Potential Feedstock For Biodiesel Production Research Articles

Experimental Investigation and Optimization of Non-Catalytic In-Situ Biodiesel Production from Rice Bran Using Response Surface Methodology Historical Data Design

Rice bran oil (RBO)is claimed to be a potential feedstock for biodiesel production. Non-catalytic in-situ biodiesel production from a low-cost feedstock (rice bran) using subcritical ethanol-water mixture was investigated in this study. The influence of four independent variables, i.e., addition of co-solvent, ethanol concentration, temperature, and time of reactions, on the yield of biodiesel was examined. The results showed that the most effective co-solvent wasethyl acetate and the optimum ethanol concentration, temperature and reaction time were 80% v/v, 200 oC and 3 hours, respectively. The maximum yield of biodiesel was found to be around 80%. The optimization of operating conditions was carried out by response surface methodology (RSM) with historical data design (HDD). The statistical method also suggested similar optimum operating conditions, i.e., 78.44% (v/v) ethanol concentration, 200 oC, and 3.2 hours reaction time with ethyl acetate as a co-solvent. The predicted maximum biodiesel yield was also slightly lower, i.e., 76.98%. Therefore, this study suggests that biodiesel production from rice bran through a non-catalytic in-situ process using a subcritical ethanol-water mixture with ethyl acetate as a co-solvent is very feasible since the yield can reach 80%. The study also found that RSM with HDD can predict the optimum operating conditions with a good accuracy.

Improving cold flow properties of palm fatty acid distillate biodiesel through vacuum distillation

Palm fatty acid distillate (PFAD), a by-product of refining process of crude palm oil can be used as a potential feedstock for biodiesel production. However, the application of palm oil-based biodiesel is often hinder by its poor cold flow properties (CFP). Biodiesel fuel with poor CFP may crystallize and result in clogging of fuel lines, filters and injectors that cause engine operability problems. For that, a vacuum distillation method was designed and its feasibility and efficiency in improving the CFP was examined. A total of 13.60wt% of total saturated fatty acid methyl esters were successfully removed from the PFAD biodiesel, resulting in the improvement of the cloud point (CP), cold filter plugging point (CFPP) and pour point (PP) of PFAD biodiesel from 20 °C, 19 °C, and 15 °C to 13 °C, 11 °C, and 9 °C, respectively. It is remarkable that the improved CFPP satisfied the requirements for grade C summer biodiesel for temperate climates in EN 14212 standard. Additionally, Sarin (UFAME) empirical correlation was evaluated and it was found to have a good prediction of CFP for PFAD biodiesel, with lower than 2 °C deviation.

Effects of antioxidant and ceramic coating on performance enhancement and emission reduction of a diesel engine fueled by Annona oil biodiesel

BackgroundA broad investigation on alternative source of energy has been going on to find a solution to multi-faceted fossil fuel concerns namely exhaustion of fuels, energy demand, harmful emissions and environmental impact. Biodiesel is an environment-friendly and renewable alternative for diesel. In the present work, Annona seed oil has been assessed as a potential feedstock for biodiesel production. MethodsA100 was characterized by FTIR and GC-MS. Propyl Gallate (PG) was characterized by morphological study using FESEM. The elemental analysis of PG was measured using EDAX analysis. YPSZ coating was found suitable to make out the potential of A100 in diesel engine. PCCU was designed to reduce the emissions by the liquid reductant in the catalyst system. The process optimization was performed by RSM and factorial experimental design. FindingsWith the YPSZ coated engine, improved characteristics of combustion and performance were noticed with A100+PG. A significant diminution on CO, HC and smoke emissions were perceived with A100+PG+CE. In addition, the work was expanded with the application PCCU for the lessening of NOx. A gradual decrement in NOx was observed with A100+PG+CE. Subsequently, A100+PG+CE with PCCU was deliberated as more prominent than other fuel samples in view of its engine characteristics.

Biodiesel preparation from Semen Abutili (Abutilon theophrasti Medic.) seed oil using low-cost liquid lipase Eversa® transform 2.0 as a catalyst

To decrease the cost of biodiesel production, undeveloped nonedible Semen Abutili seed oil (SASO) was first used as a feedstock to prepare biodiesel. Some low-cost liquid lipases were screened and used as green catalysts for biodiesel production via the ethanolysis of SASO. The effect of reaction factors on ethanolysis was optimized by the response surface methodology (RSM). The results demonstrated that SASO was a promising alternative feedstock, and Eversa® Transform 2.0 showed the best performance for biodiesel production from low-quality SASO feedstock (high FFA and phospholipid contents). In addition, Eversa® Transform 2.0 can be reused 3 times without significant loss. The influence of reaction factors on biodiesel yield decreased in the order of reaction temperature > lipase load > reaction time. The maximum biodiesel yield was 94.2 ± 1.3 % under the optimal conditions (lipase load 6%, water content 20 %, 7:1 (mol/mol) ethanol to SASO, 11 h, 37 °C). The kinetic parameters (Vmax and K'm) of the transesterification of SASO were 4.16 × 10−2mol/(L∙min) and 5.27 × 10-1 mol/L, respectively. The Arrhenius equation and activation energy, Ea, of Eversa® Transform 2.0-catalyzed transesterification of SASO were lnV0 = 4.8252–2382.3/T and 19.80 kJ/mol, respectively. The biodiesel produced from SASO was accordance with the ASTM D6751 standard, except for the oxidation stability. Thus, SASO, an undeveloped nonedible low-quality vegetable oil, can be used as a potential feedstock for biodiesel production, and the low-cost liquid lipase Eversa® Transform 2.0 can be used for biodiesel production.

Production Of Biofuel From Sesame Oil And Its Characterization As An Alternative Fuel For Diesel Engine

Depletion of petroleum fuels and their rising cost have directed towards an intensive search for substitute fuels. In the present work, a potential feedstock for biodiesel production is identified as sesame oil biodiesel. Raw sesame oil is collected from the market and biodiesel from raw oil is produced through the trans-esterification process in the laboratory. A highest biodiesel yield of 92.1% was achieved, when esterification process is performed with 10:1 ethanol to oil ratio and 2.3% sodium hydroxide at 60 °C for 90 min. Thermo-physical properties are investigated with the help of different experimental apparatus. Comparison with Bureau of Indian Standards (IS 15607:2016) reveals the suitability of sesame oil biodiesel used as an alternative fuel for compression-ignition engine. Experimental study is performed for different blends of sesame oil biodiesel and diesel fuel (SOEE20, SOEE40, SOEE60, SOEE80, SOEE100), mineral diesel and raw sesame oil to recognize the suitability of blends to be use as a fuel for diesel engine.

Chemical and Enzymatic transesterification of rubber seed oil – A comparative study

Biodiesel produced from a wide variety of vegetable oils is expected to replace diesel fuel. Conventional diesel engines are the major sources of expelling the particulate matter, soot, smoke and oxides of nitrogen to the environment which are harmful. Biodiesel is an attractive alternative fuel to replace petroleum derived diesel because it is environment friendly and can be produced from edible or non-edible vegetable oils. The conflict between food and fuel led to the identification of more than fifty non-edible oil sources for biodiesel production. Utilization of locally available non-edible oil sources for production of biodiesel reduces the cost of fuel and increases production interest. Rubber seed oil is a non-edible type vegetable oil, identified as a potential feedstock for biodiesel production. This paper comprises the synthesis of biodiesel from high free fatty acid rubber seed oil through transesterification by chemical and enzymatic methods. The transesterification of rubber seed oil with chemical catalyst and enzyme catalyst were investigated in the work. The variables affecting the reaction such as molar ratio, catalyst concentration, time and temperature were analysed. Kinetic study was carried out to find the reaction constants and activation energy of both chemical and enzymatic transesterification reactions. The properties of fuel such as kinematic viscosity, calorific value and specific gravity were found out and compared with the properties of diesel. Base catalyst concentration was varied from 0.5wt% to 2wt% for alkaline transesterification process and the result revealed that maximum yield of 90% was obtained with a base catalyst concentration of 1.5wt% with 1:9 molar ratio at 55± 3°C. The best condition arise in enzymatic reaction was 10wt% enzyme and 1:4 methanol ratio with 5wt% addition of water as the solvent.

Experimental Investigation and Optimization of Non-Catalytic In-Situ Biodiesel Production from Rice Bran Using with RSM Historical Data Design

Biodiesel has become one of the essential fuels in the present and future, and it can be produced from vegetable oil and animal fat. However, current feedstocks to produce biodiesel slow down the growth of biodiesel implementation due to the high cost of feedstock. As a result, rice bran oil (RBO) is claimed to be a potential feedstock for biodiesel production. A non-catalytic in-situ biodiesel production from low cost feedstock (RBO) using subcritical ethanol-water mixture probably decrease the production cost further and environmentally benign. Therefore, in this work the influence of four independent variables, adding co-solvent/without co-solvent, ethanol concentration, temperature, and time of reactions on the yield of biodiesel was examined tentatively. The independent variables limitations were (a) co-solvent of n-hexane, ethyl acetate and chloroform, (b) ethanol concentration of 20 - 80 %, v/v, (c) temperature of reaction 120 - 200 oC, and (d) time of reaction 1 - 4 h employed to direct the trials. In this examination historical data design was utilized and a quadratic polynomial model was built up and after that at last optimized by using response surface methodology (RSM). It was found that the yield of biodiesel achieved an optimum value of 79.79 %, v/v using ethyl acetate as co-solvent with ethanol concentration of 78.83 % (v/v), under constant operation conditions of P = 8 Mpa, T = 160 oC, t = 2 h, N = 400 rpm, ratio of rice bran (RB): solvent: co-solvent= 10 (g): 80 mL: 20 mL. In the other hand (rice bran 2), it was found that the yield of biodiesel achieved an optimum value of 76.98 % for 3.2 h of reaction time and temperature of reaction 200 oC, under constant operation conditions of P = 8 Mpa, co-solvent = ethyl acetate, ethanol concentration = 80 %, v/v, N = 400 rpm, ratio of RB: solvent: co-solvent= 10 (g): 80 mL: 20 mL. The examination has likewise uncovered that authentic plan information with RSM is a well-organized statistical technique for forecasting the optimum operating conditions of a non-catalytic in-situ biodiesel production from rice bran using subcritical ethanol-water mixture assumes a crucial role of ethanol concentration, types of co-solvent, temperature and time of reactions.

Candlenut oil: review on oil properties and future liquid biofuel prospects

The rapid depletion of diesel fuel, increasing energy demand, and environmental pollution concerns are increasing worldwide interest in the production of liquid biofuels. Biofuel (bio-aviation and biodiesel) is a potential and plausible alternative to diesel fuel to substantially mitigate the environmental impact of future energy demand. Non-edible crop oil is viewed as a potential feedstock for liquid biofuel production owing to the massive demand for edible oil as a food source. However, the major limitation of utilizing non-edible crop oil for biodiesel production is the cost due to the high price of feedstocks and the limited supply of large-scale biodiesel production. Candlenut trees can grow in harsh and arid climates due to low moisture requirements. Therefore, candlenut can be cultivated in the most unused lands, particularly in developing countries along coasts and riverbanks and in deserts and other wastelands unsuitable for edible crops. Additionally, candlenut seed contains a high amount of oil (30%-60%). Thus, candlenut oil is a promising source for commercial biodiesel production. The present study was conducted to review the possibilities and challenges of utilizing candlenut as a potential feedstock for biodiesel production. Additionally, several important aspects related to candlenut oil processing, such as extraction technology, physicochemical properties, biodiesel production technologies, and advantages and limitations of candlenut biodiesel production are discussed.

Optimization of ultrasound-assisted oil extraction from Canarium odontophyllum kernel as a novel biodiesel feedstock

In this novel study, oil was extracted from the kernel of an exotic indigenous species known as Canarium odontophyllum via an ultrasound-assisted process. The extraction process was optimized using response surface methodology (RSM) based on the Box-Behnken experimental design (BBD). The optimal conditions for the investigated parameters were determined as ultrasound amplitude level: 38.30%, ratio of n-hexane to kernel powder: 50:1 in mL/g, extraction time: 45.79 min, resulting in an oil extraction yield of 63.48%. For verification purposes, experiments were conducted using the same optimized values of the investigated parameters which resulted in the average oil yield of 63.27% and this prove the reliability of the regression model. The extracted oil’s fatty acid composition was obtained using a gas chromatograph (GC) equipped with flame-ionization detection (FID). The low acid value of the extracted oil is another interesting finding. This is important because it circumvents pretreatment processes such as degumming and esterification prior to the transesterification process. Biodiesel was produced from the oil via ultrasound-assisted transesterification, with a yield of 95.2%. Physiochemical properties of the C. odontophyllum biodiesel were determined, and it was found that all the tested properties comply with fuel specifications based on ASTM D6751 and EN 14214 standards. Significant savings of 52.3% and 80.9% in energy consumption and extraction time, respectively were achieved via ultrasound-assisted extraction compared with the conventional Soxhlet extraction. This study establishes the foundation and the need to further explore the usage of C. odontophyllum as a potential feedstock for biodiesel production.

Simultaneous esterification and transesterification of waste phoenix seed oil with a high free fatty acid content using a free lipase catalyst to prepare biodiesel

Biodiesel is a typical renewable and green energy, that is usually produced by the transesterification of edible vegetable oils. However, the cost of edible vegetable oils as feedstock accounts for 60%–80% of the total cost of biodiesel production. To overcome these issues, in this work, a low-cost feedstock, waste phoenix seed oil (PSO) with a high free fatty acid (FFA) content (30.1 ± 0.6%), consisting of the main fatty acid, linoleic acid (30.2%), oleic acid (22.2%), and palmitic acid (17.4%), was developed as a new feedstock to prepare biodiesel. A novel one-step method including simultaneous esterification of FFAs and transesterification of the PSO to prepare biodiesel was developed. Free lipase was used as catalyst. The influences of the reaction parameters were explored and optimized by response surface methodology. The results showed that the free lipase Lipozyme TL100L from Thermomyces lanuginosus can simultaneously catalyze esterification and transesterification. Under the optimum conditions (enzyme load 9.7%, reaction time 6.9 h, reaction temperature 31 °C and substrate ratio (methanol/PSO) 4.3: 1 (mol/mol)), the maximum biodiesel yield (93.8 ± 0.5%) was achieved. The activation energy from biodiesel preparation using PSO with a high FFA content was 39.7 kJ/mol. Furthermore, the kinetic values for K'm and Vmax were 0.18 mol/L and 0.043 mol/(L·min), respectively. The reaction mechanism of the simultaneous esterification and transesterification was also proposed. These results indicate that PSO with a high FFA content can be used as a potential feedstock for biodiesel production.

LyondellBasell will build a chemical recycling facility

Constant increase in energy demand has necessitated exploration of renewable and sustainable alternative sources of energy. Oleaginous yeast can serve as a potential feedstock for biodiesel production and the recovered de-oiled biomass can be used for production of energy-dense bio-crude by hydrothermal liquefaction (HTL), a precursor for advanced bio-fuels. Life cycle assessment (LCA) of yeast based biofuel production is of existing and must be performed to gauge the possible environmental impacts and obtain a holistic picture. Accordingly, a detailed LCA study encompassing all the sub-processes in biodiesel and bio-crude production in a yeast biorefinery model was executed. Combined analysis of the mid-point and end-point indicators revealed that HTL and transesterification have comparatively higher impacts than the other sub-processes. Climate change indicator results show an emission of 4.02E3 kg CO2 eq. for HTL step and resource depletion for transesterification was estimated to be $773. The major reason for the impacts can be attributed to the usage of large amount of input energy/electricity for both the processes. The use of solvents, namely, methanol and glycerol in various downstream processing steps have contributed to around 60–70% towards the impact categories. Sensitivity analysis revealed higher lipid productivity can reduce CO2 emissions by 16% and resource depletion by 6.5%. The environmental performance of the process can be improved by replacing the electricity from fossil fuel with renewable energy sources such as solar or hydroelectric power with simultaneous recycling and reuse of the solvents and waste heat.

Fatty Acid Methyl Esters from the Herbal Industry Wastes as a Potential Feedstock for Biodiesel Production

Due to thegrowing awareness of fossil fuel depletion and environmental issues, biodiesel alternative fuel is currently of substantial interest. This research assessed herbal industry wastes as a potential resource for biodiesel production for the first time. Fatty acid methyl esters (FAMEs), obtained in the transesterification reaction, were extracted from the herbal samples by ultrasound-assisted extraction and identified withgas chromatography-mass spectrometry in the selected ion monitoring mode. The presence of at least 20 (e.g., in chamomile and chicory) FAMEs, up to 31 in nettle and senna, was reported. The unsaturated FAMEs were found in higher amounts than saturated. Linoleic acidwas the major polyunsaturated FAME in herbal wastes, while palmitic acid was the major saturated FAME. The highest content of FAMEs was identified in rye bran, Figure tea, and chicory. According to the cetane number prediction, BS EN 14214:2012+A2:2019, and hierarchical clustering on principal components (HCPC)wastes from, e.g., nettle, sage, and senna, are the most suitable in biodiesel production with fuel properties acceptable by the EuropeanStandards.Principal component analysis and HCPC allowed to classify and groupsimilar plants according to their FAMEs content; however, additional studies of herbal biofuel properties are needed.

Environmental impact analysis of oleaginous yeast based biodiesel and bio-crude production by life cycle assessment

Constant increase in energy demand has necessitated exploration of renewable and sustainable alternative sources of energy. Oleaginous yeast can serve as a potential feedstock for biodiesel production and the recovered de-oiled biomass can be used for production of energy-dense bio-crude by hydrothermal liquefaction (HTL), a precursor for advanced bio-fuels. Life cycle assessment (LCA) of yeast based biofuel production is of existing and must be performed to gauge the possible environmental impacts and obtain a holistic picture. Accordingly, a detailed LCA study encompassing all the sub-processes in biodiesel and bio-crude production in a yeast biorefinery model was executed. Combined analysis of the mid-point and end-point indicators revealed that HTL and transesterification have comparatively higher impacts than the other sub-processes. Climate change indicator results show an emission of 4.02E3 kg CO2 eq. for HTL step and resource depletion for transesterification was estimated to be $773. The major reason for the impacts can be attributed to the usage of large amount of input energy/electricity for both the processes. The use of solvents, namely, methanol and glycerol in various downstream processing steps have contributed to around 60–70% towards the impact categories. Sensitivity analysis revealed higher lipid productivity can reduce CO2 emissions by 16% and resource depletion by 6.5%. The environmental performance of the process can be improved by replacing the electricity from fossil fuel with renewable energy sources such as solar or hydroelectric power with simultaneous recycling and reuse of the solvents and waste heat.

High density cultivation of oleaginous yeast isolates in ‘mandi’ waste for enhanced lipid production using sugarcane molasses as feed

This study focuses on the use of synthetic and low cost carbon sources for enhanced biomass and lipid production from oleaginous yeast strains using batch and fed batch fermentation. Five strains were selected out of 20 strains which were all isolated from various habitats, on the basis of lipid accumulating potential using Sudan B black dye. The selected isolates were characterized and their lipid production was optimized by batch cultivation in waste extract. Gas chromatography analysis revealed that lipids from all isolated yeast strains contained mainly long-chain fatty acids such as oleic acid, palmitic acid, stearic acid and linoleic acid. On the basis of lipid profile and production, two most suitable oleaginous yeast strains were selected for further experiments, i.e. fed batch fermentation using glucose (control) and sugarcane molasses as feed. Using glucose as feed, 38.8 ± 0.9 g/L and 29.4 ± 0.2 g/L biomass dry cell weight (DCW) and total lipids were produced respectively, whereas with sugarcane molasses feed, 50 ± 1 g/L (DCW) biomass and 39.2 ± 0.6 g/L lipids were produced by Rhodosporidium toruloides ATCC204091. After transesterification the lipid profile was analyzed by GC–MS revealing suitability for use as a potential feedstock for biodiesel production.

Biodiesel production and characterisation of poppy (Papaver somniferum L.) seed oil methyl ester as a source of 2nd generation biodiesel feedstock

One of the challenging tasks for the researchers is to identify alternative renewable energy feedstocks which can be used as a substitute for fossil fuel to meet the increasing demand for energy, reduce the depletion of fossil fuel reserves and eliminate the increasing concerns of environmental impact. The 2nd generation poppy (Papaver somniferum) seed oil (PSO) can be considered as one of the feedstocks which would be low cost and does not compete with food crops for biodiesel production. In this study, biodiesel production was conducted in 2 stage processes which consist of acid and base–catalysed esterification and transesterification to reduce the free fatty acid (FFA) content of poppy seed oil (PSO) and to increase the yield of poppy seed oil methyl ester (PSOME), respectively. To determine the maximum yield of methyl ester, different parameters that influence the production of methyl ester, namely the molar ratio of methanol to oil (5.0:1–7.0:1), catalyst loading (0.5–1.5 wt.%), reaction temperature (40–80 °C) and time (60–120 min) were investigated under the transesterification reaction. The results found that methanol to oil molar ratio of 6.0:1, catalyst loading of 1.0 (wt.%), reaction temperature of 60 °C and reaction time of 90 min were observed to be the optimum process parameters for maximising the yield of PSOME at a constant speed of 720 rpm. In these conditions, the maximum methyl ester yield was found to be about 93 %. The gas chromatography (GC) analysis was conducted to evaluate the fatty acid methyl ester (FAME) composition of the PSOME. Furthermore, the physico-chemical properties of the PSOME were evaluated and characterised using ASTM and EN standards for biodiesel. It was found that PSO can be used as a potential feedstock for biodiesel production as most of the physico-chemical properties are within the ASTM and EN standards.

The effect of stress environment towards lipid accumulation in microalgae after harvesting

Microalgae have been recognized as a potential feedstock for biodiesel production due to their fast growth rate and ability to accumulate lipid within their cells. However, high lipid content and biomass productivity are usually difficult to achieve simultaneously. Instead of stressing the microalgae during cultivation stage, the stress environment such as nutrient starvation, salinity and light effect were introduced to Chlorella vulgaris after harvesting to study the effect on their lipid content. From the results attained, one day of nutrient starvation with 6.0 g/L of salinity stress under dark room condition had shown the highest lipid content of 38.8% (dry weight basis). The lipid content was recorded at 40.28% (dry weight basis) when the working volume was scaled up. In addition, the fatty acids identified in the extracted microalgae lipid were mainly consisted of linoleic, linolenic and palmitic acid, which were commonly found in corn oil, soybean oil and sunflower oil.

Physicochemical Properties of Biodiesel Synthesised from Grape Seed, Philippine Tung, Kesambi, and Palm Oils

The production of biodiesel using vegetable oil is an effective way to meet growing energy demands, which could potentially reduce the dependency on fossil fuels. The aim of this study was to evaluate grape seed (Vitis vinifera), Philippine tung (Reutealis trisperma), and kesambi (Schleichera oleosa) oils as potential feedstocks for biodiesel production to meet this demand. Firstly, biodiesels from these oils were produced and then their fatty acid methyl ester profiles and physicochemical properties were evaluated and compared with palm biodiesel. The results showed that the biodiesel produced from grape seed oil possessed the highest oxidation stability of 4.62 h. On the other hand, poor oxidation stability was observed for Philippine tung biodiesel at 2.47 h. The poor properties of Philippine tung biodiesel can be attributed to the presence of α-elaeostearic fatty acid. Furthermore, synthetic antioxidants (pyrogallol) and diesel were used to improve the oxidation stability. The 0.2 wt.% concentration of pyrogallol antioxidant could increase the oxidation stability of grape seed biodiesel to 6.24 h, while for kesambi and Philippine tung, biodiesels at higher concentrations of 0.3% and 0.4 wt.%, respectively, were needed to meet the minimum limit of 8 h. The blending of biodiesel with fossil diesel at different ratios can also increase the oxidation stability.

A Short Review on Valorization of Slaughterhouse Wastes for Biodiesel Production

AbstractIn recent years, the waste animal fats are drawing attention as potential feedstocks for biodiesel production. The exploit of rendered waste animal fats as feedstocks could help to further decrease the price of biodiesel compared to other feedstocks. These fatty wastes can be transformed into ethyl or methyl esters by the esterification and/or transesterification process with the aid of different types of catalysts. In this outlook, an endeavor has been made in this work to describe the significance of fatty wastes of chicken, fish, beef, goat, sheep, pig and duck in the biodiesel production process. This study also extends to present the distinct techniques used by researchers to convert these fatty wastes into biodiesel.

Biodiesel Production from Insects: From Organic Waste to Renewable Energy

The conversion of organic wastes into biodiesel has become an attractive solution to address waste surplus problems and energy depletion. Oleaginous insects can degrade various organic wastes to accumulate fat-based biomass, thus serving as a potential feedstock for biodiesel production. Therefore, the use of insects fed on organic waste for biodiesel production has increasingly attracted considerable investigations. In recent years, different insect species have been studied for their efficiency in converting various organic wastes and for producing biodiesel from their fat. Several methods have been developed for biodiesel production from insects to improve yields and reduce production costs and environmental impacts. This review summarizes the latest findings of the use of insects for converting organic wastes into biodiesel. The production processes and fuel properties of biodiesel produced from insects are also discussed.

Biodiesel production from Halamphora coffeaeformis microalga oil by supercritical ethanol transesterification

The marine benthic diatom Halamphora coffeaeformis is a potential feedstock for biodiesel production. This species shows high growth rates, important triacylglycerol (TAG) contents and grows in seawater making large-scale cultivation advantageous. Moreover, sustainable biofuel production in future biorefineries requires the implementation of technologies that employ renewable solvents. Thus, the goal of this work was to evaluate ethanol usage as extraction solvent and reaction medium for biodiesel production from H. coffeaeformis. In a first step a bio-oil extraction was carried out comparing ethanol and n-hexane to investigate the performance of ethanol with respect to a conventional solvent. Then, a free-catalyst supercritical ethanol transesterification of the bio-oils was carried out to obtain biodiesel. Higher lipid extraction yields were obtained using ethanol respect to n-hexane (26 wt.% vs 21.1 wt.%). The transesterification of crude lipids extracted with ethanol as solvent at 305 °C and 40 min. produced up to 15.9 wt.% of biodiesel respect to dried biomass processed. Comparable biodiesel yields were obtained using non-renewable organic solvents and a conventional catalytic technology. Thus, ethanol extraction and subsequent supercritical transesterification of H. coffeaeformis oil proved to be technically feasible and environmental friendly technology for the production of biodiesel.