Free Energy Storage Research Articles

Von Neumann Entropy and Evolution

In this paper I outline a hypothesis where quantum information in the form of von Neumann entropy provides a universal driving force for increasing complexity of systems and for evolutionary processes. Interference between quantum states of interacting systems allows storage of free energy that can be used to overcome kinetic barriers and accelerate reactions. This informational work cycle is analogous to entanglement in quantum Carnot engines where energy is stored as phase or so-called phaseonium fuel. The von Neumann entropy subadditivity and Araki-Lieb inequality properties of combined states can lower effective entropy and favour routes to increasing complexity of systems. It is proposed that observed macroscopic evolutionary processes are the emergent manifestation of this microscopic informational drive to complexity.

Failure monitoring and classification from acoustic emission tests on impact-damaged hydrogen composite pressure vessels

Composite overwrapped pressure vessels (COPV) for hydrogen will play an important role in emission free mobility and energy storage. The DELFIN project (2018 – 2022) was set up with the goal of developing improved COPVs that are lighter, cheaper and more durable. A key aspect of this project was to conduct full-scale impact tests with different gas pressure levels that were used to evaluate the vessels’ crash performance and to verify numerical impact simulations. These tests were followed by controlled pressure experiments until the burst pressure was reached. The procedure was monitored with acoustic emission testing (AT) and subsequent computer tomography (CT). The residual COPV stability and the AT results are compared to different scenarios regarding the impact energies and impact angles. The event localization from AT shows a clear correlation of the emitted energy with the damaged areas. We classify the recorded signals into groups that can be related to the failure mechanism and compare those to the pressure evolution before failure of the COPV. All tests indicate that large impact energies lead to a significant reduction of the burst pressure of COPVs, whereas a higher internal pressure can have a stabilizing effect that reduces the damaging effect.

Ultrathin Electrode of Binder Free Energy Storage Device: Fabrication of MgO@RGO Nanocomposites through Hierarchical Synthesis

Ultrathin Electrode of Binder Free Energy Storage Device: Fabrication of MgO@RGO Nanocomposites through Hierarchical Synthesis

Sensing and Imaging Molecular Oxygen in Mammals with Spin Lattice Relaxation Electron Paramagnetic Resonance.

Molecular oxygen and its thermodynamic transformation drive nearly all life processes. Quantitative measurement and imaging of oxygen in living systems is of fundamental importance for the study of life processes and their aberrations-disease- many of which are affected by hypoxia, or low levels of oxygen. Cancer is among the disease processes profoundly affected by hypoxia. Electron paramagnetic resonance has been shown to provide remarkably accurate images of normal and cancerous tissue. In this review, we emphasize the reactivity of molecular oxygen particularly highlighting the metabolic processes of living systems to store free energy in the reactants. The history of hypoxic resistance of living systems to cytotoxic therapy, particularly radiation therapy is also reviewed. The measurement and imaging of molecular oxygen with pulse spin lattice relaxation (SLR) electron paramagnetic resonance (EPR) is reviewed briefly. This emphasizes the advantages of the spin lattice relaxation based measurement paradigm to reduce the sensitivity of the measurement to the presence of the oxygen sensing probe itself. The involvement of a novel small mammal external beam radiation delivery system is described. This enables an experimental paradigm based on control by radiation of the last resistant clonogen. This is much more specific for tumor cure than growth delay assays which primarily reflects control of tumor cells most sensitive to therapy.

High free volume polymers of intrinsic microporosity for efficient solar thermal fuels with enhanced energy storage capacity

Anchoring photoswitches on high free volume polymers is an emerging strategy to prepare high-performance solar thermal fuels (STFs), however, it still lacks a deep understanding about the relationship between free volume and energy storage performance. Herein, a bottom-to-up strategy was developed to prepare azobenzene-based STFs based on polymers of intrinsic microporosity (Azo-PIMs), in which free volumes could be changed by controlling the feeding ratio of co-monomers. Azo-PIM-1 and Azo-PIM-2 were prepared to have 7.41% and 19.07% azo grafting densities, respectively. The fractional free volume (FFV) and specific surface areas of Azo-PIM-1 are 0.17 and 552.8 m2 g−1, respectively, which are higher than that of Azo-PIM-2 (0.15 and 335.5 m2 g−1) due to the lower azo grafting density. The energy densities (EDg) of Azo-PIM-1 and Azo-PIM-2 in cis isomers are 13.39 J g−1 and 36.75 J g−1, and the corresponding storage enthalpy (ΔH) are 88.53 kJ mol−1 and 103. 35 kJ mol−1, respectively. Their ΔH are higher than that of the azo monomer of 83.76 kJ mol−1, demonstrating that PIMs as templates can efficiently increase the stored energy per azo moiety. Meanwhile, the higher ΔH of Azo-PIM-2 than that of Azo-PIM-1 indicates that the reduced free volume can enhance the energy storage capacity by prohibiting the rotation of azo photoisomerization. This work provides a basis for understanding the role of free volume on the energy storage performance of polymer-based STFs.

Ion Energization and Thermalization in Magnetic Reconnection Exhaust Region in the Solar Wind

Plasma energization and thermalization in magnetic reconnection is an important topic in astrophysical studies. We select two magnetic reconnection exhausts encountered by Solar Orbiter and analyze the associated ion heating in the kinetic regime. Both cases feature asymmetric plasma merging in the exhaust and anisotropic heating. For a quantitative investigation of the associated complex velocity-space structures, we adopt a three-dimensional Hermite representation of the proton velocity distribution function to produce the distribution of Hermite moments. We also derive the enstrophy and Hermite spectra to analyze the free energy conversion and transfer in phase space. We find a depletion of Hermite power at small m (corresponding to large-scale structures in velocity space) inside the reconnection exhaust region, concurrent with enhanced proton temperature and decreased enstrophy. Furthermore, the slopes of the 1D time-averaged parallel Hermite spectra are lower inside the exhaust and consistent with the effect of phase mixing that creates small fluctuations in velocity space. These fluctuations store free energy at higher m and are smoothed by weak collisionality, leading to irreversible thermalization. We also suggest that the perpendicular heating may happen via perpendicular phase mixing resulting from finite Larmor radius effects around the exhaust boundary.

Grid-Scale Virtual Energy Storage to Advance Renewable Energy Penetration

It is now widely recognized that energy storage enables increased integration of renewable resources. One of the uses of storage is to provide synthetic inertia, making up for some of the inertia lost from displaced conventional generation, thereby maintaining frequency stability. However, energy storage systems continue to be very expensive, and this motivates the development of innovative approaches to mitigate some of the challenges posed by renewable resources. This article presents a novel method called “grid-scale virtual energy storage” that harvests free energy storage from properties inherent to control of multiarea power systems, thereby increasing the amount of renewable generation that a system can tolerate before its frequency stability is compromised. The concept of virtual energy storage proposed here is based on the surplus of necessary energy that is required to restore the system frequency to within a safe range of the nominal frequency. In a dynamic sense, virtual energy storage is very responsive and is not limited by the operation time and capacity. Moreover, it can be exchanged easily among control areas and does not require installation and implementation expenses as it takes advantage of the existing diversity of area control errors in interconnected systems and employs an appropriate frequency control method. It also helps in reducing the reserve requirement, regulation capacity, transmission loading, and wear and tear on the power system by functioning as normal energy storage. In this article, the proposed new approach is explained mathematically, and its operation is analyzed using a mathematical model and simulation in order to validate its effectiveness.

Molecular dynamics inferred transfer learning models for finite‐strain hyperelasticity of monoclinic crystals: Sobolev training and validations against physical constraints

AbstractWe present a machine learning framework to train and validate neural networks to predict the anisotropic elastic response of a monoclinic organic molecular crystal known as ‐HMX in the geometrical nonlinear regime. A filtered molecular dynamic (MD) simulations database is used to train neural networks with a Sobolev norm that uses the stress measure and a reference configuration to deduce the elastic stored free energy functional. To improve the accuracy of the elasticity tangent predictions originating from the learned stored free energy, a transfer learning technique is used to introduce additional tangential constraints from the data while necessary conditions (e.g., strong ellipticity, crystallographic symmetry) for the correctness of the model are either introduced as additional physical constraints or incorporated in the validation tests. Assessment of the neural networks is based on (1) the accuracy with which they reproduce the bottom‐line constitutive responses predicted by MD, (2) the robustness of the models measured by detailed examination of their stability and uniqueness, and (3) the admissibility of the predicted responses with respect to mechanics principles in the finite‐deformation regime. We compare the training efficiency of the neural networks under different Sobolev constraints and assess the accuracy and robustness of the models against MD benchmarks for ‐HMX.

The value of in-reservoir energy storage for flexible dispatch of geothermal power

Geothermal systems making use of advanced drilling and well stimulation techniques have the potential to provide tens to hundreds of gigawatts of clean electricity generation in the United States by 2050. With near-zero variable costs, geothermal plants have traditionally been envisioned as providing “baseload” power, generating at their maximum rated output at all times. However, as variable renewable energy sources (VREs) see greater deployment in energy markets, baseload power is becoming increasingly less competitive relative to flexible, dispatchable generation and energy storage. Herein we conduct an analysis of the potential for future geothermal plants to provide both of these services, taking advantage of the natural properties of confined, engineered geothermal reservoirs to store energy in the form of accumulated, pressurized geofluid and provide flexible load-following generation. We develop a linear optimization model based on multi-physics reservoir simulations that captures the transient pressure and flow behaviors within a confined, engineered geothermal reservoir. We then optimize the investment decisions and hourly operations of a power plant exploiting such a reservoir against a set of historical and modeled future electricity price series. We find that operational flexibility and in-reservoir energy storage can significantly enhance the value of geothermal plants in markets with high VRE penetration, with energy value improvements of up to 60% relative to conventional baseload plants operating under identical conditions. Across a range of realistic subsurface and operational conditions, our modeling demonstrates that confined, engineered geothermal reservoirs can provide large and effectively free energy storage capacity, with round-trip storage efficiencies comparable to those of leading grid-scale energy storage technologies. Optimized operational strategies indicate that flexible geothermal plants can provide both short- and long-duration energy storage, prioritizing output during periods of high electricity prices. Sensitivity analysis assesses the variation in outcomes across a range of subsurface conditions and cost scenarios.

Load shifting potential assessment of building thermal storage performance for building design

As major energy consumers, buildings have great potential to alleviate the imbalance between renewable energy generation and consumer demand. A building thermal mass is a free energy storage object, and can provide a load shifting capacity. In this study, a parameter denoted the ‘effective thermal capacitance’ was proposed to characterise the building thermal mass, and a reduced-order RC model was established to predict the building cooling and heating loads. By using the particle swarm optimisation algorithm to identify the effective thermal capacitance values, the linear relationships between the effective thermal capacitance and building areas were summarised. The results show that, with an increase in the effective thermal capacitance, the hourly load and energy losses caused by load shifting strategies decrease. According to comparison results from applying the preheating and precooling strategies in four climatic zones of China, it is found that although the total load throughout the day is increased, the peak electricity consumption can be shifted without noticeable changes in the daily electric bill. During office hours, the preheating strategy reduces the heating load by approximately 12% in the severe cold and cold zones, whereas precooling reduced the cooling load by 20%–45% in all four climatic zones.

On the use of constrained reactive mixtures of solids to model finite deformation isothermal elastoplasticity and elastoplastic damage mechanics

This study presents a framework for plasticity and elastoplastic damage mechanics by treating materials as reactive solids whose internal composition evolves in response to applied loading. Using the framework of constrained reactive mixtures, plastic deformation is accounted for by allowing loaded bonds within the material to break and reform in a stressed state. Bonds which break and reform represent a new generation with a new reference configuration, which is time-invariant and provided by constitutive assumption. The constitutive relation for the reference configuration of each generation may depend on the selection of a suitable yield measure. The choice of this measure and the resulting plastic flow conditions are constrained by the Clausius–Duhem inequality. We show that this framework remains consistent with classical plasticity approaches and principles. Verification of this reactive plasticity framework, which is implemented in the open source FEBio finite element software (febio.org), is performed against standard 2D and 3D benchmark problems. Damage is incorporated into this reactive framework by allowing loaded bonds to break permanently according to a suitable damage measure, where broken bonds can no longer store free energy. Validation is also demonstrated against experimental data for problems involving plasticity and plastic damage. This study demonstrates that it is possible to formulate simple elastoplasticity and elastoplastic damage models within a consistent framework which uses measures of material mass composition as theoretically observable state variables. This theoretical frame can be expanded in scope to account for more complex behaviors.

Pencil graphite as electrode platform for free chlorine sensors and energy storage devices.

Multifunctional and low-cost electrode materials are desirable for the next-generation sensors and energy storage applications. This paper reports the use of pencil graphite as an electrode for dual applications that include the detection of free residual chlorine using electro-oxidation process and as an electrochemical energy storage cathode. The pencil graphite is transferred to cellulose paper by drawing ten times and applied for the detection of free residual chlorine, which shows a sensitivity of 27 μA mM-1 cm-2 with a limit of detection of 88.9 μM and linearity up to 7 mM. The sample matrix effect study for the commonly interfering ions such as NO3-, SO42-, CO32-, Cl-, HCO3- shows minimal impact on free residual chlorine detection. Pencil graphite then used after cyclic voltammogram treatment as a cathode in the aqueous Zn/Al-ion battery, showing an average discharge potential plateau of ~1.1 V, with a specific cathode capacity of ~54.1 mAh g-1 at a current of 55 mA g-1. It maintains ~95.8% of its initial efficiency after 100 cycles. Results obtained from the density functional theory calculation is consistent with the electro-oxidation process involved in the detection of free residual chlorine, as well as intercalation and de-intercalation behavior of Al3+ into the graphite layers of Zn/Al-ion battery. Therefore, pencil graphite due to its excellent electro-oxidation and conducting properties, can be successfully implemented as low cost, disposable and green material for both sensor and energy-storage applications.

The construction of relaxor perovskite Na0.5Bi0.5(Fe0.03Ti0.97)O3/Ba(Ti1-xSrx)O3 multilayer thin film and explorations on origin of the enhanced energy storage performance

Lead–free thin films with excellent high recoverable energy density (Wrec) and efficiency (η) are promising for application in miniature power devices. In this work, Na0.5Bi0.5(Ti,Fe)TiO3 (NBFT) and Ba(Ti,Sr)O3 (BST) systems are chosen for fabricating a series of 7NBFT/nBSxT (where 7, n and x mark the spin–coating cycles of NBFT, BSxT, and Sr2+ doping content, respectively) (n = 0, 2, 3, 4, and x = 0, 5, 10, 15, 20 mol. %) multilayer structures on Pt/Ti/SiO2/Si substrates via sol–gel process to explore the effects from key parameters of BSxT buffer layer on 7NBFT/nBSxT, including thickness (by modulating number of spin–coating cycles) and Sr2+ doping content. The highest Wrec ~ 56.5 J cm−3 and η ~ 66.6% are achieved for the relaxor 7NBFT/3BS0.15T multilayer, which are highly relevant to the enhanced homogeneous breakdown strength (EBD) of 2814 kV cm−1, large gap between the maximum and remnant polarization (Pmax–Pr) of 61.8 μC cm−2, originated from the highest αε and αεE0/εinit values as interpreted according to the Rayleigh Law. Besides, the existence of polar nano–regions (PNRs) contributes by lowering the energy for domain back–switching. These provide evidence that NBT–based multilayer thin film is of considerable potential for lead–free energy storage application.

Numerical Design Optimization of Short-Period HTS Staggered Array Undulators

Short period undulators are an essential component of a compact free electron laser (FEL) and medium energy storage rings for the production of hard X-rays. The use of ReBCO high temperature superconductors (HTS) in a staggered array undulator geometry is expected to yield a magnetic undulator flux density above 2 T for a 10 mm period and a 4 mm magnetic gap, thus substantially increasing the lasing performance of existing FEL and storage ring facilities. The optimization of the design for a staggered array undulator with FEM simulations and a critical analysis of its working principles are discussed in this paper. Specifically, the maximization of the undulator field and the minimization of the required HTS material are the two main objectives of this study, which is performed with realistic material parameters of commercially available bulks materials. Finally, the outcome of the applied optimization technique is discussed and the intrinsic limits of this undulator geometry are highlighted..

Thermodynamic analysis of a novel fossil‐fuel–free energy storage system with a trans‐critical carbon dioxide cycle and heat pump

Author(s): Hao, Y; He, Q; Liu, W; Pan, L; Oldenburg, CM | Abstract: This paper presents and analyzes a novel fossil-fuel–free trans-critical energy storage system that uses CO2 as the working fluid in a closed loop shuttled between two saline aquifers or caverns at different depths: one a low-pressure reservoir and the other a high-pressure reservoir. Thermal energy storage and a heat pump are adopted to eliminate the need for external natural gas for heating the CO2 entering the energy recovery turbines. We carefully analyze the energy storage and recovery processes to reveal the actual efficiency of the system. We also highlight thermodynamic and sensitivity analyses of the performance of this fossil-fuel–free trans-critical energy storage system based on a steady-state mathematical method. It is found that the fossil-fuel–free trans-critical CO2 energy storage system has good comprehensive thermodynamic performance. The exergy efficiency, round-trip efficiency, and energy storage efficiency are 67.89%, 66%, and 58.41%, and the energy generated of per unit storage volume is 2.12 kW·h/m3, and the main contribution to exergy destruction is the turbine reheater, from which we can quantify how performance can be improved. Moreover, with a higher energy storage and recovery pressure and lower pressure in the low-pressure reservoir, this novel system shows promising performance.

Ensemble Forecasting of Major Solar Flares with Short-, Mid-, and Long-term Active Region Properties

Abstract We apply an ensemble technique for major flare prediction by considering short-, mid-, and long-term active region (AR) properties and their relative contributions. For this, we consider magnetic parameters from Solar Dynamics Observatory/Helioseismic and Magnetic Imager and flare lists from Geostationary Operational Environmental Satellites. In this study, we simultaneously consider flaring rates during short- (1 day), mid- (several days), and long-term (several years) timeframes. In our model, the predicted rate is given by a weighted combination of the three rates such that the sum of their weights is 1. We calculate the Brier skill scores (BSSs) for investigating prediction performance and weights of these three terms to provide optimal results. The BSS (0.22) of the model with only long-term properties is higher than that with only short-term (0.07) or mid-term (0.08) properties. When short-/mid-term properties are additionally considered, the BSS is improved to 0.28/0.24. Our model has the best performance (BSS = 0.29) when all terms are considered, and their relative contributions to the short-, mid-, and long-term rates are 20%, 20%, and 60%, respectively. In addition, the model with three terms is more effective at predicting major flares in strong ARs. In view of the energy storage and release process, long-term magnetic properties may indicate the storage of magnetic free energy, while short- and mid-term flare history may reflect a recent trend of energy release process. Our results suggest that the performances of other existing flare models based on long-term properties should be improved by considering short- and/or mid-term flare history.

Conformation of a semiflexible filament in a quenched random potential.

Motivated by the observation of the storage of excess elastic free energy, prestress, in cross-linked semiflexible networks, we consider the problem of the conformational statistics of a single semiflexible polymer in a quenched random potential. The random potential, which represents the effect of cross-linking to other filaments, is assumed to have a finite correlation length ξ and mean strength V_{0}. We examine statistical distribution of curvature in filament with thermal persistence length ℓ_{P} and length L_{0} in the limit in which ℓ_{P}≫L_{0}. We compare our theoretical predictions to finite-element Brownian dynamics simulations. Finally, we comment on the validity of replica field techniques in addressing these questions.

PREDICTION OF IN-HOSPITAL MORTALITY AND LENGTH OF STAY IN ACUTE CORONARY SYNDROME PATIENTS USING MACHINE-LEARNING METHODS

BACKGROUND Nanomaterials offer greatly improved ionic transport and electronic conductivity compared with conventional battery and supercapacitor materials. They also enable the occupation of all intercalation sites available in the particle volume, leading to high specific capacities and fast ion diffusion. These features make nanomaterial-based electrodes able to tolerate high currents, offering a promising solution for high-energy and high-power energy storage. However, there are still many challenges associated with their use in energy storage technology and, with the exception of multiwall carbon-nanotube additives and carbon coatings on silicon particles in lithium-ion battery electrodes, the use of nanomaterials in commercial devices is very limited. After decades of development, a library of nanomaterials with versatile chemical compositions and shapes exists, ranging from oxides, chalcogenides, and carbides to carbon and elements forming alloys with lithium. This library includes various particle morphologies, such as zero-dimensional (0D) nanoparticles and quantum dots; 1D nanowires, nanotubes, and nanobelts; 2D nanoflakes and nanosheets; and 3D porous nanonetworks. Combined with lithium and beyond lithium ions, these chemically diverse nanoscale building blocks are available for creating energy storage solutions such as wearable and structural energy storage technology, which are not achievable with conventional materials. ADVANCES The success of nanomaterials in energy storage applications has manifold aspects. Nanostructuring is becoming key in controlling the electrochemical performance and exploiting various charge storage mechanisms, such as surface-based ion adsorption, pseudocapacitance, and diffusion-limited intercalation processes. The development of new high-performance materials, such as redox-active transition-metal carbides (MXenes) with conductivity exceeding that of carbons and other conventional electrode materials by at least an order of magnitude, open the door to the design of current collector–free and high-power next-generation energy storage devices. The combination of nanomaterials in hybrid architectures, such as carbon-silicon and carbon-sulfur, together with the development of versatile methods of nanostructuring, overcome challenges related to large volume change typical for alloying and conversion materials. These examples indicate that nanostructured materials and nanoarchitectured electrodes can provide solutions for designing and realizing high-energy, high-power, and long-lasting energy storage devices. OUTLOOK The limitations of nanomaterials in energy storage devices are related to their high surface area—which causes parasitic reactions with the electrolyte, especially during the first cycle, known as the first cycle irreversibility—as well as their agglomeration. Therefore, future strategies aim to develop smart assembly of nanomaterials into architectures with controlled geometry. Moreover, combining nanomaterials with complementary functionalities, such as high electronic conductivity of graphene or MXenes with high operating voltage and high redox activity of oxides, is necessary. Building sophisticated electrode architectures requires innovative manufacturing approaches, such as printing, knitting, spray deposition, and so on. Already-developed techniques such as 3D printing, roll-to-roll manufacturing, self-assembly from solutions, atomic layer deposition, and other advanced techniques should be used to manufacture devices from nanomaterials that cannot be made by conventional slurry-based methods. Such manufacturing approaches can also enable long-sought flexible, stretchable, wearable, and structural energy storage and harvesting solutions for Internet of Things and other disruptive technologies.

Comparing the thermodynamic potential of alternative liquid metal oxides for the storage of solar thermal energy

The relative potential of liquid multivalent metal oxides for the storage of thermal energy as sensible, latent and/or thermochemical storage energy in a liquid chemical looping thermal enerrgy storage (LCL-TES) is reported. This LCL-TES cycle comprises a reduction reactor, an oxidation reactor, two reservoirs for storing the hot and cold medium and a heat recovery unit. The materials were assessed on the basis of their melting temperature, Gibbs free energy, reaction temperature and thermal storage capacity. Ellingham diagrams were used to identify regimes with a potential for application in a LCL-TES, while phase diagrams were used to identify processes which combine sensible, latent and thermochemical heat storage. Based on these criteria, the oxide of CuO/Cu2O was found to have the greatest thermodynamic potential for use in a LCL-TES system with a total enthalpy of 404.67kJ/mol for thermal storage. However, the high temperature of ∼1200°C and corrosive nature of molten copper and its oxides will make this cycle challenging to implement. Lead, on the other hand has a lower total enthalpy of 250.09kJ/mol, but is molten at lower temperatures.

A lead free relaxation and high energy storage efficiency ceramics for energy storage applications

Abstract In the present work, ternary solid solution ceramics of the (1-x)SrTiO 3 -x(0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3 ) (STB100x) were designed and fabricated using a conventional solid-state sintering method. The phase structure, microstructure, dielectric property, relaxation property, ferroelectric property and energy storage property were systematically investigated. The addition of 0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3 (BT-BNT) could enhance the saturated polarization of the ceramics obviously. All the samples show a slim P-E hysteresis loop, and the sample with x = 0.3 exhibits a high energy storage density of 1.40 J/cm 3 and an energy storage efficiency more than 90%. These results indicate that the STB100x ceramics may be a promising lead free materials for high energy storage density capacitors.