© Jupiterimages Corporation.Rising oil prices, combined with an increased awareness
of the effects of greenhouse gas emissions,
have spurred a race to develop alternative sources
of energy. Biofuels—fuels derived from biological
materials—have the potential to decrease America's
dependence on foreign oil, but significant challenges
remain to making biofuels a viable petroleum alternative.
Special attention must be paid to developing
and expanding biofuel production in a socially, environmentally,
and economically sustainable way.
Currently, the main biofuel in the United
States is ethanol derived from corn kernels.
However, the high amount of energy,
water, fertilizer, and pesticides needed to
produce corn makes it an unappealing longterm
biofuel choice. Additionally, corn kernels
are important for food and livestock
feed; therefore, the use of kernels to produce
ethanol has sparked social debates
over "food versus fuel" priorities.
One of the most promising new sources
for biofuel is "cellulosic ethanol," made
from the cellulose in fibrous plant material
such as cornstalks, grasses, and forest
trimmings. Production of cellulosic biofuels
could use plants that require less irrigation,
fertilizer, and pesticides than corn-derived
ethanol per unit of energy gained. However,
the process required to produce cellulosic
ethanol is currently more expensive
than that required for corn kernels.
Large-scale, cost-competitive methods for
producing cellulosic ethanol are a critical
medium-term research goal. For further discussion of corn-derived and cellulosic ethanol, see the National Research Council report
Water Implications of Biofuels Production in the United States.
Genome Research to
Achieve Bioenergy Goals
Image courtesy of the
Genome Management
Information System, Oak Ridge National Laboratory.One reason cellulosic ethanol is harder to
produce than ethanol from corn kernels
is that it requires breaking down relatively
tough cell walls into their component sugars.
This is a necessary step before microorganisms
can ferment the sugars into
ethanol. One way of making this process
easier is to grow plants with weaker cell
walls. Unfortunately, the genes involved in
making and maintaining cell walls are complex
and not yet well understood.
Research on how plant genes control
the composition and structure of their
cell walls could help scientists develop
new energy crops with cell walls that are
easier to deconstruct. In one promising
approach, scientists are engineering corn
to produce the enzymes that break down
cellulose, so that its leaves and stems
would virtually "digest" themselves—but
only after the corn is harvested.
Plant genome sciences could also lead to
other improvements in energy crops, including
maximizing their productivity, increasing
their resistance to pests and drought, and
reducing the need for fertilizers.
This web page is based on the National Academies' educational booklet
New Horizons in Plant Sciences.
