Internal Energy Storage Research Articles

Mechanisms of Thermal Decomposition in Spent NCM Lithium-Ion Battery Cathode Materials with Carbon Defects and Oxygen Vacancies.

Resource recovery from retired electric vehicle lithium-ion batteries (LIBs) is a key to sustainable supply of technology-critical metals. However, the mainstream pyrometallurgical recycling approach requires high temperature and high energy consumption. Our study proposes a novel mechanochemical processing combined with hydrogen (H2) reduction strategy to accelerate the breakdown of ternary nickel cobalt manganese oxide (NCM) cathode materials at a significantly lower temperature (450 °C). Particle refinement, material amorphization, and internal energy storage are considered critical success factors for the accelerated decomposition of NCM cathode materials. In our proposed approach, NCM cathode materials can develop active sites with carbon defects (Cv) and oxygen vacancies (Ov), which improve the reduction and breakdown of H2. The adsorbed H2 on the surface of NCM decomposes into H* and combines with oxygen to form OH species, which can be facilitated by Ov via the enhanced charge transfer. The introduced Cv can enhance H2 cracking and generate *C-H species to promote the thermal decomposition of NCM. The presence of defects proves to foster the preferential reduction of Mn(IV) by H2, leading to a lower activation energy for the NCM decomposition (from 139 to 110 kJ/mol) with less H2 consumption. Life cycle assessment suggests a reduction of 4.42 kg CO2 eq for the recycling of every 1.0 kg of retired batteries. This study can promote material circularity and minimize the environmental burden of mining technology-critical metals for a low-carbon transition.

Collaborative optimization of electric-vehicle battery swapping stations based on energy storage sharing

Due to the extensive integration of distributed renewable energy resources, the Active Distribution Network (ADN) faces numerous challenges, including, for example, renewable energy curtailment and overloading. This paper proposes a collaborative optimization control method for electric-vehicle battery swapping stations that mitigates the mismatching between generation and load demand in the ADN. Energy storage sharing is considered in this study, that allows stations to exchange batteries via the traffic network, and this extends the capacity of Battery-Transferable Swapping Stations (BTSSs). First, the operational principles of the energy storage shared BTSS are carefully analyzed, including external and internal control mechanisms and energy storage sharing. Subsequently, a bi-level optimization model is proposed, whereby the upper level aims to minimize the total operational cost of the ADN and the lower level seeks to maximize the benefit of each BTSS. A two-stage transactive control is introduced to decompose the bi-level situation into two stages: the day-ahead stage and the real-time stage and this facilitates easier problem-solving. Finally, an IEEE 15-node system is utilized to verify the proposed method. The results indicate that the proposed method reduces the renewable energy curtailment, power shortages, and operational costs of the ADN, while at the same time increasing the earnings of BTSSs.

Octopamine integrates the status of internal energy supply into the formation of food-related memories

The brain regulates food intake in response to internal energy demands and food availability. However, can internal energy storage influence the type of memory that is formed? We show that the duration of starvation determines whether Drosophila melanogaster forms appetitive short-term or longer-lasting intermediate memories. The internal glycogen storage in the muscles and adipose tissue influences how intensely sucrose-associated information is stored. Insulin-like signaling in octopaminergic reward neurons integrates internal energy storage into memory formation. Octopamine, in turn, suppresses the formation of long-term memory. Octopamine is not required for short-term memory because octopamine-deficient mutants can form appetitive short-term memory for sucrose and to other nutrients depending on the internal energy status. The reduced positive reinforcing effect of sucrose at high internal glycogen levels, combined with the increased stability of food-related memories due to prolonged periods of starvation, could lead to increased food intake.

Octopamine integrates the status of internal energy supply into the formation of food-related memories.

The brain regulates food intake in response to internal energy demands and food availability. However, can internal energy storage influence the type of memory that is formed? We show that the duration of starvation determines whether Drosophila melanogaster forms appetitive short-term or longer-lasting intermediate memories. The internal glycogen storage in the muscles and adipose tissue influences how intensely sucrose-associated information is stored. Insulin-like signaling in octopaminergic reward neurons integrates internal energy storage into memory formation. Octopamine, in turn, suppresses the formation of long-term memory. Octopamine is not required for short-term memory because octopamine-deficient mutants can form appetitive short-term memory for sucrose and to other nutrients depending on the internal energy status. The reduced positive reinforcing effect of sucrose at high internal glycogen levels, combined with the increased stability of food-related memories due to prolonged periods of starvation, could lead to increased food intake.

Effect of continuous extrusion forming on mechanical properties of aged Cu-Ni-Si alloy

Cu-Ni-Si alloy is extensively utilized as the main material for lead frames, and its preparation process and mechanical properties are closely related. In this work, two processing routes were employed to prepare Cu-1.8Ni-0.45Si alloys. One (named traditional processing, TP) involves vacuum casting followed by hot rolling, while the other (named short processing, SP) involves downward continuous casting and CONFORM. The variation trend and mechanism of its tensile strength and elongation were analyzed by SEM, EBSD and TEM. The results showed that the tensile properties of Cu-1.8Ni-0.45Si alloy were greatly improved after CONFORM treatment. CONFORM enables Cu-1.8Ni-0.45Si alloy to facilitates enhanced internal deformation energy storage and grain boundary density in the matrix after cold deformation, making it easier for the aging process to further precipitate and grow Ni2Si phase. Compared with TP, the tensile strength of the alloy decreases slightly, but the elongation increases significantly.

Research on the Cold Storage Characteristics of Ice Storage Photovoltaic Cold Storage

The ice-on-coil storage tank is one of the core devices in the latent heat cold storage system. The main objective of this study is to couple the solar photovoltaic cold storage with Cold Thermal Energy Storage technology. The internal ice-melting coil energy storage system used the water as a heat transfer fluid for adopting a day and night cold storage control strategy. The experiments were conducted for several days under the conditions of photovoltaic-driven cold storage with and without load for a continuous cold storage. The reasons for the occurrence of ice layers during ice accumulation and melting, as well as the operational economy of the system were analyzed. Moreover, the characteristics of the cold storage tank were summarized. Consequently, when the external ice thickness of the coil was within the range of 27 to 32mm, the ice storage rate reached 35.82% and achieved the optimal refrigeration efficiency in both the coil and the cold storage. The daily ice production in the cold storage tank decreased by an average of 22.06% during continuous operation with load compared to the unloaded operation. However, the daily refrigeration capacity increased by 45.774%. In addition, when cold thermal energy storage was coupled with solar photovoltaic technology, the refrigeration capacity decreased by 7.15% compared to using Cold Thermal Energy Storage technology alone, which resulting in an annual electricity cost saving of 30.20%.

Toward local Madelung mechanics in spacetime

It has recently been shown that relativistic quantum theory leads to a local interpretation of quantum mechanics wherein the universal wavefunction in configuration space is entirely replaced with an ensemble of local fluid equations in spacetime. For want of a fully relativistic quantum fluid treatment, we develop a model using the nonrelativistic Madelung equations, and obtain conditions for them to be local in spacetime. Every particle in the Madelung fluid is equally real, and has a definite position, momentum, kinetic energy, and potential energy. These are obtained by defining quantum momentum and kinetic energy densities for the fluid and separating the momentum into average and symmetric parts, and kinetic energy into classical kinetic and quantum potential parts. The two types of momentum naturally give rise to a single classical kinetic energy density, which contains the expected kinetic energy, even for stationary states, and we define the reduced quantum potential as the remaining part of the quantum kinetic energy density. We treat the quantum potential as a novel mode of internal energy storage within the fluid particles, which explains most of the nonclassical behavior of the Madelung fluid. For example, we show that in tunneling phenomena, the quantum potential negates the barrier so that nothing prevents the fluid from flowing through. We show how energy flows and transforms in this model, and that enabling local conservation of energy requires defining a quantum potential energy current that flows through the fluid rather than only flowing with it. The nonrelativistic treatment generally contains singularities in the velocity field, which undermines the goal of local dynamics, but we expect a proper relativistic treatment will bound the fluid particle velocities at c.

Thermodynamic trends for evaluating hydrogen storage density and energy flow on Maxsorb-III, HKUST-1 and UiO-66 (Zr) MOFs

For CO2-free power generation in power plants or vehicles, hydrogen should be implemented as H2 possesses not only the highest energy density (120 MJ/kg) but also can be generated from the environment and reactions. However, H2 is difficult to store due to its low density at ambient conditions. To understand the efficacy of hydrogen interactions in porous materials including the randomness of hydrogen adsorption in terms of storage density, energy flow and dissipation, a thermodynamic study is required. This paper at first focuses on the study of H2 adsorption on various porous adsorbents such as activated carbons (AC types Maxsorb-III) and metal–organic frameworks (types UiO-66 (Zr) and HKUST-1 MOFs) and the results are presented in temperature-density co-ordinate system. Employing experimentally confirmed isotherms data of AC/MOFs + H2 systems, the density of H2 adsorbed phase, entropy flow and generation are evaluated. These results indicate the feasibility of hydrogen adsorption on functional adsorbents at various temperature and pressure. The simulation results show that the adsorbed phase densities of H2 on Maxsorb-III and HKUST-1 increase up to 18 kg/m3 and 20 kg/m3 at 5 bar and 77 K. The temperature-entropy diagram shows a close loop for the charging and discharging of hydrogen and ensures the storage of internal energy with less entropy dissipation under cryo-adsorption conditions.

A novel demand response-based distributed multi-energy system optimal operation framework for data centers

To address the increasing energy demands in data centers, distributed multi-energy system (DMES) can provide an efficient solution. This study proposes a DMES coupled by photovoltaics, wind turbines, ground source heat pump, internal combustion engines, electric chillers, absorption chillers, and energy storage device. The optimal scheduling of DMES with source-load interaction plays a crucial role in improving the performance of data centers. To achieve this, an integrated demand response (IDR) strategy is established, considering time-of-use pricing and renewable energy peak subsidies. Then, a clean and economical optimal operation model for DMES based on proposed IDR strategy and carbon trading mechanisms is established. Furthermore, to enhance the robustness of scheduling, this study analyzes the impacts of uncertainties in renewable energy output and demand response on DMES operation using the Monte Carlo method and interval method. Case study results demonstrate that the proposed IDR strategy increases electricity and cooling loads while reducing heat loads during the peak period of renewable energy generation, compared to the traditional IDR strategy. The proposed scheduling model, which incorporates the proposed IDR strategy and carbon trading mechanism, improves data center performance by reducing total costs by 1.85%, carbon emissions by 0.56%, electricity purchases by 2.93%, while increasing renewable energy utilization by 0.77%. The results also highlight the critical role of energy storage devices, with an optimal initial charge state is 0.5. Additionally, optimization considering multiple uncertainties, results in higher total costs and broader interval widths compared to single-factor uncertainty optimization, but reduces system operational risk.

Xenon storage density and its energy flow through adsorption on metal–organic frameworks

The global demand for Xe storage and separation increases significantly over the coming decades for various applications ranging from ion propulsion to nuclear power plants. Due to very low amount of Xe in the earth's atmosphere and the complexity of cryogenic storage facilities, the storage and recovery of Xe in porous adsorbents such as MOFs (metal–organic frameworks) are an important research area. The research activities on adsorption-assisted Xe storage include (i) the synthesis of adsorbents with greater micropore distribution and large micropore volume and (ii) the Xe storage capability in the form of isotherms and kinetics. But the thermodynamic properties such as enthalpy, internal energy, entropy and density can judicially be applied to simulate the energetic and storage performances of Xe gas in structural porous adsorbents. Therefore, this manuscript presents the thermodynamic formulations of entropy flow, generation and adsorbed phase density of MOFs + Xe systems. Secondly, these parameters are evaluated for Xe adsorption on MIL-100 (Fe), MIL-101(Cr), UiO-66(Zr) and FMOF(Zn) MOFs at temperatures changing from 233 K to 303 K and pressures up to 100 kPa. A deeper understanding of Xe storage capacity on MOFs is presented by temperature–density maps. Furthermore, the entropy and temperature maps are plotted to identify the internal energy storage capacity of Xe in MOFs storage cells under charging and discharging conditions of Xe.

Research on Multi-objective Optimal Configuration of Distributed Energy Storage System

The purpose is to improve the absorption capacity of new energy generation added to the power system, the distributed energy storage system (ESS) is introduced. Considering the new energy generation as the main distributed power supply is united to the power grid, the mathematical model of wind-photoelectric-energy storage system is constructed. Taking active power loss, voltage offset and comprehensive cost as objectives, a multi-objective internal and external layer optimization energy storage device configuration model is established. The outer layer uses branch and bound method to locate the location of energy storage. In the inner layer, NSGA-II algorithm is used to optimize the capacity and the situation of storing or releasing power. Eventually, the IEEE 30 node test system with distributed power supply is used for simulation, and the optimal location, capacity and charging/discharging strategy of the ESS in the grid topology are obtained. The results verify the rationality of the configured energy storage, and show that system can absorb distributed energy to a certain extent.

Thermal characteristics of pouch lithium–ion battery capacitors based on activated carbon and LiNi1/3Co1/3Mn1/3O2

Lithium–ion battery capacitors (LIBCs) are internal hybrid energy storage devices that incorporate structural characteristics of lithium–ion batteries (LIBs) and lithium–ion capacitors (LICs) for extensive applications in electric vehicles and energy storage systems. But, most of the existing researches have concentrated on the electrochemical performance of LIBC cells, with less research on thermal behaviors of them. Therefore, this work systematically investigates the thermal characteristics of LIBC cells during discharge from 1C to 160C. The discharge capacity is reduced along with an increase in discharge rate, with the highest temperature occurring at 80C discharge rate, where it reaches 51.74 °C. The share of irreversible heat generation, reversible heat generation and other heat generation with respect to total heat generation are quantified. With the discharge rate increasing to 160C, the share of irreversible heat generation is nearly 89.2 % of the total heat generation. Meanwhile, it obtains 263.21 W heat generation rate. Moreover, the LIBC cell's internal resistance is obtained by intermittent current method and electrochemical impedance spectroscopy (EIS) method, while the heat generation is calculated to estimate cell's temperature rise. The intermittent current method makes possible the selection of various timescales for calculating the polarization internal resistance with more accurate calculation of the temperature rise.

Selective Extraction of Critical Metals from Spent Lithium-Ion Batteries.

Selective and highly efficient extraction technologies for the recovery of critical metals including lithium, nickel, cobalt, and manganese from spent lithium-ion battery (LIB) cathode materials are essential in driving circularity. The tailored deep eutectic solvent (DES) choline chloride-formic acid (ChCl-FA) demonstrated a high selectivity and efficiency in extracting critical metals from mixed cathode materials (LiFePO4:Li(NiCoMn)1/3O2 mass ratio of 1:1) under mild conditions (80 °C, 120 min) with a solid-liquid mass ratio of 1:200. The leaching performance of critical metals could be further enhanced by mechanochemical processing because of particle size reduction, grain refinement, and internal energy storage. Furthermore, mechanochemical reactions effectively inhibited undesirable leaching of nontarget elements (iron and phosphorus), thus promoting the selectivity and leaching efficiency of critical metals. This was achieved through the preoxidation of Fe and the enhanced stability of iron phosphate framework, which significantly increased the separation factor of critical metals to nontarget elements from 56.9 to 1475. The proposed combination of ChCl-FA extraction and the mechanochemical reaction can achieve a highly selective extraction of critical metals from multisource spent LIBs under mild conditions.

Powering Solutions for Biomedical Sensors and Implants Inside the Human Body: A Comprehensive Review on Energy Harvesting Units, Energy Storage, and Wireless Power Transfer Techniques

For implantable medical devices, it is of paramount importance to ensure uninterrupted energy supply to different circuits and subcircuits. Instead of relying on battery stored energy, harvesting energy from the human body and any external environmental sources surrounding the human body ensures prolonged life of the implantable devices and comfort of the patients. In this article, we present existing issues and challenges related to the state-of-the-art solutions used for harvesting energy to power implantable devices. In addition, the details on existing energy storage technologies and various wireless power transfer techniques incorporating external or internal energy sources and sensors have been discussed. The authors have outlined the performance and power constraints of existing biomedical devices and provided a brief overview of various power architectures found in the literature. This survey has been conducted on existing implantable solutions in terms of output voltage, current, device dimension, application, generated power, energy density, and so on. Finally, the advantages and drawbacks of different solutions have been discussed and compared. Therefore, this article can be considered as an expedient reference for researchers conducting research in the field of energy scavenging, internal energy storage, wireless power transfer techniques, and power management of implantable medical devices.

Planning of Flexible Generators and Energy Storages under High Penetration of Renewable Power in Taiwan Power System

The proportion of renewable power generation in the world has been increasing in recent years. However, the fluctuations and uncertainties of renewable power generation bring a considerable challenge to future unit scheduling. Therefore, the generation flexibility in power systems becomes more critical as a large amount of renewable generation is integrated into power systems. The use of flexible generators with energy storage systems is one of the most efficient methods of improving power system flexibility. The primary purpose of this study is to explore the effect of generation flexibility on the cost of unit scheduling. A flexibility index is used to evaluate the generation flexibility in the Taiwan power system, and a multi-scenario analysis for renewable power integration is considered. This study also considers various system constraints, such as the unit commitment of actual hydro and thermal units, the scheduling of flexible internal combustion engines (ICEs) and energy storage systems, and possible curtailments of renewable power generation. According to the seasonable characteristics of renewable power generation, this study provides a suitable capacity for flexible ICE units and energy storage systems. Furthermore, this study demonstrates that the cost of unit scheduling is effectively reduced by increasing flexible ICE units and energy storage systems. The results of this study can be used as a reference for power systems in preparing flexible generating units and energy storage systems under the integration of a large amount of renewable power generation in the future.

A hybrid concentrated solar/biomass combustion system with internal thermal energy storage for fully dispatchable renewable electricity production in Mauritius

AbstractWind and solar photovoltaic need expensive battery energy storage for dispatchability. Concentrated solar power plus internal thermal energy storage permits dispatchability, but it is convenient only in areas of large direct normal irradiance. A hybrid concentrated solar/combustion system is proposed for Mauritius, an area of modest direct normal irradiance, and biomass availability. The small, modular, 8 kW system for microgrid application comprises a beam down point concentrator, two tanks of molten salt thermal energy storage, a biomass combustion heater, a Stirling engine, and a generator. The hybrid system has a thermal energy supply solar of 41%, and a thermal energy supply by combustion fuel 59%. By assuming a zero CO2e emission for solar thermal energy supply (100% reduction of CO2e) and a 21% CO2e emission for thermal energy from the combustion of bagasse (79% reduction) vs thermal energy from oil combustion, the proposed hybrid device would permit an 88% reduction of the emission of CO2 vs the reference oil combustion plant.

Design and Control of Modular Multilevel Converter for Voltage Sag Mitigation

Voltage sag in a power system is an unavoidable power quality issue, and it is also an urgent concern of sensitive industrial users. To ensure the power quality demand and economical operation of the power system, voltage sag management has always drawn great attention from researchers around the world. The latest research that realizes the power quality conditioning has used dynamic voltage restorers (DVRs), static VAR compensator (SVCs), adaptive neuro-fuzzy inference systems (ANFISs), and fuzzy logic controllers based on DVR to mitigate voltage sag. These devices, methods, and control strategies that have been recently used for voltage sag mitigation have some limitations, including high cost, increased complexity, and lower performance. This article proposes a novel, efficient, reliable, and cost-effective voltage sag mitigation scheme based on a modular multilevel converter (MMC) that ensures effective power delivery at nominal power under transient voltage conditions. The proposed method, the MMC, compensates for the energy loss caused by voltage sags using its internal energy storage of the submodules, and ensures reliable power delivery to the load distribution system. Furthermore, control strategies are developed for the MMC to control DC voltage, AC voltage, active power, and circulating current. Detailed system mathematical models of controllers are developed in the dual synchronous reference frame (DSRF). Validation of the results of back-to-back MMC for dynamic load distribution system is analyzed which proves the effectiveness of the proposed scheme for voltage sag mitigation.

Exergetic Port-Hamiltonian Systems: Navier-Stokes-Fourier Fluid

The Exergetic Port-Hamiltonian Systems modeling language combines a graphical syntax inspired by bond graphs with a port-Hamiltonian semantics akin to the GENERIC formalism. The syntax enables the modular and hierarchical specification of the composition pattern of lumped and distributed-parameter models. The semantics reflects the first and second law of thermodynamics as structural properties. Interconnected and hierarchically defined models of multiphysical thermodynamic systems can thus be expressed in a formal language accessible to humans and computers alike. We discuss a composed model of the Navier-Stokes-Fourier fluid on a fixed spatial domain as an example of an open distributed-parameter system. At the top level, the system comprises five subsystems which model kinetic energy storage, internal energy storage, thermal conduction, bulk viscosity, and shear viscosity.

Comparative Assessment of Multi-Port MMCs for High-Power Applications

Multi-port converters can interconnect different dc and ac systems while reducing semiconductor requirements and losses by eliminating redundant power conversion stages. Modular multilevel converter (MMC)-based multiport systems are well suited for application in mixed ac-dc grids containing high-voltage dc (HVDC) and medium-voltage dc (MVDC) systems. This paper conducts a detailed comparative assessment of multi-port dc-dc-ac MMCs for high power applications. Four representative topologies are chosen for study due to their contrasting internal power processing characteristics. Three different network scenarios are investigated that include HVDC and MVDC applications, covering several different power flow cases. The multi-port MMCs are compared in terms of losses, semiconductor effort, internal energy storage and magnetics requirements. The results are extensively discussed and general conclusions are summarized.

High-temperature molten-salt thermal energy storage and advanced-Ultra-supercritical power cycles

The work explores the opportunities offered by higher temperature heat transfer/heat storage fluids, and higher temperature power cycles, in higher concentration solar thermal power plants. The goal is to design a renewable energy plant able to supply fully dispatchable electricity to the grid at a cost, inclusive of dispatchability, better than using wind and solar photovoltaic with external energy storage by batteries. By increasing the receiver/hot tank temperature from 565-575 to 730°C, the efficiency of the thermal cycle increases by 30% vs. current plants working with conventional steam Rankine cycles (thermal efficiency η∼52% vs. present η∼40%). The proposed design permits 24/7 electricity production at the rated power of the turbine practically all year-round. In the hypothesis of no cost penalty for the use of a novel heat transfer and heat storage fluid, and of the higher pressure and temperature of the power cycle, that is a reasonable long term goal of an industrialized and mass-produced solution, the Levelized Cost of electricity may be improved from the 7.29-7.97 ¢/kWh of a current technology 100 MW design of annual average capacity factor 93-95.5%, to the 6.18-6.68 ¢/kWh of a 126 MW design of annual average capacity factor 94.9-97.7% of the novel technology. The work demonstrates the benefits of internal thermal energy storage by molten salt in supplying energy to renewable energy only grid, and the opportunity to further evolve the basic design now employed towards higher temperatures.