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National Corn Growers Association (NGCA) Response to
Science Magazine
THE IMPACT OF LAND USE CHANGE ON BIOFUEL LIFECYCLE GHG EMISSIONS
Two articles published by Science Express (the online version of Science magazine) on February 7 discuss the impacts of land use changes caused
by biofuels demand on overall greenhouse gas (GHG) emissions. Both
articles conclude that carbon emissions released from the conversion of
forest and grassland to cropland (in response to increased demand for
grains and oilseeds) would render biofuels far worse than fossil fuels in terms of lifecycle greenhouse gas emissions.
Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through
Emissions from Land Use Change by Searchinger et al. states, "corn-based
ethanol, instead of producing a 20% savings, nearly doubles greenhouse
emissions over 30 years and increases greenhouse gasses for 167 years.
Biofuels from switchgrass, if grown on U.S. corn lands, increase
emissions by 50%. This result raises concerns about large biofuel mandates..."
Land Clearing and the Biofuel Carbon Debt by Fargione et al. concludes, "Converting rainforests, peatlands, savannas, or grasslands to produce
food-based biofuels in Brazil, Southeast Asia, and the United States
creates a 'biofuel carbon debt' by releasing 17 to 420 times more CO2
than the annual greenhouse gas (GHG) reductions these biofuels provide
by displacing fossil fuels."
These articles come on the heels of a January 12 memo to the California
Air Resources Board (CARB) from U.C.-Berkeley professors Alex Farrell
and Michael O'Hare that suggests current lifecycle models do not
properly account for GHG emissions resulting from land use change and
that "...the overall result (is) that land use change will be found to
be a very large contributor to the global warming impact of the
biofuels." To illustrate the current thinking at UC-B, a January 17
presentation by O'Hare suggested that the direct and indirect land use
change of growing corn on previous CRP ground would result in total
ethanol lifecycle emissions of 228 g CO2-eq./MJ, which is nearly 2.5
times worse than gasoline.
The current thought processes demonstrated by the Science articles and
recent communications from UC-B on land use change assumptions and the
associated impact on lifecycle GHG emissions are important because of
their influence on regulatory regimes currently under development. In
January 2007, California Gov. Arnold Schwarzenegger signed an executive
order requiring that by 2010, state GHG emissions must be equivalent to
2000 levels (a ~10% reduction from baseline GHG emissions) and that by
2020 state GHG emissions must achieve a 25% reduction from baseline
levels. Additionally, EPA is mulling how best to implement the
provisions of the 2007 Energy Bill, which will ultimately require a
lifecycle analysis-based mechanism to determine the wheel-to-well GHG
emissions of renewable fuels resulting from various feedstocks.
Talking Points
1. Analyzing the impact of increased biofuels production on
domestic and international land use change is a complex process and a
relatively new area of study for the scientific community.
2. Stakeholders need to demand that the best science is brought to
bear in this debate. The scientific community should be discouraged from "rushing to judgment" on these issues simply to satisfy political
timetables. All serious scientific efforts and approaches must be given
an opportunity to contribute. At present, it is not clear that the
process is fully open to the best science and ideas, and there is a
critical need to open up the process.
3. Land use changes cannot be looked at in the singular context of
increased biofuels production. The impacts and interplay of numerous
global economic, social and political factors on land use also need to
be considered. In particular, it is imperative that the impact of global
energy markets on agricultural markets (and specifically land use) are
understood and properly modeled. Current models do not thoroughly
account for these factors.
4. Using the logic of the Science articles, one could argue that
the "carbon debt" associated with increased cultivation should actually
be charged to the petroleum industry because higher oil prices and
tighter supplies encouraged renewable fuels growth.
5. The effects of population growth on physical land use changes
(such as increased urban and suburban development and the associated
loss of land for other uses) need to be considered in any analysis of
this issue. As an example, according to the University of Nebraska, tens
of millions of acres of arable land in the U.S. have been lost since
1950 to urban and suburban growth.
6. Among the other factors influencing land use that bear scrutiny
are currency valuations and fluctuations; land values; country-specific
conservation and environmental policies; and the effect of economic
growth on diet changes. There are also other physical constraints on the
interchangeability of land use in most countries. It seems much of the
current thinking on land use change assumes land is readily convertible.
7. This debate appears to suffer from a lack of understanding of
current tillage practices and crop yield growth. Further, the value,
carbon intensity, and usage of biofuel coproducts (like distillers
grains) needs more thorough analysis in the context of land use change.
Additionally, continuous corn systems store more carbon than corn/soy
rotation systems, a fact that seems to be lost on many of the academics
considering these issues.
8. Carbon debt in soil is mitigated through better tillage and
nutrient management practices. Carbon debt in soil should be spread
over all the acres attributed to corn, or at least those that produce
grain for ethanol production. It should not be evaluated on a per acre
basis for converted land alone, as is the case in the recent article in
Science.
9. The role of the potential to increase corn yields on existing
farmland, while at the same time increasing the efficiency of fertilizer
and water use and protecting water and soil quality must also be
considered. There is an urgent need for more rigorous scientific
evaluation of the most likely rates of gain in corn yields while
protecting the environment and reducing GHG emissions associated with
corn production using new technologies and approaches. Future growth in
productivity is much more likely to come from higher yield per acre than
through expanded acres.
10. The GHG intensity estimates for ethanol vary widely depending on
what lifecycle model is used. The latest information from UC-Berkeley
shows a value of 88 g CO2-eq./MJ for "Midwest corn ethanol," which is
only slightly better than the 94 g CO2-eq./MJ for gasoline. The GREET
model default is about 76 g CO2-eq./MJ and the University of Nebraska's
BESS model shows a value of 48 g CO2-eq./MJ for typical corn ethanol.
This wide disparity demonstrates the need for more research and data
collection. The GREET model is still using ethanol energy use default
values from a 2001 ethanol plant survey. Most of the plants built since
then are dry mills and require much less energy per unit of production.
11. Many in the scientific community are questioning the
transparency of the model being employed by CARB and UC-B for modeling
of the California LCFS. According to one professor from a Midwestern
land grant university, "...it has not been possible for those outside
the CARB-LCFS process to verify all of the underpinning assumptions and
input parameters that (they) used to obtain their carbon intensity value
(for corn ethanol)."
12. While is should be relatively straightforward to estimate the "carbon debt" from direct effects, such as conversion of CRP land to
corn production as a result of higher corn prices due to expansion of
ethanol production, it will be much more difficult and complex to
estimate the indirect effects, such as clearing of Brazilian rain forest
or Cerrado resulting from corn-ethanol expansion. As an example, from
2000-2004 more than 2 million hectares per year were converted to
soybean production in Brazil, all of it from land that had recently been
in native Cerrado or rainforest. This conversion obviously did not occur
as a result of soybean acres being displaced in the U.S.; in fact
soybean acres during this period averaged 74.3 million acres, well above
the 10-year average (98-99 to 07-08) of 72.8 million acres. This
conversion in Brazil also occurred well before global biodiesel markets
could truly be considered a major driver of oilseed and vegetable oil
demand.
Geoff Cooper
Director, Ethanol & Business Development
National Corn Growers Association
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