Energy and Greenhouse Gas Emission Impacts of Fuel Ethanol

							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

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 Argonne’s GREET website at http://www.greet.anl.gov

 The new GREET version 1.7, together with its user manual, was released in November 2005

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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

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Petroleum Refining Is the Key Energy Conversion Step for Gasoline and Diesel
Petroleum Recovery (97.7%) NG to MeOH Corn

Petroleum Transportation and Storage (99%)

MTBE or EtOH for Gasoline

Petroleum Refining to Gasoline (84.5-86%, Depending on Oxygenates and Reformulation) and Low-S Diesel (87%)
Transportation, Storage, and Distribution of Gasoline (99.5%)

Gasoline and Diesel at Refueling Station
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Ethanol WTP Pathways Include Activities from Fertilizer to Ethanol at Stations
Agro-Chemical Production Agro-Chemical Transport Corn Farming Corn Transport

Woody Biomass Farming
Woody Biomass Transport

Herbaceous Biomass Farming Herbaceous Biomass Transport

Animal Feed (Corn Ethanol)

Ethanol Production

Electricity (Cellulosic Ethanol)

Transport, Storage, and Distribution of Ethanol
Refueling Stations
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Accurate Ethanol Energy Analysis Must Account for Increased Productivity in Farming Over Time
0.65

?
0.60
Bushels/lb. Fertilizer

0.55
0.50

U.S. Corn Output Per Pound of Fertilizer Has Risen by 70% in The Past 35 Years

Precision farming, etc.?

0.45 0.40 0.35 0.30 1965 1970 1975 1980 1985 1990 1995 2000 2005

Based on historical USDA data; results are 3-year moving averages

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Improved Technology Has Reduced Energy Use and Operating Costs in Corn Ethanol Plants
70,000 60,000 50,000 1980s 2000s

Btu/Gallon

40,000 30,000 20,000 10,000 0 Wet Mill Dry Mill

From Argonne’s discussions with ethanol plant designers, USDA data, and other reported data
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One-Third of Corn Kernel Mass Ends as Animal Feed (a Co-Product) in Ethanol Plants

Starch

Ethanol

2003 North American DDGS Consumption
Dairy: 46%

Distillers Dry Grains and Solubles (DDGS)

Beef: 39% Poultry: 4% Swine: 11%

Protein

Source: Commodity Specialist Co. (in RFA, 2005)

Carbon Dioxide

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Accounting for Animal Feed Is a Critical Factor in Ethanol’s Lifecycle Analysis
Allocation Method Weight Energy content Process energy Market value Displacement Wet milling 52% 43% 36% 30% ~16% Dry milling 51% 39% 41% 24% ~20%

Argonne uses the displacement method, the most conservative approach.

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Energy Effects of Fuel Ethanol Depend on the Type of Energy Being Analyzed
2.5
Btu for Fuel Production Btu in Fuel

2.0

Total Energy

1.5

Fossil Energy Petroleum Energy

1.0

0.5

0.0
RFG Corn Corn EtOH: EtOH: DM WM Cell. EtOH RFG Corn EtOH: DM Corn EtOH: WM Cell. EtOH RFG Corn EtOH: DM Corn EtOH: WM Cell. EtOH

Total Btu Spent for One Btu of Gasoline and Ethanol Available at Fuel Pumps
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Most Recent Studies Show Positive Net Energy Balance for Corn Ethanol
60,000 40,000
Lorenz&Morris NR Canada Shapouri et al. Wang Kim &Dale Graboski Kim &Dale Delucchi Agri. Canada Wang et al. Marland&Turhollow Shapouri et al.

20,000
Net Energy Value (Btu/gallon)

0 -20,000 -40,000 -60,000 -80,000
Cham bers et al. Weinblatt et al.

Ho Keeney&DeLuca Pim entel Pim entel Pim entel Pim entel &Patzek

Patzek

-100,000 -120,000 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006
Energy balance here is defined as Btu content a gallon of ethanol minus fossil energy used to produce a gallon of ethanol

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Energy in Different Fuels Can Have Very Different Qualities
Fossil Energy Ratio (FER) = energy in fuel/fossil energy input
10.31

2.0

1.5

1.0

1.36

0.5

0.98 0.81 0.45

0.0

Cell. EtOH

Corn EtOH

Coal

Gasoline

Electricity

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Comparative Results Between Ethanol and Gasoline Are More Relevant to Policy Debate

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Corn EtOH Reduces GHGs by 18-29% While Cellulosic EtOH Yields 85-86% Reduction, on Per Gallon Basis of EtOH Used
0%

-20% -26% -40%

-18% -29%

-21%

-60%

-80% -85% -100%
E10 GV: DM Corn EtOH E10 GV: WM Corn EtOH E10 GV: Cell. EtOH E85 FFV: DM Corn EtOH E85 FFV: WM E85 FFV: Cell. Corn EtOH EtOH

-86%

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.
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Debate on Energy Balance Itself May Have Little Practical Meaning
 Though self evaluation of a fuel’s 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 fuel’s effects is to compare the fuel (e.g., ethanol) with those to be displaced (e.g., gasoline)




 

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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 Switch from natural gas to coal in ethanol plants
Potential use of marginal land for additional corn production

Challenges

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

Population (in million)
Gasoline market: billion gallons Diesel market: billion gallons

296
140 50

1,306
16 24

Corn ethanol production: billion gallon Corn production: million tons
Arable land: million hectares



4.2 332
186

0.3 128
130

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
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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

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