Alternative Biofuel Production Research Articles

Computational and Experimental Studies on Combustion and Co-Combustion of Wood Pellets with Waste Glycerol.

The shortage of fossil fuels and their rising prices, as well as the global demand for renewable energy and the reduction in greenhouse gas (GHG) emissions, result in an increased interest in the production of alternative biofuels, such as biodiesel or biomass pellets. In this study, the possibility of utilizing waste glycerol, as an addition to pine pellets intended for heating purposes, has been investigated. The usefulness of pellets containing glycerol additions has been compared in terms of applicable quality standards for wood pellets. The highest values of moisture (4.58%), ash (0.5%) and bulk density (650 kg/m3) were observed for pellets without glycerin waste. The addition of waste glycerol slightly increases the calorific value of the pellet (17.94 MJ/kg for 7.5% additive). A 10-kW domestic biomass boiler has been employed to burn the tested pellets. The consumption of analyzed fuels during boiler operation was determined. The concentration of CO, CO2 and NOx in exhaust gases has also been examined. It was observed that the addition of 7.5% of waste glycerol contributes to the reduction in NOx concentrations by 30 ppm and CO2 by 0.15%. The obtained experimental results were compared with the numerical calculations made with the use of ANSYS Chemkin-Pro. The conducted research indicates the legitimacy of utilizing waste glycerol as an additive to wood pellets. In addition, this type of addition has a positive effect on, among others, the increase in calorific value, as well as lower emissions of combustion products such as NOx and CO2.

Biofuels from cyanobacteria -a metabolic engineering approach

The concern about the limited availability of petroleum-based fuels and their role in increasing CO2 levels in the atmosphere has sparked significant attention toward biofuel and bioenergy production. The global pursuit of sustainable energy sources has catalyzed innovative research into alternative biofuel production strategies. Transforming CO2 into usable fuels and chemicals is gaining even more prominence. Cyanobacteria, renowned for their photosynthetic ability, have emerged as promising candidates for biofuel synthesis. Their ability to convert solar energy and carbon dioxide into valuable biofuels makes them a compelling avenue for sustainable energy solutions. Using metabolic engineering principles, researchers have endeavored to optimize cyanobacterial metabolic pathways, enhance photosynthetic efficiency, and redirect carbon flux toward biofuel precursors. Numerous species of cyanobacteria offer genetic and metabolic traits that facilitate manipulation, and their photosynthetic characteristics imply that carbohydrates, fatty acids, and even alcohol could serve as potential renewable sources for biofuels. This review showcases cyanobacteria's ability as a biofuel source and emphasizes the transformative influence of metabolic engineering employed in the creation and production of "cyanofuels”

Concomitant strategy of wastewater treatment and biodiesel production using innate yeast cell (Rhodotorula mucilaginosa) from food industry sewerage and its energy system analysis

In many recent studies, the wastewater with high organic matter and high utilization value compounds was treated using yeast. It decreases the effluent contaminants and makes it applicable for reuse in many food industries. This present study focuses on the combined approach of treatment and biorefinery to increase the circular economy in food industries. The two primary goals of the work were to screen the potential oleaginous yeast from the food industry effluent (FIE) collected from the food flavourant producing industry and used for FIE remediation through bioaugmentation and to extract microbial oil of yeast biomass harvested after remediation. Further, the extracted microbial oil was trans-esterified to produce biodiesel. The process of transesterification was optimized for its influencing parameters. After 10 days of treatment of FIE with the yeast cell, the treatment efficiency was analyzed and found to be precise with the typical discharge value. The overall lipid content of the oleaginous yeast (Rhodotorula mucilaginosa SML) used for the FIE treatment was 67.95 w/w% of dry cell biomass. The extracted microbial oil was used for transesterification; the process was optimized through the one-variable analysis approach and response surface methodology optimization using a central composite design. The transesterification process showed maximum conversion (98%) at oil to methanol ratio - 5.0, catalyst concentration - 2.8% and time - 1.15 h. The fatty acid composition and the physicochemical characteristics were compatible with petroleum diesel, making it applicable for alternative biofuel production. Thus, this concomitant strategy has proved efficient for reducing contaminants in FIE and suggested a new sustainable source for biodiesel production. The exergy, energy and mass balance analysis of the biodiesel conversion process proved that this process is the most economically viable one to increase the circular economy of food industries.

Continuous-flow CvFAP photodecarboxylation of palmitic acid under environmentally friendly conditions

The fatty acid photodecarboxylase from Chlorella variabilis NC64A (CvFAP) promotes the elimination of CO2 from fatty acids (Cn) producing the corresponding hydrocarbon (Cn-1). Therefore, this enzyme is of great biotechnological interest since it can be used in alternative biofuel production routes matching the concept of green chemistry. However, due to its recent discovery, this reaction still requires optimizations, which was the focus of the present work together with the application of continuous flow system. The results in batch reactors showed the importance of using high power LED lamps (300 W) to reduce the reaction time for full conversion (30 min, >99%). In another approach, a continuous flow system demonstrated high potential, as it enabled full conversion with a half concentration of enzyme extract in a very short residence time of 15 min. Furthermore, the use of less expensive and sustainable light sources, not previously reported for reactions with CvFAP, were evaluated with full conversion (>99%) after 1 h for continuous flow reactions using 300 W common white LED lamp and based preliminary batch reactions investigations using direct sunlight. Thus, important advances and new perspectives for CvFAP photodecarboxylation reactions could be achieved with the present report.

Optimization of Liquid Hot Water Pretreatment and Fermentation for Ethanol Production from Sugarcane Bagasse Using Saccharomyces cerevisiae

Sugarcane bagasse can be considered a potential raw material in terms of quantity and quality for the production of alternative biofuels. In this research, liquid hot water (LHW) was studied as a pretreatment process to enhance the digestibility of pretreated material for further conversion into bioethanol. Different variables (temperature, residual time, and acid concentration) were determined to predict the optimized condition. LHW pretreatment showed an impact on the hemicellulose structure. The optimized condition at 160 °C for 60 min with 0.050 M acid concentration reached the highest glucose yield of 96.86%. Scanning electron microscopy (SEM) showed conspicuous modification of the sugarcane bagasse structure. The effect of LHW pretreatment was also demonstrated by the changes in crystallinity and surface area analysis. FTIR techniques revealed the chemical structure changes of pretreated sugarcane bagasse. The prepared material was further converted into ethanol production with the maximized ethanol concentration of 19.9 g/L.

Metabolic transformation of cyanobacteria for biofuel production

World-wide, an emerging demand is moving towards the biofuels to replace the fossil fuels. In alternative biofuel production strategies, cyanobacteria have unique characteristic of accumulating glycogen, lipid, and fuel molecules through natural mechanisms. Moreover, the cyanobacteria can be easily engineered to synthesis a plenty of fuel molecules from CO2. To obtain the fuel molecule from cyanobacteria, various techniques were invented in which the metabolic engineering is found to be a prerequisite to develop an economically feasible process. The expression of indigenous or heterologous pathways plays an important role in developing successful production process. In addition, the engineering of photosynthetic apparatus, destruction of competitive pathways and improvement of tolerance were also proven to improve the product specific synthesis. Although various metabolic engineering approaches have been developed, there are certain obstacles when it comes to implementation for the production. In this review, the important biosynthetic pathways for biofuels, alteration of other genes to improve the actual pathway and possibilities of developing cyanobacterial fuel production have been elaborated.

Thermochemical Characterization of Eight Seaweed Species and Evaluation of Their Potential Use as an Alternative for Biofuel Production and Source of Bioactive Compounds.

Algae are underexplored resources in Western countries and novel approaches are needed to boost their industrial exploitation. In this work, eight edible seaweeds were subjected to their valorization in terms of nutritional characterization, thermochemical properties, and bioactive profile. Our results suggest that seaweeds present a rich nutritional profile, in which carbohydrates are present in high proportions, followed by a moderate protein composition and a valuable content of ω-3 polyunsaturated fatty acids. The thermochemical characterization of seaweeds showed that some macroalgae present a low ash content and high volatile matter and carbon fixation rates, being promising sources for alternative biofuel production. The bioactive profile of seaweeds was obtained from their phenolic and carotenoid content, together with the evaluation of their associated bioactivities. Among all the species analyzed, Porphyra purpurea presented a balanced composition in terms of carbohydrates and proteins and the best thermochemical profile. This species also showed moderate anti-inflammatory activity. Additionally, Himanthalia elongata extracts showed the highest contents of total phenolics and a moderate carotenoid content, which led to the highest rates of antioxidant activity. Overall, these results suggest that seaweeds can be used as food or functional ingredient to increase the nutritional quality of food formulations.

Experimental investigation on fast pyrolysis of freshwater algae. Prospects for alternative bio-fuel production

Several technologies have been developed with the aim of obtaining fuels from algae. In the present work, the fast pyrolysis of three different types of microalgae (Botryococcus braunii, Spirulina platensis, and Pithophora sp.) is investigated focusing on the quality and yield of the liquid product as a potential biofuel. The characterization of microalgae shows an elevated content of lipids in Botryococcus braunii, higher levels of proteins in Spirulina, and an equal number of proteins and carbohydrates in Pithophora sp. A fixed bed reactor, connected to a vacuum system, and nitrogen as inert gas flow are used in the pyrolysis experiments at 300, 400, 500, and 600 °C. At 500 °C, Botryococcus braunii produces the maximum amount of pyrolytic oil (65% yield) while Spirulina and Pithophora sp. affords the greatest amount at 600 °C, in 45% and 28% yield, respectively. Gas chromatography-mass spectrometry (GC–MS) analysis of the Botryococcus braunii-derived oils shows a high content of long-chain derivatives of alcohols, carboxylic acids, and unsaturated hydrocarbons. On the other hand, Spirulina-derived oil consists mostly of nitrogenated compounds while oil from Pithophora sp. is composed of oxygenated and/or nitrogenated products, depending on the reaction temperature. The measured higher heating value (HHV) of Botryococcus braunii-derived oil produced at 500 °C is 45 MJ/kg and this bio-oil could be used as a feedstock for fuel production after chemical upgrading to decrease the oxygen content (6.59 wt%).

Production of butanol from biomass: recent advances and future prospects.

At present, diminishing oil resources and increasing environmental concerns have led to a shift toward the production of alternative biofuels. In the last few decades, butanol, as liquid biofuel, has received considerable research attention due to its advantages over ethanol. Several studies have focused on the production of butanol through the fermentation from raw renewable biomass, such as lignocellulosic materials. However, the low concentration and productivity of butanol production and the price of raw materials are limitations for butanol fermentation. Moreover, these limitations are the main causes of industrial decline in butanol production. This study reviews butanol fermentation, including the metabolism and characteristics of acetone-butanol-ethanol (ABE) producing clostridia. Furthermore, types of butanol production from biomass feedstock are detailed in this study. Specifically, this study introduces the recent progress on the efficient butanol production of "designed" and modified biomass. Additionally, the recent advances in the butanol fermentation process, such as multistage continuous fermentation, metabolic flow change of the electron carrier supplement, continuous fermentation with immobilization and recycling of cell, and the recent technical separation of the products from the fermentation broth, are described in this study.

Carbohydrate Yield and Biomethane Potential from Enzymatically Hydrolysed <i>Saccharina latissima</i> and Its Industrial Potential

The demand for fuel for utilisation of machinery and transport has culminated in large amounts of fossil fuel usage in the last century. The environmental dangers attached with the usage of fossil fuels have created a large demand for alternative sources of fuels. There is an array of polysaccharides contained within macroalgae, such as mannitol, cellulose and laminarin. These polysaccharides have potential for production of alternative biofuels; however, they are not easily accessible for biological digestion. By pretreatment of macroalgae with enzymes, these polysaccharides may be easier to access by microbes, allowing effective utilization in anaerobic digestion. Saccharina latissima, available in abundance on the Norwegian coast line, is a brown macroalgae with a high level of carbohydrates. This study assesses the ability for utilisation of enzymatically pre-treated Saccharina latissima for production of biogas through anaerobic digestion. The harvested Saccharina latissima was analysed to contain 30.11 ± 2.30 g of reducing sugars per 100 g of dry sample upon enzymatic hydrolysis. This was able to yield 459 ± 30 mL per gVS of biogas through anaerobic digestion, with a methane content of 56%. This suggests a biomethane potential of 1760 m3 per ha of productive sea floor growing Saccharina latissima. An evaluation of this process has been performed to demonstrate the industrial potential of Saccharina latissima in biogas production.

Feasibility and Sustainability of Bioethanol Production from Starchy restaurants’ Bio-wastes by New Yeast Strains

The study treats an important and imperious worldwide problem. It deals with the production of alternative biofuels from starchy restaurants’ bio-waste. The starchy wastes of the restaurants, especially in developing countries, are produced in huge quantities that represent a sustainable substrate for ethanol production. So, we aimed to study the feasibility of the conversion of the starchy wastes to biofuel (bioethanol) using different pretreatments and new yeast strains. Our results approved the feasibility of conversion of the starchy wastes into biofuel. Using of thermo-acidic hydrolysis, we obtained 360 g of free and fermentable sugars from each dry kg of the wasted materials. Pichia barkeri and Candida intermedia were introduced as new species for the field of biofuel production in addition to the classical Saccharomyces cerevisiae. Among them, S. cerevisiae KKUY-0301 produced 11.5 g/L of ethanol from 27 g of sugars. Its transformation rate was 82% of the theoretical yield, i.e. 1 kg of the waste could produce 150 g of ethanol. Optimization of the cultural conditions approved that 4 days of incubation, pH 5, 35 °C and 5% of the yeast inoculum (108 cell/mL) were the most appropriate conditions that could induce the maximum production bioethanol. This study recommends the application of this technology on a commercial scale all over the world to benefit from all types of bio-wastes. In addition, our findings offer a crucial solution for the recycling the restaurant starchy waste materials into ecofriendly product “biofuel” that reduce the overall cost production of the bioenergy and make it a competitive to the oil-based energy.

BioFuelDB: a database and prediction server of enzymes involved in biofuels production.

BackgroundIn light of the rapid decrease in fossils fuel reserves and an increasing demand for energy, novel methods are required to explore alternative biofuel production processes to alleviate these pressures. A wide variety of molecules which can either be used as biofuels or as biofuel precursors are produced using microbial enzymes. However, the common challenges in the industrial implementation of enzyme catalysis for biofuel production are the unavailability of a comprehensive biofuel enzyme resource, low efficiency of known enzymes, and limited availability of enzymes which can function under extreme conditions in the industrial processes.MethodsWe have developed a comprehensive database of known enzymes with proven or potential applications in biofuel production through text mining of PubMed abstracts and other publicly available information. A total of 131 enzymes with a role in biofuel production were identified and classified into six enzyme classes and four broad application categories namely ‘Alcohol production’, ‘Biodiesel production’, ‘Fuel Cell’ and ‘Alternate biofuels’. A prediction tool ‘Benz’ was developed to identify and classify novel homologues of the known biofuel enzyme sequences from sequenced genomes and metagenomes. ‘Benz’ employs a hybrid approach incorporating HMMER 3.0 and RAPSearch2 programs to provide high accuracy and high speed for prediction.ResultsUsing the Benz tool, 153,754 novel homologues of biofuel enzymes were identified from 23 diverse metagenomic sources. The comprehensive data of curated biofuel enzymes, their novel homologs identified from diverse metagenomes, and the hybrid prediction tool Benz are presented as a web server which can be used for the prediction of biofuel enzymes from genomic and metagenomic datasets. The database and the Benz tool is publicly available at http://metabiosys.iiserb.ac.in/biofueldb& http://metagenomics.iiserb.ac.in/biofueldb.

ALTERNATIVE PRODUCTION OF BIO-FUEL FROM THE BYE PRODUCTS OF OIL SPILLAGE

Analytical approach in identifying of ecologically effective methods for oil spills purification were investigated and new effective method of alternative biofuel production from the bye products of oil spillage were proposed.

Sweet Sorghum and Upland Rice: Alternative Preceding Crops to Ameliorate Ethanol Production and Soil Sustainability Within the Sugarcane Cropping System

The objective of this study was to assess the effect of preceding crops (soybeans, sunn hemp, upland rice, and sweet sorghum) on the succeeding sugarcane yield, total bioethanol production, and soil chemical properties within the sugarcane cropping system. Treatments with upland rice and sweet sorghum provided the greatest increase in soil available P, compared to uncultivated land (control) at the final sampling, preceding the sugarcane harvest. Treatments effects were not significantly different for soil organic matter. At sugarcane harvest, the upland rice treatment provided the highest cane yield compared to the unplanted land, yet was not significantly higher than the yield of the sweet sorghum treatment. The highest sugarcane ethanol yields were observed in the sweet sorghum–sugarcane and upland rice–sugarcane treatments. However, the total ethanol yield in both preceding and succeeding crops was found to be highest in the sweet sorghum treatment, followed by the upland rice treatment. Upland rice proved to be most suitable for farming systems which emphasized food security, whereas sweet sorghum was most desirable for farming systems which emphasized alternative biofuel production. Both crops improved the sustainable production of soil and sugarcane.

Continuous production of palm biofuel under supercritical ethyl acetate

The interesterification of palm oil in supercritical ethyl acetate (ETA) to produce fatty acid ethyl ester (FAEEs) or biofuel was conducted in a continuous tubular reactor. The density of the mixtures in the system was estimated using the Peng–Robinson equation of state process simulator, and the residence time was calculated. The effects of the reaction conditions, including the molar ratios of palm oil to ethyl acetate, the temperature, and the pressure, were investigated under various mass flow rates of the mixtures and optimized. The results showed that reaction temperatures above 653K and long residence times affected the content of FAEEs and triacetin, a valuable by-product. The addition of water to the mixture in a 1:30:10M ratio of palm oil to ethyl acetate to water at 653K, 16MPa, and a mixture mass flow rate of 1.5g/min increased the total production of FAEEs and triacetin from 90.9 to 101.5wt% in 42.4min. The main finding of the present study is that triglyceride associated with ETA hydrolysis used to form acetic acid protected the products from decomposition at high temperatures and long residence times. The results will aid the selection of an efficient and economical process for alternative biofuel production from palm oil in supercritical ETA.

Quantifying spatial dependencies, trade‐offs and uncertainty in bioenergy costs: an Australian case study (2) – National supply curves

AbstractA biophysically constrained economic analysis of several alternative biofuel production pathways develops upper and lower bounds on national supply cost curves, taking into account implicit spatial dependencies and trade‐offs. As well as land (and sea) transport suitable biofuels, we also consider electricity and aviation biofuels. One feedstock (crop residues from grains) and five bioenergy pathways illustrate this approach for Australia. The methods are, however, applicable to any feedstock, bioenergy technology, region, or scale. Biofuel production costs, dependent on the spatial concentration of available feedstock, are derived in a companion paper by selecting a cost minimizing production scale. Lower concentrations imply smaller processing plants and greater collection areas and costs. Any candidate production plant location can have a collection area that approximates the least cost for its average spatial concentration, because feedstock concentration varies only modestly within cost minimizing area scales. A set of plant locations, scales, and near to least‐cost collection areas, is found that collectively service all the available residue feedstock using Australian data. This generates upper and lower bounds on nationally aggregated supply cost curves. The sizing of biofuel facilities will be also affected by investment scale commercial considerations, including the reliability of feedstock and investor appetite for risk: these are discussed qualitatively. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd

Farm-Scale Cost of Producing Perennial Energy Cane as a Biofuel Feedstock

Energy cane varieties are high-fiber sugarcane clones which represent a promising feedstock in the production of alternative biofuels and biobased products. This study explored the crop establishment and whole farm production costs of growing energy cane as a biofuel feedstock in the southeastern USA. More specifically, total production costs on a feedstock dry matter biomass basis were estimated for five perennial energy cane varieties over alternative crop cycle lengths. Variable production costs for energy cane production were estimated to be in the $63 to $76 Mg−1 range of biomass dry matter for crop cycles through harvest of fourth through sixth stubble crops. Total production costs, including charges for fixed equipment costs, general farm overhead, and land rent, were estimated to range between $105 and $127 Mg−1 of feedstock biomass dry matter material.

Alternative Technologies for Biofuels Production in Kraft Pulp Mills—Potential and Prospects

The current global conditions provide the pulp mill new opportunities beyond the traditional production of cellulose. Due to stricter environmental regulations, volatility of oil price, energy policies and also the global competitiveness, the challenges for the pulp industry are many. They range from replacing fossil fuels with renewable energy sources to the export of biofuels, chemicals and biomaterials through the implementation of biorefineries. In spite of the enhanced maturity of various bio and thermo-chemical conversion processes, the economic viability becomes an impediment when considering the effective implementation on an industrial scale. In the case of kraft pulp mills, favorable conditions for biofuels production can be created due to the availability of wood residues and generation of black liquor. The objective of this article is to give an overview of the technologies related to the production of alternative biofuels in the kraft pulp mills and discuss their potential and prospects in the present and future scenario.

Thermochemical processing of macroalgae: a late bloomer in the development of third-generation biofuels?

This article offers a critical overview of the recent developments in thermochemical processing of macroalgae, a field that has been comparatively neglected when viewed against the vast wealth of research into alternative biofuel production methods and feedstocks. However, advances in thermochemical techniques have led to a flurry of activity into the applicability and use of macroalgae. Recent research has demonstrated that macroalgae may be used to produce bioresources in a similar way to many conventional terrestrial feedstocks and, indeed, may also possess a number of advantages (notably by not competing for land that could be used for food and forestry, nor requiring extensive use of nitrogenous fertilizers). With this in mind, it is suggested that many of the criticisms that have led to previous disinterest in thermal processing of macroalgae are not valid. Nevertheless, only through the continuation of these recent endeavors can macroalgal biomass, via broader and successively larger scale experimentation, demonstrate itself to be a competitive source of renewable energy.

Biomass to dimethyl ether by gasification/synthesis technology-an alternative biofuel production route

Technical and economic analysis was done for the biomass to dimethyl ether (DME) technology to promote the gasification/synthesis route for biofuel production and its application as a fossil fuel substitute. The technology of biomass gasification/synthesis has obvious advantages, including production flexibility, environmental friendliness, economic feasibility, and application versatility. Biomass gasification/synthesis technology integrates bio-DME synthesis, fertilizer production, electricity generation, and waste heat utilization to convert waste biomass residues to DME for use as liquid petroleum gas, transportation fuel substitute, and chemical intermediates, which has been proven to be one of the most effective and clean biomass utilization routes. The 1000 t/a-scale demonstration plant has a bio-DME production rate of 6 to 7tbiomass/tDME, biomass gasification efficiency of ⩾82%, once-through CO conversion of ⩾70%, DME selectivity (DME/DME + other organic products) of ⩾90%, and a total system efficiency of ⩾38%. The demonstration plant also has self-sufficient steam and electricity supply. The 10,000tons/a-scale bio-DME production cost with or without feedstock subsidy is estimated to be 1968 Yuan/t and 2868 Yuan/t, respectively in China. Because of the limitation in biomass feedstock collection cost, massive and disperse commercial plants with a capacity of 10000 t/a bio-DME are more suitable for rural areas.