 "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."Quinn explored 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
Biosciences Institute.
[Text from file received from the
University of Illinois College of Agricultural, Consumer and
Environmental Sciences]
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.
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