Development and technology status of energy storage in depleted gas reservoirs

Utilizing energy storage in depleted oil and gas reservoirs can improve productivity while reducing power costs and is one of the best ways to achieve synergistic development of"Carbon Peak–Carbon Neutral"and"Underground Resource Utiliza-tion".Starting from the development of Compressed Air Energy Storage(CAES)technology,the site selection of CAES in depleted gas and oil reservoirs,the evolution mechanism of reservoir dynamic sealing,and the high-flow CAES and injection technology are summarized.It focuses on analyzing the characteristics,key equipment,reservoir construction,application scenarios and cost analysis of CAES projects,and sorting out the technical key points and existing difficulties.The devel-opment trend of CAES technology is proposed,and the future development path is scrutinized to provide reference for the research of CAES projects in depleted oil and gas reservoirs.

Highly Active Interfacial Sites in SFT-SnO_(2) Heterojunction Electrolyte for Enhanced Fuel Cell Performance via Engineered Energy Bands:Envisioned Theoretically and Experimentally

Extending the ionic conductivity is the pre-requisite of electrolytes in fuel cell technology for high-electrochemical performance.In this regard,the introduction of semiconductor-oxide materials and the approach of heterostructure formation by modulating energy bands to enhance ionic conduction acting as an electrolyte in fuel cell-device.Semiconductor(n-type;SnO_(2))plays a key role by introducing into p-type SrFe_(0.2)Ti_(0.8)O_(3-δ)(SFT)semiconductor perovskite materials to construct p-n heterojunction for high ionic conductivity.Therefore,two different composites of SFT and SnO_(2)are constructed by gluing p-and n-type SFT-SnO_(2),where the optimal composition of SFT-SnO_(2)(6∶4)heterostructure electrolyte-based fuel cell achieved excellent ionic conductivity 0.24 S cm^(-1)with power-output of 1004 mW cm^(-2)and high OCV 1.12 V at a low operational temperature of 500℃.The high power-output and significant ionic conductivity with durable operation of 54 h are accredited to SFT-SnO_(2)heterojunction formation including interfacial conduction assisted by a built-in electric field in fuel cell device.Moreover,the fuel conversion efficiency and considerable Faradaic efficiency reveal the compatibility of SFT-SnO_(2)heterostructure electrolyte and ruled-out short-circuiting issue.Further,the first principle calculation provides sufficient information on structure optimization and energy-band structure modulation of SFT-SnO_(2).This strategy will provide new insight into semiconductor-based fuel cell technology to design novel electrolytes.

Al^(3+) doped CeO_(2) for proton conducting fuel cells

Developing high ionic conducting electrolytes is crucial for applying proton-conducting fuel cell(PCFCs)practically.The cur-rent study investigates the effect of alumina on the structural,morphological,electrical,and electrochemical properties of CeO_(2).Lattice oxygen vacancies are induced in CeO_(2) by a general doping concept that enables fast ionic conduction at low-temperature ranges(300-500℃)for PCFCs.Rietveld refinement of the X-ray diffraction(XRD)patterns established the pure cubic fluorite structure of Al-doped CeO_(2)(ADC)samples and confirmed Al ions’fruitful integration in the CeO_(2) lattice.The electronic structure of the alumina-doped ceria of the materials(10ADC,20ADC,and 30ADC)has been investigated.As a result,it was found that the best composition of 30ADC-based electrolytes induced maximum lattice oxygen vacancies.The corresponding PCFC exhibited a maximum power output of 923 mW/cm^(2)at 500℃.Moreover,the investigation proves the proton-conducting ability of alumina-doped ceria-based fuel cells by using an oxide ion-blocking layer.

Large-Scale Carbon Dioxide Storage in Salt Caverns:Evaluation of Operation,Safety,and Potential in China

Underground salt cavern CO_(2) storage(SCCS)offers the dual benefits of enabling extensive CO_(2) storage and facilitating the utilization of CO_(2) resources while contributing the regulation of the carbon market.Its economic and operational advantages over traditional carbon capture,utilization,and storage(CCUS)projects make SCCS a more cost-effective and flexible option.Despite the widespread use of salt caverns for storing various substances,differences exist between SCCS and traditional salt cavern energy storage in terms of gas-tightness,carbon injection,brine extraction control,long-term carbon storage stability,and site selection criteria.These distinctions stem from the unique phase change characteristics of CO_(2) and the application scenarios of SCCS.Therefore,targeted and forward-looking scientific research on SCCS is imperative.This paper introduces the implementation principles and application scenarios of SCCS,emphasizing its connections with carbon emissions,carbon utilization,and renewable energy peak shaving.It delves into the operational characteristics and economic advantages of SCCS compared with other CCUS methods,and addresses associated scientific challenges.In this paper,we establish a pressure equation for carbon injection and brine extraction,that considers the phase change characteristics of CO_(2),and we analyze the pressure during carbon injection.By comparing the viscosities of CO_(2) and other gases,SCCS’s excellent sealing performance is demonstrated.Building on this,we develop a long-term stability evaluation model and associated indices,which analyze the impact of the injection speed and minimum operating pressure on stability.Field countermeasures to ensure stability are proposed.Site selection criteria for SCCS are established,preliminary salt mine sites suitable for SCCS are identified in China,and an initial estimate of achievable carbon storage scale in China is made at over 51.8-77.7 million tons,utilizing only 20%-30%volume of abandoned salt caverns.This paper addresses key scientific and engineering challenges facing SCCS and determines crucial technical parameters,such as the operating pressure,burial depth,and storage scale,and it offers essential guidance for implementing SCCS projects in China.

Tuning Interface Bridging Between MoSe2 and Three‑Dimensional Carbon Framework by Incorporation of MoC Intermediate to Boost Lithium Storage Capability

Interface engineering has been widely explored to improve the electrochemical performances of composite electrodes,which governs the interface charge transfer,electron transportation,and structural stability.Herein,MoC is incorporated into MoSe2/C composite as an intermediate phase to alter the bridging between MoSe2-and nitrogen-doped three-dimensional(3D)carbon framework as MoSe2/MoC/N–C connection,which greatly improve the structural stability,electronic conductivity,and interfacial charge transfer.Moreover,the incorporation of MoC into the composites inhibits the overgrowth of MoSe2 nanosheets on the 3D carbon framework,producing much smaller MoSe2 nanodots.The obtained MoSe2 nanodots with fewer layers,rich edge sites,and heteroatom doping ensure the good kinetics to promote pseudo-capacitance contributions.Employing as anode material for lithium-ion batteries,it shows ultralong cycle life(with 90%capacity retention after 5000 cycles at 2 A g−1)and excellent rate capability.Moreover,the constructed LiFePO4//MoSe2/MoC/N–C full cell exhibits over 86%capacity retention at 2 A g−1 after 300 cycles.The results demonstrate the effectiveness of the interface engineering by incorporation of MoC as interface bridging intermediate to boost the lithium storage capability,which can be extended as a potential general strategy for the interface engineering of composite materials.

An Inquiry into the Application and Preparation of Surfactant in Oil Field

As a commonly used chemical agent,surfactant is used to improve the efficiency of oil-and-gas exploitation.Since the conventional surfactant technology fails to meet the requirements of oil-and-gas resources exploitation currently,this paper deeply researches on the studies of cutting-edge technology of oil-and-gas exploitation,and learns the advanced experience from foreign countries.It aims to point out that the needs of China’s demand for oil-and-gas exploitation can be met with through technology innovation,preparation methods improvement and key technology mastery of surfactant in oil field.

Targeted doping induces interfacial orientation for constructing surface-functionalized Schottky junctions to coordinate redox reactions in water electrolysis

Tuning the surface properties of catalysts is an effective method for accelerating water electrolysis.Herein,we propose a directional doping and interfacial coupling strategy to design two surface-functionalized Schottky junction catalysts for coordinating the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Directional doping with B/S atoms endows amphiphilic g-C_(3)N_(4)with significant n-/p-type semiconductor properties.Further coupling with Fe_(3)C modulates the energy band levels of B-C_(3)N_(4)and S-C_(3)N_(4),thus resulting in functionalized Schottky junction catalysts with specific surface-adsorption properties.The space-charge region generated by the dual modulation induces a local“OH
-and Ht-enriched”environment,thus selectively promoting the kinetic behavior of the OER/HER.Impressively,the designed B-C_(3)N_(4)@Fe_(3)C||S-C_(3)N_(4)@Fe_(3)C pair requires only a low voltage of 1.52 V to achieve efficient water electrolysis at 10 mA cm^(-2).This work highlights the potential of functionalized Schottky junction catalysts for coordinating redox reactions in water electrolysis,thereby resolving the trade-off between catalytic activity and stability.

Energy Conserving Lattice Boltzmann Models for Incompressible Flow Simulations

In this paper,we highlight the benefits resulting from imposing energyconserving equilibria in entropic lattice Boltzmann models for isothermal flows.The advantages are documented through a series of numerical simulations,such as TaylorGreen vortices,cavity flow and flow past a sphere.

Novel LaFe_(2)O_(4)spinel structure with a large oxygen reduction response towards protonic ceramic fuel cell cathode

Highly active and stable electrocatalysts are mandatory for developing high-performance and longlasting fuel cells.The current study demonstrates a high oxygen reduction reaction(ORR)electrocatalytic activity of a novel spinel-structured LaFe_(2)O_(4)via a self-doping strategy.The LaFe_(2)O_(4)demonstrates excellent ORR activity in a protonic ceramic fuel cell(PCFC)at temperature range of 350-500℃.The high ORR activity of LaFe_(2)O_(4)is mainly attributed to the facile release of oxide and proton ions,and improved synergistic incorporation abilities associated with interplay of multivalent Fe^(3+)/Fe^(2+)and La^(3+)ions.Using LaFe_(2)O_(4)as cathode over proton conducting BaZr_(0.4)Ce_(0.4)Y_(0.2)O_(3)(BZCY)electrolyte,the fuel cell has delivered a high-power density of 806 mW/cm^(2)operating at 500℃.Different spectroscopic and calculations methods such as UV-visible,Raman,X-ray photoelectron spectroscopy and density functional theory(DFT)calculations were performed to screen the potential application of LaFe_(2)O_(4)as cathode.This study would help in developing functional cobalt-free ORR electrocatalysts for low temperature-PCFCs(LT-PCFCs)and solid oxide fuel cells(SOFCs)applications.

A novel approach for the optimal arrangement of tube bundles in a 1000-MW condenser

1Introduction The condenser plays a vital role in the operation of a thermal power generation unit.Its primary function is to remove the heat from the steam that is exhausted from the steam turbine,thereby condensing the steam into water.Additionally,it establishes and maintains a specific degree of vacuum at the exhaust port of the steam turbine,facilitating efficient operation of the turbine(Keshvarparast et al.,2020).The vacuum degree of the condenser is affected by physical factors such as steam-side resistance and heat-transfer efficiency.

Estimation of cost savings from participation of electric vehicles in vehicle to grid(V2G)schemes

The storage capacity of the batteries in an electric vehicle(EV)could be utilised to store electrical energy and give it back to the grid when needed by participating in vehicle to grid(V2G)schemes.This participation could be a source of revenue for vehicle owners thus reducing the total charging cost of their EVs.A V2G simulator has been developed using MATLAB to find out the potential cost saving from participation of EVs in V2G schemes.A standard IEEE30 network has been modelled in the simulator which uses the MATPOWER engine to undertake power flow analysis.A novel control algorithm has been developed to take advantage of the difference between the selling and buying electricity prices by charging and discharging EVs at the appropriate time.Two scenarios are simulated to compare the total charging cost of EVs with or without the utilisation of V2G technology within the power system assuming a total of 5000 EVs.The results of the simulation show that the applied control strategy with V2G is able to reduce the charging cost of EVs by 13.6%while satisfying the minimum requirement for state of charge(SoC)of the EV batteries to complete their next journey.

Experimental Study on Deep Desulfurizer in LF Process

CaO-Al2O3-SiO2-CaF2-MgO was selected as the slag system for desulfurization in LF process.The reaction between steel and slag during desulfurization has been simulated by using Factsage software to study the influence of component on the sulfur distribution ratio.In order to research the influence of CaO content,aluminum powder content and its granularity on desulfurization,laboratory experiments have been carried out in a 200 kg inductive furnace.Results showed that the optimal composition of deep desulfurizer is wCaO=64% and aluminium powder 10% with a granularity of 30 μm.Industrial trials showed that the main composition range of final slag in LF process is wCaO=53.0%-57.0%,wAl2O3=23.4%-25.1%,wSiO2=8.1%-10.0%,and wCaF2=3.2%-4.7%.The sulfur mass percent in steel is lower than 0.0008% with a desulfurization rate above 89%.According to the result of industrial production,this desulfurizer could meet the production requirement for ultra-low sulfur steel,of which sulfur mass percent is under 0.0015%

TanDEM-X multiparametric data features in sea ice classification over the Baltic sea

In this study,we assess the potential of X-band Interferometric Synthetic Aperture Radar imagery for automated classification of sea ice over the Baltic Sea.A bistatic SAR scene acquired by the TanDEM-X mission over the Bothnian Bay in March of 2012 was used in the analysis.Backscatter intensity,interferometric coherence magnitude,and interferometric phase have been used as informative features in several classification experiments.Various combinations of classification features were evaluated using Maximum likelihood(ML),Random Forests(RF)and Support Vector Machine(SVM)classifiers to achieve the best possible discrimination between open water and several sea ice types(undeformed ice,ridged ice,moderately deformed ice,brash ice,thick level ice,and new ice).Adding interferometric phase and coherence-magnitude to backscatter-intensity resulted in improved overall classification per-formance compared to using only backscatter-intensity.The RF algorithm appeared to be slightly superior to SVM and ML due to higher overall accuracies,however,at the expense of somewhat longer processing time.The best overall accuracy(OA)for three methodologies were achieved using combination of all tested features were 71.56,72.93,and 72.91%for ML,RF and SVM classifiers,respectively.Compared to OAs of 62.28,66.51,and 63.05%using only backscatter intensity,this indicates strong benefit of SAR interferometry in discriminating different types of sea ice.In contrast to several earlier studies,we were particularly able to successfully discriminate open water and new ice classes.

Comparative analysis of ceramic-carbonate nanocomposite fuel cells using composite GDC/NLC electrolyte with different perovskite structured cathode materials

A comparative analysis of perovskite structured cathode materials, La0.65Sr0.35Mn03 （LSM）, La0.8Sr0.2CoO3 （LSC）, La0.6Sr0.4FeO3 （LSF） and La0.6Sr0.4Co0.2Fe0.803 （LSCF）, was performed for a ceramic-carbonate nanocomposite fuel cell using composite electrolyte consisting of Gd0.1Ce0.9O1.95 （GDC） and a eutectic mixture of Na2CO3 and Li2CO3. The compatibility of these nanocomposite electrode powder materials was investigated under air, CO2 and air/CO2 atmospheres at 550 ℃. Microscopy measurements together with energy dispersive X-ray spectroscopy （EDS） elementary analysis revealed few spots with higher counts of manganese relative to lanthanum and strontium under pure CO2 atmosphere. Furthermore, electrochemical impedance （EIS） analysis showed that LSC had the lowest resistance to oxygen reduction reaction （ORR） （14.12 Ω·cm^2） followed by LSF （15.23 Ω·cm^2）, LSCF （19.38Ω·cm^2） and LSM （ 〉 300 Ω·cm^2）. In addition, low frequency EIS measurements （down to 50 gHz） revealed two additional semi-circles at frequencies around 1 Hz. These semicircles can yield additional information about electrochemical reactions in the device. Finally, a fuel cell was fabricated using GDC/NLC nanocomposite electrolyte and its composite with NiO and LSCF as anode and cathode, respectively. The cell produced an excellent power density of 1.06 W/cm^2 at 550 ℃ under fuel cell conditions.

Droplet Collision Simulation by a Multi-Speed Lattice Boltzmann Method

Realization of the Shan-Chen multiphase flow lattice Boltzmann model is considered in the framework of the higher-order Galilean invariant lattices.The present multiphase lattice Boltzmann model is used in two-dimensional simulation of droplet collisions at high Weber numbers.Results are found to be in a good agreement with experimental findings.

Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid dynamics: mathematical and modelling aspects of porous media

Description of electrolyte fluid dynamics in the electrode compartments by mathematical models can be a powerful tool in the development of redox flow batteries(RFBs)and other electrochemical reactors.In order to determine their predictive capability,turbulent Reynolds-averaged Navier-Stokes(RANS)and free flow plus porous media(Brinkman)models were applied to compute local fluid velocities taking place in a rectangular channel electrochemical flow cell used as the positive half-cell of a cerium-based RFB for laboratory studies.Two different platinized titanium electrodes were considered,a plate plus a turbulence promoter and an expanded metal mesh.Calculated pressure drop was validated against experimental data obtained with typical cerium electrolytes.It was found that the pressure drop values were better described by the RANS approach,whereas the validity of Brinkman equations was strongly dependent on porosity and permeability values of the porous media.