Fuel from the Fields

Fuel from the Fields

Agricultural production has traditionally focused on food and fiber, but a third F has entered the picture. Everyone’s talking about homegrown fuel.

Whether processing soy diesel or harvesting French-fryer fat, Americans are searching for affordable, sustainable sources of energy available within our own borders. Some say we should look to new petroleum sources in the Gulf of Mexico or to new ways of refining coal, but an increasing number of analysts are saying the grass is greener in the pasture.

Grain or Grass?

Since the gas crisis of the early 1970s, researchers across the nation, including some at the University of Tennessee Institute of Agriculture, have been exploring the potential of biofuels to offset our dependence on foreign oil. The standing debate has been whether to focus on the use of grain (primarily corn and soybeans) to produce fuels or whether other crops might be the answer.

The Energy Policy Act of 2005 establishes standards to ensure that gasoline marketed in the United States contains specified minimums of renewable fuel, for example, ethanol. Most scientists agree, however, that using grains for biofuels is not the answer. “The volume of production is just not there,” says Dennis West, an agronomist with the Department of Plant Sciences of the University of Tennessee’s College of Agricultural Sciences and Natural Resources. At current production levels, if all of the U.S.-grown soybeans were converted to soy diesel, only 6 percent of current diesel usage would be displaced, he says.

Another problem is competing use. “Diverting a food crop to energy use will drive up prices paid to farmers, but it will also create competition between the food and energy markets,” West says. “Not to mention that the yearly inputs needed by grain crops, like seed, make them comparatively expensive crops to grow.”

West has devoted his career to traditional breeding techniques to increase the amount of grain that can be produced per acre. His new project is developing a corn variety that would be better suited for production as an energy crop. One promising candidate is a hybrid of teosinte, a perennial relative of corn that grows wild even on Mexico’s most marginally productive land. Teosinte sprouts new shoots annually from rhizomes in the ground. “We would cut it for the biomass, not the grain,” West says. “In the spring new plants would sprout and farmers would be spared the expense of replanting fields.”

After two seasons of production, the jury is still out about the biomass potential of teosinte, but West did produce a promising candidate this year–a 14-foot plant that perhaps he’ll nickname Goliath. A field of plants like that would produce quite a bit of fodder.

Biomass. . .Green Gold. . .Tennessee Tea

While biomass utilization and conversion were discussed long before recent high fuel prices, President George Bush turned the nation’s attention toward biomass production in 2006 when he mentioned the possibilities posed by switch grass in his state-of-the-union address. The president set goals to make cellulosic ethanol competitive to produce by 2012 and to use it to replace 75 percent of Middle Eastern oil imports by 2025. Intensive research and technological development—something akin to the 1960s effort to reach the moon–will be required to meet the lofty goal.

Corn is currently cheaper to convert to ethanol than biomass crops; however, switch grass and other biomass crops have the potential to outpace grain-based biofuels in sheer volume of production. As an added benefit, most potential biomass crops can be produced on marginal lands, have the potential for value-added industrial uses beyond fuel production, and are not critical links in the human food chain.

Don Tyler, a soil scientist and crop production specialist, and his partners in the UT Bio-Based Energy Analysis Group have been studying switch grass for the U.S. Department of Energy for years. Tyler is working on production mechanics for the native grass-turned-crop–from planting and management to harvesting–while Burton English, Daniel de la Torre Ugarte, and other agricultural economists look at issues related to marketing switch grass and such other biomass crops as woody perennials and corn.

Their work indicates that the South, particularly the state of Tennessee, could play a huge role in meeting future renewable energy goals. English and Ugarte say Tennessee has an opportunity to lead the nation in the production of dedicated energy crops.

But unlocking the potential of biomass means solving the complicated problems of transportation and processing. Biotechnology, says Neal Stewart, will play a key role. Stewart, a professor in the Department of Plant Sciences, holds the Racheff Chair of Excellence in Plant Molecular Genetics. He says genetic improvements to reduce the volume of products to be transported will increase interest in biomass production and use.

Stewart and others are using the groundbreaking work of UT’s Bob Conger, professor emeritus of plant sciences who worked with switch-grass biotechnology. “The genomics revolution will enable improvements in switch grass now, whereas it was too immature a science in the 1990s,” says Stewart. His lab is working to engineer switch grass to produce enzymes that will jump-start the digestion process once the grass is cut.

“Complex carbohydrate digestion is central to ethanol production,” Stewart says. “You have to take the plant matter and break it down to its component parts to get the fermentable sugars that produce ethanol and other byproducts. If we can genetically engineer a grass that will help solve part of the processing problem when it’s harvested–and reduce the volume of material to be transported–we’re two steps closer to industrial feasibility.” Other genetic improvements might include increased cellulose content in the plants.

Zong-Ming “Max” Cheng is another UT scientist tackling the biomass problem. His target “crop” is poplar trees. Poplars have been grown as short-rotation trees by the forest industry for producing high-quality paper. Now DOE has also identified them as one of the leading bioenergy crops.

Cheng is working on genetically engineering poplar trees. The idea is to develop supertrees that grow fast, are drought tolerant, use nitrogen efficiently, and have an altered crown architecture for more efficient photosynthesis. Cheng says poplars can be grown as short-rotation fiber and fuel crops (with 6- to 10-year harvest cycles) on marginal land in Tennessee. “Sustainable production of economical feedstocks can increase farmers’ income and alleviate the cost for bioenergy production,” he says.

Among the many problems all the scientists face is the difficulty in finding appropriate research space. Plots with sufficient buffering to allow production of the genetically modified plants can be difficult to come by. The UT Agricultural Experiment Station follows rigorous protocols to prevent cross-breeding between natural plant populations and genetically modified cultivars.

Agriculture’s New Focus

Biofuel production is just one facet of the energy equation, Tim Rials says. “The Holy Grail is not just fuel. It’s a bio-based economy.” Rials is a polymer chemist who specializes in the use of forest products. He also serves as director of a regional center dedicated to biomass research. The UT Agricultural Experiment Station manages one of five such centers for the federal Sun Grant Initiative, which involves a network of U.S. land-grant universities and DOE laboratories. They are partnering to make a bio-based economy a reality for the U.S. As the Southeastern Regional Sun Grant Center, UT serves as a clearinghouse for federal biomass research funds.

Besides the biomass production and transportation research, UT sponsors research into technologies for converting the biomass feedstock into fuels and new bio-based materials. In spring 2007 the center expects to open a small-scale bio-refinery capable of testing new conversion and processing technologies for a variety of potential feedstocks.

Collaborations in the Sun Grant Initiative involve UT’s Chemistry and Civil Engineering departments, as well as the Joint Institute for Biological Sciences and the Institute for a Secure and Sustainable Environment. The Oak Ridge National Laboratory and National Renewable Energy Laboratory in Golden, Colorado, are among the federal partners. Regional collaborators from other research institutions are to be determined by successful grant applications.

Rials says that research to promote bio-based alternative energy will facilitate a new base for our economy and be good for our environment. “Technologies that produce energy and environmentally friendly byproducts for use by industry from renewable, sustainable agricultural commodities will improve the nation’s energy security,” he says. “Just as important, they will promote agricultural and environmental sustainability and enable economic diversification in rural communities.”

Stewart echoes Rials’s thoughts and shifts the paradigm a step further by predicting a new wave of industrial revolution similar to that of the 19th century: “The advances we make as we research bioenergy production may one day be known as the renaissance of agriculture and biotechnology,” Stewart says.

In 1862 President Abraham Lincoln signed the Morrill Act of 1862 establishing the nation’s system of land-grant universities. The result has been a thriving agricultural industry and affordable food and fiber for the nation. As America invests in research to produce a sustainable green economy, who knows what the true power of biomass might become?