Earlier this year, the EPA
because it has a negative environmental balance of lifecycle greenhouse gas emissions when compared to gasoline obtained from crude oil (read their report here
). As there's rarely an attack without pushback, the Renewable Fuels Association has decided
to interpret that report from their point of view and has found that certain sources of oil do indeed have a worse negative impact than corn ethanol. That is, when lighter and more easily refined crude grades become exhausted, oil will need to be extracted from other sources (e.g., oil sands) and these methods incur greater environmental impact. By comparison, RFA says, corn ethanol looks good.
Of course, we can have a long debate on what to take in account when producing these fuels. Yes, the fuel burned by the tractor that plowed the land where corn was grown can be taken into consideration, as it us under ISO standards. But what about the oil used to produce the tractor itself? How about the balance of cutting some forest to plant sugarcane in Brazil? Not an easy equation, but one that invites more pushback.