The idea is simple: Replace refined hydrocarbons yanked deep out of the earth with vehicle fuel derived from crops.
The ongoing politics of ethanol remain anything but simple.
The latest salvo sally in the ethanol wars was fired by two U.S. senators from agricultural states, Amy Klobuchar [D-MN] and Chuck Grassley [R-IA].
They requested that the Federal Trade Commission look into "reports of oil companies pressing independent gas stations to sell premium gasoline in addition to regular gasoline," which they say they've heard from constituents.
The story was reported by The Wall Street Journal.
Premium precludes ethanol
Most gasoline stations currently have only two tanks, and in order to sell E15--or gasoline with 15 percent ethanol in it--one of those tanks must be used for ethanol, the other for gasoline.
Then the stations will install new "blender pumps" that can adjust the delivered mixture among E10, which can be used in all cars built since 1990, and E15.
But if they're required to sell premium gasoline in addition to regular, there will be no place for the ethanol to go.
Billions of gallons by 2022
And that would hurt the domestic industry, which produces all its ethanol refined from corn--the least efficient method for refining the alcohol fuel.
It would also impede U.S. fuel refiners' ability to meet the increasingly steep mandates from Congress that specifies how much renewable fuel must be used in vehicle fuel.
The U.S. is required to use 36 billion gallons of ethanol and other renewable fuels by 2022, under the terms of the 2007 Energy Independence and Security Act passed by Congress in 2007.
E15 infographic from SmarterFuelFuture.org
Most gas stations are in no hurry to install the new and expensive blender pumps that can switch between E10 and E15.
Today, fewer than 100 stations in the country offer E15, which means you don't have to worry about E15 for a while to come.
The gasoline at your local station today may vary from E0 (which is rare) to E10 (which is increasingly common). Blends vary a lot by state and region.
Cars from 2001 or later
Back in January 2011, the EPA approved E15 for use in all cars built in 2001 or later.
But there remains much controversy over whether its frequent use may damage engines that were never designed with the fuel in mind.
The powerful AAA came out forcefully against E15 last December, for instance, and it continues to lobby on the issue.
"E15 is the most tested fuel, ever," countered advocacy group Fuels America in March, "and the autoindustry [has] failed to provide a single example of problems with drivability during the DOE's testing process."
Not for all new cars
Despite EPA approval, E15 is not approved for use in at least some new cars.
The gas cap of a 2013 Ford C-Max Hybrid we recently tested had an "E15" logo on it, but Chrysler has not certified its cars as E15-ready.
And the politics of ethanol remain as muddy as ever.
The most interesting question may be whether Congress will roll back the increasingly onerous ethanol portion of the renewable fuels mandate.