Ethanol and Water Quality:
Avoiding Unintended Consequences
Tom Simpson
Dept of Environmental Science and Technology
University of Maryland
Phone: 301-405-5696
E-mail: tsimpson@umd.edu
USDA Global Biofuels Conference
August 20, 2007
Minneapolis, MN
Major Water Issues with
Expanded Ethanol Production
Water Quality
z Managing facility wastewater
z Nutrient impacts from expanded and intensified grain (corn)
production
z Co-location of animal operations near ethanol facilities
z Impact of distillers grains in feed on manure nutrient content
z Potential water quality benefits from some cellulosic feedstocks
Water Quantity
z Facilities consume substantial amounts
z Impact will vary by region
z Will high grain prices increase irrigation in drought prone areas
(Southeast, Mid Atlantic)
Water Use and
Ethanol Production Facilities
Consumptive water use
z About 3.5 to 6 liters of water is consumed for
each liter of ethanol produced *
z Consumption largely comes from evaporation
during cooling
z Plants are achieving greater efficiency over time
z About 3 liters of water per liter of ethanol is
probably low end with current technology
z Producing 72B l/yr (20B GPY) of ethanol, would
consume 216B l/yr (60B GPY) of water
*Institute for Agriculture and Trade Policy
Water use by ethanol plants--potential challenges
Eutrophication: Nitrogen and
Phosphorus over enrichment in
coastal waters
Results in excessive algal growth
z Cause low oxygen
z Reduce clarity and loss of underwater grasses
z Change composition of bottom of food chain
Limiting nutrient for algal growth
z Phosphorus in freshwater
z Nitrogen in salt water (>10ppt salinity)
In estuaries, limiting nutrient changes
with location and season
Monitoring Program Shows Continued Low
D. O. in Mainstem and Large Tributaries
August, 1997 Cruise
Examples of Nutrient
Impacted Coastal Waters
Chesapeake Bay
Northern Gulf of Mexico (MRB)
Tar/Pamlico/Neuse Basins
Long Island Sound
Tampa Bay
Baltic Sea
Sea of Japan
Black Sea/Danube
A 100-Million