I have seen the question frequently arise as to whether the ethanol blending mandate is based on rigid numbers (e.g., 9 billion gallons in 2008) or whether it is actually a percentage requirement, and the number is an estimate based on projected gasoline sales. In other words, let's say that hypothetically gasoline sales this year are only half the level of last year. Is the mandate still for 9 billion gallons, or does it drop to 4.5 billion gallons?

Also, a claim was recently made here that refiners are underblending ethanol this year, and are likely to end the year in violation of the mandate. So, I also sought some clarification around this issue. I contacted Peter Gross at the EIA, who seemed to be their expert in this area. He was kind enough to reply, and clarified both issues: