Maximum Energy Storage Efficiency Research Articles

Performance prediction and determination of optimum optical property of the nanofluid for energy storage in direct absorption solar collectors

A direct absorption solar collector converts solar energy into thermal energy and stores it directly in the working fluid. Usually, a nanofluid is used as the working fluid. This work aims to study the behavior of the collector with wide variations of constructional and operating conditions, and then to arrive at the optimum mean extinction coefficients of the nanofluid for obtaining maximum energy storage efficiency. Some studies on these issues with limited scopes are available in the literature. A generalized way of choosing an optimized mean extinction coefficient of the nanofluid for applications in a direct absorption solar collector is not available elsewhere.The parametric behavior of a direct absorption solar collector is studied through a transient finite difference model that considers radiation and convection heat losses from the top surface and mirror reflection from the bottom. Node-wise transient energy equations are developed in terms of the mean extinction coefficient of the working fluid. The optimized mean extinction coefficient points, corresponding to the maximum energy storage efficiency under one sun incident illumination, are identified over a large number of parametric computations. These data show that the optimum mean extinction coefficient decreases with fluid height and illumination time. Correlations for optimum mean extinction coefficient as functions of fluid height and illumination time are derived through regression analyses over the maxima points. A simplified time-averaged correlation solely as a function of fluid height is also presented. In addition, an average optical thickness, a product of the fluid height and optimum mean extinction coefficient, of 2.35 is recommended while using a fluid height between 20 and 80 mm. It is expected that this work would enable one not only to understand the parametric behavior of the collector but also to design it optimally.

Fast polarization switching capability mediated by oxygen deficiency in Co-substituted SrFeO3-δ perovskites

In this study, a series of eco-friendly, oxygen-deficient SrFe1-xCoxO3-δ (x = 0.00, 0.33, 0.66, and 1.00) perovskite samples was prepared via a sol–gel-based auto-combustion route. Analysis of X-ray diffraction data confirmed the synthesis of the single-phase cubic perovskite structure for x = 0.00 to x = 0.66, whereas SrCoO3-δ had a single-phase tetragonal structure. The lattice constants decreased as the Co contents increased due to the smaller ionic radii of Co4+ ions. Field emission scanning electron microscopy images showed that the grain size decreased initially, but the size increased with the increase in Co substitution above x = 0.33. Ferroelectric behavior was analyzed under an electric field of 50 V/cm with a frequency of 50 Hz. The unsaturated polarization–electric field loops for SrFeO3-δ indicated relaxor-type ferroelectric behavior. The maximum polarization (Pmax) and remanent polarization (Pr) both decreased as the Co contents increased. The maximum recoverable energy density was recorded for SrFeO3-δ. However, the maximum energy storage efficiency of 66% was obtained for the SrFe0.67Co0.33O3 sample. These findings demonstrate that members of the SrFe1-xCoxO3-δ series, particularly with x = 0.33, could be potential candidates for use in energy and data storage devices, mainly due to the high value of Pmax − Pr, superior storage efficiency, and rapid polarization switching ability.

Synergistic effects of Zn B-site substitution in lead-free Ba0.95Ca0.05Ti0.92Sn0.08O3 ferroelectric ceramics for enhancing piezoelectric properties in energy harvesting applications

In this study, lead-free (Ba0.95Ca0.05)(Ti0.92Sn0.08)O3 (BCTS) and (Ba0.95Ca0.05)(Ti0.912Sn0.08Zn0.008)O3 (BCTS-Zn) ceramics with large piezoelectric properties were prepared via the conventional solid-state reaction. The effect of Zn B-site substitution on the structural, dielectric, ferroelectric, energy storage, electrocaloric and piezoelectric properties of BCTS ceramics were systematically investigated. X ray diffraction analysis and Raman spectroscopy of BCTS and BCTS-Zn ceramics confirm the formation of pure phase structure with the coexistence of orthorhombic, tetragonal and pseudo cubic phases at room temperature. The introduction of Zn into BCTS lattice resulted in a denser microstructure with larger average grain size which contributed in the enhancement of the dielectric constant maximum by ⁓35%. Furthermore, the substitution of Ti4+ with a small amount of Zn2+ (0.008) induced a shift in TR-O, TO-T and TT-C transitions towards higher temperatures in addition to an increase in the diffused phase transition character. Moreover, with Zn substitution, an amelioration in the maximum energy storage efficiency is observed from ⁓83% in BCTS ceramic to ⁓88% in BCTS-Zn ceramic. The electrocaloric properties were investigated using the direct and indirect methods. The highest value of the electrocaloric temperature change ΔT = 0.361 K at 319 K was calculated for BCTS ceramic using Maxwell approach with a relatively low electric field of 17.55 kV/cm. For BCTS-Zn ceramic, the enhancement of the piezoelectric properties (d33 = 420 pC/N, g33 = 23.02 mV/mN, FoM = 9.66 pm2/N) is attributed to the synergistic effect of the (O-PC-T) multiphase coexistence, large average grain size and high density of the ceramic. This study reveals that B site Zn substitution in BCTS lattice is an effective approach to improve the piezoelectric properties of the ceramic for energy harvesting applications.

Thermodynamic, economic and environmental investigations of a novel solar heat enhancing compressed air energy storage hybrid system and its energy release strategies

In this paper, a novel solar heat enhancing compressed air energy storage hybrid system is proposed, which mainly consist of three subsections: wind power sub-system, compressed air energy storage sub-system, and solar heat enhancing sub-system. The hybrid system driven by the excess electricity of wind power sub-system storages compressed air in an air storage tank and reserves compression heat with thermal storage medium from cylinder liner heat exchangers and inter-stage heat exchangers, and improves the thermal storage medium to a higher temperature by solar heat enhancing sub-system for a greater power output of the system. Three energy release strategies of the systems are proposed. And the thermodynamic performance of three release strategies is compared. The results show that Strategy 2 has a largest energy storage efficiency and energy storage density, which is 56.52%, 19.8 MJ/m3, respectively. In addition, energy, economic and environmental analyses are conducted. The payback period of system is 3.5 years. Compared with systems which are not combined with solar energy, the energy conversion efficiency of the system designed in this paper enhances by 25%, and the carbon emission reduces approximately by 42%. The payback period of system is also reduced. The influence of important parameters on system performance is explored using parametric analysis. The system can achieve a maximum energy storage efficiency when wind speed is 11 m/s. Meanwhile, energy storage efficiency and energy storage density all improve with the increase in environment pressure and solar irradiance, whereas these characteristics show divergent trends as the ambient temperature changes.

Type II absorption thermal battery for temperature upgrading: Energy storage heat transformer

Low grade and intermittence are the two main obstacles hindering the utilization of renewable/waste energy. The conventional thermal battery can address the intermittence issue by matching the timing between energy supply and energy demand, but it can never address the low-grade issue. To address this problem, a novel type II absorption thermal battery for temperature upgrading is proposed, which combines the functions of energy storage and heat transforming. Dynamic simulation is conducted based on an experimentally validated model to investigate the transient characteristics and cycle performance. Both the energy storage performance (i.e., energy storage efficiency and density) and the heat transformer ability (i.e., temperature lift) are comparatively analyzed. The maximum energy storage efficiency is between 0.42 and 0.44, while the maximum energy storage density varies from 195.6 kWh/m3 to 292.7 kWh/m3, with charging temperatures of 70–90 °C, temperature lifts of 10–55 °C, and a cooling water temperature of 32 °C. There is a trade-off between the energy storage performance and the heat transformer ability. Besides, a higher charging temperature or a lower cooling water temperature can enhance the energy storage performance and the heat transformer ability. Compared to the existing thermal batteries, the novel type II absorption thermal battery shows a unique advantage of temperature upgrading whilst yielding a high energy storage density and a high exergy efficiency. This study aims to provide theoretical references and suggestions for the development of the type II absorption thermal battery.

On the rational development of advanced thermochemical thermal batteries for short-term and long-term energy storage

Thermal energy storage is an important means for achieving carbon neutrality. Absorption thermal battery is a promising solution for renewable energy utilization due to its excellent energy storage performance and operational flexibility. This study conducts comparative investigations among different absorption thermal battery cycles from a multi-criteria perspective, including energy storage efficiency, energy storage density, exergy efficiency, charging temperature, and initial cost. Except for the existing cycles (i.e., basic cycle, compression-assisted cycle, double-stage cycle, and double-effect cycle), a novel double-effect compression-assisted cycle is also included to cover a wider range of design options. The effects of charging/discharging/cooling temperatures on the storage performance are analyzed in three scenarios, i.e., short-term cold storage, short-term heat storage, and long-term heat storage. Results indicate that the compression-assisted cycle and the double-stage cycle can improve the energy storage density and lower the charging temperatures (e.g., below 70 °C); the double-effect cycle can enhance the energy storage efficiency; the double-effect compression-assisted cycle can achieve improvements in energy storage efficiency and density simultaneously, with a maximum energy storage efficiency above 1.30 and energy storage density over 300 kWh/m3, and bridge the temperature gap (i.e., 100 °C–140 °C) between the single-effect and double-effect cycles. The maximum energy storage efficiency, energy storage density, and exergy efficiency are 1.53, 365.4 kWh/m3, and 0.61, achieved by the double-effect cycle, the compression-assisted cycle, and the basic cycle, respectively. This work aims to facilitate the rational development of absorption thermal battery cycles for high-density and high-efficiency thermal energy storage towards carbon neutrality.

High Energy Storage Efficiency and Electrocaloric Effect in Pb-Free Ba0.85Ca0.15Hf0.10Ti0.90O3 Ceramics for Sustainable Green Energy Applications

In this work, Pb-free Ba0.85Ca0.15Hf0.10Ti0.90O3 (BCHT) ferroelectric ceramic was synthesized via the sol-gel method and its structural, dielectric, ferroelectric, electrocaloric, and energy storage characteristics have been investigated under a low electric field of 20 kV/cm. The Rietveld refinement of XRD patterns shows good agreement with the co-existence of two phases tetragonal (P4mm) and cubic (Pm3m), with each phase contribution of 58 and 42% respectively. A volumetric porosity of around 11.5% is observed. The electrocaloric temperature change ΔT and entropy change ΔS have been estimated by an indirect approach using Maxwell relations. The room temperature value of – ΔS and ΔT are 0.207 J/Kg.K and 0.157 K respectively and a wide temperature span of 50K was observed. The room temperature observed enhanced total energy density, recoverable energy density, and energy storage efficiency were 84.43 mJ/cm3, 64.38 mJ/cm3, and 76.25 % respectively. The maximum energy storage efficiency of 85.03% was observed at 80oC. The Pb-free BCHT ceramic is a promising candidate for eco-friendly cooling and energy storage technology.

Thermodynamic and Economic Assessment on the Supercritical Compressed Carbon Dioxide Energy Storage System coupled with Solar Thermal Storage

In recent years, renewable energy, particularly solar energy and wind energy, has demonstrated robust growth worldwide. However, the intermittent nature of these energy sources causes significant challenges for the security and reliability of grid, which limits the penetration growth in power market. To enable a higher penetration of renewable energy sources and satisfy the demand for peak shaving and valley filling of the grid, one possibility is to couple them with energy storage systems. In this study, two supercritical compressed carbon dioxide energy storage systems coupled with concentrating solar thermal storage are proposed. One is a simple compression cycle, and the other is a split compression cycle. Both thermodynamic and economic performance have been investigated numerically. The effects of energy storage pressure, heating temperature, thermal oil mass flow rate and split ratio are discussed. The results indicate that under the designed condition, there exists a maximum energy storage efficiency for the simple cycle when the heating temperature is lower than 538.15K. Continuing to increase heating temperature, the efficiency first increases from 64% to 73.9% rapidly as the total pressure ratio rises from 3 to 5. However, the improvement of it will be limited after the pressure ratio exceeds 5. Besides, if the thermal oil mass flow rate rises, the efficiency also has a maximum value, which appears between 150kg/s and 160kg/s. Finally, for the split cycle, there exists an optimal value. And the optimal condition can promote the Dynamic Payback Period and Levelized Cost of Energy to fall about 2 years and 6.1% compared to the simple cycle.

A Real-Time-Link-Adaptive Operation Scheme for Maximum Energy Storage Efficiency in Resonant CM Wireless Power Receivers

The development, analysis, and experimental validation of an energy storage algorithmic scheme for performance optimization of resonant inductive power receivers are presented. Motivated by the crucial role of efficient energy storage in the next generation of brain-implantable devices, we introduce an energy management strategy in the design of wireless powering links, in which, the key performance measure is the energy stored during a limited time interval rather than the average energy delivered to the load. The presented strategy is proven analytically to yield the theoretically-maximum energy storage efficiency over a pre-determined period of time. Additionally, thanks to the algorithm's closed-form solution, the optimization can be done in real time, offering the potential for a solution that is adaptive to any variations in physical (e.g., coil separation, Rx rotation, etc.) and/or electrical (e.g., Q-factor, media conductivity, etc.) properties of the link, conditional to a low-power circuit implementation for its evaluation. The efficacy and precision of the solution obtained from the presented analytical model is confirmed with CAD-based simulation results, and later validated using experimental measurements. Our experimental results for two links with different characteristics (resonance frequency, coils size and separation, etc.) show a 52.5% and 67.5% improvement in overall energy storage efficiency compared to the standard CM receiver design in which resonance-to-charging switching is performed when the receiver's LC tank energy accumulation starts to saturate. This is while the presented method does not require any calibration and is designed to be employed by any generic current-mode receiver.

Modulation in polymer properties in PVDF/BCZT composites with ceramic content and their energy density capabilities

AbstractThe lead‐free 0.5((Ba0.7Ca0.3)TiO3)‐0.5(Ba(Zr0.2Ti0.8))O3(BCZT) piezoceramics were synthesized using sol‐gel method. The Rietveld analysis of X‐ray diffraction (XRD) data and differential scanning calorimetry (DSC) studies of as‐synthesized BCZT powder suggests the co‐existence of ferroelectric orthorhombic (O) and tetragonal (T) phases at room temperature (RT). The value of curie temperature (TT‐C) as depicted from DSC and dielectric studies was found to be ≈ 110°C. The BCZT ceramic particles were dispersed in the polyvinylidene fluoride (PVDF) matrix, an electroactive polymer with great ferro/piezoelectric response in its distinct β and γ phases, to form ferroelectric ceramic‐polymer composites for their applications in flexible energy storage capacitors. The present work reports the Fourier‐transform infrared spectroscopy (FTIR), XRD, dielectric, ferroelectric, and energy density properties of PVDF/BCZT composite films having different wt% of BCZT content fabricated by the solution‐cast technique. The FTIR and XRD studies depict the γ‐PVDF and pure BCZT phases in composite films. The dielectric studies estimated the relative permittivity (εr) of a composite film with 50 wt% of BCZT content to be ≈ 31 (at 120 Hz) which was about three times as compared with that of pure PVDF. The dielectric loss (tan δ) was maximum ≈ 0.15 (at 120 Hz) for 50 wt% BCZT composition. The ferroelectric studies and energy storage calculations showed that the value of remnant polarization (Pr), coercive field (Ec) and energy storage density (W) attain the maximum value of 0.63 μC/cm2, 21.20 kV/cm, and 70.46 mJ/cm3, respectively for the film sample having 40 wt% BCZT content. The maximum energy storage efficiency, η (%) is calculated to be ≈ 60 for 50 wt% BCZT composition. The results indicated that the incorporation of BCZT particles in the PVDF matrix improved the overall polarization (polar and interfacial) which enhance the electric properties of composite films. The ferroelectric studies with temperature revealed the PVDF/BCZT composition‐dependent polymer or ceramic dominance in the behavior of composite films. With the maximum value of relative permittivity (εr) and energy storage efficiency (η), the PVDF/BCZT composition with 50 wt% of BCZT content has been optimized for applications in flexible energy storage capacitors.

Energy storage efficiency optimization of methane reforming with CO2 reactors for solar thermochemical energy storage☆

In CO2 reforming of methane solar thermochemical energy storage, much research has been conducted to enhance the thermochemical performance of the reactor. However, there has been little research conducted to investigate the effects of dimensions on the reactor thermochemical performance. Moreover, little innovation has occurred on optimizing reactor dimensions and operating conditions simultaneously. In this paper, a model has been developed to simulate CO2 reforming of methane reaction in a tubular packed reactor. By comparing with experimental and simulation data from another publication, the model is validated to be more accurate. A parametric study has been performed to investigate the effects of dimensions and operating conditions on the reactor thermochemical conversion and energy storage efficiency. The result shows that there is a trade-off between achieving a higher energy storage efficiency and decreasing the conversion by having smaller reactor with larger gas flow rate. An optimization study of all the design parameters, based on the reaction model coupled with a multistart optimization algorithm, is performed to find the maximum energy storage efficiency for a fixed required conversion. Without sacrificing the conversion, an energy storage efficiency of 0.77, which is 10% higher than the highest established experimental data, is obtained through optimization. The study provides a baseline for further thermodynamic analysis of the entire system.

Effects of BiScO3 Doping on the Phase Structure, Ferroelectric, Energy Storage, Strain, and Dielectric Properties of Bi0.5Na0.5TiO3 Ceramics

In this study, (1–x)Bi0.5Na0.5TiO3– xBiScO3 (BNT–xBS) ceramics were synthesized via conventional solidstate reaction sintering. The effects of the BiScO3 content on the surface microstructure, energy storage, strain, and dielectric properties of BNT–xBS ceramics were systemically investigated. Results indicated that the phase structure of BNT–xBS ceramics transformed from the rhombohedral phase into the pseudo-cubic phase. As the increasing BiScO3 content, the average grain size decreased. BiScO3 destroyed the long-range ordered ferroelectric phase, enhancing relaxor behavior. Energy storage density initially increased and then decreased, reaching a maximum of 0.17 J/cm3 at x = 0.1. In addition, the maximum energy storage efficiency was 59% at x = 0.2. The BiScO3 content significantly affected the electrical properties of BNT– xBS ceramics.

Effect of SnO2 doping on electric field-induced antiferroelectric-to-ferroelectric phase transition of Pb(Yb1/2Nb1/2)0.98Sn0.02O3 ceramics

Pb(Yb1/2Nb1/2)0.98Sn0.02O3-xSnO2 (PYNS-xSn) antiferroelectric ceramics with high Curie temperatures (Tc), were prepared by the solid state reaction method. The double P-E hysteresis loops of PYNS-xSn ceramics (0.02 ≤ x ≤ 0.08) were observed at the temperatures higher than 180 °C, confirming its antiferroelectric nature. The electric fields (EAFE-FE) inducing the transition from antiferroelectric (AFE) phase to ferroelectric (FE) phase were decreased to be lower than the average dielectric breakdown strength (Eb) by SnO2 doping. The decrease of EAFE-FE can be attributed to the larger lattice constant ratio a/b and the lower B-site cation ordering. The energy storage performance is enhanced effectively with the decrease of EAFE-FE. The maximum energy storage efficiency (67.9%) and recoverable energy storage density (2.38 J/cm3) were obtained in PYNS-0.06Sn ceramics at the temperature of 180 °C. The results indicated that SnO2-doped PYNS antiferroelectric ceramics could be potential candidates for energy storage applications at elevated temperatures.

Assessment of strong relaxation on BaTiO3 modified by Mn2+ and Pr3+, K+ at A− and B− site respectively

Nanocrystalline Ba1−xMnxTi1−xPrxKxO3; x = 0.1 was synthesized using precursor solution decomposition method. The material exhibited relaxor behavior both in dielectric and impedance analysis. The grain boundary showed high dc conductivity indicated doubly ionized oxygen vacancy which was also supported from SEM analysis. P-E hysteresis loop supported ferroelectric characteristics of the material with maximum energy storage efficiency 57% at 200 V.

Bi0.5Na0.5TiO3-BaTiO3-K0.5Na0.5NbO3:ZnO relaxor ferroelectric composites with high breakdown electric field and large energy storage properties

0.82[0.94Bi0.5Na0.5TiO3-0.06BaTiO3]-0.18K0.5Na0.5NbO3:xZnO (BNT-BT-KNN:xZnO, x = 0-0.40) relaxor composites were prepared and their electrical properties were investigated. The breakdown electric field increases with increasing ZnO content. For x = 0 and x = 0.40 samples, the maximum recoverable energy storage density is 0.74 J/cm3 and 1.03 J/cm3 while the maximum energy storage efficiency is 86.7% and 72.7% under the electric field of 9.0 kV/mm and 14.0 kV/mm, respectively. The recoverable energy storage density and efficiency of the composite vary less than 2.5% from 25 °C to 125 °C, which indicates temperature-insensitive energy storage performance. These results are discussed based on the ZnO-enhanced bulk resistivity and the ZnO-induced local electric field which suppresses the evolution of polar nanoregions.

Energy storage efficiency analyses of CO2 reforming of methane in metal foam solar thermochemical reactor

Solar driven CO2 reforming of methane can store extra 20% concentrated solar energy to chemically bonded energy. With the aim to evaluate key operational parameters on energy storage efficiency, a finite volume method (FVM) coupled with thermochemical kinetics was developed to analyze the solar driven CO2 methane reforming performance in a metallic foam thermochemical reactor. The LH kinetic model of CO2 reforming of methane was compiled by user defined functions (UDFs) to exactly predict the temperature distribution and mole fractions of gas species. The numerical results were validated with experimental results which were tested in Niigata University to guarantee the accuracy of the developed model. Effects of gas mixture inlet velocity, porosity of metal foam reactor, CH4/CO2 ratio and heat flux distribution on energy storage efficiency were analyzed for providing theoretical guideline to the application of solar driven CO2 methane reforming. The numerical results indicated that maximum energy storage efficiency of CO2 reforming of methane was found when the CH4/CO2 ratio is 0.67.

Charging System Optimization of Triboelectric Nanogenerator for Water Wave Energy Harvesting and Storage.

Ocean waves are one of the most promising renewable energy sources for large-scope applications due to the abundant water resources on the earth. Triboelectric nanogenerator (TENG) technology could provide a new strategy for water wave energy harvesting. In this work, we investigated the charging characteristics of utilizing a wavy-structured TENG to charge a capacitor under direct water wave impact and under enclosed ball collision, by combination of theoretical calculations and experimental studies. The analytical equations of the charging characteristics were theoretically derived for the two cases, and they were calculated for various load capacitances, cycle numbers, and structural parameters such as compression deformation depth and ball size or mass. Under the direct water wave impact, the stored energy and maximum energy storage efficiency were found to be controlled by deformation depth, while the stored energy and maximum efficiency can be optimized by the ball size under the enclosed ball collision. Finally, the theoretical results were well verified by the experimental tests. The present work could provide strategies for improving the charging performance of TENGs toward effective water wave energy harvesting and storage.

Enhanced Electrical Energy Storage Density in Mechanical Confined Antiferroelectric Ceramic

This article reports the effect of compressive stresses on electrical energy storage density of Pb0.99Nb0.02 [(Zr0.57Sn0.43)0.94Ti0.06]0.98O3 (PNZST) antiferroelectric bulk ceramics. The increased energy density was obtained under uniaxial and radial compressive stresses. These have been explained in terms of dipolar reorientation associated with high field stimulus of ferroelectric materials. The polarization/depolarization and increment in energy density are found to be dependent on the crystallographic orientation, applied electric field and direction of stress. The results indicate that stress induced phase suppression can increase the storage density by ∼23% (75 MPa) and 17% (90 MPa) for uniaxial and radial compressive stresses, respectively. Maximum energy storage efficiency of ∼65% (75 MPa) and 85% (200 MPa) are observed in uniaxial and radial cases, respectively.

Proton Electroinsertion in Self-Assembled Materials for Neutralization Pseudocapacitors

We propose novel pseudocapacitors that can store energy related to the partial entropy change associated with proton concentration variations following neutralization reactions. In this situation, it is possible to obtain electrochemical energy after the complete charge/discharge cycle conducted in electrolytic solutions with different proton concentrations. To this end, we prepared modified electrodes from phosphomolybdic acid (PMA), poly(3,4-ethylenedioxythiophene/poly(styrenesulfonate) (PEDOT-PSS), and polyallylamine (PAH) by the layer-by-layer (LbL) method and investigated their electrochemical behavior, aiming to use them in these neutralization pseudocapacitors. We analyzed the potentiodynamic profile of the current density at several scan rates, to evaluate the reversibility of the proton electroinsertion process, which is crucial to maximum energy storage efficiency. On the basis of the proposed reaction mechanism and by using frequency-domain measurements and models, we determined rate constants at different potentials. Our results demonstrated that the conducting polymer affects the self-assembled matrixes, ensuring that energy storage is high (22.5 kJ mol(-1)). The process involved neutralization of a hydrochloric acid solution from pH = 1 to pH = 6, which corresponds to 40% of the neutralization enthalpy.

Efficiency of sequential resonance compression of radio pulses

A study is made of the efficiency of forming high-power wide-band and ultrawide-band radio pulses by a sequence of resonance compression steps. An analysis is made of the compression of radio pulses with a rectangular envelope in a chain consisting of two or three compressors, and also in a chain where the output signal from the first stage has an exponential trailing edge and the other stages have rectangular envelopes. The maximum energy storage efficiency is determined for a cavity excited by a signal with an exponential trailing edge.