Energy Storage Process Research Articles

Nanoporous PANI/ZnO/VO2 ternary nanocomposite and its electrolyte for green supercapacitance

The green process of energy storage by utilizing the by-product obtained after the synthesis of PANI54.69 %: ZnO7.81 %: VO237.50 % (PZnV) nanocomposite by insitu single step method, as its electrolyte is demonstrated herein. This green approach yields 23 % improvement in the energy storage compared to that in the presence of 1 M H2SO4. The enhanced energy storage obtained for PZnV nanocomposite in the presence of acidified by-product are a specific capacitance (Cs) of 177.3 F g−1, a specific capacity (Q) of 212.7 C g−1, an energy density (E) of 35.46 W h kg−1 (comparable with E of lead acid batteries), and a power density (P) of 1.632 kW kg−1 at 1 A g−1. The PZnV exhibited an unique feature of increase in energy storage with increase in No. of CV cycles in the presence of 1 M H2SO4, and the maximum energy storage was achieved after 12,312 cycles with a Cs of 440.5 F g−1, a Q of 528.6 C g−1, an E of 88.10 W h kg−1 (comparable with E of Li-ion batteries), and a P of 2.154 kW kg−1. A good cyclic stability up to 16,812 cycles was achieved at 0.4 V s−1.

A multi-timescale optimization method for integrated energy systems with carbon capture and accounting

As the goal of “double carbon”, integrated energy systems aiming at the development of low-carbon economy are developing rapidly, and carbon capture and other emission reduction technologies are gradually gaining more extensive development space. For controlling carbon emissions and enhance the consumption of renewable energy. This work proposes to introduce carbon capture technology in the framework of integrated energy system and optimize the energy dispatching of integrated energy system in multiple time scales, and design a multi-time scale optimization model of integrated energy system with carbon capture. Based on the basic architecture of a low-carbon integrated energy system, this study analyzes the power characteristics of each unit of the integrated energy system, which consists of thermal power units, gas turbines, electric boilers, batteries, gas storage, heat storage, etc. By studying the energy conversion and storage processes of each unit, a power model of each unit of the integrated energy system is established. On this basis, the relationship between carbon emissions and unit output of thermal power units and gas turbines was studied, and a carbon emission model for the energy supply unit in the comprehensive energy system was established. At the same time, in order to solve the problem of carbon emission reduction under the day ahead scheduling plan of the integrated energy system, considering the emission reduction goals and system operation security factors, the study analyzed the economic model and carbon emission model of the integrated energy system, established the day ahead low-carbon scheduling model of the integrated energy system, and reasonably planned the output of each unit that can achieve the carbon emission reduction goals on the premise of meeting the balance of supply and demand. The innovation of the research method of this paper is that this paper establishes a multi time scale rolling optimization model under the emission reduction goal of the integrated energy system. Based on the day ahead scheduling scheme obtained in the day ahead low-carbon scheduling phase, the day ahead plan is first revised through 4 h rolling scheduling in the day; Then, with the goal of minimizing the adjustment amount, fine tune the unit output within 15 minutes to provide a daily output plan for subsequent low-carbon emission reduction targets. The outcomes indicate that in the practical application, the carbon emission of the optimized model in the peak hour 11:00 to 12:00 phase is 118 tons, which is 7 tons less than the 125 tons of the traditional model. In summary, it demonstrates that the studied multi-timescale optimization model of integrated energy system with carbon capture has good application. We have studied and analyzed the low-carbon implementation mechanism of coordinated cooperation in multiple time scales, and constructed a multi time scale rolling optimization model, laying a theoretical foundation for subsequent low-carbon scheduling research. This enables the system to formulate more accurate and reasonable scheduling plans, while improving the low-carbon performance and economic benefits of the system, providing reference for the low-carbon development of the power system.

The Pivotal Roles of Light and Ca‐Doping in Photothermocatalytic CO2 Reduction by Methane on Nanocomposites of Nickel Nanoparticles Loaded on Ca‐Doped Al2O3

CO2 and CH4 are greenhouse gases that can be converted into H2 and CO through light‐driven photothermocatalytic CO2 reduction with methane (CRM), which is a process of solar energy collection and storage. However, conventional catalysts require high light intensities (≥192.0 kW m−2) to obtain high fuel reaction rates and solar‐to‐fuel efficiency (η), and deactivate easily to coking at high temperature. Herein, a nanomaterial of Ni nanoparticles loaded on Ca‐doped Al2O3 (Ni/Ca–Al2O3) is synthesized. Ca doping improves the CO2 adsorption capacity of Ni/Ca–Al2O3. Under focused ultraviolet–visible–infrared illumination at low light intensity (80.8 kW m−2), Ni/Ca–Al2O3 obtains high production rates of H2 (, 76.85 mmol min−1 g−1) and CO (rCO, 90.90 mmol min−1 g−1), which are 1.9 and 1.3 times of those in the dark respectively, and exhibits a large η (30.3%) and good stability. The coking rate of Ni/Ca–Al2O3 is reduced by a factor of 25.8 compared to the reference catalyst with Ni nanoparticles loaded on Al2O3. The improvement of catalytic activity and anticoking properties stems from the photoactivation, which not only accelerates the CRM on Ni nanoparticles, but also enhances the oxidation of carbon species (produced on Ni nanoparticles) through strong adsorption of CO2 on Ca–Al2O3 at Ni/Ca–Al2O3 interface.

Hybrid Biomass Fast Pyrolysis Process and Solar Thermochemical Energy Storage System, Investigation and Process Development

Hybrid Biomass Fast Pyrolysis Process and Solar Thermochemical Energy Storage System, Investigation and Process Development

Utmost substance recovery and utilization for integrated technology of air separation unit and liquid air energy storage and its saving benefits

The integration of air separation units (ASUs) and liquid air energy storage (LAES) (ASU-LAES) can bring very good economic benefits based on their resource complementarity at the same low-temperature energy level. Two types of novel process flows are proposed in this paper for ASU-LAES. These flows can use the ASU to recover the maximum amount of refrigerated air from energy storage process to the front or back of the air compressor (i.e., pre- or post-machine recovery), so as to improve the energy efficiency and economic benefits. The pre-machine recovery process flow can achieve an electrical roundtrip efficiency of up to 76.38%. Although a lower refrigeration expansion ratio is used in the post-machine recovery process flow, it can form an air refrigeration cycle without passing through air compressor. Its exergy loss from expansion and compression is smaller, which maximizes liquid air storage. The electrical round-trip efficiency can reach up to 72.9%, and the larger storage scale increases its economic benefit compared to the pre-machine recovery. Based on the peak-to-valley price ratio of 3.4:1, the post-machine recovery process flow can save up to 13.23% of electricity cost compared to the conventional ASU. The dynamic payback period of the LAES is 2.27 years. Compared to ASU-LAES without recovery of refrigeration air, the electricity cost-saving ratio is improved by 134.9%, and the dynamic payback period of the LAES is shorten by 41.8%.

Decoupling electrolyte strategy for a high-voltage Na-ion hybrid capacitor based on NaFeO2 and activated carbon

Sodium iron dioxide (NaFeO2) with high specific capacity, has been widely used as a kind of electrode materials for Na-ion batteries. When NaFeO2 is used as the battery-type electrode for aqueous Na-ion hybrid capacitors, there are a lot of technical challenges to meet, especially the narrow voltage window limited by the thermodynamic decomposition of water. We propose a novel decoupling electrolyte strategy to suppress the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) on the NaFeO2 anode and the activated carbon (AC) cathode respectively, in order to expand the voltage window of the aqueous AC//NaFeO2 Na-ion hybrid capacitor. The alkaline anolyte (2 M NaOH) and the neutral catholyte (1 M Na2SO4) can be decoupled by the cation exchange membrane, which selectively allows the Na+ ions through the membrane to carry the electric currents in the charge/discharge process. The NaFeO2 sample with the stable crystal structure and oxygen vacancy defects, can provide a gravimetric specific capacitance of 101.1 F g−1 at 1 A g−1. Electrochemical kinetic analysis indicates that the capacitor-type behaviour is predominant in the electrochemical energy storage process of the AC//NaFeO2 Na-ion capacitor at the scan rates higher than 40 mV s−1. The AC//NaFeO2 Na-ion capacitor with the stable voltage window of 2 V, can provide an energy density of 12.6 Wh kg−1 at 1 kW kg−1. Due to its inhibiting effects on HER and OER, this decoupling electrolyte strategy holds great potential for constructing high-voltage aqueous energy storage devices.

Performance study of 660 MW coal-fired power plant coupled transcritical carbon dioxide energy storage cycle: Sensitivity and dynamic characteristic analysis

As the demand of modern society for electrical energy continues to rise, the combustion of fossil fuels has led to deterioration of global climate due to the emission of greenhouse gases. The introduction of zero-carbon goal has spurred rapid development of renewable energy. However, the intermittent nature of it has revealed the growing issue of insufficient capacity in existing power systems. To tackle this challenge and enhance the adaptability of power systems, improving the flexibility of coal-fired power plants has become a critical objective.In this work, a novel solution is proposed to address the lack of renewable energy accommodation capacity. It is the method of coupling transcritical carbon dioxide (T-CO2) energy storage cycle with the 660 MW coal-fired power plant (CFPP), using energy storage process to further reduce unit load and energy release process to increase it. The results show that, under the design operating parameters, CFPP achieves load increase and decrease rates of 70.32 MW/min and 35.04 MW/min, respectively. Moreover, at a thermal storage temperature of 353.1 K, T-CO2 energy storage cycle achieves a round-trip efficiency of 61.37% and an energy storage density of 0.989 kWh/m3. The results indicate that the combined system exhibits excellent performance, particularly under relatively lower thermal source temperature.

Automated analysis of surface facets: the example of cesium telluride

High-throughput screening combined with ab initio calculations is a powerful tool to explore technologically relevant materials characterized by complex configurational spaces. Despite the impressive developments achieved in this field in the last few years, most studies still focus on bulk materials, although the relevant processes for energy conversion, production, and storage occur on surfaces. Herein, we present an automatized computational scheme that is capable of calculating surface properties in inorganic crystals from first principles in a high-throughput fashion. After introducing the method and its implementation, we showcase its applicability, focusing on four polymorphs of Cs2Te, an established photocathode material for particle accelerators, considering slabs with low Miller indices and different terminations. This analysis gives insight into how the surface composition, accessible through the proposed high-throughput screening method, impacts the electronic properties and, ultimately, the photoemission performance. The developed scheme offers new opportunities for automated computational studies beyond bulk materials.

A Study on the Transient Response of Compressed Air Energy Storage in the Interaction between Gas Storage Chambers and Horseshoe-Shaped Tunnels in an Abandoned Coal Mine

This study focuses on the renovation and construction of compressed air energy storage chambers within abandoned coal mine roadways. The transient mechanical responses of underground gas storage chambers under a cycle are analyzed through thermal-solid coupling simulations. These simulations highlight changes in key parameters such as displacement, stress, and temperature within the chamber group during the loading and unloading processes of compressed air energy storage. It is found that within a cycle, the small circular chamber experiences the most significant deformation, with an average peak displacement of 0.24 mm, followed by the large circular chamber and horseshoe-shaped tunnels. The small circular chamber exhibits maximum tensile and compressive stresses. Therefore, special attention in engineering practice should be paid to the long-term safety and stability of small circular tunnels, and the stability of horseshoe-shaped tunnels should be also carefully considered. The findings from this study offer some insights for theoretical support and practical implementation in the planning, design, construction, and operation of high-pressure underground gas storage chambers for compressed air energy storage.

Optimization of the Porous Structure of Carbon Electrodes for Hybrid Supercapacitors with a Redox Electrolyte Based on Potassium Bromide

This work investigates the electrochemical behavior of hybrid supercapacitors with carbon-based electrodes of different porosity using 5M NaNO3 + 0.5M KBr electrolyte to optimize energy storage processes. Three types of carbon materials were synthesized: activated carbon from rice husk (RH) with a specific surface area of ~2300 m2/g and pore size < 1 nm, and templated carbons from magnesium citrate (MP-8) and glucose with SiO2 as a template (G7), having surface areas of 1976 and 1320 m2/g and pore sizes of 3.4 and 7 nm, respectively. The microporous structure of activated carbon (AC) obtained from RH shows limitations in the diffusion of electrolyte ions, which affects the charge-discharge kinetics. In contrast, the larger mesoporous structures of templated carbons promoted better adsorption and ion transport, significantly affecting the dynamics of redox reactions. The RH/MP-8 hybrid capacitor, combining high surface area and large pore size, demonstrated a 54% increase in specific capacitance, 128% increase in specific energy and 51% increase in energy efficiency at high current densities of 5 A/g, comparing to the symmetric RH/RH hybrid capacitor. This study highlights the critical importance of the relationship between electrode pore structure and electrolyte composition for optimizing supercapacitor performance, which provides valuable information for the development of efficient energy storage technologies.

Застосування алгоритмів штучного інтелекту в глобальній енергетичній індустрії

Cyber security, energy conservation, minimization of electricity losses, fault diagnosis, and re-newable energy sources were analyzed. Specific engineering problems have been defined for each field of energy, for which the use of artificial intelligence algorithms has been analyzed. Research has shown that AI algorithms can improve the processes of energy production, distri-bution, storage, consumption and trading.

Asymmetric Atomic Tin Catalysts with Tailored p‐Orbital Electron Structure for Ultra‐Efficient Oxygen Reduction

AbstractAtomically dispersed transition metal–nitrogen–carbon (M–N–C) catalysts guide by the d‐band center theory have been extensively studied for oxygen reduction reaction (ORR) in various energy conversion and storage processes. However, asymmetric p‐block metal single‐atom catalysts (SACs) toward ORR have rarely been reported, and the origin of their catalytic activity is still unclear. Here, an asymmetric N, O coordinated Sn SAC is developed as an efficient ORR electrocatalyst. Remarkably, the optimized Sn SAC (e.g., Sn–N/O–C) exhibit outstanding ORR performance with a half‐wave potential of 0.910 V in alkaline media, outperforming most state‐of‐the‐art ORR catalysts. More importantly, the Sn–N/O–C possesses a long‐term durability in both alkaline and acidic electrolytes. Besides, Zn–air batteries based on the Sn–N/O–C cathode also show a higher energy density (254 mW cm‐2) than that of their reported M–N–C counterparts. Theoretical calculations suggest that the asymmetric N, O coordinated atomic Sn sites have a stronger binding interaction with O2 and better charge transfer ability compared with the symmetric SnN4 sites, thereby facilitating the ORR process. This work provides a nitrogen‐, oxygen‐coordinated engineering strategy for the rational design of highly active and durable carbon‐based catalysts with atomic p‐block metal sites for ORR and beyond.

Research Progress on Vanadium Sulfide Anode Materials for Sodium and Potassium‐Ion Batteries

AbstractConsidering environmental changes and the demand for more sustainable energy sources, stricter requirements have been placed on electrode materials for sodium and potassium‐ion batteries, which are expected to provide higher energy and power density while being affordable and sustainable. Vanadium sulfide‐based materials have emerged as intriguing contenders for the next generation of anode materials due to their high theoretical capacity, abundant reserves, and cost‐effectiveness. Despite these advantages, challenges such as limited cycle life and restricted ion diffusion coefficients continue to impede their effective application in sodium and potassium‐ion batteries. To overcome the limitations associated with electrochemical performance and circumvent bottlenecks imposed by the inherent properties of materials at the bulk scale, this review comprehensively summarizes and analyzes the crystal structures, modification strategies, and energy storage processes of vanadium sulfide‐based electrode materials for sodium and potassium‐ion batteries. The objective is to guide the development of high‐performance vanadium‐based sulfide electrode materials with refined morphologies and/or structures, employing environmentally friendly and cost‐efficient methods. Finally, future perspectives and research suggestions for vanadium sulfide‐based materials are presented to propel practical applications forward.

Experimental analysis of packed bed cold energy storage in the liquid air energy storage system

Liquid air energy storage (LAES) is a large-scale energy storage technology with extensive demand and promising application prospects. The packed bed for cold energy storage (CES) is widely applied in LAES due to its safety and environmental friendliness. At present, most of the research on CES is theoretical analysis with symmetric cold energy transfer. Actually, the changes of the temperature field result in asymmetrical energy transfer in the energy storage and release processes, but there are few experimental studies on the dynamic characteristics and parameter influence mechanism. Therefore, a platform is established and experiments with different conditions are conducted. The dynamic characteristics of CES and the corresponding performance of LAES are analyzed. The results show that the thermocline develops until outlet temperature changes, leading to a decrease in the LAES efficiency. Under basic conditions, the energy and exergy efficiencies of CES are 90.3 % and 73.3 %. Selecting materials based on physical properties, reducing the flow rate and temperature range of the fluid can improve the packed bed performance. Furthermore, dynamic characteristics of CES gradually weaken until reaching a stable state after multi-cycle, with energy and exergy efficiencies decreasing by 2.5 % and 8.0 %. The decline in the LAES energy efficiency is 4.7 %.

Numerical investigation of latent heat storage unit with dual helical tube

The application of latent heat storage systems in waste heat recovery has become a promising solution for energy storage. This study proposes a configuration using dual helical tube, specifically designed for industrial waste heat recovery applications. This study investigates the thermal performance of a horizontal dual helical energy storage unit under natural gravity. It considers various parameters, including helical diameter, the number of helical turns, and eccentricity. When an eccentricity of 5 mm is used, the overall energy storage time is reduced by 30.86 %, and the energy storage density is at its highest (3.11 × 10−4 kW/cm2). Adjusting the outer helical tube to 9 turns produces the highest energy storage efficiency (0.9252). Additionally, the heat transfer characteristics during simultaneous energy storage and release processes have been studied. The results indicate that as the temperature difference or velocity ratio between the heat transfer fluids increases, the liquid fraction at steady state decreases. This decrease in liquid fraction requires a longer time to reach the steady state. When the outer helical tube is filled with the hot fluid and counter flow configuration is adopted, it achieves higher levels of absorption and release power at steady state. The influence of velocity on absorption and release power is more significant than that of temperature difference.

Study on photochemistry and component transport coupling processes of azobenzene molecular solar thermal system

Molecular solar thermal (MOST) system is a new technology to collect, transform and store solar energy. The mechanism of photochemical reaction and component transport of molecular photoswitches in the reactor is still unclear. In this paper, a simulated theoretical framework for energy conversion rate and energy storage efficiency of solar energy collection and conversion devices based on a molecular solar thermal system was presented. The mathematical model of the photochemical reaction studied was based on an azobenzene derivative, which acted as a molecular photoswitch that can store energy by the switch of molecular structures. The microscopic parameters of reactants were obtained by quantum mechanics calculation and applied to the macroscopic energy conversion analysis of reaction processes. The theoretical framework can predict the conversion and energy storage efficiency of photoisomerization reactions, and can be used for component transport analysis, energy conversion analysis and reaction rate contribution analysis in reactors. We focused on the influence of macroscopic factors, including the flow velocity, inlet reactants concentration and reactor size on the photoisomerization energy storage process. The results of the theoretical analysis were in good agreement with those of existing laboratory equipment. The relative error of the conversion rate is only 0.71% in the photostable state, and the maximum relative error of the conversion rate is 10.99% in the whole process. In addition, in the photochemical reaction, we introduced the concept of absorbance field for the absorbance attenuation caused by the absorption of photons in the medium, so that the local material conversion, absorbance and energy conversion of this type of photochemical reaction can be more clearly understood. This simulated theoretical framework allows the study of molecules in a macroscopic setting, thereby establishing a link between practical engineering and basic chemistry, and providing guidance for the design of molecular solar thermal systems in the future.

Experimental and numerical investigation on the charging and discharging process of a cold energy storage for space cooling of buildings

To address the current issue of the difficulty to use the hot outdoor environment during summer nights to provide coolness for phase change materials (PCM) and thus reduce building energy consumption in hot summer areas, a novel cold energy storage unit has been proposed. It replaces the hot outdoor environment with other free or cheap cold sources. An experimental setup is built to investigate the cold storage and release performance of the PCM storage unit. Later, the well-validated numerical model is conducted to further explore thermal performance of the PCM storage unit. The numerical result indicates that the cold storage process can be completed from 64.33 min to 96.56 min when the water inlet temperature varies from 10 °C to 16 °C. Further, during the cold release process, the PCM storage unit can reduce the temperature of the hot air by a maximum of about 8–12 °C when the air inlet temperature ranges from 32 °C to 38 °C. The cold release efficiency is varied between 81.65 % and 96.44 %. In conclusion, the findings provide a promising way for cold storage and space cooling of buildings in hot summer areas through the cold energy storage unit.

Magnesium calcites for CO2 capture and thermochemical energy storage using the calcium-looping process

In this study, a precipitation-based synthesis method has been employed to prepare magnesium calcites with the general formula Ca1-xMgxCO3, with the objective of use them in the calcium looping (CaL) process for CO2 capture (CaL-CCS) and thermochemical energy storage (CaL-CSP). The structure and microstructure of the samples have been characterized. It has been found by X-ray diffraction that the samples with a Ca:Mg molar ratio of 0.5:0.5 and 0.55:0.45 are phase pure, while the samples with molar ratios of 0.7:0.3 and 0.8:0.2 are composed by two phases with different stoichiometry. In addition, the sample prepared with calcium alone shows the aragonite phase. The microstructure of the magnesium-containing samples is composed of nanocrystals, which are aggregated in spherical particles whereas the aragonite sample presents a typical rod-like morphology.The multicycle tests carried out under CaL-CCS conditions show that an increase on the MgO content in the calcined samples results in a reduced value of effective conversion when compared to aragonite. On the other hand, under CaL-CSP conditions, the samples with the higher MgO content exhibit nearly stable effective conversion values around 0.5 after 20 cycles, which improve the results obtained for aragonite and those reported for natural dolomite tested under the same conditions.

Chitosan modified graphene oxide with MnO2 deposition for high energy density flexible supercapacitors

To obtain a flexible composite electrode material with excellent electrochemical performance, chitosan (CS)/graphene oxide (GO) composite pretreated from microwave hydrothermal is adopted as the carbon substrate, and MnO2 active material is uniformly deposited on their surface through anodic electrodeposition. In this composite system, CS penetrates into graphene sheets as small molecule units, forming NH-C=O groups with GO via dehydration condensation, which effectively inhibits the stacking of GO and improves the specific surface area, conductivity, as well as the wettability of the carbon support. MnO2 bonding with heteroatom N from CS enables high active material loadings and forms stable three-dimensional network structure, facilitating the enhanced electrochemical performance. Results indicate that increasing depositing MnO2 amount leads to more defective structures of the composite, which promotes their electrochemical performance when used as electrode material. The area specific capacitance of the optimal composite reaches 3553.74 mF/cm2 at 5 mA/cm2 in 1 M Na2SO4 electrolyte. Kinetic analysis shows the energy storage process is capacitance-dominated, with the redox reactions of MnO2 being the main contributor. The prepared asymmetric solid supercapacitor delivers an energy density high up to 0.585 mWh/cm2 at power density of 3000 mW/cm2, and their excellent flexibility makes them promising candidates as flexible sensor.

A novel cryogenic air separation unit with energy storage: Recovering waste heat and reusing storage media

The combination of the air separation unit and cryogenic energy storage enhances system efficiency; however, there are still significant irreversible losses in the energy conversion process and high investment costs. This paper explored the potential for deep integration of these two process and proposed a novel air separation with liquid nitrogen energy storage process recovering waste heat and reusing storage media process. The proposed process improved the liquefaction and power generation processes and recovered the compression heat for air purification processes. Taking an actual plant as a research case, the integrated system was simulated using Aspen Plus software. The round-trip efficiency, exergy efficiency, and power generation of the proposed process are 0.537, 0.722, and 10.52 MWh respectively, which are 6.2 %, 20.9 %, and 68.3 % higher than those of conventional process. By reusing storage nitrogen and recovering compression heat, the proposed process reduces the initial investment cost by half while achieving a dynamic payback period of 6 years with a levelized cost of electricity at $82.8/MWh. Furthermore, it is worth noting that media reuse operations have a greater impact on economy when off-peak electricity cost is low; whereas utilization of compression heat has a greater impact when off-peak electricity cost is high.