Transcript Does it take more energy to make ethanol than is contained

Biofuels
Why are biofuels attractive?
• Energy security: locally produced, wider
availability, “grow your own oil”
• Climate change mitigation: one of the few lowcarbon options for the transport sector
• Lower emissions of various harmful pollutants
(e.g., sulfur)
• Liquid fuels: conducive to existing infrastructure,
storage, distribution
– Bioethanol: cars, light trucks, motorcycles
– Biodiesel: commercial vehicles, buses, pumps, isolated
electricity generation
Biofuel production
• Ethanol
– Sugarcane (Australia, Brazil, China, Colombia, Ethiopia, India,
Thailand), sugar beets (EU)
– Maize / Corn (US, China)
– Wheat (Canada, EU)
– Cassava (Thailand)
– Biomass wastes (cellulose): forest products (Canada), wood
wastes, agricultural residues—maize stover, sugarcane trash
– Energy crops—switch grass, hybrid poplar, willow
• Biodiesel
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–
–
–
–
Rapeseed (EU)
Soybeans (US)
Palm oil (Malaysia)
Coconut oil (Philippines)
Plants growing on ‘marginal’ land—Jatropha, Karanja (India)
USDA, July 2006
Greenhouse Gases:
• We burn fossil fuel (coal, oil = fossilized
plants and microscopic algae) MUCH faster
than it is formed - Middle East oil: ~ 110
million years old; US coal: ~ 320 million
years old.
• CO2 + H2O -> CH2O + O2 (photosynthesis);
reverse reaction-burning, decay respiration
• Biofuels: every year ‘burn as we grow’ crops pick up CO2 in photosynthesis, we put
it back by burning -> no net effect on
concentration of greenhouse gases
Things to consider:
• Alternative fuel: what are its TOTAL ‘costs’?
– Example: hydrogen-powered cars: what does it cost
(energy, environmental) to make the hydrogen?
• Biofuels: energy costs of growing include
watering, fertilizer production, transport of
fertilizer and crop, costs of seed grain, cost of
government subsidies, environmental pollution
clean-up, income from byproducts
• Other factors: job creation, competition with
food production, environmental pollution
through fertilizer use, and so on
Does it take more energy to make
ethanol than is contained in the
ethanol?
SIMPLIFIED
1980: yes
1990: probably not
2005: no
the ethanol industry, in terms of energy
use per gallon of ethanol produced, has
become much more efficient over the
years, as has the farmer, in terms of
energy use per bushel of corn grown
Efficiency:
1. Yield of ethanol per acre
2. Net energy yield (ratio of energy in / energy out)
3. Expenses as compared to that of gasoline
derived from oil, combined with miles/gallon
(cars need ~ 30% more ethanol than ‘normal’
gas per mile driven)
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1 acre sugar beets: ~ 720 gallons
1 acre sugarcane: 695 -720 gallons of ethanol
1 acre of corn: 350-420 gallons of ethanol
1 acre of sorghum: 172 gallons of ethanol
Ethanol yield per acre per year, sugar
crops and corn
1000
900
800
Gallons per acre
700
600
500
400
300
200
100
0
1992
Louisiana
1993
1994
Hawaii
USDA, July 2006
1995
1996
1997
Florida
1998
1999
2000
2001
Corn, US average
2002
2003
2004
Sugarbeet
Energy ratios:
• Corn to ethanol: ~1.3 (mean current techniques)
to ~ 1.7 (best present techniques)
• Cellulose ethanol: use enzymes to digest
cellulose) - not yet fully functional.
Estimated: ~3-6
• Sugar cane - sugar beets: ~6-8 (including energy
generated through byproduct burning)
• Difference in fermentation processes of starch
(in corn) and sucrose (in sugar crops): higher
efficiency of sugar
COSTS
0.10
0
0.00
Source:Worldbank
$ per liter of gasoline
100
Jan-06
0.20
Jan-04
200
Jan-02
0.30
Jan-00
300
Jan-98
0.40
Jan-96
400
Jan-94
0.50
Jan-92
500
Jan-90
$ per ton of sugar
World raw sugar vs. gasoline price
Sugar
Gasoline
Rotterdam unleaded
regular gasoline
4Q 2005 US dollars
COSTS
Brazil: world’s lowest-cost sugar producer
• Favorable climate, plentiful land, good soil, and abundant
rainfall in Center-South (cane cultivation water intensive)
• Use of bagasse for plant energy use and surplus
electricity sales
• Between 1975-2000, sugarcane yield per hectare
increased by 33%, sugar content of cane 8%, ethanol
yield from sugar 14%, fermentation productivity 150%
• Modern sugar production and processing and high level
of managerial skills
– More than 500 commercial varieties of cane (each
plant processes around 15 varieties)
– Hybrid sugar mill/distillery complexes
– Planting, harvesting, and plant operations
computerized
Source: USDA 2002
Brazilian
ethanol is
cheapest
Sugarcane-ethanol:
Advantages
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Higher ethanol yield per acre
Lower energy costs
Higher net energy balance
Bagasse is used for production of
steam & power
• Could received 2.5 credits for every
gallon
• Lower Volatile Organic C emissions
Sugarcane-ethanol:
Disadvantages
(production within US)
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•
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Higher feedstock costs
Higher cane transportation costs
Higher processing costs
Higher labor use and labor costs
Higher expenses for repairs,
maintenance, and parts
• Higher expenses for general and
administration
Source: Brazilian Government
Source: Brazilian Government
Source: Brazilian Government
Prospects
for
biofuels
Near term
• Ethanol from sugarcane: best overall chance of commercial
viability
• Biofuel trade liberalization beneficial to all consumers
• Biodiesel remains expensive relative to world oil prices
Medium term
• Fall in production costs
• New feedstocks
• Growing trade
Long term
• Commercialization of cellulosic ethanol: widespread
availability, abundance, and significant lifecycle GreenHouse
Gas emission reduction potential
• Higher oil prices favoring biofuel economics
Source:Worldbank
In Summary:
• Significant use of biofuel-ethanol will reduce
emissions of greenhouse gases significantly
• Corn ethanol production IS energy efficient
• Sugar-crop ethanol production (within US) is
more efficient than corn ethanol production
(BUT: climate, water availability, costs)
• Import of ethanol from Brazil would lower
costs for consumers in the US if sugar tariffs
are abandoned/ lowered (globalization) - no
benefits for US farmers
• Further research is needed to investigate
production of cellulose - ethanol (bacterial
enzyme action) and other compounds
(butanol)