EPA420-F-06-044 

October 2006 

Alternative Fuels:


Biodiesel 

Biodiesel is a renewable fuel produced from agricultural resources such as vegetable oils. In the United 

States, most biodiesel is made from soybean oil; however canola oil, sunflower oil, recycled cooking oils, 

and animal fats are also used. 

How It's Made 

To make biodiesel, the base oil is put through a process called 

"esterificiation." This refining method uses an industrial 

alcohol (ethanol or methanol) and a catalyst (substance that 

enables a chemical reaction) to convert the oil into a fatty-acid 

methyl-ester fuel (biodiesel). 

Biodiesel in its pure form is known as "neat biodiesel" or 

B100, but it can also be blended with conventional diesel, most 

commonly as B5 (5 percent biodiesel and 95 percent diesel) 

and B20 (20 percent biodiesel and 80 percent diesel). Biodiesel 

is registered with the U.S. Environmental Protection Agency 

(EPA) and is legal for use at any blend level in both highway 

and non-road diesel vehicles. 

Most diesel engines can run on biodiesel without needing any 

special equipment. If you are interested in using biodiesel in 

your vehicle or equipment, check with the manufacturer for 

any recommendations and information regarding engine 

warranties. In addition, once you have determined the proper 

blend for your vehicle, make sure to purchase your fuel from a 

reputable dealer selling commercial grade biodiesel. 

Biodiesel -vs- Vegetable Oil 

In 1895, Dr. Rudolf Diesel invented the diesel engine with the 

intention of running it on a variety of fuels, including vegetable 

oil. In fact, when he demonstrated his engine at the World 

Exhibition in Paris in 1900, he fueled the vehicle with peanut 

oil. However, biodiesel and vegetable oil are very different. 

Raw vegetable oil or recycled greases (also called waste 

cooking oil) that have not been processed into esters are not 

biodiesel, and are not registered by EPA for legal use in 

vehicles. In addition, vehicles converted to use these oils 

would likely need to be certified by the EPA; to date EPA 

has not certified any conversions. These conversions may 

also violate the terms of the vehicle warranty. For more 

information on the certification process, please visit EPA's 

Web site at: www.epa.gov/otaq/cert/dearmfr/cisd0602.pdf. 

Performance 

Vehicles have similar horsepower and torque as conventional 

diesel when running on biodiesel. Chemically speaking, 

biodiesel has a higher cetane number, but slightly lower 

energy content than diesel. To the average driver, this means 

better engine performance and lubrication, but a small 

decrease in fuel economy (2-8 percent). Biodiesel vehicles 

can also have problems starting at very cold temperatures, 

but this is more of an issue for higher percentage blends such 

as B100 and easily solved the same way as with 

conventionally fueled vehicles -by using engine block or fuel 

filter heaters or storing the vehicles in a building. 

Availability 

In 2004, 25 million gallons of B100 were sold. By 2005, that 

number had tripled. Today, approximately 600 fleets 

nationwide use biodiesel blends in their diesel engines, and 

biodiesel is available in its various blends at approximately 

800 locations across the United States. A complete list of 

stations is available at www.biodiesel.org. 
Affordability 

The price of biodiesel blends varies depending on geographic 

area, base material (corn, soybeans, etc.), and supplier. 

Although biodiesel can cost more than petrodiesel, diesel 

drivers can transition to biodiesel without purchasing new 

vehicles. In the case of fleets, managers can transition to 

biodiesel without acquiring new spare parts inventories or 

rebuilding refueling stations. 

Maintenance 

Generally, the use of biodiesel does not cause many 

maintenance issues. However, when used for the first time, 

biodiesel can release deposits accumulated on tank walls and 

pipes from previous diesel fuel, initially causing fuel filter 

clogs. As a result, vehicle owners should change the fuel filter 

after their first tank of biodiesel. Also, biodiesel can degrade 

rubber fuel system components, such as hoses and pump seals. 

This is especially true with higher-percentage blends, and older 

vehicles. Many newer vehicles have biodiesel-compatible 

components, but it is best to consult your owner's manual or 

contact your vehicle manufacturers for specific information. 

Benefits 

Biodiesel has a number of important benefits. As an alternative 

to diesel, it can help reduce U.S. dependence on foreign oil. 

Biodiesel also provides significant greenhouse gas (GHG) 

emission reductions. B100 reduces lifecycle greenhouse gas 

emissions by more than 50 percent, while B20 reduces GHG 

emissions by at least 10 percent. 

In addition, biodiesel offers several criteria emissions benefits 

for the existing vehicle fleet. It reduces emissions of carbon 

monoxide, particulate matter (PM), and sulfates, as well as 

hydrocarbon and air toxics emissions. 

A 2002 EPA summary analysis of existing data suggests 

vehicles using biodiesel may emit slightly more nitrogen oxide 

(NOx) (about 2% for B20 and 10 percent for B100). 

Subsequent studies have yielded mixed results, with some 

showing small increases and others showing small decreases. 

EPA plans a further investigation to fully assess this issue, 

including the emissions impact of using biodiesel in vehicles 

equipped with PM traps and NOx aftertreatment designed to 

meet strict new emission standards. 

For More Information 

EPA Grow & Go Web Site: www.epa.gov/smartway/growandgo 

EPA Alternative Fuels Web Site: www.epa.gov/otaq/consumer/fuels/altfuels/altfuels.htm 

DOE Alternative Fuels Data Center Web Site: www.eere.energy.gov/afdc 

National Biodiesel Board Web Site: www.biodiesel.org 

http://www.epa.gov/smartway EPA420-F-06-044