Currently, almost every gallon of gasoline contains 10% ethanol made from corn and 90% petroleum gasoline refined from crude oil as a result of the federal Renewable Fuel Standard. (RFS). However, declining gasoline use is intensifying the existing fight between big oil companies and the corn ethanol industry (or Big Corn) over how much of the shrinking transportation fuel pie each gets. The most immediate impact of the RFS wars is to focus attention on corn ethanol and petroleum gasoline at the detriment of second-generation biofuels. These fuels — produced from the inedible parts of plants with much lower greenhouse gas emissions than corn ethanol — can also be blended with gasoline. Adding them to the fuel mix would lessen transportation-caused emissions considerably because they emit vastly less carbon than corn ethanol or petroleum gasoline.While commercialization of second-generation biofuel has been very slow up to now, with only negligible volumes produced in 2017, recent innovations by American companies provide some hope. Today, several firms are producing cellulosic ethanol from corn kernel fiber, which would otherwise not be used productively. o Big Oil, EPA has secretly given compliance exemptions from using ethanol to several large and profitable firms that own small refineries. While EPA has the authority to exempt small refineries that suffer "disproportionate economic hardship" from complying with the statute, it has not demonstrated such hardship in these cases. Continuing these covert exemptions would be a back-door way to reduce the RFS mandate, and a reading of the law suggests it would be illegal. To placate the corn ethanol industry, the White House has proposed to allow year-round sales of gasoline containing 15% ethanol, up from the current 10%. However, because ethanol increases ozone levels, this violates current air quality standards specified in the Clean Air Act. Furthermore, EPA had previously determined that it could not legally make the change.