Photo: NREL
February 11, 2011
BY Ron Kotrba
Teresa Alleman, a senior chemist at National Renewable Energy Laboratory in Golden, Colo., presented the latest biodiesel quality survey results at the National Biodiesel Conference & Expo this week—and the results are very positive, not only for biodiesel producers who make the fuel, but also for blenders and end-users.
This was the first B20 quality survey conducted by NREL in which the samples were held against ASTM D7467, the B6 to B20 blend spec.
Samples were taken from retail outlets during the December 2009/January 2010 timeframe, and three-fourths of them were obtained from regions NREL deems as colder, while the remaining fraction were taken from warmer regions. Geographic areas with average temperatures below minus 12 degrees Celsius (10.4 degrees Fahrenheit) are considered cold climates, Alleman said, and above that are deemed warmer.
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Tests for accurate biodiesel content in the samples showed 95 percent were blends of B20 or below, and 76 percent were between B6 and B20. Only one sample displayed greater biodiesel content than 20 percent.
NREL also photographed 26 pumps to assess Federal Trade Commission compliance with labeling, and found the vast majority of pumps were labeled correctly, including details down to the black lettering, blue background and font size. A few labels were out of compliance and homemade, but still effectively relayed the message about the fuel blend.
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Acid value tests showed all samples met the D7467 spec, and half of the B20 fuel samples came in at less than half of the specification.
Eighty percent of the B20 samples met the oxidative stability spec, and the warmer climate samples tested tended not to meet the spec as often as those in the colder climates. Sample age, however, was not known.
Most samples tested below 200 parts per million for moisture under the Karl Fischer test method.
Even though there is no cloud point specification, Alleman said the fuel samples displayed that there’s a wide range of cloud point in the field. NREL also did a FAME characterization study of the samples, and found there was a 50/50 split between straight soy biodiesel and multifeedstock biodiesel (a complex mixture of any two or more feedstocks out there).