Quality analysis of wintertime B6-B20 biodiesel blend samples collected in the United States

A survey of the quality of biodiesel blends in the United States was conducted in the winter of 2009-2010. Forty samples were collected in the study; two-thirds of the samples collected were from areas with a 10th percentile minimum ambient temperature below - 12 degrees C. Fuel properties were measured and compared to the relevant ASTM D7467-09 specification properties. The B6-B20 study shows increased compliance with the blend level requirements to 72.5% of samples tested, with a cold state average biodiesel content of 12% and a warm state average biodiesel content of 19%. The decreased biodiesel content in cold states is likely to due to deliberate reductions to meet the cloud point expectations. Continuing problems were noted with induction period stability for B6-B20 blends, with a failure rate of 24%. Samples collected from cold weather states had a failure rate of only 18%, likely because of the reduced biodiesel content; the failure rate from warm weather states rose to 57%. Samples failed the induction period stability specification before the acid value increased to the point of failure and no acid value failures were recorded. No failures were observed water and sediment. A single failure was noted for flash point, likely due to external contamination during fuel handling. Cloud point and cold filter plugging points are reported. (C) 2011 Elsevier B.V. All rights reserved.