Though the Environmental Protection Agency has already ruled on ethanol-blended gasoline mixtures for 2018, that hasn't stopped ethanol advocates from pushing for a higher 30-percent blend for non-flex-fuel vehicles.

The latest call for ethanol comes from corn-state ethanol refiners, farmers, and an ethanol-producer trade association, all of whom want the EPA to take a good, long look at raising the approved blend for standard "gasoline" from E15 to E30.

Meanwhile, on the other side of the debate, two bills making their way through Congressional committees would cap ethanol blends at E10 for the foreseeable future.

DON'T MISS: Renewable-fuel mandate ruling leaves no one happy: the best compromise?

According to Hemmings Daily, the Renewable Fuel Mandate forced the addition of corn-based and cellulosic ethanol to the nation's fuel supply by mandating minimum biofuel amounts.

The flaw in the bill is that it required set volume goals in gallons, presuming that U.S. consumption of gasoline would rise continuously.

Beginning in 2007, the amount of ethanol added would rise each year, with the ultimate goal of reaching 36 billion gallons of conventional biofuels by 2022.

Pump with multiple ethanol/gasoline blends.

Pump with multiple ethanol/gasoline blends.

In fact, however, gasoline consumption in the U.S. fell steadily starting in 2008 and has only recently begun to rise again from the new, lower levels.

That meant that the volumes of ethanol mandated by the EPA represented a much higher percentage of overall fuel consumption than anticipated by the act's sponsors a decade ago.

For 2018, the EPA has mandated the addition of 15 billion gallons of biofuels to the fuel supply.

READ MORE: EPA to study cutting amount of ethanol in U.S. gasoline

Still, the addition of more biofuels to the overall supply doesn't necessarily mean consumers will see higher ethanol blends at the pumps. Only flex-fuel vehicles, largely full-size trucks and SUVs, can burn mixtures of up to E85—which remains rare nationwide.

E10 gasoline remains the dominant blend, and relatively few gasoline retailers have chosen to install the pricey "blender pumps" required to offer E15 as well as E10, in part because they see no evidence of consumer demand for the fuel.

Retailers are free to offer whatever ethanol blends they choose, however, although only vehicles from 2001 or later are approved to use fuels with an ethanol blend of E15 and lower.

Non-ethanol gasoline pump

Non-ethanol gasoline pump

Some retailers, on the other hand, market E0, or pure gasoline with no ethanol, which is preferred by owners of small engines for marine, power-tool, and recreational uses.

Pro-ethanol groups are campaigning to increase the approved blend amount for non-flex-fuel vehicles to E30, thus stoking demand in their own fuel.

The EPA can approve the higher blends through a waiver program, which it has done twice in the past for E10 and E15.

CHECK OUT: E15 gasoline faces stronger headwinds as more states move to ban it (Mar 2017)

Glacial Lakes Energy, a refiner in South Dakota, says it has sold nearly 2 million gallons of E30 with no adverse effects.

It and a number of ethanol-related business have been lobbying government over the last year to again study higher mixtures, but the EPA hasn't taken any action.

The EPA didn't mention E30 at all in its last report on the Renewable Fuel Mandate.


Follow GreenCarReports on Facebook and Twitter.