All will use a lot of water. It would take about 300 million gallons of water for processing the product and cooling equipment to make 100 million gallons of ethanol each year, according to the Renewable Fuels Association.
While water scientists in Illinois and Iowa say that they are concerned about the impact of that much demand, they are not sending out alarms yet.
``On a statewide scale, it's not a huge amount of water," said Allen H. Wehrmann, director of the Center for Groundwater Science at the Illinois State Water Survey.
The demand for water by the two-dozen operating ethanol plants in Iowa has not damaged water sources or supplies, said Monte Shaw, executive director of the Iowa Renewable Fuels Association. Improving technology means that new plants use as much as 80 percent less water than plants built just five years ago, and most plants recycle their water, so it has more than one use, Shaw said.
Still, the draw on Midwest water supplies is a concern. ``It's an issue that is certainly at the forefront of our minds," said Paul VanDorpe, a scientist at the Iowa Geological Survey in Iowa City.
Many industries use more than a million gallons of water each day, still far less than the 23 million gallons per day used by Champaign and Urbana or the 500 million gallons per day that Chicago pumps from Lake Michigan.
The Mahomet Aquifer, along which several ethanol plants are proposed, has plenty of water. Running across the midsection of the state from the Indiana line to the Illinois River, it supplies an estimated 250 million gallons of water per day.
That is a pittance, given the estimated 13 trillion gallons of water in the aquifer, Wehrmann said. It would take more than a century to pump the aquifer dry, even if no water returned through rainfall and other natural recycling, which amounts to about 40 million gallons per day, he said.
