Division of Agricultural Sciences and Natural Resources / Oklahoma State University


Growing potential . . .

Biofuels: home grown on the range

By Fred Causley

Dwarfed in switchgrass are, from left, Charles Taliaferro, plant breeder, Department of Plant and Soil Sciences; Ray Huhnke, extension specialist with the Department of Biosystems and Agricultural Engineering; Robert Westerman, head, Plant and Soil Sciences; Sam E. Curl, Dean and Director, Division of Agricultural Sciences and Natural Resources; Billy Barfield, head, Biosystems and Agricultural Engineering; and D.C. Coston, Associate Director, Oklahoma Agricultural Experiment Station.

The first step

Oklahoma has thousands of acres of land poorly suited for producing cultivated crops, much of it currently in the Conservation Reserve Program (CRP). Yet there is a crop that such land can and does produce almost naturally—switchgrass. And it goes beyond Oklahoma: there are some 35 million acres in CRP across the United States.

What is the market potential for switchgrass? Not much in itself, but turn that product into ethanol, sell it as an alternative fuel, and the potential is enormous. A major boost in the economy from a proven environmentally friendly product would be a win-win situation.

Realizing that, Oklahoma State University scientists have spent several years breeding switchgrass that can produce greater yields. Charles Taliaferro, plant breeder and a Regents Professor in OSU’s Department of Plant and Soil Sciences, began the research five years ago with a grant from the Lockheed-Martin Corporation. Based on the progress shown, he recently received additional funds to continue the work.

The supply of petrofuels is finite. Burning them produces emissions that include sulfur dioxide, carbon monoxide, and others. The United States currently imports more than half of its oil, contributing to the trade deficit. In addition, the 1992 Clean Air Act mandates the use of reformulated fuels such as ethanol in high-pollution regions, primarily large cities.

"The problem is, most ethanol now in use is made from corn, and the energy output/input ratio is only about 21 percent," Taliaferro says. "The energy output/input ratio for switchgrass is estimated at 4.4, representing a net energy gain of 334 percent."

Taliaferro says the ratio is better with switchgrass because it doesn’t require the nurturing of row crops and it is perennial, eliminating the need for annual planting.

"Our research is part of a larger effort to develop switchgrass as a model herbaceous crop for feedstock in the production of biofuels," Taliaferro explains. "It is part of the U.S. Department of Energy’s National Biofuels Feedstock Development Program administered by Lockheed-Martin at the Oak Ridge National Laboratory located at Oak Ridge, Tennessee.

"Our objectives are to develop varieties with improved yield potential and more adaptation features. We are developing a switchgrass germplasm collection for future use in plant breeding and other scientific investigations. Switchgrass was chosen as a model herbaceous species because of its wide adaptation and high biomass potential."

Taliaferro says switchgrass is found in the central and eastern portion of the United States from the Gulf Coast to Canada. Switchgrass grows on many different soil types, from bottomland to less productive upland soils. The wide distribution of the species is a plus, because strains can be found growing under a variety of environmental conditions, meaning it can be widely planted and cultivated. Additionally, switchgrass has high biomass production with minimal inputs relative to other perennial grass species.

The researcher says his Oklahoma Agricultural Experiment Station switchgrass breeding project has resulted in yield increases of up to 20 percent in biomass production over base populations. In addition, the work to date has assembled a large collection of switchgrass germplasm to provide a basis for long-term improvement through selective breeding.

Though switchgrass was selected as the model herbaceous species for development as an energy crop, Taliaferro notes that it is but one of many potential biomass feedstocks available. The principal existing sources of biomass for energy in the state would be from mixed native grassland, tame pastures, and crop residues such as wheat straw.

Modan Das, a post-doctoral research assistant, and Rose Edwards,
senior research specialist in the Department of Plant and Soil Sciences,
take growth measurements in switchgrass plots. OAES plant breeding
efforts have increased switchgrass yields up to 20 percent among the
experimental breeding materials currently under evaluation.

From biomass to biofuel

The technology to ferment grain starch to ethanol is an ancient technology known at all levels of society, from scientists to moonshiners. The process was augmented in recent years by using enzymes to break plant composition down to basic sugars and submitting them to fermentation. However, the procedure remains both expensive and complicated for mass-scale use.

"There are three plant components to consider with grasses," says Billy Barfield, professor and head of OSU’s Department of Biosystems and Agricultural Engineering. "Cellulose is made up of long chains of six-carbon sugars. Hemi-cellulose is made up of long chains of five-carbon sugars, and lignin holds them all together.

"To bring them to the conversion state, you first have to break the plant components apart, then mechanically or chemically separate them. Enzymes break them down further to glucose and pentose molecules. You have to ferment the mass to produce alcohol, then distill the alcohol off to concentrate it."

Barfield says work on improving the process of converting biomass to liquid fuel is proceeding at a number of places around the world. Researchers in his department and in OSU’s School of Chemical Engineering are evaluating the economics of converting biomass to liquid fuel.

Another way switchgrass and other biomass could be converted to fuel is through gasification. A more versatile process than fermentation, gasification is a process whereby carbonaceous feedstocks are converted into synthesis gas, primarily hydrogen and carbon monoxide, by burning.

Industry currently uses municipal waste, old tires, coal, petroleum coke, and fuel oil to create synthesis gas, or syngas. Switchgrass and other "lignocellulosic materials," such as tree branches, animal wastes, etc., can be used as well. One way to make use of such material is to co-fire it with coal in an electric generation furnace.

Syngas can also be used to produce products in industry, such as ammonia, urea, acetic acid, and many other industrial chemicals.

Mining biomass

"Growing switchgrass or other species as feedstock for energy production would have to be operated more like a mining operation than farming," says Francis Epplin, professor of Agricultural Economics at OSU. "Before anyone would invest $100 million into an Oklahoma biofuel facility, they would have to be sure of a steady supply of biomass. This would mean producers dealing with long-term contracts."

Epplin explains that if a farmer plans to plant corn and isn’t comfortable with his knowledge of what the price will be, he can hedge the crop and determine how much it will bring in 18 months.

That sort of infrastructure is not in place for grasses. Epplin’s job, along with OSU agricultural engineer Ray Huhnke, is to determine the circumstances under which it would be feasible to produce a profitable crop and to determine the most appropriate place to locate a biofuel facility.

An economically efficient biofuel-from-biomass system would require coordination of production and transportation with processing. The processing firm could engage in long-term contracts with growers. Alternatively, Epplin says the processor could vertically integrate by acquiring control of a sufficient quantity of land through long-term leases to fulfill plant requirements.

Another option would be for feedstock producers to form a processing cooperative. In either case, vertical coordination of biomass production would be required to achieve efficient use of the conversion facility.

"To really know the economies of size, that is, what size of plant would be needed to be profitable, and therefore how much biomass would be required to keep it going, we will have to have a large laboratory scale or a pilot plant. With adequate funding, we hope to see a pilot plant in the not-so-distant future," Barfield says.

"Our overall objectives are to determine how to best use Oklahoma’s resources: land, labor, and capital. We have to learn if, and under what circumstances, our state could produce biofuel without subsidies."


Agriculture at OSU Fall / Winter 1997
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