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Looking for new alternative raw materials is one of the key issues in line with a bioeconomy approach, particularly for particleboard manufacturing. In this framework, this paper presents a comparison of some physico-mechanical properties and the formaldehyde contents of particleboards made with 30% substitution of grass biomass from six perennial grass species. Our studies indicate relatively high values of mechanical properties for particleboards made with the addition of biomass from grasses with the C4 photosynthetic pathway: Miscanthus x giganteus and switchgrass (Panicum virgatum). Boards made with the addition of biomass from grasses with the C3 photosynthetic pathway—tall wheatgrass (Elymus elongatus), tall fescue (Festuca arundinacea), and perennial ryegrass (Lolium perenne)—gave lower values of mechanical properties. The opposite results were obtained in the case of the formaldehyde content: the lowest value was measured for particleboards made with the addition of tall fescue biomass (0.1% less than the control), and the highest for switchgrass (0.9% greater than the control) and cordgrass (3.2% greater than the control). Future research should address the optimization of the manufacturing process of particleboards from perennial grasses, taking into account the needs and technical possibilities of the wood industry sector. [ABSTRACT FROM AUTHOR]

Summary: Improving plant biomass yield and/or feedstock quality for highly efficient lignocellulose conversion has been the main research focus in genetic modification of switchgrass (Panicum virgatum L.), a dedicated model plant for biofuel production. Here, we proved that overexpression of miR396 (OE‐miR396) leads to reduced plant height and lignin content mainly by reducing G‐lignin monomer content. We identified nineteen PvGRFs in switchgrass and proved thirteen of them were cleaved by miR396. MiR396‐targeted PvGRF1, PvGRF9 and PvGRF3 showed significantly higher expression in stem. By separately overexpressing rPvGRF1, 3 and 9, in which synonymous mutations abolished the miR396 target sites, and suppression of PvGRF1/3/9 activity via PvGRF1/3/9‐SRDX overexpression in switchgrass, we confirmed PvGRF1 and PvGRF9 played positive roles in improving plant height and G‐lignin content. Overexpression of PvGRF9 was sufficient to complement the defective phenotype of OE‐miR396 plants. MiR396‐PvGRF9 modulates these traits partly by interfering GA and auxin biosynthesis and signalling transduction and cell wall lignin, glucose and xylan biosynthesis pathways. Moreover, by enzymatic hydrolysis analyses, we found that overexpression of rPvGRF9 significantly enhanced per plant sugar yield. Our results suggest that PvGRF9 can be utilized as a candidate molecular tool in modifying plant biomass yield and feedstock quality. [ABSTRACT FROM AUTHOR]

The utilization of polymeric biorenewables for the synthesis of biofuels and essential chemicals is largely obstructed by their recalcitrant structures and complex product distribution. Here, hydrosilane-mediated hydrodeoxygenation (HDO) of the furanic mixture 5-hydroxymethylfurfural (HMF) and 5-chloromethylfurfural (CMF), directly derived from cellulosic biomass, can be enabled by heterogeneous Pd-catalyzed dechlorination to exclusively give the biofuel 2,5-dimethylfuran (DMF) in a high overall yield of 72%. Kinetic and isotope labeling studies supported by computational calculations explicitly elucidate the reaction pathways. The initial dechlorination of CMF into acidic species promotes the rapid in situ formation of relatively stable acetalized and etherified furanic intermediates, which not only greatly accelerate the reactivity of the entire HDO process (TOF: up to 1200 h−1), but are also able to significantly get rid of unwanted side reactions. Importantly, this catalytic system can also be applied for the upgrade of various chlorinated carboxides to produce ortho-, meta- and para-substituted arenes with satisfactory yields of 82–99% at 25–45 °C, and the used commercial Pd/C catalyst is highly recyclable. [ABSTRACT FROM AUTHOR]

Highlights • N rate exhibited non-significant effects on biofuel feedstock quality indices but significantly improved TEY. • CP content and protein yield as forage quality increased with application of 60 kg N ha−1. • Late summer harvest provides best quality forage while early fall harvest supplied more TEY. • Soil NO 3 − content at early fall harvest increased with increasing N rate. • A lower N rate was suitable to produce quality forage or feedstock and to avoid NO 3 − leaching on sandy soil. Abstract Switchgrass (Panicum virgatum L.) is a perennial warm-season grass which has great potential as a forage or bioenergy crop in marginal land. This study was conducted to determine whether nitrogen (N) fertilization could affect biomass quality of switchgrass harvested in late summer and early fall. The effects of four N fertilizer application rates (0, 60, 120, and 240 kg N ha−1) and two harvest times (late summer and early fall) on the quality components of forage and biofuel feedstock and theoretical ethanol yield (TEY) were investigated on a sandy wasteland (Aridisol) in Inner Mongolia, China during the growing seasons of 2015 and 2016. Soil NO 3 − content was also examined in response to N application rates. Application of 60 kg N ha−1 significantly increased switchgrass crude protein (CP) content, protein yield, and TEY (p < 0.05), but did not affect other quality parameters of forage and biofuel feedstock. Compared with the late summer harvest, CP content and protein yield were significantly lower, while TEY was significantly higher in the early fall harvest (p < 0.05); however, cellulose, hemicellulose, and ash contents showed no significant differences between the two harvest times. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents were significantly lower for harvest in early fall than in late summer (p < 0.05). Soil NO 3 − content in early fall harvest increased significantly with increasing N application rate (p < 0.05), and was lower than that in the switchgrass green-up stage. These findings together with our results on biomass yield and apparent soil N balance suggest that a lower rate of N application appears sufficient to produce good quality forage as well as biomass without negatively affecting feedstock quality, while avoiding the risk of NO 3 − loss via leaching on a sandy soil. Switchgrass forage quality would be high during summer in terms of CP content, although delaying harvest until fall or even after a killing frost could provide better quality feedstock for bioenergy production. [ABSTRACT FROM AUTHOR]

Abstract: Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small‐scale and short‐term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long‐term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field‐scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm‐scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM‐ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country. [ABSTRACT FROM AUTHOR]

Within-field spatial variability reduces growers’ return on investment and overall productivity while potentially increasing negative environmental impacts through increased soil erosion, nutrient runoff, and leaching. The hypothesis that integrating energy crops into non-profitable segments of agricultural fields could potentially increase grain yield and biomass feedstock production was tested in this study using a statewide analysis of predominantly corn- and soy-producing counties in Iowa. Basic and rigorous controls on permissible soil and soil-carbon losses were imposed on harvest of crop residues to enhance year-to-year sustainability of crop and residue production. Additional criteria limiting harvesting costs and focus on large-area subfields for biomass production were imposed to reduce the impacts of energy crop integration on grain production. Model simulations were conducted using 4 years (2013-2016) of soil, weather, crop yield, and management practice data on all counties in Iowa. Miscanthus (Miscanthus x giganteus), switchgrass (Panicum virgatum), and crop-residue-based bioenergy feedstock systems were evaluated as biomass. Average energy crop and plant residue harvesting efficiencies were estimated at 50 and 60%, respectively. Because of higher potential yields, average logistics costs for miscanthus-based biomass production were 15 and 23% lower than switchgrass-based and crop residue-based biomass productions, respectively, under basic sustainability controls, and 17 and 26% lower under rigorous sustainability controls. Subfield shape, size, area, and harvest equipment size were the dominant factors influencing harvesting cost and efficiency suggesting that in areas where subfields are predominantly profitable or harvesting efficiencies low, other options such as prairie strips, buffer zones around fields, and riparian areas should be investigated for more profitable biomass production and sustainable farming systems. [ABSTRACT FROM AUTHOR]

Organic fertilizers can improve soil health while providing nutrients for perennial grass growth for bioenergy feedstock, particularly under marginal soil conditions. The impact of organic fertilizer application on perennial grass composition needs clarification. Our objective was to evaluate feedstock composition, and N, P, and K dynamics of switchgrass ( Panicum virgatum L.), tall fescue [ Lolium arundinaceum (Schreb.)], and reed canarygrass ( Phalaris arundinacea L.) provided with either inorganic or organic fertilizer sources. Grasses were established on a sandy soil and a clay soil at the Cornell University Willsboro Research Farm in Willsboro, NY. The experiment was a split-split plot randomization of a randomized block design with six replicates. Sites were whole plots, grass species were subplots, and fertility treatments were sub-subplots. Six treatments were (1) 168 kg ha of N fertilizer for cool-season grasses; 84 kg ha for switchgrass, (2) 56 kg ha of 0-46-0 P fertilizer plus N (#1), (3) 112 kg ha of 0-0-60 K fertilizer plus N (#1), (4) 89.6 Mg dairy manure ha, (5) 44.8 Mg dairy manure compost ha, and (6) a control without fertilizer. Organic fertilizers produced a net positive P and K balance, while other treatments had negative balances. Organic fertilizer treatments resulted in lower lignin and gross energy values, and higher total ash and Cl, compared to inorganic fertilizer treatments. Switchgrass biomass had higher fiber and gross energy, lower total ash, and much lower Cl content under organic fertilizer applications than cool-season grasses, making switchgrass a more desirable feedstock regardless of conversion process. [ABSTRACT FROM AUTHOR]

Integrated landscape management has emerged in recent years as a methodology to integrate the environmental impacts of various agricultural practices along with yield and profitability in a variety of cropping systems. In this study, the Landscape Environmental Assessment Framework (LEAF), a decision support toolset for use in integrated landscape management and developed at Idaho National Laboratory, was used to evaluate the profitability of grain-producing subfields, to determine the efficacy of sustainably harvesting residual biomass after grain harvest, and to determine the efficacy of integrating bioenergy crops into grain-producing landscapes to enhance farmer profitability. Three bioenergy crops, sorghum, switchgrass, and miscanthus, were integrated into non-profitable subfields in four US counties. The manuscript describes in detail the material and methods used to define crop rotations, land management units and practices, subfield units and productivity, grain profitability, sustainability criteria, energy crop integration, and feedstock cost estimation. With the integration of bioenergy crops, the overall annual biomass production rates in the four counties could be increased by factors ranging from 0.8 to 21, depending on the energy crop and county, over the annual residue biomass production rates. By modeling the harvesting of residual biomass and energy crops using geo-referenced, precision harvesting equipment and optimal harvesting paths on individual subfields, the average logistics costs including harvesting of both residual biomass and energy crops were observed to fall well below US DOE's 2017 goals for biomass feedstock price of US$84/ton or US$92.6/dry Mg. Miscanthus, grown in counties in Ohio and Kansas, provided the maximum potential, among the three energy crops considered, for increment in biomass production and also posed maximum threat to the grain production. Considerable variability was observed in the harvesting and total costs because of the size, shape, and productivity of individual subfields. It was shown that variability in the harvesting costs could be used to down-select non-profitable farms with low harvesting costs and high residue and bioenergy crop yields and to reduce the negative impacts of bioenergy crop integration into croplands on grain production. The results of the assessment suggest that (1) the potential to produce biomass is considerably enhanced when non-profitable grain-producing subfields are replaced by bioenergy crops and (2) the subfield-scale integrated landscape assessment provides a defensible methodology to directly address individual farmer's profitability, sustainability, and environmental stewardship. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass can be a significant source of renewable clean energy with continued improvement in biomass yield and bioconversion strategies. In higher plants, the leaf blade is the central energy convertor where solar energy and CO2 are assimilated to make the building blocks for biomass production. Here we report that introducing the leaf blade development regulator STENOFOLIA (STF), a WOX family transcription factor, into the biofuel crop switchgrass, significantly improves both biomass yield and sugar release. We found that STF overexpressing switchgrass plants produced approximately 2-fold more dry biomass and release approximately 1.8-fold more solubilized sugars without pretreatment compared to controls. The biomass increase was attributed mainly to increased leaf width and stem thickness, which was also consistent in STF transgenic rice and Brachypodium, and appeared to be caused by enhanced cell proliferation. STF directly binds to multiple regions in the promoters of some cytokinin oxidase/dehydrogenase (CKX) genes and represses their expression in all three transgenic grasses. This repression was accompanied by a significant increase in active cytokinin content in transgenic rice leaves, suggesting that the increase in biomass productivity and sugar release could at least in part be associated with improved cytokinin levels caused by repression of cytokinin degrading enzymes. Our study provides a new tool for improving biomass feedstock yield in bioenergy crops, and uncovers a novel mechanistic insight in the function of STF, which may also apply to other repressive WOX genes that are master regulators of several key plant developmental programs. [ABSTRACT FROM AUTHOR]

If the US mandates for the use of cellulosic biofuels are ultimately enforced, cellulosic feedstock will be demanded. Native switchgrass is a cellulosic feedstock that has been of substantial interest for this purpose because it is widely grown across the USA, it can be grown on marginal cropland and thus compete minimally with food supplies, it has a low carbon footprint, and in many ways, it is a sustainable source of energy. The purpose of the research reported here is to quantify the potential willingness of producers across 358 counties in a 10-state area in North Central USA to produce this biomass. We conducted a contingent valuation survey of randomly selected farm operators in this area. From the more than 1100 responses, we found that the mean reservation price at which respondents were willing to supply switchgrass from their least productive field is a return of about $228 per acre, which translates to about $82 per dry ton. Respondents were somewhat less willing to lease out their land for this purpose, requiring an additional $3.50 per dry ton to be willing to lease. In sub-regions of counties grouped by opportunity cost, mean reservation prices are equivalent to $75 per ton, $82 per ton, and $99 per ton, very close in the first two subregions to the Department of Energy goal of $84 per dry ton delivered to the biorefinery. Thus, prospects appear favorable that substantial fractions of farmers would be willing to supply switchgrass in this area, particularly in the sub-areas with lower land costs. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the impact of incorporating switchgrass samples that have been in long term storage on the development of near-infrared (NIR) multivariate calibration models and their predictive capabilities. Stored material contains more variation in their respective spectral signatures due to chemical changes in the bales with storage time. Partial least squares (PLS) regression models constructed using NIR spectra of stored switchgrass possessed an instability that interfered with the correlation between the spectral data and measured chemical composition. The models were improved using calibration sample sets of equal parts stored and fresh switchgrass to more accurately predict the chemical composition of stored switchgrass. Acceptable correlation values (rcalibration) were obtained using a calibration sample set composed of 25 stored samples and 25 samples of fresh switchgrass for cellulose (0.91), hemicellulose (0.74), total carbohydrates (0.76), lignin (0.98), extractives (0.92), and ash (0.87). Increasing the calibration sample set to 100 samples of equal parts stored to senesced material resulted in statistically increased (p = 0.05) correlations for total carbohydrates (0.89) and ash (0.96). When these models were applied to a separate validation set (equal to 10% of the calibration sample set), high correlation coefficients (r) for predicted versus measured constituent content were observed for cellulose (0.94), total carbohydrates (0.98), lignin (0.91), extractives (0.97), and ash (0.90). For optimization of processing economics, the impact of feedstock storage must be investigated for implementation in conversion processes. While NIR is a well-known high-throughput technique for characterization of senesced switchgrass, the selection of appropriate calibration samples and consequent multivariate models must be taken into careful consideration for NIR application in a biomass storage facility for rapid chemical compositional determination. [ABSTRACT FROM AUTHOR]

Development of viable bioenergy economies will require large increases in biomass feedstock production. Improved methods are needed to quantify production potential based on land availability, land suitability, biomass yield, and cost. We developed such a method and applied it throughout New York State. While maintaining existing forest and agricultural production, we quantified additional sustainable biomass production potential using geospatial and yield modeling that integrates remotely sensed and survey data for land cover, soil type, climate patterns, and crop yields and then applied multiple sustainability constraints. Nearly 680,000 ha with varying quality was found to be available and suitable for new biomass production. Predicted yields ranged from 7.8 to 18.3 Mg/ha for short-rotation willow and 6.9-16.3 Mg/ha for perennial grasses for a total production potential of 8.2 Tg/year. Increased forest harvest could produce an additional 4.3 Tg/year of hardwood and 1.6 Tg/year of softwood. In total, an additional 14.2 Tg/year of biomass for bioenergy could be produced while maintaining existing agricultural and forest production. This new biomass, before processing, would contain energy equivalent to 7.4 % of 2012 New York energy use (3.4 % if converted to ethanol). [ABSTRACT FROM AUTHOR]

Improper management of cattle manure and poultry litter from confined animal farming are usually source of water pollution. However, appropriate application of these products on switchgrass ( Panicum virgatum L.) field can enhance biomass yield and promote nutrient recycling. We evaluated the effects of harvest frequency and nutrient sources on yield and quality of switchgrass for biofuel feedstock. The experiment was carried out at Perkins and Lake Carl Blackwell, Oklahoma, from 2009 to 2011 using split plot design with four replications. The main plot treatments were two harvest frequencies single (June), and twice (June and November). The subplot treatments were nutrient sources: 1) cattle manure (CM), 2) poultry litter (PL), 3) urea (nitrogen at 150 kg ha −1 ), 4) combined chemical fertilizer (nitrogen-P 2 O 5 –K 2 O) with nitrogen at 150 kg ha −1 , P 2 O 5 at 40 kg ha −1 , and K 2 O at 20 kg ha −1 , 5) inter-seeded Crimson clover ( Trifolium incarnatum L.), and 6) control. Mean biomass yield was higher (12.4 Mg ha −1 ) in 2010 than other years possibly due to optimum moisture and temperature in 2010. At Perkins in 2010, application of CM and PL increased biomass yield significantly by 30 and 23% compared with combined chemical fertilizer (12.9 Mg ha −1 ). The effect of nutrient sources on cellulose, hemicellulose and lignin content was not significant at both locations. Cumulative biomass from twice harvest was similar to single harvest except in 2011 due to dry weather after the first cut. The cellulose and lignin content were significantly higher for single harvest compared with twice harvest at both locations. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass in bale form has a low bulk density. Current in-field balers can achieve a bulk density of merely 120 to 180 kg dry matter (DM) m, whereas modern high-compression cutting balers produce up to 230 kg m. Mechanical compression is a straightforward technique to increase the material density, which significantly improves the efficiency of transportation and storage, and simplifies handling. Traditional compression technology mainly produces pellets, but conceivably bales could be compressed to a higher density as well. To design compression machinery in general, it is essential to determine the mechanical properties of biomass under compression and compression energy consumption. In addition, the material rebound percentage after compression is needed to design low-cost containerization methods for highly compressed bales. In this research, we established pressure-bulk density relationships and calculated Poisson's ratio for Miscanthus ( Miscanthus × giganteus, Poaceae/Gramineae) and switchgrass ( Panicum virgatum L. Poacea/Gramineae). We also calculated rebound percentages for Miscanthus in two particle sizes. The results showed that the energy consumption for compression of Miscanthus and switchgrass is low, ranging from 0.01 to 0.05 % of the inherent heating value of the materials. Poisson's ratios of Miscanthus and switchgrass ranged from 0.2 to 0.3 for various particle sizes. The rebound percentage was found as 28 % for unground Miscanthus and 23 % for Miscanthus ground to 6.35-mm particles. A common opinion is that high-level compression of biomass may reduce its energy content. Although in this research some of the biomass was exposed to an extreme pressure of 750 MPa, microscopic imagery revealed no fractions in the cell walls, leading to the conjecture that compression does not negatively impact the conversion potential of the biomass. [ABSTRACT FROM AUTHOR]

Marginal and degraded lands are expected to be important resources in the production of biofuel feedstocks in order to avoid real or perceived competition with food, feed and fiber production. Globally, there are millions of hectares of salt-affected land available for lignocellulosic feedstock production. Greenhouse experiments determined the effects of irrigating with water having different levels of salinity and sodicity on seedling emergence, plant growth, and cation balance in plant tissues in several populations of switchgrass ( Panicum virgatum L.) and prairie cordgrass ( Spartina pectinata Link). The effect of salt stress on seedling emergence was more pronounced in switchgrass than prairie cordgrass with 31 and 15% reduction, respectively, compared with pure water. In a two-season greenhouse pot experiment, aboveground dry biomass production in control treatments was 8 and 21% higher in prairie cordgrass pc17-102 and pc17-109, respectively, than in EG 1102 switchgrass. Switchgrass EG 1102 produced greater biomass than prairie cordgrass populations when irrigated with moderately saline (5 dS m −1 ) water, although differences were not detected with highly saline water (10 dS m −1 ). Switchgrass EG 2101 emergence, plant growth and cation balance were severely affected by increasing levels of salinity. Overall, several prairie cordgrass populations and lowland switchgrass cultivars were found to have good emergence and high biomass production under moderate to high salt stress and may be good candidates for lignocellulosic feedstocks on salt-affected land. [ABSTRACT FROM AUTHOR]

In this research, low-heat alkaline pretreatment was evaluated to determine the extent to which urban landscape waste (yard waste), corn stover, and switchgrass could be codigested under conditions typical of US farm-based anaerobic digestion (AD). Waste heat from combined heat and power (CHP) units associated with AD could make such pretreatment economical. Short-term batch digestion studies and 8-week continuous-feed studies were used to screen and evaluate various pretreatment conditions. Results indicate that maple and oak leaves did not digest well, even with pretreatment. Pretreatment did improve digestion of corn leaves and stalks as well as switchgrass. However, these materials also digested reasonably well even without pretreatment. No digester operational problems were observed during continuous-feed studies of intermittently stirred bench top digesters, but optimal levels of alkali, temperature, and pretreatment time may be specific to the feedstock, particle size, and digester loading rate. Results suggest that some common lignocellulosic biomass materials, such as corn stover and switchgrass, could be successfully codigested in many existing farm-based digesters. Interestingly, without pretreatment, switchgrass digestion improved over 20-fold when digested with seed culture from a dairy digester compared to seed culture from a municipal digester, suggesting that culture acclimation could be as important as pretreatment in improving digestion of specific lignocellulosic feedstocks. [ABSTRACT FROM PUBLISHER]

Biorefineries that plan to use switchgrass exclusively will encounter year-to-year variability in feedstock production. The economic success of the biorefinery will depend in part on the ability of the management team to strategically identify land for conversion from current use to the production of switchgrass enabling a flow of feedstock for the life of the biorefinery. The objective of this research is to determine the optimal quality, quantity, and location of land to lease while considering the spatial and temporal variability of switchgrass biomass yield. A calibrated biophysical simulation model was used to simulate switchgrass biomass yields for 50 years based on historical weather data from 1962 to 2011, for three land capability classes for each of 30 counties. Mathematical programming models were constructed and solved to determine the optimal leasing scheme for each of three strategies for a biorefinery that requires 2,000 Mg/day. As expected, a model based on the assumption that the average yield would be obtained in each year finds that production from land identified for leasing would be insufficient to fulfill the biorefinery's needs in half of the years. In the absence of other sources of biomass, the feedstock shortage would require forced idling of the biorefinery for an average of 29.5 days during these years. Results of a strategy of leasing sufficient land to cover feedstock needs in the worst year from among 50 years for which data are available are compared to that of a strategy enabling year-to-year storage. [ABSTRACT FROM AUTHOR]

The Regional Feedstock Partnership is a collaborative effort between the Sun Grant Initiative (through Land Grant Universities), the US Department of Energy, and the US Department of Agriculture. One segment of this partnership is the field-scale evaluation of switchgrass ( Panicum virgatum L.) in diverse sites across the USA. Switchgrass was planted (11.2 kg PLS ha) in replicated plots in New York, Oklahoma, South Dakota, and Virginia in 2008 and in Iowa in 2009. Adapted switchgrass cultivars were selected for each location and baseline soil samples collected before planting. Nitrogen fertilizer (0, 56, and 112 kg N ha) was applied each spring beginning the year after planting, and switchgrass was harvested once annually after senescence. Establishment, management, and harvest operations were completed using field-scale equipment. Switchgrass production ranged from 2 to 11.5 Mg ha across locations and years. Yields were lowest the first year after establishment. Switchgrass responded positively to N in 6 of 19 location/year combinations and there was one location/year combination (NY in Year 2) where a significant negative response was noted. Initial soil N levels were lowest in SD and VA (significant N response) and highest at the other three locations (no N response). Although N rate affected some measures of biomass quality (N and hemicellulose), location and year had greater overall effects on all quality parameters evaluated. These results demonstrate the importance of local field-scale research and of proper N management in order to reduce unnecessary expense and potential environmental impacts of switchgrass grown for bioenergy. [ABSTRACT FROM AUTHOR]

Switchgrass ( Panicum virgatum L.) is a C4 grass with high biomass yield potential and is now a model species for the Bioenergy Feedstock Development Program. Two distinct ecotypes (e.g., upland and lowland) and a range of plant morphotypes (e.g., leafy and stemmy) have been observed in switchgrass. The objective of this study was to determine the influence of ecotype and morphotype on biomass feedstock quality. Leaf and stem tissues of leafy and stemmy morphotypes from both lowland and upland ecotypes were analyzed for key feedstock traits. The leaf : stem ratio of leafy morphotype was more than 40% higher than the stemmy morphotype in both upland and lowland ecotypes. Therefore, the stemmy morphotype has significant advantages over leafy morphotype during harvesting, storage, transportation and finally the feedstock quality. Remarkable differences in feedstock quality and mineral composition were observed in switchgrass genotypes with distinct ecotypic origins and variable plant morphotypes. Lignin, hemicelluloses and cellulose concentrations were higher in stems than in the leaves, while ash content was notably high in leaves. A higher concentration of potassium was found in the stems compared to the leaves. In contrast, calcium was higher and magnesium was generally higher in the leaves compared to stems. The upland genotypes demonstrated considerably higher lignin (14.4%) compared with lowland genotypes (12.4%), while hemicellulose was higher in lowland compared with upland. The stemmy type demonstrated slightly higher lignin compared with leafy types ( P < 0.1). Differences between the ecotypes and morphotypes for key quality traits demonstrated the potential for improving feedstock composition of switchgrass through selection in breeding programs. [ABSTRACT FROM AUTHOR]

Biofuel crops may help achieve the goals of energy-efficient renewable ethanol production and greenhouse gas ( GHG) mitigation through carbon (C) storage. The objective of this study was to compare the aboveground biomass yields and soil organic C ( SOC) stocks under four crops (no-till corn, switchgrass, indiangrass, and willow) 7 years since establishment at three sites in Ohio to determine if high-yielding biofuel crops are also capable of high levels of C storage. Corn grain had the highest potential ethanol yields, with an average of more than 4100 L ha−1, and ethanol yields increased if both corn grain and stover were converted to biofuel, while willow had the lowest yields. The SOC concentration in soils under biofuels was generally unaffected by crop type; at one site, soil in the top 10 cm under willow contained nearly 13 Mg C ha−1 more SOC (or 29% more) than did soils under switchgrass or corn. Crop type affected SOC content of macroaggregates in the top 10 cm of soil, where macroaggregates in soil under corn had lower C, N and C : N ratios than those under perennial grasses or trees. Overall, the results suggest that no-till corn is capable of high ethanol yields and equivalent SOC stocks to 40 cm depth. Long-term monitoring and measurement of SOC stocks at depth are required to determine whether this trend remains. In addition, ecological, energy, and GHG assessments should be made to estimate the C footprint of each feedstock. [ABSTRACT FROM AUTHOR]

Pretreatment of lignocellulosic biomass for enhancing sugar yields has been studied extensively over the years. Conventional methods employed to preprocess biomass to make it conducive for enzymatic hydrolysis have been hampered by issues like poor energy efficiency and production of undesirable by-products. Ultrasonication, which involves the treatment of biomass through ultrasonic sound waves in a liquid medium without additional chemicals, is believed to have potential for biomass pretreatment. In this study the effects of ultrasonication on switchgrass, a potential feedstock for bioethanol production due to its high cellulosic content, were investigated. Results of compositional analysis and scanning electron microscopy conducted to visualize structural disintegration in sonicated samples were used to select pretreated samples for enzymatic hydrolysis at different enzyme loadings. Temperature controlled ultrasonication for 60 min at 100% amplitude in a stainless steel vessel, resulted in the highest carbohydrate conversions of 84.6% and 84.7% with Cellic® CTec2 and Alternafuel 200 L at 0.3 g enzyme protein g-1 dry biomass, respectively. However ultrasonication did not significantly impact composition of switchgrass and subsequent hydrolysis of untreated and treated samples was not significantly different. Based on the overall results, it is inferred that although ultrasonication alone did not provide enhanced sugar generation from switchgrass, its tendency to disrupt biomass structure could be utilized for preliminary size reduction steps and performance could be improved by further investigation of frequencies, amplitudes, enzyme loadings and process operation parameters. [ABSTRACT FROM AUTHOR]

To date, cellulosic ethanol production has not been commercialized in the United States. However, government mandates aimed at increasing second-generation biofuel production could spur exploratory development in the cellulosic ethanol industry. We conducted an in-depth analysis of the fuelshed surrounding a starch-based ethanol plant near York, Nebraska that has the potential for cellulosic ethanol production. To assess the feasibility of supplying adequate biomass for year-round cellulosic ethanol production from residual maize ( Zea mays) stover and bioenergy switchgrass ( Panicum virgatum) within a 40-km road network service area of the existing ethanol plant, we identified ∼14,000 ha of marginally productive cropland within the service area suitable for conversion from annual rowcrops to switchgrass and ∼132,000 ha of maize-enrolled cropland from which maize stover could be collected. Annual maize stover and switchgrass biomass supplies within the 40-km service area could range between 429,000 and 752,000 metric tons (mT). Approximately 140-250 million liters (l) of cellulosic ethanol could be produced, rivaling the current 208 million l annual starch-based ethanol production capacity of the plant. We conclude that sufficient quantities of biomass could be produced from maize stover and switchgrass near the plant to support year-round cellulosic ethanol production at current feedstock yields, sustainable removal rates and bioconversion efficiencies. Modifying existing starch-based ethanol plants in intensive agricultural fuelsheds could increase ethanol output, return marginally productive cropland to perennial vegetation, and remove maize stover from productive cropland to meet feedstock demand. [ABSTRACT FROM AUTHOR]

Switchgrass harvest and storage conditions increasingly affected a representative biochemical process and theoretical ethanol yield. The approach used a novel liquid ammonia fiber explosion (LAFEX) pretreatment technique implemented through engineered introduction of ammonia in liquid phase to biomass with controlled pressures, temperatures, and a mechanical liquid pump. The LAFEX pretreatment involved pressurizing an AFEX reactor with nitrogen prior to adding ammonia, and then nitrogen pressure was increased as the reactor temperature was increased to 100°C after the addition of ammonia. LAFEX pretreatment improved Alamo switchgrass xylan digestibility up to 63.3% compared to AFEX pretreatment that had published levels of xylan digestibility up to 38.3%, all using Accellerase enzyme for enzymatic hydrolysis. This improvement occurred at less water loading (0.8 vs. 2.0 g 1t20 per g dry switchgrass), less ammonia loading (1.0 vs. 1.6 and 2.0 g NH3 per g dry switchgrass), lower temperature (100°C vs. 160 °C and 150°C), and increased pretreatment time (120 vs. 30 and 25 min) for LAFEX vs. AFEX pretreatments, respectively. Additional potential for LAFEX pretreatment was noted based on published studies documenting enzymes that outperform the enzyme selected for this study. A wide range of switchgrass field harvest conditions, including one-cut versus two-cut strategies and harvest times ranging from June to January, indicated relatively small differences in fresh switchgrass cellulose and hemicellullose levels (64% to 68%) determined with wet chemistry, and associated trends in lignin increases (21.9% to 25. 7%) and ash decreases (5.3% to 2.2%) across samples obtained at harvest time, not including storage effects. Baseline theoretical ethanol yieM for freshly harvested samples ranged from 462 to 485 L per dry Mg. Field storage conditions included covered and uncovered bales and piles official-chopped switchgrass and ensiled field-chopped switchgrass. Field storage conditions affected cellulose and hemicellulose levels, as determined by wet chemistry, for theoretical ethanol yield (243 to 477 L per dr)/' Mg) to a greater degree than variation due to field harvest conditions. Implementation of enzymatic hydrolysis for 72 h with Accellerase 1000 introduced to LAFEX-pretreated samples represented a bioreftnery process for theoretical ethanol yield based on fresh harvest conditions (232 to 270 L per dry Mg) and revealed an exaggerated effect of storage conditions on theoretical ethanol yield (79 to 283 L per dry Mg). Essentially, switchgrass that got wet and stayed wet, compared to switchgrass that stayed dry or was allowed a drying cycle if exposed to precipitation during storage, reduced available cellulose and hemicelluloses (to -50%) and further reduced the available sugars from enzymatic hydrolysis (to -30%). It should be noted that no amount of improved pretreatment or enzymatic hydrolysis can overcome or recover the degraded sugars that occurred at the bale bottom under wet conditions. Overall results demonstrated the supply logistics challenge to deliver biomass feedstock with predictable, uniform conditions year-round to allow consistent biochemical conversion at commercial scale. Harvesting and storage conditions couM also affect biochemical processes associated with ethanol fermentation that were not investigated. [ABSTRACT FROM AUTHOR]

Switchgrass ( Panicum virgatum L.) is a potential biomass crop for native species-based biofuel systems in North America. A recently identified pest of switchgrass, the switchgrass moth, Blastobasis repartella (Dietz) (Lepidoptera: Coleophoridae), feeds in the basal above-ground internodes and below-ground in the proaxis and rhizomes, causing premature tiller and rhizome loss. Our goal was to determine genetic and temporal variation among six upland cultivars for frequency of tiller infestation by larvae of the switchgrass moth in mature stands in the northern Great Plains and if variation in biomass production was associated with variation in frequency of infestation. Data were collected in 2011 and 2012 for tiller density, biomass, frequency of infestation, number of leaves per healthy and infested tiller, and weights of healthy and infested tillers. Differences were found among cultivars for tiller density, biomass yield, and numbers of leaves per healthy and infested tillers. 'Summer', 'Sunburst', 'Pathfinder', and 'Cave-In-Rock' were the highest yielding cultivars. Mean frequency of infestation was different between 2011 (6.7 %) and 2012 (9.6 %). Infested tillers had one less collared leaf than healthy tillers. The weights of healthy tillers were ca. 3× those of infested tillers in both years, suggesting an impact on biomass accumulation and economic value. Levels of infestation were similar for all six cultivars, indicating no feeding preference by the switchgrass moth larva among genetically diverse cultivars of switchgrass. Regression of biomass yield on frequency of infestation showed negative linear relationships for 'Carthage' and 'Kentucky 1625'. [ABSTRACT FROM AUTHOR]

High yielding, native warm-season grasses could be used as renewable bioenergy feedstocks. The objectives of this study were to determine the effect of warm season grass monocultures and mixtures on yield and chemical characteristics of harvested biomass and to evaluate the effect of initial seeding mixture on botanical composition over time. Switchgrass ( Panicum virgatum L.), indiangrass [ Sorghastrum nutans (L.) Nash], and big bluestem ( Andropogon gerardii Vitman) were planted as monocultures and in all possible two- and three-way mixtures at three USA locations (Brookings and Pierre, SD and Morris, MN) during May 2002. Biomass at each location was harvested after a killing frost once annually from 2003 to 2005. Total biomass yield significantly increased with year at all locations. Switchgrass monocultures or mixtures containing switchgrass generally out-yielded big bluestem or indiangrass in monocultures or the binary mixture. Cellulose and hemicellulose concentrations were higher in 2004 and 2005 compared with 2003. Switchgrass or mixtures containing switchgrass tended to have less cellulose than either big bluestem or indiangrass. Results were more variable for total N, lignin, and ash. Switchgrass was the dominant component of all mixtures in which it was present while big bluestem was dominant when mixed with indiangrass. Indiangrass was maintained only in monocultures and declined over years when grown in mixtures at all locations. Our results indicated if biomass yield in the northern Great Plains is a primary objective, switchgrass should be a component of binary or tertiary mixtures that also contain big bluestem and/or indiangrass. [ABSTRACT FROM AUTHOR]

Abstract: To improve the cost-effectiveness of biomass-to-sugar conversion, sodium hydroxide (NaOH) pretreatment of switchgrass was carried out at 21°C using previously determined optimum conditions (2% NaOH (w/v), 6h), and the spent alkaline liquid (black liquor) was collected and used for pretreatment of corn stover, a feedstock exhibiting a higher susceptibility to NaOH attack, for improved enzymatic hydrolysis at a reduced cost. The results showed that, because of the high pH and the appreciable amount of carbohydrates in the black liquor, sugar production during enzymatic hydrolysis of corn stover pretreated with black liquor was comparable to that of biomass pretreated with 1% NaOH. After black liquor pretreatment at the best residence time (24h), the total reducing sugar, glucose, and xylose yields of corn stover reached 478.5, 287.7, and 145.3mg/g raw biomass, respectively, indicating the viability of this novel pretreatment technology. [Copyright &y& Elsevier]

The goal of this study was to evaluate performance of a 2 to 5 kg h-1 laboratory-scale fluidized bed biomass gasifier (FBBG) using switchgrass as a biomass feedstock. The main components of the FBBG system were a biomass feeding unit, a fluidized bed gasifier, an air supply unit with preheater, an air pressure regulator, two cyclone separators, an orifice plate, and a jet-type self-aerated producer gas burner. Silica sand was used as a bed material. Experiments were conducted to evaluate the effect of equivalence ratio (ER) on the reactor temperature profile, energy efficiencies, and producer gas yield and quality such as gas composition and particulate contents. An ER of 0.32 was found to be optimal with a producer gas higher heating value of 6.6 MJ Nm-3 and tar and particulates contents of 4.28 and 0.13 g Nm-3 respectively. The cold and hot gas efficiencies at the optimal condition were 71% and 75%, respectively, and these efficiencies decreased on either side of the optimal value of ER. Both gas yield and carbon conversion efficiency were found to be in positive correlation with ER, with maximum values of 2.5 Nm³ kg-1 biomass (d.b.) and 96%, respectively, at an ER of 0.45. [ABSTRACT FROM AUTHOR]

Abstract: Different types of feedstocks, including corn stover, wheat straw, soybean straw, switchgrass, and hardwood, were tested to evaluate the effectiveness of fungal pretreatment by Ceriporiopsis subvermispora. After 18-d pretreatment, corn stover, switchgrass, and hardwood were effectively delignified by the fungus through manganese peroxidase and laccase. Correspondingly, glucose yields during enzymatic hydrolysis reached 56.50%, 37.15%, and 24.21%, respectively, which were a 2 to 3-fold increase over those of the raw materials. A further 10–30% increase in glucose yields was observed when pretreatment time extended to 35d. In contrast, cellulose digestibility of wheat straw and soybean straw was not significantly improved by fungal pretreatment. When external carbon sources and enzyme inducers were added during fungal pretreatment of wheat straw and soybean straw, only glucose and malt extract addition improved cellulose digestibility of wheat straw. The cellulose digestibility of soybean straw was not improved. [Copyright &y& Elsevier]

Efforts are underway to meet the U.S. Department of Energy’s target of replacing 30% of fossil fuels used for transportation with biofuels by 2025. Extrusion appears to be one of the more viable continuous biomass pretreatment methods because several studies have shown significant improvements in sugar recovery from different feedstocks. Torque is an important factor which relates the power consumption during extrusion. The current study was undertaken to investigate the influence of extruder barrel temperature (45–225°C), screw speed (20–200 rpm), feedstock particle size (2–10 mm), and moisture content (10–50%) on torque and to propose a mathematical model to predict the torque requirement during extrusion pretreatment of switchgrass, prairie cord grass, corn stover, and big bluestem. Statistical analyses revealed that all independent variables studied had a significant effect on torque. A quadratic model was proposed to predict the torque requirement for different feedstocks, which had a high F and R 2 values along with low p value indicating the predictability of the model. Switchgrass, prairie cord grass, corn stover, and big bluestem required the torque ranges of 85–100, 27–42, 52–70, and 53–84 N m, respectively, for their optimised sugar recovery during pretreatment. Switchgrass required the highest torque amongst the feedstocks studied. [ABSTRACT FROM AUTHOR]

This study integrates a biophysical model with a county-specific economic analysis of breakeven prices of bioenergy crop production to assess the biophysical and economic potential of biofuel production in the Midwestern United States. The bioenergy crops considered in this study include a genotype of Miscanthus, Miscanthus× giganteus, and the Cave-in-Rock breed of switchgrass ( Panicum virgatum). The estimated average peak biomass yield for miscanthus in the Midwestern states ranges between 7 and 48 metric tons dry matter per hectare per year ( t DM ha−1 yr−1), while that for switchgrass is between 10 and 16 t DM ha−1 yr−1. With the exception of Minnesota and Wisconsin, where miscanthus yields are likely to be low due to cold soil temperatures, the yield of miscanthus is on average more than two times higher than yield of switchgrass. We find that the breakeven price, which includes the cost of producing the crop and the opportunity cost of land, of producing miscanthus ranges from $53 t−1 DM in Missouri to $153 t−1 DM in Minnesota in the low-cost scenario. Corresponding costs for switchgrass are $88 t−1 DM in Missouri to $144 t−1 DM in Minnesota. In the high-cost scenario, the lowest cost for miscanthus is $85 t−1 DM and for switchgrass is $118 t−1 DM, both in Missouri. These two scenarios differ in their assumptions about ease of establishing the perennial crops, nutrient requirements and harvesting costs and losses. The differences in the breakeven prices across states and across crops are mainly driven by bioenergy and row crop yields per hectare. Our results suggest that while high yields per unit of land of bioenergy crops are critical for the competitiveness of bioenergy feedstocks, the yields of the row crops they seek to displace are also an important consideration. Even high yielding crops, such as miscanthus, are likely to be economically attractive only in some locations in the Midwest given the high yields of corn and soybean in the region. [ABSTRACT FROM AUTHOR]

Abstract: Switchgrass, a perennial warm-season grass and potential energy crop, is usually harvested during the time between full maturity in the fall to the following spring. During this wide harvest window, the changes in fuel properties that could occur are important for making appropriate decisions with respect to the optimum harvest time for maximum fuel quality. A field plot study was carried out to investigate the quantitative fuel properties (proximate, ultimate and mineral analyses) of switchgrass over a harvest period from crop maturity in July through November. Harvest moisture decreased from July to November and moisture was uniformly distributed in the switchgrass plant at all times in the harvest period. There were significant differences in ash, volatiles, fixed carbon and nitrogen among months of harvest. Nitrogen, ash and fixed carbon contents decreased while oxygen and volatiles increased through the harvest period. Also, there were significant differences in oxides of silicon, calcium, potassium, phosphorus and sulfur among harvest times. The concentration of oxides of potassium and sulfur decreased at the end of the harvesting period. Fouling and slagging indices decreased as harvest was delayed but remained low throughout harvest. However, the decreases are small and might not dramatically impact fouling and slagging. Overall, the results appear to favor a later harvest for switchgrass used for direct combustion. This study will benefit feedstock producers as well as biomass feedstock facility operators by providing a better understanding of how the properties of switchgrass vary over a typical harvest period and their potential effect on boiler equipment. [Copyright &y& Elsevier]

Corn stover and switchgrass are two important biomass feedstocks being considered for commercial production of renewable fuels (ethanol), combined heat and power, chemicals, and bio-products in the U.S. These biomass feedstocks currently are collected as low-density bales involving high cost and energy for handling, transportation, storage, and use. Densification of biomass feedstocks into pellets/briquettes is a cost- and energy-effective strategy for a consistent, year-round supply of these biomass feedstocks for biobased and bioenergy industries. In this research, densification characteristics of corn stover and switchgrass were studied using a piston-cylinder densification apparatus to understand the densification and binding mechanisms, and to determine the optimum densification conditions for commercial production of pellets/briquettes from these biomass materials. The effects of densification process variables such as pressure (100 to 150 MPa), moisture content (8% to 20% wet basis), particle size (0.34 to 0.80 mm), and preheating temperature (75°C to 200°C) on the densification characteristics of corn stover and switchgrass were studied. At room temperature (about 25 ° C), corn stover briquettes (about 19.2 mm diameter) with relaxed densities (i.e., individual briquette densities measured one week after forming) of 745 to 1013 kg m-3 and switchgrass briquettes (about 19.4 mm diameter) with relaxed densities of 417 to 825 kg m-3 were produced. Densification at 25 °C resulted in briquette durability of 50% to 96% for corn stover and 0% for switchgrass. Preheating corn stover and switchgrass to 75 °C to 100 °C increased the density further and resulted in briquettes with maximum durability of 97% for corn stover, and 67% for switchgrass. The measured glass transition (i.e., softening) temperature of both corn stover and switchgrass averaged 75 °C. Densification conditions causing glass transition in the biomass was essential to fully activate the natural binding components such as lignin, protein, starch, and water-soluble carbohydrates in the biomass to help effective particle binding. The optimum densification condition to produce highly durable corn stover pellets/briquettes in commercial-scale systems is either conditioning the grind to a moisture content of 15% to 20% (wet basis) at room temperature (25°C) or preheating the grind to 75 °C at a moisture content of 10% to 15% (wet basis). The optimum densification condition for switchgrass is preheating the grind to >75 °C at a moisture content of 8% to 15% (wet basis). [ABSTRACT FROM AUTHOR]

Abstract: Switchgrass (Panicum virgatum L.) is a warm season perennial grass with great potential as an energy crop in the USA. It is widely adapted to many regions of the country, produces large amounts of biomass, serves as a useful forage grass, and provides ecosystem services that benefit soil and water quality and wildlife. Biological and thermochemical technologies are being developed to convert herbaceous biomass, including switchgrass, to energy. The objective of this research was to determine the effect of genotype and production environment on the concentration of minerals that affect the suitability of switchgrass for thermochemical conversion and to quantify the amount of potassium (K) and phosphorus (P) removed from the production system by harvest of the aboveground biomass, a measure of the sustainability of the practice. Straw dry biomass contained from 1.3 to 6.4kgMg−1 and from 6.2 to 15.8kgMg−1 of P and K, respectively. Variability in aluminum (Al), calcium (Ca), chloride (Cl), K, P, silicon (Si), and sulfur (S) concentrations across locations was relatively high, ranging from twofold (Al) to eightfold (Cl). Location had a strong impact on mineral concentrations among switchgrass genotypes evaluated in this study. Latitude of origin impacted the Cl and Si concentrations measured in plant tissues, but none of the other minerals analyzed in this study. Upland and lowland cytotypes explained some of the observed differences, but population×location interactions were the primary source of variability in the concentration of these minerals. [Copyright &y& Elsevier]

Abstract: The effects of five different biomass species and their chemical composition on the overall process efficiency and economic performance considering feedstock availability and feedstock costs to manufacture ethanol from lignocellulose were studied. First is a comparison of ethanol production and excess electricity generated between different biomass species. Results show that, at the same feedstock rate of 2000Mgday−1, aspen wood has larger ethanol production than switchgrass, hybrid poplar and corn stover, while the excess electricity generated is as follows in increasing order: aspen

Biofuels from crops are emerging as a Jekyll & Hyde – promoted by some as a means to offset fossil fuel emissions, denigrated by others as lacking sustainability and taking land from food crops. It is frequently asserted that plants convert only 0.1% of solar energy into biomass, therefore requiring unacceptable amounts of land for production of fuel feedstocks. The C4 perennial grass Miscanthus× giganteus has proved a promising biomass crop in Europe, while switchgrass ( Panicum virgatum) has been tested at several locations in N. America. Here, replicated side-by-side trials of these two crops were established for the first time along a latitudinal gradient in Illinois. Over 3 years of trials, Miscanthus× giganteus achieved average annual conversion efficiencies into harvestable biomass of 1.0% (30 t ha−1) and a maximum of 2.0% (61 t ha−1), with minimal agricultural inputs. The regionally adapted switchgrass variety Cave-in-Rock achieved somewhat lower yields, averaging 10 t ha−1. Given that there has been little attempt to improve the agronomy and genetics of these grasses compared with the major grain crops, these efficiencies are the minimum of what may be achieved. At this 1.0% efficiency, 12 million hectares, or 9.3% of current US cropland, would be sufficient to provide 133 × 109 L of ethanol, enough to offset one-fifth of the current US gasoline use. In contrast, maize grain from the same area of land would only provide 49 × 109 L, while requiring much higher nitrogen and fossil energy inputs in its cultivation. [ABSTRACT FROM AUTHOR]

Upgrading biomass waste streams can improve economics in wood industries by adding value to the process. This work considers use of a hydrothermal carbonization (HTC) process for the residual feedstock after lignin and hemicelluloses extraction. Batch experiments were performed at 200–240 °C temperatures and three hours residence time with an 8:1 biomass to water ratio for two feedstocks: Raw spruce and spruce after lignin extraction. The proximate analysis and heating value showed similar results for both feedstocks, indicating that the thermochemical conversion is not impacted by the removal of lignin and hemicelluloses; the pretreatment processing slightly increases the heating value of the treated feedstock, but the HTC conversion process produces a consistent upgrading trend for both the treated and untreated feedstocks. The energy yield was 9.7 percentage points higher for the treated wood on average across the range temperatures due to the higher mass yield in the treated experiments. The energy densification ratio and the mass yield were strongly correlated with reaction temperature, while the energy yield was not. Lignocellulosic composition of the solid HTC product is mainly affected by HTC treatment, the effect of lignin extraction is negligible. [ABSTRACT FROM AUTHOR]

Switchgrass (Panicum virgatum L.) is a C4, warm season, perennial native grass that has been strongly recommended as an ideal biofuel feedstock. Accurate forecasting of switchgrass yield across a geographically diverse region and under future climate conditions is essential for determining realistic future ethanol production from switchgrass. This study compiled a switchgrass database through reviewing the existing literature from field trials across the U.S. Using observed switchgrass data, a process-based model (ALMANAC) was developed. The ALMANAC simulation results showed that crop management had more effect on yield than location. The ALMANAC model consists of functional relationships that provide a better understanding of interactions among plant physiological processes and environmental factors (water, soil, climate, and nutrients) giving realistic predictions in different climate conditions. This model was used to quantify the impacts of climate change on switchgrass yields. Simulated lowland switchgrass would have more yield increases between Illinois and Ohio in future (2021–2050) under both Representative Concentration Pathway (RCP) 4.5 and 8.5 pathways with low N fertilizer inputs than high N fertilizer inputs. There was no significant effect of climate variability on upland simulated yields, which means that N fertilization is a key factor in controlling upland switchgrass yields under future climate conditions. [ABSTRACT FROM AUTHOR]