From corn to your tank -- making ethanol

Tractor trailers filled with bright, yellow corn roll off of Highway 65 into the Mid-Missouri Energy plant constantly, at all hours, five days a week.

So begins the first basic step of making ethanol.

During a recent plant tour, plant manager Billy Gwaltney explained the process:

The trucks are stopped at a gated entry to an area behind the plant. A section of the top of the trucks is removed and an automated metallic probe jabs into the corn, where a sample is sucked through tubes into a lab just inside the plant.

Inside, lab assistants quickly run tests for moisture, weight and vitality. The trucks make their way into a receiving pit. Usually, a truck will bring a load of about 900 bushels, which is about six acres' worth of corn.

Corn is then dumped onto an underground conveyor belt, where it is moved to one of two 100-foot-tall corn silos. Once there, the corn is ground into flour with hammer mills.

Then the flour goes through a "cook step," which converts the flour and starch into sugar in a slurry tank. In the third and final step, the sugar is converted into ethanol in one of three 750,000-gallon fermentation tanks.

It takes 50 hours to ferment, culminating in what is basically 200-proof alcohol. Two-thirds of what is produced is a corn mash that is converted into what is called dried distillers grain with solubles, or DDGS. That is used as an animal feed.

One-third of the product, once it is filtered, is pure ethanol.

A relatively small amount of unleaded gasoline is added so that the product is denaturalized, which Gwaltney explains makes it undrinkable. The only reason that is done, he said, was so the company can avoid paying a $27 per gallon beverage tax.

Ethanol, which sells at about $2.30 a gallon, makes up 80 to 85 percent of the plant's revenue. The ethanol is then shipped out by truck, a nearby railroad or by river to gasoline companies.

-- Scott Moyers