Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/1/2005
Publication Date: 7/30/2005
Citation: Knothe, G.H., Dunn, R.O. 2005. Biodiesel: an alternative diesel fuel from vegetable oils or animal fats. In: Erhan, S.Z., editor. Industrial Uses of Vegetable Oils. Chapter 4. Champaign, IL: AOCS Press. p. 42-89.
Technical Abstract: Biodiesel is defined as “a fuel comprised of the mono-alkyl ester of long chain fatty acids derived from vegetable oils or animal fats." Accordingly, biodiesel is derived from vegetable oils or animal fats by a transesterification reaction, in which the oil or fat is reacted with a monohydric alcohol in the presence of a catalyst. Methanol is the alcohol used most commonly to produce biodiesel as it is the least expensive alcohol in many countries. Besides transesterification to alkyl esters, three other approaches - dilution with conventional, petroleum-based diesel fuel, microemulsions (co-solvent blending), and pyrolysis - have been explored for utilizing vegetable oils as fuel. However, as the mono-alkyl esters of vegetable oils and animal fats - biodiesel - are the only approach that has found widespread use (and, accordingly, the vast majority of research papers deal with this approach), this article will focus on such mono-alkyl esters.