Fact Sheet April 2005

Biodiesel Blends 

lower than the engine’s minimum requirements can cause 

rough engine operation and may be more difficult to start, 

especially in cold weather or at high altitudes. Low cetane 

fuels may increase engine deposits resulting in more smoke, 

increased exhaust emissions, and greater engine wear. 

With proper fuel tank maintenance and fuel blending, 

biodiesel blends of B20 or lower can be used in any diesel 

engine—including those with advanced fuel injection 

systems—without reducing reliability or durability. 

User feedback suggests that maintenance requirements 

for diesel engines operating on biodiesel blends of B20 

or less are identical to those operating on standard diesel.

Do Biodiesel Blends Reduce Emissions?

EPA research shows that biodiesel reduces most emissions 

from unmodified diesel engines (see chart). The amount 

that emissions are reduced depends on the blend level. 

For example, B100 produced from soybean oil reduces 

life cycle CO2 emissions by 78% compared to petroleum 

diesel. This effect is linear with blend level so a B5 blend 

reduces life cycle CO2 emissions by 3.8%. Low-level 

blends will also cause small reductions in emissions of 

hydrocarbons, carbon monoxide, particulate matter, and 

harmful air toxics.

Oxides of nitrogen (NOx), which contribute to smog 

formation, may increase slightly when biodiesel is used. 

Numbers vary, however B20 is believed to increase NOx

by 2%-4%. A number of biodiesel researchers are working 

on fuel additives to address this problem. For blend levels 

of 5% or lower, the NOx increase is negligible.

In 2003, U.S. net petroleum imports exceeded 11 million 

barrels of oil per day. Almost 24% of that imported crude 

oil is refined into diesel fuel and heating oil for use in 

U.S. trucks, boats, and heavy equipment.1 We can displace 

a significant amount of petroleum by adding low levels of 

biodiesel to the diesel we use every day for transportation, 

industry, and recreation. According to the Energy Information Administration, the United States consumed approximately 36 million gallons of biodiesel in 2004. 

Biodiesel is a renewable diesel replacement fuel that is 

manufactured from domestically produced oils such as 

soybean oil, recycled cooking oils, or animal fats. To 

manufacture biodiesel, these fats and oils are chemically 

reacted with a short chain alcohol (such as methanol) and 

a catalyst to produce biodiesel and a glycerin co-product. 

Biodiesel can be used alone (B100) or blended with 

petroleum diesel in any proportion. 

The most popular biodiesel blends are B20 (20% biodiesel), which can be used for Energy Policy Act of 1992 

(EPAct) compliance, and B5 or B2. Any diesel engine can 

operate on these blends with few or no modifications. 

When used in low-level blends of 5% biodiesel (B5) or 

below, biodiesel is transparent to the user. When biodiesel 

is used as B20, the user may experience a 1%-2% 

decrease in power, torque, and fuel economy; however 

these changes are usually not noticeable.

Can Biodiesel Improve Engine Performance?

Biodiesel’s superior lubricating properties can reduce wear 

in diesel engines. Bench scale tests have shown that 1% 

biodiesel can improve the lubricity of diesel fuel by as 

much as 65%.

The lubricity of biodiesel will become increasingly 

important because EPA regulations will require the use 

of ultra-low sulfur diesel fuels in all U.S. highway diesel 

engines by 2006. Unfortunately, ultra-low sulfur diesel 

fuels can have poor lubricating properties. Low levels of 

biodiesel used as a lubricity additive can help solve this 

problem.

Biodiesel also has a higher cetane number than most diesel 

fuel. Cetane measures the tendency of diesel to autoignite 

in an engine, and is comparable to the octane number for 

gasoline. Higher cetane fuels have shorter ignition delay 

periods than lower cetane fuels. Fuels with a cetane number 

Clean Cities and Biodiesel Blends

Blending relatively low levels of alternative fuels with conventional

fuels reduces petroleum use and is therefore an important strategy in 

the Clean Cities portfolio. Clean Cities tactics to promote fuel blends 

include:

• Training coordinators on the benefits of biodiesel blends and

 teaching them how to determine which blends make sense 

locally or regionally. 

• Encouraging coalitions to develop outreach plans to educate 

heavy-duty fleets about biodiesel blend benefits. 

• Working with state and local governments to explore 

opportunities to expand mandates and other programs 

 for increasing biodiesel blend use.
Clean Cities

does not make B20 an alternative fuel, but gives one 

credit for every 450 gallons of pure biodiesel used in 

biodiesel blends. To read about this regulation, visit 

www.eere.energy.gov/afdc/pdfs/FedRegBioFinal.pdf.

Finally, some states have passed legislation that either 

reduces fuel excise taxes or provides other incentives for 

biodiesel use or sale. To find out if your state has passed 

biodiesel legislation, contact your local tax authority, or 

visit www.eere.energy.gov/afdc/laws/incen_laws.html.

Is Biodiesel Readily Available?

Biodiesel is available in all 50 states. An increasing 

number of retailers, petroleum distributors, and biodiesel 

distributors are offering biodiesel blends. The National 

Biodiesel Board (NBB) maintains a list of registered fuel 

marketers and retail fueling sites on its website at 

www.biodiesel.org.

Where Can I Get More Information?

The U.S. DOE’s Alternative Fuels Data Center at 

www.eere.energy.gov/afdc/ is a vast collection of information on alternative fuels and alternative fuel vehicles.

The U.S. Department of Energy’s Office of Energy 

Efficiency and Renewable Energy website at 

www.eere.energy.gov/biomass/ contains information 

on biodiesel and ethanol production and policy.

The National Biodiesel Board is the national trade 

association representing the biodiesel industry. Its 

website, www.biodiesel.org, serves as a clearinghouse 

of biodiesel related information.

The National Renewable Energy Laboratory’s 

Nonpetroleum Based Fuels website, located at 

www.nrel.gov/vehiclesandfuels/npbf/, provides links 

to a variety of biofuels documents.

The Environmental Protection Agency’s Biodiesel 

Emissions Analysis Program at www.epa.gov/otaq/models/

biodsl.htm contains emissions and performance data 

for biodiesel.

Who Regulates Biodiesel Quality?

The American Society for Testing and Materials (ASTM) 

has developed specifications for B100 that will be blended 

with diesel fuel to make low-level biodiesel blends. ASTM 

specification D6751-03 is intended to ensure the quality of 

biodiesel used in the United States, and any biodiesel used 

for blending should meet this specification. Biodiesel 

meeting ASTM D6751-03 is also legally registered as 

a fuel and fuel additive with the U.S. Environmental 

Protection Agency. For a complete list of ASTM biodiesel 

requirements, see the 2004 Biodiesel Handling and Use 

Guidelines at www.nrel.gov/docs/fy05osti/36182.pdf.

In addition, the National Biodiesel Board is instituting a 

quality assurance program for biodiesel producers and 

marketers. To learn more about the BQ-9000 program, 

visit the National Biodiesel Board at www.biodiesel.org.

Are Incentives and Credits Available for Biodiesel?

B5 generally costs about 5 cents more per gallon than No. 2

diesel. In October 2004, however, the President signed a 

bill that contained a biodiesel tax incentive for biodiesel 

blenders. Experts expect that this tax incentive will lower 

the price of biodiesel blends but the full effect of implementing this regulation is not yet known. To learn more 

about this tax incentive, visit the National Biodiesel Board 

at www.biodiesel.org.

Additionally, in January 2001, federal, state, and certain 

fuel provider fleets became eligible for EPAct credits 

for using biodiesel blends of at least 20%. This rule 

For more information about Clean Cities visit www.eere.energy.gov/cleancities

Prepared by the National Renewable Energy Laboratory (NREL)

NREL is a U.S. Department of Energy National Laboratory

Operated by Midwest Research Institute • Battelle

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DOE/GO-102005-2029 • April 2005

20%

10%

0%

-10%

-20%

-30%

-40%

-50%

-60%

-70%

-80% 0 20 40

Percent biodiesel

Percent change in emissions

60 80 

HC 

CO

PM 

NOx

100

Basic Emission Correlation. Average emission impacts of 

biodiesel for heavy-duty highway engines. Source: U.S. EPA2.

1 U.S. Energy Information Administration, “Monthly Energy Review, October 2004,” 

 www.eia.doe.gov/emeu/mer/contents.html.

2 U.S. Environmental Protection Agency, (2002) “A Comprehensive Analysis of Biodiesel

 Impacts on Exhaust Emissions, Draft Technical Report,” EPA420-P-02-001,

 www.epa.gov/otaq/models/analysis/biodsl/p02001.pdf.