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Abstract
The use of fuel ethanol in the United States has increased
from fewer than 200 million gallons (gal) at the beginning
of the US fuel ethanol program in 1980 to 6.5 billion gal in
2007. The recent federally adopted Energy Independence and
Security Act of 2007 established the goal of 36 billion gal of
biofuel use in the United States by 2022, of which 15 billion
gal will be corn-based ethanol. In addition, the promotion of
low-carbon fuel standards (LCFS) by California and several
other states could help increased use of ethanol, especially
cellulosic ethanol.
In the United States, corn ethanol is produced through the
fermentation of corn in dry and wet milling plants, most of
which are located in the Midwest. In 2006, about 82% of the
total US fuel ethanol was produced from dry milling plants,
and the remaining 18% from wet milling plants (Renewable
Fuels Association, 2007). Ethanol can be produced from cellulosic
biomass through fermentation of cellulose and semicellulose.
The US Department of Energy (DOE) has been undertaking
extensive research and development (R&D) efforts
for cellulosic ethanol technologies.
Since 1997, Argonne National Laboratory has been evaluating
the energy and emission effects of fuel ethanol relative
to those of petroleum gasoline. In 1997, Argonne National
Laboratory published its findings from an ethanol analysis
conducted for the State of Illinois (Wang et al., 1997). With
DOE support, Argonne National Laboratory has continued
its efforts to analyze the effects of fuel ethanol (Wang et al.,
1999a,b; Wang et al., 2003; Wu et al., 2005; and Wu et al.,
2006).
As fuel ethanol production and usage in the United States
have rapidly expanded in the past several years, corn ethanol
plant technologies have been evolving. In addition, while
corn yield per acre continues to increase, concerns have been
raised that increased corn farming could result in switches
in crop farming in the United States and potential land use
changes in other countries. These factors together could cause
different energy and greenhouse gas (GHG) emission results
for corn ethanol. This chapter presents Argonne National
Laboratory’s updated energy and GHG emission results for
fuel ethanol.