The simple science of biodiesel production

Biodiesel is one of the big players in affordable, accessible, and safe renewable alternative fuels.  It is produced by converting animal or plant oils into a diesel fuel that can be used in internal combustion engines like automobiles or electric generators.  Most biodiesel is produced on an industrial scale.  In 2012, the biodiesel industry produced nearly 1.1 billion gallons of biodiesel, more than any other type of advanced biofuel designated by the EPA.  However, as we proved in our class’s lab, making biodiesel is not limited to large-scale production.  The procedure is relatively simple and can be performed by individuals to fuel their own vehicles.

To produce biodiesel, first an oil source must be chosen.  In our lab, we used discarded oil from USD’s dining services, bacon grease, Crisco, and several types of plant-derived oils.  These oils exist mostly in the form of triglycerides, which are made up of a glycerol molecule bound to three fatty acids.  To convert these triglycerides to biodiesel, the fatty acids must be removed from the glycerol.  To do this, oil was reacted with methanol in a basic solution in order to perform a “transesterification” whereby each fatty acid’s bond to glycerol is replaced by a methyl group.  One of the main contaminants in biodiesel is water, so in our experiment, a great deal of time was spent heating the biodiesel to evaporate leftover water.  Additional tests were performed to determine the toxicity level of the fuel, the heat of combustion, and the chemical makeup using GC-MS.

I was shocked by how simple this process was, and was curious to find out why more vehicles don’t run on biodiesel.  One of the major barriers to widespread application is vehicle engine makeup.  In order to use fuel containing high biodiesel content in a regular diesel vehicle, modifications must be made to engine components to prevent degradation.  Some vehicles can use diesel fuels containing up to 20% biodiesel (called B20) without being modified, and lower biofuel mixes are often available such as B5 or B2.  The U.S. is lagging behind Europe in terms of biofuel adoption.  Europe accounts for about 85% of worldwide biodiesel production, and 100% biodiesel (B100) is available at many fuel stations.  Modern diesel vehicles are becoming popular for their fuel economy and environmental friendliness compared to their gasoline-powered counterparts.  I think this would be a great time to remind people that there’s a type of renewable fuel you can buy or even make yourself that is clean, domestically produced, and biodegradable with only some minor changes to your engine.