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Fuel-Cycle Energy and Greenhouse

Emission Impacts of Fuel Ethanol

Michael WangCenter for Transportation Research

Argonne National Laboratory

Presentation at EPA Cincinnati

Cincinnati, Ohio, May 8, 2003



Cycles for Vehicle/Fuel Systems

The Illustration is for Petroleum-Based Fuels

Vehicle Cycle

Fuel Cycle

Well to Pump

P um p t o

Wh e el s

WTP: well-to-pump

PTW: pump-to-wheels

WTW: well-to-wheels (WTP + PTW)



The GREET (G reenhouse gases,

R egulated E missions, and E nergy

use in T ransportation) Model GREET includes emissions of greenhouse gases

CO2, CH4, and N2O

VOC, CO, and NOx as optional GHGs

GREET estimates emissions of five criteria pollutants

VOC, CO, NOx, PM10, and Sox

Total and urban emissions separately GREET separates energy use into

All energy sources

Fossil fuels (petroleum, natural gas, and coal)

Petroleum

The GREET model and Its documents are available at

http://greet.anl.gov; there are about 800 registered GREET users



U.S. Fuel Ethanol Production

and Use Have Increased Steadily

Source: Renewable Fuels Association’s

2003 Ethanol Industry Outlook Report.

In 2002, the U.S. used

2.1 billion gallons of fuel ethanol

Type Purpose Mil. Gal.

FRFG Oxygenate (E6-E10) 700

F.Winter Oxy. Fuels Oxygenate (E10) 250

MN Oxy. Fuels Oxygenate (E10) 250

Conv. Gasoline Octane/Extender 900

Total 2,100



Energy Effects of Fuel Ethanol

Have Been Subject to Debate

Some studies, especially those completed between late

1980s and early 1990s, concluded negative energy

balance value of ethanol

Those past studies basically examined energy use of

producing ethanol

Though self evaluation of ethanol’s energy balance is easy

to understand, it may not be useful to fully understand trueenergy benefits of fuel ethanol

A more complete way is to compare fuel ethanol with the

fuels to be displaced by ethanol (i.e., gasoline)

The GREET model has been applied to conduct a

comparative analysis between ethanol and gasoline



Emission Effects of Fuel Ethanol Were

Not Addressed on the Fuel-Cycle Basis

Past emission studies focused mainly on ethanol’sevaporative emissions and its effects on vehicle tailpipe

emissions

Well-to-pump emissions were identified for ethanol andgasoline only in a piece-meal way

Petroleum refinery emissions

Ethanol plant emissions GHG emissions were simply ignored in some debatable

studies

Emissions of fuel ethanol need to be evaluated in aholistic and comparative way

For criteria pollutant emissions, future emission controls

for WTP and vehicle activities are important



GREET Calculation Logic for Production Activities

Inputs

EmissionFactors

CombustionTech. Shares

Energy

Efficiencies

FacilityLocation Shares

Fuel TypeShares

Energy Use byFuel Type

TotalEmissions

UrbanEmissions

Calculations



GREET Calculation Logic

for Transportation Activities

Energy Intensity(Btu/ton-mile)

Energy Intensity(Btu/ton-mile)

Transport

Distance (mi.)

Transport

Distance (mi.)

Energy Consumption

(Btu/mmBtu Fuel Transported)

Emission Factors

(g/mmBtu fuel burned)

Emission Factors

(g/mmBtu fuel burned)

Share of Process Fuels

Emissions by Mode

(g/mmBtu Fuel

Transported)

Mode ShareMode Share

Energy Use by Mode

(Btu/mmBtu Fuel Transported)

Emissions (g/mmBtu

Fuel Transported)



GREET Is Designed to

Conduct Stochastic Simulations

Distribution-Based Inputs Generate Distribution-Based Outputs



Petroleum Refining Is the Key

Energy Conversion Step for Gasoline

Petroleum Recovery (97%)

Gasoline at Refueling Stations

Petroleum Transport

and Storage (99%)

Transport, Storage, and

Distribution of Gasoline (99.5%)

MTBE or EtOH for Gasoline

WTP Overall Efficiency: 80%

Petroleum Refining to Gasoline (84.5-86%,

Depending on Oxygenates and Reformulation)

Petroleum Refining to Gasoline (84.5-86%,

Depending on Oxygenates and Reformulation)

NG to MeOH Corn



Key Issues for

Simulating Petroleum Fuels

Beginning in 2004, gasoline sulfur content will be

reduced nationwide from the current level of 150-

300 ppm to 30 ppm In addition, marginal crude has high sulfur content

Desulfurization in petroleum refineries adds stress

on refinery energy use and emissions

Ethanol could replace MTBE in RFG nationwide

Energy and emission differences in MTBE and ethanol

Differences in gasoline blend stocks for MTBE and

ethanol



Ethanol WTP Pathways Include Activities

from Fertilizer to Ethanol at Stations

Agro-Chemical Production

Corn FarmingCorn Farming

Refueling Stations

Agro-Chemical Transport

Corn Transport

Transport, Storage, and

Distribution of Ethanol

Electricity

(Cell. Ethanol)

Woody Biomass FarmingWoody Biomass Farming Herbaceous Biomass FarmingHerbaceous Biomass Farming

Woody Biomass Transport Herbaceous Biomass Transport

Animal Feed

(Corn Ethanol)

Ethanol ProductionEthanol Production



Recycling of Carbon by Ethanol

Fuel Results in Large CO2 Benefits for It

Ethanol plant

Carbon in

ethanol

Carbon in

corn kernels

Carbonin soil

Carbonin crop

residue

CO2 via photosynthesis

CO2 in theatmosphere

CO2 emissionsfrom ethanol

combustion

CO2emissionsduring

fermentation

K P t f Eth l’



Key Parameters for Ethanol’sEnergy and Emission Effects

Energy use for chemicals

production

Fertilizers (N, P2O5, K2O)

Herbicides

Insecticides

Farming

Corn and biomass yield

Chemicals use intensity

Energy use intensity

Soil N2O and NOx emissions Soil CO2 emissions or

sequestration

Ethanol production

Corn ethanol: wet vs. dry

milling

Ethanol yield Energy use intensity

Co-product types and yields

Vehicle fuel economy Gasoline vehicles with E10

Flexible-fuel vehicles with E85

S C O f



0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

1965 1970 1975 1980 1985 1990 1995 2000 2005

B u s h

e l s / l b .

F e r t i l i z e r

U.S. Corn Output Per Pound of Fertilizer

Used Has Risen (3-yr Moving Average)

Source: from USDA data.

Precision

farming, etc.?

?Some earlier studies

showed negative energy

balance for corn ethanol



N2O and NOx Emissions from Nitrogen

Fertilizer Are a Major Emission Source

Some nitrogen fertilizer is converted into N2O

and NOX via nitrification and denitrification in

farmland

Depending on soil type and condition, 1-3% of

N in nitrogen fertilizer is converted into N in

N2O

On the well-to-wheels basis, N2O emissions

from nitrogen fertilizers could account for up to25% of total GHG emissions from corn ethanol



Technology Has Reduced

Energy Use Intensity of Ethanol Plants

Source: from Argonne’s discussions with ethanol plant designers and recent USDA data.

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

B t u

/ G a l l o n

Wet Mill Dry Mill

1980s

2000s



Well-to-Gate Energy andEmissions Allocated to Co-Products(Animal Feed) Vary by Allocation Method

Allocation Method Wet milling Dry milling

Weight 52% 51%

Energy content 43% 39%

Process energy 31% 34%

Market value 30% 24%

Displacement ~16% ~20%• Weight and energy methods no longer used

• Some studies did not consider co-products at all



0.0

0.5

1.0

1.5

2.0

2.5

3.0

T o t a l

E n e r g y

F o s s i l

P e t r o l e u m

T o t a l

E n e r g y

F o s s i l

P e t r o l e u m

T o t a l

E n e r g y

F o s s i l

P e t r o l e u m

RFG Corn EtOH Cell. EtOH

B t u / b t u

Energy Benefits of Fuel Ethanol Lie

in Fossil Energy and Petroleum Use

Energy in fuel

Energy for

producing fuel

Uncertainty

Range

Energy Use for Each Btu of Fuel Used



Energy in Different Fuels

Can Have Very Different Qualities

Fossil Energy Ratio (FER) =

energy in fuel/fossil energy input

1.4

0.980.8

0.42

0

1

2

3

4

Cell. EtOH Corn EtOH Coal Gasoline Electricity

F o s s i l E n e r g y R a t i o

18.5

Petroleum energy ratios for ethanol, coal,

and electricity are much greater than one.

I n c r e a s e i n E n e r g y Q u a l i t

y



Changes in Energy Use Per Gallon

of Ethanol Used (Relative to Gasoline)

-120000

-80000

-40000

0

40000

80000

120000

T o t a l

E

n e r g y

F o s s i l

P e t r

o l e u m

T o t a l

E

n e r g y

F o s s i l

P e t r

o l e u m

T o t a l

E

n e r g y

F o s s i l

P e t r

o l e u m

T o t a l

E

n e r g y

F o s s i l

P e t r

o l e u m

E85 FFV: Corn EtOH E85 FFV: Cell. EtOH E10 GV: Corn EtOH E10 GV: Cell. EtOH

B t u

C h a n g e / E t O H G a l l o n



Changes in Greenhouse Gas Emissions per

Gallon of Ethanol Used (Relative to Gasoline)

-10000

-8000

-6000

-4000

-2000

0 C O 2

G H G

C O 2

G H G

C O 2

G H G

C O 2

G H G


G H

G

C h a n g e i n G

r a m s / E t O H G a

l l o



Changes in Greenhouse Gas Emissions

per Mile Driven (Relative to GVs)

-90%

-80%

-70%

-60%

-50%

-40%

-30%

-20%

-10%

0%

C O 2

G H G

C O 2

G H G

C O 2

G H G

C O 2

G H G


C h a n g e

s R e l a t i v e t o G V s

T t ti L i ti C Aff t



Transportation Logistics Can Affect

Ethanol Emissions

Rail

Barge

Truck

Rail

Barge

Ocean

Tanker

Truck

Truck

Local

Collection

Long-Distance

TransportationLocal

Distribution

Ethanol

Plants

Bulk

Terminals

TerminalsRefueling

Stations

T t ti f Mid t Eth l t



Transportation of Midwest Ethanol to

California is Accomplished via Rail and Ocean

Based on Pat Perez of CEC.

Midwest Supply - Majority of Supply to California

SF BayRefineries

Los Angeles

Refineries

Oregon

Terminals

Changes in Energy Use by Corn



Changes in Energy Use by Corn

Ethanol: Midwest Use vs. California Use

-100000

-80000

-60000

-40000

-20000

0

20000

40000

T o t a l

E

n e r g y

F o s s i l

P e t r o l e u m

T o t a l

E

n e r g y

F o s s i l

P e t r o l e u m

T o t a l

E

n e r g y

F o s s i l

P e t r o l e u m

Corn EtOH in Midwest Corn EtOH in CA via Rail Corn EtOH in CA via Ocean

B t u C

h a n g e / E t O H G a

l l o n

Results are based ethanol in E85



Changes in Greenhouse Gas Emissions by

Corn Ethanol: Midwest Use vs. California Use

-4000

-3000

-2000

-1000

0 C O 2

G H G

C O 2

G H G

C O 2

G H G

Corn EtOH in Midwest Corn EtOH in CA via Rail Corn EtOH in CA via Ocean

G H

G

C h a n g e i n G r

a m s / E t O H G a l l o

Results are based ethanol in E85

Energy Balance of Ethanol



Energy Balance of Ethanol

Results Among Studies

-40,000

-30,000

-20,000

-10,000

0

10,000

20,000

30,000

40,000

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

N e t E n e r g y V a l u e ( B t u / g a l l o n )

Ho

Marland and Turhollow

Pimentel Pimentel

Keeney and DeLuca

Lorenz and Morris

Shapouri et al.

Shapouri et al.

Wang et al.

Agri. Canada

Kim and

DaleGraboski

Wang



Ethanol GHG Emission Changes Among Studies

-80%

-60%

-40%

-20%

0%

20%

40%

60%

80%

100%

EPA

(1989):

E100

EPA

(1989):

E85

Ho

(1990):

E100

Marland

(1991):

E100

Delucchi

(1991):

E100

Ahmed

(1994):

E100

Delucchi

(1996):

E95

Wang

(1996):

E100

Wang

(1996):

E85

Wang

(1997):

E85

Agri.

Can.

(1999):

E85

Delucchi

(2001):

E90

Wang

(2003):

E85

G H G C h a n g e s

In long Run Cellulosic Ethanol Could



In long Run, Cellulosic Ethanol Could

Play an Important Role in Energy Benefits

0 1,000 2,000 3,000 4,000 5,000 6,000

Renewable Electrolysis H2 FCV

Cellulosic EtOH FCV

NG Central H2 FCV

NG FTD HEV

Diesel HEV

Gasoline FCV

Gasoline HEV

Baseline GV

WTW Per-Mile Fossil Fuels Energy Use (Btu/mi.)

PTW

WTPOil

Natural Gas

Non-Fossil Domestic



Cellulosic Ethanol Could Also Play

an Important Role in GHG Reductions

-300 -200 -100 0 100 200 300 400 500

Renewable Electrolysis H2 FCV

Cellulosic EtOH FCV

NG Central H2 FCV

NG FTD HEV

Diesel HEV

Gasoline FCV

Gasoline HEV

Baseline GV

WTW Per-Mile GHG Emissions (g/mi.)

PTW

WTP

Oil

Natural Gas

Non-Fossil Domestic



Conclusions

Any type of fuel ethanol helps substantially reducetransportation’s fossil energy and petroleum use

Though studies now show that ethanol haspositive energy balance values, energy balance

values alone are not meaningful

Corn-based fuel ethanol achieves moderate

reductions in GHG emissions

Cellulosic ethanol will achieve much greater

energy and GHG benefits

Some WTW Analysis



Some WTW Analysis

Issues Need to Be Noted

Multiple products System expansion vs. allocation (GREET takes both)

System expansion: allocation vs. attribution of effects

Technology advancement over time Current vs. emerging technologies – leveling comparison field

Static snap shot vs. dynamic simulations of evolving technologiesand market penetration over time

Dealing with uncertainties Risk assessment vs. sensitivity analysis

Regional differences, e.g, CA vs. the rest of the U.S.

Trade-offs of impacts WTW results are better for identifying problems than for

giving the answers

fuel cycle energy

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