Urbana, Illinois
March 18, 2009
On the
University of Illinois South
Farms, 320 acres are devoted to the largest biofuels research
farm in the U.S., growing crops that could be used to produce
renewable energy. Last year the farm planted miscanthus,
switchgrass, corn, and restored prairie as bioenergy crops. The
goal is to compare insect and disease challenges, environmental
benefits, economic opportunities and potential energy per acre
of each.
Tim Mies, who directs the Energy Farm, said that research at
Illinois has already shown that the giant miscanthus grass can
produce over double the biomass per acre as corn. “It does this
apparently without the need for any nitrogen fertilizer, very
few other inputs and it adds significant amounts of organic
matter to the soil. So, miscanthus might be a third crop for
Illinois, and one particularly suited to marginal land,” Mies
said.
“What having 320 acres devoted to energy crops on the energy
farm allows us to do is to consider the benefits as well as
possible downsides to these new crops and test whether other
native plants might do just as well.
“Miscanthus planting is currently a very labor-intensive
operation,” Mies said. “Because it is a sterile crop and so
doesn’t produce seed, the question is how do you reproduce it at
an agronomic scale?” He said that sterility has the advantage of
preventing the plant from becoming invasive. “But, because
there’s no seed, we have to physically go in and remove the
rhizomes underground, break them apart and then replant them
into the new fields. Rather like harvesting and then planting
potatoes.”
U of I researchers are working to develop machinery that can
efficiently plant and harvest it, rather than digging it up with
a shovel or by hand. For miscanthus to be an effective crop, “we
need to scale up the machinery to accommodate planting thousands
of acres of it. Potato-handling equipment is something we’ve
been looking at because it can physically go into the dirt and
lift out the material,” Mies said. “However, are moving away
from being able to plant half an acre a day toward 20 acres,
with the latest equipment that we are working with.”
Restored prairie as an energy crop is a relatively new concept.
“Illinois used to be a prairie. If we’re going to convert
possibly marginal land back to grasses, restored prairie has the
potential to be a possible biomass source because it is what was
naturally here before modern agriculture,” Mies said.
Crop scientist Steve Long said that ecologists have proposed
this use of the land from theory and very small scale trials.
“Now, for the first time, agronomists and ecologists can work
together to asses the viability of this idea.”
Restored prairie is a mixture of tall grasses and small nitrogen
fixers. Mies said that instead of management through regularly
scheduled prairie burns, it would be harvested as a crop in the
early winter when nutrients have been cycled back to the roots.
“In theory, it makes a lot of sense to convert the land back to
what it used to be, but how that might translate on an agronomic
scale is yet to be seen.”
One of the challenges in growing restored prairie as a biomass
crop is that it can be choked out by other more aggressive
weeds. “There isn’t an herbicide you can use to control the
weeds because something that would kill off the weed would also
kill the plants that you want. There’s no herbicide control you
can use for it,” Mies said.
The consistency of the resulting fuel may also be an issue with
prairie grass. “To process it, you want a consistent material
with very little nutrient left in it,” Mies said. “A field of
switchgrass is all switchgrass, whereas a field of restored
prairie is a mixture of plants and grasses -- the proportions of
which change from acre to acre and bale to bale, a problem you
wouldn’t have with switchgrass or miscanthus.” This
inconsistency could make it very difficult to use the harvested
biomass as a feedstock for processing to ethanol.
Long term, the Energy Farm will conduct research projects on
many more potential biofuel crops. “We want to look at several
more grasses, woody crops, some tree species that might be able
to be used for biofuels, and even some sorghum varieties – not
just one specific crop with a narrow focus. “We want to be a
demonstration and testing farm for any possible biofuels crops
that could be grown in Illinois or in this region.”
Funding for the Energy Farm is provided by the Energy
Biosciences Institute and the University of Illinois. |
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