What is Biodiesel?

Biodiesel is defined as the Mono-Alkyl Esters of fatty acids derived from vegetable oils or animal fats.

An easier way to understand biodiesel is to understand it as a product that is obtained when a vegetable oil or animal fat is chemically reacted with an alcohol to produce fatty acid alkyl esters. A catalyst such as sodium or potassium hydroxide is required. Glycerol is produced as a co-product. Usually the approximate proportions of the reaction would be as follows: 

100 pounds of vegtable oil + 10 pounds of methanol = 100 pounds of biodiesel & 10 pounds of glycerol 

Biodiesel is usualy made from some of the following feedstocks:

-Vegtable oils, such as corn oil, canola oil (an edible variety of rapeseed oil), cottonseed oil, mustard oil, palm oil, etc.

-Restaurant waste oils, such as frying oils (usually called WVO or Waste Vegetable Oil)

-Animal fats, such as beef tallow or lard

-Trap grease (from restaurant grease traps), float grease (from waste water treatment plants), etc. 

All animal fats and vegetable oils consist primarily of triglyceride molecules.

Transesterification is the process of reacting a triglyceride molecule with an excess of alcohol in the presence of a catalyst (NaOH, KOH, etc...) to produce fatty esters and glycerol. The mixture of fatty esters produced in this reaction is referred to as biodiesel.