Electrical Energy Research Articles

Accounting for power take-off efficiency in optimal velocity tracking control of wave energy converters

There has been much research into how Wave Energy Converters (WECs) can capture energy from the waves and convert it into kinetic energy in the mechanical system (mechanical energy). However, because WECs typically generate power at high force and with low speed, the conversion of the mechanical energy into electrical energy can be inefficient. If Power Take-Off (PTO) efficiency is not accounted for in controller design then the efficiency of the WEC from wave energy to electrical energy can be poor. In this work, an adaptation of Optimal Velocity Tracking (OVT) control is presented, termed OVT-E, that accounts for PTO efficiencies in the controller formulation such that it converts more energy from the waves to electricity than traditional OVT approaches, termed OVT-M. Results show that, for an example WEC and PTO system in a simulation environment, OVT-E produces more efficient electrical energy conversion than OVT-M with lower forces through the drive-train. OVT-E is also shown to convert more electrical energy than an adaptive linear damping method. The methodology for designing OVT-E could have further applications when coupled with other controller implementations or if used alongside machine-learning for control co-design purposes.

Chemo-elasto-electro free energy of non-uniform system in the diffuse interface context

In the present work, we propose an alternative approach for deriving the free energy formulation of a non-uniform system. Compared with the work of Cahn and Hilliard (1958 J.Chem. Phys.28258-67), our approach provides a more comprehensive explanation for the individual energy contribution in a non-uniform system, including entropy, interaction energy, and internal energy. By employing a fundamental mathematical calculus, we reformulate the local composition within the interface region. Utilizing the reformulated local composition as well as classic thermodynamic principles, we establish formal expressions for entropy, interaction energy, and the internal energy, which are functions of both composition and composition gradients. We obtain a comprehensive free energy expression for a non-uniform system by integrating these energy density formulations. The obtained free energy expression is consistent with the formula type of Cahn and Hilliard and prodives more deeper physical interpretation. Moreover, using the same approach, we derive formulations for elastic energy and electric potential energy in a non-uniform system. However, the proposed approach encounters a limitation in the special case of a non-uniform fluid contacting a solid substrate. Due to the significant difference in the length scales between the solid-fluid and fluid-fluid interfaces, the wall free energy formulation based on the aforementioned concept is unsuitable for this multi-scale system. To address this limitation, we reformulate the wall free energy as a function of the average composition over the solid-fluid interface. Additionally, the previous derivation relies on an artificial treatment of describing the composition variation across the interface by a smooth monotone function, while the true nature of this variation remains unclear. By utilizing the concept of average composition, we circumvent the open question of how the composition varies across the interface region. Our work provides a thorough understanding for the construction of free energy formulations for a non-uniform system in condensed matter physics.

Failure mechanism and thermal runaway behavior of lithium-ion battery induced by arc faults

As the widespread of lithium-ion battery systems such as electric vehicles and energy storage systems, the number of safety incidents due to electrical faults are increasing. Many accident reports have demonstrated that arc faults have become one of the main triggers of LIB system accidents, however, the related studies are inadequate. In this study, an arc imitation system is employed to investigate the influence of different arc energies on battery safety valve, as well as the electrochemical characteristics of faulty batteries. The results show that the minimum arc power to breach the safety valve ranges from 110 to 441 W. The maximum temperature rise rate on the battery surface can exceed 15 °C/s with arc power of around 1000 W. Further, the testing of in-situ and ex-situ indicate the faulty batteries undergo degradation and failure due to that moisture in the air enters the battery interior, resulting in increased internal resistance, loss of active materials and cyclable lithium. Finally, the faulty battery has no valve opening during thermal runaway, and the ignition time is four hundred seconds earlier than that of the normal battery, indicating more severe fire dangers. The results are valuable for safety design of battery systems in relation to arc faults, as well as the characteristic for fault detection and early warning.

Multi-objective optimal coordination of electric vehicle charging, power grid, energy storages and renewables

Considering that the grid connection of variable renewable energies (VREs) and the disorderly charging loads of large-scale electric vehicles (EVs) will adversely affect the power grid stability, the optimization strategy of EV charging and grid-connected scheduling are investigated, in which energy storage system is added to balance the demand and supply of the power grid. First of all, considering the profit of EV charging station, the charging cost of EV users and power loss, a multi-objective optimal scheduling model of EV charging, power grid, pumped hydro-storage (PHS) and wind farm is constructed, which is improved from the aspect of wind farm wake. Then, the multi-objective optimization algorithm based on genetic algorithm is used to solve the model to realize the optimal charging of EVs. Finally, the IEEE-13 power grid is used to verify the effectiveness of the proposed multi-objective optimal scheduling model. Combined with a specific example for simulation analysis, the results show that the model can achieve orderly charging of EVs, ensuring the safety of the power grid and promote the use of VREs. In addition, the optimization algorithm can further improve the profit, and reduce the charging cost and power loss.

Optimal Clean Energy Resource Allocation in Balanced and Unbalanced Operation of Sustainable Electrical Energy Distribution Networks

Optimal Clean Energy Resource Allocation in Balanced and Unbalanced Operation of Sustainable Electrical Energy Distribution Networks

Demonstration of a novel jaw crusher design at a lab scale

ABSTRACT A novel jaw crusher was designed, constructed and tested at a lab scale. Differences from a conventional jaw crusher include a swing plate that is supported at the outlet, rather than the inlet, wear plates with a corrugation pattern that are designed to break the ore in bending rather than compression, and a trapezoidal wear plate shape to allow for swelling of broken ore. The crusher was tested using an ore sample that was mainly composed of feldspar. The performance of the crusher was evaluated by measuring changes in the size distribution of the ore and the corresponding electrical energy consumed, as a function of ore feed rate. The results indicated that the crusher product size distribution was narrower than that of the feed and independent of ore feed rate, with relatively little generation of fines, demonstrating that the crusher performed as designed in terms of ore breakage mechanism. Though calculated breakage efficiencies suggest that the crusher may be more energy efficient than a conventional jaw crusher, the use of an undersized crusher motor and possible deficiencies in the design of the transmission mechanism, prevent any concrete conclusions from being drawn.

Broadband and high-efficiency acoustic energy harvesting with loudspeaker enhanced by sonic black hole

It is well-known that acoustic energy sources can be seen as a promising alternative energy resource by using acoustic energy harvester (AEH) which can transform sound energy into usable electrical power. However, the current AEHs have been restricted by their narrow bandwidths and low energy conversion efficiencies. In this study, a broadband and high efficient AEH is presented. The proposed AEH comprises an open-end sonic black hole (SBH) structure and an electrodynamic loudspeaker. The sound pressure is amplified through the open-end SBH structure, then the loudspeaker is used as electricity generator to convert acoustic energy into electric energy. The open-end SBH is a cylindrical tube with an array of regularly-spaced rigid-walled thin rings. The inner radii of the SBH rings are quadratically decreasing and the SBH effect can be obtained. The model for energy harvesting and sound absorption performance of the proposed AEH is then presented. Finally, the open-end SBH is fabricated by 3D printing apparatus. A prototype of the AEH is designed and tested by using an impedance tube. The energy conversion efficiency and absorption coefficient from calculation and experiment show a reasonable agreement. The proposed AEH can convert 11 % of total incident sound energy from 50 Hz to 800 Hz. The maximum energy conversion efficiency can achieve 65 % at 425 Hz under optimal resistance load. Furthermore, the broadband sound absorption can also be achieved by using the proposed AEH.

Anionic Solvation Transition at Low Temperatures for Reversible Anodes in Lithium-Oxygen Batteries.

Li-O2 batteries provide a novel technology for electric energy storage due to their high energy density. However, the strong solvent coordination with Li+ at low temperatures impacts their performance and triggers irreversible interfacial reactions on the Li anode. Herein, cyclopentyl methyl ether (CME) is incorporated in a dimethoxyethane (DME)-based electrolyte to realize an anionic solvation transition at low temperatures in Li-O2 batteries. CME featuring a single O coordination site substitutes highly solvating DME in the first solvation sheath, and it induces more anion coordination to Li+ across the room- and low-temperature ranges. The low residence time of CME (66 ps at 25 °C, 382 ps at -40 °C.) in the solvation structures leads to the fast exchange of coordinated CME molecules with Li+ in comparison with DME and facilitates Li+ desolvation at low temperatures. The simultaneously generated inorganic-rich solid electrolyte interphase promotes Li+ transport to improve Li deposition and suppress Li dendrite formation. These enable the Li-O2 battery to present a good cycling stability of 110 cycles with a fixed capacity of 1000 mA h g-1 at -40 °C. This work paves the way for designing novel electrolytes in low-temperature batteries.

Air conversion of pyrolysis products of hydrocarbon raw materials into synthesis gas (H2+CO) for the production of electrical energy using solid oxide fuel cells

The article discusses the technology of combined production of electrical and thermal energy using preliminary air conversion of the pyrolysis liquid of automobile tires into synthesis gas, with its subsequent supply to the battery of an electrochemical generator. The electrical power of the installation is 100 kW, the network heater is 126 kW. The main energy characteristics of the installation were determined using the methods of physicochemical modeling and compilation of energy balances. It has been shown that the specific consumption of pyrolysis liquid for the production of electrical energy is 108 g/kW∙h (169 g r.f./(kW∙h)), and the heat consumption is 30 kg/GJ (196 kg r.f./Gcal). The specific consumption of natural and conventional fuels is compared with the specific fuel consumption at power plants operating on hydrocarbon natural fuels. They are slightly inferior to them, with the exception of the specific electricity generation from external heat consumption. Fuel utilization rate 46.4%. Recommendations are given for the use of pyrolysis liquid to generate electrical and thermal energy using a high-temperature fuel cell based on SOFC.

Piezoelectric supercapacitors: current trends and future outlook

Abstract The present review analyses the research and development of piezoelectric supercapacitor (PSC)-based self-charging storage devices (SCSDs) over the last few years, with a bird’s-eye view of the prevailing trends and the outlook for the future. Piezoelectric materials, known for their ability to convert mechanical energy into electrical energy, have emerged as a key player in the development of next-generation supercapacitors with self-charging capability. The present review begins with elucidating the fundamental principles of piezoelectricity and piezoelectric generators vis-à-vis materials and properties as well as their integration into supercapacitor design. Advancements in fabrication techniques and the diversity of materials used have been discussed in detail with a focus on various characterization techniques. The review also addresses existing limitations, such as low energy transfer efficiency and material toxicity, as well as presenting strategies to overcome these hurdles and proposing avenues for future research and development.

Predicting Stock Prices in the Electric Vehicle and Technology Sectors Using Long Short-Term Memory Models

Forecasting stock prices is a complex task because of the volatility and intricate temporal dependencies present in financial markets. Long Short-Term Memory (LSTM) networks, known for their proficiency in handling extended time-series data, offer an effective solution to these challenges. This paper delves into the applications in LSTM networks to forecast stock prices for various companies in the electric vehicle and related sectors, specifically examining data from Tesla, BYD, Panasonic, and NVIDIA. The study assesses the predictive accuracy and performance of these models using RMSE, MSE, MAE, and R metrics. By comparing these metrics across different companies, the paper provides an in-depth analysis of LSTM networks' effectiveness in financial forecasting. The findings indicate that when LSTM networks are optimized through hyperparameter tuning and architectural adjustments, they can accurately identify patterns in stock price data, offering valuable insights for investors and analysts in the electric vehicle, technology, and energy industries.

Exploring the Potential of Solar Energy for Electricity and Heat Production in Azerbaijan

Taking use of Azerbaijan's advantageous geographic and climatic characteristics, this thesis investigates the potential of solar energy for the generation of heat and electricity in the nation. In order to assess the viability of solar photovoltaic (PV) systems for electricity production and solar thermal technologies for heating, it evaluates important places with significant sun insolation. The report points up difficulties including geographical variations in solar radiation and infrastructural constraints, but it also implies that these obstacles may be addressed by technical innovation and strategic planning. Azerbaijan's energy security and sustainability may be enhanced by implementing hybrid systems, supporting policies, and infrastructural enhancements that optimize the use of solar energy.

Tissue Oedema Following Pulsed Field Ablation Recognized during a Concomitant Left Atrial Appendage Closure Procedure. A Case Report

Abstract Background In patients with non-valvular atrial fibrillation (AF), at high stroke risk and who are ineligible for long-term oral anticoagulation the left atrial appendage closure (LAAC) could be an alternative to anticoagulation. Pulsed field ablation (PFA) is a new nonthermal method for cardiac ablation modality based on high-voltage electrical energy for irreversible electroporation. We first report a case of a concomitant PFA pulmonary vein isolation and LAAC. Case Summary A 74-year-old female patient was referred to our department for pulmonary vein isolation (PVI) for persistent AF (CHA2DS2-VASc Score 5). A concomitant percutaneous LAAC was proposed because of a history of previous cerebellar transient ischemic attack despite continuous oral anticoagulation therapy. PVI was achieved with a pentaspline PFA catheter, LAAC performed with a WATCHMAN FLXTM device (Boston Scientific, Plymouth, MN, USA). After PVI, a swelling of the left atrial ridge was observed, yet a 27 mm LAAC device was successfully implanted. The follow-up transesophageal echo (TEE) after 6 weeks showed complete resolution of the oedema, no device related thrombus but a slight proximal tilting of the LAAC device without leakage could be observed. The 6-month follow-up demonstrated a stable sinus rhythm, no stroke or bleeding events were recorded. Discussion In this case of synchronous PFA-PVI procedure in AF and Watchman FLXTM device implantation, the electroporation created an acute oedema at the ridge level which at the TEE follow-up after 6 weeks was resolved. This resulted in a slightly tilted Watchman device position which was nevertheless stable and showed no leakage.

Unveiling the Multifunctional Carbon Fiber Structural Battery.

Structural batteries refer to the multifunctional device capable of both storing electrical energy and bearing mechanical loads concurrently. In this context, carbon fibers emerge as a compelling choice of material and serve dual purpose by storing energy and providing stiffness and strength to the battery. Previous investigation has demonstrated proof-of-concept of functional positive electrodes against metallic lithium in structural battery electrolyte. Here, an all-carbon fiber-based structural battery is demonstrated utilizing the pristine carbon fiber as negative electrode, lithium iron phosphate (LFP)-coated carbon fiber as positive electrode, and a thin cellulose separator. All components are embedded in structural battery electrolyte and cured to provide rigidity to the battery. The energy density of structural battery is enhanced by use of the thin separator. The structural battery composite demonstrates an energy density of 30Whkg-1 and cyclic stability up to 1000 cycles with ≈100% of Coulombic efficiency. Remarkably, the elastic modulus of the all-fiber structural battery exceeds 76GPa when tested in parallel to the fiber direction - by far highest till date reported in the literature. Structural batteries have immediate implication in replacing structural parts of electric vehicles while reducing the number of conventional batteries. Thus, offering mass savings to future electric vehicles.

Study on the Prediction of Launcher Efficiency of Electromagnetic Launcher Based on Particle Swarm Optimization-Improved BP Neural Network

Launcher efficiency is an important index for evaluating the performance of the electromagnetic launcher, and it reflects the ability of the launcher to convert input electrical energy into kinetic energy of the armature. In this paper, the launcher efficiency is taken as the objective function of bore parameter optimization, and particle swarm optimization is used to optimize the initial parameters of the BP neural network to improve the accuracy of the neural network in predicting launcher efficiency. The results show the following: (1) The predicted efficiency of the launcher shows the same trend as the experimental results. When the ratio of rail separation and rail height is greater than 1.75, the rate of change in the launcher efficiency curve decreases as the rail separation increases. (2) The weight of the influence of each parameter on the launcher efficiency follows the following law: convex arc height > rail separation > rail height > rail thickness. (3) The mean absolute error of the BP neural network prediction is 0.70%; after optimization by PSO, the mean absolute error is reduced to 0.28% and the mean relative accuracy is improved from 0.9774 to 0.9910, which indicates the feasibility of the PSO-BP neural network for the prediction of the launcher efficiency of an electromagnetic launcher.

Constrained Model Predictive Control for Generation Power Distribution on Aircraft Engines

Aiming at the increasing demand for electric energy in aircraft in the future, a multi-objective optimization aircraft engine constrained model predictive control method based on generation power distribution is proposed. Firstly, based on the aircraft engine component level model and the equilibrium manifold theory, the aircraft engine equilibrium manifold expansion model is established. Secondly, the influence of the power generation is modeled, and the influence of the low- and high-pressure shaft generators on the normal operation of the aircraft engine is studied and compared. The control variables such as fuel flow and total generation power are taken as the constraint conditions to design the constraint model predictive controller. Furthermore, the multi-objective grey wolf optimization algorithm is introduced to intelligently optimize the parameters of the designed controller. At last, the simulation based on the component level model shows that the high-pressure shaft generator has less influence on the state quantity, including engine thrust, than the low-pressure shaft generator. The proposed control method using the multi-objective gray wolf optimization (MOGWO) algorithm has rapid response and no steady-state error.

Probabilistic co‐expansion planning for natural gas and electricity energy systems with wind curtailment mitigation considering uncertainties

Probabilistic co‐expansion planning for natural gas and electricity energy systems with wind curtailment mitigation considering uncertainties

Biowaste-Derived Triboelectric Nanogenerators for Emerging Bioelectronics.

Triboelectric nanogenerators (TENGs) combine contact electrification and electrostatic induction effects to convert waste mechanical energy into electrical energy. As conventional devices contribute to electronic waste, TENGs based on ecofriendly and biocompatible materials have been developed for various energy applications. Owing to the abundance, accessibility, low cost, and biodegradability of biowaste (BW), recycling these materials has gained considerable attention as a green approach for fabricating TENGs. This review provides a detailed overview of BW materials, processing techniques for BW-based TENGs (BW-TENGs), and potential applications of BW-TENGs in emerging bioelectronics. In particular, recent progress in material design, fabrication methods, and biomechanical and environmental energy-harvesting performance is discussed. This review is aimed at promoting the continued development of BW-TENGs and their adoption for sustainable energy-harvesting applications in the field of bioelectronics.

A Thermosensitive Ionic Hydrogel for Thermotropic Smart Windows With Integrated Thermoelectric Energy Harvesting Capability

AbstractHarvesting low‐grade waste heat into electrical energy is recognized as a promising solution for sustainable energy supply. In parallel, thermotropic smart windows have emerged as an efficient way to reduce building energy consumption. It is posit that thermotropic smart windows with inherent thermoelectric property may offer unique advantages for practical applications. Herein, the preparation and characterization of a series of ionic hydrogels that exhibit temperature‐sensitive phase transition behavior is reported, which are suitable for both thermotropic smart windows and thermoelectric generators. Notably, the lower critical solution temperature (LCST) of this ionic hydrogels can be feasibly modulated, and the thermoteopic phase transition also induces a sharp increase in their Seebeck coefficient, reaching up to 39.03 mV K−1 with a power factor (PFi) value up to 0.838 mW m−1 K−2. A prototype dual functional thermotropic smart window that simultaneously works as an ionic thermoelectric generator is further demonstrated, achieving both efficient phase transition driven by solar heat at ≈26 °C and an energy density up to 250 mJ m−2. This study offers new opportunity for the development of smart materials that can bridge the gap between thermal comfort and energy sustainability for energy harvesting and smart building applicat.

Mechanical-electric-magnetic-thermal coupled enriched finite element method for magneto-electro-elastic structures

Abstract Magneto-electro-elastic (MEE) materials possess the ability to convert mechanical, electrical, and magnetic energies, playing a critical role in smart devices. To improve the accuracy and efficiency of solving the mechanical properties of MEE structures in mechanical-electrical-magnetic-thermal (MEMT) environments, an MEMT coupled multiphysics enriched finite element method (MP-EFEM) is proposed. Based on the fundamental equations and boundary conditions of MEE materials, the interpolation coverage function is introduced into the MEMT coupled finite element method (FEM) to construct higher-order approximate interpolation displacement shape functions, electric potential shape functions, and magnetic potential shape functions. Combined with the variational principle, MP-EFEM is proposed, and the governing equations of MP-EFEM are derived. Numerical examples validate the accuracy and high efficiency of MP-EFEM in solving the mechanical properties of MEE structures in MEMT environments. When compared to the MEMT coupled FEM (MEMT-FEM), the results show that this method offers higher accuracy and efficiency. Therefore, MP-EFEM can effectively analyze the mechanical properties of MEE structures under multiphysics coupling, providing a new method for the design and development of smart devices.