Woody Feedstocks Research Articles

REPRESENTATIVENESS OF EUROPEAN BIOCHAR RESEARCH: PART I – FIELD EXPERIMENTS

A representativeness survey of existing European Biochar field experiments within the Biochar COST Action TD1107 was conducted to gather key information for setting up future experiments and collaborations, and to minimise duplication of efforts amongst European researchers. Woody feedstock biochar, applied without organic or inorganic fertiliser appears over-represented compared to other categories, especially considering the availability of crop residues, manures, and other organic waste streams and the efforts towards achieving a zero waste economy. Fertile arable soils were also over-represented while shallow unfertile soils were under-represented. Many of the latter are likely in agroforestry or forest plantation land use. The most studied theme was crop production. However, other themes that can provide evidence of mechanisms, as well as potential undesired side-effects, were relatively well represented. Biochar use for soil contamination remediation was the least represented theme; further work is needed to identify which specific contaminants, or mixtures of contaminants, have the potential for remediation by different biochars.

Water quality effects of short-rotation pine management for bioenergy feedstocks in the southeastern United States

Growing interest in renewable and domestically produced energy motivates the evaluation of woody bioenergy feedstock production. In the southeastern U.S., woody feedstock plantations, primarily of loblolly pine (Pinus taeda), would be intensively managed over short rotations (10–12years) to achieve high yields. The primary differences in managing woody feedstocks for bioenergy production vs for pulp/sawtimber production include a higher frequency of pesticide and fertilizer applications, whole-tree removal, and greater ground disturbance (i.e., more bare ground during stand establishment and more frequent disturbance). While the effects of pulp/sawtimber production on water quality are well-studied, the effects of growing short-rotation loblolly pine on water quality and the efficacy of current forestry Best Management Practices (BMPs) have not been evaluated for this emerging management system. We used a watershed-scale experiment in a before-after, control-impact design to evaluate the effects of growing loblolly pine for bioenergy on water quality in the Upper Coastal Plain of the southeastern U.S. Intensive management for bioenergy production and implementation of current forestry BMPs occurred on ∼50% of two treatment watersheds, with one reference watershed in a minimally managed pine forest. Water quality metrics (nutrient and pesticide concentrations) were measured in stream water, groundwater, and interflow (i.e., shallow subsurface flow) for a two-year pre-treatment period, and for 3.5years post-treatment. After 3.5years, there was little change to stream water quality. We observed a few occurrences of saturated overland flow, but sediments and water dissipated within the streamside management zones in over 75% of these instances. Stream nutrient concentrations were low and temporal changes mainly reflected seasonal patterns in nitrogen cycling. Nitrate concentrations increased in groundwater post-treatment to <2mgNL−1, and these concentrations were below the U.S. drinking water standard (10mgNL−1). Applied pesticides were almost always below detection in streams and groundwater. Overall, these findings highlight that current forestry BMPs can protect stream water quality from intensive pine management for bioenergy in the first 3.5years. However, groundwater quality and transit times need to be considered in these low-gradient watersheds of the southeastern U.S. that are likely to become an important location for woody bioenergy feedstock production.

Biotechnology for bioenergy dedicated trees: meeting future energy demands

With the increase in human demands for energy, purpose-grown woody crops could be part of the global renewable energy solution, especially in geographical regions where plantation forestry is feasible and economically important. In addition, efficient utilization of woody feedstocks would engage in mitigating greenhouse gas emissions, decreasing the challenge of food and energy security, and resolving the conflict between land use for food or biofuel production. This review compiles existing knowledge on biotechnological and genomics-aided improvements of biomass performance of purpose-grown poplar, willow, eucalyptus and pine species, and their relative hybrids, for efficient and sustainable bioenergy applications. This includes advancements in tree in vitro regeneration, and stable expression or modification of selected genes encoding desirable traits, which enhanced growth and yield, wood properties, site adaptability, and biotic and abiotic stress tolerance. Genetic modifications used to alter lignin/cellulose/hemicelluloses ratio and lignin composition, towards effective lignocellulosic feedstock conversion into cellulosic ethanol, are also examined. Biotech-trees still need to pass challengeable regulatory authorities' processes, including biosafety and risk assessment analyses prior to their commercialization release. Hence, strategies developed to contain transgenes, or to mitigate potential transgene flow risks, are discussed.

The influence of catalysts on biofuel life cycle analysis (LCA)

Catalysts play an important role in biofuel production but are rarely included in biofuel life cycle analysis (LCA). In this work, we estimate the cradle-to-gate energy consumption and greenhouse gas (GHG) emissions of Pt/γ-Al2O3, CoMo/γ-Al2O3, and ZSM-5, catalysts that could be used in processes to convert biomass to biofuels. We also consider the potential impacts of catalyst recovery and recycling. Integrating the energy and environmental impacts of CoMo/γ-Al2O3 and ZSM-5 into an LCA of renewable gasoline produced via in-situ and ex-situ fast pyrolysis of a blended woody feedstock revealed that the ZSM-5, with cradle-to-gate GHG emissions of 7.7kg CO2e/kg, could influence net life-cycle GHG emissions of the renewable gasoline (1.7 gCO2e/MJ for the in-situ process, 1.2 gCO2e/MJ for the ex-situ process) by up to 14% depending on the loading rate. CoMo/γ-Al2O3 had a greater GHG intensity (9.6kg CO2e/kg) than ZSM-5, however, it contributed approximately only 1% to the life-cycle GHG emissions of the renewable gasoline because of the small amount of this catalyst needed per kg of biofuel produced. Given that catalysts can contribute significantly to biofuel life-cycle GHG emissions depending on the GHG intensity of their production and their consumption rates, biofuel LCAs should consider the potential influence of catalysts on LCA results.

Advances in Genetic Manipulation of Lignocellulose to Reduce Biomass Recalcitrance and Enhance Biofuel Production in Bioenergy Crops

Lignocellulose biomass derived from plant cell walls is a rich source of biopolymers for the production of biofuels. Biomass recalcitrance is the noticeable and main features of lignocellulose which can reduces by genetic modification of plant cell wall. The aim of the present review is to provide the reader a new insight for enhancing biomass yield and biofuels production. This can be issued by focusing on major perennial grasses, cereal crops and woody feedstock which have high biomass yield or large biomass residues and also the effects of distinctive cell wall polymers (cellulose, hemicellulose, lignin, and pectin) on the enzymatic saccharification of biomass under different pretreatments. Moreover the present review paper will also major gene candidates which are involved plant cell wall biosynthesis, degradation and modification for improving biomass yield and digestibility in transgenic plants and genetic mutants.

Field-to-Fuel Performance Testing of Lignocellulosic Feedstocks for Fast Pyrolysis and Upgrading: Techno-economic Analysis and Greenhouse Gas Life Cycle Analysis

This work shows preliminary results from techno-economic analysis and life cycle greenhouse gas analysis of the conversion of seven (7) biomass feedstocks to produce liquid transportation fuels via fast pyrolysis and upgrading via hydrodeoxygenation. The biomass consists of five (5) pure feeds (pine, tulip poplar, hybrid poplar, switchgrass, corn stover) and two blends. Blend 1 consists of equal weights of pine, tulip poplar, and switchgrass, and blend 2 is 67% pine and 33% hybrid poplar. Upgraded oil product yield is one of the most significant parameters affecting the process economics, and is a function of both fast pyrolysis oil yield and hydrotreating oil yield. Pure pine produced the highest overall yield, while switchgrass produced the lowest. Interestingly, herbaceous materials blended with woody biomass performed nearly as well as pure woody feedstock, suggesting a nontrivial relationship between feedstock attributes and production yield. Production costs are also highly dependent upon hydrotreat...

Integrating a Biorefinery into an Operating Kraft Mill

Kraft pulp and paper mills have several advantages for serving the emerging biorefinery industry as a source of raw materials. This review examines technologies for producing liquid biofuels, chemicals, and advanced materials from woody feedstocks to generate new sources of revenue. Market pull comes in part from government policies that drive substitution of petroleum-based products with biobased equivalents. Kraft mills have ample networks to supply feedstocks, whether these are forest residues or byproduct side streams. Pulp mills are well suited to expand sufficiently to accommodate production of value added platform chemicals that are in demand because of brand owner sustainability commitments.

Effects of Torrefaction Temperature on Pyrolysis Vapor Products of Woody and Herbaceous Feedstocks

A variety of hardwood, softwood, and herbaceous feedstocks (oak, southern yellow pine mix, loblolly pine, pinyon–juniper mix, and switchgrass) were each torrefied at 200, 250, and 300 °C. Each of the feedstocks was pyrolyzed and the resulting vapors were analyzed with a molecular beam mass spectrometer (py-MBMS). Compositional analysis was used to measure the total lignin content of three of the feedstocks (southern yellow pine, softwood; oak, hardwood; and switchgrass, herbaceous) before and after torrefaction at 300 °C, and large differences in the fraction of lignin lost during torrefaction were found between feedstocks, with oak having the largest decrease in lignin during torrefaction and switchgrass having the least. It is hypothesized that these differences in the thermal degradation are due to, in part, the different ratios of S, G, and H lignins in the feedstocks. Additionally, the torrefaction of kraft lignin was studied using thermogravimetric analysis coupled with Fourier transform infrared sp...

Use of linear programming to ‐optimize the social, −environmental, and economic impacts of using woody feedstocks for pellet and ‐torrefied pellet production

AbstractLinear programming was used to optimize the economic, environmental, and social impacts of forest biomass used for bioenergy production. Sixteen scenarios (combinations of feedstocks, products, markets, and end use) were studied. Two feedstocks (roundwood and wood residues), two densified bioenergy products (white pellet, torrefied pellet), two markets (domestic, international), and two end uses (power generation, district heating) were evaluated. The social, environmental, and economic sustainability attributes were quantified and monetized using peer‐reviewed literature to analyze the trade‐offs. Using the economic criteria alone, the model showed that the best solution was use of 70% roundwood and 30% forest residue feedstock to produce torrefied pellets (TP) sold for district heating in the EU. The model predicts $5.4 million annual profit which is driven by the use of lower cost forest residue feedstocks, and relatively higher prices for the heating market in the EU. Inclusion of all three sustainability attributes led to a different optimized solution. TP produced from roundwood and sold to the EU market for heating was the optimum, due to the social benefits derived from increased local income to landowners and reduced shipping costs. It also had added benefits of reductions in emissions across the transportation system on an energy basis. TP consistently had higher social benefits than WP due to the need for more biomass per unit of final product, and providing more local jobs and income from feedstock production. The increasing costs of carbon emissions increased the environmental benefits of TP compared to WP or coal. © 2016 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Promise of combined hydrothermal/chemical and mechanical refining for pretreatment of woody and herbaceous biomass.

Production of advanced biofuels from woody and herbaceous feedstocks is moving into commercialization. Biomass needs to be pretreated to overcome the physicochemical properties of biomass that hinder enzyme accessibility, impeding the conversion of the plant cell walls to fermentable sugars. Pretreatment also remains one of the most costly unit operations in the process and among the most critical because it is the source of chemicals that inhibit enzymes and microorganisms and largely determines enzyme loading and sugar yields. Pretreatments are categorized into hydrothermal (aqueous)/chemical, physical, and biological pretreatments, and the mechanistic details of which are briefly outlined in this review. To leverage the synergistic effects of different pretreatment methods, conducting two or more pretreatments consecutively has gained attention. Especially, combining hydrothermal/chemical pretreatment and mechanical refining, a type of physical pretreatment, has the potential to be applied to an industrial plant. Here, the effects of the combined pretreatment (combined hydrothermal/chemical pretreatment and mechanical refining) on energy consumption, physical structure, sugar yields, and enzyme dosage are summarized.

Detailed mapping of the mass and energy balance of a continuous biomass torrefaction plant

Biomass torrefaction was tested on pilot scale (50 kg h−1 throughput) for 3 types of wood: spruce, ash and willow at torrefaction temperatures of 250 °C–265 °C. Quantitative analysis of process streams was accomplished by utilising on- and off-line analytical methods.The data obtained from the pilot tests could be very well translated into large-scale operations. A theoretical overall thermal efficiency of 88–89% was calculated for a large-scale heat-integrated torrefaction process that uses wet woody feedstock containing a mass fraction of 45% moisture.These results show that a pilot plant is most suitable not only for exploration of (new) feedstocks but also for generating experimental data that provide valuable information for the design of full-scale plants. The detailed mapping of the mass and energy balances presented in this work can be used further as input for process optimisation, evaluation of commercial viability and techno-economic analyses which can further help in up-scaling and commercialisation of the torrefaction technology.

A secretomic view of woody and nonwoody lignocellulose degradation by Pleurotus ostreatus.

BackgroundPleurotus ostreatus is the second edible mushroom worldwide, and a model fungus for delignification applications, with the advantage of growing on woody and nonwoody feedstocks. Its sequenced genome is available, and this gave us the opportunity to perform proteomic studies to identify the enzymes overproduced in lignocellulose cultures.ResultsMonokaryotic P. ostreatus (PC9) was grown with poplar wood or wheat straw as the sole C/N source and the extracellular proteins were analyzed, together with those from glucose medium. Using nano-liquid chromatography coupled to tandem mass spectrometry of whole-protein hydrolyzate, over five-hundred proteins were identified. Thirty-four percent were unique of the straw cultures, while only 15 and 6 % were unique of the glucose and poplar cultures, respectively (20 % were produced under the three conditions, and additional 19 % were shared by the two lignocellulose cultures). Semi-quantitative analysis showed oxidoreductases as the main protein type both in the poplar (39 % total abundance) and straw (31 %) secretomes, while carbohydrate-active enzymes (CAZys) were only slightly overproduced (14–16 %). Laccase 10 (LACC10) was the main protein in the two lignocellulose secretomes (10–14 %) and, together with LACC2, LACC9, LACC6, versatile peroxidase 1 (VP1), and manganese peroxidase 3 (MnP3), were strongly overproduced in the lignocellulose cultures. Seven CAZys were also among the top-50 proteins, but only CE16 acetylesterase was overproduced on lignocellulose. When the woody and nonwoody secretomes were compared, GH1 and GH3 β-glycosidases were more abundant on poplar and straw, respectively and, among less abundant proteins, VP2 was overproduced on straw, while VP3 was only found on poplar. The treated lignocellulosic substrates were analyzed by two-dimensional nuclear magnetic resonance (2D NMR), and a decrease of lignin relative to carbohydrate signals was observed, together with the disappearance of some minor lignin substructures, and an increase of sugar reducing ends.ConclusionsOxidoreductases are strongly induced when P. ostreatus grows on woody and nonwoody lignocellulosic substrates. One laccase occupied the first position in both secretomes, and three more were overproduced together with one VP and one MnP, suggesting an important role in lignocellulose degradation. Preferential removal of lignin vs carbohydrates was shown by 2D NMR, in agreement with the above secretomic results.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0462-9) contains supplementary material, which is available to authorized users.

Predicting Properties of Gas and Solid Streams by Intrinsic Kinetics of Fast Pyrolysis of Wood

Pyrolysis has the potential to create a biocrude oil from biomass sources that can be used as fuel or as feedstock for subsequent upgrading to hydrocarbon fuels or other chemicals. The product distribution/composition, however, is linked to the biomass source. This work investigates the products formed from pyrolysis of woody biomass with a previously developed chemical kinetics model. Different woody feedstocks reported in prior literature are placed on a common basis (moisture, ash, fixed carbon free) and normalized by initial elemental composition through ultimate analysis. Observed product distributions over the full devolatilization range are explored, reconstructed by the model, and verified with independent experimental data collected with a microwave-assisted pyrolysis system. These trends include production of permanent gas (CO, CO2), char, and condensable (oil, water) species. Elementary compositions of these streams are also investigated. Close agreement between literature data, model predictio...

Sources of Biomass Feedstock Variability and the Potential Impact on Biofuels Production

Terrestrial lignocellulosic biomass has the potential to be a carbon neutral and domestic source of fuels and chemicals. However, the innate variability of biomass resources, such as herbaceous and woody materials, and the inconsistency within a single resource due to disparate growth and harvesting conditions, presents challenges for downstream processes which often require materials that are physically and chemically consistent. Intrinsic biomass characteristics, including moisture content, carbohydrate and ash compositions, bulk density, and particle size/shape distributions are highly variable and can impact the economics of transforming biomass into value-added products. For instance, ash content increases by an order of magnitude between woody and herbaceous feedstocks (from ∼0.5 to 5 %, respectively) while lignin content drops by a factor of two (from ∼30 to 15 %, respectively). This increase in ash and reduction in lignin leads to biofuel conversion consequences, such as reduced pyrolysis oil yields for herbaceous products as compared to woody material. In this review, the sources of variability for key biomass characteristics are presented for multiple types of biomass. Additionally, this review investigates the major impacts of the variability in biomass composition on four conversion processes: fermentation, hydrothermal liquefaction, pyrolysis, and direct combustion. Finally, future research processes aimed at reducing the detrimental impacts of biomass variability on conversion to fuels and chemicals are proposed. © 2015 Battelle Energy Alliance, LLC, contract manager for Idaho National Laboratory.

Effects of moisture content on wind erosion thresholds of biochar

Biochar, i.e. pyrolysed biomass, as a soil conditioner is gaining increasing attention in research and industry, with guidelines and certifications being developed for biochar production, storage and handling, as well as for application to soils. Adding water to biochar aims to reduce its susceptibility to become air-borne during and after the application to soils, thereby preventing, amongst others, human health issues from inhalation. The Bagnold model has previously been modified to explain the threshold friction velocity of coal particles at different moisture contents, by adding an adhesive effect. However, it is unknown if this model also works for biochar particles. We measured the threshold friction velocities of a range of biochar particles (woody feedstock) under a range of moisture contents by using a wind tunnel, and tested the performance of the modified Bagnold model. Results showed that the threshold friction velocity can be significantly increased by keeping the gravimetric moisture content at or above 15% to promote adhesive effects between the small particles. For the specific biochar of this study, the modified Bagnold model accurately estimated threshold friction velocities of biochar particles up to moisture contents of 10%.

Effects of logging and coarse woody debris harvest on lepidopteran communities in the eastern deciduous forest of North America

Expansion of biomass energy production using woody feedstocks is being accomplished through post-timber harvest removal of coarse woody debris > 10 cm. The effect of this management on forest Lepidoptera is poorly known. The present study aimed to determine whether forest lepidopteran diversity and species composition were affected by two silvicultural disturbances: timber harvest and post-logging removal of coarse woody debris > 10.0 cm in diameter. In 2014, Lepidoptera were sampled from nine forest stands subject to one of three management treatments: control (no manipulation at all), clear cut and partial retention of coarse woody debris (80% removal), and clear cut and complete removal of coarse woody debris. As expected, species richness and composition were significantly impacted by timber harvest. Subsequent removal of 80% or 100% coarse woody debris, however, did not affect specialists, detritivores and pollinators. The absence of an effect as a result of the removal of coarse woody debris could be a result of the limited number of replicate stands, small stand size and the limited range of retention treatments. We suggest, however, that retention of fine woody debris with a diameter < 10.0 cm and inclusion of unlogged stands in the forest landscape maintains some of the habitat elements necessary for Lepidoptera.

Physicochemical and sorptive properties of biochars derived from woody and herbaceous biomass

It is unclear how the properties of biochar control its ability to sorb metals. In this work, physicochemical properties of a variety of biochars, made from four types of feedstock at three pyrolysis temperatures (300, 450 and 600°C) were compared to their ability to sorb arsenic (As) and lead (Pb) in aqueous solutions. Experimental results showed that both feedstock types and pyrolysis temperature affected biochar’s production rate, i.e., ratio of mass of biochar and biomass, thermal stability, elemental composition, non-combustible component (NCC) content, pH values, surface areas and thus their sorption ability to the two metals in aqueous solution. In general, the high temperature biochars had low O/C and H/C ratios, were more carbonized with larger surface area, and were more concentrated with alkaline cations. In addition, biochars made from woody feedstocks had larger surface area, but lower NCC contents than that made from grasses under the same conditions. Although all the tested biochars removed both As and Pb from aqueous solutions, they showed different sorption abilities because of the variations in properties. Statistical analyses suggested that feedstock type affected the sorption ability of the biochars to both As and Pb significantly (p<0.001). Pyrolysis temperature, however, showed little influence on biochar sorption of Pb in aqueous solutions. Statistical analyses also showed that electrostatic interaction played an important role in controlling the sorption of both As(V) and Pb(II) onto the biochar. Other mechanisms, such as precipitation and surface complexation, could also control the sorption of Pb(II) onto the biochars.

Assessing Site Availability of Aspen and Northern Hardwoods for Potential Feedstock Development in Michigan: A Case Study

The importance of wood and wood byproducts as biomass feedstocks is of increasing interest as a source of ethanol and electricity. Second generation woody feedstock sources in Michigan, e.g., hybrid poplar and hybrid willow (Populus spp.), and native forests, particularly aspen and northern hardwoods, are a potential source of woody biomass for these uses. This study provides a geographic information system (GIS) framework for assessing the current spatial extent of aspen and northern hardwoods) and their proximity to roads. Additionally, the potential for expanding the area of these feedstock sources based on pre-European settlement vegetation cover is assessed. Utilizing GIS technology to compile, edit and analyze available geospatial data (e.g., present day and pre-European settlement land use/cover, soils, road infrastructure, and land ownership) for counties located in the eastern half of the Upper Peninsula and northern half of the Lower Peninsula of Michigan provides a robust framework for various management scenarios to be evaluated in a cost effective manner and foster better decision making.

Scale-Up of Ionic Liquid-Based Fractionation of Single and Mixed Feedstocks

Lignocellulosic biorefineries have tonnage and throughput requirements that must be met year round, and there is no single feedstock available in any given region that is capable of meeting the price and availability demands of the biorefineries. Ionic liquid (IL) pretreatment with certain ILs is receiving significant attentions as a potential process that enables fractionation of a wide range of feedstocks and produces high yields of fermentable sugars suitable for biofuel production. Building on the large-scale demonstration of a single herbaceous feedstock (switchgrass), this work extends scale-up of IL pretreatment to woody (eucalyptus) and mixed feedstock (mixtures of two) by 30-fold, relative to the bench scale (6 vs 0.2 L) at 10 % solid loading. The mixed feedstock recovered similar yields of glucan (99.7 %), xylan (62.8 %), and lignin (59.9 %) as switchgrass and eucalyptus at 6-L scale operation, and results of all three feedstocks are better than those obtained from small-scale studies. By integrating the process of IL pretreatment with efficient and scalable homogenization, washing, and product recovery system, IL contents in the recovered materials were decreased to 0.2 %, mitigating the risk to downstream enzymatic saccharification and microbial fermentation. Results indicate that mixed feedstock are viable and valuable resource to consider when assessing biomass availability and affordability for lignocellulosic biorefineries. This scale-up evaluation demonstrates that IL pretreatment technology is feedstock agnostic and can be effectively scaled to larger operations.

Assessing the potential of biochar and charcoal to improve soil hydraulic properties in the humid Ethiopian Highlands: The Anjeni watershed

Biochar has shown promise for restoring soil hydraulic properties. However, biochar production could be expensive in the developing world, while charcoal is widely available and cheap. The objective of this study is therefore to investigate whether some of the charcoal made in developing countries can also be beneficial for improving soil hydraulic properties, and explore whether charcoal could potentially restore the degraded African soils. Laboratory and field experiments were conducted in the Anjeni watershed in the Ethiopian highlands, to measure soil physical properties including soil moisture retention and infiltration rates. Soils were dominantly clayey with pH in the acidic range, low organic carbon content, and steady infiltration rates ranging between 2 and 36mm/h. Incorporation of woody feedstock (Acacia, Croton, and Eucalyptus) charcoals significantly decreased moisture retention at lower tensions (10 and 30kPa), resulting in an increase in relative hydraulic conductivity coefficients at these tensions. While wood (oak) biochar decreased moisture retention at low tensions, corn biochar increased retention, but effects were only slight and not significant. Surprisingly, available water content was not significantly affected by any of the amendments. Overall findings suggest that wood charcoal amendments can improve soil hydraulic properties of degraded soils, thereby potentially reducing runoff and erosion.