Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/31/2011
Publication Date: 10/1/2011
Citation: Haas, M.J., Wagner, K. 2011. Simplifying biodiesel production: the direct or 'in situ' transesterification of algal biomass. European Journal of Lipid Science and Technology. 113,No. 10, p.1219-1229. Interpretive Summary: Economic competitiveness is vital to the adoption of biofuels in place of petroleum fuels, and will also be crucial to the desired removal of subsidies to support these new technologies. High feedstock costs and process costs can render biodiesel economically uncompetitive when produced by contemporary technologies. The goal of this research was to investigate a new alternate means of producing biodiesel. It is a simpler process than used in current industrial methods, and may offer an opportunity to reduce biodiesel production costs. Moreover, this new method, termed ‘in situ’ transesterification, is investigated here as a method for biodiesel production from algae. With high lipid levels, the ability to be grown on non-agricultural lands, and the fact that algae are not used as a food source, these organisms are of great interest as future feedstocks for biofuel production. The work described here investigates and optimizes the conditions for maximum production of the components of biodiesel by in situ transesterification of this new biofuel feedstock.
Technical Abstract: The ‘in situ’ esterification/transesterification of algal biomass lipids to produce fatty acid methyl esters (FAME), for potential use as biodiesel, was investigated. Commercial algal biomass was employed, containing 20.9 wt percent hexane extractable oil. This consisted of 35.1 wt percent free fatty acids (FFA), 18.2 wt percent triacylglycerols (TAG), and 9.8wt percent monoacylglycerols (MAG). The predominant fatty acids in the oil were palmitic (42.4 wt percent), oleic (30.6 wt percent), linoleic (22.8 wt percent), and linolenic (16.1 wt percent). Small amounts of 10-keto 16:0 and 10-OH 16:0 fatty acids were also present. Statistical experimental design was employed to coordinately examine the effects of the amounts of methanol, sulfuric acid and reaction temperature (23 - 65 degrees C) on the yield of FAME in 2 h reactions. Three methods of feedstock preparation were examined - as received, oven dried, and water- washed/dried. For all feedstocks, conditions could be identified which were predicted to yield greater than 90 percent maximum theoretical FAME production. Oven drying the feedstock reduced the amount of methanol required, with 83 percent of maximum yield obtained at a methanol/fatty acid molar ratio of 220:1 (4 mL methanol/g substrate). Water washing the biomass did not reduce the methanol required for high level transesterification.