Energy and Greenhouse Gas Emission Impacts of Fuel Ethanol

1
Energy and Greenhouse Gas Emission Impacts of
Fuel Ethanol

• Michael Wang
• Center for Transportation Research
• Argonne National Laboratory
• Presentation at UIUC Sustainable Bioenergy
  Workshop
• April 14, 2006

2
The GREET (Greenhouse gases, Regulated Emissions,
and Energy use in Transportation) Model Includes
Energy and Emissions

• Includes emissions of greenhouse gases
• CO2, CH4, and N2O
• VOC, CO, and NOx as optional GHGs
• Estimates emissions of five criteria pollutants
• Total and urban separately
• VOC, CO, NOx, SOx, and PM10
• Separates energy use into
• All energy sources
• Fossil fuels (petroleum, natural gas, and coal)
• Petroleum
• The GREET model and its documents are available
  at Argonnes GREET website at http//www.greet.anl
  .gov
• The new GREET version 1.7, together with its user
  manual, was released in November 2005

3
U.S., Brazil and China Are Major Ethanol
Consuming Countries

• U.S.
• Corn ethanol
• No.1 consuming country with 4.2 billion gallons
  in 2005
• Brazil
• Sugarcane ethanol
• No.2 consuming country with 4 billion gallons in
  2005
• China
• Corn ethanol
• No.3 consuming country with 340 million gallons
  in 2005

4
Petroleum Refining Is the Key Energy Conversion
Step for Gasoline and Diesel
5
Ethanol WTP Pathways Include Activities from
Fertilizer to Ethanol at Stations
Agro-Chemical Production
Agro-Chemical Transport
Corn Farming
Woody Biomass Farming
Herbaceous Biomass Farming
Corn Transport
Woody Biomass Transport
Herbaceous Biomass Transport
Ethanol Production
Electricity (Cellulosic Ethanol)
Animal Feed (Corn Ethanol)
Transport, Storage, and Distribution of Ethanol
Refueling Stations
6
Accurate Ethanol Energy Analysis Must Account for
Increased Productivity in Farming Over Time
U.S. Corn Output Per Pound of Fertilizer Has
Risen by 70 in The Past 35 Years
Based on historical USDA data results are 3-year
moving averages
7
Improved Technology Has Reduced Energy Use and
Operating Costs in Corn Ethanol Plants
From Argonnes discussions with ethanol plant
designers, USDA data, and other reported data
8
One-Third of Corn Kernel Mass Ends as Animal
Feed (a Co-Product) in Ethanol Plants
9
Accounting for Animal Feed Is a Critical Factor
in Ethanols Lifecycle Analysis
Argonne uses the displacement method, the most
conservative approach.
10
Energy Effects of Fuel Ethanol Depend on the
Type of Energy Being Analyzed
Total Energy
Fossil Energy
Petroleum Energy
Total Btu Spent for One Btu of Gasoline and
Ethanol Available at Fuel Pumps
11
Most Recent Studies Show Positive Net Energy
Balance for Corn Ethanol
Energy balance here is defined as Btu content a
gallon of ethanol minus fossil energy used to
produce a gallon of ethanol
12
Energy in Different Fuels Can Have Very
Different Qualities
13
Comparative Results Between Ethanol and Gasoline
Are More Relevant to Policy Debate
14
Corn EtOH Reduces GHGs by 18-29 While Cellulosic
EtOH Yields 85-86 Reduction, on Per Gallon Basis
of EtOH Used
GHG Emission Reductions Per Gallon of Ethanol to
Displace An Energy-Equivalent Amount of Gasoline
Recent examination by Farrell et al. of lime
application for corn farming may result in 3-4
percentage points lower GHG reduction benefits by
corn ethanol.
15
Debate on Energy Balance Itself May Have Little
Practical Meaning

• Though self evaluation of a fuels energy balance
  is easy to understand, to do so for a fuel in
  isolation could be arbitrary
• All Btus are not created equal. The energy sector
  has been converting low-value Btus into
  high-value Btus, with energy losses
• Society has not made energy choice decisions on
  the basis of energy balance values of individual
  energy products
• Issues of concern, such as petroleum consumption
  and GHG emissions, should be analyzed directly
  for fuels
• A complete, robust way of evaluating a fuels
  effects is to compare the fuel (e.g., ethanol)
  with those to be displaced (e.g., gasoline)

16
Opportunities and Challenges of Near Future U.S.
Corn Ethanol Production

• Opportunities
• Corn yield/acre will continue to increase,
  together with stabilized or reduced N fertilizer
  application
• Ethanol yield/bushel will continue to increase
• Energy use in ethanol plants may be reduced
  further through better engineering, integration
  of ethanol production and animal feedlots
• Gasification of biomass to provide process energy
  for ethanol plants
• Challenges
• Switch from natural gas to coal in ethanol plants
• Potential use of marginal land for additional
  corn production

17
Supply of Grain-Based Ethanol in the U.S. and
China May Be Limited

• In 2005, the U.S. produced 11.1 billion bushels
  of corn 13 was used for ethanol production
• In 2005, the U.S. used 4.2 billion gallons of
  fuel ethanol, equivalent to 2.79 billion gallons
  of gasoline
• In 2004, the U.S. consumed 141.7 billion gallons
  of gasoline and 37.4 billion gallons of on-road
  diesel fuels

18
Conclusions

• Any type of fuel ethanol helps substantially
  reduce fossil energy and petroleum use, relative
  to petroleum gasoline
• Corn-based fuel ethanol achieves moderate
  reductions in GHG emissions
• Cellulosic ethanol can achieve much greater
  energy and GHG benefits