Biodiesel production has the potential to both reduce foreign dependence and environmental damage (Agnew et al. 2007). It is non-toxic, biodegradable, and has lower emissions of carbon monoxide, particulate matter, and unburned hydrocarbons as compared to petroleum-based fuels. It also has health benefits because biodiesel has no sulfur or carcinogenic components. Despite the environmental and health-related advantages, biodiesel from fresh oil is not economical in the short-term. Raw materials alone account for approximately 70–95% of total manufacturing costs. Thus, studies are being conducted to evaluate the feasibility of converting used cooking oil into biodiesel.— Alec Faggen
Agnew, R., Ming, C., Lu, M., 2009. Making Biodiesel from Recycled Cooking Oil Generatd in Campus Dining Facilities. Mary Ann Liebert, Inc 2, 303–307.
Agnew and colleagues working in the Department of Civil and Environmental Engineering of the University of Cincinatti participated in one such study using a transesterification methodology to convert methanol and fryer oil from campus dining halls into biodiesel (or methyl esters) and glycerol. They began by using an acid-base titration in order to determine the amount of catalyst (sodium hydroxide) needed for their oil supply and discovered a higher content of free fatty acids compared to the majority of waste oils described in the literature, a result of the hydrolysis of triglycerides during heating. Later, they varied the catalyst in small-scale pilot tests to determine optimal catalyst usage for each batch of recycled oil. Recycled oil requires more catalyst and higher gelling temperatures than fresh oil because frying produces free fatty acids. Filtration is also necessary to remove any remaining food debris. The catalyst (NaOH) is dissolved into the methanol and mixed for over an hour with heated cooking oil. After settling for eight hours, the glycerin’s higher density separates it from the biodiesel, so the glycerin is drained from the bottom of the reactor. After multiple washings with water to remove the catalyst and a final filtration using hairnets, the biodiesel is ready for use in a diesel engine.
Since the start of the project in 2007, the University of Cincinnati has produced hundreds of gallons of biodiesel. The fuel has been successfully tested in a Jeep’s diesel engine, and it is in the process of being used by both delivery fleets and shuttle services. The university has also signed an agreement to use 2% biodiesel in its utility plant plants, providing an example to both its own community and other universities by demonstrating the viability of a more environmental and economical means for energy production.