(This first installment of a three-part series focuses on the potential availability and subsequent conversion of land for energy crop cultivation. Following this segment, EPM investigates new research in genetic modifications geared to provide a revolution in the feedstock portfolio for ethanol, and the challenges that stand in that way.)

When asked for his opinion on the most complete definition of "dedicated energy crops," David Bransby, professor of agronomy and soil at Auburn University in Auburn, Ala., says he doesn't like the phrase to begin with. He prefers "biomass crops" to refer to those species that have little or no value as agricultural commodities, but are good candidates for cellulosic ethanol feedstocks.

"Originally we talked about them as energy crops, but of course, that is a confusing term because … what's corn?" Bransby says. "It's used mainly for feed, but it can be used to produce energy." It's a slippery issue to deal with from a definition point of view. "If you wanted to refer to them as energy crops, that's fine, but the best way perhaps is to say biomass energy crops—just to distinguish from grain," Bransby says. "They are crops grown primarily for the purpose of producing energy."

According to Daniel Kammen, professor at the University of California at Berkeley, dedicated energy crops are simply those cultivated with the primary purpose of producing fuel—not food. An energy crop, however, doesn't necessarily exclude food crops. "I'm actually hopeful that we will see a wave of crops that serve both needs," Kammen says. "We can envision faster-growing tree species and things like that. It's a very broad definition and, to my mind, this is not a horizon that we have explored very much. Figuring out which [crops] are and which one's aren't … I'm not sure we know yet."

Unknown Territory
While potential and acreage both exist for dedicated energy crops to be a legitimate force in ethanol production, the research is relatively sparse considering the number of studied species. However, cellulosic ethanol is undergoing major technological developments, and because the cultivation of cellulosic feedstocks is not as far advanced as corn agriculture, it suggests that there is room for improvement and innovations. Dedicated energy crops would be feedstocks for cellulosic ethanol, for which the technologies are not as economical as starch-based ethanol production.

One obstacle is that gasification technology requires the feedstock to be dried down to about 20 percent moisture. With current dryers, that is a difficult feat, Bransby says. So, the ways energy crops are dried, cured, stored and shipped are still being considered. One model that could be patterned by energy crop cultivation is the one provided by the cotton industry, says Daniel de la Torre Ugarte, a professor at the University of Tennessee who has written one of the most comprehensive studies to date on biomass crops. "The cotton is collected in the field and then taken to a cotton gin where the fiber is separated from the seed," Ugarte explains. "Then, it is baled and shipped out to textile mills. This process has similarities to how energy crops would be harvested and shipped. Also, any farmers who have grown wheat or hay would have the experience and equipment to handle several energy crops."

Bransby has studied several varieties that have potential as dedicated energy crops—some of which are not indigenous species—with exciting numbers in terms of yields. "The problem is that non-native species get strong resistance from environmental groups, and these guys are so powerful that they can stop you in your tracks," Bransby says. The introduction of non-native grasses to the soil could have unknown consequences, says Marie Walsh, researcher for Oakridge National Laboratory's biomass feedstock development program.

The most interest in non-native grasses has been on miscanthus, but data remains scarce. "I'm a little bit hesitant at this time to say that miscanthus is a crop that we could grow throughout the U.S., Walsh tells EPM. "There just hasn't been enough work. Research on miscanthus in the U.S is pretty much limited to only about three or four years worth of data."

Some grasses could generate very high yields per acre but need to be introduced vegetatively, which is far more tedious and expensive than seeding. Miscanthus also requires moderate winters and an even distribution of rainfall, characteristics limiting the regions where it could flourish. "[These] take a little time to integrate," Bransby says. "Expansion of acreage is much more difficult, and until it's been done, certain technological changes and advances need to occur."

Switchgrass is the leading candidate for mass cultivation as a dedicated energy crop, Bransby says. It can be introduced with seeds and will not draw protest from environmental advocates. The yields per acre are greatest in the third year of its establishment, but if left unmanaged, it can be more difficult to collect and harvest. The problem is that the yields are greater over more time, and the switchgrass has often become unruly. "You have to do partial cuts every year," Ugarte says.

Perennial Pricing
Because switchgrass and other dedicated energy crops are not harvested annually, there are some economic challenges in terms of price forecasting and contracts. Ugarte says there will have to be 10- to 15-year institutional arrangements in some cases to stabilize the market for energy crops. This will be the biggest change for farmers and the most difficult sell in terms of initiating conversion of land use.

It seems like the best opportunity for biomass crops lies in the Farm Service Agency's Conservation Reserve Program (CRP). It encourages farmers to convert highly erodible cropland or other environmentally sensitive acreage to vegetative cover, such as tame or native grasses, wildlife plantings, trees, filter strips or riparian buffers. The Farm Service Agency says CRP "reduces soil erosion, protects the lakes, improves water quality, establishes wildlife habitat, enhances the ability to produce food and fiber, and reduces sedimentation in streams and wetland resources."

Participants enroll in CRP contracts for 10 to 15 years. "The payments on that range from about $30 to $50 an acre to about $150 [per acre], depending on where you are," Bransby says. "Most of them are perennials, so technically you wouldn't be farming." A perennial is a plant that produces flowers and seeds more than once and therefore lives for more than one year—like switchgrass, one of the approved crops among a wide variety of grasses and shrubs. The legislation that is in place allows the CRP land to be harvested once every three years. Again, this could be a problem, Walsh says, because the materials would be woodier and harder to harvest.

Based on the future of the markets for bioenergy and bio-based products, significant amounts of land could shift to the production of perennials. Studies have shown that if the price was high enough for energy crops to attract the interest of farmers, perennial grass crops producing an average of 4.2 dry tons per acre would be competitive with the current crops on about 42 million acres of cropland and land in the CRP.

"Down here in Alabama, we have probably millions of acres that are idle in our black belt region," Bransby says. The Southeast is an area of the United States that could lead in the production of biomass crops, where switchgrass and other species wouldn't have to compete with corn and soybeans for acreage. The possibility does spread the ability to evolve the ethanol industry outside the Midwest. The northern plains and the Southeast will be the major areas that could support proliferation of energy crops, where yields will be much greater per acre for perennial grasses and the competition will be thin. The benefit of growing dedicated energy crops will be limited to certain niche areas. "California grows a lot of boutique crops, so we are not going to grow acre upon acre of dedicated biofuels crops," Kammen says.

The USDA and the U.S. DOE have reported that the United States can produce nearly 1 billion tons of biomass annually from agricultural land while continuing to meet food, feed and export demands. This projection includes 428 million dry tons of annual crop residues, 377 million dry tons of perennial crops, 87 million dry tons of grains used for biofuels and 106 million tons of animal manures.

Dedicated energy crops would be mostly native grasses and fast-growing trees in the Southeast and on the northern plains. Perennial crops (trees or grasses) grown primarily for bioenergy expand to 35 million acres at five dry tons per acre per year. Ninety-three percent of the perennial crops are assumed to be available for bioenergy and the remainder of other products.
While there will be some areas where energy crops won't be able to compete with commodity crops for farmland, Ugarte maintains that focusing on the growth and utilization of biomass could be an advantageous alternative to concentrating on increasing corn use for ethanol because a wider geographic area would benefit from ethanol production. There is a variety of crops being studied for their potential as energy crops; because of environmental concerns, economic factors and logistics, Bransby says the best choices are switchgrass and other prairie grasses indigenous to North American soil.

Nicholas Zeman is an Ethanol Producer Magazine staff writer. Reach him at nzeman@bbibiofuels.com or (701) 746-8385.