Supercapacitor-based Energy Storage Research Articles

Neural Network Energy Management-Based Nonlinear Control of a DC Micro-Grid with Integrating Renewable Energies

The broad acceptance of sustainable and renewable energy sources as a means of integrating them into electrical power networks is essential to promote sustainable development. Microgrids using direct currents (DCs) are becoming more and more popular because of their great energy efficiency and straightforward design. In this work, we discuss the control of a PV-based renewable energy system and a battery- and supercapacitor-based energy storage system in a DC microgrid. We describe a hierarchical control approach based on sliding-mode controllers and the Lyapunov stability theory. To balance the load and generation, a fuzzy logic-based energy management system has been created. Using a neural network, maximum power defects for the PV system were determined. The global asymptotic stability of the framework has been verified using Lyapunov stability analysis. In order to simulate the proposed DC microgrid and controllers, MATLAB/SimulinkR (2019a) was utilized. The outcomes show that the system operates effectively with changing production and consumption.

Grid Resilience Enhancement and Stability Improvement of an Autonomous DC Microgrid Using a Supercapacitor-Based Energy Storage System

Grid Resilience Enhancement and Stability Improvement of an Autonomous DC Microgrid Using a Supercapacitor-Based Energy Storage System

Polymer Waste Valorization into Advanced Carbon Nanomaterials for Potential Energy and Environment Applications.

The rise in universal population and accompanying demands have directed toward an exponential surge in the generation of polymeric waste. The estimate predicts that world-wide plastic production will rise to ≈590 million metric tons by 2050, whereas 5000 million more tires will be routinely abandoned by 2030. Handling this waste and its detrimental consequences on the Earth's ecosystem and human health presents a significant challenge. Converting the wastes into carbon-based functional materials viz. activated carbon, graphene, and nanotubes is considered the most scientific and adaptable method. Herein, this world provides an overview of the various sources of polymeric wastes, modes of build-up, impact on the environment, and management approaches. Update on advances and novel modifications made in methodologies for converting diverse types of polymeric wastes into carbon nanomaterials over the last 5 years are given. A remarkable focus is made to comprehend the applications of polymeric waste-derived carbon nanomaterials (PWDCNMs) in the CO2 capture, removal of heavy metal ions, supercapacitor-based energy storage and water splitting with an emphasis on the correlation between PWDCNMs' properties and their performances. This review offers insights into emerging developments in the upcycling of polymeric wastes and their applications in environment and energy.

Exploring the Synergistic Structural and Optical Properties of Co-Precipitated BiCr2O4/GO Nanocomposite

Binary nanocomposite of BiCr2O4/GO synthesized by co-precipitation method where BiCr2O4 was synthesized by sol-gel and GO was prepared by Hummer’s method has been reported. From XRD analysis, average crystalline size of GO, BiCr2O4 and BiCr2O4/GO are 5.55 nm, 6.85 nm and 5.27 nm respectively. From SEM micrograph it is quite clear that BiCr2O4/GO nanoparticles retain their quasi spherical grains with in the nanocomposite whereas as the presence of Bi, Cr and Si were evident from EDS spectra resulting GO suppressed peak. PL spectra for binary BiCr2O4/GO nanocomposite shows the estimated band gap energy of 3.5 eV which lies in the band gap energy range of GO about 3.1–3.9 eV. Bond formation in BiCr2O4/GO nanocomposite was depicted by Raman band shift. These all results support nanocomposite based nanomaterial suitability for its application in supercapacitor based energy storage materials.

Recent Trends in Highly Porous Structured Carbon Electrodes for Supercapacitor Applications: A Review

Globally, environmental and energy conservation concerns have sparked a push for more efficient and long-term energy sources. Researchers worldwide have put significant effort into developing supercapacitor-based energy storage devices by fabricating electrode materials from affordable porous carbon. The advantages of porous carbons are low-cost processes, high porosity, high surface area, facilitation of surface modification, high conductivity, high mechanical stability, high chemical stability, facilitation of fast ion transport, high rate capability, and high specific capacitance. Using them as electrodes in supercapacitors (SCs) may lead to better performance in specific capacitance and long-term cyclic stability. This study focuses on the recent development of electrode materials for SCs using porous carbons obtained from several diverse sources, such as biomass, polymers, lignite, metal salts, melamine, etc. Therefore, the topic of this review is the most current development of electrode materials for SCs applications. SCs were subjected to a battery of electrochemical tests, which focused on their performance from a crucial perspective, concentrating on the porous carbon’s surface area and surface functional groups. The report also highlights the supercapacitor’s prospects and challenges.

Performance Evaluation of Hybrid Battery–Supercapacitor-Based Energy Storage Systems for Urban-Driven Electric Vehicles

Boosting the performance of energy management systems (EMSs) of electric vehicles (EVs) helps encourage their mass adoption by addressing range anxiety concerns. Acknowledging the higher power densities of supercapacitors (SCs) compared to those of the Lithium-ion (Li-ion) batteries used in EVs, this work proposes an optimal sizing and energy management strategy of a hierarchical hybrid energy storage system (H-HESS). In this system, the SCs are voltage-controlled to solely provide the current requirements of an EV motor during urban driving cycles with frequent accelerations and decelerations, while the EV battery recharges the depleted SCs. The proposed H-HESS is modeled and simulated on MATLAB/Simulink, and its performance is compared to that of a traditional battery-only energy storage system (BESS). Simulation results reveal that this H-HESS system offers a 55.7% peak current reduction and ≈+2% improvement in battery loss of capacity in comparison with BESS. A pulsed battery discharge current profile is imposed by the proposed H-HESS, while C-rate control is implemented. This improves the battery aging by reducing the formation of the solid electrolytic film (SEI) that otherwise decreases its capacity.

Development of supercapacitor hybrid electric vehicle

Hybrid electric vehicle needs dedicated energy storage system suitable for its special operating conditions. The nickel-metal hydride batteries and lithium-ion batteries dominate this market, but they also have some drawbacks. The electric double layer supercapacitors have been employed in passenger vehicles, but the drawbacks of those supercapacitors prevent them from the application of energy storage system for hybrid electric vehicles. A technical route of hybrid supercapacitor-based energy storage systems for hybrid electric vehicles is proposed, this kind of hybrid supercapacitor battery is composed of a mixture of supercapacitor materials and lithium-ion battery materials. We developed a supercapacitor battery cell dedicated for energy storage system of hybrid electric vehicles. The advantages of those supercapacitor cells are low cost, long life cycle, high safety, wide working temperature range, high power density and high energy density. The supercapacitor battery pack and supercapacitor hybrid electric vehicle with the developed supercapacitor cells showed great performance improvements.

Self-assembly of novel cobalt iron phosphate nanoparticles for the solid-state supercapattery and high-performance hydrogen evolution reaction

In this article, we report the preparation of novel cobalt iron phosphate nanoparticles which are self-assembled for energy storage, energy conversion, and sustainability. The self-assembled nanoparticles provide an efficient pathway for the transfer of electrons from the bulk of the materials to the interface of the electrode. This hypothesis has been derived from the analysis based on the electrochemical results for the supercapacitor-based energy storage and hydrogen evolution. The electrode consisting of self-assembled nanoparticles exhibits a maximum specific capacity of 280 C g−1 at a specific current of 1 A g−1. The cyclic voltammetric results suggest the prominent charge storage is by the faradaic reaction which has been concluded from Dunn's approach. The supercapattery device utilizing activated carbon (AC) as the negative electrode and cobalt iron phosphate as the positive electrode exhibit a specific capacity of 210 C g−1 at 2 A g−1 while the specific energy of 47.6 Wh kg-1 at 1.6 kW kg−1. Furthermore, the electrode actively catalyzes the electrochemical hydrogen evolution reaction and it can be lowering the overpotential required by the hydrogen generation. It exhibits the overpotential of 197 mV while the electrode represents the long-time (24 h) consistency for hydrogen production. These results indicate that the novel cobalt iron phosphate nanoparticles could be a potential candidate for energy storage and conversion purposes.

Laser induced graphanized microfluidic devices.

With the advent of cyber-physical system-based automation and intelligence, the development of flexible and wearable devices has dramatically enhanced. Evidently, this has led to the thrust to realize standalone and sufficiently-self-powered miniaturized devices for a variety of sensing and monitoring applications. To this end, a range of aspects needs to be carefully and synergistically optimized. These include the choice of material, micro-reservoir to suitably place the analytes, integrable electrodes, detection mechanism, microprocessor/microcontroller architecture, signal-processing, software, etc. In this context, several researchers are working toward developing novel flexible devices having a micro-reservoir, both in flow-through and stationary phases, integrated with graphanized zones created by simple benchtop lasers. Various substrates, like different kinds of cloths, papers, and polymers, have been harnessed to develop laser-ablated graphene regions along with a micro-reservoir to aptly place various analytes to be sensed/monitored. Likewise, similar substrates have been utilized for energy harvesting by fuel cell or solar routes and supercapacitor-based energy storage. Overall, realization of a prototype is envisioned by integrating various sub-systems, including sensory, energy harvesting, energy storage, and IoT sub-systems, on a single mini-platform. In this work, the diversified work toward developing such prototypes will be showcased and current and future commercialization potential will be projected.

Power system stability improvement considering drive train oscillations of virtual synchronous generator‐regulated type‐4 wind turbines

The type-4 wind turbine generators (WTGs) can provide inertial frequency response by implementing the virtual synchronous generator (VSG) concept. However, unstable torsional oscillations (TOs) would be induced in the multi-mass-spring drive-train which can destabilize the entire power system. In this study, participation factor analyses are performed for a power system inclusive of a thermal unit and aggregated WTG system. The system's eigenvalues are characterized and the possible detrimental impacts of TOs on the inertia provision process and overall power system stability are demonstrated and the related stability limits are identified. A comprehensive active torsional oscillations damper (CA-TOD) and a supercapacitor-based energy storage system (ESS) are presented and discussed to implement the CA-TOD. A state of charge (SoC) regulator is also employed to set the reference speed difference for the turbine-generator. Small-signal studies and electro-magnetic transient (EMT) simulations are performed to evaluate the functionality of the CA-TOD and SoC controller and estimate their impacts on the system's dynamics. The robust performance of the CA-TOD is compared to the band-pass filter-based TOD by sweeping key control parameters of the VSG and emulating drive-train parameter uncertainty. Key results are cross-verified by EMT simulations of a multimachine power system.

Uniform and fully decorated novel Li-doped α-Fe2O3 nanoparticles for high performance supercapacitors

Supercapacitors are considered emerging energy storage sources owing to their long-term cycling stability, high energy/power density, and rapid charge/discharge process. The performance characteristics of supercapacitors can be enhanced by devising electrodes with highly porous nanostructures through subtle hybridization of active materials and the development of current collectors with tailored nanoarchitectures. Herein, we reported the effect of Li doping on the electrochemical application of the pure α-Fe2O3 thin films. The preparation of nanoparticles-like nanostructures of the pure α-Fe2O3 and different percentages of Li-doped α-Fe2O3 thin films by cost effective and facile hydrothermal method for the supercapacitor application. As-synthesized pure α-Fe2O3 and Li doped α-Fe2O3 thin films were analyzed by the X-ray diffraction (XRD), and X-ray photoelectron (XPS) spectroscopy, scanning electron microscopy, transmission electron microscopy, and supercapacitor properties. The XRD results revealed the formation of the pure phase of the α-Fe2O3 with the rhombohedral crystal structure. XPS results confirmed the Li species existence in the 0.5% Li doped α-Fe2O3. The electrochemical properties indicate the 3D chain of the nanoparticle-like surface morphology of pure α-Fe2O3 and Li-doped α-Fe2O3 are more useful electrode materials for electrochemical application. The calculated values of the specific capacity (Cs) indicate the different percentages of doping of Li are affected by the electrochemical properties of the pure α-Fe2O3. The Cs of the optimized 0.5% Li-doped α-Fe2O3 (79 mAh g−1) electrode was 1.3-fold higher than that of the pure α-Fe2O3 electrode (52 mAh g−1) at a constant scan rate with excellent cycling stability upto 3000 cycles. The electrochemical and surface morphological analysis demonstrate that the 0.5% Li-doped α-Fe2O3 electrode is more useful than the pure α-Fe2O3 and other electrodes for developing high-rate hybrid supercapacitor-based energy storage devices applications.

Supercapacitor-Based Energy Storage in Elevators to Improve Energy Efficiency of Buildings

Improving energy efficiency is the most important goal for buildings today. One of the ways to increase energy efficiency is to use the regenerative potential of elevators. Due to the special requirements of elevator drives, energy storage systems based on supercapacitors are the most suitable for storing regenerative energy. This paper proposes an energy storage system consisting of a supercapacitor bank and a bidirectional six-phase interleaved DC/DC converter. The energy savings achieved by the proposed system were investigated through simulation tests. The proposed system was modeled considering all physical constraints. A simulation model of the existing faculty elevator system was created in PLECS and verified with field measurements. Reliable results were ensured by using the verified simulation model and considering all physical constraints. The operation of the proposed energy storage system was tested under various conditions. In addition, the simulation model of the elevator system with the proposed energy storage system was tested using the elevator traffic data obtained from the measurements. The simulation results show the effectiveness of the proposed energy storage system and that significant energy savings can be achieved.

Supercapacitor Modeling for Real-Time Simulation Applications

Supercapacitor-based energy storage systems have proved their performance in stabilizing the power system, particularly during disturbances, which require high power capability, but low energy density, such as during frequency support services. Several models have been proposed in literature to model the supercapacitors, aiming to maximize the model accuracy in the whole frequency spectrum. However, their real-time modeling has been not deeply studied, in particular, considering the real-time simulation constraints, that limit either the model details or the simulation size. This work introduces a modeling guideline for supercapacitors for real-time simulations, proposing a tradeoff between the model accuracy and the required computational time to simulate it. Compared to existing models, this work assesses their time- and frequency-domain accuracy, estimates required computational time, and recommends which model is suited for a specific power system analysis or application.

Joint coordination of optimal power management and energy storage system sizing for a full-scale marine current turbine considering microgrid integration constraint

The issues of variability and uncertainty of tidal speed result in severe challenges for standalone microgrid (as island grids for examples) operators. Indeed, to maintain the system power balance, existing classical generators which are associated with tidal power units must be able to frequently change their operating point, either up or down, to respond to the fast fluctuations of tidal power and consumption and sometimes exceed their maximal ramp capability. This in turn accelerates aging process and results in serious damage. The switching to a safer and more reliable system seems to be a promising and long-term solution. This paper proposes to associate a supercapacitor-based Energy Storage System (SC-ESS) to a tidal turbine to smooth the fast power production fluctuations. The association of this SC-ESS with the tidal turbine unit aims to meet requirements on the variation of injected tidal power in an islanded microgrid. An original smart power management strategy is proposed for the use of the ESS. Taking into account this strategy, an optimal design methodology based on simulations on the more severe encountered day cases is proposed. This methodology allows to determine a minimal sizing of the ESS to fulfil the grid requirements. The paper also proposes a complete modeling of the whole system behavior. The Energetic Macroscopic Representation (EMR) tool is used to realize the system model where the inversion-based control principle is then used to deduce the control schemes. This global methodology is applied to a test tidal turbine which is based on a real 1 MW prototype setup to the islanded grid of Ushant in France. Using real measured data, it is shown that a relatively small and low cost SCs pack is sufficient to accommodate the high tidal power fluctuations. A comparison is performed between the existing configuration where a resistor bank is used to shave the excessive power variation and the considered case where SCs pack is used. For one tidal cycle, it is shown that a reduction in energy loss of 18.2% is achieved, which presents a non-negligible gain for Ushant's Island microgrid.

Electrical and Mathematical Modeling of Supercapacitors: Comparison

Supercapacitors are energy storage devices with high electrical power densities and long spanlife. Therefore, supercapacitor-based energy storage systems have been employed for a variety of applications. The modelling and simulation of SCs have been of great interest to this objective. This paper presents an electrical schema and mathematical modelling of three models of supercapacitors. The first is the RC model, the second is the two-branch model and the third is the multi-branch model. The objective of this modelling is to choose the best model that can respect the same behaviour of the experimental model. These models are compared with an experimental model. This comparison prove that the response voltage of the multi-branch model correctly describes the behaviour of the experimental model of Belhachemi. The disadvantage of this model is the slow simulation duration in MATLAB/Simulink. The RC model represented the faster model in terms of simulation. The choice of 15 branches in parallel in multi-branch models gives good results and correctly describes the reel model. The automatic charge and discharge voltage of SCs reduce by reducing the charge current.

Experimental characterization of a PEM fuel cell for marine power generation

This study is focused on the possible application of hydrogen-fed PEM fuel cells on board ships. For this purpose, a test plant including a 100 kW generator suitable for marine application and a power converter including a supercapacitor-based energy storage system has been designed, built and experimentally characterised. The plant design integrates standard industrial components suitable for marine applications that include the technologies with the highest degree of maturity currently available on the market. Fuel Cell generator and power converter have been specifically designed by manufacturers to fit the specific plant needs. The experimental characterisation of the plant has been focused on the evaluation of the efficiency of the single components and of the overall system. Results shows a PEM fuel cell efficiency of 48% (when all auxiliaries are included) and an overall plant efficiency, including power conditioning, of about 45%. From load variation response tests, the fuel cell response time was maximum 2 seconds without supercapacitors and increased up to 20 seconds with supercapacitors connected, reducing the stress on the fuel cell generator. Experimental results confirm that PEM fuel cells, when supported by a suitably sized energy storage system, represent a viable technical solution for zero-emission power generation on board ships.

High performance and remarkable cyclic stability of a nanostructured RGO-CNT-WO3 supercapacitor electrode.

One of the most pressing concerns in today's power networks is ensuring that consumers (both home and industrial) have access to efficient and long-lasting economic energy. Due to improved power accessibility and high specific capacitance without deterioration over long working times, supercapacitor-based energy storage systems can be a viable solution to this problem. So, here, tungsten trioxide (WO3) nanocomposites containing reduced graphene oxide and carbon nanotubes i.e. (RGO-WO3), (CNT-WO3), and (RGO–CNT-WO3), as well as pure WO3 nanostructures as electrode materials, were synthesized using a simple hydrothermal process. The monoclinic phase of WO3 with high diffraction peaks is visible in X-ray diffraction analysis, indicating good crystallinity of all electrode materials. Nanoflowers of WO3 were well-decorated on the RGO/CNTs conductive network in SEM micrographs. In a three-electrode system, the specific capacitance of the RGO–CNT-WO3 electrode is 691.38 F g−1 at 5 mV s−1 and 633.3 F g−1 at 2 A g−1, which is significantly higher than that of pure WO3 and other binary electrodes. Furthermore, at 2 A g−1, it achieves a coulombic efficiency of 98.4%. After 5000 cycles, RGO–CNT-WO3 retains 89.09% of its capacitance at 1000 mV s−1, indicating a promising rate capability and good cycling stability performance.

Two-Stage Synthetic Optimization of Supercapacitor-Based Energy Storage Systems, Traction Power Parameters and Train Operation in Urban Rail Transit

The stationary supercapacitor energy storage system (SCESS) is one of effective approaches for the utilization of train's regenerative braking energy in urban rail systems. In this paper, the capacity configuration of SCESSs, the no-load voltage of substation, the control of onboard braking resistors and train operation diagrams are considered comprehensively. Based on the equivalent circuit model, the effects of traction power system parameters on the energy transmission between powering trains, braking trains and SCESSs are analyzed, and the relationships between the train operating parameters and system energy consumptions are revealed. A multi-variable synthetic optimization method is proposed to optimize the SCESS capacity, train operation diagrams and traction power system parameters collaboratively. In order to reduce the search space and improve the efficiency of the optimization algorithm, a hierarchical multi-objective optimization model is established, based on which the design variables and the control variables are optimized iteratively. And as the traffic density has a great impact on the regenerative braking energy distribution of the system, the optimization objective function fully considers the frequency distribution of headways throughout the day. Combined the Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) with the traction power flow simulator, the flowchart of the two-stage optimization algorithm is designed, and the pareto set of the multi-objective problem is obtained. The advantages of reducing system energy consumptions and configuration cost under the proposed algorithm are verified based on case studies of Beijing Batong Line.

Graphene with Covalently Grafted Amino Acid as a Route Toward Eco-Friendly and Sustainable Supercapacitors.

Eco‐friendly, electrochemically active electrode materials based on covalent graphene derivatives offer enormous potential for energy storage applications. However, covalent grafting of functional groups onto the graphene surface is challenging due to its low reactivity. Here, fluorographene chemistry was employed to graft an arginine moiety via its guanidine group homogeneously on both sides of graphene. By tuning the reaction conditions and adding a non‐toxic pore‐forming agent, an optimum degree of functionalization and hierarchical porosity was achieved in the material. This tripled the specific surface area and yielded a high capacitance value of approximately 390 F g−1 at a current density of 0.25 A g−1. The applicability of the electrode material was investigated under typical operating conditions by testing an assembled supercapacitor device for up to 30000 charging/discharging cycles, revealing capacitance retention of 82.3 %. This work enables the preparation of graphene derivatives with covalently grafted amino acids for technologically important applications, such as supercapacitor‐based energy storage.

Artificial intelligence-based nonlinear control of renewable energies and storage system in a DC microgrid

To minimize the global warming and the impact of greenhouse effect, renewable energy sources-based microgrids are widely studied. In this paper, the control of PV, wind-based renewable energy system and battery, supercapacitor-based energy storage system in a DC microgrid have been presented. Maximum power points for PV and wind have been obtained using neural network and optimal torque control, respectively. Nonlinear supertwisting sliding mode controller has been presented for the power sources. Global asymptotic stability of the framework has been verified using Lyapunov stability analysis. For load-generation balance, energy management system based on fuzzy logic has been devised and the controllers have been simulated using MATLAB/Simulink® (2019a) along with a comparison of different controllers. For the experimental validation, controller hardware-in-the loop experiment has been carried out which validates the performance of the designed system.