ARS | Publication request: NEW USES FOR REFINERY BYPRODUCTS: BIODIESEL FROM SOYBEAN SOAPSTOCK

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 4, 2003
Publication Date: March 1, 2004
Citation: Haas, M.J., Scott, K.M., McAloon, A.J., Foglia, T.A. 2004. New uses for refinery byproducts: biodiesel from soybean soapstock [abstract]. Proceedings IV International Soybean Processing and Utilization Congress. p. 994-999.

Technical Abstract: Semi-refined and refined vegetable oils are the predominant feedstocks for the production of biodiesel. However, their relatively high cost renders the resulting fuels unable to compete economically with petroleum-derived fuel. We have investigated the production of fatty acid methyl esters from soapstock, a byproduct of edible oil refining that is substantially less expensive than edible grade refined oils. The most effective method involved the complete saponification of the soapstock, followed by acidulation using methods similar to those presently employed in industry. This resulted in an acid oil with a free fatty acid content greater than 90%. These fatty acids were efficiently converted to methyl esters by acid-catalyzed esterification, resulting in a product that met the accepted US specifications for biodiesel. Engine emissions and performance during operation on soy soapstock biodiesel were comparable to those on biodiesel produced from soy oil. An economic analysis suggested that the production cost of soapstock biodiesel would be approximately US$ 1.54/gal. This is 25% lower than the estimated cost to produce biodiesel from soy oil.