Ethanol

Ethanol

• Conversion of sugars to ETOH

• The manufacture of alcoholic beverages originated over 5000 years ago– Water was generally impure and thus fermented

juices provided a level of protection from spoilage by their high alcohol content

Ethanol as a fuel• Long History

– Anhydrous ethanol used as an internal combustion engine fuel in the late 19th century

– In 1906 Congress removed the tax on ethanol to encourage farmers to use it as a fuel

– With appropriate pre-treatment various forms of biomass can be used

• Brazil National Alcohol Program– Effort to replace gasoline with ethanol

– Since 1975 over 50 billion liters of alcohol made

– 40% of Brazil’s 14 million cars used ethanol (95% ETOH/5% H20)

– 60% used 78% gasoline 12% ETOH

• US is the second largest alcohol producer– 1980 Energy Security Act

– Gasohol - 10% ETOH - about 7% of total nationwide gas sales• lead free, produces less NOx and CO

– 2001 1.8billion gallons of Ethanol produced mainly from corn

• Cost-competitiveness based solely on government subsidies

Ethanol fuel properties in relation to fuel performance

Energy density

Heat of vaporization

Lower flame temperature

Relative volume ofcombustion products

Octane Number

0.65-0.69

2.3

0.976

1.07

1.15

Lower mpgLarger tank

More air to cylinderIncreased powerDecreased cooling needs

Higher efficiencyin optimized engine

Increases work from gas expansion

Allows increased compression ratio and hence higherPower and efficiency

PropertyEthanol/Gasoline

ValueImpact

From Lynd 1996;Bailey 1996

Reasons to use Ethanol• Energy security• Ethanol offers substantial environmental

benefits. – Ethanol makes gasoline burn cleaner. – Ethanol reduces greenhouse gas emissions.

• Ethanol is made from abundant renewable resources.

• Ethanol is good for farmers and rural economy.

Corn Milling Liquefaction Saccharification Fermentation

Distillation Dehydration

Centrifugation

Evaporation

Dry FeedMixing Drying Cooling

Corn

-Amylase Gluco-amylase Yeast

Fuel GradeEthanol

Denaturant

Distillers Dried Grains w/ soluble

Dry Milling Simplified Process

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are needed to see this picture.

Poplars

Poplar Plantation

Poplar Cutting

Switchgrass Stand

Switchgrass

Switchgrass Bale

Size ReductionDilute AcidPretreatment

Liquid Solid Separation

DetoxificationVia

Ion Exchange

Enzyme Production SSCF Fermentation

SeparationSolids ProcessingCogen

Biomass

Fuel GradeEthanol

Simplified Bioethanol Process

Current Ethanol Costs

Net Feedstock Costs

Other Operating Costs

Total Production Costs

Annualized Capital Costs

Selling Price

0.54

0.42

0.96

0.26

1.22

0.48

0.46

0.94

0.22

1.16

$/gal

Dry Mill Wet Mill

0.37

0.25

0.62

0.54

1.16

Cellulosic(estimate)

Effect of Biomass Cost on Ethanol Production Cost

Natural Vegetation and Ag/Urban Waste

From Lynd (1996)

Mixed paperPackingUrban woodYard wasteAgricultural residuesForest residuesWood processing residues

Total

2614

411

12093

187

Waste category Availability

(million dry tons)

Waste Ag Cellulosics

• Corn stover is available in the highest amounts - 100 to 200 million tons per year.

• Bagasse could contribute another 700,000 tons.

• If all of the corn stocks and bagasse were collected, about 6.5 billion gallons of ethanol could be produced annually.

• Only 30 to 60% of the total stover and bagasse could be collected, reducing the potential ethanol to 2 to 4 billion gallons annually.

Sugarcane, Corn, Switchgrass Comparison

Crop Yield (tons/acre)Fermentation Sugar (tons/acre)Ethanol from 1° sugars (gallons/acre)Harvested Cellulosics (tons/acre)Ethanol from Cellulosics (gallons/acre)

Total Ethanol (gallons/acre)

Cane

293.4

54726

1741

2288

Corn

92.5

3222

125

447

Switchgrass

8n/an/a7.2

490

490

Variability of the literature calculations

AcresLand Need

EthanolRequired

EthanolYield

BiomassYield

AcresGallons Ethanol

1( ) Tons Biomass

Acre

( )Tons Biomass

Gal Ethanol( )

Hohenstein&

Wright

Rainey&

Mann

Wright et al.

Cook &Beyea

Downing et al.

Switchgrass

GeneralSRWC

HEC

Energy cane

Hybrid Poplars

Natural Forests

LowHigh

LowHighLowHighLowHighLowHighLowHigh

2 (4)6 (14)

5 (12)14 (32)4 (10)8 (17)

5(12)

9 (20)16 (35)16 (35)

4 (9)10 (22)

2 (4)11 (25)5 (12)

21 (48)

1 (2)2 (4)

4 (10)7 (15)7 (15)9 (20)

5 (11)10 (22)

Plant Type

Source

tons/acre (metric tons/hectare)

Biomass Yields from Literature

Gross Calculation

• 195 billion gallons of ethanol needed

• Using Switchgrass

• 195 to 600 million acres of land

Land Use in the Contiguous 48 States

Use Acreage(Million Acres)

Proportion ofTotal Area

(%)

Grassland Pasture& Range

ForestCroplandSpecial UseOther Use

589

55946019492

31

302410

5

Environmental Impact• Food vs. energy

• Land use competition

• Soil quality

• Water quality

• Chemical inputs

• Biodiversity– monoculture

– suitability for wildlife habitat

– landscape effects

– stability

Greenhouse gas emissions reduction

• Burning fossil fuels converts “old biomass” into new CO2” - this then contributes to the greenhouse effect

• Burning “new biomass” contributes no net CO2 if we replant the harvested biomass or burn biomass specifically grown for energy generation (energy crops)

Greenhouse gas emissions (Corn)Shaporri/IPCC Robertson Wagner-Riddle

N2O emissions(lbs C/gal of gasoline equivalent) 3.1 2.3 2.4CO2 emissions from ethanol fuel cycle(lbs C/gal of gasoline equivalent) 8.3 7.4 7.6Total Ethanol Emissions to GasolineEmissions 1.19 1.08 1.09Total Ethanol Emissions to GasolineEmissions with Co-product Credits 1.16 1.06 1.08

Greenhouse gas emissions (Biomass)

Corn(Shap/IPCC)

Switchgrass(Robertson)

SWRC(Robertson)

Nitrogen Use (CO2 Equivalent)(lbs/C/acre) 681 227 40

N2O emissions(lbs C/gal of gasoline equivalent) 3.1 1.6 0.28

CO2 emissions from ethanol fuel cycle(lbs C/gal of gasoline equivalent) 8.3 1.7 1.7

Ratio of Total Ethanol Emissions to GasolineEmissions 1.19 0.48 0.29

Ratio of Total Ethanol Emissions to GasolineEmissions with Co-product Credits 1.16 NA NA

Gasoline requirements per region (% of Total - 1.2 billion gallons)

27%

16%14%15% 8%

5%

3%

12%

5%

> 5 to 10%

> 10 to 20%

> 20%Do to rounding values may not equal 100%

0

50

100

150

200

250

300

350

US Region

2000 Ethanol Requirements

2010 Ethanol Requirements

Production Capacity

Pipeline Infrastructure

80

90

100

110

120

130

140

150

160

170

2000 2005 2010 2015 2020 2025

Year

Fuel Amount (billion gallons)

2012 Kyoto

Project Consumption

Permitted Consumption

Fuel Consumption

0

20

40

60

80

100

120

140

160

180

2000 2005 2010 2015 2020 2025

Year

Fuel Amount (billion gallons)

Baseline Consumption

Gasoline Use

Ethanol Production

Ethanol Production

0

20

40

60

80

100

120

140

160

180

2000 2005 2010 2015 2020 2025

Year

Fuel Volume (billion gallons)

Baseline Consumption

E0 E10

E85

Fuel Mix