An enviro-economic assessment of waste vegetable oil to biodiesel conversion : an analysis of cost and GHG emissions for the University of Texas at Austin

With its multiple dining halls, close proximity to restaurants, and diesel vehicle fleet, the University of Texas at Austin (UT) has both the supply of raw materials to implement a waste vegetable oil to biodiesel recycling program and the capacity to use it. At face value, implementing a large-scale recycling program provides a source of cheap, low emissions fuel. However, the feasibility of such a program is contingent on its economic cost and environmental impact relative to alternative fuel sources. Thus, this research estimated the greenhouse gas (GHG) inventories and the unit cost associated with 1 megajoule worth of recycled biodiesel derived from three production processes –Alkali Catalyzed, Acid Catalyzed, and Supercritical Methanol–using environmental life cycle assessment and life cycle costing. These GHG inventories and unit costs were then compared to the conventional diesel and oilseed biodiesel sources that make up UT’s current fuel portfolio. This analysis suggested that implementing a recycling program using a Supercritical Methanol biodiesel conversion process would have the lowest combined GHG impact and unit cost, although as an emerging technology, it poses a high investment risk. In general, these findings are encouraging to the success and impact of a large-scale recycling program.