Cellulosic Ethanol A 'Good Environmental Fit' For Corn Growers

With cellulosic ethanol production expected to come on strong in 2014, growers stand to benefit from stover residue removal.

Published on: Dec 6, 2013

On the flatlands of central Iowa, yet another ethanol plant is rising above pitch-black soils. This one is different – only the third commercial-scale cellulosic ethanol plant in the country.

Thousands of large square corn stover bales are already stacked up in fields awaiting conversion into ethanol at the DuPont Cellulosic Ethanol biorefinery near Nevada, Iowa – despite EPA's latest proposal to shrink its national cellulosic ethanol mandate.

EPA's proposed reduction would drop the cellulosic fuel production mandate to just 23 million gallons from 1.75 billion gallons for 2014, as required in the 2007 law. The reason cited: Biomass-based ethanol has failed to grow as expected, according to the proposal.

CORN STOVER ETHANOL ON THE RISE: John Pieper, DuPont director for cellulosics and ethanol development, says corn stover is worth about $30 an acre. "But the greatest value to farmers may be in stalk residue removal from continuous corn."
CORN STOVER ETHANOL ON THE RISE: John Pieper, DuPont director for cellulosics and ethanol development, says corn stover is worth about $30 an acre. "But the greatest value to farmers may be in stalk residue removal from continuous corn."

But hold on. Cellulosic ethanol is moving out the pilot project stage – big time. Project Liberty at Emmetsburg, Iowa, is gearing up to fuel its 20-million-gallon cellulosic ethanol plant this year. The Quad County Corn Processors' add-on cellulosic facility at Galva, Iowa, will add another 2 million gallons to the cellulosic tank.

DuPont's $228-million biorefinery is expected to be completed by summer, says John Pieper, DuPont's director for cellulosics and ethanol development. It'll have a 30-million-gallon capacity.

"Our plant will move forward despite this latest proposal from EPA," confirms Wendy Rosen, global public affairs lead for DuPont Industrial Biosciences. "DuPont remains committed to innovation in renewable fuels. Our concerns are with the second wave of plants yet to be built and how this proposal impacts the investment community and their decision making down the road." 

Will cellulosics change corn?

The Quad County cellulosic process converts corn kernel fiber to ethanol. Project Liberty and DuPont's biorefineries will convert stover biomass to ethanol. And, stover harvest and transportation costs involved are not incidental.

So will cellulosics bring changes in corn plant genetics? "Remember, corn grain is the dog," responds Pieper. "Corn stover is the tail. The first conversion is from a cellulose molecule to sugars, then fermentation of sugars to ethanol and other products."

Stover harvest relieves plant breeders of the need to minimize stover relative to grain. With anything more than two years of continuous corn, this is something farmers want, he explains.

"Stover residues are at problematic levels. Now, we can let the above ground biomass remain equal to grain mass in the core Corn Belt, and just keep breeding for additional grain with resulting additional biomass."

DuPont researchers are working to understand cellulose and hemicellulose in corn plants. If significant differences occur, they may be variably advantageous to ethanol production, says Pieper.

"If so, we could characterize hybrids for 'good' cellulose and choose to contract/harvest fields where hybrids with 'good' cellulose were planted because of their grain-producing characteristics.

"Someday, it may be possible and profitable to breed for both grain production and cellulose quality." For now though, that's a stretch, he adds.