Fiber Frustration: The U.S. EPA Hasn’t Approved a Corn Fiber Pathway in More than Four Years

by Lisa Gibson (Ethanol Producer Magazine) The stalled U.S. EPA approval of corn kernel fiber-to-ethanol pathways could be having a $1 billion impact on a 15-billion-gallon-per-year ethanol industry, says Jim Ramm, director of engineering for EcoEngineers. That’s assuming 3% of overall production could be from fiber and a $2 premium. It’s worst-case scenario, yes, but it’s realistic, nonetheless.

EPA approved its last fiber-to-ethanol pathway in December of 2017. At that time, EPA, led by Administrator Scott Pruitt, outlined concerns around the accuracy in measuring the cellulosic portion of ethanol production. The slammed door has forced ethanol producers to distribute their cellulosic volumes to California or Oregon markets (where fuel standards recognize the pathways), and technology developers to overcome the volume measurement challenge.

EPA’s outdated GREET model is the problem, says Nick Bowdish, president of Siouxland Ethanol LLC in Jackson, Nebraska, and Elite Octane LLC in Atlantic, Iowa. Both plants have corn fiber capabilities recognized in California. “GREET is one of many items the EPA can take action on right now.”

The current methodology uses acid hydrolysis to compare a batch of starch glucans to a batch of both starch and cellulose glucans, thereby estimating overall cellulose glucans. So, a poor starch glucan measurement results in an inaccurate cellulose measurement....

After more than a year of research, Sluiter (Justin Sluiter, a cellulose carbohydrate chemist at the National Renewable Energy Laboratory) released a publication earlier this year, “Direct determination of cellulose glucan content in starch-containing samples,” outlining a new measurement method that removes compounding errors of the two-measurement methods, according to his paper. But the new method does overestimate cellulose when yeast bodies are present, he adds. “I did not have an assay available to measure yeast body glucans accurately.”

Ramm shares the frustration. “The idea is the kernel fiber feedstock that enters the front end of the plant, that fiber is like the skin on the kernel that sticks to your teeth,” Ramm says. “That fiber just passes through the plant. It even passes through a cow. Here we have this low-value feedstock that we can turn into really high-value ethanol, really low-carbon ethanol and also increase the protein in the feed. It’s really got tremendous ties to what the economy is calling for now: Higher-protein feed and lower- and lower-carbon ethanol.”

The economics have always been the spread between the value of D6 and D3 RINs, plus the second-generation tax credit, Bowdish says. “And so, for each plant, whether 50 or 150 MMgy, it’s millions of dollars per year. And more importantly, it’s a solution that could be lowering GHG emissions today, that policy hurdles continue to get in the way of. READ MORE