ISSN 2095-560X
CN 44-1698/TK
CONDEN XJIIA8
CN 44-1698/TK
CONDEN XJIIA8
Biomass resources, being carbon-neutral, serve as an excellent energy fuel. Traditional methods of biomass gasification to produce syngas involve the water-gas shift reaction, followed by separation and purification processes to achieve high concentrations of syngas and hydrogen. However, these processes are intricate and complex. The chemical looping gasification and reforming of biomass for hydrogen production represent a novel technology in syngas and hydrogen preparation. Based on Aspen Plus software, hydrogen production from biomass chemical looping gasification reforming was studied, using pine biomass and steam as feedstock, and syngas and hydrogen as final products, combining process simulation and sensitivity analysis to explore the influence of key parameters on system performance and obtain maximum hydrogen/synthesis gas yield. Based on the Gibbs reactor, we simulated the product fractions and state parameters of the reactants in the fuel reactor, hydrogen reactor, and air reactor of the biomass chemical looping gasification reforming process for hydrogen production under the conditions of satisfying phase equilibrium and chemical equilibrium. Through the sensitivity analysis and thermodynamic analysis of the key parameters, the optimal operating conditions and operating parameters were determined as follows: fuel reactor temperature of 800 °C, oxygen carrier to biomass ratio of 0.4, water vapor (steam) to biomass ratio of 1.36, hydrogen production reactor temperature of 600 °C, air to biomass ratio of 0.57. The syngas gas yield is 0.98 m3/kg, the H2 yield is 0.025 kg/kg, and the system's exergy efficiency is 68.06%. Based on the simulation analysis, it is demonstrated that the biomass chemical looping gasification reforming system for hydrogen production not only obtains higher yield syngas and high-purity hydrogen, but also realizes the system self-heating. The constructed biomass chemical looping gasification reforming hydrogen production system will provide the necessary basis and information for the optimized design of the key technologies of the subsequent processes and the larger-scale engineering demonstration.
Supercapacitors are considered to be one of the most ideal energy storage devices for their advantages of fast charging and discharging, good stability and long lifetime. Biomass-derived carbon with a certain pore structure and electrical conductivity is suitable as supercapacitor electrode material. The development of biomass-based supercapacitor carbon materials is an important way to achieve high-value-added use of biomass energy and energy sustainability. Based on the storage principle, supercapacitors are classified into electric double-layer capacitors and pseudocapacitors. Firstly, the preparation strategies of biomass-derived carbon as electrodes for electric double-layer supercapacitors are introduced from aspects such as biomass selection and pretreatment methods, with a focus on the carbonization methods, activation means of biomass and their pore-forming principles. Subsequently, the surface modification means of carbon materials are described, focusing on the advantages of coupling biocarbon and pseudocapacitor electrode materials to form a composite material as well as the preparation method. Finally, the challenges and future perspectives of preparing supercapacitor carbon materials from biomass are presented in the light of current research.
LiMn2O4 batteries have been widely used in the field of power batteries due to their advantages of high safety and low cost, but their cycling stability at high temperature remains a major challenge. A novel amine-functionalized trisiloxane electrolyte additive, [3-(N,N-dimethylamino)diethoxypropyl]heptamethyltrisiloxane (MTSON), is designed and synthesized to enhance the high-temperature performance of LiMn2O4 batteries. By using 0.5% MTSON, the capacity retention rate of LiMn2O4/Li cell increases to 95.2% after 200 cycles at 55 ℃ and 1 C rate, compared to 92.6% for the base electrolyte. X-ray photoelectron spectroscopy shows that MTSON could construct a stable cathode electrolyte interface film on the surface of the LiMn2O4 electrode. At the same time, MTSON additive inhibits the hydrolysis of LiPF6 salts in the electrolyte, and the dissolution amount of manganese ions in LiMn2O4/Li cells is reduced by nearly 80% after 200 cycles at 55 ℃. This work shows that MTSON is a promising electrolyte additive to improve the high-temperature performance of LiMn2O4 batteries.
Lithium-sulfur batteries (LSBs) are considered as one of the most promising candidates for next-generation energy storage systems due to their exceptionally high theoretical specific capacity of up to 1 675 mA∙h/g, low cost, and environmental friendliness. However, their practical application is hindered by several challenges, such as the low conductivity of sulfur and its discharge product Li2S, the severe shuttle effect of lithium polysulfides (LiPSs) during charge-discharge cycles, and sluggish sulfur redox reaction kinetics. These issues lead to irreversible sulfur loss, low Coulombic efficiency, and poor cycling stability in LSBs. To address these challenges, a simple and effective synthesis strategy was developed. By employing a one-step hydrothermal method combined with high-temperature partial phosphidation and leveraging the strong reducing properties of NaBH4, a VP-MoP/MoO2@MXene heterostructure catalyst containing phosphorus vacancies was successfully synthesized. This catalyst was applied as a cathode material in LSBs. The presence of phosphorus vacancies effectively modulates the local charge states of adjacent phosphorus atoms in the defect regions, generating more catalytic active sites. This enhances the adsorption of LiPSs and promotes their catalytic conversion, significantly suppressing the polysulfide shuttle, improving sulfur utilization, and accelerating the bidirectional redox kinetics of sulfur. Consequently, the S/VP-MoP/MoO2@MXene cathode delivers an initial specific capacity of 967 mA∙h/g at 1 C and maintains a reversible capacity of 574 mA∙h/g after 300 cycles, corresponding to an average capacity fade of only 0.13% per cycle. More importantly, under high sulfur loading (6.0 mg/cm2) and lean electrolyte (4.5 μL/mg) conditions, the S/VP-MoP/MoO2@MXene cathode exhibits outstanding initial areal capacity (5.57 mA∙h/cm2) and excellent cycling stability. These results provide theoretical guidance and practical references for the design of efficient bidirectional catalysts in LSBs.
In the combustion process of mixed biomass in coal-fired boilers, the direct discharge of a large amount of high-temperature flue gas not only pollutes the environment but also causes huge energy loss due to the ineffective use of flue gas waste heat. This paper proposes adding a spiral twisted tube heat exchanger at the tail of the flue to recover the residual heat of the flue gas and reduce the exhaust temperature to improve the energy utilization efficiency. A numerical simulation of the coupled heat transfer process of the shell convection condensation of the spiral twisted tube heat exchanger is carried out. The heat transfer and resistance characteristics in the shell of a spiral twisted tube heat exchanger under different working conditions are simulated. The results show that the increase in flue gas temperature promotes the convective part of the entire convection-condensation coupled heat transfer process. The rise of Reynolds number (Re) benefits sensible heat exchange of flue gas but is unfavorable for condensation latent heat exchange. The increase of water vapor content has a positive effect on latent heat exchange, but has little impact on sensible heat exchange. Under the conditions of inlet flue gas temperature of 353.15 K to 433.15 K, Re of 9 000, and water vapor content of 18.6%, the spiral twisted tube heat exchanger has the best economic performance in enhancing heat transfer, significantly outperforming the circular tube condensing heat exchanger.
The dissociation characteristics of natural gas hydrate-bearing fine-grained soil hold critical implications for the safe and efficient exploitation of hydrate reservoirs. A self-developed hydrate-bearing sediment dissociation test apparatus was utilized to conduct depressurization exploitation experiments on methane hydrate-bearing fine-grained soils, with controlled variables including hydrate saturation, production pressure differential, and ambient temperature. The test results show that the minimum temperature of the reservoir is mainly affected by the production pressure difference during the depressurization process. A higher production pressure difference is beneficial to obtain a higher peak gas production rate, but the gas production rate in the later stage of depressurization is only affected by the hydrate dissociation rate, and the high production pressure difference has no gain effect on the gas production rate. During the depressurization, the main factors affecting the gas production behavior of hydrate reservoirs are the production pressure difference, followed by the initial hydrate saturation, and finally the ambient temperature. The research results have guiding significance for the safe and efficient exploitation of natural gas hydrate.
With the continuous increase in global carbon emissions, developing efficient CO2 separation and capture technologies has become an urgent task. Imidazole-based ionic liquids, due to their excellent CO2 absorption performance, have shown good application prospects in hydrate-based gas separation (HBGS) technology and are widely used as performance-enhancing additives for this technology. This study aims to explore the influence of imidazole-based ionic liquids on the kinetic characteristics of hydrate formation in binary mixtures of CO2/N2 (at two different ratios) under different temperature conditions. The experiment used 1-butyl-3-methylimidazolium octyl sulfate ([BMIM][OS]) as an additive to study the formation kinetics process of CO2/N2 mixed gas hydrate, and quantitatively evaluated the gas separation performance of this method. The results show that compared with the pure water system, [BMIM][OS] ionic liquid can effectively promote the formation of gas hydrates. Under the condition of 277.15 K, the CO2 consumption in the system 1 (the molar ratio of CO2 to N2 is 0.5/0.5) increased by 108%, while the CO2 consumption in the system 2 (the molar ratio of CO2 to N2 is 0.8/0.2) increased by 21.1%. The consumption of CO2 and N2 decreases with the increase of experimental temperature. At 273.15 K, for the system 1, the CO2 separation factor reaches 0.37. For the system 2, the CO2 separation factor reaches 0.44. The maximum unit gas consumption for both the system 1 and the system 2 is 0.025 mol/mol. [BMIM][OS] Ionic liquids improve the mass transfer process and increase the consumption of CO2. The results of this study provide reference for CO2 gas separation and capture.
To alleviate the increasingly serious energy crisis and improve the utilization efficiency of biomass resources, gasification, as an important means of thermochemical conversion technology, is considered to be a hydrogen production technology from biomass with great potential. This paper summarizes the principle of biomass gasification, describes the chemical reaction mechanism in the process, discusses the effects of gasification agent, temperature, pressure and catalyst types on the green hydrogen production process, comprehensively analyzes the existing problems and improvement methods in the hydrogen production technology from biomass gasification. The ideas for the source and preparation technology of green hydrogen are provided.
The wave glider is an unmanned surface vessel that relies on wave power for propulsion and solar energy for observation power. A new type of wave energy powered glider has been developed to address the shortcomings of traditional wave gliders, such as insufficient power in overcast and small wave conditions. It utilizes wave energy for propulsion while generating electricity and storing it in adverse conditions. This paper introduces the new wave glider's structure, working principle, and design, and presents a small-scale physical model and experimental results. The experimental results show that the designed wave energy powered glider can transform wave energy into mechanical work while cruising continuously. Under the specified wave conditions, the maximum output power of the glider is 529.8 mW. At sea, as the wave height and period increase, the power take-off power gradually increases, while the forward speed of the wave glider shows a trend of increasing initially and then decreasing. Test results preliminary validation confirms the feasibility of the proposed approach and provides a reference for subsequent experiments and applications.
It is the development trend of marine renewable energy research to make full use of offshore floating platforms, develop wave energy, wind energy, and solar energy, and realize comprehensive utilization of marine renewable energy through multi-energy complementarity. Domestic and international scholars have conducted research in the field of integrated utilization of offshore renewable energy. They have developed various joint plants, including wave-wind, wave-photovoltaic, and wind-photovoltaic, as well as other related technologies, yielding some promising results. Given the typical characteristics of renewable energy, such as intermittence, randomness, and volatility, wave power, wind power, and photovoltaic power all exhibit these traits. However, the complementary relationship among these energy sources and the current status of multi-energy complementary integration platform technology have not been comprehensively discussed. This paper examines the current research status, introduces the characteristics of floating offshore wave power, wind power, and photovoltaic power, and investigates the spatial and temporal relationship between these three marine energy sources at the same location. The findings of this study can provide insights and reference for the overall planning, detailed design, modeling, research, and construction of integrated platforms for wind power, photovoltaic power, and wave energy generation, as well as their coordination and control through multi-energy complementarity.
Geothermal energy stands out as a promising low-carbon energy source under the dual-carbon goals. In recent years, the rapid development of artificial intelligence (AI) technology has empowered the geothermal industry through its integrated applications, drawing significant attention and having a profound impact. This paper systematically summarizes the latest advancements and achievements of AI technology in various stages of geothermal exploration, development, and utilization. It is observed that AI technology is gradually extending its applications to various technical directions within the geothermal industry. With the continuous evolution of new-generation AI technologies, the integration of AI and geothermal energy will accelerate further, promoting the development and utilization of geothermal resources towards real-time allocation, dynamic adjustment, and multi-system collaboration. It is anticipated that within 8-10 years, an integrated intelligent complex encompassing geothermal exploration, development, and utilization will be established, forming a closed-loop intelligent system for the entire industry chain of geothermal energy. This will lead to a new pattern of complementary and synergistic development and efficient utilization of geothermal and multiple energy sources.
Poly(butylene succinate-cobutylene furandicarboxylate) copolyester (PBSF) with different alcohol-acid molar ratios was synthesized by direct esterification using 2,5-furandicarboxylic acid, 1,4-succinic acid, and 1,4-butanediol as raw materials, tetrabutyl titanate as catalyst, and triphenyl phosphite as stabilizer. The structure of polyesters was characterized by nuclear magnetic resonance hydrogen spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, and the results showed that the feedstock alcohol-acid molar ratios had less influence on the structure and crystalline structure of PBSF. The chain structure of PBSF was mainly dominated by the PBF chain segments that contained a rigid ring. PBSF exhibited typical thermoplastic elastomer characteristics; its glass transition temperature (0.27-6.81 °C) was lower than room temperature. Moreover, PBSF showed good thermal stability, with an initial thermal decomposition temperature higher than 347 °C. The tensile test results indicate that the alcohol-acid molar ratios of the raw material have a large influence on the mechanical properties of PBSF. The Young's modulus, the tensile strength, and the elongation at break decreased and then increased with the alcohol-acid molar ratios of raw material. The best tensile properties of PBSF-2.50 are obtained when the alcohol-acid molar ratio of raw material is 2.50, with tensile strength and the elongation at break of 19.93 MPa and 932.94%, respectively. Therefore, PBSF can be used as thermoplastics, as well as elastomers or impact modifiers.
The amount of power consumption in Guangdong province has long ranked first among all provinces in China. Analysis of the driving factors and their contribution to carbon emission in the power industry will provide theoretical support for establishing proper emission reduction paths for regional low-carbon development. In this study, the Kaya-LMDI model was used to decompose the influencing factors that contribute to carbon emission in the power sector from the perspectives of power generation and consumption. Based on data from 2010 to 2022, the driving effects and contribution breakdown of various factors to the changes in carbon emissions in the power industry were analyzed and discussed. Using the main influencing factors obtained, the growth rate of regional gross domestic product (GDP) is set as the main factor affecting the growth of carbon emissions in terms of social development scale. The factors of coal consumption intensity of coal-fired power generation, the proportion of coal-fired power in total power supply, the proportion of industrial gross value added in GDP, and industrial electricity consumption per unit of GDP are set as the main factors in terms of the power carbon emission reduction approach. Three levels of social development scale and three levels of emission reduction approach were combined and formed into nine developing scenarios in the power sector. By predicting the carbon emissions of the power industry in Guangdong province before 2060 under various scenarios, the driving effects of each influencing factor on the changes in carbon emissions in typical scenarios were compared and analyzed. It was found that carbon emissions in the power industry in Guangdong province are expected to peak in 2025 or 2030 in the three medium-speed social development scenarios. Among them, the scenario with medium-speed social development scale and medium-level emission reduction approach is relatively suitable for the future development of Guangdong's power industry. Under this scenario, electricity consumption is projected to reach 941 billion kW∙h in 2025 and 1 246.8 billion kW∙h in 2030.
