Biodiesel Cold Weather Blending Study

Title: Biodiesel Cold Weather Blending Study

Principle Investigator: A consortium of researchers

Year: 2003

Lay Summary/Industry Summary: Increased use of biodiesel has created some handling challenges for bringing blended fuels to the consumer. The most immediate handling concern for blenders is assurance that diesel fuels and biodiesel can be blended uniformly and in a single phase. More specifically, blenders need guidelines and parameters for blending diesel fuel and biodiesel in colder climates. Neat biodiesel has a much higher cloud point than conventional diesel fuels and this can impact handling procedures. This concern became a priority following the passage of a bill in Minnesota that required all on-highway diesel fuels to contain at least 2% biodiesel as early as July 1, 2005.

In response to the need in Minnesota, the National Biodiesel Board established a Biodiesel Cold Flow Consortium to study the blending properties of biodiesel. Members of the consortium included petroleum marketers, biodiesel producers, fuel blenders, and other experts and interested parties. The members designed a project to investigate this cold flow problem. The project goal was to define operating parameters for blending biodiesel with diesel fuel at a variety of temperatures, including those seen in the wintertime in Minnesota.

To achieve this goal, a small blending test rig was designed to simulate splash and proportional blending at the terminal. Unadditized No. 1 and No. 2 diesel fuels were selected, along with three biodiesels with a range of cold flow properties. The test temperatures were determined using Minnesota winter climate data. All testing focused on preparing 2 volume percent biodiesel blends.

Splash blending tests were based on visual observation of wax crystal formation and are thus qualitative. To ensure quantitative data was obtained, differential pressure drop measurements were collected. These measurements compared the pressure drop of neat diesel fuel through a filter with the pressure drop created by B2 blends at various
tern peratures.

Results from the testing showed that the biodiesel must be kept at least 1O”F above its cloud point to successfully blend with diesel fuels in cold climates. Because generic, unadditized fuels were used in this project, the actual temperatures of the fuels will need to be determined on an individual basis.