(63x) Optimizing Pilot Plant Biodiesel Production

Conventional biodiesel is a fuel made by converting triglycerides in oils and fats to methyl esters. To improve campus sustainability, Hope College is implementing a small scale pilot plant to convert waste vegetable oil (WVO) from the dining halls to biodiesel. This research investigated alternative raw materials, processing steps, and operating conditions for the pilot plant. Substitution of ethanol for methanol resulted in successful conversion of WVO to ethyl esters; however, conversions varied from 80.0 to 88.1 percent compared to 91.8 to 94.6 percent for methyl ester biodiesel. Furthermore, the raw material cost of ethanol was 45 percent higher than methanol per gallon of biodiesel product. Molar ratios of 5:1 and 6:1 methanol to oil resulted in costs per gallon of biodiesel between $1.61 and $1.80. Using a 4:1 ratio produced a high viscosity waste stream that limited practical implementation. Partial recycling of the waste obtained from the production of biodiesel enabled approximately 51% of the initial alcohol and 88% of the initial catalyst to be reused, decreasing cost per gallon by $0.52. This process was proved to be a feasible option for the college.