Numerical investigation of cycle performance in compressed air energy storage in aquifers

Compressed air energy storage (CAES) is one of the promising technologies to store the renewable energies such as surplus solar and wind energy in a grid scale. Due to the widespread of aquifers in the world, the compressed air energy storage in aquifers (CAESA) has advantages compared with the compressed air energy storage in caverns and air tanks. The feasibility of aquifers as storage media in CAES system has been demonstrated by numerical models and field tests. This study proposes a numerical model by Transport of Unsaturated Groundwater and Heat Version 3.0/Equation-of-State 3 (TOUGH3/EOS3) to simulate a field-scale study of a novel CAES by storing the compressed air in aquifers. The feasibility of the model has been demonstrated by comparison of simulation results and monitoring data. After that, three types of cycles, which are daily cycle, weekly cycle and monthly cycle, are designed to study their performance within a month working cycle. Their gas saturation show small differences after one month cycle. When the air with temperature of 50 °C injected into aquifers with temperature of 20 °C, after the cycle finished, the air temperature in aquifer of daily cycle are 5.4 °C higher than that of weekly cycle and 10.8 °C higher than that of monthly cycle. It is indicated that during the same cycle periods, the more cycle times, the higher air temperature in aquifers after the cycle. The energy recovery efficiencies for daily cycle, weekly cycle and monthly cycle are 96.96%, 96.27% and 93.15%, respectively. The slight increase of energy recovery efficiencies from daily cycle to monthly cycle indicate that with the same energy storage scales, the energy produced by daily cycle has slight competitiveness. The simulation results can provide references for engineering application in future

Improving product quality and productivity of an antibody-based biotherapeutic using inverted frustoconical shaking bioreactors

The Chinese hamster ovarian (CHO) cells serve as a common choice in biopharmaceutical production, traditionally cultivated in stirred tank bioreactors (STRs). Nevertheless, the pursuit of improved protein quality and production output for commercial purposes demand exploration into new bioreactor types. In this context, inverted frustoconical shaking bioreactors (IFSB) present unique physical properties distinct from STRs. This study aims to compare the production processes of an antibody-based biotherapeutic in both bioreactor types, to enhance production flexibility. The findings indicate that, when compared to STRs, IFSB demonstrates the capability to produce an antibody-based biotherapeutic with either comparable or enhanced bioprocess performance and product quality. IFSB reduces shear damage to cells, enhances viable cell density (VCD), and improves cell state at a 5-L scale. Consequently, this leads to increased protein expression (3.70 g/L vs 2.56 g/L) and improved protein quality, as evidenced by a reduction in acidic variants from 27.0% to 21.5%. Scaling up the culture utilizing the Froude constant and superficial gas velocity ensures stable operation, effective mixing, and gas transfer. The IFSB maintains a high VCD and cell viability at both 50-L and 500-L scales. Product expression levels range from 3.0 to 3.6 g/L, accompanied by an improved acidic variants attribute of 20.6%–22.7%. The IFSB exhibits superior productivity and product quality, underscoring its potential for incorporation into the manufacturing process for antibody-based biotherapeutics. These results establish the foundation for IFSB to become a viable option in producing antibody-based biotherapeutics for clinical and manufacturing applications

Analysis on building industry CO2 emission in Shanghai

With the economic development in Shanghai, a lot of energy has been consumed in the building industry, and is accompanied by a great amount of carbon emissions. Based on the data of energy consumption in the two stages of the building materials production and construction process in Shanghai, a calculation model of CO2 emissions was created, total CO2 emissions have been evaluated during recent ten years, and CO2 emissions influencing factors was identified in each stage. The research results show that CO2 emissions in the stage of building materials production, account for more than 90% of total CO2 emissions, mainly traced from cement, iron and steel industry, and have greater potential for energy conservation and emissions reduction

Adaptive Control of Flapping-Wing Micro Aerial Vehicle with Coupled Dynamics and Unknown Model Parameters

With the complex aerodynamics, the accurate system model of the flapping-wing micro aerial vehicle required for precise control is hard to acquire, meanwhile, due to the unique control strategy, the coupling between the actuators also brings a great challenge to the control of the vehicle. In this paper, we establish a theoretical model of the vehicle. Based on this model, we propose a multiaxial adaptive controller with the reference generator for the attitude and altitude control using the backstepping design method, the stability of this controller is proved by the Lyapunov function. Moreover, a control allocation algorithm is proposed to coordinate the different actuators such that they together produce the desired virtual control efforts. In addition, we detail the lightweight design of the flapping-wing micro aerial vehicle with altitude and attitude sensing onboard. Then, the effectiveness of the proposed control scheme is verified by the simulation and the flight test with multi-axis simultaneous control conducted on this lightweight vehicle. The experimental results show that the controller can maintain hovering flight and ensure the convergence of the adaptive parameters even when the unilateral thrust of the vehicle is not enough due to manufacturing and assembly errors. This work provides an idea for us to explore how insects maintain stable flight in the face of changes in their model parameters

Inconel 740H Prepared by Additive Manufacturing: Microstructure and Mechanical Properties

An Inconel 740H nickel-based alloy was fabricated via wire arc additive manufacturing. The as-welded and heat-treated samples were analyzed to investigate their phase composition, microstructure, crystal structure, and mechanical properties. After heat treatment, the sample exhibited a columnar crystal zone microstructure consisting of a γ matrix + precipitated phase, the remelting zone metallographic structure was a γ matrix + precipitated phase, and the HAZ metallographic structure was a γ matrix + precipitated phase. Transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) were used to show that the welded sample exhibited many dislocations, a few inclusions, and carbides, nitrides, and γ’ precipitates in its crystal structure. In contrast, the crystal structure of the heat-treated sample exhibited a lower number of dislocations and significantly higher carbide and γ’ precipitate content. Moreover, the mechanical performance of these samples was excellent. This heat-treatment process improved the sample strength by about 200 MPa, leading to better high-temperature mechanical properties. This work is anticipated to offer theoretical and experimental support for using additive manufacturing methods in the manufacturing of nickel-based superalloy components

Long-Term Follow-Up of Biological Reconstruction with Free Fibular Graft after Resection of Extremity Diaphyseal Bone Tumors

This study aimed to evaluate the clinical outcomes and complications of reconstruction with a composite free fibula inside other biological grafts. We retrospectively reviewed 26 patients who underwent reconstruction after bone tumor resection of the diaphysis of the long bone. Surgical data, time to bony union, functional outcomes, and complications were evaluated in all cases. The median follow-up was 72.5 months. The limb salvage rate was 100%. Primary osseous union was achieved in 90.4% of the junctions. The union rates at the metaphyseal and diaphyseal junctions were 100% and 85.7%, respectively (p = 0.255). The mean time of bony union in the upper (87.5%) and lower (91.7%) extremity was 4.6 ± 1.6 months and 6.9 ± 2 months, respectively. The mean MSTS score was 27.2 ± 3.2, with a mean MSTS rating of 90.7%. Complications occurred in 15.4% of the cases. The administration of vascularized or non-vascularized grafts did not significantly influence the union time (p = 0.875), functional outcome (p = 0.501), or blood loss (p = 0.189), but showed differences in operation time (p = 0.012) in lower extremity reconstruction. A composite free fibula inside other biological grafts provides a reasonable and durable option for osseous oncologic reconstruction of the long bone diaphysis of the extremities with an acceptable rate of complications. A higher union rate was achieved after secondary bone grafting. In lower-extremity reconstruction, two plates may be considered a better option for internal fixation. Vascularizing the fibula did not significantly affect the union time

Research on the microstructure and properties of antimicrobial stainless steel coatings on Q345R alloy steel by electron beam surface coating

In this study, 304 antimicrobial stainless steel coatings were prepared by the electron beam melting of antimicrobial stainless steel powder, in an attempt to enhance the surface properties of Q345R steel. Besides, the effect of Cu-containing 304 powder coatings on the microstructure, mechanical properties, and electrochemical properties of the Q345R surface was investigated. The results indicated that the coating grain was refined, the dislocation density was increased, and both the plasticity and toughness were enhanced after the electron beam surface coating (EBSC) treatment. Additionally, the hardness of coatings was also enhanced under the three beam currents due to grain refinement and dislocation strengthening. At a beam current of 28 mA, the coating hardness reached a maximum of 384.078 HV, representing a two-fold increase compared with the base material (BM) hardness of 131.048 HV. Moreover, the abrasion resistance of the coating was superior to that of the BM. At a beam current of 28 mA, the wear volume and wear rate were minimized to only 10 % of the wear volume of substrates. In galvanic corrosion measurements, the coatings displayed better corrosion resistance than the substrates, and these samples at a beam current of 28 mA exhibited the best corrosion resistance. Overall, the E-beam surface melting 304 stainless steel coating can effectively improve the properties of Q345R carbon steel

Constraints of hydrodynamic conditions on gas reservoirs in Dongying depression and its enlightenment to CO2 storage target area

A large number of natural gas reservoirs in Dongying depression and its surrounding areas indicate that there are good conditions for CO2 geological storage in these areas. To optimize the target area suitable for CO2 storage, through data collection and comprehensive analysis of Dongying basin flow field, this study summarized the main controlling factors and occurrence modes of natural gas accumulation in Dongying depression and its surrounding areas with a buried depth of 500-1500 m, and analyzed the restrictive effect of underground hydrodynamic field on the formation of natural gas reservoirs. The results show the migration pathways of shallow gas reservoirs can be divided into lateral migration pathways and vertical migration pathways based on the characteristics and modes of underground fluid movement. The lateral type is mainly distributed in the high uplift belt at the edge of the depression, and the vertical type is mainly distributed in the depression area in the basin. Compaction flow is the main driving force for the upward migration of the deep gas source in the center of the depression. A part of the deep gas moves for a long distance from the center of the depression to the edge of the depression, forming a closed hydrodynamic trap and a lateral shallow gas reservoir at the junction of compaction flow and gravity flow in the high convex part of the edge of the depression. The other part of deep gas, driven by compaction flow, migrates vertically along the high porosity and permeability fault zone and accumulates in the trap at the top. Lithologic traps caused by fault dislocation are relatively developed, which together with hydrodynamic traps form an effective trap of gas and form a vertical shallow gas reservoir. The most favorable target area for CO2 storage in the shallow part (500-1500 m) of Dongying depression is mainly located in the west and north direction of the depression, such as Gaoqing Uplift, Linfanjia Uplift, Binxian Uplift, Chenjiazhuang Uplift, Guangrao Uplift, and their surrounding areas. The vertical fault development areas of Guangrao uplift, Qingtuozi uplift, and other depressions in the east are favorable targets for CO2 storage in the shallows

Robust Sampled-data H∞ Control Of Flapping Wing Micro Aerial Vehicles With Parameter Uncertainties and Actuator Saturation

Robust control is essential to the flapping wing micro aerial vehicle (FWMAV) due to model uncertainties, environmental or self changes during flight, such as the change of drag coefficient caused by airflow and the asymmetric effect caused by wing damage. This paper proposes a robust H∞ controller synthesis scheme for parameter-varying FWMAV systems with sampling measurement and control input saturation. A linear parameter varying (LPV) model is established to characterize the nonlinear FWMAV model with uncertainties. We introduce an input delay approach to transform the sampled-data system into a continuous system with time delay. A nonconvex optimization with bilinear matrix inequalities (BMI) is established to synthesize the proposed robust output-feedback controller with the PID structure, ensuring the H∞ performance of the closed loop. A Lyapunov function is proposed to ensure the asymptotic stability of the closed loop system. The BMI problem is restricted furthermore and transformed to a convex optimization problem with linear matrix inequalities (LMI) constraints, making the method computationally practical. The numerical simulations show that the proposed controller possesses superior performance and strong robustness in the FWMAV compared with four other controllers.</p

Geological carbon storage and compressed gas energy storage: current status, challenges, and prospects

Carbon capture and storage (CCS) and geological energy storage are essential technologies for mitigating global warming and achieving China’s “dual carbon” goals. Carbon storage involves injecting carbon dioxide into suitable geological formations at depth of 800 meters or more for permanent isolation. Geological energy storage, on the other hand, involves compressing air or other gases using surplus electricity during off-peak hours and temporarily storing them in underground reservoirs. These gases are then released during peak hours for power generation. Both technologies share commonalities in reservoir selection, with aquifers, depleted oil and gas reservoirs, and salt caverns all serving as potential storage sites. Carbon storage demands long-term containment, while geological energy storage necessitates multiple cycles of storage and release, requiring careful consideration during site evaluation. CCS projects are rapidly increasing globally, evolving towards networked and clustered configurations. In China, CCS projects are primarily focused on CO2-enhanced oil recovery, with fewer dedicated storage projects. However, direct storage projects are projected to dominate in the future and are also transitioning towards clustered development. China possesses favorable geological conditions for carbon storage, with relatively accurate estimates for oil and gas reservoir storage potential. Nevertheless, significant uncertainties persist regarding the storage capacity of saline aquifers. Compressed air energy storage in salt caverns is currently the predominant type of geological energy storage projects. Germany, the USA, and China have a total of five operating compressed air salt cavern energy storage power plants. China has abundant salt cavern resources, albeit with complex geological conditions. Suitable construction sites are concentrated in the eastern regions, and numerous projects are already underway. Compared to salt caverns, porous formations such as aquifers and depleted oil and gas reservoirs are more widespread and offer higher storage potential. However, technical challenges related to multiphase flow and chemical reactions need to be addressed. However, current site selection, potential assessment, efficiency optimization, and monitoring technologies face considerable challenges in meeting the demands of large-scale practical applications. Traditional hydrogeological exploration methods prove inadequate for selecting suitable sites, highlighting the need for efficient monitoring and risk control techniques. Additionally, there is a lack of cost-effective and accurate continuous monitoring technologies specifically designed for pressure and stress changes in storage and caprock formations. The development of key equipment components, such as monitoring and power generation systems, with independent intellectual property rights remains limited. Moreover, our reservoir simulation software requires further advancements to effectively simulate complex reservoirs at large scales. It is crucial to prioritize research and development in resource exploration, site selection technologies, and engineering equipment for both carbon sequestration and geological energy storage. The establishment of diverse demonstration projects and facilities for various storage options such as saline aquifers, depleted oil/gas fields are needed in the future as well