Minnesota now produces about 550 million gallons of ethanol a year. The transportation fuel

consumes one-sixth of the state’s corn crop, and that could rise to one-quarter by 2010. Today nearly all gasoline sold in Minnesota is blended with ethanol.

A 56-pound bushel of corn produces about 2.7 gallons of ethanol and 17 pounds of distiller’s dried grains with solubles, or DDGS. Minnesota produces more than one million tons a year.

DDGS used to be a low-quality product, without much value. But Minnesota’s “new generation” ethanol plants make high-quality DDGS that are in demand to feed cattle, dairy cows, swine, poultry — even fish. But that’s not all this coproduct is being used for.

A Morris ethanol plant is pressing DDGS into protein lick blocks to supplement forage diets for cattle, horses, elk and dry cows.

Corn solids, called solubles, remain in the ethanol processing water. These solubles can be dried and used to fortify baby pig feed.

DDGS can be broken out into components such as amino acids, proteins and specialty sugars, for use in medicines and foods, including low-cal sweeteners, nutritional drinks and weight loss products.

DDGS can be pressed into fuel pellets and burned in pellet stoves or gasified.

Ethanol processing generates carbon dioxide, which is used to carbonate beverages, make dry ice, and flash freeze meat.

High-grade ethanol is used in beverages, such as Shakers Original American Vodka, made by Chippewa Valley Ethanol Company in Benson. High-grade ethanol is also used in solvents, cleaning products, cosmetics and medicines.

CORN STOVER

It’s known as corn trash — the stalks, leaves, husks and cobs that ordinarily end up back on the field after combining — but don’t call it garbage. One researcher likens corn stover to “a barrel of crude oil.” U.S. farmers produce three tons of stover per acre of corn, and this abundance has sparked many creative efforts to find profitable uses.

Shelled corn has long been used in home heating stoves. Corn stover also makes a good heating fuel. The University of Minnesota Morris plans to gasify corn stover to heat and cool the college campus. Corn stover is also being turned into pellet fuel for home pellet stoves. Someday, corn stover energy could be used to generate hydrogen for fuel cells.

Corn stover’s potassium and phosphorous remain after burning and can be used as fertilizer.

Corn stalks make comfortable cattle feedlot bedding. In compost dairy barns, corn cobs are a

soft substitute for wood-chips.

Rigid, disposable corn-stalk mats for hog nurseries and farrowing crates are a renewable alternative to rubber mats, which have to be disinfected between uses.

Fiber mats for soil erosion-control, mulching and seeding are being made from corn stover and other crop residues.

Corn stover is useful for soaking up liquids in absorbent products such as oil filters and oil-absorbent blankets and mats.

Corn stover and other ag fibers, such as beet pulp, wheat straw and barley straw are replacing wood pulp in paper, oriented strand board, and composite building materials.

Corn stover and many other kinds of ag fibers can be refined for biodegradable polymers, which are used in plastics, packaging films, foams, adhesives and many other manufactured goods. The processing has not yet been commercialized, but scientists like the University of Minnesota’s Roger Ruan say it’s just a matter of time.

Today, Minnesota’s ethanol plants use just the corn kernel to make alcohol, but it’s also possible to make ethanol from crop residues, like corn stover. ■

Easing the sidestream flow
AURI and corn growers sponsor nation’s first study to improve handling of ethanol coproduct

By Dan Lemke
 

Waseca, MN — Ethanol is a triumph for Minnesota agriculture. The state’s annual production — 500 million gallons last year — was only 11 million gallons 15 years ago. And it’s likely to surge again in 2013 when a state provision could require a 20-percent ethanol blend in all gasoline sold here.

But in the wake of ethanol’s free-flowing fuel production, there are sidestreams that need to keep pace with the industry.Distiller’s grain, an ethanol coproduct, is typically coated with another coproduct: syrup. Then it is dried to yield DDGS or distiller’s dried grains with solubles. The Minnesota Corn Growers Association estimates the state already produces 1.4 million tons of DDGS per year, and more plants are being built.
 

Most of these DDGS are sold for poultry, swine and cattle feed, but supply exceeds the state’s demand, so the overflow is often shipped to global markets. However, long distances and moisture can cause the DDGS to become compacted and sticky, making it difficult to unload.
 

Alan Doering of AURI’s coproduct utilization lab in Waseca says some DDGS shipments have been discounted by thousands of dollars because of poor flow and the cost of extra labor and time to unload ships, train cars and trucks.

So AURI and the Minnesota Corn Growers initiated a study to see what conditions hamper DDGS flow and what may be done to improve it.

Many of the corn association members and leaders “are also investors in these ethanol plants” and aware of the flowability problems, says Yvonne Simon, a Minnesota Corn Growers staff person.

About 5,000 producers own shares in Minnesota’s 14 ethanol plants, which use 16 percent of the state’s corn crop, according to the Minnesota Department of Agriculture. Moreover, the industry leverages 5,000-plus jobs and $1.3 billion in economic activity.

“This is an issue that affects every ethanol plant in Minnesota,” Doering says. “It can impact their profitability, which means it affects the bottom line of the producers who have invested in them.”
 

The MCGA and AURI enlisted Jenike & Johanson, a bulk solids design and engineering firm from Massachusetts, to to evaluate various DDGS traits. The firm analyzed distiller’s grains flow characteristics, compared different grain hopper designs and outlet sizes, and tested the effect of pelleting grains.

Five DDGS samples were tested: two controls and three modified samples, including deoiled DDGS, a reduced-syrup sample and pelletized DDGS.

The study, completed in October, revealed that “particle size and relative humidity played the biggest roles in flowability,” Doering says. “We expected that the de-oiled DDGS and the pelleted distiller’s would flow best, but that wasn’t always the case.”

The study showed that larger particles flowed best, regardless of oil or syrup content. The larger particles even flowed better than the pelleted sample, which showed minimal improvement.

Humidity had little impact until it rose above 60 percent — at that point distiller’s grains quickly absorb moisture, which can reduce flowability. Particles also tend to expand as they warm, which can reduce flowability.

The study was the first of its kind in the country and has drawn attention from around the nation. “We don’t have all the answers yet, but what we do know about distiller’s grains now can impact not only ethanol plants but feed managers and even our own product development,” Doering says. “We’ve answered a lot of questions, but created a few more, too.”

“We have some information that is leading edge,” says Simon. “Now that we know how DDGS are affected by things like heat and humidity, we need to figure out how we can keep the distiller’s stable, so once it reaches markets like China, Japan or Spain, it flows and has good nutrition value.” ■
 

The flowability report summary is available here.

Energizing ethanol
Minnesota plants find ways to save energy while making it

Owatonna, MN — It takes energy to make energy. The electricity and fossil fuels needed to convert corn to ethanol can cost millions, depending on a plant’s size.