335
ethanol and overtook Brazil as the world’s largest producer. The surge in corn ethanol production in the United States was accompanied by an increasingly heated
debate about its energy and GHG benefi ts. A growing number of so-called fuel
cycle or well-to-wheel studies became available with a wide range of contradictory
fi ndings. Fuel cycle or well-to-wheel analyses are essentially life cycle assessments
(LCAs) of fuels, even though many of the early studies were from researchers outside of the LCA community and without reference to existing LCA standards.
Studies by Patzek and Pimentel received particular media attention as they found
that, over its life cycle, corn ethanol requires more fossil energy inputs than it has
calorifi c value and emits more GHG s than gasoline. Studies from other research
groups, however, concluded that cumulative fossil energy demand and life cycle
GHG emissions of corn ethanol are substantially lower than those of gasoline. A
meta-analysis intent on settling the controversy was probably one of the fi rst LCAs
published in the journal Science , even though it never mentions the term LCA
(Farrell et al. 2006 ). Unsurprisingly, the study found that the wide range in results
was due to differences in inventory data, system boundaries, and coproduct allocation. It concluded that the GHG savings of corn ethanol are moderate but those of
cellulosic ethanol substantial. Unfortunately, producing cellulosic ethanol, also
called second-generation biofuel, is much more diffi cult than starch- and sugarbased ethanol, since it is very hard to break down the lignocellulosic feedstock in an
economically viable way. So hard, in fact that the US Environmental Protection
Agency (EPA) retroactively reduced the 2013 RFS target volume for cellulosic ethanol from 1 billion gallons to 810,185 gallons ( EPA 2014 a).
The environmental reputation of biofuels received its next challenge in 2008,
when two studies in the same issue of Science reported their fi ndings on the GHG
implications of land use change ( LUC ) (Fargione et al. 2008 ; Searchinger et al.
2008 ). Fargione et al. found that clearing land for fuel crop production creates a
signifi cant “carbon debt” and that biofuels require 17 to 420 years to generate GHG
savings of the same size. Searchinger et al. argued that using feedstock from existing fi elds does not avoid this issue since it induces indirect land use change (iLUC)
by removing the crop from its prior market. For example, corn used for ethanol is
now missing as animal feed, which causes land conversion for new corn production
elsewhere. Searchinger et al. conclude that corn and cellulosic ethanol have higher
GHG emissions than gasoline when iLUC is included. Naturally, these strong fi ndings were contested by many, including biofuel associations and the US Department
of Energy. California’s Low Carbon Fuel Standard (LCFS) and the new RFS include
GHG emissions from iLUC but with confl icting results. The controversy about
LUC and iLUC continues. Both effects are prime examples of consequential LCA
and thus question the usefulness of attributional LCA for environmental decision
making (Plevin et al. 2014 ). It is interesting to note that none of the original LUC
and iLUC researchers came from the industrial ecology or LCA communities.
The next twist in the biofuel saga came the following year with two more Science
publications. The fi rst pointed out that turning fuel crops into electricity for battery
electric vehicles (BEVs) rather than biofuels for ICVs would roughly double cropto- wheel conversion effi ciency (Ohlrogge et al. 2009 ). The second showed how this
18 The Industrial Ecology of the Automobile
ethanol and overtook Brazil as the world’s largest producer. The surge in corn ethanol production in the United States was accompanied by an increasingly heated
debate about its energy and GHG benefi ts. A growing number of so-called fuel
cycle or well-to-wheel studies became available with a wide range of contradictory
fi ndings. Fuel cycle or well-to-wheel analyses are essentially life cycle assessments
(LCAs) of fuels, even though many of the early studies were from researchers outside of the LCA community and without reference to existing LCA standards.
Studies by Patzek and Pimentel received particular media attention as they found
that, over its life cycle, corn ethanol requires more fossil energy inputs than it has
calorifi c value and emits more GHG s than gasoline. Studies from other research
groups, however, concluded that cumulative fossil energy demand and life cycle
GHG emissions of corn ethanol are substantially lower than those of gasoline. A
meta-analysis intent on settling the controversy was probably one of the fi rst LCAs
published in the journal Science , even though it never mentions the term LCA
(Farrell et al. 2006 ). Unsurprisingly, the study found that the wide range in results
was due to differences in inventory data, system boundaries, and coproduct allocation. It concluded that the GHG savings of corn ethanol are moderate but those of
cellulosic ethanol substantial. Unfortunately, producing cellulosic ethanol, also
called second-generation biofuel, is much more diffi cult than starch- and sugarbased ethanol, since it is very hard to break down the lignocellulosic feedstock in an
economically viable way. So hard, in fact that the US Environmental Protection
Agency (EPA) retroactively reduced the 2013 RFS target volume for cellulosic ethanol from 1 billion gallons to 810,185 gallons ( EPA 2014 a).
The environmental reputation of biofuels received its next challenge in 2008,
when two studies in the same issue of Science reported their fi ndings on the GHG
implications of land use change ( LUC ) (Fargione et al. 2008 ; Searchinger et al.
2008 ). Fargione et al. found that clearing land for fuel crop production creates a
signifi cant “carbon debt” and that biofuels require 17 to 420 years to generate GHG
savings of the same size. Searchinger et al. argued that using feedstock from existing fi elds does not avoid this issue since it induces indirect land use change (iLUC)
by removing the crop from its prior market. For example, corn used for ethanol is
now missing as animal feed, which causes land conversion for new corn production
elsewhere. Searchinger et al. conclude that corn and cellulosic ethanol have higher
GHG emissions than gasoline when iLUC is included. Naturally, these strong fi ndings were contested by many, including biofuel associations and the US Department
of Energy. California’s Low Carbon Fuel Standard (LCFS) and the new RFS include
GHG emissions from iLUC but with confl icting results. The controversy about
LUC and iLUC continues. Both effects are prime examples of consequential LCA
and thus question the usefulness of attributional LCA for environmental decision
making (Plevin et al. 2014 ). It is interesting to note that none of the original LUC
and iLUC researchers came from the industrial ecology or LCA communities.
The next twist in the biofuel saga came the following year with two more Science
publications. The fi rst pointed out that turning fuel crops into electricity for battery
electric vehicles (BEVs) rather than biofuels for ICVs would roughly double cropto- wheel conversion effi ciency (Ohlrogge et al. 2009 ). The second showed how this
18 The Industrial Ecology of the Automobile