Techno-Economic Assessment of Different Pathways for Utilizing Glycerol Derived From Waste Cooking Oil-Based Biodiesel

Crude (i.e., unrefined) glycerol is the major by-product of biodiesel production, based on the homogeneous alkaline catalytic transesterification reaction. Currently, global biodiesel production capacity has been rising rapidly due to the overall growth of renewable energy demand. The amount of glycerol is increasing in parallel, and there is presently little market value for crude glycerol. In addition, disposing of this material via conventional methods becomes one of the major environmental issues and a burden for biodiesel manufacturers. Thus, utilization of purified glycerol in value-added applications such as food processing, cosmetics, soap and pharmaceuticals is critical to achieve economic scale of biodiesel production. In this paper, various pathways available to community-based biodiesel producers have been modeled to inform the decision-making process. A case study at Rochester Institute of Technology (RIT) was selected to evaluate the proposed system. Different pathways of utilizing crude glycerol were investigated, and economic feasibility of each pathway was analyzed. Purification of crude glycerol from waste cooking oil-based-biodiesel production was performed at small bench scale. Various recipes with different raw materials and purified glycerol as an ingredient were created for different kinds of saponification processes and applications. The resulting data from this preliminary assessment showed that producing biodiesel and high-quality soap is the most profitable option for RIT.