WASHINGTON -- Small and medium producers of biodiesel have "significant failure rates," while about 90 percent of all tested biodiesel meets specifications, according to the U.S. Department of Energy's 2007 biodiesel quality survey.
To evaluate the quality of biodiesel produced in the U.S., the DOE's National Renewable Energy Laboratory conduct periodic quality surveys to see if the fuel meetings ASTM International D6751 specifications. Biodiesel must meet these specs to be considered a legal fuel and qualify for tax credits.
The samples were tested for properties deemed critical for engine operation: oxidation stability, flash point and alcohol content, cloud point, water and sediment, acid value, and free and total glycerin. They also were analyzed for phosphorus, sodium, potassium, magnesium and calcium, which are poisons to advanced emissions control equipment.