West Lafayette, Indiana
October 3, 2008
While cellulosic biofuels derived
from grasses, crop residues and inedible plant parts have real
potential to be more efficient and environmentally friendly than
grain-based biofuels like corn ethanol, more research and
science-based policies are needed to reap these benefits, says
an international group of experts.
In an article published Friday (Oct. 3) in the journal
Science,
Purdue University
agricultural economist Otto Doering and a team of 22 other
scientists write that there is an urgent need for more
comprehensive and collaborative research. This will help
next-generation fuels avoid the pitfalls of grain-based
biofuels, which include increased nutrient runoff and clearing
of new land to recoup lost food production, Doering said.
"It's important that we begin thinking about how to deal with
the unintended consequences of cellulosic biofuels as early as
possible in order to ensure that they can be produced
sustainably," Doering said.
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One-year-old Miscanthus grasses border corn fields near
Purdue's West Lafayette campus. These grasses and other
types of cellulosic energy crops promise to be more
efficient and environmentally friendly than grain-based
biofuels, but more research is needed, said Purdue
agricultural economist Otto Doering. (Purdue University
photo/Alex Turco) |
The Renewable Fuel Standard within
last year's energy bill guarantees cellulosic biofuels a
relatively bright future, mandating that American companies
purchase 21 billion gallons of cellulosic ethanol by 2022. But
many questions remain unanswered, like how to comprehensively
measure the impact of biofuels. To date, measures often reflect
a single dimension rather than considering the system as a
whole.
"There are a broad array of concerns," Doering said. "We need to
consider biofuel's likely impact on water use and availability
along with water quality, especially nutrient runoff. Greenhouse
gas emissions must also be considered, as well as effects on
soils and the landscape."
Rising demand for corn grain ethanol has gone hand-in-hand with
increased water use and, oftentimes, increased nutrient runoff,
Doering said. There also is mixed evidence that corn grain
ethanol reduces greenhouse gas emissions. The intensive corn
cultivation encouraged by high ethanol demand can degrade soil
and water quality, he said.
Doering, recently appointed to the Environmental Protection
Agency's Scientific Advisory Board, said more work is needed to
develop and successfully apply "best management practices" to
minimize nutrient, chemical and water use while limiting
greenhouse gas emissions.
It's important to remember, Doering said, that existing best
management practices can help soften the impact of increased
corn production and intensified agriculture. Such practices
include no-till farming methods, planting of cover crops,
diversity-oriented crop rotation and inclusion of uncultivated
fallow land into the landscape. All these practices help retain
soil nutrients and offer benefits like wildlife habitat and
natural pest suppression.
Cellulose, a complex carbohydrate present in all plant tissues,
is more abundant in plants than starch. Humans also are unable
to digest cellulose. This means cellulosic feedstocks are less
likely to displace acreage devoted to food crops.
"The paper is really a plea to think carefully before jumping
into cellulosics," Doering said. "We want to avoid making
mistakes we're likely to later regret."
Michigan State University researcher G. Philip Robertson was
lead author of the Science article. Authors hail from
universities and institutions from two countries and 16 states.
"Business as usual writ larger is not an environmentally welcome
outcome," the authors conclude.
Writer: Douglas M. Main |
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