Biodiesel is a liquid fuel derived from vegetable oils, or animal fats, which consists of mono-alkyl esters of long chain fatty acids (or fatty acid methyl esters). It has fueled diesel engines since they were invented by Rudolph Diesel in the late 1800’s.
Biodiesel is produced through transesterification, a process where lipids (fats and oils) are mixed with alcohol (commonly methanol) and a catalyst (commonly sodium hydroxide). The result: methyl esters and glycerin. Once separated, the methyl esters serve as biodiesel fuel, and the glycerin can be used in soap and other products. Common biodiesel feedstocks (oil and fats sources) include: soybeans, rapeseed, algae, vegetable oils, & animal fats. All biodiesel, regardless of feedstock, is required to meet ASTM D 6751 standards.
Biodiesel has a positive energy balance - at least 3.24 units of energy are gained for every unit of energy needed to produce a gallon of biodiesel. Biodiesel also produces significantly fewer emissions: unburned hydrocarbons, toxics, CO2, CO, particulates. A U.S. Department of Energy study showed that the production and use of biodiesel, compared to petroleum diesel, resulted in a 78.5% reduction in carbon dioxide.
It is a domestic, renewable, biodegradable, nontoxic, clean-burning replacement for petroleum diesel fuel, which can be manufactured from wide range of vegetable oils, animal fats, or recycled restaurant greases. It significantly reduces greenhouse gas emissions, and is essentially free of sulfur and aromatics. Biodiesel also has higher cetane, lubricity, and oxygen content, thereby enhancing fuel performance - biodiesel has the highest BTU content of the alternative fuels. Additionally, it is the only diesel substitute to have fully completed Tier I and Tier II Health Effects Testing as required by the Clean Air Act Amendments of 1990.
Biodiesel contains no petroleum, but it can be blended with petroleum diesel. Biodiesel blending uses a system known as the "B" factor to state the amount of biodiesel in any fuel mix: "BXX" with "XX" representing the percentage of biodiesel contained in the blend. Biodiesel can be blended with petroleum diesel in any percentage:
100% biodiesel is referred to as B100
20% biodiesel, 80% diesel is labeled B20
5% biodiesel, 95% diesel is labeled B5
2% biodiesel, 98% diesel is labeled B2
B20 is the most common biodiesel blend for fleet use. Biodiesel (B100) contains about 8% less energy per gallon than petroleum diesel. For B20, this could mean a 1% to 2% difference. However, most users report no difference or even improved fuel economy with blended biodiesel.
Note: Biodiesel and Ethanol are two different fuels. Ethanol is an alcohol that is intended for use in gasoline powered engines, whereas biodiesel is an ester designed for use in diesel engines. Both fuels have different compositions, properties and benefits.
Biodiesel Fueling Stations
UCCC Biodiesel Vehicle Technologies Page
Alternative Fuel Data Center - Biodiesel
U.S. Dept. of Energy - EERE - BioEnergy
FuelEconomy.Gov - Biodiesel
National Biodiesel Board
ASTM International - Standards
BioFuels Water Footprint Tool - Argonne Nat. Lab
Resources referenced on this website are presented for informational purposes only,
UCCC does not necessarily recommend or endorse these entities.