Large-Scale Underground Storage of Renewable Energy Coupled with Power-to-X:Challenges,Trends,and Potentials in China

1.Introduction Promoting the green and low-carbon transition of energy systems and constructing a new renewable-dominated power system is essential to achieving carbon neutrality in China[1,2].Furthermore,implementing electrification and hydrogenation strategies to address energy consumption is necessary for a successful energy transition.China’s share of electricity in its total energy consumption is estimated to increase from 26%in 2021 to more than 70%by 2060.

Thermochemical splitting of CO_(2) on perovskites for CO production: A review

Energy supply dominated by fossil energy has been and remains the main cause of carbon dioxide emissions,the major greenhouse gas leading to the current grave climate change challenges.Many technical pathways have been proposed to address the challenges.Carbon capture and utilization(CCU) represents one of the approaches and thermochemical CO_(2) splitting driven by thermal energy is a subset of the CCU,which converts the captured CO_(2) into CO and makes it possible to achieve closed-loop carbon recirculation.Redox-active catalysts are among the most critical components of the thermochemical splitting cycles and perovskites are regarded as the most promising catalysts.Here we review the latest advancements in thermochemical cycles based on perovskites,covering thermodynamic principles,material modifications,reaction kinetics,oxygen pressure control,circular strategies,and demonstrations to provide a comprehensive overview of the topical area.Thermochemical cycles based on such materials require the consideration of trade-off between cost and efficiency,which is related to actual material used,operation mode,oxygen removal,and heat recovery.Lots of efforts have been made towards improving reaction rates,conversion efficiency and cycling stability,materials related research has been lacking-a key aspect affecting the performance across all above aspects.Double perovskites and composite perovskites arise recently as a potentially promising addition to material candidates.For such materials,more effective oxygen removal would be needed to enhance the overall efficiency,for which thermochemical or electrochemical oxygen pumps could contribute to efficient oxygen removal as well as serve as means for inert gas regeneration.The integration of thermochemical CO_(2) splitting process with downstream fuel production and other processes could reduce costs and increase efficiency of the technology.This represents one of the directions for the future research.

Gleaning insights from German energy transition and large-scale underground energy storage for China’s carbon neutrality

The global energy transition is a widespread phenomenon that requires international exchange of experiences and mutual learning.Germany’s success in its first phase of energy transition can be attributed to its adoption of smart energy technology and implementation of electricity futures and spot marketization,which enabled the achievement of multiple energy spatial–temporal complementarities and overall grid balance through energy conversion and reconversion technologies.While China can draw from Germany’s experience to inform its own energy transition efforts,its 11-fold higher annual electricity consumption requires a distinct approach.We recommend a clean energy system based on smart sector coupling(ENSYSCO)as a suitable pathway for achieving sustainable energy in China,given that renewable energy is expected to guarantee 85%of China’s energy production by 2060,requiring significant future electricity storage capacity.Nonetheless,renewable energy storage remains a significant challenge.We propose four large-scale underground energy storage methods based on ENSYSCO to address this challenge,while considering China’s national conditions.These proposals have culminated in pilot projects for large-scale underground energy storage in China,which we believe is a necessary choice for achieving carbon neutrality in China and enabling efficient and safe grid integration of renewable energy within the framework of ENSYSCO.

锌基镀层热成形钢裂纹的产生、扩展机理及高温力学性能研究

本文通过锌基镀层热成形钢的Gleeble试验和实际零件热冲压试验,在材料高温性能分析的基础上,建立了材料模型,用于高精度地拟合真应力和真应变之间的关系,进而研究成形温度、铁素体形成和弯曲变形对液态锌致基板脆裂(LMIE)的影响。结果表明,真应力随着变形温度的下降而增加。当变形温度为820℃时,LMIE导致真应变较低,约为0.13。根据Gleeble热模拟测试和实际零件试验结果,建议成形温度为720℃,可以避免LMIE并保证材料的力学性能。在实际应用中,拉应力容易导致微裂纹的产生,而压应力可以抑制微裂纹的产生。随着成形温度的降低,镀层中微裂纹的数量和宽度降低,同时镀层厚度增加。镀层主要为固态α-Fe(Zn)相。通过减少在加热保温和成形过程中的液态相可以减少甚至避免LMIE裂纹的产生。

Polycrystalline ZSM-5 Aggregates Induced by Seed and Catalytic Performance in Methanol to Hydrocarbon

Synthesis of ZSM-5 zeolite typically utilizes small molecule polyamines or quaternary ammonium salts as organic structure guiding agent(OSDA).By contrast,the OSDA-free hydrothermal synthesis system eliminates the use of organic templates and the subsequent calcination procedure.This not only reduces the cost of synthesis,but also prevents environmental pollution from the combustion of organic templates,representing an eco-friendly approach.Despite this,literature suggests that even so-called template-free synthesis systems often involve trace amount of organic substances like alcohol.In the present work,a calcined commercial ZSM-5 zeolite was served as seed,with sodium aluminate as aluminum source and silica sol as silicon source,ensuring an entirely template-free synthesis system.Polycrystalline ZSM-5 aggregates consisted of rod-like nanocrystals were successfully prepared in the completely OSDA-free system.Effects of the Si/Al ratio in ZSM-5 seed,dosage and crystallization conditions such as crystallization temperature and crystallization time on ZSM-5 synthesis were investigated.The results show that a highly crystallinity ZSM-5 aggregate consisting of primary nano-sized crystals less than 100 nm is produced from a gel precursor with 5.6%(in mass)seed after hydrothermal treatment for 48 h.Furthermore,the Si/Al ratio in ZSM-5 seed has little effect on the topological structure and pore structure of the synthesized samples.However,the seeds with a low Si/Al ratio facilitate faster crystallization of zeolite and enhance the acidity,especially the strong acid centers,of the catalyst.The catalytic performance of the synthesized polycrystalline ZSM-5 was evaluated during dehydration of methanol and compared with a commercial reference ZSM-5r.The results exhibit that as compared with the reference catalyst,the fabricated sample has a longer catalytic lifetime(16 h vs 8 h)attributed to its hierarchical pores derived from the loosely packed primary nanoparticles.Additionally,the prepared polycrystalline catalyst also exhibits a higher aromatics selectivity(28.1%-29.8%vs 26.5%).

A preliminary site selection system for underground hydrogen storage in salt caverns and its application in Pingdingshan,China

Large‐scale underground hydrogen storage(UHS)provides a promising method for increasing the role of hydrogen in the process of carbon neutrality and energy transition.Of all the existing storage deposits,salt caverns are recognized as ideal sites for pure hydrogen storage.Evaluation and optimization of site selection for hydrogen storage facilities in salt caverns have become significant issues.In this article,the software CiteSpace is used to analyze and filter hot topics in published research.Based on a detailed classification and analysis,a“four‐factor”model for the site selection of salt cavern hydrogen storage is proposed,encompassing the dynamic demands of hydrogen energy,geological,hydrological,and ground factors of salt mines.Subsequently,20 basic indicators for comprehensive suitability grading of the target site were screened using the analytic hierarchy process and expert survey methods were adopted,which provided a preliminary site selection system for salt cavern hydrogen storage.Ultimately,the developed system was applied for the evaluation of salt cavern hydrogen storage sites in the salt mines of Pingdingshan City,Henan Province,thereby confirming its rationality and effectiveness.This research provides a feasible method and theoretical basis for the site selection of UHS in salt caverns in China.

Life Cycle Assessment on Real Time in a Coffee Machine

The environmental impact during the preparation of coffee beverages was evaluated on real time. The functional unit is a cup of coffee prepared from 7 g of ground coffee and 125 mL of tap water. The boundaries system considered are assembly process, electricity process, tap water process, coffee process and municipal waste process. Based on boundary system, the life cycle inventory is carbon dioxide, 50.31 g; coal, brown, 53.72 rag; coal hard, 0.9906 g; dinitrogen monoxide, 0.9575 mg; natural gas, 0.0020 m^3; methane, fossil, 13.82 mg; oil, crude, 1.012 g; uranium, 15.02 ug. The life cycle impact assessment is determined using the sum of the contributions of the impacts shown in the inventory analysis, each one multiplied by a coefficient called the ＂characterization factor＂, which indicates the scale of the potential contributed by the individual substance to the effect. The results show the advantages of using the LCA （life cycle assessment） on real time as it provides information from both quality and environmental parameters allowing taking actions based on timely information. The preparation of a cup of coffee produced an environmental load of 50.9 g of CO2 equivalents and Non Renewable energy equivalents to 151 kJ; the sugar process and materials transportation were not considered.

Boosting Lithium Storage in Graphene-Sandwiched Cathodes Containing Multi-Carbonyl Polyquinoneimine Nanosheets

Carbonyl polymers as booming electrode materials for lithium-organic batteries are currently limited by low practical capacities and poor rate performance due to their inherent electronic insulation and microscopic agglomeration morphologies.Herein graphene/carbonyl-enriched polyquinoneimine(PQI@Gr)composites were readily prepared by in situ hydrothermal polycondensation of dianhydride and anthraquinone co-monomer salts in the presence of graphene oxide(GO).Conductive graphene sheets derived from hydrothermal reduction of GO are fully sandwiched between densely interlaced quinone-containing polyimide nanosheets.Remarkably,the as-fabricated PQI@Gr cathodes exhibit much larger specific capacity(205 mAh g^(-1)at 0.1 A g^(-1)),higher carbonyl utilization(up to 89.9%),and better rate capability(179.4 mAh g^(-1)at 5.0 A g^(-1))due to a surface-dominated capacitive process via fast kinetics compared to bare PQI electrode(162.5 mAh g^(-1)at 0.1 A g^(-1);67.5%;96.9 mAh g^(-1)at 5 A g^(-1)).The capacity retention as high as 73%for PQI@Gr is also achieved over ultra-long 10000 cycles at 5.0 A g^(-1).Such outstanding electrochemical performances are attributable to the combined merits of polyimides and polyquinones,and robust 3D hierarchical heterostructures with efficient conductive networks,abundant porous channels for electrolyte infiltration and ion accessibility,and highly exposed carbonyl groups.This work offers new insights into the development of high-performance polymer electrodes for sustainable batteries.

Emerging Carbonyl Polymers as Sustainable Electrode Materials for Lithium-Free Metal-Ion Batteries

Lithium-ion batteries using inorganic electrode materials have been long demonstrated as the most promising power supplies for portable electronics,electric vehicles,and smart grids.However,the increasing cost and descending availability of lithium resources in combination with the limited electrochemical performance and eco-sustainability have created serious concerns with the competitiveness of lithium-ion batteries.There is a pressing need for the discovery of new redox chemistries between the alternative host materials and charge carriers.Organic nonlithium batteries using organic electrodes have recently attracted considerable interests as the future substitutes for energy storage systems,because of their combined merits(e.g.,natural abundance,rich chemistry of organics,rapid kinetics,and multielectron redox)of Li-free batteries and organic electrodes.Herein,an overview on the state-of-the-art developments of emerging carbonyl polymers for nonlithium metal-ion batteries is comprehensively presented with a primary focus on polyquinones and polyimides from the perspective of chain engineering.Six distinct categories,including monovalent(Na^(+),K^(+)) and multivalent(Mg^(2+),Zn^(2+),Ca^(2+),Al^(3+)) metal-ions batteries are individually outlined.Advantages of polymer electrode materials and characteristics of charge storage mechanisms are highlighted.Some key performance parameters such as specific capacity,rate capability,and cycle stability are carefully discussed.Moreover,aqueous nonlithium batteries based on carbonyl polymers are specially scrutinized due to the less reactivity of Li-free metals when exposed in aqueous electrolytes and ambient atmosphere.Current challenges and future prospects of developing polymer-based batteries are proposed finally.This review provides a fundamental guidance for the future advancement of next-generation sustainable batteries beyond lithium-ion batteries.

Numerical simulation of impact and solidification of melting dust on spherical bead surface and experimental validation

The impact and solidification processes of single melting tin dust at the micron scale on a spherical bead were numerically studied with hot flue gas flow. The geometrical evolution of dust impacting on hot bead and spreading without solidification involved initial spreading, retraction and oscillation, and stabilizing. The increased impact angle was found to reduce maximum spread area, weaken retraction and oscillation, and raise steady spread area. Dust impacting on cold bead completely solidified after liquid spreading and solidification without retraction and oscillation. Increased impact angle raised solidification sliding distance, whereas it reduced solidification spread area. Then, the effects of bead temperature, dust inlet velocity and size on the sliding and spreading of dust were studied, and the results indicated that increasing bead temperature, dust inlet velocity and size could raise solidification sliding distance and solidification spread area. With the dusts continually impacting on the bed, a dust layer forms at the front of bead, being different from that of solid dust, which becomes thick firstly, and then spreads from bead front to sides.

Dust distribution of solid and adhesive mixed dust in a granular bed filter

Granular bed filters can effectively filter adhesive dust in high-temperature flue gas.In this study.polyvinyl chloride(PVC)powder was used as adhesive dust,and the mixture of PVC and ash powder was used to simulate solid and adhesive mixed dust.The effects of gas temperature,velocity,and inlet adhesive dust mass content on dust distribution in granular bed(GBF)were discussed.Results show that the mixed dust mainly accumulates on the upper part of the granular bed,and the mass of the collected dust decreases exponentially from the upper layer to the bottom layer in the GBF.The adhesive dust content collected in each layer differs from that of the incoming dust,and their deviation varies approximately linearly along with the depth of the bed.The total dust distribution and adhesive dust content deviation are influenced by gas temperature and inlet adhesive dust content but independent of gas velocity.The correlations of dust distribution of solid and adhesive mixed dust are presented based on the experimental results.

Experimental study on filtering mixed solid-liquid dust with a sliding granular bed filter

The filtration of mixed dust that included a small number of melted(liquid)particles was studied in an experimental granular bed filter(GBF).Results show that the collection efficiency of dust containing melted particles is higher than that of dust composed of solid particles but the pressure drop from the former is higher than that of the latter.The collection efficiency and pressure drop increase as the concentration of melted particles increases.A surface sliding GBF exhibits good comprehensive performance when filtering dust,especially dust containing a mix of solid and liquid particles.The effects of the gas temperature,gas velocity,sliding filter bed thickness,and sliding collector flux on filter performance were also examined.Based on the experimental results,correlations for the collection efficiency and pressure drop for mixed dust are presented.