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Biodiesel is the most promising bio-based alternative to the large quantity of fossil diesel fuel used in the transportation sectors. However, its corrosive behavior when in contact with the diesel engine and fuel system components is of serious concern. The present work comprehensively reviews the impacts of biodiesel on the corrosion behavior of metal-based parts in diesel engines such as copper and copper-based alloys, aluminum and aluminum-based alloys, cast iron, carbon steel, and stainless steel. The corrosion mechanisms of the mentioned metals in biodiesel are also presented and discussed in detail. Methods applied to study the corrosion phenomenon and its level are also presented. The reasons leading to the higher corrosiveness of biodiesel vs. diesel fuel, including its higher hygroscopicity, higher electrical conductivity, higher polarity, higher solvency, the presence of water and oxygen in biodiesel promoting microbial growth, and finally, its auto-oxidation resulting in the generation of corrosive agents, i.e., monocarboxylic acids, are also detailed. Finally, the use of corrosion inhibitors in biodiesel to enhance metals/alloys resistance to corrosion is reviewed. Future research needs to further expand biodiesel utilization worldwide are also envisioned. [ABSTRACT FROM AUTHOR]

The present study provides firstly a comprehensive review of studies on measuring the impacts of different biodiesel blends on exhaust emissions characteristics of urban busses under real-world operating conditions. Secondly, this paper discusses the errors that can be made in conducting case studies. Thirdly and finally, it shows lessons learned and provides guidelines to setup case studies, conduct the measurements, perform the statistical analysis and report the results to policy makers and the wider audience. To achieve climate change mitigation targets, using alternative fuels, e.g., biodiesel, hydrogen or electricty (EVs) for the urban fleets requires an in-depth analysis of the impacts under real-world operating conditions. Such experiments are generally very complex as numerous factors could directly or indirectly interfere with the results produced and potentially jeopardize the integrity of the research and the conclusions drawn. Results of the present research show that some vital parameters were ignored by many of the studies performed including the statistical uncertainties, driving cycle uncertainties and fuel uncertainties. Lack of appropriate experimental designs or clear assertions about the level of significance for differences in emissions/fuel consumption between alternative fuels (i.e. biodiesel) and the reference fuel used (i.e., diesel) could be regarded as the main weaknesses. Moreover, many other overarching and very influential factors (e.g., covariates/confounders) can interfere with the research outcomes as these were mostly overlooked by the reviewed studies. A careful and complete experimental design for assessments of alternative fueled vehicles (are critical when conducting real-world operating condition tests. The study findings help to formulate the guidelines for assessing real-world operating condition experiments to achieve the most feasibly and meaningful research outcomes that will have significant implication for local and global policy makers. The guidelines are of use for all types of research studies that want to evaluate the effects of alternative fuels for any transportation fleet. Image 1 • Real-world driving tests on urban buses were examined and discussed. • Key issues were uncertainties related to statistical design, driving cycle, and fuel. • Lack of appropriate experimental design was the main weakness in most studies. • Covariate/confounder factors were mostly overlooked. • Guidelines to perform more complete real-world diving test studies were presented. [ABSTRACT FROM AUTHOR]

• Transesterification reactors for biodiesel production are comprehensively reviewed. • The effects of the main parameters on the transesterification process are scrutinized. • Pros and cons of each reactor technology for biodiesel production are outlined. • The sustainability aspects of biodiesel production are comprehensively discussed. • Policy and economic aspects of biodiesel have been extensively securitized. Diesel engines are preferred over spark ignition counterparts for heavy-duty applications and power generation plants because of their higher efficiency, durability, and productivity. Currently, the research interests have been propelled towards renewable and sustainable diesel fuels such as biodiesel in order to address the environmental and energy security challenges associated with these energy systems. However, the most challenging issue concerning large-scale production of biodiesel is its relatively high cost over fossil-based diesel owing to high feedstock and manufacturing costs. Therefore, cost-effective and eco-friendly biodiesel production technologies should be necessarily developed and continuously improved in order to make this biofuel more competitive vs. its petroleum counterpart. Accordingly, this paper comprehensively reviews biodiesel manufacturing techniques from natural oils and fats using conventional and advanced technologies with an in-depth state-of-the-art focus on the utmost important unit, i.e., transesterification reactor. The effects of the main influential parameters on the transesterification process are first discussed in detail in order to better understand the mechanisms behind each reactor technology. Different transesterification reactors; e.g. , tubular/plug-flow reactors, rotating reactors, simultaneous reaction-separation reactors, cavitational reactors, and microwave reactors are then scrutinized from the scientific and practical viewpoints. Merits and limitations of each reactor technology for biodiesel production are highlighted to guide future R&D on this topic. At the end of the paper, the sustainability aspects of biodiesel production are comprehensively discussed by emphasizing on the biorefinery concept utilizing waste-oriented oils. [ABSTRACT FROM AUTHOR]

Global application of biodiesel in the transport sector has rapidly expanded over the last decade, however, efforts to overcome its main shortcoming, i.e., increase in NO x emissions compared with diesel, are still underway. In light of that, parameters/strategies capable of mitigating biodiesel NO x emissions are of wide interest to further enhance the sustainability aspects of this green fuel. Among various options put to test, the use of fuel additives due to its simplicity and cost-effectiveness has attracted a great deal of attention. In this study, the mechanical shaft work produced by a diesel engine fueled with various diesel/biodiesel blends (B5 and B20) containing glycerol-derived triacetin was scrutinized from environmental viewpoint. Neat petro-diesel, B5, and B20 were also considered as control fuels. Two environmental evaluation methodologies, namely discrete emissions analysis and consolidated life cycle assessment (LCA) were considered to assess the impacts of fuel composition, engine speed, and engine load on the environmental burdens of the shaft work produced. According to the results obtained, the outcomes of both methods considered herein were profoundly affected by engine load and speed. Even though triacetin inclusion into both B5 and B20 profoundly affected the outcomes of emissions analysis, its application did not lead to any spectacular differences in the results of LCA method compared with petro-diesel. More specifically, triacetin incorporation into fuel blends neutralized the unfavorable impacts of biodiesel addition in terms of NO x emissions. However, incorporating triacetin into diesel/biodiesel blends in general did not profoundly mitigate the environmental impacts of the shaft work produced in terms of LCA damage categories as well as the total environmental impacts. Overall, using triacetin as combustion improving agent did appear to be an efficient strategy from the LCA viewpoint considering the current production technologies. In addition, LCA approach was found to be more a comprehensive decision-making approach compared with discrete emissions analysis for evaluating the environmental impacts of the shaft work produced by internal combustion engines. • Triacetin inclusion into diesel/biodiesel blends was environmentally scrutinized. • Triacetin mitigated CO, NOx, and PM emissions while increased CO 2 emissions of fuels. • HC emissions were not clearly affected by triacetin addition into fuel blends. • Triacetin compensated for unfavorable impact of biodiesel in terms of NO x emissions. • LCA was found to be comprehensive decision-making approach over emission analysis. [ABSTRACT FROM AUTHOR]

Highlights • Effects of various diesel/biodiesel additives comprehensively reviewed & discussed. • Effect of engine operating factors on regulated and nonregulated emissions reviewed. • Research works related to life cycle assessment of biodiesel was reviewed. Abstract Biodiesel, in its neat or blended form with petrodiesel, is widely accepted alternative fuel for diesel engines. Although biodiesel is presumably associated with lower CO 2 , HC, and PMs emissions, it suffers from its own drawbacks including higher viscosity, lower volatility, lower heating value, and higher NO x emissions. In order to address these shortcomings and to meet stringent emission norms, diesel/biodiesel additives have attracted more attention recently owing to their ability to improve engine performance and mitigate hazardous emissions. While discrete emissions analysis could provide useful information on environmental impacts associated with various fuel additives, decision-making on such basis would be very difficult or even impossible since different fuel additives may have different positive/negative effects on pollutants generated during combustion process. This issue becomes even more serious in multi-objective optimization studies due to the fact that considering all emission indices for finding a global optimal point would be very complex as a result of conflicting objectives. Moreover, exhaust gas emission analysis does not consider environmental impacts caused in fuel production process. Discrete emissions analysis also lacks weighting in decision-making procedure since the level and degree of harmfulness of pollutants may not be comparable. Life cycle assessment (LCA) has been recognized as a valuable tool to address these challenges through systematical evaluation of potential environmental impacts of fuel additives. Accordingly, this paper was aimed at comprehensively reviewing and mechanistically discussing the effects of various diesel/biodiesel additives including metal-based, oxygenated, antioxidant, cold flow improver, lubricity improver, and cetane number improver additives as well as engine operating parameters like engine load, engine speed, EGR, and injection timing on both regulated and non-regulated emissions. Moreover, the environmental impacts of various diesel/biodiesel additives by incorporating an LCA approach was also critically discussed. [ABSTRACT FROM AUTHOR]

Biodiesel degradation through autoxidation radical chain reactions adversely affects long-term storage stability, high thermal oxidation stability, and consequently biodiesel consumers’ acceptance. Propyl gallate, the most promising synthetic antioxidant, is widely used to address this challenge. However, the application of this synthetic antioxidant is associated with health concerns such as risk of brain tumors as proposed by the National Toxicology Program (U.S. Department of Health and Human Services). Herein, the application of a naturally-originated alternative to propyl gallate, i.e., pistachio hull extract in canola biodiesel was investigated from technical and environmental viewpoints. According to the results achieved, a concentration of 2500 ppm of the bio-antioxidant and 250 ppm of the synthetic antioxidant was needed to improve the induction period of the investigated biodiesel from 1.53 h to above 3 h as required by ASTM D6751-12 specification for biodiesel oxidation stability. In spite of the fact that the higher concentration of the bio-antioxidant was required, its application would be justified by the probable health hazards of its synthetic counterparts. On the other hand, 23% of the global biodiesel production takes place in top pistachio producing countries where a huge amount of pistachio fresh hulls are generated. Therefore, valorization of this considerable agro-waste stream into a natural antioxidant, i.e., pistachio hull extract, seems to be a promising strategy to enhance the favorable environmental and health aspects of biodiesel. In addition, life cycle assessment revealed that the production and application of the bio-antioxidant were favorable from the climate change and human health perspectives compared with propyl gallate. [ABSTRACT FROM AUTHOR]

In this study, exergoeconomic and exergoenvironmental approaches were applied to evaluate and optimize the performance of a low-energy consumption, high frequency piezoelectric ultrasonic reactor used to synthesize biodiesel from waste cooking oil (WCO). The effects of various process parameters viz. methanol/oil molar ratio (X), transesterification temperature (T), and residence time (t) on the exergoeconomic and exergoenvironmental variables were comprehensively assessed and discussed. The exergoeconomic and exergoenvironmental variables were cost and environmental impact per unit of exergy for the product, relative cost and environmental impact differences, cost and environmental impact associated with exergy destruction, and exergoeconomic and exergoenvironmental factors. An optimization study was also carried out using a coupled scheme of adaptive network-based fuzzy inference system (ANFIS) and non-dominated sorting genetic algorithm-II (NSGA-II). Two more relevant exergy-based variables, i.e., cost and environmental per unit of exergy for the product as objective functions were modeled using the ANFIS approach on the basis of process parameters. The process yield as a threshold function was similarly simulated using the ANFIS approach. The optimum operating conditions of the system were then explored by NSGA-II algorithm through minimizing both objective functions while complying with the ASTM standard on process yield (i.e., conversion efficiency >96.5%). Overall, the process parameters profoundly affected the exergoeconomic and exergoenvironmental variables. Results indicated that the ANFIS approach accurately predicted the objective and threshold functions with an R 2  > 0.99. The optimum operating conditions were: X = 7.4, T = 60 °C, and t = 10 min. Under these conditions, the cost and environmental impact per unit of exergy for the product were respectively found to be 2.23 USD/GJ and 1.32 mPts/GJ, whereas the process yield stood at 96.5% meeting the ASTM standard. In general, exergoeconomic and exergoenvironmental approaches appeared to be promising complements to the conventional exergy analysis for developing thermodynamically, economically, and environmentally conscious biodiesel production systems. [ABSTRACT FROM AUTHOR]

In this work a thermodynamic model was developed to attain enhanced process comprehension of waste cooking oil (WCO) transesterification process in a low power, high frequency piezo-based ultrasound reactor. The reactor performance was assessed using the exergy concept to distinguish the effects of various operational variables, i.e., methanol to oil molar ratio (4:1–8:1), ultrasonic irradiation time (6–10 min), and temperature (40–60 °C) on the efficiency and sustainability factors. The exergetic efficiency of the developed reactor was found to be ranging from 98% to 99% and from 9% to 91% using the universal and functional definitions, respectively. The maximum functional exergetic efficiency as a decision making parameter, was found at 91% for methanol to oil molar ratio of 6:1, ultrasonic irradiation time of 10 min, and temperature of 60 °C. The exergetic sustainability index of the transesterification process at the selected conditions was determined at about 11. Under these conditions, the reactor efficiently converted triglycerides to methyl esters with an acceptable conversion efficiency of 97%, satisfying the ASTM standard. Overall, the outcomes of the current survey manifested that exergy analysis can be a preferred basis for decision making on the efficiency and sustainability of various biodiesel synthesizing systems. [ABSTRACT FROM AUTHOR]

Due to the large amount of diesel fuel demands worldwide and the negative environmental and health impacts of its direct combustion, biodiesel production and consumption have been globally increasing as the best short-term substitute for mineral diesel. However, using edible and non-edible oil feedstocks for biodiesel production has led to several controversial issues including feedstock availability and cost, greenhouse gas (GHG) emission, land use changes (LUC), and fuel vs. food/feed competition. Fortunately, these problems can be effectively overcome using non-crop feedstocks. In this context, waste-oriented oils/fats have been proposed as the excellent options to produce biodiesel by overlooking the trivial collection/recycling costs. In this review article, a comprehensive collection plan followed by an elaborated integrated utilization strategy called "waste oil biodiesel utilization scenario" (WO-BUS) is proposed for Iran in order to achieve cost-effective and eco-friendly production/consumption of biodiesel. WO-BUS is adoptable by the countries with similar situations and infrastructures. [ABSTRACT FROM AUTHOR]

Depletion of fossil fuel resources and stringent emission mandates has spurred the search for improved diesel engines performance and cleaner combustion. One of the best approaches to solve these issues is to use biodiesel/diesel additives. The effects of biodiesel/diesel additives on the performance and emissions of diesel engines were comprehensively reviewed throughout this article. The additives reviewed herein were classified into five categories, i.e., oxygenated additives, metallic and non-metallic based additives, water, antioxidants, and polymeric-based additives. The effects of each category on the engine performance (i.e., brake specific fuel consumption (bsfc) and brake thermal efficiency (bte)) and emissions (i.e., CO, NO x , HC, and PM) were exclusively summarized and discussed. Furthermore, various strategies used for adding water like water-diesel emulsion, direct water injection, and adding water into the inlet manifold were illustrated and their pros and cons were completely scrutinized. Finally, opportunities and limitations of each additive considering both engine performance and combustion benignity were outlined to guide future research and development in the domain. [ABSTRACT FROM AUTHOR]

This study was aimed at synthesizing a novel soluble hybrid nanocatalyst to decrease emissions i.e., nitrogen oxide compounds (NO x ), carbon monoxide (CO), unburned hydrocarbons (HC) and soot, of a DI engine fueled with diesel–biodiesel blends. Moreover, enhancement of performance parameters i.e. power, torque and fuel consumption was also simultaneously targeted. The hybrid nanocatalyst containing cerium oxide on amide-functionalized multiwall carbon nanotubes (MWCNT) was investigated using two types of diesel–biodiesel blends (B5 and B20) at three concentrations (30, 60 and 90 ppm). The results obtained revealed that high surface area of the soluble nano-sized catalyst particles and their proper distribution along with catalytic oxidation reaction resulted in significant overall improvements in the combustion reaction specially in B20 containing 90 ppm of the catalyst B20 (90 ppm) . More specifically, all pollutants i.e., NO x , CO, HC and soot were reduced by up to 18.9%, 38.8%, 71.4% and 26.3%, respectively, in B20 (90 ppm) compared to neat B20. The innovated fuel blend also increased engine performance parameters i.e., power and torque by up to 7.81%, 4.91%, respectively, and decreased fuel consumption by 4.50%. [ABSTRACT FROM AUTHOR]

Abstract: Current biomass sources for energy production in Iran include sewerage as well as agricultural, animal, food industry and municipal solid wastes, and are anticipated to account for about 14% of national energy consumption in near future. However, due to the considerable progress made in genetic engineering of various plants in Iran during the last decade and the great potentials of microalgae for biofuel production, these photosynthetic organisms could be nominated as the future source of bioenergy in Iran. An overview of status of bioenergy in the world and Iran as well as the potential and utilization of biomass in Iran is presented. The possibilities of increasing biofuel production through microalgal genetic engineering and the progress made so far are discussed. Biodiesel in the Iran and its future prospective is also reviewed, emphasizing the promising role of microalgae. [Copyright &y& Elsevier]

The drastic rise in global warming and the fossil fuel consumption have resulted in destruction of the ecological balance, reduction of the environmental quality, and demotion of the sustainable development. The utilization of biofuels have been paid much attention to by researchers and policy makers due to its benefits and indisputable contributions to protect the living environment. Free fatty acid-rich rice bran oil which is unsuitable for food purposes could be a good candidate for biofuel production. Accordingly, rice bran oil-based biofuels (straight oil and its biodiesel) as promising alternative fuels to petrodiesel were reviewed in this article from the sources, components, and physicochemical perspectives. In addition, biodiesel production from rice bran oil using various methods and catalysts was thoroughly detailed. The oxidative stability of rice bran biodiesel as a function of the storage time was also discussed. The application of rice bran oil-based biofuels to diesel engines was completely analyzed and critically discussed based on engine performance, combustion, and emissions characteristics. The effects of using rice bran oil-based biofuels on the lubricating oil degradation, deposit formation, wear, and sound intensity of diesel engines were explained in detail. Finally, the economic aspects of using rice bran oil and its biodiesel as fuels were also assessed. As a conclusion, the blend containing 20% rice bran oil biodiesel and 80% petrodiesel fuel, both in volume, could be the most effective composition considering the techno-economic aspects of diesel engines; meanwhile the remaining blends appeared to be improper for the existing diesel engines. • Various aspects of biofuels from rice bran oil as alternatives to diesel are reviewed. • Biodiesel production from rice bran oil using various methods is analyzed in detail. • The effects of rice bran oil-based biofuels on the behavior of engines are detailed. • The economic aspects of using rice bran oil and its biodiesel as fuels are assessed. • Blending diesel with 20% rice bran oil biodiesel could lead to promising results. [ABSTRACT FROM AUTHOR]

• Doping diesel/biodiesel emulsion fuels with CNP was environmentally studied. • Electricity use was main environmental hotspot in carbon nanoparticles production. • CNP addition led to lowest weighted environmental impacts per GJ shaft work. • Emulsion fuels doped with 150 µM CNP were the most eco-friendly at low engine loads. • Emulsion fuels doped with 38 µM CNP were the most eco-friendly at full engine loads. This study was aimed at consolidating emission indices of a diesel engine powered by carbon nanoparticles (CNP)-doped diesel/biodiesel emulsion fuels using a life cycle assessment (LCA) framework. The effects of fuel chemistry and engine load on the consolidated LCA-based environmental indicators of the engine (i.e., human health, ecosystem quality, climate change, and resource consumption damage categories) were investigated. Mineral diesel was reconstituted by adding 5 wt% biodiesel, 3 wt% water, and various concentrations of the waste-derived aqueous CNP ranging from 38 to 150 μM. Three CNP-free baseline fuels were also used as control. The engine was loaded in the range of 25–100% and at a fixed speed of 1000 rpm. In general, electricity use in the CNP manufacturing process increased all the investigated damage categories for the fuel blends dosed with the nanoadditive. Nevertheless, the lowest weighted environmental impacts per GJ shaft work were also obtained for the CNP-doped emulsified fuels. More specifically, dosing diesel/biodiesel emulsion fuel with 38 and 150 µM CNP favorably mitigated all the LCA-based environmental indicators considered herein through declining brake specific fuel consumption, boosting brake power, as well as abating lower brake specific nitrogen oxides and brake specific carbon dioxide. The weighted environmental impacts showed that diesel/biodiesel emulsion fuels doped with 150 and 38 µM nanoadditive were the most appealing fuel blends at low and full load operations, respectively. The eco-friendliest blend was diesel/biodiesel emulsion doped with 38 µM nanoadditive with an overall score of 61.3 mPts/GJ shaft work. [ABSTRACT FROM AUTHOR]

• Effects of carbon nanoparticles on the combustion of a diesel engine were studied. • Carbon nanoparticles addition into fuels markedly lowered nitrogen oxides emissions. • Carbon nanoparticles increased unburned hydrocarbon emissions at full load conditions. • Carbon nanoparticles promoted carbon monoxide formation under full load operation. • Power generation cost could be discounted by adding carbon nanoparticles into fuels. Biodiesel utilization is associated with reduced calorific value and increased nitrogen oxides emissions. Hence, various strategies are implemented to address these challenges such as water addition into diesel/biodiesel fuel blends. In line with that, this study was undertaken to explore the effect of water (3 wt.%) and aqueous carbon nanoparticles (38, 75, and 150 µM), as a novel fuel nanoadditive, on combustion and exhaust emissions of a diesel engine at a fixed engine speed of 1000 rev/min under four different engine loads ranging from 25% to 100% of full load conditions. Overall, the engine performance characteristics were improved by incorporating the aqueous carbon nanoparticles. In particular, the incorporation of carbon nanoparticles into water-emulsified biodiesel/diesel blends generally enhanced brake power and thermal efficiency while lowering specific fuel consumption. The most appealing performance features were observed for the emulsified fuel blend containing 38 µM carbon nanoparticles which increased brake power and brake thermal efficiency by 1.07 kW and 11.58% at full load operation, respectively, while it led to decreased brake specific fuel consumption by about 107.3 g/kWh. The addition of carbon nanoparticles to the water-emulsified fuel blends adversely affected unburned hydrocarbons and carbon monoxide emissions at full load conditions owing to an increase in carbon content of the fuel blends but it lowered nitrogen oxides emissions. The addition of water deteriorated the economic features of the fuel blend (i.e., the cost per kWh of power generated). However, carbon nanoparticles addition into the water-emulsified fuel blend partially neutralized the adverse economic effects of water due to its positive impacts on thermal efficiency. Overall, water-emulsified diesel/biodiesel containing 38 µM carbon nanoparticles could be regarded as the most promising emulsion fuel in terms of engine performance characteristics, nitrogen oxides emissions, as well as fuel economy. [ABSTRACT FROM AUTHOR]

This study was aimed at performing a multi-objective fuzzy modeling and optimization of a low power, high frequency piezo-ultrasonic reactor applied for biodiesel production from waste cooking oil (WCO). To achieve this, three different fuzzy optimization methods were interfaced with adaptive neuro-fuzzy inference system (ANFIS) as modeling system to minimize the specific energy consumption of the reactor and to satisfy the ASTM standard on yield, i.e., conversion efficiency of >96.5%. Two ANFIS models were applied to correlate two output variables (conversion efficiency and specific energy consumption) individually with three input variables (reaction temperature, ultrasonic irradiation time, and methanol/oil molar ratio). The multi-objective optimization techniques included the fuzzy systems with independent, interdependent, and locally-modified interdependent objectives. Based on the results achieved, both ANFIS models excellently tracked the output parameters. Furthermore, the fuzzy system with locally-modified interdependent objectives outperformed the other two fuzzy systems in optimizing the transesterification process of WCO. The optimal WCO transesterification process for biodiesel production in the developed reactor corresponded to the methanol/oil molar ratio of 6.1:1, ultrasonic irradiation time of 10 min, and reaction temperature of 59.5 °C, leading to a conversion efficiency of 96.63% and a specific energy consumption of 373.87 kJ/kg. [ABSTRACT FROM AUTHOR]

In this study, a novel method based on Extreme Learning Machine with wavelet transform algorithm (ELM-WT) was designed and adapted to estimate the exergetic performance of a DI diesel engine. The exergetic information was obtained by calculating mass, energy, and exergy balance equations for the experimental trials conducted at various engine speeds and loads as well as different biodiesel and expanded polystyrene contents. Furthermore, estimation capability of the ELM-WT model was compared with that of the ELM, GP (genetic programming) and ANN (artificial neural network) models. The experimental results showed that an improvement in the exergetic performance modelling of the DI diesel engine could be achieved by the ELM-WT approach in comparison with the ELM, GP, and ANN methods. Furthermore, the results showed that the applied algorithm could learn thousands of times faster than the conventional popular learning algorithms. Obviously, the developed ELM-WT model could be used with a high degree of confidence for further work on formulating novel model predictive strategy for investigating exergetic performance of DI diesel engines running on various renewable and non-renewable fuels. [ABSTRACT FROM AUTHOR]

As an industrial energy plant, the whole parts of the sunflower crop were used for biofuel production through a biorefinery approach. Two scenarios were suggested for this biorefinery, i.e., using all parts of the crop separately and the whole residues as a mixture. The oil extracted from seeds was applied for biodiesel production through transesterification using a 6:1 methanol to oil molar ratio with 0.7% catalyst at 50 °C for 65 min. The process resulted in a 96.2% biodiesel yield with a heating value of 41.6 MJ/kg, corresponding to 84 kg biodiesel per ton of sunflower crop and 108.8 L gasoline-equivalent. Three physiochemical pretreatments were employed for structural modification of lignocellulosic residues, and the solid and liquid phases of the pretreatments were anaerobically digested for biomethane production. The effects of hot water (180 °C, 1 h), concentrated phosphoric acid (50 °C, 1 h, 85%), and sodium carbonate (142 °C, 18 min, 4%) pretreatments on composition, crystallinity, morphology, and biogas production of solid samples were evaluated. The highest methane yield of solid fractions was obtained from samples treated with phosphoric acid, and the seed cake showed the maximum yield of 342.7 N mL/g VS among all parts. Furthermore, the liquid phase of the hot water and alkaline pretreatments produced a high amount of biomethane, contrary to the acidic pretreatment. The overall mass balance showed that 11095.0 MJ/t energy (containing 346.7 L gasoline energy) was produced through the optimum biorefinery, where the untreated mixture and seed cake were used for biomethane production and the extracted oil for biodiesel production. [Display omitted] • Whole parts of the sunflower crop have the potential for multi-biofuel production. • The yield of biodiesel production was as high as 96.2%, with acceptable properties. • Leaves, hulls, and seed cake did not need any pretreatment for methane production. • Pretreated by H 3 PO 4 and Na 2 CO 3 were more effective on stem and capitulum. • The optimum biorefinery produced 210.9 m3 methane and 0.084 t biodiesel/ton crop. [ABSTRACT FROM AUTHOR]

Abstract: When making biodiesel, slow separation of glycerol; the main by-product of the transesterification reaction, could lead to longer operating times, bigger equipment and larger amount of steel and consequently increased production cost. Therefore, acceleration of glycerol/biodiesel decantation could play an important role in the overall biodiesel refinery process. In this work, NaCl-assisted gravitational settling was considered as an economizing strategy. The results obtained indicated that the addition of conventional NaCl salt decreased the glycerol settling time significantly up to more than five times. However, NaCl inclusion rates of more than 3g to the mixture (i.e. 5 and 10g) resulted in significantly less methyl ester purity due to the occurrence of miniemulsion phenomenon. Overall, addition of 1g NaCl/100ml glycerol–biodiesel mixture was found as optimal by accelerating the decantation process by 100% while maintaining the methyl ester purity as high as the control (0g NaCl). [Copyright &y& Elsevier]

Abstract: Energy recovery has been found to be a promising approach for disposal of polymer waste such as expanded polystyrene (EPS) which entraps large volume of air. Biodiesel known as an advantageous alternative fuel possesses bio-solvent attributes and is feasible to be used for energy recovery from EPS. In this study, maximum EPS dissolution value in biodiesel was calculated and a homogenous fuel composition was achieved. At the second phase, several biodiesel-diesel blends (B5) containing various percentages of EPS were tested in a DI diesel engine. Statistical analyses showed that addition of a limited amount of EPS led to a significant emission reduction, NOx in particular, while engine performance criteria remained stable. It was found that B5 blend containing 50 g EPS/L biodiesel was found highly advantageous on both level of performance and emissions. Despite a 3.6% reduction in brake power, a significant decrease in brake specific fuel consumption (8.5%) and increase in brake thermal efficiency (9.8%) were observed at maximum rated power and speed operation condition of the engine when the new fuel was injected. Furthermore, sustainable reductions of CO, CO2, NOx, and soot as the major exhaust emissions were achieved. [Copyright &y& Elsevier]

• Ethylene glycol diacetate was introduced as a new oxygenated diesel additive. • Diesel containing 3 vol% additive markedly mitigated nitrogen oxides formation. • The selected fuel blends could significantly mitigate carbon dioxide emission. • Brake thermal efficiency was trivially lower for the most appealing fuel blend. This study was devoted to introducing and experimenting a new waste-derived oxygenated additive, i.e., ethylene glycol diacetate on performance and emission characteristics of a diesel engine fueled with diesel/biodiesel blends. Mineral diesel and its blends with 5 and 20 vol% biodiesel were used in the engine test runs. These fuel blends were doped with ethylene glycol diacetate at three volumetric levels in the range of 1–3%. The engine was run under engine load conditions varying from idle to full load operation at a constant engine speed of 1500 rpm. Overall, the most appealing results were obtained when diesel fuel dosed with 3 vol% ethylene glycol diacetate was combusted under moderate engine load conditions. This oxygenated fuel blend could result in a significant mitigation in both nitrogen oxides and carbon dioxide emissions but could lead to an unfavorable increase in unburned hydrocarbon emissions in comparison with the additive-free diesel fuel. More specifically, nitrogen oxides and carbon dioxide emissions were reduced by 1.9–4.3 and 1.6–3.1 times, respectively, while unburned hydrocarbon emissions for the selected fuel blend under moderate engine loads were increased by 1.9–3.6 times. The carbon monoxide emission for this fuel blend was comparable with that of neat diesel. Furthermore, the significant reductions in nitrogen oxides and carbon dioxide emissions were achieved with a trivial drop in brake thermal efficiency of the engine (≈5%). As a conclusion, the developed oxygenated additive could be used for reformulating diesel fuel with the aim of substantially mitigating nitrogen oxides emissions. [ABSTRACT FROM AUTHOR]

Abstract In this study, a diesel engine was modified to operate in dual fuel mode with natural gas as the main fuel and a novel fuel mixture of biodiesel and glycerol triacetate additive as pilot fuel. Regarding to experimental tests results, engine emissions were modeled using a combination of artificial neural network and genetic algorithm to determine the appropriate ratio of pilot fuel to gaseous fuel, biodiesel and additive to reduce engine emissions. The algorithm inputs were engine torque, pilot fuel and natural gas consumption, biodiesel and additive proportions in pilot fuel, while outputs were exhaust emissions including NO x , PM, CO, and UHC. Overall, the results of the modeling were consistent well with experimental data. Simulations were performed for a variety of biodiesel and additive compositions and it was accordingly concluded that by using biodiesel and additive, NO x and CO emissions were reduced by up to 63% and 42%, respectively, while PM was reduced substantially by 27 times in comparison with neat diesel fuel in the diesel operation mode. In the dual fuel mode, 24% reduction in NOx emission. However, under these circumstances, UHC emission was 10% higher than that of the diesel operation mode. Highlights • Biodiesel and GTA additive use as pilot fuel in dual fueled engine. • GTA additive and biodiesel influence on engine emissions reduction. • Dual fueled diesel engine emissions discussed experimentally and theoretically. • Engine emissions modeled by Artificial Neural Network and Genetic Algorithm. • Engine emissions map obtained from modeling. [ABSTRACT FROM AUTHOR]

Climate change awareness has encouraged further research towards non-fossil production and consumption. Among non-fossils, biodiesel is one of the attractive alternatives to petroleum diesel. Despite the favorable properties of biodiesel, it is still faced with serious challenges regarding feedstock and catalyst used. In line with that, using waste-oriented oils and catalysts is a promising approach to ensure sustainable biodiesel production. Nevertheless, the environmental sustainability of such platforms must be carefully assessed before commercialization. The current study assesses the environmental sustainability of biodiesel production using palm kernel shell-derived sulfonated magnetic biochar through the life cycle assessment approach. Based on the results, biodiesel synthesis from waste cooking oil by palm kernel shell-derived sulfonated magnetic biochar causes 5.86E-04 DALY, 1.29E-06 species.yr, and 9.52E+01 USD2013 per tonne of biodiesel damage to human health, ecosystems, and resources categories. Transesterification and purification steps are responsible for approximately 76%, 76%, and 90% of these damages, respectively. Based on the weighted results, the total environmental impact of waste cooking oil biodiesel produced by palm kernel shell-derived sulfonated magnetic biochar stands at 1.08E+01 Pt per tonne of biodiesel, with the damage to human health category being more pronounced than the other damage categories. Generally, substituting palm oil biodiesel and diesel with waste cooking oil biodiesel produced by the developed catalyst could lead to an 89% and 55% decrease in total weighted impacts. Overall, the catalyst developed in this study could be a favorable alternative to homogeneous catalysts used in biodiesel production, causing much discounted environmental burdens. [Display omitted] • Biodiesel production catalyzed by palm kernel biochar is environmentally analyzed. • Transesterification of waste cooking oil accounts for 79% of biodiesel's carbon emissions. • The transesterification of waste cooking oil causes about 90% of resource damage. • Biodiesel shows a significant 55% reduction in total weighted impacts over traditional diesel. • Substituting palm oil with waste oil reduces 89% of the total environmental impacts. [ABSTRACT FROM AUTHOR]

Renewable energy generation through biorefineries is increasingly considered as more sustainable in comparison with fossil-based fuels as well as single-product renewable energy systems. However, biorefineries have many system variations, and therefore, the evaluation of their environmental performance and comparison with conventional systems before large-scale deployment is essential. In this paper, the sustainability of three different biorefiney scenarios (Sc-1, Sc-2, and Sc-3) based on Eruca sativa ( ES ) as feedstock were investigated using a life cycle assessment approach from energy balance and environmental point of views. Biodiesel, electricity, ethanol, heat, glycerol, and/or biomethane were the marketable products taken into account under the conditions of these scenarios. According to the results obtained, we argue that although biorefineries offer unique features as most effective alternatives for mitigating climate change and reducing dependence on fossil fuels, the selection of biomass processing options and management decisions can widely affect the final evaluation results. Overall, providing transportation fuel through Sc-2 in which biodiesel, electricity, ethanol, heat, and glycerol were produced could decrease GHG emissions by approximately 140% compared with the combustion of neat diesel while also offering a total net energy gain (NEG) of 4.94E+08 MJ/yr. Nevertheless, if biorefineries are to be used for future transportation fuel production, a great deal of efforts should still be made to achieve better environmental performance in the Human Health and Ecosystem quality damage categories. [ABSTRACT FROM AUTHOR]

Diesel fuel exhibits high efficiency, durability, and profitability for combustion engines but remains a major source of airborne pollutants, including particulate matter and nitrogen oxides. To address the urgent need for alternative energy sources and reduce greenhouse gas emissions, biodiesel has been developed as a potential replacement for petrodiesel. However, biodiesel combustion has its drawbacks, especially the emission of nitrogen oxides, which hinder its ability to replace petrodiesel sustainably. Nanotechnology has been proposed as a promising solution to improve biodiesel combustion and enhance its competitiveness against petrodiesel. Various studies have shown that both metallic and non-metallic nanoparticles can potentially enhance biodiesel performance during combustion, improving fuel combustion efficiency by 11.7% and 13.4% while reducing air pollutants such as carbon monoxide by 24.2% and 24.8% and unburned hydrocarbons by 11.5% and 25.3%, respectively. While both types of nanoparticles can potentially reduce greenhouse gas and particulate matter emissions, their impact on nitrogen oxide emissions varies. Non-metallic nanoparticles are more successful in reducing nitrogen oxide emissions, achieving reductions of up to 13.0%, while metallic nanoparticles have been shown to increase nitrogen oxides by 0.8% on average. In the post-combustion phase, nanoparticles can filter pollution from diesel engines with more than 99% efficiency, reducing friction, enhancing engine durability, preventing deposit formation, and reducing maintenance costs. However, using nanoparticles in biodiesel has several drawbacks, including toxicity to humans and ecosystems, high prices, lack of standardization, and limited understanding of their long-term effects. Further research is needed to address these constraints and ensure the safe and effective use of nanoparticles in biodiesel combustion. The potential benefits of nanotechnology for improving biodiesel combustion and reducing emissions can make this research field an exciting avenue for future research and development. [Display omitted] • Nanoparticles improve biodiesel combustion/engine efficiency while mitigating emissions. • Metallic and non-metallic nanoparticles have different effects on nitrogen oxide emissions. • Post-combustion nanoparticles can filter exhaust emissions with over 99% efficiency. • Nanoparticles can reduce friction, enhance engine durability, and lower maintenance costs. • Further research is needed to address nanoparticle toxicity, pricing, and standardization. [ABSTRACT FROM AUTHOR]

Improving fuel combustion in engines and consequently reducing environmentally-unfavorable emissions is of prominent importance in addressing some of the main challenges of the current century, i.e., global warming and climate change. Fuel additives are considered as efficient way for improving fuel properties and to diminish engine emissions. In line with this, the present research was focused on the simultaneous application of water (3, 5, and 7 wt.%) and cerium oxide nano particles (90 ppm) as metal-based additive into biodiesel/diesel fuel blend (B5) and their impacts on the performance and emission characteristics of a single cylinder four stroke diesel engine were investigated. The findings revealed that the aqueous nano-emulsion of cerium oxide improved the overall combustion quality. More specifically, the brake specific fuel consumption (bsfc) of B5 containing 3% water and 90 ppm cerium oxide (B5W3 m ) was measured 5% and 16% lower than those of neat B5 and neat B5 containing 3% water (B5W3), respectively. Moreover, the B5W3 m fuel blend increased brake thermal efficiency (bte) by over 23 and 11% compared with B5W3 and B5, respectively. B5W3 m also considerably reduced CO, HC, and NO x emissions by 51, 45, and 27% compared with B5W3. To the best of our knowledge, this is the first report exploring the impacts of low-level water containing cerium oxide in B5 on engine performance and emission characteristics. [ABSTRACT FROM AUTHOR]

Diminishing fuel resources and stringent emission mandates have demanded cleaner combustion and increased fuel efficiency. Three water addition rates, i.e., 2, 4, and 6 wt% in biodiesel-diesel blend (B5) was investigated herein. Combustion characteristics of the emulsified fuel blends were compared in a naturally-aspirated diesel engine at full load and different engine speeds. More specifically, biodiesel was produced from waste cooking oil (WCO) and to further increase waste utilization, recycled biodiesel wastewater was used as additive in B5. The result obtained showed that low-level water addition (i.e., 2 and 4 wt%) in B5 led to different results from those obtained using higher water addition rates (i.e., >5 wt%) reported by the previous studies. In more details, the findings of the present study revealed that low level water addition in B5 could considerably reduce CO, HC, CO 2 , and NO x emissions. Among water-containing B5 fuel emulsions, the optimal water addition level in terms of engine performance parameters and emissions was found at 4 wt%. In particular, the emitted CO 2 , HC, and NO x were decreased by over 8.5%, 28%, and 24%, respectively, at maximum speed of 2500 rpm. [ABSTRACT FROM AUTHOR]

A large volume of oil palm empty fruit bunch (EFB) is generated as waste feedstock around the globe. This abundant waste containing 0.75% oil on average could be a promising feedstock for biodiesel production if oil recovery could be accomplished in an economically-viable and environmentally-friendly manner. To achieve that, a new method called High Pressure Water Spray (HPWS) system was introduced and performed by spraying pressurized water (500 psi) at 30 °C, 60 °C, and 90 °C and combination of water-steam at 120 °C and 150 °C onto the surface of the oil palm empty fruit bunches (EFB). The results obtained indicated that, the highest oil removal yield of 94.41 ± 0.02 wt% was obtained at 150 °C. Moreover, bioprospection of biodiesel properties based on fatty acid methyl ester (FAME) profile revealed that the biodiesels produced from the fresh crude palm oil and residual oil were comparable and were in accordance with international standards. In addition to that, the HPWS process led to an enhanced quality of the remaining lignocellulosic materials for conversion into other value added bio-products such as ligno-ethanol by decreasing lignin content and increasing cellulose content. In view of environmental impact assessment, the HPWS system showed favorable impacts on all the end-point damage categories especially in resources damage category. Moreover, economic assessment showed that the recovered CPO could be generated at a low price of USD 0.41 vs. USD 0.66 for CPO. Overall, this process could drastically increase the market value of an abundant type of waste in many parts of the world, i.e., EFB leading to the generation of additional wealth for the palm oil industry. [ABSTRACT FROM AUTHOR]

Biodiesel was produced herein from the oil contained in waste spent bleaching earth (SBE), an environmental pollutant generated through the refining processes of edible oils in oil extraction plants. To further increase waste utilization, waste expanded polystyrene (EPS) was also dissolved in SBE biodiesel (0, 2.5, 5, and 7.5 g/100 ml). Performance parameters and emission characteristics of 5% blend of EPS-SBE biodiesel and diesel were then investigated in a naturally aspirated diesel engine. The results obtained demonstrated that polymer-free SBE-B5 at 1600 rpm and full load led to enhanced brake power and brake mean effective pressure by approximately 1.5%. Moreover, the emitted HC, CO, and smoke were decreased by over 40%, 80%, and 20%, respectively, with polymer inclusion at 2.5 g/100 ml in SBE-B5 at maximum speed of 2600 rpm and full load (280 N m). While the optimal polymer inclusion level of 2.5 g/100 ml had subtle impacts on engine performance parameters. The findings of the present study could be of great interest to waste valorization industries since an integrated strategy was offered to simultaneously handle two environmental pollutants (SBE oil and EPS wastes) while a more environmentally-friendly fuel blend (i.e., SBE-B5 containing 2.5 g EPS/100 ml) was also achieved. [ABSTRACT FROM AUTHOR]

The boom of the biodiesel industry has ramped up global glycerol production. Unfortunately, a large portion of the glycerol generated by this growing industry is recklessly discharged into the environment, overshadowing the environmental benefits of biodiesel fuel. Glycerol can be a valuable chemical platform in various processes to produce a wide spectrum of chemicals and fuels. A promising application pathway is to return glycerol to the fuel cycle by converting it into fuels or additives. The energy content of glycerol can then be effectively recovered while the harmful exhaust emissions of combustion engines can be substantially mitigated. This paper offers a broader review of the state-of-the-art advances in using glycerol and its derivatives to improve the operation of internal combustion (IC) engines. Various routes developed to convert glycerol into oxygenated fuel additives are first introduced. The effects of glycerol and its derivatives on the behavior of IC engines are then comprehensively summarized and mechanistically discussed. The pros and cons of using glycerol and its derivatives in diesel/gasoline fuel formulations are examined to highlight important future research directions in this domain. Overall, the straight or emulsified use of glycerol in IC engines is not recommended because of several challenging technical and environmental issues. Nevertheless, incorporating well-elaborated glycerol derivatives into diesel and gasoline fuels can improve engine performance while potentially lowering hazardous exhaust emissions. Future investigations should focus on manufacturing and examining new glycerol derivatives to enhance the performance of IC engines while meeting stringent emission norms. [Display omitted] • The use of glycerol and its derivatives in internal combustion engines is reviewed. • Biodiesel glycerol conversion into oxygenated fuel additives is briefly explained. • The direct and emulsified use of glycerol in internal combustion engines is unfavorable. • Glycerol-based additives can improve the performance of diesel and gasoline engines. • Oxygenated additives can lower the hazardous emissions of internal combustion engines. [ABSTRACT FROM AUTHOR]

Climate change is a worldwide concern due to unfavorable consequences on human health and ecosystem quality. Accordingly, the world is looking for strategies to stop this destructive phenomenon. Biodiesel production is one of the promising strategies to decrease diesel consumption as one of the most important contributors to climate change. The carbon contained in biodiesel is derived from biogenic carbon dioxide, and therefore, it has a lower contribution to the atmospheric carbon pool and global warming. However, biodiesel suffers from poor stability due to the radical-mediated oxidative degradation of the fuel. The susceptibility of biodiesel towards oxidative degradation, attributed to the presence of points of unsaturation in the form of mono and polyunsaturated fatty acids, can be addressed by antioxidants. However, the presence of antioxidants in biodiesel might also change fuel behavior in diesel engines. Accordingly, the present study reviews and critically discusses biodiesel stability in the presence of antioxidants and, subsequently, the behavior of biodiesel doped with antioxidants in diesel engines. This review shows that antioxidants are highly effective in quenching the free radicals involved in oxidative chain reactions. Biodiesel treatment with synthetic antioxidants is a promising approach to increase biodiesel stability, but they may be toxic to humans and other organisms. Antioxidants extracted from plants and agri-food residues can help overcome this challenge and even lead to sustainable antioxidants production within circular bioeconomy frameworks. In addition to the stability problem, biodiesel suffers from higher nitrogen oxides emissions vs diesel. Antioxidants are also an effective solution to mitigate this emission by quenching free radicals. However, the quenching of radicals is accompanied by a setback in the oxidation process in the combustion engine, leading to higher smoke, unburned hydrocarbons, and carbon monoxide. Due to the impacts of these gases on human health, future studies should move towards the introduction of antioxidant compounds whose negative aspects are discounted. [Display omitted] • The effects of antioxidants on biodiesel stability are comprehensively discussed. • Engine behavior in response to antioxidant-doped biodiesels is critically reviewed. • Antioxidants through quenching free radicals can decrease nitrogen oxides. • Antioxidant-doped biodiesel increases carbon monoxide and hydrocarbons emissions. [ABSTRACT FROM AUTHOR]

When making biodiesel, slow separation of glycerol; the main by-product of the transesterification reaction, could lead to longer operating times, bigger equipment and larger amount of steel and consequently increased production cost. Therefore, acceleration of glycerol/biodiesel decantation could play a significant role in economic viability of the overall biodiesel refinery process. In the present study, the interactive effects of prominent parameters i.e. temperature (25-65 °C), NaCl addition (0-2 g/100 ml), and methanol concentrations (10-30 vol.%) on decantation behavior of glycerol/biodiesel mixture were studied using Box-Behnken design matrix and response surface methodology (RSM). The findings revealed that in low temperature ranges, the main factor influencing decantation speed was density difference while at high temperature ranges, viscosity variation played the major role. Moreover, decantation time was significantly decreased by 200% (3 min) at the optimum conditions achieved i.e. 45 °C, 1 g NaCl addition and 20% excess methanol. The methyl ester yield was measured at >90% under optimum conditions which was increased to ASTM quality (>96.5%) after washing and drying procedures. [ABSTRACT FROM AUTHOR]

• Emission and performance parameters of a dual-fuel diesel engine were studied. • The engine operated with high natural gas substitution rates under various loads. • The pilot fuel was diesel/biodiesel emulsions doped with carbon nanoparticles. • The developed fuel blends could ignite well natural gas at high substitution rates. • Pilot fuel composition markedly affected engine emissions and performance. The dual-fuel (DF) combustion process is a promising engineering solution to achieve clean combustion and high thermodynamic efficiency. The composition of pilot fuel (PF) can be considered as one of the effective parameters on the combustion quality of the DF process. In general, employing biodiesel blended fuel samples as PF can reduce brake power (BP) and increase fuel consumption. Therefore, developing fuel formulations harboring additives that are capable of boosting brake power (BP) and reducing fuel consumption of DF diesel engines (DFDEs) while also mitigating their harmful emissions, is highly considered. To this end, the present study was set to investigate emission and performance characteristics of a natural gas (NG) DFDE ignited by water-emulsified (WE) diesel/biodiesel (D/B) blends (5 vol% biodiesel and 3 wt% water) containing 30 and 60 µM aqueous carbon nanoparticle (CNP). Neat diesel and D/B blend containing 5 vol% biodiesel were used as control fuel. The engine was fueled with high NG substitution rates (50–80% of the total fuel energy) at engine loads (25–100% of full load). Overall, emissions and performance characteristics of the engine were significantly affected by engine load and NG substitution rate. On average, the WE D/B blend doped with 30 µM could provide acceptable results in terms of engine emissions and performance. This fuel formulation could mitigate unburned hydrocarbon emissions by about 8 to 40% at different loads, even though increased NOx emissions. The power generation cost of the selected fuel blend was also about 5 to 23% lower than the control fuels. [ABSTRACT FROM AUTHOR]

The huge amount of agro-wastes generated due to expanding agricultural activities can potentially cause serious environmental and human health problems. Using the biorefinery concept, all parts of agricultural plants can be converted into multiple value-added bioproducts while reducing waste generation. This approach can be viewed as an effective strategy in developing and realizing a circular bioeconomy by accomplishing the dual goals of waste mitigation and energy recovery. However, the sustainability issue of biorefineries should still be thoroughly scrutinized using comprehensive resource accounting methods such as exergy-based approaches. In light of that, this study aims to conduct a detailed exergy analysis of whole-crop safflower biorefinery consisting of six units, i.e., straw handling, biomass pretreatment, bioethanol production, wastewater treatment, oil extraction, and biodiesel production. The analysis is carried out to find the major exergy sink in the developed biorefinery and discover the bottlenecks for further performance improvements. Overall, the wastewater treatment unit exhibits to be the major exergy sink, amounting to over 70% of the total thermodynamic irreversibility of the process. The biomass pretreatment and bioethanol production units account for 12.4 and 10.3% of the total thermodynamic inefficiencies of the process, respectively. The exergy rates associated with bioethanol, biodiesel, lignin, biogas, liquid digestate, seed cake, sodium sulfate, and glycerol are determined to be 5918.5, 16516.8, 10778.9, 1741.4, 6271.5, 15755.8, 3.4, and 823.5 kW, respectively. The overall exergetic efficiency of the system stands at 72.7%, demonstrating the adequacy of the developed biorefinery from the thermodynamic perspective. • Waste quantity can be largely minimized in agriculture using the biorefinery concept. • Safflower biorefinery co-producing various bioproducts is exergetically analyzed. • Over 70% of the total irreversibility of the plant occurs in the wastewater treatment unit. • Biodiesel exhibits the highest exergy rate among the plant products/by-products. • The overall exergetic efficiency of the developed process stands at 72.7%.. [ABSTRACT FROM AUTHOR]

Abstract: The cost of biodiesel production can be reduced by a number of strategies such as utilization of waste cooking oils and non-edible plant oils as well as implementation of improved separation technologies. In addition, processes dealing with the glycerol by-product can have economic benefits. In the present study, acidification of crude glycerol with phosphoric acid to pH 9.67 followed by acidification to 4.67 was implemented to produce high quality potassium phosphate during glycerol purification. KH2PO4, K2HPO4, glycerol and free fatty acids (FFAs) with a purity of 98%, 98.05%, 96.08% and 99.58% were obtained, respectively. [Copyright &y& Elsevier]

Biodiesel has a lower oxidation stability index (OSI) than mineral diesel fuel. Its consequential oxidation products and deteriorated physical and chemical properties of fuel are associated with engine operation challenges such as the formation of insoluble gums that can plug fuel filters. Given the fact that oxidation leads to barriers for commercial use of biodiesel, addition of appropriate antioxidants into biodiesel is a promising and cost-effective approach to overcome this challenge. Although synthetic antioxidants such as propyl gallate (PG) are frequently used to counter the oxidation process of biodiesel, PG is a designated carcinogen. In light of that, this study was conducted aiming at introducing walnut husk methanolic extract (WHME) as a more sustainable antioxidant to replace PG in waste cooking oil (WCO) methyl esters. Moreover, to facilitate the commercialization of the new product, a comprehensive environmental investigation and comparison with the conventional counterpart, i.e., PG, was performed using life cycle assessment (LCA) approach. To enhance the eco-friendly features of the natural antioxidant, a solar photovoltaic-driven extraction process based on methanol (as reagent) was used in extracting polyphenols from walnut husk. The results showed that the induction period of WCO methyl esters was prolonged from 1.2 h to more than 3 h (meeting the ASTM D6751 standards) using 5000 ppm and 250 ppm of WHME and PG, respectively. More specifically, 20-fold more natural antioxidants would be required to meet the international standards. However, since walnut-producing countries are responsible for 42.4% of global biodiesel production on one hand and the cost-effectiveness of walnut husks on the other hand, their valorization could attract the attention of the global biodiesel industry. Moreover, this study highlights the considerable environmental and health benefits of turning this bio-waste product into a value-added antioxidant fuel additive. The LCA results showed that the developed bio-antioxidant was more effective in different damage categories compared with PG, i.e., 0.32% in ecosystem quality, 12.13% in human health, 8.37% in climate change, and 614% in resource. Overall, the WHME obtained through solar photovoltaic-driven extraction process could outcompete PG from the environmental perspective. Image 1 • Solar photovoltaic-driven walnut husk extract was used as biodiesel antioxidant. • The health aspects of waste-oriented biodiesel were improved. • A potentially carcinogenic antioxidant was replaced with an agro-waste counterpart. • Antioxidant capacity of natural antioxidant was comparable with that of propyl gallate. • LCA results found the bio-antioxidant are more advantageous in all impact categories. [ABSTRACT FROM AUTHOR]

• A safflower-based biorefinery co-producing bioethanol and biodiesel was developed. • Ethanol production by Z. mobilis and S. cerevisiae was techno-economically compared. • Ethanol production using Z. mobilis was economically-justified for implementation. • Z. mobilis lowered both ethanol production cost and minimum ethanol selling price. Safflower plant is a promising energy crop, which is compatible with arid and semi-arid climate conditions. This study is set to perform a techno-economic assessment of an integrated biorefinery located in Iran, using safflower seed and safflower straw as feedstock for production of bioethanol as the main product, biodiesel as the most valuable byproduct while biogas, glycerol, solid residue, and sodium sulfate are the other valuable byproducts. In the first Scenario (A), glucose, xylose, and arabinose are fermented into ethanol by using Zymomonas mobilis produced in a seed train unit. While in the other Scenario (B), Saccharomyces cerevisiae is supplied externally by a yeast production facility and is used to ferment glucose into ethanol. Both scenarios are simulated using Aspen Plus software and a cash flow analysis is performed using well-known economic indices for the biofuel industry presented by the National Renewable Energy Laboratory. The profitability index is 1.14 for Scenario A, showing its cost-effectiveness. However, this index is found to be 0.81 for Scenario B, revealing the fact that this approach is not economically-justified for implementation. More specifically, the use of Z. mobilis instead of S. cerevisiae as fermenting microorganism enhances the profitability of the project by lowering ethanol production cost from 0.12 $/L to 0.09 $/L and minimum ethanol selling price from 0.67 $/L to 0.43 $/L. Moreover, in both scenarios, biodiesel production boosts the total annual sale values by 39% and 55% for scenario A and B, respectively. In general, 1.86 and 2.44 times improvements in this economic index are respectively obtained for scenario A and B because of byproduct credits. The outcomes of sensitivity analysis also shows that the discount factor and safflower seed price have large impacts on the profitability of the developed biorefineries. Overall, Z. mobilis appears to be a preferred biocatalyst for bioethanol fermentation through the biorefinery platform from the techno-economic viewpoint. [ABSTRACT FROM AUTHOR]