U of I news
'Let's just harvest invasive species.' Problem solved?
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[November 25, 2013]
URBANA — Although invasive Asian carp have been
successfully harvested and served on a dinner plate, harvesting
invasive plants to convert into ethanol isn't as easy. According to
a recent study at the University of Illinois, harvesting invasive
plants for use as biofuels may sound like a great idea, but the
reality poses numerous obstacles and is too expensive to consider,
at least with the current ethanol pathways.
"When the topic of potential invasion by nonnative biofuel crops
has been raised at conferences I've attended, the ecologists in
the room have suggested we use biomass from existing invaders
instead," said Lauren Quinn, an invasive plant ecologist in U of
I's Energy Biosciences Institute. "They worry about the
potential deployment of tens of thousands of acres of known
invaders like Arundo donax for ethanol production. They'd say,
‘We have all of these invasive plants. Let's just harvest them
instead of planting new ones!' But when I analyzed the idea from
a broader perspective, it just didn't add up."
the idea of harvesting invasive plants from many angles but said
that the overarching problem is the nonsustainability of the
profit stream. "From a business person's perspective, it just
doesn't function like a typical crop that is harvested and then
replanted or harvested again the following year," she said.
"Here, land managers are trying to get rid of an invasive plant
using an array of methods, including herbicides, so there
wouldn't necessarily be multiple years of harvest."
Other obstacles Quinn examined are the need for specially
designed harvesting equipment, the development of new conversion
technologies for these unique plants, and even the problems
associated with transportation.
"One of the biggest issues is the absence of appropriate
biorefineries in any given area," Quinn said. "If there isn't
one nearby, growers would have to transport the material long
distances, and that's expensive."
Perhaps more important, Quinn discussed the issues with the
high variability of the cell wall composition across different
species. "Most existing or planned biorefineries can process
only a single, or at best, a small handful of conventional
feedstocks, and are not likely to be flexible enough to handle
the variety of material brought in from invasive plant control
projects," Quinn said. "The breakdown and processing of plant
tissues to ethanol requires different temperatures, enzymes and
equipment that are all highly specific. The proportion of
cellulose, lignin and other fractionation products can differ
even within a single genotype if it is grown in multiple
regions, so the variations between completely different plant
types would be an even greater hurdle."
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Quinn isn't discounting the idea of harvesting invasive plants,
however. She encourages control of invasive populations and
subsequent ecological restoration but does not believe that invasive
biomass can replace dedicated energy crops at present.
"One day there might be a pathway toward ethanol conversion of
invasive biomass," Quinn said. "But until we do get to that point,
there may be possibilities to use invasive plants as alternative
sources of energy, like combustion for electricity. Invasive biomass
could drop into the existing supply of biomass being co-fired with
coal in the already huge network of electrical power plants across
the country. That would eliminate the technological barriers that
conversion to ethanol presents.
"I'm not saying that we shouldn't continue to look at ethanol
conversion processes eventually, I'm just saying that right now, it
doesn't seem to make a lot of economic sense."
"Why not harvest existing invaders for bioethanol?" was published
in a recent issue of Biological Invasions. A. Bryan Endres and
Thomas B. Voigt contributed. The research was funded by the Energy
[Text from file received from the
University of Illinois College of Agricultural, Consumer and
The Energy Biosciences Institute, funded
by the energy company BP, is a research collaboration that includes
the University of Illinois, the University of California at Berkeley
and Lawrence Berkeley National Laboratory. It is dedicated to
applying the biological sciences to the challenges of producing
sustainable, renewable energy for the world.