ASTM International (previously the American Society for Testing and Materials) continues to refine and improve the specifications for biodiesel and biodiesel blends. The National Biodiesel Board's (NBB) Steve Howell is chairman of the ASTM Biodiesel Task Force and leads the intense efforts to work with original equipment manufacturers and other ASTM members to secure specifications for finished blends of B20 and lower.

"The key to good performance with B20 and lower blends is using biodiesel meeting D 6751 to make the blend," Howell said. "The B100 and blended fuel specifications are being set up so that if you have good biodiesel and good diesel fuel, the blended fuels should meet their specifications."

B5 and lower blends are being incorporated into the traditional petroleum diesel specification, ASTM D 975, while B6 to B20 will be a new, separate stand-alone specification. The B5 specification passed ASTM's Subcommittee E on diesel fuel in December 2006. However, concerns over the possibility of some small fraction of biodiesel exhibiting precipitates above the cloud point must be addressed by a Subcommittee E task force, which was also formed in December. The ballot will then move to the ASTM D02 main committee for final approval. The NBB's Don Scott has worked closely with the National Renewable Energy Laboratory to help provide data to the new ASTM task force.

"The task force is focusing on investigating the phenomenon and developing performance-based measurements for B100 that will indicate acceptable performance of vehicles with B5," Howell said. "We should have more data in June, and the hope is that we will have a set of actions to resolve the issue and be able to move forward with the final B5 approval in December, but it will be dependent upon what the task force comes up with."

At press time, another ballot on the stand-alone B6 to B20 specification was forwarded to ASTM's Subcommittee E for a vote and was expected to be adjudicated at the June meeting. The current version of the B6 to B20 ballot is based on the Engine Manufacturers Association's B20 test specifications. NBB representatives hoped that any negative votes on the B6 to B20 specification could be resolved and the specification would pass Subcommittee E to be ready for the D02 main committee ballot, as soon as the precipitates-above-the-cloud-point matter is resolved in D 6751.