Solar-driven low-rank coal gasification technology offers both significant carbon reduction potential and the capability to store intermittent solar energy. Enhancing the efficiency of solar-to-fuel energy conversion remains the core bottleneck for large-scale application of this technology. The unclear structural evolution mechanism of pyrolytic coke under high-intensity irradiation has constrained the optimization of solar reactors and the improvement of efficiency. This study combined in-situ online gas analysis and ex-situ characterization of coke physical-chemical structure to systematically reveal the coke evolution mechanism during solar pyrolysis and its impact on the reaction reactivity for further gasification. Compared to conventional pyrolysis, excessively rapid heating rates of the initial solar pyrolysis result in reduced stacking height and increased interlayer spacing, impeding the orderly stacking of coke microcrystals. This process leads to the formation of a coke structure rich in mesopores with high gasification reactivity. The effects of the later pyrolysis stage at the macroscopic and microscopic levels are illustrated as the destruction of the coke pore structure and the enhancement of lateral growth in the aromatic ring system, respectively. This conversely reduces the gasification reactivity, with both the surface area and pore volume decreasing. As heat flux density increased, the gasification reactivity of coke first rose and then decreased. It was determined by the competitive effects between the development of active porous structures in the initial pyrolysis and the later evolution of inert ordered structures under high heat flux density. This study establishes a theoretical foundation analysis of the gasification mechanisms of solar-driven low-rank coal.

This study aims to investigate the influence of the thermochemical conversion behavior of microalgae pellet in molten hydroxide salts(80％NaOH-20％Na2CO3)on hydrogen production.By comparing the temperature evolution,gas release characteristics,and structure evolution of pellet with and without molten salt,and combining with char alkalization experiments,the regulatory mechanism of molten salt on the reaction pathways and hydrogen production behavior of microalgae pellet was systematically analyzed.The results indicate that the molten salt significantly enhances the internal heat transfer efficiency of the pellet,with a central heating rate reaching 177 ℃/s,effectively alleviating thermal hysteresis.Meanwhile,the molten salt promoted pellet pore development through penetration,erosion,and catalytic effects,resulting in a porosity increase of 53.2％-104.3％after 10 s of reaction.It also significantly enhanced the conversion efficiency,with the dominant reaction pathway shifting to char gasification after only 70 s.Furthermore,when the heating rate was increased above 600℃,the hydrogen yield from char alkalization improved more markedly,primarily attributed to the synergistic promotion effect of the molten salt's catalytic effect and the rapid heating process on the volatiles reforming.This study provides a theoretical foundation for a deeper understanding of the mechanisms behind efficient hydrogen production from biomass in molten hydroxide salts.

Hydrogen production from microalgae represents a sustainable alternative to fossil fuel-based methods. However, conventional thermochemical routes face challenges such as inadequate hydrogen yield/purity and persistent tar formation. This study proposes a novel integrated process for hydrogen production by thermochemical conversion of microalgae in molten hydroxide, which uniquely incorporates critical yet understudied ash removal and salt regeneration units. A rigorous, experimentally validated Aspen Plus model was developed to simulate the entire process. Operating at 750 degrees C with a microalgae feed rate of 1000 kg/h, the process produces 110.5 kg/h (equivalent to 30 mmol/g ash-free feedstock) of high-purity hydrogen (99.99%) with an energy conversion efficiency of 41.67%, which can be elevated to 46.57% by optimizing the ash removal strategy. Techno-economic analysis indicates a levelized cost of hydrogen (LCOH) of 35.07 CNY/kg, making it competitive among advanced thermochemical routes for microalgae conversion. Sensitivity analysis identifies feedstock cost as the most influential parameter. The LCOH can be significantly reduced to 15.45 CNY/kg when microalgae are priced at lignocellulosic biomass levels, which outperforms methane reforming/cracking with CO2 capture. These findings confirm the techno-economic viability of the molten hydroxide technology, highlighting the crucial role of feedstock sourcing and operation optimization in accelerating the commercial implementation.

Alkaline thermal treatment is a promising route for H2 production from algal biomass, offering high H2 yields under mild conditions, in situ capture of CO/CO2, and direct processing of wet algal biomass. However, the H2 formation pathways of the major biochemical components during alkaline thermal treatment are still poorly understood, which hinders the rational optimization of this process for hydrogen production. In this study, carbohydrate-rich, protein-rich, and lipid-rich algae were used as representative feedstocks to elucidate how the major components govern hydrogen production. The results showed that lipids were the most favorable fraction for H2 production, with the lipid-rich feedstock achieving the highest H2 yield of 35.90 mmol·g-1 at 600 °C. The three major components exhibited distinct temperature-dependent H2 release. Carbohydrates contributed mainly to the earliest H2 release through dehydration, cleavage, and dehydrogenation of oxygen-rich structures. Proteins showed the most intense H2 release between 330 and 350 °C, accompanied by significant CH4 formation, which was mainly attributed to cracking and dehydrogenation of protein-derived intermediates. In contrast, lipids showed a delayed main H2 peak at 410 °C. Above 450 °C, lipids further dominated H2 formation through the stepwise conversion of unsaturated intermediates, long-chain intermediates, and residual char. These findings offer mechanistic guidance for feedstock selection, process optimization, and the rational design of efficient algal alkaline thermal treatment systems.

The thermochemical conversion of microalgae in molten hydroxides presents a promising pathway for sustainable hydrogen production, distinguished by high hydrogen yield and minimal tar formation. However, the underlying reaction network governing these advantages remains unclear. To address this, a multiscale analysis was employed to unravel the enhancement mechanisms. This integrated approach combined macro-scale observation using coupled thermogravimetric-Fourier transform infrared spectroscopy-mass spectrometry (TG-FTIR-MS), mesoscale validation via targeted experiments with model aromatics and pyrolytic char, and microscale elucidation through density functional theory (DFT) calculations. Results reveal that molten hydroxides simultaneously lower the biomass decomposition temperature, suppress tar formation, and activate three distinct hydrogen production pathways: organic catalytic cracking (200-450 °C), deep aromatic volatiles reforming (>500 °C), and char alkalization (>550 °C). Aromatics reforming involves both condensation and ring cleavage. Ring cleavage proceeds via OH- nucleophilic addition and C-H bond heterolysis, with deprotonation as the rate-determining step and the energy barrier governed by the molecular geometry of aromatics. Char alkalization follows fundamental steps with lighter aromatics but encounters higher energy barriers due to its more condensed structure. This work establishes a multiscale mechanistic framework for hydrogen production, paving the way for the rational design of efficient and low-carbon biomass-to-hydrogen technologies based on molten salts.

This study extensively analyzed the characteristics of landfill leachate treatment systems for the comparison and evaluation of design schemes. The analysis was based on two design schemes related to the landfill leachate treatment system in Hangzhou. Additionally, a fuzzy comprehensive evaluation model for landfill leachate treatment system design schemes was established, considering the three target levels of safety, reliability, and economy. The evaluation factors for the target and attribute layers were proposed after a thorough analysis. The weight coefficients for the target, attribute, and scheme layers were determined using the fuzzy comprehensive evaluation model based on a questionnaire survey of experts. The evaluation results indicated that the design scheme involving an oxidation ditch outperformed the UNITANK design in the landfill leachate treatment system. Compared with the actual engineering cases, scheme A1 was better than scheme A2. For other similar qualitative and difficult to quantify the selection of the program, it could be evaluated with the help of fuzzy comprehensive evalution model. The inclusion of multiple factors in the target and attribute layers increased the complexity of the calculation process but enhanced the accuracy of the results. The method of transforming qualitative schemes into quantitative ones, as presented in this study, is not only practical, but also widely applicable.

The kinetic analysis of thermochemical conversion of carbonaceous materials in molten salts is difficult due to the difficulty in obtaining the weight loss characteristics of the feedstock. The novel reducing charge demand (RCD) method is proposed to solve the challenges of molten salt transformation and gas absorption that affect the feasibility and accuracy of traditional analysis methods. The pyrolysis characteristics of algae with different pellet sizes in alkaline molten salts are investigated, and the related kinetic mechanisms are revealed by combining the RCD method and the temperature distribution inside the pellets. Results show that the higher temperature for smaller pellets slightly increases the hydrogen yield/purity. At 750 degrees C, the hydrogen yield reaches 72.44 mmol/g with carbon capture efficiencies of 69-73%. The pyrolysis starts with algae catalytic pyrolysis (random scission model) and then begins to be dominated by char alkalization (second-order model) at conversion efficiencies of 50-60%. The average activation energy of both stages is reduced by the molten salts to 31.88-35.61 and 56.60-59.69 kJmol-1. This study provides a powerful method to explore the kinetic mechanism related to the molten salt system and guide the optimization of the hydrogen production technology.

Latent heat thermal energy storage (LHTES) has been recognized as a viable method to tackle the intermittency of renewable energy. However, the low thermal conductivity of phase change material (PCM) limits its development, especially in large-scale applications when concerns are economical. Thus, the current study proposed a concept of growing fins, which accumulatively conducted the structural designs of fins based on economic evaluation to improve the thermal and economic performance of large-scale LHTES. The multilayer interacted characteristic region method was applied to characterize the melting behaviours of growing fins, and the established 2D numerical model for shell-and-tube LHTES was experimentally validated. With this 2D model, the effect of growing strategies on the natural convection and dead zone was effectively discussed. The full melting time and the economic efficiency of the horizontal and vertical growing fins were comprehensively evaluated. The LHTES unit with optimal growing fins exhibited a 61.78 % reduction in melting time compared to the initial structure. Meanwhile, the economic performance of the optimal unit, evaluated as the melting rate per unit material cost, increased by 38.55 %. Generally, the growing fins strategy could tap the cost-effectiveness of added enhancement materials, promoting future products and industrialization of large-scale LHTES.

Pyrolysis in alkaline molten salts provides a promising approach for efficient hydrogen production from carbonaceous feedstocks. However, molten salts react with inorganics inherent in feedstocks like biomass and organic solid waste, which in turn affects the organics conversion. The effect of inorganics on the conversion of feedstock and molten salts has not been adequately studied, which is indispensable for the practical operation of molten salt technologies. This study firstly provides insights into the transformation of molten NaOH-Na2CO3 and changes in the physicochemical properties of molten salts under the influence of biomass inorganics by experiments and simulations. Results reveal that ionic bond breaking/reorganization, eutectic salts melting and precipitates dissolution occur sequentially between the inorganics and the molten salts, forming stratification and suppressing hydrogen production. Molten salts form new eutectic salts with NaCl/KCl/SO42-/SiO2 addition, while Mg2+ and Ca2+ are converted into MgCO3/Mg2Cl(OH)(3) and CaCO3 precipitates. Inorganics inhibit the hydrogen production in the order: Ca2+ > Mg2+> K+ > Na+ and SO42- > SiO32- > Cl-. To overcome the stratification and deactivation of molten salts, an innovative green regeneration method is proposed. Under the optimized parameters, the NaOH recovery is 98.14 %, the purity is 97.69 % and the hydrogen production reaches 69.56 mmol/g-biomass.

In response to global environmental concerns and rising energy demands, this study evaluates photovoltaic (PV) technologies for designing efficient building rooftop PV systems and promoting sustainable energy integration. The research combines weather data from NREL and NASA to enhance the precision of performance analysis using PVsyst software, adhering to IEC-61724 standards. This dual-source approach ensures a robust assessment of PV system reliability across diverse climates. Building rooftop installation capacities are evaluated with PVSOL software, while HOMER Pro performs system configuration analyses. Results indicate that monocrystalline silicon (m-Si) outperforms polycrystalline silicon (p-Si) and thin-film technologies, Specifically, m-Si achieves an annual array yield of 5.61 kWh/kWp/day and 5.37 kWh/kWp/day, final yields of 5.47 kWh/kWp/day and 5.24 kWh/kWp/day, capacity factors of 17.9 % and 17.2 %, and performance ratios of 84.3 % and 86.7 %, respectively. Strategic building rooftop PV planning, taking into account roof area, tilt angle, and spacing, identifies an optimal capacity of 0.05 kW/m2. HOMER Pro recommends a grid-connected 5.03 kW PV system with a 4-kWh battery and 3.54 kW inverter, achieving a cost of energy (COE) of USD 0.0465/kWh. Sensitivity analysis reveals that higher solar irradiance reduces energy costs, while increased electric loads raise them. This study introduces a novel methodology for integrating dual-source weather data and advanced software tools to evaluate and optimize PV systems, providing practical insights for sustainable building rooftop PV installations and advancing renewable energy solutions.

To achieve the rational development and utilization of water resources in energy development bases and sustainable economic and social development, research is conducted on the control method of water resource consumption in energy development bases based on the law of energy-water correlation. Using Internet of Things technology to collect water resource consumption data from energy development bases, based on the results of data collection, taking Shanxi Coal Development Base as the research area, based on the objective relationship between energy and water, a multiregion input-output model and linear programming model are established, with objective functions and constraints set to achieve water resource consumption control in energy development bases. Under the dual constraint scenario of energy conservation and water conservation, the optimization effect of the industrial structure of the water resource carrying capacity level in the research area is explored. The outcomes show that the water resource in the research area can bear 1,949.58 billion Yuan for 22.0336 million people. The water resources holding capacity is at the general level. Based on the limitations of energy consumption, raising the share of the mining sector and decreasing the share of the industrial and commercial service sectors can minimize the overall consumption of energy and water resources while ensuring the growth of the local economy. Reducing the extent of agricultural expansion supports both water conservation and regional economic growth because water resource consumption is constrained. A clear difference in the production and utilization effect of energy resource per unit will result from the direction difference in structural adjustment of the mining industry, which is based on the dual restrictions of energy-water resource.

The high proportion of new energy grid connection has put forward higher requirements for the flexible regulation capability of the power system. As the main flexible regulation power source in China, thermal power should contribute more flexible regulation potential to serve the grid connection of new energy. However, the regulation potential of thermal power units is currently facing depletion. Using energy storage systems to assist thermal power units in secondary frequency regulation (AGC regulation) can significantly improve the regulation performance of the units and provide more flexible regulation resources for the power system. This article first proposes an energy storage system access scheme, which can not only improve the AGC regulation performance of the unit, but also ensure stable operation of the high power plant transformer after access, without affecting the normal operation of the original equipment in the power plant; Establish a model for the combined frequency regulation system of thermal power units and energy storage, propose calculation indicators for AGC regulation performance, and demonstrate the effectiveness of the evaluation method through simulation. The evaluation results indicate that the AGC regulation rate, regulation accuracy, and response time indicators proposed in this paper can effectively represent the AGC regulation performance of the unit. Simulation results show that energy storage systems can compensate for the shortcomings of thermal power units, and adding energy storage systems can greatly improve the regulation performance of the unit.

The requirement for primary frequency regulation (PFR) capability of thermal power plants (TPPs) in power systems with larger penetration of renewable energy resources (RESs) is higher since the RESs contribute less to PFR compared with TPPs. To ensure the system frequency stability, this paper proposes to enhance the PFR capability of TPPs through integrating energy storage systems (ESSs) into them. By applying the PFR control strategy to the ESS, the fast response capability of the ESS is utilized, and the overall response speed of the power plant integrated with an ESS can be significantly improved. Furthermore, the state of charge (SOC) of the ESS is kept within the permissible range during the operation by adopting an energy recovery strategy to restore the released energy for PFR periodically. The effectiveness of the proposed control strategy is verified by simulation results.

As a commonly used control system, main steam temperature control has the characteristics of large inertia and large lag, and the noise interference it receives can also have a significant impact on the system. Faced with controlled objects with large inertia and delay, traditional control methods based on feedback regulation are difficult to quickly adjust the system, and it is also difficult to identify and control disturbances in advance. At the same time, although using feedforward control based on inverse models can quickly regulate the system, the strong differential effect caused by its sensitivity to high-frequency noise can lead to a decrease in regulation quality, so a feedback channel needs to be designed to address the impact of noise. This article introduces the basic principles of feedforward control, feedforward tracking control, and active disturbance rejection control, and points out areas for improvement. On this basis, a feedforward tracking control algorithm for main steam temperature with disturbance suppression is proposed. Through simulation experiments, its characteristics were analyzed and its control effect, anti-interference ability, and robustness were verified.

Microalgae pyrolysis in molten salt is a promising way to produce high-quality bio-oil. This study provides deep insights into the characteristics of nitrogen-containing compounds (NCCs) during protein-rich spirulina platensis pyrolysis in a ternary eutectic carbonate (Li2CO3-Na2CO3-K2CO3) at different temperatures (450-600 degrees C). The results indicate that the molten carbonate significantly reduces the NCCs contents in bio-oil and heavy bio-oil by 25.89 % and 62.38 % respectively, which is due to the intensified removal of nitrogenous functional groups (C-N, C-N of the primary amide, and C---N) in NCCs. The molten carbonate also intensifies the direct cleavage of amino acids and the conversion of amides/amines to form nitrile compounds but inhibits the dehydration of hexadecanamide to form hexadecanenitrile in bio-oil light components. Concerning the heavy components in bio-oil, molten carbonate intensifies the depolymerization of NCCs and plays an important role in intensifying the cyclane ring opening, double bond breaking, and cleavage of a benzene ring of NCCs. Finally, the possible pathways for nitrogen evolution in bio-oil are proposed, which can provide guidance for the high-quality bio-oil production by molten salt pyrolysis of algae.

Using wide area branch information can mine the out-of-step oscillation characteristics, and identify the true vertical-foot-voltage drop point in actual power grid. For the large-scale power grid, it is practical significance for the discrimination of dominant instability mode and the grid disassociation control. Firstly, basing on the equivalent double machine model, the issue of false vertical-foot-voltage drop point during out-of-step oscillation can de described, and the causes of its drop point are discussed. Secondly, using the voltage vector diagram, the relationship between vertical-foot-voltage drop point position and branch power can be analyzed, so as to obtain the constraint of the vertical-foot-voltage drop point within the branch head and end power. Finally, considering the influence of the ground capacitance and the non-coherence factors in the group, a criterion for identifying the true vertical-foot-voltage drop point is proposed, and the validity of the proposed criterion can be verified by the simple double machine system.

Biomass pyrolysis within the alkaline molten salt is attractive due to its ability to achieve high hydrogen yield under relatively mild conditions. However, poor contact between biomass, especially the biomass pellet, and hydroxide during the slow heating process, as well as low reaction temperatures, become key factors limiting the hydrogen production. To address these challenges, fast pyrolysis of the algae pellet in molten NaOH-Na2CO3 was conducted at 550, 650, and 750 °C. Algae were chosen as feedstock for their high photosynthetic efficiency and growth rate, and the concept of coupling molten salt with concentrated solar energy was proposed to address the issue of high energy consumption at high temperatures. At 750 °C, the pollutant gases containing Cl and S were completely removed, and the HCN removal rate reached 44.92%. During the continuous pyrolysis process, after a slight increase, the hydrogen yield remained stable at 71.48 mmol/g-algae and constituted 86.10% of the gas products, and a minimum theoretical hydrogen production efficiency of algae can reach 84.86%. Most importantly, the evolution of physicochemical properties of molten NaOH-Na2CO3 was revealed for the first time. Combined with the conversion characteristics of feedstock and gas products, this study provides practical guidance for large-scale application of molten salt including feedstock, operation parameters, and post-treatment process.

The AC charging pile is the main energy supply facility for household electric vehicles, which uses a vehicle mounted charger to charge the power battery. The current standard of the State Grid Corporation of China clearly stipulates the function of the AC charging pile and does not take into account the impact of the harmonics of the vehicle mounted charger on the power grid. Therefore, in view of the deficiency that AC charging piles cannot suppress the current harmonics of the vehicle mounted charger, application of the active power filtering technology to the design of AC charging piles is proposed to form a new type of AC charging pile with better functions. In the experimental prototype that was built, for vehicle mounted chargers with two load characteristics, the composite control method of traditional PI control and repetitive control is adopted, where the new AC charging pile effectively suppresses the harmonics of the vehicle-mounted charger. Experiments show that the AC charging pile using active power filtering technology cannot only improve the power quality of the grid side but also reduce the impact of harmonics on the power metering and billing system, ensuring the stability of the charging communication system.

Ground potential work robots equipped with dexterous arms can be used to replace manual overhead power distribution operations, but there are still many challenges in the load and control stability of the dexterous arms of ground potential work robots. In order to solve the problems of control stability of the dexterous arm of the geopotential work robot, an adaptive PD control method of the dexterous arm equipped with a gravity balance mechanism is proposed. Firstly, by establishing and analysing the dexterous arm model, the gravity compensation device is set in the first two sections of the dexterous arm. Secondly, the controller model is designed and a Lyapunov function is defined to prove the asymptotic stability of the closed-loop system. Thirdly, the adaptive control architecture of the dexterous arm of the ground potential energisation robot is constructed in MATLAB to test the ability of the controller to suppress the load perturbation, and finally, the effectiveness of the methodology of this paper is verified by integrating and analysing the data of the PD control step-signal response velocity and the gravity-balance-based adaptive PD control step-signal response velocity.