Heat, power – and cellulosic ethanol – all are potential uses of giant miscanthus, say researchers.
University of Illinois graduate student Matt Maughan shows to what heights miscanthus can grow.
Giant miscanthus, a prolific perennial grass soon to be utilized for heat and power, may also be an ideal raw material for cellulosic ethanol production, say industry experts.
In 2011, USDA approved four Biomass Crop Assistance Program (BCAP) project areas to help growers in Missouri, Arkansas and Ohio establish about 18,000 acres of the potential biofuel crop. They’ll plant it this spring, then for two years BCAP will supplement the cost of harvesting and transporting its biomass to processors.
Establishing the crop is the hard part. Growers propagate rhizomes of the sterile grass and then wait two to three years for a good field to reach production level. When fully mature, it can produce 8-12 tons of dry matter per acre for 15 years.
Local agribusinesses requiring heat are very interested in buying pelletized giant miscanthus to avoid higher and higher propane costs, says Jon Griswold. He is the CEO of Aloterra Energy LLC, which in partnership with MFA Oil, applied for the BCAP projects.
“We can process giant miscanthus into pellets that burn with a similar Btu value as wood, and at a much cheaper cost than burning propane or crude oil,” he says.
But burning miscanthus is its lowest-value use, says Griswold.
“Within two to three years, there will be a push for cellulosic ethanol rather than corn-based ethanol,” he predicts. “In terms of ethanol, this grass produces three times the yield of corn per acre.”
Giant miscanthus has a future as a cellulosic biofuel, agrees Tom Voigt, an Extension agronomist at the University of Illinois. “We are continuing our research on it and finishing up a U.S. Department of Energy study at five sites in the eastern U.S. I have seen nothing to discourage this use of miscanthus.”
Turning miscanthus into heat and power is a much shorter step than converting it to cellulosic ethanol, says Voigt. Yet besides being a perennial that produces high yields, it requires few inputs, holds carbon in soil and controls erosion.
“As giant miscanthus expands into different growing areas, and more data is acquired, we can do a better job of predicting where to grow it,” says Voigt. “It should be grown no farther west than eastern Kansas and eastern Nebraska.”
He estimates that the crop needs at least 25-30” of annual rainfall.
“It will produce on sandy soils if rainfall is spread out. But even on good soils, if there is a long dry period, the yields are not as good,” he says.
The south-central Midwest might be the optimal place to grow giant miscanthus, he adds. But in a year without good growing conditions, yields can drop to about 7 tons/acre, even in an optimal area.
In more northern areas, growers may have trouble establishing the crop, as it isn’t very cold tolerant the first winter after planting. And while giant miscanthus yielded well in eastern Nebraska, it happened in a year when the weather there was more typical of Kentucky.
Also, Voigt predicts that breeders will improve miscanthus – even develop varieties that produce seed. That would make the grass easier to establish, add genetic variation and reduce the potential for severe disease or insect infestations. Genetic improvements could also provide specific varieties suited for heat or cellulosic ethanol, he says.