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Abstract This paper reviews various aspects of the enzymatic transesterification method to convert used cooking oil to biodiesel. The goal of this paper is to provide a thorough overview from general biodiesel production processes, reaction conditions, challenges, and solutions for higher biodiesel production yield through introducing various microorganisms that are capable of producing the enzymes required to convert used cooking oil into biodiesel. The characteristics, composition, and advantages of the used cooking oil, as feedstock for biodiesel, is also discussed. In addition, the existing transesterification methods including homogeneous alkali-catalyzed, homogeneous acid-catalyzed, non-catalytic reaction under super-critical conditions, and enzyme-catalyzed reactions are explained. Furthermore, the advantages of the enzymatic method over other methods, and the enzymes, which are the key elements of such reactions, are discussed. Lipases are the most promising enzymes currently known for biodiesel conversion. The physiological and physical properties of microbial lipases, the catalytic mechanisms of the enzymes, various methods of enzyme immobilization such as adsorption, covalent and affinity binding, entrapment, and the whole-cell immobilization are also reviewed. At the end, three case studies demonstrating unique and efficient enzymatic transesterification approaches are presented. Highlights • General biodiesel production and existing transesterification processes. • The benefits and issues of using waste cooking oil as feedstock. • Various sources of microorganisms to produce enzymes, and catalytic mechanisms. • Adsorption, covalent binding, affinity, entrapment and whole-cell immobilization. • Case-studies demonstrating unique techniques of biodiesel production using enzymes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ultrasound multifrequency system can measure SoS and Att of pure oils and biofuels blends. • Equivalence for SoS and Att in vegetable oils with similar composition was disclosed. • Low concentration of contamination that can be assed with ultrasound technique. • The method accuracy and robustness were metrologically assessed. Abstract Whilst fossil fuels have been an industrial driver for many decades, environmental concerns related to global warming have driven the development of alternative energy sources, such as the generation of biodiesel from vegetable oils. For a biodiesel to be commercialised, it must meets property and quality requirements from International Standards. Most of these checks must be performed off-line, with significant costs in terms of shutdown time and testing. On the other hand, ultrasound measurement can provide an in-line monitoring tool to assess the advance of transesterification. Although this was highlighted in previous works, hitherto this has not been the subject of a detailed metrological approach to define the uncertainty associated with ultrasound techniques applied to biodiesel and related liquids. This paper presents such research and addresses measurement of two ultrasound parameters, Speed of Sound (SoS) and attenuation coefficient (Att), and their capability of assessing macroscopic characteristics of the biodiesel. The liquids tested were pure edible oils (vegetable, corn, and sunflower), castor oil, pure biodiesel (B100), as well as blends of biodiesel with common contaminants or by-products related to biodiesel transesterification. Details of the biodiesel manufactured were varied, using different stirring speeds of rotation (200 rpm and 550 rpm), temperatures (40 °C and 50 °C), and KOH catalyst concentrations (0.2% and 1.5%). Contaminants added to pure biodiesel were methanol (0.10% and 0.20%), glycerol (0.10% and 0.15%) and triglyceride (2%). The acoustic characteristics of these liquids were determined relative to water using a broadband through-transmission substitution method covering the frequency range 1–20 MHz. Normalized error analysis has been applied to assess the equivalence of experimental results, as well as to discriminate the detection sensitivity of the technique. From the measurements, all edible oils showed equivalent experimental values for SoS and Att over the usable frequency band 2 MHz to 18 MHz. In contrast, biodiesel produced from sunflower and different reaction routes led to SoS and Att which were statistically different over the same frequency range, reflecting the ability of ultrasound to monitor low-level contamination of different blends. Finally, the paper concludes that ultrasound shows promise as a means of assessing biodiesel quality and purity with sensitivity sufficient to discern contaminants in a proportion as low as 0.1% in mass for Att measurements. [ABSTRACT FROM AUTHOR]

Cultivation of microalgae using wastewater has received considerable attention around the globe as a platform to remove inorganic nutrients from the wastewater and producing microalgae biomass for biodiesel production. This can be done by converting freely available nutrients from the wastewater (particularly nitrogen, N and phosphorus, P) into microalgae biomass with concomitant carbon dioxide (CO 2 ) sequestration via photosynthesis process. In fact, microalgae biodiesel could help to reduce greenhouse gas (GHG) emissions to the atmosphere through the replacement of fossil diesel as it is made from renewable resources. Despite the various benefits to produce microalgae biodiesel, a number of technical hurdles such as complex processes, requirement of high energy input during cultivation and dewatering (harvesting steps) need to be addressed for commercialization purpose. Besides, additional pre-treatment step is necessary to disrupt the microalgae cell wall to enhance lipid extraction efficiency. Hence, this paper is aims to reveal in-depth analysis and discussions on the process of microalgae-based wastewater treatment as well as microalgae cells disruption technology for lipid extraction. The paper also includes several new directions for technological improvements to improve commercialization potential of microalgae biodiesel. [ABSTRACT FROM AUTHOR]

This literature review discusses several aspects of biodiesel production from microalgae. This paper elucidates the optimal bioenvironmental conditions for microalgae cultivation, process design of algal biodiesel production, physicochemical properties of lipids extracted from microalgae and the properties of the produced biodiesel fuel, and the transesterification process. On the other hand, this paper illustrates the designs of up-to-date full-scale and lab-scale photobioreactors (PBRs). Furthermore, this paper argues different bioengineering aspects of biodiesel production from microalgae. Eventually, the measurements, calculations, design parameters, Life Cycle Analysis (LCA) of the production process are discussed. [ABSTRACT FROM AUTHOR]

Direct use of Waste Vegetable Oil (WVO) as fuel is very attractive to reduce fossil fuels utilization and increase sustainability. WVO incorrect disposal causes serious damages to sewage systems and wastewater treatment plants. Moreover, if WVO reaches natural ecosystems, such as rivers, aquifers or subsoil, the environmental consequences can be severe. In recent years, the main reuse of WVO has been in biodiesel production, which is remunerative under current tax allowance policies. However, biodiesel production requires complex physical–chemical treatments, while direct use of WVO just needs mechanical treatment. As a consequence, WVO direct use in energy conversion systems lower the impact, from the economic, energetic and environmental points of view, with respect to biodiesel production. Moreover, as concerns the environmental impact, it should be considered that the direct use of WVO as fuel produces less polluting emissions when considering the whole life cycle: carbon dioxide produced during combustion, in fact, can be partially absorbed by crops used for oil production. This paper presents a comprehensive review of the work done to evaluate the effects of direct use of WVO in internal combustion engines. Many authors have shown the advantages of using straight vegetable oils or biodiesel produced from WVO as fuel, while the benefits of WVO direct use have not yet been clearly presented. The available literature still presents few papers about this topic, therefore also the use of vegetable oil, that presents physical chemical characteristics very similar to those of WVO, has been taken into account. After a brief introduction, the characteristics of WVO most affecting its use as fuel have been studied. Then several applications of WVO direct use in internal combustion engines and the available fuel supply technologies have been considered. Finally, the energetic performance and the pollutant emissions reported in literature have been deeply analyzed. [ABSTRACT FROM AUTHOR]

Jatropha curcas L. is a growing feedstock for biodiesel production. The first step in the exploitation of any plant for industrial application is to gather information about its chemistry, biology and all different applications so that the utilization of plant could be used optimized. J. curcas has been the centre of interest for many scientists in the past decade. The purpose of this paper is to present state-of-the-art review of J. curcas research advancement in biological, agronomical and biotechnological areas. This paper gives an overview on plantation science, composition, toxicity and genetics of J. curcas . This review also focuses on all J. curcas uses in agronomical terms. It gives a general idea of agricultural potential, utilizations, medical uses and other molecules that have been extracted from the plant. It finally focuses on the energy production from the crop and the biotechnological improvement of the biodiesel production process. [ABSTRACT FROM AUTHOR]

Abstract: Recently, non-edible vegetable oils have been considered as prospective feedstocks for biodiesel production. This is mainly attributed to their ability to overcome the problems of food versus fuel crisis related to edible oils. Globally, there are more than 350 oil-bearing crops identified as potential sources for biodiesel production. The evaluation of the physical and chemical properties of non-edible feedstocks is very important to assess their viability for future biodiesel production. Therefore, this paper aims to study the properties of some potential non-edible feedstocks. Moreover, the paper studies the physical and chemical properties of these promising crops and compares them with other edible oils. These oils include: crude Calophyllum inophyllum L. (CCIO), Jatropha curcas L. (CJCO), Sterculia foetida L. (CSFO), Croton megalocarpus L. (CCMO), Moringa oleifera L. (CMOO), patchouli (CPO), coconut (CCO), palm (CPaO), canola (CCaO), soybean (CSO) and Pangim edule (CPEO) oils. 14 Different properties have been determined and presented in this study. [Copyright &y& Elsevier]

Abstract: Despite the high energy demand in the industrialized world and the pollution problems caused by widespread use of fossil fuels, the need for developing renewable energy sources with less environmental impacts are increasing. Biodiesel production is undergoing rapid and extensive technological reforms in industries and academia. The major obstacle in production and biodiesel commercialization path is production cost. Thus, in previous years numerous studies on the use of technologies and different methods to evaluate optimal conditions of biodiesel production technically and economically have been carried out. In this paper, a comparative review of the current technological methods so far used to produce biodiesel has been investigated. Four primary approaches to make biodiesel are direct use and blending of vegetable oils, micro-emulsions, thermal cracking (pyrolysis) and transesterification. Transesterification reaction, the most common method in the production of biodiesel, is emphasized in this review. The two types of transestrification process; catalytic and non-catalytic are discussed at length in the paper. Both advantages and disadvantages of the different biodiesel production methods are also discussed. [Copyright &y& Elsevier]

Abstract: Biomass is an alternative to replace the use of fossil fuels. Glycerol, a byproduct in the biodiesel production, can be used for obtaining hydrogen. The most efficient method for obtaining hydrogen from glycerol is the steam reforming (SR). So far all the published papers report the use of conventional catalyst. In this paper, a structured catalyst has been prepared and compared with the conventional ones (powder and spherical pellets). Results show that the structured catalyst (monolith) is more stable as formation of coke was not observed. [Copyright &y& Elsevier]

Abstract: The raw material supply bottleneck is one of the obstacles currently facing the development of China''s biodiesel industry. The main objective of this paper is to analyse the demands, possibilities, difficulties and suggestions surrounding the participation of restaurant enterprises in the biodiesel supply chain. Based on an analysis of the overall situation of China''s biodiesel supply chain, the authors designed a structured questionnaire to survey 246 restaurant enterprises in Nanjing. The questionnaire mainly included basic aspects of restaurant enterprises, disposal of waste cooking oil (WCO), awareness and attitudes towards WCO recycling, understanding and opinion of biodiesel, and willingness and requirements for participating in the production of biodiesel. Factor analysis was then conducted on the motives of industrial restaurant enterprises for disposing of or recycling their WCO, and cluster analysis was used to classify the 246 restaurant enterprises into three clusters. Finally, the authors suggested ways to promote the development of Nanjing''s biodiesel supply chain. The significant findings obtained in this paper will help to encourage restaurant enterprises to become suppliers of biodiesel production and promote the healthy development of the biodiesel industry in China. [Copyright &y& Elsevier]

Abstract With their fast growth rate and ability to accumulate a high percentage of their weight as lipid and carbohydrate, microalgae potentially represent an ideal feedstock for the production of biodiesel and bioethanol. In addition, microalgae offer several environmental benefits, and do not compete with food production for land, fresh water, and nutrients. Therefore, the main goal of this work is to provide a quantitative, systematic and harmonized assessment of current bio-energy potential. The analysis is conducted by considering all the main steps in detail, from cultivation to biodiesel production, and by deriving an overall estimation of energy consumption for biodiesel production. Energy consumption uncertainty is also quantified and discussed. A systematic review of all the main technologies available for all the main processing steps towards the production of biodiesel from microalgae is presented, focusing on the derivation of the Net Energy Ratio (NER) of each combination of technologies, complemented by an uncertainty analysis of the data used and those obtained in the present work. A wide scatter in the data available in the literature has been identified, highlighting the need for an uncertainty analysis. If the average overall energy consumption per unit of biodiesel mass is considered, all the routes adopting a raceway pond have a lower energy consumption, but if the uncertainty on the overall energy consumption is also considered, the minimum value of the range of NER values for some of the routes adopting a photobioreactor is comparable to the NER value obtainable by using raceway ponds. Thus, the present framework proposes a harmonized and comprehensive methodology to compare and contrast technologies for the production of biodiesel from microalgae, and is applied in this paper to identify, with an appreciation of the uncertainty, the most promising combinations of technologies. Highlights • Quantitative, systematic and harmonized assessment of microalgae energy potential. • A step-by-step analysis and overall estimation of energy consumption is given. • A substantial uncertainty on the data in literature has been identified. • The energy consumption uncertainty is quantified and critically discussed. • Derivation of the Net Energy Ratio (NER) for each combination of technologies. [ABSTRACT FROM AUTHOR]

Biodiesel from non-grain feedstock has been considered as one of the proper substitutes for fossil fuels associated with a series of activities emerging in China in order to meet the resource shortage and develop the energy crops. This paper presents an ecological accounting framework based on embodied energy, emergy, and CO2 emission for the whole production chain of biodiesel made from Jatropha curcas L. (JCL) oil. The energy and materials invested in and CO2 emission from the whole process, including cropping, transportation, extraction, and production, are accounted and calculated. Also, EmCO2, the ratio of real CO2 released to the emergy-based sustainability indicator per joule biodiesel, is proposed in this paper to present a new goal function for low-carbon system optimization. Finally, the results are compared with those of the bioethanol (wheat) production in Henan Province, China, and bioethanol (corn) production in Italy in view of the indices of embodied energy, emergy and CO2 emissions and EmCO2. [Copyright &y& Elsevier]

Abstract: This paper presents the outcomes of a questionnaire survey to ascertain the perspectives of local communities on the proposal to construct a large-scale biodiesel production facility in the Eastern Cape Province of South Africa, with feedstock supply to the production facility from the former communal homelands of the Province. A total of 303 questionnaires were administered through interactions with the communities that are expected to be a part of the feedstock production supply chain by visiting households and having in-depth interviews, and through a focus group discussion. Opinions were found to be overwhelmingly against the proposed biodiesel production supply chain. The concerns of local people varied, but the major issues were land availability as this is regarded as their identity; infrastructure development; associated pollution (air and water) posing serious health risk; doubts about the credibility of the developers; food security; and the distortion of the social fabric of the local communities. In general, local people felt that they were excluded from the project development and were asked to accept industrial scale development that will further lead to the impoverishment of the communities. The results also highlighted how large-scale plants may be affected by the local dynamics of perceptions; the willingness to partake in the supply chain was informed by personal, social and institutional factors and beliefs, as well as internal conflicts, due to perceived environmental, social and ecological risks, that were aggravated by miscommunication and the lack of understanding. The paper is deemed useful for policy makers to understand why communities may object to relatively large bioenergy projects, and to assist the developers of such projects to avoid delays and refusal of planning consent that can be associated with adverse local opinions. [Copyright &y& Elsevier]

Abstract: Among the options explored for alternative energy sources, bio-diesel is one of the attractive alternatives. This paper discusses about the various production processes, few of which are applied at industrial level, to produce basically FAME (later can be utilized as bio-diesel after purification) and will be termed as bio-diesel in this paper. Transesterification of vegetable oils/animal fats and extraction from algae are the leading processes for bio-diesel production on large scale. This paper reviews briefly the literature on transesterification reaction using homogeneous, heterogeneous and enzyme catalysts. It is also reviewed the ultrasound, microwave and supercritical alcohol techniques and algae based bio-diesel. [Copyright &y& Elsevier]

Abstract: This paper presents production of biodiesel (BD) from non-edible renewable karanja (Pongamia Pinnata) oil, determination of BD properties and influence of BD on engine performance and emissions. Bangladesh imports 2.4 million metric ton (MT) DF each year [M.N. Nabi, M.S. Akhter, K.M.F. Islam, Prospect of biodiesel production from jatropha curcas, a promising non edible oil seed in Bangladesh, International Conference on Mechanical Engineering (ICME, Dhaka, Bangladesh) Proceedings 2007, paper no. ICME07-TH-06. ]. It has 0.32 million hectare of unused land [M.N. Nabi, S.M.N. Hoque, M.S. Uddin, Prospect of Jatropha curcas and pithraj cultivation in Bangladesh, Journal of Engineering and Technology, IUT, Dhaka, Bangladesh, 7 (1) (2009) 41–54. ]. It has been found that cultivating of karanja plant in such unused land; Bangladesh can reduce DF import by 28%. Karanja methyl ester (KME), which is termed as BD, has been produced by well-known transesterification process. The properties of B100 (B100) and its blends were determined mainly according to ASTM standard and some of them were as per EN14214 standard. The Fourier transform infrared (FTIR) analysis showed that the DF fuel contained mainly alkanes and alkens, while the B100 contained mainly esters. The gas chromatography (GC) of B100 revealed that a maximum of 97% methyl ester was produced from karanja oil. Engine experiment result showed that all BD blends reduced engine emissions including carbon monoxide (CO), smoke and engine noise, but increased oxides of nitrogen (NOx). Compared to DF, B100 reduced CO, and smoke emissions by 50 and 43%, while a 15% increase in NOx emission was observed with the B100. Compared to DF, engine noise with B100 was reduced by 2.5 dB. [Copyright &y& Elsevier]

This paper describes the biodiesel production from waste cooking oil (50% (v/v) olive oil/sunflower oil) in an oscillatory flow reactor (OFR) in batch mode. We mainly focused on the characteristics of the biodiesel and its performance as a fuel. First at all, we verified that biodiesel yield in OFR was higher than in stirred tank reactor (STR) under the same experimental conditions, and that composition and properties of the resulting biofuel did not depend on reactor type. Besides, biodiesel production in OFR took half the time than in STR. Subsequently, we modify some OFR operational parameters to assess their influence on biodiesel yield. The most suitable conditions were found to be 6:1 methanol to waste cooking oil molar ratio, 0.67 Hz oscillation frequency and 30 min reaction time. Finally, the biofuel obtained was tested in a 2.0 TDI 140 hp EURO4 engine installed on an engine test bench. Specific fuel consumption, particle size distribution and concentration of exhaust gas sample pollutants and were analysed running with commercial diesel, 50% (v/v) diesel/biodiesel blend (B50) and biodiesel (B100) in order to ensure the viability of using this biofuel in vehicle engines. [ABSTRACT FROM AUTHOR]

Economically viable microalgal biodiesel production is unrealistic and unsustainable owing to expensive harvesting or dewatering techniques. Hence, immense and meticulous exploration of harvesting process is essential to identify knowledge leads by which suitable harvesting technique could be ascertained for lucrative biodiesel production. With this in view, this review aims to collate and highlight the spectrum of harvesting techniques applied to microalgae, i.e., conventional – modern, high cost- inexpensiveness, energy efficient- energy consuming process. At the outset, global energy outlook and demand had been critically addressed, and the scientific ways to tackle or satiate the fuel demand had also been highlighted in this reveiw. This review manuscript has thrown widespread light on the physical harvesting methods namely centrifugation, sedimentation, filtration, flotation and technical advantages thereof. Due to the energy-intensive and cost barrier of physical harvesting techniques, chemical methods entailing organic, inorganic, and electroflocculation have come to limelight and in this regard, microalgae used, floc recovery and the dose of flocculants have been compared and presented in detail. Further, state of the art harvesting techniques viz., bioflocculation by microalgae/bacteria, flocculation by pH adjustment, and magnetic nanocomposite based microalgal harvesting had been critically articulated. Besides discussing the several methods, this paper has summarized the key challenges in conventional and advanced harvesting techniques and also provided the scope thereof. Hence, the key suggestions and findings given in this manuscript would positively offer a well-defined roadmap in choosing foreseeable harvesting technology for cost-effective microalgal biofuel development. [ABSTRACT FROM AUTHOR]

This paper deals with biodiesel production from corn oil as a feedstock via the transesterification and esterification reactions. To date, corn oil has not been considered a viable biodiesel feedstock because of its high edible value and relatively high price, but some industrial corn processing co-products, such as corn germ and dried distillers grains with solubles (DDGS), have potential for this application after the extraction of corn distillers oil (CDO). Here, after brief discussion of the issues related to corn botany, cultivation, and use, as well as the corn germ and oil composition, properties and use, the methods of corn processing for germ and DDGS recovery are presented. In addition, the mechanical and solvent extraction techniques for oil recovery from whole ground corn kernels, germs, and DDGS are considered. Furthermore, biodiesel production from corn oil, waste frying corn oil, and CDO is critically analyzed. It is expected that further investigation will be directed toward developing simpler, more effective and energy-saving technologies for biodiesel production from corn oil-based feedstocks, especially from CDO. The integration of biodiesel production directly into corn-based ethanol production will advance the overall economy of industrial plants. Furthermore, the fuel properties, performances and exhaust gas emissions of corn-based biodiesel and its blends with diesel fuel are discussed, taking into account the biodiesel quality standards. Finally, issues related to the environmental and socio-economic impacts of corn-based biodiesel production and use are also tackled. [ABSTRACT FROM AUTHOR]

The initial aim of the paper is to dramatically improve the pretreatment stage of biodiesel production, which converts problematic free fatty acids to fatty acid methyl esters, by introduction of a microbubble mediated reactive distillation stage instead of acid pretreatment. This will shift the conventional esterification process towards completion with a yield higher than 80%, even without high excess methanol. Application of ozone microbubbles has the advantage over acid gas catalysis in that it gives higher conversion and leaves no catalyst residue and requires no further catalyst recovery separation steps (a “phantom” catalyst). Unreacted ozone breaks down into oxygen, so the off-gases are just a humid air stream that can be vented. Importantly, ozonolysis breaks carbon–carbon double bonds into aldehydes and carboxylic acids. Many ester species were found after contacting the feedstock with ozone-rich microbubbles, depending on the molecular structure of the alcohols for the ozonolysis of oleic acid with alcohols, i.e., methanol, ethanol, n -propanol, iso-propanol, and n -butanol. In the case of ozonolysis of used cooking oil mixed with methanol, the results from the GC–MS show that all saturated free fatty acids (including palmitic acid, stearic acid, and myristic acid) are converted to methyl esters within 20 h of 60 °C ozonolysis , whereas trace amounts of these chemicals remain at lower temperatures. The results also show that the conversion of oleic acid to form oleic acid methyl ester is 91.16% after 32 h of ozonolysis at 60 °C. Therefore, the free fatty acid content in used cooking oil is less than 1.33%, which makes it suitable as a reactant for biodiesel production via transesterification. However, this result is different from the result provided by ASTM D974 in that the acid numbers decrease dramatically by 25% at the beginning of ozonolysis followed by a plateau. Moreover, if the fluidic oscillator is used to generate bubbles in ozonolysis of oleic acid mixed with methanol, the results show that the yields of ozonolysis product 1-nonanal increase by 30%. This observation means that ozonolysis of oleic acid is relative to the specific interfacial area, and favoured at low liquid temperatures. [ABSTRACT FROM AUTHOR]

This paper overviews the technological, technical, economic, environmental, social, toxicological and human health risk considerations of biodiesel production and use. The future efforts in the technological domain should be directed towards low–cost and non–edible feedstocks, advanced technologies with reduced overall production costs and profitable production capacity. Process innovations that include new more active and stable catalysts, advanced reactors, continuous operation, lower energy inputs, better energy balance and lower GHG emissions and produce low or no wastes can lead to more efficient biodiesel production. Environmentally sustainable biodiesel production requires that sustainability standards cover direct and indirect impacts on the environment, i.e. soil, water and air. The combination of technological with economic, social and environmental issues will increase biodiesel benefits and may lead to integrated biorefineries capable of producing sustainable biodiesel and other valuable chemicals. Government policies will be the primary driving force for further increases in biodiesel production. Increased cooperation among governments and various stakeholders is needed to develop and apply corresponding sustainability criteria in a consistent way worldwide as soon as possible. [ABSTRACT FROM AUTHOR]

This paper presents a conceptual design, simulation and techno-economic assessment of an energy self-sufficient process to produce 10,000 t per year of biodiesel using supercritical methanol and propane as cosolvent. A suitable heat-integrated design of the process was performed using a part of the produced biodiesel (7.4 wt.%) to achieve the energy self-sufficiency for the plant. The simulations were performed by Aspen Plus considering a continuous multitubular reactor operating at 280 °C, 128 bar, methanol-to-oil molar ratio of 24, propane-to-methanol molar ratio of 0.05, and a residence time of 9.7 min. The use of flash separators instead of distillation columns for methanol and propane separation contribute significantly to reduce the energy requirement, with respect to other studies. Final products are high purity of methyl esters (99.8%) and glycerol (96.4%). The economic analysis of the biodiesel plant resulted in a break-even point for the biodiesel selling price of 0.479 €/kg (at 10% rate of return), so the process can compete with the existing alkali and acid catalyzed processes. [ABSTRACT FROM AUTHOR]

Biodiesel is an important bridging biofuel for reducing greenhouse gases (GHG). In 2015, Germany introduced a new GHG based quota scheme for biofuels. However, the use of default GHG values for rapeseed cultivation could provide inaccurate for specific regions and locations. Therefore, the aim of this paper was to use RELCA (a REgional Life Cycle inventory Approach) to assess the regional and spatial variation of GHG emissions associated with biodiesel production in Central Germany and to compare these results with the default values of the Renewable Energy Directive (RED), as well as to identify potential mitigation options for biodiesel production. The RELCA simulations indicated GHG emissions of 31.9–39.83 CO 2 eq./MJ, with emission magnitude changing between biodiesel configurations due to their locations within the CG region. In comparison with typical RED values for biodiesel, the CG simulations showed 13–31% greater mitigation potential. The results also indicated that the configuration of biomass and conversion plant needs to be assessed to develop the most appropriate mitigation strategies. Current GHG mitigation strategies are limited to the energy sector, allowing leakages within the agricultural sector. Therefore, for more spatially targeting GHG accounting to be implemented, sustainability certification should be expanded to other biomass markets. [ABSTRACT FROM AUTHOR]

Biofuel production is not cost competitive and thus requires governmental intervention. The effect of the institutional framework on the development of the biofuel sector is not yet well understood. This paper aims to analyze how biofuel production and production capacity could have evolved in Germany in the period 1992–2014. The effects of an agricultural policy intervention (liberalization of the agricultural market) and a bioenergy policy intervention (a tax on biodiesel after an initial exemption) are explored. Elements of the Modeling Agent systems based on Institutional Analysis (MAIA) framework, complex adaptive systems (CAS) theory, and Neo Institutional Economics (NIE) theory were used to conceptualize and formalize the system in an agent-based model. It was found that an early liberalization of the agricultural market led to an under-production of biodiesel; a late liberalization led to the collapse of biodiesel production. An early introduction of the biodiesel tax led to stagnation in biodiesel production and production capacity; a late introduction led to an increase in sunk costs provided that the biofuel quota is binding. Also, a lack of agents’ adaptation mechanism to forecast prices led to a decrease in patterns of biodiesel production when an external shock was introduced in the system. In sum, we argue that system behavior is influenced by individual behavior which is shaped by institutions. [ABSTRACT FROM AUTHOR]

A multivariate approach was used for classification of fuel blends using the combined information from Fourier Transform Infrared Spectroscopy (FTIR) and stable carbon isotopes analysis by Isotope Ratio Mass Spectrometry (IRMS). Linear Discriminant Analysis (LDA) and Partial Least Squares Discriminant Analysis (PLS-DA) were applied to the classification of biodiesel/diesel fuel blends containing 0–100% (v/v) of biodiesel. The LDA and PLS-DA methods were able to discriminate samples ranging from 10% to 100% biodiesel (v/v) using the combined information from FTIR and IRMS. Since the global trend is toward a gradual increase in the percentage of biodiesel in fuel blends, the technique presented in this paper could be an important development in improving the traceability and identification of different raw materials used in biodiesel production. [ABSTRACT FROM AUTHOR]

To promote microbial oils as the feedstock for biodiesel preparation, developing an advanced cell treatment technology, especially suitable for treating water-containing microbial feedstock is very important. A novel method based on using formic acid assisted with small amounts of hydrochloric acid, to treat water-containing microalgae and extract lipid subsequently, is proposed in this paper. Effect of several factors on mixed acid treatment of Chlorella protothecoides was investigated systematically. It was found that the dosage of formic acid and hydrochloric acid, liquid/solid (l/s) ratio and temperature had a significant influence on lipid extraction from water-containing microalgae. Under the optimum condition of formic acid dosage 5.57 g/g (based on the weight of dried microalgae cell, the same below), hydrochloric acid dosage 0.1 g/g, liquid/solid (l/s) ratio10:1 and temperature 100 °C, the total lipid yield and FAME (Fatty Acid Methyl Ester) yield reached 45.6% and 85.8% respectively. This process allowed water content of wet biomass reaching 82.1%. Further study revealed that the process was suitable for the treatment of different microalgae materials. The results indicate that this mixed acid treatment is very promising for using wet microalgae as the feedstocks for biodiesel production. [ABSTRACT FROM AUTHOR]

Concern in relation to creating environmental protection policies is increasing, particularly with regard to the reuse of waste for power generation. In this context, biodiesel production from waste cooking oils could play an important role. Biodiesel is a biofuel that can be produced from saturated fatty raw material discarded by restaurants, such as oils and fats used for cooking processes. This paper describes a biodiesel production plant installed at Pinheira Beach in the State of Santa Catarina, southern Brazil and aims to discuss the environmental, social and economic impacts by analyzing the biodiesel production by life cycle assessment (LCA), relationship with the emission of greenhouse gases. The plant is run by an association and is aimed at promoting the recycling of waste cooking oil from restaurants and residences in the area and, at the same time, enables the continuity of artisanal fisheries in the region. The transesterification production process was used to convert waste cooking oils into biodiesel using basic catalysis in the presence of methanol. A batch system with the capacity to produce 200 L of biodiesel per day was adopted. The data obtained for the biodiesel produced at the plant were 879.2 kg m −3 density, 495.74 mg kg −1 water content, 94.38% ester content, and 1.5 mg.kg −1 sodium plus potassium. Related to the Life Cycle Assessment the results demonstrate that the category that most contributes to the emissions generated in biodiesel production process is the collection stage with 92.10% contribution, presenting a significant difference to the productions stage which contributed 7.9%. The plant provides environmental, social and economic gains for the community, for instance, increased income for the associates and fishermen, environmental education in schools, and cooking oil recycling opportunities. [ABSTRACT FROM AUTHOR]

This paper presents a review on microalga Botryococcus braunii ( B. braunii ) with an emphasis on lipid production for possible industrial commercialization in biodiesel production. Summarizing the nature of this alga is fundamental to establish the detail environment conditions for optimal biomass growth and the production of lipids, as well as upstream processing technologies for biodiesel production. This study focuses the attention on identifying possible avenues for further investigation in the design of cultivation systems and the integration of process technologies at industrial scales. The advantages and disadvantages of biodiesel production processes based on these algal lipids are also analyzed. A particularly promising process involving B. braunii combines flue gas and wastewaters to produce lipids, converting them to biodiesel by supercritical (SC) direct trans/esterification (esterification followed by transesterification). We conclude that such processes using B. braunii have considerable potential for the production of cleaner and more efficient biodiesel than current methods, reducing the environmental impact of fossil fuel use. [ABSTRACT FROM AUTHOR]

Developing technologies for the production of alternative fuels from biorenewable resources is a field of interest for many researchers. Adequate substitute to diesel fuel is biodiesel that is synthesized through the transesterification of vegetable oils or animal fats and fulfilled the international standards. Ionic liquids (ILs) and deep eutectic solvents (DESs) have gained tremendous attention for their use in biodiesel production because of environmental benefits and process improvements. The present work overviews the use of ILs and DESs in the reaction and purification steps of biodiesel production processes where they are used as catalysts, cosolvents and extracting solvent. In addition, the possibilities of recycling and reusing of ILs and DESs are pointed out. Moreover, optimization and kinetic studies of biodiesel synthesis in the presence of ILs or DESs are discussed. The use of novel technologies combined with ILs or and DESs are also considered. Therefore, the present paper highlights the promising uses of ILs and DESs in biodiesel production in the future. [ABSTRACT FROM AUTHOR]

This paper discussed the inherent safety assessment of biodiesel production pathways from the perspective of flammability parameter. The NuDIST technique for flammability scores calculation is used in the case study. Ranking between the productions pathways involved was calculated by considering all chemicals in the route as a mixture instead of individual components. Aside from that, mass fractions of the chemicals involved were used as weightage factor in order to determine the main contributors to the largest hazards in the process route. Four biodiesel production pathways were used as case study. According to the inherent safety assessment done, the acid-catalyzed transesterification using fresh vegetable oil (PP4) pathway is the most hazardous route with the highest assessment score of 15.59 while the enzymatic transesterification using fresh vegetable oil (PP2) pathway is the safest route with the lowest assessment score of 1.39 in term of flammability parameter. The case study shows that the amount of chemicals existed in the process as well as their flammability characteristic, plays an important roles in determining the main contributors to the largest hazards in the route. In this work, mass fractions for every chemical were used as the weightage factor which helps in identifying the main contributors to hazards with more accuracy. A chemical with high flammability score but existed in low amount in the process might not be as hazardous as a chemical with low flammability score but existed in huge amount in the process as shown by methyl oleate and methanol in the base-catalyzed transesterification using fresh vegetable oil (PP3). [ABSTRACT FROM AUTHOR]

This paper is concerned with the monitoring of a biodiesel production process, more specifically with the monitoring of the esterification of grease trap wastes, a low quality feedstock for biodiesel production typically characterized by its high content of Free Fatty Acids (FFAs). The esterification takes place in a jacketed Continuous Stirred Tank Reactor (CSTR). A reset observer is designed and applied in order to provide on-line estimation of the concentration of FFAs from temperature measurements within the CSTR. In addition, the proposed reset observer is compared to two other observers (classical fuzzy observer and extended Kalman filter). According to a multiple range test conducted for analyzing the estimation error, the monitoring task for the process under study has been better fulfilled by the reset observer which is able to update the estimation results every instant when the measurements were available. [ABSTRACT FROM AUTHOR]

Alumina-supported potassium oxides are promising catalysts for the transesterification reaction of vegetable oils for biodiesel production. Various potassium compounds Al 2 O 3 -supported were prepared via impregnation method. Potassium oxide (K 2 O) is a good candidate for a solid base catalyst from an economical point of view. In the present work, we reviewed K 2 O catalyst for the vegetable oil transesterification based on a variety of related research papers. The potassium compounds supported in catalysts, KOH/Al 2 O 3 , KNO 3 /Al 2 O 3 , KI/Al 2 O 3 , KF/Al 2 O 3 and K 2 CO 3 /Al 2 O 3, were optimized through various reaction parameters, such as: amount of catalyst, molar ratio of oil to alcohol, reaction time and temperature. Yields and conversions from various catalytic systems applied for biodiesel production were also compared. Among the catalysts studied, the KF/Al 2 O 3 showed higher catalytic activity and a small amount of catalyst requirement in the transesterification reaction, indicating that it can be applied as a potential catalyst in the industry. [ABSTRACT FROM AUTHOR]

Present work deals with the ultrasound-assisted biodiesel production from low cost, substantial acid value kusum ( Schleichera triguga ) oil using a two-step method of esterification in presence of acid (H 2 SO 4 ) catalyst followed by transesterification using a basic heterogeneous barium hydroxide (Ba(OH) 2 ) catalyst. The initial acid value of kusum oil was reduced from 21.65 to 0.84 mg of KOH/g of oil, by acid catalyzed esterification with 4:1 methanol to oil molar ratio, catalyst concentration 1% (v/v), ultrasonic irradiation time 20 min at 40 °C. Then, Ba(OH) 2 concentration of 3% (w/w), methanol to oil molar ratio of 9:1, ultrasonic irradiation time of 80 min, and temperature of 50 °C was found to be the optimum conditions for transesterification step and triglyceride conversion of 96.8% (wt) was achieved. This paper also examined the kinetics as well as the evaluation of thermodynamic parameters for both esterification and transesterification reactions. The lower value of activation energy and higher values of kinetic constants indicated a fast rate of reaction, which could be attributed to the physical effect of emulsification, in which the microturbulence generated due to radial motion of bubbles, creates an intimate mixing of the immiscible reactants causing the increase in the interfacial area, giving faster reaction kinetics. The positive values of Gibbs-free energy (Δ G ), enthalpy (Δ H ) and negative value of entropy (Δ S ) revealed that both the esterification and transesterification were non-spontaneous, endothermic and endergonic reactions. Therefore, the present work has not only established the escalation obtained due to ultrasonication but also exemplified the two-step approach for synthesis of biodiesel from non-edible kusum oil based on the use of heterogeneous catalyst for the transesterification step. [ABSTRACT FROM AUTHOR]

The industrial scale production of biodiesel, the most common biofuel, requires innovative solutions to become more and more competitive with a reduced environmental impact. Microalgae are the most promising feedstock for biodiesel production since they are grown on non-arable areas and reduce the greenhouse gas emissions as well. The oil extraction is the competitiveness bottleneck, largely impacting the overall process cost. Oil extraction using ionic liquids is considered a promising technique, which has the chance to become a benchmark for large scale applications. In this paper a novel process simulation of ionic liquid operation is developed, implemented by Aspen Hysys V7.3 ® . The chosen ionic liquid is Butyl-3-methylimidazolium chloride, a green solvent; since it is a non-conventional compound, a method to compute its properties through a thermodynamic model is provided. Moreover, a process scheme has been set up and simulated, composed of a lysis reactor, in which the ionic liquid is added for oil extraction, and a three phase separator, with recycle lines and several heat exchangers for heat recovery. Mass and energy balances have been carried out. The main results allowed to calculate the recovered oil as a function of the ionic liquid to dry biomass weight ratio (with assuming a bio-oil extraction yield of 100) and as expected, the bio-oil recovery yield increased at decreasing temperature. However, a complete recovery is not feasible, due to the physical constraints in the thermodynamic model hypotheses. Albeit some simplifying hypotheses for the thermodynamic properties, the novelty of this work is that it reports results of a process simulation, providing indication for industrial technological implementation coming from a professional tool for process simulation and control. [ABSTRACT FROM AUTHOR]

The problem of defining efficient and environmentally compatible short-term agricultural plans for biodiesel exploitation is dealt with in this paper with a multi-objective modelling framework. To optimally use local resources, the first phase of the plan consists in the analysis of land and climate features in order to evaluate which energy crop can be successfully grown. This phase is performed at local scale using GIS (geographic information system) data and software. The second phase consists in the formulation of a multi-objective mathematical programming problem. Using the land to be cultivated in each parcel with each crop as decision variables, we solve a three objectives problem: the maximization of the net energy produced, of the greenhouse gases avoided with respect to conventional fossil fuels and of the diversity of the energy crop mix. The last is quantitatively measured using a well-known biodiversity index, which allows to study the trade-off between a more varied crop mix and the other two objectives along the frontier of Pareto efficient solutions. The proposed methodology is applied to a region of Mato Grosso, Brazil, where biodiesel is produced from oleaginous crops. [ABSTRACT FROM AUTHOR]

The expected depletion of natural petroleum resources in the near future and pollution of the environment due to excessive carbon dioxide emissions by fossil fuel and its adverse effect on global warming constitute two major problems facing the whole world. In view of these problems, much research work is now directed worldwide to find fuels alternative to those derived from petroleum which should be renewable and more environmentally friendly fuels. Biodiesel fuel which is a blend of fatty acid esters with alcohols is considered the most suitable alternative fuel for diesel engines. In this scope of research work, a previous study (Soliman et al., 2013) has been made to explore the opportunity of utilizing the fatty acids that can be obtained from the waste of edible oil industry in Egypt to produce biodiesel fuel by direct esterification with methanol as well as ethanol in the presence of sulfuric acid as a catalyst. This paper is a continuation of that work where two other alcohols of a chain length longer than ethanol have been used being propanol and butanol. The performance of a diesel engine running using a 50% blend of regular diesel fuel and each of the two biodiesels prepared was compared to that using regular diesel fuel. The results have shown that the brake specific fuel consumption (BSFC) and the brake thermal efficiency at full engine loading were almost the same in all cases. This indicates that the produced fuel could be used as an efficient fuel substitute for diesel engines. By comparing the results of the present work to those reported in our previous work, it appeared that methanol which has the shortest carbon chain length is the most recommended in view of the brake thermal efficiency of a diesel engine at full loading. [ABSTRACT FROM AUTHOR]

This paper presents the use of a commercial FlowSynth microwave reactor for the continuous production of biodiesel from palm oil. A high ester content of 99.4% can be obtained in only 1.75 min residence time at a methanol to oil molar ratio of 12, a microwave heating power of 400 W, reaction temperature of 70 °C and NaOH catalyst loading of 1%wt of oil. The process energy consumption has also been investigated in order to assess the potential advantages of using microwave irradiation for biodiesel production. The energy consumption of palm oil transesterification as low as 0.1167 kWh/L of biodiesel was required, proving that microwave reactors need less energy consumption as compared to conventional processes. Moreover, all main biodiesel properties are in accordance with EN/ASTM standards. [ABSTRACT FROM AUTHOR]

In this paper, we analyse the opinions, attitudes and willingness of consumers to pay for biodiesel as an alternative to diesel in Barcelona province. Data were gathered from face-to-face structured questionnaires from 300 diesel car owners/users that regularly purchase fuel. A variation of the traditional choice experiments (CE) was used by excluding the price attribute from the design. In a subsequent contingent valuation (CV) exercise, respondents were asked to state their maximum willingness to pay (WTP) for their preferred choice sets using the “payment card” format. The relative importance of the attributes and levels were calculated by estimating a random parameter logit model. The results demonstrated, contrary to the literature in Spain, that consumers were not willing to pay for biodiesel, especially when its production may negatively affect food prices. The main limitation was that car manufacturers do not recommend its use as it may lead to engine failure. The public authorities are asked to work jointly with the automotive industry to address this drawback. [ABSTRACT FROM AUTHOR]

Over the last century, the consumption of fossil fuels has increased significantly, which led to a depletion of their reserves. Hence, the search for new alternative sources as biodiesel and hydrogen has become an attractive endeavor to meet world energy demand. In the production process of biodiesel, a proper choice of feedstock and catalyst has been the subject of studies in order to analyze the technical and economic viability of biodiesel production. Nowadays, studies are also directed to an energy-efficient use of glycerin. In this context, the present study aims to assess the simultaneous production of biodiesel and hydrogen. An exergetic analysis methodology is use to identify irreversibilities in each component of the plant, as well as quantify which ones present higher and lower efficiencies. As a result, it is found that the highest irreversibility is associated with the transesterification process and the largest exergetic efficiencies are promoted by the washing processes, the methanol recovery and the catalyst removal. Finally, it is possible to conclude that the simultaneous production of Biodiesel and Hydrogen is a technology which offers technical viability and leaves a room for thermoeconomic and ecological studies to be carried out in the future looking for the complementation of the results obtained in this paper. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the physical and chemical properties of Moringa oleifera biodiesel and its blends of 10%-90% by volume with petro-diesel according to the American society for testing and materials (ASTM D6751) standards and European standards (EN 14214). It was found that when Moringa biodiesel is blended with diesel fuel, all its fuel properties such as kinematic viscosity (KV), density (D), calorific value (CV), flash point (FP), cloud point (CP), pour point (PP), and cold filter plugging point (CFPP). For example, B10 reduce the viscosity of B100 from 5.05 mm 2 /s to 3.54 mm 2 /s (1.4:1). Then developed empirical models of properties are show high regression value (R 2 ) between properties and MOME-diesel blend. It is believed that the results obtained and empirical model proposed in this study will help the researchers to predict the properties of biodiesel-diesel blend which are important parameters to design the fuel system of biodiesel engine. [ABSTRACT FROM AUTHOR]

Today, the price of glycerol has dramatically dropped due to its oversupply from biodiesel production as well as oleochemical industry. Thus, it is essential to develop processes to transform bioglycerol into commercially valued products which is important to ensure sustainability in the biodiesel and oleochemical industries. One possibility is to transform it in propanediols, which have numerous applications such as food additives, raw material in pharmaceutical and cosmetic industries. In this paper, methods of conversion of glycerol into 1,3-propanediol are reviewed and discussed in detail. [ABSTRACT FROM AUTHOR]

Driven by high energy demand and environmental concerns, biodiesel as a substitute for fossil fuels is recognized to be promising renewable and clean energy. The increase in the biodiesel plant dramatically leads to the oversupply of its by-product glycerol in the biodiesel industries. Developing new industrial uses for glycerol is essential to increase the net energy and sustainability of biodiesel. Moreover, glycerol has great potential to be converted into marketable and valuable chemicals. The conversion of glycerol to glycerol carbonate (GC) has been extensively studied and transesterification of glycerol to GC has been proven to be the most promising route. Aimed to reveal the underlying mechanism of this successful conversion path, this paper reviews the chemo- and biocatalytic transesterification of glycerol with different carbonates sources. Also, a detail elucidation of the influence of the catalysts and operating conditions on the GC yield is included to provide an insight into the process. In addition, the future direction of glycerol carbonate production via catalytic transesterification is provided in this review. [ABSTRACT FROM AUTHOR]

An increase in glycerol production is expected because of the increasing use of fuel additives such as methyl esters. This increase can enhance the importance of glycerol as a cheap raw material for producing value-added products. Future scenarios for worldwide glycerol market will mostly be related to the supply and demand of glycerol and its application in other industries. Much research have been developed and continuously investigated to convert low-value glycerol using different strategies and approaches. Due to the unique structure of glycerol, properties and renewability feature of it, new opportunities for the transformation of glycerol into high-valued chemicals have merged in recent years. This paper provides a review on glycerol, global market of glycerol and conversion of glycerol to value-added products. Catalytic etherification of glycerol to value-added products such as polyglycerols is particularly reviewed. [ABSTRACT FROM AUTHOR]

This paper provides a critical review of the palm biodiesel landscape in Malaysia. The palm industry is a key source of revenue for the country, where in 2009 the industry was responsible for generating 8% of the gross national income per capita. The interest in palm-based biodiesel can be traced back to the early 1980s however it was only in 2006 that Malaysia officially formulated its first National Biofuel Policy as a strategic government intervention to drive development and implementation of palm biodiesel as substitute to regular fossil-based diesel. As at January 2013, the implementation of the biodiesel mandate (at 5% concentration) has been limited to the Klang Valley central region only. But there are plans for a much wider roll-out and at higher concentration blends in 2014. The policy in its current form assumes that all biofuels are sustainable and therefore fails to provide assurances that the fossil diesel will be replaced by a more sustainable energy source. Here it has been argued that a market-based policy approach would be better than a technology-forcing mechanism. [ABSTRACT FROM AUTHOR]

It is well known that energy consumption is rapidly increasing due to population growth, higher standard of living and increased production. Significant amounts of energy resources are being consumed by the transportation sector leading to the fast depletion of fossil fuels and environmental pollution. Biodiesel is one of the technically and economically feasible options to tackle the aforesaid problems. Biodiesel is produced mainly from edible oils. However, it is believed that the extensive use of edible oils for biodiesel production may lead to food shortages in most of the developing countries. Therefore, the aim of this paper is to review the necessity and potentiality of the non-edible oils and to identify the emerging technologies to produce biodiesel. Special attention has been paid to the impact of biofuels on agricultural commodity prices and the food-fuel debate. [ABSTRACT FROM AUTHOR]

Abstract: In the US, biodiesel producers usually follow the 19.8:1 methanol-to-FFA molar ratio for free fatty acid (FFA) esterification, as suggested by the National Renewable Energy Laboratory (NREL) without optimization studies. In this paper, both laboratory studies and industrial practices of the esterification process were compared, and an optimization study of a used vegetable oil with 5% FFA was conducted. The optimal conditions of this oil, i.e., methanol-to-FFA molar ratio of 40:1, and sulfuric acid usage of 10%, fell out of the suggested range of 19.8:1. The activation energy of the esterification reaction is 20.7kJ/mol at the optimized condition and 45.9kJ/mol at the 19.8:1 methanol to FFA ratio. It was found that the 19.8:1 methanol-to-FFA molar ratio worked well only within the FFA range of 15–25% while the suggested 5% sulfuric acid worked well only within the FFA range of 15–35%. Outside these ranges, especially at FFA levels less than 15%, optimization study is necessary. Regression models of methanol and acid dosing have been utilized in two industrial scale biodiesel producing facilities and have successfully reduced the FFA level to less than 0.5%. [Copyright &y& Elsevier]

Abstract: The story of Jatropha curcas (Jatropha) was started in 2003 when the Planning Commission of India decided 20% blending of Jatropha oil (biodiesel) in petroleum diesel by 2010 and 30% by the year 2030. After that China, Japan, Belgium, Brazil, Tanzania, Mexico, Thailand, Malaysia, Philippines, and East and South Africa have set their own plans to blend Jatropha oil in petroleum diesel. It is not unexpected that almost every paper about Jatropha starts its introduction with the energy, environment and economic benefits and wishful thinking of reducing global warming. Unfortunately, Jatropha could not succeed so far in energy sector as expected, for which it was the most popularized energy crop. Many of the actual investments and policy decisions on Jatropha have convincingly been made without any scientific and technological backup. It has become clear that the positive claims on Jatropha are numerous which have popularized it as a potential source in biodiesel production but many of them still remain as theoretical assumptions and have not been verified yet practically. This letter reports briefly the status of past hopes to ground reality on the basis of what a few scientific studies on Jatropha. [Copyright &y& Elsevier]

Abstract: Biomass has become important as an alternative to fossil fuels and as a means to decrease greenhouse gas (GHG) emissions, particularly in tropical regions such as Brazil. Therefore, the demand for energy crops has increased strongly, and among such crops, palm oil is distinctive because of its productivity and well-developed production techniques. This paper intends to evaluate crude palm oil's GHG balance through a life-cycle assessment approach. This study is based on the average data of an ideal palm oil system in the northern region of Brazil. In the production of crude palm oil, a large amount of CO2 sequestration occurs during the growth of palm oil trees. In contrast, the greatest emissions are biotic CO2, which returns to the atmosphere and emissions from fertilizer production. The GHG balance of an oil palm plantation is approximately −208 kg CO2-equiv./1000 kg crude palm oil per year. [Copyright &y& Elsevier]

Highlights: [•] This paper presents the techno-economic of a production of biodiesel from JCO. [•] The results obtained 99.96% of biodiesel with 96.49% of pure glycerol. [•] This proved that biodiesel from JCO is the least expensive compare to other resources. [Copyright &y& Elsevier]

Abstract: The demand for petroleum has been rising rapidly due to increasing industrialization and modernization. This economic development has led to a huge demand for energy, most of which is derived from fossil fuel. However, the limited reserve of fossil fuel has led many researchers to look for alternative fuels which can be produced from renewable feedstock. Increasing fossil fuel prices have prompted the global oil industry to look at biodiesel, which is from renewable energy sources. Biodiesel is produced from animal fats and vegetable oils and has become more attractive because it is more environmentally friendly and is obtained from renewable sources. Glycerol is the main by-product of biodiesel production; about 10% of the weight of biodiesel is generated in glycerol. The large amount of glycerol generated may become an environmental problem, since it cannot be disposed of in the environment. In this paper, an attempt has been made to review the different approaches and techniques used to produce glycerol (hydrolysis, transesterification, refining crude glycerol). The world biodiesel/glycerol production and consumption market, the current world glycerin and glycerol prices as well as the news trends for the use of glycerol mainly in Brazil market are analyzed. The technological production and physicochemical properties of glycerol are described, as is the characterization of crude glycerol obtained from different seed oil feedstock. Finally, a simple way to use glycerol in large amounts is combustion, which is an advantageous method as it does not require any purification. However, the combustion process of crude glycerol is not easy and there are technological difficulties. The news and mainly research about the combustion of glycerol was also addressed in this review. [Copyright &y& Elsevier]

Abstract: This paper aims at the assessment of the methods of production of biodiesel from different types of used cooking oil. Researches into the productive chain of this type of biofuel were performed in Brazil while several scientific studies approaching processes of pretreatment and transesterification of waste cooking oil were analyzed with their possible variations: alkaline catalysis, acid catalysis, enzymatic catalysis and non-catalytic conversion techniques, highlighting the main advantages and disadvantages of each analyzed route. The use of alkaline catalysts in transesterification is the most common technique employed by the industry, being the KOH the most recommended catalyst for the reaction with waste cooking oil. When water and acidity contents are high, pretreatment techniques and other types of catalysts such as solid acids are recommended. Moreover, the economic benefits provided by used cooking oil were analyzed, indicating reductions of up to 45% of direct production costs compared to virgin oils, even with the additional costs of the pretreatment. Finally, the availability of raw materials was estimated, indicating that the used cooking oil would have potential to supply up to 13% of the demand for biodiesel in Brazil. [Copyright &y& Elsevier]