Production Of Liquid Biofuels Research Articles

Soil application of high-lignin fermentation byproduct to increase the sustainability of liquid biofuel production from crop residues

Abstract When digestates from anaerobic digestion of crop residues are added to soil, a considerable body of information indicates that soil organic carbon (SOC) levels are comparable to those when crop residues are left in the field. This occurs although the amount of digestate added to soil is diminished by digestion and implies that digestion increases the proportion of carbon inputs stabilized as SOC. Here we examine the likelihood and implications of these features being manifested for soil application of high lignin-fermentation byproduct (HLFB) from liquid biofuel production. We show that steady-state SOC levels are much less sensitive to crop residue removal with HLFB return than without it, and provide an example supporting the feasibility of foregoing process energy and coproduct revenue when HLFB is returned to the soil. Informed by this review and analysis, we expect with moderate confidence that long-term SOC levels for soils amended with HLFB from some liquid cellulosic biofuel processes will be similar to those occurring when crop residues are left in the field. We have high confidence that the economically optimum rate of fertilizer nitrogen (N) application and N2O emissions will be lower at most sites for HLFB return to the soil than if crop residues were left in the field. We estimate that the per hectare N demand for processing crop residues to liquid biofuels is about a third of the per hectare demand for crop production, giving rise to an opportunity to use N twice and thereby realize cost savings and environmental benefits. These observations support but do not prove the hypothesis that a "win-win" is possible wherein large amounts of liquid biofuel feedstock can be obtained from crop residues while improving the economics and sustainability of food and feed production. A research agenda aimed at exploring and testing this hypothesis is offered.

Biofuel production from macrophytes

The depletion of natural resources and minerals is leading to slower economic growth in many countries. Sustainable economic development requires rational resource management and waste reduction, as disposal or incineration pollutes fertile soils, the atmosphere, and water bodies. This study aimed to develop methods for obtaining the technology of liquid biofuel (bio-oil) production by hydrothermal revitalization of the biomass of macroalgae and aquatic macrophytes. The thermal properties and caloric content of aquatic plant biomass, specifically Phragmites australis, Scirpus lacustris, Typha angustifolia L., and Sparganium erectum L., were investigated, and the optimal parameters for hydrothermal revitalization of their biomass were identified. The biomass of P. australis and S. lacustris was shown to have optimal thermal properties, having an ash content of 7.6% and 6.6%, respectively, and a maximum mass loss temperature of 351 °C and 345 °C, respectively. The production regimes for liquid biofuel (bio-oil) were established. The properties of fuel derived from P. australis biomass were evaluated, including the content of easily boiling fractions and coke residue. The magnitude of fuel yield from biomass P. australis was found to be correlated with the quality of bio-oil. Thus, obtaining biofuels from aquatic plants is one of the promising areas of plant biomass processing.

Possibilities of Utilising Biomass Collected from Road Verges to Produce Biogas and Biodiesel

Grass collected as part of roadside maintenance is conventionally subjected to composting, which has the disadvantage of generating significant CO2 emissions. Thus, it is crucial to find an alternative method for the utilisation of grass waste. The aim of this study was to determine the specific biogas yield (SBY) from the anaerobic mono-digestion of grass from road verges and to assess the content of Fatty Acid Methyl Esters (FAMEs) in grass in relation to the time of cutting and the preservation method of the studied material. The biochemical biogas potential (BBP) test and the FAMEs content were performed on fresh and ensiled grass collected in spring, summer, and autumn. The highest biogas production was obtained from fresh grass cut in spring (715.05 ± 26.43 NL kgVS−1), while the minimum SBY was observed for fresh grass cut in summer (540.19 ± 24.32 NL kgVS−1). The methane (CH4) content in the biogas ranged between 55.0 ± 2.0% and 60.0 ± 1.0%. The contents of ammonia (NH3) and hydrogen sulphide (H2S) in biogas remained below the threshold values for these inhibitors. The highest level of total FAMEs was determined in fresh grass cut in autumn (98.08 ± 19.25 mg gDM−1), while the lowest level was detected in fresh grass cut in spring (56.37 ± 7.03 mg gDM−1). C16:0 and C18:0, which are ideal for biofuel production, were present in the largest amount (66.87 ± 15.56 mg gDM−1) in fresh grass cut in autumn. The ensiling process significantly impacted the content of total FAMEs in spring grass, leading to a reduction in total saturated fatty acids (SFAs) and an increase in total unsaturated fatty acids (USFAs). We conclude that grass biomass collected during the maintenance of road verges is a valuable feedstock for the production of both liquid and gaseous biofuels; however, generating energy from biogas appears to be more efficient than producing biodiesel.

Physicochemical exploration of castor seed oil for high-quality biodiesel production and its sustainable application in agricultural diesel engines

In Thailand, castor seeds often classified as weeds are locally distributed in every region of the country and not fully utilized. Therefore, this research aimed to study the physicochemical properties of castor seed oil as a raw material for the production of liquid biofuels. The study of extracting oil from castor seeds using various methods revealed that the Soxhlet extraction technique, a circulatory extraction method, yielded the highest amount of extracted oil at 52.45 wt%, compared to the dry weight of the castor seed. In the study of the physicochemical properties of castor seed oil, the results revealed that the major components were 89.71% ricinoleic acid, 3.96% linoleic acid, and 3.09% oleic acid, respectively. The kinematic viscosity of castor seed oil was as high as 164.68 cSt. However, when converted into castor seed oil biodiesel, the kinematic viscosity decreased to 10.36 cSt, still two times higher than that of the standard biodiesel oil. Therefore, blending castor seed oil biodiesel with petroleum diesel oil to obtain B30 and B40 revealed that the fuel properties met the qualifications of both ASTM D6751 and EN 14214 standards. The initial tests on agricultural diesel engines found that the gas emissions of CO2, CO, HC, and NO2 from biodiesel blends B30 and B40 tend to be lower than those from using only petroleum diesel oil and biodiesel oil derived from castor seeds. Therefore, blending biodiesel oils B30 and B40, derived from castor seed oil, not only results in good biofuel liquid qualities but also proves to be efficient for use in agricultural diesel engines. It is suitable to encourage the community to adopt it for agricultural purposes in the future.

Lipidomic analysis of microalgae and its application in microalgae cultivation and alternative liquid biofuel production

Lipidomic analysis of microalgae and its application in microalgae cultivation and alternative liquid biofuel production

Multi-objective optimization of syngas production for Fischer-Tropsch synthesis based on biogas catalytic reforming and upgrading

The conversion of biogas into synthesis gas, for its subsequent application in Fischer-Tropsch synthesis, is one of the most studied processes for the production of liquid biofuels. However, this conversion still has economic and environmental disadvantages. This study evaluated the technical feasibility of a syngas production plant from biogas upgrading and reforming, through water scrubbing and bi-reforming processes. Aspen Plus modeling and a multi-objective optimization (MOO) were used to minimize CO2 emissions and maximize profitability. The multi-objective differential evolution with tabu list method was used to resolve the MOO design problem. The results reveal inherent trade-offs between both objectives. In particular, certain process parameters exerted a notable influence on the outcomes. Keeping a low water flow in the absorption column is essential to reduce environmental impact, but this also results in a lesser removal of impurities from biogas. Conversely, a higher water flow in the reactor promotes methane conversion, but concurrently raises the environmental impact. Nevertheless, the profitability of the Pareto front ranged from 5,200 to 6,500 k$ with a 1,000 Nm³/h biogas feed and the calculated CO2 equivalent net flow values varied between -11,900 and -11,550 kg/h. Therefore, it was successfully validated that calculated solutions of the Pareto allowed to demonstrate the feasibility of the proposed process.

Biochar‐based catalysts derived from biomass waste: production, characterization, and application for liquid biofuel synthesis

AbstractAmong the feasible options for valorizing lignocellulosic biomass into value‐added products, biochar is considered to be extremely appealing and it could be applied easily in several established thermochemical processes. Biochar possesses a large surface area due to its porous nature, which permits easy use in various applications, including catalytic biofuel production. This work summarizes research on biochar generation processes, its critical physicochemical properties, and factors that influence them. Important studies adopting biochar catalysts for liquid biofuel production are critically reviewed, and the reaction mechanisms and biofuel yield are analyzed. Finally, challenges in the use of biochar‐based catalysts for biofuel production are presented, together with possible solutions. In general, this current work aims to provide the critical characteristics of biochar as a potential catalyst to biofuel synthesis toward sustainable bioenergy production.

Characterizing the Opportunity Space for Sustainable Hydrothermal Valorization of Wet Organic Wastes.

Resource recovery from wet organic wastes can support circular economies by creating financial incentives to produce renewable energy and return nutrients to agriculture. In this study, we characterize the potential for hydrothermal liquefaction (HTL)-based resource recovery systems to advance the economic and environmental sustainability of wastewater sludge, FOG (fats, oils, and grease), food waste, green waste, and animal manure management through the production of liquid biofuels (naphtha, diesel), fertilizers (struvite, ammonium sulfate), and power (heat, electricity). From the waste management perspective, median costs range from -193 $·tonne-1 (FOG) to 251 $·tonne-1 (green waste), and median carbon intensities range from 367 kg CO2 eq·tonne-1 (wastewater sludge) to 769 kg CO2 eq·tonne-1 (green waste). From the fuel production perspective, the minimum selling price of renewable diesel blendstocks are within the commercial diesel price range (2.37 to 5.81 $·gal-1) and have a lower carbon intensity than petroleum diesel (101 kg CO2 eq·MMBTU-1). Finally, through uncertainty analysis and Monte Carlo filtering, we set specific targets (i.e., achieve wastewater sludge-to-biocrude yield >0.440) for the future development of hydrothermal waste management system components. Overall, our work demonstrates the potential of HTL-based resource recovery systems to reduce the costs and carbon intensity of resource-rich organic wastes.

Life-cycle assessment of microalgae liquid biofuel production in biofilm cultivation system via conversion technologies of transesterification, hydrothermal liquefaction and pyrolysis

Biofilm seems to be an ideal cultivation system for microalgae liquid biofuel conversion technologies due to the advantage of high biomass concentration. However, research on the biofilm cultivation system for microalgae liquid biofuel producing were limited. In this study, a life-cycle assessment was conducted for microalgae liquid biofuel production in this system via three conversion technologies: transesterification, hydrothermal liquefaction and pyrolysis. The result shows that scenario hydrothermal liquefaction seems to be the most feasible technology to produce liquid biofuel in biofilm system because only hydrothermal liquefaction achieved positive energy and environment benefits with a net energy ratio of 0.87 and Greenhouse gas emissions of −39.91 g CO2-eq MJ−1. For transesterification and pyrolysis, the net energy ratio (2.18 and 2.06) were larger than 1, while Greenhouse gas emissions (3.28 and 59.25 g CO2-eq) were greater than 0. This indicated that these scenarios exhibited negative energy and environment benefits due to heavy use of chemicals and high energy consumption during biomass drying process, respectively. Additionally, according to the sensitivity analysis, bio-crude mass yield exhibited a more significant impact on the energy and environment loads for scenario hydrothermal liquefaction than the other factors.

Evaluation of available adsorbents for the dry washing of the wasted frying oil based crude ethyl esters

Russia's invasion of Ukraine strongly actualized the issue of liquid biofuels production. Ethyl esters biodiesel may be produced from widely available domestic Ukrainian oils and locally produced bioethanol. Dry washing with adsorbents is an advanced biodiesel purification technique. There is still a lack of information on the dry washing of alkaline ethanolysis products, especially concerning the removal of heavy contaminants, originating from partially polymerized waste oils. Current work deals with the investigation of available materials as adsorbents for the purification of crude ethyl esters (88% esters, 1.61% monoacylglycerols, 0.73% diacylglycerols, 0.19% tryacylglyceroles, 1.04% soaps, 0.12% fatty acids, 1.07% glycerol, and 0.17% ethanol). Esters were prepared via alkaline-catalyzed transesterification of wasted frying sunflower oil (2.46 mg KOH/g, 7.1% palmitic, 3.5% stearic, 27.7% oleic, and 59.3% linoleic acids). Activated anthracite, synthetic carbon Chemviron, colloidal silica, meta-kaolin, talc, and bentonite were evaluated as adsorbents. All samples provided the removal of the majority of soaps and glycerol, decreased the ethanol concentration, and, in most cases, acid value. Dry washing had almost no impact on the acylglycerols content. Activated carbons, characterized by a combination of developed micro- and mesoporosity, produced the greatest results, including a minor amount of monoacylglycerols removal. However, none of the adsorbents provided the removal of heavy oligomer contaminants, which is indirectly indicated by no higher than 90% esters content in treated samples. Improvement of these characteristics may be achieved by vacuum distillation.

Agricultural biomass feedstock for biofuels production in Ukraine

Ukraine has a large potential of biomass available for the production of solid, gaseous and liquid biofuels. According to 2021 data, the bioenergy potential is about 25 Mtoe, of which 49% is agricultural residues and 30% is energy crops (in case of growing on 2 mln ha). Of the agriresidues, only sunflower husk is now widely used for energy, while the potential of straw, corn stalks and sunflower stalks is practically untapped for this purpose. For Ukraine, one of the promising directions is priority use of corn stalks for the production of energy and solid biofuels such as briquettes and pellets. Another prospective area is growing energy crops. Ukraine has 3-4 mln ha of unused (marginal) agricultural land, which can be engaged for growing energy crops such as willow, poplar, miscanthus (for solid biofuels) and corn silage for biogas. Growing energy crops as biomass feedstock and its further use for the production of heat and power becomes competitive in light of growing prices of natural gas and issues with providing security of its supply. An important but less-developed sector of Ukraine’s bioenergy is motor biofuels. Having such a big potential of agribiomass, the country could produce bioethanol and biodiesel including the advanced biofuels from lignocellulosic feedstock. It is necessary to create favourable conditions for the development of domestic production of motor biofuels. This may include a reduction in the excise tax, the abolition of compulsory tax bill for the full rate of excise duty when transporting bioethanol, the introduction of an export duty on rapeseed, and some other measures.

Maximizing Liquid Fuel Production from Reformed Biogas by Kinetic Studies and Optimization of Fischer–Tropsch Reactions

In the current work, the operating conditions for the Fischer–Tropsch process were optimized using experimental testing, kinetic modelling, simulation, and optimization. The experiments were carried out using a Ce-Co/SiO2 catalyst to examine how operating parameters affected the conversion of CO and product selectivity. A power-law kinetic model was used to represent the reaction rates in a mathematical model that was created to replicate the Fischer–Tropsch synthesis (FTS). It was decided to estimate the kinetic parameters using a genetic optimization technique. The developed model was validated for a range of operating conditions, including a temperature range of 200–240 °C, a pressure range of 5–25 bar, a H2/CO ratio of 0.5–4, and a space velocity range of 1000–5000 mL/gcat·h. The mean absolute relative error (MARE) between the experimental and predicted results was found to be 11.7%, indicating good agreement between the experimental data and the predicted results obtained by the mathematical model. Optimization was applied to maximize the production of liquid biofuels (C5+). The maximum C5+ selectivity was 91.66, achieved at an operating temperature of 200 °C, reactor total pressure of 6.29 bar, space velocity of 1529.58 mL/gcat·h, and a H2/CO feed ratio of 3.96. The practical implications of the present study are maximizing liquid biofuel production from biomass and municipal solid waste (MSW) as a renewable energy source to meet energy requirements, reducing greenhouse gas emissions, and waste management.

PROSPECTS FOR THE PRODUCTION OF ADVANCED BIOFUELS IN UKRAINE

Perspective directions for the development of motor biofuels market in Ukraine are considered. It is shown that Ukraine has a significant potential for the production of liquid biofuels for the transport sector. Today, it is mainly biodiesel and bioethanol of the first generation, since the technologies for obtaining advanced biofuels from lignocellulosic feedstocks are not yet sufficiently developed in the country. However, as these technologies improve, one of directions for the development of motor biofuels market will be the expansion of production opportunities for second generation (advanced) biofuels with a significant share of their export to EU countries. Directive (EU) 2018/2001 on renewable energy sources (RED II) limits the share of 1st generation biofuels in achieving the goals for the consumption of renewable energy in transport. The share of such biofuels in a certain EU country can be no more than 1 % higher than the share of these biofuels in the gross final energy consumption of road and rail transport of that country in 2020, but no more than 7 %. For Ukraine, this means that the share of 1st generation biofuels in the final energy consumption in transport in 2030 cannot exceed 1.85 %, since in 2020 this indicator was 0.85 %. A possible option for solving this problem is to coordinate with the European Commission the issue of increasing the quota of 1st generation biofuels for Ukraine to 7 % in 2030, which is equivalent to the consumption of 503 ktoe/y. In the future, it seems appropriate to develop the production of advanced bioethanol from byproducts of grain corn cultivation as well as advanced biodiesel from oilseed energy crops grown on unused agricultural land. According to RED II, such biodiesel is not subject to restrictions on biofuels produced from food or feed crops. Production and consumption of biomethane is also a promising direction for the introduction of renewable energy in transport. It is shown that the total potential of biogas production in Ukraine is currently 8.16 Mtoe/y, of which a quarter can be allocated for the transport needs. By 2050, the production potential of biogas as a motor fuel may increase to 4.7 Mtoe/y, mainly due to the use of cover crops as feedstock to obtain biogas. Bibl. 21, Tab. 4.

Ukraine`s Bioenergy Sector: Trends and Perspectives for the Post-war Green Energy Transition

The paper investigates trends in bioenergy development in Ukraine and its role in accelerating the green energy transition in the post-war period. The focus of the article is on the use of bioenergy resources for electricity generation, heat energy and liquid biofuel production. In this context, the potential of biomass, state support mechanisms, the results of their influence on bioenergy capacities deployment and the barriers restraining this sector development are considered. The study’s results proved that the inconsistency of the state policy and the failure to consider the specifics of energy production based on various bioenergy resources caused a significant lag in its development compared to other renewable energy technologies. With this in mind, the article systematizes strengths and weaknesses, opportunities and threats, and based on them, strategic recommendations for bioenergy development in Ukraine in the post-war period are developed.

Biomethanol production from renewable resources: a sustainable approach.

The abundant availability of various kinds of biomass and their use as feedstock for the production of gaseous and liquid biofuels has been considered a viable, eco-friendly, and sustainable mode of energy generation. Gaseous fuels like biogas and liquid fuels, e.g., bioethanol, biodiesel, and biomethanol derived from biological sources, have been theorized to produce numerous industrially relevant organic compounds replacing the traditional practice of employing fossil fuels as a raw material. Among the biofuels explored, biomethanol has shown promising potential to be a future product addressing multifactorial issues concerning sustainable energy and associated process developments. The presented mini-review has explored the importance and application of biomethanol as a value-added product. The biomethanol production process was well reviewed by focusing on different thermochemical and biochemical conversion processes. Syngas and biogas have been acknowledged as potential resources for biomethanol synthesis. The emphasis on biochemical processes is laid on the principal metabolic pathways and enzymatic machinery involved or used by microbial physiology to convert feedstock into biomethanol under normal temperature and pressure conditions. The advantage of minimizing the cost of production by utilizing suggested modifications to the overall process of biomethanol production that involves metabolic and genetic engineering in microbial strains used in the production process has been delineated. The challenges that exist in our current knowledge domain, impeding large-scale commercial production potential of biomethanol at a cost-effective rate, and strategies to overcome them along with its future scenarios have also been pointed out.

Waste-to-Energy Pipeline through Consolidated Fermentation–Microbial Fuel Cell (MFC) System

The rise in population, urbanization, and industrial developments have led to a substantial increase in waste generation and energy demand, posing significant challenges for waste management as well as energy conservation and production. Bioenergy conversions have been merged as advanced, sustainable, and integrated solutions for these issues, encompassing energy generation and waste upcycling of different types of organic waste. Municipal solid waste (MSW) and agricultural residues (AR) are two main resources for bioenergy conversions. Bioenergy production involves feedstock deconstruction and the conversion of platform chemicals to energy products. This review provides a detailed overview of waste sources, biofuel, and bioelectricity production from fermentation and microbial fuel cell (MFC) technology, and their economic and environmental perspectives. Fermentation plays a critical role in liquid biofuel production, while MFCs demonstrate promising potential for simultaneous production of electricity and hydrogen. Fermentation and MFCs hold a significant potential to be integrated into a single pipeline, enabling the conversion of organic matter, including a variety of waste material and effluent, into diverse forms of bioenergy via microbial cultures under mild conditions. Furthermore, MFCs are deemed a promising technology for pollutant remediation, reducing COD levels while producing bioenergy. Importantly, the consolidated fermentation–MFC system is projected to produce approximately 7.17 trillion L of bioethanol and 6.12 × 104 MW/m2 of bioelectricity from MSW and AR annually, contributing over USD 465 billion to the global energy market. Such an integrated system has the potential to initiate a circular economy, foster waste reduction, and improve waste management practices. This advancement could play a crucial role in promoting sustainability across the environmental and energy sectors.

Production of Liquid Biofuel Precursors: Optimization and Regulation of Lipase Fermentation and Its Application in Plant Oil Hydrolysis Process

In the liquid biofuel production process, free fatty acids are important precursors for biodiesel and bio-aviation fuel. Enzymatic hydrolysis to produce free fatty acids has attracted more and more attention. However, enzymatic hydrolysis requires ensuring efficient expression of lipase and high product yield. In the shaking flask, the optimal addition amount of citric acid was 3 g/L, and the composition of composite amino acids was: histidine 0.1 mol/L, aspartic acid 0.03 mol/L and lysine 0.03 mol/L. On the basis of the shaking flask optimization, a 5 L fermentation tank was scaled up to obtain 25,000 U/mL of lipase after multiple batches of stable fermentation. This was the first time to cultivate Y. lipolytica using composite amino acid medium to produce high enzyme-activity lipase, demonstrating the industrial value of this lipase fermentation process. Finally, soybean oil was hydrolyzed to produce free fatty acids on a self-made static reactor. The optimized reaction conditions were: material flow rate 2813 mL/min, reaction temperature 45 °C, water content 25 wt% and lipase consumption 3 wt%. The yield of free fatty acids was 80.63% after 12 h under optimal reaction conditions in the self-made static reactor, 11.95% higher than that in the stirred reactor, which showed its industrial potential in the production of free fatty acids.

Catalytic co-liquefaction of microalgae + corn straw over K3PO4+γ-Al2O3 supported Fe and Ni mono- / bimetallic in-situ composite catalysts for the production of liquid biofuel

In the present study, an array of K3PO4 + γ-Al2O3 supported Fe and Ni in-situ composite catalysts including K3PO4-Fe/γ-Al2O3, K3PO4-Ni/γ-Al2O3, K3PO4-Fe-Ni/γ-Al2O3 were prepared and characterized by Nitrogen-physisorption, XRD, XPS, NH3-TPD, H2-TPR, SEM, and TEM analysis. The effects of catalyst type, catalysts loading, feedstock loading and the ratio between corn straw and spirulina on the products yield and distribution from co-hydrothermal liquefaction of spirulina and corn straw were investigated. The greater specific surface area, larger amount of medium acid sites, the key roles of K and Fe-Ni bimetallic system and enhanced interaction between Fe, Ni and γ-Al2O3 support of K3PO4-Fe-Ni/γ-Al2O3 are mainly responsible for the greatest amount of water-insoluble (35.73 wt%) and water-soluble (2.18 wt%) biocrude. Besides, the optimal reaction condition (5 wt% catalysts loading, 10 wt% feedstock loading and spirulina: corn straw = 1:1 w/w) was confirmed. The presence of catalysts especially for K3PO4-Fe-Ni/γ-Al2O3 significantly increased the energy recovery of biocrude. Meanwhile, K3PO4-Fe-Ni/γ-Al2O3 noticeably increased the fraction of lighter molecule in biocrude up to 57.18 wt%. The esters, phenols and N-heterocyclic compounds were found to be dominated in biocrude from all co-HTL cases, and the enhanced selectivity to esters with catalysts were observed. Finally, the prospective reaction pathway and mechanism of the catalytic co-HTL of spirulina and corn straw was proposed and discussed detailly and comprehensively.

Use of Artificial Neural Networks to Model Biomass Properties of Miscanthus (Miscanthus × giganteus) and Virginia Mallow (Sida hermaphrodita L.) in View of Harvest Season

Miscanthus and Virginia Mallow are energy crops characterized by high yields, perenniality, and low agrotechnical requirements and have great potential for solid and liquid biofuel production. Later harvest dates result in lower yields but better-quality mass for combustion, while on the other hand, when biomass is used for biogas production, harvesting in the autumn gives better results due to lower lignin content and higher moisture content. The aim of this work was to determine not only the influence of the harvest date on the energetic properties but also how accurately artificial neural networks can predict the given parameters. The yield of dry matter in the first year of experimentation for this research was on average twice as high in spring compared to autumn for Miscanthus (40 t/ha to 20 t/ha) and for Virginia Mallow (11 t/ha to 8 t/ha). Miscanthus contained 52.62% carbon in the spring, which is also the highest percentage determined in this study, while Virginia Mallow contained 51.51% carbon. For both crops studied, delaying the harvest date had a positive effect on ash content, such that the ash content of Miscanthus in the spring was about 1.5%, while in the autumn it was 2.2%. Harvest date had a significant effect on the increase of lignin in both plants, while Miscanthus also showed an increase in cellulose from 47.42% in autumn to 53.5% in spring. Artificial neural networks used to predict higher and lower heating values showed good results with lower errors when values obtained from biomass elemental composition were used as input parameters than those obtained from proximity analysis.

Potential use of Sotol bagasse (Dasylirion spp.) as a new biomass source for liquid biofuels production: Comprehensive characterization and ABE fermentation

This study presents a physico-chemical characterization of bagasse obtained from the artisanal and industrial production of Sotol. The last was employed as feedstock for acetone-butanol-ethanol (ABE) fermentation using Clostridium beijerinckii. Chemical analyses revealed a significant presence of CaC₂O₄, and levels of inorganic elements close to or above the limits established in ISO 16968:2015. These, together with their calorific values that are below other lignocellulosic materials, limit the use of sotol bagasse as solid biofuel. Structural characterization exhibited that the industrial sotol bagasse contained cellulose with lower crystallinity, thus easing its bioavailability for microorganisms to perform ABE fermentation. It was possible to obtain acetone, butanol, and ethanol (0.94 ± 0.05 g/L, 1.97 ± 0.52 g/L and 1.90 ± 0.40 g/L, respectively) using industrial sotol bagasse as substrate for C. beijerinckii. Then a scale-up of ABE fermentation was carried out to obtain information on ABE yield and Clostridium growth kinetics at different working volumes. ABE yield was lower the scale-up experiment (0.31 ± 0.02 g/g) compared to the obtained with smaller working volume (0.48 ± 0.07 g/g). These results offer crucial insights into the potential use of industrial sotol bagasse as a novel renewable feedstock to obtain biofuels throughout ABE fermentation.