Lincoln, Nebraska
March 22, 2004
By Vicki Miller
IANR News Service
This story is from the spring/summer issue of Research Nebraska
magazine, which is published twice annually by the
University of Nebraska's
Agricultural Research Division in the Institute of Agriculture
and Natural Resources.
Dan Walters thinks ethanol gets a bad wrap energywise and he's
got numbers to prove it.
Grain-based ethanol is a cleaner-burning, renewable alternative
to fossil fuels. But critics cite studies showing ethanol
production uses more energy than it produces.
"The problem is that's all old data," said Walters, a University
of Nebraska-Lincoln soil scientist. Such studies are based on
figures from the late 1980s and early 1990s, yet much has
changed in agriculture and ethanol production in the past
decade.
"If you're making public policy, we need modern data that
reflects the energy efficiencies of current or future farming
and ethanol processing," he said. To calculate a modern energy
balance for ethanol, Walters gathered and assessed current
information on all the fossil fuel needed to grow and transport
corn and to convert it to ethanol, blend it with gasoline and
get it to the pump.
Today's ethanol has a positive energy balance, he found. It
provides more energy than is used to produce it. Walters
calculated the energy output to energy input ratio for
converting irrigated corn to ethanol is 1.3-to-1 and 1.4-to-1
for dryland corn.
"We're about 30 percent ahead" energywise, the Institute of
Agriculture and Natural Resources scientist said.
Advances in ethanol conversion and plant efficiency are part of
the equation, he said. In 2002, a bushel of corn produced 2.7
gallons of ethanol, up from 2.5 gallons in 1990. Ethanol
byproducts such as livestock feeds enhance efficiency because
energy would be needed to produce these products if they weren't
made during ethanol conversion.
On the crop production side, nitrogen is the largest energy
factor, accounting for 30 percent to 50 percent of all energy
needed to raise corn, Walters said. Nitrogen efficiency has
improved immensely over the past 20 years, and continues
improving by an average .013 bushels of grain per pound of
nitrogen annually.
Improvements in seed genetics, water use, crop management and
production equipment also help boost efficiency.
"These efficiencies rely on normal best management practices and
judicious nitrogen use to optimize, not maximize, productivity,"
he said. Much of Walters' production data comes from 160-acre
fields in the university's ongoing carbon sequestration
research, but he said national averages are similar.
"I'm confident we're still in positive energy balance," he said.
Irrigation requires extra energy but compensates by boosting
yields and nitrogen efficiency, Walters said.
"That bodes very well for Nebraska," he said, where irrigation
is widely used and 23 percent of the corn crop is sold for
ethanol. "We can compete with rainfed corn growing states for
ethanol production."
Walters calculated the ethanol energy balance while working on
broader energy use and carbon assessments for the carbon
sequestration project. More than half of corn's carbon is in
grain, but scientists don't factor it in long-term carbon
storage because grain's carbon recycles back to the atmosphere
as feed or food in a year or so.
But converting grain to ethanol helps offset carbon emissions
from fossil fuels, Walters said.
Typically, 10 percent ethanol is blended with conventional
unleaded gasoline to produce E-10 Unleaded.
"When we put gasoline in our car, we're using carbon that has
been stored for millions of years," Walters explained. "When we
put E-10 in the tank, carbon dioxide emissions are 10 percent
less than someone who burns straight fossil fuel because ethanol
is a biofuel. It's made with carbon from the atmosphere that's
recycled through the corn plant."
He predicts ethanol's energy equation will continue improving
along with farming and processing efficiencies.
"That picture gets better and better."
A U.S. Department of Energy grant helps fund NU's carbon
sequestration research. |
