INSIDE THE DOT
South Dakota Department of Transportation
Potential Impact of Biodiesel on SDDOT
10/1/2002 - 5/20/2005
Biodiesel, which is a blend of diesel fuel and vegetable oil or animal fat that has gone through the transesterification process, is one of the alternative fuels available in the United States today. Biodiesel is produced by reacting vegetable oil or animal fat with alcohol in the presence of a catalyst such as potassium hydroxide or sodium hydroxide. The excess, catalyst and glycerin are removed through water washing, leaving the end product methyl ester (if reacted with methanol) or ethyl ester (if reacted with ethanol) and the byproduct glycerin. Several large companies and governmental agencies, such as the United States Postal Service, the United States armed forces, Florida Power and Light, and dozens of public transit systems from the bus system in Boise, Idaho to the Staten Island Ferry, use biodiesel fuels. In its 2002 session, the South Dakota legislature considered legislation mandating use of 2% (B2) biodiesel in all government vehicles exempt from fuel taxes, including all diesel vehicles in the South Dakota Department of Transportation (SDDOT) fleet. This legislation failed, but is expected to resurface during the 2003 legislative session. Before SDDOT moves to biodiesel fuels, it must determine the impact biodiesel might have on its vehicle fleet. B100, which has no diesel fuel added, is known to be an excellent solvent. Diesel fuel with as little as 5% ethyl or methyl ester, known as B5, may increase maintenance cost of fuel system due to the solvent action cleansing the vehicle fuel tank and lines during initial use. It is also known that biodiesel blends with concentrations at and above B20 have degraded certain elastomers in fuel systems. The SDDOT vehicle fleet includes many different types and ages of vehicles and equipment. Little information is available on older equipment using any grade of biodiesel, and the potential for degradation of elastomers in the fuel system and engine seals or gaskets may be greater. There also may be issues with engine and fuel system warranties. Storage, vehicle performance during cold weather, and potential for sludge formation also deserve investigation. The current method of splash blending (diesel fuel is pumped in truck transport tank first and the ethyl or methyl ester is pumped into tank next) is reported to work as long as fuel and ester are at or above 45 degrees F. At temperatures below 45 degrees F the two fuel components may not stay mixed, resulting in fuel filter plugging during cold weather. It is also reported that fuel in vehicle tanks may separate if the temperature falls below 0 degrees F when the vehicle is idle for long periods of time. Any time fuel is stored in storage tanks, above or below ground, the potential for water accumulation from condensation and sludge formation exists. An unknown with biodiesel is whether the formation of sludge will increase, decrease or remain about the same as regular diesel fuel. Finally, the Department needs to determine the financial impact of using biodiesel in its vehicle fleet. There may be additional costs beyond the $0.01 per percent ($0.02 for B2, $0.05 for B5, etc.) extra cost per gallon of fuel. Some of the other potential costs associated with using biodiesel in SDDOT vehicle fleet are equipment conversion, engine deterioration, fuel consumption, and an additional fuel storage tank at each shop site. On the other hand, there may be economic benefits, for example from reduced fuel system wear because of biodiesel's superior lubricity over low-sulfur and future mandated ultra-low sulfur diesel fuels .
1 Assess the compatibility of biodiesel fuel with SDDOT’s vehicle fleet and storage facilities
2 Determine the conversion and ongoing cost for SDDOT to use biodiesel in its vehicle fleet.
3 Estimate the overall economic impact to the Department if SDDOT were to use biodiesel in its vehicle fleet.
1 Meet with the project’s technical panel to review project scope, work plan, and draft survey of state transportation departments.
2 Review literature on previous and ongoing biodiesel research and potential problems that can occur with components in fuel systems.
3 Survey other state transportation departments that have used or are using biodiesel in their fleets to identify benefits, problems, and overall experience with using biodiesel.
4 Review SDDOT’s inventory of diesel vehicles and equipment to identify the potential nature and extent of compatibility problems with biodiesel.
5 Conduct swell and other appropriate tests on engine and fuel system components that may potentially be impacted by the use of biodiesel in 2%(B2), 5%(B5), and 20%(B20) concentrations.
6 Meet with drivers and mechanics at SDDOT’s Aberdeen, Sioux Falls, Pierre, and Rapid City shops to explain procedures and responsibilities for a twelve-month field comparison between vehicles operating on B5 and comparable vehicles operating on regula
7 Evaluate the operational performance of twelve SDDOT and county trucks (half with non-electronic controlled fuel injection systems and half with electronic controlled fuel injection systems) operating on B5 for twelve months at SDDOT’s Aberdeen, Siou
8 Conduct physical and chemical tests to assess fuel quality at: the time of delivery from the supplier; after storage in SDDOT’s underground storage tank at Rapid City and temporary, supplier-furnished, above-ground storage tanks at Pierre, Sioux Fall
9 Through review of vehicle maintenance records, engine oil analysis, forensic evaluation of failed engine or fuel system components, and interviews with drivers and mechanics involved in field testing, evaluate and compare maintenance histories of veh
10 Assess the costs, benefits, and overall economic impact to SDDOT’s using biodiesel at 2%, 5%, and 20% concentrations in its vehicle fleet. The assessment should consider future federal specification changes to diesel fuels, potential additional stora
11 Prepare an interim report that presents the preliminary findings, recommendations, and conclusions by December 15, 2002.
12 Prepare guidelines and specifications for the potential phasing in of biodiesel fuel at all SDDOT locations.
13 Prepare a final report and executive summary of the research methodology, findings, conclusions, and recommendations.
14 Make an executive presentation to the SDDOT Research Review Board at the conclusion of the project.
Copyright © 2017 State of South Dakota. All Rights Reserved.