Bioenergy Feedstock Research Articles

Evaluating black wattle bark industrial residue as a new feedstock for bioenergy via pyrolysis and multicomponent kinetic modeling

This work presents an evaluation of the industrial residue from exhausted black wattle bark after the extraction of tannin for use as a new feedstock for biofuel production, without competing with food production. The physicochemical and thermodynamic properties, the influence of temperature on pyrolysis products and multicomponent kinetics were evaluated. Principal component analysis showed that sugars, carboxylic acids, ethers/esters, furans and aldehydes were formed as primary products of pyrolysis at 450 °C. At 550 °C, phenols and mainly ketones were favored, especially acetone and 2,3-butanedione. Pyrolysis at 650 °C favored the production of aldehydes, alcohols, and 1-alkene, polyene and alkane hydrocarbons. After an upgrade, the series of 1-alkenes produced, with carbons C7 to C16, could be suitable for a range of gasoline and jet fuels. Kinetic modeling was based on the deconvolution of the mass loss of three events of the pseudo-components: hemicellulose (DE-HC), cellulose (DE-CL) and lignin (DE-LG). The activation energy for kinetic models Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Starink presented average values of ∼141.4–149.4 for DE-HC, ∼190.5–200.9 for DE-CL and ∼237.2–252.3 kJ mol−1 for DE-LG. This study encourages using agro-industrial waste to produce second-generation drop-in biofuels and bio-based chemicals, aiming at industrial decarbonization.

Integrated sensing and machine learning: Predicting saccharine and bioenergy feedstocks in sugarcane

Predicting saccharine and bioenergy feedstocks in sugarcane enables growers and industries to determine the precise time and location for harvesting a better-quality product in the field. On one hand, Brix, Purity, and total recoverable sugars (TRS) can provide meaningful and reliable indicators of high-quality raw materials for first-generation (1 G) bioethanol. Conversely, Cellulose, Hemicellulose, and Lignin are the primary constituents of straw, directly contributing to second-generation (2G) bioethanol. However, analyzing these materials in the laboratory is a time-consuming and non-scalable task. Therefore, we propose an approach based on a multi-sensor framework, which includes multispectral unmanned aerial vehicle (UAV) imagery, thermal, photosynthetic active radiation (PAR), and chlorophyll fluorescence (ChlF) data, along with machine learning (ML) algorithms namely random forest (RF), multiple linear regression (MLR), decision tree (DT), and support vector machine (SVM), to develop a non-invasive and predictive framework for mapping sugarcane feedstocks. We collected samples of stalks and leaves/straw during the maturity stage while simultaneously collecting remote sensing data. The ML models played a crucial role in predicting 1 G (R2 = 0.88–0.93) and 2 G (R2 = 0.56–0.82) feedstocks. Notably, remote sensing data could serve as important features for the models, mainly through the spectral bands (Blue, Green, and RedEdge), DTemp and ChlF. Hence, the best features can be further implemented within a framework to predict sugarcane feedstocks. Our study marks a significant advancement in the industrial-scale prediction of sugarcane feedstocks, providing stakeholders with invaluable prescriptive harvesting strategies for both primary products and by-products.

Shear rate dependency on flowing granular biomass material

The commercialization of bioenergy has been significantly limited by various material handling issues due to the poor flowability of granular biomass materials. Addressing these issues demands a fundamental understanding of flow physics and robust models to predict the multi-regime flow behavior of biomass particles. In this study, we investigated the multi-regime flow behavior of loblolly pine chips, a widely used bioenergy feedstock, through combined experiments and simulations. A quasi-static hypoplastic model and a cross-regime Drucker–Prager (DP)-μ(I) model were utilized and validated against inclined plane flow experiments to understand the quasi-static and dense flow behavior of milled pine chips. The results show that along the inclined plane, loblolly pine chips mainly present in heap flow (varying thickness along the plane), and in plane flow (iso-thickness along the plane) only when the inclination closes to the material’s critical state internal friction angle. The results also show that the multi-regime DP-μ(I) model predicts a completely different velocity profile from the hypoplastic model. DP-μ(I) model can capture the flow behavior of pine chips in both flow regimes well but at the cost of extra parameter determination, and the shear-rate dependent rheology model can successfully capture the flow of elongated high-frictional particles. These findings advance the scientific understanding of the multi-regime flow behavior of granular biomass materials and shed light on formulating novel constitutive models to assist granular biomass handling in the bioenergy industry.

Development and utilization of genome-wide InDel markers in Sorghum [Sorghum bicolor (L.) Moench

Sorghum (Sorghum bicolor L. Moench) has become an increasingly valuable crop for food, feed, and especially bioenergy feedstock production, which makes the crop extremely attractive for studying genomics and genetic diversity. Molecular markers and genomics play essential roles in sorghum breeding. The rapid development of next-generation sequencing technology has facilitated the identification of genome-wide insertion-deletion (InDel) polymorphisms, enabling the efficient construction of InDel markers that are suitable for user-friendly PCR. This study was conducted with the objective of discovering and developing InDel markers using double digest restriction site-associated DNA sequencing (ddRAD-Seq) data. A total of 19,226 InDels distributed across 10 chromosomes in the sorghum genome was identified. Of those, deletions constituted 65.7% while the remain was insertions. A comprehensive analysis of all the chromosomes revealed a total of 80 InDel sites with a minimum length of 10 bp. For a good conversion of the InDel regions to beneficial molecular markers, specific primers were designed for the amplification of 47 InDel regions that were selected for further investigation. A diverse panel of sorghum consisting of 16 accessions served a source for the developed InDel markers validation. Of the 47 InDel markers, 14 were tested across 16 sorghum accessions and were demonstrated their helpfulness for marker-assisted selection in sorghum. The polymorphic information content (PIC) values of the 16 markers varied between 0.11 and 0.38, with an average of 0.28. The findings of this study indicated that the identification of InDels and the development of molecular markers for sorghum were accomplished using the ddRAD-Seq data.

A multi-omic survey of black cottonwood tissues highlights coordinated transcriptomic and metabolomic mechanisms for plant adaptation to phosphorus deficiency.

Phosphorus (P) deficiency in plants creates a variety of metabolic perturbations that decrease photosynthesis and growth. Phosphorus deficiency is especially challenging for the production of bioenergy feedstock plantation species, such as poplars (Populus spp.), where fertilization may not be practically or economically feasible. While the phenotypic effects of P deficiency are well known, the molecular mechanisms underlying whole-plant and tissue-specific responses to P deficiency, and in particular the responses of commercially valuable hardwoods, are less studied. We used a multi-tissue and multi-omics approach using transcriptomic, proteomic, and metabolomic analyses of the leaves and roots of black cottonwood (Populus trichocarpa) seedlings grown under P-deficient (5 µM P) and replete (100 µM P) conditions to assess this knowledge gap and to identify potential gene targets for selection for P efficiency. In comparison to seedlings grown at 100 µM P, P-deficient seedlings exhibited reduced dry biomass, altered chlorophyll fluorescence, and reduced tissue P concentrations. In line with these observations, growth, C metabolism, and photosynthesis pathways were downregulated in the transcriptome of the P-deficient plants. Additionally, we found evidence of strong lipid remodeling in the leaves. Metabolomic data showed that the roots of P-deficient plants had a greater relative abundance of phosphate ion, which may reflect extensive degradation of P-rich metabolites in plants exposed to long-term P-deficiency. With the notable exception of the KEGG pathway for Starch and Sucrose Metabolism (map00500), the responses of the transcriptome and the metabolome to P deficiency were consistent with one another. No significant changes in the proteome were detected in response to P deficiency. Collectively, our multi-omic and multi-tissue approach enabled the identification of important metabolic and regulatory pathways regulated across tissues at the molecular level that will be important avenues to further evaluate for P efficiency. These included stress-mediating systems associated with reactive oxygen species maintenance, lipid remodeling within tissues, and systems involved in P scavenging from the rhizosphere.

Post-harvest regeneration is driven by ecological factors rather than wood procurement intensity in eastern Canadian forests

Abstract Biomass from surplus forest growth that is not harvested for wood supply of conventional industries can be an important source of feedstock for bioenergy. Its procurement can be integrated with little effort into current harvest operations. However, the increasing harvesting intensity to meet greater demand for biomass procurement can impact forest ecosystem functions because of its direct and indirect effects on woody debris and the regeneration of next-rotation stands. In this context, we aimed to determine the relationships between wood procurement intensity, woody debris inputs, and regeneration success over 2 years after harvesting. We tested four treatments of increasing wood procurement intensity using a randomized block design within six experimental sites along a gradient of varying forest characteristics of boreal and temperate forests. We assessed stand characteristics in terms of standing trees, woody debris, and regeneration pre- and post-harvest. We used mixed effects models to evaluate (i) the effects of wood procurement intensity and pre-harvest stand characteristics on the volume and cover of woody debris and (ii) the specific influence of woody debris on the presence of suitable planting microsites post-harvest. Furthermore, we used principal component regressions to explore the relationships between harvesting intensity and the presence of natural regeneration and competing vegetation as a function of pre- and post-harvest stand characteristics (iii). Our results showed that increasing wood procurement intensity reduced the volume of post-harvest woody debris while having a limited effect on regeneration. Increasing harvesting intensity had a negligible effect on suitable planting microsites in hardwood-dominated stands but it increased their presence in conifer-dominated stands. Natural regeneration and competing vegetation were mainly related to stand characteristics, and only broadleaf regeneration was sensitive to harvest intensity. We conclude that the relationships between wood procurement intensity and regeneration are complex and rely mainly on stand characteristics rather than wood procurement needs.

Delignification of Different Lignocellulosic Biomass Using Hydrogen Peroxide and Acetic Acid (HPAC)

Lignocellulosic biomass will soon become the key source of feedstock for bioenergy to combat the impact of global warming and the depletion of fossil fuel resources. Lignin separation costs have been a key obstacle to bioenergy generation from lignocellulosic biomass. Pulp and paper, biofuel, and biomaterials sectors depend on wood delignification. This study examines delignification trends and advances, including standard and new methods. The study begins by explaining how delignification improves wood processability and value. It describes lignin's chemical structure and properties, highlighting its role in wood's mechanical and chemical qualities. Lignin from diverse lignocellulosic biomass sources is delignified using hydrogen peroxide and acetic acid in this study. A 1:1 hydrogen peroxide-acetic acid volume ratio was used after particle reduction. Experimental results show 96%, 89%, and 80% lignin removal efficiency for Ako, Mahogany, and mixed sawdust, respectively. A 30-minute reaction at 80°C yielded these results. The hydrogen peroxide-acetic acid mixture dignifies well and may be used in lignocellulosic biomass processing. This study also provides insights into optimizing delignification procedures and suggests approaches to improve the industrial use of lignocellulosic biomass. This study reveals that HPAC dignifies wood well. Understanding HPAC's role in the delignification of wood products could lead to developing an HPAC-based pretreatment technique that lowers the cost of biofuel generation from lignocellulosic biomass.

Reparameterizing Litter Decomposition Using a Simplified Monte Carlo Method Improves Litter Decay Simulated by a Microbial Model and Alters Bioenergy Soil Carbon Estimates

AbstractLitter decomposition determines soil organic matter (SOM) formation and plant‐available nutrient cycles. Therefore, accurate model representation of litter decomposition is critical to improving soil carbon (C) projections of bioenergy feedstocks. Soil C models that simulate microbial physiology (i.e., microbial models) are new to bioenergy agriculture, and their parameterization is often based on small datasets or manual calibration to reach benchmarks. Here, we reparameterized litter decomposition in a microbial soil C model (CORPSE ‐ Carbon, Organisms, Rhizosphere, and Protection in the Soil Environment) using the continental‐scale Long‐term Inter‐site Decomposition Experiment Team (LIDET) dataset which documents decomposition across a range of litter qualities over a decade. We conducted a simplified Monte Carlo simulation that constrained parameter values to reduce computational costs. The LIDET‐derived parameters improved modeled C and nitrogen (N) remaining, decomposition rates, and litter mean residence times as compared to Baseline parameters. We applied the LIDET litter decomposition parameters to a microbial bioenergy model (Fixation and Uptake of Nitrogen – Bioenergy Carbon, Rhizosphere, Organisms, and Protection) to examine soil C estimates generated by Baseline and LIDET parameters. LIDET parameters increased estimated soil C in bioenergy feedstocks, with even greater increases under elevated plant inputs (i.e., by increasing residue, N fertilization). This was due to the integrated effects of plant litter quantity, quality, and agricultural practices (tillage, fertilization). Collectively, we developed a simple framework for using large‐scale datasets to inform the parameterization of microbial models that impacts projections of soil C for bioenergy feedstocks.

Biomass production of 14 accessions of cactus pear (Opuntia spp.) under semi‐arid land conditions

AbstractIncreased food, feed, and biofuel demands of the future will require a greater reliance upon crop production systems in arid and semi‐arid regions around the world. Diminishing freshwater resources and hotter and drier climatic conditions will also necessitate the use of highly drought tolerant and water‐use efficient crops. Cactus pear (Opuntia ficus‐indica) is a low‐water input, climate‐resilient crop capable of high biomass production due to its use of crassulacean acid metabolism (CAM). Cactus pear produces both food and forage/fodder, a wide variety of high‐value byproducts, and serves as a bioenergy feedstock for biogas or bioethanol production. Here, we evaluated the biomass productivity of 14 Opuntia spp. accessions from the National Arid Land Plant Genetic Resources Unit (NALPGRU) in Parlier, CA under semi‐arid conditions with a planting density of 6667 plants ha−1 over a 3‐year period to identify high‐yielding biomass producers. Mean annual cladode fresh weight (CFW) (73.7 Mg ha−1 year−1), cladode dry weight (CDW) (5.2 Mg ha−1 year−1), and cladode count (CC) (10.5 cladodes plant−1) increased by 2.9‐, 2.8‐, and 2.8‐fold in year 3 compared with year 1. PARL 845, hybrid no. 46 (O. ficus‐indica × O. lindheimerii), showed the highest annual mean CFW (152.8 Mg ha−1 year−1), CDW (13.3 Mg ha−1 year−1), CC (22.1 cladodes plant−1), and dry matter content (DMC, 11.2%) among all accessions tested. Non‐hybrid accessions PARL 242 (O. cochenillifera), PARL 582 (Opuntia sp.), and PARL 584 (Opuntia sp.) showed 100% cladode establishment rates and CDW productivity of >6 Mg ha−1 year−1. Such biomass productivity results indicate that cactus pear displays great potential as a crop with many uses with lower water inputs than conventional crops for arid and semi‐arid environments.

Bioenergy feedstock supply from wheat straw: A farm level model incorporating trade‐offs in crop choices, disease risk, and soil fertility

AbstractSecond‐generation biofuel (e.g., ethanol, renewable diesel) can be made from crop residues. However, the availability of residues for biofuel production is uncertain, because farmers have the option to grow different crops and use the residues for alternative purposes, such as livestock bedding and feed, or leave them in the field to improve soil quality. Taking Canadian wheat straw supply as an example, we develop a dynamic programming model to investigate a farmer's wheat straw supply decision in response to different wheat straw and grain prices. Our model considers crop choices between wheat and canola in the context of disease risk, the trade‐off between the immediate payoffs a farmer may receive from bailing and selling wheat straw, and the long‐term adverse effects that removing wheat straw from the soil surface may have on wheat and canola yields. The results from this study provide insights into how farm‐level supply decisions, in response to wheat straw price changes, affect soil quality dynamics and scale up to regional wheat straw supply for biofuel production. This information also has implications for land use change and the sustainability of feedstock supply for biofuels.

Genome-wide identification and characterization of greenbug-inducible NAC transcription factors in sorghum.

Sorghum (Sorghum bicolor) is an important cereal crop grown worldwide because of its multipurpose uses such as food, forage, and bioenergy feedstock and its wide range of adaption even in marginal environments. Greenbug can cause severe damage to sorghum plants and yield loss. Plant NAC transcription factors (TFs) have been reported to have diverse functions in plant development and plant defense but hasnot beenstudied in sorghum yet. In this study, a comprehensive analysis of the sorghum NAC (SbNAC) gene family was conducted through genome-wide analysis. A total of 112 NAC genes has been identified in the sorghum genome. These SbNAC genes are phylogenetically clustered into 15 distinct subfamilies and unevenly distribute in clusters at the telomeric ends of each chromosome. Twelve pairs of SbNAC genes are possibly involved in the segmental duplication among nine chromosomes except chromosome 10. Structure analysis showed the diverse structures with a highly variable number of exons in the SbNAC genes. Furthermore, most of the SbNAC genes showed specific temporal and spatial expression patterns according to the results of RNA-seq analysis, suggesting their diverse functions during sorghum growth and development. We have also identified nine greenbug-inducible SbNAC genes by comparing the expression profiles between two sorghum genotypes (susceptible BTx623 and resistant PI607900) in response to greenbug infestation. Our systematic analysis of the NAC gene expression profiles provides both a preliminary survey into their roles in plant defense against insect pests and a useful reference for in-depth characterization of the SbNAC genes and the regulatory network that contributes genetic resistance to aphids.

Pyrolysis kinetics behavior and pyrolysate compositions analysis of agriculture waste toward the production of sustainable renewable fuel and chemicals

AbstractThis work deals with the characterization of feed, kinetic, and compositional study of sugarcane baggage (SCB) using a thermogravimetric analyzer (TGA), Py‐GC‐MS, and X‐ray fluorescence (XRF) analyzer. XRF analyzer was used to determine the mineral of ash content, and Py‐GC‐MS was employed to determine the hot vapor composition produced during fast pyrolysis. Cots‐Redfrem (CR) methods and master plots were utilized to determine the kinetic parameters. Studies on the physicochemical properties of SCB have demonstrated its potential for use as a bioenergy feedstock. The average activation energy was found to be 25.44 kJ mol−1 at (n = 1) and 31.21 kJ mol−1 at n ≠ 1 using the CR model. The master plot study suggested that pyrolysis occurred with various mechanisms, while kinetic results of SCB demonstrated that activation energy varied with conversion value. XRF examination revealed significant mineral materials that aided in the pyrolysis process. Finally, the introduction of ZSM‐5 at 20 wt % results increased hydrocarbons (~3 wt %), furfurelas (~4 wt %) and reduced the phenols (~15 wt %), acid (~9 wt %) and oxygnetaed compounds. The present study showed that introducing zeolite catalysts improved pyrolysis products' properties.

Cattle wastewater treatment using green microalga Coelastrella sp. KNUA068 as a promising bioenergy feedstock with enhanced biodiesel quality.

Global water scarcity increased the demand for clean water, leading to attention on microalgae-based biological treatment for wastewater due to economic feasibility and sustainable biomass applications. This study isolated indigenous microalga Coelastrella sp. KNUA068 from a wastewater treatment plant, observed its admissible growth rate in diluted cattle wastewater (DCW), and used it for wastewater treatment analysis. The microalga showed high growth rates in indoor and outdoor cultivation with 100% DCW. In addition, the ammonia nitrogen and nitrate nitrogen removal rates of the microalga were 69.97 and 60.35%, respectively, in indoor cultivation, and 50.63 and 67.20%, respectively, in outdoor cultivation. Carotenoid content analysis revealed lutein as the highest productivity carotenoid, and zeaxanthin production was higher in outdoor cultivation. The biomass exhibited suitable biodiesel quality with a cetane number of 50.8 for high-quality biodiesel production. Coelastrella sp. KNUA068 demonstrates potential for bioenergy feedstock, carotenoid production, and wastewater treatment.

Perennializing marginal croplands: going back to the future to mitigate climate change with resilient biobased feedstocks

Managing annual row crops on marginally productive croplands can be environmentally unsustainable and result in variable economic returns. Incorporating perennial bioenergy feedstocks into marginally productive cropland can engender ecosystem services and enhance climate resiliency while also diversifying farm incomes. We use one of the oldest bioenergy-specific field experiments in North America to evaluate economically and environmentally sustainable management practices for growing perennial grasses on marginal cropland. This long-term field trial called 9804 was established in 1998 in eastern Nebraska and compared the productivity and sustainability of corn (Zea mays L.)—both corn grain and corn stover—and switchgrass (Panicum virgatum L.) bioenergy systems under different harvest strategies and nitrogen (N) fertilizer rates. This experiment demonstrated that switchgrass, compared to corn, is a reliable and sustainable bioenergy feedstock. This experiment has been a catalyst for other bioenergy projects which have also expanded our understanding of growing and managing bioenergy feedstocks on marginal cropland. We (1) synthesize research from this long-term experiment and (2) provide perspective concerning both the knowledge gained from this experiment and knowledge gaps and how to fill them as well as the role switchgrass will play in the future of bioenergy.

Chemical Composition of the Aboveground Tissues of Miscanthus × giganteus and Relationships to Soil Characteristics

To reduce the C footprint of human activities, there is a growing need for alternative energy sources including the production of bioenergy feedstocks. Miscanthus × giganteus is a high yielding grass with low environmental impact and high potential for feedstock use. Studying the composition of the aboveground tissues of Miscanthus is important for understanding feedstock quality for biofuel conversion and how crop residue quality may affect soil input management. Data on Miscanthus leaf and stem chemistry including carbon (C), nitrogen (N), macronutrient concentrations, and the optical characteristics of the water extractable organic matter (WEOM) was analyzed to identify differences in composition between aboveground tissues and modeled to identify soil variables that may be correlated with tissue chemistry. Leaves and stems were dominated by N, potassium (K), calcium (Ca), phosphorus (P), and magnesium (Mg), but overall, the leaves contained higher nutrient concentrations compared to the stems. The leaves displayed elevated Si:K (0.0935) and Ca:K (0.445) ratios and lower C:N (36) and C:P (323) ratios compared to the stems (0.0560, 0.145, 150, and 645, respectively). Leaf WEOM contained large, aromatic, and complex structures, while the stem WEOM was dominated by small, recently produced structures. Varying relationships were found between tissue C and the mobile C pool in surface (0–15 cm) and deep (45–60 cm) soils. Overall, Miscanthus leaves had a chemical composition indicative of reduced biofuel quality compared to the stems. The relationships with soil mobile C suggest a dynamic linkage between Miscanthus physiology and this active soil C pool. These results have implications for crop nutrient allocation and nutrient management practices.

Sustainable strategies to achieve industrial ethanol titers from different bioenergy feedstocks: scale-up approach for better ethanol yield

Hydrothermal pretreatment is a promising approach to lignocellulosic biomass processing for enzymatic hydrolysis and high-yield bioethanol fermentation, as it reduces downstream inhibitor content and the amount of toxic byproducts generated.

Long–term rotational and perennial cropping benefit soil organic carbon stocks and ecosystem multifunctionality

Multipurpose cropping is promoted to provide biomass to meet the growing demand for biorefining, but excessive biomass removal may decrease soil C stocks and ecosystem multifunctionality. Here, soil C stocks across 0–200 cm depth and soil ecosystem multifunctionality at 0–40 cm were evaluated based on a 19–year field experiment, including three multipurpose cropping systems as continuous cotton (CC), ryegrass–sweet sorghum double cropping (RS) and perennial switchgrass (SG). Compared to CC, RS and SG increased the soil C stocks by 19% and 28%, and N stocks by 19% and 23% at 0–200 cm, respectively. The soil C stocks were positively correlated with belowground C input and negatively associated with C mineralization. RS and SG increased soil ecosystem multifunctionality by 16.8 and 15.7 folds at 0–20 cm and 0.34 and 0.61 folds at 20–40 cm relative to CC, respectively. The benefit of soil C stocks and ecosystem multifunctionality was more pronounced in SG than in RS due to the deeper root system. In conclusion, relative to continuous monoculture, rotational and perennial cropping can enhance soil C sequestration, maintain soil function, and provide feedstock for bioenergy.

Impact of bioenergy feedstock carbon farming on sustainable aviation fuel viability in the United States.

Biomass-derived sustainable aviation fuel holds significant potential for decarbonizing the aviation sector. Its long-term viability depends on crop choice, longevity of soil organic carbon (SOC) sequestration, and the biomass-to-biojet fuel conversion efficiency. We explored the impact of fuel price and SOC value on viable biojet fuel production scale by integrating an agroecosystem model with a field-to-biojet fuel production process model for 1,4-dimethylcyclooctane (DMCO), a representative high-performance biojet fuel molecule, from Miscanthus, sorghum, and switchgrass. Assigning monetary value to SOC sequestration results in substantially different outcomes than an increased fuel selling price. If SOC accumulation is valued at $185/ton CO2, planting Miscanthus for conversion to DMCO would be economically cost-competitive across 66% of croplands across the continental United States (US) by 2050 if conventional jet fuel remains at $0.74/L (in 2020 US dollars). Cutting the SOC sequestration value in half reduces the viable area to 54% of cropland, and eliminating any payment for SOC shrinks the viable area to 16%. If future biojet fuel prices increase to $1.24/L-Jet A-equivalent, 48 to 58% of the total cultivated land in the United States could support a more diverse set of feedstocks including Miscanthus, sorghum, or switchgrass. Among these options, only 8-14% of the area would be suitable exclusively for Miscanthus cultivation. These findings highlight the intersection of natural solutions for carbon removal and the use of deep-rooted feedstocks for biofuels and biomanufacturing. The results underscore the need to establish clear and consistent values for SOC sequestration to enable the future bioeconomy.

Transcriptomic analysis of ncRNAs and mRNAs interactions during drought stress in switchgrass

Switchgrass (Panicum virgatum L.) plays a pivotal role as a bioenergy feedstock in the production of cellulosic ethanol and contributes significantly to enhancing ecological grasslands and soil quality. The utilization of non-coding RNAs (ncRNAs) has gained momentum in deciphering the intricate genetic responses to abiotic stress in various plant species. Nevertheless, the current research landscape lacks a comprehensive exploration of the responses of diverse ncRNAs, including long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), to drought stress in switchgrass. In this study, we employed whole transcriptome sequencing to comprehensively characterize the expression profiles of both mRNA and ncRNAs during episodes of drought stress in switchgrass. Our analysis identified a total of 12,511 mRNAs, 59 miRNAs, 38 circRNAs, and 368 lncRNAs that exhibited significant differential expression between normal and drought-treated switchgrass leaves. Notably, the majority of up-regulated mRNAs displayed pronounced enrichment within the starch and sucrose metabolism pathway, as validated through KEGG analysis. Co-expression analysis illuminated that differentially expressed (DE) lncRNAs conceivably regulated 1308 protein-coding genes in trans and 7110 protein-coding genes in cis. Furthermore, both cis- and trans-target mRNAs of DE lncRNAs exhibited enrichment in four common KEGG pathways. The intricate interplay between lncRNAs and circRNAs with miRNAs via miRNA response elements was explored within the competitive endogenous RNA (ceRNA) network framework. As a result, we constructed elaborate regulatory networks, including lncRNA-novel_miRNA480-mRNA, lncRNA-novel_miRNA304-mRNA, lncRNA/circRNA-novel_miRNA122-PvSS4, and lncRNA/circRNA-novel_miRNA14-PvSS4, and subsequently validated the functionality of the target gene, starch synthase 4 (PvSS4). Furthermore, through the overexpression of PvSS4, we ascertained its capacity to enhance drought tolerance in yeast. However, it is noteworthy that PvSS4 did not exhibit any discernible impact under salt stress conditions. These findings, as presented herein, not only contribute substantively to our understanding of ceRNA networks but also offer a basis for further investigations into their potential functions in response to drought stress in switchgrass.

Breeding of sorghum hybrids for solid biofuel

Purpose. Today, the search, research and implementation of new technologies for the production of solid fuel is important for the agro-industrial complex and renewable energy. Sorghum is considered as a strategic crop in the provision of feedstock for bioenergy and reclamation of degraded soils. The purpose of the study was to study and select the material for the creation of high-yielding hybrids of sugar and grain sorghum for the production of solid biofuel.
 Materials and methods. The two-year results of the sorghum variety test at the Synelnykivska Experimental Station are highlighted. 68 samples were studied. They had a yield of green mass in the range of 23–79 t/ha.
 Results. F1 hybrids (Nyzk.93s x Karlykove 45) formed the highest average yield of green mass — 65.2 t/ha; F1(Early776s x Karlykove 45) — 61.4 t/ha and F1(Dn71s x Karlykove 45) — 60.1 t/ha. The yield of hybrids Mammoth and F1(A158x Karlykove 45) was slightly lower, and amounted to 53.3 and 52.8 t/ha, respectively. F1 (Nyzkorosle 93s x Karlykove 45) stood out according to the average yield of dry matter of green mass — 17.6 t/ha; F1 (Dn17s x Karlykove 45) — 13.8 t/ha. According to the average indicators of the yield of solid fuel from 1 ha, the combinations F1 (Nyzk.93s x Karlykove 45) were the best — 12 t/ha; F1 (Dn17s x Karlykove 45) — 8.2 t/ha; F1 (Early 776s x Karlykov 45) — 7.9 t/ha. The best indicators in terms of energy output were the following combinations: F1(Low 93s x Karlykove 45) — 197.7 Gj/ha, F1(Dn71s x Karlykove 45) –135.5 Gj/ha, F1(Early 776s x Karlykove 45) — 129 Gj/ha.
 Conclusions. High-yielding sorghum hybrids are the most economical and energetically expedient measures to provide feedstock for the bioenergy industry. A selected hybrid for the bioenergy application F1 (Nyzkorosle 93s x Karlykove 45) differs from the standard in terms of productivity and manufacturability. The value of the Karlykove 45 variety as a pollinator for the creation of hybrids for solid biofuel was also clarified. The agricultural sector of Ukraine has enough potential resources for biofuel production.