UPDATE:
Lab tests show the problem was may be caused by paraffin wax – a derivative of Diesel Fuel. See this report:
http://nbb.grassroots.com/resources/BloomingtonBusReport.pdf
This bus design does not allow for heating of the filter by the engine.
h/t to Kum Dullison
UPDATE2: There is new information, from E.M. Smith in comments, citing that possibility of “methylester that solidifies at >10F vs Paraffin wax” could be a contributor. The lab did not test for that, so the question of fuel quality remains unresolved.
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Excerpts from the Minneapolis Star Tribune, January 16th 2009
Biodiesel fuel woes close Bloomington schools
“All schools in the Bloomington School District (Minnesota) will be closed today after state-required biodiesel fuel clogged in school buses Thursday morning and left dozens of students stranded in frigid weather, the district said late Thursday.
Rick Kaufman, the district’s spokesman, said elements in the biodiesel fuel that turn into a gel-like substance at temperatures below 10 degrees clogged about a dozen district buses Thursday morning. Some buses weren’t able to operate at all and others experienced problems while picking up students, he said.
We had students at bus stops longer than we think is acceptable, and that’s too dangerous in these types of temperatures,” Kaufman said.”
. . .
The decision to close school today came after district officials consulted with several neighboring districts that were experiencing similar problems. Bloomington staffers tried to get a waiver to bypass the state requirement and use pure diesel fuel, but they weren’t able to do so in enough time, Kaufman said. They also decided against scheduling a two-hour delay because the temperatures weren’t expected to rise enough that the problem would be eliminated.
In 2005, a new requirement went into effect that all diesel fuel sold in Minnesota had to contain 2 percent biodiesel. Kaufman said that some school districts keep their buses in temperature-controlled garages, and that the First Student bus service, which contracts with several metro-area school districts, keeps its buses in garages or idles them through the night.
Meanwhile, in other news:
Minnesota Boosts Biodiesel Initiative from 2 to 20%
(h/t to Popular Technology)
blubi (16:14:45) :
“Call me obtuse but WTF is gas (oil/petrol the name varies by country) not a biofuel?
I just checked on wiki and they claim biofuel is defined as “recently dead biological material”, which sounds like Orwellian doublespeak. As opposed to evil long-dead biological material?
Here´s a suggestion: don´t let them dictate vocabulary, once you concede that you´ve lost a major battle. Bio is biological, carbon based. Make them define them as recently dead, sustainable, Gore´s politically correct fuels, or whatever.”
You are right that both dino-diesel and bio-diesel are carbon based. The difference is that petroleum has been underground for a few million years, and bio-diesel probably did die just a short time ago. If it is animal-based, the critters probably died within a few days of being rendered into oil. If plant-based, the seeds or whatever could have been stored somewhere for a few weeks to a few months. With algae-oil, I think it is a very short trip from the sunshine to the processing plant.
Another way to distinguish the two is fossil fuel vs renewable fuel.
Horse hockey
In an entire state that requires a 2% bio mixture in all diesel this one little school district had some buses of a certain type that didn’t operate properly.
This is a no-brainer. The school system’s mechanic (or whoever pumped the summer blend into the offending buses) screwed up. You know it, and I know it.
REPLY: No I don’t “know it”. I see this is going nowhere, you are now speculating and blaming someone rather than doing an analysis. I’m going to give this thread a time out for awhile. – Anthony
comments are open again
Kum Dollison (20:15:22) :
In an entire state that requires a 2% bio mixture in all diesel this one little school district had some buses of a certain type that didn’t operate properly.
This is a no-brainer. The school system’s mechanic (or whoever pumped the summer blend into the offending buses) screwed up. You know it, and I know it.
I’m sorry, but it is not a no-brainer. There is no reason to think there was #2 Diesel (‘summer’) in the tanks. Buses are used prior to January. Fuel turns over fairly quickly. And as I stated above, at the posted temperatures all the buses would have fuel problems with straight #2 due to cold fuel lines, even if no paraffin was in the fuel (no cloud point or cold filter plugging point issues, just pour point issues). They didn’t, ergo not #2.
Please take a look at the Canada analysis I referred to above. The charts clearly show 2 things:
1) BioDiesel (methylester, chemically) has very high cloud points compared to D2 (#2 or ‘summer’ Diesel). Some as high as room temperature.
2) Blends with #2 or even #1 (kerosene or ‘winter Diesel’) have an elevated pour point and an elevated cloud point. This is because the bioDiesel blended in forms ‘wax like’ crystals at higher temperatures.
Now re-read the lab test. There was no chemical analysis done. They looked at a ‘wax substance’ and observed it melt. I’ve done this many times with bioDiesel. Pure, 100%, no paraffin in it, made myself known history methylester made from pure virgin bought at the store soybean oil, corn oil, and other oils. It looks just like a slightly yellowish paraffin melting. It is not possible to tell the two apart by eye. (One tests their own fuel for cloud point by placing it in the fridge since it can freeze solid in the freezer…)
Given this, the most likely scenario is that the fuel started to cloud as the methylester (bioDiesel) started to come out of solution as a solid (‘crystalize’). The buses with filters heated by the engine were able to run long enough to get return (bypassed excess) fuel back to the fuel tanks and start warming the fuel system. Buses with cold filters clogged up prior to enough heat making it into the fuel tank mass and back down the fuel lines. Cars and commercial trucks have much shorter runs from engine to tank and warm the fuel system faster. Buses are the canaries…
The buses with the weakest system went down first with marginal cold spec fuel in an unusual cold snap.
Per the assertion that these were the only vehicles having an issue. It just doesn’t work that way. In EVERY cold snap, many folks have a ‘failure to start’ issue. I’ve had 2 or 3. None of them made the paper.
One was my story of a tank of #2 from a warm valley (they don’t do #1 in California’s warm areas at any time of year) and a long drive to cold Tahoe snow. Another was a single dead glow plug (starts OK warm, need ’em all when cold). A third was when I ran a way too ‘thick’ mix of bio-fuel in too cold a temp for it.
These things are just not newsworthy and you will never hear about them in the paper. Nor have you heard of the dozens of truckers in Alaska each year who have to warm their fuel system with blowtorches and bonfires…
That it was school buses with kids waiting made it a news story.
Again, look at the cloud and pour point graphs in the Canada paper. As legal mandates force more bioDiesel into the winter mix, more of these events will happen. It is inevitable. Each type of equipment and filter has it’s limits for clouding. As viscosity, clouding, CFPP issues, et. al. hit ever more classes of equipment eventually the ‘issue’ will be addressed.
This is what we went through in California with the super early introduction of ultra low sulphur Diesel and the need to replace seals with viton and nitrile materials. The Canaries go first, then the rest of us get hit.
I would predict that the ‘fix’ will be simple. To meet ASTM fuel specs AND bioDiesel percentages, more refineries will run bio-oils and fats through their hydrotreaters to make bioDiesel that is alkane, and not methylester based. Unfortunately, this will not happen as long as people believe that there is no problem to fix…
My interest in all this is simple: I want bioDiesel. I do not want to be stuck by the side of the road every time it gets cold while the government powers that be figure out the fuel chemistry I already know and fix their mandates.
At this point I’ve said all I can contribute on this point and I’m retiring from this thread. There is no sense continuing to flog this. The facts, data, references et. al. are posted above for anyone to see. I can add no more.
Folks, this issue has been pretty much resolved in biodiesel’s favor.
See Wednesday’s editorial in the Star Tribune, the newspaper that first reported this (yes, the op/ed should have mentioned that fact). See my post at Gas 2.0. There are many other sources as well.
Bob Moffitt
Communications Director
Clean Fuel & Vehicle Technologies program
American Lung Association of Minnesota