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Nanocrystalline cellulose (NCC) isolation from non-woody biomass is attractive to replace the current reliance on wood as feedstock. The predominant use of single acid hydrolysis cycle in existing literature may overlook the residual sediment. In this work, we explored the use of multiple acid hydrolysis to investigate the NCC isolation from unbleached kapok pulp. Initial screening using factorial design showed the significance of acid concentration, reaction time and temperature as crucial variables in determining the NCC characteristics, among five variables examined which also included sonication time and acid-to-pulp ratio. Subsequent optimisation using central composite design demonstrated that the optimal reaction condition for NCC recovered from supernatants entails a single cycle employing 63%w/w of sulphuric acid at 45 °C for 50 min with acid-to-pulp ratio of 30:1 mL/g and sonication time of 5 min. The NCC yield obtained (supernatant) was ∼19 % with PDI of 0.4, zeta potential of −39.7 mV and crystallinity index of 72.6 %. When combining with the further hydrolysis of sediments, the data showed comparable responses for NCC produced (yield, size and zeta potential) using either 3 cycles or 1 cycle. Nevertheless, opting for 3 cycles resulted in a lighter NCC colour owing to lower acid concentration and temperature. This study demonstrated that the feasibility of adjusting the number of hydrolysis cycles based on the desired outcome for NCC isolation. Multiple acid hydrolysis for NCC isolation from kapok seed pod fibres. [Display omitted] • First study on multiple acid hydrolysis for NCC production. • Single-cycle hydrolysis showed a higher yield of NCC with darker colour. • Three-cycle hydrolysis is beneficial for aesthetic quality of NCC. [ABSTRACT FROM AUTHOR]

Lignin is hardly degraded and presumably only scarcely structurally modified during the anaerobic digestion of straw and thus accumulating in the digestate remaining after digestion. As available industrial residue stream and due to the accumulation of unmodified lignin, such a digestate appears as promising substrate for the production of biogenic aromatics. One process for recovering monomeric aromatics from structurally unmodified lignin is the Reductive Catalytic Fractionation (RCF). Here, the RCF of straw digestates from a lab fermentation and from an industrial plant was investigated and compared to the RCF of unfermented straw as well as beech wood. It turned out that monomeric aromatics can be recovered from straw digestates by RCF. Removing impurities from the digestates by washing, increasing the hydrogen pressure and extending the reaction time to at least 7 h further increased the monomer yield. The selectivity towards γ-OH groups in the monomers can be controlled by the hydrogen pressure and the choice of hydrogenation catalyst. No yield-reducing influence of hydroxycinnamic acids found in straw got evident, however, only their purely ester-bound fraction could be easily removed and quantified. Compared to the straw digestates, monomer yields on biomass basis were lower from unfermented straw, but significantly higher from beech wood for all tested catalysts. Thus, although having a comparable lignin content, beech wood represents a higher yielding source for monomeric biogenic aromatics compared to straw digestates. • Lignin is accumulating in digestates during anaerobic digestion of straw. • Aromatics producible from straw digestate lignin by Reductive Catalytic Fractionation. • Order of aromatics yields per biomass: beech wood > straw digestate > straw. • Influence of ester-bound hydroxycinnamic acids tested by preceding ester hydrolysis. • Influence of impurities, reaction time and H 2 pressure investigated. [ABSTRACT FROM AUTHOR]

Biomass burning is responsible for emitting 90 % of total primary organic aerosols into the atmosphere. Products from pyrolysis are released to the atmosphere when gas-phase reactions are unable to oxidize them, and even narrow windows of release can produce a large fraction of the overall particle emissions. This work introduces an approach to predict particle emission during high-emitting periods of biomass burning. We trained a regression-based machine learning model to predict particle emission using data from pyrolysis experiments covering seven wood types under controlled conditions. The model considered experimental mass-loss rate (MLR) of the wood, wood density, and heating conditions as features for prediction of measured particle-phase real-time emissions. After training, the experimental mass-loss rate was replaced with modeled MLR from a two-dimensional finite volume model of pyrolysis to predict particle emission rate using only wood properties and the boundary conditions of pyrolysis. The hybrid model explains 80 % of the variance in particle emission and has comparable error metrics with the machine learning model that relies on experimental MLR. Errors are greatest during the initial transient where pyrolysis is occurring near the surface. • New approach to predict particle emission from specific periods of biomass burning. • Machine-learning model trained on 1-Hz data from pyrolysis of 7 wood types. • Gradient-boosting regression predicts emission from mass loss and other features. • Measured mass loss rate replaced with output of finite-volume modeling. • Eighty percent of variance in emission rate explained with hybrid model. [ABSTRACT FROM AUTHOR]

Wood, bark and leaves are indispensable components of forestry biomass, varied biological composition of which might not only form hydrochar of varied nature but also activated carbon (AC) of distinct pore characteristics. This was investigated herein by hydrothermal carbonization (HTC) of wood, bark and leaves of same poplar tree at 260 °C and subsequent activation with K 2 C 2 O 4 at 750 °C. The results indicated that organics in leaves were thermally unstable and fragmentation reactions dominated in HTC, producing hydrochar of much lower yield than that from HTC of cellulose/hemicellulose-rich wood and bark. Furthermore, the oxygen-rich hydrochar-leaves showed not only lower thermal stability than that of hydrochar-wood/bark, but also produced remarkably less AC in activation. The hydrolysis of sugary structures in especially wood and followed polymerization of the intermediates enhanced aromatic degree and resistivity of hydrochar towards cracking, increasing AC production but preventing development of porous structures. Hence, the AC-wood showed the lowest specific surface area (1315.2 m2/g). In converse, the highly unstable nature of hydrochar-leaves facilitated generation of mesopores (1038.9 m2/g) and also some macropores, achieving total specific surface area of 1843.8 m2/g. The abundance of cellulose/hemicellulose together with extractives and inorganics in bark formed AC-bark with highest specific surface area (2213.2 m2/g) and also most abundant micropores (1941.4 m2/g), rendering its superior capability for adsorption of tetracycline (680.3 mg/g). [Display omitted] • HTC of leaves of low sugary content forms less hydrochar and activated carbon (AC). • Hydrochar-leaves is O-rich and thermally unstable, forming AC of mainly mesopores. • Activating hydrochar-bark forms AC of most abundant micropores. • Abundant aliphatics in hydrochar determine pore type/abundance. • AC-bark of abundant micropores is superior for tetracycline adsorption. [ABSTRACT FROM AUTHOR]

While biochar is an effective and viable tool for alleviating climate change, monolithic biochar is emerging as a functional material for applications that enhance sustainability, such as renewable energy storage and low-cost, high-efficiency water purification. Its performance depends on its physical and chemical characteristics, including electrical conductivity. Monolithic biochar's bulk conductivity is expected to rely on the porosity and conductivity of its carbon matrix - intrinsic conductivity – a fundamental property that has not been systematically studied. The work discerns intrinsic conductivity and its dependence on biomass species and carbonization temperature. We carbonized four hardwoods, three softwoods, and bamboo following an ultra-slow pyrolysis procedure and characterized biochar's chemical and structural properties. We modified the two-probe method and measured bulk conductivity along the axial direction. The bulk conductivity and density followed the linear and the Reynolds-Hough relationships, allowing the determination of intrinsic conductivity. The intrinsic conductivity increased with pyrolysis temperatures and became independent of wood species at 1500 °C. According to the linear model, the highest value of wood biochar produced at 1500 °C was 14,600 S/m. Bamboo biochar had a higher intrinsic conductivity (21,000 S/m), attributed to bamboo's high cellulose content and large graphite nanocrystal size in its biochar. Moreover, the modified two-probe method minimized measurement uncertainty and enabled the quantification of natural variation in biochar conductivity, which was less than 10% for the same wood species. These findings will help strengthen monolithic biochar's potential as a low-cost, high-performance functional material. [Display omitted] • A linear relationship between bulk conductivity and density defines intrinsic conductivity. • Intrinsic conductivity increases with temperature and is independent of wood species. • The intrinsic conductivity of bamboo biochar is 21,000 S/m – higher than wood biochar. • The modified two-probe method allows the quantification of natural variation in conductivity. [ABSTRACT FROM AUTHOR]

Chemi-mechanical pulping (CMP) is a typical high-yield pulping technology to produce various papers and paperboards due to its high yield and high fiber properties. However, it is challenging to further improve its energy efficiency without the scarification of fiber quality. To attack this challenge, herein we study the effects of different hemicellulose pre-extraction on the viscoelasticity of wood cell wall, the energy efficiency, and product properties in chemi-mechanical pulping (CMP) process. Hardwood was first pretreated by NaOH to hydrolyze the benzyl ester bonds that link lignin with hemicellulose, aiming to partially remove hemicellulose and weaken the inter-fiber connections. Then, the hemicellulose-extracted wood underwent refining. The chemical distributions of wood, fiber morphologies, fiber surface fibrillation, energy consumption, and paper properties were extensively studied. The results showed that a 40.8% removal of hemicellulose corresponded to a 90.3% reduction in wood storage modulus (E') and a 68.3% decrease in specific refining energy consumption. Moreover, the weaker connections between microfibrils in the secondary layer, caused by hemicellulose extraction, promoted fiber surface fibrillation during pulp refining. The study elucidates the nonnegligible role of hemicellulose as the linking "bridge" between lignin and cellulose. It also provides a new mechanism in addition to the current classic pulping mechanism including lignin chemical/thermal softening and cellulose swelling in both CMP and chemi-thermomechanical pulp (CTMP). This study offers a feasible and efficient approach to extract hemicellulose from hardwood to reduce the refining energy without scarification of fiber quality, therefore, it holds promise for advanced and greener biorefineries. [Display omitted] • The mechanism of chemical-mechanical pulping about hemicellulose was supplemented. • Removal 40.8% of hemicellulose reduced wet woods' storage modulus by 90.3%. • LC ester bonds hydrolysis weakens connection inter-fibers and inter-microfibrils. • Wood de-hemicellulose optimized fiber separation and fibrillation in refining. [ABSTRACT FROM AUTHOR]

Biomass degradation by microorganisms may cause major losses during the storage of wood chips for energy production. Poplar wood chips from short rotation coppices are especially prone to degradation with dry matter losses (DML) of up to 25% within a storage period, emphasizing the need for countermeasures. Therefore, we investigated the potential of the addition of alkaline Ca(OH) 2 to the wet biomass of poplar wood chips and hypothesised that the establishment of an alkaline environment would reduce the activity of fungi, the primary wood degraders. Three industrial-scale piles (250 m³) with 0, 1.5 and 3% Ca(OH) 2 were installed in Güssing, Austria and for four months (April–August 2019) the pile temperature, pH, moisture content, gas evolution (O 2 , CO 2 , H 2 , H 2 S, CH 4) as well as DML were monitored. Ca(OH) 2 altered the physicochemical properties of the wood chips but did not prevent biomass losses. However, as compared to literature, the DML were, compared to earlier investigations, also low in the control. In addition, cultivation methods were performed to evaluate the diversity of thermophilic microbes throughout the storage. Numerous filamentous fungi belonging to the phyla Ascomycota and Mucoromycota were isolated, being Rhizomucor pusillus, Aspergillus fumigatus , Thermomyces lanuginosa and Thermoascus aurantiacus the dominant species. Only minor differences in the fungal composition were detected as a result of Ca(OH) 2 addition. Instead, clear shifts in colony forming units (CFUs) were detected as a function of progressing storage time, with a decrease of the number of propagules after four months. [Display omitted] • Wood chips from poplar were mixed with calcium hydroxide which led to a significant increase in the wood pH. • The application of additive led to low dry matter losses for poplar wood chips of ∼8% after 4 months. • Monitoring of physico-chemical pile characteristics during 4 months of outdoor storage. • Evaluation of the storage effect (pH and temperature) on cultivable thermophilic mycobiota. [ABSTRACT FROM AUTHOR]

Abstract In this study, pyrolysis of the wood samples with varied C/H ratio on distribution of the products was investigated. The results show that C/H ratio in the biomass drastically affects the yields of char, tar and gas. Poplar has a higher C/H content, and consequently it produces a higher yield of char and the lower yield of tar. Pine wood has the lower C/H ratio, and the pyrolysis produces the lower char but higher gas and tar yields. Furthermore, the C/H ratio in the feedstock affects the elemental composition and the stability of the tar. The higher C/H ratio in biomass resulted in the tar with a higher stability during pyrolysis of the tar. The C/H ratio also affected the formation of the aromatic ring structures in the tar. The pyrolysis of poplar with the highest C/H content produced more aromatics with smaller ring size in the tar, while that from pine with the lowest C/H content produced more aromatics with bigger ring size. The tars produced from the feedstock with the different C/H ratio show a large similarity in terms of distribution of the functionalities but with varied intensities. The TG-MS characterisation showed that the organics in the tar did not reach the equilibrium and could continue to decompose during heating, producing CO 2 via decarboxylation, CO via decarbonylation and H 2 via dehydrogenation reactions. The DRIFTS study of heating char in inert atmosphere showed that the char originated from the different biomasses had distinct stabilities and distinct tendencies towards aromatisation. Highlights • Pyrolysis of poplar with a higher C/H ratio produces more char and less tar. • Pyrolysis of pine with a lower C/H ratio produces less char while more gas and tar. • The C/H ratio also affected formation of the aromatic ring structures in tar. • TG-MS result showed that organics in tar did not reach the equilibrium. • DRIFTS study showed that different char had distinct tendencies towards aromatisation. [ABSTRACT FROM AUTHOR]

Abstract The demand for and supply of forest biomass have both been increasing in recent years, which will set new requirements for forest management. Thus, new studies on regionally suitable forest management regimes to fulfill the needs of potential new investments and the impacts on wood supply potential on regional socio-economic welfare are called for. The aim of this study was to examine the impacts of intensive forest management due to increased demand for wood biomass, from the regional economy point of view. In particular, the impact of intensive forest management on 1) regional gross domestic product (GDP), 2) private consumption, and 3) employment were assessed. The study was carried out by using computable general equilibrium (CGE) modelling combined with the requisite statistics and simulation of regional forest potential in the future. The results showed that total regional forest biomass supply with more intensive forest management could be increased annually on average by 26% (1.7 Mm3) by 2030 compared to the business as usual (BAU) scenario. In this study, regional demand was increased by a hypothetical saw mill (0.5 Mm3) and biorefinery (0.7 Mm3). Total regional socio-economic benefits could be 2.8% (€150 M) for GDP, 1.5% (€49 M) for private consumption and 1.6% (780 person-years) for employment, larger by 2030 than in the BAU scenario including multiplier effects. The study demonstrated how much regional socio-economic welfare would increase if regional wood demand with new investments combined with more intensive forest management and wood supply had more attention paid to it. Highlights • The study was carried out by using computable general equilibrium (CGE) modelling combined with the requisite statistics and simulation of regional forest potential in the future. • The results showed that total regional forest biomass supply with more intensive forest management could be increased annually on average by 26% (1.7 Mm3) by 2030 compared to the business as usual (BAU) scenario. • Total regional socio-economic benefits could be 2.8% (€150 M) for GDP, 1.5% (€49 M) for private consumption and 1.6% (780 person-years) for employment, larger by 2030 than in the BAU scenario including multiplier effects. • The results of the study indicated that the positive changes in the regional economy can be achieved with regional demand investments supported by more intensive forest biomass utilization. [ABSTRACT FROM AUTHOR]

Biochar may have beneficial effects on soil depending on its properties and pedoclimatic conditions. Highly sloping soils are prone to erosion and organic matter depletion, and biochar can be useful to restore soil fertility and quality, and crop yields. To test the effect of wood gasification biochar (WGB), we conducted a field experiment applying 0 and 60 Mg ha−1 of WGB only (no fertilizer) to a sub-alkaline and fine-textured soil under Mediterranean climate conditions. The effect of WGB on the soil physicochemical properties and on 12 enzyme activities involved in the C, N, P, and S cycles was monitored during a wheat-growing season along with its effect on grain yield. The results show that WGB was rather recalcitrant, and the application of a high dose of it had no effect on most of the soil physicochemical properties, enzyme activities and wheat grain yield. Since enzyme activities involved in the C cycle were similar in WGB-treated and not-treated soils, WGB failed to stimulate organic matter mineralization during the monitored period, with no contribution to N and P supply. Since WGB can contribute to soil C stock with no detrimental effects on wheat yield, wood gasification can allow recycling waste woody materials of urban origin to produce energy and return biochar back to agricultural soils. We suggest that future studies on WGB focus on the effect of its aging in soil on soil physicochemical and biochemical properties, and on crop performances. [Display omitted] • Biochar obtained by gasification of wood is recalcitrant. • Recalcitrant biochar negligibly affected physicochemical properties. • Recalcitrant biochar had no effect on 12 soil enzyme activities. • Recalcitrant biochar has no detrimental effects on wheat production. [ABSTRACT FROM AUTHOR]

Particle size plays a crucial role in biomass pyrolysis mechanisms and their subsequent industrial uses. However, an applicable kinetic method that combines thermogravimetric data with distributed activation energy model (DAEM) adapted to the sample size is still missing. This work investigated pyrolysis kinetics of two wood species (spruce and poplar) with five particle shapes (powder, particle, 5-mm diameter cylinders with heights of 1 mm, 2 mm, and 4 mm) and one additional reaction condition (powder with lid). The experimental data were numerically simulated by two Gaussian + one exponential DAEM distributions. Thermogravimetric results evidenced a significant effect of particle geometry on char yields, which increased by 81% and 66%, from powder to 4-mm high cylinders, for spruce and poplar respectively. The increase in particle size and use of a crucible lid led to an increase of exothermic heat. Elemental analysis demonstrated a contradictory relation between carbonization and mass loss, which was explained by secondary charring. Synthetic indexes built from the kinetics parameters of the DAEM model clearly depicts the effect of particle sizes. The prediction ability of the model was checked by further experiments performed at different time-temperature patterns with several particle sizes. Finally, correlations between dimensionless residual mass (DRM) and element compositions allowed us to determine the composition of secondary charring, which consists mainly of carbon. The elemental composition of char can therefore be predicted using the difference of DAEM kinetics between fine powder and a given particle size. [Display omitted] • Multiple sample geometries revealed effects of particle size on char formations. • A negative carbonization/mass loss correlation occurred while increasing particle size. • Synthetic indexes built from model parameters depicted kinetic differences. • Model's prediction ability regarding particle sizes was validated. • Strategy proposed to predict char compositions for a given size at any temperature-time pathway. [ABSTRACT FROM AUTHOR]

This paper explores social acceptance of different wood-based energy applications in the Great Lakes region in the Upper Midwest, USA. Specifically, the paper examines attitudes and perceptions towards residential wood burning, commercial-scale wood boilers for heat, combined heat and power (CHP) facilities, and industrial power generation in Michigan. In 2021, we conducted a state-wide survey (n = 207) and 30 semi-structured interviews with individuals representing different stakeholder perspectives, including regulatory agencies, biomass industry leaders, non-governmental organizations and scientists who have shaped biomass debates, forest products workers, and Michigan residents. Results suggest that the depth of an individual's knowledge about different types of wood energy applications generally led to more positive attitudes, particularly for smaller-scale uses of wood for heat. Despite perceived environmental, economic, and human health risks of using wood for different energy applications, across all stakeholder groups, 70% of respondents perceived environmental benefits, 61% perceived economic benefits, and 57% perceived health benefits. Changing economic and environmental conditions in different parts of the state contributed to people's attitudes toward different forms of wood energy and their perceptions of associated risks and benefits. A key recommendation of this study is that policy-makers and energy developers seek to understand the complex factors that influence social acceptance when planning for the adoption of new types of wood-based bioenergy technologies. • Perceptions of risks and benefits are critical to understanding social acceptance of wood-based bioenergy technologies. • Knowledge about wood-based energy technologies generally led to more favorable attitudes towards wood energy. • Residents who lived within 50 miles of a biomass facility did not necessarily have more knowledge about wood energy. [ABSTRACT FROM AUTHOR]

In France, residential wood heating represents 52% of the share of energy produced from renewable resources for heat production. The forest of the Grand Est region (FR) covers one third of the regional territory and 12% of the national forest area. The main purpose of this study is to assess and to compare the global warming and the human health effects of the wood energy sector at domestic and regional scales. Five scenarios systems were studied. S1 (wood-log scenario and S2 (pellet scenario) were compared in real conditions of use. S3 studies in details the pellet manufacturing process. The novelty of the study compares S1 and S2 at the regional scale with two new scenarios S4 and S5 considering the entire log inserts and pellets stoves listed in the region. A cradle-to-grave approach was applied including all stages from forestry operations to heat production by combustion. Scenario S2 leads to a higher global change than S1 with values of 73.7 and 44.1 kg CO 2 eq per ton of green wood, respectively. If the combustion stage of pellets emits less greenhouse gases than the combustion of logs, the stage production contributes for 67% of the total impact. The packaging was the main process having the highest health and environmental impacts. At regional scale, the combustion stage mainly enhances all impacts due to the presence of old appliances with low environmental efficiency. Public policies must continue their efforts to promote the replacement of old household appliances. • Combustion of wood logs produces 6 times more greenhouse gases than wood pellets at domestic scale. • The production of pellets has significant health and environmental impacts. • The packaging of pellets isresponsible for carcinogenic, non-carcinogenic, respiratory organic and climate change. • The use of old domestic appliances at a regional scale multiplies the effects of the combustion process on all impacts. [ABSTRACT FROM AUTHOR]

BIOS and RIKA developed within the ERA-NET-project “Small-scale BM based CHP” a new micro CHP technology based on a wood pellet stove (thermal capacity 10.5 kW) with a thermoelectric generator (TEG), that enables the operation of the stove without electric grid connection. Thereby, the wear- and maintenance-free and also noiseless TEG system is cooled by a water circuit which makes it possible to supply an additional room with heat. To achieve a self-sustaining operation of the pellet stove a TEG with an electric power of up to 50 W was installed into the casing of the pellet stove and the electricity consumption has been reduced significantly by an optimization of the control system and the selection of appropriate low voltage components. Based on transient system calculations and CFD simulations as well as test runs with two testing plants the system has been optimized. To demonstrate the practical suitability of the new technology in real life, 8 h load cycle tests were carried out. At these tests overall efficiencies up to 92.6% were achieved and in addition to the coverage of the own electricity consumption of the stove, 50 W h surplus electricity were produced which can be used to charge mobile phones or other small consumers. [ABSTRACT FROM AUTHOR]

Biomass resource assessment constitutes the foundation for integrated bioenergy planning in order to evaluate the sustainable feasibility and to estimate the additional bioenergy potential. Its spatial distribution is an essential criterion to facilitate the exploitation of the untapped bioenergy potential by guiding industry and decision-making processes. This paper provides regionalized and aggregated estimates of the potentially available resources for bioenergy in Switzerland (10 woody and non-woody biomass types). First, considering the different biomass characteristics and available data, appropriate methods at the finest scale possible were elaborated to estimate the annual domestic biomass amount which could theoretically be collected. Then, explicit and rationale restrictions for sustainable bio-energy production were defined according to the current state of the art. Finally, the additional potential was estimated considering the current bioenergy production. The procedures developed can be transferred to other countries and spatial scales according to the local situation and available data. The Swiss biomass theoretical primary energy potential was estimated at 209 PJ per year, with the major contributions from forest wood (108 PJ per year) and animal manure (49 PJ per year). Almost half of the theoretical potential can be used for bioenergy in a sustainable way (26 PJ from forest wood and 27 PJ from animal manure yearly). The main restrictions are competing material utilizations, environmental factors, supply costs, as well as scattered distribution and small scale feasibility. [ABSTRACT FROM AUTHOR]

Torrefaction is a promising biomass upgrading technology as it makes biomass more coal alike and offers benefits in logistics and handling operations. Gasification is an attractive thermochemical conversion technology due to its flexibility in the product gas end-uses. Therefore, it is valuable to investigate whether additional benefits are foreseen when torrefaction is coupled with gasification. Therefore, two commercial torrefied wood fuels and their parent materials are gasified at 800–850 °C under atmospheric steam-oxygen circulating fluidized bed gasification conditions and magnesite as bed material. The torrefied feedstocks consisted of wood residues torrefied by Topell at 250 °C (Topell black), and mixed wood and wood residues torrefied by Torrcoal at 300 °C (Torrcoal black). The gasification results show that torrefaction resulted in an increased gas quality, as it yielded higher H 2 and CO contents, a decrease of the CO 2 content, increased gas yield and a significant decrease of the total tar content for both feedstocks. For the Torrcoal samples, torrefaction resulted in a decrease in the carbon conversion efficiency (CCE). In addition, the cold gas efficiency (CGE) remained approximately the same due to the increase in the H 2 and CO contents. The Topell samples showed an increase in the CCE and CGE upon torrefaction, but this could be attributed to a significant grinding in the screw feeder. It is generally concluded that both torrefied fuels may offer benefits as a feedstock for steam-oxygen blown circulating fluidized bed gasification, in particular in terms of gas quality and yield. [ABSTRACT FROM AUTHOR]

Fuel blends may be used to meet several operational needs in thermal conversion of biomass waste, including optimization of ash properties and fuel conversion efficiency. In this study, online alkali measurements using surface ionization are employed to study synergistic effects produced by inorganic elements during co-pyrolysis/gasification of wood and straw waste. Synergistic effects on the fuel conversion behavior are not observed during co-pyrolysis, while alkali migration from straw to wood is clearly observed above 600 °C by online alkali monitoring. In contrast, synergistic effects on char conversion and alkali release are substantial during co-gasification. Positive effects on char reactivity during most of the gasification process are attributed to alkali migration from the straw to the wood char, and the most pronounced effect occurs at a gasification temperature of 900 °C and a straw content of 25%. Negative effects on char reactivity are observed at the final gasification stage, which is associated with a significantly reduced alkali release from fuel blends compared to pure wood char. The effect is attributed to the migration of silicon, phosphorus, and aluminum to the wood char, as revealed by scanning electron microscopy with energy dispersive spectroscopy, where the elements react with alkali to form catalytically inactive compounds. The mixing of biofuels is concluded to result in substantial effects on the fuel conversion efficiency, which should be taken into consideration in thermochemical conversion of biomass. [Display omitted] • Online alkali measurements during co-conversion of wood and straw waste. • Wood and straw waste have distinctly different alkali release features. • Alkali release during co-conversion cannot be predicted by simple mixing of the two pure biomass types. • Positive and negative synergies exist at different co-gasification stages. • Silicon migration is observed and causes low alkali release and negative synergy effects. [ABSTRACT FROM AUTHOR]

The size and shape of powdered wood particles are important properties when considering their use in wood burning or the production of biofuels, biocomposites and biochemicals. Different measurement techniques can be used to measure particle size, but unfortunately these do not provide information about the shape of the wood particles. In this study, a fast and reliable tube flow fractionation method (analysing time 3min; particle size range 1 μm-2000 μm; analysed particles per sample 30,000–200,000) is used to separate water-diluted wood powders which varies by size and shape. 30 different milled wood powder samples are analysed (average particle size from 20 μm to 300 μm and average aspect ratio from 3 to 10). The major benefit in tube flow fractionation method is that the concealment of the finest particles in CCD imaging is avoided by applying the imaging unit after the fractionation of wood particles. Wood powder can easily be separated into different fractions by leading the water-diluted sample flow into different beakers for certain time periods. The transmittance signal after tube flow fractionating yields information about the particle size, and optical imaging provides information about the morphology of the particles. It was found in this study that rotor impact milling to a finer size range produces small but elongated particles. Additionally there were only small differences in the particle size distributions between jet milled and oscillatory ball milled samples, but it was noticed that oscillatory ball milled powders have a significantly lower aspect ratio than jet milled samples. [ABSTRACT FROM AUTHOR]

The article presents the results of the experimental and theoretical studies of the ignition processes of dry particles of woody biomass with a wide variation in heating conditions. A detailed analysis of the typical frames of the videogram has shown that the temperature of the oxidizing agent affects the nature of the ignition process of a wood particle. Under conditions of moderate ambient temperatures (Tg ≤ 873K), ignition, as a rule, occurs in the gas region under the particle. At the same time, the ignition of wood particles under conditions of high-temperature heating (at Tg > 1073K) proceeds in the gas phase in a small (very thin) neighborhood around the wood particle along its entire perimeter. A model is formulated that describes the ignition under the considered rather typical conditions and differs from the known description of the processes of convection of gaseous pyrolysis products during the induction period. Based on the results of the experiments, the influence of the type of woody biomass on the characteristics and conditions of ignition of fuel particles has been analyzed. It has been established that dry particles of woody biomass made of pine under relatively low ambient temperatures (at T g ≤873 K) ignite much faster compared to particles of similar size from birch, aspen and cedar. Differences in ignition delay times reach 90%. At high ambient temperatures (T g ≥1273K), the ignition delay times of all four investigated fairly typical types of woody biomass differ insignificantly (the deviation of the ignition delay times does not exceed 5%). The analysis of the influence of the orientation of wood fibers in space relative to the direction of the heat flow vector on the characteristics and conditions of ignition has also been carried out. It is shown that the orientation of the wood particle in space does not significantly affect the characteristics and conditions of ignition. This trend has been registered for all four types of wood studied. • The ignition mechanism of a wood particle depends on the temperature of the oxidizer. • Pine particles ignite faster than birch, cedar and aspen particles at low temperatures. • The type of wood does not affect the ignition dynamics at high ambient temperatures. • The anisotropy of thermophysical properties does not affect the ignition dynamics. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of lignin has been widely regarded as a clean and reliable alternative to obtain value-added products from lignin, such as vanillin or guaiacol. This work aims to go one step beyond the production of low molecular weight molecules and explore the possibility of using lignin residues from electrochemical treatments in the context of biorefinery. To this end, a two-way valorization of lignin by electrochemical oxidation is proposed, in order to obtain a liquid phase enriched in low molecular weight organic oligomers and a solid phase of modified lignin to be used as bioadhesive precursor. Hydroxylation of lignin by electrochemical oxidation using boron-doped diamond (BDD) anodes was observed according to the FTIR and MALDI-TOF results, concluding that an applied current density of 10 mA cm−2 leads to promising modifications for the formulation of bioadhesives. Furthermore, NIPU bioadhesives with electrochemically modified lignin were successfully prepared and tested for use in particleboard panels, showing satisfactory mechanical properties, and thus paving the way for more environmentally friendly lignin modification procedures for the wood industry. • Organosolv lignin oxidation treatment with BDD electrodes. • Double way valorization into low molecular weight oligomers and hydroxylated lignin. • Electrochemically modified lignin to be used as bioadhesive precursor. [ABSTRACT FROM AUTHOR]

Agricultural biomass like wheat straw is known to be lacking natural binders to form durable pellets. Our previous research had shown that steam explosion of wood improved the durability of pellets. However, treated wood required drying prior to pelletization. Thermal conditioning is practiced in the animal feed industry to modify the ingredients of animal feed to produce high quality pellets. We hypothesized that thermal treatment of straw would result in biomass pellets with improved durability when compared to pellets made from untreated biomass. To test this hypothesis, the moisture content (mc) of the straw samples was adjusted to 5%, 10%, and 15% (wet basis). The moistened samples were subjected to dry heat in a sealed reactor set at 80, 100, and 120 °C for 5, 10, and 15 min. The treated straw samples were pelletized by using a single piston cylinder system. The highest durability 91.5% belonged to the treatment of 10% mc straw at 100 °C for 5 min. A response surface method confirmed that the initial mc 10%, treatment temperature 100 °C, and treatment time 5 min, produced the most durable pellets with the lowest unit energy input in forming pellets. • Thermal treatment by dry heat in a sealed reactor of remoistened wheat straw improved pellet durability. • Pellets made from 10% moisture, treated for 5 min at 100 °C had the highest durability of 91.5%. • Response surface method was applied to detect the optimal condition for producing durable pellets. [ABSTRACT FROM AUTHOR]

A one-dimensional model with consideration of internal and external heat transfer, particle shrinkage, moisture evaporation, and pyrolysis kinetics is developed to predict biomass torrefaction behaviors. Three different kinetic schemes (i.e. a lump kinetic scheme and two detailed kinetic schemes (Andrés Anca-Couce and IngwaldObernberger, 2016, and Debiagi et al., 2018) are evaluated to find the suitable pyrolysis kinetics for biomass torrefaction process. The modeling results are compared with single beechwood particle torrefaction experiments. The results show that the detailed kinetic scheme proposed by Debiagi et al. shows the best performance among the three kinetic schemes, and it can correctly predict particle shrinkage, particle conversion, mass loss history, and biochar C/H/O compositions, while the lump kinetic scheme underestimates torrefaction rates and particle shrinkage degree at low temperature conditions (280–370 °C), and the kinetic scheme proposed by Andrés and Ingwald underestimates carbon concentration and overestimates the oxygen concentration of torrefied wood at high temperature conditions (370, 400, and 430 °C). Therefore, the kinetic scheme of Debiagi et al. is considered to be the most promising kinetics in particle-scale modeling of the torrefaction process. A sensitivity analysis is also performed to evaluate the effects of modeling parameters on modeling results as well as study the control mechanism of torrefaction process. The results show that modeling results are significantly influenced by parameters involved with external and external heat transfer related, boundary conditions, and reaction rate, indicating torrefaction process of large particles is controlled by both internal and external heat transfer, and kinetics. • A one-dimensional model is developed to predict the biomass torrefaction process. • Heat transfer, particle shrinkage, evaporation, pyrolysis considered in the model. • One lumped and two detailed pyrolysis kinetics are assessed and analyzed. • The detailed kinetic scheme proposed by Debiagi et al. shows the best performance. • The torrefaction process is controlled by both heat transfer and kinetics. [ABSTRACT FROM AUTHOR]

Finding methods to classify heterogeneous logging wastes from sustainable forest management in the Brazilian Amazonia is essential to increase the production and quality of charcoal. This study proposes a method to classify logging wastes of 12 Amazon hardwoods based on near-infrared (NIR) spectroscopy. The traits evaluated were basic density (BAD) and wet basis moisture content (MCwb). The spectral signatures obtained from the radial and transverse surfaces of the wood samples were submitted to principal component analysis (PCA) and partial least squares–discriminant analysis (PLS-DA). Spectral data measured on the radial surface of the wood yielded clearer clusters in the PCA score graph, considering the five BAD classes (very low, low, medium, high, and very high). The most promising PLS-DA model for wood classification based on BAD classes was calibrated with the radial surface spectra treated by the first derivative and validated in an independent lot with 97.9% correct classifications. A few incorrect classifications of low-density wood occurred. Still, NIR spectroscopy combined with multivariate statistics proved to be a reliable and fast tool to distinguish the wood from branches of native Amazonian species concerning BAD. It will enable more rationality and sustainability in using these natural resources for bioenergy purposes. • The proposed segregating woody wastes based on density is outlined in this study. • The basic density, diameter, and volume of the waste logs influenced their moisture. • Woody wastes of different densities have different spectral signatures. • A new classification of the waste basic density based on PCA analysis was proposed. • NIR spectra are promising for classifying woody wastes in density classes. [ABSTRACT FROM AUTHOR]

Storage of woody biomass in large wood chip piles is unavoidable for biotechnological applications, but comes along with considerable biomass-, energy- and thus, economic losses due to exothermic reactions and microbial degradation. The homogeneous amendment of the storage piles with an alkaline stabilization agent, calcium hydroxide (Ca(OH) 2), was found to decrease dry matter loss in Picea abies; for Populus canadensis piles the effects cannot clearly be deduced. Here we investigated the bacterial and fungal communities of industrial-scale wood chip piles (250 m3) of these two different tree species and related them to physicochemical conditions and enzymatic activities after 35 and 120 d, representing short- and long-term storage of the wood chips, respectively. Coming from different wood types (hard vs. softwood), we expected the communities to converge over time, due to similar storage conditions. Despite pH posing selective pressure, we expected a minor Ca(OH) 2 effect as already known from previous studies. We found that the effectiveness of Ca(OH) 2 addition depended on the wood type that determined both the native microbial seeding community and temperature pattern of all piles, thereby exerting selective forces of differing strength. Generally, a thermophilic community consisting of single fungal and variable bacterial taxa were identified. As expected, the microbial communities from P. abies and P. canadensis converged over time. Biomass loss was connected to C-cycle related enzymatic activities and to the abundance and composition of fungal communities. Chaetomium sp. was identified as potential key taxon determining biomass degradation under the given storage conditions. [Display omitted] • Wood type determines native seeding microbiota for thermophilic storing conditions. • Microbiota from different wood types converge during storage in outdoor piles. • Single thermophilic fungi gain importance. • Ca(OH) 2 addition counteracts dry matter loss in Picea abies. [ABSTRACT FROM AUTHOR]

Populous deltoides wood is a suitable raw material for ethanol production, since it has high cellulose content. Efficient degradation and subsequent conversion of lignocellulosic biomass to bio-ethanol, requires physico-chemical pretreatments followed by enzymatic hydrolysis to obtain high overall yields of sugars. Microbial hydrolytic enzymes are actively utilized for biomass degradation and bio-ethanol production. Four glycosyl hydrolases (GHs) namely; three subunits of cellulase, endoglucanase ( ThWF5-endoglucanase ), exoglucanase ( ThWF5-exoglucanase ) and β-glucosidase ( ThWF5-glucosidase ), and xylanase ( ThWF5-xylanase ), from fungal strain Trichoderma harzianum WF5 - isolated from decayed wood, were pulled out and subsequently characterized. Analysis of full length sequences and prediction of secondary and tertiary structure showed that these enzymes shared homology with the respective enzymes of other Trichoderma species and have comparatively evolved structure to express catalytic activity under broad range of environmental conditions. Respective GHs were partially purified and used for the enzymatic hydrolysis of P. deltoids wood after pretreatments. The pretreatment of P. deltoides wood with sulfuric acid and hydrogen peroxide (H 2 SO 4 + H 2 O 2 ) at 121 °C for 60 min was determined as the best condition to high recovery of reducing sugars after enzymatic hydrolysis. The overall high ethanol yield of 15.6 g/l and fermentation efficiency of 61.1% was obtained when fermentation was performed on pretreated poplar wood slurry followed by detoxification with calcium hydroxide. High bio-ethanol production from P. deltoides wood and molecular characterization of glycosyl hydrolases used, provide insights that this wood offers a potential source for biofuel production while T. harzianum WF5 is a treasure house of robust degrading enzymes. [ABSTRACT FROM AUTHOR]

The objective of this research was to investigate the effects of the conditions of hot water extraction (HWE) on abundance, properties, and structure of lignin depolymerization products. HWE of extracted softwood (ponderosa pine) was conducted using temperatures from 140 to 320 °C for 90 min. HWE materials were then subjected to a soxhlet extraction process using dichloromethane (DCM). The composition and molecular weight of this DCM-soluble material was conducted using semi-quantitative Py-GC/MS and ESI/MS, which showed that this material is rich in lignin with low molecular weight (<1200 g mol −1 ) and low polydispersity (∼1.4). The highest yield of this material (∼4.2%) was obtained in material processed at 260 °C. Py-GC/MS of the solid fraction after the DCM process showed a progressive reduction of products of the pyrolysis of lignin as the HWE temperature increased. This finding suggests that the lignin content in the solid decreased due in part to migration from the cell walls and middle lamella to the particles surfaces, particularly the inner surface of the cells. SEM and AFM techniques helped to visualize the ability of this DCM-soluble extract to adhere to cellulosic fibers. Therefore, this lignin-rich material presents properties that depend on the conditions of the operation. Results indicate that during HWE it is possible to control the process parameters to limit or increase the amount of DCM-soluble lignin and its properties as required for downstream processes. [ABSTRACT FROM AUTHOR]

Softwood substrates are recalcitrant in enzymatic hydrolysis to reducing sugars, in part because of unproductive binding of enzymes on lignin. Interactions between polyethylene glycol (PEG) and a softwood substrate were characterised in order to estimate the PEG loadings required for effective blocking of unproductive enzyme binding. For the first time, the adsorption of Rhodamine labelled PEG ( M w 3400) on thermo-mechanically treated Pinus radiata fibres was characterised by fluorimetry, giving a best-fit binding constant of 68 L g −1 . This was considerably stronger than published binding constants of 6 L g −1 for enzymes on lignin, accounting for the success of PEG as an additive. Glucose yields from enzymatic hydrolysis of the same substrate, when unlabelled PEG ( M w 4000) was used, were consistent with a PEG adsorption capacity of 0.01–0.02 g g −1 substrate. Thus, PEG was shown to be effective at affordably low loadings and further mathematical modelling work predicts savings correspond to 6 kg PEG per tonne when pretreated Pinus radiata substrate was processed at higher substrate concentration. [ABSTRACT FROM AUTHOR]

Harvested wood products (HWPs) in-use, disposed to landfill, and the charcoal created by biomass fuel burning substantially store carbon and potentially mitigate the greenhouse gas effect. To quantify the HWPs carbon storage, we developed a carbon accounting framework, which has the ability to incorporate the influence of technological advancement on HWPs carbon storage. Through applying this framework together with the wood harvesting data of Maine, USA during the period of 1901–2019, we concluded that the current HWPs carbon pool size is 52 Tg C, which is 11% of the carbon stored in the entire forestry sector and wood products of Maine, USA. Technological advancement potentially increases the HWPs carbon storage by as much as 44% to 75 Tg C. In addition, the average net annual carbon sink can be increased from 0.44 Tg C to 0.63 Tg C. Production of innovative wood products with long service lives plays the most important role in expanding the HWPs carbon pool; however, the higher processing efficiency and recycling rate are less important. [Display omitted] • An advanced harvested wood products carbon accounting framework is developed. • The current carbon storage in harvested wood products is 52 Tg C in Maine, USA. • Innovative wood products effectively expand the carbon stored in harvested wood products. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass has been identified as a renewable and sustainable feedstock to produce liquid hydrolysates as a suitable substrate to produce a variety of compounds through biochemical processes. Nevertheless, the main challenge to using this substrate is the hydrolysis needed to release fermentable sugars. This pretreatment leads to the production of microbial toxic compounds such as furans, phenols and organic acids. In this work, an oleaginous yeast, R. toruloides NRRL 1588, was used to study its ability to degrade inhibitors in C5 and C6 wood hydrolysates obtained from forestry residues. The study showed that R. toruloides NRRL 1588 can grow, accumulate lipids, and degrade up to 8.01 mgL−1 h−1 of furfural, 5.63 mgL−1 h−1 of 5-hydroxy methyl furfural, 1.70 mgL−1 h−1 of levulinic acid, 1.15 mgL−1 h−1 of syringaldehyde, 0.67 mgL−1 h−1 of vanillin, and 1.03 mgL−1 h−1 of vanillic acid. This work confirms the robustness of R. toruloides NRRL 1588 when grows in wood hydrolysates containing inhibitory compounds. [Display omitted] • Degradation of furfural, 5-HMF, vanillin, syringaldehyde, vanillic and levulinic acid. • Tolerance of R. toruloide s to microbial inhibitory compounds present on wood hydrolysates. • R. toruloides accumulate lipids in presence of microbial inhibitory compounds. • Wood hydrolysates are a potential and renewable microbial culture media. [ABSTRACT FROM AUTHOR]

Abstract: The Authors surveyed 6 industrial chipping operations for a whole work year, collecting data about machine usage, product output, fuel consumption and chipper knife wear. Despite the challenging work conditions offered by mountain operations, industrial chipping contractors manage to achieve a high machine use, ranging from 500 to over 2,500 h year−1. Product output varies between 18,000 and over 120,000 m3 loose chips per year. In order to acquire enough jobs, operators may travel between 1,500 to over 20,000 km in a year. Industrial chipping contractors adopt different operational strategies to achieve their production targets, and they equip accordingly. Some operators prefer to tap smaller local areas and opt for smaller tractor-powered chippers, which are less powerful and productive than larger independent-engine units, but cheaper and capable of negotiating low-standard forest roads. Others prefer to explore larger areas and achieve higher product outputs, and they opt for larger independent-engine chippers, often mounted on trucks. Long term productivity varies with machine type: tractor-powered units produce between 40 and 50 m3 loose chips per hour, whereas larger independent-engine chippers produce between 60 and 90 m3 loose chips per hour. Specific fuel consumption is about 0.5 L diesel per m3 loose chips, regardless of chipper type. A sharp knife set can process between 200 and 1,500 m3 loose chips before getting dull. Disposable knives last longer and are cheaper to manage than standard re-usable knives. [Copyright &y& Elsevier]

Abstract: Significant quantities of woody biomass from the tops of trees and larger woody ‘waste’ pieces that fall outside existing sawlog and pulpwood specifications are left on site post final harvest in Australian radiata Pinus radiata (D. Don) (radiata pine) plantations. Woody biomass is a potential product for pulp making or energy generation. Commercial use of woody biomass from radiata pine plantations would add extra value to the Australian plantation estate through improved resource utilisation, and potentially reduced post-harvesting silvicultural costs. This study investigated the productivity and cost impact of the harvest and extraction to roadside of woody biomass in an integrated harvest operation in a typical Australian two machine (harvester/processor and forwarder), cut-to-length, clearfall operation in a mature, thinned radiata pine plantation. The harvest operation yielded 23 GMt/ha (5% of the total yield) of woody biomass (known as ‘fibreplus’), 443 GMt/ha of sawlogs and 28 GMt/ha of pulpwood. The mean quantity of biomass left on site was 128 GMt/ha, mainly consisting of branches and needles, sufficient to minimise nutrient loss and protect the soil from erosion. Woodchips derived from the fibreplus product were suitable for kraft pulp making, (when blended in small amounts with clean de-barked roundwood woodchips), and for energy generation. The method trialed with the fibreplus product being produced did not impact harvesting and processing productivity and costs, but extraction was 14% less productive. Through analysis of the productivities of each phase and development of a cost model the harvest and extraction of the fibreplus product was estimated to increase total unit costs by ∼4.9%. [Copyright &y& Elsevier]

Abstract: Nowadays wood chips produced from raw material of inferior quality are mainly used to feed domestic and industrial boilers. For this use, a good chip size distribution and low manufacturing energy consumption are required. Cutting forces are still inaccurately measured during the wood chipping process, which implies the use of oversized chippers' motors. A test bench for chipping wood under reasonably realistic conditions of industrial production is improved by adding an indirect force measurement system with high bandwidth of 3 KHz. The dynamic experimentations give the data needed to compute the curve presenting the vertical component of the cutting force, which is composed of three sections; the first one presents the values of the impact force; the second one is relatively straight and it refers to shear stress in wood; the third section corresponds to the period between two crosscuts. [Copyright &y& Elsevier]

Abstract: The efficiency of adequately chosen and monitored technology during the production of wood chips is shown by the quantity of energy stored within the wood fuel, and in the manufacture and preparation costs per product unit. Several influential material, construction, and technological parameters have to be encountered during the production of wood chips when using a mobile drum chipper. A set of different experiments regarding the production of wood chips using a drum chipper were made in order to find the more suitable combinations of production parameters (technological and constructional) for different types of inputted materials (hard round wood, soft round wood, and branches). By monitoring the energy contents within different kinds of wood chips, it was determined that soft wood biomass having rougher structures and hard wood biomass having finer structures are more suitable for larger systems. Dust particles within the wood fractions are undesirable; however constant forms and size–structures regarding wood chips are welcome. The aim of our research was to build a decision model that would help a user to choose the right combination of parameters on a drum chipper, thus ensuring the production of wood fuel with characteristics close to the desired optimum, yet at minimum production costs. [Copyright &y& Elsevier]

Abstract: An unsteady model is developed for the particle size distribution in fluidized-bed reactors including fragmentation, abrasion, elutriation and the chemical reactions of wood gasification. Based on the assumption of constant conditions (gas composition, temperature, velocity) of the surrounding atmosphere, an analytical solution is developed for the distribution of sizes belonging to the classes of mother and fine particles. It is found that for the typical feed sizes (minimum above 3 × 10−2 mm) and the usual maximum size of fine particles (2.4 × 10−3 mm), the behavior of fine particles is quasi-steady with respect to mother particles. The numerical solution of the quasi-steady formulation of particle population balances is also coupled with a two-phase (bubble and emulsion), three-zone (bed, splash zone and freeboard) model for a bubbling fluidized-bed reactor, giving predictions of the producer gas composition in agreement with measurements for air gasification of wood. [Copyright &y& Elsevier]

Abstract: Wood biomass is turned into industrial fuel through chipping. The efficiency of chipping depends on many factors, including chipper knife wear. Chipper knife wear was determined through a long-term follow-up study, conducted at a waste wood recycling yard. Knife wear determined a sharp drop of productivity (>20%) and a severe decay in product quality. Dry sharpening with a grinder mitigated this effect, but it could not replace proper wet sharpening. Increasing the frequency of wet sharpening sessions determined a moderate increase of knife depreciation cost, but it could drastically enhance machine performance and reduce biomass processing cost. Since benefits largely exceed costs, increasing the frequency of wet sharpening sessions may be an effective measure for reducing overall chipping cost. If the main goal of a chipper operator is to increase productivity and/or decrease fuel consumption, then managing knife wear should be a primary target. [Copyright &y& Elsevier]

Abstract: Past studies have established measures of co-firing potential at varying spatial scales to assess opportunities for renewable energy generation from woody biomass. This study estimated physical availability, within ecological and public policy constraints, and associated harvesting and delivery costs of woody biomass for co-firing in selected power plants of the Northern U.S. Procurement regimes were assessed for direct sources of woody biomass from timberland including logging residues (slash, by-products), small-diameter trees, and integrated harvest (logging residues and small-diameter trees). Concentric woody biomass procurement areas were estimated for each power plant using county-level estimates and varying procurement radii. Delivered fuel cost estimates were calculated for each power plant and procurement regime based on incremental maximum transport distances. Procurement regimes focused on small-diameter trees can potentially produce the most electric power, but are constrained by lower economical transport distances than logging residues. These estimates enabled us to assess which power plants in the Northern U.S. had the highest electricity generation potential. For most procurement regimes, an average power plant co-firing had the potential to replace greater than 30% of coal electricity generation if there was no competition for the feedstock. However, woody biomass resource competition from adjacent co-firing plants could reduce this generation potential to less than 10%. [Copyright &y& Elsevier]

Pinus armandii Franch is a dominant plantation species in northwest China, which is deemed as an important wood bioresource. However, the micromolecule of Pinus armandii Franch is currently not fully utilized. In this study, the micromolecule of extracts and pyrolysis products of Pinus armandii Franch were studied for its active molecular compounds have a good prospect of development and application. The results suggested that Pinus armandii Franch is rich in natural product active molecules and bio-oil and consists of at least 5–10 wt% extracts. The methanol, ethanol, methanol/ethanol extract, and pyrolysis products of Pinus armandii Franch mainly contain aromatic, aliphatic, alkanes, aldehydes, ketones, carboxylic acids and ester compounds. In addition, different extraction methods are beneficial to obtain more types of natural chemical compositions, such as 4′-methoxy-2-hydroxystilbene, 7,8-dihydro-2,4 (1h,3h)-pteridinedione, 9h-pyrido [3,4-b] indole,7-methoxy-1,9-dimethyl- and others, which are also abundant in Pinus armandii Franch. These natural product active molecules and bio-oil as high-grade raw resources could be used as drugs and biomedical active ingredients to develop and utilize in the biological medicine industry, including anti-inflammatory, anti-cancer, and anti-HIV treatments. • Studied the molecules of wood extractives and pyrolysis products of P. armandii wood. • The extract and pyrolysis products of P. armandii wood mainly contained aromatic, aliphatic, alkanes, ester compounds, etc. • The main natural product active molecules of P. armandii wood could be used as drugs and biomedical active ingredients. [ABSTRACT FROM AUTHOR]

Abstract: A commercial drum chipper was fed alternately and piecewise with poplar stems and poplar tops, in order to determine the effect of piece size and tree part on machine performance. Chipping stems required most of the available power (231 kW) delivered by the tractor, whereas chipping tops took about half that much. However, productivity was twice as high with stems, compared to tops (i.e. 25 and 11 t h−1 of oven dry wood, respectively). As a consequence, specific fuel consumption per unit product was 15% lower with stems, compared to tops – i.e. 0.61 and 0.72 L m−3, respectively. Mean feeding speed was 0.37 m s−1 for stems and 0.41 m s−1 for tops, but the difference was not significant (p = 0.1677). Productivity and fuel consumption were strongly related to piece size, but tree part had its own additional effect, independent from size and possibly related to form. When chipping tops it is advisable to feed more pieces at a time, in order to partly compensate for the effect of piece size. Operators expecting to chip primarily small-size materials may acquire special chipper versions with wider drums and additional side rollers, for smoother mass feeding. [Copyright &y& Elsevier]

Abstract: Logging residues present a substantial near term opportunity as a bioenergy feedstock, but contaminants that can reduce their value can be introduced during collection. We studied the use of a trommel screen to reduce ash levels in ground forest harvest residues at time of production. Eight treatments of initial harvest type, grinder size, residue age, and screen usage were applied to southern pine plantation residues in the coastal plain of South Carolina, USA. Using the screen, the average ash levels of screened roundwood and clean chipped residue was reduced from 4.0% to 1.4% and from 11.9% to 6%, respectively. Average energy density increased 2–5% by screening. Without screening the feedstock, large grinder utilization with roundwood residues was 58% while the addition of a trommel screen reduced utilization to 47%. Screened roundwood residues were consistently more costly to produce than unscreened roundwood or screened clean chipped residue with either grinder size under a number of economic and operational scenarios on either a load weight or energy content basis. The screened clean chip systems and the unscreened roundwood material provided the most competitive residue on a cost per unit of energy basis. [Copyright &y& Elsevier]

Abstract: In this article we developed a method to estimate forest biomass availability in a situation with small-scale privately owned forests and applied it to three administrative districts in Southern Germany where the majority of owners is organised in forest owners associations. Based on gross annual increment of regional forest resources we calculated a theoretical potential of above-ground biomass from which we subtracted technical and ecological constraints, e.g. restrictions resulting from conservation needs or nutrient removal. The resulting figure was the bio-technical potential of forest biomass. We then assessed the socio-economic potential of forest biomass by considering recent timber felling rates and log grading of owners. In order to determine market potential we differentiated between self-consumption and marketed timber. We compared the calculated potential and timber utilisation patterns of forest owners, deriving the additional supply potential of forest biomass. Most of the data were obtained by a stratified random interview of 226 private forest owners organised in forest owners associations. Although observed harvest intensity was high there was still a considerable potential for increased use of forest biomass. However, willingness of owners to intensify timber harvesting and to supply fuel wood on the basis of long-term contracts is a restriction to additional mobilisation of wood. [Copyright &y& Elsevier]

Abstract: Brazil has favorable edaphoclimatic conditions for the cultivation of biomass for energy. On the other hand, the country plans to expand its thermal power park using fossil fuels, including coal. This paper estimates the potential of co-firing biomass from energy forests in power plants based on Brazilian coal (low rank coal) from the main deposits in the south of Brazil. The technical limits of adding woody biomass to a boiler with a fluidized bed running on Brazilian coal is evaluated along with the availability of this biomass in the south of Brazil. Findings indicate that the main technical limit for boilers operating with different mixtures of biomass and coal is the alteration in the volume of exhaust gas, which varies depending on the percentages of biomass in the co-firing. The limits for biomass availability were based on environmental sustainability and the economic viability of transport. Results indicate that biomass should be available within a radius of around 120 km, which is equivalent to approximately 4,500,000 ha. Only 0.4% of this area would be required to feed a thermal plant of 600 MWe with 30% biomass. [Copyright &y& Elsevier]

Abstract: This study provides a modeling framework to examine change over time in U.S. forest sector carbon inventory (in U.S. timberland tree biomass and harvested wood products) for alternative projections of U.S. and global timber markets, including wood energy consumption, based on established IPCC/RPA scenarios. Results indicated that the U.S. forest sector''s projected capacities for carbon sequestration could be notably altered by use of forest resources for energy. A scenario with large expansion in U.S. wood energy consumption (16-fold increase by 2060) coupled with high global growth in gross domestic product would convert U.S. timberlands to a substantial carbon emission source by 2050, as timber growing stock inventories would be depleted because of increased biomass energy production. In contrast, the same high growth in the economy coupled with much smaller expansion of U.S. wood biomass energy consumption (less than two-fold increase by 2060) would result in a projected increase in average annual additions to U.S. forest sector carbon by up to four-fold by 2060. Results also indicated that higher cumulative carbon emissions from increased use of wood for energy could be partially offset—over time—by increased forest plantations and more intensive forest management that could be stimulated by the increased use of wood for energy. The modeling framework will enable future use of the USFPM/GFPM market modeling system to evaluate the impacts of forest carbon offset policies on forest carbon and forest products markets, by allowing carbon offset payments to compete in the model with forest products or wood energy for the control and use of available timber resources. [Copyright &y& Elsevier]

Abstract: Rice straw and chestnut wood were heated between 200 and 1000 °C (T CHAR ) to produce Black C ‘thermosequences’. The molecular properties of the charred residues were assessed by pyrolysis-GC/MS to investigate the relation between charring intensity and pyrolysis fingerprint. Samples obtained at T CHAR  > 500 °C (wood) or >700 °C (straw) gave low quality pyrograms and poor reproducibility because of high thermal stability, but pyrolysis-GC/MS allowed to track the thermal degradation of the main biocomponents (polysaccharides, lignin, methylene chain-based aliphatics, triterpenoids, chlorophyll and proteins) in the lower temperature range, mostly occurring between T CHAR 250 and 500 °C. With increasing T CHAR , the charred residues of these biocomponents lose characteristic functional groups, aromatise and finally condense into non-pyrolysable biomass. The proportions of the pyrolysis products of unspecific origin (benzene, toluene, PAHs, etc.), increase with charring intensity, while the ratios that reflect the abundance of alkyl cross-linkages between aromatic moieties (e.g. benzene/toluene, naphthalene/alkylnaphthalene) decrease. These results provide the guidelines to using pyrolysis-GC/MS for the molecular characterisation of different components in Black C and biochar, which is an important parameter for predicting Black C/biochar behaviour in soil. Results are consistent with earlier studies of these samples using the BPCA (benzenepolycarboxylic acid) method and the ring current-induced 13C benzene chemical shift NMR (Nuclear Magnetic Resonance) approach. Pyrolysis-GC/MS provides more information on molecular structures in the low temperature range (T CHAR  ≤ 500 °C) while the BPCA and NMR ring current methods provide more reliable estimations of charring intensity, especially at higher temperatures (T CHAR  ≥ 500 °C). [Copyright &y& Elsevier]

Abstract: Short Rotation Coppice (SRC), which entails managing wood plantations as perennial energy crops on agricultural land, has the potential to contribute significant amounts of wooden biomass to Europe''s energy mix. Yet, uncertainty prevails about the future of key economic variables determining the viability of SRC cultivations. Consequently, agriculturists face challenges when conducting ex-ante economic analyses of SRC projects and measuring performance against the alternative, agricultural crops. This paper scrutinises five key determinants of SRC economic viability: yield level, woodchip market price, subsidies, cost level and opportunity costs for conventional agricultural crops. By utilising site-specific conditions and different future scenarios we provide a comprehensive economic appraisal of SRC plantations for agriculturists. We focus our analysis on Germany. Our results show that SRC plantations are less profitable under the medium scenario when compared with agricultural crops. Notwithstanding, favourable political and economic conditions such as subsidies, lower costs and higher woodchip prices can lead to SRC''s superior profitability. If the German government is serious about improving investments conditions for commercial SRC plantations, we recommend introducing sufficient, efficient and consistent subsidies. [Copyright &y& Elsevier]

Abstract: Wood powder is fine-grained biomass that can be utilised in various ways and has advantages over larger wood particles in certain applications due to smaller size and larger surface area. Present knowledge of the processing and characterisation of pulverised wood is insufficient for the efficient production and utilisation of wood powders. In this research, the effect of the operational parameters of an air classifier mill on the pulverisation process and the properties of the resulting wood powders were studied. Screened and dried Norway spruce sawdust was pulverised to very fine wood powders with median particle sizes in the range of 23 μm–250 μm by changing the revolution speeds of a grinding rotor and classifier wheel. Produced wood powders have various different properties, which are important in the utilisation of the powders. In the production of wood powder from dried Norway spruce sawdust with the air classifier mill, one property can be chosen independently from others, whereupon the others have certain restrictions depending on this first choice. The properties of wood powders depend on the speeds of the classifier wheel and grinding rotor and their interaction effect during processing. Average specific energy consumption depends on the speeds of the classifier and grinding rotor. An increase in the classifier speed was found to decrease the median particle size of the powder and increase the average specific energy consumption of the process. An increase in the speed of the grinding rotor was found to reduce the average specific energy consumption. [Copyright &y& Elsevier]

Abstract: With rising fuel costs and enhanced environmental concerns, the use of renewable energy has been steadily considered and widely expounded as a solution to the challenges of global energy security and climate change. The use of woody biomass, in particular, has received considerable attention for energy production. However, high production and transportation costs can be a barrier to woody biomass utilization in some regions. Identifying or developing cost effective production and transportation systems has become an economically critical issue to expand biomass utilization. We developed an optimization model to solve a truck scheduling problem for transporting four types of woody biomass in western Oregon. For an actual 50-load order size, the truck scheduling model produced significant improvements in solution values within 18 s. The average reductions in transportation cost and total travel time were 18% and 15%, respectively. [Copyright &y& Elsevier]

Abstract: Torrefaction is a thermo-chemical conversion process improving the handling, storage and combustion properties of wood. To save storage space and transportation costs, it can be compressed into fuel pellets of high physical and energetic density. The resulting pellets are relatively resistant to moisture uptake, microbiological decay and easy to comminute into small particles. The present study focused on the pelletizing properties of spruce torrefied at 250, 275 and 300 °C. The changes in composition were characterized by infrared spectroscopy and chemical analysis. The pelletizing properties were determined using a single pellet press and pellet stability was determined by compression testing. The bonding mechanism in the pellets was studied by fracture surface analysis using scanning electron microscopy. The composition of the wood changed drastically under torrefaction, with hemicelluloses being most sensitive to thermal degradation. The chemical changes had a negative impact, both on the pelletizing process and the pellet properties. Torrefaction resulted in higher friction in the press channel of the pellet press and low compression strength of the pellets. Fracture surface analysis revealed a cohesive failure mechanism due to strong inter-particle bonding in spruce pellets as a resulting from a plastic flow of the amorphous wood polymers, forming solid polymer bridges between adjacent particles. Fracture surfaces of pellets made from torrefied spruce possessed gaps and voids between adjacent particles due to a spring back effect after pelletization. They showed no signs of inter-particle polymer bridges indicating that bonding is likely limited to Van der Waals forces and mechanical fiber interlocking. [Copyright &y& Elsevier]

Abstract: Energy utilization from biomass resources has started to attract public attention as a method to reduce CO2 emissions. In this study, the characteristics of syngas production from biomass gasification were investigated in a downdraft gasifier that was combined with a small gas engine system for power generation. Syngas temperatures from the gasifier were maintained at a level of 700–1000 °C. When the air ratio for gasification was 0.3–0.35, the low heating value of syngas was 1100–1200 kcal Nm−3 and the cold gas efficiency 69–72%. Tar concentration in raw syngas was around 3.9–4.4 g Nm−3. Syngas combustion in the gas engine after purification showed that HC concentration was below 200 ppm, and NOx concentration was below 40 ppm in the exhaust gas. [Copyright &y& Elsevier]

Abstract: A new organosolv biomass fractionation process (Clean Fractionation, CF) for the separation of lignocellulosic raw material into cellulose, hemicellulose and lignin has been developed. The lignocellulosic material is separated with a ternary mixture of methyl isobutyl ketone, ethanol and water in the presence of an acid promoter, which selectively dissolves lignin and hemicellulose, leaving cellulose as an undissolved solid. The resulting single phase liquor is treated with water giving an organic phase containing lignin and an aqueous phase containing hemicellulose. For woody feedstocks, the yield of the cellulose fraction across all separations averaged 47.7 wt% (±1.1). Representative separations gave cellulose fractions with average Klason lignin contents of 2.0% at acid concentrations of 0.1 M H2SO4 or greater. Little or no galactose, mannose or arabinose is observed in the cellulose, and at an acid concentration of 0.2 M, average xylose contents as low as 0.22% were observed. Average glucan contents for representative cellulose samples of 92.7% were observed, and rose as high as 98.2% for separations using 0.2 M H2SO4. Glucan contents as high as 97% were also observed if the cellulose was bleached using either a QPD or QPDE sequence. The average yield of the lignin fraction was 18.3 wt%. Representative lignin samples gave an average Klason lignin value of 91% with selected lignin samples exhibiting residual sugar levels of <0.5%. The aqueous hemicellulose fraction contains a higher level of non-sugar components, but can be purified by ion exchange chromatography. [Copyright &y& Elsevier]

Abstract: Torrefaction is a soft thermal process usually applied to cocoa or coffee beans to obtain the Maillard reaction to produce aromatics and enhance the flavour. In the case of biomass the main interest of torrefaction it is to break the fibers. To do so, Thermya company has developed and patented a biomass torrefaction/depolymerisation process called TORSPYD™. It is a homogeneous “soft” thermal process that takes place in an inert atmosphere. The process progressively eliminates the biomass water content transforms a portion of the biomass organic matter and breaks the biomass structure by depolymerisation of the fibers. This produces a high performance solid fuel, called Biocoal, which offers a range of benefits over and above that of normal biomass fuel. To develop such a process, this company has developed two main tools: - a continuous torrefaction laboratory pilot with a capacity to produce 3 – 8 kg/h of torrefied biomass; - a mathematical model dedicated to the design and optimisation of the TORSPYD reactor. The mathematical model is able to describe the chemical and physical processes that take place in the torrefaction column at two different scales, namely: the particle, and the surrounding gas. The model enables the gas temperature profiles inside the column to be predicted, and the results of the model are then validated through experiment in the laboratory pilot. The model also allows us to estimate the thermal power necessary to torrefy any type of biomass for a given moisture content. [Copyright &y& Elsevier]