Potential Ethanol Yield Research Articles

Which crop has the highest bioethanol yield in the United States?

Annual U.S. production of bioethanol, primarily produced from corn starch in the U.S. Midwest, rose to 57 billion liters in 2021, which fulfilled the required conventional biofuel target set forth by the Energy Independence and Security Act (EISA) of 2007. At the same time, the U.S. fell short of the cellulosic or advanced biofuel target of 79 billion liters. The growth of bioenergy grasses (e.g., Miscanthus and switchgrass) across the Central and Eastern U.S. has the potential to feed enhanced cellulosic bioethanol production and, if successful, increase renewable fuel volumes. However, water consumption and climate change and its extremes are critical concerns in corn and bioenergy grass productivity. These concerns are compounded by the demands on potentially productive land areas and water devoted to producing biofuels. This is a fundamental Food-Energy-Water System (FEWS) nexus challenge. We apply a computational framework to estimate potential bioenergy yield and conversion to bioethanol yield across the U.S., based on crop field studies and conversion technology analysis for three crops—corn, Miscanthus, and two cultivars of switchgrass (Cave-in-Rock and Alamo). The current study identifies regions where each crop has its highest yield across the Center and Eastern U.S. While growing bioenergy grasses requires more water than corn, one advantage they have as a source of bioethanol is that they control nitrogen leaching relative to corn. Bioenergy grasses also maintain steadily high productivity under extreme climate conditions, such as drought and heatwaves in the year 2012 over the U.S. Midwest, because the perennial growing season and the deeper and denser roots can ameliorate the soil water stress. While the potential ethanol yield could be enhanced using energy grasses, their practical success in becoming a potential source of ethanol yield remains limited by socio-economic and operational constraints and concerns regarding competition with food production.

A sustainable agricultural strategy integrating Cd-contaminated soils remediation and bioethanol production using sorghum cultivars

Cadmium (Cd) contaminant in soil can pollute crops and poison consumers higher in the food chain. Sorghum (Sorghum bicolor (L.) Moench) is a promising bioenergy crop that can absorb and accumulate Cd from soil while generate renewable biomass resources for bioethanol or other valuable products, and limit waste production by rational utilization of all components. In this study, a sustainable agricultural strategy was presented and six sorghum cultivars grown under field conditions for the phytoremediation of Cd-contaminated agricultural soil were investigated with the goal of comparing their ability to accumulate Cd and their theoretical bioethanol yields (Cd concentration in the soil was 0.25 and 0.96 ppm). Striking differences were found in the Cd accumulation of these sorghum cultivars, and the result indicated that the Cd accumulation in stalks increased with maturity. The total absorbability of Cd ranged from 19.6 to 148 g/ha, and N6G60 sorghum showed the highest Cd accumulation with a concentration of 9.16 ppm in the stalk on a dry basis. The theoretical yield of bioethanol ranged from 5510 to 7510 L/ha. The overall performance of N6G60 and 15016 sorghums surpassed that of other sorghum cultivars because of their stronger capacities for Cd translocation and higher theoretical yields of bioethanol. Considering the experimental results, as well as the potential ethanol yield and growing situations of sorghums, 15016 sorghum was considered the cultivar showing the most promise for future applications.

Ethanol Production Potential of Sweet Sorghum in North and Central Ukraine

Background: Sweet sorghum (Sorghum saccharatum (L.) Moench) is a unique crop with great potential to serve both the food and energy industries. It is due to the possibility of (bio)ethanol production both from the juice and biomass of this crop. The sorghum stems juice contains sugar in the levels similar to that of sugarcane. Besides, low cultivation requirements for the sweet sorghum make this crop even more attractive for sugar and ethanol production. In terms of technology, sweet sorghum is seen as a transitional feedstock for the first to the second generation bioethanol production. However, effective technological development of the plant cultivation and processing in the Northern and Central Ukraine is restrained by the lack of a collection of sweet sorghum genotypes and adapted varieties for its large-scale cultivation. Additionally, no evaluations of potential (bio)ethanol productivity have been performed for this region, which is important for efficient implementation of novel biofuel-producing technologies and for successful development of a green economy. Objective: This research was aimed to create a pool of sweet sorghum genotypes with the involvement of worldwide germplasm, analyze their morphology and breed high-yielding plant lines for the efficient production of liquid biofuels for second-generation bioenergy. Based on that, we also aimed to explore the prospects regarding the efficiency of sweet sorghum cultivation for (bio)ethanol production in the Northern and Central Ukraine. Methods and Materials: A valuable gene pool of S. saccharatum (L.) Moench (41 samples) was created; in particular, high-performance genotypes were created for cultivation under the soil-climatic conditions of Ukraine. The bio-morphological features and the yield potential of the plants were determined and the biochemical composition of the phyto-raw materials was determined in different periods of vegetation, in particular, during the technical ripeness of the above-ground mass of plants. The more productive forms and varieties of sugar sorghum in terms of yield, dry matter content, sugar, and energy value of biomass during flowering and waxy ripeness are highlighted. The technological properties of plant biomass for the production of alternative liquid fuels (in particular, bioethanol) have been analyzed. Importantly, optimal cultivation conditions have been elaborated for the newly created sweet sorghum genotypes, and their productivity has also been evaluated. Moreover, for the first time, a detailed study on potential ethanol yield has been conducted. Results: Sweet sorghum has considerable potential in Ukraine as a new sugar-producing energy crop. The germplasm collection of this crop has been created (41 accessions), including introduced and acclimated genotypes and newly bred lines and varieties. The biological performance of sorghum in Ukraine and plant morphology have been analyzed. The most promising genotypes were used for breeding of new high-productive sweet sorghum varieties. The potential (bio)ethanol yield for different sugar feedstocks (juice, grain bagasse) can reach up to 11423 L/ha in total from juice, grain and bagasse. Conclusion: The estimated values of ethanol productivity are comparable to the results of other similar investigations. In conclusion, a high performance of sweet sorghum in Ukraine can be suggested.

Greener gas? Impact of biosolids on carbon intensity of switchgrass ethanol.

Synthetic fertilizers make up a significant fraction of the energy required to grow switchgrass (Panicum virgatum L.) for ethanol production. A field study compared biosolids and synthetic fertilizers on biomass yield, ethanol production, and nitrous oxide (N2 O) emissions of switchgrass to determine if using an alternative source of nutrient would lower the energy density of the fuel. Minimal N2 O emissions were observed the first year of the study (0.99±1.5g N2 O ha-1 d-1 for biosolids), with no difference between treatments. Biosolids were added in excess of agronomic rates, and gas samples were collected immediately after irrigation for the subsequent years to examine maximum N2 O emissions. Mean Year 2 emissions increased for fertilizers to 1.8±8g N2 O ha-1 d-1 (n=131) and to 3.73±10.2g N2 O ha-1 d-1 (n=130) for biosolids-amended soils. Emissions in Year 3 were similar to Year 2. Yield was similar and ranged from 3.7±5 to 11±1.1 and from 5.0 ± 0.2 to 13.4 ± 1.7 Mg ha-1 for biosolids and fertilizer, respectively. The potential ethanol yield was 365 ± 28 L Mg-1 and 374 ± 34 L Mg-1 for the biosolids- and fertilizer-grown grass, respectively. Greenhouse gas emissions associated with fertilizer production were considered for N, P, and K and totaled 1,653kg carbon dioxide equivalent (CO2 e) ha-1 . The equivalent credits for substitution of biosolids (18 Mg ha-1 ) were -2,492kg CO2 e ha-1 . Nitrous oxide emissions were calculated based on 1% of total N applied for agronomic applications and were 8,600 and 3,500g N2 O ha-1 for the biosolids and fertilizer treatments, respectively. Total carbon costs associated with fertilization were 2,700kg CO2 e ha-1 for fertilizer and 60kg CO2 e ha-1 for biosolids. Using measured N2 O data would have resulted in lower emissions for both treatments.

Biofuel and valuable products recovery from Napier grass pre-processing: Process design and economic analysis

Utilisation of lignocellulosic materials as alternative sources of clean energy is characterised with high energy consumption during pre-processing. This study presents a novel approach for processing of high moisture content biomass through a steady state process design and economic analysis. The process flow diagram was developed by considering two process scenarios of Napier grass pre-processing down to the final bio-products with and without solid residue drying. A Napier grass stem processing plant (100 kg/h wet basis) with on-site facilities was modelled using ASPEN PLUS® V10. A model-based estimation approach, Aspen Process Economic Analyser (APEA) was used to generate both capital and operating costs estimates, and other investment analysis following first quarter 2016 pricing basis. The results showed that 14.46 kg/h of juice could be produced from fresh Napier grass stem with potential ethanol yield of 9.27 (w/w). About 82% protein relative to the initial protein content in the sample could be recovered in addition to 49 kg/h bagasse (45 wt% moisture), which are important valuable products. The total capital cost of $2.63 M (million USD) and operating cost/year of $0.24 M is required for the process plant with option of solid residue drying while $1.45 M and $ 0.17 M was recorded for the second scenario. The investment analysis at 25-year economic life of the project showed the corresponding net present value (NPV) of $2.93 M and $5.55 M at 7% and 15% internal rate of return (IRR). Consequently, the process scenarios represent alternative on-site pre-processing of Napier grass biomass with potential additional economic value.

Long‐term Biomass and Potential Ethanol Yields of Annual and Perennial Biofuel Crops

Core Ideas Annual crops produced a third more biomass and three times as much ethanol as perennials. Perennial crops used half as much nitrogen fertilizer as annual crops. Grain from most annual crops enhanced ethanol production per unit of biomass. Sweet sorghum produced substantially more ethanol than all other crops. Sorghum yielded more biomass and potential ethanol than corn in hot, dry years. Although energy crops could eventually supply a growing portion of cellulosic biofuel feedstocks, long‐term comparisons of annual and perennial crops are rare. An experiment was established in 2007 near Manhattan, KS, to compare biomass productivity and ethanol yield of perennial and annual crops. Perennial crops included three C4 grasses: switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), and miscanthus (Miscanthus sacchariflorus). Annual C4 crops were corn (Zea mays L.) in two rotations: continuous and rotated with soybean [Glycine max (L.) Merr.]; and five types of sorghum [Sorghum bicolor (L.) Moench]: photoperiod sensitive, sweet, dual purpose (grain and biomass), brown mid‐rib, and grain; all rotated with soybean. Annual crops produced 7 Mg ha−1 yr−1 more biomass than perennial crops throughout 11 yr, with sweet sorghum exceeding 22 Mg ha−1 yr−1, and 12 m3 ha−1 yr−1 of ethanol. Biomass yield of miscanthus approached 14 Mg ha−1 yr−1, essentially the same as for several annual crops but with half as much fertilizer nitrogen. Annual ethanol production from miscanthus and switchgrass was 3.6 m3 ha−1 yr−1, half as much as that of several annual crops that produced similar biomass yields. Big bluestem consistently produced the least biomass and ethanol, less than 7 Mg ha−1 yr−1 and 1.7 m3 ha−1 yr−1, respectively. Rotated corn averaged 7.1 m3 ha−1 yr−1 of ethanol. Eleven years of results indicate that annual corn and sorghum crops as well as perennial grasses such as miscanthus and switchgrass could play a role as potential bioenergy feedstocks in diversified production systems.

Performance of bmr 6 and 12 Sorghum Mutants in Different Wild Backgrounds Under Salinity

Sorghum is one of the bioenergy crops, with considerable tolerance to salinity. The current work was undertaken to assess the salinity tolerance of brown midrib (bmr) mutant lines and wild parents for biomass composition and potential theoretical ethanol yield (TEY). The variation for salinity levels in field plots was significant; hence, salinity screening under controlled environment was performed. The mutant line N 600 (bmr-12) had performed better under field screening (at 10 dS m−1) with fresh stalk yield of 17.3 t ha−1, dry stalk yield of 7.4 t ha−1, and grain yield of 2.0 t ha−1. The performance of bmr-6 and bmr-12 mutant alleles showed that bmr-12 allele, i.e., N 597 and N 600 had performed better than its wild types EHS and Atlas, respectively, for relative fresh and dry biomass index at 20, 40 and 80 days after imposing 150 mM salinity stress. The lines N 597 (13.05 cm2 g−1), N 596 (6.84 cm2 g−1) and N 593 (7.39 cm2 g−1) recorded the highest specific leaf area at 20, 40 and 80 days of stress, respectively. High membrane stability index was recorded in mutants N 596 (bmr-6-85.33%) and N 597 (bmr-12-84.78%) with EHS though under different genetic background under stress. Higher TEY was recorded in N 597 (2219.82 L ha−1), N 600 (2159.79 L ha−1), N 595 (2019.03 L ha−1) and N 598 (1945.33 L ha−1) under stressed conditions, with a moderate reduction of 47.85 and 47.50% in 2014 and 2015, respectively, in TEY.

Sweet Sorghum Response to Magnesium Fertilization and Top Removal

Sweet sorghum (Sorghum bicolor (L.) Moench) can be considered as a cash crop in arid and semiarid regions. High production of syrup, sugar and ethanol yield has made the sweet sorghum an important crop in many developing programs. In this study, the effects of crop top removal, including mechanical, and chemical removal along with intact plants as control with spraying magnesium sulfate (0, 4 and 8 mM) were investigated on juice extraction, sugar content and potential ethanol yield of two sweet sorghum varieties (KFS2, KFS3). Our results indicated that juice extraction increased by top removal and application of magnesium sulfate, ranged from 13.1 to 23.4 m3 ha−1. Mechanical and chemical top removal along with spraying magnesium sulfate resulted in greater sucrose and total sugar compared to intact plants. Traits determined in study were identical between 4 and 8 mM magnesium sulfate levels; thus, 4 mM level could apply as the optimum level. In comparison, between the two varieties, KFS3 produced higher amount of extracted juice, juice production efficiency, glucose and potential ethanol yield. Ethephon showed positive effects on juice amount and sugar content as same as mechanical removal. Based on these results, it is suitable to use chemical flowering inhibitors, according to their easy application than mechanical removal. It is concluded that magnesium supply and manipulation of flowering procedure may cause higher sugar accumulation in stalks which is more beneficial for ethanol fermentation.

Improving Biomass and Ethanol Yield by Intercropping a Winter Cereal with Corn

Core Ideas Incorporation of a cover crop improved ethanol and biomass yield regardless of harvest time. Stover‐only treatments yielded greater ethanol and biomass when harvest in the fall. Despite differences in fermentable sugars among feedstocks, biomass yield was the strongest driver of per hectare ethanol yield. Corn (Zea mays L.) stover is readily available and can be used as a feedstock for cellulosic ethanol. The addition of a winter annual cereal crop to the corn stover system could increase potential ethanol yield by adding harvestable biomass. The objective of this study was to evaluate the potential bioethanol yield resulting from the harvest of mixed stands of corn stover interseeded with winter cereals. The winter cereal crop factor consisted of three treatments; cereal rye (Secale cereale L.), triticale (Triticale hexaploide Lart.), and no winter cereal crop (control). The harvest time factor consisted of two treatments; a two‐harvest system (fall + spring), and a one‐harvest system (fall or spring). Two‐harvest feedstock ethanol content [EtOH] was the greatest (0.305 kg kg−1 and 0.307k g kg−1) followed by the spring‐harvested stover (0.201 kg kg−1). Biomass production and [EtOH] were then multiplied to calculate ethanol yields. Ethanol yield (L ha−1) decreased by 47% when stover‐only feedstock was harvested in the spring compared to the fall. When only considering a single harvest system, incorporation of a cover crop did improve ethanol yield by 242 L ha−1 at spring harvest. The two‐harvest mixed feedstock system was the most productive with 41.8% greater ethanol yield when compared to the single harvest. Overall, the mixed biomass feedstocks resulting from the incorporation of a winter annual cereal with corn stover improved biomass yield and [EtOH] relative to stover‐only feedstocks.

Switchgrass Biomass Composition Traits and their Effects on its Digestion by Ruminants and Bioconversion to Ethanol

Six generations of divergent breeding in switchgrass (Panicum virgatum L.) for forage in vitro digestibility (IVDMD) resulted in significant changes in 20 biomass composition traits. Stepwise multiregression was used to determine which of the 20 composition traits had the largest significant effects on forage IVDMD and potential ethanol yield (ETOH) in a biorefinery. Switchgrass biomass samples from a field nursery containing the divergent switchgrass populations and families were harvested after flowering, dried, ground, and analyzed for composition traits by near‐infrared reflectance analyses using previously developed near‐infrared reflectance calibrations. After nonsignificant variables were eliminated, the resulting multiple regression models were highly significant (P < 0.001) and accounted for 95 and 96%, respectively, of the total variation for both IVDMD and ETOH. Standardized partial regression coefficients were used to estimate the relative importance of each significant variable. The biomass composition factors that had the largest impact on both IVDMD and ETOH were esterified ferulates, p‐coumarate esters, specific cell wall sugars that are involved in the linkage of cell wall lignin to hemicellulose, N, and extracted fats. Klason lignin was not a significant variable in either regression analysis, even though it was strongly negatively correlated with both IVDMD and ETOH. The IVDMD test, which acted as a biological selection index in a long‐term population breeding program, impacted an array of switchgrass biomass composition traits whose relative effects on both IVDMD and ETOH had not been previously quantified.

Potential of Nypa palm as a complementary biomass crop to oil palm in Malaysia

Throughout the world, there have been attempts to diversify sources of renewable energy including biomass resources. In Malaysia, the main biomass source is oil palm (94%). However, there exists a number of underutilised biomass species which could provide abundant, sustainable, ecosystem resilient and cost effective sources of biomass for renewable energy in addition to oil palm. This research aims to explore the potential of a novel biomass crop to mitigate the overdependence on oil palm as a source of biomass. Nypa palm (Nypa fruticans) is a monospecific genus palm endemic to estuaries in the South-East Asia region. In the past, the sap from this palm was traditionally harvested for beverages while leaflets was used in roofing thatching. However, these practices are slowly dwindling as local opt for higher paid jobs. Historically, alcohol from Nypa sap was used as fuel before World War II but this local industry collapsed at the arrival of the oil economy. Recent studies examining for new fuel alternatives suggested that Nypa sap has the potential to become a bioethanol feedstock. In particular, its high sugar content has been reported to have a potential ethanol yield of 8,200-15,400 L ha-1 y-1 under optimum conditions, which is higher than current yields obtained for commercial sugarcane or maize. Nypa also has potential as a lignocellulosic feedstock for conversion into multiple products, particularly for industrial (green chemicals) and medicinal purposes. Studies on genetic diversity, plantation management and cost analysis for biofuel production are lacking and needed to be carried out. This paper explores the potential of the crop to be a complementary source of biomass production to oil palm.

Utilization of whole sorghum crop residues for bioethanol production

Sorghum is the fifth most important cereal worldwide and is a major source of agricultural residues in tropical regions. Bioconversion of whole sorghum crop residues comprising stalks, leaves, peduncles and panicles to ethanol has great potential for improving ethanol yield per sorghum crop cultivated, and for sustainable biofuel production. Effective pretreatment of sorghum lignocellulosic biomass is central to the efficiency of subsequent fermentation to ethanol. Previous studies have focused on the bioconversion of sorghum stalks and/or leaves only to bioethanol, but the current study is the first report dealing with whole crop residues. We specifically focused on the impact of Nigerian sorghum cultivation location and cultivar type on the potential ethanol yield from whole sorghum crop residues. Efficient bioconversion of whole sorghum residues to ethanol provides a sustainable route for utilization of crop residues thereby providing a non-food feedstock for industrial-scale bioethanol production. Copyright © 2016 The Institute of Brewing & Distilling

Corn stover ethanol yield as affected by grain yield, Bt trait, and environment

Literature values for glucose release from corn stover are highly variable which would likely result in tremendous variability in bio-refinery ethanol yield from corn stover feedstock. A relatively recent change in United States corn genetics is the inclusion of the Bacillus thuringiensis (Bt) trait, which now accounts for three-fourths of all US planted corn acreage. The objective of this study was to evaluate the effect of corn grain yield, inclusion of the Bt trait, and location environment on corn stover quality for subsequent ethanol conversion. Two hybrid pairs (each having a Bt and non-Bt near-isoline) were analyzed giving a total of 4 hybrids. In 2010 and 2011, field plots were located in Michigan at four latitudinal differing locations in four replicated plots at each location. Stover composition and enzymatic digestibility was analyzed and estimated ethanol yield (g g−1) was calculated based on hydrolyzable glucan and xylan levels. Analysis showed that there were no significant differences in total glucose or xylose levels nor in enzymatically hydrolyzable glucan and xylan concentrations between Bt corn stover and the non-Bt stover isolines. Regression analyses between corn grain yield (Mg ha−1) and corn stover ethanol yield (g g−1) showed an inverse relationship indicative of a photosynthate source-sink relationship. Nevertheless, the quantity of stover produced was found to be more critical than the quality of stover produced in maximizing potential stover ethanol yield on a land area basis.

Chemical composition and potential ethanol yield of Jerusalem artichoke in a semi-arid region of China

The study was aimed to evaluate the potential of existing genotypes of Jerusalem artichoke (Helianthus tuberosus L.) as biomass feedstock for ethanol production. We investigated the biomass productivity and chemical composition of twenty-six Jerusalem artichoke clones grown in a semi-arid region of China. Jerusalem artichoke was demonstrated to be a sustainable feedstock for bioethanol production. All structural and non-structural carbohydrates in whole plant of Jerusalem artichoke could be 5000 L/ha. The above-ground biomass of Jerusalem artichoke could be a promising feedstock for cellulosic ethanol. The ethanol potential yield from cellulose and hemicellulose in aboveground biomass were 1821 to 5930 L/ha, contributing 29.8-66.4% of the total ethanol yield, which could be as high as that from switchgrass and sweet sorghum stem. Large variation among the investigated genotypes for carbohydrates makes it possible to select suitable clones to be used in bioethanol production in semiarid regions. Clones HB-3, HEN-3, IM-1, SC-1, SHX-3, SX-2 and ZJ-2 yielded tuber total soluble sugar higher than 4.0 t/ha. Clones BJ-4, HUB-2, HUN-2, QH-1, SD-2 and SHH-1 produced more than 5.0 t/ha cellulose and hemicellulose in above-ground biomass. Clones BJ-4 and HUB-2 have the highest ethanol potential based on structural carbohydrates. These clones were promising material if used as biofuel feedstock in this growth condition.

Nitrogen and Tillage Management Affect Corn Cellulosic Yield, Composition, and Ethanol Potential

Corn (Zea mays L.) stover and cobs remaining after grain harvest can serve as a feedstock for cellulosic ethanol production. Field trials were conducted at two locations in Minnesota over three years to determine how corn cellulosic yield composition and ethanol yield are influenced by tillage system [chisel tillage (CT), strip-tillage (ST), and no-tillage (NT)] and fertilizer N rate (0, 45, 90, 134, 179, and 234 kg N ha−1). Stover biomass yield, C and N concentrations and content, and potential ethanol yield increased with increasing fertilizer N rate. Stover biomass yield, C content, and potential cellulosic ethanol yield were less with NT than CT and ST by ≥9, 8, and 8 %, respectively. Theoretical ethanol yield of stover was maximized at a fertilizer N rate lower than the economically optimum N rate (EONR) for grain yield. Cob biomass yield, C concentration and content, N concentration, and potential ethanol yield increased with fertilizer N rate, but not at the same magnitude observed for stover. Tillage system did not influence cob biomass yield, C and N concentrations and content, or potential ethanol yield. These results demonstrate that biomass and ethanol production of stover and cobs can be affected by N and tillage management. Cobs may be a more viable feedstock option than stover because nearly all measured variables were less sensitive to management and their harvest removes less C and N from a field compared to full harvest of combined cobs and stover.

Response of Sweet Sorghum Genotypes for Biomass, Grain Yield and Ethanol Production under Different Fertility Levels in Rainfed Conditions

Sweet sorghum (Sorghum bicolor (L.) Moench.) is a promising bio-energy crop and has potential to complement sugarcane production in diversified cropping systems. The objective of the present study was to assess the relative performance of advance open pollinated varieties (OPVs) for biomass, juice yield, quality traits, grain and bio-ethanol yields, and profitability under different fertility levels and locations. The performance of two advance OPVs (SPV 2074 and SPV 2075) was compared with check variety CSV 19SS and hybrid CSH 22SS under four fertility levels (80:40:40; 60:30:30, 40:20:20 kg N: P2O5: K2O ha−1 and control) at Indore (Madhya Pradesh), Pantnagar (Uttarakhand) and Palem (Andhra Pradesh). Treatments were replicated thrice in a factorial randomized block design. Plant height increased significantly (P ≤ 0.05) with increasing fertility levels. Test genotype SPV 2075 had the tallest plant (290 cm). Application of RDF (80:40:40 kg NPK ha−1) reduced the number of days required for 50 % flowering by 3 days as compared to control. Test genotypes flowered 3 days earlier than the check CSV 19SS. Application of 80:40:40 kg NPK ha−1 increased the grain yield by 153 % over control and the test variety CSV 2074 produced 108 % higher grain yield than the check CSV 19SS. Fresh stalk yield, juice and potential ethanol yields were also increased with application of RDF. SPV 2074 and SPV 2075 produced higher juice yields as compared to check CSV 19SS. Juice yield was significantly (P ≤ 0.01) and positively correlated with plant height (r = 0.667**) and fresh stalk yield (r = 0.721**). Maximum net returns (US $ 473.44 ha−1) and B: C ratio (2.09) were observed in plots treated with RDF (80:40:40 kg NPK ha−1). The test varieties SPV 2074 and SPV 2075 produced 93.8 and 56 % higher net returns as compared to check CSV 19SS.

Switchgrass Response to Cutting Frequency and Biosolids Amendment: Biomass Yield, Feedstock Quality, and Theoretical Ethanol Yield

Biofuel crops have relatively low economic value, and potential to grow them with low-cost inputs is essential for economic viability. Use of biosolids as a fertility source has not been explored at the field scale for switchgrass (Panicum virgatum L.), a potential bioenergy crop. This study tested harvest management and biosolids rate effects on switchgrass production, quality, and theoretical ethanol yield in Virginia, USA. Switchgrass (cv. “Cave-in-Rock”) was annually cut once (winter) or twice (summer and winter) for 2 years. Biosolids were applied once at 0, 77, and 154 kg N ha−1 in May 2011; urea was applied once at 146 kg N ha−1 for comparison. Feedstock yield and quality parameters (neutral and acid detergent fibers, cellulose, hemicellulose, lignin, and ash) were measured and used to compute theoretical ethanol potential (TEP) and theoretical ethanol yield (TEY). Cutting twice per season produced greater biomass yields than cutting once (6.6 vs 5.4 Mg ha−1) in 2011 but not in 2012. Cutting once per season produced feedstock with greater TEP (513 vs 433 L Mg−1) and TEY (2,980 vs 2,680 L ha−1) in both years. Biosolids and urea increased biomass yields by 11 % (0.6 Mg ha−1) and TEY by 13 % (352 L Mg−1), but both decreased TEP by 1 % (7.1 L Mg−1 biomass). Cutting once per season is advantageous in producing more TEY given comparable biomass yield and superior feedstock quality. Biosolids were a suitable alternate N source and could boost biomass and biofuel production while reducing input costs in switchgrass-based bioenergy systems.

Biomass production and potential ethanol yields of shrub willow hybrids and native willow accessions after a single 3-year harvest cycle on marginal lands in central Minnesota, USA

Short rotation woody crops are being developed as a sustainable source of biomass for the production of bioenergy, biofuels, and bioproducts. With the potential increase in demand of biomass for energy in the future, there is a need to diversify and expand its source. In the present study, we evaluated the growth performance, biomass production, energy content, and potential ethanol yields of shrub willow hybrids and native willow accessions. Shrub willow hybrids cuttings were obtained from the State University of New York through its controlled breeding program while cuttings used for native willow accessions were collected naturally. At the end of one rotation, consisting of three growing seasons, we found that shrub willow hybrids outperformed native willow accession species (P = 0.0004), with an average survival rate of 80 and 39 %, respectively. Biomass production of shrub willow hybrids and native willow accessions ranged from 7.42 to 16.0 and from 0.69 to 1.83 Mg ha−1 oven dry weight, respectively. The chemical composition (mass fraction % on dry basis) of willow hybrids and native willow accessions generally contained 39 % cellulose, 19 % hemicellulose, 25 % lignin, 1.4 % ash content, 17,500–18,500 kJ kg wood−1, and 385 L Mg−1 of theoretical ethanol yield. Energy content and potential ethanol yields on a dry weight basis did not vary between shrub willow hybrids and native willow accessions; however, the amount of biomass produced per unit land area is known to influence potential ethanol yields. Thus, we suggest that shrub willow hybrids offer promising potential as an alternative source of biomass. The results of our study suggest that four of the shrub willow hybrids evaluated have a greater potential for use as biomass energy crops on marginal lands in central Minnesota than the native willow accessions; hence, there is a need to test their potential at a larger scale.

Growth environment, harvest management and germplasm impacts on potential ethanol and crude protein yield in alfalfa

An alfalfa (Medicago sativa L) biomass energy production system would produce two products. Leaves would be separated from stems to produce a protein feed for livestock while stems would be processed to produce ethanol. Therefore, maximum yields of both leaves and stems are essential for profitability of this biomass production system. Our objective was to evaluate the impact of growth environment (locations, years and plant density) and harvest maturity stage (early bud (4 annual cuts) and late flower (3 annual cuts)) on leaf crude protein and potential ethanol yields for four alfalfa germplasms, two with high forage quality, and two non-lodging biomass types. Potential ethanol yield was greater at late flower compared to early bud, while leaf crude protein concentration was similar at the two harvest maturity stages at both locations. Leaf crude protein yield was greater at the Minnesota (MN) site compared to Wisconsin (WI) site. The two non-lodging biomass germplasms had greater potential ethanol yield compared to the high forage quality cultivars in WI, but no differences among the alfalfa germplasms were found for ethanol yield at MN. In WI, no differences were found among the germplasms for leaf crude protein yield, but the high quality cultivars had greater leaf crude protein yield than the non-lodging germplasms in MN. While germplasm differences were found for leaf crude protein and potential ethanol yields, the environmental influences of harvest date and locations had the greatest impact on these two alfalfa biomass energy products.

Comparing oxidative and dilute acid wet explosion pretreatment of Cocksfoot grass at high dry matter concentration for cellulosic ethanol production

AbstractThe choice of a suitable pretreatment method and the adjustment of the pretreatment parameters for efficient conversion of biomass are crucial for a successful biorefinery concept. In this study, cocksfoot grass, a suitable lignocellulosic biomass with a potential for large‐scale production was investigated for cellulosic ethanol production. The biomass raw materials were pretreated using wet explosion (WEx) at 25% dry matter concentration with addition of oxygen or dilute sulfuric acid. The enzymatic hydrolysis of cellulose was significantly improved after pretreatment. The highest conversion into cellulose monomeric C6 sugars was achieved for WEx condition AC‐E (180°C, 15 min, and 0.2% sulfuric acid). For that condition, the highest ethanol yield of 197 g/kg DM (97% of theoretical maximum value) was achieved for SSF process by Saccharomyces cerevisiae. However, the highest concentration of hemicellulose C5 sugars was found for WEx pretreatment condition O2‐A (160°C, 15 min, and 6 bar O2) which means that the highest potential ethanol yield was found at this moderate pretreatment condition with oxygen added. Increasing the pretreatment temperature to 180–190°C with addition of oxygen or dilute sulfuric acid significantly degrades the solubilized hemicellulose sugars and thus, achieved the highest formation of by‐products.