Update 1/23/2009: MEG Corp, a fuel consulting company funded by the biofuels industry has issued a report on the situation. After examining affected fuel filters, their results indicate that the clogging was due to paraffin from the diesel portion of the fuel, rather than from the biodiesel component.
A chemiical engineering professor and biofuels expert at the University of Ottawa contacted by Dailytech said the resolvate technique used by MEG "sounds plausible", but that only an actual chemical analysis would give a definitive answer. The expert did confirm that, in the absence of expensive post-processing measures, the cold-weather performance of biodiesel does tend to be significantly worse than that of diesel.
MEG Corp tells Dailytech they are sending the fuel precipitate to the University of Alberta for actual analysis. We will report on their final conclusion when available.
Much of the U.S. has been experiencing record cold this winter. In Minnesota, that means temperatures well below zero. It also means state-mandated biodiesel fuel that turns into a thick gel, clogging fuel systems and preventing many diesel-powered vehicles from operating.
The combination of cold weather and biofuel has closed many school districts, with school buses being unable to operate. Some school systems are seeking a state waiver to allow them to temporarily use pure diesel. Others have found a faster solution: leave the buses running on idle all night, to keep the motors warm. Some tractor-trailer drivers are reportedly using the same measure as well.
Normal diesel will gel also, but at lower temperatures. Pure biodiesel begins to gel at around 32 degrees due to a much higher percentage of paraffin compounds. The state-mandated 2 percent biodiesel mix is good down to about 10 degrees, according to sources in the Minnesota DOT. Last year, the Minnesota Department of Agriculture announced a $300,000 grant to help biodiesel companies set up cold-weather blending measures, which includes mixing the fuel with kerosene or other additives.
Bill Walsh, director of communications for the state's Department of Commerce, defended the fuel, saying "this is not a biodiesel problem, it's a diesel problem."
The state is currently on a scaling plan that will gradually increase the percentage of biodiesel in fuel to 5 percent this year, then 20 percent by the year 2015. Minnesota's biodiesel is made primarily from soybean oil.
The snafu is expected to fuel debate over the biodiesel mandate, which when passed in 2005 pitted the state's soybean farmers against the trucking industry, who raised the specter of higher shipping costs due to increased fuel prices.