The U.S. is at the “blending wall” saturation point for ethanol use according to a new Purdue University study. The cause is lack of infrastructure to meet the federal mandate for renewable fuel use with ethanol, but the country could still meet the standard with significant increases in next-generation biofuels and cellulosic fuels.

Wally Tyner, the James and Lois Ackerman Professor of Agricultural Economics, and co-authors Frank Dooley, a Purdue professor of agricultural economics, and Daniela Viteri, a former Purdue graduate student, used U.S. Department of Energy and Environmental Protection Agency data to determine that without new technology or a significant increase in infrastructure, the country will not be able to consume more ethanol than is being currently produced.

This is not new news to an ethanol industry that has been struggling to overcome the blend wall hurdles for years. In fact, the E15 waiver, allowing conventional vehicles and light duty trucks to use 15 percent ethanol, is just one step, of many, to push the country in the right direction of overcoming the blend wall. Last year RFS required approximately 13 billion gallons of renewable fuel, the amount that Tyner predicts is the threshold for U.S. infrastructure and consumption ability. The RFS number for this year is even higher at 13.95 billion for ethanol.

“You can’t get there with ethanol,” said Tyner, whose findings were published in the December issue of the American Journal of Agricultural Economics.

Some of the “blend wall problems” include lack of flex-fuel vehicles (FFVS) that can use higher blends of ethanol up to E85 as well as not enough stations offering these same higher blends of ethanol. Then once you get the stations, Tyner said there is no way to distribute it. “We would need to install about 2,000 pumps per year through 2022 to do it. “You’re not going to go from 100 per year to 2,000 per year overnight. It’s just not going to happen.”

And then there’s the price issue. Even if the fuel were readily available, E85 would have to be priced right because of the lower mileage. For example, if gasoline were $3 per gallon, E85 would have to be $2.34 per gallon to break even on mileage.

So one way to meet the standards with current limitations are advances in the production of thermo-chemical biofuels, which are created by using heat to chemically alter biomass and create fuels. These fuels are also known as “drop-in fuels” because there is no infrastructure changes needed to blend the fuel, such as is the case with ethanol.

Tyner concluded, “Producing the hydrocarbons directly doesn’t have the infrastructure problems of ethanol, and there is no blend wall because you’re producing gasoline. If that comes on and works, then we get there. There is significant potential to produce drop-in hydrocarbons from cellulosic feedstocks.”