Yantao Yang

The advantages of torrefaction preheating, including the production of a hydrophobic solid product, improved particle size distribution, enhanced fuel properties with fewer environmental issues, decreased moisture content, and reduced volatile content. In order to meet the technical requirements of biomass oriented value-added and energy saving and emission reduction, pine sawdust (PS) was taken as the research object, and the physicochemical properties of the PS samples preheated at a low temperature were analyzed by synchronous thermal analysis (TG-DSC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and organic element analyzer (EA). The effect of preheating at a lower temperature on the physicochemical properties of PS was discussed. The results showed that, under the preheating condition of 200 °C, compared with PS, the water content of PS-200 decreased by 3.23%, the volatile content decreased by 3.69%, the fixed carbon increased by 6.81%, the calorific value increased by 6.90%, the equilibrium water content decreases from 7.06% to 4.46%, and the hydrophobicity increases. This research, based on the improvement of the quality of agricultural and forestry waste and the promotion of the strategy of converting waste into energy, has contributed to the advancement of sustainable energy production.

To explore the effects of low‐temperature torrefaction on physicochemical properties and energy–mass co‐benefit of corn straws, the products obtained after torrefaction at different low temperatures were studied. Through proximate analysis, ultimate analysis, scanning electron microscopy, and higher calorific value, the effects of different low‐temperature torrefaction on physicochemical properties of corn straws and energy–mass co‐benefit were studied. The results showed as follows: After low‐temperature torrefaction pretreatment, with the decrease of volatile matter, the H/C ratio decreased by 21.59%, the O/C ratio decreased by 19.05%, and the higher calorific value increased by 14.78% from 19.42 to 22.29 MJ·kg⁻¹. Therefore, low‐temperature torrefaction pretreatment can promote the volatilization of light components in corn straws, significantly increase the fixed carbon content, and then improve the mass density and energy quality into high‐grade fuels. The improvement of mass density is convenient for storage and transportation, and the improvement of energy–mass is convenient for improving the calorific value of combustion.

To study the water absorption characteristics of corn, rice, and wheat straw after thermal pretreatment (120 ~ 200 °C). This work introduces an internal particle diffusion model for the moisture adsorption mechanism and measures the water contact angle to assess hydrophobicity, establishing a linear relationship between the water absorption kinetic parameters and temperature. The results show that when the temperature rises to 200 °C, the hygroscopicity reduction extent of corn straw, rice straw and wheat straw are 58.45%, 28.32% and 12.12%, respectively, significant increase in hydrophobicity. The three-stage internal particle diffusion equation can effectively describe the adsorption process of straw to moisture. At 70% humidity, the diffusion rate constant decreased and the boundary layer thickness increased. The ASABE equation can accurately predict the moisture content of corn straw; the water absorption process of rice and wheat straw conforms to the Peleg equation, which is significant for the subsequent large-scale high-quality utilization of straw.

This work conducts a single-factor experiment to study the effects of biomass types on the relax density, volume expansion, durability, hydrophobicity, and processing energy consumption. We analyze the differences in the quality of the pellets, and optimize the compaction conditions suitable for different biomass types including straw, hardwood, shell, and herbaceous plant. The results indicated that with a compressing force of 60~1500 N, compressing time of 10 s, powder size of less than 0.5 mm, and moisture content of 10%, the relax densities of corn straw, rice straw, selenium-rich rice straw, weigela japonica branches, and camphor leaves range from 360 to 820 kg/m³, with a processing energy consumption of 17,360 to 28,740 J/kg; meanwhile, the relax densities of argy wormwood, forage grass, green grass, and peanut shells range from 340 to 840 kg/m³, with a processing energy consumption of 33,510 to 73,700 J/kg. Therefore, the compaction pretreatment effectively regulates the density of biomass pellets and reduces the processing energy consumption. This study analyzed the differences in the quality of pellets caused by the inherent characteristics of biomass, providing strong support for the directional depolymerization and enhanced pretreatment technology for the scaled production of biomass alcohol fuels.

Solid oxide fuel cell power generation systems are devices that utilize solid electrolytes to transfer ions for electrochemical energy conversion. A wide range of gases can be used as fuel gas, including hydrogen, natural gas, and carbon monoxide. Considering the high cost of pure hydrogen, hydrogen production from natural gas reforming has become a hot research area. In this study, the 4F-LCA method was employed to construct an evaluation framework, with a particular emphasis on the cost analysis of solid oxide fuel cell power generation systems, and uses a bottom-up approach to build a system economic analysis model to visualize the major costs involved in the system. An economic benefit analysis and sensitivity analysis were carried out for the 2 kW natural gas solid oxide fuel cell as a case by taking the financial net present value (NPV), internal rate of return (IRR) and payback period into account. In this study, the investment cost and payback period of a 2 kW solid oxide fuel cell system are obtained, which can provide a reference for the project construction and operation of solid oxide fuel cell systems.

To progress towards the “dual carbon” goal and reduce the cost and increase the efficiency of solid oxide fuel cells, this study conducts a full life cycle analysis of solid oxide fuel cells, in which the environmental impact caused by the operating devices’ manufacturing, fuel gas catalyst reforming, single-cell manufacturing, cell stack manufacturing, and energy consumption and emissions are systematically analysed. In this study, we establish an assessment model for solid oxide fuel cells by using the cut-off criterion. The results show that 96.5% of the global warming potential in the use of solid oxide fuel cells comes from the stack operating subsystem. The stack manufacturing subsystem, operating device manufacturing subsystem, and waste stack processing subsystem all contribute greatly to acidification, accounting for 32.89%, 44%, and 35.82% of the total acidification, respectively. These three subsystems also contribute significantly to eutrophication, contributing 23.11%, 22.03%, and 42.15%, respectively. Compared with traditional thermal power generation systems, solid oxide fuel cell power generation systems have slightly higher overall environmental benefits, and the reductions in greenhouse gas emissions and acidification potential reach 6.22% and 18.52%, respectively. The research results have guiding significance and reference value for subsequent energy-saving and emission reduction design and improvement efforts for solid oxide fuel cells.

Currently, the development of nonmetallic oxygen reduction reaction (ORR) catalysts based on heteroatomic-doped carbon materials is receiving increaseing attention in the field of fuel cells. Here, we used enzymolytic lignin (EL), melamine, and thiourea as carbon, nitrogen, and sulfur sources and NH₄Cl as an activator to prepare N- and S-codoped lignin-based polyporous carbon (ELC) by one-step pyrolysis. The prepared lignin-derived biocarbon material (ELC-1-900) possessed a high specific surface area (844 m² g⁻¹), abundant mesoporous structure, and a large pore volume (0.587 cm³ g⁻¹). The XPS results showed that ELC-1-900 was successfully doped with N and S. ELC-1-900 exhibited extremely high activity and stability in alkaline media for the ORR, with a half-wave potential (E_1/2 = 0.88 V) and starting potential (E_onset = 0.98 V) superior to those of Pt/C catalysts and most non-noble-metal catalysts reported in recent studies. In addition, ELC-1-900 showed better ORR stability and methanol tolerance in alkaline media than commercial Pt/C catalysts.

It is important to clarify the distribution of pyrolysis products from lignocellulosic biomass for its thermal transformation to produce high-quality bio-oil. Influences of the reaction temperature and catalysts on the pyrolysis product distribution from aspen wood (AW) and rice husk (RH) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The difference in components from the lignocellulosic biomass results in different pyrolysis characteristics of the biomass raw materials. The reaction temperature significantly influences the product distribution from AW and RH pyrolysis. In all AW catalysis experiments, acids (8.35%), ketones (3.79%), phenols (4.73%), and esters (1.50%) have the lowest content while carbohydrates (48.75%) demonstrate the highest content when taking zinc chloride (ZnCl₂) as the catalyst; the HZSM-5 molecular sieve (HZSM-5) promotes the generation of esters (7.97%) and N-compounds (22.43%) while inhibiting production of aldehydes (2.41%); addition of an MCM-41 molecular sieve (MCM-41) is conducive to increasing the contents of aldehydes (21.29%), furans (5.88%), ketones (22.30%), acids (20.46%), and hydrocarbons (4.85%), while reducing the contents of alcohols (0) and carbohydrates (0). In all RH catalysis experiments, the addition of ZnCl₂ helps increase the content of carbohydrates (39.16%) and decrease the contents of ketones (3.89%), phenols (5.20%), alcohols (2.34%), esters (1.13%), and N-compounds (3.09%); when applying HZSM-5 as the catalyst, hydrocarbons (18.28%) and alcohols (6.66%) reach their highest content while acids (13.21%) have the lowest content; MCM-41 promotes the generation of aldehydes (25.33%) and furans (5.55%) while inhibiting that of carbohydrates (1.42%).