Bioenergy Production Research Articles

Microbial approach towards anode biofilm engineering enhances extracellular electron transfer for bioenergy production

Applying microbial electrolysis cells (MEC) is a biological approach to enhance the growth of high amounts of electroactive biofilm for extracellular electron transfer. The electroactive biofilm degrades the organics by oxidizing them at the anode and producing electrical energy. Addition of waste-activated sludge (WAS) with fat grease oil (FOG) produces an optimal reactor environment for microbial growth to enhance the exchange of electrons between cells via microbial electrolysis. The present work aimed to investigate the microbial approach to increase the extracellular electron transfer (EET) in microbial electrolysis cells. Results revealed that metabolites in electroactive microbes (EAM) grow viable cells that initiate high EET at anode sites. At optimum WAS with FOG addition, volatile fatty acid and current generation yield production was 2.94 ± 0.19 g/L and 17.91 ± 7.23 mA, accompanied by COD removal efficiency of 89.5 ± 14.4%, respectively. This study introduces a novel approach to anode biofilm engineering that significantly enhances extracellular electron transfer, offering a fresh perspective on bioenergy production. Our approach, which demonstrates that anodic biofilm enhances intercellular electron transfer, increases NADH-NAD ratio, and increases metabolite yield-fluxes, has the potential to revolutionize bio-electricity production. Results indicated that the electrolysis highlights MEC performance in power generation of 788 mV with 200 mL of anode volume of active viable cells by utilizing WAS with 11% FOG. The achievements of this study provide critical parameters for the anode biofilm engineering, demonstrating how growth cell volume, intercellular electron transfer, and increases in NADH-NAD ratio are evidence of an increase in the EET, compelling evidence for the resilience treatment and efficient current production. These findings are significant in advancing our understanding of bioenergy production.

A new approach to biotransformation and value of kitchen waste oil driven by gut microorganisms in Hermetia illucens

Hermetia illucens larvae are known for their ability to recycle organic waste, but their capacity to recover waste oils and the role of gut microorganisms in this process are not fully understood. To gain further insights, the biological recovery of waste frying oil into valuable lipids and the influence of gut bacteria on this biotransformation were investigated. The larvae efficiently digested and absorbed waste frying oil, demonstrating their potential for converting various oils into insect fat. The presence of different fatty acids in their diet significantly altered gut bacterial communities, enriching certain genera such as Actinomyces, Enterococcus, and Providencia. Redundancy analysis revealed that the composition and structure of these bacterial communities were predictive of their function in the biotransformation of fatty acids and the lipid biosynthesis in the larvae. Specific bacteria, including Corynebacterium_1, Providencia, Actinomyces, Escherichia-Shigella, and others, were identified to play specialized roles in the digestion and absorption of fatty acids, contributing to lipid synthesis and storage. These findings highlight the potential of Hermetia illucens in the biological recovery of waste frying oil and underscore the crucial role of gut microbiota in this process, offering a sustainable approach to waste management and bioenergy production.

EVALUATION OF CLIMATE CHANGE IMPACTS ON SUGARCANE AND CITRUS CROPS IN BRAZIL

Agricultural production is directly related to the environmental conditions. Favorable conditions can lead to higher productivity and product quality. However, climate change may pose a threat to agricultural production across the globe, as a rise in temperature may cause a decrease in the extent of suitable areas for growing certain crops. Using spatial analysis and data from future climate change scenarios developed by the IPCC, this research aims to evaluate the impact of climate change on the sugarcane and citrus plantations in the state of Sao Paulo from agroclimatic zoning mapping. The results of this research demonstrate that both crops can suffer great reduction of areas suitable for cultivation if there are severe changes in the climate regime, and these results can be used by managers and researchers to mitigate these potential impacts, as well as to clarify how climate change affects life on the planet, with the possible reduction of food and bioenergy production.

Genetic Diversity and Association Analysis of Traits Related to Water-Use Efficiency and Nitrogen-Use Efficiency of Populus deltoides Based on SSR Markers

Populus deltoides is one of the primary tree species for bioenergy production in temperate regions. In arid/semi-arid northern China, the scarcity of water and nitrogen significantly limits the productivity of poplar plantations. The identification of relevant molecular markers can promote the breeding of resource-efficient varieties. In this study, 188 genotypes of P. deltoides from six provenances served as experimental material. Genetic differentiation analysis, analysis of molecular variance (AMOVA), principal coordinate analysis (PCoA), unweighted pair group method with arithmetic mean (UPGMA) clustering, and genetic structure analysis were performed using selected simple sequence repeat (SSR) markers. Based on these analyses, the association analysis of water-use efficiency (WUE) and nitrogen-use efficiency (NUE) were conducted using general linear model (GLM) and mixed linear model (MLM) approaches. The results showed that 15 pairs of SSR primers successfully amplified across all 188 individuals, with an average of 7.33 alleles (Na) observed per primer pair. The polymorphism information content (PIC) ranged from 0.060 to 0.897, with an average of 0.544, indicating high genetic diversity in the selected markers. The average inbreeding coefficient intra-population (Fis), inbreeding coefficient inter-population (Fit), and inter-population genetic fraction coefficient (Fst) values were 0.005, 0.135, and 0.132, respectively, indicating high heterozygosity, substantial inbreeding within populations, and moderate genetic differentiation, with an average gene flow (Nm) of 1.964, suggesting substantial gene flow between populations. Additionally, molecular variance was primarily within individuals (84.12%). Genetic structure analysis revealed four subgroups, with some degree of genetic admixture among the provenances. In the GLM model, 11 markers were significantly associated with five traits (p < 0.05), with an average contribution rate of 15.82%. Notably, SSR132 and SSR143 were significantly associated with multiple traits (p < 0.05). The MLM model identified two markers (SSR47 and SSR85) significantly associated with ground diameter (p < 0.05) and one marker (SSR80) significantly associated with NUE (p < 0.05). This study identifies loci associated with WUE and NUE, laying a foundation for future genetic improvement and marker-assisted breeding strategies in poplar.

Investigating the sustainable energy generation potential of an invasive weed: Lantana camara.

Lantana camara, one of the world's top ten most invasive species, was initially cultivated for ornamental use. However, it spread uncontrollably across the fallow areas and agricultural lands, threatening approximately 44% of Indian forests. Its invasion disrupts ecosystems by suppressing nearby plant growth through allelopathy and poses toxicity risks to grazing ruminants. It significantly increases forest fire risk by adding large amounts of combustible biomass, particularly dried L. camara. Despite efforts to control it using mechanical, chemical, and biocontrol methods, the results have been largely unsatisfactory, with associated costs estimated at $18,000 per square kilometre. Considering these challenges, recent research explored the potential of L. camara as a bioenergy resource. TheL. camarabriquettes exhibit a heating value of approximately 20MJ/kg with a low sulphur (0.5%), nitrogen (1%), and ash content (2%), making them suitable for decentralised energy production. Furthermore, bioethanol production fromL. camarahydrolysate has shown promising results, yielding 0.33g/g withPichia stipitisand0.47g/g with Saccharomyces cerevisiae, which is comparable to other lignocellulosic feedstocks. Additionally, the gasification of L. camara using a downdraft gasifier produced syngas with a lower heating value (LHV) of 6.4MJ/Nm3. These findings demonstrate that using L. camara for bioenergy production presents a dual solution, addressing the growing demand for renewable energy and managing invasive species. This review aims to critically evaluate the potential and challenges associated with the different energy production pathways for L. camara, highlighting its role in sustainable energy generation.

Comparison of the Effects of NaOH and Deep Eutectic Solvent Catalyzed Tobacco Stock Lignin Isolation: Chemical Structure and Thermal Characteristics

Uncovering the structure of lignin from biorefinery has an important effect on lignin catalytic depolymerization and the production of bioenergy. In this study, two biorefinery lignins were isolated from tobacco stalks via alkaline and deep eutectic solvent (DES) catalyzed delignification processes, and the lignin heterogeneity structural characteristics were elucidated by gel permeation chromatography, 2D-HSQC, FT-IR, etc., to understand the relationship between the structure and the thermal characteristics of lignin. It was found that the lignins presented various structural characteristics and components, in which the predominant interunit linkages of black liquor lignin are β-O-4 and β-β linkages, and the β-O-4 linkages disappeared by DES treatment. DES lignins exhibited lower molecular weights and yields than black liquor lignin. Thermogravimetric analysis and fixed-bed pyrolysis were also performed to investigate the lignin thermal behavior. The results show that the DES approach can improve the bio-oil production from lignin and highlight the potential of DES lignin as a promising feedstock in the lignin pyrolysis process. This work provides a valuable example of the conversion of biorefinery lignin into pyrolysis products.

Intraspecific variability in plant and soil chemical properties in a common garden plantation of the energy crop Populus.

Optimizing crops for synergistic soil carbon (C) sequestration can enhance CO2 removal in food and bioenergy production systems. Yet, in bioenergy systems, we lack an understanding of how intraspecies variation in plant traits correlates with variation in soil biogeochemistry. This knowledge gap is exacerbated by both the heterogeneity and difficulty of measuring belowground traits. Here, we provide initial observations of C and nutrients in soil and root and stem tissues from a common garden field site of diverse, natural variant, Populus trichocarpa genotypes-established for aboveground biomass-to-biofuels research. Our goal was to explore the value of such field sites for evaluating genotype-specific effects on soil C, which ultimately informs the potential for optimizing bioenergy systems for both aboveground productivity and belowground C storage. To do this, we investigated variation in chemical traits at the scale of individual trees and genotypes and we explored correlations among stem, root, and soil samples. We observed substantial variation in soil chemical properties at the scale of individual trees and specific genotypes. While correlations among elements were observed both within and among sample types (soil, stem, root), above-belowground correlations were generally poor. We did not observe genotype-specific patterns in soil C in the top 10 cm, but we did observe genotype associations with soil acid-base chemistry (soil pH and base cations) and bulk density. Finally, a specific phenotype of interest (high vs low lignin) was unrelated to soil biogeochemistry. Our pilot study supports the usefulness of decade-old, genetically-variable, Populus bioenergy field test plots for understanding plant genotype effects on soil properties. Finally, this study contributes to the advancement of sampling methods and baseline data for Populus systems in the Pacific Northwest, USA. Further species- and region-specific efforts will enhance C predictability across scales in bioenergy systems and, ultimately, accelerate the identification of genotypes that optimize yield and carbon storage.

Sustainable bioenergy potential of peat-moss derived hydrothermal aqueous phase: Insights into methane production and organic transformation

Achieving Sustainable Development Goal 7 (SDG-7) by exploring bioenergy production from peat-moss derived hydrothermal aqueous phase (HAPs) through anaerobic digestion (AD). This study investigated six combinations of hydrothermal conversion temperature (HCT) and residence time (HCRT). Methane yields varied significantly, with the highest (256 mL/g COD) achieved at 200 °C:4h, while the lowest (97 mL/g COD) was at 320 °C:4h due to formation of toxic and refractory organics. Microtox analysis showed acute toxicity > 98 % for all HAPs. Notably, higher HCT and HCRT led to more complex and diverse organic patterns, promoting the formation of humus-like substances, ester, alkane alcohols, and aromatics. GC–MS analysis revealed a 23 % increase in aldehyde and ketone compounds at 320 °C:4h. Continuous experiments confirmed 29 % COD removal efficiency at 320 °C:4h and identified 13 refractory organics, highlighting challenges in biodegradability. These findings provided valuable insights for optimizing AD processes, enhancing bioenergy production, and advancing sustainable energy solutions in alignment with SDG-7.

Jerusalem Artichoke: Nitrogen Fertilization Strategy and Energy Balance in the Production Technology of Aerial Biomass

Jerusalem artichoke (Helianthus tuberosus L.) is a plant with considerable potential for energy generation due to its rapid growth, high biomass yield, and resistance to environmental stresses. The aim of this study was to determine the influence of the nitrogen fertilization strategy on the yield and energy balance in the production technology of Jerusalem artichoke (JA) in a perennial cropping system. The article presents the results of a three-year experiment which was conducted in Poland to determine the effect of different N rates (0, 50, 75, and 100 kg ha−1) supplied with mineral fertilizers and liquid digestate on the energy balance in the production of JA aerial biomass. The experiment had a randomized block design with three replications. The demand for energy in JA cultivation reached 16.2–26.3 (year 1) and 2.9–14.6 GJ ha−1 (years 2 and 3). Energy inputs in the cultivation technology were reduced by 17–19% (year 1) and 35–47% (years 2 and 3) when mineral fertilizers were replaced with digestate. Jerusalem artichoke yields were lowest in the technology without fertilization (12.5 Mg ha−1 DM). Dry matter yield increased significantly (by 43–55%) after the application of 75 kg N ha−1, regardless of fertilizer type. The energy output of biomass peaked (230.1 GJ ha−1) in response to a mineral fertilizer rate of 75 kg N ha−1. In turn, the highest energy gain (218.5 GJ ha−1) was noted after the application of digestate at a rate equivalent to 75 kg N ha–1. The energy efficiency ratio was highest in the technology without fertilization (20.1) and after the application of digestate at a rate equivalent to 75 kg N ha−1 (19.7). Regardless of the factors that limit agricultural production, the energy balance of JA biomass production was most favorable when JA was fertilized with digestate at a rate equivalent to 75 kg N ha−1. The results of this study may pave the way for future research on novel agronomic strategies for sustainable bioenergy production, including nutrient recycling.

Biochar for wastewater treatment: Addressing contaminants and enhancing sustainability: Challenges and solutions

In recent years, biochar has gained interest for its potential use in treating and removing contaminants from domestic, municipal, and industrial wastewater. When applied in fixed filter columns (BFCs), biochar can effectively immobilize, filter, and recover contaminants with high treatment efficiency. On average, COD removal is 80 %, nutrient removal is 71 % for nitrogen-ammonium and 57 % for phosphorus-phosphate, and pathogen reduction averages 2.4 log10 units. These results vary depending on factors such as the biochar's surface area, the conditions under which it was pyrolyzed, and operational parameters like hydraulic loading and retention time. Biochar addresses limitations in traditional wastewater treatment by leveraging adsorption, ion exchange, and biological degradation mechanisms. The larger surface area and functionalized surface of engineered biochar make it particularly effective in treating diverse pollutants, including heavy metals, nutrients, and emerging contaminants, such as antibiotic-resistant bacteria. As the global population and industrial activities increase, there is a pressing need for sustainable wastewater treatment technologies. Biochar addresses this need and serves as a waste valorization tool, contributing to bioenergy production, soil improvement, and other applications. The present review focuses on improving biochar's performance and durability in real-world applications by addressing challenges like physical degradation. It also proposes strategies to enhance biochar's properties and reuse potential.

The Role of Deadwood in Forests between Climate Change Mitigation, Biodiversity Conservation, and Bioenergy Production: A Comparative Analysis Using a Bottom–Up Approach

Recent literature highlights the crucial role of deadwood in forests, emphasizing its contribution to biodiversity conservation, soil fertility, climate change mitigation, and bioenergy production. However, managing deadwood presents challenges as decision-makers must balance trade-offs and synergies between these ecological benefits. A participatory approach, incorporating user opinions, can support effective decision-making. This study surveyed 1207 university students from Iran, Italy, and Türkiye to explore their perceptions of deadwood’s role and the potential trade-offs among climate change mitigation, biodiversity conservation, and bioenergy production. Results indicate a high level of awareness among students regarding deadwood’s ecological functions, but preferences vary significantly across cultural and regional contexts. Results show that for students of all three countries, the most important function related to the deadwood in forests is the provision of microhabitats for wildlife, while in second place for Iranian students, there is bioenergy production, and for Turkish and Italian students, soil fertilization. In addition, results highlight that students prefer the management strategies based on leaving both standing dead trees and lying deadwood in the forest. This study reinforces existing literature on deadwood’s importance for biodiversity and underscores the need for informed policies that balance ecological values with practical management considerations.

New Eco-Cements Made with Marabou Weed Biomass Ash

Biomass ash is currently attracting the attention of science and industry as an inexhaustible eco-friendly alternative to pozzolans traditionally used in commercial cement manufacture (fly ash, silica fume, natural/calcined pozzolan). This paper explores a new line of research into Marabou weed ash (MA), an alternative to better-known conventional agro-industry waste materials (rice husk, bagasse cane, bamboo, forest waste, etc.) produced in Cuba from an invasive plant harvested as biomass for bioenergy production. The study entailed full characterization of MA using a variety of instrumental techniques, analysis of pozzolanic reactivity in the pozzolan/lime system, and, finally its influence on the physical and mechanical properties of binary pastes and mortars containing 10% and 20% MA replacement content. The results indicate that MA has a very low acid oxide content and a high loss on ignition (30%) and K2O content (6.9%), which produces medium–low pozzolanic activity. Despite an observed increase in the blended mortars’ total and capillary water absorption capacity and electrical resistivity and a loss in mechanical strength approximately equivalent to the replacement percentage, the 10% and 20% MA blended cements meet the regulatory chemical, physical, and mechanical requirements specified. Marabou weed ash is therefore a viable future supplementary cementitious material.

Economic viability assessment of bioenergy production from agroindustrial wastes through fast pyrolysis

Spanish mainland crops, including olives, almonds, and pistachios, play a pivotal role in capital circulation and employment generation. This comprehensive study explores the economic feasibility on the utilization of diverse agro-industrial wastes from Spanish harvests as a promising feedstock for bioenergy production through fast pyrolysis. The fast pyrolysis process is simulated using Aspen Plus® software, employing techno-economic parameters such as Net Present Value (NPV), Internal Rate of Return (IRR), Payback Period (PBP), break-even, and minimum product sales price to analyze economic viability of the project. Two different scenarios, based on experimental data from previous studies, are compared. The profitability of this proposal is closely linked to the harvest, which serves as a limiting factor. In all scenarios, the project requires two years to recover the initial investment, demonstrating significant profits once production begins. When considering the impact of scaling up, the NPV of Scenario 2 for PS reached €369.55 M€. Sensitivity analysis reveals that the profitability of pyrolysis depends on the bio-oil selling price and the total production volume. Overall, this study confirms the economic viability of producing bioenergy through fast pyrolysis using various biomass residues. It highlights the potential of harnessing bioenergy from Spanish agro-industrial waste, paving the way for sustainable and economically viable solutions, as indicated by the NPV and IRR metrics.

Constraints on the availability of marginal land for bioenergy production in southern Sweden

Production of biomass for bioenergy on marginal land has been promoted to decrease the use of non-renewable energy without competing with food production. Previous estimates of marginal land and abandoned farmland in Sweden available for bioenergy production are based on general statistics and assumptions but lack in-depth analyses of potential alternative land-use values. Easily accessible public data only offer a coarse categorization of marginal land that may exaggerate the potential of using it for e.g. bioenergy production. This study assessed the regional availability and socioeconomic setting of marginal land in south Sweden. Our detailed analysis that combines easily accessible data with remote sensing shows that much of the land identified as marginal is already used for biomass production or has alternative use values, suggesting that using this land for additional bioenergy production may hamper other societal values, such as biodiversity conservation, food production, and recreation. In addition, the small size and lower productivity of the marginal land identified indicate challenges for cost-efficient biomass production. Thus, earlier assessments of bioenergy potential from marginal land have most likely overestimated the availability of suitable marginal land. We conclude that estimates of bioenergy production capacity on marginal land need to account for existing and potential alternative use values not included in easily available land use statistics, which limits the marginal land accessibility for renewable energy production.

In silico Analysis and Characterization of the F5H Gene Family in Sorghum bicolor and Its Role in Lignin Production

Ferulate 5-hydroxylase (F5H), a cytochrome P450-dependent monooxygenase, catalyzes the hydroxylation of coniferaldehyde, a crucial step in the formation of syringyl lignin monomer (S). However, evolutionary divergence, expression patterns under abiotic stress conditions (ABA, PEG and NaOH) and lignin content-related features of the F5H gene family in Sorghum bicolor have not been explored. This study envisaged mining of Sorghum genomic data leading to the identification of 61 SbF5H genes. Bioinformatics analysis revealed the phylogenetic evolutionary relations, gene structures, conserved motifs, physicochemical properties, and promoter cis-acting elements related to these genes and their encoded proteins. Based on the gene structural and phylogenetic features, these 61 SbF5Hs were grouped into 4 subclasses. The in silico expression analysis revealed higher accumulation of SbF5H1 transcripts in embryo and in root under stress conditions. Similarly, Other SbF5H genes have shown expression in stem and root, thus indicating SbF5H genes involvement in Sorghum lignin biosynthesis. By exploring into the functional aspects of the F5H gene, our study sought to shed light on its significance in influencing not only the chemical makeup of lignin but also the resultant plant phenotypes. This insight into the molecular mechanisms governing lignin biosynthesis can have implications for bioenergy production and crop improvement.

Hydrochar and Value-Added Chemical Production Through Hydrothermal Carbonisation of Woody Biomass

This study investigates the optimisation of hydrothermal carbonisation (HTC) parameters for transforming Whitewood biomass into hydrochar, focusing on bioenergy production and valuable chemical extraction as by-products. The optimal carbonisation was achieved at a process temperature of 240 -260 °C, which optimised the higher heating value of the hydrochar to 27-30 kJ/g and ensured a structural integrity similar to lignite coal. Increasing the temperature beyond 260 °C did not significantly enhance the energy content or quality of the hydrochar, establishing 260 °C as the practical upper limit for the HTC process. Residence times between 30 to 60 min were found to have minimal impact on the yield and quality of hydrochar, suggesting significant operational flexibility and the potential to double throughput without increasing energy consumption. The study also revealed that the process water by-product is rich in furan compounds, particularly furfural and hydroxymethyl furfural, with their highest concentration (125 mg/g of feedstock) occurring at 220 °C. The implementation of these findings could facilitate the development of a large-scale HTC facility, significantly reducing reliance on fossil fuels and enhancing economic viability by producing high-energy-density biofuels and high-value chemical by-products.

Carbohydrate Derived Value-added Products from Lignocelluloses

Abstract: Chemistry is confronted with the pressing issues of depleting non-renewable fossil resources and the imperative to combat environmental pollution, which is crucial for a sustainable future. Biomass stands out as the sole organic carbon source in nature among the array of sustainable resources available, positioning it as a prime substitute for fossil-derived chemicals and fuels. Extensive research has been conducted on the abundant lignocelluloses as a potential source for biofuels, bioenergy, and various valuable products, wherein, the incorporation of various processes in biomass fractionation to separate biopolymers (such as lignin, cellulose, and hemicellulose) has the potential to enhance the overall value of the process. However, industrial demonstration of biomass utilization for commercial products has been limited due to the challenges posed by the recalcitrance and complexity of biomass. Therefore, there is a need for efficient reaction processes to enable the production of bio-chemicals and fuels from renewable lignocellulose. This review focuses on the latest chemical methods developed for producing value-added chemicals from biomass-derived cellulose as a renewable feedstock.

Enhanced bioenergy production through dual-chamber microbial fuel cells: Utilizing citric acid factory wastewater and grape waste as substrates

IntroductionMicrobial fuel cell (MFC) is a variant of the bio-electro-chemical system that uses microorganisms as biocatalysts to generate bioenergy by oxidizing organic matter. Due to its two-prong feature of simultaneously treating wastewater and generating electricity, it has drawn extensive interest by scientific communities around the world. However, the pollution purifying capacity and power production of MFC at the laboratory scale have tended to remain steady, and there have been no reports of a performance breakthrough. Problem statementThis research was conducted to produce electricity and evaluate the efficiency of chemical oxygen demand (COD) removal from wastewater containing Citric Acid using a two-chamber microbial fuel cell without an intermediary. MethodologyIn this research, citric acid factory wastewater was used as the substrate, graphite as the electrode, Nafion membrane for proton transfer from anode to cathode, and grape waste as a carbon source. These Experiments were performed at room temperature and neutral pH. Also, the effect of three independent variables mixed liquor suspended solid (MLSS), Carbon: Nitrogen: Phosphorus stoichiometric ratio (COD:TKN:P), and grape waste on electricity production and wastewater treatment was investigated. Then, the optimal values of each variable were determined under favorable conditions for electricity generation and COD reduction. ResultsThe MFC was conducted at the optimal values of MLSS 1400 mg/L, the stoichiometric ratio of COD:TKN:P 140:10:1, and the grape waste dose of 1.4 g/L. At these conditions, the obtained maximum power density and current density were 18228.10 mW/m2 and 244.44 mA/m2, respectively. The maximum COD removal was 72% achieved in the values of MLSS 1400 mg/L, the stoichiometric ratio of COD:TKN:P equal to 260:10:1, and 1.4 g/L of grape waste. The maximum open circuit voltage was also recorded as 678 mV, obtained at MLSS 3000 mg/L, the stoichiometric ratio of COD:TKN:P equal to 200:10:1, and for a grape waste dose of 2 g/L. ConclusionThe results of this research showed that the use of grape waste to supply glucose to microorganisms in the MFC system has a significant effect on increasing energy production and COD removal, and it is recommended to conduct additional research in the future to improve the efficiency. However, scalability and practical application potential of these integrated technologies are the challenges towards their real-world applications in small scale trials.

Enhancing bioenergy and feed production in Southern Thailand: An approach through Leucaena cultivation and hydrothermal carbonization

This study addresses sustainability challenges in Southern Thailand, particularly the scarcity of biomass fuel and animal feed. It investigates the integration of Leucaena leucocephala cultivation with hydrothermal carbonization. The research compares the biomass yield and economic feasibility of growing Leucaena as a sole crop versus intercropping it with Para rubber trees. Sole cropping Leucaena produces higher biomass yields and is more economically viable. The wood stem of Leucaena is competitive with other biomass fuels used in local power plants, while its leaves, with over 14 % protein content, meet local animal feed market standards. Additionally, branches, which constitute 15.15 % to 30.58 % of the total biomass, are usually left as residue but can be used for hydrochar production. The study examines the effects of temperature (235 °C and 265 °C) and retention time (1, 2, and 3 hours) on hydrochar properties. Optimal condition (265 °C for 1 hour) produces hydrochar with high heating value and energy yield. Using these branches for hydrochar can significantly boost total revenue, with hydrochar contributing 54.9 % to overall revenue (4522.00 USD/ha). Integrating Leucaena cultivation with hydrothermal carbonization offers a sustainable solution, enhancing revenue, supporting local energy and feed needs, and promoting environmental sustainability.

Acid-assisted pretreatment for sweet elephant grass in choline chloride/glycerol DES: Experimental and mechanism study

Sweet elephant grass (SEG), a promising bioenergy grass, possesses considerable potential for bioenergy production. However, research on its pretreatment and utilization remains limited. In this study, small quantities of Brønsted acids were introduced to a deep eutectic solvent (DES) comprising choline chloride (ChCl) and glycerol (Gly) for SEG pretreatment. Under mild conditions (110 °C, 2 h), a maximum lignin removal rate of 90.08 % and a complete hemicellulose removal could be accomplished in the presence of Brønsted acid. Cellulose retention rates consistently above 70 % were obtained in all the cases, and a desirable glucose yield up to 94.07 % was achieved from the resulting cellulose after further enzymatic hydrolysis. The pretreatment mechanism was elucidated through a combination of characterizations and theoretical calculations, which demonstrated effective disruption of lignin and lignin-carbohydrate complex occurred by the CH···π, HO···H, and Cl···H bond interactions between lignin and DES. Furthermore, the scission of β-O-4 bond was promoted by Brønsted acids in DES. This systematic investigation paves the way for unraveling the mechanism of the efficient pretreatment of lignocellulose in acidic DES.