Increased pressure on local aquifers used to grow and refine corn into ethanol, high levels of nitrogen in groundwater from pesticides and fertilizers, and runoff pollution in streams and rivers are a few of the potential impacts, said the committee that wrote the report.
Chaired by Dr. Jerald Schnoor, a professor of engineering at the University of Iowa, the six member committee examined policy options and identified opportunities for new agricultural techniques and technologies to help minimize effects of biofuel production on water resources.Recent increases in oil prices together with subsidy policies have led to a dramatic expansion in corn ethanol production and high interest in further expansion over the next decade.
Because of strong national interest in greater energy independence, in this year's State of the Union address, President George W. Bush called for the production of 35 billion gallons of ethanol by 2017, which would equal about 15 percent of the U.S. liquid transportation fuels.
The committee found that agricultural shifts to growing corn and expanding biofuel crops into regions with little agriculture, especially dry areas, could change current irrigation practices and greatly increase pressure on water resources in many parts of the United States.
The effects will vary by region. In the Northern and Southern Plains, corn generally uses more water than soybeans and cotton, while the reverse is true in the Pacific and mountain regions of the country.
Water demands for drinking, industry, and such uses as hydropower, fish habitat, and recreation could compete with and constrain the use of water for biofuel crops in some regions.
Growing biofuel crops requiring additional irrigation in areas with limited water supplies is a major concern, the report warns.
'Fundamental knowledge gaps' prevented the committee from making reliable assessments about the water impacts of future large scale production of feedstocks other than corn, such as switchgrass and native grasses.
In addition, other aspects of crop production for biofuel may not be fully anticipated using the frameworks that exist for food crops. The water requirements of food crops may not translate directly into the requirements for biofuel crops.
'For example, biofuel crops could be irrigated with wastewater that is biologically and chemically unsuitable for use with food crops, or genetically modified crops that are more water efficient could be developed,' the committee said.
The quality of groundwater, rivers, and coastal and offshore waters could be impacted by increased fertilizer and pesticide use for biofuels, the report says.
High levels of nitrogen in stream flows are a major cause of low-oxygen or 'hypoxic' regions, commonly known as 'dead zones,' which are lethal for most living creatures and cover broad areas of the Gulf of Mexico, Chesapeake Bay, and other regions.The report notes that there are a number of agricultural practices and technologies that could be employed to reduce nutrient pollution, such as injecting fertilizer below the soil surface, using controlled-release fertilizers that have water-insoluble coatings, and optimizing the amount of fertilizer applied to the land.
The switch from other crops or noncrop plants to corn would likely lead to much higher application rates of highly soluble nitrogen, which could migrate to drinking water wells, rivers, and streams, the committee said.
When not removed from water before consumption, high levels of nitrate and nitrite - products of nitrogen fertilizers - could have significant health impacts, warns the report.
Excessive levels of nitrate in drinking water have caused serious illness and sometimes death. Once taken into the body, nitrates are converted into nitrites. The serious illness in infants is due to the conversion of nitrate to nitrite by the body, which can interfere with the oxygen-carrying capacity of a child's blood, according to the U.S. Environmental Protection Agency. This can be an acute condition in which health deteriorates rapidly over a period of days. Symptoms include shortness of breath and blueness of the skin.
Nutrient and sediment pollution in streams and rivers could also both be attributed to soil erosion. High sedimentation rates carry financial consequences as they increase the cost of often-mandatory dredging for transportation and recreation.
The committee observed that erosion might be minimized if future production of biofuels looks to perennial crops, like switchgrass, poplars or willows, or prairie polyculture, which could hold the soil and nutrients in place better than most row crops.
The committee also identified other ways that farming could be improved, such as conservation tillage and leaving most or all of the cornstalks and cobs in the field after the grain has been harvested.
For biorefineries, the water consumed for the ethanol production process - although modest compared with the water used growing biofuel crops - could substantially affect local water supplies, the committee concluded.
A biorefinery that produces 100 million gallons of ethanol a year would use the equivalent of the water supply for a town of about 5,000 people.
Biorefineries could generate intense challenges for the management of local water supplies, depending on where the facilities are located.The report held out the hope, however, that 'use of water in biorefineries is declining as ethanol producers increasingly incorporate water recycling and develop new methods of converting feedstocks to fuels that increase energy yields while reducing water use.'
Jonathan Kaplan, director of the Sustainable Agriculture Project for the Natural Resources Defense Council, views the report in the context of a major Farm Bill that is now working its way through Congress.
'The National Academy of Sciences report makes it clear that unless Congress acts decisively through the Farm Bill and comprehensive energy bill, increased biofuels production will increase water pollution from agriculture and intensify many regional and local water shortages.'
'The report also details many agricultural practices, technologies, and other biomass crops that could help reduce total water use and pollution while we increase the production of biofuels. But to deliver on the promise of biofuels, Congress must dramatically increase funding for Farm Bill conservation programs and reform them to get more conservation per dollar,' Kaplan said.
It is not enough to increase the volume of production, he said, 'We also need to shift our biofuels policies to improve environmental and energy security performance.'
The study was sponsored by the McKnight Foundation, Energy Foundation, National Science Foundation, U.S. Environmental Protection Agency, and National Research Council Day Fund.