Citing biofuel production constraints and an ongoing decrease in demand for gasoline usage, the U.S. EPA is proposing in today's Federal Register to lower the amount of renewable fuel that refiners must blend into gasoline and diesel in calendar year 2014. If approved, it would be the first time the EPA required an amount of renewable fuel less than what is called for in the Energy Independence and Security Act (EISA) of 2007, which led to creation of the Renewable Fuel Standard that establishes annual overall volume requirements for total renewable fuel as well as annual volume requirements for specific types of renewable fuel. The statutory overall volume requirement for 2014 is 18.15 billion gal, but EPA is proposing to lower the requirement to 15.21 billion gal. The EISA orders the EPA to ratify the statutory volume requirements every year, or to lower them if warranted by market conditions. To achieve the 2014 statutory level of 18.15 billion gal, refiners would have to produce gasoline that exceeds 10% ethanol content (E10). That is the level for which engines in most light vehicles are engineered. Although the EPA has approved (but not mandated) the use of E15 for use in newer vehicles (MY2001 and newer), automakers do not warranty all of their newer models to that level; this is one of the EPA’s considerations in its proposal to lower the requirement for 2014, as is the agency's expectation that improved vehicle fuel efficiency will continue to diminish demand for gasoline. The public may comment on the EPA proposal (and view already-submitted comments) here.