Evolving ethanol plant becomes more efficient

By John Weiss

The ethanol industry is still evolving, finding new ways to make more energy or co-products with less energy or water and now getting into using more than just the corn kernel.

Larry Ward, vice president of project development for POET Biorefining in Sioux Falls, S.D., said the industry has cut water usage in half in the past 10 to 15 years and is getting even better. POET helped develop the ethanol plant in Preston that was once called Pro-Corn but is now POET; it is also an investor.

While the process used is getting much better, it’s still similar to one used for hundreds of years to make moonshine, he said. You grind up corn and get the sugar out and make that into alcohol. Ethanol plants have to add 5 percent gasoline at the plant so it can’t be used for things besides fuel.


The Preston plant has been expanded significantly from making about 12 million to 15 million gallons a year to about 40 million gallons now. Energy and water use per gallon has been cut in half; water use was once 7 to 8 gallons per gallon of ethanol while it’s now closer to 3 to 3.5 gallons, Ward said.

The plant uses about as much water per year as an average 18-hole golf course, he said.

Despite the gains, Ward believes there are still more efficiencies to be found.

Corn was the first feedstock used because it was easy to handle and readily available, he said. But plants such as the one in Preston use only the inside of the kernel. POET is working with the U.S. Department of Energy on a $200 million plant near Emmetsburg, Iowa, that uses the hull of the kernel as well as the cob. It has 4,000 acres of corn that will be used for the energy.

Besides using more parts of the corn, it will also minimize use of fossil fuels such as natural gas and need even less water, Ward said.

The process is being designed so it can be retrofitted to 22 existing POET plants, possibly including the one in Preston.

That is a first step toward cellulosic ethanol that can use all kinds of cellulose, including trees and grass, he said.

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