Biofuels and Ethanol
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ETHANOL (ethyl alcohol) is produced by
distillation of fermented simple sugars in
grains and other plant materials, called
biomass. In U.S. about 90% of ethanol
produced from corn. Used as gasoline
extender, octane enhancer and oxygenate.
Feedstocks: Grain, Cellulose
Cellulose sources? Corn, prairie grasses,
switchgrass, garbage, etc.
Debate Concerning Benefits Continues
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Energy independence
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Carbon/GHG gains?
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Food prices: what are the costs of
increased biofuel usage?
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Other environmental effects? Water
quality, habitat
Rapid Expansion of Ethanol
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U.S. production:
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Corn:
in 2007 (NASS)
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7 billion gallons of ethanol today,
2 billion gallons in 2002
Acreage, 78 mil acres in 2006, 90 mil
Prices, historically $2.5-$3/bushel,
over $5 now
139 in production, 62 under construction
Biorefineries:
(RFA, Jan. 2008)
Energy Bill:
mandates 36 gallons from biofuels by
2022, 20 billion from advanced
biofuels (EISA)
Some Key Policy Drivers of Economics
Behind Ethanol Expansion
1975
Lead phase-out begins
Ethanol becomes attractive as octane
booster
1978
Energy Tax Act
A $0.40 subsidy per gallon of ethanol
blended into gasoline introduced
19801984
Energy Security Act, Crude
Windfall Tax Act, Surface
Transportation Act, Tax Reform
Act
Insured loans for small ethanol
producers, tariffs on foreign produced
ethanol, ethanol subsidy increased to
$0.50 and then $.60
1992
Clean Air Act Amendments
Mandated oxygenates in many locations,
MTBEs major oxygenate in use
19852003
Various Acts
Subsidy reduced gradually to
$0.52/gallon
Various states banned MTBE’s
2005
Energy Policy Act
Phased out MTBEs as oxygenate
thereby increasing demand for ethanol
2007
Energy Bill
Biofuels mandate for 36 billion gallons by
2022
U.S. Ethanol Biorefinery Locations
Carbon/ GHG debate
(http://www.hybridcars.com/ethanol/benefits-drawbacks.html)
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One might expect that by using E85, net carbon dioxide emissions would be almost zero.
The crops used to make the ethanol absorb CO2 from the atmosphere during their growth,
then this CO2 is put back into the atmosphere when the ethanol is burned in an automobile
engine. But, this ignores other GHG emissions in production. Modern farming relies heavily
on diesel-powered equipment that emits greenhouse gases. Distilling ethanol is also
energy-intensive process and uses electricity from coal.
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University of California at Berkeley researchers examined six major studies of ethanol
production and concluded that using ethanol made from corn instead of gasoline would
lead to a moderate 13 percent reduction in greenhouse emissions.
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More dramatic reductions are possible if technology advances make it economical to
make ethanol from cellulosic materials such as switchgrass. Using cellulosic ethanol,
they project, could result in 88 percent less greenhouse gas emissions.
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The UC Berkeley study contradicts a common criticism of ethanol: that it takes more
energy to produce it than it delivers as a motor fuel. The study concludes that ethanol
made from corn does indeed have a positive “net energy balance,”
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Pimental: argues net energy balance negative.
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Land use changes: Recent SCIENCE papers
Converting forest and grassland to cropland adds previously unforeseen
greenhouse gas emissions to the cost of biofuels, new study says
WASHINGTON (February 7, 2008) - A study published today by Science magazine finds that
biofuels that use cropland are likely to increase greenhouse gases because previous
analyses of biofuels ignored a crucial factor - the use of land.
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Most prior studies have found that substituting biofuels for gasoline will reduce
GHGs. These analyses have failed to count the carbon emissions that occur as farmers
worldwide respond to higher prices and convert forest and grassland to new cropland to
replace the grain (or cropland) diverted to biofuels.
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Using a worldwide agricultural model to account for land use change, the new study found
that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse
emissions over 30 years and increases greenhouse gasses for 167 years. Biofuels from
switchgrass, if grown on U.S. corn lands, increase emissions by 50%.
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A separate paper released by two other authors finds that biodiesel from soybeans has
similar effects as corn ethanol.
Authors: Tim Searchinger, GMF transatlantic fellow and a visiting research scholar
Princeton, Ralph Heimlich, R.A. Houghton, Fengxia Dong, Amani Elobeid, Jacinto Fabiosa,
Simla Tokgoz, Dermot Hayes, and Tun-Hsiang Yu, Iowa State University, the Woods Hole
Research Center, and Agricultural Conservation Economics.