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Globally, greater than 30% of waste is disposed of in some form of landfill, and it is estimated that annual waste-related emissions will increase by up to 76% by 2050. Emissions arising from fossil fuel-derived products and waste disposal in landfills have prompted the development of alternative technologies that utilize renewable resources. Biomass feedstock is being investigated globally to produce renewable fuels and chemicals. Globally, crop-based biomass and waste biomass are the major feedstocks for chemical production, and the market value of crop-based biomass is expected to increase at the fastest rate. South America, Europe, and North America are currently the global leaders in renewable or bio-based chemical production. In South Africa (SA), the country is still heavily reliant on landfilling as a waste solution. Wastes from agricultural production processes in SA are considered promising feedstocks for beneficiation opportunities to produce bio-based chemicals. The second-generation (2G) agricultural feedstocks that can be used in SA include fruit waste; sugarcane by-products and waste; forestry, timber, pulp, and paper waste; and invasive alien plants. Fermentation, or "green chemistry" technologies, can be used to convert various feedstocks into bio-based chemicals. Bio-based chemicals may be used as drop-in substitutes for existing petrochemical products, for use in end-user industries such as automotive and transportation, textiles, pharmaceuticals, consumer and home appliances, healthcare, and food and beverages. Bioethanol, specifically, can be used in transport fuel, as feedstock for power generation, as an energy source for fuel cells along with hydrogen, and as feedstock in the chemicals industry. Bio-butanol, an olefin derivative, can be used as a drop-in replacement for petroleum-based butanol in all its applications. Different monomers of bio-based chemicals can be used to produce biopolymers, polyhydroxyalkanoates (PHAs), and polylactic acid (PLA), which are subsequently used to produce bioplastics. A total of 25 bio-based chemicals and the technology used to produce them are summarized in this paper. Overall, bioethanol remains the dominant sugar platform product globally. Drawing on global trends, the potential options for the South African market include bioethanol, n-butanol, acetic acid, and lactic acid. It is estimated that the conversion of 70% of the lignocellulosic biomass available in SA would meet 24% of the country's liquid fuel requirement as a bioethanol equivalent. The most feasible sources of lignocellulosic biomass or waste for beneficiation in SA are generated by the agricultural sector, including sugarcane by-products and waste. Taking into consideration the abundance of lignocellulosic biomass, adequate market segment sizes, and socio-economic factors, it is apparent that there are potential opportunities to investigate the co-production of bioethanol with lactic acid or other bio-based chemicals on an industrial scale. [ABSTRACT FROM AUTHOR]

Waste banknote paper is a residue from the banking industry that cannot be recycled due to the presence of ink, microbial load and special coating that provides protection against humidity. As a result, waste banknote paper ends up being burned or buried, which brings environmental impacts, mainly caused by the presence of heavy metals in its composition. To minimize the environmental impacts that come from the disposal of waste banknote paper, this study proposes to produce value-added products (bioethanol and biogas) from waste banknote paper. For this, the effect of ink and pretreatment conditions on bioethanol and biomethane yields were analyzed. Waste banknote paper provided by the Central Bank of Iran was used. The raw material with ink (WPB) and without ink (WPD) was pretreated using sulfuric acid at different concentrations (1%, 2%, 3%, and 4%) and the nitrogen explosive decompression (NED) at different temperatures (150 °C, 170 °C, 190 °C, and 200 °C). The results show that the use of NED pretreatment in WPD resulted in the highest glucose concentration of all studies (13 ± 0.19 g/L). The acid pretreatment for WPB showed a correlation with the acid concentration. The highest ethanol concentration was obtained from the fermentation using WPD pretreated with NED (6.36 ± 0.72 g/L). The maximum methane yields varied between 136 ± 5 mol/kg TS (2% acid WPB) and 294 ± 4 mol/kg TS (3% acid WPD). Our results show that the presence of ink reduces bioethanol and biogas yields and that the chemical-free NED pretreatment is more advantageous for bioethanol and biogas production than the acid pretreatment method. Waste banknote paper without ink is a suitable feedstock for sustainable biorefinery processes. [ABSTRACT FROM AUTHOR]

By way of broadening the use of diverse sustainable bioethanol feedstocks, the potentials of Paper mulberry fruit juice (PMFJ), as a non-food, sugar-based substrate, were evaluated for fuel ethanol production. The suitability of PMFJ was proven, as maximum ethanol concentration (56.4 g/L) and yield (0.39 g/g) were achieved within half a day of the start of fermentation, corresponding to very high ethanol productivity of 4.7 g/L/hr. The established potentials were further optimally maximized through the response surface methodology (RSM). At the optimal temperature of 30 °C, yeast concentration of 0.55 g/L, and pH of 5, ethanol concentration, productivity, and yield obtained were 73.69 g/L, 4.61 g/L/hr, and 0.48 g/g, respectively. Under these ideal conditions, diverse metal salts were afterward screened for their effects on PMFJ fermentation. Based on a two-level fractional factorial design, nutrient addition had no positive impact on ethanol production. Thus, under the optimal process conditions, and without any external nutrient supplementation, bioethanol from PMFJ compared favorably with typical sugar-based energy crops, highlighting its resourcefulness as a high-value biomass resource for fuel ethanol production. [ABSTRACT FROM AUTHOR]

In the contemporary era, conventional energy sources like oil, coal, and natural gas overwhelmingly contribute 89.6% to global CO2 emissions, intensifying environmental challenges. Recognizing the urgency of addressing climate concerns, a pivotal shift towards renewable energy, encompassing solar, wind, and biofuels, is crucial for bolstering environmental sustainability. Bioethanol, a globally predominant biofuel, offers a versatile solution, replacing gasoline or integrating into gasoline–ethanol blends while serving as a fundamental building block for various valuable compounds. This review investigates the dynamic landscape of biomass generations, drawing insightful comparisons between the first, second, third, and fourth generations. Amid the drive for sustainability, the deliberate focus on the initial generation of biomass, particularly corn, in bioethanol production is grounded in the current dependence on edible crops. The established utilization of first-generation biomass, exemplified by corn, underscores the necessity for a comprehensive examination of its advantages and challenges, allowing for a nuanced exploration of existing infrastructure and practices. To produce bioethanol from corn feedstock, various milling methods can be employed. Thus, this paper delves into a comparative assessment of dry-milling and wet-milling processes scrutinizing their efficiency, environmental impact, and economic feasibility. [ABSTRACT FROM AUTHOR]

Alternative fuels especially those produced in a green way are essential for meeting supplying the world's growing energy needs. Biodiesel is becoming more prominent to meet international maritime organization regulations, minimize reliance on fossil fuels, and lessen the rising harmful emissions in the maritime sector. Four different generations have been investigated in the production stage in which a wide range of fuel types have existed including biodiesel, bioethanol, and renewable diesel. To investigate all facets of biodiesel usage as a marine fuel, the SWOT-AHP method is utilized in this paper in which 16 maritime experts with an average of 10.5 years of experience participated. SWOT factors and sub-factors have been developed in light of the literature review focused on biomass and alternative fuels. The AHP method is utilized for data acquisition from specified factors and sub-factors according to their superiority to each other. The analysis demonstrates the main factors 'PW and sub-factors' IPW values, and CR values to calculate the local and global rank of factors. Results highlighted that "Opportunity" has the highest prominence among the main factors; however, "Threats" remain at the lowest level. Moreover, "Tax privilege on green and alternative fuels supported by the authorities" (O4) is the one with the highest weight compared to the other sub-factors. Noteworthy energy consumption will be fulfilled in the maritime industry in addition to the development of new-generation biodiesel and other alternative fuels. This paper will be a quite valuable resource for experts, academics, and industry stakeholders to lessen the ambiguity around biodiesel. [ABSTRACT FROM AUTHOR]

Sago is a plant that grows naturally in some areas in Southeast and South Asia. Despite having multiple advantages, the usage of the sago palm is primarily from its starch content and is commonly used as an alternative replacement for white rice and wheat flour, the two most prominent staple foods, in several regions. Additionally, people are now more aware of how the total area of sago forests has decreased as monoculture, cash crops, or other food crop development have replaced it. This condition may endanger the ecology and the sustainability of food diversity. To support the bioeconomy principles, various utilizations of sago by turning it into higher value-added biomass need to be explored. The paper aims to review the potential utilization of sago as biomass and bioenergy as a value-added product after processing it for food. A literature review method in Scopus and PubMed databases was used to answer the research objective. Sago palm can be converted into bio-energy resources like biomass-biogas, bioelectricity, bioethanol, and biohydrogen. Together with the advancement in the processing of sago starch, sago waste from bark, pulp, fiber, or hampas is transformed into different products, e.g., plywood and particle board, sago craft from sago bark and fiber; thus, sago waste or sago hampas is a prospective bioenergy commodity. In conclusion, sago provides advantages beyond food diversity, such as lowering household food insecurity and promoting sago's use for biomass and bioenergy. [ABSTRACT FROM AUTHOR]

This document is a preface to a special issue of the journal Catalysts on the topic of catalysis in biomass valorization. The collection of papers in this issue focuses on the use of catalysis in the conversion of biomass into valuable products, addressing issues such as global warming and depletion of fossil resources. The papers cover various aspects of biomass valorization, including the use of mineral acids and microwave irradiation for biomass decomposition, enzymatic engineering of cellulase for hydrolysis, bioethanol production through fermentation, and the use of catalysts for the dehydration of butanediols. The collection reflects the diverse challenges in developing catalytic processes for biorefinery. [Extracted from the article]

Rapid growth and high carbon-fixation properties make microalgal biomass a preferred source of energy-production technologies, particularly biodiesel and bioethanol, as well as nutritional supplements and pharmaceuticals. Today, microalgal biofuel technology, which is continuing to be developed as a surrogate for fossil-fuel technology, is the focus of constant research and development, especially regarding biomass yield and lipid production. Single stressors on microalgae have been commonly examined for efficient biofuel production; however, the synergetic effects of stressors on the lipid and biomass productivity of microalgae might lead to enhanced lipid properties. In addition, considering more than one parameter might be time-consuming; thus, many models, such as the surface-response methodology, can enable significant optimization of microalgal productivity economically. As well as multiple stressors, adaptive stressors considered in "adaptive laboratory evolution" could provide robust strains that alter low lipid yields. Although the field has progressed substantially in recent years, much about microalgae, their biological potential, how to efficiently utilize them, and their metabolic responses to various stressors remain unknown. Using an extensive review of recent developments in single-stress strategies, combined-stress strategies, and adaptive stress strategies, this paper gives an overview of recent developments in microalgal biofuel production under stress conditions. Further, it has also been suggested that an integrated microalgal biorefinery that also produces high-value chemicals alongside biofuel might significantly enhance its economic feasibility. It is expected that this document will provide an understanding of how to develop commercially viable microalgae strains for biofuel applications, taking several types of stress into consideration. [ABSTRACT FROM AUTHOR]

In this paper, a simulation model based on the non-stoichiometric equilibrium method via ASPEN Plus was established to analyze the gasification performance of 20 herbaceous and agricultural biomasses (H&ABs) linked with syngas fermentation and product purification units for ethanol production. The established simulation model does not consider the gasification system as a black box; it focuses the important processes in gasification such as drying, pyrolysis, gasification, and connection with bioethanol production plants. The results for the 20 H&AB options suggest that the specific mass flow rate of bioethanol from 1 kg of biomass input to the unit is in the range of 99–250 g/kg, and between them, the system fed by hazelnut shell biomass remarkably outranked other alternatives by 241 g/kg production due to the high beneficial results gained from the performance analysis. Additionally, a sensitivity analysis was performed by changing operating conditions such as gasification temperature and air-to-fuel ratio. The modeling results are given and discussed. The established model could be a useful approach to evaluate the impacts of a huge numbers of biomasses and operating parameters on bioethanol output. [ABSTRACT FROM AUTHOR]

Most mitigation scenarios compatible with a likely change of holding global warming well below 2 °C rely on negative emissions technologies (NETs). According to the integrated assessment models (IAMs) used to produce mitigation scenarios for the IPCC reports, the NET with the greatest potential to achieve negative emissions is bioenergy with carbon capture and storage (BECCS). Crucial questions arise about where the enormous quantities of biomass needed according to the IAM scenarios could feasibly be produced in a sustainable manner. Africa is attractive in the context of BECCS because of large areas that could contribute biomass energy and indications of substantial underground CO2 storage capacities. However, estimates of large biomass availability in Africa are usually based on highly aggregated datasets, and only a few studies explore future challenges or barriers for BECCS in any detail. Based on previous research and literature, this paper analyses the pre-conditions for BECCS in Tanzania by studying what we argue are the applications of BECCS, or the components of the BECCS chain, that are most feasible in the country, namely (1) as applied to domestic sugarcane-based energy production (bioethanol), and (2) with Tanzania in a producer and re-growth role in an international BECCS chain, supplying biomass or biofuels for export to developed countries. The review reveals that a prerequisite for both options is either the existence of a functional market for emissions trading and selling, making negative emissions a viable commercial investment, or sustained investment through aid programmes. Also, historically, an important barrier to the development of production capacity of liquid biofuels for export purposes has been given by ethical dilemmas following in the wake of demand for land to facilitate production of biomass, such as sugarcane and jatropha. In these cases, conflicts over access to land and mismanagement have been more of a rule than an exception. Increased production volumes of solid biomass for export to operations that demand bioenergy, be it with or without a CCS component, is likely to give rise to similar conflicts. While BECCS may well play an important role in reducing emissions in countries with high capacity to act combined with existing large point sources of biogenic CO2 emissions, it seems prudent to proceed with utmost caution when implicating BECCS deployment in least developed countries, like Tanzania.The paper argues that negative BECCS-related emissions from Tanzania should not be assumed in global climate mitigation scenarios. [ABSTRACT FROM AUTHOR]

Background: High-throughput (HTP) screening is becoming an increasingly useful tool for collating biological data which would otherwise require the employment of excessive resources. Second generation biofuel production is one such process. HTP screening allows the investigation of large sample sets to be undertaken with increased speed and cost effectiveness. This paper outlines a methodology that will enable solid lignocellulosic substrates to be hydrolyzed and fermented at a 96-well plate scale, facilitating HTP screening of ethanol production, whilst maintaining repeatability similar to that achieved at a larger scale. Results: The results showed that utilizing sheets of biomass of consistent density (handbills), for paper, and slurries of pretreated biomass that could be pipetted allowed standardized and accurate transfers to 96-well plates to be achieved (±3.1 and 1.7%, respectively). Processing these substrates by simultaneous saccharification and fermentation (SSF) at various volumes showed no significant difference on final ethanol yields, either at standard shake flask (200 mL), universal bottle (10 mL) or 96-well plate (1 mL) scales. Substrate concentrations of up to 10% (w/v) were trialed successfully for SSFs at 1 mL volume. The methodology was successfully tested by showing the effects of steam explosion pretreatment on both oilseed rape and wheat straws. Conclusions: This methodology could be used to replace large shake flask reactions with comparatively fast 96-well plate SSF assays allowing for HTP experimentation. Additionally this method is compatible with a number of standardized assay techniques such as simple colorimetric, High-performance liquid chromatography (HPLC) and Nuclear magnetic resonance (NMR) spectroscopy. Furthermore this research has practical uses in the biorefining of biomass substrates for second generation biofuels and novel biobased chemicals by allowing HTP SSF screening, which should allow selected samples to be scaled up or studied in more detail. [ABSTRACT FROM AUTHOR]

Biorefinery has emerged in recent years as an alternative to petrorefinery, as biofuels have all the potential to replace fossil fuels for the sustainable development of human society. From this aspect, lignocellulosic biomasses are the most important, since these are the most abundant ubiquitous most raw material on earth, which can be converted into biofuels such as bioethanol, biobutanol, biohydrogen, biogas, etc. There are several strategies for conversion, such as biochemical, thermochemical, and microbial conversions of biomasses to biofuels; however, each of the strategies has its own consequences. Enzymatic conversion of biomasses into sugars, and thereby into bioethanol, is considered as the most sustainable way. However, biomass recalcitrance to enzymatic hydrolysis is the biggest challenge, as cellulose, hemicellulose, and lignin are intricately attached to each other making their separation a tedious task. Pretreatment is necessary to partially remove or change the form of lignin to make cellulose and hemicellulose accessible to enzymes. Most of the pretreatment methods are designed to target lignin, as it is the major component responsible for recalcitrance nature of biomasses. Laccase is a versatile lignin-degrading or lignin-modifying enzyme which is secreted by filamentous fungi and bacteria, and is reported for the biological pretreatment of biomasses, which is the most sustainable way of pretreatment. However, the rate of the reaction is extremely slow making it less attractive. This article will give an insight into the biorefinery of biomasses, with the special significance to laccase. [ABSTRACT FROM AUTHOR]

In the future liquid biofuels will need to be renewable, sustainable, as well as technically and economically viable. This paper provides an overview of the challenges that the biochemical production of cellulosic ethanol process still faces. The main emphasis of the paper is on challenges that emerge from the scale of liquid biofuel production. These challenges include raw material availability, other consumables, and side stream handling. The pretreatment, C5 fermentation, and concentration of sugars in processing need improvements, too. Sustainability issues and greenhouse gas reduction also pose a challenge for implementation and require development of internationally recognized sustainability principles and standards, and certification of sustainable operation. Economics of cellulosic ethanol processes are still also an area under development and debate. Yet, the Energy Independence and Security Act mandate together with the European Union Renewable Energy Directive and other local targets are driving the development and implementation forward towards more significant contribution of biofuels in the transportation sector. [ABSTRACT FROM AUTHOR]

The production of biofuels from agricultural biomass has attracted much attention from researchers in recent years. Biomass residues generated from agricultural production of corn and barley represent an essential source of raw material for the production of biofuels, and a mathematical programming-based approach can be used to establish an efficient supply chain. This paper proposes a model of mixed-integer linear programming (MILP) that seeks to minimize the total cost of the bioethanol supply chain. The proposal allows determining the optimal number and location of storage centers, biorefineries, and mixing plants, as well as the flow of biomass and bioethanol between the facilities. To show the proposed approach, we present a case study developed in the region of Tulancingo, Hidalgo, in Mexico (case study), considering the potential of biomass (corn and barley residues) in the region. The results show the costs for the production of bioethanol, transportation, and refining and total cost of the bioethanol supply chain, besides a sensitivity analysis on the costs of the bioethanol supply chain which is presented by mixing different percentages of bioethanol with fossil fuel to satisfy the demand. We conclude that the proposed approach is viable in the process of configuring the supply chain within the proposed study region. [ABSTRACT FROM AUTHOR]

This paper presents an economic optimization of a supply chain network to produce sugar and bioethanol from the first- and second-generation biomass in South Africa. A mixed-integer linear program model in combination with Google Earth® and ArcGIS was hereby developed to account for sugar demand, different feedstocks and products, as well as their distribution, tax subsidies and different processing technologies to address bioethanol production. The model was applied to two case studies depending on availability of biomass of which the results showed that the integrated bioethanol and sugar supply chain network is economically viable in South Africa. Transportation costs accounted for a significant part of the costs incurred in the supply chain, while highest profits are made when higher amounts of raw materials are available and there is no restriction relating to ethanol production. It is concluded that the 2% bioethanol-fuel blend target stipulated by the government of South Africa in the biofuel industrial strategy can be exceeded while still producing current amounts of sugar. [ABSTRACT FROM AUTHOR]

Simultaneous saccharification and fermentation (SSF) of solid biomass can reduce the complexity and improve the economics of lignocellulosic ethanol production by consolidating process steps and reducing end-product inhibition of enzymes compared with separate hydrolysis and fermentation (SHF). However, a longstanding limitation of SSF has been too low ethanol yields at the high-solids loading of biomass needed during fermentation to realize sufficiently high ethanol titers favorable for more economical ethanol recovery. Here, we illustrate how competing factors that limit ethanol yields during high-solids fermentations are overcome by integrating newly developed cosolvent-enhanced lignocellulosic fractionation (CELF) pretreatment with SSF. First, fed-batch glucose fermentations by Saccharomyces cerevisiae D5A revealed that this strain, which has been favored for SSF, can produce ethanol at titers of up to 86 g.L-1. Then, optimizing SSF of CELF-pretreated corn stover achieved unprecedented ethanol titers of 79.2, 81.3 and 85.6 g.L-1 in batch shake flask, corresponding to ethanol yields of 90.5%, 86.1% and 80.8% at solids loadings of 20.0 wt %, 21.5 wt % and 23.0 wt %, respectively. Ethanol yields remained at over 90% despite reducing enzyme loading to only 10 mg protein.g glucan-1 [∼6.5 filter paper units (FPU)], revealing that the enduring factors limiting further ethanol production were reduced cell viability and glucose uptake by D5A and not loss of enzyme activity or mixing issues, thereby demonstrating an SSF-based process that was limited by a strain's metabolic capabilities and tolerance to ethanol. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the influence of thermocompression conditions on lignocellulosic biomasses such as sugarcane bagasse (SCB) in the production of 100% binderless bio-based materials. Five parameters were investigated: pressure applied (7–102 MPa), molding temperature (60–240 °C), molding time (5–30 min), fiber/fine-particle ratio (0/100–100/0) and moisture content (0–20%). These parameters affected the properties and chemical composition of the materials. The density ranged from 1198 to 1507 kg/m3, the flexural modulus from 0.9 to 6.9 GPa and the flexural strength at breaking point from 6.1 to 43.6 MPa. Water absorption (WA) and thickness swelling (TS) values ranged from 21% to 240% and from 9% to 208%, respectively. Higher mechanical properties were obtained using SCB with fine particles, low moisture content (4–10%) and high temperature (≥200 °C) and pressure (≥68 MPa), while water resistance was improved using more severe thermocompression conditions with the highest temperature (240 °C) and time (30 min) or a higher moisture content (≥12.5%). Correlations were noted between the mechanical properties and density, and the material obtained with only fine particles had the highest mechanical properties and density. Material obtained with a 30 min molding time had the lowest WA and TS due to internal chemical reorganization followed by hemicellulose hydrolysis into water-soluble extractables. [ABSTRACT FROM AUTHOR]

Biofuels are clean and renewable energy resources gaining increased attention as a potential replacement for non-renewable petroleum-based fuels. They are derived from biomass that could either be animal-based or belong to any of the three generations of plant biomass (agricultural crops, lignocellulosic materials, or algae). Over 130 studies including experimental research, case studies, literature reviews, and website publications related to bioethanol production were evaluated; different methods and techniques have been tested by scientists and researchers in this field, and the most optimal conditions have been adopted for the generation of biofuels from biomass. This has ultimately led to a subsequent scale-up of procedures and the establishment of pilot, demo, and large-scale plants/biorefineries in some regions of the world. Nevertheless, there are still challenges associated with the production of bioethanol from lignocellulosic biomass, such as recalcitrance of the cell wall, multiple pretreatment steps, prolonged hydrolysis time, degradation product formation, cost, etc., which have impeded the implementation of its large-scale production, which needs to be addressed. This review gives an overview of biomass and bioenergy, the structure and composition of lignocellulosic biomass, biofuel classification, bioethanol as an energy source, bioethanol production processes, different pretreatment and hydrolysis techniques, inhibitory product formation, fermentation strategies/process, the microorganisms used for fermentation, distillation, legislation in support of advanced biofuel, and industrial projects on advanced bioethanol. The ultimate objective is still to find the best conditions and technology possible to sustainably and inexpensively produce a high bioethanol yield. [ABSTRACT FROM AUTHOR]

Biofuel, an inexhaustible fuel source, plays a pivotal role in the contemporary era by diminishing the dependence on non-renewable energy sources and facilitating the mitigation of CO2 emissions. Due to the many constraints in existing technology and the resulting increased costs, the production of biofuels on a large scale is a laborious process. Furthermore, the methods used to convert varied feedstock into the intended biofuel may vary based on the specific techniques and materials involved. The demand for bioethanol is increasing worldwide due to the implementation of regulations by world nations that mandates the blending of bioethanol with petrol. In this regard, second-generation bioethanol made from lignocellulosic biomass is emerging at a rapid rate. Pre-treatment, hydrolysis, and fermentation are some of the technical, practical, and economic hurdles that the biochemical conversion method must overcome. Nanoparticles (NPs) provide a very effective approach to address the present obstacles in using biomass, due to their selectivity, energy efficiency, and time management capabilities, while also reducing costs. NPs smaller dimensions allow them to be more effective at interacting with lignocellulosic components at low concentrations to release carbohydrates that can be utilized to produce bioethanol. This article provides a concise overview of various biofuels and the nanotechnological advancements in producing it, with a particular emphasis on ethanol. It provides a detailed discussion on the application of nanotechnology at each stage of ethanol production, with a particular emphasis on understanding the mechanism of how nanoparticles interact with lignocellulose. [ABSTRACT FROM AUTHOR]

Lignocellulosic material is the most promising feedstock for the bioethanol production however, due to complicated physico-chemical characteristics of biomasses, it is necessary to pretreat the biomass before the bioethanol production. The goal of the pretreatment is to open the biomass structure for enzymatic hydrolysis to gain higher sugar and ethanol yields in further processes. In this paper a novel explosive decompression pretreatment is studied where two gases -- nitrogen and compressed air are utilized for pressure generation. For this, traditional three-step bioethanol production process was used, where explosive decompression pretreatment with N2 gas or compressed air was applied for biomass pretreatment. Glucose and ethanol concentrations were measured during the process. Glucose and ethanol yields and process efficiencies were used to evaluate the effect of explosive decompression pretreatment and its suitability for biomass pretreatment in bioethanol production process. Results show that the highest glucose yield was gained when nitrogen gas was used, while difference in glucose yield compared to that of autohydrolysis was negligible when compressed air was applied. [ABSTRACT FROM AUTHOR]

Currently, valorization of lignocellulosic biomass almost exclusively focuses on the production of pulp, paper, and bioethanol from its holocellulose constituent, while the remaining lignin part that comprises the highest carbon content, is burned and treated as waste. Lignin has a complex structure built up from propylphenolic subunits; therefore, its valorization to value-added products (aromatics, phenolics, biogasoline, etc.) is highly desirable. However, during the pulping processes, the original structure of native lignin changes to technical lignin. Due to this extensive structural modification, involving the cleavage of the β-O-4 moieties and the formation of recalcitrant C-C bonds, its catalytic depolymerization requires harsh reaction conditions. In order to apply mild conditions and to gain fewer and uniform products, a new strategy has emerged in the past few years, named 'lignin-first' or 'reductive catalytic fractionation' (RCF). This signifies lignin disassembly prior to carbohydrate valorization. The aim of the present work is to follow historically, year-by-year, the development of 'lignin-first' approach. A compact summary of reached achievements, future perspectives and remaining challenges is also given at the end of the review. [ABSTRACT FROM AUTHOR]

Biofuels are the sustainable counterparts of fossil fuels to meet the increasing energy demands of the current and future generations. Biofuels are produced from waste organic residues with the application of mechanical, thermochemical and biological methods and processes. While mechanical and thermochemical conversion processes involve the use of heat, pressure, catalysts and other physicochemical attributes for the direct conversion of biomass, biological conversion requires microorganisms and their enzymes as biocatalysts to degrade the fermentable substrates into biofuels and biochemicals. This article highlights the advances and opportunities in biological conversion technologies for the development of a closed-loop biorefinery approach. This review highlights the distinction between biological and thermochemical conversion technologies, including a discussion on the pros and cons of the pathways. Different categories of biological conversion processes, such as enzymatic saccharification, submerged fermentation, solid-state fermentation and simultaneous saccharification and fermentation are also discussed in this article. The main essence of this article is the description of different fermentative technologies to produce next-generation biofuels, such as bioethanol, biobutanol, biomethane, biohydrogen and biodiesel. This article provides a state-of-the-art review of the literature and a technical perspective on the bioproduction of bioethanol, acetone–ethanol–butanol fermentation, anaerobic digestion, photo/dark fermentation, and the transesterification of lignocellulosic substrates to produce the above-mentioned biofuels. In addition, recommendations for improving bioprocessing efficiency and biofuel yields are provided in this comprehensive article. [ABSTRACT FROM AUTHOR]

Bamboo has been identified as a promising solution to the energy crisis and climate change as a source of biomass energy. Due to its rapid growth and high‐value products, bamboo is considered as a potential source of biomass energy. Bamboo contains a significant amount of cellulose and hemicellulose, which can be converted to sugar constituents, making it an ideal raw material for energy production. This article reviews the different processes of producing bioethanol, biogas, biochar, and bio‐oil from bamboo biomass using techniques such as pyrolysis, hydrothermal liquefaction, fermentation, and anaerobic digestion, and discusses the opportunities and challenges of these conversion technologies. It also reviews the main types and morphological characteristics of energy bamboo species and proposes an evaluation system for energy bamboo species, which optimizes the utilization efficiency of bamboo biomass energy and maximizes benefits by adopting appropriate methods for producing bioenergy based on the characteristics of different bamboo species. [ABSTRACT FROM AUTHOR]

Overuse of non-renewable fossil fuels due to the population explosion urges us to focus on renewable fuels such as bioethanol. It is a well-known fact that ethanol is useful as a blending product with common fuels such as petrol and diesel. This reduces the cost besides bringing down environmental pollution. Apart from chemical methods, bioethanol is generated from photosynthetic plants including algae, plant-based products, microbial organisms and their waste. Specifically, the production of ethanol from microalgal sources has been an attractive method in recent days. The reason behind using microalgal species is their simple structure with photosynthetic ability. In contrast, certain algal species often go disused in some regions. Hence, the production of ethanol from algal sources is one of the best waste management practices. Moreover, it is easy to improve the biomass in microalgal species by altering the physicochemical conditions such as light, pH, temperature, external supply of nutrients, vitamins, nano-sized particles, gene alterations etc., which will enhance ethanol production. In this review, the methods used for ethanol production are discussed. In addition, the factors involved in algal growth and ethanol production are emphasized. Overall, this review focuses on ethanol production from various algal species. This information will be useful for industrial-level production of ethanol and future renewable energy research. [ABSTRACT FROM AUTHOR]

The current energy scenario and policies demand the transition of the fuel economy from conventional fossil fuels to renewable fuels, carbon-neutral fuels, and/or decarbonized fuels. The impact of biomass-derived fuels is well-known as their radiocarbon dating indicates their contribution to young carbon emissions in addition to fewer emissions of particulates, sulfur dioxide, and air pollutants compared to fossil fuels. The various kinds of biomass available in India are already being established as potential sources for the production of biofuels and power generation. In this context, besides the quantity of biomass, environmental and economic factors are critically important for determining the range of conversion processes. Currently in India, agricultural-based biomass is the major partner for bioenergy generation. The annual surplus of agriculture-based biomass from major crops, available after its utilization for domestic use, cattle feeding, compost fertilizer, etc., is about 230 million metric tons (MMT). The estimated gross biomass power potential (based on trends) for 2019–2020 from the selected crops is around 30,319.00 Megawatt electric (MWe) at the pan-India level. However, it can be as high as 50,000 MWe after expanding the scope of available biomass from different energy sources. Moreover, the increasing trend of the country for the production of municipal solid waste (MSW) at a rate of 0.16 million tons (Mt) per day also indicates its potential for bioenergy generation. Nevertheless, its decentralized collection and segregation are key issues to its availability for bioenergy conversion/power generation. Therefore, the need of this hour is an effective utilization strategy plan for every type of available biomass including biomass-based refineries, renewable energy carriers, and/or other value-added products. This review aims to compile the various biomass resources (agricultural residues, municipal solid waste, forest-based biomass, industry-based biomass, and aquatic biomass) available in India and their potential for the generation of bioenergy (CBG, bioethanol, power, co-generation, etc.) through various bioconversion technologies that are available/in progress in the country. It also summarizes the current bioenergy scenario of India and initiatives taken by the Indian Government to achieve its future demand through biomass to energy conversion. [ABSTRACT FROM AUTHOR]

This paper evaluates the optimal composition of annual and perennial biomass feedstocks for a biorefinery. A generic optimization model is built to minimize costs - harvest, transport, storage, seasonal, and environmental costs - subject to various constraints on land availability, feedstock availability, processing capacity, contract terms, and storage losses. The model results are demonstrated through a case study for a midwestern U.S. location, focusing on bioethanol as the likely product. The results suggest that high-yielding energy crops feature prominently (70 to 80%) in the feedstock mix in spite of the higher establishment costs. The cost of biomass ranges from 0.16 to 0.20 $ l-1 (US$ 0.60 to $0.75 per gallon) of biofuel. The harvest shed shows that high-yielding energy crops are preferably grown in fields closer to the biorefinery. Lowyielding agricultural residues primarily serve as a buffer crop to meet the shortfall in biomass requirement. For the case study parameters, the model results estimated a price premium for energy crops (2 to 4 $ t-1 within a 16 km (10-mile) radius) and agricultural residues (5 to 17 $ t-1 in a 16 to 20 km (10 to 20 mile) radius. [ABSTRACT FROM AUTHOR]

Background: Sweet sorghum is a domesticated grass containing a sugar-rich juice that can be readily utilized for ethanol production. Most of the sugar is stored inside the cells of the stalk tissue and can be difficult to release, a necessary step before conventional fermentation. While this crop holds much promise as an arid land sugar source for biofuel production, a number of challenges must be overcome. One lies in the inherent labile nature of the sugars in the stalks leading to a short usable storage time. Also, collection of sugars from the sweet sorghum stalks is usually accomplished by mechanical squeezing, but generally does not collect all of the available sugars. Results: In this paper, we present two methods that address these challenges for utilization of sweet sorghum for biofuel production. The first method demonstrates a means to store sweet sorghum stalks in the field under semi-arid conditions. The second provides an efficient water extraction method that can collect as much of the available sugar as feasible. Operating parameters investigated include temperature, stalk size, and solid-liquid ratio that impact both the rate of sugar release and the maximal amount recovered with a goal of low water use. The most desirable conditions include 30°C, 0.6 ratio of solid to liquid (w/w), which collects 90 % of the available sugar. Variations in extraction methods did not alter the efficiency of the eventual ethanol fermentation. Conclusions: The water extraction method has the potential to be used for sugar extraction from both fresh sweet sorghum stalks and dried ones. When combined with current sugar extraction methods, the overall ethanol production efficiency would increase compared to current field practices. [ABSTRACT FROM AUTHOR]

Abstract: One of the largest potential feedstock for ethanol is lignocellulosic biomass, principally agricultural residues. Cellulosic ethanol can be made from the stems, leaves, bagasse, stalks and trunks of plants which are not used for human-food production. However, there are significant economic challenges facing the second generation of biofuels. Consequently, application of process engineering is necessary to improve the overall process efficiency. Therefore, the main objective of this paper is to apply energy and exergetic analysis together with process integration methodologies coupled with process simulation as a unified and effective tool for the evaluation of converting lignocellulosic biomass to ethanol. In this paper, bioethanol production from acid-pretreated bagasse using different process configurations that include sequential hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and simultaneous saccharification and co-fermentation (SSCF) were analyzed. [Copyright &y& Elsevier]

Abstract: Global threats of fuel shortages in the near future and climate change due to green-house gas emissions are posing serious challenges and hence and it is imperative to explore means for sustainable ways of averting the consequences. The dual application of microalgae for phycoremediation and biomass production for sustainable biofuels production is a feasible option. The use of high rate algal ponds (HRAPs) for nutrient removal has been in existence for some decades though the technology has not been fully harnessed for wastewater treatment. Therefore this paper discusses current knowledge regarding wastewater treatment using HRAPs and microalgal biomass production techniques using wastewater streams. The biomass harvesting methods and lipid extraction protocols are discussed in detail. Finally the paper discusses biodiesel production via transesterification of the lipids and other biofuels such as biomethane and bioethanol which are described using the biorefinery approach. [Copyright &y& Elsevier]

The wide-spread dependence of transportation sector on the ever-depleting and greenhouse gas emitting fossil fuels when burnt has raised considerable energy security and environmental concerns. Consequently, countries around the world have positioned biofuels as a center stage alternative to fossil fuels in their national policies to provide energy security and carbon emission control. In this regard, the paper conducts a feasibility assessment of setting-up large-scale supply chain of bioethanol (i.e., a biofuel variant) based on the regional availability of agricultural residues. Critical resources and capabilities requirements and governance attributes for bioethanol supply chains are explored using the resource-based view and institutional theory lenses. An agricultural residues (as biomass inputs) based bioethanol supply chain (BESC) model is proposed to incorporate the economic and environmental optimality considerations for an agro-climatic region. A case study of the Punjab State in India is used as an application of the proposed BESC model. Findings suggest that sustainable BESC configurations can be achieved differently for different agricultural residues. Comparative analyses, trade-off scenarios, and sustainability assessments of various agricultural residues-based BESC configurations are conducted. The policy implications of the priority areas are discussed within the bounds of India's biofuel policy. • Designed biomass-based bioethanol supply chains from a policy perspective. • Resource-based view and institutional theory are applied. • Developed large-scale supply chain model for energy security and carbon-neutrality. • Performed comparative, trade-off, and sustainability analyses for biomass types. • Priority areas for creating a nationwide bioethanol economy are identified. [ABSTRACT FROM AUTHOR]

Flax is one of the few plants that are entirely a source of raw materials for further production. Promising directions for the use of flax biomass may be the production of bioenergy in the form of 2G biofuels and the production of "green" composites. The aim of the study is to compare the biomass of fiber flax, linseed and dual-purpose varieties of cultivated flax (Linum usitatissimum L.) susceptibility to the biorefining processes. In the first stage of the research, based on the results of yield structure features and biometric measurements of plants, the most optimal flax line was selected for the fiber flax, linseed and dual purpose. Next, the forms of flax were pretreated with sodium hydroxide (NaOH), the chemical composition was determined and SEM images were taken. The obtaining of bioethanol process SFF (simultaneous saccharification and fermentation) was carried out. In addition, biodegradable polymers were modified with flax biomass, shapes were prepared, and the rheological and mechanical properties, as well as microbiological activity of biocomposites, were determined. The highest concentration of ethanol (8.72 g·L−1) and the greatest susceptibility to mold fungi of the biocomposites were obtained for the fiber flax variety PET 16/20. [ABSTRACT FROM AUTHOR]

As greenhouse gas emissions are continuously increasing, research is now privileging greener and more sustainable human activities. An attractive strategy in the pursuit of sustainability is the valorization of lignocellulosic biomasses for the production of bioethanol. This approach relies on the bioconversion of wood and agricultural waste, which are abundant globally. They represent considerable sources of fermentable sugars that can be recovered through enzymatic hydrolysis. However, the presence of lignin in wood waste makes it more recalcitrant to enzymatic hydrolysis, and reduces the efficiency of the bioconversion process. Therefore, a pretreatment preceding hydrolysis is highly necessary in order to disrupt the resistant structure of woody biomass. The type and severity of the pretreatment affect the outcomes of the hydrolysis and fermentation steps, just as they strongly influence the overall process costs. Given this context, bioenergy production from this biomass is a promising alternative method of sustainably responding to energy demands while reducing the amounts of waste left in nature. The aim of this review is to thoroughly compare the recent bioconversion processes performed on woody substrates over the past five years, with a focus on thermomechanical pretreatments. Moreover, this review will discuss the outcomes of their separate steps, their impact on the overall process, and their energetic aspects. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass resource has been widely used as a natural resource for the synthesis of biofuels and bio-based products through pre-treatment, saccharification and fermentation processes. In this review, we delve into the environmental implications of bioethanol production from the widely utilized lignocellulosic biomass resource. The focus of our study is the critical stage of pre-treatment in the synthesis process, which also includes saccharification and fermentation. By collecting scientific data from the available literature, we conducted a comprehensive life cycle analysis. Our findings revealed substantial differences in the environmental burdens associated with diverse pre-treatment methods used for lignocellulosic biomass. These results highlight the importance of selecting environmentally benign pre-treatment techniques to promote the sustainability of bioethanol production. Future research directions are suggested, emphasizing the optimization of pre-treatment processes to further mitigate their environmental impact. [ABSTRACT FROM AUTHOR]

The sugar beet processing in the sugar production industry releases huge amounts of sugar beet pulp, lime residue, and molasses, which can be considered a valuable by-product as a source of cellulose, hemicellulose, and pectin. Sugar beet pulp is often used as a high-energy, low-protein supplement for ruminants to promote optimal rumen health and increase milk production. However, it cannot be used in large quantities and is thrown away, causing environmental pollution. Valorizing sugar beet processing wastes via biotechnological approaches into valueadded products is cost-effective and eco-friendly. In this article, recent developments in the biotechnological valorization of sugar beet byproducts to produce biofuels, bioethanol, butanol, biomass and platform chemicals such as gluconic acid, lactic acid, rhamnolipid biosurfactant, and endo-polygalacturonase were reviewed, and the methods provide a way to save the environment. Several sugar beet processing plants in the Kyrgyz Republic can offer these methods as a roadmap for value-added production. [ABSTRACT FROM AUTHOR]

Biomass is an abundant resource for energy production and it has gained attention as a mainstream option to meet increasing energy demands. Pyrolysis has been one of the most prevalent thermochemical processes for biomass conversion. In the pyrolysis process, the biomass decomposes into three byproducts: bio-oil (60–75%), biochar (15–25%), and syngas (10–20%), depending on the feedstock and its composition. The energy required to convert the biomass varies depending on the levels of cellulose, hemicellulose, and lignin. This work proposes a novel two-stage stochastic model that designs an efficient biomass supply chain mindful of the trade-offs between pyrolysis byproducts (bioethanol and biochar). Remarkably, the model integrates biomass quality-related costs associated with moisture and ash content such as the energy consumption of preprocessing equipment and boiler maintenance due to excess ash. Biomass quality directly affects the production yield as well as the total cost of production and distribution. The results from our case study indicate a shortage of biomass from the suppliers to fulfill the demand for biochar from the power plants and bioethanol from the cities. Furthermore, the bioethanol price has the most impact on the total supply chain according to our sensitivity analysis. [ABSTRACT FROM AUTHOR]

36290525 6 Gundupalli M.P., Chuetor S., Cheenkachorn K., Rattanaporn K., Show P.L., Cheng Y.S., Sriariyanun M. Interferences of Waxes on Enzymatic Saccharification and Ethanol Production from Lignocellulose Biomass. Microorganisms like bacteria and yeasts are widely used in the fermentation for bioethanol production, which plays a critical role in biomass waste utilisation. For example, biomass wastes could be used to serve as alternative feedstocks, providing green and sustainable biofuels such as bioethanol, biogas, and biodiesel [[2]]. Although the rapid development of industrialisation has brought great benefits to our societies, waste accumulation and energy depletion have inevitably grown to be critical issues in recent decades. [Extracted from the article]

Softwood biomass is an attractive renewable feedstock for bioethanol production. The net energy yield of the related biorefinery processes has been limited, however, by its high lignin content, which is recalcitrant to hydrolysis and fermentation. New understanding of the causes of the inhibiting effects is critical to approach the optimal energy/water nexus in a biorefinery. This paper introduces a new prehydrolysis simultaneous saccharification and fermentation process to convert sulfite pretreated Monterey pine into bioethanol, resulting in an extremely high titer of 82.6 g/L or 10 vol%. The new process was carried out at a solid content of 25% by using a commercial enzyme and Saccharomyces cerevisiae . Sugars in the pretreatment spent liquor were concentrated and mixed into the fermentation broth for complete utilization of the sugars, but it was found that this liquor can also affect the ethanol titer during fermentation. Control experiments suggested that sugar-based pretreatment by-products were not the major contributors to the inhibition, while small molecular weight compounds played a major role in affecting the fermentability of the slurry under high temperature. Cell viability tests showed that reducing fermentation temperature from 35 °C to 28 °C can overcome the impacts of pretreatment by-products on cell growth and ethanol production. Without the need of detoxification, the resulting ethanol titer is approaching the theoretical yield and is currently among the highest in softwood conversion. The net energy yield of the new process was 2410 MJ per ton oven-dried wood, which is approximately 730–1690 MJ higher than that of the other biorefinery processes. The water input before reclamation was 3.65 tons per ton dried wood, which is 25.8–51.2% lower than most of the other processes. [ABSTRACT FROM AUTHOR]

Polyethylene (PE) and polypropylene (PP) can be synthesized from biomass through dehydration, dimerization, and metathesis reactions from ethanol or methanol-to-olefin reaction of synthesis gas. This paper examines the socioeconomic aspects of such biomass-derived resin production, which are composed of environmental impacts quantified by life cycle analysis (LCA) and the structure of generated value flows specified by structural path analysis (SPA) based on a Japanese input–output table. Missing inventory data were estimated by process simulation using Aspen Plus™ and Aspen HYSYS™ with design information extracted from the literature, patents, and design heuristics. LCA based on actual and demonstration plants with process simulation shows the environmental advantage of biomass-derived resins on greenhouse gas (GHG) emissions reduction. PE production has the largest effect on GHG emissions reduction, followed by bioethanol from a gasoline mixture, and PP. The uncertainties in agricultural processes also influence the potential application of international and domestic bioethanol production and synthesis gas obtained from the gasification of waste woods. According to SPA results for gasoline, PE, PP, and plastic products, the cyclicality of resins and plastic products, which was quantitatively analyzed as the total cyclic cash flows from target products to final demands, is much larger than that of gasoline. Based on these results, biomass-derived resin production has the potential to increase added values in an economy, with a corresponding decrease in GHG emissions. [ABSTRACT FROM AUTHOR]

Ethanol made from cellulosic biomass is an alternative to petroleum-based liquid transportation fuels. However, large-scale manufacturing of cellulosic ethanol is hindered by several factors. The main factor driving this hindrance is the low density of cellulosic biomass. Ultrasonic vibration-assisted pelleting can effectively increase cellulosic biomass density by compressing raw biomass into pellets, reducing transportation and storage costs. Pelleting temperature has also been identified as a key parameter influencing pellet quality. In this paper, a predictive mathematical model of pelleting temperature using spatio-temporal dynamics was developed to study multiple factors affecting temperature rise through pelleting. The mathematical model was then validated with experimental data along with high goodness of fit (average R 2 > 0.83 ). Effects of three input variables (ultrasonic power, pelleting pressure, and pellet weight) on temperature ranges (highest temperature point and lowest temperature point) were investigated using a 2 3 (two levels and three variables) factorial design. Our results indicated that friction between mold and biomass has a marginal effect on the temperature profiles, and demonstrated the highest and lowest temperature points are significantly correlated to the input variables (ultrasonic power, pellet weight, and pellet pressure) and their interaction effects. The proposed mathematical model delivers a new guideline by avoiding unnecessary experiments and provides a systematic understanding of temperature profiles during the biomass pelleting process. Knowledge transferred from the current study fulfills the literature gap between mathematical modeling research and an optimal, ultrasonic, vibration-assisted pelleting process; and, therefore, provides insight into improving biomass quality in energy-related ultrasonic manufacturing. [ABSTRACT FROM AUTHOR]

The depletion of fossil fuel resources requires a greater emphasis on the development of renewable energy technologies. Ethanol produced via biochemical means is a renewable liquid fuel option that shows great promise. In this paper, the large scale production of ethanol via a method of converting lignocellulosic material without the need for enzyme hydrolysis, termed consolidated bioprocessing (CBP), is analyzed and compared to traditional separate hydrolysis and fermentation (SHF) methods to determine the profitability of biochemical ethanol production. Optimal process topologies for both the CBP and SHF technologies are selected from superstructures considering multiple biomass feeds, chosen from those available across the United States, and multiple prospective pretreatment technologies. Steam cogeneration is also considered to produce the necessary hot utilities as well as electricity as a salable byproduct. Results show the optimal consolidated bioprocessing plant produces about 66 million gallons of ethanol to be sold at a breakeven price of $1.31 per gallon ($0.35 per liter) from a pure sugarcane bagasse feed and sodium hydroxide pretreatment method in addition to 67 MW of electricity per year. These results compare favorably to SHF production methods, showing a 20% decrease in the minimum ethanol selling price (MESP) and 197.5% increase in electricity generation despite a 13.3% drop in ethanol production. A long term economic evaluation is performed to determine an attractively profitable selling price for the ethanol produced. Additional analysis is done on the effect of a mixed biomass feed on process profitability and impact on biomass harvesting radius. [ABSTRACT FROM AUTHOR]

A wide range of inorganic and organic chemicals are used during the pretreatment and enzymatic hydrolysis of lignocellulosic biomass to produce biofuels. Developing an industrially relevant 2G biorefinery process using such chemicals is challenging and requires more unit operations for downstream processing. A sustainable process has been developed to achieve industrially relevant titers of bioethanol with significant ethanol yield. The pretreatment of sorghum biomass was performed by a continuous pilot-scale hydrothermal reactor followed by disk milling. Enzymatic hydrolysis was performed without washing the pretreated biomass. Moreover, citrate buffer strength was reduced to 100-fold (50 mM to 0.5 mM) during the enzymatic hydrolysis. Enzymatic hydrolysis at 0.5 mM citrate buffer strength showed that significant sugar concentrations of 222 ± 2.3 to 241 ± 2.3 g/L (glucose + xylose) were attained at higher solids loadings of 50 to 60% (w/v). Furthermore, hydrolysates were fermented to produce bioethanol using two different xylose-fermenting Saccharomyces cerevisiae strains and a co-culture of xylose-fermenting and non-GMO yeast cultures. Bioethanol titer of 81.7 g/L was achieved with an ethanol yield of 0.48 gp/gs. Additionally, lipids were produced using the oleaginous yeast Rhodosporidium toruloides, yielding 13.2 g/L lipids with cellular lipid accumulation of 38.5% w/w from 100 g/L of sugar concentration. In summary, reducing the strength of the citrate buffer during enzymatic hydrolysis and omitting inorganic chemicals from the pretreatment process enhances the fermentability of hydrolysates and can also reduce operating costs. [ABSTRACT FROM AUTHOR]

A framework for assessing, from a sustainability and circular bioeconomy point of view, the best valorization approach for biorefineries side-streams has been developed and validated. Two biorefinery side streams are considered as case-studies for validation: rapeseed meal from biodiesel and corn oil from bioethanol production. Firstly, a methodology to evaluate different valorization scenarios has been developed following a holistic approach that addresses technical aspects, environmental impact, and economic analysis. This way, a framework (inspired by the Battelle Method and using insights from Multicriteria Decision Analysis) has been produced where the sustainability potential of each scenario can be assessed. Such framework has been validated for five valorization scenarios for rapeseed meal and seven scenarios for corn oil. It can be concluded that protein extraction through alkaline (NaOH) hydrolysis is the best approach for rapeseed meal valorization while carotenoids recovery through ion exchange extraction is the most suitable strategy for corn oil. Secondly, for the selected scenarios, an estimation of the maximum recoverable amount of valuable compounds is conducted at the European and country-level. The use of this framework substantially aids in the best choice of the cutting-edge conversion technologies, supporting industry practitioners in the selection of processes to be further scaled-up. [ABSTRACT FROM AUTHOR]

Regarding the limited resources for fossil fuels and increasing global energy demands, greenhouse gas emissions, and climate change, there is a need to find alternative energy sources that are sustainable, environmentally friendly, renewable, and economically viable. In the last several decades, interest in second-generation bioethanol production from non-food lignocellulosic biomass in the form of organic residues rapidly increased because of its abundance, renewability, and low cost. Bioethanol production fits into the strategy of a circular economy and zero waste plans, and using ethanol as an alternative fuel gives the world economy a chance to become independent of the petrochemical industry, providing energy security and environmental safety. However, the conversion of biomass into ethanol is a challenging and multi-stage process because of the variation in the biochemical composition of biomass and the recalcitrance of lignin, the aromatic component of lignocellulose. Therefore, the commercial production of cellulosic ethanol has not yet become well-received commercially, being hampered by high research and production costs, and substantial effort is needed to make it more widespread and profitable. This review summarises the state of the art in bioethanol production from lignocellulosic biomass, highlights the most challenging steps of the process, including pretreatment stages required to fragment biomass components and further enzymatic hydrolysis and fermentation, presents the most recent technological advances to overcome the challenges and high costs, and discusses future perspectives of second-generation biorefineries. [ABSTRACT FROM AUTHOR]

Background: Woody plants provide the most abundant biomass resource that is convertible for biofuels. Since lignin is a crucial recalcitrant factor against lignocellulose hydrolysis, genetic engineering of lignin biosynthesis is considered as a promising solution. Many MYB transcription factors have been identified to involve in the regulation of cell wall formation or phenylpropanoid pathway. In a previous study, we identified that PtoMYB115 contributes to the regulation of proanthocyanidin pathway, however, little is known about its role in lignocellulose biosynthesis and biomass saccharification in poplar. Results: Here, we detected the changes of cell wall features and examined biomass enzymatic saccharification for bioethanol production under various chemical pretreatments in PtoMYB115 transgenic plants. We reported that PtoMYB115 might specifically regulate lignin biosynthesis to affect xylem development. Overexpression of PtoMYB115 altered lignin biosynthetic gene expression, resulting in reduced lignin deposition, raised S/G and beta-O-4 linkage, resulting in a significant reduction in cellulase adsorption with lignin and an increment in cellulose accessibility. These alterations consequently improved lignocellulose recalcitrance for significantly enhanced biomass saccharification and bioethanol yield in the PtoMYB115-OE transgenic lines. In contrast, the knockout of PtoMYB115 by CRISPR/Cas9 showed reduced woody utilization under various chemical pretreatments. Conclusions: This study shows that PtoMYB115 plays an important role in specifically regulating lignin biosynthesis and improving lignocellulose features. The enhanced biomass saccharification and bioethanol yield in the PtoMYB115- OE lines suggests that PtoMYB115 is a candidate gene for genetic modification to facilitate the utilization of biomass. [ABSTRACT FROM AUTHOR]

Renewable biofuels, such as biodiesel, bioethanol, and biobutanol, serve as long-term solutions to fossil fuel depletion. A sustainable approach feedstock for their production is plant biomass, which is degraded to sugars with the aid of microbes-derived enzymes, followed by microbial conversion of those sugars to biofuels. Considering their global demand, additional efforts have been made for their large-scale production, which is ultimately leading breakthrough research in biomass energy. Metagenomics is a powerful tool allowing for functional gene analysis and new enzyme discovery. Thus, the present article summarizes the revolutionary advances of metagenomics in the biofuel industry and enlightens the importance of unexplored habitats for novel gene or enzyme mining. Moreover, it also accentuates metagenomics potentials to explore uncultivable microbiomes as well as enzymes associated with them. [ABSTRACT FROM AUTHOR]

Olive oil industry is one of the most important industries in the world. Currently, the land devoted to olive-tree cultivation around the world is ca. 11 × 106 ha, which produces more than 20 × 106 t olives per year. Most of these olives are destined to the production of olive oils. The main by-products of the olive oil industry are olive-pruning debris, olive stones and different pomaces. In cultures with traditional and intensive typologies, one single ha of olive grove annually generates more than 5 t of these by-products. The disposal of these by-products in the field can led to environmental problems. Notwithstanding, these by-products (biomasses) have a huge potential as source of energy. The objective of this paper is to comprehensively review the latest advances focused on energy production from olive-pruning debris, olive stones and pomaces, including processes such as combustion, gasification and pyrolysis, and the production of biofuels such as bioethanol and biodiesel. Future research efforts required for biofuel production are also discussed. The future of the olive oil industry must move towards a greater interrelation between olive oil production, conservation of the environment and energy generation. [ABSTRACT FROM AUTHOR]

Developing effective, economical, and environmentally sound approaches for sewage sludge management remains an important global issue. In this paper, we propose a bioethanol-lignin (nonfood biomass)-based sewage sludge upgrading process for enhancing the heating value and reducing air pollutants of hybrid sewage sludge fuel (HSF) for the effective management of sewage sludge. Sewage sludge paste with the lignin-CaO solution implies drying at 105 °C accompanied by torrefaction at 250 °C. During torrefaction, moisture and partly volatile matter begin to evaporate, and are almost vaporized out to the surface. In this study, the proposed process enhances the net caloric value (NCV) to 37%. The lignin-embedded HSF shows a two-in-one combustion peak regardless of the mixing ratio, resulting in a 70% reduction of unburned carbon (UBC) emissions, which is one of the particular matter (PM) sources of combustion flue gas. Other air pollutants, such as CO, hydrocarbon, NOx, and SOx, were also reduced by the proposed process. In particular, SOx emission remained at ~1 ppm (average value) regardless of the sulfur content of the fuel. [ABSTRACT FROM AUTHOR]

For decades, lignocellulosic biomass has been introduced to the public as the most important raw material for the environmentally and economically sustainable production of high-valued bioproducts by microorganisms. However, due to the strong recalcitrant structure, the lignocellulosic materials have major limitations to obtain fermentable sugars for transformation into value-added products, e.g., bioethanol, biobutanol, biohydrogen, etc. In this review, we analyzed the recent trends in bioenergy production from pretreated lignocellulose, with special attention to the new strategies for overcoming pretreatment barriers. In addition, persistent challenges in developing for low-cost advanced processing technologies are also pointed out, illustrating new approaches to addressing the global energy crisis and climate change caused by the use of fossil fuels. The insights given in this study will enable a better understanding of current processes and facilitate further development on lignocellulosic bioenergy production. [ABSTRACT FROM AUTHOR]

In this study, we calculated the water footprint (WF) of second-generation bioethanol and hypothesized that second-generation bioethanol feedstock in response to the gradual depletion of fossil fuels has contributed to exorbitant international oil prices. To resolve these problems, countries worldwide have actively engaged in developing alternative energy plans to reduce their dependence on petroleum. Bioethanol is a critical choose items of biofuels, and increased use of biofuels for transportation is expected to substantially raise the level of competition for freshwater resources. In this paper, Taiwan's second-generation bioethanol demonstration plant is used as an example to calculate the WF of second-generation bioethanol. Using bagasse and rice straw as raw materials, the water footprint are 268.8 L H 2 O/L EtOH and 4674.9 L H 2 O/L EtOH, respectively, which is considerably lower than that of first-generation bioethanol. In this study, we proposed two sources of feedstock that are suitable for future second-generation bioethanol: (1) nonfood crop materials; and (2) domestic waste (e.g., food waste). The results of this study can be used by countries interested in using biofuels to formulate and implement energy policies that will enable them to develop renewable energy sources and simultaneously consider the management and application of water resources. [ABSTRACT FROM AUTHOR]

Background: Sugarcane (Saccharum spp.) covers vast areas of land (around 25 million ha worldwide), and its processing is already linked into infrastructure for producing bioethanol in many countries. This makes it an ideal candidate for improving composition of its residues (mostly cell walls), making them more suitable for cellulosic ethanol production. In this paper, we report an approach to improving saccharification of sugarcane straw by RNAi silencing of the recently discovered BAHD01 gene responsible for feruloylation of grass cell walls. Results: We identified six BAHD genes in the sugarcane genome (SacBAHDs) and generated five lines with substantially decreased SacBAHD01 expression. To find optimal conditions for determining saccharification of sugarcane straw, we tried multiple combinations of solvent and temperature pretreatment conditions, devising a predictive model for finding their effects on glucose release. Under optimal conditions, demonstrated by Organosolv pretreatment using 30% ethanol for 240 min, transgenic lines showed increases in saccharification efficiency of up to 24%. The three lines with improved saccharification efficiency had lower cell-wall ferulate content but unchanged monosaccharide and lignin compositions. Conclusions: The silencing of SacBAHD01 gene and subsequent decrease of cell-wall ferulate contents indicate a promising novel biotechnological approach for improving the suitability of sugarcane residues for cellulosic ethanol production. In addition, the Organosolv pretreatment of the genetically modified biomass and the optimal conditions for the enzymatic hydrolysis presented here might be incorporated in the sugarcane industry for bioethanol production. [ABSTRACT FROM AUTHOR]