Argonne: Ethanol plants decrease water, energy use

By Timothy Charles Holmseth | June 02, 2008
Water and energy consumption by ethanol plants was the focus of a survey conducted by the Renewable Fuels Association in 2007. Afterward, the RFA asked Argonne National Laboratory to perform a statistical analysis of the survey data. The results recently came in, and they confirm that ethanol plants are using less water and energy than before.

The RFA's survey asked 22 operating dry and wet mills—representing 1.81 billion gallons of annual production—what their energy and water usage was in 2006. Those answers were compared with similar data collected by the USDA in 2001.

Argonne's analysis found that:
› Ethanol yields increased 6.4 percent in dry mills and 2.4 percent in wet mills.

› Total energy use (fossil fuels and electricity) decreased 21.8 percent in dry mills and 7.2 percent in wet mills. Dry mills decreased electricity use by 15.7 percent alone.

› Water use decreased 26.6 percent in dry mills.

According to the Argonne analysis, ethanol production totaled 1.77 billion gallons in 2001. By 2006, that amount had increased to 4.9 billion gallons, representing a growth of 276 percent.

Despite the decrease in water and energy usage, some in the industry believe it should be even lower. Keith Kor, general manager of Corn Plus LLLP in Winnebago, Minn., said he believes the amount of water and energy each plant will be allowed to use will be allotted by the government someday. "I think within the next three years, whether it be state or federal, governments are going to step in and say, ‘Ethanol plants, this is how much water you can use. Get there,'" he said. "We're trying to get it down to where it takes one gallon of water to make one gallon of ethanol."

To do so, Kor said his plant has been developing technology that is designed to capture most of the water that is being used during the process. "I'm looking at some technology right now that I'm hoping will be able to capture all the water," he said. "Our plant has looked at capturing as much water as possible." The technology being tested at Corn Plus has had positive results, which Kor said will be publicly released in the near future.

Because of the need for water to make slurry, hydrolyze the starch and execute the distillation process, water is always going to be needed, Kor acknowledged. "I know some plants say they have a zero discharge, but that's not true," he said, explaining that some water is always lost going out the stack.

Kor said he believes water is going to be a valuable commodity in the future. "We need to run our plants efficiently," he said. "I think we want to be good stewards of the land and do whatever we can to reduce [usage]."