Assuming that each gallon of biodiesel (100 percent methyl ester, B100) requires about 7.5 pounds of feedstock, the mandate for 1.28 billion gallons of biodiesel in 2013 would require about 9.66 billion pounds of feedstock. Some portion of that requirement could be met with animal fats, waste grease, and animal waste and byproducts. Various estimates of that potential have been made. Census Bureau estimates of fats and oils consumption for methyl esters available through July 2011 suggest that total might be near 3 billion pounds per year. The remainder of the feedstock, about 6.66 billion pounds, would be various vegetable oils, primarily soybean oil.

If the total advanced mandate of 2.75 billion gallons in 2013 was met by biodiesel, 1.83 billion gallons (2.75/1.5)of biodiesel would be required. That production would require 13.8 billion pounds of feedstock, of which 10.8 billion would be vegetable oil. Looking further ahead, if the entire advanced mandates in 2014 and 2015 were met with biodiesel, 2.50 billion gallons (3.75/1.5) and 3.67 billion gallons (5.50/1.5) of biodiesel would be required, respectively. This would in turn require 15.9 billion pounds of vegetable oil in 2014 and 24.7 billion pounds in 2015. If biodiesel was also used to meet the shortfall in the renewable biofuels mandate in 2013, 2014, and 2015 due to blend wall limitations on ethanol use, addition vegetable oil requirements would total 2.5, 5.5, and 8.6 billion pounds, respectively.

The dilemma presented by the magnitude of vegetable oil requirements under the scenarios described here is two-fold. First, by 2015 biodiesel production used to meet the advanced biofuels requirement would be nearly equal in size to the current (2012) total annual domestic consumption of vegetable oil in the U.S. of 28 billion pounds. Extremely large increases in vegetable oil crop production or vegetable oil imports would be required if biodiesel were to be used to meet biofuels mandates. For example, if domestic soybean oil was used to meet all of the advanced mandate feedstock requirements in 2015 this would require approximately 2.6 billion bushels of soybeans (28/10.7). Second, the biodiesel requirements would exceed the current capacity to produce biodiesel, estimated at 2.5 billion gallons by the EPA. Not addressed here, is the third issue of the likely economic feasibility of producing such large quantities of biodiesel.

Part of the undifferentiated portion of the advance mandate could be met by other advanced biofuels, which currently would be almost exclusively imported sugar cane ethanol from Brazil. Recently (2010) Brazil produced as much as 6.9 billion gallons of ethanol and at the peak in 2006 the U.S. imported about 730 million gallons of ethanol from Brazil. If we assume Brazilian production could support the 2006 level of exports to the U.S, this source of ethanol could meet up to 730 million gallons of the advanced biofuels mandate. That would be about half of the undifferentiated advanced biofuels requirement in 2013, but only 17 percent in 2015. This magnitude of use would not significantly reduce the requirement for biodiesel and vegetable oils. In addition, this is where the dilemma comes full circle. Import of additional ethanol brings the blend wall issue back into play. If the vast majority of ethanol in the U.S. is still being used in a 10 percent blend, ethanol imports from Brazil would have to replace domestically produced ethanol. To maintain domestic ethanol production, ethanol exports from the U.S. (to all destinations) would have to increase by as much as the increase in ethanol imports to the U.S. from Brazil.


There is a clear and impending collision of biofuels mandates and the reality of the ability to produce and consume biofuels in the U.S. For renewable biofuels (ethanol) the impending collision underscores the importance of implementing E-15. Widespread implementation by 2014, or even 2015, would solve the blend wall problem. However, there are several reasons for being cautious about the likelihood of this actually occurring on a wide scale. Avoiding the collision for advanced biofuels is likely to require not only writing down the cellulosic mandate, but also the total RFS mandate. Otherwise, a new and even larger conflict between food and fuel use of crops is in store due to the huge potential draw on vegetable oil feedstocks. This is a problem that the EPA can solve with the stroke of a pen.