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How Cold is Too Cold to Run Biodiesel? In addition to my SVO fuel habit, I also run commercial-grade biodiesel in my cars manufactured by US Biofuels in Rome, GA. US Biofuels uses rendered poultry fat exclusively as their feedstock for biodiesel production. There is a ready supply of poultry fat from the many poultry processing plants scattered throughout North Georgia and Tennessee. I purchase it at a fuel distributor in Marietta, GA.
S.A. White Oil Company According to the fuel distributor, this particular brand of B100 has a gel point of 38 degrees Fahrenheit in its unblended state. (pure B100 biodiesel) This is considered high compared to B100 produced from other plant-based, non-hydrogenated feedstock such as Canola, Peanut or Soybean oil. As a gel point test, I left my pump and filter in the driveway last night and checked it this morning to see how well the biodiesel would fair in the chilly morning weather.
Notice that, at some point in the night, crystals formed in the biodiesel. You can see in the picture above that most of the crystals are settling toward the bottom of the vessel. However, some are also floating toward the top. When biodiesel reaches its gel point, crystals begin to form in the solution and restrict flow of the fuel. Eventually, almost all of the solution solidifies at a temperature at or below the gel point. I did not test the temperature of the liquid in the filter but I will assume for this test that the temperature of the liquid is colder than the ambient temperature measured by the thermometer. (temperature is rising now after rising of the sun) Imagine this in your fuel tank, lines and fuel filter. This is what happens when you put B100 in your fuel tank and leave it in cold weather that dips below the gel point of the fuel. So, how do you know when it's too cold to run B100? I have several recommendations for you. Ask your fuel vendor - The best way to start research is to ask the fuel vendor for the gel point of the fuel you are purchasing. If they do not know the gel point, they can find out from the person at the facility that monitors this for proper dispensing of the fuel. If they can't provide the gel point, ask for the name of the supplier and call them. The producer/supplier can provide the average gel point for the fuel especially if their feedstock comes from a single source. (i.e., not WVO or diverse sources) I don't recommend doing this as your only research but it will get you started. Keep samples in your driveway - This is the most accurate way to check the gel point of your fuel since you are experimenting with the exact fuel lot that will go in your tank. Fill a glass mayonnaise jar or similar container about halfway full of the fuel you will be using. Place the glass jar near where you park your car or truck and leave it overnight. Check the viscosity and clarity of the fuel in the morning. This will help you determine whether the current blend of fuel (or B100) will work well in the current climate. If not, you can place several mayonnaise jars with different blends and see what works for your climate. (see below for more information on blending) Freezer tests - If you place a thermometer in the mayonnaise jar or smaller vessel and place it in the freezer, you can accurately check the gel point by monitoring the temperature of the fuel every few minutes until you detect crystallization. Creating a log sheet, taking pictures and doing this in one sitting over a couple of hours will give you accurate results. Once you have an understanding of the climate limits of your fuel, you can further experiment with reducing the gel point by blending the fuel. In order to counteract crystallization, biodiesel can be blended with petroleum diesel to lower the gel point of the fuel. This will help prevent crystallization until the blended fuel reaches the lower gel point. By combining fuel blending with the "mayonnaise jar in the driveway or freezer" methods above, you can create a mix of biodiesel and petroleum diesel that will work in your local climate. Note: If you will be traveling to a colder climate, make sure you take this into consideration when filling your vehicle with the blend of fuel for your current climate. You may need to reduce the ratio of biodiesel to petroleum diesel to accommodate the climate of your destination. Don't let this scare you off from using biodiesel. There are too many benefits to using biodiesel. With a little preparation, you can reap all of the benefits of this cleaner, renewable fuel source for your diesel engine! Currently, this is the only issue I've found that takes some care and preparation before using biodiesel. It is very manageable for most folks. For the Georgia climate, my plan is to run B50 blends from the first frost in the fall to the last frost in the spring. The rest of the year, I will use B100 for startup and WVO de-watered and filtered to 1 micron as my primary fuel. So, now to answer the question above, "How cold is too cold to run biodiesel?" Biodiesel can be used in any application that works with #2 diesel as long as you know the gel point of your fuel and are willing to test and blend properly to lower the gel point for your current weather conditions. I will prepare several blended samples at B5, B20, B50 and B75 mixtures and provide test results and pictures in a future revision to this article. Stay tuned! -VR
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