As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available resources that have come to the forefront recently. In this paper, a detailed review has been conducted to highlight different related aspects to biodiesel industry. These aspects include, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodiesel, the economical viability and finally the future of biodiesel. The literature reviewed was selective and critical. Highly rated journals in scientific indexes were the preferred choice, although other non-indexed publications, such as Scientific Research and Essays or some internal reports from highly reputed organizations such as International Energy Agency (IEA), Energy Information Administration (EIA) and British Petroleum (BP) have also been cited. Based on the overview presented, it is clear that the search for beneficial biodiesel sources should focus on feedstocks that do not compete with food crops, do not lead to land-clearing and provide greenhouse-gas reductions. These feedstocks include non-edible oils such as Jatropha curcas and Calophyllum inophyllum , and more recently microalgae and genetically engineered plants such as poplar and switchgrass have emerged to be very promising feedstocks for biodiesel production. It has been found that feedstock alone represents more than 75% of the overall biodiesel production cost. Therefore, selecting the best feedstock is vital to ensure low production cost. It has also been found that the continuity in transesterification process is another choice to minimize the production cost. Biodiesel is currently not economically feasible, and more research and technological development are needed. Thus supporting policies are important to promote biodiesel research and make their prices competitive with other conventional sources of energy. Currently, biodiesel can be more effective if used as a complement to other energy sources.

A comprehensive review on biodiesel as an alternative energy resource and its characteristics

World energy demand is expected to increase due to the expanding urbanization, better living standards and increasing population. At a time when society is becoming increasingly aware of the declining reserves of fossil fuels beside the environmental concerns, it has become apparent that biodiesel is destined to make a substantial contribution to the future energy demands of the domestic and industrial economies. There are different potential feedstocks for biodiesel production. Non-edible vegetable oils which are known as the second generation feedstocks can be considered as promising substitutions for traditional edible food crops for the production of biodiesel. The use of non-edible plant oils is very significant because of the tremendous demand for edible oils as food source. Moreover, edible oils’ feedstock costs are far expensive to be used as fuel. Therefore, production of biodiesel from non-edible oils is an effective way to overcome all the associated problems with edible oils. However, the potential of converting non-edible oil into biodiesel must be well examined. This is because physical and chemical properties of biodiesel produced from any feedstock must comply with the limits of ASTM and DIN EN specifications for biodiesel fuels. This paper introduces non-edible vegetable oils to be used as biodiesel feedstocks. Several aspects related to these feedstocks have been reviewed from various recent publications. These aspects include overview of non-edible oil resources, advantages of non-edible oils, problems in exploitation of non-edible oils, fatty acid composition profiles (FAC) of various non-edible oils, oil extraction techniques, technologies of biodiesel production from non-edible oils, biodiesel standards and characterization, properties and characteristic of non-edible biodiesel and engine performance and emission production. As a conclusion, it has been found that there is a huge chance to produce biodiesel from non-edible oil sources and therefore it can boost the future production of biodiesel.

Non-edible vegetable oils: A critical evaluation of oil extraction, fatty acid compositions, biodiesel production, characteristics, engine performance and emissions production

Production and comparison of fuel properties, engine performance, and emission characteristics of biodiesel from various non-edible vegetable oils: A review

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.

Biodiesel production from non-edible plant oils

Production of biodiesel from high-FFA neem oil and its performance, emission and combustion characterization in a single cylinder DICI engine

The present work aimed at the standardization of transesterification process parameters for the production of methyl ester of filtered neem oil and fuel characterization for engine performance. The effect of process parameters such as molar ratio, preheating temperature, catalyst concentration and reaction time was studied to standardize the transesterification process for estimating the highest recovery of ester with lowest possible viscosity. Based on the observations of the ester recovery and kinematic viscosity, it was found that filtered neem oil at 6:1 M ratio (methanol to oil) preheated at 55 °C temperature and maintaining 60 °C reaction temperature for 60 min in the presence of 2 percent KOH and then allowed to settle for 24 h in order to get lowest kinematic viscosity (2.7 cSt) with ester recovery (83.36%). Different fuel properties of the neem methyl ester and neem oil were also measured. Results show that the methyl ester of neem obtained under the optimum condition is an excellent substitute for fossil fuels.

Optimization of neem methyl ester from transesterification process and fuel characterization as a diesel substitute

https://link.springer.com/content/pdf/10.1007%2Fs12182-017-0183-0.pdf

Optimization of safflower oil transesterification using the Taguchi approach

Neem oil methyl ester (NOME) was tested in 4-stroke single cylinder water cooled diesel engine. Brake thermal efficiency of NO100 has been found 63.11 % higher than that of diesel at part load whereas it reduces 11.2% with diesel fuel at full load. As NOME is concerned, HC is reduced at all load condition, whereas smoke is also reduced at full load condition. NOx has reduced slightly at all load condition, and EGT showed increasing trend at full load condition. Other emissions (CO,CO 2 and O 2 ) do not contribute bad effect on engine. Thus, NOME can be a substitute for diesel fuel in diesel engine.

http://nopr.niscair.res.in/bitstream/123456789/7045/1/JSIR%2069%281%29%2062-66.pdf

Performance and emission evaluation of a diesel engine fueled with methyl ester of neem oil and filtered neem oil

The present study was conducted to standardize the esterification process parameters for the production of methyl ester of raw hemp oil. The effect of process parameters such as molar ratio, catalyst concentration, and reaction time was studied to standardize the esterification process and for estimating the highest recovery of ester with lowest possible viscosity. Based on the observations from the ester recovery and kinematic viscosity, it can be seen that raw hemp oil at 6:1 M ratio may be reacted with methanol at 60 °C reaction temperature for 45 min in the presence of 2 g of KOH and then allowed to settle for 24 h in order to get lowest kinematic viscosity with ester recovery of 90.62%. The yield of hemp methyl ester was found to be 90.62% with oil methanol ratio of 0.37 w/w and 0.01 w/w alkali catalyst. Different fuel properties such as density, kinematic viscosity, flash point, fire point, cloud point, pour point, free fatty acid content and calorific value of the hemp methyl ester and hemp oil were measured. From the properties and engine test results it has been established that methyl ester of hemp oil can be substituted for diesel oil. Methyl ester of above non-edible oil has several advantages among other new renewable and engine fuel alternatives along with its environmental benefits.

Brown hemp methyl ester: Transesterification process and evaluation of fuel properties

The physicochemical properties of biodiesel are very similar to those of petroleum diesel fuel. The main focus of this study is the production of the biodiesel from grape seed oil. This study shows...

S. S. Ragit

Papers

Optimization of neem methyl ester from transesterification process and fuel characterization as a diesel substitute

Optimization of safflower oil transesterification using the Taguchi approach

Performance and emission evaluation of a diesel engine fueled with methyl ester of neem oil and filtered neem oil

Brown hemp methyl ester: Transesterification process and evaluation of fuel properties

Optimization of biodiesel production from grape seed oil using Taguchi's orthogonal array