Sustainable Corn Production Supports Advanced
Biofuel Feedstocks By
Ann Perry November 24, 2009
Researchers worldwide are trying to economically convert cellulosic
biomass such as corn stover into "cellulosic ethanol." But
Agricultural Research Service (ARS)
scientists have found that it might be more cost-effective, energy-efficient
and environmentally sustainable to use corn stover for generating an
energy-rich oil called bio-oil and for making biochar to enrich soils and
Stover is made up of the leaves, husks, cobs and stalks of the corn
plant, and could provide an abundant source of feedstock for cellulosic ethanol
production after the grain is harvested. But removing stover from the field
would leave soil more vulnerable to erosion, deplete plant nutrients and
accelerate the loss of soil organic matter.
Several ARS scientists collaborated with the
National Corn Growers Association to explore
other options for using corn stover as biofuel feedstock. Chemical engineer
Mullen, mechanical engineer
Goldberg and research leader
Hicks all work at the ARS
Regional Research Center in Wyndmoor, Pa. Chemist
Lima, who works at the ARS
Regional Research Center in New Orleans, La.; and soil scientist
Laird, who works at the ARS
Laboratory for Agriculture and the Environment in Ames, Iowa, also
contributed to the study.
The team used fast pyrolysis, which is rapid heating in the absence of
oxygen, to transform corn stover and cobs into bio-oil and bio-char. They found
that the bio-oil captured 70 percent of the total energy input, and the energy
density of the bio-oil was five to 16 times the energy density of the
This suggests it could be more cost-effective to produce bio-oil
through a distributed network of small pyrolyzers and then transport the crude
bio-oil to central refining plants to make "green gasoline," rather than
transporting bulky stover to a large centralized cellulosic ethanol plant.
In addition, about 18 percent of the feedstock was converted into
bio-char, which contains most of the mineral nutrients in the corn residues.
Using biochar as a soil amendment would return those nutrients to the soil,
reduce leaching of other nutrients, help build soil organic matter and
sequester carbon. These benefits would help mitigate the adverse environmental
effects of harvesting stover for fuel production.
These findings were published online in the journal Biomass
This research supports the
U.S. Department of
Agriculture (USDA) priority of developing new sources of bioenergy. ARS is
USDA's principal intramural scientific research agency.