Generation Biofuels Research Articles

Effects of molecular structure and active sites of 2,5-DMF and 2-MF on reaction characteristics during auto-ignition

2-methylfuran (2MF) and 2,5-dimethylfuran (2,5-DMF) are new generation of green biofuels, and because of their high octane number and similarity to gasoline in energy density, they are very potential octane boosters. However, the effect of molecular structure of furans on the knocking behavior of fuels is still unclear in the temperature range of 298 K–1198 K. Therefore, in this paper, the key free radicals and their reaction sites in the two fuel auto-ignition paths of 2MF and 2,5-DMF are studied in the range of low to intermediate temperature by DFT method. We found that DMF22j and 2MF22j produced by methyl dehydrogenation on the side chain of furan ring are the most stable radicals produced by H-abstraction reaction. For 2MFnOH, the reactivity of 2MF increased after OH addition and the addition reaction with O2 was most likely to occur when OH was bound to C2 site.

Industrial CO2 Capture by Algae: A Review and Recent Advances

The problem of global warming and the emission of greenhouse gases is already directly affecting the world’s energy. In the future, the impact of CO2 emissions on the world economy will constantly grow. In this paper, we review the available literature sources on the benefits of using algae cultivation for CO2 capture to decrease CO2 emission. CO2 emission accounts for about 77% of all greenhouse gases, and the calculation of greenhouse gas emissions is 56% of all CO2 imports. As a result of the study of various types of algae, it was concluded that Chlorella sp. is the best at capturing CO2. Various methods of cultivating microalgae were also considered and it was found that vertical tubular bioreactors are emerging. Moreover, for energy purposes, thermochemical methods for processing algae that absorb CO2 from flue gases were considered. Of all five types of thermochemical processes for producing synthesis gas, the most preferred method is the method of supercritical gasification of algae. In addition, attention is paid to the drying and flocculation of biofuels. Several different experiments were also reviewed on the use of flue gases through the cultivation of algae biomass. Based on this literature review, it can be concluded that microalgae are a third generation biofuel. With the absorption of greenhouse gases, the growth of microalgae cultures is accelerated. When a large mass of microalgae appears, it can be used for energy purposes. In the results, we present a plan for further studies of microalgae cultivation, a thermodynamic analysis of gasification and pyrolysis, and a comparison of the results with other biofuels and other algae cultures.

In vitro plant tissue culture as the fifth generation of bioenergy

Developing and applying a novel and sustainable energy crop is essential to reach an efficient and economically feasible technology for bioenergy production. In this study, plant tissue culture, also referred to as in vitro culture, is introduced as one of the most promising and environmentally friendly methods for the sustainable supply of biofuels. The current study investigates the potential of in vitro -grown industrial hemp calli obtained from leaf, root, and stem explants as a new generation of energy crop. For this purpose, the in vitro grown explants were first fully characterized in terms of elemental and chemical composition. Secondly, HTL experiments were designed by Design Expert 11 with a particular focus on biocrude. Finally, the chemical components, functional groups, and petroleum-like hydrocarbons present in the biocrude were identified by PY-GCMS. A 22.61 wt.% biocrude was produced for the sample grown through callogenesis of the leaf (CL). The obtained biocrude for CL consisted of 19.55% acids, 0.42% N compounds, 15.44% ketones, 16.03% aldehydes, 2.21% furans, 20.01% aromatics, 5.2% alcohols, and 19.88% hydrocarbons. To the best of the authors’ knowledge, this is the first report that in vitro -grown biomass is hydrothermally liquefied toward biocrude production; the current work paves the way for integrating plant tissue culture and thermochemical processes for the generation of biofuels and value-added chemicals.

A BRIEF REVIEW ON ALGAE BASED BIOFUEL

This Utilization of algae as a sustainable biofuel source is summarized in this critical assessment.Biohydrogen is a third-generation feedstock for the manufacture of biofuels(bioethanol, biodiesel,orbiogas)biofuel made from the gas cannot reach its maximum potential because of the higher Costs of farming,reaping, extraction other stages. Consequently, this evaluation grants Deriving biofuels starting from algaebiomass is explained in great detail systems such as raceway ponds and photobioreactors along with theirbottlenecks. Evolution of biofuel The first section of this manuscript addressed feedstock, from edibleoils to algae. Here are some insights into the various generation of biofuels. Ultimately, Algal cultivationpretreatments and future dimensions. These steps were explained in detail in order to makecarefully practical algal biofuel.

Algal biofuels: Technological perspective on cultivation, fuel extraction and engineering genetic pathway for enhancing productivity

Vast utilization and subsequent depletion of fossil fuels have forced to development of new approaches for finding a suitable alternative to fossil fuels. Algae remain a promising tool for producing third generation biofuels such as biodiesel, biohydrogen, bioethanol, etc and make them suitable material for bioenergy production. However, commercial application of biofuels from algal species is restricted due to cost for production, limitations in cultivation and harvesting and processing. This review focuses on various types of biofuels such as biodiesel, biohydrogen, bioethanol and biogas from different algal species utilizing cultivation systems such as raceway ponds and photobioreactors. The challenges in producing biofuels from native algal species are defined for finding alternative approach. This paper also focuses on the genetic engineering approaches available for modifying the pathway in algal species for increasing biomass and biofuel production. Metabolic activity can be enhanced using biochemical engineering. Hence the combined application of these approaches can help to take over the demerits of producing biofuels using algae. The cost required for biofuel production depends on the type of algal cultivating system and its challenge remains in harvesting and separation processes after cultivation.

Nanoparticles as stimulants for efficient generation of biofuels and renewables

Fossil fuels have caused irreversible damage to the ecosystem, and finding alternatives is critical to prevent futher degradation. To effectively tackle the fossil fuels dilemma, biofuels can encounter current energy demands by re-proposing existing biomass as feedstocks for biotransformation into various energy forms, such as bioethanol, biohydrogen. Because current methods cannot fully exploit the potential, the concept of using nanomaterials to accelerate the process was developed. Nanoparticles have a lot of potential for producing biofuels in a sustainable and commercially viable way. In the dark- and photo-fermentative organisms feed sugars and biowaste materials, the potential function of nanoparticles in enhancing bioethanol and biohydrogen generation has been investigated. The ability to use nano-supports in different subfields for biocatalysts might be a significant strategy for achieving the economic feasibility of several processes that are now being investigated, with minimal or no interference from nanosized particles in catalytic activity. Furthermore, nanocatalysts can be employed in different areas to chemically catalyze cellulose depolymerization or oil and fat transesterification with great efficiency. While there are hazards associated with every new technology, and the world is now far better positioned to analyze those risks and respond appropriately, it appears that the application of nanotechnologyto biofuels may be advanced without harming security, public health, or the environment.

Single-step integrated technology for enhanced CO2 biofixation and efficient lipid extraction in microalgal system including a water-immiscible solvent

The potential of microalgae for both carbon fixation and energy sustainability has been demonstrated. However, the low CO2 biofixation rate and high cost of lipid extraction restrict its large-scale development. This paper proposes a novel integrated technology for enhanced CO2 biofixation and efficient lipid extraction in microalgal system by adding water-immiscible solvent N-heptane over the culture medium. N-heptane can act as a ‘carbon sink’ and ‘extract agent’ without causing significant damage to microalgal cells. Specifically, N-heptane with the volume percentages of 4, 8, 12, 25 and 42 % was added to Chlorella sp. culture systems. Simulated flue gas containing 15 vol% CO2 in nitrogen gas was used as the sole carbon source. The maximum biomass concentration (0.84 g·L-1) and specific growth rate (0.23 d-1) were achieved with 12 % N-heptane. These values were higher than blank culture by 12.3 % (biomass concentration) and 56.9 % (specific growth rate). The CO2 biofixation rate increased with N-heptane to a maximum value of 220.2 mg·L-1·d-1, which was 64.7 % higher than that of the blank culture. Meanwhile, the system has a potential for the generation of biofuels with a maximum lipid amount of 2.82 g·gAlgae-1 in this single step approach.

Efficient utilization and management of seaweed biomass for biogas production

The global trend of seaweed production and their biomass utilization for biofuels generation is increased due to the high carbohydrate and protein content. Anaerobic digestion (AD) is a promising technology to convert organic compounds of seaweed biomass into biogas. However, a comprehensive review enclosing the biomethane potential, process parameters, microbial shifts, and effective approaches to enhance the digestibility and biogas production from seaweeds has not been reported. Thus, this article aims to explore, classify, and comprehensively present the potential of seaweeds for biogas production. The global trend of biofuels including biogas production from seaweed biomass is elucidated. The effect of seasonal variations on the biochemical composition of seaweeds is highlighted. The microbial community involved in AD of seaweeds is discussed. This article also covers the pretreatments, co-digestion, supplementation of additives, and sequential utilization of seaweeds to enhance biogas production. The seasonal variations significantly affected the composition of seaweeds and subsequently altered the content of inhibitory compounds. The application of different strategies (such as pretreatment) mitigated the effect of inhibitors and boosted biogas production. Firmicutes and Bacteroidetes were reported to be the major bacteria and Methanobacteriales were the dominant archaea during the digestion of seaweeds. Extensive research on microbial dynamics and the application of co-digestion is still needed to achieve complete utilization of biomass coupled with biogas enhancement.

Declining carbohydrate solubilization with increasing solids loading during fermentation of cellulosic feedstocks by Clostridium thermocellum: documentation\xa0and diagnostic tests

BackgroundFor economically viable 2nd generation biofuels, processing of high solid lignocellulosic substrate concentrations is a necessity. The cellulolytic thermophilic anaerobe Clostridium thermocellum is one of the most effective biocatalysts for solubilization of carbohydrate harbored in lignocellulose. This study aims to document the solubilization performance of Clostridium thermocellum at increasing solids concentrations for two lignocellulosic feedstocks, corn stover and switchgrass, and explore potential effectors of solubilization performance.ResultsMonocultures of Clostridium thermocellum demonstrated high levels of carbohydrate solubilization for both unpretreated corn stover and switchgrass. However, fractional carbohydrate solubilization decreases with increasing solid loadings. Fermentation of model insoluble substrate (cellulose) in the presence of high solids lignocellulosic spent broth is temporarily affected but not model soluble substrate (cellobiose) fermentations. Mid-fermentation addition of cells (C. thermocellum) or model substrates did not significantly enhance overall corn stover solubilization loaded at 80 g/L, however cultures utilized the model substrates in the presence of high concentrations of corn stover. An increase in corn stover solubilization was observed when water was added, effectively diluting the solids concentration mid-fermentation. Introduction of a hemicellulose-utilizing coculture partner, Thermoanaerobacterium thermosaccharolyticum, increased the fractional carbohydrate solubilization at both high and low solid loadings. Residual solubilized carbohydrates diminished significantly in the presence of T. thermosaccharolyticum compared to monocultures of C. thermocellum, yet a small fraction of solubilized oligosaccharides of both C5 and C6 sugars remained unutilized.ConclusionDiminishing fractional carbohydrate solubilization with increasing substrate loading was observed for C. thermocellum-mediated solubilization and fermentation of unpretreated lignocellulose feedstocks. Results of experiments involving spent broth addition do not support a major role for inhibitors present in the liquid phase. Mid-fermentation addition experiments confirm that C. thermocellum and its enzymes remain capable of converting model substrates during the middle of high solids lignocellulose fermentation. An increase in fractional carbohydrate solubilization was made possible by (1) mid-fermentation solid loading dilutions and (2) coculturing C. thermocellum with T. thermosaccharolyticum, which ferments solubilized hemicellulose. Incomplete utilization of solubilized carbohydrates suggests that a small fraction of the carbohydrates is unaffected by the extracellular carbohydrate-active enzymes present in the culture.

Single cell oil production from hydrolysates of alkali pre-treated giant reed: High biomass-to-lipid yields with selected yeasts

Single cell oil (SCO) produced by oleaginous yeasts represents an intriguing source for second generation biofuels or other biobased oleochemicals. This study aimed at improving SCO production from giant reed (Arundo donax L.). Five different yeast species were used to evaluate the lipid yield and fatty acids profile obtained in six media prepared with two enzymatic hydrolysates of mild alkali pre-treated giant reed fibers (washed or not after filtration) and variable nitrogen supplementation (three levels). After pre-treatment and hydrolysis, up to 489 ± 9 mg of reducing sugars per g of initial untreated biomass were obtained. C/N ranged widely (38−258) among the different formulated media, depending on both washing and nitrogen supplementation, and strongly affected SCO accumulation by most of the strains. Lipomyces starkeyi, Rhodosporidiobolus azoricus, and Cutaneotrichosporon oleaginosum reached the highest lipid contents (54–68%) and concentrations (4.8–5.6 g/L). The highest lignocellulosic biomass-to-lipid conversions were obtained with C. oleaginosum, R. azoricus, and L. starkeyi (102 ± 9, 95 ± 9, and 89 ± 3 mg of lipids per g of untreated giant reed biomass, respectively). Oleic, palmitic, linoleic, and stearic acid were predominant in the fatty acids profile, similarly to seed oils. In conclusion, hydrolysates derived from the alkali pre-treated biomass of giant reed are suitable to obtain high lipid yields with selected yeasts, to be used for the biobased industry.

CaCO3-derived from eggshell waste for improving the corrosion resistance of zinc composite coating on mild steel for biodiesel storage tank

Sustainability of energy does not end in the generation of biofuels, but as well encompasses proper mitigation of the metallic equipment used in the plant from corrosion degradation. Corrosion of metallic equipment in biodiesel plants limits the storage and distribution of biodiesel to the end-users. Carbon steel of Mild steel type/grade is one of the major metallic materials used in the construction of biodiesel storage tanks. The major setback of using mild steel for biodiesel storage is the high corrosion rate. This research aims to develop a novel coating of mild steel using CaCO3 derived from eggshell waste (ESP). The Codeposition method was used to develop Zn-10%CaCO3-ESP (single and double layer). The corrosion of the samples was tested in a Jatropha curcas biodiesel (JBD) environment. Microstructure, hardness values, viscosity, and density of the oil were determined. A corrosion protection efficiency of 68.87% was obtained using the Zn-10%CaCO3-ESP double layer. High corrosion damage as a result of localized pitting corrosion mechanism was observed for the mild steel without coating. This novel coating can be used in the industrial fabrication of storage tanks for biodiesel since the CaCO3-ESP is prepared by a simple method.

Evaluation of the Catalytic Activity of Metal Phosphates and Related Oxides in the Ketonization of Propionic Acid

In recent years, the upgrading of lignocellulose bio-oils from fast-pyrolysis by means of ketonization has emerged as a frontier research domain to produce a new generation of biofuels. Propionic acid (PA) ketonization is extensively investigated as a model reaction over metal oxides, but the activity of other materials, such as metal phosphates, is mostly unknown. Therefore, PA ketonization was preliminarily investigated in the gas phase over both phosphates and oxides of Al, Zr, and La. Their catalytic activity was correlated to the physicochemical properties of the materials characterized by means of XRD, XRF, BET N2 porosimetry, and CO2- and NH3-TPD. Noteworthy, monoclinic ZrO2 proved to be the most promising candidate for the target reaction, leading to a 3-pentanone productivity as high as 5.6 h−1 in the optimized conditions. This value is higher than most of those reported for the same reaction in both the academic and patent literature.

Laminar Flame Characteristics of 2,5-Dimethylfuran (DMF) Biofuel: A Comparative Review with Ethanol and Gasoline

Since the early years of the 21st century, the whole world has faced two very urgent problems: the depletion of fossil energy sources and climate change due to environmental pollution. Among the solutions sought, 2,5-Dimethylfuran (DMF) emerged as a promising solution. DMF is a 2nd generation biofuel capable of mass production from biomass. There have been many studies confirming that DMF is a potential alternative fuel for traditional fuels (gasoline and diesel) in internal combustion engines, contributing to solving the problem of energy security and environmental pollution. However, in order to apply DMF in practice, more comprehensive studies are needed. Not out of the above trend, this paper analyzes and discusses in detail the characteristics of DMF's combustible laminar flame and its instability under different initial conditions. The evaluation results show that the flame characteristics of DMF are similar to those of gasoline, although the burning rate of DMF is much higher than that of gasoline. This shows that DMF can become a potential alternative fuel in internal combustion engines.

Generation of biofuel from anaerobic digestion of Scenedesmus obliquus grown in energetic‐laden industrial wastewater: Understanding microalgae strains, co‐digestants, and digestate toxicity

AbstractMicroalgae as a substrate for anaerobic digestion (AD) offer promising outcomes over other conventional feedstocks. In this work, the generation of biofuel in the form of biogas via AD using wastewater‐grown microalgae was investigated. In particular, batch screening of different microalga strains and co‐substrates, culminated into the evaluation of biomethane potential (BMP) from AD of Scenedesmus obliquus grown in energetic‐laden wastewater through benchtop‐scale semi‐continuous reactor. Effectiveness of AD was evaluated for biogas yield, volatile solids (VS) removal, and kinetics for various microalga strains as potential substrate candidates. High carbon content co‐digestants were also investigated including return activated sludge and waste office pulped paper. At semi‐continuous scale, the specific BMPs associated with of 15, 20, and 30 days hydraulic residence times (HRT) were determined as 67.0, 86.6, and 86.3 ml CH4/g VS (added) with average methane content of 70%. In addition, toxicological assessments showed that AD effluent was benign towards renew growth of biomass, thus showing the potential for nutrients recover.

Recent developments in the biology and biotechnological applications of halotolerant yeasts.

Natural hypersaline environments are inhabited by an abundance of prokaryotic and eukaryotic microorganisms capable of thriving under extreme saline conditions. Yeasts represent a substantial fraction of halotolerant eukaryotic microbiomes and are frequently isolated as food contaminants and from solar salterns. During the last years, a handful of new species has been discovered in moderate saline environments, including estuarine and deep-sea waters. Although Saccharomyces cerevisiae is considered the primary osmoadaptation model system for studies of hyperosmotic stress conditions, our increasing understanding of the physiology and molecular biology of halotolerant yeasts provides new insights into their distinct metabolic traits and provides novel and innovative opportunities for genome mining of biotechnologically relevant genes. Yeast species such as Debaryomyces hansenii, Zygosaccharomyces rouxii, Hortaea werneckii and Wallemia ichthyophaga show unique properties, which make them attractive for biotechnological applications. Select halotolerant yeasts are used in food processing and contribute to aromas and taste, while certain gene clusters are used in second generation biofuel production. Finally, both pharmaceutical and chemical industries benefit from applications of halotolerant yeasts as biocatalysts. This comprehensive review summarizes the most recent findings related to the biology of industrially-important halotolerant yeasts and provides a detailed and up-to-date description of modern halotolerant yeast-based biotechnological applications.

The Influences of Promising Feedstock Variability on Advanced Biofuel Production: A Review

The contribution of biofuels is expected to continuously increase in the global fuel market, as they are environmentally-friendly and provide renewable energy. Four generations of biofuels are categorized and are primarily based on their feedstock sources and the production technologies that are used. The influence of promising feedstock types and the availability on the production technologies and the fuel properties of advanced-generation biofuels are not systematically examined in the literature. Hence, this research extensively reviews the potential impact of feedstock sources and their variability on the production and characteristics of biofuels. The approaches of theoretical analysis and inference referred to relevant works in the literature were applied. The findings suggest that the potency of the commercialized mass production of advanced-generation biofuels is facilitated by a much more flexible selection and the sufficient availability of promising feedstocks. Lignocellulose biomass is recognized as the most significant feedstock source for second-generation biofuels, while microalgae do the same for third-generation biofuels. Moreover, the microalgae of some strains are able to produce the highest amount of bio-alcohol of all available feedstock sources. The cell walls of lignocellulose biomass and microalgae mostly consist of lignin compounds and cellulose materials, respectively. Biological pretreatment is considered to be the most promising process, prior to biofuel production. The biofuel yields from lignocellulose biomass and microalgae, using biological pretreatments, could increase by 120% and 22-159%, respectively, in comparison with those of any other pretreatment process. Moreover, more double bonds and larger unsaturated fatty acids in raw lipids cause the inferior oxidative stability, but superior fluidity of biofuel. The possible impact of Genetically-Modified Crops (GMC) on the eco-environment and human genes remains a serious concern and requires further tracking and analysis. Genetically-modified technology is still immature to achieve the expected characteristics of biofuels from those modified crops. The unceasing exploitation of promising biomass feedstock sources is crucial for the rapid and steady development of advanced-generation biofuels.

Algae: A potential feedstock for third generation biofuel

Due to increase in population and augmented usage of conventional fuels; raised interest among scientist to find some potential substitute of conventional fuels for sustainable development, because these fuels are limited and also non-renewable. Many alternative fuels such as biodiesel, ethanol, methanol, synthetic fuels, hydrogen, biogas, natural gas, etc. have been used as internal combustion (IC) engines fuels. Liquid biofuels gained lot of attention as alternative to fossil fuels because it can be derived from renewable biomass resources. The first-generation biofuels originate dispute over food versus fuel as most of the feedstocks are edible. In this regard, algae have emerged as a vital source of production of third generation biofuels, such as bioethanol, biohydrogen, biopropane etc. In some cases the oil yield from microalgae are better as compared to several oil producing crops. Microalgae are photosynthetic microorganisms which convert sunlight, water, and carbon dioxide to sugars, from which macromolecules, such as lipids and triacylglycerols can be obtained. In this paper, the detailed information about algae, its cultivation techniques and lipid extraction for the production of biofuels have been discussed. The characterization of the fuel obtained by algae and its application as diesel engine fuel have also covered in this paper.

Biofuel Generation by Macro and Micro Algae as a Renewable Energy Source: A Systematic Review

Recently, the fossil fuel consumption is increasing owed to industrial revolution which leads to serious human health and environmental problems. For sustainable energy generation and survival of human life and earth planet biofuel is an alternative source of energy. Non-renewable energy causes environmental effects which results in environmental degradation, to overcome these problems biofuel is the best environmental friendly option. Biofuel can be generated from different types of biomass, among these algae have potential to produce considerable amount of biofuel. But it is very difficult task to produce algal biofuel from specific type of algae. The present review compares and discusses the different types of feedstock, methods of oil production and improvement of method for biodiesel production and their utilization. This review mainly focuses on the cultivation and methodology for biofuel generation and recovery from algae for sustainable development.

Potential utilization of turpentine oil as an alternative fuel

After the oil price rise in 1973, and increased global pollution; individual, social and national life and economy were largely affected by the increasing cost of energy. Rapidly increasing prices of petroleum, its crisis, and uncertainties regarding the availability of petroleum have serious effect on the development of economy all over the world. The fuel trends for transportation vehicles have been affected greatly by both availability of fuel and environmental factors. To address these energy and environmental issues, it is essential to find some potential alternative to fossil fuel. Biofuels derived from biological materials; basically, renewable sources have emerged as potential alternative to fossil fuel. Turpentine oil is one of the vital biofuels and biodegradable fuel source which has the potential to replace partially the diesel fuel. Commencing from the biofuel generations, the current paper discusses about the production methods of turpentine oil, its important physicochemical properties and application as diesel engine fuel.

Industrial applications of Ananas comosus wastes as valuable and utilizable products- A review

Ananas comosus, tropical fruit from Bromeliaceae family, is known for its flavour with major application in a number of industries viz juice, canned pulp, fruit candy, jam, jelly, wine, vinegar, bromelain extraction and many more. Large amounts of by-products are generated from these industries in which peel alone accounts for 34-38%. These by-products are discarded as waste and causes serious environmental pollution. Researchers have investigated that these by-products, mainly peels are potential sources of many nutritional and bioactive compounds which exhibits numerous health benefits. The present application of the waste is to convert it into value added products and currently, it is utilized in many industries such as chemical industry, health sectors, food sector, pharmaceuticals, and nutraceuticals. This article summarizes the major applications of A. comosus peel at industrial level. ‘Industrial applications’ is an umbrella term in which biofuel generation; enzyme production; bromelain extraction; cellulose, bacterial cellulose, nanocellulose and nanocrystalline cellulose; nanoparticles synthesis; biorefinery production; superabsorbent hydrogel formation; oil extraction; wine and vinegar production; supplementation; fortification; enrichment etc. terms are embedded.