What is Biodiesel
Biodiesel is a form of alternative transportation fuel manufactured from renewable sources such as new or used animal fats and vegetable oils. Biodiesel burns cleaner than traditional petroleum-based diesel fuel. Pure biodiesel and biodiesel blended with petroleum diesel can be used to fuel diesel vehicles and engines.
Biodiesel is composed of long-chain mono alkyl esters, fatty acid methyl esters or fatty acid alkyl esters. Biodiesel is biodegradable, nontoxic and has physical properties similar to petroleum diesel.
Biodiesel can be produced from new as well as used animal fats and vegetable oils. Animal fats and vegetable oils are chemically reacted with an alcohol such as methanol and as a result, a chemical compound called fatty acid methyl ester is produced.
A variety of esterification technologies can be used to produce biodiesel. Animal fats and vegetable oils are filtered and preprocessed to eliminate contaminants and water. Using special pretreatment technologies, any free fatty acids can be destroyed or transformed into biodiesel.
The pretreated animal fats and vegetable oils are then mixed with an alcohol such as methanol and a catalyst such as sodium hydroxide. Triglycerides or the oil molecules are broken apart and reformed into glycerin and methyl esters. Glycerin and methyl esters are then separated and purified.
Schematic of biodiesel production path. (Source: Dept. of Energy)
B20 and B100 - Biodiesel Blends
B20, a blend containing twenty percent biodiesel and 80% petroleum diesel is the most common blend of biodiesel available in the United States. Engine modification is generally not required when using B20 and it can be used in nearly all diesel equipment. B20 is also compatible with most storage and distribution equipment.
The use of pure biodiesel might be best suitable for professional fleets with maintenance department. Pure biodiesel or B100 can be used in some engines manufactured after 1994 with parts such as hoses and gaskets produced from biodiesel-compatible materials.
Benefits of Biodiesel
Biodiesel can be produced domestically. Using biodiesel increases energy security and decreases our reliance on foreign oil. Biodiesel is also nontoxic and causes less damage when spilled or released to the environment.
Using biodiesel in conventional diesel engines dramatically decreases the amount of greenhouse gas emitted into the atmosphere. This is because the amount of carbon dioxide released during combustion is offset by the amount of carbon dioxide sequestered during the growth of the feedstock.
The amount of pollutants such as particulate matter, polycyclic aromatic hydrocarbons, carbon monoxide, nitrated polycyclic aromatic hydrocarbons and unburned hydrocarbons are also substantially reduced when biodiesel is used in conventional diesel engines.
Last update 14th June 2008