Researchers around the world are trying to economically convert cellulosic biomass such as corn stover into "cellulosic ethanol." But Agricultural Research Service 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 sequester carbon.
The research, under-written by the National Corn Growers Association, 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. Researchers found that the bio-oil captured 70% of the total energy input, and the energy density of the bio-oil was five to 16 times the energy density of the feedstock.
Also, the research indicates that about 18% 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.