ASTM International has taken a big step forward in the process of creating a new specification that will cover blends of six to 20 percent biodiesel (B6 to B20). The biodiesel blend specification was approved by the ASTM International’s D02 Subcommittee E in December. Major engine companies and petroleum refiners joined the biodiesel industry in voting for passage of this ballot. The ballots will now need final approval from the main committee at the June 2008 ASTM meeting.
The biodiesel industry has known for years that B20 made with in-spec biodiesel is a good quality, reliable fuel, but the majority of original equipment manufacturers (OEMs) view the adoption of a blended fuel specification as a key component for full, universal acceptance of B20. Chrysler has previously announced the company plans to issue formal support for B20 once ASTM has formally approved B20 specifications.
According to the ballot, the biodiesel portion of the B6 to B20 specification must meet the ASTM D6751 standard for pure biodiesel prior to blending, and the finished blend must meet the widest of the specifications for either No. 1 or No. 2 diesel. Parameters to measure acid number and stability were also added to the finished blend specification as an additional assurance of the fuel’s stability over time. In addition, the specifications allow the 90 percent distillation point to be five degrees Celsius higher for the blend.
The subcommittee also passed ballots that would allow the formal incorporation of up to five percent biodiesel into the existing specification for diesel fuel (ASTM D975) and the existing specification for home heating oil (ASTM D396). The biodiesel portion must meet ASTM D6751 prior to blending; the specification limits the biodiesel content to five percent and lower; and the finished specifications remain the same as those currently in place for petrodiesel, with no changes.
Finally, the subcommittee also made refinements to the current standard for pure biodiesel, ASTM D6751. Changes to the B100 blend stock specification were needed to address the potential issue of filter clogging above the cloud point with B20 and lower blends. This also passed Subcommittee E in December. This was critical, as ASTM members voted in December 2006 that finished blends would not be allowed to pass until this issue was addressed at the B100 level.
Renderers Oppose Proposed Quality Standards
The National Renderers Association (NRA) Biofuels Committee coordinated rendering industry response to the proposed ASTM D6751 specification changes to the diesel fuel spec ASTM D975 allowing biodiesel to be blended in at a five percent level. A cold soak filtration test was developed to screen biodiesel for a problem that has appeared in cold weather – formation of sterol glucosides. The problem for animal fats is that they may be problem-free in cold weather and have no sterol glucosides (which is a vegetable oil problem), but test poorly by this procedure.
A number of “no” votes on the cold soak filtration test portion of the proposed changes were submitted by NRA members with justification and supporting data. At the Subcommittee E meeting in December, several comments were made that the data presented was good and made a point, but the committee remained unconvinced and the “no” ballots were voted as non-convincing by an overwhelming majority of the committee. Some believe the current opinion of the subcommittee is that a poorly designed test is preferred to allowing the Environmental Protection Agency (EPA) to set standards, and that a technical correction can be put in place when better knowledge is brought to the subcommittee. The new Energy Independence and Security Act of 2007 signed into law in December authorizes EPA to set blend standards within one year if none are in place. ASTM, with a long history of an unbiased and scientific approach to testing methods, prefers to remain the U.S. authority to set scientific standards and test methods.
It was acknowledged at the meeting that more testing and data collection needs to be done before the issue comes up again at the full committee at the next ASTM meeting in June 2008. Renderers feel some sort of test is necessary, but it needs to work without discriminating against quality biodiesel made from animal fats. They are not alone in that thought.
Bob McCormick and Teresa Allman of the National Renewable Energy Laboratory have committed to working to understand the cause of the filter clogging and ensure that any test is correct and unbiased against any feedstock. Key investigators into the filter clogging issue have indicated that the cold soak test as designed was not correlated with palm oils and certain animal fats whose cold flow points were significantly different than normal lab temperatures, and are working on appropriate laboratory methods for those products. Other companies are also working to determine if there is another measurement or method to correlate the field problem of cold weather filter clogging. Some suspects beyond sterol glucosides have been phosphorus, mono-glucosides, soaps, previously unchecked metals, reduced water contents, just to name a few, and all are being investigated.
Petroleum and OEM representatives indicated they did not know the cause of the field issues with some biodiesel and filter clogging, but that they simply wanted a test to assure the public of trouble-free use of blends in order to comply with new renewal fuel standards.
February 2008 Render