## MEMORANDUM

TO: Melissa Weitz, EPA

FROM: Deb Bartram and Sarah Holman, ERG

DATE: 19 October 2006

SUBJECT: Assessment of Greenhouse Gas Emissi ons from Wastewater Treatment of U.S. Ethanol Production Wastewaters

As directed by EPA, ERG is s upporting the identification of im provements 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 faci lities. This memorandum also includes a list of potential next steps to further investigate this industry segment.

1.0 I NTRODUCTION



### Wastewater treatment processes ca n produce anthropogenic methane (CH 4 

### ) and nitrous oxide (N 2 

### O) emissions. Wastewater from industrial sour ces is typically treated to remove soluble organic matter, suspended solids, pathogenic orga nisms, and chemical contaminants. Soluble organic matter is generally removed using bi ological 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 materi al in wastewater under aerobi c or anaerobic conditions, where the latter condition produces CH 4


### .
The generation of N 2 

### O 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 (NO 3 

### ) through the aerobic process of nitrification. Denitrification occurs under a noxic conditions (without free oxyge n), and involves the biological conversion of nitrate into dinitrogen gas (N2). N 2 

### O can be an intermediate product of both processes, but is more often a ssociated with denitrification.

In this memorandum, ERG presents a summary of U.S. ethanol production operations, including the types of wastewaters generate d and the types of wastewater tr eatment 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 Page 2

2 2.0 O VERVIEW OF 

### E THANOL 

### I NDUSTRY



### Ethanol, or ethyl alcohol, is produ ced primarily for use as a fuel component, but is also used in industrial applications an d in the manufacture of beverage alco hol. Ethanol is used industrially in solvents, thinners, detergents , toiletries, cosmetics, rubbing al cohol, pharmaceuticals, and the synthesis of chemical intermediates (e.g., ethylen e glycol). In 1997, the fuel demand for ethanol was approximately five times greater than the in dustrial 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 pe rcent 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, et hanol has been used increasingly as an octane enhancer and oxygenate in gasoli ne. Section 211(k) of the 1990 Amendments to the Clean Air Act mandated that gasoline sold in geographic areas with a certain le vel 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 ofthe ethanol produced in 2004 was used in oxygenmandated areas including California, New Yor k, Connecticut, Illinois (Chicago), Wisconsin (Milwaukee), and Minnesota. The remaining 20 pe rcent was used to increase the octane rating in gasoline across the United States (USDA, 2005).

Despite the remand of the oxygen requirement, etha nol production is expected to continue to increase, due in part to EPACT 2005, which created a national Rene wable 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). Additi onally, 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) exp ects that refiners will stop ble nding MTBE by 2008 due to groundwater contamination concerns, and refiners w ill continue to blend ethanol (EIA, 2006).

Appendix A contains the Renewa ble Fuel Association (RFA) lis ting of U.S. ethanol production facilities (both currently opera ting and under construc tion), locations, feedstocks, and production capacities. Ethanol production fac ilities 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 Page 3

3 of 2006, ethanol production capacity was 4,818 m illion gallons per year (MGY) and the additional capacity from facilities under cons truction or expanding produ ction was 2,431 MGY. The individual facility ethanol production capacity ranges fr om 0.4 MGY to 290 MGY. (RFA, 2006a) Over the past eight years, ethanol pr oduction 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. P roduction 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 Capacity a (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-base d feedstocks (e.g., corn, sorghum , and beverage waste), and cellulosic biomass feedstocks (e .g., agricultural wastes, wood, and ba gasse). Ethanol can also be produced synthetically from ethylene or hydr ogen 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) (Mannsvill e Chemical, 1998). Table 2-3 contains a timeline of synthetic and fermenta tion ethanol production. Using the 1997 synthetic ethanol production number, which remained roughly stable for about 12 years, the 2006 percentage of synthetic etha nol 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 etha nol production will reach 25 to 830 million gallons per year by 2025, depending on the case, as show n in Figure 2-1 (EIA, 2005). However, cellulosic biomass ethanol production is currently in an experi mental stage in the United States, and thus, is not discussed furt her in this memorandum.

### Memorandum 19 October 2006 Page 4

4 Figure 2-1. EIA Projections of Ethanol Production Source: National Energy Modeling System (EIA, 2006)



### The fermentation of corn is the principal etha nol 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 oxygena te 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 pr ojects 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 produc tion 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); wh eat; and sugars. (RFA, 2006a) Figure 2-2 depicts the distribution of production methods in use in the U.S.

### Memorandum 19 October 2006 Page 5

5 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 S TARCH



### - BASED 

### E THANOL 

### P RODUCTION 

### P ROCESSES



### Because the fermentation of corn is the principa l 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 etha nol 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, th e 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 init ial treatment of feedstock and the co-product production process. Wet milling facilities genera te 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-pr oduct: distillers’ dried grains with solubles (DDGS).

Historically, the majority of ethanol was pr oduced 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 f acilities went out of business in the 1980s due to inefficiency, and were replaced by larger a nd more efficient dry milling facilities. Because wet milling facilities are more equipment and capita l 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 m illing 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 Page 6

6  Milling (grinding);

 Cooking/Liquefaction;

 Saccharification/Fermentation;

 Distillation;

 Dehydration;

 Denaturing; and

 Co-products processing.

In the milling stage, corn kernels are ground in to flour, or “meal”, and processed without separating out the kernel’s component parts. In th e 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 s accharification 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 (CO 2 

### ) exothermically. This CO 2 

### is typically captured and sold for use in carbonated beverages and the manufacture of dry ice. During fermenta tion, 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 di stillation 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., ga soline) to render it undr inkable 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 result ing liquid is referred to as “thin” stillage. Thin stillage may be processe d through an evaporation st age, which serves to reduce wastewater output and produ ce syrup. This syrup may be dried to produce distillers dried solubles (DDS), which is sold as feed and/or fe rtilizer. The syrup from evaporation may also be added to the solids from mechanical separati on, creating distillers wet grains (DWG). DWG may be dried to produce distillers dried grains with solubles (DDG S), which is sold as livestock feed. Other thin stillage processing technique s that are still developing in the United States include single cell protein produc tion and membrane separation, which similarly result in feed and/or fertilizer (Wilk ie et al., 2000).

### Memorandum 19 October 2006 Page 7

Milling (Grinding )

Dehydration Distillation Saccharification/

Fermentation

Cooking/ Liquefaction

Denaturing Solids Separation Evaporation

Drying Drying Corn (or other starch-based

feedstock)

Alphaamylase

Water

Ammonia

Glucoamylase CO 2

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 19 October 2006 Page 8

8 3.1.2 Wastewaters from Dry Milling Process

Process was tewaters generated from the dry milling ethanol production process, which are depicted in Figure 3-1, include the following:

 Evaporator condensate (wastewater fr om 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. Evapor ator condensate and other wastewaters listed above are often commingled and recycled and/ or treated on site in anaerobic wastewater treatment systems. Other wast ewaters that are typi cally handled separately are noncontact cooling water, cooling tower blowdown, a nd reverse osmosis reject water.

It is common practice at dry milling facilities, part icularly at new dry milling facilities, to recycle portions of the whole stillage, th in stillage, and/or evaporator condensate back to the ethanol production process, typically to the cooking stage. Many relative ly new dry milling facilities are considered “zero discharge” and recycle virtua lly all of their process wastewaters [many references]. Some facilities treat the process wast ewater prior to recycle. Recycling and on-site treatment operations are discu ssed 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 m illing 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 throu gh a series of grinders to loosen th e oil-containing ge rm. The corn oil from the germ may be extracted on site or the ge rm may be sold. The remaining fiber, gluten, and starch components are further segregated using centrifugal, sc reen, and hydroclonic separators. The fiber is processe d into a wet feed product and the gl uten is filtered and dried to produce a protein meal feed ingredient. The star ch can be processed in three ways: dried and sold as dried or modified corn starch; processe d 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 Page 9

9 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 Dioxide Water

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 pe rcent solids), which is dried to produce corn

### Memorandum 19 October 2006 Page 10

10 gluten feed (CGF). The steepwater condensate fro m evaporation is typically treated on site in anaerobic systems (e.g., anaerob ic lagoons) followed by aerobic polishing systems (Ruocco, 2006b) (Rausch, 2006).

Wet milling facilities may handle the whole stilla ge from ethanol production in a variety of ways. ERG obtained some information indicatin g that wet milling facilities typically do not produce co-products from whole stillage and, instea d, discharge the whole s tillage as wastewater (Lalley, 2002). However, ERG obtained other in formation indicating that wet milling facilities may process this stillage into distillers’ solubl es (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 wa shing (a portion of which may be recycled to the steeping process (Rausch, 2006).

Other process wastewaters of le sser volumes include those from the ethanol fermentation process and possibly from DS production. These wastewat ers, which are also produced by dry milling operations, are discussed in Secti on 3.1.2 and depicted in Figure 3-2.

4.0 W ASTEWATER 

### T REATMENT AND 

### D ISCHARGE 

### O PTIONS



### The wastewater generated at etha nol production facilities is handled in a variety of ways. The following sections describe the wastewater tr eatment systems operated at wet and dry milling facilities.

4.1 Dry Milling Facilities

As described in Section 3.0, dry milling facilities commonly pro cess whole stillage into coproducts through separation and ev aporation processes. These facilities often combine the resulting evaporator condensate with other proc ess wastewaters, such as CIP water, scrubber water, and boiler blowdown and anaerobically treat this wastew ater 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, th e Bio-Methanator. The Bio-Methanator is capable of reducing COD levels in dry milling wastewaters by 90 percent. According to Phoenix Bio-Systems, approximate ly 40 dry milling facilities currently use BioMethanators for their process wastewater (rough ly 44 percent of dry milling facilities based on estimates described in Section 5.0), and this nu mber 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 recycl e 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 ac ids 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 Page 11

11 from process wastewater allows 100 percent recy cle 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 proce ss 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 Ne braska NPDES permit writer and Phoenix BioSystems about the 10 dry milling facilities in Ne braska, the following wastewater systems are operated:

 Three facilities operate Bio-Me thanators (two of which recy cle 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 wa stewater (type of wastew ater treatment is unknown).

Of the dry milling facilities that discharge pr ocess wastewater, three discharge to POTWs and one discharges directly to surface waters. Th e 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 osmosi s reject water directly in accordance with NPDES permits.

4.2 Wet Milling Facilities

As described in Section 3.2, wet milling facilities often treat th eir steepwater condensate in anaerobic systems followed by aerobic polishing systems. Wet milling facilities may treat the stillage (or processed stillage) from the ethano l 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 Ta ble 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 19 October 2006 Page 12

12 Table 4-1. Ethanol Production Facilities in N ebraska

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 CH 4 is flared

ADM Columbus Wet Anaerobic cells (lined and covered) followed by SBR (anaerobic and aerobic stage) Surface (NPDES) CH 4 from anaerobic cells is used in boilers (emergency flare). CH 4 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) CH 4 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 pr ocess 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 Page 13

13 4.3 CH 4 

### Recovery and Use

The information ERG gathered on the et hanol industry indicates that the CH 4 

### generated in anaerobic digesters is commonly collected and eith er flared or used as fuel in the ethanol production process. According to Phoenix Bio-Sy stems, almost all of the facilities operating Bio-Methanators collect the generated CH 4 

### 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 CH 4 

### generated, and these facilities flare the CH 4 

### instead. (Holman, 2006c). Most commercial biomethanation systems contain emergency flare equi pment that is intended to be used if biogas production exceeds requirements. (Merrick, 1998)

NPDES permit writers for ethanol producti on facilities are no t aware of any CH 4 

### generated from anaerobic wastewater treatment at ethanol production facilities that is released to the atmosphere. Anaerobic lagoons are typically covered. The CH 4 

### generated is used as fuel in the ethanol production process if econo mical, and if not, the CH 4 

### is flared. (Holman, 2006a, 2006b, 2006e) One NPDES permit writer indicated that CH 4 

### could potentially be rel eased 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 CH 4 

### generated in the anaerobic portion of these SBRs (Holman, 2006e).

One potential incentive for ethanol production facilities to recover CH 4 

### generated from anaerobic wastewater treatment system s (in addition to using CH 4 

### for fuel) involve s Prevention of Significant Deterioration (PSD) permits. In orde r 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 ha ve incentive to recover CH 4 

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

4.4 Wastewater Characterization

Up to 20 liters of stillage may be generated fo r 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 concentrat ion of COD in this stillage may be as high as 56 g/L based on published inform ation from 1985 (Wilkie, 2000). In ethanol production processes that use cellulosic-based fe edstock, the stillage ma y 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 signi ficantly lower than the stillage due to the removal of solids a nd solubles. The COD concentrat ion 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 conde nsate, boiler blowdown, sc rubber water, and CIP water, typically ranges from 25 to 400 gall ons per minute (gpm) (Merrick, 1998) (PBS, 2006) (Holman, 2006e) (NE report) (Indus trial WaterWorld). COD load ings typically range from 2,000 to 16,000 pounds per day (ppd) (Ruocco, 2006a).

### Memorandum 19 October 2006 Page 14

14 The nutrient (nitrogen and phosphorus) content of ethanol production wa stewaters has been reported to b e relatively low, with the exception of stillage generated from barley feedstock (Wilkie et al, 2000) (Holman, 2006g). Nutrient a ddition may be required for the proper growth of microorganisms in activated sludge system s treating ethanol produc tion wastewaters (U.S. EPA, 1986).

5.0 GHG E MISSIONS 

### E STIMATES



### From the information obtained in this study and described in previous sections, ERG estimated the potential GHG emissions from the ethanol produc tion industry. This section provides the methodology for the emission calculations, along w ith 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 th e ethanol production industry as follows:

Total Industry

CH 4 

### emissions = Dry milling CH 4 

### emissions + Wet milling CH 4 

### emissions

Dry Milling

CH 4 

### emissions = CH 4 

### emissions for facilities w ith Bio-Methanators (BM) + CH 4 

### emissions for facilities with other anaerobic treatment (AT)

CH 4 

### 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) = CH 4 

### yield / COD loading (pub lished data) (Merrick, 1998)

CH 4 

### 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 (#Facil ities - #Facilities * %BM)) EF (Generic AT) = Bo * MCF Bo = 0.25

### Memorandum 19 October 2006 Page 15

15 MCF = 0.8

Wet Milling

CH 4 

### emissions = CH 4 

### emissions for steepwater + CH 4 

### emissions for stillage

CH 4 

### emissions for steepwater = #Facil ities * 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

CH 4 

### 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 assumpti ons for the overall process:

 ERG only included data related to the corn-based process, th e focus of this memorandum, as described in Section 2.0.

 ERG assumes that the only GHG emitted fr om the ethanol production industry is CH 4 

### and the only emissions source is anaerobic wastewater treatment systems. The only information obtained in this study about nitrific ation/denitrification sy stems 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 ar e currently 91 dry milling facilities in operation.

### Memorandum 19 October 2006 Page 16

16  The RFA lists 43 ethanol facilities unde r construction or expanding and based on inf ormation received [ref], ERG expects that these are all dry milling facilities. ERG did not include the construction/expansio n 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 f actor for Bio-Methanator units based on example bio-gas production and CH 4 

### yield data supplied by Phoenix Bio-Systems in a published report (Merrick, 1998).

 ERG assumed a percentage of anaerobic treat ment 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 Tabl e 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 write rs (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 remain ing one-third operate aerobic activated sludge systems. Table 5-2 summar izes 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 Tabl e A-1 for listing of wet milling facilities.



### 5.3 Preliminary Estimates of GHG Emissions

Given all of the assumptions described in Sect ions 5.2 through 5.4, ERG es timates that the total potential GHG emissions from the et hanol industry is 55.2 Gg/year of CH 4 

### or 1.16 Tg-CO 2 

### 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 Estimate a

(CH 4 Gg/year) Realistic Estimate a (Tg-CO 2 equivalent/year) Worst Case Estimate b (CH 4 Gg/year) Worst Case Estimate b (Tg-CO 2 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 CH 4 recovery b – 100% anaerobic treatment, no CH 4 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 CH 4 

### generated from anaerobic treatment systems.

 For the dry and wet milling calculations, ER G used the high end of the COD loading ranges obtained.

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

reasons:

### Memorandum 19 October 2006 Page 18

18  ERG has not obtained su fficient wastewater in formation for the wet milling process such as typical percentage of wastewater recycl e 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 producti on facilities do not treat their process wastewater anaerobically, and thus substantiates the decr ease from the worst case to the realistic case; however, ERG does not know the actua l percentage of anaerobic treatment.

 ERG did not perform a thorough investiga tion of potential GHG emissions from nitrification/denitrification pr ocesses and/or sludge or stor mwater runoff. However, ERG did not obtain any information that indicates potential for GHG emissions from these

sources.

6.0 N EXT 

### S TEPS



### 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 inve ntory, ERG recommends that the calculation method be revised to estimate emissions based on produc tion. Sufficient data exist to calculate dry milling emissions based on production, but additiona l data are needed for wet milling operations, including data to relate the wa stewater COD load to ethanol production. In addition, because the type and amount of co-products produced at we t milling facilities sign ificantly affects the wastewater flows and COD loads, co-production da ta would also need to be obtained. If this data can be obtained and the wet milling wastew ater 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 th e amount of wastewater that is treated anaerobi cally. Data collection activities coul d also address greenhouse gas emissions from sludge handling, storm water runoff, and nitrificiati on/denitrification systems.

These data may be obtained through furthe r 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 tele phone 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 CH 4 

### is recovered at both wet and dry milling ethanol production facilities. ERG believes additional contacts within EPA’s Office of Air would supplement informati on regarding potential incentives to recover emissions (including CH4) and any studies on ai r emissions from ethanol production wastewater treatment operations.

### Memorandum 19 October 2006 Page 19

19 7.0 R EFERENCES



### EIA. 2005. U.S. Department of Energy – En ergy 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 – En ergy 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 Ke lly 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 Produc tion Facilities.” (September 5).

Holman. 2006d. Telephone conversation with Peggi Badten of the City of Aberdeen, South Dakota and Sarah Holman of ERG. “S outh 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 Faci lities – 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. A nn Wilkie of University of Florida, Soil and Water Science Department and Sarah Ho lman of ERG. “W astewater stillage from ethanol production fac ilities.” (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/cont ent/BECTextor.pdf#search=%22wet%20m illi ng%20ddg%22 . Date Accessed: October, 2006.

IDED. 2004. Iowa Department of Economic De velopment. 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 Ag ency. Summary Information on Fuel Ethanol Plants in Illinois. Available online at: http://www.epa.state.il.us/ai r/perm its/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 Nationa l 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. Wastewat er 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 Envir onmental 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/i ndustry/ne_ethanolplants2006.pdf . Date Accessed: October, 2006.

### Memorandum 19 October 2006 Page 21

21 PBS. 2006. Phoenix Bio-Systems (PBS). Gene ral 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%20downl oads/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='Fro m% 20Niche%20to%20Nation%3A%20Eth anol%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-Methanator s (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 Agri culture (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 Suppor t Document for the Ethanolfor-Fuel Industry. EPA 440/1-86/093. (April).

U.S. EPA. 2006. Office of Tr ansportation and Air Quality. Regulatory Announcement: Removal of Reformulated Gasolin e Oxygen Content Requirement. EPA420-F-06- 035. (May).

VeraSun. 2006. VeraSun Energy Corporati on. Facilities. Av ailable online at: http://www.verasun.com/facilities/ . Date Accessed: October, 2006.

Wilkie, et al. 2000. “Stillage Characterizati on and Anaerobic Treatment of Ethanol Stillage from Conventional and Cellulosic Feedstocks.” Biomass and Bioenergy . 19: 63- 102.

### 22 Appendix A

U.S. ETHANOL PRO DUCTION 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 California a Corona CA Cheese whey 5

Pacific Ethanol Madera CA Corn 35

Parallel Products b 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, LLC a Denison IA Corn 40

Archer Daniels Midland c,d Cedar Rapids IA Corn 200

Archer Daniels Midland c,d Clinton IA Corn 200
Big River Resources, LLC a West Burlington IA Corn 40
Cargill, Inc. d Eddyville IA Corn 35
Corn, LP a Goldfield IA Corn 50
Frontier Ethanol, LLC Gowrie IA Corn 60

Global Ethanol/Midwest Grain Processors Lakota IA Corn 95

Golden Grain Energy, LLC a 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, LLC a Hanlontown IA Corn 50
Lincolnway Energy, LLC a Nevada IA Corn 50
Little Sioux Corn Processors, LP a Marcus IA Corn 52

Otter Creek Ethanol, LLC a Ashton IA Corn 55
Permeate Refining Hopkinton IA Sugars & starches 1.5

Pine Lake Corn Processors, LLC a 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 Processors a Galva IA Corn 27
Siouxland Energy & Livestock Coop a Sioux Center IA Corn 25 10

Tall Corn Ethanol, LLC a Coon Rapids IA Corn 49
US BioEnergy Corp. Albert City IA Corn 100
VeraSun Energy Corporation e Ft. Dodge IA Corn 120
VeraSun Energy Corporation e Charles City IA Corn 110
Voyager Ethanol, LLC a Emmetsburg IA Corn 52
Xethanol BioFuels, LLC Blairstown IA Corn 5
Adkins Energy, LLC a Lena IL Corn 40

Archer Daniels Midland c Peoria IL Corn 100

Archer Daniels Midland c,d Decatur IL Corn 290
Aventine Renewable Energy, LLC d Pekin IL Corn 100 57

Illinois River Energy, LLC Rochelle IL Corn 50
Lincolnland Agri-Energy, LLC a 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, LLC a 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, LLC a 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, LLC a Hopkinsville KY Corn 33

Parallel Products b 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. EXOL a Albert Lea MN Corn 40 8

Agri-Energy, LLC a Luverne MN Corn 21

Al-Corn Clean Fuel a Claremont MN Corn 35

Archer Daniels Midland c,d Marshall MN Corn 40
Bushmills Ethanol, Inc. a Atwater MN Corn 40
Central MN Ethanol Coop a Little Falls MN Corn 21.5
Chippewa Valley Ethanol Co. a Benson MN Corn 45
Corn Plus, LLP a Winnebago MN Corn 44
DENCO, LLC a Morris MN Corn 21.5
Ethanol2000, LLP a Bingham Lake MN Corn 32
Granite Falls Energy, LLC Gr anite Falls MN Corn 45

Heartland Corn Products a Winthrop MN Corn 36
Heron Lake BioEnergy, LLC Heron Lake MN Corn 50

Land O' Lakes a,d Melrose MN Cheese whey 2.6
Minnesota Energy a Buffalo Lake MN Corn 18
Northstar Ethanol, LLC Lake Crystal MN Corn 52
Pro-Corn, LLC a Preston MN Corn 42
Golden Triangle Energy, LLC a Craig MO Corn 20
Mid-Missouri Energy, Inc. a Malta Bend MO Corn 45

Missouri Ethanol Laddonia MO Corn 45
Northeast Missouri Grain, LLC a Macon MO Corn 45

Alchem Ltd. LLLP Grafton ND Corn 10.5

Archer Daniels Midland c 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

AGP a Hastings NE Corn 52

Archer Daniels Midland c,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, LLC a Plainview NE Corn 26.5
KAAPA Ethanol, LLC a 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, LLC a Wentworth SD Corn 50
Glacial Lakes Energy, LLC a Watertown SD Corn 50
Great Plains Ethanol, LLC a Chancellor SD Corn 50
Heartland Grain Fuels, LP a Aberdeen SD Corn 9
Heartland Grain Fuels, LP a Huron SD Corn 12 18
James Valley Ethanol, LLC Groton SD Corn 50

Millennium Ethanol Marion SD Corn 100
North Country Ethanol, LLC a 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, LLC a Big Stone City SD Corn 50
Prairie Ethanol, LLC Loomis SD Corn 60
Redfield Energy, LLC Redfield SD Corn 50
Sioux River Ethanol, LLC a Hudson SD Corn 55
VeraSun Energy Corporation e 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, LLC a Monroe WI Corn 48

Central Wisconsin Alcohol Plover WI Seed corn 4
United WI Grain Producers, LLC a Friesland WI Corn 49

Utica Energy, LLC Oshkosh WI Corn 48

Western Wisconsin Renewable Energy, LLC a Boyceville WI Corn 40

Wyoming Ethanol Torrington WY Corn 5

Total Curren t 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, 2 004), (IEPA, 2006), (LBNL, 2003), (MPCA, 2002), (NDEQ, 2006), (NEB, 2006). e – Data obtained at (Verasun, 2006) for VeraSun individual plants.