Development status and prospect of underground thermal energy storage technology

Underground Thermal Energy Storage(UTES)store unstable and non-continuous energy underground,releasing stable heat energy on demand.This effectively improve energy utilization and optimize energy allocation.As UTES technology advances,accommodating greater depth,higher temperature and multi-energy complementarity,new research challenges emerge.This paper comprehensively provides a systematic summary of the current research status of UTES.It categorized different types of UTES systems,analyzes the applicability of key technologies of UTES,and evaluate their economic and environmental benefits.Moreover,this paper identifies existing issues with UTES,such as injection blockage,wellbore scaling and corrosion,seepage and heat transfer in cracks,etc.It suggests deepening the research on blockage formation mechanism and plugging prevention technology,improving the study of anticorrosive materials and water treatment technology,and enhancing the investigation of reservoir fracture network characterization technology and seepage heat transfer.These recommendations serve as valuable references for promoting the high-quality development of UTES.

Challenges and progresses of energy storage technology and its application in power systems

As a flexible power source,energy storage has many potential applications in renewable energy generation grid integration,power transmission and distribution,distributed generation,micro grid and ancillary services such as frequency regulation,etc.In this paper,the latest energy storage technology profile is analyzed and summarized,in terms of technology maturity,efficiency,scale,lifespan,cost and applications,taking into consideration their impact on the whole power system,including generation,transmission,distribution and utilization.The application scenarios of energy storage technologies are reviewed and investigated,and global and Chinese potential markets for energy storage applications are described.The challenges of large-scale energy storage application in power systems are presented from the aspect of technical and economic considerations.Meanwhile the development prospect of global energy storage market is forecasted,and application prospect of energy storage is analyzed.

A Review of Seasonal Hydrogen Storage Multi-Energy Systems Based on Temporal and Spatial Characteristics

The temporal and spatial characteristics of seasonal hydrogen storage will play a very important role in the coupling of multi-energy systems.This essay believes that there are several key issues worth noting in the seasonal hydrogen storage coupled multi-energy system,namely,hydrogen storage methods,coupling models,and benefit evaluation.Through research,this article innovatively divides seasonal hydrogen storage into two types:space transfer hydrogen storage technology and time transfer physical property conversion hydrogen storage technology.Then sort out the two most typical seasonal hydrogen storage multi-energy system application scenarios and their hydrogen storage unit models.Finally,it is shown that hydrogen storage methods should be selected according to different periods of time and regions,and the benefits should be evaluated before they can be used in practice.This review study is applicable to the process of coupling seasonal hydrogen storage in multi-energy systems.Hydrogen energy is used as an intermediate energy link for the selection,evaluation and modeling of the optimal selection and rational utilization.

RECENT ADVANCES IN HYDRATE-BASED TECHNOLOGIES FOR NATURAL GAS STORAGE——A REVIEW

Interest in the possibility of storing and transporting natural gas in the form of clathrate hydrates has been increasing in recent years, particularly in some gas-importing and exporting countries.The technologies necessary for realizing this possibility may be classified into those relevant to the four serial processes (a) the formation of a hydrate, (b) the processing (dewatering, pelletizing, etc. ) of the formed hydrate, (c) the storage and transportation of the processed hydrate, and (d) the regasification (dissociation) of the hydrate. The technological development of any of these processes is still at an early stage. For hydrate formation, for example, various rival operations have been proposed. However,many of them have never been subjected to actual tests for practical use. More efforts are required for examining the different hydrate-formation technologies and for rating them by comparison. The general design of the processing of the formed hydrate inevitably depends on both the hydrate-formation process and the storage/transportation process, hence it has a wide variability. The major uncertainty in the storage-process design lies in the as-yet unclarified utility of the "self-preservation" effect of the naturalgas hydrates. The process design as well as the relevant cost evaluation should strongly depend on whether the hydrates are well preserved at atmospheric pressure in large-scale storage facilities. The regasification process has been studied less extensively than the former processes. The state of the art of the technological development in each of the serial processes is reviewed, placing emphasis on the hydrate formation process.

Study on High Rate Discharge Performance and Mechanism of AB_5 Type Hydrogen Storage Alloys

The effects of surface treatment, particle size distribution,rare earth composition and B additive on the high rate discharge performance of hydrogen storage alloys were investigated. It is found that the activity, discharge capacity and high rate dischargeability of the alloys are improved after physical and chemical modification as a result of the increase of the surface area and formation of the electrocatalysis layers, which increase both the electrochemical reaction rate on the alloy surface and H diffusion rate in the alloy bulk. It is also found that both the over-coarse and over-fine particle size increase the contact resistance of the electrode, resulting in a decrease of discharge capacity, deterioration of high rate dischargeability and lower discharge plateau. In another word, a suitable particle size distribution can enhance the alloy activity, discharge capacity and high rate dischargeability. In addition, the high rate dischargeability is enhanced by increasing La content and decreasing Ce content of the alloy composition because of enlargement of the unit cell volume and the improvement of the surface activity. Moreover, B additive resultes in the formation of the second phase, and makes the alloys easier pulverization, which greatly improves the activity, discharge capacity and high rate dischargeability.

Research of heat treatment of low-Co AB_5 type hydrogen storage alloys for MH-Ni batteries

The effects of low-Co AB_5 type hydrogen storage alloys prepared by quenchingand annealing on the performances of MH-Ni batteries were investigated, and the characteristics ofthe low-Co AB_5 type hydrogen storage alloys were compared with those of the high-Co AB_5 typehydrogen storage alloy as well. The results showed that the faster the cooling of the low-Cohydrogen storage alloy is, the better homogeneity of the chemical composition for the alloy and thelonger cycle life of the battery are, but the electrochemical discharge capacity and high-ratedischarge ability are reduced. The high-rate discharge ability and charge retention of MH-Nibatteries for the conventional as-cast annealed low-Co hydrogen storage alloy were superior to thosefor the rapidly quenched low-Co hydrogen storage alloy and the high-Co hydrogen storage alloy, buta little inferior in the cycle life.

Post lithium ion batteries for emerging energy storage technologies

It is obvious that in the next ten years,lithium ion batteries are still the dominating power source for a wide range of products including consumable electronics,vehicles(cars,motorbikes,scooters,buses),drones,and even robots and tanks.However,in the pursuit of cost-effective,safety-reliable,and highly efficient energy storage technologies,researchers are developing

Porous polybenzimidazole membranes with positive charges enable an excellent anti-fouling ability for vanadium-methylene blue flow battery

A cost-effective, high-performance and highly stable membrane has always been in intensively needed in aqueous organic-based flow batteries. Here we present a porous polybenzimidazole(PBI) membrane with positive charges that endow the membrane with a high rejection and an excellent anti-fouling ability for target organic molecule and asymmetric structure that affords a high conductivity for vanadiummethylene blue flow battery(V-MB FB). The morphologies and thickness of separating layer in particular of the porous PBI can be well adjusted by simply altering the polymer concentration in the cast solution and further afford the membrane with a controllable property in terms of both ion selectivity and ion conductivity. As a result, a V-MB FB assembled with a porous PBI membrane delivers a coulombic efficiency(CE) of 99.45% and an energy efficiency(EE) of 86.10% at a current density of 40 mA cm^(-2), which is 12% higher than that afforded by a Nafion 212 membrane. Most importantly, the V-MB FB demonstrates a methylene blue(MB) utilization of 97.55% at a theoretical capacity of 32.16 Ah L^(-1)(based on the concentration of MB in the electrolyte) because of the high ion conductivity of the membrane, which favors reducing the cost of a battery. The results suggest that the designed porous PBI membranes exhibit a very promising prospect for methylene blue-vanadium flow battery.

Economic potentials of energy storage technologies in electricity markets with renewables

The increasing penetration of renewables in power systems urgently entails the utilization of energy storage technologies.As the development of energy storage technologies depends highly on the profitability in electricity markets,to evaluate the economic potentials for various types of energy storage technologies under the compre-hensive market environment is of great significance.To this end,this study aims at conducting a quantitative analysis on the economic potentials for typical energy storage technologies by establishing a joint clearing model for electric energy and ancillary service(AS)markets considering the operating features of energy storage systems(ESSs).Furthermore,a test system is adopted for numerical analysis that accurately represents for the real-world operation characteristics of power systems in China,with which the market prices,and operation schedules and profitability of ESSs are comparatively studied.The proposed methodology and results could provide benefi-cial references for the modifications on electricity markets and the development of ESSs towards the increasing penetration of renewables in power systems.

满足运载火箭测控需求的Ka频段CTDRSS终端技术

To meet the application requirements for a Ka-band space-based TT&C terminal for a launch vehicle,this paper proposes the implementation scheme of a space-based TT&C terminal,analyzes and solves the miniaturized design of equipment and the key technology for high-efficiency heat dissipation.The phased array antenna test shows that without external heat dissipation measures,the phased array antenna can work for a long time to meet the working requirements of launch vehicle,which has been verified in the LM-8 mission,and has wide engineering application prospects.

Truth and False-carbon Dioxide Mitigation Technologies

Research progress is required to be enhanced for those storage technologies which store CO_(2)fast and permanently.However,temporary storage technologies importance cannot be denied to immediately reduce global warming and reduce higher CO_(2)concentration in the atmosphere.Continuous CO_(2)storage facilities,semi-batch and batch pilot plants deemed necessary to build for future survival of the earth planet.Membranes can be used to separate CO_(2)from common flue gases followed by mineral carbonation to convert CO_(2)into stable carbonates.Modifications in cement industry,coal fired power plants,fertilizer industries and other chemical process industries appears essential.

Highly stable side-chain-type cardo poly(aryl ether ketone)s membranes for vanadium flow battery

Vanadium flow batteries(VFBs)have drawn considerable attention as an emerging technology for largescale energy storage systems(ESSs).One of the pivotal challenges is the availability of eligible ion exchange membranes(ICMs)that provide high ion selectivity,proton conductivity,and stability under rigorous condition.Herein,a‘side-chain-type’strategy has been employed to fabricate highly stable phenolphthalein-based cardo poly(arylene ether ketone)s(PAEKs)membrane with low area resistance(0.058Ωcm^(2)),in which flexible alkyl spacers effectively alleviated inductive withdrawing effect from terminal ion exchange groups thus enabling a stable backbone.The assembled VFBs based on PAEKs bearing pendent alkyl chain terminated with quaternary ammonium(Q-PPhEK)demonstrated an energy efficiency above 80%over 700 cycles at 160 mA/cm^(2).Such a remarkable results revealed that the side-chain-type strategy contributed to enhancing the ICMs stability in strong oxidizing environment,meanwhile,more interesting backbones would be woken with this design engaging in stable ICMs for VFBs.

Overview of the development and application of wind energy in New Zealand

The restructuring of the energy industry is imperative,as New Zealand strives to reduce greenhouse gas emissions.New Zealand has abundant renewable energy resources,and about 85%of current electricity generation is from renewable energy sources.However,in recent years,it appears that a considerable fraction of wind energy has been underutilized.This article reviews the history,current status,and future trends of wind energy development in New Zealand.The main challenges to the current development of wind energy are summarized compared to other countries.The main challenges come from the bi-cultural influence,environmental influence,and economic and social influence due to the variable nature of wind power,it is critical to store and operate power safely and reliably during peak power generation periods.This article compares seven mainstream wind energy storage technologies and analyzes the best solution for wind energy storage in New Zealand.This article analyzes the feasibility of using small-scale household(standard power rating range from 0.004 to 16 kW)wind turbines in New Zealand cities regarding their construction and operation process.The life cycle and the maximum capacity coefficient of such small-scale wind turbines are overviewed via three case studies and later compared with large commercial wind turbines(standard power rating ranges from 1 to 3 MW)in power generation capacity.It has been found that small-scale household wind turbines have notable power generation potential and economic benefits in the long term.

An 8 bit 1 MS/s SAR ADC with 7.72-ENOB

This paper presents a low power 8-bit 1 MS/s SAR ADC with 7.72-bit ENOB. Without an op-amp, an improved segmented capacitor DAC is proposed to reduce the capacitance and the chip area. A dynamic latch comparator with output offset voltage storage technology is used to improve the precision. Adding an extra positive feedback in the latch is to increase the speed. What is more, two pairs of CMOS switches are utilized to eliminate the kickback noise introduced by the latch. The proposed SAR ADC was fabricated in SMIC 0.18μm CMOS technology. The measured results show that this design achieves an SFDR of 61.8 dB and an ENOB of 7.72 bits, and it consumes 67.5μW with the FOM of 312 fJ/conversion-step at 1 MS/s sample under 1.8 V power supply.