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The valorisation of the organic fraction of municipal solid waste (OFMSW) in the circular economy context is of outmost importance. This review aimed to examine the state-of-the-art valorisation technologies of OFMSW as resource for bioethanol and biodiesel. Firstly, feedstock mapping was performed, where high fluctuation of parameters was revealed. Considering the mean values, the stoichiometries of mechanically and source-sorted OFMSW are C 22 H 44 O 28 N and C 20 H 36 O 16 N, respectively. The substrate's mean carbohydrates (50%) and lipids (13%) contents reflect its potential in bioethanol and biodiesel production, respectively. As far as bioethanol is concerned, this paper critically reviewed the existing variance of second-generation bioethanol production methodologies from OFMSW revealing that high bioethanol yields (over 80%) could be achieved if the treatment steps of pretreatment, enzymatic hydrolysis and fermentation are synergistically compiled. To this end, bioethanol yield could benefit from suitable enzymatic blends. Furthermore, this paper discussed about different ways of oil extraction from OFMSW and various biodiesel production techniques. Soxhlet extraction combined with alkaline transesterification emerged as the most widely applied biodiesel production line from OFMSW. The novelty of this literature review lies in the integration of both bioethanol and biodiesel production processes, in a biorefinery concept that would allow the production of both biofuels along with that of biogas. This integration scenario rendered an energy efficiency expressed as energy content in products per energy in raw materials equal to 68%, proving that OFMSW is a feedstock that could meet the sustainability criteria for biofuels production. Image 1 • Up to date information on the composition of OFMSW. • Bioethanol production from OFMSW; pretreatment, hydrolysis, fermentation, stillage. • Biodiesel production from OFMSW; oil extraction, transesterification. • Bioethanol, biodiesel, biogas production from OFMSW under the biorefinery concept. • Integrated biorefinery exhibits various technical and energy benefits. [ABSTRACT FROM AUTHOR]

Increases in biodiesel production have led to a surplus of crude glycerol, which represents a major bottleneck in the biodiesel production chain and has created new challenges to its sustainable use. Although there is a wide range of potential uses for crude glycerol, they are limited by its degree of purity, which affects its physical, chemical and biological properties. This paper presents a review and analysis of patents related to the use of glycerol in the period from 1993 to 2015, showing the quantity and diversity of work related to the search for alternatives to add value to glycerol. It was found that 85.7% of the filed patents fell into four categories of applications: 1) manufacture of chemical products; 2) production of polymer compounds; 3) production of biofuels and biogas; and 4) purification and use of glycerol. In this regard, the development of new technologies for the use of glycerol, without the need for traditional purification steps, are fundamental. This paper portrays the efforts that have been made in this direction and the obstacles that still have to be overcome. [ABSTRACT FROM AUTHOR]

The diesel engine is being widely used in day to day life in both mobile and stationary applications. The main drawback is the release of harmful gasses like HC, CO, NO x and particulate matter into the atmosphere. This affects both human beings and environment to a great extent and should be controlled effectively. This paper reviews the works on the control of diesel particulate matter in both pre-combustion and post-combustion techniques employed in the past few decades. The initial part of this review will discuss particulate matter composition and its structure. Then the various physical processes involved in the formation of particulate matter are discussed. Effects of fuel composition and its structure on soot formation are reported. Hazardous effects of particulate matter on both human beings and the environment are reviewed. Use of biodiesel water emulsified fuel as a fuel to control soot formation is highlighted. This review also highlights control of particulate matter by varying injection parameters like injection pressure, injection timing and auxiliary air injection. Multiple fuel injections within the same cycle to control NOx and particulate matter are also discussed. The conventional control technique of particulate matter by using Diesel particulate filter and its types are also compared with the new technologies. Various regeneration concepts to burn the collected soot are also highlighted. The major part of this review focuses on pre-combustion techniques to control particulate matter. This review paper, it is hoped, will be very useful for the researchers working on the control of diesel particulate matter. [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]

Increasing in oil consumption and ridiculous prices has caused the urgency for the main global oil industry players to search new alternative fuels which is biofuels. Biodiesel is better option to replace the crude oil due to its similar characteristics and sustainable. This paper will review the biodiesel produced and implementation from palm oil in Malaysia and current engine research that related to palm oil. Precedency given to the palm oil as it is main raw stock for biodiesel produced in Malaysia. Among scopes of this paper are to discuss current issues related to the palm biodiesel production and specific use in diesel engines. Another issue that arisen for Malaysia is to promote the palm oil as the alternative fuel that meets the stringent regulations and standards in Europe and North America. This paper also briefly covers the continuous global biodiesel consumption trend including the constraints that faced by Malaysia for leading the global biodiesel market with the benefits and drawbacks of palm oil biodiesel as an alternate fuel compared to the other common biodiesel sources. [ABSTRACT FROM AUTHOR]

In recent years, alternative fuel studies have been conducted thoroughly by researchers through their experimental work. Depletion of fossil fuel raised the attention of researchers to investigate renewable energy sources such as biodiesel and alcohol. There is a lack of literature review study on the viability of alcohol acting as additive in biodiesel-diesel fuel blends. Thus, this review paper studies on the effects of various alcohol additives in biodiesel-diesel fuel blends on combustion behaviour, performance and emission characteristics of diesel engines. The physicochemical properties of alcohol and biodiesel are rigorously discussed, in which they are the main factors in determining the quality of the blended fuel. The aim of this paper is to identify the potential of alcohol fuel as an additive in the blended biodiesel and diesel fuel in correspond to the type of alcohol, blending ratio and engine operation conditions. Wide range of results from previous research studies with different types of compression-ignition engine, different engine operation conditions and varieties of alcohol-biodiesel-diesel fuel blending ratios were collected in this literature review study. Combustion behaviour such as coefficient of variations (COV), in-cylinder pressure, ignition delay, heat release rate and combustion duration are presented. Low cetane number and high latent heat of vaporization of alcohol cause a longer ignition delay, produce higher rate of heat release and lower in-cylinder pressure when compared with that of diesel fuel. Low density and viscosity of alcohol improve the spray characteristics and enhance air-fuel mixing process. In terms of engine performance analysis, the presence of oxygen in alcohol fuel promotes a more complete combustion; hence, resulting in an increase of thermal efficiency. In turn, emissions of carbon monoxide (CO), hydrocarbon (HC) and particulate matter (PM) are decreasing. [ABSTRACT FROM AUTHOR]

Global biodiesel production grew by 23% per annum between 2005 and 2015, leading to a seven-fold expansion of the sector in a single decade. Rapid development in the biodiesel sector corresponded to high crude oil prices, but since mid-2014, oil prices have fallen dramatically. This paper assesses the economic and policy factors that underpinned the expansion of biodiesel, and examines the near-term prospects for biodiesel growth under conditions of low fossil fuel prices. We show that the dramatic increase in biodiesel output would not have occurred without strong policy directives, subsidies, and trade policies designed to support agricultural interests, rural economic development, energy security, and climate targets. Given the important role of policy—and the political context within each country that shapes policy objectives, instruments, and priorities—case studies of major biodiesel producing countries are presented as a key element of our analysis. Although the narrative of biodiesel policies in most countries conveys win-win outcomes across multiple objectives, the case studies show that support of particular constituents, such as farm lobbies or energy interests, often dominates policy action and generates large social costs. Looking out to 2020, the paper highlights risks to the biodiesel industry associated with ongoing regulatory and market uncertainties. [ABSTRACT FROM AUTHOR]

In the last decade several scientific papers have dealt with the damages fossil fuels did to our environment. Carbon dioxide has been blamed the chief culprit since it is produced by the automobile fleet that uses diesel or gasoline as a fuel. As a result, several countries are implementing public policies aimed at the replacement of fossil fuels by renewable ones, such as biodiesel. Brazil has become one of them, since the biodiesel production has increased from 736 m 3 to 3,419,838 m 3 in less than ten years. Therefore, this paper intends to briefly review the literature on the history, evolution, and the environmental aspects of biodiesel in Brazil in order to show its positive economic impact on the Brazilian economy, in addition to showing how important this biofuel is to the environment by providing an overview of its advantages when compared to fossil diesel. [ABSTRACT FROM AUTHOR]

Due to the finite stock of fossil fuels and its negative impact on the environment, many countries across the world are now leaning toward renewable sources energies like solar energy, wind energy, biofuel, hydropower, geothermal and ocean energy to ensure energy for the countries development security. Biodiesel is one kind of biofuel that is renewable, biodegradable and has similar properties of fossil diesel fuel. The aim of this paper is to provide the substantial information on biodiesel to the researchers, engineers and policy makers. To achieve the goal, this paper summarizes the information on biofuel development, feedstocks around the world, oil extraction technic, biodiesel production processes. Furthermore, this paper will also discuss the advantages of biodiesel compared to fossil fuel. Finally, the combustion behavior of biodiesel in an internal combustion engine is discussed and it will help the researchers and policy maker and manufacturer. To determine the future and goal of automotive technology the study found that, feedstock selection for biodiesel production is very important as it associates 75% production cost. Moreover, the test of fuel properties is very important before using in the engine which depends on the type of feedstocks, origin country, and production process. Most of the researchers reported that the use of biodiesel in diesel engine reduces engine power slightly but reduces the harmful emission significantly. Finally, the study concludes that biodiesel has the potential to be used as a diesel fuel substitute in diesel engines to solve the energy and environment crisis. [ABSTRACT FROM AUTHOR]

Biofuels derived from algae can have lower impact on the environment and the food supply than biofuels produced from crops. The strain selection, cultivation method, culture conditions and the chemical composition strongly influences the production costs but also the engine's performance and the exhaust gas emissions. The scope of this paper is to make a critical review about the impact of the use of biofuels produced from (micro) algae to power diesel engines. There is a huge disparity in the amount of papers published for algae culture, oil extraction, and biodiesel production compared to reporting performance on diesel engines. This paper presents an analysis of the papers published in this specific field. Generally, a reduction of torque and power output is reported. A wide range of blends up to B50 but also pure biodiesel has been tested. The blend showing results closest to diesel fuel appears to be B20. Several pollutants can be reduced if biofuels from different strains are used but an increase in NOx is generally reported, associated to higher temperatures in the combustion chamber. The use of emulsions instead of blends or neat biodiesel reveals a promising alternative with important reductions of CO 2 and NOx. However, the few reports for engine tests present some contradictions, or are lacking important information about the experiments. The assessment of biodiesel produced from algae or microalgae is a field hardly explored and until today some reference papers contain contradictory results or non-well studied behaviors as this survey demonstrates. [ABSTRACT FROM AUTHOR]

Many researches have been carried out towards the reduction in noxious emissions from diesel engines. This paper reviews the studies on the outcomes of operating parameters discrepancy on the engine emission issues carried out by various authors in different diesel engines fuelled with biodiesel from different feedstocks. The main goal of this paper is to enlighten the momentous of injection parameters like injection timing and injection pressure on the engine emission characteristics. This paper touches upon the advancement and retardation methods of fuel injection timing and injection pressure to inspect the engine emission indicators such as carbon monoxide, hydrocarbon, oxides of nitrogen, smoke, particulate matter and carbon dioxide contents. Comparative evaluation has been conversed accompanied by apropos causes for the deviation of emission characteristics. [ABSTRACT FROM AUTHOR]

A pursuit of environment conservation as well as a fluctuated rise in diesel price has moved worldwide interests towards biodiesel, a kind of clean and renewable alternative fuel for the diesel engines. However, owing to heterogeneous mixing between the air and fuel, particle matter(PM) emissions have always been a main concern in the development of the diesel engines, especially in the face of continuously updated and progressively stringent PM emission regulation. Therefore, this paper sorts out and analyzes the studies published chiefly in scientific journals about particle matter emissions of the diesel engines used biodiesel or biodiesel/diesel blends as fuels compared with those from the traditional diesel fuels. The paper mainly includes the following sections. The first section deals with the fundamentals of particle matters from the biodiesel combustion including particle composition, physical and chemical properties. In the next, particle formation mechanism as well as PAH formation is introduced briefly. The effects of biodiesel property on particle emission are discussed in the third section. Then, the effects of operating parameters of the engines on PM emissions have been analyzed in the fourth section. After that, the influences of biodiesel blending on diesel particulate filter (DPF) and radiocarbon ( 14 C) analysis of biodiesel particles have been reviewed. At last, general conclusions are summarized and further research targets are proposed in this paper. [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]

This paper analyzes the performance and emissions of biodiesel from different feedstocks. The main goal of this paper is to provide information to the engineers, industrialists and researchers who are interested on biodiesel and to emphasise biodiesel as a promising alternative replacement for fossil fuels. A substantial number of literatures from highly rated journals in scientific indexes were cited preferentially since 2000. The performance and emissions indicators such as brake torque, brake power, BTE, EGT, BSFC NO x , PM, CO, CO 2 , HC and smoke density have been evaluated in comparison to pure diesel. The results showed that different sources of biodiesel feedstocks give different results to engine performance and emissions. Surprisingly some of the research yielded favourable results towards the biodiesel as compared to pure diesel. The study concluded that biodiesel can be used in compression ignition engine as a replacement of diesel fuel to fulfil the global energy demand. However, further research on about optimisation, cost-effectiveness and availability of biodiesel needs to be carried out to help ensure that biofuel will be able to fully replace fossil fuel. [ABSTRACT FROM AUTHOR]

This review paper presents the methods that have been used to date for the purification of crude biodiesel obtained by heterogeneous production processes. At first, a typical biodiesel production process using heterogeneous catalysts is shortly described, paying attention to the main processing steps. Then, possible impurities and their effects on the biodiesel quality are pointed out. The main part of this review paper deals with the traditional (wet and dry washing) and novel (membrane extraction, precipitation, complexation, simultaneous ion-exchange and precipitation as well as simultaneous biodiesel synthesis and purification) purification methods. These purification methods are compared with respect of their refining efficiency. A special attention is paid to their comparison regarding the type of raw materials used in biodiesel production. Furthermore, advantages and disadvantages of the crude biodiesel purification methods are emphasized. Finally, environmental aspects of crude biodiesel purification are highlighted. [ABSTRACT FROM AUTHOR]

Thermal power plants in India emit around 500 Mt of CO 2 annually. All of it is released into the atmosphere untreated. Microalgae, a third generation feedstock for bio-fuel emerges as a viable option for partly sequestering the emissions. Moreover, its carbon capture capacity of 4.8 kg CO 2 /kg biomass, which is very much as compared to terrestrial substitutes like Jhatropa curcas , enables to produce bio fuel hence adding value to the entire process. This paper intends to build upon this idea and come up with strategies to integrate bio fuel production and CO 2 sequestration with the existing thermal power plants. The raw materials needed for algal growth are available in the plant as elaborated in the paper. Thus the bio fuel produced can be routed back to power the plant consequently lowering the dependence on coal. This would help in putting a check on the carbon emissions thus making the existing systems more environmentally benign and suitable for long haul. This paper reviews currently employed carbon capture technologies and methods and comes up with a strategy to subsume carbon capture through microalgae with power plants of a certain capacity. 3 t/day is taken as the basis for calculations in the proposed flow sheet. An alternative of the above is also provided which substitutes the biofuel production with co-firing. This escalates the nitrogen content of flue gas but deescalates the investment. This brings down the capital investment in the plant but enhances N 2 content of flue gas. Carbon leakage is accounted for in a table of atomic balance. It takes care of input and output of carbon. The paper is inclined towards the conclusion that the Microalgae possess incredible potential and if tapped efficaciously could prove to be extremely helpful in these days of power and environmental crisis. [ABSTRACT FROM AUTHOR]

Nowadays, biodiesel is an alternative fuel to replace the existing petroleum-based diesel. The advantages of biodiesel are good combustion efficiency, high-lubricity, biodegradability and low toxicity. Biodiesel can be an alternate fuel to be used for running diesel engines. This paper is to present a comprehensive review on the past efforts to enhance and commercially improve the transesterification by using homogeneous base catalyst, e.g. sodium hydroxide or potassium hydroxide. By introducing heterogeneous base catalyst such as calcium oxide which was made from waste material such as chicken eggshell, quail eggshell and ostrich eggshell it may cater the excessive washing problem to remove the excessive reactants and glycerol. It is also an environment friendly way of recycling the waste eggshells; nevertheless, the NO x emission remains high – around 5–10% more than conventional diesel fuel. Thus, subsequently, this paper also discusses emulsification of biodiesel with water to investigate its influence on the overall diesel engine performance which includes a comparison study of gas emission from pure biodiesel, diesel and emulsion of biodiesel and water. Compared with conventional biodiesel, some of the notable advantages from this water emulsified biodiesel are the emission reduction of NO x , particular matter, unburned hydrocarbon and carbon monoxide. [ABSTRACT FROM AUTHOR]

Abstract: Biodiesel, an alternate and ecologically acceptable substitute for the conventional fuel, is usually produced from a wide range of edible vegetable oils, which are normally used for human consumption and whose prices are expected to increase in the future. In this regard, reliable and low-cost raw materials have increasingly drawn interest for biodiesel production, such as by-products of the meat-processing industries or waste animal fats. This paper provides a review of the different methods employed for biodiesel production from waste animal fats employing transesterification reaction. The aim of this paper is to present the exploitation possibilities of waste animal fats as low-cost feedstocks for biodiesel production. Also, the various methods for treatment of waste animal fats such as chemical (homogeneous and heterogeneous) and enzyme catalysis as well as non-catalytic processes were considered with emphasis on the influence of the operating and reaction conditions on the process rate and the ester yield. In depth discussions were given to the process optimization, kinetics and possibilities for improvement of biodiesel production from waste animal. [Copyright &y& Elsevier]

Abstract: In the view of rapid depletion of fossil fuels and rise in price of crude oil, there is emergent focus and need to search for alternative fuels. As we know that there is huge demand of diesel for transportation sector, captive power generation, agricultural sector and industrial sector, to accommodate those demands biodiesel is being viewed as a substitute for diesel. Biodiesel is an engine fuel that is prepared by chemical reaction of fatty acids and alcohol, which usually means combining vegetable oil with methanol in the presence of a catalyst (usually sodium hydroxide). But before using biodiesel as a substitute for engine fuel, there are two major problems associated, first one is “cold flow property of biodiesel” and second one is termed as “stability of biodiesel”. In this paper our main focus will be on cold flow property of biodiesel and its impact on engine performance. Some of the cold flow properties such as cloud point, pour point and cold filter plugging point are responsible for solidification of fuel causing blockage in fuel lines filters which further leads to fuel starvation in engine operation during starting operation. This paper also provides several remedial measures for improving the cold flow properties of biodiesel. [Copyright &y& Elsevier]

Abstract: Biodiesel is gaining acceptance in the market as fuel and lubricant. It is expected that biodiesel industries will rapidly grow worldwide in the coming years and information on biodiesel feedstock, production, and characteristics will be crucial than ever especially for those using vegetable oils as feedstock as these are currently the major sources for making biodiesel. In the present paper, a comprehensive review is reported on feedstock, production technologies, and characteristics of biodiesel. More specifically, selected available vegetable oils are explored as feedstock for biodiesel production. Production technologies including latest catalyst developments are discussed. Finally, biodiesel characteristics and parameters influencing the corresponding properties are revealed. Since this paper covers a wide range in biodiesel area, it serves as a general public education medium as well as a research reference for biodiesel production from vegetable oils. [Copyright &y& Elsevier]

Abstract: The energy security concern has been established as an alarming issue in context of petro diplomacy now-a-days. Global warming with rapid changes in climate, increase in price and depletion in reserve of fossil fuel are leading scientists to work toward alternative fuel. Biodiesel could be an answer for the alternative fuel, which is renewable, biodegradable, non-toxic and less polluting. This paper is comprised of fuel properties, engine performance and emission characteristics of commonly used different vegetable (jatropha, palm, coconut, cottonseed, sunflower, soybean and canola/rapeseed) based biodiesel derived from experimental results at different conditions performed worldwide. It can introduce a potential guideline to improve engine performance and emission characteristics using different biodiesels and their blends as well. This paper provides a comparative baseline to make an easy comparison among the biodiesels in respect of fuel properties, engine performance and emission characteristics. [Copyright &y& Elsevier]

Abstract: Essential sustainability requirements for biodiesel are that the product should be truly renewable and have a lower negative environmental impact than fossil fuels based on the latest insights. Biodiesel is not a most sustainable product in all geographical circumstances. This survey paper reviews the performance and prospects of rape biodiesel production on a global basis using some 40 life cycle assessments (LCAs). The paper identifies best (agricultural) practice and laggards. Life cycle energy balance depends on specific climatic conditions, and the agro- and processing technologies used. Alternative oilcrop cultivation practices and technologies were assessed. Opportunities to improve rape biodiesel life cycle energy efficiency and environmental impact by implementing new technologies in agriculture as well as in industrial processing have been identified for various Brassica oilcrop cultivars in relevant production areas. The consequences of large-scale renewable energy action plans have been considered. Improvements are needed for rape biodiesel to stay in business. The paper concludes with perspectives and recommendations. [Copyright &y& Elsevier]

Abstract: In recent years, biodiesel has attracted significant attention from researchers, governments, and industries as a renewable, biodegradable, and non-toxic fuel. However, several feedstocks have been proven impractical or infeasible because of their extremely high cost due to their usage primarily as food resources. Waste cooking oil (WCO) is considered the most promising biodiesel feedstock despite its drawbacks, such as its high free fatty acid (FFA) and water contents. This review paper provides a comprehensive overview of the pre-treatment and the usage of WCO for the production of biodiesel using several methods, different types of reactors, and various types and amounts of alcohol and catalysts. The most common process in the production of biodiesel is transesterification, and using a methanol–ethanol mixture will combine the advantages of both alcohols in biodiesel production. In addition, this paper highlights the purification and analysis of the produced biodiesel, operating parameters that highly affect the biodiesel yield, and several economic studies. This review suggests that WCO is a promising feedstock in biodiesel production. [Copyright &y& Elsevier]

Abstract: Energy is the most important necessity for human existence on the earth. Limited crude petroleum resources and increasing awareness regarding the environmental impacts of fossil fuels are driving the search for new energy sources and alternative fuels. Biodiesel is a fuel which is renewable, biodegradable, environmentally friendly, and non-toxic in nature and has attracted considerable attention during the past decades. The costs of feedstock and the production process are two major hurdles to large-scale biodiesel production in particular. Various technologies have been developed to reduce the production cost. This paper attempts to extensively review microwave-assisted technology for biodiesel production. Additionally, different types of feedstocks for biodiesel production have been summarized in this paper. It is concluded that the microwave-assisted technique reduces the reaction time significantly in comparison with conventional methods. In addition, a high quality biodiesel can be obtained from microwave-assisted transesterification of different kinds of oils. Finally, the energy payback for 1kg biodiesel produced by microwave-assisted technology is calculated in this paper and it indicated that the system is sustainable. Therefore it can be a suitable method of decreasing the cost of biodiesel and can also help the commercialization of this fuel. [Copyright &y& Elsevier]

Abstract: Because of biodegradability and nontoxicity biodiesel has become more attractive as alternative fuel. Biodiesel is produced mainly from vegetable oils by transesterification of triacylglycerols. From economic and social reasons, edible oils should be replaced by lower-cost and reliable feedstocks for biodiesel production such as non-edible plant oils. This paper reviews various methods for biodiesel production from common non-edible oils employing alcoholysis reactions. The aim of this paper is to present the possibilities of the use of non-edible oils into biodiesel production, to consider the various methods for treatment of non-edible oils and to emphasize the influence of the operating and reaction conditions on the process rate and the ester yield. The special attention is paid to the possibilities of optimization, kinetics and improvement of biodiesel production from non-edible oils. [Copyright &y& Elsevier]

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]

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]

Abstract: As the world confronts a reported food shortage and rising fuel prices, scientists around the globe are scrambling to develop biofuel feedstocks that would not divert food crops to energy. It is apparent that the demand for biodiesel is expected to increase in near future and although many edible oils might be the cheapest feedstock for biofuel production. But it may not be sustainable source to meet this increasing demand. This justifies the need to use non-edible oil seeds that can be the reliable sustainable feedstock for biofuel production. Furthermore, most of the non-edible seeds bearing trees have the potentials of reclaiming wasteland and does not compete with food crop for limited growing regions. It thus becomes imperative to search for dedicated non-edible feedstocks and their suitability for biodiesel production. This paper attempts to make an assessment of current energy scenario, potential of non-edible oil over edible oils, selected non-edible oil seeds as biodiesel feedstocks, impact of biofuel on environment and future direction. Experimental analysis by different researchers on these non-edible oils showed their great potential as feedstocks for biodiesel production. This paper also reviews the biology, distribution and chemistry of selected non-edible oil seeds plants. [Copyright &y& Elsevier]

Abstract: Biodiesel, derived from the transesterification of vegetable oils or animal fats, is composed of saturated and unsaturated long-chain fatty acid alkyl esters. In spite of having some application problems, recently it is being considered as one of the most promising alternative fuels in internal combustion engine. From scientific literatures, this paper has collected and analyzed the data on both advantages and disadvantages of biodiesel over conventional diesel. Since the aim of this study is to evaluate the biodiesel feasibility in automobiles, the first section is dedicated to materials compatibility in biodiesel as compared to that in diesel. The highest consensus is related to enhanced corrosion of automotive parts due to its compositional differences. In the subsequent sections, data on performance, emission and engine durability have been analyzed and compared. In this case, the highest consensus is found in reducing emissions as well as in increasing moving parts sticking, injector coking and filter plugging. This paper has also summarized the factors of biodiesel in contributing these technical performances. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a study based on the Systems Thinking and Scenario Planning (STSP) method, focusing the biodiesel production chain of Rio Grande do Sul State. The aim of the study was to identify key elements to comprehend the systemic structure of interaction among the ties of this chain. The study was held by a team of specialists over five months, including 15 meetings. Discussions were based on quantitative and qualitative data and a systemic map was constructed and refined. Based on this modeling, four different prospective scenarios were comparatively analyzed in order to propose strategic actions to promote the sustainability and competitiveness of the chain. The results were then presented to two different groups of external specialists in order to validate the conclusions drawn and the proposals. Both groups agreed with the ideas presented. The paper is constructed as follows: a brief introduction focusing on contextual elements of the biodiesel production in Brazil and in Rio Grande do Sul; some background material regarding agroindustrial production chains and an overview of the biodiesel production chain of interest; a description of the method used to perform the research; main results and discussion; and conclusions. With this paper the authors also hope to contribute to the discussion regarding competitiveness and sustainability of biofuel chains in Brazil. [Copyright &y& Elsevier]

Abstract: The increasing awareness of the depletion of fossil fuel resources and the environmental benefits of biodiesel fuel has made it more attractive in recent times. The cost of biodiesel, however, is the major hurdle to its commercialization in comparison to petroleum-based diesel fuel. The high cost is primarily due to the raw material, mostly neat vegetable oil. Used cooking oil is one of the economical sources for biodiesel production. However, the products formed during frying, can affect the transesterification reaction and the biodiesel properties. This paper attempts to review various technological methods of biodiesel production from used cooking oil. The analytical methods for high quality biodiesel fuel from used cooking oil like GC, TLC, HPLC, GPC and TGA have also been summarized in this paper. In addition, the specifications provided by different countries are presented. The fuel properties of biodiesel fuel from used cooking oil were also reviewed and compared with those of conventional diesel fuel. [Copyright &y& Elsevier]

The production of biodiesel through enzymatic routes has attracted significant attention, mainly because this can be regarded as a "green route" for the manufacture of fuels. In this way, an advanced bibliometric analysis comprising the global scientific production of biodiesel through immobilized enzymes was conducted. Thus, 923 papers were retrieved, analyzed, and classified according to the reported substrates, enzymes, supports, immobilization procedures, and reactors. Researchers from 748 institutions of 64 distinct countries authored the analyzed articles, showing the widespread interest in these technologies, although 10 countries concentrate more than 80% of the total number of documents published in this area, including China (23%), Brazil (17%), and India (11%). Particularly, most papers reported the use of vegetable oils (67%) as raw materials. In the last decade, approximately 80% of the published research focused on the use of supports to manufacture immobilized and insoluble biocatalysts. Enzymes have been obtained mostly from fungal sources (64%), especially lipases produced by Thermomyces lanuginosus (14.4%). Among the available commercial immobilized biocatalysts, Novozym 435 is certainly the one cited most frequently (55.9%) followed by Lipozyme RM IM (13.7%) and Lipozyme TL IM (16.7%). Additionally, the majority of the manuscripts reported the use of stirred tank reactors (83.0%) to perform the enzymatic reactions. Based on the surveyed literature, research trends indicate that new technologies are being developed to turn the enzymatic production of biodiesel more sustainable and economically viable, based mainly on the use of more active biocatalysts, more sustainable enzyme supports, and low-cost residues as raw materials. • Advanced bibliometric review about the production of biodiesel by immobilized enzyme was performed. • Chinese and Brazilian scientific communities are the most active in this field. • Novozymes 435 is the commercial biocatalyst used most often in this field. • Emerging technologies were identified for the synthesis of enzyme supports. • Sustainable supports and low-cost feedstocks are trends in the biodiesel production field. [ABSTRACT FROM AUTHOR]

Biodiesel is typically produced from a wide variety of edible vegetable oils. The cost of biofuels is projected to rise in the future as an alternative and ecologically suitable replacement to traditional fuel. Reliable and inexpensive raw materials, including meat processing by-products or waste animal fats, have rapidly attracted interest in biodiesel production. The operational and reaction parameters play an important role in the conversion of processes and biodiesel yield. Kinetic models explain the reaction rate and process optimization to improve the biodiesel conversion process. The process intensification approaches applied by different researchers are illustrated in the current study. This paper proposes a groundbreaking solution to stepping up biodiesel development by utilizing a coalescer reactor and a preliminary review to justify the solution's potential for further analysis. Optimization techniques and kinetics studies used to enhance biodiesel production from renewable sources are explored in the current review paper. • Biodiesel is projected to rise in the future as an alternative and ecologically suitable replacement to traditional fuel. • The effect of operational and reaction parameters on the conversion/yield of processes are reviewed. • To avoid these biodiesel development problems, the process intensification approaches applied by different researchers are also illustrated. • Method optimization, kinetics, and enhancing biodiesel output from renewable sources are explored in detail. [ABSTRACT FROM AUTHOR]

Transportation and shipping activities are major contributor to air pollution at sea where most of it occurs as a result of exhaust emissions from ships. Stringent emission limitations enforced by the International Maritime Organization have hastened the need to find a new alternative fuel for marine diesel engines. Thus, biodiesel fuel was chosen as one of the environmentally friendly alternative energy that can reduce ship toxic gas emissions and at the same time reduces dependence on petroleum-based fuels. Therefore, the purpose of this paper is to provide a comprehensive review of biodiesel as an alternative fuel for marine diesel engine applications. This review covers the biodiesel fuel background, engine performance, history, recent progress, engine warranty, issues, challenges, and possible solutions on using biodiesel for marine applications. A significant number of literatures from indexed journals were cited accordingly. The results of previous studies had shown that the use of biodiesel would mostly increase the amount of brake specific fuel consumption and nitrogen oxide gas while conversely reducing other toxic gas emissions. Although a number of issues and challenges arise, most marine engine manufacturers give conditional warranty against the use of biodiesel in the engines. The study concluded that biodiesel and its blends have a bright future in the marine sector, provided some of the highlighted issues can be solved. [ABSTRACT FROM AUTHOR]

Biodiesel is a renewable vehicle fuel based on biomass. Although environmental benefits can be assumed, both positive and negative impacts have been stated in the past, raising some doubts on the effective environmental performance of biofuels. They therefore need to be carefully examined through the established methods of Life Cycle Analysis (LCA). Such studies, though, have been known to give conflicting results and, for non-specialist users of environmental performance information, such variations in literature between studies will be a cause of concern. Following the principles of the ISO 14040 and 14044 standards for LCA, we have explored the variations in LCA methodology and parameter choices in a comparative analysis of 11 published studies of the production of biodiesel from palm oil. This study highlights inconsistencies between individual studies in aspects such as data coverage and completeness, system boundaries, and input and output streams. The importance of including factors such as plantation carbon sequestration and land use change demonstrates a need for consistent and appropriate methodologies. These factors are some of the most important drivers for variation in the results of LCA studies of palm oil systems, as well as being necessary for a comprehensive perspective. The results of this study also highlight the importance of geographical location and the fact that studies are often based on very limited data sources. A variance analysis identified the greatest source of variation across the chosen data sets, highlighting key methodology steps and pointed at pitfalls in employing supposedly environmentally benign technologies. The paper offers suggestions to i) assist inter-study comparisons, ii) offer non-LCA specialist users insight into the causes of variable results between LCA studies, and iii) guide further in-depth research. [ABSTRACT FROM AUTHOR]

Biodiesel is an attractive renewable energy in Iran. However, the concerns for food security, emissions, and water requirement move us towards developing the analytical framework to study emission-water nexus of biodiesel via the multi objective sustainable planning of biodiesel supply chain. Here, the literature of biodiesel in Iran is comprehensively reviewed and main issues are discussed. Then, a supply chain planning model is applied to depict the optimal path ways to minimize costs, net emission, and water use in Iran during 25 years. The microalgae via open ponds and jatropha cultivation reduce the total costs and improve negative emissions. The jatropha optimizes the water use and increases negative emissions. The results indicate that the integrated management of water must be carefully considered to select optimal pathway of the environmental friendly biofuel strategies. This paper provides the optimal frame work for the policy makers to consider different aspects for the future of the biodiesel supply chain of the country. [ABSTRACT FROM AUTHOR]

Biodiesel is gaining attention as a remedy for the increasing demand of fossil fuels which is depleting rapidly. Commercial homogeneous catalysts in the biodiesel production industry are facing challenges such as separation difficulties and severe corrosion which will lead to the increment of production and maintenance cost. Herein, this paper focuses on the comprehensive review of literature reported on the usage of biomass as the precursor for the catalyst used in biodiesel production. Compared to other commercial catalysts, the usage of biomass as catalyst precursor possesses several advantages such as abundantly available, cheaper raw materials, reusable, non-toxic and biodegradable. Carbon material synthesized from biomass which acts as the efficient support for active sites due to its high porosity and surface area characteristic has been studied widely. The latest development of biomass derived basic, acidic and magnetic heterogeneous catalyst through several state of the art synthesis pathways starting from the synthesis of the supporting material (carbon) until the functionalization process to form the complete catalyst was reviewed. Apart from direct sulfonation using sulfuric acid, sulfonation by reduction and arylation were less hazardous and provided comparable active sites activity. Most biomass based catalysts exhibited good catalytic performance by providing high biodiesel yield of above 80% at optimum conditions. Besides that, various kinetic models developed from the reaction kinetic study catalyzed by biomass based catalyst were also reviewed as a preparatory stage for the scaled-up commercialization process of the studied catalyst in the biodiesel production sector. This catalyst could assist to lower the activation energy required for the reactions and thus enables higher reaction rate to reach equilibrium. Continuous research on producing high performing biomass based catalyst with minimum resources is needed in order to achieve the ultimate goal of green and sustainable biodiesel industry. [ABSTRACT FROM AUTHOR]

The dwindling of natural resources such as crude oil, coal etc. has made it essential to switch over to biodiesel. Biodiesel has a number of properties which are beneficial to the environment. The main advantage of biodiesel is that it's carbon neutral and it does not create carbon dioxide (CO 2 ). In addition, it leads to a decrease in pollution by reducing the emission of harmful and hazardous substances to the atmosphere and greatly improves the engine performance. This paper puts forward a comprehensive assessment of biodiesel production from various non-edible oils such as waste fried oil, pyrolysis oil, preheated palm oil, waste cooking oil, jatropha oil, karanja oil etc. It also serves as an index to measure combustion, performance and emission characteristics in a variable compression ratio (VCR) diesel engine, where biodiesel is blended with diesel. The need for switching over to VCR engine is that it provides better fuel efficiency, up to 30% reduction in fuel consumption, better control at peak cylinder pressure, ability to use multi-fuel and reduction in the exhaust emissions when compared to that of a constant compression ratio diesel engine. [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]

In recent years, biodiesel production has grabbed significant attention due to the awareness of fossil fuel exhaustion. Microalgae become interested feedstock candidate of biodiesel production as they have rapid growth rate and high oil content compared to crops. Efforts have been made to increase microalgae productivity and oil content. To investigate the potential of microalgae for biodiesel production, it is essential to knowledge if the microalgae oil is qualified as possible feedstock oil. Moreover, what would be the energy and environmental effect of the production? And whether the production cost would be reasonable? This paper compared the properties of microalgae oil with traditional biodiesel production oils (vegetable oils); the properties of the biodiesel produced from microalgae and vegetable oils; reviewed the net energy ratio (energy output to energy input), GHG emissions, and economic analysis of the process of biodiesel production from microalgae; as well as discussed the factors which would influent the energy, environment, and cost of the process. [ABSTRACT FROM AUTHOR]

In this paper, a detailed review on the recent advances in the production of biofuels and biochemicals from microalgae and Jatropha is presented. This review includes critical elements of the sustainability of microalgae and Jatropha biorefineries such as technical analysis, socioeconomic considerations, and environmental impact assessments that are reported in recent studies. The integration of microalgae and Jatropha as viable feedstock for the production of biofuels and biochemicals which may serve as sustainable alternatives to fossils fuels and petrochemicals is also modeled using SuperPro designer. A technoeconomic assessment of the integrated biorefinery is carried out. United Arab Emirates (UAE) is considered as a geographical reference for the technoeconomic assessment. Three scenarios are examined. All scenarios involve the production of biodiesel and glycerol. In addition to these two products, the production of animal feed, organic fertilizer and biogas is considered in scenario 1. In scenario 2, the biorefinery products include bioethanol, organic fertilizer and biogas. Scenario 3 involves the production of hydrogen and animal feed. Scenario 1 is the base case, with which other scenarios are compared. Scenario 1 is profitable but scenarios 2 and 3 are not profitable. In addition, emissions from scenario 2 make it less attractive when it is compared to other scenarios. The integrated biorefinery with microalgae and Jatropha as feedstock is technically feasible and economically profitable in scenario 1, as modeled. [ABSTRACT FROM AUTHOR]

In the effect of robust industrialization and rapid augmentation of a number of fleets, there has been a huge rise in the fossil fuel consumption. Tremendous increase in global warming threatens the ecological balance of the earth. Based on the recent sorts of hardship about the fuel, researchers are profoundly pondered over the field of renewability, environmentally friendly and economically doable. In recent decades biodiesel fuel becomes the center of attraction among researchers since it is renewable, bio degradable, non-noxious, eco-friendly and sustainable. This review paper highlights and reviews the properties of prosperous variety of the biodiesel fuels derived from non-edible feedstocks which are termed as third generation biodiesel and its effects on the performance and emissions of the diesel engines. It was observed that the physicochemical properties of the biodiesel differ based on the types of feedstocks and also have a considerable effect on the potential performance of engine and dynamic characteristics of emission level. Also, the usage of biodiesel commonly leads to a reduction in noxious pollutants like carbon monoxide, unburnt hydrocarbon and particulate matter with an obvious increase in fuel consumption and NOx emission. This review provides a prospective strategy for the researchers for enhancing the engine performance and emission characteristics by using the third generation biofuels and its blends with the productive marvelous outcomes. [ABSTRACT FROM AUTHOR]

Today in every nation's agenda, the utmost priority is given to reduce the impact of pollution (emissions related to air and water) that is created through different sources. This pollution is highly impacting our life on the daily basis. The best way is to reduce the pollution by encouraging usage of environment friendly activities. Moreover, the rate by which our conventional (non-renewable) sources of fuel depleting is really alarming and might perish in long run. The only way for the sustainable development is by adopting eco-friendly and renewable sources of fuel. Oxygenated fuel is an alternative fuel for the diesel engine because it is reversible in nature and its emissions are low. This paper has focused on the impact of different modification made in CI (compression ignition) engines in order to work at their optimum level in terms of combustion, emission and performance. The modification in engine had carried out by varying injection pressure (IP), injection timing (IT),compression ratio (CR), combustion chamber geometry etc. Results show that at high value of CR, IP and retardation or advancement of IT shows the improvement in the combustion, performance and emissions characteristics of CI engines. At modified conditions brake specific fuel consumption, unburned hydrocarbon, smoke opacity and carbon monoxide emission decreases and brake thermal efficiency and nitrogen oxide emission increases as compared to without modified ones. The result also shows that retarded injection timing as compared to original injection timing, emission of nitrogen oxide decreases. [ABSTRACT FROM AUTHOR]

This paper discusses about the importance of animal fats for power generation particularly from waste chicken fat, advantages of using chicken fat for biodiesel production, different ways of oil extraction from chicken fat and various biodiesel production techniques. A detailed review has been done on the use of novel heterogeneous catalysts for transesterification process such as metal based catalysts and organic catalysts. The factors influencing transesterification parameters like molar ratio, catalyst weight percentage, reaction time and temperature has been collected from several research articles were presented in detail. In addition, the transesterification reaction is studied at different co solvents employed to increase the methyl ester conversion. Also, analyses of relative optimization techniques implementing for transesterification process parameters have been discussed thoroughly. The physico-chemical properties of chicken fat methyl ester such as kinematic viscosity, density, pour, cloud, flash and cold filter plugging point, calorific value and fatty acid compositions of chicken fat methyl ester were compared with different animal fat methyl esters. The study reveals that biodiesel produced from waste chicken fat would be a suitable replacement of edible vegetable oils due to its low cost, ease of availability and the properties of chicken fat methyl ester were within the limits of ASTM D 6751 biodiesel standards. Furthermore, the research work has to be carried out for the improvement of cycles of catalyst reusability, biodiesel purity and cost-effectiveness of biodiesel production process in future. [ABSTRACT FROM AUTHOR]

In the rapidly growing global energy consumption, diesel engines play the key role. Usage of diesel fuel contributes to harmful air pollution exhausted from combustion chamber. To overcome these serious issues, the biodiesel extracted from many feedstocks have been studied and implemented for the past few decades. The combustion characteristics of diesel are not same as the biodiesel blends due to the discrepancy in physio-chemical properties of biodiesel. Enormous studies have been focused on inadequate combustion profiles of biodiesel in compression ignition engines. This review paper analyzes the previous researches concerning the consequences of proposed effective strategies including the variation in engine operating parameters like fuel injection timing and injection pressure for enhancing combustion characteristics of biodiesel implementation. This study focuses its light on the advancement and retardation methods of injection timing and injection pressure to treat the engine combustion indicators such as in-cylinder pressure, peak cylinder pressure, heat release rate, ignition delay period and combustion duration, finally a comparative evaluation has been developed and the relevant reasons for the variation of combustion characteristics have been conversed. The review concludes that the advancement in injection timing and higher injection pressure are best in amplifying the combustion phenomena of biodiesel fuelling. [ABSTRACT FROM AUTHOR]

This paper summarizes the biodiesel production capacities and the indigenous oil-based feedstock potential of Serbia for the first time. The current demands and future trends in diesel fuel consumption in Serbia are presented in order to estimate the biodiesel perspectives. The comprehensive review explores the potentials of the available conventional biodiesel sources (oilseed crops), as well as the next generation biodiesel sources, including waste cooking oil and oil from non-edible agro-food wastes that were previously reported as potential biodiesel feedstock in Europe. Results suggest that the Serbian agriculture can provide oilseed crops for the production of 128,000–266,000 t of biodiesel annually in addition to the quantities of oilseed crops required by the domestic food and fodder industries. Nevertheless, selecting edible vegetable oils as a potential feedstock for biodiesel cannot be considered as a long-term choice due to the associated “food versus fuel” debate. Thus, exploring the non-edible waste feedstock is important. Around 10,000 t of biodiesel could be produced from the collectable waste cooking oil. Other potential alternative oil resources indigenous for Serbia, such as tomato, grape and tobacco seeds, can provide raw material for the production of further ca. 8,000 t of biodiesel annually. Lack of governmental incentives and higher profitability of the edible oil sector have caused that the installed capacities for biodiesel production (ca. 126,000 t annually) are largely out of operation since 2008. Nevertheless, the results suggest that with the introduction of appropriate measures there is a realistic basis to fulfil the goals set by the National Renewable Energy Action Plan which requires that the annual biodiesel production from domestic sources should reach 98,000 t by 2020 in Serbia. [ABSTRACT FROM AUTHOR]

Biodiesel is an alternative, renewable, biodegradable and environmentally friendly fuel for transportation, with properties like petroleum-derived diesel, and can be used directly in a compression ignition engine without any modifications. The world's fossil fuel and crude oil reserves are going to dry up in the next few decades, but, contrariwise, an attractive, high quality, readily available and economically extractable oil from microalgae is a substitute feedstock to produce alternative biodiesel fuel for the transportation sector in the future. Microalgae have a higher biomass productivity (tons/hectare/year) and lipid yield (kg/kg of algal biomass) as compared to vegetable oil crops. To overcome the problem of energy deficiency in developing countries, like Pakistan, and boost their economic growth, alternative fuels are proving very important for environment-friendly and sustainable development, especially in the last few decades. Different research studies on microalgae cultivation, characterization of microalgae oil (lipids), and evaluations of its socio-economic feasibility to produce renewable biodiesel have been conducted in the past in Pakistan for its future prospects. This review paper includes the overall summary and compilation of the microalgae research conducted in Pakistan on biodiesel production and includes the algal biodiesel production cost analysis. The studies showed promising results for harnessing microalgae and using its lipids to produce biodiesel with favourable properties that were comparable to the conventional diesel in Pakistan. The information related to the microalgae research will help stakeholders and governmental organisations working in the renewable energy sector to consider its cultivation on a large scale, using waste water as a feedstock to produce biodiesel to meet the target set by the Government of Pakistan of using 10% blended biodiesel by the year 2025 in Pakistan. [ABSTRACT FROM AUTHOR]

The suspended microalgal cultivation systems targeting the production of lipid for biodiesel is still unable to meet the commercial and economic feasibility due to high energy and cost inputs during the harvesting process. Currently, the attached microalgal cultivation systems are known as an innovative technology to resolve the problematic aspects of suspended cultivation as the biomass can be easily separated from the culture medium with negligible energy input and no chemical need. Accordingly, this paper is focusing on reviewing various support materials utilized by researchers in growing the attached microalgal biomass in either fixed bed or fluidized bed bioreactor to ensure sustainable biomass production prior for biodiesel. An extensive review of the cultivation conditions impacting the growth of attached microalgal biomass is conducted in determining the optimized condition to enhance biomass productivity. The novelty of this paper is presented through in-depth analyses and discussions concerning the kinetic models and mechanisms study in selecting the suitable support materials for attached microalgal growth system. The incorporation of the cultivation condition parameter in predicting the growth of attached microalgae biomass via kinetic study is crucial in proffering new directions for technological developments and microalgal industry application. The ability of attached microalgal biomass in efficiently assimilate the nutrients available in the nutrient-rich wastewater for the microalgae growth is considered as an economical feasible approached. The suitable photobioreactor designs for growing the attached microalgal biomass are also discussed in detail in ensuring the sustainability of attached microalgal biomass production. Image 1 • Attached cultivation to ease microalgal biomass harvest for biodiesel production. • Microalgae cells attachment mechanism onto the support material. • Kinetic model to predict the growth of attached microalgal biomass. • Nutrient-rich wastewater treatment via assimilation by attached microalgal biomass. • Type of photobioreactors to promote the growth of attached microalgal biomass. [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]