MEMORANDUM 

TO: Melissa Weitz, EPA 

FROM: Deb Bartram and Sarah Holman, ERG 

DATE: 19 October 2006 

SUBJECT: Assessment of Greenhouse Gas Emissions from Wastewater Treatment of 

U.S. Ethanol Production Wastewaters 

As directed by EPA, ERG is supporting the identification of improvements to the Wastewater 

source category of the Inventory of U.S. Greenhouse Gas Emissions and Sinks. This 

memorandum presents a discussion of ethanol production in the United States, including a 

preliminary profile of operations, a description of the primary production processes, and initial 

estimates of the greenhouse gas (GHG) emissions that could be emitted by wastewater treatment 

operations conducted at these facilities. This memorandum also includes a list of potential next 

steps to further investigate this industry segment. 

1.0 INTRODUCTION

Wastewater treatment processes can produce anthropogenic methane (CH4) and nitrous oxide 

(N2O) emissions. Wastewater from industrial sources is typically treated to remove soluble 

organic matter, suspended solids, pathogenic organisms, and chemical contaminants. Soluble 

organic matter is generally removed using biological processes in which microorganisms 

consume the organic matter for maintenance and growth. The resulting biomass (sludge) is 

removed from the effluent prior to discharge to the receiving stream. Microorganisms can 

biodegrade soluble organic material in wastewater under aerobic or anaerobic conditions, where 

the latter condition produces CH4. 

The generation of N2O may also result from the treatment of wastewater during both nitrification 

and denitrification of the nitrogen present, usually in the form of urea, ammonia, and proteins. 

These compounds are converted to nitrate (NO3) through the aerobic process of nitrification. 

Denitrification occurs under anoxic conditions (without free oxygen), and involves the biological 

conversion of nitrate into dinitrogen gas (N2). N2O can be an intermediate product of both 

processes, but is more often associated with denitrification. 

In this memorandum, ERG presents a summary of U.S. ethanol production operations, including 

the types of wastewaters generated and the types of wastewater treatment operations that may be 

performed. Treatment may either occur on site or off site at centralized treatment systems (e.g., 

POTWs). However, this analysis focuses on on-site wastewater treatment, and the potential for 

those treatment systems to produce GHG. ERG then presents a preliminary estimate of the 

potential GHG emissions from this industry. 

1 
Memorandum 

19 October 2006 

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2.0 OVERVIEW OF ETHANOL INDUSTRY

Ethanol, or ethyl alcohol, is produced primarily for use as a fuel component, but is also used in 

industrial applications and in the manufacture of beverage alcohol. Ethanol is used industrially 

in solvents, thinners, detergents, toiletries, cosmetics, rubbing alcohol, pharmaceuticals, and the 

synthesis of chemical intermediates (e.g., ethylene glycol). In 1997, the fuel demand for ethanol 

was approximately five times greater than the industrial demand for ethanol. The industrial 

demand for ethanol increased by approximately 12 percent from 1980 to 1997, whereas the fuel 

demand for ethanol increased by over 1,000 percent during the same period (Mannsville 

Chemical, 1998). See Table 2-1. 

Table 2-1. Historic Ethanol Demand 

1980 1985 1990 1993 1994 1995 1996 1997 

Percent 

Increase

Industrial Demand 

(Millions of Gallons of Ethanol) 223 210 244 240 245 250 255 250 12% 

Fuel Demand 

(Millions of Gallons of Ethanol) 105 673 940 1,150 1,280 1,350 900 1,200 >1,000%

Source: (Mannsville Chemical, 1998) 

After the U.S. oil supply crisis of the early 1970s, ethanol was produced mainly as a fuel to 

extend the supply of gasoline. Since that time, ethanol has been used increasingly as an octane 

enhancer and oxygenate in gasoline. Section 211(k) of the 1990 Amendments to the Clean Air 

Act mandated that gasoline sold in geographic areas with a certain level of carbon monoxide 

pollution contain two percent oxygen by weight. This oxygen requirement, which was recently 

remanded (U.S. EPA, 2006) in response to the U.S. Energy Policy Act of 2005 (EPACT2005), 

was met through the addition of oxygenates, such as methyl tert-butyl ether (MTBE), ethanol, 

and methanol, to gasoline. Over 80 percent of the ethanol produced in 2004 was used in oxygenmandated areas including California, New York, Connecticut, Illinois (Chicago), Wisconsin 

(Milwaukee), and Minnesota. The remaining 20 percent was used to increase the octane rating 

in gasoline across the United States (USDA, 2005). 

Despite the remand of the oxygen requirement, ethanol production is expected to continue to 

increase, due in part to EPACT2005, which created a national Renewable Fuels Standard (RFS). 

According to EPACT2005, renewable fuel use must increase from 4 billion gallons in 2006 to 

7.5 billion gallons by 2012 (RFA, 2006b). Additionally, refiners must meet requirements for 

reformulated gasoline including volatility and aromatics emissions limits, which can be met 

through MTBE or ethanol blending. The U.S. Department of Energy - Energy Information 

Administration (EIA) expects that refiners will stop blending MTBE by 2008 due to groundwater 

contamination concerns, and refiners will continue to blend ethanol (EIA, 2006). 

Appendix A contains the Renewable Fuel Association (RFA) listing of U.S. ethanol production 

facilities (both currently operating and under construction), locations, feedstocks, and production 

capacities. Ethanol production facilities are concentrated in the middle of the United States, with 

the largest number of facilities located in Iowa, Nebraska, Minnesota, and South Dakota. In July 
Memorandum 

19 October 2006 

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of 2006, ethanol production capacity was 4,818 million gallons per year (MGY) and the 

additional capacity from facilities under construction or expanding production was 2,431 MGY. 

The individual facility ethanol production capacity ranges from 0.4 MGY to 290 MGY. (RFA, 

2006a) Over the past eight years, ethanol production has been between 75 and 93 percent of 

ethanol production capacity (RFA, 2006c), as shown in Table 2-2. 

Table 2-2. Historic Ethanol Production vs. Production Capacity 

1998 1999 2000 2001 2002 2003 2004 2005 

Ethanol Production 

(Millions of Gallons of Ethanol) 

1,400 1,470 1,630 1,770 2,130 2,800 3,400 3,904 

Ethanol Production Capacitya

(Millions of Gallons of Ethanol) 

1,702 1,749 1,922 2,347 2,707 3,101 3,644 4,336 

Source: (RFA, 2006c) 

a – Production capacities from January of following year. 

Ethanol can be produced from the fermentation of sugar-based feedstocks (e.g., molasses and 

beets), starch- or grain-based feedstocks (e.g., corn, sorghum, and beverage waste), and 

cellulosic biomass feedstocks (e.g., agricultural wastes, wood, and bagasse). Ethanol can also be 

produced synthetically from ethylene or hydrogen and carbon monoxide. Synthetic ethanol 

production represents a small percentage of the total ethanol production (approximately 7.2 

percent in 1997 and 5.8 percent in 2000 (projected) (Mannsville Chemical, 1998). Table 2-3 

contains a timeline of synthetic and fermentation ethanol production. Using the 1997 synthetic 

ethanol production number, which remained roughly stable for about 12 years, the 2006 

percentage of synthetic ethanol production would be 2.1 percent. Due to these small 

percentages, synthetic ethanol production is not discussed further in this memorandum. 

 

Table 2-3. Historic Ethanol Production 

Ethanol Production 

Type 1970 1975 1980 1985 1990 1993 1994 1995 1996 1997 

2000 

(Projected)

Synthetic Production 

(Millions of Gallons of 

Ethanol) 

295 216 219 99 82 100 108 92 95 100 110 

Fermentation Production 

(Millions of Gallons of 

Ethanol) 

0 1 58 625 900 1,250 1,350 1,400 980 1,290 1,800 

Source: (Mannsville Chemical, 1998) 

EIA projects that U.S. cellulosic biomass ethanol production will reach 25 to 830 million gallons 

per year by 2025, depending on the case, as shown in Figure 2-1 (EIA, 2005). However, 

cellulosic biomass ethanol production is currently in an experimental stage in the United States, 

and thus, is not discussed further in this memorandum. 
Memorandum 

19 October 2006 

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Figure 2-1. EIA Projections of Ethanol Production 

Source: National Energy Modeling System (EIA, 2006) 

 

The fermentation of corn is the principal ethanol production process in the United States, and 

thus, is the focus of this memorandum. Corn-based ethanol has become the most commonly 

used octane enhancer and oxygenate due to the plentiful supply of corn in the Midwest, 

improvements in corn production, and the ban of MTBE in certain states due to groundwater 

contamination. As shown in Figure 2-1, EIA projects that corn-based ethanol production will 

continue to increase for at least the next 6 years, and potentially more. 

According to the RFA, 82 percent of ethanol production facilities use corn as the sole feedstock 

and 7 percent of facilities use a combination of corn and another starch-based feedstock. The 

remaining 11 percent of ethanol production facilities use one or a combination of the following 

feedstocks: beverage waste; cheese whey; seed corn; milo (sorghum); wheat; and sugars. (RFA, 

2006a) Figure 2-2 depicts the distribution of production methods in use in the U.S. 
Memorandum 

19 October 2006 

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Corn Fermentation

Corn and Other 

Starch 

Fermentation

Other 

Starch/Cheese 

Whey/Sugars 

Fermentation

Synthetic

Figure 2-2. Distribution of U.S. Ethanol Production 

3.0 STARCH-BASED ETHANOL PRODUCTION PROCESSES

Because the fermentation of corn is the principal ethanol production process in the United States 

and projections indicate that it will continue to be for a significant period of time, this 

memorandum focuses on the starch-based ethanol production process and wastewaters. 

Ethanol is produced from corn (or other starch-based feedstocks) primarily by two methods: wet 

milling and dry grinding. In this memorandum, the dry grinding process will be referred to as 

“dry milling”, as it is often referred to in the ethanol industry. The main differences between the 

wet milling and dry milling processes are the initial treatment of feedstock and the co-product 

production process. Wet milling facilities generate large volumes and variety of co-products, 

and generate large volumes of ethanol, relative to dry milling facilities. Dry milling facilities 

typically produce only one co-product: distillers’ dried grains with solubles (DDGS). 

Historically, the majority of ethanol was produced by the wet milling process, but now the 

majority is produced by the dry milling process. In the early 1980s, there were a few large wet 

milling ethanol facilities in operation and many small inefficient dry milling ethanol facilities 

(USDA, 2005). Most of these small dry milling facilities went out of business in the 1980s due 

to inefficiency, and were replaced by larger and more efficient dry milling facilities. Because 

wet milling facilities are more equipment and capital intensive and less efficient than newer dry 

milling facilities, dry milling capacity has increased rapidly over the past 10 years. 

Approximately 90 percent of currently operating milling facilities are dry mills, and dry milling 

ethanol production accounts for approximately 75 percent of total ethanol milling production, as 

is discussed in Section 5.0. (Rausch, 2006) (USDA, 2005) 

3.1 Dry Milling

This section discusses the dry milling process and its co-products and wastewaters. 

3.1.1 Dry Milling Process 

In the dry milling process, which is depicted in Figure 3-1, corn kernels (or other starch-based 

feedstock) are processed in the following major stages: 
Memorandum 

19 October 2006 

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 Milling (grinding); 

 Cooking/Liquefaction; 

 Saccharification/Fermentation; 

 Distillation; 

 Dehydration; 

 Denaturing; and 

 Co-products processing. 

In the milling stage, corn kernels are ground into flour, or “meal”, and processed without 

separating out the kernel’s component parts. In the cooking stage, the corn meal is slurried with 

water to form a mash (liquefaction). The mash is heated to break down the starch using an 

enzyme, alpha-amylase. 

The mash is cooled and transferred to a saccharification and fermentation stage. For 

saccharification, a second enzyme, gluco-amylase, is added to convert starch into dextrose, a 

simple sugar. Ammonia is added for pH control and as a nutrient to the yeast used for 

fermentation. During fermentation, the dextrose is converted to ethanol and carbon dioxide 

(CO2) exothermically. This CO2 is typically captured and sold for use in carbonated beverages 

and the manufacture of dry ice. During fermentation, the mash is agitated and kept cool to 

facilitate the activity of the yeast. 

The resulting "beer" from fermentation, which is 12 to 16 percent ethanol, is transferred to 

distillation columns where the ethanol is separated from the remaining "stillage." The ethanol is 

concentrated to 95 percent (190 proof) in the distillation columns and is then dehydrated to 99.5 

percent (198.6 to 199.9 proof) in a molecular sieve system. The anhydrous ethanol is typically 

blended with about 5 percent denaturant (e.g., gasoline) to render it undrinkable and thus not 

subject to beverage alcohol tax. 

The stillage from the bottom of the distillation columns is referred to as “whole” stillage and is 

handled in various ways. Dry milling facilities typically process a portion of the whole stillage 

to produce dried distillers grains and/or solubles co-products. 

During co-products production, solids are separated from the whole stillage using 

physical/mechanical separators, such as centrifuges, and the resulting liquid is referred to as 

“thin” stillage. Thin stillage may be processed through an evaporation stage, which serves to 

reduce wastewater output and produce syrup. This syrup may be dried to produce distillers dried 

solubles (DDS), which is sold as feed and/or fertilizer. The syrup from evaporation may also be 

added to the solids from mechanical separation, creating distillers wet grains (DWG). DWG 

may be dried to produce distillers dried grains with solubles (DDGS), which is sold as livestock 

feed. Other thin stillage processing techniques that are still developing in the United States 

include single cell protein production and membrane separation, which similarly result in feed 

and/or fertilizer (Wilkie et al., 2000). 
Memorandum 

19 October 2006 

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Milling 

(Grinding )

Dehydration

Distillation

Saccharification/

Fermentation

Cooking/

Liquefaction

Denaturing

Solids 

Separation Evaporation

Drying Drying

Corn 

(or other 

starch-based 

feedstock)

Alphaamylase

Water

Ammonia

Glucoamylase

CO2

Beer 

(12 to 16% 

Ethanol)

95% 

Ethanol

99.5%

Ethanol

Denaturant

Whole 

Stillage

Thin 

Stillage

Distillers Dried 

Grains (DDG) or 

Distillers Dried 

Grains with 

Solubles (DDGS)

Distillers Dried 

Solubles (DDS)

Evaporator 

Condensate

Recycle Recycle

Dehydration 

Column 

Bottoms

Boiler 

(Steam 

Production)

Air Pollution 

Control 

(Dryers and 

Fermentation )

Boiler 

Blowdown Scrubber 

Blowdown

Recycle Syrup

Yeast

Final Ethanol 

Product

Figure 3-1. Diagram of the Dry Milling Process

7 
Memorandum 

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3.1.2 Wastewaters from Dry Milling Process 

Process wastewaters generated from the dry milling ethanol production process, which are 

depicted in Figure 3-1, include the following: 

 Evaporator condensate (wastewater from thin stillage evaporation); 

 Equipment wash water (clean in place (CIP)); 

 Wet scrubber air pollution control device water; 

 Boiler blowdown; and 

 Dehydration column bottoms. 

Evaporator condensate typically contributes the majority of ethanol production process 

wastewater from dry milling facilities. Evaporator condensate and other wastewaters listed 

above are often commingled and recycled and/or treated on site in anaerobic wastewater 

treatment systems. Other wastewaters that are typically handled separately are noncontact 

cooling water, cooling tower blowdown, and reverse osmosis reject water. 

It is common practice at dry milling facilities, particularly at new dry milling facilities, to recycle 

portions of the whole stillage, thin stillage, and/or evaporator condensate back to the ethanol 

production process, typically to the cooking stage. Many relatively new dry milling facilities are 

considered “zero discharge” and recycle virtually all of their process wastewaters [many 

references]. Some facilities treat the process wastewater prior to recycle. Recycling and on-site 

treatment operations are discussed further in Section 4.0. 

3.2 Wet Milling

This section discusses the dry milling process and its co-products and wastewaters. 

3.2.1 Wet Milling Process 

In the wet milling process, corn (or other feedstock) is soaked or “steeped” in a dilute aqueous 

solution of sulfur dioxide to soften the kernels, to facilitate the separation of the kernel into its 

component parts (germ, fiber, gluten, and starch), and to remove soluble materials. The corn 

slurry is processed through a series of grinders to loosen the oil-containing germ. The corn oil 

from the germ may be extracted on site or the germ may be sold. The remaining fiber, gluten, 

and starch components are further segregated using centrifugal, screen, and hydroclonic 

separators. The fiber is processed into a wet feed product and the gluten is filtered and dried to 

produce a protein meal feed ingredient. The starch can be processed in three ways: dried and 

sold as dried or modified corn starch; processed into corn syrup; or fermented into ethanol. 

Refer to Figure 3-2 for a flow diagram of the wet-milling process. 
Memorandum 

19 October 2006 

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Steeping

Starch/Gluten 

Separation

Milling 

(Grinding)/ 

Fiber Separation

Milling 

(Grinding)/

Germ Separation

Starch 

Washing/

Separation

Fiber 

Washing

Evaporation

Drying

Drying

Corn 

(or other 

starch-based 

feedstock)

Sulfur 

Water Dioxide

Evaporator 

Condensate

Germ 

Oil

Gluten

Ethanol Corn Syrup

Light 

Steepwater

Corn Syrup

Starch

Ethanol

Heavy 

Steepwater

Germ 

Washing

Drying

Fermentation 

(Similar to 

Dry Milling)

Refining

Wash 

Water

Refining

Dried 

Germ

Wash 

Water

Wash 

Water

Corn 

Feed

Filtering/

Drying

Corn 

Gluten 

Meal

Corn 

Starch

Figure 3-2. Diagram of Wet Milling Process 

The wet milling fermentation process for ethanol production is similar to that for dry milling, 

which is described in Section 3.1. One difference is that the wet milling process uses sequential 

saccharification and fermentation stages, whereas the dry milling process uses a simultaneous 

saccharification and fermentation stage (Rausch, 2006). 

3.2.2 Wastewaters from Wet Milling Process 

Water resulting from the steeping process, “light steepwater” (4 to 8 percent solids), may be 

evaporated into “heavy steepwater” (35 to 40 percent solids), which is dried to produce corn 
Memorandum 

19 October 2006 

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gluten feed (CGF). The steepwater condensate from evaporation is typically treated on site in 

anaerobic systems (e.g., anaerobic lagoons) followed by aerobic polishing systems (Ruocco, 

2006b) (Rausch, 2006). 

Wet milling facilities may handle the whole stillage from ethanol production in a variety of 

ways. ERG obtained some information indicating that wet milling facilities typically do not 

produce co-products from whole stillage and, instead, discharge the whole stillage as wastewater 

(Lalley, 2002). However, ERG obtained other information indicating that wet milling facilities 

may process this stillage into distillers’ solubles (DS), recycle a portion of the stillage, and/or 

treat the resulting wastewaters on site (Ruocco, 2006b) (Rausch, 2006). 

The primary process wastewaters generated from the wet milling process, which are depicted in 

Figure 3-2, include the following: 

 Steepwater condensate; and 

 Wash waters from germ, fiber, and starch washing (a portion of which may be recycled to 

the steeping process (Rausch, 2006). 

Other process wastewaters of lesser volumes include those from the ethanol fermentation process 

and possibly from DS production. These wastewaters, which are also produced by dry milling 

operations, are discussed in Section 3.1.2 and depicted in Figure 3-2. 

4.0 WASTEWATER TREATMENT AND DISCHARGE OPTIONS

The wastewater generated at ethanol production facilities is handled in a variety of ways. The 

following sections describe the wastewater treatment systems operated at wet and dry milling 

facilities. 

4.1 Dry Milling Facilities

As described in Section 3.0, dry milling facilities commonly process whole stillage into coproducts through separation and evaporation processes. These facilities often combine the 

resulting evaporator condensate with other process wastewaters, such as CIP water, scrubber 

water, and boiler blowdown and anaerobically treat this wastewater using various types of 

digesters. 

One of the leading suppliers of anaerobic digesters to dry milling facilities, Phoenix BioSystems, provided information about its high-rate anaerobic digester, the Bio-Methanator. The 

Bio-Methanator is capable of reducing COD levels in dry milling wastewaters by 90 percent. 

According to Phoenix Bio-Systems, approximately 40 dry milling facilities currently use BioMethanators for their process wastewater (roughly 44 percent of dry milling facilities based on 

estimates described in Section 5.0), and this number is likely to double over the next few years 

(Holman, 2006c and 2006g; PBS, 2006). The majority of facilities that operate Bio-Methanators 

are “zero discharge” facilities, meaning they recycle virtually all of their wastewater. According 

to Phoenix Bio-Systems, the Bio-Methanator removes many of the organic acids produced 

during fermentation, such as acetic and lactic acids that can accumulate in recycle systems, 

inhibit the yeast in fermentation, and cause loss in ethanol yield. The removal of acid inhibitors 
Memorandum 

19 October 2006 

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11 

from process wastewater allows 100 percent recycle of the wastewater. Phoenix Bio-Systems 

indicated that dry milling facilities that do not operate Bio-Methanators or other anaerobic 

digesters may still recycle their process wastewater, but with a loss in yield. 

ERG contacted NPDES permit writers for Midwestern states that contain a significant number of 

ethanol production facilities to obtain wastewater information. ERG obtained the most detailed 

information from a Nebraska NPDES permit writer. This wastewater information on each 

ethanol production facility in the state (both wet and dry milling facilities) is summarized in 

Table 4-1. 

According to information obtained from the Nebraska NPDES permit writer and Phoenix BioSystems about the 10 dry milling facilities in Nebraska, the following wastewater systems are 

operated: 

 Three facilities operate Bio-Methanators (two of which recycle all process wastewater); 

 One operates an anaerobic cell; 

 One operates an aerobic activated sludge system; 

 One discharges process wastewater for off-site treatment; and 

 Four recycle all process wastewater (type of wastewater treatment is unknown). 

Of the dry milling facilities that discharge process wastewater, three discharge to POTWs and 

one discharges directly to surface waters. The majority of dry milling facilities discharge 

wastewater with low COD levels (relative to ethanol production), such as noncontact cooling 

water, cooling tower blowdown, and reverse osmosis reject water directly in accordance with 

NPDES permits. 

4.2 Wet Milling Facilities

As described in Section 3.2, wet milling facilities often treat their steepwater condensate in 

anaerobic systems followed by aerobic polishing systems. Wet milling facilities may treat the 

stillage (or processed stillage) from the ethanol fermentation/distillation process separately or 

together with steepwater and/or wash water. According to information obtained from various 

sources, wet milling facilities discharge their treated process waters directly to surface waters in 

accordance with NPDES permits or indirectly to publicly owned treatment works (POTWs) 

(Holman, 2006c and 2006e) (Ruocco, 2006b). See Table 4-1 for wastewater information on the 

two wet milling facilities in Nebraska. 

The types of wastewater treatment systems operated at wet milling facilities include: 

 Anaerobic cells; 

 Sequencing batch reactor (SBR) systems, which include anaerobic and aerobic stages; 

and 

 Activated sludge systems with aeration basins. 
Memorandum 

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Table 4-1. Ethanol Production Facilities in Nebraska

Facility Location Milling 

Treatment of 

Process Water Discharge to: Additional Info 

Abengoa 

Bioenergy 

York Dry Aerobic lagoon POTW Phoenix website (PBS, 2006) 

shows that this facility has a 

biomethanator, but doesn’t 

mention recycle of 

wastewater. NPDES permit 

for cooling water. 

AGP Hastings Dry Anaerobic cell 

(lined and covered) 

POTW CH4 is flared 

ADM Columbus Wet Anaerobic cells 

(lined and covered) 

followed by SBR 

(anaerobic and 

aerobic stage) 

Surface 

(NPDES) 

CH4 from anaerobic cells is 

used in boilers (emergency 

flare). CH4 is probably not 

recovered from SBR because 

the amount is not worth it. 

Aventine 

Renewable 

Energy 

Aurora Dry All process water recycled – 

zero discharge. Unknown if 

treated prior to recycle. 

Cargill Blair Wet SBR Surface 

(NPDES) 

CH4 is possibly flared 

Chief Ethanol Hastings Dry Activated sludge, 

traditional aerobic 

Surface 

(NPDES) for 

process water 

Cornhusker 

Energy 

Lexington Dry No on-site 

treatment 

City 

pretreatment 

then POTW 

Husker Ag Plainview Dry All process water recycled – 

zero discharge. BioMethanator and recycle (PBS, 

2006). Cooling water is land 

applied. 

KAAPA Minden Dry All process water recycled – 

zero discharge. BioMethanator and recycle (PBS, 

2006). Cooling water is land 

applied. 

Midwest 

Renewable 

Energy 

Sutherland Dry All process water recycled – 

zero discharge. Unknown if 

treated prior to recycle. 

Platte Valley 

Fuel Ethanol 

Central City Dry All process water recycled – 

zero discharge. Unknown if 

treated prior to recycle. 

Trenton Agri 

Products 

Trenton Dry All process water recycled – 

zero discharge. Unknown if 

treated prior to recycle. 

Source: (Holman, 2006e) and (PBS, 2006). 
Memorandum 

19 October 2006 

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4.3 CH4 Recovery and Use

The information ERG gathered on the ethanol industry indicates that the CH4 generated in 

anaerobic digesters is commonly collected and either flared or used as fuel in the ethanol 

production process. According to Phoenix Bio-Systems, almost all of the facilities operating 

Bio-Methanators collect the generated CH4 and use it to supplement the natural gas used to fuel 

boilers or DDG dryers. Phoenix Bio-Systems is aware of two facilities that do not use the CH4

generated, and these facilities flare the CH4 instead. (Holman, 2006c). Most commercial 

biomethanation systems contain emergency flare equipment that is intended to be used if biogas 

production exceeds requirements. (Merrick, 1998) 

NPDES permit writers for ethanol production facilities are not aware of any CH4 generated from 

anaerobic wastewater treatment at ethanol production facilities that is released to the atmosphere. 

Anaerobic lagoons are typically covered. The CH4 generated is used as fuel in the ethanol 

production process if economical, and if not, the CH4 is flared. (Holman, 2006a, 2006b, 2006e) 

One NPDES permit writer indicated that CH4 could potentially be released from the anaerobic 

portion of SBRs if these SBRs are downstream of other anaerobic systems. This may be due to 

the relatively small amount of CH4 generated in the anaerobic portion of these SBRs (Holman, 

2006e). 

One potential incentive for ethanol production facilities to recover CH4 generated from anaerobic 

wastewater treatment systems (in addition to using CH4 for fuel) involves Prevention of 

Significant Deterioration (PSD) permits. In order to avoid the requirement for these permits, 

facilities must emit less than 100 tons per year of volatile organic carbons (VOCs). Many 

ethanol production facilities are close to the 100 ton limit, and thus have incentive to recover 

CH4 generated from ethanol production wastewaters. (Holman, 2006h) 

4.4 Wastewater Characterization

Up to 20 liters of stillage may be generated for each liter of ethanol produced (Wilkie et al., 

2000). For corn milling ethanol production processes, stillage production is reported as 16.6 

liters of stillage per liter of ethanol produced. The concentration of COD in this stillage may be 

as high as 56 g/L based on published information from 1985 (Wilkie, 2000). In ethanol 

production processes that use cellulosic-based feedstock, the stillage may contain even higher 

organic load (Wilkie et al., 2000) (Merrick, 1998). A reported maximum for evaporator 

condensate (non-feedstock-specific) is 10 g/L (Wilkie et al., 2000). 

ERG obtained additional information specific to current dry milling operations. In dry milling 

facilities, the COD concentration of evaporator condensate is significantly lower than the stillage 

due to the removal of solids and solubles. The COD concentration of evaporator condensate 

wastewater from starch-based feedstock typically ranges from 1 to 5 g/L (Merrick, 1998). 

Based on data gathered in this study, the flow rate of process wastewater from dry milling 

facilities, which may include evaporator condensate, boiler blowdown, scrubber water, and CIP 

water, typically ranges from 25 to 400 gallons per minute (gpm) (Merrick, 1998) (PBS, 2006) 

(Holman, 2006e) (NE report) (Industrial WaterWorld). COD loadings typically range from 

2,000 to 16,000 pounds per day (ppd) (Ruocco, 2006a). 
Memorandum 

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The nutrient (nitrogen and phosphorus) content of ethanol production wastewaters has been 

reported to be relatively low, with the exception of stillage generated from barley feedstock 

(Wilkie et al, 2000) (Holman, 2006g). Nutrient addition may be required for the proper growth 

of microorganisms in activated sludge systems treating ethanol production wastewaters (U.S. 

EPA, 1986). 

5.0 GHG EMISSIONS ESTIMATES

From the information obtained in this study and described in previous sections, ERG estimated 

the potential GHG emissions from the ethanol production industry. This section provides the 

methodology for the emission calculations, along with descriptions of the assumptions. The 

assumptions made for these estimations fall under three categories: assumptions for the overall 

process; assumptions for dry milling; and assumptions for wet milling. 

5.1 Emission Calculation Methodology

ERG calculates the GHG emissions from the ethanol production industry as follows: 

Total Industry 

 CH4 emissions = Dry milling CH4 emissions + Wet milling CH4 emissions 

Dry Milling 

CH4 emissions = CH4 emissions for facilities with Bio-Methanators (BM) + CH4 

emissions for facilities with other anaerobic treatment (AT) 

CH4 emissions for BM = #Facilities * Flow * COD concentration * %BM * EF 

Where: 

#Facilities = 91 

Flow = 400 gpm (PBS, 2006) (Merrick, 1998) (Ruocco, 2006a) 

COD concentration = 3 g/L (Merrick, 1998) 

%BM = 44% (see Table 5-1) 

Emission Factor (EF) (BM) = CH4 yield / COD loading (published data) (Merrick, 1998) 

CH4 emissions for AT = #Facilities * Flow * COD concentration * %AT * EF 

Where: 

#Facilities = 91 

Flow = 400 gpm (PBS, 2006) (Merrick, 1998) (Ruocco, 2006a) 

COD concentration = 3 g/L (Merrick, 1998) 

%AT = (50% of (#Facilities - #Facilities * %BM)) 

EF (Generic AT) = Bo * MCF 

Bo = 0.25 
Memorandum 

19 October 2006 

Page 15 

15 

MCF = 0.8 

Wet Milling 

CH4 emissions = CH4 emissions for steepwater + CH4 emissions for stillage 

CH4 emissions for steepwater = #Facilities * COD loading * %AT * EF 

Where: 

#Facilities = 10 (see Table A-1 for sources) 

COD Loading = 100,000 ppd (Ruocco, 2006b) 

%AT = 66.6% (see Table 5-2) 

EF (Generic AT) = Bo * MCF 

Bo = 0.25 

MCF = 0.8 

CH4 emissions for stillage = 10% * Dry milling COD loading * EF 

Where: 

EF (Generic AT) = Bo * MCF 

Bo = 0.25 

MCF = 0.8 

5.2 Explanation of Assumptions

ERG made the following assumptions for the overall process: 

 ERG only included data related to the corn-based process, the focus of this memorandum, 

as described in Section 2.0. 

 ERG assumes that the only GHG emitted from the ethanol production industry is CH4

and the only emissions source is anaerobic wastewater treatment systems. The only 

information obtained in this study about nitrification/denitrification systems indicates that 

they are not likely operated at ethanol production facilities. (Holman, 2006a – 2006h) 

ERG assumes that GHG are not emitted from wastewater treatment system sludge or 

stormwater runoff. 

ERG made the following assumptions for the dry milling calculations: 

 Based on the current RFA count of 101 ethanol facilities in operation and the assumption 

that there are 10 wet milling facilities currently in operation (see wet milling 

assumptions), ERG estimates that there are currently 91 dry milling facilities in 

operation. 
Memorandum 

19 October 2006 

Page 16 

16 

 The RFA lists 43 ethanol facilities under construction or expanding and based on 

information received [ref], ERG expects that these are all dry milling facilities. ERG did 

not include the construction/expansion production in its calculations. 

 ERG used an evaporator condensate flow rate of 400 gpm (PBS, 2006) (Merrick, 1998) 

(Ruocco, 2006a) and a COD concentration of 3 g/L, which is the midpoint of a range of 1 

to 5 g/L (Merrick, 1998). This equates to over 14,000 ppd of COD, which is the high end 

of the range reported by Ruocco (2006a). 

 The estimated number of dry milling facilities operating Bio-Methanators is discussed in 

Section 4.1. ERG calculated an emissions factor for Bio-Methanator units based on 

example bio-gas production and CH4 yield data supplied by Phoenix Bio-Systems in a 

published report (Merrick, 1998). 

 ERG assumed a percentage of anaerobic treatment based on information received from 

various sources. The dry milling assumptions are summarized in Table 5-1. 

Table 5-1. Assumptions for Dry Milling Calculations 

Percentage 

of 

Facilities 

Number 

of 

Facilities 

Dry Milling Facilities in Ethanol Production Industry 100% 91 

Dry Milling Facilities that Operate Bio-Methanators 44% 40 

Remaining Dry Milling Facilities that Operate Other Types 

of Anaerobic Systems 

50% 25.5 

Remaining Dry Milling Facilities that Operate Aerobic 

Activated Sludge Systems or No Wastewater Treatment 

50% 25.5 

Source: (Holman, 2006a – 2006g); see Table A-1 for listing of dry milling facilities. 

ERG made the following assumptions for the wet milling calculations: 

 ERG determined that there are currently 10 wet milling facilities in the ethanol 

production industry based on a variety of published information and personal 

communications (ref). These 10 facilities account for approximately 25 percent of the 

current ethanol production capacity. 

 From information obtained from permit writers (see Table 4-1), ERG assumes that onethird of wet milling facilities operate SBRs, one-third operate anaerobic lagoons 

(covered) followed by SBRs, and the remaining one-third operate aerobic activated 

sludge systems. Table 5-2 summarizes the wet milling assumptions. 
Memorandum 

19 October 2006 

Page 17 

17 

Table 5-2. Assumptions for Wet Milling Calculations 

Percentage 

of 

Facilities 

Number 

of 

Facilities 

Wet Milling Facilities in Ethanol Production Industry 100% 10 

Wet Milling Facilities that Operate SBRs 33.3% 3.33 

Wet Milling Facilities that Operate Anaerobic Lagoons 

(covered) followed by SBRs 33.3% 3.33 

Wet Milling Facilities that Operate Aerobic Activated 

Sludge Systems 33.3% 3.33 

Source: (Holman, 2006a – 2006g); see Table A-1 for listing of wet milling facilities. 

5.3 Preliminary Estimates of GHG Emissions

Given all of the assumptions described in Sections 5.2 through 5.4, ERG estimates that the total 

potential GHG emissions from the ethanol industry is 55.2 Gg/year of CH4 or 1.16 Tg-CO2

equivalent/year (realistic case). Table 5-2 includes a comparison of worst case and realistic case 

GHG emissions. 

Table 5-2. GHG Emissions Estimates for 2006 

Realistic Estimatea

(CH4 Gg/year) 

Realistic Estimatea

(Tg-CO2

equivalent/year) 

Worst Case 

Estimateb

(CH4 Gg/year) 

Worst Case 

Estimateb

(Tg-CO2

equivalent/year) 

Dry Milling Facilities 30.0 0.631 72.4 1.52 

Wet Milling Facilities 25.2 0.529 40.4 0.85 

Total Ethanol 

Production Industry 55.2 1.16 113 2.37 

a – No CH4 recovery 

b – 100% anaerobic treatment, no CH4 recovery, and high end of COD concentration (5 g/L) 

The realistic case may be overestimated to some extent (possibly to a large extent) for the 

following reasons: 

 ERG has obtained information indicating that at least a portion of ethanol production 

facilities recover CH4 generated from anaerobic treatment systems. 

 For the dry and wet milling calculations, ERG used the high end of the COD loading 

ranges obtained. 

The realistic case may be slightly overestimated or underestimated based on the following 

reasons: 
Memorandum 

19 October 2006 

Page 18 

18 

 ERG has not obtained sufficient wastewater information for the wet milling process such 

as typical percentage of wastewater recycle and typical treatment of stillage from the 

ethanol fermentation/distillation process. 

 ERG has obtained information from various sources that substantiates the assumption 

that some ethanol production facilities do not treat their process wastewater 

anaerobically, and thus substantiates the decrease from the worst case to the realistic 

case; however, ERG does not know the actual percentage of anaerobic treatment. 

 ERG did not perform a thorough investigation of potential GHG emissions from 

nitrification/denitrification processes and/or sludge or stormwater runoff. However, ERG 

did not obtain any information that indicates potential for GHG emissions from these 

sources. 

 

6.0 NEXT STEPS

The preliminary estimate of emissions presented in this memorandum is developed on a per plant 

basis, dependent on whether the plant conducts wet or dry milling. If EPA determines this 

source is of interest for inclusion in the inventory, ERG recommends that the calculation method 

be revised to estimate emissions based on production. Sufficient data exist to calculate dry 

milling emissions based on production, but additional data are needed for wet milling operations, 

including data to relate the wastewater COD load to ethanol production. In addition, because the 

type and amount of co-products produced at wet milling facilities significantly affects the 

wastewater flows and COD loads, co-production data would also need to be obtained. If this 

data can be obtained and the wet milling wastewater COD load can be related to production, 

ERG can produce an estimate of emissions for the inventory time series. 

ERG also recommends collecting additional data on wet milling operations, including typical 

flow rates and stillage handling processes, to better profile current operations and treatment, as 

well as additional data to quantify the amount of wastewater recycled at wet and dry milling 

operations, which could affect the amount of wastewater that is treated anaerobically. Data 

collection activities could also address greenhouse gas emissions from sludge handling, storm 

water runoff, and nitrificiation/denitrification systems. 

These data may be obtained through further conversations with NPDES permit writers, 

pretreatment coordinators, and ethanol production facilities. To date, ERG has limited contacts 

to those readily available through e-mail and telephone contacts. ERG could also obtain permits 

for review of plant operations, but has found that the likelihood of locating information useful to 

this analysis, compared to the effort in obtaining the permit, may be low. 

In addition, ERG recommends further work to determine the extent to which CH4 is recovered at 

both wet and dry milling ethanol production facilities. ERG believes additional contacts within 

EPA’s Office of Air would supplement information regarding potential incentives to recover 

emissions (including CH4) and any studies on air emissions from ethanol production wastewater 

treatment operations. 
Memorandum 

19 October 2006 

Page 19 

19 

7.0 REFERENCES

EIA. 2005. U.S. Department of Energy – Energy Information Administration (EIA). Renewable 

Fuels Legislation Impact Analysis. (July). Available online at: 

http://tonto.eia.doe.gov/FTPROOT/service/s606_s650_analysis.pdf. Date 

Accessed: October, 2006. 

EIA. 2006. U.S. Department of Energy – Energy Information Administration (EIA). Annual 

Energy Outlook 2006 with Projections to 2030. DOE/EIA-0383(2006). 

(February). Available online at: http://www.eia.doe.gov/oiaf/aeo/gas.html. Date 

Accessed: October, 2006. 

Holman. 2006a. Telephone conversation with Steven Williams of the Iowa Department of 

Natural Resources, Wastewater Division, NPDES Permits and Sarah Holman of 

ERG. “Ethanol Production Facilities – VeraSun Energy Corp., NPDES ID No. 

IA0079227.” (August 31). 

Holman. 2006b. Telephone conversation with Kelly Buscher of the South Dakota Department 

of Environment and Natural Resources, Surface Water Discharge Permits and 

Sarah Holman of ERG. “South Dakota Ethanol Production Facilities – Dakota 

Ethanol, NPDES ID No. SD0027847.” (September 1). 

Holman. 2006c. Telephone conversation with Dr. Joe Ruocco of Phoenix Bio-Systems and 

Sarah Holman of ERG. “Bio-Methanator Units at Ethanol Production Facilities.” 

(September 5). 

Holman. 2006d. Telephone conversation with Peggi Badten of the City of Aberdeen, South 

Dakota and Sarah Holman of ERG. “South Dakota Ethanol Production Facilities 

– Heartland Grain Fuels, LP.” (September 6). 

Holman. 2006e. Telephone conversation with Ron Ash of Nebraska Department of 

Environmental Quality, Water Division, NPDES Program and Sarah Holman of 

ERG. “Nebraska Ethanol Production Facilities – Chief Ethanol, NPDES ID No. 

NE0114243.” (September 7). 

Holman. 2006f. Telephone conversation with Matt Gluckman of U.S. EPA, Region 5, WN-16J 

and Sarah Holman of ERG. “Region 5 Ethanol Production Facilities – New 

Energy Corp. and MGPI.” (September 19). 

Holman. 2006g. Telephone conversation with Dr. Ann Wilkie of University of Florida, Soil and 

Water Science Department and Sarah Holman of ERG. “Wastewater stillage 

from ethanol production facilities.” (September 20). 

Holman. 2006h. Telephone conversation with Mike Pring of ERG and Sarah Holman of ERG. 

“Emissions from ethanol production facilities.” (September 7). 
Memorandum 

19 October 2006 

Page 20 

20 

ICGA. 2006. Iowa Corn Growers Association. Co-Products from the Ethanol Industry. (June 

5). Available online at: 

http://www.iowabeefcenter.org/content/BECTextor.pdf#search=%22wet%20milli

ng%20ddg%22. Date Accessed: October, 2006. 

IDED. 2004. Iowa Department of Economic Development. Ethanol Flows from Iowa’s Big 

River Resources. Available online at: 

http://www.iowalifechanging.com/business/downloads/bsethanol.pdf. Date 

Accessed: October, 2006. 

IEPA. 2006. Illinois Environmental Protection Agency. Summary Information on Fuel Ethanol 

Plants in Illinois. Available online at: 

http://www.epa.state.il.us/air/permits/ethanol-plants.html. Date Updated: October 

6, 2006. Date Accessed: October, 2006. 

Lalley, Mary. 2002. ERG. Memorandum to Bob Rosensteel, U.S. EPA. “Ethanol Production 

Industry.” (July 2). 

LBNL. 2003. Lawrence Berkeley National Laboratory (LBNL). Energy Efficiency 

Improvement and Cost Saving Opportunities for the Corn Wet Milling Industry:

An ENERGY STAR® Guide for Energy and Plant Managers. LBNL-52307. 

(July). Available online at: http://ies.lbl.gov/iespubs/52307.pdf. Date Accessed: 

October, 2006. 

Mannsville Chemical. 1998. Mannsville Chemical Products Corporation. Chemical Products 

Synopsis: Ethanol. Adams, NY. (August). 

Merrick. 1998. Merrick & Company. Wastewater Treatment Options for the Biomass-toEthanol Process. Report presented to National Renewable Energy Laboratory 

(NREL). Subcontract No. AXE-8-18020-01. (October 22). 

 

MPCA. 2002. Minnesota Pollution Control Agency (MPCA). Ethanol Production in 

Minnesota. (October). Available online at: 

http://www.pca.state.mn.us/publications/aq1-20.pdf. Date Accessed: October, 

2006. 

NDEQ. 2006. Nebraska Department of Environmental Quality. Air Quality and Ethanol 

Production: Nebraska’s Experience. (February). Available online at: 

http://www.deq.state.ne.us/Publica.nsf/23e5e39594c064ee852564ae004fa010/ebc

80085fd2df8b705256c75005885eb/$FILE/NDEQEthanolupdate06.pdf. Date 

Accessed: October, 2006. 

NEB. 2006. Nebraska Ethanol Board. Nebraska Ethanol Plants. Available online at: 

http://www.ne-ethanol.org/industry/ne_ethanolplants2006.pdf. Date Accessed: 

October, 2006. 
Memorandum 

19 October 2006 

Page 21 

21 

PBS. 2006. Phoenix Bio-Systems (PBS). General Project Experience: Anaerobic. Available 

online at: http://www.pbiosystems.com/experience.htm. Date Accessed: October, 

2006. 

Rausch, et al. 2006. “The Future of Coproducts from Corn Processing.” Applied Biochemistry 

and Biotechnology. 128: 47-86. Available online at: http://www.agbioeng.uiuc.edu/fbe/FBE%20web%20downloads/The%20future%20of%20copro

ducts%20from%20corn%20processing.pdf. Date Accessed: October, 2006. 

RFA. 2006a. Renewable Fuels Association (RFA). Ethanol Biorefinery Locations. Available 

online at: http://www.ethanolrfa.org/industry/locations/. Date Accessed: July, 

2006. 

RFA. 2006b. Renewable Fuels Association (RFA). From Niche to Nation: Ethanol Industry 

Outlook 2006. (February). Available online at: 

http://www.ethanolrfa.org/objects/pdf/outlook/outlook_2006.pdf#search='From%

20Niche%20to%20Nation%3A%20Ethanol%20Industry%20Outlook%202006'. 

Date Accessed: October, 2006. 

RFA. 2006c. Renewable Fuels Association (RFA). Industry Statistics. Available online at: 

http://www.ethanolrfa.org/industry/statistics/#A. Date Accessed: October, 2006. 

Ruocco, Joe. 2006a. Email from Dr. Joe Ruocco of Phoenix Bio-Systems to Sarah Holman of 

ERG. “Capacity of Bio-Methanators (Dry Milling).” (October 6). 

Ruocco, Joe. 2006b. Email from Dr. Joe Ruocco of Phoenix Bio-Systems to Sarah Holman of 

ERG. “Capacity of Bio-Methanators (Wet Milling).” (October 16). 

USDA. 2005. United States Department of Agriculture (USDA). Office of Energy Policy and 

New Uses. USDA’s 2002 Ethanol Cost-of-Production Survey. Agricultural 

Economic Report Number 841. (July). 

U.S. EPA. 1986. Office of Water. Multimedia Technical Support Document for the Ethanolfor-Fuel Industry. EPA 440/1-86/093. (April). 

U.S. EPA. 2006. Office of Transportation and Air Quality. Regulatory Announcement: 

Removal of Reformulated Gasoline Oxygen Content Requirement. EPA420-F-06-

035. (May). 

VeraSun. 2006. VeraSun Energy Corporation. Facilities. Available online at: 

http://www.verasun.com/facilities/. Date Accessed: October, 2006. 

Wilkie, et al. 2000. “Stillage Characterization and Anaerobic Treatment of Ethanol Stillage 

from Conventional and Cellulosic Feedstocks.” Biomass and Bioenergy. 19: 63-

102. 

 
22 

Appendix A 

U.S. ETHANOL PRODUCTION FACILITIES 
A-1

Table A-1. U.S. Ethanol Production Facilities 

Company Location City 

Location 

State Feedstock 

Current 

Capacity 

(MGY) 

Under 

Construction/

Expanding 

(MGY) 

Pinal Energy, LLC Maricopa AZ Corn 55 

Golden Cheese Company of 

Californiaa

Corona CA Cheese whey 5 

Pacific Ethanol Madera CA Corn 35 

Parallel Productsb R. Cucamonga CA Beverage waste 3 

Phoenix Biofuels Goshen CA Corn 25 

Front Range Energy, LLC Windsor CO Corn 40 

Merrick/Coors Golden CO Waste beer 1.5 1.5 

Sterling Ethanol, LLC Sterling CO Corn 42 

Wind Gap Farms Baconton GA Brewery waste 0.4 

Amaizing Energy, LLCa Denison IA Corn 40 

Archer Daniels Midlandc,d Cedar Rapids IA Corn 200 

Archer Daniels Midlandc,d Clinton IA Corn 200 

Big River Resources, LLCa West Burlington IA Corn 40 

Cargill, Inc.d Eddyville IA Corn 35 

Corn, LPa Goldfield IA Corn 50 

Frontier Ethanol, LLC Gowrie IA Corn 60 

Global Ethanol/Midwest Grain 

Processors 

Lakota IA Corn 95 

Golden Grain Energy, LLCa Mason City IA Corn 60 50 

Grain Processing Corp.d Muscatine IA Corn 20 

Green Plains Renewable Energy Shenandoah IA Corn 50 

Hawkeye Renewables, LLC Iowa Falls IA Corn 100 

Hawkeye Renewables, LLC Fairbank IA Corn 100 

Horizon Ethanol, LLC Jewell IA Corn 60 

Iowa Ethanol, LLCa Hanlontown IA Corn 50 

Lincolnway Energy, LLCa Nevada IA Corn 50 

Little Sioux Corn Processors, 

LPa

Marcus IA Corn 52 

Otter Creek Ethanol, LLCa Ashton IA Corn 55 

Permeate Refining Hopkinton IA Sugars & 

starches 

1.5 

Pine Lake Corn Processors, 

LLCa

Steamboat Rock IA Corn 20 

Pinnacle Ethanol, LLC Corning IA Corn 60 
Table A-1 (Continued) 

A-2

Company Location City 

Location 

State Feedstock 

Current 

Capacity 

(MGY) 

Under 

Construction/

Expanding 

(MGY) 

Quad-County Corn Processorsa Galva IA Corn 27 

Siouxland Energy & Livestock 

Coopa

Sioux Center IA Corn 25 10 

Tall Corn Ethanol, LLCa Coon Rapids IA Corn 49 

US BioEnergy Corp. Albert City IA Corn 100 

VeraSun Energy Corporatione Ft. Dodge IA Corn 120 

VeraSun Energy Corporatione Charles City IA Corn 110 

Voyager Ethanol, LLCa Emmetsburg IA Corn 52 

Xethanol BioFuels, LLC Blairstown IA Corn 5 

Adkins Energy, LLCa Lena IL Corn 40 

Archer Daniels Midlandc Peoria IL Corn 100 

Archer Daniels Midlandc,d Decatur IL Corn 290 

Aventine Renewable Energy, 

LLCd

Pekin IL Corn 100 57 

Illinois River Energy, LLC Rochelle IL Corn 50 

Lincolnland Agri-Energy, LLCa Palestine IL Corn 48 

MGP Ingredients, Inc.b Pekin IL Corn/wheat 

starch 

39 

ASAlliances Biofuels, LLC Linden IN Corn 100 

Central Indiana Ethanol, LLC Marion IN Corn 40 

Iroquois Bio-Energy Company, 

LLC 

Rensselaer IN Corn 40 

New Energy Corp. South Bend IN Corn 102 

The Andersons Clymers Ethanol, 

LLC 

Clymers IN Corn 110 

Abengoa Bioenergy Corp. Colwich KS Corn/milo 25 

Conestoga Energy Partners Garden City KS Corn/milo 55 

East Kansas Agri-Energy, LLCa Garnett KS Corn 35 

ESE Alcohol Inc. Leoti KS Seed corn 1.5 

MGP Ingredients, Inc.b Atchison KS Corn/wheat 

starch 

6 

Prairie Horizon Agri-Energy, 

LLC 

Phillipsburg KS Corn 40 

Reeve Agri-Energy Garden City KS Corn/milo 12 

U.S. Energy Partners, LLC 

(White Energy) 

Russell KS Milo/wheat 

starch 

48 

Western Plains Energy, LLCa Campus KS Corn 45 
Table A-1 (Continued) 

A-3

Company Location City 

Location 

State Feedstock 

Current 

Capacity 

(MGY) 

Under 

Construction/

Expanding 

(MGY) 

Commonwealth Agri-Energy, 

LLCa

Hopkinsville KY Corn 33 

Parallel Productsb Louisville KY Beverage waste 2.4 

Global Ethanol/Midwest Grain 

Processors 

Riga MI Corn 57 

Michigan Ethanol, LLC Caro MI Corn 50 

The Andersons Albion Ethanol 

LLC 

Albion MI Corn 55 

US BioEnergy Corp. Lake Odessa MI Corn 45 

Agra Resources Coop. d.b.a. 

EXOLa

Albert Lea MN Corn 40 8 

Agri-Energy, LLCa Luverne MN Corn 21 

Al-Corn Clean Fuela Claremont MN Corn 35 

Archer Daniels Midlandc,d Marshall MN Corn 40 

Bushmills Ethanol, Inc.a Atwater MN Corn 40 

Central MN Ethanol Coopa Little Falls MN Corn 21.5 

Chippewa Valley Ethanol Co.a Benson MN Corn 45 

Corn Plus, LLPa Winnebago MN Corn 44 

DENCO, LLCa Morris MN Corn 21.5 

Ethanol2000, LLPa Bingham Lake MN Corn 32 

Granite Falls Energy, LLC Granite Falls MN Corn 45 

Heartland Corn Productsa Winthrop MN Corn 36 

Heron Lake BioEnergy, LLC Heron Lake MN Corn 50 

Land O' Lakesa,d Melrose MN Cheese whey 2.6 

Minnesota Energya Buffalo Lake MN Corn 18 

Northstar Ethanol, LLC Lake Crystal MN Corn 52 

Pro-Corn, LLCa Preston MN Corn 42 

Golden Triangle Energy, LLCa Craig MO Corn 20 

Mid-Missouri Energy, Inc.a Malta Bend MO Corn 45 

Missouri Ethanol Laddonia MO Corn 45 

Northeast Missouri Grain, LLCa Macon MO Corn 45 

Alchem Ltd. LLLP Grafton ND Corn 10.5 

Archer Daniels Midlandc Wallhalla ND Corn/barley 28 

Blue Flint Ethanol Underwood ND Corn 50 

Red Trail Energy, LLC Richardton ND Corn 50 

Abengoa Bioenergy Corp. Ravenna NE Corn/milo 88 
Table A-1 (Continued) 

A-4

Company Location City 

Location 

State Feedstock 

Current 

Capacity 

(MGY) 

Under 

Construction/

Expanding 

(MGY) 

Abengoa Bioenergy Corp. York NE Corn/milo 55 

Advanced Bioenergy Fairmont NE Corn 100 

AGPa Hastings NE Corn 52 

Archer Daniels Midlandc,d Columbus NE Corn 245 

ASAlliances Biofuels, LLC Albion NE Corn 100 

Aventine Renewable Energy, 

LLC 

Aurora NE Corn 50 

Cargill, Inc.d Blair NE Corn 85 

Chief Ethanol Hastings NE Corn 62 

Cornhusker Energy Lexington, 

LLC 

Lexington NE Corn 40 

E3 Biofuels Mead NE Corn 24 

Husker Ag, LLCa Plainview NE Corn 26.5 

KAAPA Ethanol, LLCa Minden NE Corn 40 

Mid America Agri 

Products/Wheatland 

Madrid NE Corn 44 

Midwest Renewable Energy, 

LLC 

Sutherland NE Corn 25 

Platte Valley Fuel Ethanol, 

LLCc 

Central City NE Corn 40 

Siouxland Ethanol, LLC Jackson NE Corn 50 

Trenton Agri Products, LLC Trenton NE Corn 35 10 

Val-E Ethanol, LLC Ord NE Corn 45 

Abengoa Bioenergy Corp. Portales NM Corn/milo 30 

ASAlliances Biofuels, LLC Bloomingburg OH Corn 100 

Liquid Resources of Ohio Medina OH Waste 

Beverage 

3 

Cascade Grain Clatskanie OR Corn 108 

Broin Enterprises, Inc. Scotland SD Corn 9 

Dakota Ethanol, LLCa Wentworth SD Corn 50 

Glacial Lakes Energy, LLCa Watertown SD Corn 50 

Great Plains Ethanol, LLCa Chancellor SD Corn 50 

Heartland Grain Fuels, LPa Aberdeen SD Corn 9 

Heartland Grain Fuels, LPa Huron SD Corn 12 18 

James Valley Ethanol, LLC Groton SD Corn 50 

Millennium Ethanol Marion SD Corn 100 

North Country Ethanol, LLCa Rosholt SD Corn 20 
Table A-1 (Continued) 

A-5

Company Location City 

Location 

State Feedstock 

Current 

Capacity 

(MGY) 

Under 

Construction/

Expanding 

(MGY) 

Northern Lights Ethanol, LLCa Big Stone City SD Corn 50 

Prairie Ethanol, LLC Loomis SD Corn 60 

Redfield Energy, LLC Redfield SD Corn 50 

Sioux River Ethanol, LLCa Hudson SD Corn 55 

VeraSun Energy Corporatione Aurora SD Corn 120 

Tate & Lyle Loudon TN Corn 67 

Panhandle Energies of Dumas, 

LP 

Dumas TX Corn/Grain Sorghum 30 

White Energy Hereford TX Corn/Milo 100 

ACE Ethanol, LLC Stanley WI Corn 39 

Badger State Ethanol, LLCa Monroe WI Corn 48 

Central Wisconsin Alcohol Plover WI Seed corn 4 

United WI Grain Producers, 

LLCa

Friesland WI Corn 49 

Utica Energy, LLC Oshkosh WI Corn 48 

Western Wisconsin Renewable 

Energy, LLCa

Boyceville WI Corn 40 

Wyoming Ethanol Torrington WY Corn 5 

Total Current Capacity 4817.9 

Total Under Construction (36)/Expansions (7) 2430.5 

Total Capacity 7248.4 

Source: (RFA, 2006a) 

a – Farmer-owned 

b – Data obtained at (NEB, 2006) for individual facilities. 

c – Additional capacity, indicated from total Archer Daniels Midland capacity (RFA, 2006a), added to the Columbus, NE 

facility due to possible expansion. Sources: (IDED, 2004), (MPCA, 2002), (NDEQ, 2006), (IEPA, 2006), (NEB, 2006), 

(ICGA, 2006). 

d – Wet milling facilities. Sources: (ICGA, 2006), (IDED, 2004), (IEPA, 2006), (LBNL, 2003), (MPCA, 2002), (NDEQ, 

2006), (NEB, 2006). 

e – Data obtained at (Verasun, 2006) for VeraSun individual plants.