In recent decades, the concern over depletion of the world׳s petroleum reserves and environmental pollution has increased the demand to develop a renewable and environmental friendly fuel. Biodiesel, which mainly consists of Fatty Acid Methyl Esters (FAME) is one of the best substitutes for diesel fuel. Currently, vegetable oils, edible or non-edible, are the main resources of biodiesel. This review aims at providing comprehensive information and analyzes on biodiesel produced from edible and non-edible vegetable oils, their composition and specifications. Accordingly, the Fatty Acid (FA) profiles of 28 edible vegetable oils and 40 non-edible vegetable oils were collected. Their main specifications including sulfur content, density, viscosity, flash point, cloud point, pour point, cold filter plugging point, cetane number, iodine number, heating value, acid value and carbon residual before and after transesterification (vegetable oil and biodiesel, respectively) were analyzed in detail. Many researchers have developed prediction models to quantify biodiesel specifications to optimize its manufacturing and obtain biodiesel with the best specifications. Three factors that are especially influential are the fatty acids profiles, the degree of unsaturation within the FA structures and molecular weight. Accordingly, many models have been constructed on these features. There are also models that quantify the relationship between the biodiesel specifications and its thermodynamic properties or other specifications. Accordingly, the second part of this work was conducted on the existing prediction models. All the models were discussed along with their deviation in prediction.

A comprehensive review on properties of edible and non-edible vegetable oil-based biodiesel: Composition, specifications and prediction models

NOx emission of biodiesel compared to diesel: Higher or lower?

Solid state fermentation of food waste mixtures for single cell protein, aroma volatiles and fat production.

Seeds recovered from industry by-products of nine fruit species with a high potential utility as a source of unconventional oil for biodiesel and cosmetic and pharmaceutical sectors.

Cell genetics, culture conditions and the recovery efficiency of cells and products are the bottlenecks for industrial bioprocesses from microalgae. Microalgae lipids can be used for different applications, e.g., drugs, food, and biofuels, and their purpose considers the nature and concentration of the lipids that are wished to obtain. For the biotechnological production of lipids, adequate culture conditions are necessary to enable the cell strain to obtain high biomass and lipid yields and productivities. Also, the processes of separating the cells from the culture medium and releasing the lipids from that biomass need to be efficient and economically viable. Considering that cultivation, cell recovery and lipid extraction directly reflect the results obtained, the most appropriate methods for these operations must be applied. Many literature reviews report the lipid and fatty acid contents obtained through the cultivation of different microalgae species and strains. However, few studies relate the contents of these biomolecules, either with the methods of obtaining the biomass or with the extraction of lipids. Even so far there is no review in the literature with such an approach. The aim of this work was to review and discuss the culture conditions for different microalgae strains and their influence on lipid content; the separation of microalgae biomass, including biomass thickening methods, and methods of biomass depletion; the methods of cellular disruption and lipid extraction; the influence on biofuels’ production, e.g. biodiesel, bioalcohols and biohydrogen; and the influence of green chemistry (solvents and extraction technologies) for a sustainable production of biofuels under the concept of biorefinery.

Hai-yan Yu

Papers

Influence of fatty acid composition of woody biodiesel plants on the fuel properties