BIODIESEL PERFORMANCE

Successful alternative fuels fulfill environmental and energy security needs
without sacrificing operating performance. Operationally, biodiesel
performs very similar to low sulfur diesel in terms of power, torque, and fuel
without major modification of engines or infrastructure.
Biodiesel offers similar power to diesel fuel. One of the major advantages of biodiesel is
the fact that it can be used in existing engines and fuel injection equipment with little
impact to operating performance. Biodiesel has a higher cetane number than U.S.
diesel fuel. In over 15 million miles of in-field demonstrations biodiesel showed similar
fuel consumption, horsepower, torque, and haulage rates as conventional diesel fuel.
Biodiesel provides significant lubricity improvement over petroleum diesel fuel. Lubricity
results of biodiesel and petroleum diesel using industry test methods indicate that there
is a marked improvement in lubricity when biodiesel is added to conventional diesel
fuel. Even biodiesel levels below 1 percent can provide up to a 65 percent increase in
lubricity in distillate fuels.
Compatibility of biodiesel with engine components. The recent switch to low sulfur
diesel fuel has caused most OEMs to switch to components suitable for use with
biodiesel, but users should contact their OEM for specific information. In general,
biodiesel will soften and degrade certain types of elastomers and natural rubber
compounds over time. Using high percent blends can impact fuel system components
(primarily fuel hoses and fuel pump seals), that contain elastomer compounds
incompatible with biodiesel. Manufacturers recommend that natural or butyl rubbers
not be allowed to come in contact with pure biodiesel. Biodiesel will lead to
degradation of these materials over time, although the effect is lessened with biodiesel
blends. If a fuel system does contain these materials and users wish to fuel with pure
biodiesel, replacement with compatible elastomers is recommended.
Biodiesel in cold weather. Cold weather can cloud and even gel any diesel fuel,
including biodiesel. Users of a 20 percent biodiesel blend will experience an increase
of the cold flow properties (cold filter plugging point, cloud point, pour point) of
approximately 3 to 5° Fahrenheit. Precautions employed for petroleum diesel are
needed for fueling with 20 percent blends. Neat (100 percent) biodiesel will gel faster
than petrodiesel in cold weather operations. Solutions for winter operability with neat
biodiesel are much the same as that for low-sulfur #2 diesel (i.e., blending with #1
diesel, utilization of fuel heaters, and storage of the vehicle in or near a building).
These same solutions work well with biodiesel blends, as do the use of cold flow
improvement additives.