Scope of biodiesel from oils of woody plants: a review

Non-edible oils obtained from chosen non-conventional woody plants are considered as potential raw materials for biodiesel production. These plants mostly grow in wastelands. Structural characteristics of these oils as raw material are very much in tune with the properties of biodiesel such as long-chain hydrocarbon, having an adequate level of unsaturation with branched chain. Four primary methods are being followed to make biodiesel from vegetable oil. They are direct use through blending, microemulsion, thermal cracking (pyrolysis) and transesterification. Non-edible oil would eliminate the issue of food vs fuel. The biodiesel manufactured from oils of woody plants may partially reduce the demand for liquid-fuel energy and addresses the environmental consequences of using fossil fuels. Oil from a total of 17 species of woody plants (Angiosperms) belonging to 14 families are considered in this paper. The habit, habitat and geographical distribution of each species are also presented. The physico-chemical properties of their oil, with special reference to the fatty-acid profile that ultimately decides the characteristics of the biodiesel prepared from them, are reviewed.