Both diesel and biodiesel fuels contain certain hydrocarbon molecules that combine to form paraffin wax. The temperature at which these molecules begin to crystalize is called the “cloud point.” This reduces the flow properties of the fuel, clogging fuel filters and even damage entire fuel systems. At temperatures below cloud point, fuels can reach cold filter plugging point (CFPP), where the fuel becomes solid and loses all its flow properties. Exact cloud and CFPP temperatures depend on the feedstocks used to make biodiesel. Petroleum diesel gels in this same way at lower temperatures.
Because of this, blenders must “winterize” their product for use in cold and freezing temperatures. Biodiesel fuels have higher cloud and gel points than pure diesel fuels, but that does not mean their use is restricted to the warmer months of spring and summer. With proper production and blending procedures, biodiesel can be used as a clean alternative, even when Old Man Winter blows in.
One way to ensure safe, year-long use of biodiesel fuels is to educate yourself on the overall quality and specific cold weather properties of the fuels offered by your distributor. Technical standards exist for biodiesel fuels, which are developed by the American Section of the International for Testing Materials (ASTM). Making sure your supplier offers a product that meets these standards is crucial to limit complications that arise from everyday use, and reduce winter worries.
Pure biodiesel is generally reserved for blending with petroleum diesel. Blends consisting of more than 20% biodiesel show noticeably lower amounts of energy per volumetric unit. Those higher concentrations also gel more easily in cold conditions, so limiting winter use to blends of 20% or less is considered a best practice. Biodiesel fuels created from oils with a lower percentage of saturated fats also have a lower cloud and gel point than those created from oils with a higher percentage of saturated fats. Ohio suppliers are at an advantage, as soybean oil is their major source and contains 16% saturated fat. This relatively low percentage, along with proper blending procedures and use of cloud point additives in the petroleum diesel portion, helps defend against cold flow issues. Ohio customers can confidently rely on biodiesel knowing that colder, western sites such as Yellowstone and Teton National Parks make year-round use of B20 fuel (a 20% biodiesel blend).
Additional tips for successful use of biodiesel during winter months are to store vehicles indoors when able, make necessary adjustments to fuel storage and handling plans, and follow scheduled vehicle maintenance and checkups. See the following link to find your nearest biodiesel fueling station.
Clean Fuels Ohio’s offers direct consultation and guidance to our fleet members regarding use of biodiesel and other alternative fuels. Staff at CFO also can help fleet administrators connect with a variety of long-time and current users that are making biodiesel work today.