EAST
LANSING, Mich. — Pretreating non-edible biomass – corn
leaves, stalks or switch grass – holds the keys for
unlocking its energy potential and making it
economically viable, according to a team of researchers
led by Michigan State University.
Shishir Chundawat, a postdoctoral researcher, and Bruce
Dale, professor of chemical engineering and materials
science, of MSU led a team of researchers in identifying
a potential pretreatment method that can make plant
cellulose five times more digestible by enzymes that
convert it into ethanol, a useful biofuel. The research
was supported by the Great Lakes Bioenergy Research
Center, a partnership between the University of
Wisconsin and MSU and published in the current issue of
Journal of the American Chemical Society.
Currently, ethanol or other biofuels can only be
produced in usable quantities if the biomass is
pretreated with costly, potentially toxic chemicals in
an energy-intensive process. The new discovery could
change that.
“What we’ve discovered is something like a
cost-effective switch or a lever,” Chundawat said. “By
using an ammonia-based solvent, we were able to pull a
lever and flip the entire cellulose crystal from one
structure to another, one that’s much easier to break
down.”
Biomass is a desirable renewable energy source because
fermentable sugars within the cellulose network of plant
cells can be extracted with enzymes and then converted
into ethanol. Unfortunately, it’s a very complicated
process, and one of the big difficulties in creating
biofuels from plant matter is that cellulose tends to
naturally orient itself into a sheet-like network of
highly ordered, densely packed molecules.
These sheets stack upon themselves and bond together
very tightly due to strong interactions between
molecules – somewhat like sheets of chicken wire stacked
together and secured by loops of bailing wire. This
stacking and bonding arrangement prevents enzymes from
directly attacking most of the individual cellulose
molecules and isolating the sugar chains within them.
During pretreatment, researchers removed water and
increased the ratio of ammonia. The result was seeing
the so-called bailing wire being replaced with loose
thread, which made it vulnerable to conversion into
sugars. The end result is a potentially less costly and
less energy intensive pretreatment regimen that makes
the cellulose five times easier to attack. While
increasing the rate of enzyme success improves biomass
conversion, this research also opens the door for future
improvement of cellulose-degrading enzymes.
Chundawat and Dale worked with researchers from the
GLBRC and the U.S. Department of Energy's Los Alamos
National Laboratory. The GLBRC is one of three
Department of Energy Bioenergy Research Centers funded
to make transformational breakthroughs that will form
the foundation of new cellulosic biofuels technology.
The GLBRC is led by the University of Wisconsin, with
MSU as the major partner. Additional scientific partners
are DOE National Laboratories, other universities and a
biotechnology company.
For
more information, visit
www.glbrc.org.
LANL is a multidisciplinary research institution engaged
in strategic science on behalf of national security. For
more information, visit
www.lanl.gov. |