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The push for renewable energy sources has local government agencies striving to optimize their limited resources. Various energy sources are often explored depending on the region – for example, wind, solar, geothermal, and bioenergy. The Piedmont region of the USA has the potential to be a significant player in the production of biomass to supply a biorefinery. However, before local agencies and private biorefineries can invest in such an endeavor, the potential feedstock supply must be quantified. The goal of this study was to perform a land‐use assessment for the 166 counties spanning five states (Virginia, North Carolina, South Carolina, Georgia, and Alabama) that make up the bulk of the Piedmont region. For each county, the potential for producing and supplying herbaceous feedstock (i.e., switchgrass) was quantified based on 2017 land use. Only 48% of the counties had the potential to supply a biorefinery larger than 0.5 round bales per min (bpm) (97 000 Mg year–1). To supply a more reasonably sized biorefinery, the Piedmont counties were organized into 34 multi‐county zones. For these zones, the potential switchgrass production to supply a biorefinery ranged from 50 000 Mg year–1 to 360 000 Mg year–1. The total feedstock production for the region was 6 470 000 Mg year–1, equal to a potential production of about 3.3% of the current US consumption of ethanol for blending with gasoline. The development of a bioenergy industry in the Piedmont will require local leadership and initiative; however, this study provides the first step in envisioning the potential of such an industry. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

The production of dedicated energy crops on marginally productive cropland is projected to play an important role in reaching the US Billion Ton goal. This study aimed to evaluate warm‐season grasses for biomass production potential under different harvest timings (summer [H1], after killing frost [H2], or alternating between two [H3]) and nitrogen (N) fertilizer rates (0, 56, and 112 kg N/ha) on a wet marginal land across multiple production years. Six feedstocks were evaluated including Miscanthus x giganteus, two switchgrass cultivars (Panicum virgatum L.), prairie cordgrass (Spartina pectinata Link), and two polycultures including a mixture of big bluestem (Andropogon gerardii Vitman), indiangrass (Sorghastrum nutans), and sideoats grama (Bouteloua curtipendula [Michx.] Torr.), and a mixture of big bluestem and prairie cordgrass. Across four production years, harvest timing and feedstock type played an important role in biomass production. Miscanthus x giganteus produced the greatest biomass (18.7 Mg/ha), followed by the switchgrass cultivar "Liberty" (14.7 Mg/ha). Harvest in H1 tended to increase yield irrespective of feedstock; the exception being M. x giganteus that had significantly lower biomass when harvested in H1 when compared to H2 and H3. The advantage H1 harvest had over H2 for all feedstocks declined over time, suggesting H2 or H3 would provide greater and more sustainable biomass production for the observed feedstocks. The N application rate played an important role mainly for M. x giganteus where 112 kg N/ha yielded more biomass than no N. Other feedstocks occasionally showed a slight, but statistically insignificant increase in biomass yield with increasing N rate. This study showed the potential of producing feedstocks for bioenergy on wet marginal land; however, more research on tissue and soil nutrient dynamics under different N rates and harvest regimes will be important in understanding stand longevity for feedstocks grown under these conditions. [ABSTRACT FROM AUTHOR]

Cellulosic biofuels are an important source of renewable biomass within the alternative energy portfolio. Switchgrass (Panicum virgatum L.), a perennial C4 grass native to North America, is widely studied as a biofuel feedstock for its consistently high yields and minimal input requirements. The influences of precipitation amount and temporal variability on the fertilizer response of switchgrass productivity are not fully understood. Moreover, global climate models predict changes in rainfall patterns towards lower and increasingly variable soil water availability in several productive areas worldwide, which may impact net primary production of biofuel crops. We conducted a meta-analysis of aboveground net primary production of switchgrass from 48 publications encompassing 82 different locations, 11 soil types, 52 switchgrass cultivars, fertilizer inputs between 0 to 896 kg N ha−1 year−1, and 1 to 6 years of annual productivity measures repeated on the same stand. Productivity of the lowland ecotype doubled with N rates > 131 kg N ha−1 year−1, but upland ecotype productivity increased only by 50%. Results showed an optimum N rate of 30 to 60 kg N ha−1 year−1 for both ecotypes, after which biomass gain per unit of N added decreased. Growing season precipitation (GSPPT) and inter-annual precipitation variability (inter-PPTvar) affected both ecotypes similarly. Long-term mean annual precipitation (MAP) differentially affected lowland and upland productivity, depending on the N level. Productivity responses to MAP and GSPPT were similar for both upland and lowland ecotypes at none or low N rates. When N increased beyond 60 kg N ha−1 year−1, lowland cultivars had a greater growth response to MAP than uplands. Productivity increased with increasing GSPPT and MAP and had a positive linear response to MAP ranging from 600 to 1200 mm year−1. One third of the variability in switchgrass production was accounted for by inter-PPTvar. After accounting for MAP, sites with higher inter-PPTvar had lower switchgrass productivity than sites with lower inter-PPTvar. Increased inter-annual variation in precipitation reduced production of both ecotypes. Predicted changes in the amount and timing of precipitation thus likely will exert greater influence on production of upland than lowland ecotypes of switchgrass. [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]

Switchgrass (Panicum virgatum L.) and giant miscanthus (Miscanthus x giganteus Greef & Deuter ex Hodkinson & Renvoize) are productive on marginal lands in the eastern USA, but their productivity and composition have not been compared on mine lands. Our objectives were to compare biomass production, composition, and theoretical ethanol yield (TEY) and production (TEP) of these grasses on a reclaimed mined site. Following 25 years of herbaceous cover, vegetation was killed and plots of switchgrass cultivars Kanlow and BoMaster and miscanthus lines Illinois and MBX-002 were planted in five replications. Annual switchgrass and miscanthus yields averaged 5.8 and 8.9 Mg dry matter ha−1, respectively, during 2011 to 2015. Cell wall carbohydrate composition was analyzed via near-infrared reflectance spectroscopy with models based on switchgrass or mixed herbaceous samples including switchgrass and miscanthus. Concentrations were higher for glucan and lower for xylan in miscanthus than in switchgrass but TEY did not differ (453 and 450 L Mg−1, respectively). In response to biomass production, total ethanol production was greater for miscanthus than for switchgrass (5594 vs 3699 L ha−1), did not differ between Kanlow and BoMaster switchgrass (3880 and 3517 L ha−1, respectively), and was higher for MBX-002 than for Illinois miscanthus (6496 vs 4692 L ha−1). Relative to the mixed feedstocks model, the switchgrass model slightly underpredicted glucan and slightly overpredicted xylan concentrations. Estimated TEY was slightly lower from the switchgrass model but both models distinguished genotype, year, and interaction effects similarly. Biomass productivity and TEP were similar to those from agricultural sites with marginal soils. [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]

In the North-Central USA, switchgrass to be used as a biomass feedstock typically will be harvested in the autumn. The accumulated area harvested over the harvest season (defined here as the harvest progression) will influence the size of the machinery fleet and seasonal labor required to complete the majority of the harvest before the first lasting snow. A harvest progression model was developed that uses drying rate, mower and baler productivity, and weather conditions as major inputs. Ten years of weather data (2005-2014) from Wisconsin, Iowa, and Nebraska (WI, IA, NE) were used. Harvest progression was modeled for four harvest systems involving conventional and intensive conditioning both swathed and tedded (CC, IC, CCT, and ICT, respectively) and two dates at which harvest began (1 September and after a killing frost). To reduce risk of exposing crop to prolonged periods of inclement weather, mowers were idled when more than 80 ha were cut but not yet baled. For all sites, the harvest start date and the mower idled constraint had greater impact on harvest progression than the type of harvest system. Harvest progression was greatest when mowing started on 1 September and continued whenever weather permitted (i.e., no mower idled constraint). Compared to the harvest system used today (CC), using the IC system resulted in more area harvested with less crop exposed to rain after cutting and considerably less area left to be baled in the spring. Starting harvest on 1 September, using intensive conditioning, and not idling the mowers might be considered the system that best balances the desire for rapid harvest progression, small equipment fleet size, low-capital expenditures, and maximum labor utilization. [ABSTRACT FROM AUTHOR]

This study assesses the supply of switchgrass and miscanthus, in Ontario, Canada, under different biomass prices and supply chain structures, using an integrated economic, biophysical and GIS model, to assess bioenergy policy. In a local, domestic supply chain, 4 million tonnes of baled biomass production per year becomes attractive for transport to the Nanticoke Generation Station at $69/t. For a larger scale export supply chain to Rotterdam in the form of biomass pellets aggregated on the farm, 20 million tonnes of production becomes attractive at approximately $198/t. For an export supply chain with aggregation at the major ports of Ontario, 20 million tonnes of baled biomass product is attractive for shipping to ports, with pellets subsequently transported to Rotterdam, at around $137/t. Higher bale transportation costs mean that agricultural lands closer to ports, but with lower yields, are preferred compared to the on-farm aggregation scenario. Given government incentives to ease the transition between annual and perennial crops and an actual realized demand from the Nanticoke Generation Station for biomass, this supply chain scenario is plausible. However, export scenarios are not attractive due to infrastructure constraints from current pellet processing capacity, and volatile international energy and commodity markets. [ABSTRACT FROM AUTHOR]

The perennial grass species that are being developed as biomass feedstock crops harbor extensive genotypic diversity, but the effects of this diversity on biomass production are not well understood. We investigated the effects of genotypic diversity in switchgrass ( Panicum virgatum) and big bluestem ( Andropogon gerardii) on perennial biomass cropping systems in two experiments conducted over 2008-2014 at a 5.4-ha fertile field site in northeastern Illinois, USA. We varied levels of switchgrass and big bluestem genotypic diversity using various local and nonlocal cultivars - under low or high species diversity, with or without nitrogen inputs - and quantified establishment, biomass yield, and biomass composition. In one experiment ('agronomic trial'), we compared three switchgrass cultivars in monoculture to a switchgrass cultivar mixture and three different species mixtures, with or without N fertilization. In another experiment ('diversity gradient'), we varied diversity levels in switchgrass and big bluestem (1, 2, 4, or 6 cultivars per plot), with one or two species per plot. In both experiments, cultivar mixtures produced yields equivalent to or greater than the best cultivars. In the agronomic trial, the three switchgrass mixture showed the highest production overall, though not significantly different than best cultivar monoculture. In the diversity gradient, genotypic mixtures had one-third higher biomass production than the average monoculture, and none of the monocultures were significantly higher yielding than the average mixture. Year-to-year variation in yields was lowest in the three-cultivar switchgrass mixtures and Cave-In-Rock (the southern Illinois cultivar) and also reduced in the mixture of switchgrass and big bluestem relative to the species monocultures. The effects of genotypic diversity on biomass composition were modest relative to the differences among species and genotypes. Our findings suggest that local genotypes can be included in biomass cropping systems without compromising yields and that genotypic mixtures could help provide high, stable yields of high-quality biomass feedstocks. [ABSTRACT FROM AUTHOR]

This study examined the effects of mild sodium carbonate (Na 2 CO 3 ) pretreatment on enzymatic hydrolysis of different feedstocks (i.e., corn stover, Miscanthus , and switchgrass). The results showed that sodium carbonate pretreatment markedly enhanced the sugar yields of the tested biomass feedstocks. The pretreated corn stover, Miscanthus , and switchgrass gave the glucose yields of 95.1%, 62.3%, and 81.3%, respectively, after enzymatic hydrolysis. The above glucose yields of pretreated feedstocks were 2–4 times that of untreated ones. The pretreatment also enhanced the xylose yields, 4 times for corn stover and 20 times for both Miscanthus and switchgrass. Sodium carbonate pretreatment removed 40–59% lignin from the tested feedstocks while preserving most of cellulose (<5% cellulose loss). Corn stover appeared to be least resistant to breakdown by Na 2 CO 3 and enzymatic hydrolysis. Our study indicated that mild sodium carbonate pretreatment was effective for reducing biomass recalcitrance and subsequently improving the digestibility of lignocellulosic biomass. [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]

Switchgrass ( Panicum virgatum L.) is a perennial warm-season grass identified as a model species for bioenergy feedstock production. Established switchgrass stands are very resilient to the environmental fluctuations; however, seed dormancy and weak seedling vigor make establishment difficult. Breaking seed dormancy of switchgrass is a first step to reduce risk of establishment failure and the costs associated with reseeding. Many studies have reported a myriad of methods to break seed dormancy of switchgrass, including chemical, mechanical, thermal, and hormonal seed treatments. Length of seed storage, storage conditions (e.g., temperature and humidity), and prior soil conditions (e.g., soil salinity and fertilizer rates) affect switchgrass seed dormancy. Strong interactions exist among germination, seedling emergence, and soil conditions; therefore, treated seeds tested in soil media will generate more accurate results following dormancy breaking techniques. This paper reviews the current methods used to break switchgrass seed dormancy. [ABSTRACT FROM AUTHOR]

Switchgrass is a promising biofuel feedstock due to its high biomass production and low agronomic input requirements. Because the bulk of switchgrass biomass used for biofuel production is lignocellulosic secondary walls, studies on secondary wall biosynthesis and its transcriptional regulation are imperative for designing strategies for genetic improvement of biomass production in switchgrass. Here, we report the identification and functional characterization of a group of switchgrass transcription factors, including several NACs (PvSWNs) and a MYB (PvMYB46A), for their involvement in regulating secondary wall biosynthesis. PvSWNs and PvMYB46A were found to be highly expressed in stems and their expression was closely associated with sclerenchyma cells. Overexpression of PvSWNs and PvMYB46A in Arabidopsis was shown to result in activation of the biosynthetic genes for cellulose, xylan and lignin and ectopic deposition of secondary walls in normally parenchymatous cells. Transactivation and complementation studies demonstrated that PvSWNs were able to activate the SNBE-driven GUS reporter gene and effectively rescue the secondary wall defects in the Arabidopsis snd1 nst1 double mutant, indicating that they are functional orthologs of Arabidopsis SWNs. Furthermore, we showed that PvMYB46A could activate the SMRE-driven GUS reporter gene and complement the Arabidopsis myb46 myb83 double mutant, suggesting that it is a functional ortholog of Arabidopsis MYB46/MYB83. Together, these results indicate that PvSWNs and PvMYB46A are transcriptional switches involved in regulating secondary wall biosynthesis, which provides molecular tools for genetic manipulation of biomass production in switchgrass. [ABSTRACT FROM AUTHOR]

Lignocellulosic biorefineries that plan to use switchgrass ( Panicum virgatum L.) biomass exclusively will encounter both temporal (across years) and spatial (across locations within a given year) variability in feedstock production. Long term land leases could be employed to facilitate feedstock availability for the expected life of the biorefinery. If the quantity of land leased is based on average yields, in some years more biomass will be produced than can be processed. In other years feedstock production on the leased land may be insufficient to prevent biorefinery downtime. An optimal strategy for identifying which land to lease and seed to switchgrass, while considering yield variability and the opportunity cost of biorefinery downtime, is the focus of the research. The objective is to determine for a given biorefinery location the least-cost quantity, quality, and location of land to lease for alternative estimates of biorefinery downtime cost due to variable switchgrass yields. Fifty years of weather data are used to simulate switchgrass yield distributions for a case study region. An innovative mathematical programming model is developed and used to reveal the cost-efficient D (Downtime Cost) L (Land to Lease) frontier for a 2 Gg d −1 biomass capacity biorefinery. If interyear storage is not permitted, 60,492 ha would be required to insure that the biorefinery run at full capacity every year given the estimated yield distributions. However, for some circumstances, it would be optimal to produce switchgrass on only 49,464 ha and idle the biorefinery for some days in low biomass production years. [ABSTRACT FROM AUTHOR]

Mobile pyrolysis units have the potential to greatly simplify feedstock logistics by moving pyrolysis equipment to the feedstock production fields to produce bio-oil. The concept is to use mobile pyrolysis units to convert low-density biomass to high-density bio-oil to minimize feedstock transportation costs. A recently published GIS program was used to assess feedstock availability for mobile pyrolysis units in the North Central (NC) region using GIS databases. The feed- stocks chosen for this study were corn stover, energy sorghum, and switchgrass. The GIS program identified optimum locations for mobile pyrolysis stations based on feedstock availability and calculated the routes and distances between the optimum pyrolysis stations. The GIS program utilized a harvest grid concept with the mobile pyrolysis unit located in the center of a square grid cell. It was assumed that the mobile pyrolysis units would move on discrete time steps of 1, 2, 4, 6, 8, 10, and 12 months (stationary). The harvest grid sizes ranged from 2.4 to 9.6 km for corn stover, from 5.0 to 23.0 km for energy sorghum, and from 3.3 to 12.0 km for switchgrass, depending on move times. In the NC region, the distances required to move the mobile pyrolysis unit from one location to the next varied from 2.1 to 138.7 km for corn stover, from 4.4 to 81.0 km for energy sorghum, and from 3.0 to 60.7 km for switchgrass. The distances required to transport bio-oil to the closest oil refineries ranged from 81.0 to 195.0 km for corn stover, from 365.0 to 522.0 km for energy sorghum, and from 192 to 265 km for switchgrass. Using these optimized feedstock logistics, a total of 14,825,993 barrels (2,357,144,597 L) of bio-oil could be produced by 853 mobile pyrolysis units using 25% of the corn stover in Illinois. In Nebraska, 469,287 barrels (74,610,673 L) of bio-oil could be produced by 27 mobile units using energy sorghum, and 903,812 barrels (143,694,630 L) of bio-oil could be produced by 52 mobile units using switchgrass. [ABSTRACT FROM AUTHOR]

As a native, low-input crop with high biomass production, switchgrass ( Panicum virgatum) has become a favorable feedstock for the production of cellulosic biofuels in the United States. Many efforts are being made to improve the production of cellulosic biofuels from switchgrass. Protocols regarding analysis of switchgrass biomass have been established; however, the developmental stage of the materials being analyzed has varied depending on researchers' discretion, and no standardized harvesting procedure has been defined. Developmental stages have a large impact on the results of biochemical analyses. We propose a standardized procedure for switchgrass sample collection for cell wall and biomass analyses by describing various developmental stages of switchgrass, defining the R1 stage as the stage at which tillers should be collected, and providing a detailed description of how and what material should be analyzed. Such a standardized procedure will help to maintain consistency in switchgrass evaluation methods, enable comparisons of data obtained from different approaches and studies, and facilitate efforts towards improving switchgrass as a bioenergy crop. [ABSTRACT FROM AUTHOR]

Abstract: Switchgrass was used as a lignocellulosic feedstock for second generation ethanol production, after pretreatment using sulfuric acid-catalyzed modified clean fractionation based on NREL’s (National Renewable Energy Laboratory) original procedure. Optimization of temperature, catalyst concentration and solvent composition was performed using Response Surface Methodology, and 59.03±7.01% lignin recovery, 84.85±1.34% glucose, and 44.11±3.44% aqueous fraction xylose yields were obtained at 140.00°C, 0.46% w/w catalyst concentration, 36.71% w/w ethyl acetate concentration, and 25.00% w/w ethanol concentration. The cellulose fraction did not inhibit the fermentation performance of Saccharomyces cerevisiae and resulted in an ethanol yield of 89.60±2.1%. [Copyright &y& Elsevier]

Abstract: To evaluate the potential of gamagrass as a feedstock for biofuels, seven gamagrass varieties were analyzed for their chemical composition and subjected to pretreatment at 121°C using 1% NaOH/H2SO4 (w/w) for 60min and enzymatic hydrolysis for fermentable sugar production. Based on total sugar yield, the varieties Eagle Point Devil Corn and Sun Devil were selected for NaOH and H2SO4 pretreatment, respectively. The investigation on pretreatment conditions showed that, the conditions applied in gamagrass variety screening (121°C, 1% NaOH/H2SO4, 60min) were sufficient to maximize sugar production, such that the total sugar yield of Eagle Point Devil Corn reached 479.6mgg−1 after NaOH pretreatment and that of Sun Devil reached 456.5mgg−1 raw biomass after H2SO4 pretreatment. Compared with other potential energy crops including switchgrass and Bermuda grass, gamagrass gave a higher sugar yield after NaOH pretreatment and a comparable sugar yield after H2SO4 pretreatment. [Copyright &y& Elsevier]

A two-year nutrient omission trial was conducted on semiarid wasteland to determine the effects of nitrogen (N), phosphorus (P), and potassium (K) on the chemical composition and theoretical ethanol yield (TEY) of switchgrass (Panicum virgatum L.). The fertilizer treatments were the following: NPK, PK, NK, NP, and no nutrient inputs (CK). Results indicated that the crude protein (CP) content and protein yield of switchgrass aboveground biomass decreased significantly in the PK treatment (N omission) and the CK, compared with the NPK treatment. The omission of N, P, or K did not significantly affect the other feed and energy quality indicators. When averaged across the two years, the neutral- and acid-detergent fiber contents were lower in the NPK and NP treatments, but the CP, dry matter digestibility, dry matter intake, total digestible nutrients, net energy for lactation, and relative feed value were higher, indicating that the suitable application with combination of N and P was helpful to improve the forage quality of switchgrass. In PK and CK treatments, the contents of soluble sugar, cellulose, and hemicellulose were higher but that of ash was lower than that in other three treatments, indicating that no N application meant better quality of switchgrass aboveground biomass for bioethanol production. The TEY at NPK was 2532 L ha−1 in 2015 and 2797 L ha−1 in 2016; in particular, the TEY decreased significantly by 15.1% in PK, 14.7% in NK, 10.5% in NP, and 29.9% in CK in 2016. To conclude, N was the most limiting factor in switchgrass productivity and the combined N, P, and K nutrient supply management strategy is recommended based on the consideration of quality and quantity of switchgrass as forage and bioenergy feedstock on semiarid marginal land. [ABSTRACT FROM AUTHOR]

A current concern is the increase in greenhouse gas emissions, mainly CO2, with anthropogenic sources being the main contributors. Microalgae have greater capacity than terrestrial plants to capture CO2, with this being an attraction for using them as capture systems. This study aims at the techno-economic evaluation of microalgae biomass production, while only considering technologies with industrial scaling potential. Energy consumption and operating costs are considered as parameters for the evaluation. In addition, the capture of CO2 from a thermoelectric plant is analyzed, as a carbon source for the cultivation of microalgae. 24 scenarios were evaluated while using process simulation tools (SuperPro Designer), being generated by the combination of cultivations in raceway pond, primary harvest with three types of flocculants, secondary harvest with centrifugation and three filtering technologies, and finally the drying evaluated with Spray and Drum Dryer. Low biomass productivity, 12.7 g/m2/day, was considered, achieving a capture of 102.13 tons of CO2/year in 1 ha for the cultivation area. The scenarios that included centrifugation and vacuum filtration are the ones with the highest energy consumption. The operating costs range from US $ 4.75–6.55/kg of dry biomass. The choice of the best scenario depends on the final use of biomass. [ABSTRACT FROM AUTHOR]