Biodiesel and Ethanol

Biodiesel by the Numbers

October 2010, Green Fleet Magazine - Feature

by - Also by this author

Biodiesel, a form of diesel fuel produced from vegetable oils or animal fats, is the only alternative fuel that runs in any conventional diesel engine. As such, biodiesel offers a straightforward path to a greener fleet.  

Manufactured domestically, biodiesel cuts emissions of carbon monoxide, sulfur, smog-producing particulate matter, and carbon dioxide - the main greenhouse gas causing global warming.

Through rigorous standards, testing, and evaluation, biodiesel shed its early misperception as a vegetable oil "homebrew." Still, there are challenges to implementation, including limited retail availability, fluctuating pump prices, maintenance and performance concerns, and vehicle warranty issues. Here's a "how-to guide" to determine if biodiesel will work in your fleet.

Know the Standards

Biodiesel is blended with petroleum diesel for most retail fuel applications. Common blends are B-2 (2-percent biodiesel), B-5, B-20, and B-100 (pure biodiesel). B-20 is the most commonly used biodiesel blend in the United States. This blend provides a good balance between material compatibility, cold weather operability, performance, emission benefits, and costs, according to the National Renewable Energy Laboratory (NREL).

Standards development body ASTM International sets minimum accepted values for fuel properties. The standard for petroleum diesel fuel is ASTM D975, while ASTM D6751 covers pure biodiesel (B-100) for blending with petrodiesel in levels up to 20 percent by volume.

Today, biodiesel must meet the ASTM D6751 standard to be legally defined and sold at retail fueling stations. Further, producers and marketers of biodiesel have created a voluntary accreditation program of biodiesel fuel. BQ-9000 is a quality systems program for biodiesel storage, sampling, testing, blending, shipping, distribution, and fuel management.

Though these quality checks and balances are the industry rule, it is a good idea to confirm through documentation that your supplier adheres to accepted standards and accreditation, said Steven Levy, managing director of Sprague Energy, a supplier of traditional and alternative fuels.

Check Engine Warranty

Check your vehicle engine manufacturers' warranty statements on biodiesel. Note that parts failures resulting from the use of any fuel are not covered.

Currently, most engine manufacturers state the use of up to B-5 blends will not void warranties, provided the fuel meets ASTM standards.
Chrysler, Cummins, Ford, General Motors, and International/Navistar have certified certain models for B-20. Other enginemakers are "currently completing research for B-20 support," according to the National Biodiesel Board (NBB) Web site,, which lists warranty statements for most manufacturers.

Fleets regularly use higher blends not covered in OEM warranty statements. While this runs the risk of voiding a warranty, fleet managers concentrate on the quality of the biodiesel to safeguard against parts failures.

Jim Evanoff, environmental protection specialist for Yellowstone National Park, said his supplier conducts his own tests in addition to ASTM certification. "We don't give it a thought, to be honest," Evanoff said. "We've never had a warranty issue." The park has been using varying blends of biodiesel for 15 years.

The New York City Department of Sanitation has been running B-5 for five years in close to 6,000 vehicles and started a B-20 pilot test in November 2009. Rocco DiRico, deputy commissioner for the Bureau of Support Services, reported no issues with engine malfunctions related to biodiesel.

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