Search Results (369)

Transient extrusion defects are a fundamental process control challenge in fused granular fabrication (FGF), arising from the finite melt pressurization time of screw-driven extruders at each start–stop event. This study presents an integrated experimental and analytical framework for the characterization and open-loop feedforward compensation of these transient dynamics, demonstrated on two composite thermoplastic feedstocks: a recycled random polypropylene (RPP1) and a 20 wt% wood-fiber-reinforced polypropylene composite (WFPP). Unlike prior filament- or single-material feedforward strategies, this framework derives and statistically validates material-specific compensation parameters across two rheologically distinct feedstocks. Single-layer road experiments were conducted on a custom instrumented FGF platform across a 2³⁻¹ half-fraction factorial design varying melt temperature, print acceleration, and nozzle diameter, with screw speed stepped among 20, 40, and 80 RPM to excite transient states; deposited road geometry was digitized and spatially registered to the synchronized process signals. Main-effects regression confirmed that nozzle diameter is the dominant predictor of mean road width, while screw velocity exerts a significant negative effect attributable to speed-dependent backflow. Prediction-error minimization on the pooled multi-experiment dataset yielded a parsimonious first-order transfer function, G(s) = 0.990/(1 + 1.909s), whose time constant is physically attributed to melt compressibility in the barrel volume upstream of the nozzle restriction. This model was embedded in a G-code post-processor implementing two sequential corrections: a material-specific steady-state slip gain and a discrete linear-advance term parameterized by the identified time constant. For RPP1 at the nominal gain, the print latency interquartile range decreased from 5–20 mm to 2–8 mm without degrading steady-state dimensional accuracy; the combination of nominal gain with active retraction further reduced latency to near-zero. Analysis of covariance (ANCOVA) confirmed that optimal feedforward gains are statistically material-dependent across all three quality metrics (p < 0.05), providing statistical justification for material-specific compensator parameterization. The results establish a practical, hardware-agnostic route to reduce transient deposition defects in pellet-based additive manufacturing, extensible to additional feedstocks. Full article

Computational fluid dynamics provides detailed spatial distributions of physical fields in biomass boiler combustion, but the computational cost of each simulation limits its application in parametric studies and near-real-time workflows. This work investigates whether a Graph Neural Operator (GNO) can serve as a fast surrogate model that maps boiler operating parameters to six coupled CFD field distributions simultaneously. The reference case is a 10 kW wood-pellet boiler with internal flue gas recirculation (FGR), described and experimentally validated in an earlier publication by the authors. CFD data were collected on the symmetry plane of the combustion chamber for 80 operating points defined by the thermal load ratio (P/P₀) and the excess air ratio λ. A GNO surrogate was trained on 64 cases to predict temperature, velocity magnitude, static pressure, and mole fractions of CO, O₂, and CO₂ at each node of an unstructured spatial graph. On a held-out validation set of 16 operating cases, the model achieved R² values of 0.988 for temperature, 0.919 for velocity magnitude, 0.982 for pressure, 0.999 for CO, 0.992 for O₂, and 0.985 for CO₂. After training, each prediction is generated in a single forward pass, providing a computationally efficient approximation compared to the full CFD solver. A dedicated generalisation study on independent off-grid CFD cases confirmed that the surrogate interpolates within the parameter domain with essentially no loss of accuracy and degrades only moderately when extrapolated towards a higher thermal load and leaner mixtures. The results demonstrate that a baseline GNO surrogate can capture the spatial structure of coupled thermo-fluid and species fields in a realistic combustion geometry within the investigated parameter range and suggest applicability to digital-twin-oriented workflows where repeated parametric queries of boiler operation are required. Full article

Residential heater replacement programs in Chile have been evaluated primarily through fine particulate matter (PM) reduction metrics, without considering chemical speciation of the organic aerosols. This screening-level study characterized and compared particle-bound polycyclic aromatic hydrocarbon (PAH) and nitro-PAH emission factors from a residential firewood and a wood pellet heater, under controlled combustion conditions, and assessed their potential toxic equivalency (BaP-TEQ). Compound quantification used 1-nitropyrene as an index calibration compound; all results are semi-quantitative estimates with a combined analytical uncertainty of approximately 13–32%. Firewood combustion yielded a PAH-dominated emission profile with a total BaP-TEQ EF of 187.8 ng/kg, driven primarily by benzo[a]pyrene (BaP; individual contribution: 183.9 ng/kg). Wood pellet combustion showed a nitro-PAH-dominated profile under the applied semi-quantitative analytical conditions, with concentrations expressed as 1-nitropyrene-equivalent estimates and several compounds identified tentatively by NIST library matching, yielding a total screening-level BaP-TEQ EF of 972.1 ng/kg, approximately five-fold higher than firewood under the applied TEF framework and driven primarily by 6-nitrochrysene (toxic equivalency factor, TEF = 10). This screening-level estimate should not be interpreted as a direct human health risk between the two heating systems. Mean PM emission factors were 1.05 ± 0.55 g/kg for firewood combustion and 0.69 ± 0.15 g/kg for pellet combustion (approximately 1.5-fold difference). These results are reported descriptively given the screening-level nature of the analysis. The shift in particulate chemical profile from PAH-dominated in the firewood system to nitro-PAH-dominated in the pellet system suggests that wood pellets from pine may not be a sustainable approach to address air quality problems in Chile, since reductions in PM emissions alone may not capture relevant differences in the organic toxicological profile between these combustion systems. These findings provide a regional baseline for the chemical speciation of residential biomass emissions in Chile. Full article

Litter quality is a key factor influencing broiler welfare, particularly footpad health, yet the effects of loose versus pelleted natural litter formulations are not fully understood. This study assessed the impact of six treatments, composed of wheat straw, wood shavings, and peat in loose or pelleted forms, on litter moisture, pH, and footpad lesions during a 42-day fattening period. Litter condition was monitored weekly through scoring, moisture content, and pH measurements, while footpad integrity was assessed on a weekly basis throughout the fattening period. Loose litter exhibited higher moisture accumulation, greater pH variability, and earlier onset and more severe footpad lesions compared to all pelleted materials as well as wood shavings, which maintained more stable conditions and delayed lesion development. The initial physical properties and formulation of the litter materials contributed to these differences, with coarser textures potentially contributing increased mechanical stress on the footpads. Litter pH values converged and stabilized toward the end of the production cycle across all treatments. These results demonstrate that both litter composition and form significantly influence litter conditioning and broiler welfare. Careful selection and management of natural litter, with attention to moisture retention and pH stability, are essential to reduce footpad dermatitis and support optimal performance in intensive broiler production. Full article

Since 2024, most electricity production on Réunion Island has been achieved through combustion of biomass, using either imported wood pellets or locally produced bagasse. Their combustion generates two types of ash, depending on the biomass source: Wood Biomass Fly Ash (WBFA) and SugarCane Bagasse Ash (SCBA). Their chemical compositions differ significantly, leading to different potential applications. The composition of SCBA is similar to that of Coal Fly Ash (CFA), with low variability between batches. Therefore, SCBA could be used as an alternative to CFA, as a Supplementary Cementitious Material (SCM) or in composite cements. SCBA also meets most of the requirements of the NF EN 450-1 standard. However, grinding of SCBA appears necessary to achieve mechanical performance required by the standard. In contrast, WBFA exhibits variable chemical composition, mainly due to differences in pellet origin prior to combustion. Nevertheless, WBFA contains significant levels of chloride ions and sulfate, which may act as activators for materials such as GGBS or metakaolin (MK). Although the high unburned carbon content of WBFA increases water demand, their incorporation into GGBS-based binders (SSC or CEM III) or metakaolin-based systems shows promising potential, particularly for improving early strength. Full article

The world’s energy matrix faces challenges in replacing fossil fuels and reducing greenhouse gas emissions. Pellet production is effective for the correct disposal of agricultural waste through the production of biofuels. The objective of this work was to produce and characterize pellets from blends of pine and coffee straw residues, in addition to their compliance with ISO 17225-6/2021. The biomasses were subjected to analysis of dry and wet base moisture, bulk density, upper and lower calorific value (HCV and LCV dry), immediate, structural and elemental chemistry, chloride content, and thermogravimetric behavior. The pellets were produced in nine blends with the Amandus Kahl pellet mill, model 14-175, being submitted to analysis of productivity, moisture in dry and wet base, HCV and LCV dry, chloride, immediate chemistry, hardness, diameter and length, durability and percentage of fines, the analyses were compared by the Scott-knott test at the level of 95% probability. The blends that presented the best overall performance were 100% pine and a mixture of 87.5% pine and 12.5% coffee straws, especially for the higher calorific value (20.65 and 20.65 MJ/kg), moisture (8.98 and 9.17%), and ash (0.22 and 1%), but had limitations regarding mechanical durability (96.74 and 97.12%). The use of blends in pellet production is promising to promote the sustainable use of agricultural waste and the generation of clean energy. Full article

Italy is one of Europe’s largest consumers of wood pellets, while domestic production remains comparatively limited. In parallel, wood chips (WC) represent a strategic biofuel for power generation, where particle size distribution (PSD) affects handling and storage. Conventional PSD assessment relies on time-consuming methodology. This study proposes a patent-pending image-processing approach (Shadow Size Distribution—SSD analysis) for PSD classification of WC under bulk conditions. One hundred samples were characterized via both standard analysis and SSD. PSD data were aggregated into fine and coarse macro-fractions and used to define binary class labels. Multivariate analyses (PERMANOVA, PCA) and Support Vector Classifier (SVC) models were employed to evaluate the discriminative capability of SSD features. PCA revealed coherent relationships between PSD macro-variables and key shadow descriptors, particularly shadow number and area. The best SVC configuration achieved 0.77 test accuracy, with strong recall for coarse samples. Although overall performance was constrained by dataset size and imbalance, the results demonstrate that SSD features retain meaningful granulometric information, supporting further development toward automated, in-line PSD monitoring systems. From a sustainability perspective, the proposed SSD-based approach enables faster and potentially in-line monitoring of biomass quality, supporting more efficient combustion processes, reduced emissions, and improved resource management in bioenergy systems. Full article

Japan’s import market for wood pellets has expanded rapidly since the introduction of the feed-in tariff (FIT) scheme in 2012, with imports exceeding six million tonnes in 2024, positioning Japan as the world’s second-largest wood pellet importer. Despite this expansion, empirical evidence on its demand structure remains limited. This study employs a Dynamic Linear Approximate Almost Ideal Demand System (Dynamic LA-AIDS) model incorporating demand inertia stemming from long-term fuel supply contracts to analyze Japan’s wood pellet import demand from 2012Q1 to 2025Q3. The results reveal a distinct two-tiered structure: North American pellets behave as a strategic necessity, exhibiting price-inelastic demand and a tendency toward a stable long-run procurement pattern following price and expenditure shocks, suggesting procurement practices that prioritize supply security under long-term contracts. In contrast, Vietnamese pellets behave as a price-sensitive commodity, displaying price-elastic demand and relatively sustained responsiveness following such shocks. These results indicate a dual procurement strategy under the FIT scheme that balances stability and cost flexibility. Importantly, the Japanese demand structure differs from the more uniformly price-inelastic patterns observed in the EU and South Korean markets, providing new insights into how institutional frameworks shape biomass allocation and market responsiveness in renewable energy systems. Full article

The black carbon (BC) emission resulting from human activity comes mainly from fossil fuels and solid biomass burning, as well as transport fuels due to incomplete combustion. The biggest sources of BC pollution are currently diesel transport and domestic heating appliances burning solid fossil fuels or biomass. Firewood and pellet fuels were used for this BC research. The study used four domestic heating appliances using wood and agricultural waste pellets, as well as several types of firewood. The tests used a gravimetric particulate analysis method to determine the total amount of particulate matter. In further physical and chemical analyses, the emissions are broken down into components, i.e., substances of known composition that can be separated from the sample and weighed. In our study, the BC emissions varied from 0 to 120 mg/MJ depending on the type of boiler (automatic or manual), the combustion mode (based on oxygen supply), and the type of fuel. Emissions varied from 0–8 mg/MJ in a modern pellet-fired and automatically-controlled boiler, and from 1–25 mg/MJ in a wood-fired water heating boiler, with the highest emissions found for softwood (spruce). In the pellet stove with automatic feeding and control, BC emissions varied between 1 and 120 mg/MJ, with the highest emissions detected for wood pellets, and in the wood-burning fireplace, the emissions varied between 6 and 80 mg/MJ, with the highest emissions detected for birch firewood. Full article

This study assesses carbon footprint (CF) and explores mitigation potentials through improved resource efficiency for fire-resistant wood doors (WFDs) and fire-resistant bamboo doors (BFDs). Both WFDs and BFDs are certified to the Chinese national fire resistance standard GB 12955-2024, ensuring the same core fire resistance performance and functional equivalence. Results show that WFDs have a slightly lower CF (806.04 kg CO₂ e/m³) than BFDs (830.54 kg CO₂ e/m³), where the raw material phase acts as the main contributor (58.57–64.32%). Crucially, significant mitigation potentials are identified by enhancing resource efficiency across the product life cycle through reducing processing loss, and extending service lifespan, and sustainable recycling. Approximately 35.2 billion kg CO₂ will remain after reducing carbon loss by 5% in the Chinese wood/bamboo industrial sector. Recycling approaches (wood/bamboo panels, bio-based pellet fuel, and biochar) can be utilized with fewer emissions to economize bio-resources. The use of biochar provides greater carbon storage benefits and will help to limit the effects of climate change. Full article

This study experimentally investigated the movement, combustion, and potassium (K) and chlorine (Cl) migration behaviors of three biomass types: densified wood pellets (heavy), corn straw (lightweight), and wheat straw (lightweight, friable). The experiments were conducted under conditions representative of industrial coal-fired circulating fluidized bed (CFB) boilers, with a temperature range of 850–950 °C and a fluidization velocity of 6–8 m/s. Results show that densified wood pellets sink into the dense-phase zone and release volatiles slowly, in about 50 s. As the volatiles are nearly fully released, the pellets fracture multiple times along their length, eventually forming nearly spherical particles. Their movement and combustion processes closely resemble those of coal, making them suitable for direct co-firing in coal-fired CFB boilers. Conversely, corn straw and wheat straw exhibit low density, high volatile release rates (2 and 10 times that of wood pellets, respectively), rapid char fragmentation and abrasion, and high inherent K and Cl content (with >50% of K and >90% of Cl released). These properties lead to particle segregation, shortened gas-phase combustion time, an upward shift in heat release distribution, and potential risks such as high-temperature KCl corrosion, HCl dew point corrosion, ash slagging, and bed agglomeration. Therefore, untreated corn straw and wheat straw are unsuitable for co-firing in conventional coal-fired CFB boilers. This study provides essential data and engineering guidance: strict quality control is necessary for wood pellets to prevent Cl contamination, while pretreatment is mandatory for straw fuels. These findings offer practical insights for implementing diverse biomass co-firing strategies in coal-fired CFB boilers. Full article

This study develops and assesses sustainable polyvinyl chloride (PVC) composites reinforced with agro-industrial waste fillers, integrating an ontology-based lifecycle assessment (LCA) framework to enhance sustainability evaluation. Agro-waste reinforcements, including rice husk ash (RHA), coir, bamboo fibre, and wood flour, were examined for their capacity to improve the mechanical and environmental performance of PVC and to advance circular economy objectives. Empirical data from UK PVC window manufacturing were integrated with Granta EduPack, Eco Design, Eco Audit, OpenLCA, and Protégé within a multi-layered semantic pipeline that links materials, processes, and environmental indicators. The agro-filler composites exhibited lower embodied energy and CO₂ emissions than glass fibre systems, with the PVC + 30% wood flour formulation achieving the highest efficiency. The ontology framework, comprising 25 classes, 7 object properties, 26 individuals, 16 data properties, and 218 axioms (generated automatically by Protégé’s metrics feature and verified with the Pellet reasoner), ensured semantic interoperability and consistent validation across datasets, enabling transparent and traceable sustainability analysis. Overall, coupling industrial data with digital LCA and ontology reasoning provides a reproducible pathway toward net zero-aligned, sustainable PVC composite manufacturing. Full article

Wood and coal cofiring holds great potential for reducing greenhouse gas emissions from grate-fired combustion systems, as well as being widely technically feasible. This research was among the first to evaluate CO and NO_x levels within grate-fired cofiring at small utility scales. We evaluated two wood fuel types—high-quality aspen chips and lower-quality pellet mill residues. Each wood fuel was evaluated at two cofiring rates. Over 6 days of testing, CO contents ranged from 40 to 620 ppm, and NO_x contents ranged from 82 to 145 ppm. We found statistically significant differences in CO content when comparing low versus high cofiring rates, with high cofiring having greater CO concentrations. Relatively high CO emissions were attributed to greater moisture within the combustion chamber at higher levels of wood. Combustion efficiency versus cofiring rate was generally modeled the best as a quadratic relationship; carbon monoxide content versus cofiring rate was best modeled linearly. There were very few changes in combustion efficiency, fuel handing, or plant operation at the utility scale when cofiring at up to 15 percent of the energy value (versus no cofiring). From an operational standpoint, cofiring was relatively easy to implement and well received by plant managers. Full article

As solid biofuels gain increasing importance, the issue of rational management of the ash obtained from biofuel combustion is becoming increasingly relevant. This relevance will only increase in the future, since it is predicted that the main biofuel raw material will not be wood, but agricultural biomass with a high ash content. Biomass ash contains valuable nutrients, such as potassium and phosphorus, and therefore, it could be used for fertilization in agriculture. The concentration of nutrients in the ash can be made more balanced by granulating it with organic waste. This work presents the results of the environmental impact of using multi-crop biomass ash for fertilization of spring barley using the life cycle assessment method. Five scenarios were analyzed: (1) mineral fertilizer (MF), (2) non-granulated ash (NA), (3) ash and cattle manure pellets (ACM), (4) ash and sewage sludge pellets (ASS), and (5) ash and sapropel pellets (ASP). The results of the study show that all scenarios using ash for fertilization have a lower environmental impact compared with the scenario using only mineral fertilizers (MFs). The lowest carbon footprint (583.94 CO_2eq.) was determined for the ASP scenario. Normalization of the results showed that the ASS and ASP scenarios are the best from an environmental point of view, with the lowest environmental impact (24.90 and 24.60 Pt, respectively). Full article

Residential barbecuing is becoming increasingly popular worldwide, especially in cities, where it is not only a leisure activity but also an important social and cultural practice. Consequently, the number of grills and smokers in use continues to grow. This study evaluated the environmental performance of a household wood-pellet barbecue dual-function smoker/grill using a life cycle assessment (LCA) approach. The functional units selected were per cooking time (1 h) and per unit of energy delivered (1 kWh) at different cooking settings on the smoker. The results show that most of the impacts, including global warming potential (GWP) and resource use, originate from the production of the smoker itself, whereas emissions released during combustion, especially NO_x, are the main contributors to impacts such as acidification and smog formation. The GWP per hour of operation ranged from 0.44 to 0.63 kg CO₂ eq. From an operational perspective, cooking at intermediate temperatures (between 110 and 175 °C) generally leads to lower impacts per hour than very low-temperature smoking. When considering entire meals, meat typically accounts for most of the total impact, with the smoker’s contribution comparatively small. Overall, the study provides a useful reference and shows that both equipment design and food choices play a role in barbecue sustainability. Full article