ASTM working group makes progress on biodiesel standard

Although biodiesel has the ASTM International standard of D 6751, its working group has pursued an aggressive technical program over the past 12 months in order to further refine the specification. The ASTM Biodiesel Task Force, chaired by National Biodiesel Board (NBB) Technical Director and Marc-IV President Steve Howell, has been leading the implementation of the research program to ensure that the spec incorporates the most efficient test methods necessary to address all aspects of performance. The task force has been busy balloting changes, with some success for the mainstream growth of the fuel. During the past six months, more than 19 biodiesel-related ballots were issued and voted upon. They have addressed the B100 blend-stock spec, as well as the establishment of blended biodiesel specs.

Perhaps the most important action was the first-ever approval of a stability parameter for the B100 blend stock standard. "Passage of a stability spec in B100 had been the biggest roadblock identified by the engine and vehicle community in order for them to consider stronger endorsement and support for B20," Howell said. "This specification is designed to prevent sediments and gums, which can form as the fuel ages."

Several other updates were made to the B100 blend-stock ASTM specification over the past year, such as:

--Lowering the maximum acid number specification to 0.5 mg KOH/g

--Adding requirements for combined calcium/magnesium and sodium/potassium at a maximum of five parts per million, along with a new method for measuring all four metals with one test

--Allowing direct measurement of methanol for alcohol control

--Allowing the use of faster automated tests as alternates for the manual versions

"Much of this work is behind the scenes, and it is often uninteresting compared to other biodiesel activities making headlines today," Howell said. "However, industry players can rest assured that NBB is on the job, coordinating these extremely important technical efforts for the industry's quality assurance. That helps make all those positive headlines possible."

The efforts mentioned above are part of the process of helping ASTM establish specifications for finished blends up to B20. ASTM D 6751 has been set up so that if B100 meets its spec, petrodiesel meets its spec and normal precautions are taken (cold flow, etc.), then blends of B20 and lower should perform well. This is similar to the way No. 1 and No. 2 diesel fuel is blended. Efforts to formally approve up to B5 in the conventional petrodiesel spec, ASTM D 975, and a new stand-alone spec that will cover finished B6 to B20 blends, have been in the works for over four years.

Both blended fuel specs were balloted again at the subcommittee level in December 2006, and the B5 ballot passed the subcommittee for the first time. More discussion on B6 through B20 was planned for late January, with another re-ballot soon. A ballot of B5 at the main committee level will occur after a new ASTM task force issues recommendations on the potential for precipitates above the cloud point in B100.

With progress being made, Howell feels guardedly optimistic that it is possible to have ASTM-approved blended fuel specifications for B5, and B6 through B20, by the end of 2007.