A CO_(2) storage potential evaluation method for saline aquifers in a petroliferous basin

According to the requirements for large-scale project implementation, a four-scale and three-level CO_(2)storage potential evaluation method is proposed for saline aquifers in a petroliferous basin in China, considering geological,engineering and economic factors. The four scales include basin scale, depression scale, play scale and trap scale, and the three levels include theoretical storage capacity, engineering storage capacity, and economic storage capacity. The theoretical storage capacity can be divided into four trapping mechanisms, i.e. structural & stratigraphic trapping, residual trapping, solubility trapping and mineral trapping, depending upon the geological parameters, reservoir conditions and fluid properties in the basin. The engineering storage capacity is affected by the injectivity, storage security pressure, well number, and injection time.The economic storage capacity mainly considers the carbon pricing yield, drilling investment, and operation cost, based on the break-even principle. Application of the method for saline aquifer in the Gaoyou sag of the Subei Basin reveals that the structural & stratigraphic trapping occupies the largest proportion of the theoretical storage capacity, followed by the solubility trapping and the residual trapping, and the mineral trapping takes the lowest proportion. The engineering storage capacity and the economic storage capacity are significantly lower than the theoretical storage capacity when considering the constrains of injectivity, security and economy, respectively accounting for 21.0% and 17.6% of the latter.

Assessment of CO_(2)geological storage capacity based on adsorption isothermal experiments at various temperatures:A case study of No.3 coal in the Qinshui Basin

Carbon dioxide(CO_(2))capture,utilization,and storage(CCUS)is an important pathway for China to achieve its“2060 carbon neutrality”strategy.Geological sequestration of CO_(2)in deep coals is one of the methods of CCUS.Here,the No.3 anthracite in the Qinshui Basin was studied using the superposition of each CO_(2)geological storage category to construct models for theoretical CO_(2)geological storage capacity(TCGSC)assessment,and CO_(2)adsorption capacity variation with depth.CO_(2)geological storage potential of No.3 anthracite coal was assessed by integrating the adsorption capacity with the static storage and dissolution capacities.The results show that(1)CO_(2)adsorption capacities of XJ and SH coals initially increased with depth,peaked at 47.7 cm3/g and 41.5 cm3/g around 1000 m,and later decreased with depth.(2)four assessment areas and their geological model parameters were established based on CO_(2)phase variation and spatial distribution of coal thickness,(3)the abundance of CO_(2)geological storage capacity(ACGSC),which averages 40 cm3/g,shows an analogous circularity-sharp distribution,with the high abundance area influenced by depth and coal rank,and(4)the TCGSC and the effective CO_(2)geological storage capacity(ECGSC)are 9.72 Gt and 6.54 Gt;the gas subcritical area accounted for 76.41%of the total TCGSC.Although adsorption-related storage capacity accounted for more than 90%of total TCGSC,its proportion,however,decreased with depth.Future CO_(2)-ECBM project should focus on highrank coals in gas subcritical and gas-like supercritical areas.Such research will provide significant reference for assessment of CO_(2)geological storage capacity in deep coals.

Raising the capacity of lithium vanadium phosphate via anion and cation co-substitution

The pursuit for batteries with high specific energy provokes the research of high-voltage/capacity cathode materials with superior stability and safety as the alternative for lithium iron phosphate.Herein,using the sol-gel method,a lithium vanadium phosphate with higher average discharge voltage(3.8 V,vs.Li+/Li) was obtained from a single source for Mg2+ and Cl-co-substitution and uniform carbon coating,and a nearly theoretical capacity(130.1 mA h g^-1) and outstanding rate performance(25 C) are acquired together with splendid capacity retention(80%) after 650 cycles.This work reveals that the well-sized anion and cation substitution and uniform carbon coating are of both importance to accelerate kinetic performance in the context of nearly undisturbed crystal structure for other analogue materials.It is anticipated that the electrochemistry comprehension will shed light on preparing cathode materials with high energy density in the future.

Electrochemical reaction mechanism of porous Zn_(2)Ti_(3)O_(8)as a high-performance pseudocapacitive anode for Li-ion batteries

Zn_(2)Ti_(3)O_(8),as a new type of anode material for lithium-ion batteries,is attracting enormous attention because of its low cost and excellent safety.Though decent capacities have been reported,the electrochemical reaction mechanism of Zn_(2)Ti_(3)O_(8)has rarely been studied.In this work,a porous Zn_(2)Ti_(3)O_(8)anode with considerably high capacity(421 mAh/g at 100 mA/g and 209 mAh/g at 5000 mA/g after 1500 cycles)was reported,which is even higher than ever reported titanium-based anodes materials including Li_(4)Ti_(5)O_(12),TiO_(2)and Li_(2)ZnTi_(3)O_(8).Here,for the first time,the accurate theoretical capacity of Zn_(2)Ti_(3)O_(8)was confirmed to be 266.4 mAh/g.It was also found that both intercalation reaction and pseudocapacitance contribute to the actual capacity of Zn_(2)Ti_(3)O_(8),making it possibly higher than the theoretical value.Most importantly,the porous structure of Zn_(2)Ti_(3)O_(8)not only promotes the intercalation reaction,but also induces high pseudocapacitance capacity(225.4 mAh/g),which boosts the reversible capacity.Therefore,it is the outstanding pseudocapacitance capacity of porous Zn_(2)Ti_(3)O_(8)that accounts for high actual capacity exceeding the theoretical one.This work elucidates the superiorities of porous structure and provides an example in designing high-performance electrodes for lithium-ion batteries.