Oil Feedstock For Biodiesel Production Research Articles

Optimization of ultrasound-assisted biodiesel production from python fat oil using response surface methodology

Diversification of oil feedstocks for biodiesel production is very necessary to reduce dependence on traditional vegetable oils and animal fats. Therefore, a conventional and ultrasound-assisted single-step transesterification process was optimized using response surface methodology (RSM) for biodiesel production from a novel feedstock python fat oil (PFO). Second-order polynomial models of the conventional (CM) and ultrasound-assisted (USM) methods were used to predict the biodiesel yield, and the coefficient of determination (R2) was found to be at 0.9946, and 0.9873, respectively. The optimal biodiesel yield of USM calculated from the model is 99.12% with the following reaction conditions: PFO/methanol ratio of 33.77% wt.%, PFO/KOH ratio of 1.05 wt.%, and reaction time of 128.53 min. Biodiesel yield results under optimal conditions have demonstrated that the regression models are consistent with experimental data. Besides, the biodiesel yield of USM (98.90%) was significantly higher than that of CM (92.73%). In particular, the properties of PFO biodiesel produced under optimal conditions were found to agree with EN 14214 standard specifications. In summary, single-step biodiesel production from the PFO new feedstock with USM can be commendably used to engender and adopt a more sustainable and environmentally friendly energy approach.

Trichosanthes kirilowii Maxim seed kernel oil: The optimization of ultrasound-assisted extraction and evaluation of its potential as a novel biodiesel feedstock

As a promising source of diesel, non-edible oil derived from phytomass is an attractive option for biodiesel production and has attracted more and more attentions due to its numerous advantages. Trichosanthes kirilowii Maxim seed is one such promising, un-explored and un-edible oil feedstock for biodiesel, which stores high content of oil. To evaluate the possibility of T. kirilowii seeds kernel oil (TKSO) as feedstock of biodiesel, the optimum conditions of ultrasonic-assisted extraction TKSO and physicochemical properties of TKSO and TKSO biodiesel were investigated. The results exhibited that under optimum extraction conditions, TKSO yield (51.62%) was closed to the oil content of T.kirilowii seeds kernel (54.23%). TKSO mainly contained six types of fatty acids, including two saturated fatty acids (12.17%) and four unsaturated fatty acids (87.83%). The physicochemical properties of TKSO biodiesel including cold filter plugging point, pour point, flash point, calorific value, sulphur content and kinematic viscosity were in agreement with biodiesel standards (GB/T 25199-2017 and ASTM standard). Therefore, ultrasonic-assisted extraction was an effective method for TKSO, which as an alternate green resource had the potential application in biodiesel production. This research provided a basis for selecting suitable non-edible oil extraction methods and non-edible oil feedstocks for biodiesel production.

Evaluation of Ukrainian Camelina sativa germplasm productivity and analysis of its amenability for efficient biodiesel production

Camelina or false flax ( Camelina sativa ) is an emerging crop that is currently considered one of the most promising feedstock for production of vegetable oil-based liquid biofuels: biodiesel and jet biofuel. Originally, camelina comes from the East European region, where this crop used to be widely cultivated before it was substituted with other oilseed crops, such as rapeseed, sunflower, etc. Due to increasing interest in biofuel production and sustainable agriculture, camelina has re-emerged as a viable oil-rich crop of multiple purposes. However, camelina varieties are not free from some undesirable traits, one of which is low yields. Over the recent years, extensive research efforts have been dedicated to breeding and improving this crop although this work has been restricted by limited genetic diversity of camelina. This limitation can be overcome by using unexploited germplasm, which previously was not involved into the camelina breeding process. In present study, we aimed to evaluate the productivity potential of unexploited Ukrainian spring camelina varieties and to perform comprehensive estimation of their suitability for use as oil feedstock for biodiesel production. The productivity data of all nine existing Ukrainian varieties of spring camelina was assessed for the 2001–19 period, based on the available data. It has been established that average productivity of the analyzed cultivars is 1756 kg/ha in the Ukrainian Forest-Steppe zone and 1146 kg/ha in the Steppe zone. The latter is characterized by a dryer climate, which significantly impacts spring camelina seed yields and thus their oil outputs, which are crucial for biofuel production. Potential rates of FAME- and FAEE-based biodiesel production have been evaluated. The conducted comprehensive analysis suggests that cultivation of spring camelina for biofuel production purposes can be more sustainable and feasible in the Forest-Steppe zone, rather than in the Steppe zone. Finally, a brief investigation of potential obstacles, impacting the production efficiency and feasibility of different biodiesel types, has also been conducted, as well as potential solutions were proposed for them. The obtained results create strong background for further efficient camelina breeding and for analyses of techno-economic feasibility of production camelina-based biofuels in Eastern Europe and specifically in Ukraine. • Performance of unexploited Ukrainian camelina germplasm was first evaluated. • Productivity of Ukrainian varieties of camelina was assessed for the 2001–19 period. • The average camelina yields were 1.76 t/ha in Forest-Steppe and 1.15 t/ha in Steppe. • Camelina oil yields depends more on seed yield, rather than seed oil content. • Biodiesel production rates were 726.53 and 374.96 L/ha in Forest-Steppe and Steppe.

Inedible oil feedstocks for biodiesel production: A review of production technologies and physicochemical properties

Biodiesel emits lesser harmful pollutant emissions than renewable and biodegradable ones compared diesel. Research confirms that edible products and crops are the major sources of biofuel production. Excessive usage of these crops leads to higher production costs, economic imbalance, and depletion of food supply. Biofuel production from inedible sources shall lower the drawbacks of edible products and crops. Inedible feedstocks are the sustainable source of biofuel production as they are mostly grown on waste/abandoned land, produce similar or higher yields than edible feedstocks, and are fairly cost-effective. Hence this present work reviews the challenges and possibilities of employing inedible oil and products as a potential feedstock for biofuel production. Salient features of inedible oil such as production technologies, cost and benefits, fatty acid and physicochemical properties and oil extraction technology are reviewed from the latest literature. The outcome of this study suggests that there is a huge prospect of utilizing inedible oil as a reliable feedstock for biofuel generation. Among various production processes, scCO2 extraction technology proved to reduce inedible oil's moisture by 70% and FFA content by 62%, with a higher conversion rate of about 97%, as methanol in supercritical conditions has lesser interaction with the FFA of inedible oil. Inedible feedstocks are effective, non-toxic and safe in biofuel production. However, there exists a challenge in restricting its development in large-scale commercialization.

Identification of novel, non-edible oil seeds via scanning electron microscopy as potential feedstock for green synthesis of biodiesel.

In the present era, environmental glitches associated with extensive emission of greenhouse gases (GHG) and energy crises caused by exhausting fossil fuel reservoirs has diverted researcher's interest toward alternative and renewable energy sources. Biodiesel is a renewable, biodegradable, and sustainable alternative to petro-diesel. Biodiesel synthesized from non-edible seed oils is preferred due its cost effectiveness and eco-friendly nature. Hence, our present study focused on investigation and identification of micromorphological characters of six novel, non-edible seed oil feedstock for biodiesel production via scanning electron microscopy (SEM). Results of light microscopy of seeds revealed distinct variation in seed size (15.8-1.8 mm in length and 9.4-1.1 in width), shape (round to Cuneiform), and color (from black to yellowish green). Non-edible seed oil content fall in range of 28-38% (wt/wt). Free fatty acid (FFA) content varied from 0.56 to 2.06 mg KOH/g. Multivariate analysis was performed to investigate correlation between three significant variables of seed oil yielding feedstock such as potential for biodiesel synthesis, oil content, and FFA content via principal component analysis. Ultra morphological investigation of seeds surfaces via SEM exhibited distinctive variation in surface sculpturing, cell arrangement, cell shape, periclinal wall shape, margins, protuberances, and anticlinal wall shape. Seed surface sculpturing varied from reticulate, semitectate, wrinkled, rugose, papillate, perforate, and striate. Periclinal wall arrangements confirmed variation from glabrous, raised, depressed, elevated, smooth, pentagonal, entire, and ripple margins. Whereas, anticlinal walls pattern demonstrated variation from angular, smooth, wavy, deep, dentate, entire, irregular, puzzled, elongated, curved, and depressed. Finally, it was concluded from obtained results that SEM could be a possible useful tool in disclosing veiled micromorphological characters of non-edible oil yielding seeds, which provides useful information to researchers for their correct, authentic identification, and classification in modern synthetic system.

Ultrasonic assisted oil extraction and biodiesel synthesis of Spent Coffee Ground

Spent Coffee Ground (SCG) was studied as a potential source of oil feedstock for biodiesel production as an alternative waste utilisation instead of being disposed as municipal waste. This study evaluated the ultrasonic assisted oil extraction from SCG, which was followed by biodiesel conversion via transesterification. Hexane was found to be the most effective extractant for SCG oil. Soxhlet extraction could obtain maximum SCG oil yield of 12.5% within 3 h whereas the highest SCG oil yield (14.52%) using ultrasonic extraction was obtained at hexane to SCG ratio of 4 mL g−1 and at 30% ultrasonic amplitude for 30 min. The improved oil yield with shorter extraction time was due to the ultrasonic fragmentation on SCG cells, which enhanced the interactions between oil and solvents. Fourier transform infrared analysis showed that the SCG oil possessed suitable functional groups for biodiesel conversion. Then, the SCG oil was successfully converted to biodiesel via ultrasonic assisted transesterification. The optimal FAME yield (97.11%) was achieved with molar ratio of methanol to SCG oil of 30:1, 4 wt% of catalyst concentration, at 30% ultrasonic amplitude and for 3 h. The produced SCG biodiesel has promising properties which adhere to the biodiesel standards but acid value was beyond the permissible limit which could be overcome by utilising as blend feedstock with other commercially available biodiesel. The high calorific value along with low viscosity, density and corrosion properties suggested SCG biodiesel as an interesting and viable option for biodiesel blending.

Life cycle assessment of waste cooking oil for biodiesel production using waste chicken eggshell derived CaO as catalyst via transesterification

There are plentiful experimental studies on biomass as heterogeneous catalyst and its reasonable cost, it can be a potential catalyst feedstock for biodiesel production. This study presents the life cycle assessment (LCA) of waste cooking oil biodiesel production catalyzed by waste chicken eggshell derived CaO catalyst to validate the suitability of waste chicken eggshell as a green catalyst in biodiesel field. To the best of our knowledge, LCA was first performed for the heterogeneous catalyst, CaO preparation as a subsystem in a biodiesel production. Comparative studies were performed to evaluate the difference of environmental impacts contributed by waste cooking oil, WCO biodiesel production catalyzed by waste chicken eggshell derived CaO with the two different production processes via Jatropha oil as the oil feedstock and potassium hydroxide, KOH as the homogeneous catalyst. Utilization of WCO as the oil feedstock for biodiesel production has lesser environment impact than the Jatropha oil as the WCO biodiesel production does not involve agriculture phase. Likewise, utilization of waste chicken eggshell derived CaO catalyst (heterogeneous catalyst) has less contribution on the overall impact categories than KOH (homogeneous alkali-based catalyst) as the production of KOH required addition of chemical and additives, plus complex purification and neutralization processes are required during the production phase. The overall impact results clearly indicated the best environmental performance of waste chicken eggshell derived CaO of 1.17 Pt was over the traditional KOH catalyst and implementation of Jatropha oil but also identified some bottlenecks that should be addressed for more sustainable solutions.

Extraction and esterification of waste coffee grounds oil as non-edible feedstock for biodiesel production

The potential of waste coffee grounds (WCG) as a non-edible feedstock for biodiesel production was evaluated in term of extraction and esterification of waste coffee grounds oil (WCGO). The effect of liquid-solid extraction parameters such as the type and volume of solvent, the extraction time and temperature, and mixing speed were thoroughly investigated. The highest yield of oil extracted from WCGO was 15.47 wt% obtained at a hexane to WCG ratio of 9:1 (v/w) with a mixing speed of 200 rpm and an extraction duration of 5 min at room temperature. An esterification reaction was conducted as a pre-treatment step to reduce the concentration of free fatty acid (FFA), optimized by response surface methodology (RSM) combined with a central composite design (CCD). The results indicated that all the parameters including the methanol (MeOH) to FFA molar ratio, quantity of catalyst, reaction time and temperature were significant for %FFA removal. In the esterification step, the FFA conversion was 95% at the predicted optimization condition which corresponded to the experimental data. Therefore, the results of this study support the utilization of WCGO as a source of non-edible oil feedstock for biodiesel production.

Smart utilization of jatropha (Jatropha curcas Linnaeus) seeds for biodiesel production: Optimization and mechanism

Jatropha curcas Linnaeus (Jatropha curcas L.) seeds have been found to be an ideal sustainable and low-cost source of catalyst and oil feedstock for biodiesel production. Jatropha cake, remained dregs after jatropha curcas oil (JCO) extraction, has been treated by two different techniques; calcination and potassium hydroxide (KOH) activation to be used as novel heterogeneous catalysts for the transesterification reaction. The effect of calcination and KOH activation on the jatropha cake has been characterized. The basic strength and basicity of the catalysts have been determined as well. The effect of different operating conditions has been studied using JCO and waste cooking oil (WCO) to evaluate the efficiency of the catalysts. The catalysts produced higher biodiesel yield using JCO than WCO. In the case of using JCO, the two catalysts produced close biodiesel yield. Calcined jatropha cake (CJC) has been chosen as the optimum catalyst for its better reusability and lower preparation cost than KOH activated jatropha cake (KJC). The optimum operating conditions of the JCO transesterification process has been determined as 60min reaction time, 6:1 methanol to oil molar ratio, 1wt.% catalyst loading, 400rpm and 60°C. Biodiesel production yield of JCO was achieved to 94 and 96% with CJC and KJC catalysts.

Enhancement of lipid extraction for improved biodiesel recovery from the biodiesel promising microalga Scenedesmus obliquus

During the transesterification of oil feedstock for biodiesel production, the reaction primarily happens at the ester bonds where the fatty acid chains meet the glycerol. Therefore, only esterified fatty acids (EFAs) are able to be turned directly into biodiesel by transesterification. In this study, an optimized procedure for EFAs recovery from the biodiesel promising microalga Scenedesmus obliquus was studied. The effect of different solvent mixtures (ratios), extraction times, pretreatments and cell-disruption methods on intracellular EFAs and free fatty acids (FFAs) yield was examined. Using of chloroform:methanol (C:M) 2:1 for 2 h was shown to be the best solvent mixture for lipid extraction which resulted in the highest EFAs yield. Furthermore, testing of different cell-disruption methods showed that cell-disruption is not essential for lipid extraction from S. obliquus cells. Although, microwave pretreatment showed significant increase in EFAs yield with respect to overnight oven drying at 80 °C, all showed insignificant differences to the control. Moreover, overnight cell freezing showed 7.7% significant reduction in EFAs yield with respect to the control, while hot-water treatment for 5 min showed significant increase by 13.7%. On the other hand, overnight cell incubation, in oven or freezing, resulted in significant increase in FFAs up to 7.44 and 12.47 mg g−1 of the dry weight, respectively. In addition, the present study showed that no pretreatment with isopropanol to inactivate the lipases is needed when hot-water pretreatment is performed. This study suggested that hot-water pretreatment not only deactivate lipases, but also enhances the EFAs recovery.

Phosphatidic acid phosphatase and diacylglycerol acyltransferase: potential targets for metabolic engineering of microorganism oil.

Oleaginous microorganism is becoming one of the most promising oil feedstocks for biodiesel production due to its great advantages in triglyceride (TAG) accumulation. Previous studies have shown that de novo TAG biosynthesis can be divided into two parts: the fatty acid biosynthesis pathway (the upstream part which generates acyl-CoAs) and the glycerol-3-phosphate acylation pathway (the downstream part in which three acyl groups are sequentially added onto a glycerol backbone). This review mainly focuses on two enzymes in the G3P pathway, phosphatidic acid phosphatase (PAP) and diacylglycerol acyltransferase (DGAT). The former catalyzes a dephosphorylation reaction, and the latter catalyzes a subsequent acylation reaction. Genes, functional motifs, transmembrane domains, action mechanism, and new studies of the two enzymes are discussed in detail. Furthermore, this review also covers diacylglycerol kinase, an enzyme that catalyzes the reverse reaction of diacylglycerol formation. In addition, PAP and DGAT are the conjunction points of the G3P pathway, the Kennedy pathway, and the CDP-diacylglycerol pathway (CDP-DAG pathway), and the mutual transformation between TAGs and phospholipids is discussed as well. Given that both the Kennedy and CDP-diacylglycerol pathways are in metabolic interlock (MI) with the G3P pathway, it is suggested that, via metabolic engineering, TAG accumulation can be improved by the two pathways based on the pivotal function of PAP and DGAT.

Efficient biodiesel production from phospholipids-containing oil: Synchronous catalysis with phospholipase and lipase

Recently, the use of low quality oils as potential alternative oil feedstock for biodiesel production has become more and more attractive, which provides a feasible solution to reduce the cost of biodiesel production. However, in the low quality oils, expect triglycerides, other lipids represented by phospholipids also exist. It was found that the presence of phospholipids showed adverse effect on enzyme catalyzed biodiesel production. Therefore, it is necessary to develop an effective method for the conversion of phospholipids-containing oils. In recent years, the employment of free lipase in catalyzing biodiesel from refined oils has received great attentions due to its advantages of lower cost and faster reaction rate. To further promote its application in efficient conversion of phospholipids-containing oils, a synchronous catalysis together with phospholipase and lipase for biodiesel production from phospholipids-containing oils was developed. A high FAME yield of 94.9% can be obtained even with 10% phospholipids contained in the oil feedstock. Further study showed that the biodiesel product could also meet the phosphorus demand of EN14214 standard. Moreover, the good reuse stability of the two enzymes further indicates that the combination catalysis of phospholipase and lipase is very promising for biodiesel production especially with high phospholipids-containing oils as feedstock.

Potential non-edible oil feedstock for biodiesel production in Africa: A survey

Africa is a continent full of untapped natural resources ranging from biodiversity to vast water bodies but faced with food and energy crises. Prices of fuel are also escalating. With researchers and experts scrambling for the solution, biodiesel from vegetable oil will receive more attention. But the edible feedstock as the obvious cheapest choice will not be sustainable enough for the increasing energy and food demand; hence, there is a need for guaranteed feedstock. This study was therefore undertaken to explore feedstock that would not be suitable for food but useful for biodiesel in Africa. Among the highlight areas of the study include current energy situation in Africa, technologies of biodiesel production, current state of biodiesel in Africa, driving forces for increase in biodiesel production, current existing problems of biodiesel commercialization, potential benefits of biodiesel processes, need for non-edible oil plants, potential non-edible biodiesel feedstock, biology, distribution and chemistry of the selected non-edible oil plants. The study also throws light on the implication of biodiesel on the environment and the outlook. From the study, the use of non-edible oils can be guaranteed as sustainable feedstock for biodiesel since most of the non-edible plants can be grown on wastelands to reclaim them, not compete with food crops for limited lands, are relatively cheap, available and offer similar or even higher yields of biodiesel and fuel properties as the edibles. Developing biodiesel industry in Africa can help curb the high rate of unemployment through job creation as well as increase in income level of the rural populace. Weaning African economies from oil import dependencies could also be an economic achievement. It can be deduced from the study that there are promising non-edible oil resources in the system for biodiesel industrialization in Africa.

Biodiesel production from biobutanol. Improvement of cold flow properties

Experimental design methods have been successfully applied to develop and optimize the process of synthesis of butyl esters from rapeseed oil (RSO), the most common oil feedstock for biodiesel production in Europe and used frying oil (UFO), as a cheaper raw material, using biobutanol, and potassium methoxide (KOCH3) as catalyst. The optimum conditions were found to be a catalyst concentration of 1.1% and 0.9%, an operation temperature of 78°C and 80°C for rapeseed oil butyl esters (RSOBE) and used frying oil butyl esters (UFOBE), respectively, obtaining ester yields of 96.86% and 96.54% with 6:1 biobutanol/oil molar ratio. Results show that biodiesel produced using biobutanol as alcohol in the transesterification process improved cold flow properties in terms of cloud point (CP), pour point (PP) and cold filter plugging point (CFPP) without significantly affecting the other fuel properties.In order to determine the effects of long storage on oxidation stability, the biodiesel samples were stored for a period of 12months, the analysis of fuel properties: peroxide value (PV), acid value (AV), iodine value (IV) and viscosity (ν) have been applied in oxidation studies. According to the results obtained, the RSOBE and UFOBE samples showed a good oxidative stability during the storage period. The resulting butyl esters can be used as a diesel fuel substitute, since it matches the European Biodiesel Standard EN 14214.

Effect of Culture Conditions on the Production of Microbial Oils fromMortierellasp.

Microbial oils are the lipids obtained from microorganisms such as bacteria and fungi. They have the ability to produce oils under certain special culture conditions. Microbial oils might become one of the potential oil feedstocks for biodiesel production in the future. In the present work, the effects of culture conditions on the biomass and lipid production of Mortierella sp. were studied. The favourable pH, temperature and media were found to be 6.0, 25°C and yeast extract peptone glucose (YPG) media, respectively. Under these conditions, M. polycephala yielded the highest biomass (9.1 g/L) compared with M. vinaceae (8.2 g/L) and M. alpina (5.9 g/L); at pH 6.0, M. alpina yielded the highest biomass of 17.60 g/L compared with M. vinaceae, which produced 15.20 g/L and M. polycephala, 15.05 g/L. The effect of different media like YPG, fat producing media and potato dextrose broth was studied; a maximum growth of about 17.34 g/L was observed in M. alpina compared with M. polycephala (15.03 g/L) and M. vinaceae (15.63 g/L), respectively, in YPG media. The lipid content was found to be maximum in M. polycephala, i.e. about 1.95 g/L, and M. alpina was found to be the least yielding, i.e. about 0.007 g/L, at 25°C. Thin layer chromatography was performed using the isolated lipid extracts to determine the constituents, and it showed the presence of myristic, palmitic and stearic acids. The estimated iodine values were 81 g of I2/100 g of oil for the lipids extracted from M. polycephala, exhibiting higher unsaturated lipid contents than other two fungal species, i.e. M. vinaceae (79 g of I2/100 g of oil) and M. alpina (59 g of I2/100 g of oil). The acid values of the fungi followed a similar pattern as that of the iodine values as the free fatty acid content was more in M. polycephala. Peroxide values varied in M. polycephala (1.49 mg KOH/g oil) than those of M. vinaceae (1.20 mg KOH/g oil) and M. alpina (0.31 mg KOH/g oil). Hence, M. polycephala was the major strain considered for producing good quality oil compared with M. vinaceae and M. alpine, and it can be effectively utilised to produce microbial biodiesel.

Long-term storage oxidation stability of Karanja biodiesel with the use of antioxidants

Vegetable oils and their esters (biodiesel) undergo oxidation and degenerate more quickly than mineral diesel. The unsaturated fatty acids present in vegetable oils are susceptible to oxidation. One of the main criteria used for the quality assessment of biodiesel is ‘storage oxidation stability’. Oxidation of the esters during the long-term storage can lead to problems in the utilization of biodiesel in the engine and can lead to rough engine operation. Contact with ambient air, exposure to sunlight, metals, and exposure to high temperature conditions accelerate the oxidation reactions leading to lower oxidation stability of biodiesel. The EU biodiesel standard (EN14214) specifies a minimum value of 6h for biodiesel induction period at 110°C, measured using Rancimat instrument. In order to ensure the oxidation stability specification limit 6h for biodiesel at the filling station, the initial oxidation stability at the time of production should be definitely higher than 6h. Addition of synthetic antioxidants is an efficient way to increase the initial oxidation stability of biodiesel. Reduction in oxidation stability can be minimized during long-term storage, if biodiesel is stored in suitable conditions because some conditions lead to quick reduction in oxidation stability.Present experimental study investigates the effectiveness of five antioxidants viz. 2,6-di-tert butyl-4-methyl phenol (BHT), 2-tert butyl‐4-methoxy phenol (BHA), 2-tert butyl hydroquinone (TBHQ), 1,2,3 tri-hydroxy benzene (PY) and 3,4,5-tri hydroxy benzoic acid (PG) on the long-term storage oxidation stability of Karanja oil methyl esters (KOME), which is produced from a very popular highly unsaturated, non-edible oil feedstock for biodiesel production in Indian sub-continent. All the samples were stored in dark room and in air-tight bottles. The aim of this study is to find the most effective antioxidant and the minimum concentration of antioxidant required to meet the storage oxidation stability specifications. KOME samples were stored in different storage conditions (viz. in dark/sunlight exposure, with air/without air exposure, with metal/without metal exposure) at ambient temperature with an aim to assess the effect of storage conditions on the oxidation stability and the most appropriate conditions for biodiesel storage.

Development of a Saccharomyces cerevisiae strain for increasing the accumulation of triacylglycerol as a microbial oil feedstock for biodiesel production using glycerol as a substrate

Triacylglycerol (TAG) is a microbial oil feedstock for biodiesel production that uses an inexpensive substrate, such as glycerol. Here, we demonstrated the overproduction of TAG from glycerol in engineered Saccharomyces cerevisiae via the glycerol-3-phosphate (G3P) pathway by overexpressing the major TAG synthesis. The G3P accumulation was increased 2.4-fold with the increased glycerol utilization gained by the overexpression of glycerol kinase (GUT1). By overexpressing diacylglycerol acyltransferase (DGA1) and phospholipid diacylglycerol acyltransferase (LRO1), the engineered YPH499 (pGutDgaLro1) strain produced 23.0 mg/L lipids, whereas the YPH499 (pESC-TRP) strain produced 6.2 mg/L total lipids and showed a lipid content that was increased 1.4-fold compared with 3.6% for the wild-type strain after 96 h of cultivation. After 96 h of cultivation using glycerol, the overall content of TAG in the engineered strain, YPH499 (pGutDgaLro1), yielded 8.2% TAG, representing a 2.3-fold improvement, compared with 3.6% for the wild-type strain. The results should allow a reduction of costs and a more sustainable production of biodiesel.

Using crude glycerol and thin stillage for the production of microbial lipids through the cultivation of Rhodotorula glutinis

Single cell oils (SCO) produced from oleaginous microorganisms are a potential alternative oil feedstock for biodiesel production. The worldwide production of glycerol, a 10% (w/w) byproduct produced in the transesterfication process of oils converted to biodiesel, is increasing as more biodiesel is being produced. For the purposes of cost reduction, crude glycerol was regarded as a suitable carbon source for the cultivation of Rhodotorula glutinis. In addition to using renewable crude glycerol, waste solution collected from the brewing company (called thin stillage) was adopted as a substitute to replace a costly nitrogen source used in the medium. The results of using mixture of crude glycerol and thin stillage indicated about a 27% increase in total biomass as compared to that of using crude glycerol with a standard medium. Using glycerol instead of glucose as the carbon source could also alter the lipid profile, resulting in an increase in linolenic acid (C18:2) to comprise over 20% of the total lipid. Successfully using renewable crude glycerol and thin stillage for the cultivation of oleaginous microorganisms could greatly enhance the economic competition of biodiesel produced from SCO.

Complementary biodiesel combination from tung and medium-chain fatty acid oils

The complementary blending of tung oil biodiesel with coconut oil and palm kernel oil biodiesels was investigated to improve the biodiesel properties. Tung oil is considered a potential non-edible oil feedstock for biodiesel production. However, tung oil biodiesel has unfavorable fuel properties, including a high density, kinematic viscosity, and iodine value and low oxidation stability because of the high content of α-elaeostearic acid (C18:3). In contrast, medium-chain saturated fatty acid methyl esters (FAMEs) such as lauric acid methyl ester (C12:0) is the predominant component in palm kernel oil and coconut oil biodiesels. The palm kernel oil and coconut oil biodiesels exhibited a low density, kinematic viscosity, and iodine value as well as high oxidation stability, features that are complementary to the deficiencies of tung oil biodiesel. An optimum blending ratio obtained comprised the COME, PKME, and TME at a weight ratio of 20:20:60. Most of the fuel properties of the optimum biodiesel blend could meet the biodiesel specifications, with the exception of the oxidation stability. In addition, the multiple linear correlations between the properties of biodiesel blends and their FAME composition were established. Furthermore, the effectiveness of butylated hydroxyanisole (BHA), N,N′-di-sec-butyl- p -phenylenediamine (PDA), and tert-butylhydroquinone (TBHQ) at concentrations between 1000 and 20,000 ppm was investigated to improve the oxidation stability of the biodiesel blend. ► Coconut and palm kernel oil biodiesels were complementary to tung oil biodiesel. ► An optimal ratio of coconut, palm kernel, and tung oil biodiesels was 20:20:60 wt.%. ► N,N′-di-sec-butyl- p -phenylenediamine was suggested to stabilize the biodiesel blend.

An optimum biodiesel combination: Jatropha and soapnut oil biodiesel blends

Jatropha (Jatropha curcas) and soapnut (Sapindus mukorossi) oils are considered potential non-edible oil feedstocks for biodiesel production and present complementary fuel properties. Apparently, the poor oxidation stability of jatropha oil biodiesel and the high cold filter plugging point of soapnut oil biodiesel can be successfully improved to satisfy all biodiesel specifications at an optimum blending ratio. The optimum biodiesel combination was further blended with diesel at various volumetric percentages to evaluate the variations of fuel properties. The biodiesel–diesel blends up to B40 would show the satisfactory fuel properties.