In December, the U.S. ethanol industry was reported to be producing up to 7.3 billion gallons of ethanol annually. Figuring that it takes one bushel of corn to make 2.8 gallons of ethanol, the ethanol industry used about 2.5 billion bushels of corn.

What's more, the industry is expected to have the capacity to produce an additional 6 billion gallons by the end of 2008, potentially bringing total ethanol production to more than 13 billion gallons (using more than 4.5 billion bushels of corn) by the end of 2008.

At the end of last year, President George W. Bush signed into law the Energy Independence and Security Act of 2007, which expands the Renewable Fuels Standard (RFS), beginning with 9 billion gallons of biofuels in 2008. This will ramp up to 36 billion gallons of biofuels by 2022.

“The growth in ethanol production together with the violent spike in world oil prices [rising to $100 a barrel in January 2008] stress the importance of the investment that Congress made in our domestic ethanol industry in the energy bill,” said Bob Dinneen, president of the Renewable Fuels Association, recently. “By putting the focus on developing ethanol production from resources in addition to corn, we now have a road map in place to begin mitigating the impacts of volatile oil markets ….”

America's scientists, in fact, have already begun to follow this road map. They are researching cellulosic ethanol produced from corncobs and cornstalks, as well as switchgrass, poplar trees and more.

Government-funded studies

The U.S. Department of Energy (DOE) is investing up to $375 million to speed up basic research in the development of cellulosic ethanol and other biofuels at three DOE research centers.

The DOE BioEnergy Science Center, headed by the DOE's Oak Ridge National Laboratory, will study the plant cell walls of corn, switchgrass and poplar, and how those cell walls can more easily be broken down by enzymes in the ethanol production process.

The DOE Great Lakes BioEnergy Research Center will concentrate on breeding plants in which carbon is directed into easily degraded cell wells, with a focus on switchgrass and miscanthus. The research center is led by the University of Wisconsin-Madison in close collaboration with Michigan State University.

The DOE Joint BioEnergy Institute will be led by DOE's Lawrence Berkeley National Laboratory. Among its efforts will be improving plants for ethanol feedstock and studying the molecular mechanisms behind the breakdown of lignocellulose into fermentable sugars.

Although the first biorefineries using cellulosic biomass resources are not expected to be in operation until sometime in the next decade, farmers may want to learn about species such as switchgrass and miscanthus, as well as the processes that convert biomass to ethanol, says Ken Vogel, scientist with USDA's Agricultural Research Service (ARS), Lincoln, NE. Vogel points out that USDA and several land grant universities are conducting research in addition to what is being done at the DOE research centers.

Private-sector research

POET (www.poetenergy.com), an ethanol producer based in Sioux Falls, SD, is working with several agricultural equipment manufacturers to improve methods for harvesting, storing and transporting corncobs in large quantities.

POET plans to transform its 50-million-gallon-per-year grain-to-ethanol plant in Emmetsburg, IA, into an integrated corn-to-ethanol and cellulose-to-ethanol plant. It reports it has chosen corncobs for several reasons. The collection of cobs will require minimal additional effort and will have little to no impact on the environment. The cob represents just 18% of the above-ground stover, so collection will not harm soil quality. The cob's carbohydrate content is higher than the rest of the corn plant, which will allow it to produce more ethanol. Finally, because the cob has a higher bulk density than other parts of the cornstalk, it will be easier to transport from the field to the ethanol plant.

Ceres (www.ceres.net) in Thousand Oaks, CA, has been using marker-assisted breeding and other technology platforms to increase biomass yield and to make other agronomic and compositional improvements in crops such as switchgrass and sorghum.

In October last year, Ceres announced it has entered into an agreement with Texas A&M University's Agricultural Experiment Station to research and commercialize high-biomass sorghum. The project will focus on producing biomass from sorghum's stems, stalks and leaves, more so than the grain.

Switchgrass research

Ceres also is sponsoring research at South Dakota State University (SDSU) to develop improved switchgrass for the northern Great Plains. The multiyear program will focus on developing higher-yielding cultivars adapted to production in northern latitudes, often called upland types.

Switchgrass is tolerant of a wide range of environmental conditions, and compared with many other perennial grasses and conventional crop plants, it produces relatively large amounts of biomass under both good and poor growing conditions, says SDSU plant breeder Arvid Boe.

Switchgrass (Panicum virgatum) gained widespread attention as a cellulosic feedstock when President Bush mentioned it in his 2006 State of the Union address. Native to the prairies of North America, this perennial grass is widely adapted. In fact, Ceres indicates that it could be planted as an energy crop throughout the United States. The rapidly growing grass is established from seed.

Iowa State University has published a brochure that addresses several agronomic aspects of switchgrass, including establishment, fertility needs and yield. It can be viewed at www.extension.iastate.edu/store/ItemDetail.aspx?ProductID=12610.

Switchgrass cultivars (non-transgenic) grown in Nebraska farmers' fields are yielding an average 3 to 5 tons of biomass/acre, with the potential to produce 240 to 400 gal. of ethanol/acre. However, ARS's Vogel has planted some research plots to improved cultivars in Nebraska that have produced 6 to 7 tons of biomass/acre, which would translate to 480 to 560 gal. of ethanol/acre. Conversion technology produces about 80 gal. of ethanol/ton of biomass, Vogel explains.

The ARS at Lincoln, NE, is developing switchgrass for use on marginal cropland similar to land that would be eligible for the Conservation Reserve Program, Vogel says.

He also has been working on some experimental switchgrass hybrids that may be capable of yielding 10 tons/acre to produce approximately 800 gal. of ethanol/acre. However, it may take about 10 years before these can be commercialized.

ARS scientists also are evaluating seed rates, herbicide and fertilizer applications, and frequency of cutting studies to help develop guidelines that farmers can use in the future. Vogel expects that these guidelines will eventually be made available through state extension services.

Giant miscanthus

Another species that has gained a lot of attention as a potential ethanol feedstock is Giant Miscanthus (Miscanthus x giganteus), a sterile hybrid between M. sacchariflorus and M. sinensis Anderss. The tall perennial grass is established via rhizomes. Like switchgrass, it also is widely adapted, but mostly from Nebraska east to the Atlantic Seaboard.

Iowa State University also has published a brochure that addresses several agronomic aspects of miscanthus hybrids. You can find it at www.extension.iastate.edu/store/ItemDetail.aspx?ProductID=126101.

The University of Illinois has studied M. giganteus as an energy crop since 2002. In 2004, the university received a $1 million grant from the Illinois Council on Food and Agricultural Research. With this five-year grant, Stephen Long, crop science professor, the University of Illinois, and his colleagues have concentrated on the propagation, physiology and input requirements of the grass.

Long and Frank Dohleman, graduate research assistant in plant biology, report that in side-by-side tests at three Illinois locations, Giant Miscanthus produced more than double the biomass of switchgrass per acre (14.1 tons/acre), which could produce more than 1,400 gal. of ethanol/acre. (See the chart on page 42 that compares biomass and ethanol production yields of several feedstocks.)

The university also has been studying how Giant Miscanthus, as an ethanol feedstock, would impact local crop production and the rural economy.

In addition, the energy company British Petroleum (BP) announced last year that it is funding a $500 million research program in which the University of Illinois will collaborate with the University of California at Berkeley and the Lawrence Berkeley National Laboratory in research at the Energy Biosciences Institute (EBI). Thomas Voigt, University of Illinois Extension specialist, says that, as part of the EBI research, the University of Illinois will establish a 340-acre energy farm where Giant Miscanthus will be studied and produced as a cellulosic ethanol feedstock for biofuel production. Researchers also will study the possible use of corn crop residues, switchgrass and other herbaceous perennials as fuel sources.

SOURCES OF BIOMASS FOR ETHANOL PRODUCTION
HARVESTABLE BIOMASS (TONS/ACRE) ETHANOL PRODUCTION (GALS./ACRE)2 MILLION ACRES NEEDED FOR 35 BILLION GALS. OF ETHANOL % OF 2006 HARVESTED CROPLAND NEEDED FOR 35 BILLION GALS.1
Corn grain1 4.6 456 77 24.7
Corn stover2 3.0 300 117 37.6
Corn total 7.6 756 46 14.9
Switchgrass 5.6 563 62 20.1
Miscanthus 14.1 1,410 25 8.0
Sources: 1USDA-NASS, 2U.S. Department of Energy