The biodiesel industry began as a potential value-added market for excess soybean oil. Transesterification of soybean oil into fatty acid methyl esters proved successful and a renewable fuel was born. Not limited to soybean oil, the biodiesel market embraced any fat or oil that could be esterified and meet the necessary quality. Although no ASTM International specification existed at that time, a section in EPAct was amended to allow fleets to use B20 to meet their annual requirements. With the increased importance of biodiesel as a low-carbon transportation fuel, the National Renewable Energy Laboratory (NREL) undertook an extensive program to periodically evaluate biodiesel quality. The so-called blender’s tax credit (BTC) was first enacted for biodiesel blending in 2004. NREL’s first biodiesel quality study in 2005 found 85% of the samples met the ASTM D6751 specification limits. By 2006, only 40% of the samples met the specification. A marked improvement was found by 2007, where nearly 90% met the specification. At the same time, the industry was dealing with other fit-for-purpose issues such as the formation of precipitates above the cloud point. Fundamental research in this area led to further modifications and improvements to the specification. NREL also periodically evaluated the quality of biodiesel blends. Prior to the approval of the B6-B20 specification, ASTM D7467, NREL conducted a blend survey, showing a variety of biodiesel blend levels and quality at the retail pump. Concerns about cold weather operability were paramount in a wintertime survey of B6-B20 in 2011. Results showed reductions in biodiesel content in colder states and notable differences in cloud point, likely to mitigate operability issues. On-going quality surveys show the biodiesel industry consistently meets the quality specifications as the market continues to expand.

U.S. biodiesel quality: From a drop in the bucket to three billion gallons

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.