Anyone familiar with biodiesel understands one inherent limitation: it hates cold weather. This weekend I had my first experience with the ‘cold-flow properties’ of this alternative fuel. Here’s what happened:

I was speeding along through Idaho on my way to the Sundance Film Festival in Park City, Utah. As you may know, the plains of southern Idaho are bloody COLD, and the ambient air temperature hovered in the low teens. Fortunately for me, I own a hybrid vehicle–actually, it’s a pentbrid: It can run on diesel, kerosene mixtures (aka diesel No. 1), biodiesel, straight vegetable oil (SVO), and automatic transmission fluid (ATF), although the last one is kind of disgusting (but you have to love the integrity of old diesel engines). Nevermind all of that; the important point for this discussion is I have a heated fuel system (tank, fuel lines, filter, etc.) running in parallel with the regular diesel fuel system. This setup allows me to drive around on plain old vegetable oil (for more background on this, please see this website) in normal to extremely cold temps.

It’s amazing how a short sequence of seemingly insignificant but nevertheless important mistakes can bring about catastrophic failure. This is an important principle for surviving in the wilderness, operating a nuclear power plant, and, also, driving around on an ‘alternative fuel’.

I drove for 700 miles on hot vegetable oil and had no trouble. Unfortunately for my travel budget and subsequently my ETA, I ran out of vegetable oil and had to switch back to running on the regular diesel system (I can easily toggle between these two systems with the flip of a switch)–but the stock diesel system is NOT heated. After a few minutes, I noticed a significant power loss that dropped my speed to 50 mph. By stomping on the gas pedal, I could get back up to 55 before the vehicle stumbled and slowed down again–a common symptom of a partially-clogged fuel filter. Small wax crystals can begin to form in regular diesel fuel below 10 degrees F (this is called “clouding up”), and at cold enough temperatures, the fuel will completely freeze or ‘gel up’. Certain additives can prevent this, and regular diesel can be mixed with kerosene (a thinner liquid) to create “winterized diesel”. Biodiesel itself starts to cloud up at much higher temperatures than diesel, depending on the feedstock (virgin soybean oil, waste cooking oil, etc.), and mixing biodiesel with diesel greatly affects the fuel’s cold weather properties.

Sequential Biodiesel of Oregon recommends a 50% biodiesel / 50% diesel mix (called B50) for temperatures between 20-40 degrees F. A mixture of 20% biodiesel / 80% diesel (B20) is recommended for temperatures below 20 degrees F.

My big mistake was neglecting to top off the B50 mixture in my fuel tank with more diesel before leaving temperate Corvallis, Oregon. When I switched back to this biodiesel-rich mixture in Idaho, the ambient air temperature was around 8 Degrees F, with a wind chill at 55 mph of God knows how cold. Within 10 minutes my fuel filter clogged and my engine seized up on completely frozen fuel. I coasted to the side of the freeway where the engine refused to turn-over–it was a cold, dark silence.

This is not a fun way to finish off a 15 hour drive.

After an $85 after-hours tow off the freeway to a truck stop, I had a very long winter night to reflect on the whole situation. By early afternoon of the next day I was able to get a jump start, but it took a good 35 minutes of cranking to get that engine running properly. I had to add an anti-gelling additive to the fuel, make sure the tank was topped off with more diesel, and burn out all the clogged fuel still in the engine.

The moral of the story? Well, plan ahead when using biodiesel in cold weather. Living green at the edge of the mainstream can be full of surprises, and it often requires a novel and thoughtful approach to routine tasks. You make mistakes, learn from them, and move on with a greater appreciation and commitment to your ideals. That’s what it’s all about.

DOE’s Biodiesel Handling and Use Guidelines/Cold-Flow properties: http://www.nrel.gov/vehiclesandfuels/npbf/pdfs/40555.pdf

Sequential Biodiesel’s recommendations for cold weather biodiesel blending: http://www.sqbiofuels.com/winter_use.htm