Citric acid is one of the most productive biomass organic acids in the world and has been widely used. In this paper, we used reduced iron powder as iron source, citric acid as multidentate ligand and carbon source, and used ammonia to enhance the coordination solubilization ability of citric acid to iron powder, so that it could quickly form a homogeneous complex solgel, which was then carbonized to obtain carboncoated coreshell ironbased FischerTropsch catalyst. In the performance test, the catalyst synthesized by direct dissolution of iron powder with citric acid exhibited remarkable catalytic activity and stability, giving the CO conversion of 99.2%, C5+ hydrocarbon selectivity of 53%, and the CO conversion activity was stably kept above 97.3% for a time on stream of 168 h. The citric acid coordination method is greener and safer, which avoid the use of iron salts such as ferric nitrate, and the risk of explosion and toxic gases in the reduction process of iron salts. This synthesis method provides a new idea for the green and safe production of catalysts.

The structure of flow channel is a critical factor affecting the performance of proton exchange membrane fuel cell (PEMFC). Optimizing the structure of the flow channel is essential for enhancing the performance and service life of PEMFC. Compared to straight channels, channels with varying shapes can improve reactant gas transport, thereby improving the output performance of the cell. In this study, a serrated channel with periodic crosssectional contraction is proposed. To analyze the transport characteristics and performance of this design, a three dimensional, Multiphysics coupled PEMFC model was developed using computational fluid dynamics (CFD) in COMSOL Multiphysics. The effects of the width and cycle length of the flow channel crosssection on the performance of the fuel cell was investigated. The results show that under high current density, the maximum net power of the serrated channel is increased by 6.12% compared to the straight channel, along with enhanced oxygen transport and liquid water removal. For the serrated flow channel, under the same flow rate conditions, moderate narrowing of the periodic contraction's minimum width improves oxygen distribution uniformity and drainage efficiency. Additionally, moderately reducing the contraction periodicity promotes gas flow velocity uniformity. The serrated channel with a narrowest width of 0.8 mm and a periodicity of 10 mm exhibits the highest net power improvement. However, excessive reduction in the narrowest width and shape variation period increases inlet pressure losses, ultimately degrading system net power.

In this study, a multiphysical field coupling model of metal hydride hydrogen storage reactor (MHHSR) based on cylindrical heat exchanger was established. The influence of the geometric shape and position of the cylindrical heat exchanger on the hydrogen absorption performance of the reactor was investigated, and the mathematical model was developed. The optimal position of the heat transfer structure was obtained, and the characteristics and intrinsic mechanisms of heat and mass transfer in the alloy bed during the hydrogen absorption process were explored. Additionally, based on the area of the temperature differential zones among different layers, the uniformity of heat transfer in multilayer beds was analyzed. The research results showed that when the embedded heat transfer ring was located at 0.62R of the alloy bed, the hydrogen storage reactor achieved 90% hydrogen capacity within the shortest time. By comparison to the central heat exchange tube structure and the external heat exchange jacket structure, there was a time reduction of 76.3% and 60.7%, respectively. Different types of heat exchanger structures caused differences in the thermal mass transfer characteristics of the alloy bed, which changed the evolution modes of the bed's reaction interface area and moving speed, ultimately affecting the reactor's hydrogen absorption performance. When multiple independent reaction bed layers existed in the reactor, a smaller temperature difference region area among different bed layers resulted in more uniform heat and mass transfer and higher energy efficiency of heat exchanger structures.

This paper studied the simulation of methanol synthesis from CO2 and green hydrogen, and proposed an indicator of the energy storage density of CO2. Then influences of multiple variables on the performance indicators were analyzed. The results show that the systematic energy efficiency and energetic yield of methanol increase with the increase in the electrolysis efficiency, per pass CO2 conversion rate, electrolysis pressure, and initial CO2 pressure. However, these indicators decrease with the increase in the methanol synthesis pressure. The variations of the energy storage density of CO2 with these variables are opposite to the systematic energy efficiency and energetic yield. The electrolysis efficiency and per pass CO2 conversion rate are the sensitive and key variables of this process. Under the optimal conditions, the systematic energy efficiencies based on the higher and lower heating values are 68.0% and 59.6%, respectively, the energy storage density of CO2 is 6.07 kWh/kg, and the energetic yield of methanol is 0.108 kg/(kW·h), indicating the powertomethanol system using CO2 as feedstock is unsatisfactory in term of systematic energy efficiency, but has significant advantage in the energy storage density.

To solve the problem of multitime scale power and energy imbalance in clean energyrich areas, this paper proposes a collaborative configuration method for seasonal and shortterm hybrid energy storage systems based on the principle of coconstruction and sharing on the power generation side. First, a crossseason sequential coupled operation model of the hydrogen energy storage system is established according to the seasonal output characteristics of hydropower. Second, a coupled operation mechanism of the hydrogenelectric energy storage system on the intraday time scale is proposed. A planning model for the hybrid energy storage system is developed to maximize the annual net income of the generation side after the system is configured. The nonconvex nonlinear programming model is converted into a mixed integer linear programming model. Then, the investment cost of the hybrid energy storage system is reasonably apportioned, considering the differentiated investment risks faced by different stakeholders on the power generation side. Finally, actual data from a region in Zhejiang Province is analyzed. The results show that the proposed method can effectively mitigate seasonal energy imbalance and intraday power imbalance in the region while ensuring the stability of cooperative energy storage system construction among stakeholders on the generation side.

Aiming at the optimal economic operation of energy management strategy for multi port configuration of AC/DC flexible interconnection system, this article proposes an optimization method for multi port AC/DC flexible joint energy control system based on improved Pelican algorithm, which is based on photovoltaic power generation curve, high fit between peak and valley electricity price ranges, and energy storage control. Construct an optimization model for a multi terminal oral DC flexible joint energy control system, with constraints on DC bus voltage, power control unit capacity, and power balance, to comprehensively consider the minimum network loss, optimal economy, and optimal energy storage charging/discharging state. Based on the Pelican optimization algorithm, the model constructed is solved by introducing random mass disturbance behavior to improve the global search ability of the algorithm and prevent the model from getting stuck in local optima during solution. After simulation verification, the method proposed in the article can achieve optimal scheduling of multi terminal oral DC flexible joint energy control system.

With the rapid penetration of new energy sources such as photovoltaic power generation, the power system has put forward higher requirements for its participation in primary frequency regulation, requiring it to support the power grid in a more flexible way. In order to achieve more comprehensive frequency regulation, the key indicators for evaluating frequency quality are first determined according to the relevant grid specifications. Then, with the help of the motion equation of synchronous generator rotor, the effects of the constant of inertia and damping gain on the frequency quality are analyzed. Based on these research results, a coordinated control strategy of virtual inertia and frequency damping is designed, aiming to achieve the optimal frequency support of photovoltaic system with a certain power reserve. Finally, the performance of the proposed control strategy is verified by simulation, and the advantages and effectiveness of PV system participating in primary frequency regulation are displayed. By coordinating between virtual inertial control and frequency damping control, photovoltaic systems can support the frequency stability of the grid in an efficient manner.

Renewablerich remote areas are facing problems such as high cost of external energy supply, low reliability of internal green micropower, high fuel transportation cost and environmental pollution caused by diesel generators as backup power sources, which is not meeting the needs of low carbonization. To solve those problems, this paper propses a design of microenergy network based on hydrogen energy storage in an offgrid hydrogen storage energy supply scenario. The framework for a hydrogenbased zerocarbon microenergy network on account of the spatial and temporal distribution characteristics of renewable energy in remote areas is presented. Furthermore, the paper proposes the resource endowment and operation constraints of the hydrogen based micro energy network, formulates operation strategies for energy surplus and shortage periods and carries out the case simulation. Simulation results of a village in Yunnan Province prove the feasibility of the proposed microenergy network and its operation strategies, which effectively eliminates the influence of unstable regional green micropower output and seasonal shortage on the reliability of the power supply system and reduces regional thermal load burden. Furthermore, it helps decarbonize the regional energy system. Research results provide a reference for energy consumption improvement and carbon reduction in renewablerich areas such as remote areas and islands.

Catalytic reforming of palm kernel shell (PKS) pyrolysis volatile matter was studied using char (Char) and activated carbon (AC) as catalysts under microwaveassisted heating. The impacts of different carbonbased catalysts on the composition of products were studied. The possible reaction pathways during catalytic reforming of PKS pyrolysis volatile matter under microwaveassisted heating were also investigated. During catalytic reforming of pyrolysis volatile matter, the catalyst promoted the yield of gas product, which led to the decrease of biooil yield. Compared with the Char, AC not only has higher catalytic activity to facilitate the conversion of biooil to gas, but also exhibited better selectivity for the formation of singlering aromatic compounds (especially phenol) in biooil. Using the AC catalyst, the concentrations of the singlering aromatic compounds reached 84.25%. The catalyst mainly promoted the secondary reactions such as demethoxylation reaction and dehydrocarbylation reaction.

In order to achieve good aerodynamic and structural performance of wind turbine airfoils simultaneously, an integrated optimization method for aerodynamic shape and internal topology of airfoils is proposed. The airfoil aerodynamic shape is represented using the Hicks Henne type function, and its aerodynamic performance is calculated by using XFOIL. A finite element model of the airfoil is established by using ANSYS, and the structural topology performance is computed. Based on this, a MATLAB program is developed by using a genetic algorithm with the objectives of maximizing the lifttodrag ratio and minimizing the compliance. Five basic airfoils of a 1.5 MW wind turbine blade are optimized under 3 objective weight factors, and the results showed that compared to the initial airfoils, all optimized airfoils exhibit increase in maximum lifttodrag ratio and decrease in structural compliance. At the same time, basically consistent internal structural conceptual design solutions are obtained with the spar caps on the upper and lower surfaces offset towards the leading and trailing edges, respectively. A comparison is made between the new blade using the optimized airfoils and the original blade, and the results indicate that the application of optimized airfoils combined with minor main spar caps offset, the aerodynamic and structural performance of the blades could be effectively improved.