermal conversion with simultaneous energy storage and nighttime closing for minimizing heat loss to the environment, exhibiting a high solar‐thermal conversion and energy storage efficiency of 89.4% and delaying its temperature drop by the thermal preservation effect of the petals. The assembled solar‐responsive solar‐thermal‐electric generator can reach an output voltage of 1033.8 mV at a light intensity of 500 mW cm−2 and continue to generate electrical energy during nighttime, holding tremendous promise in efficient solar energy conversion, storage, and utilization. [ABSTRACT FROM AUTHOR]

The direct liquid fuel cell (DLFC) constitutes a promising energy conversion system that directly conveys the chemical energy of liquid fuels into electrical energy. In certain DLFCs, gas is produced as a product of electrochemical reactions during operation. However, the accumulation of gas inside the porous electrode can significantly hinder the transport of reactants, leading to the failure of active sites and severe concentration loss. To address this issue, a gradient‐ordered membrane electrode assembly (MEA) is designed and fabricated, consisting of a dual‐gradient diffusion layer that comprises a pore‐size gradient and a wettability gradient as well as a catalyst layer constructed by nanoneedle catalyst. This MEA promptly removes the produced gas and delivers the fresh solution, thereby enhancing the cell power output and stability. The fuel cell with the gradient‐ordered MEA achieves a remarkable peak power density of 177 mW cm−2 and a discharging time of 19 h, which are more than four times and 30 times, respectively, higher than those of the conventional MEA. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) offers a novel approach for converting high‐entropy mechanical energy into electrical energy, yet achieving high charge density remains critical. Optimizations using dielectrics with high specific capacitance have mitigated air breakdown, but charge loss within dielectrics persists as a limiting factor. Here, based on poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF‐TrFE‐CFE)) with high specific capacitance, (P(VDF‐TrFE‐CFE)) composites’ trap density and energy are engineered using high‐polarity interfaces from barium titanate (BTO) nanoparticles and dense chain segment stacking induced by electrostatic interaction with polyetherimide (PEI) to enhance charge retention capability. With modified high interfacial traps, an ultrahigh charge density of 9.23 mC m−2 is achieved in external charge excitation (ECE) TENG using 0.2 vol% PEI/P(VDF‐TrFE‐CFE) film, marking the highest charge density reported for single‐unit TENGs. This work provides novel material strategies for high‐performance TENGs, paving the way for their large‐scale practical applications. [ABSTRACT FROM AUTHOR]

Direct current (DC) motors are crucial in drones, robotics, and electrical devices. Conventionally, the DC motor is driven by a switching electricity converter, which utilizes electrical energy to drive mechanical motion. However, the rapid on-off switching actions in the switching electricity converter would cause electromagnetic interference (EMI), impairing the functionality of drive systems. Here, we propose a photon-driven DC motor system based on photonic converter, which utilizes optical energy to drive mechanical motion, and therefore avoids EMI derived from electrical switching and immunizes against EMI during electrical energy transmission in conventional switching electricity-driven DC motor system. The operation principle and power modulation-based speed control are also presented for the proposed photon-driven DC motor system. The experiments demonstrate that the motor accurately follows the speed reference and withstands load disturbances. This innovation opens new potential for DC motor applications by improving electromagnetic compatibility. The researchers showcase a photon-driven DC motor system, that utilizes optical energy to drive mechanical motion, avoids EMI derived from electrical switching action and immunizes against EMI in conventional electricity-driven DC motor systems [ABSTRACT FROM AUTHOR]

In the transition from traditional electrical energy generation with mainly linear sources to increasing inverter-based distributed generation, electrical power systems' power quality requires new monitoring methods. Integrating a high penetration of distributed generation, which is typically located in medium- or low-voltage grids, shifts the monitoring tasks from the transmission to distribution layers. Compared to high-voltage grids, distribution grids feature a higher level of complexity. Monitoring all relevant nodes is operationally infeasible and costly. State estimation methods provide knowledge about unmeasured locations by learning a physical system's non-linear relationships. This article examines a new flexible, close-to-real-time concept of harmonic state estimation using synchronized measurements processed in a neural network. A physics-aware approach enhances a data-driven model, taking into account the structure of the electrical network. An OpenDSS simulation generates data for model training and validation. Different load profiles for both training and testing were utilized to increase the variance in the data. The results of the presented concept demonstrate high accuracy compared to other methods for harmonic orders 1 to 20. [ABSTRACT FROM AUTHOR]

Air cathode microbial fuel cell (MFC) can use the biological activities of microorganisms to convert organic matter into ideal electrical energy, but this efficiency has not been satisfactory. The air cathode requires an optimal catalyst to enhance the power output of the MFC by improving its low oxygen reduction reaction (ORR) activity. Micro Cu-doped Co3O4 nano-flower-like catalyst is successfully synthesized in this study using a metal-organic framework as the precursor material. The addition of 5% Cu induces a higher concentration of oxygen vacancies, thereby optimizing the local electronic state of the active site and enhancing the catalytic performance for oxygen reduction in the 5% Cu-Co3O4 material. Consequently, when equipped with this material, the power output of the air cathode MFC is approximately 2.85 times greater than that achieved with pure Co3O4. This provides a novel design idea for the application of nano-flower-like transition metal oxygen reduction catalysts in MFC. [ABSTRACT FROM AUTHOR]

Today, energy harvesting has developed into a technique from which various aspects are still hidden. By extracting energies from the environment and even the human body, and converting them into electrical energy, we can supply power to low‐consumption electronic devices. Energy harvesting works by inhibiting small amounts of ambient energies; otherwise, it is wasted in other forms such as heat, vibration, and light. In this paper, we aim to eliminate or minimize the dependence of portable electronic devices to the batteries, which have limited life times, service costs, handling, and environmental problems. This is accomplished via incorporating the hybrid energy‐harvesting techniques and designed to power (bio)medical devices in order to measure vital signs. In this circuit, by simultaneously harvesting RF, light, thermal, and solar (natural and artificial) energies, we were able to increase the reliability of continuous supply of electrical energy in energy‐harvesting systems by generating and storing maximum power from the environment. Supercapacitors are used as the energy storage elements so that there is no energy waste, and each system is constantly storing the electrical energy with the aid of a diode block. In addition, with the help of supercapacitors, this device is able to transmit a maximum of 420 mW to the load and the total efficiency is equal to 74%. [ABSTRACT FROM AUTHOR]

Barium titanate doped with calcium and zirconium (BCZT) relaxor ferroelectric ceramics enhance energy storage capabilities due to their excellent ferroelectric and dielectric properties. In this investigation, BCZT particles (Ps) were incorporated into poly (vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) using the solvent casting method to prepare biocompatible composite films with varying BCZT Ps contents. The uniform dispersion and distribution of BCZT Ps throughout the polymer matrix results in robust interfacial interactions, promoting improved nucleation of the β-phase in PVDF-HFP and increased thermal stability with higher BCZT Ps loading. The Young's modulus and tensile strength of the composites experienced respective increases of 78.2 % and 41.8 % with the addition of 20 wt% BCZT Ps. While the dielectric constant was improved from 12 to 31. This research contributes to the development of flexible composite films with different BCZT Ps contents, to promote an innovative and environmentally friendly energy harvesting technology. This innovation captures environmental vibrations and converts them into electrical energy to supply a variety of sensors. [ABSTRACT FROM AUTHOR]

The paper presents the planning (sizing) of a hybrid islanded system containing only renewable sources including wind turbines, photovoltaics, and bio‐waste energy units for the simultaneous supply of electrical and thermal energy. The mentioned renewable sources are used to supply electrical energy. The bio‐waste unit (BEU) is equipped with combined electrical and thermal technology. It is used along with heat pumps to supply thermal energy. Electrical and thermal storage are employed to make the renewable power output as close as possible to the demand level. Electric storage can be either stationary (e.g., battery) or mobile (e.g., electric vehicles), but thermal storage is as stationary type of storage. In the following, the proposed scheme minimizes construction and maintenance costs imposed by power sources, storage devices, and power electronic converters, and expected storage degradation cost. This plan is bound to the model of operation of sources, storage devices, and power electronic converters. In this model, renewables are the main source of power to supply consumers, where storage is adopted to increase the generation level to make it as close as possible to the demand curve. The uncertain parameters are imposed by the load, renewable phenomena, and mobile storage parameters. To model these uncertainties, stochastic optimization based on unscented transformation is used. Finally, the findings of the paper demonstrate that the suggested scheme succeeds in the economic planning of the system with a simultaneous supply of electrical and thermal energy. The BEU equipped with a combined electricity and heat system along with thermal storage and a heat pump to supply thermal load besides providing electric energy can reduce the planning cost by 2.9% compared with the case with only electrical energy. Also, the mobile storage presence in the hybrid system can reduce the number of stationary storage devices, which alone results in a 7.7% decrease in the planning cost of the hybrid system. [ABSTRACT FROM AUTHOR]

Introduction. To enhance the quality of power and ensure a consistent electricity supply, this study proposes the utilization of a unified power quality conditioner (UPQC) system integrated with solar photovoltaic (PV) technology. The innovation involves single DC-link connecting back-to-back voltage-compensating components arranged in series and shunt, forming the PV-UPQC. The shunt compensator utilizes energy from a PV array to address harmonics in the load current. The objective is to mitigate voltage dips and spikes by injecting voltage that is either in phase with or out of phase with the common coupling point through a series compensator. The method combines the benefits of generating renewable energy to enhance electrical quality. The goal of the paper is the power quality enhancement of grid-integrated solar PV system. The novelty of the proposed work consists of enhancement of grid-integrated solar PV system with UPQC. The purpose of integrating a UPQC into a grid-connected solar PV system is to enhance power quality by mitigating issues such as voltage fluctuations, harmonics and reactive power imbalance. Methods. The proposed topology is implemented in MATLAB/Simulink with grid-integrated solar PV system with UPQC. Results. Integrating UPQC with a grid-connected solar PV system yields substantial improvements in power quality. This includes effectively mitigating voltage fluctuations and harmonics, resulting in smoother operation and reduced disturbances on the grid. Practical value. The proposed topology has proven to be extremely useful for grid-integrated solar PV system with UPQC applications. [ABSTRACT FROM AUTHOR]

Thermally chargeable supercapacitors can collect low‐grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics. However, the low Seebeck coefficient and heat‐to‐electricity conversion efficiency hinder further application. In this paper, we designed a high‐performance thermally chargeable supercapacitor device composed of ZnMn2O4@Ti3C2Tx MXene composites (ZMO@Ti3C2Tx MXene) electrode and UIO‐66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro‐propylene ionogel electrolyte, which realized the thermoelectric conversion and electrical energy storage at the same time. This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K−1, thermal voltage of 243 mV, and outstanding heat‐to‐electricity conversion efficiency of up to 6.48% at the temperature difference of 4.4 K. In addition, this device showed excellent charge–discharge cycling stability at high‐temperature differences (3 K) and low‐temperature differences (1 K), respectively. Connecting two thermally chargeable supercapacitor units in series, the generated output voltage of 500 mV further confirmed the stability of devices. When a single device was worn on the arm, a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics. [ABSTRACT FROM AUTHOR]

A triboelectric nanogenerator (TENG) working on a contact electrification and electrostatic induction principle is a promising energy source for fulfilling the energy demand of low power electronic devices by converting the ambient mechanical energy to useful electrical energy. Here, a polymer nanocomposite film-based triboelectric nanogenerator has been designed by embedding reduced graphene oxide (rGO) nanosheets in a polyvinylidene fluoride (PVDF) matrix as one of the friction layers. The PVDF nanocomposite film-based TENG was constructed and examined for structural, electrical, and surface properties with varied weight percentages of rGO nanofillers (0.0 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%). The experimental results demonstrate that the addition of rGO in a PVDF matrix considerably increased the output performance of the TENG device. The TENG device with 1.5 wt% of rGO can deliver the maximum output voltage and current of 95.9 V, and 16.8 μA, respectively, which are ~ 3 and ~ 7 times the voltage and current produced by pristine PVDF film-based TENG. The enhanced performance of the nanogenerator is attributed to the addition of conductive nanofillers in the polymer matrix which improves the surface charge density of polymer nanocomposite films by forming a conduction network, resulting in more effective charge transfer. Moreover, the output of the nanogenerator is stored in the capacitor and used to drive commercial LEDs, revealing the TENGs' potential applications for designing self-powered electronic devices. [ABSTRACT FROM AUTHOR]

A popular class of efficient energy harvesting technologies is the triboelectric nanogenerator (TENG). There has been considerable research demonstrating the feasibility of converting mechanical motions into electrical energy by using these devices. In the design of TENGs, the power generated and its optimization are the most important aspects. However, not all factors affecting TENG performance are well understood. The main criteria for choosing materials is surface charge density, flexibility, and mechanical resistance. In some types of TENGs that are time-varying capacitors, the dielectric constant of the material can be a significant factor affecting the performance of these nanogenerators. In this research, using simulation, we investigate the effect of increasing the dielectric constant on the performance of the TENG in the contact-separation model (CSTENG). We find that increasing the dielectric constant is very effective in thick structures; it boosts the charge transferred under short-circuit conditions (QSC), current, maximum power, and figure of merit. However, there is little effect of the dielectric constant on thin CSTENG performance. Hence, the high-K material utilization effect is relaxed by thin dielectric layers. We then analyze the conditions of frequency matching and we obtain the optimal condition to achieve maximum power. To achieve optimal power output, thin CSTENGs require materials with a low dielectric constant. In contrast, thick structures can be optimized by utilizing high-K materials. Based on these findings, design rules for TENGs can be derived. [ABSTRACT FROM AUTHOR]

In this study, a broadband polarization and angle‐independent metamaterial absorber (MA) is investigated in the microwave range. It is made up of a periodic array of multi‐layered metal‐dielectric stepped cones. Since the dimensions of the layers forming the unit cell are different, each layer resonates at different frequencies with overlapping bands. The overall response of the structure, with its extremely wide bandwidth, can be obtained by summing all the overlapping frequency responses corresponding to each layer. In numerical simulation, it is observed that the absorption at normal incidence is above 90% in the frequency range between 9.68 and 17.45 GHz and 95% in the frequency range between 9.91 and 14.86 GHz. The energy harvesting ratios of the structure are also evaluated in a wide spectral band. A power ratio of around 90% is obtained in the same frequency range in accordance with absorption response. A noticeable harvesting efficiency of up to 82% is observed, which represents the energy level converted into electrical energy on resistors. [ABSTRACT FROM AUTHOR]

Green hydrogen production from water is one attractive route to non-fossil fuel and a potential source of clean energy. Hydrogen is not only a zero-carbon energy source but can also be utilized as an efficient storage of electrical energy generated through various other sources, such as wind and solar. Cost-effective and environmentally benign direct hydrogen production through neutral water (∼pH 7) reduction is particularly challenging due to the low concentration of protons. There is currently a major need for easy-to-prepare, robust, as well as active electrode materials. Herein we report three new molecular electrodes that were prepared by anchoring commercially available, and environmentally benign cobalt-containing electrocatalysts with three different ligand frameworks (porphyrin, phthalocyanine, and corrin) on a structurally modified graphite foil surface. Under the studied reaction conditions (over 7 h at 22°C), the electrode with Co-porphyrin is the most efficient for the water reduction with starting ∼740 mV onset potential (OP) (vs. RHE, current density 2.5 mA/cm2) and a Tafel slope (TS) of 103 mV/dec. It is followed by the molecular electrodes having Co-phthalocyanine [825 mV (OP), 138 mV/dec (TS)] and Vitamin-B12 (Co-corrin moiety) [830 mV (OP), 194 mv/dec (TS)]. A clear time-dependent improvement (>200 mV over 3 h) in the H2 production overpotential with the Co-porphyrin-containing cathode was observed. This is attributed to the activation due to water coordination to the Co-center. A long-term chronopotentiometric stability test shows a steady production of hydrogen from all three cathode surfaces throughout seven hours, confirmed using an H2 needle sensor. At a current density of 10 mA/cm2, the Co-porphyrin-containing electrode showed a TOF value of 0.45 s−1 at 870 mV vs. RHE, whereas the Co-phthalocyanine and Vitamin-B12-containing electrodes showed 0.37 and 0.4 s−1 at 1.22 V and 1.15 V (vs. RHE), respectively. [ABSTRACT FROM AUTHOR]

Bacterial cellulose is a biodegradable and ecologically safe material that has the potential to convert mechanical vibrations into electrical energy. This review introduces green energy harvesting, a novel concept that harnesses natural processes to provide sustainable energy. A thorough overview of bacterial cellulose, covering its distinctive features, its biological origin, and its energy conversion process, is fully presented. The different materials and methods used to design and fabricate bacterial cellulose‐based energy harvesters are explored. Moreover, the various applications and benefits of these devices in the context of renewable energy are examined. The current challenges and limitations of this emerging field are identified and the possible avenues for future research are suggested. The significance of adopting eco‐friendly approaches in achieving a balance between human needs and environmental preservation is highlighted. By providing a comprehensive and critical assessment of bacterial cellulose as a green energy harvester, this review aims to motivate researchers, engineers, and policymakers to tap into the rhythmic potential of this natural material in building a more sustainable and resilient future. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) provide promising power supply solutions by transforming mechanical energy into electrical energy. However, enhancing electrical performance of TENGs is essential for their widespread practical applications and commercialization. In this study, we fabricated TENGs in vertical contact‐separation mode using a tribopositive material—polyvinyl alcohol (PVA) slime—which is biocompatible, flexible, and wearable, decorated with graphene nanoplatelets (GnPs), and paired with tribonegative silicone. We analyzed the correlation between the electrical performance of the TENGs and the inherent triboelectric properties of the constituent material, including the evaluation of surface roughness, the measurement of the contact potential difference (CPD), and the material's dielectric constant. The incorporation of GnPs increased the dielectric constant of the composite material and its electron‐donating tendency, thus, increasing the contact potential difference. The GnPs concentration of 1 wt% was identified as the optimal value, resulting in a 42% increase in power density. The 1 wt% GnPs@PVA&Silicone TENG exhibited an open‐circuit voltage of 718 V and a peak power density of 15.3 W/m2. This study sheds light on enhancing the energy harvesting efficiency of TENGs through the utilization of biocompatible tribopositive and tribonegative materials. [ABSTRACT FROM AUTHOR]

The introduction of porosity into ferroelectric ceramics can decrease the effective permittivity, thereby enhancing the open circuit voltage and electrical energy generated by the direct piezoelectric effect. However, the decrease in the longitudinal piezoelectric coefficient (d33) with increasing porosity levels currently limiting the range of pore fractions that can be employed. By introducing aligned lamellar pores into (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3, this paper demonstrates an unusual 22–41% enhancement in the d33 compared to its dense counterpart. This unique combination of high d33 and a low permittivity leads to a significantly improved voltage coefficient (g33), energy harvesting figure of merit (FoM33) and electromechanical coupling coefficient (k332$k_{33}^2$). The underlying mechanism for the improved properties is demonstrated to be a synergy between the low defect concentration and high internal polarizing field within the porous lamellar structure. This work provides insights into the design of porous ferroelectrics for applications related to sensors, energy harvesters, and actuators. [ABSTRACT FROM AUTHOR]

Reversible protonic ceramic electrochemical cell (R-PCEC) is a new energy conversion device that can achieve efficient conversion between chemical energy and electrical energy. However, the oxygen electrode has poor activity towards oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which hinders the large-scale application of R-PCEC. Therefore, in order to improve the catalytic activity of oxygen electrodes, La 0.5 Sr 0.5 Co 0.2 Fe 0.8 O 3 (LSCF) is prepared using mesoporous silica SiO 2 (SBA-15) and polymethyl methacrylate (PMMA) as templates, and it was combined with BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY) to form a composite oxygen electrode for R-PCEC. Compared to the LSCF with solid-state reaction method, LSCF with hard-template method shows higher specific surface area and more oxygen vacancy, resulting in excellent ORR catalytic activity. In addition, LSCF prepared using PMMA as a template exhibits the best ORR catalytic activity, and the single cell with this composite oxygen electrode shows the highest maximum power density of 406 mW cm−2 in fuel cell (FC) mode with wet H 2 (3%H 2 O) and air as the fuel and oxidant, respectively. Additionally, it demonstrates a current density of −973 mA cm−2 at 1.3 V in electrolysis cell (EC) mode with wet air (10%H 2 O) as the oxidant. The single cell also shows good reversibility in FC mode and EC mode. This work provides a new strategy to improve the bifunctional activity of oxygen electrode in R-PCEC. [ABSTRACT FROM AUTHOR]

Although 3D micropattern has received considerable attention due to their remarkable usability, the introduction of specific functions, such as “chromism”, is still a challenge mainly due to the lack of adequate functional materials that can be introduced into 3D printing system. In this study, 3D micropatterns with temperature‐responsive properties are created by elaborately aligned thermochromic polymer microfibers using charge reversal electro‐jet writing (CREW) method with a 3D printer. A reversible color change in response to the temperature change is exhibited in the micropattern, displaying various chromic colors, such as red, blue, and black, at their own thermochromic temperatures. Multiple‐color phases can be sequentially expressed in a single structure by incorporating pigments of different colors with distinguishable color shift ranges. Various patterning methods are proposed for manufacturing diverse patterns and demonstrating applications using combinations of color. In addition to directly increasing temperature, the thermochromic process of micropatterns can be induced by heat generated from external factors using electrical energy. These 3D thermochromic micropatterns using the CREW method can be extended to various fields, including sensors, clothing, and anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

The introduction of porosity into ferroelectric ceramics can decrease the effective permittivity, thereby enhancing the open circuit voltage and electrical energy generated by the direct piezoelectric effect. However, the decrease in the longitudinal piezoelectric coefficient (d33) with increasing porosity levels currently limiting the range of pore fractions that can be employed. By introducing aligned lamellar pores into (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3, this paper demonstrates an unusual 22–41% enhancement in the d33 compared to its dense counterpart. This unique combination of high d33 and a low permittivity leads to a significantly improved voltage coefficient (g33), energy harvesting figure of merit (FoM33) and electromechanical coupling coefficient (k332$k_{33}^2$). The underlying mechanism for the improved properties is demonstrated to be a synergy between the low defect concentration and high internal polarizing field within the porous lamellar structure. This work provides insights into the design of porous ferroelectrics for applications related to sensors, energy harvesters, and actuators. [ABSTRACT FROM AUTHOR]

Highlights: Recent advancement in solution-processed thin film transparent photovoltaics (TPVs) is summarized, including perovskites, organics, and colloidal quantum dots. Pros and cons of the emerging TPVs are analyzed according to the materials characteristics and the application requirements on the aesthetics and energy generation. Promising TPV applications are discussed with emphasis on agrivoltaics, smart windows and facades. Electrical energy is essential for modern society to sustain economic growths. The soaring demand for the electrical energy, together with an awareness of the environmental impact of fossil fuels, has been driving a shift towards the utilization of solar energy. However, traditional solar energy solutions often require extensive spaces for a panel installation, limiting their practicality in a dense urban environment. To overcome the spatial constraint, researchers have developed transparent photovoltaics (TPV), enabling windows and facades in vehicles and buildings to generate electric energy. Current TPV advancements are focused on improving both transparency and power output to rival commercially available silicon solar panels. In this review, we first briefly introduce wavelength- and non-wavelength-selective strategies to achieve transparency. Figures of merit and theoretical limits of TPVs are discussed to comprehensively understand the status of current TPV technology. Then we highlight recent progress in different types of TPVs, with a particular focus on solution-processed thin-film photovoltaics (PVs), including colloidal quantum dot PVs, metal halide perovskite PVs and organic PVs. The applications of TPVs are also reviewed, with emphasis on agrivoltaics, smart windows and facades. Finally, current challenges and future opportunities in TPV research are pointed out. [ABSTRACT FROM AUTHOR]

Exploration for sustainable energy resources is essential to minimize the dependence on fossil fuels and to improve environmental parameters. Here, the possibility of utilizing bio‐waste‐derived electrolytes as an electrical energy resource by placing them across semipermeable membranes prepared through parallel stacking of coir fibers is examined. The nanofluidic membrane (d‐CF‐V) prepared by modifying the inner walls of the bio‐fluidic channels with atomically thin layers of vanadium pentoxide (VO) shows excellent perm‐selectivity (t+ = 0.87, with 1000‐fold concentration difference) and electricity conversion efficiency (≈ 28.2%). With simulated sea and river water, the d‐CF‐V yields output energy up to 2.4 W m−2, similarly with mineral acid bases (0.5 m HCl and 0.01 m NaOH), the d‐CF‐V shows an energy output of 11.8 W m−2. The sun‐dried Garcinia morella (Kuji thekera), and charred peels of Musa balbisiana (banana) are used as sustainable sources of bio‐electrolytes, which in combination with permselective d‐CF‐V yielded a power density of ≈1.4 W m−2. By replacing standard Ag/AgCl electrodes with nanomaterials exhibiting contrasting charge transfer activities, oxidized carbon nanotube membrane (o‐CNT) and polyaniline (PANI) membrane the output voltage is enhanced from –127 to –568 mV and current output is increased from 10.2 to 51.5 µA. [ABSTRACT FROM AUTHOR]

Kinetic energy harvesting has significant potential, but current methods, such as friction and deformation-based systems, require high-frequency inputs and highly durable materials. We report an electrochemical system using a two-phase immiscible liquid electrolyte and Prussian blue analogue electrodes for harvesting low-frequency kinetic energy. This system converts translational kinetic energy from the displacement of electrodes between electrolyte phases into electrical energy, achieving a peak power of 6.4 ± 0.08 μW cm−2, with a peak voltage of 96 mV and peak current density of 183 μA cm−2 using a 300 Ω load. This load is several thousand times smaller than those typically employed in conventional methods. The charge density reaches 2.73 mC cm−2, while the energy density is 116 μJ cm−2 during a harvesting cycle. Also, the system provides a continuous current flow of approximately 5 μA cm−2 at 0.005 Hz for 23 cycles without performance decay. The driving force behind voltage generation is the difference in solvation Gibbs free energy between the two electrolyte phases. Additionally, we demonstrate the system's functionality in a microfluidic harvester, generating a maximum power density of 200 nW cm−2 by converting the kinetic energy to propel the electrolyte through the microfluidic channel into electricity. Kinetic energy harvesting often requires high-frequency inputs and durable materials. Here, the authors present an electrochemical system using immiscible liquid electrolytes and Prussian blue analogue electrodes to harvest low-frequency kinetic energy in a microfluidic device. [ABSTRACT FROM AUTHOR]

In order to produce reliable and reproducible ignition of lean fuel–air mixtures and highly stratified mixtures, it is necessary to ensure a high concentration of spark discharge energy and to provide a strong energy impulse for the triggering of chain processes of chemical decomposition of fuel molecules. For this reason, studies have been undertaken on the flow of electrical energy from the ignition system to the spark plug and on the formation of an electric discharge arc with a high concentration of thermal energy. The experimental results were obtained using an ignition coil energy test stand and a constant volume chamber with high-speed spark discharge recording capability. It was confirmed that increasing the charging time of the ignition coil from 0.5 ms to 5.0 ms increases the energy delivered to the coil from 9.5 mJ to 330 mJ. In the same range, the energy generated by the coil was recorded to range from 4.2 mJ to 70 mJ. The coil's efficiency was found to decrease with increasing charging time from 45% up to 20.5%. Further energy losses were presented when the spark discharge energy was analyzed. In the paper, the results of investigations concerning electric discharge arc development have been presented, illustrated by a few exemplary photos, and discussed. The mathematical interpretation of the electrical energy flux in the ignition system resulting from the energy of the discharge arc has been conducted and illustrated by some functional independences and relationships. [ABSTRACT FROM AUTHOR]

This study proposes a two-level optimization scheduling method for multi-region integrated energy systems (IESs) that considers dynamic time intervals within the day, addressing the diverse energy characteristics of electricity, heat, and cooling. The day-ahead scheduling aims to minimize daily operating costs by optimally regulating controllable elements. For intra-day scheduling, a predictive control-based dynamic rolling optimization model is utilized, with the upper-level model handling slower thermal energy fluctuations and the lower-level model managing faster electrical energy fluctuations. Building on the day-ahead plan, different time intervals are used for fast and slow layers. The slow layer establishes a decision index for command cycle intervals, dynamically adjusting based on ultra-short-term forecasts and incremental balance corrections. Case studies demonstrate that this method effectively leverages energy network characteristics, optimizes scheduling intervals, reduces adjustment costs, and enhances system performance, achieving coordinated operation of the IES network and multi-energy equipment. [ABSTRACT FROM AUTHOR]

Currently, a large amount of pharmaceutical waste (PW) and its derivatives are being produced and, in some cases, inadequate management or treatment practices are applied. In this regard, this research explores the adoption of several alternatives to deal with these problems, including biocarbon within the framework of the circular economy. Photocatalytic nanomaterials have been also extensively discussed as a feasible way to remove pharmaceutical compounds in wastewater. Although there are existing reports in this area, this document provides a detailed study of the synthesis process, experimental conditions, the integration of photocatalysts, and their impact on enhancing photocatalytic efficiency. Additionally, the low cost and ease of fabrication of lab-scale microbial fuel cells (MFCs) are thoroughly examined. This innovative technology not only facilitates the degradation of hazardous compounds in wastewater but also harnesses their energy to generate electricity simultaneously. The aforementioned approaches are covered and discussed in detail by documenting interesting recently published research and case studies worldwide. Furthermore, this research is of significant importance because it addresses the valorization of PW by generating valuable by-products, such as H2 and O2, which can occur simultaneously during the photodegradation process, contributing to more sustainable industrial practices and clean energy technologies. [ABSTRACT FROM AUTHOR]

With advances in technology, the generation of electrical energy through the harvesting of energies dissipated in the form of mechanical vibration, known as power harvesting, has received increasing attention in recent decades. It is undoubtedly an interesting means to power systems with low energy consumption. This research aims to evaluate an energy generation system based on the piezoelectric effect activated by mechanical excitation and develop a system capable of powering devices and sensors for temperature monitoring in a practical situation, such as in an engine room, aiming to ensure its safe operation. Two transducers subjected to vibrational excitation were evaluated, and then an energy generation system using a buck DC-DC converter circuit was assessed. The transducer was connected to the input of the board, the microcontroller to the output, and the LM35 temperature sensor along with the battery was used to ensure the circuit's autonomy. Additionally, the Attiny85 microcontroller was programmed to perform temperature monitoring tasks in a continuous low-energy-consumption mode. The obtained spectral analysis results showed a maximum generation power of 8.88 mW for the PZT-5H transducer and 3.3 mW for the P5-13B transducer. The use of LTC3588-1 increased the autonomy of the monitoring system by 64.3% and reduced the system's usage time in cases of temperature anomalies by 50%. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) use the metabolic actions of microorganisms in an anode chamber to convert the chemical energy from wastewater into electrical energy. To improve the MFC power generation performance and chemical oxygen demand (COD) removal efficiency, Stenotrophomonas acidaminiphila was added to the anode chamber of a dual-compartment MFC. In this process, Stenotrophomonas acidaminiphila promotes the degradation of macromolecules such as bis(2-ethylhexyl) phthalate in food waste oil. Additionally, the generated electrical energy reduced Cu2+ in the copper-containing wastewater in the cathode chamber to Cu monomers. The maximum power density of the MFC was 49.5 ± 3.5 mW/m2, the maximum removal efficiencies of COD and Cu2+ were 63.5 ± 5.8% and 96.5 ± 1.0%, respectively, and Cu2+ was reduced to brick-red Cu monomers. This study provides insights into the simultaneous implementation of food waste oil treatment and metal resource recovery. [ABSTRACT FROM AUTHOR]

This paper presents the energy performance simulation and monitoring of a solar powered house designed, built, and operated under Dubai's hot and humid climate, stressing the balance between the electricity consumption and the production of the roof PV system. The study shows a summary of the design process aimed at optimizing the house's energy performance and maximizing the direct use of solar energy in the specific UAE climatic scenario, which implies a consistent use of cooling throughout the year. The simulated and monitored data collected by a third-party organization grants the reliability of the analysis on the real case study. The comparison of the predicted and monitored PV production shows a moderate gap, primarily due to the variable climatic conditions, but ultimately confirms the efficiency and feasibility of the system. [ABSTRACT FROM AUTHOR]

Modern power industry widely uses high-voltage overhead lines to transport electrical energy, with these lines encountering the problems of corona discharge and leakage currents, especially under the conditions of rain and snowfall. One of the approaches to solving these problems is the creation of protective coatings that can diminish corona discharge under adverse weather conditions. This paper reports the results of studying a hydrophilic organosilicon coating based on aminopropyltriethoxysilane and poly(ethylene glycol) for aluminum wires. The study of the coating resistance to a long-term contact with water, UV radiation, and ozone-saturated atmosphere has shown that the hydrophilicity of the coating increases under the influence of these factors, thus improving its anticorona properties. Thus, the durability of the developed coating under the operating conditions opens prospects for its use in the power engineering. [ABSTRACT FROM AUTHOR]

Recently, systems for simultaneously producing electrical and thermal energy have been examined to boost efficiency and use energy resources most. By using the simultaneous production systems of electric and heat energy, achieving a high efficiency of 70% is possible based on the actual rates. Establishing the ideal functioning point of cogeneration systems is challenging due to variations in electrical and thermal loads and electrical energy tariffs at various times of the day and night. The expenses of installing and dismantling the system have not been considered in this field of study, which mostly focuses on systems without thermal energy storage tanks. As a result, in this research, the optimal operating point of a system made up of several independent units with the ability to buy and sell electrical energy was determined using a genetic algorithm based on the consumption of different fuels and the use of a thermal energy storage tank. Optimal design of combined cooling, heating and power generation systems is presented in this paper. The goal of this study is comparison of a new operational strategy for optimization of simultaneous production with conventional system in different seasons including hot, cold and moderate times. The accuracy of the modeling was also done in comparison to other references. Because of the grid's high rate of electrical energy, the modeling results demonstrate that during mild and summer seasons, the cogeneration system can completely satisfy all electrical and thermal demands in 13 to 22 h. For practically all Seasons, the cogeneration system's 24-h total cost is 50% cheaper than the traditional production method. It has also been shown that using an absorption chiller has balanced the electrical-to-thermal load ratio, boosted the cogeneration system's efficiency relative to its pre-absorption chiller condition, and lowered thermal energy loss. Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 5 Given name: [Fatemeh Razi] Last name [Astaraei]. Yes, author 5 name is "Fatemeh" and last name is "Razi Astaraei". Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [specify authors given name] Last name [specify authors last name]. Also, kindly confirm the details in the metadata are correct.Yes. [ABSTRACT FROM AUTHOR]

To analyze the impact of electrical system thermal management on cruise performance and the selection of performance parameters under different operating conditions for the tilt-wing eVTOL, a tilt-wing eVTOL cruise simulation model is established by using the aircraft cruising speed as the control variable, the cruising time and electrical energy consumption as the objective functions, based on the 2D dynamics, drag, energy consumption and electrical system thermal management calculation model of the aircraft. Set different weights according to actual flight conditions,and optimize the solution based on the specific characteristics of the model using an improved particle swarm optimization algorithm. Taking the typical tilt-wing eVTOL aircraft Vahana as an example, performance parameters are obtained and compared. The simulation results show that the model has good optimization effects on reducing aircraft cruising time and reducing electrical energy consumption under various weight combinations. Compared to the most energy-efficient flight conditions, the fastest arrival can save about 50% of time but also consume 120% more electricity. Compared to the compromise of considering both time and energy consumption, the fastest arrival saves 20% of time while consuming 28% more electricity. [ABSTRACT FROM AUTHOR]

PMSM and AFPM are two different types of permanent magnet motors that convert electrical energy into mechanical energy and are used in many industrial applications. These motors are ahead of other motor types, especially in terms of energy efficiency and power density. In unmanned aerial vehicles, it is a great advantage to use a low weight and low volume propulsion provider. Moreover, the low level of acoustic noise is important for UAVs. In this paper, a new coreless AFPM (C-AFPM) was designed, and the prototype was carried out to achieve low acoustic noise. The acoustic performance of six-step and FOC commutation techniques was observed. As a result, it has been seen that an AFPM driven with the FOC control technique emits around 30% lower acoustic noise than the scenario driven by the six-step technique with the new C-AFPM machine for UAVs. [ABSTRACT FROM AUTHOR]

Power system engineers' intention is to produce power, transport it, and finally distribute it to customers under safe and reliable operating conditions to provide continuous and stable electrical energy. However, this goal is often hindered by unexpected faults that can lead to system breakdown. As a result, power system modeling is an effective technique which helps the analysis of power systems. Besides this technique, mathematical methods provide comprehensible information about the system's state. Furthermore, various studies have employed different techniques to detect electrical faults. In this paper, electrical faults are selected using a risk and impact approach, and fault characteristics are found using the Short-time Fourier transform. The case study is the Djibouti power network, and it is modeled with all real parameters using MATLAB-SIMULINK software. Following that, several fault scenarios were run, and the analysis was conducted using the proposed mathematical method. Ultimately, the simulation results indicate that the most critical faults are single-line-to-ground and double-line-to-ground. Hence, the extraction of signal features for these fault types is carried out. These faults have a high short circuit current, which can cause damage to the electrical network, and while clearing the fault, the oscillatory transient state appears with low-frequency components. These frequency components significantly affect power quality, thereby reducing the system's performance. [ABSTRACT FROM AUTHOR]

Most electrical energy generation systems are based on synchronous generators; as a result, their analysis always provides interesting findings, especially if an approach different to those traditionally studied is used. Therefore, an approach involving the modeling and simulation of a synchronous generator connected to an infinite bus through a transmission line in a bond graph is proposed. The behavior of the synchronous generator is analyzed in four case studies of the transmission line: (1) a symmetrical transmission line, where the resistance and inductance of the three phases (a , b , c) are equal, which determine resistances and inductances in coordinates (d , q , 0) as individual decoupled elements; (2) a symmetrical transmission line for the resistances and for non-symmetrical inductances in coordinates (a , b , c) that result in resistances that are individual decoupled elements and in a field of inductances in coordinates (d , q , 0) ; (3) a non-symmetrical transmission line for resistances and for symmetrical inductances in coordinates (a , b , c) that produce a field of resistances and inductances as individual elements decoupled in coordinates (d , q , 0) ; and (4) a non-symmetrical transmission line for resistances and inductances in coordinates (a , b , c) that determine resistances and inductance fields in coordinates (d , q , 0) . A junction structure based on a bond graph model that allows for obtaining the mathematical model of this electrical system is proposed. Due to the characteristics of a bond graph, model reduction can be carried out directly and easily. Therefore, reduced bond graph models for the four transmission line case studies are proposed, where the transmission line is seen as if it were inside the synchronous generator. In order to demonstrate that the models obtained are correct, simulation results using the 20-Sim software are shown. The simulation results determine that for a symmetrical transmission line, currents in the generator in the d and q axes are −25.87 A and 0.1168 A, while in the case of a non-symmetrical transmission line, these currents are −26.14 A and 0.0211 A, showing that for these current magnitudes, the generator is little affected due to the parameters of the generator and the line. However, for a high degree of non-symmetry of the resistances in phases a, b and c, it causes the generator to reach an unstable condition, which is shown in the last simulation of the paper. [ABSTRACT FROM AUTHOR]

Actuators based on moisture-sorption-responsive materials can convert moisture energy into mechanical/electrical energy, making the development of moisture-sorption materials a promising pathway for harnessing green energy to address the ongoing global energy crisis. The deformability of these materials plays a crucial role in the overall energy conversion performance, where moisture sorption capacity determines the energy density. Efforts to boost the moisture absorption capacity and rate have led to the development of a variety of moisture-responsive materials in recent years. These materials interact with water molecules in different manners and have shown diverse application scenarios. Here, in this review, we summarize the recent progress on moisture-sorption-responsive materials and their applications. We begin by categorizing moisture-sorption materials—biomaterials, polymers, nanomaterials, and crystalline materials—according to their interaction modes with water. We then review the correlation between moisture-sorption and energy harvesting performance. Afterwards, we provide examples of the typical applications using these moisture-sorption materials. Finally, we explore future research directions aimed at developing next-generation high-performance moisture-sorption materials with higher water uptake, tunable water affinity, and faster water absorption. [ABSTRACT FROM AUTHOR]

This work is devoted to the investigation of dielectric permittivity which is influenced by electronic, ionic, and dipolar polarization mechanisms, contributing to the material's capacity to store electrical energy. In this study, an extended dataset of 86 polymers was analyzed, and two quantitative structure–property relationship (QSPR) models were developed to predict dielectric permittivity. From an initial set of 1273 descriptors, the most relevant ones were selected using a genetic algorithm, and machine learning models were built using the Gradient Boosting Regressor (GBR). In contrast to Multiple Linear Regression (MLR)- and Partial Least Squares (PLS)-based models, the gradient boosting models excel in handling nonlinear relationships and multicollinearity, iteratively optimizing decision trees to improve accuracy without overfitting. The developed GBR models showed high R2 coefficients of 0.938 and 0.822, for the training and test sets, respectively. An Accumulated Local Effect (ALE) technique was applied to assess the relationship between the selected descriptors—eight for the GB_A model and six for the GB_B model, and their impact on target property. ALE analysis revealed that descriptors such as TDB09m had a strong positive effect on permittivity, while MLOGP2 showed a negative effect. These results highlight the effectiveness of the GBR approach in predicting the dielectric properties of polymers, offering improved accuracy and interpretability. [ABSTRACT FROM AUTHOR]

The necessity to change systems generating electrical energy is evident. The best solution would be to use installations utilizing renewable energy sources, complemented by efficient electric energy storage. This process requires time and further development, as well as new achievements in this area. Improving the situation can also result from enhancing the efficiency of devices already in operation. For a coal-fired power block, an important aspect is the variability of loads and ensuring the highest efficiency of all devices that make up the technological chain of such a unit, especially in variable working conditions. The article presents a new solution for regulating the working parameters of a radial fan for use in power engineering, which has high efficiency over a wide range of loads. The proposed six-blade solution allows one to obtain 115 Pa higher total pressure compared to four-blade systems, and efficiencies higher by 4.6 percentage points. The process of selecting elements and design parameters of the fan and its control system is discussed. The performance characteristics of the device with the new control system are presented. [ABSTRACT FROM AUTHOR]

This article applies the exergy analysis to the production and use of sugarcane, considering a model published in the literature. In this way, we compute incident solar irradiation, carbohydrate production, water consumption, and the production of stalks and straws. Following the production estimate, we analyze a biorefinery production cycle, from solar irradiation to the biorefinery products on an exergy basis, from birth to production of sugar, electrical energy, and ethanol. The calculated sugarcane production values are 80.7 tons per hectare for a 52-week cycle. As a result, the average exergy efficiency of sugarcane is 4.99%, reaching peaks of 8.3%. When considering only the useful exergy generated in the production of stalks and straw, an annual yield of 17.86 kWh/m2 represents an overall exergy efficiency of 1.31%. Considering the energy conversion processes in the biorefinery, the exergy efficiency from the radiation to the products from the biorefinery was 0.38%. The photovoltaic modules already have a well-established application in the country, though they need to increase their insertion over time, whereby the panels exhibit an average exergy efficiency of 31.6%, resulting in an annual electrical energy production of 255.84 kWh/m2. The results show that photovoltaic modules are a more efficient alternative than sugarcane regarding exergy land use. In conclusion, this study briefly discusses the use of sugarcane and photovoltaic modules in the context of Brazil's energy transition towards a reduced dependence on fossil fuels, based on the fact that sugarcane already has a low carbon footprint for transportation using ethanol, with supply from more than 40,000 stations, and a similar or lower carbon footprint than electrical vehicles used across the country. [ABSTRACT FROM AUTHOR]

To ensure the constant availability of electrical energy, power companies must consistently maintain a balance between supply and demand. However, electrical load is influenced by a variety of factors, necessitating the development of robust forecasting models. This study seeks to enhance electricity load forecasting by proposing a hybrid model that combines Sorted Coefficient Wavelet Decomposition with Long Short-Term Memory (LSTM) networks. This approach offers significant advantages in reducing algorithmic complexity and effectively processing patterns within the same class of data. Various models, including Stacked LSTM, Bidirectional Long Short-Term Memory (BiLSTM), Convolutional Neural Network—Long Short-Term Memory (CNN-LSTM), and Convolutional Long Short-Term Memory (ConvLSTM), were compared and optimized using grid search with cross-validation on consumption data from Lome, a city in Togo. The results indicate that the ConvLSTM model outperforms its counterparts based on Mean Absolute Percentage Error (MAPE), Root Mean Squared Error (RMSE), and correlation coefficient (R2) metrics. The ConvLSTM model was further refined using wavelet decomposition with coefficient sorting, resulting in the WT+ConvLSTM model. This proposed approach significantly narrows the gap between actual and predicted loads, reducing discrepancies from 10–50 MW to 0.5–3 MW. In comparison, the WT+ConvLSTM model surpasses Autoregressive Integrated Moving Average (ARIMA) models and Multilayer Perceptron (MLP) type artificial neural networks, achieving a MAPE of 0.485%, an RMSE of 0.61 MW, and an R2 of 0.99. This approach demonstrates substantial robustness in electricity load forecasting, aiding stakeholders in the energy sector to make more informed decisions. [ABSTRACT FROM AUTHOR]

The article presents concepts and experimental studies for an energy harvester designed to convert short, pulsating, turbulent airflows into electrical energy. Such flows occur in the vicinity of roads, highways, and railway tracks, among other places, and are caused by passing vehicles. A laboratory prototype is built in the form of a pendulum deflected from an equilibrium position by the airflow. The pendulum's oscillations are converted into electrical energy using an electrodynamic transducer. The harvester uses a magnetic system that increases the frequency of the oscillations and increases the energy efficiency of the system. The harvester can be used to power local low-power electrical devices, such as highway monitoring systems. It is possible to place a set of multiple harvesters in the vicinity of the road, creating a visual effect of reeds waving in the wind. [ABSTRACT FROM AUTHOR]