BioEnergy Research最新文献

This study investigated self-heating and off-gassing of Scots pine (Pinus sylvestris) wood pellets made from sawdust generated from separated mature and juvenile wood. The pellets were produced at an industrial scale and stored in large piles of about 7.2 tonnes. The production process involved drying the sawdust using three different methods and to varying moisture contents. The results indicated significant influences of both raw material type (F ₍₆₎ = 61.97, p < 0.05) and drying method (F ₍₂₎ = 65.38, p < 0.05) on the self-heating of the pellets. The results from the multiple regression analysis further showed that both the raw material type and pellet moisture content significantly influenced the temperature increase, with strong correlations observed for pellets produced using low-temperature drying (F _{(3, 14)} = 83.52, multiple R² = 0.95, p < 0.05), and medium temperature drying (F _{(3, 13)} = 62.05, multiple R² = 0.93, p < 0.05). The pellets produced from fresh mature wood sawdust were found to be more prone to self-heating and off-gassing while steam drying the sawdust at high temperature and pressure led to a significant reduction in heat and gas generation across all materials. The heightened self-heating and off-gassing in mature wood pellet can be attributed to a higher proportion of sapwood in the raw material. The probable explanations to the observed differences are in line with biological mechanisms for self-heating and off-gassing, as well as the chemical oxidation of fatty and resin acids.

To enhance cellulose hydrolysis under high solid loadings, increasing the mixing intensity is often necessary, but this can lead to heightened product inhibition. In this work, the effect of mixing on high-solid cellulose hydrolysis was investigated. Through response surface optimization experiments, the optimal mixing intensities for 15%, 25%, and 35% (w/v) cellulose hydrolysis were obtained under different levels of product inhibition. A combined mixing optimization strategy was developed for different solid concentrations, aiming to enhance both the glucose yield and the conversion rate of microcrystalline cellulose and corn cobs. After optimization, the hydrolysis of microcrystalline cellulose resulted in glucose concentrations of 85 g/L, 130 g/L, and 167 g/L, corresponding to maximal conversion enhancements of 23%, 13%, and 8.6%, respectively. Similarly, the hydrolysis of corn cobs achieved glucose concentrations of 81 g/L, 124.6 g/L, and 140 g/L, with maximal conversion improvements of 4%, 5%, and 13%. These results indicate that the optimized strategy can effectively improve the conversion rate of high-solid enzymatic hydrolysis of cellulose.

There are no reports of production and characterization of polysaccharides in the genera Chlorella and Spirulina cultivated in seawater (SW) and brackish groundwater (BGW). Furthermore, there are few studies on the cultivation of these microalgae in seawater for this purpose. Therefore, the aim of the study was to evaluate the production and composition of polysaccharides in Spirulina sp. LEB 18 and Chlorella fusca LEB 111 grown in seawater and brackish groundwater, with and without nutrient supplementation. In this study, 100% SW and 100% BGW were used as nutrient sources and supplemented with different concentrations of nitrogen, phosphorus, iron, and EDTA sources that make up the Zarrouk/BG-11 culture media. Cultivating Chlorella fusca LEB 111 in SW, without the addition of nutrients, resulted in an approximately 23% increase in starch production (g/g). The cultivation of Spirulina sp. LEB 18 in SW and BGW, without the addition of nutrients, showed an increase in glycogen concentrations (50.5 and 40.75 g/100 g_biomass, respectively) and highest levels of exopolysaccharides (0.34 and 0.50 g/100 g_biomass, respectively) compared to the control. Moreover, exopolysaccharides compositional analysis has shown an increase in glucose content with salinity, and a decrease in xylose and glucuronic acid. This cultivation strategy demonstrates the viability of utilizing SW and BGW as alternatives to freshwater culture medium for microalgae that have high nutritional requirements, with the potential to produce exopolysaccharides.

Graphical Abstract

Poplar (Populus species and their hybrids) plantations can produce large amounts of biomass on agricultural land during the first rotation. However, there is limited knowledge regarding plantation re-establishment through re-sprouting (second rotation) after harvest, stand management options for such plantations, and biomass production during rotation length up to 20 years. In this study, we analysed biomass production responses to thinning treatments in an 18-year-old second rotation poplar plantation in Southern Sweden. The first rotation plantation was established with clone OP42 (Populus maximowiczii A. Henry × P. trichocarpa Torr. and Gray). The thinning experiment was conducted seven years after the first rotation harvest, comprising four treatments: unthinned – 6000 stems ha⁻¹, light thinning – 3000 stems ha⁻¹, medium thinning – 1100 stems ha⁻¹, and heavy thinning – 550 stems ha⁻¹. Eleven years after thinning, standing volume/biomass reached 484 m³ ha⁻¹ (162 Mg DM ha⁻¹) in the unthinned and medium thinning plots, 443 m³ ha⁻¹ (148 Mg DM ha⁻¹) in lightly and 338 m³ ha⁻¹ (113 Mg DM ha⁻¹) in heavily thinned plots. The mean annual increment was not different among the unthinned, light, and medium thinnings, 26 m³ ha⁻¹ yr⁻¹ (9 Mg DM ha⁻¹ yr⁻¹). The total production, including living, dead and removed trees, was highest following the medium thinning, 695 m³ ha⁻¹ (233 Mg DM ha⁻¹). Gradual self-thinning in the unthinned and lightly thinned plots was increased by a drought period. Overall, this study suggests that the second rotation of poplar plantations has high biomass production and provides an alternative to planting after harvest.

To combat the fast-degrading environment in this era, efforts are being made to consider biomass as feedstock for the production of biofuels and biofuel additives. Alkyl levulinates (AL), a good biofuel additive, exhibit excellent performance in improving the flow properties of biofuels. The growing market value of AL makes it highly desirable for large-scale productions. Unfortunately, the highly complex structure of biomass often hinders its conversion to AL, limiting its production. Thus, finding solutions to achieve highly efficient biomass conversion to AL is crucial. Catalyst dual-acidity is important in determining conversion effectiveness. The applications of AL, the roles of the catalyst acidic type in facilitating biomass carbohydrates conversions to AL, the types of catalysts employed and their impact, the prominence of the catalyst dual acidity, and the effect of reaction conditions on the conversion process are discussed. Dual-acidity Brønsted-Lewis catalyst enhances the AL yields and selectivity from carbohydrate conversion. Dual-acidity catalysts in the form of homogenous and heterogenous exhibited several advantages and disadvantages, which are compared in terms of catalytic performance and cost-effectiveness. Carbon-based catalysts are suggested as the prominent choice for large-scale AL production from carbohydrates. The outcome of this review will provide insights into the advancements in AL production from biomass carbohydrates.

The water deficit resulting from climate variations limits the profitability and sustainability of sugarcane fields, making water supply through irrigation necessary to sustain the potential production of sugarcane. However, the water used for irrigation purposes must be properly managed, ensuring the conservation of water resources and the reduction of costs with the use of inputs and energy. Pulsed drip irrigation aims to support irrigation management, improving the efficient use of water and mitigating the deleterious effects of water deficit. This study aims to evaluate the growth, productivity, and industrial yield of sugarcane cultivated under continuous and pulsed drip irrigation. A field experiment was conducted at the Experimental Sugarcane Station of Carpina, in Carpina in the State of Pernambuco, Northeast Brazil, from December 2020 to December 2021. The experimental arrangement was randomized blocks in a 2 x 5 factorial design, with two types of irrigation application (pulsed and continuous) and five irrigation levels (40, 60, 80, 100, and 120% of crop evapotranspiration – ETc), with four replications. Pulsed drip irrigation increased the yield of stalks (9%) and sugar (21%) in the sugarcane crop and ethanol (17%) derived from sugar in the juice. Pulsed drip irrigation, when compared to continuous irrigation, improved the performance of sugarcane, providing a reduction in water consumption and increasing growth, stalk yield, sugar and predicted ethanol yield. Thus, based on this study, pulse irrigation is an efficient approach to irrigation management, contributing to the stability of sugarcane production while conserving water relative to continuous irrigation.

Facing increasing social, environmental, and economic pressure to substitute non-renewable fossil resources with renewable ones, hemicellulose has received attention as a substrate for the production of high-value products such as packaging materials because of its non-toxicity, abundance, and biodegradability. Hemicelluloses in the cell wall are naturally substituted with acetyl groups, and the degree and pattern of acetylation vary among plant species, tissue and cell types, and plant maturity. Hemicellulose acetylation influences features such as the flexural properties of wood, polysaccharide interactions, plant growth, and stress resistance. However, hemicellulose is deacetylated during its separation from other biomass polymers, mainly via alkaline solubilization. Therefore, when industrial applications require a certain degree of acetylation, chemical acetylation is necessary, which occurs through an esterification reaction that links acetyl groups to hemicellulose, catalyzed or not. Acetylation may enhance some features of hemicellulose-based packaging materials, such as mechanical strength, processability, thermal stability, hydrophobicity, and oxygen and water vapor permeability. This review provides an update on the latest advances in plant polysaccharide acetylation, including the acetylation mechanism in the plant cell wall as well as the influence of such esterification on plant properties and wood industrial application. Recent developments and progress in hemicellulose chemical acetylation strategies have been summarized, disclosing the advantages and disadvantages of different solvents and catalysts applied and acetylation evaluation methods.

Co-pyrolysis behaviors of peanut shells (PS) and tea plant branches (TPB) were explored with a focus on the physicochemical properties, thermal degradation behavior, synergistic effect, and thermo-kinetic analyses. The differences between individual biomass and the equivalent blend were also highlighted. Results showed that the blend sample showed an enhancement in fixed carbon content but a reduction in moisture and ash contents, when compared to those of the individual PS. The average activation energies (E_a) of the equivalent blend estimated by three isoconversional methods (i.e., Friedman, KAS, and Starink methods) were 181.65, 166.87, and 167.14 kJ/mol, respectively. The average E_a and ΔH of the blend were quite lower than those of the TPB but slightly higher than those of the PS. During pyrolysis, ΔH and ΔG exhibited positive values which showed the decomposition was endothermic and non-spontaneous. Negative ΔS values were first observed, followed by positive ΔS values at late conversion stage.

Biochar is recognized for its potential in mitigating climate change, especially through carbon sequestration and soil improvement. To this end, it is important to use all co-products from pyrolysis in a sustainable and economically viable way. In this study, the conversion of sugarcane bagasse at varying pyrolysis temperatures was investigated using ¹H NMR spectroscopy and Chenomx for liquid fraction analysis. The yield of biochar decreased significantly from 45.3 to 3.5% with a temperature increase of 300 to 1000 °C. The morphological analysis revealed that biochar produced at lower temperatures (300 °C and 400 °C) showed tubular and spongy structures, whereas at higher temperatures (600 °C and 800 °C), the structures morphed into holes and thinned further, ultimately degrading further at 1000 °C. All samples of biochar showed characteristics promising for soil improvement and carbon sequestration (O/C < 0.4). The analysis of liquid fractions revealed that biomethanol reached its highest concentration of 19.28 mM at 800 °C, which coincided with the highest production of acetic and lactic acids. Additionally, the highest concentration of acetone was observed at 600 °C. These findings highlight the importance of optimizing pyrolysis conditions for enhanced yields of biochar and platform compounds, as well as the potential of the NMR and Chenomx in bioenergy research.

The unwashed alkali-treated lignocellulose can be directly enzymatically hydrolyzed and fermented via pH adjustment with acids. The use of acids would give a burden on production cost. Furfural residue (FR) which is the acidic solid waste from lignocellulose-derived furfural production process was employed in this study as a pH regulator. The corn cob-derived FR was used to adjust the pH value of alkali-treated corn stover (PCS) to 4.8 for enzymatic hydrolysis and ethanol fermentation. The unwashed PCS adjusted by FR got higher enzymatic hydrolysis efficiency (EHE) than the washed PCS samples. Meanwhile, the mixing of PCS and FR had a synergistic effect on the EHE of PCS. The fermentation of enzymatic hydrolysate from unwashed PCS-FR mixture at 20% solid concentration could attain ethanol production of 26.54 ± 0.02 mg/mL with a yield of 89.53 ± 0.08%. This work created a novel recycling way of FR as a pH regulator for improving the bioconversion of alkali-treated lignocellulose. It also provided a novel clue for the valuable valorization of wastes from corn production.