As the petroleum industry has become more confident in meeting the ultra-low sulfur diesel (ULSD) sulfur requirement of 15 parts per million maximum, it has started to squeeze every ounce of profit from ULSD operations. This has resulted in changes in the composition of ULSD, which is having unexpected effects with both petro-

diesel alone and with some biodiesel blends. Some petrodiesel alone is exhibiting tank corrosion and internal injector deposits not observed before. And although rare, some petrodiesel blended with biodiesel is exhibiting filter clogging above the cloud point as the temperature gets lower. Since one of the benefits of biodiesel is its ability to be blended seamlessly with petrodiesel, ASTM is considering changes to the existing B100 specification (ASTM D6751) to address even these rare occurrences with petrodiesel/biodiesel blends.

To tackle this issue, the technical expert members of ASTM are proposing a new grade of B100, a No. 1-B grade, with tighter controls on minor components that serve as predictors for the phenomenon. The current specification parameters in D6751 would become a No. 2-B grade of B100. Either grade could be used at any time of the year. The proposed No. 1-B biodiesel would be an option to help insure operation of finished blends down to their cloud point, if blends with No. 2-B exhibit filter clogging above the cloud point.

Engine makers and diesel customers gain confidence from the fact that biodiesel has an ASTM specification (no other alternative for diesel fuel has an ASTM specification at this time) and that the industry is committed to continually improving the existing specs, and therefore the quality of the fuel. This bodes well for biodiesel, the first commercially available advanced biofuel, as a low-cost option for reducing harmful greenhouse gases and meeting the new renewable fuel standard (RFS2) requirements for the use of more than 1 billion gallons of advanced biofuels in 2012.