Water Useby Ethanol Plants
Potential Challenges

Institute for Agriculture and Trade Policy

The Institute for Agriculture and Trade Policy
promotes resilient family farms, rural communities and ecosystems
around the world through research and education, science andtechnology, and advocacy.
2105 First Avenue South
Minneapolis, Minnesota 55404 USA
Tel.: (612) 870-0453
Fax: (612) 870-4846
iatp@iatp.org
iatp.org© 2006. All rights reserved.

About this publication
Water Use by Ethanol Plants: Potential Challenges
Written by Dennis Keeney, Ph.D., Senior Fellow andMark Muller, Director, Environment and Agriculture Program
Published October 2006

Introduction
Ethanol production using corn grain has exploded in the Upper Midwest. This new demand for corn, and the new opportunities
for value-added processing and cattle production in rural communities, has created the best economic development
opportunity in the Corn Belt states in a generation or more. Ethanol demand has increased rapidly recently because of favorable
economics of ethanol vs. gasoline, and the need for a performance enhancer to replace MTBE (methyl tertiary-butyl ether)in gasoline. Ethanol’s growth has been so dramatic that there are now concerns about the amount of corn available to meetvarious demands, including food, animal feed and export.
Overall, with increased research and investment in the industry and the potential for energy-eﬃcient cellulosic material todisplace corn as the primary feedstock, the environmental footprint of ethanol is expected to markedly diminish.1 However, oneof the most important emerging concerns is the consumptive use of water. Consumptive use of water is broadly deﬁned as any
use of water that reduces the supply from which it is withdrawn or diverted.
As would be expected, most ethanol plants are being sited in the Corn Belt. Many of these regions are also experiencing signiﬁcantwater supply concerns, particularly in the western portion of the region. Minimal data is available on groundwater depletion, andthe scope of future water availability is not clear. It will be to the beneﬁt of the ethanol industry, and rural development initiatives
in general, to get more clarity on the relationship between ethanol production, water consumption, and impacts on water supplies.
Otherwise, shortage of water could be the Achilles heel of corn-based and perhaps cellulose-based ethanol.

Water Use in the Midwest
Conﬂicts over water use are growing in the Midwest.
Large livestock conﬁnements, meat and grain processing plants, and expanding urban regions are all increasing water use. For several years the U.S. Drought
Monitor2 has shown signiﬁcant areas of water stressduring the growing season in parts of the Midwest andGreat Plains although it appears rainfall is returning tonormal levels. However, drought is a recurring issue inthe Midwest and Great Plains.
Rural industries, especially livestock production, consume considerable water. Individual swine, for example, use about ﬁve gallons of water per day. A typical
10-conﬁnement unit with about 1,100 hogs per unit,
would require about 50,000 gallons of water per day(gpd), more during hot dry weather. Beef and dairy
cattle will require 20 or more gpd per head during
summer.3 Increasingly beef ﬁnishing feedlots are being
sited near ethanol plants in order to use the distillers
grains as feed. Distillers grains are a byproduct of ethanol production.
Crop irrigation, while not widespread in the rain fed
Corn Belt east of the Missouri River, is necessary inGreat Plains states. However, crop irrigation is critical to the seed industry, which must have dependable
water to produce high quality seed. Many expanding
cities have already bought water rights from irrigation

Water Use by Ethanol Plants

districts, essentially putting irrigated agriculture out ofbusiness.4
The effects of ethanol production on groundwater
withdrawals will vary locally and be affected by a number of factors including volume used, properties of theaquifer, other uses, and rate of aquifer recharge. Nearsurface water table aquifers (commonly termed unconﬁned) are found along streams and rivers in muchof the Midwest. These aquifers are usually sands andgravels, and recharge readily from precipitation andadjacent water bodies when water is plentiful, but they
are also very susceptible to drought and overuse.5 On
the other end of the spectrum are the conﬁned aquifers that underlay most of the earth’s surface at varying
depths. When they are pumped, the water table is notlowered, rather the water pressure is lowered and thewater in nearby wells declines. They usually recharge
more slowly and while they are a buffer to drought,excessive pumping will cause long term lowering ofwell levels.
Generally, water availability in the Midwest is a local,
rather than a regional issue and will vary over time.
The distribution of groundwater availability andsustainability is not uniform, nor is the distribution ofdemand.6 While western states have developed complicated legal arrangements for issuing water rights
and developing water diversions, these practices havenot been necessary, nor are they likely to be politi3

454322005

2004

2003

2002

2001

2000

1999

01998

1It appears that with the current technology, about 4.0
gal/gal of ethanol is a good estimate, and that overtime ethanol plants are becoming more efﬁcient intheir water recycling technologies.
Figure 2. Ethanol’s estimatednational water consumption
30

25

20

15

102008

2005

2004

2003

2002

2001

0

2000

51999

There are no publicly available records on water use byethanol plants for the U.S. In a review of ethanol states,
only the Minnesota Department of Natural Resources
apparently has records on water use by speciﬁc plants
in reference to the amount of ethanol produced. Minnesota ethanol plants report a wide range of water use,with most plants in a range from 3.5 to 6.0 gallons
of water consumed per gallon of ethanol produced.
Average water use has declined from 5.8:1 in 1998 to4.2:1 in 2005, indicating that the plants are achieving
greater efﬁciency over time.8 The Renewable Fuels Association (http://www.ethanolrfa.org) estimates 3 gal
water per gal ethanol.

61998

Consumptive water use by ethanol plants largely comesfrom evaporation during cooling and wastewater discharge. Ethanol plants are designed to recycle water
within the plant. The quality of the cooling water is
key because of the need for high quality water in theboiler system. As a rule of thumb, water utilization is
10 gallons per minute for each 1 million gallons ofyearly ethanol production. Thus a typical 50 million
gallons per year ethanol plant would need 500 gallons
per minute of water. Modern ethanol plants have sophisticated water treatment techniques to enable recycling of water to boilers. These treatment techniquesshould also enable the plants to use lower quality watersuch as sewage treatment plant efﬂuents and possibly
even water recycled from animal feedlots.

7

Gallons of water per gallon of ethanol produced

Consumptive Water Use

Figure 1. Average water use eﬃciency for Minnesota
ethanol plants

Billions of gallons of water

cally feasible, in the Midwest. This places a greater
impetus on local government to protect local watersupplies from undue exploitation. But regional water
confrontations are certain to increase. South Dakota
and North Dakota recently challenged the Corps ofEngineers’ handling of Missouri River ﬂows, and urban water consumption is depleting aquifers in theChicago-Milwaukee region.7

Institute for Agriculture and Trade Policy

Figure 2 takes Minnesota’s water consumption averages and applies them to national ethanol production
estimates, which includes ethanol plants expected tocome online through 2008. The result is a 254 percent increase in volume of water used in ethanol production from 1998 through 2008. If changes aren’t
made, it is likely ethanol water use will see even moreof an increase in the next decade. Much of the Corn
Belt has plentiful water supplies, and ethanol’s water
demands can be met through appropriate planning.
Other regions, such as the greater Chicago area andwestern Iowa and Nebraska, may run into competing
water uses. One can expect that water availability will
challenge the ethanol industry in many regions, particularly west of the Missouri River.
The state of Iowa prepared a water plan in 1996.9 The
total water use for industrial purposes was estimated tobe about 108 billion gallons per year (bgy), and the report projected water use by 2015 of 120 bgy. Currently Iowa has 2,094 million gallons per year of ethanol
capacity (in operation and under construction). Using the multiplier of 4 gallons water/gallon of ethanol
gives 8,376 million gallons per year, or about 7 percent of the projected water use. There is the likelihoodof a doubling of Iowa’s ethanol capacity by 2012, thus
the potential industrial use could be up to 14 percentof the projected use. This does not necessarily indicatethat state-wide water available for ethanol is in short
supply, but it does show that ethanol plants will add
signiﬁcantly to Iowa’s industrial water use.
While other states do not have similar data available,
regulatory ofﬁcials have expressed concern about therapid growth in ethanol plants and resulting water
consumption. Lack of water has already curtailed someethanol plant permits. One of the ﬁrst was a proposed
plant in Pipestone, Minnesota, by Cargill, Inc. The
Lincoln-Pipestone Rural Water System could not meetthe 350 million gallons per year of water needed by theproposed 100 million gallon per year ethanol plant.10
In Grand Island, Nebraska, a proposed Cargill ethanol
plant was approved after the water needed was offset
by reducing water use in an agricultural area about 15
miles away. In Iowa, Department of Natural Resourcesofﬁcials have cautioned that continued growth of “wetindustries,” which includes ethanol production, in thestate could bring water availability issues.
Water Use by Ethanol Plants

Recommendations
The emerging bioeconomy provides a tremendous
economic development opportunity for the rural Midwest. But Midwest agriculture is built on the region’s
incredible soil and water resources. Economic development is only sustainable if it strengthens, rather
than depletes, these resources. Options for reducing
ethanol’s water consumption include the following.
 Maintain and strengthen regulatory oversight by stateand local government on the siting of ethanol plants,
with special emphasis on the water supply and availability. The ethanol industry can become much

more water efﬁcient, but is unlikely to do so unless
it is required. The permitting process should allow
all potential users of the affected aquifer or surface
water supply to evaluate the impact the facility will
have on water availability now and in the future. As
communities plan for their urban and industrial future, it is important that the permitting process betransparent and allow for local input.
 Where feasible, site plants adjacent to municipal
wastewater facilities. Ethanol is an industrial process that does not require potable water. Most
modern plants have facilities to treat water to thelevel that it can be used within the plants. Municipal wastewater, which would otherwise be discharged to surface waters, can readily be used byan ethanol facility. This approach could also lower
the ethanol plant’s energy costs by reducing water pumping. Wastewater treatment plants havean incentive to encourage secondary uses of theirwastewater because of the increasingly stringent
regulations placed on their discharges to surface
waters.11 Drawbacks to this concept include theresistance to siting industrial facilities close to cities, and the reduction of discharge to streams thatneed wastewater to maintain minimum ﬂows.
 Look for water recycling opportunities with livestock
facilities. The distillers grains from ethanol plants
have considerable value as an animal feed, particularly for cattle. Livestock facilities are increasingly
sited next to ethanol plants so that the distillers
grains can be fed directly to cattle, which is much
more energy efﬁcient than drying and transporting
the grains. Similar to municipal wastewater treat-5

ment plants, adjacent cattle facilities provide an
opportunity for greater recycling of water between
the ethanol plant and the livestock facility.
 Place a greater economic value on water. The ethanol industry made tremendous progress in improving the energy efﬁciency of ethanol production over the past two decades, largely because
corn farmers and ethanol producers could save a
lot of money through more efﬁcient production
practices. Because water is not valued like energy,
that same incentive does not exist for water efﬁciency. Policymakers can use regulation, taxes andeconomic incentives to create a business climatethat promotes greater water efﬁciency in the ethanol industry.
 Maintain publicly available records on ethanol’s water consumption. The extent of the problem ofethanol’s water consumption is largely unknown
because data is not publicly available. Effective policies that promote a more water-efﬁcient ethanolindustry cannot be crafted without more knowledge about the performance of current ethanol
plants. Regardless of whether the plant uses municipal or private water supplies, water consumption should be made publicly available.

References
1.

Dias De Oliveira,M. E. , B.E. Vaughn, and E. J. Rykiel, jr. “Ethanol
as fuel: Energy, carbon dioxide balances, and ecological footprint.”
BioSciences 55:593-601. 2005
2. U.S. Draught Monitor - http://www.drought.unl.edu/dm/monitor.
html.
3. Lardy, Greg and Charles Stoltenow, Livestock and Water. North
Dakota Extension. 1999. http://www.ext.nodak.edu/extpubs/ansci/livestoc/as954w.htm
4. Reisner, M. Cadillac Desert, The American West and Its Disappearing
Water. NATURAL HISTORY. 1993.
5. Libra, R. and M. K. Anderson. 2006. Groundwater and Ethanol.
Report prepared by Robert D. Libra, State Geologist, Iowa Geological
Survey, and Michael K. Anderson, Senior Engineer, Water Allocation
Program, Iowa Department of Natural Resources. August 21, 2006.
6. Libra and Anderson, 2006.
7. Egan, Dan. On a slow quest for water. Milwaukee Journal Sentinel.
February
17,2005.
http://www.jsonline.com/story/index.
aspx?id=302393
8. Personal communication with Sean Hunt, Minnesota DNR, July &August, 2006
9. Ofﬁce of Social and Economic Technical Analysis (SETA). Iowa State
Water Plan. Chapter 5. Projected Water Demand. 1996. http://www.
seta.iastate.edu/publicservices/water/plan/
10. Gordon, Greg. “Water supply can’t meet thirst for new industry.” Star
Tribune, Dec. 27, 2005.
11. Manning, Deborah. Minnesota Ethanol Facilities and Wastewater
Reuse. July 20, 2006. http://www.pca.state.mn.us/publications/presentations/ethanol-0706-manning.pdf

Find more on the bioeconomy at agobservatory.org

6Institute for Agriculture and Trade Policy

Summary Data
Average water use eﬃciency for Minnesota ethanol plants
Ethanol producers

1998

1999

2000

2001

2002

2003

2004

2005

Albert Lea (Exol/Agra Resources)

6.3

6.3

6.0

6.1

5.6

5.5

5.2

4.9

Benson (Chippewa Valley Ethanol)

3.3

3.5

4.8

3.5

3.5

3.1

3.2

3.6

Bingham Lake (Ethanol2000)

4.0

4.2

4.7

4.6

4.3

4.7

4.2

4.4

Buﬀalo Lake (MN Energy)

10.6

6.2

7.1

6.9

7.0

5.8

4.6

4.5

Claremont (Al-Corn)

4.6

4.3

4.1

4.2

3.9

5.4

4.5

4.3

Little Falls (Central MN Ethanol)

—

5.9

4.8

4.2

4.1

3.8

3.5

4.2

Luverne (AgriEnergy LLC)

4.9

5.8

5.2

4.8

4.7

4.6

4.5

4.5

Marshall (ADM)

7.7

7.6

Morris (DENCO LLC)

9.3

10.0

12.3

8.2

6.0

6.1

6.0

6.1

Preston (Pro-Corn)

5.6

5.2

4.7

4.6

4.4

4.1

3.8

4.0
—

St. Paul (MN Brewing)

—

—

18.7

7.9

21.9

32.6

12.2

Winnebago (Corn Plus)

4.1

3.5

3.5

3.5

4.5

4.1

3.9

Winthrop (Heartland)

4.8

5.1

4.3

5.0

4.1

3.7

4.5

4.2

Bushmill’s Ethanol (Atwater)
Granite Falls Energy LLC (Granite Falls)
Northstar (Lake Crystal)
Source: Minnesota DNR Waters, 2006

Water Use by Ethanol Plants

7