A life cycle assessment of advanced biofuel production from a hectare of corn
2011
Kauffman, Nathan | Hayes, Dermot James | Brown, Robert
Conventional agricultural life cycle assessments (LCAs) measure greenhouse gas (GHG) emissions for biofuel pathways as the amount of carbon dioxide equivalent emitted per unit of energy provided by the pathway (i.e. gCO₂e/MJ). This measure of GHG emissions, as computed by the Environmental Protection Agency (EPA) is then used to determine the extent to which the corresponding biofuel pathway complies with the GHG emission standards set forth by the Energy Independence and Security Act (EISA) of 2007. Under current legislation, ethanol produced from corn grain is prohibited from qualifying as an advanced biofuel, even if it were to meet the GHG emission standards. This paper proposes a measure of GHG emissions based on a unit of land rather than the energy provided by a biofuel pathway utilizing only one feedstock. A hectare of corn thus provides two feedstocks for the biofuel pathway considered here; corn grain is used for production of ethanol while corn stover is subjected to fast pyrolysis for production of biochar and bio-oil. The bio-oil is then subsequently upgraded to a fuel suitable for use as a drop in fuel in internal combustion engines. A LCA of this pathway is conducted and it is found that such a pathway generates a 52.1% reduction in GHG emissions. This is a reduction that is sufficient to qualify the combined output of a hectare of corn as an advanced biofuel if the current restriction in EISA were removed.
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