BioEnergy Research最新文献

This study investigates the performance and emission characteristics of a diesel engine using a blend of 20% animal fat-based biodiesel (AFB20) under various FIPs (fuel injection pressures) and FITs (fuel injection timing). The objective was to optimize these parameters to enhance engine efficiency and reduce emissions. The experimental setup included a vertical, single-cylinder, four-stroke diesel engine equipped with an eddy current dynamometer and an exhaust gas analyzer. Methods involved varying the FIP between 180 and 240 bar and the FIT from 19 to 27° before the top dead center (TDC). Key performance indicators such as BSFC, BTE, and EGT were measured. Emissions of CO, UBHC, NOx, and smoke were also recorded. Results showed that at 200 bar FIP, the engine exhibited the lowest BSFC of 0.26 g/kWh and the highest BTE of 32.57%. The optimal FIT was 23° bTDC, achieving a BTE of 33.8% and a significant reduction in NOx emissions by 15.07%. Higher FIPs improved atomization, leading to better combustion and lower emissions of UBHC and CO. However, NOx emissions were higher at increased FIPs due to higher combustion temperatures. The study concludes that a FIP of 200 bar and a FIT of 23° bTDC are optimal for achieving improved engine performance and reduced emissions.

Over the past two decades, modeling the hydrolysis stage has been recognized as critical for understanding its behavior and determining optimal operating conditions for anaerobic digestion (AD). Traditional approaches, such as first-order and Michaelis–Menten kinetic models, account for substrate concentration and enzymatic activity, respectively, but neglect mass-transfer effects. In this work, we propose a semi-empirical model that integrates enzymatic catalysis with molecular diffusion phenomena in the microbial boundary layer. We derive a hydrolysis rate expression by combining Michaelis–Menten kinetics with Fick’s law of diffusion and validate it against experimental data from a thermophilic batch reactor treating cattle manure (55 (^{circ })C, 62 (g,text {VS},text {L}^{-1})). Compared to the first-order model (R(^2) = 0.940), our model achieves a superior fit (R(^2) = 0.973), demonstrating that diffusion resistance can significantly influence hydrolysis kinetics. By formulating the kinetic model in terms of explicit biochemical and mass-transfer parameters ((r_{h,text {max}}), (K_M), (k_d), (alpha )), it becomes possible to identify optimal operational strategies for enhancing hydrolysis efficiency. The results indicate that coupling enzymatic catalysis with diffusion provides a more accurate theoretical description than the first-order model and enables improved prediction of biopolymer solubilization in AD.

Composite carboxymethyl cellulose (CMC)-based films containing olive leaf extract (OLE) and the polysaccharide fraction from olive leaves (PFOL) were produced by a solvent casting method. The effects of OLE and PFOL contents on physical and functional properties of CMC composite films were assessed using a two-factor, five-level central composite design. Overall, water barrier properties of CMC-based films were significantly improved upon OLE and PFOL incorporation as confirmed by the observed reduction in their water absorption and water vapor permeability (WVP). Likewise, increasing PFOL content from 0 to 60 wt% significantly enhanced the flexibility of CMC/PFOL composite films, most likely due the increased mobility of CMC chains due to the formation of new hydrogen bonds between the CMC chains and the phenolic compounds in PFOL. Furthermore, the incorporation of OLE and PFOL endowed the CMC composite films with higher antioxidant capacity and excellent light barrier properties. Using the desirability function approach, an OLE contents of 0.51 wt% and 59.85 wt% PFOL were identified as the optimum factor levels providing maximum %E (23.28%), higher antioxidant activity (1.1 µmol TE/mg extract), and minimum WVP (17.62 g mm m⁻² j⁻¹ kPa⁻¹), with an overall desirability of 0.984.

Graphical Abstract

Exploring microalgae diversity has been a longstanding endeavour for producing valuable metabolites with significant biotechnological applications. This study investigates the microalgal diversity present in three distinct agroecological zones of Kerala, each varying considerably in topography, rainfall patterns, and altitude. A total of 209 microalgae strains were identified from 19 selected sites, showcasing the richness of diversity across these regions. Furthermore, 30 microalgae strains belonging to chlorophyceae (16) and cyanophyceae (14) were isolated and screened for their lipid and pigment productivity potential. Among the Chlorophyceae, Coelastrella sp. exhibited the highest growth rate (0.096 µ/day), while Ankistrodesmus falcatus and Monoraphidium contortum demonstrated the highest lipid productivity (23.69–22.17 mg/L/day). Carotenoid productivity was notably higher in Chlorella spp. and Monoraphidium contortum (343–268 µg/L/day). Among the Cyanophyceae members, Arthrospira platensis showed the highest growth rate (0.110 µ/day), followed by Oscillatoria sp. (0.89–0.78 µ/day), both exhibiting significant phycocyanin productivity (11.7–2.9 mg/L/day). The phycoerythrin productivity was exceptionally high in Synechococcus sp. and Leptolyngbya sp. (3.4–1.7 mg/L/day). Additionally, Synechocystis sp. exhibited moderate carotenoid content (4.5–3.8 µg/mg), while heterocystous Nostoc sp. and Anabaena sp. showed promising protein content (30–35%). The study highlights the potential of these isolated strains as promising candidates for biofuel and pigment production and their integration into a microalgae-based biorefinery.

Cockroaches are omnivorous insects that consume a diverse diet, including lignocellulose. This study investigated Periplaneta americana, which was fed exclusively on sugarcane bagasse, to evaluate biomass degradation across gut chambers and provide helpful information to the bioenergy industry. We analyzed enzyme activity, the composition of monosaccharides from bagasse, and lignin content in gut sections, feces, and food bolus. The fiber's morphology was also evaluated. Bagasse breakdown occurs sequentially (foregut, midgut, hindgut) through mechanical grinding and glycosyl hydrolase activity. The foregut primarily reduces particle size (> 90%) through chewing and enzymatic action, aided by chitinous teeth. Sugarcane bagasse in the midgut resembled the foregut's morphology, while the hindgut and feces displayed microorganisms and small surface holes. The study also explored links between the distribution of monosaccharides and glycosyl hydrolase activity in gut chambers. Monosaccharide profiling revealed elevated levels of rhamnose (~ 1. 1.2 μg·mg⁻¹ CW) and galactose (~ 5 μg·mg⁻¹ CW) in the foregut/midgut, with xylose peaking in the foregut (~ 15 μg·mg⁻¹ CW). Fucose, mannose, arabinose, non-cellulosic, and cellulosic (~ 1, 4, 4.2, 6, 6.2, 7, and 48 μg· mg¹ CW, respectively) remained stable across gut regions. Lignin (20% of the cell wall) persisted undigested in bagasse and feces (~ 20% dry weight). Enzymatic profiling of digestive enzymes showed that the foregut and midgut exhibited higher soluble enzymatic activities against βGlc (~ 3), βXyl (~ 1. 8), αXyl (~ 0. 02), βGal (~ 1.6. 6), αGal (~ 1), βMan (~ 1.3. 3), αAra (~ 0. 0.8), βClb (~ 0. 8), βGlca (~ 0.3. 3), and αRha (~ 0. 006 μmol sugar min⁻¹ mg ptn⁻¹). The hindgut (the main microbial chamber) showed lower activity for most enzymes. Fecal analysis indicated digestion/absorption of ~ 50% cellulosic glucose, 25% non-cellulosic glucose, 21% arabinose, and 26% xylose. These findings suggest that P. americana is a promising hemicellulose/cellulose degradation model without lignin breakdown under mesophilic conditions.

The synthesis of biodiesel from inedible feedstocks using bio-composite heterogeneous catalysts has emerged as a sustainable strategy to address global warming, enhance energy security, and preserve biodiversity. This review highlights advancements in eco-friendly catalysts derived from waste biomass, including eggshells, banana peels, agricultural residues (such as cocoa pod husks and sugarcane bagasse), and industrial by-products. These catalysts, which include CaO-based composites (such as Zn-doped CaO and Zr/CaO), sulfonated carbon materials, silica-impregnated CaO, and metal oxide-supported systems (such as ZrO₂/bamboo leaf ash and Cu/TiO₂), are designed to improve catalytic efficiency, reusability, and sustainability. Characterization techniques such as FTIR, XRD, SEM, XPS, and TGA confirm their structural stability, active sites, and thermal resilience, all of which are critical for optimizing biodiesel yield. The use of waste-derived catalysts not only reduces reliance on edible feedstocks but also promotes circular economy principles by valorizing biowaste. This review discusses challenges related to scalability, long-term stability, and cost-effective synthesis, as well as opportunities to refine catalyst design through advanced functionalization and hybrid systems. By merging sustainable chemistry with industrial applications, bio-composite catalysts offer a pathway to decarbonize energy systems, support local economies in developing regions, and align with global sustainability goals. The review emphasizes the need for interdisciplinary innovation to unlock the full potential of waste-derived catalysts in achieving a low-carbon future.

Biochar production and household energy utilization have garnered considerable attention in developing nations worldwide for over a decade. Gasification-based cookstoves mitigate numerous issues related to conventional cooking methods while effectively producing biochar. The novelty of this work lies in utilizing the gasifier stove for biochar production while simultaneously offering a clean cooking solution that empowers the livelihood of the rural population. The present study is carried out to investigate the effects of primary airflow on the thermal performance and biochar yield of a natural draft gasification technology-based improved cookstove. The inlet area of primary air varies from 25 to 100% in increments of 25%, producing biochar samples BC 25, BC 50, BC 75, and BC 100. The produced biochar is further characterized by performing proximate and ultimate analysis, X-ray diffraction analysis, FTIR analysis, and BET surface area analysis. The developed cookstove exhibits thermal efficiency in the range of 26.96–28.52%, while the biochar yield varies between 15.2 and 20.4%. The emission of carbon monoxide calculated per unit useful energy delivered to the pot ranges from 2.48 to 3.89 g/MJ_D corresponding to various airflow rates of primary air. The calorific value and percentage carbon content in the produced biochar samples range between 7424 and 8329 kcal/kg and 84.42 and 86.82%, respectively. The surface area of the biochar sample is increased three times with the increment in the primary air inlet area from 25 to 100%.

The low temperatures in Northeastern China offer a promising and energy-efficient approach for lignocellulose pretreatment. The effects of freeze-thaw pretreatment on the microstructure of corn stover hydrolysis characteristics and fermentation acid production were investigated using corn stover as the raw material. The experimental results demonstrated that the reducing sugar release and soluble chemical oxygen demand (SCOD) values of corn stover following freeze-thaw pretreatment exhibited increases of 15.8% to 67.0% and 13.9% to 68.9%, respectively, compared to those of the control group. Freeze-thaw pretreatment modifies the microstructure of corn stover by breaking hydrogen bonds in the amorphous region between cellulose and hemicellulose, facilitating lignin removal. The acid yield of the treated corn stover under optimal pretreatment conditions is enhanced by up to 77.9% compared with the control group. The initial pH pronouncedly influenced the acid yield of anaerobic fermentation of corn stover, with the highest acid yield of 3.8 g/L observed at pH values between 7.5 and 8. This study provides theoretical guidance for the industrial development of a low-cost and low-energy consumption pretreatment method in lignocellulose wastes.

Coffee roasting by-products represent a significant, underutilized side-stream globally. This study investigates hydrothermal liquefaction (HTL) as a method to convert these materials into hydrochar, water-rich light oil, and heavy oil. Using HTL at 300 °C for 60 min, we evaluated the energy content and properties of the resulting hydrochars, finding energy values exceeding 33 MJ/kg—significantly higher than the 19–21 MJ/kg of the raw materials. Hydrothermal liquefaction of spent coffee grounds produced more hydrochar (18 g) and heavy oil (1.2 g) than silverskin (12–14 g hydrochar and 0.1–0.5 g heavy oil). In contrast, silverskin generated twice as much light oil (9.7 g) as spent coffee grounds (4.6 g). Silverskin hydrochars exhibited higher gross calorific value (Baqué 33.95 ± 0.06 MJ/kg, Mariposa 33.86 ± 0.07 MJ/kg, Meira 33.22 ± 0.00 MJ/kg), lower ash content (3–5%), and reduced volatile matter (57–61%) than their raw form. Spent coffee grounds produced hydrochar with the highest gross calorific value (34.27 ± 0.01 MJ/kg), lowest ash content (0.8%) and the most significant reduction in volatile matter. Light and heavy oils produced were rich in alkaloids, fatty acids, and phenolic compounds, with potential applications in cosmetics and pharmaceuticals. This work contributes to both bioenergy production and circular economy strategies, valorising the two main side-streams of the coffee industry. With broad implications for sustainable waste management, this study highlights the potential of HTL to advance global bioenergy goals.