---

Research subject: Iran is a country with high potentials for access to renewable energy sources such as solar, hydropower, wind, and biomass. Biodiesel is one of the renewable fuels that has always been proposed as a suitable and stable alternative (non-toxic, safe, and degradable) to fossil fuels.
Research approach: The experiences of different countries in the use of edible sources for biodiesel production shows that the use of edible sources has caused problems such as lack of food resources for human communities, lack of feed for livestock, and upsetting the balance in the food industry, and it can lead to a significant increase in the price of these resources. Therefore, many researchers have proposed the use of non-edible sources to address these problems. So far, very large non-edible sources for biodiesel production have been identified. In this paper, non-edible sources of biodiesel that are produced or have the potential to be produced in Iran are introduced and studied and a potential assessment study is presented for them.
Main results: In this work, the non-edible sources for biodiesel production are classified into four categories: agricultural waste, waste cooking oils, microalgae, and non-edible seeds. These sources are compared based on various parameters such as oil percentage, oil content per hectare, biodiesel production efficiency, viscosity, saponification number, and cultivation period, which according to the results, non-edible seeds, especially Nowruzak seeds, Castor, and safflower have been identified as the most rational and sustainable sources of biodiesel production in Iran. The present work also deals with the policies and incentives that the responsible institutions can apply for the prosperity of the biodiesel industry.

---

Research subject: Nowadays, due to the prevalence of coronavirus and the increasing use of disinfectant solutions and gels, the use of glycerin has also increased dramatically. But the suggested processes in this field need to be optimized in terms of production and energy consumption.

Research approach: In this paper, the transesterification method has studied and simulated, during which vegetable oil is converted into biofuel, and glycerin is also produced as a by-product of this process. For this purpose, process simulation of a conventional unit with 5.5 m³/min feed has been done in Hysys. Also, due to the importance of equipping the transesterification reactor, by importing the necessary process information, this equipment has been simulated in COMSOL MultiPhysics and the effective parameters have been studied in order to optimize the of product conversion. After validation of model, to better understand the factors affecting the performance of the transesterification reactor, the effect of selected parameters first examined by one-variable at the time design of experiment approach.
Main result: Finally, it has been shown that the feed temperature and the flowrate both have significance impact on quantity and quality of product and while providing a model for calculating the amount of glycerol produced per unit of energy consumed, the effective parameters are optimized by the response surface method. In optimal conditions of the ratio of product production to energy consumption, the temperature value was 470.7 K and the feed flow rate was 0.586 m³/s. According to the gained results, it can be obtained by adjusting the flow rate in the optimal amount, using a preheater in the production processes of biofuels and glycerin can have a significant effect on the amount of products produced so that the optimal temperature for the output of this preheater is at least 470.7 K should be considered. In the current research an optimization scheme has been suggested which can be used for different Biodiesel-Glycerol production units with varies range of flowrate.
 

---

Biodiesel as a clean fuel is renewable, biocompatible and free of polycyclic aromatic hydrocarbons that could be deriving from animals, plants, fungal, algae and bacteria resources. Among these resources, oleaginous fungi due to the high capability to synthesize and accumulation of triacylglycerol are the best source for biodiesel producer. So, in order to providing approaches for increase biodiesel production based on biotechnology, molecular investigation in these organisms could be promising approach, which have been attentioned in this study. In this regard, a precise survey on the related molecular mechanisms led to reveal Malic enzymes as the effective and critical proteins in lipids production and accumulation in oleaginous fungi. Structural characterization of the genes, led to reveal that they are different in the length and GC content as well as they are continuous in the sequence context. Moreover, structural characterization of the enzymes led to determine their localization in the cells, present the functional domains with capability of post-translational modifications in all of them, which are including MAO1_MF, Malic_M and malic. Homologous sequences survey of the enzymes led to introducing fungal species with possible capability for lipid production.structural modeling of the selective malic and malic like enzymes led to provided suitable models in structure and quality in function with binding affinity to malate. In general, the results of this study, while introducing suitable fungal species for securance of biomass, led to reveal effective enzymes with special features that could be useful in tracing the capable strains or transgenesis modification.

---

Introduction: Biofuel production from renewable resource has been extensively paid attention as a sustainable alternative for fossil fuel. As the feed of third-generation biofuels, microalgae can produce variety of lipids, proteins, and carbohydrates in large quantities and in a relatively short time. Regarding the compatibility of these microorganisms with culture diffrent conditions and independence from the seasons of the year, the rapid growth rate, absorbing carbon dioxide and improving air quality, renewablity, non-competing with food supplies, the existence of large quantities of lipid and carbohydrate inside their cells, and abillity of biofuels production, microalgae are known as one of the most suitable options for the biofuels production. Biofuel production from microalgae consists of several stages, including cultivation, harvesting, drying, cell disruption, extraction (lipids or carbohydrates), and the production of biofuels.
Conclusion: In the present study, by reviewing each stage of the biofuels production from microalgae, its importance and application for bioenergy production is discussed. Algal biofuel is not yet competitive with fossil fuels due to its high costs. Researchers are trying to produce economic algal biofuel by improving the growth of microalgae and enriching their reserves of oil and carbohydrates, creating genetic changes, improving the design of photobioreactros, developing harvesting and drying methods, improving methods of extracting lipid and carbohydrate, and producing valuable products.

---

Biofuels are the main substitute to fossil fuels. These fuels are less polluting in compari-son to fossil fuels and can be produced from agricultural material residues for use in die-sel engines. In this research work bioethanol was produced from potato waste. It was de-hydrated in a vapor phase using 3A zeolite and was used in combination with sunflower methyl ester oil and diesel fuel blending which was evaluated thereafter. The sunflower methyl ester was also produced using a transesterification method. Considering the labo-ratory conditions and fuel stability limits to be used, the suitable blending proportion of bioethanol and diesel fuel was determined to be 12 to 88 and then, for maintaining fuel stability at temperatures lower than 15oC, the sunflower methyl ester was added to the mixture. The pour point of the fuel and different fuel blends, the viscosity, cetane number, flash point, amount of fuel ash, sulfur content and copper corrosion were determined in the laboratory. Experiments show that ethanol plays an important role on the flash point of the blends. With the addition of 3% bioethanol to diesel and sunflower methyl ester, the flash point was reduced to 16oC. The viscosity of the blends was reduced with the in-crease in the amount of ethanol. The sulfur content of bioethanol and sunflower methyl ester is very low compared with that of diesel fuel. The sulfur content of diesel is 500 ppm whereas that for ethanol and sunflower methyl ester is 0 and 15 ppm, respectively. The lower amount of sulfur content facilitates the use of fuel blends in diesel engines. For the ethanol and sunflower methyl ester combination, this amount is less than 20 ppm.

---

  
Objectives: In this study, the effect of different concentrations (1-50 mg/L) of colloidal Ag-NPs investigated on the growth, fatty acids profile and biodiesel indices of N. oculata, after estimating EC50 (20.88 mg/L).
Materials and methods: In this research, N. oculata was selected owing to fast growth and its ability to synthesize lipids for biodiesel production. This microalga exposed to colloidal silver nanoparticles under marine conditions for 72 h. The optical density (OD) and fatty acid profiles were investigated using spectrophotometric analysis and gas chromatography, respectively. Statistical analysis growth data was performed using ANOVA and Duncan's multiple test at 2% probability level.
Results: The algal growth significantly decreased in N. oculata cells treated with the 5-50 mg/L of Ag-NPs.  The increase of saturated fatty acids (SFAs) and polyunsaturated fatty acids (PUFAs) as well as the decrease of monounsaturated fatty acids (MUFAs) contents were also observed in response to 25 mg/L of Ag-NPs in compared to the control. The important indicators of biodiesel oxidative stability containing LCSF, CFPP and CP increased in N. oculata exposed to Ag-NPs, while the level of DU decreased. The results of this study showed that despite the toxicity of silver nanoparticles, this nanoparticle can increase the biodiesel stability produced from N. oculata.
 

---

In this research work, a comprehensive combustion analysis has been conducted to evaluate the performance of a low speed diesel engine (M8/1 Lister) using biodiesel fuel. Waste vegetable cooking oil as an alternative fuel. Biodiesel obtained from waste vegetable cooking oil (WCO) as an alternative fuel. The properties of biodiesel produced from WCO was measured based on ASTM standards. In order to compare brake power, torques , brake specific fuel consumption (BSFC) and concentration of the UHC and CO emissions of the engine, it has been tested under same load of Dynamometer(5 levels) and biodiesel fuel blends (levels)) at constant engine speed(750 rpm). The results were found to be very comparable. An artificial neural network (ANN) was developed based on the collected data of this work. Multi layer perceptron network (MLP) was used for nonlinear mapping between the input and the output parameters. Different activation functions and several rules were used to assess the percentage error between the desired and the predicted values. The results showed that the training algorithm of Back Propagation was sufficient in predicting the engine torque, brake power, specific fuel consumption and exhaust gas components for different engine loads and different fuel blends ratios.

---

Biodiesel fuel, which is produced by transesterification reaction between alcohol and vegetable oil/animal fat is proposed as a clean alternative to petro diesel fuel. Today, one of the new technologies to produce biodiesel is using ultrasonic energy that makes production faster, with improved quality and less expensive. Various factors that affect the design of ultrasonic reactors are ratio of vibrating rod diameter to reactor diameter, reactor height, depth of horn penetration into fluid and chamber characteristics (material and shape). In this paper, two parameters namely the ratio of vibrating rod diameter to reactor diameter and reactor height were studied in order to increase the reaction efficiency. In all performed tests, the horn diameter of 14 mm, molar ratio of alcohol to oil of 5 to 1, catalyst concentration of 0.7% wt?? oil, depth of horn penetration into fluid of 15 mm and a cylindrical reactor were used. Experimental design involved the use of Central Composite Design (CCD) and the statistical Response Surface Methodology (RSM). Considering the empirical model, a significant relationship was found between independent and dependent variables with a regression coefficient of 0.99. Taking into account the desirability of increasing the efficiency, the optimal function of reactor diameter and reactor height were 63 and 110 mm, respectively with a reaction yield of 87%. In order to verify the model, function responses in the defined area were tested with five replicates and the average efficiency of the reaction was 87.2%. The obtained model suggests the simultaneous reverse effects of reactor diameter and height on the reaction efficiency.

---

Biodiesel is a renewable fuel that can be produced from vegetable or animal oil. The main benefit of using biodiesel is its capacity to lower exhaust emissions compared to diesel fuel. Over the last few years, numerous studies have been performed on biodiesel production and its effect to engine performance and emissions. However, in those studies; no attention has been paid in economic analysis of biodiesel usage in engines. In this investigation, various mixtures of biodiesel and diesel fuel have been tested on a four cylinders turbocharged diesel engine. The combustion reaction was determined by using the experimental data. Then, the mass flow rate of each exhaust emissions was calculated, using combustion reaction. The economic analysis was performed considering social cost of emissions, inlet fuel cost and the cost of engine power loss. Because of low diesel fuel price in Iran, the results were determined by ignoring the inlet fuel cost. The technical analysis was also performed considering the engine performance results. The results showed that the 10% and 15% biodiesel-diesel blends (B10 and B15) were more affordable than diesel fuel. The performance results of engine were also acceptable in these blends. The power loss was slight and the highest thermal efficiency was also observed in these blends. All biodiesel blends were more affordable than diesel in emissions economic analysis

---

One of the important bottle-necks in production of microalgae based biodiesel is the lack of an efficient method for harvesting of microalgae from the culture medium. In this study, the electroflocculation method was developed for harvesting of microalgae Dunaliella cells from culture medium. The effect of several parameters such as the current density, electrical conductivity of culture medium, time, electrode gap, and electrode type on harvesting efficiency and energy consumption were also determined. The maximum harvesting efficiency of this method was 97.44% at EC= 1.35 S m-1 and current density of 90 A m-2 during 3 minutes electroflocculation process in a 300 ml beaker. The maximum efficiency was achieved by aluminum electrodes with 1 cm distance between electrodes and the maximum energy consumption for this practice was 0.621 kW h m-3. It was concluded that electroflocculation is an efficient and cost effective method for microalgae harvesting.

---

Biodiesel is a renewable and sustainable alternative fuel that is derived from vegetable oils and animal fats. In this paper an experimental investigation is conducted to evaluate the use of soybean oil methyl ester (biodiesel) in the diesel fuel at blend ratios of B0, B2, B5 and B10. In this study, the performance and emissions characteristics of conventional diesel fuel and biodiesel fuel blends were compared. The tests were performed at steady-state conditions in a direct injection diesel engine with 90 kW power that was equipped with EGR and with no modification of calibration. The experimental results of brake-specific fuel consumption (BSFC), torque and exhaust temperature as well as carbon dioxide (CO2), smoke, nitrogen oxide (NOx), carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions were presented and discussed. The results of engine performance parameters at different conditions (different load and engine speed) showed that a negligible loss of engine power and a significant increase in brake specific fuel consumption due to lower heating value of biodiesel. Smoke, CO and HC emissions were decreased by increasing blends of soybean oil as compared to pure diesel. However the increase in engine NOx and CO2 emissions were observed with the increase of biodiesel percentage in the blended fuel.

---

In this study evaporation of biodiesel droplet under different operating conditions is investigated. The model is a common droplet vaporization model for multicomponent fuels. In this model, gas phase quasi-steady equations are solved analytically and energy and species transport equation in liquid phase are solved numerically. The sub-models are modified to consider high pressure effects. Peng-Robinson equation of state is used for gas phase and phase equilibrium is determined using fugacity. Effects of pressure on the thermophysical and transport properties of gas phase are considered. Five biodiesel with different composition are studied. These biodiesel have different composition of methyl esters. Biodiesel composition has little effects on droplet lifetime and maximum difference is about 20%. It is observed that increasing ambient temperature leads to decrease in droplet lifetime and increases temperature gradient inside droplet. Ambient pressure has different effects on droplet vaporization behavior at different ambient temperature. At lower temperature environment, increasing of pressure increases the droplet lifetime while at higher temperatures droplet lifetime first increases and then decreases with pressure. Increasing initial velocity of droplet reduces the droplet lifetime. Results show that at high pressures, droplet temperature reach to values near to critical temperature and accuracy of quasi-steady approximation decreases. Radius of vapor influenced sphere increases with temperature and decreases with pressure.

---

In recent years, coinciding with the expansion of biofuel production, attempts have also been made to optimize production processes. In this study, Response Surface Methodology (RSM) was used to investigation the transesterification reaction of rapeseed oil for biodiesel production. Three main factors in order to convert triglycerides into fatty acid methyl esters (FAME) were applied according to a central composite design. These factors were catalyst concentration (NaOH), reaction temperature and time. The yield of methyl ester as the first response was determined using NMR method. The second response was the commercial cost of production. The results showed that the best conditions for producing biodiesel in constant the molar ratio of 1: 6 oil: methanol were the temperature of 47.27 oC, NaOH concentration of 1.24 %wt/wt and reaction time of 30 min. At these optimum conditions, the yield of methyl ester and cost of production is 77.67% and 67 ¢, respectively. Also, some chemical and physical properties of biodiesel were compared with petro-diesel fuel. According to the results, biodiesel fuel is a suitable substitute for petro-diesel fuel.

---

---

One of the major problems in the world is the supply of energy. Biodiesel is one of the alternative fuels and renewable energy sources. The use of B₅ biodiesel in diesel fuel mixtures is common and most countries have planned to use B₂₀ biodiesel. The use of natural gas in diesel engines and the study of the possibility of using it in high quantities is another new solution, which can reduce dependence on diesel fuel. In this study, biodiesel was produced from waste oil by transesterification process and used in two levels of 5 and 20% in diesel composition. Then natural gas was used in three levels of 60, 70, and 80% (% G / T) in the diesel engine. Engine tests were performed at full-load at 1500 rpm. In general, the test results showed that in conditions where biodiesel B₂₀ was used in the composition of diesel fuel and gaseous fuel was used in the amount of 80% in a diesel engine, suitable conditions in terms of reducing emissions, increasing energy efficiency, and reducing economic costs were obtained; Under these conditions, compared to a conventional diesel engine, brake power, and energy efficiency increased by 8.86 and 29.06%, respectively. Also, brake specific fuel consumption, CO and CO₂ were reduced by 26.5, 57.58, and 4.54%, respectively. Although the amount of NOx increased slightly, but, decreased the economic cost compared to diesel 26.47% $/kwh, so the results were valuable.