CHAMPAIGN, Ill. — Giant Miscanthus (Miscanthus x giganteus),a hybrid grass that can grow 13 feet high, may be a valuable renewablefuel source for the future, researchers at the University of Illinoisat Urbana-Champaign say.
Stephen P. Long, a professor of cropsciences and of plant biology, recently took that message to Dublin,Ireland, where the British Association for the Advancement of Sciencesponsored the annual BA Festival of Science Sept. 3-10.
Closer tohome, two of Long’s doctoral students, Emily A. Heaton and Frank G.Dohleman, delivered their Miscanthus findings at the 49th annualAgronomy Day, held on campus Aug. 18 and attended by more than 1,100visitors from across the Midwest.
“Forty percent of U.S. energyis used as electricity,” Heaton said. “The easiest way to getelectricity is using a solid fuel such as coal.”
Dry, leaflessMiscanthus stems can be used as a solid fuel. The cool-weather-friendlyperennial grass, sometimes referred to as elephant grass or E-grass,grows from an underground stem-like organ called a rhizome. Miscanthus,a crop native to Asia and a relative of sugarcane, drops its slenderleaves in the winter, leaving behind tall bamboo-like stems that can beharvested in early spring and burned for fuel.
Rhizomatousgrasses such as Miscanthus are very clean fuels, said Dohleman, who isstudying for a doctorate in plant biology. Nutrients such as nitrogenare transferred to the rhizome to be saved until the next growingseason, he said.
Burning Miscanthus produces only as much carbondioxide as it removes from the air as it grows, said Heaton, who isseeking a doctorate in crop sciences. That balance means there is nonet effect on atmospheric carbon dioxide levels, which is not the casewith fossil fuels, she said.
Miscanthus also is a very efficientfuel, because the energy ratio of input to output is less than 0.2,Heaton said. In contrast, the ratios exceed 0.8 for ethanol andbiodiesel from canola, which are other plant-derived energy sources.
Besidesbeing a clean, efficient and renewable fuel source, Miscanthus also isremarkably easy to grow. Upon reaching maturity, Miscanthus has fewneeds as it outgrows weeds, requires little water and minimalfertilizer and thrives in untilled fields, Heaton said. In untilledfields, various wildlife species make their homes in the plant’s leafycanopy and in the surrounding undisturbed soil.
Illinoisresearchers have found that Miscanthus grown in the state has greatercrop yields than in Europe, where it has been used commercially foryears, Long said. Full-grown plants produce 10-30 tons per acre dryweight each year. Miscanthus yields in lowland areas around the Alps,where the climate is similar to the Midwest, are at least 25 tons peracre dry weight, wrote Heaton and colleagues in a paper published in2004 in the journal Mitigation and Adaptation Strategies for GlobalChange.
Last year, Illinois researchers obtained 60 tons per hectare (2.47 acre), Long said at the BA Festival of Science.
Usinga computer simulator, Heaton predicted that if just 10 percent ofIllinois land mass was devoted to Miscanthus, it could provide 50percent of Illinois electricity needs. Using Miscanthus for energywould not necessarily reduce energy costs in the short term, Heatonsaid, but there would be significant savings in carbon dioxideproduction.
The Illinois Miscanthus crop began three years agowhen Heaton planted 400 Miscanthus rhizomes, which were generated fromthree rhizomes donated by the Turfgrass Program in the department ofnatural resources and environmental sciences. Because Miscanthus issterile, cuttings of Miscanthus rhizomes must be used to create newplants.
Now in their third year, the three 33-by-33 feetMiscanthus plots at the intersection of South First Street and AirportRoad in Savoy, Ill., are considered mature. Their 10-foot tall stemsare twice as high as switchgrass, a prairie grass native to Illinois.Grown side by side, Miscanthus produces more than twice as much biomassas switchgrass, Heaton said.
To investigate how Miscanthus is soproductive, Dohleman and others take measurements of photosynthesisthroughout the day. He measures the intensity of the sun and thenplaces a leaf in a chamber, allowing him to measure the rate ofphotosynthesis depending upon ambient sunlight. Preliminary resultsshow that Miscanthus has a 27 percent greater rate of photosynthesis atmidday compared with switchgrass.
Nine different fields acrossthe state are being used to help estimate Miscanthus productivity,Heaton said. Plots in Champaign and Christian counties each have morethan 2 acres of Miscanthus, and DeKalb, Pike, Pope, Wayne, Fayette andMason counties have smaller plots. Plots in Champaign County have shownthe greatest yearly yields, according to Long’s 2004 progress report tothe Illinois Council on Food and Agricultural Research, which fundedthe experiments.
“It is my hope that Illinois will take the lead in renewable energy and that the state will benefit from that lead,” Long said.
Othervarieties of Miscanthus have been grown successfully in Indiana,Michigan and Ohio. However, the giant Miscanthus being grown by theIllinois researchers has the greatest potential as a fuel sourcebecause of its high yields and because it is sterile and cannot becomea weed, Heaton said. “Miscanthus sacchariflorus and some of the otherfertile Miscanthus species can be quite invasive,” she said.
At aresearch station near Hornum, Denmark, giant Miscanthus has been grownfor 22 years in Europe’s longest-running experimental field. The crophas never been invasive and rhizome spread has been no more than 1.5meters (4.92 feet), said Uffe Jorgensen, senior scientist for theDanish Institute of Agricultural Sciences.
The next step, Longsaid, is to demonstrate how Miscanthus goes from a plant to a powersource. Existing U.S. power plants could be modified to use Miscanthusfor fuel as in Europe, he said.
Long collaborates withresearchers at the Institute of Genomic Biology to study whetherMiscanthus could be converted to alcohol, which could be used as fuel.
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