USA: ARS researcher discovered way to improve barley feasibility in ethanol production

Great strides have been made in research to find the most economical and beneficial way to process barley into ethanol.

U.S. Department of Agriculture's Agriculture Research Service scientist Kevin Hicks has discovered a way to reduce the problem-causing viscosity of barley in ethanol production, The Prairie Star posted July 05.

“There are some technical problems in using barley in ethanol production,” explained Hicks of Wyndmoor, Pennsylvania. “First, there is the abrasive hull, which is hard on equipment. Second, there is the lower starch content, which results in the need for larger plants to handle larger amounts of grain in order to get the same amount as a corn-processed ethanol plant. Then, there is the beta glucans, which can lower cholesterol, but are a viscous material, so that when you mash the barley, the viscosity is so high you cannot stir it.”

Hicks has been researching the use of barley in ethanol production for several years. Last year, at the annual Ethanol Producers and Consumers (EPAC) conference, Hicks reported he and his research team had found using hulless barley helps reduce the wear and tear on process equipment.

This year at the EPAC conference held in mid-June at Whitefish, Montana, Hicks discussed updates on barley research in ethanol production, focusing on making ethanol production using barley has a feasible feedstock.

“Hulless barley varieties have higher starch content and are beginning to look more like corn,” he said. “And they don't have those abrasive hulls.”

There is equipment available to hull the barley prior to processing. Hicks said they are also working to further develop the technology available to make it withstand the abrasiveness of the hulls. However, the drawback to processing hulled barleys is deciding what to do with the hulls. Hicks said there has been research on using the hulls for biomass energy production, in which gasification would be used to combust and burn the hulls for converting into bio-oils and processing for running the ethanol plant.

Using the hulls for cellulosic ethanol production has also been researched. Hicks said if 100 pounds or about two bushels of hulled barley were used, the barley would have to go through a roller mill and aspirator to remove the hulls before producing about 32.4 gallons of ethanol.

The hulls would then be pretreated, washed and using a new enzyme, converted into 3.5 gallons of ethanol for a total of 35.5 gallons of ethanol out of the 100 pounds of barley. Using cellulosic ethanol production, barley hulls could produce an additional four to six million gallons of ethanol per year, said Hicks.

Barley hulls could also be used as a feedstock for fluidized bed combustors for steam production or gasification for hydrogen production. If used in a pyrolysis unit as a bio-oil, barley hulls could replace 40 percent of an ethanol plant's natural gas usage if the plant installs a combustion unit for the barley hulls, said Hicks. With $6 natural gas, Hicks said it is easy to understand why using barley hulls for energy become economical.

“We use computer simulation models to estimate feasibility and if our research makes sense or not,” he explained. “We make these computer simulation models available for research and education. I wouldn't recommend using them for producing a plant; instead, use our models the thinking of building your plant.”

Researcher Jerry Berglan of Sidney, Mont., has been studying the production of hulled and hulless barley varieties for growth in the northern Great Plains. “Fifteen to 35 percent of the malt barley grown is rejected for malt every year,” he said. “This gives us a golden opportunity to use it as a feedstock for ethanol.”

One hulless variety Berglan is researching has a double-haploid and is resistant to lodging. Thus far, this variety has yielded 140 to 150 bushels per acre under irrigated conditions, which enhances its value for malt and ethanol production, he said. “I hope someone will step forward and do a plant to handle wheat, durum and barley rather than corn,” said Berglan. “There is a potential there.”

After making great strides in developing hulless barleys for ethanol production, Hicks has begun to concentrate on breaking down the beta glucans in barley, another problem in ethanol production.

“Beta glucans are like a starch and cellulose or somewhere in between,” he explained. “We use enzymes to break them down into small bits without as much viscosity or if we could use enzymes to totally break them down, we could increase our yields of ethanol with the additional glucose produced.”

Barley is made up of 65 percent starch and 5 percent beta glucans. If the beta glucans were broken down using enzymes, Hicks said barley could produce 70 percent starch and “look more like corn,” in ethanol production.

However, Hicks said he has been disappointed in the enzyme research, whereas the different groups tested did not breakdown the glucans 100 percent. “We found a bunch of enzymes to do it, and a lot of those are developed commercially, but they didn't do the job completely,” he said. “That's when we realized there was something missing.”

The missing enzyme was beta glucosidase, an enzyme that breaks down the last molecule in the beta glucan. After adding beta glucosidase, the barley was completely broken down, including the beta glucan. Hicks said barley-produced ethanol could be more profitable by using the right combination of enzymes.

“We used some feed grade enzymes and some more expensive ones,” he explained. “We found you can save money by using the right enzyme mixture.”

Finding the right combination of enzymes can be simplified by using a computerized enzyme calculator developed by Novozymes, the biotech-based world leader in enzyme and microorganism production. The computerized calculator allows individual plants to determine which combination of enzymes would best fit their production strategy, according to account manager Catherine Belaski of Denver, Colo.

“You can change plants from wheat to barley without too much difficulty if you change the enzyme cocktail along with it,” she said. “In areas where they grow wheat or barley, such as Montana, you can adjust for the difference in the availability fairly easy.”

The calculator can help determine enzyme mixtures for blended feedstocks as well as changing feedstocks. It tells plant managers what enzymes to use in what proportions and how to adjust for different blends of feedstocks, explained Belaski.

Producing ethanol using small grains can increase the plant's production cost, but it balances out in the end, said Belaski, because the enzymes help increase the ethanol yields. “Enzyme cost is about 10 percent of the total cost of producing ethanol using small grains,” she said. “It will balance out. The enzyme cost becomes a drop in the bucket compared to what you're extracting using them.”

With small grains, the enzymes are commercially produced and shipped to the individual plants rather than made on the spot for the plants. Cellulosic enzymes are made on site.

While beta glucosidase is not currently available commercially, Belaski said selling the beta glucan to pharmaceuticals is an option for those producing ethanol, using barley as a feedstock, while using enzymes to break down the barley and wheat to produce more ethanol. “Enzyme blends become cost-effective when you expand ethanol production beyond the Corn Belt,” she said, noting corn has virtually no insoluble and soluble fibers to make it viscous in ethanol production. “Enzymes increase the plants' production capacity, reduce the overall operational costs and give you flexibility in feedstock selection.”

However, ethanol producers need to consider heat and making minor design changes when using enzymes for feedstock breakdown. “Enzymes are more heat sensitive,” she said. “They are not for jet cookers. They need lower temperatures, which could result in some minor plant design changes.”

Overall, using enzymes in ethanol production could reduce problems caused by viscosity and increase the feasibility of using barley and wheat as ethanol feedstocks, said Belaksi. “Viscosity causes problems in the back end of the process, but it could be treated up front with an enzyme cocktail.”

07 July, 2006