Are you considering a change to biodiesel?

Charlie Caudill
Equipment Maintenance Superintendent
City of Yuma, Arizona
Member, APWA Fleet Services Committee

The City of Yuma, Equipment Maintenance Division, has looked at various alternative fuel sources over the past few years in an attempt to find a fuel that would be easily adapted to our fleet. The problem with most alternative fuels is that they require extensive modification to either the vehicles or the fueling infrastructure. This prompted us to look for a fuel that could easily fit our current fleet with little or no changes. Biodiesel seems to be the product we are looking for that will fit our requirements.

We attended various seminars that touted the benefits of biodiesel and decided that during our next bidding cycle we would request bids for both B20 biodiesel (20 percent biodiesel, 80 percent diesel) and for B100 (100 percent biodiesel). We feel the improvements in emissions, reduction in odor, and quieter operation of diesel-powered vehicles will offset the cost difference in the fuel.

Biodiesel is a domestically produced, renewable fuel that can be used in unmodified diesel engines with the current fueling infrastructure. It is safe, biodegradable, and reduces serious air pollutants such as soot, particulates, carbon monoxide, hydrocarbons and air toxins. Performance, storage requirements, and maintenance are similar for biodiesel blend fuels and petroleum diesel. It contains no aromatics or sulfur, has a high Cetane number (good for ignition capabilities), and is a superior lubricant. In addition, regulated fleets can earn Energy Policy Act (EPAct) credits by purchasing biodiesel.

Biodiesel is made by chemically reacting alcohol with vegetable oils, fats, or greases. It is most commonly used in blends of two percent (partly for lubricity) or 20 percent (B20) biodiesel. It may also be used as pure biodiesel (B100). It is also a very good sulfur-free lubricant. B100 and biodiesel blends are sensitive to cold weather and may require special anti-freezing precautions, as conventional No. 2 diesel does. Biodiesel acts like a detergent additive, loosening and dissolving sediments in storage tanks, resulting in some plugging on dispensing equipment filters. Because biodiesel is a solvent, B100 may cause rubber and other components to fail in vehicles and equipment manufactured before 1994. B20 minimizes all these problems.

Biodiesel can be purchased from an increasing number of manufacturers and some petroleum distribution companies. The distribution efficiency should improve with the expanding market volumes. For a list of biodiesel suppliers, see the National Biodiesel Board website at

Presently B100 costs between $1.25 and $2.25 per gallon depending on purchase volume and delivery cost. Biodiesel is taxed as a diesel fuel, so taxes are added to the purchase price. At today's prices, B20 costs 13 to 22 cents more per gallon than diesel. However, because it uses existing infrastructure and vehicles, biodiesel may be a least-cost alternative for fleets regulated by EPAct. The cost difference is expected to shrink due to rising petroleum costs, new EPA rules requiring reduced sulfur content in diesel, and improvements in the biodiesel industry such as building larger plants with more efficient production technology.

In January 2001, DOE published the final rule for the use of biodiesel to fulfill the EPAct requirements. This rule allows covered fleets to use biodiesel fuel to fulfill up to 50 percent of their alternative vehicle (AFV) purchase requirements. According to the final rule, covered fleets will be allocated one biodiesel fuel use credit (the same as one AFV acquisition) for each 450-gallon purchase of B100. Credits will only be awarded if the fuel used contains at least 20 percent biodiesel and is used in vehicles weighing more than 8,500 pounds. If blends are used, only the biodiesel portion of the blend can be used to calculate the credit. For example, 2,250 gallons of B20 contains 450 gallons of pure biodiesel and would be allocated one AFV acquisition credit. No partial credits are allowed and the credits are good only for the year the fuel was used. The rules that apply are in the Federal Register for January 11, 2001. Biodiesel credit may not be saved or traded.

B100 has completed the Tier 1 and Tier 2 Health Effects testing requirements of the Clean Air Act. This testing concluded that emissions from biodiesel are non-toxic and pose little or no health risk to humans. Tests have shown that the cancer-causing potential of particulate matter from pure biodiesel is about 94 percent less than that of regular diesel and the risk from B20 is 27 percent less.

Biodiesel has several environmental benefits. Vehicles that run on this fuel emit fewer heavy hydrocarbons and less particulate matter, carbon dioxide, and carbon monoxide. Testing indicates, however, that nitrogen oxide (NOx) emissions may be slightly higher, but several recent tests of NOx reducing additives have shown promising results. Because biodiesel does not contain sulfur, it won't contribute to sulfur dioxide emissions or poison exhaust catalysts when used in 100 percent form, and it actually improves the efficiency of oxidative catalysts. During our search we have talked with various agencies that have tried, used, or are currently using biodiesel as a fuel source. Following is a summary of the results.

The Department of Energy, Nevada Test Site, according to Pete Scarafiotti, CEM, CAFM, Fleet Manager, has approximately 1,000 units currently operating successfully on biodiesel (B20). He said that the operation of the vehicles with the biodiesel has been one of those things that if you don't tell the operators of the change they won't notice it. He feels as others have stated, that biodiesel is an easy changeover for fleets. The change requires no infrastructure modification to accommodate the fuel. The one thing that might occur is that with the cleansing effect of the biodiesel there will be fuel filters that become plugged with old deposits; therefore, he recommends that before a fleet introduces biodiesel to their fuel storage tanks to have them cleaned of any deposits that might exist. Pete said that the major benefit for using the biodiesel was the reduction in the use of petroleum-based fuel.

Dave Burnside, Fleet Manager, Yavapai County, Arizona has recently converted to biodiesel for use in their fleet operation. Yavapai County is mostly a rural county with approximately 8,125 square miles of area. The elevation ranges from a low of 1,800 feet to 8,000 feet. They have 625 pieces of equipment in their fleet, which travel in excess of 6,250,000 miles a year. This fleet consists of a large number of off-road vehicles required to maintain the large number of miles of unimproved gravel roads. Dave feels that the biodiesel will improve his emissions on his off-road equipment fleet and reduce his petroleum-based fuels purchases. The utilization of biodiesel in the Yavapai County fleet is being done to establish a database to justify what kind of fuel will give the necessary benefits they are looking for. One interesting side note, the operators of the units that are using the biodiesel have yet to be told that they are using it. There have been no complaints to date.


  • National Biodiesel Board:; 1-800-841-5849
  • National Alternative Fuels Hotline:; 1-800-423-1DOE
  • Department of Energy, Office of Fuels Development:; Nohemi Zerbi, 1-202-586-1480.
  • National Renewable Energy Laboratory: K. Shaine Tyson, e-mail:
To reach Charlie Caudill, call (928) 343-8716 or send e-mail to